Curable composition, polyurethane resin composition, and polyurethane molded body

Abstract

This curable composition contains: a lignin component containing at least two compounds represented by formula (1); and a polyol, wherein the content of the lignin component is at least 0.1 mass%, and the total content of the compounds is at least 0.06 mass% with respect to the total amount of the lignin component. (In the formula, Ra is a hydrogen atom, a methyl group, an ethyl group, a furyl group, a hydroxymethylfuryl group, a hydroxyphenyl group, a hydroxymethoxyphenyl group, or a hydroxydimethoxyphenyl group. Rc1 and Rc2 each independently represent a hydroxyl group, an alkoxy group, an amino group, or a thiol group. R11-R20 each independently represent a hydrogen atom, a hydroxyl group, a C1-C15 hydrocarbon group, a C1-C15 hydrocarbon ether group, or a group containing a carbonyl group. R11-R20 may be the same as or different from each other. Here, at least one among R11-R15 is a hydrogen atom, and at least one among R16-R20 is a hydrogen atom.)

Description

Curable composition, polyurethane resin composition, and polyurethane molded article

[0001] The present invention relates to a curable composition used in the production of polyurethane, and a polyurethane molded article produced using the same.

[0002] In recent years, from the viewpoint of reducing environmental impact, attempts have been made to replace a portion of the petroleum-derived polyol components that have traditionally been used as polyol components for the production of polyurethane with biomass-derived components. Among these, lignin has attracted attention as a component for use in the production of polyurethane because of its relatively excellent flame retardancy and ability to improve mechanical strength (see, for example, Patent Documents 1 and 2).

[0003] JP 2013-170245 A JP 2017-537194 A

[0004] However, lignin generally has low solubility in polyol components, and is poorly soluble in polyols used in the production of rigid polyurethane molded articles, such as polypropylene glycol and polyester polyols. Therefore, when the lignin content of a rigid polyurethane resin is high, the insoluble components tend to be unevenly distributed in the rigid polyurethane resin, making it difficult to obtain a stable molded article. Therefore, it is necessary to limit the lignin content in the rigid polyurethane resin to a certain amount or less, and in most rigid polyurethane resins, only a small portion of the petroleum-derived polyol components can be substituted with lignin. Therefore, lignin does not necessarily contribute sufficiently to the stable production of rigid polyurethane resins.

[0005] An object of the present invention is to provide a curable composition in which a lignin component exhibits excellent solubility and which is suitable for producing polyurethane resins.

[0006] According to the present invention, the following curable compositions and the like are provided: 1. A curable composition comprising a lignin component containing two or more compounds represented by the following formula (1) and a polyol, wherein the content of the lignin component is 0.1 mass% or more and the total content of the compounds, based on the total amount of the lignin component, is 0.06 mass% or more. (In the formula, R ａis a hydrogen atom, a methyl group, an ethyl group, a furyl group, a hydroxymethylfuryl group, a hydroxyphenyl group, a hydroxymethoxyphenyl group, or a hydroxydimethoxyphenyl group. ｃ１ , R ｃ２ R each independently represents a hydroxyl group, an alkoxy group, an amino group, or a thiol group. １１ ~R ２０ R each independently represents a hydrogen atom, a hydroxyl group, a hydrocarbon group having 1 to 15 carbon atoms, a hydrocarbon ether group having 1 to 15 carbon atoms, or a group containing a carbonyl group. １１ ~R ２０ may be the same or different, provided that R １１ ~R １５ At least one of R is a hydrogen atom; １６ ~R ２０ At least one of the compounds represented by the following formula (1') is a hydrogen atom.) 2. A curable composition comprising a lignin component containing two or more compounds represented by the following formula (1') and a polyol, wherein the total content of the compounds is 0.03 mass% or more. (In the formula, R ａ is a hydrogen atom, a methyl group, an ethyl group, a furyl group, a hydroxymethylfuryl group, a hydroxyphenyl group, a hydroxymethoxyphenyl group, or a hydroxydimethoxyphenyl group. ｃ１ , R ｃ２ R each independently represents a hydroxyl group, an alkoxy group, an amino group, or a thiol group. １１ ~R ２０ R each independently represents a hydrogen atom, a hydroxyl group, a hydrocarbon group having 1 to 15 carbon atoms, a hydrocarbon ether group having 1 to 15 carbon atoms, or a group containing a carbonyl group. １１ ~R ２０ may be the same or different, provided that R １１ ~R １５ At least one of R is a hydrogen atom; １６ ~R ２０at least one of which is a hydrogen atom.) 3. A curable composition containing a lignin component and a polyol, wherein the lignin component has a differential distribution value (dw / dLogM) peak value of 50 or more and 150 or less at a molecular weight LogM of 2.4 to 2.6, as measured by gel permeation chromatography (GPC), or a difference in integrated distribution values ​​(%) at a molecular weight LogM of 2.4 to 2.55 of 5 or more and 15 or less. 4. The curable composition according to any one of 1 to 3, wherein the content of the lignin component is 1 to 900 parts by mass based on 100 parts by mass of the polyol. 5. The curable composition according to any one of 1 to 4, wherein the weight average molecular weight of the polyol is 200 to 8,000. 6. The curable composition according to any one of 1 to 5, wherein the polyol is one or more selected from the group consisting of aromatic polyols, alicyclic polyols, aliphatic polyols, polylactone polyols, polycarbonate polyols, polyester polyols, polyether polyols, and polymer polyols. 7. The curable composition according to any one of 1 to 6, wherein the polyol is one or more selected from the group consisting of polyethylene glycols, polypropylene glycols, and polyester polyols. 8. The curable composition according to any one of 1 to 7, wherein the weight average molecular weight (Mw) of the lignin component is 1,000 to 3,000. 9. The curable composition according to any one of 1 to 8, wherein the molecular weight distribution (Mw / Mn) of the lignin component is 2.2 to 3.5. 10. The curable composition according to any one of 1 to 9, wherein the content of the following compound (2) is 0.1 mass% or less: 11. The curable composition according to any one of 1 to 10, wherein the content of free phenol monomer is 0.02% by mass or more and 8.0% by mass or less. 12. A polyurethane resin composition comprising the curable composition according to any one of 1 to 11 and an isocyanate. 13. The polyurethane resin composition according to 12, wherein the polyurethane resin composition is a rigid polyurethane resin composition. 14. The polyurethane resin composition according to 12 or 13, comprising one or more additives selected from the group consisting of red phosphorus, phosphate esters, phosphate-containing flame retardants, bromine-containing flame retardants, and metal hydroxides. 15. A polyurethane molded article obtained by curing the polyurethane resin composition according to any one of 12 to 14.

[0007] According to the present invention, it is possible to provide a curable composition in which a lignin component exhibits excellent solubility and which is suitable for producing a polyurethane resin, and a polyurethane molded article using the same.

[0008] 1 is a photograph of the rigid polyurethane resin obtained in Example 12. FIG. 2 is a photograph of a polyurethane molded product molded from the rigid polyurethane resin shown in FIG.

[0009] Hereinafter, in this specification, "x to y" represents a numerical range of "x or more, y or less." When there are multiple lower limit values, such as "x or more," or multiple upper limit values, such as "y or less," for a single technical item, any combination of upper and lower limit values ​​may be selected from the upper and lower limit values.

[0010] [Curable Composition] A curable composition according to one embodiment of the present invention contains a lignin component containing two or more compounds represented by the following formula (1) and a polyol, wherein the content of the lignin component is 0.1% by mass or more, and the total content of the compounds, based on the total amount of the lignin component, is 0.06% by mass or more.

[0011]

[0012] (In the formula, R ａ is a hydrogen atom, a methyl group, an ethyl group, a furyl group, a hydroxymethylfuryl group, a hydroxyphenyl group, a hydroxymethoxyphenyl group, or a hydroxydimethoxyphenyl group. ｃ１, R ｃ２ R each independently represents a hydroxyl group, an alkoxy group, an amino group, or a thiol group. １１ ~R ２０ R each independently represents a hydrogen atom, a hydroxyl group, a hydrocarbon group having 1 to 15 carbon atoms, a hydrocarbon ether group having 1 to 15 carbon atoms, or a group containing a carbonyl group. １１ ~R ２０ may be the same or different, provided that R １１ ~R １５ At least one of R is a hydrogen atom; １６ ~R ２０ At least one of is a hydrogen atom.)

[0013] In formula (1), R ａ The lines extending from C to the left and right rings are R １１ ~R １５ and a carbon atom on the ring substituted with any of R １６ ~R ２０ and R is bonded to a carbon atom on the ring to which any of the above lines is attached. １１ ~R ２０ Two of the bonds are single bonds that connect to the respective lines.

[0014] The hydrocarbon group having 1 to 15 carbon atoms may be linear or branched, and these hydrocarbon groups may be saturated or unsaturated. The hydrocarbon group having 1 to 15 carbon atoms is preferably a linear or branched hydrocarbon group having 1 to 10 carbon atoms, more preferably a linear or branched hydrocarbon group having 1 to 5 carbon atoms, and even more preferably a linear hydrocarbon group having 1 to 3 carbon atoms. Any of these suitable hydrocarbon groups may be saturated or unsaturated.

[0015] The hydrocarbon ether group having 1 to 15 carbon atoms may be linear or branched, and these hydrocarbons may be saturated or unsaturated. The hydrocarbon ether group having 1 to 15 carbon atoms is preferably a linear or branched hydrocarbon ether group having 1 to 10 carbon atoms, more preferably a linear or branched hydrocarbon ether group having 1 to 5 carbon atoms, and even more preferably a linear hydrocarbon ether group having 1 to 3 carbon atoms. The hydrocarbons of these suitable hydrocarbon ether groups may be saturated or unsaturated.

[0016] The hydrocarbon ether group is, for example, —(CH ２ ) ａ -O-(CH ２ ) ｂ -H (where a and b are integers of 1 or more, provided that a+b is 2 or more). In this case, the hydrocarbon ether group being linear is represented by -(CH ２ ) ａ - and -(CH ２ ) ｂ The hydrocarbon ether group being branched means that any of the structures represented by -(CH ２ ) ａ - or -(CH ２ ) ｂ In addition, the hydrocarbon of the hydrocarbon ether group is saturated when the hydrocarbon is a -(CH ２ ) ａ - and -(CH ２ ) ｂ - indicates that the hydrocarbon of the hydrocarbon ether group is unsaturated, and -(CH ２ ) ａ - or -(CH ２ ) ｂ - indicates an unsaturated hydrocarbon. Also, the hydrocarbon ether group -(CH ２ ) ａ -O-(CH ２ ) ｂ When represented by -, the number of carbon atoms in the hydrocarbon ether group is the number represented by (a+b).

[0017] Examples of the group containing a carbonyl group include an aldehyde group (-CHO), a carboxyl group (-COOH), a carbonyl group (-COR), an ester group (-COOR), and an amide group (-CONRR').

[0018] R ｃ１ , R ｃ２ may be any of a hydroxyl group, an alkoxy group, an amino group, or a thiol group, but is preferably a hydroxyl group or an alkoxy group, and more preferably a hydroxyl group.

[0019] The curable composition of the present invention contains a lignin component containing two or more compounds represented by the above-described formula (1). In other words, the two or more compounds represented by formula (1) are present in the curable composition of the present invention as compounds contained in the lignin component. The lignin component can be obtained, for example, by extracting a lignin-containing material described below with a solvent containing an organic solvent and purifying the extracted material. Typically, the lignin component is a component containing the lignin described below as the main component (e.g., a lignin content of 90% by mass or more, 95% by mass or more, or 99% by mass or more). The lignin component and the extraction method thereof will be described in detail below.

[0020] The curable composition contains a lignin component containing two or more types of compounds represented by formula (1) (hereinafter, sometimes referred to as phenol dimers), and contains the lignin component in a predetermined amount or more. Furthermore, the total content of the phenol dimers based on the total amount of the lignin component is a predetermined amount or more, whereby the solubility of the lignin component in the polyol contained in the curable composition can be improved.

[0021] In the following description, "lignin component content" refers to the content of the lignin component in the entire curable composition, and typically refers to the content of a mixture of lignin, a phenol dimer, and a free phenol monomer, which will be described later, in the entire curable composition. Furthermore, in the following description, "total amount of lignin components" typically refers to the total amount of a mixture of lignin, a phenol dimer, and a compound (2), which will be described later, and a free phenol monomer, which will be described later.

[0022] The content of the lignin component relative to the entire curable composition is 0.1% by mass or more. By including a lignin component containing two or more types of phenol dimers within the above range, the solubility of the lignin component in polyols can be improved. Furthermore, when formed into a polyurethane resin, good mechanical properties and flame retardancy can be obtained. The content of the lignin component relative to the entire curable composition may be 1% by mass or more, 5% by mass or more, 10% by mass or more, 15% by mass or more, 20% by mass or more, 25% by mass or more, or 35% by mass or more. Furthermore, the content of the lignin component may be 80% by mass or less, 70% by mass or less, 65% by mass or less, 60% by mass or less, 55% by mass or less, or 45% by mass or less. This makes it possible to prevent an excessive increase in the proportion of components other than the phenol dimer contained in the lignin component, and the phenol dimer can effectively improve the solubility of the lignin component in the polyol.

[0023] The total content of the compounds represented by formula (1) based on the total amount of the lignin components is 0.06% by mass or more, optionally 0.1% by mass or more, 0.3% by mass or more, 0.5% by mass or more, or even 0.7% by mass or more. When the total content of the compounds represented by formula (1) is within the above range relative to the total amount of the lignin components, the solubility of the lignin components in polyols can be improved. The upper limit of the total content of the compounds represented by formula (1) based on the total amount of the lignin components is not particularly limited, but is typically 10% by mass or less.

[0024] The amount of lignin contained in the curable composition can be confirmed as a value calculated by measuring the amount of methoxyl groups contained in the curable composition in accordance with the method for measuring methoxyl groups by the Viebock and Schwappach method (see "Lignin Chemistry Research Methods," pp. 336-340, published by Uni Publishing in 1994), and substituting the measured value of the amount of methoxyl groups obtained as the amount of lignin.

[0025] The type and content of the phenol dimer represented by formula (1) contained in the curable composition are confirmed by liquid chromatography-mass spectrometry (LC / MS). Measurement by liquid chromatography-mass spectrometry (LC / MS) may be performed on either the curable composition or the lignin component. When the lignin component is measured by liquid chromatography-mass spectrometry (LC / MS), the content of the phenol dimer relative to the total lignin component can be calculated. Furthermore, when the lignin component is measured by liquid chromatography-mass spectrometry (LC / MS), the content of the phenol dimer relative to the total curable composition can be calculated depending on the mixing ratio of the polyol and other components mixed with the lignin component. In LC / MS, it is assumed that the curable composition contains the following compounds (a) to (h) as the compound represented by formula (1). For example, when the content of the target compound is less than 0.01% by mass, the target compound is considered to be below the detection limit. Measurement details are described in the Examples. The content of each of the compounds (a) to (h) identified by the above-mentioned LC / MS also includes the content of isomers that have the same molecular weight as each compound but different bonding positions.

[0026]

[0027] In this embodiment, for example, the curable composition contains two or more compounds selected from the above compounds (a) to (h).

[0028] The total content of the compound represented by formula (1) relative to the entire curable composition is preferably 0.001% by mass or more. This allows for improved solubility of the lignin component in the polyol. The total content may be 0.01% by mass or more, 0.03% by mass or more, 0.05% by mass or more, 0.1% by mass or more, 0.2% by mass or more, or 0.4% by mass or more. The total content may be 5% by mass or less, 3% by mass or less, 2% by mass or less, or 1% by mass or less. This allows for good mechanical properties and flame retardancy when formed into a polyurethane resin.

[0029] In one embodiment, the weight average molecular weight (Mw) of the curable composition is 200 to 8000. Mw may be 300 or more, or 500 or more. Furthermore, Mw may be 7000 or less, or 6000 or less. Note that the range of the weight average molecular weight (Mw) of the curable composition described above is an example, and the weight average molecular weight (Mw) of the curable composition is not necessarily limited to the above range.

[0030] In one embodiment, the content of the following compound (2) relative to the entire curable composition is 0.1% by mass or less, and may be 0.05% by mass or less.

[0031]

[0032] When the content of compound (2) is within the above range, loss of the solvent component due to reaction between the solvent components is suppressed in the lignin component extraction step described below, and it can be said that the lignin component is obtained by the solvent appropriately participating in lignin production in the lignin component extraction step. The content of compound (2) is measured by the method described in the Examples described below.

[0033] In one embodiment, the content of free phenol monomer relative to the entire curable composition is 0.02% by mass or more and 8.0% by mass or less. The free phenol monomer contained in the curable composition is mainly a portion of phenol used in the production of the lignin component that remains without being removed. The phenol content may be 0.1% by mass or more, 0.5% by mass or more, 1.0% by mass or more, 2.0% by mass or more, or 3.0% by mass or more. The phenol content is measured by the method described in the Examples below.

[0034] Another embodiment of the curable composition of the present invention contains a lignin component containing two or more compounds represented by the following formula (1') and a polyol, and the total content of the compounds is 0.03 mass% or more.

[0035]

[0036] (In the formula, R ａis a hydrogen atom, a methyl group, an ethyl group, a furyl group, a hydroxymethylfuryl group, a hydroxyphenyl group, a hydroxymethoxyphenyl group, or a hydroxydimethoxyphenyl group. ｃ１ , R ｃ２ R each independently represents a hydroxyl group, an alkoxy group, an amino group, or a thiol group. １１ ~R ２０ R each independently represents a hydrogen atom, a hydroxyl group, a hydrocarbon group having 1 to 15 carbon atoms, a hydrocarbon ether group having 1 to 15 carbon atoms, or a group containing a carbonyl group. １１ ~R ２０ may be the same or different, provided that R １１ ~R １５ At least one of R is a hydrogen atom; １６ ~R ２０ At least one of is a hydrogen atom.)

[0037] R of the compound represented by the above formula (1′) ａ , R ｃ１ , R ｃ２ , and R １１ ~R ２０ The explanation of R of the compound represented by the above formula (1) is as follows. ａ , R ｃ１ , R ｃ２ , and R １１ ~R ２０ This is similar to the explanation for

[0038] The curable composition of this embodiment contains a lignin component containing two or more compounds represented by the above-mentioned formula (1'). In other words, the two or more compounds represented by formula (1') are present in the curable composition of this embodiment as compounds contained in the lignin component. The lignin component contained in the curable composition is defined in the same way as described in the above-mentioned embodiment.

[0039] In this embodiment, the curable composition contains two or more compounds represented by formula (1') (hereinafter, sometimes referred to as phenol dimers) in a predetermined amount or more, thereby improving the solubility of the lignin component in the polyol contained in the curable composition.

[0040] The total content of the compound represented by formula (1') relative to the entire curable composition of this embodiment may be 0.001% by mass or more, 0.01% by mass or more, 0.03% by mass or more, 0.05% by mass or more, 0.1% by mass or more, 0.2% by mass or more, or 0.4% by mass or more. When the total content is within the above range, the solubility of the lignin component in the polyol can be improved. Furthermore, the total content may be 5% by mass or less, 3% by mass or less, 2% by mass or less, or 1% by mass or less. This allows for good mechanical properties and flame retardancy when formed into a polyurethane resin.

[0041] In this embodiment, the type and content of the phenol dimer represented by formula (1') contained in the curable composition can be confirmed by LC / MS in the same manner as the method for confirming the type and content of the phenol dimer represented by formula (1) contained in the curable composition of the above-mentioned embodiment. In LC / MS, it is assumed that the curable composition contains the above compounds (a) to (h) as the compound represented by formula (1').

[0042] In this embodiment, the preferred ranges of the weight-average molecular weight (Mw) of the curable composition, the preferred ranges of the content of the compound (2) relative to the entire curable composition, and the preferred ranges of the content of the free phenol monomer relative to the entire curable composition are the same as those described in the above-mentioned embodiment.

[0043] A curable composition according to another embodiment of the present invention contains a lignin component and a polyol, wherein the lignin component has a differential distribution value (dw / dLogM) peak maximum value of 50 to 150 at molecular weights LogM of 2.4 to 2.6, or a difference in integral distribution values ​​(%) at molecular weights LogM of 2.4 to 2.55, as measured by GPC. When the differential distribution value (dw / dLogM) peak maximum value of 50 to 150 at molecular weights LogM of 2.4 to 2.6, as measured by GPC, is 50 to 150, the solubility of the lignin component in the polyol can be improved. The maximum value may be 130 or less, or may be 110 or less. Similarly, when the difference in integral distribution values ​​(%) at molecular weights LogM of 2.4 to 2.55 is 5 to 15, the solubility of the lignin component in the polyol can be improved. The integral distribution value may be 7 or more, or may be 8 or more. It may also be 13 or less, or 12 or less.

[0044] As described above, the lignin component contained in the curable composition of the present invention can be obtained, for example, by extracting a lignin-containing material with a solvent containing an organic solvent and purifying the extracted material. The solvent containing an organic solvent typically contains at least a compound represented by the following formula (I):

[0045]

[0046] In the above formula (I), R ３１ ~R ３５ each independently represents a hydrogen atom, a hydroxyl group, a hydrocarbon group having 1 to 15 carbon atoms, a hydrocarbon ether group having 1 to 15 carbon atoms, or a group containing a carbonyl group; R ３１ ~R ３５ may be the same or different, provided that R ３１ ~R ３５ At least one of R is a hydrogen atom. ３１ ~R ３５ When R is a hydrocarbon group having 1 to 15 carbon atoms, the hydrocarbon group may be any of R １１ ~R ２０ It is the same as R ３１ ~R３５ When R is a hydrocarbon ether group having 1 to 15 carbon atoms, the hydrocarbon ether group is １１ ~R ２０ It is the same as R ３１ ~R ３５ is a group containing a carbonyl group, examples of the group containing a carbonyl group include R １１ ~R ２０ It is the same as R ｃ represents a hydroxyl group, an alkoxy group, an amino group, or a thiol group.

[0047] R ｃ may be any of a hydroxyl group, an alkoxy group, an amino group, or a thiol group, but is preferably a hydroxyl group or an alkoxy group, more preferably a hydroxyl group, in view of its affinity with the basic skeleton of lignin.

[0048] The solvent may contain a component other than the compound represented by formula (I). From the viewpoints of solubility of lignin in the raw material and economic efficiency, examples of the solvent component other than the compound represented by formula (I) include one or more of alcohols, ketones, ethers, esters, aromatic compounds other than the compound represented by formula (I), and water.

[0049] In this specification, "lignin" refers to a polymer compound formed by polymerizing three types of lignin monomers, which are p-hydroxycinnamic alcohols, and has a basic skeleton represented by the following formula (A).

[0050]

[0051] In the above formula (A), the substituent R ３ and R ４ represents a hydrogen atom or a methoxy group. ３ and R ４ When both of these are hydrogen atoms, the nucleus is p-hydroxyphenyl (H-type skeleton), and R ３ and R ４ When either one of the above is a hydrogen atom, the guaiacyl nucleus (G-type skeleton) is ３ and R ４and Y are not hydrogen atoms, the nucleus is called a syringyl nucleus (S-type skeleton). In the above formula (A), X indicates that it is bonded to a carbon atom, and Y indicates that it is bonded to a hydrogen atom or a carbon atom.

[0052] (Lignin-Containing Material) The lignin-containing material is not particularly limited as long as it is a material containing lignin. In one embodiment, the lignin-containing material is one or more selected from the group consisting of biomass and biomass residues. Examples of biomass residues include those derived from plant biomass such as woody biomass and herbaceous biomass. Examples of biomass residues include saccharification residues and fermentation residues of plant biomass (second-generation ethanol saccharification residues, second-generation ethanol fermentation residues, etc.), black liquor (sulfite lignin, kraft lignin, soda lignin, etc.), and any one or more of these can be used. Among these, from the viewpoints of ease of availability, the quality of the lignin component, and economic efficiency, it is preferable to use any one or more of saccharification residues and fermentation residues of plant biomass as the lignin-containing material.

[0053] Woody biomass and herbaceous biomass may be non-edible plant biomass or lignocellulosic biomass. Woody biomass includes, for example, conifers and broad-leaved trees such as cedar, cypress, Japanese cypress, cherry blossom, eucalyptus, beech, and bamboo. Herbaceous biomass includes, for example, palm trunks and empty bunches, palm fruit fiber and seeds, bagasse (sugarcane and high-biomass sugarcane pomace), cane tops (sugarcane tops and leaves), energy cane, rice straw, wheat straw, corn cobs, stems, and residues (corn stover, corn cobs, and corn hulls), sorghum (including sweet sorghum) residue, jatropha seed husks and shells, cashew husks, switchgrass, Erianthus, high-biomass yield crops, and energy crops. Among these, herbaceous biomass is preferred, and palm tree empty bunches, palm tree fruit fibers and seeds, wheat straw, corn cobs, stems, and residues (corn stover, corn cob, corn hull), bagasse, sorghum (including sweet sorghum) residue, cane tops, energy cane, and residues thereof after useful component extraction are more preferred. Palm tree empty bunches, corn cobs, stems, and residues (corn stover, corn cob, corn hull), bagasse, sorghum (including sweet sorghum) residue, cane tops, energy cane, and residues thereof after useful component extraction are even more preferred. The useful components include, for example, hemicellulose, carbohydrates, minerals, and moisture. Bagasse contains approximately 5 to 30% by mass of lignin. Furthermore, the lignin in bagasse contains all of the H-, G-, and S-nuclei as its basic skeleton. Crushed plant biomass can also be used. The material may be in any form such as a block, chip, powder, or a water-containing material.

[0054] Palm kernels, bagasse, corn stover, etc. are treated with organosolv, hot water under pressure, steam explosion, ammonia treatment, ammonia explosion, acid treatment, dilute sulfuric acid explosion, alkali treatment, oxidative decomposition, pyrolysis, microwave heating, or other methods, preferably acid treatment, dilute sulfuric acid explosion, or steam explosion, to separate hemicellulose into a solution, and then the cellulose is converted into glucose using an enzyme and separated into the solution. Alternatively, hemicellulose is saccharified together with cellulose without being separated and separated into the solution, with the remaining solid being the plant biomass saccharification residue. Alternatively, sugars are not separated, but are separated into ethanol by fermentation, with the remaining solid being the plant biomass fermentation residue. The plant biomass saccharification residue is primarily composed of lignin and contains decomposed organic matter, catalysts, enzymes, ash, cellulose, etc. Furthermore, the fermentation residue of plant biomass is mainly composed of lignin and also contains decomposed organic matter, catalysts, enzymes, yeast, ash, cellulose, etc.

[0055] A method for producing a lignin component is, for example, as follows: Using one or more of a saccharification residue and a fermentation residue of plant biomass as a raw material, a solvent containing, for example, a compound having one or more selected from the group consisting of a hydroxyl group and an ether bond (hereinafter also referred to as "organic solvent A") is added. Organic solvent A will be described in detail in the "Solvent" section below.

[0056] The solvent containing organic solvent A typically contains at least the compound represented by formula (I) above.

[0057] After adding the solvent, the mixture is heated for approximately 2 to 4 hours. Since the heated liquid contains insoluble matter, it is filtered using No. 2 filter paper. The filtered solids are unextracted components and inorganic impurities. The filtrate is distilled under reduced pressure to remove the solvent. Any solvent that remains after distillation is removed by vacuum drying. The separated solids are lignin components.

[0058] Furthermore, the lignin-containing material used as a raw material can be lignin separated from non-edible plant biomass by processes such as organosolv, hot water compression, steam explosion, ammonia treatment, ammonia explosion, acid treatment, dilute sulfuric acid explosion, alkali treatment, oxidative decomposition, pyrolysis, and microwave heating. Specifically, for example, the lignin contained in non-edible plant biomass can be dissolved into the solvent by treatment with an organic solvent or a solvent containing an organic solvent and water, and the lignin-containing solution can be filtered to remove cellulose and the like, and then concentrated and dried to obtain the separated lignin. Furthermore, lignin components can also be directly extracted from non-edible plant biomass by using a solvent containing organic solvent A as the organic solvent.

[0059] (Solvent) The solvent used for extraction contains an organic solvent. As described above, the solvent containing an organic solvent typically contains the compound represented by formula (I) above. Examples of organic solvents other than the compound represented by formula (I) above include alcohols such as methanol, ethanol, isopropyl alcohol, ethylene glycol, and polyethylene glycol; ketones such as acetone and methyl ethyl ketone; ethers such as tetrahydrofuran and 1,4-dioxane; esters such as ethyl acetate; and aromatics other than the compound represented by formula (I), such as toluene.

[0060] In one embodiment, a solvent containing organic solvent A (a compound having one or more selected from the group consisting of a hydroxyl group and an ether bond) is used to extract lignin. Using organic solvent A as the organic solvent for extracting lignin is expected to effectively prevent the lignin-derived extract from being hydrophilically modified. The extracted lignin component may have reacted with an organic solvent containing organic solvent A. Using organic solvent A makes it possible to effectively extract the lignin-derived extract.

[0061] When organic solvent A has hydroxyl groups, the number of hydroxyl groups that organic solvent A has is not particularly limited and may be, for example, 1 or more, and may be 10 or less, 5 or less, 4 or less, 3 or less, or 2 or less. The number of hydroxyl groups that organic solvent A has may be 1, 2, 3, 4, or 5, or may be 1, 2, or 3, or may be 1 or 2, or may be 1. Examples of organic solvent A having two hydroxyl groups include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, diethylene glycol, triethylene glycol, and polyethylene glycol. Examples of organic solvents A having three hydroxyl groups include glycerin, 1,2,3-butanetriol, 1,2,4-butanetriol, 1,2,3-heptatriol, 1,2,4-heptatriol, 1,2,5-heptatriol, and 2,3,4-heptatriol. Examples of organic solvents A having four hydroxyl groups include pentaerythritol and erythritol. Examples of organic solvents A having five hydroxyl groups include xylitol. Examples of organic solvents A having six hydroxyl groups include sorbitol.

[0062] From the viewpoints of improving lignin extraction efficiency and economic efficiency, the organic solvent A having two or more hydroxyl groups (organic solvent A having a plurality of hydroxyl groups) is preferably one or more selected from the group consisting of ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, and glycerin, more preferably one or more selected from the group consisting of ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, polyethylene glycol, polypropylene glycol, and glycerin, even more preferably one or more selected from the group consisting of ethylene glycol, polyethylene glycol, and glycerin, and even more preferably ethylene glycol and polyethylene glycol.

[0063] The organic solvent A is preferably a compound represented by the following formula (II): R—OH (II) (In formula (II), R is an alkyl group having 1 to 10 carbon atoms, or a substituted or unsubstituted phenyl group.)

[0064] When R is an alkyl group having 1 to 10 carbon atoms, the number of carbon atoms in the alkyl group may be 1 or more, 2 or more, 3 or more, or 4 or more, or may be 10 or less, 8 or less, or 6 or less. The alkyl group may be linear or branched. In particular, by making the number of carbon atoms in the alkyl group 2 or more, it is expected that the lignin-derived extract will be more significantly prevented from being modified to be hydrophilic. Furthermore, as the number of carbon atoms increases to 2 or more, 3 or more, or even 4 or more, it is expected that such an effect will be even more significantly exhibited. Examples of the compound represented by formula (II) in which R is an alkyl group having 1 to 10 carbon atoms include one or more selected from the group consisting of methanol, ethanol, 1-propyl alcohol, 2-propyl alcohol, 1-butyl alcohol, 2-butyl alcohol, isobutyl alcohol, tertiary butyl alcohol, 1-pentyl alcohol, 2-pentyl alcohol, 3-methyl-1-butyl alcohol, 1-hexyl alcohol, cyclohexyl alcohol, 1-heptyl alcohol, 1-octyl alcohol, and 2-ethylhexyl alcohol, and are preferably one or more selected from the group consisting of methanol, ethanol, 1-propyl alcohol, and 2-propyl alcohol, more preferably one or more selected from the group consisting of methanol, ethanol, and 2-propyl alcohol, and even more preferably ethanol.

[0065] The compound represented by the above formula (I) is a compound represented by the above formula (II), in which R is a substituted or unsubstituted phenyl group, and the hydroxyl group (the "OH" group in formula (II)) is the above-mentioned R ｃ The compound represented by the above formula (I) corresponds to the case where R ３１ , R ３３ and R ３５ It is preferable that at least one of R is a hydrogen atom. ３１ , R ３３ and R ３５ It is more preferable that all of are hydrogen atoms.

[0066] Examples of the compound represented by formula (I) include 2-alkylphenols such as phenol, catechol, resorcinol, hydroquinone, phloroglucinone, o-cresol, m-cresol, p-cresol, 2-ethylphenol, and 2-propylphenol; 3-alkylphenols such as 3-ethylphenol, 3-propylphenol, and cardanol; 4-alkylphenols such as 4-ethylphenol, 4-propylphenol, 4-octylphenol, and 4-nonylphenol; 5-alkylresorcinols such as 5-methylresorcinol, 5-ethylresorcinol, and 5-propylresorcinol; 3,5-dialkylphenols such as 3,5-dimethylphenol, 3-methyl-5-ethyl-phenol, and 3,5-diethylphenol; The alkyl ester is at least one selected from the group consisting of anisole, aniline, thiophenol, etc., preferably at least one selected from the group consisting of phenol, catechol, resorcinol, hydroquinone, o-cresol, m-cresol, p-cresol, cardanol, 4-octylphenol, 4-nonylphenol, and anisole, more preferably at least one selected from the group consisting of phenol, catechol, resorcinol, hydroquinone, o-cresol, m-cresol, p-cresol, and anisole, even more preferably at least one selected from the group consisting of phenol, o-cresol, m-cresol, p-cresol, and anisole, even more preferably at least one selected from the group consisting of phenol and anisole, and even more preferably phenol.

[0067] When a compound represented by formula (I), such as phenol, is used as the organic solvent, the lignin component is expected to react with the compound represented by formula (I), thereby increasing the number of H-type and G-type skeletons. When a compound represented by formula (I) is used as the organic solvent, the reaction between lignin and the compound represented by formula (I) increases the number of substituents R in the lignin basic skeleton represented by formula (A) in the lignin. ３ and R ４ However, it is expected that a substitution reaction occurs in which the structure is transformed into a structure derived from the compound represented by formula (I), and the compound represented by formula (1) is produced.

[0068] One or more types of organic solvents A may be used in combination. For example, one or more types selected from compounds represented by formula (II) in which R is an alkyl group having 1 to 10 carbon atoms may be used in combination with one or more types selected from compounds represented by formula (II) in which R is a substituted or unsubstituted phenyl group (i.e., compounds represented by formula (I)). As a specific example, ethanol and phenol may be used in combination.

[0069] The organic solvent may contain an organic solvent other than organic solvent A. The other organic solvent is not particularly limited, and examples thereof include ketones such as acetone and methyl ethyl ketone, esters such as ethyl acetate, and aromatics other than the compound represented by formula (I), such as toluene. One or more of the other organic solvents may be used in combination.

[0070] In one embodiment, 10% by weight or more, 20% by weight or more, 30% by weight or more, 40% by weight or more, 50% by weight or more, 60% by weight or more, 70% by weight or more, 80% by weight or more, 90% by weight or more, 95% by weight or more, 97% by weight or more, or 99% by weight or more of the organic solvent is organic solvent A.

[0071] The solvent used for extraction may contain water in addition to the organic solvent. The ratio of water to the organic solvent in the solvent used for extraction may be, for example, 10 parts by mass or more, 20 parts by mass or more, 30 parts by mass or more, 50 parts by mass or more, or 70 parts by mass or more, and may be 900 parts by mass or less, 700 parts by mass or less, 400 parts by mass or less, 300 parts by mass or less, or 100 parts by mass or less, per 100 parts by mass of the organic solvent.

[0072] When extracting lignin components from a lignin-containing material with a solvent, the solvent may or may not undergo phase separation. When the solvent undergoes phase separation, the "solvent used for extraction" refers to the solvent that constitutes the phase containing the lignin components at the highest concentration.

[0073] (Extraction) In the present invention, extraction refers to extracting a lignin component, including a lignin-derived extract, from a lignin-containing material containing components other than lignin. In one embodiment, "extraction" refers to extracting a lignin component from a lignin-containing solid when the lignin-containing material is a lignin-containing solid, and does not refer to adding an organic solvent to a solution in which all of the lignin has already been dissolved (e.g., an aqueous solution containing a basic compound). In such an embodiment, the lignin-containing material before extraction (the lignin-containing material before the addition of an organic solvent) contains either a lignin-containing solid and lignin already dissolved in a solvent, or a lignin-containing solid without lignin already dissolved in a solvent. The amount of solvent added to the lignin-containing material during extraction is not particularly limited. The mass ratio of solvent to lignin in the lignin-containing material [solvent / lignin] can be, for example, 0.1 or more, and can be 15 or less, 10 or less, 5 or less, 4 or less, 3 or less, 2 or less, 1 or less, 0.7 or less, or 0.5.

[0074] (Acid Catalyst) The above-described extraction can be carried out without a catalyst or in the presence of a catalyst. Examples of the catalyst include an acid catalyst. Examples of the acid catalyst include inorganic acids such as phosphoric acid, phosphate esters, hydrochloric acid, sulfuric acid, and sulfate esters, and organic acids such as acetic acid, formic acid, oxalic acid, and p-toluenesulfonic acid. One or more acid catalysts may be used in combination. The acid catalyst may be present in an amount of, for example, more than 0% by mass, 0.1% by mass or more, or 0.2% by mass or more, or 5.0% by mass or less, 3.0% by mass or less, or 2.6% by mass or less, based on 100 parts by mass of the total amount of lignin and solvent. When the extraction is carried out without a catalyst, for example, post-treatment (purification step) after the extraction step can be omitted.

[0075] The extraction temperature is not particularly limited as long as it allows extraction of lignin components from the lignin-containing material, and may be, for example, 100° C. or higher, 140° C. or higher, more than 140° C., 150° C. or higher, or 180° C. or higher, and may be 350° C. or lower, 300° C. or lower, 270° C. or lower, 250° C. or lower, or 230° C. or lower. Temperatures above 140° C. can improve the solubility of lignin (lignin components) and promote extraction, while temperatures below 300° C. can suitably prevent the progression of lignin recombination.

[0076] The extraction time can be set appropriately and may be, for example, 0.1 hours or more, 0.5 hours or more, 1 hour or more, or 2 hours or more, and may be 15 hours or less, 10 hours or less, or 8 hours or less.

[0077] (Purification) The lignin component is produced by the above-mentioned extraction, but may be purified after extraction, if necessary. An example of purification will be described below.

[0078] The extracted lignin components can be purified (purification process) by first subjecting them to a solid-liquid separation process. The extracted lignin components are dissolved in the solvent, while unextracted components and inorganic impurities remain in the liquid as solids. These are preferably removed by filtration (hot). For example, the extract is placed in a pressure (hot) filter equipped with filter paper such as No. 5C or No. 2, and pressure-filtered at approximately 20 to 100°C, approximately 20 to 70°C, typically approximately 20 to 50°C, and approximately 0.1 to 0.99 MPa, typically approximately 0.1 to 0.4 MPa. The filtered solid may be diluted and / or washed with an appropriate solvent and then filtered. During this filtration, the lignin components are contained in the filtrate. Alternatively, the extracted product may be diluted and / or washed with one or more low-boiling point common solvents, such as water, ketones (e.g., acetone, methyl ethyl ketone), alcohols (e.g., methanol, ethanol, isopropyl alcohol), and ethers (e.g., tetrahydrofuran), followed by solid-liquid separation. In the solid-liquid separation, the lignin component is contained in the solution. The method for performing the solid-liquid separation is not particularly limited, but examples thereof include filtration, a filter press, centrifugation, and a dehydrator.

[0079] The solution containing the lignin component may also be subjected to distillation. Distillation can be performed by removing the solvent by vacuum distillation at a temperature of about 40 to 200°C, usually about 50 to 150°C, under a reduced pressure of about 3 to 20 kPa, usually about 5 to 10 kPa. In this distillation, the lignin component is obtained as a solid or viscous solid. In addition, when using other dilution solvents, for example, the low-boiling point general-purpose solvent can be removed by vacuum distillation at an appropriate temperature taking into account the boiling point of the solvent, and then the solvent used for extraction can be removed in the same manner as above. In this distillation, the lignin component is obtained as a solid or viscous solid.

[0080] The lignin component obtained by distillation may be purified by heating it to typically 50 to 200°C and vacuum drying it in a solid or molten state to remove the remaining solvent (e.g., organic solvent A). Alternatively, the lignin component in a heated, fluid state after distillation may be similarly vacuum dried to remove the remaining solvent (e.g., organic solvent A) for purification.

[0081] The lignin component obtained by distillation or vacuum drying is preferably not reprecipitated. This allows for easy production of a lignin component containing the compound represented by formula (1) in the above-mentioned range. Furthermore, in the purification step, the filtration, distillation, and vacuum drying may be performed alone or in combination.

[0082] The amount of organic solvent remaining in the lignin component is not particularly limited, but is usually less than 30 mass%, preferably less than 10 mass%, more preferably less than 5 mass%, and even more preferably less than 1 mass%, of the total amount of these.

[0083] By the method for producing the lignin component contained in the curable composition of the present invention, of the lignin content contained in the saccharification residue of plant biomass or the fermentation residue of plant biomass, preferably 50 mass% or more is extracted as the lignin component, more preferably 60 mass% or more is extracted as the lignin component, even more preferably 70 mass% or more is extracted as the lignin component, even more preferably 80 mass% or more is extracted as the lignin component, and even more preferably 90 mass% or more is extracted as the lignin component.

[0084] In one embodiment, the weight average molecular weight (Mw) of the lignin component is 1,000 to 3,000. Mw may be 1,300 or more, or 1,500 or more. Furthermore, Mw may be 2,900 or less, or 2,700 or less.

[0085] In one embodiment, the molecular weight distribution (Mw / Mn) of the lignin component is 2.2 to 3.5. Mw / Mn may be 2.3 or more, 2.4 or more, 2.5 or more, or 2.6 or more. Mw / Mn may be 3.3 or less, 3.0 or less, or 2.7 or less. The molecular weights of the lignin component are measured by GPC using a method similar to that described in the Examples below.

[0086] In one embodiment, the polyol used is at least one selected from the group consisting of aromatic polyols, alicyclic polyols, aliphatic polyols, polylactone polyols, polycarbonate polyols, polyester polyols, polyether polyols, and polymer polyols.

[0087] Examples of aromatic polyols include bisphenol A, bisphenol F, phenol novolac, and cresol novolac.

[0088] Examples of alicyclic polyols include cyclohexanediol, methylcyclohexanediol, isophoronediol, cyclohexanedimethanol, dicyclohexylmethanediol, and dimethyldicyclohexylmethanediol.

[0089] The aliphatic polyol is, for example, an aliphatic polyol having 2 to 12 carbon atoms, and specific examples thereof include polybutadiene polyol, hydrogenated polybutadiene polyol, hydrogenated isoprene polyol, ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 1,10-decanediol, 1,12-dodecanediol, 2,2-diethylpropanediol, 2-ethyl-2-butylpropanediol, trimethylolethane, trimethylolpropane, and methylpentanediol. Ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 1,10-decanediol, and 1,12-dodecanediol are preferred, and ethylene glycol, 1,4-butanediol, neopentyl glycol, and 1,6-hexanediol are more preferred.

[0090] Examples of polylactone polyols include polycaprolactone polyols such as polypropiolactone glycol and polycaprolactone glycol, and polyvalerolactone glycol.

[0091] Examples of polyester polyols include adipate-based polyols such as ethylene glycol adipate, diethylene adipate glycol, butylene glycol adipate, and trimethylolpropane / diethylene glycol adipate, and aromatic polyester polyols. From the viewpoint of solubility of the lignin component, aromatic polyester polyols are preferred.

[0092] Examples of polycarbonate polyols include polyols obtained by dealcoholization reaction of a hydroxyl group-containing compound such as ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, octanediol, or nonanediol with diethylene carbonate or dipropylene carbonate.

[0093] Examples of polyether polyols include polytetramethylene ether glycol, polyethylene glycol, polypropylene glycol, and polytrimethylene ether glycol. Both polyethylene glycol and polypropylene glycol may be diol or triol. From the viewpoint of solubility of the lignin component, polyethylene glycol and polypropylene glycol are preferred, and triol polypropylene glycol is more preferred.

[0094] Examples of polymer polyols include polymers obtained by graft polymerizing the above-mentioned aromatic polyols, alicyclic polyols, aliphatic polyols, polyester polyols, etc. with ethylenically unsaturated compounds such as acrylonitrile, styrene, methyl acrylate, and methacrylate; polybutadiene polyols; modified polyols of polyhydric alcohols; and hydrogenated products thereof.

[0095] These polyols may be used alone or in combination of two or more.

[0096] Among the above-mentioned polyols, at least one selected from the group consisting of polyethylene glycol, polypropylene glycol, and polyester polyols is preferred from the viewpoint of solubility of the lignin component and ease of handling. Among these, triol-type polypropylene glycol or aromatic polyester polyol is more preferred.

[0097] In one embodiment, the weight average molecular weight (Mw) of the polyol is 200 to 8000. This allows the polyol to exhibit good reactivity with the isocyanate described below and to dissolve the lignin component well. Mw may be 250 or more, or 300 or more. Furthermore, Mw may be 8000 or less, 7000 or less, or less than 7000.

[0098] In one embodiment, the polyol content relative to the entire curable composition is 20 to 99% by mass. This allows the lignin component to dissolve well. The polyol content may be 30% by mass or more, 40% by mass or more, or 60% by mass or more. Furthermore, the polyol content may be 95% by mass or less, 90% by mass or less, or 80% by mass or less.

[0099] In one embodiment, the content of the lignin component is 1 to 900 parts by mass based on 100 parts by mass of the polyol. This ensures that the content ratio of the lignin component to the polyol is within an appropriate range, thereby enabling the lignin component to exhibit good solubility in the polyol and achieving good mechanical strength when the curable composition of the present invention is used as a polyurethane resin. The content of the lignin component may be 1 part by mass or more, 10 parts by mass or more, or even 30 parts by mass or more based on 100 parts by mass of the polyol. Furthermore, the content of the lignin component may be 500 parts by mass or less, 300 parts by mass or less, or 100 parts by mass or less based on 100 parts by mass of the polyol.

[0100] From the viewpoint of ease of handling, the viscosity of the curable composition at 55°C measured in accordance with JIS K7117-1 may be 50 to 20,000 mPa s, 400 to 13,000 mPa s, or 800 to 9,000 mPa s. The viscosity of the curable composition is measured by the method described in the examples below.

[0101] The curable composition according to one embodiment may comprise, for example, 70% by mass or more, 80% by mass or more, 90% by mass or more, 98% by mass or more, 99% by mass or more, 99.5% by mass or more, 99.9% by mass or more, or 100% by mass of the curable composition.

[0102] [Polyurethane Resin Composition] A polyurethane resin composition according to one embodiment of the present invention comprises the curable composition of the present invention described above and an isocyanate. The polyurethane resin composition according to the present invention is a composition containing raw materials that are polymerized to form a polyurethane resin as essential components, and is a composition that does not contain a polyurethane resin or contains a polyurethane resin as an optional component.

[0103] The isocyanate is not particularly limited as long as it is a polyisocyanate having two or more isocyanate groups per molecule. Examples of the isocyanate include aliphatic isocyanates, alicyclic isocyanates, aromatic isocyanates, and modified versions thereof. Examples of the aliphatic isocyanates include hexamethylene diisocyanate, lysine diisocyanate, lysine triisocyanate, dimer acid diisocyanate, norbornene diisocyanate, octadecyl isocyanate, methyl isocyanate, and butyl isocyanate. Examples of the alicyclic isocyanates include isophorone diisocyanate, hydrogenated phenylmethane diisocyanate, trimethylhexamethylene diisocyanate, and hydrogenated xylylene diisocyanate. Examples of aromatic isocyanates include tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, polymeric diphenylmethane diisocyanate, triphenylmethane triisocyanate, tris(isocyanatophenyl)thiophosphate, phenyl isocyanate, paraphenylene diisocyanate, and tetramethylxylene diisocyanate. Examples of modified isocyanates include urethane prepolymer, hexamethylene diisocyanate biuret, hexamethylene diisocyanate trimer, and isophorone diisocyanate trimer. Other examples include plant-derived isocyanates such as castor oil. These isocyanates can be used alone or in combination.

[0104] The NCO index of the polyurethane resin composition is preferably 0.7 to 2.0, more preferably 0.8 to 1.8, and particularly preferably 0.9 to 1.7. An NCO index of 0.7 or more results in a good polyurethane resin. An NCO index of 2.0 or less suppresses an increase in compression set. In this specification, the NCO index represents the ratio (NCO / OH) of the isocyanate group (NCO) in the isocyanate to the total amount of hydroxyl groups (OH) contained in the entire polyol, including the lignin component and other polyol components.

[0105] In one embodiment, the polyurethane resin composition may further contain a catalyst. For example, a tertiary amine may be used as a urethanization catalyst. Furthermore, a metal salt and / or a quaternary ammonium salt may be used as a trimerization reaction-accelerating catalyst. The urethanization catalyst and the trimerization reaction-accelerating catalyst may be used in combination. For example, a tertiary amine may be used in combination with a metal salt and / or a quaternary ammonium salt.

[0106] Tertiary amines include N,N,N',N'-tetramethylethylenediamine, N,N,N',N'-tetramethylpropylenediamine, N,N,N',N",N"-pentamethyldiethylenetriamine, N,N,N',N",N"-pentamethyl-(3-aminopropyl)ethylenediamine, N,N,N',N",N"-pentamethyldipropylenetriamine, N,N,N',N'-tetramethylguanidine, 1,3,5-tris(N,N-dimethylamino-propyl)hexahydro-s-triazine, 1,8-diazabicyclo[4.1.2.1] Examples of the methylaminoethyl amine include [5.4.0]undecene-7, triethylenediamine, N,N,N',N'-tetramethylhexamethylenediamine, N,N'-dimethylpiperazine, dimethylcyclohexylamine, N-methylmorpholine, N-ethylmorpholine, bis(2-dimethylaminoethyl)ether, 1-methylimidazole, 1,2-dimethylimidazole, 1-isobutyl-2-methylimidazole, 1-dimethylaminopropylimidazole, and N-methyl-N-(N,N-dimethylaminoethyl)ethyl alcoholamine.

[0107] Examples of metal salts include potassium salts, tin salts, and lead salts, such as potassium acetate, potassium 2-ethylhexanoate, dibutyltin dilaurate, tin octoate, lead octoate, and bismuth 2-ethylhexanoate.

[0108] Examples of quaternary ammonium salts include tetraalkylammonium halides such as tetramethylammonium chloride; tetraalkylammonium hydroxides such as tetramethylammonium hydroxide; tetraalkylammonium organic acid salts such as tetramethylammonium 2-ethylhexanoate, 2-hydroxypropyltrimethylammonium formate, and 2-hydroxypropyltrimethylammonium 2-ethylhexanoate; and quaternary ammonium compounds obtained by reacting a quaternary ammonium carbonate, which is obtained by reacting a tertiary amine such as N,N,N',N'-tetramethylethylenediamine with a carbonate diester, with 2-ethylhexane through an anion exchange reaction.

[0109] The content of the catalyst is preferably 0.1 to 5 parts by mass relative to 100 parts by mass of the mixture of the lignin component and the polyol. By adjusting the content of the catalyst, the reactivity of the mixture of the lignin component and the polyol with the isocyanate can be controlled.

[0110] In one embodiment, the polyurethane resin composition may further contain a blowing agent. Examples of the blowing agent include HCFC-based blowing agents such as HCFC-141b, HCFC-142b, HCFC-124, and HCFC-22; HFC-based blowing agents such as 1,1,1,2-tetrafluoroethane (HFC-134a), 1,1,1,3,3-pentafluoropropane (HFC-245fa), 1,1,1,3,3-pentafluorobutane (HFC-365mfc), 1,1,2,2-tetrafluoroethyl difluoromethyl ether (HFE-236pc), 1,1,2,2-tetrafluoroethyl methyl ether (HFE-254pc), and 1,1,1,2,2,3,3-heptafluoropropyl methyl ether (HFE-347mcc); and HFC-based blowing agents such as those manufactured by Mitsui Chemours. Examples of blowing agents include hydrofluoroolefins such as Opteon 1100 manufactured by Fluoro Products Co., Ltd.; hydrocarbon blowing agents such as butane, hexane, cyclohexane, n-pentane, iso-pentane, and cyclopentane; water; and inert gases such as air, nitrogen, and carbon dioxide. The inert gas may be added in any of a liquid state, a supercritical state, and a subcritical state. When a blowing agent other than water is used, one type may be used alone, or two or more types may be used in combination.

[0111] When water is used as a blowing agent or blowing aid, the content of water is preferably 0.5 to 10 parts by mass, more preferably 0.5 to 7 parts by mass, relative to 100 parts by mass of the mixture of the lignin component and the polyol. When pentane (one or more selected from the group consisting of normal pentane, isopentane, and cyclopentane) is used as the blowing agent, the content of pentane is preferably 0.5 to 60 parts by mass, more preferably 0.5 to 50 parts by mass, relative to 100 parts by mass of the mixture of the lignin component and the polyol. When a hydrofluoroolefin is used as the blowing agent, the content of the hydrofluoroolefin is preferably 5 to 50 parts by mass, more preferably 10 to 30 parts by mass, relative to 100 parts by mass of the mixture of the lignin component and the polyol.

[0112] In one embodiment, the polyurethane resin composition may further contain a foam stabilizer (surfactant). Examples of the foam stabilizer (surfactant) include a silicone-based foam stabilizer and a fluorine-containing compound-based foam stabilizer.

[0113] Examples of silicone-based foam stabilizers include compounds containing a block copolymer of dimethylpolysiloxane and polyether. Specific examples include SZ-1671, SZ-1718, SH-193, SZ-1642, and SF Series No. 193 manufactured by Dow Corning Toray Co., Ltd., L-6884, L-5440, and L-5420 manufactured by Momentive Corporation, and B8443, B8490, and B8460 manufactured by Evonik.

[0114] The content of the foam stabilizer is preferably 0.1 to 10 parts by mass, more preferably 0.3 to 5 parts by mass, based on 100 parts by mass of the mixture of the lignin component and the polyol.

[0115] In one embodiment, the polyurethane resin composition may further contain a flame retardant. Examples of the flame retardant include red phosphorus, phosphate esters, phosphate-containing flame retardants, bromine-containing flame retardants, and metal hydroxides. Examples of the phosphate ester include triethyl phosphate, tributyl phosphate, trischloroethyl phosphate, trischloropropyl phosphate (abbreviated as TCPP), triphenyl phosphate, tricresyl phosphate, and polyphosphoric acid.

[0116] The content of the flame retardant is preferably 10 to 60 parts by mass, more preferably 20 to 40 parts by mass, per 100 parts by mass of the mixture of the lignin component and the polyol, from the viewpoint of obtaining excellent mechanical strength and flame retardancy when formed into a polyurethane resin.

[0117] Other additives that can be added besides those mentioned above include fillers such as calcium carbonate and barium sulfate, anti-aging agents such as antioxidants and ultraviolet absorbers, plasticizers, colorants, anti-mold agents, anti-foaming agents, dispersants, anti-discoloration agents, etc. These may be used alone or in combination of two or more.

[0118] The polyurethane resin composition may be a flexible polyurethane resin composition or a rigid polyurethane resin composition, but the curable composition according to one embodiment of the present invention is more suitable for producing a rigid polyurethane resin composition.

[0119] [Polyurethane Resin] A polyurethane resin according to one embodiment of the present invention is obtained by curing the polyurethane resin composition according to the present invention described above. The polyurethane resin may be a flexible polyurethane resin or a rigid polyurethane resin, but the polyurethane resin composition according to one embodiment of the present invention is more suitable for producing a rigid polyurethane resin.

[0120] The method for producing a polyurethane resin of the present invention includes a step of reacting a lignin component, a polyol, and an isocyanate contained in the polyurethane resin composition of the present invention in the presence of a foam stabilizer, a catalyst, and a blowing agent.

[0121] In one embodiment, the polyurethane resin can be produced by mixing the lignin component and the polyol for 0.1 to 3 hours at room temperature or at a temperature of 50°C to 150°C, and then mixing an isocyanate, a catalyst component, a flame retardant, a blowing agent, etc.

[0122] In one embodiment, the density of the polyurethane resin is, for example, 25.0 kg / m ３ or more, and 70 kg / m ３ It may be the following:

[0123] In one embodiment, the compressive strength of the polyurethane resin may be 50 kPa or more and 500 kPa or less. The compressive strength is measured by the method described in the examples below.

[0124] [Molded Article] A polyurethane molded article according to one embodiment of the present invention is obtained by molding the polyurethane resin of the present invention described above.

[0125] The polyurethane molded article of the present invention can be used for automobile parts, machine parts, industrial parts, home appliance parts, bedding and furniture, electric wires, cables, rolls, hoses, tubes, belts, films, sheets, laminated articles, coatings, adhesives, sealants, sporting goods, leisure goods, shoe-related parts, miscellaneous goods, nursing supplies, housing supplies, medical supplies, building materials, civil engineering-related products, heat insulating materials, waterproofing materials, packaging materials, heat-insulating materials, cold-insulating materials, slurry powders, vibration absorbing materials, etc. Furthermore, an appropriate surface material can be provided on one or both sides of the polyurethane molded article of the present invention. Examples of the surface material include paper, wood, gypsum board, resin, aluminum foil, and steel plate.

[0126] [Preparation of Lignin Component] Production Example 1 (1) Extraction Step 100 parts by mass of saccharification residue of non-edible plant biomass (lignin content: 68% by mass) (68 parts by mass as lignin), 245 parts by mass of phenol, and 27 parts by mass of water were placed in a stirrable pressure-resistant container and heated and stirred at 1.7 MPa and 220°C for 2 hours.

[0127] (2) Purification Step (2-1) Filtration After dilution with acetone, the extract obtained in the above extraction step was placed in a pressure filter equipped with No. 2 filter paper, pressurized to 0.1 to 0.4 MPa with compressed air or nitrogen, and filtered.

[0128] (2-2) Distillation The filtrate obtained in (2-1) above was distilled under reduced pressure (5 to 10 kPa) and heated (40 to 60°C) using an evaporator to remove acetone. Also, phenol was distilled under reduced pressure (100 to 140°C) using an evaporator to remove phenol.

[0129] (2-3) Drying under reduced pressure In order to remove the phenol remaining in (2-2) above, the mixture was vacuum dried under reduced pressure (1.0 to 5.0 kPa) and heating (120 to 150°C) to remove the phenol, thereby obtaining a lignin component (1).

[0130] [Analysis of Lignin Components] The lignin component (1) obtained in Production Example 1 and the lignin component (2) shown below were evaluated for the following items (1) to (3). Lignin component (2): Kraft lignin (Lignin, alkali (product number 370959) manufactured by SIGMA-ALDRICH)

[0131] (1) Phenol Content The phenol content was measured using high-performance liquid chromatography (HPLC). Specifically, 50 mg of each sample of lignin components (1) to (2) was dissolved in 0.5 mL of tetrahydrofuran, and 4.5 mL of a 4:1 (volume ratio) water / acetonitrile mixed solvent was added. The mixture was stirred for 30 minutes, and the supernatant was filtered to prepare a measurement sample. 1 μL of the measurement sample was injected into an "ACQUITY UPLC H-CLASS" connected to a BEH C18 (1.7 μm × 2.1 mm × 50 mm) column. The column temperature was set to 40 °C, and a mixed solvent of 2 mM ammonium acetate aqueous solution (A) and acetonitrile (B) was used as the mobile phase. A gradient method was used in which the flow rate ratio (A:B) was gradually changed from 80:20 to 10:90. Measurements were performed using an ultraviolet-visible (UV) detector at 280 nm. The phenol content in the sample was calculated from a calibration curve of a standard phenol solution prepared separately.

[0132] (2) Dimer component (compound represented by formula (1) and compound (2)) The content of the dimer component (phenol dimer and compound (2)) was measured using liquid chromatography-mass spectrometry (LC / MS). Specifically, 50 mg of each sample of lignin components (1) to (2) was dissolved in 0.5 mL of tetrahydrofuran, and 4.5 mL of a 4 / 1 (volume ratio) water / acetonitrile mixed solvent was added. The mixture was stirred for 30 minutes, and the supernatant was filtered to prepare a measurement sample. 1 μL of the measurement sample was injected into an LC-MS system equipped with an "ACQUITY UPLC H-CLASS" separation column connected to a BEH C18 (1.7 μm × 2.1 mm × 50 mm) column and a "Xevo G2-XS QTof" detection column. The column temperature was set to 40°C, and a mixed solvent of 2 mM ammonium acetate aqueous solution (A) and acetonitrile (B) was used as the mobile phase. The dimer components were separated using a gradient method in which the flow rate ratio (A:B) was gradually changed from 80:20 to 10:90. The resulting dimer components were ionized by electrospray ionization and then measured in the mass-to-charge ratio range of 50 to 1000 using a negative-mode quadrupole time-of-flight mass spectrometer. Assuming that all compounds were detected in their deprotonated form, the structures of the dimer components contained in the sample were determined from the mass-to-charge ratios to be compounds (a) to (h) and compound (2) below. Chromatograms were extracted at the mass-to-charge ratios corresponding to the structure of each compound, and the peak areas were calculated. The content of the phenol dimer component in the sample was calculated from a calibration curve of a separately prepared standard 2,2'-dihydroxydiphenylmethane solution.

[0133]

[0134] The evaluation results of (1) and (2) above are shown in Table 1.

[0135]

[0136] The "lignin" content shown in Table 1 is a value (lignin content based on the total amount of lignin components) calculated assuming that all components contained in lignin components (1) and (2) other than phenol dimers (compounds (a) to (h)), compound (2), and free phenol monomers are lignin. That is, in the following description, "total amount of lignin components" refers to the total amount of phenol dimers (compounds (a) to (h)), compound (2), free phenol monomers, and lignin. Furthermore, "total amount of compounds (a) to (h)" in Table 1 indicates the content ratio of the total amount of compounds represented by formula (1) or (1') to the total amount of lignin components (total content of compounds represented by formula (1) or (1') based on the total amount of lignin components).

[0137] (3) GPC measurement of lignin components The number average molecular weight Mn, weight average molecular weight Mw, Z-average molecular weight Mz, and molecular weight distribution (Mw / Mn) were measured by gel permeation chromatography (GPC). Specifically, the measurement samples were prepared by dissolving the lignin components (1) and (2) in tetrahydrofuran. Two general-purpose organic columns packed with styrene-based polymer fillers, "TSKgel GMHXL (manufactured by Tosoh Corporation)" and "G2000HXL (manufactured by Tosoh Corporation)," were connected in series to a GPC system "HLC-8220GPC (manufactured by Tosoh Corporation)" or "HLC-8420GPC (manufactured by Tosoh Corporation)." 100 μL of the measurement sample was injected into the GPC system, and the eluent tetrahydrofuran was developed at 40 ° C. at 1.0 mL / min, and the retention time was measured using the differential refractive index (RI). The average molecular weight of each sample was calculated from a calibration curve showing the relationship between the retention time and molecular weight of a separately prepared standard polystyrene. In addition, since some insoluble components were generated in tetrahydrofuran from kraft lignin (lignin component (2)), only the soluble components were analyzed.

[0138] The following items (a) to (d) were calculated from the molecular weight chart of the sample determined by GPC. (a) Molecular weight Log M of the peak maximum value at molecular weight Log M of 2.4 to 2.6 (molecular weight Log M 2.4-2.6 peak) In the molecular weight chart of the sample determined by GPC (plotted with dw / dLog M on the y-axis and Log M on the x-axis), the molecular weight Log M value showing the peak maximum value of the differential distribution value (dw / dLog M) at molecular weight Log M of 2.4 to 2.6 was designated as the "molecular weight Log M 2.4-2.6 peak." (b) Maximum differential distribution value (dw / dLogM) In a chart of the molecular weight of a sample obtained by GPC (plotted with dw / dLogM on the y-axis and LogM on the x-axis), the maximum value of the peak of the differential distribution value (dw / dLogM) present at molecular weights LogM of 2.4 to 2.6 was taken as the "maximum differential distribution value (dw / dLogM)". (c) Molecular weight LogM2.4 integral distribution value (%), molecular weight LogM2.55 integral distribution value (%) In a chart of the molecular weight of a sample obtained by GPC (plotted with integral distribution value (%) on the y-axis and LogM on the x-axis), the integral distribution value (%) at molecular weight LogM2.4 and the integral distribution value (%) at molecular weight LogM2.55 were taken as the "molecular weight LogM2.4 integral distribution value" and the "molecular weight LogM2.55 integral distribution value", respectively. (d) Integral distribution value (%) 2.55-2.4 The difference obtained by subtracting the integral distribution value (%) of molecular weight Log M2.4 from the integral distribution value (%) of molecular weight Log M2.55 was taken as the "integral distribution value (%) 2.55-2.4." The evaluation results are shown in Table 2.

[0139]

[0140] [Curable Composition] Examples 1 to 11, Comparative Examples 1 to 8 (1) Preparation of Curable Composition The lignin components (1) and (2) described above and a polyol were mixed in the proportions shown in Tables 3 and 4, respectively. The resulting mixture was heated to 130°C using a hot stirrer and then stirred and mixed for 3 hours while maintaining the temperature at 130°C to obtain a curable composition. The values ​​in Tables 3 and 4 indicate the weight percentage (mass%) of each component in the overall curable composition. Note that "phenol dimer" in Tables 3 and 4 indicates the weight percentage (mass%) of the total amount of compounds (a) to (h) (compounds represented by formula (1) or formula (1')) contained in any of the lignin components (1) and (2) in the overall curable composition (total content of compounds represented by formula (1) or formula (1')).

[0141]

[0142]

[0143] In Tables 3 and 4, the abbreviations in the polyol column indicate the following product names: PPG400: "Polypropylene glycol 400" (manufactured by Junsei Chemical Co., Ltd.), weight-average molecular weight: 400 PPG700: "Polypropylene glycol 700" (manufactured by Junsei Chemical Co., Ltd.), weight-average molecular weight: 700 PPG300 triol: "Polypropylene glycol 300 (triol type)" (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), weight-average molecular weight: 300 PPG700 triol: "Polypropylene glycol 700 (triol type)" (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), weight-average molecular weight: 700 Maximol: Aromatic polyester polyol "MAXIMOL (registered trademark)" (manufactured by Kawasaki Kasei Chemical Industries, Ltd.)

[0144] (2) Solubility Evaluation of Curable Compositions The curable compositions of Examples 1 to 11 and Comparative Examples 1 to 8 were subjected to the following solubility evaluations (1) and (2). Solubility evaluation (1): Each curable composition was placed in a transparent container, and the state of the inner wall surface of the container and the state of the curable composition were visually confirmed to evaluate the state of dissolution of the lignin component in the polyol. Solubility evaluation (2): Each curable composition was applied to a slide glass, and the state of the coating liquid was visually confirmed to evaluate the state of dissolution of the lignin component in the polyol.

[0145] In the solubility evaluations (1) and (2), the solubility was evaluated according to the following criteria. The evaluation results are shown in Tables 3 and 4. (Solubility Evaluation (1)) A: Well dissolved, with no residual material remaining on the inner wall of the container. B: Almost completely dissolved, with some residual material remaining on the inner wall of the container. C: Almost completely dissolved, with either the lignin component and polyol separating into two layers or the solid lignin component remaining in the curable composition. (Solubility Evaluation (2)) A: Well dissolved, with no turbidity observed in the coating liquid. B: Almost completely dissolved, with some turbidity observed in the coating liquid. C: Almost completely dissolved, with either the coating liquid being clearly turbid, the solid lignin component remaining in the coating liquid, or the lignin component and polyol separating into two layers in the coating liquid. (Overall Evaluation) The solubility was evaluated comprehensively based on the results of the solubility evaluations (1) and (2). AA: The best evaluation was obtained in both solubility evaluations (1) and (2). A: A slightly inferior result was obtained in either solubility evaluation (1) or (2), but it was confirmed that there were no problems with solubility. B: A slightly inferior result was obtained in both solubility evaluations (1) and (2), but it was confirmed that there were no problems with solubility in general. C: A poor result was obtained in both solubility evaluations (1) and (2), and it was confirmed that the lignin component was not dissolved.

[0146] In Examples 1 to 11, it was confirmed that the lignin component was well dissolved in the polyol. On the other hand, in Comparative Examples 1 and 3, it was confirmed that the lignin component and the polyol were separated into two layers in solubility evaluation (1), and it was confirmed that the coating solution was clearly cloudy in solubility evaluation (2). Furthermore, in Comparative Examples 2, 4, and 6, it was confirmed that the lignin component remained in a solid state in both solubility evaluations (1) and (2). Furthermore, in Comparative Examples 7 and 8, it was confirmed that the lignin component and the polyol were separated into two layers in both solubility evaluations (1) and (2).

[0147] (3) Viscosity of Curable Composition The viscosity of the curable compositions of Examples 1 to 11 and Comparative Examples 1 to 8 was measured by the method described below. The measurement results are shown in Tables 3 and 4. Note that blank spaces in the viscosity column in Tables 3 and 4 indicate that viscosity measurement was not performed.

[0148] Viscosity measurements were performed in accordance with JIS K7117-1 for type B viscosity measurement. First, the lignin component and polyol were mixed, and the resulting mixture was heated at 100 ° C for 30 minutes and stirred to prepare a mixture for viscosity measurement. Next, the mixture was left to stand in a 55 ° C water bath for 30 minutes, and after the temperature of the mixture for viscosity measurement had stabilized at the measurement temperature, viscosity measurement was started. Viscosity measurements were performed using a "TVB22LT (manufactured by Toki Sangyo Co., Ltd.)" measuring device and an L adapter (for low viscosity) rotor at a rotation speed of 0.3 rpm and a measurement temperature of 55 ° C.

[0149] [Polyurethane Resin Composition and Molded Article] (1) Preparation of Polyurethane Resin Composition and Production of Rigid Polyurethane Resin Example 12 100 parts by mass of the curable composition obtained in Example 11 and the components shown in Table 5 (catalyst, flame retardant, foam stabilizer, foaming aid, and blowing agent) were mixed at room temperature in the proportions shown in Table 5, and then isocyanate was mixed in the proportions shown in Table 5 to obtain a polyurethane resin composition. The obtained polyurethane resin composition was foamed in a container and then heated in an oven at 50°C overnight to obtain a rigid polyurethane resin. A photograph of the appearance of the obtained rigid polyurethane resin is shown in Figure 1.

[0150] Comparative Example 9 A polyurethane resin composition was obtained by mixing 100 parts by mass of a curable composition obtained by mixing only the polyol component in the ratio shown in Table 5 without blending the lignin component and the components shown in Table 5 (catalyst, flame retardant, foam stabilizer, foaming aid, and foaming agent) at room temperature in the ratio shown in Table 5, and then mixing isocyanate in the ratio shown in Table 5. Thereafter, a rigid polyurethane resin was obtained in the same manner as in Example 12.

[0151] (2) Production of polyurethane molded article Each of the rigid polyurethane resins obtained in Example 12 and Comparative Example 9 was released from the container and cut out to obtain a polyurethane molded article. A photograph of the appearance of the polyurethane molded article obtained in Example 12 is shown in Figure 2.

[0152]

[0153] The product names of the products used as each component of the polyurethane resin composition shown in Table 5 are shown below. Tertiary amine (catalyst): "TOYOCAT-RX5" (manufactured by Tosoh Corporation) Trichlorophosphate (flame retardant): "TMCPP", trischloropropyl phosphate (manufactured by Daihachi Chemical Industry Co., Ltd.) Silicone surfactant (foam stabilizer): "SF Series No. 193" (manufactured by Dow-Toray Industries, Inc.) Hydrofluoroolefin (blowing agent): "Opteon 1100" (manufactured by Mitsui-Chemours Fluoroproducts Co., Ltd.) Polymeric MDI (isocyanate): "Millionate MR-200", polymeric diphenylmethane diisocyanate (MDI) (manufactured by Tosoh Corporation)

[0154] (3) Density of Rigid Polyurethane Resin Each of the rigid polyurethane resins obtained in Example 12 and Comparative Example 9 was cut to cut out cubic test pieces (blocks) with sides of 50 mm, and the density was calculated from the measured dimensions and mass of each test piece (block). The results are shown in Table 5. In both Example 9 and Comparative Example 12, the density was 35 kg / m ３ A rigid polyurethane resin having a density of 1000 or more was obtained. Therefore, it was confirmed that the density was sufficient for both the compressive strength test and the flammability test.

[0155] (4) Compressive Strength of Rigid Polyurethane Resin This was carried out in accordance with JIS K7222. First, each of the rigid polyurethane resins obtained in Example 12 and Comparative Example 9 was machined to cut out cubic test pieces (blocks) with sides of 50 mm. The compressive strength of each of the obtained test pieces (blocks) was measured using a universal testing machine, Model 59R5582 (manufactured by Instron Japan Co., Ltd.), at a test speed of 5 mm / min. The results are shown in Table 5.

[0156] As shown in Table 5, the compressive strength of Example 12 was more than twice as high as that of Comparative Example 9. This is thought to be because, in Example 12, the lignin component in the curable composition was uniformly dissolved in the polyol, allowing the lignin component and isocyanate to react uniformly, resulting in improved compressive strength. Thus, when the curable composition of the present invention is used in a polyurethane resin composition, it can be expected that the lignin component contained in the curable composition will react uniformly with the isocyanate. For this reason, the curable composition of the present invention can be suitably used to improve the compressive strength of polyurethane molded articles.

[0157] (5) Flammability Test of Rigid Polyurethane Resin This test was conducted in accordance with UL94HBF. First, the rigid polyurethane resin was machined to cut out five test pieces (N = 1 to 5) each measuring 150 mm x 50 mm x 10 mm, and a flame test was conducted on each test piece. The flame retardancy performance level is shown in Table 5 as "HF-1 > HF-2 > HBF > Not ranked." In addition, in the above-mentioned flame test, the time it took for the resin to burn with a flame when exposed to a flame for 60 seconds is shown in Table 5 as the "flame burning time after 60 seconds of flame exposure."

[0158] As shown in Table 5, in the flaming combustion time after 60 seconds of flame contact, one flaming test piece was found in Comparative Example 9, whereas no flaming test pieces were found in Example 12. From these results, it was confirmed that the rigid polyurethane resin of Example 12 had improved flame retardancy compared to the rigid polyurethane resin of Comparative Example 9.

[0159] The curable composition of the present invention can be used to produce polyurethane resins or molded articles thereof that are used in automobile parts, machine parts, industrial parts, home appliance parts, bedding and furniture, electric wires, cables, rolls, hoses, tubes, belts, films, sheets, laminated articles, coatings, adhesives, sealants, sporting goods, leisure goods, shoe-related parts, miscellaneous goods, nursing supplies, housing products, medical care, building materials, civil engineering-related products, heat insulation materials, waterproofing materials, packaging materials, heat-insulating materials, cold-insulating materials, slurry powders, vibration absorbers, etc. Furthermore, when the curable composition of the present invention is made into a polyurethane resin or molded article, it can be used in applications in which a surface material such as paper, wood, gypsum board, resin, aluminum foil, steel plate, etc. is provided on one or both sides of the polyurethane resin or molded article.

[0160] Although several embodiments and / or examples of the present invention have been described in detail above, those skilled in the art will readily be able to make numerous modifications to these exemplary embodiments and / or examples without substantially departing from the novel teachings and advantages of the present invention. Accordingly, these numerous modifications are within the scope of the present invention. The contents of all documents cited in this specification and of the applications from which this application claims priority under the Paris Convention are incorporated by reference in their entirety.

Claims

1. A lignin component containing two or more compounds represented by the following formula (1): and a polyol, The content of the lignin component is 0.1% by mass or more, The curable composition, wherein the total content of the compounds is 0.06 mass% or more based on the total amount of the lignin component. 【Chemistry 11】 (In the formula, R ａ R is a hydrogen atom, a methyl group, an ethyl group, a furyl group, a hydroxymethylfuryl group, a hydroxyphenyl group, a hydroxymethoxyphenyl group, or a hydroxydimethoxyphenyl group. ｃ１ , R ｃ２ R each independently represents a hydroxyl group, an alkoxy group, an amino group, or a thiol group. １１ ~R ２０ R each independently represents a hydrogen atom, a hydroxyl group, a hydrocarbon group having 1 to 15 carbon atoms, a hydrocarbon ether group having 1 to 15 carbon atoms, or a group containing a carbonyl group. １１ ~R ２０ may be the same or different. １１ ~R １５ At least one of R is a hydrogen atom; １６ ~R ２０ At least one of is a hydrogen atom.)

2. A lignin component containing two or more compounds represented by the following formula (1'): and a polyol, The curable composition has a total content of the compounds of 0.03% by mass or more. 【Chemistry 12】 (In the formula, R ａ R is a hydrogen atom, a methyl group, an ethyl group, a furyl group, a hydroxymethylfuryl group, a hydroxyphenyl group, a hydroxymethoxyphenyl group, or a hydroxydimethoxyphenyl group. ｃ１ , R ｃ２ R each independently represents a hydroxyl group, an alkoxy group, an amino group, or a thiol group. １１ ~R ２０ R each independently represents a hydrogen atom, a hydroxyl group, a hydrocarbon group having 1 to 15 carbon atoms, a hydrocarbon ether group having 1 to 15 carbon atoms, or a group containing a carbonyl group. １１ ~R ２０ may be the same or different. １１ ~R １５ At least one of R is a hydrogen atom; １６ ~R ２０ At least one of is a hydrogen atom.)

3. A curable composition containing a lignin component and a polyol, The lignin component has a maximum peak value of a differential distribution value (dw / dLogM) present at a molecular weight of 2.4 to 2.6 of the lignin component, which is measured by gel permeation chromatography (GPC), of 50 to 150, or a difference in integral distribution value (%) at a molecular weight of 2.4 to 2.55 of the lignin component is 5 to 15.

4. The curable composition according to any one of claims 1 to 3, wherein the content of the lignin component is 1 to 900 parts by mass based on 100 parts by mass of the polyol.

5. The curable composition according to any one of claims 1 to 3, wherein the polyol has a weight average molecular weight of 200 to 8,000.

6. The curable composition according to any one of claims 1 to 3, wherein the polyol is at least one selected from the group consisting of aromatic polyols, alicyclic polyols, aliphatic polyols, polylactone polyols, polycarbonate polyols, polyester polyols, polyether polyols, and polymer polyols.

7. The curable composition according to any one of claims 1 to 3, wherein the polyol is at least one selected from the group consisting of polyethylene glycol, polypropylene glycol, and polyester polyol.

8. The curable composition according to any one of claims 1 to 3, wherein the weight average molecular weight (Mw) of the lignin component is 1,000 to 3,000.

9. The curable composition according to any one of claims 1 to 3, wherein the molecular weight distribution (Mw / Mn) of the lignin component is 2.2 to 3.

5.

10. The curable composition according to any one of claims 1 to 3, wherein the content of the following compound (2) is 0.1 mass% or less: 【Chemistry 13】

11. The curable composition according to any one of claims 1 to 3, wherein the content of a free phenol monomer is 0.02% by mass or more and 8.0% by mass or less.

12. A polyurethane resin composition comprising the curable composition according to any one of claims 1 to 3 and an isocyanate.

13. The polyurethane resin composition according to claim 12, wherein the polyurethane resin composition is a rigid polyurethane resin composition.

14. 13. The polyurethane resin composition of claim 12, further comprising one or more additives selected from the group consisting of red phosphorus, phosphate esters, phosphate-containing flame retardants, bromine-containing flame retardants, and metal hydroxides.

15. A polyurethane molded article obtained by curing the polyurethane resin composition according to claim 12.

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