JP2882688B2 - Artificial marble and its manufacturing method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to artificial marble containing an inorganic filler such as aluminum hydroxide and a metal oxide such as colloidal silica. More specifically, the present invention relates to an artificial marble that is provided with excellent nonflammability without impairing the design properties (transparency, hiding properties, surface appearance) unique to artificial marble, and particularly suitable for building materials.

BACKGROUND ART So-called artificial marble, in which an inorganic filler such as aluminum hydroxide and magnesium hydroxide is blended with a resin such as an acrylic resin or an unsaturated polyester resin, is light in weight and has good workability while having a design property close to that of natural stone. Due to certain advantages, it is rapidly spreading mainly in interior materials, especially in the sanitary field.

Since these artificial marbles contain a high content of inorganic hydrates that also act as flame retardants, they are certified as flame retardant materials under the Building Standards Act of Japan. However, it cannot be used in places where the use of non-combustible or semi-combustible materials is required.

In order to solve this technical problem, aluminum hydroxide is combined with crushed stone of natural stone or other inorganic fillers, and the inorganic components are blended at a higher level to relatively reduce the resin content and make it non-combustible. An attempt to achieve the above has been proposed (Japanese Patent Publication No. 52-30290). Further, a combination of aluminum hydroxide and α-cristobalite (JP-A-60-226543) for the purpose of improving the balance between the transparency and whiteness of the molded product, and a hydroxide for preventing the sedimentation of inorganic substances. Combination of aluminum and silica fine particles (pyrogenic silica) (JP-A-3-28
For the purpose of improving processability and hot water resistance, a combination of methacrylic acid resin, aluminum hydroxide and silica (quartz) (Japanese Patent Application Laid-Open No. 60-245661) has been proposed. I have.

However, in any of these prior arts,
Other inorganic fillers combined with inorganic hydrates have been used in a highly aggregated state even if the particle size is on the order of microns or even if the primary particle size is on the order of nanometers. Therefore, it was not possible to simultaneously impart high flame retardancy and excellent design to artificial marble. In addition, if an attempt is made to mix a large amount of an inorganic component at the time of production, the viscosity of the mixture becomes too high.

Therefore, in the prior art, it was difficult to impart high flame retardancy while maintaining the excellent design properties of artificial marble.

DISCLOSURE OF THE INVENTION An object of the present invention is to provide a high level of flame retardancy without impairing the design properties (transparency, hiding properties, surface appearance) unique to artificial marble, while maintaining a high level of transparency even when the inorganic material is highly filled. Is to provide an artificial marble to which is added.

The present inventors have conducted intensive studies to achieve such an object, and as a result, have found that the above object can be achieved by artificial marble combining a radically polymerizable vinyl compound, a colloidal metal oxide and an inorganic filler. Reached the present invention.

That is, the present invention comprises a polymer (A) of a radical polymerizable vinyl compound (a), an inorganic filler (B) having an average particle diameter of 1 μm or more, and a colloidal metal oxide (C) having an average particle diameter of 1 to 100 nm. Wherein the metal oxide (C) is substantially uniformly dispersed in the polymer in the form of primary particles.

In addition, the method for producing artificial marble of the present invention has an average particle size of 1%.
In a dispersion comprising a colloidal metal oxide (C) having a thickness of about 100 nm and a dispersion medium, at least one silane compound (K) represented by the following general formula (i) is hydrolyzed and polycondensed. After modifying the surface of the colloidal metal oxide (C), the dispersion medium is replaced with a radically polymerizable vinyl compound (a), and further an inorganic filler (B) is added. This is a method characterized by polymerizing and curing a).

SiR ¹ _a R ² _b (OR ³ ) _c (i) (In the general formula (i), R ¹ and R ² are an ether bond, an ester bond, an amino group, a mercapto group, a halogen atom or a carbon atom.
A hydrocarbon group having 1 to 10 carbon atoms which may have a carbon double bond, R ³ is a hydrogen atom or an ether bond, an ester bond or a carbon atom having 1 to 5 carbon atoms which may have a carbon-carbon double bond. Ten
A and b are each an integer of 0 to 3, c is 4-ab, and represents an integer of 1 to 4. ) Further, another method for producing artificial marble of the present invention is as follows.
A dispersion medium in a dispersion liquid comprising a colloidal metal oxide (C) having an average particle diameter of 1 to 100 nm and a dispersion medium is mixed with a radical polymerizable vinyl compound having at least one hydroxy group in a molecule and a hydroxy group. After substitution with a radically polymerizable vinyl compound (a) containing at least one selected from the group consisting of radically polymerizable vinyl compounds having one or more epoxy groups in the molecule capable of generating the inorganic filler (B) The method is characterized by adding and radically polymerizing the radically polymerizable vinyl compound (a).

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a transmission electron micrograph of the artificial marble of the present invention.

FIG. 2 is a transmission electron micrograph of artificial marble according to the prior art.

BEST MODE FOR CARRYING OUT THE INVENTION The radically polymerizable vinyl compound (a) used in the present invention is not particularly limited, and various radically polymerizable monomers can be used. Specific examples include methacrylates such as methyl methacrylate and 2-ethylhexyl methacrylate; acrylates such as ethyl acrylate and butyl acrylate; unsaturated carboxylic acids such as acrylic acid and methacrylic acid; and maleic anhydride and itaconic anhydride. Acid anhydrides; maleimide derivatives such as N-phenylmaleimide and N-cyclohexylmaleimide; hydroxy group-containing monomers such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate and 2-hydroxypropyl methacrylate; vinyl acetate, vinyl benzoate Vinyl esters such as vinyl chloride, vinylidene chloride and derivatives thereof; nitrogen-containing monomers such as methacrylamide and acrylonitrile; epoxy-containing monomers such as glycidyl acrylate and glycidyl methacrylate. An aromatic compound having an ethylenically unsaturated bond in a molecule such as styrene and α-methylstyrene; and a dimer in a molecule such as ethylene glycol dimethacrylate, allyl acrylate, allyl methacrylate, divinylbenzene, and trimethylolpropane triacrylate. A crosslinking agent having at least one ethylenically unsaturated bond; an unsaturated polyester prepolymer derived from at least one polyvalent carboxylic acid containing an ethylenically unsaturated polycarboxylic acid and at least one diol; And a vinyl ester prepolymer derived by acrylic modification of the polymer.

Of these, methacrylates are preferred, and methyl methacrylate is particularly preferred. Further, two or more compounds which are compatible and copolymerizable can be used as a mixture. In that case, the content of at least one monomer selected from methacrylic acid esters is preferably 50% by weight or more, more preferably 70% by weight or more of the whole compound. Further, a polymer obtained by partially polymerizing a part of the monomer in advance may be used.

The content of the polymer (A) in artificial marble (hereinafter appropriately referred to as “molded product”) is determined by the properties of the intended molded product, but is 15 to 60% by weight, preferably 15 to 50% by weight. %.

Further, in order to express higher flame retardancy, the polymer (A) is mainly composed of a vinyl chloride-vinylidene chloride copolymer (hereinafter referred to as a “VC-VDC copolymer”) and methyl methacrylate. A mixture with a polymer (hereinafter appropriately referred to as “PMMA polymer”) can be used, and the mixture needs to be transparent or translucent in order to impart a sense of depth to the molded product. Is most preferred.

As a VC-VDC copolymer exhibiting such properties, the copolymer has a vinyl chloride content of 50 to 80% by weight and an intrinsic viscosity of 0.1 to 1.0 measured at 30 ° C. using tetrahydrofuran as a solvent. dl / g, preferably 0.2-0.5dl
/ g.

The content of the VC-VDC copolymer is 5 to 40% by weight, preferably 10 to 25% by weight, based on the total amount of the polymer (A). If the content of the copolymer is too small, a higher degree of flame retardancy cannot be achieved, while if it is too large, the properties such as heat resistance and weather resistance of the molded product are undesirably deteriorated.

Further, in a system using this VC-VDC copolymer together,
If colloidal antimony oxide is used as the colloidal metal oxide (C), the flame retardancy of the molded product can be further improved by a synergistic effect of the two.

Similarly, in order to express higher flame retardancy,
The polymer (A) may be a mixture of an acrylonitrile-styrene copolymer (hereinafter referred to as “AN-St copolymer”) and a PMMA polymer. This mixture needs to be transparent or translucent to give the molded product a sense of depth, and it is most preferable that the mixture be transparent. As the AN-St copolymer having such properties, the acrylonitrile content in the copolymer is 20 to 50 mol%.

The amount of the AN-St copolymer added to the PMMA polymer is 5 to 40% by weight, preferably 5 to 40% by weight, based on the total weight of the polymer (A).
10 to 25% by weight. If the added amount of the AN-St copolymer is too small, the flame retardancy hardly improves, and if it is too large, the properties such as weather resistance of the molded product are undesirably deteriorated.

Further, the polymer (A) is a copolymer comprising two or more monomers selected from the group consisting of cyclohexyl methacrylate, methyl methacrylate, 2-ethylhexyl methacrylate and styrene, and has a refractive index of room temperature. If the ratio is from 1.51 to 1.55, the molded product will have an increased transparency and an onyx appearance, and the water absorption of the polymer (A) will be reduced, thus improving the durability of the molded product. Can be done.

Similarly, as the polymer (A), an aliphatic polyfunctional methacrylate such as trimethylolpropane trimethacrylate 30
65 to 45% by weight of a monomer mixture having a ratio of 80 to 80% by weight and 70 to 20% by weight of an aromatic compound having an ethylenically unsaturated bond in a molecule such as styrene (the total amount of the polymer (A) is 100% %) And 35 to 55% by weight of an aromatic compound polymer having an ethylenically unsaturated bond in a molecule such as polystyrene.
(The total amount of the polymer (A) is 100% by weight), which has a refractive index of 1.55 to 1.57 at room temperature.
The use of a material having the above range can make the appearance of the molded product an onyx tone with a large transparent feeling. Further, in this case, the molded article produced by the pressure molding method has excellent transparency, and also has excellent water resistance and dimensional stability upon curing. Further, when a polymer obtained by curing a specific resin material and a specific partially crosslinked gel polymer as the polymer (A) is used, the heat resistance of the molded product can be improved. Such a polymer (A) is selected from the group consisting of methacrylates, α, β-ethylenically unsaturated monomer mixtures containing methacrylates as main components, and syrups containing the polymers. A mixture comprising 100 parts by weight of a resin raw material and a cross-linking agent having at least two or more methacryloyl groups in a molecule is partially polymerized so that the content of the polymer exceeds 80% by weight of the total polymer. Examples include a combination of 2 to 250 parts by weight of a partially crosslinked gel polymer in which the content of the polymer in the mixture is increased by 4 to 65% by weight. In addition, formic acid, oxalic acid, chloroacetic acid, malonic acid, citraconic acid, phthalic anhydride, succinic anhydride,
At least one acid selected from the group consisting of fumaric acid, phthalic acid, malic acid and phosphoric acid is converted into a polymer (A) 10
By adding 0.15 to 1.5 parts by weight per 0 parts by weight, coloring of the molded product can be suppressed.

Further, as the polymer (A), methacrylic acid esters containing methyl methacrylate as a main component containing 0.1 to 2% by weight of a crosslinking agent having two or more ethylenically unsaturated bonds in a molecule such as ethylene glycol dimethacrylate. 40
When the copolymer is made up of about 95% by weight and 5 to 60% by weight of an aromatic compound having an ethylenically unsaturated bond in a molecule such as styrene, the transparency and boiling water resistance of the molded product are improved. Can be.

For the purpose of improving the impact resistance of the molded product, an elastomer such as an acrylic elastomer can be added to the polymer (A).

The inorganic filler (B) used in the present invention is not particularly limited as long as it has an average particle diameter of 1 μm or more, is insoluble in the radically polymerizable vinyl compound (a), and does not hinder its polymerization and curing. Examples include aluminum hydroxide, magnesium hydroxide, calcium hydroxide, zirconium hydroxide, alumina, calcium carbonate, magnesium oxide, titanium oxide, barium sulfate, silica, quartz, talc, mica, clay, diatomaceous earth, and gypsum. , Powdered glass, montmorillonite, bentonite, pyrophyllite, kaolin, powdered chalk, marble, limestone, asbestos, mullite, aluminum silicate, aluminum stearate,
Calcium silicate, anhydrite, α-cristobalite, alumina white (general formula [Al ₂ SO ₄ (OH) ₄ .XH ₂ O.2Al (O
H) ₃ ] _n ), ettringite, fine powder obtained by crushing a fired body obtained by firing a mixture of clay and an inorganic substance capable of exhibiting a color after firing. These can be used alone or in combination of two or more. In order to impart flame retardancy and design to the molded product, aluminum hydroxide or magnesium hydroxide is preferred, and aluminum hydroxide is more preferred.

As the inorganic filler (B), those having an average particle diameter of 1 μm or more are used. The upper limit is not particularly limited, but if the particle size is too large, the dispersion becomes non-uniform, and the mixture is settled during molding and curing, which is not preferable. Usually 1 to 200
μm, preferably 1 to 100 μm, more preferably 1 to 80
It is in the range of μm.

The content of the inorganic filler (B) depends on the design properties (transparency, hiding properties, surface appearance), specific gravity, hardness, and the like of the target artificial marble.
It is determined by strength, heat resistance, flame retardancy, price, etc., but is 20 to 75% by weight in the molded product, preferably 45 to
75% by weight. If the content of the inorganic filler (B) is too large, excellent design properties unique to artificial marble are lost, and properties such as strength are undesirably reduced. On the other hand, if the content is too small, the excellent design properties unique to artificial marble will be lost, and properties such as hardness, heat resistance, and flame retardancy will also be poor.

Further, the surface of the inorganic filler (B) is previously treated with a silane-based coupling agent, a titanate-based coupling agent, an aluminum-based coupling agent, a stearic acid-based surface treatment agent, or the like, which is commonly used, before use. Can also. These treating agents can be used alone or in combination of two or more.

When alumina white (general formula [Al ₂ SO ₄ (OH) ₄ .XH ₂ O.2Al (OH) ₃ ] _n ) is used as the inorganic filler (B), the transparency of the molded product is increased, and the appearance of the molded product is increased. Can be made onyx-like.

Also, the inorganic filler (B) is used for a whiteness of 95 or more and an average particle diameter of
When a mixture of α-cristobalite and aluminum hydroxide having a size of 50 μm or less is used, the whiteness and transparency of the molded product can be improved.

Further, as the inorganic filler (B), a fine powder obtained by pulverizing a fired body obtained by firing a mixture of clay and an inorganic substance capable of exhibiting a color after firing can be used.

The above clays are ordinary clays, and include clay minerals such as phyllosilicate, pyrophyllite, talc, plum group, montmorillite group, vermiculite, ryokudeite group, kaolin group, inosilicate and the like, especially pyrophyllite. Various types of waxes represented by phyllite (phyllite) wax, kaolinite, sericite (sericite) wax are preferred.

As the inorganic substance capable of exhibiting a color after firing, in addition to what is called an inorganic pigment, for example, iron, lead, copper, nickel, cobalt, chromium, manganese, vanadium, molybdenum, antimony, tungsten, mercury, gold, carbon, and the like Simple substances and their oxides, hydroxides, carbonates, sulfides, chlorides, nitrates and sulfates are listed.

The mixing ratio of the clay and the inorganic substance and the firing method can be appropriately selected according to the desired color tone of the fine powder. Known methods can be applied to the firing method, usually 900 to 160
Conditions of baking at a temperature of 0 ° C. for 12 to 24 hours are employed.
The obtained fired body is finely pulverized by a fine pulverizer such as a ball mill or a roll mill to obtain a fine powder. The average particle size of the fine powder is preferably 50 μm or less, particularly preferably 20 μm or less.

As the colloidal metal oxide (C), a commercially available or prepared one in which the colloidal metal oxide (C) is substantially uniformly dispersed in the form of primary particles in various dispersion media is used. be able to. Examples thereof include colloidal silica, colloidal antimony oxide, colloidal alumina, colloidal titania, colloidal zirconia, and the like. Considering the price, availability, and properties of the molded product, colloidal silica, colloidal antimony oxide and colloidal alumina are preferred, and colloidal silica is most preferred.

Although the dispersion medium of the colloidal metal oxide (C) is not particularly limited, water, alcohols such as methanol and isopropyl alcohol, cellosolves, and dimethylacetamide are usually used. Particularly preferred dispersion media are alcohols, cellosolves and water.

The average particle size of the colloidal metal oxide (C) cannot be univocally determined because it affects the design properties (transparency, hiding properties, surface appearance) of the target artificial marble. , Usually 1 to 100 nm, more preferably 1 to 50 n
It is selected in the range of m.

The content of the colloidal metal oxide (C) cannot be defined uniquely because it is linked to the content of the inorganic filler (B) and affects the properties of the target artificial marble, but is usually 15 to 60% by weight of polymer (A), 20 to 75% by weight of inorganic filler (B), 1 to 50% by weight of colloidal metal oxide (C), based on the total weight of artificial marble
From 15 to 50% by weight of the polymer (A), 45 to 75% by weight of the inorganic filler (B), 5 to 30% by weight.
It is more preferred to select from the range of colloidal metal oxides (C) by weight.

A particularly preferable compounding ratio is that the total of the inorganic filler (B) and the metal oxide (C) is 50 to 85% by weight, and (B) /
(C) a weight ratio of 1.5 to 15, and the polymer (A) is obtained by polymerizing at least one compound selected from methacrylates based on the total weight of the polymer (A). Is contained by 50% by weight or more.

In the artificial marble of the present invention, the average particle size of 1 to 100 n
It is an essential condition that the m-type colloidal metal oxide (C) is substantially uniformly dispersed in the polymer (A) in the form of primary particles. That is, by dispersing a very small colloidal metal oxide (C) uniformly and stably substantially in the form of primary particles without agglomeration in a polymer, a higher level of difficulty can be obtained with the same amount of the inorganic component. Flammability or incombustibility can be imparted, and inorganic components can be filled at a higher level, and excellent design properties (transparency, hiding properties, surface appearance) unique to artificial marble are not impaired.

In order to stably and uniformly disperse the colloidal metal oxide (C) in the polymer (A) in the state of substantially primary particles without agglomeration, the metal oxide (C) is radically polymerizable vinyl compound ( During a), it is necessary to stably and uniformly disperse substantially in the state of primary particles. The following two methods can be exemplified as such a method.

In the first method, in a uniform dispersion of colloidal metal oxide (C) having an average particle diameter of 1 to 100 nm, the following general formula (i): SiR ¹ _a R ² _b (OR ³ ) _c (i) ( In the general formula (i), R ¹ and R ² represent an ether bond, an ester bond, an amino group, a mercapto group, a halogen atom,
A hydrocarbon group having 1 to 10 carbon atoms which may have a carbon double bond, R ³ is a hydrogen atom or an ether bond, an ester bond or a carbon atom having 1 to 5 carbon atoms which may have a carbon-carbon double bond. Ten
A and b are each an integer of 0 to 3, c is 4-ab, and represents an integer of 1 to 4. ), At least one silane compound (K) is hydrolyzed and polycondensed, and the reaction product is used to modify the surface of the colloidal metal oxide particles. This is a method of substituting with a vinyl compound (a).

The second method is that a dispersion medium of a uniform dispersion system of a colloidal metal oxide (C) having an average particle diameter of 1 to 100 nm is mixed with a radical polymerizable vinyl compound having at least one hydroxy group in a molecule and a hydroxy group. This is a method of substituting a radically polymerizable vinyl compound (a) containing at least one selected from the group consisting of radically polymerizable vinyl compounds having at least one epoxy group in a molecule capable of generating the following.

In the first method, an OR of at least one silane compound (K) represented by the general formula (i) in a uniform dispersion system of a colloidal metal oxide (C) having an average particle diameter of 1 to 100 nm. Most of the ^three groups are hydrolyzed. The silanol groups generated by hydrolysis of the silane compound (K) or the silanol groups of the condensation polymer formed by condensation polymerization of the silanol groups with the OH groups on the surface of the colloidal metal oxide (C) It is presumed that the condensation polymerization causes the colloidal metal oxide (C) to be coated (modified) with the reaction product of the silane compound (K), and the surface thereof to be hydrophobicized. As a result, the average particle size is 1 to 10
The colloidal metal oxide (C) having a thickness of 0 nm can be uniformly dispersed in the radically polymerizable vinyl compound (a) in a substantially primary particle state.

Specific examples of the silane compound (K) represented by the general formula (i) include, for example, tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane, ethyltrimethoxysilane, phenyltrimethoxysilane, dimethyldimethoxysilane, trimethyl Methoxysilane, trimethylethoxysilane, methyltriacetoxysilane,
Tetrakis (acryloyloxyethoxy) silane, tetrakis (methacryloyloxyethoxy) silane, β
Acryloyloxyethyldimethoxysilane, γ-acryloyloxypropylmethoxydimethylsilane, γ
Acryloyloxypropyltrimethoxysilane, β
-Methacryloyloxyethyldimethoxymethylsilane, γ-methacryloyloxypropylmethoxydimethylsilane, γ-methacryloyloxypropyltrimethoxysilane, vinylmethyldimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ -Aminopropyltriethoxysilane, γ-mercaptopropyldimethoxymethylsilane, γ-mercaptopropyltrimethoxysilane, p-vinylphenylmethyldimethoxysilane,
p-vinylphenyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-chloropropyltrimethoxysilane and the like.

Similarly to the above-mentioned alkoxysilane compound, a halogenated silane compound such as trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane, or phenyltrichlorosilane can be used as the silane compound that can be hydrolyzed to generate a silanol group.
Also, trimethylsilanol, triphenylsilanol,
It is to be understood that the use of compounds having one or more silanol groups in the molecule, such as methylsilanetriol, is also within the scope of the present disclosure.

By using at least one selected from these silane compounds, a metal oxide whose surface has been modified with a product of hydrolysis and condensation polymerization of the silane compound (hereinafter referred to as “surface-modified metal oxide”) can be obtained. The silane compound may be used in combination of two or more according to the purpose.
Hydrolysis and polycondensation may be performed by batch mixing, or hydrolysis and polycondensation may be performed by adding one by one step by step. When two or more silane compounds are used in combination, at least one reactive silane, such as γ-methacryloyloxypropyltrimethoxysilane, which can react with the radically polymerizable vinyl compound (a) during polymerization to form a chemical bond When the compound is used, the mechanical strength of the molded product can be improved.

What is important in the first method is that, when the dispersion medium of the surface-modified metal oxide is completely replaced with the vinyl compound (a), the surface-modified metal oxide becomes the same as the case of the metal oxide (C). And that they are substantially uniformly dispersed in the vinyl compound (a) in the state of primary particles.

In the hydrolysis and polycondensation reaction of the silane compound (K), water is preferably present in the reaction system. The effect of the proportion of water in the reaction system on the reaction rate is generally not particularly significant.However, when the amount of water is extremely small, hydrolysis is too slow to obtain a condensation polymer. It becomes difficult to be.

As a catalyst for performing the hydrolysis reaction of the silane compound (K), an inorganic acid or an organic acid can be used. As the inorganic acid, for example, hydrohalic acid such as hydrochloric acid, hydrofluoric acid, hydrobromic acid, sulfuric acid, nitric acid, phosphoric acid and the like are used. Examples of the organic acid include formic acid, acetic acid, oxalic acid, acrylic acid, methacrylic acid and the like.

A solvent can be used in the hydrolysis reaction system of the silane compound (K) in order to perform the reaction mildly and uniformly. As the solvent, a solvent that can make the silane compound, which is a reactant, water and a catalyst compatible with each other is desirable. Examples of such a solvent include water; alcohols such as ethyl alcohol and isopropyl alcohol; ketones such as acetone and methyl isobutyl ketone; ethers such as tetrahydrofuran and dioxane. As these solvents, the above-mentioned dispersion medium of the colloidal metal oxide (C) may be used as it is, or a new necessary amount may be added. The amount of the solvent to be used is not particularly limited as long as the reactant can be uniformly dissolved, but if the concentration of the reactant is too low, the reaction rate may be significantly reduced. The hydrolysis and polycondensation reaction of the silane compound (K) is carried out at a temperature of about room temperature to about 120 ° C. for 30 minutes.
The reaction is carried out for about 1 minute to 24 hours, preferably at about room temperature to about the boiling point of the solvent for about 1 to 10 hours.

The mixing ratio of the metal oxide (C) and the silane compound (K) represented by the general formula (i) is not particularly limited, but is based on 100 parts by weight of the solid content of the colloidal metal oxide (C). , The silane compound (K) is preferably 0.1 to 2000 parts by weight,
A range of 1 to 1000 parts by weight is more preferred.

The method for substituting the dispersion medium of the dispersion liquid of the surface-modified metal oxide thus obtained with the radically polymerizable vinyl compound (a) is not particularly limited. A method of directly mixing a radically polymerizable vinyl compound (a) with a dispersion liquid that is uniformly dispersed and then removing a dispersion medium and water from the mixture liquid, a dispersion medium containing a surface-modified metal oxide and water. Is performed by a method of adding the radically polymerizable compound (a) while removing the compound. In any case, it is necessary to replace the dispersion medium with the vinyl compound (a) without depositing the colloidal surface-modified metal oxide as a solid.

On the other hand, the second method uses a specific radically polymerizable vinyl compound as the radically polymerizable vinyl compound (a) so that the colloidal metal oxide (C) can undergo radical polymerization without any special treatment. This is a method of uniformly dispersing substantially in the state of primary particles in the vinyl compound (a).

Such a specific radically polymerizable vinyl compound is a compound having one or more hydroxy groups in a molecule, and is a compound which can be copolymerized with another radically polymerizable vinyl compound (a), and further includes a colloid. It is a compound having compatibility with the dispersion medium of the dispersion system in which the metal oxide (C) in the form of particles is substantially uniformly dispersed in the form of primary particles. Specific examples thereof include 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, and 2-hydroxypropyl methacrylate. Further, a radically polymerizable vinyl compound having at least one epoxy group in a molecule capable of easily generating a hydroxy group by ring opening can also be used. Specific examples thereof include glycidyl acrylate and glycidyl methacrylate.

These specific radically polymerizable vinyl compounds alone,
Alternatively, by using a mixture of two or more kinds in an amount of 0.1 to 100% by weight based on the polymer (A) of the radically polymerizable vinyl compound (a), the colloidal metal oxide (C) is aggregated, It can be uniformly dispersed in the vinyl compound (a) substantially in the form of primary particles without forming a structure.

Also in the case of the second method, the colloidal metal oxide (C) is produced in the same manner as in the first method.
Can be replaced with the vinyl compound (a) in a state where is not precipitated as a solid.

The method of molding and polymerizing and curing the radically polymerizable vinyl compound (a) for obtaining the artificial marble of the present invention is not particularly limited, but includes casting, pressure molding, injection molding, and extrusion molding. Etc. can be applied. In particular, as described above, since the colloidal metal oxide (C) is substantially uniformly dispersed in the polymer (A) in the state of primary particles, the total inorganic component is highly blended in the mixture for artificial marble. Taking advantage of the property that the viscosity does not increase even when the mixture is used, a mixture of the three components (A), (B) and (C) or a mixture containing other additives is used as a casting raw material to produce artificial marble. It can be manufactured using a casting method generally used as a method as it is.

In addition, a mixture comprising the three components (A), (B) and (C) or a mixture containing other additives is subjected to an appropriate thickening action or partially advanced by a polymerization curing reaction, It is possible to use various heating and pressure molding methods such as pressure molding method, injection molding method, extrusion molding method, transfer molding method, etc. it can.

As an example of the casting molding method, first, the colloidal metal oxide (C) or the surface-modified metal oxide is substantially primary-polymerized in the radically polymerizable vinyl compound (a) by the first method or the second method. After preparing a dispersion liquid which is uniformly dispersed in the state of particles, the radical polymerization initiator is dissolved, and then the inorganic filler (B) is dispersed to form a casting raw material, which is polymerized and cured.

As the radical polymerization initiator used here, a usual radical polymerization initiator of 0.001 to 2% by weight based on the weight of the polymer (A) is used. Azo compounds such as 2,2'-azobis (isobutyronitrile) and 2,2'-azobis (2,4-dimethylvaleronitrile); organic peroxides such as benzoyl peroxide and lauroyl peroxide; and redoxs thereof. The polymerization initiators and the like are examples of such initiators, and these can be used alone or in combination. When the polymerization initiator is an organic peroxide, a tertiary amine can be used as a polymerization accelerator. Further, for example, a hemi-ester of maleic acid obtained by reacting a saturated tertiary alkyl peroxymaleic acid such as t-butyl peroxymaleic acid with a basic metal compound, water, ethylene glycol dimercaptoacetate as a polymerization accelerator, A system in which a mercaptan compound such as the above, an oxoacid salt of sulfur or a sulfur activator which is a salt thereof, or the like can be used. These polymerization initiator systems can be appropriately selected depending on polymerization curing conditions (temperature, time, cost, etc.) desired by the manufacturer.

This casting raw material is sealed with a gasket around the periphery, injected between two opposing inorganic glass plates or metal plates and heated (cell casting method), or two metal plates traveling at the same speed in the same direction A method of continuously injecting and heating from the space sealed with an endless belt made of gas and a gasket, or from the upstream of the space sealed with one metal endless belt, one resin film and a gasket (continuous casting method) ) And the like.
At this time, the surface of the inorganic glass plate or the metal plate may be covered with a resin film such as polyvinyl alcohol or polyester in consideration of the mold release property and design property of the molded product.

Further, by adding an acid such as formic acid or acetic acid to the casting raw material for casting in an amount of 0.001 to 5% by weight based on the weight of the molded product, the difference in color tone between lots can be eliminated.

Furthermore, in the radical polymerizable vinyl compound (a), a prepolymer of methyl methacrylate having a molecular weight of 20,000 to 70,000 is present in an amount of 35 to 55% by weight based on the weight of the polymer (A), so that the methyl at the early stage of curing can be obtained. Since the methacrylate prepolymer forms a film on the open surface and suppresses volatilization of the vinyl compound (a) monomer, it is possible to produce a molded product by an open casting method.

Also, based on the weight of the molded product,
0.1-5 wt% of an alkyl acid phosphate (formula _{(C n H 2n + 1 O} ) m P (O) (OH) 3-m, where n is an integer of 8 to 13, m
Is 1 or 2), it is also possible to improve the releasability.

As for the pressure molding method, the injection molding method and the transfer molding method, various devices used in each method can be applied. Mold shape of the molded article,
Depending on the physical properties of the artificial marble mixture used, the molding temperature is 90-180 ° C, preferably 100-150 ° C, and the molding pressure is 20-5.
00 kg / cm ² , preferably 20-250 kg / cm ² , molding time is 1-3
It can be selected in the range of 0 minutes, preferably 2 to 20 minutes. Further, since volume shrinkage occurs with polymerization, it is preferable that the mold used has a structure capable of reducing the volume of the cavity in the thickness direction with volume shrinkage.

Further, by adding resin fine particles which are insoluble in the monomer (a) and have a swelling property to a molding material which is a mixture of the three components (A), (B) and (C), the molding material becomes sticky. And a molded product can be imparted with excellent transparency and mirror surface transferability.

By using a combination of a radical polymerization initiator having a 10-hour half-life temperature of 50 ° C or lower and a radical polymerization initiator of 70 ° C or higher as a polymerization initiator, the handleability of the molding material is improved, and the heat resistance of the molded product is further improved. It is also possible to improve the properties and chemical resistance and suppress surface defects such as sink marks and fiber shows.

When the polymer (A) contains a hydroxy group-containing polymethyl methacrylate-based copolymer having 2-hydroxyethyl methacrylate or the like as a copolymer component and a polyisocyanate, the molded article can be provided with weather resistance and ultraviolet resistance. Moreover, generation of cracks can be suppressed.

A thermoplastic polymer having a low solubility in the vinyl compound (a) and an average molecular weight of about 28 × 10 ⁴ is converted into a vinyl compound (a)
By being present inside, shrinkage during heat curing can also be suppressed.

In addition, by coexisting a crosslinked polymer fine powder obtained by emulsion polymerization of a methacrylic monomer in the vinyl compound (a), water resistance is imparted to the molded product, and cracks are also generated during curing. It can also be suppressed.

Further, when the artificial marble of the present invention is manufactured by various manufacturing methods, known additives such as a flame retardant, a coloring agent, and a reinforcing agent can be mixed with the molding material and used as long as the effects of the present invention are not impaired. .

For the purpose of imparting higher flame retardancy, a flame retardant (D) which is usually used can be further added. The flame retardant (D) is a flame retardant generally used for flame retarding plastics. Examples of such a flame retardant include perchlorocyclopentadecane, chlorendic acid, chlorinated paraffin, chlorinated polyethylene, and vinyl chloride resin. Chlorine-based flame retardants, brominated flame retardants such as decabromodiphenyl oxide, tetrabromobisphenol-A, and polydibromophenylene oxide; phosphorus-based flame retardants such as phosphate esters and red phosphorus; and inorganics such as nitrated guanidine and zinc borate. And the like.

Further, in order to satisfy the consumer's demand, it is preferable to have many colors, and in that case, the molded article is colored without impairing the design properties (transparency, hiding property, surface appearance) peculiar to artificial marble. It is necessary. As a coloring agent therefor, an iron oxide pigment (E) having an average particle diameter of 10 μm or less may be used in an amount sufficient to give a desired color. When a particle having a particle diameter of more than 10 μm is used, a molded product having desired properties may not be obtained. The iron oxide pigment (E) is satisfactorily dispersed in a suitable dispersant, for example, a soybean oil epoxide resin or the like, and the polymer (A), the inorganic filler (B) and the colloidal metal oxide (C) are dispersed. It is advisable to add the polymerizable mixture consisting of before curing.

As another colorant, a strong, weather-resistant short fiber such as nylon, aramid, acrylic, polyester, polyolefin, or natural fiber is colored to a desired color by adding a dye or pigment (F). Is mentioned.

The amount of the colored short fiber (F) added in the molded product depends on the amount of the molded product.
It is 0.01 to 2% by weight, preferably 0.05 to 1% by weight, and the fiber length is usually 0.2 to 13 mm, preferably 0.2 to 3.5 mm.
However, fibers longer than this range, for example fibers up to about 25 mm, can also be added. In addition, colored short fiber (F)
The fineness is preferably 1 to 300 denier, more preferably 1 to 48 denier.

In particular, when giving a black spot pattern to a molded product, black carbon particles (G) such as coal, coke, charcoal, activated carbon, carbon black, and other amorphous carbon can be used, and in particular, activated carbon can be used. preferable.

There is no particular limitation on the shape of the carbon particles (G),
In order to make the black speckle pattern in the molded product uniform, the shape has a ratio of the maximum width to the minimum width of 7 or less, preferably 5 or less, more preferably 3 or less.

The size and amount of the carbon particles (G) are also related to the desired properties of the molded product and cannot be uniquely determined. However, regarding the size, if the particles are too small, they cannot be visually identified as black spots. , Its maximum width is 0.05mm
It is preferably at least 0.1 mm, more preferably at least 0.15 mm. The amount of addition is 0.01 to 10% by weight, preferably 0.1 to 5% by weight, based on the total amount of the molded product.
If the addition amount is too small, the number of black spots is small, so that the spot pattern becomes unclear. If the addition amount is too large, the entire molded product is uniformly colored black, which is not preferable.

In addition, especially when giving a granite-like pattern to molded products,
Opaque particles (H) having a minimum dimension of 200 μm or more and an optical density of 2.0 or more for visible light; translucent particles having a minimum dimension of 200 μm or more and an optical density of 2.0 to 0.1 for visible light; // Optical density is 0.
At least one type of particles (I) selected from the group consisting of transparent particles less than 1 can be further added to the artificial marble of the present invention.

Incidentally, the optical density, G, R and B transparency when a visible light in the wavelength range of 400 to 800 nm was transmitted using a spectrophotometer with respect to a sample having a thickness of 0.24 mm, and the following formula was used. Refers to the value obtained. Here, Ii is the incident light intensity, and It is the transmitted light intensity.

Optical density = log ₁₀ (Ii / It) Both particles (H) and (I) have a minimum size of 200 μm.
m, preferably 250 μm or more, and most preferably each of the minimum, average and maximum particle size is 250
50005000 μm. However, for certain aesthetic effects, particles having a particle size much larger than 5000 μm in their largest dimension, for example 6 to 13 mm or more, can be present. However, at that time, it is necessary that the maximum particle size is set so as not to settle in the molded product and cause significant deformation of the molded product.

Examples of the opaque particles (H) include calcined talc, magnetite, goethite, and anthracite. Also, chips obtained by adding various fillers or pigments to various insoluble or cross-linked polymers such as polypropylene, phenolic resin, acrylic resin, and polyvinyl ester can be used.

On the other hand, the translucent particles and / or the transparent particles (I) are made of natural or synthetic minerals, such as, for example, liquorite, mica, wollastonite (wollastonite) or insoluble or cross-linked polymers with the addition of pigments or dyes. Chips can be used.

The addition amount of the opaque particles (H), the translucent particles and / or the transparent particles (I) is 1 to 25% by weight based on the total weight of the molded product.
The opaque particles (H) are more preferably 5 to 15% by weight, while the translucent particles and / or the transparent particles (I) are more preferably 5 to 15% by weight.

Similarly, natural stone-like pattern (stone-grain pattern) on the molded product
Is applied, substantially transparent particles (J) composed of the resin composition and the inorganic filler can be further added to the artificial marble of the present invention.

Here, “substantially transparent” means that the particles (J) have a design-like transparency, and the preferred state is according to JIS K-7105. Two
The value when the parallel light transmittance of a sheet having a thickness of mm is measured by the measurement method A is 8% or more, and more preferably 10% or more.

One preferred example of the resin composition of the transparent particles (J) is a copolymer of unsaturated polyester and styrene. The unsaturated polyester can be produced by a polycondensation reaction of an unsaturated dicarboxylic acid such as maleic acid or fumaric acid with a glycol such as ethylene glycol or diethylene glycol. Another preferred example is polybenzyl methacrylate or a polymer having benzyl methacrylate as a main structural unit. Preferred examples of the compound copolymerized with benzyl methacrylate include compounds having a plurality of polymerizable double bonds in the molecule, such as methacrylates other than benzyl methacrylate, styrene, and ethylene glycol dimethacrylate. Of these, more preferably 50 to 70% by weight of unsaturated polyester
Copolymer of styrene and 30 to 50% by weight, or copolymer of 90 to 99.9% by weight of benzyl methacrylate and 0.1 to 10% by weight of a compound having a plurality of polymerizable double bonds in a molecule such as ethylene glycol dimethacrylate. It is a polymer.

On the other hand, examples of the inorganic filler added to the transparent particles (J) include aluminum hydroxide, calcium hydroxide, magnesium hydroxide, powder talc, powder quartz, fine silica,
Diatomaceous earth, gypsum, powdered glass, clay mineral, powdered chalk, marble, limestone, asbestos, aluminum silicate,
Aluminum stearate, mullite, calcium silicate, anhydrite, etc. Of these, preferred are aluminum hydroxide, calcium hydroxide and magnesium hydroxide, and most preferred is aluminum hydroxide. These hydroxides release water of crystallization at high temperatures, and act particularly effectively to improve the flame retardancy of artificial marble.

The particle size of the inorganic filler is preferably from 1 to 150 μm, since it affects the translucency of the transparent particles (J) and the increase in viscosity when mixed with the polymerizable resin material, and the central particle size of the particle size distribution is preferably 1 to 150 μm. Is desirably 10 to 100 μm.

Regarding the amount of the inorganic filler to be added, excessive filling causes a decrease in the strength of the transparent particles (J) and tends to cause a decrease in transparency. Therefore, the addition amount of the inorganic filler in the transparent particles (J) is preferably 40 to 85% by weight based on the weight of the particles (J). In addition, those obtained by treating the surface of the inorganic filler with, for example, a silane coupling agent, a stearic acid surface treatment agent, or the like can also be handled.

Various additives other than the inorganic filler may be added to the transparent particles (J). As examples, pigments, coloring agents such as dyes,
There are ultraviolet absorbers, flame retardants, release agents, thickeners and the like.

Transparent particles (J) also take into account the danger of dust explosion due to the generation of static electricity in the particle transport process and pulverization process, causing the adhesion and aggregation of particles, the incorporation of foreign matter, and the like, and the occurrence of discharge phenomena. Those having a small electrostatic charge amount are preferred.

The larger the size of the transparent particles (J), the closer to the appearance of natural stone, the more difficult the production process of artificial marble. That is, when the artificial marble in which the transparent particles (J) are dispersed is ground to a depth of half the particle diameter of the particles (J), the particles (J) are drawn out to the surface of the artificial marble, and a more preferable appearance is obtained. Is obtained, so that the smaller the size of the particles (J), the easier the grinding. For this reason, the size of the particles (J) is preferably 0.2 to 5 mm.

As a method for producing the particles (J), a method in which an inorganic filler is uniformly dispersed in a polymerizable resin material and bulk polymerization is performed, and then a pulverizer is used to pulverize the inorganic filler, or the inorganic filler is added to the polymerizable resin material. Examples include a method of uniformly dispersing and suspending and polymerizing in an aqueous medium, and a method of uniformly dispersing the inorganic filler in the polymerizable resin material and performing bulk polymerization, followed by grinding with a grinder. preferable.

The amount of the transparent particles (J) to be added is preferably 1 to 25% by weight based on the total weight of the molded product.

Further, a glass fiber filler can be used in combination for the purpose of imparting further impact resistance to the molded product, but it is necessary to keep in mind that the design of the molded product may be impaired.

Further, depending on the purpose, various additives such as a flame retardant, a coloring agent, a reinforcing agent, an ultraviolet absorber, a heat stabilizer, and a release agent other than those described above may be added to the artificial marble of the present invention.

INDUSTRIAL APPLICABILITY The artificial marble of the present invention has a high level of flame retardancy, so that it can be applied to interior and exterior materials of buildings. In addition, conventionally known uses of artificial marble, for example, sanitary goods such as kitchen counter tables, cabinet panels, desktops, bar counter tops, cupboard panels, wash bowls, wash tops, bath units, toilet units, and toiletries It can be applied to living goods such as a table, a living table, a closet panel, and a furniture top.

Hereinafter, the present invention will be described more specifically with reference to examples.
In the examples, “parts” means “parts by weight” unless otherwise specified.

Here, regarding flame retardancy, for a sheet with a thickness of 3 mm, J
The oxygen index was measured and evaluated according to IS K-7201. The design was evaluated visually.

Example 1 In a glass flask with stirring blades, 5 parts of trimethylmethoxysilane and 200 parts of colloidal silica dispersed with isopropyl alcohol (average particle diameter: about 15 nm, silica content: 30% by weight, manufactured by Nissan Chemical Co., Ltd., trade name: IPA-ST) Was added, and 5 parts of a 0.1N hydrochloric acid aqueous solution was added with stirring, and the temperature was raised to 50 ° C. 2
After a period of time, while distilling off the volatile components at 40 ° C. under reduced pressure using a rotary evaporator, methyl methacrylate (hereinafter abbreviated as MMA) is added at the same rate as the distillation of the volatile components, and finally the dispersion medium is completely replaced with MMA. The total amount was 120 parts. The obtained colloidal silica dispersion was transparent and hardly increased in viscosity because the surface-modified colloidal silica was substantially uniformly dispersed in MMA in the form of primary particles.
The silica content calculated from the ash content after baking this dispersion in a crucible was 52% by weight.

After dissolving 0.25 part of 2,2'-azobis (2,4-dimethylvaleronitrile) (hereinafter abbreviated as AVN) in 100 parts of this dispersion, aluminum hydroxide (average particle diameter 44 μm, Nippon Light Metal Co., Ltd.) (BW-33, trade name) was added and mixed with a stirrer to prepare a casting raw material. This casting raw material contains 21% by weight of silica solids and 60% by weight of aluminum hydroxide (hereinafter abbreviated as "ATH").

The prepared casting material is reduced in pressure to remove dissolved air, and is formed of a gasket and two stainless steel plates (the surface of which is covered with a polyester film), and is set in a cell which is previously set to have a thickness of 3 mm. Poured into. Thereafter, polymerization was carried out at 80 ° C. for 2 hours and at 130 ° C. for 2 hours to form a target artificial marble.

Observation of the obtained ultrathin section of artificial marble with a transmission electron microscope confirmed that the colloidal silica was uniformly dispersed. This artificial marble was excellent in both transparency and depth, exhibited excellent design with a beautiful surface appearance, and exhibited an extremely excellent flame retardancy with an oxygen index of 90 or more (above the measurable upper limit). . Notification of Ministry of Construction, Japan No. 1231
The test results in Table 1 were obtained by the flame retardancy test method (surface test) of No. (flame retardant material).

Example 2 A new MMA was added to 100 parts of a 52% by weight surface-modified colloidal silica MMA solution prepared in the same manner as in Example
0 parts, MMA syrup 50 prepolymerized beforehand to a polymerization rate of 20%
After adding 0.5 part of AVN and dissolving 0.5 part of AVN, 300 parts of ATH was added and mixed with a stirrer to prepare a casting raw material. This casting raw material contains 10% by weight of silica solids and 60% by weight of ATH. Except for this, artificial marble was molded in the same manner as in Example 1.

Observation of the obtained ultrathin section of artificial marble with a transmission electron microscope confirmed that the colloidal silica was uniformly dispersed. This artificial marble has good transparency and depth, and has a beautiful surface appearance,
Furthermore, the oxygen index was 52, indicating excellent flame retardancy. Further, the test results in Table 1 were obtained by the flame retardancy test method (surface test) of the Ministry of Construction Notification No. 1231 (flame retardant material).

Example 3 17 parts of γ-methacryloyloxypropyltrimethoxysilane, isopropyl alcohol-dispersed colloidal silica (average particle diameter of about 15 n) was placed in a glass flask with stirring blades.
m, silica content 30% by weight, Catalyst Chemical Industry Co., Ltd., trade name OSCAL-1432) (240 parts), and add deionized water while stirring.
6.5 parts and 0.1 part of 36% by weight hydrochloric acid were added, and the temperature was raised to 70 ° C. After 2 hours, use a rotary evaporator at 40 ° C under reduced pressure
MMA is added at the same rate as the evaporation of the volatile component while distilling off the volatile component, and finally the dispersing medium is completely replaced with MMA.
Department. The obtained colloidal silica dispersion was transparent and hardly increased in viscosity because the surface-modified colloidal silica was substantially uniformly dispersed in MMA in the form of primary particles. The silica content calculated from the ash content after baking this dispersion in a crucible was 21% by weight.

After dissolving 0.16 parts of 2,2'-azobis (isobutyronitrile) in 100 parts of this dispersion, the ATH (average particle diameter 24 μm) was dissolved.
m, manufactured by Showa Denko K.K., trade name: Heidilight H-210) 1
50 parts were added and mixed with a stirrer to prepare a casting raw material.
In this casting material, silica solid content is 8% by weight, ATH
Is blended at 60% by weight.

The prepared casting material was pressure-reduced to remove dissolved air, and poured into a cell formed of a gasket and two stainless steel plates and set in advance to a thickness of 3 mm. Thereafter, polymerization was carried out at 80 ° C. for 2 hours and at 130 ° C. for 2 hours to form a target artificial marble.
The resulting artificial marble has good transparency and depth,
It exhibited excellent design with a beautiful surface appearance, and also exhibited an oxygen index of 48 and excellent flame retardancy.

Observation of an ultrathin section of the obtained artificial marble with a transmission electron microscope confirmed that the colloidal silica was uniformly dispersed as shown in FIG.

Example 4 150 parts of water-dispersed colloidal silica (average particle size: about 15 nm, silica content: 20% by weight, manufactured by Nissan Chemical Co., Ltd., trade name: Snowtex-O) was reduced with a rotary evaporator under reduced pressure.
At 0 ° C., isopropyl alcohol was added at the same rate as the evaporation of volatiles while distilling off the volatile components. Finally, the dispersion medium was completely replaced with isopropyl alcohol to make the total amount 100 parts. The obtained colloidal silica-dispersed isopropyl alcohol solution was a transparent colloid liquid whose viscosity hardly increased because the colloidal silica was substantially uniformly dispersed in isopropyl alcohol in the state of primary particles. The silica content calculated from the ash content after baking this dispersion in a crucible was 30% by weight.

An artificial marble was molded in the same manner as in Example 2 except that the thus obtained colloidal silica-dispersed isopropyl alcohol solution was used. The obtained artificial marble contains 10% by weight of silica solids and 60% by weight of ATH. As in Example 2, it has excellent transparency and depth, and has a beautiful surface appearance. And an oxygen index of 51, indicating excellent flame retardancy.

Example 5 In a glass flask, 200 parts of colloidal silica dispersed with isopropyl alcohol similar to that used in Example 1,
Add 20 parts of 2-hydroxyethyl methacrylate (hereinafter abbreviated as HEMA) and use a rotary evaporator under reduced pressure
MMA was added at the same rate as the evaporation of the volatile components while the volatile components were being distilled off at ℃, and finally the dispersion medium was completely replaced with a mixed solution of MMA and HEMA to make the total amount 120 parts. The obtained colloidal silica dispersion liquid was transparent and hardly increased in viscosity because the colloidal silica was substantially uniformly dispersed in the mixed solution of MMA and HEMA in the state of primary particles. The silica content calculated from the ash content after baking this dispersion in a crucible was 50% by weight.

An artificial marble was molded in the same manner as in Example 1 except that the thus obtained colloidal silica dispersion was used instead of the surface-modified colloidal silica-dispersed MMA solution. It showed good design with a good and beautiful surface appearance, and further showed an extremely excellent flame retardancy of 90 or more (above the measurable upper limit).

Comparative Example 1 In 40 parts of MMA, 40 parts of MMA syrup preliminarily polymerized to a polymerization rate of 20% and 0.2 part of AVN were dissolved, and then ATH (average particle diameter: 44 μm, manufactured by Nippon Light Metal Co., Ltd., trade name: BW- 33) 120 parts were added and mixed with a stirrer to prepare a casting raw material. The prepared casting material was molded and polymerized and cured in the same manner as in Example 1 to obtain an artificial marble. The resulting artificial marble has an ATH of 60
Although it was blended by weight, both the transparency and the depth were good, and excellent design with a beautiful surface appearance was exhibited. However, the oxygen index was as low as 31.
The test results shown in Table 1 were obtained by the flame retardancy test method (surface test) of Notification No. 1231 of the Ministry of Construction of Japan (flame retardant material).

Comparative Example 2 55 parts of MMA, 5 parts of MMA syrup preliminarily polymerized to a polymerization rate of 20%, 0.2 part of AVN, and 140 parts of ATH were used as comparative examples 1
The mixture was prepared in the same manner as described above, molded, polymerized and cured to obtain an artificial marble. Although the obtained artificial marble contained 70% by weight of ATH, both the transparency and the depth were good. But,
Its oxygen index was as low as 42. Further, the test results in Table 1 were obtained by the flame retardancy test method (surface test) of the Ministry of Construction Notification No. 1231 (flame retardant material).

Comparative Example 3 After dissolving 0.2 part of AVN in 75 parts of MMA, 25 parts of hydrophobic silica (average particle size: about 16 μm, manufactured by Nippon Aerosil Co., Ltd., trade name: R-972) was added, and mixed with a stirrer. A silica dispersion was obtained. The resulting dispersion was prepared by adding hydrophobic silica to MMA.
Due to agglomeration in the solution, the solution was opaque and the viscosity was significantly increased as compared with the colloidal silica dispersions of Examples 1 to 5.

To 100 parts of this dispersion solution, 150 parts of ATH (average particle diameter: 44 μm, manufactured by Nippon Light Metal Co., Ltd., trade name: BW-33) was added and mixed with a stirrer to prepare a casting raw material, but the viscosity was too high. Could not be injected into the cell.

Comparative Example 4 0.2 part of AVN, 150 parts of ATH (average particle size: 44 μm, manufactured by Nippon Light Metal Co., Ltd., trade name: BW-33), and 75 parts of glass fiber filler having a length of 3 mm were added to 75 parts of MMA. The mixture was mixed with a stirrer to prepare a casting raw material. This casting raw material contains 10% by weight of glass fiber and 60% by weight of ATH.

The prepared casting material was molded and polymerized and cured in the same manner as in Example 1 to obtain an artificial marble. The resulting artificial marble had a high oxygen index of 50, but the appearance was significantly reduced in transparency, impairing the excellent design characteristic of the artificial marble.

Comparative Example 5 After dissolving 0.2 part of AVN in 90 parts of MMA, 10 parts of hydrophobic silica (average particle diameter: 16 μm, manufactured by Nippon Aerosil Co., Ltd., trade name: R-972) was added, and mixed with a stirrer to disperse silica. A solution was obtained. The resulting dispersion was opaque because of the aggregation of the hydrophobic silica in the MMA, and had a significantly higher viscosity than the colloidal silica dispersions of Examples 1 to 5.

100 parts of this dispersion was added with 100 parts of ATH (average particle diameter: 44 μm, manufactured by Nippon Light Metal Co., Ltd., trade name: BW-33), and mixed with a stirrer to prepare a casting raw material. This casting raw material contains 5% by weight of silica and 50% by weight of ATH. Although the prepared casting raw material had a considerably high viscosity, it was molded and polymerized and cured in the same manner as in Example 1 to obtain an artificial marble. The obtained artificial marble had a low oxygen index of 35, and furthermore, the external appearance was significantly reduced in transparency, and the excellent design characteristic of the artificial marble was impaired. When the ultrathin section of this artificial marble was observed with a transmission electron microscope, it was confirmed that the hydrophobic silica remained aggregated and was not uniformly dispersed as shown in FIG.

Example 6 15 parts of trimethylmethoxysilane, 200 parts of isopropyl alcohol-dispersed colloidal silica similar to that used in Example 1, and 10 parts of a 0.1N hydrochloric acid aqueous solution were added to a glass flask with stirring blades, and the temperature was raised to 50 ° C. did. Two hours later, styrene was added at the same rate as that of the volatile components while removing volatile components at 40 ° C. under reduced pressure using a rotary evaporator. Finally, the dispersion medium was completely replaced with styrene to make the total amount 120 parts. . The obtained colloidal silica dispersion was transparent and hardly increased in viscosity because the surface-modified colloidal silica was substantially uniformly dispersed in styrene in the state of primary particles. The silica content calculated from the ash content after baking this dispersion in a crucible was 57% by weight.

To 100 parts of this dispersion, 30 parts of styrene were newly added, and an unsaturated polyester prepolymer (terephthalic acid-based unsaturated polyester, trade name: Yupica 6424, manufactured by Nippon Yupika Co., Ltd.) was added.
70 parts, benzoyl peroxide 2.5 parts, ATH (average particle size 44μ
m, 300 parts of Nippon Light Metal Co., Ltd., trade name BW-33) were added and mixed with a stirrer to prepare a casting material. This casting raw material contains 11% by weight of silica solids and 60% by weight of ATH.

The prepared casting raw material was molded in the same manner as in Example 1 to obtain a target artificial marble. However, the polymerization curing condition is 70
1.5 hours at 150C and 4 hours at 150C. The obtained artificial marble exhibited a design with a beautiful surface appearance unique to artificial marble, and exhibited an oxygen index of 50 and excellent flame retardancy.

Example 7 An artificial marble was molded in the same manner as in Example 2 except that magnesium hydroxide (average particle size: 20 μm, manufactured by Asahi Glass Co., Ltd., high-purity magnesium hydroxide) was used as the inorganic filler (B). The resulting artificial marble contains 10% by weight of silica solids and 60% by weight of magnesium hydroxide, but has good design properties, and has an excellent oxygen index of 57, exhibiting excellent flame retardancy. Was.

Example 8 A water-dispersed colloidal antimony pentoxide (average particle diameter 40 nm, antimony pentoxide content 50% by weight, Nissan Chemical Co., Ltd., trade name A-2550) as a colloidal metal oxide (C)
Was used to prepare a 30% by weight isopropanol dispersion, and an artificial marble was molded in the same manner as in Example 4 except that this was used.

The resulting artificial marble has an antimony pentoxide solid content of 10
Although it contains 60% by weight of ATH and 60% by weight of ATH, it shows good design properties and has an oxygen index of 56, exhibiting extremely excellent flame retardancy.

Example 9 As a colloidal metal oxide (C), water-dispersed colloidal alumina (average particle diameter 15 nm, alumina content 20% by weight,
An artificial marble was molded in the same manner as in Example 4 except that Nissan Chemical Co., Ltd., trade name alumina sol-520) was used.
The resulting artificial marble has an alumina solid content of 10% by weight, AT
Although H is blended at 60% by weight, it shows good design properties,
Furthermore, the oxygen index was 53, indicating excellent flame retardancy.

Example 10 Surface-modified colloidal silica obtained in the same manner as in Example 1
30 parts of a vinyl chloride-vinylidene chloride copolymer (Kureha Chemical Industry Co., Ltd., trade name Klehalon SPX105, vinyl chloride content: 76.6% by weight) were added to 100 parts of a 52% by weight dispersed MMA solution.
The artificial marble was molded in the same manner as in Example 1, except that 70 parts of MMA, 0.5 part of AVN and 300 parts of ATH were added. The obtained artificial marble has a silica solid content of 10% by weight and an ATH of 60%.
Although it was blended by weight, the transparency and the depth were good, the surface appearance was excellent, the design was excellent, and the oxygen index was 61, which was extremely excellent flame retardancy.

Example 11 An artificial marble was formed in the same manner as in Example 10, except that the MMA solution containing 52% by weight of the surface-modified colloidal antimony pentoxide obtained in the same manner as in Example 8 was used instead of the MMA solution containing colloidal silica. The resulting artificial marble contains 10% by weight of antimony pentoxide solids and 60% by weight of ATH, but shows good design properties and an oxygen index of
It showed excellent flame retardancy of 68.

Example 12 Surface-modified colloidal silica obtained in the same manner as in Example 1
30 parts of an acrylonitrile-styrene copolymer (manufactured by Daicel Chemical Industries, Ltd., trade name: Sebian N 020SF), 100 parts of 52% by weight dispersed MMA solution, 70 parts of MMA, 0.5 part of AVN,
An artificial marble was molded in the same manner as in Example 1 except that 300 parts of ATH was added. The resulting artificial marble contains 10% by weight of silica solids and 60% by weight of ATH, but exhibits excellent design with good transparency and depth, and has an extremely high oxygen index of 57. It showed flame retardancy.

Example 13 Surface-modified colloidal silica obtained in the same manner as in Example 1
5 parts of MMA syrup preliminarily polymerized to a polymerization rate of 20% and 70 parts of styrene were added to 100 parts of a 52% by weight dispersed MMA solution.
And 25 parts of 2-ethylhexyl methacrylate were added and mixed with a stirrer to prepare a 26% by weight dispersion of surface-modified colloidal silica. The solidified product of this dispersion had a refractive index at room temperature of 1.53.

60 parts of ATH and 0.1 part of AVN were added to 40 parts of the surface-modified colloidal silica 26% by weight dispersion thus obtained, and the mixture was mixed with a stirrer to prepare a casting raw material. This casting raw material contains 10% by weight of silica solids and 60% by weight of ATH.

The prepared casting raw material was molded in the same manner as in Example 1 to obtain a target artificial marble. The resulting artificial marble is
It exhibited a light yellow onyx-like transparency with very good design, and had an oxygen index of 53, which was good flame retardancy.

Example 14 Surface-modified colloidal silica obtained in the same manner as in Example 6
30 parts of trimethylolpropane trimethacrylate and 70 parts of polystyrene (trade name: Sbright T-2 beads, manufactured by Sumitomo Chemical Co., Ltd.) are added to 100 parts of a 57% by weight dispersed styrene solution, and mixed with a stirrer. A surface-modified colloidal silica 29% by weight dispersed viscous polymerizable syrup was prepared.
The refractive index of the solidified syrup at room temperature was 1.55.

ATH (average particle diameter 44 μm) was added to 40 parts of the thus obtained surface-modified colloidal silica 29 wt% dispersed syrup.
m, 60 parts of Nippon Light Metal Co., Ltd., trade name BW-33), t-
0.2 parts of butyl peroxyoctoate, 0.9 parts of zinc stearate, and 0.2 parts of γ-methacryloyloxypropyltrimethoxysilane are added to a double-armed kneader, and the mixture is stirred. A good high viscosity clay-like molding material was obtained. The molding material contains 12% by weight of silica solids and 60% by weight of ATH.

The prepared molding material was put into a plate-shaped mold (temperature: 120 ° C) set in a pressure molding machine and molded under pressure at a molding pressure of 60 kg / cm ² and a molding time of 5 minutes. Excellent,
An artificial marble with an onyx appearance without cracks or distortion was obtained, and its oxygen index was 53, indicating good flame retardancy.

Example 15 Surface-modified colloidal silica obtained in the same manner as in Example 1
66 parts of MMA syrup preliminarily polymerized to a polymerization rate of 10%, 34 parts of neopentyl glycol dimethacrylate, and 2,2′-azobis (4-methoxy-2, 4-dimethylvaleronitrile) to 0.0
045 parts, 0.45 part of di-t-butyl peroxide, 2,2-
0.15 parts of bis (t-butylperoxy) butane, di-t
-Butyl peroxy-hexahydroterephthalate
0.075 parts and 1.5 parts of formic acid were added to prepare a mixture. The polymer content in this mixture was 4.5% by weight (based on the resin content).

This mixed solution was poured into a cell assembled with two glass plates so as to have an interval of 10 mm, and was preliminarily polymerized at 50 ° C. for 3 hours to obtain a polymer content of 30.6% by weight (based on the resin content). A partially crosslinked gel polymer was obtained.

ATH (average particle size: 44 μm, manufactured by Nippon Light Metal Co., Ltd., trade name: BW-33) is added to 40 parts of the partially crosslinked gel polymer.
The mixture was mixed and kneaded at room temperature for 30 minutes using a pressure type kneader to obtain an inorganic material-filled molding material. In this molding material,
It contains 10% by weight of silica solids and 60% by weight of ATH.

The prepared molding material is placed in a plate mold at a mold temperature of 130 ° C.
After pressurizing at an initial pressure of 20 kg / cm ² for 0.5 minutes, increasing the pressure to 150 kg / cm ² and performing pressure molding for 14.5 minutes, the colorless and deep feeling without coloring such as yellow is good and beautiful. An artificial marble with a surface appearance was obtained, and its oxygen index was 53.
And high flame retardancy.

Example 16 Surface-modified colloidal silica obtained in the same manner as in Example 1
For 100 parts of a 52% by weight dispersed MMA solution, 50 parts of MMA, 25 parts of MMA syrup preliminarily polymerized to a polymerization rate of 20%, halogen-containing condensed phosphoric acid ester (manufactured by Daihachi Chemical Industry Co., Ltd.
An artificial marble was molded in the same manner as in Example 1 except that 25 parts of trade name CR509, phosphorus content of 13.5% by weight or more, halogen content of 24.0% by weight or more) were added in 25 parts, AVN in 0.5 parts and ATH in 300 parts. The resulting artificial marble, which contains 10% by weight of silica solids and 60% by weight of ATH, exhibited good design properties, and exhibited an extremely excellent flame retardancy of 60 as its oxygen index. .

Example 17 A fine yellow pigment (about 82.5%) was added to 50 parts of a soybean oil epoxide resin.
An iron oxide pigment dispersion 0.01 prepared by mixing and stirring 40 parts by weight of a ferric hydroxide pigment having a Fe ₂ O ₃ content of 10% by weight and 10 parts of a black iron oxide pigment (containing 98% by weight of Fe ₃ O ₄ ). Was added to 100 parts of the casting raw material obtained in the same manner as in Example 2, and this was used as a casting raw material to mold an artificial marble in the same manner as in Example 2. The resulting artificial marble contains 10% by weight of silica solids and 60% by weight of ATH, but has a good appearance of translucent and uniform thin almond color, and has an excellent oxygen index of 51. It showed flame retardancy.

Example 18 100 parts of the casting material obtained in the same manner as in Example 1 were dyed with a yellow nylon floc having a length of 1.3 mm and a fineness of 2 denier (yellow dyeing solution having a dye concentration of 3% by weight). ) Was added, and this was used as a casting raw material to mold an artificial marble in the same manner as in Example 2. The resulting artificial marble has a silica solid content of 10% by weight,
Although it contained 60% by weight of ATH, it had a translucent and uniform yellow appearance, and had an excellent oxygen index of 52, indicating excellent flame retardancy.

Example 19 To 100 parts of a casting raw material obtained in the same manner as in Example 2, 1 part of activated carbon (apparent specific gravity 0.4) of 350 μm ON with a 500 μm JIS standard sieve was added, and this was used as a casting raw material. In the same manner as in 2, an artificial marble was molded.
The resulting artificial marble has a silica solid content of 10% by weight, ATH
Was contained in an amount of 60% by weight, but had a good appearance resembling a granite having a uniform black spot pattern, and exhibited an oxygen index of 53 and excellent flame retardancy.

Example 20 Surface-modified colloidal silica obtained in the same manner as in Example 1
50 parts of MMA syrup preliminarily polymerized to a polymerization rate of 20%, 0.5 part of AVN, ATH
250 parts of a mixture [opaque calcined talc (based on the weight of the mixture, an optical density of 2.0 or more with respect to visible light, an average particle size of 5
80 μm) 45% by weight, opaque magnetite (optical density for visible light of 2.0 or more, average particle size of 580 μm), and translucent wollastonite (optical density for visible light of 1.2 ± 0.1, average particle size of 340 μm) An artificial marble was obtained in the same manner as in Example 1 except that 100 parts of a mixture consisting of 35% by weight was added. The resulting artificial marble contains 10% by weight of silica solids, 50% by weight of ATH, and 20% by weight of other inorganic substances, but its appearance resembles natural granite and its oxygen The index was 56, showing excellent flame retardancy.

Example 21 ATH (average particle diameter: 44 μm, manufactured by Nippon Light Metal Co., Ltd., trade name: BW-33) was added to 40 parts of an unsaturated polyester resin prepolymer (trade name: Polymer 3308PS, manufactured by Takeda Pharmaceutical Co., Ltd.)
60 parts and 0.5 parts of methyl ethyl ketone peroxide were added, and after stirring, the mixture was poured into a mold and cured at room temperature to obtain a substantially transparent plate-like cured product. The parallel light transmittance of this cured plate was measured by a measuring method A using a sheet having a thickness of 2 mm in accordance with JIS K-7105 and found to be 12.3%. The cured product was pulverized to a particle size of 0.5 to 3 mm to obtain substantially transparent particles.

Next, 100 parts of a 52% by weight dispersed MMA solution of the surface-modified colloidal silica obtained in the same manner as in Example 1 was newly added to MMA.
50 parts, substantially transparent particles 50 parts, AVN 0.5 parts, ATH
, And artificial marble was molded in the same manner as in Example 1 except that 300 parts were added. The resulting artificial marble has a silica solid content of
Although it contains 10% by weight and ATH at 66% by weight, it has an appearance close to that of natural stone, and its oxygen index is 65, showing extremely excellent flame retardancy.

Example 22 Surface-modified colloidal silica obtained in the same manner as in Example 1
10 parts of MMA syrup preliminarily polymerized to a polymerization rate of 20% and 70 parts of styrene were added to 100 parts of a 52% by weight dispersed MMA solution.
And 20 parts by weight of cyclohexyl methacrylate, and mixed with a stirrer to prepare a 26% by weight dispersion of surface-modified colloidal silica. The refractive index of the solidified product of this dispersion at room temperature is
It was 1.53.

60 parts of ATH and 0.1 part of AVN were added to 40 parts of the surface-modified colloidal silica 26% by weight dispersion thus obtained, and the mixture was mixed with a stirrer to prepare a casting raw material. This casting raw material contains 10% by weight of silica solids and 60% by weight of ATH.

The prepared casting raw material was molded in the same manner as in Example 1 to obtain a target artificial marble. The resulting artificial marble is
It exhibited very good design with a light yellow onyx-like transparency, and had an excellent oxygen index of 53, indicating good flame retardancy.

As described in detail above, in the present invention, the average particle diameter is 1
By dispersing a colloidal metal oxide of ~ 100nm in polymer stably and substantially in the form of primary particles without agglomeration, it can be easily mixed with polymer without increasing the viscosity of the system Can be highly filled with the metal oxide.
The resulting artificial marble is highly filled with the metal oxide at a high level without deteriorating the excellent design properties (transparency, concealing property, surface appearance) unique to the artificial marble while maintaining the transparency. Can be given a high degree of noncombustibility.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI // C04B 111: 54 (72) Inventor Shogo Okazaki 20-1 Miyukicho, Otake City, Hiroshima Prefecture Mitsubishi Rayon Co., Ltd. 56) References JP-A-52-39737 (JP, A) JP-A-3-285854 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C04B 26/04, 14/02 , 14/04 C04B 14 / 36,16 / 06,20 / 02 C08F 20/10 C08K 3 / 22,3 / 36 C08L 101/00

Claims (18)

(57) [Claims] 1. A polymer (A) of a radically polymerizable vinyl compound (a), an inorganic filler (B) having an average particle diameter of 1 μm or more, and a colloidal metal oxide (C) having an average particle diameter of 1 to 100 nm. An artificial marble, wherein the metal oxide (C) is substantially uniformly dispersed in the polymer (A) in a state of primary particles. 2. The polymer (A) contains at least 50% by weight of a polymer of at least one compound selected from methacrylates, based on the total weight of the polymer (A). The artificial marble according to claim 1, wherein the artificial marble is characterized in that: 3. A polymer (A) comprising, as main components, 5 to 40% by weight of a vinyl chloride-vinylidene chloride copolymer and 95 to 60% by weight of methyl methacrylate based on the total weight of the polymer (A). The artificial marble according to claim 1, comprising a polymer represented by the following formula: 4. The polymer (A) comprises 5 to 40% by weight, based on the total weight of the polymer (A), of an acrylonitrile-styrene copolymer and 95 to 60% by weight of methyl methacrylate. 2. The artificial marble according to claim 1, comprising a polymer. 5. The polymer (A) is a copolymer comprising two or more monomers selected from the group consisting of cyclohexyl methacrylate, methyl methacrylate, 2-ethylhexyl methacrylate and styrene, and having a refractive index of room temperature. 2. The artificial marble according to claim 1, wherein the ratio is 1.51 to 1.55. 6. A monomer mixture wherein the polymer (A) comprises i) 30 to 80% by weight of an aliphatic polyfunctional methacrylate and 70 to 20% by weight of an aromatic compound having an ethylenically unsaturated bond in a molecule. 65-45% by weight, and ii) a mixture of 35-55% by weight of an aromatic compound-based polymer having an ethylenically unsaturated bond in the molecule, which has a refractive index of 1.55% at room temperature. 2. The artificial marble according to claim 1, wherein the range is from 1.5 to 1.57. 7. The artificial marble according to claim 1, wherein the colloidal metal oxide (C) is at least one selected from the group consisting of colloidal silica, colloidal antimony oxide, and colloidal alumina. 8. A polymer (A) of 15 to 50% by weight, an inorganic filler (B) of 45 to 75% by weight, a colloidal metal oxide of 5 to 30% by weight, based on the total weight of the artificial marble. Object (C)
The artificial marble according to claim 1, comprising: 9. The total of the inorganic filler (B) and the metal oxide (C) is 50 to 85% by weight based on the total weight of the artificial marble.
Wherein the weight ratio of (B) / (C) is 1.5 to 15, and at least one polymer (A) selected from methacrylic esters based on the total weight of the polymer (A) 9. The artificial marble according to claim 8, which contains at least 50% by weight of a polymerized product of the above. 10. The artificial marble according to claim 1, wherein the oxygen index measured by the method described in JIS K7201 is 45 or more. 11. The composition according to claim 1, further comprising at least one flame retardant (D) selected from the group consisting of chlorine flame retardants, bromine flame retardants, phosphorus flame retardants, and inorganic flame retardants. An artificial marble according to range 1. 12. The method according to claim 1, further comprising an iron oxide pigment (E) having an average particle diameter of 10 μm or less.
The artificial marble described. 13. The artificial marble according to claim 1, further comprising a colored short fiber (F) having a length of 0.2 to 13 mm and a fineness of 1 to 300 denier. 14. The artificial marble according to claim 1, further comprising carbon particles (G). 15. An opaque particle (H) having a minimum dimension of 200 μm or more and an optical density of 2.0 or more for visible light, and an opaque particle (H) having a minimum dimension of 200 μm or more and an optical density of 2.0 or less for visible light. The artificial marble according to claim 1, further comprising at least one kind (I) selected from translucent particles and transparent particles. 16. A resin composition comprising 15 to 60% by weight and an inorganic filler 85.
2. Artificial marble according to claim 1, further comprising substantially transparent particles (J) having a particle size of 0.2 to 5 mm, consisting of .about.40% by weight. 17. A dispersion comprising a colloidal metal oxide (C) having an average particle diameter of 1 to 100 nm and a dispersion medium, and at least one silane compound (K) represented by the following general formula (i): Is hydrolyzed and polycondensed to modify the surface of the colloidal metal oxide (C), and then the dispersion medium is replaced with a radically polymerizable vinyl compound (a), and the inorganic filler (B) is further substituted. A method for producing artificial marble, comprising polymerizing and curing a radically polymerizable vinyl compound (a) after the addition. SiR ¹ _a R ² _b (OR ³ ) _c (i) (In the general formula (i), R ¹ and R ² are an ether bond, an ester bond, an amino group, a mercapto group, a halogen atom or a carbon atom.
A hydrocarbon group having 1 to 10 carbon atoms which may have a carbon double bond, R ³ is a hydrogen atom or an ether bond, an ester bond or a carbon atom having 1 to 5 carbon atoms which may have a carbon-carbon double bond. Ten
A and b are each an integer of 0 to 3, c is 4-ab, and represents an integer of 1 to 4. ) 18. A radical polymerizable vinyl having at least one hydroxy group in a molecule of a dispersion medium in a dispersion comprising a colloidal metal oxide (C) having an average particle diameter of 1 to 100 nm and a dispersion medium. After replacing with a radical polymerizable vinyl compound (a) containing at least one compound selected from the group consisting of a compound and a radical polymerizable vinyl compound having at least one epoxy group capable of generating a hydroxy group in a molecule, an inorganic filler A method for producing artificial marble, comprising adding (B) and polymerizing and curing the radically polymerizable vinyl compound (a).