ARTIFICIAL STONE

Abstract

An artificial stone and a curable composition for manufacturing the artificial stone are provided. The curable composition is capable of manufacturing an artificial stone that has excellent optical properties, is free to show color and the like, has excellent physical properties such as scratch resistance, and also has remarkable light resistance. The curable composition has formability and physical properties that are suitable for being formed into artificial stone.

Claims

1. Artificial stone which is a cured product of a curable composition comprising: a polyol component; an isocyanate component comprising a bifunctional non-aromatic isocyanate compound and a multifunctional non-aromatic isocyanate compound having trifunctionality or more; and a filler.

2. The artificial stone according to claim 1, wherein the polyol component comprises 80 mol % or more of a polyol having a molecular weight of 500 g/mol or less.

3. The artificial stone according to claim 1, wherein the polyol component comprises 80 mol % or more of a non-aromatic polyol.

4. The artificial stone according to claim 3, wherein the non-aromatic polyol is a non-aromatic acyclic polyol.

5. The artificial stone according to claim 1, wherein the polyol component comprises a bifunctional polyol and a multifunctional polyol having trifunctionality or more.

6. The artificial stone according to claim 5, wherein the polyol component comprises 25 to 55 mol % of the bifunctional polyol.

7. The artificial stone according to claim 5, wherein the ratio (P2/PM) of the mole number (P2) of the bifunctional polyol to the mole number (PM) of the multifunctional polyol in the curable composition is in a range of 0.2 to 1.5.

8. The artificial stone according to claim 1, wherein the isocyanate component comprises 80 mol % or more of an isocyanate compound having a molecular weight of 1,000 g/mol or less.

9. The artificial stone according to claim 1, wherein the isocyanate component comprises 80 mol % or more of a non-aromatic isocyanate compound.

10. The artificial stone according to claim 1, wherein the bifunctional non-aromatic polyol is represented by the following formula 1: ##STR00002## wherein, L.sub.1 to L.sub.4 are each independently a single bond or a linear or branched alkylene group having 1 to 20 carbon atoms.

11. The artificial stone according to claim 1, wherein the isocyanate component comprises 55 to 90 mol % of the bifunctional non-aromatic isocyanate compound.

12. The artificial stone according to claim 1, wherein the ratio (N2/NM) of the mole number (N2) of the bifunctional non-aromatic isocyanate compound to the mole number (NM) of the multifunctional non-aromatic isocyanate compound in the curable composition is in a range of 1.5 to 5.

13. The artificial stone according to claim 1, wherein in the curable composition, the ratio (P/N) of the mole number (P) of the polyol compound in the polyol component to the mole number (N) of the isocyanate compound in the isocyanate component is in a range of 0.4 to 1.5.

14. The artificial stone according to claim 1, wherein in the curable composition, the ratio (OH/NCO) of the mole number (OH) of the total hydroxyl groups in the polyol component to the mole number (NCO) of the total isocyanate groups in the isocyanate component is in a range of 0.8 to 1.2.

15. The artificial stone according to claim 1, wherein the filler is a quartz-based filler.

16. The artificial stone according to claim 1, wherein the curable composition comprises the filler in a ratio of 70 to 95 wt %.

17. The artificial stone according to claim 1, wherein the total weight part of the polyol component and the isocyanate component in the curable composition is in a range of 5 to 30 parts by weight relative to 100 parts by weight of the filler.

18. The artificial stone according to claim 1, wherein Ab* in the following equation 4 is in a range of −1.5 to 3:
Δb*=ba*−bi*  [Equation 4] wherein, ba* is the b* value of the artificial stone in the CIE Lab color coordinates immediately after being exposed to ultraviolet rays for 1000 hours, and bi* is the b* value of the artificial stone in the CIE Lab color coordinates immediately before exposure to the ultraviolet rays for 1000 hours.

19. The artificial stone according to claim 1, wherein the absolute value of the change amount ΔE of the color change index before and after exposure to ultraviolet rays for 1000 hours is 3 or less.

20. Artificial stone which is a cured product of a curable composition comprising: a polyol component; an isocyanate component comprising a bifunctional non-aromatic isocyanate compound and a multifunctional non-aromatic isocyanate compound having trifunctionality or more; and a filler.

Description

DESCRIPTION OF DRAWINGS

[0095] FIGS. 1 and 2 are images of artificial stone manufactured with the curable composition of Example 1 immediately before and immediately after being exposed to ultraviolet rays for 1000 hours, respectively.

[0096] FIGS. 3 and 4 are images of artificial stone manufactured with the curable composition of Comparative Example 1 immediately before and immediately after being exposed to ultraviolet rays for 1000 hours, respectively.

[0097] FIGS. 5 and 6 are images of artificial stone manufactured with the curable composition of Comparative Example 2 immediately before and immediately after being exposed to ultraviolet rays for 1000 hours, respectively.

BEST MODE

[0098] Hereinafter, the present application will be described in detail through Examples, but the scope of the present application is not limited by Examples below.

[0099] 1. Formability Evaluation

[0100] The curable compositions prepared in Examples or Comparative Examples are each introduced into a mold for artificial stone, and molded into a plate shape by applying compression while vibrating the upper plate of the mold for 1 minute and 30 seconds using a vibrator under a vacuum condition. Subsequently, the molded material was heat-cured with a top and bottom hot-press oven, in which the top and bottom plates were each set at a temperature of 120° C., for 1 hour. After curing is completed, the cured product is cooled to room temperature, taken out from the mold, and then cut in all directions, and surface-polished to manufacture artificial stone. When the artificial stone is stably manufactured through such a process, the formability is evaluated as PASS, and when the artificial stone cannot be manufactured for reasons such as phase separation and high or low viscosity, it is evaluated as NG.

[0101] 2. Transparency Evaluation

[0102] The binders (mixtures of resin components before mixing with a quartz-based filler) prepared in Examples or Comparative Examples are each maintained at a temperature of 120° C. for 1 hour or so and cured, thereby forming a plate-shaped cured product having a thickness of 5 mm or so. Subsequently, using a CM-5 spectrophotometer (Konica minolta) and a D65 standard light source, transmittance (transparency), and b* values of CIE Lab color coordinates of transmitted light are evaluated. The meaning of the b* value is the same as in the text.

[0103] 3. Evaluation of Scratch Resistance

[0104] Scratch resistance was evaluated through the Erichsen test on the plate-shaped cured product formed in the same manner as in the transparency evaluation.

[0105] The Erichsen test is a surface strength test performed using Erichsen's scratch hardness tester 413, where it is evaluated as PASS in the case of satisfying a value of 1.4N (the standard value) or more, and it is evaluated as NG in the case of less than 1.4N. In the test method, a specimen is fixed on the tester, and then the weight is increased by 0.1N from 0 using diamond tips and weights, and it is confirmed whether scratches are generated on the surface. The weight at the time when the scratches are visible is weighed.

[0106] 4. Light Durability Evaluation

[0107] The curable compositions of Examples or Comparative Examples are each applied to the method in the above formability evaluation to manufacture artificial stone. Using QUV equipment (QUV, Q-LAB), the manufactured artificial stone has been exposed to ultraviolet rays with a wavelength of 340 nm at an intensity of 0.6 W/m.sup.2, where the temperature inside the equipment is maintained at 50° C.

[0108] Using a CIE LAB colorimeter (Spectro-guide, BYK), L*, a* and b* values of the CIE Lab color space are each measured. The definitions of the L*, a* and b* values are the same as in the text. The L*, a*, and b* values before and after ultraviolet exposure are obtained, respectively, and ΔL*, Δa* and Δb* values are obtained, respectively, through the difference between the values before and after ultraviolet exposure.

[0109] Thereafter, the color change value ΔE can be obtained by substituting the obtained values into Equation A below.

ΔE=(ΔL*.sup.2+Δa*.sup.2+Δb*.sup.2).sup.1/2  [Formula A]

Example 1

[0110] 37 wt % of hydrogenated xylene diisocyanate (Takenate-600, Mitsui Chemical) (molecular weight: about 194.24 g/mol), 36 wt % of an HDI isocyanurate trimer (hexamethylene diisocyanate isocyanurate trimer, Desmodur N3300, Covestro) (molecular weight: about 504.6 g/mol), 17 wt % of trimethylolpropane (molecular weight: about 134.17 g/mol), 9 wt % of diethylene glycol (molecular weight: about 106.12 g/mol) and 1 wt % of a tertiary amine (1-methylimidazole) were mixed at room temperature to prepare a mixture (binder).

[0111] As a filler, a quartz-based filler was prepared. The quartz-based filler was prepared by mixing 41 wt % of quartz sand having an average particle size of about 0.1 mm to 0.3 mm, 19 wt % of quartz sand having an average particle size of about 0.3 mm to 0.7 mm, and 29 wt % of quartz powder having an average particle size of about 325 mesh.

[0112] A curable composition was prepared by uniformly mixing the binder and the quartz-based filler in a weight ratio of 89:11 (binder: quartz-based filler).

Example 2

[0113] A curable composition was prepared in the same manner as in Example 1, except that isophorone diisocyanate (IPDI) (molecular weight: about 222.3 g/mol) was used instead of hydrogenated xylene diisocyanate when preparing the binder.

Example 3

[0114] A curable composition was prepared in the same manner as in Example 1, except that hexamethylene diisocyanate biuret (HDI biuret) (Covestro's Desmodur N3200) (molecular weight: 478.59 g/mol) was used instead of HDI isocyanurate when preparing the binder.

Comparative Example 1

[0115] A curable composition was prepared in the same manner as in Example 1, except that a general unsaturated polyester for E-stone (engineered stone) was used as the binder.

Comparative Example 2

[0116] A curable composition was prepared in the same manner as in Example 1, except that a bio resin in the form of a mixture, in which 55 wt % of epoxidized linseed oil (Arkema), 41 wt % of a hexahydro-4-methylphthalic anhydride curing agent (Aldrich) and 4 wt % of a polyol solution dissolved by 1-methylimidazole were mixed at room temperature, was used as the binder.

Comparative Example 3

[0117] A curable composition was prepared in the same manner as in Example 1, except that hydrogenated xylene diisocyanate was not used when preparing the binder and the amount of HDI isocyanurate was 74 wt %.

Comparative Example 4

[0118] A curable composition was prepared in the same manner as in Example 1, except that HDI isocyanurate was not used when preparing the binder and the amount of hydrogenated xylene diisocyanate was 74 wt %.

[0119] The relationships such as the mole numbers of the bifunctional polyol (diethylene glycol), multifunctional polyol (trimethylolpropane), bifunctional isocyanate compound (hydrogenated xylene diisocyanate, isophorone diisocyanate) and trifunctional isocyanate compound (HDI isocyanurate, HDI biuret) applied in each of Examples 1 to 3 and Comparative Examples 3 to 6 were summarized and described in Table 1 below.

TABLE-US-00001 TABLE 1 Example Comparative Example 1 2 3 3 4 Polyol DEG 0.08 0.08 0.08 0.08 0.08 TMP 0.13 0.13 0.13 0.13 0.13 NCO HXDN 0.19 0 0.19 0 0.38 compound IPDI 0 0.17 0 0 0 HDII 0.07 0.07 0 0.14 0 HDIB 0 0 0.08 0 0 OH/NCO 0.92 1.01 0.91 1.27 0.73 P2/PM 0.67 0.67 0.67 0.67 0.67 N2/NM 2.67 2.33 2.53 0 — P/N 0.81 0.89 0.8 1.46 0.56 NCO compound: isocyanate compound; DEG: mole number ratio of diethylene glycol in the binder; TMP: mole number ratio of trimethylolpropane in the binder; HXDN: mole number ratio of hydrogenated xylene diisocyanate in the binder; IPDI: mole number ratio of isophorone diisocyanate in the binder; HDII: mole number ratio of HDI isocyanurate in the binder; HDIB: mole number ratio of HDI burette in the binder; OH/NCO: molar ratio of the total hydroxyl groups in the polyol component to the total isocyanate groups in the NCO compound; P2/PM: ratio of the mole number of the bifunctional polyol to the mole number of the multifunctional polyol; N2/NM: ratio of the mole number of the bifunctional NCO compound to the mole number of the multifunctional NCO compound; P/N: ratio of the mole number of polyol to the mole number of NCO compound

[0120] Evaluation results for the curable compositions of Examples and Comparative Examples above were summarized and described in Tables 2 and 3 below. However, in the case of Comparative Examples 3 and 4, the artificial stone was not properly manufactured for the reasons such as phase separation, high viscosity, low viscosity or low hardness, whereby the formability became NG, so that other physical properties could not be evaluated.

TABLE-US-00002 TABLE 2 Example 1 2 3 Formability PASS PASS PASS Transmittance (%) 91.2 90.4 89.1 b* of CIE Lab color space 0.57 1.21 1.42 Scratch resistance PASS PASS PASS

TABLE-US-00003 TABLE 3 Comparative Example 1 2 3 4 Formability PASS PASS NG NG Transmittance (%) 87.9 89.8 — — b* of CIE Lab color space −0.05 4.5 — — Scratch resistance PASS PASS — —

[0121] Light durability evaluation results for the curable compositions of Examples and Comparative Examples above were summarized and described in Table 4 below. However, in the case of Comparative Examples 3 and 4, the artificial stone was not properly manufactured for the reasons such as phase separation, high viscosity, low viscosity or low hardness, whereby the formability became NG, so that other physical properties could not be evaluated.

TABLE-US-00004 TABLE 4 Example Comparative Example 1 2 3 1 2 CIE Lab characteristics L* 91.07 80.28 78.65 89.78 88.31 immediately before exposure to a* 0 −0.11 −0.08 −0.15 −0.15 ultraviolet rays for 1000 hours b* 2.42 2.32 3.33 3.85 6.91 CIE Lab characteristics L* 91.41 80.22 80.09 88.55 92.14 immediately after exposure to a* −0.40 −0.55 −0.47 −1.11 −0.26 ultraviolet rays for 1000 hours b* 3.49 3.87 5.24 19.61 5.16 ΔE 1.19 1.61 2.42 15.84 4.21 Δb* 1.07 1.55 1.91 15.76 −1.75

[0122] From Table 4, it can be confirmed that the artificial stone manufactured with the curable compositions of Examples in its initial state exhibits the larger L* value compared to Comparative Examples, resulting in the brighter color and simultaneously exhibits the color closer to white through the lower b* value. In addition, it can be confirmed that color change and yellowing are suppressed even after exposure to ultraviolet rays. FIG. 1 is an image of artificial stone manufactured with the curable composition of Example 1 before ultraviolet exposure and FIG. 2 is an image of the artificial stone after exposure to ultraviolet rays for 1000 hours; FIG. 3 is an image of artificial stone manufactured with the curable composition of Comparative Example 1 before ultraviolet exposure and FIG. 4 is an image of the artificial stone after exposure to ultraviolet rays for 1000 hours; and FIG. 5 is an image of artificial stone manufactured with the curable composition of Comparative Example 2 before ultraviolet exposure and FIG. 6 is an image of the artificial stone after exposure to ultraviolet rays for 1000 hours.