Ultra-fast-drying acrylic resin for automobile coating and preparation method of ultra-fast-drying acrylic resin

Abstract

The invention belongs to the field of automobile coatings, and particularly relates to an ultra-fast-drying acrylic resin for an automobile coating and a preparation method of the ultra-fast-drying acrylic resin for the automobile coating, and the ultra-fast-drying acrylic resin for the automobile coating comprises the following components in parts by weight: 25-35 parts of an organic solvent; 5 to 15 parts of methyl methacrylate; 5 to 15 parts of isobornyl methacrylate; 25 to 35 parts of styrene; 5 to 15 parts of tert-butyl acrylate; 10 to 20 parts of hydroxyethyl methylacrylate; 1-5 parts of a ureido functional acrylate monomer; and 2-6 parts of an initiator. By introducing the ureido functional acrylate monomer, the cross-linking speed of the hydroxy acrylic resin and the isocyanate curing agent can be remarkably improved, and the drying time of a coating film is shortened.

Description

Technical Field

[0001] This invention belongs to the field of automotive coatings, specifically relating to an ultra-fast drying acrylic resin for automotive coatings and its preparation method. Background Technology

[0002] With the continuous growth of car ownership in my country, the demand for automotive coatings is increasingly strong. In the automotive repair process, clear coat, as a key coating that determines the final appearance and performance, directly affects the repair efficiency due to its drying speed. Currently, the mainstream system is a two-component coating composed of hydroxyl acrylic resin and polyisocyanate curing agent. However, ordinary clear coats usually need to be baked at 60-80℃ for 30-60 minutes, or dried at room temperature for more than 12 hours, before subsequent polishing can be carried out. This is not only inefficient but also wastes energy.

[0003] The market's increasing demands for fast-paced service and environmental protection have driven the demand for ultra-fast drying clear coats. Ideally, clear coats should combine rapid drying with excellent appearance; however, traditional domestic clear coats often struggle to achieve both. Rapid drying results in poor leveling, insufficient gloss, and inadequate fullness. Conversely, good appearance often comes at the cost of slow drying. In recent years, to improve repair shop productivity and shorten delivery cycles, the industry has urgently needed an ultra-fast drying clear coat that can achieve initial drying in a lower temperature environment while simultaneously ensuring a superior paint film appearance. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide an ultra-fast drying acrylic resin for automotive coatings and its preparation method. The present invention introduces urea-functionalized acrylate monomers, which can significantly improve the crosslinking speed of hydroxy acrylic resin and isocyanate curing agents and shorten the drying time of the coating film.

[0005] The technical solution adopted by the present invention to solve the above problems is as follows: An ultra-fast drying acrylic resin for automotive coatings comprises the following components in parts by weight: 25-35 parts organic solvent; 5-15 parts methyl methacrylate; 5-15 parts isobornyl methacrylate; 25-35 parts styrene; 5-15 parts tert-butyl acrylate; 10-20 parts hydroxyethyl methacrylate; 1-5 parts urea-functionalized acrylate monomer; and 2-6 parts initiator.

[0006] By introducing urea-functionalized acrylate monomers through the above technical solutions, the crosslinking and curing speed of hydroxyl acrylic resins and isocyanate curing agents can be significantly improved, enabling rapid crosslinking of the paint film at low temperatures, shortening the drying time of the coating, and thus shortening the coating cycle. At the same time, it can maintain the fullness and leveling properties of the paint film, significantly improving construction efficiency and reducing energy consumption and production costs while ensuring excellent coating results.

[0007] Further, the urea-functionalized acrylate monomer comprises 15 parts of N-hydroxyethylvinylurea; 12 parts of acrylic acid; 1-3 parts of catalyst; 0.1-0.5 parts of polymerization inhibitor; and 30 parts of toluene.

[0008] Furthermore, the preparation method of the urea-functionalized acrylate monomer includes the following steps: S1. Mix N-hydroxyethylvinylurea and acrylic acid, then add catalyst, polymerization inhibitor and toluene, and react at 110-120℃ for 4-8 hours until the theoretical acid value drops below 5 mgKOH / g to obtain material 1; S2. Cool material 1 to room temperature, reduce pressure to 0.09-0.095 MPa and heat to 80-90°C to remove toluene by distillation, and collect the urea-functionalized acrylate monomer.

[0009] Furthermore, the catalyst is p-toluenesulfonic acid.

[0010] Furthermore, the polymerization inhibitor is hydroquinone.

[0011] Furthermore, the initiator is di-tert-amyl peroxide.

[0012] The above-described initiation process of di-tert-amyl peroxide is stable, with moderate free radical activity, resulting in a more regular polymer molecular chain structure and controllable branching degree. These advantages directly translate into improvements in the mechanical properties, solvent release (initial drying speed, actual drying speed), and thermal stability of the finished product, meeting the requirements of ultra-fast drying applications in high-end automotive coatings.

[0013] Furthermore, the organic solvent is n-butyl acetate.

[0014] The present invention also provides a method for preparing the above-mentioned ultra-fast drying acrylic resin for automotive coatings, comprising the following steps: A1. Nitrogen gas is introduced into the reactor, and then 90% of the formula amount of organic solvent is added. The mixture is stirred at a speed of 40-50 r / min, and then heated to 124-126℃ for reflux and kept at that temperature for 20-30 min. The reactor is then sealed and heated to 160-165℃ and kept at that temperature to obtain material 1. A2. Mix methyl methacrylate, isobornyl methacrylate, styrene, tert-butyl acrylate, hydroxyethyl methacrylate, urea-functionalized acrylate monomer, and 80% of the initiator in the formulation, and stir at a speed of 40-50 r / min for 15-20 min to obtain material 2. A3. Add material 2 to material 1 at a uniform rate, and the adding time is less than or equal to 4.5 hours. After the adding is completed, keep it warm for 4 to 5 hours to obtain material 3. A4. Add the remaining organic solvent and initiator to material 3, keep warm for 4-5 hours, then cool down to 90°C and depressurize to atmospheric pressure, then filter to obtain the finished product.

[0015] The present invention has the following beneficial effects: 1. This invention, by introducing urea-functionalized acrylate monomers, significantly improves the crosslinking speed of hydroxyl acrylic resins and isocyanate curing agents, shortening the drying time of the coating film. The urea-functionalized acrylate monomers are obtained through esterification of the carboxyl group of acrylic acid with the hydroxyl group of N-hydroxyethylvinyl urea. The monomer structure contains not only an acrylate double bond that can participate in the copolymerization of acrylic monomers, but also a rigid cyclic urea group. The secondary amine and carbon groups in the cyclic urea group can form a strong hydrogen bond network with other polar groups in the resin, constructing dense physical crosslinking points in the coating film, thereby rapidly improving initial hardness and drying speed. The hydroxyl acrylic resin prepared using this invention, supplemented with HDI trimer curing agent, diluent, and leveling agent, can be formulated into an ultra-fast-drying clear coat, achieving rapid surface and complete drying at 25°C. This allows for rapid polishing of vehicles, significantly improving construction efficiency and shortening the painting and delivery cycle.

[0016] 2. N-hydroxyethylvinylurea raw material is stable and has high reaction selectivity, which can avoid the occurrence of side reactions, thereby significantly improving the yield and final quality of monomer synthesis. Detailed Implementation

[0017] To make the technical problems, solutions, and advantages of this invention clearer, a detailed description will be provided below with reference to specific examples. However, the scope of protection of this invention is not limited to the following specific embodiments. The described embodiments are merely some, not all, of the embodiments of this invention, and are not intended to limit the invention. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0018] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0019] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0020] In the quantitative experiments in the following examples, three replicate experiments were set up, and the data are the average of the three replicate experiments or the average ± standard deviation.

[0021] The present invention includes Examples 1 to 5 and Comparative Example 1. The specific components and contents are shown in Table 1, and the units are parts by weight.

[0022] Table 1

[0023] The urea-functionalized acrylate monomer comprises: 15 parts N-hydroxyethylvinyl urea; 12 parts acrylic acid; 1.5 parts p-toluenesulfonic acid; 0.3 parts hydroquinone; and 30 parts toluene.

[0024] Specifically, the preparation method of the above-mentioned urea-functionalized acrylate monomer includes the following steps: S1. Mix N-hydroxyethyl vinyl urea and acrylic acid, then add p-toluenesulfonic acid, hydroquinone and toluene, and react at 110-120℃ for 4-8 hours until the theoretical acid value drops below 5 mg KOH / g to obtain material 1; S2. Cool material 1 to room temperature, reduce pressure to 0.095 MPa and heat to 90°C to remove toluene by distillation, and collect the urea-functionalized acrylate monomer.

[0025] Specifically, the preparation method of the above embodiments includes the following steps: A1. Nitrogen gas is introduced into the reactor, and then 90% of the organic solvent specified in the formula is added. The mixture is stirred at a speed of 40 r / min, then heated to 125℃ for reflux and held for 30 min. The reactor is then sealed and heated to 165℃ and held to obtain material 1. A2. Mix methyl methacrylate, isobornyl methacrylate, styrene, tert-butyl acrylate, hydroxyethyl methacrylate, urea-functionalized acrylate monomer, and initiator at 80% of the specified addition amount in the formula, and stir at 40 r / min for 20 min to obtain material 2; A3. Add material 2 to material 1 at a uniform rate, and the adding time is less than or equal to 4.5 hours. After the adding is completed, keep it warm for 4 hours to obtain material 3. A4. Add the remaining organic solvent and initiator to material 3, keep warm for 4 hours, then cool down to 90°C and depressurize to atmospheric pressure, then filter to obtain the finished product.

[0026] Similarly, the preparation method for the comparative proportion can be obtained. If there are substances that are not added or are removed, they can be removed in the corresponding preparation steps.

[0027] Testing and Inspection The hydroxyl acrylic resins prepared in Examples 1-5 and Comparative Example 1 were tested according to the following standards: Resin appearance inspection: GB / T1721; Color number inspection: GB / T1722; Acid value inspection: GB / T6743; Solid content inspection: GB / T1725; Viscosity inspection: ASTM D1545; Hydroxyl value inspection: GB / T31412.

[0028] The properties of the hydroxyl acrylic resins prepared in Examples 1-5 and Comparative Example 1 are shown in Table 2.

[0029] Table 2

[0030] Examples 1-5 and Comparative Example 1 were formulated into automotive clear coats and recorded as Examples 6-10 and Comparative Example 2. These were sprayed onto sanded tinplate materials and left to air dry in a 20°C room. The specific composition of the formulations is shown in Table 3.

[0031] Table 3

[0032] Performance tests were conducted on Examples 6-10 and Comparative Example 2. The performance tests were conducted according to the following standards: Paint film appearance test: Tested according to GB / T 9761-2008 "Visual colorimetric comparison of paints and varnishes"; Touch dry and finger-press dry tests: Tested according to GB / T 1728-2020; Hardness test: Tested according to GB / T6739-2022 "Determination of hardness of paint film by pencil method"; Gloss test: Tested according to GB / T9754. Specific test results are shown in Table 4.

[0033] Table 4

[0034] The test results of Examples 6-10 show that the ultra-fast drying acrylic resin of the present invention can balance the drying speed and performance of the paint film, significantly improve the drying efficiency, and the paint film has high gloss and high hardness.

[0035] By comparing the test results of Example 6 and Comparative Example 2, it can be seen that after using ordinary methacrylic resin instead of the urea-functional acrylate monomer prepared in this invention, the paint film performance of Comparative Example 2 is significantly weaker than that of Example 6 in terms of touch dry time, finger pressure dry time, and hardness. This indicates that the urea-functional acrylate monomer prepared in this invention has the effect of improving the drying speed and performance of the paint film.

[0036] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0037] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0038] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. An ultrafast-drying acrylic resin for automotive paints, characterized by comprising: The composition comprises the following components by weight parts: organic solvent 25-35 parts; methyl methacrylate 5-15 parts; isobornyl methacrylate 5-15 parts; styrene 25-35 parts; tert-butyl acrylate 5-15 parts; hydroxyethyl methacrylate 10-20 parts; urea-based functional acrylate monomer 1-5 parts; initiator 2-6 parts.

2. The ultrafast-drying acrylic resin for automotive paint according to claim 1, characterized by, The urea-based functional acrylate monomer comprises N-hydroxyethyl vinyl urea 15 parts; acrylic acid 12 parts; catalyst 1-3 parts; polymerization inhibitor 0.1-0.5 parts; toluene 30 parts.

3. The ultrafast-drying acrylic resin for automotive paint according to claim 2, characterized by, The preparation method of the urea-based functional acrylate monomer comprises the following steps: S1. Mix N-hydroxyethyl vinyl urea and acrylic acid, then add catalyst, polymerization inhibitor and toluene, and react at 110-120℃ for 4-8h until the theoretical acid value is reduced to below 5mgKOH / g to obtain material 1; S2. Cool material 1 to room temperature, reduce the pressure to 0.09-0.095MPa and heat to 80-90℃ for distillation to remove toluene, and collect the urea-based functional acrylate monomer.

4. The ultrafast drying acrylic resin for automotive paint according to claim 2, characterized by, The catalyst is p-toluenesulfonic acid.

5. The ultrafast drying acrylic resin for automotive paint according to claim 2, characterized by, The polymerization inhibitor is hydroquinone.

6. The ultrafast-drying acrylic resin for automotive paint according to claim 1, characterized by, The initiator is di-t-amyl peroxide.

7. The ultrafast-drying acrylic resin for automotive paint according to claim 1, characterized by, The organic solvent is n-butyl acetate.

8. A method for producing the ultrafast-drying acrylic resin for automotive paint according to any one of claims 1 to 7, characterized by, The method comprises the following steps: A1. Introduce nitrogen into the reaction kettle, then add 90% of the formula amount of organic solvent, stir at a speed of 40-50r / min, then heat to 124-126℃ for reflux and heat for 20-30min, heat the sealed reaction kettle to 160-165℃ and heat, to obtain material 1; A2. Mix methyl methacrylate, isobornyl methacrylate, styrene, tert-butyl acrylate, hydroxyethyl methacrylate, urea-based functional acrylate monomer, and 80% of the formula amount of initiator, stir at a speed of 40-50r / min for 15-20min to obtain material 2; A3. Uniformly drop material 2 into material 1, and the drop time is less than or equal to 4.5h, and heat for 4-5h after the drop is completed to obtain material 3; A4. Add the remaining organic solvent and initiator to material 3, heat for another 4-5h, then cool to 90℃ and release the pressure to normal pressure, and filter to obtain the finished product.

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