Printing sheet film covering method

Abstract

The invention discloses a printed sheet laminating method which comprises the following steps: arranging an image-text layer and a hot melt adhesive layer which are laminated on the surface of a base material layer in an online manner; an adhesive film layer is arranged on the surface of the hot melt adhesive layer; and heating and pressing are performed, so that the hot melt adhesive layer and the adhesive film layer are compounded together. According to the printed sheet laminating method, the image-text layer and the hot melt adhesive layer are arranged by the printing machine in an online manner, so that the influence of the hot melt adhesive layer on the color of the printed sheet is preposed, and the subsequent laminating operation basically does not influence the printing color. Therefore, an operator of a printing machine table can directly adopt the laminating sample provided by a client to check the printing color, and the risk that the color of a printed sheet and the color of the laminating sample of the client are within the allowable error range during printing but the color of the printed sheet and the color of the laminating sample of the client exceed the allowable error range after laminating is greatly reduced.

Description

Technical Field

[0001] This invention relates to the field of printing technology, and more particularly to a method for laminating printed sheets. Background Technology

[0002] In existing technologies, a significant portion of packaging boxes utilize lamination to protect the box itself. However, this lamination process presents a problem during printing: because the laminating adhesive layer is slightly yellowish, it affects the printed color after lamination. When using customer-provided lamination samples to verify printing colors, it frequently occurs that the printed color is within the acceptable error range compared to the customer's lamination sample during printing, but exceeds this range after lamination. Summary of the Invention

[0003] Therefore, it is necessary to provide a method for laminating printed sheets to solve the above problems.

[0004] A method for laminating printed sheets includes the following steps:

[0005] A layered graphic layer and a hot melt adhesive layer are fabricated on the surface of the substrate layer.

[0006] A film layer is formed on the surface of the hot melt adhesive layer;

[0007] Heating and applying pressure causes the hot melt adhesive layer to bond together with the adhesive film layer.

[0008] In one embodiment, the hot melt adhesive layer is made of water-based hot melt adhesive.

[0009] In one embodiment, the hot melt adhesive layer is obtained by anilox roller coating with a line count of 200 lpi to 400 lpi.

[0010] In one embodiment, the hot melt adhesive layer is calendered.

[0011] In one embodiment, the hot melt adhesive layer is provided with a recessed positive image.

[0012] In one embodiment, the adhesive film layer is made of PP, PET, or PVC.

[0013] In one embodiment, the thickness of the adhesive film layer is 8μm-20μm.

[0014] In one embodiment, the contact surface between the adhesive film layer and the hot melt adhesive layer is subjected to plasma treatment.

[0015] In one embodiment, the image layer is configured using any one of offset printing, gravure printing, flexographic printing, letterpress printing, or inkjet printing.

[0016] In one embodiment, the substrate layer is selected from any one of coated paper, white cardboard, grey cardboard, gold cardboard, and silver cardboard.

[0017] In the aforementioned sheet lamination method, because the image layer and hot melt adhesive layer are set up in tandem on the printing press, the influence of the hot melt adhesive layer on the sheet color occurs upfront. Subsequent lamination operations have virtually no impact on the printed color. Therefore, printing press operators can directly use the lamination sample provided by the customer to verify the printed color, thereby significantly reducing the risk that while the printed color may be within the acceptable error range compared to the customer's lamination sample color during printing, the color may exceed the acceptable error range after lamination. Attached Figure Description

[0018] Figure 1 This is a flowchart of a printing sheet lamination method according to one embodiment. Detailed Implementation

[0019] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0020] It should be noted that when an element is referred to as being "fixed to" another element, it can be directly attached to the other element or there may be an intervening element. When an element is considered to be "connected" or "connected" to another element, it can be directly connected to the other element or there may be an intervening element. The terms "upper," "lower," "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0021] The following section provides a more detailed explanation of the sheet lamination method in conjunction with the accompanying drawings and specific embodiments.

[0022] For a method of laminating printed sheets according to one embodiment, please refer to [link to relevant documentation]. Figure 1 The sheet lamination method includes the following steps:

[0023] Step S10: Online deposition of a graphic layer and a hot melt adhesive layer on the surface of the substrate layer.

[0024] The substrate layer serves as the packaging material and also supports the graphic layer and the hot melt adhesive layer.

[0025] Alternatively, materials that can be used as the substrate layer include, but are not limited to, coated paper, white cardboard, grey cardboard, gold cardboard, and silver cardboard.

[0026] The graphic layer is stacked on the surface of the substrate layer, serving both information carrying and decorative purposes.

[0027] Optionally, the image layer can be set in a manner including but not limited to offset printing, gravure printing, flexographic printing, letterpress printing, or inkjet printing.

[0028] The hot melt adhesive layer is stacked on the side of the graphic layer away from the substrate layer. The hot melt adhesive layer is obtained by the online setting of the printing press coating unit, so that after the printing process is completed, the substrate layer simultaneously contains the stacked graphic layer and the hot melt adhesive layer.

[0029] Optionally, the hot melt adhesive is a water-based hot melt adhesive, which is suitable for coating units of most printing presses and does not release VOCs during the drying process, thus having good environmental performance.

[0030] Optionally, the hot melt adhesive layer is obtained by an anilox roller with a line count of 200 LPI-400 LPI. By limiting the line count of the anilox roller, it can be ensured that the hot melt adhesive layer has a certain thickness after drying, thereby ensuring that the hot melt adhesive layer can be firmly attached to the adhesive film layer.

[0031] In another embodiment, the hot melt adhesive layer is calendered.

[0032] Specifically, the calendering equipment includes a calendering roller with a de-adhesive material on it. The roller also has a heating function, reaching the lower glass limit temperature of the hot melt adhesive, giving the hot melt adhesive layer a certain degree of elasticity. The calendering process creates a smooth outer surface for the hot melt adhesive layer, resulting in an optical reflection effect similar to that of the adhesive film layer, thus minimizing color errors caused by the adhesive film layer.

[0033] Optionally, the adhesive remover is silicone oil.

[0034] Preferably, the calender roller is provided with a raised negative image, the thickness of which is equal to the thickness of the hot melt adhesive layer. By providing the raised negative image, a recessed positive image can be generated on the hot melt adhesive layer. During the lamination process, since the air in the recessed positive image cannot be discharged in time, after the lamination is completed, anti-counterfeiting graphics formed by air bubbles will be generated in the recessed positive image area, thereby greatly enhancing the anti-counterfeiting effect of the product.

[0035] Preferably, the width of the negative image is 0.5-2mm. Under the action of lamination pressure, the local hot melt adhesive layers of the recessed positive image will be connected together, eventually forming an irregular and discontinuous cavitation effect similar to a candied hawthorn. The adhesive film layer above the cavitation part has a more obvious convex feel, thereby further enhancing the anti-counterfeiting effect.

[0036] Optionally, the calendering equipment and the printing equipment can be set up either online or offline.

[0037] In another embodiment, the hot melt adhesive layer is hollowed out. After step S20 of setting the adhesive film layer, the adhesive film layer in the non-adhesive position can be removed by die-cutting the adhesive film layer, thereby achieving a partial hollowing effect of the adhesive film layer, solving the problem that traditional lamination processes cannot achieve partial hollowing, and also increasing the anti-counterfeiting effect.

[0038] Step S20: Set an adhesive film layer on the surface of the hot melt adhesive layer.

[0039] A film layer is applied to the surface of the hot melt adhesive layer using the winding and unwinding devices of a laminating machine.

[0040] Optionally, the adhesive film layer can be made of PP film, PET film or PVC film.

[0041] Optionally, the thickness of the adhesive film layer is 8μm-20μm.

[0042] Preferably, the contact surface between the adhesive film layer and the hot melt adhesive layer is subjected to plasma treatment, which can significantly enhance the adhesion between the adhesive film layer and the hot melt adhesive layer.

[0043] Step S30: Heat and apply pressure to bond the hot melt adhesive layer with the adhesive film layer.

[0044] Specifically, the heating rollers of the laminating machine are used to heat and press the adhesive, causing the hot melt adhesive to melt and adhere tightly to the film layer, thus forming a laminating effect.

[0045] In the aforementioned sheet lamination method, because the image layer and hot melt adhesive layer are set up in tandem on the printing press, the influence of the hot melt adhesive layer on the sheet color occurs upfront. Subsequent lamination operations have virtually no impact on the printed color. Therefore, printing press operators can directly use the lamination sample provided by the customer to verify the printed color, thereby significantly reducing the risk that while the printed color may be within the acceptable error range compared to the customer's lamination sample color during printing, the color may exceed the acceptable error range after lamination.

[0046] Furthermore, the aforementioned sheet lamination method also has the following beneficial effects: During the application of water-based hot melt adhesive, the liquid water-based hot melt adhesive can fully wet and contact the surfaces of the image layer and the substrate layer. After curing, it eliminates the problem of microscopic "cavitation" that inevitably exists between the hot melt adhesive layer and the image layer in traditional lamination methods. Surprisingly, because there are no microscopic "cavitation" between the hot melt adhesive layer and the image layer, using the aforementioned sheet lamination method to laminate sheets with large ink areas can significantly improve the industry problem of easy blistering at the crease of laminated sheets with large ink areas.

[0047] The following are specific examples.

[0048] Example 1

[0049] Please see Figure 1 This embodiment provides a method for laminating printed sheets, including the following steps:

[0050] (1) An offset printing press with a coating unit is used to apply an image layer and a hot melt adhesive layer on the surface of the substrate layer in series. The hot melt adhesive layer is obtained by coating water-based hot melt adhesive with an anilox roller with a line count of 200 lpi.

[0051] (2) Use the unwinding and rewinding devices of the laminating machine to set an adhesive film layer on the surface of the hot melt adhesive layer.

[0052] (3) Use the heating roller of the laminating machine to heat and press, so that the hot melt adhesive layer and the film layer are tightly bonded together to form a laminating effect.

[0053] In the aforementioned sheet lamination method, because the image layer and hot melt adhesive layer are set up in tandem on the printing press, the influence of the hot melt adhesive layer on the sheet color occurs upfront. Subsequent lamination operations have virtually no impact on the printed color. Therefore, printing press operators can directly use the lamination sample provided by the customer to verify the printed color, thereby significantly reducing the risk that while the printed color may be within the acceptable error range compared to the customer's lamination sample color during printing, the color may exceed the acceptable error range after lamination.

[0054] Example 2

[0055] This embodiment provides a sheet lamination method, which is similar to the sheet lamination method provided in Embodiment 1, except that the hot melt adhesive layer in step (1) is calendered.

[0056] The above-mentioned sheet lamination method, through the calendering process of the calendering roller, can give the hot melt adhesive layer a smooth outer surface, thereby giving the outer surface of the hot melt adhesive layer an optical reflection effect similar to that of the adhesive film layer, thus minimizing the error caused by the adhesive film layer to color.

[0057] Example 3

[0058] This embodiment provides a sheet lamination method, which is similar to the sheet lamination method provided in Embodiment 2, except that: a recessed positive image is provided on the hot melt adhesive layer.

[0059] In the above-mentioned sheet lamination method, because the air inside the recessed positive image cannot be expelled in time during the lamination process, anti-counterfeiting graphics formed by air bubbles will be generated in the recessed positive image area after lamination is completed, thereby greatly enhancing the anti-counterfeiting effect of the product.

[0060] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for laminating printed sheets, characterized in that, Includes the following steps: A layered graphic layer and a hot melt adhesive layer are fabricated on the surface of the substrate layer. A film layer is formed on the surface of the hot melt adhesive layer; Heating and applying pressure causes the hot melt adhesive layer to bond together with the adhesive film layer.

2. The sheet lamination method according to claim 1, characterized in that, The hot melt adhesive layer is made of water-based hot melt adhesive.

3. The sheet lamination method according to claim 2, characterized in that, The hot melt adhesive layer is obtained by coating with an anilox roller with a line count of 200 lpi-400 lpi.

4. The sheet lamination method according to claim 3, characterized in that, The hot melt adhesive layer is calendered.

5. The sheet lamination method according to claim 4, characterized in that, The hot melt adhesive layer has a recessed positive pattern.

6. The method for laminating printed sheets according to any one of claims 1-5, characterized in that, The adhesive film layer is made of PP, PET or PVC.

7. The sheet lamination method according to claim 6, characterized in that, The thickness of the adhesive film layer is 8μm-20μm.

8. The sheet lamination method according to claim 7, characterized in that, The contact surface between the adhesive film layer and the hot melt adhesive layer is subjected to plasma treatment.

9. The sheet lamination method according to claim 8, characterized in that, The image layer can be set using any of the following methods: offset printing, gravure printing, flexographic printing, letterpress printing, or inkjet printing.

10. The sheet lamination method according to claim 1, characterized in that, The substrate layer is selected from any one of coated paper, white cardboard, grey cardboard, gold cardboard, and silver cardboard.

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