High-performance thermal sublimation re-transfer printing film and preparation method thereof

Abstract

The invention relates to the technical field of thermal dye sublimation printing, in particular to a high-performance thermal dye sublimation re-transfer film and a preparation method. A release layer and a printing layer are arranged on one side of a base body, a back coating layer is arranged on the other side of the base body, and the back coating film is characterized in that a supporting layer is arranged between the release layer and the printing layer and comprises inorganic sol, water-based resin, whiteness improving pigment and solid filler; the inorganic sol is at least one of aluminum oxide sol and silicon dioxide sol, and the water-based resin is at least one of water-based polyurethane resin and water-based epoxy resin. The supporting layer can achieve dye blocking, the contact area with the printing head is increased, and the whiteness is effectively enhanced; resin in the printing layer can efficiently receive sublimation dye and has excellent heat resistance and adhesive force; and the back coating has good adhesive force and can meet the requirements of different printers.

Description

Technical Field

[0001] This invention relates to the field of thermal sublimation printing technology, and more specifically, to a high-performance thermal sublimation retransfer film and its preparation method. Background Technology

[0002] Dye-sublimation printing technology is widely used in fields such as graphic art reproduction and label printing due to its advantages of continuous color printing. However, it requires a transfer film as an intermediate medium to achieve printing on special substrates such as Xuan paper, silk cloth, and PP synthetic paper.

[0003] The typical structure of existing thermal sublimation retransfer films is "matrix-release layer-substrate layer", and its core function is to realize dye reception and transfer.

[0004] As the printing industry increases its requirements for image accuracy, color performance, and substrate compatibility, existing retransfer films are gradually revealing their shortcomings: (1) Dye penetration and uneven coating problem: The existing transfer film has no dye blocking structure and the solvent tension of the support layer (if present) is too high, which makes it impossible for the coating to be evenly coated on the release layer, further aggravating dye penetration, resulting in insufficient dye adsorption in the substrate layer and low color density (OD). (2) Poor printing uniformity: The existing coating is too rigid and it is difficult to fully adhere to the print head when in contact, resulting in uneven effective contact area and defects such as stripes and color difference in the printed image; (3) Insufficient whiteness: The existing film surface does not have a special whitening ingredient, and the whiteness is low, which affects the reproduction and visual effect of color images; (4) Limited performance of the printing layer: The existing printing layer has a main resin VC content of ≤45%, which is insufficient in heat resistance and dye absorption capacity, making it difficult to meet the requirements of high temperature and high precision printing. (5) Poor compatibility of back coating: The existing back coating solvent tension is too large, resulting in uneven coating. Furthermore, it has not been corona treated, resulting in poor coating adhesion and a fixed coefficient of friction. It cannot match the printing speed and pressure requirements of different printers, and is prone to problems such as paper jams and discontinuous printing.

[0005] The aforementioned problems have severely hampered the development and promotion of thermal sublimation printing technology. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a high-performance thermal sublimation retransfer film and its preparation method.

[0007] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: This invention provides a high-performance thermal sublimation retransfer film, comprising a substrate, a release layer and a substrate layer on one side of the substrate, a back coating layer on the other side, and a support layer between the release layer and the substrate layer. The support layer comprises inorganic sol, aqueous resin, whiteness-enhancing pigment and solid filler. The inorganic sol is at least one of alumina sol and silica sol, and the aqueous resin is at least one of aqueous polyurethane resin and aqueous epoxy resin.

[0008] Based on the above technical solution, the present invention can be further improved as follows.

[0009] Furthermore, the particle size of the solid filler is 1-3 μm.

[0010] Furthermore, the solid filler is at least one of polymethyl methacrylate microparticles and polystyrene microsphere microparticles.

[0011] Furthermore, it also includes a dispersant; in the support layer, the mass fractions of each component are: 30-50 parts of the aqueous resin, 5-10 parts of the solid filler, 1-3 parts of the whiteness-enhancing pigment, 5-10 parts of the inorganic sol, and 0.5-1 parts of the dispersant.

[0012] Furthermore, the substrate layer comprises a main resin, which is a chloroacetic acid resin with a high vinyl chloride content; The chloroacetic acid resin includes chloroacetic acid resin and / or chloroacetic acid-acrylic acid copolymer, wherein the mass percentage of vinyl chloride is greater than 86%.

[0013] Furthermore, the substrate layer also includes auxiliary resins, which include high Tg synthetic resins and polyvinyl butyral resins. The high-Tg synthetic resin has a Tg greater than or equal to 80°C, and the resin type is polyester resin and / or acrylic resin.

[0014] Furthermore, it also includes a crosslinking agent, a heat-resistant lubricant, and an adhesion promoter; the mass fractions of each component in the substrate layer are as follows: 60-80 parts of the main resin, 10-20 parts of the high Tg synthetic resin, 10-20 parts of the polyvinyl butyral resin, 1-5 parts of the crosslinking agent, 0.5-1 part of the heat-resistant lubricant, and 1-3 parts of the adhesion promoter.

[0015] Furthermore, the back coating comprises velvety flour powder and / or silica powder with a particle size of 5-10 μm.

[0016] This invention also provides a method for preparing the high-performance thermal sublimation retransfer film as described above, comprising the following steps: Release layer coating liquid, support layer coating liquid, substrate coating liquid and back coating liquid are prepared separately, wherein the support layer coating liquid contains the inorganic sol, the aqueous resin, the whiteness-enhancing pigment and the solid filler; The other side of the substrate is subjected to corona treatment, then the back coating liquid is applied, and the back coating is obtained after drying. Each layer is prepared on one side of the substrate by sequentially applying the release layer coating liquid, the support layer coating liquid, and the printing layer coating liquid through a coating-drying process.

[0017] Furthermore, after the corona treatment, the dyne value on the other side of the substrate is greater than 48.

[0018] Furthermore, the solvent of the support layer coating liquid is an isopropanol-water solution with a volume ratio of 1:1, or an ethanol-water solution with a volume ratio of 1:1, and the coating thickness is 0.7-1.3 μm.

[0019] Furthermore, the solvent in the back coating coating liquid is an isopropanol-water solution with a volume ratio of 1:1, or a propylene glycol methyl ether-water solution with a volume ratio of 1:1; the coating thickness is 0.7-1.3 μm.

[0020] Furthermore, the coating thickness of the release layer coating liquid is 0.2-0.8 μm, and the coating thickness of the substrate coating liquid is 1.5-2.5 μm.

[0021] The beneficial effects of this invention are as follows: (1) The high-performance thermal sublimation retransfer film of the present invention adds a support layer between the release layer and the substrate layer. The inorganic sol contained in the support layer can form a barrier layer to block the dye. The water-based resin can provide flexible support and increase the contact area with the print head. The whiteness-enhancing pigment can effectively enhance the whiteness. (2) The high-performance thermal sublimation retransfer film of the present invention has a resin in the substrate layer that can efficiently receive thermal sublimation dyes and has excellent heat resistance and adhesion. (3) The high-performance thermal sublimation retransfer film preparation method of the present invention, after corona treatment of the substrate to make its dyne value greater than 48mN / m, can improve the adhesion between the back coating and the substrate by 2-3 times and avoid the back coating from falling off during the printing process. (4) In the high-performance thermal sublimation retransfer film preparation method of the present invention, the selection of solvent for the support layer coating liquid can effectively reduce the coating tension, ensure that it is uniformly coated on the release layer, and effectively improve the printing uniformity. (5) The high-performance thermal sublimation retransfer film preparation method of the present invention ensures coating uniformity and adhesion by controlling the solvent of the back coating liquid and corona treatment of the substrate, and at the same time controls the friction coefficient by the textured surface design to adapt to the needs of different printers. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the layer structure of the high-performance thermal sublimation retransfer film of the present invention.

[0023] The attached diagram lists the components represented by each number as follows: 1. Substrate; 2. Release layer; 3. Support layer; 4. Printing substrate; 5. Back coating layer. Detailed Implementation

[0024] The principles and features of the present invention are described below. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0025] like Figure 1 As shown, the high-performance thermal sublimation retransfer film of the present invention includes a substrate 1, a release layer 2 and a substrate layer 4 on one side of the substrate 1, a back coating layer 5 on the other side, and a support layer 3 between the release layer 2 and the substrate layer 4. The support layer 3 comprises an inorganic sol, an aqueous resin, a whiteness-enhancing pigment, and a solid filler; wherein the inorganic sol is at least one of alumina sol and silica sol, and the aqueous resin is at least one of aqueous polyurethane resin and aqueous epoxy resin.

[0026] The high-performance thermal sublimation retransfer film of the present invention adds a support layer 4 between the release layer 2 and the substrate layer 4. The inorganic sol contained in the support layer 4 can form a barrier layer to block dye. The water-based resin can provide flexible support, increase the contact area with the print head, and the whiteness-enhancing pigment can effectively enhance the whiteness.

[0027] Preferably, during the preparation process, the solvent of the support layer coating liquid is an isopropanol-water solution with a volume ratio of 1:1, or an ethanol-water solution with a volume ratio of 1:1. The selection of the above solvent can effectively reduce the tension of the coating, ensure that it is uniformly coated on the release layer 2, and effectively improve the printing uniformity.

[0028] Specifically, an isopropanol-water solution or an ethanol-water solution with a volume ratio of 1:1 has a surface tension of about 30-35 mN / m, which matches the surface tension of the release layer 2 (about 38-42 mN / m after the release layer coating liquid is applied to one side of the substrate 1 after corona treatment). This avoids the coating pinholes caused by excessive tension in pure aqueous solutions (surface tension of about 72 mN / m), ensuring coating uniformity.

[0029] Preferably, the particle size of the solid filler is 1-3 μm.

[0030] Preferably, the solid filler is at least one of polymethyl methacrylate microparticles and polystyrene microspheres.

[0031] Preferably, the support layer 3 also includes a dispersant, and the mass percentages of each component are: 30-50 parts of aqueous resin, 5-10 parts of solid filler, 1-3 parts of whiteness-enhancing pigment, 5-10 parts of inorganic sol, and 0.5-1 parts of dispersant. When preparing the coating solution, the mass percentage of the mixed solvent used is 30-50 parts.

[0032] Preferably, the pigment used to enhance whiteness is ultramarine pigment or titanium dioxide pigment.

[0033] The printing layer 4 of this invention can efficiently receive sublimation dyes and possesses excellent heat resistance and adhesion. Its composition includes a main resin, which is a vinyl chloride (VC)-based resin with a high VC content; wherein the VC-based resin includes VC resin and / or VC-based acrylic copolymer, and the mass percentage of VC is greater than 86%.

[0034] Specifically, when the VC content of chloroacetic acid resin is >86%, the density of chlorine atoms in the molecular chain is higher, and the compatibility with thermal sublimation dyes is improved by more than 40%. At the same time, the glass transition temperature (Tg) of chloroacetic acid resin with this VC content can be increased to 65-75℃, and its heat resistance is significantly better than that of low VC resin (VC≤45%, Tg about 40-50℃).

[0035] Preferably, the mass percentage of vinyl chloride is 88%-90%.

[0036] Preferably, the substrate 4 also includes auxiliary resins, which include high Tg synthetic resins and polyvinyl butyral resins; wherein the high Tg synthetic resins have a Tg greater than or equal to 80°C, and the resin type is polyester resin and / or acrylic resin.

[0037] Preferably, the substrate layer 4 further comprises a crosslinking agent, a heat-resistant lubricant, and an adhesion promoter; the mass fractions of each component are: 60-80 parts of main resin, 10-20 parts of high Tg synthetic resin, 10-20 parts of polyvinyl butyral resin, 1-5 parts of crosslinking agent, 0.5-1 part of heat-resistant lubricant, and 1-3 parts of adhesion promoter.

[0038] Preferably, the crosslinking agent is isocyanate or blocked isocyanate, the heat-resistant lubricant is silicone resin (BYK323), and the adhesion promoter is chlorinated polypropylene resin.

[0039] Preferably, when preparing the substrate coating liquid using the above-mentioned components, the solvent used is a mixed solvent of 2-butanone and toluene in a volume ratio of 5:5, and the mass fraction of the mixed solvent is 30-50 parts.

[0040] This invention ensures coating uniformity and adhesion by controlling the solvent of the back coating liquid and corona treatment of the substrate 1, while controlling the friction coefficient through the textured surface design to adapt to the needs of different printers.

[0041] The back coating 5 consists of fluffy powder and / or silica powder with a particle size of 5-10 μm.

[0042] Preferably, the mass fractions of each component in the back coating layer 5 are: 40-60 parts of waterborne polyurethane resin, 10-20 parts of fluff powder and / or silica powder, 0.5-1 parts of dispersant, and 0.3-0.5 parts of thickener; when the above components are prepared into a coating liquid, the solvent used is an isopropanol aqueous solution with a volume ratio of 1:1, and its mass fraction is 30-50 parts.

[0043] Preferably, the solvent used can also be an aqueous solution of propylene glycol methyl ether in a volume ratio of 1:1.

[0044] Preferably, the waterborne polyurethane resin can be replaced with a waterborne acrylic resin.

[0045] The release layer 2 of the present invention has two functions: first, to provide adhesion to the substrate 1 during printing, so as to prevent the coating from melting and sticking to the ribbon when heated; and second, to provide demolding properties during transfer, so that the subsequent coating can be easily removed and bonded to the substrate.

[0046] Preferably, in the composition of release layer 2, chloroethyl ether resin and chloroethyl acetate resin are selected as the main resins, and the ratio of the two is 1:5 to 1:9 (which can be adjusted according to the release effect), and an appropriate amount of polyester resin is added to optimize the adhesion. When preparing the release layer coating liquid, the above-mentioned main resins are dissolved in a mixed solvent of 2-butanone and toluene in a volume ratio of 5:5.

[0047] Preferably, the solids content in the release coating liquid is 15% by mass.

[0048] The substrate 1 of this invention is a PET film. Before coating, the substrate 1 can undergo pretreatments such as corona discharge or plasma treatment to facilitate adhesion; corona treatment is preferred in this invention. Specifically, the original dyne value of the back side of the PET substrate is approximately 32-35 mN / m, and after corona treatment, the dyne value is greater than 48 mN / m, which can increase the adhesion between the back coating 5 and the substrate 1 by 2-3 times, preventing the back coating 5 from peeling off during printing.

[0049] The thickness of each layer has also been adjusted in this invention. Specifically, the coating thickness of the release layer coating liquid is 0.2-0.8 μm, preferably 0.5 μm; the coating thickness of the support layer coating liquid is 0.7-1.3 μm, preferably 1.0 μm; the coating thickness of the substrate layer coating liquid is 1.5-2.5 μm, preferably 2 μm; the coating thickness of the back coating liquid is 0.7-1.3 μm, preferably 1.0 μm; and the thickness of the substrate 1 is 4.5-100 μm, preferably 12-25 μm.

[0050] If the release layer 2 is too thick (>0.8μm), it will increase the demolding resistance; if it is too thin (<0.2μm), it will result in insufficient adhesion. If the support layer 3 is too thick (>1.3μm), it will affect the contact of the print head; if it is too thin (<0.7μm), it will result in poor dye blocking effect. If the substrate layer 4 is too thick (>2.5μm), it will result in incomplete transfer; if it is too thin (<1.5μm), it will result in insufficient dye carrying capacity. If the back coating layer 5 is too thick (>1.3μm), it will result in fluctuations in the coefficient of friction; if it is too thin (<0.7μm), it will result in insufficient velvet effect.

[0051] The method for preparing the high-performance thermal sublimation retransfer film of the present invention includes the following steps: Release layer coating liquid, support layer coating liquid, substrate coating liquid and back coating liquid are prepared separately. The other side of the substrate 1 is subjected to corona treatment, and then the back coating liquid is coated. After drying, the back coating 5 is obtained. On one side of the substrate 1, the release layer coating liquid, support layer coating liquid and substrate coating liquid are applied in sequence by coating-drying method to prepare each layer.

[0052] Preferably, after corona treatment, the dyne value on the other side of the substrate 1 is greater than 48, which ensures the adhesion of the coating liquid.

[0053] Preferably, the back coating liquid is applied to the other side of the corona-treated substrate 1 using a slot coating method, and the drying temperature is 80-90℃ for 1 hour.

[0054] Preferably, the release layer coating liquid is applied using a 220-mesh anilox roller with a gravure coating process and dried at 100°C.

[0055] Preferably, the support layer coating liquid is applied to the release layer surface using a 150-mesh anilox roller, and the drying temperature is 80-100℃, with a drying time of 1-2 hours.

[0056] Preferably, the substrate coating liquid is applied to the surface of the support layer using a 100-mesh anilox roller, and the drying temperature is 100-120℃ for 1-2 hours.

[0057] The present invention will be illustrated below through specific embodiments and comparative examples.

[0058] Example 1 The specific composition and preparation process of each layer of the high-performance thermal sublimation retransfer film in this embodiment are as follows: Substrate 1 is a 25μm PET film, which is subjected to corona treatment during preparation.

[0059] The coating solution for release layer 2 contains the following components in parts by mass: 2 parts chloroethyl ether resin, 8 parts chloroacetic acid resin, 45 parts 2-butanone, and 45 parts toluene. The coating solution is applied to one side of substrate 1 using a gravure coating method, with a coating thickness of 0.5 μm, and then dried at 100°C.

[0060] The coating solution of the support layer 3 contains the following components by mass: 40 parts water-based PU resin, 8 parts PMMA microparticles (2μm), 2 parts ultramarine pigment, 8 parts alumina sol, 40 parts solvent (water:IPA=1:1), and 0.8 parts dispersant. The coating solution is applied to the release layer 2 using gravure coating to a thickness of 1.0μm, and then dried at 90℃ for 1.5 hours.

[0061] The coating solution for substrate layer 4 contains the following components in parts by mass: 70 parts of high-VC vinyl chloride resin (VC=88%, >86%), 15 parts of high-Tg polyester resin (Tg=85℃), 10 parts of PVB resin, 3 parts of isocyanate, 0.8 parts of silicone resin, 2 parts of chlorinated polypropylene resin, 35 parts of 2-butanone, and 35 parts of toluene. The coating solution is applied to support layer 3 using gravure coating to a thickness of 2.0 μm, and then dried at 110℃ for 1.5 h.

[0062] The coating solution for back coating layer 5 contains the following components by mass: 50 parts waterborne polyurethane resin, 15 parts flocking powder, 0.7 parts dispersant, 0.4 parts thickener, and 40 parts solvent (water:IPA = 1:1). The coating solution is applied to the other side of substrate 1 using a slot coating method. After corona treatment, the other side of substrate 1 has a dyne value of 50. The coating thickness is 1.0 μm, and after drying at 85°C for 1 hour, the resulting back coating layer 5 has a coefficient of friction of 0.5.

[0063] Example 2 The specific composition and preparation process of each layer of the high-performance thermal sublimation retransfer film in this embodiment are as follows: Substrate 1 is a 20μm PET film, which is subjected to corona treatment during preparation.

[0064] The mass fractions of each component in the coating solution of release layer 2 are: 2 parts chloroethyl ether resin, 8 parts chloroacetic acid resin, 45 parts 2-butanone, and 45 parts toluene. The coating solution is applied to one side of substrate 1 using gravure coating to a thickness of 0.6 μm and then dried at 100°C.

[0065] The coating solution of the support layer 3 contains the following components by mass: 35 parts water-based PU resin, 6 parts PMMA microparticles (1μm), 1.5 parts ultramarine pigment, 6 parts alumina sol, 45 parts solvent (water:IPA=1:1), and 0.6 parts dispersant. The coating solution is applied to the release layer 2 using gravure coating to a thickness of 0.9μm, and then dried at 85℃ for 2 hours.

[0066] The coating solution for substrate layer 4 contains the following components by mass: 65 parts of high-VC vinyl chloride resin (VC=87%, >86%), 18 parts of high-Tg polyester resin (Tg=80℃), 12 parts of PVB resin, 2 parts of isocyanate, 0.6 parts of silicone resin, 1.5 parts of chlorinated polypropylene resin, 38 parts of 2-butanone, and 38 parts of toluene. The coating solution is applied to support layer 3 using gravure coating to a thickness of 1.8 μm, and then dried at 100℃ for 2 hours.

[0067] The coating solution for back coating layer 5 contains the following components by mass: 45 parts waterborne polyurethane resin, 12 parts flocking powder, 0.6 parts dispersant, 0.3 parts thickener, and 45 parts solvent (water:IPA = 1:1). The coating solution is applied to the other side of substrate 1 using a slot coating method. After corona treatment, the other side of substrate 1 has a dyne value of 49. The coating thickness is 0.9 μm, and after drying at 80°C for 1 hour, the coefficient of friction for back coating layer 5 is 0.6.

[0068] Example 3 The specific composition and preparation process of each layer of the high-performance thermal sublimation retransfer film in this embodiment are as follows: Substrate 1 is a 25μm PET film, which is subjected to corona treatment during preparation.

[0069] The coating solution for release layer 2 contains the following components in parts by mass: 2 parts chloroethyl ether resin, 8 parts chloroacetic acid resin, 45 parts 2-butanone, and 45 parts toluene. The coating solution is applied to one side of substrate 1 using gravure coating to a thickness of 0.7 μm, and then dried at 100°C.

[0070] The coating solution for support layer 3 contains the following components by mass: 45 parts water-based PU resin, 10 parts PMMA microparticles (3μm), 3 parts ultramarine pigment, 10 parts alumina sol, 35 parts solvent (water:IPA=1:1), and 1 part dispersant. The coating solution is applied to release layer 2 using gravure coating to a thickness of 1.2μm, and then dried at 95℃ for 1 hour.

[0071] The coating solution for substrate layer 4 contains the following components in parts by mass: 75 parts of high-VC vinyl chloride resin (VC=90%, >86%), 12 parts of high-Tg polyester resin (Tg=90℃), 8 parts of PVB resin, 4 parts of isocyanate, 1 part of silicone resin, 3 parts of chlorinated polypropylene resin, 32 parts of 2-butanone, and 32 parts of toluene. The coating solution is applied to support layer 3 using gravure coating to a thickness of 2.2 μm, and then dried at 120℃ for 1 hour.

[0072] The coating liquid for back coating layer 5 contains the following components by mass: 55 parts waterborne polyurethane resin, 18 parts flocking powder, 0.8 parts dispersant, 0.5 parts thickener, and 35 parts solvent (water:IPA = 1:1). The coating liquid is applied to the other side of substrate 1 using a slot coating method. After corona treatment, the other side of substrate 1 has a dyne value of 51. The coating thickness is 1.2 μm, and after drying at 90°C for 1 hour, the coefficient of friction for back coating layer 5 is 0.3.

[0073] Comparative Example 1 In this comparative example, the sublimation retransfer film has no support layer 3, and the main resin in the substrate layer 4 is a common chloroacetic acid resin with a VC content of 45% and a coating thickness of 2.0 μm.

[0074] The substrate 1, release layer 2 and back coating 5 are the same as in Example 1.

[0075] Comparative Example 2 In this comparative example of thermal sublimation retransfer film, the solvent in the coating solution of the support layer 3 is pure deionized water, which does not contain isopropanol, and the rest is exactly the same as in Example 1.

[0076] Comparative Example 3 In this comparative example of thermal sublimation retransfer film, the back side of the PET substrate was not corona treated before the back coating layer 5 was applied, and its dyne value was 35. The rest was the same as in the example.

[0077] Comparative Example 4 In this comparative example of thermal sublimation retransfer film, the coating thickness of the substrate layer 4 is too thick, at 3.0 μm, while the rest is the same as in Example 1.

[0078] Comparative Example 5 In this comparative example of thermal sublimation retransfer film, the coating thickness of release layer 2 is too thick, at 1.0 μm, while the rest is the same as in Example 1.

[0079] The performance of the thermal sublimation retransfer films of the above embodiments and comparative examples was tested, and the specific test plan is as follows: Testing equipment: DTP330 dye-sublimation label printing machine, original ribbon; X-Rite i1-PRO3 colorimeter; coefficient of friction tester (GB / T 10006-2008); 19mm wide 3M SCOTCH tape; dyne pen (for testing the corona effect of the back coating); coating uniformity observation instrument (for observing the coating surface at 200x magnification).

[0080] Test conditions: Printing speed 3m / min; transfer speed 3m / min; transfer temperature 130℃; secondary hot pressing temperature 100℃; test substrates were 60g Xuan paper, PP synthetic paper, and coated paper.

[0081] Test items and evaluation criteria: (1) OD value test: Print a 100% solid dot color block image (6×8 inches), test the density of yellow, magenta, cyan and black, and take the average value.

[0082] (2) Evaluation of printing uniformity: ① Coating uniformity: Observe the coating surface at 200x magnification. No pinholes or streaks are rated A (excellent), slight pinholes are rated B (qualified), and obvious pinholes / streaks are rated C (unqualified); ② Image uniformity: Print a 256-color scale image. Visually observe that no streaks or color difference are rated A, slight streaks are rated B, and obvious streaks / color difference are rated C.

[0083] (3) Whiteness test: The whiteness of the membrane surface is tested using a whiteness meter. ≥85 is A, 75-84 is B, and <75 is C.

[0084] (4) Heat resistance test: The transfer film is kept at a constant temperature of 150℃ for 30 minutes. The coating is A if it is not deformed or yellowed, B if it is slightly deformed, and C if it is severely deformed / yellown.

[0085] (5) Friction coefficient test: The friction coefficient of the back coating is tested according to GB / T 10006-2008. The coefficient is A if it is in the range of 0.2-0.8, and B if it is outside the range.

[0086] (6) Adhesion test: ① Back coating adhesion: Tear the back coating vertically at 90° with 3M tape. No peeling is A, slight peeling is B, and severe peeling is C; ② Substrate adhesion: Tear the substrate after transfer with 3M tape vertically at 90°. No peeling is A, slight peeling is B, and severe peeling is C.

[0087] The test results are shown in Table 1: Table 1 Test results for each embodiment and comparative example As can be seen from the test results in Table 1, the solution of the present invention has the following specific effects: (1) Dual improvement in coating uniformity and OD value: In the coating liquid of the support layer 3, the solvent ratio of water to IPA of 1:1 can effectively avoid excessive tension. The coating uniformity of Examples 1-3 and Comparative Examples 3-4 reached Grade A. In Examples 1-3, with the combination of alumina sol to block dye penetration and VC>86% chloroacetic acid resin with strong absorption capacity, the average OD value reached 2.05, which is more than 25% higher than the prior art (Comparative Examples 1-2).

[0088] (2) Significantly optimized heat resistance: The substrate 4 uses VC>86% chloroacetic acid resin as the main resin, crosslinked with high Tg auxiliary resin and isocyanate, and the heat resistance reaches 150℃ / 30min without deformation (all examples are grade A), which is significantly improved by the lower VC resin scheme (comparative example 1 is grade C).

[0089] (3) The adhesion and compatibility of the back coating 5 are both taken into account: In each embodiment, the other side of the substrate 1 is treated with corona and the dyne value is >48. Combined with the coating liquid of the back coating 5 using 1:1 isopropanol water as solvent, the adhesion of the back coating 5 is ensured to reach Grade A, avoiding the problem of peeling without corona treatment (Comparative Example 3 is Grade C). At the same time, the coefficient of friction can be adjusted to adapt to different printers.

[0090] (4) Layer thickness stability assurance: The thickness of each layer in each embodiment is strictly controlled within the limited range (release layer 0.5±0.3μm, etc.) to avoid performance fluctuations caused by exceeding the range (e.g., the excessive thickness of the substrate layer in Comparative Example 4 leads to a decrease in adhesion, and the excessive thickness of the release layer in Comparative Example 5 leads to a decrease in uniformity).

[0091] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A high-performance thermal sublimation retransfer film, comprising a substrate (1), one side of which is provided with a release layer (2) and a printing-receiving layer (4), and the other side is provided with a back-coating layer (5), characterized in that, A support layer (3) is arranged between the release layer (2) and the printing layer (4), the support layer (3) comprises inorganic sol, water-based resin, whiteness-improving pigment and solid filler in its composition; The inorganic sol is at least one of alumina sol and silica sol, and the water-based resin is at least one of water-based polyurethane resin and water-based epoxy resin.

2. The high performance dye-sublimation retransfer print film of claim 1, wherein, The solid filler is at least one of polymethyl methacrylate microparticle and polystyrene microsphere microparticle.

3. A high performance dye-sublimation retransfer print film according to claim 2, wherein, The particle size of the solid filler is 1-3 μm.

4. The high performance dye-sublimation retransfer print film of claim 2, wherein, The support layer (3) further comprises dispersant in its composition; in the support layer (3), the mass fraction of each component is: 30-50 parts of the water-based resin, 5-10 parts of the solid filler, 1-3 parts of the whiteness-improving pigment, 5-10 parts of the inorganic sol and 0.5-1 part of the dispersant.

5. The high performance dye-sublimation retransfer print film according to any one of claims 1-4, wherein, The printing layer (4) comprises main resin in its composition, and the main resin is chlorovinyl acetate resin with high content of chloroethylene; The chlorovinyl acetate resin comprises chlorovinyl acetate resin and / or chlorovinyl acetate-acrylic acid copolymer, and the mass percentage of chloroethylene is greater than 86%.

6. A high performance dye-sublimation retransfer print according to claim 5, wherein, The printing layer (4) further comprises auxiliary resin in its composition, and the auxiliary resin comprises high-Tg synthetic resin and polyvinyl butyral resin; the mass fraction of each component is: 60-80 parts of the main resin, 10-20 parts of the high-Tg synthetic resin and 10-20 parts of the polyvinyl butyral resin. The high-Tg synthetic resin is polyester resin and / or acrylic resin, and the Tg is greater than or equal to 80℃.

7. A high performance dye-sublimation retransfer print film according to claim 6, wherein, The printing layer (4) further comprises crosslinking agent, heat-resistant lubricant and adhesion promoter in its composition; in the printing layer (4), the mass fraction of each component is: 60-80 parts of the main resin, 10-20 parts of the high-Tg synthetic resin, 10-20 parts of the polyvinyl butyral resin, 1-5 parts of the crosslinking agent, 0.5-1 part of the heat-resistant lubricant and 1-3 parts of the adhesion promoter.

8. A high performance dye-sublimation retransfer print film according to any one of claims 1 to 4, wherein, The back coating layer (5) comprises suede powder and / or silica powder with a particle size of 5-10 μm in its composition.

9. A method of preparing a high performance dye sublimation retransfer film according to any one of claims 1 to 8, characterized in that, The method comprises the following steps: The release layer coating liquid, the support layer coating liquid, the printing layer coating liquid and the back coating layer coating liquid are prepared respectively, wherein the support layer coating liquid comprises the inorganic sol, the water-based resin, the whiteness-improving pigment and the solid filler; The other side of the substrate (1) is subjected to corona treatment, and then the back coating layer coating liquid is coated and dried to obtain the back coating layer (5); The release layer coating liquid, the support layer coating liquid and the printing layer coating liquid are sequentially coated and dried on one side of the substrate (1) to form the layers.

10. The method for preparing a high-performance thermal sublimation retransfer film according to claim 9, characterized in that, After the corona treatment, the dyne value of the other side of the substrate (1) is greater than 48.

11. The method for preparing a high-performance thermal sublimation retransfer film according to claim 9, characterized in that, The solvent of the support layer coating liquid is a mixed solution of isopropyl alcohol and water with a volume ratio of 1:1 or a mixed solution of ethanol and water with a volume ratio of 1:1, and the coating thickness is 0.7-1.3 μm.

12. The method for preparing a high-performance thermal sublimation retransfer film according to claim 9, characterized in that, The solvent in the back coating coating solution is a mixed solution of isopropyl alcohol and water at a volume ratio of 1:1, or a mixed solution of propylene glycol methyl ether and water at a volume ratio of 1:1; the coating thickness is 0.7-1.3 μm.

13. The method for preparing a high-performance thermal sublimation retransfer film according to claim 9, characterized in that, The coating thickness of the release layer coating solution is 0.2-0.8 μm, and the coating thickness of the printing layer coating solution is 1.5-2.5 μm.

Images