High heat-resistant carboxyl type acrylic resin for powder coating and synthesis method thereof

Abstract

The application discloses a kind of high heat-resistant carboxyl type acrylic resin for powder coating and synthesis method thereof, belong to acrylic resin powder coating technical field, including the following weight percentage of raw materials: vinyl poly silesquioxane 5-10%, (methyl) acrylic acid monomer 20-25%, (methyl) acrylic alkyl ester monomer 50-55%, dimethylaminoethyl methacrylate 5-10%, styrene base monomer 10-20%, first initiator 2-5%, second initiator 0.2-0.5%, curing accelerator 0.1-1%, the sum of weight percentage of each raw material is equal to 100%. The application is modified by copolymerization of vinyl poly silesquioxane to acrylic resin, amino group is introduced at the same time and crosslinked with curing accelerator, which improves the high heat-resistant performance and mechanical properties of acrylic resin, and can provide excellent high heat-resistant performance and impact resistance for coating.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of acrylic resin powder coatings, and particularly relates to a high-heat-resistant carboxyl type acrylic resin for powder coatings and a synthesis method thereof. BACKGROUND

[0002] As a commonly used extinction resin crosslinking agent in powder coatings, the carboxyl type acrylic resin is widely used in the fields of automobiles, household appliances and high-grade decoration, and has a broad application prospect. When the acrylic resin is applied to coatings for ovens, boilers, heat exchangers, automobile parts, cooking components and cookware, etc., it is required to show high-temperature resistance, but the coating has poor impact resistance after being subjected to high temperature above 350 DEG C.

[0003] In order to solve the above technical problems, the application provides a high-heat-resistant carboxyl type acrylic resin for powder coatings and a synthesis method thereof. SUMMARY

[0004] The application aims to provide a high-heat-resistant carboxyl type acrylic resin for powder coatings and a synthesis method thereof, so as to solve the following technical problem: when the acrylic resin is applied to powder coatings, the coating has poor impact resistance after being subjected to high temperature above 350 DEG C.

[0005] The object of the application can be achieved by the following technical solutions.

[0006] A high-heat-resistant carboxyl type acrylic resin for powder coatings comprises the following raw materials in percentage by weight:

[0007] vinyl polysilsesquioxane 5-10%, (meth)acrylic acid monomer 20-25%, (meth)acrylic alkyl ester monomer 50-55%, dimethylaminoethyl methacrylate 5-10%, styrene-based monomer 10-20%, first initiator 2-5%, second initiator 0.2-0.5%, and curing accelerator 0.1-1%, and the sum of the percentages by weight of the raw materials is equal to 100%.

[0008] As a further scheme of the application, the vinyl polysilsesquioxane is any one of monovinyl cage-type polysilsesquioxane and polyvinyl cage-type polysilsesquioxane; preferably, the vinyl polysilsesquioxane is monovinyl cage-type polysilsesquioxane.

[0009] As a further scheme of the application, the (meth)acrylic acid monomer is any one of methacrylic acid and acrylic acid.

[0010] As a further aspect of the present application, the (meth)acrylic alkyl ester monomer is any one or more of methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, isobutyl acrylate, tert-butyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, octadecyl acrylate, cyclohexyl acrylate, isobornyl acrylate, benzyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, tert-butyl methacrylate, isobutyl methacrylate, 2-ethylhexyl methacrylate, dodecyl methacrylate, octadecyl methacrylate, cyclohexyl methacrylate, dimethylaminoethyl methacrylate, isobornyl methacrylate, in any proportion.

[0011] As a further aspect of the present application, the styrene-based monomer is any one of methylstyrene, dimethylstyrene, trimethylstyrene, ethylstyrene, diethylstyrene, triethylstyrene, propylstyrene, butylstyrene, hexylstyrene, heptylstyrene, octylstyrene; preferably, the styrene-based monomer is styrene.

[0012] As a further aspect of the present application, the first initiator and the second initiator are any one of 2,2'-azobisisobutyronitrile, benzoyl peroxide; preferably, the first initiator and the second initiator are both benzoyl peroxide.

[0013] As a further aspect of the present application, the curing accelerator is any one of an imidazole-based curing accelerator, a quaternary phosphonium salt-based curing accelerator; preferably, the curing accelerator is a quaternary phosphonium salt-based curing accelerator.

[0014] As a further aspect of the present application, the synthesis method of the high-heat-resistant carboxyl-type acrylic resin for powder coatings specifically comprises the following steps:

[0015] Step one, a free radical polymerization solvent is added to a reaction vessel, stirred and heated to a reflux state, and vinyl polysilsesquioxane, (meth)acrylic monomer, (meth)acrylic alkyl ester monomer, dimethylaminoethyl methacrylate, styrene-based monomer and first initiator are uniformly mixed, and the mixture is added dropwise into the refluxing solvent within 3-3.5 h, after the dropwise addition is completed, the reaction is carried out under reflux for 2 h, a mixed solution of the second initiator and the free radical polymerization solvent is added dropwise, the dropwise addition is completed within 10 min, and then the reaction is carried out under reflux for 2 h;

[0016] Step two, after the reflux reaction is completed, a curing accelerator is added, the solvent is removed by distillation, when the temperature of the reaction system reaches 180°C, the reaction is carried out under a vacuum degree of -0.09 MPa for 0.5 h, after the reaction is completed, the vacuum is released, the material is discharged and cooled, and a high-heat-resistant carboxyl-type acrylic resin for powder coatings is obtained.

[0017] As a further scheme of the present application, the radical polymerization solvent is any one or more of toluene, xylene, butyl acetate, ethyl acetate mixed in any ratio; preferably, the radical polymerization solvent is xylene; the total mass of the radical polymerization solvent in step one is 90-100% of the total weight of the raw materials, and the mass ratio of the second initiator to the radical polymerization solvent in the mixed solution of the second initiator and the radical polymerization solvent is 1:20.

[0018] As a further scheme of the present application, the Tg (glass transition temperature) of the high-heat-resistant carboxyl-type acrylic resin for powder coating is 50-80℃, the weight average molecular weight is 10000-20000, and the molecular weight distribution is 1.8-2.2.

[0019] The present application has the following advantages:

[0020] The high-heat-resistant carboxyl-type acrylic resin of the present application is obtained by radical polymerization reaction of a vinyl poly-silsesquioxane, a (meth)acrylic monomer, a (meth)acrylic alkyl ester monomer, dimethylaminoethyl methacrylate, and a styrene-based monomer under the action of a first initiator and a second initiator. The carboxyl group is directly introduced through the (meth)acrylic monomer, and an acrylic resin with an acid value of 140 or more is prepared, which has high reactivity and crosslinking density. The vinyl poly-silsesquioxane is an organic / inorganic hybrid material with high thermal stability and excellent mechanical properties. The vinyl poly-silsesquioxane copolymerizes with the acrylic resin, introduces amino groups and crosslinks with a curing accelerator, and improves the high-heat-resistant performance and mechanical properties of the acrylic resin, which can provide the coating with excellent high-heat-resistant performance and impact resistance. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0022] Embodiment 1

[0023] A synthesis method of a high-heat-resistant carboxyl-type acrylic resin for powder coating, specifically comprising the following steps:

[0024] Step one, 900g of xylene was added into a 3000ml three-necked flask, and then the flask was heated to reflux state under stirring. 50g of monovinylcage polysilsesquioxane, 250g of acrylic acid, 150g of methyl methacrylate, 350g of butyl acrylate, 100g of dimethylaminoethyl methacrylate, 100g of styrene and 35g of 2,2'-azobisisobutyronitrile (first initiator) were mixed uniformly, and then the mixture was added dropwise into the refluxing solvent within 3-3.5h. After the dropwise addition was completed, the reaction was carried out under reflux for 2h. Then, 5g of 2,2'-azobisisobutyronitrile (second initiator) and 100g of xylene were mixed to form a solution, and the solution was added dropwise into the reaction system within 10min. Then, the reaction was carried out under reflux for 2h.

[0025] Step two, after the reflux reaction was completed, 2g of SA242 (SA242 is a quaternary phosphonium salt curing accelerator, which was produced by Lianganjietongda New Material Co., Ltd.) was added into the reaction system, and then the solvent xylene was removed by distillation. When the temperature of the reaction system reached 180℃, the reaction was carried out under the condition of vacuum degree of -0.09MPa for 0.5h. After the reaction was completed, the vacuum was released, and the reaction system was cooled to obtain a high heat-resistant carboxyl type acrylic resin for powder coating (the acid value was 188mgKOH / g, the weight average molecular weight was 18900, the molecular weight distribution was 2.1, and the Tg was 66℃).

[0026] Examples 2-4 and Comparative Example 1

[0027] The synthesis method of the examples and the comparative example was the same as that of Example 1. The specific formula components and performance data are shown in Table 1.

[0028] Table 1

[0029]

[0030]

[0031] Application Examples 1-4 and Comparative Application Example 1

[0032] The high heat-resistant carboxyl type acrylic resin for powder coating obtained in Examples 1-4 and Comparative Example 1 was physically blended according to the powder coating components shown in Table 2, and then melt-mixed, sheeted, cooled and broken into fine powder using a twin-screw extruder. Finally, the powder was sieved through a 200 mesh screen, and then sprayed onto the surface of an aluminum profile using a high-voltage electrostatic spraying method. The aluminum plate was baked at 200℃ for 10min to completely cure it.

[0033] Table 2

[0034]

[0035]

[0036] In Table 2: E-12 is a bisphenol A type epoxy resin produced by Anhui Meijia New Material Co., Ltd.; SA2830 is a superfine dicyandiamide type curing agent produced by Lu'an Jetuodaxin Material Co., Ltd.; SA88 is a leveling agent produced by Lu'an Jetuodaxin Material Co., Ltd.; PV88PV88 is a leveling agent produced by ESTRON, USA, and the specific model is Resiflow PV-88; MA-100 is carbon black produced by Mitsubishi Chemical Corporation; silicon powder is micro silicon powder 951 produced by Eken Organic Silicon Co., Ltd.; K7005 is a high-temperature resistant additive produced by Lu'an Jetuodaxin Material Co., Ltd.

[0037] The specific test standards and methods are as follows:

[0038] Gloss: WGG60-E4 gloss meter was used to measure the gloss at 60°;

[0039] Film thickness: A-3430 film thickness gauge of Germany BYK company was used for measurement;

[0040] Leveling performance: according to the leveling effect rating standard plate of American PCI, 1 is poor and 10 is excellent;

[0041] Impact performance: Kunshan Sanuo instrument paint film impact instrument QCJ-1m was used to determine according to GB / T 1732-93. The height of crack, wrinkle, peeling and other phenomena of the positive and negative impact of the paint film was observed and evaluated;

[0042] High heat resistance: the coating plate prepared by the application was baked in a muffle furnace at 350℃ for 4h, and the coating was observed for cracking;

[0043] The test results are shown in Table 3:

[0044] Table 3

[0045]

[0046] From the test results in Table 3, it can be seen that application examples 1-4 have little difference in gloss, film thickness and leveling performance compared with comparative application example 1, but have obvious advantages in impact performance and high heat resistance.

[0047] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting; it is not intended to exclude myriad other embodiments of the present application that other inventors can develop based on the same general inventive concepts embodied by the described embodiments. That is, although the present application is described in terms of particular embodiments and illustrative figures, it should be apparent that the scope of the present application is not limited to these specific embodiments.

[0048] While the embodiments of the application have been shown and described herein, it will be understood by those skilled in the art that many changes, modifications, substitutions and alterations to these embodiments can be made without departing from the principles and spirits of the application, and it is intended that the scope of the application be limited solely by the scope of the appended claims and the equivalents thereof.

Claims

1. A high heat-resistant carboxyl type acrylic resin for powder coating, characterized by, The raw materials include the following weight percentages: vinyl polysilsesquioxane 5-10%, (meth)acrylic acid monomer 20-25%, (meth)acrylic alkyl ester monomer 50-55%, dimethylaminoethyl methacrylate 5-10%, styrene-based monomer 10-20%, first initiator 2-5%, second initiator 0.2-0.5%, curing accelerator 0.1-1%, and the sum of the weight percentages of the raw materials is equal to 100%; The weight average molecular weight of the high-heat-resistant carboxyl type acrylic resin for powder coating is 10,000-20,000. The curing accelerator is any one of an imidazole type curing accelerator and a quaternary phosphonium salt type curing accelerator.

2. The high heat-resistant carboxyl type acrylic resin for powder coating according to claim 1, characterized by, The vinyl polysilsesquioxane is any one of a mono-vinyl cage type polysilsesquioxane and a multi-vinyl cage type polysilsesquioxane.

3. The high heat-resistant carboxyl type acrylic resin for powder coating according to claim 1, characterized by, The (meth)acrylic acid monomer is any one of methacrylic acid and acrylic acid.

4. The high heat-resistant carboxyl type acrylic resin for powder coating according to claim 1, characterized by, The (meth)acrylic alkyl ester monomer is any one or more of the following mixed in any ratio: methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, isobutyl acrylate, tert-butyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, octadecyl acrylate, cyclohexyl acrylate, isobornyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, tert-butyl methacrylate, isobutyl methacrylate, 2-ethylhexyl methacrylate, dodecyl methacrylate, octadecyl methacrylate, cyclohexyl methacrylate, and isobornyl methacrylate.

5. The high heat-resistant carboxyl type acrylic resin for powder coating according to claim 1, characterized by, The styrene-based monomer is any one of the following: methylstyrene, dimethylstyrene, trimethylstyrene, ethylstyrene, diethylstyrene, triethylstyrene, propylstyrene, butylstyrene, hexylstyrene, heptylstyrene, and octylstyrene.

6. The high heat-resistant carboxyl type acrylic resin for powder coating according to claim 1, characterized by, The first initiator and the second initiator are any one of 2,2'-azobis(isobutyronitrile) and benzoyl peroxide.

7. The synthesis method of a high heat-resistant carboxyl type acrylic resin for powder coatings according to claim 1, characterized in that, The method specifically comprises the following steps: Step one: a free radical polymerization solvent is added to a reaction container, and the mixture of vinyl polysilsesquioxane, (meth)acrylic acid monomer, (meth)acrylic alkyl ester monomer, dimethylaminoethyl methacrylate, styrene-based monomer, and first initiator is stirred and heated to a reflux state, and the mixture is added dropwise to the refluxing solvent within 3-3.5 hours, and after the dropwise addition is completed, the mixture is refluxed for 2 hours, and a mixture of the second initiator and the free radical polymerization solvent is added dropwise within 10 minutes, and then the mixture is refluxed for 2 hours; Step two: after the refluxing reaction is completed, the curing accelerator is added, and the solvent is removed by distillation, and when the temperature of the reaction system reaches 180°C, the reaction is carried out under a vacuum degree of -0.09 MPa for 0.5 hours, and after the reaction is completed, the vacuum is released, and the product is cooled to obtain the high-heat-resistant carboxyl type acrylic resin for powder coating.

8. The synthesis method of a high heat-resistant carboxyl type acrylic resin for powder coatings according to claim 7, characterized by, The radical polymerization solvent is any one or more of toluene, xylene, butyl acetate, ethyl acetate mixed in any ratio; the total mass of the radical polymerization solvent in step one is 90-100% of the total weight of the raw materials, and the mass ratio of the second initiator to the radical polymerization solvent in the mixed solution of the second initiator and the radical polymerization solvent is 1:

20.

9. The synthesis method of a high heat-resistant carboxyl type acrylic resin for powder coatings according to claim 7, characterized by, The Tg of the carboxyl type acrylic resin is 50-80℃, the weight average molecular weight is 10000-20000, and the molecular weight distribution is 1.8-2.2.

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