JPH04106105A - Production of composite molding material - Google Patents

Abstract

PURPOSE:To obtain a composite molding material which can give a molding excellent in appearance and strengths by reacting a resin material with a powder of a plant under agitation. CONSTITUTION:A composite molding material is obtained by reacting a resin material (desirably a phenolic resin, a melamine resin or a furan resin) with a powder (having a mean particle diameter of desirably several mum to 3000mum) of a plant such as a tree, a grass, a bamboo or the like.

Description

[Detailed description of the invention] [Industrial application field]

The present invention is a composite molding material containing 2M powder. !
! This is a change in the method of delivery.

[Conventional technology]

Large amounts of naturally occurring trees, bamboo, grass, and rice husks are produced every year, and some of them are used for various purposes, but most of them are discarded due to their low utility value. For example, in the case of wood, the xylem is used as building material, etc., but the current situation is that most of the branches, bark, and leaves are discarded. Furthermore, even when wood is used as a building material, it has problems such as being easily combustible and easily deformed due to large dimensional changes due to moisture absorption. As one solution to these problems, synthetic wood is provided.Synthetic wood is obtained by mixing a resin binder and wood powder to prepare a molding material, and then molding this. This makes it possible to crush and effectively reuse wood that would otherwise be discarded, and since it contains resin as a binder, problems with flammability and dimensional changes can be improved. In preparing such a molding material, conventionally, for example,
This is done by putting wood powder into a kneader, adding resin such as powdered phenol resin, a hardening agent, and a suitable solvent, kneading it well, then discharging it, and pulverizing it after volatilizing the solvent. Alternatively, instead of a kneader, a Henschel mixer is used to knead, cool, and grind at high speed.

[Problem to be solved by the invention]

However, when kneading and mixing resin and wood powder as described above, it is difficult to mix the resin and wood powder uniformly, and a molding material with non-uniform resin and wood powder is prepared. As a result, appearance defects such as stains may occur on the surface of the molded product in areas with a large amount of resin.
There is a problem in that the strength of the molded product varies greatly between areas with a large amount of resin and areas with a small amount of resin, and the overall strength may become insufficient due to the effects of the areas with a small amount of resin. The present invention has been made in view of the above points, and provides a method for producing a composite molding material that can uniformly mix plant powder and resin and that can produce molded products with excellent appearance and strength. The purpose is to provide

[Means to solve the problem]

The method for producing a composite molding material according to the present invention is characterized in that when reacting resin raw materials to prepare a molding material, the resin raw materials are reacted while being mixed with powder of plants such as wood, grass, and bamboo. 9 In the present invention, the type of resin is not particularly limited, but includes phenol resin, melamine resin,
Furan resins and urea resins are preferred. The present invention will be explained in detail below. In the present invention, as the plant powder, in addition to wood powder, crushed plants such as bamboo, grass, leaves, roots, rice straw, and rice husks can be used, and these may be one or two types. A mixture of more than one species can be used. Among these, synthetic wood can be produced by using wood powder. The particle size of this plant powder is not particularly limited, but the average particle size is several μm to 3 μm.
000 μm is preferred. Next, the case where a phenol resin is used as the resin in the present invention will be explained. In the case of phenolic resin, phenols and formaldehydes are used as resin raw materials, and a phenolic resin-based composite molding material is prepared by reacting the phenols and formaldehydes while mixing them with plant powder in the presence of a catalyst. be able to. In the present invention, phenols mean phenol and phenol derivatives, and for example, in addition to phenol, there are trifunctional ones such as -cresol, resorcinol, and 3,5-xylenol, and four-functional ones such as bisphenol A and dihydroxydiphenylmethane. Functional ones, O-cresol, p-cresol, p-terbutylphenol, p-phenylphenol, p-cumylphenol,
Bifunctional 0- or P-substituted phenols such as p-nonylphenol, 2.4- or 2.6-xylenol can be mentioned, and halogenated phenols substituted with chlorine or bromine can also be used. be able to. Of course, in addition to selecting and using one type from these, it is also possible to use a mixture of multiple types. Further, as formaldehyde, formalin in the form of an aqueous solution is most suitable, but it is also possible to use forms such as rose formaldehyde, and in addition, part or most of the formaldehyde can be replaced with furfural or furfuryl alcohol. is also possible. Furthermore, as a reaction catalyst, basic substances that generate -NCH2- bonds between the benzene nuclei of phenols, such as hexamethylenetetramine, ammonia, methylamine, dimethylamine, ethylenediamine, monoethanolamine, etc. Primary and secondary amines, etc. can be used. Furthermore, in combination with these, basic catalysts commonly used in the synthesis of phenolic resins, such as alkali metal or alkaline earth metal hydroxides and tertiary amines, can also be used. These phenols, formaldehydes, and a reaction catalyst are placed in a reaction container such as a reaction pot, and the phenols and formaldehyde are reacted. At this time, plant powder is further added to the reaction container, and in the presence of this plant powder, A reaction between phenols and formaldehyde is carried out. Moreover, the blending ratio of phenols and formaldehydes is preferably set so that the molar ratio of phenols to formaldehydes is in the range of 0.5:1 to 1:3.5. Furthermore, when reacting phenols and formaldehydes in the presence of plant powder as described above, this reaction is carried out in the presence of an amount of water sufficient to at least stir the reaction system. When phenols and formaldehydes are reacted in water in the presence of plant powder with stirring in this way, at the beginning of the reaction the reaction system is viscous mayonnaise-like and becomes fluid upon stirring. As the reaction progresses, the condensation reaction product of phenols and formaldehyde containing plant powder gradually begins to separate from the water in the system, and the particles consisting of the phenol resin and plant powder produced by the reaction suddenly fill the reaction vessel. It becomes distributed throughout. After the mixed particles of plant powder and phenolic resin are dispersed and generated in this way, the reaction of the phenolic resin is further advanced to the desired degree, and when stirring is stopped after cooling, the particles settle and separate from the water. be done. These particles are in the form of fine spherical powder and can be easily separated by taking them out of the reaction vessel and subjecting them to some conditions. By drying this, it is possible to obtain a powdery material that is a composite molding material of phenolic resin and plant powder. The particle size of this powder or granular material is not particularly limited, but
It is generally desirable to adjust the thickness to a range of about 5 μm to 4000 μm. Next, a case where a melamine resin is used as the resin in the present invention will be explained. In other words, in the case of melamine resin, melamines and formaldehydes are used as resin raw materials, and the melamines and formaldehydes are reacted while being mixed with M powder in the presence of a catalyst, in the same manner as in the case of phenol resins. In this way, a powder or granular material that is a composite molding material of melamine resin and plant powder can be prepared. As the melamine, melamine or its derivatives can be used, and as the formaldehyde, those mentioned above can be used. An acid or an alkali can be used as a catalyst. Furthermore, in the case of furan resin, a composite molding material of furan resin and vegetable powder can be prepared by using furan as a resin raw material and reacting the furan while mixing it with vegetable powder in the presence of a catalyst. can. As the furan, furfuryl alcohol or the like can be used, and as the catalyst, an acid or the like can be used. In the case of this furan resin, it is generally not possible to prepare spherical particles like the above-mentioned phenol resins and melamine resins, so it must be used by freeze-drying or the like. Since the composite molding material is prepared by mixing and reacting the resin raw material with the powder of plants such as wood, grass, bamboo, etc. as described above, the vegetable powder is obtained by polymerizing the resin raw material. It will be evenly dispersed with the resin,
In addition, resin raw materials such as monomers permeate the plant powder, making it possible to obtain a composite molding material in which the plant powder is also impregnated with resin6.In addition, when preparing the composite molding material as described above, , using inorganic fillers together,
The resin can also be modified with a flame retardant or the like. In addition, plant powder contains a large amount of lignin and phenols, which react with formaldehyde and other substances to form polymers, resulting in a higher than theoretical amount of resin in the composite molding material. This means that a strong molded product can be obtained. The composite molding material obtained as described above has good moldability, and can be molded and used by any method such as injection molding, compression molding, transfer molding, or extrusion molding. Here, since the plant powder is uniformly dispersed in the composite molding material according to the present invention, a molded article in which the resin and the plant powder are uniformly dispersed can be obtained. In addition, when mixing plant powder, if it is kneaded into resin as in the past, the plant powder will be compressed during mixing and the bulk specific gravity of the molding material will increase, making it difficult to mold a molded product with a low specific gravity. Although it is difficult to do this, since there is no need for kneading in the present invention, the bulk specific gravity of the composite molding material is small, making it possible to mold a molded product with a low specific gravity. Furthermore, if the plant powder is mixed by kneading as in the conventional method, the resin is only coated on the surface of the plant powder, and the plant powder itself does not lose its original properties, such as moisture absorption, corrosion, termites, etc. However, in the present invention, since the plant powder is impregnated with resin, the plant powder itself does not absorb moisture, corrode, or suffer from damage caused by termites, etc. This will reduce the possibility of For example, when wood powder is used as plant powder, it can be formed into a square or board shape as synthetic wood and used for building materials such as doors, wall materials, ceiling materials, columns, etc., or it can be used as a laminated decorative board. It can be used for furniture, cabinets for electrical appliances, interior materials for automobiles, etc. Like natural wood, this synthetic wood can be easily cut with a saw and nailed, and because it contains resin as a binder, it absorbs less moisture and is less susceptible to dimensional changes and corrosion due to water. At the same time, there is little damage caused by termites, etc. Therefore, it can be well used for external walls and piles of houses, window frames, wooden bricks, railroad ties for trains, etc.

【Example】

Next, the present invention will be specifically explained using examples. 1. The moisture content in the reaction vessel is 11 qq, and the average particle size is 53 μm.
450 parts by weight of wood flour, 120 parts by weight of phenol, 3
132 parts by weight of 7% formalin, 3500 parts by weight of water,
15 parts by weight of hexamethylenetetramine and hexamethylenetetramine were added, and the mixture was heated to 85° C. over 60 minutes while being mixed and stirred, and then allowed to react for 180 minutes. By reacting in this way, a powdery substance consisting of wood flour and phenol resin was produced in the reaction system. Next, it was cooled to an internal temperature of 40°C, separated and air-dried, and the moisture content was 5%.
A powder-like composite molding material having a resin content of 15% and a bulk specific gravity of 0.14 was obtained. The molding flow of this product is 2.3cm2/g
Met. Here, the molding flow is determined by placing 5g of molding material on a press set at 160°C, applying a molding pressure of 121°C to the press surface and holding it for 3 minutes, then measuring the area of the molded product that has spread. Expressed as a number divided by . In addition, the moisture content was measured using the Karl Fischer method.
The bulk specific gravity was measured according to JIS K 6721. Fire lid ■1 In the reaction vessel, 450 parts by weight of wood flour with a moisture content of 11% and an average particle size of 53 μm, 370 parts by weight of phenol, 37%
400 parts by weight of formalin, 3,800 parts by weight of water, and 48 parts by weight of hexamethylenetetramine were charged, and the mixture was heated to 85° C. over 60 minutes while being mixed and stirred, and then allowed to react for 120 minutes. By reacting in this way, a powdery substance consisting of wood flour and phenol resin was produced in the reaction system. Next, it was cooled to an internal temperature of 40°C, separated in a furnace and air-dried, and the moisture content was 3.2%.
A powder-like composite molding material having a resin content of 45% and a bulk specific gravity of 0.22 was obtained. The molding flow for this product is 11. ．． 5c■2
/g. Comparison 1: In a reaction vessel, 100 parts by weight of phenol, 60 parts by weight of 379° formalin, and 1 part by weight of oxalic acid were charged and reacted under reflux, emulsified, and reacted for an additional hour, followed by dehydration at normal pressure. After that, the internal temperature was raised to 180℃ and 10
By dehydrating under reduced pressure at 0 torr, discharging the water when it reaches 190°C, and pulverizing it in a bottle mill,
A phenolic resin powder having a softening point of 100°C was obtained. next,
The Henschel mixer has a moisture content of 11% and an average particle size of 5.
Add 1125 parts by weight of 3 μm wood flour, 1 part by weight of the above phenol resin powder, 20 parts by weight of hexamethylenetetramine, add 150 parts by weight of methanol while stirring, and knead further until the internal temperature reaches 70°C. When the temperature reaches 100%, it is taken out, cooled, and pulverized to give a moisture content of 8.5%, a resin content of 15%, and a bulk specific gravity of 0.5%.
No. 21 powder-like composite molding material was obtained. The molding flow for this product is 2. It was lc1/g. Le Yi ■Schenschel mixer has a moisture content of 11% and an average particle size of 5.
Add 88 parts by weight of xamethylenetetramine to 1125 parts by weight of 3 μm wood flour and 730 parts by weight of the above phenolic resin powder obtained in Comparative Example 1, and further knead by adding 150 parts by weight of methanol while stirring. When the internal temperature reaches 70°C, it is taken out, cooled, and crushed to obtain a water content of 55% and a resin content of 452o.
A powder-like composite molding material having a bulk specific gravity of 0.36 was obtained. The molding flow of this product was 10.5 cs'/g. Composite molded material f obtained in Example 1.2 and Comparative Examples 1 and 2 above
182 g was placed in a mold having a cavity of length x ellipse = 130> and 150 mm, and heat and pressure molding was performed for 10 minutes using a press previously set at 160°C so that the molding thickness was 3 mm. The surface appearance of the thus obtained molded plate was observed with the naked eye, and the surface hardness was determined using the JIS standard.
Dimensional stability was evaluated by measuring the Rockwell hardness according to J7S A 5908 and measuring the water absorption thickness expansion coefficient according to J7S A 5908. The results are shown in the table below. Also, from this molded plate, width 10 mm and length 1:
Seven 30 mm test pieces were cut out, and the bending strength and bending modulus were measured, respectively. The results are shown in the following table. In the following table, the bending strength and bending modulus are shown as the average values of seven test pieces. Further, the differences between the maximum and minimum values of the bending strength and bending modulus of the seven pieces are shown in the following table as variations in bending strength and variations in bending modulus, respectively. The following is confirmed from the results in the table. As can be seen from the comparison between Example 1 and Comparative Example 1, and the comparison between Example 2 and Comparative Example 2, it is confirmed that the composite molding materials of each Example can be manufactured with a small bulk specific gravity. (2) In each of the examples, the wood powder was uniformly dispersed in the composite molding material, so it was confirmed that there were no stains on the surface of the molded product and that it had high dimensional stability. ■In addition, in the example, the wood powder is uniformly dispersed in the composite molding material, so there are small variations in bending strength and bending elastic modulus, and therefore the bending strength and bending elastic modulus are also excellent. That is [acknowledged]. [Effects of the Invention] As described above, in the present invention, when reacting resin raw materials to prepare a molding material, the resin raw materials are reacted while being mixed with plant powder such as wood, grass, bamboo, etc. The plant powder is uniformly dispersed with the resin obtained by polymerizing the resin raw material, and it is possible to manufacture a composite molding material in which the plant powder and resin are evenly mixed. It is possible to mold a dispersed molded product, and it is possible to obtain a molded product with excellent appearance, strength, etc. In addition, since there is no need to perform kneading when mixing the plant powder, it is possible to prepare a composite molding material with a low bulk specific gravity, and it is possible to obtain a lightweight molded product.

Claims (1)

[Claims] (1) A method for producing a composite molding material, which is characterized in that when preparing a molding material by reacting a resin raw material, the resin raw material is reacted while being mixed with powder of plants such as wood, grass, and bamboo.