JPH07179616A - Artificial marble - Google Patents

Abstract

PURPOSE:To provide an artificial marble which is excellent in abrasion resistance and machinability and has a color tone with deep clarity and solidness. CONSTITUTION:This marble comprises 100 pts.wt. synthetic resin and 50-300 pts.wt. filler comprising aluminum hydroxide and a molten alumina powder provided the alumina powder is in an amt. of 0.2-5vol% of the marble.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an artificial marble used for a counter, a kitchen furniture top plate, a floor plate, etc., and relates to an artificial marble having excellent wear resistance and good machinability.

[0002]

2. Description of the Related Art Conventionally, artificial marble has used a molded product composed of a synthetic resin such as unsaturated polyester or methyl methacrylate resin as a matrix and a filler such as calcium carbonate, aluminum hydroxide or magnesium hydroxide. There is. Among these molded products, aluminum hydroxide is widely used as a filler because it has a transparent feel and gives a natural marble texture and is excellent in flame retardancy. However, when aluminum hydroxide is used, it has a fatal defect that it is easily scratched due to insufficient surface hardness. For example, when it is used for a counter, a kitchen furniture top plate, a floor plate, or the like, it has drawbacks such that a heavy object is placed on it or scratches or dents are likely to occur when moving the object. Therefore, as a means for increasing the surface hardness, a method of using a filler having a high hardness such as α-alumina, feldspar, silica, glass, or containing a large amount of the filler, a method of providing a gel coat layer having a high hardness, etc. are known. ing. However, when a large amount of filler with high hardness is used, the surface hardness becomes large and scratches are less likely to occur, but on the contrary, the machinability is markedly reduced, so it is necessary to use a special cutting tool such as a diamond tool. Therefore, it is not suitable for post-processing applications. In addition, when a large amount of filler is contained, the viscosity becomes high and the dispersibility of the filler deteriorates, resulting in a decrease in productivity, or the texture of the molded product such as transparency and gloss deteriorates. It has a drawback that it becomes brittle and its physical properties deteriorate. Further, when a gel coat layer having a high hardness is provided, the productivity is reduced due to complicated work steps, the cost is high, the molded product is warped, and the gel coat layer is peeled off. There is.

[0003]

SUMMARY OF THE INVENTION The object of the present invention is to solve the above-mentioned problems of the prior art and to improve wear resistance,
Moreover, it is an object of the present invention to provide an artificial marble which is excellent in machinability, has a deep color tone, and has a transparent feeling and a profound feeling.

[0004]

Means for Solving the Problems As a result of intensive studies for solving the above-mentioned problems, the present inventors have found that by containing a specific amount of a specific powder, it is excellent in wear resistance and cutting workability and has a deep color tone. The present invention has been accomplished by finding an artificial marble having a certain transparency and solidity. That is, in the present invention, the synthetic resin and the filler are in a weight ratio of 100: 50 to 30.
In the artificial marble consisting of 0, the filler is composed of aluminum hydroxide and fused alumina powder, and the fused alumina powder is contained in an amount of 0.2 to 5% by volume. As the filler, aluminum hydroxide, new Mohs hardness of 6 to 7, and refractive index of 1.50 to 1.
57 inorganic powder and fused alumina powder, and the inorganic powder is aluminum hydroxide and the total amount of the inorganic powder is 30
It is intended to provide an artificial marble having a weight% or less. Further, the present invention provides an artificial marble which is a methacrylic resin in which the synthetic resin is crosslinked. It also provides an artificial marble in which the synthetic resin is an unsaturated polyester resin.

Examples of the synthetic resin used in the present invention include methyl methacrylate polymers and copolymers of methyl methacrylate with (meth) acrylic acid, (meth) acrylic acid esters, styrenes, diallyl phthalate and divinylbenzene. The resin is not particularly limited as long as it is a known resin for artificial marble such as saturated polyester resin, vinyl ester resin, epoxy resin and urethane resin. Among them, the methacrylic resin and the unsaturated polyester resin cross-linked with polyfunctional (meth) acrylate are preferably used because those having high surface hardness and high heat resistance can be obtained.

Aluminum hydroxide used as a filler is white, chemically stable, has no discoloration, and has a refractive index of about 1.57 and a small difference from the refractive index of a resin used for artificial marble. Therefore, it gives an effect such as giving a sense of transparency. The aluminum hydroxide used in the present invention preferably has a central particle size of 3 to 30 μm, but is not particularly limited as long as it is used as a filler for artificial marble.

Α-alumina is characterized by a new Mohs hardness of 1
No. 2 is very hard, and when it is mixed with resin, the molded article is provided with abrasion resistance, but it has a drawback that the machinability is extremely deteriorated. The present invention, by containing a specific amount of specific α-alumina, without extremely deteriorating the machinability,
It was made based on the knowledge that abrasion resistance can be imparted. In α-alumina, α-alumina obtained by producing α-alumina by firing aluminum hydroxide obtained by the Bayer method and α-alumina obtained by firing are melted in an electric arc furnace and recrystallized,
There is a fused alumina powder produced by crushing this ingot. When these are included in artificial marble as a filler, the former has an effect on wear resistance, but
Its effect is smaller than that of fused alumina, and if it is used in a large amount, the machinability deteriorates depending on its content.
Further, if the content is large, the artificial marble is also whitened, which is not preferable. On the other hand, the fused alumina powder can remarkably improve the wear resistance with a small amount of addition, and since a small amount is sufficient, the machinability does not deteriorate so much. In the present invention, the content of the fused alumina powder in the artificial marble is preferably 0.2 to 5% by volume. If the content exceeds 5% by volume, the machinability deteriorates although the wear resistance does not further improve, which is not preferable. Further, the whitening of the artificial marble also becomes large, which is not preferable. 0.
If it is less than 2% by volume, the effect is not sufficiently exhibited. In particular, when the content is 0.3 to 1.5% by volume, the wear resistance is high and the machinability is good, which is more preferable. Furthermore, 0.3-1 volume% is especially preferable. The particle size of the fused alumina powder is not particularly limited, but if the central particle size is less than 50 μm, the whitening of the artificial marble becomes large and the transparency tends to be impaired. 300
If it exceeds μm, the smoothness of the surface of the artificial marble tends to be impaired.

Further, as a filler, it comprises aluminum hydroxide, an inorganic powder having a new Mohs hardness of 6 to 7 and a refractive index of 1.50 to 1.57 and a fused alumina powder, the inorganic powder being aluminum hydroxide and the inorganic powder. It is preferably 30% by weight or less of the total amount. Since these inorganic powders have a new Mohs hardness of 6 to 7, the surface hardness of the artificial marble can be made higher than that of aluminum hydroxide (new Mohs hardness of 3). Moreover, since the refractive index is 1.50 to 1.57, it is easier to obtain a transparent feeling, and therefore whitening due to the addition of the fused alumina powder can be prevented. Central particle size is 10
300 μm is preferable, and if it is less than 10 μm, abrasion resistance does not improve so much, and if it exceeds 300 μm, the smoothness of the surface deteriorates, which is not preferable. Further, if the content of these exceeds 30% by weight, the machinability is deteriorated, which is not preferable. Examples of these inorganic powders include glass, silica sand, feldspar, quartz and the like, with glass being particularly preferred.
In addition, it is more preferable to use a powder surface that has been subjected to a silane coupling treatment.

In the artificial marble according to the present invention, the weight ratio of the synthetic resin to the filler is 100: 50 to 300. When the amount of the filler added is less than 50 parts by weight, the artificial marble has a low specific gravity and lacks a feeling of weight, and the slurry has a low viscosity to deteriorate the moldability, and the molded product has a large shrinkage during polymerization and curing. This is not preferable because cracks may occur and manufacturing becomes difficult. On the other hand, if it exceeds 300 parts by weight, the physical properties such as strength will be deteriorated, or the viscosity of the slurry will be too high and the dispersion of the filler will be poor, so that a molded product having a uniform color tone cannot be obtained, which is not preferable. A more preferable weight ratio of the synthetic resin and the filler is 100: 100 to 200.

The artificial marble of the present invention may further contain fillers such as calcium carbonate and magnesium carbonate, if necessary.
Dyes, pigments, reinforcing agents, stabilizers, polymerization regulators, release agents, flame retardants, UV absorbers, antistatic agents, modifiers, colored particles and the like can be added. The artificial marble according to the present invention can be molded into various shapes of artificial marble by cast molding, injection molding, compression molding or the like.

[0011]

【Example】

Example 1 100 parts by weight of methyl methacrylate in which 4.5% by weight of polymethylmethacrylate resin (Acrycon ACP1 manufactured by Mitsubishi Rayon Co., Ltd.) was previously dissolved as a thickener was placed in a separable flask, and benzoyl peroxide was further used as a polymerization initiator. (NIPPER BO manufactured by NOF CORPORATION)
5 parts by weight of fused alumina powder (Showa Denko KK, White Morundum WA # 150, refractive index 1.76) (0.87% by volume in artificial marble) while adding 1 part by weight and stirring.
145 parts by weight of aluminum hydroxide powder (CW-308S, manufactured by Sumitomo Chemical Co., Ltd., refractive index: 1.57, central particle size: 8 μm), thoroughly mixed and defoamed, and then poured into a mold,
Then, it was left in a water bath at 60 ° C. for 3 hours and further at 80 ° C. for 4 hours to obtain an artificial marble. When this artificial marble was cut with a tip saw, the cutting workability was also good, and when it was polished and buffed with a refine polisher (manufactured by Refine Tech Co., Ltd.), a plate having gloss and a transparent feeling was obtained. When the abrasion resistance of this plate was measured by a Taber ablation tester (produced by Yasuda Seiki Seisakusho), it was a material with a small weight loss and scratch resistant. The physical properties are shown in Table 1.

Example 2 Example 1 except that the amount of fused alumina powder added in the filler was 22.5 parts by weight (4.0% by volume in the artificial marble) and aluminum hydroxide was 127.5 parts by weight. An artificial marble was obtained in the same manner as in. When this artificial marble is cut with a tip saw, it is hard, but there is no particular problem with the cutting workability. Also, refine polisher (made by Refine Tech Co., Ltd.)
After polishing and buffing with, a plate with gloss and transparency was obtained. When the abrasion resistance of this plate was measured by a Taber ablation tester (manufactured by Yasuda Seiki Seisaku-sho, Ltd.), the weight loss was extremely small and it was a material that was not easily scratched. The physical properties are shown in Table 1.

Example 3 As a polymerizable compound, methyl methacrylate in which 4.5% by weight of the polymethylmethacrylate resin used in Example 1 and 3% by weight of trimethylolpropane trimethacrylate were dissolved was used, and melted in the filler. 5 parts by weight of alumina powder (0.87% by volume in artificial marble), 143.5 parts by weight of aluminum hydroxide powder, glass bead powder (manufactured by Toshiba Ballotini, GB-731, refractive index 1.51) An artificial marble was obtained in the same manner as in Example 1 except that 1.5 parts by weight (center particle size: 30 μm) (about 1% by weight of the total amount of aluminum hydroxide powder and glass bead powder) was used. When this artificial marble was cut with a tip saw, the cutting workability was also good, and when it was polished and buffed with a refine polisher (manufactured by Refine Tech Co., Ltd.), a plate having a glossy and profound feeling was obtained.
The abrasion resistance of this plate was measured with a Taber ablation tester (manufactured by Yasuda Seiki Seisaku-sho, Ltd.). Table 1 for physical properties
Shown in.

[0014]

[Table 1]

Comparative Example 1 Aluminum hydroxide powder as a filler (CW-308S, manufactured by Sumitomo Chemical Co., Ltd., refractive index 1.57, central particle size 8 μ)
m) A molded product was obtained in the same manner as in Example 1 except that 150 parts by weight was added. When this molded product was cut with a tip saw and subjected to polishing buffing with a refine polisher (manufactured by Refine Tech Co., Ltd.), it was difficult to remove the marks of sandpaper due to polishing and it took a long time to finish the buffing. When the abrasion resistance of this plate was measured with a Taber ablation tester (manufactured by Yasuda Seiki Seisakusho Co., Ltd.), the weight loss was large.
The physical properties are shown in Table 2.

Comparative Example 2 As the alumina powder in the filler, an alumina powder obtained by a firing method (refractive index 1.76, average particle size 90 μm)
Was used in the same manner as in Example 1 except that 22.5 parts by weight (4.0% by volume in the artificial marble) and 127.5 parts by weight of aluminum hydroxide were used. When the abrasion resistance of this molded product was measured with a Taber ablation tester (manufactured by Yasuda Seiki Seisaku-sho, Ltd.), the weight loss was large. The physical properties are shown in Table 2.

Comparative Example 3 As in Example 1 except that the amount of fused alumina powder added in the filler was 37.5 parts by weight (6.7% by volume in artificial marble), and aluminum hydroxide was 112.5 parts by weight. A molded product was obtained in the same manner. When this molded product was cut with a tip saw, it was hard and had poor cutting workability. After polishing with a refine polisher (manufactured by Refine Tech), the surface was whitened and there was no transparency. The abrasion resistance of this molded product was measured with a Taber ablation tester (manufactured by Yasuda Seiki Seisakusho Co., Ltd.), and the weight loss was small. The physical properties are shown in Table 2.

[0018]

[Table 2]

[0019]

As described above, the artificial marble of the present invention is excellent in abrasion resistance and machinability, and has a deep and transparent tone and a profound feeling. Therefore, it is particularly useful as a counter, which requires post-processing such as cutting, and artificial marble such as kitchen furniture tops and floors.

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Claims (4)

[Claims] 1. The weight ratio of synthetic resin to filler is 100: 5.
An artificial marble comprising 0 to 300, wherein the filler comprises aluminum hydroxide and fused alumina powder, and the fused alumina powder is contained in the artificial marble in an amount of 0.2 to 5% by volume. 2. A filler comprising aluminum hydroxide, an inorganic powder having a new Mohs hardness of 6 to 7 and a refractive index of 1.50 to 1.57 and a fused alumina powder, wherein the inorganic powder is aluminum hydroxide and the inorganic powder. The artificial marble according to claim 1, which is 30% by weight or less based on the total amount of the powder. 3. The artificial marble according to claim 1, wherein the synthetic resin is a crosslinked methacrylic resin. 4. The artificial marble according to claim 1, wherein the synthetic resin is an unsaturated polyester resin.