High-scratch-resistant digital transfer film, and preparation method and application thereof

Abstract

This invention belongs to the field of printing materials technology, and provides a highly scratch-resistant digital transfer film, its preparation method, and its application. This invention utilizes latex, a fixing agent, a scratch-resistant agent, and fillers as the main raw material components of the fixing layer of the digital transfer film. It employs a combination of two latexes, A and B, with different Tg values, which improves the coating's hardness while providing a certain degree of flexibility. A cationic resin-type fixing agent is used, along with modified polysiloxanes and / or waxes as scratch-resistant agents. The filler particle size (D90) is limited to 200-1000 nm. This results in a digital transfer film that, when used for printing, maintains a smooth surface without powder adhesion or peeling, while ensuring normal use. The fixing layer exhibits high strength and scratch resistance, withstanding at least 30 washes and even up to 42 washes. The coating also demonstrates high strength and minimal wear in scratch resistance tests.

Description

Technical Field

[0001] This invention relates to the field of printing materials technology, and more specifically, to a highly scratch-resistant digital transfer film, its preparation method, and its application. Background Technology

[0002] In recent years, heat transfer printing technology has received widespread attention both domestically and internationally. Heat transfer printing is not limited by the shape of the product and features simple operation and exquisite, delicate printed products. Among its components, heat transfer film is one of the core technologies of digital printing, and the fixing layer of heat transfer film is one of its core technologies. The fixing layer is generally composed of latex, fixing agent, filler, leveling agent, and additives.

[0003] Currently, the color-fixing layer of heat transfer printing films is made with water-based coatings. While water-based coatings are environmentally friendly, the color-fixing layer prepared with them is prone to problems such as poor coating adhesion and scratch resistance. The less latex in the color-fixing layer, the worse the film-forming properties, and consequently, the worse the color-fixing layer's adhesion and scratch resistance. Conversely, the more latex, the better the film-forming properties, resulting in better color-fixing layer adhesion and scratch resistance. However, if the film-forming properties are too good, the transfer process is prone to problems such as peeling and rough edges on the image. How to improve the adhesion and scratch resistance of the color-fixing layer while ensuring transfer quality has become a challenge for digital transfer films.

[0004] Therefore, there is an urgent need to develop a digital transfer film that, while ensuring normal use, does not exhibit problems such as peeling or rough edges on the image, has good film-forming properties, high adhesion, and excellent scratch resistance. Summary of the Invention

[0005] This invention aims to solve at least one of the technical problems existing in the prior art. To this end, this invention proposes a highly scratch-resistant digital transfer film, its preparation method, and its application. The digital transfer film provided by this invention can be used for printing. While ensuring normal use, the film surface is smooth, and the color-fixing layer has high adhesion and good scratch resistance (it can withstand at least 30 washes, and even up to 42 washes; the coating has high strength and high adhesion; in scratch resistance tests, wear is slight, and scratch resistance is good).

[0006] A first aspect of the present invention provides a highly scratch-resistant digital transfer film.

[0007] Specifically, a highly scratch-resistant digital transfer film includes a color-fixing layer, wherein the color-fixing layer comprises the following raw material components:

[0008] Latex, color fixative, scratch resistant agent, filler;

[0009] The latex includes latex A and latex B, wherein the glass transition temperature of latex A is 0-45℃, and the glass transition temperature of latex B is greater than 45℃ and less than or equal to 100℃.

[0010] The fixing agent is a cationic resin type fixing agent;

[0011] The scratch-resistant agent is a modified polysiloxane and / or a wax-like substance;

[0012] The particle size D90 of the filler is 200-1000 nm.

[0013] The cationic resin-type fixing agent used in this invention has film-forming properties, but the resulting coating exhibits high rigidity, poor flexibility, and low elongation, resulting in significant brittleness. Therefore, this invention also adds latex to improve the coating's flexibility. Latex A has a lower glass transition temperature, which improves the coating's flexibility, but its hardness is low. Latex B has a higher glass transition temperature and higher hardness, but it is brittle and lacks flexibility. Combining latex A and latex B with different glass transition temperatures (Tg) can improve both the coating's hardness and its flexibility. A higher latex content results in better film-forming properties, scratch resistance, and adhesion, but peeling is common. Therefore, this invention also adds fillers with specific particle sizes. Overly large filler particle sizes lead to a grainy coating surface, making it easy to scratch off, resulting in decreased coating strength, scratch resistance, and water resistance, and a less smooth film surface with powder adhesion. Conversely, overly small filler particle sizes result in a lack of surface roughness, also leading to a less smooth film surface and powder adhesion. In addition, the present invention adds modified polysiloxane and / or waxes as scratch-resistant agents. The addition of modified polysiloxane can increase the hardness of latex and reduce surface friction, while the smooth waxes form a protective layer on the coating surface after film formation. The present invention makes the film surface smooth, scratch-resistant and highly durable by adding scratch-resistant agents.

[0014] Preferably, the cationic resin-type fixing agent includes at least one of amine-formaldehyde resin-type dicyandiamide-formaldehyde condensate, polyamine condensate, and phenolic condensate.

[0015] More preferably, the cationic resin-type fixing agent includes modified dicyandiamide-formaldehyde resin and / or polydimethylpropylammonium chloride.

[0016] Preferably, the glass transition temperature of latex A is 0-20°C.

[0017] Preferably, the glass transition temperature of latex B is 55-65°C.

[0018] Preferably, latex A comprises at least one of acrylic latex, polyurethane latex, styrene-butadiene latex, bio-latex, nitrile latex, chloroprene latex, hydroxyl latex, styrene-butadiene pyridine latex, butyl latex, isoprene latex, polysulfide latex, styrene-acrylic latex, carboxylated styrene-butadiene latex, ethylene-propylene latex, and butadiene latex.

[0019] Preferably, the latex B comprises at least one of polycarbonate, polyurethane emulsion containing hydrophilic monomers, and acrylate copolymer emulsion containing hydrophilic monomers.

[0020] Preferably, the polyurethane emulsion containing hydrophilic monomers is a polyurethane emulsion containing at least one of (meth)acrylic acid, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, maleic anhydride, and dimethylolpropionic acid.

[0021] Preferably, the acrylate copolymer emulsion containing hydrophilic monomers is an acrylate copolymer emulsion containing at least one of (meth)acrylic acid, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, maleic anhydride, and dimethylolpropionic acid.

[0022] Preferably, the mass ratio of latex A to latex B is (1:10)-(10:1).

[0023] Preferably, the modified polysiloxane is at least one of amino-modified polydimethylsiloxane, epoxy-modified polydimethylsiloxane, isopropylene-modified polydimethylsiloxane, and mercapto-modified polydimethylsiloxane.

[0024] Preferably, the wax is at least one of polyethylene wax, polypropylene wax, silicone wax, and Fischer-Tropsch wax.

[0025] Preferably, the particle size D90 of the filler is 300-1000 nm.

[0026] Preferably, the filler is zinc stearate and / or nanofiller.

[0027] More preferably, the filler is a combination of stearate and nanofiller.

[0028] Preferably, the stearate is one of zinc stearate, calcium stearate, and magnesium stearate.

[0029] Preferably, the nanofiller comprises one of gaseous silica, nano-talc, nano-cellulose, and graphene fiber. The nanofiller is characterized by high hardness.

[0030] The end groups on latex contain at least one self-crosslinking group selected from hydroxyl, carboxyl, carboxymethyl, and aldehyde groups. These groups can undergo crosslinking reactions with metal ions such as zinc stearate, calcium stearate, and magnesium stearate, thereby improving the adhesion between the filler and the coating. Nanofillers have small particle size, high hardness, and good hydrophilicity. The coating formed by these fillers exhibits excellent density and smoothness. Simultaneously, the fillers can reduce transfer peeling caused by excessive latex usage. Therefore, this invention employs a combination of high-hardness nanofillers and fillers containing metal ions, which helps improve the density, smoothness, and water resistance of the color-fixing layer coating. Furthermore, the addition of fillers reduces transfer peeling caused by excessive latex usage.

[0031] Preferably, the leveling agent is selected from polyether-modified siloxane.

[0032] Preferably, the digital transfer film further includes a release layer.

[0033] Preferably, the color-fixing layer comprises the following raw material components in parts by weight:

[0034] 20-50 parts latex

[0035] Fixing agent 15-30 parts

[0036] Scratch-resistant agent 1-10 parts

[0037] 15-50 parts of filler.

[0038] More preferably, the color-fixing layer comprises the following raw material components in parts by weight:

[0039] 20-45 parts latex

[0040] Fixing agent 17-25 parts

[0041] 2-8 parts of scratch-resistant agent

[0042] 22-40 parts of filler.

[0043] Preferably, the color-fixing layer further includes a leveling agent, wherein the leveling agent comprises 1-10 parts by weight.

[0044] More preferably, the color-fixing layer further includes a leveling agent, which is 5-6 parts by weight.

[0045] A second aspect of the present invention provides a method for preparing a highly scratch-resistant digital transfer film.

[0046] A method for preparing a highly scratch-resistant digital transfer film includes the following steps:

[0047] The raw material components are mixed, coated, and dried to obtain the highly scratch-resistant digital transfer film.

[0048] Preferably, the coating method includes one of slot coating, slope coating, air knife coating, anilox roller coating, and doctor blade coating.

[0049] Preferably, the coating is applied to the release layer, dried, and then a color-fixing layer is formed to obtain a digital transfer film containing a color-fixing layer.

[0050] Preferably, the drying temperature is 100-150°C, and / or the drying time is 0.5-10 min.

[0051] More preferably, the drying temperature is 130-140°C, and / or the drying time is 1-5 minutes.

[0052] Preferably, the coating amount is 2-4 g / m². 2 .

[0053] A third aspect of the present invention provides an application of a digital transfer film.

[0054] Application of a highly scratch-resistant digital transfer film in heat transfer printing.

[0055] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0056] This invention utilizes latex, a color-fixing agent, a scratch-resistant agent, and fillers as the main raw material components of the color-fixing layer of a digital transfer film. It employs a combination of two latexes, A and B, with different Tg values, which improves the coating's hardness while maintaining a degree of flexibility. A cationic resin-type color-fixing agent is used, along with modified polysiloxanes and / or waxes as scratch-resistant agents. The filler particle size (D90) is limited to 200-1000 nm. This results in a digital transfer film that, when used for printing, exhibits high color-fixing strength and excellent scratch resistance, capable of withstanding at least 30 washes and even up to 42 washes, while maintaining normal operation. The coating also demonstrates high strength and minimal wear during scratch resistance testing. Detailed Implementation

[0057] To enable those skilled in the art to more clearly understand the technical solutions described in this invention, the following embodiments are provided for illustration. It should be noted that the following embodiments do not constitute a limitation on the scope of protection claimed by this invention.

[0058] Unless otherwise specified, the raw materials, reagents or devices used in the following examples are available from conventional commercial sources or can be obtained by existing known methods.

[0059] Example 1

[0060] A highly scratch-resistant digital transfer film includes a color-fixing layer and a release layer, wherein the coating amount of the color-fixing layer is 3 g / m². 2The raw material components of the color-fixing layer include 35 parts latex (15 parts latex A and 30 parts latex B), 25 parts color-fixing agent, 6 parts leveling agent, 2 parts scratch-resistant agent and 22 parts filler. The specific components and their amounts are shown in Table 1 and Table 2.

[0061] A highly scratch-resistant digital transfer film, comprising the following steps:

[0062] (1) Preparation of coating: Water, latex, color fixative, scratch resistant agent, filler and leveling agent are added to the mixing tank in sequence and stirred. After stirring, the mixture is filtered and defoamed.

[0063] (2) Apply the coating to the release layer and dry it at 130°C for 1 minute to obtain a digital transfer film containing a color-fixing layer.

[0064] Examples 2-6

[0065] The highly scratch-resistant digital transfer films of Examples 2-6 and their preparation methods are the same as those of Example 1, except that the components and their amounts are different, as shown in Table 1 and Table 2.

[0066] Table 1. Amounts of raw material components (dry weight parts) in each embodiment.

[0067] Components Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Fixative 25 25 17.5 20 23 20 Latex A 15 30 20 15 10 15 Latex B 30 15 25 20 13 20 filler 22 22 30 31 40 31 Scratch-resistant agent 2 2 1.5 8 8 8 Leveling agent 6 6 6 6 6 6

[0068] Table 2. Types of raw material components in each embodiment.

[0069]

[0070] Comparative Example 1

[0071] This comparative example provides a digital transfer film, which differs from Example 1 in that the fixing agent is replaced with an equal weight of inorganic salt calcium chloride.

[0072] Comparative Example 2

[0073] This comparative example provides a digital transfer film, which differs from Example 1 in that the fixing agent is replaced with an equal weight of polyacrylic acid.

[0074] Comparative Example 3

[0075] This comparative example provides a digital transfer film, which differs from Example 1 in that all of latex B is replaced with an equal weight of latex A, i.e., Comparative Example 2 contains only latex A (a polyacrylic emulsion with methyl methacrylate as the hard monomer and butyl acrylate as the soft monomer, Tg = 0°C).

[0076] Comparative Example 4

[0077] This comparative example provides a digital transfer film, which differs from Example 1 in that the filler is replaced with large-particle-size calcium carbonate with a D90 of 10 μm.

[0078] Comparative Example 5

[0079] This comparative example provides a digital transfer film, which differs from Example 1 in that the filler is replaced with small-particle-size calcium carbonate with a D90 of 150 nm.

[0080] Comparative Example 6

[0081] This comparative example provides a digital transfer film, which differs from Example 1 in that the scratch-resistant agent is replaced with an equal weight of filler, i.e., Comparative Example 4 does not contain scratch-resistant agent.

[0082] Comparative Example 7

[0083] This comparative example provides a digital transfer film, which differs from Example 1 in that the scratch-resistant agent is replaced with an equal weight of polydimethylsiloxane.

[0084] Comparative Example 8

[0085] This comparative example provides a digital transfer film, which differs from Example 1 in that the filler is replaced with equal weights of latex (where the weight ratio of latex A to latex B is 1:2) 14.5 parts of latex B and 7.5 parts of latex A, i.e., Comparative Example 5 does not contain filler.

[0086] Product effectiveness test

[0087] The digital transfer films prepared in the above embodiments and comparative examples were tested. Test items included powder adhesion, peeling, image transfer rate, ink retention, coating strength, and coating scratch resistance. Specific test methods are as follows:

[0088] (1) Powder adhesion: at 0.125m 2 A standard CMYK image (printing color mode) is printed on the digital transfer film. High-polymer hot melt adhesive powder is evenly sprinkled on its surface, and after shaking off the powder, the weight ratio of the adhesive powder in the non-image areas is measured. If the amount of adhesive powder is less than 5%, it means that there is no adhesive powder, and if it is more than 5%, it means that there is too much adhesive powder, which will affect the subsequent transfer printing.

[0089] (2) Peeling condition: Tear the ink block of the image by hand and observe the image edge with a magnifying glass to see if there are any jagged edges. If the image boundary is clear and there are no jagged edges, it means that the printing precision is high and there is no peeling; if the image boundary has jagged edges, it means that the printing precision of the image is low and there is more peeling.

[0090] (3) Coating strength: Place the coated digital transfer film upward on the wash resistance tester, brush it, and record the number of times the coating is washed until it breaks. The more wash resistance cycles, the higher the strength.

[0091] (4) Coating scratch resistance: Cut the coated digital transfer film into 5cm*23cm pieces and place them in a PARAM friction tester for testing. The test is conducted 20 times at a speed of 42 times / minute. The scratch wear of the coating is observed and expressed as 1-10, with 10 indicating the most severe wear and 1 indicating slight wear.

[0092] (5) Printing ink retention: The maximum amount of white ink that can be printed without ink flow.

[0093] (6) Image transfer rate: Take the transfer paper from the above embodiments and comparative examples, observe the ink residue on the transfer paper, and measure the weight ratio of the residual image after transfer. If there is no residual image on the transfer film, that is, the transfer rate is higher than 99%, it indicates that the transfer effect is good. If there are many traces of residual image on the transfer paper, that is, the transfer rate is lower than 80%, it indicates that the transfer effect is poor.

[0094] The test results are shown in Table 3.

[0095] Table 3 Performance test results of each embodiment and comparative example

[0096]

[0097]

[0098] As shown in Table 3, the highly scratch-resistant digital transfer film provided in Examples 1-6 of the present invention can withstand at least 30 washes, and even up to 42 washes. The coating has high strength and high adhesion. In the scratch resistance test, it reaches level 3 or above, with slight wear and good scratch resistance. It does not peel or stick to powder. Moreover, the printing and transfer performance are normal, which can ensure normal use.

[0099] In Comparative Example 1, when the fixing agent was replaced with inorganic calcium chloride, the strength and scratch resistance of the digital transfer film coating decreased because inorganic calcium chloride is prone to moisture absorption.

[0100] In Comparative Example 2, when the fixing agent was replaced with an equal weight of polyacrylic acid, powdering, slight peeling, coating strength, and ink retention during printing all occurred.

[0101] In Comparative Example 3, only Latex A was added to the system. Because Latex A is soft, sticky, and not slippery, the coating sticks to the powder, which leads to a significant decrease in the strength and scratch resistance of the resulting color-fixed layer.

[0102] In Comparative Example 4, when the filler was replaced with large-particle calcium carbonate, the coating surface was rough and the grainy texture was too strong due to the excessively large filler particle size. This made it easy to scratch off, resulting in a decrease in coating strength and scratch resistance. Furthermore, the film surface was not smooth enough and powder sticking occurred.

[0103] In Comparative Example 5, when the filler was replaced with small-particle-size calcium carbonate, the filler particle size was too small, resulting in a lack of smoothness on the membrane surface and powder adhesion.

[0104] In Comparative Example 6, the scratch-resistant agent can form a smooth protective layer on the film surface. Without the addition of the scratch-resistant agent, the film surface is not smooth enough, resulting in powder adhesion, and a decrease in scratch resistance and coating strength.

[0105] In Comparative Example 7, when the scratch-resistant agent was replaced with an equal weight of polydimethylsiloxane, powdering occurred, and the coating strength and scratch resistance both decreased.

[0106] In Comparative Example 8, no filler was added, and the proportion of latex in the coating increased. Although the coating strength and scratch resistance were improved to some extent and the film-forming properties were good, the coating film-forming properties were too good, which easily led to severe peeling, powdering, and poor waterproof performance.

Claims

1. A digital transfer film, characterized in that, It consists of a color-fixing layer and a release layer. By weight, the color-fixing layer comprises the following raw material components: It includes 20-50 parts latex, 15-35 parts color fixative, 1-10 parts scratch resistant agent, and 15-45 parts filler; The latex comprises latex A and latex B, wherein latex A has a glass transition temperature of 0-20°C, and latex B has a glass transition temperature of 55°C. 65℃; The fixing agent is a cationic resin type fixing agent; The scratch-resistant agent is a modified polysiloxane and / or a wax-like substance; The particle size D90 of the filler is 200-1000 nm.

2. The digital transfer film according to claim 1, characterized in that, The cationic resin-type fixing agent includes at least one of the following: amine-formaldehyde resin-type dicyandiamide-formaldehyde primary condensate, polyamine condensate, and phenolic condensate.

3. The digital transfer film according to claim 1, characterized in that, Latex A includes at least one of acrylic emulsion, polyurethane emulsion, styrene-butadiene emulsion, bio-latex, nitrile latex, chloroprene latex, hydroxyl latex, styrene-butadiene pyridine latex, butyl latex, isoprene latex, polysulfide latex, styrene-acrylic latex, carboxylated styrene-butadiene latex, ethylene-propylene latex, and butadiene latex.

4. The digital transfer film according to claim 1, characterized in that, The latex B includes at least one of polycarbonate, polyurethane emulsion containing hydrophilic monomers, and acrylate copolymer emulsion containing hydrophilic monomers.

5. The digital transfer film according to claim 1, characterized in that, The mass ratio of latex A to latex B is (1:10) - (10:1).

6. The digital transfer film according to claim 1, characterized in that, The modified polysiloxane is at least one of amino-modified polydimethylsiloxane, epoxy-modified polydimethylsiloxane, isopropylene-modified polydimethylsiloxane, and mercapto-modified polydimethylsiloxane.

7. The digital transfer film according to claim 1, characterized in that, The waxy substance is at least one of polyethylene wax, silicone wax, polypropylene wax, and Fischer-Tropsch wax.

8. The digital transfer film according to claim 1, characterized in that, The filler is stearate and / or nanofiller.

9. The digital transfer film according to claim 1, characterized in that, The color-fixing layer also includes a leveling agent, which is 1-10 parts by weight.

10. The method for preparing the digital transfer film according to any one of claims 1-9, characterized in that, Includes the following steps: The raw material components are mixed, coated, and dried to obtain the digital transfer film.

11. The application of the digital transfer film according to any one of claims 1-9 in heat transfer printing.

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