An embossed film for manufacturing an alignment film printing plate and a method for manufacturing the same

Abstract

The application discloses a kind of embossed film for alignment film printing plate manufacturing and preparation method thereof, embossed film includes from top to bottom sequentially arranged protective film layer, microstructure pattern layer, primer layer, PET base film layer, microstructure pattern layer is organic silicon coating and the micron level regular arrangement pattern formed by embossing on coating surface.Said preparation method comprises: polyvinyl alcohol cinnamate photoresist is coated on the surface treated PET base film, after exposure, development, film hardening, soft film with "flat roof platform dot" is prepared;Photocurable organic silicon resin is coated on the upper surface of PET base film layer, copy structure to organic silicon resin by flat roof platform dot mold, solidification, form microstructure pattern layer;Microstructure pattern layer surface covers a layer of protective film layer.The application solves the demoulding problem caused by embossed film coating material, and the technical problems such as low microstructure pattern processing precision, improves the processing precision and processing quality of alignment film printing plate.

Description

Technical Field

[0001] This invention relates to the field of liquid crystal display manufacturing materials technology. More specifically, this invention relates to an embossed film for manufacturing alignment film printing plates and a method for preparing the same. Background Technology

[0002] In liquid crystal display (LCD) manufacturing, to form a liquid crystal alignment film (polyimide film) of uniform thickness on the electrode formation surface of the glass substrate (TFT / CF) constituting the liquid crystal display element, a flexible printing method can be used, which allows for continuous production and produces a uniform ink film thickness. Flexible printing uses a flexible printing plate comprising a flat ink transfer layer containing a soft and elastic cross-linked resin. This ink transfer layer, with its surface loaded with ink that forms the basis of the liquid crystal alignment film, is in contact with the printed surface, such as the electrode formation surface. The plate surface is typically formed with a roughened surface of a specified roughness. The ink transfer layer with a roughened plate surface is manufactured using a photocurable resin, for example, that undergoes a curing reaction by irradiation with active light, through the following process.

[0003] Invention patents CN108454254 (Sumitomo Rubber Industries, Ltd.) and CN111221186 (Wuhan Ruipusai Technology Co., Ltd.) both describe a technology for creating an ink transfer layer for a printing plate using an embossing process. This process overcomes the defect of surface oxygen inhibition during the curing process of photosensitive liquid resin by covering the surface of the embossed film with an embossed film sheet. After curing, the embossed film sheet is peeled off from the surface of the flexible printing plate, thereby forming microstructure patterns with different regular arrangements on the surface of the printing plate, which is the ink transfer layer necessary for alignment liquid printing. This process avoids the defects of traditional film exposure plate-making technology in flexible printing plates, and by adjusting the size of the embossed film sheet, a flexible printing plate is integrally formed.

[0004] The photosensitive resin used to produce alignment film printing plates has low mechanical strength (tensile strength below 8 MPa, elastic modulus below 5 MPa). In the above printing plate process, the microstructure resin layer on the embossed film surface is obtained by curing methacrylate materials as the main adhesive. The acrylic material has a high surface energy, resulting in excessive demolding force during printing plate production, making it difficult to peel off the film, causing resin loss on the printing plate surface, forming a plate defect (judged as a defective product). Secondly, the regularly arranged microstructure patterns on the surface of this type of embossed film are transferred by a master wheel processed by nano / picosecond laser and CNC precision machine tool. The forming process of these ink transfer layer patterns not only has low processing accuracy, generally exceeding 3 μm (especially in the Z-axis direction), but also has high mold opening costs for the master wheel.

[0005] In order to comprehensively solve the demolding problem caused by the embossed film coating material and the low microstructure pattern processing precision and other technical problems, the applicant has carried out repeated in-depth research and developed the embossed film and the preparation method. SUMMARY

[0006] An object of the present application is to provide an embossed film for manufacturing an alignment film printing plate and a preparation method thereof, which solves the demolding problem caused by the embossed film coating material and the low microstructure pattern processing precision and other technical problems, and improves the processing precision and processing quality of the alignment film printing plate.

[0007] In order to solve the above technical problems, the present application provides an embossed film for manufacturing an alignment film printing plate, which comprises a protective film layer, a microstructure pattern layer, a primer layer and a PET base film layer arranged in sequence from top to bottom, wherein the microstructure pattern layer is a micron-level regular arrangement pattern formed by embossing the surface of an organic silicon coating.

[0008] Preferably, the protective film layer is made of polyethylene material and has a thickness of 20-50 μm; the microstructure pattern layer is formed by curing and molding of organic silicon resin and has a thickness of 30-100 μm; the primer layer is formed by coating of water-based polyurethane and has a thickness of 0.5-3 μm; and the PET base film layer has a thickness of 100-300 μm.

[0009] Preferably, the protective film layer has a thickness of 30 μm; the microstructure pattern layer has a thickness of 40-80 μm; and the PET base film layer has a thickness of 150-200 μm.

[0010] Preferably, the organic silicon resin contained in the microstructure pattern layer is made of the following raw materials in parts by weight: organic silicon acrylate prepolymer 50-90 parts, active diluent 0-30 parts, photoinitiator 1-5 parts, leveling agent 0.5-2 parts, and defoaming agent 0.1-1 part.

[0011] Preferably, the pattern on the microstructure pattern layer is formed into a regular pattern by printing a soft film with flat-topped convex net points on the upper surface of the embossed film, wherein the height of the circular convexes on the surface of the soft film is 5-30 μm, the diameter of the convexes is 5-50 μm, and the number of arrangement lines of the pattern on the microstructure pattern layer is 200-900.

[0012] Preferably, the height of the circular convexes on the surface of the soft film is 8-18 μm, and the number of arrangement lines of the pattern on the microstructure pattern layer is 400-800.

[0013] Preferably, the soft film is made of polyvinyl cinnamate negative photoresist and a soft sheet material thereunder, and the soft sheet material is a metal sheet or a high polymer film.

[0014] Preferably, the microstructure feature size on the microstructure pattern layer is accurate to within 3 μm.

[0015] The application also provides a preparation method of the embossed film for manufacturing an alignment film printing plate, comprising the following steps:

[0016] Step one, soft film preparation: using a slit coating method, polyvinyl cinnamate photoresist is coated on a surface-treated PET base film, then after exposure, development and film hardening, a soft film with "flat-topped boss dots" is prepared;

[0017] Step two, mixing and uniformly coating the photocuring silicone resin on the upper surface of the PET base film layer, copying the structure on the upper surface of the soft film through the flat-topped boss dot mold onto the silicone resin, then performing UV curing under a UV curing lamp to form a microstructure pattern layer, and winding after curing;

[0018] Step three, covering a protective film layer on the surface of the microstructure pattern layer after curing in step two by a composite roller.

[0019] Preferably, in step two, the PET base film layer is coated with a primer before being coated with the photocuring silicone resin, so that the photocuring silicone resin can easily adhere; in step one, the viscosity of the polyvinyl cinnamate photoresist is 1000-5000 mPa.s, and the exposure of the photoresist is achieved by active UV light through a mask plate, and the pattern line number on the mask plate is 200-900.

[0020] The application at least has the following beneficial effects:

[0021] 1. The microstructure pattern of the embossed film is realized by photolithography technology, and the photolithography technology and materials used in semiconductor manufacturing are adopted, so that the microstructure pattern processing precision of the embossed film surface is further improved to within 3 μm, and the processing precision and quality of the alignment film printing plate are improved.

[0022] 2. By changing the pattern (line number, diameter) on the photolithography mask plate (Fujifilm), the depth and apparent profile volume of the microstructure layer of the soft film (master film) can be controlled, that is, the master film with precise patterns is manufactured by photolithography means, the pattern arrangement can be adjusted according to the pattern design on the mask plate, and the apparent profile volume of the soft film surface is 3-15 μm 3 / μm 2 , and the depth is 5-20 μm, so that the ink liquid volume can be improved when transferred to the printing plate, and a printing plate with an ink transfer layer with different liquid volumes can be produced to meet the thick film printing demand.

[0023] 3、The present application uses silicone UV glue, by adjusting the coating thickness of the glue layer, while maintaining the optical transparency of the (meth) acrylate resin coating, also improves the surface finish of the film layer, avoids the film material defects such as pores and pinholes.

[0024] 4、The embossed film manufactured by the present application has a surface coating layer made of silicone material, which has a low surface energy and weak interaction with the printing plate resin, facilitating the post-forming film tearing (low demolding force).

[0025] 5、The present application provides a manufacturing method for further producing embossed films with lower cost and more diverse types than existing printing plates using the manufactured embossed film.

[0026] Other advantages, objects, and features of the present application will be apparent to those skilled in the art from the following description, and will be understood to be within the scope of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 A cross-sectional structure diagram of the embossed film provided by the present application;

[0028] Figure 2 A surface pattern diagram of the soft film used in the manufacture of the embossed film of the present application;

[0029] Figure 3 A manufacturing process diagram of the embossed film provided by the present application.

[0030] Explanation of reference signs:

[0031] 1, protective film layer, 2, microstructure pattern layer, 3, primer layer, 4, PET base film layer, 5, flat-top boss dot, 6, unwinding roller, 7, winding roller, 8, auxiliary roller, 9, guide roller, 10, soft film, 11, ultraviolet curing lamp. DETAILED DESCRIPTION

[0032] In order to better understand the purpose, structure and function of the present application, the present application will be further described in detail below in conjunction with the drawings, so that those skilled in the art can implement it according to the description.

[0033] It should be noted that the experimental methods described in the following embodiments are conventional methods, and the reagents and materials are commercially available unless otherwise specified. In the description of the present application, the terms "lateral", "longitudinal", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present application.

[0034] As shown in Figure 1 The present application provides an embossed film, from top to bottom, including a protective film layer 1, a microstructure pattern layer 2, a primer layer 3, and a PET base film layer 4. The microstructure pattern layer is an organic silicon coating and a micron-level regular arrangement pattern formed by embossing the surface of the coating.

[0035] The protective film layer is made of polyethylene (PE) material, with a thickness of 20-50 μm, preferably about 30 μm; the microstructure pattern layer is formed by curing an organic silicon photosensitive resin, with a thickness of 30-100 μm, preferably 40-80 μm; the PET primer layer is coated with water-based polyurethane, with a thickness of about 0.5-3 μm; and the PET base film layer has a thickness of about 100-300 μm, preferably 150-200 μm.

[0036] The main component of the organic silicon resin glue is organic silicon acrylate and its modified resin, which is prepared according to the following formula design (mass fraction):

[0037] Organic silicon acrylate prepolymer 50-90 parts,

[0038] Active diluent 10-30 parts,

[0039] Photoinitiator 1-5 parts,

[0040] Leveling agent 0.5-2 parts

[0041] Defoamer 0.1-1 part.

[0042] The pattern making process on the microstructure pattern layer requires the use of a soft film ("mother film") with flat-top boss dots 5, as shown in Figure 2As shown, the dot microstructure is transferred onto the surface of the embossed film to form a regular pattern. The height of the circular protrusions on the surface of the soft film is 5-30 μm, preferably 8-18 μm; the diameter of the protrusions is 5-50 μm, which can be precisely designed in conjunction with the number of lines in the pattern. The number of lines in the pattern on the microstructure pattern layer varies from 200 to 900. To meet the printing requirements of liquid crystal alignment films, a line count of 400-800 is preferred. The dimensional accuracy of the microstructure features does not exceed 3 μm.

[0043] The flexible film used in its manufacture is made of i-line polyethylene glycol cinnamate negative photoresist and its underlying flexible sheet. The flexible sheet can be a metal sheet, such as aluminum film or copper film; or it can be a polymer film, such as polyvinyl chloride, acrylic, polyester (PET, polyethylene terephthalate), polypropylene, etc.; considering the practicality of the technology, PET film is preferred.

[0044] The apparent profile volume of the prepared soft film surface is 3-15 μm. 3 / μm 2 The depth is 5-20μm.

[0045] The present invention also provides a method for preparing an embossed film for manufacturing alignment film printing plates, comprising the following steps:

[0046] (1) Fabrication of soft film: The polyvinyl alcohol cinnamate photoresist is coated onto the surface-treated PET base film by offline slit coating. After exposure, development and hardening, a soft film with "flat-top raised dots" is obtained.

[0047] (2) The photocurable silicone resin is mixed and uniformly coated on the upper surface of the PET base film layer online. The structure is then copied onto the silicone resin using a flat-topped dot mold on the upper surface of the soft film. UV curing is then performed under a UV curing lamp to form a microstructure pattern layer. After curing, the film is rolled up. Before coating the PET base film layer with the photocurable silicone resin, a base coating layer is first applied to facilitate the adhesion of the photocurable silicone resin.

[0048] The specific preparation process is as follows: Figure 3 The apparatus shown is now complete. Figure 3 The preparation apparatus includes unwinding rollers 6 and take-up rollers 7 on both sides, used for unwinding the PET base film layer before preparation and for winding the film with microstructured patterned layers after preparation, respectively. Between the unwinding and take-up rollers, multiple auxiliary rollers 8 are arranged to stretch the flexible film 10, and multiple guide rollers 9 are arranged below the auxiliary rollers. The PET base film layer passes sequentially between the unwinding roller, auxiliary rollers, guide rollers, and take-up roller, and is stretched taut. UV curing lamps 11 are also installed at corresponding positions on the auxiliary rollers and guide rollers for curing. Before the PET base film layer enters between the auxiliary rollers and guide rollers, it is coated with silicone gel.

[0049] (3) By the composite roller in the above step (2) after curing microstructure pattern layer surface composite a layer of PE protective film layer.

[0050] Step (1) polyvinyl cinnamate photoresist viscosity is 1000-5000 mPa.s, more preferably 2000-3000 mPa.s.

[0051] Step (1) of the photoresist exposure is achieved by active UV light through the mask, the mask pattern line number is 200-900, more preferably 400-800 lines.

[0052] The specific implementation of the complete process is described below.

[0053] Soft film production:

[0054] The thickness of 188 μm, 1.3 meters long, 0.8 meters wide PET film is laid on the exposure machine table, and the polyvinyl cinnamate photoresist (customized by Guangzhou Songda New Material, viscosity about 13000 cp) is uniformly coated on the PET film surface in the form of slit coating, the coating thickness is controlled at 100-120 μm, the upper glass substrate with film (ordered from Luwei Optoelectronics, 400-800 lines / inch) is lowered to the preset working position, and the exposure is 45 s (365 nm, 8 mW / cm 2 ); The mother film (soft film) after exposure is fixed on the cleaning machine by clamp, and the unhardened photoresist is cleaned by spraying developer, and then the developer is cleaned with pure water, dried and treated with 254 nm UV exposure for 5 min. The mother film surface "dot" arrangement is shown in Figure 2 .

[0055] Organic silicone resin glue preparation:

[0056] The microstructure layer of the embossed film of the present application adopts organic silicone light curing glue, which is compounded from commercially available resin. Considering the hardness, toughness and smoothness of the embossed film layer after curing, the inventors have selected several representative examples of organic silicone resin and its formula design several times. The formula data of several representative examples are shown in Table 1.

[0057] Table 1 Organic silicone resin glue formula of several embodiments of the present application

[0058]

[0059] The comparative example adopts acrylate glue (comparative example 1); the comparative example 2 is an embossed film material for mass production (the formula composition is unknown, but the main material is acrylate), and the related comparative example formula is shown in Table 2.

[0060] Table 2 Glue formula of several comparative examples of the present application

[0061]

[0062] The data of hardness, toughness, smoothness, etc. of the embossed film layer after curing of each of the above examples and comparative examples are shown in Table 3 below.

[0063] Table 3 Performance data of each example and comparative example

[0064]

[0065] Molding of the embossed film:

[0066] The molding process mainly includes two steps of film coating and molding curing: first, the silicone resin glue is coated on the surface of the PET substrate (i.e. PET base film layer) under the forward movement of the PET substrate; second, the master film with the "flat dot" microstructure is placed on the roller, and the microstructure is cured and molded on the surface of the film under the irradiation of the UV lamp on the PET substrate coated with the glue; after demolding, the target structure embossed film can be obtained (the process is as shown in Figure 3

[0067] Manufacture of the printing plate:

[0068] The manufacturing process of the flexible printing plate is referred to the patent CN103144458A, i.e. the embossed film in the examples and comparative examples is laid on the lower glass substrate of the exposure machine, a certain thickness of liquid photosensitive resin is coated, the other side is covered with a reinforced sheet material (PET material), and the photosensitive resin is exposed and cured by using the ultraviolet light (365 nm, irradiation intensity 5 mW / cm 2 ) through the embossed film sheet material, the printing plate is transferred after curing, and the embossed film sheet material is peeled off, so that the ink transfer layer with micron-level "concave-convex" structure is formed on the surface of the printing plate. According to the printing requirement, the printing plate is cut, laser engraved, cleaned, dried, etc.

[0069] Manufacture of the liquid crystal alignment film:

[0070] The flexible printing plate manufactured in the examples and comparative examples is combined with the anilox roller (unit volume is 6.5 cc / m 2 ) into the flexographic printing machine (A45 manufactured by Nakan, Japan) for printing the liquid crystal alignment film. Then, the ink for the liquid crystal alignment film (liquid crystal alignment agent manufactured by Dalton Technology Co., Ltd., Shenzhen, PI content 6 wt%) is supplied to the flexible printing plate, and the ink is printed on the soda lime glass substrate with ITO transparent electrode on the surface, and then pre-dried at 120°C for 30 minutes, so as to form the liquid crystal alignment film.

[0071] Thickness evaluation of the liquid crystal alignment film:

[0072] ​Samples were taken sequentially from the front and rear areas, left, middle and right of the printed glass substrate in the printing direction, and the samples were cut (cross-sections). The thickness of the PI alignment film was measured by scanning electron microscopy (SEM). Five thickness values ​​were measured for each group. The results were summarized and statistically analyzed to evaluate the thickness of the alignment film and the uniformity of the film thickness printed on the printing plate, as shown in Table 4 below.

[0073] Table 4 Evaluation of alignment film parameters for each embodiment and comparative example

[0074]

[0075] Among them, the surface profile volume Vvc (Core void volume) is a functional volume parameter of the 3D confocal profilometer. In this application, this parameter is used to make a quantitative judgment on the profile volume of the embossed film.

[0076] It is understood that the present invention has been described through some embodiments, and those skilled in the art will recognize that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the invention. Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. It can be applied to various fields suitable for the present invention, and other modifications can be easily implemented by those skilled in the art. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and examples shown and described herein.

Claims

1. An embossing film for manufacturing alignment film printing plates, characterized in that, It includes a protective film layer, a microstructure pattern layer, a base coating layer, and a PET base film layer arranged sequentially from top to bottom. The microstructure pattern layer is a regular micron-scale pattern formed by an organosilicon coating and embossing on the coating surface. The protective film layer is made of polyethylene with a thickness of 20-50 μm; the microstructure pattern layer is cured and molded from silicone resin with a thickness of 30-100 μm; the base coating layer is coated with water-based polyurethane with a thickness of 0.5-3 μm; the PET base film layer has a thickness of 100-300 μm; the silicone resin contained in the microstructure pattern layer includes the following raw materials in parts by weight: 50-90 parts silicone acrylate prepolymer, 0-30 parts reactive diluent, 1-5 parts photoinitiator, 0.5-2 parts leveling agent, and 0.1-1 parts defoamer; The pattern on the microstructure pattern layer is printed onto the surface of the embossed film using a soft film with flat-topped dotted dots to form a regular pattern. The height of the flat-topped dotted dots on the surface of the soft film is 5-30 μm, the diameter of the flat-topped dotted dots is 5-50 μm, and the number of lines in the pattern on the microstructure pattern layer is 200-900. The soft film is made of polyvinyl cinnamate negative photoresist and a soft sheet underneath, which can be a metal sheet or a polymer film.

2. The embossing film for manufacturing alignment film printing plates as described in claim 1, characterized in that, The protective film layer has a thickness of 30 μm; the microstructure pattern layer has a thickness of 40-80 μm; and the PET base film layer has a thickness of 150-200 μm.

3. The embossing film for manufacturing alignment film printing plates as described in claim 1, characterized in that, The height of the flat-top protrusions on the surface of the soft film is 8-18 μm; the number of pattern lines on the microstructure pattern layer is 400-800.

4. The embossing film for manufacturing alignment film printing plates as described in claim 1, characterized in that, The microstructure feature size accuracy on the microstructure pattern layer does not exceed 3μm.

5. The method for preparing an embossed film for manufacturing an alignment film printing plate as described in any one of claims 1 to 4, characterized in that, Includes the following steps: Step 1: Fabrication of the flexible film: Using a slot coating method, polyvinyl cinnamate negative photoresist is coated onto a surface-treated PET base film. After exposure, development, and hardening, a flexible film with "flat-topped raised dots" is obtained. Step 2: Mix the raw materials contained in the photocurable silicone resin and coat it evenly on the upper surface of the PET base film layer. Copy the flat-top protrusion dot structure on the upper surface of the soft film onto the silicone resin. Then, perform UV curing under a UV curing lamp to form a microstructure pattern layer. Step 3: Apply a protective film layer to the surface of the microstructure pattern layer cured in Step 2 using a composite roller.

6. The method for preparing an embossed film for manufacturing an alignment film printing plate as described in claim 5, characterized in that, In step two, before coating the PET base film with photocurable silicone resin, a base coating layer is first applied to facilitate the adhesion of the photocurable silicone resin. In step one, the viscosity of the polyethylene cinnamate photoresist is 1000-5000 mPa.s, and the exposure of the photoresist is achieved by active UV light passing through a mask. The number of lines on the mask pattern is 200-900.

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