JPH04170350A - Resin composition for scagliola for press molding - Google Patents

Abstract

PURPOSE:To improve transparency, surface smoothness and moldability by incorporating a specified filler into unsatd. polyester resin. CONSTITUTION:This resin compsn. is obtd. by blending 100 pts.wt. unsatd. polyester resin (A) consisting of 50-80wt.% unsatd. polyester and 50-20wt.% polymerizable monomer such as styrene with 150-350 pts.wt. filler (B) consisting of 70-95wt.% Al(OH)3 of <=10mum average particle size and 30-5wt.% Al(OH)3 of 30-50mum average particle size and a curing agent (C) such as t-butyl perbenzoate or by further adding a reinforcing agent, a shrinkage reducing agent, a curing accelerator, an internal releasing agent, a thickener, a colorant, etc., (D) as required.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a resin composition for artificial marble.
The present invention relates to an unsaturated polyester resin composition for press-molding artificial marble, which has excellent transparency and surface smoothness as well as excellent moldability.

(Prior art) Conventionally, various fillers were blended with unsaturated polyester resin,
The hardened molded product is widely used as artificial marble for bathtubs, sink counters, kitchen counters, tables, etc. These are manufactured by press molding using a sheet molding compound (hereinafter abbreviated as SMC), a bulk molding compound (hereinafter abbreviated as BMC), or the like.

In addition, various fillers have been used in the past, such as calcium carbonate, silica, and aluminum hydroxide. Among them, aluminum hydroxide It is well balanced and widely used.

Incidentally, in recent years, artificial marble has come to be required to have a high-class appearance represented by transparency and surface smoothness, but according to the method of press-molding SMC or BMC as described above, generally transparent It is not possible to obtain a molded product with good texture, surface smoothness, etc.

For example, in order to give the resulting molded product a sense of transparency, it is conventional to make the refractive index of the unsaturated polyester resin used as close to that of the filler as possible, or to reduce the amount of filler blended, and to Methods such as using a large one have been adopted, but satisfactory results have not yet been obtained.

On the other hand, in order to give the resulting molded product surface smoothness,
Conventionally, methods such as pressing a mold at a high temperature or using a filler with a small particle size have been adopted. However, according to this method, the molded product obtained does not have transparency.

Thus, according to conventional methods, it is difficult to obtain artificial marble that has both transparency and surface smoothness.

(Problems to be Solved by the Invention) The present invention has been made to solve the above-mentioned problems in the production of conventional artificial marble, and has excellent transparency and surface smoothness, as well as good formability. The object of the present invention is to provide an excellent unsaturated polyester resin composition for press molding artificial marble.

(Means for Solving the Problems) The resin composition for artificial marble according to the present invention contains 70 to 95% by weight of aluminum hydroxide with an average particle size of 10 μm or less and 3 parts by weight of aluminum hydroxide with an average particle size of 3
It is characterized by containing 150 to 350 parts by weight of a filler consisting of 30 to 5% by weight of aluminum hydroxide having a diameter of 0 to 50 μm.

The unsaturated polyester resin usually consists of 50 to 80% by weight of unsaturated polyester and 50 to 20% by weight of polymerizable monomer. When the unsaturated polyester content is less than 50% by weight, artificial marble with sufficient strength cannot be obtained, while when it exceeds 80% by weight, the moldability and workability of the resin composition deteriorate.

An unsaturated polyester resin can generally be obtained by reacting an acid component, which is an α,β-unsaturated dibasic acid and/or its acid anhydride, with a polyhydric alcohol component.

Examples of the α,β-unsaturated dibasic acids include maleic acid, fumaric acid, itaconic acid, citraconic acid, and chlormaleic acid, and two or more of these may be used in combination. Examples of polyhydric alcohols include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,3-butanediol, neopentyl glycol, 1,6-hexanediol, triethylene glycol, hydrogenated hisphenol A, and isopentyl. Glycol, glycerin, trimethylolpropane, dicyclopentadiene, etc. can be mentioned. These may also be used in combination of two or more.

In the production of unsaturated polyester resins, a saturated dibasic acid and/or its acid anhydride may be used in combination as the acid component, if necessary. Such saturated dibasic acids include
Examples include phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, succinic acid, azelaic acid, adipic acid, tetrahydrophthalic acid, hexahydrophthalic acid, chlorendic acid, tetrachlorophthalic acid, tetrabromophthalic acid, etc. can.

On the other hand, examples of polymerizable monomers include styrene, vinyltoluene, divinylbenzene, α-methylstyrene, chlorostyrene, dichlorostyrene, vinyl acetate, diallyl phthalate, diallyl isophthalate, diallyl terephthalate, etc., which are crosslinked with unsaturated polyester resins. Possible vinyl monomers, divinyl monomers, vinyl oligomers, etc. can be mentioned. Usually, styrene is preferably used.

In the resin composition for artificial marble according to the present invention, as an inorganic filler, 70 to 95% by weight of aluminum hydroxide having an average particle size of 10 μm or less, preferably 2 μm or more and an average particle size of 100 parts by weight of the unsaturated polyester resin are used. Diameter 3
150 to 350 parts by weight of a filler consisting of 30 to 5% by weight of aluminum hydroxide of 0 to 50 μm are used.

According to the present invention, by using a mixture of aluminum hydroxide with a small average particle size and aluminum hydroxide with a large average particle size in a predetermined ratio as a filler, the resulting molded product has a transparent appearance. and improve surface smoothness. In the above aluminum hydroxide mixture, when the proportion of aluminum hydroxide with an average particle size of 10 μm or less exceeds 95% by weight, the resulting molded product loses transparency;
When the proportion of aluminum hydroxide in m exceeds 30% by weight, the surface smoothness of the molded product obtained decreases.

Further, the amount of the filler is 100% of the unsaturated polyester resin.
If the amount is less than 150 parts by weight, the viscosity of the resin composition will be too low, resulting in poor press moldability;
If it exceeds 50 parts by weight, the filler will not be sufficiently dispersed, the resin composition will become lumpy, and press moldability will deteriorate.

The unsaturated polyester resin for artificial marble according to the present invention is
Usually contains a hardening agent, and if necessary, a reinforcing material,
Contains low shrinkage material, curing accelerator, internal mold release agent, thickener, coloring agent, etc.

As a curing agent, for example, t-butyl perbenzoate,
Organic peroxides such as benzoyl peroxide, methyl ethyl ketone peroxide, dicumyl peroxide, t-butylperoxy-2-ethylhexanoate, AG t-butylperoxycyclohexane, t-butylperoxyisopropyl carbonate, etc. used.

Examples of the reinforcing material include glass fibers, polyester fibers, phenol fibers, polyvinyl alcohol fibers, and carbon fibers, but glass fibers are usually preferably used.

In addition, examples of low shrinkage materials include polyethylene, polystyrene, polymethyl methacrylate, polyvinyl chloride,
Thermoplastic resins such as polyvinyl acetate, polycaprolactam, and saturated polyester, polybutadiene rubber, and polystyrene-acrylonitrile copolymers are used.

As the curing accelerator, metal salts of organic acids, particularly cobalt salts, such as cobalt naphthenate, cobalt octylate, cobalt acetylacetone, etc., are used.

As the internal mold release agent, higher fatty acids such as stearic acid and zinc stearate, higher fatty acid salts, alkyl phosphates, and the like are used.

Thickeners are substances that chemically bond with hydroxyl groups, carboxyl groups, ester groups, etc. possessed by unsaturated polyester, creating linear or partially cross-linked bonds to increase the molecular weight and thicken the unsaturated polyester resin. For example, diisocyanates such as toluene diisocyanate,
Metal alkoxides such as aluminum isopropoxide and titanium tetrabutoxide, divalent metal oxides such as magnesium oxide, calcium oxide, and bryllium oxide, and divalent metal hydroxides such as calcium hydroxide are used.

The resin composition for artificial marble according to the present invention is usually obtained by kneading the above-mentioned unsaturated polyester resin and a filler,
Furthermore, it can be obtained by mixing the above-mentioned curing agent and other materials such as a reinforcing material, a low shrinkage material, a curing accelerator, an internal mold release agent, a thickener, a coloring agent, etc. as necessary.

The resin composition for artificial marble according to the present invention is usually molded at a molding temperature of 120 to 160°C and a molding pressure of 0 to 140 kg.
Artificial marble can be obtained by press molding with /C4.

(Example) The present invention will be explained below with reference to Examples.

Examples 1 to 3 Using a mixture of aluminum hydroxide with an average particle size of 8 μm and 40 am as a filler, B having the composition shown in Table 1 was prepared.
Prepare MC, molding temperature 130°C, molding pressure 100
The molded product was molded under the conditions of "kgf/cgg" and a molding time of 7 minutes to obtain a flat plate with a thickness of 6 cm. The properties of this molded product are shown in Table 1.

Comparative Examples 1 to 3 Only one of aluminum hydroxide with an average particle size of 8 μm or 40 μm was used as a filler, or aluminum hydroxide with an average particle size of 25 μm was used as a filler.
BMC having the composition shown in Table 1 was prepared by using aluminum hydroxide with a thickness of 40 μm and molded under the same conditions as in Example 1 to obtain a flat plate with a thickness of 6 mm. The properties of this molded article are shown in Table 1.

As is clear from the results shown in Table 1, according to the resin composition of the present invention, molded articles with excellent transparency and surface smoothness can be obtained. It also has excellent moldability such as cutting workability.

(Effects of the Invention) As described above, the resin composition for artificial marble according to the present invention contains an unsaturated polyester resin and a predetermined ratio of aluminum hydroxide having a small average particle size and aluminum hydroxide having a large average particle size. Since the mixture is used as a filler,
Artificial marble with excellent transparency and surface smoothness can be obtained.

Therefore, such a resin composition is suitable for use in, for example, bathtubs, washroom counters, kitchen counters, tables, and the like.

Patent applicant Sekisui Chemical Co., Ltd. Representative Hiro 1) Kaoru

Claims (1)

[Claims] (1) For 100 parts by weight of unsaturated polyester resin,
Aluminum hydroxide 70-95 with an average particle size of 10 μm or less
1. A resin composition for press-molding artificial marble, comprising 150 to 350 parts by weight of a filler consisting of 30 to 5 weight % of aluminum hydroxide having an average particle size of 30 to 50 μm.