PE black and white light shielding film and preparation method thereof

Abstract

This application relates to a PE black and white light-blocking film and its preparation method. The PE black and white light-blocking film includes a black film and a white film. The black film comprises the following raw materials in parts by weight: 80-100 parts of low-density polyethylene, 1-1.5 parts of crosslinking agent, 0.5-1.0 parts of lubricant, 0.1-0.5 parts of antioxidant, and 15-35 parts of carbon black. The white film comprises the following raw materials in parts by weight: 80-100 parts of low-density polyethylene, 1-1.5 parts of crosslinking agent, 0.5-1.0 parts of lubricant, 0.1-0.5 parts of antioxidant, and 5-20 parts of white filler, including 4-20 parts of white flake 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. The PE black and white light-blocking film obtained by this application has high light-blocking rate and high tear strength.

Description

Technical Field

[0001] This application relates to a polyethylene material, and more specifically, to a PE black and white light-blocking film and its preparation method. Background Technology

[0002] Black and white light-blocking film includes black film and white film, mainly used on backlights to fix and block light. It is also called light-blocking sheet, black and white film, or simply black and white adhesive. It is used on TFT-LCDs with high backlight blocking requirements or as a light-blocking film for edible fungi cultivation. The black side provides the light-blocking effect, while the white side provides reflection and aesthetic effect. Polyethylene is a thermoplastic resin obtained by polymerizing ethylene. It is non-toxic, odorless, and has good stability, making it suitable for preparing black and white light-blocking film for long-term use. However, black and white films are usually produced by co-extrusion using a blow molding machine. Polyethylene material has low surface energy, and the boundary layer between the black and white films is further weakened by the low-strength regions formed by impurities, low-molecular-weight tailings, and processing aids introduced during the polymerization process. Bombarding the polyethylene film with activated inert gas or subjecting it to ultraviolet radiation can weaken the weak boundary layer, improve the bonding strength between the black and white films, and extend the service life of the black and white films. However, the improvement effect is limited, and the processing cost is high, making it unsuitable for large-scale film production. At the same time, black and white films are usually made by adding black and white fillers to create a black and white effect and improve the light-blocking rate. However, adding more fillers will further reduce the bonding performance of the black and white films. Therefore, providing a black and white film with strong adhesion 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] To address the issues of high shading rate and high tear strength in PE black and white shading film, this application provides a PE black and white shading film and its preparation method.

[0004] In a first aspect, this application provides a PE black and white light-blocking film, comprising a black film and a white film. The black film comprises the following raw materials in parts by weight: 80-100 parts of low-density polyethylene, 1-1.5 parts of crosslinking agent, 0.5-1.0 parts of lubricant, 0.1-0.5 parts of antioxidant, and 15-35 parts of carbon black. The white film comprises the following raw materials in parts by weight: 80-100 parts of low-density polyethylene, 1-1.5 parts of crosslinking agent, 0.5-1.0 parts of lubricant, 0.1-0.5 parts of antioxidant, and 5-20 parts of white filler, wherein the white filler comprises 4-20 parts of white flake 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.

[0005] By adopting the above-mentioned scheme, the black film and white film are respectively filled with a certain mass of carbon black and white flake mica powder as black fillers and white fillers, which to a certain extent disrupts the crystallinity of the black film and white film, stabilizes the overall shrinkage rate of the black and white light-blocking film, and further limits the melt index of the black film and white film to make them suitable for the composition of the light-blocking film of this application. The resulting light-blocking film has a slightly larger shrinkage of the black film than the white film, which makes the black film more tightly coated with the partially protruding white flake mica powder on the surface of the white film after shrinkage, thereby improving the composite strength of the black film and white film. When the melt index increases, the molecular weight decreases, which reduces the strength of the light-shielding film. At the same time, if the melt index is too high, the light-shielding film shrinks too much, which can also cause delamination and affect the overall performance of the light-shielding film. When the melt index is low, 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 tear strength is limited. Therefore, through repeated experiments, the applicant found that under this raw material setting, the viscosity, shrinkage, and strength of the light-shielding film are relatively balanced, the light-shielding effect is good, the black film and white film of the produced light-shielding film are not easy to separate, and the tear strength performance is good.

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

[0007] By adopting the above solution, the shrinkage of the black and white films of the light-blocking film is appropriate. 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 is not too large, which would cause the black and white light-blocking films to delaminate, nor is the difference too small, which would limit the improvement of the composite strength of the two.

[0008] In one specific feasible implementation, 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-mentioned approach, the thickness of the black and white films is moderate, making them suitable for use in the black and white light-blocking film of this application.

[0010] In one specific feasible implementation, the white flaky mica powder has a mesh size of 60-120 mesh.

[0011] By adopting the above scheme, the particle size of the flake mica powder is suitable for use in the light-shielding film of this application. It can be distributed relatively evenly in the white film to form a white effect. The surface of the white film can form certain protrusions. During the composite process with the black film, it can be embedded in the black film and form a good mechanical bond. It will not significantly affect the strength of the white film, nor will it significantly reduce the improvement of the composite strength of the two.

[0012] In one specific implementation, the white filler also includes one or more of titanium dioxide, silica, talc, and calcium carbonate.

[0013] By adopting the above-mentioned scheme, titanium dioxide, silica, talc, and calcium carbonate have a good filling effect on the white film, and further adjust the crystallization state of the white film. The resulting white film shrinks more evenly and matches the shrinkage of the black film well, resulting in a black and white light-blocking film with good strength performance.

[0014] In one specific feasible implementation, the white flaky mica powder is white flaky mica powder modified with an epoxy silane coupling agent.

[0015] By adopting the above scheme, the white flake mica powder modified with 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 prepared black and white light-blocking film.

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

[0017] By adopting the above scheme, the preparation steps are relatively simple. The obtained epoxy-silane coupling agent modified white flake mica powder has a large number of active epoxy groups on its surface, which are evenly dispersed in the white film and have good compatibility, further improving the strength performance of the black and white light-blocking film.

[0018] In one specific feasible implementation, the mass ratio of low-density polyethylene in the epoxy silane coupling agent-modified white flake mica powder and white film is 1:(10-12).

[0019] By adopting the above scheme and conducting repeated experiments, the applicant found that when the mass ratio of low-density polyethylene in the white flake mica powder modified by epoxy silane coupling agent and the white film is 1:(10-12), the white flake 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] Secondly, this application provides a method for preparing a PE black and white light-blocking film, comprising the following steps:

[0021] S1: Weigh the black film raw materials according to the weight parts and mix them evenly to obtain the black film mixture; weigh the white film raw materials according to the weight parts and mix them evenly to obtain the white film mixture.

[0022] S2: Add the black film mixture and the white film mixture to the upper and lower molds of the composite film blow molding machine, respectively, perform composite blow molding, cooling, stretching and shaping to obtain a black and white light-blocking film.

[0023] The preparation method of the above technical solution is simple and suitable for the composition of the PE black and white light-blocking film of this application. The black and white mica powders obtained can be composited relatively firmly.

[0024] In one specific feasible implementation, 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, and the resulting light-shielding film has good interfacial adhesion between additives, fillers and polyethylene, and exhibits good mechanical properties.

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

[0027] 1. This application uses a black and white film composite to produce a black and white light-blocking film. By using white flake mica powder as the filler for the white film, limiting the melt index of low-density polyethylene in the black and white films, and further limiting the thickness of the black and white films, the mesh size of the white flake mica powder, the difference in melt index of low-density polyethylene in the black and white films, and the type of filler, the black and white films can form a relatively stable shrinkage after shaping. The shrinkage of the black film is greater than that of the white film, which tightly covers the raised white flake mica powder on the surface of the white film. This avoids the problem of weak boundary layer adhesion at the composite interface of the black and white films in traditional composite films. The resulting black and white light-blocking film has good light-blocking effect and high tear strength.

[0028] 2. This application modifies white flake mica powder with an epoxy silane coupling agent, making it more uniformly dispersed in the white film, with better compatibility and better adhesion to the black film, thereby improving the connection strength between the black and white films. By limiting the mass ratio of epoxy silane coupling agent-modified white flake mica powder and low-density polyethylene in the white film, the connection effect is further improved, and the resulting light-shielding film exhibits better tear strength. Detailed Implementation

[0029] The following describes the technical solution of the present invention in more detail with reference to several specific implementation examples. The embodiments are only some 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 may not be repeated in some embodiments.

[0030] Unless otherwise specified, the experimental reagents used in the preparation examples, embodiments, and comparative examples are all from commercially available 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 flake mica powder modified with epoxy silane coupling agent.

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

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

[0036] Add 50g of 120-mesh calcium carbonate to 200ml of 25%wt ethanol aqueous solution, stir well, then add 70g of epoxy silane coupling agent KH-560, stir well, react at 90℃, filter after the reaction is complete, wash three times with deionized water, and dry to obtain epoxy silane coupling agent modified calcium carbonate.

[0037] Example

[0038] Example 1

[0039] The PE black and white light-blocking film of this embodiment uses the following raw materials by weight: 800g of low-density polyethylene, 10g of crosslinking 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 crosslinking agent, 5g of lubricant, 5g of antioxidant, and 200g of white filler, wherein the white filler is 120-mesh white flake mica powder;

[0040] In this embodiment, the melt index of low-density polyethylene in the black film is 0.9 g / 10 min, purchased from Yanshan Petrochemical 5000S*, and the melt index of 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 light-blocking film is as follows:

[0042] S1: Weigh the black film raw materials according to the weight parts and mix them evenly to obtain the black film mixture. Weigh the white film raw materials according to the weight parts and mix them evenly to obtain the white film mixture. The mixing temperature is 100℃ and the mixing time is 20 minutes.

[0043] S2: Add the black film mixture and the white film mixture to the upper and lower molds of the composite film blow molding machine, respectively, perform composite blow molding, cool and shape, stretch 5 times laterally and 5 times longitudinally to obtain a black and white light-blocking film.

[0044] Example 2:

[0045] The PE black and white light-blocking film of this embodiment uses the following raw materials by weight: low-density polyethylene: 1000g, crosslinking agent: 10g, lubricant: 10g, antioxidant: 1g, carbon black: 200g; the white film includes the following raw materials by weight: low-density polyethylene: 800g, crosslinking agent: 10g, lubricant: 5g, antioxidant: 5g, white filler: 200g, the white filler being 120-mesh white flake mica powder;

[0046] In this embodiment, the melt index of low-density polyethylene in the black film is 0.9 g / 10 min, purchased from Yanshan Petrochemical 5000S*, and the melt index of 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 light-blocking film is as follows:

[0048] S1: Weigh the black film raw materials according to the weight parts and mix them evenly to obtain the black film mixture. Weigh the white film raw materials according to the weight parts and mix them evenly to obtain the white film mixture. The mixing temperature is 100℃ and the mixing time is 20 minutes.

[0049] S2: Add the black film mixture and the white film mixture to the upper and lower molds of the composite film blow molding machine, respectively, perform composite blow molding, cool and shape, stretch 5 times laterally and 5 times longitudinally to obtain a black and white light-blocking film.

[0050] Example 3:

[0051] The PE black and white light-blocking film of this embodiment uses the following raw materials by weight: low-density polyethylene: 900g, crosslinking agent: 10g, lubricant: 10g, antioxidant: 1g, carbon black: 200g; the white film includes the following raw materials by weight: low-density polyethylene: 900g, crosslinking agent: 10g, lubricant: 5g, antioxidant: 5g, white filler: 50g, the white filler being 120-mesh white flake mica powder;

[0052] In this embodiment, the melt index of low-density polyethylene in the black film is 0.9 g / 10 min, purchased from Yanshan Petrochemical 5000S*, and the melt index of 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 light-blocking film is as follows:

[0054] S1: Weigh the black film raw materials according to the weight parts and mix them evenly to obtain the black film mixture. Weigh the white film raw materials according to the weight parts and mix them evenly to obtain the white film mixture. The mixing temperature is 100℃ and the mixing time is 20 minutes.

[0055] S2: Add the black film mixture and the white film mixture to the upper and lower molds of the composite film blow molding machine, respectively, perform composite blow molding, cool and shape, stretch 5 times laterally and 5 times longitudinally to obtain a black and white light-blocking film.

[0056] Example 4

[0057] The PE black and white light-blocking film of this embodiment uses the following raw materials by weight: 800g of low-density polyethylene, 10g of crosslinking 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 crosslinking agent, 5g of lubricant, 5g of antioxidant, and 200g of white filler, wherein the white filler is 120-mesh white flake mica powder;

[0058] In this embodiment, the melt index of low-density polyethylene in the black film is 0.7 g / 10 min, purchased from Tianjin United TJDL-9475, and the melt index of 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 light-blocking film is as follows:

[0060] S1: Weigh the black film raw materials according to the weight parts and mix them evenly to obtain the black film mixture. Weigh the white film raw materials according to the weight parts and mix them evenly to obtain the white film mixture. The mixing temperature is 100℃ and the mixing time is 20 minutes.

[0061] S2: Add the black film mixture and the white film mixture to the upper and lower molds of the composite film blow molding machine, respectively, perform composite blow molding, cool and shape, stretch 5 times laterally and 5 times longitudinally to obtain a black and white light-blocking film.

[0062] Example 5

[0063] The PE black and white light-blocking film of this embodiment uses the following raw materials by weight: 800g of low-density polyethylene, 10g of crosslinking 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 crosslinking agent, 5g of lubricant, 5g of antioxidant, and 200g of white filler, wherein the white filler is 60-mesh white flake mica powder;

[0064] In this embodiment, the melt index of low-density polyethylene in the black film is 0.9 g / 10 min, purchased from Yanshan Petrochemical 5000S*, and the melt index of 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 light-blocking film is as follows:

[0066] S1: Weigh the black film raw materials according to the weight parts and mix them evenly to obtain the black film mixture. Weigh the white film raw materials according to the weight parts and mix them evenly to obtain the white film mixture. The mixing temperature is 100℃ and the mixing time is 20 minutes.

[0067] S2: Add the black film mixture and the white film mixture to the upper and lower molds of the composite film blow molding machine, respectively, perform composite blow molding, cool and shape, stretch 5 times laterally and 5 times longitudinally to obtain a black and white light-blocking film.

[0068] Example 6

[0069] The PE black and white light-blocking film of this embodiment uses the following raw materials by weight: 800g of low-density polyethylene, 10g of crosslinking 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 crosslinking agent, 5g of lubricant, 5g of antioxidant, and 200g of white filler, wherein the white filler is 200-mesh white flake mica powder;

[0070] In this embodiment, the melt index of low-density polyethylene in the black film is 0.9 g / 10 min, purchased from Yanshan Petrochemical 5000S*, and the melt index of 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 light-blocking film is as follows:

[0072] S1: Weigh the black film raw materials according to the weight parts and mix them evenly to obtain the black film mixture. Weigh the white film raw materials according to the weight parts and mix them evenly to obtain the white film mixture. The mixing temperature is 100℃ and the mixing time is 20 minutes.

[0073] S2: Add the black film mixture and the white film mixture to the upper and lower molds of the composite film blow molding machine, respectively, perform composite blow molding, cool and shape, stretch 5 times laterally and 5 times longitudinally to obtain a black and white light-blocking film.

[0074] Example 7

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

[0076] In this embodiment, the melt index of low-density polyethylene in the black film is 0.9 g / 10 min, purchased from Yanshan Petrochemical 5000S*, and the melt index of 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 light-blocking film is as follows:

[0078] S1: Weigh the black film raw materials according to the weight parts and mix them evenly to obtain the black film mixture. Weigh the white film raw materials according to the weight parts and mix them evenly to obtain the white film mixture. The mixing temperature is 100℃ and the mixing time is 20 minutes.

[0079] S2: Add the black film mixture and the white film mixture to the upper and lower molds of the composite film blow molding machine, respectively, perform composite blow molding, cool and shape, stretch 5 times laterally and 5 times longitudinally to obtain a black and white light-blocking film.

[0080] Example 8

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

[0082] In this embodiment, the melt index of low-density polyethylene in the black film is 0.9 g / 10 min, purchased from Yanshan Petrochemical 5000S*, and the melt index of 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 light-blocking film is as follows:

[0084] S1: Weigh the black film raw materials according to the weight parts and mix them evenly to obtain the black film mixture. Weigh the white film raw materials according to the weight parts and mix them evenly to obtain the white film mixture. The mixing temperature is 100℃ and the mixing time is 20 minutes.

[0085] S2: Add the black film mixture and the white film mixture to the upper and lower molds of the composite film blow molding machine, respectively, perform composite blow molding, cool and shape, stretch 5 times laterally and 5 times longitudinally to obtain a black and white light-blocking film.

[0086] Example 9

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

[0088] In this embodiment, the melt index of low-density polyethylene in the black film is 0.9 g / 10 min, purchased from Yanshan Petrochemical 5000S*, and the melt index of 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 light-blocking film is as follows:

[0090] S1: Weigh the black film raw materials according to the weight parts and mix them evenly to obtain the black film mixture. Weigh the white film raw materials according to the weight parts and mix them evenly to obtain the white film mixture. The mixing temperature is 100℃ and the mixing time is 20 minutes.

[0091] S2: Add the black film mixture and the white film mixture to the upper and lower molds of the composite film blow molding machine, respectively, perform composite blow molding, cool and shape, stretch 5 times laterally and 5 times longitudinally to obtain a black and white light-blocking film.

[0092] Comparative Example

[0093] Comparative Example 1

[0094] The PE black and white light-blocking film of this embodiment uses the following raw materials by weight: 800g of low-density polyethylene, 10g of crosslinking 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 crosslinking agent, 5g of lubricant, 5g of antioxidant, and 200g of white filler, wherein the white filler is white flake mica powder;

[0095] In this embodiment, the melt index of 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 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 light-blocking film is as follows:

[0097] S1: Weigh the black film raw materials according to the weight parts and mix them evenly to obtain the black film mixture. Weigh the white film raw materials according to the weight parts and mix them evenly to obtain the white film mixture. The mixing temperature is 100℃ and the mixing time is 20 minutes.

[0098] S2: Add the black film mixture and the white film mixture to the upper and lower molds of the composite film blow molding machine, respectively, perform composite blow molding, cool and shape, stretch 5 times laterally and 5 times longitudinally to obtain a black and white light-blocking film.

[0099] Comparative Example 2

[0100] The PE black and white light-blocking film of this embodiment uses the following raw materials by weight: 800g of low-density polyethylene, 10g of crosslinking 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 crosslinking 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 low-density polyethylene in the black film is 0.9 g / 10 min, purchased from Yanshan Petrochemical 5000S*, and the melt index of 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 light-blocking film is as follows:

[0103] S1: Weigh the black film raw materials according to the weight parts and mix them evenly to obtain the black film mixture. Weigh the white film raw materials according to the weight parts and mix them evenly to obtain the white film mixture. The mixing temperature is 100℃ and the mixing time is 20 minutes.

[0104] S2: Add the black film mixture and the white film mixture to the upper and lower molds of the composite film blow molding machine, respectively, perform composite blow molding, cool and shape, stretch 5 times laterally and 5 times longitudinally to obtain a black and white light-blocking film.

[0105] Performance testing

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

[0107] Test 2: The light-shielding performance of the PE black and white light-shielding film prepared in the example and comparative examples was tested using the light transmission box method in accordance with standard AATCC-148-79.

[0108] The results are summarized in Table 1.

[0109] Table 1

[0110] Tear strength (kN / m) Opacity (%) 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

[0111] In conjunction with Examples 1-3, Comparative Example 1, and Table 1, this application demonstrates that by using white flake mica powder as a filler for the white film and limiting the melt index of low-density polyethylene in the black and white films, the resulting black and white shading film exhibits good shading effect and high tear strength.

[0112] In conjunction with Examples 1 and 4 and Table 1, this application achieves better shrinkage coverage and higher tear strength by limiting the melt index difference between the black film and the white film.

[0113] In conjunction with Examples 1, 5-6, and 8 and Table 1, this application further limits the mesh size of the white flake mica powder and adds other fillers to make the black and white film shrink more stably after shaping, thereby further improving its strength performance.

[0114] In conjunction with Examples 1, 7-9, and Comparative Example 2, and with reference to Table 1, this application limits the mass ratio of modified white flake mica powder to polyethylene. The modified white flake mica powder has better compatibility in membrane materials, better bonding effect in black and white films, and higher tear strength.

[0115] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A PE black and white light-blocking film, characterized in that: The PE black and white light-blocking film includes a black film and a white film. The black film comprises the following raw materials in parts by weight: 80-100 parts low-density polyethylene, 1-1.5 parts crosslinking agent, 0.5-1.0 parts lubricant, 0.1-0.5 parts antioxidant, and 15-35 parts carbon black. The white film comprises the following raw materials in parts by weight: 80-100 parts low-density polyethylene, 1-1.5 parts crosslinking agent, 0.5-1.0 parts lubricant, 0.1-0.5 parts antioxidant, and 5-20 parts white filler, wherein the white filler includes white flaky mica powder. The black film contains low-density polyethylene. The melt index of the low-density polyethylene in the white film is 0.7-0.9 g / 10 min, and the melt index of the low-density polyethylene in the black film is 0.38-0.42 g / 10 min. The melt index of the low-density polyethylene in the black film is 0.4-0.5 g / 10 min higher than that in the white film. The mesh size of the white flake mica powder is 60-120 mesh. The white flake mica powder is modified with an epoxy silane coupling agent. The mass ratio of the epoxy silane coupling agent modified white flake mica powder to the low-density polyethylene in the white film is 1:(10-12).

2. The PE black and white light-blocking 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.

3. The PE black and white light-blocking film according to claim 1, characterized in that: The white filler also includes one or more of titanium dioxide, silica, talc, and calcium carbonate.

4. The PE black and white light-blocking film according to claim 1, characterized in that: The preparation steps of the epoxy silane coupling agent modified white flaky mica powder include: adding white flaky mica powder to an ethanol aqueous solution, then adding an epoxy silane coupling agent, stirring evenly, heating, reacting, filtering, and drying to obtain epoxy silane coupling agent modified white flaky mica powder.

5. A method for preparing the PE black and white light-blocking film according to any one of claims 1-4, characterized in that: The preparation method includes the following steps: S1: Weigh the black film raw materials according to the weight parts and mix them evenly to obtain the black film mixture; weigh the white film raw materials according to the weight parts and mix them evenly to obtain the white film mixture. S2: Add the black film mixture and the white film mixture to the upper and lower molds of the composite film blow molding machine, respectively, perform composite blow molding, cooling, stretching and shaping to obtain a black and white light-blocking film.

6. The method for preparing the PE black and white light-blocking film according to claim 5, characterized in that: The mixing temperature is 100-130°C, and the mixing time is 10-25 minutes.