Preparation method of UV plateless joint die pressing roller and die pressing process

Abstract

The application relates to a preparation method and a molding process of a UV plate-seam-free molding roller, and the method comprises the following steps: S1, preparing a micro-nano structure PET resin master plate, S2, preparing a 50um ultra-thin film mask, S3, preparing a primer plate roller and S4, preparing a micro-nano structure resin surface coating of the plate roller. Through the above process steps and the adoption of the 50um ultra-thin film mask, the UV plate-seam-free molding roller is improved in the micro-nano graphic production precision by reducing the scattering of the cured ultraviolet light, the UV plate-seam-free molding roller is applied to various molding processes such as hot molding, extrusion molding and UV molding, less than 0.1mm ultra-fine holographic graphic cycle seams are realized, micro-nano structure graphic cycle continuous film pressure is realized, the product does not generate plate seam lines and plate seam glue accumulation, and plate-seam-free molding production is realized.

Description

Technical Field

[0001] This invention belongs to the field of holographic molding technology, and particularly relates to a method for preparing a UV seamless molding roller and a molding process. Background Technology

[0002] Nanoimprint lithography is a novel micro-nano fabrication technology that achieves ultra-high resolution replication of micro-nano structures through mechanical transfer.

[0003] Currently, flatbed or roller embossing is generally used for replicating microstructures using nanoimprinting. Flatbed embossing is slow, inefficient, and cannot produce continuous microstructures. Roller embossing, on the other hand, typically uses a nickel master plate adhered to a roller for embossing. Although it is more efficient, it also cannot produce continuous microstructures. Furthermore, existing holographic nickel plates use a water-plating process, which involves the emission of heavy metals and acids / alkalis, causing environmental pollution and making it an environmentally harmful plate-making process.

[0004] Although there are devices that use two sets of printing rollers to repeatedly press and create hidden printing seams, there are still problems such as shadows formed at the printing seam due to temperature differences, reduced brightness caused by two printings, moiré interference patterns formed by two printings on some printing surfaces, or discontinuities in the pattern caused by errors in the two printings.

[0005] To address the issue of seam lines, patent documents such as CN105774192A, CN113978107A, and CN103448351A disclose methods for fabricating seamless UV holographic embossing plates on molding rollers. However, the applicant discovered that the seamless UV holographic embossing plate rollers in these patent documents have the following defects:

[0006] (1) There are defects in UV seam treatment: the traditional film mask is 100um thick. During curing, the ultraviolet light diffuses due to the thickness of the film mask itself, resulting in thicker seam lines, poor seam effect and low precision. DMD imaging precisely controls the scattering of ultraviolet light source and controls the exposure position. The alignment accuracy requirement is extremely high, the exposure efficiency is low, and the production difficulty is greatly increased.

[0007] (2) In the process of roller production, in order to ensure the firmness of the UV coating, the roller surface needs to be sanded, which has poor versatility and complex process flow; polyurethane coatings have poor anti-aging and pressure resistance properties and cannot meet the requirements of continuous and mass production. Summary of the Invention

[0008] To address the aforementioned problems in the prior art, this invention provides a method for preparing a UV seamless molding roller and a molding process.

[0009] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0010] In a first aspect, the present invention provides a method for preparing a UV seamless die roller, comprising:

[0011] S1. Preparation of micro-nano structured PET resin master: First, the nano-microstructure on the original plate is imprinted and replicated onto the PET base film using UV-curable coating. Then, the coating is fully cured and crystallized by UV irradiation to obtain a PET resin master with micro-nano patterns.

[0012] S2. Preparation of 50um ultrathin film mask: The graphic shape of the PET resin master obtained in S1 that needs to be cyclically docked is made into a light-shielding film with a thickness of no more than 50um. Then, the target on the PET resin master is aligned with the positioning mark of the light-shielding film and fixed.

[0013] S3. Preparation of base-coated printing roller: Based on the size of the micro-nano graphic loop docking in the PET resin master, a metal printing roller with matching circumference size is selected. This metal printing roller does not require surface roughening treatment. Then, under the condition that the ambient humidity does not exceed 60%, the metal printing roller is uniformly coated with base coating agent on the molding device using PET lead film, and then cured by ultraviolet light to obtain the base-coated printing roller.

[0014] S4. Preparation of the micro-nano structure resin topcoat of the printing roller: The PET resin master and the light-shielding film fixed together in step S2 are centered on the PET lead film, with the side of the PET resin master with micro-nano graphics facing upwards. The roller with the base coating prepared in step S3 is UV coated and molded, and UV curing is performed at the same time. The micro-nano graphics without film covering are prepared on the topcoat of the printing roller, and the cyclic docking is achieved to obtain a UV seamless printing roller.

[0015] The present invention discloses a method for preparing a UV seamless molding roller. Firstly, by combining the aforementioned process steps with the use of a 50µm ultra-thin film mask, the scattering of cured ultraviolet light is reduced, improving the precision of micro-nano graphic fabrication on the UV seamless molding roller. This UV seamless molding roller can be applied to various molding processes such as hot molding, extrusion molding, and UV molding, achieving ultra-fine holographic graphic loop seams of less than 0.1mm, realizing continuous cyclic molding of micro-nano structure graphics, and eliminating seam lines and glue buildup, thus achieving seamless molding production. Secondly, by using a performance-enhancing UV resin coating for surface coating, a micro-nano structure resin coating is created to replace the traditional nickel plate. The addition of nano-sized silica reduces the surface tension of the coating, improving aging resistance and pressure resistance, meeting the printing requirements of over 10,000 meters. Simultaneously, the UV resin coating can be repeatedly layered, improving the efficiency of UV resin roller production and enabling repeated cyclic production. Thirdly, the roller material and surface characteristics are not limited; ordinary steel rollers with a diameter of 50mm or more or mirror-plated chrome can be used, suitable for mirror or textured rollers.

[0016] Furthermore, following S4, there is also S5. UV seamless die roller surface treatment: After cleaning the UV seamless die roller obtained in S4, it is subjected to secondary UV curing to enhance the bonding strength between the metal die roller, the primer and the topcoat, and improve the surface strength of the topcoat.

[0017] Furthermore, the primer adhesive in S3 is composed of polyurethane acrylic resin, acrylic monomer, acylphosphine oxide, and p-hydroxyanisole, with a coating amount of 5 to 25 grams per square meter.

[0018] Furthermore, in S4, a precision pressure-adjusting molding device is used for UV surface coating molding. This molding device controls the UV coating thickness to 2-20 μm by controlling the pressure between the printing roller and the pressure roller according to the micro-nano structure depth requirements, and creates micro-nano structure patterns, achieving precise control of the overlap line to be less than 0.05 mm.

[0019] Furthermore, the UV coating in S4 is repeatedly molded and superimposed with micro-nano structure patterns to prepare a UV micro-nano coating, thereby improving the efficiency of UV seamless roller manufacturing and its reusability.

[0020] Furthermore, the thickness of the PET base film in S1 is ≥100μm.

[0021] Secondly, the present invention also provides a UV seamless molding process, which utilizes a UV seamless molding roller prepared by the above method.

[0022] For the various aspects of the second aspect mentioned above and the technical effects that each aspect may achieve, please refer to the above description of the technical effects that can be achieved for the first aspect or the various possible solutions in the first aspect, which will not be repeated here. Attached Figure Description

[0023] Figure 1 This is a schematic flowchart of the preparation method of the UV seamless die roller described in this invention;

[0024] Figure 2 This is a magnified view of a part of the product obtained by molding using the UV seamless molding roller described in this invention.

[0025] Figure 3 This is a magnified view of a part of the product obtained using existing molding processes. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0027] See Figure 1 , Figure 1 The present invention relates to a method for preparing a UV seamless die roller, comprising:

[0028] Step S1. Preparation of micro / nano-structured PET resin master: First, the nano-microstructures on the original master are imprinted onto the PET base film using a UV-curable coating. Then, the coating is fully cured and crystallized by UV irradiation, resulting in a PET resin master with micro / nano-textures. The thickness of the PET base film is ≥100μm to ensure that the substrate does not shrink or deform under UV irradiation, thus ensuring the accuracy of the micro / nano-textures. Substrates with a thickness less than 100μm are prone to shrinkage and deformation after UV irradiation, leading to positional shifts in the micro / nano-textures and substandard accuracy.

[0029] Step S2. Preparation of a 50µm ultrathin film mask: The graphic shape of the PET resin master obtained in S1, which requires cyclic docking, is made into a light-shielding film with a thickness of no more than 50µm. Then, the target on the PET resin master is aligned with the positioning mark on the light-shielding film and fixed in place. This light-shielding film is used to mask the excess micro-nano structure layer on the PET resin master during the UV curing process, according to the calculated circumference of the printing roller or the cycle period (the size of this micro-nano structure layer is larger than the blank size of the light-shielding film, so the excess micro-nano structure area can be masked by the light-shielding film), leaving only the required continuous microstructure on the metal printing roller.

[0030] Step S3. Preparation of the base-coated roller: Based on the size of the micro-nano graphic loop connection in the PET resin master, a metal roller with a matching circumference is selected. This metal roller does not require surface roughening treatment. Then, under ambient humidity not exceeding 60%, using a PET lead film, the metal roller is uniformly coated with a base coating agent on a molding device, and then cured by ultraviolet light to obtain the base-coated roller. The base coating agent is a UV resin varnish, composed of polyurethane acrylic resin, acrylic monomer, acylphosphine oxide, and p-hydroxyanisole (prepared by direct mixing and reaction), with a coating amount of 5–25 grams per square meter. The base coating agent, applied to the roller surface and cured by ultraviolet light, has a strong adhesion to the metal surface, playing a role in enhancing the bonding strength between the metal roller surface and the topcoat.

[0031] Step S4. Preparation of the micro-nano structure resin topcoat for the printing roller: The PET resin master and the light-shielding film, which were fixed together in step S2, are centered on the PET lead film, with the side of the PET resin master with the micro-nano pattern facing upwards. UV topcoat molding is then performed with the base-coated printing roller obtained in step S3, and UV curing is carried out simultaneously. This prepares the micro-nano pattern without film coverage onto the printing roller topcoat, achieving cyclic docking and obtaining a seamless UV-cured printing roller. The UV topcoat molding uses a performance-enhancing UV resin (this UV resin is an existing product, a mixture of polyurethane acrylic resin, acrylic monomer, and epoxy acrylic resin, such as UV-2910 or UV-2950 UV resin), and nano-sized silica (nano-silica dispersion) is added to this UV resin.

[0032] The method described in this invention, through the above-mentioned process steps and the use of a 50µm ultra-thin film mask, reduces the scattering of UV light during curing, thereby improving the micro-nano image fabrication accuracy of the UV seamless molding roller. Applying the UV seamless molding roller obtained above to various molding processes such as hot molding, extrusion molding, and UV molding achieves ultra-fine holographic image cyclic seams of less than 0.1mm, enabling continuous film pressing of micro-nano structure images. The product does not produce seam lines or adhesive buildup at seams, achieving seamless molding production. Compared with existing molding processes, the seam effect is better. Figure 2 A partially enlarged view of the UV seamless die-casting roller-molded product prepared using the method of the invention, and... Figure 3 The existing enlarged view shows a portion of the product molded using standard-sized pressure rollers. Furthermore, by employing a performance-enhancing UV resin coating for the topcoat, a micro-nano structured resin coating is created to replace the traditional nickel plate. The addition of nano-sized silica reduces the surface tension of the coating, improving its aging resistance and pressure resistance (see Table 1 below). This allows the topcoat to meet printing requirements exceeding 10,000 meters. Simultaneously, the UV resin coating can be repeatedly layered, improving the efficiency of UV resin roller production and enabling repetitive cycle production. Moreover, this method is not limited by the roller material or surface characteristics; ordinary steel rollers with a diameter of 50mm or more or mirror-plated chrome can be used, suitable for mirror or textured rollers.

[0033] Table 1 shows the test results of UV topcoat prepared by adding nano silica dispersion to UV-2950 UV resin.

[0034]

[0035] In one possible implementation, a precision pressure-adjusting molding device is used in S4 to perform UV surface coating molding. This molding device controls the UV coating thickness to 2-20 μm by controlling the pressure between the printing roller and the pressure roller according to the micro-nano structure depth requirements, thus creating micro-nano structure patterns and achieving fine control of the overlap line to be less than 0.05 mm.

[0036] See also Figure 1 The method for preparing the UV seamless die roller of the present invention further includes, after S4: S5. Surface treatment of the UV seamless die roller: After cleaning the UV seamless die roller obtained in S4, it is subjected to secondary UV curing to enhance the bonding strength between the metal die roller, the base coating and the top coating, and improve the surface strength of the top coating to meet the printing production requirements of more than 10,000 meters.

[0037] Of course, UV micro-nano coatings are repeatedly stacked in S4 to improve the efficiency of UV seamless roller manufacturing and reuse.

[0038] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A method for preparing a UV plateless slot die roll, characterized by, The method comprises the following steps: S1. Preparing a micro-nano structure PET resin master: first, imprint and copy the nano-micro structure on the original version on a PET base film by ultraviolet curing paint, and then irradiate by ultraviolet lamp to make the paint fully cured and the surface crystallized to obtain a PET resin master with micro-nano graphics; S2. Preparing a 50um ultra-thin film mask: the graphics shape required for the cycle docking of the PET resin master obtained in S1 is made into a light-shielding film with a thickness of not more than 50um, and then the target on the PET resin master is aligned and fixed with the light-shielding film positioning mark; S3. Preparing a primer version roller: according to the size of the micro-nano graphics cycle docking size of the PET resin master, a metal version roller with a matching version roller size is selected, which does not need to be surface roughened; then, under the condition that the environmental humidity is not more than 60%, the metal version roller is uniformly coated with a primer adhesive on a molding device by using PET film drawing, and then it is prepared by ultraviolet curing to obtain a primer version roller; S4. Preparing a version roller micro-nano structure resin surface coating: the PET resin master and the light-shielding film fixed together in step S2 are fixed in the middle on the PET film drawing, and the side surface of the PET resin master with micro-nano graphics faces upward, and UV surface coating molding is performed with the primer version roller prepared in step S3, and ultraviolet curing is performed at the same time, so that the micro-nano graphics without film covering are prepared on the surface coating of the version roller, the cycle docking is realized, and a UV seamless version molding roller is obtained.

2. The method of claim 1, wherein, After S4, S5. UV seamless version molding roller surface treatment is further included: after cleaning the UV seamless version molding roller prepared in S4, secondary ultraviolet curing is performed to enhance the bonding strength between the metal version roller, the primer and the surface coating, and to improve the surface strength of the surface coating.

3. The method according to claim 1 or 2, characterized in that, The primer adhesive in S3 is composed of polyurethane oleic ester resin, acrylic monomer, acyl phosphine oxide compound and p-hydroxyanisole, and the coating amount is 5-25 grams per square meter.

4. The method according to claim 1 or 2, characterized in that, In S4, a precision pressure molding device is used for UV surface coating molding. According to the depth requirement of the micro-nano structure, the pressure between the version roller and the pressure roller is controlled to control the UV coating thickness to be 2-20um, and the micro-nano structure pattern is made to realize fine control of the lap joint line to be less than 0.05mm.

5. The method of claim 4, wherein, In S4, the UV coating is molded multiple times, the micro-nano structure pattern is repeatedly superimposed, and the UV micro-nano coating is prepared to improve the efficiency and repeated use of the UV seamless version roller.

6. The method of claim 1 or 2, wherein, The thickness of the PET base film in S1 is >=100um.

7. A UV plateless slot die process characterized by, The UV seamless version molding roller prepared by any of the methods in claims 1-6 is applied.

Images