JPH09111085A - Resin composition, acrylic premix and production of acrylic artificial marble - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a resin composition for artificial marbles, etc., having excellent appearance by blending a syrup containing methyl methacrylate, etc., and polymethylmethacrylate, etc., with resin powder having a specific core/shell structure and a polyfunctional monomer. SOLUTION: (A) Acrylic syrup comprising methyl methacrylate or a monomer mixture containing methyl methacrylate as a main component and a polymethyl methacrylate or a polymer containing methyl methacrylate as a main component is blended with (B) resin polymer powder having a core/shell structure and having (15/85) to (85/15) weight ratio of core phase to shell phase and <=400000 weight-average molecular weight of the shell phase and (C) a polyfunctional monomer (e.g. trimethylolpropane trimethacrylate) to provide the objective resin composition useful for molding materials, especially a premix suitable for high temperature molding and excellent in moldability and processability, and for acrylic artificial marbles, etc., having excellent appearance.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a molding material, particularly an acrylic resin composition useful as a raw material for a premix which is stable in quality, excellent in handleability and molding processability, and has high productivity and good appearance. The present invention relates to a method for producing a simple acrylic artificial marble.

[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 touch and weather resistance. Widely used for counters such as kitchen counters, vanities, waterproof pans, and other construction applications. These are generally manufactured by a method in which a so-called slurry in which an acrylic resin syrup is dispersed with an inorganic filler is filled in a molding die, and is cured and polymerized at a relatively low temperature. However, since this acrylic resin 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 slurry 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, various studies have hitherto been made, for example, Japanese Patent Laid-Open No. 5-3.
2720 and JP-A-6-313019,
A molding material for artificial marble, which is obtained by mixing a cross-linking resin powder or a high molecular weight resin powder with an acrylic resin syrup, is disclosed.

[0004]

However, the molding materials as disclosed in these publications have a melting temperature, a time and a melting temperature at the time of adding the resin powder in the step of swelling or dissolving the resin powder in the acrylic resin syrup. Since the state of existence of the resin powder largely changes depending on factors such as agitation efficiency, a phenomenon such as non-uniformity of the presence of the resin powder is likely to occur, and it is difficult to obtain a stable quality premix. Further, in the appearance of the molded surface of the obtained artificial marble, there is a problem that spots due to the resin powder are likely to occur.

The object of the present invention is to produce an acrylic resin composition which is suitable for high temperature molding and is useful as a raw material for a premix which is excellent in molding processability, and an acrylic artificial marble which has high productivity and good surface appearance. It is about the method.

[0006]

DISCLOSURE OF THE INVENTION As a result of intensive studies made by the present inventors in view of the above problems of the prior art, the addition of a resin powder having a specific structure to an acrylic resin syrup is suitable for high temperature molding. The present invention has been completed by finding an acrylic resin composition useful as a raw material for a premix having excellent moldability and a method for producing an acrylic artificial marble having high productivity and good surface appearance.

That is, the present invention is an acrylic syrup comprising methyl methacrylate or a monomer mixture (a) containing it as a main component, and polymethyl methacrylate or a polymer (b) containing methyl methacrylate as a main component. (A), a resin polymer powder (B) having a core / shell structure, a resin composition containing a polyfunctional monomer (C), and the resin composition and an inorganic filler. The present invention relates to the following acrylic premix, and a method for producing an acrylic artificial marble, which comprises heating and curing the acrylic premix.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The acrylic syrup (A) used in the resin composition of the present invention comprises the above-mentioned components (a) and (b).
It consists of components.

The methyl methacrylate used in the acrylic syrup (A) of the present invention or the monomer mixture (a) containing the methyl methacrylate as a main component preferably contains methyl methacrylate in the range of 50 to 100% by weight. Unsaturated monomer or unsaturated monomer mixture. The content of the component (a) in the component (A) is not particularly limited, but workability when the resin composition of the present invention is used as a premix, and the premix as a raw material for artificial marble. In consideration of physical properties such as falling ball impact strength when used as, the range of 30 to 90% by weight is preferable. More preferably 40 to 80% by weight, still more preferably 50 to
It is in the range of 75% by weight.

Examples of the monomer other than methyl methacrylate used in the component (a) of the present invention include, for example, 1 to 1 carbon atoms.
(Meth) acrylic acid ester having 20 alkyl groups, cyclohexyl (meth) acrylate, glycidyl (meth) methacrylate, hydroxyalkyl (meth) acrylate, (meth) acrylic acid, (meth) acrylic acid metal salt, fumaric acid, Fumarate, maleic acid, maleate, aromatic vinyl, vinyl acetate,
(Meth) acrylic acid amide, (meth) acrylonitrile, vinyl chloride, maleic anhydride, etc. are mentioned. These may be used alone or in combination of two or more as required.

The polymethylmethacrylate used in the acrylic syrup (A) of the present invention or the polymer (b) containing methylmethacrylate as a main component preferably contains 50 to 100% by weight of methylmethacrylate. It is an acrylic polymer. Although the content of the component (b) in the component (A) is not particularly limited,
Considering workability when the resin composition of the present invention is used as a premix, and physical properties such as impact strength when this premix is used as a raw material for artificial marble, a range of 10 to 70% by weight is obtained. preferable. More preferably 20 to 60% by weight, still more preferably 25 to 50% by weight
Range.

The component (b) of the present invention may be a cross-linked polymer or a non-cross-linked polymer, and can be appropriately selected according to need, but the fluidity of the resin composition obtained and the mechanical strength of the molding material. Taking into account, the weight average molecular weight is 15,
It is preferably in the range of 000 to 300,000.
More preferably, it is in the range of 25,000 to 250,000.

As the constituents other than the methyl methacrylate of the component (b) of the present invention, the monomers used in the component (a) can be applied as they are. As the component (b) of the present invention, two or more kinds can be used in combination and, if necessary, a polyfunctional polymer can be contained. The component (b) of the present invention can be produced by a known polymerization method such as a solution polymerization method, a bulk polymerization method, an emulsion polymerization method or a suspension polymerization method.

The acrylic syrup (A) of the present invention may be one obtained by dissolving the above component (b) in the above component (a), or one obtained by partially polymerizing the above component (a), or The partially polymerized product may further contain the component (a).

The resin polymer powder (B) having a core / shell structure of the present invention is a component for giving a molded article obtained from the resin composition of the present invention a good appearance.

The component (B) of the present invention is a resin polymer powder having a so-called core / shell structure, which is composed of a core phase serving as a core and a shell phase serving as an outer shell. The core phase and the shell phase in the component (B) are different from each other in the chemical composition, structure, molecular weight and the like of the polymers forming them.

The amount of the component (B) used in the present invention is not particularly limited, but it is preferable to use 100 parts by weight of the component (A) of the present invention.
It is preferably in the range of 3 to 150 parts by weight. This is because when the amount of the component (B) used in the present invention is less than 3 parts by weight,
This is because the effect of the present invention is hard to be exhibited, and if it exceeds 150 parts by weight, it tends to be difficult to uniformly mix the component (B).

The particle size of the component (B) of the present invention is 1 to 250.
μm is preferred. This is because when the particle diameter is less than 1 μm, the handling property of the component (B) is deteriorated, and when it exceeds 250 μm, a speckled pattern is generated on the surface of the obtained molding material, and the appearance tends to be deteriorated. is there. More preferably 3 to 150 μm, further preferably 10 to 100
It is in the range of μm.

The weight ratio of the core phase and the shell phase of the component (B) of the present invention is preferably in the range of 15/85 to 85/15. If the weight ratio deviates from this range, the advantage of having the core / shell structure is lost, and a speckled pattern is generated on the surface of the obtained molded product, and the appearance tends to be deteriorated. The range is more preferably 25/75 to 75/25, and further preferably 30/70 to 70/30.

When the component (B) of the present invention is added to the component (A), the shell phase in the component (B) swells rapidly and uniformly, and the components (A) and (B) have excellent compatibility. Indicates. Thereby, the molding material comprising the resin composition of the present invention,
It develops a good appearance. In order for the shell phase in the component (B) to swell quickly and uniformly, the weight average molecular weight of the shell phase is preferably 400,000 or less. If the weight average molecular weight exceeds 400,000, a speckled pattern is generated on the surface of the obtained molded product, and the appearance tends to be deteriorated.

Examples of the constituent components of the core phase and shell phase of the component (B) of the present invention include (meth) acrylic acid ester having an alkyl group having 1 to 20 carbon atoms, cyclohexyl (meth) acrylate, glycidyl (meth). ) Methacrylate, 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,
Although maleic anhydride and the like can be mentioned, it is preferable that the shell phase contains methyl methacrylate as a main component in order to enhance the affinity with the component (A). These polymerizable monomers can be appropriately selected and used as necessary, and can be used alone or in combination of two or more kinds.

The method for producing the resin polymer powder (B) of the present invention is not particularly limited, but it can be obtained, for example, by a suspension polymerization method. It can also be obtained by subjecting the emulsion obtained by emulsion polymerization to treatments such as spray drying, freeze drying and salt / acid precipitation.

The polyfunctional monomer (C) of the present invention is a component for imparting strength, solvent resistance, dimensional stability and the like to the obtained molding material. The amount of the component (C) used in the present invention is not particularly limited, but when the strength, transparency, heat resistance and molding shrinkage of the obtained molding material are taken into consideration, 100 parts by weight of the component (A) of the present invention are used. It is preferably in the range of 3 to 40 parts by weight. If it is less than 3 parts by weight, it tends to be difficult to obtain the above effects, and if it exceeds 40 parts by weight,
The obtained molding material tends to be brittle.

Examples of the component (C) of the present invention include ethylene glycol dimethacrylate, propylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate, 1,4-butylene glycol dimethacrylate, and 1,6-hexanediol dimethacrylate. Methacrylate, dimethylolethane dimethacrylate, 1,1-dimethylolpropane dimethacrylate, 2,2-dimethylolpropane dimethacrylate, trimethylolethane tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, tetramethylolmethane tri (Meth) acrylate, tetramethylolmethane dimethacrylate, and (meth) acrylic acid and ethylene glycol, polyethylene glycol, propylene glycol, polypropylene Glycol, pentaerythritol, polyhydric esters of polyhydric alcohols dipentaerythritol, divinylbenzene, triaryl isocyanurate, aryl methacrylate, and the like. Among them, 1,3-butylene glycol dimethacrylate, 2,
2-Dimethylolpropane dimethacrylate, trimethylolpropane tri (meth) acrylate and ethylene glycol dimethacrylate are particularly preferred.

When the resin composition of the present invention is used as a molding material, inorganic fillers such as aluminum hydroxide, silica, fused silica, calcium carbonate, barium sulfate, titanium oxide, calcium phosphate, talc, clay and glass powder. Can be used as necessary. In particular, when the resin composition of the present invention is used as a premix for artificial marble, the inorganic filler is an essential component.
In this case, as the inorganic filler, aluminum hydroxide,
Silica, fused silica, glass powder are particularly preferred,
It is used in the range of 150 to 400 parts by weight with respect to 100 parts of the resin composition of the present invention.

When the resin composition of the present invention is used as a molding material, if necessary, benzoyl peroxide, lauroyl peroxide, t-butyl hydroperoxide, cyclohexanone peroxide,
Organic peroxides such as methyl ethyl peroxide, t-butyl peroxyoctoate, t-butyl peroxybenzoate and azobisisobutyronitrile, curing agents such as azo compounds, reinforcing materials such as glass fibers and carbon fibers, Various additives such as a colorant, a thickener, a low-shrinking agent and the like can be added to and mixed with the resin composition of the present invention.

The method for mixing the resin composition of the present invention and the constituents for obtaining the molding material using the same is not particularly limited as long as it is a method capable of efficiently mixing a substance having a high viscosity. For example, a kneader, a mixer, a roll, an extruder, or the like can be used.

By adding and mixing an inorganic filler, an additive and the like to the resin composition of the present invention, an acrylic premix which is particularly useful as a raw material for an acrylic artificial marble can be obtained. This acrylic premix has characteristics that it is not sticky, has good handleability, and is easy to measure. The acrylic artificial marble can be obtained by filling an acrylic premix in a molding die and heating and curing the acrylic premix. Specific examples of the heat and pressure curing include a compression molding method, an injection molding method, and an extrusion molding method, but are not particularly limited.

[0029]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to examples. All parts and percentages in the examples are by weight. -Physical properties of acrylic syrup (A) Weight average molecular weight: measured value by GPC method-Physical properties of resin polymer powder (B) Weight average molecular weight of shell phase: Polymer having the same composition as the polymer constituting the shell phase The homopolymerization is carried out under the same conditions as those for forming the shell phase in the above, and the weight average molecular weight of the obtained polymer is taken as the weight average molecular weight of the shell phase. The method for measuring the weight average molecular weight is the same as that for the acrylic syrup (A).

Average particle diameter: Measured using a laser diffraction / scattering type particle size distribution measuring device (LA-700, manufactured by Horiba Ltd.).

(1) Production Example of Resin Polymer Powder (B-1) A reaction apparatus equipped with a cooling pipe, a thermometer, a stirrer, a dropping device, and a nitrogen introducing pipe was used, and 1500 parts of pure water was used as a dispersion solvent. Using 600 parts of methacrylate as a polymerization component and 6 parts of sodium dodecylbenzene sulfonate as an emulsifier, n-
Charge 3 parts of dodecyl mercaptan as polymerization regulator,
It was heated to 70 ° C. with stirring under a nitrogen atmosphere. To this, 6 parts of potassium persulfate was added as a polymerization initiator to start emulsion polymerization. After confirming the polymerization peak, 20 parts of sodium formaldehyde sulfoxylate was added as a reducing substance. After that, the temperature was adjusted to 80 ° C., a solution prepared by dissolving 8 parts of t-butyl peroxide as a polymerization initiator in 400 parts of methyl methacrylate as a polymerization component was added dropwise over 3 hours, and the reaction was further maintained for 1 hour. After that, the reaction was terminated to obtain a resin polymer emulsion. The resulting emulsion was spray-dried using a spray dry (L-8 type, manufactured by Okawara Koki Co., Ltd.) to obtain a resin polymer powder (B-1) having a core / shell structure. The resin polymer powder (B-1) had an average particle diameter of 35 μm and a shell phase weight average molecular weight of 150,000.

(2) Production Example of Resin Polymer Powder (B-2) Core / core was prepared in the same manner as in the above (1) except that the amounts of methyl methacrylate initially charged and dropped were changed to 300 parts and 700 parts, respectively. A resin polymer powder (B-2) having a shell structure was obtained. The obtained (B-2) had an average particle diameter of 25 μm and a shell phase weight average molecular weight of 250,000.

(3) Production Example of Resin Polymer Powder (B-3) Core / core was prepared in the same manner as in the above (1) except that the initial charge and the drop charge of methyl methacrylate were changed to 800 parts and 200 parts, respectively. A resin polymer powder (B-3) having a shell structure was obtained. The average particle diameter of the obtained (B-3) was 33 μm, and the weight average molecular weight of the shell phase was 100,000.

(4) Production Example of Resin Polymer Powder (B-4) The same as (1) above except that the amount of t-butyl peroxide used in the dropping was 2 parts and the dropping time was changed to 2 hours. By the method, a resin polymer powder (B-4) having a core / shell structure was obtained. The obtained (B-4) had an average particle diameter of 40 μm and a shell phase weight average molecular weight of 300,000.

(5) Production Example of Resin Polymer Powder (B-5) In a reactor equipped with a cooling pipe, a thermometer, a stirrer, a dropping device, and a nitrogen introducing pipe, 1500 parts of pure water was used as a dispersion solvent, and methyl was used. 1000 parts of methacrylate as a polymerization component, 10 parts of sodium dodecylbenzene sulfonate as an emulsifier,
1 part of n-dodecyl mercaptan was charged as a polymerization modifier and heated to 70 ° C. under a nitrogen atmosphere with stirring. To this, 5 parts of potassium persulfate was added as a polymerization initiator,
Emulsion polymerization was started. After confirming the polymerization peak, the reaction was terminated to obtain a resin polymer emulsion. The obtained emulsion was spray-dried using spray dry (L-8 type, manufactured by Okawara Koki Co., Ltd.) to obtain a resin polymer powder (B-5) having no core / shell structure. The resin polymer powder (B-5) had an average particle diameter of 30 μm and a weight average molecular weight of 480,000.

(6) Production Example of Resin Polymer Powder (B-6) A core / shell structure was obtained in the same manner as in (5) above except that the amount of n-dodecyl mercaptan used was changed to 15 parts. A resin resin powder (B-6) which does not exist was obtained. The resin polymer powder (B-6) had an average particle diameter of 30 μm and a weight average molecular weight of 250,000.

(7) Production Example of Resin Polymer Powder (B-7) In the same manner as (5) above, except that 5 parts of 2,2-dimethylolpropane dimethacrylate were used as a crosslinking agent at the time of charging. A crosslinked resin polymer powder (B-7) having no core / shell structure was obtained. Resin polymer powder (B-
The average particle size of 7) was 30 μm.

(8) Example 1 A resin composition consisting of 100 parts of acrylic syrup consisting of 65% of methyl methacrylate and 35% of polymethyl methacrylate having a weight average molecular weight of 100,000 and 7 parts of trimethylolpropane trimethacrylate was cured. After adding 1.3 parts of t-butyl peroxytoctate (Perbutyl O, manufactured by NOF CORPORATION) as an agent and 1 weight part of zinc stearate as an internal mold release agent, aluminum hydroxide (Hydrite) as an inorganic filler was added. H-310, manufactured by Showa Light Metal Co., Ltd.) was added, and further, 10 parts of the resin polymer powder (B-1) obtained in the above (1) was added, and the mixture was sufficiently kneaded with a kneader to give a sticky feeling. An acrylic premix having good handleability was obtained.

Next, the obtained acrylic premix was filled in a 200 mm square flat mold and was heated and pressurized and cured for 10 minutes under the conditions of a mold temperature of 95 ° C. and a pressure of 50 kg / cm ² . An acrylic artificial marble having a thickness of 10 mm was obtained. The surface of the obtained artificial marble was a mirror surface without any defects, and the appearance was good.

(9) Examples 2 to 4 Acrylic premixes were obtained in the same manner as in Example 1 except that the resin polymer powders (B-2) to (B-4) were used, respectively. The resulting acrylic premix had no stickiness and was easy to handle. The acrylic artificial marble obtained by the same method as in Example 1 was in a mirror state with no defects and had a good appearance.

(10) Comparative Examples 1 to 3 An acrylic premix was produced in the same manner as in Example 1 except that resin polymer powders (B-5) to (B-7) were used, respectively. An acrylic artificial marble was obtained in the same manner as in Example 1. Each of the obtained acrylic artificial marbles had a speckled pattern on the surface and had a defect in appearance.

[0042]

As is apparent from the above examples, by using the acrylic resin composition of the present invention, it becomes possible to obtain a premix suitable for high temperature molding and excellent in moldability, Furthermore, the acrylic artificial marble produced using this has an excellent appearance and is very useful industrially.

Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display area C08F 220/20 MMV 7824-4J C08F 220/20 MMV

Claims (5)

[Claims] 1. An acrylic syrup (A) comprising methyl methacrylate or a monomer mixture (a) containing the same as the main component, and polymethyl methacrylate or a polymer (b) containing the methyl methacrylate as the main component, A resin composition comprising a resin polymer powder (B) having a core / shell structure and a polyfunctional monomer (C). 2. The resin composition according to claim 1, wherein the weight ratio of the core phase to the shell phase of the resin polymer powder (B) is in the range of 15/85 to 85/15. 3. The resin composition according to claim 1, wherein the weight average molecular weight of the shell phase of the resin polymer powder (B) is 400,000 or less. 4. An acrylic premix containing the resin composition according to claim 1 and an inorganic filler. 5. A method for producing an acrylic artificial marble, which comprises heating and curing the acrylic premix according to claim 4.