JPH01195027A - Method for molding synthetic resin - Google Patents

Abstract

PURPOSE:To obtain a molded body low in a coefficient of thermal expansion and a heat shrinkage factor and having good heat resistance, by molding fillers to form a molded product in such a state that the fillers are bonded to each other and impregnating the molded body with a resin solution becoming a matrix to cure the impregnated one. CONSTITUTION:Each of fillers to be suitably used has a fibrous or flaky shape and a large aspect ratio of 3 or more, pref., 5 or more. These fillers are preparatorily molded into a required shape at first. As the preparatory molding method, a paper-making method, a compression method or a press method is utilized. Subsequently, the preparatorily molded product composed of said fillers is impregnated with a resin solution becoming a matrix to cure the impregnated one. This matrix resin solution must be easy to penetrate in the fine reticulated gaps of the preparatorily molded product and pref. has low viscosity and pref. contains a resin of relatively low MW at the time of an uncured state. The impregnation of the matrix resin solution is performed by an autoclave method.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method of molding a synthetic resin that is suitably used as a material for kitchen counters, etc. The present invention relates to a method of molding a synthetic resin that is suitably used as a material for kitchen counters, etc. After forming the product,
By impregnating and curing the matrix resin liquid, a molded article with particularly good heat resistance can be obtained.

[Prior Art] One of the synthetic resin moldings conventionally used for kitchen counters and the like is so-called artificial marble, as shown in FIG. When manufacturing such artificial marble, there is a method in which a mixture of filling material such as aluminum hydroxide + A' 1 is mixed with matrix resin 2 such as acrylic resin is molded into a predetermined shape using a mold and hardened. was widely used.

[Problems to be Solved by the Invention] In the artificial marble manufactured by this method, each filler l is dispersed in the matrix resin 2 as shown in FIG. The condition is
There is no bonding force between each filler 1. Because of this, when this artificial marble is placed under heating conditions? This is because the flow due to the thermal expansion of the 7trix resin 2 proceeds freely, increasing thermal stress, resulting in problems such as cracks and cracks. In addition, since such artificial marble is molded using a mold during its manufacture, residual strain is often caused by the mold during molding, and if this residual strain is large, it may be damaged when heated. Inconveniences such as parts shrinking due to heat and cracks occur. That is,
There was a problem with poor heat resistance.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the two problems and provide a method for molding a synthetic resin, which yields a molded article with a small coefficient of thermal expansion and a small coefficient of thermal contraction, that is, a molded article with good heat resistance.

[Means for Solving the Problems] The present invention has a method of solving the problem by molding the filled material to form a molded product in which the fillers are bonded to each other, and then impregnating and curing the resin liquid that becomes the matrix. shall be.

The present invention will be described in detail below.

The fillers used in this invention include fibrous,
It has a flaky shape and has an aspect ratio of 3"-1 or more, preferably 5 or more"2, and is preferably used. Specifically, for example, wollastonite, potassium ditanate, gypsum fiber, xonotlite, oblique synthetic magnesium filler (MOS), slag fiber (PM
F), inorganic fillers such as sepiolite, mica, talc, and glass fiber.

These fillers are first preformed into the desired shape. For the preforming method, methods such as paper making method, consolidation method, pressing method, etc. may be used. Then, it is preferable to mold the obtained preformed product so that its bulk density is about 01 to 1.7 g/cm'' and its porosity is about 96 to 40%. Because shrines are made with relatively large aspect ratios, physical bonds or entanglements occur during molding, but in order to make these bonding points or bonding points more firmly bonded, various chemical treatments have been applied. You may also use a specific linking means. As a means of control, sled force,
Methods such as impregnating and solidifying metals (alcoquines, etc.) using a sol-gel method, or methods of heating and firing may be used. Furthermore, it is possible to improve the aesthetic appearance by mixing an appropriate coloring agent as necessary during preforming of this filler and molding it.This coloring agent includes dyes and pigments dissolved in a solvent. or a small amount of resin, such as a polyurethane resin, dissolved therein is preferably used.

Next, the preformed product made of this filler is impregnated with a resin liquid that will become the matrix 7 and hardened. This matrix resin liquid must be able to easily penetrate into the fine mesh-like voids of the preformed product, and because it has a low viscosity, the uncured state is a relatively low-molecular weight resin. is preferred. For example, a thermosetting resin initial condensate, a thermoplastic resin monomer, or a partial polymer thereof, etc., specifically, a low viscosity material such as methyl methacrylate (MMΔ) monomer, which is preferably a type that can be polymerized by heat. .

In addition to methacrylic resins, we also use low-viscosity products such as unsaturated polyester resins, diallyl phthalate resins, silicone resins, Evokin resins, polyurethane resins, and monomer-cast polyamide resins. It can also happen. In addition, if a transparent material such as methacrylic resin or polyester resin is used as the matrix resin liquid, the network structure of the filler will be visible as if it were a pattern, and the molded product will look different from the original. It's also effective.

In addition, impregnation with this 7 Trix resin solution can be carried out by an autoclave method, etc. For example, in an autoclave, after immersing the preformed product in the matrix resin liquid to impregnate it, if necessary, in a non-oxygen atmosphere, at room temperature to 200°C, normal pressure to 2 MPa. The impregnating resin liquid is hardened under heating and pressurizing conditions of approximately 1.

According to such a method, a molded article (J) having a network structure in which the fillings 1711 are chemically or physically bonded to each other as shown in FIG. Since it is impregnated with the matrix resin liquid 2 and cured, it is a filler with a small coefficient of thermal expansion.The J2 particles suppress the movement of the matrix resin 2, such as expansion or contraction. Its heat resistance is significantly better than that of artificial marble.In addition, since no mold is used during molding, residual strain caused by the mold does not remain in the molded product 3, and it can be placed under heating conditions. There is no inconvenience such as breakage or cracking due to heat deformation even when the material is heated.Also, since it has a network shape made of two-part filler material bonded to each other, it has a high strength. It is also superior to traditional artificial marble.

[Example] (Example I) Using fibrous walrus night as a filler, a high-density (10) plate-like preformed product with a thickness of 10 mm was formed by compression pressing.

This preform was mixed with methyl methacrylate (MMΔ) monomer liquid and 2% by weight of azobisisobutyronitrile (Δ
IBN) and placed in an autoclave.
After impregnating with Q-700mmHg for 20 minutes, further autoclave under nitrogen atmosphere at 60°C, 9.5at
It was cured under pressure conditions of m.

Here, the ratio of the filler to the MMΔ monomer was 37% by volume.

(Comparative example) A mixture of 38% by volume of a filler such as acrylic resin and aluminum hydroxide powder is poured into a plate-shaped mold and heat-molded at a temperature of 60°C to form the -1- resin. was cured to produce a 10 mm thick artificial marble.

Using a thermomechanical analysis device (T M
A) The thermal expansion coefficient was measured. Furthermore, the expansion/shrinkage ratios of the molded bodies of Examples and Comparative Examples ``-'' were similarly measured by TMA when the molded bodies were heated to 230°C and then returned to room temperature. These results are shown in Table 1.

Table 1 As is clear from Table 1, the molded articles of the embodiments of the present invention have a coefficient of thermal expansion of 1, I even though they contain the same amount of filler as conventional artificial marble. x, I
0-5 (1/'C), which is a very small value for a plastic material, lower than that of a phenol laminate. Furthermore, even after the treatment (230'C - room temperature), the molded articles of the examples did not shrink by 1゛ and only slightly expanded, indicating very good heat resistance. .

[Effects of the Invention] As explained below, the synthetic resin molding method of the present invention involves molding fillers to form a molded product in which the fillers are bonded together, and then adding a resin liquid to serve as a matrix. Since it is impregnated and cured, the resulting molded product is obtained by impregnating and curing the matrix resin liquid into a molded product with a network structure in which fillers are chemically or physically bonded to each other. Therefore, the filler particles having a small coefficient of thermal expansion suppress movements such as expansion or contraction of the matrix resin, resulting in good heat resistance. Furthermore, since a mold is not used during molding, residual strain caused by the mold will not remain in the molded product, and even if it is placed under heating conditions, there will be no inconvenience such as cracks or cracks due to thermal deformation. Furthermore, since it has the above-mentioned structure, it is superior to conventional artificial marble in terms of strength.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view schematically showing an example of a molded article produced by the method of the present invention, and FIG. 2 (J) is a schematic sectional view schematically showing an example of a conventional artificial marble. - Filler, 2... Matrix resin.

Claims (1)

[Claims] A method for molding a synthetic resin, which comprises molding fillers to form a molded product in which the fillers are bonded together, and then impregnating and curing the molded product with a resin liquid serving as a matrix.