A shrink film
By using a high proportion of metallocene polyethylene, cycloolefin-based copolymer and chlorinated polyethylene in the core layer of the shrink film, and adding a modifier, the existing shrink film has been solved, and better mechanical properties and transparency have been achieved.
Patent Information
- Application Number
- CN202510150055.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-11
- Publication Date
- 2025-04-22
- Estimated Expiration
- 2045-02-11
AI Technical Summary
The existing shrink film has a large thickness and poor transparency, which cannot meet the needs of thinning and improving transparency.
A shrink film consisting of an outer layer, a core layer and an inner layer is designed. The core layer contains a high proportion of metallocene polyethylene, cycloolefin copolymers and chlorinated polyethylene, and modifiers such as polymethyl methacrylate, glyceryl monostearate, polyethylene wax and polytetrafluoroethylene are added.
It effectively improves the mechanical properties and transparency of the shrink film, meets the needs of thinning and improving transparency, and improves shrinkage, tensile and impact resistance.
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Abstract
Description
Technical Field
[0001] The invention relates to the technical field of shrinkage films, in particular to a shrinkage film. Background Art
[0002] Shrink film is a widely used packaging method with its unique advantages. Using shrink film to wrap items can keep the appearance of the wrapped items beautiful, and at the same time can wrap the items tightly, and can be used to wrap irregular shaped items. Shrink film has high puncture resistance, good shrinkage and certain shrinkage stress. It is mainly used in the sales and transportation of various products to stabilize, cover and protect the products. Shrink packaging not only looks beautiful, but also has the functions of moisture-proof, dust-proof, loose-proof, anti-theft and collection.
[0003] At present, most polyethylene heat shrinkable films on the market are processed and produced using high-pressure polyethylene alone or a blend of high-density polyethylene and high-pressure polyethylene. Although the shrinkage film has high shrinkage and mechanical properties, the film products are relatively thick, usually more than 100μm, which cannot meet the current demand for thinning shrinkage films; in addition, the current shrinkage film has poor transparency, which affects the appearance of the goods after packaging. Summary of the invention
[0004] The purpose of the present invention is to overcome the defects in the prior art and provide a shrink film which can effectively solve the above problems in the prior art.
[0005] To achieve the above purpose, the technical solution of the present invention is to design a shrink film, which consists of an outer layer, a core layer and an inner layer.
[0006] The inner layer and the outer layer both include linear low-density polyethylene, medium-density polyethylene, chlorinated polyethylene and metallocene polyethylene;
[0007] The core layer includes metallocene polyethylene, cycloolefin copolymer, chlorinated polyethylene and a modifier; the weight proportion of the metallocene polyethylene, cycloolefin copolymer and chlorinated polyethylene in the core layer is at least 80% or more; the weight ratio of the metallocene polyethylene, cycloolefin copolymer and chlorinated polyethylene in the core layer is 2-6:1-4:1; specifically, the weight ratio of the metallocene polyethylene, cycloolefin copolymer and chlorinated polyethylene in the core layer can be 3:2:1, 4:2:1, 4:3:1, 4:2.5:1.
[0008] The modifier includes at least one or more of polymethyl methacrylate, glyceryl monostearate, polyethylene wax and polytetrafluoroethylene.
[0009] Furthermore, the cycloolefin copolymer is COC.
[0010] Furthermore, the modifier includes polymethyl methacrylate, glyceryl monostearate, polyethylene wax and polytetrafluoroethylene, and the weight ratio of polymethyl methacrylate, glyceryl monostearate, polyethylene wax and polytetrafluoroethylene is 1-5:2-10:0.5-2:1-5.
[0011] Preferably, the weight ratio of polymethyl methacrylate, glyceryl monostearate, polyethylene wax and polytetrafluoroethylene is 2:4:1:2.
[0012] Furthermore, the weight proportion of the metallocene polyethylene, cycloolefin copolymer and chlorinated polyethylene in the core layer is 85-90%. Preferably, the weight proportion of the metallocene polyethylene in the core layer is greater than that of the cycloolefin copolymer.
[0013] Furthermore, the weight ratio of the metallocene polyethylene, the cycloolefin copolymer and the chlorinated polyethylene in the core layer is 4:2.5:1.
[0014] Furthermore, in parts by weight, the inner layer and the outer layer each include 15-25 parts of linear low-density polyethylene, 10-15 parts of medium-density polyethylene, 10-20 parts of chlorinated polyethylene and 60-80 parts of metallocene polyethylene.
[0015] Furthermore, the core layer comprises, by weight, 20-35 parts of metallocene polyethylene, 20-30 parts of cycloolefin copolymer, 5-10 parts of chlorinated polyethylene, 1-5 parts of polymethyl methacrylate, 2-10 parts of glyceryl monostearate, 0.5-2 parts of polyethylene wax and 1-5 parts of polytetrafluoroethylene.
[0016] Further, the inner layer and the outer layer each include 20 parts of linear low-density polyethylene, 12 parts of medium-density polyethylene, 15 parts of chlorinated polyethylene and 75 parts of metallocene polyethylene by weight;
[0017] The core layer comprises 32 parts of metallocene polyethylene, 20 parts of cycloolefin copolymer, 8 parts of chlorinated polyethylene, 2 parts of polymethyl methacrylate, 4 parts of glycerol monostearate, 1 part of polyethylene wax and 2 parts of polytetrafluoroethylene.
[0018] Furthermore, the shrink film has a thickness of 40-60 μm, the thickness ratio of the outer layer, the core layer and the inner layer is 1:1-5:1, and the thickness of the outer layer is 5-15 μm. Preferably, the thickness ratio of the outer layer, the core layer and the inner layer is 1:2:1.
[0019] Preferably, the thickness of the inner layer and the outer layer are both 12 μm, the thickness of the core layer is 24 μm, and the thickness of the shrink film is 48 μm.
[0020] Furthermore, the preparation method of the shrink film is:
[0021] 1) Weigh the raw materials of the inner layer, outer layer and core layer according to the preset weight portions;
[0022] 2) After mixing the raw materials of the inner layer, outer layer and core layer, they are placed in an internal mixer and heated at 140-170°C to obtain plasticized hot materials;
[0023] 3) The three layers of plasticized hot materials are extruded on three single-screw extruders respectively and extruded through a three-layer co-extrusion die head, the temperature of the co-extrusion die head is 180-220°C, and the shrink film is obtained by extrusion blow molding and automatic air cooling at overtemperature.
[0024] The shrink film of the present invention can be used to prepare packaging materials.
[0025] The advantages and beneficial effects of the present invention are:
[0026] (1) By adding metallocene polyethylene, cycloolefin copolymer and chlorinated polyethylene in specific ratios and proportions to the core layer of the present invention, the mechanical properties of the shrinkage rate can be effectively improved, and the shrinkage rate reduction requirements can be met at the same time; in addition, by adding a modifier composed of polymethyl methacrylate, glyceryl monostearate, polyethylene wax and polytetrafluoroethylene to the core layer of the present invention, the yellow index and light transmittance of the shrinkage film can be effectively improved;
[0027] (2) When the weight proportion of metallocene polyethylene, cycloolefin copolymer and chlorinated polyethylene in the core layer is 85-90%, and the weight ratio of metallocene polyethylene, cycloolefin copolymer and chlorinated polyethylene in the core layer is 4:2.5:1, the shrinkage performance, tensile strength and impact resistance of the shrinkage film prepared by the metallocene polyethylene, cycloolefin copolymer and chlorinated polyethylene are good. It can be seen that metallocene polyethylene, cycloolefin copolymer and chlorinated polyethylene have a good synergistic effect on improving the mechanical properties of the shrinkage film. DETAILED DESCRIPTION
[0028] The specific implementation of the present invention is further described below in conjunction with the examples. The following examples are only used to more clearly illustrate the technical solutions of the present invention, and cannot be used to limit the protection scope of the present invention.
[0029] The purchasers and brands of the raw materials in the embodiments and comparative examples are as follows:
[0030] Linear low-density polyethylene: brand FB2230, density 0.923 g / cm 3 , melt flow rate is 0.2g / 10min, Borealis Chemicals Ltd., UAE.
[0031] Medium density polyethylene: Model ELITE5538G, Dow Chemical.
[0032] Metallocene polyethylene: Model: Enable 4002, density: 0.940 g / cm 3 , melt flow rate is 0.21g / 10min, ExxonMobil Corporation, USA.
[0033] Cyclic olefin copolymer COC was purchased from Polyplastics of Japan with the brand number 8007F.
[0034] 1. Implementation
[0035] Embodiment 1:
[0036] A shrink film, consisting of an inner layer, a core layer and an outer layer, wherein:
[0037] 1) In terms of weight, the inner layer comprises 20 parts of linear low-density polyethylene, 12 parts of medium-density polyethylene, 15 parts of chlorinated polyethylene and 75 parts of metallocene polyethylene; the above raw materials are mixed evenly, added into an internal mixer, mixed at 145° C. for 5 minutes and then discharged to obtain the resin for the inner layer;
[0038] 2) The core layer comprises, by weight, 32 parts of metallocene polyethylene, 20 parts of cycloolefin copolymer, 8 parts of chlorinated polyethylene, 2 parts of polymethyl methacrylate, 4 parts of glycerol monostearate, 1 part of polyethylene wax and 2 parts of polytetrafluoroethylene; the above raw materials are premixed and added into an internal mixer, mixed at 145° C. for 5 minutes and then discharged to obtain a core layer resin; the cycloolefin copolymer is COC;
[0039] 3) In parts by weight, the outer layer comprises 20 parts of linear low-density polyethylene, 12 parts of medium-density polyethylene, 15 parts of chlorinated polyethylene and 75 parts of metallocene polyethylene; the above raw materials are mixed evenly, added into an internal mixer, mixed at 145° C. for 5 minutes and then discharged to obtain the resin for the outer layer;
[0040] 4) The three layers of hot resin are extruded on three single-screw extruders respectively, and then extruded through a three-layer co-extrusion die head at a temperature of 210° C. The heat shrinkable film is obtained by extrusion blow molding and automatic air cooling at overtemperature.
[0041] Among them, the thickness of the inner layer: the thickness of the core layer: the thickness of the outer layer = 1:2:1, the thickness of the inner layer and the outer layer are both 12 μm, the thickness of the core layer is 24 μm, and the thickness of the shrink film is 48 μm.
[0042] Comparative Example 1:
[0043] The only difference from Example 1 is that the core layer components are different, as follows:
[0044] In parts by weight, the core layer comprises: 60 parts of metallocene polyethylene, 2 parts of polymethyl methacrylate, 4 parts of glyceryl monostearate, 1 part of polyethylene wax and 2 parts of polytetrafluoroethylene.
[0045] Comparative Example 2:
[0046] The only difference from Example 1 is that the core layer components are different, as follows:
[0047] In parts by weight, the core layer comprises: 60 parts of cycloolefin copolymer, 2 parts of polymethyl methacrylate, 4 parts of glyceryl monostearate, 1 part of polyethylene wax and 2 parts of polytetrafluoroethylene.
[0048] Comparative Example 3:
[0049] The only difference from Example 1 is that the core layer components are different, as follows:
[0050] In parts by weight, the core layer comprises: 60 parts of chlorinated polyethylene, 2 parts of polymethyl methacrylate, 4 parts of glyceryl monostearate, 1 part of polyethylene wax and 2 parts of polytetrafluoroethylene.
[0051] Comparative Example 4:
[0052] The only difference from Example 1 is that the core layer components are different, as follows:
[0053] In parts by weight, the core layer comprises 20 parts of metallocene polyethylene, 20 parts of cycloolefin copolymer, 8 parts of chlorinated polyethylene, 2 parts of polymethyl methacrylate, 4 parts of glyceryl monostearate, 1 part of polyethylene wax and 2 parts of polytetrafluoroethylene.
[0054] Comparative Example 5:
[0055] The only difference from Example 1 is that the core layer components are different, as follows:
[0056] In parts by weight, the core layer comprises 40 parts of metallocene polyethylene, 25 parts of cycloolefin copolymer, 10 parts of chlorinated polyethylene, 2 parts of polymethyl methacrylate, 4 parts of glycerol monostearate, 1 part of polyethylene wax and 2 parts of polytetrafluoroethylene.
[0057] Comparative Example 6:
[0058] The only difference from Example 1 is that the core layer components are different, as follows:
[0059] In parts by weight, the core layer comprises 24 parts of metallocene polyethylene, 15 parts of cycloolefin copolymer, 6 parts of chlorinated polyethylene, 2 parts of polymethyl methacrylate, 4 parts of glycerol monostearate, 1 part of polyethylene wax and 2 parts of polytetrafluoroethylene.
[0060] Comparative Example 7:
[0061] The only difference from Example 1 is that the core layer components are different, as follows:
[0062] In parts by weight, the core layer comprises 32 parts of metallocene polyethylene, 20 parts of cycloolefin copolymer, 8 parts of chlorinated polyethylene, 0 parts of polymethyl methacrylate, 4 parts of glyceryl monostearate, 1 part of polyethylene wax and 2 parts of polytetrafluoroethylene.
[0063] Comparative Example 8:
[0064] The only difference from Example 1 is that the core layer components are different, as follows:
[0065] In parts by weight, the core layer comprises 32 parts of metallocene polyethylene, 20 parts of cycloolefin copolymer, 8 parts of chlorinated polyethylene, 2 parts of polymethyl methacrylate, 4 parts of glyceryl monostearate, 1 part of polyethylene wax and 0 parts of polytetrafluoroethylene.
[0066] Comparative Example 9:
[0067] The only difference from Example 1 is that the core layer components are different, as follows:
[0068] In parts by weight, the core layer comprises 32 parts of metallocene polyethylene, 20 parts of cycloolefin copolymer, 8 parts of chlorinated polyethylene, 2 parts of polymethyl methacrylate, 0 parts of glyceryl monostearate, 1 part of polyethylene wax and 2 parts of polytetrafluoroethylene.
[0069] Comparative Example 10:
[0070] The only difference from Example 1 is that the core layer components are different, as follows:
[0071] In parts by weight, the core layer comprises 32 parts of metallocene polyethylene, 20 parts of cycloolefin copolymer, 8 parts of chlorinated polyethylene, 2 parts of polymethyl methacrylate, 4 parts of glyceryl monostearate, 0 parts of polyethylene wax and 2 parts of polytetrafluoroethylene.
[0072] Comparative Example 11:
[0073] The only difference from Example 1 is that the core layer components are different, as follows:
[0074] In parts by weight, the core layer includes 32 parts of metallocene polyethylene, 20 parts of cycloolefin copolymer, and 8 parts of chlorinated polyethylene.
[0075] (II) Performance test methods and results
[0076] (1) Performance test method
[0077] Shrinkage rate: measured in accordance with the provisions of standard GB / T 13519-2016;
[0078] Tensile strength: measured according to GB / T 13735-2017;
[0079] Dart impact performance: tested in accordance with GB 9639.1-2008;
[0080] Light transmittance: tested in accordance with the provisions of GB / T 15267-94;
[0081] Yellowness index: tested in accordance with the provisions of HG-T3862-2006.
[0082] (2) Performance test results
[0083] The performance test results of the embodiments and comparative examples are as follows:
[0084]
[0085] From the performance test results of Example 1 and Comparative Examples 1-6, it can be seen that when the weight proportion of metallocene polyethylene, cycloolefin copolymer, and chlorinated polyethylene in the core layer is 85-90%, and the weight ratio of metallocene polyethylene, cycloolefin copolymer, and chlorinated polyethylene in the core layer is 4:2.5:1, the shrinkage performance, tensile strength, and impact resistance of the shrinkage film prepared therefrom are all good. It can be seen that metallocene polyethylene, cycloolefin copolymer, and chlorinated polyethylene have a good synergistic effect on improving the mechanical properties of the shrinkage film.
[0086] It can be seen from the performance test results of Example 1 and Comparative Examples 7-10 that when the modifier in the core layer is polymethyl methacrylate, glyceryl monostearate, polyethylene wax and polytetrafluoroethylene, the shrinkage yellow index and light transmittance can be effectively improved.
[0087] By adding metallocene polyethylene, cycloolefin copolymer and chlorinated polyethylene in specific ratios and proportions to the core layer of the present invention, the mechanical properties of the shrinkage rate can be effectively improved, and the demand for shrinkage thinning can be met at the same time; in addition, by adding a modifier composed of polymethyl methacrylate, glyceryl monostearate, polyethylene wax and polytetrafluoroethylene to the core layer of the present invention, the yellow index and light transmittance of the shrinkage film can be effectively improved.
[0088] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.
Claims
1. A shrink film, consisting of an outer layer, a core layer and an inner layer, characterized in that: The inner layer and the outer layer both include linear low-density polyethylene, medium-density polyethylene, chlorinated polyethylene and metallocene polyethylene; The core layer comprises metallocene polyethylene, cycloolefin copolymer, chlorinated polyethylene and a modifier; The modifier comprises polymethyl methacrylate, glyceryl monostearate, polyethylene wax and polytetrafluoroethylene, and the weight ratio of the polymethyl methacrylate, glyceryl monostearate, polyethylene wax and polytetrafluoroethylene is 1-5:2-10:0.5-2:1-5; The weight proportion of the metallocene polyethylene, cycloolefin copolymer and chlorinated polyethylene in the core layer is 85-90%; the weight ratio of the metallocene polyethylene, cycloolefin copolymer and chlorinated polyethylene in the core layer is 4:2.5:
1.
2. A shrink film according to claim 1, characterized in that: In parts by weight, the inner layer and the outer layer each include 15-25 parts of linear low-density polyethylene, 10-15 parts of medium-density polyethylene, 10-20 parts of chlorinated polyethylene and 60-80 parts of metallocene polyethylene.
3. A shrink film according to claim 2, characterized in that: In parts by weight, the core layer comprises 20-35 parts of metallocene polyethylene, 20-30 parts of cycloolefin copolymer, 5-10 parts of chlorinated polyethylene, 1-5 parts of polymethyl methacrylate, 2-10 parts of glyceryl monostearate, 0.5-2 parts of polyethylene wax and 1-5 parts of polytetrafluoroethylene.
4. A shrink film according to claim 3, characterized in that: In parts by weight, the inner layer and the outer layer each include 20 parts of linear low-density polyethylene, 12 parts of medium-density polyethylene, 15 parts of chlorinated polyethylene and 75 parts of metallocene polyethylene; The core layer comprises 32 parts of metallocene polyethylene, 20 parts of cycloolefin copolymer, 8 parts of chlorinated polyethylene, 2 parts of polymethyl methacrylate, 4 parts of glycerol monostearate, 1 part of polyethylene wax and 2 parts of polytetrafluoroethylene.
5. A shrink film according to claim 1, characterized in that: The thickness of the shrink film is 40-60 μm, the thickness ratio of the outer layer, the core layer and the inner layer is 1:1-5:1; the thickness of the outer layer is 5-15 μm.
6. A shrink film according to any one of claims 1 to 5 which can be used to prepare packaging materials.
Citation Information
Patent Citations
Heat shrinkable film composition
CN110757924A
Metallocene polyethylene thermal shrinkage film and composition and preparation method thereof
CN117567809A