JP7497949B2 - Foam booster, premix solution containing same, polyurethane foam-forming composition containing same, and polyurethane foam with improved hydrophobicity - Google Patents

Description

The present invention relates to a foam enhancer containing a silicone polyether copolymer having a specific structure for a water-blown polyurethane spray foam system containing a) a specific polyether polyol, b) a polyisocyanate, c) a curing catalyst, and d) water as a main blowing agent, and the foam enhancer has an excellent hydrophobicity improving effect on polyurethane foams obtained by the system, particularly soft polyurethane foams. The present invention also relates to a premix solution containing the components a) to d) and the foam enhancer containing the silicone polyether copolymer, and to a polyurethane foam forming composition that may contain these components and optionally other additives. The present invention also relates to a polyurethane foam and a method for improving the hydrophobicity thereof using the foam enhancer containing the silicone polyether copolymer. In the following description, "foam" means polyurethane foam unless otherwise specified.

A method of applying an insulating layer by on-site foaming has been used for the insulating construction of various buildings such as houses, refrigerated warehouses, and tank facilities. The material of the insulating foam layer is often foamed polyurethane formed by reacting polyisocyanate and polyol in the presence of a foaming agent. In general, a raw material mixture containing a foaming agent is injected or sprayed into the gaps of the construction area, where it is reacted and hardened to form an insulating layer of foamed polyurethane. The types of foamed polyurethane used here are roughly divided into two types. One is a rigid foam structure called "rigid polyurethane foam" that has a closed cell structure and contains a foaming agent gas with low thermal conductivity inside. The other is "soft polyurethane foam" that has a structure with small holes in the walls between adjacent cells, which gives the foam breathability and is characterized by a flexible foam structure. The former has excellent insulating properties but generally lacks compliance when a load is applied, and is more expensive than the latter. On the other hand, the latter has inferior insulating properties to the former but has compliance to load, and is therefore expected to have excellent durability when the building is shaken: the resistance to breakage of the substrate-polyurethane adhesive surface is excellent. Therefore, the former is suitable for use in strong concrete structures such as buildings and blocks, while the latter is more logical for use in, for example, individual wooden houses, where low cost is important. For the latter, water is preferably used as the blowing agent from the viewpoints of environmental consideration and cost. In this case, water reacts with isocyanate to generate carbon dioxide, so carbon dioxide acts as the true blowing agent. In recent years, the need for further cost reduction has intensified, and low-density foam formulations with high expansion ratios (i.e., high water usage) have become widespread. From a cost-in-use perspective, sellers of such foaming polyurethane systems tend to seek foam stabilizers that can form a larger volume of foam with the same amount used, and currently, commercially available foam stabilizers for general-purpose soft slab foams are used as they are also suitable for residential insulation spray foam systems.

Such a foamed polyurethane insulation layer is usually located between the exterior wall of a house and the interior wall on the indoor side. Therefore, in cold seasons such as winter, when the warm, humid air from the indoor side moves into the interior of the insulation layer, it may be cooled from the exterior wall side and cause condensation. Condensation is a cause of concern that it may cause mold to grow, and it may also lead to deterioration of the polyurethane, so there has been a demand for the development of a foamed polyurethane system with lower moisture permeability or water absorption. In addition, such a foamed polyurethane insulation layer can also be used as a sound absorbing layer that effectively absorbs impact noise on the upper floor by being located between the upper floor and the lower ceiling of a house. This is because the foamed polyurethane is not a closed-cell type but a connected type based on an open cell structure, so sound can easily enter the cells and is efficiently attenuated within the cells, resulting in high sound insulation.

On the other hand, polyether-modified silicones can be designed with various structures and average molecular weights, and the surfactant properties, compatibility with blowing agents, and affinity with polyurethane foam systems can be controlled by the EO wt. % and size of the polyether part, introduction of lipophilic groups into the silicone main chain, variation of the silicone main chain structure, introduction site of the modified group, modification with two or more different polyether groups, etc. Therefore, polyether-modified silicones have long been known to be useful as surfactants (foam stabilizers) for bubble control or bubble stabilization in all polyurethane foam formulations, such as rigid foams, semi-rigid foams, HR (high elasticity) foams (hereinafter sometimes simply referred to as "HR foams"), soft foams, and microcellular foams, and many varieties have been commercially manufactured and sold to date, making a significant contribution to the development of the polyurethane foam industry.

However, in-situ foaming spray foam for building insulation, which requires the addition of a large amount of water, is considered to be a relatively new technology field in the long history of the polyurethane foam industry. In other words, within the scope of the inventors' investigations, no detailed reports have been made so far on the chemical structure of polyether-modified silicone foam stabilizers, the performance of the foam stabilizers in the spray foam formulation, or the correlation with the resulting foam properties. This is thought to be because existing foam stabilizers for soft slab foams could be repurposed for this foam system, so there was little need for polyether-modified silicone manufacturers to develop new foam stabilizers.

Generally, soft polyurethane foams, such as soft slab foams, are the oldest of all polyurethane foams. The first soft polyurethane foams in the 1950s were produced using a two-step reaction method called the prepolymer method, using polyester polyol as a raw material. In 1956, the discovery of an organotin catalyst, a silicone foam stabilizer, and a combination of an amine catalyst and a tin catalyst led to the commercial production of one-shot soft polyurethane foams using polyester polyol and TDI (tolylene diisocyanate) as the main raw materials. In 1957, Union Carbide began commercial production of polyether polyols as a cheaper raw material, and the following year, in 1958, the company discovered a catalyst suitable for the new polyol, a polyether-modified silicone foam stabilizer, and a manufacturing process for one-shot soft polyether urethane foams using these (Patent Document 1). This marked the beginning of the global growth of the polyurethane foam industry. This first polyether-modified silicone foam stabilizer had a structure in which polyether groups and polysiloxane groups were linked by Si-O-C bonds and was susceptible to hydrolysis, so Dow Corning developed a new non-hydrolyzable polyether-modified silicone foam stabilizer in which polyether groups and polysiloxane groups are linked by Si-C bonds (Patent Document 2).

Since then, many foam stabilizers for flexible foams have been developed. The motivation for the need for new foam stabilizer technology is often due to legal regulations and requirements such as chemical substance management, reduction in foam manufacturing costs, as well as changes and improvements to foam formulations to meet the subdivided uses of flexible polyurethane foams and the required foam properties. For example, the following cases can be mentioned. I) When a certain flame retardant or flame retardant component was newly formulated into a polyurethane system based on a flame retardant, the foam stabilizer used in the original formulation was insufficient in compatibility with the system and in the foam characteristics obtained, so a new foam stabilizer was needed for the improved formulation. II) In old formulations, fluorocarbon gas was used as a blowing agent, but since it was revealed that it is a substance that causes ozone layer destruction and a greenhouse gas, various international agreements and laws imposed significant restrictions on its use, mainly in developed countries. Prior to that, when updating to a new formulation using alternative fluorocarbons or a different substance as a blowing agent, a new foam stabilizer was needed because the foam stabilizer used in the original formulation was insufficient in compatibility with the system (or new blowing agent) and in the foam characteristics obtained. III) In order to commercialize a flexible polyurethane foam with certain physical characteristics, a new polyurethane foam system was developed using a polyol with a new structure (or a specific combination of polyols), and since there were no existing foam stabilizers that were compatible, a new foam stabilizer was needed. IV) Examples related to reducing foam production costs include IV-1) a foam stabilizer with a wider processing latitude: that is, a foam stabilizer that has less impact on foam properties due to fluctuations in the amount used (for the purpose of improving the yield of foam products), IV-2) a foam stabilizer that can form normal foam with a smaller amount used, IV-3) a foam stabilizer that can further stabilize or improve the foam stability that affects foam properties, and IV-4) a foam stabilizer that can improve the chemical/physical or performance stability of the premix liquid. For each of these various flexible polyurethane foam formulations, polyether-modified silicone foam stabilizers with optimized structures and compositions are usually developed and used.

However, based on the many years of research and experience of both silicone foam stabilizer manufacturers and polyurethane foam manufacturers, there is one requirement that is clearly understood about the structural elements of polyether-modified silicones required for flexible polyurethane foams. That is, the silicone must be modified with a polyether group in which the hydroxyl group at the end of the polyether chain is blocked by alkoxylation or acetoxylation. Commercially available foam stabilizers for flexible slab foams generally meet this requirement. Otherwise, excessive stabilization of the bubbles will occur during the urethane reaction and foaming process, and holes will not open in the walls of adjacent cells, resulting in a closed-cell foam structure. Since the resin skeleton of flexible polyurethane foam is flexible, when a closed-cell structure is formed, the entire foam will shrink as the gas volume trapped inside the cells shrinks when the reaction heat subsides and the temperature returns to room temperature, making it unusable. Therefore, it is common technical knowledge in the industry that polyether-modified silicones in which the polyether chains with hydroxyl groups at the end form the main part of the polyether group are worthless for flexible polyurethane foams. Conversely, EO wt. Silicones modified with polyether chains having a high PO wt. % and hydroxyl groups at the end are often used in general rigid polyurethane foams (including PIR: polyisocyanurate foams) that require a closed-cell type microcellular structure. In other words, silicones modified with polyether chains having a high PO wt. % and hydroxyl groups at the end are recognized as unnecessary from a commercial practical standpoint in the polyurethane foam stabilizer field.

Patent Document 3 disclosed i) a solution composition for producing polyurethane foam, which contains water, a polyether-modified silicone having a specific structure, an amine catalyst, and a silicon-free organic surfactant that is water-soluble and can improve the cloud point, in a specific ratio, and ii) a process for producing flexible polyurethane foam using the solution composition. In the patent document 3, a PDMS (polydimethylsiloxane) side-chain-modified with a polyether chain having a hydroxyl group at the end was used as "Comparative Copolymer I", and a solution composition containing the same was used as "Comparative Premix Liquid K-2". As a result of testing the resulting soft molded foam in a soft molded foam formulation, it was reported that a foam that was too dense and had poor breathability was obtained. In this foam formulation, fluorocarbon gas was the main blowing agent, and the number of parts of water added per 100 parts of polyol was 5.5 parts.

Patent Document 4 disclosed i) an improvement to the cold cure, high resilience (HR) polyurethane foam manufacturing process, in which a polyether-modified silicone of a specific structure in which two types of polyether chains with different EO wt. % are grafted to a short polysiloxane backbone is used as a foam stabilizer, and ii) the foam obtained thereby. In this, PDMS side-chain-modified with two different types of polyether chains terminated with hydroxyl groups was prepared in "Example 5" and tested in four types of HR molded foam formulations. In these foam formulations, water was the main blowing agent, and the amount of water added per 100 parts of polyol was as small as 2.0 to 3.7 parts.

Patent Document 5 discloses i) a process for producing rigid polyurethane foam using a polyether-modified silicone foam stabilizer of a specific structure having two types of polyether chains with different EO wt. %, ii) the polyether-modified silicone foam stabilizer, and iii) an article filled with foam obtained by the process. In the document, it was reported that PDMS side-chain-modified with a polyether chain terminated in a hydroxyl group was tested as "Comparative Foam Stabilizer VI" in two types of rigid molded foam formulations, and that foams with a large density gradient in which the edge zone near the mold was compressed were obtained. In these foam formulations, fluorocarbon gas was the main blowing agent, and the amount of water added to 100 parts of polyol was as small as 1.0 to 2.0 parts.

Patent Document 6 disclosed a method for producing polyurethane foam using a foam stabilizer made of organopolysiloxane of a specific structure having a polyether chain derived from a polyether compound obtained by ring-opening polymerization of alkylene oxide with a composite metal cyanide complex catalyst. In this method, two types of PDMS modified at the side chain with a polyether chain having a hydroxyl group at the end were prepared as "Foam stabilizer A (Production method 1: for Example 1) and Foam stabilizer E (Production method 5: for Comparative example 4)" and tested in a hot cure mold flexible foam formulation. In this document, this foam formulation is also simply referred to as flexible polyurethane foam, but since the formulation contained a polymer polyol, it is clear that it was a HR foam formulation rather than a general flexible foam. In this foam formulation, water was the main blowing agent, and the amount of water added per 100 parts of polyol was 5.5 parts.

Patent Document 7 disclosed a method for producing polyurethane foam using a mixture of PDMS with a relatively high degree of polymerization, modified with two types of polyether chains with different EO wt. % and average molecular weights, and a diluent (where the viscosity of the mixture is less than 3000 cP), and water as a blowing agent. The foam type that this technology mainly targets is considered to be general soft foam, and most of the polyether-modified silicones given as examples were "silicones modified with polyether groups in which the hydroxyl groups at the ends of the polyether chains are blocked by alkoxylation or acetoxylation." The only one, "No. 68," was a PDMS modified with three types of polyether chains with hydroxyl groups at the ends, which was prepared and diluted and then tested in a high-water content soft polyurethane foam formulation, but it was noted that a foam with extremely low air permeability was obtained despite the coarse cell size and splits. Although this water-blown soft foam formulation was described as a "high water content test," the amount of water added was only 6.5 parts per 100 parts of polyol.

Patent Document 8 disclosed i) an HR polyurethane foam composition which is a reaction product of a polyisocyanate and a polyol in the presence of a dry or semi-dry liquid vegetable oil (or its derivative) having a boiling point of 175°C or higher and an organosiloxane copolymer surfactant, and ii) a process for producing the foam. In this document, several examples of preparation of mixtures of PDMS modified with a polyether chain having a hydroxyl group at the end and various solvents were reported, but the copolymer solutions tested in the actual HR molded foam formulations (four types) were limited to mixtures of the vegetable oil and a structure in which a short-chain polyether was grafted to a PDMS main chain having a low degree of polymerization. In these foam formulations, water was the main blowing agent, and the amount of water added per 100 parts of polyol was as small as 3.8 to 4.2 parts.

Patent Document 9 disclosed i) a rigid and stable open-cell polyurethane foam obtained by using an ABA' type linear polyether-polysiloxane copolymer having hydroxyl-terminated polyethers at both ends, and ii) a manufacturing process thereof. In this document, PDMS side-chain-modified with hydroxyl-terminated polyether chains was tested in two types of high-density soft microcellular foam formulations in "Comparative Example 34, Comparative Example 38, and Comparative Example 41," and the results reported showed that one of the formulations caused severe foam shrinkage. Water was thought to be the main blowing agent under the test conditions, but the amount of water added was very small, at 1 part per 100 parts of polyol.

Patent Document 10 disclosed i) a composition consisting of a polyether-modified silicone and a specific monoalkyl glycol ether diluent having one secondary hydroxyl group in the molecule and an oxyalkylene repeat number of 2 to 3, ii) a surfactant, foam stabilizer, polyurethane foam-forming composition, and polyurethane foam containing the same, and iii) a method for producing a composition consisting of the polyether-modified silicone and a diluent. Among them, a composition containing a PDMS side-chain-modified with a polyether chain having a hydroxyl group at the end and a diluent was prepared as "Example 2-1". In addition, two examples of flexible polyurethane foam formulations (not implemented) in which some of the example compositions can be used as foam stabilizers are shown. In these foam formulations, methylene chloride is the main blowing agent, and the amount of water added per 100 parts of polyol is 5.5 parts or 3.3 parts.

To summarize the above, Patent Documents 1 and 2 do not disclose silicone foam stabilizers modified with polyether chains whose terminals are hydroxyl groups. Patent Documents 3 to 10 disclose several examples of silicones whose PO wt. % is high and whose terminals are hydroxyl groups, and their application to various foam formulations has been attempted, but in many cases, they were treated as comparative examples and poor performance was reported. Alternatively, there were cases in which compositions containing the silicone were prepared, but performance confirmation by actual foaming evaluation was not performed. In addition, there was no mention of spray foam in any of the prior documents, and the foam formulations implemented and the foams obtained were completely different from spray formulations and foams obtained thereby. For example, in a 100-fold expanding spray foam formulation in which water is the main blowing agent, the amount of water used is extremely high, usually 10 to 40 parts per 100 parts of polyol, and is characterized by the fact that a low-density foam is obtained, but the range of the amount of water added used in the formulations of various foam types in the prior documents is only 1.0 to 6.5 parts, which is significantly different from the content of the present invention. In addition, general-purpose foam stabilizers for flexible slab foams currently being used in residential insulation spray foam systems are suitable for increasing foam volume, but are unable to meet the need to reduce the moisture permeability or water absorption of the foam. Furthermore, these prior art documents make no mention, test or confirmation of the knowledge of the present invention that the hydrophobicity of the urethane foam itself can be improved by selecting a specific chemical structure for the polyether-modified silicone used as a foam stabilizer for urethane foam.

As described above, Patent Documents 1 to 10 do not provide any explanation of spray foam formulations, and therefore no study was conducted on on-site foaming spray foam formulations for building insulation, which are characterized by the use of a large amount of water and a polyol for flexible polyurethane foam. Therefore, there was no description or suggestion of the chemical structure of the polyether-modified silicone foam stabilizer, the performance of the foam stabilizer in the spray foam formulation, or the correlation with the obtained foam properties. Furthermore, for this application, 1) compatibility with premix systems, 2) imparting a larger foam volume, and 3) imparting a finer open cell structure are generally expected performances of a foam stabilizer, but there is no description or suggestion of the currently required 4) method of lowering the moisture permeability or water absorption of the foam itself (or improving the hydrophobicity of the foam). For this reason, there is no effective approach in existing technology for a person skilled in the art to improve the hydrophobicity of polyurethane foam by selecting the chemical structure of the foam stabilizer, and it was difficult to predict the technical effects.

Against this background technology, there is a need for a technology that solves the above technical problems and further uses a specific raw material/foaming/curing system, and in which the resulting polyurethane foam satisfies the above requirements. There is also a need for a technology that effectively improves the hydrophobicity of polyurethane foam.

U.S. Pat. No. 3,817,822 U.S. Pat. No. 3,398,104 U.S. Pat. No. 3,669,913 U.S. Pat. No. 4,478,957 U.S. Pat. No. 4,529,743 Patent No. 3135318 (JP Patent Publication No. 5-117352) U.S. Pat. No. 5,489,617 U.S. Patent No. 6,071,977 (Patent No. 4,366,470) U.S. Patent No. 8,436,064 (Patent No. 5,743,544) European Patent Application Publication No. 3530703 (International Publication No. 2018-074257)

The present invention has been made to solve the above problems, and aims to provide a foam enhancer that is particularly suited to water-blown polyurethane spray foam systems that can form large volumes of foam at construction sites and the like by adding a large amount of water and using a small amount of foam stabilizer (foam enhancer), has excellent compatibility with premix systems, can form large volumes of foam suitable for building insulation applications with a small amount of use, and can produce foam with a fine cell structure and significantly improve the hydrophobicity of the foam obtained. In this problem, it is particularly preferable that the foam is a soft urethane foam.

Furthermore, the present invention aims to provide a premix solution containing the foam enhancer and suitable for a water-blown polyurethane spray foam system, a polyurethane foam forming composition containing the foam enhancer, and a polyurethane foam (particularly a flexible polyurethane foam) obtained by using the foam enhancer and having significantly improved hydrophobicity, and uses thereof (thermal insulation material/sound absorbing material, etc.).

Furthermore, based on the unexpected discovery that the hydrophobicity of polyurethane foam can be significantly improved by selecting the chemical structure of the silicone polyether copolymer, the present invention aims to provide a method for improving the hydrophobicity of polyurethane foam, which is not limited to a specific spray foam system, by using a foam enhancer containing the silicone polyether copolymer.

The present invention solves the above problems, but the inventors have also discovered a new problem with polyurethane foam-forming compositions and polyurethane foams prepared therefrom. That is, in recent years, there has been an increasing demand in the market for polyurethane foam (hereinafter sometimes abbreviated as "urethane foam" or "foam") materials for low emissions, i.e., "low emission properties." This is a required characteristic that is characterized by a small amount of chemical components that are generated or volatilized from polyurethane foam. Specifically, it is sometimes expressed as a requirement that the amount of volatile components generated from the foam is low (=Low VOC (Volatile Organic Compound)), that the amount of chemicals released from the foam to the outside over time is low to prevent sick house syndrome and allergies (=Low Emission of Chemical Compound), and that the phenomenon in which components that volatilize from foam used inside a car adhere to windows and cause fogging (=Low Fogging), but apart from differences in the types and properties of chemical substances, the actual meaning is essentially the same in that there are few emissions derived from the foam.

A further object of the present invention is to provide a flexible polyurethane foam that satisfies the requirements for low emission/low VOC and is obtained from the polyurethane spray foam forming composition.

｛式中、Ｒは各々独立にアルキル、アリール、アラルキル基から選択される炭素原子数１～１６の１価の炭化水素基を表し、
Ｘは、各々独立に式：－Ｃ_ｋＨ_２ｋＯ－（Ｃ_２Ｈ_４Ｏ）_p（Ｃ_３Ｈ_６Ｏ）_q（Ｃ_４Ｈ_８Ｏ）_r－Ｙで示される１種類または２種類以上のポリエーテル基を表し、
Ｙは、１００モル％がＨ基であるか、７５モル％以上のＨ基と２５モル％以下のＣ１～Ｃ４アルキル又はアセチル基から選ばれるその他の基からなり、
ｍ、ｎ、k、p、q 、r は以下の条件を満たす数である。
１２≦（ｍ＋ｎ）≦２３０、
１０≦ｍ、
２≦ｎ、
ｎ≦ｍ、
3≦ｋ≦4、
ｐ、ｑ、ｒは、Ｘで表されるポリエーテル基部分の式量が１４００～４０００の範囲内にあり、
｛（Ｃ_３Ｈ_６Ｏ）ｑで表されるオキシプロピレン基部分および（Ｃ_４Ｈ_８Ｏ）ｒで表されるオキシブチレン基部分の式量の和｝／｛（Ｃ_２Ｈ_４Ｏ）ｐで表されるオキシエチレン基部分の式量の和）｝である比の値Ｚが、
（５１／４９）≦Ｚ≦（９５／５）の条件を満たす数である。
ただし、式中のXにおいて、１≦ｐかつｑ＝ｒ＝０である構造を有するポリエーテル基は除く。｝
で表されるシリコーンポリエーテル共重合体を含有する泡増強剤により、上記課題を解決できる事を見出し、本発明に到達した。当該泡増強剤は、特定の構成を有する水発泡型ポリウレタンスプレーフォームシステムにおける使用に、特に適しており、かつ、特定のスプレーフォームシステムに限定されない、ポリウレタン発泡体の疎水性を顕著に改善することができる。 As a result of extensive investigation, the present inventors have discovered that a compound represented by the general formula (1):

In the formula, each R independently represents a monovalent hydrocarbon group having 1 to 16 carbon atoms selected from an alkyl, aryl, or aralkyl group;
X's each independently represent one or more polyether groups represented _{by the formula: -CkH2kO-(C2H4O ) p ( C3H6O ) q ( C4H8O ) r} -Y;
Y is 100 mol % H group or is composed of 75 mol % or more H group and 25 mol % or less other group selected from C1-C4 alkyl or acetyl group;
m, n, k, p, q, and r are numbers that satisfy the following conditions:
12≦(m+n)≦230,
10≦m,
2≦n,
n≦m,
3≦k≦4,
p, q, and r each represent a formula weight of the polyether group portion represented by X in the range of 1,400 to 4,000;
The ratio Z, which is {the sum of the formula weights of the oxypropylene group portion represented by (C ₃ H ₆ O)q and the oxybutylene group portion represented by (C ₄ H ₈ O)r}/{the sum of the formula weights of the oxyethylene group portion represented by (C ₂ H ₄ O)p)}, is
This is a number that satisfies the condition (51/49)≦Z≦(95/5).
However, in the formula, a polyether group having a structure where p is 1 or less and q=r=0 is excluded.
The present inventors have discovered that the above problems can be solved by a foam booster containing a silicone polyether copolymer represented by the formula: The foam booster is particularly suitable for use in water-blown polyurethane spray foam systems having a specific configuration, and is capable of significantly improving the hydrophobicity of polyurethane foams, regardless of the specific spray foam system.

Furthermore, the inventors have discovered that the above problems can be suitably solved by a premix liquid for a water-blown polyurethane spray foam system containing the above-mentioned foam enhancer, a polyurethane foam forming composition containing the same, and a flexible polyurethane foam with improved hydrophobicity, a flexible polyurethane foam with low emission/low VOC properties, or a heat insulating material/sound absorbing material prepared therefrom, and have arrived at the present invention.

｛式中、Ｒは各々独立にアルキル、アリール、アラルキル基から選択される炭素原子数１～１６の１価の炭化水素基を表し、
Ｘは、各々独立に式：－Ｃ_ｋＨ_２ｋＯ－（Ｃ_２Ｈ_４Ｏ）_p（Ｃ_３Ｈ_６Ｏ）_q（Ｃ_４Ｈ_８Ｏ）_r－Ｙで示される１種類または２種類以上のポリエーテル基を表し、
Ｙは、１００モル％がＨ基であるか、７５モル％以上のＨ基と２５モル％以下のＣ１～Ｃ４アルキル又はアセチル基から選ばれるその他の基からなり、
ｍ、ｎ、k、p、q 、r は以下の条件を満たす数である。
１２≦（ｍ＋ｎ）≦２３０、
１０≦ｍ、
２≦ｎ、
ｎ≦ｍ、
3≦ｋ≦4、
ｐ、ｑ、ｒは、Ｘで表されるポリエーテル基部分の式量が１４００～４０００の範囲内にあり、
｛（Ｃ_３Ｈ_６Ｏ）ｑで表されるオキシプロピレン基部分および（Ｃ_４Ｈ_８Ｏ）ｒで表されるオキシブチレン基部分の式量の和｝／｛（Ｃ_２Ｈ_４Ｏ）ｐで表されるオキシエチレン基部分の式量の和）｝である比の値Ｚが、
（５１／４９）≦Ｚ≦（９５／５）の条件を満たす数である。
ただし、式中のXにおいて、１≦ｐかつｑ＝ｒ＝０である構造を有するポリエーテル基は除く。｝
で表されるシリコーンポリエーテル共重合体を含有する泡増強剤であって、以下のa)～d)を含む水発泡型ポリウレタンスプレーフォームシステムに適用されるもの：
ａ）分子内の平均水酸基数が２～４であり、オキシプロピレン基からなる繰り返し単位を有し、数平均分子量が１０００～６０００の範囲内にある、１種類以上のポリエーテルポリオール、
ｂ）ポリイソシアネート、
ｃ）硬化触媒、
ｄ）水である発泡剤 同システム中の成分ａ）であるポリエーテルポリオールおよびその他のポリオール成分の和 １００質量部に対して１０～４０質量部の範囲。
［２］前記一般式（１）において、
Ｘが、各々独立に式：－Ｃ_３Ｈ_６Ｏ（Ｃ_２Ｈ_４Ｏ）_p（Ｃ_３Ｈ_６Ｏ）_q－Ｈ
で示される１種類または２種類以上のポリエーテル基であり、
Ｘで表されるポリエーテル基部分の式量が１５００～２５００の範囲内にあり、かつ、
前記の比Ｚが（５４／４６）≦Ｚ≦（８０／２０）の条件を満たす、
［１］に記載の泡増強剤。
［３］前記一般式（１）において、Ｒがメチル基であり、ｍ、ｎが、４０≦ｍ≦９０、かつ、２≦ｎ≦８の条件を満たす、
［１］または［２］に記載の泡増強剤。
［４］前記の水発泡型ポリウレタンスプレーフォームシステムにおいて、
ｂ）ポリイソシアネートが、ＭＤＩ（ジフェニルメタンジイソシアネート）、ポリメリックＭＤＩ（ポリメチレンポリフェニルポリイソシアネート），クルードＭＤＩ，イソシアナート基含有プレポリマー、およびこれらの誘導体から選ばれる成分であり、かつ、
同システムの発泡剤がｄ）水のみであることを特徴とする、
［１］～［３］のいずれか１項に記載の泡増強剤。 That is, the present invention relates to the following foam enhancing agents [1] to [5].
[1]
General formula (1):

In the formula, each R independently represents a monovalent hydrocarbon group having 1 to 16 carbon atoms selected from an alkyl, aryl, or aralkyl group;
X's each independently represent one or more polyether groups represented _{by the formula: -CkH2kO-(C2H4O ) p ( C3H6O ) q ( C4H8O ) r} -Y;
Y is 100 mol % H group or is composed of 75 mol % or more H group and 25 mol % or less other group selected from C1-C4 alkyl or acetyl group;
m, n, k, p, q, and r are numbers that satisfy the following conditions:
12≦(m+n)≦230,
10≦m,
2≦n,
n≦m,
3≦k≦4,
p, q, and r each represent a formula weight of the polyether group portion represented by X in the range of 1,400 to 4,000;
The ratio Z, which is {the sum of the formula weights of the oxypropylene group portion represented by (C ₃ H ₆ O)q and the oxybutylene group portion represented by (C ₄ H ₈ O)r}/{the sum of the formula weights of the oxyethylene group portion represented by (C ₂ H ₄ O)p)}, is
This is a number that satisfies the condition (51/49)≦Z≦(95/5).
However, in the formula, a polyether group having a structure where p is 1 or less and q=r=0 is excluded.
A foam booster containing a silicone polyether copolymer represented by the formula:
a) one or more polyether polyols having an average number of hydroxyl groups in the molecule of 2 to 4, having repeating units composed of oxypropylene groups, and having a number average molecular weight in the range of 1,000 to 6,000;
b) polyisocyanates,
c) a curing catalyst;
d) Water as a blowing agent: in the range of 10 to 40 parts by mass per 100 parts by mass of the sum of the polyether polyol (component a) and other polyol components in the system.
[2] In the general formula (1),
X's each independently represent the formula: -C ₃ H ₆ O(C ₂ H ₄ O) _p (C ₃ H ₆ O) _q -H
is one or more kinds of polyether groups represented by
The formula weight of the polyether group portion represented by X is in the range of 1500 to 2500, and
The ratio Z satisfies the condition (54/46)≦Z≦(80/20).
The foam enhancer according to [1].
[3] In the general formula (1), R is a methyl group, and m and n satisfy the conditions of 40≦m≦90 and 2≦n≦8.
The foam enhancer according to [1] or [2].
[4] In the water-blown polyurethane spray foam system,
b) the polyisocyanate is a component selected from MDI (diphenylmethane diisocyanate), polymeric MDI (polymethylene polyphenyl polyisocyanate), crude MDI, an isocyanate group-containing prepolymer, and a derivative thereof; and
The blowing agent of the system is d) water alone.
The foam enhancer according to any one of [1] to [3].

Furthermore, the present invention relates to the following premix liquid:
[5] A premix liquid for a polyurethane spray foam system comprising the components a) to d) and e) the foam enhancer according to any one of [1] to [4].
[6] The premix liquid for a polyurethane spray foam system according to [5], further comprising: a') at least one polyol component other than the polyether polyol component a).
[7] f) The premix liquid for a polyurethane spray foam system according to [6], further comprising a nonionic surfactant.

Similarly, the present invention relates to the following polyurethane foam-forming composition, flexible polyurethane foam, and uses thereof.
[8] A polyurethane foam-forming composition comprising the foam booster described in any one of items a) to d) and e) [1] to [4] above, and optionally further comprising one or more components selected from the group consisting of component a') and component f).
[9] The polyurethane foam-forming composition according to [8], further comprising g) a flame retardant, and optionally h) other additives.
[10] A flexible polyurethane foam obtained by curing the polyurethane foam-forming composition according to [8] or [9].
[11] The flexible polyurethane foam according to [10], which has low emission/low VOC properties.
[12] A heat insulating material or sound absorbing material comprising the flexible polyurethane foam according to [10] or [11].

｛式中、Ｒは各々独立にアルキル、アリール、アラルキル基から選択される炭素原子数１～１６の１価の炭化水素基を表し、
Ｘは、各々独立に式：－Ｃ_ｋＨ_２ｋＯ－（Ｃ_２Ｈ_４Ｏ）_p（Ｃ_３Ｈ_６Ｏ）_q（Ｃ_４Ｈ_８Ｏ）_r－Ｙで示される１種類または２種類以上のポリエーテル基を表し、
Ｙは、１００モル％がＨ基であるか、７５モル％以上のＨ基と２５モル％以下のＣ１～Ｃ４アルキル又はアセチル基から選ばれるその他の基からなり、
ｍ、ｎ、k、p、q 、r は以下の条件を満たす数である。
１２≦（ｍ＋ｎ）≦２３０、
１０≦ｍ、
２≦ｎ、
ｎ≦ｍ、
3≦ｋ≦4、
ｐ、ｑ、ｒは、Ｘで表されるポリエーテル基部分の式量が１４００～４０００の範囲内にあり、
｛（Ｃ_３Ｈ_６Ｏ）ｑで表されるオキシプロピレン基部分および（Ｃ_４Ｈ_８Ｏ）ｒで表されるオキシブチレン基部分の式量の和｝／｛（Ｃ_２Ｈ_４Ｏ）ｐで表されるオキシエチレン基部分の式量の和）｝である比の値Ｚが、
（５１／４９）≦Ｚ≦（９５／５）の条件を満たす数である。
ただし、式中のXにおいて、１≦ｐかつｑ＝ｒ＝０である構造を有するポリエーテル基は除く。｝
で表されるシリコーンポリエーテル共重合体を含有する泡増強剤を使用することを特徴とする、ポリウレタン発泡体の疎水性の改善方法
に関する。 Furthermore, the present invention is based on the unexpected discovery that the hydrophobicity of a polyurethane foam can be significantly improved by selecting the chemical structure of the silicone polyether copolymer, and provides a method for significantly improving the hydrophobicity of a polyurethane foam, which is not limited to a specific spray foam system.
[13] General formula (1):

In the formula, each R independently represents a monovalent hydrocarbon group having 1 to 16 carbon atoms selected from an alkyl, aryl, or aralkyl group;
X's each independently represent one or more polyether groups represented _{by the formula: -CkH2kO-(C2H4O ) p ( C3H6O ) q ( C4H8O ) r} -Y;
Y is 100 mol % H group or 75 mol % or more H group and 25 mol % or less other group selected from C1-C4 alkyl or acetyl group;
m, n, k, p, q, and r are numbers that satisfy the following conditions:
12≦(m+n)≦230,
10≦m,
2≦n,
n≦m,
3≦k≦4,
p, q, and r each represent a formula weight of the polyether group portion represented by X in the range of 1,400 to 4,000;
The ratio Z, which is {the sum of the formula weights of the oxypropylene group portion represented by (C ₃ H ₆ O)q and the oxybutylene group portion represented by (C ₄ H ₈ O)r}/{the sum of the formula weights of the oxyethylene group portion represented by (C ₂ H ₄ O)p)}, is
This is a number that satisfies the condition (51/49)≦Z≦(95/5).
However, in the formula, a polyether group having a structure where p is 1 or less and q=r=0 is excluded.
The present invention relates to a method for improving the hydrophobicity of polyurethane foam, which is characterized by using a foam booster containing a silicone polyether copolymer represented by the following formula:

The present invention can provide a foam enhancer that has excellent compatibility with premix systems for on-site foaming spray foam formulations that use a large amount of water and a polyol for flexible polyurethane foam and are suitable for building insulation applications, and that can form large-volume foams suitable for building insulation applications with a small amount of use, and that can produce foams with fine cell structures and significantly improve the hydrophobicity of the resulting foams. It can also provide a premix liquid for polyurethane spray foam systems and a composition for forming polyurethane spray foams that contain the foam enhancer.

The present invention also provides a flexible polyurethane foam with improved hydrophobicity obtained from the polyurethane spray foam forming composition and its uses, in particular, the flexible polyurethane foam having low emission/low VOC properties, and a heat insulating material or sound absorbing material made of the same.

Furthermore, the present invention provides a method for significantly improving the hydrophobicity of polyurethane foam by utilizing the foam enhancer to improve the hydrophobicity of the foam in the production of polyurethane foam other than water-blown polyurethane spray foam.

The foam enhancer of the present invention is excellent in quality and environmental compatibility, and can be manufactured at a lower cost than foam stabilizers for soft slab foams that are currently being repurposed for water-foamed spray foams. Therefore, the present invention allows foam stabilizer manufacturers to have the option of supplying large quantities to the market at lower prices than before, while premix and foam system manufacturers can provide end customers and the market with premix liquids for polyurethane spray foam systems and compositions for forming polyurethane spray foams that are excellent in cost-in-use and characteristics, and both parties have greater freedom to contribute to the healthy development of society and industry while pursuing fair profits.

[Silicone polyether copolymer and foam booster containing same]
First, the silicone polyether copolymer, which is the main component of the foam booster of the present invention, will be described in detail. As described above, the present invention is based on the unexpected discovery that the hydrophobicity of urethane foam is significantly improved by selecting the chemical structure of the silicone polyether copolymer, and the discovery that the silicone polyether copolymer is particularly suitable for use in a water-blown polyurethane spray foam system having a specific structure, and the structure of the silicone polyether copolymer is one of the characteristic structures of the present invention.

More specifically, the silicone polyether copolymer according to the present invention is represented by the following general formula (1).
General formula (1):

In general formula (1), each X independently represents one or more _polyether groups represented _{by the} formula: _-CkH2kO- ( _C2H4O ) _p ( _{C3H6O ) q} ( _C4H8O ) _r -Y;
Y is 100 mol % H group or is composed of 75 mol % or more H group and 25 mol % or less other group selected from C1-C4 alkyl or acetyl group;
m, n, k, p, q, and r are numbers that satisfy the following conditions:
12≦(m+n)≦230,
10≦m,
2≦n,
n≦m,
3≦k≦4,
p, q, and r each represent a formula weight of the polyether group portion represented by X in the range of 1,400 to 4,000;
The ratio Z, which is {the sum of the formula weights of the oxypropylene group portion represented by (C ₃ H ₆ O)q and the oxybutylene group portion represented by (C ₄ H ₈ O)r}/{the sum of the formula weights of the oxyethylene group portion represented by (C ₂ H ₄ O)p)}, is
This is a number that satisfies the condition (51/49)≦Z≦(95/5).
However, in the formula, X does not include a polyether group having a structure where 1≦p and q=r=0. In other words, the polyether group portion represented by X in the formula may be a mixture of polyether chains having two or more different average chemical structures, but does not include a group in which the polyoxyalkylene portion is composed only of polyoxyethylene groups. This is because, as will be described later, if the proportion of the portion derived from the oxyethylene unit in the polyether portion in the present invention is high, the technical effect of the present invention cannot be achieved.

The formula weight is the sum of the products of atomic weights and the number of atoms based on a chemical formula or composition formula, but here it refers to the formula weights of the polyether group portion, oxypropylene group portion, and oxyethylene group portion represented by X, and their sum, calculated based on the average chemical structure (the structure identified by nuclear magnetic resonance analysis using mainly 13C and 1H as nuclei) of the unsaturated group-containing polyether compound that is the reaction raw material for the silicone polyether copolymer.

In the above general formula (1), R is preferably independently selected from an alkyl group having 1 to 10 carbon atoms, an aryl group, and an aralkyl group, and examples thereof include linear or branched alkyl groups such as methyl, ethyl, n-propyl, n-butyl, i-butyl, n-pentyl, i-pentyl, 2-methylbutyl, n-hexyl, and n-octyl; a phenyl group; a phenethyl group, and a phenylisopropyl group. From an industrial perspective, R is particularly preferably a methyl group.

In the general formula (1), X is a polyether group having a polyoxyalkylene structure bonded to a silicon atom, and is represented by the formula:
_{-CkH2kO- ( C2H4O} ) _{p ( C3H6O ) q ( C4H8O} ) _r -Y
Here, k is the number of carbon atoms in the alkylene group bonded to the silicon atom, and from the viewpoint of industrial practicality, 3≦k≦4, with k=3 being more preferred.

Y is a terminal group of a polyoxyalkylene structure, and is either 100 mol% H groups (hydrogen atoms) or 75 mol% or more H groups and 25 mol% or less other groups selected from C1-C4 alkyl or acetyl groups. Preferably, Y is 100 mol% hydrogen atoms.

In the polyether group portion represented by X, p, q, and r are the average numbers of oxyethylene units, oxypropylene units, and oxybutylene units constituting the polyoxyalkylene structure, the formula weight of the X group is within the range of 1,400 to 4,000, and the ratio Z of {the sum of the formula weights of the oxypropylene group portion represented by (C ₃ H ₆ O)q and the oxybutylene group portion represented by (C ₄ H ₈ O)r}/{the sum of the formula weights of the oxyethylene group portion represented by (C ₂ H ₄ O)p)} is
This is a number that satisfies the condition (51/49)≦Z≦(95/5).

Here, when the ratio value Z is more than (95/5), the hydrophobicity derived from the oxypropylene group portion represented by (C ₃ H ₆ O) q and the oxybutylene group portion represented by (C ₄ H ₈ O) r becomes excessive, and it becomes difficult for the silicone polyether copolymer to make the polyether polyol compatible with a large amount of water, and the premix liquid tends to be unstable and foamed. Conversely, when the ratio value Z is less than (51/49), that is, the number of oxyethylene units is equal to or higher than the sum of the oxypropylene unit and the oxybutylene unit, the compatibility with the polyol for flexible urethane foam used in the on-site foaming spray foam formulation for building insulation becomes insufficient, making it difficult to obtain a stable premix liquid, and the desired foaming effect cannot be obtained, and the technical effect of the present invention may not be achieved. The polyether group portion represented by X may be a mixture of two or more polyether chains with different average chemical structures, but does not contain a polyether group having a hydroxyl group at the end and consisting of only an oxyethylene portion. Such highly polar hydrophilic groups are unsuitable because they have poorer compatibility with the polyol.

More preferably, the X group does not contain an oxybutylene unit and has the formula:
_-C3H6O ( _C2H4O ) _{p ( C3H6O ) q -} H
The formula weight of the X group is within the range of 1500 to 2500, and the ratio Z satisfies the condition (54/46)≦Z≦(80/20).

The oxyethylene units, oxypropylene units, and oxybutylene units contained in the polyether group X may have a block type copolymer structure or a random type copolymer structure, but a random type structure is more preferable.

In addition, the alkylene group bonded to the silicon atom that has 3 to 4 carbon atoms, and the alkylene portion that constitutes the oxypropylene unit or oxybutylene unit, may be a straight-chain alkylene group or a branched isoalkylene group such as an isopropylene group or an isobutylene group.

In the above general formula (1), m and n are the degrees of polymerization of each siloxane unit of the side chain (Rake) type silicone polyether copolymer, and are numbers in the ranges of 12≦(m+n)≦230, 10≦m, 2≦n, and n≦m. In particular, numbers in the ranges of 40≦m≦90 and 2≦n≦8 are preferred.

By selecting the above structures (particularly the preferred structures), the silicone polyether copolymer according to the present invention has the following properties:
i) Excellent compatibility with polyols for flexible urethane foams, enabling the formation of a stable premix solution
ii) It has excellent foaming properties, and even a small amount can be used to form a large volume of foam (foam volume) at the construction site, making it cost-effective and efficient to use in construction applications.
iii) The resulting foam has a fine cell structure and is suitable for use as a heat insulating material, sound absorbing material, etc.
iv) Compared with conventional foam enhancers, it has a major advantage not available in the prior art of being able to significantly improve the hydrophobicity of polyurethane foams (particularly flexible polyurethane foams), and is also able to satisfy the requirement of low emission/low VOC, which has become increasingly important in recent years, particularly in construction applications.

Specifically, in the above-mentioned preferred silicone polyether copolymer, the ratio of the lipophilic portion derived from the oxypropylene unit or oxybutylene unit to the formula weight of the entire polyether portion is high, so that it has excellent compatibility with polyols for flexible polyurethane foams used in on-site foaming spray foam formulations for building insulation. This is therefore advantageous in obtaining desirable foam stabilization effects such as increased convenience due to improved stability of the premix liquid, and imparting a large foam volume and fine cell structure.

In addition, since the preferred silicone polyether copolymer has a low ratio of oxyethylene unit-derived portions relative to the formula weight of the entire polyether portion, it does not solidify even at low temperatures, does not become too viscous, and improves handling after production. Furthermore, when the preferred silicone polyether copolymer is used as a foam stabilizer for the spray foam, it can significantly improve the hydrophobicity of the resulting urethane foam in addition to providing a foam-enhancing effect.

[Synthesis of Silicone Polyether Copolymer]
Such silicone polyether copolymers can be synthesized by a known method in which a polyether compound having an alkenyl group at one end of the molecular chain is subjected to a hydrosilylation reaction with an organohydrogenpolysiloxane in the presence or absence of any solvent.

｛式中、Ｒは前記と同様の定義であり、ｍ，ｎは前記と同様の数である｝で表されるオルガノハイドロジェンポリシロキサン、
下記一般式（２）：
Ｃ_ｋＨ_２ｋ－１Ｏ－（Ｃ_２Ｈ_４Ｏ）_p（Ｃ_３Ｈ_６Ｏ）_q（Ｃ_４Ｈ_８Ｏ）_r－Ｙ
｛式中、ｋ、ｐ、ｑ及びｒは前記と同様の数であり、Ｙは前記と同様の定義であり、Ｃ_ｋＨ_２ｋ－１は炭素－炭素二重結合を有する直鎖または分岐鎖状のアルケニル基である｝で示される分子鎖の片末端にアルケニル基を有するポリエーテル化合物とのヒドロシリル化反応により得られた、シリコーンポリエーテル共重合体である。 Preferably, the silicone polyether copolymer according to the present invention has the following general formula (1H):

{wherein R is as defined above, and m and n are as defined above},
The following general formula (2):
C _k H _{2 k-1} O-(C ₂ H ₄ O) _p (C ₃ H ₆ O) _q (C ₄ H ₈ O) _r -Y
{wherein k, p, q and r are the same numbers as defined above, Y is defined as above, and C _k H _2k-1 is a straight-chain or branched-chain alkenyl group having a carbon-carbon double bond}, and is obtained by a hydrosilylation reaction with a polyether compound having an alkenyl group at one end of the molecular chain.

In this case, the oxyethylene unit, oxypropylene unit, and oxybutylene unit contained in the polyether compound represented by the general formula (2) may have a block type copolymer structure or a random type copolymer structure, but a random type structure is preferable. In addition, the silicone polyether copolymer according to the present invention can be obtained by reacting two or more different types of the polyether compounds with the organohydrogenpolysiloxane, but does not include a structure where 1≦p and q=r=0: that is, a polyether compound in which the polyoxyalkylene part is composed only of polyoxyethylene parts. The reason for this is that the polyether group having a hydroxyl group at the end and composed only of oxyethylene parts has too strong polarity, which inhibits compatibility with the polyol for soft urethane foam used in the formulation of on-site foaming spray foam for building insulation, making it difficult to obtain a stable premix liquid and impairing the desired foam-stabilizing effect.

When carrying out the above hydrosilylation reaction, the ratio of [the amount of carbon-carbon double bonds in the polyether compound/the amount of silicon-bonded hydrogen atoms in the organohydrogenpolysiloxane] can be exemplified as being in the range of 1.0 to 2.0. That is, when synthesizing the silicone polyether copolymer according to the present invention, it is preferable to use an excess amount of polyether compound. More specifically, the above ratio is preferably in the range of 1.05 to 1.75, and more preferably in the range of 1.20 to 1.60. The reason for this is that the terminal alkenyl groups of the polyether compound generally undergo internal rearrangement during the hydrosilylation reaction and are no longer involved in the reaction, so that in order to completely consume the silicon-bonded hydrogen atoms, it is necessary to make the molar ratio of the alkenyl groups in excess. Therefore, such a silicone polyether copolymer is generally obtained as a mixture of the silicone polyether copolymer product and unreacted polyether compound, and constitutes a foam enhancer having a hydrophobicity improving effect, which contains the silicone polyether copolymer represented by the general formula (1) according to the present invention.

Since these components have excellent compatibility with each other, the foam enhancer having a hydrophobicity improving effect containing the silicone polyether copolymer is usually obtained as a transparent or almost transparent homogeneous liquid. In industrial use, the polyether compound represented by the general formula (2) is usually produced by adding ethylene oxide and propylene oxide in the presence of an alkali catalyst to an unsaturated alcohol such as allyl alcohol or allyl glycol as a starting material, but depending on the level of water removal from the reaction system, it may contain diols at both ends as impurities. Therefore, such diols at both ends, such as a PEG/PPG copolymer, may be further contained in the foam enhancer according to the present invention.

During the hydrosilylation reaction, the progress of the reaction may be slowed down due to the influence of trace impurities originally contained in the polyether compound or the organohydrogenpolysiloxane, by-products due to deterioration over time, trace contaminants in the reaction apparatus, etc. In such cases, it is desirable to take appropriate measures such as adding a catalyst, raising the reaction temperature slightly higher than usual, extending the reaction time, or adding a reaction solvent to improve the compatibility between the raw materials, and to manage the process until the remaining Si-H groups in the reaction system are below the detection limit. It is known that the remaining Si-H groups may cause the generation of flammable hydrogen gas when the foam enhancer is mixed into a premix system, and that the remaining Si-H groups exceeding a certain amount deteriorate the foam stabilizing performance of silicone polyether copolymers generally used as foam stabilizers for urethane foams. Therefore, the remaining amount of Si-H groups is preferably about 30 wt. ppm or less of the foam enhancer, more preferably 10 wt. ppm or less, and particularly preferably 2.5 wt. ppm or less. Although silicone polyether copolymers that partially contain such trace amounts of Si-H groups are not literally represented by the above general formula (1), they are industrially essentially the same type and are included in the present invention.

Here, a reaction solvent is often not necessary, but when using a general organic solvent, it is preferable for industrial production to select from aromatic hydrocarbon solvents such as toluene and xylene, alcohol solvents such as isopropyl alcohol, and aliphatic saturated hydrocarbon solvents such as cyclohexane, n-heptane, and methylcyclohexane. In general, these highly volatile reaction solvents must be removed from the product system by stripping as soon as they have completed their role, such as when the hydrosilylation reaction is completed. Among these, toluene and xylene belong to the so-called BTX solvents and have been widely used in the production of silicone polyether copolymers used as foam stabilizers for some time. However, it is difficult to eliminate the BTX solvents, especially on a production scale, and therefore they cannot meet the needs of the current polyurethane industry, which requires strict BTX management. Therefore, when necessary, it is desirable to select and use an appropriate one from isopropyl alcohol or a saturated hydrocarbon solvent having an average carbon atom number in the range of 6 to 11, taking into consideration costs, safety, convenience during production, etc.

Specific examples of saturated hydrocarbon solvents having an average carbon atom number in the range of 6 to 11 include methylcyclohexane, n-heptane, heptane mixture, heptane (commercial grade), isooctane, 2,2,4-trimethylpentane, octane mixture, ethylcyclohexane, dimethylcyclohexane, n-hexane, isohexane, hexane mixture, cyclohexane, 2-methylpentane, 2-methylheptane, 3-methylheptane, Isopar E (C7-C9 saturated hydrocarbon mixture), Isopar C (C7-C8 saturated hydrocarbon mixture), IP solvent 1016 (C6-C9 saturated hydrocarbon mixture), Isopar G (C10-C11 saturated hydrocarbon mixture), etc. Among these, C7 saturated hydrocarbons represented by methylcyclohexane, n-heptane, heptane mixture, and heptane (commercial grade) are preferred.

The foam enhancer of the present invention may further contain an optional diluent h') polyalkylene glycol or a derivative thereof that is liquid at 25°C. By using such component h'), it may be possible to adjust the viscosity of the foam enhancer of the present invention and improve the convenience and ease of handling during use without adversely affecting its function as a foam stabilizer or surfactant. Furthermore, component h') may be used in addition to the foam enhancer for the purpose of adjusting the hydroxyl value in the polyurethane foam-forming composition, i.e., for the purpose of controlling various physical properties such as the crosslink density and strength of the polyurethane foam.

The catalyst for the hydrosilylation reaction is not limited to a specific one as long as it can promote the hydrosilylation reaction. Many metals and compounds have been known as hydrosilylation reaction catalysts, and an appropriate one can be selected from them and used in the production of component e) of the present invention. Specific examples of hydrosilylation reaction catalysts include finely divided platinum adsorbed on a silica fine powder or carbon powder carrier, chloroplatinic acid, alcohol-modified chloroplatinic acid, Speyer's catalyst, olefin complex of chloroplatinic acid, coordination compound of chloroplatinic acid and vinylsiloxane, Karstadt catalyst, platinum black, palladium, and rhodium catalyst. These catalysts can be dissolved or dispersed in toluene, xylene, ligand compounds of the catalyst, alcohols, other suitable polar solvents, polyethers or diluents as reaction raw materials, according to a standard method, and then added to the reaction system.

The amount of the hydrosilylation catalyst used is not particularly limited as long as it is an effective amount and promotes the synthesis reaction of the silicone polyether copolymer, which is the main component of the foam booster of the present invention. Specifically, the amount of metal atoms in the catalyst is 0.5 to 100 ppm by mass, preferably 3 to 30 ppm by mass of platinum metal atoms, relative to the sum of the organohydrogenpolysiloxane represented by the general formula (1H) and the polyether compound having an alkenyl group at one end of the molecular chain represented by the general formula (2) (total being 100 mass%). If the content of the hydrosilylation catalyst is less than the lower limit of the above range, the addition reaction may be insufficient, and if it exceeds the upper limit of the above range, it is uneconomical and may have an adverse effect on the transparency, such as coloring, of the obtained composition of the present invention.

The conditions for the hydrosilylation reaction can be selected arbitrarily depending on the type of raw material and the presence or absence of a solvent. For example, the reaction can be completed by adding a small amount of an antioxidant such as tocopherol (vitamin E) and heating and stirring for a certain period of time under an inert gas atmosphere such as nitrogen at room temperature to 120°C, preferably 50 to 100°C. The antioxidant may be added after completion of hydrosilylation. The reaction time can be selected depending on the reaction scale, the amount of catalyst used, and the reaction temperature, and is generally in the range of several minutes to several hours. The reaction may be performed under reduced pressure for the purpose of improving quality and productivity, and not only a batch process but also a known semi-continuous or continuous production process can be applied.

The end point of the hydrosilylation reaction can be confirmed by the disappearance of Si-H bond absorption by infrared spectroscopy (IR) or by the disappearance of hydrogen gas generation using the alkaline decomposition gas generation method described below. The amount of hydrogen gas generated can also be determined by analyzing the silicon-bonded hydrogen atoms (Si-H) in the organohydrogenpolysiloxane, the reaction raw material, using the same method.

The alkaline decomposition gas generation method involves reacting a solution of a sample dissolved in toluene or IPA with a mixed solution of 28.5% caustic potassium in ethanol/water at room temperature, collecting the hydrogen gas generated in a collection tube and measuring its volume.

In addition, since the silicone polyether copolymer, which is the main component of the foam booster according to the present invention, has a structure modified by a polyether group having a terminal hydroxyl group, it is important to suppress the side reactions during the hydrosilylation reaction: dehydrogenation reaction and acetal formation. When using chloroplatinic acid or a solution thereof as a catalyst, it is advisable to add an appropriate amount of a buffer agent, such as an alkali metal salt of a carboxylate such as potassium acetate, potassium propionate, or sodium acetate, to the reaction system before starting the main reaction. These can be added to the reaction system as a solid (powder), dissolved or dispersed in a polar solvent such as methanol and then added to the reaction system, or dissolved or dispersed in a polyether compound having an alkenyl group at one end of the molecular chain represented by general formula (2) in advance, to exert their effects. In general, when these side reactions occur, the reaction system thickens, and in severe cases, it may even gel. The use of a reaction solvent is effective in alleviating such a situation. The buffer is preferably added before the start of the hydrosilylation reaction (main reaction), but even if it is added after the main reaction is complete, it is effective to some extent in suppressing the acetal formation reaction during the subsequent stripping process or after production. However, care must be taken when adding too much buffer, as this can slow down the progress of the main reaction or easily induce another side reaction, starting with scission of the silicone main chain, during the stripping process. The optimal amount of buffer to add is the amount that is just enough to neutralize the amount of acid in the system, or a slightly larger amount.

The foam booster of the present invention may be gradually oxidized by oxygen in the air and may be deteriorated. To prevent this, it is possible and preferable to add antioxidants such as phenols, hydroquinones, benzoquinones, aromatic amines, or vitamins to increase the oxidation stability. As such antioxidants, for example, in addition to the aforementioned vitamin E, BHT (2,6-di-t-butyl-p-cresol), vitamin C, etc. may be used. However, from the viewpoint of reducing emissions from polyurethane foam, it is important to select vitamin E or other high molecular weight type antioxidants. In this case, the amount of antioxidant added is in the range of 10 to 1000 ppm, preferably 50 to 500 ppm, by mass relative to component e).

[Reduction of low molecular weight siloxane]
The foam booster according to the present invention preferably contains 5000 ppm (by weight) or less of low molecular weight siloxanes having 20 or less silicon atoms, and more preferably 2000 ppm (by weight) or less. If this value exceeds 5000 ppm, when the foam booster is used as a foam stabilizer for polyurethane foam, it may contaminate the surrounding materials in the area where the polyurethane foam is installed, and cause contact failure in electric and electronic devices. Such low molecular weight siloxanes include cyclic and linear ones, such as cyclic dimethylsiloxanes represented by the formula [(CH3)2SiO]n (wherein n is an integer of 3 to 10), and linear dimethylsiloxane oligomers represented by the formula CH3[(CH3)2SiO]mSi(CH3)3 (wherein m is an integer of 1 to 10), and also those in which some of the methyl groups are replaced by other organic groups. More specific examples of such low molecular weight siloxanes include octamethyltetrasiloxane, decamethylpentacyclosiloxane, and dimethylsiloxane oligomers blocked with trimethylsiloxy groups at both ends. The content of such low molecular weight siloxanes can be measured by analysis, for example, using a gas chromatography analyzer. There is no limitation on the method for reducing low molecular weight siloxanes, but since this is usually done industrially by stripping, it is desirable to purify the organohydrogenpolysiloxane, which is the raw material for the silicone polyether copolymer/foam booster of the present invention, in advance to remove low molecular weight siloxanes. Alternatively, low molecular weight siloxanes may be removed during or after the hydrosilylation reaction.

[Water-blown polyurethane spray foam system]
The foam booster containing the silicone polyether copolymer of the present invention is applied to water-blown polyurethane spray foam systems comprising the following a) to d):
a) one or more polyether polyols having an average number of hydroxyl groups in the molecule of 2 to 4, having repeating units composed of oxypropylene groups, and having a number average molecular weight in the range of 1,000 to 6,000;
b) polyisocyanates,
c) a curing catalyst;
d) Water as a blowing agent. The sum of the polyether polyol (component a) and other polyol components in the system is in the range of 10 to 40 parts by mass.

Furthermore, the water-blown polyurethane spray foam system may contain a') at least one polyol component other than the polyether polyol component a). In this case, the blowing agent d) water is added in an amount of 10 to 40 parts by mass per 100 parts by mass of the sum (=total amount) of the components a) and a').

Furthermore, the above water-blown polyurethane spray foam system may optionally contain, within the scope of its practical application and without impairing the technical effect of the present invention, f) nonionic surfactants (including organic surfactants and emulsifiers that do not fall under the category of the silicone polyether copolymer of the present invention), g) flame retardants, and h) other additives, such as foam stabilizers for urethane foam other than the foam enhancer of the present invention, diluents, chain extenders, crosslinking agents, minor amounts of non-aqueous blowing agents, cell openers, fillers, reinforcing agents, pigments, dyes, colorants, antioxidants, anti-ozonants, UV stabilizers, antistatic agents, bactericides, and antibacterial agents. These components are explained below.

[a) Polyether polyol]
The component a) used in the present invention is one or more polyether polyols having an average number of hydroxyl groups of 2 to 4, an oxypropylene repeating unit, and a number average molecular weight of 1000 to 6000. Such polyols can be used in general soft urethane foams such as soft slab foams, and are produced by addition polymerization of alkylene oxide to water or a polyhydric alcohol having an average of 2 to 4 hydroxyl groups per molecule as a starting material. Examples of such polyoxyalkylene polyols include polyoxyalkylene polyols containing alkylene oxide adducts such as water, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, butylene glycol, pentanediol, hexanediol, neopentyl glycol, glycerin, trimethylolpropane, ammonia, triethanolamine, triisopropanolamine, pentaerythritol, diglycerin, ethylenediamine, and aromatic diamines. The alkylene oxide used in the production of polyoxyalkylene polyols usually has 2 to 4 carbon atoms, and propylene oxide and a mixture of propylene oxide and ethylene oxide are suitable. These polyols may be used alone or in combination of two or more. For example, a mixture of a bifunctional substance and a tri- or tetrafunctional substance and/or a mixture of substances with different molecular weights or different chemical compositions may be used. From the viewpoint of imparting low emission properties to polyurethane foams, it is important to select additives (e.g. antioxidants and stabilizers) contained in polyols that are non-volatile and have a high molecular weight.

Specific examples of useful polyether polyols as component a) include Voranol-3010, Voranol 3137, V230-056 Polyol (Dow Chemical Company), ARCOL Polyol 16-56, ARCOL 200 Polyol 16-56 (Arco Chimecal Co.), NIAX Polyol 16-56 (A.C. West Virginia Polyol Company), Desmophen PU20WB01, Desmophen 7186, Desmophen VPPU 20 WB 01 (BAYER), and polypropylene glycol-based polyether polyol No. 33 (Sanyo Chemical Industries, Ltd.), EO/PO triol of 3500 molecular weight containing 10% internal EO, polyether polyol with a hydroxyl value of 56 obtained by addition polymerization with EO/PO = 16/84 (weight ratio) using glycerin as the starting material, polyoxyalkylene triol {EO/PO = 12/88 (weight ratio), hydroxyl value 48}, polyether polyol with a hydroxyl value of 46 obtained by addition polymerization with EO/PO = 14/86 (weight ratio) using glycerin as the starting material, polyether polyol with a hydroxyl value of 46 obtained by addition polymerization with EO/PO = 16/84 (weight ratio) using glycerin as the starting material, PO/EO adduct of glycerin (hydroxyl value 33), etc.

[a') Polyol other than the above a)]
Suitable examples of polyols that can be used in combination with the component a) in the present invention as necessary include halogenated polyether polyols and brominated polyols (dibromoneopentyl glycol, brominated pentaerythritol, and polymerized polyols of epichlorohydrin and brominated polyols) that are excellent in flame retardancy. For the purpose of improving the curing reaction rate and adjusting the cell size, relatively low molecular weight and high functionality polyether polyols: alkylene oxide adducts to polyhydric alcohols and polyhydric amines having an average number of 3 to 8 hydroxyl groups and a number average molecular weight of 250 to 1000 are also preferred. For example, sorbitol, sucrose, lactose, α-methyl glucoside, α-hydroxyalkyl glucoside and other sugars, diethylene triamine, glycerin, trimethylolpropane, triethanolamine, pentaerythritol, ethylenediamine, and adducts of propylene oxide and/or ethylene oxide to aromatic diamines are included.

In addition, as long as the effects of the present invention are not impaired, polyester polyols produced by dehydration condensation of carboxylic acids such as adipic acid and phthalic acid with polyhydric alcohols such as ethylene glycol, 1,4-butanediol, and 1,6-hexanediol, polyether polyols with a high content of primary hydroxyl groups and an average molecular weight of about 5,000 to 7,000 that are typically used for HR foams, and polymer polyols in which polymer particles are dispersed by copolymerizing acrylonitrile, styrene, etc. in polyether polyols may be appropriately selected and used in combination.

[b) Polyisocyanate]
As the polyisocyanate, it is preferable to select a low-volatility or non-volatile organic polyisocyanate, taking into consideration the safety of workers and the surrounding environment, assuming that the polyisocyanate will be used in spray applications, particularly in the case of on-site foaming.

The commercially advantageous materials for component b) are MDI (diphenylmethane diisocyanate), 4,4'-diphenylmethane diisocyanate, 4,2'-diphenylmethane diisocyanate, polymeric MDI (polymethylene polyphenyl polyisocyanate), and crude MDI. In addition, as the isocyanate group-containing prepolymer, a prepolymer of MDI produced by reacting MDI with a polyol, a prepolymer of TDI produced by reacting TDI with a polyol, a prepolymer produced by reacting other aromatic or aliphatic polyisocyanates with a polyol, a uretonimine-modified polyisocyanate and a prepolymer thereof, etc. can also be used. Note that a derivative of the above polyisocyanate may be selected as component b).

From the viewpoint of imparting low emission characteristics to polyurethane foam, it is preferable to select the above-mentioned low-volatile or non-volatile organic polyisocyanate. On the other hand, when the foam is sprayed into a mold for an insulating panel or the like in a factory using automated work equipment and then heat cured, toluene diisocyanate (TDI) may be used in addition to the above-mentioned low-volatile or non-volatile organic polyisocyanate, after ensuring the safety of the working environment with local exhaust equipment, etc. TDI comes in two types, 2,4 and 2,6 isomers, and a mixture of 2,4/2,6 = 80/20 is usually distributed, so this may be used. The amount of polyisocyanate in the formulation relative to the amount of other materials is represented by the "isocyanate index". The "isocyanate index" is the value obtained by dividing the actual amount of polyisocyanate used by the stoichiometric amount of polyisocyanate required to react with all active hydrogen in the reaction mixture and multiplying the result by 100.

Because the polyurethane spray foam system of the present invention uses a large amount of water, the preferred range of the isocyanate index for component b) is different from the range for general polyurethane foams and is generally within the range of 30 to 80.

From the viewpoint of the use of the foam enhancer in the present invention, in the water-blown polyurethane spray foam system to which it is applied, it is particularly preferred that the polyisocyanate is a component selected from MDI (diphenylmethane diisocyanate), polymeric MDI (polymethylene polyphenyl polyisocyanate), crude MDI, isocyanate group-containing prepolymers, and derivatives thereof, and that the blowing agent (d)) of the system is water as the main blowing agent, more preferably substantially water alone, or water alone without any other blowing agent. In this case, it is more preferred that the isocyanate index of component b) is in the range of 20 to 80, more preferably 30 to 70.

[c) Urethane catalyst]
Metal catalysts and tertiary amines are generally used as catalysts for producing polyurethane resins. Tertiary amines promote the reaction of polyol and organic polyisocyanate to generate urethane bonds, and also promote the reaction of water and organic polyisocyanate to generate carbon dioxide gas, so they are widely used in the formation of various types of urethane foam. On the other hand, metal catalysts, such as tin catalysts, are more often used in the non-foaming urethane field because they have high catalytic activity for promoting urethane reaction and are highly practical, but even in the formulation of general soft slab foam, tin catalysts are used in combination with amine catalysts. In addition, nickel catalysts are mainly used in the formulation of mechanical froth foam.

The polyurethane spray foam system of the present invention uses a large amount of water, so it generates more heat of reaction than general soft foams, and therefore the reaction rate is also high. Therefore, it is usually sufficient to use an amine catalyst. Amine catalysts may be used alone or in combination of two or more types depending on the purpose of adjusting the reaction rate and foaming state. Examples of such amine catalysts include tertiary amine urethane catalysts such as dimethylethanolamine, dimethylaminoethoxyethanol, triethylenediamine, bis(2-dimethylaminoethyl)ether, N,N,N',N'-tetramethylhexamethylenediamine, and N,N',N',N''-pentamethyldiethylenetriamine, imidazole derivatives, delayed-acting tertiary amine catalysts, general-type tertiary amine catalysts, low-emission tertiary amine catalysts, non-emission tertiary amine catalysts, and DABCO (registered trademark) catalyst from Air Products. The use of low-emission tertiary amine catalysts in polyurethane foams is also useful. From the viewpoint of imparting emission properties, it is preferable to use a reactive amine catalyst. If necessary, a metal catalyst may be used in combination. Examples of these include nickel acetoacetonate, iron acetoacetonate, tin-based catalysts, bismuth-based catalysts, zinc-based catalysts, titanium-based catalysts, aluminum complexes, zirconium complexes, potassium octylate, potassium acetate, sodium acetate, sodium octylate, metal oxide particles having solid acid sites on the surface, and quaternary ammonium carboxylates. The amount of component c) added is usually 1 to 5 parts by weight per 100 parts by weight of the total polyol.

[d) Water as a blowing agent]
The polyurethane spray foam system according to the present invention forms a low-density, lightweight, soft polyurethane foam for thermal insulation or sound absorption, and is typically a 100-fold expansion (referring to a high expansion ratio such that, when the density of the polyurethane mixed liquid before foaming is assumed to be 1.0 g/cm3, the density of the foam after foaming is 0.01 g/cm3) formulation using water as the main blowing agent. Therefore, the number of parts of water added per 100 parts of the sum of the polyether polyol and other polyol components, which is component a) in the system, must be within the range of 10 to 40 parts, preferably within the range of 15 to 35 parts, and particularly preferably within the range of 15 to 25 parts.

As the water, purified water, pure water, distilled water, ion-exchanged water, tap water, clean water, etc. can be suitably used. In the case of on-site foaming spraying, it is preferable that the foaming agent is substantially only water, and it is particularly preferable that water is the only foaming agent, that is, water is the only foaming agent. If an expensive other foaming agent is used in combination, the open cell structure of the foam will cause gas to escape, which will not only impair the technical effect of the present invention, but will also be disadvantageous in terms of cost and may result in a waste of the effect of the invention. For this reason, in terms of convenience and cost, it is preferable that component d) is water at 95% by mass or more, more preferably 99% by mass or more, and even more preferably in the range of 99 to 100% by mass. The fact that water, which can be easily and cheaply procured at construction sites, etc., can be used as the foaming agent as it is, is one of the commercial and technical advantages of the foam enhancer and the like according to the present invention.

On the other hand, when the foam is sprayed into molds for insulation panels or the like in a factory using automated equipment and then heat cured, flame-retardant blowing agents such as hydrofluorocarbons HFC-245fa and HFC-134a, and hydrofluoroolefins HFO and HCFO may be used in combination. If these expensive gases do not leak out of the molds filled with the foam, they will help improve insulation.

[f) Nonionic surfactant]
Component f) is one of the optional components of the polyurethane spray foam system of the present invention, and its main purpose is to stabilize the premix liquid for the polyurethane spray foam system of the present invention. The nonionic surfactant of component f) is a nonionic organic surfactant or emulsifier that does not contain a silicon atom in its molecular structure. The above silicone polyether copolymer and foam boosters containing it are excluded from the scope of component f), and non-silicone (hereinafter referred to as "organic") surfactants or emulsifiers that do not contain a silicon atom in their molecular structure are particularly preferred.

The addition of a nonionic organic surfactant capable of improving the cloud point of the system is effective for ensuring the storage stability of the premix liquid over time and at a temperature. Since it is necessary to act as a compatibilizer between the component a) (polyether polyol) and the component d) (water) according to the present invention, a nonionic emulsifier with a high HLB (water solubility) is preferred, and polyoxyethylene alkylphenyl ethers such as POE nonylphenyl ether and POE octylphenyl ether, POE fatty alcohol ether, POE synthetic alcohol ether, POE branched alcohol ether, and POE secondary alcohol ether can be used. The number of moles of oxyethylene added can usually be in the high range of 2 to 100, but from the viewpoint of water solubility, 7 moles or more is preferred, and from the viewpoint of ease of availability and handling, 30 moles or less is preferred. Particularly preferred are POE (9-20) nonylphenyl ether and POE (9-20) octylphenyl ether. The preferred amount of component f) used is 5 to 30 parts by weight per 100 parts by weight of the total amount of polyol. If the amount is less than 5 parts, polyols with different polarities or polyols and water cannot be made compatible, making it difficult to obtain a homogeneous premix liquid; if the amount is more than 30 parts, the compatibility of the polyol components becomes too high, making it difficult for interconnection (cell opening) to occur, and foam shrinkage is likely to occur.

[g) Flame retardant]
The g) component is one of the optional components of the polyurethane spray foam system according to the present invention, and the flame retardant used in the present invention is a flame retardant component other than the flame retardant polyol contained in the a'), for example, phosphoric esters such as trimethyl phosphate, triethyl phosphate, trischloroethyl phosphate, and trischloropropyl phosphate. In a formulation that does not use a flame retardant polyol, the amount used is preferably 40 to 80 parts by weight per 100 parts by weight of the total polyol. If it is less than 40 parts by weight, the flame retardant effect may be insufficient. If it exceeds 80 parts by weight, the compatibility of the polyol component may be too high, making it difficult to form open cells. A particularly preferred amount is 50 to 70 parts by weight. On the other hand, in a formulation in which 15 to 35 parts by weight of the flame retardant polyol is blended out of the total polyol (100 parts by weight), the amount used of the g) component is preferably 20 to 40 parts by weight. The flame retardant g) can also be mixed with a polyisocyanate component to form a urethane foam. These flame retardants reduce the viscosity of the urethane mixture, making it easier to form a uniform foam by spraying, and also act as a plasticizer for the polyurethane resin, contributing to improved adhesion of the foam to the substrate.

[h) Optional components]
The component h) may be any component known in the art, such as a foam stabilizer for urethane foam other than the foam booster of the present invention, a diluent, a chain extender, a crosslinking agent, a secondary amount of a non-aqueous blowing agent, a cell opener, a filler, a reinforcing agent, a pigment, a dye, a colorant, an antioxidant, an anti-ozonant, an ultraviolet stabilizer, an antistatic agent, a bactericide and an antibacterial agent, and may be included within the range of their normal content as long as the technical effect of the present invention is not impaired. From the viewpoint of imparting low emission properties, it is important in the formulation design of a polyurethane foam-forming composition to confirm that even these optional components are materials composed only of components that do not cause migration or release due to volatilization from the foam, and to incorporate them into the foam formulation.

For example, as a foam stabilizer for urethane foam other than the foam enhancer of the present invention, a general foam stabilizer for soft slab foam may be used in combination, as long as it does not impair the effects of the present invention. For example, L-520 (Si-O-C type silicone polyether copolymer) first commercialized by Union Carbide Corporation, VORASURF DC198 Additive, DC5950 Additive, DC5943 Additive, DC5160 Additive, DC5900 Additive, DC5933 Additive, DC5982 Additive, DC5986 Additive, DC5987 Additive, DC5990 Additive (Si-C type silicone polyether copolymer) sold by The Dow Chemical Company, and SRX 280A, SRX 294A, SRX 298, SH 190 (Si-C type silicone polyether copolymer) sold by Dow Toray Industries, Inc., and the like can be mentioned. In addition, in a formulation in which a relatively low molecular weight and highly functional polyether polyol is used in combination as a'), in order to accommodate a more highly polar system, it is possible to use an appropriate amount of a silicone foam stabilizer for rigid foam in combination within a range that does not impair the effects of the present invention. Furthermore, silicone foam stabilizers for general HR foams and silicone foam stabilizers for microcellular foams may act as cell opening agents in the system of the present invention, so they may be used in appropriate amounts as necessary.

The optional component h) crosslinker or chain extender may contain a polyhydroxyl-terminated compound having 2 to 8 hydroxyl groups per molecule and a molecular weight of 62 to 500. Crosslinkers having 3 to 8 hydroxyl groups include glycerin, trimethylolpropane, pentaerythritol, mannitol, sorbitol, and the like. Examples of useful chain extenders having two hydroxyl groups include dipropylene glycol, tripropylene glycol, propylene glycol, diethylene glycol, triethylene glycol, 1,4-butanediol, ethylene glycol, 2,3-butanediol, 2-methyl-1,3-propanediol, 1,2-propanediol, 1,3-propanediol, and neopentyl glycol, and the like. Diethanolamine and monoethanolamine can also be used. These compounds may be treated as diluents. Other suitable diluents include polyalkylene glycols or derivatives thereof that are liquid at 25°C.

Optional h) component may also include fillers such as inorganic fillers or combinations of fillers. Fillers include those for density modification, improvement of mechanical or physical performance such as sound absorption, flame retardancy or other benefits including improved economics such as calcium carbonate or other fillers to reduce the cost of foam production, aluminum hydroxide or other flame retardant fillers, barium sulfate or other high density fillers used for sound absorption, microspheres of materials such as glass or polymers to further reduce foam density. High aspect ratio fillers or reinforcing agents used to modify mechanical performance such as foam stiffness or flexibility module include man-made fibers such as crushed glass or graphite fibers; natural mineral fibers such as wollastonite; natural animal fibers such as wool or plant fibers such as cotton; man-made plate-like fibers such as crushed glass; natural mineral plate-like fillers such as mica. Any of the pigments, dyes, and colorants that may be added. Additionally, the present invention contemplates the use of anti-ozonants, antioxidants; heat or heat-oxygen degradation inhibitors, UV stabilizers, UV absorbers, or any other additives which, when added to the foam-forming composition, avoid or inhibit the heat, light, and/or chemical degradation of the resulting foam. Also contemplated for use herein are any of the known and conventional antistatic agents, germicides, antimicrobial agents, and gas fade inhibitors.

[Premix liquid]
The premix liquid for a polyurethane spray foam system according to the present invention contains at least a) the polyether polyol, c) a urethane catalyst, d) a blowing agent which is water, the amount of which is 10 to 40 parts by mass per 100 parts by mass of the sum of the polyether polyol which is component a) in the system and other polyol components, and e) a foam enhancer having a hydrophobicity improving effect which contains the silicone polyether copolymer.

Furthermore, the premix liquid for the polyurethane spray foam system according to the present invention preferably further contains the above-mentioned f) nonionic surfactant, in particular an organic nonionic surfactant. The premix liquid for the polyurethane spray foam system according to the present invention may have a color derived from the base material, but usually has the properties of a transparent homogeneous liquid.

[Polyurethane spray foam forming composition]
The polyurethane spray foam forming composition according to the present invention contains the above-mentioned components a), b), c), d), and e), and may further contain, optionally, one or more selected from the above-mentioned components a') and f). The composition may further contain g) a flame retardant, and may optionally contain h) other additives. The types and amounts of each component are as described in the polyurethane spray foam system.

An example of the formulation of the polyurethane spray foam forming composition according to the present invention is shown below. Here, the following component a) satisfies the requirement of "one or more polyether polyols having an average number of hydroxyl groups in the molecule of 2 to 4, having repeating units consisting of oxypropylene groups, and having a number average molecular weight in the range of 1000 to 6000." In addition, the concentration of isocyanate groups in the following component b) is in the range of 30.5 to 32.0 wt. %.
Formulation 1 :
a) 100 parts by weight of polypropylene glycol-based polyether polyol (Sanyo Chemical No. 33) c) 2 parts by weight of DABCO 33LV (triethylenediamine, Sigma Aldrich) e) 1 part by weight of foam enhancer or comparative foam stabilizer d) 25 parts by weight of water g) 60 parts by weight of trischloropropyl phosphate (Daihachi Chemical, flame retardant TMCPP) b) 207 parts by weight of Millionate MR-100 (Tosoh, Polymeric MDI)

The polyurethane spray foam forming composition according to the present invention can be suitably used in the formation of soft polyurethane foams, and can meet the needs of the current polyurethane industry, which requires strict VOC (Volatile Organic Compound) control or emission control. More specifically, the content of the low molecular weight siloxanes having 20 or less silicon atoms in the foam enhancer can be easily suppressed to 5000 ppm (weight) or less, 2000 ppm (weight) or less, or 1000 ppm (weight) or less, and the amount used as a foam enhancer is small, so that the VOCs and their emissions derived from these volatile siloxanes can be almost completely suppressed in the finally obtained polyurethane foam. Note that if the content of these components in the foam enhancer exceeds 5000 ppm, when the foam enhancer is used as a foam stabilizer for polyurethane foam, it is undesirable because it may contaminate the surrounding members at the location where the polyurethane foam is installed and cause contact failure in electric and electronic devices.

The flexible polyurethane foam obtained by curing the polyurethane spray foam forming composition according to the present invention is not limited in its applications, but can be suitably used as a building material, particularly as a heat insulating material or sound absorbing material, cured by foaming on site.

The flexible polyurethane foam of the present invention has a stable premix liquid, excellent handling and workability, and excellent foaming properties, and even a small amount can be used to form a large volume of foam (= foam volume) at the manufacturing site of a building, making it cost-effective and efficient to use in buildings, etc. The foam obtained has a fine cell structure and is suitable for use as a heat insulating material/sound absorbing material, etc., and compared to the use of conventional foam enhancers, it has the major advantage of being able to significantly improve the hydrophobicity of polyurethane foam (particularly flexible polyurethane foam), which is not available in conventional technologies, and can meet the requirements for low emission/low VOC, which have become increasingly important in recent years, especially in building applications.

The present invention will be explained in more detail below with reference to examples and comparative examples, but the present invention is not limited to these.

The procedure for evaluating the performance of the foam enhancer of the present invention will be explained below in the following order: A: premix compatibility test, B: urethane foam formation, C: evaluation of urethane foam volume/cell structure, and D: urethane foam water absorption test.

[A: Premix compatibility test]
A compatibility test of the foam booster of the present invention and the comparative foam stabilizer in a premix liquid was carried out according to the following procedure.
A 1.50 g of a) polyether polyol and the desired ratios of d) water, c) urethane catalyst, e) foam booster or comparative foam stabilizer are charged to a 100 mL glass bottle.
A2. Using a saw blade-equipped disc-type dispersing mixer, mix the above contents for 1 minute to homogenize.
A3. Stopper the glass bottle and leave it at room temperature overnight to remove bubbles.
A4. Visually check the appearance (transparency) of the mixed liquid and record it.

[B: Formation of urethane foam]
B1. The premix liquid prepared in A, g) flame retardant, and b) polyisocyanate are charged into a 200 mL plastic cup in a predetermined ratio so that the total weight is 20 g, and immediately stirred with a saw-blade disk-type dispersing mixer at 3500 rpm for 7 seconds.
B2. Stop the agitation of the mixer and immediately pour the obtained homogeneously mixed polyurethane spray foam forming composition into a 1 L plastic cup and allow it to foam naturally. The time from the start to the end of pouring is fixed at 8 seconds.
B3. Allow the resulting foam to stand overnight at room temperature.

[C: Evaluation of urethane foam volume/cell structure]
C1. The plastic cup foam prepared in B is cut into upper and lower halves using an electric cutter.
C2. Record the foam height (in mm) and the homogeneity of the cell structure of the foam cross-section.

[D: Water absorption test of urethane foam]
D1. The foam piece obtained in C is further cut into pieces using an electric cutter to prepare a rectangular test piece measuring 6.5 cm long x 6.5 cm wide x 4 cm high. Here, this test piece is taken from the center of the foam in the plastic cup prepared in B.
D2. Measure and record the weight of the test piece.
D3. Prepare a water bath.
D4. Immerse the lower half of the test piece in a water bath for 2 hours, then remove it, measure and record its weight.
D5. Calculate and record the water absorption (wt%) of the test piece.

In the first round of testing, the following two groups were compared as comparative foam stabilizers. These are mainly composed of commercially available foam stabilizers. In the composition formulas representing the silicone polyether copolymers that are the main components of these foam stabilizers, Me ₃ SiO group (or Me ₃ Si group) is represented as "M ", Me ₂ SiO group is represented as "D ", Me ₂ HSiO group is represented as " ^MH ", MeHSiO group is represented as " ^DH ", and units in which one of the methyl groups in M and D is modified with some kind of substituent (modified group that is * or **) are represented as M ^* and D ^* , etc. In addition, (EO) represents an oxyethylene group, (PO) represents an oxypropylene group, Me group represents a methyl group, and Ac group represents an acetyl group.
[Comparative foam stabilizer (first round)]
・Group R: 9 types of foam stabilizers for rigid urethane foam ・Group F: 3 types of foam stabilizers for flexible slab foam

The identification numbers of the comparative foam stabilizers belonging to Group R and the average composition formulas of the main components are shown below. For the sake of simplicity, the formula is expressed as if (EO) and (PO) are bonded in blocks, but in reality it is a random addition structure.
Comparative foam stabilizer R1: M ^* D ₂₅ D ^* ₁ M ^* , ^* =-C ₃ H ₆ O(EO) ₁₅ (PO) ₅ -H
Comparative foam stabilizer R2: MD ₄₃ D ^* _6.8 M, ^* = -C ₃ H ₆ O (EO) ₂₆ (PO) ₆ -CH ₃
Comparative foam stabilizer R3: MD ₅₀ D ^* ₇ M, ^* = -C ₃ H ₆ O (EO) ₁₁ (PO) _3.5 -H
Comparative foam stabilizer R4: M ^* D ₁₈ D ^* ₃ M ^* , ^* =-C ₃ H ₆ O(EO) ₁₅ (PO) ₅ -CH ₃
Comparative foam stabilizer R5: M ^* D ₂₅ D ^* ₁ M ^* , ^* = _{-C3H6O (} EO) ₂₄ (PO) ₆ - _CH3
Comparative foam stabilizer R6: MD ₃₄ D ^* _5.7 M, ^* = -C ₃ H ₆ O (EO) ₁₂ (PO) ₂ -H
Comparative foam stabilizer R7: MD ₃₄ D ^* _5.7 M, ^* = -C ₃ H ₆ O (EO) ₁₁ (PO) _3.5 -H
Comparative foam stabilizer R8: M ^* D ₄₂ D ^* ₅ M ^* , ^* = _{-C3H6O (} EO) ₁₇ (PO) ₇ - _CH3
Comparative foam stabilizer R9: MD ₃₇ D ^* _3.4 D ^** _2.1 M, ^* = -C ₃ H ₆ O (EO) ₁₁ (PO) _3.5 -CH ₃ , ^** = -C ₃ H ₆ O (EO) ₁₁ (PO) _3.5 -H

The identification numbers of the comparative foam stabilizers belonging to Group F and the average composition formula of the main components are shown below. For the sake of simplicity, the formula is expressed as if (EO) and (PO) are bonded in blocks, but in reality it is a random addition structure.
Comparative foam stabilizer F1: MD ₅₀ D ^* _5.9 M, ^* = -C ₃ H ₆ O (EO) ₂₂ (PO) ₂₂ -CH ₃
Comparative foam stabilizer F2: MD ₃₃ D ^* _2.8 M, ^* = -C ₃ H ₆ O (EO) ₂₂ (PO) ₂₂ -CH ₃
Comparative foam stabilizer F3: MD ₅₃ D ^* ₃ M, ^* = -C ₃ H ₆ O (EO) ₂₂ (PO) ₂₂ -COCH ₃

The structural elements of the 12 comparative foam stabilizers are summarized below.
[Table 1]: Structure of comparative foam stabilizer (first round)

The performance evaluation results of the 12 comparative foam stabilizers are summarized below. Note that data for which no data was collected or recorded is indicated as "-".
[Table 2]: Relationship between performance and structure of comparative foam stabilizers (first round)

These results show that when the polyether end group Y of the silicone foam stabilizer has a structure mainly composed of H, compatibility with the premix liquid is insufficient and it is difficult to obtain a transparent appearance. In addition, because the premix liquid appearance was transparent for all foams with excellent foam height (volume), it was found that a structural design with excellent compatibility with the premix is important. Next, it was found that, in general, lower values were obtained for the water absorption rate of the foam when using foam stabilizers for soft slabs (Group F) rather than foam stabilizers for rigid foams (Group R).

However, since there is a demand for foams with low water absorption while achieving the same level of foam volume as when the above-mentioned foam stabilizer for soft slabs is used, improvements on the conventional technology were necessary. Therefore, 12 new silicone polyether copolymers with different structures were synthesized and their performance was evaluated by comparing them with the above-mentioned R8 and F3. The details are as follows.

[Synthesis of Copolymers for Examples/Comparative Examples (Second Round)]
The synthesis procedure for one silicone polyether copolymer (foam enhancer of the present invention) of the embodiment is shown below for reference. The other embodiment samples and comparative example samples (comparative foam stabilizers) have different structures or combinations of the main raw material organohydrogenpolysiloxane and one-terminal allyl group-containing polyether, but were synthesized in a procedure generally similar to that of this example. In the composition formulas representing these silicone polyether copolymers, Me ₃ SiO group (or Me ₃ Si group) is represented as "M ", Me ₂ SiO group is represented as "D ", Me ₂ HSiO group is represented as " ^MH ", MeHSiO group is represented as " ^DH ", and the units in which the methyl group in M and D is modified by some substituent are represented as M ^* and D ^* , etc. In addition, (EO) represents an oxyethylene group, (PO) represents an oxypropylene group, Me group represents a methyl group, and Ac group represents an acetyl group.

Example 1: Production of foam booster with identification number SI-1 _139.68 g of ^{organohydrogenpolysiloxane} raw material represented by the average composition formula _MD53DH3M and having an analytical value of 0.072 mass% hydrogen group concentration bonded to silicon atoms, 310.32 g of one-terminated allyl polyether raw material represented by the average composition formula _CH2 =CH- _CH2 -O( _C2H4O ) ₉ ( _C3H6O ) ₂₂ -H and having an analytical value of 0.45 mmol/g unsaturated group concentration and _28.4 mg-KOH/g hydroxyl value, and 135 g IPA ( _isopropyl alcohol) were charged into a 1 L flask, and while stirring under nitrogen flow, the temperature of the oil bath was set to 85°C and heating was started. The molar ratio of allyl/SiH in this reaction system was 1.4. When the temperature of the flask contents was 45-50°C, 244 ppm (equivalent to 10 ppm as platinum) of an IPA solution (Pt concentration 0.4 wt%) of platinum-divinyldisiloxane complex (Karlstadt catalyst) was added, and the reaction liquid became transparent after 18 minutes. The temperature of the flask contents was maintained at 80°C and the reaction was carried out for 80 minutes. Next, 1 g of the reaction liquid was sampled and confirmed by the alkali decomposition gas generation method, and the reaction was found to be complete. The temperature of the oil bath was set to 125°C, the nitrogen flow rate was increased, and distillation of IPA was started at normal pressure. When the distillation rate slowed down, the IPA in the receiver was once discarded, and the pressure in the system was gradually reduced to 30 mmHg, while paying attention to foaming and bumping. After that, the temperature of the flask contents was maintained at 110-125°C and the pressure was 10 mmHg or less for 75 minutes, and further volatile matter was removed. After that, heating was stopped and the flask was allowed to cool to 95°C or less, and the pressure was restored.

This resulted in a pale _yellow -brown, transparent _, homogeneous liquid containing _a silicone polyether copolymer represented by the average composition formula _MD53D ^* _3M { ^* =- _C3H6O ( _C2H4O ) ₉ ( _C3H6O ) ₂₂ -H}. Note that for simplicity, the polyoxyethylene groups and polyoxypropylene groups are shown as being block-bonded, but in reality, this is a random addition structure.
Foam enhancer SI-1: MD ₅₃ D ^* ₃ M, ^* = -C ₃ H ₆ O (EO) ₉ (PO) ₂₂ -H

<Examples 2 to 4> Structures of foam boosters with identification numbers SI-2 to SI-4 The identification numbers of the example samples and the average composition formulas of the main components are shown below. For the sake of simplicity, the formula is shown as if (EO) and (PO) are bonded in blocks, but in reality it is a random addition structure.
Foam enhancer SI-2: MD ₅₃ D ^* ₃ M, ^* = -C ₃ H ₆ O (EO) ₁₈ (PO) ₁₆ -H
Foam enhancer SI-3: MD ₅₄ D ^* _6.5 M, ^* = -C ₃ H ₆ O (EO) ₁₈ (PO) ₁₆ -H
Foam enhancer SI-4: MD ₈₃ D ^* _7.7 M, ^* = -C ₃ H ₆ O (EO) ₁₈ (PO) ₁₆ -H

<Comparative Example 1 to Comparative Example 8> Identification numbers SR-1 to SR-8
The identification numbers of the comparative sample and the average composition formula of the main component are shown below. For the sake of simplicity, the formula is expressed as if (EO) and (PO) are bonded in blocks, but in reality it is a random addition structure.
Comparative foam stabilizer SR-1: MD ₅₃ D ^* ₃ M, ^* = -C ₃ H ₆ O (EO) ₃₀ (PO) ₁₀ -H
Comparative foam stabilizer SR-2: MD ₅₄ D ^* _6.5 M, ^* = -C ₃ H ₆ O (EO) ₁₅ (PO) ₅ -H
Comparative foam stabilizer SR-3: MD ₅₄ D ^* _6.5 M, ^* = -C ₃ H ₆ O (EO) ₂₁ (PO) ₉ -H
Comparative foam stabilizer SR-4: MD ₅₄ D ^* _6.5 M, ^* = -C ₃ H ₆ O (EO) ₃₀ (PO) ₁₀ -H
Comparative foam stabilizer SR-5: MD ₈₃ D ^* _7.7 M, ^* = -C ₃ H ₆ O (EO) ₂₁ (PO) ₉ -H
Comparative foam stabilizer SR-6: MD ₈₃ D ^* _7.7 M, ^* = -C ₃ H ₆ O (EO) ₃₀ (PO) ₁₀ -H
Comparative foam stabilizer SR-7: MD ₅₄ D ^* _6.5 M, ^* = -C ₃ H ₆ O (EO) ₂₁ (PO) ₉ -CH ₃
Comparative foam stabilizer SR-8: MD ₈₃ D ^* _7.7 M, ^* = -C ₃ H ₆ O (EO) ₂₁ (PO) ₉ -CH ₃

The structural elements of the 12 copolymer samples for the Examples and Comparative Examples are summarized below, including R8 and F3 for comparison.
[Table 3]: Structure of prototype sample (second round)

The performance evaluation results of 12 copolymer samples for Examples and Comparative Examples are summarized below. The results are indicated with "-" if no data was collected or recorded. For comparison, the above-mentioned R8 and F3 are also included.
[Table 4]: Relationship between performance and structure of prototype samples (second round)

The above results show that even if the polyether end group Y of the silicone foam stabilizer has a structure mainly composed of H, when the ratio Z is large (here, it has a long PO-rich polyether chain), it is possible to obtain a foam with excellent compatibility with the premix system, large volume, good cell structure, and low water absorption. In other words, it has been found that by selecting the specific chemical structure of the present invention for the silicone polyether copolymer used as a foam stabilizer for urethane foam, it is possible to improve the hydrophobicity of the urethane foam itself. On the other hand, when the polyether end group Y of the silicone foam stabilizer has a structure capped with Me or Ac, etc., it has the characteristic of having excellent compatibility with the premix even if the ratio Z is small, but it is clear that the water absorption of the obtained foam is high and does not meet market needs.

In particular, foam enhancers SI-1 to SI-4 of the present invention have the advantage that they can be produced more cheaply than the foam stabilizers for flexible slab foam currently being used for spray foam systems, because there is no need to cap the hydroxyl group portion of the raw material, the one-terminated allyl polyether. Nevertheless, as shown in Table 4 above, they are superior to F3 in terms of the overall balance of performance. Therefore, the foam enhancers of the present invention will make a great contribution to the healthy development of society and industry.

[Confirmation of low emission properties]
The foam boosters SI-1 to SI-3 of the present invention were analyzed for volatile cyclic siloxanes (D4 to D6) by headspace GC according to the following procedure.
E1. Approximately 1 g of sample was weighed into a 20 mL vial and sealed.
E2. The vial was heated at 150° C. for 30 minutes, and then 1 mL of the headspace was injected into GC using a headspace sampler and measured.

The results of the GC analysis are summarized in Table 5. The content of each cyclic siloxane component was significantly below 0.10% (1000 ppm), confirming that there is no problem from the viewpoint of low emission.
Table 5: Volatile siloxane content of the foam booster of the present invention (unit: wt. ppm)

The following is a formulation example of a composition for forming a polyurethane spray foam for insulation blown at 100 times the amount of water, which is suitable for use with the foam booster of the present invention.
[Table 6]: Composition for forming flexible polyurethane heat insulation spray foam (foamed with 100 times the amount of water)
In addition, component a) in the table below satisfies the requirement of "one or more kinds of polyether polyols having an average number of hydroxyl groups in the molecule of 2 to 4, having repeating units consisting of oxypropylene groups, and having a number average molecular weight in the range of 1000 to 6000." In addition, the calculated isocyanate index of formulations 2 and 3 in the table below is about 30.

Claims (8)

a) one or more polyether polyols having an average number of hydroxyl groups in the molecule of 2 to 4, having repeating units composed of oxypropylene groups, and having a number average molecular weight in the range of 1,000 to 6,000;
a') at least one polyol component other than the polyether polyol component a);
b) polyisocyanates,
c) a curing catalyst;
d) A blowing agent which is water. The sum of the polyether polyol which is component a) in the system and other polyol components is in the range of 15 to 35 parts by mass per 100 parts by mass.
e) General formula (1):

In the formula, each R independently represents a monovalent hydrocarbon group having 1 to 16 carbon atoms selected from an alkyl, aryl, or aralkyl group;
X's each independently represent one or more polyether groups represented _{by the formula: -CkH2kO-(C2H4O ) p ( C3H6O ) q ( C4H8O ) r} -Y;
Y is 100 mol % H group or is composed of 75 mol % or more H group and 25 mol % or less other group selected from C1-C4 alkyl or acetyl group;
m, n, k, p, q, and r are numbers that satisfy the following conditions:
12≦(m+n)≦230,
10≦m,
2≦n,
n≦m,
3≦k≦4,
p, q, and r each represent a formula weight of the polyether group portion represented by X in the range of 1,400 to 4,000;
The ratio Z, which is {the sum of the formula weights of the oxypropylene group portion represented by (C ₃ H ₆ O)q and the oxybutylene group portion represented by (C ₄ H ₈ O)r}/{the sum of the formula weights of the oxyethylene group portion represented by (C ₂ H ₄ O)p)}, is
This is a number that satisfies the condition (51/49)≦Z≦(95/5).
However, in the formula, a polyether group having a structure where p is 1 or less and q=r=0 is excluded.
A foam booster comprising a silicone polyether copolymer represented by the formula:
f) One or more nonionic surfactants selected from POE (9-20) nonyl phenyl ether and POE (9-20) octyl phenyl ether. The sum of the polyether polyol, which is component a), and other polyol components in the system is in the range of 5 to 30 parts by mass per 100 parts by mass.
A premix for polyurethane spray foam systems comprising: In the general formula (1),
X's each independently represent the formula: -C ₃ H ₆ O(C ₂ H ₄ O) _p (C ₃ H ₆ O) _q -H
is one or more kinds of polyether groups represented by
The formula weight of the polyether group portion represented by X is in the range of 1500 to 2500, and
The ratio Z satisfies the condition (54/46)≦Z≦(80/20).
10. The premix liquid for a polyurethane spray foam system according to claim 1. In the general formula (1), R is a methyl group, and m and n satisfy the conditions of 40≦m≦90 and 2≦n≦8.
A premix liquid for a polyurethane spray foam system according to claim 1 or 2. The polyisocyanate b) is a component selected from the group consisting of diphenylmethane diisocyanate (MDI), polymeric MDI (polymethylene polyphenyl polyisocyanate), crude MDI, isocyanate group-containing prepolymers, and derivatives thereof; and
The blowing agent of the system is d) water alone.
A premix liquid for a polyurethane spray foam system according to any one of claims 1 to 3. A polyurethane foam-forming composition comprising the premix liquid for a polyurethane spray foam system according to any one of claims 1 to 4 . The polyurethane foam-forming composition of claim 5 , further comprising g) a flame retardant. A flexible polyurethane foam obtained by curing the polyurethane foam-forming composition according to claim 5 or 6 . A heat insulating or sound absorbing material comprising the flexible polyurethane foam according to claim 7 .