Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
1998-05-28
2001-01-16
Baxter, Janet (Department: 1752)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S534000, C524S458000, C524S460000, C524S710000, C524S786000, C264S077000
Reexamination Certificate
active
06174954
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a resin composition suitable for producing artificial marble excellent in moldability and heat resistance, and artificial marble obtained by molding the resin composition.
BACKGROUND OF THE INVENTION
A conventional hand lay up molding method and a spray up molding method have been substituted by a method in which a sheet molding compound (SMC) material or bulk molding compound (BMC) material respectively containing as a main component an unsaturated polyester resin is used since the molding work of this method is simple, and these materials such as SMC and BMC have been used for a bath tub and the like.
However, these materials containing as a main component an unsaturated polyester resin exhibit a problem in that they were inferior with regard to hot water resistance and durability since the materials hydrolyzed under alkaline condition.
In order to improve this problem, various methods were suggested.
For example, Japanese Patent Application Publication (JP-B) No. 5-13899 discloses a method for producing a natural grain-like article wherein (i) 100 parts by weight of a “monomer A” containing 20% by weight or more of a polyfunctional (meth)acrylate, (ii) 50 to 300 parts by weight of a “methacryl-based resin powder B” having a grit of 20 mesh or less and an average molecular weight of 50,000 to 200,000 and being derived from a monomer containing methyacrylates as an essential component, (iii) 0.5 to 2 parts by weight of a “curing agent C” for the monomer A, (iv) 100 to 500 parts by weight of an “inorganic filler D”, and optionally, (v) a coupling agent, a coloring agent and a reinforcing agent are mixed, kneaded and aged with heating at room temperature or at a temperature lower than the curing temperature to obtain a molding material which is in clay form or solid form at room temperature. The produced molding material is molded and cured under pressure with heating.
Japanese Patent Application Laid-Open (JP-A) No. 5-32720 discloses an acrylic resin premix comprising (i) 20 to 60% by weight of an unsaturated monomer containing methyl methacrylate as a main component, (ii) 80 to 40% by weight of an inorganic powder, and (iii) 1 to 25% by weight of a resin fine particle which has a degree of swelling in methyl methacrylate of 3 to 15 times and is insoluble in methyl methacrylate.
Japanese Patent Application Laid-Open (JP-A) No. 7-188505 discloses an acrylic resin premix comprising, (i) based 100 parts by weight of an “acrylic syrup A” comprising as main components an unsaturated monomer essentially composed of methyl methacrylate and a polymer essentially composed of a polymer of methyl methacrylate, (ii) 180 to 260 parts by weight of an “inorganic powder B” and (iii) 60 to 140 parts by weight of a “resin particle C” containing an inorganic powder, wherein the resin particle C is insoluble in methyl methacrylate, and shows an oil absorption in methyl methacrylate after one day of 40 to 100% by weight and a degree of swelling in methyl methacrylate of 2 times or less.
However, in the method of Japanese Patent Application Publication (JP-B) No. 5-13899, the methacryl-based resin powder having an average molecular weight of 50,000 to 200,000 is used as a resin component and, therefore, there are problems regarding handling properties. Stickiness of the surface after the kneading and aging is remarkable, shape stability after the kneading is not sufficient and the kneaded resin flows or is deformed when only left.
Further, all of the premixes described in Japanese Patent Application Laid-Open (JP-A) No. 5-32720 and Japanese Patent Application Laid-Open (JP-A) No. 7-188505 contain the unsaturated monomer component essentially composed of methyl methacrylate, can not suppress evaporation of methyl methacrylate, are deficient in stability when stored or left, and further, have a bad odor. Therefore, improvement has been desired not only in view of handling properties but also in view of working environments.
SUMMARY AND OBJECTS OF THE INVENTION
The present inventor has intensively studied the issues regarding a resin composition suitable for producing artificial marble, which has excellent handling properties, generates little odor in handling and can be easily molded. As a result, it has been found that a resin composition comprising an unsaturated monomer having at least two double bonds which can effect radical polymerization or a mixture of said unsaturated monomer and an unsaturated monomer copolymerizable with said unsaturated monomer, an inorganic filler, a cross-linked resin particle, a resin having a methyl methacrylate unit, and a radical polymerization initiator, respectively in specific amounts, has excellent handling properties, generates little odor in handling, and can be easily molded for producing artificial marble. The present invention has been accomplished on the basis of the above findings.
Thus, the present invention provides a resin composition comprising the components of:
(a) 10 to 40% by weight of (i) an unsaturated monomer having at least two double bonds which can effect radical polymerization or (ii) a mixture of said unsaturated monomer and an unsaturated monomer copolymerizable with said unsaturated monomer,
(b) 50 to 85% by weight of an inorganic filler,
(c) 1 to 20% by weight of a cross-linked resin particle,
(d) 0.1 to 20% by weight of a resin having a methyl methacrylate unit, and
(e) 0.01 to 5% by weight of a radical polymerization initiator.
The present invention further provides artificial marble obtained by heating and curing the resin composition.
The present invention still further provides a method for producing artificial marble in which said resin composition is heated at a temperature of 30 to 80° C. to obtain a compound in the form of clay, then, said compound is subjected to thermal compression molding at 80 to 200° C.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
A resin composition of the present invention comprises the components of:
(a) 10 to 40% by weight of (i) an unsaturated monomer having at least two double bonds which can effect radical polymerization or (ii) a mixture of said unsaturated monomer and an unsaturated monomer copolymerizable with said unsaturated monomer,
(b) 50 to 85% by weight of an inorganic filler,
(c) 1 to 20% by weight of a cross-linked resin particle,
(d) 0.1 to 20% by weight of a resin having a methyl methacrylate unit, and
(e) 0.01 to 5% by weight of a radical polymerization initiator.
In the present invention, Examples of the unsaturated monomer having at least two double bonds which can effect radical polymerization include allyl methacrylate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, 1,3-butylene glycol di(meth)acrylate, 1,6-hexane diol di(meth)acrylate, neopentyl glycol di(meth)acrylate, divinylbenzene, diallyl phthalate, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tri(meth)acrylate, tetramethylolmethane tetra(meth)acrylate, and the like. Here, the term “(meth)acrylate” represents both acrylate and methacrylate. Among them, the unsaturated monomer having at least two methacryloxy groups is preferred since there remains only a little amount of unsaturated monomer which has not reacted in the curing reaction thereof.
In the present invention, An unsaturated monomer copolymerizable with the unsaturated monomer having at least two double bonds which can effect radical polymerization can be used with the latter unsaturated monomer and is not restricted as long as it has such copolymerizable property, and can be appropriately selected for use. Examples of the unsaturated monomer copolymerizable with the unsaturated monomer having at least two double bonds which can effect radical polymerization include esters of methacrylic acid or acrylic acid with aliphatic, aromatic, alicyclic alcohol such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexy
Baxter Janet
Birch & Stewart Kolasch & Birch, LLP
Gilmore Barbara
Sumitomo Chemical Company Limited
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