A production process for a high whiteness and brightness film

Abstract

The present invention provides a production process for high-whiteness and high-brightness films. V-shaped concave lines arranged in parallel are lithographically produced on a nickel plate, and then the nickel plate is attached to the surface of a cylindrical plate roller to form a brightening plate roller; a transparent coating with a surface tension greater than 42 dynes is coated on the base film; a blue UV coating obtained by uniformly stirring a UV coating and a blue dye is coated on the transparent coating, and pre-cured under the irradiation of ultraviolet light. When the coating is not completely cured, the V-shaped concave lines of the brightening plate roller are transferred to the UV adhesive layer by rolling with the brightening plate roller to form protruding prism lines, and then cured by ultraviolet light. By forming a light blue UV coating and prism protruding lines with appropriate spacing on the film surface, the brightness and whiteness of the film are improved.

Description

Technical Field

[0001] The present invention relates to a manufacturing method of plastic films, specifically a production process capable of improving the whiteness and brightness of plastic films. Background Art

[0002] The widely used high-whiteness and high-brightness films are made by high-temperature evaporation of zinc sulfide on base films such as polyester (PET) or biaxially oriented polypropylene (BOPP), followed by coating and coloring, and multi-layer lamination. The glitter powder processed from such films not only has a three-dimensional effect and can enhance the visual effect of products, but also its highly shiny characteristics make the decorations bright and eye-catching, adding luster. Therefore, it is widely used in fields such as Christmas crafts and cosmetics. However, the manufacturing process of this high-whiteness and high-brightness film is complex, the production cost is relatively high, the controllability of zinc sulfide evaporation is poor, and there are easily defects such as uneven and rough coatings.

[0003] CN102176082A discloses a production method of a reflective film with a micro-prism array structure, which uses an annular mold that reciprocates along a closed loop, and its outer surface has a continuous micro-prism array structure in a concave shape. A layer of hot-melt resin is coated on one surface of the resin film, and then the resin film, the hot-melt resin, and the annular mold are synchronously molded, and then the resin film coated with the hot-melt resin and the annular mold are synchronously cooled, so that the micro-prism array structure on the resin film coated with the hot-melt resin and the hot-melt resin layer together form a laminated film. However, the micro-prism density of its product is too large, the light interference is relatively serious, and the colorful colors are obvious. Therefore, it is only used as a colorful reflective film and does not have the property of whitening. The reflective film is prone to dust accumulation or foreign matter pollution, and it is necessary to protect the prism surface by means such as evaporation coating. Due to the synchronous cooling of the film and the annular mold, the production efficiency is low.

[0004] CN103192554A discloses a manufacturing method of a micro-prism reflective film. The surface of the substrate is subjected to corona treatment, and the UV resin is made into micro-prism pyramids, and the bottom surface of the micro-prism pyramids is fixed on the surface of the substrate by means of light-curing and rapid drying. However, the micro-prism density of its product is too large, the light interference is relatively serious, and the colorful colors are obvious. Therefore, it is only used for colorful reflective films and does not have the property of whitening. Due to the timeliness of the corona effect, the bonding force between the UV material and PET will gradually decay, resulting in local peeling and delamination, that is, the blistering phenomenon.

[0005] CN105372733A discloses a reflective film with a moth-eye structure and its preparation process. The reflective film includes a PET layer, a reflective structure layer, and a moth-eye antireflection structure layer. The reflective structure layer uses a pyramid structure with three mutually perpendicular sides as the reflective structure based on the principle of geometric optics. The moth-eye antireflection structure layer uses a moth-eye-like micro-nano structure as the antireflection layer based on the principle of bionics. Its product has an excessive microprism density, serious light interference, and obvious colorful colors. Therefore, it is only used for colorful reflective films and does not have the performance of whitening. The structure of the reflective film is complex and the production efficiency is low. Summary of the Invention

[0006] The purpose of the present invention is to provide a production process for a high-whiteness and high-brightness film, which improves the brightness and whiteness of the film by forming a light blue UV coating and prism protruding lines with appropriate spacing on the film surface.

[0007] The production process for the high-whiteness and high-brightness film of the present invention includes the following steps:

[0008] A. Photolithographically make parallel V-shaped concave lines with a width of 10 - 20 μm, a depth of 0.5 - 1 times the width, and a distance of 2 - 4 times the width on a nickel plate, and then attach the nickel plate to the surface of a cylindrical plate roller to form a brightness-enhancing plate roller;

[0009] B. Preparation of UV coating: Mix and stir evenly UV coating and blue dye in a weight ratio of 100:(5 - 20) to obtain blue UV coating;

[0010] C. Coat a transparent coating with a surface tension greater than 42 dynes on the base film;

[0011] D. Coat the blue UV coating on the transparent coating of the base film, pre-cure it under ultraviolet light irradiation. When the coating is not completely cured, roll it with the brightness-enhancing plate roller so that the V-shaped concave lines of the brightness-enhancing plate roller are transferred to the UV adhesive layer to form protruding prism lines, and then cure it with ultraviolet light to become a high-whiteness and high-brightness film.

[0012] Preferably, in step A, the depth of the V-shaped concave lines is 0.6 - 0.7 times the width, and the distance is 2.5 - 3.5 times the width.

[0013] Preferably, in step B, the weight ratio of the UV coating to the blue dye is 100:(10 - 15).

[0014] Preferably, in step C, the base film is a polyester film or a biaxially oriented polypropylene film; the thickness of the transparent coating is 0.5 - 20 μm; the transparent coating is an aqueous acrylic emulsion coating, and the coating amount after drying is 0.7 - 0.9 g / M 2 , or the transparent coating is an adhesive layer with a thickness of 0.3 - 20 μm.

[0015] Preferably, in step D, before the blue UV coating is applied to the base film, it is preheated at 50 ± 2 °C.

[0016] In the present invention, by forming a light blue UV coating and prismatic convex lines on the surface of the film, by reducing the density of the prismatic lines and the light blue coating, the light reflection effect on the film surface is improved and the light interference effect is reduced. Therefore, when observing the film surface from a wide angle, a white rather than a multicolored visual effect can be shown. Through the high surface tension transparent coating on the base film, it is beneficial to form a light reflection interface with the upper UV coating to improve the light reflection effect, making the white and brightness effects of the film more prominent, and the product can be stored for a long time without delamination and peeling. The film can form prismatic convex lines by rolling, with high efficiency and low manufacturing cost. It can be further made into various required films or glitter powders through further coating, coloring, multi-layer compounding, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a partial sectional view of the brightening master.

[0018] Figure 2 It is a schematic diagram of the film coating structure. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0019] Example 1

[0020] In this example, a commercial pre-coated film is used as the substrate for UV coating processing. The product process route is: pre-coated film - UV layer coating - UV embossing - slitting - packaging.

[0021] Take a metal nickel plate with a length and width of 100 × 100 mm and a thickness deviation not exceeding 1.5 μm, and use photolithography to make parallel concave lines 1 with a V-shaped cross-section ( Figure 1 as shown), the width a above the concave part is 15 μm, the depth h is 10 μm, the platform width b between the concave lines is 50 μm, and the overall layout is required to be clean without defects such as pinholes, to become a small unit brightening master.

[0022] Attach several small unit brightening masters tightly to a substrate and splice them into an embossing working plate. The thickness of the embossing working plate is controlled at about 50 μm, cut the plate according to the product specifications and equipment parameters to calculate the required length and width of the embossing working plate, and attach it to the surface of a matching cylindrical plate roller to form a brightening template.

[0023] Pre-coated film selection: Use a commercially available pre-coated film, which consists of a polyester (PET) substrate and an adhesive layer. The thickness of the PET film is 22 - 24 μm, the thickness of the adhesive layer is 0.3 - 0.5 μm, and the surface tension of the coating is about 52 dynes. The commercial use of this pre-coated film is to compound with paper prints to improve the gloss and fastness of the prints, and play roles such as waterproof, anti-fouling, wear-resistant, fold-resistant, and chemical corrosion-resistant.

[0024] Preparation of UV coating: The UV coating of model B-5 produced by Shantou Dongfeng Printing Co., Ltd. and the Victoria blue dye produced by Fujian Kuncai Materials Technology Co., Ltd. are formulated into a blue slurry according to a weight ratio of 100:5, stirred on an automatic stirrer for more than 2 hours, and then the above-mentioned UV coating and the above-mentioned blue slurry are mixed according to a weight ratio of 100:6, and stirred at a constant temperature of 50 °C for 1 hour to obtain a blue UV coating for machine use. The viscosity of the blue UV coating for machine use is 65-85 centipoise.

[0025] The blue UV coating for machine use is roll-coated on the adhesive layer of the pre-coated film through an intaglio roller. The coating roller is a diamond honeycomb intaglio, and the depth of the roller cells is about 50 μm and the width is about 45 μm.

[0026] The pre-coated film coated with the blue UV coating is pre-cured by ultraviolet light irradiation. The power of the ultraviolet lamp for pre-curing is 12 KW. The PET film coated with the blue UV coating is dried at 50-60 °C and irradiated by the ultraviolet lamp at a speed of 40-60 m / min. When there are still fingerprints on the surface of the coating when pressed with fingers and it is in an incompletely cured state, the cold transfer printing technology is adopted, and the PET film coated with the blue UV coating is rolled by a brightening roller. The rolling pressure of the brightening roller is 0.33 MPa, and the brightening roller is cooled by circulating cooling water at 20±2 °C. The rolled film is further cured by ultraviolet light irradiation, slit, and packaged into a film product.

[0027] The structure of the manufactured product is as Figure 2 shown, including a base film 1, a transparent coating 2 above the base film 1, and a UV coating 3 on the transparent coating 2. There are raised prism lines on the UV coating 3. The prism surface and the plane between the prisms become reflective surfaces, showing relatively high whiteness and brightness. When observing the film within a relatively large angle range from the film surface, since there is sufficient distance between the reflected light of the prisms and adjacent prisms, no light interference phenomenon occurs, so no colorful visual effect after light interference appears.

[0028] The sample is placed on an A4 paper and measured with an X-Rite colorimeter Ci6X. The L* value is 101.66, the a* value is -0.06, and the b* value is -0.05. The measured values of the used A4 paper are: L* value 90.85, a* value 1.07, b* value -6.28. The large changes in the L* value, a* value, and b* value indicate that the product has relatively high brightness and whiteness. The product is subjected to a natural sunlight exposure aging test for 24 months, and no blistering phenomenon is observed, indicating that no peeling occurs between the composite layers.

[0029] Example 2

[0030] In this embodiment, a polyester (PET) film is used as the substrate, and the product process route is: PET base film - bottom coating - UV layer coating - UV embossing - slitting - packaging.

[0031] Take a nickel metal sheet with a length and width of 100×100 mm and a thickness deviation not exceeding 1.5 μm. Use photolithography to make parallel concave lines with a V-shaped cross-section. The width a above the concave part is 15 μm, the depth h is 10 μm, and the platform width b between the concave lines is 45 μm ( Figure 1 as shown). The overall layout is required to be clean without defects such as pinholes, etc., to become a small unit brightening master.

[0032] Attach several small unit brightening masters tightly to a substrate and piece them together to form an embossing working plate. The thickness of the embossing working plate is controlled at about 50 μm. Cut the plate according to the length and width required for the embossing working plate calculated based on the product specifications and equipment parameters, and attach it to the surface of a matching cylindrical plate roller to form a brightening plate roller.

[0033] Coat a layer of waterborne acrylic emulsion paint on the polyester (PET) film. The diluent is alcohol and deionized water, the solid content is 20 wt%, the paint viscosity is 10 - 40 centipoise, and the wet coating amount is controlled at 3.5 - 4.5 g / M 2 , the drying temperature is controlled at 90 - 120 °C, the production speed is 100 m / min, the thickness of the dried coating is about 0.8 μm, and the surface tension of the coating is about 45 dynes.

[0034] Preparation of UV paint: Mix the UV paint of model B-5 produced by Shantou Dongfeng Printing Co., Ltd. and the Victoria blue dye produced by Fujian Kuncai Materials Technology Co., Ltd. in a weight ratio of 100:5 to form a blue slurry, and stir on an automatic stirrer for more than 2 hours; then mix the above UV paint and the above blue slurry in a weight ratio of 100:6 and stir at a constant temperature of 50 °C for 1 hour to become the blue UV paint for machine use. The viscosity of the blue UV paint for machine use is 65 - 85 centipoise.

[0035] Apply the blue UV paint for machine use to the acrylic emulsion coating by gravure roll coating. The coating roll is a diamond honeycomb gravure roll, and the depth of the roll cells is about 50 μm and the width is about 45 μm.

[0036] The PET film coated with blue UV coating is pre-cured by ultraviolet light irradiation. The power of the ultraviolet lamp for pre-curing is 12KW. The PET film coated with blue UV coating passes through the ultraviolet lamp irradiation at a speed of 40-60M / min. When there are fingerprints on the surface of the coating under the state of incomplete curing, the cold transfer printing technology is adopted. The PET film coated with blue UV coating is rolled by a brightening plate roller. The rolling pressure of the brightening plate roller is 0.35MPa. The brightening plate roller is cooled by circulating cooling water at 20±2°C, and then dried at 50-60°C and irradiated by ultraviolet light for further curing. After slitting and packaging, it becomes a finished film product.

[0037] The structure of the product made is the same as that of Example 1 ( Figure 2 as shown), showing higher whiteness and brightness, and no colorful visual effect after optical interference. The sample is placed on an A4 paper and measured with a X-Rite color difference meter Ci6X. The L* value is 99.57, the a* value is -0.06, and the b* value is -0.33. The measured values of the used A4 paper are: L* value 90.85, a* value 1.07, b* value -6.28. The large changes in the L*, a*, and b* values indicate that the product has high brightness and whiteness. The product is subjected to a natural sunlight exposure aging test for 24 months, and no blistering phenomenon is observed, indicating that no peeling occurs between the composite layers.

Claims

1. A production process for high-whiteness and high-brightness film, comprising the following steps: A. Photolithographically fabricate parallel V-shaped recessed lines with a width of 10 - 20 μm, a depth of 0.5 - 1 times the width, and a distance of 2 - 4 times the width on a nickel plate, and then attach the nickel plate to the surface of a cylindrical plate roller to form a brightening plate roller; B. Preparation of UV coating: Mix and stir evenly UV coating and blue dye in a weight ratio of 100:(5 - 20) to obtain blue UV coating; C. Coat a transparent coating with a surface tension greater than 42 dynes on the base film; D. Coat the blue UV coating on the transparent coating of the base film, perform pre-curing under ultraviolet light irradiation. When the coating is not completely cured, roll it with the brightening plate roller so that the V-shaped recessed lines of the brightening plate roller are transferred to the UV adhesive layer to form protruding prism lines, and then cure it with ultraviolet light to become a high-whiteness and high-brightness film.

2. The process according to claim 1, characterized in that, In the step A, the depth of the V-shaped recessed lines is 0.6 - 0.7 times the width, and the distance is 2.5 - 3.5 times the width.

3. The process according to claim 1 or 2, characterized in that, In the step B, the weight ratio of the UV coating to the blue dye is 100:(10 - 15).

4. The process according to claim 1, characterized in that In the step C, the base film is a polyester film or a biaxially oriented polypropylene film.

5. The process according to claim 4, characterized in that: In the step C, the thickness of the transparent coating is 0.5 - 20 μm.

6. The process according to claim 4 or 5, characterized in that, In the step C, the transparent coating is an aqueous acrylic emulsion coating, and the coating amount after drying is 0.7-0.9 g / M 2 .

7. The process according to claim 4 or 5, characterized in that, In the step C, the transparent coating is an adhesive layer with a thickness of 0.3 - 20 μm.

8. The process according to claim 1, characterized in that, In the step D, before the blue UV coating is coated on the base film, it is preheated at 50 ± 2 °C.

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