JP2006063271A - Fiber-reinforced epoxy resin composite material and its molded product - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fiber-reinforced epoxy resin composite material having a high performance and additional value by using as a matrix resin an epoxy resin synthesized by using a product obtained by liquefying and dissolving a lignocellulose material such as wood in phenols as a raw material, and reinforcing the matrix resin with a fiber. <P>SOLUTION: The fiber-reinforced epoxy resin composite material using a natural product as a main raw material is obtained by converting the liquefied and dissolved product obtained by heating and reacting the lignocellulose material with the phenols into an epoxy resin, mixing the resin with the fiber, and molding the resultant mixture. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a composite material mainly composed of lignocellulosic material such as wood. More specifically, the present invention relates to a composite material reinforced with fibers using an epoxy resin synthesized by liquefying and dissolving a lignocellulosic substance such as wood as a raw material in a matrix resin. The obtained composite material can be effectively used for molded products such as furniture members, building materials, interior materials and exterior materials of automobiles and home appliances, and housing members.

  Lignocellulosic materials such as wood have low thermoplasticity as they are, and once powdered, it is almost impossible to form them into boards, sheets and the like. Therefore, lignocellulosic substances that are discharged and discarded in large quantities after factory production processes and product use are low in added value for dairy materials and fillers such as straw substitutes for livestock rearing, flooring, etc. It is limited to those in the field and is incinerated and discarded without being used at all.

On the other hand, against the background of the demand for carbon dioxide emission reduction, various application development attempts have been made in various industries under the idea that the lignocellulosic material such as wood that grows by the carbon dioxide circulation by photosynthesis should be used effectively. It has been broken.
For example, by introducing at least one substituent into part of the hydroxyl group of the lignocellulosic material, a chemically modified lignocellulosic material such as chemically modified wood (chemically modified wood) is liquefied and dissolved in an organic solvent. It has been proposed to use the obtained wood liquefaction solution as various resin raw materials (for example, Patent Document 1).
However, in this case, the compound used for the solvent cannot be said to have high polymer reactivity, and for the preparation of a molded product, or for the resinization, the solvent used for liquefaction dissolution is volatilized. The third substance had to be further dissolved and used.

  Therefore, phenols were found as a solvent for liquefying or dissolving chemically modified wood, and a technology for obtaining phenols-formaldehyde resins was developed. In addition, a technology for making a phenol-formaldehyde resin adhesive having excellent solution properties, a fiberizing technology, and a foaming technology have been developed and patent applications have been filed (for example, Patent Document 2). To Patent Document 5).

Furthermore, lignocellulosic materials such as untreated wood, which is not chemically modified at all, can be easily liquefied and dissolved by heating under high temperature and pressure of 200 to 260 ° C. in the presence of phenols or bisphenols. Was found (for example, Patent Document 6).
Further, by subjecting lignocellulosic materials such as wood to pretreatment with halogen such as chlorination, and then liquefying and dissolving at a high temperature of 200 to 260 ° C. in a processing solution containing a liquefied solubilizer such as a phenol compound, It has also been proposed that a lignocellulose material liquefied solution can be produced efficiently and inexpensively (for example, Patent Document 7).
In addition, a technique for preparing adhesives and foams from solutions obtained by liquefying and dissolving phenols, polyhydric alcohols, polyethylene glycol, etc. at high temperatures without chemically modifying these woods has also been found. (For example, Patent Document 8 to Patent Document 10).
Japanese Patent Publication No. 63-1992 Japanese Examined Patent Publication No. 63-67564 JP 60-206883 A Japanese Examined Patent Publication No. 2-6851 JP-A 61-171744 JP-A-61-261358 JP-A-63-17961 JP-A-1-45440 Japanese Patent Laid-Open No. 1-158021 Japanese Patent Laid-Open No. 1-158022

In these conventional technologies, after liquefying and dissolving wood, the reactivity is utilized to synthesize phenolic resins and use them as adhesives, or to use materials with relatively low rigidity and low strength such as urethane resin foams. It has been proposed to use it as a heartwood or stuffing.
However, it cannot be said that the added value of these materials is sufficiently high, and it cannot be said that sufficient economic value has been obtained for the cost of recovering waste lignocellulosic materials and preparing resins and foams. It is in the present situation.

  The problem to be solved by the present invention is to obtain a composite material having high performance and high added value mainly composed of lignocellulosic material such as wood. More specifically, an epoxy resin using a lignocellulosic material such as wood as a raw material is synthesized, and a high-performance composite material obtained by reinforcing the fiber using the epoxy resin as a matrix resin is obtained.

  As a result of intensive studies in order to obtain a high-performance composite material while using natural products mainly of lignocellulosic materials as a main raw material, the present inventor has completed the present invention. That is, the present invention relates to a composite material in which an epoxy resin synthesized from a liquefied lysate produced by a reaction between a lignocellulosic substance and phenols is reinforced with fibers. An epoxy resin using a lignocellulosic material as a raw material is particularly excellent in affinity and adhesiveness with natural fibers, has good affinity between the resin and fibers in the composite material, and provides a high-performance composite material.

  According to the present invention, it is possible to obtain a composite material reinforced with fibers using an epoxy resin synthesized from a lignocellulosic material such as wood as a matrix resin. The composite material not only has high performance such as light weight, high strength, and high rigidity, but also has a high added value with a high biomass content and excellent environmental compatibility.

  The lignocellulosic material used as a starting material in the present invention includes wood flour, wood fiber, wood chips such as wood chips and veneer scraps, plant fiber such as straw, rice straw, coconut shell, GP (ground pulp), Various materials such as TMP (thermomechanical pulp), paper such as waste paper, and pulps are included, and any of those conventionally used in this field is used. Various kinds of wood at this time are widely included, and representative examples include makamba, sitka spruce, cedar, red pine, poplar, lawan and the like. The particle size of the pulverized product may be such that it can be sufficiently liquefied and dissolved. The liquefaction dissolution referred to in the present invention means that a lignocellulosic material such as wood reacts with phenols, and at least 80 wt% thereof is liquefied from the solid phase to the liquid phase.

  The phenols used in the present invention include divalent phenols such as phenol as monovalent phenol, o-cresol, m-cresol, p-cresol, 3,5-xylenol, 2,3-xylenol, α-naphthol and the like. Catechol, resorcinol, and the like, and phloroglucin as a trivalent phenol. Examples of bisphenols include bisphenol A, bisphenol F, bisphenol S, bisphenol AF, and halogenated bisphenol A. Considering including bisphenols, it is possible to use an epoxy resin made from a material that is obtained by liquefying and dissolving a phenolic compound having two or more phenolic hydroxyl groups per molecule with a lignocellulosic material. It is preferable for increasing the mechanical strength. However, if phenols having an excessively phenolic hydroxyl group in one molecule is used, the composite material becomes brittle. Therefore, it is preferable to use phenols having at most four phenolic hydroxyl groups in one molecule as phenols. . In liquefying and dissolving, the above phenols can be used alone or in various mixtures with each other.

  Usually, lignocellulosic material such as wood is added at a ratio of 10 to 1000 parts by weight per 100 parts by weight of phenols. In particular, it is preferable to add the lignocellulosic substance in the range of 50 to 300 parts by weight for the purposes of achieving uniform liquefaction / resinization and obtaining an epoxy resin having a high biomass content.

In the present invention, lignocellulosic material is liquefied by heating in a state of coexisting with phenols. In that case, it is preferable to use a pressure-resistant pressure vessel because it promotes uniform liquefaction and improves the uniformity of epoxy resinization and the heat resistance of the composite material. Moreover, in order to promote uniform liquefaction without a catalyst, the heating temperature is particularly preferably 170 ° C. or higher.
However, since the functional group inherent to lignocellulose may decrease if it is heated too much, it is more preferably heated to a range of 180 to 270 ° C, more preferably a range of 230 to 270 ° C. That is.

  Furthermore, in the presence of an acid catalyst, the lignocellulosic material can be liquefied and dissolved even in a relatively low temperature range of about 130 to 170 ° C. The acid catalyst may be an inorganic acid, an organic acid, or a Lewis acid, and examples thereof include sulfuric acid, hydrochloric acid, toluenesulfonic acid, phenolsulfonic acid, aluminum chloride, zinc chloride, and boron trifluoride. The usage-amount of an acid catalyst is 1-20 weight part normally with respect to 100 weight part of phenols, Preferably it is 2-4 weight part.

  In addition, when there is a purpose such as lowering the solution viscosity or promoting dissolution, water or alcohol, organic solvents such as acetone, ethyl acetate, etc. may be used from the beginning or during the dissolution. Addition and coexistence may be used. In particular, in order to liquefy and dissolve the lignocellulose substance at a temperature of 170 ° C. or higher without a catalyst, it is preferable to add a small amount of water for the purpose of promoting uniform liquefaction. A preferable amount of water added is 20 parts by weight or less, particularly preferably 15 parts by weight or less, based on 100 parts by weight of the lignocellulosic material.

  In liquefaction, it is preferable to dissolve the material while sufficiently stirring. By this stirring, torque can be added to the suspension to increase the efficiency of liquefaction and dissolution. Liquefaction can usually be achieved within 15 minutes to several hours. In particular, when lignocellulosic material is liquefied and dissolved at a temperature of 170 ° C. or higher in the absence of a catalyst, liquefaction is completed within 3 hours while maintaining a state in which many hydroxyl groups necessary for epoxy resin formation remain. It is preferable because liquefaction can be completed and polyfunctional epoxy resin can be easily synthesized by subsequent epoxy resin conversion, and a composite material excellent in heat resistance, solvent resistance and strength characteristics can be easily obtained. The concentration of the lignocellulose material in the liquified lysate of the lignocellulosic material thus obtained varies depending on the purpose of use of the solution, but ranges up to about 90% by weight. Even if any kind of coniferous tree or broad-leaved tree is used as a raw material, a liquid material having substantially the same properties can be obtained by selecting treatment conditions. Since the obtained liquid has many functional groups, it has high reactivity and becomes a raw material for epoxy resin synthesis.

  For the epoxy resinization, a method obtained by adding epichlorohydrin to the liquefied product and reacting the hydroxyl group in the liquefied product with epichlorohydrin in the presence of an alkali can be preferably used. At that time, it is preferable to add the epichlorohydrin in a large excess with respect to the number of moles of phenols, and to recover the excess after the resin synthesis, and to react the epichlorohydrin under alkaline conditions. It is preferable to add an aqueous sodium hydroxide solution at least twice as much as the amount of hydroxyl groups in the phenol. The epoxidation reaction temperature is preferably kept at 100 ° C. or lower.

  As an epoxy resin curing agent used in the present invention, various commercially available epoxy resin curing agents can be used. For example, curing using an acid anhydride curing agent, an amine curing agent, a phenol curing agent, a thiol curing agent, or the like is preferable from the viewpoint of adjusting curability and cured product characteristics. In particular, when an acid anhydride curing agent is used, it is generally preferable from the viewpoint of improving heat resistance and chemical resistance, and when an amine curing agent is used, it is generally preferable from the viewpoint of low temperature curing and high adhesiveness.

  Specific examples of the acid anhydride curing agent include, for example, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylhymic anhydride, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, trialkyltetrahydrophthalic anhydride, Methylcyclohexene dicarboxylic acid anhydride, phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, benzophenone tetracarboxylic anhydride, ethylene glycol bistrimellitate, glycerol tris trimellitate, dodecenyl succinic anhydride, polyazeline acid anhydride And poly (ethyl octadecanedioic acid) anhydride. Of these, dodecenyl succinic anhydride, trialkyltetrahydrophthalic anhydride, and ethylene glycol bistrimellitate are more preferable from the viewpoint of chemical resistance.

  Specific examples of the amine curing agent include, for example, 2,5 (2,6) -bis (aminomethyl) bicyclo [2,2,1] heptane, isophoronediamine, ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylene. Pentamine, diethylaminopropylamine, bis (4-amino-3-methyldicyclohexyl) methane, diaminodicyclohexylmethane, bis (aminomethyl) cyclohexane, metaphenylenediamine, diaminodiphenylmethane, diaminodiphenylsulfone, diaminodiethyldiphenylmethane, diethyltoluenediamine, And dicyandiamide. Among these, triethylene glycol diamine oligomer, triethylenetetramine, diaminodiphenyl sulfone, diaminodiphenylmethane, and dicyandiamide are preferable from the viewpoint of high adhesiveness. For film adhesive applications, dicyandiamide and diaminodiphenyl sulfone having high potential are particularly preferable.

  Specific examples of the phenol-based curing agent include derivatives such as phenol novolac resins having various molecular weights, cresol novolac resins having various molecular weights, bisphenol A, bisphenol F, bisphenol AD, and nuclear allylic compounds of these phenols. Of these, phenol novolac resins are more preferable from the viewpoint of curability.

  Examples of the thiol-based curing agent include adducts of low-molecular dimercaptan and polyepoxide, reaction products of hydrogen sulfide and polyepoxide, and esterified products of mercaptopropionic acid or mercaptoglycolic acid and polyhydric alcohol. Examples include Capcure 3-800 (trademark), Capture WR-6 (trademark), EpomateQX11 (trademark), EpomateQX40 (trademark) manufactured by Japan Epoxy Resin Co., Ltd., and Adeka Hardener EH316 (trademark) manufactured by Asahi Denka Kogyo Co., Ltd. , ADEKA HARDNER EH317 (trademark), LP-2, LP-3, LP-12, LP-23, LP-31, LP-32, LP-55, LP-56, Toyo Chemical Co., Ltd. THEIC-BMPA (trademark) manufactured by Co., Ltd.Among these, THEIC-BMPA (2,4,6-trioxo-1,3,5-triazine-1,3,5-triyltriethyl-tris (3-mercaptopropionate)) is compared with mercaptan odor. It is preferable because it is weak and has good curability.

  The amount of the epoxy resin curing agent used is preferably 4 to 100 parts by weight, more preferably 20 to 100 parts by weight, based on 100 parts by weight of the epoxy resin, from the viewpoint of heat resistance and curability. In relation to the epoxy group equivalent in the epoxy resin, it is preferable that the functional group of the curing agent is a stoichiometric equivalent from the viewpoint of improving the heat resistance. It is preferable from the viewpoint of enhancing the elastic modulus and energy absorption function. As the equivalent ratio, per 1 equivalent of epoxy group, in the case of an acid anhydride type curing agent, the acid anhydride group is 0.5 to 1.2 equivalents, more preferably about 0.8 to 1.0 equivalents, amine type In the case of a curing agent, the active hydrogen is 0.3 to 1.4 equivalent, more preferably about 0.4 to 1.1 equivalent. In the case of a phenolic curing agent, the active hydrogen is 0.5 to 1.2. Equivalent, more preferably about 0.7 to 1.0 equivalent, and in the case of a thiol-based curing agent, the active hydrogen should be about 0.3 to 1.3 equivalent, more preferably about 0.5 to 1.1 equivalent. A good balance between mechanical properties and heat resistance / curability is preferable.

  Fibers are used as reinforcing materials in the composite material of the present invention. As the fibers, various reinforcing fibers that have been used in fiber-reinforced composite materials such as inorganic fibers such as glass fibers and carbon fibers, and organic fibers such as aramid fibers and nylon fibers can be used. Reinforcing fibers that are particularly suitable for the invention are fibers made of natural products.

Fibers made of natural products can be broadly divided into plant fibers, animal fibers and mineral fibers.
Plant fibers suitable for the present invention include pulps such as GP (ground pulp) and TMP (thermomechanical pulp), wood fibers, bamboo fibers, hemp fibers, flax (flux) fibers, jute fibers, sisal fibers, manila fibers, Examples thereof include ramie hemp fiber, palm fiber, coir fiber, bagasse, straw, kenaf fiber, hemp fiber, cotton fiber (including cellulose fiber such as cellulose microfibrillated pulp), paper such as used paper. Among these, bamboo fiber, flax (flux) fiber, jute fiber, sisal hemp fiber, manila hemp fiber, ramie hemp fiber and cellulose fiber are particularly preferred because of their excellent strength and elastic modulus.

Animal fibers suitable for the present invention include silk fibers, wool, leather fibers and the like.
Examples of mineral fibers suitable for the present invention include rock fibers and basalt (basalt) fibers.
These fibers may be used by mixing types. Among these, the use of plant fibers as reinforcing fibers is most preferable in terms of achieving both the light weight, high strength, and high rigidity of the composite material and the environmental compatibility of the material.

  The content of reinforcing fibers in the composite material is preferably in the range of 5 to 80 wt%. If the amount is too small, the mechanical properties of the composite material will be poor, and if there are too many reinforcing fibers, sufficient resin will not be present between the fibers, and the properties of the reinforcing fibers may not be reflected in the composite material. In that sense, the content of reinforcing fibers in the composite material is more preferably 20 to 70 wt%, and still more preferably 40 to 70 wt%.

The orientation of the reinforcing fiber may be any one of unidirectional, multidirectional, two-dimensional, three-dimensional, and random, as in the conventional fiber-reinforced composite material, and the reinforcing fiber form is aligned in one direction, woven fabric, non-woven fabric Alternatively, mat or short fiber dispersion may be used.
The resin composition containing the epoxy resin and the curing agent used for the composite material of the present invention is blended with additives such as a curing accelerator, a filler, a coupling agent, an antioxidant, and an ultraviolet absorber as necessary. . The filler is used for controlling the resin rheological characteristics for molding the composite material, and for improving the mechanical strength / elastic modulus, impact absorption performance, heat resistance, flame retardancy, and the like.

There is no restriction | limiting in particular in the said filler, If it is conventionally used, it can be used. Specific examples include clay minerals, mica scale pieces, glass pieces, calcium carbonate, barite, precipitated barium sulfate, aluminum hydroxide and the like.
When the filler is used, the amount used is preferably 5 to 50 wt%, more preferably 5 to 30 wt% with respect to the resin composition. When the amount of the filler used is less than 5 wt%, there is a tendency that sufficient energy absorption performance cannot be improved even if the filler is used. When the amount exceeds 50 wt%, it is difficult to impregnate the reinforcing fiber. The mechanical strength tends to decrease.
In the process of obtaining the molded product of the fiber-reinforced epoxy resin composite material described above, various conventionally known molding methods can be used. For example, hand layup molding, prepreg molding, vacuum pressure molding, press molding, autoclave molding, resin injection molding (RTM, RIM), film impregnation molding (RFI), pultrusion molding, filament winding molding, injection molding, etc. Can do. In molding the composite material, it is preferable to heat while applying pressure from the viewpoint of promoting the curing of the resin and removing voids.

Hereinafter, the present invention will be described in more detail with reference to examples.
(Liquefaction of wood)
Weigh 5 g of dried sitka spruce wood flour (20-80 mesh) and 5 g of resorcinol in a suitable container such as a beaker, mix them well, pack them into a 50 ml stainless steel pressure vessel, seal the bottle, It was allowed to stand in an oil bath for 2.5 hours. After the completion, the mixture was cooled to room temperature, opened, and the contents were taken out. As a result, a dark brown viscous solution was obtained. This is called resorcinol liquefied wood. Part of the solution was diluted with 150 ml of 1,4-dioxane, and then the diluted reaction solution was filtered using a glass fiber paper (TOYO “GA100” (trademark)) to obtain a liquefied product and an insoluble residue. And separated. The insoluble residue was further washed several times with 1,4-dioxane, pre-dried, dried at 105 ° C. for 4 hours, and weighed to determine the percentage of insoluble residue. The resulting insoluble residue rate was 4.1%.

(Resorcinol liquefied wood epoxy resin)
Next, an epoxy resin was synthesized from resorcinol liquefied wood prepared by the same procedure as described above. First, 25 g of resorcinol liquefied wood and 105 g of a large excess of epichlorohydrin (10 times mol of resorcinol present in the liquefied wood) are weighed into a 300 ml four-necked flask, and a stirring motor, thermometer, dropping funnel A reflux condenser was attached. The flask was placed in an oil bath at about 110 ° C., and the temperature was controlled so that the temperature inside the flask became 100 ° C. while stirring the contents. Here, 36.3 g of a 50% aqueous sodium hydroxide solution corresponding to 2 times mol of the hydroxyl group content of resorcinol in the contents was dropped over 2 hours. After completion of the dropwise addition, stirring was continued for another 0.5 hours to complete the reaction. Unreacted epichlorohydrin and water were distilled off and collected from the reaction product under reduced pressure at 80 ° C. using an evaporator to obtain a crude resin product. This crude product was dissolved in acetone, the solution was suction filtered using glass fiber paper (TOYO “GA100”), and acetone was distilled off from the collected filtrate at 80 ° C. under reduced pressure using an evaporator. Thus, resorcinol liquefied wood epoxy resin was obtained. The epoxy equivalent was measured and found to be 256 g / eq.

(Molding of composite material reinforced with resorcinol liquefied wood epoxy resin with flax fiber)
To 10 g of the synthesized resorcinol liquefied wood epoxy resin, 2.1 g of diaminodiphenylmethane (DDM) having active hydrogen equivalent to the epoxy equivalent and stoichiometry was added and mixed well to obtain a resin / curing agent composition. This was coated on release paper on a hot plate heated to 50 ° C. to obtain a resin film (weight per unit area: 200 g / m ² ). The resin film was pressure-bonded to the top and bottom of a separately prepared flax fiber nonwoven fabric (weighing 300 g / m ² ), and the nonwoven fabric was impregnated with a hot press machine at 50 ° C. to prepare a prepreg.

After superimposing the three prepared prepregs, they were placed on a release-treated aluminum plate, wrapped in a nylon bag film, and the inside was evacuated. The entire plate was placed in a hot press machine, molded by heating at 130 ° C. under a pressure of 6 MPa for 3 hours, and then heated at 150 ° C. for 2 hours to obtain a flax fiber reinforced wood epoxy resin composite material.
The biomass content in this composite can be calculated to be about 63 wt%.

(Measurement of bending properties of composite materials)
The bending strength and elastic modulus of the composite material plate were measured in a three-point bending mode at 25 ° C. in accordance with JIS K-6911. The crosshead speed was 5 mm / min. The bending strength was 98 MPa, and the flexural modulus was sufficiently high at 8.2 GPa. When the fracture surface after the strength measurement was observed with a scanning electron microscope, the adhesion between the reinforcing fiber and the resin was good.

(Liquefaction of wood)
Weigh 5 g of dried makanba wood flour (20-80 mesh) and 5 g of bisphenol A in a suitable container such as a beaker, mix them well, pack them into a 50 ml stainless steel pressure vessel, seal them, In an oil bath for 2.5 hours. After the completion, the mixture was cooled to room temperature, opened, and the contents were taken out. As a result, a black high-viscosity material was obtained. This is called bisphenol A liquefied wood. Part of the solution is diluted by adding 150 ml of 1,4-dioxane, and then the diluted reaction solution is filtered using glass fiber paper (TOYO “GA100”) to separate the liquefied product from the insoluble residue. did. The insoluble residue was further washed several times with 1,4-dioxane, pre-dried, dried at 105 ° C. for 4 hours, and weighed to determine the percentage of insoluble residue. The resulting insoluble residue rate was 5.2%.

(Bisphenol A liquefied wood epoxy resin)
Next, an epoxy resin was synthesized from bisphenol A liquefied wood prepared by the same procedure as described above. First, 25 g of bisphenol A liquefied wood and 51 g of a large excess of epichlorohydrin (10 times mol of bisphenol A present in the liquefied wood) are weighed into a 300 ml four-necked flask, and a stirring motor, thermometer, A dropping funnel and a reflux condenser were attached. The flask was placed in an oil bath at about 110 ° C., and the temperature was controlled so that the temperature inside the flask became 100 ° C. while stirring the contents. Here, 17.5 g of a 50% sodium hydroxide aqueous solution corresponding to 2 times mol of the hydroxyl group content of bisphenol A in the contents was dropped over 2 hours. After completion of the dropwise addition, stirring was continued for another 0.5 hours to complete the reaction. From the reaction product, unreacted epichlorohydrin and water were distilled off at 80 ° C. using an evaporator to obtain a crude resin product. This crude product was dissolved in acetone, the solution was suction filtered using glass fiber paper (TOYO “GA100”), and acetone was distilled off from the collected filtrate at 80 ° C. under reduced pressure using an evaporator. Thus, bisphenol A liquefied wood epoxy resin was obtained. The epoxy equivalent was measured and found to be 244 g / eq.

(Molding of composite material reinforced with bisphenol A liquefied wood epoxy resin with flax fiber)
To 10 g of the synthesized bisphenol A liquefied wood epoxy resin, 2.2 g of diaminodiphenylmethane having an active hydrogen equivalent to the epoxy equivalent and stoichiometry was added and mixed well to obtain a resin / curing agent composition. This was coated on release paper on a hot plate heated to 100 ° C. to obtain a resin film (weight per unit area: 200 g / m ² ). The resin film was pressure-bonded to the top and bottom of a separately prepared flax fiber nonwoven fabric (weighing 300 g / m ² ), and the nonwoven fabric was impregnated with a hot press machine at 100 ° C. to prepare a prepreg.

After superimposing the three prepared prepregs, they were placed on a release-treated aluminum plate, wrapped in a nylon bag film, and the inside was evacuated. The entire plate was placed in a hot press machine, molded by heating at 130 ° C. under a pressure of 6 MPa for 3 hours, and then heated at 150 ° C. for 2 hours to obtain a flax fiber reinforced wood epoxy resin composite material.
The biomass content in the composite can be calculated to be about 62 wt%.

(Measurement of bending properties of composite materials)
The bending strength and elastic modulus of the composite material plate were measured in a three-point bending mode at 25 ° C. in accordance with JIS K-6911. The crosshead speed was 5 mm / min. The bending strength was 96 MPa, and the flexural modulus was sufficiently high as 7.5 GPa. When the fracture surface after the strength measurement was observed with a scanning electron microscope, the adhesion between the reinforcing fiber and the resin was good.

As Comparative Example 1, a curing agent (DDM) was added to resorcinol liquefied wood epoxy resin obtained in Example 1 in the same manner as in Example 1; however, no reinforcing fiber was added and the resin was cured under the same curing conditions as in Example 1. A plate was formed.
The bending strength of the resin plate in Comparative Example 1 was 64 MPa, and the flexural modulus was 3.3 GPa, which was lower than Example 1.

As Comparative Example 2, a curing agent (DDM) was added to the bisphenol A liquefied wood epoxy resin obtained in Example 2 in the same manner as in Example 2, but no reinforcing fiber was added, and the resin was cured under the same curing conditions as in Example 2. A cured plate was formed.
The bending strength of the resin plate in Comparative Example 2 was 70 MPa, and the flexural modulus was 3.4 GPa, which was lower than Example 2.

As Comparative Example 3, a commercially available bisphenol A type epoxy resin (Ep1001 manufactured by Japan Epoxy Resin Co., Ltd.) was used to add a curing agent (DDM) in the same manner as in Example 2, and the flax fiber was reinforced to produce a composite material. A plate was formed. The biomass content in this composite can be calculated to be about 50 wt%.
The composite material plate in Comparative Example 3 had a bending strength of 83 MPa and a flexural modulus of 7.2 GPa. That is, the mechanical properties were inferior to those of Example 2 having a relatively high biomass content as a composite material. When the fracture surface after the strength measurement was observed with a scanning electron microscope, it was found that the adhesion between the reinforcing fiber and the resin was poor as compared with Example 2.

The resorcinol liquefied wood epoxy resin obtained in Example 1 was added with a curing agent (DDM) in the same manner as in Example 1, and bamboo fiber non-woven fabric was used instead of flax fiber. A composite plate was formed. However, the basis weight of the bamboo fiber nonwoven fabric is 160 g / m ² , and the biomass content in this composite material can be calculated as about 58 wt%. The composite material plate had a flexural strength of 76 MPa and a flexural modulus of 6.7 GPa.

Claims (8)

  A fiber-reinforced epoxy resin composite material, which is reinforced with fibers of an epoxy resin synthesized from a liquefied lysate produced by the reaction of lignocellulosic substances and phenols.   The fiber-reinforced epoxy resin composite material according to claim 1, wherein the phenol is a molecule having two or more phenolic hydroxyl groups.   2. The epoxy resin obtained by reacting the liquefied dissolved material with epichlorohydrin as the raw material is an epoxy resin obtained by reacting the lignocellulosic material with the phenols according to claim 1. The fiber-reinforced epoxy resin composite material described.   The fiber-reinforced epoxy resin composite material according to claim 1, wherein the fiber is a fiber made of a natural product.   The fiber-reinforced epoxy resin composite material according to claim 4, wherein the fiber made of natural products is a vegetable fiber.   The fiber-reinforced epoxy resin composite material according to claim 4, wherein the fiber made of a natural product is an animal fiber.   The fiber-reinforced epoxy resin composite material according to claim 4, wherein the fiber made of a natural product is a mineral fiber.   A molded product comprising the fiber-reinforced epoxy resin composite material according to claim 1.