CN111100413B - PE shrink film - Google Patents

Abstract

The invention provides a PE shrink film which is formed by blending and film blowing raw materials, wherein the raw materials comprise, by weight, 1-10% of PET, 90-98% of modified PE and 0-2% of a compatilizer, and the raw materials of the modified PE comprise a PE material, a cross-linking agent and a methyl methacrylate monomer. The modified PE shrink film provided by the invention has low crystallinity, and is beneficial to enhancing the tensile property and the shrinkage property of the PE shrink film. The methyl methacrylate monomer in the modified PE and the polyethylene are subjected to a grafting reaction, so that the affinity of the polyethylene and other materials can be improved, the modified PE and the PET have good compatibility, the delamination of the modified PE and the PET during coextrusion can be avoided, and a PET shrink film prepared by mixing the modified PE and the PET has good shrinkage and high tensile strength.

Description

PE shrink film

Technical Field

The invention relates to the technical field of PE films, in particular to a PE shrink film.

Background

The PE shrink film is an industrial packaging film product, has the characteristics of recovery, no toxicity, no odor, good mechanical property and the like, is used for manual winding films, can also be used for machine winding films, and can be widely applied to centralized packaging of various goods. The polyethylene shrink film is a material with good toughness, is widely suitable for the integral assembly packaging of products such as wines, pop-top cans, mineral water, various beverages, cloth and the like, and has the advantages of good flexibility, strong impact resistance and tear resistance and difficult damage.

At present, the existing PE shrink film is made of general PE material, and has high crystallinity, low tensile strength and poor shrink performance, so it is necessary to provide a PE shrink film with good shrink performance and high tensile strength, and the film thickness can be reduced to achieve the effect of light weight on the premise of ensuring the use effect.

Disclosure of Invention

The invention aims to provide a PE shrink film with good shrinkability and high tensile strength.

In order to achieve the purpose, the invention provides a PE shrink film which is formed by blending and blowing raw materials, wherein the raw materials comprise, by weight, 1-10% of PET, 90-98% of modified PE and 0-2% of a compatilizer, and the modified PE is obtained by modifying PE by a monomer containing methyl methacrylate.

In the PE shrink film provided by the invention, the modified PE obtained by modifying PE by the monomer containing methyl methacrylate has low crystallinity, and is beneficial to enhancing the shrink performance of the PE shrink film. The methyl methacrylate monomer in the modified PE and the polyethylene are subjected to a grafting reaction, so that the affinity of the polyethylene and other materials can be improved, the modified PE and the PET have good compatibility, the delamination of the modified PE and the PET during coextrusion can be avoided, and a PET shrink film prepared by mixing the modified PE and the PET has good shrinkage and high tensile strength.

Preferably, the modified PE is obtained by crosslinking and modifying PE by a monomer containing methyl methacrylate and a crosslinking agent, wherein the monomer accounts for 5-20% of the weight of the PE, the monomer comprises 0-30% of acrylonitrile and 30-70% of methyl methacrylate by weight percentage, and the crosslinking agent accounts for 0.1-0.5% of the weight of the PE. The double bond contained in the acrylonitrile makes the acrylonitrile easily generate polymerization reaction with other organic compounds, and the addition of the acrylonitrile in the modified PE is beneficial to enhancing the tear strength of the modified PE. The cross-linking agent initiates the reaction of acrylonitrile, methyl methacrylate monomer and PE to finally obtain the modified PE with low crystallinity, high tensile strength and good shrinkage effect.

Preferably, the cross-linking agent is dibenzoyl peroxide (BPO).

Preferably, the preparation method of the modified PE comprises the following steps:

(1) dissolving the PE material in toluene;

(2) adding the cross-linking agent to react with the methyl methacrylate or adding the cross-linking agent, the methyl methacrylate and the acrylonitrile to react;

(3) suction filtration was carried out with acetone.

Preferably, the dissolving temperature in the step (1) is 75-85 ℃, and the dissolving time is 2-4 h.

Preferably, in the step (2), the reaction temperature is 90-100 ℃, and the reaction time is 20-28 h.

Preferably, the density of the PE material is 0.914-0.920 g/cm³The melt index is 0.8-1.2 g/10 min.

Preferably, the compatilizer is a maleic anhydride grafted compatilizer, and further, the maleic anhydride grafted compatilizer is selected from one or more of SEBS-g-MAH, HDPE-g-MAH and POE-g-MAH. SEBS-g-MAH is maleic anhydride graft of hydrogenated styrene-butadiene-styrene triblock copolymer, HDPE-g-MAH is maleic anhydride graft of high density polyethylene, and POE-g-MAH is maleic anhydride graft of ethylene-octene copolymer.

The invention also provides a preparation method of the PE shrink film, which comprises the following steps:

(1) extruding: uniformly mixing the raw materials in the PET shrink film, and conveying the mixture to an extruder;

(2) film blowing: preparing a PE shrink film by one-time blowing through an extruder;

(3) cooling;

(4) traction;

(5) and (4) coiling.

Detailed Description

The technical solutions of the present invention are further illustrated by the following specific embodiments, but the present invention is not limited thereto.

Example 1:

the PE shrink film is prepared from 2% of PET and 98% of modified PE, wherein the modified PE is prepared by modifying the PE by a cross-linking agent accounting for 0.1% of the weight of the PE and methyl methacrylate accounting for 5% of the weight of the PE, and the density of the PE is 0.918g/cm³The melt index was 1.0 and the weight of PE was 500 parts.

The preparation method of the modified PE comprises the following steps:

(1) dissolving PE in toluene for 2-4 h, wherein the dissolving temperature is 75-85 ℃, specifically in the embodiment, the dissolving temperature is 80 ℃, and the dissolving time is 3 h;

(2) adding BPO and methyl methacrylate to react, wherein the reaction temperature is 90-100 ℃, the reaction time is 20-28 h, and specifically in the embodiment, the water bath is 95 ℃ and 24 h;

(3) after the reaction is finished, the product is filtered by using acetone.

Example 2

The PE shrink film is prepared from 10% of PET and 90% of modified PE, wherein the modified PE is prepared by modifying the PE by using a crosslinking agent accounting for 0.5% of the weight of the PE and a monomer accounting for 20% of the weight of the PE (the weight of acrylonitrile in the monomer is 30%, and the weight of methyl methacrylate in the monomer is 70%), and the density of the PE is 0.918g/cm³The melt index was 1.0 and the weight of PE was 500 parts.

Examples 2 to 7 except that the components and the mixture ratio listed in table 1 are different, the other formulation parameters and the preparation method of the modified PE are the same as those of example 1, and it should be noted that the compatibilizer in all the examples is maleic anhydride grafted compatibilizer, specifically SEBS-g-MAH.

Table 1 compositions and proportions of the examples

Comparative example 1

The PE shrink film is a single layer shrink film composed of 10% PET and 90% PE.

In all examples and comparative examples, the PE shrink films were prepared by the following method:

(1) extruding: uniformly mixing the raw materials of the PE shrink film according to the proportion (if the raw materials contain the compatilizer, mixing the compatilizer, PET and modified PE together), and conveying the mixture to an extruder;

(2) film blowing: preparing a PE shrink film by one-time blowing of an extruder, wherein the melt flow rate of each raw material is 1.0g/10 min;

(3) and (3) cooling: the cooling time was 70 seconds;

(4) traction;

(5) and (4) coiling.

The PE shrink films with the thickness of 0.04mm prepared in examples 1-7 and comparative example 1 were measured for longitudinal shrinkage and transverse shrinkage according to the specification of GB/T13519-2016, for longitudinal elongation at break and transverse elongation at break according to the specification of GB/T1040.1-2006, for tensile strength according to the specification of GB/T13735-2017, and for dart impact performance according to the specification of GB 9639.1-2008.

The test results of examples 1 to 7 and comparative example 1 are shown in Table 2:

TABLE 2 Performance test data for each of the examples and comparative examples

As can be seen from Table 2, the shrinkage rates (longitudinal shrinkage rate and transverse shrinkage rate) are all relatively similar, ensuring the shrinkage effect of the shrink film in use, and the results of longitudinal rupture rate, transverse rupture rate, tensile strength and dart impact strength are all better than those of the comparative examples. The modified PE in the PE shrink film provided by the invention is helpful for enhancing the tensile property and the shrink property of the PE shrink film.

Example 3 the test results for example 3 were better than example 4 than for example 4, probably due to the addition of a compatibilizer in example 3 that helps the PET to be more compatible with the modified PE, thus improving the overall performance of the PE shrink film.

Example 4 compared to example 5, the test results of example 4 were better than those of example 5, probably due to the addition of acrylonitrile to the modified PE raw material in example 4, and the double bond contained in acrylonitrile contributes to enhancing the tensile properties of modified PE.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present application. Various modifications to these embodiments (including but not limited to PET, modified PE, levels of compatibilizing agent, specific nature of compatibilizing agent, modified PE manufacturing parameters, PE shrink film manufacturing parameters) will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles disclosed herein.

Claims (9)

1. A PE shrink film characterized by: the modified PE is prepared by crosslinking and modifying PE by a monomer containing methyl methacrylate and a crosslinking agent, wherein the monomer accounts for 5-20% of the weight of the PE, the monomer accounts for 20-30% of acrylonitrile and 30-70% of methyl methacrylate, and the crosslinking agent accounts for 0.1-0.5% of the weight of the PE.

2. The PE shrink film of claim 1, wherein: the cross-linking agent is dibenzoyl peroxide.

3. The PE shrink film of claim 1, wherein the modified PE is prepared by a process comprising:

(1) dissolving the PE in toluene;

(2) adding the cross-linking agent, the methyl methacrylate and the acrylonitrile for reaction;

(3) suction filtration was carried out with acetone.

4. The PE shrink film according to claim 3, wherein the dissolution temperature in the step (1) is 75 to 85 ℃, and the dissolution time is 2 to 4 hours.

5. The PE shrink film according to claim 3, wherein in the step (2), the reaction temperature is 90-100 ℃, and the reaction time is 20-28 h.

6. The PE shrink film of claim 1, wherein the PE has a density of from 0.914 to 0.920g/cm³The melt index is 0.8-1.2 g/10 min.

7. The PE shrink film of claim 1, wherein the compatibilizer is a maleic anhydride grafted compatibilizer.

8. The PE shrink film of claim 7, wherein the maleic anhydride grafted compatibilizer is selected from one or more of SEBS-g-MAH, HDPE-g-MAH, and POE-g-MAH.

9. The method of producing a PE shrink film according to any one of claims 1 to 8, comprising:

(1) extruding: uniformly mixing the raw materials in the PE shrink film, and conveying the mixture to an extruder;

(2) film blowing: preparing a PE shrink film by one-time blowing through an extruder;

(3) cooling;

(4) traction;

(5) and (4) coiling.