Lignin composition and use of same

Abstract

A lignin composition containing two or more compounds represented by formula (1), wherein the total amount of the compounds is 0.50 mass% or more.

Description

Lignin compositions and uses thereof

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

[0002] Conventionally, attempts have been made to improve mechanical properties such as bending strength of the resulting molded product by adding lignin modified with an acid or the like to a resin (Patent Document 1).

[0003] However, the addition of lignin to thermosetting resins increases their viscosity and reduces their flowability. In view of this problem, it has been disclosed that adding a lignin composition containing a specific phenol dimer in a specific total content to a thermosetting resin can maintain flowability suitable for molding and improve physical properties such as the mechanical strength of the molded body (Patent Document 2).

[0004] International Publication No. 2015 / 147165 Japanese Patent Application Laid-Open No. 2022-104522

[0005] However, it has been found that there is room for further improvement in conventional technologies such as those described in Patent Documents 1 and 2, in terms of improving the fluidity when the lignin composition is added to a thermosetting resin and improving the surface smoothness of the molded body.

[0006] One of the objects of the present invention is to provide a lignin composition that can improve mechanical properties, significantly suppress a decrease in fluidity, and improve the surface smoothness of molded bodies when added to thermosetting resins, etc.

[0007] As a result of extensive research, the present inventors discovered that a lignin composition containing a specific phenol trimer in a specific total content can improve mechanical properties, significantly suppress a decrease in fluidity, and improve the surface smoothness of molded articles when added to thermosetting resins, etc., and completed the present invention. The present invention provides the following lignin compositions, etc.: 1. A lignin composition containing two or more compounds represented by the following formula (1), wherein the total content of the compounds is 0.50 mass% or more: (In formula (1), R ａ represents a trivalent saturated hydrocarbon group having 1 to 3 carbon atoms. ａThe single bonds *, **, and *** in the formula R are bonded to any of the carbon atoms constituting the corresponding benzene ring. １１ ~R １５ One of them is R ａ It is a single bond that bonds to R ２１ ~R ２５ One of them is R ａ It is a single bond that bonds to R ３１ ~R ３５ One of them is R ａ It is a single bond that bonds to R ａ R is not a single bond bonded to １１ ~R １５ , R ２１ ~R ２５ and R ３１ ~R ３５ respectively represent a hydrogen atom, a methoxy group, a hydroxy group, a furyl group, a hydroxymethylfuryl group, a hydroxyphenyl group, a hydroxymethoxyphenol group, or a hydroxydimethoxyphenol group.) 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 1.0 to 4.0. 4. The lignin composition according to any one of 1 to 3, having a total content of the compound represented by formula (1) of 0.05 to 5 mass%. 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. A 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. A 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 difference in integral distribution value (%) at molecular weights LogM of 2.55 and 2.73 of the lignin composition, as measured by gel permeation chromatography (GPC), is 15 to 25. 9. A lignin composition, wherein the maximum value of the peak of the differential distribution value (dw / dLogM) present at molecular weights LogM of 2.60 to 2.75 of the lignin composition, as measured by gel permeation chromatography (GPC), is 80 to 250. 10. A thermosetting resin composition comprising the lignin composition according to any one of 1 to 9, and a thermosetting resin. 11. The thermosetting resin composition according to claim 10, wherein the thermosetting resin comprises one or more selected from the group consisting of a phenolic resin, a urethane resin, an epoxy resin, a urea (urea) resin, a melamine resin, an unsaturated polyester resin, a diallyl phthalate resin, a silicone resin, an alkyd resin, and a polyimide. 12. Use of the lignin composition according to any one of claims 1 to 9 for promoting a crosslinking reaction in a thermosetting resin molding material comprising a thermosetting resin. 13. Use of the lignin composition according to claim 12, wherein the thermosetting resin comprises one or more selected from the group consisting of a phenolic resin, a urethane resin, an epoxy resin, a urea (urea) resin, a melamine resin, an unsaturated polyester resin, a diallyl phthalate resin, a silicone resin, an alkyd resin, and a polyimide. 14. A method for promoting a crosslinking reaction in a thermosetting resin molding material comprising a thermosetting resin, using the lignin composition according to any one of claims 1 to 9. 15. A modifier for thermosetting resins or a crosslinking reaction accelerator for thermosetting resins, comprising the lignin composition according to any one of claims 1 to 9. 16. A rubber composition comprising the lignin composition according to any one of 1 to 9 and a rubber material. 17. A molded article obtained by curing the thermosetting resin composition according to 10 or the rubber composition according to 16.

[0008] According to the present invention, a lignin composition can be provided that can improve mechanical properties, significantly suppress a decrease in fluidity, and improve the surface smoothness of molded bodies when added to thermosetting resins, etc.

[0009] Chart of molecular weight differential distribution values ​​determined by gel permeation chromatography (GPC) (Example 1)

[0010] Hereinafter, in this specification, "x to y" represents a numerical range of "greater than or equal to x and less than or equal to y." The upper and lower limits of the numerical ranges can be arbitrarily combined. Furthermore, among the individual embodiments of the aspects according to the present invention described below, two or more embodiments that are not mutually contradictory can be combined, and an embodiment combining two or more embodiments is also an embodiment of the aspects according to the present invention.

[0011] 1. Lignin Composition The lignin composition according to the first aspect of the present invention contains two or more compounds represented by the following formula (1), and the total content of the compounds is 0.50 mass% or more.

[0012]

[0013] In formula (1), R ａ represents a trivalent saturated hydrocarbon group having 1 to 3 carbon atoms. ａ The single bonds *, **, and *** in the formula R are bonded to any of the carbon atoms constituting the corresponding benzene ring. １１ ~R １５ One of them is R ａ It is a single bond that bonds to R ２１ ~R ２５ One of them is R ａ It is a single bond that bonds to R ３１ ~R ３５ One of them is R ａ It is a single bond that bonds to R ａ R is not a single bond bonded to １１ ~R １５ , R ２１ ~R ２５ and R ３１ ~R ３５ respectively represent a hydrogen atom, a methoxy group, a hydroxy group, a furyl group, a hydroxymethylfuryl group, a hydroxyphenyl group, a hydroxymethoxyphenol group, or a hydroxydimethoxyphenol group.

[0014] The lignin composition of this embodiment can improve mechanical properties by adding it to thermosetting resins and the like, and can significantly suppress a decrease in fluidity when added to thermosetting resins and the like. Therefore, due to its fluidity, thermosetting resins to which the lignin composition of this embodiment has been added can be easily and uniformly filled into molds and the like during molding, significantly preventing molding defects such as short shots. Therefore, the resulting molded body has excellent dimensional accuracy and can favorably exhibit improved mechanical properties. Furthermore, particularly compared to the technology of Patent Document 2 (a lignin composition containing a specific phenol dimer at a specific total content), the lignin composition can significantly suppress a decrease in fluidity when added to thermosetting resins and the like, significantly improving moldability. Furthermore, mechanical properties (flexural strength and flexural modulus) are also further improved. Furthermore, because the lignin composition exhibits excellent compatibility with thermosetting resins, the resulting molded body has a remarkable effect of improving the surface smoothness (smoothness) of the molded body.

[0015] With respect to the compound represented by formula (1), R ａ Examples of the trivalent saturated hydrocarbon group having 1 to 3 carbon atoms and represented by the formula (1) include the saturated hydrocarbon groups shown below. In the saturated hydrocarbon groups shown below, the single bonds *, **, and *** each bond to any of the carbon atoms constituting the corresponding benzene ring in formula (1).

[0016]

[0017] 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.

[0018] 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).

[0019]

[0020] 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 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.

[0021] The lignin composition of this embodiment (as well as the second and third embodiments described below) is a composition containing the above-mentioned lignin. The lignin content in the lignin composition is, for example, 80 to 95 mass%. In particular, the lignin composition of this embodiment (first embodiment) is characterized by containing, in addition to lignin, two or more compounds (phenol trimers) represented by formula (1), as described above.

[0022] The type and content of phenol trimers contained in a lignin composition are confirmed by liquid chromatography-mass spectrometry (LC / MS). When LC / MS measurements are performed on a lignin composition, the content of phenol trimers in the entire lignin composition can be calculated. Furthermore, when LC / MS measurements are performed on a lignin composition, the content of phenol trimers 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 resin. In LC / MS, it is assumed that the lignin composition contains the following compounds (a) to (e) as compounds represented by formula (1). If 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 be free of the target compound. Details of the measurements are described in the Examples.

[0023]

[0024] In one embodiment, the lignin composition comprises two or more compounds selected from compounds (a) to (e). In one embodiment, the lignin composition has a total content of compounds (a) to (e) of 0.50 wt% or more.

[0025] In one embodiment, the total content of the compounds represented by formula (1) (or the total content of compounds (a) to (e)) relative to the entire lignin composition is, for example, 0.50% by mass or more, 0.60% by mass or more, 0.70% by mass or more, 0.80% by mass or more, 0.90% by mass or more, 1.00% by mass or more, 1.10% by mass or more, or 1.20% by mass or more, and 5.00% by mass or less, 4.00% by mass or less, 3.00% by mass or less, 2.00% by mass or less, or 1.50% by mass or less. In one embodiment, the total content of the compounds represented by formula (1) (or the total content of compounds (a) to (e)) relative to the entire lignin composition is 0.50 to 5.00% by mass, 0.60 to 4.00% by mass, 0.70 to 3.00% by mass, 0.80 to 2.00% by mass, or 0.90 to 1.50% by mass. The total content of the compound represented by formula (1) relative to the entire lignin composition can be appropriately adjusted depending on, for example, the thermosetting resin used, molding conditions, etc.

[0026] 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.

[0027] In one embodiment, the molecular weight distribution (Mw / Mn) of the lignin composition is 1.0 to 4.0. Mw / Mn may be 1.5 or more, 2.0 or more, 2.3 or more, 2.4 or more, 2.5 or more, or 2.6 or more. Furthermore, 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.

[0028] 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.

[0029]

[0030] 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.

[0031] 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, or 2.0% by mass or more. The phenol content is measured by the method described in the Examples below.

[0032] 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 105° C. or higher, 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.

[0033] In one embodiment, 90% by mass or more, 95% by mass or more, 98% by mass or more, 99% by mass or more, 99.5% by mass or more, or substantially 100% by mass of the lignin composition is lignin, a compound represented by formula (1), a compound represented by formula (2), and phenol (free phenol monomer), or lignin, a compound represented by formulas (a) to (e), a compound represented by formula (2), and phenol (free phenol monomer). Note that "substantially 100% by mass" may contain inevitable impurities.

[0034] In one embodiment, the ratio of the compound represented by formula (1) (or the compound represented by formulas (a) to (e)) is 0.4 to 1.8 parts by mass per 100 parts by mass of lignin contained in the lignin composition. In one embodiment, the ratio of the compound represented by formula (2) is 0.003 to 0.1 parts by mass per 100 parts by mass of lignin contained in the lignin composition. In one embodiment, the ratio of phenol (free phenol monomer) is 0.8 to 3.0 parts by mass per 100 parts by mass of lignin contained in the lignin composition. The content of each component per 100 parts by mass of lignin described here can also be maintained in the thermosetting resin composition and molded article described below.

[0035] The lignin composition according to the second aspect of the present invention has a difference in integral distribution value (%) at molecular weights LogM 2.55 and 2.73 of the lignin composition, as measured by GPC, of ​​15 to 25. The lignin composition of this aspect can provide the same effects as the lignin composition of the first aspect.

[0036] In one embodiment, the difference is 15 or more, 16 or more, or 17 or more, and 25 or less, 24 or less, or 23 or less.

[0037] In one embodiment, the lignin composition has a differential distribution value (dw / dLogM) peak value measured by GPC at a molecular weight LogM of 2.40 to 2.60 of the lignin composition, of which the maximum value is 50 or more and 150 or less. In one embodiment, the maximum value is 50 or more, 55 or more, 60 or more, 65 or more, or 70 or more, and is 150 or less, 140 or less, 130 or less, 120 or less, 110 or less, or 105 or less.

[0038] The lignin composition according to the third aspect of the present invention has a differential distribution value (dw / dLogM) of 80 to 250, the maximum peak value of which is present at a molecular weight LogM of 2.60 to 2.75, as measured by GPC. The lignin composition according to this aspect can achieve the same effects as the lignin composition according to the first aspect.

[0039] In one embodiment, the maximum value is 80 or more, 85 or more, 90 or more, 95 or more, or 100 or more, and 250 or less, 230 or less, 200 or less, 180 or less, or 150 or less.

[0040] In one embodiment, the lignin composition has a difference in integral distribution value (%) at molecular weights LogM 2.40 and 2.55 of the lignin composition, as measured by GPC, of ​​5 to 25. In one embodiment, the difference is 5 or more, 6 or more, 7 or more, 8 or more, 9 or more, or 10 or more, and is 25 or less, 20 or less, 18 or less, 16 or less, 15 or less, 14 or less, or 13 or less.

[0041] Although three aspects of the present invention have been described above, two or more of these individual aspects can be combined, and an aspect combining two or more aspects is also an aspect of the present invention. Also, an embodiment described for one aspect can be combined with another aspect.

[0042] The lignin compositions of the present invention (lignin compositions according to the first to third aspects) can be suitably produced by the method according to the first or second embodiment described below.

[0043] In a first embodiment, the lignin composition of the present invention is extracted with a solvent from acid-treated woody biomass. Examples of woody biomass include conifers and broad-leaved trees such as cedar, cypress, Japanese cypress, cherry, eucalyptus, beech, and bamboo. The acid treatment is carried out, for example, by immersing the woody biomass in an aqueous solution containing sulfuric acid. The acid treatment separates (removes) the cellulose and hemicellulose contained in the woody biomass into the aqueous solution. From this perspective, "acid-treated woody biomass" can also be rephrased as "woody biomass from which some or all of the cellulose and hemicellulose have been removed." A mixed solvent of phenol and water is suitable as the solvent used for extraction. The mass ratio of phenol to water (phenol:water) is preferably 100:5 to 20. Furthermore, it is preferable that phenol and water account for 90% by mass or more, 95% by mass or more, 99% by mass or more, 99.5% by mass or more, 99.9% by mass or more, or substantially 100% by mass of the solvent used for extraction. In the case of "substantially 100% by mass," unavoidable impurities may be contained. It is preferable that the solvent used for extraction does not contain acid or alkali. During extraction, it is preferable to heat and pressurize the acid-treated woody biomass while immersed in the solvent for a predetermined period of time. The heating temperature is preferably 120 to 220°C. The pressure is preferably 0.5 to 1.7 MPa. The heating and pressurization time is preferably 1 to 3 hours. During extraction, a pressure vessel capable of stirring the acid-treated woody biomass and the solvent can be used.

[0044] In a second embodiment, the lignin composition of the present invention is extracted from exploded palm empty fruit bunches (EFBs) using a solvent. The explosion treatment can be carried out, for example, by exposing the palm empty fruit bunches to saturated steam at 220 to 230°C under pressure in a pressure vessel for 20 minutes, followed by rapid release into the atmosphere. The explanation for the solvent (extraction solvent) is as described for the first embodiment. During extraction, it is preferable to heat and pressurize the exploded palm empty fruit bunches while immersed in the solvent for a predetermined period of time. The heating temperature is preferably 230 to 250°C. The pressure is preferably 2.0 to 2.4 MPa. The heating and pressurization time is preferably 1 to 3 hours. During extraction, a pressure vessel capable of stirring the exploded palm empty fruit bunches and the solvent can be used.

[0045] In the first and second embodiments described above, the extracted lignin composition may be purified as necessary. An example of purification will be described below.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] By the method according to the first or second embodiment described above, of the lignin content contained in the lignin-containing raw material (for example, acid-treated woody biomass or exploded palm empty fruit bunches), 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.

[0052] 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.

[0053] [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. The thermosetting resin composition of this embodiment exhibits excellent mechanical properties and excellent fluidity.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] (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.

[0059] 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.

[0060] (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.

[0061] (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.

[0062] 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.

[0063] (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.

[0064] 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.

[0065] [Rubber Composition] A rubber composition according to one aspect of the present invention includes the lignin composition of the present invention described above and a rubber material. The rubber composition of this aspect exhibits excellent mechanical properties and excellent flowability.

[0066] 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.

[0067] 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.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] 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.

[0072] Examples of the present invention will be described below, but the present invention is not limited to these examples.

[0073] [Preparation of Lignin Composition] Example 1 (1) Extraction Step 100 parts by mass (parts by mass as lignin) of acid-treated woody biomass (lignin content: 42% by mass), 245 parts by mass of phenol, and 27 parts by mass of water were placed in a pressure-resistant vessel capable of stirring, and heated and stirred at 1.7 MPa and 220°C for 2 hours.

[0074] (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.

[0075] (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.

[0076] (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 (100 to 150°C) to remove the phenol, thereby obtaining a lignin composition.

[0077] Example 2 A lignin composition was obtained in the same manner as in Example 1, except that the pressure was 1.1 MPa and the temperature was 200°C in the extraction step.

[0078] Example 3 A lignin composition was obtained in the same manner as in Example 1, except that the pressure was 0.7 MPa and the temperature was 180°C in the extraction step.

[0079] Example 4 A lignin composition was obtained in the same manner as in Example 1, except that the pressure was 0.5 MPa and the temperature was 120°C in the extraction step.

[0080] Example 5 A lignin composition was obtained in the same manner as in Example 1, except that 100 parts by mass (parts by mass as lignin) of exploded palm empty fruit bunches (lignin content: 41% by mass), 245 parts by mass of phenol, and 27 parts by mass of water were placed in a stirrable pressure-resistant vessel and heated and stirred at 2.2 MPa and 240°C for 2 hours.

[0081] Comparative Example 1 100 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 stirrable pressure vessel and heated and stirred at 0.8 MPa and 220°C for 2 hours. The obtained extract was subjected to the same purification process as in Example 1 to obtain a lignin composition.

[0082] Comparative Example 2 A lignin composition was obtained in the same manner as in Comparative Example 1, except that the amount of phenol was 55 parts by mass, water was 27 parts by mass, and ethanol was 190 parts by mass, the extraction pressure was 2.8 MPa, and the extraction time was 2 hours.

[0083] Comparative Example 3: 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. Then, cellulose-containing solids were removed by filtration (No. 2 filter paper). The aqueous layer was separated from the obtained filtrate, and the 1-butanol layer was extracted. The extracted 1-butanol layer was concentrated and dried to obtain a lignin composition.

[0084] Comparative Example 4 Kraft lignin (Lignin, alkaline (product number 370959) manufactured by SIGMA-ALDRICH) was used as the lignin composition (lignin).

[0085] [Analysis of Lignin Compositions] The lignin compositions of Examples 1 to 5 and Comparative Examples 1 to 4 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. 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)" consisting of two "TSKgel GMHXL (manufactured by Tosoh Corporation)" organic general-purpose columns packed with a styrene-based polymer filler and a "G2000HXL (manufactured by Tosoh Corporation)" connected in series. The sample was developed at 40°C with tetrahydrofuran as an eluent 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)).

[0086] The following items (a) to (d) were determined from the molecular weight chart of the sample determined by GPC. (a) Molecular weight at the maximum differential distribution value In the molecular weight chart of the sample determined by GPC (plotted with dw / dLogM on the y-axis and LogM on the x-axis), the molecular weight LogM value at which the differential distribution value (dw / dLogM) is maximum in the molecular weight LogM range of 2.40 to 2.60 was designated the "molecular weight LogM 2.40-2.60 peak." Furthermore, this "maximum value" was designated the "differential distribution value (dw / dLogM) maximum value (di)." Furthermore, in the molecular weight LogM range of 2.60 to 2.75 in the same chart, the molecular weight LogM value at which the differential distribution value (dw / dLogM) is maximum was designated the "molecular weight LogM 2.60-2.75 peak." The "maximum value" was defined as the "maximum value (tri) of the differential distribution value (dw / dLogM)." As an example, a molecular weight chart obtained for Example 1 (with dw / dLogM plotted on the y-axis and LogM plotted on the x-axis) is shown in Figure 1.

[0087] (b) Integral distribution values ​​(%) at molecular weights Log M2.40, Log M2.55, Log M2.64, and Log M2.73 In a chart of the molecular weight of the sample determined by GPC (y-axis is integral distribution value (%), x-axis is plotted with Log M), the integral distribution values ​​(%) were determined at molecular weights Log M2.40, Log M2.55, Log M2.64, and Log M2.73.

[0088] (c) Integral distribution value (%) 2.55-2.40 The difference obtained by subtracting the integral distribution value (%) of a molecular weight Log M 2.40 from the integral distribution value (%) of a molecular weight Log M 2.55 was taken as the "integral distribution value (%) 2.55-2.40."

[0089] (d) Integral distribution value (%) 2.73-2.55 The difference obtained by subtracting the integral distribution value (%) of a molecular weight Log M 2.55 from the integral distribution value (%) of a molecular weight Log M 2.73 was taken as the "integral distribution value (%) 2.73-2.55."

[0090] (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.

[0091] (3) Phenol Trimer Content The phenol trimer content 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" 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 (A) and acetonitrile (B) was used as the mobile phase. The phenol trimer 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 phenol trimer components were ionized by electrospray ionization and then measured using a negative-mode quadrupole time-of-flight mass spectrometer over a mass-to-charge ratio range of 50 to 1000. Assuming that all compounds were detected in their deprotonated form, the structures of the phenol trimers contained in the sample were identified as compounds (a) to (e) based on their mass-to-charge ratios. 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 trimer components in the sample was calculated from a calibration curve of a separately prepared standard 2,2'-dihydroxydiphenylmethane solution.

[0092] (4) Content of the Compound Represented by Formula (2) The content of the compound represented by formula (2) was measured using liquid chromatography-mass spectrometry (LC / MS). Specifically, the dimer components (a group of compounds containing two phenol residues) were separated using the same gradient method as in "(3) Content of Phenol Trimer" above. The obtained dimer components were ionized by electrospray, and then measured using a negative-mode quadrupole-time-of-flight mass spectrometer over a mass-to-charge ratio range of 50 to 1000. The peak area of ​​compound (2) contained in the sample was calculated from the mass-to-charge ratio. The content of compound (2) in the sample was calculated from a calibration curve of a standard 2,2'-dihydroxydiphenylmethane solution prepared separately.

[0093] (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.

[0094] The results are shown in Table 1.

[0095]

[0096] The lignin content in Examples 1 to 5 was 85 to 86% by mass.

[0097] [Resin Composition and Molded Article] Example 6 (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 35:15. After stirring and mixing for 5 minutes at room temperature, the treated product was removed from the flask 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.) was 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 5 minutes, cooled, and pulverized to obtain a resin composition (molding material).

[0098] Example 7 A resin composition (molding material) was obtained in the same manner as in Example 6, except that the lignin composition of Example 2 was used instead of the lignin composition of Example 1.

[0099] Example 8 A resin composition (molding material) was obtained in the same manner as in Example 6, except that the lignin composition of Example 3 was used instead of the lignin composition of Example 1.

[0100] Example 9 A resin composition (molding material) was obtained in the same manner as in Example 6, except that the lignin composition of Example 4 was used instead of the lignin composition of Example 1.

[0101] Example 10 A resin composition (molding material) was obtained in the same manner as in Example 6, except that the lignin composition of Example 5 was used instead of the lignin composition of Example 1.

[0102] Comparative Example 5 A resin composition (molding material) was obtained in the same manner as in Example 6, except that the lignin composition of Comparative Example 1 was used instead of the lignin composition of Example 1.

[0103] Comparative Example 6 A resin composition (molding material) was obtained in the same manner as in Example 6, except that the lignin composition of Comparative Example 2 was used instead of the lignin composition of Example 1.

[0104] Comparative Example 7 A resin composition (molding material) was obtained in the same manner as in Example 6, except that the lignin composition of Comparative Example 3 was used instead of the lignin composition of Example 1.

[0105] Comparative Example 8 A resin composition (molding material) was obtained in the same manner as in Example 6, except that the lignin composition of Comparative Example 4 was used instead of the lignin composition of Example 1.

[0106] Blank A resin composition (molding material) was obtained in the same manner as in Example 6, except that the use of the lignin composition of Example 1 was omitted.

[0107] (2) Evaluation of Resin Composition Flowability (Spiral Flow) The resin compositions obtained in the blank, Examples 6 to 10, and Comparative Examples 5 to 8 were each compressed at room temperature at 15 tf to produce tablets. The tablets were preheated in a hot air circulating oven at 90°C for 10 minutes and then placed in a transfer molding machine (MF-O15, manufactured by Marushichi Co., Ltd.). The tablets were molded in a spiral flow mold under conditions of 165°C, 40 MPa, and 5 minutes, and the length over which the resin composition flowed (spiral flow) was measured. The spiral flow ratio (%) in Examples 6 to 10 and Comparative Examples 5 to 8 was calculated, assuming the spiral flow in the blank to be 100%.

[0108] (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 circulating 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 5 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.

[0109] (4) Evaluation of Physical Properties of Molded Articles The flexural strength and flexural modulus of the molded articles (test pieces) obtained in (3) above were measured 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 and with a load applied at a support distance of 64 mm. The percentages (%) of the flexural strength of Examples 6 to 10 and Comparative Examples 5 to 8 were calculated when the flexural strength of the blank was taken as 100%. In addition, the percentages (%) of the flexural modulus of the blank was calculated when the flexural modulus of the blank was taken as 100%.

[0110] The results are shown in Table 2.

[0111]

[0112] As shown in Table 2, the thermosetting resin compositions of Examples 6 to 10 not only had improved mechanical properties (bending strength and bending modulus) compared to the blank, but also had significantly higher spiral flow (fluidity) compared to Comparative Examples 5 to 8. This indicates that a lignin composition containing two or more compounds represented by formula (1) above, with a total content of the compounds of 0.05% by mass or more, can significantly suppress a decrease in fluidity when added to a thermosetting resin. Furthermore, it was confirmed that the thermosetting resin compositions of Examples 6 to 10 could improve the surface smoothness (smoothness) of the molded body compared to Comparative Examples 5 to 8.

[0113] 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 0.50 mass% or more: (In formula (1), R ａ R represents a trivalent saturated hydrocarbon group having 1 to 3 carbon atoms. ａ The single bonds *, **, and *** in the formula (I) are each bonded to any of the carbon atoms constituting the corresponding benzene ring. １１ ~R １５ One of them is R ａ R is a single bond that bonds to ２１ ~R ２５ One of them is R ａ R is a single bond that bonds to ３１ ~R ３５ One of them is R ａ R is a single bond that bonds to ａ R is not a single bond that bonds to １１ ~R １５ , R ２１ ~R ２５ and R ３１ ~R ３５ each represents a hydrogen atom, a methoxy group, a hydroxy group, a furyl group, a hydroxymethylfuryl group, a hydroxyphenyl group, a hydroxymethoxyphenol group, or a hydroxydimethoxyphenol group.

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 1.0 to 4.

0.

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 0.50 to 5.00 mass%.

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 difference in integral distribution value (%) at molecular weights LogM 2.55 and 2.73 of the lignin composition is 15 or more and 25 or less, as measured by gel permeation chromatography (GPC).

9. A lignin composition, having a maximum peak value of a differential distribution value (dw / dLogM) present at a molecular weight LogM of 2.60 to 2.75 of the lignin composition, which is 80 or more and 250 or less, as measured by gel permeation chromatography (GPC).

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

11. The thermosetting resin composition according to claim 10, wherein the thermosetting resin comprises at least one selected from the group consisting of 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. Use of the lignin composition according to any one of claims 1 to 9 for promoting a crosslinking reaction in a thermosetting resin molding material containing a thermosetting resin.

13. The use of the lignin composition of claim 12, wherein the thermosetting resin comprises one or more 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.

14. 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 9.

15. A modifier for thermosetting resins or a crosslinking reaction accelerator for thermosetting resins, comprising the lignin composition according to any one of claims 1 to 9.

16. A rubber composition comprising the lignin composition according to any one of claims 1 to 9 and a rubber material.

17. A molded article obtained by curing the thermosetting resin composition according to claim 10 or the rubber composition according to claim 16.

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