Solid molding material and molded article made therefrom

Abstract

To provide a solid molding material that can be molded by press molding and gives a molding that, if scratched, can render the scratches inconspicuous.SOLUTION: The present invention relates to a solid molding material used for a molding such as artificial marble. The solid molding material has at least one of an unsaturated polyester resin and a vinyl ester resin as a matrix resin. Relative to the matrix resin 100 pts.wt., liquid oil is contained by 2-15 pts.wt. A filler used herein contains silica of 50% or more.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a solid molding material that can be used for molding artificial marble and the like. More specifically, it relates to a solid molding material that can be used to mold artificial marble that is less likely to show scratches even when scratched, with good productivity by press molding.

Background Art

[0002] Artificial marble has high design quality and excellent heat resistance and rigidity, so it is suitably used for various applications such as countertops (counters) of system kitchens and washbasin vanities, sinks, or bathtubs, and surface materials of furniture. However, artificial marble is easily scratched on the surface by friction or the like. Scratches formed by weak frictional force may not be noticeable depending on the viewing angle (the way of light reflection), but scratches formed by strong frictional force become white lines and are noticeable regardless of the viewing angle. In particular, artificial marble used in the vicinity of water, such as a kitchen counter, has many opportunities to rub against pottery, metal pans, etc., and it is desired to improve scratch resistance. In order to solve such problems, artificial marble with improved scratch resistance by containing hard particles (Patent Document 1) and artificial marble with improved scratch resistance by forming a hard protective film on the surface (Patent Document 2) have been proposed. However, even when scratch resistance (scratch resistance) is improved by these methods, it is difficult to completely prevent the formation of scratches. Once scratched, it becomes a white line, and the darker the color of the artificial marble, the more noticeable the formed scratches become.

[0003] Furthermore, methods have been proposed to make scratches that have already formed in this way less noticeable. For example, Patent Document 3 below proposes a flame-retardant resin product with excellent surface scratch and whitening resistance, formed from a composition comprising a resin component mainly consisting of 90-60% by weight of a copolymer of ethylene and an unsaturated carboxylic acid or its derivative or vinyl ester, and 1-40% by weight of an olefin polymer modified with an unsaturated carboxylic acid or its derivative, and a scratch and whitening inhibitor made from alkylene oxide adducts of compounds selected from higher fatty acids, their esters, amides or metal salts, silicone, or partially fatty acid esters of polyhydric alcohols, aliphatic alcohols, fatty acids, aliphatic amines, fatty acid amides, alkylphenols and alkylnaphthols. Patent Document 4 below proposes a resin composition characterized by obtaining a film with excellent scratch resistance by adding silicone oil to an acrylic resin, and a sheet made from this resin composition. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2009-263662 [Patent Document 2] Japanese Patent Publication No. 2005-132673 [Patent Document 3] Japanese Patent Application Publication No. 9-169876 [Patent Document 4] Japanese Patent Application Publication No. 11-35778 [Overview of the project] [Problems that the invention aims to solve]

[0005] The resin compositions described in Patent Documents 3 and 4 above all relate to molded articles made of thermoplastic resins, and therefore have low rigidity and heat resistance, making them unsuitable for artificial marble, such as kitchen countertops, where rigidity and heat resistance are required. Furthermore, they are not solid materials with improved handling properties, like BMC or SMC, and are not molded by press molding. Therefore, the object of the present invention is to provide a solid molding material that can be molded by press molding, is less prone to scratches, and is particularly capable of molding artificial marble. [Means for solving the problem]

[0006] According to the present invention, at least one of an unsaturated polyester resin or a vinyl ester resin is used as the matrix resin, and liquid oil is contained in an amount of 2 to 15 parts by weight per 100 parts by weight of the matrix resin, and filler is contained in an amount of 45 to 85% by weight of the total molding material, with silica accounting for more than 70% of the filler used. A solid molding material that, according to the solid-liquid determination test based on ASTM D 4359-90, is not determined to be a liquid under temperature conditions of 50°C. A solid molding material characterized by the above is provided.

[0007] In the solid molding material of the present invention, 1. The liquid oil is one or more of the following: silicone oil, paraffin, vegetable oil, or hydraulic oil. 2. The liquid oil is dimethyl silicone oil. 3. The silica is surface-treated crystalline silica. 4. The average particle size of the silica is in the range of 5 to 150 μm. 5. The silica is a blend of two or more types of silica with different average particle sizes. 6. The solid-liquid determination test based on ASTM D 4359-90 does not determine the substance to be a liquid at a temperature of 50°C. This is preferable.

[0008] According to the present invention, a solid molding material is also formed by press molding. A molded product in which a sapphire needle with a tip radius of R0.15 mm is placed vertically on the molded product, and when a load is applied to the tip and moved at a speed of 1000 mm / min, the minimum load at which a white scratch can be observed on the surface of the molded product is 140 g or more. A molded product characterized by the above is provided. [Effects of the Invention]

[0009] Molded articles such as artificial marble obtained from the solid molding material of the present invention maintain excellent appearance characteristics over a long period of time because scratches on the surface of the molded article are less noticeable due to the presence of liquid oil in the molded article. In particular, scratches can be made less noticeable even in black molded articles, which tend to show scratches easily. This is evident from the results of the examples described later. Specifically, in Examples 1 to 5 and Comparative Example 1, which have almost the same composition except for the presence or absence of liquid oil, the minimum load at which scratches are recognized (scratch test value) is greater in the molded articles of Examples 1 to 5, which contain liquid oil, compared to the molded article of Comparative Example 1, indicating that scratches are less noticeable. Furthermore, the solid molding material of the present invention is not determined to be a liquid under a temperature of 50°C according to the solid-liquid determination test based on ASTM D 4359-90, meaning it is solid even under a temperature of 50°C, thus offering excellent handling properties and enabling the molding of molded products such as artificial marble by press molding. [Modes for carrying out the invention]

[0010] (Matrix resin) In the solid molding material of the present invention, an unsaturated polyester resin and / or a vinyl ester resin are used as the matrix resin. These resins can be used individually or in blends.

[0011] Unsaturated polyester resins are generally obtained by esterifying unsaturated alkyds, which are produced by using an unsaturated acid such as maleic anhydride or fumaric acid in combination with a saturated basic acid such as phthalic anhydride, isophthalic acid, terephthalic acid, adipic acid, sebacic acid, succinic acid, or gluconic acid, with glycols such as propylene glycol, ethylene glycol, diethylene glycol, neopentyl glycol, or hydrogenated bisphenol A, and then dissolving these alkyds in vinyl monomers such as styrene monomer, vinyltoluene, triallyl cyanurate, diallyl phthalate, or methyl methacrylate monomer. Vinyl ester resins are compounds having multiple acryloyl groups or methacryloyl groups in their molecules, obtained by reacting compounds having multiple epoxy groups in their molecules, such as bisphenol A type epoxy resin or novolac type epoxy resin, with acrylic acid or methacrylic acid. For unsaturated polyester resins and vinyl ester resins, it is preferable to use grades that have been used in the conventional production of SMC and BMC.

[0012] In addition, conventional BMC and SMC low-shrinkage agents can be used, and 5 to 50% by weight of the unsaturated polyester resin and / or vinyl ester resin can be replaced with the low-shrinkage agent. The low-shrinkage agent is prepared by dissolving a thermoplastic resin such as polystyrene resin, styrene-acrylic acid copolymer, styrene-vinyl acetate copolymer, styrene-butadiene copolymer, styrene-olefin copolymer, or poly(meth)acrylic acid ester in a vinyl monomer such as styrene monomer, vinyl toluene, triallyl cyanurate, diallyl phthalate, or methyl methacrylate. The concentration of the thermoplastic resin in the low-shrinkage agent is 5 to 50% by weight. Additionally, three-dimensional resin powders of styrene-based, acrylic-based, vinyl acetate-based, and copolymer-based resins thereof, with a crosslinking density of 0.01 to 5%, may be used as low-shrinkage agents.

[0013] (Liquid oil) In the solid molding material of the present invention, it is important that the liquid oil is contained in an amount of 2 to 15 parts by weight, particularly 3.5 to 11 parts by weight, per 100 parts by weight of the matrix resin. This makes it possible to significantly reduce the visibility of scratches on the surface of the molded product compared to molded products that do not contain liquid oil. In the present invention, the liquid oil that can be suitably used is preferably one or more of the following: silicone oil, paraffin, vegetable oil, and hydraulic oil, with silicone oil being particularly preferred. Examples of silicone oils include dimethyl silicone oil, methylphenyl silicone oil, methylhydrogen silicone oil, and modified silicone oils obtained by introducing organic groups into dimethyl silicone oil. Specifically, as straight silicone oils, dimethyl silicone oil, methylphenyl silicone oil, etc. can be preferably used. Examples of modified silicone oils include reactive silicone oils such as amino modification, epoxy modification, carbinol modification, mercapto modification, carboxyl modification, methacryl modification, polyether modification, phenol modification, and one-terminal reactivity / heterofunctional group modification, and non-reactive silicone oils such as polyether modification, aralkyl modification, fluoroalkyl modification, long-chain alkyl modification, higher fatty acid ester modification, and phenyl modification. In the present invention, dimethyl silicone oil can be particularly preferably used. The kinematic viscosity of the liquid oil is preferably in the range of 1 to 100000 mm 2 / s.

[0014] It is important that the liquid oil is contained in the above range. When the content is less than the above range, the effect of making scratches less noticeable cannot be fully expressed. On the other hand, when the content is more than the above range, the hardness of the obtained molded product decreases, making it easier for scratches to occur, so there is a risk that the scratches will be more noticeable overall. Also, there is a risk that the liquid oil will bleed out and make the molded product sticky.

[0015] (Silica) In the solid molding material of the present invention, it is important to use silica as a filler, and particularly important that the proportion of silica in the filler used is 50% or more, particularly 70% or more. By adding this inorganic filler, the rigidity of the molded product can be increased, and particularly by using silica, the scratch resistance can be improved. For silica, crystalline silica is preferable from the viewpoint of improving scratch resistance, and surface-treated crystalline silica is particularly preferable. When silica is surface-treated with a coupling agent or other surface treatment agent, the bond between the resin and silica is strengthened, improving mechanical strength and reducing the mixing viscosity, which allows for a larger amount of silica to be added, thus improving scratch resistance. Examples of surface treatment agents include silane coupling agents, titanate coupling agents, and aluminum coupling agents. However, silane coupling agents containing vinyl groups, such as vinylsilane and (meth)acrylate silane, are preferred because they strengthen the bond between the resin and silica. Surface-treated silica may be of a single type, or two or more different surface treatment agents may be used in combination.

[0016] The average particle size of silica is preferably in the range of 5 to 150 μm, and particularly preferably in the range of 10 to 100 μm. This range results in a viscous mixture, but its low viscosity makes it easy to mix. The average particle size of silica mentioned above is the median diameter (d50) value measured using a laser diffraction scattering particle size distribution analyzer. Provided that the average particle size of the silica is within the above range, a blend of two or more silicas with different average particle sizes can be suitably used. In the case of two types, although not limited to this, silica with an average particle size in the range of 5 to 80 μm can be combined with silica in the range of 30 to 170 μm. This allows for a larger silica filling amount, improving the scratch resistance of the resulting molded product. The blending ratio of the two types of silica varies depending on the average particle size of the silicas to be blended, and the blending ratio (weight ratio, silica with smaller average particle size: silica with larger average particle size) is preferably in the range of 99:1 to 20:80, and particularly preferably in the range of 90:10 to 30:70.

[0017] In the solid molding material of the present invention, silica is an essential component as a filler, and it is preferable that the silica content be 100%. However, as long as the amount of silica is 50% or more of the total filler, and especially 70% or more, other inorganic fillers can be used in combination for the remaining amount. While not limited to these, other fillers that can be used include, for example, aluminum oxide, aluminum hydroxide, magnesium hydroxide, calcium aluminate, calcium carbonate, magnesium carbonate, glass powder, mica, synthetic fluorphlogopite, talc, kaolin, mica, sericite, anhydrous silicic acid, barium sulfate, etc. In the case of materials harder than silica, it is preferable to include, for example, aluminum oxide in combination with silica, which can further improve the surface hardness of the resulting molded product. The amount of silica-containing filler added is not constant. For example, the amount added will be less when the amount of resin in the molding material is small or high viscosity, when the particle size distribution of the filler is narrow, or when the amount of glass fiber added is large. However, it is preferable to include it in the range of 45-85% by weight of the total molding material, especially in the range of 55-85% by weight. If the filler content is less than the above range, the viscosity during manufacturing will decrease, making manufacturing more difficult. Furthermore, the molded product will have a higher shrinkage rate, making it more prone to deformation, and its hardness will decrease, making it more susceptible to scratches. On the other hand, if the filler content is more than the above range, it will be more difficult to mix in a mixer, and the mixture will be more prone to dispersion problems compared to when it is within the above range.

[0018] (others) The solid molding material of the present invention may contain, in addition to the matrix resin, liquid oil, and silica-containing filler, various additives that have been conventionally incorporated into SMC and BMC, such as polymerization initiators, polymerization inhibitors, internal release agents, thickeners, pigments, and glass fibers, according to known formulations. Known polymerization initiators can be used, such as organic peroxides including diacyl peroxides, peroxyesters, alkyl peroxides, and peroxyketals. Known polymerization inhibitors can be used, such as hydroquinone, trimethylhydroquinone, pt-butylcatechol, toluhydroquinone, and p-benzoquinone. Known internal release agents can be used, such as fatty acids like stearic acid, fatty acid salts like zinc stearate, paraffin wax, and carnauba wax. Known thickeners can be used to solidify the molding material, and examples include metal oxides and metal hydroxides such as magnesium oxide, magnesium hydroxide, calcium oxide, and calcium hydroxide, as well as isocyanate compounds. Glass fibers are primarily incorporated to increase the strength and / or impact resistance of molded products. Types of glass include E-glass, C-glass, and T-glass, with fiber diameters ranging from 5 to 25 μm. Surface treatment agents used as raw materials include vinyl acetate resin, acrylic resin, epoxy resin, and silane coupling agents. When glass fibers are incorporated as needed, those commonly used in BMC (Body Metal Condensation) are preferred.

[0019] The pigment is not particularly limited, and conventionally known pigments such as titanium dioxide and carbon black can be used without restriction. However, the solid molding material of the present invention can suppress the visibility of scratches, and is therefore particularly suitable for use in black molded products that are prone to scratches, and is especially suitable when it contains black composite oxide pigments, carbon black, etc. as the pigment.

[0020] (Manufacturing of solid molding materials) The solid molding material of the present invention can be manufactured by conventionally known manufacturing methods, except that the liquid oil and silica content is used under the conditions described above. Specifically, additives such as liquid oil and silica are added in predetermined proportions to the molding material containing the unsaturated polyester resin and / or vinyl ester resin described above, and a kneaded product is prepared using conventionally known kneading equipment such as a kneader or planetary mixer. Next, if necessary, the kneaded product is enclosed in packaging material that has gas barrier properties for the vinyl monomer contained in the kneaded product. Then, if necessary, the product is thickened by heating at room temperature to 50°C for 16 to 48 hours to produce a solid molding material. As described above, the solid-forming material of the present invention obtained in this manner is not determined to be a liquid under a temperature of 50°C in a solid-liquid determination test based on ASTM D 4359-90, i.e., it has a solid state, and can be used as BMC or SMC, and has excellent handling properties.

[0021] (molded product) To mold artificial marble or the like using the solid molding material of the present invention, the solid molding material of the present invention is placed in a mold adjusted to a temperature of 120 to 160°C. Then, the mold is closed and the molding pressure is increased at 1 to 15 MPa for 1 to 2 minutes per 1 mm of wall thickness to obtain the molded product. The obtained molded product has a pencil hardness (according to JIS K5600) of less than 9H and a Barcol hardness (according to JIS K6911) of less than 75, but due to the inclusion of liquid oil, it exhibits the excellent effect of making scratches less noticeable. Although the mechanism by which scratches are less noticeable on the molded product of the present invention is not clear, it is presumed that a certain amount of liquid oil present in the molded body seeps out onto the surface of the molded body, reducing the coefficient of friction on the surface of the molded body, thereby improving scratch resistance and suppressing diffuse reflection of light, making scratches less noticeable. [Examples]

[0022] The following provides specific examples to illustrate this point. (Example 1) The raw materials, such as the matrix shown in Table 1, and the liquid oil shown in Table 2 were blended in the composition shown in Table 3 and kneaded in a kneader. The resulting molding material was wrapped in nylon film and heated for 24 hours under a temperature of 45°C. The obtained solid molding material was placed in a mold where the temperature of the molding surface was adjusted to 145°C and the temperature of the back surface to 130°C, and pressurized at a pressure of 7 MPa for 8 minutes to obtain a molded product with a wall thickness of 6 mm. The scratch test values ​​of the obtained molded products were measured. The results are shown in Table 3. The scratch test was performed by vertically placing a sapphire needle with a tip radius of R0.15 mm onto the molded product, applying an arbitrary load to the tip, and moving it at a speed of 1000 mm / min. The minimum load at which a white scratch was observed on the molded surface was defined as the scratch test value.

[0023] (Examples 2-20 and Comparative Examples 1-6) Molded plates were prepared in the same manner as in Example 1, except for the changes in composition shown in Tables 3-5, and scratch test values ​​were measured. The results are shown in Tables 3-5. Examples 15 and 16 are comparative examples.

[0024] [Table 1]

[0025] [Table 2]

[0026] [Table 3]

[0027] [Table 4]

[0028] [Table 5]

Claims

1. A solid molding material comprising at least one of an unsaturated polyester resin or a vinyl ester resin as a matrix resin, containing 2 to 15 parts by weight of liquid oil per 100 parts by weight of the matrix resin, containing a filler in an amount of 45 to 85% by weight of the total molding material, and having a silica content of more than 70% of the filler used, characterized in that it is not determined to be a liquid at a temperature of 50°C in a solid-liquid determination test based on ASTM D 4359-90.

2. The solid molding material according to claim 1, wherein the liquid oil is one or more of silicone oil, paraffin, vegetable oil, and hydraulic oil.

3. The solid molding material according to claim 1 or 2, wherein the liquid oil is dimethyl silicone oil.

4. The solid molding material according to any one of claims 1 to 3, wherein the silica is surface-treated crystalline silica.

5. The solid molding material according to any one of claims 1 to 4, wherein the average particle size of the silica is in the range of 5 to 150 μm.

6. The solid molding material according to any one of claims 1 to 5, wherein the silica is a blend of two or more types of silica with different average particle sizes.

7. A molded article made by press-molding a solid molding material according to any one of claims 1 to 6, characterized in that the scratch test value, which is the minimum load at which a white scratch can be observed on the surface of the molded article when a sapphire needle with a tip radius of R0.15 mm is placed vertically on the molded article and a load is applied to the tip and moved at a speed of 1000 mm / min, is 140 g or more.

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