JP5750336B2 - Lignin resin composition, prepreg and composite structure - Google Patents

Description

  The present invention relates to a lignin resin composition, a prepreg, and a composite structure.

  Many wood-based waste materials (biomass) such as bark, thinned wood, and building waste have been disposed of so far. However, protection of the global environment is becoming an important issue, and from this point of view, the reuse and recycling of wood-based waste materials are being considered.

  Common woody main components are cellulose, hemicellulose and lignin. Among these, lignin contained at a ratio of about 30% has a structure containing abundant aromatic rings, phenolic hydroxyl groups, and alcoholic hydroxyl groups, and therefore, utilization as a resin raw material has been studied (for example, (See Patent Document 1).

  Thus, in order to utilize lignin as a resin raw material, it is necessary to isolate lignin from a wooden waste material.

  In Patent Document 1, a liquid phenol derivative is infiltrated into wood flour, lignin in wood flour is solvated with a phenol derivative, and then concentrated acid is added to dissolve the cellulose component, thereby dissolving lignin as a solvent. A method is disclosed in which a hydrated phenol derivative and a concentrated acid in which a cellulose component is dissolved are separated into two phases, and a lignin phenol derivative is extracted from the phenol derivative phase.

  Further, in Patent Document 1, a solvent in which a phenol derivative is dissolved in wood flour is infiltrated, and then the solvent is distilled off. Thereafter, concentrated acid is added to the remaining wood flour, thereby being solvated by the phenol derivative. A method for obtaining lignin is disclosed.

  However, since the lignin derivative produced by the method as described above has low meltability and solubility, when impregnating a substrate or the like, the impregnation property is poor, and it is brittle even if it is cross-linked and cured, and has mechanical properties. There is a problem that is low. For this reason, the lignin resin composition containing such a lignin derivative was unsuitable as a resin raw material.

JP 2001-261839 A

  The object of the present invention is to provide a lignin resin composition excellent in impregnation into a base material and excellent in mechanical properties after curing, and a prepreg capable of producing a composite structure excellent in mechanical properties (especially elongation at bending fracture). Another object of the present invention is to provide a composite structure having excellent mechanical properties.

Such an object is achieved by the present inventions (1) to (8) below.
(1) viewed contains lignin derived product obtained by decomposing biomass, a crosslinking agent, a
The number average molecular weight of the lignin derivative is less than 1000,
When the mass ratio of the lignin derivative having a molecular weight of less than 1000 in the total amount of the lignin derivative is A and the mass ratio of the lignin derivative having a molecular weight of 1000 or more is B, the percentage of B / (A + B) is less than 20% by mass. A lignin resin composition characterized by the above.

(2) in the total amount of the lignin derivative, the mass ratio of the molecular weight of 1000 or more 3000 less lignin derivative and B1, when the mass ratio of the molecular weight of 3000 or more lignin derivative was B2, B1> is B2, and, B1 The lignin resin composition according to the above (1) , wherein the percentage of / (A + B1 + B2) is 0.1% by mass or more and less than 10% by mass.

(3) The lignin resin composition according to (1) or (2) , wherein the lignin derivative has a molecular structure in which at least one of an ortho-position and a para-position of an aromatic ring is unsubstituted with respect to a hydroxyl group. .

(4) The lignin resin composition according to any one of (1) to (3) , wherein the cross-linking agent includes at least one of hexamethylenetetramine and a compound including two or more epoxy groups.

(5) The lignin resin composition according to any one of (1) to (4) , wherein the lignin derivative is a secondary derivative in which a reactive group is introduced into a lignin compound obtained by decomposing biomass. .
(6) The lignin resin composition according to (5) , wherein the reactive group is an epoxy group.

(7) A prepreg obtained by impregnating a base material with the lignin resin composition according to any one of (1) to (6 ) above.

(8) A composite structure obtained by curing the prepreg according to (7) .

  ADVANTAGE OF THE INVENTION According to this invention, the lignin resin composition which can manufacture the resin product excellent in the impregnation property to a base material and excellent in the mechanical characteristics after hardening is obtained.

  Furthermore, according to the present invention, a prepreg capable of producing a resin plate excellent in mechanical properties (particularly elongation at bending fracture) and a composite structure excellent in mechanical properties can be obtained.

  Hereinafter, the lignin resin composition, prepreg and composite structure of the present invention will be described in detail based on preferred embodiments.

<Lignin resin composition>
The lignin resin composition of the present invention comprises a lignin derivative obtained by decomposing biomass or a lignin secondary derivative in which a reactive group is introduced into this lignin derivative, and a crosslinking agent, and can be a resin raw material. Is.

(Lignin derivatives and lignin secondary derivatives)
First, a lignin derivative and a lignin secondary derivative will be described. The lignin derivative is obtained by decomposing biomass as described above.

  The biomass in the present invention is a plant containing lignin or a processed product of the plant. Examples of the plant include broad-leaved trees such as beech, birch and oak, conifers such as cedar, pine, and oak, grasses such as bamboo and rice straw, and coconut shells.

  A lignin derivative is a compound having a phenol derivative as a unit structure. Since this unit structure has a chemically and biologically stable carbon-carbon bond or carbon-oxygen-carbon bond, it is less susceptible to chemical degradation and biological degradation. For this reason, a lignin derivative is useful as a resin raw material.

  Specific examples of the lignin derivative include a guaiacylpropane structure represented by the following formula (1), a syringylpropane structure represented by the following formula (2), and a 4-hydroxyphenylpropane structure represented by the following formula (3). Can be mentioned.

  Moreover, the lignin derivative in the present invention is preferably one in which at least one of the ortho-position and para-position of the aromatic ring is unsubstituted with respect to the hydroxyl group. Such a lignin derivative is excellent in reactivity because it contains a large number of reaction sites where a curing agent acts due to electrophilic substitution reaction on the aromatic ring and steric hindrance can be reduced in the reaction with a hydroxyl group.

  Here, the lignin resin composition of the present invention contains a lignin derivative having a number average molecular weight of less than 1000. The present inventor highly improves the reactivity (curability) and meltability or solubility of the lignin resin composition by adjusting the number average molecular weight of the lignin derivative in the lignin resin composition within the above range. The inventors have found that they can be compatible, and have completed the present invention. A lignin resin composition containing such a lignin derivative is highly useful as a resin raw material because it has a high level of important properties as a resin raw material that has been difficult to achieve together. In addition, since the lignin resin composition of the present invention has high fluidity, voids (voids) are generated in the molded body produced using the resin composition, and the smoothness of the molded body decreases. Can be prevented.

  The number average molecular weight of the lignin derivative is measured by gel permeation chromatography (GPC) analysis and determined as a value in terms of polystyrene.

  When the number average molecular weight is not less than the above upper limit, the softening point of the lignin derivative is too high and the meltability or solubility is lowered, and the number of reaction sites is too small and the reactivity is lowered.

  The number average molecular weight of the lignin derivative is preferably 200 or more and less than 900, more preferably 300 or more and less than 800.

  On the other hand, the lignin resin composition of the present invention may contain a low molecular weight lignin derivative as described above, but may contain a higher molecular weight than that.

  Specifically, when the mass ratio of the lignin derivative having a molecular weight of less than 1000 in the total amount of the lignin derivative is A and the mass ratio of the lignin derivative having a molecular weight of 1000 or more is B, the percentage of B / (A + B) is 20% by mass. It is preferably less than 15%, more preferably less than 15% by mass. In this way, in addition to making the number average molecular weight less than 1000, and suppressing the ratio of B within the above range, the lignin derivative is more highly compatible with its reactivity (curability) and meltability or solubility. To be. Therefore, the lignin resin composition has excellent impregnation properties to the base material and excellent mechanical properties after curing.

  Furthermore, when the mass ratio of the lignin derivative having a molecular weight of 1000 or more and less than 3000 is B1, and the mass ratio of the lignin derivative having a molecular weight of 3000 or more is B2, in the total amount of the lignin derivative, B1> B2, and B1 / The percentage of (A + B1 + B2) is preferably 0.1% by mass or more and less than 10% by mass, and more preferably 0.1% by mass or more and less than 8% by mass. In the lignin derivative, the number average molecular weight is less than 1000, and in addition, the ratio of those having a molecular weight of 1000 or more and less than 3000 is within the above range, so that the lignin derivative can be further reduced without lowering the meltability or solubility. It becomes highly reactive. The reason for this is not clear, but the lignin derivative with a relatively low molecular weight is slightly mixed with a lignin derivative with a slightly higher molecular weight, so there is little effect on the meltability and solubility. This is considered to be due to the effect that the reactivity is remarkably increased.

  The percentage of B2 / B1 is preferably 10% by mass or more and 70% by mass or less, and more preferably 15% by mass or more and 50% by mass or less. As a result, the abundance ratio between the lignin derivative having a slightly higher molecular weight and the lignin derivative having a particularly large molecular weight is optimized, and the above effects become more remarkable.

In addition, the lignin derivative in the present invention, when subjected to ¹ H-NMR analysis, in the obtained chemical shift spectrum, the integrated value of the peak attributed to the aromatic proton is the integrated value of the peak attributed to the aliphatic proton. Is preferably about 15 to 50%, more preferably about 15 to 45%, still more preferably about 20 to 40%, and particularly preferably about 20 to 35%. Thereby, the reactivity which contributes to the mechanical characteristic of the cured resin of a lignin derivative and the meltability which contributes to the impregnation property to a base material etc., or the solubility to a solvent can be made compatible more highly. As a result, the base material or the like can be impregnated reliably while maintaining the reactivity of the lignin derivative, so that the lignin resin composition containing the lignin derivative can be effectively used as a resin raw material. That is, a lignin resin composition suitable for a resin raw material is obtained.

  When the ratio falls below the lower limit, a reaction site that causes a crosslinking reaction by the action of a general curing agent or a reaction site for introducing a reactive group is substituted with an aliphatic group, and the crosslinking reaction point is Therefore, when a lignin resin composition containing a lignin derivative is used as a resin raw material, the physical properties of the cured product may be reduced. On the other hand, when the ratio exceeds the upper limit, the meltability of the lignin derivative or the solubility in the solvent is remarkably reduced, and when used as a resin raw material, the moldability can be reduced and used as a resin raw material. May be difficult.

In addition, since aromatic protons and aliphatic protons generate peaks at distant positions in the chemical shift spectrum of ¹ H-NMR analysis, peaks can be separated, and peak identification and integral calculation are performed. be able to.

  Specifically, when tetramethylsilane is used as a reference substance for analysis, generally, a peak attributed to an aromatic proton is located in the vicinity of 6 to 8 ppm. In addition, the peak attributed to the aliphatic proton is located in the vicinity of 0.5 to 5 ppm.

  On the other hand, the lignin secondary derivative in the present invention is obtained by introducing a reactive group into the lignin derivative in the present invention as described above. Since such a lignin secondary derivative has various reactive groups, it can be crosslinked at a high density and is useful as a resin raw material.

  The reactive group possessed by the lignin secondary derivative is a reactive atomic group, is self-reactive, and can react with two or more of the same reactive groups, or react with other functional groups. There is no particular limitation as long as it can be obtained. Specific examples include an epoxy group, a methylol group, a vinyl group having a carbon-carbon unsaturated bond, an ethynyl group, a maleimide group, a cyanate group, and an isocyanate group. Moreover, an epoxy group is preferably used. The lignin secondary derivative having an epoxy group is useful as a resin raw material that can replace a general epoxy resin.

(Crosslinking agent)
Next, the crosslinking agent will be described.

  The lignin resin composition of the present invention contains at least one of the above-described lignin derivative and lignin secondary derivative and a crosslinking agent. The lignin derivative and the lignin secondary derivative are cured by a crosslinking reaction caused by the action of the crosslinking agent. As a result, a resin product can be produced from the lignin resin composition.

  The crosslinking agent is not particularly limited as long as it causes a crosslinking reaction in the phenolic hydroxyl group or reactive group of the lignin derivative and lignin secondary derivative. In addition, since the lignin resin composition contains both the lignin derivative and the lignin secondary derivative, both the phenolic hydroxyl group and the reactive group serve as reaction sites, so that the crosslinking density or crosslinking speed is improved, and the resin raw material As useful as.

  Specifically, as a crosslinking agent that causes a crosslinking reaction to a phenolic hydroxyl group, for example, an orthocresol novolac epoxy resin, an epoxy resin such as a bisphenol A type epoxy resin, a urethane resin such as hexamethylene diisocyanate, toluene diisocyanate, Compounds that can be cross-linked by electrophilic substitution on the aromatic ring of lignin derivatives include aldehydes such as formaldehyde, acetaldehyde and paraformaldehyde, aldehyde sources such as polyoxymethylene, hexamethylenetetramine, and resol-type phenol. Examples of the conventional phenol resin such as a resin include a known crosslinking agent and a compound that can be crosslinked by electrophilic substitution reaction on the aromatic ring of the lignin derivative. In view of reactivity and availability, a crosslinking agent containing at least one of a compound containing two or more hexamethylenetetramines and epoxy groups is preferably used.

  On the other hand, the cross-linking agent that causes a cross-linking reaction to the reactive group of the lignin secondary derivative may be any cross-linking agent that reacts with the reactive group or has a self-crosslinking reactive group. When the reactive group in the lignin secondary derivative is an epoxy group, for example, a phenol resin such as a novolak type phenol resin, a lignin compound having a phenolic hydroxyl group, diethylenetriamine, m-xylylenediamine, N-aminoethyl General epoxy compounds such as amine compounds such as piperazine, acid anhydrides such as phthalic anhydride, succinic anhydride and maleic anhydride, dicyandiamide, guanidines, 2-methylimidazole and 2-ethyl-4-methylimidazole Examples include a curing agent for resin.

  Examples of the crosslinking agent having a self-crosslinkable reactive group include imidazoles such as 2-methylimidazole and 2-ethyl-4-methylimidazole, 1,8-diazabicyclo (5,4,0) undecene. Cationic polymerization initiators such as anionic polymerization initiators such as -7, sulfonium salts such as triphenylsulfonium hexafluorophosphate and diphenylsulfonium tetrafluoroborate, and diazonium salts such as phenyldiazonium hexafluorophosphate and phenyldiazonium tetrafluoroborate An agent etc. are mentioned, Among these, the 1 type, or 2 or more types of mixture is used. Among these, lignin compounds are preferably used from the viewpoint of reactivity and the like.

  Further, when the reactive group in the lignin secondary derivative is an isocyanate group, examples of the crosslinking agent include general curing agents for isocyanate resins such as phenol resins, lignin degradation products, polyvinyl alcohol, and polyamine compounds. One or a mixture of two or more of these is used.

  When the reactive group in the lignin secondary derivative is a vinyl group, examples of the crosslinking agent include anionic polymerization initiators such as butyl lithium and sodium ethoxide, azobisisobutyronitrile (AIBN), Examples thereof include polymerization initiators of general vinyl group-containing compounds such as radical polymerization initiators such as benzoyl peroxide (BPO), and one or a mixture of two or more of these are used.

  Further, when the reactive group in the lignin secondary derivative is an ethynyl group, as a crosslinking agent, for example, a polymerization catalyst of a general ethynyl group-containing compound such as molybdenum pentachloride, tungsten pentachloride, norbornadiene rhodium chloride dimer or the like can be used. Among them, one or a mixture of two or more of these is used.

  In addition, when the reactive group in the lignin secondary derivative is a maleimide group, examples of the crosslinking agent include polymerization of general maleimide group-containing compounds such as peroxides such as BPO and the aforementioned anionic polymerization initiators. An initiator is mentioned, The mixture of 1 type, or 2 or more types of these is used.

  Further, when the reactive group in the lignin secondary derivative is a cyanate group, examples of the crosslinking agent include polymerization catalysts for general cyanate group-containing compounds such as metal catalysts such as cobalt naphthenate, and the like. Among them, one kind or a mixture of two or more kinds is used.

  In the lignin resin composition, the content of the lignin derivative or the lignin secondary derivative is preferably 40 to 95% by mass, and more preferably 50 to 90% by mass. Moreover, it is preferable that content of a crosslinking agent is 5-60 mass%, and it is more preferable that it is 10-50 mass%.

(Other ingredients)
In addition to the above components, the lignin resin composition of the present invention may contain, as necessary, an alkali metal salt such as sodium methoxy, t-butoxy potassium, an alkaline earth metal salt such as calcium acetate, Na ₂ O, K _A hardening accelerator such as an alkali metal oxide such as ₂ O and an alkaline earth metal oxide such as CaO or BaO may be included.

  In particular, when a lignin secondary derivative having an epoxy group as a reactive group is included, for example, imidazoles such as 2-methylimidazole and 2-ethyl-4-methylimidazole, 1,8-diazabicyclo (5, 4,0) undecene-7, tris (dimethylaminomethyl) phenol, tertiary amines such as benzyldimethylamine, triphenylphosphine, tetra-n-butylphosphonium tetraphenylborate and the like may be contained.

  Moreover, when the lignin secondary derivative which has a methylol group, a vinyl group, an ethynyl group, a maleimide group, a cyanate group etc. as a reactive group is included, the said polymerization initiator may be included, for example.

Furthermore, the additive mentioned later may be included as other components.
Examples of such additives include silane coupling agents such as epoxy silane, mercapto silane, amino silane, alkyl silane, ureido silane, and vinyl silane, titanate coupling agents, aluminum coupling agents, and aluminum / zirconium coupling agents. Various coupling agents, colorants such as carbon black, bengara, polyethylene wax, higher fatty acid esters, fatty acid amides, ketones and amines, synthetic waxes such as hydrogenated oils, natural waxes such as paraffin wax and montan wax, Higher fatty acids such as stearic acid and zinc stearate and metal salts thereof, mold release agents such as paraffin, silicone oil, low stress components such as silicone rubber, antimony trioxide, aluminum hydroxide, Examples include magnesium oxide, zinc borate, zinc molybdate, flame retardants such as phosphazene, inorganic ion exchangers such as bismuth oxide hydrate, and a combination of one or more of these is used. It is done.

  Moreover, when a lignin resin composition contains a mold release agent, it is preferable that content of a mold release agent is 0.01-10 mass parts with respect to 100 mass parts of lignin derivatives or a lignin secondary derivative. It is more preferably 1 to 5 parts by mass. In addition, when the content of the release agent is less than the above, when the lignin resin composition is filled in a mold and molded, the mold release property may be insufficient, whereas the content of the release agent If the value exceeds the upper limit, the curability of the lignin resin composition may be reduced.

<Prepreg>
Next, the prepreg of this invention manufactured using the lignin resin composition mentioned above is demonstrated.

  The prepreg of the present invention is obtained by impregnating a base material with the lignin resin composition of the present invention.

  Examples of the base material include glass fiber base materials such as glass woven fabric and glass non-woven fabric, paper materials such as kraft paper and linter paper, cotton fibers, hemp fibers, aramid fibers, polyester fibers, acrylic fibers, etc. Examples include organic synthetic fiber base materials composed of woven or non-woven fabrics such as natural fibers or synthetic fibers, inorganic fiber base materials composed of woven or non-woven fabrics such as metal fibers, carbon fibers and mineral fibers, or mats thereof. . In addition, you may make it use the raw material fiber of these base materials individually or in mixture.

  Such a prepreg is manufactured, for example, by impregnating a base material with a lignin resin composition and then drying. At this time, the lignin resin composition is used as a varnish dissolved in an organic solvent, but may be used by a method such as melt impregnation in a solvent-free powder state.

  Examples of the method of impregnating the base material with the lignin resin composition include a method of immersing the base material in the varnish, a method of applying the varnish with various coaters, and a method of spraying the varnish by spraying.

  In addition, in the prepreg obtained by drying, it is preferable that 80 mass% or more of the organic solvent used for the varnish is volatilized.

  In the above drying, the drying conditions are not particularly limited, but the drying temperature is preferably about 80 to 180 ° C., and the drying time is freely selected according to the desired prepreg characteristics in consideration of the gelation time of the varnish. The

  Further, the resin impregnation rate in the prepreg is represented by the ratio of the total mass of the lignin derivative and the lignin secondary derivative and the crosslinking agent with respect to the total mass of the prepreg, and is preferably about 30 to 80% by mass, It is more preferable that the amount is about 70% by mass. These ratios are appropriately adjusted according to the target performance of the prepreg, the thickness of the insulating layer in the substrate obtained by pressing the prepreg, and the like. The amount of impregnation of the varnish is preferably set so that the solid content in the varnish occupies 35 to 75% by mass with respect to the total amount of the solid content in the varnish and the base material.

<Resin plate>
Next, the resin plate (the composite structure of the present invention) will be described.

  The resin plate is manufactured by curing a laminate formed by laminating one or two or more prepregs as described above.

  Specifically, it is produced by curing a lignin derivative and a lignin secondary derivative while forming a prepreg or a laminate thereof into a substrate by heat and pressure molding.

  The temperature at the time of heating and pressing is preferably about 100 to 280 ° C, more preferably about 120 to 250 ° C. Further, the pressure is preferably about 0.5 to 20 MPa, more preferably about 1 to 10 MPa.

  Moreover, if it is such a method, it can form in arbitrary shapes with the metal mold | die at the time of shaping | molding, and the obtained resin board (composite structure) is electric / electronic materials, structural materials, such as a printed circuit board. It is preferably used as a building material or an insulating material.

  As an electric / electronic material application such as the printed circuit board, a metal foil is laminated by laminating a metal foil on one or both sides of a prepreg or a laminate thereof before heat and pressure molding, and heat and pressure molding these. A substrate (metal-clad laminate) can be manufactured. Furthermore, in this metal-clad substrate, a printed wiring board provided with a circuit can be manufactured by processing the metal layer into a predetermined shape.

  As the metal foil, copper foil or aluminum foil is generally used. Moreover, the average thickness shall be about 5-200 micrometers.

  The metal foil includes an intermediate layer made of a metal material such as nickel, nickel-phosphorus, nickel-tin alloy, nickel-iron alloy, lead, lead-tin alloy, and an average thickness provided on both surfaces thereof. A composite foil having a three-layer structure having a copper layer having a thickness of 0.5 to 15 μm and a copper layer having an average thickness of 10 to 300 μm, or a two-layer structure composite foil in which an aluminum foil and a copper foil are combined is used. Also good.

  Such a resin plate is applied to a substrate for electric / electronic materials such as a printed wiring board, a mother board, and a semiconductor plastic package.

  On the other hand, applications other than electrical / electronic material substrates include structural materials such as automobile interior materials, building materials such as interior materials for houses and office buildings, and insulating materials used for switchboards.

<Method for producing lignin resin composition>
Next, a method for producing the lignin resin composition of the present invention will be described.

  In this production method, [1] biomass is adjusted to a certain size, then placed in the presence of a mixed solvent containing water and an aprotic polar solvent, and decomposed under high temperature and high pressure. From the decomposition step of [2], the second decomposition step of decomposing the soluble part obtained by the first decomposition step under high temperature and high pressure, and [3] the processed product obtained by the second decomposition step A distillation step of distilling off the aprotic polar solvent to obtain a lignin derivative as an insoluble matter in the residue, [4] a reactive group introduction step of introducing a reactive group into the lignin derivative as necessary, [ 5] A mixing step of mixing a lignin derivative and a crosslinking agent to obtain a lignin resin composition.

Hereinafter, each process will be described sequentially.
[1] First decomposition step First, biomass is placed in the presence of a solvent. Although what was mentioned above is mentioned as biomass, Although the shape is not specifically limited, It is set as a block shape, a chip shape, a powder form etc.

  Moreover, it is preferable that the magnitude | size of the biomass used for this invention is about 100 micrometers-1 cm, and it is more preferable that it is about 200-1000 micrometers. By using biomass of such a size, it is possible to improve the dispersibility of the biomass in the liquid and to efficiently perform the biomass decomposition treatment.

  As the solvent used in the first decomposition step, water and various organic solvents are used, and a mixed solvent of water and an aprotic polar solvent is particularly preferably used. Among these, as water, for example, ultrapure water, pure water, distilled water, ion exchange water, or the like is used.

  On the other hand, examples of the aprotic polar solvent include methyl ethyl ketone, ketones such as acetone, cyclic ethers such as tetrahydrofuran and dioxane, nitriles such as acetonitrile, N, N-dimethylformamide, N, N-dimethyl. Examples include amides such as acetamide and n-methylpyrrolidone, alkyl halides such as methylene chloride and chloroform, and one or a combination of two or more of these is used. Among these, at least one of ketones and cyclic ethers is preferably used from the viewpoint of biomass decomposition efficiency and the like.

  In addition, since the aprotic polar solvent is compatible with water, the mixed solvent has high homogeneity and can be efficiently decomposed.

  Here, the aprotic polar solvent preferably has a boiling point lower than that of water. By using such an aprotic polar solvent, only the aprotic polar solvent can be easily distilled off from the mixed solvent with water, and the later-described distillation step can be easily performed.

  In this case, the difference in boiling point between water and the aprotic polar solvent is not particularly limited, but is preferably about 5 to 60 ° C, more preferably about 10 to 50 ° C, and about 20 to 50 ° C. More preferably. If the difference in boiling points is within the above range, the lignin derivative that is finally isolated can be reliably separated from water and the aprotic polar solvent in the distillation step described later while maintaining compatibility. Can be highly purified.

  As a usage-amount of a solvent, it is so good that it is large with respect to biomass, However, Preferably it is about 1-20 mass times with respect to biomass, and it is more preferable that it is about 2-10 mass times. As a result, the amount of solvent necessary and sufficient for the biomass decomposition treatment is obtained.

  Further, the mixing ratio of water and aprotic polar solvent in the mixed solvent is not particularly limited, but when the amount of water is 1, the amount of aprotic polar solvent is about 0.2 to 5 by mass ratio. The ratio is preferably about 0.3 to 3, and more preferably about 0.3 to 3. Thereby, a lignin derivative can be efficiently and reliably isolated from biomass.

  Further, the mixed solvent may contain other solvents in addition to water and the aprotic polar solvent. The content of the other solvent in the mixed solvent is less than each of water and the aprotic polar solvent, and is 10% by mass or less of the mixed solvent, and is preferably 5% by mass or less.

  Examples of the other solvent include alcohols such as methanol and ethanol, phenols such as phenol and cresol, and the like, or a combination of one or more of these is used.

  Next, the biomass in the presence of the solvent is decomposed under high temperature and pressure. Thereby, biomass is decomposed into lignin, cellulose, hemicellulose, and other reactants.

  In the generation of a high temperature and high pressure environment, for example, a pressure vessel such as an autoclave is used. Moreover, as this pressure vessel, what is equipped with a heating means and a stirring means is used preferably, and it is preferable to stir biomass under high temperature and pressure. Moreover, you may provide the means to pressurize independently from the factor which influences pressure, such as the temperature in a container, as needed. Examples of such means include means for introducing an inert gas such as argon gas into the container.

  In addition, in the production | generation of high temperature / high pressure environment, a continuous type (flow type) apparatus other than a batch type apparatus is also used. In particular, when the object to be treated is a liquid and contains a dispersoid, if the particle size is extremely small, continuous treatment is possible and the treatment efficiency can be improved, so that a continuous apparatus is preferably used.

  The treatment condition in the first decomposition step is preferably a treatment temperature of 150 to 350 ° C, and more preferably 180 to 300 ° C. When the treatment temperature is within the above range, the molecular weight of the lignin derivative obtained after decomposition can achieve both reactivity and meltability or solubility. In addition, when processing temperature is less than the said lower limit, the molecular weight of a lignin derivative becomes higher than necessary, and there exists a possibility that it may be inferior to solubility and a meltability. On the other hand, when the treatment temperature exceeds the upper limit, the molecular weight of the lignin derivative becomes unnecessarily low, and the reactivity may decrease when used as a resin raw material.

  Moreover, it is preferable that the processing time in a decomposition process is 480 minutes or less, and it is more preferable that it is 30 to 120 minutes. If the treatment time is within the above range, the ratio of aromatic protons and aliphatic protons of the lignin derivative obtained after decomposition is an appropriate value, and optimization is performed from the viewpoint of compatibility between reactivity and meltability or solubility. Can do.

  Furthermore, the pressure in the decomposition treatment is preferably 0.1 to 12 MPa, and more preferably 0.2 to 10 MPa. When the pressure is within the above range, the biomass decomposition efficiency can be significantly increased, and the processing time can be shortened accordingly. If necessary, the pressure inside the pressure vessel may be increased with argon gas or the like to increase the pressure.

  Moreover, you may make it add the catalyst and oxidizing agent which accelerate | stimulate a decomposition process as needed in a solvent. Examples of the catalyst include inorganic bases such as sodium carbonate, inorganic acids such as acetic acid and formic acid, and examples of the oxidizing agent include hydrogen peroxide. The amount of the catalyst and the oxidizing agent added is preferably about 0.1 to 10% by mass, more preferably about 0.5 to 5% by mass in the concentration in the solvent.

  Furthermore, as a pretreatment for the decomposition treatment, it is preferable to perform a step of sufficiently stirring the biomass and the solvent so as to make them both fit. Thereby, the decomposition of biomass can be particularly optimized.

  In addition, as stirring temperature, it is preferable that it is about 0-150 degreeC, and it is more preferable that it is about 10-130 degreeC.

  Moreover, as stirring time, it is preferable that it is about 1 to 120 minutes, and it is more preferable that it is about 5 to 60 minutes.

  Further, examples of the stirring method include various mills such as a ball mill and a bead mill, a method using a stirrer equipped with a stirring blade, a method using water flow stirring using a homogenizer, a jet pump, and the like.

  The solvent used in the first decomposition step is preferably used in a subcritical or supercritical state (condition). It is considered that the solvent in the subcritical or supercritical state contributes to the acceleration of the biomass decomposition process. For this reason, the efficiency of a decomposition process can be improved more, the manufacturing cost of a lignin derivative can be reduced, and the manufacturing process can be simplified.

  Furthermore, since the solvent used in the first decomposition step is a mixed solvent of water and an aprotic polar solvent as described above, both water and the aprotic polar solvent are in a subcritical or supercritical state. However, even if either one is in a subcritical or supercritical state, a sufficient effect can be obtained.

  As an example, the critical temperature of water is about 374 ° C., the critical pressure is about 22.1 MPa, the critical temperature of acetonitrile is about 272 ° C., the critical pressure is about 4.8 MPa, and the critical temperature of acetone is about 235 ° C. The critical pressure is about 4.7 MPa at ° C.

  Moreover, in the processed material obtained by this process, at least 1 sort (s) of cellulose, a cellulose derivative, and a cellulose degradation product is contained in high concentration as an insoluble part. For this reason, the cellulose and the cellulose-derived substance can be separated and manufactured by collecting the insoluble part. The insoluble part can be recovered by a method such as filtration.

[2] Second decomposition step Next, the processed product obtained in the first decomposition step is separated into a soluble portion and an insoluble portion by filtration. And the obtained soluble part is decomposed | disassembled under high temperature and pressure. Thereby, the processed product obtained by the 1st decomposition process is made more low molecular.

  The high-temperature and high-pressure environment used in this step is also generated in the same manner as in the first decomposition step, and for example, an autoclave is used.

  On the other hand, about the process conditions in a 2nd decomposition process, it is preferable that process temperature is higher than the process temperature in a 1st decomposition process. In this way, by sequentially performing the first decomposition step that is processed at a relatively low temperature and the second decomposition step that is processed at a relatively high temperature, the processed product is decomposed into a low-molecular-weight product and decomposed. Variation in molecular weight of the subsequent lignin derivative can be further reduced. As a result, the number average molecular weight of the lignin derivative can be suppressed within the above range, the fluidity of the lignin resin composition can be improved, and voids (voids) are generated in the molded product produced using the resin composition. Or the smoothness of the molded body can be prevented from being lowered.

  In addition, by performing the second decomposition step subsequent to the first decomposition step, unit structures of the polymer bodies in which the lignin unit structures (phenylpropane structures) are bonded to each other in the second decomposition step. The β-O-4 bond that is mainly connected can be efficiently cleaved and cleaved. Thereby, lower molecular weight and uniform molecular weight can be achieved.

As described above, the treatment temperature in the second decomposition step is preferably higher than the treatment temperature in the first decomposition step, but the temperature difference is preferably about 30 to 150 ° C, and 40 to 120 ° C. More preferably, it is about 50-100 degreeC. By providing such a temperature difference, in the first decomposition step, the unit structures in the lignin are not cut as much as possible, and the lignin polymer in the biomass, cellulose, hemicellulose and the like are separated from each other, and thereafter In the second decomposition step, necessary and sufficient thermal energy is applied to break the aforementioned β-O-4 bond. As a result, a lignin derivative having both low molecular weight and high curability can be obtained.
The second decomposition step may be performed as necessary, and may be a single decomposition step.

[3] Distillation step Next, the aprotic polar solvent is distilled off from the treated product obtained in the second decomposition step. Thereby, the residue obtained by distilling off the aprotic polar solvent is separated into an aqueous phase and an insoluble matter. This insoluble matter is a lignin derivative. Therefore, a lignin derivative can be obtained by recovering insolubles from the residue. A method such as filtration, heat dehydration, or vacuum dehydration is used to recover the insoluble matter. In this method, the lignin derivative can be finally recovered as a solid substance. For this reason, compared with the case where it collect | recovers as a solute of a solution, collection | recovery operation | work is easy and it becomes possible to raise the manufacturing efficiency of a lignin derivative dramatically.
By the above method, a lignin derivative can be produced with high yield.

  Moreover, in the processed material obtained by this process, at least 1 sort (s) of hemicellulose, a hemicellulose derivative, and a hemicellulose degradation product is contained in high concentration as a soluble part. For this reason, by recovering the soluble part, the aforementioned hemicellulose or a material derived from hemicellulose can be separated and manufactured. The soluble part can be recovered by removing the water after filtration by a method such as heat dehydration or vacuum dehydration.

[4] Reactive group introduction step As a method for introducing a reactive group into the produced lignin derivative, for example, a method of mixing a lignin derivative and a compound containing a reactive group is used. And after mixing, a reactive group is introduce | transduced into a lignin derivative by adding a catalyst etc. as needed.

  Specifically, when introducing an epoxy group, it can be introduced by mixing a lignin derivative, epichlorohydrin and a solvent, and adding a base catalyst such as sodium hydroxide to the mixture under reflux under reduced pressure.

  In addition, when introducing a methylol group, it can be introduced by mixing a lignin derivative and an aldehyde such as formaldehyde, and adding an alkaline catalyst such as sodium hydroxide, potassium hydroxide, ammonia or the like, followed by heating reaction. .

  In addition, when introducing a vinyl group, a lignin derivative, a halogen compound containing a vinyl group such as an allyl halide or a vinylbenzyl halide, and a solvent are mixed, and a base catalyst such as sodium hydroxide is added to the mixture under heating and stirring. Can be introduced.

  In addition, when introducing an ethynyl group, a lignin derivative, a halogen compound containing an ethynyl group such as a propargyl halide or a phenylacetylene halide, and a solvent are mixed, and a base catalyst such as sodium hydroxide is added to the mixture with heating and stirring. Can be introduced.

  Moreover, when introduce | transducing a cyanate group, it can introduce | transduce by mixing a lignin derivative, halogenated cyanate, and a solvent, and adding a base catalyst, such as sodium hydroxide, to this under heating stirring.

  When introducing a maleimide group, a lignin derivative and parachloronitrobenzene are mixed. As a result, the maleimide group reacts with the phenolic hydroxyl group of the lignin derivative to obtain a polynitrated lignin bonded via an ether bond. Subsequently, polynitrated lignin is reduced to be converted to polyaminated lignin, and further reacted with maleic anhydride to obtain a lignin secondary derivative having a maleimide group introduced.

Moreover, when introduce | transducing an isocyanate group, the hydroxyl group in a lignin derivative is converted into a carboxyl group by mixing a lignin derivative and maleic anhydride. Thereafter, the mixture is heated in the presence of diphenyl phosphate azide to obtain a lignin secondary derivative having an introduced isocyanate group.
A lignin derivative and a lignin secondary derivative can be produced as described above.

[5] Mixing Step Next, at least one of the lignin derivative and the lignin secondary derivative, the crosslinking agent, and other components added as necessary are uniformly mixed by a mixer. Thereby, a lignin resin composition is obtained. In addition, when mixing, it is blended in a powder state, or diluted and mixed in a solvent, using a hot plate, a kneader such as a pressure kneader, a roll, a kneader, a twin screw extruder, etc. Heat melting and fusion may be performed at a temperature lower than the temperature at which the mixture is cured. Although the specific heating temperature at the time of heating is a little different depending on the composition to be selected, it is preferably about 50 to 100 ° C.

  Although the present invention has been described above, the present invention is not limited to this. For example, the prepreg and the composite structure may be added with any constituent.

Next, specific examples of the present invention will be described.
1. Manufacture of laminate (Sample No. 1)
<Production of lignin derivative>
(First decomposition step)
100 g of cedar wood flour (60 mesh under) and 400 g of a mixed solvent obtained by mixing pure water and acetone at a mass ratio of 1: 1 are introduced into a 1 L autoclave and the contents are stirred while stirring at 300 rpm. As a treatment, the mixture was stirred at room temperature for 15 minutes to sufficiently blend the cedar wood powder and the mixed solvent, and then treated at 200 ° C. and saturated vapor pressure for 60 minutes to decompose the cedar wood powder.

(Second decomposition step)
About the decomposition product obtained by the 1st decomposition | disassembly process, the soluble part and the insoluble part were isolate | separated by filtration. Subsequently, the soluble part obtained was subjected to a decomposition process by subjecting it to a continuous decomposition apparatus. The processing conditions in the second decomposition step were a processing temperature of 300 ° C., a processing time of 8 minutes, and a pressure of 20 MPa.

(Distillation step)
Acetone was distilled off from the treated product obtained in the second decomposition step. And the soluble part and the insoluble part were isolate | separated by filtration about the residue. Then, the lignin derivative was obtained by drying an insoluble part.

About what was obtained here, when it used for the ¹ H-NMR analysis, in the spectrum of the chemical shift which used tetramethylsilane as the reference substance of 0 ppm, a plurality of peaks attributed to the aromatic proton at 6 to 8 ppm are 0 A plurality of peaks attributed to aliphatic protons were observed at 5 to 3 ppm.

  Therefore, for each detected peak, the integral value of the plurality of peaks belonging to the aliphatic proton was calculated, where the integral value of the plurality of peaks belonging to the aromatic proton was set to 1. The calculation results are shown in Table 1.

  The molecular weight of the lignin derivative obtained above was measured by gel permeation chromatography in terms of polystyrene using tetrahydrofuran as an eluent. The measured number average molecular weight (Mn) is shown in Table 1.

<Manufacture of lignin resin composition>
Next, 10 parts by mass of hexamethylenetetramine was added to 90 parts by mass of the obtained lignin derivative at room temperature to obtain a lignin resin composition.

<Manufacture of varnish for substrate impregnation>
And the lignin resin composition obtained above was diluted with methanol, and the resin varnish for base-material impregnation with a resin content of 50 mass% was obtained.

<Manufacture of prepreg and resin plate>
Next, the varnish for impregnating the base material obtained above with a dip coater device with respect to kraft paper (basis weight 135 g / m ² ) so that the resin impregnation rate is 55 mass% (ratio to the whole prepreg). It was coated and then dried at 150 ° C. for 1 minute to obtain a prepreg. Eight prepregs thus produced were stacked and subjected to heat and pressure molding at 150 ° C. and 10 MPa for 30 minutes. Thereby, a laminated plate (resin plate) having an average thickness of 1.6 mm was obtained.

(Sample Nos. 2 to 13)
Except for changing the type of biomass, solvent, temperature, pressure, and time in the decomposition treatment as shown in Table 1, sample No. A lignin derivative was obtained in the same manner as in Example 1, and a laminate was obtained.

In addition, each sample No. For the lignin derivative, the chemical shift spectrum by ¹ H-NMR analysis was obtained, and the ratio of the integrated value of the plurality of peaks belonging to the aromatic proton to the integrated value of the plurality of peaks belonging to the aliphatic proton is shown in Table 1. Indicated.

  Further, each sample No. The number average molecular weight (Mn) of the lignin derivative was measured and shown in Table 1.

(Sample No. 14)
<Production of lignin derivative>
50 g of cedar wood flour was placed in a 2 L beaker, a methanol solution of p-cresol (containing 3 mol times of phenol derivative per lignin constituent unit) was added, and the mixture was stirred with a glass rod and allowed to stand for 24 hours. Thereafter, methanol was completely distilled off to obtain p-cresol sorption wood flour. To this wood flour, 500 ml of 72% by weight sulfuric acid was added and stirred vigorously at 30 ° C. for 1 hour, and then the mixture was poured into a large excess of water, the insoluble matter was recovered, deacidified and dried to give a lignin derivative. Got.

About the obtained lignin derivative, the spectrum of the chemical shift by ¹ H-NMR analysis was acquired, and the ratio of the integrated value of the plurality of peaks attributed to the aromatic proton to the integrated value of the plurality of peaks attributed to the aliphatic proton was expressed. It was shown in 2.
The number average molecular weight (Mn) of the obtained lignin derivative was measured and shown in Table 2.

<Manufacture of lignin resin composition>
Next, 10 parts by mass of hexamethylenetetramine was added to 90 parts by mass of the obtained lignin derivative at room temperature to obtain a lignin resin composition.

<Manufacture of varnish for substrate impregnation>
Next, the lignin resin composition obtained above was diluted with methanol to obtain a resin varnish for substrate impregnation having a resin content of 50% by mass.

<Manufacture of prepreg and resin plate>
Next, the resin varnish for impregnating the base material obtained above was applied to kraft paper with a dip coater so that the resin content was 55% by mass (ratio to the whole prepreg), and then 150 ° C. And dried for 1 minute to obtain a prepreg. Eight prepregs thus produced were stacked and subjected to heat and pressure molding at 150 ° C. and 10 MPa for 30 minutes. However, the laminated board could not be formed due to insufficient melting.

(Sample No. 15)
Sample No. was changed except that the type of biomass was changed as shown in Table 2. In the same manner as in the case of 14, a lignin derivative was obtained and a prepreg was obtained. However, the laminated sheet could not be formed due to insufficient melting during molding.

(Sample No. 16-21)
Except for changing the type of biomass, the solvent, the temperature, the pressure and the time in the decomposition treatment as shown in Table 2, sample No. A lignin derivative was obtained in the same manner as in Example 1, and a laminate was obtained.

In addition, each sample No. The chemical shift spectrum obtained by ¹ H-NMR analysis was obtained for the lignin derivative, and the ratio of the integrated value of the plurality of peaks belonging to the aromatic proton to the integrated value of the plurality of peaks belonging to the aliphatic proton is shown in Table 2. Indicated.

  Further, each sample No. The number average molecular weight (Mn) of the lignin derivative was measured and shown in Table 2.

(Sample No. 22)
Except that the epoxy group was introduced into the lignin derivative by the following steps to produce a lignin secondary derivative and a laminate was produced using this, sample No. Same as 1.

<Production of secondary lignin derivative>
First, in a three-necked flask equipped with a stirrer and a cooling pipe, sample No. 25.0 g of the lignin derivative of 1 and 100 g of epichlorohydrin were introduced, and 2 g of an aqueous sodium hydroxide solution having a concentration of 20% by mass was refluxed under reduced pressure at a pressure of 100 mmHg (1.3 × 10 ⁴ Pa). It was added dropwise over 30 minutes. Thereafter, the reaction mixture was obtained by maintaining the reduced-pressure reflux state for 90 minutes.

  Next, the insoluble matter was removed from the reaction product by filtration, and the epichlorohydrin soluble portion was isolated. And epichlorohydrin was distilled off from this epichlorohydrin soluble part, and 21.8g of lignin secondary derivatives were obtained by drying.

<Manufacture of varnish for substrate impregnation>
Next, 20.0 g of the lignin secondary derivative obtained above, 10.0 g of the lignin derivative and 0.3 g of 2-methylimidazole were diluted with methanol to obtain 60 g of a lignin secondary derivative varnish having a resin content of 50% by mass.

<Manufacture of prepreg and resin plate>
Next, the varnish for impregnating the base material obtained above with a dip coater device with respect to kraft paper (basis weight 135 g / m ² ) so that the resin impregnation rate is 55 mass% (ratio to the whole prepreg). It was coated and then dried at 150 ° C. for 1 minute to obtain a prepreg. Eight prepregs thus produced were stacked and subjected to heat and pressure molding at 150 ° C. and 10 MPa for 30 minutes. As a result, a laminate having an average thickness of 1.6 mm was obtained.

(Sample No. 23-27)
Except for changing the type of lignin derivative and the type of reactive group to be introduced as shown in Table 3, sample No. In the same manner as in the case of No. 22, a lignin secondary derivative was obtained and a laminate was obtained. In addition, No. For No. 25, the laminated plate could not be formed due to insufficient melting during molding.

  Moreover, about the sample which used the vinyl group as a reactive group, it replaced with epichlorohydrin and allyl bromide was used, and it replaced with 2-methylimidazole and used azobisisobutyronitrile.

2. 2. Evaluation of lignin derivative 2.1 Evaluation of gel time 10 g of hexamethylenetetramine was added to 90 g of the lignin derivative, and the gel time (gelation time) at 150 ° C. of this sample was measured according to the method specified in JIS K 6910. The results are shown in Tables 1 and 2. It was.

  As is clear from Tables 1 and 2, it was recognized that in each example, a lignin derivative (preferably about 30 to 190) having a gel time value not too low and not too high as compared with each comparative example was obtained. . Such a gel-time lignin resin composition has high moldability and excellent mechanical properties after curing.

2.2 Evaluation of substrate impregnation 1 ml of the resin varnish used in the above was dropped onto the kraft paper surface with a dropper. After air-drying at room temperature, it was confirmed whether it penetrated to the back of the kraft paper.

<Evaluation criteria for substrate impregnation>
○: Penetrating to the back of the kraft paper ×: Insufficient penetration of the back of the kraft paper

2.3 Evaluation of elongation at bending fracture The laminated plate was subjected to a bending test until it broke according to the method defined in JIS-C6481. And the ratio (elongation at the time of bending fracture | rupture) of the change of the dimension after a test with respect to the dimension before a test was evaluated according to the following evaluation criteria.

<Evaluation criteria for elongation at bending fracture>
○: Elongation at bending fracture is 1% or more ×: Elongation at bending fracture is less than 1% As described above, the evaluation results of 2.2 and 2.3 are shown in Tables 1 to 3.

  The laminates corresponding to the examples were found to have high substrate impregnation properties, that is, high uniformity of the resin varnish with respect to kraft paper, and excellent elongation at the time of bending fracture. This is considered to be because the number average molecular weight of the lignin derivative contained in the lignin resin composition is within a predetermined range, so that the reactivity and meltability or solubility of the lignin derivative are optimized. Although not shown in the table, the sample No. 7 and 12 were slightly inferior in characteristics among the examples. On the other hand, sample no. 1, 2, 4, 5, 9-11, 22, and 24 were slightly superior in characteristics among the examples.

  On the other hand, the laminated board corresponding to the comparative example included those having poor substrate impregnation properties and those having poor (brittle) elongation at the time of bending fracture.

Claims (8)

And lignin induction body obtained by decomposition of biomass, and a cross-linking agent, only including,
The number average molecular weight of the lignin derivative is less than 1000,
When the mass ratio of the lignin derivative having a molecular weight of less than 1000 in the total amount of the lignin derivative is A and the mass ratio of the lignin derivative having a molecular weight of 1000 or more is B, the percentage of B / (A + B) is less than 20% by mass. A lignin resin composition characterized by the above. In the total amount of the lignin derivative, when the mass ratio of the lignin derivative having a molecular weight of 1000 or more and less than 3000 is B1, and the mass ratio of the lignin derivative having a molecular weight of 3000 or more is B2, B1> B2 and B1 / (A + B1 + B2 lignin resin composition according to claim 1 percentage is less than 0.1 wt% to 10 wt% of). The lignin resin composition according to claim 1 or 2 , wherein the lignin derivative has a molecular structure in which at least one of an ortho-position and a para-position of an aromatic ring is unsubstituted with respect to a hydroxyl group. The crosslinking agent, hexamethylenetetramine, and compounds containing two or more epoxy groups, lignin resin composition according to any one of claims 1 to 3 which contains at least one of. The lignin derivative is lignin resin composition according to any one of claims 1 to 4 reactive groups in the lignin compound obtained by decomposing the biomass is a secondary derivative has been introduced. The lignin resin composition according to claim 5 , wherein the reactive group is an epoxy group. It claims 1 to prepreg characterized by being obtained by impregnating lignin resin composition according to the substrate in any one of 6. A composite structure obtained by curing the prepreg according to claim 7 .