Polyurethane foam and impact absorbing material

Abstract

This polyurethane foam is the reaction product of a raw material composition containing polyether polyol and an isocyanate, the polyether polyol containing a polyether polyol (A) having a hydroxyl value of 100 mgKOH / g or less and an ethylene oxide content of 50 mass% or more. The content of the polyether polyol (A) is 65-75 mass% with respect to the total amount of the polyether polyol, and the density of the polyurethane foam is 110 kg / m3 or more.

Description

Polyurethane foam and shock absorbing material

[0001] The present disclosure relates to polyurethane foams and impact absorbing materials.

[0002] Polyurethane foam is a foam obtained by mixing a polyol having a hydroxy group with a polyisocyanate having an isocyanate group, and causing a foaming reaction and a resinification reaction to occur simultaneously.

[0003] For example, Japanese Patent Application Laid-Open No. 2021-147461 describes a polyurethane foam obtained by reacting at least an isocyanate compound (I) containing two or more isocyanate groups per molecule, a polyol compound (II) as a chain extender, and a polyol (III) containing two or more hydroxyl groups per molecule, wherein the polyol (III) contains a polycarbonate polyol (A) having a structural unit derived from an oxyalkylene glycol represented by formula (A1). JP-A-2-175713 describes a method for producing a flexible polyurethane foam, characterized in that a mixture of a polyol, a catalyst, a foam stabilizer, a blowing agent, and other appropriate auxiliaries is reacted with a polyisocyanate to produce a polyurethane foam, using a polyether polyol having an average molecular weight of 400 to 2000 and an average functionality of 2 to 3.5 as the polyol. Japanese Patent Application Laid-Open No. 2001-40058 describes a method for producing polyurethane foam, which comprises adding a polyol, a catalyst, a blowing agent, an MDI-based prepolymer or a mixed prepolymer of another isocyanate and an MDI-based isocyanate so as to give an isocyanate index of 35 to 95, and then mixing and foaming the mixture.JP 2000-290344 A describes a flexible polyurethane foam obtained from an organic polyisocyanate (A), an active hydrogen compound (B), and a blowing agent, in which the active hydrogen compound (B) is (b1) a polyether polyol having a hydroxyl value of 40 mgKOH / g or more and 120 mgKOH / g or less, an average functionality of 2 to 4, and a molar addition polymerization ratio of alkylene oxide having 3 or more carbon atoms and ethylene oxide of 50 / 50 to 10 / 90; (b2) a polyether polyol having a hydroxyl value of 410 mgKOH / g or more and 600 mgKOH / g or less; (b1) a polyether polyol having an average functionality of 2 to 8 and a hydroxyl value of 20 mgKOH / g or less and 170 mgKOH / g or less, and an average functionality of 2 to 4; (b2) a polyether polyol having an average functionality of 2 to 4 and a hydroxyl value of 20 mgKOH / g or more and 170 mgKOH / g or less, and an average functionality of 2 to 4; a mixture in which, when the total weight of (b1), (b2), and (b3) is taken as 100, the mixing ratios of the respective components are (b1) 30 to 85, (b2) 5 to 50, and (b3) 10 to 40, or a polymer polyol obtained from the mixture.

[0004] However, the polyurethane foams described in the above documents do not have sufficient physical properties in terms of impact absorption and conformability. For example, if the proportion of low-molecular-weight polyol is increased in an attempt to improve impact absorption, the foam tends to become harder and the conformability tends to decrease.

[0005] In general, improving impact absorption is effective by making the polyurethane foam sufficiently thick or increasing its density. However, increasing the thickness of the polyurethane foam improves impact absorption but also increases its bulk. Increasing the density of the polyurethane foam also improves impact absorption but also increases its weight. Depending on the application of the polyurethane foam, thickness may be limited or weight reduction may be required, and a polyurethane foam with excellent impact absorption properties is desired even under such conditions.

[0006] The present disclosure has been made in consideration of the above circumstances, and an object of the present disclosure is to provide a polyurethane foam having excellent shock absorption and conformability, and an impact absorbing material including the polyurethane foam.

[0007] The present disclosure includes the following aspects: <1> A reaction product of a raw material composition containing a polyether polyol and an isocyanate, wherein the polyether polyol contains a polyether polyol (A) having a hydroxyl value of 100 mgKOH / g or less and an ethylene oxide content of 50 mass% or more, the content of the polyether polyol (A) is 65 to 75 mass% based on the total amount of the polyether polyol, and the density is 110 kg / m ３ or more. <2> The polyurethane foam according to claim 1, wherein the polyether polyol further comprises at least one selected from the group consisting of polyether polyol (B) having a hydroxyl value of 100 mgKOH / g or less and an ethylene oxide content of less than 50% by mass, and polyether polyol (C) having a hydroxyl value of 200 mgKOH / g or more and an ethylene oxide content of less than 50% by mass. <3> The polyurethane foam according to <1> or <2>, wherein the polyurethane foam has a rebound resilience of less than 15% in accordance with JIS K 6400-3. <4> The polyurethane foam according to any one of <1> to <3>, wherein the polyurethane foam has an Asker C hardness of less than 50. <5> An impact absorbing material comprising the polyurethane foam according to any one of <1> to <4>.

[0008] According to the present disclosure, there are provided a polyurethane foam having excellent shock absorption and conformability, and a shock absorbing material including the polyurethane foam.

[0009] In this specification, a numerical range indicated using "to" means a range that includes the numerical values ​​before and after "to" as the minimum and maximum values, respectively. In numerical ranges described in stages in this specification, the upper or lower limit value described in a certain numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. Furthermore, in numerical ranges described in this specification, the upper or lower limit value described in a certain numerical range may be replaced with a value shown in the examples. In this specification, when multiple substances corresponding to each component are present in the composition, the amount of each component in the composition means the total amount of the multiple substances present in the composition, unless otherwise specified. In this specification, a combination of two or more preferred embodiments is a more preferred embodiment. In this specification, the term "process" includes not only independent processes but also processes that cannot be clearly distinguished from other processes, as long as the intended purpose of the process is achieved.

[0010] [Polyurethane Foam] The polyurethane foam of the present disclosure is a reaction product of a raw material composition containing a polyether polyol and an isocyanate, the polyether polyol containing a polyether polyol (A) having a hydroxyl value of 100 mgKOH / g or less and an ethylene oxide content of 50 mass% or more, the content of the polyether polyol (A) being 65 to 75 mass% based on the total amount of the polyether polyol, and a density of 110 kg / m ３ That's all.

[0011] The polyurethane foam of the present disclosure can achieve both impact absorption and conformability.

[0012] The polyurethane foam of the present disclosure may be a molded polyurethane foam or a low-resilience molded polyurethane foam. Molded polyurethane foam is a polyurethane foam in which raw materials are poured into a mold with a lid and foamed and molded along the mold. Molded polyurethane foam is characterized by its ability to foam and mold in a short time.

[0013] The polyurethane foam of the present disclosure is a reaction product of a raw material composition containing a polyether polyol and an isocyanate. In addition to the polyether polyol and the isocyanate, the raw material composition may also contain at least one selected from a crosslinking agent, a catalyst, a foam stabilizer, and a blowing agent.

[0014] <Polyether polyol> The raw material composition contains at least one polyether polyol. The polyether polyol contained in the raw material composition contains a polyether polyol (A) having a hydroxyl value of 100 mg KOH / g or less and an ethylene oxide content of 50 mass% or more. Hereinafter, the ethylene oxide content may also be referred to as the "EO ratio."

[0015] (Polyether polyol (A)) The hydroxyl value of the polyether polyol (A) is 100 mgKOH / g or less, preferably 50 mgKOH / g or less, and more preferably 40 mgKOH / g or less. From the viewpoint of ease of mixing with other materials, the hydroxyl value of the polyether polyol (A) is preferably 20 mgKOH / g or more. When the hydroxyl value of the polyether polyol (A) is 100 mgKOH / g or less, a good polyurethane foam can be obtained.

[0016] In the present disclosure, the hydroxyl value is measured by a method in accordance with JIS K0070:1992.

[0017] The EO ratio of the polyether polyol (A) is 50% by mass or more, preferably 60% by mass or more, and more preferably 70% by mass or more. From the viewpoint of good foamability, the EO ratio of the polyether polyol (A) is preferably 80% by mass or less. When the EO ratio of the polyether polyol (A) is 50% by mass or more, the impact absorption property is particularly excellent.

[0018] In the present disclosure, the EO ratio means the content (% by mass) of ethylene oxide units in the polyether polyol (A) in terms of mass.

[0019] The polyether polyol (A) may contain alkylene oxide units other than ethylene oxide units. Examples of other alkylene oxide units include propylene oxide, butylene oxide, etc. The polyether polyol (A) preferably contains ethylene oxide units and propylene oxide units.

[0020] The number average molecular weight of the polyether polyol (A) is not particularly limited. From the viewpoints of ease of mixing of raw materials and spreadability, the number average molecular weight of the polyether polyol (A) is preferably 20,000 or less, more preferably 10,000 or less. From the viewpoints of moldability and conformability, the number average molecular weight of the polyether polyol (A) is preferably 1,000 or more, preferably 2,500 or more, and more preferably 4,000 or more.

[0021] In the present disclosure, the number average molecular weight is a polystyrene-equivalent value obtained by detecting by gel permeation chromatography (GPC) using an EXTREMA column (manufactured by JASCO Corporation) in tetrahydrofuran (THF) as a solvent and a differential refractometer, and converting the value using polystyrene as a standard substance. Note that catalog values ​​may also be used as the number average molecular weight.

[0022] The number of functional groups of the polyether polyol (A) is not particularly limited. From the viewpoints of reactivity and followability, the number of functional groups of the polyether polyol (A) is preferably 2 to 5, more preferably 2 to 4, and even more preferably 2 to 3.

[0023] In the present disclosure, the functionality refers to the average number of active hydrogen groups possessed by the polyether polyol. When the polyol is a commercially available product, the value listed in the catalog is used as the functionality.

[0024] The content of the polyether polyol (A) is 65 to 75% by mass based on the total amount of the polyether polyols.

[0025] When the content of polyether polyol (A) is within the above range, a polyurethane foam having excellent impact absorption and conformability can be obtained. When the content of polyether polyol (A) is 65% by mass or more, conformability and moldability are improved. When the content of polyether polyol (A) is 75% by mass or less, impact absorption is improved.

[0026] (Polyether Polyols (B) and (C)) The polyether polyol preferably further contains at least one selected from the group consisting of polyether polyol (B) having a hydroxyl value of 100 mgKOH / g or less and an EO ratio of less than 50 mass%, and polyether polyol (C) having a hydroxyl value of 200 mgKOH / g or more and an EO ratio of less than 50 mass%.

[0027] By further containing at least one selected from the group consisting of polyether polyol (B) and polyether polyol (C), a polyurethane foam having even more excellent impact absorption properties and conformability can be obtained.

[0028] In particular, the polyether polyol preferably contains polyether polyol (A), polyether polyol (B), and polyether polyol (C).

[0029] The hydroxyl value of the polyether polyol (B) is 100 mgKOH / g or less, preferably 50 mgKOH / g or less, and more preferably 40 mgKOH / g or less. From the viewpoint of moldability and conformability, the hydroxyl value of the polyether polyol (B) is preferably 20 mgKOH / g or more.

[0030] The hydroxyl value of the polyether polyol (C) is 200 mgKOH / g or more, preferably 300 mgKOH / g or more, and more preferably 400 mgKOH / g or more. From the viewpoint of conformability, the hydroxyl value of the polyether polyol (C) is preferably 600 mgKOH / g or less.

[0031] The EO ratio of the polyether polyol (B) is less than 50% by mass, preferably 35% by mass or less, and more preferably 20% by mass or less. From the viewpoint of reactivity, the EO ratio of the polyether polyol (B) is preferably 5% by mass or more.

[0032] The EO ratio of the polyether polyol (C) is less than 50% by mass, preferably 30% by mass or less, and more preferably 10% by mass or less, and may be 0% by mass.

[0033] The polyether polyol (B) may contain alkylene oxide units other than ethylene oxide units. Examples of other alkylene oxide units include propylene oxide and butylene oxide. The polyether polyol (B) preferably contains ethylene oxide units and propylene oxide units.

[0034] The polyether polyol (C) may contain alkylene oxide units other than ethylene oxide units, such as propylene oxide and butylene oxide.

[0035] The number average molecular weight of the polyether polyol (B) is not particularly limited. From the viewpoint of ease of mixing of raw materials and spreadability, the number average molecular weight of the polyether polyol (B) is preferably 20,000 or less, more preferably 10,000 or less. From the viewpoint of moldability, the number average molecular weight of the polyether polyol (B) is preferably 1,000 or more, more preferably 2,500 or more, and even more preferably 4,000 or more.

[0036] The number average molecular weight of the polyether polyol (C) is not particularly limited. From the viewpoints of moldability and low resilience, the number average molecular weight of the polyether polyol (C) is preferably 800 or less, more preferably 550 or less. From the viewpoints of moldability and conformability, the number average molecular weight of the polyether polyol (C) is preferably 200 or more, more preferably 300 or more, and even more preferably 350 or more.

[0037] The number of functional groups of the polyether polyol (B) is not particularly limited. From the viewpoints of reactivity and followability, the number of functional groups of the polyether polyol (B) is preferably 2 to 5, more preferably 2 to 4, and even more preferably 2 to 3.

[0038] The number of functional groups of the polyether polyol (C) is not particularly limited. From the viewpoints of reactivity and followability, the number of functional groups of the polyether polyol (C) is preferably 2 to 5, more preferably 2 to 4, and even more preferably 2 to 3.

[0039] The content of the polyether polyol (B) is preferably 5% by mass to 20% by mass, more preferably 10% by mass to 15% by mass, based on the total amount of the polyether polyols.

[0040] The content of the polyether polyol (C) is preferably 10% by mass to 25% by mass, and more preferably 15% by mass to 20% by mass, based on the total amount of the polyether polyols.

[0041] When the polyether polyol contains polyether polyol (B) and polyether polyol (C), the mass ratio of the content of polyether polyol (B) to the content of polyether polyol (C) (polyether polyol (B) / polyether polyol (C)) is preferably 0.45 to 0.90, more preferably 0.5 to 0.8. When the mass ratio is in the above range, the impact absorption and conformability are further improved.

[0042] <Isocyanate> The raw material composition contains at least one type of isocyanate. The isocyanate contained in the raw material composition is not particularly limited. The isocyanate may be a diphenylmethane diisocyanate (MDI)-based polyisocyanate or a toluene diisocyanate (TDI)-based polyisocyanate. Examples of MDI-based polyisocyanates include monomeric MDIs such as 2,2'-diphenylmethane diisocyanate (2,2'-MDI), 2,4'-diphenylmethane diisocyanate (2,4'-MDI), and 4,4'-diphenylmethane diisocyanate (4,4'-MDI); polymeric MDIs, which are mixtures of diphenylmethane diisocyanate and polymethylene polyphenylene polyisocyanate; and urethane-, carbodiimide-, urea-, allophanate-, biuret-, and isocyanurate-modified versions of these. The isocyanate may also be an MDI prepolymer obtained by reacting the above-mentioned MDI-based polyisocyanate with a polyol.

[0043] Examples of TDI-based polyisocyanates include 2,4-TDI, 2,6-TDI, and mixtures of 2,4-TDI and 2,6-TDI. The ratio of 2,4-TDI to 2,6-TDI (2,4-TDI / 2,6-TDI) is preferably 100 / 0 to 50 / 50 (mass ratio), more preferably 80 / 20 to 65 / 35.

[0044] Among these, the isocyanate preferably contains urethane-modified MDI.

[0045] The isocyanate index (INDEX) is preferably 90 to 110, more preferably 95 to 105, and even more preferably 96 to 103.

[0046] The isocyanate index is the value obtained by dividing the number of moles of isocyanate groups in an isocyanate by the total number of moles of active hydrogen groups such as hydroxyl groups of a polyol and water as a blowing agent, and multiplying the result by 100. That is, the isocyanate index is calculated by [NCO equivalent of isocyanate / active hydrogen equivalent × 100].

[0047] <Crosslinking Agent> The raw material composition may contain at least one crosslinking agent. The crosslinking agent has the effect of, for example, increasing the hardness of the polyurethane foam.

[0048] Examples of crosslinking agents include amines such as diethanolamine and polyethylene polyamines; and polyhydric alcohols such as trimethylolpropane, glycerin, 1,4-butanediol, and diethylene glycol. The number of functional groups in the crosslinking agent is preferably 2 to 4. The content of the crosslinking agent may be 1.0 to 2.0 parts by mass per 100 parts by mass of the polyether polyol. The content of the crosslinking agent is preferably 1.1 to 1.9 parts by mass, more preferably 1.2 to 1.8 parts by mass, even more preferably 1.3 to 1.7 parts by mass, and particularly preferably 1.4 to 1.6 parts by mass.

[0049] <Catalyst> The raw material composition may contain at least one catalyst. Examples of the catalyst include amine catalysts such as aliphatic amine catalysts and aromatic amine catalysts; and metal catalysts such as tin octoate. The content of the catalyst may be 0.5 parts by mass to 1.5 parts by mass per 100 parts by mass of the polyether polyol. The content of the catalyst is preferably 0.6 parts by mass to 1.4 parts by mass, more preferably 0.7 parts by mass to 1.3 parts by mass, even more preferably 0.8 parts by mass to 1.2 parts by mass, and particularly preferably 0.9 parts by mass to 1.1 parts by mass.

[0050] <Foam stabilizer> The raw material composition may contain at least one type of foam stabilizer. The foam stabilizer may be any foam stabilizer that is commonly used as a raw material for polyurethane foam. Examples of foam stabilizers include silicone compounds and nonionic surfactants. The content of the foam stabilizer may be 0 to 0.9 parts by mass per 100 parts by mass of polyether polyol. The content of the foam stabilizer is preferably 0.2 to 0.8 parts by mass, more preferably 0.3 to 0.7 parts by mass, even more preferably 0.4 to 0.6 parts by mass, and particularly preferably 0.45 to 0.55 parts by mass.

[0051] <Blowing Agent> The raw material composition may contain at least one blowing agent. Examples of blowing agents include water, alternatives to chlorofluorocarbons, and hydrocarbons such as pentane. Water is particularly preferred as the blowing agent. When water is used, carbon dioxide gas is generated during the reaction of the polyether polyol with the isocyanate, and foaming is carried out by the carbon dioxide gas. The content of water as the blowing agent may be 1.0 to 3.0 parts by mass per 100 parts by mass of polyetherol. The content of water as the blowing agent is preferably 1.2 to 2.8 parts by mass, more preferably 1.4 to 2.6 parts by mass, even more preferably 1.6 to 2.4 parts by mass, and particularly preferably 1.8 to 2.2 parts by mass.

[0052] <Other Components> The raw material composition may contain other components in addition to the above components. Examples of other components include a linking agent, a flame retardant, an antioxidant, etc.

[0053] <Physical Properties> The polyurethane foam according to the present disclosure may be a flexible polyurethane foam.

[0054] (Density) The density of the polyurethane foam is 110 kg / m ３ The density is 110 kg / m or more. ３ By satisfying the above, the impact absorption and conformability are excellent. ３ ~300 kg / m ３ Preferably, it is 125 kg / m ３ ~250 kg / m ３ More preferably, it is 140 kg / m ３ ~200 kg / m ３ It is more preferable that:

[0055] In the present disclosure, density is measured in accordance with JIS K7222:2005.

[0056] (Rebound resilience) The rebound resilience of the polyurethane foam is preferably less than 15%, more preferably 10% or less, and even more preferably 8% or less. The lower limit of the rebound resilience is not particularly limited, and is, for example, 4%.

[0057] In the present disclosure, the rebound resilience is measured in accordance with JIS K 6400-3:2011.

[0058] (Asker C Hardness) The Asker C hardness of the polyurethane foam is preferably less than 50, and more preferably not more than 40. The lower limit of the Asker C hardness is not particularly limited, and is, for example, 8.

[0059] In the present disclosure, the Asker C hardness is measured at 23°C in accordance with JIS K7312:1996.

[0060] <Method for producing polyurethane foam> Polyurethane foam can be produced by a known foaming method, for example, by stirring and mixing a raw material composition and reacting a polyether polyol and an isocyanate. Foaming methods include slab foaming and mold foaming. Either foaming method is acceptable, but mold foaming is preferred. Mold foaming is a method in which a mixed raw material composition is filled into a mold (forming die) and foamed within the mold. The method of producing molded urethane by mold foaming is suitable for producing molded products having complex three-dimensional shapes.

[0061] The thickness of the polyurethane foam to be produced is not particularly limited. When the foaming method is mold foaming, the thickness may be any thickness that can be produced by mold foaming. The thicker the polyurethane foam, the higher the impact absorption. However, the polyurethane foam of the present disclosure exhibits excellent impact absorption even when the thickness is about 10 mm.

[0062] <Applications> There are no limitations on the types of articles to which the polyurethane foam of the present disclosure can be applied. The polyurethane foam of the present disclosure is suitable for sports protectors or supports for joints such as elbows and knees; helmet protective pads, cushions, automobile headrests, armrests, motorcycle saddles, seats, bicycle saddles; clothing pads (e.g., bra pads); etc. In particular, the polyurethane foam of the present disclosure, which has excellent impact absorption and conformability even when having a thickness of 10 mm or less (e.g., 5 mm, 6 mm, 7 mm, 8 mm, or 9 mm), is suitable for members that support at least a part of the human body, such as protectors or supports for joints such as elbows and knees; helmet protective pads; clothing pads (e.g., bra pads).

[0063] [Impact Absorbing Material] The impact absorbing material of the present disclosure comprises the polyurethane foam of the present disclosure. The polyurethane foam of the present disclosure has excellent impact absorption and conformability, and therefore the impact absorbing material of the present disclosure has excellent impact absorption and conformability. Examples of impact absorbing materials include sports protectors or supports for joints such as elbows and knees; protective pads for helmets, cushions, automobile headrests, armrests, motorcycle saddles, seats, bicycle saddles; and clothing pads (e.g., bra pads).

[0064] Hereinafter, the present disclosure will be described in more detail with reference to examples, but the present disclosure is not limited to the following examples as long as it does not depart from the gist of the disclosure.

[0065] [Production of Polyurethane Foam] Raw material compositions were prepared by blending the raw materials in the proportions (parts by mass) shown in Table 1, and polyurethane foams were produced by mold foaming.

[0066] The details of the raw materials are as follows:

[0067] Polyether polyol (A): Product name "CP1421", manufactured by Dow Chemical Japan, EO rate 75% by mass, number of functional groups 3, hydroxyl value 35 mg KOH / g, number average molecular weight 5000 Polyether polyol (B): Product name "VORANOL4701", manufactured by Dow Chemical Japan, EO rate 14% by mass, number of functional groups 3, hydroxyl value 35 mg KOH / g, number average molecular weight 5000 Polyether polyol (C): Product name "SANNICS GP400", manufactured by Sanyo Chemical Industries, Ltd., EO rate 0% by mass, number of functional groups 3, hydroxyl value 421 mg KOH / g, number average molecular weight 400 Crosslinking agent (glycerin): Product name "Dynamite Glycerin", manufactured by NOF Corporation Catalyst: Amine catalyst, product name "DABCO 33LSI", manufactured by Evonik Japan Foam stabilizer: Silicone foam stabilizer, product name "TEGOSTAB B8738LF2", manufactured by Evonik Japan Co., Ltd. Isocyanate: Urethane-modified MDI, product name "Lupranate MP-102", manufactured by BASF INOAC Corporation, isocyanate index 100

[0068] Test pieces were cut out from the resulting polyurethane foam and used to measure density. Test pieces were also cut out from the resulting polyurethane foam and used to evaluate impact absorption, resilience, conformability, and moldability. The measurement and evaluation methods were as follows:

[0069] (Density) The density was measured in accordance with JIS K7222:2005.

[0070] (Impact Absorption) A drop weight test was conducted. Specifically, the maximum stress when a 5 kg iron ball was dropped from a height of 60 cm was measured. The evaluation criteria are as follows: A: The maximum stress is less than 20 kN. B: The maximum stress is 20 kN or more but less than 25 kN. C: The maximum stress is 25 kN or more.

[0071] (Resilience) Resilience modulus was measured in accordance with JIS K 6400-3:2011. Resilience was evaluated based on the resilience modulus. The evaluation criteria are as follows: A: Resilience modulus is less than 10%. B: Resilience modulus is 10% or more and less than 15%. C: Resilience modulus is 15% or more.

[0072] (Conformability) The Asker C hardness was measured at 23°C in accordance with JIS K7312:1996. The conformability was evaluated based on the Asker C hardness. The evaluation criteria are as follows: A: Asker C hardness is less than 40. B: Asker C hardness is 40 or more and less than 50. C: Asker C hardness is 50 or more.

[0073] (Moldability) Test pieces measuring 400 mm x 150 mm x 10 mm were prepared, and the state of the polyurethane foam was visually observed to evaluate moldability. Specifically, it was confirmed whether shrinkage occurred or whether dents were formed on the surface without crushing. The evaluation criteria are as follows: A: No problem with moldability at all. B: There are some problems with moldability, but it is at a level that is not problematic for practical use. C: There are problems with moldability.

[0074] The evaluation results are shown in Table 1. In Comparative Examples 4 and 8, molding was not possible, so the density could not be measured and further evaluation could not be performed. In Table 1, the density and evaluation columns are marked with "-".

[0075]

[0076] As shown in Table 1, in Examples 1 to 3, the polyurethane foams were reaction products of raw material compositions containing polyether polyol and isocyanate, the polyether polyol contained polyether polyol (A), the content of polyether polyol (A) was 65 to 75 mass%, and the density was 110 kg / m ３ From the above, it was found that the shock absorption and followability were excellent.

Claims

1. A reaction product of a raw material composition containing a polyether polyol and an isocyanate, wherein the polyether polyol contains a polyether polyol (A) having a hydroxyl value of 100 mgKOH / g or less and an ethylene oxide content of 50 mass% or more, the content of the polyether polyol (A) being 65 to 75 mass% based on the total amount of the polyether polyol, and the density being 110 kg / m ３ That's it, polyurethane foam.

2. The polyurethane foam according to claim 1, wherein the polyether polyol further comprises at least one selected from the group consisting of polyether polyol (B) having a hydroxyl value of 100 mg KOH / g or less and an ethylene oxide content of less than 50 mass%, and polyether polyol (C) having a hydroxyl value of 200 mg KOH / g or more and an ethylene oxide content of less than 50 mass%.

3. The polyurethane foam according to claim 1 or 2, which has a rebound resilience of less than 15% in accordance with JIS K 6400-3.

4. The polyurethane foam according to any one of claims 1 to 3, having an Asker C hardness of less than 50.

5. A shock absorbing material comprising the polyurethane foam according to any one of claims 1 to 4.

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