JPH10219069A - Production of resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a production process for a resin that is suitable for hot- press molding and can produce acrylic artificial marble having good falling ball impact strength, beauty, heat resistance, chemical resistance and weather ability. SOLUTION: A syrup containing 100 pts.wt. of unsaturated monomers mainly comprising (meth)acrylic ester and 50-400 pts.wt. of methyl methacrylate polymer is kneaded with 25-240 pts.wt. of an inorganic filler per 100 pts.wt. of the syrup at 65-120 deg.C, preferably 70-120 deg.C. Then, a curing agent is admixed to the resultant clay-like kneaded product after or during the cooling step.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a resin composition, and more particularly to a method for producing an acrylic resin composition containing an inorganic filler, which is useful as a molding material for artificial marble.

[0002]

2. Description of the Related Art Acrylic artificial marble containing an inorganic filler in an acrylic resin makes use of its beautiful appearance and excellent characteristics to make use of kitchen tops, various counter tops, vanity tables, shower trays, flooring materials, and walls. Widely used for materials and partition boards. This acrylic artificial marble is generally cast-molded by polymerizing and curing an unsaturated monomer mainly composed of (meth) acrylic acid ester or a slurry obtained by dispersing an inorganic filler in a syrup thereof along a mold. It is manufactured by the method. However, this casting method requires a long curing time and has a disadvantage of low productivity.

As a method of shortening the curing time, a method of heating under pressure (hot press molding method) has been proposed.
In the hot press molding method, the raw material composition needs to have shape stability, and a low-concentration resin syrup similar to that used in the casting method, an inorganic filler, an aromatic vinyl compound, an isocyanate Compound (JP-A-5
There is known a method of adding a thickener such as a fine powder of a crosslinked polymer (JP-A-6-313019) to impart shape stability to a composition. However, in these methods, it takes a long time to thicken, requires a leaving time called aging time,
Further, there is a problem that the addition of the thickener tends to reduce the aesthetic properties, heat resistance, chemical resistance, weather resistance, and other characteristics of the acrylic artificial marble.

Further, a monomer containing a polyfunctional (meth) acrylate, a methacrylic resin powder, an inorganic filler, a curing agent and, if necessary, other additives are kneaded at room temperature or at a temperature lower than the curing temperature. There has been proposed a method of producing a resin composition having a shape stability which is a clay-like or solid at room temperature obtained by aging and subjecting it to hot press molding (Japanese Patent Publication No. 5-138999). This method has the advantage of not using a thickening agent that reduces the characteristics of the acrylic artificial marble, but requires an aging step for kneading at a low temperature, while discoloring the resin composition when kneading for a long time. In addition, there is a problem that the ball impact strength of the molded product is lowered.

[0005]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an acrylic artificial marble having good falling ball impact strength and good beauty, heat resistance, chemical resistance, weather resistance and the like. An object of the present invention is to provide a method for producing a resin composition suitable for a press molding method and the like.

[0006]

Means for Solving the Problems That is, the above object is as follows.
According to the present invention, a syrup composed of 100 parts by weight of an unsaturated monomer mainly composed of (meth) acrylate and 50 to 400 parts by weight of a methyl methacrylate-based polymer, and 25 to 240 parts by weight based on 100 parts by weight of the syrup This is achieved by a method for producing a resin composition in which a part by weight of an inorganic filler is kneaded at 65 to 120 ° C. and a curing agent is mixed with the obtained clay-like kneaded product after cooling or during the cooling process.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The unsaturated monomer mainly composed of (meth) acrylate used in the present invention refers to (meth) acrylate alone or a mixture of (meth) acrylate and another unsaturated monomer. . As the content ratio of the (meth) acrylate, the weather resistance of molded articles such as artificial marble,
From the viewpoints of beauty, chemical resistance, etc., usually 30% by weight or more is used, preferably 50% or more, more preferably 70% or more.

The (meth) acrylic acid ester includes, for example, an ester of methacrylic acid and a monohydric alcohol having 1 to 18 carbon atoms; an ester of acrylic acid and a monohydric alcohol having 1 to 18 carbon atoms; Polyhydric alcohols such as ethylene glycol, polyethylene glycol, polypropylene glycol, 1,3-butanediol, neopentyl glycol, 1,6-hexanediol, trimethylolethane, trimethylolpropane, tetramethylolmethane, pentaerythritol, and dipentaerythritol With esters, acrylic acid and ethylene glycol, polyethylene glycol, polypropylene glycol, 1,3-butanediol, neopentyl glycol, 1,6-hexanediol, trimethylolethane, trimethylo Trimethylolpropane, tetramethylolmethane, pentaerythritol, an ester of a polyhydric alcohol such as dipentaerythritol and the like,
These can be mixed and used. Of these, methyl methacrylate is particularly beautiful, heat resistant, chemical resistant,
This is preferable because a molded article having a good balance of weather resistance, strength, and the like can be obtained. Esters of polyhydric alcohol and methacrylic acid or acrylic acid are preferably used in applications requiring stain resistance and heat resistance.

Examples of other unsaturated monomers used as a mixture with the (meth) acrylic ester include acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, styrene, α-methylstyrene, vinyl acetate and the like. However, it is not limited to these.

The methyl methacrylate-based polymer used in the present invention has a ratio of methyl methacrylate of 30 due to the weather resistance, beauty, and chemical resistance of molded articles such as artificial marble.
% Or more is used, preferably 50% or more,
70% or more is more preferable. For example, a (meth) acryl other than methyl methacrylate and methyl methacrylate, such as a homopolymer of methyl methacrylate, a copolymer of methyl methacrylate and methyl acrylate, and a copolymer of methyl methacrylate and ethyl acrylate A copolymer of an acid ester and a copolymer of methyl methacrylate and styrene are preferably used. The weight average molecular weight of the methyl methacrylate-based polymer is preferably from 50,000 to 600,000, particularly from 70,000 to 2,000,000.
Those having a molecular weight of 100,000 are preferably used. The content of the methyl methacrylate polymer in the syrup is from 50 to 400 parts by weight, preferably from 80 to 400 parts by weight, based on 100 parts by weight of the unsaturated monomer mainly composed of (meth) acrylate.
300 parts by weight are used. When the amount is less than 50 parts by weight, the shape stability of the resin composition is inferior. On the other hand, when it exceeds 400 parts by weight, the fluidity of the resin composition is inferior, which is not preferable.

The syrup containing a methyl methacrylate polymer and an unsaturated monomer mainly composed of (meth) acrylate used in the present invention can be prepared by a known method, for example, by adding an acrylic polymer to an unsaturated monomer. May be prepared by a method such as adding and stirring under heating, but a kneader is preferably used because syrup has a high viscosity. As a preferred embodiment of the present invention, a method in which a syrup is produced by a kneader, an inorganic filler is subsequently added, and the mixture is kneaded at 65 to 120 ° C.

[0012] The shape of the methyl methacrylate-based polymer used in the preparation of the syrup is not particularly limited, but from the viewpoint of easy handling and shortening the time required for the preparation, the particle size of the polymer is 50 to 1000 µm. Granules are preferably used, and for example, a suspension polymer is preferably used. Further, as the methyl methacrylate-based polymer, a swelled state in which a part of unsaturated monomer mainly composed of (meth) acrylate ester is previously contained may be used.

As the inorganic filler used in the present invention, powders of aluminum hydroxide, aluminum oxide, calcium carbonate, calcium silicate, calcium aluminate, calcium sulfate, magnesium hydroxide, silica, talc, clay, glass and the like are used. However, the present invention is not limited to these. Among these, from the viewpoint of luxury, stain resistance and processing performance of acrylic artificial marble,
Aluminum hydroxide, magnesium hydroxide and silica are preferred, and aluminum hydroxide is particularly preferred. The particle size of the inorganic filler is usually 0.1 to 100 μm, more preferably 1 to 30 μm. Inorganic fillers that have been surface-treated, such as silane treatment, are also preferably used. The inorganic filler is used in an amount of 25 to 240 parts by weight, preferably 70 to 100 parts by weight, based on 100 parts by weight of the syrup.
200 parts by weight are used. 25 inorganic fillers
If the amount is less than the weight part, the hardness and heat resistance of the molded article decrease, while 2
If the amount exceeds 40 parts by weight, the fluidity of the resin composition decreases, which is not preferable.

The curing agent used in the present invention is not particularly limited, and preferred examples thereof include azobis compounds and organic peroxides which are radical polymerization initiators. For example, azobisisobutyronitrile, benzoyl peroxide, t- Butyl peroxide, cumene hydroxy peroxide,
t-butyl hydroperoxide, dicumyl peroxide, 1,1-di-t-butylperoxy-3,3,5
One or more of trimethylcyclohexane and the like can be used. The curing agent is used in a proportion of usually 1 to 10 parts by weight, preferably 3 to 7 parts by weight, based on 100 parts by weight of the unsaturated monomer mainly composed of (meth) acrylate.

[0015] The method of the present invention is characterized in that the syrup and the inorganic filler are kneaded at a temperature of 65 to 120 ° C.
It is common knowledge of a person skilled in the art that kneading of a polymerizable substance is performed at a low temperature near room temperature, but falling ball impact strength that cannot be realized by a composition manufactured by a conventional method by kneading at a high temperature is known. It has been found that a resin composition giving a molded article having a high degree of yield can be obtained, leading to the present invention. Kneading temperature is 6
It must be in the range of 5 to 120 ° C, preferably 70 ° C.
１００100 ° C. If the temperature is lower than 65 ° C., the falling ball impact strength becomes inferior. On the other hand, kneading at a temperature exceeding 120 ° C. is not preferred because polymerization of the monomer and decomposition of the polymer tend to occur. In order to knead at the above temperature, the kneading machine used for kneading usually has a temperature adjusting portion such as a jacket portion, and the kneading portion is predetermined by using an electric heater, steam, hot or cooling water, oil for temperature adjusting, or the like. It is preferable that the temperature can be adjusted so as to reach the temperature.

The kneading method is not particularly limited as long as the effects of the present invention can be realized. Examples thereof include a sigma-type blade kneader, a zet-type blade kneader, a spiral-type blade kneader, a blade-type continuous kneader, a paddle mixer, and a continuous kneader. Paddle mixers, ribbon mixers, co-kneaders, roll-type pressure kneaders, roll-type internal mixers, continuous kneaders, single-screw extruders, twin-screw extruders and the like are preferably used. The kneading time varies depending on the type of kneader, the number of rotations and the kneading temperature, but generally 2 minutes to 10 minutes is employed.

After the kneaded product is obtained, a desired resin composition can be produced by mixing the obtained clay-like material with a curing agent after cooling or during the cooling process. At this time, the method of mixing the curing agent is not particularly limited,
Various kneaders and mixers can be used. For example, the one used for the above kneading can be used again, or two kneaders can be used. The mixing time may be about several minutes to 30 minutes as long as it can be uniformly mixed, and about 1 to 5 minutes if a continuous twin-screw kneader is used. When the curing agent is a solid, it is preferable to dissolve it in a small amount of the monomer and to add it, because it is easily homogeneously mixed. The resin composition thus obtained has a clay-like shape, is free of stickiness, and is easy to handle such as measurement.

In the method of the present invention, fiber materials such as glass fibers, aramid fibers, carbon fibers, etc., various pattern materials, coloring Agents, coupling agents, light stabilizers,
Additives such as antioxidants, release agents, polymerization regulators, and defoamers can be used in combination.

The resin composition obtained by the method of the present invention can be molded and cured by a method such as compression molding, injection molding, or extrusion molding to obtain a molded product, particularly a marble-like product. As the molding conditions of the compression molding, the molding pressure is usually 10 to 200 kg / cm ² and the molding temperature is 80 to 180.
℃, molding time is about 10 minutes.

[0020]

The present invention will be described in more detail with reference to the following Examples, which by no means limit the scope of the present invention. The falling ball impact strength and colorimetry were measured and evaluated by the following methods.

(Measurement of Falling Ball Impact Strength) JIS K721
The 50% breaking energy was determined by the method of 1, and this was defined as the falling ball impact strength. Falling ball impact test equipment is JIS K67
The steel ball used is JIS ball type 2 (1 ± 1).
0.05 kg, diameter about 63 mm). The test piece size is a square of 150 ± 1 mm on one side.

(Colorimetry) SM-2 manufactured by Suga Test Instruments Co., Ltd.
It was measured with a colorimeter.

Example 1 Roll type pressure kneader [D-10 manufactured by Moriyama Seisakusho Co., Ltd.]
-20 type, mixing volume 10 liter], 1.425 kg of methyl methacrylate, 1.075 kg of neopentyl glycol dimethacrylate, polymer beads of methyl methacrylate [98 wt% of methyl methacrylate and 2 wt% of methyl acrylate] Coalescence, weight average molecular weight 11000
0, average particle diameter 0.3 mm] 2.625 kg of syrup, 6.85 kg of silane-treated aluminum hydroxide having an average particle diameter of 8 μm, and 1.175 kg of stone-like pattern material having an average particle diameter of 0.3 mm , And the temperature of the kneader jacket is raised to 80 ° C., and the mixture is kneaded for 10 minutes.
A 5 ° C. clay-like resin composition was obtained. 50 parts of this resin composition
After cooling to ℃, 50 g of 1,1-di-t-butylperoxy-3,3,5-trimethylcyclohexane was added and mixed for 3 minutes. 10 kg of the obtained resin composition is put into a vanity mold having a top plate portion of 600 mm × 1000 mm, a height of 50 mm and a front guard and a back guard, and a molding temperature of 130 ° C. and a pressure resin pressure of 100 kgf / c.
Pressure molding was performed under molding conditions of m ² and a pressure time of 12 minutes to obtain a 600 mm × 1000 mm × 10 mm acrylic artificial marble vanity. The obtained molded article had no molding defects such as cracks and had an extremely beautiful surface. 2. A 150 mm × 150 mm square sample was cut out from the vanity stand, and the falling ball impact strength was measured.
The molded article had a high falling ball impact strength of 0 J and was highly practical.

Example 2 Roll type pressure kneader [D-10, manufactured by Moriyama Seisakusho Co., Ltd.]
-20 type, 10 liter mixing capacity], a syrup composed of 1.425 kg of methyl methacrylate, 1.075 kg of neopentyl glycol dimethacrylate, and 2.625 kg of methyl methacrylate-based polymer beads as in Example 1; Was added, 6.85 kg of silane-treated aluminum hydroxide having a particle size of 8 μm was charged, the jacket temperature of the kneader was raised to 80 ° C., and the mixture was kneaded for 10 minutes to obtain a clay-like resin composition having a temperature of 83 ° C. This resin composition is
After cooling to 0 ° C., 50 g of 1,1-di-t-butylperoxy-3,3,5-trimethylcyclohexane was added and mixed for 3 minutes. 860 g of the obtained resin composition was put into a 250 mm × 200 mm flat mold, and subjected to pressure molding under a molding temperature of 130 ° C., a pressure resin pressure of 100 kgf / cm ² , and a pressure time of 12 minutes. 250
A flat plate of acrylic artificial marble of mm × 200 mm × 10 mm was obtained. The obtained molded article had no molding defects such as cracks, no discoloration (colorimetric value: b value 0.59), and had an extremely beautiful surface. When a 150 mm x 150 mm square sample was cut out and the falling ball impact strength was measured,
The molded article had a high falling ball impact strength of 3.4 J and was highly practical.

Example 3 Roll type pressure kneader [D-10 manufactured by Moriyama Seisakusho Co., Ltd.]
-20 type, 10 liters mixing capacity], 1.425 kg of methyl methacrylate, 1.075 kg of neopentyl glycol dimethacrylate and 2.625 kg of methyl methacrylate polymer beads as in Example 1 were charged, and the jacket temperature of the kneader was changed. Is heated to 80 ° C.
A syrup was prepared by kneading for 5 minutes. 6.85k of silane treated aluminum hydroxide having an average particle size of 8μ
g, and the temperature of the kneader jacket was heated to 80 ° C. and kneaded for 10 minutes to obtain a clay-like resin composition having a temperature of 84 ° C. After cooling this resin composition to 50 ° C.,
50 g of 1,1-di-t-butylperoxy-3,3,5-trimethylcyclohexane was added and mixed for 3 minutes. 860 g of the obtained resin composition was 250 mm × 200
into a flat plate mold having a thickness of 130 mm, a molding temperature of 130 ° C., a pressure of 100 kgf / cm ² , and a molding time of 12 minutes.
A 10 mm slab of acrylic artificial marble was obtained. The resulting molded article had no molding defects such as cracks, no discoloration (colorimetric value: b value 0.60), and had an extremely beautiful surface. When a 150 mm × 150 mm square sample was cut out and the falling ball impact strength was measured, it was a highly practical molded product having a high falling ball impact strength of 3.5 J.

Comparative Example 1 Roll type pressure kneader [D-10 manufactured by Moriyama Seisakusho Co., Ltd.]
-20 type, 10 liter mixing capacity], a syrup composed of 1.425 kg of methyl methacrylate, 1.075 kg of neopentyl glycol dimethacrylate, and 2.625 kg of methyl methacrylate polymer beads as in Example 1, and an average particle size Was charged with 6.85 kg of silane-treated aluminum hydroxide and 50 g of 1,1-di-t-butylperoxy-3,3,5-trimethylcyclohexane, which were kneaded at room temperature for 30 minutes. A clay-like resin composition having the same raw material composition was obtained. 860 g of the obtained resin composition was put into a flat plate mold having a size of 250 mm × 200 mm, and a molding temperature of 130 ° C. and a resin pressure of 100 kg were applied.
Pressure molding was performed under molding conditions of f / cm ² and a pressure time of 12 minutes to obtain a 250 mm × 200 mm × 10 mm acrylic artificial marble plate. The obtained molded product was slightly discolored to yellow and measured for color. As a result, the b value was as large as 1.49, and the appearance was poor. Also, when a 150 mm x 150 mm square sample was cut out and the falling ball impact strength was measured,
It was as low as 2.4J.

[0027]

As described above, the present invention is to provide a method for producing a resin composition suitable for hot press molding which has solved the conventional problems, whereby the falling ball impact strength is good and the discoloration is low. Thus, a molding material for acrylic artificial marble having good beauty, heat resistance, chemical resistance, weather resistance and the like can be easily produced and is useful.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Kazuhiko 2-28 Kurashiki-cho, Nakajo-cho, Kitakanbara-gun, Niigata Prefecture Inside Kuraray Co., Ltd.

Claims (3)

[Claims] 1. A syrup comprising 100 parts by weight of an unsaturated monomer mainly composed of (meth) acrylate and 50 to 400 parts by weight of a methyl methacrylate polymer, and 25 to 240 parts by weight based on 100 parts by weight of the syrup. A method for producing a resin composition, comprising: kneading a part of an inorganic filler at 65 to 120 ° C .; and mixing the obtained clay-like kneaded material with a curing agent after cooling or during the cooling process. 2. A syrup is produced by mixing and dissolving 50 to 400 parts by weight of a methyl methacrylate-based polymer in 100 parts by weight of an unsaturated monomer mainly composed of (meth) acrylic acid ester, and then 100 parts by weight of the syrup 25 to 2
The method for producing a resin composition according to claim 1, wherein 40 parts by weight of an inorganic filler is added and kneading is performed. 3. The unsaturated monomer mainly composed of (meth) acrylic ester is an unsaturated monomer containing 50% by weight or more of methyl methacrylate, and the inorganic filler is aluminum hydroxide. Item 3. The method for producing a resin composition according to item 1 or 2.