JPS6333458A - Artificial marble having improved fireproofing performance and production thereof - Google Patents

Abstract

PURPOSE:To obtain artificial marble having improved fireproofing performance, by blending a resin phase consisting of a polymer comprising methyl methacrylate as a main component and an acrylonitrile-styrene copolymer resin with aluminum hydroxide and molding. CONSTITUTION:(A) 20-80pts.wt. syrup consisting of A1:5-40wt% acrylonitrile- styrene copolymer having 20-50mol% acrylonitrile content and 0.2-2dl/g intrinsic viscosity and A2: 95-60wt% polymer comprising methyl methacrylate as a main component is blended with (B) 80-20pts.wt. aluminum hydroxide powder having <=100mum, preferably <=50mum particle diameter, fed to a mold, molded and cured.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an aluminum hydroxide powder-filled methyl methacrylate-based artificial marble having excellent fire retardant performance and a method for producing the same.

(Prior art) Polymer molded products whose main component is methyl methacrylate filled with aluminum hydroxide powder have a deep and beautiful surface, excellent mechanical strength, excellent weather resistance, and corrosion resistance. Due to its properties such as excellent durability and flame retardancy, artificial marble products are used in various table tops, countertops, bathroom vanities, sinks, bathtubs, shower trays, waterproof pans, flooring materials, wall materials, Widely used for partition boards, arts and crafts, etc. The flame retardance of this artificial marble product is due to the aluminum hydroxide powder contained as a filler containing a large amount of bound water of 34.5% by weight, which causes a rapid dehydration decomposition reaction at around 200°C. At the same time, it absorbs a large amount of heat, and if a large amount of aluminum hydroxide powder is added to ordinary flammable plastic, it will meet the UL standard 94. It is also possible to impart flame retardancy that passes V-0. However, methyl methacrylate-based artificial marble filled with aluminum hydroxide powder has the disadvantage that the burning speed is high when exposed to flame, and the flame easily penetrates the back surface, so it is used for partition boards and wall materials. Then, in the case of a fire, the flame spreads quickly, which poses a problem in initial extinguishing.

In order to delay the penetration of flame to the back side, it is possible to increase the thickness of the artificial marble product, but this increases the material and transportation costs, which is economically disadvantageous.

In addition, a method of adding a large amount of flame retardant such as phosphorus-based yahalogen-based or antimony trioxide is also known, but this method uses aluminum hydroxide powder-filled methyl methacrylate-based artificial marble because of the large amount of flame retardant. The product's excellent depth, heat resistance, weather resistance, corrosion resistance, strength, and other properties will be lost. Therefore, it is desired to inexpensively improve the flame penetration resistance of methyl methacrylate-based artificial marble filled with aluminum hydroxide powder without impairing its excellent properties.

(Problems to be Solved by the Invention) The present invention aims to improve the fire-retardant performance of methyl methacrylate-based artificial marble products filled with aluminum hydroxide powder at a low cost without impairing the excellent properties thereof. This is to make it difficult for flame to penetrate even if it is roughened.

(Means for Solving the Problems) The present inventors have made intensive studies to solve the above problems, and as a result, have completed the present invention. That is, a resin consisting of an acrylonitrile-styrene copolymer resin in an amount of 5 to 40% by weight based on the total amount of the resin phase and a polymer whose main component is methyl methacrylate in an amount of 95 to 60% by weight based on the total amount of the resin phase. Artificial marble consisting of 20 to 80 parts by weight of a phase and 80 to 20 parts by weight of aluminum hydroxide powder (however, the total amount of the resin phase and aluminum hydroxide powder is 100 parts by weight) has excellent fire retardant performance. They found that it was difficult for flame to penetrate to the back side.

Although such artificial marble can be produced by various methods, it is preferably made by combining 5 to 40% by weight of 7-crylonitrile-styrene copolymer resin and 95 to 95% by weight based on the total amount of syrup.
20 to 80 parts by weight of syrup consisting of a polymerizable monomer mainly composed of 60% by weight of methyl methacrylate and 80 to 20 parts by weight of aluminum hydroxide powder in a total amount of 10
It is manufactured by mixing the mixture to a total weight of 0 parts by weight, introducing it into a mold, and molding and curing it.

The polymer containing methyl methacrylate as a main component in the present invention refers to a polymer of polymerizable monomers containing methyl methacrylate as a main component. The polymerizable monomer containing methyl methacrylate as a main component herein refers to methyl methacrylate alone or less than 50% by weight of methyl methacrylate substituted with other α,β-unsaturated compounds. The α,β-unsaturated compound that can substitute for methyl methacrylate is not particularly limited as long as it is compatible with methyl methacrylate and can be copolymerized with methyl methacrylate; examples of such compounds include acrylic acid and methacrylic acid. , esters of monohydric alcohols with 1 to 18 carbon atoms and acrylic acid, esters of monohydric alcohols with 2 to 18 carbon atoms and methacrylic acid, olefinic nitriles such as acrylonitrile and methacrylonitrile, acrylamide and methacrylamide olefinic amides such as, aromatic unsaturated compounds such as styrene and α-methylstyrene, monofunctional monomers such as vinyl esters such as vinyl acetate and vinyl benzoate, and acrylic and methacrylic acids with ethylene glycol and polyethylene glycol, polypropylene glycol,
1,3-butanediol, neopentyl glycol, 1
, 6-hexanediol, trimethylolethane, trimethylolpropane, tetramethylolmethane, pentaerythritol, dipentaerythritol, and other polyesters with polyhydric alcohols such as divinylbenzene, diallyl phthalate, triallyl cyanurate, etc. Examples include, but are not limited to, monomers. Two or more types of α,β-unsaturated compounds that can substitute for methyl methacrylate may be used.

Furthermore, a part of the composition of the polymerizable monomer containing methyl methacrylate as a main component can be polymerized in advance and used as a polymer solution.

The acrylonitrile-styrene copolymer resin used in the present invention may become transparent or semi-milky in order to give the artificial marble product a sense of depth when blended with a polymer whose main component is methyl methacrylate. Most preferably, it is necessary and transparent. The composition of an acrylonitrile-styrene copolymer resin having such properties varies depending on the composition of the polymer whose main component is methyl methacrylate, but generally it is an acrylonitrile-styrene copolymer resin composition with an acrylonitrile content of 20 to 50. The intrinsic viscosity measured at 25° C. using tetrahydrofuran as a solvent is 0.2 to 2.0 di)10, preferably 0.5 to 1. It is OdN/g. For example, if the polymer containing methyl methacrylate as a main component is a methacrylic resin and the resin composition has a 7-acrylonitrile content of 40 mol% as a raw material for the acrylonitrile-styrene copolymer resin, the blended product will be transparent.

The amount of acrylonitrile-styrene copolymer resin added to the polymer mainly composed of methyl methacrylate is 5 to 40% by weight, preferably 10 to 25% by weight based on the total amount of the resin phase.
Weight%. If the amount of the acrylonitrile-styrene copolymer resin added is less than 5% by weight, the fireproof performance will hardly improve, and if it exceeds 30% by weight, the properties such as weather resistance of the artificial marble product will deteriorate, which is not preferable.

The aluminum hydroxide powder used in the present invention is not particularly limited, but the particle size is 200 μm or less, preferably 100 μm or less, and more preferably 50 μm or less. The amount of aluminum hydroxide powder added to the resin phase is
Although it is naturally determined by the depth, specific gravity, hardness, strength, heat resistance, price, etc. of the desired artificial marble product, it is usually 20 to 80% by weight, preferably 40 to 75% by weight, based on the total amount of both. %. If the amount of aluminum hydroxide powder added exceeds 80% by weight, the depth of the artificial marble product will be lost and properties such as strength will deteriorate, which is not preferable. If the amount added is less than 20% by weight, properties such as hardness, heat resistance, and flame retardance will be poor, which is not preferable.

In the present invention, there are no particular limitations on the method of mixing each component to obtain a product. For example, a polymer mainly composed of methyl methacrylate and an acrylonitrile-styrene copolymer resin can be mixed under melting conditions, and then aluminum hydroxide powder can be added and mixed to form the mixture, or cast molding can be carried out. It is also possible to obtain the product at That is, in syrup made by dissolving 7crylonitrile-styrene copolymer resin in a polymerizable monomer mainly composed of methyl methacrylate,
A product is obtained by introducing a slurry containing aluminum hydroxide powder into a mold and molding and hardening it.The cast molding method has low manufacturing costs and easy operation, and also has the stain resistance of artificial marble products. It has the advantage that it is easy to introduce a crosslinked structure to improve heat resistance. There is no particular restriction on the method of obtaining the syrup or slurry. For example, 7crylonitrile-styrene copolymer fat is added to a polymerizable monomer mainly composed of methyl methacrylate with stirring, and then heated or Syrup can be made by continuing stirring until dissolved while cooling, and syrup and aluminum hydroxide powder can be mixed in a tank equipped with an agitator or a kneader.
This can be done using The obtained slurry may be directly introduced into a mold and molded and cured, but before that, it may be subjected to a thickening operation or a part of the curing reaction is advanced to form SMC or BMG, and then introduced into a mold and molded and cured. It is also possible to do so. Therefore, the molding and curing according to the present invention is not limited to molding using a closed cell device, a covered open cell device, an open mold, etc., but also molding using a continuous pour molding device, and the above-mentioned SMC, BMC, etc. using a compression molding device, an injection molding device, etc. It also includes the molding of

In addition, in cast molding, if the amount of acrylonitrile-styrene copolymer resin added is less than 5% by weight based on the total amount of syrup, the slurry may have no stickiness and may be difficult to flow when introduced into the mold, or hydroxylation may occur. The aluminum powder may settle and separate, and if it exceeds 30% by weight, the viscosity of the slurry becomes high, making it difficult to mix and introduce into a mold, which is not preferable. Furthermore, if the amount of aluminum hydroxide powder added to the total amount of syrup and aluminum hydroxide powder exceeds 80% by weight, the viscosity of the slurry will increase, which is not preferable.

The curing method according to the present invention is not particularly limited, and examples thereof include heating in the presence or absence of a radical polymerization initiator, a method using a so-called redox system consisting of a radical polymerization initiator and an accelerator, and irradiation with ultraviolet rays or radiation. It can be carried out by any method such as, but is not limited to. When performing cast molding, usually
This is carried out by heating to a temperature of 20 to 130°C, preferably 50 to 90°C, in the presence of a radical polymerization initiator.

Examples of radical polymerization initiators include azo compounds such as 2,2°-azobisisobutyronitrile and 2,2''-azobis(2,4-dimethylvaleronitrile), diisopropyl peroxydicarbonate, and di(methoxyisopropyl). There are peroxides such as peroxydicarbonate, t-butylperoxyneodecanoate, lauroyl peroxide, benyl peroxide, and 2,2-bis(t-butylperoxy)butane, which are based on the total amount of syrup. It is used in an amount of 0.005 to 3% by weight, preferably 0.01 to 1% by weight.

The artificial marble products of the present invention may contain all or part of the polymerizable monomer composition mainly composed of methyl methacrylate as described above and acrylonitrile-styrene as long as the properties are not impaired. Polymers other than copolymer resins, fillers other than aluminum hydroxide powder, dyes and pigments, reinforcing materials, modifiers, stabilizers, mold release agents, lubricants, flame retardants, polymerization accelerators, polymerization initiator residues, It is also possible to include polymerization regulator residues and the like.

(Example) The present invention will be explained in more detail with reference to Examples below.
The present invention is not limited in any way by these Examples.

Examples 1 to 6 Acrylonitrile-styrene copolymer resin (Sevian N, 0
Aluminum hydroxide powder (
Hisilite H-310. 65 parts by weight (manufactured by Showa Light Metal Co., Ltd.) were mixed to obtain a slurry. 100 parts by weight of this slurry was mixed with 0.02 parts by weight of stearic acid and 0.02 parts by weight of 2,2°-azobisisobutyronitrile, and a soft gasket was placed between two glass plates in a U-shape. The mixture was poured into a sandwiched mold, and the mold was kept in water at 60° C. for 5 hours and then in an air bath at 120° C. for 5 hours to obtain a casting plate with a thickness of 15 mm. All of these exhibited beautiful surface properties with excellent depth. Further, accelerated exposure was performed for 1000 hours using a fade-o-meter, but no yellowing was observed. Separately, the casting board was held vertically, and a flame adjusted to a certain size was radiated perpendicularly to the casting board surface from a gas burner installed 50,111 meters away from the board surface. The rate at which the burn thickness decreases was measured. The results are shown in Table 1. This shows that the flame burning speed of the artificial marble of the present invention is low, making it difficult for the flame to penetrate to the back surface.

(Left below) Comparative Example 1 Syrup obtained by partially polymerizing methyl methacrylate (2
A casting plate was obtained by the same method as in Examples 1 to 6, except that 35 parts by weight of syrup consisting of 95% by weight (viscosity at 5°C of 2.5 poise) and 5% by weight of trimethylolpropane trimethacrylate was used. Ta. The rate of decrease in thickness due to flame measured under the same conditions as in Examples 1 to 6 was 1°5 Qmm/min as shown in Table 1.

Comparative Example 2 Mixed top layer consisting of 50 parts by weight of methyl methacrylate and 5 parts of trimethylolpropane trimethacrylate
A syrup was obtained by dissolving 45 parts by weight of the same acrylonitrile-styrene copolymer resin as in Examples 1 to 6. A casting plate was obtained by the same operation as in Examples 1 to 6 except for using 35 parts by weight of this syrup. However, in this comparative example, the slurry had a high viscosity and could not be poured into the mold, so the mold was opened, the slurry was placed between glass plates, and the slurry was crushed to a predetermined thickness. Therefore, the slurry does not spread throughout the mold,
Moreover, the resulting casting plate was incompletely defoamed and contained bubbles. Using a fade-o-meter, cast this casting plate for 10 minutes.
Yellowing was observed when accelerated exposure was performed for 0.01 hours.

Example 7 A mixed monomer consisting of 44.45 parts by weight of methyl methacrylate and 1.755 parts by weight of 1.3-butanediol dimethacrylate was mixed with an acrylonitrile-styrene copolymer resin (DEN AS, Chemical industry (
Co., Ltd.) and methacrylic resin (Parabeads H).
A slurry was obtained by mixing 40 parts by weight of the same aluminum hydroxide powder as in Examples 1 to 6 into a syrup obtained by dissolving 1.8 parts by weight of Al.R, manufactured by Kyowa Gas Chemical Industry Co., Ltd. From this, the casting plate obtained by the same operation as Examples 1 to 6,
The rate of thickness reduction due to flame measured under the same conditions as Examples 1 to 6 was 1.75 mm/min.

Comparative Example 3 A syrup obtained by dissolving 15 parts by weight of the same methacrylic resin as in Example 7 in a monomer mixture consisting of 43.25 parts by weight of methyl methacrylate and 1.75 parts by weight of 1,3-butanediol dimethacrylate is used. Except for this, the thickness reduction rate due to flame measured under the same conditions as Examples 1 to 6 of the casting plate obtained by the same operation as Example 7 was 1.9.
The speed was 2 mm/min.

(Effects of the Invention) The present invention improves fire retardant performance, i.e. flame resistance, by adding an acrylonitrile-styrene copolymer resin to a polymer molded product whose main component is methyl methacrylate filled with aluminum hydroxide powder, that is, an artificial marble product. This improves the flame penetration resistance when exposed to flame.

The method of adding the acrylonitrile-styrene copolymer resin according to the present invention does not require increasing the thickness of the product, compared to the conventional method of increasing the thickness of the product or adding a large amount of flame retardant, so material costs and transportation costs are reduced. Also, unlike flame retardants, acrylonitrile-styrene copolymer resin does not reduce properties such as depth, strength, hardness, weather resistance, and corrosion resistance. This made it possible to improve flame penetration resistance while maintaining excellent properties.

In addition, when producing the artificial marble products according to the present invention by cast molding, the syrup viscosity can be adjusted to an appropriate level by dissolving acrylonitrile-styrene copolymer resin in a polymerizable monomer whose main component is methyl methacrylate. The slurry obtained by adding aluminum hydroxide powder becomes sticky, and the fluidity of the slurry is maintained appropriately, making it easy to operate and preventing aluminum hydroxide powder from settling and separating during molding. It also has the advantage of not having to do anything.

Claims (2)

[Claims] (1) Based on the total amount of the composition, the following (A) and (
Artificial marble consisting of 20 to 80% by weight of a resin phase consisting of B) and 80 to 20% by weight of aluminum hydroxide powder. (A) 5 to 40% by weight acrylonitrile-styrene copolymer resin, based on the total amount of the resin phase. (B) A polymer based on 95 to 60% by weight of methyl methacrylate, based on the total amount of resin phase. (2) Based on the total amount of syrup, 20 to 80 weight percent of syrup is composed of 5 to 40 weight percent of acrylonitrile-styrene copolymer resin and 95 to 60 weight percent of a polymerizable monomer whose main component is methyl methacrylate. 80 to 20 parts by weight of aluminum hydroxide powder are mixed in a total amount of 100 parts by weight, and the mixture is introduced into a mold and molded and hardened.