Pre-coated composite film transfer printing process

Abstract

A pre-coated composite film transfer printing process, comprising the following steps: S1, release layer coating: coating the surface of a BOPP base film with a release layer solution by using an anilox roll, and performing segmented heating and drying to form a release layer; S2, ink layer coating: coating the release layer obtained in step S1 with a dyeing solution by using the anilox roll, and performing segmented heating and drying to form an ink layer; S3, adhesive layer coating: melting an EVA hot-melt adhesive, then adding hexagonal boron nitride, rosin acid, and white birch tree extract, mixing at 100-200 r / min for 5-10 min, and then coating the ink layer obtained in step S2 with the mixture by using a heated anilox roll; S4, enabling the film coated with the hot-melt adhesive and obtained in step S3 to pass through a cooled anilox roll, curing in an air cooling chamber, and slitting and rolling to obtain a pre-coated composite film; and S5, laminating, by means of hot pressing, the pre-coated composite film obtained in step S4 on the surface of a packaging material. In the process, hexagonal boron nitride, rosin acid, white birch tree extract, and the like are added to an EVA hot-melt adhesive to improve the processability of the EVA hot-melt adhesive, enhancing the bonding effect between a composite film and a print substrate, and achieving simple operation. The prepared pre-coated composite film can satisfy the requirements of thermal transfer printing, has a wide range of applications, and is beneficial to industrial production.

Description

Pre-coated composite film transfer printing process TECHNICAL FIELD

[0001] The present application belongs to the field of thermal transfer film, and particularly relates to a pre-coated composite film transfer printing process. BACKGROUND

[0002] With the continuous development of the domestic printing industry and the improvement of people's living standards, there are higher requirements for the surface pattern decoration of industrial products such as plastics, glass, metal, etc. The original traditional printing method has been unable to meet the needs of surface decoration. Thermal transfer printing, as a new type of printing method, has received widespread attention. Thermal transfer printing is one of the special printing methods and also a type of transfer printing. In essence, it is a method of transferring the graphics and texts pre-printed on the carrier film to the printing surface through a thermal transfer printer under the conditions of heat and pressure. Thermal transfer printing is simple, fast, and pollution-free, and the transferred pattern is clear, bright in color, and distinct in layers. At the same time, it has good adhesion, high decorative value, improves the grade and added value of the product, and is suitable for mass production, which can be widely used in the surface processing of various industrial products such as plastics, glass, metal, and wood. In the thermal transfer printing method, the most core technology is the thermal transfer film. The thermal transfer film is a functional film that separates the adhesive and ink layer from the protective layer under the action of heat and pressure and adheres to the surface of the printing surface. The thermal transfer film is a composite film, which generally has an adhesive layer, an ink layer, a protective layer, a separation layer, and a base layer.

[0003] BOPP film is a multi-layer co-extruded film, which is made by co-extruding polypropylene particles into a sheet and then stretching in the longitudinal and transverse directions. Due to the molecular orientation of the stretching, BOPP film has good physical stability, mechanical strength, air tightness, high transparency and gloss, and is tough and wear-resistant, so it is widely used as a printing film and is known as the "packaging queen". Based on these characteristics, BOPP film can be an effective candidate for thermal transfer film base film. However, the surface tension of BOPP film often needs to be above 38 mN / m during printing, compounding, coating, etc. However, polypropylene is a non-polar polymer, and the surface tension value is relatively low, so the surface of the BOPP film needs to be treated to improve its surface tension and improve the adhesion and wettability of the polymer to meet the use requirements.

[0004] CN 103707603 A discloses a double-sided heat-seal double-sided anti-fog type BOPP film and a preparation method thereof. The film is composed of an inner surface layer, a core layer and an outer surface layer. The inner surface layer and the outer surface layer are composed of polypropylene and an anti-sticking agent. The mass percentage of each component in the inner surface layer and the outer surface layer is as follows: polypropylene 97.5-98.5%, anti-sticking agent 1.5-2.5%. The core layer is composed of polypropylene, an anti-fog agent and a slip agent. The mass percentage of each component in the core layer is as follows: polypropylene 95.9-97.1%, anti-fog agent 2.5-3.5%, slip agent 0.4-0.6%. The anti-fog agent is composed of the following components in the following weight percentages: sorbitan monostearate 50%, glycerol monooleate 35%, polyethylene glycol (20) glycerol monostearate 15%. The double-sided heat-seal double-sided anti-fog type BOPP film prepared by the invention has significantly improved hydrophilicity and anti-fog performance.

[0005] CN 105774283 A discloses a smooth elastic heat transfer film and a preparation method thereof. The film comprises a BOPP base film, a smooth layer and an elastic layer coated on the BOPP base film in sequence. The thickness of the BOPP base film is 20-25 μm. The BOPP base film with this thickness has high tensile strength, toughness and dye wetting property suitable for printing. The smooth layer is composed of polyurethane resin, silicone oil and butanone, which can make the surface of the heat transfer film smooth after hot stamping, and significantly improve the scratch resistance and wear resistance. In addition, the smooth layer also has peeling performance, which can separate the elastic layer from the BOPP base film. The elastic layer can make the heat transfer film have different colors, and has elasticity and stretchability. After hot stamping and heat transfer, the elastic fabric surface layer is smooth, scratch-resistant and wear-resistant, and the color layer is continuous, which improves the appearance, comfort and service life of the fabric.

[0006] CN 106564256 A discloses a forming method for printing film combined with high-brightness particle film integrated alignment overprint. The steps include BOPP base film, ink color matching, ink printing, cooling and winding, and hot pressing processing. The ink printing adopts intaglio printing method. First, a group of one-color method is used to print ink on the base film and dry and cure until the printing and drying and curing of all color groups are completed. Then, hot melt adhesive or solvent type adhesive is melted and coated on the last group of high solid plate with patterns, and the adhesive is overprinted on the corresponding patterns in an alignment manner to form a group of integrally formed base film with preset patterns.

[0007] SUMMARY

[0008] In view of the defects of the prior art, the present application discloses a kind of pre-coated composite film transfer printing process, by BOPP base film, polysiloxane off layer, ink layer, EVA hot melt adhesive bonding layer is made into pre-coated composite film, hot pressing on the object that should bear can, without coating glue in printing process, reduce the printing time, while, environmental protection is pollution-free. By adopting hexagonal boron nitride, rosin acid, white birch extract and so on are added to EVA hot melt adhesive to improve the processing performance of EVA hot melt adhesive, enhance the adhesion of composite film and package.

[0009] In order to achieve the above-mentioned purpose, the present application provides a kind of pre-coated composite film transfer printing process, steps are as follows:

[0010] S1 off layer coating: off layer liquid is coated on the surface of BOPP base film with anilox roll, and is dried by subsection heating to form off layer;

[0011] S2 ink layer coating: dyeing liquid is coated on the off layer obtained in step S1 with anilox roll, and is dried by subsection heating to form ink layer;

[0012] S3 bonding layer coating: EVA hot melt adhesive is melted, hexagonal boron nitride, rosin acid and white birch extract are added, mixed at 100-200 r / min for 5-10 min, and then coated on the ink layer obtained in step S2 with heated anilox roll;The mass of the hexagonal boron nitride is 0.5-1% of the EVA hot melt adhesive;The mass of the rosin acid is 1-3% of the EVA hot melt adhesive;The mass of the white birch extract is 10-30% of the EVA hot melt adhesive;

[0013] S4: the film coated with hot melt adhesive obtained in step S3 is passed through a cooling anilox roll, solidified by a cold air box, cut and wound, to obtain a pre-coated composite film;

[0014] S5: the pre-coated composite film is hot pressed on the surface of the packaging material.

[0015] Preferably, in the off layer liquid of step S1, the mass ratio of each substance is 1-10% protective agent, 10-15% cellulose acetate, 0.05-0.2% leveling agent, and the rest is organic solvent.

[0016] The protective agent is one, a combination of two or more of hexamethyldisiloxane, tetraethenyltetramethylcyclotetrasiloxane and octamethylcyclotetrasiloxane.

[0017] The leveling agent is a polyether siloxane copolymer type leveling agent.

[0018] The organic solvent is one, a combination of two or more of acetone, butanone, 3-pentanone, cyclohexanone and toluene.

[0019] The mesh number of the anilox roll in steps S1-S4 is independently 100-250.

[0020] The thickness of the BOPP film is 15-25 μm, and the width is 1000-2000 mm.

[0021] The thickness of the release layer is 10-20 μm.

[0022] In the present application, the release layer not only has a protective effect on the ink layer, but also separates after thermal transfer printing, and directly appears on the surface of the printing substrate. However, due to the need for easy peeling, the surface polarity of the release layer is low, the surface energy is low, and in the coating process, it is difficult to wet and cause poor leveling, which directly affects the appearance and gloss of the final printing substrate surface and even the performance. The present application adds organosiloxane to reduce the surface energy and viscosity of the release layer, to improve the wettability and leveling of the coating during coating, and to enhance the hand feeling of the printed matter. However, the release layer also needs to be coated with an ink layer, and organosiloxane has a serious uneven distribution and migration phenomenon during film formation, which gradually destroys the hydrophobic structure. By polymerizing organosiloxane with cyclic siloxane, polysiloxane can be prepared, which has more functional groups and more excellent surface properties.

[0023] Further preferably, the protective agent in step S1 is a methyl vinyl siloxane polymer, and the preparation method is as follows: octamethylcyclotetrasiloxane, tetraethenyltetramethylcyclotetrasiloxane, and hexamethyldisiloxane are mixed and stirred at a temperature of 60-80°C and a rotation speed of 200-500 r / min for 10-30 min, a catalyst is added in an amount of 1-2% of the total mass of the mixed siloxane, and then reacted at 60-80°C for 5-10 h; naturally cooled to 20-30°C, and then sodium carbonate is added to adjust the pH to 7.0-8.0; dried at 70-90°C for 5-10 h to obtain the methyl vinyl siloxane polymer.

[0024] The catalyst is one or a combination of triflic acid and phosphoric acid.

[0025] Most preferably, the mass ratio of triflic acid to phosphoric acid in the catalyst is (3-5):1.

[0026] Preferably, the mass ratio of each substance in the ink layer solution in step S2 is 10-20% water-based dye, 20-30% water-based polyurethane resin, 0.2-0.5% defoaming agent, 0.2-0.5% antistatic agent, 0.2-0.5% leveling agent, and the rest is cyclohexanone.

[0027] The defoaming agent is an organic silicon defoaming agent.

[0028] The antistatic agent is one, a combination of two or more of a sulfuric acid derivative type, a phosphoric acid derivative type, an amine type, a quaternary ammonium salt type, an imidazole type, and an oxirane derivative type antistatic agent.

[0029] The leveling agent is a fluorocarbon-modified polyacrylate leveling agent.

[0030] The thickness of the dye layer is 20–50 μm.

[0031] The segmented heating temperatures described in steps S1 to S2 are each independently T170℃, T275℃, T380℃, and T485℃.

[0032] Preferably, the melting temperature of the EVA hot melt adhesive in step S3 is 130-150°C.

[0033] Preferably, the preparation method of the birch extract is as follows: the birch bark is dried in a nitrogen atmosphere at 240-320°C for 1-5 hours; the dried birch bark is added to acetone and extracted by Soxhlet extractor for 5-12 hours, and the solvent is removed to obtain the birch extract.

[0034] The temperature of the heated anilox roller is 70-90℃.

[0035] The thickness of the adhesive layer is 0.01 to 0.5 mm.

[0036] In actual production, different graphic patterns are designed in the ink layer, which means that the ink layer does not completely cover the release layer. In this case, the adhesive layer is in direct contact with the release layer, which places high demands on the performance of the adhesive layer. It must have strong adhesion to both the ink layer and the release layer, as well as good adhesion to the substrate. However, these three layers have significant differences in structure and properties. Some technologies apply an additional coating layer between the ink layer and the adhesive layer. This coating layer has good adhesion to the release layer, ink layer, and adhesive layer, so the adhesive layer only needs to interact with the substrate and the newly added coating. However, this operation increases the number of steps and costs, and does not meet the need for thinner packaging materials. Enhancing the interaction between the adhesive layer, ink layer, and release layer is a more suitable method. The adhesive layer of this invention uses EVA hot melt adhesive, which is solid at room temperature and transforms into a flowable liquid adhesive with a certain viscosity when heated to a certain temperature. After application, it can cool and cure in a very short time. EVA hot melt adhesive is non-toxic and pollution-free, and has good optical properties, flexibility, processability and chemical corrosion resistance, but it has shortcomings such as poor adhesion, poor wettability and poor material compatibility.

[0037] Hexagonal boron nitride is a two-dimensional material composed of alternating sp... 2 Composed of hybrid boron and nitrogen atoms, with a structure similar to graphite, it not only serves as an effective heat dissipation film due to its high in-plane thermal conductivity, but also enhances optical transparency due to its large band gap energy. Adding hexagonal boron nitride to EVA hot melt adhesive can improve its mechanical strength and thermal conductivity.

[0038] However, the uniformity, adhesion quality of hexagonal boron nitride in EVA hot melt adhesive is not ideal, the interaction force is poor, which not only leads to insufficient mechanical stability, but also leads to high thermal resistance between hexagonal boron nitride and film layer, hindering effective heat conduction. Peeling off hexagonal boron nitride and reducing its size can enhance its dispersion. Ball milling can effectively peel off and functionalize hexagonal boron nitride, and adding a grinding protective agent can prevent mechanical damage to hexagonal boron nitride.

[0039] Most preferably, the hexagonal boron nitride in step S3 is replaced by modified hexagonal boron nitride; the preparation method of the modified hexagonal boron nitride is: 1 part by weight of hexagonal boron nitride and 15-20 parts by weight of urea are ball milled at a speed of 500-1000 r / min for 5-10 h; after ball milling, the powder is placed in water and stirred at a speed of 300-500 r / min for 5-10 min, the urea is dissolved, then centrifuged at 8000-10000 r / min, washed with ethanol and water three times respectively, and the insoluble material is dried at 80-100℃ for 5-10 h to obtain modified hexagonal boron nitride.

[0040] Preferably, the temperature of the cooling anilox roller in step S4 is 15-30℃, and the temperature of the cold air box is 15-30℃.

[0041] The beneficial effects obtained by the present application are:

[0042] (1) The protective agent is added to the interlayer, which has a thinning effect on the composite transfer film without additional protective layer construction, meets the needs of energy saving and emission reduction and clean production, and has a synergistic effect with siloxane when modified hexagonal boron nitride is added to EVA hot melt adhesive, significantly enhancing the adhesion of the composite film to the printing material. The pre-coated composite film method of the present application is simple to operate, and the pre-coated composite film produced can meet the needs of thermal transfer printing, has a wide range of applications, and is conducive to industrial production.

[0043] (2) By using EVA hot melt adhesive to pre-coat on the film to form a bonding layer, it can be directly heated and printed on the product, without the need for coating glue during printing, which reduces the printing time and is environmentally friendly and pollution-free.

[0044] (3) The EVA hot melt adhesive is improved by using rosin acid and birch extract, which can effectively improve the melting index of EVA sol, i.e. the fluidity of EVA hot melt adhesive is significantly improved, which helps to improve the wetting performance and adhesion ability of EVA hot melt adhesive. DETAILED DESCRIPTION

[0045] Part of the raw materials in the embodiments of the present application are introduced as follows:

[0046] BOPP film, 25 μm thick, 1500 mm wide, purchased from Dalian Huiming Packaging Material Co., Ltd.

[0047] Water-based dye, purchased from Jinan Hangran Trading Co., Ltd.

[0048] Water-based polyurethane resin, model JU-5015, purchased from Guangdong Shunde Jutu High Polymer Material Co., Ltd.

[0049] Hexagonal boron nitride, content ≥ 99%, purchased from Tianyuan Aviation Material (Yingkou) Technology Co., Ltd.

[0050] The remaining unmentioned raw materials are materials commonly used in the art, and the grade is industrial grade or above industrial grade.

[0051] In order to make the purpose, technical scheme and advantages of the present application clearer and more apparent, the present application will be further described in detail below in conjunction with examples. It should be understood that the specific examples described herein are only used to explain the present application and not to limit the present application. In addition, the technical features involved in each embodiment of the present application described below can be combined with each other as long as they do not conflict with each other.

[0052] Example 1

[0053] The pre-coated composite film transfer process comprises the following steps:

[0054] S1 inject the delamination liquid into the trough, and coat the liquid on the surface of the BOPP base film with a thickness of 25 μm and a width of 1500 mm by a 150 mesh anilox roller, dry through four ovens T170℃, T275℃, T380℃, T485℃, to form a delamination layer with a thickness of 20 μm;

[0055] S2 inject the water-based dye, cyclohexanone, water-based polyurethane resin, defoaming agent, antistatic agent, and leveling agent into the trough, and coat the liquid on the delamination layer obtained in step S1 by a 150 mesh anilox roller, dry through four ovens T170℃, T275℃, T380℃, T485℃, to form an ink layer with a thickness of 30 μm;

[0056] S3 melt the EVA hot melt adhesive at 150℃, and coat the EVA hot melt adhesive on the ink layer obtained in step S2 by a 150 mesh 80℃ heating anilox roller;

[0057] S4 pass the film coated with hot melt adhesive obtained in step S3 through a 150 mesh 25℃ cooling anilox roller, and cure the hot melt adhesive in a cold air box at 25℃ to obtain a composite film containing a bonding layer with a thickness of 0.05 mm; and cut and roll to obtain a pre-coated composite film;

[0058] S5 hot press the pre-coated composite film obtained in step S4 on the surface of the packaging material.

[0059] The mass percentage of each substance in the off-layer solution in step S1 is 3% octamethylcyclotetrasiloxane, 15% cellulose acetate, 81.7% cyclohexanone, and 0.3% polyether siloxane copolymer leveling agent;

[0060] The mass percentage of each substance in the ink layer solution in step S2 is 15% aqueous dye, 25% aqueous polyurethane resin, 0.2% silicone defoamer, 0.2% quaternary ammonium salt antistatic agent, 0.2% fluorocarbon modified polyacrylate leveling agent, and 59.4% cyclohexanone.

[0061] Example 2

[0062] The pre-coated composite film transfer process includes the following steps:

[0063] S1: The off-layer solution is injected into the tank, and the solution is coated on the surface of the BOPP base film with a thickness of 25 μm and a width of 1500 mm by a 150 mesh anilox roll. After passing through four ovens at T170°C, T275°C, T380°C, and T485°C, the solution is dried to form an off-layer with a thickness of 20 μm.

[0064] S2: The aqueous dye, cyclohexanone, aqueous polyurethane resin, defoamer, antistatic agent, and leveling agent are injected into the tank, and the solution is coated on the off-layer obtained in step S1 by a 150 mesh anilox roll heated at 80°C. After passing through four ovens at T170°C, T275°C, T380°C, and T485°C, the solution is dried to form an ink layer with a thickness of 30 μm.

[0065] S3: The EVA hot melt adhesive is melted at 150°C, and the EVA hot melt adhesive is coated on the ink layer obtained in step S2 by a 150 mesh anilox roll heated at 80°C.

[0066] S4: The film coated with the hot melt adhesive obtained in step S3 is passed through a 150 mesh cooling anilox roll at 25°C, and the hot melt adhesive is cured in a cold air box at 25°C to obtain a composite film containing a bonding layer with a thickness of 0.05 mm. The pre-coated composite film of this embodiment is obtained by slitting and winding.

[0067] S5: The pre-coated composite film obtained in step S4 is hot pressed on the surface of the packaging material.

[0068] The mass percentage of each substance in the off-layer solution in step S1 is 3% octamethylcyclotetrasiloxane, 15% cellulose acetate, 81.7% cyclohexanone, and 0.3% polyether siloxane copolymer leveling agent;

[0069] The mass percentage of each substance in the ink layer solution in step S2 is 15% aqueous dye, 25% aqueous polyurethane resin, 0.2% silicone defoamer, 0.2% quaternary ammonium salt antistatic agent, 0.2% fluorocarbon modified polyacrylate leveling agent, and 59.4% cyclohexanone.

[0070] Example 3

[0071] The pre-coated composite film transfer printing process comprises the following steps:

[0072] S1: inject the release layer liquid into the tank, and coat the liquid on the surface of the BOPP base layer film with a thickness of 25 μm and a width of 1500 mm by using a 150 mesh anilox roller, and dry it through four-stage ovens at T170℃, T275℃, T380℃, and T485℃ to form a release layer with a thickness of 20 μm;

[0073] S2: inject the water-based dye, cyclohexanone, water-based polyurethane resin, defoaming agent, antistatic agent, and leveling agent into the tank, and coat the liquid on the release layer obtained in step S1 by using a 150 mesh anilox roller heated at 80℃, and dry it through four-stage ovens at T170℃, T275℃, T380℃, and T485℃ to form an ink layer with a thickness of 30 μm;

[0074] S3: melt the EVA hot melt adhesive at 150℃, and coat the EVA hot melt adhesive on the ink layer obtained in step S2 by using a 150 mesh anilox roller heated at 80℃;

[0075] S4: pass the film coated with the hot melt adhesive obtained in step S3 through a 150 mesh cooling anilox roller at 25℃, and solidify the hot melt adhesive in a cold air box at 25℃ to obtain a composite film containing a bonding layer with a thickness of 0.05 mm; and cut and roll to obtain a pre-coated composite film;

[0076] S5: hot-press the pre-coated composite film obtained in step S4 on the surface of the packaging material.

[0077] The mass percentage of each substance in the release layer liquid in step S1 is 3% tetraethenyltetramethylcyclotetrasiloxane, 15% cellulose acetate, 81.7% cyclohexanone, and 0.3% polyether siloxane copolymer leveling agent;

[0078] The mass percentage of each substance in the ink layer liquid in step S2 is 15% water-based dye, 25% water-based polyurethane resin, 0.2% silicone defoaming agent, 0.2% quaternary ammonium salt antistatic agent, 0.2% fluorocarbon modified polyacrylate leveling agent, and 59.4% cyclohexanone.

[0079] Example 4

[0080] The pre-coated composite film transfer printing process comprises the following steps:

[0081] S1: inject the release layer liquid into the tank, and coat the liquid on the surface of the BOPP base layer film with a thickness of 25 μm and a width of 1500 mm by using a 150 mesh anilox roller, and dry it through four-stage ovens at T170℃, T275℃, T380℃, and T485℃ to form a release layer with a thickness of 20 μm;

[0082] S2 The aqueous dye, cyclohexanone, aqueous polyurethane resin, defoaming agent, antistatic agent, leveling agent are injected into the tank, and the material liquid is coated on the obtained separation layer in step S1 by 150 mesh anilox roller with material liquid, dried by four-stage oven T170℃, T275℃, T380℃, T485℃, to form an ink layer, and the thickness of the ink layer is 30μm;

[0083] S3 The EVA hot melt adhesive is melted at 150℃, and the EVA hot melt adhesive is coated on the ink layer obtained in step S2 by 150 mesh 80℃ heating anilox roller;

[0084] S4 The film coated with hot melt adhesive obtained in step S3 is passed through a 150 mesh 25℃ cooling anilox roller, and the hot melt adhesive is cured in a cold air box at 25℃ to obtain a composite film containing a bonding layer, and the thickness of the bonding layer is 0.05mm; and the pre-coated composite film is cut and wound.

[0085] S5 The pre-coated composite film in step S4 is hot pressed on the surface of the packaging material.

[0086] The mass percentage of each substance in the separation layer material liquid in step S1 is 3% methyl vinyl siloxane polymer, 15% cellulose acetate, 81.7% cyclohexanone, and 0.3% polyether siloxane copolymer leveling agent.

[0087] The preparation method of the methyl vinyl siloxane polymer is as follows: octamethylcyclotetrasiloxane, tetraethenyltetramethylcyclotetrasiloxane, and hexamethyldisiloxane are mixed and stirred at a temperature of 70℃ and a rotation speed of 300r / min for 20min, a catalyst is added in an amount of 1.5% of the total mass of the mixed siloxane, and then reacted at 70℃ for 80h; naturally cooled to 25℃, and sodium carbonate is added to adjust the pH to 7.0; dried at 80℃ for 6h to obtain the methyl vinyl siloxane polymer.

[0088] The catalyst is phosphoric acid.

[0089] The mass percentage of each substance in the ink layer material liquid in step S2 is 15% aqueous dye, 25% aqueous polyurethane resin, 0.2% silicone defoaming agent, 0.2% quaternary ammonium salt antistatic agent, 0.2% fluorocarbon modified polyacrylate leveling agent, and 59.4% cyclohexanone.

[0090] Example 5

[0091] The pre-coated composite film transfer process is basically the same as that of Example 4, except that the preparation method of the methyl vinyl siloxane polymer in the separation layer material liquid is different.

[0092] The preparation method of the methyl vinyl siloxane polymer is as follows: octamethylcyclotetrasiloxane, tetra-vinyl tetramethylcyclotetrasiloxane, and hexamethyldisiloxane are mixed and stirred at a temperature of 70°C and a rotation speed of 300 r / min for 20 min, 1.5% of a catalyst is added to the total mass of the mixed oxygen silane, and then the mixture is reacted at 70°C for 80 h; the mixture is naturally cooled to 25°C, sodium carbonate is added to adjust the pH to 7.0; and the mixture is dried at 80°C for 6 h to obtain the methyl vinyl siloxane polymer.

[0093] The catalyst is triflic acid.

[0094] Example 6

[0095] The pre-coated composite film transfer process is basically the same as that in Example 4, except that the preparation method of the methyl vinyl siloxane polymer in the delamination solution is different.

[0096] The preparation method of the methyl vinyl siloxane polymer is as follows: octamethylcyclotetrasiloxane, tetra-vinyl tetramethylcyclotetrasiloxane, and hexamethyldisiloxane are mixed and stirred at a temperature of 70°C and a rotation speed of 300 r / min for 20 min, 1.5% of a catalyst is added to the total mass of the mixed oxygen silane, and then the mixture is reacted at 70°C for 80 h; the mixture is naturally cooled to 25°C, sodium carbonate is added to adjust the pH to 7.0; and the mixture is dried at 80°C for 6 h to obtain the methyl vinyl siloxane polymer.

[0097] The catalyst is a mixture of triflic acid and phosphoric acid, and the mass ratio of triflic acid to phosphoric acid is 3:1.

[0098] Example 7

[0099] The pre-coated composite film transfer process comprises the following steps:

[0100] S1: The delamination solution is injected into a trough, and the solution is coated on the surface of a BOPP base film with a thickness of 25 μm and a width of 1500 mm by a 150-mesh anilox roller, and then dried by four-stage ovens T170°C, T275°C, T380°C, and T485°C to form a delamination layer with a thickness of 20 μm;

[0101] S2: The aqueous dye, cyclohexanone, aqueous polyurethane resin, defoaming agent, antistatic agent, and leveling agent are injected into a trough, and the solution is coated on the delamination layer obtained in step S1 by a 150-mesh anilox roller, and then dried by four-stage ovens T170°C, T275°C, T380°C, and T485°C to form an ink layer with a thickness of 30 μm;

[0102] S3 melt the EVA hot melt adhesive at 150℃, mix the EVA hot melt adhesive and 0.5% of the modified hexagonal boron nitride by weight of the EVA hot melt adhesive at a speed of 100r / min for 5min to obtain a mixed adhesive; use a 150-mesh 80℃ heating anilox roller to coat the mixed adhesive on the ink layer obtained in step S2;

[0103] S4 pass the film coated with the hot melt adhesive obtained in step S3 through a 150-mesh 25℃ cooling anilox roller, and solidify the hot melt adhesive in a cold air box at 25℃ to obtain a composite film containing a bonding layer, wherein the bonding layer has a thickness of 0.05mm; slit and roll up to obtain a pre-coated composite film;

[0104] S5 hot-press the pre-coated composite film obtained in step S4 on the surface of a packaging material.

[0105] In step S1, the mass percentage of each substance in the delamination solution is 3% methylvinylsiloxane polymer, 15% cellulose acetate, 81.7% cyclohexanone, and 0.3% polyether siloxane copolymer leveling agent;

[0106] The preparation method of the methylvinylsiloxane polymer is the same as that in Example 6;

[0107] In step S2, the mass percentage of each substance in the ink solution is 15% water-based dye, 25% water-based polyurethane resin, 0.2% silicone defoamer, 0.2% quaternary ammonium salt antistatic agent, 0.2% fluorocarbon modified polyacrylate leveling agent, and 59.4% cyclohexanone.

[0108] Example 8

[0109] The pre-coated composite film transfer process comprises the following steps:

[0110] S1 inject the delamination solution into a trough, and use a 150-mesh anilox roller to coat the solution on the surface of a BOPP base film with a thickness of 25μm and a width of 1500mm, and pass through four ovens at T170℃, T275℃, T380℃, and T485℃ for drying to form a delamination layer with a thickness of 20μm;

[0111] S2 inject the water-based dye, cyclohexanone, water-based polyurethane resin, defoamer, antistatic agent, and leveling agent into a trough, and use a 150-mesh anilox roller to coat the solution on the delamination layer obtained in step S1, and pass through four ovens at T170℃, T275℃, T380℃, and T485℃ for drying to form an ink layer with a thickness of 30μm;

[0112] S3 melt the EVA hot melt adhesive at 150℃, mix the EVA hot melt adhesive and 0.5% of the modified hexagonal boron nitride by weight of the EVA hot melt adhesive at a speed of 100r / min for 5min to obtain a mixed adhesive; use a 150-mesh 80℃ heating anilox roller to coat the mixed adhesive on the ink layer obtained in step S2;

[0113] S4 passed the film coated with hot melt adhesive obtained in step S3 through a 150 mesh 25℃ cooling anilox roller, and cured the hot melt adhesive in a cold air box at 25℃ to obtain a composite film containing a bonding layer, the bonding layer having a thickness of 0.05mm; and cut and rolled to obtain a pre-coated composite film;

[0114] S5 hot-pressed the pre-coated composite film obtained in step S4 on the surface of the packaging material.

[0115] The mass percentage of each substance in the delamination material solution in step S1 was 3% methylvinylsiloxane polymer, 15% cellulose acetate, 81.7% cyclohexanone, and 0.3% polyether siloxane copolymer leveling agent;

[0116] The preparation method of the methylvinylsiloxane polymer was the same as that in Example 6.

[0117] The mass percentage of each substance in the ink layer solution in step S2 was 15% water-based dye, 25% water-based polyurethane resin, 0.2% silicone defoamer, 0.2% quaternary ammonium salt antistatic agent, 0.2% fluorocarbon modified polyacrylate leveling agent, and 59.4% cyclohexanone.

[0118] The preparation method of the modified hexagonal boron nitride in step S3 was as follows: 1 part by weight of hexagonal boron nitride and 20 parts by weight of urea were ball milled at a speed of 800 r / min for 8 h; after ball milling, the powder was stirred in water at a speed of 300 r / min for 5 min to dissolve the urea, then centrifuged at 8000 r / min, and washed with ethanol and water three times each; the insoluble material was dried at 80℃ for 6 h to obtain the modified hexagonal boron nitride.

[0119] Example 9

[0120] The pre-coated composite film transfer printing process included the following steps:

[0121] S1 injected the delamination material solution into a trough, and coated the material solution on the surface of a BOPP base film with a thickness of 25μm and a width of 1500mm using a 150 mesh anilox roller; dried through four ovens at T170℃, T275℃, T380℃, and T485℃ to form a delamination layer with a thickness of 20μm;

[0122] S2 injected the water-based dye, cyclohexanone, water-based polyurethane resin, defoamer, antistatic agent, and leveling agent into a trough, and coated the material solution on the delamination layer obtained in step S1 using a 150 mesh anilox roller; dried through four ovens at T170℃, T275℃, T380℃, and T485℃ to form an ink layer with a thickness of 30μm;

[0123] S3 melt EVA hot melt adhesive at 150℃, mix hot melt adhesive, 0.5% of modified hexagonal boron nitride by weight of EVA hot melt adhesive, 2% of rosin acid by weight of EVA hot melt adhesive, 25% of birch extract by weight of EVA hot melt adhesive at 100r / min for 5min to obtain mixed adhesive, coat the mixed adhesive on the ink layer obtained in step S2 by using 150 mesh 80℃ heating anilox roller to coat the mixed adhesive on the ink layer obtained in step S2;

[0124] S4 pass the film coated with hot melt adhesive obtained in step S3 through a 150 mesh 25℃ cooling anilox roller, solidify the hot melt adhesive in a cold air box at 25℃ to obtain a composite film containing a bonding layer, the bonding layer has a thickness of 0.05mm; slit and roll up to obtain a pre-coated composite film;

[0125] S5 hot press the pre-coated composite film on the surface of the packaging material.

[0126] The mass percentage of each substance in the layer separation solution in step S1 is 3% methylvinylsiloxane polymer, 15% cellulose acetate, 81.7% cyclohexanone, and 0.3% polyether siloxane copolymer leveling agent;

[0127] The preparation method of the methylvinylsiloxane polymer is the same as that in Example 6;

[0128] The mass percentage of each substance in the ink layer solution in step S2 is 15% water-based dye, 25% water-based polyurethane resin, 0.2% silicone defoamer, 0.2% quaternary ammonium salt antistatic agent, 0.2% fluorocarbon modified polyacrylate leveling agent, and 59.4% cyclohexanone.

[0129] The preparation method of the modified hexagonal boron nitride in step S3 is as follows: 1 part by weight of hexagonal boron nitride and 20 parts by weight of urea are ball milled at a speed of 800r / min for 8h; after ball milling, the powder is stirred in water at a speed of 300r / min for 5min to dissolve the urea, then centrifuged at 8000r / min, and washed with ethanol and water three times each; the insoluble substance is dried at 80℃ for 6h to obtain the modified hexagonal boron nitride.

[0130] The preparation method of the birch extract is as follows: 100g of birch bark is baked at 280℃ for 2h in a nitrogen atmosphere, 50g of the baked birch bark is added to 200mL of acetone, and the extraction is carried out at 56℃ for 8h by using a Soxhlet extractor, and the obtained extract solution is removed to obtain the birch extract.

[0131] Test Example 1: Test of water permeability and mechanical properties of transfer film

[0132] The water permeability and mechanical strength of the transfer film are important indicators for evaluating the performance of the transfer film, and the pre-coated composite film prepared in step S4 of Examples 6-8 of the present application is tested for water permeability and mechanical strength:

[0133] The water vapor permeability of the transfer film was determined according to the national standard GB / T 26253-2010 "Determination of water vapour transmission rate of plastics films and sheets infrared detector method".

[0134] The tear strength of the transfer film was determined according to the national standard GB / T 16578.1-2008 "Determination of the tear resistance of plastics films and sheets Part 1: trouser tear method".

[0135] Table 1 Water vapor permeability and mechanical properties of the transfer film

[0136] The test results of Examples 6-8 are shown in Table 1. From the test results in Table 1, it can be seen that after adding hexagonal boron nitride to the adhesive layer, the water vapor permeability decreases and the tear strength increases; in Example 8, modified hexagonal boron nitride is added, and these changes are more significant. This may be because the two-dimensional planar structure of hexagonal boron nitride has a barrier effect on water vapor, and the presence of hexagonal boron nitride with high mechanical strength in the adhesive layer improves the strength of the transfer film. In addition, the modified hexagonal boron nitride obtained by ball milling and exfoliation has a smaller size, increases the oxygen-containing functional groups of hexagonal boron nitride, improves the dispersibility in the adhesive layer, and enhances the interaction between the adhesive layer and the ink layer, making the contact more firm. Therefore, the transfer film prepared by adding modified hexagonal boron nitride to the adhesive layer has the lowest water vapor permeability and the highest tear strength.

[0137] Test Example 2 Test of printing performance of the transfer film

[0138] After the pre-coated composite film is heat transferred printed, it is transferred to the surface of the receiving object, the release layer is separated, and the ink layer is directly presented. The hardness, gloss, and adhesion of the ink layer after transfer printing are the main indicators for evaluating the performance of the transfer film.

[0139] The pre-coated composite film of step S4 in the example was transferred to the surface of a flat plate ABS plastic at 150°C, and the release layer was torn off.

[0140] According to the national standard GB / T 6739-2006 "Determination of film hardness of paint by pencil method", the hardness of the ink layer transferred on the ABS plastic was determined.

[0141] According to the national standard GB / T 9754-2007 "Determination of specular gloss of paint film not containing metallic pigments at 20°, 60° and 85°", the gloss of the ink layer transferred on the ABS plastic was determined by a reflectometer at a geometric angle of 60°.

[0142] Table 2 Hardness and gloss of the ink layer after transfer

[0143] Hardness standard:

[0144] Glossiness: The higher the glossiness, the brighter the surface.

[0145] From the test results in Table 2, it can be seen that the addition of methyl vinyl siloxane polymer in the release layer can increase the hardness of the ink layer by two grades (from HB→H), which may be that the organic silicon chain and the medium vinyl species of the methyl vinyl siloxane polymer are prone to phase separation and significantly transfer to the surface of the ink layer, enriching the uniform organic silicon layer, which plays a role in improving the mechanical properties of the surface. The glossiness of Example 4 reached 83.2°, which is because the methyl vinyl siloxane polymer has lower surface energy for siloxane monomers, improving the reflection of light.

[0146] Example 6 uses triflic acid and phosphoric acid as catalysts to prepare methyl vinyl siloxane polymer as a release layer protective agent, and the hardness of the ink layer after transfer is 2H, and the glossiness is 92.3°, which may be that the mixed catalyst system makes the methyl vinyl siloxane polymer surface have more functional groups, stronger permeability to the ink layer, and lower surface tension, further improving the hardness and glossiness of the ink layer.

[0147] According to the national standard GB T 9286-1998 "Cross-hatch test for paint films", the adhesion of the ink layer transferred on ABS plastic was tested by cross-hatch method.

[0148] Table 3 Adhesion grade of ink layer

[0149] Adhesion reflects the adhesion of the ink printed on the surface of the substrate to the substrate. Adhesion classification usually has 6 grades in total, and the lower the classification, the better the adhesion. For general use, the first three levels, i.e. 0-2 levels, are up to standard. Grade 0 means no peeling in the test; grade 1 means peeling, with a peeling area less than 5%; grade 2 means a peeling area greater than 5% but not greater than 15%; and grade 3 means a peeling area greater than 15% but not greater than 35%.

[0150] The test results of Examples 1-3 in Table 3 are all grade 3, which indicates that the interaction of EVA hot melt adhesive, ink layer, and ABS plastic is not strong; and the adhesion grade of Examples 4-6 increases after adding methyl vinyl silicone polymer in the interlayer, which can be because the organic silicon chain and the medium vinyl species of the methyl vinyl silicone polymer are prone to phase separation and significantly transfer to the surface of the ink layer, enriching the uniform silicone layer and permeating the ink layer to enhance the interaction of EVA hot melt adhesive, ink layer, and ABS plastic, thereby improving the adhesion. The adhesion grade of Example 6 with added hexagonal boron nitride in the EVA hot melt adhesive does not change compared with Example 7; however, the adhesion grade of Example 8 with added modified hexagonal boron nitride is 0. This can be because the addition of hexagonal boron nitride to the EVA hot melt adhesive increases the axial stress of the hot melt adhesive and improves the mechanical strength of the hot melt adhesive; the permeated methyl vinyl silicone polymer can interact with the hexagonal boron nitride to improve the adhesion; and the force between the small particle size hexagonal boron nitride and the methyl vinyl silicone polymer is stronger in the more uniformly distributed hot melt adhesive, further improving the adhesion of the transfer film.

[0151] Test Example 3

[0152] The melt index of the hot melt adhesive of the transfer film was tested according to the test method in GB / T 3682-2000 Test Method for Determining the Melt Mass Flow Rate and Melt Volume Flow Rate of Thermoplastics for the mixed glue of step S3 in Examples 8 and 9.

[0153] Table 4 Melt Index

[0154] As can be seen from Table 4, the addition of introduced rosin acid and birch extract can effectively improve the melt index of the EVA sol, i.e., the flowability of the EVA hot melt adhesive is significantly improved, which helps to improve the wetting performance and bonding capacity of the EVA hot melt adhesive. The added birch extract in the present application has good compatibility with the EVA hot melt adhesive, while not affecting the internal crystallization of the EVA hot melt adhesive.

Claims

1. A pre-coated composite film transfer process characterized by, It comprises the following steps: S1: coating of the release layer: the release layer solution is coated on the surface of the BOPP base film by an anilox roller, and dried by segmented heating to form a release layer; S2: coating of the ink layer: the dyeing solution is coated on the release layer obtained in step S1 by an anilox roller, and dried by segmented heating to form an ink layer; S3: coating of the adhesive layer: after the EVA hot melt adhesive is melted, hexagonal boron nitride, rosin acid, and birch extract are added, mixed at 100-200 r / min for 5-10 min, and then coated on the ink layer obtained in step S2 by a heated anilox roller; the mass of the hexagonal boron nitride is 0.5-1% of the hot melt adhesive; the mass of the rosin acid is 1-3% of the hot melt adhesive; and the mass of the birch extract is 10-30% of the hot melt adhesive; S4: the film coated with the hot melt adhesive obtained in step S3 is passed through a cooling anilox roller, solidified by a cold air box, cut, and wound to obtain a pre-coated composite film; S5: the pre-coated composite film obtained in step S4 is hot-pressed on the surface of the packaging material; In the release layer solution of step S1, the mass ratio of each substance is 1-10% protective agent, 10-15% cellulose acetate, 0.05-0.2% leveling agent, and the rest is organic solvent; The leveling agent is a polyether siloxane copolymer leveling agent; The organic solvent is one or a combination of two or more of acetone, butanone, 3-pentanone, cyclohexanone, and toluene; The protective agent in the release layer solution is a methyl vinyl siloxane polymer; The preparation method of the methyl vinyl siloxane polymer is as follows: at a temperature of 60-80℃, octamethylcyclotetrasiloxane, tetraethenyltetramethylcyclotetrasiloxane, and hexamethyldisiloxane are mixed and stirred at a rotational speed of 200-500 r / min for 10-30 min, a catalyst is added in an amount of 1-2% of the total mass of the mixed siloxane, and then reacted at 60-80℃ for 5-10 h; naturally cooled to 20-30℃, and then sodium carbonate is added to adjust the pH to 7.0-8.0; dried at 70-90℃ for 5-10 h to obtain the methyl vinyl siloxane polymer; The catalyst is a combination of triflic acid and phosphoric acid, and the mass ratio of triflic acid to phosphoric acid is (3-5):1; The hexagonal boron nitride is modified to obtain modified hexagonal boron nitride; The preparation method of the modified hexagonal boron nitride is as follows: 1 part by weight of hexagonal boron nitride and 15-20 parts by weight of urea are ball milled at a rotational speed of 500-1000 r / min for 5-10 h; after ball milling, the powder is placed in water and stirred at a rotational speed of 300-500 r / min for 5-10 min to dissolve the urea, then centrifuged at 8000-10000 r / min, washed with ethanol and water three times each, and the insoluble material is dried at 80-100℃ for 5-10 h to obtain the modified hexagonal boron nitride.

2. A pre-coated composite film transfer process as claimed in claim 1, wherein, In the ink layer solution of step S2, the mass ratio of each substance is 10-20% water-based dye, 20-30% water-based polyurethane resin, 0.2-0.5% defoaming agent, 0.2-0.5% antistatic agent, 0.2-0.5% leveling agent, and the rest is cyclohexanone. The defoaming agent is a silicone defoaming agent. The antistatic agent is one, a combination of two or more of a sulfuric acid derivative type, a phosphoric acid derivative type, an amine type, a quaternary ammonium salt type, an imidazole type, and an oxirane derivative type antistatic agent. The leveling agent is a fluorocarbon-modified polyacrylate type leveling agent.

3. A pre-coated composite film transfer process as claimed in claim 1, wherein, The EVA hot melt adhesive in step S3 has a melting temperature of 130-150 DEG C.

4. A pre-coated composite film transfer process as claimed in claim 1, wherein: The screen roller, the heated screen roller, and the cooled screen roller in steps S1-S4 each independently have a mesh of 100-250 mesh.

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