Transfer film for holographic printing

Abstract

The present invention provides a transfer film for holographic graphic printing, which has a layered structure consisting of a plastic base film layer [1], a release layer [2], and a transfer layer. The transfer layer is composed of transfer units arranged in a longitudinal and transverse manner. Each transfer unit contains a pattern used on a piece of board material for a package. The transfer layer has a holographic laser layer [4] and an aluminum plating layer [5]. The holographic laser layer has a laser effect pattern. The transfer layer also has a printed graphic layer [3]. The printed graphic layer has a blank space that is in a registration relationship with the laser effect pattern, and the registration deviation between the blank space and the laser effect pattern is ≤±10um. Since the release layer, printed graphic layer and holographic laser layer in the above-mentioned transfer layer are completed online in one go on the printing press, its high precision, integrated features and novelty, creativity and practicality have changed the defects of the existing iron printing process, such as multiple processes, difficulty in controlling the registration accuracy and high loss.

Description

Technical Field

[0001] This utility model relates to a transfer film for holographic graphic printing, which is a transfer film that can transfer printed patterns and laser effect patterns onto the surface of packaging materials such as tinplate, aluminum plate, and steel plate. Background Technology

[0002] Tinplate, or tinplate, is the primary material for manufacturing packaging for various food, beverage, and other products, including cans and boxes. As packaging, it's inevitable that various images and text will be printed on it. To achieve better graphic display and improve printing efficiency, the process of printing graphics on packaging sheets has undergone three stages of advancement. The first generation of tinplate printing involved directly coating and printing graphics onto the tinplate, but due to its lack of laser effect, inefficiency, and high cost, it is gradually being phased out. The second generation involved lamination and secondary transfer processes, but these lacked the ability to create holographic images and leave gaps, failing to meet the requirements for high quality and can welding. The third generation, laser film transfer followed by offset printing, while achieving a laser-like effect, still suffers from drawbacks such as multiple steps, potential registration errors, high waste, and high cost.

[0003] For example, the Chinese utility model patent "Coated Structure and Container with Positioning Laser Effect (202420574269.X)" discloses the aforementioned third-generation technology of first transferring laser film and then offset printing. This patent discloses the following steps for preparing a coated structure with positioning laser effect: 1. Coating a release layer: Applying a release coating to the base film to obtain a release layer. 2. Molding: Using existing positioning laser processes (such as heated molding or UV molding), a positioning laser holographic layer is obtained on the side of the release layer away from the base film, which has one or more laser effects, including cat's eye, embossing, dynamic graphics, 3D stereoscopic images, and microtext, set within the image. 3. Plating a reflective layer: Using a vacuum aluminum plating machine, an aluminum reflective layer is vacuum-deposited on the side of the positioning laser holographic information layer away from the release layer. 4. Dry lamination: Applying a dry lamination adhesive to the aluminum reflective layer side and laminating it with tinplate (metal layer). 5. Peel off the base film: Peel off the base film from the material obtained in step 4 to obtain tinplate with a positioning laser effect. Due to the presence of the release layer, the base film can be directly peeled off. 6. Print the graphics on the side of the tinplate with the positioning laser effect obtained above using offset printing on the side away from the release layer. 7. Apply tinplate varnish to the colored graphics to protect them. In other words, the third-generation process first obtains a transfer film with a holographic graphic layer, then transfers the holographic graphic onto the tinplate, then peels off the base film, and finally prints the graphic layer onto the release layer. This is a process commonly used in paper products. Usually, the precise alignment of the laser effect pattern on the holographic laser layer of the tinplate with the blank space on the printed graphic layer can only be achieved on tinplate cut into flat sheets. The edge of the flat sheet and color marks are used to achieve image alignment between the two printings in the second printing.

[0004] In summary, the aforementioned third-generation lamination with a positioning laser effect only has a holographic laser layer and lacks a printed image layer. After transferring the holographic image layer onto the roll-shaped sheet, the sheet must be cut into flat sheets before the image layer can be printed. This process requires seven steps, from applying the release agent to applying the printing varnish. The image printing takes place after the sheet with the holographic image layer has been cut into flat sheets. This operation inevitably leads to registration errors, and the numerous steps also result in higher waste and costs. Utility Model Content

[0005] To address the shortcomings of the existing technology, this utility model aims to provide a transfer film for holographic printing that can transfer a transfer unit containing overlapping printed graphic layers and holographic laser layers onto packaging material in a single roll.

[0006] This utility model provides a transfer film for holographic graphic printing, which is a roll of a long strip. The long strip has a layered structure composed of a plastic base film layer, a release layer, and a transfer layer. The transfer layer is composed of transfer units arranged longitudinally and laterally. Each transfer unit contains a pattern used on a piece of board material for a packaging item. The transfer layer has a holographic laser layer and an aluminum-plated layer. The holographic laser layer has a laser effect pattern. The transfer layer also has a printed graphic layer. That is, the long strip has a plastic base film layer, a release layer, a printed graphic layer, a holographic laser layer, and an aluminum-plated layer stacked in sequence. The printed graphic layer has blank spaces that are overprinted with the laser effect pattern, and the overprint deviation between the blank spaces and the laser effect pattern is ≤±10um.

[0007] The printed graphics and text referred to in this utility model refer to graphics and text printed using pigments, inks, or other coatings. Both the graphics and text and the patterns mentioned in this utility model include images and text, with graphics and text emphasizing pictures containing both images and text, while patterns emphasize the images and text themselves. The "layers" mentioned in this utility model, in terms of graphics and text, mainly refer to the order of printing. The "white space" mentioned in this utility model refers to the area where no coating is applied during the printing of graphics and text.

[0008] Packaging materials mainly consist of cans and boxes, which are usually not made from a single sheet of material. Some of these sheets require painting, while others do not. A transfer unit is the sheet of material that needs to be painted in order to make up a package. Therefore, each transfer unit contains the pattern used for one sheet of material in a package.

[0009] This utility model provides a transfer film for holographic image printing, which combines a holographic laser layer and a printed image layer. The laser effect pattern in the holographic laser layer and the blank space in the printed image layer are precisely overlaid, achieving a structure where the holographic laser layer and the printed image layer are integrally superimposed on a base film layer, forming a transfer film. This allows for the one-time transfer of the laser effect pattern and the printed image onto packaging materials, enabling can printing on roll materials. It not only eliminates the step of cutting the material into sheets for secondary printing but also makes the alignment of the holographic laser and the printed image more precise and convenient. Furthermore, using multi-color gravure and flexographic printing machines for image printing on roll film materials offers advantages over third-generation offset printing machines for metal sheets, including more colors, lower investment, and higher production efficiency. The price ratio of gravure, flexographic, and offset printing machines with the same number of colors is 1:1:10, and the efficiency ratio is 1:0.7:0.5.

[0010] The holographic transfer film for holographic graphic printing provided by this utility model is formed by first coating with ultraviolet curing varnish, then molding the laser effect pattern with a laser nickel plate, and finally curing with ultraviolet light. The laser effect pattern is molded on the side of the holographic laser layer facing the aluminum plating layer.

[0011] The holographic image printing transfer film provided by this utility model has a release layer that is a UV-cured release agent layer. That is, the release layer is formed by curing a UV release agent with ultraviolet light. Using a UV release agent not only provides good transparency but also makes the surface scratch-resistant and wear-resistant, eliminating the need for applying a printing varnish over the printed image layer, as in third-generation processes. At the same time, energy consumption is significantly reduced; the energy consumption of curing the release agent using an LED UV light source is 1:15 that of the third-generation process using a thermosetting release agent.

[0012] The holographic transfer film provided by this utility model has a decorative layer superimposed on the side of the holographic laser layer facing and / or away from the aluminum-plated layer. The decorative layer is a transparent or semi-transparent color and / or pattern.

[0013] In other words, a layer of transparent or semi-transparent ink is applied to the front, back, or both sides of the holographic laser effect pattern, or a pattern with a transparent or semi-transparent ink base is applied, or some patterns are printed on it. UV-curable varnish is a highly transparent material; regardless of which side is printed with color or pattern, the holographic effect pattern will appear colored, or have a colored base, or a pattern on the front.

[0014] The holographic image printing transfer film provided by this utility model also has an adhesive layer superimposed on the side of the aluminum-plated layer facing away from the holographic laser layer, and the adhesive of the adhesive layer is selected as hot melt adhesive or dry composite adhesive.

[0015] Hot melt adhesives can be pre-coated before the transfer film is manufactured and then wound into a roll. During lamination, preheating allows for direct lamination onto the metal sheet for transfer. Alternatively, the adhesive can be coated before transfer. Dry lamination adhesives cannot be pre-coated before the transfer film roll for holographic printing; they must be coated before lamination onto the metal sheet during transfer, followed by curing and film removal to achieve the desired transfer.

[0016] The holographic image printing transfer film provided by this utility model has overlapping and equal-width gaps between the release layer, transfer layer, and adhesive layer when the boundary of the corresponding packaging welding edge of the transfer unit is between two transfer units, and is connected by a plastic base film.

[0017] Some packaging materials, such as canned goods where leakage is not permitted, require welding. This means the transfer film will be used to print on materials that need to be welded. These materials have welding edges, and the transfer units used for them have edges corresponding to these welding edges. For example, the material used to make the cylindrical body of a can has a pair of welding edges, and the transfer units used for the can also have a pair of corresponding welding edges. The transfer units are arranged longitudinally and transversely on the base film. Sometimes, the edge corresponding to the welding edge may not be on the base film edge, and there may be two transfer units arranged adjacent to each other with this edge. In this case, there is a gap between adjacent transfer units. This gap means that there is no other material besides the plastic base film, ensuring that no impurities adhere to the metal sheet after the transfer. This gap is ≥2mm wide, and after cutting, each side has a blank space of at least 1mm to facilitate welding.

[0018] There are two ways to create gaps in the transfer film during the transfer process. One is that when the boundary of the corresponding packaging welding edge of the transfer unit is between two transfer units, the release layer, transfer layer, and adhesive layer have overlapping gaps of equal width, connected by a plastic base film. The other is that when the boundary of the corresponding packaging welding edge of the transfer unit is between two transfer units, the adhesive layer has gaps, connected by a plastic base film.

[0019] The former leaves gaps in the printed graphic layer, holographic laser layer, aluminum plating layer, adhesive layer, and release layer. Besides localized printing of these layers, it also requires aluminum removal from the aluminum plating layer. The latter, however, only leaves gaps in the adhesive layer. Relying on the adhesive's stickiness and the adhesion of the transfer layer to the plastic base film, the printed graphic layer, holographic laser layer, aluminum plating layer, and release layer are removed during the transfer process.

[0020] The holographic image printing transfer film provided by this utility model uses a combination of cursor tracking and positioning technology and localized adhesive transfer technology to apply the adhesive locally to the pattern area of ​​the transfer unit. When the plastic base film layer is peeled off, the unadhesive portion remains on the base film layer, leaving the packaging material blank (no transfer), thus achieving the purpose of leaving a void. Typically, the overlap error between the adhesive coating surface and the boundary of the transfer unit on the blank side is ≤0.3mm.

[0021] The holographic image printing transfer film provided by this utility model completes the coating of the release layer, the printing of the image layer and the holographic laser molding process in one step on a printing machine equipped with a UV molding device. After aluminum plating, the adhesive is applied by positioning, so as to transfer the stacked release layer, the printing of the image layer, the holographic laser layer, the aluminum plating layer and the adhesive layer to the packaging material in one step and meet the requirements for leaving gaps. This fundamentally solves the shortcomings of the third-generation process. Attached Figure Description

[0022] Figure 1 This is a partial view of an embodiment of the present invention. In the view: 1-plastic base film layer, 2-release layer, 3-printed graphic layer, 4-holographic laser layer, 5-aluminum plating layer, 6-adhesive layer.

[0023] Figure 2 yes Figure 1 A cross-sectional view along the length direction, in which: 1-plastic base film layer, 2-release layer, 3-printed graphic layer, 4-holographic laser layer, 5-aluminum plating layer, 6-adhesive layer, 7-blank space, 8-blank space, A-transfer unit. Detailed Implementation

[0024] 1. For example Figure 1 , 2 As shown, a roll of holographic image printing transfer film is formed by sequentially stacking a plastic base film layer 1, a release layer 2, a printed image layer 3, a holographic laser layer 4, an aluminum-plated layer 5, and an adhesive layer 6. The printed image layer has blank spaces 7, and the holographic laser layer has a laser effect pattern. When the release layer 2, printed image layer 3, and holographic laser layer 4 are stacked, the laser effect pattern and the blank spaces are overprinted, with an overprinting error accuracy within ±10µm. After the printed image layer 3 and the holographic laser layer 4 are superimposed on the transfer film, a complete pattern formed by the printed image and the laser effect pattern represents a transfer unit A. One transfer unit is used for transferring the image onto a single sheet of material in a package. A roll of transfer film is composed of numerous transfer units arranged continuously in a longitudinal and transverse pattern on the plastic base film.

[0025] After the release layer 2, printed graphic layer 3, and holographic laser layer 4 are stacked and then aluminum-plated, adhesive is applied to the coating machine with secondary tracking and positioning functions. The adhesive layer 6 uses hot melt adhesive. The adhesive is applied to the area occupied by the transfer unit, and the overlap accuracy between the adhesive coating surface and the transfer unit is ±30um.

[0026] The release layer is formed by UV release agent and UV curing, serving both as a release agent and as a final protective layer for the printed graphic surface. The holographic laser layer is formed by applying UV-curable varnish, molding a laser effect pattern onto a laser nickel plate, and then curing with UV light, wherein the laser effect pattern is molded onto the side of the holographic laser layer facing the aluminum plating layer.

[0027] 2. The three-piece metal can body needs to be welded. For smooth and strong welding, there must be no foreign objects at the weld edges. For the transfer film roll used for the three-piece metal can, each transfer unit has an 8mm gap on its side. Figure 2 As shown, the release layer 2, printed graphic layer 3, holographic laser layer 4, aluminum plating layer 5, and adhesive layer 6 are all missing in the blank area, connected only by the plastic base film layer 1. The width of this blank is ≥2mm.

[0028] In the example above, when applying hot melt adhesive to the transfer film roll for positioning, a gap should be left at the designated area, with a gap width ≥ 2mm. The overlap error between the hot melt adhesive and the gap should be ≤ 0.3mm.

[0029] 3. A holographic printing transfer film. Its laser effect pattern not only overlaps with the printed text and images but also with the decorative layer; that is, there are overlapping printed layers on one or both sides of the laser effect pattern. The decorative layer is used to enhance the decoration or better represent the laser effect, such as maximizing the three-dimensional depth of field and landscape effect of a cat's-eye lens. The decorative layer is a color pattern other than the UV varnish layer that constitutes the laser effect pattern, which both displays the laser effect. This can be a transparent or semi-transparent monochrome or polychrome color, a transparent or semi-transparent color as a background for printing text and images, or a mostly blank background for printing text and images.

[0030] 4. For example Figure 1 , 2 The preparation steps of the holographic printing transfer film shown are as follows:

[0031] 1. Apply a UV release agent to the long strip of plastic base film 1 of the first color group of the printing unit and dry it to obtain the release layer 2.

[0032] 2. In the second, third, ... color groups of the printing press, the printing pattern is overprinted on the release layer according to the design requirements to obtain the printed graphic layer 3. The decorative layer of the laser effect pattern is then overprinted onto the blank spaces 7 that are overprinted with the laser effect pattern. Simultaneously, one pattern corresponds to one transfer unit for can transfer. The transfer units are arranged continuously along the length of the long strip of plastic base film, with a gap 8 of ≥2mm between every two transfer patterns.

[0033] III. The tenth color group of the printing press exist A UV-curable varnish is applied to a pre-printed graphic layer, which is then molded into a laser nickel plate mold and cured with ultraviolet light to obtain a holographic laser layer 4 that carries a UV laser effect pattern. The laser effect pattern is overprinted with the pattern on the printed graphic layer. The UV-curable varnish can be applied to the entire transfer unit, or applied to a portion of the unit, or overprinted with a blank area.

[0034] 4. After printing the laser effect pattern, the printing unit pattern formed by superimposing the printed graphic layer and the holographic laser layer of the transfer film obtained in the previous step is coated with aluminum in the vacuum aluminum plating unit to obtain the reflective aluminum plating layer 5.

[0035] 5. Finally, the transfer film obtained in the previous step is partially coated with hot melt adhesive to obtain adhesive layer 6. Partial coating of hot melt adhesive means that it is not applied to the entire width of the transfer film, but only to the transfer pattern. The overlap error between the boundary of the hot melt adhesive coating area and the boundary of the transfer pattern is ≤0.3mm.

[0036] The holographic printing transfer film transfer process using hot melt adhesive coating is as follows: heating → bonding the transfer film to tinplate with adhesive → removing the base film → cutting → can making.

[0037] 5. A holographic printing transfer film, which is made of dry composite adhesive, wherein the dry composite adhesive is applied in a positioning position before the transfer to obtain an adhesive layer with gaps, and then it is laminated with a metal plate. After the transfer, the plastic base film is peeled off, and the release layer, holographic laser layer, aluminum plating layer and base film at the gap of the adhesive are removed, resulting in a gap ≥2mm wide.

[0038] The process of holographic printing transfer film using dry composite adhesive is as follows: positioning and coating the adhesive → bonding the transfer film to tinplate with adhesive → removing the base film → cutting → can making.

[0039] 6. A holographic printing transfer film, formed by stacking a plastic base film layer, a release layer, a printed image layer, a holographic laser layer, and an aluminum-plated layer, with no gaps in any layer. Before transfer, hot melt adhesive is applied to specific locations to obtain an adhesive layer with gaps. After transfer, the plastic base film layer is peeled off, and the release layer, printed image layer, holographic laser layer, and aluminum-plated layer at the gaps in the adhesive layer are all removed along with the base film, resulting in a 2mm wide gap.

Claims

1. A transfer film for holographic image printing, comprising a roll of a long strip, the roll having a layered structure consisting of a plastic base film layer, a release layer, and a transfer layer, wherein the transfer layer is composed of transfer units arranged longitudinally and transversely, each transfer unit containing a pattern used on a sheet of material for a packaging item, the transfer layer having a holographic laser layer and an aluminum-plated layer, the holographic laser layer having a laser-effect pattern, characterized in that... The transfer layer also includes a printed graphic layer, that is, the strip has a plastic base film layer, a release layer, a printed graphic layer, a holographic laser layer, and an aluminum plating layer stacked in sequence. The printed graphic layer has blank spaces that are overprinted with the laser effect pattern, and the overprinting deviation between the blank spaces and the laser effect pattern is ≤±10um.

2. The transfer film for holographic image printing as described in claim 1, characterized in that... The holographic laser layer is formed by first coating with ultraviolet curing varnish, then molding the laser effect pattern with a laser nickel plate, and finally curing with ultraviolet light. The laser effect pattern is molded on the side of the holographic laser layer facing the aluminum plating layer.

3. The transfer film for holographic image printing as described in claim 2, characterized in that... A decorative layer is superimposed on the side of the holographic laser layer facing and / or away from the aluminum-plated layer. The decorative layer is a transparent or semi-transparent color and / or pattern.

4. The transfer film for holographic image printing as described in claim 3, characterized in that... The release layer is a UV-cured release agent layer.

5. The transfer film for holographic image printing as described in claim 1, 2, 3, or 4, characterized in that: An adhesive layer is also superimposed on the side of the aluminum-plated layer facing away from the holographic laser layer, and the adhesive used in the adhesive layer is a hot melt adhesive or a dry composite adhesive.

6. The transfer film for holographic image printing as described in claim 5, characterized in that... When the boundary of the corresponding packaging welding edge of the transfer unit is between two transfer units, the release layer, transfer layer, and adhesive layer have overlapping and equal-width gaps, and are connected by a plastic base film.

7. The transfer film for holographic image printing as described in claim 6, characterized in that... The blank space is a long strip with a width of ≥2mm.

8. The transfer film for holographic image printing as described in claim 5, characterized in that... When the boundary of the corresponding packaging welding edge of the transfer unit is between two transfer units, the adhesive layer has a gap and is connected by a plastic base film.

9. The transfer film for holographic image printing as described in claim 8, characterized in that... The overlap error between the adhesive layer gap and the transfer unit is ≤0.3mm.

10. The transfer film for holographic image printing as described in claim 8, characterized in that... The blank space is a long strip with a width of ≥2mm.

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