JPH1045815A - Resin composition, artificial marble obtained by forming the same and production of the marble - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin composition suitable for easily producing an artificial marble less in discoloration and the artificial marble less in discoloration. SOLUTION: This resin composition contains 100 pts.wt. unsaturated monomer consisting of methylmethacrylate as a main component and/or an acrylic syrup, 2-120 pt.wt. compound having at least two epoxide groups is one molecule, 0.3-1.5 equivalent dicyanodiamide based on the epoxide group, 0.01-5 pt.wt. radical polymerization initiator, 30-800 pt.wt. inorganic filler, and as necessary a compound having an imidazole skeleton as a curing accelerator. The resin composition is polymerized at 30-100 deg.C after pouring the same into a mold to form a soft type acrylic resin, and then an artificial marble less in discoloration is obtained by forming the soft type acrylic resin with a heat-compression at 90-200 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition suitable for producing artificial marble having excellent moldability and heat resistance, and an artificial marble obtained by molding the resin composition.

[0002]

2. Description of the Related Art Sheet molding compound (SMC) and bulk molding compound (BMC) materials mainly composed of unsaturated polyester resin have been replaced by conventional hand lay-up molding methods or spray-up molding methods because of their simple molding work. And is used for applications such as bathtubs. However, these materials, which are mainly composed of unsaturated polyester resins, have a problem that they are inferior in hot water resistance and durability because they are hydrolyzed by alkali. Various methods have been proposed to improve this.

For example, Japanese Patent Publication No. Hei 6-2804 discloses that
Radical polymerizable monomer (A), thermoplastic resin (B) dissolved or dispersed in monomer (A), epoxy resin (C), polyfunctional carboxylic acid and / or anhydride (D) and inorganic material It comprises a filler (E), and the compounding ratio of these components is 5 to 75 parts by weight of the thermoplastic resin (B) and 10 to 100 parts by weight of the epoxy resin (C) based on 100 parts by weight of the radical polymerizable monomer (A). Parts and the inorganic filler (E) in the range of 100 to 1000 parts by weight and 1 equivalent of the epoxy resin (C) to 0.5 to 4.0 equivalents of the polyfunctional carboxylic acid and / or its anhydride (D) (however, An acid anhydride group is considered to be bifunctional.), And a resin composition for artificial marble is disclosed.

In Japanese Patent Publication No. 8-19210,
A radical polymerizable monomer (A), a thermoplastic resin (B), an epoxy resin (C), a polyfunctional carboxylic acid and / or an anhydride thereof (D), and an inorganic filler (E); B) having a functional group which dissolves or disperses in the radical polymerizable monomer (A) and reacts with the epoxy resin (C) or the polyfunctional carboxylic acid and / or its anhydride (D), The mixing ratio of the components is 100 parts by weight of the radical polymerizable monomer (A), 5 to 75 parts by weight of the thermoplastic resin (B), and 10 to 10 parts by weight of the epoxy resin (C).
100 parts by weight and an inorganic filler (E) 100 to 100
The polyfunctional carboxylic acid and / or its anhydride (D) is contained in an amount of 0 part by weight and 1 equivalent of the epoxy resin (C).
5 to 4.0 equivalents (however, acid anhydride groups are considered to be bifunctional)
Are disclosed.

[0005]

However, artificial marble obtained by molding the resin composition described in JP-B-6-2804 and JP-B-8-19210 may be colored yellow, Not always satisfactory. The present inventors have conducted intensive studies on artificial marble which is easy to mold and has little coloring. As a result, an unsaturated monomer mainly composed of methyl methacrylate, a compound having at least two epoxy groups in one molecule, radical polymerization initiation It has been found that by using dicyanodiamide to cure a compound having an epoxy group of a resin composition containing an agent and an inorganic filler, artificial marble with less coloring can be easily produced, and the present invention has been achieved. .

[0006]

That is, the present invention relates to a method for preparing 100 parts by weight of an unsaturated monomer mainly composed of methyl methacrylate and / or acrylic syrup, a compound having at least two epoxy groups in one molecule. To 120 parts by weight, 0.3 to 1.5 equivalents of dicyanodiamide based on the epoxy group, and 0.001 of a radical polymerization initiator.
A resin composition containing ５5 parts by weight and 30-800 parts by weight of an inorganic filler, and an artificial marble obtained by molding the resin composition.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The unsaturated monomer mainly composed of methyl methacrylate in the present invention refers to a mixture of an unsaturated monomer containing 50% by weight or more of methyl methacrylate and copolymerizable with methyl methacrylate. Examples of the unsaturated monomer copolymerizable with methyl methacrylate include esters of methacrylic acid or acrylic acid with aliphatic, aromatic, or alicyclic alcohols, and (meth) acrylic acids such as hydroxyalkyl esters. -Based monomers, styrene-based monomers, acrylonitrile, monofunctional unsaturated monomers such as vinyl acetate; 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-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, divinylbenzene, trimethylolpropanetri (meth) acrylate, tetramethylolmethanetri (meth) acrylate, tetramethylolmethanetetra (meth) acrylate And polyfunctional unsaturated monomers having a plurality of radically polymerizable double bonds in one molecule.

[0008] A so-called acrylic syrup in which a polymer component such as a polymer of methyl methacrylate is added to the unsaturated monomer mainly composed of methyl methacrylate can also be used. Examples of a method for containing a polymer component include a method of partially polymerizing an unsaturated monomer mainly containing methyl methacrylate, and dissolving a polymer component in a mixture of an unsaturated monomer mainly containing methyl methacrylate. And the like.

The compound having at least two epoxy groups in one molecule in the present invention includes, for example, glycidyl ether epoxy resins such as bisphenol A type epoxy resin, bisphenol F type epoxy resin and novolak type epoxy resin; Examples include a formula aliphatic epoxy resin and a glycidyl ester epoxy resin.

The compounds having at least two epoxy groups in one molecule include unsaturated monomers mainly composed of methyl methacrylate and / or acrylic syrup.
It is added in the range of 2 to 120 parts by weight with respect to 0 parts by weight. If the amount is less than 2 parts by weight, sufficient heat resistance cannot be obtained. Conversely, if the amount exceeds 120 parts by weight, problems such as a decrease in transparency and coloring of yellow occur.
The addition amount is preferably in the range of 2 to 120 parts by weight.

In the present invention, dicyanodiamide is used to cure a compound having at least two epoxy groups in one molecule. Dicyanodiamide is tetrafunctional per molecule, and the amount added is in the range of 0.3 to 1.5 equivalents based on the epoxy group of the compound having an epoxy group. If it is less than 0.3 equivalent, curing will be insufficient, and if it is more than 1.5 equivalent, coloring and the like will be remarkable, which is not preferable.

In the present invention, it is desirable to use a curing accelerator in addition to dicyanodiamide. As the curing accelerator, a compound having an imidazole skeleton is preferable. Examples of the compound having an imidazole skeleton include, for example, 2-
Methylimidazole, 2-ethyl-4-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 2-phenylimidazole, 1-benzyl-2-methylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl- 2-ethyl-4
-Methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-undecylimidazolium trimellitate, 1-cyanoethyl-2
-Phenylimidazolium trimellitate, 2-methylimidazolium isocyanurate, 2-phenylimidazolium isocyanurate, 2,4-diamino-6
[2-methylimidazolyl- (1)]-ethyl S-triazine, 2,4-diamino-6- [2-ethyl-4-methylimidazolyl- (1)]-ethyl-S-triazine, 2,4-diamino -6- [2-Undecylimidazolyl- (1)]-ethyl-S-triazine 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-dihydroxymethylimidazole, 1-cyanoethyl- 2-phenyl-4,5-di (cyanoethoxymethyl) imidazole, 1-dodecyl-2
-Methyl-3-benzylimidazolium chloride,
Examples thereof include 1,3-dibenzyl-2-methylimidazolium chloride and derivatives of these compounds. Among them, the use of a compound having a melting point of 60 ° C. or higher is preferred because storage stability is improved.

The amount of the imidazole compound to be added varies depending on the kind of the imidazole, but the amount of the imidazole compound can be determined by trial and error according to the curing time. Generally, the amount is at most 3 parts by weight based on 100 parts by weight of a compound having at least two epoxy groups in one molecule. Addition of more than 3 parts by weight is not preferable because coloring is observed.

In the present invention, a radical polymerization initiator is added to polymerize and cure unsaturated monomers mainly composed of methyl methacrylate and / or acrylic syrup. Examples of the radical polymerization initiator include 1,1′-azobis (cyclohexane-1-carbonitrile), 2,2′-azobis (2,4,4-trimethylpentene), and 2,2′-azobis (2-methylpropane). ), 2-cyano-2-propyrazoformamide, 2,2'-azobis (2-hydroxy-methylpropionate), 2,2'-azobis (2-methyl-butyronitrile), 2,2'-azobis Isobutyronitrile, 2,2′-azobis (2,4-dimethyl-valeronitrile), 2,2′-azobis (2
4-dimethyl-4methoxyvaleronitrile), 2,2 '
Azo compounds such as azobis [2- (2-imidazolin-2-yl) propane] and dimethyl 2,2′-azobis (2-methylpropionate); dicumyl peroxide, t-butylcumyl peroxide, T-butyl peroxide, benzoyl peroxide, diacyl such as lauroyl peroxide, dialkyl peroxide-based initiator; t-butyl peroxy-3,3,5-
Trimethylhexanoate, t-butylperoxylaurate, t-butylperoxyisobutyrate, t-butylperoxyacetate, di-t-butylperoxyhexahydroterephthalate, di-t-butylperoxyazelate, t-butylperoxy-2-ethylhexanoate, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, t-amylperoxy-2-ethylhexanoate, t-butylperoxy Peroxyester initiators such as oxypivalate; t-
Percarbonate-based initiators such as butylperoxyallyl carbonate and t-butylperoxyisopropyl carbonate; 1,1-di-t-butylperoxycyclohexane, 1,1-di-t-butylperoxy-3,
3,5-trimethylcyclohexane, 1,1-di-t-
And peroxyketal-based initiators such as hexylperoxy-3,3,5-trimethylcyclohexane. These radical polymerization initiators can be used alone or in combination of two or more.

These polymerization initiators are added in an amount of 0.001 to 5 parts by weight based on 100 parts by weight of the unsaturated monomer mainly composed of methyl methacrylate and / or acrylic syrup. If the amount is less than 0.001 part by weight, it takes a long time to carry out radical polymerization. If the amount exceeds 5 parts by weight, the unsaturated monomer mainly composed of methyl methacrylate and / or acrylic syrup is polymerized stably. It is not preferable because it becomes impossible.

The inorganic filler in the present invention is not particularly limited as long as it is insoluble in unsaturated monomers mainly composed of methyl methacrylate and / or acrylic syrup and does not hinder the polymerization reaction. Examples of such inorganic fillers include, for example, aluminum hydroxide, aluminum oxide, calcium carbonate, calcium silicate, calcium sulfate, magnesium hydroxide, silica, talc, clay, bentonite, and the like, but are not limited thereto. It is not something to be done. Aluminum hydroxide, magnesium hydroxide, and silica are preferred from the viewpoint of the appearance and physical properties of the acrylic artificial marble. These inorganic fillers are not limited to one kind, but may be used in combination of two or more kinds. In the present invention, glass fibers can be contained in addition to the above-mentioned inorganic filler. The material of the glass fiber is not particularly limited, and generally used alkali glass and non-alkali glass can be used.

The amount of the inorganic filler to be added is in the range of 30 to 800 parts by weight based on 100 parts by weight of the unsaturated monomer mainly composed of methyl methacrylate and / or acrylic syrup. When the amount is less than 30 parts by weight, an artificial marble-like appearance cannot be obtained, and when the amount is more than 800 parts by weight, unsaturated monomers mainly composed of methyl methacrylate and / or
Alternatively, when mixed with an acrylic syrup or an epoxy compound, the viscosity becomes extremely high, and the handleability is deteriorated.

Next, a method for producing artificial marble by molding and curing the above resin composition will be described. In general, the production of artificial marble includes a step of radically polymerizing an unsaturated monomer mainly composed of methyl methacrylate and / or an acrylic syrup, and a step of reacting a compound having at least two epoxy groups in one molecule with dicyanodiamide. And two steps.

The step of radically polymerizing an unsaturated monomer mainly composed of methyl methacrylate and / or an acrylic syrup is first of all, an unsaturated monomer mainly composed of methyl methacrylate and / or an acrylic syrup,
A compound having at least two epoxy groups in the molecule,
Dicyanodiamide, a radical polymerization initiator, an inorganic filler and, if necessary, a compound having an imidazole skeleton are mixed to obtain a slurry resin composition.

The slurry-like resin composition is usually injected into a polymerization cell composed of at least two opposed flat plates and a sealing material for sealing the periphery. The material of the flat plate mentioned here is not particularly limited as long as it does not dissolve or erode in unsaturated monomers mainly composed of methyl methacrylate. In particular, a glass plate, a metal plate, or the like may be used. In the case of a metal plate, a belt-type continuous flat plate can also be used.

After injection into the polymerization cell, the mixture is heated to 30 ° C. to 100 ° C. to perform radical polymerization. When the polymerization is performed at a temperature higher than 100 ° C., the moldability of the acrylic resin plate obtained after the polymerization is reduced. Therefore, the polymerization is preferably performed at a temperature not higher than 100 ° C. On the other hand, if the temperature is lower than 30 ° C., a long time is required for polymerization, which is not preferable.

After completion of the radical polymerization, at least two flat plates constituting the cell are removed to obtain a soft acrylic resin. In the case of producing a plate-shaped artificial marble, the temperature is further raised as it is, and a curing reaction between the compound having an epoxy group and dicyanodiamide can be performed to obtain an artificial marble plate. In addition, the above-mentioned soft acrylic resin is put into molding dies of various shapes, and the molding and curing reaction are performed by applying pressure and heating to obtain molded products of various shapes.

In order to carry out the curing reaction between the compound having an epoxy group and dicyanodiamide, a temperature of 90 ° C. to 200 ° C. is preferred. If the temperature is lower than 90 ° C., a long time is required for the curing reaction. Conversely, if the temperature is higher than 200 ° C., the acrylic resin is decomposed or colored, which is not preferable.

Further, the above resin composition is poured into a molding die, which is heated to 30 ° C. to 100 ° C. to undergo radical polymerization, and then the curing reaction between the compound having an epoxy group and dicyanodiamide is continued at a desired temperature. Can also be performed.

[0025]

According to the present invention, artificial marble with less coloring can be easily produced.

[0026]

EXAMPLES The present invention will be described below in detail with reference to examples, but the present invention is not limited to these examples. The degree of coloring of the artificial marble was determined by molding and curing in a molding die for a predetermined time, followed by heat treatment in a hot air drying path at 200 ° C. for 1 hour, and thereafter, a spectrocalorimeter # 80 (manufactured by Nippon Denshoku Industries Co., Ltd.) And the degree of yellowness (Y
I) was determined and evaluated.

Example 1 Methyl methacrylate 50 was placed in a 1 liter round bottom flask.
0 parts by weight and 0.005 parts by weight of azobisisobutyronitrile were added, the mixture was kept at 80 ° C. for 2 hours in a water bath, and then cooled to room temperature to obtain an acrylic syrup partially polymerized with methyl methacrylate. This acrylic syrup 5
Epolite 100MF as epoxy resin in 0 parts by weight
(Kyoeisha Chemical Co., Ltd.) 50 parts by weight, dicyanodiamide 10 parts by weight, azobisisobutyronitrile 0.0
5 parts by weight were added, followed by stirring and mixing. Further, 230 parts by weight of aluminum hydroxide (CW-325LV, manufactured by Sumitomo Chemical Co., Ltd.) was added and mixed to obtain a resin composition.

This resin composition was injected into a cell constituted by two glass plates having a thickness of 5 mm and a gasket made of vinyl chloride resin so that the gap between the glass plates was 3 mm,
The polymerization was carried out in a hot-air drying oven maintained at 6 ° C. for 6 hours. After cooling to room temperature, the glass plate was removed to obtain a soft acrylic resin. Next, the soft acrylic resin 130 is placed in a box-shaped mold having a width of 5 cm, a length of 12 cm, and a depth of 4 cm.
g, close the mold, 140 ° C, pressure 20kg / cm
Heat compression molding was performed for 60 minutes under the conditions of ² to obtain an artificial marble molded product. The appearance of the molded article was good, and the yellowness was 16.

Example 2 50 parts by weight of an epoxy resin, 50 parts by weight of Epolite 4000 (manufactured by Kyoeisha Chemical Co., Ltd.), 5 parts by weight of dicyanodiamide, and 0 parts of 2-ethylimidazole were added to 50 parts by weight of an acrylic syrup obtained in the same manner as in Example 1. Then, 0.5 parts by weight and 0.1 parts by weight of azobisisobutyronitrile were added, followed by stirring and mixing. Furthermore, 200 parts by weight of aluminum hydroxide (CW-325LV, manufactured by Sumitomo Chemical Co., Ltd.) and glass fiber (micro glass chopped strand, RES03-BM)
30 Nippon Glass Fiber Co., Ltd.) was added and mixed to obtain a resin composition. Using this resin composition, an artificial marble molded product was obtained in the same manner as in Example 1. The appearance of the molded product was good, and the yellowness was 18.

Comparative Example 1 Polymerization and molding were carried out in the same manner as in Example 1 except that 20 parts by weight of maleic anhydride was used instead of dicyanodiamide, to obtain an artificial marble molded product. Although the appearance of the molded article was good, it was colored yellow in appearance, and the yellowness was 40.

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Claims (6)

[Claims] 1. 100 parts by weight of an unsaturated monomer mainly composed of methyl methacrylate and / or acrylic syrup, 2 to 120 parts by weight of a compound having at least two epoxy groups in one molecule, and dicyanodiamide 0.3 to 1.5 equivalents based on the epoxy group, 0.001 to 5 parts by weight of the radical polymerization initiator and 30 to 50 parts by weight of the inorganic filler.
A resin composition containing 800 parts by weight. 2. The resin composition according to claim 1, comprising a compound having an imidazole skeleton as a curing accelerator for the compound having an epoxy group. 3. The resin composition according to claim 1, wherein the inorganic filler is aluminum hydroxide. 4. The method according to claim 1, wherein the inorganic filler is glass fiber.
The resin composition as described in the above. 5. An artificial marble obtained by molding the resin composition according to claim 1 or 2. 6. The resin composition according to claim 1, which is cast and polymerized at 30 ° C. to 100 ° C. to form a soft acrylic resin, and then the soft acrylic resin is cured at 90 ° C. to 2 ° C.
A method for producing artificial marble, characterized by performing hot compression molding at 00 ° C.