JPH03220262A - Unsaturated polyester resin composition for artificial marble - Google Patents

Abstract

PURPOSE:To prepare the title compsn. which enables a thermal press molding of an artificial marble having a transparency, surface flatness, and gloss comparable to those of an artificial marble made by casting by using an unsatd. polyester resin having a specific compsn. and bringing the refractive indices of the cured polyester resin and a filler each into a specified range. CONSTITUTION:The title compsn. is prepd. by compounding: 100 pts.wt. unsatd. polyester resin which contains a dibasic acid component contg. 20-50mol% terephthalic acid and gives a cured resin having a refractive index of 1.545-1.575; with 300-550 pts.wt. at least one inorg. filler having a refractive index of 1.545-1.575 and selected from the group consisting of aluminum hydroxide, glass powder, etc. The compsn., when thermally press molded, gives a marblelike molded article having a transparency, surface flatness, and gloss comparable to those of an artificial marble made by casting and showing a texture with depth.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to an unsaturated polyester resin composition, and more specifically to an artificial marble that is transparent and that enables mass production of artificial marble by heat and pressure molding. The present invention relates to an unsaturated polyester resin composition for use.

(Prior Art) Artificial marble made of resin, which is characterized by a unique deep color tone, can be molded into complex shapes and has recently been used for various purposes. Resin-made artificial marble is roughly divided into two types: those based on acrylic resin and those based on unsaturated polyester resin. In particular, products based on unsaturated polyester resins can be made into complex shapes and have excellent heat resistance, and demand is growing rapidly.

(Problem to be solved by the invention) However, for artificial marble based on unsaturated polyester resin, a gel coat layer is formed on one surface, the main body is molded by a casting method, and the back side is reinforced with a colored layer and FRP. A unique color tone and depth are achieved through a complex molding method. Therefore, productivity is extremely low and it is almost handmade. In order to increase productivity, pressure and heat molding methods using molding materials that integrate a casting layer and a reinforcing layer, as typified by press molding of BMC and SMC, are being considered.1) Glass fiber and inorganic filler 2) addition of a low-shrinkage agent used to ensure surface smoothness and prevent cracks in uneven thickness areas, etc., can significantly reduce the transparency of the molded product. One of the reasons for the decrease in transparency is the difference between the refractive index of the cured unsaturated polyester resin and the refractive index of the filler, and as a filler, hydroxide has a refractive index closer to that of the cured unsaturated polyester resin than normal calcium carbonate. Aluminum, vitreous frit or glass powder is used,
Transparency is much lower than that of the casting method. Furthermore, consideration has been given to using vinyl ester resins whose refractive index is close to that of the filler, but this can avoid coloring of the resin system, reduction in gloss, deterioration in moldability, and accompanying deterioration in molded appearance and leveling. It has not reached a level where it can be put to practical use.

Therefore, an object of the present invention is not only to use a filler whose refractive index is close to that of a cured unsaturated polyester resin, but also to use an unsaturated polyester resin with a specific composition to improve the refractive index of the cured resin and the filler. The object of the present invention is to provide an unsaturated polyester resin composition which, by combining the ingredients within a specific range, enables heat-pressure molding of artificial marble having transparency, surface smoothness, and gloss comparable to that of the casting method.

(Means for Solving the Problems) In order to solve the drawbacks of the prior art as described above, the present inventors have conducted extensive research and found that 1) an unsaturated polyester resin and a filler having a refractive index in a specific range; By the combination of the following, an unsaturated polyester resin composition is obtained that enables heating and pressure molding of artificial marble with transparency, back surface smoothness, and gloss comparable to that of the casting method. 2) A part of the dibasic acid component is A cured resin using unsaturated polyester made of terephthalic acid has a high refractive index almost equivalent to that of vinyl ester resin, and is extremely light in color. 3) A filler that was previously thought to be a factor in reducing transparency. The present invention was completed based on the discovery of the novel fact that transparency and other textures improve when the amount added is above a specific amount.

That is, in the present invention, 20 to 50 mol% of the dibasic acid component
is made of terephthalic acid, and the refractive index of the cured resin is 1.
545-1.575 unsaturated polyester resin 10
0 parts by weight of at least one inorganic filler selected from aluminum hydroxide, glass powder, etc. and having a refractive index of 1.545 to 1.575. This invention relates to an unsaturated polyester resin composition for marble.

(Function) The unsaturated polyester resin used in the present invention is obtained by dissolving an unsaturated polyester obtained by condensing an unsaturated dibasic acid, a saturated dibasic acid, and a polyhydric alcohol in a crosslinkable monomer. However, it is characterized in that 20 to 50 mol% of the dibasic acid component of the unsaturated polyester consists of terephthalic acid. When the proportion of terephthalic acid in the dibasic acid component of the unsaturated polyester is 20 mol% or less, the refractive index of the cured unsaturated polyester resin is 1.54.
If the proportion of terephthalic acid is less than 50, the effect of the present invention cannot be obtained, and if the proportion of terephthalic acid is more than 50 mol %, defects in appearance such as a decrease in gloss due to a decrease in reactivity regulated by the amount of unsaturated dibasic acid occur.

Unsaturated dibasic acids used to obtain unsaturated polyesters include fumaric acid, maleic acid, maleic anhydride, etc.; saturated dibasic acids include terephthalic acid, phthalic acid, phthalic anhydride, isophthalic acid, etc. Examples include acids such as succinic acid, adipic acid, and sebacic acid.

Ethylene glycol is the polyhydric alcohol used to obtain unsaturated polyester resins.

Examples include diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, neopentyl glycol, bisphenol A, hydrogenated bisphenol A, and the like.

Crosslinkable monomers used to obtain unsaturated polyester resins include styrene, α-methylstyrene, divinylbenzene, diallyl phthalate, acrylic esters, methacrylic esters, trimethylolpropane triacrylate, and trimethylolpropane. Examples include trimethacrylate, pentaerythritol triacrylate, pentaerythritol trimethacrylate, and the like. The crosslinkable monomers used in the present invention are not limited to one type, and two or more types can be used in combination.

The proportion of the crosslinkable monomer in the unsaturated polyester resin is 25 to 55% by weight.

The unsaturated polyester resin is not limited to one type, but by using two or more types of unsaturated polyester resin in combination, the amount of the dibasic acid component is 20 to 20% based on the total amount of unsaturated polyester.
Terephthalic acid may account for 50 mol%, and the refractive index of the cured resin may be in the range of 1.545 to 1.575.

Examples of the filler having a refractive index of 1.545 to 1.575 used in the present invention include aluminum hydroxide, vitreous frit, and glass powder. The amount added is 300 to 5 parts by weight per 100 parts by weight of the unsaturated polyester resin.
If the amount added is less than 300 parts by weight, transparency and other textures comparable to those obtained by the casting method cannot be obtained;
If it exceeds 50 parts by weight, workability is lowered due to crosslinking of glass fibers, resulting in a decrease in transparency and other textures. Calcium carbonate, clay, and other commonly used fillers may be used in combination as long as they do not impair the effects of the present invention.

The glass fibers used in the present invention are generally used in unsaturated polyester resin compositions, and there are no particular restrictions on the fiber length, fiber diameter, surface treatment, etc. The proportion in the unsaturated polyester resin composition varies depending on the use, but is 3 to 20%. In addition to glass fibers, inorganic fibers such as asbestos and alumina whiskers, vinylon fibers, polyester fibers, acrylic fibers, and other organic fibers may be used in combination as fibrous reinforcing materials.

In addition to the above, the unsaturated polyester resin composition of the present invention may be made of a known/commonly used thermoplastic resin that has low shrinkage as long as it does not impair the effects of the present invention, and may be used as a low shrinkage agent. Examples of thermoplastic resins include polystyrene, polymethyl methacrylate, and the like. Furthermore, additives commonly used in unsaturated polyester resin compositions, such as internal mold release agents such as zinc stearate, curing catalysts such as benzoyl peroxide, thickeners, and colorants, are used within the range that does not impair the effects of the present invention. You may.

Hereinafter, the present invention will be specifically explained with reference to Examples.

(Example) BMC prepared by kneading various formulations shown in Table 1 in a Banbury type kneader was prepared at a molding temperature of 140°C and a molding pressure of 1.
00 kg/d, molding time 5 minutes, thickness 5m
A flat plate was obtained. As a result, molded articles with good surface smoothness and surface gloss and deep transparency were obtained in all Examples.

(Comparative example) BMCs made of various formulations shown in Table 2 were prepared at a molding temperature of 140°C, a molding pressure of 100 kg/a#, and a molding time of 5.
Molding was carried out in minutes to obtain a flat plate with a thickness of 5++a. As a result, a molded article having the texture and transparency seen in the Examples could not be obtained.

(Effects of the Invention) By heating and press-molding the unsaturated polyester resin composition of the present invention, an astronomical stone-like molded article having a deep texture comparable to that obtained by the casting method can be obtained.

Claims (1)

[Claims] 20 to 50 mol% of the dibasic acid component consists of terephthalic acid, and the refractive index of the cured resin is 1.545 to 1.575.
The refractive index selected from aluminum hydroxide, glass powder, etc. is 1 for 100 parts by weight of unsaturated polyester resin.
．． An unsaturated polyester resin composition for use in artificial marble, comprising 300 to 550 parts by weight of at least one inorganic filler having a molecular weight of 545 to 1.575.