JP5505921B2 - Flexible polyurethane foam - Google Patents

Description

  The present invention relates to a flexible polyurethane foam, and in particular, to a flexible polyurethane foam having low hardness, low strain and good air permeability.

  Soft polyurethane foams are widely used as cushion materials such as pillows, mattresses and seat cushions. In addition, soft polyurethane foams have uses such as pillows that require low hardness, low distortion, and air permeability. However, it has been difficult for conventional soft polyurethane foams to be good in all of low hardness, low strain, and air permeability.

  Soft polyurethane foams include open foam products and molded foam products. An open foamed product is obtained by naturally foaming and curing a polyurethane raw material at room temperature and atmospheric pressure, and then forming a product shape by cutting or the like. A typical open foam product is a slab foam product. Slab foamed products are produced continuously by discharging polyurethane raw material onto a belt conveyor, and the raw material naturally foams and cures at room temperature and atmospheric pressure while the belt conveyor moves. After being cured (cured) in a drying furnace, it is cut into a predetermined shape. On the other hand, a molded foam product is obtained by injecting a polyurethane raw material into a mold (molding die), causing foaming in the mold, and then demolding. The slab foamed product has the advantage that it is not necessary to prepare a mold for each product and can be used for various products. On the other hand, the molded foamed product is shaped into the product shape in the mold, so that it can be demolded. There is an advantage that post-processing for making a product shape later becomes unnecessary.

  Conventionally, although the molded foam product has a low hardness, it is difficult to obtain a highly breathable product and also a product with little distortion. In particular, the molded foam product has a cell structure in which the ratio of closed cells with closed cell membranes is high. Therefore, if crushing that compresses the molded product after foaming is not performed and the cell membrane is not destroyed, bubbles will be generated by subsequent cooling. Since the shrinkage causes deformation of the foam, extra man-hours are required for crushing.

  Moreover, due to the problem of exhaustion of petroleum raw materials, in recent years, dependence on plant-derived raw materials has increased, and in the field of flexible polyurethane foams, use of castor oil and polyols extracted or purified from soybeans is expected.

  In Patent Document 1, in a flexible polyurethane mold foam used for an automobile seat pad or the like, the content of a chain terminal ethylene oxide unit as a polyol is 4 to 12 weights in order to achieve both low resilience and vibration absorption. % And a hydroxyl value of 25 to 60 mg KOH / g is used, and 1 to 3 parts by weight of water as a blowing agent is blended with 100 parts by weight of polyol. Further, in Patent Document 2, for the purpose of improving the curing property of the foam surface and the compression set of the foam, it is hydrogenated and modified with amine, and then molded using a hydroxyl-terminated polyol. Polyurethane foam is disclosed.

  However, in the polyurethane foams described in Patent Document 1 and Patent Document 2, it is difficult to improve all of low hardness, low strain, and air permeability, and it is particularly difficult to achieve high air permeability.

JP 2004-83605 A JP-A-5-140052

  The present invention has been made in view of the above points, and an object of the present invention is to provide a flexible polyurethane foam having all of low hardness, low distortion, and air permeability.

The invention according to claim 1 is a polyurethane foam formed from a polyurethane raw material containing a polyol, a polyisocyanate, a foaming agent and a catalyst. The polyol comprises an ester condensate of a fatty acid and a polyfunctional alcohol and has 2 functional groups. a polyol (a) derived from a 4 polyols vegetable oil, a polyoxyalkylene chain polyether polyol is a by the polyoxyalkylene chain polyol containing oxyethylene groups 45-85 wt% with (B) and The amount of the polyol (A) is 10 to 50 parts by weight in 100 parts by weight of the polyol, and the amount of the polyol (B) is the amount of the polyol (A) from 100 parts by weight of the polyol. The remaining amount after subtracting 90 to 50 parts by weight, Characterized by using the Kutomo toluene diisocyanate.

The invention according to claim 2 is the polyurethane foam according to claim 1, wherein the polyisocyanate is a combination of toluene diisocyanate (TDI) and diphenylmethane diisocyanate (MDI), and the weight ratio of TDI / MDI is 80/20. The hardness is 6 to 49 N (based on JIS K6400-2: 2004 D method).

According to the present invention, the flexible polyurethane foam is a polyol having 2 to 4 functional groups, which is an ester condensate of a fatty acid and a polyfunctional alcohol, and has a polyol (A) derived from vegetable oil and a polyoxyalkylene chain. A polyol (B) which is a polyether polyol and contains 45 to 85% by weight of oxyethylene groups in the polyoxyalkylene chain, and the amount of the polyol (A) is 10 to 10 parts by weight in 100 parts by weight of the polyol. The amount of the polyol (B) is 90 to 50 parts by weight, which is the remaining amount obtained by subtracting the amount of the polyol (A) from 100 parts by weight of the polyol, and the polyisocyanate contains at least toluene. By using diisocyanate, a product having low hardness, low strain and good air permeability can be obtained. The present invention is applicable to both open foam products (slab foam products) and molded foam products.

  The flexible polyurethane foam in the present invention is formed by open foaming (slab foaming) or mold foaming from a polyurethane raw material containing polyol, polyisocyanate, foaming agent and catalyst.

In the present invention, two types of polyol (A) and polyol (B) are used in combination. The polyol (A) is composed of an ester condensate of a fatty acid and a polyfunctional alcohol . Examples of the fatty acid include ricinoleic acid, linoleic acid, linolenic acid, and oleic acid. Polyfunctional alcohols include bifunctional ethylene glycol, diethylene glycol, propylene glycol, etc., trifunctional glycerin, trimethylolpropane, etc., tetrafunctional pentaerythritol, hexafunctional sorbitol, octafunctional. Examples include sucrose. Examples of the polyol comprising an ester condensate of a fatty acid and a polyfunctional alcohol include polyols derived from vegetable oils based on castor oil, soybean oil, rapeseed oil, cottonseed oil and the like. In particular, as the polyol (A), a castor oil polyol in which the fatty acid is ricinoleic acid is preferable from the viewpoint of availability. Furthermore, in order to make the flexible polyurethane foam low in hardness and less distorted, the polyol (A) having 2 to 4 functional groups is used. Further, the polyol (A) preferably has a hydroxyl value (OHV) of 40 to 350 mgKOH / g and a molecular weight of 500 to 4000.

The amount of the polyol (A) is preferably 10 to 50 parts by weight in 100 parts by weight of the total polyol. When the amount of the polyol (A) is less than 10 parts by weight, the amount of the highly reactive polyol (B) having a high content of oxyethylene groups is increased, so that the reactivity of the polyurethane raw material is increased and the foaming agent is increased. Further, the process range such as the addition amount of the catalyst and the like becomes narrow, it is difficult to obtain aeration, and it becomes difficult to obtain a good foam. In particular, with a molded foam, it is difficult to obtain a good polyurethane foam. On the other hand, when the amount of the polyol (A) exceeds 50 parts by weight, the reactivity of the polyurethane raw material becomes low and it becomes difficult to foam normally, and it becomes difficult to obtain a good foam. A more preferable amount of the polyol (A) is 30 to 50 parts by weight out of 100 parts by weight of the total polyols, and by setting this range, high air permeability is obtained, which is more preferable.

The said polyol (B) consists of a polyether polyol which has a polyoxyalkylene chain, and what contains 45 to 85 weight % of oxyethylene groups in the said polyoxyalkylene chain is used. The polyether polyol having an oxyethylene group content of 45 to 85% by weight is a polyol having an excess oxyethylene group content that is not used in a normal molded foam product. The amount of oxyethylene groups in the present invention is the ratio of oxyethylene groups in the polyoxyalkylene chain, in the present invention are 45 to 85% by weight of polyoxy alkylene chain weight (polyoxy alkylene total molecular weight). Polyether polyols having a polyoxyalkylene chain include polyvalent polyols such as ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, dipropylene glycol, trimethylene glycol, glycerin, pentaerythritol, trimethylolpropane, sorbitol, and sucrose. Products obtained by adding ethylene oxide using alcohol as an initiator, products obtained by adding ethylene oxide to polyhydric phenols such as bisphenol A, polyamines such as ethylenediamine, diethylenetriamine and triethylenetetramine, and alkanolamines such as triethanolamine and diethanolamine The thing etc. which added ethylene oxide to can be mentioned. When the oxyethylene group is less than 45% by weight, foaming is possible, but it is difficult to obtain a highly breathable foam. On the other hand, when it exceeds 85% by weight , the reactivity becomes significant. It will be difficult to ensure.

  The amount of the polyol (B) is the remaining amount obtained by subtracting the amount of the polyol (A) from 100 parts by weight of the polyol, and is 90 to 50 parts by weight. When the amount of the polyol (B) exceeds 90 Jiro, the reactivity of the polyol raw material becomes high and a product with good air permeability cannot be obtained. In particular, in the case of a molded foam, a process range cannot be obtained, shrinkage (shrinkage) occurs in the foam, or a significant gas accumulates in the foam, and a good foam cannot be obtained. On the other hand, when the amount of the polyol (B) is less than 50 parts by weight, it becomes difficult to balance with the polyol (A) to be used together, and a foam having a balance of low hardness, low distortion and air permeability can be obtained. become unable. Further, the polyol (B) preferably has a hydroxyl value (OHV) of 30 to 100 mgKOH / g and a molecular weight of 1000 to 6500.

  The polyisocyanate in the present invention contains at least toluene diisocyanate (TDI). By including toluene diisocyanate, the flexible polyurethane foam can have a lower density and a lower hardness. The toluene diisocyanate used includes 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, and a mixture of 2,4-toluene diisocyanate and 2,6-toluene diisocyanate, and any of them can be used.

  The polyisocyanate may be used in combination with other diisocyanates together with toluene diisocyanate. The polyisocyanate used in combination may be aromatic, alicyclic or aliphatic, and may be a bifunctional isocyanate having two isocyanate groups in one molecule, or in one molecule. It may be a trifunctional or higher functional isocyanate having three or more isocyanate groups, and these may be used alone or in combination.

  For example, as the bifunctional isocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4′-diphenylmethane diisocyanate (MDI), 2,4′-diphenylmethane diate (MDI), 2,2′-diphenylmethane Aromatic compounds such as diisocyanate (MDI), xylylene diisocyanate, 3,3′-dimethyl-4,4′-biphenylene diisonate, 3,3′-dimethoxy-4,4′-biphenylene diisocyanate, cyclohexane Alicyclic ones such as 1,4-diisocyanate, isophorone diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, methylcyclohexane diisocyanate, butane-1,4-diisocyanate, hexamethylene diisocyanate Isopropylene diisocyanate, methylene diisocyanate, there may be mentioned aliphatic, such as lysine isocyanate.

Examples of the tri- or higher functional isocyanate include 1-methylbenzole-2,4,6-triisocyanate, 1,3,5-trimethylbenzole-2,4,6-triisocyanate, biphenyl-2,4,4 ′. -Triisocyanate, diphenylmethane-2,4,4'-triisocyanate, methyldiphenylmethane-4,6,4'-triisocyanate, 4,4'-dimethyldiphenylmethane-2,2 ', 5,5' tetraisocyanate, triisocyanate Examples thereof include phenylmethane-4,4 ′, 4 ″ -triisocyanate, polymeric MDI, and the like. Other urethane prepolymers can also be used. The polyisocyanate is not limited to one type, but one type. For example, one type of aliphatic isocyanate and aromatic Two types of socyanate may be used in combination, and in particular, the combination of toluene diisocyanate (TDI) and diphenylmethane diisocyanate (MDI) is preferable, and those having a weight ratio of TDI / MDI of about 80/20 Particularly preferred for obtaining low density, low hardness, and high air permeability, blends of TDI and MDI are preferred polyisocyanates because they are widely used in polyurethane foam industrial applications and are inexpensive. Furthermore, the blend (combination use) of TDI and MDI increases the viscosity of the polyisocyanate in the case of molding, reduces the difference in viscosity from the polyol, makes the mixing and mixing of the foaming raw material uniform, and improves the foaming effect. There is also.

  The isocyanate index [NCO (mol) / OH (mol) x 100 in the polyurethane raw material] is preferably 70 to 100 in order to obtain low hardness and high air permeability. When the isocyanate index is less than 70, a sufficient reaction for forming the foam is not performed, and the distortion becomes large, and a good foam tends not to be obtained. On the other hand, if it exceeds 100, it will be difficult to ensure the process range, and even if a foam is obtained, the hardness will be too high, making it unsuitable for relatively low hardness applications such as bedding. A more preferred isocyanate index is 75-90.

  The foaming agent in this invention can use a well-known thing for polyurethane foams. For example, water, pentane, cyclopentane, hexane, cyclohexane, dichloromethane, carbon dioxide gas or the like is used. The blending amount of the foaming agent is an appropriate amount, but in the case of water, it is usually about 1 to 4 parts by weight with respect to 100 parts by weight of the polyol component.

  The catalyst in this invention can use a well-known thing for polyurethane foams, It does not specifically limit. Examples of usable catalysts include amine catalysts such as triethylamine, triethylenediamine, and tetramethylguanidine, tin catalysts such as dibutyltin dilaurate and stannous octoate, and metal catalysts such as phenylmercurypropionate and lead octenoate ( Also referred to as an organometallic catalyst.). The compounding amount of the catalyst is appropriately determined depending on the type of the catalyst, but is generally about 0.3 to 4.0 parts by weight with respect to 100 parts by weight of the polyol component.

  In addition, a foam stabilizer is blended in the polyurethane raw material. As the foam stabilizer, those known for polyurethane foams can be used, and examples thereof include silicone foam stabilizers, fluorine-containing compound foam stabilizers and surfactants. In particular, silicone foam stabilizers are suitable. Silicone foam stabilizers include those composed mainly of siloxane chains, siloxane chains and polyether chains having a linear structure, branched and branched, and polyether chains modified in a pendant form to siloxane chains. Etc.

  The polyurethane raw material is appropriately mixed with an auxiliary agent. Examples of the auxiliary agent include a colorant, a flame retardant, and a plasticizer. The plasticizer also has an effect of reducing the hardness of the flexible polyurethane foam. For example, when the plasticizer is blended in an amount of 5 to 30 parts by weight with respect to 100 parts by weight of the polyol, a foam having a lower hardness can be obtained. As the plasticizer, those known for polyurethane foams can be used. For example, phosphate ester, dibutyl phthalate, dioctyl phthalate, dibutyl benzyl phthalate, diisodecyl phthalate, di-2-ethylhexyl adipate, 2-ethylhexyl sebacate, tri-2-ethylhexyl trimellitic acid, butyl oleate And a mixture of two or more thereof. In addition, the phosphate ester compound can be expected to have an effect as a flame retardant in addition to the plastic effect.

  Examples and comparative examples are specifically shown below, but the present invention is not limited to these examples. Polyurethane raw materials were prepared based on the formulations shown in Tables 1 to 3, and polyurethane foams of Examples and Comparative Examples were produced by mold foaming and open foaming. Examples 1 to 11 and Comparative Examples 1 to 4 are molded foam products, and Examples 12 to 14 and Comparative Examples 5 to 6 are open foam products. Mold foaming in Examples and Comparative Examples is performed by injecting the polyurethane raw material (mixed liquid) of each example into a cavity (molding recess) of a mold (mold), and clamping the mold to react and foam the raw material components in the mold. By the method. In general, in mold foaming, the heating temperature of the mold is preferably 50 to 70 ° C., and the heating time (time from injection to demolding) is preferably 5 to 10 minutes. When the heating temperature is less than 50 ° C. or the heating time is less than 5 minutes, reactions such as urethanization reaction, foaming reaction, and cross-linking reaction are delayed and a good flexible polyurethane foam cannot be obtained. On the other hand, when the heating temperature exceeds 70 ° C. or when the heating time exceeds 10 minutes, the reaction proceeds excessively, the crosslinking density of the foam becomes too high, and the resulting foam lacks flexibility. It becomes a trend. In the present example and comparative example, the mold was set to 50 ° C. and left for 4 minutes after injection to leave for 4 minutes to foam in the mold, and then removed to obtain polyurethane foams of the example and comparative example. . In each of the examples, a predetermined product could be obtained without crushing. However, in Comparative Examples 3 and 4, crushing was required to obtain the predetermined product. On the other hand, in the open foaming in the examples and comparative examples, the mold foam and the corresponding raw materials are discharged into a box with the upper part opened at room temperature (25 ° C.) and atmospheric pressure, spontaneously foamed and cured, and the examples and comparisons. An example polyurethane foam was obtained.

In Table 1, polyol A1 is a castor oil polyol having 2 functional groups and a hydroxyl value (OHV) of 90 mgKOH / g, product number: H-56, manufactured by Ito Oil Co., Ltd., polyol A2 has 3 functional groups and a hydroxyl value (OHV) of 100 mgKOH / g. Castor oil polyol, product number: H-57, manufactured by Ito Oil Co., Ltd., polyol A3 has 2 functional groups, hydroxyl value (OHV) 52 mg KOH / g, 2 functional group soybean oil polyol, product number: R2-052, manufactured by USSC, Polyol B1 has an average molecular weight of 2,800, functional group number 3, hydroxyl value (OHV) 60 mgKOH / g, EO = 80 wt %, product number: FA103, manufactured by Sanyo Chemical Industries, polyol B2 has an average molecular weight of 2500, functional group number 3, hydroxyl value (OHV) 68.5mgKOH / g, EO = 50 wt%, product number: GR2505, Asahi Chemical Industry Co., polyol C has an average molecular weight 5000, functionality 3, a hydroxyl value (OHV) 36mgKOH / g, EO = 20 wt%, product number: No. 38, manufactured by Sanyo Chemical Industries, Ltd., amine catalyst 1 is diethanolamine, amine catalyst 2 is triethylenediamine 33% and dipropylene glycol 67%, product number: DABCO33LV, manufactured by Sankyo Air Products Co., Ltd., foam stabilizer 1 is silicone-based , Product number: SH-192, manufactured by Toray Dow Corning Co., Ltd., foam stabilizer 2 is silicone, product number: SF2961, manufactured by Toray Dow Corning Co., Ltd., plasticizer is product number: TMCPP, Daihachi Chemical Industry Co., Ltd. Manufactured, polyisocyanate 1 is a mixture of TDI / MDI = 80/20, NCO% = 44.6%, product number: Coronate 1021, manufactured by Nippon Polyurethane Industry Co., Ltd., polyisocyanate 2 is TDI / MDI = 50/50 Mixture, NCO% = 39.3%, Product No .: TM5050, BFS FINOR Is made of polyurethane-click Corporation.

Examples 1 to 5 are 30 parts by weight of castor oil polyol A2 having 3 functional groups and OHV = 100 mgKOH / g as polyol (A) in the present invention, and 70% by weight of polyol B1 having EO = 80% by weight as polyol (B). Examples 1 to 4 are examples in which the isocyanate index is changed in the range of 75 to 95, and Example 5 is an example in which a polyisocyanate different from Examples 1 to 4 is used. is there. Example 6 is an example in which 10 parts by weight of polyol A2 and 90 parts by weight of polyol B1 are used. Example 7 is 30 parts by weight of castor oil polyol A1 having 2 functional groups and OHV = 90 mgKOH / g as polyol (A). B) Example using 70 parts by weight of polyol B1 of EO = 80 wt %, Example 8 is an example in which polyol A2 used in Examples 1 to 6 is 50 parts by weight, and polyol B1 is 50 parts by weight, Example 9 is an example in which soybean oil polyol A3 having 2 functional groups and OHV = 52 mgKOH / g was used instead of polyol A2 in Example 1, and Example 10 was replaced with polyol B1 in Example 1 and EO = 50% by weight . In Example 11 using Polyol B2, the polyol A2 in Example 10 was reduced from 30 parts by weight to 20 parts by weight, and the polyol of Example 10 was used. The Lumpur B2 is an example in which increased to 80 parts by weight 70 parts by weight. Examples 12 to 14 are examples formed by open foaming instead of mold foaming of Examples 1 to 11. Example 12 has the same formulation as Example 1, Example 13 has the same formulation as Example 7, and Example 14 is a soybean oil polyol A3 having 2 functional groups and OHV = 52 mgKOH / g as polyol (A). Is 30 parts by weight, and the polyol (B) is 70 parts by weight of EO = 50% by weight of polyol B2.

On the other hand, Comparative Example 1 is the number of functional groups 3, OHV = 100mgKOH / g example castor oil polyol A2 was molded foam using 100 parts by weight of Comparative Example 2, molded foam using 100 parts by weight of EO = 80% by weight of the polyol B1 Comparative Example 3 is an example in which 100 parts by weight of polyol C of EO = 20% by weight is molded and foamed. Comparative Example 4 is castor oil polyol A2 having a functional group number of 3 and OHV = 100 mgKOH / g, 30 parts by weight and EO. = 20% by weight polyol C, 70% by weight mold foaming, Comparative Example 5 is EO = 80% by weight polyol B1 100% by weight open foaming, Comparative Example 6 is EO = 20% by weight In this example, 100 parts by weight of polyol C is used for open foaming.

The foaming state of the examples and comparative examples was judged visually. The results of the foamed state are shown at the bottom of Tables 1 to 3. The foaming state is ○ when the foam is normally foamed, the reactivity is too low, the foam goes down in the middle of foaming, and when the foam is not foamed normally or the reactivity is too high, excessive gas is generated and shrinks. The case where it occurred was indicated by x. About Examples 1-14, all foamed well. On the other hand, in Comparative Example 1, by using 100 parts by weight of castor oil polyol A2 having 3 functional groups and OHV = 100 mgKOH / g, the reactivity becomes too low and the foam goes down during foaming, and a good foam is obtained. I couldn't. In Comparative Example 2, 100 parts by weight of EO = 80% by weight of polyol B1 was used, so that the reactivity was too high and excessive gas was generated to cause shrinkage, and a good foam could not be obtained. It was.

For Examples 1 to 14 and Comparative Examples 3 to 6 in which good foams were obtained, density (kg / m ³ , JIS K 7222: 1999 compliant), hardness (N, JIS K 6400- 2: 2004 D method), rebound resilience (%, JIS K 6400-3: 2004 compliant), 50% wet heat strain (%, JIS K 6400 compliant), air permeability (L / min, ASTM D 3574 compliant). It was measured. In addition, about the mold foaming product, the core (inner side from the skin) was cut out and measured. The measurement results are shown in the lower part of Tables 1 to 3.

  As understood from the measurement results, Examples 1 to 14 were higher in air permeability than Comparative Examples 3 to 6 having substantially the same density. Moreover, about Example, except Example 4 and Example 5, the Example had low hardness (soft) compared with all the comparative examples. Note that Example 4 and Example 5 were slightly harder than Comparative Example 5, but Comparative Example 5 was an open foamed product with extremely low hardness and was a molded foamed product. Compared with Comparative Example 3 and Comparative Example 4, Examples 4 and 5 have sufficiently low hardness. Since Example 4 has an isocyanate index of 95 and is high in the examples, it is relatively hard in the examples and has low air permeability. On the other hand, in Example 5, since the ratio of TDI / MDI is 50/50, in the examples, the density and altitude are relatively high, and the air permeability is low. In addition, with respect to 50% wet heat strain, the strain was less than all the comparative examples except for Example 5, Example 6, Example 8, and Example 9. In addition, although Example 5, Example 6, Example 8, and Example 9 were slightly larger distortion than Comparative Example 3 and Comparative Example 6, they are still sufficiently small in distortion.

As described above, the soft polyurethane foams of the examples have extremely high air permeability, and can suppress the occurrence of shrinkage particularly in molded foam products. This invention, oxy and polyol functionality 2 to 4 (A) is an ester condensate of fatty acids and polyfunctional alcohols, in the polyoxyalkylene chain a polyether polyol having a polyoxyalkylene chain A polyol (B) containing 45 to 85% by weight of an ethylene group is used in combination, and the polyol (A) has a structure mainly composed of hydrocarbons, while the polyol (B) is composed of oxyethylene groups. Since the ether group has less steric hindrance, the use of polyol (A) and polyol (B) with significantly different compatibility is considered to result in foam bubbles (cells) being easily broken. It is done. Moreover, it is thought that the combined use of the polyol (A) and the polyol (B) resulted in a thin resin skeleton of the foam and a soft polyurethane foam having low hardness. Furthermore, by including toluene diisocyanate in the polyisocyanate, a soft polyurethane foam having a lighter weight and a lower hardness can be obtained.

Claims (2)

In a polyurethane foam formed from a polyurethane raw material containing a polyol, a polyisocyanate, a foaming agent and a catalyst,
Wherein the polyol is a polyol derived from a polyol of functionality 2-4 consist ester condensates of fatty acids and polyfunctional alcohols vegetable oils (A), a polyether polyol having a polyoxyalkylene chain In combination with a polyol (B) containing 45 to 85% by weight of an oxyethylene group in the polyoxyalkylene chain,
The amount of the polyol (A) is 10 to 50 parts by weight in 100 parts by weight of the polyol.
The amount of the polyol (B) is 90 to 50 parts by weight which is the remaining amount obtained by subtracting the amount of the polyol (A) from 100 parts by weight of the polyol.
A polyurethane foam comprising at least toluene diisocyanate as the polyisocyanate. The polyisocyanate uses toluene diisocyanate (TDI) and diphenylmethane diisocyanate (MDI) in combination, and the weight ratio of TDI / MDI is 80/20,
The polyurethane foam according to claim 1, wherein the polyurethane foam has a hardness of 6 to 49 N (based on JIS K6400-2: 2004 D method).