PE black and white shading film and preparation method thereof

Abstract

The invention relates to a PE black and white shading film and a preparation method thereof, the PE black and white shading film comprises a black film and a white film, the black film comprises the following raw materials by weight: 80-100 parts of low density polyethylene, 1-1.5 parts of a cross-linking agent, 0.5-1.0 part of a lubricant, 0.1-0.5 part of an antioxidant, and 15-35 parts of carbon black; the white film is prepared from the following raw materials in parts by weight: 80 to 100 parts of low-density polyethylene, 1 to 1.5 parts of a cross-linking agent, 0.5 to 1.0 part of a lubricating agent, 0.1 to 0.5 part of an antioxidant and 5 to 20 parts of white filler, and the white filler comprises 4 to 20 parts of white flaky mica powder; the melt index of the low-density polyethylene in the black film is 0.7-0.9 g / 10min, and the melt index of the low-density polyethylene in the white film is 0.38-0.42 g / 10min. The PE black and white shading film prepared by the invention is high in shading rate and high in tearing strength.

Description

Technical Field

[0001] The present application relates to a polyethylene material, and more specifically, to a PE black-and-white light-shielding film and a preparation method thereof. Background Art

[0002] Black and white shading film includes black film and white film, which is mainly used on backlight sources to play the role of fixing and shading. It is also called shading film, black and white film, or black and white glue for short. It is used on TFT-LCD with high requirements for backlight shading or as a shading film for edible fungus cultivation. The black side provides shading effect, and the white side provides reflection and aesthetic effect. Polyethylene is a thermoplastic resin made by polymerization of ethylene. It is non-toxic and odorless, has good stability, and is suitable for the preparation of black and white shading film for long-term use. However, black and white films are usually made by co-extrusion of blow molding machines, and polyethylene materials have low surface energy. The boundary layer between the black and white films is further reduced in adhesion due to the low-strength area formed by the infiltration of low-molecular substances such as impurities introduced in the polymerization reaction process, low-molecular weight tailing parts, and processing aids. Bombarding the polyethylene film with activated inert gas and irradiating the polyethylene film with ultraviolet radiation can weaken the weak boundary layer, improve the bonding strength of the black and white films, and extend the service life of the black and white films, but the improvement effect is limited, and the processing cost is high, which is not suitable for large-scale film preparation. At the same time, black and white films are usually formed by adding black fillers and white fillers to form a black and white effect to increase the shading rate, but adding more fillers will further reduce the bonding performance of the black and white films. How to provide a black and white film with a strong bond between the black and white films and high tear strength to extend the service life of the black and white films has a broad market prospect. Summary of the invention

[0003] In order to solve the problem of high light shielding rate and high tear strength of PE black and white light shielding film, the present application provides a PE black and white light shielding film and a preparation method thereof.

[0004] In the first aspect, the present application provides a PE black and white shading film, including a black film and a white film, the black film includes the following raw materials in parts by weight: 80-100 parts of low-density polyethylene, 1-1.5 parts of a cross-linking agent, 0.5-1.0 parts of a lubricant, 0.1-0.5 parts of an antioxidant, and 15-35 parts of carbon black; the white film includes the following raw materials in parts by weight: 80-100 parts of low-density polyethylene, 1-1.5 parts of a cross-linking agent, 0.5-1.0 parts of a lubricant, 0.1-0.5 parts of an antioxidant, and 5-20 parts of a white filler, wherein the white filler includes 4-20 parts of white flaky mica powder; the melt index of the low-density polyethylene in the black film is 0.7-0.9 g / 10min, and the melt index of the low-density polyethylene in the white film is 0.38-0.42 g / 10min.

[0005] By adopting the above scheme, a certain mass of carbon black and white flaky mica powder are added as black filler and white filler to the black film and the white film respectively, so as to destroy the crystallinity of the black film and the white film to a certain extent, stabilize the overall shrinkage rate of the black and white shading films, and further limit the melting index of the black film and the white film to make them suitable for the components of the shading film of the present application. The shrinkage of the obtained black shading film is slightly greater than that of the white film, so that the black film can more tightly cover the partially raised white flaky mica powder on the surface of the white film after shrinkage, thereby improving the composite strength of the black film and the white film. When the melt index increases, the molecular weight is smaller, which will reduce the strength performance of the light-shielding film. At the same time, if the melt index is too large, the light-shielding film will shrink too much and cause debonding, affecting the overall performance of the light-shielding film. When the melt index is small, the shrinkage of the black film is not obvious, the degree of coverage of the protrusions on the surface of the white film is low, and the improvement of the tear strength is limited. Therefore, through repeated experiments, the applicant found that under this raw material setting, the overall viscosity, shrinkage, strength, etc. of the light-shielding film reached a relatively balanced level, the light-shielding effect is good, the black film and the white film of the light-shielding film are not easy to separate, and the tear strength performance is good.

[0006] In a specific embodiment, the melt index of the low-density polyethylene in the black film is 0.4-0.5 g / 10 min greater than that of the low-density polyethylene in the white film.

[0007] By adopting the above scheme, the shrinkage degree of the black film and the white film of the shading film is appropriate, and the shrinkage rate of the black film is slightly greater than that of the white film, which has a good effect on improving the composite strength of the white film. The difference will not be too large to cause debonding between the black and white shading films, nor will the difference be too small to limit the improvement of the composite strength of the two.

[0008] In a specific embodiment, the thickness of the black film is 0.2-0.35 mm, and the thickness of the white film is 0.2-0.4 mm.

[0009] By adopting the above scheme, the thickness of the black film and the white film is moderate, which is suitable for use in the black and white shading film of the present application.

[0010] In a specific embodiment, the mesh size of the white flake mica powder is 60-120 mesh.

[0011] By adopting the above scheme, the particle size of the flaky mica powder is suitable for use in the shading film of the present application, and can be relatively evenly distributed in the white film to form a white effect. The surface of the obtained white film can form certain protrusions, and can be embedded in the black film during the composite process with the black film, thus forming a better mechanical bond. It will not significantly affect the strength of the white film, nor will it significantly increase the composite strength of the two.

[0012] In a specific embodiment, the white filler further includes one or more of titanium dioxide, white carbon black, talc, and calcium carbonate.

[0013] By adopting the above scheme, titanium dioxide, white carbon black, talcum powder and calcium carbonate have a good filling effect on the white film, and the crystallization state of the white film is further adjusted, so that the shrinkage of the obtained white film is more uniform and well coordinated with the shrinkage of the black film, and the strength performance of the obtained black and white shading film is good.

[0014] In a specific embodiment, the white flaky mica powder is white flaky mica powder modified by an epoxy silane coupling agent.

[0015] By adopting the above scheme, the white flaky mica powder modified by the epoxy silane coupling agent has better compatibility with the white film matrix and is more evenly dispersed in the white film, further improving the strength performance of the obtained black and white shading film.

[0016] In a specific embodiment, the preparation steps of the white flaky mica powder modified by the epoxy silane coupling agent include: adding the white flaky mica powder to an ethanol aqueous solution, then adding the epoxy silane coupling agent, stirring evenly, heating, reacting, filtering, and drying to obtain the white flaky mica powder modified by the epoxy silane coupling agent.

[0017] By adopting the above scheme, the preparation steps are relatively simple, and the surface of the obtained epoxysilane coupling agent-modified white flaky mica powder has more active epoxy groups, is evenly dispersed in the white film, has good compatibility, and further improves the strength performance of the black and white shading film.

[0018] In a specific embodiment, the mass ratio of the epoxysilane coupling agent-modified white flaky mica powder to the low-density polyethylene in the white film is 1:(10-12).

[0019] By adopting the above scheme, the applicant conducted repeated experiments and found that when the mass ratio of white flaky mica powder modified by epoxy silane coupling agent and low-density polyethylene in the white film is 1: (10-12), the white flaky mica powder modified by epoxy silane coupling agent can be evenly distributed in the white film, forming relatively obvious protrusions on the surface of the white film without significantly reducing the strength of the white film itself.

[0020] In a second aspect, the present application provides a method for preparing a PE black and white light-shielding film, comprising the following steps:

[0021] S1: weighing the black film raw materials according to parts by weight and uniformly mixing them to obtain a black film mixture, and weighing the white film raw materials according to parts by weight and uniformly mixing them to obtain a white film mixture;

[0022] S2: adding the black film mixture and the white film mixture into the upper die head and the lower die head of the composite film blowing unit respectively, composite blow molding, cooling, stretching and shaping, and obtaining a black and white light-shielding film.

[0023] The preparation method of the above technical solution has a simple process and is suitable for the component composition of the PE black and white light-shielding film of the present application. The obtained black and white mica powder can be compounded relatively firmly.

[0024] In a specific embodiment, the mixing temperature is 100-130° C. and the mixing time is 10-25 minutes.

[0025] By adopting the above scheme, the mixture of black film and white film can be mixed more evenly, the additives are evenly dispersed, the interface adhesion between the additives, fillers and polyethylene in the prepared shading film is good, and it has good mechanical properties.

[0026] In summary, this application has the following beneficial effects:

[0027] 1. The present application adopts a black film and a white film to prepare a black and white light-shielding film. By using white flaky mica powder as a filler for the white film, the melting index of low-density polyethylene in the black and white films is limited, and the thickness of the black and white films, the mesh size of the white flaky mica powder, the difference in the melting index of low-density polyethylene in the black and white films, the type of filler, etc. are further limited, so that the black and white films can form shrinkage more stably after shaping, and the shrinkage of the black film is greater than that of the white film, and the white flaky mica powder protruding on the surface of the white film is more tightly coated, thereby avoiding the problem that the composite interface of the black film and the white film of the traditional composite film is not easy to bond due to the weak boundary layer. The obtained black and white light-shielding film has good light-shielding effect and high tear strength.

[0028] 2. The present application modifies white flaky mica powder with an epoxy silane coupling agent to make it more evenly dispersed in the white film, have better compatibility, and have better bonding strength with the black film, thereby improving the connection strength between the black film and the white film. By limiting the mass ratio of the white flaky mica powder modified with an epoxy silane coupling agent and the low-density polyethylene in the white film, the connection effect is further improved, and the tear strength of the resulting shading film is better. DETAILED DESCRIPTION

[0029] The following is a more specific description of the technical solution of the present invention in combination with several specific implementation examples. The embodiments are only partial embodiments of the present invention, not all of them. The following specific embodiments can be combined with each other, and the same or similar concepts or processes therein may not be repeated in some embodiments.

[0030] Unless otherwise specified, the experimental reagents in the preparation examples, embodiments and comparative examples are all conventional commercial brands or obtained through conventional preparation processes.

[0031] In the preparation examples, embodiments and comparative examples, the crosslinking agent is dicumyl peroxide, the lubricant is Dow POLYOX WSR301, and the antioxidant is antioxidant 1010.

[0032] Preparation Example

[0033] Preparation Example 1: White flaky mica powder modified with epoxy silane coupling agent.

[0034] Add 50g of 120 mesh white flaky mica powder to 200ml of 25%wt ethanol aqueous solution, stir evenly, then add 70g of epoxy silane coupling agent KH-560, stir evenly, react at 90°C, filter after the reaction, wash 3 times with deionized water, and dry to obtain epoxy silane coupling agent modified white flaky mica powder.

[0035] Preparation Example 2: Calcium carbonate modified with epoxysilane coupling agent.

[0036] Add 50g of 120 mesh calcium carbonate to 200ml of 25%wt ethanol aqueous solution, stir evenly, then add 70g of epoxysilane coupling agent KH-560, stir evenly, react at 90°C, filter after the reaction, wash 3 times with deionized water, and dry to obtain epoxysilane coupling agent modified calcium carbonate.

[0037] Example

[0038] Example 1

[0039] The PE black and white light-shielding film of this embodiment adopts the following raw materials by weight: 800g of low-density polyethylene, 10g of cross-linking agent, 5g of lubricant, 1g of antioxidant, and 200g of carbon black; the white film includes the following raw materials by weight: 1000g of low-density polyethylene, 10g of cross-linking agent, 5g of lubricant, 5g of antioxidant, and 200g of white filler, wherein the white filler is 120-mesh white flaky mica powder;

[0040] In this embodiment, the melt index of the low-density polyethylene in the black film is 0.9 g / 10 min, purchased from Yanshan Petrochemical 5000S*, and the melt index of the low-density polyethylene in the white film is 0.38-0.42 g / 10 min, purchased from Zhongyuan Petrochemical DGDS6097.

[0041] The preparation method of PE black and white shading film is as follows:

[0042] S1: weigh the black film raw materials according to parts by weight and mix them evenly to obtain a black film mixture, and weigh the white film raw materials according to parts by weight and mix them evenly to obtain a white film mixture; the mixing temperature is 100° C. and the mixing time is 20 minutes.

[0043] S2: Add the black film mixture and the white film mixture to the upper die head and the lower die head of the composite film blowing unit respectively, perform composite blow molding, cool and shape, stretch 5 times in the transverse direction and 5 times in the longitudinal direction to obtain a black and white light-shielding film.

[0044] Embodiment 2:

[0045] The PE black and white shading film of this embodiment adopts the following raw materials by weight: low-density polyethylene: 1000g, cross-linking agent 10g, lubricant 10g, antioxidant 1g, carbon black: 200g; the white film includes the following raw materials by weight: low-density polyethylene 800g, cross-linking agent 10g, lubricant 5g, antioxidant 5g, white filler: 200g, the white filler is 120 mesh white flaky mica powder;

[0046] In this embodiment, the melt index of the low-density polyethylene in the black film is 0.9 g / 10 min, purchased from Yanshan Petrochemical 5000S*, and the melt index of the low-density polyethylene in the white film is 0.38-0.42 g / 10 min, purchased from Zhongyuan Petrochemical DGDS6097.

[0047] The preparation method of PE black and white shading film is as follows:

[0048] S1: weigh the black film raw materials according to parts by weight and mix them evenly to obtain a black film mixture, and weigh the white film raw materials according to parts by weight and mix them evenly to obtain a white film mixture; the mixing temperature is 100° C. and the mixing time is 20 minutes.

[0049] S2: Add the black film mixture and the white film mixture to the upper die head and the lower die head of the composite film blowing unit respectively, perform composite blow molding, cool and shape, stretch 5 times in the transverse direction and 5 times in the longitudinal direction to obtain a black and white light-shielding film.

[0050] Embodiment 3:

[0051] The PE black and white shading film of this embodiment adopts the following raw materials by weight: low-density polyethylene: 900g, cross-linking agent 10g, lubricant 10g, antioxidant 1g, carbon black: 200g; the white film includes the following raw materials by weight: low-density polyethylene 900g, cross-linking agent 10g, lubricant 5g, antioxidant 5g, white filler: 50g, the white filler is 120 mesh white flaky mica powder;

[0052] In this embodiment, the melt index of the low-density polyethylene in the black film is 0.9 g / 10 min, purchased from Yanshan Petrochemical 5000S*, and the melt index of the low-density polyethylene in the white film is 0.38-0.42 g / 10 min, purchased from Zhongyuan Petrochemical DGDS6097.

[0053] The preparation method of PE black and white shading film is as follows:

[0054] S1: weigh the black film raw materials according to parts by weight and mix them evenly to obtain a black film mixture, and weigh the white film raw materials according to parts by weight and mix them evenly to obtain a white film mixture; the mixing temperature is 100° C. and the mixing time is 20 minutes.

[0055] S2: Add the black film mixture and the white film mixture to the upper die head and the lower die head of the composite film blowing unit respectively, perform composite blow molding, cool and shape, stretch 5 times in the transverse direction and 5 times in the longitudinal direction to obtain a black and white light-shielding film.

[0056] Example 4

[0057] The PE black and white light-shielding film of this embodiment adopts the following raw materials by weight: 800g of low-density polyethylene, 10g of cross-linking agent, 5g of lubricant, 1g of antioxidant, and 200g of carbon black; the white film includes the following raw materials by weight: 1000g of low-density polyethylene, 10g of cross-linking agent, 5g of lubricant, 5g of antioxidant, and 200g of white filler, wherein the white filler is 120-mesh white flaky mica powder;

[0058] In this embodiment, the melt index of the low-density polyethylene in the black film is 0.7 g / 10 min, purchased from Tianjin United TJDL-9475, and the melt index of the low-density polyethylene in the white film is 0.38-0.42 g / 10 min, purchased from Zhongyuan Petrochemical DGDS6097.

[0059] The preparation method of PE black and white shading film is as follows:

[0060] S1: weigh the black film raw materials according to parts by weight and mix them evenly to obtain a black film mixture, and weigh the white film raw materials according to parts by weight and mix them evenly to obtain a white film mixture; the mixing temperature is 100° C. and the mixing time is 20 minutes.

[0061] S2: Add the black film mixture and the white film mixture to the upper die head and the lower die head of the composite film blowing unit respectively, perform composite blow molding, cool and shape, stretch 5 times in the transverse direction and 5 times in the longitudinal direction to obtain a black and white light-shielding film.

[0062] Example 5

[0063] The PE black and white shading film of this embodiment adopts the following raw materials by weight: 800g of low-density polyethylene, 10g of cross-linking agent, 5g of lubricant, 1g of antioxidant, and 200g of carbon black; the white film includes the following raw materials by weight: 1000g of low-density polyethylene, 10g of cross-linking agent, 5g of lubricant, 5g of antioxidant, and 200g of white filler, wherein the white filler is 60-mesh white flaky mica powder;

[0064] In this embodiment, the melt index of the low-density polyethylene in the black film is 0.9 g / 10 min, purchased from Yanshan Petrochemical 5000S*, and the melt index of the low-density polyethylene in the white film is 0.38-0.42 g / 10 min, purchased from Zhongyuan Petrochemical DGDS6097.

[0065] The preparation method of PE black and white shading film is as follows:

[0066] S1: weigh the black film raw materials according to parts by weight and mix them evenly to obtain a black film mixture, and weigh the white film raw materials according to parts by weight and mix them evenly to obtain a white film mixture; the mixing temperature is 100° C. and the mixing time is 20 minutes.

[0067] S2: Add the black film mixture and the white film mixture to the upper die head and the lower die head of the composite film blowing unit respectively, perform composite blow molding, cool and shape, stretch 5 times in the transverse direction and 5 times in the longitudinal direction to obtain a black and white light-shielding film.

[0068] Example 6

[0069] The PE black and white light-shielding film of this embodiment adopts the following raw materials by weight: 800g of low-density polyethylene, 10g of cross-linking agent, 5g of lubricant, 1g of antioxidant, and 200g of carbon black; the white film comprises the following raw materials by weight: 1000g of low-density polyethylene, 10g of cross-linking agent, 5g of lubricant, 5g of antioxidant, and 200g of white filler, wherein the white filler is 200-mesh white flaky mica powder;

[0070] In this embodiment, the melt index of the low-density polyethylene in the black film is 0.9 g / 10 min, purchased from Yanshan Petrochemical 5000S*, and the melt index of the low-density polyethylene in the white film is 0.38-0.42 g / 10 min, purchased from Zhongyuan Petrochemical DGDS6097.

[0071] The preparation method of PE black and white shading film is as follows:

[0072] S1: weigh the black film raw materials according to parts by weight and mix them evenly to obtain a black film mixture, and weigh the white film raw materials according to parts by weight and mix them evenly to obtain a white film mixture; the mixing temperature is 100° C. and the mixing time is 20 minutes.

[0073] S2: Add the black film mixture and the white film mixture to the upper die head and the lower die head of the composite film blowing unit respectively, perform composite blow molding, cool and shape, stretch 5 times in the transverse direction and 5 times in the longitudinal direction to obtain a black and white light-shielding film.

[0074] Example 7

[0075] The PE black and white light-shielding film of this embodiment adopts the following raw materials by weight: 800g of low-density polyethylene, 10g of cross-linking agent, 5g of lubricant, 1g of antioxidant, and 200g of carbon black; the white film comprises the following raw materials by weight: 1000g of low-density polyethylene, 10g of cross-linking agent, 5g of lubricant, 5g of antioxidant, and 200g of white filler, wherein the white filler is the white flaky mica powder modified by the epoxy silane coupling agent obtained in Preparation Example 1;

[0076] In this embodiment, the melt index of the low-density polyethylene in the black film is 0.9 g / 10 min, purchased from Yanshan Petrochemical 5000S*, and the melt index of the low-density polyethylene in the white film is 0.38-0.42 g / 10 min, purchased from Zhongyuan Petrochemical DGDS6097.

[0077] The preparation method of PE black and white shading film is as follows:

[0078] S1: weigh the black film raw materials according to parts by weight and mix them evenly to obtain a black film mixture, and weigh the white film raw materials according to parts by weight and mix them evenly to obtain a white film mixture; the mixing temperature is 100° C. and the mixing time is 20 minutes.

[0079] S2: Add the black film mixture and the white film mixture to the upper die head and the lower die head of the composite film blowing unit respectively, perform composite blow molding, cool and shape, stretch 5 times in the transverse direction and 5 times in the longitudinal direction to obtain a black and white light-shielding film.

[0080] Example 8

[0081] The PE black and white light-shielding film of this embodiment adopts the following raw materials by weight: 800g of low-density polyethylene, 10g of cross-linking agent, 5g of lubricant, 1g of antioxidant, and 200g of carbon black; the white film includes the following raw materials by weight: 1000g of low-density polyethylene, 10g of cross-linking agent, 5g of lubricant, 5g of antioxidant, and 200g of white filler, wherein the white filler is 150g of white flaky mica powder modified by epoxy silane coupling agent obtained in Preparation Example 1, and 50g of 100-mesh calcium carbonate;

[0082] In this embodiment, the melt index of the low-density polyethylene in the black film is 0.9 g / 10 min, purchased from Yanshan Petrochemical 5000S*, and the melt index of the low-density polyethylene in the white film is 0.38-0.42 g / 10 min, purchased from Zhongyuan Petrochemical DGDS6097.

[0083] The preparation method of PE black and white shading film is as follows:

[0084] S1: weigh the black film raw materials according to parts by weight and mix them evenly to obtain a black film mixture, and weigh the white film raw materials according to parts by weight and mix them evenly to obtain a white film mixture; the mixing temperature is 100° C. and the mixing time is 20 minutes.

[0085] S2: Add the black film mixture and the white film mixture to the upper die head and the lower die head of the composite film blowing unit respectively, perform composite blow molding, cool and shape, stretch 5 times in the transverse direction and 5 times in the longitudinal direction to obtain a black and white light-shielding film.

[0086] Example 9

[0087] The PE black and white light-shielding film of this embodiment adopts the following raw materials by weight: 800g of low-density polyethylene, 10g of cross-linking agent, 5g of lubricant, 1g of antioxidant, and 200g of carbon black; the white film comprises the following raw materials by weight: 1000g of low-density polyethylene, 10g of cross-linking agent, 5g of lubricant, 5g of antioxidant, and 200g of white filler, wherein the white filler is 100g of white flaky mica powder modified by epoxy silane coupling agent obtained in Preparation Example 1, and 100g of 120-mesh calcium carbonate;

[0088] In this embodiment, the melt index of the low-density polyethylene in the black film is 0.9 g / 10 min, purchased from Yanshan Petrochemical 5000S*, and the melt index of the low-density polyethylene in the white film is 0.38-0.42 g / 10 min, purchased from Zhongyuan Petrochemical DGDS6097.

[0089] The preparation method of PE black and white shading film is as follows:

[0090] S1: weigh the black film raw materials according to parts by weight and mix them evenly to obtain a black film mixture, and weigh the white film raw materials according to parts by weight and mix them evenly to obtain a white film mixture; the mixing temperature is 100° C. and the mixing time is 20 minutes.

[0091] S2: Add the black film mixture and the white film mixture to the upper die head and the lower die head of the composite film blowing unit respectively, perform composite blow molding, cool and shape, stretch 5 times in the transverse direction and 5 times in the longitudinal direction to obtain a black and white light-shielding film.

[0092] Comparative Example

[0093] Comparative Example 1

[0094] The PE black and white shading film of this embodiment adopts the following raw materials by weight: 800g of low-density polyethylene, 10g of cross-linking agent, 5g of lubricant, 1g of antioxidant, and 200g of carbon black; the white film includes the following raw materials by weight: 1000g of low-density polyethylene, 10g of cross-linking agent, 5g of lubricant, 5g of antioxidant, and 200g of white filler, wherein the white filler is white flaky mica powder;

[0095] In this embodiment, the melt index of the low-density polyethylene in the black film is 0.25-0.55 g / 10 min, purchased from Daqing Petrochemical 6200B*, and the melt index of the low-density polyethylene in the white film is 0.38-0.42 g / 10 min, purchased from Zhongyuan Petrochemical DGDS6097.

[0096] The preparation method of PE black and white shading film is as follows:

[0097] S1: weigh the black film raw materials according to parts by weight and mix them evenly to obtain a black film mixture, and weigh the white film raw materials according to parts by weight and mix them evenly to obtain a white film mixture; the mixing temperature is 100° C. and the mixing time is 20 minutes.

[0098] S2: Add the black film mixture and the white film mixture to the upper die head and the lower die head of the composite film blowing unit respectively, perform composite blow molding, cool and shape, stretch 5 times in the transverse direction and 5 times in the longitudinal direction to obtain a black and white light-shielding film.

[0099] Comparative Example 2

[0100] The PE black and white light-shielding film of this embodiment adopts the following raw materials by weight: 800g of low-density polyethylene, 10g of cross-linking agent, 5g of lubricant, 1g of antioxidant, and 200g of carbon black; the white film comprises the following raw materials by weight: 1000g of low-density polyethylene, 10g of cross-linking agent, 5g of lubricant, 5g of antioxidant, and 200g of white filler, wherein the white filler is the epoxy silane coupling agent modified calcium carbonate obtained in Preparation Example 2;

[0101] In this embodiment, the melt index of the low-density polyethylene in the black film is 0.9 g / 10 min, purchased from Yanshan Petrochemical 5000S*, and the melt index of the low-density polyethylene in the white film is 0.38-0.42 g / 10 min, purchased from Zhongyuan Petrochemical DGDS6097.

[0102] The preparation method of PE black and white shading film is as follows:

[0103] S1: weigh the black film raw materials according to parts by weight and mix them evenly to obtain a black film mixture, and weigh the white film raw materials according to parts by weight and mix them evenly to obtain a white film mixture; the mixing temperature is 100° C. and the mixing time is 20 minutes.

[0104] S2: Add the black film mixture and the white film mixture to the upper die head and the lower die head of the composite film blowing unit respectively, perform composite blow molding, cool and shape, stretch 5 times in the transverse direction and 5 times in the longitudinal direction to obtain a black and white light-shielding film.

[0105] Performance testing

[0106] Test 1: The right-angle tear strength of the PE black and white light-shielding films prepared in the examples and comparative examples was tested with reference to standard QB / T 1130-1991.

[0107] Test 2: The shading performance of the PE black and white shading films prepared in the examples and comparative examples was tested by the light transmission box method with reference to the standard AATCC-148-79.

[0108] The results are summarized in Table 1.

[0109] Table 1 Tear strength (kN / m) Shading rate (%) Example 1 150 100 Example 2 146 100 Example 3 151 100 Example 4 140 100 Example 5 147 100 Example 6 139 100 Example 7 158 100 Example 8 163 100 Example 9 169 100 Comparative Example 1 137 100 Comparative Example 2 120 100

[0110] In combination with Examples 1-3, Comparative Example 1 and Table 1, the present application adopts white flaky mica powder as the filler of the white film and limits the melt index of low-density polyethylene in the black film and the white film, so that the obtained black and white shading film has good shading effect and high tear strength.

[0111] In combination with Example 1, Example 4 and Table 1, the present application limits the difference in melt index between the black film and the white film, thereby achieving better shrinkage coating effect and higher tear strength.

[0112] In combination with Example 1, Examples 5-6, Example 8 and Table 1, the present application further limits the mesh size of the white flaky mica powder and adds other fillers to make the black and white film shrink more stably after shaping, thereby further improving the strength performance.

[0113] In combination with Example 1, Examples 7-9, Comparative Example 2 and Table 1, the present application limits the mass ratio of white flaky mica powder to polyethylene by modifying the white flaky mica powder. The modified white flaky mica powder has better compatibility in the film material, better connection effect in black film and white film, and higher tear strength.

[0114] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A PE black and white light-shielding film, characterized in that: The PE black and white shading film includes a black film and a white film, wherein the black film includes the following raw materials in parts by weight: 80-100 parts of low-density polyethylene, 1-1.5 parts of a cross-linking agent, 0.5-1.0 parts of a lubricant, 0.1-0.5 parts of an antioxidant, and 15-35 parts of carbon black; the white film includes the following raw materials in parts by weight: 80-100 parts of low-density polyethylene, 1-1.5 parts of a cross-linking agent, 0.5-1.0 parts of a lubricant, 0.1-0.5 parts of an antioxidant, and 5-20 parts of a white filler, wherein the white filler includes 4-20 parts of white flaky mica powder; the melt index of the low-density polyethylene in the black film is 0.7-0.9 g / 10 min, and the melt index of the low-density polyethylene in the white film is 0.38-0.42 g / 10 min.

2. The PE black and white light-shielding film according to claim 1, characterized in that: The melt index of the low-density polyethylene in the black film is 0.4-0.5 g / 10 min greater than that of the low-density polyethylene in the white film.

3. The PE black and white light-shielding film according to claim 1, characterized in that: The thickness of the black film is 0.2-0.35 mm, and the thickness of the white film is 0.2-0.4 mm.

4. The PE black and white light-shielding film according to claim 1, characterized in that: The mesh number of the white flaky mica powder is 60-120 meshes.

5. The PE black and white light-shielding film according to claim 1, characterized in that: The white filler also includes one or more of titanium dioxide, white carbon black, talcum powder, and calcium carbonate.

6. The PE black and white light-shielding film according to claim 1, characterized in that: The white flaky mica powder is white flaky mica powder modified by an epoxy silane coupling agent.

7. The PE black and white light-shielding film according to claim 6, characterized in that: The preparation steps of the epoxysilane coupling agent modified white flaky mica powder include: adding the white flaky mica powder into an ethanol aqueous solution, then adding the epoxysilane coupling agent, stirring evenly, heating, reacting, filtering, and drying to obtain the epoxysilane coupling agent modified white flaky mica powder.

8. The PE black and white light-shielding film according to claim 6, characterized in that: The mass ratio of the epoxysilane coupling agent modified white flaky mica powder to the low-density polyethylene in the white film is 1:(10-12).

9. A method for preparing the PE black and white light-shielding film according to any one of claims 1 to 8, characterized in that: The preparation method comprises the following steps: S1: weighing the black film raw materials according to parts by weight and uniformly mixing them to obtain a black film mixture, and weighing the white film raw materials according to parts by weight and uniformly mixing them to obtain a white film mixture; S2: adding the black film mixture and the white film mixture into the upper die head and the lower die head of the composite film blowing unit respectively, composite blow molding, cooling, stretching and shaping, and obtaining a black and white light-shielding film.

10. The method for preparing the PE black and white light-shielding film according to claim 9, characterized in that: The mixing temperature is 100-130° C., and the mixing time is 10-25 minutes.