JPH03257048A - Artificial marble excellent in impact resistance and cutting workability - Google Patents

Abstract

PURPOSE:To obtain artificial marble which is excellent in impact resistance, cutting workability and transparency and beautiful by dispersing hydrate of metallic oxide into the mixture of specified urethane (meth)acrylate and a specified radical polymerizable monomer and thereafter molding and curing this mixture. CONSTITUTION:Artificial marble is obtained by dispersing 100-800 pts.wt. hydrate (II) of metallic oxide for resin component (I) which consists of a mixture of 2-30 pts.wt. urethane (meth)acrylate (A) having 2,500-30,000 number average mol.wt. and 7,000-40,000 weight average mol.wt. shown in a formula and a radical polymerizable monomer (B) described hereunder and incorporates 100 pts.wt. total of (A) and (B) and thereafter molding and curing this dispersed mixture. The radical polymerizable monomer (B) is constituted of 3-40 pts.wt. aliphatic multifunctional (meth)acrylate, 30-95 pts.wt. monofunctional aromatic vinyl compd. and 0-65 pts.wt. monofunctional alkyl (meth)acrylate.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an artificial marble useful as a building material that has excellent impact resistance and excellent machinability.

[Conventional technology]

Artificial marble using hydrated metal oxides as a filler is conventionally known. For example, methyl methacrylate artificial marble is made by kneading aluminum hydroxide into methyl methacrylate silt and hardening it using an organic peroxide as a curing agent, or unsaturated polyester resin or epoxy (meth)acrylate is used instead of methyl methacrylate sill. A method using a vinyl ester resin dissolved in is known. These sills and resins are injected into molds of various shapes or between moving belts, and then heated to room temperature or a temperature of around 60° C. to be molded.

On the other hand, products that are molded under heat and pressure using a mold are also known, for example, a mixture of unsaturated polyester resin, epoxy (meth)acrylate resin, and metal oxide hydrate with glass fiber or thickened material. There are premix molding materials that give astronomical stone-like articles by adding agents.

[Problems to be Solved by the Invention] However, the artificial marble cast using the above-mentioned silica etc. has a high viscosity (due to the high viscosity of the composition, it is difficult to determine the amount and size of the filler that can be used). For example, when using a large amount of filler to make artificial marble with a high filler content that has excellent heat resistance and flame retardancy, it is difficult to disperse the filler and a beautiful product cannot be obtained. In order to suppress the increase in viscosity caused by high filling, methods such as blending particles with a large particle size within a range that does not cause sedimentation are taken. Due to the use of large fillers, cracks and pinholes occur on the surface, resulting in poor impact resistance.In addition, hot water penetrates through pinholes, causing "blisters", making water resistance difficult. There were also sexual flaws.

On the other hand, methyl methacrylate resin and unsaturated polyester resin, which have been used as pace resin for artificial marble,
Vinyl ester resins do not inherently have excellent impact resistance, and artificial marble obtained by heating and pressure molding a premix molding material using these resins as a base resin has improved strength due to glass fibers. Even if it does, it is not sufficient, glass fiber patterns tend to appear, and there are also problems with heat resistance. Furthermore, methyl methacrylate-based artificial marble had poor solvent resistance and transparency, and unsaturated polyester-based artificial marble had poor weather resistance.

In order to improve these drawbacks, the present inventors have already proposed an artificial marble based on a monomer cured product consisting of an aliphatic polyfunctional (meth)acrylate and an aromatic vinyl compound (Japanese Unexamined Patent Publication No. 128956/1989). issue). However, this monomer cured product-based artificial marble cannot be said to have sufficient handling properties during cutting, compared to methyl methacrylate resin-based artificial marble.
Artificial astronomical stone has the disadvantage of high cutting resistance (and easy chipping of the cut cross section). Artificial astronomical stone is used for kitchen tops, table tops, wall materials, etc. It is often used as a thick plate by stacking several plates and gluing them together (If there are chips in the cut section, especially at the corners, the joints will be noticeable and will seriously spoil the appearance, making it impossible to create a beautiful integrated marble. In order to obtain a chip-free cut surface, it was necessary to reduce the machining speed and update the tool more frequently. Methyl methacrylate-based artificial marble is also better than the aforementioned artificial marble, but this The present invention aims to improve the current state of the art by creating an unsaturated polyurethane material that has excellent impact resistance and machinability, and has a highly transparent and elegant appearance. The present invention provides artificial marble having the following characteristics.

[Means and effects for solving the problem] As a result of various studies by the present inventors, the artificial marble obtained by dispersing a specific amount of a specific filler into a specific resin composite acid and then molding and hardening it. The present invention was completed by discovering that the object was well achieved.

That is, the present invention is based on the general formula (where R1 is hydrogen or a methyl group, and Rt has 2 carbon atoms)
-4 glycol residue, X is a residue of polyether polyisocyanate, polyester polyisocyanate, or polyisocyanate of an elastomer having a hydroxyl group at the terminal group, and n is a positive number of 2 to 3. ), and the number average molecular weight measured by GPC method is 2.
, 500 to 30,000 and a weight average molecular weight of 7,000 to 40,000, 2 to 30 parts by weight of urethane (meth)acrylate (A), and 3 to 40 parts by weight of aliphatic polyfunctional (meth)acrylate. and a polymerizable monomer (B) consisting of 30 to 95 parts by weight of a monofunctional aromatic vinyl compound and 0 to 65 parts by weight of a monofunctional alkyl (meth)acrylate, the sum of (A) and (B). Impact resistance and cutting workability obtained by dispersing 100 to 800 parts by weight of the metal oxide hydrate (II) in the resin composition (I), which is 100 parts by weight, and then molding and hardening. This article concerns artificial marble that has excellent properties.

When carrying out the present invention, if the resin composition (I) and the metal oxide hydrate (n) are mixed using a mixer capable of high-speed stirring such as a disper or a homo mixer, it is possible to temporarily shake the resin composition (I) and the metal oxide hydrate during mixing. Although denaturation occurs and fluidity is almost lost, ultimately, even if a large amount of 300 parts by weight or more of the metal oxide hydrate is added to 100 parts by weight of the resin composition, casting will not be possible. A suitable low viscosity formulation of 10-100 voids is obtained.

In addition, if mixed using a low-speed mixer such as a kneader, as the metal oxide hydrate is added, it will become a sticky lump like bread, and while maintaining its shape, the metal oxide will eventually be mixed. Even if a large amount of oxide hydrate is added, up to about 800 parts by weight, it can be mixed, and a dough-like molding material with excellent fluidity when pressurized can be obtained.

The thus obtained low viscosity compound or fresh bread-like molding material can be easily cast or molded under heat and pressure.
With a filler amount of about 0 to 400 parts by weight, beautiful translucent, milky-white artificial marble can be obtained, and with a high filler amount of 400 to 800 parts by weight, highly flame-retardant milky white artificial marble can be obtained. can get. In addition, this artificial marble product has excellent impact resistance against falling objects, colliding objects, etc., and has excellent workability as it can be easily cut and polished with ordinary woodworking tools.

Urethane (meth)acrylate (A
) are polyethers, polyesters, and elastomers having a urethane bond in the main chain and a (meth)acryloyl group at the terminal, as represented by the general formula above, and the urethane (meth)acrylate (A) is It can be obtained by reacting a polyether polyol, polyester polyol or elastomer having a hydroxyl group at the end of the molecule with a polyfunctional incyanate compound and a hydroxyalkyl (meth)acrylate.

Examples of the polyether polyol used to obtain the urethane (meth)acrylate (A) include polyethylene glycol, polypropylene glycol, triol of glycerin-based polypropylene glycol, polytetramethylene glycol, polyhexamethylene glycol, etc. Examples of polyols include polybasic acids such as phthalic acid, isophthalic acid, maleic acid, adipic acid, and trimellitic acid, ethylene glycol, propylene glycol, 1,4-butanediol,
Condensation reaction products with polyhydric alcohols such as 1.6-hexanediol and trimethylolpropane, ring-opening polymers such as ε-caprolactone, and elastomers such as hydroxyl group-terminated polyisoprene, polybutadiene, etc. Copolymers containing polydienes and copolymerizable monomers can be mentioned.

Examples of polyfunctional isocyanate compounds include tolylene diisocyanate, diphenylmethane diisocyanate, tetramethylene glycol diisocyanate),
．． Examples include 4-cyclohexyl diisocyanate, isophorone diisocyanate, triphenylmethane triisocyanate, dimethyltriphenylmethane triisocyanate, among others, polyether polyisocyanate obtained by reacting polyether and isophorone diisocyanate. It is desirable to use urethane (meth)acrylate (A) obtained using urethane (meth)acrylate (A) because it provides artificial marble with excellent weather resistance and less change in surface color over time. Further, since urethane acrylate with a narrow molecular weight distribution can be easily obtained, it is desirable to obtain artificial marble which has a low viscosity as a molding material, is easy to handle, and has excellent impact strength and machinability.

Further, examples of the hydroxyalkyl (meth)acrylate include hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, and the like.

An example of a method for synthesizing urethane (meth)acrylate (A) is to apply NC to polypropylene glycol dehydrated under reduced pressure.
Infron diisocyanate is added so that the O:OH molar ratio is about 2:1, and a reaction is caused using triethylamine or the like as a catalyst to obtain NCO-terminated polypropylene glycol. Furthermore, it can be obtained by adding hydroxyethyl acrylate to the NCO group at the end of the polymer so that the molar ratio of NCO:OH is approximately 1=1, and reacting with dibutyltin dilaurate or the like as a catalyst.

The number average molecular weight (Mn) of the urethane (meth)acrylate used in the present invention is 2,500 to 30°000, and the weight average molecular weight (Mw) is 7.000 to 40,000.
0 range, and urethane (meth)acrylate (
A) The number of (meth)acryloyl groups per molecule is 2 to
The range is 3.

Preferably Mn is 3,000 to 15,000, and Mn
w is s, ooo to 35,000, more preferably i is s, ooo to 12,000, and the i/double ratio (D value) is 2 or less. Mn is less than 2,500 or i is 7,0
If the cured product is less than 0.00 and the obtained cured product is greater than 40,000, the viscosity of the urethane (meth)acrylate is high and handling is poor (bubbles remain in the obtained cured product, making it unsuitable in terms of appearance and strength). Become.

As shown in Example 4, even if r and Mw are within the range of the present invention application, a cured product with a large D value has a lower heat distortion temperature than a cured product with a small D value. Urethane (meth)acrylate with a D value of less than 2 satisfies the three properties of machinability, impact resistance, and heat resistance in the best balance,
It is possible to obtain artificial marble with minute chipping on the cut surface, high impact strength, and sufficiently high thermal deformation temperature for practical use.

The radically polymerizable monomer (B) used in the present invention includes 3 to 40 parts by weight of aliphatic polyfunctional (meth)acrylate, 30 to 95 parts by weight of monofunctional aromatic vinyl compound, and 0 parts by weight of monofunctional alkyl (meth)acrylate. ~65 parts by weight are essential components. If the aliphatic polyfunctional (meth)acrylate component is less than 3 parts by weight, the heat resistance of the resulting artificial marble will be lowered, and the reactivity of the resin composition will be lowered, resulting in a longer time required for curing, which is undesirable. If it exceeds 40 parts by weight, it becomes hard (brittle) and has poor machinability.

If the amount of the monofunctional aromatic vinyl compound component is less than 30 parts by weight, the refractive index of the resin component will be low, making it impossible to obtain a transparent astronomical stone-like appearance.

Monofunctional alkyl (meth)acrylates have excellent copolymerizability with aromatic vinyl compounds, have the effect of facilitating the copolymerization reaction, making it easier to control the curing reaction, and providing weather resistance to the resulting cured product. Therefore, it is preferably used, but if it exceeds 65 parts by weight, transparency decreases.

The aliphatic polyfunctional (meth)acrylates used in the present invention include ethylene glycol di(meth)acrylate, brobylene glycol di(meth)acrylate, butylene glycol di(meth)acrylate, and neopentyl glycol di(meth)acrylate. , glycerin tri(meth)acrylate, trimethylolpropane tri(meth)
Acrylate, dipentaerythritol hexa(meth)
Contains acrylate, etc.

Examples of aromatic vinyl compounds include styrene, α-methylstyrene, p-methylstyrene, and divinylbenzene.

Examples of alkyl (meth)acrylates include methacrylic acid esters such as methyl methacrylate, ethyl methacrylate, t-butyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, methyl acrylate, ethyl acrylate, n-butyl acrylate, acrylic acid 2
-There are acrylic acid esters such as ethylhexyl.

In addition to the above essential components, other monomers and oligomers such as (meth)acrylic acid, salts thereof, unsaturated polyester oligomers, fumaric acid esters, and maleimides are used as part of the monomer mixture. You can also do that. However, if these other monomers or oligomers are used too much, it may be difficult to obtain a product with a high filler content, or the product may have poor heat resistance and hot water resistance. Furthermore, if the other monomers used have low boiling points, they may foam during molding and the product may become opaque. Furthermore, in order to reduce shrinkage during mold curing, prevent cracks and improve surface smoothness of the product,
A thermoplastic polymer may be blended into the monomer mixture. Examples of thermoplastic polymers include (meth)acrylic polymers such as polymethyl methacrylate, (meth)acrylate-styrene copolymers, polystyrene, polyvinyl acetate, styrene-vinyl acetate copolymers, polyvinyl chloride, polybutadiene, polyethylene, Conventionally known low shrinkage polymers such as polycaprolactam and saturated polyester can be used alone or in combination. When thermoplastic polymers for low shrinkage are blended in large amounts, the viscosity of the monomer body temperature liquid increases, making it difficult to obtain a casting compound with a high filler content, and reducing the transparency and heat resistance of the product. You may end up getting something inferior. Therefore, it is preferable to use the thermoplastic polymer for low shrinkage in as small a quantity as possible, and 20 parts by weight per 100 parts by weight of the total amount of the urethane (meth)acrylate (A) and the radically polymerizable monomer (B).
It is desirable to use it in an amount of 0 parts by weight or less, more preferably 150 parts by weight or less. Further, in order to use the present resin composition in hot pressure molding, a viscosity-enhancing polymer may be used for the purpose of increasing the viscosity during molding and further improving handling workability for press molding. Examples of this thickening polymer include methacrylate polymers obtained by copolymerizing 1 to 2% by weight of (meth)acrylic acid to methyl methacrylate, and maleated inbrene rubber, which have two or more carboxyl groups in their side chains or terminals. Thermoplastic polymers having two or more hydroxyl groups in one molecule, such as methacrylate polymers obtained by copolymerizing methyl methacrylate with 1 to 2% by weight of hydroxyethyl methacrylate, and polypropylene glycol. be. As thickeners for these two types of thickening polymers, metal oxides and hydroxides such as magnesium oxide and magnesium hydroxide are used for the former, and polyesters such as tolylene diisocyanate and isophorone diisocyanate are used for the latter. Functional incyanates are used.

The amount of metal oxide hydrate (I[) to be used is determined by the amount of metal oxide hydrate (I[)
I) The proportion ranges from 100 to 800 parts by weight per 100 parts by weight. If the amount used is less than 100 parts by weight, flame-retardant artificial marble with excellent heat resistance cannot be obtained;
If the amount exceeds 0 parts by weight, it becomes difficult to disperse into the resin composition (I) or the fluidity during molding and curing is impaired, making it impossible to obtain a translucent and uniform artificial marble.

Hydrates of metal oxides used in the present invention include, for example, aluminum hydroxide, magnesium hydroxide, and calcium hydroxide. Among these, when using metal oxide hydrates with an average particle size of 5 microns or less as measured by the air permeation method, a beautiful product with a particularly good surface condition can be obtained, and it will also have particularly excellent hot water resistance. preferable.

The artificial marble containing 3 to 10 parts by weight of an aliphatic polyfunctional (meth)acrylate component in the resin composition (I) and using aluminum hydroxide has a heat distortion temperature of 100°C or higher, and is heat resistant and hot water resistant. , excellent weather resistance, flame retardancy, and high light transmittance (transparent to translucent milky white beautiful artificial marble can be obtained.
When containing 40 parts by weight and using magnesium hydroxide,
Artificial marble with particularly high heat resistance can be obtained.

In addition, as long as it does not adversely affect the flame retardancy of products from which inorganic fillers such as silica, alumina, quartz, calcium silicate, calcium carbonate, talc, and clay can be obtained, some of the hydrates of the metal oxides may be used. It can be used in place of the part.

Using a silane coupling agent when dispersing the resin composition (I) and the metal oxide hydrate (n) improves the water resistance of the product obtained by molding and curing, which is preferable. Examples of the agent include γ-methacryloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, vinyltriethoxysilane, and vinyltriacetoxysilane.

Examples of curing agents used in molding and curing include benzoyl peroxide, cyclohexanone peroxide, methyl ethyl ketone peroxide, bis(4-
t-butylcyclohexyl) peroxydicarbonate, t-butylperoxybenzoate, t-butylperoxacyoctoate, etc. are used. Among these, particularly preferred for press molding are medium- and high-temperature curing agents such as t-butyl peroxyoctoate and benzoyl peroxide, which give cured products with good transparency without causing cracks. In addition, medium- and low-temperature curing agents are used alone or together with organic amines and polyvalent metal salts as accelerators.
Particularly preferred for casting is bis(4-t-butylcyclohexyl) peroxydicarbonate (Barriki Dox PX-16, manufactured by Nippon Kayaku ■).

To carry out the present invention specifically, first, for example, 2 to 30 parts by weight, preferably 5 to 20 parts by weight of urethane (meth)acrylate (A), and a radically polymerizable monomer (B)
A resin composition (I) containing 70 to 98 parts by weight, preferably 80 to 95 parts is prepared, and 100 parts by weight of this resin composition (I) is prepared.
Metal oxide hydrate (II) 100-8 parts by weight
00 parts by weight are dispersed.

At this time, the metal oxide hydrate (II) may be treated with a silane coupling agent in advance, or the metal oxide hydrate (II) may be 0.1
It is also possible to use the metal oxide hydrate (n) after dissolving or branching a silane coupling agent corresponding to ~2.0% in the resin composition (I).

In addition, the metal oxide hydrate (
In addition to II), if necessary, various fillers, reinforcing fibers such as glass fibers, mold release agents such as zinc stearate, thixotropic agents, plasticizers, flame retardants and flame retardants in amounts that do not impede the effects of the present invention. A curing agent, a coloring agent, etc. may be added, and the curing agent is usually added in an amount corresponding to 0.5 to 3.0% based on the weight of the resin composition (I).

As for the dispersion method, a high-speed stirrer, a pigment dispersion machine for paint production, or a mixed wire roll can be used to prepare a low-viscosity compound for casting, and a raw bread-like molding material for press molding can be used. To achieve this, a low-speed, powerful mixer such as a kneader is suitable.

The low-viscosity compound or molding material thus obtained is injected, press-fitted, or put into a mold, and molded and hardened by various molding methods such as casting, pressing, injection, extrusion, and transfer. In the case of cast molding, preliminary curing is performed at a temperature of, for example, about 60°C, and if necessary, post-curing is performed by heating at 80 to 120°C to obtain a product. In the case of heat/pressure molding using a press or the like, the product can be cured at a mold temperature of, for example, 80 to 180°C.

〔Effect of the invention〕

The artificial marble of the present invention is an article with excellent impact resistance and moderate toughness, and is easy to cut using cutting equipment for woodworking. - It has a beautiful transparent and semi-transparent milky white appearance.

Therefore, the artificial marble of the present invention can be freely processed and used for building materials such as bathtubs and kitchen counters.

(Examples) Examples will be described in more detail below, but these do not represent the entirety of the present invention.

Reference Example 1 100 parts by weight of P-400 manufactured by Asahi Denka Kogyo ■, which is a bifunctional polypropylene glycol (hereinafter abbreviated as PPG) with an average molecular weight of 400, was charged into four rosetteable flasks, and 9
Dehydrate at 0°C and 10 Torr for 2 hours. This was cooled to 60°C, 74.1 parts by weight of isophorone diisocyanate and 0.033 parts by weight of dibutyltin dilaurate were added, and the mixture was reacted at 60°C for 18 hours. The obtained NCO terminal P
19.3 parts by weight of hydroxyethyl acrylate was added to PG and further reacted at 60°C for 18 hours, number average molecular weight 3,000, weight average molecular weight 7.200, D = 2.4.
A viscous liquid urethane acrylate (1) having two acryloyl groups was obtained.

Reference Examples 2 to 7 According to the same procedure as Reference Example 1, urethane (meth)acrylates (2) to (7) were obtained with the compositions shown in Table 1.

Table 1 * Composition units are parts by weight (Note 1) P-400: Polypropylene glycol (Note 2) manufactured by Kadenka Kogyo ■
Placcel-220: manufactured by Daicel Chemical Industry ■, poly-ε caprolactone (Note 3) TL-6000: manufactured by Sanyo Chemical Industry ■, trimethylolbroban-based polybrobylene glycol (Note 4) GP-5000: manufactured by Sanyo Chemical Industry ■, glycerin Base polypropylene glycol (Note 5) Isophorone diisocyanate: Manufactured by West German Hils, non-yellowing diisocyanate (Note 6) Coronate 209
4 Manufactured by Nippon Polyurethane Industry ■, hexamethylene dicysocyanate Example 1 30 parts by weight of urethane acrylate (1) obtained in Reference Example 1, 52 parts by weight of styrene, 13 parts by weight of methyl methacrylate
parts by weight, 5 parts by weight of ethylene glycol dimethacrylate, and 1.5 parts by weight of a silane coupling agent (KBM-503, manufactured by Shin-Etsu Chemical Co., Ltd.) were mixed to obtain a resin composition.

Next, 200 parts by weight of aluminum hydroxide (Hisilite H-320', average particle size 3.5 microns, manufactured by Showa Denko ■) was kneaded into this resin composition using a high-speed stirrer, and then the curing agent Kayaester 0(t-butylperoxy-2
-0.8 parts by weight of ethylhexanoate (manufactured by Kayaku Nuri ■) was added, and after mixing, defoaming was carried out under reduced pressure to obtain a blend. The viscosity of this formulation was 7.5 poise at a liquid temperature of 30°C.

This formulation was poured into a 11000 x 600 x 6so casting mold and cured at 60°C, cured in 30 minutes, and then post-cured at 120°C for 2 hours.

The obtained cured product was milky white and had an astronomical stone appearance that scattered light beautifully, and as shown in Table 2, it was a product that was flame retardant and had excellent impact resistance and machinability. Ta.

Examples 2 to 5 Cured products were obtained by carrying out the same operation as in Example 1, except that the composition was as shown in Table 2.

This cured product scattered a beautiful milky white light, had flame retardancy, and as shown in Table 2, was an article with excellent impact resistance and cutting workability.

Table 2 (Note-1) Kaya ester O; t-butyl peroxy-2-ethyl hesanoate,
Kaya Ester P-70 manufactured by Kayaku Nouri ■ (Note-2): t-butyl peroxy bivalate, manufactured by Kayaku Nouri ■ (Note-3) - Heat distortion temperature was measured according to ASTM-D-648.

- Izod impact strength was measured according to JIS K-6911. (t: 6 mm, flat width) - The falling ball impact height was measured according to JIS K-6718. (
t: 6+u+, 1 steel ball, weight 225g) - Cutting workability was determined by the degree of chipping of the cut surface by a rotating circular saw blade (manufactured by Shincho Kogyo ■, running saw) and the degree of chipping of the cut surface, and whether a good cut surface was obtained.
Evaluation was made based on the continuous cutting length of a cured product with a thickness of mm.

Comparative Example 1 Polymethyl methacrylate (Acrivet MDOO1,
27 parts by weight (manufactured by Mitsubishi Rayon ■) were dissolved in 73 parts by weight of methyl methacrylate to obtain methyl methacrylate silica having a viscosity of 5 voids.

Next, 200 parts by weight of aluminum hydroxide (Hisilite H-320, average particle size 3.5 microns, manufactured by Showa Denko ■) was kneaded into this resin liquid using a high-speed stirrer, and then,
0.8 parts by weight of Kaya Ester 0 (manufactured by Kayaku Nuri ■) as a curing agent was added, and after mixing, defoaming was carried out under reduced pressure to obtain a resin blend. The viscosity of this resin compound was 200 voices at a liquid temperature of 30° C., and it was difficult to cast because it had many residual bubbles and poor fluidity. This resin compound is 1000X600X
The mixture was poured into a casting mold of 60° C., cured at 60° C., cured in 20 minutes, and then post-cured at 110° C. for 2 hours.

As shown in Table 3, the physical properties of the obtained cured product were poor in impact resistance.

Comparative Example 2 A cured product was obtained by carrying out the same operation as in Example 1 except that the composition did not contain urethane acrylate as shown in Table 3.

The physical properties of the obtained cured product are as shown in Table 3, and it was inferior in impact resistance and cutting workability.

Comparative Example 3 30 parts by weight of trimethylolpropane methacrylate, 50 parts by weight of styrene, 20 parts by weight of methyl methacrylate,
and 5 parts by weight of a silane coupling agent (KBM-503, manufactured by Shin-Etsu Chemical) were mixed to obtain a monomer mixture.

Next, aluminum hydroxide (Hisilite H-320, average particle size 3.5 microns, manufactured by Showa Denko ■) was added to this mixed solution.
300 parts by weight were kneaded using a high-speed stirrer, then 0.5 parts by weight of Kayaester P-70 (t-butyl baroxybiparade, manufactured by Kayaku Nouri) as a hardening agent was added, and after mixing, the mixture was decompressed under reduced pressure. A formulation was obtained by foaming. The viscosity of this compound was 10 voids at a liquid temperature of 30°C.Next, this compound was poured into a 1000 x 600 x 6a+m casting mold and cured at 50°C. It was post-cured for 2 hours at ℃.

The cured product was milky white and had a beautiful light-scattering translucency similar to that of an astronomical stone, and was flame retardant.As shown in Table 3, the heat distortion temperature was as high as 230°C. It was inferior in impact resistance and machinability.

Comparative Example 4 A silane coupling agent (KB
Aluminum hydroxide (Hysilite H-320
, average particle size 3.5 microns, manufactured by Showa Denko ■) were kneaded using a high-speed stirrer, and then 0.8 parts by weight of a curing agent Kaya Ester 0 (manufactured by Kayaku Nuri ■) was added. After mixing, the mixture was defoamed under reduced pressure to obtain a resin blend.

The viscosity of this resin compound was 300 voids at a liquid temperature of 30° C., with many residual bubbles and poor fluidity, making casting difficult.

This resin mixture was poured into a 101,000 x 600 x 6 casting mold and cured at 60°C, cured in 50 minutes, and then post-cured at 110°C for 2 hours.

As shown in Table 3, the physical properties of the obtained cured product had problems in impact resistance and machinability.

Comparative Example 5 A cured product was obtained by carrying out the same operation as in Example 1 except that the composition was as shown in Table 3.

The physical properties of the obtained cured product are as shown in Table 3, and it was inferior in impact resistance and cutting workability.

Comparative Example 6 A cured product was obtained in the same manner as in Example 5 except that urethane acrylate was used and the composition shown in Table 3 was used. The physical properties of the obtained cured product are shown in Table 3, and the cutting workability was good, but the viscosity of the resin compound was 50°C at a liquid temperature of 30°C.
There was a high level of voids, and there were many residual bubbles (and it was difficult to cast the mold).

Comparative Example 7 A cured product was obtained in exactly the same manner as in Example 3, except that the composition was as shown in Table 3 and no polyfunctional acrylate was used.

The physical properties of the obtained cured product are as shown in Table 3, and although the cutting workability was good, the heat distortion temperature was low and it was poor in practical use.

Example 6 10 parts by weight of urethane acrylate (5) obtained in Reference Example 5, 40 parts by weight of styrene, 5 parts by weight of tromethylolpropane trimethacrylate, -silane coupling agent (
KBM-503, γ-methacryloxytrimethoxysilane, manufactured by Shin-Etsu Silicone ■) 1 part by weight and curing agent (barbutyl 0,1-butylperoxy-2-ethylhexanoate, manufactured by NOF ■) 0.5 part by weight was added to a Nigu and dissolved in a sieve for 30 minutes at room temperature. To this, 300 parts by weight of aluminum hydroxide (Hisilite H-320, average particle size 3.5 microns, manufactured by Showa Denko ■) was added, and further methyl methacrylate/methyl acrylate was copolymerized at a weight ratio of 9:1. Acrylic resin (average molecular weight 10
After adding 45 parts by weight of 10,000 parts by weight, the mixture was kneaded and aged at 40°C for 60 minutes, and then cooled to room temperature to obtain a hard rubbery clay-like molding material.

Next, 300g of this molding material was cut with a cutter knife, and held at 100°C for 20 minutes under a pressure of lOOkg/Cm'' using a compression molding mold for tray molding, and the size was 140! A tray-shaped cured product of 180a+m×6mm was obtained.

The performance of the obtained cured product was measured according to Examples 1 to 5, and as shown in Table 4, the product was excellent in impact resistance and machinability.

Comparative Example 8 A tray-shaped cured product having the composition shown in Table 3 was obtained in the same manner as in Example 6 except that the urethane acrylate (5) used in Example 6 was not used.

As a result of measuring the performance of the obtained cured product according to Examples 1 to 5, as shown in Table 4, there was a problem in cutting workability.

Table 4 (Note-1) Acrylic resin Copolymer of methyl methacrylate/methyl acrylate in a weight ratio of 9:1 (Note-2) t-Butylperoxy-2-ethyl manufactured by Barbutyl 08 Oils & Fats ■ Hexanoate (Note-3) Silane coupling agent KBM-503 manufactured by Shin-Etsu Silicone ■, γ-methacryloxypropyltrimethoxysilane (Note-4) Same as (Note-3) in Table 2

Claims (1)

[Claims] 1. General formula ▲ Numerical formula, chemical formula, table, etc. ▼ (However, R_1 is hydrogen or a methyl group, R_2 is a glycol residue having 2 to 4 carbon atoms, Polyisocyanate or a polyisocyanate residue of an elastomer having a hydroxyl group at the terminal group, n is a positive number of 2 to 3.) The number average molecular weight (@Mn@) is 2,500 to 30,000. , and the weight average molecular weight (@Mw@) is 7,000 ~
40,000 urethane (meth)acrylate (A)2
~30 parts by weight and aliphatic polyfunctional (meth)acrylate 3
40 parts by weight, a radically polymerizable monomer (B) consisting of 30 to 95 parts by weight of a monofunctional aromatic vinyl compound, and 0 to 65 parts by weight of a monofunctional alkyl (meth)acrylate; The total weight of (B) is 100 parts by weight. After dispersing 100 to 800 parts by weight of the metal oxide hydrate (II) in the resin composition (I), the impact resistant product is obtained by molding and curing. Artificial marble with excellent durability and machinability. 2. The artificial marble according to claim 1, wherein the average particle size of the metal oxide hydrate is 5 microns or less. 3. Urethane (meta)
The artificial marble according to claim 1 or 2, wherein the @Mw@/@Mn@ ratio of the acrylate is 2 or less. 4. Claim 1 comprising 3 to 10 parts by weight of aliphatic polyfunctional (meth)acrylate in the radically polymerizable monomer (B).
The artificial marble according to any one of 3 to 3. 5. Any one of claims 1 to 4, wherein X in the general formula representing urethane (meth)acrylate (A) is a polyether polyisocyanate residue with n of 2 to 3 obtained by reacting polyether and isophorone diisocyanate. Artificial marble according to item 1. 6. The artificial marble according to claim 5, wherein the polyether has polypropylene glycol units.