Lignin composition and use thereof

Abstract

A lignin composition comprising two or more compounds represented by the following formula (1), wherein the total content of the compounds is 0.06% by mass or more: wherein in the formula, Ra is a hydrogen atom, a methyl group, an ethyl group, a furyl group, a hydroxymethylfuryl group, a hydroxyphenyl group, a hydroxymethoxyphenol group, or a hydroxydimethoxyphenol group; Rc1 and Rc2 are independently a hydroxyl group, an alkoxy group, an amino group, or a thiol group; R11 to R20 are independently a hydrogen atom, a hydroxyl group, a hydrocarbon group including 1 to 15 carbon atoms, a hydrocarbon ether group including 1 to 15 carbon atoms, or a group containing a carbonyl group.

Description

Lignin compositions and uses thereof

[0001] The present invention relates to lignin compositions and uses thereof.

[0002] Attempts have been made to improve the mechanical properties, such as bending strength, of the resulting molded products by mixing or reacting lignin with resins. However, it is known that adding lignin to a thermosetting resin before molding generally reduces the flowability.

[0003] To address the above-mentioned problems, methods have been proposed in the past to modify lignin with phenol or the like to prevent a decrease in fluidity when resin is added. For example, Patent Document 1 discloses that molding materials obtained by adding lignin to novolac phenolic resins have poor resin flow, causing clogging and making molding impossible, while molding materials obtained by adding lignin-modified novolac phenolic resins obtained by reacting lignin, phenol or a phenol derivative, and aldehydes with novolac phenolic resins in the presence of an organic acid have improved moldability. However, Patent Document 1 has problems such as slightly lower bending strength than ordinary novolac phenolic resins, a high possibility of requiring secondary treatment of the lignin with a volatile organic base, and the use of highly toxic formaldehyde. Furthermore, Patent Document 2 discloses that reacting lignin, phenols, and aldehydes in the presence of an acid catalyst improves thermal fluidity during friction material molding and improves friction characteristics. However, Patent Document 2 has the problem that a pretreatment of lignin purification using methanol, ethanol, acetone, tetrahydrofuran, or the like is essentially required, and also has the problem of using highly toxic formaldehyde.

[0004] JP 2008-156601 A JP 2013-199561 A

[0005] A thermosetting resin with reduced fluidity due to the addition of lignin is less likely to be filled uniformly into a mold or the like during molding, which can result in molding defects such as short shots. Therefore, an object of the present invention is to provide a lignin composition that, when added to a thermosetting resin or the like, can impart fluidity suitable for molding.

[0006] According to the present invention, the following lignin compositions and the like are provided: 1. A lignin composition containing two or more compounds represented by the following formula (1), wherein the total content of the compounds is 0.06 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 hydroxymethoxyphenol group, or a hydroxydimethoxyphenol 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 which is a hydrogen atom.) 2. The lignin composition according to 1, having a weight average molecular weight (Mw) of 1,000 to 3,000. 3. The lignin composition according to 1 or 2, having a molecular weight distribution (Mw / Mn) of 2.2 to 3.5. 4. The lignin composition according to any one of 1 to 3, having a total content of compounds represented by formula (1) of 5 mass% or less. 5. The lignin composition according to any one of 1 to 4, having a content of the following compound (2) of 0.1 mass% or less: 6. The lignin composition according to any one of 1 to 5, having a free phenol monomer content of 0.02% by mass or more and 5.0% by mass or less. 7. The lignin composition according to any one of 1 to 6, having a softening point of 100°C or more and less than 250°C. 8. A lignin composition, wherein the maximum value of the peak of the differential distribution value (dw / dLogM) present at a molecular weight LogM of 2.4 to 2.6 of the lignin composition, as measured by gel permeation chromatography (GPC), is 50 to 150, or the difference in integrated distribution values ​​(%) at a molecular weight LogM of 2.4 to 2.55 of the lignin composition is 5 to 15. 9. A thermosetting resin composition comprising the lignin composition according to any one of 1 to 8 and a thermosetting resin. 10. Use of the lignin composition according to any one of 1 to 8, for promoting a crosslinking reaction in a thermosetting resin molding material containing a thermosetting resin. 11. Use of the lignin composition according to claim 10, wherein the thermosetting resin is any one or more selected from a phenolic resin, a urethane resin, an epoxy resin, a urea resin, a melamine resin, an unsaturated polyester resin, a diallyl phthalate resin, a silicone resin, an alkyd resin, and a polyimide. 12. A method for accelerating a crosslinking reaction in a thermosetting resin molding material containing a thermosetting resin, using the lignin composition according to any one of claims 1 to 8. 13. A modifier for thermosetting resins or a crosslinking reaction accelerator, comprising the lignin composition according to any one of claims 1 to 8. 14. A rubber composition comprising the lignin composition according to any one of claims 1 to 8 and a rubber material. 15. A molded article obtained by curing the thermosetting resin composition according to claim 9 or the rubber composition according to claim 14. 16. A method for producing the lignin composition according to any one of claims 1 to 8, comprising an extraction step of extracting a lignin composition containing a lignin-derived extract from a lignin-containing material using a solvent containing an organic solvent.

[0007] By using the lignin composition of the present invention, it is possible to prepare a resin composition (molding material) having flowability suitable for molding, and to obtain a resin molded product having improved physical properties such as mechanical strength.

[0008] 1 is a chart of the differential distribution value of molecular weight determined by GPC for the sample of Example 1. FIG. 2 is a chart of the integral distribution value of molecular weight determined by GPC for the sample of Example 1. FIG. 3 is a DSC curve of the lignin composition of Example 2 and the lignin of Comparative Example 1.

[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] [Lignin Composition] A lignin composition according to one embodiment of the present invention contains two or more compounds represented by the following formula (1), and the total content of the compounds is 0.06 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 hydroxymethoxyphenol group, or a hydroxydimethoxyphenol 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.)

[0011] 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.

[0012] 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.

[0013] The hydrocarbon ether group is, for example, —(CH ２ ) ａ -O-(CH ２ ) ｂ - (where a and b are integers of 0 or more, provided that a+b is 1 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 -(CH２ ) 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).

[0014] 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').

[0015] 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.

[0016] The amount of lignin contained in the lignin composition can be confirmed as a value calculated by measuring the amount of methoxyl groups contained in the lignin 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.

[0017] By containing two or more compounds represented by formula (1) (hereinafter, sometimes referred to as phenol dimers) in a predetermined amount or more, the lignin composition can maintain fluidity when incorporated into a thermosetting resin. The type and content of the phenol dimers contained in the lignin composition are confirmed by liquid chromatography-mass spectrometry (LC / MS). When the lignin composition is measured by liquid chromatography-mass spectrometry (LC / MS), the content of the phenol dimers in the entire lignin composition can be calculated. Furthermore, when the lignin composition is measured by liquid chromatography-mass spectrometry (LC / MS), the content of the phenol dimers in the entire thermosetting resin composition described below can be calculated based on the content ratio of the lignin composition to other components such as phenolic resins. In LC / MS, it is assumed that the lignin composition contains the following compounds (a) to (h) as the compound represented by formula (1). When the content of the target compound is below the detection limit, i.e., less than 0.001% by mass, the lignin composition is determined to not contain the target compound. The details of the measurement 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.

[0018] In this embodiment, for example, the lignin composition contains two or more compounds selected from the above compounds (a) to (h).

[0019] The total content of the compound represented by formula (1) relative to the entire lignin composition is 0.06% by mass or more. This allows the fluidity of the resin composition to be maintained when blended with a thermosetting resin. The total content may be 0.07% by mass or more, or 0.1% 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. The content can be appropriately adjusted depending on the thermosetting resin used, molding conditions, etc.

[0020] In one embodiment, the weight average molecular weight (Mw) of the lignin composition is 1,000 to 3,000. This makes it easier to maintain fluidity when blended with a thermosetting resin. Furthermore, a molded product with good mechanical properties is more likely to be obtained. The Mw may be 1,300 or more, or 1,500 or more. The Mw may be 2,900 or less, or 2,700 or less.

[0021] In one embodiment, the molecular weight distribution (Mw / Mn) of the lignin composition 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. Each molecular weight of the lignin composition is measured by GPC as described in the Examples below.

[0022] In one embodiment, the content of the following compound (2) relative to the total mass of the lignin composition is 0.1 mass% or less, and may be 0.05 mass% or less.

[0023] By having the content of compound (2) within the above range, loss of the solvent component due to reaction between the solvent components in the lignin extraction process described below is suppressed, and it can be said that the composition obtained is one in which the solvent appropriately participates in lignin production in the lignin extraction process. The content of compound (2) is measured by the method described in the Examples described below.

[0024] In one embodiment, the content of free phenol monomer relative to the total lignin composition is 0.02% by mass or more and 5.0% by mass or less. The free phenol monomer contained in the lignin composition is mainly a portion of the phenol used in the production of the lignin composition 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.

[0025] In one embodiment, the softening point of the lignin composition is 100° C. or higher and lower than 250° C. The softening point may be 110° C. or higher, 120° C. or higher, or 130° C. or higher. The softening point may also be 200° C. or lower, 180° C. or lower, or 160° C. or lower. The softening point is measured by the method described in the Examples below.

[0026] In another embodiment of the lignin composition of the present invention, the maximum peak value of the differential distribution value (dw / dLogM) present at molecular weights LogM of 2.4 to 2.6 of the lignin composition, as measured by GPC, is 50 to 150, or the difference in integral distribution values ​​(%) at molecular weights LogM of 2.4 to 2.55 of the lignin composition is 5 to 15. By measuring the maximum peak value of the differential distribution value (dw / dLogM) present at molecular weights LogM of 2.4 to 2.6 of the lignin composition by GPC being 50 to 150, the lignin composition can maintain fluidity when blended with a thermosetting resin. The maximum value may be 130 or less, or may be 110 or less. Similarly, by measuring the difference in integral distribution values ​​(%) at molecular weights LogM of 2.4 to 2.55 being 5 to 15, the lignin composition can maintain fluidity when blended with a thermosetting resin. The integral distribution value may be 7 or more, or may be 8 or more, or may be 13 or less, or may be 12 or less.

[0027] The lignin composition of the present invention can be obtained, for example, by extracting a lignin-containing material with a solvent containing an organic solvent, followed by purification. The solvent containing an organic solvent typically contains at least a compound represented by the following formula (I):

[0028]

[0029] 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 ~R ３５ 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, the group containing a carbonyl group is 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.

[0030] 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.

[0031] 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.

[0032] 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).

[0033]

[0034] 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 R４ When either one of the above is a hydrogen atom, the guaiacyl nucleus (G-type skeleton) is ３ and R ４ and 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.

[0035] (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, organosolv lignin, etc.), and the like, and any one or more of these can be used. Among these, from the viewpoints of ease of availability, quality of the lignin composition, 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.

[0036] 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.

[0037] 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.

[0038] A method for producing a lignin composition is, for example, as follows. One or more of the saccharification residue and fermentation residue of plant biomass are used as raw materials, and a solvent containing, for example, a compound having one or more compounds selected from the group consisting of a hydroxyl group and an ether bond (hereinafter also referred to as "organic solvent A") is added. The solvent containing organic solvent A typically contains at least the compound represented by formula (I) described above. Organic solvent A will be described in detail in the "Solvent" section below. After heating for approximately 2 to 4 hours, the heated liquid contains insoluble matter, so it is filtered using No. 2 filter paper. The filtered solid is 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 solid is the lignin composition.

[0039] Furthermore, the lignin-containing material used as a raw material can be lignin separated from non-edible plant biomass by organosolv, hot water compression, steam explosion, ammonia treatment, ammonia explosion, acid treatment, dilute sulfuric acid explosion, alkali treatment, oxidative decomposition, pyrolysis, microwave heating, or other processes. 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, a lignin composition can also be directly extracted from non-edible plant biomass by using a solvent containing organic solvent A as the organic solvent.

[0040] (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.

[0041] In one embodiment, a solvent containing organic solvent A is used. 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 composition may have reacted with the organic solvent containing organic solvent A. Using organic solvent A makes it possible to effectively extract the lignin-derived extract.

[0042] 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.

[0043] 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.

[0044] 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.)

[0045] 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.

[0046] 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.

[0047] 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; anisole, aniline, thiophenol, and the like. Preferably, it is one or more 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 one or more selected from the group consisting of phenol, catechol, resorcinol, hydroquinone, o-cresol, m-cresol, p-cresol, and anisole, even more preferably one or more selected from the group consisting of phenol, o-cresol, m-cresol, p-cresol, and anisole, even more preferably one or more selected from the group consisting of phenol and anisole, and even more preferably phenol.

[0048] When a compound represented by formula (I), such as phenol, is used as the organic solvent, the lignin composition is expected to react with the compound represented by formula (I) to increase 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).

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] When the lignin composition is extracted from the 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 composition at the highest concentration.

[0054] (Extraction) In the present invention, extraction refers to extracting a lignin composition containing a lignin-derived extract from a lignin-containing material containing components other than lignin. In one embodiment, "extraction" refers to extracting a lignin composition 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 the organic solvent) contains either a lignin-containing solid and lignin already dissolved in the solvent, or a lignin-containing solid without lignin already dissolved in the 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.

[0055] (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.

[0056] The extraction temperature is not particularly limited as long as the lignin composition can be extracted 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 composition) and promote extraction, while temperatures below 300° C. can suitably prevent the progression of lignin recombination.

[0057] The extraction time can be set appropriately, for example, 0.1 hours or more, 0.5 hours or more, 1 hour or more, or 2 hours or more, and 15 hours or less, 10 hours or less, or 8 hours or less. The extraction pressure can be set appropriately, for example, 0.1 MPa or more, 0.5 MPa or more, or 1.0 MPa or more, and 10 MPa or less, 5 MPa or less, 4 MPa or less, or 3 MPa or less.

[0058] (Purification) The lignin composition is produced by the extraction described above, but may be purified after extraction, if necessary. An example of purification will be described below.

[0059] The extracted lignin composition can be purified (purification step) by first subjecting it to a solid-liquid separation process. The extracted lignin composition is dissolved in the solvent, but 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. The lignin composition is contained in the filtrate after this filtration. Alternatively, the extracted solution 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 composition is contained in the solution. The method for performing the solid-liquid separation is not particularly limited, and examples thereof include filtration, filter press, centrifugation, dehydration, and the like. The solid-liquid separation device used for the solid-liquid separation is not particularly limited, and examples thereof include filtration devices using filters, vacuum filters, centrifuges, screw decanters, dehydrators such as belt press dehydrators, screw press dehydrators, and filter press dehydrators, and vibrating sieves. Examples of centrifuges include decanter-type and disk-type centrifuges. These solid-liquid separation devices may be used alone or in combination of two or more devices. By performing solid-liquid separation using the above-described solid-liquid separation device, solids such as unextracted components and inorganic impurities contained in the lignin composition can be efficiently and effectively removed. Therefore, a lignin composition in which the content of components other than lignin contained in the lignin-containing material is effectively reduced can be obtained without performing reprecipitation on the lignin composition obtained by distillation or vacuum drying as described below.

[0060] The solution containing the lignin composition obtained through the extraction step and, if necessary, the solid-liquid separation step may be subjected to distillation. Distillation can be performed by removing the solvent by vacuum distillation at a temperature of about 40 to 200°C, typically about 50 to 150°C, under a reduced pressure of about 3 to 20 kPa, typically about 5 to 10 kPa. The lignin composition is obtained as a solid or viscous solid in this distillation. For example, when using another dilution solvent, 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 in the extraction can be removed in the same manner as above. The lignin composition is obtained as a solid or viscous solid in this distillation.

[0061] After the extraction step or solid-liquid separation step, if necessary, the lignin composition obtained by performing either or both of the solid-liquid separation step and distillation may be subjected to a drying step in which the solvent remaining in the lignin composition (e.g., organic solvent A) is removed and purified. The drying step may be performed by heating the lignin composition to about 50 to 250°C, typically about 100 to 180°C, under a reduced pressure of, for example, about 0.1 to 10 kPa, typically about 1.0 to 5.0 kPa, and then subjecting the lignin composition to vacuum drying or other reduced-pressure drying in a solid or molten state. Alternatively, the drying step may be performed by subjecting the heated lignin composition in a fluid state after distillation to vacuum drying or other reduced-pressure drying. The drying step is not limited to the reduced-pressure drying described above. For example, the lignin composition may be subjected to air blowing under normal pressure and in an inert atmosphere (e.g., a nitrogen atmosphere) to remove the solvent remaining in the lignin composition. Examples of drying devices used for drying include thin-film dryers such as disk dryers and drum dryers, paddle dryers, agitator dryers, devolatilizing extruders, and twin-screw continuous kneaders. These drying devices may be used alone or in combination of two or more devices. By performing drying using the above-mentioned drying device, the solvent remaining in the lignin composition can be efficiently and effectively removed. Therefore, a lignin composition in which the amount of residual solvent components, such as the organic solvent used in the extraction process, is effectively reduced can be obtained without reprecipitation of the lignin composition obtained through the drying process.

[0062] The lignin composition obtained by distillation or vacuum drying is preferably not subjected to reprecipitation. This allows for easy production of a lignin composition 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.

[0063] The amount of organic solvent remaining in the lignin composition is not particularly limited, but is typically less than 30% by mass, preferably less than 10% by mass, more preferably less than 5% by mass, and even more preferably less than 1% by mass, based on the total amount of these organic solvents.

[0064] By the method for producing a lignin 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 a lignin composition, more preferably 60 mass% or more is extracted as a lignin composition, even more preferably 70 mass% or more is extracted as a lignin composition, even more preferably 80 mass% or more is extracted as a lignin composition, and even more preferably 90 mass% or more is extracted as a lignin composition.

[0065] The lignin composition of the present invention can be used as a molding material for various resins or rubbers, for example, as a modifier for thermosetting resins, a crosslinking reaction accelerator, or a rubber reinforcing material.

[0066] [Thermosetting Resin Composition] A thermosetting resin composition (molding material) according to one embodiment of the present invention comprises the lignin composition of the present invention described above and a thermosetting resin. This also includes the use of the lignin composition in the manufacturing process of the thermosetting resin. Examples of thermosetting resins include phenolic resins, urethane resins, epoxy resins, urea resins, melamine resins, unsaturated polyester resins, diallyl phthalate resins, silicone resins, alkyd resins, and polyimides.

[0067] Among these, phenolic resins, urethane resins, and epoxy resins are preferred because they can react with the lignin composition and can also be used as a diluent, with phenolic resins and urethane resins being more preferred, and phenolic resins being even more preferred. Among phenolic resins, novolac-based phenolic resins and resol-based phenolic resins are more preferred, with novolac-based phenolic resins being even more preferred. These thermosetting resins may be used alone or in combination of two or more.

[0068] Examples of epoxy resins include 2,2-bis(4'-hydroxyphenyl)propane (also called bisphenol A), bis(2-hydroxyphenyl)methane (also called bisphenol F), 4,4'-dihydroxydiphenyl sulfone (also called bisphenol S), 4,4'-dihydroxybiphenyl, resorcinol, saligenin, trihydroxydiphenyldimethylmethane, tetraphenylolethane, halogen-substituted and alkyl-substituted versions of these, butanediol, ethylene glycol, erythritol, novolak, glycerin, polyoxyalkylene, and other compounds containing two or more hydroxyl groups in the molecule, and epichlorohydrin. glycidyl ether epoxy resins synthesized from phthalic acid glycidyl ester or the like; glycidyl ester epoxy resins synthesized from a compound containing two or more hydroxyl groups in the molecule and glycidyl phthalate or the like; glycidyl group-containing epoxy resins such as glycidyl amine epoxy resins synthesized from a primary or secondary amine such as aniline, diaminodiphenylmethane, metaxylenediamine, 1,3-bisaminomethylcyclohexane and the like and epichlorohydrin or the like; and glycidyl group-free epoxy resins such as epoxidized soybean oil, epoxidized polyolefin, vinylcyclohexene dioxide, dicyclopentadiene dioxide, etc. Among these, cresol novolac epoxy resins and phenol novolac epoxy resins are preferred, which have a chemical structure similar to lignin and are therefore highly compatible.

[0069] The content of the lignin composition in the thermosetting resin composition may be determined depending on the purpose. From the viewpoint of obtaining good physical properties and moldability, the content is preferably 5 to 300 parts by mass, more preferably 10 to 100 parts by mass, and even more preferably 20 to 100 parts by mass relative to 100 parts by mass of the thermosetting resin.

[0070] (Filler) In one embodiment, the thermosetting resin composition may further contain a filler. The filler may be an inorganic filler or an organic filler. Examples of inorganic fillers include silica powders such as spherical or crushed fused silica and crystalline silica, alumina powder, glass powder, glass fiber, glass flakes, mica, talc, calcium carbonate, alumina, hydrated alumina, boron nitride, aluminum nitride, silicon nitride, silicon carbide, titanium nitride, zinc oxide, tungsten carbide, and magnesium oxide. Examples of organic fillers include carbon fiber, aramid fiber, paper powder, wood flour, cellulose fiber, cellulose powder, rice husk powder, fruit shell / nut powder, chitin powder, and starch.

[0071] The inorganic filler and the organic filler may be used alone or in combination of two or more, and the content thereof is determined depending on the purpose. When an inorganic filler and / or an organic filler is contained, it is desirable that the content of the inorganic filler and / or the organic filler is appropriate to obtain good physical properties and moldability. From this viewpoint, the content of the inorganic filler and / or the organic filler is preferably 50 to 200 parts by mass, more preferably 80 to 150 parts by mass, per 100 parts by mass of the total of the thermosetting resin and the lignin composition.

[0072] (Curing Agent) The thermosetting resin composition may further contain a curing agent. When the thermosetting resin is a phenolic resin, examples of the curing agent include hexamethylenetetramine (hexamine), hexaformaldehyde, and paraformaldehyde. These may be used alone or in combination of two or more. When the thermosetting resin is a urethane resin, examples of polyisocyanates that can be used as curing agents include aromatic polyisocyanates such as tolylene diisocyanate (TDI), 4,4'-diphenylmethane diisocyanate (MDI), polymeric MDI (MDI-CR), and carbodiimide-modified MDI (liquid MDI), as well as aliphatic polyisocyanates such as norbornane diisocyanate (NBDI), isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), 4,4'-methylene-bis(cyclohexyl isocyanate) (hydrogenated MDI), and xylylene diisocyanate (XDI), and blocked isocyanates. These may be used alone or in combination of two or more. When the thermosetting resin is an epoxy resin, a lignin composition is used as a curing agent, and in this case, an epoxy resin may be used in combination with a novolac-based phenolic resin. In addition to the curing agent, inorganic bases such as calcium hydroxide, sodium hydroxide, potassium hydroxide, calcium oxide, and magnesium oxide, Lewis acids such as zinc chloride and zinc acetate, catalysts such as triethylamine, organometallic catalysts such as zirconium and aluminum, dibutyltin laurate, phenol salts of DBU, octylate salts, amines, imidazoles, ammonium salts, phosphines, phosphonium salts, etc. may be used alone or in combination of two or more.

[0073] (Other Additives) Various additives can be added to the thermosetting resin composition according to this embodiment as long as they do not impair the properties of the molded article obtained from the thermosetting resin composition. Furthermore, compatibilizers, surfactants, etc. can also be added depending on the purpose. Examples of compatibilizers include resins obtained by adding maleic anhydride, epoxy, or the like to a thermoplastic resin to introduce polar groups, such as maleic anhydride-modified polyethylene resins and maleic anhydride-modified polypropylene resins, and various commercially available compatibilizers. Examples of surfactants that can be used include, but are not limited to, straight-chain fatty acids such as stearic acid, palmitic acid, and oleic acid, and branched or cyclic fatty acids with rosins.

[0074] In addition to the above, other additives that can be added include flexibilizers, heat stabilizers, ultraviolet absorbers, flame retardants, antistatic agents, antifoaming agents, thixotropy-imparting agents, mold release agents, antioxidants, plasticizers, stress-reducing agents, coupling agents, dyes, light scattering agents, small amounts of thermoplastic resins, etc. These may be used alone or in combination of two or more.

[0075] (Kneading and Molding) The components used in the thermosetting resin composition can be blended and kneaded by premixing using commonly used equipment such as a ribbon blender or drum tumbler, followed by using a Henschel mixer, Banbury mixer, single-screw extruder, twin-screw extruder, multi-screw extruder, roll kneader, co-kneader, or the like. The heating temperature during kneading is usually selected appropriately within the range of 100 to 300°C. The method for molding the thermosetting resin composition is not particularly limited. Examples include press molding, injection molding, transfer molding, medium-sized molding, and FRP molding.

[0076] Examples of molded articles using the thermosetting resin composition include heat insulating materials (for homes, insulating equipment such as refrigerators, and for ships and vehicles), electronic parts, resins for frac sand, resins for coated sand, impregnation resins, lamination resins, prepregs, decorative sheets, bonding materials, friction materials, resins for FRP molding, binders, adhesives, paints, inks, sealing materials, sliding materials, carbon materials, automobile parts, reinforcing materials for automobile tires, office automation equipment, machinery, information and communication equipment, and industrial materials.

[0077] [Rubber Composition] A rubber composition according to one embodiment of the present invention includes the lignin composition of the present invention described above and a rubber material. Examples of rubber materials include various natural rubbers and various synthetic rubbers. Specific examples include natural rubber (NR), modified natural rubber, styrene butadiene rubber (SBR), butadiene rubber (BR), isoprene rubber (IR), butyl rubber (IIR), ethylene propylene diene rubber (EPDM), acrylonitrile butadiene rubber (NBR), and chloroprene rubber (CR). These may be used alone or in combination of two or more.

[0078] The amount of rubber material added is not particularly limited, but is preferably 100 to 10,000 parts by mass per 100 parts by mass of the lignin composition, which can sufficiently ensure the reinforcing effect of the rubber composition while preventing the rubber composition from becoming too hard and reducing elongation.

[0079] The rubber composition of this embodiment may contain a filler in addition to the above-mentioned components. Fillers that are commonly used in rubber compositions, such as carbon black, silica, alumina, and cellulose fiber, can be used. The content of the filler is preferably 10 to 150 parts by mass per 100 parts by mass of the rubber material.

[0080] In one embodiment, the rubber composition may also contain a crosslinking agent. The crosslinking agent is not particularly limited as long as it can crosslink either or both of the rubber material and the lignin composition. Furthermore, the rubber composition may also contain, for example, a softener, a tackifier, an antioxidant, an antiozonant, an antiaging agent, sulfur or other vulcanizing agents, a vulcanization accelerator, a vulcanization accelerator aid, a peroxide, zinc oxide, or stearic acid.

[0081] The rubber composition can be produced by, for example, kneading a rubber material, a lignin composition, and other raw materials. If necessary, any raw materials may be premixed and then kneaded. The order in which the above-mentioned raw materials are kneaded is not particularly limited. All raw materials may be kneaded simultaneously, or they may be kneaded sequentially in any order.

[0082] A cured product (molded article) of the rubber composition can be obtained by molding and curing the rubber composition. The molding method varies depending on the application and is not particularly limited. When molding using a mold, the rubber composition is molded using a mold equipped with a hydraulic press. This results in a cured product of the rubber composition molded into the desired shape. The molded article obtained by curing the rubber composition of this embodiment can be used for tires, etc.

[0083] [Preparation of Lignin Composition] 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) and 272 parts by mass of phenol were placed in a pressure-resistant vessel capable of stirring, and heated and stirred at 0.8 MPa and 220°C for 4 hours.

[0084] (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.

[0085] (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.

[0086] (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 composition.

[0087] Example 2 A lignin composition was obtained in the same manner as in Example 1, except that the amount of phenol was 245 parts by mass, the amount of water was 27 parts by mass, the extraction pressure was 1.7 MPa, and the extraction time was 2 hours.

[0088] Example 3 A lignin composition was obtained in the same manner as in Example 1, except that the amount of phenol was 55 parts by mass, the amount of water was 27 parts by mass, the amount of ethanol was 190 parts by mass, the extraction pressure was 2.8 MPa, and the extraction time was 2 hours.

[0089] Comparative Example 1 500 g of bagasse (dried sugarcane pomace) was heat-treated at 200°C for 2 hours in the presence of 2100 mL of 1-butanol and 3300 mL of water. The mixture was filtered (using No. 2 filter paper) to remove cellulose-containing solids. The aqueous layer was separated from the filtrate, and the 1-butanol layer was extracted. The extracted 1-butanol layer was concentrated and dried to obtain lignin.

[0090] Comparative Example 2 Kraft lignin (Lignin, alkaline (product number 370959) manufactured by SIGMA-ALDRICH) was evaluated.

[0091] [Analysis of Lignin Compositions] The lignin compositions of Examples 1 to 3 and Comparative Examples 1 and 2 were evaluated for the following items. (1) Average Molecular Weight 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, a measurement sample was prepared by dissolving the sample in tetrahydrofuran. Two general-purpose organic columns packed with a styrene-based polymer filler, "TSKgel GMHXL (manufactured by Tosoh Corporation)" and one "G2000HXL (manufactured by Tosoh Corporation)," were connected in series. 100 μL of the measurement sample was injected into a GPC system "HLC-8220GPC (manufactured by Tosoh Corporation)" or "HLC-8420GPC (manufactured by Tosoh Corporation)." 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 standard polystyrenes prepared separately. The following standard polystyrenes were used for preparing the calibration curve: Standard polystyrene for calibration curve: "TSKgel" manufactured by Tosoh Corporation (weight average molecular weight: 590 (type A-500), 1,010 (type A-1000), 2,630 (type A-2500), 5,970 (type A-5000), 10,200 (type F-1), 18,100 (type F-2), 37,900 (type F-4), 96,400 (type F-10), 190,000 (type F-20), 427,000 (type F-40), 706,000 (type F-80), 1,090,000 (type F-128), 4,480,000 (type F-450)). Note that, for the kraft lignin of Comparative Example 2, some insoluble components were generated in tetrahydrofuran, so the soluble components were the subject of analysis.

[0092] 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 Value of Differential Distribution Value (dw / dLogM) In a chart of the molecular weight of the sample determined 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 defined as the "maximum value of the differential distribution value (dw / dLogM)." Figure 1 shows a chart of the differential distribution value of the molecular weight determined by GPC for the sample of Example 1 (plotted with dw / dLogM on the y-axis and LogM on the x-axis). In Figure 1, in the molecular weight range of LogM of 2.4 to 2.6, the peak of the differential distribution value (dw / dLogM) appears at LogM = 2.5, and this differential distribution value (dw / dLogM) was defined as the "maximum value of the differential distribution value (dw / dLogM)." (c) Molecular weight Log M2.4 integral distribution value (%), molecular weight Log M2.55 integral distribution value (%) In the chart of the molecular weight of the sample determined by GPC (the y-axis is the integral distribution value (%) and the x-axis is Log M plotted), the integral distribution value (%) at molecular weight Log M2.4 and the integral distribution value (%) at molecular weight Log M2.55 were designated as the "molecular weight Log M2.4 integral distribution value" and the "molecular weight Log M2.55 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 designated as the "integral distribution value (%) 2.55-2.4." Figure 2 shows a chart of the molecular weight integral distribution value determined by GPC for the sample of Example 1 (the y-axis is the integral distribution value (%) and the x-axis is Log M plotted).In FIG. 2 , the integral distribution value at molecular weight Log M2.4 is 4.8 (%), and the integral distribution value at molecular weight Log M2.55 is 16.8 (%), and the difference between these (integral distribution value at molecular weight Log M2.55 (%) - integral distribution value at molecular weight Log M2.4 (%)) was defined as "integral distribution value (%) 2.55 - 2.4."

[0093] (2) Phenol Content The phenol content was measured using high-performance liquid chromatography (HPLC). Specifically, 50 mg of a sample such as a lignin composition was dissolved in 0.5 mL of tetrahydrofuran, 4.5 mL of a 4 / 1 (volume ratio) water / acetonitrile mixed solvent was added, and the mixture was stirred for 30 minutes. 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 spectrophotometer (UV) at 280 nm in the detection section. The phenol content in the sample was calculated from a calibration curve of a standard phenol solution prepared separately.

[0094] (3) Phenol dimer (compound represented by formulas (1) and (2)) The content of the phenol dimer was measured using liquid chromatography-mass spectrometry (LC / MS). Specifically, 50 mg of a sample such as a lignin composition 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" with a BEH C18 (1.7 μm × 2.1 mm × 50 mm) column connected to the separation section and a "Xevo G2-XS QTof" detector. 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 dimers contained in the sample were identified from the mass-to-charge ratios as 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 standard 2,2'-dihydroxydiphenylmethane solution prepared separately.

[0095]

[0096] (4) Softening Point: A sample such as a lignin composition was crushed in a mortar, and 10 to 20 mg of the crushed sample was placed in an aluminum cup (circular upper diameter: 60 mm, lower diameter: 53 mm, depth: 15 mm). The aluminum cup containing the sample was placed on a hot plate (IKA C-MAG HP7) and covered with aluminum foil. After heating to 100°C, the temperature was increased in 10°C increments, and visual observation was performed. The temperature at which the sample melted visually was used as the softening point.

[0097] (5) Differential Scanning Calorimetry (DSC) Measurement: 100 parts by weight of lignin or phenolic resin and 15 parts by weight of hexamethylenetetramine (special reagent grade) were mixed in a vial, and 500 parts by weight each of methanol and acetone were added, followed by shaking for 5 minutes. The vial was then heated to 40°C, and 100 parts by weight of methanol was added and the mixture was shaken to completely dissolve the solids. The resulting solution was air-dried overnight, and then the solvent was completely removed in a vacuum dryer at 40°C. The resulting lignin / hexamethylenetetramine mixture was pulverized in a mortar to obtain a measurement sample. Differential scanning calorimetry (DSC) was performed using a Hitachi High-Tech Science GCA-0017. 10 mg of the measurement sample prepared by the above method was sealed in an aluminum sealed container (15 μL) and measured under the following conditions: measurement range: 30 to 240°C, measurement atmosphere: nitrogen (100 mL / min). Al was used as a reference. ２ O ３ (10 mg) was used. From the obtained results, the curing exothermic peak temperature and the amount of heat generated were calculated. For reference, the DSC peak temperature of phenolic resin (manufactured by Sumitomo Bakelite Co., Ltd., product name: PR-53195) was 143°C, and the peak area was 117 J / g. The evaluation results are shown in Table 1.

[0098]

[0099] Figure 3 shows the DSC curves for the lignin composition of Example 2 and the lignin of Comparative Example 1. Figure 3 confirms that the peak temperature of the lignin composition of Example 2 is shifted to a lower temperature compared to the lignin of Comparative Example 1. This is because the curing reaction of the lignin composition of Example 2 begins at a lower temperature and exhibits reactivity closer to that of phenolic resins, which is expected to improve the uniformity of molded articles made from the lignin composition and resin compositions containing phenolic resins. Furthermore, the lignin composition of Example 2 has a wider peak area (i.e., a larger heat of reaction) compared to the lignin of Comparative Example 1. This indicates higher reactivity. Therefore, when the lignin composition of Example 2 is used in a thermosetting resin molding material, it is expected that the crosslinking reaction will be accelerated.

[0100] [Resin Composition and Molded Article] Example 4 (1) Preparation of Resin Composition A separable flask equipped with a stirrer was charged with a phenolic resin (manufactured by Sumitomo Bakelite Co., Ltd., product name: PR-53195, softening point 115°C) and the lignin composition prepared in Example 1 at a mass ratio (phenolic resin:lignin composition) of 7:3. The mixture was heated to 130°C and stirred and mixed in a molten state for 30 minutes. The treated product was removed from the flask in a molten state to obtain a mixture of the lignin composition and phenolic resin. To 50 parts by mass of the obtained mixture, 7 parts by mass of hexamethylenetetramine (curing agent: manufactured by Kanto Chemical Co., Inc.) were added at room temperature, and the mixture was mixed for 5 minutes using a mixing machine. Thereafter, 50 parts by mass of glass fiber (glass milled fiber, manufactured by Nitto Boseki Co., Ltd., PF80E-401) as a filler, and 1 part by mass of magnesium stearate (lubricant: manufactured by ADEKA Corporation) and 1 part by mass of magnesium oxide (accelerator: manufactured by Kyowa Chemical Industry Co., Ltd.) as additives were blended and mixed for approximately 5 minutes using a mortar and pestle. The resulting mixture was kneaded with a heated roll at 120°C for 7 minutes, cooled, and pulverized to obtain a resin composition (molding material). The composition of the resin composition is shown in Table 2.

[0101] (2) Evaluation of fluidity of resin composition (spiral flow) The obtained resin composition was compressed at 15 tf at room temperature to prepare tablets. After preheating at 90 ° C for 10 minutes in a hot air circulation oven, the tablets were placed in a transfer molding machine (MF-O15: manufactured by Marushichi Co., Ltd.). Molding was performed in a spiral flow mold under conditions of 165 ° C, 40 MPa, and 5 minutes, and the length of flow of the resin composition was measured. The evaluation results are shown in Table 2.

[0102] (3) Molding of Resin Composition The resin composition prepared in (1) above was compressed at 15 tf at room temperature to produce tablets. The tablets were preheated at 90°C for 10 minutes in a hot air circulation oven and then placed in a transfer molding machine (MF-O15: manufactured by Marushichi Co., Ltd.). Transfer molding was performed on a test specimen mold (10 mm x 80 mm x 4 mm thick) at 165°C, 40 MPa, and 3 minutes. The molded product (cured product of the phenol-modified lignin resin composition) was then obtained by heat treatment at 180°C for 8 hours.

[0103] (4) Evaluation of Physical Properties of Molded Articles The molded articles (test pieces) obtained in (3) above were measured for flexural modulus, flexural strength, and flexural strain in accordance with JIS K 7171 "Plastics - Determination of flexural properties." Specifically, a three-point bending test was performed using a universal testing machine (Model 5966, manufactured by Instron) at a speed of 2 mm / min with a load applied at a support distance of 64 mm.

[0104] Furthermore, moldability was evaluated according to the following criteria: A: Good B: Slight overflow from the mold, but no problem C: Partial short D: Completely short E: Overflow from the mold, quality not within acceptable range Furthermore, voids inside the molded body were visually evaluated using X-ray CT. Those with uniform voids inside the molded body were rated "Y", and those with no voids or voids only partially inside the molded body were rated "X". The evaluation results are shown in Table 2.

[0105]

[0106] Examples 5 and 6 and Comparative Examples 3 and 4 Resin compositions and molded articles were prepared and evaluated in the same manner as in Example 4, except that the lignin compositions or lignins prepared in Examples 2 and 3 and Comparative Examples 1 and 2 were used instead of the lignin composition prepared in Example 1.

[0107] 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 composition comprising two or more compounds represented by the following formula (1), the total content of said compounds being 0.06 mass% or more: (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 hydroxymethoxyphenol group, or a hydroxydimethoxyphenol 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. The lignin composition according to claim 1, having a weight average molecular weight (Mw) of 1,000 to 3,000.

3. The lignin composition according to claim 1 or 2, having a molecular weight distribution (Mw / Mn) of 2.2 to 3.

5.

4. A lignin composition according to any one of claims 1 to 3, wherein the total content of the compound represented by formula (1) is 5 mass% or less.

5. The lignin composition according to any one of claims 1 to 4, wherein the content of the following compound (2) is 0.1 mass% or less:

6. A lignin composition described in any one of claims 1 to 5, having a free phenol monomer content of 0.02 mass% or more and 5.0 mass% or less.

7. A lignin composition according to any one of claims 1 to 6, having a softening point of 100°C or higher and lower than 250°C.

8. A lignin composition, in which the maximum peak value of the differential distribution value (dw / dLogM) present at molecular weights LogM of 2.4 to 2.6 of the lignin composition is 50 to 150, or the difference in integral distribution values ​​(%) at molecular weights LogM of 2.4 to 2.55 of the lignin composition is 5 to 15, as measured by gel permeation chromatography (GPC).

9. A thermosetting resin composition comprising the lignin composition according to any one of claims 1 to 8 and a thermosetting resin.

10. Use of the lignin composition according to any one of claims 1 to 8 for promoting a crosslinking reaction in a thermosetting resin molding material containing a thermosetting resin.

11. Use of the lignin composition according to claim 10, wherein the thermosetting resin is at least one selected from the group consisting of phenolic resins, urethane resins, epoxy resins, urea resins, melamine resins, unsaturated polyester resins, diallyl phthalate resins, silicone resins, alkyd resins and polyimides.

12. A method for promoting a crosslinking reaction in a thermosetting resin molding material containing a thermosetting resin, using the lignin composition according to any one of claims 1 to 8.

13. A modifier or crosslinking reaction accelerator for thermosetting resins, comprising the lignin composition according to any one of claims 1 to 8.

14. A rubber composition comprising the lignin composition according to any one of claims 1 to 8 and a rubber material.

15. A molded article obtained by curing the thermosetting resin composition according to claim 9 or the rubber composition according to claim 14.

16. A method for producing a lignin composition according to any one of claims 1 to 8, comprising an extraction step of extracting a lignin composition containing a lignin-derived extract from a lignin-containing material using a solvent containing an organic solvent.