JPH10279764A - Method for producing resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a simple and efficient method for producing a resin composition, in which productivity is sufficiently improved, in particular, a method for producing the resin composition which can be used as a molding material for artificial marble. I do. SOLUTION: A monomer mainly composed of methacrylic acid ester, a methacrylic acid ester-based polymer and an inorganic filler are charged into a kneader to perform kneading, and the resin composition is discharged from the lower side of the kneader.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a resin composition, and more particularly to a method suitable for easily and inexpensively producing a resin composition which can be used for artificial marble. .

[0002]

2. Description of the Related Art Acrylic artificial marble is used for countertops, kitchen tops, vanities, flooring materials, wall materials, partition boards, etc., taking advantage of the excellent beauty and weather resistance of acrylic resin. It is used. As a method for producing this acrylic artificial marble, for example, Japanese Patent Publication No. 50-22
There is known a casting method as proposed in JP-A-586. Generally, the casting method involves pre-polymerizing methacrylic acid esters by about 10 to 30%, or mixing and mixing an inorganic filler into a so-called syrup in which a methacrylic acid ester polymer is dissolved in methacrylic acid esters. , After injecting the mixture into the gap in the mold,
This is a method of curing the mixture under normal pressure to obtain an artificial marble product. However, this casting method requires a long curing time and is low in productivity, and in addition to having a large amount of monomer components, giving off a monomer odor, and inconvenient handling due to stickiness caused by syrup at the time of injection. It is difficult to maintain a good working environment because it is easy to occur.

As one method for avoiding such a problem, for example, a press molding method as proposed in Japanese Patent Publication No. 5-13899 has been studied. In this method, a monomer containing 20% by weight or more of a polyfunctional (meth) acrylate as an essential component, a methacrylic resin powder, a curing agent, an inorganic filler, and the like are kneaded at room temperature or at a temperature lower than the curing temperature. The molding material obtained by aging is molded and cured by heating under pressure. However, according to this method, although a considerable improvement in productivity is achieved as compared with the conventional casting method or press molding method, mixing can be performed only at room temperature or at a temperature lower than the curing temperature because the curing agent is added and kneaded. For this reason, there is a problem that the aging step is required, the productivity is still low, and if the productivity is to be increased, the components cannot be sufficiently mixed.

[0004]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned problems and to provide a method for producing a resin composition in which productivity is sufficiently improved, and which is simple and efficient, in particular, molding for artificial marble. An object of the present invention is to provide a method for producing the resin composition that can be used as a material.

[0005]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors have conducted intensive studies on a method for producing a resin composition that can be used as a molding material for artificial marble, and as a result, added a curing agent. Without doing this, a monomer component, a polymer component, and an inorganic filler are kneaded in a kneader, and a kneaded material is discharged from the lower side of the kneader to stably obtain a clay-like resin composition suitable for press molding. Thus, the present invention has been completed. That is, the gist of the present invention is that a monomer mainly composed of methacrylic acid ester, a methacrylic acid ester-based polymer and an inorganic filler are charged into a kneader and kneaded, and the resin is mixed from the lower side of the kneader. A method for producing a resin composition, comprising discharging a composition.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The methacrylate-based monomer used in the present invention refers to a methacrylate alone or a monomer mixture of methacrylate-based monomer and another unsaturated monomer copolymerizable therewith. It is desirable that the content of methacrylic acid ester is 50% by weight or more, preferably 70% by weight or more.

[0007] Methacrylic acid esters include those having 5 carbon atoms.
Methacrylates of about 18 to 18 are preferably used, and specific examples include methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, lauryl methacrylate, and the like. . These are used alone or in combination of two or more. Among them, methyl methacrylate is particularly preferably used.

The other unsaturated monomer copolymerizable with the methacrylic acid ester is not particularly limited.
For example, acrylic esters such as methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, and lauryl acrylate; aromatic vinyl compounds such as styrene and α-methylstyrene; acrylonitrile, methacrylonitrile And unsaturated monomers such as acrylamide, vinyl acetate, vinyl chloride, acrylic acid, and methacrylic acid; and various monomers such as ethylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate, neopentyl glycol dimethacrylate, and trimethylolpropane trimethacrylate. Functional unsaturated monomers and the like. One or more of these monomers may be used.

As the methacrylate polymer used in the present invention, any methacrylate polymer which can be dissolved in the above-mentioned methacrylate-based monomer can be used without particular limitation. Preferable examples include those obtained by polymerizing a monomer mainly containing the methacrylic acid ester, or those obtained by polymerizing one or more of these monomers and other polymerizable monomers. it can.

As the methacrylic acid ester-based polymer, a polymer obtained by polymerizing the above-mentioned monomer mainly composed of methacrylic acid ester by an emulsion polymerization method, a suspension polymerization method, a bulk polymerization method or the like is usually used. The methacrylic acid ester-based polymer obtained by such a polymerization method is preferably in the form of particles from the viewpoint of mixing solubility with the monomer, and has a particle diameter of a size that can be used for kneading described below. Although it is not particularly limited as long as it is one, it is usually 5 mm or less, more preferably about 0.1 to 2 mm. The methacrylic acid ester is usually in the form of beads, pellets, pulverized powder, or the like, and is preferably in the form of beads from the viewpoint of solubility, handleability, and the like. The weight-average molecular weight of the methacrylate polymer is such that it can be dissolved in the monomer, and is usually in the range of 50,000 to 600,000, preferably 70 to 300,000, and more preferably 100 to 200,000. The mixing ratio of the methacrylic acid ester polymer is usually 50 to 4 with respect to 100 parts by weight of the monomer mainly composed of methacrylic acid ester.
00 parts by weight, preferably 80 to 300 parts by weight. Further, a part of the methacrylate polymer can be used in place of, for example, an acrylic partially crosslinked gel polymer whose production method is described in JP-A-60-202128.

Examples of the inorganic filler used in the present invention include aluminum hydroxide, magnesium hydroxide, alumina, magnesium oxide, calcium carbonate, silica, mica, glass beads and the like. There is no particular limitation unless it impairs. Among these inorganic fillers, aluminum hydroxide, magnesium hydroxide, silica, and glass beads are preferable, and aluminum hydroxide is particularly preferably used, from the viewpoints of high quality, stain resistance and processing performance of acrylic artificial marble. The particle size of the inorganic filler is usually 0.1 to 100 μm.
m is used, and more preferably 1 to 30 μm. Inorganic fillers that have been surface-treated, such as silane treatment, are also preferably used. The mixing ratio of the inorganic filler is usually 50 to 100 parts by weight of the monomer mainly composed of methacrylic acid ester.
500 parts by weight, preferably 100 to 400 parts by weight.

In the production method of the present invention, the raw materials used in the present invention are put into a kneading machine and kneaded to form a clay-like thickened resin composition, and the resin composition is discharged from the lower side of the kneading machine. It is characterized by the following. The kneading machine is not particularly limited as long as the resin composition can be mass-produced economically. For example, a continuous kneader such as a blade-type continuous kneader, a continuous paddle mixer, a continuous kneader, a single-screw extruder, and a twin-screw extruder can be used. Examples include a single-screw kneader and a continuous twin-screw kneader, and a continuous twin-screw kneader is particularly preferably used. As a continuous twin-screw kneader, raw materials are continuously fed into a kneading section by a feed screw section arranged in a raw material supply section, kneaded in a kneading section in which a rotor or a kneading desk or the like is arranged, and the kneaded material is continuously mixed. And a twin-screw extruder, a continuous kneader or the like is preferably employed. These continuous twin-screw kneaders are preferably those in which the kneading degree can be freely adjusted by changing the combination of a screw, a rotor, a kneading desk, and the like, and also correspond to a kneading part in terms of kneading properties. It is preferable that the L / D of the portion to be formed is about 4 to 50. The meshing of the two shafts of the continuous twin-screw kneader may be either a non-meshing type or a meshing type, and the rotation direction of the two shafts may be either a co-rotating type or a different-direction rotating type. The kneaded resin composition tends to be clogged at the discharge port or the backflow of the charged raw material from the charging port depending on the kneading conditions, each composition ratio of the kneaded material, etc. By discharging from the lower side of the machine, these problems can be prevented, and stable production becomes possible. In order to discharge the kneaded material from below, it is preferable to provide a discharge hole below the barrel of the continuous kneader, for example.

The kneading temperature is appropriately selected according to the composition of the kneaded material, but is preferably in the range of 65 to 120 ° C., particularly preferably 70 to 100 ° C., from the viewpoint of production rate. In order to knead at the above temperature, the continuous kneader usually has a temperature control section such as a jacket section, an electric heater,
It is preferable that the temperature of the kneading unit can be adjusted to a predetermined temperature by using steam, hot or cooling water, oil for adjusting temperature, or the like. 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.

A curing agent is added to and mixed with the resin composition produced by the method of the present invention for thermosetting. Generally, the resin composition obtained from the discharge port of the continuous kneader is cooled. After that, or during the cooling process, it is charged into the resin composition. When the length of the kneader to be used is long and the clay-like composition can be cooled in front of the discharge port, a hardening agent can be added to the cooling portion to be added and mixed.

The curing agent used in the method of the present invention is not particularly limited, and benzoyl peroxide, lauroyl peroxide, cumene hydroperoxide, bis (4-t-butylcyclohexyl) dicarbonate, which is usually used for radical polymerization, Organic peroxides such as 1,1-di-t-butylperoxy-3,3,5-trimethylcyclohexane; azobisisobutyronitrile, 2,2-
An azo compound such as azobis (2,4-dimethylvaleronitrile) is used. One or two of these curing agents may be used.
Used in more than species. The mixing ratio of the curing agent is based on 100 parts by weight of a monomer mainly composed of methacrylic acid ester.
Usually, it is 1 to 10 parts by weight, preferably 3 to 7 parts by weight.
When the curing agent is a solid, it is preferable to dissolve it in a small amount of monomer and to add it, because uniform mixing can be easily achieved.

Further, in the method of the present invention, in order to improve the toughness and strength of the molded product obtained in the present invention and to exhibit a reinforcing effect such as suppression of the generation and progress of cracks, the molded product is reinforced during kneading or mixing. Single fibers can be added. The selected fibers include inorganic fibers such as asbestos and glass fibers, various organic fibers including aramid fibers and vinylon fibers, carbon fibers, and metal whiskers. Since the combination and the amount of the reinforcing monofilament used vary depending on the characteristics of the desired molded product, it is not possible to strictly define them, but, for example, the purpose is to improve toughness and suppress cracking. When using chopped strands of vinylon fiber convergent type, as the fiber shape, fiber diameter 5-300μ
m, the fiber length is preferably in the range of 3 to 50 mm,
The addition amount is preferably in the range of 5 to 200 parts by weight based on 100 parts by weight of the monomer mainly composed of methacrylate ester used in the present invention. The amount of monomer 100 mainly composed of methacrylic acid ester
If the amount is less than 5 parts by weight, it is difficult to exert the reinforcing effect. Kneading becomes extremely difficult.

In the method of the present invention, various kinds of pattern materials, coloring agents, coupling agents, light stabilizers,
Additives such as antioxidants, release agents, polymerization regulators, and defoamers can be used in combination. Further, the mixing in the present invention,
In order to improve the rate of thickening in the kneading step and to improve the transferability to a mold when a molded article is manufactured from the resin composition, a resin mainly composed of (meth) acrylate used in the present invention is used. A resin composition which is insoluble in a saturated monomer and has a degree of swelling can also be added.

The resin composition obtained by the method of the present invention can be shaped 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, usually, a molding pressure of 10 to 200 kg / cm ² , a molding temperature of 80 to 180 ° C.,
The molding time is about 10 minutes.

[0019]

The present invention will be described below in more detail with reference to examples. The examples show one embodiment of the present invention, and the present invention is not limited to these examples.

Example 1 A continuous kneader provided with a discharge hole on the lower side of a barrel [S2 type KRC kneader, manufactured by Kurimoto Iron Works Co., Ltd., diameter 5
0φ, L / D = 13, rotation speed 100 rpm, power 3.7
kw], a liquid obtained by mixing 57 parts by weight of methyl methacrylate with 43 parts by weight of neopentyl glycol dimethacrylate is supplied from a liquid mixing tank at a feed rate of 10 kg / hour by a quantitative pump, and further treated with silane having an average particle size of 8 μm. 274 parts by weight of aluminum hydroxide and methacrylic resin beads [PARAPET HR, manufactured by Kuraray Co., Ltd .: a copolymer of 8% by weight of methyl methacrylate and 2% by weight of methyl acrylate, a weight average molecular weight of 110,000, and an average particle diameter of 0.1%. 3
mm] of powder mixed with 105 parts by weight and 47 parts by weight of the stone-grain pattern material by a powder quantitative feeder to obtain 42.6 kg /
It was supplied at a feed rate over time. A heating medium at 90 ° C. was passed through the jacket of the continuous kneader and heated. The clay-like resin composition at a temperature of 82 ° C. was stably and continuously discharged from the discharge port for 6 hours. After cooling the resin composition to 50 ° C., 13 kg of the resin composition and 50 g of 1,1-di-tert-butylperoxy-3,3,5-trimethylcyclohexane were rolled into a pressure kneader [Moriyama Seisakusho Co., Ltd. D-10-2
No. 0, mixing volume 10 liter]. 10 kg of the obtained resin composition is weighed at 600 mm × 1000 on the top plate.
mm, into a vanity mold having a 50 mm high hang and back guard, and a molding temperature of 130 ° C.
Pressure molding is performed under a molding condition of a pressure resin pressure of 100 kgf / cm ² and a pressure time of 12 minutes, and 600 mm × 1000
A mm × 10 mm acrylic artificial marble vanity was obtained. The obtained molded article had no molding defects such as cracks and had an extremely beautiful surface.

Example 2 A liquid obtained by mixing 57 parts by weight of methyl methacrylate and 43 parts by weight of neopentyl glycol dimethacrylate in a continuous kneader similar to that in Example 1 was fed from a liquid mixing tank at a rate of 10 kg / hour by a metering pump. Supply in quantity,
Further, a powder obtained by mixing 274 parts by weight of silane-treated aluminum hydroxide having an average particle diameter of 8 μm and 105 parts by weight of methacrylic resin beads as in Example 1 was fed at a feed rate of 37.9 kg / hour by a powder quantitative feeder. Supplied.
The mixture was heated by passing a heating medium at 90 ° C. through the jacket of the continuous kneader. The clay-like resin composition at a temperature of 80 ° C. was stably and continuously discharged from the discharge port even after 6 hours.
After cooling this resin composition to 50 ° C., 13 kg
And 55 g of 1,1-di-t-butylperoxy-3,3,5-trimethylcyclohexane were mixed in the same roll-type pressure kneader as in Example 1 for 3 minutes. 10 kg of the obtained resin composition is weighed at 600 mm × 1000 mm, 50 m
m into a vanity mold having a hanging height and a back guard with a height of m
Pressure molding was performed under molding conditions of 00 kgf / cm ² and a pressure time of 12 minutes, and 600 mm × 1000 mm × 10 m
m acrylic artificial marble vanity. The obtained molded article had no molding defects such as cracks and had an extremely beautiful surface.

Example 3 A liquid obtained by mixing 68 parts by weight of methyl methacrylate and 32 parts by weight of neopentyl glycol dimethacrylate in a continuous kneader similar to that of Example 1 was supplied from a liquid mixing tank at a rate of 10.6 kg / hour by a metering pump. Of 212 parts by weight of silane-treated aluminum hydroxide having an average particle size of 81, 70 parts by weight of methacrylic resin beads as in Example 1, 47 parts by weight of stone-like pattern material, and reinforcement. Fiber for use [made by Kuraray Co., Ltd .: RF-S60]
2] A powder mixed with 19 parts by weight was supplied by a powder quantitative feeder at a feed rate of 39.4 kg / hour. The mixture was heated by passing a heating medium at 90 ° C. through the jacket of the continuous kneader. The clay-like resin composition at a temperature of 80 ° C. was stably and continuously discharged from the discharge port even after 6 hours. After cooling the resin composition to 50 ° C., 13 kg thereof and 82 g of 1,1-di-tert-butylperoxy-3,3,5-trimethylcyclohexane were mixed for 3 minutes in the same pressure kneader as in Example 1. did. 10 kg of the obtained resin composition
Into a mold for a vanity table having a top plate part of 600 mm × 1000 mm and a height of 50 mm and a front guard and a back guard, and a molding temperature of 130 ° C. and a pressure of 110 kgf.
Pressure molding was performed under the molding conditions of 12 cm / cm ² and a pressure of 12 minutes to obtain a molded product for a washbasin with a size of 600 mm × 1000 mm × 11 mm. No molding defects such as cracks were observed on the surface of the obtained molded product, and the product was extremely beautiful and had high commercial value.

Comparative Example 1 In the method of Example 1, the continuous kneader (diameter: 50φ, L / D = 13, rotation speed: 100 rpm) was changed to a type in which the discharge port was laterally attached to the tip of the screw shaft, and the resin composition was changed. When the production of the product was continued, the discharge from the discharge port became temporarily defective after a lapse of 15 minutes, and the backflow phenomenon of the raw material occurred at the raw material input port, so that it was difficult to continue the operation stably. .

[0024]

According to the method of the present invention, a method of completing the kneading of a resin composition from a monomer component, a polymer component and an inorganic filler at a stroke by using a kneading machine, with the discharge port of the kneading machine being on the lower side. In addition, since a resin composition can be stably produced for a long time without clogging of raw materials, it is suitable as a method for easily and inexpensively mass-producing molding materials for artificial marble and the like.

 ────────────────────────────────────────────────── ─── 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 kneader in which a monomer mainly composed of methacrylic acid ester, a methacrylic acid ester-based polymer and an inorganic filler are charged and kneaded, and the resin composition is discharged from the lower side of the kneader. A method for producing a resin composition, comprising: 2. The resin composition according to claim 1, wherein a monomer mainly composed of methacrylate, a methacrylate polymer, an inorganic filler and a reinforcing single fiber are charged and kneaded. Manufacturing method of goods. 3. The method for producing a resin composition according to claim 1, wherein the kneading is performed at 65 to 120 ° C.