JP2020203968A - Thermosetting resin composite powder containing lignin - Google Patents

Abstract

To improve thermosetting workability of a composition containing lignin and an epoxy compound, and improve a lignin content of a cured body.SOLUTION: Thermosetting resin composition powder contains modified lignin chemically modified with polyethylene glycol and an epoxy compound. Thermosetting resin composition powder composed of modified lignin and an epoxy compound is produced by uniformly mixing an aggregate obtained by subjecting modified lignin chemically modified with polyethylene glycol to alcohol treatment with an epoxy compound, drying a solid matter containing the modified lignin, the epoxy compound and residual alcohol, and then crushing the solid matter. There is also provided a method for producing a thermosetting plastic molding using the thermosetting resin composition powder.SELECTED DRAWING: None

Description

The present invention relates to a thermosetting resin composition powder containing lignin, a method for producing the same, and a method for producing a thermosetting plastic molded product.

Plastic materials are mainly synthesized from petroleum, but in order to meet the needs for reducing carbon dioxide emissions in recent years, synthesis from various biomass sources is also being attempted. Lignin is a component that accounts for 20 to 30% of wood, and although it is obtained in large quantities from thinned wood and papermaking processes, it has not been widely used as a basic polymer raw material for industrial products. This is mainly because lignin is a macromolecule with a complicated structure and has individual differences depending on the tree species, so that it is expensive as a raw material for large-scale chemical products due to the difficulty of separation and purification. In recent years, an acid hydrolysis treatment of a wood raw material using polyethylene glycol as a solvent, which is different from the conventional method, makes it easier to extract a lignin component that is relatively more homogeneous than the conventional method as a modified lignin, and continues as a powder organic compound raw material. Examples have been found that can be supplied.

In Patent Document 1, the safety of ethylene glycol-based compounds having the same polyethylene glycol or similar structure is utilized again by utilizing the fact that the modified lignin is easily separated and purified by using polyethylene glycol having a small environmental load. We have found an example of making a thermosetting plastic by liquefying it and curing it together with an industrially general-purpose epoxy compound, paying attention to the fact that it is easily dissolved in a highly organic solvent.

However, in this method, it was necessary to heat at 80 ° C. or higher and stir for 4 hours or longer in order to sufficiently dissolve the modified lignin in the polyethylene glycol-based organic solvent. Further, when molding is performed by a hand lay-up method, a vacuum impregnation method, or the like using a mixture with an epoxy compound, it is necessary to maintain the temperature at 80 ° C. or higher in order to maintain the fluidity of the mixture. If the temperature is raised too high in order to obtain sufficient fluidity, there is a difficulty in the process that curing proceeds in the middle of the molding process. In addition, since the boiling point of polyethylene glycol is higher than the curing temperature with the epoxy compound, it is difficult to remove the polyethylene glycol by the evaporation operation, and unreacted polyethylene glycol remains in the cured product, which leads to a long curing time. There was a problem that it took more than 60 hours without a catalyst and the strength of the plastic was lowered. Furthermore, since the polyethylene glycol solvent cannot be removed, as a result, the curing process in which the solvent is contained is unavoidable, and the content of lignin in the plastic is relatively lowered, which hinders the spread of lignin as an industrial raw material. There was a big problem.

However, general-purpose organic solvents such as dimethylformamide (DMF) and N-methylpyrrolidone (NMP), which are good solvents for lignin, are solvents that easily dissolve modified lignin at room temperature but have a high boiling point. In order to completely remove the epoxy compound, a drying temperature of 150 ° C. or higher, which is higher than the curing temperature of the epoxy compound, is required, and there are difficulties in molding such as distortion of the resin due to simultaneous progress of solvent removal and curing. In addition, there are problems with environmental load and safety regarding DMF and the like.

Furthermore, in order to uniformly mix the modified lignin and the epoxy compound, it is necessary to dissolve the modified lignin in a solvent at a high temperature to make a low-viscosity liquid, and then mix the modified lignin with the epoxy compound for a long time. During that time, the curing reaction proceeds, and it is necessary to immediately proceed with the process up to the curing process for the resin in the state of the mixed solution, and it is difficult to stock it as a precursor and perform the curing process later. There was a drawback that the process was inflexible.

As described above, in the prior art for obtaining a thermosetting plastic from modified lignin, the process is complicated by the high dissolution temperature and high solvent removal temperature of lignin, the solvent remains in the final plastic, and the chemical substances used. There was a problem in terms of environmental load.

JP-A-2018-104688

The present invention is obtained by mixing modified lignin and epoxy compound at a curing temperature or lower, can be stored as a pre-curing raw material resin containing modified lignin and epoxy compound, and can be used for curing treatment at a processing site. An object of the present invention is to provide a sex resin composition powder and a method for producing the same.

The present invention provides at least the following aspects in order to solve the above problems.
(Aspect 1)
A thermosetting resin composition powder containing a modified lignin chemically modified with polyethylene glycol and an epoxy compound.

(Aspect 2)
The thermosetting resin composition powder according to aspect 1, which is an in-situ polymerization type thermosetting resin composition powder.

(Aspect 3)
The thermosetting resin composition powder according to aspect 1 or 2, further containing alcohol and having an alcohol content of 5% by weight or less.

(Aspect 4)
The thermosetting resin composition powder according to aspect 1 or 2, which does not contain alcohol.

(Aspect 5)
Modified lignin chemically modified with polyethylene glycol is treated with alcohol to prepare an alcohol-containing modified lignin solid, and the alcohol-containing modified lignin solid is heated and mixed with an epoxy compound to obtain the modified lignin and the epoxy compound. A mixture containing alcohol is prepared, and the obtained mixture is dried to remove or reduce alcohol, and then pulverized to obtain a thermosetting resin composition powder containing a modified lignin and an epoxy compound. A method for producing a thermosetting resin composition powder.

(Aspect 6)
The method for producing a thermosetting resin composition powder according to aspect 5, wherein the drying treatment is performed under reduced pressure and temperature rise.

(Aspect 7)
The method for producing a thermosetting resin composition powder according to aspect 5 or 6, wherein the residual alcohol of the mixture is reduced to 5% by weight or less by a drying treatment.

(Aspect 8)
The method for producing a thermosetting resin composition powder according to aspect 5 or 6, which does not leave residual alcohol in the mixture in the drying treatment.

(Aspect 9)
The thermosetting resin composition powder according to any one of aspects 1 to 4 or the thermosetting resin composition powder produced by the production method according to any one of aspects 5 to 8 is heated. A method for producing a thermosetting plastic molded product, which comprises melting, molding with a mold, and heat-curing to obtain a thermosetting plastic molded product.

(Aspect 10)
The thermosetting resin composition powder according to any one of aspects 1 to 4 or the thermosetting resin composition powder produced by the production method according to any one of aspects 5 to 8 is used as it is. A method for producing a thermosetting plastic molded product, which comprises heat-press molding and heat-curing to obtain a thermosetting plastic molded product.

(Aspect 11)
The thermosetting resin composition powder according to any one of aspects 1 to 4 or the thermosetting resin composition powder produced by the production method according to any one of aspects 5 to 8 is used as a fiber. A method for producing a thermosetting plastic molded product, which comprises molding and heat-curing the product by mixing with or in combination with a fiber structure.

(Aspect 12)
The thermosetting plastic molding according to aspect 11, wherein the thermosetting resin composition powder is heated and melted at a curing temperature or lower, impregnated into a fiber fabric, cooled to prepare a prepreg, and then heat-press-cured in an arbitrary shape. How to make a body.

(Aspect 13)
The thermosetting resin composition powder according to any one of aspects 1 to 4 or the thermosetting resin composition powder produced by the production method according to any one of aspects 5 to 8 is inorganic. A method for producing a thermosetting plastic molded product, which comprises mixing with powder, molding, and heat-curing.

According to the present invention, it can be stored as a pre-curing raw material resin containing modified lignin and an epoxy compound, can be used for curing treatment at a processing site, and is excellent in usability because it is a powder. Lignin-containing thermosetting property A resin composition powder is provided. Further, by producing a thermosetting plastic molded product using the thermosetting resin composition powder, a lignin-containing plastic molded product having excellent productivity and excellent properties can be obtained.

In the following, for the sake of the description of the present invention, the preferred additional effects that can be obtained by the present invention are described in some detail, but it should be noted that the present invention is not limited to those that can obtain the following effects.

According to the present invention, by treating the modified lignin to be used in an alcohol solvent at a relatively low temperature of about 100 to 80 ° C. or less, the modified lignin is easily liquefied, and it is an industrially general-purpose epoxy compound. It is possible to create a state in which it is easy to mix, and the efficiency of producing a thermosetting plastic resin liquid is greatly improved. In addition, by treating with alcohol instead of the conventional high boiling point organic solvent, the removal temperature of the solvent from the mixture containing the modified lignin and the epoxy compound is lowered, and the removal temperature of the solvent and the thermosetting temperature of the resin are adjusted. Since a large difference can be provided between the two, it is possible to move to the thermosetting process after sufficient solvent removal, and by making it possible to provide lignin as a raw material powder before curing, at the molding site. Make workability easy and diverse. Furthermore, by utilizing the phenomenon that the modified lignin liquefies and aggregates in alcohol, the modified lignin that is easily mixed with the epoxy compound can be precipitated and separated as a solid substance, and the epoxy compound can be separated. Excess solvent can be easily recovered, removed, and reused in advance before mixing with.

According to the present invention, a high boiling point organic solvent is not required as compared with the prior art, and the mixing of the modified lignin with the alcohol and the epoxy compound is completed at a low temperature and in a short time, so that the time is significantly reduced from the conventional method. Can be planned. In addition, since a low boiling point organic solvent can be removed at a low temperature, it is advantageous in process saving and environmental safety.

Further, according to the present invention, after mixing with alcohol by the above method, a modified lignin solid containing the same solvent is obtained, and then mixed with an epoxy compound at a temperature lower than the curing temperature of epoxy, for example, 100 ° C. or lower, and unreacted. Can be prepared and stored as a powder of a mixture. Compared with the prior art, it is not necessary to mix the modified lignin, the solvent and the epoxy compound at a high temperature, for example, above 100 ° C., and the uncured mixture can be stored at room temperature. Compared to the conventional method, which must be used up immediately after mixing the liquid, it has an advantage in process saving, and its powder form is extremely suitable for supply to the site as an industrial raw material.

Since it is easy to separate and remove alcohol while maintaining a good mixture of modified lignin and epoxy compound, no solvent remains in the product after curing, and the ratio of modified lignin and epoxy compound can be easily adjusted. As a result, it is possible to produce a high lignin-containing epoxy resin in which the content of modified lignin, which was only about 40% in the conventional method, is increased to about 90% without reducing the hardness.

Since most of the solvent can be removed at a temperature lower than the curing temperature of the epoxy as compared with the prior art, it is possible to obtain a solid unreacted mixture before curing. Therefore, various artificial fibers impregnated with an unreacted mixture can be produced as a prepreg raw material for fiber reinforced plastics. In addition, this prepreg or a laminate of an unreacted mixture solid and an artificial fiber woven fabric can be processed by heat molding, and modified lignin is used as compared with the hand lay-up method and vacuum impregnation method in the prior art. Has process-saving properties for manufacturing fiber reinforced plastics. Further, since it is obtained as a powder, it can be easily mixed with a flame-retardant inorganic substance which is the same powder, which contributes to an easy manufacturing method of a flame-retardant plastic.

Since the thermosetting plastic molded product produced by the production method of the present invention was found to have thermoplasticity while being a thermosetting resin, the thermosetting plastic molded product can be modified and deformed after curing. effective.

FIG. 1 is a photograph showing how modified lignin is treated with ethanol. FIG. 2 is a photograph of modified lignin treated with various alcohols. FIG. 3 is an infrared absorption analysis chart of modified lignin before and after dissolution in alcohol. FIG. 4 is an infrared absorption analysis chart of a cured epoxy product obtained by curing the thermosetting resin composition of Examples. FIG. 5 is a photograph of the modified lignin solid material treated with ethanol until the curable resin composition powder is produced. FIG. 6 is a photograph showing a state in which a thermosetting resin composition powder is placed in a mold and heated and cured to produce a plastic plate obtained. FIG. 7 is a photograph showing plastics made from thermosetting resin composition powders having different mixing rates of modified lignin. FIG. 8 is a photograph showing the state of thermoplasticity of the thermosetting resin composition powder after the thermosetting treatment.

(Curable resin composition powder)
The present invention provides a thermosetting resin composition powder containing a modified lignin chemically modified with polyethylene glycol and an epoxy compound.

Conventionally, in order to obtain a solid composition containing lignin and an epoxy compound, it has been necessary to dissolve or melt it in an organic solvent such as dimethylformamide (DMF) or polyethylene glycol to liquefy it. The thermosetting resin composition powder contained was not present. The present inventors first used modified lignin chemically modified with polyethylene glycol and alcohol as an organic solvent to obtain a solid substance of a thermosetting resin composition containing modified lignin, an epoxy compound and alcohol. It has been successfully manufactured (Japanese Patent Application No. 2017-243121). However, the solid substance of this thermosetting resin composition contained about 33% by weight of alcohol, was a very soft elastic body, and was not powdered. This time, the present inventor can remove or reduce alcohol by highly drying the solid substance of the thermosetting resin composition by drying under reduced pressure or the like, and the resulting thermosetting resin can be obtained. The solid of the composition can be crushed into a thermosetting resin composition powder, and further, since this thermosetting resin composition powder does not contain an alcohol solvent or contains a small amount of alcohol solvent, lignin. The present invention has been completed by finding that the degree of freedom in the melting, molding and thermosetting steps for producing a thermosetting plastic molded product from an epoxy compound is improved, and that the lignin content of the cured product can be made higher than before.

(Modified lignin)
As the modified lignin used in the present invention, a polyethylene glycol chain bonded to the skeleton of lignin is used. As a method for binding the polyethylene glycol chain to lignin, a derivation method using polyethylene glycol having an epoxy group, a method of dissolving polyethylene glycol in a black liquid containing lignin and treating it, and an acid solvolysis using polyethylene glycol as a medium. Decomposition methods and the like are exemplified, but in the present invention, modified lignin obtained by the acid solvolysis method is preferably used. The molecular weight of polyethylene glycol used in the reaction here is 100 to 1000, preferably 200 to 600. The plant biomass used as a raw material for producing modified lignin is not particularly limited, but softwood materials such as sugi and cypress, broadleaf wood materials such as hippopotamus and cypress, and herbaceous biomass such as rice straw, bagasse and bamboo. Is used. Softwoods such as sugi and cypress, especially sugi, are preferred raw materials. For acid solvolysis, preferably, about 5 times by weight of polyethylene glycol and 0.1 to 0.9% sulfuric acid with respect to polyethylene glycol are added to the chips or pulverized products of these plant biomass, and the temperature is about 140 ° C. It is carried out by heating for 60 to 90 minutes. After diluting the reaction product with a dilute caustic soda solution of preferably 0.1 to 0.2 M, the insoluble pulp component is removed by filtration, and the filtrate is acidified with sulfuric acid or the like to form a precipitate. The substance obtained by removing the precipitate by filtration or centrifugation is used as modified lignin.

As the modified lignin modified with polyethylene glycol, modified lignin having a polar group added may also be used. A carboxyl group, an amino group, and a hydroxyl group are preferably used as the polar group, and a carboxyl group is more preferably used.

(Epoxy compound)
The epoxy compound used in the present invention may be any epoxy compound that can be thermally cured by reacting with the hydroxyl group contained in the modified lignin. Examples thereof include aliphatic systems such as epoxidized soybean oil and alkylene-1,6-diepoxy; bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, and the like. These epoxy compounds can be used alone or in admixture of two or more.

The blending ratio of the modified lignin and the epoxy compound in the thermosetting resin composition powder of the present invention may be in the range of 1:99 to 99: 1 in terms of weight ratio, as long as it can be thermally cured to produce a thermosetting plastic. However, in order to have a practical hardness after thermosetting, it is preferably in the range of 40:60 to 94: 6, and further 60:40 to 90:10.

(Curing accelerator)
The thermosetting resin composition powder of the present invention may optionally contain a curing accelerator together with the epoxy compound. The curing accelerator to be used may be one that promotes the curing reaction between the epoxy compound and the modified lignin, and a curing accelerator that promotes the curing reaction between the epoxy compound and the hydroxyl group of the epoxy resin is known. For example, tertiary amines and tertiary amines such as 1,5-diazabicyclo (4,3,0) -nonen-5 (commonly known as DBN) and 1,8-diazabicyclo (5,4,0) -undesen-7 (commonly known as DBU). An amine salt, an imidazole compound such as 2-ethyl-4-methylimidazole, triphenylphosphine or a phosphonium salt may be used. The weight ratio of the curing accelerator to the total solid (composition) when used is less than 20% by weight, preferably 0.1 to 10% by weight.

(alcohol)
The alcohol used in the present invention preferably has a boiling point lower than the curing reaction temperature of the epoxy resin, preferably 100 ° C. or lower, more preferably 90 ° C. or lower, and further 80 ° C. or lower. Methanol (boiling point: about 64 ° C), ethanol (boiling point: about 78 ° C), 1-propanol (boiling point: about 97 ° C), 2-propanol (boiling point: about 82 ° C), 1-butanol (boiling point: about 117 ° C) , 2-Butanol (boiling point: about 100 ° C), isobutanol (boiling point: about 108 ° C), t-butanol (boiling point: about 83 ° C), hexanol (boiling point: about 157 ° C), cyclohexanol (boiling point: about 161 ° C) ) Etc. can be mentioned. The alcohol may be a mixture. However, although the above boiling point is the boiling point under atmospheric pressure, in the present invention, a drying treatment for removing or reducing the amount of alcohol from a solid containing modified lignin, an epoxy compound and alcohol may be performed under reduced pressure. When the drying treatment is performed under reduced pressure, the above boiling point may be the boiling point under reduced pressure. Alcohol having 5 or less carbon atoms is more preferable. Alcohols having 3 or less carbon atoms (methanol, ethanol, propanol) are particularly preferable from the viewpoint of meltability and ease of removal, and ethanol is particularly preferable from the viewpoint of safety. With high boiling point organic solvents such as dimethylformamide, N-methylhydride, and polyethylene glycol of the prior art, it is difficult or impossible to remove the solvent below the epoxy curing temperature under normal pressure. Further, even under reduced pressure, it is difficult to quickly remove the solvent below the epoxy curing temperature due to the high boiling point, and further, in these solvents that need to be dissolved once above the curing temperature, the curing reaction does not occur. The solvent cannot be removed or reduced by the drying operation.

The thermosetting resin composition powder of the present invention most preferably does not contain residual alcohol, but the residual amount of alcohol is preferably 20% by weight or less based on the weight of the composition. It may be preferably 10% by weight or less, 5% by weight or less, and further 1% by weight or less. The smaller the alcohol content is, the more preferable it is in terms of process control of melting, molding, heat curing and physical properties of the obtained cured product. In one embodiment, the alcohol content is 1% by weight or more, and further 3% by weight or more. It may be. The content of the organic solvent in the composition can be measured from the weight change of the modified lignin before and after treatment with alcohol before drying, and after drying and pulverization, the weight is reduced below the epoxy curing temperature in thermogravimetric analysis. It can be estimated as a minute. The residual amount of alcohol is 1% by weight or less, and most preferably 0% by weight.

Further, the thermosetting resin composition powder of the present invention does not need to contain an organic solvent other than alcohol, and preferably does not contain it. However, other organic solvents may be contained as long as the characteristics of the thermosetting resin composition powder of the present invention are not impaired. The content of the organic solvent other than alcohol is preferably as small as possible, and is preferably 15% by weight or less, 5% by weight or less, 1% by weight or less, and particularly preferably 0% by weight.

(Thermosetting resin composition powder)
The thermosetting resin composition powder of the present invention is an uncured product, and by reheating, it can be brought into a molten state again even at a temperature lower than the curing reaction temperature of the modified lignin and the epoxy compound. The melting temperature is preferably lower than the curing reaction temperature of the modified lignin and the epoxy compound, more preferably 100 ° C. or lower, still more preferably 80 ° C. or lower, but molding is performed in a sufficiently short time after melting. If it can be processed, there is no problem even if it is remelted at a temperature equal to or higher than the epoxy curing temperature. The thermosetting resin composition powder can be heated and melted, molded, and then heated to a temperature equal to or higher than the curing reaction temperature to produce a thermosetting plastic molded product. Further, the thermosetting resin composition powder can be directly heat-press molded to produce a thermosetting plastic molded body.

The particle size of the thermosetting resin composition powder (uncured product) of the present invention is not limited, but may be, for example, an average particle size of 1 μm to 10 mm, 5 μm to 5 mm, or 10 μm to 2 mm.

The thermosetting resin composition powder of the present invention uses modified lignin chemically modified with polyethylene glycol as a lignin raw material, and is once treated with alcohol to increase the mixability with the epoxy compound to be polymerized, and the mixture thereof. Is done uniformly and easily. The modified lignin and the epoxy compound are liquid phase mixed and mixed at the molecular level. No solid epoxy compound as a raw material remains in the mixture. In addition, the solvent in the resin raw material, which hinders a simple molding method and lowers the physical properties of the cured product, has already been removed. Furthermore, since it can be stored in the form of a resin precursor just before curing, the mixing process with the epoxy compound and the curing reaction process are completely separated, and at the same time at the final molding stage at the plastic molded product manufacturing site. It is a resin raw material powder that can be polymerized.

The thermosetting resin composition powder of the present invention is an uncured mixture of a modified lignin from which most or all of alcohol has been removed and an epoxy compound, and has not reached the curing temperature of the epoxy compound. It is a raw material (resin raw material powder that can be stored) that can be stocked until just before heat curing, and since the heat mixing and curing processes can be separated, the plastic manufacturing process can be made efficient.

Since the thermosetting resin composition powder of the present invention does not contain alcohol as a solvent or has a low content thereof, an extra step for evaporating a large amount of solvent in the melting and molding steps before curing. Not only is the production efficiency excellent, but it also has the effect of facilitating process control for manufacturing the plastic molded body.

Since the thermosetting resin composition powder of the present invention is a powder, when a plastic molded body is manufactured, it is cured by filling it in a molding mold and heating it at the manufacturing site to mold the plastic. The body can be easily manufactured. Further, when producing a fiber reinforced plastic, the composition is mixed with artificial fibers such as glass fibers or laminated with artificial fibers and melted by heating to impregnate the fibers with resin, and a pre-cured fiber resin such as prepreg is used. Complexes can be made. Further, it is possible to produce a plastic molded product containing the inorganic additive powder and having the function added by heating and curing the inorganic powder as an additive to the plastic and a simple powder as the powder. As described above, the thermosetting resin composition powder of the present invention is easy to use as a resin raw material and has excellent production efficiency in the molding and curing steps when manufacturing a plastic molded body.

Although it is considered that the thermosetting resin composition powder of the present invention does not contain alcohol or has a small content thereof, and is considered to be the result of the above-mentioned process advantages, the thermosetting resin of the present invention The thermosetting plastic (molded body) produced from the composition powder as a raw material has excellent hardness, and the lignin content can be increased as compared with the conventional corresponding products.

(Method for producing thermosetting resin composition powder)
In the method for producing a thermosetting resin composition powder of the present invention, a modified lignin chemically modified with polyethylene glycol is treated with alcohol to prepare an alcohol-containing modified lignin solid, and the alcohol-containing modified lignin solid is prepared. Is heated and mixed with an epoxy compound to obtain a mixture containing a modified lignin, an epoxy compound and an alcohol, and the obtained mixture is dried to remove or reduce alcohol, and then pulverized to obtain a modified lignin and an epoxy compound. To obtain a thermosetting resin composition powder containing.

By treating the modified lignin in the presence of alcohol, especially by heating, solids (aggregates) of the modified lignin incorporating the alcohol are produced in the liquid alcohol, and this alcohol-containing modified lignin solid When the product is mixed with an epoxy compound, it is easily mixed in liquid phase even at a low temperature as compared with modified lignin which is not treated with alcohol.

With the exception of methanol, alcohols do not react with modified lignins at room temperature and do not mix in liquid phase or form the above aggregates, but by raising the temperature of modified lignins in the presence of alcohols, especially with modified lignins Even when heated to a temperature lower than the curing reaction temperature with the epoxy compound, preferably 100 ° C. or lower, and further 80 ° C. or lower, the powder raw material of the modified lignin is gradually isomerized from the surface by alcohol and once liquefied with high viscosity. The liquefied modified lignin then gradually begins to aggregate and finally separates from the excess alcohol to produce a highly viscous or solid modified lignin composition. Alcohol is partially incorporated and remains in this composition. The same action proceeds at room temperature without heating methanol, and modified lignin separates and precipitates in methanol after liquefaction to obtain highly viscous aggregates. It may be optionally cooled to room temperature or lower to promote aggregation.

This alcohol treatment may be performed by operating in the air in a constant temperature bath, but it is preferable to use a stirrer equipped with a stirring blade, a shaking stirrer, a homogenizer, or the like.

The mechanism of formation of solids (aggregates) of modified lignin produced by alcohol-treating modified lignin is not clear, but in the end, almost all of the modified lignin raw material added can be aggregated and taken out. Although it becomes liquid, it is interpreted that the properties of the modified lignin have changed, such as the isomerization reaction of the modified lignin due to the interaction with alcohol, which increases the mixing property with different substances such as epoxy compounds. Therefore, it is understood as a complex mechanism of action such as the interaction between the modified lignin molecule and the alcohol solvent molecule and the swelling and melting that occur in the process.

The resulting aggregate can be separated from the remaining alcohol (supernatant). This aggregate is a solid modified lignin composition containing modified lignin and residual alcohol. In the alcohol-containing solid modified lignin composition, it was confirmed by infrared absorption analysis that the modified lignin and the alcohol did not chemically react with each other. Although not intended to be bound by theory, the modified lignin is isomerized by alcohol adsorption, coordination, swelling, etc., that is, the spatial arrangement of each atom or atomic group of the skeleton and branching or functional group of the modified lignin. It is considered that the change is such that when mixed with the modified lignin epoxy compound, the liquid phase is easily mixed at a lower temperature than before the alcohol treatment.

The mixed weight ratio of the modified lignin and the alcohol when treating the modified lignin with alcohol is not limited, and the excess alcohol can be separated as a supernatant after the modified lignin aggregates, so that the alcohol is larger than the modified lignin. It may be excessive, but for example, it may be in the range of 50 parts by weight to 50 parts by weight to 50 parts by weight to 10 parts by weight, and may be in the range of 50 parts by weight to 50 parts by weight to 50 parts by weight to 20 parts by weight. You may.

The solid modified lignin composition, which is a homogeneous mixture (aggregate) of modified lignin and alcohol, is separated from the supernatant, and when mixed with the epoxy compound, a curing accelerator is optionally mixed and mixed at the same time and cooled. Then, a solid thermosetting resin composition (uncured product) containing the modified lignin, the epoxy compound, the residual alcohol and optionally the curing accelerator can be obtained. The temperature for melt-mixing with the epoxy compound may be a temperature lower than the curing reaction temperature of the modified lignin and the epoxy compound, preferably 100 ° C. or lower, more preferably 80 ° C. or lower. For melt mixing, it is preferable to use a stirring device equipped with a stirring blade, a shaking stirring device, a homogenizer, or the like. In this solid thermosetting resin composition (uncured product), the modified lignin, the epoxy compound, and optionally the curing accelerator are in a liquid phase mixed state. The liquid-phase mixed state means that the powder is mixed at the molecular level, but it can be confirmed by the fact that the raw material epoxy compound powder used for the mixing does not remain as a solid substance.

The solid thermosetting resin composition (uncured product) thus obtained contains a large amount of residual alcohol solvent as it is, and foaming marks due to evaporation of residual alcohol are generated in the plastic during the heat curing treatment, which deteriorates the quality of the plastic. It takes a long time and process control to remove alcohol. In the present invention, the thermosetting resin composition is further subjected to a drying treatment (alcohol evaporation treatment) to remove alcohol contained in the thermosetting resin composition, or at least reduce it. This drying treatment may be performed under reduced pressure (drying under reduced pressure for lowering the boiling point), heating, ventilation, or a combination thereof. By reducing the pressure, the boiling point of the alcohol to be evaporated is lowered or the saturated vapor pressure is increased to facilitate or promote the evaporation of the alcohol at a temperature lower than the curing reaction temperature, and at a temperature lower than the curing reaction temperature. A drying treatment with reduced pressure is preferred because it facilitates the removal or reduction of alcohol. The temperature of the drying treatment may be a temperature lower than the curing reaction temperature of the modified lignin and the epoxy compound, preferably 100 ° C. or lower, more preferably 80 ° C. or lower. If the temperature is lower than the curing reaction temperature, the curing reaction does not proceed, so that alcohol can be removed or reduced without curing the thermosetting resin composition. The drying treatment (alcohol evaporation treatment) is preferably performed at a temperature lower than the curing temperature of the epoxy compound under reduced pressure and temperature rise. This drying treatment is not performed after the thermosetting resin composition is once produced (cooled) as described above, but the solid modified lignin separated from the supernatant liquid in the process of producing the thermosetting resin composition described above. At the stage of melt-mixing the composition with the epoxy compound, heating may be continued as it is before cooling, and optionally combined with reduced pressure or the like.

In the drying treatment of the thermosetting resin composition (uncured product), alcohol may be removed or reduced, and the resulting dry solid material may be pulverized to produce a powder, and the alcohol content after the drying treatment is sufficient. The amount is not limited, but for example, it is preferably 20% by weight or less, more preferably 5% by weight or less, more preferably 1% by weight or less, based on the weight of the thermosetting resin composition, and the content. Is particularly preferably 0% by weight.

The thermosetting resin composition (uncured product) thus obtained can be brought into a molten state again at a temperature lower than the curing reaction temperature of the modified lignin and the epoxy compound by reheating itself as it is. However, according to the present invention, the thermosetting resin composition (uncured product) obtained after the drying treatment becomes a brittle solid because the solvent, that is, most or all of the alcohol is removed and dried. , It was found that it can be easily crushed. The thermosetting resin composition powder is obtained by pulverization. The crushing treatment method is not particularly limited, and can be crushed lightly with a mixer or a mortar, and may be selected from a grinder, a ball mill, or the like. When vacuum drying is not performed, drying and pulverization (powdering) may be efficiently performed with a rotary pot mill, a rotary kiln, or the like in which warm air is circulated at a temperature at which the uncured material does not melt. The particle size of the powder is not limited, but for example, the average particle size may be 1 μm to 10 mm, more preferably 10 μm to 1 mm.

The thermosetting resin composition powder thus obtained uses modified lignin chemically modified with polyethylene glycol as a lignin raw material and is treated with alcohol so that the mixture with the epoxy compound to be polymerized is uniform (liquid phase mixing). It's easy. In addition, the solvent in the resin raw material, which hinders a simple molding method and lowers the physical properties of the cured product, has already been removed. Furthermore, since it can be stored in the form of a resin precursor immediately before curing, the mixing process with the epoxy compound and the curing reaction process are completely separated, and the resin raw material powder that can be polymerized at the plastic molding site (on-site polymerization). Type).

This thermosetting resin composition powder is an uncured mixture of a modified lignin from which most or all of alcohol has been removed and an epoxy compound, and has not reached the curing temperature of the epoxy compound. Therefore, it is molded and heat-cured. It is a raw material (resinable raw material powder that can be stored) that can be stocked until just before the above, and since the heat mixing and curing processes can be separated, the plastic manufacturing process can be made efficient.

(Manufacturing method of thermosetting plastic molded body)
By heating the thermosetting resin composition powder of the present invention, the powder is once melted, any residual organic solvent is removed, and then cured to produce a thermosetting plastic molded product. ..

When the thermosetting resin composition powder of the present invention is heated, the hydroxyl group in the modified lignin molecule and the epoxy group in the epoxy compound molecule directly react to polymerize and cure. The heating is usually selected from 65 to 200 ° C., preferably 80 ° C. to 150 ° C. or 100 ° C. to 150 ° C. for about 2 to 60 hours. Further, by using a powder in which a catalyst for accelerating the curing reaction is mixed in advance, a short time of about several minutes may be sufficient, especially when curing is performed at the same time during press molding.

When the thermosetting resin composition powder of the present invention is heated, it is preferably cured at 65 to 200 ° C., particularly at 80 ° C. to 150 ° C. for about 2 to 60 hours, with an HB or higher or a shore hardness of 50 or higher. Can obtain a thermosetting plastic molded body (also called a thermosetting plastic) having a shore hardness of 70 or more. The shore hardness of a thermosetting plastic can be measured with a conical indenter (D type) using a plastic durometer with respect to a plastic sample after heat curing. According to the present invention, the plastic molded product has an excellent thermosetting having the same hardness as the conventional product (for example, shore hardness 73) using polyethylene glycol as a solvent even at a high concentration such as 90% by weight of lignin. I was able to get plastic.

If the content of alcohol contained in the thermosetting resin composition powder is small, the step of removing the residual solvent required by the conventional method is shortened or becomes unnecessary, so that the time for heating and melting before thermosetting is increased. Not only can it be shortened, but process control such as melting, molding, and curing is easy, and the quality of the obtained plastic molded body can be improved.

In one embodiment of the present invention, a thermosetting resin composition powder is filled in a molding mold, then heated and melted again, and optionally gradually raised in heating temperature to be heat-cured, thereby molding a thermosetting plastic. The body can be manufactured.

In another aspect of the present invention, a thermosetting resin composition powder is directly filled in a molding mold and heat-pressurized to perform molding and heat-curing at the same time, for example, a thermosetting plastic molded body. Thermosetting plastic plates can be manufactured.

In another aspect of the present invention, a thermosetting plastic molded product can be produced by mixing or combining a thermosetting resin composition powder with a fiber, molding the mixture, and heat-curing the powder.

A plastic molded body containing artificial fibers such as glass fiber, carbon fiber, and propylene fiber is known as a fiber reinforced plastic (FRP) molded body.

Further, the thermosetting resin composition powder (unreacted mixture) of the present invention can be impregnated with various artificial fibers to prepare a prepreg. Further, the prepreg or the laminate of the unreacted mixture solid and the artificial fiber woven fabric can be processed by heat molding. The ability to use prepreg or unreacted mixture solid / artificial fiber woven laminates with thermosetting resins is a typical hand lay-up and vacuum impregnation method in the production of FRPs with thermosetting resins. In comparison, it has process saving properties. As the fiber structure, glass fiber, carbon fiber, polypropylene fiber and the like are suitable.

In another embodiment of the present invention, a thermosetting plastic having the function of an inorganic powder is added by mixing a thermosetting resin composition powder with another functional inorganic powder, molding the mixture, and heat-curing the powder. A molded body can be manufactured. For example, a flame retardant plastic can be easily produced by heating and curing the inorganic powder of a flame retardant such as silica, aluminum hydroxide, magnesium hydroxide, and antimony oxide after a simple mixing of the powders. The amount of the inorganic powder mixed depends on the density of the substance and the effect of flame retardancy, but is preferably in the range of 0 to 90% by weight, particularly preferably 10 to 50%. In the prior art of dissolving modified lignin in a solvent at high temperature, it is necessary to mix the inorganic powder with the highly viscous resin liquid immediately after dissolution, which causes problems such as sedimentation and aggregation, and difficulty in adjusting the powder content. However, in the present invention, the dispersibility can be improved by performing sufficient uniform mixing of the powders with each other in advance at room temperature with a pot mill or the like.

The thermosetting plastic produced by heat-curing using the thermosetting resin composition powder according to the present invention as described above is a thermosetting plastic, but is heated again to a temperature equivalent to the heat-curing temperature. It was observed that it showed thermoplasticity.

The thermosetting plastic molded product of the present invention can be used for effective utilization of woody biomass resources as a plastic member for home appliances, automobiles, OA equipment, a sealing material for piping, an adhesive sheet, and the like.

Next, the present invention will be specifically described based on Examples, but the present invention is not limited to these Examples.
In the following, as the modified lignin, one obtained by an acid solvolysis method using polyethylene glycol having a molecular weight of 400 as a solvent was used. Commercially available methanol, ethanol, 1-propanol, 1-butanol, cyclohexanol and 1-hexanol (all of which are special grades) were used as the solvent for dissolving the modified lignin, and commercially available bisphenol A type was used as the epoxy compound.

(Reference example 1)
When modified lignin powder was mixed with various alcohols such as methanol, ethanol, and 1-propanol, no reaction occurred at room temperature except for methanol, but the modified lignin gradually began to liquefy when heated to 70 ° C. .. Liquefaction started in the same way with methanol without heating. The liquid, which had increased fluidity, gradually aggregated and began to separate from alcohol. When cooled to room temperature, a dumpling-like mass separated from alcohol could be obtained. The details of the dumpling-shaped mass prepared using ethanol were examined thereafter. When the ratio of alcohol to the dumpling-shaped mass was determined from the weight difference between the modified lignin added and the recovered modified lignin after aggregation, the alcohol content was about 30% by weight. For example, dumpling-like masses of 49.99 g to 75.16 g of modified lignin were obtained.

FIG. 1 shows a photograph of the case where ethanol is used. Even if modified lignin is added to ethanol, the modified ethanol does not dissolve in ethanol (Fig. 1 (a)), but when heated in an oil bath at 70 ° C, it gradually darkens and begins to precipitate (Fig. 1 (b)). ), A sticky lignin dumpling-like aggregate is obtained (Fig. 1 (c)), and by removing the ethanol supernatant, it is possible to remove the isomerized solid lignin (Fig. 1 (d)). .. FIG. 2 is a photograph showing the same situation when various alcohols are used.

FIG. 3 shows an infrared absorption spectroscopic chart measured by using a general-purpose infrared spectrophotometer (Spectrum 100 manufactured by Perkin Elmer) for each of the modified lignin and the aggregate-like mass of the modified lignin. In the chart of the aggregated mass of modified lignin, absorption of modified lignin as a raw material and absorption of alcohol (ethanol) were observed, respectively, and it was confirmed that the modified lignin after aggregation treatment had no change in the basic chemical structure. Was done.

(Reference example 2)
Of Reference Example 1, for those using ethanol as a representative, residual ethanol is removed by decantation to take out a lump, and bisphenol A and modified lignin are mixed at a weight ratio of 1: 1 to about 80 ° C. When heated in, a highly fluid liquid mixture could be obtained again in a few minutes. When this liquid mixture was poured into an aluminum mold and heated at 120 ° C. for 24 hours, a hard epoxy cured product having a shore hardness of 70 could be obtained.

(Reference example 3)
A dumpling-shaped mass of modified lignin containing ethanol prepared in the same manner as in Reference Example 1 was mixed with bisphenol A at a weight ratio of 1: 1 with the modified lignin, and when it was continuously heated at 80 ° C., residual ethanol was produced. Gradually evaporated and gradually decreased in fluidity to give a solid mixture of modified lignin and bisphenol A. The alcohol content of this solid was about 1-5% by weight. This solid substance was once cooled and taken out, then placed in an aluminum mold and heated at 120 ° C. for 24 hours to melt it, and then hardened after forming an aluminum mold. As a result of infrared absorption analysis, the cured modified lignin resin (epoxy cured product) was epoxide as shown in FIG. 4 (b), which is an enlarged chart of a wave number of 700 to 1000 cm- ¹ in FIG. 4 (a). It was confirmed that the absorption based on the group (wave number 914 cm ^-1 ) was remarkably reduced, and that the curing reaction proceeded sufficiently. Moreover, the epoxy cured product had a shore hardness of 70 as measured by a durometer.

(Example 1)
A dumpled mass of modified lignin containing ethanol prepared in the same manner as in Reference Example 1 is mixed with bisphenol A at a weight ratio of 1: 1 with the modified lignin (FIG. 5 (a)) and continued to be heated at 80 ° C. Then, the remaining ethanol gradually evaporated, and the fluidity gradually decreased to obtain a solid mixture consisting of modified lignin and bisphenol A. When this solid is further dried under reduced pressure in a vacuum desiccator using an oil rotary pump at 80 ° C., the solid mixture melts with foaming (Fig. 5 (b)), and the foaming subsides when ethanol is almost removed. It solidified to form a solid foam (Fig. 5 (c)). This foam was brittle and could be easily pulverized in a mortar and obtained as a modified lignin / epoxy mixed powder before heat curing (FIG. 5 (d)). Similar to Reference Example 2, this powder was also heated in an aluminum mold at 120 ° C. to melt and then harden into a mold shape. In FIG. 6, the powder is placed in a mold (FIG. 6 (a)) and heated to 110 ° C. on a hot plate to melt and form a mold (FIG. 6 (b)), which is heated at 130 ° C. for 12 hours. Later, a mold-shaped cured resin was obtained (FIG. 6 (c)).

(Example 2)
In the same manner as in Example 1, the ratio of modified lignin to bisphenol was adjusted so that the modified lignin was 60% by weight, 70% by weight, 80% by weight, 90% by weight, 95% by weight, and 100% by weight. As a result, a uniform resin (plastic) having a glossy feeling could be obtained up to a modified lignin content of 90% by weight, and the shore hardness reached 72 to 76. When the amount of the modified lignin was 95% by weight or more, the particles were exposed and the resin became a brittle resin having lost homogeneity, and the hardness decreased. Shore hardness was measured by a durometer. 7 (a) to 7 (f) show photographs of plastics prepared from thermosetting resin composition powders having different mixing rates (indicated in the figure) of the modified lignin produced in Example 2. ..

(Comparative Examples 1 to 6)
For comparison, a commercially available epoxy resin using bisphenol A and phthalic anhydride (Comparative Example 1), a PEG solvent with bisphenol A / modified lignin = 1.3 (weight ratio) in the same manner as in Reference Examples 1 to 3. Epoxy cured product (Comparative Example 2), acrylic resin commercial product (Comparative Example 3), Teflon commercial product (registered trademark) (Comparative Example 4), polyethylene terephthalate (PET) commercial product (Comparative Example 5) prepared by dissolving in , Polypropylene (PP) commercial product (Comparative Example 6) was measured with a durometer. The PET commercial product (Comparative Example 5 was measured by stacking 15 plates having a thickness of 0.4 mm), and the PP commercial product (Comparative Example 6) was measured by stacking 7 plates having a thickness of 1 mm.

The shore hardness was 84 (Comparative Example 1), 72 (Comparative Example 2), 76 (Comparative Example 3), 54 (Comparative Example 4), 73 (Comparative Example 5), 54 (Comparative Example 6), respectively. .. In the conventional method of Comparative Example 2, when the amount of modified lignin was increased to reduce the weight ratio of bisphenol A / modified lignin to 1 or less, the liquid phase mixing of modified lignin and bisphenol A did not proceed sufficiently and the curing reaction was insufficient. Only a very brittle solid substance was obtained, and it cracked during the hardness measurement, making it impossible to measure.

(Example 3)
A glass fiber composite epoxy cured product was obtained by impregnating a glass fiber woven fabric with a liquid obtained by heating the powder prepared in the same manner as in Example 1 at 80 ° C. and heating at 120 ° C. for 24 hours. Further, a solid mixture composed of modified lignin and bisphenol A was superposed on a glass fiber woven fabric and heat-pressed from above to obtain a glass fiber composite epoxy cured product.

(Example 4)
It was confirmed that the sheet-shaped thermosetting modified lignin resin molded body produced in the same manner as in Example 1 was thermosetting, but when heated to 120 ° C. after curing, the sheet was deformed into a cylindrical shape. When cooled to room temperature, it remained cylindrical and hardened. Therefore, this thermosetting modified lignin resin molded product has thermoplasticity even though it is a thermosetting plastic. 8 (a) and 8 (b) are photographs showing the state of thermoplasticity of the resin sheet obtained by thermosetting the thermosetting resin composition powder.

(Example 5)
Using methanol, 1-propanol, 1-butanol, cyclohexanol, 1-hexanol instead of ethanol, a thermosetting resin composition powder containing a modified lignin and an epoxy compound was prepared as in the examples. Then, a thermosetting modified lignin resin molded body is produced.

The thermosetting resin composition powder and the thermosetting plastic molded product of the present invention can be used effectively as woody biomass resources as plastic members for home appliances, automobiles, OA equipment, sealing materials for piping, adhesive sheets, etc. Can be done.

Claims (13)

A thermosetting resin composition powder containing a modified lignin chemically modified with polyethylene glycol and an epoxy compound. The thermosetting resin composition powder according to claim 1, which is an in-situ polymerization type thermosetting resin composition powder. The thermosetting resin composition powder according to claim 1 or 2, further containing alcohol and having an alcohol content of 5% by weight or less. The thermosetting resin composition powder according to claim 1 or 2, which does not contain alcohol. Modified lignin chemically modified with polyethylene glycol is treated with alcohol to prepare an alcohol-containing modified lignin solid, and the alcohol-containing modified lignin solid is heated and mixed with an epoxy compound to obtain the modified lignin and the epoxy compound. A mixture containing alcohol is prepared, and the mixture is dried to remove or reduce alcohol, and then pulverized to obtain a thermosetting resin composition powder containing a modified lignin and an epoxy compound. A method for producing a thermosetting resin composition powder. The method for producing a thermosetting resin composition powder according to claim 5, wherein the drying treatment is performed under reduced pressure and temperature rise. The method for producing a thermosetting resin composition powder according to claim 5 or 6, wherein the residual alcohol content of the mixture is reduced to 5% by weight or less by a drying treatment. The method for producing a thermosetting resin composition powder according to claim 5 or 6, which does not leave residual alcohol in the mixture in the drying treatment. The thermosetting resin composition powder according to any one of claims 1 to 4 or the thermosetting resin composition powder produced by the production method according to any one of claims 5 to 8. , A method for producing a thermosetting plastic molded product, which comprises heating and melting in a mold and curing to obtain a thermosetting plastic molded product. The thermosetting resin composition powder according to any one of claims 1 to 4 or the thermosetting resin composition powder produced by the production method according to any one of claims 5 to 8. , A method for producing a thermosetting plastic molded product, which comprises filling a mold with heat and pressure molding as it is, and then heat-curing to obtain a thermosetting plastic molded product. The thermosetting resin composition powder according to any one of claims 1 to 4 or the thermosetting resin composition powder produced by the production method according to any one of claims 5 to 8. , A method for producing a thermosetting plastic molded product, which comprises molding and heat-curing by mixing with fibers or in combination with a fiber structure. The thermosetting plastic according to claim 11, wherein the thermosetting resin composition powder is heated and melted at a curing temperature or lower, impregnated into a fiber fabric, cooled to prepare a prepreg, and then heat-press-cured in an arbitrary shape. Manufacturing method of molded body. The thermosetting resin composition powder according to any one of claims 1 to 4 or the thermosetting resin composition powder produced by the production method according to any one of claims 5 to 8. , A method for producing a thermosetting plastic molded product, which comprises mixing with an inorganic powder, molding, and heat-curing.