WO2025197147A1 - Polyurethane foam and impact absorbing material - Google Patents

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

This disclosure relates to polyurethane foams and impact absorbing materials.

Polyurethane foam is a foam obtained by mixing a polyol containing hydroxyl groups with a polyisocyanate containing isocyanate groups, causing a foaming reaction and a resinification reaction to occur simultaneously.

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 in one molecule, a polyol compound (II) as a chain extender, and a polyol (III) containing two or more hydroxyl groups in one molecule, wherein the polyol (III) contains a polycarbonate polyol (A) having a structural unit derived from an oxyalkylene glycol represented by formula (A1).
Japanese Patent Laid-Open Publication No. 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 the polyurethane foam, and the polyol used is a polyether polyol having an average molecular weight of 400 or more and 2,000 or less and an average number of functional groups of 2 or more and 3.5 or less.
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.

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 rubber tends to become harder and its conformability tends to decrease.

In addition, 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 makes it bulky. Increasing the density of the polyurethane foam also improves impact absorption but makes it heavier. Depending on the application of polyurethane foam, thickness may be limited or weight reduction may be required, and polyurethane foam with excellent impact absorption even under such conditions is required.

This disclosure was made in consideration of the above circumstances, and aims to provide a polyurethane foam with excellent shock absorption and conformability, and a shock absorbing material comprising the polyurethane foam.

The present disclosure includes the following aspects.
<1>
A reaction product of a raw material composition containing a polyether polyol and an isocyanate,
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 polyols;
A polyurethane foam having a density of 110 kg/m3 or ^more .
<2>
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 mass%, and polyether polyol (C) having a hydroxyl value of 200 mgKOH/g or more and an ethylene oxide content of less than 50 mass%.
<3>
<1> or <2>, wherein the polyurethane foam has a rebound resilience of less than 15% in accordance with JIS K 6400-3.
＜4＞
<4> The polyurethane foam according to any one of <1> to <3>, having an Asker C hardness of less than 50.
<5>
<1><4> An impact absorbing material comprising the polyurethane foam according to any one of <1> to <4>.

The present disclosure provides a polyurethane foam with excellent shock absorption and conformability, and a shock absorbing material comprising the polyurethane foam.

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 the 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 the 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, the amount of each component in a composition means the total amount of the multiple substances present in the composition, unless otherwise specified, when multiple substances corresponding to each component are present in the composition.
In this specification, a combination of two or more preferred aspects is a more preferred aspect.
In this specification, the term "process" includes not only an independent process but also a process that cannot be clearly distinguished from other processes, as long as the intended purpose of the process is achieved.

[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 the density being 110 kg/ ^m3 or more.

The polyurethane foam disclosed herein provides both shock absorption and conformability.

The polyurethane foam disclosed herein may be molded polyurethane foam or low-resilience molded polyurethane foam. Molded polyurethane foam is a polyurethane foam in which raw materials are injected into a mold with a lid, and the foam is expanded and molded along the mold. Molded polyurethane foam is characterized by its ability to expand and mold in a short period of time.

The polyurethane foams of the present disclosure are the reaction product of a raw material composition comprising a polyether polyol and an isocyanate.
The raw material composition may contain, in addition to the polyether polyol and the isocyanate, at least one selected from a crosslinking agent, a catalyst, a foam stabilizer, and a foaming agent.

<Polyether polyol>
The raw material composition includes at least one polyether polyol. The polyether polyol included in the raw material composition includes 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."

(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.

In this disclosure, hydroxyl value is measured using a method in accordance with JIS K0070:1992.

The EO ratio of 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 foaming properties, the EO ratio of polyether polyol (A) is preferably 80% by mass or less. When the EO ratio of polyether polyol (A) is 50% by mass or more, particularly excellent impact absorption properties are achieved.

In this disclosure, the EO ratio refers to the mass-equivalent content (mass%) of ethylene oxide units in polyether polyol (A).

The polyether polyol (A) may contain alkylene oxide units other than ethylene oxide units, such as propylene oxide and butylene oxide.
The polyether polyol (A) preferably contains ethylene oxide units and propylene oxide units.

The number average molecular weight of the polyether polyol (A) is not particularly limited. From the viewpoints of ease of mixing the raw materials and spreadability, the number average molecular weight of the polyether polyol (A) is preferably 20,000 or less, and more preferably 10,000 or less. Furthermore, 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.

In this disclosure, the number average molecular weight is a polystyrene-equivalent value measured by gel permeation chromatography (GPC) using an EXTREMA (manufactured by JASCO Corporation) column, with detection using THF (tetrahydrofuran) as the solvent and a differential refractometer, and converted using polystyrene as the standard substance. Note that catalog values may also be used for the number average molecular weight.

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

In this disclosure, functionality refers to the average number of active hydrogen groups possessed by the polyether polyol. If the polyol is a commercially available product, the catalog value is used as the functionality.

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

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

(Polyether polyols (B) and (C))
It is preferable that the polyether polyol 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%.

By further including at least one selected from the group consisting of polyether polyol (B) and polyether polyol (C), a polyurethane foam with superior impact absorption and conformability can be obtained.

In particular, it is preferable that the polyether polyol includes polyether polyol (A), polyether polyol (B), and polyether polyol (C).

The hydroxyl value of 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 standpoint of moldability and conformability, the hydroxyl value of polyether polyol (B) is preferably 20 mgKOH/g or more.

The hydroxyl value of polyether polyol (C) is 200 mg KOH/g or more, preferably 300 mg KOH/g or more, and more preferably 400 mg KOH/g or more. From the standpoint of followability, the hydroxyl value of polyether polyol (C) is preferably 600 mg KOH/g or less.

The EO ratio of 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 standpoint of reactivity, the EO ratio of polyether polyol (B) is preferably 5% by mass or more.

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

The polyether polyol (B) may contain alkylene oxide units other than ethylene oxide units, such as propylene oxide and butylene oxide.
The polyether polyol (B) preferably contains ethylene oxide units and propylene oxide units.

Polyether polyol (C) may contain alkylene oxide units other than ethylene oxide units. Examples of other alkylene oxide units include propylene oxide, butylene oxide, etc.

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

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, and more preferably 550 or less. Furthermore, 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.

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

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

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

The content of 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 polyether polyol.

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, and more preferably 0.5 to 0.8. When the mass ratio is within the above range, impact absorption and conformability are further improved.

<Isocyanate>
The raw material composition includes at least one isocyanate. The isocyanate included 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-modified, carbodiimide-modified, urea-modified, allophanate-modified, biuret-modified, 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.

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.

Among these, it is preferable that the isocyanate contains urethane-modified MDI.

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

The isocyanate index is calculated by dividing the number of moles of isocyanate groups in an isocyanate by the total number of moles of active hydrogen groups from the hydroxyl groups of the polyol and the water used as a blowing agent, etc., and multiplying the result by 100. In other words, the isocyanate index is calculated as [NCO equivalent of isocyanate / active hydrogen equivalent x 100].

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

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

<Catalyst>
The feed composition may include 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 catalyst content may be 0.5 parts by mass to 1.5 parts by mass relative to 100 parts by mass of polyether polyol, 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.

<Foam stabilizer>
The raw material composition may contain at least one foam stabilizer.
The foam stabilizer may be any foam stabilizer that is commonly used as a raw material for polyurethane foam, such as silicone compounds and nonionic surfactants.
The content of the foam stabilizer may be 0 to 0.9 parts by mass relative to 100 parts by mass of the polyether polyol, 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.

<Blowing Agent>
The feed composition may also include at least one blowing agent.
Examples of the blowing agent 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 between polyether polyol and isocyanate, and foaming is carried out by the carbon dioxide gas.
The content of water as a blowing agent may be 1.0 to 3.0 parts by mass relative to 100 parts by mass of polyetherol, 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.

<Other ingredients>
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, and an antioxidant.

<Physical properties>
The polyurethane foam according to the present disclosure may be a flexible polyurethane foam.

(density)
The density of the polyurethane foam is 110 kg/m ³ or more.
When the density is 110 kg/m ³ or more, the shock absorption property and the followability are excellent.
The density is preferably 110 kg/m ³ to 300 kg/m ³ , more preferably 125 kg/m ³ to 250 kg/m ³ , and even more preferably 140 kg/m ³ to 200 kg/m ³ .

In this disclosure, density is measured in accordance with JIS K7222:2005.

(Rebound elasticity)
The polyurethane foam preferably has a rebound resilience of 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%.

In this disclosure, the rebound resilience is measured in accordance with JIS K 6400-3:2011.

(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.

In this disclosure, Asker C hardness is measured at 23°C in accordance with JIS K7312:1996.

<Method of manufacturing 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 molded urethane foaming method using mold foaming is suitable for producing molded products with complex three-dimensional shapes.

There are no particular limitations on the thickness of the polyurethane foam produced. If mold foaming is used, the thickness should be one that can be produced by mold foaming. The thicker the polyurethane foam, the higher its impact absorption. However, the polyurethane foam of the present disclosure exhibits excellent impact absorption even when it is approximately 10 mm thick.

<Application>
There are no particular 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 and 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 its thickness is 10 mm or less (e.g., 5 mm, 6 mm, 7 mm, 8 mm, or 9 mm), is suitable for components 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; and clothing pads (e.g., bra pads).

[Shock absorbing material]
The shock absorbing material of the present disclosure comprises the polyurethane foam of the present disclosure.
Since the polyurethane foam of the present disclosure has excellent shock absorption and conformability, the impact absorbing material of the present disclosure has excellent shock 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; clothing pads (e.g., bra pads); and the like.

The present disclosure will be explained in more detail below using examples, but the present disclosure is not limited to the following examples as long as they do not deviate from the gist of the disclosure.

[Production of polyurethane foam]
A raw material composition was prepared by blending the raw materials in the proportions (parts by mass) shown in Table 1, and a polyurethane foam was produced by mold foaming.

Details of the ingredients are as follows:

Polyether polyol (A): Product name "CP1421", manufactured by Dow Chemical Japan, EO ratio 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 ratio 14% by mass, number of functional groups 3, hydroxyl value 35 mg KOH/g, number average molecular weight 5000
Polyether polyol (C): Product name "Sannyx GP400", manufactured by Sanyo Chemical Industries, Ltd., EO ratio 0 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 Co., Ltd. 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.

Test pieces were cut out from the resulting polyurethane foam, and the density was measured using the test pieces.
Test pieces were cut out from the resulting polyurethane foam, and the test pieces were used to evaluate impact absorption, resilience, conformability, and moldability. The measurement and evaluation methods were as follows.

(density)
The density was measured in accordance with JIS K7222:2005.

(shock absorption)
A drop weight test was carried out. Specifically, a 5 kg iron ball was dropped from a height of 60 cm, and the maximum stress was measured. The evaluation criteria were as follows:
A: The maximum stress is less than 20 kN.
B: The maximum stress is 20 kN or more and less than 25 kN.
C: The maximum stress is 25 kN or more.

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

(Follow-up ability)
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 were 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.

(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 without crushing and whether dents were formed on the surface. The evaluation criteria were as follows:
A: There is no problem with formability.
B: There are some problems with formability, but it is at a level that does not pose any problems in practical use.
C: There is a problem with moldability.

Table 1 shows the evaluation results. Note that in Comparative Examples 4 and 8, molding was not possible, so density could not be measured and further evaluation was not possible. In Table 1, the density and evaluation columns are marked with "-."

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 or ^more , and therefore it was found that the polyurethane foams had excellent impact absorption properties and conformability.

Claims (5)

A reaction product of a raw material composition containing a polyether polyol and an isocyanate,
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;
A polyurethane foam having a density of 110 kg/m3 or ^more . 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%. The polyurethane foam according to claim 1 or claim 2, having a resilience coefficient of less than 15% in accordance with JIS K 6400-3. The polyurethane foam according to any one of claims 1 to 3, having an Asker C hardness of less than 50. An impact absorbing material comprising the polyurethane foam described in any one of claims 1 to 4.