JP3486537B2 - Acrylic resin composition, premix, SMC or BMC, and method for producing artificial marble - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an acrylic resin composition having excellent moldability, an acrylic premix useful as a raw material for an acrylic artificial marble, low odor,
It has excellent handleability during high temperature molding and has a good viscosity increase.
The present invention relates to an acrylic SMC or BMC that is particularly useful as a raw material for an acrylic artificial marble, and a method for producing an acrylic artificial marble that has high productivity and good appearance.

[0002]

2. Description of the Related Art Acrylic artificial marble, which is an acrylic resin blended with an inorganic filler such as aluminum hydroxide, has various excellent functional characteristics such as excellent molding appearance, soft texture and weather resistance. Widely used for counters such as kitchen counters, vanities, waterproof pans, and other construction applications. These are generally produced by a method in which a so-called premix 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 and filling the premix into the mold. This has the drawback that the shape of the molded product is limited due to the problem of the sex.

In order to improve these drawbacks, SMC or BMC obtained by thickening resin syrup with a thickener is
Conventionally, studies have been made to manufacture an acrylic artificial marble by heating and pressing at a high temperature of 00 ° C. or higher.

For example, Japanese Patent Laid-Open No. 6-313019 discloses an acrylic BM in which aluminum hydroxide is mixed with acrylic syrup containing methyl methacrylate as a main component.
A method for producing artificial marble by heating and pressing C at a high temperature of 115 ° C. is disclosed.

[0005]

However, when an acrylic artificial marble is produced by such a method, since it is formed at a temperature higher than the boiling point of methyl methacrylate, vapor of methyl methacrylate is generated in the mold, resulting in a molded product. The surface is apt to be attacked by methylmethacrylate vapor, resulting in uneven gloss, and the problem of reduced gloss is likely to occur. Such a tendency becomes particularly remarkable when the curing temperature is increased to further increase the production rate.

Further, the acrylic SMC or BMC disclosed in the above publication has an odor peculiar to the acrylic monomer, and may cause discomfort during handling. This tendency becomes remarkable especially when these SMC or BMC are molded at a high temperature of 100 ° C. or higher.

Further, the acrylic SMC or BMC described in JP-A-6-313019 requires aging for a long time (24 hours or more) in order to increase the viscosity, resulting in low productivity. Have.

An object of the present invention is to obtain an acrylic resin composition having a glossy molding appearance and excellent molding processability,
Acrylic premixes useful as raw materials for acrylic artificial marble, acrylic SMCs or BMCs that are particularly useful as raw materials for acrylic artificial marbles that have little odor and are easy to handle during high-temperature molding processing, and have high productivity. It is an object of the present invention to provide a method for producing an acrylic artificial marble that is high and has a good appearance.

[0009]

Means for Solving the Problems As a result of studying the above-mentioned problems, the present inventors have found that the acrylic resin composition containing a (meth) acrylate having an ester group having a specific structure allows molding without uneven gloss. Appearance is obtained, acrylic resin composition excellent in molding processability, to find an acrylic premix useful as a raw material of acrylic artificial marble, further, by containing a thickener in this acrylic premix, Less odor,
Acrylic SMC or B, which is particularly useful as a raw material for acrylic artificial marble, which is easy to handle during high-temperature molding.
The present invention has been completed by discovering MC and a method for producing an acrylic artificial marble with high productivity and good appearance.

That is, the present invention contains a (meth) acrylate having an ester group having a cyclic ether structure, or a monomer mixture (a) containing the same, a polymethylmethacrylate or an acrylic polymer (b). An acrylic resin composition comprising: an acrylic premix containing the acrylic resin composition and an inorganic filler; and the acrylic premix and a thickener. The present invention relates to an acrylic SMC or BMC characterized by containing: and a method for producing an acrylic artificial marble, characterized in that the acrylic SMC or BMC is heated and pressure cured in a range of 100 to 150 ° C. It is a thing.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION A (meth) acrylate having an ester group having a cyclic ether structure, which is used as the component (a) constituting the acrylic resin composition of the present invention, or a (meth) acrylic system containing the same. The monomer mixture imparts excellent molding processability to the acrylic resin composition of the present invention, gives a molded article a molding appearance without gloss unevenness, and has little odor during high temperature molding, and imparts good handleability. It is a component for. The (meth) acrylate means methacrylate or acrylate.

The (meth) acrylate having an ester group having a cyclic ether structure used as the component (a) is not particularly limited, and examples thereof include glycidyl (meth) acrylate and tetrahydrofurfuryl (meth) acrylate. Can be mentioned. These may be used alone or in combination of two or more, if necessary, but tetrahydrofurfuryl (meth) acrylate is preferable from the viewpoint of odor.

The (meth) acrylate having an ester group having a cyclic ether structure is preferably used in the acrylic resin composition of the present invention in an amount of 5 to 90% by weight. This is because the use in this range tends to eliminate the gloss unevenness of the obtained molded product, and tends to reduce the odor during high temperature molding. The range is more preferably 10 to 85% by weight, still more preferably 15 to 80% by weight.

Other monomers used as the component (a) include, for example, (meth) acrylic acid ester having an alkyl group having 1 to 20 carbon atoms, cyclohexyl (meth) acrylate, and isobornyl (meth). ) Acrylate, glycidyl (meth) acrylate, hydroxyalkyl (meth) acrylate, benzyl (meth) acrylate, trifluoroethyl (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 may be mentioned. These may be used alone or in combination of two or more, if necessary, but a (meth) acrylic monofunctional monomer is preferable because the resulting molded article tends to have a good appearance. Of these, methyl methacrylate is particularly preferable.

These monofunctional monomers can be contained in the acrylic resin composition of the present invention in an amount of 40% by weight or less. The range is more preferably 35% by weight or less, and further preferably 30% by weight or less.

Further, when the acrylic resin composition of the present invention contains a polyfunctional monomer as the component (a),
It is preferable because the resulting molded article tends to have excellent strength, solvent resistance, heat resistance, dimensional stability and the like.

Examples of the polyfunctional monomer include ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, 1,3-butylene glycol di (meth) acrylate and 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 particular, the use of neopentyl glycol dimethacrylate and / or 1,3-butylene glycol dimethacrylate as the polyfunctional monomer tends to give a molded product having extremely excellent surface gloss, which is preferable. In this case, neopentyl glycol dimethacrylate and / or 1,3-butylene glycol dimethacrylate may be used in combination with another polyfunctional monomer.

The amount of these polyfunctional monomers used is not particularly limited, but in order to effectively obtain the above effects, they are used in the range of 1 to 50% by weight in the acrylic resin composition of the present invention. Is preferred. A more preferred range is 3 to 40% by weight, and a most preferred range is 5 to 30% by weight.

The component (b) constituting the acrylic resin composition of the present invention is polymethylmethacrylate or an acrylic copolymer.

The content of the component (b) 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 is used as an acrylic premix. Considering physical properties such as mechanical strength when used as a raw material for the artificial marble, the range of 10 to 90% by weight is preferable. The range is more preferably 15 to 85% by weight, and further preferably 20 to 80% 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 obtained resin composition 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 2,000,000. More preferably, 25,000-1,000,00
The range is 0, and the most preferable range is 30,000 to 6
It is 0,000.

As the constituent component used in the acrylic polymer as the component (b), for example, the above monofunctional monomer can be applied as it is. Two or more kinds of the constituents 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 components (a) and (b) used in the acrylic resin composition of the present invention may be those obtained by dissolving the component (b) in the component (a), or the component (a). The component (b), which is a polymer thereof, may be formed in the component (a) by partially polymerizing
The partially polymerized product may further contain the component (a), or the partially polymerized product may further contain the component (b).

The acrylic resin composition of the present invention can be used as an acrylic premix useful as a raw material for an acrylic artificial marble by further adding an inorganic filler and other additives as required. it can.

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 resulting molded product tends to have good texture and heat resistance, and when the amount is 400 parts by weight or less, the strength of the product is improved. This is because it tends to be possible to obtain a high molded product. More preferably 100 to 3
It is in the range of 00 parts by weight.

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.

Further, by blending the acrylic premix of the present invention with resin particles containing an inorganic filler, and molding the mixture, a granite-like artificial marble having a grain pattern can be obtained.

The blending 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 constituting 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 resin particles containing an inorganic filler 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, but 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, it is preferable to use inorganic filler-containing resin particles obtained by crushing and classifying acrylic artificial marble.

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 acrylic premix of the present invention can be used as an acrylic SMC or BMC by further containing a thickener. The thickener is not particularly limited and, for example, magnesium oxide powder, polymer powder or the like can be used, but the polymer powder is preferably used because the molded product tends to have excellent water resistance.

The polymer powder that can be used as the thickener is not particularly limited and can be appropriately selected as necessary. For example, the above-mentioned inorganic filler-containing resin particles can be used as the thickener. However, the bulk density is 0.1 to 0.
It is in the range of 7 g / ml, and the oil absorption amount for linseed oil is 6
It is preferable to use a non-crosslinked polymer powder having a swelling degree with respect to methyl methacrylate of 16 times or more in the range of 0 to 200 ml / 100 g. When such a specific polymer powder is used as a thickener, an acrylic SMC or BMC excellent in handleability and productivity is obtained, and a molded article having a good appearance tends to be obtained.

This is because the bulk density of the polymer powder is 0.1 g /
When the amount is at least ml, the polymer powder is less likely to scatter, the yield at the time of its production is good, the powderiness when adding and mixing the polymer powder to the acrylic premix is reduced, and the workability is good. In addition, when the amount is 0.7 g / ml or less, it is possible to obtain a sufficient thickening effect by using a small amount of the polymer powder, and the thickening can be completed in a short time. Is improved,
This is because it is advantageous in terms of cost. Preferably, 0.
It is in the range of 15 to 0.65 g / ml, and more preferably in the range of 0.2 to 0.6 g / ml.

Further, by setting the oil absorption amount of the polymer powder to linseed oil to be 60 ml / 100 g or more, it becomes possible to obtain a sufficient thickening effect even if a small amount of the polymer powder is used, and the thickening can be carried out in a short time. This is because the productivity is improved and the cost is also improved.
When the amount is 100 g or less, the dispersibility of the polymer powder in the acrylic premix becomes good,
This is because the kneading property at the time of producing the acrylic SMC or BMC is improved. Preferably 70-180 ml /
It is in the range of 100 g, more preferably 80 to 14
It is in the range of 0 ml / 100 g.

Further, by making the degree of swelling of the polymer powder with respect to methyl methacrylate 16 times or more, the effect of thickening the acrylic premix becomes sufficient. It is more preferably 20 times or more.

Since the polymer powder is a non-crosslinked polymer powder, a sufficient thickening effect can be obtained in a short time, and an acrylic SMC or BMC containing this polymer powder can be used for the production of granite-like artificial marble. This is because when used, the sharpness of the stone pattern tends to improve and the unevenness of the stone pattern tends to disappear. It is considered that such a tendency is due to the fact that, after the non-crosslinked polymer powder swells in the acrylic premix, a part or all of the powder dissolves immediately at room temperature.

In the present invention, the non-crosslinked polymer powder is a polymer powder in which at least the surface layer portion is composed of the non-crosslinked polymer.

The weight average molecular weight of the polymer powder used in the present invention is not particularly limited, but it is 100,000-2.
It is preferably in the range of, 000,000.

Since the weight average molecular weight is within this range, a sufficient thickening effect can be obtained in a short time, and acrylic SMC or BMC containing this polymer powder is used for the production of 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. The range is more preferably 300,000 to 2,000,000, and particularly preferably the range is 400,000 to 1,000,000.

The amount of the polymer powder used in the present invention is not particularly limited, but 0.1 to 100 polymer powder is added to 100 parts by weight of the acrylic resin composition of the present invention.
It is preferably in the range of parts by weight. 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, the dispersibility of the polymer powder becomes good, and in terms of cost. This is because it tends to be advantageous. The more preferable amount of the polymer powder used is 1 to
It is in the range of 80 parts by weight.

The specific surface area of the polymer powder used in the present invention is not particularly limited, but is 1 to 100.
It is preferably in the range of m ² / g.

This is because the specific surface area of the polymer powder is 1 m ² /
When the amount is at least g, a sufficient thickening effect can be obtained with the use of a small amount of the polymer powder, and the viscosity can be increased in a short time, so that the productivity is improved, and further the polymer powder is contained. when using the acrylic SMC or BMC in granite finished artificial marble manufacture, the better the sharpness of pebbled pattern, tend to pattern non-uniformity of the pebble is lost, also, 100 m ²
This is because when the content is not more than / g, the dispersibility of the polymer powder in the acrylic premix becomes good, and thus the kneading property at the time of producing the acrylic SMC or BMC tends to become good. More preferably 3-100
m ² / g, more preferably 5 to 100 m ²
/ G range.

The average particle size of the polymer powder 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 powder dusting tends to be reduced and the handling property of the polymer powder tends to be good, and when the average particle diameter is 250 μm or less, the molding material obtained is This is because the appearance, especially gloss and surface smoothness tend to be good. The range is more preferably 5 to 150 μm, further preferably 10 to 70 μm.

The polymer powder used in the present invention is preferably a secondary aggregate in which primary particles are aggregated. This is because when the polymer powder has the shape of a secondary agglomerate, the absorption rate of the component (a) of the present invention is high and the viscosity increase tends to be extremely good.

Further, in this case, the average particle diameter of the primary particles of the polymer powder is preferably in the range of 0.03 to 1 μm. This means that the average particle size of the primary particles is 0.
When the average particle size is 03 μm or more, the yield during the production of the polymer powder, which is a secondary aggregate, tends to be good, and 1
When the particle size is less than or equal to μm, a sufficient thickening effect can be obtained with the use of a small amount of the polymer powder, and the viscosity can be increased in a short time, so that the productivity is improved. When acrylic SMC or BMC is used for the production of granite-like artificial marble, the sharpness of the stone pattern is improved,
This is because the unevenness in the pattern of stones tends to disappear. More preferably, it is in the range of 0.07 to 0.7 μm.

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 Taking this into consideration, an acrylic polymer is preferable.

As the constituent components of the polymer powder, for example,
Alkyl (meth) having an alkyl group having 1 to 20 carbon atoms
Acrylate, cyclohexyl (meth) acrylate,
Isobornyl (meth) acrylate, glycidyl (meth) acrylate, hydroxyalkyl (meth) acrylate, benzyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, trifluoroethyl (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, taking into consideration their affinity with the monomer components constituting the acrylic premix. And (meth) acrylic monomers are preferred.

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 preferably a non-crosslinked polymer.

The constituents of the core phase and shell phase of the polymer powder include, for example, alkyl (meth) acrylate having an alkyl group having 1 to 20 carbon atoms, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, glycidyl ( (Meth) acrylate, hydroxyalkyl (meth) acrylate, benzyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, trifluoroethyl (meth) acrylate, (meth) acrylic acid, (meth) acrylic acid metal salt, fumaric acid, Examples thereof include fumaric acid ester, maleic acid, maleic acid ester, aromatic vinyl, vinyl acetate, (meth) acrylic acid amide, (meth) acrylonitrile, vinyl chloride and maleic anhydride. These may be polymerized alone or may be copolymerized in combination of two or more as necessary, but from the viewpoint of increasing the affinity with the monomer components constituting the acrylic premix. The shell phase preferably uses methyl methacrylate as a main component.

When the core phase 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 , 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 can be used as a constituent component, and these can be used alone or in combination of two or more kinds.

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.

In the acrylic premix of the present invention, if necessary, benzoyl peroxide, lauroyl peroxide, t-butyl hydroperoxide, cyclohexanone peroxide, methyl ethyl ketone peroxide, t-butyl peroxyoctoate. , T-butylperoxybenzoate, dicumyl peroxide, 1,1-bis (t-butylperoxy)
Organic peroxides such as 3,3,5-trimethylcyclohexane and azobisisobutyronitrile, curing agents such as azo compounds, reinforcing materials such as glass fibers and carbon fibers, coloring agents, low-shrinking agents, curing agents, internal Various additives such as a release agent can be added.

The method of mixing the constituents 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 highly viscous substance. For example, a kneader, mixer, roll, extruder or the like can be used.

When an artificial marble is produced by heating the acrylic premix of the present invention into acrylic SMC or BMC and then heat-pressurizing it, a known method such as compression molding, injection molding or extrusion molding is used. It can be manufactured.

In this case, the heating temperature is not particularly limited, but is preferably in the range of 100 to 150 ° C. this is,
By setting the heating temperature to 100 ° C. or higher, the curing time can be shortened and the productivity tends to increase,
This is because when the temperature is 150 ° C. or lower, the linear shrinkage of the obtained molded product tends to be low. More preferably 105 to 145 ° C, particularly preferably 110 to 140.
It is in the range of ° C. Further, the upper mold and the lower mold may be heated with a temperature difference within the above temperature range.

Pressurized pressure is 10 to 200 kg / cm
A range of ² is preferred. This applies a pressure of 10 kg / c
By the m ² or more, the acrylic SMC or B
The filling property of MC into the mold tends to be good, and
This is because when the content is 0 kg / cm ² or less, a good molded appearance without whitening tends to be obtained. More preferably, it is in the range of ^{20 to} 150 kg / cm ² .

The molding time may be appropriately selected depending on the thickness of the molded product.

The artificial marble obtained by heating and curing the acrylic BMC or SMC of the present invention is
Excellent molding appearance.

[0064]

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: Average particle diameter: measured using a laser diffraction / scattering type particle size distribution measuring device (LA-910, manufactured by Horiba Ltd.). Bulk density: Measured based on JIS R 6126-1970. Oil absorption: Measured based on JIS K 5101-1991, and the end point was just before the putty-like mass suddenly became soft with the last drop of linseed oil. Specific surface area: Measured by a nitrogen adsorption method using a surface area meter SA-6201 (manufactured by Horiba Ltd.). Weight average molecular weight: a value measured by the GPC method (in terms of polystyrene). Swelling degree: Polymer powder is put into a graduated cylinder of 100 ml, tapped several times to fill 5 ml, and then methyl methacrylate cooled to 10 ° C. or below is put so that the total amount becomes 100 ml, and the whole becomes uniform. So that it stirs quickly. 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).

(1) Production Example of Polymer Powder (P-1) 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 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 to obtain an emulsion having a polymer primary particle diameter of 0.08 μm.

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.
50 degreeC / 90 degreeC spray drying process was carried out, and the non-crosslinked polymer powder (P-1) whose average particle diameter of a secondary aggregate particle is 30 micrometers was obtained. The bulk density of the obtained (P-1) was 0.40 g / ml, and the oil absorption amount for linseed oil was 100 ml / 100.
and the degree of swelling with respect to methyl methacrylate is 20.
It was more than double, the specific surface area was 51 m ² / g, and the weight average molecular weight was 600,000.

(2) Production Example of Polymer Powder (P-2) 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, 149.85 parts of methyl methacrylate, 1,3-
A mixture of 0.15 parts of butylene glycol dimethacrylate and 5 parts of sodium dialkyl sulfosuccinate (trade name Perex OT-P, manufactured by Kao Corporation) was added to 1.5 parts.
After dropping over a period of time and holding for 1 hour, 350 parts of methyl methacrylate was dropped over a period of 3.5 hours,
Hold for 1 hour, further raise to 80 ° C., hold for 1 hour to complete emulsion polymerization, and the primary particle diameter of the polymer is 0.10 μm.
An m 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 polymer powder having a core / shell structure in which the secondary aggregate particles have an average particle diameter of 20 μm, the core phase is a crosslinked polymer, and the shell phase is a non-crosslinked polymer after spray drying treatment at 50 ° C./90° C. ( P-2) was obtained. The bulk density of the obtained (P-2) was 0.38 g / ml, and the oil absorption amount for linseed oil was
100 ml / 100 g, the degree of swelling with respect to methyl methacrylate is 20 times or more, and the specific surface area is 51 m ^2.
/ G, and the weight average molecular weight of the shell phase was 600,000.

(3) Production Example of Polymer Powder (P-3) The charged amount of potassium persulfate was 0.25 part, the monomer to be dropped was 497.5 parts of methyl methacrylate, and 1,3-butylene glycol dimethacrylate. Emulsion polymerization was carried out in the same manner as in the production example of the polymer powder (P-1) except that the mixture was 2.5 parts and 5 parts of sodium dialkylsulfosuccinate, and the primary particle diameter of the polymer was 0.18 μm. An emulsion was obtained. The obtained emulsion was spray-dried in the same manner as in Production Example (1) to obtain a crosslinked polymer powder (P-3) having a secondary aggregate particle average particle size of 18 μm. The bulk density of the obtained (P-3) is 0.38 g / ml.
And the oil absorption for linseed oil is 95 ml / 100
and the degree of swelling with respect to methyl methacrylate is 20.
It was more than double and the specific surface area was 24 m ² / g.

(4) Polymethylmethacrylate (B-
Production example 1) In a reactor equipped with a cooling pipe, a thermometer, a stirrer, and a nitrogen introducing pipe, 800 parts of pure water, 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, and then further 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 was filtered, washed, and then dried with a hot air dryer at 50 ° C. to obtain polymethyl methacrylate (B-1) having an average primary particle diameter of 93 μm. The bulk density of the obtained (B-1) was 0.70 g / ml, and the oil absorption amount for linseed oil was
45 ml / 100 g, swelling degree to methyl methacrylate is 1.2, specific surface area is 0.07 m ² /
and the weight average molecular weight was 40,000.

(5) Production Example of Resin Particles Containing Inorganic Filler Mixture 100 consisting of 69% methyl methacrylate, 2% ethylene glycol dimethacrylate, and 29% polymethyl methacrylate (B-1) obtained in the above Production Example (4).
Part, 2.0 parts of t-butyl peroxybenzoate (manufactured by NOF CORPORATION, trade name Perbutyl Z) as a curing agent,
After adding 0.5 parts of zinc stearate and 0.25 parts of white inorganic pigment or black inorganic pigment as an internal mold release agent, aluminum hydroxide (manufactured by Showa Denko KK,
200 parts of Hydilite H-310 (trade name) was added, and the polymer powder (P-1) 30 obtained in the above Production Example (1) was further added.
Part, and knead with a kneader for 10 minutes to prepare acrylic B
I got MC. Next, a 200 mm square flat mold is filled with acrylic BMC and the mold temperature is 130 ° C. and the pressure is 100.
The acrylic artificial marble having a thickness of 10 mm was obtained by heating and curing under a condition of kg / cm ² for 10 minutes. The obtained acrylic artificial marble was crushed with a crusher to obtain white or black inorganic filler-containing resin particles having an average particle diameter of 350 μm.

[Example 1] Tetrahydrofurfuryl methacrylate (manufactured by Mitsubishi Rayon Co., Ltd., trade name Acryester THF) 25%, methyl methacrylate (manufactured by Mitsubishi Rayon Co., Ltd., trade name Acryester M) 23%, neopentyl Glycol dimethacrylate (Shin-Nakamura Chemical Co., Ltd., trade name NK ester NPG) 25%, ethylene glycol dimethacrylate (Mitsubishi Rayon Co., Ltd.)
Manufactured by Acryester ED) 2% and polymethyl methacrylate (B-1) 25% obtained in the above Production Example (1) to 100 parts of an acrylic resin composition containing the component (a) and the component (b). , 1,1-bis (t-butylperoxy) 3,3,5-trimethylcyclohexane as a curing agent (trade name Perhexa 3M, manufactured by NOF CORPORATION) 2.0
Parts, 0.5 parts of zinc stearate as an internal mold release agent, and then aluminum hydroxide (manufactured by Showa Denko KK, trade name Heidilite H-310) 195 as an inorganic filler.
25 parts by weight of the polymer powder (P-1) obtained in the above Production Example (1) was added and kneaded with a kneader for 10 minutes to obtain an acrylic BMC. Obtained acrylic BMC
Has no stickiness immediately after kneading, and does not have an odor.
The handleability was extremely good.

Next, the obtained acrylic BMC was filled in a molding die, and the upper die temperature was 140 ° C. and the lower die temperature was 1.
The mixture was heated and pressed for 10 minutes under the conditions of 25 ° C. and a pressure of 100 kg / cm ² to obtain a 200 mm square acrylic artificial marble molded product having a thickness of 10 mm.

Even when this acrylic artificial marble was molded, no odor was generated and the handleability was extremely good.

The surface of the obtained molded product had no gloss unevenness, the gloss was extremely high, and the appearance was very good.

Example 2 An acrylic BM was prepared in the same manner as in Example 1 except that tetrahydrofurfuryl methacrylate was 19% and methyl methacrylate was 29%.
I got C. The results of thickening are shown in Table 1.

Next, an acrylic artificial marble was obtained in the same manner as in Example 1. Table 1 shows the odor during handling and the appearance of the obtained molded product.

Example 3 Acrylic BM was prepared in the same manner as in Example 1 except that tetrahydrofurfuryl methacrylate was 15% and methyl methacrylate was 33%.
I got C. The results of thickening are shown in Table 1.

Next, an acrylic artificial marble was obtained in the same manner as in Example 1. Table 1 shows the odor during handling and the appearance of the obtained molded product.

Example 4 Acrylic BMC was prepared in the same manner as in Example 1 except that tetrahydrofurfuryl methacrylate was 9% and methyl methacrylate was 39%.
Got The results of thickening are shown in Table 1.

Next, an acrylic artificial marble was obtained in the same manner as in Example 1. Table 1 shows the odor during handling and the appearance of the obtained molded product.

Example 5 As polymer powder (P-2)
In the same manner as in Example 1, except that
I got MC. The results of thickening are shown in Table 1.

Next, an acrylic artificial marble was obtained in the same manner as in Example 1. Table 1 shows the odor during handling and the appearance of the obtained molded product.

Example 6 15% of neopentyl glycol dimethacrylate, polymethyl methacrylate (B
Acrylic BMC was obtained by the same method as in Example 1 except that -1) was 35% and the polymer powder was (P-3). The results of thickening are shown in Table 1.

Next, an acrylic artificial marble was obtained in the same manner as in Example 1. Table 1 shows the odor during handling and the appearance of the obtained molded product.

[Example 7] Instead of tetrahydrofurfuryl methacrylate, tetrahydrofurfuryl acrylate (Kyoeisha Chemical Co., Ltd., light acrylate THF) was used.
An acrylic BMC was obtained in the same manner as in Example 1 except that -A) was used. The results of thickening are shown in Table 1.

Next, an acrylic artificial marble was obtained in the same manner as in Example 1. Table 1 shows the odor during handling and the appearance of the obtained molded product.

[Example 8] Tetrahydrofurfuryl methacrylate 24%, methyl methacrylate 24%, neopentyl glycol dimethacrylate 25%, ethylene glycol dimethacrylate 2% and the above production example (1).
1,1-bis (t-butylperoxy) as a curing agent was added to 100 parts of the acrylic resin composition containing 25% of the polymethyl methacrylate (B-1) obtained in (a) and (b). ) 2.0 parts of 3,3,5-trimethylcyclohexane, 0.5 parts of zinc stearate as an internal release agent
Aluminum hydroxide (manufactured by Showa Denko KK, trade name Heidilite H-31) as an inorganic filler
0) 170 parts and 70 parts in total of the black and white inorganic filler-containing resin particles obtained in the above Production Example (5) were added, and further the polymer powder (P-1) obtained in the above Production Example (1) Twenty-five parts were added and kneaded with a kneader for 10 minutes. The obtained stone-tone acrylic BMC was not sticky even immediately after kneading, did not have an odor, and was extremely easy to handle.

Then, a granite-like acrylic artificial marble molding was obtained in the same manner as in Example 1. Odor when handling,
Table 1 shows the appearance of the obtained molded product.

[Comparative Example 1] The acrylic resin composition was composed of 48% methyl methacrylate, 25% neopentyl glycol dimethacrylate, 2% ethylene glycol dimethacrylate, and the polymethylmethacrylate (B- 1) An acrylic BMC was obtained in the same manner as in Example 1 except that the mixture was 25%. The obtained acrylic BMC had an unpleasant odor peculiar to the monomer. The results of thickening are shown in Table 1.

Next, an acrylic artificial marble was obtained in the same manner as in Example 1. The obtained molded product had uneven gloss and had a poor appearance. In addition, there was an unpleasant odor when obtaining the molded product.

Comparative Example 2 Example 1 except that styrene was used instead of tetrahydrofurfuryl methacrylate.
An acrylic BMC was obtained in the same manner as in. The results of thickening are shown in Table 1.

Next, an acrylic artificial marble was obtained in the same manner as in Example 1. The obtained molded product had extremely uneven gloss and low gloss, and had a very poor appearance. Also, B
There was an unpleasant odor peculiar to the monomer when handling MC or when obtaining a molded product.

[0095]

[Table 1]

THFMA: Tetrahydrofurfuryl methacrylate THFA: Tetrahydrofurfuryl acrylate MMA: Methyl methacrylate NPGDMA: Neopentyl glycol dimethacrylate EDMA: Ethylene glycol dimethacrylate ST: Thickening of styrene / premix A: Thickening immediately after kneading A premix with no stickiness and good handleability was obtained. B: After kneading, it took 24 hours or more to age at room temperature and increase the viscosity to the required viscosity.

-Non-uniform gloss of molded products ⊚: There is no gloss unevenness and the gloss is extremely high. ○ +: There is no gloss unevenness and the gloss is considerably high. ◯: High gloss with no uneven gloss. Δ: There is uneven gloss and the gloss is low. X: The gloss unevenness is severe and the gloss is extremely low.

Odor ⊚: No odor was produced during manufacture and handling of BMC or during molding of BMC. ◯: Almost no odor was produced during production and handling of BMC or during molding of BMC. X: There was an unpleasant odor peculiar to the monomer during the production and handling of BMC or during the molding of BMC.

[0099]

As is apparent from the above examples, by using (meth) acrylate having an ester group having a specific structure as the acrylic resin composition, a molded appearance without gloss unevenness can be obtained, It becomes possible to obtain an acrylic resin composition having excellent processability, an acrylic premix useful as a raw material for an acrylic artificial marble, and further to include a polymer powder as a thickener in the acrylic premix. As a result, it becomes possible to obtain an acrylic SMC or BMC that is particularly useful as a raw material for an acrylic artificial marble that has little odor and is excellent in handleability during high-temperature molding processing, and further obtain an acrylic obtained using this. Artificial marble is highly productive, has a good appearance, and is very useful industrially.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-6-219800 (JP, A) JP-A-58-206621 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C08F 265/06 C08F 2/44

Claims (6)

(57) [Claims] 1. Tetrahydrofurfuryl (meth) acrylate or a monomer mixture (a) containing the same, and
An acrylic resin composition containing 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. An acrylic SM containing the acrylic premix according to claim 2 and a thickener.
C or BMC. 5. The acrylic SMC or BMC according to claim 4, wherein the thickener is a polymer powder. 6. The acrylic SMC or B according to claim 4.
A method for producing an acrylic artificial marble, which comprises heat-pressurizing and hardening MC in the range of 100 to 150 ° C.