JP3370549B2 - Acrylic resin composition, acrylic premix, method for producing acrylic artificial marble, and thickener - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an acrylic resin composition having stable quality, high productivity, useful as a raw material of an acrylic premix excellent in handleability and moldability, and having high productivity. The present invention relates to a method for producing an acrylic artificial marble having a good appearance and a thickener.

[0002]

2. Description of the Related Art Acrylic artificial marble in which an acrylic resin is mixed with an inorganic filler such as aluminum hydroxide has various excellent functional characteristics such as excellent appearance, soft hand and weather resistance. Widely used for counters such as kitchen counters, vanities, waterproof pans, and other construction applications. These are generally manufactured by a method in which a so-called slurry in which an inorganic filler is dispersed in an acrylic syrup is filled in a molding die and is cured and polymerized at a relatively low temperature. However, since this acrylic syrup has a low boiling point, it is unavoidable to lower the curing temperature, which requires a long molding time, resulting in low productivity. In addition, the shape of the molded product is limited due to the problem of filling the slurry into the mold.

In order to improve these drawbacks, studies have been conventionally made to produce an acrylic artificial marble by heat-pressing a premix obtained by thickening a resin syrup with a thickener.

[0004] For example, in Japanese Patent Laid-Open No. 32720/1993, acrylic resin for artificial marble, which has good handleability and moldability, is obtained by blending an acrylic syrup with a crosslinked resin powder having a specific degree of swelling obtained by suspension polymerization. A system premix is disclosed. Further, JP-A-6-298883 discloses an acrylic premix for artificial marble, which contains a thermoplastic acrylic resin powder that is hardly soluble in acrylic syrup and is excellent in low shrinkage during heat curing. ing. Further, in JP-A-6-313019, a resin powder obtained by spray-drying a cross-linked polymer obtained by emulsion polymerization is blended with an acrylic syrup to prevent cracking during molding and to improve the appearance of a molded product. Also disclosed is an acrylic premix for artificial marble, which is characterized by improving the stability of thickening.

[0005]

However, Japanese Unexamined Patent Publication No. 5-3.
In order to thicken the acrylic syrup with the resin powder as disclosed in Japanese Patent No. 2720 and Japanese Patent Application Laid-Open No. 6-298883, a large amount of resin powder is required, resulting in high manufacturing cost. Further, there is a problem that productivity is reduced because thickening requires a long time.

Further, even when the resin powder as disclosed in Japanese Patent Laid-Open No. 6-313019 is used for thickening, it takes a long time to thicken it to a level at which heat and pressure molding is possible. It has a problem that the premix (about 24 hours) needs to be matured.

An object of the present invention is to increase the viscosity of an acrylic resin composition in a short time, an acrylic premix which has high productivity and is suitable for high-temperature molding and has excellent moldability and processability.
A method for producing an acrylic artificial marble having a good appearance, and
It is to provide a thickener suitable for these applications.

[0008]

Means for Solving the Problems As a result of studying the above-mentioned problems, the present inventors have made an acrylic resin that thickens in a short time by incorporating a specific polymer powder into an acrylic syrup as a thickener. The present invention has been completed by finding a method for producing a composition, an acrylic premix suitable for high-temperature molding and excellent in moldability, and an acrylic artificial marble having high productivity and good surface appearance.

That is, the present invention is a secondary agglomerate in which primary particles agglomerate with each other and has a specific surface area of 1 to 100 m ² / g.
Acrylic thickener for syrup consisting of non-crosslinked polymer powder, and methyl methacrylate or (meth)
The present invention relates to an acrylic resin composition comprising an acrylic monomer mixture (a) and an acrylic syrup composed of polymethylmethacrylate or an acrylic copolymer (b). The present invention relates to an acrylic premix characterized by containing an acrylic resin composition and an inorganic filler, and relates to a method for producing an acrylic artificial marble characterized by heating and pressurizing the acrylic premix. And is a secondary aggregate in which primary particles are aggregated, and has a specific surface area of 1 to 10
The present invention relates to a thickener for acrylic syrup, which is characterized by comprising a polymer powder having a range of 0 m ² / g.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The polymer powder used in the acrylic resin composition of the present invention is used as a thickener for an acrylic syrup, and is a secondary aggregate in which primary particles are aggregated. It is necessary to use a non-crosslinked polymer having a specific surface area of 1 to 100 m ² / g.

This is because when the polymer powder has the shape of a secondary agglomerate, the absorption speed of the acrylic syrup component is high and the viscosity increase tends to be extremely good.

The average particle size of the primary particles of the polymer powder is 0.
The average particle size of the secondary agglomerates is preferably in the range of 1 to 250 μm. The average particle size of the primary particles is 0.03 μm.
By the above, the yield at the time of producing the polymer powder which is a secondary aggregate tends to be good, and when it is 1 μm or less, a sufficient thickening effect can be obtained by using a small amount of the polymer powder. , Because thickening is possible in a short time,
When the acrylic resin composition containing the polymer powder is used for the production of granite-like artificial marble, the productivity is improved, and the sharpness of the stone pattern is improved, and the unevenness of the stone pattern is eliminated. This is because there is a tendency. More preferably,
It is in the range of 0.07 to 0.7 μm.

When the average particle size of the secondary agglomerates is 1 μm or more, the powder dusting tends to be reduced and the handling property of the polymer powder tends to be good. The appearance of the molding material obtained,
This is because the gloss and the surface smoothness tend to be particularly good. The range is more preferably 5 to 150 μm, further preferably 10 to 70 μm.

This also gives the polymer powder a specific surface area of 1
When the content is m ² / g or more, a sufficient thickening effect can be obtained by using a small amount of the polymer powder, and the thickening can be performed in a short time, so that the productivity is improved, and further, this polymer is used. when using an acrylic resin composition comprising a powder in the manufacture of granite finished artificial marble, the better the sharpness of pebbled pattern, tend to pattern non-uniformity of the pebble is lost, also, 100 m ²
/ G or less, the dispersibility of the polymer powder in the acrylic syrup becomes good, and therefore the handleability at the time of thickening becomes good, and the acrylic resin composition containing the polymer powder and the acrylic syrup This is because the kneadability at the time of producing the acrylic premix tends to be good. The range is more preferably 3 to 100 m ² / g, and further preferably 5 to 100 m ² / g.

The degree of swelling of the polymer powder with respect to methyl methacrylate is not particularly limited, but is preferably 16 times or more. This is because when the degree of swelling is 16 times or more, the effect of thickening the acrylic syrup becomes sufficient. More preferably 2
It is 0 times or more.

The polymer constituting the polymer powder is composed of a non-crosslinked polymer. This is because the polymer powder is a non-crosslinked polymer powder, so that a sufficient thickening effect can be obtained in a short time, and an acrylic resin composition containing this polymer powder is used for producing a granite-like artificial marble. This is because the sharpness of the stone pattern tends to improve and the unevenness of the stone pattern tends to disappear. In this case, when the balance between the thickening effect and the thickening time is taken into consideration, the weight average molecular weight of the polymer powder of the non-crosslinked polymer is preferably 100,000 or more.
The range is more preferably 100,000 to 3,500,000, further preferably 300,000 to 3,000,000, and particularly preferably 500 to 2,000,000.

As the polymer constituting the polymer powder, various polymers can be appropriately selected and used according to need, and are not particularly limited, but the appearance of the obtained acrylic artificial marble is pointed out. Taking this into consideration, an acrylic polymer is preferable.

The constituents of the polymer powder include, for example,
Alkyl (meth) having an alkyl group having 1 to 20 carbon atoms
Acrylate, cyclohexyl (meth) acrylate,
Glycidyl (meth) acrylate, hydroxyalkyl (meth) acrylate, (meth) acrylic acid, (meth)
Acrylic acid metal salts, fumaric acid, fumaric acid ester, maleic acid, maleic acid ester, aromatic vinyl, vinyl acetate, (meth) acrylic acid amide, (meth) acrylonitrile, vinyl chloride, maleic anhydride and the like can be mentioned. These may be polymerized alone, or may be copolymerized by using two or more kinds in combination, if necessary, in consideration of the affinity with the monomer component constituting the acrylic syrup. (Meth) acrylic monomers are preferred.

When the polymer powder is crosslinked,
Ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, 1,3-butylene glycol di (meth) acrylate, 1,4-butylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) Acrylate, dimethylolethanedi (meth) acrylate, 1,1-dimethylolpropane di (meth) acrylate, 2,2-dimethylolpropane di (meth) acrylate, trimethylolethanetri (meth) acrylate, trimethylolpropane tri (Meth) acrylate, tetramethylolmethane tri (meth) acrylate, tetramethylolmethane di (meth) acrylate, neopentyl glycol di (meth)
Acrylate and polyfunctional ester of (meth) acrylic acid with polyhydric alcohol such as polyethylene glycol, polypropylene glycol, pentaerythritol, dipentaerythritol, etc., polyfunctional monomer such as divinylbenzene, triaryl isocyanurate, aryl methacrylate, etc. The body can be used as a constituent component, and these can be used alone or in combination of two or more kinds.

Further, the polymer powder used in the present invention is
A polymer powder having a so-called core / shell structure composed of a core phase and a shell phase having different chemical compositions, structures, molecular weights and the like of the polymers forming them may be used. In this case, the core phase may be a non-crosslinked polymer or a crosslinkable polymer, but the shell phase is a non-crosslinked polymer.

As the constituent components of the core phase and shell phase of the polymer powder, for example, one or more selected from the components listed above as the constituent components of the polymer powder may be appropriately used. You can

Further, the polymer powder of the present invention may contain an inorganic filler, but it is preferable not to contain the inorganic filler in order to enhance the thickening effect.

The method for producing the polymer powder is not particularly limited, and examples thereof include bulk polymerization, solution polymerization, suspension polymerization,
It can be obtained by a known method such as emulsion polymerization or dispersion polymerization. Among them, a method of obtaining a polymer powder by subjecting an emulsion obtained by emulsion polymerization to treatments such as spray drying, freeze drying, and salt / acid precipitation is preferable because of good production efficiency.

The acrylic syrup used in the acrylic resin composition of the present invention includes methyl methacrylate or a (meth) acrylic monomer mixture (a), and polymethylmethacrylate or an acrylic copolymer ( b).

The methyl methacrylate constituting the acrylic syrup or the (meth) acrylic monomer mixture (a) preferably contains 50 to 50 parts of methyl methacrylate.
It is an unsaturated monomer or unsaturated monomer mixture containing 100% by weight. The content of the component (a) in the acrylic syrup is not particularly limited, but workability when the acrylic resin composition of the present invention is used as an acrylic premix, and the acrylic premix Considering physical properties such as mechanical strength when using as a raw material of acrylic artificial marble,
A range of 30 to 90% by weight is preferable. This is because by setting the content of the component (a) to 30% by weight or more, the viscosity of the syrup becomes low and the handleability thereof becomes good, and the content of the component (a) is set to 90% by weight or less. This is because the shrinkage ratio during curing tends to be low. The range is more preferably 40 to 85% by weight, and further preferably 50 to 80% by weight.

Examples of the monomer other than methyl methacrylate used as the component (a) include (meth) acrylic acid ester having an alkyl group having 1 to 20 carbon atoms, cyclohexyl (meth) acrylate, glycidyl (meth).
Acrylate, hydroxyalkyl (meth) acrylate, (meth) acrylic acid, (meth) acrylic acid metal salt,
Fumaric acid, fumaric acid ester, maleic acid, maleic acid ester, aromatic vinyl, vinyl acetate, (meth) acrylic acid amide, (meth) acrylonitrile, vinyl chloride,
Monofunctional monomers such as maleic anhydride, and ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, 1,3-butylene glycol di (meth) acrylate, 1,4-butylene glycol di ( (Meth) acrylate, 1,6-hexanediol di (meth) acrylate, dimethylolethanedi (meth) acrylate, 1,1-dimethylolpropane di (meth) acrylate, 2,2-dimethylolpropane di (meth) acrylate , Trimethylolethane tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, tetramethylolmethane tri (meth) acrylate, tetramethylolmethane di (meth) acrylate, neopentyl glycol di (meth)
Acrylate and polyfunctional ester of (meth) acrylic acid with polyhydric alcohol such as polyethylene glycol, polypropylene glycol, pentaerythritol, dipentaerythritol, etc., polyfunctional monomer such as divinylbenzene, triaryl isocyanurate, aryl methacrylate, etc. The body. These may be used alone or in combination of two or more as required.

In order to impart strength, solvent resistance, heat resistance, dimensional stability and the like to a molded article obtained by using the acrylic resin composition of the present invention, a polyfunctional monofunctional compound is added to the component (a). It is preferable to include a monomer. In this case, the amount of the polyfunctional monomer used is not particularly limited, but in order to effectively obtain the above effects, it is preferably used in the range of 3 to 50% by weight in the component (a).

Further, it is particularly preferable to use neopentyl glycol dimethacrylate as the monomer used in the component (a) since a molded product having extremely excellent surface gloss can be obtained. In this case, neopentyl glycol dimethacrylate and another polyfunctional monomer may be used in combination. The blending amount of neopentyl glycol dimethacrylate is not limited, but is preferably 50% by weight or more in the monomer other than methyl methacrylate in the component (a).

The polymethylmethacrylate or acrylic copolymer (b) constituting the acrylic syrup used in the acrylic resin composition of the present invention preferably has a repeating unit of methylmethacrylate structure of 50 to 100.
It is an acrylic polymer in the range of mol%.

The content of the component (b) in the acrylic syrup is not particularly limited, but the workability when the acrylic resin composition of the present invention is used as an acrylic premix, and this acrylic 10-70% by weight considering physical properties such as mechanical strength when acrylic premix is used as raw material for acrylic artificial marble
Is preferred. More preferably 15 to 60% by weight,
More preferably, it is in the range of 20 to 50% by weight.

The component (b) may be a cross-linked polymer or a non-cross-linked polymer and can be appropriately selected as needed, but in consideration of the fluidity of the resin composition obtained and the mechanical strength of the molding material. When added, its weight average molecular weight is 15,0.
It is preferably in the range of 00 to 300,000. More preferably, it is in the range of 25,000 to 250,000.

As the constituent component other than methyl methacrylate used in the component (b), for example, the monomer used in the component (a) can be applied as it is. As the component (b), two or more kinds can be used in combination, and the above polyfunctional monomer can be copolymerized as necessary. The component (b) can be produced by a known polymerization method such as a solution polymerization method, a bulk polymerization method, an emulsion polymerization method or a suspension polymerization method.

The acrylic syrup used in the acrylic resin composition of the present invention may be one prepared by dissolving the component (b) in the component (a), or by partially polymerizing the component (a) (a). The component (b), which is a polymer thereof, may be produced in the component (b), or the partially polymerized component further added with the component (a), or the partially polymerized component (b) further added. May be added.

The content of the polymer powder and the acrylic syrup in the acrylic resin composition of the present invention is not particularly limited, but 0.1 to 100 parts by weight of the polymer powder is added to 100 parts by weight of the acrylic syrup. It is preferably within the range of parts. This is because when the amount of the polymer powder used is 0.1 parts by weight or more, a high thickening effect tends to be exhibited, and when the amount is 100 parts by weight or less,
This is because the dispersibility of the polymer powder tends to be good and the cost tends to be advantageous. The more preferable amount of the polymer powder used is in the range of 1 to 80 parts by weight.

The acrylic resin composition of the present invention can be made into an acrylic premix which is particularly useful as a raw material for an acrylic artificial marble by adding an inorganic filler and other additives as required. The acrylic premix of the present invention has the characteristics that it is not sticky, has good handleability, and can be easily weighed.

In the acrylic premix of the present invention, the inorganic filler is preferably used in the range of 50 to 400 parts by weight with respect to 100 parts by weight of the acrylic resin composition. This is because when the amount of the inorganic filler used is 50 parts by weight or more, the obtained molded product has good texture and heat resistance, and when it is 400 parts by weight or less, a molded product having high strength can be obtained. This is because it tends to be possible to obtain.

As the inorganic filler, aluminum hydroxide, silica, fused silica, calcium carbonate, barium sulfate, titanium oxide, calcium phosphate, talc, clay,
Inorganic fillers such as glass powder can be appropriately used if necessary. In particular, when using the acrylic premix of the present invention as a molding material for artificial marble,
As the inorganic filler, aluminum hydroxide, silica, fused silica and glass powder are preferable.

In the acrylic premix of the present invention, if necessary, benzoyl peroxide, lauroyl peroxide, t-butyl hydroperoxide, cyclohexanone peroxide, methyl ethyl peroxide, t-butyl peroxide octoate, t-butyl peroxybenzoate, dicumyl peroxide,
Organic peroxides such as 1,1-bis (t-butylperoxy) 3,3,5-trimethylcyclohexane and azobisisobutyronitrile, curing agents such as azo compounds, and reinforcing materials such as glass fibers and carbon fibers. , Various additives such as colorants and low-shrinking agents can be added. In addition, in particular, the addition of zinc stearate makes it possible to obtain a molded product having even more excellent gloss. The compounding amount of zinc stearate is not particularly limited, but acrylic premix 10
The range of 0.05 to 4.0 parts by weight is preferable with respect to 0 parts by weight. More preferably, it is in the range of 0.1 to 2.0 parts by weight.

Further, by blending the acrylic premix of the present invention with inorganic filler-containing resin particles and molding, a granite-like artificial marble having a clear stone pattern and excellent design can be obtained. it can. This is because the acrylic premix of the present invention does not require an aging period and thickens in a short time after the completion of kneading, so that the swelling of the inorganic filler-containing resin particles causes the blurring of the interface of the stone part. It is thought to be suppressed.

The compounding amount of the resin particles containing an inorganic filler is not particularly limited, but it is preferably in the range of 1 to 200 parts by weight with respect to 100 parts by weight of the acrylic premix.
This is because by setting the amount of the inorganic filler-containing resin particles to be 1 part by weight or more, a stone pattern with good design tends to be obtained, and by setting it to 200 parts by weight or less,
This is because the kneadability during the production of the acrylic premix tends to be good. More preferably 10 to 1
It is in the range of 00 parts by weight.

The resin forming the inorganic filler-containing resin particles may be any resin that does not dissolve in methyl methacrylate, and examples thereof include crosslinked acrylic resin, crosslinked polyester resin and crosslinked styrene resin. A crosslinked acrylic resin is preferable because it has a high affinity with the resin composition and a molded product having a beautiful appearance can be obtained. The crosslinked acrylic resin may contain polymethylmethacrylate or a non-crosslinked acrylic polymer containing methylmethacrylate as a main component.

The inorganic filler constituting the inorganic filler-containing resin particles is preferably used in the range of 50 to 400 parts by weight with respect to 100 parts by weight of the resin. This is because when the amount of the inorganic filler used is 50 parts by weight or more, the texture and heat resistance of the obtained molded product are good, and the amount of the inorganic filler used is 400 parts by weight or less. ,
This is because it tends to be possible to obtain a molded product having high strength.

As the inorganic filler, aluminum hydroxide, silica, fused silica, calcium carbonate, barium sulfate, titanium oxide, calcium phosphate, talc, clay,
Inorganic fillers such as glass powder can be appropriately used if necessary. In particular, when producing a granite-like artificial marble, the inorganic filler is preferably aluminum hydroxide, silica, fused silica, or glass powder.

The method for producing the resin particles containing an inorganic filler is not particularly limited. For example, a resin molded product containing an inorganic filler obtained by polymerization and curing by a hot pressing method, a casting method or the like is crushed and classified by a sieve. There is a method of doing. For example, a method of pulverizing and classifying the acrylic artificial marble molded as described above is preferable.

In the present invention, one kind or two or more kinds of inorganic filler-containing resin particles having different colors and particle sizes can be used. The particle size of the inorganic filler-containing resin particles is not particularly limited as long as it is not more than the wall thickness of the molded product.

The method of mixing the constituents for obtaining the acrylic resin composition of the present invention and the acrylic premix using the same is not particularly limited as long as it is a method capable of efficiently mixing a highly viscous substance. For example, a kneader, mixer, roll, extruder or the like can be used.

The acrylic artificial marble of the present invention can be obtained by filling the acrylic premix of the present invention in a molding die and heating and pressurizing it. Specific examples of the heating and pressurizing method include a compression molding method, an injection molding method, and an extrusion molding method, but are not particularly limited.

[0048]

EXAMPLES The present invention will be specifically described below with reference to examples. All parts and percentages in the examples are by weight.

Physical properties of polymer powder: Measured by nitrogen adsorption method using a surface area meter SA-6201 (manufactured by Horiba Ltd.).

Average particle size: Measured using a laser diffraction / scattering type particle size distribution measuring device (LA-910, manufactured by Horiba Ltd.).

Weight average molecular weight: measured value by GPC method (in terms of polystyrene) Swelling degree: Polymer powder was put into a graduated cylinder of 100 ml, tapped several times to fill 5 ml, and then cooled to 10 ° C. or lower methyl methacrylate. Is added so that the total amount becomes 100 ml, and rapidly stirred so that the whole is uniform. Then, the graduated cylinder was kept in a constant temperature bath at 25 ° C. for 1 hour, and the volume of the polymer powder layer after swelling was determined and shown by the ratio to the volume before swelling (5 ml).

Physical properties of acrylic syrup: Weight average molecular weight: measured value by GPC method (1) Production example of polymer powder (P-1 to P-3) Cooling pipe, thermometer, stirrer, dropping device, nitrogen introduction A reactor equipped with a tube was charged with 925 parts of pure water, 5 parts of sodium alkyldiphenyl ether disulphonate (manufactured by Kao Corporation, trade name Perex SS-H), and 1 part of potassium persulfate, and stirred under a nitrogen atmosphere. While heating to 70 ° C. To this, a mixture of 500 parts of methyl methacrylate and 5 parts of sodium dialkylsulfosuccinate (Kao Corporation, trade name Perex OT-P) was added dropwise over 3 hours, and then the mixture was kept for 1 hour and then heated to 80 ° C. The emulsion was polymerized by heating and holding for 1 hour, and the polymer had a primary particle size of 0.
An 08 μm emulsion was obtained.

The emulsion thus obtained was spray-dried at inlet temperature / outlet temperature = 150 ° C./90° C. using a Parbis GB-22 type spray dryer manufactured by Yamato Scientific Co., Ltd. 8 μm non-crosslinked polymer powder (P-
1) was obtained.

The emulsion thus obtained was spray-dried using an L-8 type spray dryer manufactured by Okawara Kakoki Co., Ltd.,
Non-crosslinked polymer powder (P-2) having an average particle diameter of the secondary aggregate particles of 30 μm was obtained.

The emulsion obtained in the same manner was used as No. Spray-drying treatment was carried out using a 62TF type spray dryer to obtain a non-crosslinked polymer powder (P-3) having secondary aggregate particles having an average particle diameter of 100 μm.

The resulting non-crosslinked polymer powder (P-1 to P-
3) was completely dissolved in methyl methacrylate and had a swelling degree of 20 or more. Other physical property values are shown in Table 1.

(2) Production Example of Polymer Powder (P-4) A reactor equipped with a cooling pipe, a thermometer, a stirrer, a dropping device, and a nitrogen introducing pipe was charged with 625 parts of pure water and sodium alkyldiphenyl ether disulphonate. (Kao Corporation, trade name Perex SS-H) 3 parts and potassium persulfate 0.5 part were charged and heated to 70 ° C. with stirring under a nitrogen atmosphere. To this, a mixture of 500 parts of methyl methacrylate and 5 parts of sodium dialkylsulfosuccinate (Kao Corporation, trade name Perex OT-P) was added dropwise over 3 hours, and then the mixture was kept for 1 hour and then heated to 80 ° C. Warm 1
The emulsion polymerization was terminated by holding for a period of time to obtain an emulsion having a polymer primary particle diameter of 0.11 μm.

The emulsion thus obtained was subjected to an inlet temperature / outlet temperature = 1 using an L-8 type spray dryer manufactured by Okawara Kakoki Co., Ltd.
Spray-drying treatment was carried out at 50 ° C / 90 ° C to obtain a non-crosslinked polymer powder (P-4) having secondary aggregate particles having an average particle diameter of 40 µm.

The obtained (P-4) was completely dissolved in methyl methacrylate, and the degree of swelling was 20 times or more. Other physical property values are shown in Table 1.

(3) Production Example of Polymer Powder (P-5) A reactor equipped with a cooling pipe, a thermometer, a stirrer, a dropping device, and a nitrogen introducing pipe was charged with 925 parts of pure water and sodium alkyldiphenyl ether disulphonate. (Kao Corporation, trade name Perex SS-H) 2 parts and potassium persulfate 0.5 part were charged and heated to 70 ° C. with stirring under a nitrogen atmosphere. To this, a mixture of 480 parts of methyl methacrylate, 20 parts of ethyl acrylate and 5 parts of sodium dialkylsulfosuccinate (Kao Corporation, trade name Perex OT-P) was added dropwise over 3 hours and then held for 1 hour, The temperature was further raised to 80 ° C. and maintained for 1 hour to complete the emulsion polymerization, and an emulsion having a polymer primary particle diameter of 0.2 μm was obtained.

The obtained emulsion was used as an inlet temperature / outlet temperature = 1 using an L-8 type spray dryer manufactured by Okawara Kakoki Co., Ltd.
Spray-drying treatment was carried out at 20 ° C./60° C. to obtain a non-crosslinked polymer powder (P-5) having secondary aggregate particles having an average particle diameter of 30 μm. The obtained (P-5) was completely dissolved in methyl methacrylate, and the degree of swelling was 20 or more. Other physical property values are shown in Table 1.

(4) Production Example of Polymer Powder (P-6) A reactor equipped with a cooling pipe, a thermometer, a stirrer, a dropping device and a nitrogen introducing pipe was charged with 925 parts of pure water and sodium polycarboxylate (Kao). 5 parts of Poise 530, trade name, manufactured by K.K., and 2 parts of potassium persulfate were charged, and the mixture was stirred under a nitrogen atmosphere while stirring 7
Heated to 0 ° C. To this, methyl methacrylate 500
Part, sodium dialkyl sulfosuccinate (Kao Corporation)
Made, trade name Perex OT-P) 3 parts of the mixture was added dropwise over 3 hours, then held for 1 hour, and then at 80 ° C.
The temperature was raised to and held for 1 hour to complete the emulsion polymerization, and an emulsion having a polymer primary particle diameter of 0.6 μm was obtained.

The obtained emulsion was subjected to an inlet temperature / outlet temperature = 1 using an L-8 type spray dryer manufactured by Okawara Kakoki Co., Ltd.
Spray-drying treatment was carried out at 50 ° C./90° C. to obtain a non-crosslinked polymer powder (P-6) having secondary aggregate particles having an average particle diameter of 45 μm. The obtained (P-6) was completely dissolved in methyl methacrylate and had a swelling degree of 20 or more. Other physical property values are shown in Table 1.

(5) Production Example of Polymer Powder (P-7) A reactor equipped with a cooling pipe, a thermometer, a stirrer, a dropping device, and a nitrogen introducing pipe was charged with 925 parts of pure water and sodium alkyldiphenyl ether disulphonate. (Kao Corporation, trade name Perex SS-H) (5 parts) and potassium persulfate (0.25 part) were charged, and the mixture was heated to 70 ° C. with stirring under a nitrogen atmosphere. To this, 149.85 parts of methyl methacrylate,
1,3-butylene glycol dimethacrylate 0.15
Part, sodium dialkyl sulfosuccinate (Kao Corporation)
Made by trade name Perex OT-P) 5 parts of the mixture was added dropwise over 1.5 hours and then held for 1 hour, then 350 parts of methyl methacrylate was added dropwise over 3.5 hours and then maintained for 1 hour. Then, the temperature was further raised to 80 ° C. and the temperature was maintained for 1 hour to complete the emulsion polymerization.
A 1 μm emulsion was obtained.

The obtained emulsion was subjected to an inlet temperature / outlet temperature = 1 using an L-8 type spray dryer manufactured by Okawara Kakoki Co., Ltd.
A spray drying treatment was carried out at 50 ° C./90° C. to obtain a polymer powder (P-7) having a core / shell structure in which the average particle size of the secondary aggregate particles was 30 μm. The degree of swelling of the obtained polymer powder having a core / shell structure was 20 or more. Other physical property values are shown in Table 1.

(6) Production Example of Polymer Powder (P-8) The monomer to be dripped was 497.5 parts of methyl methacrylate,
2.5 parts of 1,3-butylene glycol dimethacrylate and sodium dialkylsulfosuccinate (Kao Corporation)
Manufactured by the trade name Perex OT-P) except that it is a mixture consisting of 5 parts, to obtain an emulsion having a polymer primary particle diameter of 0.18 μm in the same manner as in the production example of the polymer powder (P-5). Spray drying was carried out to obtain a crosslinked polymer powder (P-8) having an average particle diameter of the secondary aggregate particles of 30 μm. The physical property values are shown in Table 1.

(7) Production Example of Polymer Powder (P-9) A reactor equipped with a cooling pipe, a thermometer, a stirrer, a dropping device, and a nitrogen introducing pipe was charged with 925 parts of pure water and sodium alkyldiphenyl ether disulphonate. (Kao Corporation, trade name Perex SS-H) 5 parts and potassium persulfate 1 part were charged and heated to 70 ° C. with stirring under a nitrogen atmosphere. To this, a mixture of 350 parts of methyl methacrylate, 150 parts of n-butyl acrylate and 5 parts of sodium dialkylsulfosuccinate (Kao Corporation, trade name Perex OT-P) was added dropwise over 3 hours and then held for 1 hour. Then, the temperature was further raised to 80 ° C. and maintained for 1 hour to complete the emulsion polymerization, and an emulsion having a polymer primary particle diameter of 0.15 μm was obtained.

The obtained emulsion was subjected to an inlet temperature / outlet temperature = 1 using an L-8 type spray dryer manufactured by Okawara Kakoki Co., Ltd.
A spray drying treatment was carried out at 20 ° C / 50 ° C to obtain a non-crosslinked polymer powder (P-9) having secondary aggregate particles having an average particle diameter of 30 µm. The degree of swelling of the obtained (P-9) was 1.2. Other physical property values are shown in Table 1.

(8) Production Example of Polymer Powder (P-10) A reactor equipped with a cooling tube, a thermometer, a stirrer, and a nitrogen introducing tube was charged with 800 parts of pure water and polyvinyl alcohol (saponification degree: 8).
8%, degree of polymerization 1000) 1 part was dissolved, and then a monomer solution in which 400 parts of methyl methacrylate and 0.5 part of azobisisobutyronitrile were dissolved was added and stirred at 400 rpm under a nitrogen atmosphere. While heating to 80 ° C. in 1 hour, the mixture was heated as it was for 2 hours. Then, the temperature was raised to 90 ° C. and the mixture was heated for 2 hours, and further heated to 120 ° C. to distill away the residual monomer together with water to obtain a slurry, and the suspension polymerization was completed. The obtained slurry was filtered, washed, and then dried with a hot air dryer at 50 ° C. to obtain a non-crosslinked polymer powder (P-10) having an average particle diameter of 88 μm. The degree of swelling of the obtained (P-10) was 1.2. Other physical property values are shown in Table 1.

(9) Production Example of Polymethyl Methacrylate (B-1) in Acrylic Syrup A reactor equipped with a cooling tube, a thermometer, a stirrer, and a nitrogen introducing tube was charged with 800 parts of pure water and polyvinyl alcohol (saponification). Degree 8
8%, polymerization degree 1000) 1 part was dissolved, and then a monomer solution in which 400 parts of methyl methacrylate, 2 parts of normaldodecyl mercaptan, and 2 parts of azobisisobutyronitrile were dissolved was added, and under a nitrogen atmosphere, While stirring at 400 rpm, the temperature was raised to 80 ° C. in 1 hour, and heating was continued for 2 hours. After that, the temperature is raised to 90 ° C. and heated for 2 hours, then 1
The residual monomer was distilled off together with water by heating to 20 ° C. to obtain a slurry, and the suspension polymerization was completed. The obtained slurry is filtered and washed, and then dried with a hot air dryer at 50 ° C. to obtain polymethylmethacrylate (B-1) having an average particle size of 93 μm.
Got The weight average molecular weight of the obtained (B-1) was 40,000.

(10) Production Example of Polymer (B-2) Mainly Containing Methyl Methacrylate in Acrylic Syrup The monomer solution to be charged is methyl methacrylate 376.
Part, methyl acrylate 24 parts, normal dodecyl mercaptan 1.2 parts and azobisisobutyronitrile 2 parts, except that the stirring speed is 300 rpm, except that the stirring speed is 300 rpm. By the method, a polymer (B-2) containing methyl methacrylate as a main component was obtained. The obtained (B-2) had an average particle diameter of 350 μm and a weight average molecular weight of 120,000.

(11) Production Example of Polymer (B-3) Mainly Containing Methyl Methacrylate in Acrylic Syrup The monomer solution to be added is methyl methacrylate 368.
Part, n-butyl acrylate 32 parts, normal dodecyl mercaptan 1.6 parts and azobisisobutyronitrile 2 parts, and a stirring speed of 300 rpm.
A polymer (B-3) containing methyl methacrylate as a main component was obtained in the same manner as in Production Example (9) except that. The average particle size of the obtained (B-3) was 350 μm,
The weight average molecular weight was 70,000.

(12) Production Example of Resin Particles (C) Containing Inorganic Filler From 69% methyl methacrylate, 2% ethylene glycol dimethacrylate, and 29% polymethyl methacrylate (B-1) obtained in the above Production Example (9). To 100 parts of acrylic syrup, t-butyl peroxybenzoate (manufactured by NOF CORPORATION, trade name Perbutyl Z) as a curing agent 2.0 parts Zinc stearate as an internal release agent 0.5
Part, 0.25 part of white inorganic pigment or black inorganic pigment, 200 parts of aluminum hydroxide (manufactured by Showa Denko KK, trade name Heidilite H-310) is added as an inorganic filler, and the above production is further performed. 30 parts of the polymer powder (P-2) obtained in Example (1) was added and kneaded with a kneader for 10 minutes to obtain an acrylic premix. Next, the acrylic premix was filled in a 200 mm square flat mold and the mold temperature was set to 130 ° C. and the pressure was set to 100 kg / cm ² for 10 minutes.
It was heated and pressed and cured for a minute to obtain an acrylic artificial marble having a thickness of 10 mm. The obtained acrylic artificial marble was crushed with a crusher to obtain white or black inorganic filler-containing resin particles (C) having an average particle diameter of 350 μm. The powder characteristics are shown in Table 3.

[0074]

[Table 1]

[0075]

[Table 2]

[0076]

[Table 3]

[Example 1] Methyl methacrylate 35
%, Neopentyl glycol dimethacrylate 30%,
Polymethylmethacrylate (B obtained in the above Production Example (9)
-1) 100 parts of acrylic syrup consisting of 35%,
Dicumyl peroxide as a curing agent (NOF CORPORATION)
1.5 parts by trade name, Park Mill D), and 0.5 parts by weight of zinc stearate as an internal mold release agent, and then aluminum hydroxide as an inorganic filler (manufactured by Showa Denko KK, trade name Hydilite H-). 310) 200 parts, and further 25 parts of the polymer powder (P-1) obtained in the above Production Example (1) were added and kneaded with a kneader for 10 minutes to obtain an acrylic premix. The obtained acrylic premix had no stickiness immediately after kneading and was easy to handle. Table 4 shows the results of the thickening evaluation.

Next, the obtained acrylic premix was filled in a 200 mm square flat molding die, and was heated and pressurized and cured for 10 minutes under the conditions of a die temperature of 140 ° C. and a pressure of 100 kg / cm ² . An acrylic artificial marble having a thickness of 10 mm was obtained. The surface of the obtained artificial marble was in a mirror-like state with no defects and had a good appearance.

[Example 2] Methyl methacrylate 48
%, Neopentyl glycol dimethacrylate 27%,
Polymethylmethacrylate (B obtained in the above Production Example (9)
-1) To 100 parts of acrylic syrup consisting of 25%,
After adding t-butyl peroxybenzoate (manufactured by NOF CORPORATION, trade name Perbutyl Z) 1.5 parts as a curing agent and 0.5 parts zinc stearate as an internal release agent,
Aluminum hydroxide as an inorganic filler (Showa Denko KK)
Manufactured by Hijilite H-310 (trade name) was added, and the polymer powder (P-
2) 30 parts was added and kneaded with a kneader for 10 minutes to obtain an acrylic premix. The obtained acrylic premix had no stickiness immediately after kneading and was easy to handle. Table 4 shows the results of the thickening evaluation.

Next, the obtained acrylic premix was filled in a 200 mm square flat mold and was heated and pressurized and cured for 10 minutes under the conditions of a mold temperature of 130 ° C. and a pressure of 100 kg / cm ² . An acrylic artificial marble having a thickness of 10 mm was obtained. The surface of the obtained artificial marble was in a mirror-like state with no defects and had a good appearance.

Example 3 Methyl Methacrylate 65
%, 1,3-butylene glycol dimethacrylate 15
%, 100 parts of an acrylic syrup consisting of 20% of the polymer (B-2) containing methyl methacrylate obtained in the above Production Example (10) as a main component, and 1,1-bis (t
-Butylperoxy) 3,3,5-trimethylcyclohexane (Nippon Yushi Co., Ltd., trade name Perhexa 3M)
After adding 1.5 parts and 0.5 part of zinc stearate as an internal mold release agent, aluminum hydroxide (manufactured by Showa Denko KK, trade name Heidilite H-310) as an inorganic filler
190 parts was added, and further 40 parts of the polymer powder (P-3) obtained in the above Production Example (1) was added and kneaded with a kneader for 10 minutes to obtain an acrylic premix. The obtained acrylic premix had no stickiness immediately after kneading and was easy to handle. Table 4 shows the results of the thickening evaluation.

Then, the obtained acrylic premix was filled in a 200 mm square flat mold, and heated and pressurized for 10 minutes under the conditions of a mold temperature of 120 ° C. and a pressure of 100 kg / cm ² , An acrylic artificial marble having a thickness of 10 mm was obtained. The surface of the obtained artificial marble was in a mirror-like state with no defects and had a good appearance.

[Example 4] Methyl methacrylate 65
%, Ethylene glycol dimethacrylate 3%, and 32% of the polymer (B-3) containing methyl methacrylate obtained in the above Production Example (11) as a main component in 100 parts of acrylic syrup, and azobisisobutyrate as a curing agent. 1.3 parts of ronitrile (manufactured by Wako Pure Chemical Industries, Ltd., trade name V-60),
After adding 1 part of zinc stearate as an internal mold release agent, 210 parts of aluminum hydroxide (manufactured by Showa Denko KK, trade name Heidilite H-310) was added as an inorganic filler, and the above Production Example (2) was added. ) Polymer powder (P
-4) 25 parts was added and kneaded with a kneader for 10 minutes to obtain an acrylic premix. The obtained acrylic premix had no stickiness immediately after kneading and was easy to handle. Table 4 shows the results of the thickening evaluation.

Next, the obtained acrylic premix was filled in a 200 mm square flat mold, and heated and pressurized for 10 minutes under the conditions of a mold temperature of 110 ° C. and a pressure of 100 kg / cm ² , An acrylic artificial marble having a thickness of 10 mm was obtained. The surface of the obtained artificial marble was in a mirror-like state with no defects and had a good appearance.

[Example 5] Methyl methacrylate 58
%, Trimethylolpropane trimethacrylate 7%,
Polymethylmethacrylate (B obtained in the above Production Example (9)
-1) 100 parts of acrylic syrup consisting of 35%,
After adding 1.3 parts of azobisisobutyronitrile (manufactured by Wako Pure Chemical Industries, Ltd., trade name V-60) as a curing agent and 1 part of zinc stearate as an internal release agent, water as an inorganic filler. 250 parts of aluminum oxide (manufactured by Showa Denko KK, trade name Hydilite H-310) was added, and further 20 parts of the polymer powder (P-5) obtained in the above Production Example (3) was added and kneadered. The mixture was kneaded for 10 minutes to obtain an acrylic premix. The obtained acrylic premix had no stickiness immediately after kneading and was easy to handle. Table 4 shows the results of the thickening evaluation.

Next, the obtained acrylic premix was filled in a 200 mm square flat mold and was heated and pressurized and cured for 10 minutes at a mold temperature of 100 ° C. and a pressure of 100 kg / cm ² . An acrylic artificial marble having a thickness of 10 mm was obtained. The surface of the obtained artificial marble was in a mirror-like state with no defects and had a good appearance.

Example 6 Methyl Methacrylate 58
%, Trimethylolpropane trimethacrylate 7%,
Polymethylmethacrylate (B obtained in the above Production Example (9)
-1) 100 parts of acrylic syrup consisting of 35%,
After adding 1.3 parts of t-butylperoxy octate (Nippon Oil & Fats Co., Ltd., trade name Perbutyl O) as a curing agent and 1 part of zinc stearate as an internal release agent, aluminum hydroxide as an inorganic filler. (Showa Light Metal Co., Ltd.
250 parts of Hydilite H-310 (trade name) was added, and the polymer powder (P-6) 20 obtained in the above Production Example (4) was further added.
Parts were added and kneaded with a kneader for 10 minutes to obtain an acrylic premix. The obtained acrylic premix had no stickiness immediately after kneading and was easy to handle. Table 4 shows the results of the thickening evaluation.

Next, the obtained acrylic premix was filled in a 200 mm square flat mold, and heated and pressurized for 10 minutes under the conditions of a mold temperature of 95 ° C. and a pressure of 50 kg / cm ² , An acrylic artificial marble having a thickness of 10 mm was obtained. The surface of the obtained artificial marble was in a mirror-like state with no defects and had a good appearance.

Example 7 Methyl methacrylate 58
%, Trimethylolpropane trimethacrylate 7%,
Polymethylmethacrylate (B obtained in the above Production Example (9)
-1) 100 parts of acrylic syrup consisting of 35%,
After adding 1.3 parts of t-butylperoxy octate (Nippon Oil & Fats Co., Ltd., trade name Perbutyl O) as a curing agent and 1 part of zinc stearate as an internal release agent, aluminum hydroxide as an inorganic filler. (Showa Light Metal Co., Ltd.
250 parts of Hydilite H-310 (trade name) was added, and the polymer powder (P-7) 20 obtained in the above Production Example (5) was further added.
Parts were added and kneaded with a kneader for 10 minutes to obtain a mixture. This mixture was allowed to stand at room temperature to obtain an acrylic premix with good stickiness and no stickiness. Table 4 shows the results of the thickening evaluation.

Next, the obtained acrylic premix was filled in a 200 mm square flat mold, and heated and pressurized for 10 minutes under the conditions of a mold temperature of 95 ° C. and a pressure of 50 kg / cm ² , An acrylic artificial marble having a thickness of 10 mm was obtained. The surface of the obtained artificial marble was in a mirror-like state with no defects and had a good appearance.

[Reference Example 1] An acrylic premix was obtained in the same manner as in Example 7 except that the polymer powders (P-8) were used. Table 4 shows the results of the thickening evaluation. The resulting acrylic premix had no stickiness and was easy to handle. The acrylic artificial marble obtained by the same method as in Example 7 had a mirror-like state with no defects and had a good appearance.

[Comparative Examples 1 and 2] Example 7 except that polymer powders (P-9) and (P-10) were used, respectively.
An acrylic premix was obtained in the same manner as in. Table 4 shows the results of the thickening evaluation.

It took 16 hours or more for thickening, and the obtained premix was sticky and had poor handleability.

Comparative Example 3 An acrylic premix was obtained in the same manner as in Example 7 except that white inorganic filler-containing resin particles (C) were used as the polymer powder. The acrylic premix was sticky even after 20 hours or more after kneading, and had poor handleability.

The appearance of the acrylic artificial marble obtained by the same method as in Example 7 was poor.

Example 8 100 parts of an acrylic syrup consisting of 48% methyl methacrylate, 27% neopentyl glycol dimethacrylate and 25% polymethyl methacrylate (B-1) obtained in the above Production Example (9) was cured. After adding 1.5 parts of t-butyl peroxybenzoate (manufactured by NOF CORPORATION, trade name Perbutyl Z) as an agent and 0.5 part of zinc stearate as an internal release agent, aluminum hydroxide as an inorganic filler. (Showa Denko KK, trade name Heidilite H-
310) 150 parts and 70 parts of the black and white inorganic filler-containing resin particles (C) obtained in the above Production Example (12) are added,
Further, the polymer powder (P-2) 3 obtained in the above Production Example (1)
0 part was added and the mixture was kneaded with a kneader for 10 minutes. The resulting acrylic premix had no stickiness immediately after kneading and was easy to handle.

Next, the obtained acrylic premix was filled in a 200 mm square flat mold, and heated and pressurized for 10 minutes under the conditions of a mold temperature of 130 ° C. and a pressure of 100 kg / cm ² , A 10 mm thick granite-like acrylic artificial marble was obtained. The surface of the obtained granite-like artificial marble had a mirror surface with no defects and had a clear stone pattern, and the appearance was very good.

Example 9 Acrylic syrup was made of 48% methyl methacrylate,
An acrylic premix obtained in the same manner as in Example 8 except that the acrylic syrup was 14% of neopentyl glycol dimethacrylate, 13% of ethylene glycol dimethacrylate and 25% of polymethylmethacrylate (B-1). The handleability was good with no stickiness immediately after kneading.

Next, the surface of the granite-like artificial marble obtained by heat-pressing the obtained acrylic premix in the same manner as in Example 8 was in a mirror state and had a good appearance. .

Example 10 Acrylic syrup was made of 48% methyl methacrylate,
An acrylic syrup consisting of 27% of ethylene glycol dimethacrylate and 25% of polymethylmethacrylate (B-1), with an initiator of 1,1, -bis (t-butylperoxy) 3,3,5-trimethylcyclohexane (NOF Corporation). The acrylic premix obtained by the same method as in Example 8 except that the trade name was Perhexa 3M manufactured by Co., Ltd. was not sticky immediately after kneading and was easy to handle.

Next, the surface of the granite-like artificial marble obtained by heat-pressing the obtained acrylic premix in the same manner as in Example 8 was in a mirror state and had a good appearance. .

Example 11 An acrylic premix obtained by the same method as in Example 8 except that the internal mold release agent was 5.0 parts of zinc stearate and the initiator was changed to Perhexa 3M was prepared immediately after kneading. However, it was not sticky and was easy to handle.

Next, the surface of the granite-like artificial marble obtained by heating and pressing the obtained acrylic premix in the same manner as in Example 8 was in a mirror state and had a good appearance. .

[Example 12] The same procedure as in Example 8 was carried out except that the internal release agent was 0.5 part of Aerosol OT-100 (manufactured by Mitsui Cyminad Co., Ltd.) and the initiator was Perhexa 3M. The acrylic premix had no stickiness immediately after kneading and was easy to handle.

Next, the surface of the granite-like artificial marble obtained by heating and pressing the obtained acrylic premix in the same manner as in Example 8 was in a mirror state and had a good appearance. .

[Comparative Example 4] Methyl methacrylate 48
%, Neopentyl glycol dimethacrylate 27%,
Polymethylmethacrylate (B obtained in the above Production Example (9)
-1) To 100 parts of acrylic syrup consisting of 25%,
After adding 1.5 parts of t-butyl peroxybenzoate (trade name Perbutyl Z, manufactured by NOF CORPORATION) as a curing agent and 0.5 part of zinc stearate as an internal release agent,
Aluminum hydroxide as an inorganic filler (Showa Denko KK)
200 parts of Hydilite H-310 (trade name), and 100 parts of the black and white inorganic filler-containing resin particles (C) obtained in the above Production Example (12) were added, and the mixture was kneaded for 10 minutes with a kneader. The resulting acrylic premix was sticky even after 20 hours or more after kneading, and had poor handleability.

Next, the obtained acrylic premix was filled in a 200 mm square flat mold, and heated and pressurized for 10 minutes under the conditions of a mold temperature of 130 ° C. and a pressure of 100 kg / cm ² , A 10 mm-thick stone-grained acrylic artificial marble was obtained. The obtained molded product had a poor stone pattern and was inferior in design.

[0108]

[Table 4]

[0109]

[Table 5]

Thickening of premix ⊚: Thickening immediately after kneading gave a premix with good handleability without stickiness.

◯: A premix having good handleability without stickiness was obtained, but it took 16 hours or more for thickening.

Δ: It took 16 hours or more for thickening, the obtained premix was sticky, and the handleability was poor.

X: Sticky even after 20 hours or more, and handling property was extremely poor.

Gloss of molded product A: The gloss is extremely high.

◯ +: The gloss is considerably high.

◯: High gloss

Δ: There is gloss.

X: The gloss is low.

Surface smoothness of molded products ⊚: No pinholes and extremely high surface smoothness.

◯: No pinhole and high surface smoothness.

Δ: There are pinholes and the surface smoothness is low. X: There are many pinholes and the surface smoothness is extremely low.

Sharpness of molded product ⊚: Very clear and very excellent in design.

B: Clear and excellent in design.

Δ: The stones are slightly blurred and the design is poor.

X: Stones are blurred and the design is very poor.

Uneven pattern of stone pattern of molded product A: There is no pattern unevenness and the design is very good.

A: There is no pattern unevenness and the design is excellent.

Δ: There is pattern unevenness and the design is poor.

X: Pattern unevenness is severe and design is very poor.

[0130]

As is clear from the above examples, by using the polymer powder of the present invention, it is possible to obtain an acrylic resin composition having excellent thickening properties, and the acrylic resin composition The resin composition makes it possible to obtain a premix that is suitable for high-temperature molding and has excellent moldability, and the acrylic artificial marble produced using this has an excellent appearance. Above is very useful.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI C04B 24:26) C04B 103: 44 103: 44 111: 54 111: 54 (56) References JP-A-6-313019 (JP, JP, A) JP 7-188505 (JP, A) JP 9-111086 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C08L 33/06-33/12 C04B 26 / 06

Claims (5)

(57) [Claims] 1. A thickener for acrylic syrup, which is a secondary agglomerate in which primary particles are agglomerated and has a specific surface area of 1 to 100 m ² / g, and a methyl methacrylate, Alternatively, an acrylic resin composition comprising a (meth) acrylic monomer mixture (a) and an acrylic syrup made of polymethylmethacrylate or an acrylic copolymer (b). 2. An acrylic premix containing the acrylic resin composition according to claim 1 and an inorganic filler. 3. The acrylic premix according to claim 2, further comprising resin particles containing an inorganic filler. 4. A method for manufacturing an acrylic artificial marble, which comprises heating and curing the acrylic premix according to claim 2. 5. A thickener for an acrylic syrup, which is a secondary agglomerate in which primary particles are agglomerated and has a specific surface area in the range of 1 to 100 m ² / g.