Flexographic printing and cold stamping holographic anti-counterfeiting foil with low transfer defects and preparation method of flexographic printing and cold stamping holographic anti-counterfeiting foil

Abstract

The invention discloses a flexographic printing and cold stamping holographic anti-counterfeiting foil with low transfer defects and a preparation method of the flexographic printing and cold stamping holographic anti-counterfeiting foil. The cold stamping holographic anti-counterfeiting foil comprises a base film layer, a release layer, an information layer, a reflecting layer and a protective layer which are sequentially stacked, the release layer, the information layer and the protective layer sequentially correspond to a release agent, an information layer coating and a protective layer coating, the base film is coated with the release agent, the information layer coating and the protective layer coating, and the release agent comprises wax modified organic silicon resin and composite resin. The information layer coating comprises low-molecular-weight polyurethane, high-acid-value acrylic resin, a nitrocellulose solution and dye color paste, and the protective layer coating comprises high-acid-value acrylic resin, a fluorine-modified leveling agent and nano calcium carbonate. Through a newly designed multi-layer raw material ratio and synergistic cooperation of all functional layers, transfer printing stress can be absorbed, transfer defects can be eliminated, and the pattern definition and the color aluminum fastness during cold stamping and the ink adhesive force and the printing efficiency during back-end flexographic printing are remarkably improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of cold stamping film, and particularly relates to a soft printing cold stamping holographic anti-counterfeiting foil with low transfer defects and a preparation method thereof. BACKGROUND

[0002] The soft printing cold stamping holographic anti-counterfeiting foil is an advanced printing material, which is widely used in the surface decoration and functional treatment of various substrates such as paper, paperboard and plastic film. However, the soft printing cold stamping holographic anti-counterfeiting foil has some defects in practical application. Firstly, white spot defects, which are mainly caused by uneven coating of the adhesive or incomplete transfer of the aluminum foil, resulting in white spots on the surface of the printed product, affecting the pattern integrity and aesthetics. Secondly, crack defects, which are prone to occur on the surface of the printed product due to the difference in thermal expansion coefficient of the materials or mechanical stress during the cold stamping process, reducing the product quality and durability. These defects not only affect the appearance of the product, but also may cause functional failure, increasing the production cost. In order to solve these problems, it is necessary to provide a soft printing cold stamping holographic anti-counterfeiting foil with low transfer defects. SUMMARY

[0003] Based on the deficiencies of the prior art, the present application provides a soft printing cold stamping holographic anti-counterfeiting foil with low transfer defects and a preparation method thereof.

[0004] The first aspect of the present application is to provide a soft printing cold stamping holographic anti-counterfeiting foil with low transfer defects, which comprises a base film layer, a release layer, an information layer, a reflective layer and a protective layer stacked in sequence. The release layer, the information layer and the protective layer are coated on the base film in sequence by a release agent, an information layer coating and a protective layer coating, and then baked to form a coating.

[0005] In some embodiments, the release agent comprises the following components by weight: wax-modified silicone resin 45-55 parts, composite resin 25-35 parts; The information layer coating comprises the following components by weight: low molecular weight polyurethane 60-70 parts, high acid value acrylic resin 20-30 parts, nitrocellulose solution 10-15 parts, dye paste 5-10 parts; The protective layer coating comprises the following components by weight: high acid value acrylic resin 65-75 parts, fluorine-modified leveling agent 3-7 parts, nano calcium carbonate 10-20 parts.

[0006] The high acid value acrylic acid herein refers to an acrylic acid resin with an acid value of 100 mg KOH / g or more.

[0007] In some embodiments, the wax-modified silicone resin is prepared by the following steps: S1: adding microcrystalline wax and crosslinking agent into a reaction kettle, and reacting under inert gas protection to generate wax-silane block; S2: mixing hydroxyl-terminated polydimethylsiloxane, platinum catalyst, inhibitor and wax-silane block, and adding a solvent to filter to obtain a wax-modified silicone resin.

[0008] It should be noted that the present application creatively provides a wax-modified silicone resin, which forms a unique "wax-silicon" block structure by chemical bonding of wax molecules and silane. The esterification reaction occurs between the hydroxyl group of the wax and the silane alkoxy group to generate a wax-grafted siloxane intermediate, and then a flexible silicon skeleton is formed through hydrolysis and polycondensation, while the crystallization characteristics of the wax chain are retained. In the cold pressing film, the wax chain floats on the surface when heated to form a super-smooth release surface, reducing the generation of white spots; the silicon skeleton provides high elasticity and buffering to ensure complete peeling of the stamping foil without residue.

[0009] In some embodiments, the crosslinking agent is selected from at least one of methyltrimethoxysilane, methyltriethoxysilane, and tetraethoxysilane; the inhibitor is selected from at least one of ethynylcyclohexanol and diethyl maleate; and the solvent is selected from at least one of isopropyl alcohol, propylene glycol methyl ether acetate, and methyl isobutyl ketone.

[0010] In some embodiments, the mass ratio of the microcrystalline wax to the hydroxyl-terminated polydimethylsiloxane is 1:2-3; the amount of the crosslinking agent is 15-17% of the mass of the hydroxyl-terminated polydimethylsiloxane; the platinum catalyst has a pt concentration of 2000-2500 ppm, and the amount of the platinum catalyst is 0.5-1% of the mass of the hydroxyl-terminated polydimethylsiloxane; and the amount of the inhibitor is 0.1-0.2% of the mass of the hydroxyl-terminated polydimethylsiloxane.

[0011] In some embodiments, in the S1 step, the temperature of the reaction kettle is 110-120℃, and the reaction time is 1.5-2 h; and in the S2 step, the mixing temperature is 120-140℃, the mixing time is 2-4 h, and the pore size of the filter core is 5-6 μm.

[0012] In some embodiments, the composite resin is mixed from polyether polyurethane, acrylate rubber, epoxy-modified acrylic resin, and silicone-acrylic copolymer at a mass ratio of 6-7:2-3:1-2:0.5-1.

[0013] In some embodiments, the weight average molecular weight of the low molecular weight polyurethane in the information layer coating is 5000-15000; the acid value of the high acid value acrylic resin in the information layer coating is ≥120 mg KOH / g; and the acid value of the high acid value acrylic resin in the protective layer coating is ≥150 mg KOH / g.

[0014] The second aspect of the present application is to provide a preparation method of a low transfer defect flexographic cold stamping holographic anti-counterfeiting foil, comprising the following steps: (1) The wax modified silicone resin and the composite resin are mixed according to the formula proportion, and a release agent is obtained, then the release agent is coated on the PET film, and the release layer is obtained after drying, and the coating dryness is 0.5-1 g / m 2 ; (2) The low molecular weight polyurethane and the high acid value acrylic resin are mixed according to the formula proportion, and the nitrocellulose solution and the dye paste are mixed uniformly to obtain an information layer coating, then the information layer coating is coated on the release layer of step (1), and the information layer is obtained after drying and molding, and the coating dryness is 1-2 g / m 2 ; (3) The information layer of step (2) is vacuum plated with aluminum to obtain a reflection layer; (4) The high acid value acrylic resin and the fluorine modified leveling agent are mixed uniformly according to the formula proportion, and the nano calcium carbonate is mixed uniformly to obtain a protective layer coating, then the protective layer coating is coated on the reflection layer of step (3), and the protective layer is obtained after drying, and the coating dryness is 1.5-3 g / m 2 ; The low transfer defect flexographic cold stamping holographic anti-counterfeiting foil is obtained.

[0015] In some embodiments, in step (1), the stirring temperature is 50-60℃, and the stirring time is 30-40 min; in step (2), the stirring temperature is 40-45℃, and the stirring time is 40-50 min.

[0016] Compared with the prior art, the present application has the following beneficial effects: 1. The present application significantly improves the excellent performance of the flexographic cold stamping holographic anti-counterfeiting foil through the synergistic design of the multifunctional layer, the release layer realizes low peeling force and high interface stability through the wax modified silicone resin, the cold stamping foil is completely peeled off without residue, and the generation of white spots is reduced; the information layer absorbs the transfer stress through the polyurethane-acrylic resin crosslinked network, and eliminates the white spot and crack defects; the protective layer enhances the adhesion and flexibility to the curved surface through the high acid value resin and nano filler.

[0017] 2. The present application realizes one-time molding through the coating process, the release layer interface realizes smooth peeling, the buffer layer elastically absorbs stress, and the protective layer chemical bonding ensures adhesion, which can completely meet the cold stamping transfer requirements, in addition, the phase separation self-organization characteristics of the release layer can improve the coating efficiency, and the nano calcium carbonate toughening technology of the protective layer can reduce the resin consumption, which greatly reduces the energy consumption. DETAILED DESCRIPTION

[0018] The present application will be further described in detail below in conjunction with the examples.

[0019] Embodiment 1 A low-transfer-defect flexographic cold stamping holographic anti-counterfeiting foil, comprising a base film layer, a release layer, an information layer, a reflective layer and a protective layer which are sequentially stacked; the release layer, the information layer and the protective layer are sequentially coated with a release agent, an information layer coating and a protective layer coating on the base film to form a coating which is dried to obtain the low-transfer-defect flexographic cold stamping holographic anti-counterfeiting foil. The release agent comprises the following components by weight: 50 parts of wax-modified silicone resin and 30 parts of composite resin; wherein the composite resin is mixed by polyurethane, acrylate rubber, epoxy-modified acrylic resin and silicone-acrylic copolymer in a mass ratio of 6:3:1.5:1. The wax-modified silicone resin is prepared by the following steps: S1: microcrystalline wax and methyltrimethoxysilane are added to a reaction kettle at 115°C and reacted for 2 h under inert gas protection to form wax-silane block; wherein the mass ratio of microcrystalline wax to hydroxyl-terminated polydimethylsiloxane is 1:2, and the amount of crosslinking agent is 15% of the mass of hydroxyl-terminated polydimethylsiloxane; S2: hydroxyl-terminated polydimethylsiloxane, platinum catalyst with a platinum concentration of 2200 ppm, ethynylcyclohexanol and wax-silane block are mixed at 130°C for 3 h, and then isopropanol is added and filtered through a filter core with a pore size of 5 μm to obtain the wax-modified silicone resin; wherein the amount of platinum catalyst is 1% of the mass of hydroxyl-terminated polydimethylsiloxane, and the amount of inhibitor is 0.15% of the mass of hydroxyl-terminated polydimethylsiloxane.

[0020] The information layer coating comprises the following components by weight: 65 parts of low molecular weight polyurethane, 25 parts of high acid value acrylic resin with an acid value of ≥120 mg KOH / g, 15 parts of nitrocellulose solution and 8 parts of dye paste; wherein the weight average molecular weight of the low molecular weight polyurethane is 5000-15000.

[0021] The protective layer coating comprises the following components by weight: 70 parts of high acid value acrylic resin with an acid value of ≥150 mg KOH / g, 5 parts of fluorine-modified leveling agent and 15 parts of nano calcium carbonate.

[0022] The above-mentioned low-transfer-defect flexographic cold stamping holographic anti-counterfeiting foil is prepared by the following steps: (1) The wax-modified silicone resin and the composite resin are stirred at 55°C for 35 min according to the formula proportion to obtain a release agent, and then the release agent is coated on a 12 μm PET film, and the release layer is obtained after drying, and the coating dryness is 0.8 g / m 2 ; (2) The low molecular weight polyurethane, the high acid value acrylic resin, the nitrocellulose solution and the dye color paste are mixed according to the formula proportion at 45℃ for 45 min to obtain an information layer coating, and then the information layer coating is coated on the release layer of step (1) to obtain an information layer after drying and molding, and the coating dry weight is 1.5 g / m 2 ; (3) The information layer of step (2) is vacuum plated with aluminum to obtain a 130 nm reflective layer; (4) The high acid value acrylic resin and the fluorine modified leveling agent are mixed according to the formula proportion to obtain a protective layer coating, and then the protective layer coating is coated on the reflective layer of step (3) to obtain a protective layer after drying, and the coating dry weight is 2.3 g / m 2 ; to obtain a soft printing cold stamping holographic anti-counterfeiting foil with low transfer defects.

[0023] Example 2 The difference is only that: The release agent comprises the following components in parts by weight: wax modified silicone resin 55 parts, composite resin 35 parts; wherein the composite resin is mixed by polyurethane, acrylic rubber, epoxy modified acrylic resin and silicone-acrylic copolymer in a mass ratio of 7:3:2:1.

[0024] The information layer coating comprises the following components in parts by weight: low molecular weight polyurethane 70 parts, high acid value acrylic resin with acid value ≥120 mg KOH / g 30 parts, nitrocellulose solution 15 parts, dye color paste 10 parts.

[0025] The protective layer coating comprises the following components in parts by weight: high acid value acrylic resin with acid value ≥150 mg KOH / g 75 parts, fluorine modified leveling agent 7 parts, nano calcium carbonate 20 parts.

[0026] Example 3 The difference is only that: The release agent comprises the following components in parts by weight: wax modified silicone resin 45 parts, composite resin 25 parts; wherein the composite resin is mixed by polyurethane, acrylic rubber, epoxy modified acrylic resin and silicone-acrylic copolymer in a mass ratio of 6:2:1:0.5.

[0027] The information layer coating comprises the following components in parts by weight: low molecular weight polyurethane 60 parts, high acid value acrylic resin with acid value ≥120 mg KOH / g 20 parts, nitrocellulose solution 10 parts, dye color paste 9 parts.

[0028] The protective layer coating includes the following components by weight: a high-acid-value acrylic resin with an acid value ≥ 150 mg KOH / g 65 parts, a fluorine-modified leveling agent 3 parts, nano calcium carbonate 10 parts.

[0029] Example 4 The example is basically identical to Example 1, with the only difference being that: The wax-modified silicone resin is prepared by the following steps: S1: Microcrystalline wax and methyl triethoxysilane are added to a reaction kettle at 120°C, and reacted for 2 h under inert gas protection to form wax-silane block; wherein the mass ratio of microcrystalline wax to hydroxyl-terminated polydimethylsiloxane is 1:3, and the amount of crosslinking agent is 17% of the mass of hydroxyl-terminated polydimethylsiloxane; S2: Hydroxyl-terminated polydimethylsiloxane, platinum catalyst with a Pt concentration of 2000-2500 ppm, diethyl maleate, and wax-silane block are mixed at 140°C for 4 h, and after adding propylene glycol methyl ether acetate, filtering under a filter core aperture of 6 μm to obtain the wax-modified silicone resin; wherein the amount of platinum catalyst is 1% of the mass of hydroxyl-terminated polydimethylsiloxane, and the amount of inhibitor is 0.2% of the mass of hydroxyl-terminated polydimethylsiloxane.

[0030] Example 5 The example is basically identical to Example 1, with the only difference being that: The wax-modified silicone resin is prepared by the following steps: S1: Microcrystalline wax and tetraethoxysilane are added to a reaction kettle at 110°C, and reacted for 1.5 h under inert gas protection to form wax-silane block; wherein the mass ratio of microcrystalline wax to hydroxyl-terminated polydimethylsiloxane is 1:2, and the amount of crosslinking agent is 15% of the mass of hydroxyl-terminated polydimethylsiloxane; S2: Hydroxyl-terminated polydimethylsiloxane, platinum catalyst with a Pt concentration of 2000 ppm, ethynylcyclohexanol, and wax-silane block are mixed at 120°C for 2 h, and after adding methyl isobutyl ketone, filtering under a filter core aperture of 5 μm to obtain the wax-modified silicone resin; wherein the amount of platinum catalyst is 0.5% of the mass of hydroxyl-terminated polydimethylsiloxane, and the amount of inhibitor is 0.1% of the mass of hydroxyl-terminated polydimethylsiloxane.

[0031] Comparative Example 1 The example is basically identical to Example 1, with the only difference being that: the wax-modified silicone resin is not added in the release agent, but is replaced by the same amount of wax-silane blend obtained by blending polyethylene wax and hydroxyl-terminated polydimethylsiloxane at a mass ratio of 1:2.

[0032] Comparative Example 2 The embodiment 1 is basically identical, with the only difference being that the low-molecular-weight polyurethane is not added in the information layer coating, and the low-molecular-weight polyurethane is added on the high-acid-value acrylic resin.

[0033] Comparative Example 3 The embodiment 1 is basically identical, with the only difference being that the nano calcium carbonate is not added in the protective layer coating, and the nano calcium carbonate is added on the high-acid-value acrylic resin.

[0034] To prove that the flexographic cold stamping holographic security foil provided by the present application has good performance, the performance parameters of the flexographic cold stamping holographic security foil prepared in Examples 1-5 and Comparative Examples 1-3 are tested, including gloss, crack resistance, peeling force, and stamping effect in the cold stamping process, and whether there are white spot defects, and the test results are shown in Table 1.

[0035] The peeling force is tested by TMI, and the crack resistance is evaluated by a gold stamping machine.

[0036] Table 1 As can be seen from Table 1, the flexographic cold stamping holographic security foil provided by the embodiments of the present application has good crack resistance, excellent transfer effect, and few white spots compared with the comparative examples, which is prepared by adding wax-modified silicone resin, polyurethane-acrylic resin, and nano filler. However, Comparative Example 1 uses physical blending, and does not form a "wax-silicon" block structure, which prevents the wax chain from floating to form a super-smooth release surface, resulting in an increase in peeling force, easy peeling, incomplete peeling, and white spots. Comparative Example 2 does not add polyurethane, and the buffering effect of the information layer is poor, which cannot absorb the transfer stress well, resulting in easy cracking and white spots. Comparative Example 3 does not add nano calcium carbonate in the protective layer coating, which results in poor flexibility of the holographic security foil, and easy cracking.

[0037] The above only describes some embodiments of the present application. Those skilled in the art can make several modifications and improvements without departing from the inventive concept, and these all fall within the protection scope of the present application.

Claims

1. A low-migration defect soft-embossed cold-stamped holographic security foil, characterized in that, The base film layer, the release layer, the information layer, the reflection layer and the protective layer are sequentially stacked. The release layer, the information layer and the protective layer are sequentially coated with a release agent, an information layer paint and a protective layer paint, respectively, to form a coating layer, which is baked on a base film.

2. The low-migration defect soft-embossed cold-stamped holographic security foil according to claim 1, characterized in that, The release agent comprises the following components in parts by weight: wax-modified silicone resin 45-55 parts, composite resin 25-35 parts. The information layer paint comprises the following components in parts by weight: low molecular weight polyurethane 60-70 parts, high acid value acrylic resin 20-30 parts, nitrocellulose solution 10-15 parts, dye color paste 5-10 parts. The protective layer paint comprises the following components in parts by weight: high acid value acrylic resin 65-75 parts, fluorine-modified leveling agent 3-7 parts, nano calcium carbonate 10-20 parts.

3. The low-migration defect soft-embossed cold-stamped holographic security foil according to claim 2, characterized in that, The wax-modified silicone resin is prepared by the following steps: S1: adding microcrystalline wax and a crosslinking agent into a reaction kettle and reacting under inert gas protection to form a wax-silane block; S2: mixing hydroxyl-terminated polydimethylsiloxane, a platinum catalyst, an inhibitor and the wax-silane block, and filtering after adding a solvent to obtain the wax-modified silicone resin.

4. The low-migration defect soft-embossed cold-stamped holographic security foil according to claim 3, characterized in that, The crosslinking agent is selected from at least one of methyltrimethoxysilane, methyltriethoxysilane and tetraethoxysilane; the inhibitor is selected from at least one of ethynylcyclohexanol and diethyl maleate; and the solvent is selected from at least one of isopropyl alcohol, propylene glycol methyl ether acetate and methyl isobutyl ketone.

5. The low-migration defect soft-embossed cold-stamped holographic security foil according to claim 3, wherein, The mass ratio of the microcrystalline wax to the hydroxyl-terminated polydimethylsiloxane is 1:2-3; the amount of the crosslinking agent is 15-17% of the mass of the hydroxyl-terminated polydimethylsiloxane; the platinum catalyst has a pt concentration of 2000-2500 ppm, and the amount of the platinum catalyst is 0.5-1% of the mass of the hydroxyl-terminated polydimethylsiloxane; and the amount of the inhibitor is 0.1-0.2% of the mass of the hydroxyl-terminated polydimethylsiloxane.

6. The low-migration defect soft-embossed cold-stamped holographic security foil according to claim 3, wherein, In the S1 step, the temperature of the reaction kettle is 110-120℃, and the reaction time is 1.5-2 h; and in the S2 step, the mixing temperature is 120-140℃, the mixing time is 2-4 h, and the pore size of the filter core is 5-6 μm.

7. The low-migration defect soft-embossed cold-stamped holographic security foil according to claim 2, wherein, The composite resin is mixed from polyether type polyurethane, acrylic rubber, epoxy-modified acrylic resin and silicone-acrylic copolymer in a mass ratio of 6-7:2-3:1-2:0.5-1.

8. The low-migration defect soft-embossed cold-stamped holographic security foil according to claim 2, wherein, The weight average molecular weight of the low molecular weight polyurethane in the information layer paint is 5000-15000; the acid value of the high acid value acrylic resin in the information layer paint is ≥120 mg KOH / g; and the acid value of the high acid value acrylic resin in the protective layer paint is ≥150 mg KOH / g.

9. A process for the production of a low-migration defect-free flexo-cold stamping holographic security foil according to any one of claims 1 to 8, characterized in that, The method comprises the following steps: (1) according to the formula proportion, the wax modified silicone resin, the composite resin is stirred and mixed, the mixture is uniformly obtained, then the release agent is coated on the PET film, and the release layer is obtained after drying, and the coating dryness is 0.5~1g / m 2 ; (2) mixing low molecular weight polyurethane, high acid value acrylic resin according to the proportion, adding nitrocellulose solution, dye color paste, mixing uniformly to obtain information layer coating, then coating the information layer coating on the release layer of step (1), drying and then molding to obtain information layer, coating dry weight is 1~2g / m 2 ; (3) vacuum aluminum plating is performed on the information layer of step (2) to obtain a reflection layer; (4) high acid value acrylic resin, fluorine modified leveling agent according to the proportion of the formula is mixed uniformly, add nano calcium carbonate and mix uniformly, get the protective layer coating, then the protective layer coating is coated on the reflection layer of step (3), after drying get the protective layer, coating dryness is 1.5~3g / m 2 ; the low transfer defect flexographic cold stamping holographic anti-counterfeiting foil is obtained.

10. A process for the production of a low-migration defect-free flexographic cold stamping holographic security foil according to claim 9, characterized in that, In the step (1), the stirring temperature is 50-60 DEG C, and the stirring time is 30-40 min; in the step (2), the stirring temperature is 40-45 DEG C, and the stirring time is 40-50 min. In the step (1), the stirring temperature is 50-60 DEG C, and the stirring time is 30-40 min; in the step (2), the stirring temperature is 40-45 DEG C, and the stirring time is 40-50 min.

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