Non-organosilicone superhard wear-resistant low-cost high-gloss water-based baking varnish and preparation method thereof

Abstract

According to the non-organosilicone superhard wear-resistant low-cost high-gloss water-based stoving varnish and the preparation method thereof, the low-cost high-TG acrylic emulsion and the methylated amino resin are subjected to a cross-linking reaction under the action of the closed curing agent to form a cross-linked network, the low-melting-point glass powder is wrapped with the modified epoxy emulsion, and the non-organosilicone superhard wear-resistant low-cost high-gloss water-based stoving varnish is prepared. And filling pores and defects in the coating, and meanwhile, forming a protective layer on the surface. The water-based baking varnish product with the performance similar to or better than that of a commercially available organic silicon baking varnish product can be prepared while the cost is reduced, high baking temperature is not needed, the risk of potential heat damage to a heat-sensitive base material is greatly reduced, and the service life of the water-based baking varnish product is prolonged. And the application range of the water-based baking varnish product in cost-sensitive markets such as middle and low-end household appliances, kitchen and bathroom facilities, hardware tools and the like is expanded.

Description

[Technical field]

[0001] The invention belongs to the technical field of coating materials, and in particular relates to a non-silicone super-hard, wear-resistant, low-cost, high-gloss water-based baking varnish and a preparation method thereof. [Background technology]

[0002] Baking varnish is a coating that is cured by high-temperature baking and is widely used on substrate surfaces to provide protection and decorative effects. According to the type of film-forming substance, baking varnish can be divided into silicone baking varnish and non-silicone baking varnish. Silicone baking varnish is known for its excellent hardness, wear resistance, high temperature resistance, chemical resistance and electrical insulation, but the synthesis and processing costs are relatively high. Although non-silicone baking varnish uses lower-cost resin as a film-forming substance and its baking temperature is relatively low, the product hardness and wear resistance are far inferior to silicone baking varnish.

[0003] At present, in order to prepare paint products with a hardness of 5H or above and resistant to violent scratches, the industry often uses silicone resin as the main film-forming substance. However, the high cost of silicone resin limits the application of paint products in cost-sensitive markets such as mid- and low-end home appliances, kitchen and bathroom facilities, and hardware tools. In addition, silicone paint usually needs to be baked at a high temperature for a long time to achieve complete curing and achieve the required hardness. This not only increases energy consumption and production costs, but may also cause potential thermal damage to heat-sensitive substrates. [Summary of the invention]

[0004] The purpose of the present invention is to provide a non-silicone super-hard wear-resistant low-cost high-gloss water-based baking varnish to solve the problems of high cost of current silicone baking varnish products and high baking temperature, which easily causes thermal damage to the substrate.

[0005] A non-silicone super-hard wear-resistant low-cost high-gloss water-based baking varnish, comprising the following components by weight:

[0006]

[0007] Specifically, the polymer chain segments of high TG acrylic emulsion can be arranged more closely at room temperature, and it has a high glass transition temperature, which can achieve the effect of high hardness and low film-forming temperature. Methylated amino resin is a water-soluble resin, which has higher hardness and better flexibility when cured than silicone resin. At the same time, the methoxymethyl group in the methylated amino resin can undergo ether exchange with the hydroxyl group in the acrylic emulsion to form a stable chemical bond.

[0008] The invention forms a cross-linked network by cross-linking reaction between high TG acrylic emulsion and methyl etherified amino resin under the action of a blocked curing agent; forms a dense glass network by ceramicizing low melting point glass powder at a temperature above 150°C, thereby filling pores and defects in the coating and further improving the hardness, wear resistance and glossiness of the coating; uses modified epoxy emulsion to wrap the low melting point glass powder, utilizes the flexibility of the epoxy emulsion to prevent excessive embrittlement of the paint, forms a coating on the surface of the paint by the modified epoxy emulsion, thereby improving the anti-fouling and anti-scratch properties of the coating, and comprehensively optimizes the comprehensive performance of the baking varnish by adding various additives and curing agents.

[0009] Preferably, the modified epoxy emulsion is a fluorine-modified macromolecular epoxy emulsion.

[0010] The present invention adopts fluorine-modified macromolecular epoxy emulsion. During the baking process, fluorine molecules will slowly migrate to the surface of the paint to form a coating containing fluorine molecules. Fluorine atoms have extremely low surface energy, so that the surface of the coating has good hydrophobicity and oleophobicity, thereby significantly improving the anti-fouling performance of the coating. In addition, the fluorine atoms of the fluorine-modified macromolecular epoxy emulsion can combine with epoxy resin to significantly enhance the anti-scratch performance of the coating.

[0011] Preferably, the method for preparing the fluorine-modified macromolecular epoxy emulsion comprises the following steps:

[0012] A1. Pretreatment: Add macromolecular epoxy resin into the reaction vessel and heat it to 60°C;

[0013] A2, polymerization reaction: after the epoxy resin in step A1 is heated, add fluorine-containing monomer and stir for 30 minutes to obtain fluorine-modified epoxy resin;

[0014] A3. Emulsification: The fluorine-modified epoxy resin described in step A2 is kept warm for 2 hours and then cooled to room temperature, an emulsifier is added, and stirred for 20 minutes to obtain a fluorine-modified macromolecular epoxy emulsion.

[0015] The present invention changes the surface properties and chemical properties of the epoxy resin by introducing fluorine atoms. Through the action of an emulsifier, the fluorine-modified epoxy resin can be converted into a stable emulsion form, thereby improving the subsequent compatibility of the modified epoxy emulsion with other components and improving its dispersibility in the paint, which helps to improve the comprehensive performance of the baking varnish.

[0016] Preferably, the blocked curing agent is a polyisocyanate blocked curing agent.

[0017] The present invention adopts polyisocyanate as the main component of the curing agent, which can coexist stably with the water-based resin for a long time at room temperature. When the temperature rises to above 105°C, the curing agent begins to unblock and release active isocyanate groups. These active groups preferentially undergo cross-linking reactions with the hydroxyl groups in the high TG acrylic emulsion to form a dense network structure, thereby significantly improving the hardness, wear resistance and chemical resistance of the baking varnish.

[0018] Preferably, the thickener is a polyurethane thickener.

[0019] The present invention adopts a polyurethane thickener, which can form an associative network structure in the coating through its special molecular structure, thereby effectively adjusting the viscosity of the coating system.

[0020] Another object of the present invention is to provide a method for preparing a non-silicone super-hard, wear-resistant, low-cost, high-gloss water-based baking varnish.

[0021] The preparation method of the non-organic silicon super-hard wear-resistant low-cost high-gloss water-based baking varnish comprises the following steps:

[0022] S1. Pretreatment: adding the modified epoxy emulsion into a reaction container, stirring, slowly adding the low-melting-point glass powder, stirring, until the modified epoxy emulsion fully infiltrates and completely wraps the low-melting-point glass powder, to obtain a pretreated product;

[0023] S2, preparing the main paint: adding high TG acrylic emulsion and methyl etherified amino resin into a high-speed dispersion tank, stirring until the two are evenly mixed, adding the pretreated material described in step S1, and continuing to stir until the dispersion is evenly dispersed to obtain a mixture;

[0024] S3, mixing: sequentially adding a wetting agent, a dispersant, a defoaming agent, a cooling agent, a film-forming aid, a flexibilizer and pure water to the mixture in step S2, stirring, then adding a blocked curing agent, stirring, adding a thickener, adjusting the viscosity, and obtaining a non-silicone super-hard, wear-resistant, low-cost, high-gloss water-based paint.

[0025] The preparation method of the non-silicone super-hard wear-resistant low-cost high-gloss water-based baking varnish of the present invention comprises the following steps: firstly, pre-treating the glass powder, stirring and infiltrating the glass powder with a modified epoxy emulsion, so that the surface of the glass powder is completely wrapped by the epoxy emulsion, hydrogen bonds or chemical bonds are formed between the polar groups of the epoxy emulsion and the surface of the glass powder to enhance the interface bonding, and the rigidity of the glass powder is buffered by the flexibility of the epoxy emulsion to avoid subsequent crushing or sedimentation of the glass powder, thereby improving the dispersibility of the glass powder in the paint and preventing the glass powder from physically interfering with the acrylic resin too early, thereby laying a foundation for the subsequent formation of a dense glass structure and a surface protective layer, combining the film-forming resin with the pre-treated material, forming a preliminary cross-linking network in the cooperation of the methyl etherified amino resin to obtain the main paint, and then adding additives such as a wetting agent and a dispersant in steps to avoid interference between components, and finally introducing a closed curing agent to comprehensively optimize the hardness, wear resistance and glossiness of the coating.

[0026] Preferably, the viscosity range of step S3 is 2500-4500 CPS.

[0027] The present invention adopts a thickener to adjust the viscosity of the baking paint. 2500-4500 CPS helps the baking paint to form a uniform atomization effect during the spraying process, so that the baking paint can flow levelly on the surface of the substrate, and the defects of the coating film can be reduced.

[0028] The non-silicone super-hard, wear-resistant, low-cost, high-gloss water-based baking varnish of the present invention forms a cross-linked network through a cross-linking reaction between a high-TG acrylic emulsion and a methyl etherified amino resin under the action of a blocked curing agent, and wraps a low-melting-point glass powder with a modified epoxy emulsion to fill pores and defects in the coating, while forming a protective layer on the surface, thereby improving the hardness, wear resistance and glossiness of the baking varnish.

[0029] The method for preparing the non-silicone super-hard, wear-resistant, low-cost, high-gloss water-based baking varnish of the present invention ensures the compatibility and dispersibility of the epoxy emulsion and the glass powder through pretreatment, laying the foundation for the subsequent formation of a dense glass structure and a surface protective layer, and obtains the main paint by combining the film-forming resin with the pretreated material, and then comprehensively optimizes the comprehensive performance of the baking varnish by adding various additives and curing agents. [Specific implementation method]

[0030] The specific technical scheme of the present invention is described below in conjunction with Examples 1-3:

[0031] The preparation method of fluorine-modified macromolecular epoxy emulsion comprises the following steps:

[0032] A1. Pretreatment: Add 85 parts of macromolecular epoxy resin into a reaction vessel and heat it to 60°C;

[0033] A2, polymerization reaction: after the epoxy resin in step A1 is heated, 10 parts of fluorine-containing monomer are added and stirred for 30 minutes to obtain a fluorine-modified epoxy resin;

[0034] A3. Emulsification: The fluorine-modified epoxy resin described in step A2 is kept warm for 2 hours and then cooled to room temperature, 5 parts of emulsifier is added, and stirred for 20 minutes to obtain a fluorine-modified macromolecular epoxy emulsion.

[0035] Embodiment 1:

[0036] The preparation method of the non-organic silicon super-hard wear-resistant low-cost high-gloss water-based baking varnish comprises the following steps:

[0037] S1. Pretreatment: 8 parts of fluorine-modified macromolecular epoxy emulsion are added to a reaction container, stirred, and 9 parts of low-melting-point glass powder are slowly added, stirred until the fluorine-modified macromolecular epoxy emulsion fully infiltrates and completely wraps the low-melting-point glass powder to obtain a pretreated product;

[0038] S2. Prepare the main paint: add 48 parts of high TG acrylic emulsion and 15 parts of methyl etherified amino resin into a high-speed dispersion tank, stir until the two are evenly mixed, add the pretreated material described in step S1, continue stirring until the dispersion is evenly dispersed, and obtain a mixture;

[0039] S3, mixing: add 0.3 parts of wetting agent, 0.2 parts of dispersant, 0.2 parts of defoaming agent, 0.5 parts of cooling agent, 5 parts of film-forming aid, 1 part of flexibilizer and 8.6 parts of pure water to the mixture in step S2 in sequence, stir, then add 5 parts of blocked curing agent, stir, add 1 part of thickener, adjust the viscosity, and obtain non-silicone super-hard wear-resistant low-cost high-gloss water-based baking varnish.

[0040] Embodiment 2:

[0041] The preparation method of the non-silicone super-hard wear-resistant low-cost high-gloss water-based baking varnish comprises the following steps:

[0042] S1. Pretreatment: 8 parts of fluorine-modified macromolecular epoxy emulsion are added to a reaction container, stirred, and 7 parts of low-melting-point glass powder are slowly added, stirred until the fluorine-modified macromolecular epoxy emulsion fully infiltrates and completely wraps the low-melting-point glass powder to obtain a pretreated product;

[0043] S2, preparing the main paint: adding 50 parts of high TG acrylic emulsion and 15 parts of methyl etherified amino resin into a high-speed dispersion tank, stirring until the two are evenly mixed, adding the pretreated material described in step S1, and continuing to stir until the dispersion is evenly dispersed to obtain a mixture;

[0044] S3, mixing: add 0.3 parts of wetting agent, 0.2 parts of dispersant, 0.2 parts of defoaming agent, 0.5 parts of cooling agent, 5 parts of film-forming aid, 1 part of flexibilizer and 6.8 parts of pure water to the mixture in step S2 in sequence, stir, then add 5 parts of blocked curing agent, stir, add 1 part of thickener, adjust the viscosity, and obtain non-silicone super-hard wear-resistant low-cost high-gloss water-based baking varnish.

[0045] Embodiment 3:

[0046] The preparation method of the non-organic silicon super-hard wear-resistant low-cost high-gloss water-based baking varnish comprises the following steps:

[0047] S1. Pretreatment: 8 parts of fluorine-modified macromolecular epoxy emulsion are added to a reaction container, stirred, and 5 parts of low-melting-point glass powder are slowly added, stirred until the fluorine-modified macromolecular epoxy emulsion fully infiltrates and completely wraps the low-melting-point glass powder to obtain a pretreated product;

[0048] S2. Prepare the main paint: add 55 parts of high TG acrylic emulsion and 15 parts of methyl etherified amino resin into a high-speed dispersion tank, stir until the two are evenly mixed, add the pretreated material described in step S1, continue stirring until the dispersion is evenly dispersed, and obtain a mixture;

[0049] S3, mixing: add 0.3 parts of wetting agent, 0.2 parts of dispersant, 0.2 parts of defoaming agent, 0.5 parts of cooling agent, 5 parts of film-forming aid, 1 part of flexibilizer and 5.6 parts of pure water to the mixture in step S2 in sequence, stir, then add 5 parts of blocked curing agent, stir, add 1 part of thickener, adjust the viscosity, and obtain non-silicone super-hard wear-resistant low-cost high-gloss water-based baking varnish.

[0050] Comparative Example 1:

[0051] The preparation method of the non-organic silicon super-hard wear-resistant low-cost high-gloss water-based baking varnish comprises the following steps:

[0052] S1. Prepare the main paint: add 45 parts of high TG acrylic emulsion and 15 parts of methyl etherified amino resin into a high-speed dispersion tank, stir until the two are evenly mixed, slowly add 15 parts of low melting point glass powder, continue stirring until the dispersion is evenly dispersed to obtain a mixture;

[0053] S2, mixing: add 0.3 parts of wetting agent, 0.2 parts of dispersant, 0.2 parts of defoaming agent, 0.5 parts of cooling agent, 5 parts of film-forming aid, 1 part of flexibilizer and 10.6 parts of pure water to the mixture in step S2 in sequence, stir, then add 8 parts of blocked curing agent, stir, add 1 part of thickener, adjust the viscosity, and obtain non-silicone super-hard wear-resistant low-cost high-gloss water-based baking varnish.

[0054] Comparative Example 2:

[0055] The preparation method of the non-organic silicon super-hard wear-resistant low-cost high-gloss water-based baking varnish comprises the following steps:

[0056] S1. Prepare the main paint: add 45 parts of high TG acrylic emulsion and 15 parts of methyl etherified amino resin into a high-speed dispersion tank, stir until the two are evenly mixed, add 15 parts of fluorine-modified macromolecular epoxy emulsion, continue stirring until the dispersion is evenly dispersed to obtain a mixture;

[0057] S2, mixing: add 0.3 parts of wetting agent, 0.2 parts of dispersant, 0.2 parts of defoaming agent, 0.5 parts of cooling agent, 5 parts of film-forming aid, 1 part of flexibilizer and 8.6 parts of pure water to the mixture in step S2 in sequence, stir, then add 5 parts of blocked curing agent, stir, add 1 part of thickener, adjust the viscosity, and obtain non-silicone super-hard wear-resistant low-cost high-gloss water-based baking varnish.

[0058] Comparative Example 3:

[0059] The preparation method of the non-organic silicon super-hard wear-resistant low-cost high-gloss water-based baking varnish comprises the following steps:

[0060] S1. Prepare the main paint: add 60 parts of high TG acrylic emulsion and 20 parts of methyl etherified amino resin into a high-speed dispersion tank, and stir until the two are evenly mixed to obtain a mixture;

[0061] S2, mixing: add 0.3 parts of wetting agent, 0.2 parts of dispersant, 0.2 parts of defoaming agent, 0.5 parts of cooling agent, 5 parts of film-forming aid, 1 part of flexibilizer and 8.6 parts of pure water to the mixture in step S2 in sequence, stir, then add 5 parts of blocked curing agent, stir, add 1 part of thickener, adjust the viscosity, and obtain non-silicone super-hard wear-resistant low-cost high-gloss water-based baking varnish.

[0062] Comparative Example 4:

[0063] Comparative Example 4 is a commercially available silicone baking varnish product having a hardness of 5H or more.

[0064] Table 1 Components of Examples 1-3 and Comparative Examples 1-3

[0065]

[0066]

[0067] The baking varnishes of Examples 1-3 and Comparative Examples 1-3 were applied to the surface of a substrate, and were completely cured by baking at 160° C. for 30 minutes, and the performance of the coatings was tested.

[0068] The baking varnish of Comparative Example 4 was applied to the surface of a substrate and completely cured by baking at 220° C. for 30 minutes, and the performance of the coating was tested.

[0069] Table 2 Coating test data of Examples 1-3

[0070]

[0071]

[0072] Table 3 Coating test data of comparative examples 1-4

[0073]

[0074] As can be seen from Table 2, the coatings of Examples 1-3 have a smooth and flat appearance, and all have high solid content, high hardness, excellent gloss, good impact resistance, excellent chemical stability and anti-fouling properties.

[0075] It can be seen from Table 2 and Table 3 that compared with Examples 1-3, Comparative Example 1 without adding modified epoxy emulsion and Comparative Example 2 without adding glass powder have lower solid content, hardness, impact resistance, and poor chemical stability and anti-fouling properties, while Comparative Example 3 without adding modified epoxy emulsion and glass powder has lower solid content, hardness, and poorer impact resistance, anti-fouling properties and chemical stability.

[0076] Compared with the commercially available silicone baking varnish product of Comparative Example 4 baked at 220° C., Examples 1-3 baked at 160° C. have higher solid content and hardness, and better impact resistance and anti-fouling properties.

[0077] The non-organic silicon super-hard wear-resistant low-cost high-gloss water-based paint of the present invention uses a low-cost high-TG acrylic emulsion and a methyl etherified amino resin to undergo a cross-linking reaction under the action of a blocked curing agent to form a cross-linked network, and a low-melting-point glass powder is wrapped by a modified epoxy emulsion to fill the pores and defects in the coating, and a protective layer is formed on the surface to improve the hardness, wear resistance and glossiness of the paint. While reducing costs, a water-based paint product with similar or better performance than commercially available silicone paint products can be prepared, and a higher baking temperature is not required, which greatly reduces the risk of potential thermal damage to heat-sensitive substrates and expands the application of water-based paint products in cost-sensitive markets such as mid- and low-end home appliances, kitchen and bathroom facilities, and hardware tools.

[0078] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A non-silicone super-hard wear-resistant low-cost high-gloss water-based paint, characterized by: By weight, it includes the following components:

2. According to claim 1, the non-silicone super-hard wear-resistant low-cost high-gloss water-based paint is characterized by: The modified epoxy emulsion is a fluorine-modified macromolecular epoxy emulsion.

3. The non-silicone super-hard wear-resistant low-cost high-gloss water-based paint according to claim 2 is characterized by: The preparation method of the fluorine-modified macromolecular epoxy emulsion comprises the following steps: A1. Pretreatment: Add macromolecular epoxy resin into the reaction vessel and heat it to 60°C; A2, polymerization reaction: after the epoxy resin in step A1 is heated, add fluorine-containing monomer and stir for 30 minutes to obtain fluorine-modified epoxy resin; A3. Emulsification: The fluorine-modified epoxy resin described in step A2 is kept warm for 2 hours and then cooled to room temperature, an emulsifier is added, and stirred for 20 minutes to obtain a fluorine-modified macromolecular epoxy emulsion.

4. The non-silicone super-hard wear-resistant low-cost high-gloss water-based paint according to claim 1, characterized in that: The blocked curing agent is a polyisocyanate blocked curing agent.

5. The non-silicone super-hard wear-resistant low-cost high-gloss water-based paint according to claim 1, characterized in that: The thickener is a polyurethane thickener.

6. The method for preparing the non-silicone super-hard wear-resistant low-cost high-gloss water-based baking varnish according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1. Pretreatment: adding the modified epoxy emulsion into a reaction container, stirring, slowly adding the low-melting-point glass powder, stirring, until the modified epoxy emulsion fully infiltrates and completely wraps the low-melting-point glass powder, to obtain a pretreated product; S2, preparing the main paint: adding high TG acrylic emulsion and methyl etherified amino resin into a high-speed dispersion tank, stirring until the two are evenly mixed, adding the pretreated material described in step S1, and continuing to stir until the dispersion is evenly dispersed to obtain a mixture; S3, mixing: sequentially adding a wetting agent, a dispersant, a defoaming agent, a cooling agent, a film-forming aid, a flexibilizer and pure water to the mixture in step S2, stirring, then adding a blocked curing agent, stirring, adding a thickener, adjusting the viscosity, and obtaining a non-silicone super-hard, wear-resistant, low-cost, high-gloss water-based paint.

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