JP3433890B2 - Method for producing acrylic resin composition, acrylic premix, acrylic SMC or BMC, and acrylic artificial marble - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an acrylic resin composition excellent in moldability, an acrylic premix useful as a raw material for an acrylic artificial marble, an acrylic premix which is suitable for high temperature molding and has excellent moldability. Acrylic SMC or BMC which is particularly useful as a raw material for a synthetic artificial marble, and
The present invention relates to a method for producing an acrylic artificial marble with 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, studies have been conventionally made to produce an acrylic artificial marble by heat-pressing SMC or BMC obtained by thickening a resin syrup with a thickener. .

[0004] For example, in Japanese Patent Laid-Open No. 32720/1993, acrylic resin for artificial marble, which has good handleability and moldability, is obtained by blending an acrylic syrup with a crosslinked resin powder having a specific degree of swelling obtained by suspension polymerization. The system SMC or BMC is disclosed. In addition, JP-A-6-29888
Japanese Patent Publication No. 3 discloses an acrylic SMC or BMC for artificial marble, which is an acrylic syrup blended with a thermoplastic acrylic resin powder that is sparingly soluble in the acrylic syrup and has excellent low shrinkage during heat curing. Has been done. Further, in JP-A-6-313019, a resin powder obtained by spray-drying a cross-linked polymer obtained by emulsion polymerization is blended with an acrylic syrup to prevent cracking during molding and to improve the appearance of a molded product. Also disclosed is an acrylic SMC or BMC for artificial marble, which is characterized by improving the stability of thickening.

[0005]

However, the acrylic SMC or BMC as described in these prior arts is used.
If an attempt is made to produce an artificial marble by using, the sink mark is likely to occur on the surface of the molded product due to shrinkage during polymerization. Further, when an insert screw is inserted into a molded product or when the thickness of the molded product changes, a defect such as sink mark or whitening is likely to occur on the front side of the insert screw or on the wall thickness changing portion. Such a tendency is particularly remarkable when the curing temperature is increased in order to manufacture a molded product in a short time.

Further, the acrylic SMCs or BMCs described in these prior arts require aging for a long time (24 hours or more) in order to increase the viscosity, and have a problem of low productivity.

An object of the present invention is to provide an acrylic resin composition which is free from sink marks and whitening on the front side of the insert screw and on the wall thickness varying portion and which is excellent in moldability and is useful as a raw material for acrylic artificial marble. -Based premix, acrylic SMC or BMC that is particularly useful as a raw material for an acrylic artificial marble that is suitable for high-temperature molding and has excellent moldability, and a method for producing an acrylic artificial marble that is highly productive and has a good appearance. Is to provide.

[0008]

Means for Solving the Problems As a result of studying the above-mentioned problems, the present inventors have found that the acrylic resin composition contains an organic peroxide having a specific structure as a curing agent, whereby We have found an acrylic resin composition with excellent molding processability that does not cause sink marks or whitening in areas where the wall thickness changes, and an acrylic premix that is useful as a raw material for acrylic artificial marble. By including the polymer powder in the premix, it was found that the acrylic SMC or BMC suitable for high-temperature molding and excellent in moldability and particularly useful as a raw material for an acrylic artificial marble has high productivity.
The present invention has been completed by finding a method for producing an acrylic artificial marble having an excellent appearance.

That is, the present invention is represented by methyl methacrylate or (meth) acrylic monomer mixture (a), polymethylmethacrylate or acrylic copolymer (b), and the following general formula (I). The present invention relates to an acrylic resin composition containing a curing agent (c), and an acrylic premix containing the acrylic resin composition and an inorganic filler. And an acrylic SM containing the acrylic premix and a polymer powder
C or BMC ; using the acrylic premix of the present invention
To produce molded products with varying wall thickness, or
Acrylic artificial marble characterized by sart molding
1. Acrylic SMC or BMC of the present invention
A method for producing a (meth) acrylic artificial marble, which comprises heating and pressurizing within a range of 05 to 150 ° C . ; and
And heat and pressure hardness within the range of 105 to 150 ° C.
To produce molded products with varying wall thickness, or
Acrylic artificial physics characterized by insert molding
The present invention relates to a stone manufacturing method .

[0010]

[Chemical 2]

(In the formula, R ₁ and R ₃ represent an alkyl group having 1 to 6 carbon atoms, and R ₂ represents an alkylene group having 1 to 6 carbon atoms.)

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The methyl methacrylate or (meth) acrylic monomer mixture (a) constituting the acrylic resin composition of the present invention preferably contains methyl methacrylate in an amount of 50 to 100% by weight. The unsaturated monomer or unsaturated monomer mixture contained. The content of the component (a) is not particularly limited, but workability when the acrylic resin composition of the present invention is used as an acrylic premix, and the acrylic premix used as the acrylic artificial marble. Considering physical properties such as mechanical strength when used as a raw material for
Is preferred. This is because the content of the component (a) is 30
When the content is at least wt%, the acrylic resin composition has a low viscosity and its handleability is good, and
This is because when the content of the component (a) is 90% by weight or less, the shrinkage factor during curing tends to be low.
More preferably 40 to 85% by weight, still more preferably 5
It is in the range of 0 to 80% by weight.

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

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

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

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

The content of the component (b) is not particularly limited, but workability when the acrylic resin composition of the present invention is used as an acrylic premix, and the acrylic premix is used as an acrylic premix. Considering physical properties such as mechanical strength when used as a raw material for the artificial artificial marble, the range of 10 to 70% by weight is preferable. The range is more preferably 15 to 60% by weight, and further 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, 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 300,000. More preferably, it is in the range of 25,000 to 250,000.

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

The 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 curing agent (c) represented by the following general formula (I), which constitutes the acrylic resin composition of the present invention, suppresses the occurrence of sink marks and whitening on the front side of the insert screw and the wall thickness varying portion. Is used for.

[0022]

[Chemical 3]

(In the formula, R ₁ and R ₃ represent an alkyl group having 1 to 6 carbon atoms, and R ₂ represents an alkylene group having 1 to 6 carbon atoms.) Examples of R ₁ and R ₃ include methyl. Group, ethyl group, n
-Propyl group, i-propyl group, n-butyl group, i-butyl group, sec-butyl group, t-butyl group, n-pentyl group, n-hexyl group and the like can be mentioned, and among them, as R _1. Is preferably a methyl group, and R ₃ is preferably an n-butyl group. Examples of R ₂ include methylene group, ethylene group, n-propylene group, i-propylene group, n-butylene group, i-butylene group, sec-butylene group, t-butylene group, n-pentylene group, Examples thereof include an n-hexylene group, and among them, an ethylene group is preferable.

Specific examples of the curing agent (c) of the present invention include:
In the above general formula (I), R ₁ is a methyl group having 1 carbon atom, R ₂ is an ethylene group having 2 carbon atoms, and R ₃ is a butyl group having 4 carbon atoms. (T-butyl peroxy) valerate (trade name Perhexa V manufactured by NOF CORPORATION, trade name Trigonox 17/40 manufactured by Kayaku Akzo Co., Ltd.) can be used. These are
Alternatively, two or more kinds can be used in combination.

Although the content of the component (c) constituting the acrylic resin composition of the present invention is not particularly limited,
With respect to 100 parts by weight of the total of the components (a) and (b),
The range of 0.01 to 10 parts by weight is preferable. this is,
By setting the content of the component (c) to 0.01 parts by weight or more, the curability of the acrylic resin composition of the present invention becomes sufficient, and by setting it to 10 parts by weight or less, the front side and the wall thickness of the insert screw This is because the molded appearance tends to be obtained without the occurrence of sink marks and whitening at the changed portion. The range is more preferably 0.1 to 5 parts by weight.

As the curing agent used in the acrylic resin composition of the present invention, an organic peroxide or an azo compound other than the component (c) may be used in combination, if necessary.

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 300 parts by weight with respect to 100 parts by weight of the acrylic resin composition. This is because when the amount of the inorganic filler used is 50 parts by weight or more, the obtained molded product has good texture and heat resistance, and when it is 300 parts by weight or less, the insert of the molded product obtained is This is because the occurrence of sink marks and whitening tends to be suppressed on the front side of the screw and the wall thickness varying portion. More preferably, it is in the range of 100 to 250 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 mixing and molding the acrylic premix of the present invention with inorganic filler-containing resin particles, a granite-like artificial marble having a stone pattern can be obtained.

The blending amount of the inorganic filler-containing resin particles is not particularly limited, but 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. 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 may be heat-cured or redox-cured by a casting method as it is, or by adding a thickening agent to the acrylic SMC or B.
Although it may be heated and pressure-cured after being made into MC, it is preferable from the viewpoint of productivity that it is made into acrylic SMC or BMC and then heated and pressure-cured.

When the acrylic premix of the present invention is used as an acrylic SMC or BMC, the thickener is not particularly limited and, for example, magnesium oxide powder or polymer powder can be used. It is preferable to use a polymer powder 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 gives a bulk density of the polymer powder of 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.

In addition, the oil absorption amount of the polymer powder with respect to the linseed oil is set to 60 ml / 100 g or more, whereby a sufficient thickening effect can be obtained by using a small amount of the polymer powder, and the thickening effect is further increased. This is because the productivity can be improved and the cost can be improved because it can be done in a short time.
This is because when the amount is 0 ml / 100 g or less, the dispersibility of the polymer powder in the acrylic premix becomes good, and the kneading property at the time of producing the acrylic SMC or BMC becomes good. Preferably 70-18
The range is 0 ml / 100 g, and more preferably 8
It is in the range of 0 to 140 ml / 100 g.

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

Furthermore, since the polymer powder is a non-crosslinked polymer powder, a sufficient thickening effect can be obtained in a short time, and the acrylic SMC or B containing the polymer powder can be obtained.
This is because when the MC is used for producing a granite-like artificial marble, the sharpness of the stone pattern tends to be improved, and the unevenness of the stone pattern tends to be eliminated. 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 is 100,000 to 2
It is preferably in the range of, 000,000.

This is because when the weight average molecular weight is 100,000 or more, a sufficient thickening effect is obtained in a short time, and acrylic SMC or BMC containing this polymer powder is used for the production of granite-like artificial marble. When this is done, the sharpness of the stone pattern tends to improve, and the unevenness of the stone pattern tends to disappear. Also, by setting it to 2 million or less, the surface side of the insert screw of the obtained molded product and the portion where the wall thickness changes Sink in
This is because the occurrence of whitening tends to be suppressed. 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 it is the component (a) and the component (b) of the present invention.
0.1 parts by weight of polymer powder to 100 parts by weight of the total of the components
It is preferably in the range of 100 to 100 parts by weight. this is,
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 it is 100 parts by weight or less, the dispersibility of the polymer powder becomes good and the cost becomes advantageous. This is because there is a tendency. The more preferable amount of the polymer powder used is in the range of 1 to 80 parts by weight.

The specific surface area of the polymer powder used in the present invention is not particularly limited, but it is from 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) or the component (b) of the present invention is high, and the viscosity increase tends to be extremely good. .

In this case, the average particle size of the primary particles of the polymer powder is preferably 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,
Glycidyl (meth) acrylate, hydroxyalkyl (meth) acrylate, (meth) acrylic acid, (meth)
Acrylic acid metal salts, fumaric acid, fumaric acid ester, maleic acid, maleic acid ester, aromatic vinyl, vinyl acetate, (meth) acrylic acid amide, (meth) acrylonitrile, vinyl chloride, maleic anhydride and the like can be mentioned. These may be polymerized alone or may be copolymerized by using two or more kinds in combination, if necessary, 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 needs to be a non-crosslinked polymer.

The constituents of the core phase and shell phase of the polymer powder include, for example, alkyl (meth) acrylates having an alkyl group having 1 to 20 carbon atoms, cyclohexyl (meth) acrylate, glycidyl (meth) acrylate, hydroxyalkyl. (Meth) acrylate, (meth) acrylic acid, (meth) acrylic acid metal salt, fumaric acid, fumaric acid ester, maleic acid, maleic acid ester, aromatic vinyl, vinyl acetate, (meth) acrylic acid amide, (meth) Examples thereof include acrylonitrile, vinyl chloride, maleic anhydride and the like. 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 an 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.

If necessary, the acrylic premix of the present invention may contain a reinforcing material such as glass fiber or carbon fiber,
Various additives such as a colorant, a low-shrinking agent and an internal 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.

The acrylic premix of the present invention may be heat-cured or redox-cured as it is by a casting method, or a thickener may be added to the acrylic SMC or B.
You may heat-press-harden after setting it as MC.

When an artificial marble is produced by heating the acrylic premix of the present invention into acrylic SMC or BMC and then heating and pressurizing it, a known method such as a compression molding method, an injection molding method or an extrusion molding method 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,
When the heating temperature is 100 ° C or higher, the curability tends to be sufficient, and when the heating temperature is 150 ° C or lower, sink marks and whitening occur on the front side of the insert screw of the molded product and the wall thickness change part. This is because there is a tendency to be suppressed. The range is more preferably 105 to 140 ° C, and particularly preferably 110 to 130 ° C. In the case of heat-pressurizing and curing, the upper die and the lower die 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 .

[0066]

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 particle size distribution analyzer (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: measured value by GPC method (in terms of polystyrene) Swelling degree: Polymer powder was put into a graduated cylinder of 100 ml, tapped several times to fill 5 ml, and then the total amount of methyl methacrylate cooled to 10 ° C. or lower was Add to 100ml and stir quickly to make the whole uniform. Then, the graduated cylinder was kept in a constant temperature bath at 25 ° C. for 1 hour, and the volume of the polymer powder layer after swelling was determined and shown by the ratio to the volume before swelling (5 ml).

(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 polyoxyethylene nonylphenyl ether. (Kao Corporation, trade name Emulgen 930) 5 parts and potassium persulfate 1.5 parts were charged and heated to 70 ° C. with stirring under a nitrogen atmosphere. To this, 500 parts of methyl methacrylate and sodium dialkylsulfosuccinate (Kao Corporation, trade name Perex OT
-P) A mixture of 10 parts was added dropwise over 3 hours, then maintained for 1 hour, further heated to 80 ° C and maintained for 1 hour to complete the emulsion polymerization, and the polymer had a primary particle diameter of 0.1.
A 0 μm emulsion was obtained. The obtained emulsion was spray-dried at an inlet temperature / outlet temperature = 150 ° C./90° C. using an L-8 type spray dryer manufactured by Okawara Kakoki Co., Ltd., and the average particle size of the secondary aggregate particles was 20 μm. A crosslinked polymer powder (P-1) was obtained. The physical properties of the obtained (P-1) are shown in Table 1.

(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, 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 spray-dried using an L-8 type spray dryer manufactured by Okawara Kakoki Co., Ltd., and the average particle size of the secondary aggregate particles was 30 μm.
m non-crosslinked polymer powder (P-2) was obtained. The physical properties of the obtained non-crosslinked polymer powder (P-2) are shown in Table 1.

(3) Production Example of Polymer Powder (P-3) A reactor equipped with a cooling pipe, a thermometer, a stirrer, a dropping device, and a nitrogen introducing pipe was charged with 625 parts of pure water and sodium alkyldiphenyl ether disulphonate. (Kao Corporation, trade name Perex SS-H) 3 parts and potassium persulfate 0.5 part were charged and heated to 70 ° C. with stirring under a nitrogen atmosphere. To this, a mixture of 500 parts of methyl methacrylate and 5 parts of sodium dialkylsulfosuccinate (Kao Corporation, trade name Perex OT-P) was added dropwise over 3 hours, and then the mixture was kept for 1 hour and then heated to 80 ° C. The emulsion was polymerized by heating for 1 hour to obtain an emulsion having a polymer primary particle diameter of 0.11 μm. The obtained emulsion was spray-dried at an inlet temperature / outlet temperature = 150 ° C./90° C. using an L-8 type spray dryer manufactured by Okawara Kakohki Co., Ltd., and the average particle diameter of the secondary aggregate particles was 50 μm. A crosslinked polymer powder (P-3) was obtained. The physical properties of the obtained (P-3) are shown in Table 1.

(4) Production Example of Polymer Powder (P-4) A reactor equipped with a cooling pipe, a thermometer, a stirrer, a dropping device, and a nitrogen introducing pipe was charged with 925 parts of pure water and sodium alkyldiphenyl ether disulphonate. (Kao Corporation, trade name Perex SS-H) (5 parts) and potassium persulfate (0.25 part) were charged, and the mixture was heated to 70 ° C. with stirring under a nitrogen atmosphere. To this, a mixture of 500 parts of methyl methacrylate and 5 parts of sodium dialkylsulfosuccinate (Kao Corporation, trade name Perex OT-P) was added dropwise over 3 hours, and then the mixture was kept for 1 hour and then heated to 80 ° C. Warm 1
The emulsion polymerization was terminated by holding for a period of time to obtain an emulsion having a polymer primary particle diameter of 0.10 μm. The obtained emulsion was spray-dried at an inlet temperature / outlet temperature = 150 ° C./90° C. using an L-8 type spray dryer manufactured by Okawara Kakoki Co., Ltd., and the average particle size of the secondary aggregate particles was 20 μm. A crosslinked polymer powder (P-4) was obtained. The physical properties of the obtained (P-4) are shown in Table 1.

(5) Production Example of Polymer Powder (P-5) A reactor equipped with a cooling pipe, a thermometer, a stirrer, a dropping device, and a nitrogen introducing pipe was charged with 925 parts of pure water and sodium alkyldiphenyl ether disulphonate. (Kao Corporation, trade name Perex SS-H) 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 heated at the inlet temperature / using an L-8 type spray dryer manufactured by Okawara Kakoki Co., Ltd.
Spray-dried at an outlet temperature of 150 ° C./90° C., the secondary aggregate particles have an average particle size of 20 μm, a core phase is a cross-linked polymer, and a shell phase is a non-cross-linked polymer. A combined powder (P-5) was obtained. Obtained (P-
Table 1 shows the physical property values of 5).

(6) Production Example of Polymer Powder (P-6) The monomer to be dropped is 497.5 parts of methyl methacrylate,
Emulsion polymerization and spray drying were carried out in the same manner as in the production example of the polymer powder (P-4) except that the mixture consisted of 2.5 parts of 1,3-butylene glycol dimethacrylate and 5 parts of sodium dialkylsulfosuccinate. A crosslinked polymer powder (P-6) having an average particle diameter of the secondary aggregate particles of 18 μm.
Got The physical properties of the obtained (P-6) are shown in Table 1.

(7) Production Example of Polymer Powder (P-7) A reactor equipped with a cooling pipe, a thermometer, a stirrer and a nitrogen introducing pipe was charged with 800 parts of pure water and polyvinyl alcohol (saponification degree: 8).
8%, degree of polymerization 1000) 1 part was dissolved, then a monomer solution in which 400 parts of methyl methacrylate and 0.5 part of azobisisobutyronitrile were dissolved was added, and the mixture was stirred at 500 rpm in a nitrogen atmosphere. While heating to 80 ° C. in 1 hour, the mixture was heated as it was for 2 hours. Then, the temperature was raised to 90 ° C. and the mixture was heated for 2 hours, and further heated to 120 ° C. to distill away the residual monomer together with water to obtain a slurry, and the suspension polymerization was completed. The obtained slurry was filtered, washed, and then dried with a hot air dryer at 50 ° C. to obtain a non-crosslinked polymer powder (P-7) having an average primary particle diameter of 30 μm. Obtained (P-
The physical properties of 7) are shown in Table 1.

(8) Production Example of Polymer Powder (P-8) In a reactor equipped with a cooling pipe, a thermometer, a stirrer, and a nitrogen introducing pipe, 800 parts of pure water and polyvinyl alcohol (saponification degree: 8)
After dissolving 1% of 8% and a degree of polymerization of 1000), 398 parts of methyl methacrylate, 2 parts of neopentyl glycol dimethacrylate and 0.4 parts of normal dodecyl mercaptan.
Part, and a monomer solution in which 1.2 parts of azobisisobutyronitrile were dissolved were added, and the mixture was heated to 80 ° C. in 1 hour while stirring at 500 rpm in a nitrogen atmosphere, and heated as it was for 2 hours. Then, the temperature was raised to 90 ° C. and the mixture was heated for 2 hours, and further heated to 120 ° C. to distill away the residual monomer together with water to obtain a slurry, and the suspension polymerization was completed. The obtained slurry is filtered and washed, and then dried with a hot air dryer at 50 ° C. to obtain a crosslinked polymer powder (P- having an average primary particle diameter of 30 μm).
8) was obtained. The physical properties of the obtained (P-8) are shown in Table 1.

(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 introducing pipe was charged with 800 parts of pure water and polyvinyl alcohol (saponification). Degree 8
8%, polymerization degree 1000) 1 part was dissolved, and then a monomer solution in which 400 parts of methyl methacrylate, 2 parts of normaldodecyl mercaptan, and 2 parts of azobisisobutyronitrile were dissolved was added, and under a nitrogen atmosphere, While stirring at 400 rpm, the temperature was raised to 80 ° C. in 1 hour, and heating was continued for 2 hours. After that, the temperature is raised to 90 ° C. and heated for 2 hours, then 1
The residual monomer was distilled off together with water by heating to 20 ° C. to obtain a slurry, and the suspension polymerization was completed. The obtained slurry 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. Table 2 shows the physical property values of the obtained (B-1).

(10) Production Example of Resin Particles (C) Containing Inorganic Filler From 69% methyl methacrylate, 2% ethylene glycol dimethacrylate, and 29% polymethyl methacrylate (B-1) obtained in the above Production Example (9). To 100 parts of the mixture of the components (a) and (b), t-butyl peroxybenzoate (Nippon Oil & Fats Co., Ltd., trade name Perbutyl Z) as a curing agent 2.0 parts Zinc stearate as an internal release agent 0.5 part, white inorganic pigment or black inorganic pigment 0.25
Aluminum hydroxide (manufactured by Showa Denko KK, trade name Heidilite H-31) as an inorganic filler
0) 200 parts was added, and further 30 parts of the polymer powder (P-2) obtained in the above Production Example (2) was added, and the mixture was mixed with a kneader to 10
Kneading for minutes gave an acrylic BMC. Next, the acrylic BMC was filled into a 200 mm square flat mold and was heat-pressed under a mold temperature of 130 ° C. and a pressure of 100 kg / cm ² for 10 minutes to obtain a 10 mm thick acrylic artificial marble. Obtained. The obtained acrylic artificial marble was crushed with a crusher to obtain white or black inorganic filler-containing resin particles (C) having an average particle diameter of 350 μm. The powder characteristics are shown in Table 3.

[0077]

[Table 1]

[0078]

[Table 2]

[0079]

[Table 3]

[Example 1] Methyl methacrylate 48
%, Neopentyl glycol dimethacrylate 25%,
2% of ethylene glycol dimethacrylate and polymethyl methacrylate (B-1) 2 obtained in the above Production Example (9)
In 100 parts of a mixture of (a) component and (b) component consisting of 5%, R ₁ is a methyl group having 1 carbon atom and R ₂ is an ethylene group having 2 carbon atoms in the general formula (I) as a curing agent, R ₃ has 4 carbon atoms
Butyl group n-butyl-4,4-bis (t-butylperoxy) valerate (trade name, Perhexa V, 10-hour half-life temperature = 105 ° C., manufactured by NOF CORPORATION) 2.8
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) 220 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
The sample had no stickiness immediately after kneading and had very good handleability.

Next, the obtained acrylic BMC was filled in a molding die, and the upper die temperature was 125 ° C. and the lower die temperature was 1.
Heat and pressure cure under conditions of 10 ° C. and pressure of 100 kg / cm ² for 10 minutes to change the wall thickness and diameter 9 mm,
A 200 mm square acrylic artificial marble molded product into which an insert screw having a length of 11 mm was inserted was obtained. The shape of the obtained molded product is shown in FIG. The surface of the molded product has extremely high gloss,
The surface smoothness was extremely high in the mirror surface state with no defects. Further, no sink mark or whitening was observed on the front side of the insert screw, and no sink mark or whitening was observed on the front side of the wall thickness change portion, and the appearance was extremely good.

[Examples 2 to 6] As shown in Table 4, 25 parts of (P-2) and (P-5) 2 as polymer powders were used.
5 parts, (P-6) 35 parts, (P-7) 50 parts, (P-
8) An acrylic BMC was obtained in the same manner as in Example 1 except that 40 parts of each was used. The results of thickening are shown in Table 6.
Shown in.

Next, an acrylic artificial marble was obtained in the same manner as in Example 1. Table 6 shows the evaluation results of the appearance of the obtained molded product.

[Comparative Example 1] As shown in Table 4, t-butyl peroxybenzoate (manufactured by NOF CORPORATION, trade name Perbutyl Z, 10-hour half-life temperature =
The same method as in Example 2 except that (104 ° C.) is used,
An acrylic BMC was obtained. The results of thickening are shown in Table 6.

Next, an acrylic artificial marble was obtained in the same manner as in Example 1. Table 6 shows the evaluation results of the appearance of the obtained molded product.

[Comparative Example 2] Methyl methacrylate 55
%, 9% of trimethylolpropane trimethacrylate and 36% of the polymethylmethacrylate (B-1) obtained in the above Production Example (9) in 100 parts of a mixture of the component (a) and the component (b), and t as a curing agent. -Amyl peroxy 2
-Ethyl hexanoate (Kyaku Yakuzo Co., Ltd., trade name Trigonox 121-50, 10-hour half-life temperature = 7)
(0 ° C.) 1.8 parts and 0.5 parts of zinc stearate as an internal mold release agent, and then aluminum hydroxide (manufactured by Showa Denko KK, trade name Hydilite H-) as an inorganic filler.
310) 230 parts, and further 15 parts of the polymer powder (P-6) obtained in the above Production Example (6) were added and kneaded with a kneader for 10 minutes to obtain an acrylic BMC. The results of thickening are shown in Table 6.

Next, an acrylic artificial marble was obtained in the same manner as in Example 1. Table 6 shows the evaluation results of the appearance of the obtained molded product.

[Comparative Example 3] Methyl methacrylate 48
%, Trimethylolpropane trimethacrylate 20%
And 100 parts of a mixture of the component (a) and the component (b) consisting of 32% of the polymethylmethacrylate (B-1) obtained in the above Production Example (9), and t-butylperoxy 2 as a curing agent.
-Ethyl hexanoate (manufactured by NOF CORPORATION, trade name Perbutyl O, 10-hour half-life temperature = 72 ° C) 0.8 part,
After adding 0.5 parts of zinc stearate as an internal mold release agent, 200 parts of aluminum hydroxide (manufactured by Showa Denko KK, trade name Heidilite H-310) was added as an inorganic filler, and the above Production Example was further added. The polymer powder (P) obtained in (7)
-7) 10 parts was added and kneaded with a kneader for 10 minutes to obtain an acrylic BMC. The results of thickening are shown in Table 6.

Next, an acrylic artificial marble was obtained in the same manner as in Example 1. Table 6 shows the evaluation results of the appearance of the obtained molded product.

[Comparative Example 4] Methyl methacrylate 53
%, Neopentyl glycol dimethacrylate 12% and polymethyl methacrylate (B-1) 35% obtained in the above Production Example (9) in 100 parts of a mixture of the component (a) and the component (b). , 2-bis (t-butylperoxy) butane (manufactured by NOF CORPORATION, trade name Perhexa 22, 10-hour half-life temperature = 103 ° C.) 12 parts,
Bis (4-t-butylcyclohexyl) peroxydicarbonate (Nippon Yushi Co., Ltd., trade name Perloyl TC
P, 10 hours half-life temperature = 41 ° C.) 2 parts and dicumyl peroxide (Nippon Yushi Co., Ltd., trade name Park Mill D, 10 hours half-life temperature = 116 ° C.) 1.6 parts, and internal release After adding 0.5 parts of zinc stearate as an agent, 250 parts of aluminum hydroxide (manufactured by Showa Denko KK, trade name Heidilite H-310) was added as an inorganic filler, and the above Production Example (8). The polymer powder (P
-8) 20 parts was added and kneaded with a kneader for 10 minutes to obtain an acrylic BMC. The results of thickening are shown in Table 6.

Next, an acrylic artificial marble was obtained in the same manner as in Example 1. Table 6 shows the evaluation results of the appearance of the obtained molded product.

Example 7 Methyl methacrylate 48
%, Neopentyl glycol dimethacrylate 15%,
2% of ethylene glycol dimethacrylate and polymethyl methacrylate (B-1) 3 obtained in the above Production Example (9)
In 100 parts of a mixture of (a) component and (b) component consisting of 5%, R ₁ is a methyl group having 1 carbon atom and R ₂ is an ethylene group having 2 carbon atoms in the general formula (I) as a curing agent, R ₃ has 4 carbon atoms
Butyl group n-butyl-4,4-bis (t-butylperoxy) valerate (trade name, Perhexa V, 10-hour half-life temperature = 105 ° C., manufactured by NOF CORPORATION) 2.8
Part, and after adding 0.5 part of zinc stearate as an internal release agent, aluminum hydroxide (manufactured by Showa Denko KK, trade name Heidilite H-310) 170 as an inorganic filler
And 70 parts of the black and white inorganic filler-containing resin particles (C) obtained in the above Production Example (10) are added, and further the polymer powder (P-2) obtained in the above Production Example (2) is added. 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 and was extremely easy to handle.

Next, the obtained stone-tone acrylic BM
C was filled in a molding die, and a granite-like acrylic artificial marble molded product was obtained in the same manner as in Example 1. The surface of the molded product had a very high gloss, and the surface smoothness was extremely high in a mirror surface state with no defects. In addition, it had a very clear stone pattern, and there was no unevenness in the stone pattern. further,
No sink mark or whitening was observed on the front side of the insert screw, and no sink mark or whitening was observed on the front side of the thickness change portion, and the appearance was extremely good.

[Examples 8 to 10, Example 12 to Example 14] As shown in Table 5, polymer powders (P-
3) 20 parts, (P-4) 15 parts, (P-5) 25 parts,
(P-6) 35 parts, (P-7) 50 parts, (P-8) 40
In the same manner as in Example 7 except that each part is used,
Grain-tone acrylic BMC was obtained. The results of thickening are shown in Table 7.

Next, a granite-like acrylic artificial marble was obtained in the same manner as in Example 1. Table 7 shows the evaluation results of the appearance of the obtained molded product.

[Example 11] As shown in Table 5, the amount of aluminum hydroxide used was 260 parts, the amount of resin particles containing an inorganic filler was 100 parts, and the amount of polymer powder (P-2) was 20 parts. A stone-grained acrylic BMC was obtained in the same manner as in Example 7 except for the parts. The results of thickening are shown in Table 7.

Next, a granite-like acrylic artificial marble was obtained in the same manner as in Example 1. Table 7 shows the evaluation results of the appearance and linear shrinkage of the obtained molded product.

Example 15 Methyl methacrylate 48
%, Neopentyl glycol dimethacrylate 15%,
2% of ethylene glycol dimethacrylate and polymethyl methacrylate (B-1) 3 obtained in the above Production Example (9)
In 100 parts of a mixture of (a) component and (b) component consisting of 5%, R ₁ is a methyl group having 1 carbon atom and R ₂ is an ethylene group having 2 carbon atoms in the general formula (I) as a curing agent, R ₃ has 4 carbon atoms
Butyl group n-butyl-4,4-bis (t-butylperoxy) valerate (trade name, Perhexa V, 10-hour half-life temperature = 105 ° C., manufactured by NOF CORPORATION) 2.8
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) 220 as an inorganic filler
And 100 parts of the black and white inorganic filler-containing resin particles (C) obtained in the above Production Example (10) were added, and kneaded for 10 minutes with a kneader. The results of thickening are shown in Table 7.

Next, a granite-like acrylic artificial marble was obtained in the same manner as in Example 1. Table 7 shows the evaluation results of the appearance of the obtained molded product.

[Comparative Example 5] As shown in Table 5, t-butyl peroxybenzoate (manufactured by NOF CORPORATION, trade name Perbutyl Z, 10-hour half-life temperature =
The same method as in Example 7 except that (104 ° C) is used,
An acrylic BMC was obtained. The results of thickening are shown in Table 7.

Next, an acrylic artificial marble was obtained in the same manner as in Example 1. Table 7 shows the evaluation results of the appearance of the obtained molded product.

[Comparative Example 6] Methyl methacrylate 20
%, Styrene 15%, trimethylolpropane trimethacrylate 25%, and 100 parts of a mixture of the components (a) and (b) consisting of 40% of the polymethylmethacrylate (B-1) obtained in the above Production Example (9), T-Butylperoxy 2-ethylhexanoate (manufactured by NOF CORPORATION), trade name Perbutyl O, 10-hour half-life temperature =
0.5 parts of zinc stearate as an internal mold release agent, and aluminum hydroxide (manufactured by Showa Denko KK, trade name Hydilite H- as an inorganic filler).
310 parts) and 100 parts of the black and white inorganic filler-containing resin particles (C) obtained in the above Production Example (10) were added, and kneaded for 10 minutes with a kneader to obtain an acrylic premix. The results of thickening are shown in Table 7.

Next, an acrylic artificial marble was obtained in the same manner as in Example 1. Table 7 shows the evaluation results of the appearance of the obtained molded product.

[0104]

[Table 4]

[0105]

[Table 5]

[0106]

[Table 6]

[0107]

[Table 7]

Thickening A of Premix A: Thickening immediately after kneading, a premix having good handleability without stickiness was obtained. B: After kneading, it took 24 hours or more to age at room temperature and increase the viscosity to the required viscosity.

Gloss of molded products A: The gloss is extremely high. ◯: There is gloss. X: There is no gloss.

Surface smoothness of molded products ⊚: No pinholes and extremely high surface smoothness. ◯: There are some pinholes, but there is no practical problem.

Sharpness of molded product ⊚: Very clear and very excellent in design. ◯: Stones are slightly blurred, but there is no problem in practical use.

Irregularity of stone pattern of molded product A: There is no pattern unevenness and the design is very good. ◯: There is some pattern unevenness, but there is no practical problem.

Whitening of insert screw front side ⊚: There is no whitening, and the position of the insert screw is completely unknown from the front side. ○ +: There is no whitening and the position of the insert screw is almost unknown from the front side. ◯: There is no whitening, and if you look closely you can see the position of the insert screw from the front side, but there is no practical problem. ×: Whitening is severe, and the position of the insert screw can be seen at a glance from the front side.

Insert screw front side sink mark: There is no sink mark, and the position of the insert screw is completely unknown from the front side. Δ: There are some sink marks, and the position of the insert screw can be seen from the front side. X: The sink mark is severe, and the position of the insert screw can be seen at a glance from the front side.

Whitening on the front side of the thickness change part ⊚: There is no whitening, and the position of the thickness change part is completely unknown from the front side. ○ +: There is no whitening, and the position of the thickness change part is almost unknown from the front side. ◯: There is no whitening, and if you look closely, you can see the position of the thickness change part from the front side, but there is no practical problem. X: Whitening is severe, and the position of the thickness change portion can be seen at a glance from the front side.

Sink mark on the front side of the thickness change part: There is no sink mark, and the position of the thickness change part is completely unknown from the front side. Δ: There are some sink marks, and the position of the thickness change portion can be seen from the front side. X: The sink mark is severe, and the position of the wall thickness changing portion can be seen at a glance from the front side.

[0117]

As is apparent from the above examples, by using a peroxide having a specific structure as a curing agent, there is no occurrence of sink marks or whitening on the front side of insert screws or the wall thickness changing portion. It becomes possible to obtain an acrylic resin composition having excellent molding processability, and an acrylic premix useful as a raw material for an acrylic artificial marble. Furthermore, by using a polymer powder, it is suitable for high temperature molding. It becomes possible to obtain acrylic SMC or BMC which is excellent in molding processability and is particularly useful as a raw material for acrylic artificial marble, and the acrylic artificial marble obtained by using the acrylic SMC has high productivity. It has a good appearance and is very useful industrially.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing the shapes of molded articles obtained in Examples and Comparative Examples of the present invention.

[Explanation of symbols]

1 Insert screw: φ9mm × 11mm P Width: 200mm Q Length: 200mm T ₁ Thickness: 5mm T ₂ Thickness: 10mm T ₃ Thickness: 15mm

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yuichiro Kishimoto 4-60 Sunadabashi, Higashi-ku, Nagoya, Aichi Prefecture Mitsubishi Rayon Co., Ltd. Product Development Research Laboratory (56) Reference JP-A-10-287716 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C04B 26/06 C08F 265/06

Claims (13)

(57) [Claims] 1. A methyl methacrylate or (meth) acrylic monomer mixture (a), a polymethylmethacrylate or an acrylic copolymer (b), and a curing agent represented by the following general formula (I) ( An acrylic resin composition containing c). [Chemical 1] (In the _formula, R 1, _{R 3} has an alkyl group having 1 to 6 carbon atoms, _{R 2} represents an alkylene group having 1 to 6 carbon atoms.) 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 SMC containing the acrylic premix according to claim 2 and a polymer powder . 5. The acrylic premix according to claim 2.
And an acrylic resin containing a polymer powder
BMC. 6. The acrylic SMC according to claim 4 is used.
A method for producing an acrylic artificial marble, which comprises heating and pressurizing in a range of 0 to 150 ° C. 7. The acrylic BMC according to claim 5 is used.
It is characterized in that it is heated and pressure cured in the range of 0 to 150 ° C.
A method for manufacturing an acrylic artificial marble. 8. A method for producing an acrylic artificial marble, which comprises using the acrylic resin composition according to claim 1 to produce a molded article having a change in wall thickness. 9. A method for producing an acrylic artificial marble, which comprises insert-molding the acrylic resin composition according to claim 1. 10. The method for producing an acrylic artificial marble, wherein the production method according to claim 6 is an insert molding method. 11. A method for producing an acrylic artificial marble, characterized in that the acrylic artificial marble according to claim 6 is a molded product having a variable wall thickness. 12. A method for manufacturing an acrylic artificial marble, wherein the manufacturing method according to claim 7 is an insert molding method. 13. A method for producing an acrylic artificial marble, characterized in that the acrylic artificial marble according to claim 7 is a molded product having a variable wall thickness.