Polyurethane foam, impact absorber, and method for producing polyurethane foam

Abstract

This polyurethane foam comprises: a first structural unit derived from a first biomass-derived polyol having fewer than 2.5 functional groups and a number-average molecular weight of at least 1500; and a second structural unit derived from a second biomass-derived polyol having fewer than 2.5 functional groups and a number-average molecular weight of less than 1500.

Description

Polyurethane foam, shock absorber, method for manufacturing polyurethane foam

[0001] This invention relates to polyurethane foam, shock absorbers, and methods for manufacturing polyurethane foam.

[0002] In recent years, the technology of using biomass raw materials in polyurethane foam has attracted attention as a so-called carbon-neutral renewable resource to contribute to the formation of a sustainable society. Polyurethane foam, which is produced by foaming polyurethane, is widely used in various fields. Polyurethane is a polymer compound having a urethane bond (-NH-C(=O)O-) and is obtained by reacting the hydroxyl group of a polyol with the isocyanate group of a polyisocyanate.

[0003] Polyurethane foams include high-rebound polyurethane foams with enhanced rebound elasticity and low-rebound polyurethane foams with reduced rebound elasticity. In other words, polyurethane foams are adjusted to have appropriate rebound elasticity depending on the application.

[0004] International Publication No. 2007 / 020905 discloses a plant-derived polyurethane foam that uses plant-derived polyols with side chain number, functional group number, and hydroxyl value within a specific range, contributing to the reduction of environmental impact and possessing excellent low resilience, particularly avoiding hardness increase at low temperatures. Japanese Patent Publication No. 2018-016748 discloses a low-resilience polyurethane foam manufactured using multiple polyols with different molecular weights, functional group number, and hydroxyl value. Japanese Patent Publication No. 2020-084173 discloses a polyurethane foam with excellent shock absorption obtained from a polyurethane raw material containing a polyol component (which may be a plant-derived polyol), a polyisocyanate component, and a foaming gas. Japanese Patent Publication No. 2011-528727 discloses a polyol composition containing hydroxymethylated fatty acids and hydroxymethylated esters derived from natural resources, and discloses the manufacture of a viscoelastic polyurethane foam using the polyol composition.

[0005] Furthermore, Japanese Patent Publication No. 2012-036354 discloses the production of highly productive integral skin foam while maintaining a high utilization rate of plant-derived components, with castor oil or castor oil derivatives used in the polyol accounting for 40% by mass or more (relative to the polyol). Japanese Patent Publication No. 2021-188032 discloses the production of flexible polyurethane foam using modified castor oil polyol and unmodified castor oil polyol as the polyol component.

[0006] As mentioned above, while the technology for using biomass raw materials in polyurethane foam is known, there was no known polyurethane foam made from biomass raw materials that could maintain flexibility at low temperatures. Therefore, this disclosure aims to provide a polyurethane foam, an impact absorber, and a method for manufacturing polyurethane foam that use biomass-derived polyols, have excellent shock absorption properties, and can maintain flexibility at low temperatures.

[0007] To achieve the above-mentioned objectives, the inventors conducted diligent research and found that by using a combination of multiple biomass-derived polyols with different number-average molecular weights, it is possible to produce a polyurethane foam that has excellent shock absorption and maintains flexibility even at low temperatures, thus completing this disclosure. This disclosure includes the following: <1> A polyurethane foam comprising a first structural unit derived from a first biomass-derived polyol having less than 2.5 functional groups and a number-average molecular weight of 1500 or more, and a second structural unit derived from a second biomass-derived polyol having less than 2.5 functional groups and a number-average molecular weight of less than 1500. <2> The polyurethane foam according to <1>, further comprising a third structural unit derived from a third biomass-derived polyol having 2.5 or more functional groups. <3> A polyurethane foam with a density of 100 kg / m³ ３The polyurethane foam described in <1> or <2> above. <4> The polyurethane foam described in any one of <1> to <3>, which contains an inorganic filler. <5> An impact absorber comprising the polyurethane foam described in any one of <1> to <4>. <6> A method for producing polyurethane foam, comprising the step of reacting a first biomass-derived polyol having less than 2.5 functional groups and a number average molecular weight of 1500 or more with a second biomass-derived polyol having less than 2.5 functional groups and a number average molecular weight of less than 1500 with a polyisocyanate component. <7> A method for producing polyurethane foam described in <6>, comprising the step of mixing foaming gas into the raw materials.

[0008] Furthermore, this disclosure includes: <8> A polyurethane foam according to any one of <1> to <4>, wherein the isocyanate index is 90 to 110. <9> A polyurethane foam according to any one of <1> to <4> and <8>, wherein the glass transition temperature is 15°C to 35°C. <10> A polyurethane foam according to any one of <1> to <4>, <8> and <9>, wherein the impact load in the impact absorption test is 25 kN or less. <11> A method for producing a polyurethane foam according to <6> or <7>, wherein in the reaction step, the first biomass-derived polyol, the second biomass-derived polyol, and the polyisocyanate component are mixed so that the isocyanate index is 90 to 110. <12> A method for producing a polyurethane foam according to any one of <6>, <7> and <11>, wherein the glass transition temperature of the polyurethane foam is 15°C to 35°C. <13> A method for manufacturing polyurethane foam according to any one of <6>, <7>, <11>, and <12>, wherein the impact load in the impact absorption test of the polyurethane foam is 25 kN or less. <14> An impact absorbing material according to <5> that is used in an environment with an ambient temperature of 0°C or lower.

[0009] Furthermore, this disclosure includes: <15> A polyurethane foam made from a biomass-derived polyol, characterized in that it uses a first biomass-derived polyol having less than 2.5 functional groups and a number average molecular weight of 1500 or more, and a second biomass-derived polyol having less than 2.5 functional groups and a number average molecular weight of less than 1500. <16> The polyurethane foam according to <15>, further comprising a third biomass-derived polyol having 2.5 or more functional groups. <17> A polyurethane foam with a density of 100 kg / m³ ３ The polyurethane foam described in <15> or <16> above. <18> The polyurethane foam described in any one of <15> to <17>, which contains an inorganic filler.

[0010] Furthermore, this disclosure also includes: <19> A polyurethane foam composition comprising a first biomass-derived polyol having less than 2.5 functional groups and a number average molecular weight of 1500 or more, a second biomass-derived polyol having less than 2.5 functional groups and a number average molecular weight of less than 1500, and a polyisocyanate. <20> The polyurethane foam composition according to <19>, further comprising a third biomass-derived polyol having 2.5 or more functional groups. <21> The polyurethane foam composition according to <19> or <20>, further comprising an inorganic filler.

[0011] According to this disclosure, it is possible to provide a polyurethane foam, an impact absorber, and a method for manufacturing the polyurethane foam, which use biomass-derived polyols and have excellent shock absorption properties and maintain flexibility even at low temperatures.

[0012] The embodiments are described in detail below. However, this disclosure is not limited to the embodiments described below. In the embodiments described below, the components (including elemental steps, etc.) are not essential unless otherwise specified. The same applies to numerical values ​​and their ranges, and do not limit this disclosure.

[0013] In this disclosure, the term "process" includes not only processes that are independent of other processes, but also processes that cannot be clearly distinguished from other processes, provided that the purpose of the process is achieved. In this disclosure, numerical ranges indicated using "~" include the numbers before and after "~" as the minimum and maximum values, respectively. In numerical ranges described in stages in this disclosure, the upper or lower limit of one numerical range may be replaced with the upper or lower limit of another numerical range described in stages. Also, in a described numerical range, the upper or lower limit of that range may be replaced with the value shown in the example. In this disclosure, each component may contain multiple types of the corresponding substance. If multiple types of the substance corresponding to each component are present in the composition, the content or amount of each component means the total content or amount of the multiple types of substances present in the composition, unless otherwise specified. In this disclosure, each component may contain multiple types of particles. If multiple types of particles corresponding to each component are present in the composition, the particle size of each component means the value for a mixture of the multiple types of particles present in the composition, unless otherwise specified.

[0014] In this disclosure, "polyol" means a compound having two or more hydroxyl groups in its molecule. In this disclosure, "polyisocyanate" means a compound having two or more isocyanate groups in its molecule. In this disclosure, "urethane foam" means a polyurethane foam which is a reaction product of a polyol and a polyisocyanate. The urethane foam may have open cells, closed cells, or a combination of open and closed cells.

[0015] In this disclosure, the quantity-average molecular weight of the compounds is measured by gel permeation chromatography (GPC) and expressed as a value converted to standard polystyrene.

[0016] In this disclosure, a monomer derived from a structural unit in a polymer refers to a compound whose structure is obtained by replacing the urethane bond in the main chain of the polymer with a hydroxyl group and an isocyanate group, and separating it from other structural units. Structural units in a polymer are bonded to each other by urethane bonds between the hydroxyl group of the monomer and the isocyanate group of the monomer. Furthermore, unless otherwise specified, structural units in a polymer are bonded to each other by covalent bonds. It is sufficient that the polymer has a "derived structural unit," and it is irrelevant whether it actually originates from that monomer. Specifically, for example, if the structure of a part of the polymer other than the main chain structure corresponding to the urethane bond, such as a functional group such as a carboxyl group, is changed by a chemical reaction, the structural unit is classified based on the chemical structure after the change.

[0017] In this disclosure, biomass refers to organic resources derived from living organisms such as plants, animals, and microorganisms. Specifically, biomass includes waste biomass, unused biomass, and resource crop biomass. Furthermore, in this disclosure, biomass percentage is a value calculated as the proportion (%) of biomass-derived raw materials to the total mass of all raw materials. The biomass percentage can be calculated using the following formula: Biomass percentage (%) = (Mass of biomass material / Mass of total raw materials) × 100.

[0018] 1. Polyurethane Foam The polyurethane foam of this disclosure comprises a first structural unit derived from a first biomass-derived polyol having fewer than 2.5 functional groups and a number average molecular weight of 1500 or more, and a second structural unit derived from a second biomass-derived polyol having fewer than 2.5 functional groups and a number average molecular weight of less than 1500. The polyurethane foam of this disclosure has the characteristics of excellent shock absorption and the ability to maintain flexibility even at low temperatures. Here, shock absorption is judged from the impact load when a 21 mm thick test piece is made using the polyurethane foam to be tested and a 5.3 kg weight is dropped onto the test piece from a height of 1.2 m (ambient temperature 22°C). When measured with an ICP type impact load cell (model: 200C20) manufactured by PCB Piezotronics, the polyurethane foam is judged to have excellent shock absorption if the load is 25 kN or less. Furthermore, flexibility can be determined by preparing a 3 mm thick sample using the polyurethane foam under test, bending the sample 180° in a -10°C environment, and checking whether cracks or fractures occur. If no cracks or fractures occur in the sample in a -10°C environment, it is determined that the flexibility can be maintained at low temperatures.

[0019] Furthermore, the polyurethane foam of this disclosure may further contain a third structural unit derived from a third biomass-derived polyol having 2.5 or more functional groups. That is, the polyurethane foam of this disclosure may contain a first structural unit derived from the first biomass-derived polyol, a second structural unit derived from the second biomass-derived polyol, and a third structural unit derived from the third biomass-derived polyol.

[0020] Hereinafter, the first biomass-derived polyol, the second biomass-derived polyol, and the third biomass-derived polyol may be collectively referred to as "biomass-derived polyol." In the polyurethane foam of this disclosure, the content of biomass-derived polyol is not particularly limited, as long as it has the characteristic of maintaining flexibility even at low temperatures. The lower limit of the biomass-derived polyol content can be, for example, 10% by mass or more, preferably 20 parts by mass or more, more preferably 25 parts by mass or more, and even more preferably 30 parts by mass or more, when the total polyol components are considered to be 100% by mass. Furthermore, in the polyurethane foam of this disclosure, the upper limit of the biomass-derived polyol content can be, for example, 100 parts by mass or less, 90 parts by mass or less, 80 parts by mass or less, and 70 parts by mass or less. In the polyurethane foam of this disclosure, by setting the biomass-derived polyol content within this range, the characteristic of maintaining flexibility even at low temperatures can be achieved.

[0021] Furthermore, by setting the content of biomass-derived polyols in the polyurethane foam of this disclosure to this range, a high biomass content and environmentally friendly polyurethane foam can be obtained. In particular, the biomass content in the polyurethane foam of this disclosure is preferably 20% or more, more preferably 30% or more, even more preferably 40% or more, and even more preferably 45% or more. Note that the above biomass content is the value contributed by biomass-derived polyols. If biomass-derived components can be used in other components constituting the polyurethane foam of this disclosure, the above biomass content will be an even higher value due to the contribution of those other components.

[0022] (1) Biomass-derived polyols In this disclosure, biomass-derived polyols are not particularly limited as long as they are derived from biomass. In particular, it is preferable to use plant-derived polyols derived from plant resources as biomass-derived polyols. Examples of plant-derived polyols include natural oil-derived polyols. Natural oil-derived polyols are natural oils or derivatives thereof (modified natural oil polyols, unmodified natural oil polyols, etc.) such as castor oil, soybean oil, rapeseed oil, coconut oil, sunflower oil, linseed oil, cottonseed oil, tuna oil, poppy oil, corn oil, cashew nut shell oil, etc., which contain hydroxyl groups on the hydrocarbon chain and have two or more hydroxyl groups in one molecule. Examples of plant-derived polyols include 1,3-propanediols derived from plants and animals such as corn.

[0023] As plant-derived polyols, castor oil having secondary hydroxyl groups and its derivatives are preferred. Furthermore, as derivatives of castor oil, modified castor oil polyols such as ester-modified castor oil polyols are preferred. In this specification, "castor oil" includes unmodified castor oil, modified castor oil, dehydrated castor oil, hydrogenated castor oil, etc. Here, unmodified castor oil is an ester of fatty acid and glycerol. Unmodified castor oil mainly consists of ricinoleic acid, and other components include, for example, unsaturated fatty acids such as oleic acid, linoleic acid, and linolenic acid, and saturated fatty acids such as palmitic acid and stearic acid.

[0024] (1-1) First Biomass-Derived Polyol The first biomass-derived polyol in this disclosure is a biomass-derived polyol having less than 2.5 functional groups and a number-average molecular weight of 1500 or more. Here, the number of functional groups refers to the number of reactive groups (hydroxyl groups that can react with isocyanate groups) that a single molecule has. The number of functional groups is calculated as the average value of the biomass-derived polyol used. In the first biomass-derived polyol in this disclosure, the number of functional groups is less than 2.5, but is preferably 2.3 or less, and more preferably 2.0. In addition, the number of functional groups in the first biomass-derived polyol is 2.0 or more.

[0025] In the first biomass-derived polyol in this disclosure, the number average molecular weight is 1500 or more, preferably 1700 or more, more preferably 2000 or more, and even more preferably 2400 or more. Furthermore, in the first biomass-derived polyol in this disclosure, the number average molecular weight is preferably 4000 or less, more preferably 3500 or less, and even more preferably 3000 or less. Having the number average molecular weight of the first biomass-derived polyol in this disclosure within this range allows the excellent effects of the polyurethane foam in this disclosure, such as excellent shock absorption and maintaining flexibility even at low temperatures, to be fully exhibited.

[0026] The content of the first biomass-derived polyol in the polyurethane foam of this disclosure is not particularly limited, but can be in the range of 10% to 30% by mass, preferably in the range of 10% to 25% by mass, more preferably in the range of 15% to 25% by mass, and even more preferably in the range of 18% to 24% by mass, when the total polyol component is considered to be 100% by mass. By having the content of the first biomass-derived polyol in this disclosure within this range, the excellent effects of the polyurethane foam of this disclosure, such as excellent shock absorption and maintaining flexibility even at low temperatures, can be fully exhibited.

[0027] (1-2) Second Biomass-Derived Polyol The second biomass-derived polyol in this disclosure is a biomass-derived polyol having less than 2.5 functional groups and a number-average molecular weight of less than 1500. The number of functional groups is as defined in (1-1) First Biomass-Derived Polyol above. In the second biomass-derived polyol in this disclosure, the number of functional groups is less than 2.5, but is preferably 2.3 or less, and more preferably 2.0. In the second biomass-derived polyol, the number of functional groups is 2.0 or more.

[0028] In the second biomass-derived polyol in the present disclosure, the number average molecular weight is less than 1500, but can be 1100 or less, can be 800 or less, and can be 600 or less. Further, the number average molecular weight of the second biomass-derived polyol in the present disclosure is preferably 500 or more, more preferably 700 or more, and even more preferably 1000 or more.

[0029] When the number average molecular weight of the second biomass-derived polyol in the present disclosure is within this range, the excellent effects of the polyurethane foam of the present disclosure, such as excellent shock absorption and maintaining flexibility even at low temperatures, can be fully exerted.

[0030] The content of the second biomass-derived polyol in the polyurethane foam of the present disclosure is not particularly limited, but when the total of the polyol components is 100% by mass, it can be in the range of 10% to 30% by mass, preferably in the range of 10% to 25% by mass, more preferably in the range of 10% to 20% by mass, and even more preferably in the range of 14% to 20% by mass. When the content of the second biomass-derived polyol in the present disclosure is within this range, the excellent effects of the polyurethane foam of the present disclosure, such as excellent shock absorption and maintaining flexibility even at low temperatures, can be fully exerted.

[0031] Further, in the polyurethane foam of the present disclosure, the total content of the first biomass-derived polyol and the second biomass-derived polyol is not particularly limited, but when the total of the polyol components is 100% by mass, it is preferably in the range of 20% to 50% by mass, more preferably in the range of 25% to 45% by mass, and even more preferably in the range of 30% to 40% by mass. When the total content of the first biomass-derived polyol and the second biomass-derived polyol in the present disclosure is within this range, the excellent effects of the polyurethane foam of the present disclosure, such as excellent shock absorption and maintaining flexibility even at low temperatures, can be fully exerted.

[0032] (1-3) Polyol Derived from the Third Biomass The polyol derived from the third biomass in the present disclosure is a biomass-derived polyol having a functionality of 2.5 or more. The functionality is as defined in the column of the above (1-1) polyol derived from the first biomass. In the polyol derived from the third biomass of the present disclosure, the functionality is 2.5 or more, and can be 2.7 or more, and can be 3.0 or more. Further, in the polyol derived from the third biomass, the functionality is preferably 6.0 or less, more preferably 5.0 or less, still more preferably 4.0 or less, and still more preferably 3.0 or less.

[0033] In the polyol derived from the third biomass in the present disclosure, the number average molecular weight is not particularly limited, but can be 2000 or less, can be 1500 or less, can be 1000 or less, and can be 900 or less. Further, the number average molecular weight of the polyol derived from the second biomass in the present disclosure is preferably 500 or more, more preferably 700 or more, still more preferably 800 or more, and still more preferably 900 or more.

[0034] In the polyurethane foam of the present disclosure, when the total of the polyol components is 100% by mass, the polyol derived from the third biomass is preferably 60% by mass or less, more preferably 57% by mass or less, and still more preferably 55% by mass or less. By setting the content of the polyol derived from the third biomass within this range in the polyurethane foam of the present disclosure, while fully exhibiting the excellent effects of the polyurethane foam of the present disclosure, such as excellent shock absorbency and maintaining flexibility even at low temperatures, the biomass content in the polyurethane foam can be maintained high.

[0035] (2) Polyols other than biomass-derived polyols The polyurethane foam of this disclosure may be used in combination with polyols other than biomass-derived polyols that can be used in the manufacture of polyurethane foam. One or more types of polyols other than biomass-derived polyols can be freely selected. Examples of polyols other than plant-derived polyols include polyester polyols, polycarbonate polyols, polyether polyols, polyester ether polyols, polymer polyols, etc.

[0036] Examples of polyester polyols include aliphatic dicarboxylic acids such as succinic acid, adipic acid, sebacic acid, and azelaic acid; aliphatic carboxylic acids such as ricinoleic acid; aromatic dicarboxylic acids such as phthalic acid, terephthalic acid, isophthalic acid, and naphthalenedicarboxylic acid; alicyclic dicarboxylic acids such as hexahydrophthalic acid, hexahydroterephthalic acid, and hexahydroisophthalic acid; or acid esters or acid anhydrides thereof, and ethylene glycol, 1,3-propylene glycol, 1,2-propylene glycol, and 1,3-butylene glycol. Examples of polyester polyols include polypropylene glycol obtained by dehydration condensation reactions with polynediols such as 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, 1,8-octanediol, 1,9-nonanediol, etc., or mixtures thereof; and polylactone polyols and polycaprolactone polyols obtained by ring-opening polymerization of lactone monomers such as ε-caprolactone and methylvalerolactone. In addition to these, examples of polyester polyols include polyols having naturally derived ester groups.

[0037] Examples of polycarbonate polyols include those obtained by reacting at least one polyhydric alcohol, such as ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, 1,8-octanediol, 1,9-nonanediol, or diethylene glycol, with diethylene carbonate, dimethyl carbonate, diethyl carbonate, or the like.

[0038] Examples of polyether polyols include polyethylene glycol, polypropylene glycol, polytetramethylene ether glycol, and their copolyethers, which are obtained by polymerizing cyclic ethers such as ethylene oxide, propylene oxide, and tetrahydrofuran, respectively. They can also be obtained by polymerizing the above-mentioned cyclic ethers using polyhydric alcohols such as glycerin and trimethylolethane.

[0039] Examples of polyester ether polyols include aliphatic dicarboxylic acids such as succinic acid, adipic acid, sebacic acid, and azelaic acid; aromatic dicarboxylic acids such as phthalic acid, terephthalic acid, isophthalic acid, and naphthalenedicarboxylic acid; alicyclic dicarboxylic acids such as hexahydrophthalic acid, hexahydroterephthalic acid, and hexahydroisophthalic acid; or those obtained by dehydration condensation reactions of these acid esters or acid anhydrides with glycols such as diethylene glycol or propylene oxide adducts, or mixtures thereof.

[0040] Polymer polyols are those obtained by polymerizing ethylenically unsaturated monomers in a polyol, or by emulsifying and dispersing polymers of ethylenically unsaturated monomers in a polyol. Specifically, examples include those obtained by graft polymerization of acrylonitrile, styrene, etc., into a polyol, or those obtained by dispersing polystyrene or polyacrylonitrile in a polyol.

[0041] In addition, in the polyurethane foam of this disclosure, polyols other than biomass-derived polyols also include polyethylene glycol (PEG), dipropylene glycol (DPG), etc., which are added as chain extenders.

[0042] In the polyurethane foam of this disclosure, the content of polyols other than biomass-derived polyols is not particularly limited, as long as it allows the polyurethane foam to exhibit its excellent effects, such as superior shock absorption and maintaining flexibility even at low temperatures. For example, the content of polyols other than biomass-derived polyols in the polyurethane foam of this disclosure can be 0.5% to 20% by mass, preferably 0.5% to 15% by mass, and preferably 2.0% to 15% by mass, when the total polyol component is considered to be 100% by mass. By setting the content of polyols other than biomass-derived polyols within this range, it is possible to maintain a high biomass content in the polyurethane foam while fully exhibiting the excellent effects of the polyurethane foam of this disclosure, such as maintaining flexibility even at low temperatures.

[0043] (3) Polyisocyanates The polyisocyanates can be known aromatic isocyanates, alicyclic isocyanates, or aliphatic isocyanates used in the manufacture of polyurethane foam. Examples of aromatic isocyanates include 1,5-naphthalene diisocyanate (NDI), tolylene diisocyanate (TDI), 4,4'-diphenylmethane diisocyanate (MDI), polymeric MDI (crude MDI), xylylene diisocyanate, and dimethyl biphenyl diisocyanate (TODI). Examples of alicyclic isocyanates include cyclohexane-1,4-diisocyanate, isophorone diisocyanate, and hydrogenated MDI. Examples of aliphatic isocyanates include hexamethylene diisocyanate, isopropyl diisocyanate, and methylene diisocyanate.

[0044] In particular, it is preferable to use monomeric MDI or carbodiimide-modified MDI, which is obtained by modifying monomeric MDI with carbodiimide, as the polyisocyanate. Carbodiimide-modified MDI is preferred because it is a liquid at room temperature, easier to handle than monomeric MDI which is a solid at room temperature, and more flexible than polymeric MDI.

[0045] In the polyurethane foam of this disclosure, the isocyanate index (INDEX) is preferably 90 to 110, more preferably 95 to 110, even more preferably 100 to 110, and even more preferably 103 to 110, from the viewpoint of achieving the desired mechanical strength and low rebound properties. The isocyanate index is an index used in the field of polyurethane foams, and is a numerical value expressed as a percentage of the equivalent ratio of isocyanate groups to active hydrogen groups in a polyurethane foam composition [equivalent of NCO groups / equivalent of active hydrogen groups × 100].

[0046] (4) The polyurethane foam of this disclosure may contain a nucleating agent. The nucleating agent is an additive that has the function of being the starting point for foam nuclei in the process of forming the polyurethane foam. Foam nuclei are more easily formed at the interface between the nucleating agent and the liquid raw material. As a result, fine bubbles can be uniformly formed within the foam. In this disclosure, the type of nucleating agent is not particularly limited as long as it performs the above-described function, but inorganic fillers can be mentioned. That is, as a nucleating agent, for example, (a) aluminum hydroxide (Al(OH) ３ ), magnesium hydroxide (Mg(OH) ２ ), calcium hydroxide (Ca(OH) ２ Examples of fillers include (b) metal hydroxides such as (c) , (d) talc, (e) light calcium carbonate, heavy calcium carbonate, calcium carbonate, (c) core-shell rubber particles, and (f) silica powder. Any one of these may be used as the filler, or two or more may be used.

[0047] The inorganic filler content can be in the range of 0% to 30% by mass, preferably in the range of 0% to 25% by mass, more preferably in the range of 0% to 20% by mass, and even more preferably in the range of 0% to 15% by mass, when the total raw materials of the polyurethane foam of this disclosure are considered to be 100% by mass. By setting the inorganic filler content within this range, it is possible to fully exhibit the excellent effects of the polyurethane foam of this disclosure, such as excellent impact resistance and maintaining flexibility even at low temperatures, while maintaining a high biomass content in the polyurethane foam.

[0048] (5) Foam stabilizers The polyurethane foam of this disclosure may contain foam stabilizers. Foam stabilizers facilitate the dispersion of entrained gases, stabilize bubbles, and adjust the bubble structure when mechanically foaming the raw material mixture. The type of foam stabilizer is not particularly limited in this disclosure. Examples of foam stabilizers include silicone-based foam stabilizers and fluorine-containing compound-based foam stabilizers. The foam stabilizer may be one of these types or two or more types.

[0049] (6) Catalyst The polyurethane foam of this disclosure may contain a catalyst. The catalyst is an additive for promoting the resinification reaction. The type of catalyst is not particularly limited in this disclosure. Examples of catalysts include amine catalysts and metal catalysts. Examples of amine catalysts include N,N-dimethylcyclohexylamine, N,N-dimethylbenzylamine, N,N-dimethylaminoethanol, N,N',N'-trimethylaminoethylpiperazine, and triethylenediamine. Examples of metal catalysts include (a) Sn-based catalysts such as stanus octoate and dibutyltin dilaurate, (b) Hg-based catalysts such as phenylmercury propionate, (c) Pb-based catalysts such as lead octenoate, (d) Fe-based catalysts such as iron acetylacetonate, and (e) Ni-based catalysts such as nickel acetylacetonate, nickel octoate, and nickel naphthenate. The catalyst may be one of these types or two or more types.

[0050] (7) Desiccants The polyurethane foam of this disclosure may contain desiccants. Desiccants are additives for removing moisture that inevitably gets mixed into the raw material mixture. When foaming is performed using the mechanical flossing method described later, if moisture gets mixed into the raw material mixture, the water and polyisocyanate react, and CO ２ This occurs. As a result, it becomes difficult to control the bubbles, and it may be difficult to form fine bubbles uniformly. The desiccant can suppress the unintended reaction between water and polyisocyanate. This makes it possible to form fine bubbles uniformly. In this disclosure, the type of desiccant is not particularly limited. Examples of desiccant include zeolite, silica powder, alumina powder, lithium hydroxide powder, barium hydroxide powder, calcium chloride powder, etc. The desiccant may be one of these or two or more.

[0051] 2. Method for Manufacturing Polyurethane Foam The method for manufacturing polyurethane foam according to this disclosure is not particularly limited, but includes the step of reacting the first biomass-derived polyol, the second biomass-derived polyol, and the polyisocyanate component as described above. In the method for manufacturing polyurethane foam according to this disclosure, the method for foaming the polyurethane is not particularly limited, and examples include a chemical foaming method using a compound having an active hydrogen group as a foaming agent, and a mechanical flossing method in which a foaming gas is mixed into the raw materials. In particular, in the method for manufacturing polyurethane foam according to this disclosure, it is preferable to manufacture the polyurethane foam by applying the mechanical flossing method. The compound having an active hydrogen group used in the chemical foaming method is a substance that generates foaming gas by heating or reaction, and an example is water that reacts with polyisocyanate to generate carbon dioxide gas.

[0052] Furthermore, in the mechanical flossing method, it is preferable to mix a raw material mixture containing the aforementioned biomass-derived polyol, polyisocyanate, and other components while mixing a foaming gas such as an inert gas or dry air into the raw materials using a high-shear mixer (step of mixing foaming gas into the raw materials). This makes it possible to obtain a foaming raw material mixture containing fine bubbles, and the polyurethane foam of this disclosure can be manufactured by applying the obtained foaming raw material mixture containing fine bubbles to the surface of a substrate (e.g., a PET film), heating the coating to a predetermined temperature, and curing it. In this method, it is preferable to include the foaming gas in the raw material mixture such that its mixing ratio is 31% to 91% by volume. The mixing ratio of the foaming gas refers to the volume percentage of the foaming gas relative to 100 parts by volume of the raw material mixture excluding the foaming gas. The polyurethane foam may also be molded by filling a so-called mold with the raw material mixture and foaming it within the mold.

[0053] 3. Physical Properties and Applications of Polyurethane Foam The physical properties of the polyurethane foam disclosed herein include excellent shock absorption and flexibility at low temperatures. In other words, the polyurethane foam disclosed herein has excellent shock absorption and can maintain the flexibility it has in an environment of, for example, 5°C to 30°C, even in a low-temperature environment where the ambient temperature is 0°C or below, preferably -5°C or below, and more preferably -10°C or below. The flexibility of the polyurethane foam can be determined by preparing a 3 mm thick sample using the polyurethane foam to be tested, bending the sample 180° in an environment of -10°C, and seeing if a crack or break occurs. If no crack or break occurs in the sample in an environment of -10°C, it is determined that the flexibility can be maintained at low temperatures. Furthermore, the shock absorption is determined from the impact load when a 5.3 kg weight is dropped from a height of 1.2 m onto a test piece made of the polyurethane foam to be tested, with a thickness of 21 mm (ambient temperature 22°C). When measured with a PCB Piezotronics ICP-type impact load cell (model: 200C20), the material is judged to have excellent shock absorption properties when the load is 25 kN or less.

[0054] Since the polyurethane foam of the present disclosure has such physical properties, it can be applied to various uses even in a low-temperature environment. As an example of the use of the polyurethane foam of the present disclosure, an impact absorber can be mentioned, and particularly an impact absorber used even in a low-temperature environment can be mentioned. Here, more specific embodiments of the impact absorber can include sports protectors, vehicle seats, medical protection pads, packaging materials for electronic devices, and the like. By using the polyurethane foam of the present disclosure, specific embodiments of these impact absorbers can be realized without cracks or fractures even in a low-temperature environment.

[0055] In addition, the physical properties of the polyurethane foam of the present disclosure can be appropriately set according to other uses and the like. In particular, the polyurethane foam of the present disclosure preferably has the following physical properties.

[0056] <Density> The density of the polyurethane foam of the present disclosure is not particularly limited, but is preferably in the range of 100 kg / m ３ to 700 kg / m ３ More preferably, it is in the range of 100 kg / m ３ to 500 kg / m ３ Even more preferably, it is in the range of 100 kg / m ３ to 350 kg / m ３ Also, the density of the polyurethane foam of the present disclosure is more preferably in the range of 120 kg / m [[ID=,20]]<() ３ to 700 kg / m ３ Even more preferably, it is in the range of 150 kg / m ３ to 70() kg / m ３ In particular, the density of the polyurethane foam of the present disclosure is more preferably in the range of 120 kg / m ３ to 500 kg / m [[ID=,30]] ３ Even more preferably, it is in the range of 150 kg / m ３ to 350 kg / m ３It is even more preferable that the density is within the above range. By having the lower limit of the density of the polyurethane foam of this disclosure be within the above range, for example, low rebound properties suitable for the various applications described above can be ensured. Furthermore, by having the upper limit of the density of the polyurethane foam of this disclosure be within the above range, for example, low rebound properties suitable for the various applications described above can be ensured. When manufacturing the polyurethane foam of this disclosure, the density of the polyurethane foam can be adjusted by adjusting the amount of foaming gas introduced to control the amount of bubbles in the polyurethane foam.

[0057] □The density of the polyurethane foam disclosed herein shall be measured according to JIS K 6401:2011. Specifically, a 50 × 50 mm rectangular prism-shaped test specimen shall be prepared, the thickness of the test specimen shall be measured using a thickness gauge, and the mass of the test specimen shall be measured using an electronic balance. The density shall be given by the following formula: Density [kg / mm] ３ ] = (mass of test specimen [g] / volume of test specimen [mm] ３ ]) × 10 ６ We will find it using this method.

[0058] <Tensile Strength> The tensile strength of the polyurethane foam of this disclosure is not particularly limited, but is preferably 0.4 MPa or higher, more preferably 0.6 MPa or higher, even more preferably 0.8 MPa or higher, and even more preferably 1.0 MPa or higher. Having the tensile strength of the polyurethane foam of this disclosure within this range ensures strength suitable for the various applications described above, for example.

[0059] □The tensile strength of the polyurethane foam disclosed herein shall be measured according to JIS K 6251:2010. Specifically, a dumbbell-shaped specimen (No. 3) shall be prepared, and the specimen shall be pulled at a tensile speed of 200 mm / min, and the maximum tensile force [N] until the specimen breaks shall be measured. The tensile strength is given by the following formula: Tensile strength [MPa] = Maximum force [N] / Area of ​​the parallel portion of the specimen [mm²] ２ ] is used to find it.

[0060] <Elongation> The elongation of the polyurethane foam of this disclosure is not particularly limited, but is preferably 150% or more, more preferably 170% or more, even more preferably 190% or more, even more preferably 200% or more, and even more preferably 210% or more. The elongation of the polyurethane foam of this disclosure is within this range, which ensures strength and durability suitable for the various applications described above.

[0061] □The elongation of the polyurethane foam disclosed herein shall be measured according to JIS K 6251:2010. Specifically, a dumbbell-shaped specimen (No. 3) shall be prepared, the specimen shall be pulled at a tensile speed of 200 mm / min, and the gauge length at the time of cutting shall be measured. The elongation shall be calculated using the following formula: Elongation at cutting [%] = ((Gauge length at cutting [mm] - Initial gauge length [mm]) / Initial gauge length [mm]) × 100.

[0062] <Tear Strength> The tear strength of the polyurethane foam of this disclosure is not particularly limited, but is preferably 1.4 MPa or higher, more preferably 1.7 MPa or higher, even more preferably 2.0 MPa or higher, and even more preferably 2.5 MPa or higher. Having the tear strength of the polyurethane foam of this disclosure within this range ensures strength suitable for the various applications described above, for example.

[0063] □The tear strength of the polyurethane foam disclosed herein shall be measured according to JIS K 6252:2007. Specifically, a test specimen shall be prepared by punching it into an angle shape using a punching machine, and its thickness shall be measured using a dial-type thickness gauge. Then, the test specimen shall be placed in a testing machine, and the test specimen shall be pulled at a tensile speed of 200 mm / min, and the tear stress shall be measured. The tear strength shall be calculated using the following formula: Tear strength [mPa] = (Maximum tensile force [N]) / Test specimen thickness [mm]).

[0064] <25% CLD> The 25% CLD (Compression-Load-Deflection) of the polyurethane foam of this disclosure is not particularly limited, but is preferably 0.06 MPa or less, more preferably 0.05 MPa or less, even more preferably 0.04 MPa or less, even more preferably 0.03 MPa or less, and even more preferably 0.02 MPa or less. Having the 25% CLD of the polyurethane foam of this disclosure within this range ensures, for example, low rebound and hardness suitable for the various applications described above.

[0065] The 25% CLD of the polyurethane foam disclosed herein is measured according to JIS K 6254. Specifically, a cylindrical test specimen with a diameter of φ50 mm is prepared, the specimen is compressed at a rate of 1.0 mm / min, and the relationship between compressive force and deflection is recorded. From the recorded compressive force-deformation curve, the compressive force at which the deflection reaches 25% relative to the thickness of the specimen before compression is calculated as the 25% CLD value using the following formula: Formula: 25% CLD [MPa] = (Compressive force at 25% deflection [N]) / (Area of ​​the specimen [mm²]) ２ ])

[0066] <Compression Residual Set> The compression residual set of the polyurethane foam of this disclosure is not particularly limited, but is preferably 4.5% or less, more preferably 4.0% or less, even more preferably 3.5% or less, and still more preferably 3.0% or less. Having the compression residual set of the polyurethane foam of this disclosure within this range ensures, for example, low resilience and dimensional stability suitable for the various applications described above.

[0067] The compression set of the polyurethane foam disclosed herein is measured according to JIS K 6401:2011. Specifically, a 50 x 50 mm rectangular prism-shaped test specimen is prepared, and the initial thickness of the specimen [T0] is measured using a thickness gauge. Then, a compression set jig is used to set a spacer equal to 50% of the initial thickness, the jig is tightened with screws (in three places), and the jig is left in a constant temperature bath at 70°C for 22 hours. After that, the jig is removed from the constant temperature bath and the test specimen is taken out. After leaving the removed test specimen at room temperature for 30 minutes, the thickness of the test specimen is measured again [T1]. The compression set is calculated using the following formula: ((T0 - T1) / T0) × 100.

[0068] <Impact Absorption Test> The impact load measured in the impact absorption test of the polyurethane foam of this disclosure is not particularly limited, but is preferably 25 kN or less, more preferably 23 kN or less, even more preferably 20 kN or less, and even more preferably 18 kN or less. By having the impact load of the polyurethane foam of this disclosure within this range, it is possible to ensure low resilience and strength suitable for the various applications described above, for example.

[0069] In the impact absorption test of the polyurethane foam described herein, a weight is dropped in free fall, and the impact load (kN) received by a sensor beneath the test specimen is confirmed. Specifically, a test specimen with a thickness of 21 mm is prepared, and a 5.3 kg weight is dropped onto the specimen from a height of 1.2 m (ambient temperature 22°C). At this time, the impact load is measured by the sensor described above.

[0070] <Glass Transition Temperature> The glass transition temperature of the polyurethane foam of this disclosure is not particularly limited, but is preferably 15°C to 35°C, more preferably 18°C ​​to 30°C, and even more preferably 20°C to 25°C or higher. Having a glass transition temperature within this range allows the polyurethane foam of this disclosure to have particularly excellent shock absorption properties suitable for the various applications described above.

[0071] The glass transition temperature of the polyurethane foam disclosed herein was measured using a TA Instruments ARES-G2 rheometer in the temperature range of -40°C to 80°C (heating rate: 3°C / min) in parallel plate mode (8 mmφ), with a strain of 0.5% and a frequency of 1.0 Hz. The glass transition temperature was measured as the temperature at the peak of tanδ.

[0072] The present disclosure will be described in more detail below with reference to examples, but the technical scope of the present disclosure is not limited to the following examples.

[0073] 1. The following raw materials were prepared to manufacture the polyurethane foams of the example and comparative example of polyurethane foam production. Specifically, ・Biomass ester polyol 1 (deodorized and refined castor oil, hydroxyl value: 163, number of functional groups: 2.70, number average molecular weight: 929, biomass content: 100%; polyol derived from third biomass), ・Biomass ester polyol 2 (castor oil-based polyester polyol, hydroxyl value: 200, number of functional groups: 3.00, number average molecular weight: 842, biomass content: 90%; polyol derived from third biomass), ・Biomass ester polyol 3 (castor oil-based polyester polyol, hydroxyl value: 45.8, number of functional groups: 2.00, number average molecular weight: 2450, biomass content: 95%; polyol derived from first biomass), • Biomass ester polyol 4 (castor oil (adipic acid-based polyester polyol), hydroxyl value: 225.5, number of functional groups: 2.00, number average molecular weight: 500, biomass content: 70%; polyol derived from secondary biomass), • Biomass ester polyol 5 (castor oil (sebacic acid-based polyester polyol), hydroxyl value: 109.1, number of functional groups: 2.00, number average molecular weight: 1028, biomass content: 100%; polyol derived from secondary biomass), • Ether polyol 1 (polypropylene triol, hydroxyl value: 280, number of functional groups: 3.00, number average molecular weight: 600), • Ester polyol 2 (adipic acid-based polyester polyol, hydroxyl value: 213, number of functional groups: 2.00, number average molecular weight: 529), - Polymer polyol 1 (manufactured by Mitsui Chemicals, Inc., product name: AN-230, hydroxyl value: 30.6, number of functional groups: 2.00, number average molecular weight: 3000), - Polymer polyol 2 (manufactured by Mitsui Chemicals, Inc., product name: AN-340, hydroxyl value: 43.5, number of functional groups: 3.00, number average molecular weight: 3000),

[0074] • Chain extender (dipropylene glycol, hydroxyl value: 837, number of functional groups: 2.00, number average molecular weight: 134), • Hydrophobic silica dispersed ether polyol (manufactured by Sanyo Shikiso Co., Ltd., product name: UT CLEAR AG1032, hydroxyl value: 56, number of functional groups: 2.00, number average molecular weight: 2000), • Foam stabilizer (silicone-based foam stabilizer, hydroxyl value: 40, number of functional groups: 1.00, number average molecular weight: 1400), • Catalyst 1 (iron catalyst, hydroxyl value: 56.1, number of functional groups: 2.00, number average molecular weight: 2000), • Catalyst 2 (nickel catalyst, hydroxyl value: 41.9, number of functional groups: 3.00, number average molecular weight: 3000), • Antioxidant (manufactured by Songwon Industrial Co., Ltd., product name: SONGNOX) 1135), ・Aluminum hydroxide 1 (manufactured by Almorix, Inc., product name: B-325), ・Aluminum hydroxide 2 (manufactured by Sumitomo Chemical Co., Ltd., product name: C-31), ・Calcium carbonate (manufactured by Shiraishi Calcium Co., Ltd., product name: Silver W), ・Desiccant (synthetic zeolite, manufactured by Union Showa Co., Ltd., product name: 3A MS), ・Pigment 1 (manufactured by Sanyo Shikkei Co., Ltd., product name: AE 619, hydroxyl value: 40.4, number of functional groups: 3.00, number average molecular weight: 3000), ・Coloring agent (manufactured by Milliken Japan LLC, product name: Reactint Red X64), ・Carbodiimide-modified MDI (manufactured by Tosoh Corporation, product name: MTL-S, NCO%: 30.88, number of functional groups: 2.15, number average molecular weight: 292, polyisocyanate component), ・Pure MDI (BASF A sample manufactured by INOAC Polyurethane Co., Ltd., product name: MI, NCO% 33.57, number of functional groups: 2.00, number average molecular weight: 252, polyisocyanate component) was prepared. Note that "NCO%" indicates the mass percentage of isocyanate groups.

[0075] Then, a composition was prepared by blending the raw materials in the proportions shown in Table 1. Air (foaming gas) was added to this composition, and the polyurethane foam of the example was produced by reacting the first biomass-derived polyol, the second biomass-derived polyol, and the polyisocyanate component. Details of each raw material are as follows. In Table 1, "-" means that the raw material was not included.

[0076]

[0077] 2. Evaluation Method The density, tensile strength, elongation, tear strength, 25% CLD, compressive residual strain, impact load, glass transition temperature, cracks, and branching number were measured using the manufactured polyurethane foam as follows.

[0078] <Density> The density was measured according to JIS K 6401:2011. Specifically, a 50 x 50 mm rectangular prism was prepared as a test specimen, the thickness of the specimen was measured using a thickness gauge, and the mass of the specimen was measured using an electronic balance. The density is given by the following formula: Density [kg / mm] ３ ] = (mass of test specimen [g] / volume of test specimen [mm] ３ ]) × 10 ６ I calculated it using this method.

[0079] <Tensile Strength> □Tensile strength was measured according to JIS K 6251:2010. Specifically, a dumbbell-shaped specimen (No. 3) was prepared, and the specimen was pulled at a tensile speed of 200 mm / min. The maximum tensile force [N] until the specimen broke was measured. Tensile strength is given by the following formula: Tensile strength [MPa] = Maximum force [N] / Area of ​​the parallel portion of the specimen [mm²] ２ This was calculated using [the formula / method].

[0080] <Elongation> Elongation was measured according to JIS K 6251:2010. Specifically, a dumbbell-shaped specimen (No. 3) was prepared, and the specimen was pulled at a tensile speed of 200 mm / min. The distance between the gauge marks at the time of cutting was measured. Elongation was calculated using the following formula: Elongation at cutting [%] = ((Distance between gauge marks at cutting [mm] - Initial distance between gauge marks [mm]) / Initial distance between gauge marks [mm]) × 100.

[0081] <Tear Strength> □Tear strength was measured according to JIS K 6252:2007 standards. Specifically, test specimens were prepared by punching them into an angle shape using a punching machine, and their thickness was measured using a dial-type thickness gauge. Then, the test specimens were placed in a testing machine and pulled at a tensile speed of 200 mm / min, and the tear stress was measured. The tear strength was calculated using the following formula: Tear strength [mPa] = (Maximum tensile force [N]) / Test specimen thickness [mm]).

[0082] <25% CLD> Measured according to JIS K 6254 standard. That is, a cylindrical test specimen with a diameter of φ50 mm is prepared, the specimen is compressed at a speed of 1.0 mm / min, and the relationship between compressive force and deflection is recorded. From the recorded compressive force-deformation curve, the compressive force at which the deflection reaches 25% relative to the thickness of the specimen before compression is calculated as the 25% CLD value using the following formula: Formula: 25% CLD [MPa] = (Compressive force at 25% deflection [N]) / (Area of ​​the specimen [mm²]) ２ ])

[0083] <Compression Residual Strain> Compression residual strain was measured according to JIS K 6401:2011 standards. Specifically, a 50 x 50 mm rectangular prism-shaped test specimen was prepared, and the initial thickness of the specimen [T0] was measured using a thickness gauge. Then, a compression residual strain jig was used to set a spacer equal to 50% of the initial thickness, the jig was tightened with screws (in 3 places), and it was left in a constant temperature bath at 70°C for 22 hours. After that, the jig was removed from the constant temperature bath and the test specimen was taken out. After leaving the removed test specimen at room temperature for 30 minutes, the thickness of the test specimen was measured again [T1]. Compression residual strain was calculated using the following formula: ((T0 - T1) / T0) × 100.

[0084] <Impact Absorption Test> In the impact absorption test, a weight was allowed to free-fall, and the impact load (kN) received by the sensor below the test specimen was confirmed. Specifically, a test specimen with a thickness of 21 mm was prepared, and a 5.3 kg weight was free-dropped onto the specimen from a height of 1.2 m (ambient temperature 22°C). At this time, the impact load was measured using the sensor mentioned above.

[0085] <Glass Transition Temperature> The glass transition temperature was measured using a TA Instruments ARES-G2 rheometer in the temperature range of -40°C to 80°C (heating rate: 3°C / min) in parallel plate mode (8 mmφ), with a strain of 0.5% and a frequency of 1.0 Hz. The glass transition temperature was measured as the temperature at the peak of tanδ.

[0086] <Cracking> To test for cracking, a 3 mm thick test specimen was prepared using the polyurethane foam under test. The specimen was then bent 180° in a -10°C environment, and the presence or absence of cracks or fractures was observed. A circle (○) indicated that no cracks or fractures occurred, while a cross (×) indicated that cracks or fractures occurred.

[0087] <Number of Branches> When the isocyanate index (hereinafter, INDEX) is 100 or less, the number of branches is calculated using the following formula: Number of branches (units / moles) = Σ (number of polyol functional groups - 2) × (number of polyol added parts / molecular weight) × (INDEX / 100) + (number of isocyanate added parts / molecular weight) × (number of isocyanate functional groups - 2). When the INDEX exceeds 100, the number of branches is calculated using the following formula: Number of branches (units / moles) = Σ (number of polyol functional groups - 2) × (number of polyol added parts / molecular weight) + (number of isocyanate functional groups) × (number of moles of isocyanate) × (1 - (100 / INDEX)) + number of moles of isocyanate × (number of isocyanate functional groups - 2).

[0088] 3. Results The polyurethane foams of Examples 1 to 11 use a first biomass-derived polyol (biomass ester polyol 3) with fewer than 2.5 functional groups and a number average molecular weight of 1500 or more, and a second biomass-derived polyol (biomass ester polyol 4 or biomass ester polyol 5) with fewer than 2.5 functional groups and a number average molecular weight of 1500 or less. All of these polyurethane foams of Examples 1 to 11 showed impact absorption results of 25 kN or less in the impact absorption test, and all passed the "cracking" test in the physical property evaluation, demonstrating excellent impact absorption and flexibility in low-temperature environments.

[0089] The disclosure of Japanese Patent Application No. 2024-229156, filed on 25 December 2024, is incorporated herein by reference in its entirety. Furthermore, all documents, patent applications, and technical standards described herein are incorporated by reference to the same extent as if each individual document, patent application, and technical standard were specifically and individually noted as being incorporated by reference.

Claims

1. A polyurethane foam comprising a first structural unit derived from a first biomass-derived polyol having fewer than 2.5 functional groups and a number-average molecular weight of 1500 or more, and a second structural unit derived from a second biomass-derived polyol having fewer than 2.5 functional groups and a number-average molecular weight of less than 1500.

2. The polyurethane foam according to claim 1, further comprising a third structural unit derived from a third biomass-derived polyol having 2.5 or more functional groups.

3. Density of 100 kg / m³ ３ The polyurethane foam described in claim 1 is as described above.

4. The polyurethane foam according to claim 1, comprising an inorganic filler.

5. An impact absorbing material comprising the polyurethane foam described in any one of claims 1 to 4.

6. A method for producing polyurethane foam, comprising the step of reacting a first biomass-derived polyol having fewer than 2.5 functional groups and a number average molecular weight of 1500 or more with a second biomass-derived polyol having fewer than 2.5 functional groups and a number average molecular weight of less than 1500 with a polyisocyanate component.

7. A method for producing polyurethane foam according to claim 6, comprising the step of mixing foaming gas into the raw materials.

Images