JPH0360864B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for producing a vegetable composite material. More specifically, the present invention relates to a method for producing a plant-based composite material that can be suitably used as a building material or as a tatami floor. [Prior Art] Conventionally, as a method for bonding organic or inorganic powder particles, etc., as disclosed in JP-A-59-106932, prepolymers having isocyanate groups at the molecular ends, A method is known in which a binder made of an organic polyisocyanate or a mixture thereof is adhered to powder particles, spread on a substrate, and spread under pressure. This bonding method uses a binder such as a prepolymer or organic polyisocyanate that has isocyanate groups that react with moisture in the air or added water to become resin-like or rubber-like, and a crushed material such as urethane resin or wood chips. The molded product obtained by this method has a high hardness. [Problems to be Solved by the Invention] However, the molded products obtained by this method have the disadvantage that they are brittle and have poor physical properties such as tensile strength and impact resistance. Furthermore, since the reaction rate between organic polyisocyanate and water is slow, even if the manufacturing process is integrated into a line to continuously manufacture products, the mass productivity is low. [Means for Solving the Problems] Therefore, the present inventors have conducted intensive research to solve these problems, and as a result, they have discovered a method for producing a plant-based composite material that can completely eliminate all of the above problems.
The present invention has now been completed. That is, the present invention comprises: (A) vegetable fine fibers and/or vegetable fiber powder; (B) an excess amount of water; and (C) (C-1) 10% by weight of oxyethylene chains in the oxyalkylene chains. % or more of polyoxyalkylene polyol or polyoxyalkylene monool and an organic polyisocyanate, and (C-2) a urethane prepolymer containing substantially unreacted NCO groups, or (C-2) a mixture of the urethane prepolymer and a resin emulsion. Relating to a method for producing a plant-based composite material, which is characterized in that the combination is cured at room temperature or under heating and molded in the presence of (D) a woven or non-woven fabric made of chemical fibers and/or natural fibers. . [Operations and Examples] The vegetable fine fibers and/or vegetable fiber powder (hereinafter referred to as vegetable fine fibers, etc.) used in the present invention include, for example, wood flour, wood chips,
Examples include fine fibers and powder particles such as cork powder, rice husks, wheat husks, rice bran, seed lees, bean meal, buckwheat husks, and rice straw, but these may be used alone or in combination of two or more. . The polyoxyalkylene polyol containing 10% (wt%) or more of oxyethylene chains in the oxyalkylene chain used in the present invention is:
For example, ethylene glycol, propylene glycol, hydroquinone, bisphenol A,
1,6-hexanediol, neopentyl glycol, glycerin, trimethylolpropane,
Low molecular weight polyols such as 1,2,6-hexanetriol, pentaerythritol, α-methyl glycoside, sorbitol, seurose, castor oil, or ethylenediamine, diethylenetriamine, piperazine, methylamine, n-
It is an addition polymerization of a mixed alkylene oxide of ethylene oxide and an alkylene oxide other than ethylene oxide to low molecular weight amines such as butylamine, aniline, and xylylene diamine, and contains 10% or more of oxyethylene chains in the oxyalkylene chain. preferably has a weight average molecular weight of 1000
These include the above-mentioned polyaddition reaction products. When ethylene oxide and other alkylene oxides other than the above-mentioned ethylene oxide are mixed, the mixing ratio is 10 to 100% in the oxyalkylene chain.
The proportion is preferably such that it contains oxyethylene chains. The polyoxyalkylene monool containing 10% or more of oxyethylene chains in the oxyalkylene chain used in the present invention includes, for example, monoalcohols such as methanol, ethanol, butanol, hexanol, octanol, phenol, cresol, and alkylphenol. , is an addition polymerization of alkylene oxide that is a mixture of ethylene oxide and other alkylene oxide other than ethylene oxide (hereinafter referred to as mixed alkylene oxide), and the oxyalkylene chain contains 10% or more, preferably 10 to 100% of oxyethylene. It is a reaction product that has units. Examples of alkylene oxides other than the ethylene oxide include propylene oxide, butylene oxide, styrene oxide, and tetrahydrofuran. The polyoxyalkylene polyol or polyoxyalkylene monool (hereinafter referred to as polyoxyalkylene mono(poly)ol) containing 10% or more of oxyethylene chains in the oxyalkylene chain has 10% oxyethylene units in the oxyalkylene chain. If it is less than that, the affinity with water will deteriorate, and the physical properties of the resulting sheet or molded product will also deteriorate. Further, when mixed alkylene oxides are subjected to addition polymerization, the form of the addition polymerization may be either random or block. Examples of the organic polyisocyanate used in the present invention include tolylene diisocyanate (TDI), crude tolylene diisocyanate (crude
TDI), diphenylmethane diisocyanate (MDI), polymethylene polyphenyl isocyanate (crude MDI), hexamethylene diisocyanate, xylene diisocyanate, naphthalene diisocyanate, isophorone diisocyanate, etc., but these may be used alone. More than one species may be used in combination. The urethane prepolymer containing substantially unreacted NCO groups (hereinafter referred to as urethane prepolymer) used as a binder in the present invention is obtained by reacting the polyoxyalkylene mono(poly)ol with the organic polyisocyanate. urethane prepolymers containing substantially unreacted NCO groups. When reacting polyoxyalkylene mono(poly)ol and organic polyisocyanate, the
NCO/OH equivalent ratio is 1.5-100, preferably 2-50
It is. If the value of the equivalent ratio is less than 1.5, the viscosity of the urethane prepolymer becomes high and workability becomes poor, and if it exceeds 100, the resulting resin becomes brittle. The resin emulsion used in the present invention includes, for example, one or more water-soluble resins selected from derivatives such as polyvinyl alcohol, polyacrylic acid, polyacrylamide, and maleic anhydride; natural rubber, styrene-butadiene rubber,
One or more natural rubbers selected from chloroprene rubber, acrylonitrile butadiene rubber, acrylate butadiene rubber, isoprene rubber, butyl rubber, and ethylene propylene rubber, synthetic rubber latex, or modified rubber latex thereof; polyvinylidene chloride, polyvinyl chloride , ethylene-vinyl acetate copolymer, polyacrylic acid ester copolymer, melamine, urea, urea-
Examples include emulsions of one or more synthetic resins selected from formalin, phenol, and resorcinol; water-based resin emulsions made of copolymerized modified synthetic resin emulsions or mixtures thereof, and the present invention is limited only to these resin emulsions. No, others can be used. Note that these may be used alone or in combination of two or more. The resin emulsion used is usually adjusted to have a resin concentration of 20 to 80%. By using a resin emulsion in combination with the prepolymer, the amount of prepolymer used can be reduced, and the total cost of the binder can be reduced. The chemical fibers used in the present invention include, for example, inorganic fibers such as metal fibers, glass fibers, rock wool, fibers, and carbon fibers; regenerated fibers such as cellulose-based and protein-based fibers; semi-synthetic fibers; polyamide-based and polyester-based fibers; , polyurethane type, polyethylene type, polystyrene type, polyvinyl chloride type, polyvinylidene chloride type, polyacrylic type, polyvinyl alcohol type, polymethylene-urea type and other synthetic fibers. Furthermore, examples of the natural fibers used in the present invention include vegetable fibers, animal fibers, and mineral fibers. These chemical fibers and natural fibers are usually used in the form of woven or non-woven fabrics. The size and thickness of the woven fabric and non-woven fabric are not particularly limited in the present invention, but usually,
It is preferable to use one adjusted to have a width of 1 to 2 m or a thickness of 0.1 to 3 mm. In the method for producing a plant-based composite material of the present invention, the above-mentioned (A) plant-based fine fibers and/or plant-based fiber powder, (B) an excessive amount of water, and (C) (C-1) the above-mentioned urethane. The prepolymer alone or (C-2) the combination of the urethane prepolymer and the resin emulsion is cured at room temperature or under heating in the presence of (D) a woven or nonwoven fabric made of chemical fibers and/or natural fibers. A composite material can be obtained by molding. The amount of the urethane prepolymer used is 100 parts (parts by weight) of vegetable fine fibers, etc., whether the urethane prepolymer is used alone or the urethane prepolymer and the resin emulsion are used together. 1 to 500 parts, preferably 5 to 100 parts. If the amount used is less than 1 part, the binding force as a binder will be insufficient, and if it exceeds 500 parts, characteristics such as vegetable fine fibers will be lost. Further, when the urethane prepolymer and the resin emulsion are used together, the amount of the resin emulsion used is preferably 1 to 500 parts, particularly 5 to 100 parts, per 100 parts of vegetable fine fibers. In this case, the ratio of the amount of the prepolymer to the resin emulsion used is not particularly limited, but is preferably 10 to 90 parts per 100 parts of the prepolymer. In addition, the amount of water used is 10 parts or more, preferably 50 to 500 parts, based on 100 parts of the total amount of the urethane prepolymer or the urethane prepolymer and synthetic resin emulsion. Use an excess amount of water than required.
By using an excess amount of water, it is possible to reduce the amount of urethane prepolymer used as a binder, which is advantageous in terms of cost, and since it acts as a mold release agent during molding, there is no need to use another mold release agent. There is no. Moreover, since this water also acts as a diluent, the resulting composite material has no stickiness or breathing on the surface compared to a method using a plasticizer as a diluent. The usage amount is 10
If the amount is less than 100%, the curing time of the urethane prepolymer becomes longer. Urethane prepolymer or urethane prepolymer and resin emulsion, such as vegetable fine fibers,
and how to mix excess water, e.g.
A method in which urethane prepolymer or urethane prepolymer, resin emulsion, and excess water are mixed in advance and then vegetable fine fibers are added; A method of spraying onto fine fibers, etc. includes a method of pre-wetting vegetable fine fibers with excess water, a method of mixing a urethane prepolymer or urethane prepolymer, and a resin emulsion, but the present invention is limited to these methods. It is not something that will be done. The woven fabric or nonwoven fabric needs to be added until the urethane prepolymer or the urethane prepolymer and resin emulsion is completely cured, and the woven fabric or nonwoven fabric may be added at the same time as the vegetable fine fiber etc. , or may be before or after. Further, the woven fabric or nonwoven fabric may be contained in, on, or below a sheet or molded product made of vegetable fine fibers or the like. Furthermore, a woven or nonwoven fabric may be sandwiched between the primary formed sheets and pressed under heat to form a secondary sheet. In the production method of the present invention, a solvent,
Plasticizers, antifoaming agents, surfactants, colorants, inorganic fillers, catalysts, flame retardants, fungicides, insecticides, discoloration inhibitors, etc. are added to 100 parts of urethane prepolymer.
It may be used within a range that does not exceed 100%. The urethane prepolymer or urethane prepolymer, synthetic resin emulsion, and excess water, such as the vegetable fine fibers, are mixed at room temperature or under heating, and the mixture is rapidly cured, but the temperature is usually 0 to 150°C. , preferably 10 to 50°C. When molding the mixture into a desired size, pressure molding may be performed, and the pressure is usually
It is 0.1-100Kg/ ^cm2 , preferably 0.1-50Kg/ ^cm2 . The temperature of the mold during molding may be at room temperature or may be heated. Next, based on manufacturing examples, working examples, and comparative examples,
The manufacturing method of the present invention will be explained in more detail. Production Examples 1 to 4 (Synthesis of urethane prepolymers) Using glycerin, sorbitol, hexanol, or ethylene diamine as starting materials, the polyoxyalkylene mono(polyoxyalkylene) shown in Table 1 was prepared by random addition polymerization of mixed alkylene oxides of ethylene oxide and propylene oxide. ) and organic polyisocyanate at the equivalent ratio shown in Table 1, and then diluted with ethyl acetate to give a concentration of 70%.
% of urethane prepolymer was obtained. Example 1 Ground flour discharged from a factory that saws cedar and cypress logs was used as wood flour, and this wood flour (moisture content: 5.9
%, particle size: 28% of 60 mesh or less, 6.7% of 60 to 52 mesh, 5.3% of 52 to 48 mesh, 68% of wood powder of 4.8 mesh or more) 1000 parts, 660 parts of water and as a binder in Production Example 1 Mix 100 parts of the selected urethane prepolymer within 20 seconds at room temperature (approximately 20°C) to make glass cheesecloth (wire diameter: 0.24 mm, basis weight: 65 g/
^m2 , density: vertical 8.3 lines/25mm, horizontal 8.3 lines/25mm)
Spread it on top to form a 5mm thick sheet and heat to 22℃.
After curing (10 minutes after application)
After 1 minute), the sheet was placed in a dryer set at 80° C. and dried for 1 hour to obtain a flexible sheet. Further, a pressure of 20Kg/cm ² was added and the temperature was 30℃ at 120℃.
Heat pressed for a second to obtain a 2.0 mm thick wooden boat with glass cloth. The physical properties of the obtained boat were measured based on the following measurement method. The results are shown in Table 2. (Hardness) Measured using a Shore A hardness meter. (Density) Measured according to JIS A5906. (Tensile strength) Measured according to JIS K6301. (Elongation at break) Measured according to JIS K6301. (Dimensional change after immersion in water) Measured according to JIS A5705. (Impact strength) Measured according to ASTM G-14. (Amount of deflection) A molded product with a thickness of 3 cm was measured according to JIS A5901. Example 2 A composite material was produced in the same manner as in Example 1, except that a resin emulsion was used, a wire mesh was used as a woven fabric or a non-woven fabric, and the amount of water added was changed. The physical properties of the obtained composite material were measured in the same manner as in Example 1. The results are shown in Table 2. Examples 3 and 4 Composite materials were produced in the same manner as in Example 1, except that the raw materials for the composite materials were adjusted to have the compositions shown in Table 2. Example 1 shows the physical properties of the obtained composite material.
It was measured in the same manner. The results are shown in Table 2. Comparative Examples 1-4 Composite materials were produced in the same manner as in Examples 1-4, except that woven fabric or non-woven fabric was not used in Examples 1-4. The physical properties of the obtained composite material were investigated in the same manner as in Example 1. The results are shown in Table 2.

【table】

【table】

[Table] [Effects of the invention] In the method for producing a plant-based composite material of the present invention, a large amount of water is used as a diluent for urethane prepolymer or urethane prepolymer and resin emulsion, and these are mixed in the presence of woven or nonwoven fabric. It has great strength because it can be evenly applied to vegetable fine fibers with little utility value such as wood flour, wood chips, cork powder, rice husks, rice bran, wheat husks, seed lees, bean meal, buckwheat husks, and rice straw. Flexible composite materials can be obtained at low cost.

Claims (1)

[Scope of Claims] 1. (A) Plant fine fibers and/or plant fiber powder, (B) Excess amount of water, and (C) (C-1) Oxyethylene chains in the oxyalkylene chains. A urethane prepolymer containing substantially unreacted NCO groups obtained by reacting a polyoxyalkylene polyol or a polyoxyalkylene monool containing 10% by weight or more with an organic polyisocyanate, or (C-2) the urethane prepolymer and A plant-based composite material characterized by being molded by curing a combination of a resin emulsion at room temperature or under heating, and molding it in the presence of (D) a woven fabric or non-woven fabric made of chemical fibers and/or natural fibers. manufacturing method.