JP2010247532A - Polyurethane foam laminate and method for manufacturing the same, and gasket - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyurethane foam laminate, in which a fire retardant does not bleed out, and which is flexible, is difficult to be damaged, and is excellent in appearance, and a method for manufacturing the same, and a gasket. <P>SOLUTION: The polyurethane foam laminate 2 having a resin film layer 22 and a foam layer 21 in which the density is 100-280 kg/m<SP>3</SP>is prepared by mixing a foam raw material containing polyisocyanate, polyol, and the fire retardant, and a gas and stirring, to produce a gas-liquid mixture, thereafter, supplying the gas-liquid mixture 21a on a resin film 22a, and heating to reaction-cure the foam raw material. The fire retardant contains a metal hydroxide powder and a liquid fire retardant, and the contents of them are respectively 20-60 pts.mass and 5-20 pts.mass relative to 100 pts.mass polyol. Further, the gasket formed using the laminate is used for water stop or the like between chassis members such as a cell-phone. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a polyurethane foam laminate, a method for producing the same, and a gasket. More specifically, the present invention includes a polyurethane foam layer containing a specific flame retardant, the flame retardant does not bleed out, is flexible, hardly scratched, and has excellent appearance, and a resin film layer. The present invention relates to a polyurethane foam laminate having excellent flame retardancy, a method for producing the same, and a gasket comprising the polyurethane foam laminate and having excellent flame retardancy and sealability.

  2. Description of the Related Art Conventionally, in electronic devices such as mobile communication devices such as mobile phones, digital cameras, and car navigation systems, gaskets are disposed on the peripheral edge of a housing in order to suppress the intrusion of moisture and dust into the inside. In particular, electronic devices and precision devices used in harsh environments such as high-temperature atmospheres, as well as highly heat-generating electronic devices and precision devices, are difficult to pass the HBF standard, which is a flame retardant standard prescribed in UL94. It must be flammable. In order to impart such flame retardancy, (1) halogenated flame retardants such as organic bromine compounds and organic chlorine compounds, (2) antimony trioxide, (3) organophosphorus compounds, (4) metal hydroxides (For example, refer patent document 1) The gasket using the resin foam which mix | blended various flame retardants, such as is proposed.

However, the various flame retardants described above have the following problems.
(1) A halogen-based flame retardant is not preferable because a halide having a large environmental load is generated during combustion.
(2) Antimony trioxide is not preferable because it has been confirmed to have a large environmental burden and is harmful.
(3) Organophosphorus compounds are often in a liquid state, and there is a concern that foam physical properties deteriorate when blended in a large amount, and that they bleed out and migrate to a housing or the like. In the case of a gasket formed by integrating a resin film and a resin foam, for example, in a flame retardant test prescribed in UL94, the resin film as a base material is prevented from shrinking and curling the test piece to the foam side. As a result, there is a problem that the HBF standard is not passed.
(4) Metallic compounds such as aluminum hydroxide and magnesium hydroxide have little impact on the environment and the human body as described above, and can be used as a safe gasket. For example, flame retardants that pass HBF standards In order to obtain a gasket having a property, it is necessary to mix it in a large amount with a resin foam. However, in the mechanical floss method, the addition of powder to the foam material leads to thickening, especially when producing low-density resin foam, the thickening becomes significant, and the fine cell structure inherent in the resin foam by the mechanical floss method is inherent. There is a problem that formation is difficult, the surface of the foam is rough, and so-called cell roughening occurs.

JP-A-2005-171102 JP 2007-44972 A

  Patent Document 1 discloses a flame retardant sealing material having a specific density and 25 to 50 parts by weight of a metal hydroxide that is a flame retardant mixed with 100 parts by weight of a polyol. In Patent Document 1, it is described that when the density is low, the contact area with air is increased, and the flame retardancy is reduced. Further, in this flame-retardant sealing material, it has been described that when the metal hydroxide exceeds 50 parts by weight, it becomes hard or brittleness is exhibited, causing a problem in sealing properties. The problem when blended is described. Furthermore, as a method of dealing with this problem, by using a polyol as a dilution medium for the foam stabilizer, the foam stabilizer is taken into the polyurethane molecule, and volatilization of the foam stabilizer, which is an impediment to flame retardancy, is achieved. A method to prevent is described.

  Patent Document 2 discloses an article including a base film and a polyurethane foam layer formed on the base film, and a seal used for a display such as a mobile phone as the article. The member is illustrated. Furthermore, it is described that an arbitrary additive may be added to the polyurethane foam mixture, and a flame retardant is exemplified as the additive.

  The present invention has been made in view of the above-described conventional situation, and the polyurethane foam layer and the resin film are excellent in appearance without causing the flame retardant to bleed out, being flexible and hardly scratched. The present invention relates to a polyurethane foam laminate having a layer and excellent in flame retardancy, a method for producing the same, and a gasket comprising the polyurethane foam laminate and excellent in flame retardancy and sealability.

The present invention is as follows.
1. A foam raw material containing a polyisocyanate, a polyol and a flame retardant is mixed with a gas to form a gas-liquid mixture. Then, the gas-liquid mixture is supplied onto a resin film, and then the gas-liquid mixture is heated. In the polyurethane foam laminate having a resin film layer made of the resin film and a foam layer made of the produced polyurethane foam, obtained by reacting the foam raw material,
The flame retardant contained in the foam raw material includes a metal hydroxide powder and a liquid flame retardant, and when the polyol is 100 parts by mass, the metal hydroxide powder is 20 to 60 parts by mass. The liquid flame retardant is 5 to 20 parts by mass, and
A polyurethane foam laminate, wherein the foam layer has a density of 100 to 280 kg / m ³ .
2. 2. The polyurethane foam laminate according to 1 above, wherein the liquid flame retardant is a phosphorus flame retardant.
3. 3. The polyurethane foam laminate according to 1 or 2 above, wherein the metal hydroxide powder has an average particle size of 10 to 100 μm.
4). 4. The polyurethane foam laminate according to any one of 1 to 3, wherein the resin film layer contains polyethylene terephthalate, and the thickness of the resin film layer is 25 to 125 μm.
5). The polyurethane foam laminate according to any one of 1 to 4 above, wherein the foam layer has an average cell diameter of 50 to 300 µm.
6). 6. The polyurethane foam laminate according to any one of 1 to 5, wherein the foam layer has a skin layer on a surface opposite to a surface laminated on the resin film layer.
7. The polyurethane foam laminate according to any one of 1 to 6 above, wherein the load when compressed by 40% is 0.002 to 0.02 MPa.
8). 8. The polyurethane foam laminate according to any one of 1 to 7 above, wherein the compression residual strain when compressed by 50% at a temperature of 70 ° C. is 10.0% or less.
9. A foam raw material containing a polyisocyanate, a polyol and a flame retardant is mixed with a gas to form a gas-liquid mixture. Then, the gas-liquid mixture is supplied onto a resin film, and then the gas-liquid mixture is heated. And reacting the foam raw material to produce a polyurethane foam laminate having a resin film layer comprising the resin film and a foam layer comprising a polyurethane foam produced by reaction curing of the foam raw material.
The flame retardant contained in the foam raw material includes a metal hydroxide powder and a liquid flame retardant, and when the polyol is 100 parts by mass, the metal hydroxide powder is 20 to 60 parts by mass. The liquid flame retardant is 5 to 20 parts by mass, and
The method for producing a polyurethane foam laminate, wherein the foam layer has a density of 100 to 280 kg / m ³ .
10. 9. A gasket comprising the polyurethane foam laminate according to any one of 1 to 8 above.
11. 11. The gasket according to 10 above, wherein the thickness is 0.4 to 1.5 mm.

According to the polyurethane foam laminate of the present invention, as the flame retardant, each contains a predetermined amount of metal hydroxide powder and a liquid flame retardant, the flame retardant does not bleed out, is flexible, and It is provided with a foam layer that is hardly scratched and has excellent appearance, and a resin film layer. As a whole, it is excellent in flexibility and suitable as a sealing material such as a gasket having excellent flame retardancy, which is disposed in a device used in a severe environment such as a high-temperature atmosphere, a device having heat generation properties, etc. is there.
When the liquid flame retardant is a phosphorus flame retardant, the combination of the phosphorus flame retardant and the metal hydroxide powder prevents the flame retardant from bleeding out on the surface of the foam layer, and a predetermined density is obtained. It has a flexible foam layer and has excellent flame retardancy.
When the said resin film layer contains a polyethylene terephthalate and the thickness of this resin film layer is 25-125 micrometers, a polyurethane foam laminated body is excellent in shape stability. And when this polyurethane foam laminated body is used as a gasket, the sealing in the peripheral part of the two members which comprise the housing | casing etc. of an apparatus can be made perfect. That is, the adhesion between the peripheral edge and the resin film layer is excellent.
When the average cell diameter of the foam layer is 50 to 300 μm, the compressive residual strain in the foam layer is small, and excellent sealability and the like can be obtained over a long period of time when used as a gasket.
In addition, when the foam layer has a skin layer on the surface opposite to the surface laminated on the resin film layer, the sealing at the peripheral portions of the two members constituting the housing of the device is completely performed. Can be. That is, as with the adhesiveness on the resin film layer side, the foam layer side can also be closely attached to the peripheral portion, so that when used as a gasket for a casing of a mobile phone or the like, a better sealing property or the like Is obtained.
When the 40% compression load in the polyurethane foam laminate of the present invention is 0.002 to 0.02 MPa, it is sufficiently flexible. And when manufacturing gaskets for casings of cellular phones, etc. by processing such as punching with a punching die for this polyurethane foam laminate, the foam layer is damaged or chipped at the periphery of the processed part, etc. There is nothing to do. In addition, when the polyurethane foam laminate of the present invention is used as a gasket or the like, excellent sealing properties and the like can be obtained.
In the polyurethane foam laminate of the present invention, when the compression residual strain at 50 ° C. and 50% compression is 10.0% or less, it is particularly high temperature as a gasket or the like for a casing of a mobile phone or the like. When used in such a severe environment, excellent sealing properties and the like are maintained over a longer period of time.
When the average cell diameter of the foam layer is 50 to 300 μm, a polyurethane foam laminate having excellent physical properties such as a small compressive residual strain can be obtained.

According to the method for producing a polyurethane foam laminate of the present invention, the flame retardant does not bleed out, does not cause cell roughening, has a foam layer having a good appearance, and a resin film layer, and is flame retardant. A polyurethane foam laminate having excellent properties can be produced.
Moreover, the average cell diameter of a foam layer can be made small compared with the normal soft slab polyurethane foam with the same density manufactured using water or a foaming agent.
When the average particle diameter of the metal hydroxide powder contained in the foam raw material is 10 to 100 μm, the foam raw material and the gas-liquid mixture do not excessively thicken and are easy to handle. In addition, when forming a gas-liquid mixture using this foam raw material and gas, the mixing of both is easy, and the homogeneous gas-liquid mixture is efficiently produced while suppressing sedimentation of the metal hydroxide powder. Can be prepared.
When the resin film contains polyethylene terephthalate, the resin film has sufficient strength, heat resistance, etc., and therefore, when the gas-liquid mixture is heated, the foam layer and the resin film are not easily stretched. A polyurethane foam laminate having excellent layer adhesion can be produced stably.

According to the gasket of the present invention, it is excellent in flame retardancy, flexibility, and sealing properties, the foam layer is hardly damaged, and the work when disposed between housing members such as a cellular phone is easy. In addition, mobile phones and the like tend to be thin, and when a device is completed using a conventional gasket, the housing member may be warped. However, when the gasket of the present invention is used, warpage does not occur and an apparatus having excellent sealing properties can be obtained.
In addition, when the thickness of the gasket is 0.4 to 1.5 mm, the work for disposing between the casing members in a small device such as a mobile phone is easy. In addition, it is not necessary to compress the gasket excessively when it is disposed. Therefore, excellent sealing properties and the like are maintained over a long period.

It is a schematic diagram for demonstrating the manufacturing process of the polyurethane foam laminated body of this invention. It is a perspective view of an example of the gasket which consists of a foam layer and a resin film layer.

  11; Oaks mixer, 12; Roll coater, 13; Heating furnace, 2; Polyurethane foam laminate, 21; Foam layer, 21a; Gas-liquid mixture, 21b; Uncured layer, 22; Resin film layer, 22a resin film, 3 A release paper or a release-treated resin film, 101; a gasket, 101; a foam layer, 102; a resin film layer.

The present invention will be described in detail below.
1. Polyurethane foam laminate and method for producing the same The polyurethane foam laminate of the present invention is obtained by mixing a foam raw material containing a polyisocyanate, a polyol and a flame retardant with a gas to form a gas-liquid mixture. A liquid mixture is supplied onto a resin film, and then the gas-liquid mixture is heated to have a resin film layer made of a resin film obtained by reacting a foam raw material and a foam layer made of a produced polyurethane foam. It is a laminate. And the flame retardant contained in the said foam raw material contains a metal hydroxide and a liquid flame retardant, The content is 20-60 mass parts and 5-20 mass, respectively, when a polyol is 100 mass parts. Part. Moreover, the density of the foam layer to be formed is 100 to 280 kg / m ³ .

1-1. Foam raw material The foam raw material is a composition containing a polyisocyanate, a polyol, and a flame retardant, and includes other components described later as necessary.
The said polyisocyanate is not specifically limited, The polyisocyanate conventionally used for manufacture of a polyurethane foam can be used. As this polyisocyanate, 4,4′-diphenylmethane diisocyanate (MDI), crude MDI, tolylene diisocyanate and the like are usually used. In addition to these, 1,6-hexamethylene diisocyanate, 1,5-naphthalene diisocyanate, paraphenylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, 4,4′- Aromatic or aliphatic polyisocyanates such as dicyclohexylmethane diisocyanate, m-xylene diisocyanate, hexamethylene diisocyanate, hydrogenated MDI, and isophorone diisocyanate, prepolymer type polyisocyanate, and the like can also be used. Although the said polyisocyanate may use 2 or more types together, often only 1 type is used.
The polyisocyanate is blended so that the isocyanate index is preferably 0.8 to 1.2, particularly preferably 0.9 to 1.1.

The said polyol is not specifically limited, The polyol conventionally used for manufacture of a polyurethane foam can be used. As this polyol, polyether polyol, polyester polyol, polyether ester polyol obtained by copolymerizing polyether polyol and polyester polyol, and the like can be used. In addition, a polymer polyol can be used in combination for the purpose of forming a foam layer having sufficient tensile strength and the like. This polymer polyol is, for example, a polyether polyol containing an ethylenically unsaturated compound such as acrylonitrile, styrene, or methyl methacrylate in terms of solid content, preferably 10 to 40% by mass, more preferably 15 to 30% by mass, and graft polymerization. Polyol.
The average molecular weight of the polyol is preferably 400 to 5000, more preferably 800 to 4000.
The said polyol may be used only 1 type and can also use 2 or more types together.

As the flame retardant, a metal hydroxide powder and a liquid flame retardant are used in combination.
As said metal hydroxide powder, the powder which consists of aluminum hydroxide, magnesium hydroxide, calcium hydroxide, etc. is mentioned. Only one metal hydroxide powder may be used, or two or more metal hydroxide powders may be used in combination. Of these, aluminum hydroxide powder having three hydroxyl groups and a decomposition point as low as about 200 ° C. is preferable. When this aluminum hydroxide powder is used, particularly excellent flame retardancy can be imparted by the combined use with a liquid flame retardant.
Furthermore, the average particle diameter of the metal hydroxide powder is preferably 10 to 100 μm, particularly preferably 25 to 75 μm. When the average particle diameter of the metal hydroxide powder is 10 to 100 μm, the foam raw material and the gas-liquid mixture do not excessively thicken and are easy to handle. In addition, when forming a gas-liquid mixture using this foam raw material and gas, the mixing of both is easy, and the homogeneous gas-liquid mixture is efficiently produced while suppressing sedimentation of the metal hydroxide powder. Can be prepared. The average particle size is a value measured by a particle size distribution measuring device.

The liquid flame retardant is not particularly limited, but is preferably a liquid flame retardant at 25 ° C. When this liquid flame retardant is used, the viscosity of the foam raw material can be reduced. And the mixing efficiency of foam raw material and gas improves, and it can be set as a homogeneous gas-liquid mixture. As a result, a homogeneous foam layer having excellent flame retardant dispersibility can be formed.
Examples of the liquid flame retardant include a halogen-containing flame retardant containing a halogen atom such as a chlorine atom and a bromine atom, and a halogen-free flame retardant containing no halogen. From the viewpoint of environmental burden, a halogen-free flame retardant is preferred. The halogen-free flame retardant is preferably a phosphorus-based flame retardant, and examples of the phosphorus-based flame retardant include organic phosphorus compounds such as phosphate ester-based flame retardants and polyphosphoric acid-based flame retardants. Of these, phosphate ester flame retardants are preferred. These organophosphorus compounds may be used alone or in combination of two or more.

  Phosphate ester flame retardants include trimethyl phosphate, triethyl phosphate, tributyl phosphate, triisobutyl phosphate, triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, cresyl diphenyl phosphate, cresyl di-2,6-xylenyl phosphate Etc.

By using a foam raw material having a specific content of the above two kinds of flame retardants, a polyurethane foam laminate having a foam layer excellent in flame retardancy can be obtained.
The content of the metal hydroxide powder contained in the foam raw material is 20 to 60 parts by mass, preferably 30 to 60 parts by mass, particularly preferably 30 to 50 parts by mass, when the polyol is 100 parts by mass. It is. When the content of the metal hydroxide powder is 20 to 60 parts by mass, the foam raw material and the gas-liquid mixture are not excessively thickened, so that a foam layer in which cell roughness is suppressed can be formed. The content of the metal hydroxide powder is usually set in consideration of physical properties such as a compression load and compression residual strain of the polyurethane foam laminate.

  Further, the content of the liquid flame retardant contained in the foam raw material is 5 to 20 parts by mass, preferably 7 to 18 parts by mass, particularly preferably 10 to 15 parts by mass, when the polyol is 100 parts by mass. It is. When the content of the liquid flame retardant is 5 to 20 parts by mass, thickening of the foam raw material and the gas-liquid mixture is sufficiently suppressed, and a foam layer in which the liquid flame retardant does not bleed out can be formed. In addition, flame retardancy and flexibility can be maintained high. The content of the liquid flame retardant is usually set in consideration of physical properties such as a compression load and a compression residual strain of the polyurethane foam laminate.

  In addition to polyisocyanate, polyol and flame retardant, the foam raw material contains a catalyst, a foam stabilizer, a crosslinking agent and the like.

Examples of the catalyst include organic tin compounds such as stannous octoate, dibutyltin diacetate and dibutyltin dilaurate, organic zinc compounds such as zinc octylate, organic nickel compounds such as nickel acetylacetoate and nickel diacetylacetoate, iron acetylacetate Organic iron compounds such as ate, alkali metal or alkaline earth metal alkoxides such as sodium acetate, metal catalysts such as phenoxide, triethylamine, triethylenediamine, N-methylmorpholine dimethylaminomethylphenol, imidazole, 1,8-diazabicyclo [5 4.0] tertiary amine catalysts such as undecene, organic acid salts and the like. Of these, organotin compounds are preferred. In addition, only 1 type may be used for a catalyst and it can also use 2 or more types together.
The content of the catalyst contained in the foam raw material depends on the type, the formation conditions of the foam layer, and the like, but preferably 0.05 to 2.0 parts by mass, particularly preferably 100 parts by mass of the polyol. Is 0.05 to 1.0 part by mass.

As the foam stabilizer, a silicone foam stabilizer is usually used. Examples of the silicone foam stabilizer include dimethylsiloxane compounds, polyether dimethylsiloxane compounds, and phenylmethylsiloxane compounds. These may be used alone or in combination of two or more. These compounds may be compounds having an organic functional group. In the present invention, a polyether dimethylsiloxane compound is preferable, and a block copolymer of dimethylpolysiloxane and polyether is particularly preferably used.
The content of the foam stabilizer contained in the foam raw material depends on its kind, desired foam physical properties, etc., but when the polyol is 100 parts by mass, preferably 2.0 to 10 parts by mass, particularly preferably 3.0 to 8.0 parts by mass.

Examples of the cross-linking agent include high-molecular-weight cross-linking agents such as ethylene glycol, trimethylolpropane and the like, an ester oligomer chain-extended with ε-caprolactone, a trifunctional polyether polyol having a molecular weight of about 400 to 700, and ethylene. Examples include short-chain diol-based crosslinking agents such as glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,4-butanediol, glycerin, and trimethylolpropane. When a high molecular weight crosslinking agent is used, the foam can be made to have a lower hardness. In addition, when a short-chain diol-based cross-linking agent is used, the proportion of hard segments tends to increase. Therefore, it is preferable to set the blending amount in consideration of this point. Only one type of crosslinking agent may be used, or two or more types may be used in combination.
The content of the crosslinking agent contained in the foam raw material depends on the type and desired physical properties of the foam, but preferably 1.0 to 10 parts by mass, particularly preferably 2 when the polyol is 100 parts by mass. 0.0 to 5.0 parts by mass.

  An appropriate amount of additives generally used in the production of polyurethane foams such as ultraviolet absorbers, antioxidants, organic and inorganic fillers, and colorants can be blended with the foam raw material as necessary.

1-2. Method for Producing Polyurethane Foam Laminate The raw material for producing the polyurethane foam laminate of the present invention is a foam raw material having the above-described configuration, a gas-liquid mixture containing gas, and a resin film.
The gas mixed with the foam raw material is not particularly limited, and nitrogen gas, inert gas, dry air, or the like can be used. Of these, nitrogen gas is preferred.

In this invention, the said foam raw material and gas are stirred using the mixer 11, and it is set as the gas-liquid mixture 21a. Thereafter, the gas-liquid mixture 21a is supplied so as to be applied onto the resin film 22a, and then released onto the surface of the gas-liquid mixture 21a to be cast from above the release paper (or the resin that has been subjected to the release treatment). Film) 3 is supplied. And the thickness of the unhardened layer 21b which consists of the gas-liquid mixture 21a is adjusted by allowing the roll coater 12 etc. to pass through with this lamination | stacking state. It should be noted that whether or not the release paper 3 is used does not matter, but if this release paper 3 is used, the thickness of the uncured layer 21b can be easily adjusted, and the surface of the foam layer 21 obtained after the heat treatment (release paper 3). A skin layer can be formed on the side). By these steps, a three-layer type in which the uncured layer 21b has a resin film 22a (becomes the resin film layer 22) on one surface side (lower surface) and the release paper 3 is laminated on the other surface side (upper surface). A laminate is obtained.
Thereafter, the laminate is heated by a heat treatment apparatus. Thereby, the foam raw material can be made to react, the uncured layer 21b can be hardened, and the polyurethane foam laminated body 2 in which the foam layer 21 was formed can be obtained. In this polyurethane foam laminate 2, the foam layer 21 and the resin film layer 22 are firmly bonded. The obtained polyurethane foam laminate 2 may be wound into a paper tube or the like as a three-layer structure to form a roll, or as shown in FIG. 1, after the release paper 3 is peeled off, the two-layer laminate It is good also as a roll body. Further, it can be cut into a predetermined size on a production line to form a sheet. The sheets may then be stacked and packaged. In this case as well, the three layers may be stacked or may be stacked as a two-layer laminate.

Hereinafter, the manufacturing method of a polyurethane foam laminated body is demonstrated concretely.
As described above, the raw materials for producing the polyurethane foam laminate are the gas-liquid mixture 21a obtained using the foam raw material and gas, and the resin film 22a.
The method for preparing the foam raw material is not particularly limited, but preferably a polyisocyanate and a mixture containing no polyol, flame retardant, catalyst, etc. (hereinafter referred to as “first mixture”). It is a method of mixing. In addition, the additive mix | blended as needed is normally contained in a 1st mixture.

The preparation method of the gas-liquid mixture 21a is not particularly limited, and preferably 5 to 30% by volume and 70 to 95% by volume when the volume ratio of the foam raw material and the gas is 100% by volume in total. More preferably, the foam raw material and the gas are mixed so as to be 8 to 25% by volume and 75 to 92% by volume. With this mixing ratio, a gas-liquid mixture 21a suitable for forming a foam layer having the specific density can be prepared. The mixer 11 used for mixing the foam raw material and the gas is not particularly limited, but preferably an Oaks mixer, a Hobart mixer or the like is used. By these mixers 11, the foam raw material and the gas can be mixed uniformly, the foaming can be easily controlled, and the foamed gas-liquid mixture 21a can be generated as a more homogeneous one. .
The method of mixing the foam raw material and gas is preferably a method of blowing gas into the foam raw material previously stored in a mixing chamber or the like, and simultaneously supplying the foam raw material and gas into this chamber. Is the method. In these cases, the foam raw material may separately supply the polyisocyanate and the first mixture to the chamber.

The foam layer using the gas-liquid mixture is preferably formed by a mechanical floss method. According to this method, the volume of the gas-liquid mixture to be used and the volume of the resulting polyurethane foam can be made substantially the same. Therefore, the density of the polyurethane foam can be adjusted by the composition of the gas-liquid mixture, that is, the amount of gas introduced into the foam raw material.
In order to set the density of the foam to a predetermined value, the amount of gas used for forming the gas-liquid mixture can be determined as follows.
First, a weighted average of the density (true specific gravity) of each component contained in a foam material having a predetermined mass is obtained, and this is defined as the density (ρ) of the entire foam material. Then, the total volume of the foam raw material is calculated by dividing the mass of the foam raw material to be used by the density (ρ).
Next, the volume amount of the gas introduced into the foam material can be obtained from the total volume of the foam material and the target density of the foam (target density). This can be used for actual production to form a polyurethane foam layer having a desired density.

  The resin film 22a is not particularly limited as long as it does not cause deformation, alteration, or the like when the foam layer is formed. Moreover, what has the tensile strength as a support material for supporting a foam layer, tear strength, heat resistance, etc. is preferable. As the resin film 22a, a synthetic resin film is usually used. Examples of the synthetic resin include polyester resins such as polyethylene terephthalate and polybutylene terephthalate, polyurethane resins, polyolefin resins such as polyethylene and polypropylene, and polyamide resins. Of these, polyester resins, polyurethane resins, and polyamide resins are preferable from the viewpoints of strength, heat resistance, and the like. Moreover, when the polyurethane foam laminated body of this invention which has a resin film containing these resin is used as a gasket which seals two members, the outstanding adhesiveness and sealing performance can be obtained. In the present invention, the resin film 22a is more preferably a polyester resin, and particularly preferably polyethylene terephthalate.

  The thickness of the resin film 22a (the thickness of the resin film layer 22 constituting the polyurethane foam laminate) is not particularly limited. The preferred thickness is 25 μm or more, more preferably 25 to 125 μm, still more preferably 25 to 100 μm, and particularly preferably 30 to 70 μm. When the thickness is 25 μm or more, as shown in FIG. 1, when the continuous production proceeds, the polyurethane layer laminate can be stably produced by sufficiently withstanding the tensile stress in the molding direction of the foam layer 11. Is possible. Moreover, it is excellent in shape stability that the said resin film 22a is a polyethylene terephthalate and the thickness is 25-125 micrometers. Furthermore, when the polyurethane foam laminate of this configuration is used as a gasket, it is not excessively stiff, the work when interposing between housing members such as a mobile phone is easy, and excellent sealing properties, etc. can get.

The gas-liquid mixture 21a is supplied to the surface of the resin film 22a, and then the release paper 3 is supplied from the upper side to the surface of the gas-liquid mixture 21a to be cast to form a laminate. Next, this three-layer laminate is heated by the heat treatment apparatus 13 set to a predetermined temperature, and the foam raw material contained in the uncured layer 21b is reacted to form the foam layer 21.
The method for heating the three-layer laminate is not particularly limited, and is appropriately selected depending on the type of the heat treatment apparatus 13 and the like.

The heating temperature is appropriately selected according to the types of polyol and polyisocyanate in order to cure the foam raw material contained in the uncured layer 21b. This heating temperature is preferably 120 ° C to 200 ° C, preferably 140 ° C to 180 ° C, particularly preferably 150 ° C to 170 ° C.
The heating time is preferably 1 to 10 minutes, more preferably 1 to 5 minutes.

Examples of the heat treatment apparatus 13 include a heating furnace and a far infrared irradiation apparatus. In the case of using a heating furnace, heat treatment can be performed while using a heat source fixed in the apparatus while the three-layer laminate is stationary or moved. At this time, hot air may be supplied. In addition, when manufacturing a polyurethane foam laminated body continuously, it is preferable to heat a 3 layer type laminated body, moving in a heating furnace.
Heating of the three-layer laminate can be performed from either one or both sides of the resin film side and the release paper side. In the present invention, it is preferable to heat from both sides of the three-layer laminate in order to uniformly heat the whole and efficiently form a more uniform foam layer 21.

  When the manufacturing method of the polyurethane foam laminate of the present invention is the manufacturing system shown in FIG. 1, the preparation of the gas-liquid mixture 21a, the supply of the gas-liquid mixture 21a onto the resin film 22a, and the uncured layer 21b The polyurethane foam laminate can be continuously produced by continuously supplying the release paper or the like to the upper surface of the sheet, adjusting the thickness with a roll coater, and heating the three-layer laminate. In other words, the gas-liquid mixture 21a prepared by the mixer 11 is continuously fed out to the surface of the gas-liquid mixture 21a that is continuously supplied and cast on the moving resin film 22a at a predetermined supply speed. The release paper 3 is supplied at the same speed as the resin film 22 a, and the thickness is adjusted by the roll coater 12. Thereafter, the three-layer laminate is introduced into a heat treatment apparatus 13 disposed in the vicinity of the roll coater 12, for example, a heating furnace. When a heating furnace is used, usually, a three-layer laminate is introduced from one opening, moved in the heating furnace at the same or close to the resin film 22a, and led out from the other opening. Just do it. Thereby, the polyurethane foam laminated body which has the release paper 3 is manufactured. Thereafter, if necessary, the release paper 3 can be removed to form a polyurethane foam laminate comprising the foam layer 21 and the resin film layer 22.

  In addition, in the manufacturing method of the polyurethane foam laminated body of this invention, the foam layer 21 can be formed on both surfaces of the resin film layer 22. FIG. As the method, there are a method of forming the foam layer 21 one side at a time, and a method of forming the uncured layer 21b on both surfaces of the resin film 22a and then simultaneously heating to form the foam layer 21 at the same time.

  As described above, the polyurethane foam laminate of the present invention can be produced by a mechanical floss method in which water and a foaming agent are not blended with the foam raw material. Moreover, it can also manufacture by what is called a chemical floss method which mix | blends water and / or a foaming agent with foam raw material. In this case, as water, ion exchange water, tap water, distilled water, or the like can be used. Although the usage-amount of water is not specifically limited, When a polyol is 100 mass parts, it is 0.1-0.5 mass part normally, Most preferably, it is 0.2-0.4 mass part. Furthermore, a foaming agent is not specifically limited, A hydrocarbon, a substitute chlorofluorocarbon, etc. can be used. The amount of the foaming agent used is not particularly limited. Thus, in place of the mechanical froth method, the foaming state of the gas-liquid mixture is stably maintained even in the case of the chemical floss method using the foam raw material in which water and / or a foaming agent is blended, and the cell roughening, etc. Thus, a foam layer having a desired density and thickness can be easily formed. As a result, it can be set as the polyurethane foam laminated body provided with the foam layer provided with the outstanding physical property.

1-3. Physical Properties of Polyurethane Foam Laminate The polyurethane foam laminate of the present invention is a joined product of the foam layer 21 and the resin film layer 22 produced by the above method. The density of the foam layer is 100 to 280 kg / m ³ , preferably 120 to 260 kg / m ³ , particularly preferably 150 to 240 kg / m ³ .
The density of the foam layer can be calculated by dividing the mass obtained by subtracting the mass of the resin film layer from the mass of the laminate by the volume of the foam layer. The volume of the foam layer can be calculated as follows. That is, the laminate is cut into, for example, a rectangle to produce a test piece, and the vertical and horizontal dimensions of the test piece are measured with a caliper or the like. And after measuring the total thickness of a test piece with a dial thickness meter etc., the thickness of a foam layer is obtained by subtracting the thickness of a resin film layer. Then, the volume of the foam layer is calculated from the vertical and horizontal dimensions and the thickness of the foam layer.

Conventionally, when only a metal hydroxide powder is blended as a flame retardant and a low-density foam layer having a density of, for example, 280 kg / m ³ or less is formed, cell roughness or the like occurs, which is practical. A polyurethane foam laminate that could be provided could not be obtained. However, according to the production method of the present invention, by using a metal hydroxide and a liquid flame retardant together, a flexible foam layer having the above-mentioned specific density and suppressing defects such as cell roughness is obtained. And a polyurethane foam laminate having excellent flame retardancy.
Moreover, although the metal hydroxide powder and the liquid flame retardant are contained as a flame retardant in the polyurethane resin part forming the foam layer, these are held without bleeding out. The same applies to a case where a load such as compression is applied in an application described later. The content of the metal hydroxide powder and the liquid flame retardant is preferably 20 to 60 parts by mass and 5 to 20 parts by mass, more preferably 20 to 40 parts by mass and 5 to 10 parts, respectively, with respect to 100 parts by mass of the polyurethane. Part by mass.

The polyurethane foam laminate produced by the above-described method of the present invention can be provided with a foam layer having a small cell diameter as compared with a soft slab polyurethane foam produced by a known chemical foaming method. That is, the average cell diameter in the foam layer is preferably 50 to 350 μm, particularly preferably 50 to 250 μm. When the cell diameter of the foam layer is in the above range, a polyurethane foam laminate having excellent physical properties such as a small compressive residual strain can be obtained. When a polyurethane foam laminate with a small compressive residual strain is used as a gasket for sealing two members, both the resin film layer side surface and the foam layer side surface of the polyurethane foam laminate are sufficient for the two members. It can be adhered, and excellent sealing properties and the like can be obtained.
The average cell diameter can be calculated by observing the cross section of the foam layer with a scanning electron microscope at a magnification of 200 times, and dividing the total cell diameter by the number of cells.

The thickness of the foam layer is appropriately selected depending on the purpose, application, etc., but is usually 0.4 to 1.5 mm.
The thickness of the polyurethane foam laminate of the present invention is not particularly limited, but is usually 0.5 to 1.8 mm, particularly preferably 0.5 to 1.0 mm.
As described above, the polyurethane foam laminate of the present invention can be a laminate comprising foam layers on both sides of the resin film layer. In this case, the density, average cell diameter, and thickness in the two foam layers may be the same or different.

  Moreover, it is preferable that the skin layer is formed in the exposed surface (surface on the opposite side to the surface laminated | stacked on the resin film layer) of the foam layer in the polyurethane foam laminated body of this invention. When the polyurethane foam laminate having this skin layer is used as a gasket, the sealing at the peripheral edge portions of the two members constituting the casing of the device can be made complete. The skin layer can be confirmed by observing the cross section of the foam layer with an electron microscope or the like.

The 40% compression load of the polyurethane foam laminate of the present invention is preferably 0.002 to 0.02 MPa, particularly preferably 0.005 to 0.015 MPa. This 40% compression load is 40% CLD measured according to JIS K 6254.
Further, in the polyurethane foam laminate, the compression residual strain when compressed 50% at a temperature of 70 ° C. is preferably 10.0% or less, particularly preferably 6.0% or less. The lower limit is usually 0.3%. This compressive residual strain can be measured according to JIS K 6401.

2. Use of polyurethane foam laminate The polyurethane foam laminate of the present invention is a polyurethane foam laminate useful in applications such as gaskets.
The gasket of the present invention can be shaped according to the purpose, application and the like. For example, the gasket 100 shown in FIG. 2 is obtained by processing the polyurethane foam laminate of the present invention, and includes a resin film layer 102 and a foam layer 101 bonded to the surface of the resin film layer 102. An annular gasket is provided, and preferably has a skin layer on the surface (the upper surface in FIG. 2) of the foam layer 101. Thus, the gasket 100 in which the one surface side of the gasket 100 is constituted by the resin film layer 102 and the foam layer 101 having the skin layer is formed on the other surface side is used as the peripheral portion of the two members constituting the casing of the device. When used for sealing, the dust can be prevented from entering between the two members. That is, it is sufficiently prevented on both sides of the gasket 100 (the foam layer 101 side and the resin film layer 102 side).
The shape of the gasket of the present invention is not limited to the one having an opening larger than the main body portion as shown in FIG. 2. For example, the gasket has a small area with respect to a sheet (polyurethane foam laminate) having a predetermined shape. The opening may be provided.

  Although the thickness of the said gasket is not specifically limited, Usually, it is 0.4-1.5 mm, Most preferably, it is 1.0-1.5 mm. When the gasket thickness is 0.4 to 1.5 mm, excellent sealing properties can be obtained while taking advantage of the flexibility of the polyurethane foam laminate.

  The method for obtaining the gasket 100 having an annular structure as shown in FIG. 2 is not particularly limited, and examples thereof include a method of punching using a punching die and a method of continuously cutting with a cutting machine. Of these, the punching method is preferable. Further, as described above, since the foam layer 101 has a low density and excellent flexibility, the foam layer 101 is not damaged or missing at the peripheral edge or the like in the processed portion during punching or the like.

  The gasket of the present invention can be used by interposing it between casing members of electronic equipment. The electronic device is not particularly limited, and examples thereof include portable electronic devices such as a mobile phone, a digital camera, a digital video camera, a portable computer, a portable music device, a portable game machine, and a navigation device. Among these electronic devices, it is preferable to use the gasket of the present invention for a mobile phone that is owned by many people and is often carried around when going out and is easily in contact with fibers such as clothes.

  The housing of an electronic device is usually composed of a plurality of housing members facing each other, and a gasket is interposed between the housing members. However, in recent years, with downsizing and higher performance of electronic devices. There is a need for a gasket that is easy to interpose, does not require a groove for fitting the gasket into the housing member, and has excellent sealing properties. Further, since the casing member is thinned and the members are warped when the members are fastened as in the conventional case, a gasket having sufficient flexibility is required. Under such circumstances, the gasket of the present invention has a low density and is sufficiently flexible, and is advantageous in that it can cope with downsizing of electronic devices, in particular, reduction in thickness.

  Hereinafter, the present invention will be described specifically by way of examples. In the following, “part” is based on mass unless otherwise specified.

The raw materials used for the production of the polyurethane foam laminate are as follows.
(1) Polyether polyol A
“GP-3000” (trade name) manufactured by Sanyo Chemical Industries, Ltd. was used.
(2) Polyether polyol B
“GP-600” (trade name) manufactured by Sanyo Kasei Co., Ltd. was used.
(3) Catalyst Stanas octoate manufactured by Johoku Chemical Co., Ltd. was used.
(4) Foam stabilizer A silicone foam stabilizer “L-5617” (trade name) manufactured by Momentive was used. This product is a block copolymer of dimethylpolysiloxane and polyether.
(5) Metal hydroxide powder Aluminum hydroxide powder “Hijilite H-10” (trade name) manufactured by Showa Denko KK was used.
(6) Phosphorus flame retardant Aliphatic condensed phosphate ester “DAIGUARD880” (trade name) manufactured by Daihachi Chemical Industry Co., Ltd. was used. This product is a pale yellow transparent liquid at 25 ° C.
(7) Polyisocyanate Crude MDI “C-1130” (trade name) manufactured by Nippon Polyurethane was used. The isocyanate group content is 31%.
(8) Resin film A polyethylene terephthalate film having a thickness of 50 μm was used.

Examples 1-4 and 6-15 and Comparative Examples 1-7
100 parts of polyether polyol (polyether polyols A and B were used at a mass ratio of 90/10), 0.1 part of catalyst, 5 parts of foam stabilizer, and the amounts shown in Tables 1 to 4 The metal hydroxide powder and the phosphorus flame retardant were mixed and stirred to prepare a first mixture.

  Then, this 1st mixture and the polyisocyanate of the compounding quantity from which an isocyanate index becomes 0.9-1.1 were thrown into the chamber arrange | positioned at the Oaks mixer. And simultaneously, the nitrogen gas of the quantity used as the predetermined volume ratio described in Table 1-Table 4 was inject | poured so that it might become the target density of the foam layer described in Table 1-Table 4.

Next, the above components were stirred and mixed in a chamber to prepare a foamed gas-liquid mixture. And this gas-liquid mixture is supplied on the resin film currently sent out at a speed of 5 m / min, and the release paper is supplied to the surface of the gas-liquid mixture to be cast from the upper side at the same speed as the resin film. And it adjusted to predetermined thickness with the roll coater, and formed the non-hardened layer which consists of a gas-liquid mixture (refer FIG. 1).
Thereafter, a three-layer laminate comprising a resin film, an uncured layer and a release paper was introduced into a heating furnace adjusted to 160 ° C. by a far infrared heater and heated (the length of the heating furnace was 5 m). The heating time is 1 minute.) Next, the release paper was peeled from the laminate, and the polyurethane foam laminate formed by joining the resin film and the foam layer was wound around a paper tube. The thickness of the polyurethane foam laminate was measured with a dial thickness meter (Tables 1 to 4).

Example 5
A polyurethane foam laminate was obtained in the same manner as above except that only 100 parts of polyether polyol A was used as the polyether polyol (Table 1).

A test piece was cut out from the polyurethane foam laminate produced as described above, and the density, average cell diameter, 40% compression load and compressive residual strain of the foam layer were measured, and the appearance of the foam layer, the presence or absence of bleed, Existence and flame retardancy were evaluated. The results are shown in Tables 1 to 4.
(1) Density of foam layer The obtained polyurethane foam laminate was cut into a square shape (50 mm x 50 mm) to prepare a test piece, and the vertical and horizontal dimensions of the test piece were accurately measured with a caliper. And the thickness of the foam layer was obtained by subtracting the thickness of the resin film from the thickness of the laminated body shown in each table. Thereafter, the volume of the foam layer is calculated using the vertical and horizontal dimensions and the thickness of the foam layer. Next, the mass obtained by subtracting the mass of the resin film layer from the mass of the test piece was divided by the volume of the foam to obtain the density of the foam layer.
(2) Average cell diameter The cross section of the foam layer in the obtained polyurethane foam laminate was observed with a scanning electron microscope at a magnification of 200 times, and the size of 50 foamed cells in the image was measured. Then, the total of these cell diameters was divided by the number of cells to obtain an average cell diameter.
(3) Load at 40% compression Measured according to JIS K 6254. Specifically, the polyurethane foam laminate was punched to obtain a circular test piece having a diameter of 50 mm. Then, a compression jig having the same diameter as that of the test piece is brought into contact with the test piece concentrically, and is compressed by 40% at a speed of 1 mm / min at a temperature of 23 ° C. using a compression tester (60 before compression). %), And the load at that time was measured. From the obtained load, a 40% compression load (unit: MPa) was calculated by the following formula.
40% compression load = [40% compression load (N) / area of specimen (mm ² )]
(4) Compressive residual strain Measured according to JIS K 6401. Specifically, the polyurethane foam laminate was punched to obtain a 50 mm × 50 mm test piece. Then, this test piece was compressed 50% at a temperature of 70 ° C. using a compression tester and left for 22 hours. Thereafter, the compression was released and the sample was allowed to stand at 23 ° C. for 30 minutes, and then the thickness of the test piece was measured. Using the thickness before and after the compression test, the compression residual strain was calculated by the following formula.
Compression residual strain (%) = [(Thickness before compression−Thickness after opening) / Thickness before compression] × 100
(5) Appearance of foam layer The surface of the foam layer of the polyurethane foam laminate is observed with an optical microscope, and the number of large-diameter cells having a diameter (maximum dimension) of 700 μm or more existing in a 10 cm square is counted. Evaluated. “Good” in the table means that there are less than 20 large-diameter cells, and “cell roughness” means that 20 or more large-diameter cells were observed.
(6) Presence / absence of bleed Cutting was performed on the polyurethane foam laminate to obtain a 50 mm × 50 mm test piece. Then, after placing a copper foil (60 mm × 60 mm × 0.1 mm) on the surface of the foam layer of this test piece, it was compressed by 50% at a temperature of 70 ° C. using a compression tester and kept for 168 hours. I left it alone. Next, the compression was released, and the surface of the peeled copper foil (contact surface with the foam layer) was visually observed to evaluate the bleeding property of the phosphorus-based flame retardant. “None” in the table means that no foreign matter is observed on the copper foil surface and bleed out, and “Yes” means that foreign matter is observed on the copper foil surface and bleed out.
(7) Presence / absence of scratch The polyurethane foam laminate was cut to obtain a circular test piece having a diameter of 50 mm. And it mounted in the center part of the upper surface of the disk-shaped mounting base of a testing apparatus with the foam layer of this test piece facing upwards. Thereafter, a pressing body made of stainless steel having a diameter of 50 mm was brought into contact with the test piece so as to be concentric with the test piece, and a load of 1.2 kg was applied to the pressing body. Next, the mounting table is rotated at a speed of 43 rotations / minute together with the test piece (the speed at which the mark attached to an arbitrary position on the outer edge of the test piece moves with the rotation is 50 mm / min). The rotation was stopped when 10 rotations were made. And the foam layer of the test piece was observed visually and scratch property was evaluated. “◯” in the table indicates that no scratches were observed on the surface of the foam layer, “Δ” indicates that scratches with a maximum dimension of less than 5 mm were observed, and “X” indicates scratches with a maximum dimension of 5 mm or more. It means that it was observed.
(8) Flame retardancy Flame retardancy was evaluated by whether or not it passed the HBF standard, which is a flame retardance standard defined in UL94. “◯” in the table means that the HBF standard was passed, and “x” means that the HBF standard was not passed.

  As is apparent from Tables 1 to 3, with respect to the polyol content, the foam raw material containing a predetermined amount of metal hydroxide powder and a phosphorus-based flame retardant is used in a predetermined density range. It can be seen that in the polyurethane foam laminates of Examples 1 to 15 having the foam layer, the 40% compression load is sufficiently small and the compression residual strain is also small. Further, in all the examples, the appearance of the foam layer is good, and it is excellent without bleeding out of the phosphorus-based flame retardant. In addition, in the presence or absence of scratches, a small number of scratches are observed in some examples where the density of the foam layer is lower, but this is not a major problem, and it is a polyurethane foam laminate that can be used satisfactorily in applications such as gaskets. I understand that there is. Furthermore, it turns out that it has passed the HBF standard in all the Examples and has the outstanding flame retardance.

  On the other hand, as can be seen from Table 4, even when the density of the foam layer was within the preferred range, cell roughness and scratches occurred in Comparative Example 1 containing no phosphorus flame retardant. Moreover, in the comparative example 2 in which the metal hydroxide powder is not contained, the flame retardancy was unacceptable. In Comparative Examples 2 and 3 in which the metal hydroxide powder was not contained, the compressive residual strain was remarkably increased. Furthermore, although containing a predetermined amount of metal hydroxide powder and phosphorus flame retardant, in Comparative Examples 4 and 7 where the density of the foam layer was too low, cell roughness and scratches occurred. In Comparative Example 5 and Comparative Example 6, there is no particular problem in terms of physical properties, but since the density of the foam layer is too high, it is a polyurethane foam laminate that cannot be put to practical use particularly in gasket applications.

  Note that the present invention is not limited to the above-described specific examples, and can be variously modified examples within the scope of the present invention according to the purpose and application. For example, the same polyurethane foam laminate can be produced by so-called chemical flossing method by blending the foam raw material with about 0.2 to 0.4 part of water (with 100 parts of polyol).

  The present invention can be used in various product fields where it is necessary to prevent water and dust from entering. In recent years, the thickness, size, and performance have been remarkably increased, and the utility value is higher in the fields of various electronic devices that also require excellent design. Many mobile phones, digital cameras, navigation devices, etc. It is particularly useful for electronic devices owned by many people and often carried around, especially mobile phones that are always carried around.

Claims (11)

A foam raw material containing a polyisocyanate, a polyol and a flame retardant is mixed with a gas to form a gas-liquid mixture. Then, the gas-liquid mixture is supplied onto a resin film, and then the gas-liquid mixture is heated. In the polyurethane foam laminate having a resin film layer made of the resin film and a foam layer made of the produced polyurethane foam, obtained by reacting the foam raw material,
The flame retardant contained in the foam raw material includes a metal hydroxide powder and a liquid flame retardant, and when the polyol is 100 parts by mass, the metal hydroxide powder is 20 to 60 parts by mass. The liquid flame retardant is 5 to 20 parts by mass, and
A polyurethane foam laminate, wherein the foam layer has a density of 100 to 280 kg / m ³ .   The polyurethane foam laminate according to claim 1, wherein the liquid flame retardant is a phosphorus flame retardant.   The polyurethane foam laminate according to claim 1 or 2, wherein the metal hydroxide powder has an average particle size of 10 to 100 µm.   The polyurethane foam laminate according to any one of claims 1 to 3, wherein the resin film layer contains polyethylene terephthalate, and the thickness of the resin film layer is 25 to 125 µm.   The polyurethane foam laminate according to any one of claims 1 to 4, wherein the foam layer has an average cell diameter of 50 to 300 µm.   The polyurethane foam laminate according to any one of claims 1 to 5, wherein the foam layer has a skin layer on a surface opposite to a surface laminated on the resin film layer.   The polyurethane foam laminate according to any one of claims 1 to 6, wherein a load when compressed by 40% is 0.002 to 0.02 MPa.   The polyurethane foam laminate according to any one of claims 1 to 7, which has a compression residual strain of not more than 10.0% when compressed by 50% at a temperature of 70 ° C. A foam raw material containing a polyisocyanate, a polyol and a flame retardant is mixed with a gas to form a gas-liquid mixture. Then, the gas-liquid mixture is supplied onto a resin film, and then the gas-liquid mixture is heated. And reacting the foam raw material to produce a polyurethane foam laminate having a resin film layer comprising the resin film and a foam layer comprising a polyurethane foam produced by reaction curing of the foam raw material.
The flame retardant contained in the foam raw material includes a metal hydroxide powder and a liquid flame retardant, and when the polyol is 100 parts by mass, the metal hydroxide powder is 20 to 60 parts by mass. The liquid flame retardant is 5 to 20 parts by mass, and
The method for producing a polyurethane foam laminate, wherein the foam layer has a density of 100 to 280 kg / m ³ .   A gasket comprising the polyurethane foam laminate according to any one of claims 1 to 8.   The gasket according to claim 10, which has a thickness of 0.4 to 1.5 mm.

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