Solvent type coil coating as well as preparation method and application thereof

Abstract

The invention relates to a solvent type coiled material coating which comprises the following components in parts by weight: 30-40 parts of saturated polyester resin, 10-20 parts of modified polyester resin, 6-10 parts of amino resin, 0.2-1.0 part of a catalyst, 0.5-1.5 parts of a light stabilizer, 14-22 parts of pigment, 4.8-12 parts of an auxiliary agent and 8-25 parts of a solvent. According to the solvent type coiled material coating, the modified polyester resin is introduced to replace main resin in an existing technical scheme, under the synergistic effect of the saturated polyester resin and the modified polyester resin, the amino resin, the catalyst, the light stabilizer and the like are matched, the 400-hour chromatic aberration of QUVB in an artificial accelerated aging test can be effectively reduced, meanwhile, the curing and performance of a coating film are not affected, and the coating film has a good application prospect. And the paint can be widely applied to various coil steel base materials. The invention further discloses a preparation method and application of the solvent type coil coating.

Description

Technical Field

[0001] The present invention relates to the field of solvent-based coil coatings, and in particular to a solvent-based coil coating and a preparation method and application thereof. Background Art

[0002] Pre-coated metal coils are primarily used as building materials. They can be combined with lightweight steel frames and are suitable for the construction of exterior wall panels, curtain walls, roof panels, interior partitions, rolling doors, garage doors, and awnings for industrial plants, public facilities, private residences, stations, and commercial kiosks. Pre-coated metal coils account for over half of total pre-coated metal coil production. With increasingly fierce competition in the domestic coil market, the industry's performance requirements for pre-coated metal coils are becoming increasingly stringent. The corresponding coil coatings must provide excellent protection and outdoor durability while also meeting certain bending requirements. Furthermore, as people's living standards continue to improve, personalized needs and environmental protection requirements are becoming increasingly stringent. Environmental protection and cost-effectiveness are also trends in the development of coil coatings.

[0003] Because outdoor weatherability requires a long exposure period to be effective, while accelerated UVB testing (QUVB) has a shorter testing period and correlates well with outdoor exposure data, QUVB testing is often used in place of outdoor weathering testing. For common polyester coatings, the QUVB 400-hour color difference requirement is less than 6.0. To achieve this, existing techniques typically add UV absorbers or UV stabilizers (or a combination of both) to the formulation. While this can reduce the QUVB 400-hour color difference to a certain extent, it can affect film curing and performance, and does not completely resolve the problem.

[0004] In view of this, there is an urgent need in the art to develop a solvent-based coil coating that can effectively reduce the QUVB 400-hour color difference without affecting the coating film curing and performance, thereby solving the problems faced in the existing technical field. Summary of the Invention

[0005] Based on the above facts, the present invention aims to provide a solvent-based coil coating that introduces a modified polyester resin to replace the main resin of the existing technical solution. Under the synergistic effect of the saturated polyester resin and the modified polyester resin, combined with an amino resin, a catalyst, a light stabilizer, etc., it can effectively reduce the QUVB 400-hour color difference without affecting the coating film curing and performance.

[0006] A first aspect of the present invention provides a solvent-based coil coating comprising, by weight:

[0007]

[0008]

[0009] saturated polyester resin

[0010] In some embodiments of the present invention, the saturated polyester resin has a solid content of 60-70%, a number average molecular weight of 3000-6000, and a hydroxyl value of 40-60 mgKOH / g.

[0011] Specifically, the saturated polyester resin is preferably a polyester resin with a model number of DYNAPOL LH538-02 provided by Evonik Industries AG.

[0012] Modified polyester resin

[0013] In some embodiments of the present invention, the solid content of the modified polyester resin is 60-70%. It not only has good compatibility with the saturated polyester resin, but can also be cross-linked and cured with the amino resin, etc., to improve the gloss retention of the coating and reduce color difference.

[0014] Specifically, the modified polyester resin is preferably one or more of the polyester resins ETERKYD 5055-R-65-3, ETERKYD 5064-R-70-3, and ETERKYD 5055-R-70 provided by Changxing Chemical Industry Co., Ltd.

[0015] amino resin

[0016] In the present invention, the amino resin is a methyl etherified amino resin, which can produce curing and cross-linking reactions with the polyester resin.

[0017] Specifically, the amino resin is preferably one or more of the amino resins CYMEL 303 provided by Allnex Resins, LUWIPAL 066 provided by BASF, and YP5603 provided by Shanghai Yuanbang.

[0018] catalyst

[0019] In the present invention, the catalyst is an organic sulfonic acid catalyst, which can catalyze the curing and cross-linking reaction of the polyester resin and the amino resin, reduce the reaction temperature, and shorten the curing reaction time.

[0020] Specifically, the catalyst is preferably one of the catalysts NACURE 1051 and NACURE 1419 provided by King's Company of the United States, or a combination thereof.

[0021] Light stabilizers

[0022] In the present invention, the light stabilizer is selected from one or more of ultraviolet light absorbers and ultraviolet light stabilizers.

[0023] In some preferred embodiments of the present invention, the light stabilizer is a liquid hindered amine light stabilizer, which has low alkalinity and can avoid reaction with acidic components in the coating to a certain extent, effectively preventing paint diseases such as cracking, gloss loss, and powdering, thereby increasing the service life of the coating.

[0024] Specifically, the light stabilizer is preferably provided by BASF. 123. 400 of one or a combination of light stabilizers.

[0025] pigment

[0026] In the present invention, the pigment includes organic pigments and inorganic pigments. The choice of pigment depends on the application scenario, including but not limited to white pigment, blue pigment, etc.

[0027] In some preferred embodiments of the present invention, the white pigment is selected from titanium dioxide model NTR 606 provided by Ningbo Xinfu Titanium Dioxide Co., Ltd., which adopts inorganic dense coating treatment and can provide excellent weather resistance and hiding power; the blue pigment used is selected from one of the phthalocyanine blue BNCF model PB 15:2 provided by Jiangsu Shuangle Chemical and the phthalocyanine blue SINCO BLUE 4372-002 provided by Nanjing Xincai Technology Co., Ltd., or a combination thereof, which can provide a bright reddish blue color and outdoor weather resistance.

[0028] additives

[0029] In the present invention, the additives include dispersants, matting powders, defoamers, leveling agents, anti-settling agents, wax slurries and wax powders. In parts by weight, the solvent-based coil coating includes:

[0030]

[0031]

[0032] Wherein, the dispersant is a polyurethane type dispersant, which can disperse and stabilize the pigment; and the matting powder is precipitated silica.

[0033] Specifically, the dispersant is selected from one or a combination of dispersants with model numbers BYK-161 and BYK 163 provided by BYK; the matting powder is selected from one or a combination of matting powders with model numbers TYS-180 provided by Shanxi Tianyi Nanotechnology Co., Ltd. and TSA-560 provided by Lengshuijiang San A New Materials Co., Ltd.

[0034] solvent

[0035] In the present invention, the solvent is selected from one or more of propylene glycol methyl ether acetate (PMA), dibasic acid esters, mixed dibasic acid dimethyl ester (MDBE), S-#100 aromatic solvent oil (hereinafter referred to as #100), ethylene glycol butyl ether (BCs), and n-butanol.

[0036] The second aspect of the present invention provides a method for preparing the solvent-based coil coating according to the first aspect of the present invention, comprising the following steps:

[0037] S1: Add saturated polyester resin, solvent and dispersant into the container in sequence, and stir at a speed of 200-400 rpm for 10-15 minutes;

[0038] S2: adding pigment and anti-settling agent in sequence while stirring, and continuing stirring at a speed of 300-500 rpm for 15-30 minutes to obtain mixture A;

[0039] S3: Grind the mixture A with a grinder to a fineness of no more than 15 μm to obtain a mixture B;

[0040] S4: stirring mixture B at a speed of 300-500 rpm, adding modified polyester resin, amino resin, wax slurry, wax powder, leveling agent, defoaming agent, matting powder, catalyst and light stabilizer under stirring, and continuing stirring for 15-30 minutes to obtain mixture C;

[0041] S5: The viscosity of the mixture C is adjusted to 100-140 seconds / T-4 cup / measured at 25° C. The mixture is filtered and packaged to obtain the solvent-based coil coating.

[0042] The third aspect of the present invention provides an application of the solvent-based coil coating according to the first aspect of the present invention, comprising the following steps:

[0043] A chrome-free primer is applied to a pre-treated galvanized steel sheet using a wire rod roller, and after drying and curing, a primer coating with a thickness of 4-6 μm is obtained. Then, the solvent-based coil coating is applied to the primer coating using a wire rod roller, and baked in an oven to obtain a topcoat coating with a film thickness of 14-16 μm.

[0044] Specifically, the thickness of the galvanized steel sheet is 0.40-0.60 mm; the temperature of the oven is 300-350° C., and the baking time is 20-40 seconds. In a specific example, the temperature of the oven is 320° C., and the baking time is 30 seconds.

[0045] The pre-treatment specifically refers to a series of operations of degreasing, washing, chromium-free passivation and drying the galvanized steel sheet.

[0046] When the chrome-free primer is roller-coated, the wire rod model used is RDS10#, and when the solvent-based coil coating is roller-coated, the wire rod model used is RDS20#.

[0047] The beneficial effects of the present invention are as follows:

[0048] The present invention provides a solvent-based coil coating, which introduces a modified polyester resin to replace the main resin of the existing technical solution. Under the synergistic effect of the saturated polyester resin and the modified polyester resin, combined with an amino resin, a catalyst, a light stabilizer, etc., it can effectively reduce the QUVB 400-hour color difference without affecting the coating film curing and performance, thereby improving the gloss retention rate of the coating and being widely applicable to various types of coil steel substrates. DETAILED DESCRIPTION

[0049] In order to illustrate the present invention more clearly, the present invention will be further described below in conjunction with specific examples and comparative examples. It should be understood by those skilled in the art that the content specifically described below is illustrative and non-restrictive and should not be used to limit the scope of protection of the present invention. The experimental methods used in the following examples and comparative examples are conventional methods unless otherwise specified, and the raw materials and reagents used are products that can be purchased from conventional commercial channels unless otherwise specified.

[0050] The above technical solution is described below in conjunction with specific embodiments.

[0051] Examples 1-5: Solvent-based coil coatings 1-5

[0052] The solvent-based coil coatings 1-5 of the present invention were prepared according to the formula in Table 1 below. The preparation steps are as follows:

[0053] S1: Add saturated polyester resin, solvent and dispersant into the container in sequence, and stir at a speed of 200-400 rpm for 10-15 minutes;

[0054] S2: Add pigment and anti-settling agent in sequence while stirring, and continue stirring at a speed of 300-500 rpm for 15-30 minutes to obtain mixture A;

[0055] S3: Grind the mixture A with a grinder to a fineness of no more than 15 μm to obtain a mixture B;

[0056] S4: stirring mixture B at a speed of 300-500 rpm, adding modified polyester resin, amino resin, wax slurry, wax powder, leveling agent, defoaming agent, matting powder, catalyst and light stabilizer under stirring, and continuing stirring for 15-30 minutes to obtain mixture C;

[0057] S5: Adjust the viscosity of the mixture C to 100-140 seconds / T-4 cup / measured at 25° C. Filter and package to obtain the solvent-based coil coating 1-5.

[0058] Comparative Example 1: Coating 1 as a comparative example

[0059] Coating 1 as a comparative example was prepared according to the formula in Table 1 below. The preparation steps are as follows:

[0060] S1: Add saturated polyester resin, solvent and dispersant into the container in sequence, and stir at a speed of 200-400 rpm for 10-15 minutes;

[0061] S2: adding pigment and anti-settling agent in sequence while stirring, and continuing stirring at a speed of 300-500 rpm for 15-30 minutes to obtain mixture A;

[0062] S3: Grind the mixture A with a grinder to a fineness of no more than 15 μm to obtain a mixture B;

[0063] S4: stirring mixture B at a speed of 300-500 rpm, adding amino resin, wax slurry, wax powder, leveling agent, defoaming agent, matting powder, catalyst and light stabilizer under stirring, and continuing stirring for 15-30 minutes to obtain mixture C;

[0064] S5: The viscosity of the mixture C was adjusted to 100-140 seconds / T-4 cup / measured at 25°C, and the mixture was filtered and packaged to obtain the coating 1 as a comparative example.

[0065] It should be noted that the comparative example 1 does not contain a modified polyester resin and is not within the scope of protection of the present invention, so it is referred to as comparative example 1. The absence of a modified polyester resin results in a lower gloss retention rate after 400 hours of QUVB testing and a larger color difference, resulting in failure.

[0066] Comparative Example 2: Coating 2 as a comparative example

[0067] Coating 2 as a comparative example was prepared according to the formulation in Table 1 below, and the preparation steps were the same as those of Examples 1-5.

[0068] It should be noted that the comparative example 2 contains an excessive amount of modified polyester resin and too little saturated polyester resin and amino resin, which is not within the scope of the present invention and is therefore designated as comparative example 2. This adjustment will result in a decrease in the pencil hardness of the coating and a lower coating rate.

[0069] Comparative Example 3: Coating 3 as a comparative example

[0070] Coating 3 as a comparative example was prepared according to the formula in Table 1 below. The preparation steps are as follows:

[0071] S1: Add saturated polyester resin, solvent and dispersant into the container in sequence, and stir at a speed of 200-400 rpm for 10-15 minutes;

[0072] S2: Add pigment and anti-settling agent in sequence while stirring, and continue stirring at a speed of 300-500 rpm for 15-30 minutes to obtain mixture A;

[0073] S3: Grind the mixture A with a grinder to a fineness of no more than 15 μm to obtain a mixture B;

[0074] S4: stirring mixture B at a speed of 300-500 rpm, adding modified polyester resin, amino resin, wax slurry, wax powder, leveling agent, defoaming agent, matting powder, and catalyst under stirring, and continuing stirring for 15-30 minutes to obtain mixture C;

[0075] S5: The viscosity of the mixture C was adjusted to 100-140 seconds / T-4 cup / measured at 25°C, and the mixture was filtered and packaged to obtain coating 3 as a comparative example.

[0076] It should be noted that the comparative example 3 does not contain a light stabilizer and is not within the scope of protection of the present invention, so it is referred to as comparative example 3. The absence of a light stabilizer will result in a lower gloss retention rate after 400 hours of QUVB testing and a larger color difference, resulting in failure.

[0077] Comparative Example 4: Coating 4 as a comparative example

[0078] Coating 4 as a comparative example was prepared according to the formulation in Table 1 below, and the preparation steps were the same as those of Examples 1-5.

[0079] It should be noted that the coating 4 as a comparative example contains an excessive amount of modified polyester resin and an excessive amount of saturated polyester resin, which is not within the scope of protection of the present invention and is therefore referred to as comparative example 4. This adjustment will result in a reduced coating rate.

[0080] Comparative Example 5: Coating 5 as a comparative example

[0081] Coating 5 as a comparative example was prepared according to the formulation in Table 1 below, and the preparation steps were the same as those of Examples 1-5.

[0082] It should be noted that Coating 5, as a comparative example, contains an excessive amount of saturated polyester resin and an insufficient amount of modified polyester resin, which is outside the scope of protection of the present invention and is therefore designated as Comparative Example 5. This adjustment may result in the risk of failing the QUVB 400-hour gloss retention and color difference test.

[0083] Table 1 Raw material components of Examples 1-5 and Comparative Examples 1-5

[0084]

[0085]

[0086] On 0.50 mm thick galvanized steel sheets that had undergone a series of pretreatments, including degreasing, washing, chromium-free passivation, and drying, a chromium-free primer was first roller-coated using an RDS10# wire rod and dried to cure, forming a primer coating with a thickness of 4-6 μm. The coatings obtained in Examples 1-5 and Comparative Examples 1-5 were then roller-coated onto the primer coating using an RDS20# wire rod. The sheets were then placed in a 320°C electric oven and cured for approximately 30 seconds to form a topcoat coating with a thickness of 14-16 μm. Performance testing of the topcoat coatings is shown in Table 2 below.

[0087] Table 2 Performance test results of the topcoat coatings obtained in Examples 1-5 and Comparative Examples 1-5

[0088]

[0089] As can be seen from the results in Table 2, the solvent-based coil coatings 1-5 obtained in Examples 1-5 can effectively improve the QUVB 400-hour gloss retention rate by more than 40% while meeting the conventional physical property requirements of the coating film, and the color difference is less than 6.0. However, the coating component of Comparative Example 1 does not contain a modified polyester resin, and the QUVB 400-hour gloss retention rate and color difference are both unqualified. The coating component of Comparative Example 2 contains an excessive amount of modified polyester resin, and the amount of saturated polyester resin and amino resin is too small, resulting in an unqualified pencil hardness of the coating. The coating component of Comparative Example 3 does not contain a light stabilizer, and the QUVB 400-hour color difference is unqualified. The coating component of Comparative Example 4 contains an excessive amount of modified polyester resin, and the coating rate is unqualified. The coating component of Comparative Example 5 contains too little modified polyester resin, and the QUVB 400-hour gloss retention rate and color difference are both unqualified.

[0090] In summary, the solvent-based coil coating of the present invention can effectively reduce the QUVB 400-hour color difference without affecting the coating film curing and performance, improve the gloss retention rate of the coating, and can be widely applied to various types of coil steel substrates.

[0091] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not limitations on the implementation methods of the present invention. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is impossible to list all the implementation methods here. All obvious changes or modifications derived from the technical solution of the present invention are still within the scope of protection of the present invention.

Claims

1. A solvent-based coil coating comprising, by weight:

2. The solvent-based coil coating according to claim 1, characterized in that The saturated polyester resin has a solid content of 60-70%, a number average molecular weight of 3000-6000, and a hydroxyl value of 40-60 mgKOH / g. Preferably, the saturated polyester resin is a polyester resin with a model number of DYNAPOL LH 538-02 provided by Evonik Industries.

3. The solvent-based coil coating according to claim 1, characterized in that: The solid content of the modified polyester resin is 60-70%. Preferably, the modified polyester resin is selected from one or more of the polyester resins ETERKYD5055-R-65-3, ETERKYD 5064-R-70-3, and ETERKYD 5055-R-70 provided by Changxing Chemical Industry Co., Ltd.

4. The solvent-based coil coating according to claim 1, characterized in that The amino resin is a methyl etherified amino resin; preferably, the amino resin is selected from one or more of the amino resins of model CYMEL 303 provided by Allnex Resins, model LUWIPAL 066 provided by BASF, and model YP5603 provided by Shanghai Yuanbang.

5. The solvent-based coil coating according to claim 1, characterized in that The catalyst is an organic sulfonic acid catalyst; preferably, the catalyst is selected from one or a combination of catalysts NACURE 1051 and NACURE 1419 provided by King's Company, USA.

6. The solvent-based coil coating according to claim 1, characterized in that: The light stabilizer is selected from one or more of ultraviolet light absorbers and ultraviolet light stabilizers; preferably, the light stabilizer is a liquid hindered amine light stabilizer; more preferably, the light stabilizer is selected from the type provided by BASF 123. 400 of one or a combination of light stabilizers.

7. The solvent-based coil coating according to claim 1, characterized in that: The pigment includes organic pigments and inorganic pigments; preferably, the pigment is selected from one or more of titanium dioxide model NTR 606 provided by Ningbo Xinfu Titanium Dioxide Co., Ltd., phthalocyanine blue BNCF model PB 15:2 provided by Jiangsu Shuangle Chemical, and phthalocyanine blue SINCO BLUE4372-002 provided by Nanjing Xincai Technology Co., Ltd., and the solvent is selected from one or more of propylene glycol methyl ether acetate (PMA), divalent acid esters, mixed dibasic acid dimethyl ester (MDBE), S-#100 aromatic solvent oil, ethylene glycol butyl ether (BCs), and n-butanol.

8. The solvent-based coil coating according to claim 1, characterized in that The additives include dispersants, matting powder, defoaming agents, leveling agents, anti-settling agents, wax slurry, wax powder, and the solvent-based coil coating includes, by weight: The dispersant is a polyurethane type dispersant, and the matting powder is precipitated silica; preferably, the dispersant is selected from one or a combination of dispersants with models BYK-161 and BYK 163 provided by BYK, and the matting powder is selected from one or a combination of matting powders with model TYS-180 provided by Shanxi Tianyi Nano Technology Co., Ltd. and model TSA-560 provided by Lengshuijiang San A New Materials Co., Ltd.

9. A method for preparing a solvent-based coil coating according to claim 8, characterized in that: The steps include: S1: Add saturated polyester resin, solvent and dispersant into the container in sequence, and stir at a speed of 200-400 rpm for 10-15 minutes; S2: Add pigment and anti-settling agent in sequence while stirring, and continue stirring at a speed of 300-500 rpm for 15-30 minutes to obtain mixture A; S3: Grind the mixture A with a grinder to a fineness of no more than 15 μm to obtain a mixture B; S4: stirring mixture B at a speed of 300-500 rpm, adding modified polyester resin, amino resin, wax slurry, wax powder, leveling agent, defoaming agent, matting powder, catalyst and light stabilizer under stirring, and continuing stirring for 15-30 minutes to obtain mixture C; S5: The viscosity of the mixture C is adjusted to 100-140 seconds / T-4 cup / measured at 25° C. The mixture is filtered and packaged to obtain the solvent-based coil coating.

10. A use of the solvent-based coil coating according to any one of claims 1 to 8, characterized in that: The steps include: A chrome-free primer is applied to a pre-treated galvanized steel sheet using a wire rod roller, and after drying and curing, a primer coating with a thickness of 4-6 μm is obtained. Then, the solvent-based coil coating is applied to the primer coating using a wire rod roller, and baked in an oven to obtain a topcoat coating with a film thickness of 14-16 μm. Preferably, the thickness of the galvanized steel sheet is 0.40-0.60 mm. More preferably, the baking temperature of the solvent-based coil coating is set to 300-350° C., and the baking time is set to 20-40 s.

Images