Water-based transparent peelable coating and preparation method thereof

Abstract

The invention belongs to the technical field of coatings, and discloses a water-based transparent peelable coating and a preparation method thereof. According to the coating, a modified acrylate copolymer emulsion with fluorine / siloxane chains embedded in molecules serves as a core film-forming substance. The coating comprises the following components in parts by weight: 50-80 parts of a modified acrylate copolymer emulsion with fluorine / siloxane chains embedded in molecules, 10-30 parts of deionized water, 0-5 parts of a coalescing agent, 0.1-0.5 part of a preservative and 0.1-0.3 part of a defoaming agent. Through the special structure of the emulsion, the coating is endowed with excellent peelability (complete peeling and no residue) and good transparency, the formula is simplified, the environmental protection property is good, the preparation process is simple, industrial production is easy, and the coating is suitable for temporary protection of various base materials.

Description

Technical Field

[0001] This invention relates to the field of coating technology, and more specifically to a water-based transparent peelable coating and its preparation method, particularly to a water-based transparent peelable coating with a modified acrylate copolymer emulsion with intramolecularly embedded fluorine / siloxane alkyl chains as the core film-forming substance. Background Technology

[0002] Peelable coatings, as a functional protective material, form a temporary protective film on the substrate surface, providing functions such as anti-fouling, anti-scratch, anti-rust, and anti-corrosion. After use, they can be completely and easily peeled off from the substrate surface without leaving any adhesive residue or damaging the substrate. They are widely used in metal processing, electronic components, automobile manufacturing, building decoration, and many other fields.

[0003] Currently, peelable coatings on the market are mainly divided into two categories: solvent-based and water-based. Although solvent-based peelable coatings have the characteristics of good film-forming properties and excellent peel performance, they contain a large amount of volatile organic solvents, which release toxic and harmful gases during production and use. This not only pollutes the environment but also endangers the health of operators, which is inconsistent with the current trend of green and environmentally friendly development.

[0004] Water-based peelable coatings, using water as the dispersion medium, offer advantages such as environmental friendliness, safety, and zero pollution, making them a research hotspot in the field of peelable coatings in recent years. However, existing water-based peelable coatings generally suffer from some drawbacks: on the one hand, to ensure the film-forming and peeling properties of the coating, a large number of additives, such as film-forming aids, plasticizers, and wetting and dispersing agents, need to be added to the formulation. The addition of these additives not only increases production costs but may also affect the transparency and storage stability of the coating. On the other hand, the peeling performance of existing water-based peelable coatings is limited by the properties of the film-forming substances, and some products suffer from problems such as difficulty in peeling and residual traces after peeling, making it difficult to meet the needs of high-end applications.

[0005] Therefore, developing a water-based peelable coating that does not require the addition of large amounts of additives, has good transparency, and excellent peeling performance has become a pressing technical problem to be solved in this field. Summary of the Invention

[0006] In view of this, and addressing the problems of existing water-based peelable coatings, such as the need for large amounts of additives, poor peelability, and compromised transparency, this invention provides a water-based transparent peelable coating and its preparation method. The core innovation of this invention lies in using a modified acrylate copolymer emulsion with intramolecularly embedded fluorine / siloxane alkyl chains as the core film-forming substance. This emulsion itself possesses additive functionality, eliminating the need for large amounts of additional additives, while significantly improving the coating's transparency and peelability, thus overcoming the shortcomings of existing technologies.

[0007] To achieve the above objectives, this invention provides a water-based, transparent, peelable coating, wherein the coating uses a modified acrylate copolymer emulsion with intramolecularly embedded fluorine / siloxane alkyl chains as the core film-forming substance. The modified acrylate copolymer emulsion with intramolecularly embedded fluorine / siloxane alkyl chains is a polymeric emulsion with built-in additive functions and is a key component for achieving the coating's transparency and peelability.

[0008] Furthermore, the preparation method of the modified acrylate copolymer emulsion with intramolecularly embedded fluorine / siloxane alkyl chains includes the following steps: S11 Pre-emulsification: By weight, add 20-40 parts of acrylate monomer, 5-15 parts of fluorinated monomer, 3-10 parts of monomer containing siloxane groups, 2-5 parts of emulsifier, and 20-40 parts of deionized water to a pre-emulsification tank, and stir for 30-60 minutes at 30-50℃ and a stirring speed of 200-400 r / min to obtain a pre-emulsion. Preparation of S12 seed emulsion: Add 50-80 parts of deionized water and 0.5-2 parts of emulsifier to the reaction vessel, heat to 70-80℃, add 10-20% of pre-emulsion and 0.1-0.5 parts of initiator, keep the reaction at the temperature for 30-60 minutes to obtain seed emulsion; S13 copolymerization reaction: The remaining pre-emulsion and 0.2-0.8 parts of initiator are slowly added dropwise to the reactor through a constant pressure dropping funnel. The dropping time is controlled at 2-4 hours, and the reaction temperature is maintained at 75-85℃ during the dropping process. After the dropping is completed, the reaction is continued to be kept at the temperature for 1-2 hours. S14 Post-processing: After the reaction is completed, the temperature is lowered to below 40℃, and the pH value of the system is adjusted to 7.0-8.0 with ammonia water. After filtration and discharge, a modified acrylate copolymer emulsion with intramolecularly embedded fluorine / siloxane alkyl chains is obtained.

[0009] Preferably, the acrylate monomer is selected from at least one of methyl methacrylate, ethyl acrylate, butyl acrylate, and butyl methacrylate; the fluorinated monomer is selected from at least one of fluorinated acrylate and fluorinated methacrylate; and the monomer containing a siloxane group is selected from at least one of γ-methacryloyloxypropyltrimethoxysilane and vinyltriethoxysilane.

[0010] Preferably, the emulsifier is a compound system of anionic and nonionic emulsifiers, wherein the anionic emulsifier is selected from at least one of sodium dodecylbenzenesulfonate and sodium dodecyl sulfate, and the nonionic emulsifier is selected from at least one of fatty alcohol polyoxyethylene ether and nonylphenol polyoxyethylene ether, and the weight ratio of anionic emulsifier to nonionic emulsifier is 1:1-3.

[0011] Preferably, the initiator is selected from at least one of ammonium persulfate and potassium persulfate.

[0012] Furthermore, the water-based transparent peelable coating comprises, by weight, the following components: 50-80 parts of modified acrylate copolymer emulsion with intramolecularly embedded fluorine / siloxane alkyl chains, 10-30 parts of deionized water, 0-5 parts of film-forming aid, 0.1-0.5 parts of preservative, and 0.1-0.3 parts of defoamer.

[0013] Preferably, the film-forming aid is selected from at least one of propylene glycol methyl ether acetate and ethylene glycol ethyl ether acetate; the preservative is selected from isothiazolinone preservatives; and the defoamer is selected from silicone defoamers.

[0014] Furthermore, the preparation method of the water-based transparent peelable coating includes the following steps: S21. Add the modified acrylate copolymer emulsion with intramolecularly embedded fluorine / siloxane alkyl chains into a stirred tank, turn on the stirrer, and stir at a speed of 150-250 r / min; S22. While stirring, slowly add deionized water and continue stirring for 10-20 minutes to ensure the system is mixed evenly; S23. Slowly add the film-forming aid dropwise into the stirred tank, and stir for 20-30 minutes after the addition is complete; S24. Add the preservative and defoamer in sequence and continue stirring for 30-40 minutes; S25. After stirring, the system is filtered through a 200-300 mesh filter to obtain a water-based transparent peelable coating.

[0015] The core innovation of this invention lies in the design and synthesis of a modified acrylate copolymer emulsion with intramolecularly embedded fluorine / siloxane alkyl chains as the core film-forming substance. This emulsion, by embedding fluorine / siloxane alkyl chains into the acrylate copolymer molecular chain, endows the copolymer with unique properties while simultaneously enabling the emulsion itself to possess the functions of additives in traditional coating formulations. The specific principle is as follows: 1. Realization of built-in additive function: Fluoro / siloxane alkyl chains have excellent surface activity, which can reduce the surface tension of emulsions and play a role in wetting and dispersing, equivalent to the wetting and dispersing agents in traditional coatings; at the same time, the introduction of fluoro / siloxane alkyl chains can improve the film-forming properties of copolymers, reduce film-forming temperature, reduce or even eliminate the need for additional film-forming aids, thereby simplifying coating formulations, reducing production costs, and avoiding the impact of additives on coating transparency.

[0016] 2. Achieving Excellent Peelability: Fluorine has extremely low surface energy, and siloxane chains possess excellent flexibility and lubricity. Embedding both into the acrylate copolymer molecular chain significantly reduces the surface energy of the coating after film formation, resulting in weaker interfacial forces between the coating and the substrate. This endows the coating with excellent peelability, ensuring easy, complete peeling without residue. This is the key to achieving the peelability of the coating in this invention; the core of the coating's peelability depends on the selection of this modified acrylate copolymer emulsion.

[0017] 3. Achievement of good transparency: The modified acrylic copolymer emulsion used in this invention has a uniform particle size distribution and a regular copolymer molecular chain structure. The coating formed after film formation is dense and uniform, with no obvious phase separation phenomenon, thereby ensuring that the coating has good transparency and can meet the use requirements of not affecting the appearance of the substrate.

[0018] As can be seen from the above technical solution, compared with the prior art, the beneficial effects achieved by the present invention are as follows: Simplified formulation and excellent environmental performance: The core film-forming emulsion has built-in auxiliary functions, eliminating the need to add large amounts of wetting and dispersing agents, film-forming aids, etc., reducing the amount of auxiliary materials used, lowering production costs, and avoiding environmental pollution caused by the volatilization of auxiliary materials, further improving the environmental performance of the coating. Excellent peeling performance: Relying on the unique structure of the modified acrylate copolymer with intramolecularly embedded fluorine / siloxane alkyl chains, the coating has low surface energy and weak interfacial force with the substrate, which can be easily and completely peeled off without residue. Good transparency: The emulsion has a uniform particle size, and the coating is dense and uniform after film formation, with high light transmittance, without affecting the original appearance of the substrate; The preparation process is simple: neither the emulsion synthesis nor the coating preparation process requires complex equipment or harsh reaction conditions, making it easy to industrialize. Detailed Implementation

[0019] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0020] Example 1 A water-based transparent peelable coating, by weight, comprises the following components: 60 parts of modified acrylate copolymer emulsion with intramolecularly embedded fluorine / siloxane alkyl chains, 20 parts of deionized water, 2 parts of film-forming aid (propylene glycol methyl ether acetate), 0.2 parts of preservative (isothiazolinone), and 0.1 parts of defoamer (organosilicon).

[0021] The preparation method of the above-mentioned modified acrylate copolymer emulsion with intramolecularly embedded fluorine / siloxane chains: 1. Pre-emulsification: By weight, 30 parts methyl methacrylate, 10 parts fluorinated acrylate, 5 parts γ-methacryloyloxypropyltrimethoxysilane, 2 parts sodium dodecylbenzenesulfonate, 4 parts fatty alcohol polyoxyethylene ether, and 30 parts deionized water are added to a pre-emulsification tank and stirred for 40 minutes at 40°C and a stirring rate of 300 r / min to obtain a pre-emulsion. 2. Seed emulsion preparation: Add 60 parts of deionized water and 1 part of sodium dodecyl sulfate to the reaction vessel, heat to 75°C, add 15% of pre-emulsion and 0.3 parts of ammonium persulfate, keep the reaction at this temperature for 40 min to obtain the seed emulsion; 3. Copolymerization reaction: The remaining pre-emulsion and 0.5 parts of ammonium persulfate were slowly added dropwise to the reactor through a constant pressure dropping funnel. The dropping time was controlled at 3 hours, and the reaction temperature was maintained at 80°C during the dropping process. After the dropping was completed, the reaction was kept at the temperature for another 1.5 hours. 4. Post-processing: After the reaction is completed, the temperature is lowered to below 40℃, the pH value of the system is adjusted to 7.5 with ammonia water, and after filtration and discharge, a modified acrylate copolymer emulsion with intramolecularly embedded fluorine / siloxane alkyl chains is obtained.

[0022] The preparation method of this water-based transparent peelable coating: 5. Add the modified acrylate copolymer emulsion with intramolecularly embedded fluorine / siloxane alkyl chains prepared above into a stirred tank, and start stirring at a speed of 200 r / min; 6. While stirring, slowly add deionized water and continue stirring for 15 minutes to ensure the system is thoroughly mixed. 7. Slowly add the film-forming aid dropwise into the mixing vessel, and stir for 25 minutes after the addition is complete; 8. Add the preservative and defoamer in sequence, and continue stirring for 35 minutes; 9. After stirring, filter the system through a 250-mesh filter to obtain a water-based transparent peelable coating.

[0023] Example 2 A water-based transparent peelable coating, by weight, comprises the following components: 70 parts of modified acrylate copolymer emulsion with intramolecularly embedded fluorine / siloxane alkyl chains, 15 parts of deionized water, 1 part of film-forming aid (ethylene glycol ethyl ether acetate), 0.3 parts of preservative (isothiazolinone), and 0.2 parts of defoamer (organosilicon).

[0024] The preparation methods of the modified acrylate copolymer emulsion with intramolecularly embedded fluorine / siloxane alkyl chains and the preparation methods of the coatings are basically the same as those in Example 1, with only some parameters adjusted: the stirring temperature in the pre-emulsification stage is 45°C and the stirring time is 50 min; the seed emulsion preparation temperature is 78°C; the copolymerization reaction dropping time is 3.5 h and the heat preservation reaction time is 2 h.

[0025] Example 3 A water-based transparent peelable coating, by weight, comprises the following components: 50 parts of modified acrylate copolymer emulsion with intramolecularly embedded fluorine / siloxane alkyl chains, 30 parts of deionized water, 0.1 parts of preservative (isothiazolinone), and 0.1 parts of defoamer (organosilicon).

[0026] The preparation methods of the modified acrylate copolymer emulsion with intramolecularly embedded fluorine / siloxane alkyl chains and the preparation methods of the coating are basically the same as those in Example 1, except that the pre-emulsification stage does not contain film-forming aids, and the copolymerization reaction dropwise addition time is 2.5 h, and the heat preservation reaction time is 1 h.

[0027] Performance testing The performance of the water-based transparent peelable coatings prepared in Examples 1-3 was tested, and the test results are shown in the table below: Table 1

[0028] The test results show that the water-based transparent peelable coating prepared by this invention has a uniform transparent appearance, high light transmittance, excellent peeling performance, and good storage stability. All its performance characteristics are superior to the industry standard requirements.

[0029] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An aqueous transparent strippable coating, characterized in that, The coating takes modified acrylic ester copolymer emulsion with fluorine / siloxane base chain embedded in the molecule as core film forming material.

2. The aqueous transparent strippable coating according to claim 1, characterized in that, The preparation method of the modified acrylic ester copolymer emulsion with fluorine / siloxane base chain embedded in the molecule comprises the following steps: S11 pre-emulsification: 20-40 parts of acrylic ester monomer, 5-15 parts of fluorine-containing monomer, 3-10 parts of siloxane group-containing monomer, 2-5 parts of emulsifier, 20-40 parts of deionized water are added into a pre-emulsification kettle, and stirred at 30-50℃ and a stirring speed of 200-400r / min for 30-60min to obtain a pre-emulsified solution; S12 seed emulsion preparation: 50-80 parts of deionized water and 0.5-2 parts of emulsifier are added into a reaction kettle, heated to 70-80℃, 10-20% of the pre-emulsified solution and 0.1-0.5 parts of initiator are added, and reacted for 30-60min to obtain a seed emulsion; S13 copolymerization reaction: the remaining pre-emulsified solution and 0.2-0.8 parts of initiator are slowly added into the reaction kettle through a constant pressure dropping funnel, the dropping time is controlled for 2-4h, and the reaction temperature is maintained at 75-85℃ during the dropping process; after the dropping is completed, the reaction is continued for 1-2h; S14 post-treatment: after the reaction is completed, the temperature is reduced to below 40℃, the pH value of the system is adjusted to 7.0-8.0 by using ammonia water, and the modified acrylic ester copolymer emulsion with fluorine / siloxane base chain embedded in the molecule is obtained after filtration and discharging.

3. The aqueous transparent strippable coating according to claim 2, characterized in that, The acrylic ester monomer is at least one selected from methyl methacrylate, ethyl acrylate, butyl acrylate and butyl methacrylate; the fluorine-containing monomer is at least one selected from fluorine-containing acrylate and fluorine-containing methacrylate; and the siloxane group-containing monomer is at least one selected from γ-methacryloyloxypropyl trimethoxysilane and vinyl triethoxysilane.

4. The aqueous transparent strippable coating of claim 2, wherein, The emulsifier is a compound system of anionic emulsifier and nonionic emulsifier, wherein the anionic emulsifier is at least one selected from sodium dodecyl benzene sulfonate and sodium dodecyl sulfate, the nonionic emulsifier is at least one selected from fatty alcohol polyoxyethylene ether and nonylphenol polyoxyethylene ether, and the weight ratio of the anionic emulsifier to the nonionic emulsifier is 1:1-3.

5. The aqueous transparent strippable coating of claim 2, wherein, The initiator is at least one selected from ammonium persulfate and potassium persulfate.

6. The aqueous transparent strippable coating of claim 1, wherein, The preparation method comprises the following steps:

7. The aqueous transparent strippable coating according to claim 6, wherein The preparation method comprises the following steps:

8. A process for preparing an aqueous transparent strippable coating as claimed in claim 6, characterized in that S21. The modified acrylic ester copolymer emulsion with fluorine / siloxane base chain embedded in the molecule is added into a stirring kettle, and stirring is started with a stirring speed of 150-250r / min; S22. Deionized water is slowly added under stirring, and the system is uniformly mixed by continuing stirring for 10-20min; S23. The system is filtered and discharged to obtain a coating. S23. Slowly drop the film forming assistant into the stirring kettle, and stir for 20-30 minutes after the dropping is completed; S24. Add the preservative and defoaming agent in sequence, and continue to stir for 30-40 minutes; S25. After the stirring is completed, filter the system through a 200-300 mesh filter screen to obtain the water-based transparent strippable coating.

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