JP3257039B2 - Unsaturated polyester resin composition for artificial marble - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an unsaturated polyester resin composition for artificial marble, and more particularly to an unsaturated polyester resin composition for artificial marble capable of providing a molded article having no molding cracks and high transparency. About things.

[0002]

2. Description of the Related Art In recent years, artificial marble has been increasingly used in housing-related products such as bathtubs, kitchen counters, vanities, and tables, as the trend toward higher-grade products has increased. This is due to the fact that mining of natural marble is limited and the price is high. In addition, artificial marble based on unsaturated polyester resin can be formed into a complicated shape in a relatively short time and has various features. This is because it has advantages such as the ability to manufacture artificial marble. However, the unsaturated polyester resin shows a large shrinkage during curing, which causes cracks in the molded product, and various means for coping with this have been put to practical use.

In order to solve the problem of cracks, from the viewpoint of the material, the reactivity of the unsaturated polyester resin is reduced to suppress abrupt shrinkage, and the elongation of a molded article is increased by using a toughened unsaturated polyester resin. Or a method of blending a thermoplastic resin as a low-shrinking agent to reduce shrinkage. However, among these methods, the method of lowering the reactivity of the unsaturated polyester resin or increasing the toughness causes a decrease in boiling resistance or heat resistance, and causes a problem such as a great loss in commercial value. . In addition, the method of adding a low-shrinking agent has a fundamental problem that transparency is impaired.

On the other hand, a method for producing artificial marble using an unsaturated polyester resin includes (1) a normal temperature casting method, (2) a heating casting method, and (3) a heating method using a molding material such as BMC (bulk molding compound). There is a pressure molding method. The room-temperature casting method has the advantage of less occurrence of cracks during molding, but has the disadvantage that the molding time is long and the productivity is very poor. Although the productivity is improved in the hot casting method, cracks are frequently generated and the defective rate is increased. In addition, although the heat and pressure molding method is very excellent in mass productivity, the transparency of marble is greatly impaired because a large amount of filler is blended to prevent cracks and a low shrinkage agent is blended. There's a problem.

[0005] Among the measures for preventing cracks, the following is a specific example of a method of blending a low-shrinking agent. In JP-A-63-128057, a translucent artificial material free from cracks or distortion is formed by using a polystyrene-based polymer as a low-shrinking agent in combination with a specific unsaturated polyester resin and molding by heating and pressing. It is disclosed that a marble molding can be obtained. In addition, JP
JP-A-3-56555 discloses a method for producing a crack-free translucent artificial marble by heating and molding an unsaturated polyester resin molding material containing a three-dimensional styrene polymer as a low shrinkage agent. I have. However, when the polystyrene-based polymer used in the former method is used as a low-shrinking agent, the idea is that droplets of the polymer, such as styrene, expand due to heat generated during curing, which reduces curing shrinkage. Therefore, it is unavoidable that voids are left in the final cured product and considerable opacity occurs, and as a result, it is impossible to obtain an artificial marble molded article having the deep transparency of natural marble. Not at all. When the latter three-dimensional styrene polymer, which is a low-shrinkage agent, is used, voids are not left in the cured product, so that the transparency of the molded product is not significantly impaired, but the refractive index of the unsaturated polyester resin is reduced. Since the ratios are not similar, it is still difficult to obtain a molded article having high transparency. Further, since the shrinkage prevention effect is low, cracks may occur depending on the molding temperature during heat molding and the shape of the molded product. In addition, since any of the low-shrinkage agents has poor compatibility with the unsaturated polyester resin, the low-shrinking agent is raised on the surface during the curing process. in this way,
As for the low shrinkage agent, the ability to prevent shrinkage and the ability to maintain transparency are incompatible, and a low shrinkage agent having a high shrinkage prevention ability has a high degree of inhibiting transparency, and conversely, a low shrinkage that does not significantly impair transparency. The fact was that the agent had insufficient anti-shrinkage ability.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an artificial marble unsaturated polyester resin composition which can provide a highly transparent artificial marble molded article without generating cracks during heat molding. It is in.

[0007]

DISCLOSURE OF THE INVENTION The present invention has been proposed in view of the above, and is intended to crosslink a composition comprising an unsaturated polyester resin, an inorganic filler and a curing agent with styrene, methyl methacrylate and butyl acrylate. A specific amount of a three-dimensional copolymer having a specific crosslinking density and a specific refractive index based on a reactive monomer,
The present invention has been completed by finding the fact that the resin composition blended as a low-shrinkage agent can provide a highly transparent artificial marble molded product without generating cracks during heat molding. is there.

That is, according to the present invention, there is provided a three-dimensional copolymer comprising (a) an unsaturated polyester resin, (b) an inorganic filler, (c) a curing agent, and (d) a three-dimensional copolymer. The copolymer is a copolymer based on styrene, methyl methacrylate, butyl acrylate and a crosslinkable monomer.
The ratio of methyl acrylate and butyl acrylate is 1
0-85% by weight, 10-85% by weight, 5-50% by weight
(However, the total of the three components is 100% by weight)
And the crosslink density of the three-dimensional copolymer is 0.5 to 10%,
The refractive index is 1.50 to 1.57, and the copolymer is 3 to 30 parts by weight based on 100 parts by weight of the unsaturated polyester resin.
The present invention relates to an unsaturated polyester resin composition for artificial marble which is a part by weight.

The unsaturated polyester resin in the present invention is obtained by diluting an unsaturated polyester with an ethylenically unsaturated monomer copolymerizable with the unsaturated polyester. Any of the monomers can be used, but when the purpose is to produce a molded article that emphasizes boiling resistance, isophthalic acid or terephthalic acid, neopentyl glycol, bisphenol A alkylene oxide adduct or hydrogen Unsaturated polyester having bisphenol A
It is preferable to select an ethylenically unsaturated monomer having styrene as a main component.

As the inorganic filler, various glass powders, glass beads, glass fibers, glass fiber powders, aluminum hydroxide, barium sulfate and the like are preferable in consideration of the approximation to the refractive index of the unsaturated polyester resin. Considering the appropriateness, price, appearance of the molded article, boiling resistance, etc., borosilicate glass powder or aluminum hydroxide treated with a silane coupling agent having a refractive index of 1.50 to 1.57 is most preferable. . The amount of the inorganic filler is not particularly limited, but a practically preferable amount is 50 to 100 parts by weight of the unsaturated polyester resin.
To 300 parts by weight, more preferably 100 to 250 parts by weight. If the compounding amount is less than 50 parts by weight, cracks are easily formed during molding, and if it exceeds 300 parts by weight, the viscosity of the molding material is too high, workability is remarkably deteriorated, and the finally obtained molding The transparency of the product also deteriorates.

Examples of the curing agent include azobis compounds such as azobisisobutyronitrile, methyl ethyl ketone peroxide, bis (p-tert-butylcyclohexyl) peroxydicarbonate, tert-butyl peroxy-2-ethylhexanoate and tert. Organic peroxides such as hexylperoxy-2-ethylhexanoate, benzoyl peroxide, tert-butylperoxybenzoate, lauroyl peroxide, dicumyl peroxide, cumene hydroperoxide, and the like generally used for curing unsaturated polyester resins. And, if necessary, cobalt naphthenate,
Metal soaps such as cobalt octenoate, quaternary ammonium salts such as dimethylbenzylammonium chloride, β-diketones such as acetylacetone, and amines such as dimethylaniline, N-ethylmethtoluidine, triethanolamine as curing accelerators. Can be used together. The types and amounts of these curing agents and curing accelerators are appropriately selected depending on the desired molding temperature and molding time.

The three-dimensional copolymer in the present invention is a copolymer based on three components of styrene, methyl methacrylate and butyl acrylate, and a crosslinkable monomer. The ratio of styrene, methyl methacrylate, and butyl acrylate constituting the copolymer is 10 to 85% by weight, respectively.
It is preferable that the content is about 85% by weight and about 5 % by weight (however, the total of the three components is 100% by weight). Generally, the curing reaction of the unsaturated polyester resin involves a change in polarity in the system during the curing process. Therefore, unless it is a low-shrinking agent that can always maintain compatibility with the unsaturated polyester resin whose polarity changes with time, it will cause the surface to float or phase separation during the curing process. The former causes deterioration of the surface properties of the molded article, and the latter causes deterioration of the transparency of the molded article. The three components are a combination of limited monomers constituting a three-dimensional copolymer that can always maintain compatibility with the unsaturated polyester resin in the curing process,
Finally, it is possible to obtain a molded article having excellent surface properties and transparency.

When the unsaturated polyester resin composition of the present invention is used as a molding material such as BMC, by adding acrylic acid or methacrylic acid as a component to the three-dimensional copolymer, the molding material can be used. The stability of the three-dimensional copolymer in the inside can be improved, and the surface appearance of the artificial marble molded product can be further enhanced. The composition ratio of acrylic acid or methacrylic acid is from 1 to 5 based on the total weight of the components excluding the crosslinkable monomer of the three-dimensional copolymer, in view of the suitability of the thickening agent of the molding material such as BMC by the thickener described below. % By weight.

Examples of the crosslinkable monomer include divinylbenzene derivatives such as divinylbenzene and divinyltoluene, alkylene glycol di (meth) acrylate derivatives such as ethylene glycol dimethacrylate and ethylene glycol diacrylate, trimethylolpropane trimethacrylate, and methacryl. Allyl acid, diallyl phthalate, vinyl acrylate, vinyl crotonate and the like can include polyfunctional vinyl monomers having two or more polymerizable double bonds in one molecule, and one of these groups or Among them, two or more kinds are selected. Among them, allyl methacrylate or trimethylolpropane trimethacrylate is particularly suitable from the viewpoint of the performance of the three-dimensional copolymer as a low shrinkage agent.

The crosslink density of the three-dimensional copolymer is 0.5 to 10
%, And more preferably 1 to 5%. When the crosslink density is less than 0.5%, the solubility of the three-dimensional copolymer in the ethylenically unsaturated monomer, which is a component of the unsaturated polyester resin, increases, and the three-dimensional copolymer is blended. There is a tendency that the transparency of an artificial marble molded product produced from the unsaturated polyester resin composition obtained as described above is deteriorated. On the other hand, if it exceeds 10%, the three-dimensional copolymer is less likely to swell with the ethylenically unsaturated monomer, so that the ability of the three-dimensional copolymer to prevent shrinkage is reduced. When artificial marble is molded from the unsaturated polyester resin composition obtained by blending, cracks are likely to occur. The term "crosslink density" as used herein refers to the percentage by weight of the crosslinkable monomer constituting the three-dimensional copolymer with respect to the constituent components excluding the crosslinkable monomer.

The refractive index of the three-dimensional copolymer is 1.50.
1.57. As for the refractive index, for example,
Brand Wrap, edited by EH IMMERGAT, "Polymer Handbook" (Willie Interscience Publishing Co., Ltd.), Edition III, VI, pages 453-457 (1989)
Table 1 shows the refractive indexes of various polymers. The refractive index is a value calculated according to the copolymer composition ratio of a three-dimensional copolymer composed of styrene, methyl methacrylate, butyl acrylate, and a crosslinkable monomer. For example, polystyrene, polymethyl methacrylate, polybutyl acrylate, and polyallyl methacrylate have a refractive index at 20 ° C. of 1.
59, 1.49, 1.47 and 1.52, 2
The refractive index of a three-dimensional copolymer based on 5% by weight of styrene, 59% by weight of methyl methacrylate, 16% by weight of butyl acrylate and 1% by weight of allyl methacrylate is 1.51.
Becomes The refractive index of the three-dimensional copolymer is 1.50 to 1.57
When the ratio is out of the range, the transparency of the finally obtained molded product is deteriorated.

The amount of the three-dimensional copolymer is in the range of 3 to 30 parts by weight based on 100 parts by weight of the unsaturated polyester resin.
More preferably, it is in the range of 5 to 15 parts by weight. If the amount is less than 3 parts by weight, cracks are likely to occur when molding artificial marble from the unsaturated polyester resin composition obtained by blending the three-dimensional copolymer, and if it exceeds 30 parts by weight, The viscosity of the unsaturated polyester resin composition becomes too high, and the workability is remarkably poor, so that it is practically difficult to use.

In the three-dimensional copolymer of the present invention, benzoyl peroxide, lauroyl peroxide, tert-butylperoxy-2-ethylhexanoate, ditert-butyl peroxide, acetyl peroxide, tert-butylperoxybenzoate, Organic peroxides such as cumene hydroperoxide; azobis compounds such as azobisisobutyronitrile and azobisdimethylvaleronitrile; and inorganic peroxides such as ammonium persulfate, sodium persulfate, potassium persulfate and hydrogen peroxide. It can be produced by radical polymerization using a radical polymerization initiator. As the radical polymerization initiator, those having a 10-hour half-life temperature of 50 to 130 ° C. as exemplified above are preferable, and the amount of the radical polymerization initiator is 0.1 to the total weight of all the constituent components of the three-dimensional copolymer. ~ 5
% By weight.

Bulk polymerization, suspension polymerization,
Although any polymerization method such as an emulsion polymerization method can be mentioned,
Industrially, the suspension polymerization method is most preferable. At this time, as the suspending agent, partially saponified polyvinyl alcohol, sodium polyacrylate, sodium polymethacrylate, hydrophilic organic polymers such as carboxymethyl cellulose, tribasic calcium phosphate, barium sulfate, hardly soluble inorganic salts such as calcium carbonate and the like. Commonly used, but not limited to these. Also, when using difficult inorganic salts,
It is preferable to use an anionic surfactant in combination. Examples of the anionic surfactant include sodium alkyl benzene sulfonate, sodium α-olefin sulfonate, sodium alkyl sulfonate and the like. It is preferable that the types and amounts of the suspending agent and the anionic surfactant are appropriately selected depending on the particle size of the target final polymer.

In order to prepare the unsaturated polyester resin composition for artificial marble of the present invention by blending the three-dimensional copolymer, the three-dimensional copolymer is uniformly dispersed and swollen in the unsaturated polyester resin. It is necessary. For this reason, a three-dimensional copolymer in the form of fine powder may be directly blended with the unsaturated polyester resin and sufficiently mixed and dispersed, or the three-dimensional copolymer in the form of a granule or block may be previously mixed with an ethylenically unsaturated copolymer such as styrene. A gel which is sufficiently swollen with a saturated monomer may be blended with the unsaturated polyester resin. In addition, as a method for producing a fine powdery three-dimensional copolymer, a method of adjusting a polymerization method, a granular or bulk polymer obtained by ordinary suspension polymerization or bulk polymerization is finely pulverized by mechanical means. You can also do it.

In the case of producing a colored artificial marble molded product, an organic or inorganic dye or pigment is used to embody a marble-like pattern, whereby a product having a higher commercial value can be obtained. . Further, when the unsaturated polyester resin composition of the present invention is used as a molding material such as BMC, magnesium oxide, calcium oxide, magnesium hydroxide, an oxide of an alkaline earth metal such as calcium hydroxide or the like as a thickener. Hydroxide, zinc stearate, calcium stearate, stearic acid etc. as an internal mold release agent, inorganic fiber such as glass fiber, carbon fiber, etc., organic fiber such as aramid fiber, polyester fiber, vinylon fiber, metal fiber as reinforcing material Etc. can also be appropriately compounded.

The molding of the unsaturated polyester resin composition of the present invention is performed by introducing the unsaturated polyester resin composition into a preheated mold. A heat and pressure molding method in which a molding material such as BMC is introduced into a mold and then pressurized may be used. That is, the heat molding method includes heat and pressure molding. The molding temperature is preferably in the range of 60 to 150C. If the temperature is too low, it takes a long time to mold, leading to a decrease in productivity.
If it is too high, the molded article may burn and yellow, or the molded article may blister. The molding pressure is in the range of no pressure or 140 kg / cm ² or less, and the molding is carried out by sandwiching the unsaturated polyester resin composition between upper and lower molds. As the mold, a plywood mold, a resin mold, an electromold, and various metal molds can be used. The molding method may be any of a casting method, a compression molding method, an injection molding method, a transfer molding method, an injection molding method, an extrusion molding method, and the like.

[0023]

The three-dimensional copolymer, which is a constituent component of the unsaturated polyester resin composition of the present invention, is a copolymer in which a specific monomer component is three-dimensionally formed. Further, since it has a refractive index in a specific range close to the refractive index of the unsaturated polyester resin, it becomes possible to finally obtain a highly transparent artificial marble molded product from the unsaturated polyester resin composition. Further, by setting the cross-link density of the three-dimensional copolymer to a specific range, the degree of swelling by the ethylenically unsaturated monomer, which is a constituent component of the unsaturated polyester resin, can be adjusted. It is closely related to the ability to prevent shrinkage of the coalescence, and greatly contributes to preventing cracks during heat molding.

[0024]

As described above, the use of the unsaturated polyester resin composition containing the specific three-dimensional copolymer of the present invention makes it possible to prevent the shrinkage and the transparency, which were conventionally difficult to achieve. An artificial marble having high transparency can be obtained, having a holding ability and without generating cracks by heat molding.

[0025]

The present invention will be described in more detail with reference to Reference Examples, Examples and Comparative Examples. In these examples, parts and% represent parts by weight and% by weight, respectively, unless otherwise specified.

[Production Example of Three-Dimensional Copolymer of the Present Invention] Reference Example 1 150 parts of water and 1.5 parts of sodium dodecylbenzenesulfonate were placed in a glass reactor equipped with a thermometer, a nitrogen inlet tube, a stirrer, and a condenser. And 150 parts of a 10% aqueous solution of tribasic calcium phosphate. Next, 0.3 part of benzoyl peroxide (hereinafter abbreviated as BPO), 25 parts of styrene (hereinafter abbreviated as St), 59 parts of methyl methacrylate (hereinafter abbreviated as MMA), and butyl acrylate (hereinafter B)
A) and 16 parts of allyl methacrylate (hereinafter A)
Was dissolved in a mixture consisting of 1 part (abbreviated as MA) and charged to the reactor. While introducing nitrogen into the reactor, polymerization was carried out at 80 ° C. for 3 hours with stirring, and subsequently, polymerization was carried out at 90 ° C. for 30 minutes. After cooling to room temperature, the obtained polymer was washed with 5% hydrochloric acid (1000 g), subsequently with water, separated by filtration, and dried under vacuum to obtain 92 parts of a white fine powder polymer having an average particle diameter of 39 μm. Table 1 shows the results.

Reference Examples 2 to 5 A three-dimensional copolymer was produced in the same manner as in Reference Example 1 except that the amounts of St, MMA, BA and AMA were changed as shown in Table 1. A polymer was obtained. Table 1 shows the results. Reference Example 6 The same as Reference Example 1 except that in Example 1, methacrylic acid (hereinafter abbreviated as MAA) was used in addition to St, MMA, BA, and AMA, and the charged amount was changed as shown in Table 1. To produce a three-dimensional copolymer, and a white fine powdery polymer was obtained. Table 1 shows the results. Reference Example 7 In Reference Example 1, trimethylolpropane trimethacrylate (hereinafter abbreviated as TMPT) instead of AMA.
Was used to produce a three-dimensional copolymer in the same manner as in Reference Example 1, except that a white fine powdery polymer was obtained. Table 1 shows the results.

[Production Examples of Three-Dimensional Copolymer Deviating from the Claims of the Present Invention] Reference Examples 8 to 11 Reference Example 1 except that the amounts of St, MMA, BA and AMA were changed as shown in Table 1. In the same manner as in the above, a three-dimensional copolymer was produced to obtain a white fine powdery polymer. Table 1 shows the results. In Examples 8 and 9, the refractive index of the three-dimensional copolymer was different, and in Reference Examples 10 and 11, the composition ratio of the crosslinkable monomer, that is, the crosslink density, deviated from the scope of the present invention. .

[0029]

[Table 1]

Reference Example 12 [Preparation of Comparative Low Shrinkage Agent] (A) St Solution of PolySt PolySt (Dialex HF-77) manufactured by Mitsubishi Monsanto Kasei Co., Ltd. was adjusted to have a solid content of 30%. Was dissolved in St to obtain a comparative low-shrinking agent (A). (B) Three-dimensional St polymer According to the method described in Example 1 of JP-B-51-1276, an average particle diameter of 2 was obtained using 100 parts of St and 1 part of DVB.
An 8 μm three-dimensional St polymer was obtained and used as a comparative low-shrinking agent (B).

[Preparation of Unsaturated Polyester Resin Composition and Preparation of Artificial Marble Molded Article] Example 1 100 parts of unsaturated polyester resin (trade name: Yupica 6424, manufactured by Nippon Yupika Co., Ltd.), Reference Example 1 5 parts of bis (p-tert-butylcyclohexyl) peroxydicarbonate (manufactured by NOF CORPORATION, trade name: Parloyl TCP) 0.5 part, t
ert-hexyl peroxy-2-ethylhexanoate (trade name: Perhexyl O, manufactured by NOF Corporation)
Five parts and 200 parts of borosilicate glass powder (trade name: M-50S, manufactured by Nippon Fellow Co., Ltd.) were sufficiently stirred and mixed with a mixer to prepare an unsaturated polyester resin composition of the present invention.
After gently degassing the above composition with a vacuum pump,
00 × 100 × 5mm mold and 150 × 80 × 200
It was poured into a FRP mold having a bathtub shape of 10 mm in thickness and 10 mm in thickness, and was cured in a constant temperature bath at 80 ° C. to produce two types of artificial marble molded products. The molded product obtained from the mold is referred to as molded product A, and the molded product obtained from the FRP mold is referred to as molded product B. Table 2 shows the composition and the evaluation results obtained.

The measurement of the volume shrinkage of the cured product and the evaluation of the molded product were carried out as follows. Volume shrinkage of cured product The specific gravity of the composition is measured using a pycnometer. Then, the mixture was poured into a test tube having a volume of about 20 ml, the upper portion of the test tube was sealed, and the mixture was allowed to stand in an oil bath at 80 ° C. to advance curing. After the curing is completed, the cured product is taken out of the test tube, and the specific gravity of the cured product is measured using a solid specific gravity meter (Shimadzu Corporation S
GM-SH200 _-11) as measured by, determine the volume shrinkage of the cured product by the following equation. Volume shrinkage (%) = (1− (specific gravity of resin composition / specific gravity of cured product)) × 100 cracks The presence or absence of cracks generated in the two types of molded articles was visually determined. Total light transmittance The total light transmittance of the molded product A was measured using a direct-reading haze meter manufactured by Toyo Seiki Seisaku-Sho, Ltd. in accordance with JIS-K7105 (Test method for optical properties of plastics). Transparency The printed matter was placed under the molded article A, and it was determined whether or not the font was visible from above the molded article. A: The font can be confirmed and the font can be read. ：: The font can be confirmed, but the font cannot be read. ×: The font cannot be confirmed.

Examples 2 to 9 Using the three-dimensional copolymers obtained in Reference Examples 1 to 7, an artificial marble molded product was produced according to the composition shown in Table 2 according to Example 1. The molded product was evaluated according to Example 1, and the results are shown in Table 2.

[0034]

[Table 2]

Comparative Examples 1-4 Using the three-dimensional copolymers obtained in Reference Examples 8-11, molded articles of artificial marble were prepared according to the blending compositions shown in Table 3 in accordance with Example 1. Then, the molded product was evaluated according to Example 1, and the results are shown in Table 3.

[0036]

[Table 3]

COMPARATIVE EXAMPLES 5-7 In place of the three-dimensional copolymer, the comparative low-shrinkage agents (A) and (B) obtained in Reference Example 12 were used, and the blending compositions shown in Table 4 were used. An artificial marble molded product was prepared according to 1. Then, the molded article was evaluated according to Example 1,
The results are shown in Table 4.

Comparative Example 8 An artificial marble molded product was produced in the same manner as in Example 1 except that the three-dimensional copolymer was not used. The molded product was evaluated according to Example 1, and the results are shown in Table 4.

[0039]

[Table 4]

[Preparation of BMC molding material and preparation of artificial marble molding] Example 10 Unsaturated polyester resin (Dainippon Ink and Chemicals, Inc.)
100 parts of the three-dimensional copolymer obtained in Reference Example 6, 1 part of tert-butyl peroxybenzoate (manufactured by NOF CORPORATION, table name: Perbutyl Z) 200 parts of borosilicate glass powder (manufactured by Nippon Fellow Co., Ltd., trade name: M-50S) and 4 parts of zinc stearate (manufactured by Nippon Oil & Fats Co., Ltd., trade name: Zinc Ste) are kneaded with a Banbury type kneader for 15 minutes. And 1 part of magnesium oxide (trade name: Kyowa Mag # 40F, manufactured by Kyowa Chemical Industry Co., Ltd.), kneaded for 3 minutes, and aged at 40 ° C. for 24 hours to obtain a BMC molding material.
1000 × 300 heated to 140 ° C.
Placed in a mold of × 10mm, molding pressure 50kg / cm
^2. Heat-press molding was performed under a molding time of 9 minutes. As a result, an artificial marble molded article having high total light transmittance of 25%, high transparency and high surface gloss of 60% specular gloss of 90% and high surface gloss was obtained. The linear shrinkage of the obtained molded product was 0.09%, and no crack or warpage was observed in the molded product.

The evaluation of the molded product was performed as follows. Total light transmittance The total light transmittance of the molded article was measured using a direct-reading haze meter manufactured by Toyo Seiki Seisaku-Sho, Ltd. in accordance with JIS-K7105 (Test method for optical properties of plastics). 60-degree specular glossiness The molded product was measured for 60-degree specular glossiness using a gloss meter manufactured by Toyo Seiki Seisaku-Sho, Ltd. in accordance with JIS-K7105 (Test method for optical properties of plastics). Linear shrinkage The linear shrinkage of the molded product was measured by the following equation. Linear shrinkage (%) = ((longitudinal mold dimension−molded article dimension) / longitudinal mold dimension) × 100

Comparative Example 9 BMC molding was performed in the same manner as in Example 10 except that 30 parts of the comparative low-shrinkage agent (A) obtained in Reference Example 12 was used instead of the three-dimensional copolymer. A material was prepared, and an artificial marble molded product was produced using the molding material according to the conditions described in Example 10. When the molded product was evaluated according to Example 10, the total light transmittance was 8%.
And the transparency was low, and the result was that the 60 ° specular gloss was 45% and the surface gloss was low. The reason why the surface gloss of the molded product was poor was presumed to be that the stability of the low-shrinkage agent in the molding material was poor, and the molded product emerged on the surface during aging or curing. The linear shrinkage of the obtained molded product was 0.12%, and no cracks or warpage of the molded product were observed.

Comparative Example 10 BMC molding was performed in the same manner as in Example 10 except that the comparative low-shrinkage agent (B) obtained in Reference Example 12 was used in the same amount in place of the three-dimensional copolymer. A material was prepared, and an artificial marble molded product was produced using the molding material according to the conditions described in Example 10. When the molded product was evaluated according to Example 10, the total light transmittance was 12%.
And the transparency was low, and the result was that the 60 ° specular glossiness was 62% and the surface glossiness was slightly low. Although no crack was observed in the molded product, the obtained molded product had a linear shrinkage of 0.20%, which was a factor for dimensional stability. If the above Examples and Comparative Examples are compared, a three-dimensional copolymer having a specific crosslinking density and a specific refractive index based on the three monomer components and the crosslinking monomer specified in the present invention is an unsaturated polyester resin. When used as a low-shrinkage agent, it is apparent that an artificial marble molded article having high transparency can be obtained without cracks due to a small shrinkage rate during heat molding.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification code FI C08K 7/04 C08K 7/04 C08L 67/06 C08L 67/06 // (C08L 67/06 (C08L 67/06 25:08) 25:08)

Claims (2)

(57) [Claims] (1) An unsaturated polyester resin and (B)
Inorganic filler, (c) hardener, and (d) three-dimensional copolymer are essentially constituents. The three-dimensional copolymer is based on styrene, methyl methacrylate, butyl acrylate, and a crosslinkable monomer. Copolymer, styrene, methyl methacrylate
Butyl acrylate, 10-85 weight
%, 10 to 85% by weight, 5 to 50% by weight (however,
And the cross-link density of the three-dimensional copolymer is 0.5 to 10%, and the refractive index is 1.5.
0 to 1.57, and the copolymer is 3 to 30 parts by weight based on 100 parts by weight of the unsaturated polyester resin. 2. The three-dimensional copolymer is a copolymer based on styrene, methyl methacrylate, butyl acrylate, acrylic acid or methacrylic acid and a crosslinkable monomer.
The unsaturated polyester resin composition for artificial marble according to the above.