JPH10218910A - Production of resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a resin composition useful as a material for especially, artificial marble simply and efficiently in high productivity by kneading a mixture prepared by kneading a monomer based on a methacrylic ester, a methacrylic ester polymer and an inorganic filler in a specified temperature range and a monomer based on methacrylic ester. SOLUTION: The monomer used is a methacrylic ester itself or a mixture comprising a major proportion of a methacrylic ester and other unsaturated monomers copolymerizable therewith and having a methacrylic ester content of 70wt.% or above. The methacrylic ester used is at least one 5-18 deg.C methacrylic ester (e.g. methyl methacrylate). The unsaturated monomer copolymerizable with the methacrylic ester means e.g. a polyfunctional unsaturated monomer such as an acrylic ester or an aromatic vinyl compound. The methacrylic ester polymer used is one prepared by polymerizing a monomer based on a methacrylic ester. The inorganic filler used is aluminum hydroxide.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing a resin composition, and more particularly to a method for producing a high-quality resin composition which can be used as artificial marble simply and inexpensively without requiring an aging step. It relates to a method suitable for production.

[0002]

2. Description of the Related Art Acrylic artificial marble in which an acrylic resin is filled with an inorganic filler is used for kitchen tops, various counter tops, vanities, shower trays, flooring, and wall materials, utilizing its beautiful appearance and excellent characteristics. Widely used for partition boards. As a method for producing this acrylic artificial marble, for example, a cast molding method proposed in Japanese Patent Publication No. 50-22586 is known. In general, the casting method involves the addition of methacrylates to 10 to 3
About 0% is pre-polymerized, or a methacrylic acid ester polymer is dissolved in methacrylic acid esters, so-called syrup is blended with an inorganic filler, and the mixture is injected into a gap in a mold. This is a method of curing the mixture under normal pressure to obtain an artificial marble product. However, adjustment of the syrup cannot be performed easily, which is a cause of a decrease in productivity of the casting method. That is, in the method of pre-polymerizing methacrylic acid esters, equipment and steps for pre-polymerization are required, and it is essentially difficult to adjust the polymerization rate because the polymerization is stopped in the middle of the method. It is difficult to easily produce syrup with good reproducibility. Further, the method of dissolving a methacrylate polymer in methacrylates has a problem that it takes a long time to dissolve.

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 which is an essential component, a methacrylic acid-based resin powder, an inorganic filler, a curing agent, 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. In addition, there is a problem that the productivity is still low because the aging step is required, and the components cannot be sufficiently mixed in order to increase the productivity.

[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 problems, the present inventors have conducted intensive studies on a method for producing a resin composition that can be used as a molding material suitable for artificial marble. By kneading the main components of the composition at a high temperature, and then further mixing and kneading the obtained kneaded product with the monomer, a slurry-like molding material suitable for the casting molding method or suitable for the press molding method The present inventors have found that a clay-like molding material having shape stability can be easily produced, and have completed the present invention.

That is, the gist of the present invention is as follows.
A monomer mainly composed of methacrylic acid ester, a methacrylic acid ester-based polymer and an inorganic filler are used at 65 to 120 ° C.
And a second step of kneading the kneaded product obtained in the first step and a monomer mainly composed of methacrylic acid ester.

[0007]

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.

[0008] 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.

The methacrylic acid ester polymer used in the present invention can be used without particular limitation as long as it is a methacrylic acid ester polymer which is soluble in the above-mentioned monomer mainly composed of methacrylic acid ester. Preferred examples include those obtained by polymerizing the above-mentioned methacrylic acid ester-based monomers, or those obtained by polymerizing one or more of these monomers and other polymerizable monomers. be able to.

The methacrylic acid ester-based polymer used in the present invention is usually 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. 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. Is not particularly limited as long as it is usually 5 mm
Hereinafter, it is more preferably about 0.1 to 2 mm. The shape of the methacrylate polymer is usually in the form of beads, pellets, pulverized powder, and the like.
It is preferably in the form of beads from the viewpoint of handleability and the like. The weight-average molecular weight of the methacrylate polymer is selected from those which can be dissolved in the monomer, and is usually 5 to 60.
10,000, preferably 70,000 to 300,000, more preferably 10 to 20
Range of ten thousand.

In the first step, the mixing ratio of the monomer mainly composed of methacrylate to the methacrylic ester based polymer is usually 50 to 50 parts by weight based on 100 parts by weight of monomer mainly composed of methacrylic ester. 600 parts by weight of a methacrylate polymer is used, preferably 70 parts by weight.
~ 400 parts by weight are used. Further, a part of the methacrylic acid ester-based polymer is, for example, disclosed in JP-A-60-20212.
No. 8 can also be used in place of the acrylic partially cross-linked gel polymer whose production method is described.

Examples of the inorganic filler used in the present invention include fine powders such as aluminum hydroxide, magnesium hydroxide, alumina, magnesium oxide, calcium carbonate, silica, mica, and glass beads. There is no particular limitation unless the appearance of the product is impaired. Among these inorganic fillers, aluminum hydroxide, magnesium hydroxide, silica, and glass beads are preferable, and aluminum hydroxide is particularly preferable, from the viewpoint of luxury, stain resistance, and processing performance as an acrylic artificial marble product. Used. The particle size of the inorganic filler is usually 0.1 to 100 μm, more preferably 1 to 30 μm.

In the first step, the mixing ratio of the monomer mainly composed of methacrylate and the inorganic filler is usually 50 to 700 parts by weight based on 100 parts by weight of monomer mainly composed of methacrylate. Inorganic filler is used,
Preferably, 100 to 500 parts by weight are used.

In the method of the present invention, kneading is carried out in the first step by reducing the proportion of the monomer mainly composed of methacrylic acid ester from the target resin composition composition, and then in the second step, the mixture is obtained in the first step. Characterized by kneading the remaining kneaded material and the remaining amount of the monomer mainly composed of methacrylic acid ester, thereby efficiently kneading, it is possible to efficiently produce a resin composition of a desired composition in a short time. It becomes possible.

First, in the first step, the kneading temperature is set at 6
A range of 5 to 120 ° C is used, preferably 70 to 10 ° C.
0 ° C. If the temperature is lower than 65 ° C., the dissolution of the polymer will be slow, resulting in poor productivity. On the other hand, if the temperature is higher than 120 ° C., the polymerization of the monomer and the decomposition of the polymer are liable 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. As the kneading machine, for example, a batch type twin screw kneader or a continuous type twin screw kneader is preferably used. As a batch type twin-screw kneader, for example, a Z-type, an H-type, a finish-tail type placed in parallel in a trough,
A twin-arm kneader in which two mixing blades, such as a dispersion type, rotate in opposite directions to shear, compress, stretch and knead the mixture; a double-arm kneader equipped with a mechanical pressure cover A pressure kneader in which the kneading material is compressed by air pressure, liquid pressure or the like to generate a strong shearing force between the kneaded material and the trough wall surface or between the kneaded materials to enhance the kneading;
Raw materials are charged into a closed mixing chamber, and 2
An internal mixer or the like is used in which the book rotors rotate in opposite directions to give a strong shearing force between the chamber wall and the rotor or between the rotors to knead them. As a continuous twin-screw kneader, the raw materials are continuously fed to the kneading unit by the feed screw unit arranged in the raw material supply unit,
Kneading is performed in a kneading section provided with a rotor or a kneading desk and the like, and the kneaded material is continuously discharged. A twin-screw kneader, a continuous kneader, or the like is preferably used.

The kneading time in the first step varies depending on the type of kneader to be used, the number of revolutions and the kneading temperature.
Minutes to about 10 minutes are employed. The kneading temperature in the subsequent second step is not particularly limited as long as polymerization of the monomer and decomposition of the polymer do not occur, but is preferably 90 ° C or lower, particularly preferably 80 ° C or lower. As the kneading method in the second step, the same method as in the first step can be adopted. The kneading time in the second step varies depending on the type of kneader, the number of revolutions and the kneading temperature, but is generally about 0.5 to 5 minutes. The present invention can also be realized by, for example, dividing and using a continuous kneader to continuously perform the first step on the upstream side and the second step on the downstream side.

In the present invention, by appropriately adjusting the amount of the monomer added in the second step, a monomer corresponding to 50 to 200% of the amount of the monomer used in the first step is preferably added. By adding in two steps, it is possible to produce a resin composition having properties generally in the range of slurry to clay and having substantially no change in viscosity. "Substantially no change in viscosity" means that there is no change in viscosity within 24 hours or almost no change within 5%, and the evaluation is made by a BL viscometer, pressure spreadability and the like. The change in viscosity due to the change over time occurs because the methacrylate polymer remains undissolved. If there is a change in the viscosity, the suitable molding conditions are not constant, and the molded product tends to have poor appearance, which is not preferable.

A curing agent is usually added to the resin composition produced by the production method of the present invention for thermosetting. Generally, the resin composition is introduced into the resin composition after cooling or during the cooling process. A curing agent may be mixed in the third step. However, when the kneading temperature in the second step is lower than the curing temperature of the curing agent, the unsaturated monomer mainly composed of (meth) acrylic acid ester may be used. A curing agent can be added and kneaded together with the remaining amount of the body.

As the curing agent, an azobis compound or an organic peroxide, which is a radical polymerization initiator, is usually used. For example, azobisisobutyronitrile, benzoyl peroxide, t-butyl peroxide, cumene hydroxy peroxide, t One or more of -butyl hydroperoxide, dicumyl peroxide, 1,1-di-t-butylperoxy-3,3,5-trimethylcyclohexane and the like can be used. The amount of the curing agent used is 0.1 part by weight based on 100 parts by weight of the total amount of the monomer mainly composed of methacrylate used in the first step and the monomer mainly composed of methacrylate used in the second step. 001 to 10 parts by weight,
Preferably, it is used in a proportion of 0.05 to 7 parts by weight. 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.

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

The slurry-like resin composition produced by the method of the present invention is suitably used for casting. For the clay-like resin composition, methods such as compression molding, injection molding, and extrusion molding can be suitably used. By shaping and curing by these methods, a molded product, in particular, a marble-like product can be obtained. As the molding conditions of the compression molding, usually, the molding pressure is 10 to 200 kg / cm ² and the molding temperature is 80 to 18
0 ° C., molding time is about 10 minutes.

[0024]

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 pressure spreadability and viscosity were measured and evaluated by the following methods.

(Measurement of Extensibility under Pressure)
0 g is weighed and heated by a press machine heated to a hot platen temperature of 50 ° C.
Upper heating plate / 50 μm thick nylon film / resin composition /
In a configuration of a 50 μm thick nylon film / lower heating plate, pressure is applied for 60 seconds with a load of 3 tons, and the spread area of the resin composition is measured using an area meter [Hayashi Denko Co., Ltd .: Automatic area meter AAM-8 type]. Measure. (Evaluation of pressurization spreadability) By the above-mentioned method, spread by pressurizing and heating immediately after kneading the resin composition and leaving the resin composition in a nylon film bag having a thickness of 50 μm for about 1 day at room temperature. The area (pressure spreadability) was measured, and it was evaluated whether or not the obtained resin composition had a change in viscosity due to standing at room temperature for one day (if no change was observed, it was evaluated that aging was unnecessary). Further, the film-shaped resin composition stretched between the nylon films was visually observed, and the presence or absence of the undissolved polymer was examined.

(Measurement of Viscosity of Slurry Resin Composition) BL
It was measured by a viscometer (manufactured by Tokyo Keiki Co., Ltd.). (Evaluation of viscosity of slurry-like resin composition)
Immediately after kneading the resin composition, put the resin composition in a polyethylene container, measure the viscosity after leaving it at room temperature for about 1 day in a sealed state with a nylon film having a thickness of 50 μm as a lid, and add 1 to the obtained resin composition. It was evaluated whether there was a change in viscosity due to standing at room temperature for a day (if no change was observed, it was evaluated that aging was not necessary).

Example 1 Continuous twin-screw kneader [S2 type KRC manufactured by Kurimoto Iron Works Co., Ltd.]
Kneader, caliber 50φ, L / D = 13, rotation speed 100r
pm, power 3.7 kW], a copolymer of 90.3 parts by weight of silane-treated aluminum hydroxide having an average particle size of 8 μm and methacrylic resin beads [98% by weight of methyl methacrylate and 2% by weight of methyl acrylate, Weight average molecular weight 110
000, average particle diameter 0.3 mm], a mixture of 9.7 parts by weight was supplied at a feed rate of 48.6 kg / hour, and 16 parts by weight of neopentyl glycol dimethacrylate was added to 84 parts by weight of methyl methacrylate in a liquid mixing tank. The mixed liquid was supplied from a liquid mixing tank by a metering pump at a feed rate of 4.0 kg / hour and kneaded. The jacket of the kneader was heated with a heating medium at 90 ° C.
After cooling the kneaded material at a temperature of 50 ° C. to 50 ° C., 13.5 kg of the kneaded material obtained, 3.8 kg of a liquid obtained by mixing 84 parts by weight of methyl methacrylate with 16 parts by weight of neopentyl glycol dimethacrylate, and azobisisopropane Butyronitrile 4
g into a roll type pressure kneader [Moriyama Seisakusho Co., Ltd., D-
10-20 type, mixing volume 10 liter] and kneaded and mixed at room temperature for 10 minutes. The resulting resin composition was in the form of a slurry, had a viscosity of 145 poise at 25 ° C.
After 4 hours, there was no change in viscosity. Next, 270 g of the resin composition thus obtained was added to 250 mm × 200 mm ×
It is poured into a casting mold having a size of 3 mm and heated at 60 ° C. for 2 hours and further at 120 ° C. for 1 hour to obtain 250 mm × 20 mm.
A flat acrylic artificial marble of 0 mm × 3 mm was obtained. The obtained molded product had no molding defects such as cracks, had an extremely beautiful surface, and was of high commercial value.

Example 2 Continuous twin-screw kneader [S2 type KRC manufactured by Kurimoto Iron Works Co., Ltd.]
Kneader, caliber 50φ, L / D = 13, rotation speed 100r
pm, power 3.7 kW], and 80.4 parts by weight of silane-treated aluminum hydroxide having an average particle size of 8 μm.
A mixture of 19.6 parts by weight of methacrylic resin beads similar to the above was supplied at a feed rate of 46.5 kg / hour, and a liquid obtained by mixing 84 parts by weight of methyl methacrylate and 16 parts by weight of neopentyl glycol dimethacrylate in a liquid mixing tank. Was supplied from the liquid mixing tank at a feed rate of 6.0 kg / hour by a metering pump, and kneaded while heating the jacket of the kneader with a heating medium at 90 ° C. The kneaded product at a temperature of 81 ° C. obtained from the discharge port was continuously supplied to a tandem extruder through a jacket with cooling water, and 84 parts by weight of methyl methacrylate was added.
A solution obtained by mixing 16 parts by weight of neopentyl glycol dimethacrylate was supplied at a feed rate of 5.0 kg / hour, kneaded and cooled to 50 ° C. in one stage, and then 1,
1-Di-t-butylperoxy-3,3,5-trimethylcyclohexane was fed at a feed rate of 0.2 kg / hour and kneaded to obtain a clay-like resin composition at 40 ° C. The pressure spreadability of the obtained resin composition was 302 cm ² ,
There was no change after 4 hours. Next, 270 g of the resin composition thus obtained was poured into a flat plate mold having a size of 250 mm × 200 mm, and a molding temperature of 130 ° C. and a pressure of 60 ° C.
250 m under molding conditions of kgf / cm ² and molding time of 6 minutes
A flat acrylic artificial marble of mx 200 mm x 3 mm was obtained. The obtained molded product had no molding defects such as cracks, had an extremely beautiful surface, and was of high commercial value.

[0029]

The present invention can provide a slurry-like molding material suitable for the cast molding method or a clay-like molding material suitable for the press molding method, and is a simple and inexpensive method for producing a molding material for artificial marble. It is suitable.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08K 3/22 C08K 3/22 C08L 33/06 C08L 33/06 // (C04B 26/06 14:36 16:04) 111: 54 (72) Inventor Kazuhiko Ma No. 2-28 Kurashiki-cho, Nakajo-cho, Kitakanbara-gun, Niigata Pref.

Claims (2)

[Claims] 1. A first step of kneading a monomer mainly composed of methacrylic acid ester, a methacrylic ester polymer and an inorganic filler at 65 to 120 ° C., and a kneaded product obtained in the first step and methacrylic acid. A method for producing a resin composition, comprising: a second step of kneading a monomer mainly containing an acid ester. 2. The method according to claim 1, wherein the resin composition is a slurry or a clay.