Bottom coating agent for PET copper plating film and preparation method of bottom coating agent

Abstract

The invention relates to the field of PET base film primer, in particular to a primer for a PET copper plating film and a preparation method of the primer. The primer for the PET copper plating film is prepared from the following raw materials in parts by mass: 10-15 parts of modified castor oil resin, 6-8 parts of a coupling agent, 1.5-2 parts of a curing agent, 0.1-0.2 part of a catalyst, 3-4 parts of an adhesion promoter and 22-26 parts of a solvent. According to the primer for the PET copper plating film, through scientific formula design and molecular structure optimization, excellent bonding performance, high surface drying speed and good construction convenience are achieved, and the requirements of high-end markets can be met.

Description

Technical Field

[0001] The present application relates to the field of primers for PET base films, and in particular to a primer for PET copper-plated films and a preparation method thereof. Background Art

[0002] With the advancement of science and technology and the development of society, PET film has been widely used in various fields due to its excellent physical and chemical properties. However, in some high-end applications, it is difficult to meet higher functional requirements by relying solely on PET film, so surface modification and coating treatment have become a common way to improve it. At present, the demand for metallization treatment of the surface of PET film is increasing, especially in industries such as electronic component packaging and conductive circuit board manufacturing. The functional properties of PET film can be significantly improved by copper plating and other methods. However, PET film itself is a non-polar material and lacks a good bonding interface with the metal coating, which directly affects the quality and service life of the final product.

[0003] In order to overcome this challenge, the industry generally adopts pretreatment methods to enhance the bonding strength between PET film and metal coating. Common methods include but are not limited to: (1) Chemical oxidation method, that is, using specific chemical reagents to cause oxidation reaction on the PET surface to generate functional groups with higher polarity, thereby promoting the subsequent plating process; although this method is low-cost and easy to achieve large-scale production, it is easy to cause damage to the substrate and affect the yield rate. (2) Corona discharge treatment, using the electric field generated by a high-voltage power supply to treat the PET surface, activate its surface, form a microporous structure, which is conducive to enhancing the bonding strength of the subsequent coating; although this method can effectively improve the surface properties of PET film, there is a problem of uneven treatment in actual operation, and long-term treatment may cause the material to age and become brittle. (3) Plasma treatment technology, using radio frequency or DC glow discharge to generate low-temperature plasma, acting on the PET surface, can also achieve the purpose of activating the surface; the advantage of this technology is that it will hardly damage the PET substrate, but the equipment investment is large and the maintenance cost is relatively high.

[0004] Although the above methods can improve the surface properties of PET films to a certain extent, they still have limitations to varying degrees, such as unstable surface quality after treatment, high process complexity, and high cost. These factors limit their widespread application in industrial production. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present application provides a primer for PET copper-plated film and a preparation method thereof. The primer for PET copper-plated film prepared in the present application has excellent bonding strength and surface drying speed. By introducing modified castor oil resin, coupling agent and adhesion promoter into the primer, it has multiple functional groups, can form a strong chemical bond with the PET base film substrate, improve the adhesion of the coating, and also have excellent adhesion with the metal copper-plated layer, thereby improving the bonding strength between the PET base film and the metal copper-plated layer. In addition, the primer is simple to prepare, has a long storage validity period, is easy to construct, and can meet the needs of the high-end market.

[0006] In the first aspect, the present application provides a primer for a PET copper-plated film, which adopts the following technical solution: A primer for a PET copper-plated film comprises the following raw materials by weight: 10-15 parts of modified castor oil resin, 6-8 parts of coupling agent, 1.5-2 parts of curing agent, 0.1-0.2 parts of catalyst, 3-4 parts of adhesion promoter and 22-26 parts of solvent.

[0007] By adopting the above technical scheme, the modified castor oil resin is the main film-forming substance of the primer. By introducing the organosilicon chain segment and the silane coupling agent siloxy group into the castor oil structure, its compatibility and adhesion with the PET base film are enhanced. The modified resin not only improves the flexibility and weather resistance of the coating, but also can form a dense protective film on the surface of the PET base film. It works synergistically with the coupling agent and the adhesion promoter to form a strong chemical bond with the PET base film substrate through a variety of functional groups, thereby significantly improving the adhesion of the coating. The coupling agent usually contains a silane group, which can act as a bridge between the PET base film and the metal copper plating layer, and enhance the bonding force between the two by forming a covalent bond. It can also improve the water resistance and corrosion resistance of the coating. It works together with the modified castor oil resin and the adhesion promoter to further enhance the chemical bonding between the coating and the substrate and improve the overall bonding strength. The curing agent participates in the cross-linking reaction of the primer, promotes the curing process of the resin, makes the coating dry quickly and forms a stable three-dimensional network structure, and improves the mechanical properties and durability of the coating. Together with the catalyst, it accelerates the curing reaction, shortens the surface drying time, and ensures that the coating reaches a high hardness and adhesion in a short time. The catalyst can significantly reduce the activation energy of the curing reaction and accelerate the reaction rate, thereby shortening the surface drying time and curing time of the coating and improving production efficiency. It works synergistically with the curing agent to ensure that the coating cures quickly in a short time without affecting other properties of the coating. Adhesion promoters can improve the wettability and permeability between the coating and the substrate, and enhance the initial adhesion and final bonding strength of the coating. It usually contains polar groups that can form a strong interaction with the active sites on the surface of the substrate. It works together with modified castor oil resin and coupling agents to improve the bonding strength between the coating and the PET base film and the metal copper plating layer through various mechanisms. The solvent is mainly used to adjust the viscosity of the primer to make it easy to apply, and at the same time help the components to be evenly dispersed to ensure the flatness and consistency of the coating. By diluting and dispersing the components, it ensures that the primer has good fluidity and permeability during the construction process, which helps to improve the uniformity and adhesion of the coating. In summary, the various components in the primer for PET copper-plated film jointly improve the bonding strength and surface drying speed of the coating through their unique functions and synergistic effects, ensuring the excellent adhesion and long-term stability of the coating between the PET base film and the metal copper-plated layer.

[0008] Preferably, the modified castor oil resin comprises the following raw materials, by weight: 40-45 parts of castor oil, 18-20 parts of dimethyldisiloxane, 30-35 parts of silane coupling agent, 40-45 parts of isophorone diisocyanate, 0.001-0.0013 parts of chloroplatinic acid catalyst, and 140-160 parts of ethyl acetate.

[0009] By adopting the above technical scheme, castor oil provides a basic polyol structure, contains a large number of hydroxyl groups, can participate in the cross-linking reaction, and increase the flexibility and adhesion of the resin. Dimethyldisiloxane introduces silicone segments to improve the heat resistance and hydrolysis resistance of the resin. Silane coupling agent: such as N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, etc., provides siloxy groups to enhance the chemical bonding ability of the resin with the PET base film and the metal copper plating layer. Isophorone diisocyanate: provides isocyanate groups, reacts with hydroxyl and amino groups to form a cross-linking network, and improves the mechanical strength and chemical resistance of the resin. Chloroplatinic acid catalyst: promotes the hydrosilylation reaction and accelerates the reaction rate. Ethyl acetate: as a solvent, adjusts the viscosity of the reaction system, and facilitates the operation and control of the reaction. Modified castor oil resin plays a key role in the primer for PET copper-plated film. Through its unique structure and functional groups, it significantly improves the comprehensive performance of the coating.

[0010] Preferably, the silane coupling agent is at least one of N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, N-β-(aminoethyl)-γ-aminopropyltriethoxysilane and N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane. Preferably, the preparation method of the modified castor oil resin comprises the following steps: S41. First, add dimethyldisiloxane, one-fifth of the silane coupling agent and chloroplatinic acid catalyst into a reaction kettle according to the mass fractions, react for 40-50 minutes, slowly raise the temperature to 55-60° C., and add the remaining silane coupling agent dropwise within 2 hours; S42, after the addition is completed, continue to add the mixture of castor oil and ethyl acetate, slowly raise the temperature to 75-80° C., and the addition time is 3-3.5 hours; S43, after the addition is completed, react for 1.5-2 hours according to the mass fraction, then add isophorone diisocyanate, maintain the temperature at 75-80°C and react for 2-3 hours, after the reaction is completed, seal and store the discharged material to obtain modified castor oil resin.

[0011] By adopting the above technical scheme, the siloxy group and isocyanate group in the prepared modified castor oil resin can form chemical bonds with the PET base film and the metal copper-plated layer, significantly improving the adhesion of the coating. Through the cross-linking reaction of isophorone diisocyanate, a three-dimensional network structure is formed to improve the mechanical strength and chemical resistance of the resin. The introduction of dimethyl disiloxane gives the resin better heat resistance and hydrolysis resistance, extending the service life of the primer. With the synergistic effect of coupling agents and adhesion promoters, the bonding force between the coating and the substrate is further enhanced, and the overall bonding strength and surface drying speed are improved. In summary, the modified castor oil resin plays a key role in the primer for PET copper-plated film, and through its unique structure and functional groups, the comprehensive performance of the coating is significantly improved.

[0012] Preferably, the coupling agent is at least one of an isocyanate-containing silane coupling agent, a vinyl silane coupling agent and an amino silane coupling agent.

[0013] Preferably, the isocyanate-containing silane coupling agent is one of 3-isocyanatepropyltriethoxysilane and isocyanatepropylmethyldimethoxysilane; the vinyl silane coupling agent is one of vinyltrimethoxysilane and vinyltriethoxysilane; the aminosilane coupling agent is one of 3-aminopropyltrimethoxysilane and 3-aminopropyltriethoxysilane.

[0014] Preferably, the coupling agent is composed of isocyanate propylmethyldimethoxysilane, vinyltrimethoxysilane and 3-aminopropyltriethoxysilane in a mass ratio of 4:3:4.

[0015] By adopting the above technical scheme, in the primer for PET copper-plated film, the coupling agent used is composed of isocyanate propyl methyl dimethoxy silane, vinyl trimethoxy silane and 3-aminopropyl triethoxy silane in a mass ratio of 4:3:4. These components each play an important role in the primer and significantly improve the bonding strength between the PET base film and the metal copper-plated layer through a synergistic effect. Isocyanate propyl methyl dimethoxy silane: This compound contains an isocyanate group (-NCO) and a siloxane group (Si-O). The isocyanate group can react with the hydroxyl group (-OH) on the surface of the PET base film to form a stable chemical bond, thereby enhancing the adhesion between the primer and the PET base film. At the same time, the siloxane group can be hydrolyzed at high temperature to generate silanol (Si-OH), which is further condensed to form a siloxane network (Si-O-Si), thereby improving the heat resistance and mechanical properties of the coating. Vinyl trimethoxy silane: This compound contains a vinyl group (-CH=CH2) and a siloxane group. Vinyl groups can participate in free radical polymerization reactions and form covalent bonds with polar groups on the surface of PET base films, increasing the crosslinking density and adhesion of the coating. Siloxane groups can also be hydrolyzed at high temperatures to form silanols, which are further condensed to form siloxane networks, improving the heat resistance and mechanical properties of the coating. 3-Aminopropyltriethoxysilane: This compound contains amino groups (-NH2) and siloxane groups. Amino groups can form hydrogen bonds or covalent bonds with carboxyl groups (-COOH) or other polar groups on the surface of PET base films, enhancing the adhesion of the primer to the PET base film. Siloxane groups can also be hydrolyzed at high temperatures to form silanols, which are further condensed to form siloxane networks, improving the heat resistance and mechanical properties of the coating. These three silane coupling agents form chemical bonds with different functional groups on the surface of PET base films through isocyanate groups, vinyl groups and amino groups, respectively, to achieve multi-point anchoring, significantly improving the adhesion of the primer to the PET base film. Vinyl and siloxane groups can participate in free radical polymerization and hydrolysis condensation reactions to form a three-dimensional cross-linked network, improving the mechanical properties and heat resistance of the coating. Through the synergistic effect of different functional groups, the primer not only exhibits excellent adhesion on the PET base film, but also forms a stable chemical bond with the metal copper plating layer, thereby improving the overall bonding strength and durability. In summary, these three silane coupling agents play a key role in the primer for PET copper-plated film through their unique functional groups and synergistic effects, significantly improving the adhesion, surface drying speed and bonding strength of the coating.

[0016] Preferably, the adhesion promoter is composed of polyester polyurethane acrylate and vinyl diethyl phosphate in a mass ratio of 1:1.

[0017] By adopting the above technical solutions, polyester polyurethane acrylate: This component mainly provides flexibility and durability, while enhancing the adhesion between the coating and the substrate. It can form a dense film on the surface of the PET base film, increasing the mechanical properties and chemical resistance of the coating. Polyurethane acrylate has multiple reactive functional groups, such as hydroxyl, carboxyl and amino groups, which can undergo cross-linking reactions with polar groups on the surface of the PET base film, thereby improving adhesion. Vinyl diethyl phosphate: This component mainly acts as a cross-linking agent, forming a stable chemical bond with the copper ions on the metal surface through its phosphate group, thereby enhancing the bonding between the metal copper plating layer and the primer. Vinyl diethyl phosphate also has good wettability and permeability, and can penetrate into the tiny pores of the PET base film and the metal copper plating layer, further improving the adhesion of the coating. The polyester polyurethane acrylate and vinyl diethyl phosphate work together to form a multi-point cross-linking network between the PET base film and the metal copper plating layer. The flexibility and durability provided by polyurethane acrylate, combined with the strong cross-linking ability of vinyl diethyl phosphate, enable the coating to maintain good mechanical properties while significantly enhancing its adhesion to the substrate and metal layer. The synergistic effect of the two components can also improve the surface drying speed of the primer. Polyurethane acrylate helps to form a fast-curing film, while vinyl diethyl phosphate accelerates the curing process through cross-linking reactions, so that the primer can reach a high degree of drying in a short time, which is convenient for subsequent processes. The chemical resistance of polyester polyurethane acrylate combined with the stable chemical bonds of vinyl diethyl phosphate improves the durability and corrosion resistance of the primer in harsh environments. In summary, polyester polyurethane acrylate and vinyl diethyl phosphate work synergistically in the primer for PET copper-plated film, not only improving the adhesion between the coating and the PET base film and the metal copper-plated layer, but also improving the surface drying speed and chemical resistance of the primer, thereby meeting the needs of the high-end market.

[0018] Preferably, the catalyst is dibutyltin diacetate; the solvent is butyl acetate; and the curing agent is one of triphenylmethane triisocyanate, toluene diisocyanate and diphenylmethane diisocyanate.

[0019] In the second aspect, the present application provides a method for preparing a primer for a PET copper-plated film, using the following technical solution: As a general technical concept, the present application also provides a method for preparing the above-mentioned primer for a PET copper-plated film, comprising the following steps: After uniformly mixing the components in the formula according to the mass fraction, pour them into a ball mill, fill with high-purity nitrogen for protection, grind for 2.5 hours, discharge the material, filter with a 400-mesh sieve, and store in a sealed manner to obtain a primer for PET copper-plated film.

[0020] In summary, the present application includes at least one of the following beneficial technical effects: 1. Excellent bonding strength: By introducing modified castor oil resin, coupling agent and adhesion promoter into the primer, these ingredients contain multiple functional groups, which can form a strong chemical bond between the PET base film substrate and the metal copper plating layer, thereby significantly improving the adhesion and overall bonding strength of the coating.

[0021] 2. Fast surface drying speed: The optimized formula makes the primer have a faster surface drying speed, which helps to improve production efficiency and reduce construction time.

[0022] 3. Chemical bond forming ability: The molecular structure is designed based on the bonding mechanism, and the silicone chain segments and silane coupling agent's siloxy groups are introduced into the modified castor oil structure, which further enhances the chemical bond forming ability between the primer and the PET base film substrate, and improves the durability and stability of the coating.

[0023] 4. Construction convenience: The primer is simple to prepare, easy to construct, and has a long shelf life, which can meet the application needs of the high-end market.

[0024] 5. Wide applicability: It is not only suitable for PET base film, but also can form excellent adhesion with the metal copper-plated layer, ensuring the bonding strength between the PET base film and the metal copper-plated layer, and is suitable for a variety of high-demand industrial application scenarios. DETAILED DESCRIPTION

[0025] The embodiments of the present application will be described in detail below in conjunction with the examples, but it will be appreciated by those skilled in the art that the following examples are only used to illustrate the present application and should not be considered as limiting the scope of the present application. In the examples, if specific conditions are not specified, they are carried out according to normal conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0026] In the following examples and preparation examples, 1 part means 100 g.

[0027] Preparation Example 1 Preparation of modified castor oil resin The modified castor oil resin comprises the following raw materials, calculated by weight: 40 parts of castor oil, 18 parts of dimethyldisiloxane, 30 parts of N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, 40 parts of isophorone diisocyanate, 0.001 parts of chloroplatinic acid catalyst, and 140 parts of ethyl acetate; The preparation method of modified castor oil resin comprises the following steps: S41. According to the mass fractions, dimethyldisiloxane, one-fifth of N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane and chloroplatinic acid catalyst were first added into a reaction kettle and reacted for 40 minutes, then the temperature was slowly raised to 55° C., and the remaining N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane was added dropwise within 2 hours; S42, after the addition is completed, continue to add the mixture of castor oil and ethyl acetate, slowly raise the temperature to 75° C., and the addition time is 3.5 hours; S43, after the addition is completed, react for 1.5 hours according to the mass fraction, then add isophorone diisocyanate, keep the temperature at 75°C and react for 3 hours, after the reaction is completed, seal and store the discharged material to obtain modified castor oil resin.

[0028] Preparation Example 2 Preparation of modified castor oil resin The modified castor oil resin comprises the following raw materials, calculated by weight: 45 parts of castor oil, 20 parts of dimethyldisiloxane, 35 parts of N-β-(aminoethyl)-γ-aminopropyltriethoxysilane, 45 parts of isophorone diisocyanate, 0.0013 parts of chloroplatinic acid catalyst, and 160 parts of ethyl acetate; The preparation method of modified castor oil resin comprises the following steps: S41. According to the mass fractions, dimethyldisiloxane, one-fifth of N-β-(aminoethyl)-γ-aminopropyltriethoxysilane and chloroplatinic acid catalyst were first added into a reaction kettle and reacted for 50 minutes, then the temperature was slowly raised to 60° C., and the remaining N-β-(aminoethyl)-γ-aminopropyltriethoxysilane was added dropwise within 2 hours; S42, after the addition is completed, continue to add the mixture of castor oil and ethyl acetate, slowly raise the temperature to 80° C., and the addition time is 3 hours; S43, after the addition is completed, react for 2 hours according to the mass fraction, then add isophorone diisocyanate, keep the temperature at 80°C and react for 2 hours, after the reaction is completed, seal and store the discharged material to obtain modified castor oil resin.

[0029] Preparation Example 3 Preparation of modified castor oil resin The modified castor oil resin comprises the following raw materials, calculated by weight: 43 parts of castor oil, 19 parts of dimethyldisiloxane, 33 parts of N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane, 42 parts of isophorone diisocyanate, 0.0012 parts of chloroplatinic acid catalyst, and 150 parts of ethyl acetate; The preparation method of modified castor oil resin comprises the following steps: S41. According to the mass fractions, dimethyldisiloxane, one-fifth of N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane and chloroplatinic acid catalyst were first added into a reaction kettle and reacted for 45 minutes, then the temperature was slowly raised to 57° C., and the remaining N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane was added dropwise within 2 hours; S42, after the addition is completed, continue to add the mixture of castor oil and ethyl acetate, slowly raise the temperature to 78° C., and the addition time is 3.2 hours; S43, after the addition is completed, react for 1.8 hours according to the mass fraction, then add isophorone diisocyanate, keep the temperature at 78°C and react for 2.3 hours, after the reaction is completed, seal and store the discharged material to obtain modified castor oil resin.

[0030] Preparation Comparative Example 1 The preparation of castor oil resin is the same as that of Preparation Example 3, except that 0 part of N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane is used.

[0031] Example 1 A primer for a PET copper-plated film comprises the following raw materials, measured by weight: 10 parts of modified castor oil resin, 6 parts of a coupling agent, 1.5 parts of toluene diisocyanate, 0.1 parts of dibutyltin diacetate, 3 parts of an adhesion promoter, and 22 parts of butyl acetate; the modified castor oil resin is prepared according to Preparation Example 1; the coupling agent is composed of isocyanate propylmethyldimethoxysilane, vinyltrimethoxysilane and 3-aminopropyltriethoxysilane in a weight ratio of 4:3:4, and the adhesion promoter is composed of polyester polyurethane acrylate and vinyl diethyl phosphate in a weight ratio of 1:1.

[0032] The preparation method of the primer for the PET copper-plated film comprises the following steps: After uniformly mixing the components in the formula according to the mass fraction, pour them into a ball mill, fill with high-purity nitrogen for protection, grind for 2.5 hours, discharge the material, filter with a 400-mesh sieve, and store in a sealed manner to obtain a primer for PET copper-plated film.

[0033] Example 2 A primer for a PET copper-plated film comprises the following raw materials, measured by weight: 15 parts of modified castor oil resin, 8 parts of a coupling agent, 2 parts of diphenylmethane diisocyanate, 0.2 parts of dibutyltin diacetate, 4 parts of an adhesion promoter, and 26 parts of butyl acetate; the modified castor oil resin is prepared according to Preparation Example 2; the coupling agent is composed of isocyanate propylmethyldimethoxysilane, vinyltrimethoxysilane and 3-aminopropyltriethoxysilane in a weight ratio of 4:3:4, and the adhesion promoter is composed of polyester polyurethane acrylate and vinyl diethyl phosphate in a weight ratio of 1:1.

[0034] The preparation method of the primer for the PET copper-plated film comprises the following steps: After uniformly mixing the components in the formula according to the mass fraction, pour them into a ball mill, fill with high-purity nitrogen for protection, grind for 2.5 hours, discharge the material, filter with a 400-mesh sieve, and store in a sealed manner to obtain a primer for PET copper-plated film.

[0035] Example 3 A primer for a PET copper-plated film comprises the following raw materials, measured by weight: 13 parts of modified castor oil resin, 7 parts of a coupling agent, 1.8 parts of triphenylmethane triisocyanate, 0.15 parts of dibutyltin diacetate, 3.4 parts of an adhesion promoter, and 24 parts of butyl acetate; the modified castor oil resin is prepared according to Preparation Example 3; the coupling agent is composed of isocyanate propylmethyldimethoxysilane, vinyltrimethoxysilane and 3-aminopropyltriethoxysilane in a weight ratio of 4:3:4, and the adhesion promoter is composed of polyester polyurethane acrylate and vinyl diethyl phosphate in a weight ratio of 1:1.

[0036] The preparation method of the primer for the PET copper-plated film comprises the following steps: After uniformly mixing the components in the formula according to the mass fraction, pour them into a ball mill, fill with high-purity nitrogen for protection, grind for 2.5 hours, discharge the material, filter with a 400-mesh sieve, and store in a sealed manner to obtain a primer for PET copper-plated film.

[0037] Comparative Example 1 The same as Example 3, except that an equal amount of the castor oil resin prepared in Comparative Preparation Example 1 is used instead of the modified castor oil resin.

[0038] Comparative Example 2 The same as Example 3, except that: the coupling agent is isocyanate propylmethyldimethoxysilane.

[0039] Comparative Example 3 The same as Example 3, except that: the coupling agent is vinyltrimethoxysilane.

[0040] Comparative Example 4 The same as Example 3, except that: the coupling agent is 3-aminopropyltriethoxysilane.

[0041] Comparative Example 5 The same as Example 3, except that: the adhesion promoter is polyester polyurethane acrylate.

[0042] Comparative Example 6 The same as Example 3, except that: the adhesion promoter is polyester polyurethane acrylate.

[0043] Performance testing The primers for PET copper-plated films prepared in the above-mentioned Examples 1 to 3 and Comparative Examples 1 to 6 were sampled and subjected to the following tests. The results are shown in Table 1.

[0044] Surface drying time: the test was conducted according to the test method of GB / T 13477.5-2002; specifically, the primer for the PET copper-plated film prepared in the above-mentioned Examples 1 to 3 and Comparative Examples 1 to 6 was sprayed onto the PET base film, and the surface drying time was tested; Adhesion grade: according to ASTM D3359-09 standard test method; according to the following two methods, the adhesion between the primer coating for PET copper-plated film and the PET base film and the adhesion between the metal copper-plated layer and the primer coating layer for PET copper-plated film are tested respectively; the primer for PET copper-plated film prepared by the above-mentioned Examples 1-3 and Comparative Examples 1-6 is sprayed on the PET base film to obtain a primer coating with a thickness of 10 microns, and after curing and standing for 2 days, the adhesion between the primer coating for PET copper-plated film and the PET base film is tested respectively, and marked as the adhesion between the primer coating and the PET base film; the method of vacuum sputtering pure copper is used on the corresponding PET base film on which the primer coating has been formed to obtain a 1 micron pure copper layer, and after standing for 1 day, the adhesion between the primer coating for PET copper-plated film and the metal copper-plated layer is tested respectively, and marked as the adhesion between the primer coating and the metal copper-plated layer.

[0045] Table 1 Performance test Analyzing the data in Table 1, we can see that: 1) The primer for PET copper-plated film prepared in Examples 1 to 3 has excellent bonding strength and surface drying speed. By introducing modified castor oil resin, coupling agent and adhesion promoter into the primer, it has multiple functional groups, can form a strong chemical bond with the PET base film substrate, improve the adhesion of the coating, and also have excellent adhesion with the metal copper-plated layer, thereby improving the bonding strength between the PET base film and the metal copper-plated layer.

[0046] 2) The performance comparison analysis of the primer for PET copper-plated film prepared in Example 3 and Comparative Example 1 shows that the siloxy group and isocyanate group in the prepared modified castor oil resin can form chemical bonds with the PET base film and the metal copper-plated layer, significantly improving the adhesion of the coating. Through the cross-linking reaction of isophorone diisocyanate, a three-dimensional network structure is formed to improve the mechanical strength and chemical resistance of the resin. The introduction of dimethyl disiloxane gives the resin better heat resistance and hydrolysis resistance, extending the service life of the primer. The modified castor oil resin plays a key role in the primer for PET copper-plated film, and through its unique structure and functional groups, it significantly improves the comprehensive performance of the coating.

[0047] 3) Performance comparison analysis of the primer for PET copper-plated film obtained by Example 3 and Comparative Examples 2-4 shows that the coupling agent is composed of isocyanate propylmethyl dimethoxy silane, vinyl trimethoxy silane and 3-aminopropyl triethoxy silane in a mass ratio of 4:3:4. These components play an important role in the primer, and significantly improve the bonding strength between the PET base film and the metal copper-plated layer through a synergistic effect. These three silane coupling agents form chemical bonds with different functional groups on the surface of the PET base film through isocyanate groups, vinyl groups and amino groups, respectively, to achieve multi-point anchoring, and significantly improve the adhesion of the primer to the PET base film. Vinyl and siloxane groups can participate in free radical polymerization and hydrolysis condensation reactions to form a three-dimensional cross-linked network, which improves the mechanical properties and heat resistance of the coating. Through the synergistic effect of different functional groups, the primer not only shows excellent adhesion on the PET base film, but also can form a stable chemical bond with the metal copper-plated layer, significantly improving the adhesion, surface drying speed and bonding strength of the coating.

[0048] 4) The performance comparison analysis of the primer for PET copper-plated film prepared in Example 3 and Comparative Examples 5-6 shows that the adhesion promoter is composed of polyester polyurethane acrylate and vinyl diethyl phosphate in a mass ratio of 1:1. The use of polyester polyurethane acrylate and vinyl diethyl phosphate together can form a multi-point cross-linked network between the PET base film and the metal copper-plated layer. The flexibility and durability provided by polyurethane acrylate, combined with the strong cross-linking ability of vinyl diethyl phosphate, enable the coating to maintain good mechanical properties while significantly enhancing the adhesion to the substrate and the metal layer. The synergistic effect of the two components can also improve the surface drying speed of the primer. Polyurethane acrylate helps to form a fast-curing film, while vinyl diethyl phosphate accelerates the curing process through a cross-linking reaction, so that the primer reaches a high degree of dryness in a short time, which is convenient for the subsequent process. The chemical resistance of polyester polyurethane acrylate combined with the stable chemical bond of vinyl diethyl phosphate not only improves the adhesion between the coating and the PET base film and the metal copper plating layer, but also improves the surface drying speed and chemical resistance of the primer, thus meeting the needs of the high-end market.

[0049] The above embodiments are only used to explain the technical solutions of the present application rather than to limit them. Although the above embodiments provide a specific description of the present application, relevant technical personnel should understand that the specific implementation methods of the present application can still be modified or replaced by equivalents, and any modifications and equivalent replacements that do not depart from the spirit and scope of the present application should be included in the protection scope of the present application.

Claims

1. A primer for PET copper-plated film, characterized in that: The preparation raw materials include the following by weight: 10-15 parts of modified castor oil resin, 6-8 parts of coupling agent, 1.5-2 parts of curing agent, 0.1-0.2 parts of catalyst, 3-4 parts of adhesion promoter and 22-26 parts of solvent.

2. A primer for PET copper-plated film according to claim 1, characterized in that: The modified castor oil resin comprises the following raw materials by weight: 40-45 parts of castor oil, 18-20 parts of dimethyldisiloxane, 30-35 parts of silane coupling agent, 40-45 parts of isophorone diisocyanate, 0.001-0.0013 parts of chloroplatinic acid catalyst, and 140-160 parts of ethyl acetate.

3. A primer for PET copper-plated film according to claim 2, characterized in that: The silane coupling agent is at least one of N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, N-β-(aminoethyl)-γ-aminopropyltriethoxysilane and N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane.

4. A primer for PET copper-plated film according to claim 2 or 3, characterized in that: The preparation method of the modified castor oil resin comprises the following steps: S41. First, add dimethyldisiloxane, one-fifth of the silane coupling agent and chloroplatinic acid catalyst into a reaction kettle according to the mass fractions, react for 40-50 minutes, slowly raise the temperature to 55-60° C., and add the remaining silane coupling agent dropwise within 2 hours; S42, after the addition is completed, continue to add the mixture of castor oil and ethyl acetate, slowly raise the temperature to 75-80° C., and the addition time is 3-3.5 hours; S43, after the addition is completed, react for 1.5-2 hours according to the mass fraction, then add isophorone diisocyanate, maintain the temperature at 75-80°C and react for 2-3 hours, after the reaction is completed, seal and store the discharged material to obtain modified castor oil resin.

5. A primer for PET copper-plated film according to claim 1, characterized in that: The coupling agent is at least one of an isocyanate-containing silane coupling agent, a vinyl silane coupling agent and an amino silane coupling agent.

6. A primer for PET copper-plated film according to claim 5, characterized in that: The isocyanate-containing silane coupling agent is one of 3-isocyanatepropyltriethoxysilane and isocyanatepropylmethyldimethoxysilane; the vinyl silane coupling agent is one of vinyltrimethoxysilane and vinyltriethoxysilane; the aminosilane coupling agent is one of 3-aminopropyltrimethoxysilane and 3-aminopropyltriethoxysilane.

7. A primer for PET copper-plated film according to claim 1, characterized in that: The coupling agent is composed of isocyanate propylmethyldimethoxysilane, vinyltrimethoxysilane and 3-aminopropyltriethoxysilane in a mass ratio of 4:3:

4.

8. A primer for PET copper-plated film according to claim 1, characterized in that: The adhesion promoter is composed of polyester polyurethane acrylate and vinyl diethyl phosphate in a mass ratio of 1:

1.

9. A primer for PET copper-plated film according to claim 1, characterized in that: The catalyst is dibutyltin diacetate; the solvent is butyl acetate; and the curing agent is one of triphenylmethane triisocyanate, toluene diisocyanate and diphenylmethane diisocyanate.

10. A method for preparing a primer for PET copper-plated film according to any one of claims 1 to 9, characterized in that: The following steps are involved: After uniformly mixing the components in the formula according to the mass fraction, pour them into a ball mill, fill with high-purity nitrogen for protection, grind for 2.5 hours, discharge the material, filter with a 400-mesh sieve, and store in a sealed manner to obtain a primer for PET copper-plated film.

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