A high adhesion uv coating composition for corona treated pet and a method for preparing the hardened coating thereof

Abstract

The application relates to a high-adhesion UV coating composition applied to corona PET and a preparation method of a hardened coating layer thereof, wherein the coating composition comprises the following components: 20-60% of an amino-modified polyurethane acrylic oligomer; 0.4-1.2% of a leveling agent; 0.5-1.2% of an antistatic agent; 1-4% of a photoinitiator; and 40-75% of a solvent. The application solves the problems of poor adhesion of the UV coating on the corona PET film and the generation of pinholes, shrinkage holes and precipitation after high temperature and high humidity after coating.

Description

Technical Field

[0001] This invention belongs to the field of coating materials technology, specifically relating to a high-adhesion UV coating composition for corona-treated PET film (polyethylene terephthalate film) and its preparation method. Background Technology

[0002] UV coatings, also known as ultraviolet-cured coatings, are a type of new coating product widely used in modern industry. They are applied to the substrate surface automatically by roller coating or spray coating, where ultraviolet light irradiates the substrate, causing the initiator to decompose and generate free radicals that initiate a resin reaction, resulting in instantaneous curing into a film. In actual production, UV coatings offer advantages such as fast curing speed and high production efficiency.

[0003] In recent years, various new flat panel display (FPD) technologies and products, primarily represented by liquid crystal displays (LCDs), have developed rapidly, and the flat panel display industry has become an important part of the information industry. PET film, due to its advantages such as chemical corrosion resistance, high transparency, and ease of molding and processing, is widely used in the production of optical films such as diffusion films, reflective films, and brightness enhancement films. In industrial production, the film needs strong adhesion to ensure that the functional coating adheres firmly to the substrate, preventing it from easily detaching or peeling off, thereby enhancing its mechanical strength and durability. However, the low surface free energy of PET film leads to poor adhesion. Therefore, before preparing optical films, the surface of the PET film needs to be modified, such as by corona treatment, primer treatment, photochemical treatment, and low-temperature plasma treatment, to generate a large number of polar groups such as hydroxyl, carbonyl, and ketone groups on the film surface, thereby improving the adhesion between the PET film and the coating.

[0004] CN201210408829.6 discloses an environmentally friendly water-based high-adhesion PET pre-coating composition, its preparation, and its uses. The coating composition comprises the following components in parts by weight: 60-75 parts of water-based resin, 0-15 parts of co-solvent, and 0-20 parts of deionized water, wherein the weight parts of the co-solvent and deionized water are both 0 parts. Preferably, when the water-based resin is water-based acrylic, water-based polyurethane, or a mixture of water-based acrylic and water-based polyurethane, the environmentally friendly water-based high-adhesion PET pre-coating composition further comprises 5-10 parts by weight of a curing agent.

[0005] CN201410022989.6 discloses a UV coating containing cyclic acrylate to improve the adhesion of PET film. The coating contains cyclic acrylate, main resin, diluent and photoinitiator, and may or may not contain additives.

[0006] CN201510600687.7 provides a water-based anti-glare UV coating comprising the following components in parts by weight: water-based polyurethane acrylate prepolymer: 30-90 parts; diluent monomer: 10-60 parts; anti-glare particles: 5-100 parts; water-based wetting and dispersing agent: 0.05-10 parts; water-based leveling agent: 0.05-5 parts; water: 1-20 parts; water-based photoinitiator: 0.5-10 parts; water-based isocyanate curing agent: 1-30 parts.

[0007] CN201510829791.3 discloses a PET plastic vacuum electroplating UV coating, comprising the following components by weight percentage: 10-25% polyurethane-modified acrylic oligomer, 10-20% polyester acrylate, 5-15% trimethylolpropane triacrylate, 1.5-4% α-hydroxycyclohexyl benzophenone, 1-8% 10% acrylic functional resin, 2-15% methyl ethyl ketone, 35-50% ethyl acetate, 5-20% butyl acetate, and 1-8% cyclohexanone.

[0008] CN201610717284.5 discloses a UV coating for hot stamping and re-inking on the surface of PE hoses and its preparation method. The UV coating uses polyurethane acrylate and polyester acrylate with suitable functional groups and molecular structures as the main resin, selects difunctional crosslinkable monomers as polymerizable dilutable monomers, and combines dispersants, leveling agents, pigments and photoinitiators with appropriate structures to prepare a UV coating for hot stamping and re-inking on the surface of PE hoses.

[0009] CN201711380873.X discloses a UV-curable coating and its application. The UV-curable coating comprises the following components: 10%–70% oxygen-functionalized acrylic oligomers; 10%–70% nitrogen-functionalized acrylic oligomers; 5%–60% reactive diluent; 0.5%–15% photoinitiator; and 0.01%–4% leveling agent; all percentages are by weight.

[0010] CN202010572005.7 discloses a UV coating formulation and its preparation method. The UV coating formulation includes a film-forming substance, a colorant, and additives. The film-forming substance is composed of a photocurable resin and a photoinitiator. The photocurable resin includes any, but not only, resin types selected from unsaturated polyester, acrylated polyacrylate, epoxy resin, epoxy acrylate, polyurethane acrylate, and hyperbranched polyester acrylate. The preparation method of the UV coating formulation includes the following steps: S1, adding the photoinitiator, additives, and other auxiliaries to a reaction flask containing the photocurable resin, heating and stirring to ensure thorough mixing.

[0011] However, the resins used in existing UV coating formulations are relatively weakly polar, making it difficult to achieve good adhesion on corona-treated PET with low surface free energy, severely impacting product quality and application range. Furthermore, because existing UV coating formulations lack antistatic agents, the film surface easily attracts dust and other impurities from the air during actual optical film production. On the other hand, high-speed friction between the film and metal rollers can lead to air discharge, causing electric shock or fire, seriously affecting product quality, production efficiency, and production safety. Therefore, developing a UV-curing composition that can be directly coated onto corona-treated substrates with high adhesion and good antistatic properties has become a pressing issue for the industry.

[0012] Currently known modification treatments for PET films primarily involve primer coating. This involves first applying a primer as an intermediate layer to the film surface, followed by static curing at a constant temperature and humidity before applying a UV coating. This method is cumbersome and complex, and the drying process of the primer layer is energy-intensive, significantly impacting production efficiency and increasing costs. Corona treatment utilizes high-frequency, high-voltage electricity to discharge onto the plastic surface, causing the chemical bonds of the film surface molecules to break, degrade, or recombine, increasing surface roughness. While corona treatment improves the surface energy of PET films, adhesion to pure UV coatings remains poor. Furthermore, the effectiveness of corona treatment is easily affected by film surface temperature, air humidity, corona intensity, and treatment time, leading to reduced uniformity of the film structure. Therefore, after coating curing, problems such as pinholes, craters, and precipitation under high temperature and humidity often occur, severely impacting product quality and application range. Summary of the Invention

[0013] To address the problems of poor adhesion of UV coatings on corona-treated PET films and the occurrence of pinholes, shrinkage cavities, and precipitation after high temperature and humidity, this invention provides a high-adhesion UV coating composition for use on corona-treated PET and a method for preparing its hardened coating.

[0014] The high-adhesion UV coating composition provided by this invention, when applied to the surface of a corona-treated PET film, forms a hardened coating with an adhesion rating of 0 and a hardness of 2H. Under a 2000x optical microscope, no pinholes or craters are observed. No precipitation occurs after high temperature and humidity (65°C, 95% humidity, 500 hours), the film surface structure remains normal, and it exhibits good antistatic properties (resistivity 10). 11.0 -10 11.5 Ω*cm).

[0015] This invention provides a UV coating composition for use in corona-treated PET, the coating composition comprising the following components: 20%-60% amino-modified polyurethane acrylic oligomer; 0.4-1.2% leveling agent; 0.5-1.2% antistatic agent; 1-4% photoinitiator; and 40-75% solvent; the percentages are by weight; wherein the amino-modified polyurethane acrylic oligomer comprises acrylic resin containing bifunctional groups (F=2) and acrylic resin containing polyfunctional groups (F>2), where F is an abbreviation for functional group, and the weight ratio of the acrylic resin containing F=2 to the acrylic resin containing F>2 is 1-10:10; the silicone leveling agent is selected from one or a combination of at least two of polydimethylsiloxane, polymethylalkylsiloxane, organically modified polysiloxane, or silicone-modified acrylate; and the antistatic agent is selected from one or a combination of at least two of alkyl sulfonates, sulfates, phosphate derivatives, higher fatty acid salts, carboxylates, and polymeric ionic antistatic agents.

[0016] The amino-modified polyurethane acrylic resin selected in this invention contains a large number of amino groups and rigid groups. The amino groups readily react with polar groups such as hydroxyl and ester bonds on the surface of the PET substrate to form hydrogen bonds. The rigid groups can reduce the volume shrinkage rate of the resin during photocuring, thereby improving the adhesion of the UV coating to the corona-treated PET surface. By controlling the viscosity of the coating and reducing its internal stress, it achieves both strong adhesion to the corona-treated PET surface and high hardness, further expanding its application range. Furthermore, by rationally adjusting the types and amounts of anionic antistatic agents and silicone leveling agents, the coating formed by curing this UV coating composition on corona-treated PET exhibits excellent antistatic effects and film morphology.

[0017] Furthermore, the amino-modified polyurethane acrylic oligomer is preferably a combination of acrylic resins containing bifunctional groups (F=2), acrylic resins containing tetrafunctional groups (F=4), acrylic resins containing hexafunctional groups (F=6), and acrylic resins containing ninefunctional groups (F=9).

[0018] Furthermore, the content of the amino-modified polyurethane acrylic oligomer is 25%, 30%, 35%, 40%, or 50%.

[0019] Furthermore, the leveling agent is an organosilicon leveling agent.

[0020] Furthermore, the leveling agent content is 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, or 1.1%.

[0021] Furthermore, the antistatic agent is an ionic antistatic agent.

[0022] Furthermore, the content of the antistatic agent is 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, or 1.1%.

[0023] Furthermore, the photoinitiator is selected from one or a combination of at least two of 1-hydroxycyclohexylphenyl ketone (184), 2-hydroxy-methylphenylpropane-1-one (1173), 2,4,6-trimethylbenzoyl diphenylphosphine oxide (TPO) or 2,4,6-trimethylbenzoyl diphenylphosphine oxide benzophenone (BP).

[0024] Furthermore, the photoinitiator is preferably one or a combination of two of 184 and TPO.

[0025] Furthermore, the content of the photoinitiator is 2%, 2.5%, or 3%.

[0026] Furthermore, the solvent is selected from one or a combination of at least two of acetone, ethyl acetate, butyl acetate, chloroform, N,N-dimethylacetamide, or cyclohexane.

[0027] Furthermore, the solvent is preferably ethyl acetate or butyl acetate.

[0028] Furthermore, the remainder is solvent.

[0029] The present invention also provides a method for preparing the UV coating composition, comprising the following steps:

[0030] (1) Mix the above raw material components according to their weight ratio and disperse at 300-800r / min for 10-40min.

[0031] (2) Seal and store the mixed UV coating composition and let it stand for later use.

[0032] The present invention also provides a method for coating a high-adhesion UV-curable coating on corona-treated PET and the preparation method thereof, wherein the coating comprises a UV coating composition and polymethyl methacrylate (PMMA) particles, and the amount of PMMA particles added is 0-5%.

[0033] PMMA particles can be selectively added to coatings to provide haze, depending on the actual application environment.

[0034] Furthermore, the amount of PMMA particles added to the coating is 0.5%, 1%, 1.5%, 2%, 3%, and 4%.

[0035] Furthermore, the hardened coating is formed by UV curing of the composition provided by the present invention on a corona-treated PET film.

[0036] Furthermore, the thickness of the corona-electrode PET is 20-300μm, or 50μm, 80μm, 100μm, 150μm, 200μm, or 250μm, and the dyne value is 35-60, or 40, 45, 50, or 55.

[0037] Furthermore, the thickness of the corona-electrode PET is preferably 50-250 μm, and the dyne value is preferably 45-55.

[0038] Furthermore, the UV energy during the photocuring process is 100-600 mJ / cm². 2 Or 150 mJ / cm 2 200mj / cm 2 250mj / cm 2 300mj / cm 2 350mj / cm 2 400mj / cm 2 450mj / cm 2 500mj / cm 2 550mj / cm 2 580mj / cm 2 .

[0039] Furthermore, the UV energy during the photocuring process is preferably 150-350 mJ / cm². 2 .

[0040] The present invention also provides a method for preparing the coating, comprising the following steps:

[0041] (1) Remove oil, dust and other impurities from the surface of the PET film to ensure the effectiveness of the corona oxidation treatment;

[0042] (2) The PET film is placed in a corona discharge device for corona oxidation treatment;

[0043] (3) Add or not add PMMA to the UV coating composition as needed. Apply the UV coating composition to the surface of the corona-treated PET substrate layer. After uniform coating by wire rod / anilox roller, dry in an oven. After the solvent has completely evaporated, cure by UV lamp to form a hardened coating.

[0044] Furthermore, the drying temperature is 70℃-105℃, or 80℃, 90℃, or 100℃.

[0045] The present invention also provides the application of the coating composition in improving the adhesion between the coating and the PET film.

[0046] Compared with existing technologies, the high-adhesion UV coating composition provided by this invention can be directly coated onto corona-treated PET. After UV curing, the coating exhibits excellent adhesion to the PET film and possesses good scratch resistance, high hardness, and antistatic properties. This method has a simple preparation process, excellent overall performance, and significantly reduces production costs, making it suitable for mass production. Attached Figure Description

[0047] Figure 1 A schematic diagram of the cross-sectional structure of a film formed by curing a UV coating composition provided by the present invention on a corona-treated PET substrate; illustration: 1-corona-treated PET; 2-cured coating; 3-PMMA particles; 4-polar groups in an amino-modified polyurethane acrylic resin.

[0048] Figure 2 This is a comparison chart of adhesion tests between Comparative Example 8 and Example 12;

[0049] Figure 3 These are images of the film surface morphology of Comparative Example 8 and Example 12 under an optical microscope;

[0050] The UV coating composition was applied to the surface of a corona-treated PET substrate. After curing, a 100-grid pattern was drawn on the coating surface using a knife. The adhesion between the coating and the substrate was then tested using adhesive tape. Microscopic images of the test areas in Comparative Example 8 and Example 12 are shown below. Figure 2 (a) and Figure 2 As shown in (b). The UV coating composition in Comparative Example 8 exhibited poor adhesion on the corona-treated PET surface, with severe peeling between the coating and the substrate. This was due to the low polarity of the polyurethane acrylic resin in the formulation and the low surface energy of the corona-treated PET film. In contrast, the amino-modified polyurethane acrylic resin in Example 12 retained a large number of polar groups and contained rigid structures such as fused rings and alicyclic rings, which could reduce the volume shrinkage rate during curing. Therefore, it still showed good adhesion on the corona-treated PET surface. After the UV coating compositions of Comparative Example 8 and Example 12 were coated and cured on corona-treated PET, a high-temperature and high-humidity (temperature 65°C, humidity 95%) reliability test was conducted. After 500 hours, the film structure was observed under a microscope as shown below. Figure 3 (a) and Figure 3 As shown in (b). Figure 3 The areas marked by the blue dashed lines represent PMMA particles, while the areas marked by the red dashed lines represent coating precipitation. Due to the poor compatibility between the resin and the additives, a large amount of precipitation occurred in Comparative Example 8(a). In Example 12(b), by rationally adjusting the types and proportions of resin, antistatic agent, and leveling agent, precipitation after high temperature and high humidity was effectively avoided, and a good film morphology structure was observed under a microscope. Detailed Implementation

[0051] To better illustrate the purpose, technical solution, and advantages of this invention, the invention will be further described below in conjunction with the accompanying drawings and specific embodiments. Unless otherwise specified, the experimental methods used in the embodiments of this invention are conventional methods; unless otherwise specified, the materials and reagents used in the embodiments of this invention are commercially available.

[0052] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0053] The present invention provides a method for coating a corona-treated PET with a pure UV-curable coating, and the performance of the coating is tested according to the following method:

[0054] Adhesion: Performed in accordance with the national standard GB / T 9286-1998 Cross-cut test for paint and varnish film.

[0055] The specific procedure is as follows: Use a cross-cut adhesion tester to draw 10*10 (100) 1mm*1mm squares on the coating surface, ensuring each line penetrates to the bottom layer of paint. Then, gently brush away any debris from the test area. Firmly adhere the test grid to 3M 600-grade adhesive tape or equivalent tape, and vigorously rub the tape with an eraser to increase the contact area and adhesion between the tape and the test area. Grasp one end of the tape firmly and quickly tear it off vertically (90°). Repeat the same experiment twice at the same location. Determine the coating adhesion level based on the degree of coating peeling within the squares.

[0056] The cut edges are completely smooth, and there is no peeling at the grid edges, so the adhesion level is 0; there are small pieces of peeling at the intersection of the cuts, and the actual damage within the grid area is ≤5%, so the adhesion level is 1; there is peeling at the edges or intersections of the cuts, and the area is between 5% and 15%, so the adhesion level is 2; there is partial or large-scale peeling along the cut edges, and the peeling area is between 15% and 35%, so the adhesion level is 3; there is large-scale peeling at the cut edges, and the area is 35% to 65% of the grid area, so the adhesion level is 4; there are large areas of paint peeling off at the edges and intersections of the grid lines, and the peeling area is greater than 65%, so the adhesion level is 5.

[0057] Hardness: Performed in accordance with Chapter 4 of standard GB / 6739T, using a coating hardness tester (manufactured by Tianjin Jingke Material Testing Machine Factory, model: portable pencil hardness tester QHQ-A) that is tested by scratching with a pencil.

[0058] Surface resistance: The surface resistance of the hardened coating samples was measured according to ASTM D257. After the samples were left to stand for 24 hours at 23°C and 23% relative humidity, they were placed between the two electrodes of a SIMCO ION ST-4 testing device and exposed to a potential of 100V for 60 seconds. The surface resistance was recorded immediately afterward.

[0059] Membrane morphology and structure: Observed using a KEYENCE VK-X1000 microscope at 2000x magnification.

[0060] Scratch resistance: After the UV coating composition was cured on corona-treated PET, the scratch resistance of the hardened coating under the surface of a steel wool friction head was tested using a Jinliang A20-339 abrasion tester from Taiwan, China (200g load, 3 cycles). Evaluation level: Excellent > Good > Poor.

[0061] Example 1:

[0062] This invention provides a UV coating composition and a high-adhesion curing coating on corona-treated PET. The components of the UV coating are shown in Table 1. All resins used in the formulation are amino-modified polyurethane acrylic resins, wherein the proportions of difunctional polyurethane resin (Sartoma), tetrafunctional polyurethane resin (Sartoma), hexafunctional polyurethane resin (Mitsubishi), and nonafunctional polyurethane resin (Mitsubishi) are 10%, 10%, 12%, and 8%, respectively. The photoinitiator is a combination of TPO initiator and 184 initiator, accounting for 0.4% and 1.7%, respectively. The silicone leveling agent is BYK-320, accounting for 0.8%, and the antistatic agent is FC-4400 ionic antistatic agent, accounting for 0.86%. Ethyl acetate is used as the solvent, accounting for 56.24%. The above components are added to a mixing tank, stirred and dispersed evenly, and filtered to obtain the UV coating composition. The above coating is uniformly applied to the surface of a corona-treated PET substrate (150 μm thick, dyne value 50) using a wire rod / anilox roller, and then dried in an 80°C oven. After the solvent has completely evaporated, it is cured by UV irradiation to form a hardened coating.

[0063] The performance test results of the hardened coating formed by curing the UV coating composition of the present invention on a corona-cured PET film are shown in Table 3.

[0064] Example 2:

[0065] The UV coating composition and high-adhesion hardened coating on corona-treated PET, as shown in Example 1, have the following components: The resins used in the formulation are all amino-modified polyurethane acrylic resins, with the proportions of difunctional polyurethane resin (Sartoma), tetrafunctional polyurethane resin (Sartoma), hexafunctional polyurethane resin (Mitsubishi), and nonafunctional polyurethane resin (Mitsubishi) being 15%, 8%, 9%, and 8%, respectively. The proportions of TPO photoinitiator, 184 photoinitiator, leveling agent, and antistatic agent are 0.4%, 1.7%, 0.8%, and 0.86%, respectively. Ethyl acetate is used as the solvent, accounting for 56.24%. After the above components are added to a mixing drum and stirred until evenly dispersed, they are coated onto the surface of a corona-treated PET substrate (150 μm thick, dyne value 50) using a wire rod / anilox roller. The substrate is then dried in an 80°C oven until the solvent is completely evaporated, followed by UV irradiation to cure and form a hardened coating.

[0066] The performance test results of the hardened coating formed by curing the UV coating composition of the present invention on a corona-cured PET film are shown in Table 3.

[0067] Example 3:

[0068] The UV coating composition and high-adhesion hardened coating on corona-treated PET, as shown in Example 1, have the following components: The resins used in the formulation are all amino-modified polyurethane acrylic resins, with the proportions of difunctional polyurethane resin (Sartoma), tetrafunctional polyurethane resin (Sartoma), hexafunctional polyurethane resin (Mitsubishi), and nonafunctional polyurethane resin (Mitsubishi) being 12%, 8%, 12%, and 8%, respectively. The proportions of TPO photoinitiator, 184 photoinitiator, leveling agent, and antistatic agent are 0.4%, 1.7%, 0.8%, and 0.86%, respectively. Ethyl acetate is used as the solvent, accounting for 56.24%. After the above components are added to a mixing drum and stirred until evenly dispersed, they are coated onto the surface of a corona-treated PET substrate (150 μm thick, dyne value 50) using a wire rod / anilox roller. The substrate is then dried in an 80°C oven until the solvent is completely evaporated, followed by UV irradiation to cure and form a hardened coating.

[0069] The performance test results of the hardened coating formed by curing the UV coating composition of the present invention on a corona-cured PET film are shown in Table 3.

[0070] Example 4:

[0071] The UV coating composition and high-adhesion hardened coating on corona-treated PET, as shown in Example 1, have the following components: The resins used in the formulation are all amino-modified polyurethane acrylic resins, with the proportions of difunctional polyurethane resin (Sartoma), tetrafunctional polyurethane resin (Sartoma), hexafunctional polyurethane resin (Mitsubishi), and nonafunctional polyurethane resin (Mitsubishi) being 12%, 10%, 10%, and 8%, respectively. The proportions of TPO photoinitiator, 184 photoinitiator, leveling agent, and antistatic agent are 0.4%, 1.7%, 0.8%, and 0.86%, respectively. Ethyl acetate is used as the solvent, accounting for 56.24%. After the above components are added to a mixing drum and stirred until evenly dispersed, they are coated onto the surface of a corona-treated PET substrate (150 μm thick, dyne value 50) using a wire rod / anilox roller. The substrate is then dried in an 80°C oven until the solvent is completely evaporated, and then cured by UV irradiation to form a hardened coating.

[0072] The performance test results of the hardened coating formed by curing the UV coating composition of the present invention on a corona-cured PET film are shown in Table 3.

[0073] Example 5:

[0074] The UV coating composition and high-adhesion hardened coating on corona-treated PET, as shown in Example 1, have the following components: The resins used in the formulation are all amino-modified polyurethane acrylic resins, with the proportions of difunctional polyurethane resin (Sartoma), tetrafunctional polyurethane resin (Sartoma), hexafunctional polyurethane resin (Mitsubishi), and nonafunctional polyurethane resin (Mitsubishi) being 10%, 10%, 14%, and 6%, respectively. The proportions of TPO photoinitiator, 184 photoinitiator, leveling agent, and antistatic agent are 0.4%, 1.7%, 0.8%, and 0.86%, respectively. Ethyl acetate is used as the solvent, accounting for 56.24%. After the above components are added to a mixing drum and stirred until evenly dispersed, they are coated onto the surface of a corona-treated PET substrate (150 μm thick, dyne value 50) using a wire rod / anilox roller. The substrate is then dried in an 80°C oven until the solvent is completely evaporated, and then cured by UV irradiation to form a hardened coating.

[0075] The performance test results of the hardened coating formed by curing the UV coating composition of the present invention on a corona-cured PET film are shown in Table 3.

[0076] Example 6:

[0077] The UV coating composition and high-adhesion hardened coating on corona-treated PET, as shown in Example 1, have the following components: The resins used in the formulation are all amino-modified polyurethane acrylic resins, with the proportions of difunctional polyurethane resin (Sartoma), tetrafunctional polyurethane resin (Sartoma), hexafunctional polyurethane resin (Mitsubishi), and nonafunctional polyurethane resin (Mitsubishi) being 10%, 10%, 12%, and 8%, respectively. The proportions of TPO photoinitiator, 184 photoinitiator, leveling agent, and antistatic agent are 0.8%, 2.5%, 0.8%, and 0.86%, respectively. Ethyl acetate is used as the solvent, accounting for 55.04%. After the above components are added to a mixing drum and stirred until evenly dispersed, they are coated onto the surface of a corona-treated PET substrate (150 μm thick, dyne value 50) using a wire rod / anilox roller. The substrate is then dried in an 80°C oven until the solvent is completely evaporated, followed by UV irradiation to cure and form a hardened coating.

[0078] The performance test results of the hardened coating formed by curing the UV coating composition of the present invention on a corona-cured PET film are shown in Table 3.

[0079] Example 7:

[0080] The UV coating composition and high-adhesion hardened coating on corona-treated PET, as shown in Example 1, have the following components: The resins used in the formulation are all amino-modified polyurethane acrylic resins, with the proportions of difunctional polyurethane resin (Sartoma), tetrafunctional polyurethane resin (Sartoma), hexafunctional polyurethane resin (Mitsubishi), and nonafunctional polyurethane resin (Mitsubishi) being 10%, 10%, 12%, and 8%, respectively. The proportions of TPO photoinitiator, 184 photoinitiator, leveling agent, and antistatic agent are 0.3%, 1.2%, 0.8%, and 0.86%, respectively. Ethyl acetate is used as the solvent, accounting for 55.64%. After the above components are added to a mixing drum and stirred until evenly dispersed, they are coated onto the surface of a corona-treated PET substrate (150 μm thick, dyne value 50) using a wire rod / anilox roller. The substrate is then dried in an 80°C oven until the solvent is completely evaporated, followed by UV irradiation to cure and form a hardened coating.

[0081] The performance test results of the hardened coating formed by curing the UV coating composition of the present invention on a corona-cured PET film are shown in Table 3.

[0082] Example 8:

[0083] The UV coating composition and high-adhesion hardened coating on corona-treated PET, as shown in Example 1, have the following components: The resins used in the formulation are all amino-modified polyurethane acrylic resins, with the proportions of difunctional polyurethane resin (Sartoma), tetrafunctional polyurethane resin (Sartoma), hexafunctional polyurethane resin (Mitsubishi), and nonafunctional polyurethane resin (Mitsubishi) being 10%, 10%, 12%, and 8%, respectively. The proportions of TPO photoinitiator, 184 photoinitiator, leveling agent, and antistatic agent are 0.4%, 1.7%, 0.4%, and 0.86%, respectively. Ethyl acetate is used as the solvent, accounting for 56.64%. After the above components are added to a mixing drum and stirred until evenly dispersed, they are coated onto the surface of a corona-treated PET substrate (150 μm thick, dyne value 50) using a wire rod / anilox roller. The substrate is then dried in an 80°C oven until the solvent is completely evaporated, and then cured by UV irradiation to form a hardened coating.

[0084] The performance test results of the hardened coating formed by curing the UV coating composition of the present invention on a corona-cured PET film are shown in Table 3.

[0085] Example 9:

[0086] The UV coating composition and high-adhesion curing coating on corona-treated PET, as shown in Example 1, have the following components: The resins used in the formulation are all amino-modified polyurethane acrylic resins, with the proportions of difunctional polyurethane resin (Sartoma), tetrafunctional polyurethane resin (Sartoma), hexafunctional polyurethane resin (Mitsubishi), and nonafunctional polyurethane resin (Mitsubishi) being 10%, 10%, 12%, and 8%, respectively. The proportions of TPO photoinitiator, 184 photoinitiator, leveling agent, and antistatic agent are 0.4%, 1.7%, 1.2%, and 0.86%, respectively. Ethyl acetate is used as the solvent, accounting for 55.84%. After the above components are added to a mixing drum and stirred until evenly dispersed, they are coated onto the surface of a corona-treated PET substrate (150 μm thick, dyne value 50) using a wire rod / anilox roller. The substrate is then dried in an 80°C oven until the solvent is completely evaporated, followed by UV irradiation to cure and form a hardened coating.

[0087] The performance test results of the hardened coating formed by curing the UV coating composition of the present invention on a corona-cured PET film are shown in Table 3.

[0088] Example 10:

[0089] The UV coating composition and high-adhesion hardened coating on corona-treated PET, as shown in Example 1, have the following components: The resins used in the formulation are all amino-modified polyurethane acrylic resins, with the proportions of difunctional polyurethane resin (Sartoma), tetrafunctional polyurethane resin (Sartoma), hexafunctional polyurethane resin (Mitsubishi), and nonafunctional polyurethane resin (Mitsubishi) being 10%, 10%, 12%, and 8%, respectively. The proportions of TPO photoinitiator, 184 photoinitiator, leveling agent, and antistatic agent are 0.4%, 1.7%, 0.8%, and 0.46%, respectively. Ethyl acetate is used as the solvent, accounting for 56.64%. After the above components are added to a mixing drum and stirred until evenly dispersed, they are coated onto the surface of a corona-treated PET substrate (150 μm thick, dyne value 50) using a wire rod / anilox roller. The substrate is then dried in an 80°C oven until the solvent is completely evaporated, followed by UV irradiation to cure and form a hardened coating.

[0090] The performance test results of the hardened coating formed by curing the UV coating composition of the present invention on a corona-cured PET film are shown in Table 3.

[0091] Example 11:

[0092] The UV coating composition and high-adhesion hardened coating on corona-treated PET, as shown in Example 1, have the following components: The resins used in the formulation are all amino-modified polyurethane acrylic resins, with the proportions of difunctional polyurethane resin (Sartoma), tetrafunctional polyurethane resin (Sartoma), hexafunctional polyurethane resin (Mitsubishi), and nonafunctional polyurethane resin (Mitsubishi) being 10%, 10%, 12%, and 8%, respectively. The proportions of TPO photoinitiator, 184 photoinitiator, leveling agent, and antistatic agent are 0.4%, 1.7%, 0.8%, and 1.26%, respectively. Ethyl acetate is used as the solvent, accounting for 55.84%. After the above components are added to a mixing drum and stirred until evenly dispersed, they are coated onto the surface of a corona-treated PET substrate (150 μm thick, dyne value 50) using a wire rod / anilox roller. The substrate is then dried in an 80°C oven until the solvent is completely evaporated, followed by UV irradiation to cure and form a hardened coating.

[0093] The performance test results of the hardened coating formed by curing the UV coating composition of the present invention on a corona-cured PET film are shown in Table 3.

[0094] Example 12:

[0095] The UV coating composition and high-adhesion curing coating on corona-treated PET, as shown in Example 1, have the following components: The resins used in the formulation are all amino-modified polyurethane acrylic resins, wherein the proportions of difunctional polyurethane resin (Sartoma), tetrafunctional polyurethane resin (Sartoma), hexafunctional polyurethane resin (Mitsubishi), and nonafunctional polyurethane resin (Mitsubishi) are 10%, 10%, 12%, and 8%, respectively. The proportions of TPO photoinitiator, 184 photoinitiator, leveling agent, and antistatic agent are 0.4%, 1.7%, 0.8%, and 0.86%, respectively. PMMA is selected as a particle added to the coating to provide haze, with an addition ratio of 0.1%. Ethyl acetate is selected as the solvent, accounting for 56.14%. After the above components are added to the barrel and stirred and dispersed evenly, they are coated onto the surface of a corona-treated PET substrate (thickness of 150μm, dyne value of 50) by a wire rod / textured roller. Then, they are placed in an 80℃ oven to dry. After the solvent has completely evaporated, they are cured by UV irradiation to form a hardened coating.

[0096] The performance test results of the hardened coating formed by curing the UV coating composition of the present invention on a corona-cured PET film are shown in Table 3.

[0097] Example 13:

[0098] The UV coating composition and high-adhesion curing coating on corona-treated PET, as shown in Example 1, have the following components: The resins used in the formulation are all amino-modified polyurethane acrylic resins, wherein the proportions of difunctional polyurethane resin (Sartoma), tetrafunctional polyurethane resin (Sartoma), hexafunctional polyurethane resin (Mitsubishi), and nonafunctional polyurethane resin (Mitsubishi) are 10%, 10%, 12%, and 8%, respectively. The proportions of TPO photoinitiator, 184 photoinitiator, leveling agent, and antistatic agent are 0.4%, 1.7%, 0.8%, and 0.86%, respectively. PMMA is selected as a particle added to the coating to provide haze, with an addition ratio of 0.2%. Ethyl acetate is selected as the solvent, accounting for 56.14%. After the above components are added to the barrel and stirred and dispersed evenly, they are coated onto the surface of a corona-treated PET substrate (thickness of 150μm, dyne value of 50) by a wire rod / textured roller. Then, they are placed in an 80℃ oven to dry. After the solvent has completely evaporated, they are cured by UV irradiation to form a hardened coating.

[0099] The performance test results of the hardened coating formed by curing the UV coating composition of the present invention on a corona-cured PET film are shown in Table 3.

[0100] Comparative Example 1:

[0101] The UV coating composition and the high-adhesion hardened coating on corona-treated PET provided in Example 1 differ in that:

[0102] The resin used is a commercially available common polyurethane resin. Its difference from amino-modified polyurethane resin lies in the fewer polar groups it has, resulting in a larger volume shrinkage rate during curing. The proportions of difunctional, tetrafunctional, hexafunctional, and nonafunctional polyurethane resins are 10%, 10%, 12%, and 8%, respectively. The proportions of TPO photoinitiator, 184 photoinitiator, leveling agent, and antistatic agent are 0.4%, 1.7%, 0.8%, and 0.86%, respectively. Ethyl acetate is used as the solvent, accounting for 56.24%. After the above components are added to a mixing drum and stirred until evenly dispersed, they are coated onto the surface of a corona-treated PET substrate (150 μm thick, dyne value 50) using a wire rod / anilox roller. The substrate is then dried in an 80°C oven until the solvent is completely evaporated, followed by UV curing to form a hardened coating.

[0103] The performance test results of the hardened coating formed by curing the coating composition on a corona-treated PET film are shown in Table 3.

[0104] Comparative Example 2:

[0105] The UV coating composition and the high-adhesion hardened coating on corona-treated PET provided in Example 1 differ in that:

[0106] The resin used is a commercially available common polyurethane resin, with the proportions of difunctional, tetrafunctional, hexafunctional, and nonfunctional polyurethane resins being 15%, 8%, 9%, and 8%, respectively. The proportions of TPO photoinitiator, 184 photoinitiator, leveling agent, and antistatic agent are 0.4%, 1.7%, 0.8%, and 0.86%, respectively. Ethyl acetate is used as the solvent, accounting for 56.24%. After the above components are added to a mixing tank and stirred until evenly dispersed, they are coated onto the surface of a corona-treated PET substrate (150 μm thick, dyne value 50) using a wire rod / anilox roller. The substrate is then dried in an 80℃ oven until the solvent is completely evaporated, and then cured by UV irradiation to form a hardened coating.

[0107] The performance test results of the hardened coating formed by curing the coating composition on a corona-treated PET film are shown in Table 3.

[0108] Comparative Example 3:

[0109] The UV coating composition and the high-adhesion hardened coating on corona-treated PET provided in Example 1 differ in that:

[0110] The resin used is a commercially available common polyurethane resin, with the proportions of difunctional, tetrafunctional, hexafunctional, and nonfunctional polyurethane resins being 12%, 8%, 12%, and 8%, respectively. The proportions of TPO photoinitiator, 184 photoinitiator, leveling agent, and antistatic agent are 0.4%, 1.7%, 0.8%, and 0.86%, respectively. Ethyl acetate is used as the solvent, accounting for 56.24%. After the above components are added to a mixing tank and stirred until evenly dispersed, they are coated onto the surface of a corona-treated PET substrate (150 μm thick, dyne value 50) using a wire rod / anilox roller. The substrate is then dried in an 80℃ oven until the solvent is completely evaporated, followed by UV curing to form a hardened coating.

[0111] The performance test results of the hardened coating formed by curing the coating composition on a corona-treated PET film are shown in Table 3.

[0112] Comparative Example 4:

[0113] The UV coating composition and the high-adhesion hardened coating on corona-treated PET provided in Example 1 differ in that:

[0114] The resin used is a commercially available common polyurethane resin, with the proportions of difunctional, tetrafunctional, hexafunctional, and nonafunctional polyurethane resins being 12%, 10%, 10%, and 8%, respectively. The proportions of TPO photoinitiator, 184 photoinitiator, leveling agent, and antistatic agent are 0.4%, 1.7%, 0.8%, and 0.86%, respectively. Ethyl acetate is used as the solvent, accounting for 56.24%. After the above components are added to a mixing tank and stirred until evenly dispersed, they are coated onto the surface of a corona-treated PET substrate (150 μm thick, dyne value 50) using a wire rod / anilox roller. The substrate is then dried in an 80℃ oven until the solvent is completely evaporated, followed by UV curing to form a hardened coating.

[0115] The performance test results of the hardened coating formed by curing the coating composition on a corona-treated PET film are shown in Table 3.

[0116] Comparative Example 5:

[0117] The UV coating composition and the high-adhesion hardened coating on corona-treated PET provided in Example 1 differ in that:

[0118] The resin used is a commercially available common polyurethane resin, with the proportions of difunctional, tetrafunctional, hexafunctional, and nonafunctional polyurethane resins being 10%, 10%, 14%, and 6%, respectively. The proportions of TPO photoinitiator, 184 photoinitiator, leveling agent, and antistatic agent are 0.4%, 1.7%, 0.8%, and 0.86%, respectively. Ethyl acetate is used as the solvent, accounting for 56.24%. After the above components are added to a mixing tank and stirred until evenly dispersed, they are coated onto the surface of a corona-treated PET substrate (150 μm thick, dyne value 50) using a wire rod / anilox roller. The substrate is then dried in an 80℃ oven until the solvent is completely evaporated, and then cured by UV irradiation to form a hardened coating.

[0119] The performance test results of the hardened coating formed by curing the coating composition on a corona-treated PET film are shown in Table 3.

[0120] Comparative Example 6:

[0121] The UV coating composition and the high-adhesion hardened coating on corona-treated PET provided in Example 1 differ in that:

[0122] The resin used is a commercially available common polyurethane resin, with the proportions of difunctional, tetrafunctional, hexafunctional, and nonafunctional polyurethane resins being 10%, 10%, 12%, and 8%, respectively. The proportions of TPO photoinitiator, 184 photoinitiator, and antistatic agent are 0.4%, 1.7%, and 0.86%, respectively. No leveling agent is added. Ethyl acetate is used as the solvent, accounting for 57.04%. After the above components are added to a mixing tank and stirred to disperse evenly, they are coated onto the surface of a corona-treated PET substrate (150 μm thick, dyne value 50) using a wire rod / anilox roller. The substrate is then dried in an 80℃ oven until the solvent is completely evaporated, and then cured by UV irradiation to form a hardened coating.

[0123] The performance test results of the hardened coating formed by curing the coating composition on a corona-treated PET film are shown in Table 3.

[0124] Comparative Example 7:

[0125] The UV coating composition and the high-adhesion hardened coating on corona-treated PET provided in Example 1 differ in that:

[0126] The resin used is a commercially available common polyurethane resin, with the proportions of difunctional, tetrafunctional, hexafunctional, and nonafunctional polyurethane resins being 10%, 10%, 12%, and 8%, respectively. The proportions of TPO photoinitiator, 184 photoinitiator, and leveling agent are 0.4%, 1.7%, and 0.8%, respectively. No antistatic agent is added. Ethyl acetate is used as the solvent, accounting for 57.10%. After the above components are added to a mixing tank and stirred to disperse evenly, they are coated onto the surface of a corona-treated PET substrate (150 μm thick, dyne value 50) using a wire rod / anilox roller. The substrate is then dried in an 80℃ oven. After complete solvent evaporation, it is cured by UV irradiation to form a hardened coating.

[0127] The performance test results of the hardened coating formed by curing the coating composition on a corona-treated PET film are shown in Table 3.

[0128] Comparative Example 8: The UV coating composition and the high-adhesion hardened coating on corona-treated PET provided in Example 1 differ in that:

[0129] The resin used is a commercially available common polyurethane resin, with the proportions of difunctional, tetrafunctional, hexafunctional, and nonafunctional polyurethane resins being 10%, 10%, 12%, and 8%, respectively. The proportions of TPO photoinitiator, 184 photoinitiator, leveling agent, and antistatic agent are 0.4%, 1.7%, 0.8%, and 0.86%, respectively. PMMA is added as particles to the coating to provide haze, with an addition ratio of 0.1%. Ethyl acetate is used as the solvent, accounting for 56.14%. After the above components are added to a mixing tank and stirred evenly, they are coated onto the surface of a corona-treated PET substrate (150 μm thick, dyne value 50) using a wire rod / anilox roller. The substrate is then dried in an 80℃ oven until the solvent is completely evaporated, and then cured by UV irradiation to form a hardened coating.

[0130] The performance test results of the hardened coating formed by curing the coating composition on a corona-treated PET film are shown in Table 3.

[0131] Table 1 shows the components of the UV coating compositions provided in the examples.

[0132]

[0133]

[0134] The components of the UV coating compositions provided in Table 2 (comparative examples)

[0135]

[0136]

[0137] Table 3 shows the performance test results of coatings cured on corona-treated PET provided in the examples and comparative examples.

[0138]

[0139]

[0140] The test results of the above embodiments and comparative examples show that the present invention provides a high-adhesion UV coating composition for corona-treated PET by rationally combining the types and addition ratios of resin, photoinitiator, antistatic agent, leveling agent, and organic solvent. The high-adhesion UV coating composition provided by the present invention, after being coated on the surface of a corona-treated PET film, forms a coating with an adhesion grade of 0, a hardness of 2H, and no pinholes or craters under a 2000x optical microscope. No precipitation occurs after high temperature and high humidity (temperature 65℃, humidity 95%, 500h), the film surface structure is normal, and it exhibits good antistatic effects (resistivity 10). 11.0 -10 11.5 Ω*cm).

[0141] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. All equivalent changes and modifications made based on the content of the present invention are covered within the patent scope of the present invention.

Claims

1. A UV coating composition for use in corona-treated PET, said coating composition comprising 20%-60% amino-modified polyurethane acrylic oligomer; Leveling agent: 0.4-1.2%; Antistatic agent: 0.7-1.2%; Photoinitiator: 1-4%; balance is solvent; the percentages are by weight. The amino-modified polyurethane acrylic oligomer includes acrylic resins containing bifunctional groups (F=2) and acrylic resins containing polyfunctional groups (F>2), where F is an abbreviation for functional group. The weight ratio of the acrylic resin containing bifunctional groups (F=2) to the acrylic resin containing polyfunctional groups (F>2) is 1-10:

10. The leveling agent is selected from one or a combination of at least two of polydimethylsiloxane, polymethylalkylsiloxane, organic modified polysiloxane, or organosilicon modified acrylate. The antistatic agent is selected from one or a combination of at least two of alkyl sulfonates, sulfates, phosphate derivatives, higher fatty acid salts, carboxylates, and polymeric ionic antistatic agents; The amino-modified polyurethane acrylic oligomer is a combination of acrylic resins containing difunctional groups F=2, acrylic resins containing tetrafunctional groups F=4, acrylic resins containing hexafunctional groups F=6, and acrylic resins containing nonfunctional groups F=9. The solvent is selected from one or a combination of at least two of acetone, ethyl acetate, butyl acetate, chloroform, N,N-dimethylacetamide, or cyclohexane.

2. The UV coating composition according to claim 1, characterized in that The photoinitiator is selected from one or a combination of at least two of 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-methylphenylpropane-1-one, 2,4,6-trimethylbenzoyl diphenylphosphine oxide, or 2,4,6-trimethylbenzoyl diphenylphosphine oxide benzophenone.

3. A method for preparing the UV coating composition according to any one of claims 1 to 2, comprising the following steps: (1) Mix the above raw material components according to their weight ratio and disperse at 300-800 r / min for 10-40 min; (2) Seal and store the mixed UV coating composition and let it stand for later use.

4. A high-adhesion UV-curable coating applied to corona-treated PET, the UV-curable coating comprising a UV coating composition according to any one of claims 1 to 2 and polymethyl methacrylate (PMMA) particles, wherein the amount of PMMA particles added is 0.5-5%.

5. The UV-cured coating of claim 4, wherein, The amount of PMMA particles added in the coating is 1%, 1.5%, 2%, 3%, and 4%.

6. A method for preparing the hardened coating of claim 4 or 5, comprising the following steps: (1) Remove impurities from the surface of the PET film to ensure the effectiveness of the corona oxidation treatment; (2) The PET film is placed in a corona discharge device for corona oxidation treatment; (3) Add PMMA to the UV coating composition as needed, apply the UV coating composition to the surface of the corona-treated PET substrate layer, apply it evenly by wire rod / anilox roller and then dry it in an oven. After the solvent has completely evaporated, cure it by UV lamp to form a hardened coating.

7. The application of the UV coating composition according to any one of claims 1 to 2 in improving the adhesion and hardness between the coating and the PET film, wherein the coating is applied to a corona-treated PET film, cured by light, and the adhesion reaches grade 0 and the hardness is 2H.

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