JP2013221113A - Lignin-derived epoxy resin composition and application thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lignin-derived epoxy resin capable of forming a cured product having a high glass transition point and a high thermal decomposition temperature without raising the cost of lignin raw material.SOLUTION: A lignin-derived epoxy resin composition contains unmodified lignin by steam blasting, a bi- or higher functional epoxy resin, and a catalyst for self-polymerization of the epoxy resin, wherein the compounding ratio of the lignin to the epoxy resin is 0.5 to <1.4 in terms of the ratio of the number of hydroxyl groups in the lignin to the number of epoxy groups in the epoxy resin. The present invention discloses a cured product of the composition, a prepreg, a varnish, electronic equipment and electrical equipment.

Description

  The present invention relates to a lignin-derived epoxy resin composition that gives a cured product having both a glass transition point and a high thermal decomposition temperature, and uses thereof.

  In recent years, with the improvement in performance of electronic and electrical components, the amount of heat generated by the components tends to increase. Therefore, a resin that is often used for electronic / electrical parts is desired to have a heat resistance that is as high as possible and that does not change its properties and has excellent heat resistance. In general, when a polymer material is heated, reversible physical changes such as softening, melting, and flow, and irreversible chemical changes of molecular chain breakage due to heat occur. In particular, a cured epoxy resin has a high glass transition temperature (hereinafter abbreviated as Tg) having a meaning of a physical chemical change, and has a high Tg (Glass-transition Temperature) and heat accompanied by an irreversible chemical change. It is required that the decomposition temperature (Decomposition Temperature) is high. In the present invention, as the thermal decomposition temperature, the temperature when 5% by weight of the resin cured product is decomposed by heat when it is heated (5% by weight thermal loss temperature: Td5) is taken as one of the heat resistance indicators. Use.

  It is known that Tg depends on the crosslink density and molecular structure of the cured epoxy resin, generally has a high crosslink density, and a cured product using a rigid structure such as biphenyl or naphthalene exhibits a high Tg. This is because Tg is caused by the micro-Brownian motion of the polymer segment, and therefore, the higher the crosslink density and the more rigid the molecular structure, the more difficult each segment causes the micro-Brownian motion.

  Td5 is determined mainly by the decomposition of the polymer main chain (radical depolymerization), and is a temperature at which a predetermined weight loss of the polymer occurs due to thermal decomposition. The likelihood of thermal decomposition is determined by the bond dissociation energy of the molecular structural unit. Therefore, in order to obtain a cured epoxy resin having a high thermal decomposition starting temperature, a polymer having a large bond dissociation energy of a chemical bond constituting the polymer main chain may be used. Specifically, an aromatic material and a polycyclic aromatic material are preferable to an aliphatic material.

  In particular, in the case of an insulating material for an electrical device, it is important for an insulating material using a resin that the heat decomposition temperature is higher than the glass transition point to ensure the heat resistant life of the insulating material.

On the other hand, chemical products have been made from fossil resources such as petroleum. In recent years, with the increase in the amount of CO ₂ generated by incineration of fossil resources, measures to prevent global warming have attracted attention. Therefore, from the viewpoint of preventing global warming, the demand for biomass-derived plastics is increasing by introducing the concept of carbon neutral.

  Until now, only plastics made from fossil resources have been used, but the application of biomass-derived plastics has become active in fields that require high reliability, such as OA-related members, household appliances members, and automobile members.

  Specific examples include thermoplastic resins such as PLA (polylactic acid), esterified starch, PTT (Poly-Trimethylene Telephthalate), and PHA (PolyHydroxy Alkanoate). These are, for example, resins made from food such as sugar cane and fermented monomers as raw materials, microbial production resins, and the like.

  On the other hand, lignin has attracted attention in the field of thermosetting resins. Currently available lignin, which is commercially available, is lignin sulfonic acid obtained as a by-product in the papermaking process. However, since this lignin sulfonic acid is almost insoluble in an organic solvent and has almost no softening temperature, it was difficult to apply it to a thermosetting resin. Thus, coexistence of high Tg and high Td5 of the lignin-derived epoxy resin composition was difficult.

  An alkaline cooking method is known as a method for producing lignin from plant resources, but the obtained lignin is hardly dissolved in an organic solvent and is difficult to be practically used with the current technology.

JP2011-184645A JP 2010-254820 A JP 2012-07143 A

  In order to use epoxy resin for electronic and electrical equipment, reliability of thermal, electrical and mechanical strength is required. Therefore, the present inventors obtained a low molecular weight lignin having a softening temperature and soluble in an organic solvent by a steam explosion method as compared with natural lignin, and using this, the lignin derived from lignin excellent in Td5 and Tg. The epoxy resin hardened material was examined earnestly. As a result, it was found that the cured product of the lignin-derived epoxy resin composition obtained by reacting the low molecular weight lignin obtained by the steam explosion method with the epoxy resin has a significantly different Td5 depending on the blending ratio of the lignin and the epoxy resin. The reason was intensively studied, and the cause of the low Td5 of the cured product was the low Td5 of the lignin itself. As a result, the cured product of the epoxy resin composition using lignin also had to have a low Td5.

  As publicly known examples of thermosetting resins using lignin, there are Patent Documents 1 to 3. Patent Document 1 discloses an insulating polymer material composition comprising a plant-derived polyphenol derivative obtained by decomposing biomass, such as lignin, epoxidized vegetable oil such as epoxidized linseed oil, coal ash, and a silane coupling agent. Yes. This composition uses a plant-derived epoxy resin and a plant-derived polyphenol derivative in place of petroleum-derived raw materials, and adds coal ash, which is essentially waste, to reduce the environmental burden. In addition, imidazole, a tertiary amine, etc. are used as a hardening accelerator. The Tg of the cured product is 55 ° C. when no silane coupling agent is added, and 78 ° C. is the highest even when 0.4% of the silane coupling agent is added. Further, Td is not described.

  In patent document 2, 1-75 weight% of plant origin polyphenols (lignin) and the plant origin resin of the semi-hardened state of an epoxy resin are disclosed. As a curing accelerator, 0.01 to 5% by weight of an imidazole, a tertiary amine or an aromatic amine is added. This document describes the Tg of the cured product (in the examples, 130 ° C. or lower), but does not describe Td. Moreover, it is a phenolic hydroxyl group that reacts with the epoxy group, and the reaction between the alcoholic hydroxyl group and the epoxy group is not considered.

  In Patent Document 3, an epoxy resin composition using fully acylated lignin is disclosed, and the feature of this composition is that lignin is acylated to impart solvent solubility, but is expected to be inexpensive. It is not preferable that the cost of the lignin-derived material is increased by chemical treatment. Patent Document 3 describes that the glass transition point of the cured product is 60 to 130 ° C, and the thermal decomposition temperature of 1% weight reduction is about 280 ° C.

  Conventionally, although the glass transition point Tg of the lignin-derived epoxy resin composition is high, there is a problem that the thermal decomposition temperature Td5 is relatively low. The reason is that the crosslinking reaction between lignin and the epoxy resin is insufficient, and it is difficult to maintain a high thermal decomposition temperature Td5 by the epoxy resin.

  An object of the present invention is to provide a lignin-derived epoxy resin composition that gives a cured product having a high glass transition point Tg and a high thermal decomposition temperature Td5 without increasing the cost of the lignin raw material.

  The present invention is a composition comprising an unmodified lignin by steam explosion, a bifunctional or higher functional epoxy resin, and a self-polymerizable catalyst of the epoxy resin, wherein the blending ratio of the lignin and the epoxy resin is a hydroxyl group of the lignin. The number / epoxy group number of the epoxy resin is from 0.5 to less than 1.4.

  The present invention is to extract a lignin raw material obtained by steam explosion with a solvent to select a lignin having a desired molecular weight, and mix this with a bifunctional or higher epoxy resin and an epoxy resin self-polymerizable catalyst. And an epoxy resin are blended at an arbitrary blending ratio, and this is heated / cured or photocured to obtain a cured product having a high glass transition point Tg and a thermal decomposition temperature Td5.

The reason why the lignin-derived epoxy resin composition of the present invention exhibits a high glass transition point Tg and a thermal decomposition temperature Td5 is that a part of the epoxy resin that is more mobile than the lignin molecule is heated at the initial stage of heating or light irradiation of the composition. Self-polymerization is initiated in the presence of the self-polymerizable catalyst, and then the polymerization reaction (cross-linking reaction) of the lignin hydroxyl group and the epoxy group of the epoxy resin proceeds and is completely cured. It is thought that the hardened | cured material in which the crosslinked part which the lignin and the epoxy resin reacted coexist is formed. As a result, it is considered that the self-polymerized epoxy resin portion contributes to a high thermal decomposition temperature Td5, and the crosslinked structure of lignin and epoxy resin contributes to a high glass transition point Tg.

  According to the present invention, it is possible to obtain a lignin-derived epoxy resin composition that is effective in reducing the environmental load, such as reducing the amount of fossil resources used, and gives a cured product having a high Tg and Td5. Therefore, various heat-resistant products using the same can be provided.

The schematic diagram which shows the typical presumed structure of the low molecular weight lignin obtained from natural lignin by steam explosion. The thermogravimetry decreasing rate curve of the hardened | cured material of the lignin origin epoxy resin by this invention. Sectional drawing which shows the structure of the printed board to which this invention is applied. The perspective view which shows the structure of the motor to which this invention is applied.

Before describing the present invention in detail, definitions of main technical terms used in the present specification will be given below.
[1] Steam-explosive lignin: Water pressure is injected into woody biomass, then the pressure is released instantly and the woody biomass is steam-exploded, and after removing cellulose and hemicellulose components, acetone, alcohol, etc. Extracted with an organic solvent. The steam-explosive lignin used in the present invention is not chemically modified, and the terminal is considered to have many hydroxyl groups from the measurement of hydroxyl equivalent. The reason for this is that lignin by steam explosion has a molecular weight of 20000 or less after removal of the cellulose component and hemicellulose component due to high-pressure hydrolysis, and has a hydroxyl group at the end and dissolves in an ordinary solvent. Therefore, a process that increases the cost of lignin, for example, a chemical modification process is not required, and the cost increase factor of the raw material can be avoided.

  In the following description, the term “lignin” may be used in the present specification, which means non-chemically modified lignin obtained by steam explosion.

  [2] Td5: Temperature at a weight loss rate of 5% as measured by thermogravimetry at a heating rate of 10 ° C./min in nitrogen. It is calculated | required from the thermogravimetry decreasing rate curve shown in FIG. Seiko Instruments Co., Ltd., TG / DTA6200 type was used to measure the thermal weight loss rate of the cured epoxy resin. The measurement was performed under a nitrogen atmosphere (200 ml / min). The measurement temperature is room temperature to 700 ° C. In this specification, the thermal decomposition start temperature was evaluated by Td5.

  [3] Tg: Using IT Measurement Control Co., Ltd., DVA-200, the glass transition point (Tg) of the cured epoxy resin film was determined by a tensile mode at a heating rate of 5 ° C./min. The storage elastic modulus (Er) and the loss elastic modulus (Ei) were measured to determine the ratio (Er / Ei = tan δ), and the peak temperature of tan δ was defined as Tg. The measurement temperature is room temperature to 300 ° C. in an air atmosphere.

  [4] Self-polymerization: The epoxy resins are polymerized by the action of the polymerization catalyst. In this case, the catalyst also functions as a curing agent for the epoxy resin. Even in the presence of polymerization components such as polyphenols such as lignin, epoxy resin molecules that move more easily than lignin molecules in the presence of a specific polymerization catalyst at low temperatures, the polymerization reaction between the epoxy resins proceeds first. Reaction of lignin and epoxy resin proceeds. In this case, the polymerization catalyst also functions as an accelerator for the crosslinking reaction of the epoxy resin by lignin.

  [5] Self-polymerization catalyst: a catalyst for the crosslinking reaction between epoxy resin and lignin and at the same time a catalyst for self-polymerization of epoxy resin, specifically, Lewis bases such as imidazole and tertiary amine, There are Lewis acids.

  In the initial stage of the curing reaction of the lignin-derived epoxy resin composition of the present invention, the catalyst is in a state where the reaction of the epoxy resin is more likely to occur than the reaction of lignin and the epoxy resin. This is a reaction between an epoxy resin and a polymerization catalyst, but is defined as a self-polymerization reaction of the epoxy resin. In the initial stage of the curing reaction of the lignin-derived epoxy resin composition, the catalyst does not exhibit a catalytic action for the crosslinking reaction between the lignin component and the epoxy resin. In the initial stage of the curing reaction of the lignin-derived epoxy resin composition, for example, at a low temperature, the epoxy resin molecules move more easily than the lignin molecules, and can react with the catalyst. Following the self-polymerization reaction of the epoxy resin, the lignin, whose temperature has risen and the molecules have moved easily, undergoes a crosslinking reaction with the epoxy resin. In addition, when there are too many self-polymerization reactions of an epoxy resin, Tg of hardened | cured material will become low. The catalyst amount is adjusted to 0.01 to 5% by weight, particularly preferably 0.1 to 2.5% by weight, based on the weight of the lignin-derived epoxy resin composition.

  On the other hand, following the self-polymerization reaction of the epoxy resin, a crosslinking reaction between lignin and the epoxy resin occurs. Here, the catalyst functions as a catalyst for a crosslinking reaction between lignin and an epoxy resin, and as a result, the cured product has a high glass transition point and a high Td5. The glass transition point Tg of the hardened | cured material by this invention is 160 degreeC or more, and Td5 is 330 degreeC or more.

  Embodiments of the present invention will be described below.

  (1) A lignin-derived epoxy resin composition is cured by heat or light.

  (2) The lignin contains a phenolic hydroxyl group and an alcoholic hydroxyl group. Thereby, lignin reacts easily with an epoxy resin.

  (3) It is preferable that the lignin is extracted with an organic solvent after water pressure is injected into the woody biomass, and then the pressure is instantaneously released to steam-crack the woody biomass to remove the cellulose component and hemicellulose component.

  (4) The lignin preferably has a weight average molecular weight of 300 to 20000 and a terminal hydroxyl group. This lignin dissolves well in common organic solvents.

  (5) It is preferable that the hydroxyl equivalent of the said lignin is 80-600 g / eq.

  (6) A varnish containing the above lignin-derived epoxy resin composition and an organic solvent for dissolving the composition, wherein the concentration of the lignin-derived epoxy resin composition is 10 to 90% by weight of the varnish.

  (7) The solvent includes one selected from alcohols, ketones, ethers, aromatics, and aliphatics.

  (8) A prepreg can be produced by impregnating and drying the varnish into a fibrous base material such as a glass woven fabric or a non-woven fabric. Moreover, a printed circuit board, an electronic device, etc. can be created using this prepreg.

  (9) Various fillers can be blended with the lignin-derived epoxy resin composition to produce a molding material, and electronic devices, motor stators and rotors can be produced using the molding material.

  The lignin-derived epoxy resin composition of the present invention comprises an epoxy resin, lignin as a crosslinking agent for the epoxy resin, and a polymerization catalyst as basic components. The blending component is blended so that B / A is 0.5 ≦ B / A <1.4 when expressed by the number of hydroxyl groups (B) of lignin / the number of epoxy groups (A). At this blending ratio, the cured product of the lignin-derived epoxy resin composition has a high Td5 and a relatively high glass transition point Tg.

  When 0.5> B / A, since the epoxy resin component is large, the proportion of self-polymerization of the epoxy resin is large, and the adhesiveness with the base material, which is a characteristic of the cured epoxy resin, is lowered. Further, the glass transition point Tg tends to be relatively low.

  When B / A ≧ 1.0, the Tg of the cured product of the lignin-derived epoxy resin composition is high but Td5 tends to decrease, but it can be put to practical use depending on the application. However, when B / A> 1.4, Td5 of the cured product tends to be greatly reduced. The catalyst amount is preferably 0.01 to 5% by weight, particularly preferably 0.1 to 2.5% by weight, based on the weight of the lignin-derived epoxy resin composition.

  The glass transition point of the cured product of the lignin-derived epoxy resin composition of the present invention is 160 ° C. or higher, and the thermal decomposition temperature Td5 is 330 ° C. or higher.

  The steam-explosive lignin is preferably one obtained by steam-exploding woody biomass, which is extracted with an organic solvent after removing the cellulose component and hemicellulose component, and is a group polymerizable with a curing agent such as a phenolic hydroxyl group and an alcoholic hydroxyl group. And is soluble in one or more organic solvents in a weight average molecular weight range of 300-20000.

  The weight average molecular weight of lignin is preferably 300 to 20000, more preferably 400 to 16000, and particularly preferably 500 to 10,000 in terms of polystyrene. When the weight average molecular weight of lignin exceeds 20000, the solubility in an organic solvent is rapidly lowered. If the weight average molecular weight is less than 300, Tg and Td5 of the cured resin utilizing the structure of lignin is lowered.

  In order to obtain a cured product obtained by curing the lignin-derived epoxy resin composition, the epoxy resin is a bifunctional epoxy resin, Tg is 170 ° C. or higher, preferably 190 ° C. or higher, and Td5 is A cured product of the lignin-derived epoxy resin composition characterized by being 340 ° C. or higher, preferably 350 ° C. or higher is preferable.

The epoxy resin of the cured product obtained by curing the lignin-derived epoxy resin composition is a trifunctional or higher functional epoxy resin, and has a glass transition point of 200 ° C. or higher,
Td5 is preferably 340 ° C. or higher.

  The weight average molecular weight of lignin was measured by gel permeation chromatography (GPC: Gel Permeation Chromatography) and expressed as a polystyrene conversion value.

  The basic skeleton of lignin is generally a crosslinked polymer having a hydroxyphenylpropane unit as a basic unit. There is no restriction | limiting in the raw material of lignin, A cedar, a pine, a cypress, a beech, a bamboo, bagasse etc. can be used.

  In the steam explosion method, generally, woody biomass is put in a pressure vessel, steam having a pressure of 2 to 5.5 MPa is used, and the cooking time is preferably 1 to 25 minutes. Water is preferable as the water vapor source used for the explosion. In addition, compounds having a hydroxyl group such as phenols, alcohols, glycols and the like can also be used by mixing with water. However, when other than water is used, it is considered that the terminal hydroxyl group of the obtained lignin is likely to be masked. This is not preferable because reactivity with the epoxy resin is impaired. Therefore, it is preferable to select a method for producing lignin in which the terminal hydroxyl group of lignin is not masked.

  In order to obtain low molecular weight lignin from the crushed water vapor, the low molecular weight lignin is extracted by removing the cellulose component and hemicellulose component by washing with water and then dissolving in an organic solvent. Removal of the solvent gives a dry low molecular weight lignin.

  Organic solvents used for extraction of lignin are toluene, hexane, cyclohexanone, diethyl ether, ethyl methyl ether, methyl-iso-butyl ketone, tetrahydrofuran, tetrahydropyran, 2-methoxyethanol, 2-butanone, methanol, ethanol, n-propanol, iso-propanol, n-butanol, ter-butanol, ethyl acetate and the like. Of these, a water-soluble solvent may be a mixed solvent with water.

  The epoxy resin used in the present invention includes bisphenol A type epoxy, bisphenol S type epoxy, bisphenol F type epoxy, bisphenol AD type epoxy, phenol novolac type epoxy, biphenyl type epoxy, cresol novolac type epoxy, dicyclopentadiene type epoxy, naphthalene. There are mold epoxies. Epoxidized castor oil and epoxidized soybean oil can also be used.

  Bifunctional epoxy resin molecules and trifunctional or higher functional epoxy resin molecules behave differently in compositions containing lignin-epoxy resin-self-polymerizable catalysts. Trifunctional and higher functional epoxy resin molecules are less reactive in the composition than bifunctional epoxy resin molecules due to steric hindrance, etc., so the proportion of trifunctional and higher functional epoxy resins is slightly lower, and Td5 is a bifunctional epoxy resin. There is a tendency to be slightly lower than when using.

  In addition, epoxidized lignin obtained by epoxidizing hydroxyl groups of various lignins with epichlorohydrin can be used (Japanese Patent Laid-Open No. 2008-326634).

  Examples of the self-polymerizable catalyst for the epoxy resin of the present invention include an anionic polymerization catalyst and a cationic polymerization catalyst. The former includes Lewis bases such as tertiary amines and imidazoles, and the latter includes Lewis acids and photoinitiating catalysts.

  Specific examples of the tertiary amine include tris (dimethylaminomethyl) phenol, benzylmethylamine, and 1,8-azabicyclo [5.4.0] -undecene-7.

  Examples of imidazoles include 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 1-benzyl-2-methylimidazole, 2 -Phenylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 2,4-diamino-6- [2'-methylimidazolyl] -(1 ')]-ethyl-s-triazine, 2,4-diamino-6- [2'-undecylimidazolyl- (1')]-ethyl-s-triazine, 2,4-diamino-6- [ 2'-ethyl-4'-methylimidazolyl- (1 ')]-ethyl-s-triazine, , 4-Diamino-6- [2'-methylimidazolyl- (1 ')]-ethyl-s-triazine isocyanuric acid adduct, 2-phenylimidazole isocyanuric acid adduct, 2-phenyl-4-methyl-5-hydroxy Methylimidazole, 2,3-dihydro-1H-pyrrolo [1,2-a] benzimidazole, 1-dodecyl-2-methyl-3-benzylimidazolium chloride, 2-phenylimidazoline, 2-methylimidazoline, 2-4 -Diamino-6-vinyl-s-triazine, 2,4-diamino-6-methacryloyloxyethyl-s-triazine.

  There are also epoxy-imidazole adducts, epoxy-phenol-borate ester blends, and the like.

  Examples of Lewis acids include boron trifluoride monoethyl complex salt and boron trifluoride monomethylamine.

  Photoinitiators include triphenylsulfonium hexafluoroantimonate, triphenylsulfonium phosphate, p- (phenylthio) phenyldiphenylsulfonium hexafluoroantimonate, p- (phenylthio) phenyldiphenylsulfonium hexafluorophosphate, 4-chlorophenyldiphenylsulfonium hexafluoro. Phosphate, 4-chlorophenyldiphenylsulfonium hexafluoroantimonate, bis [4- (diphenylsulfonio) phenyl] sulfide bishexafluorophosphate, bis [4- (diphenylsulfonio) phenyl] sulfide bishexafluoroantimonate, (2,4-Cyclopentadien-1-yl) [(1-methylethyl) benzene] -Fe-he Fluoro-phosphate, there is a diallyl iodonium hexafluoroantimonate and the like.

  The lignin-derived epoxy resin composition of the present invention can also be used for molding materials. Therefore, various organic / inorganic fillers, flame retardants, coupling agents, ion trappers, heat stabilizers and the like can be blended according to the purpose. As the inorganic filler, it is preferable to use a low thermal expansion filler such as fused silica in order to reduce the thermal expansion coefficient. In order to achieve high thermal conductivity, boron nitride, aluminum nitride or alumina is preferred. The filler particle shape is preferably spherical or substantially spherical from the viewpoint of flowability into fine gaps and controllability of permeability. The average particle size is preferably 0.1 to 25 μm. If it is less than 0.1 μm, thixotropic property is imparted to the resin composition and the fluidity is inferior.

  On the other hand, if the average particle diameter exceeds 25 μm, the filler tends to settle. The blending ratio of the inorganic filler can be adjusted in the range of 0 to 95% by weight with respect to the epoxy resin composition. The range of 30 to 85% by weight is particularly preferable, and 35 to 80% by weight is more preferable. If it is less than 30% by weight, the effect of reducing the coefficient of thermal expansion due to the addition of filler tends to be small, but even in the case of 0% by weight, there may be cases where sufficient practical reliability can be secured depending on the shape and size of the semiconductor element. is there. On the other hand, when the blending amount of the filler exceeds 95% by weight, the epoxy resin composition has a high viscosity, and the fluidity at the time of encapsulation tends to decrease.

  The lignin-derived epoxy resin composition of the present invention can be dissolved in a solvent. Therefore, the lignin-derived epoxy resin composition of the present invention may be dissolved in a solvent and used as a varnish. The lignin-derived epoxy resin composition varnish of the present invention is impregnated and dried in a glass cloth to prepare a prepreg, which is laminated, pressed and heated together with a plurality of copper foils to produce a copper-clad laminate. be able to. Solvents for producing varnish include toluene, xylene, benzene, methanol, methyl ethyl ketone, phenol, methyl isobutyl ketone, N-methylpyrrolidone, dimethylformamide, cyclohexanone, methyl cellosolve (ethylene glycol monomethyl ether), ethyl acetate, methyl acetate, There are tetrahydrofuran, isopropanol, n-butanol, tert-butanol and the like.

  The varnish contains 20 to 80% by weight of a solvent and 80 to 20% by weight of a lignin-derived epoxy resin composition (including a self-polymerizable catalyst for epoxy resin) as essential components, and other mixtures such as curing agents and coupling agents. Become.

  A flame retardant may be mixed in the lignin-derived epoxy resin composition of the present invention according to the purpose. Examples of flame retardants include red phosphorus, phosphate esters, melamine, melamine derivatives, compounds having a triazine ring, cyanuric acid derivatives, zinc oxide, iron oxide, molybdenum oxide, magnesium hydroxide, and aluminum hydroxide. Or it can mix | blend in combination of 2 or more types.

Other uses of the epoxy resin composition of the present invention include the aforementioned prepreg, various coils such as printed wiring boards and rotating electric machines, static induction electric appliances, paints, and electronic devices used as insulating materials and sealing materials. is there. According to the present invention, it is possible to produce a cured product having a high glass transition point Tg and a high thermal decomposition temperature Td5 in which the resin composition is used for insulating materials for various electric devices, semiconductor molding materials, insulating coatings, and the like. It is.

(1) Test materials The resins used in the present invention and others are shown below. Hereinafter, materials are indicated by trade names or abbreviations.

1-1: Low molecular weight lignin The cedar material was put into a raw material in a pressure vessel (capacity: 2 L) of a steam explosion apparatus, and steam explosion was performed after a pressure of 2.5 MPa and a steaming time of 10 minutes. The explosion was washed with 100 times the amount of the explosion for 12 hours. The low-molecular-weight lignin was extracted using 10 times the amount of methanol after drying the crushed material under reduced pressure. Methanol was removed from the extract by vacuum distillation to obtain a dried low molecular weight cedar lignin. The obtained lignin has a weight average molecular weight of 1200 and a hydroxyl group equivalent of 105 g / eq.

  Similarly, low molecular weight lignin obtained by performing steam explosion using bamboo as a raw material under conditions of a pressure of 3.6 MPa and a steaming time of 5 minutes, washing the explosion with water and then extracting with acetone, has a weight average molecular weight of 2600 and a hydroxyl group equivalent is 130 g / eq.

  All of these were dissolved in methanol, ethanol, n-propanol, 2-butanone, 2-methoxypropanol, tetrahydrofuran, cyclohexanone, diethyl ether, ethyl methyl ether, and methyl-iso-butyl ketone.

1-2; Epoxy Resin The epoxy resin is a commercially available bifunctional epoxy resin, bisphenol type jER828 (manufactured by Mitsubishi Chemical, epoxy equivalent 195 e / eq, liquid), and a tri- or higher functional cresol novolac type epoxy resin ESCN190. (Manufactured by Sumitomo Chemical Co., Ltd., ESCN190, epoxy equivalent 195 e / eq, mp = 65 ° C.). As an epoxy resin curing agent, lignin made from cedar and bamboo was used.

1-3: Polymerization catalyst Adduct type imidazole P200 (trade name; manufactured by Mitsubishi Chemical Corporation) was used as a polymerization catalyst. In the case of the molding material, 2-phenyl-4-methyl-5-hydroxymethylimidazole [(trade name: 2P4MHZ (manufactured by Shikoku Kasei Kogyo))] which is an imidazole catalyst was used.

  Boron trifluoride monoethylamine complex (hereinafter abbreviated as FBEA, manufactured by Hashimoto Kasei) is used for Lewis acids, and diazabicycloundecene (1,8-diazabiccyclo [5.4.0] undec- is used for tertiary amines. 7-ene), hereinafter abbreviated as DBU, manufactured by Wako Pure Chemical Industries, Ltd.).

  As a photoinitiator, Cyend SI-180L (hereinafter abbreviated as 180L, manufactured by Sanshin Chemical Co., Ltd.), which is a PF6-sulfonium salt of a cationic polymerization initiator, was used. FBEA, DBU, and 180L were used as a mixed solvent for varnish.

1-4; Varnish solvent A mixed solvent of 2-butanone (manufactured by Wako Pure Chemical Industries, special grade) and 2-methoxyethanol (manufactured by Wako Pure Chemical Industries, special grade) was used as the varnish solvent.

1-5; three-component filler As silica filler, BF100 (manufactured by Nippon Aerosil Co., Ltd.) having an average particle diameter of 22 μm, FB30X (manufactured by Electrochemical) having an average particle diameter of 8.7 μm, and SO25R (manufactured by Tatsumori Co., Ltd.) having an average particle diameter of 0.7 μm ) Was used.

1-6; Coupling agent 3-glycidoxypropyltrimethoxysilane KBM-403 (manufactured by Shin-Etsu Chemical Co., Ltd.) was used as a coupling agent.

1-7; Release agent Montanic acid ester (manufactured by Clariant Japan, Licowax E) was used as the release agent.

(1) Preparation of varnish and curing method Arbitrary amount of hydroxyl group equivalent of lignin and epoxy group equivalent of epoxy resin used for the curing agent was calculated, and 2.0% by weight of polymerization catalyst P200 was added to the resin, and 2-butanone / 2 -An equivalent weight mixed solvent of methoxyethanol was added to the resin and the same weight, and a big rotor (manufactured by ASONE;
BR-2 type) was stirred overnight to prepare a varnish.

  The varnish was applied onto a polyimide film Iupilex 50-S (registered trademark; manufactured by Ube Industries) with a bar coater adjusted so that the resin thickness after curing was 50 to 100 μm. This was put into a hot air dryer, and conditions of 50 ° C./1 hour + 75 ° C./1 hour + 100 ° C./1 hour + 150/1 hour + 180/2 hours (the varnish using ESCN190 was further added at 200 ° C./2 hours) Was heated stepwise to obtain a cured epoxy resin film free of bubbles.

(2) Production of molding material and curing method The composition of the molding material is an arbitrary amount of the hydroxyl equivalent of lignin used in the curing agent and the epoxy equivalent of the epoxy resin. The polymerization catalyst 2P4MHZ is 2.0% by weight of the resin, silane The coupling agent (KBM403, manufactured by Shin-Etsu Chemical Co., Ltd.) was mixed with 4.0% by weight of resin, and the release agent (Licowax E) was mixed with 2.5% by weight of resin. The filler was blended with a three-component filler with a blending amount of about 75% by weight of the molding material.

  These were mixed in a plastic bag and then kneaded using a mixing roll (manufactured by Kansai Roll Co., Ltd., roll size: 200 mmφ × length 500 mm) to produce a molding material. The roll temperature was 100 ° C for the low temperature roll and 110 ° C for the high temperature roll. The kneading time of the roll was 10 minutes after the molding material was wound around the roll. The kneaded product was pulverized into a molding material.

  An arbitrary amount of the molding material was taken, put into a transfer molding machine TPE50-30 (manufactured by Towa Seiki Co., Ltd.), pressurized and heated, and molded into various shapes. The molding temperature is 190 ° C. and the molding pressure is 3.8 MPa. The molding time was 3.0 minutes, and after the molding, the resin was further cured after 200 ° C / 6 hours.

(3) Measurement method 4-1: Hydroxyl equivalent The hydroxyl equivalent represents the weight (g) of the resin containing 1 g equivalent of the hydroxyl group. The unit is g / eq. The hydroxyl equivalent of lignin is the sum of phenolic hydroxyl groups and alcoholic hydroxyl groups. The measurement was performed by an acetic anhydride-pyridine method in accordance with JIS K 0070.

4-2; TG / DTA (differential thermal-thermogravimetric simultaneous measurement)
Using TG / DTA6200 manufactured by Seiko Instruments, the relationship between the thermal weight reduction rate of the cured epoxy resin and the temperature was measured. The measurement was performed under a nitrogen atmosphere (200 ml / min) at a heating rate of 10 ° C./min.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, the scope of the present invention is not limited to these Examples. The blending amount of lignin described in Table 1 is the number of hydroxyl groups, in Example 1, the blending amount is 33 g per 100 g of epoxy resin, and the blending ratio of lignin is the number of hydroxyl groups of lignin (B) / the number of epoxy groups of epoxy resin (A). Indicates.

Example 1
As shown in Table 1, 33 g of bamboo lignin and 100 g of jER828, 2.7 g of P200 as a curing catalyst, which is 2.0% by weight of the resin component, and an equal weight mixed solvent of 2-butano and 2-methoxyethanol Was added to a wide-mouth plastic bottle and stirred to prepare a varnish. And the film of the lignin origin epoxy resin hardened | cured material was obtained according to the conventional method. Td5 showed 402 degreeC and Tg showed 165 degreeC.

(Example 2)
With the composition shown in Table 1, a varnish was prepared according to Example 1, and a film that was a cured product of the lignin-derived epoxy resin composition was obtained. Td5 showed 396 degreeC and Tg showed 172 degreeC.

(Example 3)
With the composition shown in Table 1, a varnish was prepared according to Example 1, and a cured film of the lignin-derived epoxy resin composition was obtained. Td5 was 399 ° C. and Tg was 175 ° C.

Example 4
With the composition shown in Table 1, a varnish was prepared according to Example 1, and a cured film of the lignin-derived epoxy resin composition was obtained. Td5 was 346 ° C. and Tg was 173 ° C.

(Examples 5 to 8)
With the composition shown in Table 1, a varnish was prepared according to Example 1, and a cured film of the lignin-derived epoxy resin composition was obtained. Td5 showed 360-340 degreeC, and Tg showed 218-205 degreeC.

(Example 9 to Example 11)
By changing the kind of the polymerization catalyst, a varnish was prepared according to the blending composition shown in Table 1 according to Examples 1 to 8, and a cured film of a lignin-derived epoxy resin composition was obtained. Td5 was 398-401 degreeC, and Tg was 172-166 degreeC.

(Example 12)
Example 11 relates to the molding material, and as shown in Table 1, a molding material was prepared by adding 2% by weight of the resin content of cedar lignin, epoxy resin ESCN, filler and polymerization catalyst 2P4MHZ. Test pieces were prepared by transfer molding, and Td5 and Tg were determined. As a result, as shown in Table 1, Td5 of Example 11 was 386 ° C., and Tg was 212 ° C.

(Example 13)
Based on Example 11, Td5 and Tg which produced the molding material with the composition shown in Table 1 were calculated | required. As shown in Table 1, the results were Td5 of 375 ° C. and Tg of 216 ° C.

  The following reference examples do not show known techniques, and the resin component and the curing catalyst satisfy the conditions of the present invention, but the number of hydroxyl groups of lignin (B) / number of epoxy groups of epoxy resin (A) is the present invention. It is described in order to show the effectiveness of the definition of the number of hydroxyl groups (B) of the lignin of the present invention / the number of epoxy groups (A) of the epoxy resin.

(Reference Example 1)
As a composition outside the blending ratio of the present invention, an epoxy resin composition varnish was prepared from an epoxy resin, a polymerization catalyst P200, and a mixed solvent that did not contain a curing agent, and a cured product was obtained. The Td5 showed 386 degreeC and Tg showed 116 degreeC.

(Reference Example 2)
As a composition outside the blending ratio of the present invention, a lignin-derived epoxy resin composition varnish having a lignin hydroxyl group number (B) / epoxy resin epoxy group number (A) of 1.60 was prepared to obtain a cured product. The Td5 was 320 ° C. and the Tg was 180 ° C.

(Reference Example 3)
As a composition outside the blending ratio of the present invention, a molding material was produced with the composition shown in Table 1. Td5 was 290 ° C. and Tg was 190 ° C.

As a result, in the composition containing unmodified lignin by steam explosion, a bifunctional or higher functional epoxy resin, and a polymerizable catalyst for the epoxy resin, the blending ratio of the lignin and the epoxy resin is the number of hydroxyl groups of the lignin / epoxy. In the number of epoxy groups of the resin, the lignin-derived epoxy resin composition in which the mixing ratio of the number of hydroxyl groups of the lignin is 0.5 to 1.4,
It is clear that Td5 and Tg are higher than those of the comparative examples. Therefore, the lignin-derived epoxy resin composition of the present invention can be used for printed wiring boards, motors and the like.

(Example 13)
A glass cloth was impregnated with the lignin-derived epoxy resin composition varnish of Example 1 and dried to obtain a prepreg. Ten prepregs were laminated, copper foils were laminated on both sides, and this was pressurized and heat cured to obtain a laminate. A pattern is formed on the copper foil of the laminate 2 by a photolithography method, and a prepreg produced by impregnating a glass fiber cloth with the lignin-derived epoxy resin composition according to the present invention as shown in FIG. Printed wirings 4 and 5 were formed, and conductor plating 6 penetrating both sides was formed in the through hole 3 to form a printed wiring board. Both the Tg and Td5 of the laminate were high, and a good wiring board could be obtained.

(Example 14)
Using the molding material described in Example 12, a rotating machine shown in FIG. 4 was produced. In the figure, 16 is a rotor shaft of a rotating machine, 14 is a rotor bearing, 12 is a rotor magnet, 8 is a stator coil, and 10 is a stator frame. Molding was performed using a molding material, followed by heat curing. Both Tg and Td5 of the stator frame were high, and a good rotating machine could be obtained.

  The present invention relates to a lignin-derived epoxy resin composition capable of forming a cured product having a high glass transition point and a high thermal decomposition temperature without increasing the cost of a lignin raw material, and is excellent in electrical insulation and heat resistance. Therefore, it can be used as an insulating material for various electronic devices and electrical devices, and can be widely used for prepregs, paints, molded products, and the like.

Claims (19)

  A composition containing unmodified lignin by steam explosion, a bifunctional or higher functional epoxy resin, and a self-polymerizable catalyst of the epoxy resin, wherein the blending ratio of the lignin and the epoxy resin is the number of hydroxyl groups of the lignin (B) / Lepnin-derived epoxy resin composition, wherein the epoxy group number (A) of the epoxy resin is from 0.5 to less than 1.4.   2. The lignin-derived composition according to claim 1, wherein the blending ratio of the lignin and the epoxy resin is such that the number of hydroxyl groups of the lignin (B) / number of epoxy groups of the epoxy resin (A) is 0.5 to 1.2. Epoxy resin composition.   2. The lignin-derived epoxy resin composition according to claim 1, wherein the blending ratio of the lignin and the epoxy resin is such that the number of hydroxyl groups of the lignin / number of epoxy groups of the epoxy resin is 0.6 to less than 1. 3.   The said lignin contains a phenolic hydroxyl group, an alcoholic hydroxyl group, etc., The lignin origin epoxy resin composition in any one of Claims 1-3 characterized by the above-mentioned.   The lignin-derived epoxy resin composition according to any one of claims 1 to 3, wherein the lignin has a weight average molecular weight of 300 to 20,000.   The lignin-derived epoxy resin composition according to any one of claims 1 to 3, wherein the lignin is soluble in one or more organic solvents.   The lignin-derived epoxy resin composition according to claim 1, wherein the lignin has a hydroxyl group equivalent of 80 to 600 g / eq.   A cured product obtained by curing the lignin lignin-derived epoxy resin composition according to any one of claims 1 to 7, wherein the glass transition point is 160 ° C or higher, and the 5% by weight thermal weight reduction temperature is 330 ° C. Hardened | cured material of the epoxy resin composition derived from a lignin characterized by being more than degreeC.   A cured product obtained by curing the lignin lignin-derived epoxy resin composition according to claim 2, wherein the epoxy resin is a bifunctional epoxy resin, has a glass transition point of 170 ° C. or higher, and 5 wt% heat. Hardened | cured material of the lignin origin epoxy resin composition characterized by the weight reduction temperature being 340 degreeC or more.   A cured product obtained by curing the lignin lignin-derived epoxy resin composition according to claim 3, wherein the epoxy resin is bifunctional, has a glass transition point of 190 ° C or higher, and is reduced by 5% by weight. A cured product of a lignin-derived epoxy resin composition having a temperature of 350 ° C or higher.   A cured product obtained by curing the lignin lignin-derived epoxy resin composition according to claim 1, wherein the epoxy resin is a trifunctional or higher functional epoxy resin, and has a glass transition point of 200 ° C. or higher and 5 wt. A cured product of a lignin-derived epoxy resin composition having a% thermogravimetric decrease temperature of 340 ° C. or higher.   The lignin-derived epoxy resin composition according to any one of claims 1 to 7 and an organic solvent for dissolving the composition, wherein the concentration of the lignin-derived epoxy resin composition is 10 to 90% by weight. Varnish characterized by.   The varnish according to claim 12, wherein the solvent contains one kind selected from alcohols, ketones, ethers, aromatics and aliphatics.   A prepreg produced by impregnating and drying a varnish according to claim 12 or 13 in a fibrous base material.   A printed wiring board, wherein the prepreg according to claim 14 is laminated and integrated together with a conductor circuit.   An electronic apparatus comprising the cured prepreg according to claim 15 as an insulating material.   A molding material comprising one or more fillers blended in the lignin-derived epoxy resin composition according to claim 1.   An electronic apparatus using the cured product of the molding material according to claim 17.   A stator or rotor for a motor, wherein the cured product of the molding material according to claim 18 is used.

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