JP3657383B2 - Method for producing resin composition - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a resin composition. More specifically, the present invention is suitable for producing a resin composition that can be used as a molding material for artificial marble and the like easily and inexpensively without requiring an aging step. It is about the method.
[0002]
[Prior art]
Acrylic artificial marble filled with inorganic fillers in acrylic resin makes the most of its beautiful appearance and excellent characteristics, and is widely used in kitchen top plates, various countertops, vanity tops, shower trays, flooring materials, wall materials, partition plates, etc. It's being used.
As a method for producing this acrylic artificial marble, for example, a cast molding method as proposed in Japanese Patent Publication No. 50-22586 is known. In general, the cast molding method involves prepolymerizing about 10 to 30% of methacrylic acid esters, or mixing and mixing an inorganic filler in so-called syrup in which a methacrylic acid ester polymer is dissolved in methacrylic acid esters. In this method, the mixture is poured into a gap in the mold, and then the mixture is cured under normal pressure to obtain an artificial marble product. However, there is no simple method for adjusting the syrup, which causes the productivity of the casting method to be lowered. That is, in the method for prepolymerizing methacrylic acid esters, equipment and steps for prepolymerization are necessary, and since the polymerization is stopped in the middle, it is essentially difficult to adjust the polymerization rate, and a constant polymer concentration is required. There is a problem that it is difficult to easily manufacture syrup with high reproducibility. In addition, the method of dissolving a methacrylic ester polymer in methacrylic esters has a problem that it takes a long time to dissolve.
[0003]
As one method for avoiding such problems, for example, a press forming 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 an essential component polyfunctional (meth) acrylate, a methacrylic acid resin powder, a curing agent, an inorganic filler and the like are kneaded at a normal temperature or a temperature lower than the curing temperature. A molding material obtained by aging is heated under pressure to be molded and cured. However, according to this method, although productivity can be improved considerably as compared with the conventional cast molding method and press molding method, since the kneading agent is added and kneaded, it can be mixed only at room temperature or a temperature lower than the curing temperature. In addition, since an aging step is required for this reason, productivity is still low, and when trying to improve productivity, the components cannot be sufficiently mixed, and when trying to mix sufficiently, the resin composition is colored. There were problems such as.
[0004]
[Problems to be solved by the invention]
Therefore, the object of the present invention is to solve the above-mentioned problems, the productivity is sufficiently improved, and a simple and efficient method for producing a resin composition, particularly a molding material for artificial marble. It is providing the manufacturing method of a resin composition.
[0005]
[Means for Solving the Problems]
In order to solve the above problems, the present inventors have intensively studied a method for producing a resin composition that can be used as a molding material for artificial marble and the like. As a result, resin composition components excluding a premixed curing agent have been obtained. Found that by kneading under high temperature, it is possible to easily produce a slurry-like molding material suitable for the casting method or a clay-like molding material having shape stability suitable for the press molding method, and completed the present invention. did.
[0006]
That is, the gist of the present invention is that (A) a monomer mainly composed of methacrylic acid ester, a methacrylic acid ester polymer and an inorganic filler are mixed, and the methacrylic acid ester polymer is mixed with methacrylic acid ester. A first step of absorbing the main monomer, (B) a second step of kneading the mixture obtained in the first step at 65-120 ° C., and (C) a slurry or clay obtained in the second step It is a manufacturing method of the resin composition comprised from the 3rd process of mixing a hardening | curing agent after cooling to a kneaded material in the cooling process.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
The monomer mainly composed of methacrylic acid ester used in the present invention refers to a monomer mixture of methacrylic acid ester alone or other unsaturated monomer mainly composed of methacrylic acid ester and copolymerizable therewith. The methacrylic acid ester is 50% by weight or more, preferably 70% by weight or more.
[0008]
As the methacrylic acid ester, a methacrylic acid ester having about 5 to 18 carbon atoms is preferably used. Specifically, for example, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, methacrylic acid. Examples include cyclohexyl and lauryl methacrylate. These may be used alone or in combination of two or more. Among them, methyl methacrylate is particularly preferably used.
[0009]
The other unsaturated monomer copolymerizable with the methacrylic acid ester is not particularly limited. For example, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, Acrylic esters such as lauryl acrylate; aromatic vinyl compounds such as styrene and α-methylstyrene; unsaturated monomers such as acrylonitrile, methacrylonitrile, acrylamide, vinyl acetate, vinyl chloride, acrylic acid, methacrylic acid; ethylene Examples thereof include polyfunctional unsaturated monomers such as glycol dimethacrylate, 1,3-butylene glycol dimethacrylate, neopentyl glycol dimethacrylate, and trimethylolpropane trimethacrylate. These monomers are used alone or in combination of two or more.
[0010]
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 that dissolves in the monomer mainly composed of the above methacrylic acid ester. Preferable examples include those obtained by polymerizing monomers mainly composed of esters, or those obtained by polymerizing one or more of these monomers with other polymerizable monomers.
[0011]
As the methacrylic acid ester polymer, a polymer obtained by polymerizing a monomer mainly composed of the above 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 the particle size is such that it can be used for kneading described later. Although it will not specifically limit if it is a thing, Usually, it is 5 mm or less, More preferably, it is about 0.1-2 mm. The shape of the methacrylic acid ester is usually a bead shape, a pellet shape, a pulverized powder particle shape, and the like, and is preferably a bead shape from the viewpoints of solubility and handleability. The weight-average molecular weight of the methacrylic acid ester polymer is such that it can be dissolved in the monomer, and is usually in the range of 5 to 600,000, preferably 70 to 300,000, more preferably 70 to 200,000. The blending ratio of the methacrylic ester polymer is usually 10 to 400 parts by weight, preferably 20 to 300 parts by weight with respect to 100 parts by weight of the monomer mainly composed of methacrylic ester.
Further, a part of the methacrylic acid ester polymer can be used instead of the acrylic partially crosslinked gel polymer whose production method is described in, for example, JP-A-60-202128.
[0012]
Examples of the inorganic filler used in the present invention include aluminum hydroxide, magnesium hydroxide, alumina, magnesium oxide, calcium carbonate, silica, mica, and glass beads. However, the addition of the inorganic filler deteriorates the appearance of the molded product. If not, there is no particular restriction. Among these inorganic fillers, aluminum hydroxide, magnesium hydroxide, silica, and glass beads are preferable from the viewpoint of high-grade feeling required for acrylic artificial marble products, contamination resistance, and processing performance, and particularly aluminum hydroxide. Is preferably used. The particle size of the inorganic filler is usually 0.1 to 100 μm, more preferably 1 to 30 μm. A surface-treated inorganic filler such as silane treatment is also preferably used. The blending ratio of the inorganic filler is usually 50 to 500 parts by weight, preferably 100 to 400 parts by weight with respect to 100 parts by weight of the monomer mainly composed of methacrylic acid ester.
[0013]
In the method of the present invention, first, (A) a monomer mainly composed of a methacrylic ester, a methacrylic ester polymer and an inorganic filler are mixed in the first step, and a monomer mainly composed of a methacrylic ester is obtained. Absorb to methacrylic acid ester polymer. The method of mixing and absorbing is not particularly limited as long as excessive shearing or the like that causes coloring or polymerization is not applied, but for example, stirring in a mixing tank at room temperature or mixing in a kneader Such a method is preferably employed, but can be left after this. The mixing and absorption time varies depending on the method and conditions, but is usually 1 minute or more, preferably about 2 to 40 minutes, and is easily dissolved and homogenized when kneaded in the second step. . By providing the first step, kneading in the second step is facilitated, and excessive kneading that causes coloring and polymerization can be prevented. In the first step, a part of the methacrylic ester polymer is dissolved in the unsaturated monomer mainly composed of (meth) acrylic ester, but the kneading in the second step is easy and efficient due to the increased viscosity. It is preferable.
[0014]
Subsequently, in (B) 2nd process, the mixture obtained at the 1st process is knead | mixed in the range of 65-120 degreeC, Preferably it knead | mixes at 70-100 degreeC. If the temperature is less than 65 ° C., the dissolution rate of the resin is slow and the production is not efficient. On the other hand, kneading at a temperature exceeding 120 ° C. is liable to cause polymerization of the monomer, decomposition of the polymer, and the like. In order to knead at the above temperature, the kneader used for kneading usually has a temperature control part such as a jacket part, and the kneading part is predetermined using an electric heater, steam, hot water or cooling water, temperature control oil, etc. It is preferable that the temperature can be adjusted to the following temperature.
[0015]
The kneading method is not particularly limited as long as the effects of the present invention can be realized, and as the kneader, a batch type biaxial kneader, a continuous biaxial kneader, or the like is preferably used.
[0016]
As a batch type twin-screw kneader, for example, two mixing blades such as Z type, H type, finish tail type, and dispersion type placed in parallel in the trough rotate in opposite directions, Double-arm kneader that kneads by shearing, compressing and stretching; equipped with a mechanical pressure cover on the double-arm kneader and compressing the pressure cover with air pressure, hydraulic pressure, etc. Pressurized kneader that generates strong shearing force between them and strengthens kneading; feeds raw material into a sealed mixing chamber, the two rotors built in the mixing chamber rotate in opposite directions, and the chamber wall and rotor Examples thereof include an internal mixer that kneads by applying a strong shearing force between the rotors or between the rotors.
[0017]
In addition, as a continuous twin-screw kneader, raw materials are continuously fed to a kneading unit by a feed screw unit arranged in a raw material supply unit, and kneaded in a kneading unit in which a rotor or a needing desk is arranged, and then in a slurry or clay As long as the kneaded material is continuously discharged, a twin screw kneader, a container kneader, or the like is preferably employed.
The kneading time in the second step varies depending on the type of kneader, the rotational speed, the kneading temperature, etc., but generally a time of about 2 to 10 minutes is employed.
[0018]
In the present invention, for example, by using a continuous kneader separately, the first step can be continuously performed on the upstream side, and the second step can be continuously performed on the downstream side. Further, the curing agent can be used at a temperature lower than the curing temperature. It can also be added and mixed in the final step.
[0019]
Furthermore, as a (C) 3rd process, a cooling agent is thrown into and mixed with the slurry-like or clay-like kneaded material obtained at the 2nd process after cooling or in the cooling process. As the curing agent to be used, 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 usually 0.001 to 10 parts by weight, preferably 0.05 to 7 parts by weight, based on 100 parts by weight of the total amount of monomers mainly composed of methacrylic acid esters. . When the curing agent is a solid, it is preferable to dissolve it in a small amount of monomer and add it easily and uniformly.
[0020]
According to the present invention, it is possible to produce a resin composition having properties ranging from slurry to clay, no coloration, and 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 it is evaluated by a BL type viscometer, pressure spreadability, etc. The Viscosity change is a phenomenon that occurs when methacrylic acid ester polymer remains undissolved. If there is a viscosity change, suitable molding conditions are not constant, and the molded product also has a poor appearance. Cheap.
[0021]
In the method of the present invention, fiber materials such as glass fibers, aramid fibers, and carbon fibers, various pattern materials, colorants, cups, etc., as necessary, at the time of kneading or mixing, as long as the object of the present invention is not hindered. Additives such as a ring agent, light stabilizer, antioxidant, mold release agent, polymerization regulator, and defoaming agent can be used in combination.
[0022]
The slurry-like resin composition produced by the method of the present invention is suitably used for cast molding. A viscous resin composition 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. The molding conditions during compression molding are usually a molding pressure of 10 to 200 kg / cm ² , a molding temperature of 80 to 180 ° C., and a molding time of about 10 minutes.
[0023]
【Example】
The embodiments of the present invention are specifically illustrated by the following examples, but the present invention is not limited thereto. The pressure spreadability and viscosity were measured by the following methods.
[0024]
(Measurement of pressure spreadability)
3ton of the resin composition was weighed and pressed with a press machine heated to a hot platen temperature of 50 ° C., with a configuration of upper heating plate / 50 μm thick nylon film / resin composition / 50 μm thick nylon film / lower hot platen, 3 ton. The area where the resin composition spreads is measured using an area meter [manufactured by Hayashi Denko Co., Ltd .: automatic area meter AAM-8].
[0025]
(Evaluation of pressure spreadability)
In the above method, immediately after kneading / mixing the resin composition, and in a state where the resin composition is sealed in a nylon film bag having a thickness of 50 μm, it is left to stand at room temperature for about one day (pressure spreading property) ) Was measured, and it was evaluated whether the obtained resin composition had a viscosity change due to standing at room temperature for 1 day (when no change was observed, it was evaluated that no aging was necessary). In addition, the film-like resin composition stretched between nylon films was visually observed to check for the presence of undissolved polymer.
[0026]
(Measurement of viscosity of slurry resin composition)
It measured by BL viscometer (Tokyo Keiki Co., Ltd. product).
(Evaluation of viscosity of slurry-like resin composition)
By the above method, immediately after kneading of the resin composition, and after placing the resin composition in a polyethylene container, and measuring the viscosity after standing at room temperature for about 1 day with a nylon film having a thickness of 50 μm sealed, it was obtained. It was evaluated whether the resin composition had a viscosity change due to standing at room temperature for 1 day (when no change was observed, it was evaluated that no aging was necessary).
[0027]
(Colorimetry)
It was measured by the method of JIS K 7105 using an SM-2 type colorimeter manufactured by Suga Test Instruments Co., Ltd.
[0028]
Example 1
1.425 kg of methyl methacrylate, 1.075 kg of neopentyl glycol dimethacrylate, 6.85 kg of silane-treated aluminum hydroxide having an average particle size of 8 μ and methacrylic resin beads [98% by weight of methyl methacrylate and 2% by weight of methyl acrylate 2.625 kg of the above copolymer, weight average molecular weight 110000, average particle diameter 0.3 mm] is placed in a roll-type pressure kneader [manufactured by Moriyama Seisakusho, D-10-20 type, mixing capacity 10 liters]. The mixture was dispersed at 30 ° C. for 30 minutes and allowed to stand for 30 minutes to obtain a slurry mixture. Next, the jacket temperature of the kneader was heated to 80 ° C. and kneaded for 7 minutes to obtain a clay-like kneaded material having a temperature of 83 ° C. After cooling to 50 ° C., 50 g of 1,1-di-t-butylperoxy-3,3,5-trimethylcyclohexane was added and mixed for 3 minutes in a pressure kneader. The resulting resin composition had a pressure spreadability of 302 cm ² and was unchanged even after 24 hours.
860 g of the obtained resin composition was put into a 250 mm × 200 mm flat plate mold and subjected to pressure molding under molding conditions of a molding temperature of 130 ° C., a pressurized resin pressure of 100 kgf / cm ² , and a pressing time of 12 minutes, An acrylic artificial marble flat plate of 250 mm × 200 mm × 10 mm was obtained. The obtained molded article had no molding defects such as cracks, no discoloration (colorimetric value: b value 0.31), and was a molded article having a very beautiful surface.
[0029]
Comparative Example 1
Roll-type pressurization of 1.425 kg of methyl methacrylate, 1.075 kg of neopentyl glycol dimethacrylate, 6.85 kg of silane-treated aluminum hydroxide having an average particle size of 8 μm and 2.625 kg of methacrylic resin beads similar to Example 1 The mixture was placed in a kneader (manufactured by Moriyama Seisakusho Co., Ltd., D-10-20 type, mixed volume 10 liters) and kneaded at 60 ° C. for 60 minutes. Next, the kneaded product was cooled to 50 ° C., and then 50 g of 1,1-di-t-butylperoxy-3,3,5-trimethylcyclohexane was added thereto and mixed for 3 minutes.
860 g of the obtained resin composition was put into a 250 mm × 200 mm flat plate mold and subjected to pressure molding under molding conditions of a molding temperature of 130 ° C., a pressurized resin pressure of 100 kgf / cm ² , and a pressing time of 12 minutes, An acrylic artificial marble flat plate of 250 mm × 200 mm × 10 mm was obtained. The obtained molded product was slightly discolored to yellow, and when measured, the b value was as large as 1.34, and the appearance was poor.
[0030]
Example 2
Roll-shaped pressurization of 3.53 kg of methyl methacrylate, 0.67 kg of neopentyl glycol dimethacrylate, 9.75 kg of silane-treated aluminum hydroxide having an average particle size of 8 μm and 1.05 kg of methacrylic resin beads similar to Example 1 The mixture was placed in a kneader (manufactured by Moriyama Seisakusho Co., Ltd., D-10-20 type, mixing volume 10 liters), dispersed at 60 ° C. for 2 minutes, and allowed to stand for 30 minutes to obtain a slurry mixture. Undissolved resin beads were visually observed in the slurry mixture. Next, the jacket temperature of the kneader was heated to 80 ° C. and kneaded for 15 minutes to obtain a slurry-like kneaded product having a temperature of 81 ° C. After cooling this to 50 ° C., 4 g of azoisobutyronitrile was added and stirred and mixed for 10 minutes. The obtained resin composition was in the form of slurry and had a viscosity of 140 poise at 25 ° C., no change in viscosity even after 24 hours, and no undissolved resin beads were observed.
Next, 270 g of the obtained resin composition was poured into a mold having a size of 250 mm × 200 mm × 3 mm, heated at 60 ° C. for 2 hours, and further heated at 120 ° C. for 1 hour to obtain a 250 mm × 200 mm × 3 mm flat plate-shaped acrylic. Obtained artificial marble. The obtained molded article had no molding defects such as cracks or discoloration (colorimetric value: b value 0.29), and had a very beautiful surface.
[0031]
【The invention's effect】
As described above, the present invention can obtain a slurry-like molding material suitable for a casting molding method or a clay-like molding material suitable for a press molding method, and can easily and easily form a molding material for artificial marble. It is suitable as a method for manufacturing at low cost.

Claims (1)

(A) First, a monomer mainly composed of a methacrylic ester, a methacrylic ester polymer and an inorganic filler are mixed, and the methacrylic ester polymer absorbs a monomer mainly composed of a methacrylic ester. A step, (B) a second step of kneading the mixture obtained in the first step at 65 to 120 ° C., and (C) a curing agent after cooling to the slurry-like or clay-like kneaded product obtained in the second step The manufacturing method of the resin composition characterized by comprising from the 3rd process of mixing.