Thermal transfer paper and preparation method thereof

Abstract

The invention provides a thermal transfer paper and a preparation method thereof, comprising a base paper, a TPU layer, an intermediate layer, an ink absorbing layer and an ink-fixing layer which are arranged in sequence from bottom to top; pure acrylate is arranged in the intermediate layer to strengthen the bonding force between the ink absorbing layer and the TPU layer; the ink absorbing coating is arranged as a three-layer structure including the intermediate layer, the ink absorbing layer and the ink-fixing layer, the pure acrylate in the intermediate layer strengthens the bonding force between the ink absorbing layer and the TPU layer, the TPU powder in the ink-fixing layer is dispersed in an aqueous hot melt adhesive to form a microporous structure, the ink is allowed to penetrate into the ink absorbing layer during inkjet printing, melted to form a film during hot pressing, the pores are filled and the water resistance of the coating is improved, the polyurethane resin and the ink absorbing filler in the ink absorbing layer absorb the solvent in the dye ink, and provide excellent printing effect and drying speed, the thermal transfer paper as a whole has the characteristics of clear pattern, high color saturation, fast drying speed, strong water washing resistance and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of thermal transfer, and in particular relates to thermal transfer paper and a preparation method thereof. Background Art

[0002] In order to actively respond to environmental protection and reduce pollution, the thermal transfer field has switched from using oil-based transfer inks to using water-based transfer inks. However, water-based inks will blur when exposed to water, and the printed dots will spread.

[0003] Thermal transfer paper takes coating technology as its core technology, which directly determines the quality of thermal transfer paper. The research and development level of coating technology indicates the research level of thermal transfer paper. In the existing technology, the production process and formula types of ink-absorbing coatings in thermal transfer paper are mainly based on swelling type. The swelling type is a resin-based ink-absorbing layer, which uses polymers that can absorb water and swell. After receiving ink droplets, the surface of this type of coating expands slightly to form a network to absorb the ink droplets; however, the water resistance of this medium is poor, and after the water resistance is improved by cross-linking agent modification, the ink absorption is reduced again, that is, the ink absorption and water resistance are contradictory. This type of inkjet printing paper can no longer meet the high-quality printing requirements, and high-quality gap-type printing paper has become the direction of market development. Summary of the invention

[0004] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a thermal transfer paper with clear printed patterns, high color saturation, fast ink drying speed and strong water washing resistance.

[0005] The present invention provides a thermal transfer paper, comprising a base paper, a TPU layer, an intermediate layer, an ink absorbing layer and an ink fixing layer arranged in sequence from bottom to top;

[0006] Pure acrylic ester is provided in the middle layer to enhance the bonding effect between the ink-absorbing layer and the TPU layer;

[0007] The ink-absorbing layer comprises the following raw materials expressed in parts by weight: 40-50 parts of non-ionic polyurethane emulsion, 10-20 parts of hydrophobic matting powder, 1-7 parts of cationic color fixing agent, 10-20 parts of deionized water, 1-2 parts of barium sulfate, 1-3 parts of non-water-soluble plasticizer, 1-5 parts of non-water-soluble antioxidant, 1-2 parts of defoaming agent, 1-2 parts of dispersant, 1-2 parts of wetting agent, 1-2 parts of surfactant, 1-2 parts of leveling agent, 1-2 parts of coupling agent, and 1-2 parts of water repellent;

[0008] The solid ink layer includes the following raw materials expressed in parts by weight: 40-50 parts of water-based hot melt adhesive, 15-25 parts of TPU powder, 10-20 parts of anhydrous ethanol, 0.1-0.4 parts of thickener, 1-2 parts of dispersant, 1-2 parts of wetting agent, 1-2 parts of surfactant, 1-2 parts of leveling agent, and 1-2 parts of defoaming agent.

[0009] Optionally, the TPU powder is disposed in the aqueous hot melt adhesive emulsion in a uniformly dispersed manner, and the TPU powder and the aqueous hot melt adhesive emulsion form a microporous structure with each other.

[0010] Optionally, the nonionic polyurethane emulsion is set to be any one of cationic polyurethane emulsion, anionic polyurethane emulsion or nonionic polyurethane emulsion.

[0011] Optionally, the cationic color fixing agent is any one of polyethylene amine, polyethylene imine, polydimethyldiallylammonium chloride, a high polymerization degree polyamine type cationic color fixing agent or polyvinylbenzyltrimethylammonium chloride.

[0012] Optionally, the water repellent is any one of ammonium zirconium carbonate, polyamide polyurea resin, urea-formaldehyde resin, melamine formaldehyde resin, modified glyoxal or formaldehyde.

[0013] Optionally, the surfactant is set to be any one of oleic acid diethanolamide, hexadecyltrimethylammonium chloride, dodecyldimethylbetaine or sodium dodecyldiphenyl oxide disulfonate.

[0014] The present invention also provides a method for preparing the thermal transfer paper as described above, which specifically comprises the following steps:

[0015] Step 1: Laminate the base paper and TPU film;

[0016] Step 2: Evenly coat the pure acrylate in the middle layer on the TPU layer through a coater with a thickness of 10um. The drying temperature of the coater is 80°C and the speed is 2m / min.

[0017] Step 3: Use a coating machine to evenly coat the prepared ink-absorbing layer coating on the middle layer with a thickness of 40-50um. The drying temperature of the coating machine is 80°C and the speed is 2m / min.

[0018] Step 4: Use a coating machine to evenly coat the prepared ink-fixing layer coating on the ink-absorbing layer with a thickness of 60-80um. The drying temperature of the coating machine is 80°C and the speed is 2m / min.

[0019] Optionally, the preparation process of the ink-absorbing layer coating is as follows:

[0020] Step 1, weigh the raw materials by weight;

[0021] Step 2: Pour the dispersant, wetting agent, leveling agent, surfactant, defoamer and deionized water weighed in step 1 into a reaction kettle at room temperature, and stir at a speed of 300-500 r / min for 2-3 minutes;

[0022] Step 3, pour the weighed polyurethane emulsion into the reaction kettle and stir at 500-800 r / min for 5-10 minutes;

[0023] Step 4: Pour the weighed ink-absorbing filler and coupling agent into the reaction kettle and stir at 1200-1600 r / min for 20-30 minutes;

[0024] Step 5, pour the weighed precipitated barium sulfate, cationic color fixing agent, water-insoluble plasticizer, and water-insoluble antioxidant into the reaction kettle, and stir at 500-800 r / min for 5-10 minutes;

[0025] Step 6: Slowly pour the water repellent weighed in step 1 into the reaction kettle and stir at 300-500 r / min for 3-5 minutes.

[0026] Optionally, the preparation process of the ink-fixing layer coating is specifically as follows:

[0027] Step 1), weigh the raw materials by weight;

[0028] Step 2), pour the defoamer, dispersant, wetting agent, leveling agent, surfactant, deionized water and water-based hot melt adhesive weighed in step 1) into the reaction kettle at room temperature, and stir at 300-500 r / min for 2-3 minutes;

[0029] Step 3), pour the weighed thickener into the weighed anhydrous ethanol, stir at 500-800r / min for 2-3 minutes to fully dissolve it;

[0030] Step 4), pour the dissolved anhydrous ethanol-thickener mixture into the reactor and stir at 1200-1600 r / min for 5-10 minutes;

[0031] Step 5) Pour the weighed TPU powder into the reactor and stir at 1500-2000 r / min for 20-30 minutes.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] The thermal transfer paper provided by the present invention has an ink-absorbing coating layer as a three-layer structure including an intermediate layer, an ink-absorbing layer and an ink-fixing layer. The pure acrylic ester in the intermediate layer strengthens the adhesion between the ink-absorbing layer and the TPU layer. The TPU powder in the ink-fixing layer is dispersed in the aqueous hot melt adhesive to form a microporous structure. During inkjet printing, the ink is allowed to penetrate into the ink-absorbing layer and melt into a film during hot pressing, thereby filling the pores and improving the water resistance of the coating. The polyurethane resin and ink-absorbing filler in the ink-absorbing layer absorb the solvent in the dye ink, thereby providing excellent printing effect and drying speed. The thermal transfer paper as a whole has the characteristics of clear pattern, high color saturation, fast drying speed, strong water washing resistance, etc.

[0034] In addition to the objects, features and advantages described above, the present invention has other objects, features and advantages. DETAILED DESCRIPTION

[0035] The present invention is further described in detail below in conjunction with the examples. It should be understood that the preparation methods described in the examples of the present invention are only used to illustrate the present invention, rather than to limit the present invention, and simple improvements to the preparation methods of the present invention under the premise of the concept of the present invention belong to the scope of protection claimed in the present invention.

[0036] Embodiment 1:

[0037] The present invention provides a thermal transfer paper, comprising a base paper, a TPU layer, an intermediate layer, an ink absorbing layer and an ink fixing layer arranged in sequence from bottom to top;

[0038] The base paper is used to protect the TPU layer from dust or scratches before use, thereby preventing it from losing adhesion;

[0039] The intermediate layer is provided with pure acrylate, which mainly plays the role of strengthening the bonding force between the ink-absorbing layer and the TPU layer;

[0040] The ink-fixing layer and the ink-absorbing layer are connected to each other.

[0041] As a further embodiment of the present invention, the ink-absorbing layer includes the following raw materials expressed in parts by weight: 40 parts of non-ionic polyurethane emulsion, 10 parts of hydrophobic matting powder, 1 part of cationic color fixing agent, 10-20 parts of deionized water, 1 part of barium sulfate, 1 part of non-water-soluble plasticizer, 1 part of non-water-soluble antioxidant, 1 part of defoamer, 1 part of dispersant, 1 part of wetting agent, 1 part of surfactant, 1 part of leveling agent, 1 part of coupling agent, and 1 part of water repellent. The waterproof functional layer includes the following components in parts by weight: 40 parts of water-based hot melt adhesive, 15 parts of TPU powder, 10 parts of anhydrous ethanol, 0.1 parts of thickener, 1 part of defoamer, 1 part of dispersant, 1 part of wetting agent, 1 part of surfactant, and 1 part of leveling agent.

[0042] Optionally, the nonionic polyurethane emulsion is preferably set to be any one of a cationic polyurethane emulsion, an anionic polyurethane emulsion or a nonionic polyurethane emulsion.

[0043] Optionally, the cationic color fixing agent is preferably set to any one of polyvinylamine, polyethyleneimine, polydimethyldiallyl ammonium chloride, a high-polymerization degree polyamine cationic color fixing agent or polyvinylbenzyltrimethylammonium chloride.

[0044] Optionally, the surfactant is preferably set to any one of oleic acid diethanolamide, hexadecyltrimethylammonium chloride, dodecyldimethylbetaine or sodium dodecyldiphenyl oxide disulfonate.

[0045] Optionally, the water repellent is preferably configured as any one of ammonium zirconium carbonate, polyamide polyurea resin, urea-formaldehyde resin, melamine formaldehyde resin, modified glyoxal or formaldehyde.

[0046] As a further embodiment of the present invention, the ink-fixing layer comprises the following raw materials expressed by weight: 40-50 parts of aqueous hot melt adhesive, 15-25 parts of TPU powder, 10-20 parts of anhydrous ethanol, 0.1-0.4 parts of thickener, 1-2 parts of dispersant, 1-2 parts of wetting agent, 1-2 parts of surfactant, 1-2 parts of leveling agent, and 1-2 parts of defoamer. The TPU powder is evenly dispersed in the aqueous hot melt adhesive emulsion to form a microporous structure.

[0047] The present invention also provides a method for preparing thermal transfer paper, comprising the following steps:

[0048] Step 1: Laminate the base paper and TPU film;

[0049] Step 2: Evenly coat the pure acrylate in the middle layer on the TPU layer through a coater with a thickness of 10um. The drying temperature of the coater is 80°C and the speed is 2m / min.

[0050] Step 3: Use a coating machine to evenly coat the prepared ink-absorbing layer coating on the middle layer with a thickness of 40um. The drying temperature of the coating machine is 80°C and the speed is 2m / min.

[0051] Step 4: Use a coating machine to evenly coat the prepared ink-fixing layer coating on the ink-absorbing layer with a thickness of 60um. The drying temperature of the coating machine is 80°C and the speed is 2m / min.

[0052] Furthermore, the preparation process of the ink-absorbing layer coating is as follows:

[0053] Step 1, weigh the raw materials by weight;

[0054] Step 2: Pour the dispersant, wetting agent, leveling agent, surfactant, defoamer and deionized water weighed in step 1 into a reaction kettle at room temperature, and stir at a speed of 300-500 r / min for 2-3 minutes;

[0055] Step 3, pour the weighed polyurethane emulsion into the reaction kettle and stir at 500-800 r / min for 5-10 minutes;

[0056] Step 4: Pour the weighed ink-absorbing filler and coupling agent into the reaction kettle and stir at 1200-1600 r / min for 20-30 minutes;

[0057] Step 5, pour the weighed precipitated barium sulfate, cationic color fixing agent, water-insoluble plasticizer, and water-insoluble antioxidant into the reaction kettle, and stir at 500-800 r / min for 5-10 minutes;

[0058] Step 6: Slowly pour the water repellent weighed in step 1 into the reaction kettle and stir at 300-500 r / min for 3-5 minutes.

[0059] Furthermore, the preparation process of the ink-fixing layer coating is as follows:

[0060] Step 1), weigh the raw materials by weight;

[0061] Step 2), pour the defoamer, dispersant, wetting agent, leveling agent, surfactant, deionized water and water-based hot melt adhesive weighed in step 1) into the reaction kettle at room temperature, and stir at 300-500 r / min for 2-3 minutes;

[0062] Step 3), pour the weighed thickener into the weighed anhydrous ethanol, stir at 500-800r / min for 2-3 minutes to fully dissolve it;

[0063] Step 4), pour the dissolved anhydrous ethanol-thickener mixture into the reactor and stir at 1200-1600 r / min for 5-10 minutes;

[0064] Step 5) Pour the weighed TPU powder into the reactor and stir at 1500-2000 r / min for 20-30 minutes.

[0065] Embodiment 2:

[0066] In addition to the above, the thermal transfer paper provided by the present invention can also be configured with an ink absorbing layer as follows:

[0067] The ink-absorbing layer includes the following raw materials in parts by weight: 50 parts of non-ionic polyurethane emulsion, 20 parts of hydrophobic matting powder, 7 parts of cationic color fixing agent, 20 parts of deionized water, 2 parts of barium sulfate, 3 parts of non-water-soluble plasticizer, 5 parts of non-water-soluble antioxidant, 1 part of defoamer, 2 parts of dispersant, 2 parts of wetting agent, 2 parts of surfactant, 2 parts of leveling agent, 2 parts of coupling agent, and 2 parts of water repellent. The waterproof functional layer includes the following components in parts by weight: 50 parts of water-based hot melt adhesive, 25 parts of TPU powder, 20 parts of anhydrous ethanol, 0.4 parts of thickener, 1 part of defoamer, 2 parts of dispersant, 2 parts of wetting agent, 2 parts of surfactant, and 2 parts of leveling agent.

[0068] Based on the setting of the ink absorbing layer in the thermal transfer paper described in this embodiment, the preparation method of the thermal transfer paper includes the following steps:

[0069] Step 1: Laminate the base paper and TPU film;

[0070] Step 2: Evenly coat the pure acrylate in the middle layer on the TPU layer through a coater with a thickness of 10um. The drying temperature of the coater is 80°C and the speed is 2m / min.

[0071] Step 3: Use a coating machine to evenly coat the prepared ink-absorbing layer coating on the middle layer with a thickness of 50um. The drying temperature of the coating machine is 80°C and the speed is 2m / min.

[0072] Step 4: Use a coating machine to evenly coat the prepared solid ink layer coating on the ink absorbing layer with a thickness of 80um. The drying temperature of the coating machine is 80°C and the speed is 2m / min.

[0073] Embodiment 3:

[0074] In addition to the above, the thermal transfer paper provided by the present invention can also be configured with an ink absorbing layer as follows:

[0075] The ink-absorbing layer includes the following raw materials in parts by weight: 45 parts of non-ionic polyurethane emulsion, 15 parts of hydrophobic matting powder, 4 parts of cationic color fixing agent, 15 parts of deionized water, 2 parts of barium sulfate, 2 parts of non-water-soluble plasticizer, 3 parts of non-water-soluble antioxidant, 1 part of defoamer, 2 parts of dispersant, 2 parts of wetting agent, 2 parts of surfactant, 2 parts of leveling agent, 2 parts of coupling agent, and 2 parts of water repellent. The waterproof functional layer includes the following components in parts by weight: 45 parts of water-based hot melt adhesive, 20 parts of TPU powder, 15 parts of anhydrous ethanol, 0.2 parts of thickener, 1 part of defoamer, 2 parts of dispersant, 2 parts of wetting agent, 2 parts of surfactant, and 2 parts of leveling agent.

[0076] Based on the setting of the ink absorbing layer in the thermal transfer paper described in this embodiment, the preparation method of the thermal transfer paper includes the following steps:

[0077] Step 1: Laminate the base paper and TPU film;

[0078] Step 2: Evenly coat the pure acrylate in the middle layer on the TPU layer through a coater with a thickness of 10um. The drying temperature of the coater is 80°C and the speed is 2m / min.

[0079] Step 3: Use a coating machine to evenly coat the prepared ink-absorbing layer coating on the middle layer with a thickness of 45um. The drying temperature of the coating machine is 80°C and the speed is 2m / min.

[0080] Step 4: Use a coating machine to evenly coat the prepared ink-fixing layer coating on the ink-absorbing layer with a thickness of 70um, a drying temperature of 80°C, and a speed of 2m / min.

[0081] Embodiment 4:

[0082] In addition to the above, the thermal transfer paper provided by the present invention can also be configured with an ink absorbing layer as follows:

[0083] The ink-absorbing layer includes the following raw materials in parts by weight: 35 parts of non-ionic polyurethane emulsion, 8 parts of hydrophobic matting powder, 0.5 parts of cationic color fixing agent, 8 parts of deionized water, 1 part of barium sulfate, 1 part of non-water-soluble plasticizer, 1 part of non-water-soluble antioxidant, 1 part of defoamer, 1 part of dispersant, 1 part of wetting agent, 1 part of surfactant, 1 part of leveling agent, 1 part of coupling agent, and 1 part of water repellent. The waterproof functional layer includes the following components in parts by weight: 30 parts of water-based hot melt adhesive, 10 parts of TPU powder, 6 parts of anhydrous ethanol, 0.1 parts of thickener, 1 part of defoamer, 1 part of dispersant, 1 part of wetting agent, 1 part of surfactant, and 1 part of leveling agent.

[0084] Based on the setting of the ink absorbing layer in the thermal transfer paper described in this embodiment, the preparation method of the thermal transfer paper includes the following steps:

[0085] Step 1: Laminate the base paper and TPU film;

[0086] Step 2: Evenly coat the pure acrylate in the middle layer on the TPU layer through a coater with a thickness of 10um. The drying temperature of the coater is 80°C and the speed is 2m / min.

[0087] Step 3: Use a coating machine to evenly coat the prepared ink-absorbing layer coating on the middle layer with a thickness of 30um. The drying temperature of the coating machine is 80°C and the speed is 2m / min.

[0088] Step 4: Use a coating machine to evenly coat the prepared solid ink layer coating on the ink absorbing layer with a thickness of 50um. The drying temperature of the coating machine is 80°C and the speed is 2m / min.

[0089] Embodiment 5:

[0090] In addition to the above, the thermal transfer paper provided by the present invention can also be configured with an ink absorbing layer as follows:

[0091] The ink-absorbing layer includes the following raw materials in parts by weight: 55 parts of non-ionic polyurethane emulsion, 30 parts of hydrophobic matting powder, 10 parts of cationic color fixing agent, 25 parts of deionized water, 2 parts of barium sulfate, 2 parts of non-water-soluble plasticizer, 5 parts of non-water-soluble antioxidant, 2 parts of defoamer, 2 parts of dispersant, 2 parts of wetting agent, 2 parts of surfactant, 2 parts of leveling agent, 2 parts of coupling agent, and 2 parts of water repellent. The waterproof functional layer includes the following components in parts by weight: 60 parts of water-based hot melt adhesive, 30 parts of TPU powder, 25 parts of anhydrous ethanol, 0.4 parts of thickener, 2 parts of defoamer, 2 parts of dispersant, 2 parts of wetting agent, 2 parts of surfactant, and 2 parts of leveling agent.

[0092] Based on the setting of the ink absorbing layer in the thermal transfer paper described in this embodiment, the preparation method of the thermal transfer paper includes the following steps:

[0093] Step 1: Laminate the base paper and TPU film;

[0094] Step 2: Evenly coat the pure acrylate in the middle layer on the TPU layer through a coater with a thickness of 10um. The drying temperature of the coater is 80°C and the speed is 2m / min.

[0095] Step 3: Use a coating machine to evenly coat the prepared ink-absorbing layer coating on the middle layer with a thickness of 60um. The drying temperature of the coating machine is 80°C and the speed is 2m / min.

[0096] Step 4: Use a coating machine to evenly coat the prepared ink-fixing layer coating on the ink-absorbing layer with a thickness of 100um. The drying temperature of the coating machine is 80°C and the speed is 2m / min.

[0097] Embodiment 6:

[0098] In addition to the above, the thermal transfer paper provided by the present invention can also be configured with an ink absorbing layer as follows:

[0099] The ink-absorbing layer includes the following raw materials in parts by weight: 55 parts of non-ionic polyurethane emulsion, 30 parts of hydrophobic matting powder, 10 parts of cationic color fixing agent, 25 parts of deionized water, 2 parts of barium sulfate, 2 parts of non-water-soluble plasticizer, 5 parts of non-water-soluble antioxidant, 2 parts of defoamer, 2 parts of dispersant, 2 parts of wetting agent, 2 parts of surfactant, 2 parts of leveling agent, 2 parts of coupling agent, and 2 parts of water repellent. The waterproof functional layer includes the following components in parts by weight: 50 parts of water-based polyurethane emulsion, 20 parts of TPU powder, 25 parts of anhydrous ethanol, 0.4 parts of thickener, 2 parts of defoamer, 2 parts of dispersant, 2 parts of wetting agent, 2 parts of surfactant, and 2 parts of leveling agent.

[0100] Based on the setting of the ink absorbing layer in the thermal transfer paper described in this embodiment, the preparation method of the thermal transfer paper includes the following steps:

[0101] Step 1: Laminate the base paper and TPU film;

[0102] Step 2: Evenly coat the pure acrylate in the middle layer on the TPU layer through a coater with a thickness of 10um. The drying temperature of the coater is 80°C and the speed is 2m / min.

[0103] Step 3: Use a coating machine to evenly coat the prepared ink-absorbing layer coating on the middle layer with a thickness of 60um. The drying temperature of the coating machine is 80°C and the speed is 2m / min.

[0104] Step 4: Use a coating machine to evenly coat the prepared ink-fixing layer coating on the ink-absorbing layer with a thickness of 100um. The drying temperature of the coating machine is 80°C and the speed is 2m / min.

[0105] Embodiment 7:

[0106] In addition to the above, the thermal transfer paper provided by the present invention can also be configured with an ink absorbing layer as follows:

[0107] The ink-absorbing layer includes the following raw materials in parts by weight: 55 parts of non-ionic polyurethane emulsion, 30 parts of hydrophobic matting powder, 10 parts of cationic color fixing agent, 25 parts of deionized water, 2 parts of barium sulfate, 2 parts of non-water-soluble plasticizer, 5 parts of non-water-soluble antioxidant, 2 parts of defoamer, 2 parts of dispersant, 2 parts of wetting agent, 2 parts of surfactant, 2 parts of leveling agent, 2 parts of coupling agent, and 2 parts of water repellent. The waterproof functional layer includes the following components in parts by weight: 50 parts of water-based hot melt adhesive, 20 parts of TPU powder, 2 parts of defoamer, 2 parts of dispersant, 2 parts of wetting agent, 2 parts of surfactant, and 2 parts of leveling agent.

[0108] Based on the setting of the ink absorbing layer in the thermal transfer paper described in this embodiment, the preparation method of the thermal transfer paper includes the following steps:

[0109] Step 1: Laminate the base paper and TPU film;

[0110] Step 2: Evenly coat the pure acrylate in the middle layer on the TPU layer through a coater with a thickness of 10um. The drying temperature of the coater is 80°C and the speed is 2m / min.

[0111] Step 3: Use a coating machine to evenly coat the prepared ink-absorbing layer coating on the middle layer with a thickness of 60um. The drying temperature of the coating machine is 80°C and the speed is 2m / min.

[0112] Step 4: Use a coating machine to evenly coat the prepared ink-fixing layer coating on the ink-absorbing layer with a thickness of 100um. The drying temperature of the coating machine is 80°C and the speed is 2m / min.

[0113] Embodiment 8:

[0114] In addition to the above, the thermal transfer paper provided by the present invention can also be configured with an ink absorbing layer as follows:

[0115] The ink-absorbing layer includes the following raw materials in parts by weight: 55 parts of non-ionic polyurethane emulsion, 30 parts of hydrophobic matting powder, 25 parts of deionized water, 2 parts of barium sulfate, 2 parts of non-water-soluble plasticizer, 5 parts of non-water-soluble antioxidant, 2 parts of defoamer, 2 parts of dispersant, 2 parts of wetting agent, 2 parts of surfactant, 2 parts of leveling agent, 2 parts of coupling agent, and 2 parts of water repellent. The waterproof functional layer includes the following components in parts by weight: 60 parts of water-based hot melt adhesive, 30 parts of TPU powder, 25 parts of anhydrous ethanol, 0.4 parts of thickener, 2 parts of defoamer, 2 parts of dispersant, 2 parts of wetting agent, 2 parts of surfactant, and 2 parts of leveling agent.

[0116] Based on the setting of the ink absorbing layer in the thermal transfer paper described in this embodiment, the preparation method of the thermal transfer paper includes the following steps:

[0117] Step 1: Laminate the base paper and TPU film;

[0118] Step 2: Evenly coat the pure acrylate in the middle layer on the TPU layer through a coater with a thickness of 10um. The drying temperature of the coater is 80°C and the speed is 2m / min.

[0119] Step 3: Use a coating machine to evenly coat the prepared ink-absorbing layer coating on the middle layer with a thickness of 60um. The drying temperature of the coating machine is 80°C and the speed is 2m / min.

[0120] Step 4: Use a coating machine to evenly coat the prepared ink-fixing layer coating on the ink-absorbing layer with a thickness of 100um. The drying temperature of the coating machine is 80°C and the speed is 2m / min.

[0121] Specifically, the performance test results of Examples 1-8 are shown in Table 1.

[0122] Table 1 Performance test results of Examples 1-8

[0123] Number / Performance Print clarity Color Saturation Ink drying speed Wash 5 times 1 better better Slightly better Slightly better 2 better better very good very good 3 better better better better 4 better better Slightly slower Poor 5 Slightly worse better Slow Poor 6 Poor better No Very bad 7 Slightly worse better better better 8 Very bad Slightly worse Slightly slower better

[0124] Results Analysis

[0125] In Examples 1, 2, and 3, as the polyurethane resin, ink-absorbing filler, and thickness of the ink-absorbing layer increase, the printing clarity and ink drying speed are proportional, the color saturation remains unchanged, and the water washing performance increases proportionally with the increase of TPU powder and thickness in the ink-fixing layer.

[0126] In Example 4, the reduction in the amount of polyurethane resin and ink-absorbing filler and the reduction in the thickness of the ink-absorbing layer resulted in a slower ink drying speed, and the reduction in the amount of TPU in the ink-fixing layer and the thinning of the thickness resulted in poor waterproof performance.

[0127] In Example 5, excessive amounts of polyurethane resin and ink-absorbing filler lead to decreased adhesion to the intermediate layer, easy detachment of the coating, and increased thickness of the ink-fixing layer, resulting in decreased print clarity and drying speed.

[0128] In Example 6, the resin of the ink-fixing layer was replaced. The total amount of ink absorbed by the water-based polyurethane was less than that of the water-based hot melt adhesive, so the ink could not be completely dried and was deposited on the surface of the film layer. After washing with water, serious discoloration occurred.

[0129] In Example 7, the anhydrous ethanol and thickener in the ink-fixing layer were removed, and the printing clarity decreased. The reason was that the TPU powder could not be evenly dispersed in the system due to the low viscosity of the system, and a uniform ink absorption amount could not be obtained.

[0130] In Example 8, the cationic color fixing agent was removed, and the print clarity, color saturation and ink drying speed all decreased, indicating that the cationic color fixing agent played an effect of increasing the ink absorption amount and fixing the dye molecules in the ink absorption layer.

[0131] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A thermal transfer paper, characterized in that: It includes a base paper, a TPU layer, an intermediate layer, an ink absorbing layer and an ink fixing layer arranged in sequence from bottom to top; Pure acrylic ester is provided in the middle layer to enhance the bonding effect between the ink-absorbing layer and the TPU layer; The ink-absorbing layer comprises the following raw materials expressed in parts by weight: 40-50 parts of non-ionic polyurethane emulsion, 10-20 parts of hydrophobic matting powder, 1-7 parts of cationic color fixing agent, 10-20 parts of deionized water, 1-2 parts of barium sulfate, 1-3 parts of non-water-soluble plasticizer, 1-5 parts of non-water-soluble antioxidant, 1-2 parts of defoaming agent, 1-2 parts of dispersant, 1-2 parts of wetting agent, 1-2 parts of surfactant, 1-2 parts of leveling agent, 1-2 parts of coupling agent, and 1-2 parts of water repellent; The solid ink layer includes the following raw materials expressed in parts by weight: 40-50 parts of water-based hot melt adhesive, 15-25 parts of TPU powder, 10-20 parts of anhydrous ethanol, 0.1-0.4 parts of thickener, 1-2 parts of dispersant, 1-2 parts of wetting agent, 1-2 parts of surfactant, 1-2 parts of leveling agent, and 1-2 parts of defoaming agent.

2. The thermal transfer paper according to claim 1, characterized in that: The TPU powder is evenly dispersed in the aqueous hot melt adhesive emulsion, and the TPU powder and the aqueous hot melt adhesive emulsion form a microporous structure.

3. The thermal transfer paper according to claim 1, characterized in that: The cationic color fixing agent is any one of polyvinylamine, polyethyleneimine, polydimethyldiallylammonium chloride, a high polymerization degree polyamine type cationic color fixing agent or polyvinylbenzyltrimethylammonium chloride.

4. The thermal transfer paper according to claim 1, characterized in that: The water repellent is any one of ammonium zirconium carbonate, polyamide polyurea resin, urea-formaldehyde resin, melamine formaldehyde resin, modified glyoxal or formaldehyde.

5. The thermal transfer paper according to claim 1, characterized in that: The surfactant is set to be any one of oleic acid diethanolamide, hexadecyltrimethylammonium chloride, dodecyldimethylbetaine or sodium dodecyldiphenyl ether disulfonate.

6. A method for preparing thermal transfer paper, characterized in that: The method for preparing the thermal transfer paper according to any one of claims 1 to 5 specifically comprises the following steps: Step 1: Laminate the base paper and TPU film; Step 2: Evenly coat the pure acrylate in the middle layer on the TPU layer through a coater with a thickness of 10um. The drying temperature of the coater is 80°C and the speed is 2m / min. Step 3: Use a coating machine to evenly coat the prepared ink-absorbing layer coating on the middle layer with a thickness of 40-50um. The drying temperature of the coating machine is 80°C and the speed is 2m / min. Step 4: Use a coating machine to evenly coat the prepared ink-fixing layer coating on the ink-absorbing layer with a thickness of 60-80um. The drying temperature of the coating machine is 80°C and the speed is 2m / min.

7. The method for preparing thermal transfer paper according to claim 6, characterized in that: The preparation process of the ink-absorbing layer coating is specifically as follows: Step 1, weigh the raw materials by weight; Step 2: Pour the dispersant, wetting agent, leveling agent, surfactant, defoamer and deionized water weighed in step 1 into a reaction kettle at room temperature, and stir at a speed of 300-500 r / min for 2-3 minutes; Step 3, pour the weighed polyurethane emulsion into the reaction kettle and stir at 500-800 r / min for 5-10 minutes; Step 4: Pour the weighed hydrophobic matting powder and coupling agent into the reaction kettle and stir at 1200-1600 r / min for 20-30 minutes; Step 5, pour the weighed precipitated barium sulfate, cationic color fixing agent, water-insoluble plasticizer, and water-insoluble antioxidant into the reaction kettle, and stir at 500-800 r / min for 5-10 minutes; Step 6: Slowly pour the water repellent weighed in step 1 into the reaction kettle and stir at 300-500 r / min for 3-5 minutes.

8. The method for preparing thermal transfer paper according to claim 6, characterized in that: The preparation process of the ink-fixing layer coating is as follows: Step 1), weigh the raw materials by weight; Step 2), pour the defoamer, dispersant, wetting agent, leveling agent, surfactant, deionized water and water-based hot melt adhesive weighed in step 1) into the reaction kettle at room temperature, and stir at 300-500 r / min for 2-3 minutes; Step 3), pour the weighed thickener into the weighed anhydrous ethanol, stir at 500-800r / min for 2-3 minutes to fully dissolve it; Step 4), pour the dissolved anhydrous ethanol-thickener mixture into the reactor and stir at 1200-1600r / min for 5-10 minutes; Step 5) Pour the weighed TPU powder into the reactor and stir at 1500-2000 r / min for 20-30 minutes.