Anti-sagging resin and preparation method thereof and application thereof in preparing high-temperature baking varnish coating

Abstract

The invention discloses an anti-sagging resin and a preparation method thereof and application thereof in preparing a high-temperature baking varnish coating. The preparation method of the anti-sagging resin comprises the following steps: adding a 4-methylbenzylamine solution to a resin, stirring evenly, then dripping a 1,6-hexamethylene diisocyanate solution, stirring, and reacting to obtain an anti-sagging resin containing a compound shown in structure (I). The coating prepared from the anti-sagging resin provided by the invention has a high anti-sagging value, which reaches more than 275 μm under the coating ratio of this experiment; the temperature required for becoming transparent is higher, which is 160° C., and can be applied to high-temperature baking varnish coatings.

Description

Technical Field

[0001] The invention belongs to the field of coatings, and in particular relates to an anti-sagging resin and a preparation method thereof and application thereof in the preparation of high-temperature baking varnish coatings. Background Art

[0002] SCA (Sag Control Agent) means "sag control agent" or "anti-sag agent". This additive is widely used in the field of coatings to prevent the coating from sagging. Its mechanism of action is: during static storage, due to the absence of external force, the anti-sag agent will form a three-dimensional network structure through hydrogen bond interaction to restrain the flow of the coating, so that the coating exhibits a higher initial viscosity; during construction and spraying, due to the action of a certain shear force, the three-dimensional network structure is destroyed, the coating is easier to flow and exhibits a lower viscosity, which is more conducive to construction and leveling; after the external force is removed, the three-dimensional network structure is quickly constructed, and the viscosity returns to a higher value to avoid sagging.

[0003] Traditional anti-sagging agents, including bentonite, fumed silica and polyamide wax, are added in large quantities and require high shear force to disperse evenly during production, which can easily cause dust pollution. More importantly, they cannot be added to varnishes because these products will have an adverse effect on the gloss and transparency of the paint film. Diurea anti-sagging agents can overcome the above shortcomings. During the baking process, the diurea group will react with the amino resin in the curing agent and eventually become transparent, which does not affect the transparency of the paint film.

[0004] The preparation of the diurea compound (II) is described, for example, in US 6420324 B1, and its structural formula is shown below:

[0005]

[0006] The diurea compound is prepared from benzylamine and 1,6-hexamethylene diisocyanate and is widely used in the field of anti-sagging agents for coatings. It has excellent anti-sagging performance and can become transparent under the condition of baking at 140°C. However, its anti-sagging performance will be greatly reduced at high baking temperatures. How to prepare an anti-sagging agent that can still maintain high anti-sagging performance under high-temperature baking has become an urgent problem to be solved. Summary of the invention

[0007] The purpose of the present invention is to overcome the deficiencies of the prior art and provide an anti-sagging resin.

[0008] The second object of the present invention is to provide a method for preparing the anti-sagging resin.

[0009] The third object of the present invention is to provide an application of an anti-sagging resin in the preparation of a high-temperature baking varnish coating.

[0010] The technical solution of the present invention is summarized as follows:

[0011] The preparation method of the anti-sagging resin comprises the following steps:

[0012] Add 4-methylbenzylamine solution to the resin, stir evenly, then drop 1,6-hexamethylene diisocyanate solution into it, stir, and react to obtain an anti-sagging resin containing the compound shown in structure I:

[0013]

[0014] The mass ratio of the 4-methylbenzylamine, the resin and the 1,6-hexamethylene diisocyanate is preferably 2.96-5.92: 80-90: 2.04-4.08.

[0015] The solvent of the 4-methylbenzylamine solution is preferably at least one of aromatic hydrocarbons 100, toluene, p-xylene and butyl acetate; the solvent of the 1,6-hexamethylene diisocyanate solution is preferably at least one of aromatic hydrocarbons 100, toluene, p-xylene and butyl acetate.

[0016] The resin is preferably a polyester resin or an acrylic resin.

[0017] The polyester resin is preferably at least one of SN805, SY961, CFR8675, ETERKYD 50031, ETERKYD50141-TK-40 and ETERKYD 5019-R-40.

[0018] The acrylic resin is preferably at least one of CY951, FX-W9286, HU56020, ETERAC 72827, WAP-347, Setalux1184 and Setalux 1753.

[0019] The reaction conditions are preferably: stirring at 0-25° C. and 300-600 rpm.

[0020] The anti-sagging resin prepared by the above preparation method.

[0021] Application of the anti-sagging resin in the preparation of high-temperature baking varnish coatings.

[0022] Advantages of the present invention:

[0023] The coating prepared with the anti-sagging resin provided by the present invention has a higher anti-sagging value than the coating prepared with the anti-sagging resin (II), reaching more than 275 μm under the varnish ratio in this experiment.

[0024] The coating prepared with the anti-sagging resin provided by the present invention requires a higher temperature of 160° C. to become transparent than the coating prepared with the anti-sagging resin (II), and can be applied to high-temperature baking paint coatings. DETAILED DESCRIPTION

[0025] The present invention is further described below through specific implementation cases. It should be understood by those skilled in the art that the specific implementation examples described herein are only used to explain the present invention and are not used to limit the present invention.

[0026] Unless otherwise specified, the experimental methods used in the implementation scheme are all conventional methods; the materials and reagents used can be obtained from commercial channels unless otherwise specified.

[0027] The varnish base material used in the present invention is prepared by itself, and the ingredient list is as follows.

[0028] Table 1 Varnish base material ingredients

[0029]

[0030] The varnish curing agent used in the present invention is HDI isocyanate solvent-based HDI trimer yellowing-resistant curing agent purchased from Tianjin Aoluqi Chemical Technology Co., Ltd.

[0031] Example 1

[0032] The preparation method of the anti-sagging resin comprises the following steps:

[0033] Add 90.00g of acrylic resin CY951 to a 250mL three-necked flask equipped with a mechanical stirrer, a thermometer, and a dropping funnel, add a solution obtained by mixing 2.96g (24.46mmol) of 4-methylbenzylamine and 2.96g of aromatic hydrocarbon 100, and stir evenly; take another 50mL beaker and add a solution obtained by mixing 2.04g (12.14mmol) of 1,6-hexanediisocyanate and 2.04g of aromatic hydrocarbon 100, stir evenly, and then transfer to a dropping funnel, and add dropwise at 0℃ and a stirring rate of 300rpm. From the start of the dropwise addition, react for 30min to obtain a milky white anti-sagging resin.

[0034] Detection: Take a small amount of the above anti-sagging resin in a centrifuge tube, add ethanol and ultrasonically disperse for 10 minutes. Centrifuge at 10000rpm for 10 minutes, discard the supernatant, add ethanol and continue ultrasonic dispersion, centrifuge twice to wash away the acrylic resin CY951, and obtain a white solid powder. 1 H NMR (DMSO-d6): δ7.06 (s, 8H), 6.14 (s, 2H), 5.82 (s, 2H), 4.09 (s, 4H), 2.94 (s, 4H), 2.21 (s, 6H), 1.30 (s, 8H). Its structural formula is shown in (I):

[0035]

[0036] The application of anti-sagging resin in the preparation of high-temperature baking varnish coating comprises the following steps:

[0037] 2.50 g of the anti-sagging resin was taken into a 50 mL beaker, 7.50 g of the varnish base was added, and the mixture was stirred at 300 rpm for 10 min. 3.33 g of the varnish curing agent was added, and the mixture was stirred for 1 min to obtain a high temperature baking paint.

[0038] Scraping test: Take 5.00g of the above coating on the cardboard, and evenly scrape it with a sag coater. Place the cardboard vertically, and after it is naturally dried, test its anti-sag value to find that it is 275μm.

[0039] Baking experiment: Take another 5.00g of coating on a transparent glass plate, apply it evenly with a sag applicator, place the glass plate on a constant temperature heating table and heat it. The temperature at which it becomes transparent is tested to be 160°C and the time is 30 minutes.

[0040] Example 2

[0041] The preparation method of the anti-sagging resin comprises the following steps:

[0042] Add 85.00g acrylic resin ETERAC 72827, 4.44g (36.69mmol) 4-methylbenzylamine and 2.96g butyl acetate to a 250mL three-necked flask equipped with a mechanical stirrer, a thermometer and a dropping funnel, and stir evenly; take another 50mL beaker and add 3.06g (18.21mmol) 1,6-hexamethylene diisocyanate and 3.06g butyl acetate to a solution, stir evenly and transfer to a dropping funnel, and add dropwise at 10°C and a stirring rate of 400rpm. From the start of the dropwise addition, react for 30 minutes to obtain a milky white anti-sagging resin.

[0043] Detection: A small amount of the anti-sagging resin is taken and solid powder is obtained according to the detection method described in Example 1. After nuclear magnetic resonance detection, its structure is shown in Formula I.

[0044] Experiments have shown that by replacing the acrylic resin ETERAC72827 of this embodiment with acrylic resins FX-W9286, HU56020, WAP-347, Setalux 1184, and a mixture of Setalux 1184 and Setalux 1753 in a mass ratio of 1:1, with the other conditions being the same as this embodiment, anti-sagging resins containing the compound shown in structure (I) are obtained.

[0045] The application of anti-sagging resin in the preparation of high-temperature baking varnish coating comprises the following steps:

[0046] 2.50 g of the anti-sagging resin was taken into a 50 mL beaker, 7.50 g of the varnish base was added, and the mixture was stirred at 300 rpm for 10 min. 3.33 g of the varnish curing agent was added, and the mixture was stirred for 1 min to obtain a high temperature baking paint.

[0047] Scraping test: Take 5.00g of the above coating on the cardboard, and evenly scrape it with a sag coater. Place the cardboard vertically, and after it is naturally dried, test its anti-sag value to find that it is 275μm.

[0048] Baking experiment: Take another 5.00g of coating on a transparent glass plate, apply it evenly with a sag applicator, place the glass plate on a constant temperature heating table and heat it. The temperature at which it becomes transparent is tested to be 160°C and the time is 30 minutes.

[0049] Example 3

[0050] The preparation method of the anti-sagging resin comprises the following steps:

[0051] Add 80.00g of polyester resin SY961, 5.92g (48.92mmol) of 4-methylbenzylamine, 2.96g of toluene, and 2.96g of p-xylene to a 250mL three-necked flask equipped with a mechanical stirrer, a thermometer, and a dropping funnel, and stir evenly; take another 50mL beaker and add 4.08g (24.28mmol) of 1,6-hexanediisocyanate, 2.04g of toluene, and 2.04g of p-xylene to obtain a solution; stir evenly and transfer to a dropping funnel, and drop at 25°C and a stirring rate of 600rpm. From the start of dropwise addition, react for 30 minutes to obtain a milky white anti-sagging resin.

[0052] Detection: A small amount of the anti-sagging resin is taken and solid powder is obtained according to the detection method described in Example 1. After nuclear magnetic resonance detection, its structure is shown in Formula I.

[0053] Experiments have shown that by replacing the polyester resin SY961 in this embodiment with polyester resin SN805, CFR8675, ETERKYD 50031, ETERKYD 50141-TK-40, ETERKYD 5019-R-40 or a mixture of SY961 and CFR8675 in a mass ratio of 1:1, and the other conditions being the same as in this embodiment, anti-sagging resins containing the compound shown in structure (I) are obtained.

[0054] The application of anti-sagging resin in the preparation of high-temperature baking varnish coating comprises the following steps:

[0055] 2.50 g of the anti-sagging resin was taken into a 50 mL beaker, 7.50 g of the varnish base was added, and the mixture was stirred at 300 rpm for 10 min. 3.33 g of the varnish curing agent was added, and the mixture was stirred for 1 min to obtain a high temperature baking paint.

[0056] Scraping test: Take 5.00g of the above coating on the cardboard, and evenly scrape it with a sag coater. Place the cardboard vertically, and after it is naturally dried, test its anti-sag value to find that it is 275μm.

[0057] Baking experiment: Take another 5.00g of coating on a transparent glass plate, apply it evenly with a sag applicator, place the glass plate on a constant temperature heating table and heat it. The temperature at which it becomes transparent is tested to be 160°C and the time is 30 minutes.

[0058] Comparative Example 1

[0059] Add 90.00 g of acrylic resin CY951, 2.80 g (26.17 mmol) of benzylamine and 2.80 g of aromatic hydrocarbon 100 to a 250 mL three-necked flask equipped with a mechanical stirrer, a thermometer and a dropping funnel, and stir evenly. Take another 50 mL beaker and add 2.20 g (13.10 mmol) of 1,6-hexanediisocyanate and 2.20 g of aromatic hydrocarbon 100 to obtain a mixed solution, stir evenly and transfer to a dropping funnel, and add dropwise at 25 ° C and a stirring rate of 300 rpm. From the start of the dropwise addition, the reaction lasts for 30 minutes to obtain a milky white anti-sagging resin.

[0060] Detection: Take a small amount of the above anti-sagging resin in a centrifuge tube, add ethanol and ultrasonically disperse for 10 minutes. Centrifuge at 10000rpm for 10 minutes, discard the supernatant, add ethanol and continue ultrasonic dispersion, centrifuge twice to wash away the acrylic resin CY951, and obtain a white solid powder. 1 H NMR (DMSO-d6) δ7.21 (d, J = 55.7 Hz, 10H), 6.21 (s, 2H), 5.86 (s, 2H), 4.15 (s, 4H), 2.95 (s, 4H), 1.32 (s, 4H), 1.20 (s, 4H), and its structural formula is shown in (II):

[0061]

[0062] The application of anti-sagging resin II in the preparation of coatings comprises the following steps:

[0063] 2.50 g of the anti-sagging resin was taken into a 50 mL beaker, 7.50 g of the varnish base was added, and the mixture was stirred at 300 rpm for 10 min. 3.33 g of the varnish curing agent was then added, and the mixture was stirred for 1 min to obtain a coating.

[0064] Scraping test: Take 5.00g of the above coating on the cardboard, and evenly scrape it with a sag coater. Place the cardboard vertically, and after it is naturally dried, test its anti-sag value to be 225um.

[0065] Baking experiment: Take another 5.00g of coating on a transparent glass plate, apply it evenly with a sag applicator, place the glass plate on a constant temperature heating table and heat it. The temperature at which it becomes transparent is tested to be 140°C and the time is 30 minutes.

[0066] Based on the above examples and comparative examples, diurea anti-sagging resins with different structures were prepared, and the results of the scraping test and baking test were as follows:

[0067] Table 2 Summary of scraping test results

[0068]

[0069] The maximum film thickness of the thickness gauge used in the present invention is 275 μm. The anti-sagging values ​​of the anti-sagging resin coatings prepared in Examples 1-3 are all higher than 275 μm. Since thicknesses above 275 μm are not within the measurement range, the maximum film thickness obtained by measurement is used for recording.

[0070] Table 3 Summary of baking test results

[0071]

[0072] By comparing the performances of different embodiments and comparative examples, it is found that the coating prepared with the anti-sagging resin prepared in the present invention not only has excellent anti-sagging performance, but also becomes transparent at a higher baking temperature, and can be used as a high-temperature baking paint.

Claims

1. A method for preparing an anti-sagging resin, characterized in that The steps include: Add 4-methylbenzylamine solution to the resin, stir evenly, then drop 1,6-hexamethylene diisocyanate solution, stir, and react to obtain an anti-sagging resin containing the compound shown in structure (I): The solvent of the 4-methylbenzylamine solution is at least one of aromatic hydrocarbon 100, toluene, p-xylene and butyl acetate; the solvent of the 1,6-hexamethylene diisocyanate solution is at least one of aromatic hydrocarbon 100, toluene, p-xylene and butyl acetate; The resin is polyester resin or acrylic resin; The polyester resin is at least one of SN805, SY961, CFR8675, ETERKYD 50031, ETERKYD 50141-TK-40 and ETERKYD 5019-R-40; The acrylic resin is at least one of CY951, FX-W9286, HU56020, ETERAC 72827, WAP-347, Setalux1184 and Setalux 1753.

2. The preparation method according to claim 1, characterized in that The mass ratio of the 4-methylbenzylamine, the resin and the 1,6-hexamethylene diisocyanate is 2.96-5.92: 80-90: 2.04-4.

08.

3. The preparation method according to claim 1, characterized in that The reaction conditions are: stirring at 0-25°C and 300-600 rpm.

4. The anti-sagging resin prepared by the preparation method according to any one of claims 1 to 3.

5. Use of the anti-sagging resin of claim 4 in the preparation of high-temperature baking varnish coatings.

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