Description ARTIFICIAL MARBLE

Technical Field

[1] The present invention relates to an artificial marble, and more particularly, to an artificial marble that can minimize a decrease in processibility since a transparent chip is uniformly dispersed within a matrix even though the transparent chip having high content of a resin component is used, and can express deep cubic feel even though such transparent chip is not introduced in excessive amounts. Background Art

[2] In general, an artificial marble totally refers to an artificially synthesized body that expresses the feel of a natural stone by adding an inorganic filler, a crosslinking agent and a curing agent (reaction initiator), etc. to a resin, and its representative example includes an acrylic artificial marble and an unsaturated polyester-based artificial marble.

[3] Recently, a technique using a transparent chip in order to express the transparency inherent in a natural stone in manufacturing such artificial marble is developed. For example, a transparent chip employing a resin of the same series as matrix is applied to an artificial marble, or a transparent chip employing a different kind of resin having a refractive index different that of from a matrix is applied to an artificial marble. Disclosure of Invention Technical Problem

[4] However, in the former case, if a transparent chip containing an elevated content of an acrylic resin is used in manufacturing an acrylic artificial marble, the transparent chip is not well dispersed in a resin slurry (i.e., matrix) and is ascended up to the mold top, i.e., the part corresponding to the rear surface layer of the artificial marble product, thereby forming locally centered part of the transparent chip, due to the difference in the specific gravity between the resin slurry of the acrylic resin syrup-inorganic filler constituting the matrix of an artificial marble and the transparent chip. Therefore, the processibility such as cutting and grinding the rear surface is remarkably deteriorated. Further, the transparent chip is present in very little amount at the mold bottom, i.e., the part corresponding the outer surface of the artificial marble, which is a part requiring a transparent chip substantially, and thus it was difficult to obtain the effect of introducing the transparent chip properly. Also, much chips more than the matrix volume must be introduced for a proper amount of the transparent chip to be present on the outer surface.

[5] Further, in the latter case, if a transparent chip manufactured by employing un-

saturated polyester is used in the matrix manufactured by employing an acrylic resin, the transparency of the artificial marble is excellent due to the different reflective index between the acrylic matrix and unsaturated polyester-based transparent chip, however, the adhesiveness between the transparent chip and the matrix is weakened, and thus minute gap occurs in the interface and further the chip is easily released from the matrix during bending process employing heat since the matrix and the transparent chip are consisted of each different resins.

[6] Meanwhile, as can be seen in FIG. 1, if a transparent chip is applied to an artificial marble, transparent feel by transmission of light is induced, however, the only effect of contrasting the transparent chip and the matrix is achieved over the whole surface of the artificial marble. Accordingly, deep cubic feel is not expressed, and thus there is only simple feel in the prior artificial marble.

[7] Accordingly, the present invention has been suggested in an effort to solve the problems occurring in the prior art. It is an object of the invention to provide an artificial marble that can minimize a decrease in processibility since a transparent chip is uniformly dispersed within a matrix even though the transparent chip having high content of a resin component is used, and simultaneously can provide the sufficient effect of introducing the transparent chip even though the transparent chip is not introduced in excessive amounts.

[8] Another object of the present invention is to provide an artificial marble having deep cubic feel.

Technical Solution

[9] In order to accomplish the above object, according to one aspect of the invention, there is provided an artificial marble including a base comprising 20 to 50 wt% of a resin syrup, 25 to 40 wt% of an inorganic filler, 0.05 to 2.5 wt% of a crosslinking agent and 0.05 to 2.5 wt% of a curing agent; 5 to 25 wt% of a transparent chip; and 3 to 15 wt% of a pearl transparent chip, wherein the ratio of resins is in the order of the transparent chip > the pearl transparent chip > the base.

[10] In the above, the pearl transparent chip is a chip in the form of chip-in-chip that is formed by manufacturing the first transparent chip having high content of the resin syrup and high transparency first, then adding the chip in manufacturing the second transparent chip having relatively low content of the resin syrup and simultaneously introducing an artificial pearl, which is formed by metal coating on a natural pearl or mica in order to increase the transparent feel of the first transparent chip by reflection effect. The pearl transparent chip having the same or similar specific gravity as matrix can be manufactured without significant decrease in transparency, and uniformly dispersed in the matrix.

[11] The present inventors completed the present invention by ascertaining that when the pearl transparent chip formed like this is introduced to a matrix together with a transparent chip having relatively low specific gravity, the transparent chip is uniformly distributed within the matrix even the transparent chip having high content of the resin component is used since the pearl transparent chip uniformly dispersed within the matrix prevents the transparent chip from ascending. According to the present invention, although the transparent chip having high content of the resin component is used, the decrease in processibility due to local centering of the transparent chip can be minimized, and simultaneously the sufficient effect of introducing the transparent chip on the outer surface can be obtained even though the transparent chip is not introduced in excessive amounts. Further, as can be seen in FIG. 2, the depth feel and cubic feel can be expressed depending the transparency difference, and more various cubic feel can be expressed due to the pearl transparent chip.

[12] The transparent chip is a chip having high transparency due to the high content of the resin syrup wherein the chip comprises 70 to 98 wt% of resin syrup, 1 to 20 wt% of a crosslinking agent and 1 to 2 wt% of a curing agent. The chip can further comprise below 13 wt% of an inorganic filler.

[13] The resin syrup used in the transparent chip may preferably comprise an acrylic resin, however, in addition, may comprise polyvinyl chloride (PVC), polystyrene (PS), an epoxy-based resin or an unsaturated polyester (UPE)-based resin. Those resins can be also used in copolymerized form by mixing those resins.

[14] Meanwhile, Japanese Patent Laid-open Publication No. Hei 7-33989 discloses an artificial marble of which transparency is improved by using bromine-containing epoxy acrylate. When a transparent chip is manufactured by using halogenated epoxy acrylate or halogenated urethane acrylate as a resin syrup, it can be ascertained that the transparent chip having the same or similar specific gravity as the matrix with holding transparency can be manufactured. Further, it can be ascertained that when the transparent chip manufactured like this is applied to the present invention, the transparent chip can be more uniformly dispersed within the matrix; even only transparent chip is introduced when not considering the effect of contrasting with the pearl transparent chip, the transparent chip can be uniformly distributed within the matrix since the specific gravity of the transparent chip is the same or similar as that of the matrix; and accordingly the decrease in processibility due to local centering of the transparent chip can be minimized, and simultaneously the sufficient effect of introducing the transparent chip on the outer surface can be obtained even though the transparent chip is not introduced in excessive amounts.

[15] Such transparent chip essentially consists of 70 to 90 wt% of bromine-based epoxy

acrylate or bromine-based urethane acrylate, and comprises 7 to 20 wt% of a crosslinking agent and 1 to 2 wt% of a curing agent, and may comprise a little amount of an inorganic filler.

[16] The acid value of the halogenated epoxy acrylate or halogenated urethane acrylate resin syrup may be 1 to 3.5 DKOH/g. If the acid value exceeds 3.5 DKOH/g, its storage stability becomes bad and its molecular weight becomes small, and thus the hardness, refractive index and flexural strength required in a chip become low and a shrinking phenomenon occurs after manufacturing the chip. If the acid value is less than 1 DKOH/g, its viscosity is too high to apply.

[17] The crosslinking agent applied to the transparent chip includes preferably methacrylate, which is acrylate, for example, ethylene glycol dimethacrylate, propylene glycol dimethacrylate, glycerol trimethacrylate, trimethyl propane trimethacrylate, bisphenol A dimethacrylate or mixtures thereof. However, it could be confirmed that there is no problem in adhesiveness between an acrylate-based matrix and a transparent chip since the major component of transparent chip itself is acrylate, even if non-acrylates, for example, styrene, vinyl toluene, diallyl terephthalate, diallyl phthalate, diallyl carbonate, divinyl benzene, alphamethyl styrene, alphamethyl styrene dimer, polyester denatured vinyl bromide ester resin or mixtures thereof are applied as crosslinking agents.

[18] The ratio of colorants contained in a base and a chip for an artificial marble may be preferably in the order of pearl transparent chip > base > transparent chip in elevating total cubic feel. In general, the cubic feel is expressed by controlling the resin content, however, it was found that the clearness and the cubic feel can be more elevated by controlling the ratio of the colorants as described above. For a semi-transparent chip, it is satisfactory even to maintain the introducing ratio of the colorants in a degree similar to that of the transparent chip.

[19] Meanwhile, an artificial marble according to another characteristic of the present invention further includes 1 to 10 wt% of a semi-transparent chip comprising 50 to 85 wt% of a resin syrup, 5 to 48 wt% of an inorganic filler, 1 to 2 wt% of a crosslinking agent and 1 to 2 wt% of a curing agent. According to such characteristic of the present invention, the effect of contrasting a transparent chip and a pearl transparent chip can be maximized, and the depth feel and cubic feel can be further elevated depending on the transparency difference as shown in FIG. 2.

[20] The ratio of resins between the transparent chip, the semi-transparent chip, the pearl transparent chip and the base is controlled so that it may be in the order of the transparent chip > the semi-transparent chip > the pearl transparent chip > base.

[21] Further, the artificial marble according to the present invention can include below 5 wt% of a solid chip, which is a general opaque chip. Although the solid chip contains

low content of the resin, and thus its transparency is very poor, the contrast effect between the transparent chip and the pearl chip can be further elevated.

[22] The total ratio of the chip for the artificial marble among the total weight % of the artificial marble follows the routine. In general, the total ratio does not exceed 30 wt% of the total weight.

[23]

[24] *Meanwhile, it has been recently increased to apply a natural mineral as a far infrared source in manufacturing an artificial marble in order to provide an artificial marble with health enhancing effect by far infrared. Conventionally, a natural mineral such as zeolite, loess and jade has been applied, however, it can be found that if such mineral is applied, the strength of the artificial marble becomes non-uniform, the mechanical properties such as flexural strength and elastic modulus become deteriorated, and the surface processibility is remarkably deteriorated.

[25] The artificial marble according to the present invention is also characterized in that it further includes a natural mineral comprising 30 to 70 wt% of silica and 30 to 70 wt% of magnesium oxide and having at least 88% of the theoretical value of the far infrared emissivity as a natural mineral applied in order to provide the artificial marble with far infrared emitting effect.

[26] Here, if less than 0.1 wt% of the natural mineral comprising silica and magnesium oxide is added, satisfactory far infrared emissivity effect can be obtained. If the amount of the added natural mineral exceeds 10 wt%, it makes grinding and cutting the artificial marble difficult and also lowers the mechanical elastic strength, and accordingly causes the deterioration in the property of the material and the increase in the production cost.

[27] The natural mineral comprising silica and magnesium oxide is used in the form pulverized in a size of 5 to 100 D. If the natural mineral is added and stirred together with an inorganic filler, the natural mineral is not uniformly distributed within a resin. Therefore, it is preferable to add and stir the natural mineral first prior to other raw material to a resin syrup constituting a base.

Advantageous Effects

[28] According to the artificial marble having the structure described above, the processibility hardly decreases, and the feel of a material inherent in a natural stone such as transparent feel and cubic feel is expressed even though a transparent chip containing high content of a resin component is used. Brief Description of the Drawings

[29] Further objects and advantages of the invention can be more fully understood from the following detailed description taken in conjunction with the accompanying

drawings, in which: [30] FIG. 1 is a mimetic diagram for an artificial marble on which a transparent chip is applied; and [31] FIG. 2 is a mimetic diagram for explaining the structure that cubic feel is expressed by the artificial marble according to the present invention.

Mode for the Invention [32] Hereinafter, each component of the artificial marble according to the present invention and the method of manufacturing the same will be explained in detail. [33] [Base]

[34] The base according to the present invention comprises 20 to 50 wt% of a resin syrup, 25 to 40 wt% of an inorganic filler, 0.05 to 2.5 wt% of a crosslinking agent and

0.05 to 2.5 wt% of a curing agent. [35] As the resin syrup, an acrylic monomer, for example, methyl methacrylate, ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, benzene methacrylate and glycidyl methacrylate, etc., is most preferable. [36] As the inorganic filler, a filler such as calcium carbonate, aluminum hydroxide, silica, alumina, barium lactate and magnesium hydroxide, generally used in preparing an artificial marble, is used, and its size of 1 to 100 Dis proper. [37] As the crosslinking agent, methacrylate having 2 or more functional groups is preferable, and its example includes ethylene glycol dimethacrylate, propylene glycol dimethacrylate, glycerol trimethacrylate, trimethyl propane trimethacrylate or bisphenol A dimethacrylate. [38] As the curing agent (reaction initiator), a peroxide-based reaction initiator usually used in preparing an artificial marble is used, and its example includes benzoyl peroxide, lauroyl peroxide, butyl hydroperoxide, cumyl hydroperoxide or azo compounds. [39] Other additives can be comprised in the amount of 1 to 6 wt%, and their examples include a colorant such as an organic or inorganic pigment, or a functional additive for enhancing the property of material, such as a UV stabilizer, a far infrared emission inducing material and an antibacterial agent. [40] [Transparent chip]

[41] The transparent chip comprises 85 to 98 wt% of a resin syrup, 1 to 20 wt% of a crosslinking agent and 1 to 2 wt% of a curing agent. The transparent chip can further comprise below 13 wt% of an inorganic filler. The total amounts of the transparent chip are preferably about 5 to 25 wt%. [42] As the resin syrup, an acrylic resin is preferable. In addition, polyvinyl chloride

(PVC), polystyrene (PS), an epoxy-based resin, an unsaturated polyester (UPE)-based

resin or a copolymerized form by mixing those resins, etc. can be used. Further, bromine-based epoxy acrylate or bromine-based urethane acrylate, etc. can be also used.

[43] The crosslinking agent applied to the transparent chip is similar as described in the

Base part. However, since transparent chip itself comprises acrylic component as a major component, there is no significant problem in adhesiveness between an acrylate- based matrix and a transparent chip even if a non-acrylic component, for example, styrene, vinyl toluene, diallyl terephthalate, diallyl phthalate, diallyl carbonate, divinyl benzene, alphamethyl styrene, alphamethyl styrene dimer, polyester denatured vinyl bromide ester resin or mixtures thereof are applied as crosslinking agents.

[44] As the inorganic filler, a silica-based filler other than aluminum hydroxide is preferably used for enhancing transparency.

[45] Other components of the material are the same as described in the Base part.

[46] [Semi-transparent chip]

[47] The semi-transparent chip comprises 50 to 85 wt% of a resin syrup, 5 to 48 wt% of an inorganic filler, 1 to 2 wt% of a crosslinking agent and 1 to 2 wt% of a curing agent. The total amounts of the semi-transparent chip are preferably about 1 to 10 wt%.

[48] As the resin syrup, an acrylic resin, a UPE resin, or both can be used.

[49] Other components of the material are the same as described in the Base part, or the usual components can be used.

[50] [Pearl transparent chip]

[51] Pearl transparent chip is a chip in the form of chip-in-chip that is formed by manufacturing the first transparent chip having high content of the resin syrup and high transparency first, then adding the chip in manufacturing the second transparent chip having relatively low content of the resin syrup and simultaneously introducing an artificial pearl, which is formed by metal coating on a natural pearl or mica in order to increase the transparent feel of the first transparent chip by reflection effect. The pearl transparent chip comprises 35 to 50 wt% of a resin syrup, 30 to 43 wt% of an inorganic filler, 0.1 to 5 wt% of a pearl chip, 0.1 to 1 wt% of a crosslinking agent, 0.1 to 1 wt% of a curing agent and 0.1 to 1 wt% of a settling agent; and 1 to 30 wt% of the first transparent chip manufactured by mixing 48 to 78 wt% of a resin syrup, 19 to 48 wt% of an inorganic filler, 1 to 2 wt% of a crosslinking agent, 1 to 2 wt% of a curing agent and 0.1 to 1 wt% of a settling agent, and then curing and grinding the resulting resin slurry. The total amounts of the pearl transparent chip are preferably about 1 to 10 wt%.

[52] As the resin syrup, an acrylic resin is preferably used. As the inorganic filler, the crosslinking agent and the curing agent, the components described previously and the other usual components used in the art for manufacturing an artificial marble can be

used. As the settling agent, the P 104 product available at BYK Company in Germany can be used.

[53] Hereinafter, the specific method of manufacturing the pearl transparent chip will be explained in detail.

[54] Manufacturing the first transparent chip

[55] The first transparent chip is manufactured by mixing 48 to 78 wt% of an acrylic resin syrup comprising 60 to 80% of methyl methacrylate (MMA) and 20 to 40% of polymethyl methacrylate (PMMA), 19 to 48 wt% of an inorganic filler, 1 to 2 wt% of a crosslinking agent, 1 to 2 wt% of a curing agent and 0.1 to 1 wt% of a settling agent, and then curing and grinding the resulting resin slurry.

[56] If the first transparent chip has a size more than 0.8 D, its transparency decreases due to the traces remained in the site impacted during grinding process. In consideration of the relative size relationship between the first chip and the second chip, transparency and yield, a chip in a size of about 0.1 to 3 D is suitable for using as the first transparent chip.

[57] Manufacturing the pearl transparent chip employing the first transparent chip

[58] The pearl transparent chip is manufactured by mixing 35 to 50 wt% of an acrylic resin syrup comprising 60 to 80% of methyl methacrylate and 20 to 40% of polymethyl methacrylate, 30 to 43 wt% of an inorganic filler, 1 to 30 wt% of the first transparent chip, 0.1 to 5 wt% of the pearl chip, 0.1 to 1 wt% of a crosslinking agent, 0.1 to 1 wt% of a curing agent and 0.1 to 1 wt% of a settling agent, and then curing and grinding the resulting resin slurry.

[59] The size of the used pearl transparent chip is preferably 0.1 to 10 D, and more preferably 0.1 to 6 D.

[60] In the above, an artificial pearl in pieces, which a metal (Al or Cu, etc.) is coated on a natural pearl or mica, is used as the pearl chip. When the pearl chip is used, the transparency due to the first transparent chip having highest content of acryl resin syrup, glittering due to the light reflected by a pearl, and depth feel expressed by which the light passed through the first transparent chip is reflected by a rear pearl, are all achieved as shown in FIG. 2.

[61] Such pearl chip is added in the amount of 0.1 to 5 wt% among the total weight. If the pearl chip more than 5 wt% is added, it makes grinding and cutting the artificial marble very difficult. If the pearl chip less than 0.1 wt% is added, glittering peculiar to pearl is not expressed well on the manufactured artificial marble. The size of the used pearl chip is preferably about 200 to 1200 D.

[62] Meanwhile, the color of the first transparent chip is preferably the same series as the color of the pearl transparent chip in elevating the transparency of the first transparent chip. By an example, the pearl transparent chip has black series color. If the first

transparent chip has white series color, the transparency of the first transparent chip is apparently decreased. [63] [Solid chip]

[64] The solid chip comprises 30 to 35 wt% of a resin syrup, 35 to 68 wt% of an inorganic filler, 1 to 2 wt% of a cros slinking agent and 1 to 2 wt% of a curing agent.

The total amounts of the solid chip are preferably below about 5 wt%. [65] As the resin, both a UPE resin and an acrylic resin can be used, and the components of the other material are the same as described previously, or the usual components can be used.

Industrial Applicability [66] The present invention relates to an artificial marble having transparent feel and cubic feel, of which processibility hardly decreases even though the transparent chip having high content of a resin component is used.

[67] Although the present invention has been described with reference to several embodiments of the invention, the description is illustrative of the invention and is not to be construed as limiting the invention. Various modifications and variations may occur to those skilled in the art, without departing from the spirit and scope of the invention as defined by the appended claims.