JPH0667610B2 - Artificial marble - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to improvement of artificial marble used for kitchen counters, wash counters, wash balls, table tops, and the like.

(Prior Art) Conventional artificial marble has a mold or resin mold coated with a release agent such as poval or wax, and further an unsaturated polyester resin with a hardening agent added by spraying 250-500 microns It is applied to a thickness of about 50% and cured by natural or forced drying. Inside the surface layer, a thermosetting resin such as unsaturated polyester resin is filled with calcium carbonate or the like, a filler, a curing agent, and a curing accelerator. A base layer is formed by pouring a material to which the above components have been added and cured to form a surface layer on the surface of the base layer. This surface layer is intended to sufficiently improve the surface hardness, smoothness, transparency and glossiness and to prevent stains.

(Problems to be Solved by the Invention) However, the conventional surface layer has a pencil hardness of about H to 2H and is easily scratched by a hard foreign substance, which impairs the aesthetics and has a sufficient purpose as a surface layer. In particular, it was insufficient in terms of hardness that it could not be achieved.

Therefore, it is desired to increase the hardness of the surface layer. Artificial marble that has a higher cross-linking density than the unsaturated polyester resin used for conventional surface layers and has a hardness after curing that is mainly composed of unsaturated polyester resin is considered to be provided on the surface of the base layer. . In this case, it can be seen that the surface layer has a pencil hardness of about 4H to 8H, the hardness is certainly high, and scratches are unlikely to occur even with hard foreign matter. However, the unsaturated polyester resin of the surface layer has a higher crosslink density and higher reactivity than conventional ones, so the unsaturated polyester resin of the surface layer is applied to the mold by spraying, etc., and the base layer is poured after heat curing and molding. At times, the surface layer may be hardened, and the adhesion between the surface layer and the base layer may deteriorate. In this case, the surface layer may peel off from the base layer especially when cooled due to the difference in the coefficient of thermal expansion between the base layer and the surface layer. Further, when the base layer and the surface layer are in close contact with each other, since the filler such as calcium carbonate is present in the base layer as described above, the coefficient of thermal expansion is much smaller than that of the surface layer. The unsaturated polyester resin having a high cross-link density and a relatively high hardness of the surface layer has a low cross-link density and is less flexible than the unsaturated polyester resin having a relatively low hardness. When the base layer is cooled and contracts, stress concentration occurs between the base layer and the filler existing on the surface of the base layer, and a crack is generated from this portion. Further, since the surface layer has high reactivity, it is difficult to manufacture.

The present invention has been made based on the above circumstances, and an object of the present invention is to provide an artificial marble having a large surface hardness without the conventional problems.

(Means and Actions for Solving Problems) In order to solve the above problems, the present invention provides a thermosetting resin such as an unsaturated polyester resin and a surface of a base layer containing a filler such as calcium carbonate as a main raw material. , A lower surface layer containing an unsaturated polyester resin as a main raw material is provided, and an unsaturated polyester resin having a higher cross-linking density and a higher hardness than the unsaturated polyester resin of the lower surface layer is mainly provided on the upper surface of the lower surface layer. An upper surface layer as a raw material was provided, and the upper surface layer was formed to be harder than the lower surface layer.

Therefore, since the hardness of the upper surface layer is increased, the surface hardness of the artificial marble is increased and the hard foreign matter is less likely to be scratched. Since there is a lower surface layer between the upper surface layer and the base layer, which has a higher hardness and has a lower cross-linking density and a lower hardness than the upper surface layer, it repeatedly expands and contracts by being cooled after being warmed during use. However, stress concentration does not occur between the filler of the base layer and the lower surface layer, and cracks do not occur. Further, peeling does not occur between the base layer and the lower surface layer.

(Examples) Examples of the present invention will be described below with reference to the drawings. The artificial marble 1 is a base layer formed by curing an unsaturated polyester resin, which is a thermosetting resin, as a main raw material, a filler such as calcium carbonate, aluminum hydroxide, cold water, etc., with an application agent, a curing agent, a curing accelerator, etc. 2 and 20 on the surface of the base layer 2
The lower surface layer 3 is formed to have a thickness of about 0 to 300 μm, and is formed by adding a curing agent or the like to an unsaturated polyester resin as a main material and curing the same, and 50 to 20 on the upper surface of the lower surface layer 3.
The upper surface layer 4 is formed to have a thickness of about 0 micron and is formed by curing an unsaturated polyester resin having a higher cross-linking density than the unsaturated polyester resin of the lower surface layer 3 by adding a curing agent or the like and curing the unsaturated polyester resin. Has been done.

For the lower surface layer 3, an unsaturated polyester resin having a relatively small cross-linking density and having a hardness after curing of about H to 3H in pencil hardness is used, and for the upper surface layer 4, as described above, An unsaturated polyester resin having a crosslinking density higher than that of the unsaturated polyester resin of the lower surface layer 3 and having a hardness after curing of about 4H to 8H in pencil hardness is used.

According to the artificial marble 1 having the above structure, however, the upper surface layer 4 has a hardness higher than that of the conventional surface layer, so that it is less likely to be scratched by a hard foreign matter, and the surface hardness, smoothness,
The transparency and gloss are sufficiently good, and the heat resistance and detergent resistance are further improved. Further, the unsaturated polyester resin of the lower surface layer 3 has a smaller cross-linking density than the unsaturated polyester resin of the upper surface layer 4, and therefore has relatively low reactivity, and thus is easy to manufacture. Therefore, when the base layer 2 is formed on the back surface of the lower surface layer 3 after the lower surface layer 3 is formed and cured, the lower surface layer 3 is cured to some extent, but the base layer 2 is formed before the curing is completed. Therefore, the lower surface layer 3 and the base layer 2 strongly adhere to each other. Therefore, even when it is warmed and cooled during use, the lower surface layer 3 does not peel off from the base layer 2 because it adheres strongly. Further, the lower surface layer 3 and the upper surface layer 4 have a much higher expansion coefficient than the base layer 2 in which the filler is present, but during use, artificial marble that has been warmed during the daytime is cooled at night. At this time, even if the lower surface layer 3 and the upper surface layer 4 contract, the lower surface layer 3 is relatively flexible, so that stress is dispersed between the lower surface layer 3 and the filler of the base layer 2 to reduce stress concentration. Since it does not shrink, it does not crack from this part. At this time, the upper surface layer 4 strongly adheres to the lower surface layer 3, and further, in terms of expansion coefficient,
The upper surface layer 4 is much larger than the base layer 2, but is slightly smaller than the lower surface layer 3, so that the lower surface layer 3
No peeling or cracking occurs between the upper surface layer 4 and the upper surface layer 4.

As described above, the lower surface layer 3 is formed to have a thickness of about 200 to 300 microns and the upper surface layer is formed to have a thickness of about 50 to 200 microns. Four
The total thickness of and should be about 250 to 500 microns. For example, when the lower surface layer is formed to a thickness of about 200 microns, the upper surface layer 4 is formed to a thickness between 50 and 300 microns, and the lower surface layer 3 is formed to a thickness of 300 microns. It is better in terms of price and manufacturing that the upper surface layer 4 is formed with a thickness of about 200 μm and the lower surface layer 3 is formed thicker than the upper surface layer 4.

Although the unsaturated polyester resin has been described as the thermosetting resin of the base layer 2 in the above-described embodiment, the present invention is not limited to this, and an acrylic resin or an epoxy resin may be used.
In addition, in the above-mentioned embodiment, the hardness of the upper surface layer 4 is 4H in terms of pencil hardness.
Although it has been described as about 8H, about 5H to 7H is optimal, and if it is 8H or more, it is too hard and cracks easily occur when it is heated or cooled.

(Effects of the Invention) As described above, the present invention is, in artificial marble, a lower surface layer containing an unsaturated polyester resin as a main material on the surface of a base layer containing a thermosetting resin and a filler as main materials. On the upper surface of the lower surface layer, an unsaturated polyester resin having a higher crosslinking density than the unsaturated polyester resin of the lower surface layer is used as a main raw material, and an upper surface layer having a hardness higher than that of the lower surface layer is formed. I decided to provide it. Therefore, especially in winter, even when artificial marble heated in the daytime is cooled at night and repeatedly expanded and contracted, the surface layer does not peel off from the base layer or crack. Further, since the surface hardness can be made sufficiently larger than that of the conventional one, the artificial marble is less likely to be scratched by a hard foreign matter, and the aesthetic appearance is not impaired. Furthermore, since the heat resistance is improved, there is no whitening or yellowing due to heat. Further, there are advantages such as easy manufacture.

[Brief description of drawings]

 The drawings are embodiments of the present invention. 1 ... Artificial marble 2 ... Base layer 3 ... Lower surface layer 4 ... Upper surface layer

Claims (1)

[Claims] 1. A base layer containing at least a thermosetting resin and a filler as main raw materials, a lower surface layer provided on the surface of the base layer and containing an unsaturated polyester resin as a main raw material, and the lower surface layer. And an upper surface layer having a hardness higher than that of the lower surface layer, which is mainly composed of an unsaturated polyester resin having a higher crosslinking density than the unsaturated polyester resin of the lower surface layer. Artificial marble characterized by that.