JP2000327389A - Composition for artificial marble and artificial marble - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide artificial marble easy to be released from a mold and capable of being produced in a good productivity while retaining strength, heat resistance, weather resistance and hot water resistance, and also to provide an artificial marble composition therefor. SOLUTION: This artificial marble composition contains (A) 100 pts.wt. acrylic component comprising methyl methacrylate and methyl methacrylate units as main ingredients, (B) 10-400 pts.wt. treated inorganic filler having an average particle diameter of 5-30 μm, (C) 0.001-1 pt.wt. radical polymerization initiator in a thermal polymerization-initiating system and (D) 0.04-10 pts.wt. releasing agent. This artificial marble is obtained by curing the composition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an artificial marble having excellent strength, heat resistance, weather resistance and hot water resistance, easy release from a mold during production, and good productivity.

[0002]

2. Description of the Related Art Acrylic resin-based artificial marble is a slurry obtained by mixing a large amount of an inorganic filler, particles for expressing a stone-like pattern, various additives, a curing initiator, a pigment, etc., with an acrylic component. A raw material mixture in the form of a plate is produced, injected into a mold or the like, cured by a curing device to produce a plate-like product, and then subjected to edge trimming and surface polishing to obtain a final product. Such an acrylic resin-based artificial marble is made of a nonporous material having a uniform surface and inside, so that it is solid, and can be easily cut, polished, bent by heat, joined by an adhesive, and the like. Demand for building materials such as sink top plates, various counters, washstands, and wall materials is increasing.

[0003] Usually, such an acrylic resin-based artificial marble is produced by two types of production methods, a batch type cell casting method and a continuous casting method. The cell casting method disclosed in JP-A-52-36155 and JP-A-53-112990 discloses a method in which a resin gasket is put in two metal plates or glass plates and a mold is pressed by a clamp. After the raw material mixture is poured into a hot water tank or an air circulation oven, the raw material mixture is cured, and then the mold is disassembled to obtain a cured product.

On the other hand, a continuous casting method of an acrylic plate disclosed in JP-B-47-34815, JP-B-49-35818, and JP-B-49-36944 has been used for the production of artificial marble. There is a manufacturing method. This method comprises a pair of endless belts provided at the top and bottom, which run at the same direction and at the same speed, a device for continuously supplying a resin gasket between both sides in the width direction of the belt, a heating and cooling device, and the like. In this method, a raw material mixture is continuously injected into a space formed by a belt and a gasket using a curing device, and is continuously polymerized according to the movement of the belt to obtain a plate-like product.

[0005] Also, US Patent No. 3,570,05
No. 6 discloses a plate-shaped product obtained by injecting a polymerization raw material for an acrylic resin plate into a continuous curing device comprising one endless belt and an auxiliary device, and continuously curing the same according to the movement of the endless belt. Are disclosed. This publication also discloses a method in which a film is attached to the surface of an endless belt, a polymerization material is poured, and the polymerization material is further covered with another film.

When these methods are used for producing artificial marble containing an inorganic filler, a cured polymer adheres to a metal plate constituting a mold or a belt, and the releasability of the artificial marble, which is a cured product, is obtained. Had a problem. This is because when the inorganic filler and the inorganic filler contained in the raw material mixture are surface-treated, the adhesion between the surface-treating agent and the metal is high. If the content of the inorganic filler is the same, the particle size of the inorganic filler is smaller and its surface area is larger, and if the inorganic filler is surface-treated, the larger the amount of the surface treatment agent used, the more the mold release. Worse.

[0007] In order to prevent poor mold release, a method of pasting a mold release film on a mold or belt for producing artificial marble in advance, or injecting a raw material after providing a coating and polymerizing and curing, has been performed. There was a problem that the process became complicated and the manufacturing cost increased.

[0008]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and its object is to maintain strength, heat resistance, weather resistance and hot water resistance while maintaining the strength of the mold. An object of the present invention is to provide artificial marble and a composition for artificial marble that are easy to release and have good productivity.

[0009]

SUMMARY OF THE INVENTION The gist of the present invention is to provide an acrylic component (A) containing methyl methacrylate and a methyl methacrylate unit as the main components with an average particle diameter of 5 to 30 .mu.m. 10 to 400 parts by weight of a surface-treated inorganic filler (B), 0.001 to 1 part by weight of a radical polymerization initiator (C) of a thermal polymerization initiation system, and a release agent (D)
In the composition for artificial marble containing 0.04 to 10 parts by weight. The gist of the present invention is an artificial marble obtained by polymerizing and curing the above-described composition for artificial marble.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The acrylic component (A) constituting the composition for artificial marble of the present invention contains methyl methacrylate (hereinafter referred to as "MMA" as appropriate) and MMA units as main components. As the acrylic component (A), MMA alone, a syrup composed of a mixture of a polymer of MMA and MMA, a mixture of MMA and another monomer copolymerizable with MMA (hereinafter, “MMA-containing mixture” as appropriate) MM)
A syrup composed of a copolymer of the A-containing mixture and an MMA-containing mixture is exemplified. “Containing MMA and MMA unit as main components” refers to MMA in acrylic component (A).
Amount of MMA unit in (co) polymer containing MA unit and MM
It means that the total amount with the amount of the A monomer is 70% by weight or more.

Other monomers copolymerizable with MMA include methacrylates other than MMA such as butyl methacrylate, benzyl methacrylate and 2-ethylhexyl methacrylate; acrylates such as ethyl acrylate and butyl acrylate; N-phenyl Maleimide,
Maleimide derivatives such as N-cyclohexylmaleimide;
Hydroxy group-containing monomers such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate and 2-hydroxypropyl methacrylate; vinyl esters such as vinyl acetate and vinyl benzoate; methacrylamide;
Nitrogen-containing monomers such as acrylonitrile; epoxy-containing monomers such as glycidyl acrylate and glycidyl methacrylate; and polymerizable aromatic compounds having an ethylenically unsaturated bond in the molecule such as styrene and α-methylstyrene. .

The acrylic component (A) is preferably a syrup obtained by polymerizing a part of MMA or a part of an MMA-containing mixture in a continuous or batch reactor. It is also preferable that the syrup is obtained by dissolving a polymer of MMA or a copolymer of a mixture containing MMA in MMA or a mixture containing MMA. The (co) polymer content in these syrups is preferably from 10 to 35% by weight. In the present invention, an advantage of using a syrup as the acrylic component (A) is that when the inorganic filler (B) is added to the acrylic component (A), the viscosity of the syrup is adjusted so that the inorganic filler (B) can be used. That is, sedimentation can be prevented, and in polymerizing the composition for artificial marble, polymerization time can be shortened, and productivity can be improved.

In the present invention, the acrylic component (A) may contain a crosslinkable vinyl compound having two or more vinyl groups in a molecule. Examples of the crosslinkable vinyl compound include ethylene glycol dimethacrylate, allyl acrylate, allyl methacrylate, divinylbenzene, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate,
6-hexanediol diacrylate, 1,6-hexanediol dimethacrylate, unsaturated polyester prepolymer derived from at least one kind of polycarboxylic acid including ethylenically unsaturated polycarboxylic acid and at least one kind of diol, etc. Is mentioned.

The inorganic filler (B) contained in the acrylic component (A) includes calcium carbonate, alumina, glass fiber, aluminum hydroxide, silica, talc, magnesium hydroxide, calcium hydroxide and the like. Of these, aluminum hydroxide is most preferred. The size of the inorganic filler (B) is 5 to 30 μm in average particle size.
When the average particle size is larger than 30 μm, the physical properties of the obtained artificial marble are reduced. When it is smaller than 5 μm, the light transmittance of the artificial marble decreases. Also, JIS P81
Hunter whiteness measured by a method according to No. 23 is 90%
As described above, the use of a high white type inorganic filler (B) of preferably 95% or more is more preferable because the color tone of the obtained artificial marble becomes good and the color tone can be easily adjusted.

[0015] The content of the inorganic filler (B) is 10 to 400 parts by weight based on 100 parts by weight of the acrylic component (A). When the content is less than 10 parts by weight, it becomes difficult to obtain a marble-like texture and weight. If it is higher than 400 parts by weight, the transparency and mechanical properties of the artificial marble will be reduced. The content of the inorganic filler (B) is more preferably from 40 to 400 parts by weight, even more preferably from 60 to 400 parts by weight.

[0016] The inorganic filler (B) must be surface-treated with a surface treatment agent such as a silane coupling agent, a titanate coupling agent, or a phosphoric acid coupling agent. As the surface treatment agent, alkoxysilane having a methacryl group such as γ-methacryloyloxypropyltrimethoxysilane is more preferable. When the surface-treated inorganic filler (B) is used, the strength, heat resistance, weather resistance, and hot water resistance of the artificial marble can be improved as compared with the untreated inorganic filler. The amount of the surface treatment agent used relative to the inorganic filler is preferably about 0.01 to 2 parts by weight based on 100 parts by weight of the inorganic filler.

With respect to 100 parts by weight of the composition for artificial marble of the present invention, the primary particle diameter is 5 to 50 nm, and the specific surface area is 50 to 400.
By adding 5 parts by weight or less of m ² / g silica fine particles, sedimentation of the inorganic filler (B) can be prevented. Examples of silica fine particles include JP-A-3-285854 and
What is described in -110498 gazette etc. is preferable.

In order to obtain a stone-like artificial marble, it is preferable that the composition for artificial marble contains colored or uncolored particles.

As the particles, a particle diameter of 0.1 obtained by crushing a resin or artificial marble in which an inorganic filler is dispersed in a resin is used.
Preferably, colored or uncolored particles of up to 5 mm are used. The particle size may be in a narrow range, for example, 0.24-2.8 mm. In addition, for example, a particle diameter of 0.1.
An opaque particle group having a color tone of 1 to 0.5 mm, and a particle diameter of 0.
A combination of opaque particles having a different color tone of 5 to 1.7 mm and translucent particles having a particle size of 1.7 to 5.0 mm, which have different particle diameters, may be used.

Further, for example, a particle having a particle diameter of 0.1 to 5 mm filled with a pigment having a transparency to a white color, a particle having a particle diameter of 0.1 to 5 mm filled with a pigment having a black color, and particles other than black and white May be a combination of particles having different color tones comprising particles having a particle diameter of 0.1 to 5 mm filled with the pigment of the present invention.

[0021] As the radical polymerization initiator (C) contained in the composition for artificial marble of the present invention, it is necessary to use a thermal polymerization initiator. A redox radical polymerization initiator is not preferable because the mold release from the mold tends to deteriorate when the composition for artificial marble is polymerized. As the radical polymerization initiator (C) of the thermal polymerization initiation system, 2,2′-
Azo compounds such as azobis (isobutyronitrile) and 2,2′-azobis (2,4-dimethylvaleronitrile);
Peroxyesters such as t-hexylperoxypivalate, t-butylperoxypivalate, t-butylperoxyneohexanoate, t-butylperoxyneodecanoate and cumylperoxyneodecanoate; Diacyl peroxides such as 2,4-dichlorobenzoyl peroxide and 2-methylbenzoyl peroxide, benzoyl peroxide, lauroyl peroxide, isobutyryl peroxide, bis (4-t-butylcyclohexyl) peroxydicarbonate, , 1-Bis (t-butylperoxy) cyclohexane, t-butylperoxylaurate, t-butylperoxyisopropyl carbonate, t-butylperoxyacetate, 2,2-
Bis (t-butylperoxybutane), t-butylperoxybenzoate, n-butyl-4,4-bis (t-
Organic peroxides such as butylperoxy) valerate. These can be contained alone or in combination. These radical polymerization initiators (C) can be appropriately selected depending on polymerization curing conditions such as temperature, time and cost. The content of the radical polymerization initiator (C) is 0.0 to 100 parts by weight of the acrylic component (A).
It is 01 to 1 part by weight.

Release agent (D) contained in the composition for artificial marble
Examples of the surfactant include various surfactants such as dioctyl sulfosuccinate, sodium dodecylbenzenesulfonate, and sodium N-lauroylsarcosinate; alkyl phosphates such as ethyl acid phosphate, butyl acid phosphate, and 2-ethylhexyl acid phosphate. , Stearic acid and its metal salts, stearic acid esters, stearyl alcohol, liquid paraffin and the like are preferred. Among these, dioctyl sulfosuccinate and alkyl phosphates are more preferred. From the viewpoint of releasability, the alkyl phosphate esters preferably have no polymerizable double bond. In order to improve the releasability from the mold, the content of the release agent (D) needs to be 0.04 to 10 parts by weight based on 100 parts by weight of the acrylic component (A). . If the amount of the release agent is less than 0.04 parts by weight, there is a problem in the releasability from the mold after the production of the artificial marble. If it is higher than 10 parts by weight, the physical properties of the obtained artificial marble will be reduced. When the addition amount of the release agent is within this range, excellent release properties can be obtained even in artificial marble having improved strength, heat resistance, weather resistance and hot water resistance using a surface-treated inorganic filler (B). Type characteristics can be imparted. Even when a metal mold is used, excellent release properties can be imparted.

The composition for artificial marble of the present invention may contain various components conventionally known as additive components of artificial marble in addition to the above-mentioned components.
For example, pigments such as white (titanium oxide, zinc sulfide), yellow (iron oxide yellow), black (iron oxide black), red (iron oxide red), and blue (ultramarine blue, phthalocyanine blue), dyes, ultraviolet absorbers, Examples include flame retardants, fluidizers, thickeners, polymerization inhibitors, antioxidants and the like.

[0024] The viscosity of the composition for artificial marble of the present invention is preferably 0.6 Pa · s or more at room temperature. If the viscosity is too low, the inorganic filler (B) will settle in the acrylic component (A), which is not preferable when polymerizing and curing to obtain artificial marble.

The composition for artificial marble of the present invention has good releasability when polymerized in a mold. As a method of polymerizing in a mold, as described above, the periphery is sealed with a gasket, a cell casting method in which a composition for artificial marble is injected between two opposed metal plates or glass plates and heated, or the same method. A space sealed with a pair of metal endless belts and a gasket that travels at the same speed in the direction,
Or continuous casting method, pressure molding method, injection molding method in which the composition for artificial marble is continuously injected and heated from the upstream of the space sealed with one metal endless belt, one film and gasket And a transfer molding method. A cell casting method and a continuous casting method are preferable. The artificial marble obtained by the cell casting method and the continuous casting method is a plate-like material, but an artificial marble having a shape other than the plate-like material can be obtained by another manufacturing method.

The artificial marble obtained by polymerizing and curing the composition for artificial marble of the present invention has extremely good strength, heat resistance, weather resistance and hot water resistance.

[0027]

The present invention will be described below with reference to examples. In these, "%" means% by weight and "part" means part by weight.

Example 1 The viscosity at 20 ° C. was 1.2 Pa
70 parts of MMA syrup having a polymerization rate of 20%, MM
100 parts of a syrup obtained by mixing 29 parts of A and 1 part of ethylene glycol dimethacrylate, 0.25 part of dioctyl sulfosuccinate as a release agent, and alkyl acid phosphate (trade name: Zelek UN, manufactured by DuPont)
One part was added and dissolved. While stirring this syrup with a mixer, the average particle size of the silane-treated surface was 8 μm,
150 parts of aluminum hydroxide powder (trade name: BW103ST, manufactured by Nippon Light Metal Co., Ltd.) having a hunter brightness of 99% were added little by little to obtain a slurry in which the aluminum hydroxide powder was uniformly mixed in the syrup. Thereafter, t-hexyl peroxypivalate (trade name: Perhexyl PV, manufactured by NOF Corporation) was used as a polymerization initiator for the slurry.
0.2 part was added and mixed uniformly to obtain a composition for artificial marble. The viscosity of this composition at 20 ° C. is 1.4 Pa ·
s.

After defoaming the obtained composition in a vacuum vessel, it is formed from two stainless steel plates mirror-finished in a square of 1.5 mm in thickness and 300 mm on a side and a gasket made of polyvinyl chloride. Poured into a mold. Then 80 ° C
For 1 hour at 120 ° C. for 1 hour,
An artificial marble plate having a thickness of 3 mm was obtained. The releasability of the artificial marble plate from the stainless steel plate was good.

Comparative Example 1 A composition was polymerized in the same manner as in Example 1 except that the amounts of the release agent were 0.005 parts of dioctyl sulfosuccinate and 0.02 parts of alkyl acid phosphate. This artificial marble plate could not be released from the stainless steel plate.

Example 2 The viscosity at 20 ° C. is 1.2 Pa
In 100 parts of syrup obtained by mixing 99 parts of methyl methacrylate having a polymerization rate of 20% and 1 part of ethylene glycol dimethacrylate, 0.8 part of dioctyl sulfosuccinate and 0.8 part of alkyl acid phosphate are used as a release agent. Was added and dissolved. While stirring the syrup with a mixer, the average particle size of the silane-treated surface was 1
Aluminum hydroxide powder of 5 μm, Hunter whiteness 99% (trade name: BW153ST, manufactured by Nippon Light Metal Co., Ltd.) 6
7 parts were added little by little to obtain a slurry in which the aluminum hydroxide powder was uniformly mixed in the syrup. Thereafter, 0.2 parts of t-hexyl peroxypivalate as a polymerization initiator was added to the slurry and mixed uniformly to obtain a composition for artificial marble. The viscosity of this composition at 20 ° C. was 2.7 Pa · s.

After defoaming the obtained composition in a vacuum vessel, an artificial marble plate having a thickness of 3 mm was manufactured using a continuous casting apparatus. In this device, a pair of stainless steel endless belts with a thickness of 1.5 mm and a width of 1500 mm whose significant surfaces are mirror-finished are installed substantially horizontally, only the lower belt is driven, and the endless belt is held by a group of rollers. Have been. The composition for artificial marble was continuously injected into a mold formed by two gaskets made of polyvinyl chloride and a pair of endless belts, and polymerized. The total length of the device is 90m, the first heating zone 60m at the front is heated by spraying hot water of 80 ° C from the outer surface of the endless belt like a shower, and the second heating zone 10m at the rear is heated in an air furnace at 120 ° C. Have been. The remaining 20 m is a cooling zone. The running speed of the endless belt was 1.5 m / min.

[0033] The releasability of the artificial marble plate from the endless belt was good. The obtained artificial marble plate had a smooth surface and a transferred endless belt surface, and was excellent in design without defects.

[0034]

The composition for artificial marble of the present invention has good releasability from a mold even when polymerized and cured by using a metal mold, and has particularly high productivity in a cell casting method and a continuous casting method. Good. Further, the obtained artificial marble is excellent in strength, heat resistance, weather resistance and hot water resistance.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Koji Nishida, Inventor 20-1 Miyukicho, Otake City, Hiroshima Prefecture Inside Mitsubishi Rayon Co., Ltd.

Claims (2)

[Claims] 1. An inorganic filler (B) having an average particle diameter of 5 to 30 μm and having been subjected to a surface treatment, based on 100 parts by weight of an acrylic component (A) containing methyl methacrylate and methyl methacrylate units as main components. A) a composition for artificial marble containing 10 to 400 parts by weight, 0.001 to 1 part by weight of a radical polymerization initiator (C) of a thermal polymerization initiation system, and 0.04 to 10 parts by weight of a release agent (D). 2. An artificial marble obtained by polymerizing and curing the composition for artificial marble according to claim 1.