JP2018178023A - Method for producing lignin-derived epoxy resin, lignin-derived epoxy resin, epoxy resin composition and cured product thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for efficiently producing an epoxy resin from lignin obtained by applying high-temperature heating to woody biomass in the presence of a base, a lignin-derived epoxy resin synthesized by the production method, an epoxy resin composition and a cured product thereof.SOLUTION: The present invention provides a method for producing an epoxy resin that is obtained by the reaction of lignin obtained by applying heating to woody biomass in the presence of a base, with epihalohydrin. In the method, during the reaction, added is a solvent with a Hildebrand solubility parameter (SP value) of 17.9-26.5 MPa.SELECTED DRAWING: None

Description

  The present invention relates to a method for producing an epoxy resin derived from lignin, an epoxy resin derived from lignin, an epoxy resin composition using the same, and a cured product thereof.

  BACKGROUND ART In recent years, biomass (renewable organic resources obtained from animals and plants) has attracted attention as carbon-neutral resources from the viewpoint of environmental problems. For example, production of bioethanol using an edible biomass which can be a food such as a sugar raw material or a starch raw material is mentioned, but in this case, competition with food is a problem. On the other hand, non-edible biomass is expected to be used as an industrial raw material because there is no competition with food. A representative example of lignocellulosic biomass, which is one of non-edible biomass, is woody biomass such as conifers and broad-leaved trees, and the development of chemical products using them as raw materials is more difficult than conventional petroleum-derived chemical product development Although it has a high degree of social demand, it is a field that is actively researched and developed for practical use.

  Lignocellulosic biomass is composed of cellulose, hemicellulose and lignin. Among them, lignin plays a role of adhesion molecule to connect cellulose, and is a compound in which phenylpropane skeleton is randomly polymerized, and has a very complicated structure. The detailed structural analysis has not been achieved yet, as the molecular weight is usually a macromolecule having a molecular weight of over 10,000. Therefore, the use of lignin as a raw material for chemical products is very difficult, and until now it has been limited to the use as fuel and dispersant.

  However, in response to recent social backgrounds, lignin is rich in aromatic compounds in its structure, and as a new resource, its use as a chemical industry product such as resin is being sought. As one of them, since lignin contains phenolic hydroxyl groups, it is expected as a resin raw material such as phenol resin. In addition, lignin-derived epoxy resins in which glycidyl groups are inserted into phenolic hydroxyl groups are also candidates for application. However, since lignin as a raw material is a mixture of complicated structures as described above, the synthesis method of epoxy resin derived from lignin does not proceed efficiently when glycidylation proceeds even using the same method as petroleum-derived phenols At present, the situation is that it is a major obstacle to commercialization.

  For example, Patent Document 1 discloses that solvolysis is promoted using a mineral acid under the condition in which alkali lignin and petroleum-derived phenol are mixed, and then it is reacted with epichlorohydrin. A process for producing the resulting lignin-epoxy resin adhesive has been reported. However, in the lignin-derived epoxy resin synthesized by this method, since the petroleum-derived phenol is used in combination, the biomass ratio of the product is low, and the value as a carbon-neutral resource must be low. In addition, the lignin-derived epoxy resin disclosed in the present method is unclear to what extent the lignin is glycidylated, and can not be said to be an efficient epoxidation method.

Moreover, the example which epoxidized the lignin derived from a gramineous plant is reported by patent documents 2 and 3. However, lignin of gramineous plants has a low throughput, particularly in Japan, and it is difficult to procure a large amount of raw materials. In addition, while epoxy resins derived from graminaceous plant lignin are easier to synthesize than epoxy resins derived from lignin contained in woody biomass such as conifers and broad-leaved trees, they tend to have inferior resin properties such as heat resistance of cured products. It is in.
Patent Document 4 describes a production method in which an epoxy compound is synthesized using epichlorohydrin after dissolving biomass-derived lignin in an alkaline aqueous solution. However, epoxidation in a large excess of an aqueous alkali solution as in the present method makes it difficult to control the reaction and often makes industrialization difficult. In addition, the side reaction between the epichlorohydrin used in excess and the base may cause deterioration of the quality of the product or deterioration of the recovered epichlorohydrin.

Patent Documents 5, 6, and 7 describe the epoxidation of a compound (lignophenol) in which petroleum-derived phenol is added to lignin. However, these materials require a modification step using a large amount of acid and are products of relatively high environmental load because the biomass ratio of the product is reduced by the amount of addition of phenol.
Further, Patent Documents 8 and 9 etc. are epoxidized products using lignin obtained by steam explosion method as raw materials, Patent Documents 10, 11 and 12 etc. are obtained by processing woody biomass under high temperature and high pressure conditions There is a report on epoxidized products made from lignin. However, these lignins are expensive in processing lignin and require high initial equipment investment, so the hurdle for practical use is high.

  As described above, although epoxy resins derived from lignin have been actively studied, they are derived from woody biomass, and epoxy resins derived from lignin that can be produced using existing equipment used in papermaking processes etc. Epoxidation method has not been established, and establishment of a synthesis process has been strongly required for the practical use of epoxy resins derived from lignin.

Japanese Patent Application Laid-Open No. 5-4429 JP 2011-144340 A JP, 2012-236811, A Patent No. 5072822 gazette Patent No. 4015035 JP, 2009-263549, A JP 2011-99083 A Patent No. 4561242 gazette JP, 2005-199209, A JP, 2009-084320, A JP, 2012-201645, A JP, 2012-201828, A

  An object of the present invention is to provide a method for efficiently producing an epoxy resin of lignin obtained by heat-treating woody biomass in the presence of a base, and an epoxy resin derived from lignin synthesized by the method.

The present invention relates to the epoxy resin described below.
[1] A method for producing an epoxy resin obtained by reacting lignin obtained by heat-treating woody biomass in the presence of a base and an epihalohydrin, wherein Hildebrand's solubility parameter (SP value) is 17.9 to 26 at the time of reaction. A method for producing an epoxy resin comprising adding a solvent in the range of 5 MPa ^1/2 .
[2] The method for producing an epoxy resin according to the above [1], wherein the woody biomass is a broadleaf tree.
[3] The method for producing an epoxy resin according to [1] or [2], wherein the lignin is soda anthraquinone lignin or kraft lignin.
[4] The method for producing an epoxy resin according to any one of the above [1] to [3], wherein the lignin is a lignin purified by extraction with a solvent.
[5] The method for producing an epoxy resin according to any one of [1] to [4], wherein the amount of the solvent added is in the range of 15 to 100% by weight with respect to the epihalohydrin.
[6] The method for producing an epoxy resin according to any one of the above-mentioned [1] to [5], wherein the solvent is an alcohol or a ketone.
[7] The method for producing an epoxy resin according to any one of the above [1] to [6], wherein the solvent is an alcohol having 3 or less carbon atoms or a ketone having 4 or less carbon atoms.
[8] The method for producing an epoxy resin according to any one of the above [1] to [7], wherein a quaternary ammonium salt is further added as a catalyst.
[9] An epoxy resin synthesized by the method for producing an epoxy resin according to any one of [1] to [7].
[10] An epoxy resin composition comprising the epoxy resin according to the preceding paragraph [9] and a curing agent and / or a curing accelerator.
[11] A cured product obtained by curing the epoxy resin composition according to the previous item [10].

  In the present invention, a method for efficiently converting lignin obtained by relatively easy treatment of woody biomass to an epoxy resin is disclosed, so a highly functional lignin-derived epoxy resin can be obtained at low cost. Can. In addition, a resin composition, a prepreg, a cured product or the like using the epoxy resin can be provided. Therefore, it can contribute to the practical use of lignin-derived materials, which were previously unutilized resources, and can provide chemical products with characteristics different from conventional petroleum-derived compounds to society, and also has effects such as suppression of carbon dioxide emissions Can also be expected.

The method for producing an epoxy resin derived from lignin according to the present invention is the solubility of Hildebrand at the time of reaction in the method for producing an epoxy resin obtained by reacting lignin obtained by treating woody biomass with heating and high temperature treatment in the presence of a base and epihalohydrin. The method is characterized in that a solvent having a parameter (SP value) in the range of 17.9 to 26.5 MPa ^1/2 is added.

  The woody biomass in the present invention means woody lignocellulose, and indicates so-called common trees and woods. Lignocellulosic lignocelluloses are classified into conifers that are gymnosperms and broad-leaved trees that are angiosperms. Specifically, conifers such as pines, cedars, cypresses, makis and yews, eucalyptus, beech, willow, acacias, and Douglass Examples include hardwoods such as fur and radiata pine. These woody biomass may use a single tree as a raw material, or as long as they are trees of the same classification, a combination of two or more types may be used as a raw material. Moreover, a broadleaf tree is more preferably used for the woody biomass used by this invention.

  As lignin which is a raw material of the present invention, lignin which is separated by subjecting the woody biomass to a high temperature treatment in the presence of a base is used. For example, wood flour and wood chips are added to a base such as an aqueous solution of sodium hydroxide, and after adding necessary additives, they are treated at a high temperature of 100 ° C. to 200 ° C., except for pulp remaining as solids. The obtained black liquor can be neutralized with an acid such as sulfuric acid or so-called lignoboost treatment in which carbon dioxide gas is blown to obtain raw material lignin. Specifically, lignin obtained through treatments such as alkaline digestion, soda anthraquinone digestion (soda AQ digestion), kraft digestion, alkaline oxygen digestion, alkaline hydrogen peroxide digestion and the like can be mentioned, and any of them can be used, In the present invention, alkali digestion, soda anthraquinone digestion, alkali lignin obtained from kraft digestion, soda anthraquinone lignin (soda AQ lignin), kraft lignin and the like are more preferably used, and soda anthraquinone lignin and kraft lignin are particularly preferably used. In addition, alkali lignin, soda anthraquinone lignin, kraft lignin, etc. can be produced at existing paper mill equipment, so they are considered to be able to be digested at a lower cost compared to other cooking methods, and even from an economic point of view , A preferred lignin.

  The lignin, which is the raw material of the present invention, may be pretreated or purified as necessary, and converted to lignin having more preferable properties as a resin raw material. Examples of pretreatment and purification include fractionation of preferred components, reduction in molecular weight, solvent extraction, recrystallization, reprecipitation, chemical modification, etc., but high-purity lignin can be obtained at low cost with high yield. Purification by solvent extraction is mentioned as a preferred example.

  When lignin, which is a raw material of the present invention, is extracted and purified with a solvent or the like, lignin of the raw material is dissolved in a solvent, and purification is performed by removing insolubles by an operation such as filtration. There is no particular limitation on the solvent to be used, but solvents having low solubility of sugar and impurities, high molecular weight lignin and high extraction ratio of low to medium molecular weight lignin are preferable. Specifically, alcoholic solvents such as methanol, ethanol, propanol and ethylene glycol, ketone solvents such as acetone, methyl ethyl ketone and acetylacetone, ether solvents such as tetrahydrofuran, dioxane, diethyl ether and dimethoxyethane, methyl acetate, ethyl acetate Ester solvents such as methyl formate and ethyl formate, halogen-containing solvents such as dichloromethane, chloroform and epichlorohydrin, aprotic high polar solvents such as dimethyl sulfoxide, dimethylformamide, dimethylacetamide and methyl pyrrolidone, water, etc. Among them, alcoholic solvents such as methanol, ethanol, propanol, ethylene glycol and the like, acetone, methyl ethyl ketone, acetyl acetone, etc. Emissions based solvents, mentioned as preferred examples include methanol, ethanol, isopropanol, acetone, methyl ethyl ketone particularly preferred. As these solvents, only a single solvent may be used, or two or more solvents may be used in combination. The amount of solvent used is usually 0.1 times to 50 times, preferably 0.5 times to 20 times, and more preferably 1 time to 10 times the weight of lignin. . In addition, lignin after extraction may be used as a raw material of lignin that has been dried by distilling off the solvent as a raw material, or may be used as a raw material of the reaction as it is in a lignin solution.

  As epihalohydrin used in the reaction for obtaining the epoxy resin of the present invention, epichlorohydrin, α-methylepichlorohydrin, β-methylepichlorohydrin, epibromohydrin and the like are preferably mentioned, and in particular, epichlorohydrin which is industrially easily available is preferable. The amount of epihalohydrin to be used is generally 2 to 100 moles, preferably 2 to 40 moles, more preferably 2 to 20 moles, in view of economics, with respect to 1 mole of the hydroxyl group of the bisphenol compound of the present invention.

In the method for producing a lignin-derived epoxy resin of the present invention, a solvent having a Hildebrand solubility parameter (SP value) in the range of 17.9 to 26.5 MPa ^1/2 is added at the time of reaction. Hildebrand's solubility parameter δ is a parameter defined by the following equation (1) from molar heat of vaporization ΔH and molar volume V, gas constant R and absolute temperature T.
δ = {(ΔH-RT) / V} ^1/2 equation (1)
In addition, Hildebrand's solubility parameter δ is a parameter related to the dispersion force of Hansen's solubility parameter (δ _d ), a parameter related to interdipolar force (δ _p ), a parameter of hydrogen bonding force (δ _h ), and the following equation (2) It is known that there is a relationship of).
δ = (δ _d ² + δ _p ² + δ _h ² ) ^1/2 equation (2)
In the present patent, as the Hildebrand solubility parameter (SP value), a value calculated using the above equation (2) is used unless otherwise specified. The parameters of the dispersion force of each solvent (δ _d ), the parameters of interdipole force (δ _p ), and the parameters of hydrogen bonding force (δ _h ), which are necessary at that time, are HANAEN SOLUBILITY PARAMETERS A USER'S The values described in HANDBOOK (Charls M. Hansen, CRC Press, 2000) were used.

In the production method of the present invention, the molecular chain of lignin is broken by adding a solvent having a Hildebrand solubility parameter (SP value) in the range of 17.9 to 26.5 MPa ^1/2 , and an internal phenolic It is considered that there is an effect to advance the glycidylation reaction to the hydroxyl group. This effect is a peculiar phenomenon of lignin having a complicated molecular chain, and the same effect is not observed in the epoxidation of a conventional petroleum-derived and synthesized phenolic compound.

The solvent to be added is not particularly limited as long as it has a Hildebrand solubility parameter (SP value) in the range of 17.9 to 26.5 MPa ^1/2 , and examples thereof include ethanol, dipropylene glycol, γ-butyrolactone, 1,6-Hexanediol, N, N-dimethylformamide, isopropanol, ethylene glycol monomethyl ether, butanol, N-methyl pyrrolidone, cyclohexanone, acetylacetone, glycerol triacetate, diethylene glycol monoethyl ether acetate, methyl ethyl ketone, ethyl acetate, dioxane, diethylene glycol dimethyl ether Etc., preferably ethanol, isopropanol, dipropylene glycol, hexanediol, ethylene glycol monomethyl ether And solvents such as alcohols such as methyl ethyl ketone, acetylacetone and cyclohexanone, and ethers such as dioxane and diethylene glycol dimethyl ether, more preferably alcohols such as ethanol, isopropanol, dipropylene glycol, hexanediol and ethylene glycol monomethyl ether And solvents such as ketones such as methyl ethyl ketone, acetylacetone and cyclohexanone, and more preferably solvents such as alcohols having 3 or less carbon atoms such as ethanol, isopropanol and dipropylene glycol, and ketones having 4 or less carbon atoms such as methyl ethyl ketone It is. As these solvents, only a single solvent may be used, or two or more solvents may be used in combination. The amount of solvent used is usually 0.1 to 50 times, preferably 0.15 to 10 times, more preferably 0.15 to 5 times the weight of epichlorohydrin, particularly preferably The amount is 0.15 to 1 time.

  In general, an epoxy resin is obtained by a reaction of adding a phenol compound and an epihalohydrin in the presence of an alkali metal hydroxide or a catalyst and then closing and epoxidizing a formed 1,2-halohydrin ether group. As an alkali metal hydroxide which can be used for an epoxidation reaction, sodium hydroxide, potassium hydroxide etc. are mentioned preferably, These may use a solid substance as it is, or may use its aqueous solution. When an aqueous solution is used, an aqueous solution of the alkali metal hydroxide is continuously added to the reaction system, and liquid separation from a mixture of water and epihalohydrin continuously distilled off under reduced pressure or under normal pressure is used. Water may be removed and only epihalohydrin may be continuously returned to the reaction system. The amount of the alkali metal hydroxide used is usually 0.9 to 3.0 mol, preferably 1.0 to 2.5 mol, more preferably 1. per mol of hydroxyl group such as a phenol compound. It is 0 to 2.0 mol, particularly preferably 1.1 to 1.7 mol. Moreover, in the epoxidation reaction, it is possible to significantly reduce the amount of halogen contained in the obtained epoxy resin by using sodium hydroxide in the form of flakes, rather than using sodium hydroxide as an aqueous solution. Further, it is preferable that the flaky sodium hydroxide be separately added to the reaction system. By performing the split addition, it is possible to prevent the rapid rise of the reaction temperature, and thereby to prevent the formation of the impurity 1,3-halohydrin or halomethylene.

  A catalyst can be used to promote the epoxidation reaction. As a catalyst which can be used, tetramethyl ammonium chloride, tetramethyl ammonium bromide, tetramethyl ammonium iodide, tetraethyl ammonium chloride, tetraethyl ammonium bromide, tetraethyl ammonium iodide, tetrapropyl ammonium chloride, tetrapropyl ammonium bromide, tetrapropyl ammonium Preferred examples include quaternary ammonium salts such as iodide and trimethylbenzylammonium chloride, and inorganic salts such as sodium chloride, sodium bromide, sodium iodide, sodium iodide, potassium chloride, potassium bromide and potassium iodide, and tetramethylammonium chloride. , Tetramethyl ammonium bromide, tetramethyl ammonium iodide, tetraethyl ammonium chloride , Tetraethyl ammonium bromide, tetraethyl ammonium iodide, sodium iodide, more preferably potassium iodide, tetramethylammonium iodide, tetraethylammonium chloride, tetraethylammonium bromide, tetraethylammonium iodide particularly preferred. As these catalysts, only a single catalyst may be used, or two or more types of catalysts may be used in combination. The amount of quaternary ammonium salt used is usually 0.1 to 15 g, preferably 0.2 to 10 g, per 1 mol of the hydroxyl group of the raw material.

  The reaction temperature is usually 30 to 95 ° C, preferably 35 to 90 ° C. The reaction time is usually 0.5 to 10 hours, preferably 1 to 8 hours. After completion of the reaction, the reaction product is washed with water or without heating, and the epihalohydrin, the solvent and the like are removed from the reaction solution under heating and reduced pressure. In order to further reduce the amount of halogen contained in the obtained epoxy resin, the recovered epoxy resin is dissolved in a solvent such as toluene or methyl isobutyl ketone, and an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide The reaction can also be carried out by adding an aqueous solution of (III) to ensure ring closure. In this case, the amount of the alkali metal hydroxide used is usually 0.01 to 0.3 mol, preferably 0.05 to 0.2 mol, per 1 mol of the raw material hydroxyl group. The reaction temperature is usually 50 to 120 ° C., and the reaction time is usually 0.5 to 2 hours.

  After completion of the reaction, the salt formed is removed by filtration, water washing and the like, and the solvent is distilled off under heating and reduced pressure to obtain the epoxy resin of the present invention. When the epoxy resin of the present invention precipitates as crystals, the salt of the epoxy resin of the present invention may be filtered after dissolving the salt formed in a large amount of water.

  The epoxy resin obtained by the method for producing an epoxy resin of the present invention is very difficult to determine its structure because it uses lignin whose structure can not be specified. Since the resulting epoxy resin is a mixture of extremely complex structures, broad signals derived from glycidyl groups, methoxy groups and some aromatic groups and aliphatic substituents can be obtained using analytical methods such as NMR. It can only be obtained and the compound can not be determined at all. However, as described above, since a broad peak derived from a glycidyl group can be observed, the presence or absence of the progress of epoxidation can be determined.

  The epoxy equivalent of the epoxy resin of the present invention is 150 to 400 g / eq. Preferably 200 to 380 g / eq. It is more preferable that it is 250-360 g / eq. Is particularly preferred. When the epoxy equivalent is in the above range, it is possible to obtain an epoxy resin excellent in the heat resistance, electric reliability and water absorption of the cured product. Epoxy equivalent is 400 g / eq. Is not preferable because the epoxy ring is not completely closed and it is expected that a large amount of a compound having no functional group is contained. In addition, many of these compounds which did not close their rings often contain chlorine in many cases, and are preferably used for electronic materials since there is concern over the release of chlorine ions under high temperature and humidity conditions and the corrosion of wiring due to them. Absent.

  The total chlorine remaining in the epoxy resin is preferably 5000 ppm or less, more preferably 3000 ppm or less, and particularly preferably 2000 ppm or less. The adverse effects of the amount of chlorine are the same as described above.

  The epoxy resin of the present invention has a resinous form having a softening point. Here, as a softening point, 55-250 degreeC is preferable, and it is especially preferable that it is 60-200 degreeC. If the softening point is too low, blocking during storage may become a problem, and there is a risk that handling must be performed at a low temperature. On the other hand, if the softening point is too high, problems such as poor handling may occur when kneading with other resins.

  Hereinafter, the epoxy resin composition of the present invention will be described. The epoxy resin composition of the present invention contains the epoxy resin of the present invention as an essential component. In the epoxy resin composition of the present invention, the epoxy resin of the present invention may be used alone or in combination with other epoxy resin.

  Specific examples of other epoxy resins which can be used in combination include bisphenols (bisphenol A, bisphenol F, bisphenol S, biphenol, bisphenol AD and bisphenol I) and phenols (phenol, alkyl substituted phenol, aromatic substituted phenol, naphthol, etc.) Alkyl substituted naphthol, dihydroxy benzene, alkyl substituted dihydroxy benzene and dihydroxy naphthalene, etc. and various aldehydes (formaldehyde, acetaldehyde, alkyl aldehyde, benzaldehyde, alkyl substituted benzaldehyde, hydroxy benzaldehyde, naphthaldehyde, glutaraldehyde, phthalaldehyde, crotonaldehyde and cinnamaldehyde Etc.), aromatic compounds such as xylene and Polycondensates of hydrido polycondensates with phenols, phenols and various diene compounds (dicyclopentadiene, terpenes, vinylcyclohexene, norbornadiene, vinyl norbornene, tetrahydroindene, divinyl benzene, divinyl biphenyl, diisopropenyl biphenyl, Polymers with butadiene and isoprene), polycondensates of phenols with ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, acetophenone, benzophenone etc.), phenols and aromatic dimethanols (benzene dimethanol and biphenyl di) Polycondensates with methanol etc.), Polycondensates with phenols and aromatic dichloromethyls (α, α'-dichloroxylene and bischloromethylbiphenyl etc), phenols and aromatic bis alcohol Polycondensates of sylmethyls (such as bismethoxymethylbenzene, bismethoxymethylbiphenyl and bisphenoxymethylbiphenyl), polycondensates of bisphenols and various aldehydes, and glycidyl ether epoxy resins obtained by glycidylating alcohols and the like, fats Although cyclic epoxy resin, glycidyl amine type epoxy resin, glycidyl ester type epoxy resin etc. are mentioned, if it is an epoxy resin usually used, it will not be limited to these. These may be used alone or in combination of two or more.

  When another epoxy resin is used in combination, the proportion of the epoxy resin of the present invention to the total epoxy resin component in the epoxy resin composition of the present invention is preferably 10% by mass, more preferably 20% by mass or more, and 30% by mass. The above is more preferable. However, when using the epoxy resin of this invention as a modifier of an epoxy resin composition, it adds in the ratio used as 1-30 mass% in all the epoxy resins.

In the epoxy resin composition of the present invention, a curing agent may be added if necessary. As a specific example of a hardening | curing agent, an amine compound, an acid anhydride type compound, an amide type compound, a phenol type compound etc. are mentioned, for example. Specific examples of these other curing agents are shown in the following (a) to (e).
(A) Amine compounds Diaminodiphenylmethane, diethylenetriamine, triethylenetetramine, diethylenediphenylsulfone, isophoronediamine, naphthalenediamine, etc. (b) Acid anhydride-based compounds Phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, maleic anhydride Tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methyl nadic anhydride, hexahydrophthalic anhydride and methyl hexahydrophthalic anhydride (c) amide compounds, dicyandiamide, or a dimer of linolenic acid and ethylenediamine synthesized Polyamide resin etc.,

(D) Phenolic compounds Polyphenols (bisphenol A, bisphenol F, bisphenol S, fluorene bisphenol, terpene diphenol, 4,4'-dihydroxybiphenyl, 2,2'-dihydroxybiphenyl, 3,3 ', 5, 5'-Tetramethyl- (1,1'-biphenyl) -4,4'-diol, hydroquinone, resorcinol, naphthalenediol, tris- (4-hydroxyphenyl) methane and 1,1,2,2-tetrakis (4 -Hydroxyphenyl) ethane and the like); phenols (eg, phenol, alkyl-substituted phenol, naphthol, alkyl-substituted naphthol, dihydroxybenzene and dihydroxynaphthalene), and aldehydes (formaldehyde, acetaldehyde, benzaldehyde, p-hydro Phenolic resins obtained by condensation with cibenzaldehyde, o-hydroxybenzaldehyde and furfural etc., ketones (p-hydroxyacetophenone and o-hydroxyacetophenone etc), or dienes (dicyclopentadiene and tricyclopentadiene etc); Phenols and substituted biphenyls (4,4′-bis (chloromethyl) -1,1′-biphenyl and 4,4′-bis (methoxymethyl) -1,1′-biphenyl etc.) or substituted phenyls Phenolic resins obtained by polycondensation with 1,4-bis (chloromethyl) benzene, 1,4-bis (methoxymethyl) benzene, 1,4-bis (hydroxymethyl) benzene etc .; the above-mentioned phenols and / or Or a modified product of the aforementioned phenolic resin; Lumpur A and halogenated phenols such as brominated phenol resin (e) Other imidazoles, BF3-amine complex, guanidine derivatives

  Among these curing agents, activities such as amine compounds such as diaminodiphenylmethane, diaminodiphenyl sulfone and naphthalenediamine, and condensates of catechol with aldehydes, ketones, dienes, substituted biphenyls or substituted phenyls, etc. A curing agent having a structure in which hydrogen groups are adjacent is preferable because it contributes to the arrangement of the epoxy resin. The curing agent may be used alone or in combination of two or more. In the epoxy resin composition of the present invention, the amount of the curing agent used is preferably 0.5 to 2 equivalents, particularly preferably 0.6 to 1.5 equivalents, per equivalent of epoxy groups of all the epoxy resins.

  If necessary, a curing accelerator may be added to the epoxy resin composition of the present invention. Specific examples of the curing accelerator include phosphines such as triphenylphosphine and bis (methoxyphenyl) phenyl phosphine, imidazoles such as 2-methylimidazole, 2-ethylimidazole, 2-ethyl, 4-methylimidazole, and the like. Tertiary amines such as-(dimethylaminomethyl) phenol, trisdimethylaminomethylphenol and diazabicycloundecene, tetrabutyl ammonium salt, triisopropyl methyl ammonium salt, trimethyl decanyl ammonium salt, cetyl trimethyl ammonium salt and the like 4 Quaternary phosphonium salts such as quaternary ammonium salts, triphenylbenzyl phosphonium salts, triphenylethyl phosphonium salts, tetrabutyl phosphonium salts (the counter ion of the quaternary salt is halogen, The organic acid ion, the hydroxide ion and the like are not particularly specified, but in particular, the organic acid ion and the hydroxide ion are preferable) and metal compounds such as tin octylate and the like. The amount of the curing accelerator used is usually 0.2 to 5 parts by mass, preferably 0.2 to 4 parts by mass, per 100 parts by mass of the epoxy resin.

  The epoxy resin composition of the present invention can optionally contain an inorganic filler. The inorganic filler contained in the epoxy resin composition of the present invention is not particularly limited as long as it is known. Specific examples of the inorganic filler include inorganic powders such as boron nitride, aluminum nitride, silicon nitride, silicon carbide, titanium nitride, zinc oxide, tungsten oxide, tungsten carbide, alumina, and magnesium oxide, and fibers such as synthetic fibers and ceramic fibers. Fillers, colorants and the like can be mentioned. The shape of the inorganic filler may be any of powder (mass, spherical), single fiber, long fiber and the like. The amount of the inorganic filler used in the epoxy resin composition of the present invention is usually 2 to 1000 parts by mass with respect to 100 parts by mass of the resin component in the epoxy resin composition. These inorganic fillers may be used alone or in combination of two or more.

  If necessary, various compounding agents such as a silane coupling agent, a mold release agent and a pigment, various thermosetting resins, various thermoplastic resins and the like can be added to the epoxy resin composition of the present invention. Specific examples of the thermosetting resin and the thermoplastic resin include vinyl ester resin, unsaturated polyester resin, maleimide resin, cyanate resin, isocyanate compound, benzoxazine compound, vinyl benzyl ether compound, polybutadiene and modified products thereof, acrylonitrile copolyester Modified products of polymers, indene resin, fluorine resin, silicone resin, polyether imide, polyether sulfone, polyphenylene ether, polyacetal, polystyrene, polyethylene, dicyclopentadiene resin and the like can be mentioned. The thermosetting resin or the thermoplastic resin is used in an amount of 60% by mass or less in the epoxy resin composition of the present invention.

  The epoxy resin composition of the present invention is obtained by uniformly mixing the above-mentioned components. The epoxy resin composition of the present invention can be easily made into a cured product by the same method as conventionally known. For example, an epoxy resin which is an essential component of the epoxy resin composition of the present invention, a curing agent, and optionally a curing accelerator, a compounding agent, various thermosetting resins, various thermoplastic resins, etc. The epoxy resin composition of the present invention obtained by sufficiently mixing until uniform using a kneader or a roll is molded by a melt casting method, a transfer molding method, an injection molding method, a compression molding method, etc. By heating for 2 to 10 hours above the melting point, a cured product of the epoxy resin composition of the present invention can be obtained.

  The epoxy resin composition of the present invention can also be a varnish containing a solvent. The varnish contains, for example, a mixture containing the epoxy resin of the present invention and a curing agent, and optionally, other components such as an inorganic filler having a thermal conductivity of 20 W / m · K or more, toluene, xylene, acetone Methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, cyclopentanone, N, N'-dimethylformamide, N, N'-dimethyl acetamide, dimethyl sulfoxide, N-methyl pyrrolidone, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, dipropylene glycol dimethyl ether , Glycol ethers such as dipropylene glycol diethyl ether, triethylene glycol dimethyl ether, triethylene glycol diethyl ether, ethyl acetate, butyl acetate, methyl cellosolve acetate Esters such as ethyl cellosolve acetate, butyl cellosolve acetate, carbitol acetate, propylene glycol monomethyl ether acetate, dialkyl glutarate, dialkyl succinate, dialkyl adipate, cyclic esters such as γ-butyrolactone, petroleum ether, petroleum naphtha, hydrogenation It can be obtained by mixing with an organic solvent such as petroleum solvents such as petroleum naphtha and solvent naphtha. The amount of the solvent is usually 10 to 95% by mass, preferably 15 to 85% by mass, based on the entire varnish. The varnish obtained as described above is impregnated into a fiber substrate such as glass fiber, carbon fiber, polyester fiber, polyamide fiber, alumina fiber and paper, and then the solvent is removed by heating, and the epoxy resin composition of the present invention The prepreg of the present invention can be obtained by bringing In addition, the "semi-hardened state" said here means the state in which the epoxy group which is a reactive functional group has remained partially unreacted. The prepreg can be hot press molded to obtain a cured product.

Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to these examples. Materials, processing contents, processing procedures, and the like described below can be appropriately changed without departing from the spirit of the present invention.
In addition, the yield of the manufactured epoxy compound was evaluated by the recovery rate defined below.
Recovery rate Recovery rate (%) = (weight of obtained epoxy resin) / (weight of raw material lignin) × 100
(The recovery rate may be 100% or more because the weight of the product increases by the amount of glycidyl group added to the raw material.)

The epoxy equivalent (some is abbreviated as "EEW") was measured under the following conditions.
・ Epoxy equivalent (EEW)
It measures by the method described in JIS K-7236, and a unit is g / eq. It is.
The glass transition point (Tg) of the cured product was measured using the following apparatus.
・ DSC
Suggested Scanning Calorimeter: DSC Q-2000 from TA-instruments

Example 1
A high temperature treatment is performed in the presence of a base according to the method described in Example 1 (1) (2) of JP-A-2016-060750 except using Eucalyptus chips and adding 0.1% by weight of anthraquinone during cooking. After making a lignin cake and drying with a hot air drier at 60 ° C., the soluble portion was extracted using 9 volumes of acetone.
7.2 parts by weight of the acetone extract of eucalyptus soda anthraquinone lignin obtained, 7.2 parts by weight of tetraethylammonium chloride, 74 parts by weight of epichlorohydrin, and 0.4 parts by weight of water are respectively added to the reaction vessel and further added as an additive solvent After adding 74 parts by weight of isopropanol, the mixture was stirred for 5 hours under heating and reflux conditions. Thereafter, the internal temperature was lowered to 60 ° C., and 1.8 parts by weight of sodium hydroxide was added and stirred for 1 hour.
Ethyl acetate and water were added to the obtained reaction mixture, and after separating into an organic layer and an aqueous layer, the aqueous layer was removed and water was further added to wash the organic layer. The organic layer was concentrated under reduced pressure using a rotary evaporator, and the obtained black product was redissolved in 100 parts by weight of acetone, 0.5 parts by weight of a 30% aqueous solution of sodium hydroxide was added, and stirred for 2 hours under heating and reflux conditions. . Ethyl acetate and water were again added to the obtained reaction mixture, and the washing operation was repeated three times. The organic layer was concentrated under reduced pressure using a rotary evaporator, and the residual solvent was removed at high temperature (150 ° C.) to obtain the epoxy resin of the present invention (7.3 parts by weight, recovery rate: 101%).
The epoxy equivalent (EEW) of the obtained compound is 335 g / eq. Met. In addition, when ¹ H-NMR of the obtained compound was measured, it is considered to be derived from glycidyl group in 2.5 to 2.9 ppm, 3.1 to 3.5 ppm, and 4.0 to 4.3 ppm (heavy DMSO). , A broad signal was observed. Moreover, when < ¹³ > C-NMR was measured, the signal considered to be derived from a glycidyl group was observed at 43.8 ppm, 50.9 ppm, 74.4 ppm (heavy DMSO).

(Examples 2 to 7)
The same as Example 1, except that the additive solvent described in Table 1 (a solvent having a Hildebrand solubility parameter (SP value) in the range of 17.9 to 26.5 MPa ^1/2 ) was used instead of isopropanol. The operation was performed to obtain epoxy resins of Examples 2 to 7. The respective recovery and epoxy equivalent (EEW) are described in Table 1.

(Comparative Examples 1 to 4)
Example 1 was used except that the additive solvent described in Table 1 (solvent in which Hildebrand solubility parameter (SP value) is less than 17.9 MPa ^1/2 or greater than 26.5 MPa ^1/2 ) was used instead of isopropanol. The same operation was performed to obtain epoxy resins of Comparative Examples 1 to 4. The respective recovery and epoxy equivalent (EEW) are described in Table 1.

(Comparative example 5)
The same operation as in Example 1 was carried out except that the isopropanol added in Example 1 was not added, and an epoxy resin of Comparative Example 5 was obtained. The respective recovery and epoxy equivalent (EEW) are described in Table 1.

Evaluation test 1 (solubility of epoxy compound)
The solubility with respect to the solvent of the epoxy resin obtained in Examples 1-7 and Comparative Examples 1-5 was evaluated. 10 mL of chloroform was added to 100 mg of the sample, the one completely dissolved was ○, the one with some undissolved was 残 り, the one not completely dissolved was x, and the results are shown in Table 1.

(Table 1)

(Example 8)
The epoxy resin of Example 8 was obtained in the same manner as in Example 1 except that tetraethylammonium bromide was used instead of tetraethylammonium chloride. The respective recovery rates and epoxy equivalent weights (EEW) are described in Table 2.

(Example 9)
An epoxy resin of Example 9 was obtained in the same manner as in Example 1 except that 0.15 parts by weight of sodium iodide was added in addition to tetraethylammonium chloride as a catalyst. The respective recovery rates and epoxy equivalent weights (EEW) are described in Table 2.

(Example 10)
The epoxy resin of Example 10 was obtained in the same manner as in Example 1 except that the amount of isopropanol to be added was changed to 11 parts by weight (15% by weight to epichlorohydrin). The respective recovery rates and epoxy equivalent weights (EEW) are described in Table 2.

(Example 11)
The epoxy resin of Example 11 was obtained in the same manner as in Example 3, except that tetraethylammonium bromide was used instead of tetraethylammonium chloride. The respective recovery rates and epoxy equivalent weights (EEW) are described in Table 2.

(Example 12)
A lignin cake is prepared by high temperature treatment in the presence of a base according to the method described in Example 1 (1) and (2) of JP-A-2016-060749 except that a Eucalyptus chip is used, and a lignin cake is produced at 60.degree. After drying with a hot air drier, the soluble portion was extracted with 9 volumes of acetone.
Using the obtained acetone extract of Eucalyptus kraft lignin as a raw material, the same operation as in Example 1 was performed to obtain an epoxy resin of Example 12. The respective recovery rates and epoxy equivalent weights (EEW) are described in Table 2.

Evaluation test 2 (glass transition point (Tg) measurement of cured product)
The epoxy resin obtained in Examples 1 to 3 and 8 to 12 and Comparative Example 5 and a phenol novolac resin (H-1, manufactured by Meiwa Kasei Co., Ltd., hydroxyl equivalent 103 g / eq.) Are mixed in a ratio of 1: 1. The epoxy resin composition of the present invention was made by dissolving in methyl ethyl ketone and adding 1 wt% of triphenylphosphine. Thereafter, the solvent is dried at 110 ° C. for 10 minutes and further heated at 150 ° C. for 1 hour and 175 ° C. for 4 hours to form a cured product of the present invention, and a differential scanning calorimeter (DSC) of the cured product of the present invention The glass transition temperature (Tg) was measured. The measurement results are described in Table 2.

(Table 2)

From the results of Table 1, the epoxy resins of Examples 1 to 6 synthesized using a solvent having a Hildebrand solubility parameter (SP value) in the range of 17.9 to 26.5 MPa ^1/2 have a recovery rate, epoxy It can be confirmed that both of the equivalents are good and the solvent solubility is also excellent. In contrast, the epoxy resins of Comparative Examples 1 to 4 synthesized using solvents in which Hildebrand's solubility parameter (SP value) is less than 17.9 MPa ^1/2 or greater than 26.5 MPa ^1/2 have an epoxy equivalent It can confirm that it is greatly inferior. Moreover, in Comparative Example 5 synthesized without adding a solvent, it is also found that the epoxy equivalent is 400 or more, and good epoxidation does not progress. From this, it is suggested that the effect of adding a solvent having a Hildebrand solubility parameter (SP value) in the range of 17.9 to 26.5 MPa ^1/2 is high at the time of epoxidation of lignin.

Further, from the results of Table 2, the epoxy resins of Examples 8 and 11 in which tetraethylammonium bromide was used as the catalyst, and the epoxy resin of Example 9 in which both tetraethylammonium chloride and sodium iodide were added had both the recovery rate and the epoxy equivalent. It is improved and the utility of these catalyst systems can be confirmed. Furthermore, when the epoxy resin cured material of this invention was created and the glass transition point was measured, all showed the high value of 150 degreeC or more, and it became clear that it has the outstanding heat resistance.
From the above results, the method for producing an epoxy resin using lignin of the present invention as a raw material is very useful, and the epoxy resin obtained by the method and the cured product thereof have excellent properties. It can be said.

Claims (11)

In the method for producing an epoxy resin obtained by reacting lignin obtained by heat treatment of woody biomass in the presence of a base and an epihalohydrin, the solubility parameter (SP value) of Hildebrand during reaction is 17.9 to 26.5 MPa ^{1 A} method for producing an epoxy resin, which comprises adding a solvent in the range of ^1/2 .   The method for producing an epoxy resin according to claim 1, wherein the woody biomass is a broadleaf tree.   The method for producing an epoxy resin according to claim 1, wherein the lignin is soda anthraquinone lignin or kraft lignin.   The method for producing an epoxy resin according to any one of claims 1 to 3, wherein the lignin is a lignin purified by extraction with a solvent.   The method for producing an epoxy resin according to any one of claims 1 to 4, wherein the amount of the solvent added is in the range of 15 to 100% by weight based on epihalohydrin.   The method for producing an epoxy resin according to any one of claims 1 to 5, wherein the solvent is an alcohol or a ketone.   The method for producing an epoxy resin according to claim 6, wherein the solvent is an alcohol having 3 or less carbon atoms or a ketone having 4 or less carbon atoms.   Furthermore, the manufacturing method of the epoxy resin as described in any one of Claim 1 thru | or 7 which adds a quaternary ammonium salt as a catalyst.   The epoxy resin obtained by the manufacturing method as described in any one of Claims 1-8.   An epoxy resin composition comprising the epoxy resin according to claim 9 and a curing agent and / or a curing accelerator. A cured product obtained by curing the epoxy resin composition according to claim 10.