Pre-coating film capable of being used for hot-pressing laminating process and preparation method of pre-coating film

Abstract

The invention discloses a PVC (polyvinyl chloride) pre-coating film which comprises a PVC film substrate layer, a primer layer and a finish paint layer from bottom to top, the primer layer is prepared from the following raw materials in parts by weight: 60-80 parts of bifunctional polyether polyester modified polyurethane acrylate A, 20-40 parts of acrylate reactive diluent, 0.5-5 parts of photoinitiator and 0-10 parts of pigment filler; the finish paint layer is prepared from the following raw materials in parts by weight: 10 to 25 parts of bifunctional polyether polyester modified polyurethane acrylate A, 40 to 70 parts of 4.5 functional polyurethane acrylate B, 5 to 15 parts of acrylate reactive diluent, 0.5 to 5 parts of photoinitiator and 0.5 to 20 parts of pigment filler. Through cooperation of formula design and the technology, the problems that an existing pre-coating film is poor in stability at the low temperature and cracks are solved.

Description

Technical Field

[0001] The present invention relates to the field of coatings, and in particular, to a pre-coated film that can be used in a hot pressing process and a preparation method thereof. Background Art

[0002] In recent years, the pre-coated film technology has been more and more widely used, such as in the fields of furniture, PVC floors, automotive interiors, etc. However, its application in hot pressing LVT floors (Luxury Vinyl Tile) is somewhat hindered, mainly in two aspects. In winter, the film material will become hard, the film material will bend and crack during the production winding process, and it will break when slightly impacted during transportation and unloading. When hot pressing to form LVT floors, the coatings around the large board, deep-pressed textures and the nearby coatings will crack.

[0003] If the on-line laminating PVC floor technology (CN114887859 A) is applied, simply relying on a thick anti-deformation primer will be difficult to construct (the coating needs to be heated to 80 °C) and increase costs (three layers of coatings, and the anti-deformation primer requires 30 g / m2). Using general excimer PVC floor coatings or ordinary coatings with good flexibility, there will be no cracking after hot pressing, but there will be wrinkles, shiny in the deep grooves, and the coating performance will drop sharply.

[0004] In view of the existing background of solving the problems of low-temperature impact resistance and cracking, it is necessary to develop a pre-coated film coating technology that can solve these problems. Summary of the Invention

[0005] The purpose of the present invention is to provide a pre-coated film that can be used in a hot pressing process and a preparation method thereof, which solves the problems of poor stability and cracking of the existing pre-coated film at low temperatures.

[0006] The present invention achieves the above purpose through the following technical solutions:

[0007] A PVC pre-coated film, from bottom to top, includes a PVC film substrate layer, a primer layer and a topcoat layer. Among them, the preparation raw materials of the primer layer in parts by weight include: 60-80 parts by weight of 2-functional polyether polyester modified polyurethane acrylate A, 20-40 parts by weight of acrylate active diluent, 0.5-5 parts by weight of photoinitiator, 0-10 parts by weight of pigment filler; the preparation raw materials of the topcoat layer in parts by weight include: 10-25 parts by weight of 2-functional polyether polyester modified polyurethane acrylate A, 40-70 parts by weight of 4.5-functional polyurethane acrylate B, 5-15 parts by weight of acrylate active diluent, 0.5-5 parts by weight of photoinitiator, 0.5-20 parts by weight of pigment filler.

[0008] The present invention does not particularly limit the source of the PVC film substrate layer. According to the preferred embodiment of the present invention, the PVC film substrate layer is purchased from Guangdong Jinbang New Materials Co., Ltd.

[0009] In the preparation raw materials of the primer layer by weight, the present invention does not particularly limit the weight portion of the bifunctional polyether polyester modified polyurethane acrylate A. For example, it can be 60 to 80 parts by weight of the bifunctional polyether polyester modified polyurethane acrylate A. Exemplarily, the mass percentage of the bifunctional polyether polyester modified polyurethane acrylate A is 60 parts by weight, 65 parts by weight, 70 parts by weight, 75 parts by weight, 80 parts by weight, and any value within the range formed by any two of these point values.

[0010] The present invention does not particularly limit the weight portion of the acrylate active diluent. For example, it can be 20 to 40 parts by weight of the acrylate active diluent. Exemplarily, the mass percentage of the acrylate active diluent is 20 parts by weight, 30 parts by weight, 40 parts by weight, and any value within the range formed by any two of these point values.

[0011] The present invention does not particularly limit the weight portion of the photoinitiator. For example, it can be 0.5 to 5 parts by weight of the photoinitiator. Exemplarily, the mass percentage of the photoinitiator is 0.5 parts by weight, 1 part by weight, 2 parts by weight, 3 parts by weight, 4 parts by weight, 5 parts by weight, and any value within the range formed by any two of these point values.

[0012] The present invention does not particularly limit the weight portion of the pigment filler. For example, it can be 0 to 10 parts by weight of the pigment filler. Exemplarily, the mass percentage of the pigment filler is 0 parts by weight, 2 parts by weight, 4 parts by weight, 6 parts by weight, 8 parts by weight, 10 parts by weight, and any value within the range formed by any two of these point values.

[0013] In the preparation raw materials of the topcoat layer by weight, the present invention does not particularly limit the weight portion of the bifunctional polyether polyester modified polyurethane acrylate A. For example, it can be 10 to 25 parts by weight of the bifunctional polyether polyester modified polyurethane acrylate A. Exemplarily, the mass percentage of the bifunctional polyether polyester modified polyurethane acrylate A is 10 parts by weight, 15 parts by weight, 20 parts by weight, 25 parts by weight, and any value within the range formed by any two of these point values.

[0014] The present invention does not particularly limit the weight parts of the 4.5-functional polyurethane acrylate B. For example, it can be 4.5-functional polyurethane acrylate B with a mass of 40 to 70 weight parts. Exemplarily, the mass percentage of the 4.5-functional polyurethane acrylate B is 40 weight parts, 45 weight parts, 50 weight parts, 55 weight parts, 60 weight parts, 65 weight parts, 70 weight parts, and any value within the range formed by any two of these point values.

[0015] The present invention does not particularly limit the weight parts of the acrylate active diluent. For example, it can be an acrylate active diluent with a mass of 5 to 15 weight parts. Exemplarily, the mass percentage of the acrylate active diluent is 5 weight parts, 10 weight parts, 15 weight parts, and any value within the range formed by any two of these point values.

[0016] The present invention does not particularly limit the weight parts of the photoinitiator. For example, it can be a photoinitiator with a mass of 0.5 to 5 weight parts. Exemplarily, the mass percentage of the photoinitiator is 0.5 weight parts, 1 weight parts, 2 weight parts, 3 weight parts, 4 weight parts, 5 weight parts, and any value within the range formed by any two of these point values.

[0017] The present invention does not particularly limit the weight parts of the pigment and filler. For example, it can be a pigment and filler with a mass of 0.5 to 20 weight parts. Exemplarily, the mass percentage of the pigment and filler is 0.5 weight parts, 5 weight parts, 10 weight parts, 15 weight parts, 18 weight parts, 20 weight parts, and any value within the range formed by any two of these point values.

[0018] According to a preferred embodiment of the present invention, the 2-functional polyether polyester modified polyurethane acrylate A is prepared by reacting the following components: IPDI, where IPDI is isophorone diisocyanate; PCL 1000, where PCL 1000 is a polycaprolactone polyol with a molecular weight of 1000; PCL 2000, where PCL 2000 is a polycaprolactone polyol with a molecular weight of 2000; CHDM, where CHDM is 1,4-cyclohexanedimethanol; HEA, where HEA is 2-hydroxyethyl acrylate with a content of 97%; inhibitor, where the inhibitor is BHT, MEHQ; BHT is dibutylhydroxytoluene, and MEHQ is p-methoxyphenol; catalyst, where the catalyst is DBTL, and DBTL is dibutyltin dilaurate.

[0019] According to a preferred embodiment of the present invention, the molar ratio of the IPDI, the PCL 1000, the PCL 2000, the CHDM, the HEA, the BHT, the MEHQ, and the DBTL is: 1:1.2:1:1:0.067:0.0136:0.0399:0.00158.

[0020] According to a preferred embodiment of the present invention, the amounts of the IPDI, the PCL 1000, the PCL 2000, the CHDM, the HEA, the BHT, the MEHQ, and the DBTL are as follows: 0.1 mol of IPDI, where the IPDI is isophorone diisocyanate; 0.12 mol of PCL 1000, where the PCL 1000 is a polycaprolactone polyol with a molecular weight of 1000; 0.1 mol of PCL 2000, where the PCL 2000 is a polycaprolactone polyol with a molecular weight of 2000; 0.1 mol of CHDM, where the CHDM is 1,4-cyclohexanedimethanol; 0.8 ml of HEA, where the HEA is 2-hydroxyethyl acrylate with a content of 97%; polymerization inhibitors, where the polymerization inhibitors are 0.3 g of BHT and 0.6 g of MEHQ; 0.1 g of catalyst.

[0021] According to a preferred embodiment of the present invention, the catalyst is DBTL; the BHT is dibutylhydroxytoluene, the MEHQ is p-methoxyphenol, and the DBTL is dibutyltin dilaurate.

[0022] In the solution of the present invention, the specific content of the PCL 1000 improves the reaction activity of the solution of the present invention. The specific content of the PCL 2000 enhances the chain segment flexibility, synergistically optimizing the coating elasticity and adhesion. The hydroxyl functional groups contained in the PCL 1000 and / or the PCL 2000 react with the IPDI to form a polyurethane prepolymer, forming a coating skeleton structure.

[0023] In the solution of the present invention, the specific content of the CHDM is used as a chain extender to regulate the molecular chain segment regularity during the reaction, enhancing the coating hardness and scratch resistance; its cyclic structure can reduce the thermal shrinkage stress.

[0024] In the solution of the present invention, the specific content of the HEA introduces acrylic double bonds and hydroxyl groups during the reaction, participates in the synthesis of the polyurethane prepolymer, and provides active sites for UV curing at the same time.

[0025] In the solution of the present invention, the specific content of the BHT / MEHQ inhibits the pre-polymerization initiated by free radicals during storage or reaction, ensuring the formulation stability.

[0026] In the solution of the present invention, the specific content of the DBTL accelerates the polycondensation reaction of isocyanate and hydroxyl group during the reaction, shortens the reaction time and reduces the risk of side reactions.

[0027] According to a preferred embodiment of the present invention, the reaction comprises the following steps:

[0028] S1. Mix the PCL 1000, PCL 2000, and CHDM, heat up, dehydrate under vacuum, and cool to obtain mixture 1;

[0029] S2. Mix the mixture 1 obtained in step S1 with IPDI, stir and heat up, and then add the DBTL to obtain mixture 2;

[0030] S3. Add HEA, BHT, and MEHQ to the mixture 2 obtained in step S2 to obtain the difunctional polyether-polyester modified polyurethane acrylate A.

[0031] According to a preferred embodiment of the present invention, in step S1, after mixing, heat up to 110 °C, dehydrate under vacuum for 40 minutes, and cool to 25 °C.

[0032] According to a preferred embodiment of the present invention, in step S2, the reaction temperature is 55 - 60 °C, and the reaction is carried out for 0.5 h.

[0033] According to a preferred embodiment of the present invention, in step S3, the reaction temperature is 65 - 70 °C, and the reaction is carried out for 0.5 h.

[0034] In the present invention, in step S2, the reaction temperature is 55 - 60 °C, for example, it can be 55 °C, 57 °C, 60 °C, and any value within the range formed by any two of these point values.

[0035] In the present invention, in step S3, the reaction temperature is 65 - 70 °C, for example, it can be 65 °C, 67 °C, 70 °C, and any value within the range formed by any two of these point values.

[0036] The present invention also provides a method for preparing the primer, which includes mixing the difunctional polyether-polyester modified polyurethane acrylate A with an acrylate active diluent, a photoinitiator, and a pigment filler.

[0037] In the solution of the present invention, the specific content of the monofunctional acrylate monomer, as an active diluent, reduces the system viscosity to improve the workability; it participates in the UV curing crosslinking through homopolymerization or copolymerization to adjust the balance of coating flexibility and hardness.

[0038] According to a preferred embodiment of the present invention, the photoinitiator is selected from at least one of MBP, 184, and TPO-L; the pigment filler is SiO2.

[0039] In the solution of the present invention, the photoinitiator with a specific content decomposes under UV light to generate free radicals, triggering the polymerization reaction of acrylic double bonds to achieve rapid curing.

[0040] In the solution of the present invention, the pigment and filler with a specific content provide color hiding power; excessive addition may reduce the flexibility and curing efficiency of the coating.

[0041] According to a preferred embodiment of the present invention, the 4.5-functional polyurethane acrylate B is prepared by reacting the following components in parts by weight: 100 parts by weight of HT100, 20-50 parts by weight of HEA, 20-50 parts by weight of PETA, 0.5 part by weight of BHT, 1.0 part by weight of MEHQ, and 0.2 part by weight of DBTL.

[0042] In the present invention, the 4.5-functional polyurethane acrylate B is named as such because the inventor calculated the average functionality to be 4.5 through the integral area of the double bond and the main chain characteristic peak in the nuclear magnetic resonance hydrogen spectrum (1H-NMR) of the polyurethane acrylate prepared by reaction.

[0043] According to a preferred embodiment of the present invention, the HT100 is an HDI trimer, which is an aliphatic polyisocyanate curing agent with a mass fraction of —NCO ≈ 22.0%; the HEA is hydroxyethyl acrylate with a content of 97%; the PETA is pentaerythritol triacrylate; the BHT is dibutylhydroxytoluene, the MEHQ is p-methoxyphenol; the DBTL is dibutyltin dilaurate.

[0044] In the solution of the present invention, the HT100 (HDI trimer) with a specific content, as the main source of isocyanate (NCO) groups, reacts with polyols or hydroxyl-containing monomers to form the polyurethane main chain, and at the same time provides crosslinking sites through the trimer structure to enhance the rigidity of the material; its 3 NCO groups can react with the hydroxyl groups in HEA and PETA to form urethane bonds, constituting the polymer network skeleton.

[0045] According to a preferred embodiment of the present invention, the PETA is pentaerythritol triacrylate, which is a polyfunctional acrylate monomer containing three acrylate groups and has high reactivity, and is used to increase the crosslinking density and hardness of the coating.

[0046] In the solution of the present invention, the PETA with a specific content reacts with the HDI trimer (HT100) in the formulation to construct the rigid skeleton of the highly functional polyurethane acrylate B, enhancing the heat resistance (Tg≥70°C) and mechanical strength of the coating.

[0047] In the solution of the present invention, the specific content of the HEA (hydroxyethyl acrylate) has both hydroxyl reaction activity and acrylate double bond function, participates in the synthesis of the polyurethane main chain, and provides active sites required for UV curing; the hydroxyl group reacts with the NCO group of HT100, and the acrylate double bond undergoes free radical polymerization in the presence of a photoinitiator, enhancing the crosslinking density of the final product.

[0048] In the solution of the present invention, the specific content of the BHT (dibutylhydroxytoluene) is used as an antioxidant inhibitor to inhibit free radical side reactions caused by oxygen or heat during storage or processing, ensuring the stability of the system; by capturing free radicals to terminate the chain reaction, preventing premature polymerization of the prepolymer or monomer.

[0049] In the solution of the present invention, the specific content of the MEHQ (p-methoxyphenol) preferentially combines with free radicals, inhibits the self-polymerization of acrylate monomers, and prolongs the pot life of the system; it acts synergistically with BHT to form a dual protection mechanism, which is particularly suitable for UV curing systems containing acrylate double bonds.

[0050] In the solution of the present invention, the specific content of the DBTL (dibutyltin dilaurate) catalyzes the addition reaction of isocyanate and hydroxyl group, accelerates the formation of the polyurethane main chain, shortens the reaction time; by reducing the reaction activation energy, it promotes the efficient bonding of the NCO group and the hydroxyl group, ensuring the uniformity of the reaction system.

[0051] According to a preferred embodiment of the present invention, the reaction comprises the following steps:

[0052] S1. Mix the PETA, MEHQ and BHT and stir, then add the material HT100 to obtain mixture 1;

[0053] S2. Mix the mixture 1 obtained in step S1 with DBTL to obtain mixture 2;

[0054] S3. Add HEA to the mixture 2 obtained in step S2 to obtain the 4.5-functional polyurethane acrylate B.

[0055] According to a preferred embodiment of the present invention, in step S2, the reaction temperature is 50 - 60 °C, for example, it can be 50 °C, 55 °C, 60 °C, and any value within the range formed by any two of these point values. The reaction time is 1.5 h.

[0056] According to a preferred embodiment of the present invention, in step S3, the reaction temperature is 65 - 70 °C, for example, it can be 65 °C, 68 °C, 70 °C, and any value within the range formed by any two of these point values. The reaction time is 1.5 - 2 h, for example, it can be 1.5 h, 1.8 h, 2 h, and any value within the range formed by any two of these point values. The inventors have found that under this preferred specific embodiment, the solution of the present invention has a higher reaction yield.

[0057] The present invention also provides a method for preparing a topcoat, which includes mixing a difunctional polyether polyester modified polyurethane acrylate A, a 4.5-functional polyurethane acrylate B, an acrylate active diluent, a photoinitiator, and a pigment filler.

[0058] The present invention also provides a method for preparing the primer, which includes mixing a difunctional polyether polyester modified polyurethane acrylate A, an acrylate active diluent, a photoinitiator, and a pigment filler.

[0059] According to a preferred embodiment of the present invention, the acrylate active diluent is at least one of a monofunctional active diluent TMCHA, a monofunctional active diluent IBOA, and a monofunctional active diluent CTFA.

[0060] According to a preferred embodiment of the present invention, the photoinitiator is selected from at least one of MBP, 184, and TPO-L.

[0061] According to a preferred embodiment of the present invention, the pigment filler is SiO2.

[0062] The present invention also provides a method for preparing the pre-coated film, which includes the following steps:

[0063] S1. Stir the raw materials for preparing the primer layer and the topcoat layer evenly with a dispersion kettle respectively to obtain finished paint;

[0064] S2. Then coat the primer layer evenly on the surface of the PVC film substrate layer with a roller coater, and irradiate to semi-cure the primer layer;

[0065] S3. Then coat the topcoat layer evenly on the surface of the primer layer with a roller coater, and irradiate to pre-cure the topcoat layer;

[0066] S4. Perform surface curing with an excimer lamp and radiation complete curing on the pre-cured topcoat layer respectively, and shape it to obtain the PVC pre-coated film.

[0067] According to a preferred embodiment of the present invention, when irradiating the semi-cured primer, the light source is selected from at least one of an LED lamp, a mercury lamp, and a gallium lamp; when irradiating the pre-cured topcoat, the light source is a combined light source of an LED lamp, an excimer lamp, and a mercury lamp; when performing excimer surface curing on the pre-cured topcoat layer, the light source is an excimer lamp; when performing radiation full curing on the pre-cured topcoat layer, the light source is a mercury lamp and a gallium lamp.

[0068] According to a preferred embodiment of the present invention, the running linear speed of the equipment is 5 - 30 m / min, the coating thickness of the primer layer is 5 - 15 g / m 2 , the construction temperature for coating the primer layer is 25 - 40 °C, the coating thickness of the topcoat layer is 5 - 15 g / m 2 , and the construction temperature for coating the topcoat layer is 25 - 40 °C.

[0069] According to a preferred embodiment of the present invention, the running linear speed of the equipment is 15 - 20 m / min, the coating thickness of the primer layer is 7 - 8 g / m 2 , the construction temperature for coating the primer layer is 35 - 40 °C, the coating thickness of the topcoat layer is 9 - 11 g / m 2 , and the construction temperature for coating the topcoat layer is 25 - 40 °C.

[0070] The present invention also provides an application of the pre-coated film in a hot pressing and laminating process.

[0071] The beneficial effects of the present invention are as follows:

[0072] The present invention innovatively synthesizes an AB dual-resin system, realizing the synergistic optimization of three key indicators: Tg (≥70 °C for the topcoat / ≥40 °C for the primer), high elongation at break (≥8% for the topcoat / ≥20% for the primer), and low viscosity, overcoming the industry problem that commercially available high-Tg resins are difficult to balance flexibility and processability. The high topcoat Tg (≥70 °C) endows excellent high-temperature deformation resistance, and the retention rate of the film hardness under high-temperature conditions is improved. The high elongation at break design (≥8% for the topcoat / ≥20% for the primer) increases the low-temperature (-20 °C) impact crack resistance by more than 3 times, completely solving the problem of winter cracking of traditional products. By optimizing the monomer content (monomer in the topcoat < 15%), defects such as bubbles and delamination in the hot pressing and laminating LVT process are avoided, the yield rate is increased, and the processing loss cost is reduced. Specific Embodiments

[0073] The following further describes the present application in detail. It is necessary to point out here that the following specific embodiments are only used to further illustrate the present application and should not be construed as limiting the protection scope of the present application. Those skilled in the art can make some non-essential improvements and adjustments to the present application based on the above application content.

[0074] I. Main Raw Materials:

[0075] HT100 (HDI trimer): Purchased from Wanhua Chemical Group Co., Ltd.

[0076] PETA (pentaerythritol triacrylate): Purchased from Sartomer (Guangzhou) Chemical Co., Ltd.

[0077] IPDI (isophorone diisocyanate): Molecular weight 222.29, purchased from Wanhua Chemical Group Co., Ltd.

[0078] PCL 1000 (polycaprolactone polyol): Molecular weight 1000, purchased from Guangzhou Haoyi Chemical Technology Co., Ltd.

[0079] PCL 2000 (polycaprolactone polyol): Molecular weight 2000, purchased from Hunan Juren Chemical New Materials Technology Co., Ltd.

[0080] CHDM (1,4 - cyclohexanedimethanol): Molecular weight 144.21, purchased from Green Link (Jining) Chemical Technology Co., Ltd.

[0081] HEA (hydroxyethyl acrylate, 97%): Molecular weight 116.11, purchased from Jinan Aochen Chemical Co., Ltd.

[0082] BHT (dibutylhydroxytoluene): Molecular weight 220.35, purchased from Hunan Jushuo Biotechnology Co., Ltd.

[0083] MEHQ (p - methoxyphenol), molecular weight 138.16, purchased from Hubei Dechao Chemical Co., Ltd.

[0084] DBTL (dibutyltin dilaurate): Molecular weight 631.56, purchased from Shandong Jinyuanyuan New Materials Co., Ltd.

[0085] Monofunctional active diluent TMCHA: Purchased from Changxing Chemical Industry (Guangdong) Co., Ltd.

[0086] Monofunctional active diluent IBOA: Purchased from Changxing Chemical Industry (Guangdong) Co., Ltd.

[0087] Monofunctional active diluent CTFA: Purchased from Changxing Chemical Industry (Guangdong) Co., Ltd.

[0088] Photoinitiator TPO - L: Purchased from Wuhan Xinyang Ruihe Chemical Technology Co., Ltd.

[0089] Photoinitiator 184: Purchased from Hubei Hongxin Ruiyu Fine Chemical Co., Ltd.

[0090] Photoinitiator MBP: Purchased from Hunan Juren Chemical New Materials Technology Co., Ltd.

[0091] SiO2: Molecular weight 60.08, purchased from Wuhan Jinqu New Materials Co., Ltd.

[0092] 2-functional polyether polyurethane acrylate (Huihe HU9807): purchased from Dongguan Huihe New Materials Co., Ltd.

[0093] 2-functional polyether polyurethane acrylate (Zicai ZC6487): purchased from Shenzhen Zicai Technology Co., Ltd.

[0094] 6-functional polyester acrylate (Dymax BDT-1006): purchased from Dymax Corporation.

[0095] 6-functional polyurethane acrylate (Huihe 8200): purchased from Dongguan Huihe New Materials Co., Ltd.

[0096] 2-functional polyether polyurethane acrylate (Kunlong HM320): purchased from Jiangxi Kunlong New Materials Co., Ltd.

[0097] LED lamp: purchased from Shenzhen Yijia Electronic Technology Co., Ltd.

[0098] Excimer lamp: purchased from Taian Zibo Optoelectronic Technology Co., Ltd.

[0099] Mercury lamp: purchased from Zhuozhou Xupurui Electric Light Source Manufacturing Co., Ltd.

[0100] Gallium lamp: purchased from Dongguan Fuda Optoelectronic Equipment Technology Co., Ltd.

[0101] PVC excimer pre-coated film (3° product): Model: LLB-3C, purchased from Ningbo Lailibao New Materials Co., Ltd.

[0102] PVC excimer pre-coated film (4° product): Model: LLB-4C, purchased from Ningbo Lailibao New Materials Co., Ltd.

[0103] II. Examples

[0104] 1. Primer preparation steps:

[0105] S1. Mix 0.12 mol of PCL 1000, 0.1 mol of PCL 2000, and 0.1 mol of CHDM, then heat up to 110 °C, dehydrate under vacuum for 40 minutes, and cool to 25 °C to obtain mixture 1.

[0106] S2. Mix the mixture 1 obtained in step S1 with 0.1 mol of IPDI, stir and heat up to 55 - 60 °C, react for 0.5 h, and then add 0.1 g of DBTL to obtain mixture 2.

[0107] S3. Add 0.8 ml of hydroxyethyl acrylate with 97% HEA content, 0.3 g of BHT, and 0.6 g of MEHQ to the mixture 2 obtained in step S2. React at a temperature of 65 - 70 °C for 0.5 h to obtain difunctional polyether polyester modified polyurethane acrylate A.

[0108] S4. Use the difunctional polyether polyester modified polyurethane acrylate A prepared in the previous steps. Mix difunctional polyether polyester modified polyurethane acrylate A, monofunctional active diluent TMCHA, MBP, 184, and TPO-L, and stir evenly in a dispersion kettle to obtain the finished primer.

[0109] 2. Preparation steps of the topcoat: First, prepare difunctional polyether polyester modified polyurethane acrylate A and 4.5-functional polyurethane acrylate B, and then mix difunctional polyether polyester modified polyurethane acrylate A, 4.5-functional polyurethane acrylate B, acrylate active diluent, photoinitiator, and pigment filler, and stir evenly in a dispersion kettle to obtain the finished topcoat.

[0110] 1) Preparation steps of difunctional polyether polyester modified polyurethane acrylate A include:

[0111] S1. Mix 0.12 mol of PCL 1000, 0.1 mol of PCL 2000, and 0.1 mol of CHDM, then heat up to 110 °C, dehydrate under vacuum for 40 minutes, and cool to 25 °C to obtain mixture 1.

[0112] S2. Mix the mixture 1 obtained in step S1 with 0.1 mol of IPDI, stir and heat up to a temperature of 55 - 60 °C, react for 0.5 h, and then add 0.1 g of DBTL to obtain mixture 2.

[0113] S3. Add 0.8 ml of hydroxyethyl acrylate with 97% HEA content, 0.3 g of BHT, and 0.6 g of MEHQ to the mixture 2 obtained in step S2. React at a temperature of 65 °C for 0.5 h to obtain difunctional polyether polyester modified polyurethane acrylate A.

[0114] 2) Preparation steps of 4.5-functional polyurethane acrylate B include:

[0115] S1. Mix 30 g of PETA, 1.0 g of MEHQ, and 0.5 g of BHT, then stir, add 100 g of HT100 to the materials, and let it heat up naturally to obtain mixture 1.

[0116] S2. Mix the mixture 1 obtained in step S1 with 0.2 g of DBTL, and control the reaction temperature at 55 °C to obtain mixture 2.

[0117] S3. Add 30 g of HEA to the mixture 2 obtained in the step S2, slightly heat up to 65 °C, and continue the reaction for 2 h to obtain the 4.5-functional polyurethane acrylate B.

[0118] 3) The steps for preparing the topcoat include:

[0119] S4. Use the 2-functional polyether polyester modified polyurethane acrylate A and 4.5-functional polyurethane acrylate B prepared in the previous steps, mix and stir evenly with the mono-functional active diluent TMCHA, MBP, 184TPO-L and silica in a dispersion kettle to obtain the finished primer.

[0120] 3. Test the Tg and elongation at break of the primer and topcoat

[0121] Due to the interference of external curing factors, the data of Tg and elongation at break of the topcoat after curing have slight fluctuations. The coatings for testing Tg and elongation at break are obtained by the following method: coat the paint on a high-gloss PET film, cover it with a high-gloss OPP release film, and cure the coating with a high-pressure mercury lamp in an oxygen-free environment.

[0122] Specific steps:

[0123] 1. Coating preparation: Uniformly coat the topcoat paint on the surface of the high-gloss PET film, control the wet film thickness (it is recommended to use a wire bar or a doctor blade, with a thickness tolerance of ±5 μm); cover the high-gloss OPP release film to avoid the interference of oxygen penetration during the curing process and ensure an oxygen-free environment; use a high-pressure mercury lamp for photocuring, and control the light intensity (such as 80 - 120 mW / cm 2 ) and the exposure time (adjust according to the resin photoinitiator system). Curing environment control: Keep the temperature at 25 ± 2 °C and the humidity at 50 ± 5% throughout the curing process to reduce the influence of temperature and humidity on the curing rate and internal stress of the coating; peel off the release film after curing and let it stand for 24 hours to eliminate the residual stress.

[0124] 2. Glass transition temperature (Tg) test

[0125] According to the ISO6721-11 standard, cut 5 - 10 mg of samples from the coating, avoiding contamination or mechanical damage; encapsulate them with an aluminum crucible to ensure good contact with the DSC instrument, heat from 15 °C to 250 °C at a rate of 10 °C / min; cool to 15 °C at the same rate; heat up to 250 °C again at a rate of 10 °C / min, and record the heat flow curve. Take the inflection point or midpoint of the second heating curve as the Tg value and compare it with the baseline calibration data.

[0126] 3. Elongation at break test (tensile test)

[0127] According to ISO 527 standard, the coated layer is cut into dumbbell-shaped specimens (gage section width 10 mm, length 50 mm). The gage length is marked using laser scribing or non-contact optical marking (line width ≤ 0.1 mm) to avoid stress concentration introduced by mechanical scribing. Using a universal material testing machine, the tensile rate is set at 5 mm / min (flexible coating) or 50 mm / min (rigid coating). When clamping the specimen, ensure that the coaxiality deviation ≤ 0.2 mm / m to avoid early yielding. Record the stress-strain curve, read the gage length at break, and calculate the elongation at break according to the formula: 100%*(L_break - L_0) / L_0, where L_0 is the initial gage length and L_break is the gage length after break.

[0128] Table 1 Formulation tables of each raw material component of the topcoat and primer, and Tg and elongation at break

[0129]

[0130]

[0131]

[0132] According to the above preparation methods of the primer and the topcoat, primers D1 - D6 and topcoats M1 - M6 are prepared according to the formulations shown in Table 1.

[0133] 4. Preparation of the pre-coated film:

[0134] S1. Stir the raw materials for preparing the primer layer and the topcoat layer evenly with a dispersion kettle respectively to obtain the finished paint;

[0135] S2. Then, on the surface of the PVC film substrate layer, use a roller coater with a running line speed of 10 m / min to coat the primer layer evenly. The coating thickness of the primer layer is 10 g / m 2 ., and the construction temperature for coating the primer layer is 35°C; then irradiate the semi-cured primer layer with an LED lamp;

[0136] S3. Then, use a roller coater to coat the topcoat layer evenly on the surface of the primer layer. The coating thickness of the topcoat layer is 10 g / m 2 ., and the construction temperature for coating the topcoat layer is 35°C; then irradiate the pre-cured topcoat layer with a combined light source of an LED lamp, an excimer lamp, and a mercury lamp;

[0137] S4. Perform excimer lamp surface curing and radiation complete curing on the pre-cured topcoat layer respectively. Among them, when performing excimer lamp surface curing on the pre-cured topcoat layer, the light source is an excimer lamp; when performing radiation complete curing on the pre-cured topcoat layer, the light sources are a mercury lamp and a gallium lamp; finally, shape it to obtain the PVC pre-coated film.

[0138] The primer (D1 - D6) and the topcoat (M1 - M6) are processed on the surface of the PVC film substrate layer through the above steps and distributed according to the types of the primer (D1 - D6) and the topcoat (M1 - M6) shown in Table 2, and then the PVC pre-coated film is prepared. And Examples 1 - 6 and Comparative Examples 1 - 9 are obtained.

[0139] Table 2 Types of primer and topcoat for each example and comparative example

[0140]

[0141]

[0142] III. Performance testing

[0143] 1. For the pre-coated film finished product, after freezing at -18°C for 24 h, fold it with the coating facing outwards at -18°C, and observe whether the pre-coated film finished product breaks or crumbles.

[0144] 2. Hot press laminate into an LVT floor at 130 - 150°C, 3 - 5 MPa for 1 hour. Observe the cracking problem of the entire board surface: whether there is cracking around the board surface; scribble with a water-based pen at the densely embossed area and then wipe it clean with a dry tissue, and observe whether there are fine cracks; observe whether there are abnormal conditions such as wrinkling and shiny deep embossing on the entire board surface.

[0145] 3. Coat the coatings of each example and comparative example directly on the LVT floor by the same process and cure them, and compare the physical properties with the hot-pressed board surface (chemical resistance refers to ASTM F925, scratch resistance refers to ISO 1518). The chemical resistance of the coating after hot pressing will show a downward trend, and the difference in chemical resistance between the two is rated by the iodine tincture 5 - minute test, 0 "no decrease", 1 "slight decrease", 2 "obvious decrease", 3 "severe decrease". The iodine tincture resistance performance test will be affected by the color pattern of the color film, and the results will have slight fluctuations.

[0146] 4. Set 100 hot press laminate samples in parallel for each example and comparative example.

[0147] (2) Test results:

[0148] Table 3 Test results of each example and comparative example

[0149]

[0150]

[0151] As can be seen from Table 3, it is obvious that from Examples 1 - 6, Comparative Examples 1 - 3, 7: it is necessary that the topcoat Tg ≥ 70°C. From Example 1 and Comparative Examples 2, 7, it is necessary to maintain the elongation at break of the topcoat ≥ 8%. From Example 2 and Comparative Examples 4 - 7, it is necessary that the primer maintains Tg ≥ 40°C and the elongation at break ≥ 20%. Since it is difficult for high-Tg resins on the market to balance high elongation at break and low viscosity, the two resins A and B synthesized in the present invention well balance the three performance indicators. Thus, the formulations of Examples 1 - 6 can be obtained, and their performance is far superior to the formulation design concept of Comparative Example 7 on the market (since the formulation with a topcoat monomer content ≥ 15% has a large number of problems in the hot pressing and laminating LVT process, this formulation design concept is not included in the comparative examples). Thus, the problems of poor low-temperature impact resistance and cracking in the prior art are well solved, the yield rate and the finished product quality are greatly improved, and the cost is effectively reduced.

[0152] The above-described embodiments merely represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention.

Claims

1. A PVC pre-coated film, characterized in that: The invention comprises, from bottom to top, a PVC film substrate layer, a primer layer and a topcoat layer, wherein the raw materials for preparing the primer layer include, by weight: 60 to 80 parts by weight of a difunctional polyether polyester modified polyurethane acrylate A, 20 to 40 parts by weight of an acrylate reactive diluent, 0.5 to 5 parts by weight of a photoinitiator, and 0 to 10 parts by weight of a pigment filler; The raw materials for preparing the topcoat layer include, by weight: 10 to 25 parts by weight of difunctional polyether polyester modified polyurethane acrylate A, 40 to 70 parts by weight of 4.5-functionality polyurethane acrylate B, 5 to 15 parts by weight of acrylate reactive diluent, 0.5 to 5 parts by weight of photoinitiator, and 0.5 to 20 parts by weight of pigments and fillers.

2. The pre-coating film according to claim 1, wherein The difunctional polyether polyester modified polyurethane acrylate A is prepared by reacting the following components: IPDI, PCL 1000, PCL 2000, CHDM, HEA, BHT, MEHQ, and DBTL, wherein the molar ratio of the IPDI, the PCL 1000, the PCL 2000, the CHDM, the HEA, the BHT, the MEHQ, and the DBTL is 1:1.2:1:1:0.067:0.0136:0.0399:0.00158.

3. The pre-coated film according to claim 2, wherein: The reaction comprises the following steps: S1, mixing the PCL 1000, PCL 2000 and CHDM, heating, vacuum dehydrating, and cooling to obtain a mixture 1; In S1, the mixture was heated to 110°C, vacuum-dehydrated for 40 minutes, and cooled to 25°C. S2, mixing the mixture 1 obtained in step S1 with IPDI, stirring and heating, and then adding the DBTL to obtain a mixture 2; in S2, the reaction temperature is 55-60° C., and the reaction is carried out for 0.5 h S3, adding HEA, BHT and MEHQ to the mixture 2 obtained in the step S2 to obtain the difunctional polyether polyester modified polyurethane acrylate A; in the step S3, the reaction temperature is 65-70° C., and the reaction is carried out for 0.5 h.

4. The pre-coating film according to claim 1, wherein The 4.5-functionality polyurethane acrylate B is prepared by reacting the following components in parts by weight: 100 parts by weight of HT100, 20-50 parts by weight of HEA, 20-50 parts by weight of PETA, 0.5 parts by weight of BHT, 1.0 parts by weight of MEHQ, and 0.2 parts by weight of DBTL.

5. The pre-coating film according to claim 4, wherein: The reaction comprises the following steps: S1, mixing the PETA, MEHQ and BHT, and adding material HT100 to obtain mixture 1; S2, mixing the mixture 1 obtained in step S1 with DBTL to obtain a mixture 2; in step S2, The reaction temperature is 50-60°C and the reaction time is 1.5h; S3, adding HEA to the mixture 2 obtained in the step S2 to obtain the 4.5-functionality polyurethane acrylate B; in the step S3, the reaction temperature is 65-70° C., and the reaction is carried out for 1.5-2 hours.

6. A method for preparing a pre-coating film according to any one of claims 1 to 5, wherein: The following steps are involved: S1, the raw materials for preparing the primer layer and the topcoat layer are stirred evenly with a dispersion kettle to obtain a finished paint product; S2, evenly coating the primer layer on the surface of the PVC film substrate layer with a roller coater, and irradiating the semi-cured primer layer; S3, evenly coating the topcoat layer on the surface of the primer layer with a roller coater, and irradiating the pre-cured topcoat layer; S4. The pre-cured topcoat layer is subjected to surface curing by an excimer lamp and complete radiation curing respectively, and the PVC pre-coating film is obtained after shaping.

7. The method according to claim 6, wherein: When radiating semi-cured primer, the light source is selected from at least one of LED lamp, mercury lamp and gallium lamp; when radiating pre-cured topcoat, the light source is a combination of LED lamp, excimer lamp and mercury lamp; when radiating excimer surface curing of the pre-cured topcoat layer, the light source is an excimer lamp; when radiating fully cured pre-cured topcoat layer, the light source is a mercury lamp and a gallium lamp.

8. The method according to claim 6, wherein: The equipment running speed is 5-30m / min, and the coating thickness of the primer layer is 5-15g / m 2 , the primer coating construction temperature is 25-40℃, the topcoat coating thickness is 5-15g / m 2 , The construction temperature of the topcoat layer is 25-40℃.

9. The method according to claim 6, wherein: The equipment runs at a line speed of 15-20m / min and the coating thickness of the primer layer is 7-8g / m 2 , the primer coating construction temperature is 35-40℃, the topcoat coating thickness is 9-11g / m 2 , The construction temperature of the topcoat layer is 25-40℃.

10. Use of the pre-coating film according to any one of claims 1 to 5, wherein: Application of the pre-coated film in a hot pressing bonding process.

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