JPH0730184B2 - Sheet and method for manufacturing molded article - Google Patents

Description

Detailed Description of the Invention a. Object of the Invention (Field of Industrial Application) The present invention relates to a method for producing a sheet and a molded product.

(Prior Art) Conventionally, as seen in JP-A-59-106932, as a method for binding solids, a binder composed of a prepolymer having an isocyanate group at the molecular end, an organic polyisocyanate or a mixture thereof is powdered. There is a method of adhering it to a granular or granular solid substance, spreading it on a substrate, and spreading it.

This binding method is carried out by reacting with moisture or added water in the air to form a resin or rubber-like prepolymer having an isocyanate group and an organic polyisocyanate, a pulverized product such as a polyurethane resin, or an organic matter such as wood chips. In addition, the surface active points of the inorganic solids react with each other and firmly adhere to each other, and in the case of this method, the molded product is hard.

(Problems to be solved by the invention) Moreover, in the case of this method, a large amount of a prepolymer having an isocyanate group as a binder is used with respect to a solid material, so that the product becomes expensive, and by this method, for example, a flowerpot, etc. In the case of manufacturing daily commodities, it is not possible to provide the product to general customers at low cost, and this method has a slow curing speed, so when it is made into a line and the product is obtained continuously, its mass productivity is poor, especially In the case of (1), blocking occurs and the releasability is extremely poor, so that there is a problem that causes the above-mentioned cost.

B. Structure of the Invention (Means for Solving the Problems) The present invention for achieving the above-mentioned object includes (A) a vegetable fine fiber or powder particles, (B) the following prepolymer, or the following prepolymer and block Equivalent to 10 to the weight of isocyanate and combination
NCO / OH equivalent ratio of 1.5 to 100 of 0 weight times of water, (C) (C-1) polyoxyalkylene polyol having 10 to 90% of oxyethylene chain in oxyalkylene chain, and organic polyisocyanate
The NCO prepolymer having a crosslink density of 1.00 or less per 1000 atomic weight (hereinafter referred to as prepolymer) reacted alone or (C-2) was rapidly cured at room temperature or under heating by using the prepolymer and a blocked isocyanate in combination. After that, it is a method for producing a sheet and a molded product, which is characterized by further pressurizing under heating.

In the prepolymer used in the present invention, polyoxyalkylene polyol is ethylene glycol, propylene glycol, hydroquinone, bisphenol A, 1.6-hexanediol, glycerin, trimethylolpropane, 1.2.6-hexanetriol,
For low molecular weight polyols such as pentaerythritol, α-methyl glycoside, sorbitol, sucrose, castor oil, and low molecular weight polyamines such as ethylenediamine, ethylentriamine, piperazine, methylamine, n-butylamine, aniline and xylenediamine. ,
It is a product obtained by addition-polymerizing ethylene oxide and a mixed alkylene oxide of alkylene oxide other than ethylene oxide and having 10 to 90% of oxyethylene chain in the oxyalkylene chain.

Such other alkylene oxide is propylene oxide,
Examples include butylene oxide, styrene oxide, and tetrahydrofuran.

In addition, 100% oxyethylene chains are solid at room temperature and are inconvenient to handle, and the flexibility of the formed sheet or molded product is poor. When the oxyethylene chain is 10% or less, the compatibility with water is poor and the physical properties of the product are poor.

When the mixed alkylene oxide is subjected to addition polymerization, the addition polymerization form may be random or block.

Next, the organic polyisocyanates are tolylene diisocyanate (TDI) and crude tolylene diisocyanate (C-TD
I), diphenylmethane diisocyanate (P-MDI),
Polymethylene polyphenyl isocyanate (C-MD
I), hexamethylene diisocyanate, xylene diisocyanate, naphthalene diisocyanate, isophorone diisocyanate, etc., alone or in a mixture.

The prepolymer according to the present invention is, for example, a urethane prepolymer composition obtained by reacting the polyoxyalkylene polyol with the organic polyisocyanate and containing substantially unreacted polyisocyanate groups. When reacting polyoxyalkylene polyol and organic polyisocyanate, the NCO / OH equivalent ratio is
It is 1.5 to 100, preferably 2 to 20.

The prepolymer must have a crosslinking density of 1.00 or less per 1000 atomic weight. When the crosslink density exceeds 1.00, the secondary workability becomes extremely poor as described later.

The crosslink density referred to in the present invention is calculated as follows, for example. That is, an active hydrogen atom-containing compound W ₁ g having a molecular weight NW ₁ and a functional group number F ₁ and a molecular weight Nw ₂ and a functional group number F ₂
k and an active hydrogen atom-containing compound W ₂ g of molecular weight NWn- _1, functional groups Fn- ₁ active hydrogen atom-containing compound Wn- ₁ and g, the molecular weight NWN, by reacting an organic polyisocyanate compound Wng of functionality Fn The crosslink density (CD) per 1000 atomic weight of the resulting polyurethane polymer is Calculated by

Next, as the blocked isocyanate according to the present invention, a blocked product of the prepolymer, a blocked product of the polyisocyanate monomer, or a terminal NCO prepolymer obtained by the reaction of a polyoxyalkylene polyol or polyester polyol other than the above with the polyisocyanate. Examples include blocked polymers.

Blocking agents for blocked isocyanates include sodium bisulfite, ε-caprolactam, imidazoles, phenol compounds, alcohol compounds, active methylene compounds, and other blocked isocyanates dissolved in a solvent or water to form a solution. Are preferred.

In particular, the method using an aqueous solution described in JP-A-58-63716 is preferable as the blocked product.

When the prepolymer and the blocked isocyanate are used in combination, the ratio is arbitrary.

The amount of the prepolymer alone, or the combined use of the prepolymer and the blocked isocyanate, may be wood waste, wood flour, fiber waste,
It is 1 to 100 parts by weight, preferably 5 to 20 parts by weight, based on 100 parts by weight of plant fine fibers such as buckwheat hulls, rice husks, wheat husks, rice straw, rice bran and soybean meal, or powder grains, and water is pre-treated. Equivalent to 100 times the weight of the polymer or combination, preferably 5 to 4
0 parts by weight.

The prepolymer, or prepolymer and block isocyanate, and excess water can be used by premixing the prepolymer or prepolymer with block isocyanate and excess water, and then adding the vegetable fine fibers, or prepolymer or prepolymer. And block isocyanate and excess water are simultaneously sprayed on the plant fine fibers, or the plant fine fibers are pre-wetted with excess water and then the prepolymer or prepolymer and block isocyanate are mixed. .

The prepolymer or prepolymer and blocked isocyanate are rapidly cured at room temperature or under heating. In the present invention, this is called primary processing.

In the case of the primary processing, the temperature is 0 ° C to 150 ° C, preferably 10 ° C to 50 ° C.

The sheet or molded product obtained by the above method can be further heat-processed.

The sheet or molded product that has been cured and bonded at room temperature or under heating is further pressed under heating to obtain the target sheet and molded product. In the present invention, this is called secondary processing.

In the case of this secondary processing, the temperature is 70 ° C to 200 ° C, preferably 100 ° C, and the pressure is ^{2 to} 100 Kg / cm ² , preferably 10 to 60 Kg / cm ² .

If the crosslink density of the prepolymer exceeds 1.00, the secondary processing becomes difficult.

In the production method of the present invention, a solvent, a plasticizer, an antifoaming agent, a surfactant, a colorant, an inorganic filler, a catalyst and the like may be used in combination, if necessary.

C. EFFECTS OF THE INVENTION In the production method of the present invention, for example, primary processing facilitates transportation, thus reducing transportation costs, and secondary processing can obtain a sheet or a molded article suitable for the purpose, particularly prepolymer alone or prepolymer. Secondary processing is also possible by using a polymer and a blocked isocyanate together. When used alone, a flexible sheet or molded product is obtained, and when used together, a relatively hard sheet or molded product is obtained.

(Example) (A) Synthesis of prepolymer: Various polyols (using glycerin, propylene glycol, ethylene glycol, etc. as starting materials, addition polymerized with ethylene oxide and / or propylene oxide) and various isocyanates (TDI, PM
DI, C-MDI) was reacted and then diluted with methyl ethyl ketone to obtain a prepolymer having a concentration of 70%.

The properties are shown in Table 1.

(B) Synthesis of Blocked Isocyanate; (B-1) 1 mol of trimethylolpropane and 3 mol of tolylene diisocyanate (2.4-, 2.6-isomer ratio 80:20) reacted to obtain a free isocyanate group content of 19.2. 100 parts by weight of triisocyanate at 4.7% by weight and 4.7 parts by weight of ethylene glycol (NCO / OH = 3) were reacted at 85 ° C. for 60 minutes to obtain 104.7 parts by weight of a urethane prepolymer having a free isocyanate group content of 12.24% by weight.

Next, 20.9 parts by weight of dioxane was added to 50.3 parts of p-nonylphenol.
71.2 parts by weight of a solution in which 1 part by weight is dissolved and 0.21 part by weight of triethylamine as a catalyst are added at 50 ° C., gradually heated, and reacted at 85 ° C. for 60 minutes to obtain a free isocyanate group content.
176.11 parts by weight of a solution of a 3.04% by weight (based on the prepolymer) of a partial block prepolymer in dioxane was obtained.

Next, after adding 27.9 parts by weight of 40% by weight taurine soda aqueous solution at 40 ° C, reacting at 40 to 50 ° C for 30 minutes, diluting by adding 350 parts by weight of water, and a translucent stable homogeneous aqueous solution having a solid content of 30% 55
3.9 parts by weight were obtained.

(B-2) Tris- (isocyanatehexyl) -buret polyisocyanate In a mixed solution of 100 parts by weight and dioxane 30 parts by weight, 5.6 parts by weight of ethylenediamine (NCO / NH ₂ = 3)
39.5 parts by weight of a mixed solution of 22.8 parts by weight of dioxane and dioxane were gradually added under cooling at 25 ° C. After the exotherm started, the mixture was gradually heated and reacted at 75 ° C. for 15 minutes to obtain 179.5 parts by weight of a prepolymer dioxane solution having a free isocyanate group content of 14.51% by weight.

Next, 52 parts by weight of a solution prepared by dissolving 30.9 parts by weight of ε-caprolactam in 21.1 parts by weight of dioxane and 0.21 part by weight of tetramethylpropylenediamine as a catalyst were added at 50 ° C., and at 85 ° C.
The mixture was reacted for 90 minutes to obtain 23.71 parts by weight of a dioxane solution of a partial block prepolymer having a free isocyanate group content of 3.71% by weight.

Next, after adding 34.3 parts by weight of 40% by weight taurine soda aqueous solution at 40 ° C, reacting at 40 to 50 ° C for 30 minutes, diluting with 485.1 parts by weight of water, and 751.1 parts by weight of a uniform aqueous solution having a solid content of 20% by weight. Obtained.

(B-3) A-1; 100 parts by weight of prepolymer, 8 parts by weight of imidazole, and 50 parts by weight of methyl ethyl ketone were reacted at 90 ° C. for 3 hours to obtain a blocked isocyanate.

Example 1. As the raw wood flour, cedar and ground flour discharged from a factory that saws cypress lumber are used, and the wood flour (water content is 5.9% by weight,
The particle size is 60 parts or less 20 parts by weight, 60 to 52 mesh 6.
7 wt%, 52-48 mesh is 5.3 wt%, 48 mesh or more is 68 wt% wood powder) 100 parts by weight, water 1000 parts by weight, prepolymer 20 parts by weight, blocked isocyanate 10 parts by weight are mixed at room temperature, This was pressed at a pressure of 50 Kg / cm ² to form a sheet. After drying at room temperature for 1 week, a pressure of 50 kg / cm ^{2 was} further applied and heat pressing was performed at 120 ° C. for 5 minutes to obtain a sheet having a thickness of about 3 mm.

The result of bending this primary processing sheet 90 degrees and the primary processing
The tensile strength of the secondary processed sheet was measured.

The results are shown in Table 2.

Example 2. 15 parts of terminal NCO prepolymer A-1 and 150 parts of water are premixed and then mixed with 100 parts of chaff within 20 seconds.

Immediately while spreading, it was spread in a mold to a thickness of about 20 mm and cured at 22 ° C.

Cured 3 minutes after mixing the terminal NCO prepolymer and water.

Then, after leaving it for 24 hours, apply a pressure of 20 Kg / cm ² at 100 ° C for 1
After hot pressing for 10 minutes, a 10 mm thick molded article rich in elasticity was obtained.

The physical properties were as follows.

Density… 0.50 g / cm ³ Tensile strength… Primary processing 410 g / cm ² Secondary processing 480 g / cm ² Bending strength… 28 Kg / cm ²

Claims (1)

[Claims] 1. An amount of (A) a vegetable fine fiber or a powder granule is equivalent to (B) the following prepolymer, or the following prepolymer and a block isocyanate and the weight of the combined use.
100 parts by weight of water, (C) (C-1) polyoxyalkylene polyol having 10 to 90% of oxyethylene chain in the oxyalkylene chain, and organic polyisocyanate are added in NCO / OH equivalent ratio of 1.5 to 100.
The NCO prepolymer having a crosslink density of 1.00 or less per 1000 atomic weight (hereinafter referred to as prepolymer) reacted alone or (C-2) was rapidly cured at room temperature or under heating by using the prepolymer and a blocked isocyanate in combination. After that, the method for producing a sheet and a molded product is characterized by further applying pressure while heating.