JPS61243804A - Production of heat-resistant artificial marble - Google Patents

Abstract

PURPOSE:To obtain an artificial marble excellent in heat resistance and appearance, by adding an inorganic filler of specified properties and a curing agent to a polymerizable syrup derived from a methacrylate ester and a monomaleimide. CONSTITUTION:A polymerizable syrup is prepared by using a monomer mixture based on a methacrylate ester (e.g., methyl methacrylate) and monomaleimide (e.g., N-methylmaleimide) as a starting material. To 60-150pts.wt. polymerizable syrup, 40-85pts.wt. inorganic filler essentially consisting of a hydrated inorganic filler having an average particle diameter of 0.5-60mu and a dehydration initiation temperature as determined by DSC at a temperature rise rate of 20 deg.C/ min>=250 deg.C (e.g., aluminum hydroxide) and a curing agent for the syrup (e.g., benzoyl peroxide) are added. The obtained mixture after thorough mixing is cast into a mold and cured to obtain the purpose heat-resistant artificial marble.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing artificial marble used as building materials, etc., and particularly to a method for providing a product with excellent heat resistance and flame retardance.

Conventionally, methyl methacrylate polymerizable syrup cured with alumina trihydrate as a filler and unsaturated polyester resin cured with alumina trihydrate as a filler have been frequently used as artificial marble. Although these artificial marbles are flame retardant, they lack heat resistance and cause defects such as blistering and whitening at temperatures of about 200°C. In order to improve this problem, methods have been proposed in which alumina containing 1.8 to 2.9 mol of bound water is used or gibbsite-type aluminum hydroxide containing 0.1% or less of total N820m is used as a filler. These methods have been shown to improve heat resistance to a certain extent, but transparency may sometimes be insufficient, and there is a current demand for products that are more heat resistant and have an excellent celestial stone appearance. It is.

As a result of various studies to satisfy these current demands, the inventor of the present invention has decided to improve heat resistance by copolymerizing monomaleimides with methacrylic esters, and at the same time consider the appearance when hardened by mixing fillers. Heat resistance can be improved without impairing the cured product or appearance by using a polymerizable syrup and combining it with an inorganic filler that requires a water-containing inorganic filler with a specific dehydration start temperature as a filler. They discovered this and completed the present invention.

That is, the present invention provides polymerizable syrups derived from methacrylic acid esters and monomaleimides as main components.
The average particle size is 0.5 to 60μ at 20℃ at the top of 15 layers.
40 to 85 parts by weight of an inorganic filler, which must be a water-containing inorganic filler with a dehydration start temperature of 250°C or higher as measured by DSC when heated at a heating rate of /min, and a curing agent for the syrup are mixed and kneaded well. The present invention relates to a method for producing artificial marble, which is characterized by being heat resistant, having a marble appearance, and flame retardancy, by subsequently injecting it into a mold and curing it.

The polymerizable syrup that can be used in the present invention includes methacrylic acid monoesters such as methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, t-butyl methacrylate, isobutyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, toluyl methacrylate, and xylyl methacrylate, and N-methyl maleimide, N-butylmaleimide, N-phenylmaleimide, N-para-carboxyphenylmaleimide,
Syrup in which the copolymerization reaction with a monomaleimide such as N-cyclohexylmaleimide is stopped midway by means such as rapid cooling, or the (co)polymerization reaction of the methacrylic acid monoester and/or monomaleimide is carried out by suspension polymerization. It can be obtained by dissolving the resulting (co)polymer in monomers of the same or different composition. Ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, and neopentyl, which are polyfunctional (meth)acrylates higher than di(meth)acrylate, are used to increase the curing reactivity and heat resistance of the syrup. glycoldi (
meth)acrylate, trimethylolpropane tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, hydrogenated bisphenol A-di(meth)acrylate
Acrylate, xylylene glycol di(meth)acrylate, bisphenol A-dioxypropyl glycol di(meth)acrylate, tri(meth)acrylate of trishydroxyethyl isocyanurate, etc. can also be used. Furthermore, acrylic acid, methacrylic acid, and amides of these acids with organic amines, such as dimethacrylamide of methylenebisaniline, may be used as necessary to improve affinity with inorganic fillers and improve heat resistance. May be used. Styrene, p-methylstyrene, α-methylstyrene, etc., which are copolymerizable with the above monomers, may also be used in an amount of 30% or less of the methacrylates.

There are many types of inorganic fillers that can be used in the present invention.
For example, calcium hydroxide, zirconium hydroxide, barium hydroxide, magnesium hydroxide, aluminum hydroxide,
Aluminum/calcium hydroxide, borax, aluminum/potassium silicate, aluminum/calcium silicate, calcium metasilicate, calcium metaphosphate, etc., with an average particle size of 0.5 to 60μ, at a heating rate of 20℃/min. The dehydration start temperature according to DSC measurement when heated is 25
It is essential to use materials above 0°C alone or in combination, and in addition to these, calcium carbonate, alumina, silica sand,
General fillers such as glass powder can also be used together.

However, if a large amount of general filler is used in combination, the heat resistance of the resulting product will be reduced, so it is preferable that the amount is 60% by weight or less based on the total inorganic filler.

Note that when coloring is required, inorganic or organic pigments can be used, and inorganic oxide pigments are preferred coloring materials.

To carry out the present invention, a polymerizable syrup is prepared by a known method by combining the above-mentioned methacrylic esters and monomaleimides. It is preferable to blend so that the deformation temperature is 80° C. or higher and the refractive index at room temperature is 1.49 to 1.58. For example, when using cyclohexylmaleimide or phenylmaleimide as monomaleimides, 70 to 90 parts by weight of methacrylic esters, 10 to 30 parts by weight of monomaleimides, and 5 parts by weight or less of polyfunctional (meth)acrylates. is a suitable syrup composition, and 30% by weight or less of the methacrylic acid ester can be replaced with styrene, p-methylstyrene, α-methylstyrene, etc. Syrup is usually 60-15
An overlapping part is used, but if it exceeds 60 parts by weight, the flame retardance will be insufficient, and if it is less than 15 parts by weight, it will be difficult to mix the filler.

In the syrup, an organic peroxide which is a radical polymerization initiator and, if necessary, an accelerator or a bisazo compound as a curing agent for syrup are dissolved in advance in a ratio of 3 parts by weight or less, and then 40 to 85 parts by weight of a filler is added. There is crosstalk at a rate of . After mixing thoroughly using an extrusion mixer, etc., remove air bubbles by means such as vacuuming, pour into a mold, and proceed with curing at room temperature or 60 to 80°C, and if necessary to 100 to 120°C. Post-curing is performed to complete curing, and the product is removed from the mold and finished. The product thus obtained has a high heat deformation temperature, excellent thermal decomposition properties, is H-flammable, has a beautiful celestial stone appearance, and has excellent mechanical strength, making it suitable for building materials, especially kitchen countertops. It is useful as a member for applications requiring heat resistance.

Hereinafter, the present invention will be explained in more detail by giving examples.

Example 1 A solution obtained by dissolving 20 parts by weight of cyclohexylmaleimide in 80 parts by weight of methyl methacrylate monomer and adding 0.3 parts by weight of azopisbutyronitrile was dissolved in 0.2% by weight of polyvinyl alcohol. water medium 20
0 parts by weight at 80°C for 3 hours, then at 90°C.
After proceeding with polymerization for 2 hours, the copolymer particles were washed separately,
A copolymer of methyl methacrylate and cyclohexyl maleimide (average molecular weight approximately 100,000) was obtained. Next, this copolymer was dissolved in a monomer mixture consisting of 78 parts by weight of methyl methacrylate, 20 parts by weight of cyclohexyl maleimide, and 2 parts by weight of dipentaerythritol hexaacrylate at room temperature with stirring, and the copolymer-containing mixture was dissolved. layer is 28% by weight
A methyl methacrylate-cyclohexyl maleimide copolymer syrup was obtained. Next, 100 parts by weight of the syrup was heated at a gastric temperature rate of 20° C./min to the dehydration start temperature measured by DSC (hereinafter simply referred to as dehydration start temperature).

) is 255℃ hydrated alumina (average particle size 16μ) 15
0.50 parts by weight of lauryl peroxide α and 0.51 parts by weight of benzoyl peroxide were blended and kneaded well. After degassing under reduced pressure, the mixture was poured into a mold assembled with 200 x 200 x 10 aa+ glass plates, and heated at 60°C for 3 hours. After curing at 100° C. for 2 hours, an astronomical stone-like molded plate with a semi-transparent pattern was obtained. Table 1 shows the measurement results of the heat resistance of this plate.

Comparative Example 1 A methyl methacrylate polymer syrup was prepared in the same manner as in Example 1 except that cyclohexylmaleimide was not used. Using the obtained syrup, a molded plate was produced using the same filling material and curing method as in Example 1. The molded plate had a white appearance, but was somewhat lacking in translucency. In addition, the measurement results of the heat resistance of the molded plate were
Shown in the table.

Comparative Example 2 In Example 1, the dehydration start temperature was 220°C as a filler.
A molded plate was produced in the same manner as in Example 1 except that ordinary alumina trihydrate was used.

Although the appearance of the molded plate was good, the heat resistance was inferior to that obtained in Example 1, as is clear from Table 1.

Example 2 40% by weight of cyclohexyl methacrylate, 20% by weight of isobutyl methacrylate, 30% by weight of methyl methacrylate
0.2 parts by weight of 7zobisisobutyronitrile was added to 100 parts by weight of a monomer mixture containing 10% by weight of cyclohexylmaleimide, the temperature was raised to 80°C for 30 minutes, and the temperature was maintained for another 30 minutes, followed by rapid cooling. A syrup with the same composition of monomers and a copolymer content adjusted to 15% by weight was prepared.

0.2 parts by weight of 7zobisisobutyronitrile was dissolved in 100 parts by weight of this syrup, and the dehydration starting temperature was 250°C.
400 parts by weight of hydrated alumina with an average particle size of 30 μm was blended and kneaded, extruded after degassing, poured into a mold, heated at 70°C for 3 hours, and at 100°C for 2 hours to proceed with curing.
A 00x10-sized flat plate with an astronomical stone-like transparency was obtained.

The heat resistance of this flat plate was excellent as shown in Table 1.

Example 3 Methyl methacrylate 601111%, styrene 101
A copolymer (average molecular weight approximately 100,000) was prepared in the same manner as in Example 1 using a solution in which 2 parts by weight of benzoyl peroxide was dissolved in 100 parts by weight of a heptamer mixture containing 11% and 30% by weight of cyclohexylmaleimide. I got it.

Next, this copolymer was dissolved in a monomer mixture consisting of 60 parts by weight of methyl methacrylate, 10 parts by weight of styrene, and 30 parts by weight of cyclohexylmaleimide in the same manner as in Example 1, so that the copolymer content was 25% by weight. of syrup was obtained.

The refractive index of the cured product of this copolymer was 1.50.

Example 1 was prepared by blending 20,011 parts of hydrated alumina (average particle size 25 μm) with a dehydration start temperature of 250°C, 0.5 parts by weight of lauryl peroxide, and 0.5 parts by weight of benzoyl peroxide into 100 parts by weight of the syrup. Curing was performed in the same manner as above to obtain an astronomical stone-like molded plate with semi-transparent opacity. Table 1 shows the measurement results of the heat resistance of this plate.

Example 4 In Example 3, the syrup was 100 Ml! A molded plate was prepared in the same manner as in Example 3, except that 8011 parts of hydrated alumina was used for 1, and the heat resistance was measured. Table 1 shows the results.

Example 5 A solution of 1.5 parts by weight of lauryl peroxide dissolved in 100 parts by weight of a monomer mixture of 45% by weight of methyl methacrylate, 15% by weight of isobutyl methacrylate, 15% by weight of p-methylstyrene and 25% by weight of 0-chlorophenylmaleimide was prepared. A copolymer (average molecular weight: about 120,000) was obtained in the same manner as in Example 1.

Next, this copolymer was dissolved in a monomer mixture consisting of 45 parts by weight of methyl methacrylate, 15 parts by weight of isobutyl methacrylate, 15 parts by weight of p-methylstyrene, and 25 parts by weight of O-chlorophenylmaleimide in the same manner as in Example 1. , a syrup with a copolymer content of 25% by weight was obtained.

100 parts by weight of the syrup were blended with 200 parts by weight of hydrated alumina (average particle size 25μ) with a dehydration start temperature of 250°C, 0.5 parts by weight of lauryl peroxide, and 11 parts by weight of benzoyl peroxide to produce Example 1. Curing was performed in the same manner as above to obtain an astronomical stone-like molded plate with semi-transparent opacity. Table 1 shows the measurement results of the heat resistance of this plate.

Claims (1)

[Claims] 1. 60 to 15 parts by weight of a polymerizable syrup containing methacrylic acid esters and monomaleimides as main components, with an average particle size of 0.5 to 60μ, was heated at a heating rate of 20°C/min. Dehydration start temperature according to DSC measurement is 25
40 to 85 parts by weight of an inorganic filler (essentially a water-containing inorganic filler having a temperature of 0°C or higher) and a curing agent for the syrup are blended together, thoroughly kneaded, and then poured into a mold and cured. Marble manufacturing method.