JPH05163049A - Artificial marble or imitation granite having excellent transparency and its production - Google Patents

Abstract

PURPOSE:To provide a molded product of acrylic artificial marble or acrylic imitation granite having more transparent and deeper feeling and its producing method by bringing refractive index of a matrix resin close to refractive index of a filler to reduce irregular reflection. CONSTITUTION:(1) The objective artificial marble or imitation granite in which an inorganic filler is dispersed in a synthetic resin matrix and the synthetic resin matrix is composed of 60-90wt.% acrylic resin and 10-40wt.% AS resin and copolymerization wt. ratio of acrylonitrile and styrene in the AS resin is in the range of 2.1-9.0wt. based on 1wt. acrylonitrile. (2) The artificial marble or imitation granite is produced by a casting method, using a blend liquid obtained by blending a syrup-like polymerizable composition liquid consisting of 60-90wt.% acrylic acid ester based monomer and 10-40wt.% AS resin selected from AS resins in which copolymerization wt. ratio of acrylonitrile and styrene is in the range of 2.1-9.0 based on 1 acrylonitrile with an inorganic filler.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an artificial marble or imitation granite using a synthetic resin having an improved appearance as a base material and a method for producing the same.

[0002]

2. Description of the Related Art Marble and granite have hitherto been widely used as typical stone materials due to their decorative appearance. However, the cost required for polishing the surface is high, and plate-shaped products for construction use are brittle and easily cracked, so that a thickness of at least 20 mm or more is required to maintain strength. Therefore, it becomes expensive and very heavy due to the high specific gravity, and special attention is required for transportation, mounting on a wall, and the like. For this reason, the use is greatly restricted, and it is difficult to put a product having a large area exceeding 1 m ² into practical use.

Therefore, conventionally, there has been a demand for a material that does not require surface polishing, is lightweight, has sufficient strength, is easy to handle and attach, and has a beautiful marble or granite appearance.

As a product using a synthetic resin imitating natural stone as a base material, a marble-like molded product is manufactured by a casting method and put into practical use as an artificial marble counter or the like.

As the synthetic resin base material, an acrylic resin having a practically sufficient strength and having excellent luster and excellent performance such as good weather resistance is widely used.

[0006] However, it has not been realized to manufacture a molded product having a depth and transparency similar to the polished surface of natural marble by a casting method using an acrylic resin as a base material.

Further, it has a depth close to the polished surface of natural granite, and large particles are scattered on average not only in the surface direction but also in the thickness direction. It has not been realized that an acrylic resin as a base material is also manufactured by a casting method.

[0008]

The reason why it is not possible to artificially obtain the speckled pattern rich in the deep transparency of natural marble and the deep three-dimensional effect of natural granite is the base acrylic resin. refractive index of (n indicates a _D, hereinafter) is 1.49
On the other hand, the refractive index of aluminum hydroxide, which is widely used as a filler from the viewpoint of being able to obtain the texture of a natural stone material, being sufficiently stable against heat and chemicals in practical use, and from the viewpoint of cost, The refractive index of these inorganic fillers is 1.57, and that of quartz is 1.54, which is higher than that of the base acrylic resin.As a result, these artificial fillers are dispersed in the acrylic resin base material. This is because irregular reflection of light occurs at the interface between the material resin and the filler particles, and the product becomes white turbid, resulting in a product having an inferior transparent appearance and a poor sense of depth.

The present invention has been made in view of the above circumstances. The purpose is to bring the refractive index of the base material resin close to the refractive index of the filler to reduce the irregular reflection, and to provide a more transparent feeling.
It is to provide a molded product of acrylic artificial marble or acrylic imitation granite with a sense of depth.

As a method for increasing the refractive index of the acrylic resin base material, it is generally known to copolymerize a styrene-based monomer during casting, and the resin thus obtained is a styrene-based monomer. The refractive index increases as the copolymerization ratio of is increased. However, when using styrene,
As the styrene content increases, the curing time becomes longer, which leads to a decrease in the line speed in industrial production, which is a problem, and the molded product thus obtained has a lower weather resistance than the original acrylic resin. , Causing inconvenience such as yellowing during use of the product.

Further, the use of α-methylstyrene leads to a longer curing time, and in the case of bromostyrene, the weather resistance is further deteriorated, and it is used only for a special purpose. This is a problem because it is industrially difficult.

Further, when a typical polystyrene (refractive index: 1.59), which is a transparent general-purpose resin having a large refractive index, is dissolved in an acrylic acid ester-based monomer and polymerized and cured, only a cloudy and opaque resin is obtained. This is well known and is not suitable as a base material resin for transparent artificial marble.

[0013]

In the artificial marble or imitation granite according to the present invention, an inorganic filler is dispersed in a synthetic resin base material, and the synthetic resin base material is an acrylic resin 60.
.About.90% by weight and 10 to 40% by weight of AS resin, and the copolymerization ratio of acrylonitrile and styrene of the AS resin is in the range of 2.1 to 9.0 with respect to 1 acrylonitrile by weight.

Another method of producing an artificial marble according to the present invention is a mixed liquid in which an inorganic filler is mixed with a syrup-like polymerizable composition liquid obtained by dissolving an AS resin in an acrylic ester monomer. Is a method for producing an artificial marble by a casting method, wherein the syrup-like polymerizable composition liquid is 60 to 90% by weight of an acrylic acid ester monomer, and the copolymerization ratio of acrylonitrile and styrene is 1 to acrylonitrile by weight. 2.
It is characterized by dissolving 10 to 40% by weight of AS resin selected from the range of 1 to 9.0.

Further, in the present invention, a patterned artificial marble having an appearance in which spotted patterns and the like are scattered is used by using a mixed solution in which a part of the inorganic filler is replaced with white, black, or colored chromatic particles. You can also do it.

That is, when an AS resin having a specific composition is dissolved and blended in an acrylic acid ester type monomer and the syrup-like polymerizable composition liquid is cured to form a base material resin, the base material resin is transparent. And has a high refractive index as compared with one in which the AS resin is not dissolved and blended in the acrylic ester-based monomer, and by approximating the refractive index of the inorganic filler,
When the artificial marble filled with the inorganic filler and the patterned artificial marble described above are used, the transparency of the molded product is remarkably improved.

The acrylic ester type monomer of the present invention is
Unsaturated monomers containing methyl methacrylate as a main component and copolymerizable therewith, for example, monomers such as methyl acrylate, ethyl methacrylate, 2-ethylhexyl methacrylate, vinyl acetate, etc. It is possible to add a small amount of styrene-based monomer and cross-linking agent such as divinylbenzene, ethylene glycol dimethacrylate, diallyl phthalate, stabilizers such as UV absorbers, and coloring agents, etc. . To improve workability when manufacturing artificial marble by the casting method,
It is generally practiced to dissolve an acrylic resin in the acrylic acid ester-based monomer to thicken it.

The AS resin used in the present invention is also intended for this thickening action. The AS resin contains acrylonitrile and styrene as main components, and the acrylonitrile 1 is used in a weight ratio.
On the other hand, styrene is selected from the range of 2.1 to 9.0, and when it is out of this range, it is dissolved in the acrylic acid ester-based monomer, and the syrup-like polymerizable composition liquid is cured to form a base material resin. In addition, the base material resin becomes cloudy, and the intended purpose cannot be achieved.

The proportion of the AS resin to be dissolved is preferably 10 to 40% by weight, based on the acrylic acid ester-based monomer.
If it is less than 10% by weight, the effect of improving the base material resin is not sufficient, the transparency is unsatisfactory, and the product is not uniform due to the sedimentation of the inorganic filler during the production by the casting method.

If it exceeds 40 parts, the viscosity of the syrup becomes high and it becomes difficult to mix a predetermined amount of the filler, and product defects such as insufficient filling due to low fluidity during casting work occur. There is a problem because it arises.

In the present invention, the base material resin is 25 to 70% by weight.
The range is. If it is less than 25% by weight, it is difficult to obtain a molded article having good appearance and physical properties such as impact strength. Further, in the production, the ratio of the amount of the polymerizable composition liquid becomes low, the viscosity of the liquid mixture containing the filler and the like becomes high, and the molding by the casting method becomes difficult. When it exceeds 70% by weight, the precipitation of finely divided inorganic filler particles becomes remarkable during the production, and a molded product having an appearance similar to marble or granite and excellent physical properties cannot be obtained. The base resin or the polymerizable composition liquid is preferably 30 to 40% by weight.

Further, as the inorganic filler used,
Typical examples are aluminum hydroxide and quartz, which can impart a natural marble or natural granite-like texture to the base material resin, but other examples include the use of cristobalite, calcium carbonate, magnesium hydroxide, calcium silicate, etc., either alone or mixed. It is possible to use it.

The average particle size of these fillers is 2 to 70 μm, more preferably 5 to 50 μm.

The proportion of large-sized particles to be mixed in order to obtain artificial marble or imitation granite having a speckled pattern is 1 to 40% by weight of the total amount of the mixed solution. If it is less than 1% by weight, the pattern feeling becomes poor, and if it exceeds 40% by weight, the pattern feeling becomes rich and it becomes difficult to obtain a molded article having a three-dimensional appearance. It is more preferred to use the opaque particles in a proportion of 5 to 25% by weight. Further, the particle size of the particles is 0.1 mm or more, and if it is less than 0.1 mm, the presence thereof is poor, and it is preferably 3 mm or less in order to form an average spot-like pattern. The color tone of large particles has a great influence on the appearance of the product. To obtain a general granite tone, a mixture of white and black is used, and by changing the ratio, so-called white or black stains can be obtained. It is also possible to select and mix colored chromatic particles to make them rare in nature such as reddish stains. Further, it is possible to freely set a color tone other than this.

Suitable examples of the large-sized inorganic particles include crushed particles of natural minerals such as basalt, iron ore, granite and graphite, or crushed particles of artificial inorganic substances such as bricks and pottery. It is preferably opaque with a specific gravity of 1.7 or more. Specific examples are as follows.

White particles: pottery, shells, anhydrite, black particles: graphite, anthracite, black slate (Nachi black stone), black marble (Mino black stone), biotite, colored chromatic particles: bricks, colored pottery, colored tiles, As the large-sized organic particles, for example, crushed particles of opaque or translucent products of various plastics are easy to select in terms of providing a decorative effect, and industrially available and simple.

It is preferable that these crushed plastic particles are insoluble or not easily dissolved in the acrylic acid ester-based monomer when it is used as a compounding liquid. For example, polyethylene,
One or a mixture of polyester, crosslinked polymethylmethacrylate, etc. may be mentioned.

Other large-sized organic particles include wood chips, short fibers and the like. Of course, large-sized inorganic and organic particles may be mixed.

In order to mold by the casting method, a polymerization initiator is added to a compounded liquid in which an inorganic filler and, if necessary, large-sized particles are mixed and dispersed in a syrup-like polymerizable composition liquid,
After defoaming treatment under reduced pressure, it is poured into a prepared mold to be polymerized and cured.

As the polymerization initiator, radical polymerization initiation of peroxides such as benzoyl peroxide, lauroyl peroxide, dimyristyl peroxydicarbonate, azo compounds such as azobisisobutyronitrile, azobisdimethylvaleronitrile, etc. Agents are commonly used.

It is also common practice to add a dispersant to the composition liquid in order to enhance the dispersibility of the filler.

[0032]

The present invention is constructed as described above. This artificial marble or imitation granite contains an inorganic filler as a main material in a base material resin obtained from a syrup obtained by dissolving an AS resin having a specific composition in an acrylate monomer. Since the refractive indices of both are similar, the present invention provides an acrylic artificial marble or imitation granite having an unprecedentedly excellent transparency.

Further, the present invention also provides an artificial marble having a speckled pattern rich in three-dimensional effect, in which large-sized particles are dispersed and contained as needed, using the artificial marble as a base material.

At the same time, it is possible to produce artificial marble or imitation granite which has practical heat resistance and strength suitable for various uses, does not require surface polishing, is lightweight, and is excellent in handling.

[0035]

EXAMPLES The present invention will be described in detail below with reference to examples. In addition, all "parts" in an Example show a "weight part."

Example 1 Methyl methacrylate (85 parts) was mixed with AS resin (acrylonitrile (hereinafter AN) and styrene (hereinafter ST)) in a weight ratio of 1: 3.
15 parts of the copolymer of 1.57) and a refractive index of 1.57) are added and dissolved by stirring at 60 ° C, then cooled to room temperature, and 1 part of ethylene glycol dimethacrylate is added to obtain a syrup-like polymerizable composition liquid.

(Composition of Raw Material Mixing Liquid) Polymerizable composition liquid 33 parts Aluminum hydroxide powder (average particle size 9 μm) 67 parts Dimylisterperoxydicarbonate 0.3 parts The above composition was stirred and mixed at room temperature for 20 minutes to mix the raw materials. A liquid was obtained, the viscosity of which was 10 poise (by a B-type rotational viscometer).

The mixed solution was defoamed under reduced pressure for 10 minutes, and then two alumite-treated aluminum plates were cut to 12 mmφ.
Crushed with a soft vinyl chloride resin gasket of No. 1 and poured into a mold fixed with a vise, and immersed in warm water at 65 ° C for 2 hours to polymerize and cure, then left in an air bath at 120 ° C for 5 hours. And completely cure. The plate-shaped molded product obtained by opening the mold had a marble appearance with a transparent feeling.

Example 2 The copolymerization weight ratio of AS resin is AN: ST = 1: 7, and the refractive index is
A plate-shaped molded body is obtained in the same manner as in Example 1 except that 1.58 is used. The molded body had a transparent, marble-like appearance.

Example 3 (Composition of raw material compounding liquid) Polymerizable composition liquid 30 parts Quartz powder (average particle size 25 μm) 35 parts Aluminum hydroxide powder (average particle size 15 μm) 15 parts Slate (Nachi Kuroishi) crushed particles (particle size 0.2 ~ 1.5 mm) 5 parts White porcelain ground particles (particle size 0.3-2.5 mm) 15 parts Dimylisterperoxydicarbonate 0.3 parts In the same manner as in Example 1, a compounded solution having the above composition is prepared to obtain a plate-shaped molded body. This molded product had a so-called deep and beautiful patterned marble tone in which the speckled pattern was scattered evenly in appearance, and black and white spots near the surface were transparent.

The average particle size in the above examples is the particle size distribution measuring device (SA-CP2) manufactured by Shimadzu Corporation.
It is a value measured by using
It excludes small particles and large particles outside the recording range.

Comparative Example 1 Acrylic resin (registered trademark Delpet 80N, manufactured by Asahi Kasei Co., Ltd.) containing polymethylmethacrylate as a main component was used as a dissolving synthetic resin when a polymerizable composition liquid was prepared. A plate-shaped molded body is prepared in the same manner as in Example 1.

Compared with the molded product obtained in Example 1, this molded product had a cloudy appearance and was less transparent.

Comparative Example 2 Example 1 except that 51 parts of methyl methacrylate and 34 parts of styrene and 15 parts of MS resin (registered trademark Estyrene MS600, a copolymer of methyl methacrylate and styrene, manufactured by Nippon Steel Chemical Co., Ltd.) were used. I tried to obtain a plate-shaped molded body in the same manner as in, but the contents were soft even after being immersed in warm water at 65 ° C for 4 hours,
A good plate-shaped molded product could not be obtained.

Comparative Example 3 A syrup-like polymerizable composition liquid was obtained in the same manner as in Example 1 by using various AS resins having different copolymerization ratios of AN and ST, and the polymerizable composition liquid was kept under reduced pressure for 10 minutes. After defoaming, inject into a test tube with an inner diameter of 12 mm, seal it, and soak it in warm water at 50 ° C for 16 hours to polymerize and cure it, then leave it in an air bath at 120 ° C for 5 hours to completely cure it. , The appearance was evaluated.

The results are summarized in Table 1.

[0047]

[Table 1]

[0048]

EFFECTS OF THE INVENTION The present invention is as described above. This artificial marble or imitation granite has (1) a transparent appearance that closely resembles the polished surface of natural marble, and (2) natural stone if necessary. It is possible to add a spotted pattern with a depth that is similar to the polished surface of granite, and is rich in three-dimensionality. (3) Light weight and excellent handling such as transportation and installation. ) It has practically sufficient strength.

Therefore, it can be used in a wide range of applications in place of natural marble or granite.

Further, according to this method for producing artificial marble, when the raw material-blended liquid is cured and molded by the casting method, there is no delay in the curing time, and it can be produced by a stable process.

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Claims (2)

[Claims] 1. An artificial marble in which an inorganic filler is dispersed in a synthetic resin base material, wherein the synthetic resin base material comprises 60 to 90% by weight of an acrylic resin and 10 to 40% by weight of an AS resin, An artificial marble or imitation granite in which the copolymerization ratio of acrylonitrile and styrene of the AS resin is in the range of 2.1 to 9.0 based on 1 of acrylonitrile. 2. A resin containing 60 to 90% by weight of an acrylic acid ester-based monomer and 10 to 40% by weight of an AS resin selected from the range of 2.1 to 9.0 with respect to 1 acrylonitrile by a copolymerization ratio of acrylonitrile and styrene. %, A method for producing artificial marble or imitation granite by a casting method using a compounding liquid in which an inorganic filler is mixed with a syrup-like polymerizable composition liquid consisting of 10% by weight.