JPH10265639A - Acrylic premix and acrylic artificial marble with marble texture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an acrylic premix which has a short thickening time and excellent handleability and moldability and to provide an acrylic artificial marble with a marble texture having a clear surface appearance. SOLUTION: This premix contains an acrylic syrup (A) consisting of methyl methacrylate alone or a monomer mixture mainly comprising it (a) and polymethyl methacrylate or a polymer formed mainly from methyl methacrylate (b), an inorg. filler (B), resin particles contg. an inorg. filler (C), and a noncross- linked polymer powder (D) having a bulk density of 0.1-0.7 g/ml, a linseed oil absorption of 60-200 ml/100g, and a swellability by methyl methacrylate of 1,600 vol.% or higher. The acrylic artificial marble with a marble texture is produced by thermally curing the premix under presure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acrylic premix and a stone-like acrylic artificial marble. More specifically, the present invention relates to an acrylic premix having excellent productivity, excellent handleability and moldability, and a stone-grained acrylic artificial marble having stable quality and excellent design.

[0002]

2. Description of the Related Art Acrylic artificial marble in which an inorganic filler such as aluminum hydroxide is blended with an acrylic resin has various excellent functional properties such as excellent molded appearance, soft touch and weather resistance. It is widely used for counters such as kitchen counters, vanities, waterproof pans, and other architectural uses. These are generally produced by a method in which a so-called slurry in which an inorganic filler is dispersed in an acrylic syrup is filled in a mold, and this is cured and polymerized at a relatively low temperature. However, since the acrylic syrup has a low boiling point, the curing temperature has to be lowered, and as a result, a long molding time is required, resulting in low productivity.
In addition, because there is a problem with the filling of the slurry into the mold,
It has the disadvantage that the shape of the molded article is limited. Furthermore, when artificial marble having a stone pattern is produced by including resin particles that do not dissolve in the slurry, since the resin particles tend to settle in the slurry during curing polymerization, the resulting artificial marble is obtained. Has the disadvantage that the stone pattern tends to be non-uniform. In order to improve these drawbacks, studies have been made on the production of acrylic artificial marble by heating and press-molding a premix obtained by thickening a resin syrup with a thickener.

For example, Japanese Patent Application Laid-Open No. 5-32720 discloses an acrylic for artificial marble having excellent handleability and moldability in which a crosslinked resin powder having a specific degree of swelling obtained by suspension polymerization is blended into an acrylic syrup. JP-A-6-298883 discloses an acrylic premix in which a thermoplastic acrylic resin powder that is hardly soluble in the acrylic syrup is blended with an acrylic syrup, and has a low shrinkage during heat curing. An acrylic premix for artificial marble having excellent properties is disclosed. In addition, Japanese Unexamined Patent Publication No.
Japanese Patent No. 313019 discloses an artificial syrup having good appearance and thickening stability by mixing a resin powder obtained by spray-drying a crosslinked polymer obtained by emulsion polymerization into an acrylic syrup to prevent the occurrence of cracks during molding. An acrylic premix for marble is disclosed. Further, Japanese Patent Laid-Open No. 7-1
No. 88505 discloses an acrylic premix for artificial marble having a stone pattern, in which kneading properties and moldability are improved by blending inorganic powder-containing resin particles having a specific oil absorption and swelling degree. Have been.

[0004]

However, Japanese Patent Application Laid-Open No. 5-3
In order to increase the viscosity of the acrylic syrup using a resin powder as disclosed in JP-A-2720 and JP-A-6-298883, a large amount of resin powder is required, which increases the production cost. In addition, there is a problem that productivity is reduced due to a long time required for thickening.

[0005] Further, even in an acrylic premix disclosed in JP-A-6-313019 or JP-A-7-188505, it is necessary to increase the viscosity to a level at which hot press molding is possible. However, there is a problem that aging of the premix for a long time (about 24 hours) is required. Further, in the acrylic premix disclosed in JP-A-7-188505, the resin particles containing the inorganic filler constituting the stone pattern swell during aging, and the boundary between the resin particles and the matrix is blurred. It has a problem that it is difficult to obtain a clear marbled artificial marble because it is easy.

An object of the present invention is to provide an acrylic premix having a short thickening time, excellent handleability and moldability, and a stone-grained acrylic artificial marble having a clear surface appearance.

[0007]

Means for Solving the Problems As a result of studying the above problems, the present inventors have found that the acrylic syrup contains an inorganic filler, an inorganic filler-containing resin particle, and a specific polymer powder. Acrylic premixes that increase in viscosity over time, have excellent handleability and moldability, and are then heated and press-cured to produce a stone-grained acrylic artificial marble with a clear surface appearance. The present inventors have found out what can be obtained and completed the present invention.

That is, the present invention provides an acrylic syrup comprising methyl methacrylate or a monomer mixture containing the same as a main component (a), and polymethyl methacrylate or a polymer containing a methyl methacrylate as a main component (b). (A), an inorganic filler (B), an inorganic filler-containing resin particle (C), a bulk density in the range of 0.1 to 0.7 g / ml, and an oil absorption of linseed oil of 60 to 200 ml. /
The present invention relates to an acrylic premix containing a non-crosslinked polymer powder (D) having a swelling degree of 16 times or more with respect to methyl methacrylate in the range of 100 g, and heating the acrylic premix by heating. The present invention relates to a stone-grained acrylic artificial marble obtained by pressure curing.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The acrylic syrup (A) used in the acrylic premix of the present invention is methyl methacrylate or a monomer mixture (a) containing the same as a main component, and polymethyl methacrylate or It is composed of a polymer (b) containing methyl methacrylate as a main component.

The methyl methacrylate constituting the acrylic syrup or the monomer mixture (a) containing the same as a main component preferably contains methyl methacrylate in an amount of 50 to 50%.
It is an unsaturated monomer or an unsaturated monomer mixture containing 100% by weight. The content of the component (a) 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 the acrylic premix Considering physical properties such as mechanical strength when using as a raw material of acrylic artificial marble, 3
A range of 0 to 90% by weight is preferred. This is because when the content of the component (a) is 30% by weight or more, the syrup has a low viscosity, so that the handleability is improved, and the content of the component (a) is 90% by weight or less. By doing so, the shrinkage rate during curing tends to decrease. It is more preferably in the range of 40 to 85% by weight, and still more preferably in the range of 50 to 80% by weight.

Examples of the monomer other than methyl methacrylate used in the component (a) include (meth) acrylic acid esters having 1 to 20 carbon atoms, cyclohexyl (meth) acrylate and glycidyl (meth).
Acrylate, hydroxyalkyl (meth) acrylate, (meth) acrylic acid, metal (meth) acrylate,
Fumaric acid, fumaric acid ester, maleic acid, maleic acid ester, aromatic vinyl, vinyl acetate, (meth) acrylamide, (meth) acrylonitrile, vinyl chloride,
Monofunctional monomers such as maleic anhydride, 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-dimethylolpropanedi (meth) acrylate, 2,2-dimethylolpropanedi (meth) acrylate , Trimethylolethanetri (meth) acrylate, trimethylolpropanetri (meth) acrylate, tetramethylolmethanetri (meth) acrylate, tetramethylolmethanedi (meth) acrylate, neopentylglycoldi (meth)
Acrylates and polyfunctional esters of (meth) acrylic acid with polyhydric alcohols such as polyethylene glycol, polypropylene glycol, pentaerythritol and dipentaerythritol, and polyfunctional monomers such as divinylbenzene, triaryl isocyanurate and aryl methacrylate Body. These can be used alone or in combination of two or more as necessary.

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

In particular, neopentyl glycol dimethacrylate is preferred as a polyfunctional monomer in that a molded article 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,
It is preferable that the content of the monomer other than methyl methacrylate in the component (a) be 50% by weight or more.

The polymethyl methacrylate or the polymer (b) containing methyl methacrylate as a main component, which constitutes the acrylic syrup used in the acrylic resin composition of the present invention, preferably contains 50 methyl methacrylate units.
It is an acrylic polymer contained in the range of 100 to 100% by weight. The content of the component (b) in the acrylic syrup is not particularly limited, but the workability when using the acrylic resin composition of the present invention as an acrylic premix, and the acrylic premix Is preferably in the range of 10 to 70% by weight in consideration of physical properties such as mechanical strength when using as a raw material of acrylic artificial marble. It is more preferably in the range of 15 to 60% by weight, and still more preferably 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. However, the component (b) should be considered in consideration of the fluidity of the obtained resin composition and the mechanical strength of the molding material. When added, the weight average molecular weight is 15,000
It is preferably in the range of ~ 300,000. More preferably, it is in the range of 25,000 to 250,000.

As the components other than the methyl methacrylate used in the component (b), the monomers used in the component (a) can be applied as they are, and two or more types are used in combination. be able to. 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, and a suspension polymerization method.

The acrylic syrup used in the acrylic resin composition of the present invention may be one obtained by dissolving the above component (b) in the above component (a) or partially polymerizing the above component (a), The product obtained by producing the component (b), the product obtained by further adding the component (a) to the partially polymerized product, or the product obtained by adding the component (b) to the partially polymerized product may be used.

The inorganic filler (B) used in the acrylic premix of the present invention is used for imparting excellent texture and heat resistance to the obtained artificial marble.
10 parts by weight of acrylic syrup (A)
It is preferably used in the range of 0 to 400 parts by weight. This is because when the used amount of the inorganic filler is 100 parts by weight or more, the texture and heat resistance of the obtained molded product are good, and when the used amount of the inorganic filler 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 (B), an inorganic filler such as aluminum hydroxide, silica, fused silica, calcium carbonate, barium sulfate, titanium oxide, calcium phosphate, talc, clay, glass powder, etc. is used as required. can do. In particular, it is preferable to use one or more selected from aluminum hydroxide, silica, fused silica, and glass powder as the inorganic filler since the resulting artificial marble tends to have a better appearance.

The inorganic filler-containing resin particles (C) used in the acrylic premix of the present invention are used to impart a stone pattern to the resulting acrylic artificial marble.

The amount of the inorganic filler-containing resin particles (C) of the present invention is not particularly limited, but may be in the range of 10 to 200 parts by weight based on 100 parts by weight of the acrylic syrup (A). preferable. More preferably, 20 to 150
It is in the range of parts by weight. This means that when the blending amount of the inorganic filler-containing resin particles (C) is 10 parts by weight or more, a stone pattern with good designability is obtained, and when the blending amount is 200 parts by weight or less, the kneading property at the time of producing a premix is obtained. Is likely to be good.

The resin constituting the inorganic filler-containing resin particles (C) may be any resin as long as it does not dissolve in methyl methacrylate, and examples thereof include a crosslinked acrylic resin, a crosslinked polyester resin, and a crosslinked styrene resin. A crosslinked acrylic resin is preferable because artificial marble having a high affinity with the syrup (A) and a beautiful appearance can be obtained. The crosslinked acrylic resin may contain polymethyl methacrylate or a non-crosslinked acrylic polymer containing methyl methacrylate as a main component.

The inorganic filler constituting the inorganic filler-containing resin particles (C) is preferably used in an amount of 50 to 80% by weight in the component (C). This is because when the amount of the inorganic filler used is 50% by weight or more, the texture and heat resistance of the obtained molded article are good, and the amount of the inorganic filler used is 8%.
If the content is 0% by weight or less, a molded product having high strength tends to be obtained.

Examples of the inorganic filler include aluminum hydroxide, silica, fused silica, calcium carbonate, barium sulfate, titanium oxide, calcium phosphate, talc, clay,
An inorganic filler such as glass powder can be used as needed. In particular, it is preferable to use one or more selected from aluminum hydroxide, silica, fused silica, and glass powder as the inorganic filler since the resulting artificial marble tends to have a better appearance.

The method for producing the inorganic filler-containing resin particles (C) is not particularly limited. For example, a resin molded product containing an inorganic filler obtained by polymerization and curing by a hot press method, a casting method, or the like is pulverized. There is a method of classifying by sieving. For example, those obtained by crushing and classifying acrylic artificial marble can be suitably used.

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

The polymer powder (D) used in the acrylic premix of the present invention is used as a thickener, and is used to impart a clear grain pattern to the resulting acrylic artificial marble. What is used. This is because the use of the polymer powder (D) allows the acrylic premix of the present invention to increase the viscosity immediately after the completion of kneading of the constituent components without the need for an aging period. It is considered that blurring at the boundary between the resin particles and the matrix (the interface between the stones) due to the swelling of (1) is suppressed.

The amount of the polymer powder (D) of the present invention is not particularly limited, but is preferably in the range of 0.1 to 100 parts by weight based on 100 parts by weight of the acrylic syrup (A). More preferably, it is in the range of 1 to 80 parts by weight. This is because in the case of 0.1 part by weight or more, the viscosity of the premix becomes good, and it becomes easy to obtain an acrylic artificial marble with a clear stone pattern, and in the case of 100 parts by weight or less, the premix is produced. This is because kneading properties and workability tend to be good.

The polymer powder (D) used in the acrylic premix of the present invention has a bulk density of 0.1 to 0.7 g /
ml and the oil absorption of linseed oil is 60-2.
It is necessary to be a non-crosslinked polymer powder having a swelling degree of 16 times or more with respect to methyl methacrylate in the range of 00 ml / 100 g.

This means that the bulk density of the polymer powder (D) is 0.
In the case of 1 g / ml or more, the polymer powder is hardly scattered, so that the yield at the time of the production becomes good, and the powder when adding and mixing the polymer powder to the acrylic syrup is reduced. This is because the workability is improved, and when the amount is 0.7 g / ml or less, a sufficient thickening effect can be obtained with a small amount of the polymer powder used. This is because a short time is required, so that the productivity is improved and the cost is also advantageous. Preferably, it is in the range of 0.15 to 0.65 g / ml, more preferably 0.2 to 0.5 g / ml.
Range.

Further, by setting the oil absorption of the polymer powder (D) to linseed oil at 60 ml / 100 g or more, a sufficient thickening effect can be obtained with a small amount of the polymer powder used, and further increased. This is because the viscosity can be shortened in a short time, so that the productivity is improved and the cost is advantageous.
When the content is not more than 00 ml / 100 g, the dispersibility of the polymer powder in the acrylic syrup is good. Therefore, when producing an acrylic premix from the acrylic resin composition containing the polymer powder and the acrylic syrup, This is because the kneading property becomes better. Preferably, 7
It is in the range of 0 to 180 ml / 100 g, and more preferably in the range of 80 to 140 ml / 100 g.

Further, when the degree of swelling of the polymer powder (D) with respect to methyl methacrylate is 16 times or more, the effect of thickening the acrylic syrup becomes sufficient. More preferably, it is 20 times or more.

Further, when the polymer powder (D) is a non-crosslinked polymer powder, a sufficient thickening effect can be obtained in a short time, the sharpness of the grain pattern is improved, and the grain pattern is improved. This is because unevenness tends to disappear. This is considered to be due to the fact that a part or all of the non-crosslinked polymer powder is immediately dissolved after swelling in the acrylic syrup. In consideration of the balance between the thickening effect and the thickening time, the weight average molecular weight of the polymer powder (D) composed of a non-crosslinked polymer is preferably 100,000 or more. It is more preferably in the range of 100,000 to 3.5 million, and still more preferably 3 to 3.5 million.
In the range of 100,000 to 3,000,000, most preferably 50 to 2
It is in the range of one million. In addition, the non-crosslinked polymer powder is a polymer powder in which at least the surface layer portion is composed of a non-crosslinked polymer.

The average particle size of the polymer powder (D) is not particularly limited, but is preferably in the range of 1 to 250 μm. This is because when the average particle diameter is 1 μm or more, the handleability of the polymer powder tends to be good, and when the average particle diameter is 250 μm or less, the appearance of the obtained molding material tends to be good. More preferably, it is in the range of 3 to 150 μm, and still more preferably, it is in the range of 5 to 130 μm.

As the polymer constituting the polymer powder (D), various polymers can be appropriately selected and used as needed.
Although not particularly limited, an acrylic polymer is preferable in consideration of the appearance and the like of the obtained acrylic artificial marble.

The constituents of the polymer powder (D) include, for example, an alkyl (meth) acrylate 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, fumarate ester, maleic acid, maleate ester, aromatic vinyl,
Examples thereof include vinyl acetate, (meth) acrylamide, (meth) acrylonitrile, vinyl chloride, and maleic anhydride. These may be polymerized alone if necessary, or may be copolymerized in combination of two or more, but taking into account the affinity with the monomer components constituting the acrylic syrup. (Meth) acrylic monomers are preferred.

The polymer powder (D) used in the present invention is a so-called core / shell composed of a core phase and a shell phase having different chemical compositions, structures, molecular weights, etc. of the polymers forming them. A polymer powder having a shell structure can also be used. In this case, the core phase may be a non-crosslinked polymer or a crosslinked polymer, but the shell phase needs to be a noncrosslinked polymer.

The constituents of the core phase and the shell phase of the polymer powder include, for example, an alkyl (meth) acrylate 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 ester, aromatic vinyl, vinyl acetate, (meth) acrylic amide, (meth) Acrylonitrile, vinyl chloride, maleic anhydride and the like can be mentioned. These may be polymerized alone if necessary, or may be copolymerized by using two or more kinds in combination.However, in order to increase the affinity with the monomer component constituting the acrylic syrup, a shell is used. The phase is preferably based on methyl methacrylate. When crosslinking the core phase, 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-dimethylolpropanedi (meth) acrylate, 2,2-
Dimethylolpropanedi (meth) acrylate, trimethylolethanetri (meth) acrylate, trimethylolpropanetri (meth) acrylate, tetramethylolmethanetri (meth) acrylate, tetramethylolmethanedi (meth) acrylate, neopentylglycoldi ( (Meth) acrylate, and polyfunctionality such as polyhydric ester of (meth) acrylic acid with polyhydric alcohol such as polyethylene glycol, polypropylene glycol, pentaerythritol, dipentaerythritol, divinylbenzene, triaryl isocyanurate, aryl methacrylate, etc. Monomers can be used as constituent components, and these can be used alone or in combination of two or more.

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

The acrylic premix of the present invention may contain, if necessary, benzoyl peroxide, lauroyl peroxide, t-butyl hydroperoxide, cyclohexanone peroxide, methyl ethyl peroxide, t-butyl peroxy octoate, t-butyl peroxybenzoate, dicumyl peroxide,
Hardeners such as organic peroxides and azo compounds such as 1,1-bis (t-butylperoxy) 3,3,5-trimethylcyclohexane and azobisisobutyronitrile; reinforcing materials such as glass fibers and carbon fibers And various additives such as a colorant and a low-shrinkage agent. However, by adding zinc stearate, a molded article having more excellent gloss can be obtained. The amount of zinc stearate is not particularly limited, but is preferably in the range of 0.05 to 4.0 parts by weight based on 100 parts by weight of the acrylic premix. More preferably, it is in the range of 0.1 to 2.0 parts by weight.

The method of mixing the constituent components for obtaining the acrylic premix of the present invention is not particularly limited as long as it is a method capable of efficiently mixing a high-viscosity substance. For example, a kneader, a mixer, a roll, an 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 into a mold and heating and curing the mixture. Specific examples of the heat and pressure curing include a compression molding method, an injection molding method, and an extrusion molding method, but are not particularly limited.

The acrylic premix of the present invention is characterized in that it has no stickiness, is easy to handle, and is easy to measure. In addition, the viscosity increases in a very short time after the completion of kneading, so that the aging period is short. It is unnecessary and has excellent productivity. Furthermore, the acrylic premix of the present invention is suitable for high-temperature molding. By heating and curing the mixture, a stone-grain artificial marble having a clear stone pattern and excellent design properties can be obtained.

[0044]

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

Physical properties of polymer powder Average particle diameter: Measured using a laser diffraction / scattering type particle size distribution analyzer (LA-910, manufactured by HORIBA, Ltd.).

Bulk density: JIS R 6126- 1970
It measured based on.

Oil absorption: JIS K 5101-1991
The end point was taken immediately before the putty-like mass suddenly softened with the last drop of linseed oil.

Weight average molecular weight: Measured value by GPC method (in terms of polystyrene) Swelling degree: The polymer powder was charged into a 100 ml graduated cylinder, patted several times, packed in 5 ml, and then cooled to 10 ° C. or less methyl methacrylate. Is added so that the total amount becomes 100 ml, and the mixture is rapidly stirred so that the whole becomes uniform. Thereafter, the graduated cylinder was kept in a thermostat at 25 ° C. for 1 hour, and the volume of the polymer powder layer after swelling was determined and indicated by the ratio to the volume before swelling (5 ml).

Method for measuring physical properties of acrylic syrup Weight average molecular weight: measured by GPC method.

(1) Production Example of Polymer Powder (P-1) In a reactor equipped with a cooling pipe, a thermometer, a stirrer, a dropping device, and a nitrogen introduction pipe, 925 parts of pure water, sodium alkyldiphenyl ether disulfonate were added. 5 parts (manufactured by Kao Corporation, trade name: Perex SS-H) and 1 part of potassium persulfate were charged and heated to 70 ° C. while stirring under a nitrogen atmosphere. A mixture consisting of 500 parts by weight of methyl methacrylate and 5 parts of sodium dialkylsulfosuccinate (trade name: Perex OT-P, manufactured by Kao Corporation) was added dropwise over 3 hours. The emulsion polymerization was completed by raising the temperature and holding for 1 hour to obtain an emulsion.

The obtained emulsion was spray-dried using an L-8 type spray-drying device manufactured by Okawara Kakoki Co., Ltd. to obtain a thermoplastic polymer powder (P-1) having an average particle size of 30 μm. The obtained non-crosslinked polymer powder (P-1) was completely dissolved in methyl methacrylate, and had a swelling degree of 20 or more. Table 1 shows other physical property values.

(2) Production Example of Polymer Powder (P-2) In a reactor equipped with a cooling pipe, a thermometer, a stirrer, a dropping device, and a nitrogen introduction pipe, 925 parts of pure water, sodium alkyldiphenylether disulfonate were added. 5 parts (manufactured by Kao Corporation, trade name Perex SS-H) and 0.25 parts of potassium persulfate were charged and heated to 70 ° C. while stirring under a nitrogen atmosphere. To this, 149.85 parts by weight of methyl methacrylate and 0.1 part of 1,3-butylene glycol dimethacrylate were added.
A mixture comprising 15 parts by weight of 5 parts of sodium dialkylsulfosuccinate (manufactured by Kao Corporation, trade name: Perex OT-P) was added dropwise over 1.5 hours, and then held for 1 hour.
Subsequently, 350 parts by weight of methyl methacrylate was added dropwise over 3.5 hours, and then maintained for 1 hour. After the temperature was raised to 80 ° C., the temperature was maintained for 1 hour to complete the emulsion polymerization to obtain an emulsion.

The obtained emulsion was spray-dried using an L-8 type spray dryer manufactured by Okawara Kakoki Co., Ltd., and had an average particle diameter of 20 μm, a core phase of a crosslinked polymer, and a shell phase of a non-crosslinked polymer. A polymer powder (P-2) having a certain core / shell structure was obtained. The swelling degree of the obtained polymer powder having a core / shell structure was 20 or more. Table 1 shows other physical property values.

(3) Production Example of Polymer Powder (P-3) In a reactor equipped with a cooling pipe, a thermometer, a stirrer, a dropping device, and a nitrogen introduction pipe, 925 parts of pure water, polyoxyethylene nonylphenyl ether were added. 5 parts of (Emulgen 930, manufactured by Kao Corporation) and 1.5 parts of potassium persulfate were charged and heated to 70 ° C. while stirring under a nitrogen atmosphere. Then, 500 parts of methyl methacrylate and sodium dialkyl sulfosuccinate (trade name: Perex OT, manufactured by Kao Corporation)
-P) A mixture consisting of 10 parts was added dropwise over 3 hours, and the resulting mixture was maintained for 1 hour, further heated to 80 ° C and maintained for 1 hour to complete the emulsion polymerization to obtain an emulsion.

The obtained emulsion was spray-dried using an L-8 type spray dryer manufactured by Okawara Kakoki Co., Ltd. to obtain a non-crosslinked polymer powder (P-3) having an average particle diameter of 20 μm. The obtained (P-3) was completely dissolved in methyl methacrylate, and had a swelling degree of 20 or more. Table 1 shows other physical property values.
Shown in

(4) Production Example of Polymer Powder (P-4) In a reactor equipped with a cooling tube, a thermometer, a stirrer, a dropping device, and a nitrogen introduction tube, 925 parts of pure water, sodium alkyldiphenyl ether disulfonate were added. 5 parts (manufactured by Kao Corporation, trade name: Perex SS-H) and 0.15 part of potassium persulfate were charged and heated to 70 ° C. while stirring under a nitrogen atmosphere. A mixture consisting of 500 parts of methyl methacrylate and 5 parts of sodium dialkylsulfosuccinate (trade name: Perex OT-P, manufactured by Kao Corporation) was added dropwise over 3 hours, and the mixture was maintained for 1 hour, and further heated to 80 ° C. The emulsion polymerization was terminated by heating and holding for 1 hour to obtain an emulsion.

The obtained emulsion was spray-dried using an L-8 type spray-drying apparatus manufactured by Okawara Kakoki Co., Ltd. to obtain a non-crosslinked polymer powder (P-4) having an average particle diameter of 20 μm.
The obtained (P-4) was completely dissolved in methyl methacrylate, and had a swelling degree of 20 or more. Table 1 shows other physical property values.

(5) Production Example of Polymer Powder (P-5) In a reactor equipped with a cooling tube, a thermometer, a stirrer, a dropping device, and a nitrogen inlet tube, 925 parts of pure water, sodium alkyldiphenyl ether disulfonate were added. 5 parts (manufactured by Kao Corporation, trade name: Perex SS-H) and 0.05 part of potassium persulfate were charged and heated to 70 ° C. while stirring under a nitrogen atmosphere. A mixture consisting of 500 parts of methyl methacrylate and 5 parts of sodium dialkylsulfosuccinate (trade name: Perex OT-P, manufactured by Kao Corporation) was added dropwise over 3 hours, and the mixture was maintained for 1 hour, and further heated to 80 ° C. The emulsion polymerization was terminated by heating and holding for 1 hour to obtain an emulsion.

The obtained emulsion was spray-dried using an L-8 type spray dryer manufactured by Okawara Kakoki Co., Ltd. to obtain a non-crosslinked polymer powder (P-5) having an average particle size of 20 μm.
The obtained (P-5) was completely dissolved in methyl methacrylate, and the swelling degree was 20 or more. Table 1 shows other physical property values.

(6) Production Example of Polymer Powder (P-6) In a reactor equipped with a cooling pipe, a thermometer, a stirrer, a dropping apparatus, and a nitrogen introduction pipe, 925 parts of pure water, sodium alkyldiphenyl ether disulfonate were added. (Kao Corporation, trade name: Perex SS-H) (5 parts) and potassium persulfate (2.5 parts) were charged and heated to 80 ° C. while stirring under a nitrogen atmosphere. Then, 500 parts of methyl methacrylate, 3 parts of n-dodecyl mercaptan and sodium dialkylsulfosuccinate (trade name Perex OT-P, manufactured by Kao Corporation)
After dropping the mixture consisting of 5 parts over 3 hours, the mixture was kept for 2 hours to terminate the emulsion polymerization, and an emulsion was obtained.

The obtained emulsion was spray-dried using an L-8 type spray dryer manufactured by Okawara Kakoki Co., Ltd. to obtain a non-crosslinked polymer powder (P-6) having an average particle diameter of 20 μm.
The obtained (P-6) was completely dissolved in methyl methacrylate, and the swelling degree was 20 or more. Table 1 shows other physical property values.

(7) Production Example of Polymer Powder (P-7) In a reactor equipped with a cooling pipe, a thermometer, a stirrer, a dropping apparatus, and a nitrogen introduction pipe, 925 parts of pure water, sodium alkyldiphenyl ether disulfonate were added. 5 parts (manufactured by Kao Corporation, trade name Perex SS-H) and 0.25 parts of potassium persulfate were charged and heated to 70 ° C. while stirring under a nitrogen atmosphere. To this, 497.5 parts of methyl methacrylate, 1,
A mixture of 2.5 parts of 3-butylene glycol dimethacrylate and 5 parts of sodium dialkyl sulfosuccinate (trade name: Perex OT-P, manufactured by Kao Corporation) was added dropwise over 3 hours, and the mixture was kept for 1 hour, and further retained for 80 hours. The emulsion polymerization was completed by raising the temperature to 0 ° C and maintaining the temperature for 1 hour to obtain an emulsion.

The obtained emulsion was spray-dried using an L-8 type spray dryer manufactured by Okawara Kakoki Co., Ltd. to obtain a crosslinked polymer powder (P-7) having an average particle size of 18 μm. The swelling degree of the obtained (P-7) was 20 or more. Table 1 shows other physical property values.

(8) Production Example of Polymer Powder (P-8) In a reactor equipped with a cooling pipe, a thermometer, a stirrer, and a nitrogen introduction pipe, 800 parts of pure water and polyvinyl alcohol (saponification degree 8) were added.
After dissolving 1 part of 8% and a polymerization degree of 1000), a monomer solution in which 400 parts of methyl methacrylate and 0.5 part of azobisisobutyronitrile are dissolved is added, and 1 part is stirred under a nitrogen atmosphere. The temperature is raised to 80 ° C in a time
Heated for hours. Then, after heating to 90 ° C. and heating for 2 hours,
The mixture was further heated to 120 ° C. to distill off residual monomers together with water to obtain a slurry, thereby completing the suspension polymerization. The obtained slurry was filtered and washed, and then dried with a hot air dryer at 50 ° C. to obtain polymethyl methacrylate (P-8) having an average particle size of 88 μm. The degree of swelling of the obtained (P-8) was 1.
It was 2. Table 1 shows other physical property values.

(9) Production Example of Polymethyl Methacrylate (B-1) in Acrylic Syrup A reactor equipped with a cooling pipe, a thermometer, a stirrer, and a nitrogen introduction pipe was charged with 800 parts of pure water and polyvinyl alcohol (saponified). Degree 8
After dissolving 1 part of 8% and a polymerization degree of 1000), a monomer solution in which 400 parts of methyl methacrylate, 2 parts of normal dodecyl mercaptan and 2 parts of azobisisobutyronitrile are dissolved is added, and the mixture is placed under a nitrogen atmosphere. The temperature was raised to 80 ° C. in 1 hour with stirring, and the mixture was heated as it was for 2 hours. afterwards,
After heating to 90 ° C. and heating for 2 hours, the mixture was further heated to 120 ° C. to distill off residual monomers together with water to obtain a slurry, thereby completing suspension polymerization. After filtering and washing the obtained slurry, it was dried with a hot air dryer at 50 ° C., and the average particle diameter was 93 μm.
Of polymethyl methacrylate (B-1) was obtained. The weight average molecular weight of the obtained (B-1) was 40,000. Table 1 shows other physical property values.

(10) Production Example of Resin Particles Containing Inorganic Filler An acrylic resin comprising 69% of methyl methacrylate, 2% of ethylene glycol dimethacrylate, and 29% of polymethyl methacrylate (B-1) obtained in the above production example (9). To 100 parts of syrup, 2.0 parts of t-butyl peroxybenzoate (trade name: Perbutyl Z, manufactured by NOF CORPORATION) as a curing agent, and 0.1 part of zinc stearate as an internal release agent.
After adding 5 parts and inorganic pigment 0.25 parts, 200 parts of aluminum hydroxide (manufactured by Showa Denko K.K., trade name: Heidilite H-310) was added as an inorganic filler, and the above production example (1) 30 parts of the polymer powder (P-1) obtained in the above was added and kneaded with a kneader for 10 minutes to obtain an acrylic premix. Next, 200m of acrylic premix
The m-square flat mold was filled and heated and cured for 10 minutes at a mold temperature of 130 ° C. and a pressure of 100 kg / cm ² to obtain an acrylic artificial marble having a thickness of 10 mm. The obtained acrylic artificial marble was pulverized with a crusher to obtain inorganic filler-containing resin particles.

[0067]

[Table 1]

Example 1 Methyl methacrylate 48
%, Neopentyl glycol dimethacrylate 27%,
And 100 parts of an acrylic syrup composed of 25% of polymethyl methacrylate (B-1) obtained in the above Production Example (9), as a curing agent, t-butylperoxybenzoate (trade name: Perbutyl Z, manufactured by NOF Corporation) ) 3.0 parts,
After adding 0.5 part of zinc stearate as an internal mold release agent, 150 parts of aluminum hydroxide (trade name: HYGILITE H-310, manufactured by Showa Denko KK) as an inorganic filler and the above-mentioned Production Example (10) A total of 70 parts of the black and white inorganic filler-containing resin particles prepared by the above method were added, and the polymer powder (P-
1) 30 parts were added and kneaded with a kneader for 10 minutes. The obtained acrylic premix had no stickiness immediately after kneading and had good handleability.

Next, the obtained acrylic premix was filled into a 200 mm square flat mold and heated and cured for 10 minutes at a mold temperature of 130 ° C. and a pressure of 100 kg / cm ² . A stone-like acrylic artificial marble having a thickness of 10 mm was obtained. The surface of the obtained molded article was extremely high, had a very clear stone pattern, had no unevenness in the stone pattern, and was a good grain-like artificial marble having an excellent appearance and excellent appearance. .

Example 2 Acrylic syrup was composed of 48% of methyl methacrylate, 14% of neopentyl glycol dimethacrylate, 13% of ethylene glycol dimethacrylate, and polymethyl methacrylate (B-1) obtained in the above Production Example (9). The acrylic premix obtained in the same manner as in Example 1 except that the acrylic syrup was composed of 25% had no stickiness immediately after kneading and had good handleability.

Next, the obtained acrylic premix was heated and pressed in the same manner as in Example 1 to obtain a stone-grain artificial marble having an extremely high surface gloss and a very clear stone pattern. It was a stone-grain-like artificial marble with excellent appearance and excellent appearance with no unevenness in the stone pattern.

Example 3 An acrylic prepolymer obtained in the same manner as in Example 2 except that 30 parts of the polymer powder (P-2) obtained in Production Example 2 was added as a thickener. The mix had no stickiness immediately after kneading and had good handleability.

Next, the obtained acrylic premix was heated and pressed in the same manner as in Example 2 to obtain a stone-grain artificial marble having an extremely high surface gloss and a very clear stone pattern. It was a stone-grain-like artificial marble with excellent appearance and excellent appearance with no unevenness in the stone pattern.

Comparative Example 1 An acrylic premix was obtained in the same manner as in Example 2 except that 30 parts of the polymer powder (P-7) obtained in Production Example (7) was added as a thickener. Was. The obtained acrylic premix required 16 hours or more to thicken, was sticky, and was poor in handleability.

Next, the obtained acrylic premix was heated and pressed in the same manner as in Example 2 to obtain a stone-grain artificial marble having a slightly blurred grain pattern. The pattern was uneven and the design was poor.

Example 4 Acrylic syrup comprising 48% of methyl methacrylate, 27% of ethylene glycol dimethacrylate, and 25% of polymethyl methacrylate (B-1) obtained in Production Example (9). The acrylic premix obtained in the same manner as in Example 1 except for the above, had no stickiness immediately after kneading and had good handleability.

Next, the obtained acrylic premix was heated and pressed in the same manner as in Example 1 to obtain a stone-grain artificial marble having a high surface gloss and a very clear stone-grain pattern. It was a stone-grain tone artificial marble with excellent appearance and excellent appearance with no unevenness in the stone pattern.

Example 5 Internal release agent was Aerosol O
The acrylic premix obtained in the same manner as in Example 2 except that T-100 (manufactured by Mitsui Cyminad Co., Ltd.) was 0.5 part, had no stickiness immediately after kneading and had good handleability.

Then, the obtained acrylic premix was heated and pressed in the same manner as in Example 2 to obtain a stone-grain artificial marble having a high surface gloss and a very clear stone-grain pattern. It was a stone-grain artificial marble with excellent appearance and excellent appearance without any unevenness in the stone pattern.

Comparative Example 2 An acrylic premix was obtained in the same manner as in Example 2, except that 30 parts of the polymer powder (P-8) obtained in Production Example (8) was added as a thickener. Was. The obtained acrylic premix required 16 hours or more to thicken, was sticky, and was poor in handleability.

Then, the obtained acrylic premix was heated and pressed in the same manner as in Example 2 to obtain a stone-grain-like artificial marble having a slightly blurred stone-grain pattern. The pattern was uneven and the design was poor.

Example 6 Methyl methacrylate 48
%, Neopentyl glycol dimethacrylate 15%,
Ethylene glycol dimethacrylate 2%, and polymethyl methacrylate (B-1) obtained in Production Example (9) above
To 100 parts of an acrylic syrup consisting of 35%, 1,1-bis (t-butylperoxy) 3,3
After adding 2.5 parts of 5-trimethylcyclohexane (trade name: Perhexa 3M, manufactured by NOF CORPORATION) and 0.5 parts of zinc stearate as an internal release agent, aluminum hydroxide (showa denko ( 170 parts of trade name (Heidilite H-310, trade name) and 70 parts of the black and white inorganic filler-containing resin particles produced by the method of the above-mentioned Production Example (10) are added in total, and the above-mentioned Production Example (1) is added. )), And 25 parts of the polymer powder (P-1) obtained in
The mixture was kneaded for an minute to obtain an acrylic premix. The obtained acrylic premix had no stickiness immediately after kneading and had good handleability. Table 2 shows the evaluation results of thickening.
Shown in

Next, the obtained acrylic premix was filled into a 200 mm square flat mold, and the mixture was cured by heating and pressing at a mold temperature of 130 ° C. and a pressure of 100 kg / cm ² for 10 minutes. A stone-like acrylic artificial marble having a thickness of 10 mm was obtained. The obtained stone-grain artificial marble has an extremely high surface gloss, has a very clear stone-grain pattern, has no unevenness in the stone-grain pattern, and has a very good design and good appearance. Met.

Examples 7 and 8 The acrylic premix obtained in the same manner as in Example 1 except that polymer powders (P-3) and (P-4) were used as thickeners,
Immediately after kneading, there was no stickiness and the handleability was good.

Then, the obtained acrylic premix was heated and pressed in the same manner as in Example 1 to obtain a stone-grain artificial marble having an extremely high surface gloss and a very clear stone pattern. It was a stone-grain artificial marble with excellent appearance and excellent appearance with no unevenness in the stone pattern.

[Examples 9 to 10] An acrylic premix was obtained in the same manner as in Example 1 except that polymer powders (P-5) to (P-6) were used as thickeners. This acrylic premix was aged at room temperature to obtain a premix with no stickiness and good handleability, but it took 16 hours or more to thicken.

Next, the obtained acrylic premix was heated and pressed in the same manner as in Example 1 to obtain a stone-grain artificial marble having an extremely high surface gloss and a clear stone-grain pattern. It was a stone-grained artificial marble that had good texture with no unevenness in the stone pattern.

Comparative Example 3 Methyl methacrylate 48
%, Neopentyl glycol dimethacrylate 14%,
13% of ethylene glycol dimethacrylate and the polymethyl methacrylate (B-
1) 3.0 parts of t-butyl peroxybenzoate (trade name: Perbutyl Z, manufactured by NOF CORPORATION) as a curing agent in 100 parts of an acrylic syrup composed of 25%, and 0.1 part of zinc stearate as an internal release agent. After adding 5 parts, aluminum hydroxide was used as an inorganic filler (Showa Denko KK)
200 parts of Heidilite H-310) and 100 parts of black and white inorganic filler-containing resin particles produced by the method of Production Example (10).
Kneaded for 0 minutes. The resulting acrylic premix,
Even after 20 hours or more after kneading, it was sticky and extremely poor in handling.

Next, the obtained acrylic premix was filled into a 200 mm square flat mold, and cured by heating and pressing at a mold temperature of 130 ° C. and a pressure of 100 kg / cm ² for 10 minutes. A stone-like acrylic artificial marble having a thickness of 10 mm was obtained. The obtained molded article had a blurred stone pattern, and had a very uneven stone pattern, and was very poor in design.

[0090]

[Table 2]

[0091]

[Table 3]

Thickening of premix A: Viscosity was increased immediately after kneading, and a premix with no stickiness and good handleability was obtained.

Good: A good premix without stickiness was obtained, but thickening required 16 hours or more.

Δ: It took 16 hours or more to thicken, and the obtained premix was sticky and poor in handleability.

X: Even after 20 hours or more after kneading, the premix was sticky and extremely poor in handleability.

Gloss of molded article A: Very high gloss.

○: High gloss.

Δ: There is gloss.

X: Low gloss.

The sharpness of the grain of the molded product A: extremely clear and very excellent in design.

：: Clear and excellent in design.

Δ: Stones are slightly blurred and poor in design.

X: The grain is fuzzy and very poor in design.

Uneven pattern of stone pattern of molded article A: There is no pattern unevenness at all, and the design is very excellent.

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

Δ: There is pattern unevenness, and the design is inferior.

X: The pattern unevenness was severe and the design was very poor.

[0108]

As is clear from the above examples, the acrylic premix of the present invention has good handleability and moldability, and has a clear stone pattern and excellent gloss by using this. Stone-grained acrylic artificial marble can be easily obtained and is industrially very useful.

──────────────────────────────────────────────────続 き Continued on front page (51) Int.Cl. ⁶ Identification code FI C04B 20:10) 111: 54

Claims (5)

[Claims] 1. An acrylic syrup (A) comprising methyl methacrylate or a monomer mixture (a) containing the same as a main component, and polymethyl methacrylate or a polymer (b) containing a methyl methacrylate as a main component. , An inorganic filler (B), an inorganic filler-containing resin particle (C), a bulk density in the range of 0.1 to 0.7 g / ml, and an oil absorption to linseed oil in the range of 60 to 200 ml / 100 g. An acrylic premix comprising a non-crosslinked polymer powder (D) having a swelling degree with respect to methyl methacrylate of 16 times or more. 2. A monomer mixture (a) containing a polyfunctional (meth) acrylate monomer,
The acrylic premix according to claim 1. 3. The acrylic premix according to claim 2, wherein the polyfunctional (meth) acrylate monomer is neopentyl glycol dimethacrylate. 4. The acrylic premix according to claim 1, further comprising zinc stearate. 5. A stone-like acrylic artificial marble obtained by heating and pressure curing the acrylic premix according to claim 1.