JPH0557220B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to artificial marble that is useful as a building material and has excellent impact resistance and machinability. [Prior Art] Artificial marble using hydrated metal oxides as a filler has been known. For example, methyl methacrylate artificial marble is made by kneading aluminum hydroxide into methyl methacrylate syrup 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 syrup. Those using vinyl ester resin dissolved in styrene are known. These syrups 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 marble-like articles by adding additives. [Problems to be solved by the invention] However, the artificial marble cast using the above-mentioned syrup etc. has a high viscosity, so there are restrictions on the amount and size of the filler that can be used. There is. For example, when making artificial marble with a high filler content that has excellent heat resistance and flame retardancy by using a large amount of filler,
It is difficult to disperse the filler and it is not possible to obtain a beautiful product, and 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. . Therefore, these artificial marbles have the disadvantage that cracks and pinholes occur on the surface due to poor dispersion of the filler or the use of a filler with a large particle size, resulting in poor impact resistance. It also had drawbacks in terms of water resistance, such as hot water penetrating through pinholes and causing blisters. On the other hand, methyl methacrylate resin, unsaturated polyester resin, and vinyl ester resin, which have been used as base resins for artificial marble, cannot be said to have excellent impact resistance, and premix molding materials using these resins as base resins heating and
Artificial marble obtained by pressure molding does not have sufficient strength even though it is improved by glass fibers, tends to have glass fiber patterns, and has problems in 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 Patent Laid-Open No. 128956/1983). issue). but,
This monomer cured product-based artificial marble was not as easy to handle as methyl methacrylate resin-based artificial marble during cutting, and had the drawbacks of high cutting resistance and easy chipping of the cut cross section. . Artificial marble is used for kitchen tops, table tops, wall materials, etc., but it is often used as a thick plate by butting the cut surfaces of artificial marble boards together or by gluing several boards together. Particularly if there are chips at the corners, the joints will be noticeable and the appearance will be seriously impaired, making it impossible to see the beautiful integrated artificial marble. In order to obtain a chip-free cut surface, it was necessary to reduce the machining speed and increase the number of tool updates. Methyl methacrylate artificial marble also had this problem, although it was better than the aforementioned artificial marble. Artificial marble based on unsaturated polyester resin or vinyl ester resin also has the same drawbacks as the above-mentioned artificial marble. The present invention aims to improve the current state of the art, and provides an artificial marble that has excellent impact resistance and machinability, is highly transparent, and has an elegant appearance. [Means and effects for solving the problem] As a result of various studies by the present inventors, after dispersing a specific amount of a specific filler into a specific resin composition,
The present invention was completed by discovering that molded and hardened artificial marble satisfactorily achieves the purpose. That is, the present invention has the general formula (However, R ₁ is hydrogen or a methyl group, R ₂ is a glycol residue having 2 to 4 carbon atoms, n is a positive number of 2 to 3), the number average molecular weight measured by GPC method is 2500 to 30000, and the weight average molecular weight is
7000~40000 urethane (meth)acrylate (A)
2 to 30 parts by weight, 3 to 40 parts by weight of aliphatic polyfunctional (meth)acrylate, and 30 parts by weight of monofunctional aromatic vinyl compound.
~95 parts by weight and a polymerizable monomer (B) consisting of 0 to 65 parts by weight of a monofunctional alkyl (meth)acrylate, and the total weight parts of (A) and (B) are 100 parts by weight. The present invention relates to an artificial marble having excellent impact resistance and cutting workability, which is obtained by dispersing 100 to 800 parts by weight of a metal oxide hydrate () in a resin composition () and then molding and curing it. When carrying out the present invention, if the resin composition () and the metal oxide hydrate () are mixed using a mixer capable of high-speed stirring such as a disk bar or a homomixer, thixotropy may temporarily occur during mixing. However, in the end, even if a large amount of metal oxide hydrate (more than 300 parts by weight) is added to 100 parts by weight of the resin composition, it is still suitable for casting. Low viscosity formulations of 10-100 poise are 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. It is possible to mix even if a large amount of hydrated products is added, up to about 800 parts by weight, and a dough-like molding material with excellent fluidity when pressurized can be obtained. The thus obtained low-viscosity mixture or green bread-like molding material can be easily cast or molded under heat and pressure, especially when the amount of filler is about 250 to 400 parts by weight.
Beautiful translucent, milky-white artificial marble is obtained, and at a high filler content of 400 to 800 parts by weight, milky-white artificial marble with a high degree of flame retardancy is obtained. 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 using ordinary woodworking tools. The urethane (meth)acrylate (A) used in the present invention is a polyether, a polyester, or a polyester having a urethane bond in the main chain and a (meth)acryloyl group at the terminal as represented by the above general formula.
and an elastomer, and the urethane (meth)acrylate (A) 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 isocyanate compound and a hydroxyalkyl (meth)acrylate. can. Polyether polyols used to obtain urethane (meth)acrylate (A) include, for example, polyethylene glycol, polypropylene glycol, glycerin-based polypropylene glycol triols, polytetramethylene glycol, polyhexamethylene glycol, and polyester polyols. Examples include polybasic acids such as phthalic acid, isophthalic acid, maleic acid, adipic acid, and trimellitic acid; and polybasic acids such as ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, and trimethylolpropane. Condensation reaction products with alcohols, ring-opening polymers such as ε-caprolactone, and elastomers include hydroxyl-terminated polydienes such as hydroxyl-terminated polyisoprene and polybutadiene, and copolymerizable monomers. Examples include polymers. Examples of polyfunctional isocyanate compounds include tolylene diisocyanate, diphenylmethane diisocyanate, tetramethylene glycol diisocyanate, 1,4-cyclohexyl diisocyanate, isophorone diisocyanate,
Examples include triphenylmethane triisocyanate, dimethyltriphenylmethane triisocyanate, etc. Among them, urethane (meth)acrylate obtained using polyether polyisocyanate obtained by reacting polyether and isophorone diisocyanate ( When A) is used, it is desirable because it provides artificial marble with excellent weather resistance and less change in surface color over time. In addition, since urethane acrylate with a narrow molecular weight distribution can be easily obtained, the viscosity of the molding material is low, easy to handle, and artificial marble with excellent impact strength and machinability can be obtained, which is desirable. Furthermore, 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 add isophorodiisocyanate to polypropylene glycol that has been dehydrated under reduced pressure so that the molar ratio of NCO:OH is approximately 2:1, and to react 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 about 1:1, and reacting with dibutyltin dilaurate or the like as a catalyst. The number average molecular weight () of the urethane (meth)acrylate used in the present invention is in the range of 2,500 to 30,000, and the weight average molecular weight () is in the range of 7,000 to 40,000.
The number of (meth)acryloyl groups per molecule of (A) ranges from 2 to 3. Preferably 3000 ~
15,000, is 8,000 to 35,000, more preferably 8,000 to 12,000, / ratio (D
value) is 2 or less. When is less than 2,500 or less than 7,000, the obtained cured product is
Compared to the artificial marble of No. 128956, the impact resistance and chipping of the cut section are not significantly improved. is 30000
If it is larger than 40,000, the urethane (meth)acrylate has a high viscosity and is difficult to handle, and the obtained cured product will have residual bubbles, making it unsuitable in terms of appearance and strength. As shown in Example 4, even if , is 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 value of less than 2 satisfies the three properties of machinability, impact resistance, and heat resistance in the best balance, has minimal chipping on the cut surface, has high impact strength, and has a heat distortion temperature that is sufficient for practical use. You can get high quality artificial marble. Radical polymerizable monomer (B) used in the present invention
The essential components are 3 to 40 parts by weight of aliphatic polyfunctional (meth)acrylate, 30 to 95 parts by weight of monofunctional aromatic vinyl compound, and 0 to 65 parts by weight of monofunctional alkyl (meth)acrylate. 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 and 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 marble-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, propylene glycol di(meth)acrylate, butylene glycol di(meth)acrylate, 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. Alkyl (meth)acrylates include methyl methacrylate, ethyl methacrylate, t-butyl methacrylate, cyclohexyl methacrylate,
Examples include methacrylic esters such as benzyl methacrylate, and acrylic esters such as methyl acrylate, ethyl acrylate, n-butyl acrylate, and 2-ethylhexyl acrylate. 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, a thermoplastic polymer may be added to the monomer mixture in order to reduce shrinkage during molding and curing, prevent cracks and improve surface smoothness of the product. 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, and polyethylene. Conventionally known low-shrinkage polymers such as , polycaprolactam, and saturated polyester can be used alone or in combination. Thermoplastic polymers for low shrinkage are
If a large amount is added, it may increase the viscosity of the monomer mixture, making it difficult to obtain a casting compound with a high filler content, or resulting in a product with inferior transparency and heat resistance. be. Therefore, it is best to use the thermoplastic polymer for low shrinkage in as little amount as possible, and the urethane (meth)acrylate
It is desirable to use it in an amount of 200 parts by weight or less, more preferably 150 parts by weight or less, based on 100 parts by weight of the total amount of (A) and the radically polymerizable monomer (B). 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. This thickening polymer is
Thermoplastic polymers having two or more carboxyl groups in their side chains or terminals, such as methacrylate polymers obtained by copolymerizing 1 to 2% by weight of (meth)acrylic acid with methyl methacrylate, and maleated isoprene rubber; There are 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. As flame enhancers for these two types of thickening polymers, metal oxides and hydroxides such as magnesium oxide and magnesium hydroxide are used for the former, and polyfunctional compounds such as tolylene diisocyanate and isophorone diisocyanate are used for the latter. Isocyanates are used. The amount of the metal oxide hydrate () used is in the range of 100 to 800 parts by weight based on 100 parts by weight of the resin composition (). If the amount used is less than 100 parts by weight, flame-retardant artificial marble with excellent heat resistance cannot be obtained, and if it exceeds 800 parts by weight, it may become difficult to disperse into the resin composition () or during molding and curing. Fluidity is impaired and translucent and uniform artificial marble cannot be obtained. The metal oxide hydrate used in the present invention includes:
Examples include 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. Artificial marble containing 3 to 10 parts by weight of an aliphatic polyfunctional (meth)acrylate component in the resin composition () and using aluminum hydroxide has a heat distortion temperature of
100℃ or higher, heat resistance, hot water resistance, weather resistance,
A beautiful transparent to translucent milky-white artificial marble with excellent flame retardancy and high light transmittance can be obtained. When containing 10 to 40 parts by weight of aliphatic polyfunctional (meth)acrylate 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. Resin composition () and metal oxide hydrate ()
It is preferable to use a silane coupling agent when dispersing the silane because it improves the water resistance of the molded and cured product. Examples of the silane coupling agent include γ-methacryloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, vinyltriethoxysilane, and vinyltriacetoxysilane. The curing agent used when molding and curing is as follows:
For example, benzoyl peroxide, cyclohexane 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- to low-temperature curing agents can be used alone or together with organic amines or polyvalent metal salts as accelerators, but bis(4-t-butylcyclohexyl) peroxydicarbonate (4-t-butylcyclohexyl) is particularly preferred for casting purposes. Parkadox and PX
-16, manufactured by Nippon Kayaku Co., Ltd.). To specifically implement the present invention, first, for example,
2 to 30 parts by weight of urethane (meth)acrylate (A),
Preferably, a resin composition () consisting of 5 to 20 parts by weight and 70 to 98 parts by weight, preferably 80 to 95 parts of radically polymerizable monomer (B) is prepared, and 100 parts by weight of this resin composition () is prepared. 100 to 800 parts by weight of the metal oxide hydrate () is dispersed in the sample. At this time, the metal oxide hydrate () may be treated with a silane coupling agent in advance, or
Alternatively, a silane coupling agent corresponding to 0.1 to 2.0% based on the weight of the metal oxide hydrate () to be used is dissolved or dispersed in the resin composition (2), and then the metal oxide is hydrated. Object () can also be used. In addition to the metal oxide hydrate () added to the resin composition (), various fillers, reinforcing fibers such as glass fiber, and zinc stearate may be added, if necessary, in amounts within a range that does not impede the effects of the present invention. Mold release agents such as thixotropic agents, plasticizers, flame retardants, flame retardants, colorants, etc. may be added, and the curing agent is added in an amount equivalent to 0.5 to 3.0% based on the weight of the resin composition (). It is common to add As for the dispersion method, a high-speed stirrer, a pigment dispersion machine for paint production, or a kneading roll may be used to prepare a low-viscosity compound for casting, and to obtain a raw bread-like molding material for press molding. In order to
A low-speed, powerful kneading machine 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, proceed with preliminary curing at a temperature of, for example, 60℃, and if necessary,
It can be post-cured into a product by heating at 80-120°C. 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. [Effects of the Invention] The artificial marble of the present invention is an article with moderate stickiness and excellent impact resistance, and is easy to cut with wood cutting equipment, and defects such as chips and cracks do not occur on the cut surface. It has a beautiful transparent to translucent 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. (Example) Examples will be explained in more detail below.
These do not represent all of the invention. Reference example 1 Bifunctional polypropylene glycol (hereinafter referred to as PPG) with an average molecular weight of 400 was placed in a four-neck separable flask.
100 parts by weight of P-400 manufactured by Asahi Denka Kogyo Co., Ltd. (abbreviated as ) was added and dehydrated at 90° C. and 10 Torr for 2 hours. Cool this to 60℃, add 74.1 parts by weight of isophorone diisocyanate, and add dibutyltin dilaurate.
Add 0.033 parts by weight and react at 60°C for 18 hours. 19.3 parts by weight of hydroxyethyl acrylate was added to the obtained NCO-terminated PPG, and the reaction was further carried out at 60°C for 18 hours, resulting in a number average molecular weight of 3000 and a weight average molecular weight of 3000.
7200, D=2.4, and a viscous liquid urethane acrylate (1) having two acryloyl groups was obtained. Reference Examples 2 to 7 Urethane (meth)acrylates (2) to (7) were prepared according to the same procedure as in Reference Example 1 with the compositions shown in Table 1.
I got it.

[Table] Example 1 Urethane acrylate (1) obtained in Reference Example 130
parts by weight, 52 parts by weight of styrene, 13 parts by weight of methyl methacrylate, 5 parts by weight of ethylene glycol dimethacrylate, and a silane coupling agent (KBM
-503, manufactured by Shin-Etsu Chemical Co., Ltd.) were mixed to obtain a resin composition. Next, aluminum hydroxide (Hygilite H-320, average particle size 3.5 microns,
200 parts by weight of Showa Denko Co., Ltd.) were kneaded using a high-speed stirrer, and then 0.8 parts by weight of the curing agent Kayaester 0 (t-butylperoxy-2-ethylhexanoate, manufactured by Kayaku Nouri Co., Ltd.) After mixing, defoaming was carried out under reduced pressure to obtain a blend. The viscosity of this formulation is
It was 7.5 poise at 30℃. This mixture was poured into a casting mold of 1000 x 600 x 6 mm, cured at 60°C, cured in 30 minutes, and further post-cured at 120°C for 2 hours. The obtained cured product was milky white and had a beautiful light-scattering marble appearance, and as shown in Table 2, it was a product that exhibited flame retardancy and excellent impact resistance and machinability. Examples 2 to 5 Cured products were obtained in the same manner 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] Comparative example 1 Polymethyl methacrylate (acrypet)
27 parts by weight of MD001 (manufactured by Mitsubishi Rayon Co., Ltd.) was dissolved in 73 parts by weight of methyl methacrylate to obtain a methyl methacrylate syrup with a viscosity of 5 poise. Next, 200 parts by weight of aluminum hydroxide (Hygilite H-320, average particle size 3.5 microns, manufactured by Showa Denko K.K.) was kneaded into this resin solution using a high-speed stirrer, and then the curing agent Kayaester 0.0 (manufactured by Kayaku Nuri Co., Ltd.) was added, and after mixing, defoaming was carried out under reduced pressure to obtain a resin blend. The viscosity of this resin compound is 200 poise at a liquid temperature of 30°C, and there are many residual bubbles.
Moreover, its poor fluidity made casting difficult.
This resin mixture was poured into a casting mold of 1000 x 600 x 6 mm and cured at 60°C, which cured in 20 minutes, and was further 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
parts by weight, and silane coupling agent (KBM-
503 (manufactured by Shin-Etsu Chemical Co., Ltd.) were mixed to obtain a monomer mixture. Next, 300 parts by weight of aluminum hydroxide (Hygilite H-320, average particle size 3.5 microns, manufactured by Showa Denko K.K.) was kneaded into this mixed solution using a high-speed stirrer.
Next, the curing agent Kayaester P-70 (t-butylperoxypivalade, manufactured by Kayaku Nouri Co., Ltd.) was added at 0.5
Parts by weight were added, mixed and defoamed under reduced pressure to obtain a blend. The viscosity of this formulation was 10 poise at a liquid temperature of 30°C. Next, this mixture was poured into a casting mold of 1000 x 600 x 6 mm and cured at 50°C, which cured in 45 minutes, and was further post-cured at 120°C for 2 hours. The cured product has a marble-like translucency that beautifully scatters light, and is flame retardant.As shown in Table 3, the heat distortion temperature was as high as 230°C. It was inferior in impact resistance and cutting workability. Comparative Example 4 1.5 parts by weight of a silane coupling agent (KBM-503, manufactured by Shin-Etsu Chemical Co., Ltd.) was added to 100 parts by weight of vinyl ester resin (55 parts by weight of bisphenol A type epoxy acrylate resin dissolved in 45 parts by weight of styrene). Using a high-speed stirrer, 200 parts by weight of aluminum hydroxide (Hygilite H-320, average particle size 3.5 microns, manufactured by Showa Denko K.K.) was kneaded into the resin solution mixed with 0.0 (manufactured by Kayaku Nuri Co., Ltd.) was added, and after mixing, defoaming was carried out under reduced pressure to obtain a resin blend. The viscosity of this resin compound is 300 poise at a liquid temperature of 30°C, and there are many residual bubbles.
Moreover, its poor fluidity made casting difficult. This resin composition was poured into a casting mold of 1000 x 600 x 6 mm and cured at 60°C, which cured in 50 minutes, and was further 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 Example 1 except that the composition was as shown in Table 3.
A cured product was obtained by performing the same operation as above. 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 exactly 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 machinability was good, but the viscosity of the resin compound was as high as 50 poise at a liquid temperature of 30°C, and there were many residual bubbles and The mold was difficult. 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.

【table】

[Table] Example 6 Urethane acrylate (5) obtained in Reference Example 510
parts by weight, 40 parts by weight of styrene, 5 parts by weight of tromethylolpropane trimethacrylate, 1 part by weight of a silane coupling agent (KBM-503, γ-methacryloxytrimethoxysilane, manufactured by Shin-Etsu Silicone Co., Ltd.), and a curing agent (Perbutyl 0). , t-butylperoxy-2-ethylhexanoate, NOF Corporation
0.5 part by weight of the product (manufactured by Mimaki Co., Ltd.) was placed in a kneader, and kneaded and dissolved for 30 minutes at room temperature. To this, 300 parts by weight of aluminum hydroxide (Hygilite H-320), average particle size 3.5 microns, manufactured by Showa Denko K.K., was added, and methyl methacrylate/methyl acrylate was added in a weight ratio of 9:1.
45 parts by weight of an acrylic resin (average molecular weight: 100,000) obtained by copolymerization in a proportion of 100,000 yen was added, 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, use a cutter knife to remove 300% of this molding material.
g was cut out and held at 100℃ for 20 minutes under a pressure of 100Kg/cm ² using a compression molding mold for tray molding.
A tray-shaped cured product with dimensions of 140 mm x 180 mm x 6 mm 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】

【table】

Claims (1)

[Claims] 1. General formula (However, R ₁ is hydrogen or a methyl group, R ₂ is a glycol residue having 2 to 4 carbon atoms, is a positive number between 2 and 3.) The number average molecular weight () is
2500-30000, and weight average molecular weight ()
Urethane (meth)acrylate with 7000 to 40000
(A) 2 to 30 parts by weight, 3 to 40 parts by weight of aliphatic polyfunctional (meth)acrylate, and a monofunctional aromatic vinyl compound
A radically polymerizable monomer consisting of 30 to 95 parts by weight and 0 to 65 parts by weight of monofunctional alkyl (meth)acrylate
(B), and the total parts by weight of (A) and (B) are
Artificial marble with excellent impact resistance and machinability, obtained by dispersing 100 to 800 parts by weight of metal oxide hydrate () in 100 parts by weight of the resin composition (), and then molding and curing it. . 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 (meth)acrylate/
The artificial marble according to claim 1 or 2, wherein the ratio is 2 or less. 4. The artificial marble according to any one of claims 1 to 3, which contains 3 to 10 parts by weight of aliphatic polyfunctional (meth)acrylate in the radically polymerizable monomer (B). 5. 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 any one of the items. 6. The artificial marble according to claim 5, wherein the polyether has polypropylene glycol units.