JPS60199616A - Manufacture of onyx-looking product - Google Patents

Abstract

PURPOSE:To obtain an beautiful onyx looking appearance by adding a hardening agent to a mixture of a composition as a copolymerizing syrup of a specific monomer whose refractive index is specified in the solidified form at the room temperature and aluminum hydroxide at a specified ratio to be injected into a mold to solidify. CONSTITUTION:A hardening agent is added to a mixture of 80-15wt% of a compolimerizing syrup comprising two or more kinds of monomers selected from among cyclohexyl methaacrylate, methyl methaacrylate, 2-ethylhexylacrylate and styrene in such a manner that the refractive index will be 1.51-1.55 in the solidified form at the room temperature and 20-85wt% of aluminum hydroxide containing no organic substance with the average partical size of 3-50 micron and injected into a mold to solidify integrally. The solidified matter provides a hard and beautiful onyx-looking product which appears transparent with a flame resistance and pollution resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION Flame-retardant articles made of polymerizable syrupy aluminum hydroxide mixtures of methyl methacrylate poured into molds and allowed to solidify are known as architectural decoration materials. This is an astronomical stone-like product that scatters light beautifully, but its transparency is extremely low, making it difficult to express the onyx-like appearance, and because methyl methacrylate has high water absorption, durability deteriorates due to moisture absorption. There are some difficulties. The present invention is a comonomer of monomers with 2 ai or more selected from cyclohexyl methacrylate, 2-ethylhexyl (meth)acrylate, styrene, and methyl methacrylate, which have a lower water absorption than a homopolymer of methyl methacrylate. Onyx, which is characterized by adding a hardening agent to a mixture of aluminum hydroxide and a composition whose refractive index at room temperature is 1.51-1.55 when solidified with syrup, and injecting the mixture into a mold and solidifying the mixture. The present invention relates to a method for manufacturing an article having excellent transparency in appearance and durability with low water absorption.

The polymerizable chives used in the present invention have a solidified refractive index of 1.
A small amount of polymerization initiator and chain transfer agent were added to a mixture of two or more of the above monomers so that the ratio was 51 to 1.55, and the mixture was heated at an appropriate temperature to reach a predetermined viscosity. If so, you can add a polymerization inhibitor to a cold monomer of the same composition and rapidly cool it to stop the polymerization, or you can copolymerize the monomer mixture in advance using a suspension polymerization method. It can be produced by dissolving it in a monomer mixture of the same composition. The proportion of monomers in the copolymerizable syrup is, for example, 2-
Ethylhexyl (meth)acrylate 1o~40! The initial refractive index target can be reached by selecting the amount in the range of 30-60% by weight of MMA, 20-60% by weight of cyclohexyl methacrylate, and 10-50% by weight of styrene.

The refractive index greatly affects the appearance of the product, and when it is smaller than 1.51, the light transmittance decreases and the material looks like astronomical stone.
If it exceeds this, the transparency becomes too great and it loses its solidity. Therefore, unless the refractive index is within the range of 1.51 to 1.55, it is difficult to obtain the beautiful onyx-like appearance that is the object of the present invention. As the monomer ratio of cyclohexyl methacrylate and styrene increases, the water absorption level will be lowered as much as possible, but it will also become harder and more brittle.

2-Ethylhexyl (meth)acrylate has a small water absorption rate and is useful for imparting sinterability, but if it is too large, the Tg will be low, so the above range is desirable.

It is advantageous to add a small amount of polyfunctional (meth)acrylate monomer to the copolymerizable syrup to increase the solidification rate.

The aluminum hydroxide preferably has an average particle size of 3 to 50 microns and does not substantially contain organic matter.

If the particle size is smaller than this range, the viscosity of the mixture with the silica will be high and the transparency will be poor. It causes uneven thickness and dispersion, and settles without waiting for solidification.

It is desirable that the viscosity distribution be as close-packed as possible. Furthermore, if organic substances are contained, the whiteness will decrease, so it is necessary that they be substantially free of organic substances. The amount used is 20"85% by weight in view of flame retardancy and workability.

Curing agents include polymerization initiators and accelerators. Suitable initiators are organic peroxides, such as diacyl peroxides, peroxy esters, hydroxy peroxides, ketone peroxides. Hydroxy peroxide and ketone peroxide are used in combination with an accelerator at a temperature that does not adversely affect the cured product, such as foaming6.
Polymerization can be promoted at a low temperature of 0° C. or lower, and quaternary ammonium salts or a combination of quaternary ammonium salts and soluble metal salts are preferred as they cause less coloring. The general formula of the quaternary ammonium salt is R9 3 Groups I Ra and R4 are respectively methyl, ethyl or benzyl groups.Metallic soaps include C
Examples include naphthenic acid salts and hexoic acid salts such as u I Mn l Fe, Ni, and Sn. The amount of initiator to be used is 0.5 to 3 parts by weight based on 1,100 parts by weight of Shiloh 71, and the amount of accelerator to be used is 0.001 to 0.05 part by weight to effectively act. When metal salts are combined, the metal content is 0.0001 to 0.
Approximately 0.03 parts by weight is suitable.

Various colorants may also be used in the present invention.

Suitable materials include metal oxide powder and hydraulic powder.

For example, there is alumina cement, which exhibits the coloring properties of natural stone.

Example 1 A monomer exchange consisting of 50% by weight of styrene monomer and 50% by weight of methyl methacrylate monomer was carried out. When the predetermined temperature was reached, 0.35 parts by weight of thioglycolic acid was added, followed by 0.04 parts by weight of azoisobutyronitrile to start the first cup, and the internal temperature was increased at 1-1.5°C/min. The temperature was raised to 90°C, kept as it was, and after adding the initiator, 6 (after 1 minute, 35N parts of a cold monomer composition was added over 2 minutes to cool and stop the polymerization, and the non-volatile content was 28%, the viscosity was 5 voids). A copolymerizable syrup of styrene-methyl methacrylate was prepared.The solid state of this syrup had a refractive index of 1.54 at room temperature.

This copolymerizable syrup contains 1 part, 9 parts, and lauryl trimethylammonium chloride (concentrated 11 fiO%) infrohanol mwxn! 9. Manganese naphthenate (Mn content 6
%) 0.59 and octene acetic acid Kobal) (Co content 8%) 0.059 were added and dissolved well. Then cyclohexanone peroxide l.

g was added and dissolved. Add 1.5 kg of aluminum hydroxide with an average particle size of 6 to 9 microns to this syrup composition, mix well, and after defoaming, pour into a mold of 30 boxes x 40 bags x 1.2 bags. )℃. Contents are 6-7
The fever ended in an hour. Thereafter, it was heated to 80° C. for 2 hours to complete curing. The solidified product was a light beige, onyx-like, transparent, flame-resistant, stain-resistant, hard, and beautiful article.

Example 2 Cyclohexyl methacrylate 40it'N.%.

A terpolymerizable syrup was prepared as in Example 1 using a monomer composition consisting of 4% by weight of methyl methacrylate and 8% by weight of 20% styrene monomer.

The refractive index of this solidified syrup at room temperature is 1.52
Met.

0.6 dimethylaniline per 1 kg of this copolymerizable syrup
．． 9 Add 3 g of tobenzoyl peroxide and dissolve well, add 1.7 kg of aluminum hydroxide with an average particle size of 14 microns to this syrup composition, mix thoroughly, and after defoaming 30G11L x 40 an x 1.2 c
The mixture was injected into a m(i7) type and allowed to stand at 20-3°C (1°C).

The contents stopped exothermic in 5-6 hours. Thereafter, it was heated to 80° C. for 2 hours to complete curing. The solidified product is a pale yellow, hard and beautiful article with a translucent appearance of OEX 14, 1II flammability, and 1 stainability.

Example 3 3 n17 uik parts of methyl methacrylate, 40 parts of 2-ethylhexylnucuacrylate, and 1 itl
Manufactured. The refractive index of the cured product from this shop is 1. i
i 3 Te1> Tsuta. Add the curing agent system of Example 2 to 1 kg of this syrup and stir well. 2. Next, add 1.5 kg'r of aluminum hydroxide with an average particle size of 6 to 9 microns to this syrup composition and mix well. Defoaming completed [again. Thereafter, it was heated at about 100° C. for 2 hours to perform second half curing. The solidified product was a beautiful product with a pale beige color and onyx-like transparency, flame resistance, and impact resistance.

Comparative Example 1 Fruit/llll1fl using only methyl methacrylate
A sheet of MMA homopolymer was prepared as described above. This syrup contained about 30 vol of polymethyl methacrylate, had a viscosity at room temperature of about 5 poise, and had a refractive index of the solidified product at room temperature of 1.49.

A curing agent and aluminum hydroxide were mixed with this syrup in the same proportion as in Example 2 and hardened in the same manner to obtain a flame-retardant plate. Although this material was scattered in an astronomical stone-like appearance, it did not exhibit onyx-like transparency.

Comparative example'・2 Methyl methacrylic +y-to 30 heavy barge and styrene 7
0 parts by weight of copolymerizable white whelk was prepared. The refractive index of this solidified syrup at room temperature was 1.56.

A hardening agent and aluminum hydroxide were added to this syrup in the same manner as in Example 2, and the same method was used to harden it to obtain a flame-retardant plate.This material had a transparency of 75:5.

It lacked solidity and was hard but brittle.

Patent applicant: Takeo Yamaguchi, agent of Nippon Sensei Kagaku Kogyo Co., Ltd.

Claims (1)

[Claims] 1. The refractive index of the solidified product is 1.51-1.55 at room temperature. A composition of 20 to 85% by weight of aluminum hydroxide, which is micron in size and substantially free of organic matter, selected from cyclohexyl methacrylate, methyl methacrylate, 2-ethylhexyl (meth)acrylate and styrene is added to the mold. A method for manufacturing an article with an onyx-like transparent appearance and excellent water resistance and stability, which is characterized by injecting into the interior and solidifying L.