JPH10273573A - Resin composition and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a composition being desirable for use in hot press molding and giving an artificial marble having good falling ball impact strength, no tendency toward discoloration and good beautifulness, heat resistance, chemical resistance, weather resistance, etc., by kneading an unsaturated monomer based on a (meth)acrylic ester, a methyl methacrylate polymer and an inorganic filler in a specified ratio under heating. SOLUTION: 100 pt.wt. unsaturated monomer based on a (meth)acrylic ester, 50-400 pts.wt. particulate methyl methacrylic polymer having a number-average molecular weight of 50,000-600,000 and a particle diameter of 50-1,000 μm and 50-500 pts.wt. inorganic filler having a particle diameter of 0.1-100 μm are kneaded at 65-120 deg.C to obtain a clayish resin composition having a press spreadability of 150-450 cm<2> and a rubber hardness retention of 10-70% after 80 sec in relation to the rubber hardness at the start of measurement. If necessary, the composition may further contain 5-200 pts.wt. reinforcing monofilaments and/or 0-300 pts.wt. partially gel-like methacrylic polymer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[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, countertops, vanities, shower trays, flooring materials, wall materials, partitions, taking advantage of beautiful appearance and excellent characteristics. Widely used for boards. As a method for producing this acrylic artificial marble, a casting method in which an unsaturated monomer mainly composed of (meth) acrylic acid ester or a slurry in which an inorganic filler is dispersed and contained in a syrup is polymerized and cured along a mold. Is generally adopted. However, this casting method has a problem that a long curing time is required and productivity is low.
On the other hand, a method of heating under pressure (hot press molding method) has been proposed as a method of shortening the curing time. In the hot press molding method, it is important that the raw material composition has 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- 1248)
No. 44) or a fine powder of a crosslinked polymer (Japanese Patent Laid-Open No.
There is known a method of adding a thickening agent such as JP-A No. 313019) to impart shape stability to the composition. However, in this method, it takes a long time to thicken, a leaving time called aging time is required, and the addition of the thickener adds aesthetics, heat resistance, and chemical resistance to the acrylic artificial marble. In addition, there is a problem that characteristics such as weather resistance tend to decrease.

Also, 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 that it does not use a thickener which degrades the characteristics of acrylic artificial marble, and can eliminate the production and handling of high-concentration syrup. However, this method also requires an aging step, and has a problem that the composition becomes colored when kneading is continued to shorten the aging time, and that the molded article has a low falling ball impact strength.

[0004]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide good fall impact strength, no discoloration, beautiful appearance,
Heat resistance, chemical resistance, weather resistance, etc. can produce good acrylic artificial marble, to provide a resin composition suitable for hot press molding method, the other object is to economical production method of the resin composition. To provide.

[0005]

According to the present invention, there are provided, according to the present invention, 100 parts by weight of an unsaturated monomer mainly composed of (meth) acrylate, 50 to 400 parts by weight of a methyl methacrylate-based polymer, Mainly composed of 50 to 500 parts by weight of an inorganic filler, and has a spreadability of 150 to 450 cm.
² and 180 with respect to the rubber hardness at the start of the measurement.
A resin composition having a rubber hardness retention after 10 seconds of 10 to 70%, 100 parts by weight of an unsaturated monomer mainly composed of (meth) acrylate, 50 to 400 parts by weight of a methyl methacrylate-based polymer, and inorganic A filler of 50 to 500 parts by weight is kneaded at a temperature of 65 to 120 ° C., the pressure spreadability is in the range of 150 to 450 cm ² , and the rubber hardness retention after 180 seconds with respect to the rubber hardness at the start of the measurement is 10 ~ 70
% Can be achieved by a method for producing a resin composition which obtains a clay-like material having a% content.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The unsaturated monomer mainly composed of (meth) acrylate (meaning acrylate or methacrylate, hereinafter the same) used in the present invention is defined as (meth) acrylate It includes a single compound or a mixture of a (meth) acrylate and another polymerizable monomer. As the ratio of the (meth) acrylate,
In consideration of weather resistance, beauty, chemical resistance, and the like of molded articles such as artificial marble, the content is usually 30% by weight or more, preferably 50% by weight or more, more preferably 70% by weight 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 Esters of acrylic acid with 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.

When the (meth) acrylic acid ester is methyl methacrylate, a molded article having a good balance of beauty, heat resistance, chemical resistance, weather resistance, strength and the like can be obtained, which is particularly preferable. Esters of polyhydric alcohols with methacrylic acid or acrylic acid are preferably used in applications requiring stain resistance and heat resistance.

Examples of other polymerizable monomers used as a mixture with (meth) acrylic acid ester include acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, styrene, α-methylstyrene, vinyl acetate and the like. But not limited thereto.

As the methyl methacrylate-based polymer,
30% by weight of methyl methacrylate units in terms of weather resistance, beauty, chemical resistance, etc. of molded articles such as artificial marble
The above materials are usually used, preferably at least 50% by weight, more preferably at least 70% by weight. 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 number average molecular weight of the methyl methacrylate-based polymer is usually preferably about 50,000 to 600,000, and particularly preferably 70,000 to 200,000. In the resin composition of the present invention, the methyl methacrylate-based polymer needs to be substantially dissolved in an unsaturated monomer mainly composed of (meth) acrylate as described later, and the undissolved polymer If remains,
The ductility under pressure changes with time, and the falling ball strength of the molded article tends to decrease.

The shape of the methyl methacrylate-based polymer is not particularly limited as long as it can be used for kneading with other components, but the handling is easy, the kneading time is short, and the particle size is 50%. It is preferably a granular material of about 1000 μm, and a suspension polymer is particularly preferably used. In addition, methyl methacrylate polymer (meth)
It is also possible to use one containing a part of unsaturated monomer mainly composed of acrylic acid ester in advance.

The content of the methyl methacrylate polymer should be 50 to 400 parts by weight, preferably 80 to 100 parts by weight, based on 100 parts by weight of the unsaturated monomer mainly composed of (meth) acrylate. ３００300 parts by weight. Content of methyl methacrylate polymer is (meth)
If the amount is less than 50 parts by weight with respect to 100 parts by weight of the unsaturated monomer mainly composed of an acrylate ester, the shape stability of the resin composition will be inferior, while if it exceeds 400 parts by weight, the fluidity of the resin composition will be poor. This is inferior and is not preferred.

As the inorganic filler used in the present invention, for example, 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. But not limited to these. Among these, aluminum hydroxide, magnesium hydroxide, silica, and glass are preferred, and aluminum hydroxide is more preferably used, from the viewpoint of exhibiting high-grade appearance, stain resistance, and processing performance in products such as acrylic artificial marble. The inorganic filler generally has a particle diameter of 0.1 to 100 μm, preferably 1 to 30 μm. As the inorganic filler, those subjected to a surface treatment such as a silane treatment are preferably used.

The amount of the inorganic filler to be used must be 50 to 500 parts by weight, preferably 100 to 100 parts by weight, based on 100 parts by weight of the unsaturated monomer mainly composed of (meth) acrylate. 400 parts by weight. If the amount of the inorganic filler used is less than 50 parts by weight with respect to 100 parts by weight of the unsaturated monomer mainly composed of (meth) acrylic acid ester, the hardness and heat resistance of the molded article decrease, and exceed 500 parts by weight. In such a case, the fluidity of the resin composition decreases, which is not preferable.

In the method of the present invention, the purpose of the present invention is to improve the toughness and strength of the molded product obtained in the present invention or to exhibit a reinforcing effect such as suppression of the generation and progress of cracks, as long as the characteristics of the present invention are not impaired. The reinforcing single fiber can be added at the time of kneading or mixing. 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 a convergent type chopped strand of vinylon fiber is used, the fiber shape is 5 to 300 μm in fiber diameter and 3 to 50 m in fiber length.
m, and the amount of addition is preferably
The amount is preferably in the range of 5 to 200 parts by weight with respect to 100 parts by weight of the monomer mainly composed of methacrylate used in the present invention. If the addition amount is less than 5 parts by weight, it is difficult to exert the reinforcing effect, and if the addition amount exceeds 200 parts by weight, kneading with a usual apparatus becomes extremely difficult.

In the present invention, a methacrylic partially crosslinked gel polymer can be added for the purpose of further improving the low shrinkage, the processing characteristics, and imparting the design. A methacrylic partially crosslinked gel polymer which can be preferably used for this purpose is described, for example, in JP-A-60-20212.
No. 8, JP-A-62-1705, etc., (a) Alkyl methacrylate alone, α, β-ethylenically unsaturated monomer containing alkyl methacrylate as a main component. A resin material selected from the group consisting of a monomer mixture with a monomer and a syrup containing these polymers, and (b) a mixture comprising 2 to 250 parts by weight of a crosslinking agent per 100 parts by weight of the resin material. A partially crosslinked gel-like weight in which the content of the polymer is increased by 4 to 75% by weight from the total polymer content in the mixture within a range where the total polymer content does not exceed 90% by weight by partially polymerizing the polymer. It is united. The alkyl methacrylate is not particularly limited and can be appropriately selected from those mentioned above as the methacrylic acid ester. The α, β-ethylenically unsaturated monomer and the crosslinking agent are not particularly limited. However, it can be appropriately selected from those listed as other unsaturated monomers copolymerizable with the methacrylic acid ester.

The methacrylic partially crosslinked gel-like polymer is preferably used after being crushed, and usually has an average particle diameter of 5 mm or less, preferably about 0.1 to 3 mm. The mixing ratio of the methacrylic partially crosslinked gel polymer is usually 0 to 300 parts by weight, preferably 10 to 100 parts by weight, based on 100 parts by weight of a monomer mainly composed of methacrylic acid ester.
The content is preferably from 200 to 200 parts by weight, more preferably from 15 to 150 parts by weight.

In the method of the present invention, various resins containing a coloring agent, an inorganic filler and the like are crushed at the time of kneading or mixing, if necessary, as long as the object of the present invention is not hindered. The resulting pattern material, coloring agent, coupling agent,
Additives such as light stabilizers, antioxidants, mold release agents, polymerization regulators, and defoamers can also be used in combination. The (meth) acrylic used in the present invention for the purpose of improving the rate of thickening in the mixing and kneading steps in the present invention and improving the transferability to a mold when a molded article is manufactured from the resin composition. A resin composition which is insoluble in an unsaturated monomer mainly composed of an acid ester and has a degree of swelling can also be added.

The resin composition of the present invention needs to have a pressure spreadability of 150 to 450 cm ² , preferably 200 to 400 cm ² . The pressure spreadability as referred to herein is one index indicating the fluidity of the resin composition,
Specifically, it refers to a physical value measured by the following operation.
That is, first, 30.0 g of the resin composition was weighed, and the press machine heated to a hot platen temperature of 50 ° C. was used to construct a hot platen / 50 μm thick nylon film / resin composition / 50 μm thick nylon film / lower platen. Is a measured value of the spread area of the resin composition when a load of 3 tons is applied for 60 seconds. When this pressure spreadability is lower than 150 cm ² ,
Although shape retention is good, in hot press molding, fluidity is insufficient and molding defects such as defective filling are likely to occur. On the other hand, when it exceeds 450 cm ² , shape retention is poor,
This is not preferable because the workability is poor and the productivity is reduced, and burrs are easily generated in hot press molding.

The resin composition of the present invention is characterized in that an excellent resin composition having substantially no change over time in pressure spreadability can be obtained. Substantially no change with time means that there is almost no change in the rate of change in pressurization spreadability within 5% immediately after kneading and after 48 hours. If there is a change over time,
There is a tendency that the falling ball impact strength of the molded article tends to decrease, and the fluidity varies, so that the quality of the molded article is not constant and appearance defects such as color unevenness occur. Causes of the change with time are that unmelted resin remains, kneading is insufficient and the composition is not uniform, or a stable kneading state is not reached. Such a change with time is observed in a resin composition produced by kneading with a curing agent at a low temperature employed in the conventional method.

The resin composition of the present invention further has a rubber hardness retention of 180 seconds after the start of measurement with respect to the rubber hardness value.
It needs to be 0-70%. The rubber hardness retention is a physical quantity strongly related to the viscoelastic properties of the resin composition, particularly the creep properties. Here, the rubber hardness refers to a hardness at 25 ° C. measured with an Asker rubber hardness meter F (manufactured by Kobunshi Keiki Co., Ltd.). 10% rubber hardness retention
When a lower value is exhibited, the value indicates that a sufficient amount of a polymer having a high-molecular-weight linear portion or a cross-linked polymer substance is not present in the resin composition, and the result is as follows. As a result, only a resin composition molded article having a low falling ball impact strength can be obtained. If the rubber hardness retention exceeds 70%, it becomes very difficult to shape and mold the resin composition. The novel resin composition having a rubber hardness retention in the range of 10 to 70% is obtained by using the constituent materials of the resin composition of the present invention in an amount of usually 65 to 12%.
It can be manufactured by kneading at 0 ° C.

A curing agent is usually added to the resin composition of the present invention for thermosetting. As the curing agent, an azobis compound or an organic peroxide that is a radical polymerization initiator,
For example, azobisisobutyronitrile, benzoyl peroxide, t-butyl peroxide, cumene hydroxy peroxide, t-butyl hydroperoxide,
One or more of dicumyl peroxide and 1,1-di-t-butylperoxy-3,3,5-trimethylcyclohexane can be used. The curing agent is used in an amount 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. The curing agent is usually uniformly mixed with the resin composition obtained as a clay-like material after or during the cooling process.

The method for producing the resin composition of the present invention can be obtained by kneading the above-mentioned raw materials excluding the curing agent at a high temperature of 65 to 120 ° C. For example, as can be seen in the method of Japanese Patent Publication No. Hei 5-13899, it is common knowledge of engineers in this field that the kneading of the polymerizable substance is performed at a low temperature.
Even after kneading for 0 minutes, some resin remained without being dissolved, and if the resin was to be completely dissolved, the kneaded material was colored and the molded product was also colored, and a favorable result was not obtained. The present inventors have studied diligently the solution of the above problem, surprisingly from the general tendency of increasing the temperature to color easily, without coloring by kneading at a high temperature,
It has been found that a clay-like material having no residual resin is obtained, and that a molded product using this composition has excellent physical properties which cannot be realized by a conventional method, and has led to the present invention. Further, according to the production method of the present invention, the composition can be produced in a short time and the aging time is not required as compared with the conventional method.

The kneading temperature for producing the resin composition of the present invention must be in the range of 65 to 120 ° C.
Preferably it is 70-100 degreeC. If the kneading temperature is less than 65 ° C., the resin remains without dissolving, and the product such as artificial marble obtained by coloring and molding is inferior in beauty and inferior in physical properties such as falling ball impact strength. Becomes
On the other hand, if the kneading temperature is higher than 120 ° C., the polymerization of the monomer and the decomposition of the resin composition are apt to occur, which is not preferable.

The method for kneading the above raw materials is not particularly limited, but includes a sigma type blade kneader, a Z type blade kneader, a spiral type blade kneader, a blade type continuous kneader, a paddle mixer, a continuous paddle mixer, a ribbon mixer, a co-kneader, and a roll type. It is preferable to use a pressure kneader, a roll-type internal mixer, a continuous kneader, a single-screw extruder, a twin-screw extruder, or the like, and a twin-screw extruder is particularly preferably used in terms of kneading time. The kneading time varies depending on the type of kneader, the number of rotations and the kneading temperature, but generally about 2 to 10 minutes is employed. The resin composition of the present invention is suitably used for hot press molding, but is not limited thereto, and can be used for molding methods such as injection molding and transfer molding. Further, the use of the molded article is not limited to artificial marble.

[0026]

The present invention will now 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, rubber hardness retention, falling ball impact strength, and colorimetry were measured and evaluated by the following methods.

(Measurement of Extensibility under Pressure) First, 3 parts of the resin composition
Weigh 0.0 g and shape into a sphere. At this time, the shape of the resin composition does not need to be a strict sphere, but an extreme rod-like or disk-like form may affect the measured value, so that it is avoided. After shaping, the resin composition was heated on a hot platen at a temperature of 50 ° C. using a hot platen / 50 μm
Thickness nylon film / resin composition / 50 μm thickness nylon film / lower heating plate
The pressure is applied for 2 seconds, and the spread area of the resin composition is measured using an area meter (manufactured by Hayashi Denko KK: automatic area meter AAM-8).

(Measurement of Rubber Hardness Retention Rate) Using an Asker Rubber Hardness Tester Model F (manufactured by Kobunshi Keiki Co., Ltd.) under the condition of 25 ° C. and a load of 500 g, the rubber was measured at the start of the measurement and 180 seconds after the start of the measurement. The hardness value is read, and the percentage of the rubber hardness value after 180 seconds with respect to the rubber hardness value at the start of the measurement is defined as the retention.

(Measurement of impact strength of falling ball) JIS K72
The 50% breaking energy was determined by the method of No. 11, and this was defined as the falling ball impact strength. Falling ball impact test equipment is JIS K
The steel ball used was JIS ball type 2 (1 ± 0.05 kg, diameter of about 63 mm). The test piece size is a square of 150 ± 1 mm on one side.

(Colorimetric method) The colorimetric measurement was carried out according to the method of JIS K 7105 using an SM-2 type colorimeter (manufactured by Suga Test Instruments Co., Ltd.).

Example 1 60 parts by weight of methyl methacrylate, 30 parts by weight of neopentyl glycol dimethacrylate and 0.2% of 2,2'-azobis (4-methoxy-2,4-divaleronitrile).
003 parts by weight was mixed and dissolved, and the mixture was poured into a cell assembled with two glass plates and a gasket at 10 mm intervals, and polymerized at 60 ° C. for 2 hours to obtain a polymer content of 3
8% by weight of an acrylic partially crosslinked gel polymer was obtained.

Next, 2.5 kg of a mixture of 57 parts by weight of methyl methacrylate and 43 parts by weight of neopentyl glycol dimethacrylate, and 2.35 kg of the above partially crosslinked gel polymer were subjected to a pressure kneader [Moriyama Seisakusho Co., Ltd .: D-10-20 type pressure kneader, mixing volume 10 liter, blade rotation speed 45 rpm, power 15 kW], and further 280 parts by weight of aluminum hydroxide, methacrylic resin beads (98% by weight of methyl methacrylate and 2% by weight of methyl acrylate) Copolymer, weight average molecular weight 110,000, average particle diameter 0.3 mm) 50 parts by weight,
A mixture of 48 parts by weight of a stone-like pattern material and 32 parts by weight of vinylon fiber [RF-S602 manufactured by Kuraray Co., Ltd.] 15.10 k
g. These raw materials were kneaded for 20 minutes while being heated at a heating medium temperature of 90 ° C. using a jacket attached to a pressure kneader, and then cooled to 50 ° C., followed by 1,1-di-t-butylperoxy-3. 87 g of 3,3,5-trimethylcyclohexane was supplied and mixed for 5 minutes to obtain a resin composition.

The resulting resin composition has a pressure spreadability of 280.
In cm ² , no residual resin beads were observed. In addition, the pressure spreadability of the resin composition after standing for 48 hours was 280.
No change was observed in cm ² after mixing. The rubber hardness immediately after the start of the measurement was 98, the rubber hardness after 180 seconds was 36.0, and the retention was 36.7%. next,
240 g of the obtained resin composition is 250 mm × 200 mm
Into a flat plate mold having a size of 130 mm, a molding temperature of 130 ° C., a resin pressure of 100 kgf / cm ² , and a pressure molding time of 6 minutes.
A 3 mm plate-shaped artificial marble was obtained. Defects such as cracks and sink marks were not observed on the surface of the obtained molded product, and it was very beautiful.

Example 2 In the pressure kneader used in 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 diameter of 8 μm, 2.625 kg of methacrylic resin beads as in Example 1 and 1.175 kg of a stone-like pattern material having an average particle size of 0.3 mm produced by pulverizing a cross-linked acrylic resin were charged, and the jacket temperature of the pressure kneader was decreased. The mixture was heated to 80 ° C and kneaded for 10 minutes to obtain a clay-like resin composition having a temperature of 87 ° 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. Pressure spreadability is 299cm ²
And the spreadability under pressure after 48 hours was also 299 cm ² . The rubber hardness immediately after the start of the measurement was 96 and 180.
The rubber hardness after 1 second was 14.5, and the retention was 15.1%.

10 kg of the obtained resin composition is placed on the top plate 60
It is poured into a vanity mold having a height of 0 mm × 1000 mm and a height of 50 mm and a back guard, and is subjected to a molding temperature of 130 ° C., a resin pressure of 100 kgf / cm ² , and a pressing time of 12 minutes. Press forming, 60
A vanity table of acrylic artificial marble measuring 0 mm × 1000 mm × 10 mm was obtained. The obtained molded article had no molding defects such as cracks and had an extremely beautiful surface. A 150 mm × 150 mm square sample was cut out from the vanity stand, and the falling ball impact strength was measured. As a result, the molded product had a high falling ball impact strength of 3.3 J and was highly practical.

Example 3 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 liquid obtained by mixing 57 parts by weight of methyl methacrylate and 43 parts by weight of neopentyl glycol dimethacrylate in a liquid mixing tank was supplied from the liquid mixing tank at a feed rate of 10 kg / hour by a metering pump. 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 42.6 kg / hour using a powder quantitative feeder. Supplied with The jacket of the kneader was heated through a heating medium at 90 ° C. 8
A clay-like resin composition at a temperature of 0 ° C. was obtained. 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 mixed with the pressure kneader used in Example 1 for 3 minutes. did. The spreadability under pressure was 295 cm ² ,
After 8 hours, the spreadability under pressure was 294 cm ² , which was almost the same. The rubber hardness immediately after the start of the measurement was 94, the rubber hardness after 180 seconds was 12.2, and the retention was 13.0%.

860 g of the obtained resin composition was weighed at 250 mm
× 200 mm into a flat mold, molding temperature 130
C., pressurized resin pressure 100 kgf / cm ² , pressurized time 12 min.
A flat plate of acrylic artificial marble of 0 mm × 10 mm was obtained.
The resulting molded article had no molding defects such as cracks, no discoloration (b value was 0.61 as measured by colorimetry), and had a very beautiful surface. When a 150 mm x 150 mm square sample was cut out and the falling ball impact strength was measured,
It had a high falling ball impact strength of 3.6 J and was a highly practical molded product.

Comparative Example 1 1.425 kg of methyl methacrylate, 1.075 kg of neopentyl glycol dimethacrylate and 1,1-
50 g of di-tert-butylperoxy-3,3,5-trimethylcyclohexane and 6.85 kg of silane-treated aluminum hydroxide having an average particle size of 8 μm are dispersed in the pressure kneader used in Example 1, and then dispersed. 2.625 kg of the same methacrylic resin beads as in Example 1 were kneaded at room temperature for 10 minutes to obtain a slurry-like resin composition having the same raw material composition as in Example 2. This was aged at room temperature for 2 days in a sealed state to obtain a solid resin composition. Its press spreadability is 344cm
It was ² , but 322 cm ² after 48 hours.
The rubber hardness immediately after the start of the measurement was 92, and the rubber hardness after 180 seconds was 6.2 and the retention was 6.7%. 860 g of the obtained resin composition was put into a 250 mm × 200 mm flat plate mold, and a molding temperature of 130 ° C. and a pressure resin pressure of 100
Pressure molding was performed under the molding conditions of kgf / cm ² and a pressure time of 12 minutes to obtain a 250 mm × 200 mm × 10 mm acrylic artificial marble plate. No discoloration was observed in the obtained molded product (b value of the colorimetry was 0.55), but 150
A sample having a size of 150 mm × 150 mm was cut out, and the falling ball impact strength was measured.

Comparative Example 2 1.425 kg of methyl methacrylate, 1.075 kg of neopentyl glycol dimethacrylate and 1,1-
50 g of di-tert-butylperoxy-3,3,5-trimethylcyclohexane and 6.85 kg of silane-treated aluminum hydroxide having an average particle size of 8 μm are dispersed in the pressure kneader used in Example 1, and then dispersed. 2.625 kg of the same methacrylic resin beads as in Example 1 were kneaded at 60 ° C. for 60 minutes to obtain a clay-like resin composition having the same raw material composition as in Example 2. Its pressure spreadability was 299 cm ² , but it was 283 cm ² after 48 hours. The rubber hardness immediately after the start of the measurement was 90, and the rubber hardness after 180 seconds was 8.5 and the retention was 9.4%. 860 g of the obtained resin composition was put into a 250 mm × 200 mm flat plate mold, and a molding temperature of 130 ° C. and a pressure resin pressure of 100 kgf /
Pressure molding was performed under the molding conditions of 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 turned yellow and was measured for color. The b value was as large as 1.24, and the appearance was poor. When a 150 mm × 150 mm square sample was cut out and the falling ball impact strength was measured, it was as weak as 2.5 J.

Comparative Example 3 2.625 kg of the same methacrylic resin beads as in Example 1
Was dissolved in 1.425 kg of methyl methacrylate and 1.075 kg of neopentyl glycol dimethacrylate, and 1,1-di-t-butylperoxy-3,
50 g of 3,5-trimethylcyclohexane and 6.8 of silane-treated aluminum hydroxide having an average particle size of 8 μm.
5 kg was kneaded with the pressure kneader used in Example 1 at room temperature for 30 minutes to obtain a clay-like resin composition having the same raw material composition as in Example 2. This pressure spreadability is 292 cm ² ,
Even after the elapse of 48 hours, there was no change of 292 cm ² , but the rubber hardness immediately after the start of the measurement was 86, the rubber hardness after 180 seconds was 7.8, and the retention was 9.0%. 860 g of the obtained resin composition was put into a flat plate mold of 250 mm × 200 mm, and the molding temperature was 130 ° C. and the pressure resin pressure was 100 k.
Pressure molding was performed under molding conditions of gf / 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 turned yellow and was measured for color. The b value was as large as 1.49, and the appearance was poor. When a 150 mm × 150 mm square sample was cut out and the falling ball impact strength was measured, it was 2.4.
It was J and weak.

Comparative Example 4 In a pressure kneader used in Example 1, 1.995 kg of methyl methacrylate, 1.505 kg of neopentyl glycol dimethacrylate, 6.85 kg of silane-treated aluminum hydroxide having an average particle diameter of 8 μm were prepared. 1.625 kg of the same methacrylic resin beads as in Example 1 were added, the jacket temperature of the kneader was raised to 80 ° C, and the mixture was kneaded for 10 minutes to obtain a soft clay-like resin composition having a temperature of 82 ° C.
After cooling this resin composition to 50 ° C, 1,1-di-
50 g of t-butylperoxy-3,3,5-trimethylcyclohexane was added and mixed for 3 minutes. The pressure spreadability was 472 cm ² , and the pressure spreadability after 48 hours was 47
It was 0 cm ² . The obtained product was too soft and the shape changed during handling, making it difficult to handle. It was placed in the mold of Example 1 and molding was attempted. Heat and pressure molding was carried out in the same manner as in Example 1, but burrs were severe and no molded product could be obtained.

From the above Examples and Comparative Examples, when the resin composition obtained by the conventional method was used, the falling ball impact strength of the molded product was lower than that using the resin composition of the present invention. It is clear that the molded product may be colored.

[0043]

According to the resin composition of the present invention, it is possible to produce a beautiful molded article such as an acrylic technical marble having a good falling ball impact strength, no discoloration, and a resin composition capable of producing such a molded article. A simple and economical method for producing a product can be provided.

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

Claims (5)

[Claims] 1. 100 parts by weight of an unsaturated monomer mainly composed of (meth) acrylate, 50 to 400 parts by weight of a methyl methacrylate-based polymer, and 50 to 50 parts of an inorganic filler.
Mainly from 0 parts by weight, and the pressure spreadability is 150 to 45.
A 0 cm ^2, and a resin composition, wherein the rubber hardness retention of 180 seconds after the rubber hardness at the start of measurement is 10 to 70%. 2. 100 parts by weight of an unsaturated monomer mainly composed of (meth) acrylic acid ester, 5 to 200 parts by weight of a reinforcing single fiber and / or 0 to 300 parts by weight of a methacrylic partially crosslinked gel polymer The resin composition according to claim 1, wherein parts are added and mixed. 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. The resin composition according to claim 1, wherein: 4. 100 parts by weight of an unsaturated monomer mainly composed of (meth) acrylate, 50 to 400 parts by weight of a methyl methacrylate-based polymer, and 50 to 50 parts of an inorganic filler.
0 parts by weight are kneaded at a temperature of 65 to 120 ° C., the pressure spreadability is in the range of 150 to 450 cm ² , and the rubber hardness retention after 180 seconds with respect to the rubber hardness at the start of the measurement is 10%.
A method for producing a resin composition, comprising obtaining the above clay-like material. 5. 5 to 200 parts by weight of a reinforcing single fiber and / or 0 to 300 parts by weight of a methacrylic partially crosslinked gel polymer per 100 parts by weight of an unsaturated monomer mainly composed of a (meth) acrylic ester. The method for producing a resin composition according to claim 4, wherein parts are mixed.