CRACKS-CONTROLLABLE COATING AND PREPARATION METHOD THEREOF

Abstract

A method of preparing a crack-controllable coating layer includes the following steps. (1) A colored reaction-curable primer is sprayed on a substrate, and dried to form a first primer layer. (2) A white one-component crackle coating is sprayed on the first primer layer, and dried to form a first crackle coating layer. (3) One or two coats of a transparent reaction-curable primer are sprayed on the first crackle coating layer and dried to form a second primer layer. (4) A transparent one-component crackle coating is sprayed, and dried to form a second crackle coating layer. (5) A colorant is spread on a surface of the second crackle coating layer to fill a crack in the second crackle coating layer, and the excess colorant is wiped, and then the second crackle coating layer is dried. A polyurethane varnish is sprayed and dried to obtain the crack-controllable coating layer.

Claims

1. A method of preparing a crack-controllable coating, comprising: (1) spraying at least one coat of a colored reaction-curable primer on a substrate followed by drying to form a first primer layer; (2) spraying a first one-component crackle coating on the first primer layer followed by drying to form a first crackle coating layer; (3) spraying one or two coats of a transparent reaction-curable primer on the first crackle coating layer followed by drying to form a second primer layer; (4) spraying a second one-component crackle coating on the second primer layer followed by drying to form a second crackle coating layer, wherein the second one-component crackle coating is transparent; and (5) spreading a colorant on a surface of the second crackle coating layer to allow the colorant to be embedded in a crack in the second crackle coating layer; wiping the second crackle coating layer to remove excess colorant followed by drying; and spraying a polyurethane varnish on the second crackle coating layer followed by drying to obtain the crack-controllable coating; wherein in the step (2), a spraying amount of the first one-component crackle coating is 6-8 m.sup.2/kg; a thickness of the first crackle coating layer is 30-40 ?m; the drying is performed to allow hard drying of the first one-component crackle coating; and the first one-component crackle coating comprises a white one-component crackle coating, and the white one-component crackle coating is a white nitro crackle lacquer, a white acrylic crackle lacquer or a combination thereof; in the step (4), a spraying amount of the second one-component crackle coating is 12-15 m.sup.2/kg; a thickness of the second crackle coating layer is 15-25 ?m; the drying is performed to allow hard drying of the second one-component crackle coating; and the second one-component crackle coating comprises a transparent one-component crackle coating, and the transparent one-component crackle coating is a transparent nitro crackle lacquer, a transparent acrylic crackle coating or a combination thereof; the step (1) further comprises: testing a surface drying time and a hard drying time of the colored reaction-curable primer; wherein the drying is performed at 5-35? C. and a humidity of 30%-75%, and a drying time is 1.5-2.5 times the surface drying time of the colored reaction-curable primer and 35%-45% of the hard drying time of the colored reaction-curable primer; and the step (3) further comprises: testing a surface drying time and a hard drying time of the transparent reaction-curable primer; wherein the drying is performed at 5-35? C. and a humidity of 30%-75%, and a drying time is 1.5-2.5 times of the surface drying time of the transparent reaction-curable primer and 35%-45% of the hard drying time of the transparent reaction-curable primer.

2. The method of claim 1, wherein in the step (1), the colored reaction-curable primer comprises a black reaction-curable primer.

3. The method of claim 2, wherein the black reaction-curable primer is selected from the group consisting of a black two-component polyurethane primer, a black one-component moisture-curable polyurethane primer, a black one-component alkyd enamel, a black two-component epoxy primer and a combination thereof.

4. The method of claim 1, wherein the substrate is made of bamboo wood, concrete, metal or a combination thereof.

5. The method of claim 1, wherein the first crackle coating layer is presented in ice crackles with a width of 0.3-0.8 mm.

6. The method of claim 1, wherein a crack of the first crackle coating layer presents a color of the first primer layer.

7. The method of claim 1, wherein in the step (3), the transparent reaction-curable primer is selected from the group consisting of a transparent two-component polyurethane primer, a transparent one-component moisture-curable polyurethane primer, a transparent one-component alkyd primer, a transparent two-component epoxy primer and a combination thereof.

8. The method of claim 1, wherein the second crackle coating layer is presented in fish seed crackles with a width of 0.05-0.2 mm.

9. The method of claim 1, wherein in the step (5), the colorant comprises a yellow colorant.

10. The method of claim 9, wherein the yellow colorant is a yellow oily metal complex dye, a yellow iron oxide Anba glaze or a combination thereof.

11. The method of claim 1, wherein the polyurethane varnish comprises a two-component polyurethane varnish.

12. A crack-controllable coating, wherein the crack-controllable coating is prepared by the method of claim 1; the crack-controllable coating has the same golden thread and iron wire effect as a Ge kiln porcelain.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0065] FIG. 1a is a schematic diagram of a morphology of a controllable fine crack coating according to one embodiment of the present disclosure;

[0066] FIG. 1b is a schematic diagram of a morphology of an uncontrollable crack coating according to one embodiment of the present disclosure; and

[0067] FIG. 2 is a schematic diagram of a morphology of a crack-controllable coating obtained in Example 1 of the present disclosure.

DETAILED DESCRIPTION OF EMBODIMENTS

[0068] Embodiments are described below to facilitate the understanding of the present disclosure and not intended to limit the disclosure.

Example 1

[0069] This example provides a crack-controllable coating, the morphology of which is schematically shown in FIG. 2. The crack-controllable coating is prepared by the following steps.

[0070] (1) Black odorless polyurethane primer was sprayed on the surface of treated wood furniture and dried. The surface drying time of the polyurethane primer was 13 minutes, and the hard drying time was 2.5 h. The polyurethane primer was self-dried at 25? C. and a humidity of 55% for 30 minutes to form a first primer layer. The black odorless polyurethane primer was purchased from Bauhinia Coatings Manufacturing (Shanghai) Co., Ltd, and product model: ZJP4310-10398N.

[0071] (2) According to a spraying amount of 7 m.sup.2/kg with an error within 0.5 m.sup.2/kg, and white nitro crackle lacquer was sprayed on the first primer layer. After tens of seconds, there were large cracks with the average width of 0.7 mm, and width fluctuations were in the range of 0.05 mm. The cracks were black. After 12 hours of hard drying, the first crackle coating layer was formed. The white nitro crackle lacquer was purchased from Bauhinia, and product model: 691-01A.

[0072] (3) Transparent odorless polyurethane primer was sprayed on the first crackle coating layer. The surface drying time of the transparent odorless polyurethane primer was 15 minutes, and the hard drying time was 2.5 hours. The transparent odorless polyurethane primer was dried at 25? C. and a humidity of 55% for 30 minutes, so as to form a second primer layer. The transparent odorless polyurethane primer was purchased from Bauhinia, and product model: ZJP3312N.

[0073] (4) According to a spraying amount of 13 m.sup.2/kg with the error within 0.5 m.sup.2/kg, transparent nitro crackle varnish was sprayed on the second primer layer. After tens of seconds, there were fine cracks with the cracking width of 0.1 mm, and the width fluctuations were in the range of 0.02 mm. After 4 hours of hard drying, a second crackle coating layer was formed. The transparent nitro crackle varnish was purchased from Bauhinia, and product model: LW-99.

[0074] (5) Cotton cloth dipped in high concentration of yellow essence and wiped the surface of the second crackle coating layer. The small cracks were filled with yellow essence, and excess essence was cleaned up. Then, a high yellowing-resistant polyurethane varnish was sprayed and dried, to obtain the crack-controllable coating with the imitation effect of the kiln golden thread. The yellow essence was purchased from Bauhinia, and product model: 694-002. The high yellowing-resistant polyurethane varnish was purchased from Bauhinia, and product model: ZJP6697F7.

Example 2

[0075] A crack-controllable coating was prepared by the following method.

[0076] (1) Black moisture-curable polyurethane primer was sprayed on the surface of treated bamboo furniture. The surface drying time of the polyurethane primer was 15 minutes, and the hard drying time was 4 hours and 10 minutes. The polyurethane primer was self-dried at 25? C. and a humidity of 55% for 40 minutes to form a first primer layer. The black moisture-curable polyurethane primer was purchased from Bauhinia, and product model: D899-88.

[0077] (2) According to a spraying amount of 7.5 m.sup.2/kg with an error within 0.5 m.sup.2/kg, and white nitro crackle lacquer was sprayed on the first primer layer. After tens of seconds, there were large cracks with the average width of 0.6 mm, and width fluctuations were in the range of 0.05 mm. The cracks were black. After 12 hours of hard drying, the first crackle coating layer was formed. The white nitro crackle lacquer was purchased from Bauhinia, and product model: 691-01A.

[0078] (3) Moisture-curable polyurethane varnish was sprayed on the first crackle coating layer. The surface drying time of the moisture-curable polyurethane varnish was 15 minutes, and the hard drying time was 4 hours. The moisture-curable polyurethane varnish was dried at 25? C. and a humidity of 55% for 30 minutes, so as to form a second primer layer. The moisture-curable polyurethane varnish was purchased from Bauhinia, and product model: D899.

[0079] (4) According to a spraying amount of 13.5 m.sup.2/kg with the error within 0.5 m.sup.2/kg, transparent nitro crackle varnish was sprayed on the second primer layer. After tens of seconds, there were fine cracks with the cracking width of 0.1 mm, and the width fluctuations were in the range of 0.02 mm. After 4 hours of hard drying, a second crackle coating layer was formed. The transparent nitro crackle varnish was purchased from Bauhinia, and product model: LW-99.

[0080] (5) Cotton cloth dipped with yellow iron oxide (Glaze) was used to wipe the surface of the second crackle coating layer. The small cracks were filled with yellow iron oxide, and excess iron oxide was cleaned up. Then, a high yellowing-resistant polyurethane varnish was sprayed and dried, to obtain the crack-controllable coating with the imitation effect of the kiln golden thread. The yellow iron oxide was purchased from Bauhinia, and product model: ZJCB32A. The yellowing-resistant polyurethane varnish was purchased from Bauhinia, and product model: ZJP6697F7.

Example 3

[0081] A crack-controllable coating was prepared by the following method.

[0082] (1) Black alkyd enamel was sprayed on the surface of a treated concrete wall. The surface drying time of the black alkyd enamel was 40 minutes, and the hard drying time was 5 hours. The black alkyd enamel was self-dried at 25? C. and the humidity of 55% for 1 hour to form a first primer layer. The black alkyd enamel was purchased from Bauhinia, and product model: Zipc10T-88.

[0083] (2) According to an average spraying amount of 7.5 m.sup.2/kg with an error within 0.5 m.sup.2/kg, and white waterborne acrylic crackle lacquer was sprayed on the first primer layer. After tens of seconds, there were large cracks with the average width of 0.5 mm, and width fluctuations were in the range of 0.05 mm. The cracks were black. After 24 hours of hard drying, the first crackle coating layer was formed. The white waterborne acrylic crackle lacquer was purchased from Bauhinia, and product model: ZJW4320F0.

[0084] (3) Alkyd varnish was sprayed on the first crackle coating layer. The surface drying time of the alkyd varnish was 40 minutes, and the hard drying time was 5 hours. The alkyd varnish was dried at 25? C. and a humidity of 55% for 1 hour, so as to form a second primer layer. The alkyd varnish was purchased from Bauhinia, and product model: Zipc10T-99.

[0085] (4) According to a spraying amount of 14.5 m.sup.2/kg with the error within 0.5 m.sup.2/kg, waterborne acrylic crackle varnish was sprayed on the second primer layer. After tens of seconds, there were fine cracks with the cracking width of 0.1 mm, and the width fluctuations were in the range of 0.02 mm. After 12 hours of hard drying, a second crackle coating layer was formed. The waterborne acrylic crackle varnish was purchased from Bauhinia, and product model: ZJW4329.

[0086] (5) Cotton cloth dipped yellow iron oxide and wiped the surface of the second crackle coating layer. The small cracks were filled with yellow iron oxide, and excess iron oxide was cleaned up. Then, a high yellowing-resistant polyurethane varnish was sprayed and dried, to obtain the crack-controllable coating with the imitation effect of the kiln golden thread. The yellow iron oxide was purchased from Bauhinia Advance Materials Group (product model: ZJCB32A). The yellowing-resistant polyurethane varnish was purchased from Bauhinia, and product model: ZJP6697F7.

Example 4

[0087] A crack-controllable coating was prepared by the following method.

[0088] (1) Gray two-component epoxy primer was sprayed on the surface of a treated metal workpiece. The surface drying time of the gray two-component epoxy primer was 20 minutes, and the hard drying time was 6 hours. The gray two-component epoxy primer was self-dried at 25? C. and the humidity of 55% for 50 minutes to form a first primer layer. The gray two-component epoxy primer was purchased from Bauhinia, and product model: Zipc20P-204.

[0089] (2) According to an average spraying amount of 6.5 m.sup.2/kg with an error within 0.5 m.sup.2/kg, and white nitro crackle lacquer was sprayed on the first primer layer. After tens of seconds, there were large cracks with the average width of 0.6 mm, and width fluctuations were in the range of 0.05 mm. The cracks were black. After 12 hours of hard drying, the first crackle coating layer was formed. The white nitro crackle lacquer was purchased from Bauhinia, and product model: 691-01A.

[0090] (3) Transparent two-component epoxy primer was sprayed on the first crackle coating layer. The surface drying time of the alkyd varnish was 25 minutes, and the hard drying time was 6 hours. The transparent two-component epoxy primer was dried at 25? C. and a humidity of 55% for 50 minutes, so as to form a second primer layer. The transparent two-component epoxy primer was purchased from Bauhinia, and product model: Zipc20P-101.

[0091] (4) According to a spraying amount of 14.5 m.sup.2/kg with the error within 0.5 m.sup.2/kg, transparent nitro crackle varnish was sprayed on the second primer layer. After tens of seconds, there were fine cracks with the cracking width of 0.09 mm, and the width fluctuations were in the range of 0.02 mm. After 4 hours of hard drying, a second crackle coating layer was formed. The transparent nitro crackle varnish was purchased from Bauhinia, and product model: LW-99.

[0092] (5) Cotton cloth dipped high concentration of yellow essence and wiped the surface of the second crackle coating layer. The small cracks were filled with yellow essence, and excess essence was cleaned up. Then, a high yellowing-resistant polyurethane varnish was sprayed and dried, to obtain the crack-controllable coating with the imitation effect of the kiln golden thread. The yellow iron oxide was purchased from Bauhinia, and product model: 694-002. The yellowing-resistant polyurethane varnish was purchased from Bauhinia, and product model: ZJP6697F7.

Examples 5-8

[0093] The differences between the Examples 5-8 and Example 1 were that the self-drying time in step (1) is 26 minutes (Example 5), 1 hour (Example 6), 18 minutes (Example 7), and 1.3 hours (Example 8). The rest steps are the same as Example 1.

Comparative Example 1

[0094] The differences between the comparative example 1 and example 1 were that the white nitro crackle lacquer in step (2) was replaced with a white two-component polyurethane crackle lacquer. The white two-component polyurethane crackle lacquer was prepared according to the formulas and process of the PU crackle lacquer disclosed in the Chinese patent publication No. 102604519A.

Comparative Example 2

[0095] The differences between the comparative example 2 and example 1 were that the transparent nitro crackle varnish in step (4) was replaced with a transparent two-component polyurethane crackle varnish. The transparent two-component polyurethane crackle varnish was prepared in accordance with the PU crackle coating formula (without adding titanium dioxide and other pigments) and process disclosed in the Chinese patent publication No. 102604519A.

Performance Test

[0096] The crack-controllable coatings prepared by the methods described in Examples 1-8 and the comparative examples 1-2 were tested as follows.

[0097] In the preparation process of the crack-controllable coatings, the crack morphology of the first crackle coating layer and the crack morphology of the second crackle coating layer were observed. According to uniformity of distribution of the crack morphology and width reasonableness (in the range of 0.3-0.8 mm was preferred), crack morphology of the first crackle coating layer was classified into Grade I, Grade II, Grade III, and Grade IV. Grade I cracks were uniformly distributed with a width of 0.6-0.8 mm. Grade II cracks were uniformly distributed with a width of 0.5-0.6 mm. Grade III cracks were uniformly distributed with a width of 0.3-0.5 mm. Grade IV represents no crack distribution, and crack width of 0 mm (no cracking). The cracks of the second crackle coating layer were divided into Grade I and Grade IV, due to the fine cracks, and no longer divided into Grade II or Grade III. Grade I cracks were uniformly distributed with a width of 0.08-0.2 mm, and Grade IV represents no crack distribution, and crack width of 0 mm (no cracking).

[0098] The test results were shown in Table 1.

TABLE-US-00001 TABLE 1 Uniformity and width reasonability of cracks in the first and second crackle coating layers Cracks of first crackle Cracks of second crackle coating layer coating layer Width Width Uniformity reasonability Uniformity reasonability Example 1 Grade I Grade I Grade I Grade I Example 2 Grade I Grade II Grade I Grade I Example 3 Grade I Grade II Grade I Grade I Example 4 Grade I Grade II Grade I Grade I Example 5 Grade I Grade I Grade I Grade I Example 6 Grade I Grade II Grade I Grade I Example 7 Grade IV Grade IV Grade I Grade I Example 8 Grade IV Grade IV Grade I Grade I Comparative Grade IV Grade IV Grade I Grade I example 1 Comparative Grade I Grade I Grade IV Grade IV example 2

[0099] Table 1 showed that the preparation method described in this disclosure facilitates the formation of crack-controllable coatings, more particularly to the formation of crackle coating layers which simulate the golden thread-iron wire ceramic crackle effect of the Ge kiln porcelain on various substrates, as shown in FIG. 2.

[0100] It can be demonstrated from the comparison between Comparative example 1 and Example 1 that the performance of Comparative example 1 was inferior to that of Example 1, indicating that replacing the one-component crackle coating with the two-component crackle coating was not conducive to the formation of the crack-controllable coating.

[0101] It can be demonstrated from the comparison between Comparative example 2 and Example 1 that the performance of Comparative example 2 was inferior to that of Example 1, indicating that replacing the one-component crackle coating with the two-component crackle coating was not conducive to the formation of the crack-controllable coating.

[0102] The test results of Examples 5-8 and Example 1 showed that the performance of Examples 7-8 was inferior to that of Examples 5-6, proving that when forming the primer layer, the drying time between 1.5-2.5 times of the surface drying time to 35%-45% of the hard drying time was more conducive to the formation of the crack-controllable coating, preferably, controlling the drying time between 2 times of the surface drying time to 40% of the hard drying time.

[0103] In this disclosure, the preparation method facilitates the formation of the crack-controllable coating, more particularly to crackle coating layers which simulate the golden thread-iron wire ceramic crackle effect of the Ge kiln porcelain on various substrates. In the step (1), the reaction curing of the reaction-curable primer, the limited and ordered semi-cured shrinkage of the coating film in the optimal time between the surface drying and the hard drying, and the limited swelling of the semi-cured coating film by the subsequent crackle primer provides a limited crackle drift for the subsequent crackle primer, provides the basis for the formation of controllable fine cracks, and avoids the uncontrollable cracking of the subsequent crackle primer by using other thermoplastic one-component self-drying primers, see FIGS. 1a and 1b.

[0104] In step (2), the one-component crackle coating and appropriate coating thickness can avoid uncontrolled cracking or inability to crack of two-component reaction crackle coating, and be conducive to the formation of relatively large cracks, in order to form the iron wire effect.

[0105] In steps (3), (4) and (5), the semi-dry cured coating film of the reaction-curable primer is obtained within the optimal time between the surface drying and the hard drying, the one-component crackle coating is thinly coated, and a colorant is used to color the fine cracks, which facilitates the formation of controllable cracks with relatively small plates, so as to form a golden thread effect, as shown in FIG. 2.

[0106] The technical solutions of the present disclosure are described above with reference to the embodiments of the present disclosure. It is clear that described above are merely some embodiments of the disclosure, which are not intended to limit the disclosure. It should be understood that any modifications and replacements made by those skilled in the art without departing from the spirit of the disclosure should fall within the scope of the disclosure defined by the appended claims.