A high-barrier degradable polyethylene composite film, bag, and method of making

Abstract

The application relates to the technical field of polyethylene composite films, and provides a high-barrier degradable polyethylene composite film, a bag and a preparation method. The high-barrier degradable polyethylene composite film is obtained by compounding a degradable polyethylene printing film and a high-barrier polyethylene heat-seal film. The high-barrier degradable polyethylene composite film has excellent mechanical properties, high transparency, good printability, high oxygen resistance and high water resistance, and can be effectively degraded under the conditions of light, heat and oxygen and composting, and can be completely degraded into carbon dioxide and water without generating microplastics. Therefore, the high-barrier degradable polyethylene composite film has wide application prospects and can be used as a packaging bag for food, daily chemical products and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of polyethylene film, in particular to a high-barrier degradable polyethylene composite film, bag and preparation method. BACKGROUND

[0002] Polyethylene film is widely used in various industries, and can be used as shrink film, optical protective film, shopping bag, food packaging bag, etc. When polyethylene film is used as a packaging bag, it is required to have certain strength, not easy to be damaged during transportation, and not to cause leakage of the packaged contents. When polyethylene film is used as a food packaging bag, it is also required to have high barrier properties, including oxygen barrier and water barrier, etc., to avoid deterioration of the packaged contents. However, polyethylene film has good stability and is not easy to decompose, and waste PE film is difficult to be harmlessly treated. With the increase of global plastic usage, the pressure of plastic waste is increasing, and the environmental pollution problem caused by waste plastics is attracting more and more attention, and environmental protection and social responsibility require the world to change to sustainable development.

[0003] Degradable film refers to a film that can completely degrade into harmless substances under certain conditions. At present, degradable film is usually prepared from degradable material, but the current degradable film has low strength, poor barrier property, and also has the disadvantages of poor transparency, printing ink dropping, etc., and can only be used in fields such as shopping bags, garbage bags, etc. which have low requirements, and cannot be used in fields such as food, daily chemical products, etc. which have high requirements. SUMMARY

[0004] Therefore, the present application provides a high-barrier degradable polyethylene composite film, bag and preparation method. The high-barrier degradable polyethylene composite film provided by the present application has good mechanical properties, good barrier property, high transparency, no ink dropping during printing, and excellent degradability.

[0005] In order to achieve the above-mentioned application purposes, the present application provides the following technical solutions:

[0006] A high-barrier degradable polyethylene composite film is obtained by compounding a degradable polyethylene printing film and a high-barrier polyethylene heat-seal film;

[0007] The degradable polyethylene printing film comprises an outer layer, a middle layer and an inner layer;

[0008] The preparation raw materials of the outer layer and the inner layer of the degradable polyethylene printing film independently comprise, in mass fraction: 10-30 parts of medium density polyethylene, 30-70 parts of high density polyethylene, 15-40 parts of medium density metallocene polyethylene, 1.5-2.5 parts of degradable masterbatch, and 0.5-1 part of processing aid;

[0009] The preparation raw materials of the middle layer of the degradable polyethylene printing film include, in mass fraction: 10-40 parts of first medium density metallocene polyethylene, 10-30 parts of second medium density metallocene polyethylene, 30-85 parts of high-strength low-density metallocene polyethylene, 1.5-2.5 parts of degradation master batch, and 0.5-1 part of processing aid;

[0010] The high-barrier polyethylene heat-seal film includes an outer layer, a middle layer and an inner layer;

[0011] The preparation raw materials of the outer layer of the high-barrier polyethylene heat-seal film include, in mass fraction: 10-30 parts of low-density polyethylene, 15-40 parts of low-density metallocene polyethylene, 20-75 parts of linear low-density polyethylene, 1.5-2.5 parts of degradation master batch, and 0.5-1 part of processing aid;

[0012] The preparation raw materials of the middle layer of the high-barrier polyethylene heat-seal film include, in mass fraction: 10-30 parts of low-density polyethylene, 10-50 parts of linear low-density polyethylene, 30-80 parts of low-density metallocene polyethylene, 1.5-2.5 parts of degradation master batch, and 0.5-1 part of processing aid;

[0013] The preparation raw materials of the inner layer of the high-barrier polyethylene heat-seal film include, in mass fraction: 10-25 parts of low-density polyethylene, 30-80 parts of low-density metallocene polyethylene, 20-60 parts of ultra-low-density metallocene polyethylene, 1.5-2.5 parts of degradation master batch, and 0.5-1 part of processing aid.

[0014] Preferably, in the preparation raw materials of the outer layer and the inner layer of the degradable polyethylene printing film: the melt index of the medium density polyethylene is 2.5-3.5 g / 10 min, and the density is 0.925-0.940 g / cm 3 ; the melt index of the high-density polyethylene is 0.3-1.5 g / 10 min, and the density is 0.955-0.970 g / cm 3 ; the melt index of the medium density metallocene polyethylene is 0.2-1.0 g / 10 min, and the density is 0.925-0.940 g / cm 3 ;

[0015] In the preparation raw materials of the middle layer of the degradable polyethylene printing film: the melt index of the first medium density metallocene polyethylene is 0.2-1.0 g / 10 min, and the density is 0.935-0.945 g / cm 3 ; the melt index of the second medium density metallocene polyethylene is 2.0-3.0 g / 10 min, and the density is 0.930-0.940 g / cm 3 ; the melt index of the high-strength low-density metallocene polyethylene is 0.2-1.0 g / 10 min, and the density is 0.910-0.920 g / cm 3 .

[0016] Preferably, the raw material for preparing the outer layer of the high-barrier polyethylene heat-seal film has: a low-density polyethylene with a melt index of 1.5-2.5 g / 10 min and a density of 0.920-0.930 g / cm 3 ; a low-density metallocene polyethylene with a melt index of 1.5-2.5 g / 10 min and a density of 0.908-0.920 g / cm 3 ; a linear low-density polyethylene with a melt index of 1.5-2.5 g / 10 min and a density of 0.910-0.925 g / cm 3 ;

[0017] The raw material for preparing the middle layer of the high-barrier polyethylene heat-seal film has: a low-density polyethylene with a melt index of 1.5-2.5 g / 10 min and a density of 0.920-0.930 g / cm 3 ; a linear low-density polyethylene with a melt index of 1.5-2.5 g / 10 min and a density of 0.910-0.925 g / cm 3 ; a low-density metallocene polyethylene with a melt index of 0.5-2.0 g / 10 min and a density of 0.910-0.925 g / cm 3 ;

[0018] The raw material for preparing the inner layer of the high-barrier polyethylene heat-seal film has: a low-density polyethylene with a melt index of 1.5-2.5 g / 10 min and a density of 0.920-0.930 g / cm 3 ; a low-density metallocene polyethylene with a melt index of 0.3-1.5 g / 10 min and a density of 0.900-0.915 g / cm 3 ; an ultra-low-density metallocene polyethylene with a melt index of 0.5-1.8 g / 10 min and a density of 0.890-0.915 g / cm 3 .

[0019] Preferably, the melt index of the degradation master batch used for preparing the outer layer, the middle layer and the inner layer of the degradable polyethylene printing film and the high-barrier polyethylene heat-seal film is 46-55 g / 10 min, and the density is 0.920-0.940 g / cm 3 ; the melt index of the processing aid is 1.5.0-2.8 g / 10 min, and the density is 0.910-0.920 g / cm 3 .

[0020] Preferably, the raw material for preparing the outer layer and the inner layer of the degradable polyethylene printing film has: a medium-density polyethylene with a brand of 151BW, a high-density polyethylene with a brand of 8300, and a medium-density metallocene polyethylene with a brand of 3505MA;

[0021] The first middle density metallocene polyethylene has a brand of 4009, the second middle density metallocene polyethylene has a brand of 2036P, and the high-strength low-density metallocene polyethylene has a brand of XP6056ML;

[0022] The low-density polyethylene has a brand of 2420H, the low-density metallocene polyethylene has a brand of 1520, and the linear low-density polyethylene has a brand of 7042;

[0023] The low-density polyethylene has a brand of 2420H, the linear low-density polyethylene has a brand of 201XV, and the low-density metallocene polyethylene has a brand of 1018BN;

[0024] The low-density polyethylene has a brand of 2426H, the low-density metallocene polyethylene has a brand of AT6202, and the ultra-low-density metallocene polyethylene has a brand of SP0510H;

[0025] The degradation master batch used in the outer layer, the middle layer and the inner layer of the degradable polyethylene printing film and the outer layer, the middle layer and the inner layer of the high-barrier polyethylene heat-seal film has a brand of TRF-57, and the processing aid has a brand of PA0895LD.

[0026] Preferably, the thickness of the degradable polyethylene printing film is 30-80 μm, and the thickness of the high-barrier degradable polyethylene heat-seal film is 40-100 μm.

[0027] In the degradable polyethylene printing film, the mass fraction of the outer layer is 20-30%, the mass fraction of the middle layer is 40-60%, and the mass fraction of the inner layer is 20-30%.

[0028] In the high-barrier degradable polyethylene heat-seal film, the mass fraction of the outer layer is 25-30%, the mass fraction of the middle layer is 40-50%, and the mass fraction of the inner layer is 25-30%.

[0029] The application further provides a preparation method of the high-barrier degradable polyethylene composite film.

[0030] The preparation raw materials of the outer layer, the middle layer and the inner layer of the degradable polyethylene printing film are subjected to three-layer co-extrusion blown film to obtain the degradable polyethylene printing film.

[0031] The preparation raw materials of the outer layer, the middle layer and the inner layer of the high-barrier degradable polyethylene heat-seal film are subjected to three-layer co-extrusion blown film to obtain the high-barrier degradable polyethylene heat-seal film.

[0032] The degradable polyethylene printing film and the high-barrier degradable polyethylene heat-seal film are compounded by using an adhesive, and the high-barrier degradable polyethylene composite film is obtained after curing.

[0033] Preferably, before the degradable polyethylene printing film and the high-barrier degradable polyethylene heat-seal film are compounded, printing is further performed on the surface of the degradable polyethylene printing film.

[0034] Preferably, the temperature of the curing is 35-45 DEG C, and the time is 24-48 h.

[0035] The application further provides a high-barrier degradable polyethylene composite bag prepared from the high-barrier degradable polyethylene composite film, wherein the high-barrier degradable polyethylene composite film is the high-barrier degradable polyethylene composite film described in the above scheme or prepared by the preparation method described in the above scheme.

[0036] The application provides a high-barrier degradable polyethylene composite film, which is obtained by compounding a degradable polyethylene printing film and a high-barrier polyethylene heat-seal film; the degradable polyethylene printing film comprises an outer layer, a middle layer and an inner layer; the preparation raw materials of the outer layer and the inner layer of the degradable polyethylene printing film independently comprise, in mass fraction, 10-30 parts of medium-density polyethylene, 30-70 parts of high-density polyethylene, 15-40 parts of medium-density metallocene polyethylene, 1.5-2.5 parts of a degradation master batch and 0.5-1 part of a processing aid; the preparation raw materials of the middle layer of the degradable polyethylene printing film comprise, in mass fraction, 10-40 parts of first medium-density metallocene polyethylene, 10-30 parts of second medium-density metallocene polyethylene, 30-85 parts of high-strength low-density metallocene polyethylene, 1.5-2.5 parts of a degradation master batch and 0.5-1 part of a processing aid; the high-barrier polyethylene heat-seal film comprises an outer layer, a middle layer and an inner layer; the preparation raw materials of the outer layer of the high-barrier polyethylene heat-seal film comprise, in mass fraction, 10-30 parts of low-density polyethylene, 15-40 parts of low-density metallocene polyethylene, 20-75 parts of linear low-density polyethylene, 1.5-2.5 parts of a degradation master batch and 0.5-1 part of a processing aid; the preparation raw materials of the middle layer of the high-barrier polyethylene heat-seal film comprise, in mass fraction, 10-30 parts of low-density polyethylene, 10-50 parts of linear low-density polyethylene, 30-80 parts of low-density metallocene polyethylene, 1.5-2.5 parts of a degradation master batch and 0.5-1 part of a processing aid; and the preparation raw materials of the inner layer of the high-barrier polyethylene heat-seal film comprise, in mass fraction, 10-25 parts of low-density polyethylene, 30-80 parts of low-density metallocene polyethylene, 20-60 parts of ultra-low-density metallocene polyethylene, 1.5-2.5 parts of a degradation master batch and 0.5-1 part of a processing aid. The application strictly controls the preparation raw materials of the three layers of the degradable polyethylene printing film and the high-barrier polyethylene heat-seal film, ensures that the degradable polyethylene printing film and the high-barrier polyethylene heat-seal film both have high mechanical properties and transparency, the degradable polyethylene printing film has excellent printing performance and high ink layer adhesion, and the high-barrier polyethylene heat-seal film has excellent barrier properties and low water vapor transmission rate and oxygen transmission rate; meanwhile, the application also adds degradation master batches to the three layers of the degradable polyethylene printing film and the high-barrier polyethylene heat-seal film, so that the film has degradable performance. In summary, the application compounds the degradable polyethylene printing film and the high-barrier polyethylene heat-seal film, and the obtained high-barrier degradable polyethylene composite film has excellent mechanical properties, high transparency, good printability, high oxygen barrier and water barrier properties, and can be effectively degraded under the conditions of light, heat, oxygen and composting, and can be completely degraded into carbon dioxide and water without generating microplastics, so the high-barrier degradable polyethylene composite film provided by the application has a wide application prospect and can be used as a packaging bag for food, daily chemical products and the like. DETAILED DESCRIPTION

[0037] The application provides a high-barrier degradable polyethylene composite film, which is obtained by compounding a degradable polyethylene printing film and a high-barrier polyethylene heat-seal film;

[0038] The degradable polyethylene printing film comprises an outer layer, a middle layer and an inner layer;

[0039] The preparation raw materials of the outer layer and the inner layer of the degradable polyethylene printing film independently comprise, in mass fraction, 10-30 parts of medium-density polyethylene, 30-70 parts of high-density polyethylene, 15-40 parts of medium-density metallocene polyethylene, 1.5-2.5 parts of a degradation master batch and 0.5-1 part of a processing aid;

[0040] The preparation raw materials of the middle layer of the degradable polyethylene printing film comprise, in mass fraction, 10-40 parts of first medium-density metallocene polyethylene, 10-30 parts of second medium-density metallocene polyethylene, 30-85 parts of high-strength low-density metallocene polyethylene, 1.5-2.5 parts of a degradation master batch and 0.5-1 part of a processing aid;

[0041] The high-barrier polyethylene heat-seal film comprises an outer layer, a middle layer and an inner layer;

[0042] The preparation raw materials of the outer layer of the high-barrier polyethylene heat-seal film comprise, in mass fraction, 10-30 parts of low-density polyethylene, 15-40 parts of low-density metallocene polyethylene, 20-75 parts of linear low-density polyethylene, 1.5-2.5 parts of a degradation master batch and 0.5-1 part of a processing aid;

[0043] The preparation raw materials of the middle layer of the high-barrier polyethylene heat-seal film comprise, in mass fraction, 10-30 parts of low-density polyethylene, 10-50 parts of linear low-density polyethylene, 30-80 parts of low-density metallocene polyethylene, 1.5-2.5 parts of a degradation master batch and 0.5-1 part of a processing aid;

[0044] The preparation raw materials of the inner layer of the high-barrier polyethylene heat-seal film comprise, in mass fraction, 10-25 parts of low-density polyethylene, 30-80 parts of low-density metallocene polyethylene, 20-60 parts of ultra-low-density metallocene polyethylene, 1.5-2.5 parts of a degradation master batch and 0.5-1 part of a processing aid.

[0045] The high-barrier degradable polyethylene composite film of the application is described in detail below.

[0046] First, the components of the degradable polyethylene printing film are described.

[0047] The preparation raw materials of the outer layer of the degradable polyethylene printing film comprise, in mass fraction, 10-30 parts, preferably 15-25 parts, of medium-density polyethylene; the melt index of the medium-density polyethylene is preferably 2.5-3.5 g / 10 min, and the density is preferably 0.925-0.940 g / cm3 In specific embodiments of the present application, the medium density polyethylene preferably has a brand of 151BW, a melt index of 3g / 10min, and a density of 0.933g / cm 3 The medium density polyethylene used in the present application has the characteristics of high temperature resistance, good transparency, high compound firmness, and easy processing.

[0048] The preparation raw material of the outer layer of the degradable polyethylene printing film includes 30-70 parts of high density polyethylene, preferably 40-60 parts, based on the weight parts of the medium density polyethylene used in the outer layer of the degradable polyethylene printing film. The high density polyethylene preferably has a melt index of 0.3-1.5g / 10min and a density of 0.955-0.970g / cm 3 In specific embodiments of the present application, the high density polyethylene preferably has a brand of 8300, a melt index of 0.7g / 10min, and a density of 0.963g / cm 3 The high density polyethylene used in the present application has the characteristics of high temperature resistance, high strength, few crystal points, and good transparency.

[0049] The preparation raw material of the outer layer of the degradable polyethylene printing film includes 15-40 parts of medium density metallocene polyethylene, preferably 20-30 parts, based on the weight parts of the medium density polyethylene used in the outer layer of the degradable polyethylene printing film. The medium density metallocene polyethylene preferably has a melt index of 0.2-1.0g / 10min and a density of 0.925-0.940g / cm 3 In specific embodiments of the present application, the medium density metallocene polyethylene preferably has a brand of 3505MA, a melt index of 0.5g / 10min, and a density of 0.935g / cm 3 The medium density metallocene polyethylene used in the present application has the characteristics of high temperature resistance, good transparency, good toughness, and easy processing.

[0050] The preparation raw material of the outer layer of the degradable polyethylene printing film includes 1.5-2.5 parts of a degradation master batch, preferably 2 parts, based on the weight parts of the medium density polyethylene used in the outer layer of the degradable polyethylene printing film. The degradation master batch preferably has a melt index of 46-55g / 10min, more preferably 50-52g / 10min, and a density of 0.920-0.940g / cm 3 more preferably 0.925-0.935g / cm 3 In specific embodiments of the present application, the degradation master batch preferably has a brand of TRF-57, a melt index of 51g / 10min, and a density of 0.93g / cm 3, the manufacturer is Polymateria, UK; the degradation master batch used in the application can convert polyethylene into biologically available wax, without the need for specific environmental degradation, and without leaving microplastics or toxic substances after degradation, harmless to nature; and after adding the degradation master batch, the physical properties of the film do not change, and compared with other degradable films, the application range is wider and the cost is lower; adding the degradation master batch does not need to change the original process equipment, and can be recycled and granulated with general plastics without affecting the physical properties. Specifically, under the catalytic action of the degradation master batch, polyethylene can undergo the following three chemical reactions: 1. When subjected to energy such as light and heat, the carbon structure chain of polyethylene molecular bond is broken to generate high-activity free radicals; 2. Free radical growth, high-activity free radicals rapidly react to generate intermediate products such as peroxide free radicals or hydroperoxide free radicals under aerobic conditions; 3. Chain termination, the compounds containing unstable peroxide free radicals or hydroperoxide free radicals undergo molecular bond rupture and a series of chemical reactions to generate small molecular compounds with carbon, hydrogen and oxygen structures, which eventually become carbon dioxide, water and wax, which are non-toxic and harmless to nature, and the wax is biologically converted by naturally occurring bacteria and fungi in the soil under open environmental temperature conditions; the final degradable polyethylene printing film meets the degradation requirements of ASTM6954, GB / T20197 and BSI PAS 9017.

[0051] Based on the weight fraction of the medium-density polyethylene used in the outer layer of the degradable polyethylene printing film, the preparation raw materials of the outer layer of the degradable polyethylene printing film include 0.5-1 parts, preferably 0.8-1 parts, of a processing aid; the melt index of the processing aid is preferably 1.5-2.8 g / min, more preferably 1.8-2.5 g / min, and the density is preferably 0.910-0.920 g / cm 3 , more preferably 0.912-0.915 g / cm 3 ; the processing aid is preferably a functional master batch prepared from a fluoropolymer and a polyolefin resin; in specific embodiments of the application, the processing aid is preferably PA0895LD, which has a melt index of 2.1 g / min and a density of 0.915 g / cm 3 , and the manufacturer is Suzhou Constap Engineering Plastics Co., Ltd.; the processing aid used in the application can effectively reduce die buildup, reduce crystal points and reduce extrusion pressure, thereby improving production efficiency.

[0052] The preparation raw materials of the middle layer of the degradable polyethylene printing film include 10-40 parts, preferably 20-30 parts, of a first medium-density metallocene polyethylene, in terms of mass fraction; the melt index of the first medium-density metallocene polyethylene is preferably 0.2-1.0 g / 10 min, and the density is preferably 0.935-0.945 g / cm 3; in specific embodiments of the present application, the first medium density metallocene polyethylene has a brand of 4009, preferably a melt index of 0.5g / 10min, and a density of 0.94g / cm 3 ; the first medium density metallocene polyethylene used in the present application has the characteristics of high temperature resistance, good transparency, and good toughness.

[0053] The preparation raw material of the middle layer of the degradable polyethylene printing film includes 10-30 parts, preferably 15-25 parts of the second medium density metallocene polyethylene, based on the weight parts of the first medium density metallocene polyethylene used in the middle layer of the degradable polyethylene printing film; the second medium density metallocene polyethylene has a melt index of 2.0-3.0g / 10min, and a density of 0.930-0.940g / cm 3 ; in specific embodiments of the present application, the second medium density metallocene polyethylene has a brand of 2036P, preferably a melt index of 2.5g / 10min, and a density of 0.935g / cm 3 ; the second medium density metallocene polyethylene used in the present application has the characteristics of high transparency, good toughness, and easy processing.

[0054] The preparation raw material of the middle layer of the degradable polyethylene printing film includes 30-85 parts, preferably 40-70 parts of the high-strength low-density metallocene polyethylene, based on the weight parts of the first medium density metallocene polyethylene used in the middle layer of the degradable polyethylene printing film; the high-strength low-density metallocene polyethylene has a melt index of 0.2-1.0g / 10min, and a density of 0.910-0.920g / cm 3 ; in specific embodiments of the present application, the high-strength low-density metallocene polyethylene has a brand of XP6056ML, preferably a melt index of 0.5g / 10min, and a density of 0.916g / cm 3 ; the high-strength low-density metallocene polyethylene used in the present application has the characteristics of good transparency, good toughness, and high puncture strength.

[0055] The preparation raw material of the middle layer of the degradable polyethylene printing film includes 1.5-2.5 parts, preferably 2 parts of the degradation master batch, based on the weight parts of the first medium density metallocene polyethylene used in the middle layer of the degradable polyethylene printing film; the melt index, density, and specific brand of the degradation master batch used in the middle layer of the degradable polyethylene printing film are preferably consistent with those of the degradation master batch used in the outer layer, which will not be described herein.

[0056] Based on the weight percentage of the first medium-density metallocene polyethylene used in the middle layer of the biodegradable polyethylene printing film, the raw materials for preparing the middle layer of the biodegradable polyethylene printing film include 0.5 to 1 part of processing aids, preferably 0.5 to 0.6 parts; the melt index, density and specific grade of the processing aids used in the middle layer of the biodegradable polyethylene printing film are preferably the same as those used in the outer layer, and will not be repeated here.

[0057] In this invention, the raw materials for preparing the inner layer of the biodegradable polyethylene printed film are the same as those for the outer layer, and will not be described again here.

[0058] The composition of high-barrier polyethylene heat-sealing film is described below.

[0059] The raw materials for preparing the outer layer of the high-barrier polyethylene heat-sealable film, by weight, include 10-30 parts, preferably 15-25 parts, of low-density polyethylene; the melt index of the low-density polyethylene is preferably 1.5-2.5 g / 10 min, and the density is preferably 0.920-0.930 g / cm³. 3 In a specific embodiment of the present invention, the low-density polyethylene is grade 2420H, with a melt index preferably of 2 g / 10 min and a density preferably of 0.924 g / cm³. 3 The manufacturer is BASF Yangtze. The low-density polyethylene used in this invention has the characteristics of good transparency, strong composite strength and easy processing.

[0060] Based on the weight percentage of low-density polyethylene used in the outer layer of the high-barrier polyethylene heat-sealing film, the raw materials for preparing the outer layer of the high-barrier polyethylene heat-sealing film include 15-40 parts, preferably 20-30 parts, of low-density metallocene polyethylene; the melt index of the low-density metallocene polyethylene is preferably 1.5-2.5 g / 10 min, and the density is preferably 0.908-0.920 g / cm³. 3 In a specific embodiment of the present invention, the low-density metallocene polyethylene is grade 1520, with a preferred melt index of 1.9 g / 10 min and a preferred density of 0.913 g / cm³. 3 The manufacturer is Mitsui Chemicals Co., Ltd. The low-density metallocene polyethylene used in this invention has properties such as good coating adhesion, high transparency, high toughness, and few crystal points.

[0061] Based on the weight percentage of low-density polyethylene used in the outer layer of the high-barrier polyethylene heat-sealable film, the raw materials for preparing the outer layer of the high-barrier polyethylene heat-sealable film include 20-75 parts of linear low-density polyethylene, preferably 30-60 parts; the melt index of the linear low-density polyethylene is preferably 1.5-2.5 g / 10 min, and the density is preferably 0.910-0.925 g / cm³. 3; in specific embodiments of the present application, the linear low density polyethylene preferably has a brand of 7042, preferably a melt index of 2g / 10min, and a density of 0.918g / cm 3 ; the linear low density polyethylene used in the present application has good transparency, good toughness, and easy processing.

[0062] The preparation raw material of the outer layer of the high barrier polyethylene heat-seal film includes 1.5-2.5 parts of the degradation master batch, preferably 2 parts, based on the weight parts of the low density polyethylene used in the outer layer of the high barrier polyethylene heat-seal film; the melt index, density, and specific brand of the degradation master batch used in the outer layer of the high barrier polyethylene heat-seal film are preferably the same as those of the degradation master batch used in the outer layer of the degradable polyethylene printing film, which will not be described herein again.

[0063] The preparation raw material of the outer layer of the high barrier polyethylene heat-seal film includes 0.5-1 parts of the processing aid, preferably 0.5-0.6 parts, based on the weight parts of the low density polyethylene used in the outer layer of the high barrier polyethylene heat-seal film; the melt index, density, and specific brand of the processing aid used in the outer layer of the high barrier polyethylene heat-seal film are preferably the same as those of the processing aid used in the outer layer of the degradable polyethylene printing film, which will not be described herein again.

[0064] The preparation raw material of the middle layer of the high barrier polyethylene heat-seal film includes 10-30 parts of the low density polyethylene, preferably 15-25 parts, based on the mass parts; the melt index of the low density polyethylene is preferably 1.5-2.5g / 10min, and the density is preferably 0.920-0.930g / cm 3 ; in specific embodiments of the present application, the low density polyethylene preferably has a brand of 2420H, preferably a melt index of 2g / 10min, and a density of 0.924g / cm 3 ; the low density polyethylene used in the present application has good transparency, good composite fastness, and easy processing.

[0065] The preparation raw material of the middle layer of the high barrier polyethylene heat-seal film includes 10-50 parts of the linear low density polyethylene, preferably 20-40 parts, based on the weight parts of the low density polyethylene used in the middle layer of the high barrier polyethylene heat-seal film; the melt index of the linear low density polyethylene is preferably 1.5-2.5g / 10min, and the density is preferably 0.910-0.925g / cm 3 ; in specific embodiments of the present application, the linear low density polyethylene preferably has a brand of 201XV, preferably a melt index of 2g / 10min, and a density of 0.918g / cm 3 ; the linear low density polyethylene used in the present application has good transparency, good toughness, and easy processing.

[0066] The preparation raw material of the middle layer of the high-barrier polyethylene heat-seal film includes 30-80 parts of low-density metallocene polyethylene, preferably 40-70 parts, based on the weight parts of the low-density polyethylene used in the middle layer of the high-barrier polyethylene heat-seal film. The melt index of the low-density metallocene polyethylene is preferably 0.5-2.0 g / 10 min, and the density is preferably 0.910-0.925 g / cm 3 In specific embodiments of the present application, the grade of the low-density metallocene polyethylene is preferably 1018BN, the melt index is preferably 1 g / 10 min, and the density is preferably 0.918 g / cm 3 , and the manufacturer is LG Chemical. The low-density metallocene polyethylene used in the present application has the properties of high transparency, high toughness, and few crystal points.

[0067] The preparation raw material of the middle layer of the high-barrier polyethylene heat-seal film includes 1.5-2.5 parts of degradation master batch, preferably 2 parts, based on the weight parts of the low-density polyethylene used in the middle layer of the high-barrier polyethylene heat-seal film. The melt index, density, and specific grade of the degradation master batch used in the middle layer of the high-barrier polyethylene heat-seal film are preferably consistent with those of the degradation master batch used in the outer layer of the degradable polyethylene printing film, which will not be repeated here.

[0068] The preparation raw material of the middle layer of the high-barrier polyethylene heat-seal film includes 0.5-1 parts of processing aid, preferably 0.5-0.6 parts, based on the weight parts of the low-density polyethylene used in the middle layer of the high-barrier polyethylene heat-seal film. The melt index, density, and specific grade of the processing aid used in the middle layer of the high-barrier polyethylene heat-seal film are preferably consistent with those of the processing aid used in the outer layer of the degradable polyethylene printing film, which will not be repeated here.

[0069] The preparation raw material of the inner layer of the high-barrier polyethylene heat-seal film includes 10-25 parts of low-density polyethylene, preferably 15-20 parts, based on the mass parts. The melt index of the low-density polyethylene is preferably 1.5-2.5 g / 10 min, and the density is preferably 0.920-0.930 g / cm 3 In specific embodiments of the present application, the grade of the low-density polyethylene is preferably 2426H, the melt index is preferably 2 g / 10 min, and the density is preferably 0.924 g / cm 3 , and the manufacturer is Sinopec Maoming Branch. This low-density polyethylene has the characteristics of good transparency, good heat-sealing property, good opening property, and easy processing.

[0070] The preparation raw material of the inner layer of the high-barrier polyethylene heat-seal film includes 30-80 parts, preferably 40-70 parts of low-density metallocene polyethylene, with the melt index of the low-density metallocene polyethylene being preferably 0.3-1.5 g / 10 min and the density being preferably 0.900-0.915 g / cm 3 In specific embodiments of the present application, the low-density metallocene polyethylene preferably has the brand AT6202, with the melt index being preferably 0.85 g / 10 min and the density being preferably 0.908 g / cm 3 , produced by Dow Chemical, and has excellent anti-pollution heat-seal property, low seal initiation temperature, high toughness, and few crystal points.

[0071] The preparation raw material of the inner layer of the high-barrier polyethylene heat-seal film includes 30-80 parts, preferably 40-70 parts of low-density metallocene polyethylene, with the melt index of the low-density metallocene polyethylene being preferably 0.3-1.5 g / 10 min and the density being preferably 0.900-0.915 g / cm 3 In specific embodiments of the present application, the low-density metallocene polyethylene preferably has the brand AT6202, with the melt index being preferably 0.85 g / 10 min and the density being preferably 0.908 g / cm 3 , produced by Dow Chemical, and has excellent anti-pollution heat-seal property, low seal initiation temperature, high toughness, and few crystal points.

[0072] The preparation raw material of the inner layer of the high-barrier polyethylene heat-seal film includes 30-80 parts, preferably 40-70 parts of low-density metallocene polyethylene, with the melt index of the low-density metallocene polyethylene being preferably 0.3-1.5 g / 10 min and the density being preferably 0.900-0.915 g / cm

[0073] The preparation raw material of the inner layer of the high-barrier polyethylene heat-seal film includes 30-80 parts, preferably 40-70 parts of low-density metallocene polyethylene, with the melt index of the low-density metallocene polyethylene being preferably 0.3-1.5 g / 10 min and the density being preferably 0.900-0.915 g / cm

[0074] In the present application, the mass fraction of the outer layer in the degradable polyethylene printing film is preferably 20-30%, the mass fraction of the middle layer is preferably 40-60%, and the mass fraction of the inner layer is preferably 20-30%; the mass fraction of the outer layer in the high-barrier degradable polyethylene heat-seal film is 25-30%, the mass fraction of the middle layer is 40-50%, and the mass fraction of the inner layer is 25-30%.

[0075] In the present application, the thickness of the degradable polyethylene printing film is preferably 30-80 μm, more preferably 40 μm, the thickness of the high-barrier degradable polyethylene heat-seal film is preferably 40-100 μm, more preferably 60 μm, and the thickness of the high-barrier degradable polyethylene composite film is preferably 70-180 μm, more preferably 100 μm.

[0076] In the present application, the longitudinal tensile strength of the degradable polyethylene printing film is preferably 44-46 MPa, the transverse tensile strength is preferably 42-43 MPa, the longitudinal elongation at break is preferably 590-620%, the transverse elongation at break is preferably 710-720%, the haze is preferably ≤10.5%, more preferably ≤10.1%, and the wetting tension is preferably 40-45 mN / 15 mm.

[0077] In the present application, the longitudinal tensile strength of the high-barrier degradable polyethylene heat-seal film is preferably 32-34 MPa, the transverse tensile strength is preferably 29-31 MPa, the longitudinal elongation at break is preferably 540-560%, the transverse elongation at break is preferably 730-740%, the haze is preferably ≤10.5%, more preferably ≤10.3%, the wetting tension is preferably 40-45 mN / 15 mm, the water vapor transmission rate is preferably ≤4.5%, more preferably ≤4.1%, and the oxygen transmission rate is preferably ≤3.5%.

[0078] In the present application, the high-barrier degradable polyethylene composite film is obtained by compounding the degradable polyethylene printing film and the high-barrier polyethylene heat-seal film, specifically, the outer layer (i.e. the corona layer) of the degradable polyethylene printing film and the outer layer (i.e. the corona layer) of the high-barrier polyethylene heat-seal film are adhered; the outer layer of the degradable polyethylene printing film is the printing layer, specifically, the compounding is performed after printing.

[0079] In the present application, the high-barrier degradable polyethylene composite film preferably has a longitudinal tensile strength of 38-39 MPa, a transverse tensile strength of 35-37 MPa, a longitudinal elongation at break of 450-460%, a transverse elongation at break of 710-720%, a haze of ≤12.5%, more preferably ≤12.3%, a wetting tension of 40-45 mN / 15 mm, a water vapor transmission rate of ≤4.0%, more preferably ≤3.7%, and an oxygen transmission rate of ≤3.5%; and the high-barrier degradable polyethylene composite film can be effectively degraded under natural environment, photodegradation, thermal oxidative degradation, and composting conditions.

[0080] The present application also provides a preparation method of the high-barrier degradable polyethylene composite film described in the above-mentioned scheme, comprising the following steps:

[0081] The preparation raw materials of the outer layer, the middle layer, and the inner layer of the degradable polyethylene printing film are subjected to three-layer co-extrusion blown film to obtain the degradable polyethylene printing film.

[0082] The preparation raw materials of the outer layer, the middle layer, and the inner layer of the high-barrier degradable polyethylene heat-seal film are subjected to three-layer co-extrusion blown film to obtain the high-barrier degradable polyethylene heat-seal film.

[0083] The degradable polyethylene printing film and the high-barrier degradable polyethylene heat-seal film are compounded by using an adhesive, and the high-barrier degradable polyethylene composite film is obtained after curing.

[0084] In the present application, the preparation raw materials of the outer layer, the middle layer, and the inner layer of the degradable polyethylene printing film are subjected to three-layer co-extrusion blown film (denoted as first co-extrusion blown film) to obtain the degradable polyethylene printing film. In the present application, the process of the first co-extrusion blown film specifically comprises: the preparation raw materials of the outer layer, the middle layer, and the inner layer are respectively fed into the outer layer extruder, the middle layer extruder, and the inner layer extruder for melt plasticization, the obtained glue solution is transported to a die head, extrusion blown film is performed to obtain a film bubble, and the film bubble is cooled to sequentially perform bubble stabilization, upper traction, corona treatment, edge cutting, lower traction, and winding to obtain the degradable polyethylene printing film.

[0085] In the present application, the outer layer extruder, the middle layer extruder, and the inner layer extruder used in the first co-extrusion blown film are each preferably provided with 5 heating zones, which are sequentially denoted as Zone 1-Zone 5 according to the passing order of raw materials; and the die head is provided with 4 heating zones, which are sequentially denoted as Zone 1-Zone 4 according to the passing order of raw materials.

[0086] In the present application, the extrusion temperatures of each zone of the outer layer extruder, the middle layer extruder, the inner layer extruder, and the die head used in the first co-extrusion blown film are shown in Table 1:

[0087] Table 1 Extrusion temperatures of each zone of the outer layer extruder, the middle layer extruder, the inner layer extruder, and the die head used in the first co-extrusion blown film

[0088]

[0089]

[0090] In the present application, the extrusion pressure of the first extrusion blown film outer layer extruder is preferably 225-315 bar, the extrusion pressure of the middle layer extruder is preferably 215-355 bar, and the extrusion pressure of the inner layer extruder is preferably 205-285 bar.

[0091] The present application prepares the raw materials of the outer layer, the middle layer and the inner layer of the high-barrier degradable polyethylene heat-seal film into a three-layer co-extrusion blown film (referred to as a second co-extrusion blown film), to obtain the high-barrier degradable polyethylene heat-seal film. In the present application, the specific operation process of the second co-extrusion blown film is consistent with that of the first co-extrusion blown film, and will not be repeated here; the outer layer extruder, the middle layer extruder and the inner layer extruder used in the second co-extrusion blown film are all preferably provided with 5 heating zones, which are sequentially referred to as Zone 1-Zone 5 in the order of raw material passing; the die is provided with 4 heating zones, which are sequentially referred to as Zone 1-Zone 4 in the order of raw material passing.

[0092] In the present application, the extrusion temperature of each zone of the outer layer extruder, the middle layer extruder, the inner layer extruder and the die used in the second co-extrusion blown film is shown in Table 2:

[0093] Table 2 Extrusion temperature of each zone of the outer layer, the middle layer, the inner layer extruder and the die of the second co-extrusion blown film

[0094] Temperature Zone 1 Zone 2 Zone 3 Zone 4 Zone 5 Outer layer 162±5℃ 168±5℃ 170±5℃ 165±5℃ 160±5℃ Middle layer 165±5℃ 170±5℃ 172±5℃ 168±5℃ 165±5℃ Inner layer 170±5℃ 175±5℃ 178±5℃ 172±5℃ 168±5℃ Die 180±5℃ 186±5℃ 182±5℃ 180±5℃

[0095] The extrusion pressure of the second extrusion blown film outer layer extruder is preferably 235-318 bar, the extrusion pressure of the middle layer extruder is preferably 205-335 bar, and the extrusion pressure of the inner layer extruder is preferably 225-310 bar.

[0096] After obtaining the degradable polyethylene printing film and the high-barrier degradable polyethylene heat-seal film, the degradable polyethylene printing film and the high-barrier degradable polyethylene heat-seal film are compounded by using an adhesive, and the high-barrier degradable polyethylene composite film is obtained after curing. In the present application, before compounding, printing is also performed on the surface of the outer layer (i.e. the corona layer) of the degradable polyethylene printing film, and the printing method is preferably gravure printing; the adhesive is preferably a solvent-free adhesive, and the solvent-free adhesive is preferably a two-component solvent-free polyurethane adhesive of Wanhua Chemical (Beijing) Co., Ltd., model 6039A / 739B; in the present application, PVA solution is preferably coated on the surface of the outer layer (i.e. the corona layer) of the high-barrier degradable polyethylene heat-seal film first, and then the printing surface of the degradable polyethylene printing film and the outer layer of the high-barrier degradable polyethylene heat-seal film are compounded by using a solvent-free process; the coating thickness of the PVA solution is preferably 0.5-1 μm, the concentration of the PVA solution is preferably 12-15 wt%, and the solvent of the PVA solution is preferably water; in the present application, a layer of PVA solution is coated on the surface of the high-barrier degradable polyethylene heat-seal film first, which can improve the oxygen barrier property of the film and the shelf life of the product; the compounding conditions are preferably as follows: mixing temperature: both components A and B are set to 38℃; coating temperature: the temperature of each steel roller of the coating glue system is set to 45℃; the mass ratio of the glue 6039A and 739B is 100 / 60; the glue amount is 1.5-2.2 g / m 2 The present application does not have special requirements for the operation process of compounding, and a solvent-free process known to those skilled in the art can be used.

[0097] In the present application, the curing temperature is preferably 35-45℃, and more preferably 40℃, and the curing time is preferably 24-48 h, and more preferably 48 h.

[0098] The present application also provides a high-barrier degradable polyethylene composite bag prepared from the high-barrier degradable polyethylene composite film, and the high-barrier degradable polyethylene composite film is the high-barrier degradable polyethylene composite film described in the above scheme or prepared by the preparation method described in the above scheme; the present application does not have special requirements for the method of bag making, and a method known to those skilled in the art can be used. In the specific embodiments of the present application, the heat-seal layer of the high-barrier degradable polyethylene composite film is preferably contacted and heat-sealed according to the required bag type, and the heat-sealing conditions are preferably as follows: the edge sealing temperature is 150-160℃, the bottom sealing temperature is 160-170℃, and the heat-sealing pressure is 4-6 kg.

[0099] The technical solutions in the present application will be described clearly and completely in combination with the embodiments in the present application, but it should not be understood as a limitation on the protection scope of the present application.

[0100] The sources and performance parameters of the raw materials used in the examples are shown in Tables 3-4.

[0101] Table 3 Sources and performance parameters of the raw materials used in the preparation of the degradable polyethylene printing film in the examples

[0102]

[0103]

[0104] Table 4 Sources and performance parameters of the raw materials used in the preparation of the high-barrier degradable polyethylene heat-seal film in the examples

[0105]

[0106] Example 1

[0107] The degradable polyethylene printing film is a three-layer structure, and the weight percentages of the outer layer, middle layer, and inner layer materials are: 25% for the outer layer, 50% for the middle layer, and 25% for the inner layer.

[0108] The preparation method of the degradable polyethylene printing film is as follows: the outer layer, middle layer, and inner layer raw materials are mixed in proportion by an automatic batching system and then sent to the outer layer, middle layer, and inner layer extruders. The raw materials of the outer layer, middle layer, and inner layer are melted and plasticized and then sent to the die. The film is extruded, air-cooled, and then stabilized by a stabilizing ring and a herringbone arrangement. The cylinder is flattened by an upper traction rotation, enters the guide roller, and is subjected to corona treatment in a corona treatment device. The edges are cut, and the film enters the front and rear winding devices through the lower traction clamping roller for front and rear winding, thereby obtaining a 40-μm degradable polyethylene printing film. The raw material proportions of the outer layer, middle layer, and inner layer of the degradable polyethylene printing film are shown in Table 5, and the temperatures and pressures of the outer layer, middle layer, and inner layer extruders and the die are shown in Table 6.

[0109] The high-barrier degradable polyethylene heat-seal film is a three-layer structure, and the weight percentages of the outer layer, middle layer, and inner layer materials are: 30% for the outer layer, 40% for the middle layer, and 30% for the inner layer. The preparation method of the high-barrier degradable polyethylene heat-seal film is consistent with that of the degradable polyethylene printing film. The raw material proportions of the outer layer, middle layer, and inner layer are shown in Table 7, and the temperatures and pressures of the outer layer, middle layer, and inner layer extruders and the die are shown in Table 8. The thickness of the high-barrier degradable polyethylene heat-seal film is 60 μm.

[0110] The prepared degradable polyethylene printing film is printed according to a conventional gravure process; the high-barrier degradable polyethylene heat-seal film is coated with a PVA solution on the surface, and the coating thickness is 0.5 μm; the degradable polyethylene printing film after printing and the high-barrier degradable polyethylene heat-seal film are compounded by means of a solvent-free adhesive, the solvent-free adhesive used is a two-component solvent-free polyurethane adhesive of Wanhua Chemical (Beijing) Co., Ltd., 6039A / 739B, and the compounding conditions include: mixing adhesive temperature: the A and B components are both set to 38 ℃; coating temperature: the steel roller temperature of the coating adhesive system is set to 45 ℃; adhesive ratio A / B = 100 / 60; adhesive amount is 2.1 g / m 2 .

[0111] After the compounded film is placed in a curing room at 40 ℃±5 ℃ for curing for 48 h, it is taken out and placed at room temperature for 12 h to obtain a high-barrier degradable polyethylene compounded film, and then a bag is prepared according to a conventional process for a required bag type to obtain a high-barrier degradable polyethylene compounded bag.

[0112] Table 5 Raw material usage amount (by mass) of the three layers of the degradable polyethylene printing film

[0113]

[0114] Table 6 Extruder temperature and pressure during preparation of the degradable polyethylene printing film

[0115] Temperature Zone 1 Zone 2 Zone 3 Zone 4 Zone 5 Pressure (bar) Outer layer 172℃ 178℃ 175℃ 170℃ 165℃ 225～315 Middle layer 175℃ 182℃ 178℃ 175℃ 172℃ 215～355 Inner layer 172℃ 178℃ 175℃ 170℃ 165℃ 205～285 Die 185℃ 190℃ 185℃ 180℃

[0116] Table 7 Raw material usage amount (by mass) of the three layers of the high-barrier degradable polyethylene heat-seal film

[0117]

[0118] Table 8 Extruder temperature and pressure during preparation of the high-barrier degradable polyethylene heat-seal film

[0119] Temperature Zone 1 Zone 2 Zone 3 Zone 4 Zone 5 Pressure (bar) Outer layer 162℃ 168℃ 170℃ 165℃ 160℃ 225～318 Middle layer 165℃ 170℃ 172℃ 168℃ 165℃ 205～335 Inner layer 170℃ 175℃ 178℃ 172℃ 168℃ 225～310 Die 180℃ 186℃ 182℃ 180℃

[0120] Example 2

[0121] The weight percentage of the three layers of the degradable polyethylene printing film is: 30% for the outer layer, 40% for the middle layer, and 30% for the inner layer, and the thickness of the degradable polyethylene printing film is 40 μm. The weight percentage of the three layers of the high-barrier degradable polyethylene heat-seal film is: 25% for the outer layer, 45% for the middle layer, and 30% for the inner layer, and the thickness of the high-barrier degradable polyethylene heat-seal film is 60 μm. The raw material usage amount of each layer is shown in Tables 5 and 7.

[0122] The preparation method is the same as that in Example 1, and a high-barrier degradable polyethylene compounded film and bag are obtained.

[0123] Example 3

[0124] The weight percentage of the three layers of the degradable polyethylene printing film was: 20% for the outer layer, 60% for the middle layer, and 20% for the inner layer, and the thickness of the degradable polyethylene printing film was 40 μm. The weight percentage of the three layers of the high-barrier degradable polyethylene heat-seal film was: 25% for the outer layer, 50% for the middle layer, and 25% for the inner layer, and the thickness of the high-barrier degradable polyethylene heat-seal film was 60 μm. The raw material usage of each layer is shown in Tables 5 and 7.

[0125] The preparation method was the same as in Example 1, and a high-barrier degradable polyethylene composite film and a bag were obtained.

[0126] Comparative Example 1

[0127] The composite film of Comparative Example 1 was a composite structure of a PET printing layer and a PE heat-seal layer, wherein the PET layer was the printing layer and had a thickness of 12 μm, and was a commercially available product; and the PE heat-seal layer was a high-barrier EVOH co-extrusion heat-seal film and had a thickness of 60 μm, and was a commercially available product.

[0128] The purchased PET printing film was printed according to the requirements of the customer using a conventional gravure process;

[0129] The printed PET film and the purchased high-barrier EVOH co-extrusion heat-seal film were compounded by a solvent-free adhesive, and the adhesive used was a two-component solvent-free polyurethane adhesive from Wanhua Chemical (Beijing) Co., Ltd., with a model number of 6039A / 739B. The compounding conditions were as follows: mixing adhesive temperature: both components A and B were set to 40°C; coating temperature: the temperature of each steel roller of the coating adhesive system was set to 45°C; adhesive ratio A / B = 100 / 60 (mass ratio); and adhesive coating amount was 2.1 g / m 2 ;

[0130] The composite film was placed in a curing room at 48°C±5°C for curing for 48 hours, and after cooling for 12 hours, a bag was prepared according to the conventional process for the required bag type, and a composite bag was obtained.

[0131] Comparative Example 2

[0132] The weight percentage of the three layers of the polyethylene printing film was: 20% for the outer layer, 60% for the middle layer, and 20% for the inner layer, and the thickness of the polyethylene printing film was 40 μm. The weight percentage of the three layers of the high-barrier polyethylene heat-seal film was: 25% for the outer layer, 50% for the middle layer, and 25% for the inner layer, and the thickness of the high-barrier polyethylene heat-seal film was 60 μm. The raw material usage of each layer is shown in Tables 5 and 7.

[0133] The preparation method was the same as in Example 1, and a polyethylene composite film and a bag were obtained.

[0134] Performance test:

[0135] The mechanical properties, wetting tension, haze, ink layer adhesion and degradation performance of the degradable polyethylene printing film prepared in Examples 1-3 and Comparative Example 2, and the PET film in Comparative Example 1 were tested, and the results are shown in Table 9.

[0136] Table 9 Test results of degradable polyethylene printing film performance

[0137]

[0138] According to the data in Table 9, it can be seen that the degradable polyethylene printing film prepared by the present application has good mechanical properties, low haze, high ink layer adhesion, and can be effectively degraded under the conditions of light, heat and oxygen and composting, while the degradation performance of the PET film in Comparative Example 1 is unqualified, and the outer layer, middle layer and inner layer of the polyethylene printing film in Comparative Example 2 do not add degradation masterbatch, and the degradation performance under the conditions of light, heat and oxygen and composting is unqualified.

[0139] The mechanical properties, wetting tension, haze, barrier properties, heat seal strength and degradation performance of the high barrier degradable polyethylene heat seal film prepared in Examples 1-3 and Comparative Example 2, and the high barrier EVOH co-extrusion heat seal film in Comparative Example 1 were tested, and the results are shown in Table 10.

[0140] Table 10 Test results of high barrier degradable polyethylene heat seal film performance

[0141]

[0142]

[0143] According to the data in Table 10, it can be seen that the high barrier degradable polyethylene heat seal film prepared by the present application has good mechanical properties, low haze, good water vapor and oxygen barrier properties, good heat seal strength, and can be effectively degraded under the conditions of light, heat and oxygen and composting, while the degradation performance of the PET film in Comparative Example 1 is unqualified, and the outer layer, middle layer and inner layer of the high barrier polyethylene heat seal film in Comparative Example 2 do not add degradation masterbatch, and the degradation performance under the conditions of light, heat and oxygen and composting is unqualified.

[0144] The mechanical properties, wetting tension, haze, barrier properties, ink layer adhesion, heat seal strength and degradation performance of the composite film prepared in Examples 1-3 and Comparative Examples 1-2 were tested, and the results are shown in Table 11.

[0145] Table 11 Test results of composite performance

[0146]

[0147]

[0148] According to the detection data in Table 11, it can be seen that the high-barrier degradable polyethylene composite film prepared by the application has good mechanical properties, low haze, good barrier property, high ink layer structure firmness, and excellent degradation performance; the composite films in Comparative Examples 1-2 have unqualified degradation performance.

[0149] The above only describes the preferred embodiments of the present application, and it should be noted that those skilled in the art can make several improvements and refinements without departing from the principles of the present application, and these improvements and refinements should also be considered within the protection scope of the present application.

Claims

1. A high-barrier degradable polyethylene composite film, characterized by, The degradable polyethylene printing film is compounded with a high-barrier polyethylene heat-seal film; The degradable polyethylene printing film comprises an outer layer, a middle layer and an inner layer; The preparation raw materials of the outer layer and the inner layer of the degradable polyethylene printing film independently comprise, in mass fraction, 10-30 parts of medium-density polyethylene, 30-70 parts of high-density polyethylene, 15-40 parts of medium-density metallocene polyethylene, 1.5-2.5 parts of a degradation master batch and 0.5-1 part of a processing aid; The preparation raw materials of the middle layer of the degradable polyethylene printing film comprise, in mass fraction, 10-40 parts of first medium-density metallocene polyethylene, 10-30 parts of second medium-density metallocene polyethylene, 30-85 parts of high-strength low-density metallocene polyethylene, 1.5-2.5 parts of a degradation master batch and 0.5-1 part of a processing aid; the high-strength low-density metallocene polyethylene has a brand XP6056ML; The high-barrier polyethylene heat-seal film comprises an outer layer, a middle layer and an inner layer; The preparation raw materials of the outer layer of the high-barrier polyethylene heat-seal film comprise, in mass fraction, 10-30 parts of low-density polyethylene, 15-40 parts of low-density metallocene polyethylene, 20-75 parts of linear low-density polyethylene, 1.5-2.5 parts of a degradation master batch and 0.5-1 part of a processing aid; The preparation raw materials of the middle layer of the high-barrier polyethylene heat-seal film comprise, in mass fraction, 10-30 parts of low-density polyethylene, 10-50 parts of linear low-density polyethylene, 30-80 parts of low-density metallocene polyethylene, 1.5-2.5 parts of a degradation master batch and 0.5-1 part of a processing aid; The preparation raw materials of the inner layer of the high-barrier polyethylene heat-seal film comprise, in mass fraction, 10-25 parts of low-density polyethylene, 30-80 parts of low-density metallocene polyethylene, 20-60 parts of ultra-low-density metallocene polyethylene, 1.5-2.5 parts of a degradation master batch and 0.5-1 part of a processing aid.

2. The high-barrier degradable polyethylene composite film according to claim 1, characterized in that, The raw materials for preparing the outer layer and the inner layer of the degradable polyethylene printing film include: medium density polyethylene with a melt index of 2.5-3.5 g / 10 min and a density of 0.925-0.940 g / cm 3 ; high density polyethylene with a melt index of 0.3-1.5 g / 10 min and a density of 0.955-0.970 g / cm 3 ; and medium density metallocene polyethylene with a melt index of 0.2-1.0 g / 10 min and a density of 0.925-0.940 g / cm 3 ; The raw material for preparing the middle layer of the degradable polyethylene printing film has: the first middle density metallocene polyethylene has a melt index of 0.2-1.0 g / 10 min and a density of 0.935-0.945 g / cm 3 ; the second middle density metallocene polyethylene has a melt index of 2.0-3.0 g / 10 min and a density of 0.930-0.940 g / cm 3 ; and the high-strength low-density metallocene polyethylene has a melt index of 0.2-1.0 g / 10 min and a density of 0.910-0.920 g / cm 3 .

3. The high-barrier degradable polyethylene composite film according to claim 1, characterized in that, The raw material for preparing the outer layer of the high-barrier polyethylene heat-seal film comprises: low-density polyethylene with a melt index of 1.5-2.5 g / 10 min and a density of 0.920-0.930 g / cm 3 ; low-density metallocene polyethylene with a melt index of 1.5-2.5 g / 10 min and a density of 0.908-0.920 g / cm 3 ; linear low-density polyethylene with a melt index of 1.5-2.5 g / 10 min and a density of 0.910-0.925 g / cm 3 ; The raw material for preparing the middle layer of the high-barrier polyethylene heat-seal film comprises: low-density polyethylene with a melt index of 1.5-2.5 g / 10 min and a density of 0.920-0.930 g / cm 3 ; linear low-density polyethylene with a melt index of 1.5-2.5 g / 10 min and a density of 0.910-0.925 g / cm 3 ; and low-density metallocene polyethylene with a melt index of 0.5-2.0 g / 10 min and a density of 0.910-0.925 g / cm 3 ; The raw material for preparing the inner layer of the high-barrier polyethylene heat-seal film comprises low-density polyethylene with a melt index of 1.5-2.5 g / 10 min and a density of 0.920-0.930 g / cm 3 ; low-density metallocene polyethylene with a melt index of 0.3-1.5 g / 10 min and a density of 0.900-0.915 g / cm 3 ; and ultra-low-density metallocene polyethylene with a melt index of 0.5-1.8 g / 10 min and a density of 0.890-0.915 g / cm 3 .

4. The high-barrier degradable polyethylene composite film according to claim 1, characterized in that, The melt index of the degradation master batch used in the outer, middle and inner layers of the degradable polyethylene printing film and the outer, middle and inner layers of the high barrier polyethylene heat seal film is 46-55 g / 10 min, and the density is 0.920-0.940 g / cm 3 The melt index of the processing aid is 1.5.0-2.8 g / 10 min, and the density is 0.910-0.920 g / cm 3 .

5. The high-barrier degradable polyethylene composite film according to any one of claims 1 to 4, characterized in that, In the preparation raw materials of the outer layer and the inner layer of the degradable polyethylene printing film, the medium-density polyethylene has a brand 151BW, and the high-density polyethylene has a brand 8300; In the preparation raw materials of the middle layer of the degradable polyethylene printing film, the first medium-density metallocene polyethylene has a brand 4009, and the second medium-density metallocene polyethylene has a brand 2036P; In the preparation raw materials of the outer layer of the high-barrier polyethylene heat-seal film, the low-density polyethylene has a brand 2420H, the low-density metallocene polyethylene has a brand 1520, and the linear low-density polyethylene has a brand 7042; In the preparation raw materials of the middle layer of the high-barrier polyethylene heat-seal film, the low-density polyethylene has a brand 2420H, the linear low-density polyethylene has a brand 201XV, and the low-density metallocene polyethylene has a brand 1018BN; In the preparation raw materials of the inner layer of the high-barrier polyethylene heat-seal film, the low-density polyethylene has a brand 2426H, the low-density metallocene polyethylene has a brand AT6202, and the ultra-low-density metallocene polyethylene has a brand SP0510H; The processing aid used in the outer layer, the middle layer and the inner layer of the degradable polyethylene printing film and the outer layer, the middle layer and the inner layer of the high-barrier polyethylene heat-seal film has a brand PA0895LD.

6. The high-barrier degradable polyethylene composite film according to any one of claims 1 to 4, characterized in that, The thickness of the degradable polyethylene printing film is 30-80 μm, and the thickness of the high-barrier polyethylene heat-seal film is 40-100 μm. In the degradable polyethylene printing film, the mass fraction of the outer layer is 20-30%, the mass fraction of the middle layer is 40-60%, and the mass fraction of the inner layer is 20-30%. In the high-barrier polyethylene heat-seal film, the mass fraction of the outer layer is 25-30%, the mass fraction of the middle layer is 40-50%, and the mass fraction of the inner layer is 25-30%.

7. The process for the preparation of the high barrier degradable polyethylene composite film according to any one of claims 1 to 6, characterized in that, The method comprises the following steps: The preparation raw materials of the outer layer, the middle layer and the inner layer of the degradable polyethylene printing film are subjected to three-layer co-extrusion blown film to obtain the degradable polyethylene printing film. The preparation raw materials of the outer layer, the middle layer and the inner layer of the high-barrier polyethylene heat-seal film are subjected to three-layer co-extrusion blown film to obtain the high-barrier polyethylene heat-seal film. The degradable polyethylene printing film and the high-barrier polyethylene heat-seal film are compounded by using an adhesive, and the high-barrier degradable polyethylene composite film is obtained after curing.

8. The preparation method according to claim 7, characterized in that, Before the degradable polyethylene printing film and the high-barrier polyethylene heat-seal film are compounded, the surface of the degradable polyethylene printing film is printed.

9. The preparation method according to claim 7, characterized in that, The curing temperature is 35-45 °C, and the curing time is 24-48 h.

10. A high-barrier degradable polyethylene composite bag, characterized by, The high-barrier degradable polyethylene composite film is prepared from the high-barrier degradable polyethylene composite film, which is the high-barrier degradable polyethylene composite film according to any one of claims 1-6 or the high-barrier degradable polyethylene composite film prepared by the preparation method according to any one of claims 7-9.

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