阅读说明：本技术 一种数码打印水转印膜及其制备方法 (Digital printing water transfer printing film and preparation method thereof ) 是由 钱婧 于 2020-12-19 设计创作，主要内容包括：本发明提供了一种数码打印水转印膜及其制备方法,涉及水转印膜技术领域。本发明数码打印水转印膜,以离型膜层作为基底进行负载,通过以PBT树脂为主成分与其他助剂在自由基引发剂过氧化苯甲酰的作用下发生聚合反应,耐热PVA膜层提高了水转印膜的平整度和耐热性,热压形成的光油层更加平整,避免油墨层打印时的无序扩散；该数码打印水转印膜能够展现良好平整的图案,而且耐热性、机械强度良好,保存寿命长。制备方法通过涂覆热压工艺得到层级结构,控制含湿量的同时确保每层结构的厚度和平整度,不仅可以确保良好的打印精度,而且能耗低、污染小,后续水转印操作稳定可控。(The invention provides a digital printing water transfer printing film and a preparation method thereof, relating to the technical field of water transfer printing films. According to the digital printing water transfer film, the release film layer is used as a substrate for carrying out loading, and the PBT resin is used as a main component to perform a polymerization reaction with other additives under the action of the free radical initiator benzoyl peroxide, so that the flatness and heat resistance of the water transfer film are improved by the heat-resistant PVA film layer, the gloss oil layer formed by hot pressing is smoother, and disordered diffusion of the ink layer during printing is avoided; the digital printing water transfer printing film can show good and smooth patterns, and is good in heat resistance and mechanical strength and long in storage life. The preparation method obtains the hierarchical structure through the coating hot pressing process, controls the moisture content and simultaneously ensures the thickness and the flatness of each layer of structure, thereby not only ensuring good printing precision, but also having low energy consumption and little pollution, and the subsequent water transfer printing operation is stable and controllable.)

1. A digital printing water transfer printing film is characterized by comprising a release film layer, an anti-stretching resin film layer, a heat-resistant PVA film layer, a gloss oil layer and an ink layer which are sequentially arranged from inside to outside;

the stretch-resistant resin film layer is prepared from the following components in parts by weight: 35-48 parts of PBT resin, 12-16 parts of hydroxypropyl methacrylate, 0.8-2 parts of methacrylic acid, 0.6-1.2 parts of isobornyl methacrylate, 0.5-1 part of glycidyl methacrylate, 0.1-0.3 part of benzoyl peroxide and 200 parts of ethyl acetate.

2. The digital printing water transfer film according to claim 1, wherein the tensile modulus of the PBT resin is 1200MPa, and the yield stress is 32 MPa.

3. The digital printing water transfer film according to claim 1, wherein the heat-resistant PVA film layer is formed by coating and drying a heat-resistant PVA solution, and the preparation method of the heat-resistant PVA solution is as follows: adding 45-60 parts of water into a reaction kettle according to parts by weight, sequentially adding 2-5 parts of cyclodextrin, 0.5-3 parts of polyoxyethylene fatty alcohol ether and 0.3-2 parts of glycerol, heating to 96-100 ℃, adding 18-30 parts of PVA resin, stirring until the PVA resin is completely dissolved, adding 3-6 parts of nano silicon dioxide powder and 0.05-0.2 part of polydimethylsiloxane, stirring for 20-30min, and standing at 85-90 ℃ for defoaming.

4. The digital printing water transfer film according to claim 1, wherein the viscosity of the PVA resin is 22 mPa-s, the volatile content is less than 9%, and the ash content is less than 1%.

5. The digital printing water transfer film according to claim 1, wherein the varnish layer is prepared by mixing the following components in parts by weight: 35-45 parts of thermoplastic polyurethane resin, 30-40 parts of vinyl chloride-vinyl acetate resin, 75-90 parts of ethyl acetate and 15-25 parts of isopropanol.

6. The method for preparing the digital printing water transfer film according to any one of claims 1 to 5, comprising the steps of:

s1, preparing a stretch-resistant resin film layer liquid: adding 70-80% of ethyl acetate into a reaction kettle, sequentially adding PBT resin, hydroxypropyl methacrylate, isobornyl methacrylate, glycidyl methacrylate and 70-80% of benzoyl peroxide, heating to 90-100 ℃, stirring for 2-3 hours, adding the rest of ethyl acetate, methacrylic acid and the rest of benzoyl peroxide, heating to 115-125 ℃, carrying out heat preservation reaction for 1-2 hours, and standing to obtain an anti-stretching resin film layer liquid;

s2, preparation of gloss oil layer liquid: mixing and stirring the thermoplastic polyurethane resin, 60-70% of ethyl acetate and isopropanol uniformly at 35-45 ℃ to obtain a thermoplastic polyurethane resin solution; mixing and stirring the vinyl chloride-vinyl acetate copolymer and 30-40% ethyl acetate uniformly at 30-40 ℃ to obtain vinyl chloride-vinyl acetate copolymer solution; uniformly mixing a thermoplastic polyurethane resin solution and a vinyl chloride-vinyl acetate resin solution to obtain a gloss oil layer solution;

s3, coating and hot pressing: coating a stretch-resistant resin film layer liquid on one side surface of a release film layer, performing hot press molding to obtain a stretch-resistant resin film layer, coating a layer of heat-resistant PVA solution on the surface of the stretch-resistant resin film layer, and performing hot press to obtain a heat-resistant PVA film layer and a gloss oil layer;

s4, ink-jet printing: printing the image to be printed on the surface of the gloss oil layer by digital ink-jet printing to obtain the ink layer.

7. The method for preparing a digital printing water transfer film according to claim 6, wherein the moisture content is controlled to be 5-8% during the step S3 of hot press forming, the thickness of the stretch-resistant resin film layer is 15-25 μm, the thickness of the heat-resistant PVA film layer is 10-20 μm, and the thickness of the gloss oil layer is 5-12 μm.

8. The method for preparing a digital printing water transfer film according to claim 6, wherein the thickness of the ink layer in step S4 is 10-20 μm.

Technical Field

The invention relates to the technical field of water transfer printing films, in particular to a digital printing water transfer printing film and a preparation method thereof.

Background

The water transfer printing technology is widely used for printing non-planar objects, such as automobile steering wheels, welcome pedals, automobile interior parts, baby carriages, toys, artwork ornaments and the like. The conventional water transfer printing process first prepares a polyvinyl alcohol (PVA) water-soluble film, then prints a pattern on the PVA film by gravure printing, and then performs water transfer printing. Because the PVA film is very soft and cannot be directly subjected to digital ink-jet printing, intaglio printing or silk-screen printing is required, and an intaglio plate or a screen line plate is required to be manufactured in the printing process; and the PVA film has high tensile strength, and the PVA film is easy to deform during printing.

The invention patent of publication No. CN111391531A discloses a preparation method of a digital ink-jet printing water transfer film, which gets rid of the complex processes of plate making, printing and the like required by the traditional water transfer printing, so that a PVA film can be suitable for ink-jet printing. However, researches show that the heat resistance and the mechanical strength of the product of the water transfer printing film before water transfer printing need to be improved, the storage life is not prolonged, and the preparation process can not meet the requirement of simple and controllable process.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a digital printing water transfer printing film and a preparation method thereof.

The invention solves the technical problems through the following technical means:

the invention provides a digital printing water transfer printing film, which comprises a release film layer, an anti-stretching resin film layer, a heat-resistant PVA film layer, a gloss oil layer and an ink layer which are sequentially arranged from inside to outside;

the stretch-resistant resin film layer is prepared from the following components in parts by weight: 35-48 parts of PBT resin, 12-16 parts of hydroxypropyl methacrylate, 0.8-2 parts of methacrylic acid, 0.6-1.2 parts of isobornyl methacrylate, 0.5-1 part of glycidyl methacrylate, 0.1-0.3 part of benzoyl peroxide and 200 parts of ethyl acetate.

The invention relates to a digital printing water transfer printing film, which comprises a release film layer, a stretch-proof resin film layer, a heat-resistant PVA film layer, a gloss oil layer and an ink layer from inside to outside, wherein the release film layer is used as a substrate for loading, and a PBT resin is used as a main component to perform a polymerization reaction with other additives under the action of a free radical initiator benzoyl peroxide, so that the mechanical strength, the casting flatness and the peeling property of the stretch-proof resin film layer are greatly improved by the obtained macromolecular polymer structure, the flatness and the heat resistance of the water transfer printing film are improved by the heat-resistant PVA film layer, the gloss oil layer formed by hot pressing is smoother, and disordered diffusion during printing of the ink layer is avoided.

Further, the tensile modulus of the PBT resin is 1200MPa, and the yield stress is 32 MPa.

Further, the heat-resistant PVA film layer is formed by coating and drying a heat-resistant PVA solution, and the preparation method of the heat-resistant PVA solution comprises the following steps: adding 45-60 parts of water into a reaction kettle according to parts by weight, sequentially adding 2-5 parts of cyclodextrin, 0.5-3 parts of polyoxyethylene fatty alcohol ether and 0.3-2 parts of glycerol, heating to 96-100 ℃, adding 18-30 parts of PVA resin, stirring until the PVA resin is completely dissolved, adding 3-6 parts of nano silicon dioxide powder and 0.05-0.2 part of polydimethylsiloxane, stirring for 20-30min, and standing at 85-90 ℃ for defoaming.

According to the preparation method of the heat-resistant PVA film, the cavity structure of cyclodextrin has good coating property on PVA resin, under the action of the dispersing agent glycerol and the nonionic surfactant polyoxyethylene fatty alcohol ether, the PVA resin powder is coated by the cyclodextrin after being dispersed, the nano silicon dioxide powder is adsorbed at the same time, the heat resistance and the strength of the coating structure are improved, and under the action of the defoaming agent polydimethylsiloxane, bubbles in the cavity structure of the cyclodextrin are adsorbed and removed, so that the uniformly dispersed heat-resistant PVA solution is obtained.

Further, the PVA resin has a viscosity of 22mPa · s, a volatile content of less than 9%, and an ash content of less than 1%.

Further, the gloss oil layer is prepared by mixing the following components in parts by weight: 35-45 parts of thermoplastic polyurethane resin, 30-40 parts of vinyl chloride-vinyl acetate resin, 75-90 parts of ethyl acetate and 15-25 parts of isopropanol.

The invention also provides a preparation method of the digital printing water transfer printing film, which comprises the following steps:

s1, preparing a stretch-resistant resin film layer liquid: adding 70-80% of ethyl acetate into a reaction kettle, sequentially adding PBT resin, hydroxypropyl methacrylate, isobornyl methacrylate, glycidyl methacrylate and 70-80% of benzoyl peroxide, heating to 90-100 ℃, stirring for 2-3 hours, adding the rest of ethyl acetate, methacrylic acid and the rest of benzoyl peroxide, heating to 115-125 ℃, carrying out heat preservation reaction for 1-2 hours, and standing to obtain an anti-stretching resin film layer liquid;

s2, preparation of gloss oil layer liquid: mixing and stirring the thermoplastic polyurethane resin, 60-70% of ethyl acetate and isopropanol uniformly at 35-45 ℃ to obtain a thermoplastic polyurethane resin solution; mixing and stirring the vinyl chloride-vinyl acetate copolymer and 30-40% ethyl acetate uniformly at 30-40 ℃ to obtain vinyl chloride-vinyl acetate copolymer solution; uniformly mixing a thermoplastic polyurethane resin solution and a vinyl chloride-vinyl acetate resin solution to obtain a gloss oil layer solution;

s3, coating and hot pressing: coating a stretch-resistant resin film layer liquid on one side surface of a release film layer, performing hot press molding to obtain a stretch-resistant resin film layer, coating a layer of heat-resistant PVA solution on the surface of the stretch-resistant resin film layer, and performing hot press to obtain a heat-resistant PVA film layer and a gloss oil layer;

s4, ink-jet printing: printing the image to be printed on the surface of the gloss oil layer by digital ink-jet printing to obtain the ink layer.

According to the preparation method of the digital printing water transfer film, the hierarchical structure is obtained through a simple coating hot pressing process, the thickness and the flatness of each layer of structure are ensured while the moisture content is controlled, good printing precision can be ensured, the energy consumption is low, the pollution is small, when the preparation method is used, the stretch-resistant resin film layer and the heat-resistant PVA film layer are peeled off, the ink layer is upwards paved in the water tank, the gloss oil layer and the heat-resistant PVA film layer are dissolved into a liquid state, and after a workpiece is placed in the water tank, the ink layer is transferred to the surface of the workpiece to finish water transfer printing.

Further, the moisture content is controlled to be 5-8% during the hot press molding in the step S3, the thickness of the tensile resin film layer is 15-25 μm, the thickness of the heat-resistant PVA film layer is 10-20 μm, and the thickness of the gloss oil layer is 5-12 μm.

Further, the thickness of the ink layer in step S4 is 10 to 20 μm.

The invention has the beneficial effects that:

(1) according to the digital printing water transfer printing film, the release film layer is used as a substrate for carrying out loading, the PBT resin is used as a main component and is subjected to polymerization reaction with other additives under the action of the free radical initiator benzoyl peroxide, so that the mechanical strength, the casting flatness and the stripping property of the stretch-resistant resin film layer are improved, the flatness and the heat resistance of the water transfer printing film are improved by the heat-resistant PVA film layer, the gloss oil layer formed by hot pressing is more flat, and disordered diffusion of the ink layer during printing is avoided; the digital printing water transfer printing film can show good and smooth patterns, and is good in heat resistance and mechanical strength and long in storage life.

(2) According to the preparation method of the digital printing water transfer film, the hierarchical structure is obtained through the coating hot pressing process, the moisture content is controlled, and meanwhile the thickness and the flatness of each layer of structure are ensured, so that the good printing precision can be ensured, the energy consumption is low, the pollution is small, and the subsequent water transfer operation is stable and controllable.

Drawings

FIG. 1 is a schematic structural diagram of a digital printing water transfer film according to the present invention;

fig. 2 is a flow chart of a preparation method of the digital printing water transfer film of the invention.

In the figure: 1. a release film layer; 2. a tensile resin film layer; 3. a heat-resistant PVA film layer; 4. polishing the oil layer; 5. and (4) an ink layer.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It will be understood that when an element is referred to as being "secured to" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present.

Example 1

As shown in fig. 1-2, the digital printing water transfer film of the embodiment includes a release film layer 1, a stretch-resistant resin film layer 2, a heat-resistant PVA film layer 3, a gloss oil layer 4, and an ink layer 5, which are sequentially disposed from inside to outside.

The stretch-resistant resin film layer is prepared from the following components in parts by weight: 43 parts of PBT resin, 15 parts of hydroxypropyl methacrylate, 1.4 parts of methacrylic acid, 0.9 part of isobornyl methacrylate, 0.8 part of glycidyl methacrylate, 0.16 part of benzoyl peroxide and 185 parts of ethyl acetate. The tensile modulus of the PBT resin is 1200MPa, and the yield stress is 32 MPa.

The heat-resistant PVA film layer is formed by coating and drying a heat-resistant PVA solution, and the preparation method of the heat-resistant PVA solution comprises the following steps: adding 53 parts of water, 4 parts of cyclodextrin, 1.8 parts of polyoxyethylene fatty alcohol ether and 0.9 part of glycerol into a reaction kettle in sequence according to the parts by weight, heating to 98 ℃, adding 25 parts of PVA resin, stirring until the PVA resin is completely dissolved, adding 4 parts of nano silicon dioxide powder and 0.12 part of polydimethylsiloxane, stirring for 25min, and standing at 87 ℃ for defoaming. The PVA resin had a viscosity of 22 mPas, a volatile content of less than 9% and an ash content of less than 1%.

The gloss oil layer is prepared by mixing the following components in parts by weight: 40 parts of thermoplastic polyurethane resin, 35 parts of vinyl chloride-vinyl acetate copolymer, 83 parts of ethyl acetate and 23 parts of isopropanol.

The preparation method of the digital printing water transfer printing film comprises the following steps:

s1, preparing a stretch-resistant resin film layer liquid: adding 75% of ethyl acetate into a reaction kettle, sequentially adding PBT resin, hydroxypropyl methacrylate, isobornyl methacrylate, glycidyl methacrylate and 75% of benzoyl peroxide, heating to 96 ℃, stirring for 2.5 hours, adding the rest of ethyl acetate, methacrylic acid and the rest of benzoyl peroxide, heating to 123 ℃, keeping the temperature, reacting for 1.6 hours, and standing to obtain an anti-stretching resin film layer liquid;

s2, preparation of gloss oil layer liquid: mixing and stirring the thermoplastic polyurethane resin, 65% of ethyl acetate and isopropanol uniformly at 42 ℃ to obtain a thermoplastic polyurethane resin solution; mixing and stirring the vinyl chloride-vinyl acetate copolymer and 35% ethyl acetate uniformly at 36 ℃ to obtain vinyl chloride-vinyl acetate copolymer solution; uniformly mixing a thermoplastic polyurethane resin solution and a vinyl chloride-vinyl acetate resin solution to obtain a gloss oil layer solution;

s3, coating and hot pressing: coating a stretch-resistant resin film layer liquid on one side surface of a release film layer, performing hot press molding to obtain a stretch-resistant resin film layer, coating a layer of heat-resistant PVA solution on the surface of the stretch-resistant resin film layer, and performing hot press to obtain a heat-resistant PVA film layer and a gloss oil layer; the moisture content is controlled to be 5-8% during hot-press molding, the thickness of the tensile resin film layer is 20 microns, the thickness of the heat-resistant PVA film layer is 16 microns, and the thickness of the gloss oil layer is 8 microns.

S4, ink-jet printing: printing an image to be printed on the surface of the gloss oil layer by digital ink-jet printing to obtain an ink layer, wherein the thickness of the ink layer is 16 mu m.

Example 2

As shown in fig. 1-2, the digital printing water transfer film of the embodiment includes a release film layer 1, a stretch-resistant resin film layer 2, a heat-resistant PVA film layer 3, a gloss oil layer 4, and an ink layer 5, which are sequentially disposed from inside to outside.

The stretch-resistant resin film layer is prepared from the following components in parts by weight: 46 parts of PBT resin, 14 parts of hydroxypropyl methacrylate, 1.8 parts of methacrylic acid, 1 part of isobornyl methacrylate, 0.9 part of glycidyl methacrylate, 0.25 part of benzoyl peroxide and 190 parts of ethyl acetate. The tensile modulus of the PBT resin is 1200MPa, and the yield stress is 32 MPa.

The heat-resistant PVA film layer is formed by coating and drying a heat-resistant PVA solution, and the preparation method of the heat-resistant PVA solution comprises the following steps: adding 55 parts of water, 4.6 parts of cyclodextrin, 2.6 parts of polyoxyethylene fatty alcohol ether and 1.4 parts of glycerol into a reaction kettle in sequence according to the parts by weight, heating to 99 ℃, adding 25 parts of PVA resin, stirring until the PVA resin is completely dissolved, adding 5 parts of nano silicon dioxide powder and 0.15 part of polydimethylsiloxane, stirring for 28min, and standing at 87 ℃ for defoaming. The PVA resin had a viscosity of 22 mPas, a volatile content of less than 9% and an ash content of less than 1%.

The gloss oil layer is prepared by mixing the following components in parts by weight: 43 parts of thermoplastic polyurethane resin, 38 parts of vinyl chloride-vinyl acetate copolymer, 86 parts of ethyl acetate and 22 parts of isopropanol.

The preparation method of the digital printing water transfer printing film comprises the following steps:

s1, preparing a stretch-resistant resin film layer liquid: adding 72% of ethyl acetate into a reaction kettle, sequentially adding PBT resin, hydroxypropyl methacrylate, isobornyl methacrylate, glycidyl methacrylate and 76% of benzoyl peroxide, heating to 98 ℃, stirring for 2.8 hours, adding the rest of ethyl acetate, methacrylic acid and the rest of benzoyl peroxide, heating to 123 ℃, keeping the temperature, reacting for 1.6 hours, and standing to obtain an anti-stretching resin film layer liquid;

s2, preparation of gloss oil layer liquid: mixing and stirring the thermoplastic polyurethane resin, 66% ethyl acetate and isopropanol uniformly at 43 ℃ to obtain a thermoplastic polyurethane resin solution; mixing and stirring the vinyl chloride-vinyl acetate copolymer and 34% ethyl acetate uniformly at 38 ℃ to obtain vinyl chloride-vinyl acetate copolymer solution; uniformly mixing a thermoplastic polyurethane resin solution and a vinyl chloride-vinyl acetate resin solution to obtain a gloss oil layer solution;

s3, coating and hot pressing: coating a stretch-resistant resin film layer liquid on one side surface of a release film layer, performing hot press molding to obtain a stretch-resistant resin film layer, coating a layer of heat-resistant PVA solution on the surface of the stretch-resistant resin film layer, and performing hot press to obtain a heat-resistant PVA film layer and a gloss oil layer; the moisture content is controlled to be 5-8% during hot-press molding, the thickness of the tensile resin film layer is 22 mu m, the thickness of the heat-resistant PVA film layer is 18 mu m, and the thickness of the gloss oil layer is 11 mu m.

S4, ink-jet printing: printing an image to be printed on the surface of the gloss oil layer by digital ink-jet printing to obtain an ink layer, wherein the thickness of the ink layer is 16 mu m.

Example 3

As shown in fig. 1-2, the digital printing water transfer film of the embodiment includes a release film layer 1, a stretch-resistant resin film layer 2, a heat-resistant PVA film layer 3, a gloss oil layer 4, and an ink layer 5, which are sequentially disposed from inside to outside.

The stretch-resistant resin film layer is prepared from the following components in parts by weight: 46 parts of PBT resin, 15 parts of hydroxypropyl methacrylate, 1.6 parts of methacrylic acid, 0.7 part of isobornyl methacrylate, 0.8 part of glycidyl methacrylate, 0.25 part of benzoyl peroxide and 190 parts of ethyl acetate. The tensile modulus of the PBT resin is 1200MPa, and the yield stress is 32 MPa.

The heat-resistant PVA film layer is formed by coating and drying a heat-resistant PVA solution, and the preparation method of the heat-resistant PVA solution comprises the following steps: adding 58 parts of water, 4.5 parts of cyclodextrin, 2.3 parts of polyoxyethylene fatty alcohol ether and 1.5 parts of glycerol into a reaction kettle in sequence according to the parts by weight, heating to 100 ℃, adding 27 parts of PVA resin, stirring until the PVA resin is completely dissolved, adding 5.2 parts of nano silicon dioxide powder and 0.16 part of polydimethylsiloxane, stirring for 28min, and standing at 89 ℃ for defoaming. The PVA resin had a viscosity of 22 mPas, a volatile content of less than 9% and an ash content of less than 1%.

The gloss oil layer is prepared by mixing the following components in parts by weight: 43 parts of thermoplastic polyurethane resin, 38 parts of vinyl chloride-vinyl acetate copolymer, 86 parts of ethyl acetate and 24 parts of isopropanol.

The preparation method of the digital printing water transfer printing film comprises the following steps:

s1, preparing a stretch-resistant resin film layer liquid: adding 78% of ethyl acetate into a reaction kettle, sequentially adding PBT resin, hydroxypropyl methacrylate, isobornyl methacrylate, glycidyl methacrylate and 73% of benzoyl peroxide, heating to 97 ℃, stirring for 2.3 hours, adding the rest of ethyl acetate, methacrylic acid and the rest of benzoyl peroxide, heating to 122 ℃, carrying out heat preservation reaction for 1.8 hours, and standing to obtain an anti-stretching resin film layer liquid;

s2, preparation of gloss oil layer liquid: mixing and stirring the thermoplastic polyurethane resin, 60-70% of ethyl acetate and isopropanol uniformly at 35-45 ℃ to obtain a thermoplastic polyurethane resin solution; mixing and stirring the vinyl chloride-vinyl acetate copolymer and 30-40% ethyl acetate uniformly at 30-40 ℃ to obtain vinyl chloride-vinyl acetate copolymer solution; uniformly mixing a thermoplastic polyurethane resin solution and a vinyl chloride-vinyl acetate resin solution to obtain a gloss oil layer solution;

s3, coating and hot pressing: coating a stretch-resistant resin film layer liquid on one side surface of a release film layer, performing hot press molding to obtain a stretch-resistant resin film layer, coating a layer of heat-resistant PVA solution on the surface of the stretch-resistant resin film layer, and performing hot press to obtain a heat-resistant PVA film layer and a gloss oil layer; the moisture content is controlled to be 5-8% during hot-press molding, the thickness of the tensile resin film layer is 23 μm, the thickness of the heat-resistant PVA film layer is 14 μm, and the thickness of the gloss oil layer is 10 μm.

S4, ink-jet printing: printing an image to be printed on the surface of the gloss oil layer by digital ink-jet printing to obtain an ink layer, wherein the thickness of the ink layer is 15 microns.

Comparative example 1

The comparative example is different from example 1 in that the stretch-resistant resin film layer liquid is formed by mixing PBT resin and ethyl acetate.

Comparative example 2

This comparative example is different from example 1 in that the nano-silica powder is not added to the heat-resistant PVA solution.

Performance testing

The digital printing water transfer films prepared in the examples 1-3 and the comparative examples 1-2 are tested for heat shrinkage and tensile strength according to the industrial standard BB/T0551-2017, and the specific results are shown in the following table:

item	Thermal shrinkage/%	Tensile strength/MPa
			Example 1	2.8	158
Example 2	3.2	155
			Example 3	3.6	152
Comparative example 1	5.3	128
			Comparative example 2	5.8	134

As can be seen from the table above, the digital printing water transfer film prepared by the embodiment of the invention has the advantages of small thermal shrinkage and high tensile strength, which shows that the heat resistance and the tensile resistance are superior to those of the comparative example, and the storage life is prolonged.

It is noted that, in this document, relational terms such as first and second, and the like, if any, are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

The above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.