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CN-121989541-A - PET modified atmosphere food packaging material and preparation method thereof

CN121989541ACN 121989541 ACN121989541 ACN 121989541ACN-121989541-A

Abstract

The invention relates to the technical field of modified atmosphere packaging materials, in particular to a PET modified atmosphere food packaging material and a preparation method thereof, which are used for solving the problems that the traditional material lacks sufficient gas permeability regulating and controlling capability and is difficult to realize modified atmosphere environmental control; the PET modified atmosphere food packaging material is formed by sequentially co-extruding an outer layer, an adhesive layer, a barrier layer, an adhesive layer and an inner layer, has good barrier property through the barrier layer, can accurately maintain atmosphere in a package for a long time, effectively prolongs the fresh-keeping period of food, is prepared by modifying the outer layer of PET, has high stiffness, stretching resistance, puncture resistance, good flexibility and impact resistance, is not easy to deform and damage in transportation and stacking, and has high strength, good toughness and puncture resistance of a formed film by taking metallocene polyethylene as the inner layer, and can effectively protect contents.

Inventors

  • LIANG WEIHAO
  • WEN CAN

Assignees

  • 佛山市高明区金榜塑料包装有限公司

Dates

Publication Date
20260508
Application Date
20260205

Claims (9)

  1. The PET modified atmosphere food packaging material is characterized by being formed by sequentially co-extruding an outer layer, a first bonding layer, a barrier layer, a second bonding layer and an inner layer, wherein the outer layer is made of modified PET, the barrier layer is made of high-barrier resin, the first/second bonding layers are made of maleic anhydride grafted polyolefin elastomer, and the inner layer is made of metallocene polyethylene; wherein the modified PET is prepared by the following steps: Step a1, mixing and stirring zinc oxide powder, a catalyst and ethylene glycol, transferring to a melt polymerization kettle, adding terephthalic acid, introducing nitrogen for protection, heating for esterification, performing vacuum polycondensation, cooling through a water tank after the reaction is completed, and granulating in a granulator to obtain master batches; step a2, adding master batch and epoxy chain extender into a mixer, setting a temperature partition of 'low-temperature mixing-medium-temperature reaction', namely, melting the materials in a first region, carrying out mixing reaction in a second region, plasticizing in a third region, granulating, drying, adding the chain extender and an antioxidant, mechanically stirring, transferring into a double-screw extruder, extruding, cooling and shaping through a cooling water tank, adding into a granulator, granulating, and drying to obtain an intermediate product; Step a3, drying the intermediate product, drying the polyester elastomer, mixing the intermediate product and the polyester elastomer in a mixer, adding the mixture into a double-screw extruder for melt extrusion, cooling the mixture through a cooling water tank, drying the mixture by a blower, granulating the mixture by a granulator, and drying the mixture to obtain the modified PET.
  2. 2. The PET modified atmosphere food packaging material according to claim 1, wherein the thickness ratio of the outer layer, the first adhesive layer, the barrier layer, the second adhesive layer and the inner layer is 8-10:1-2:1-2:1-2:6-8, the maleic anhydride grafted polyolefin elastomer is Bondyram 7109, and the metallocene polyethylene is HPR3518CB.
  3. 3. The PET modified atmosphere food packaging material according to claim 1, wherein the dosage ratio of zinc oxide powder, catalyst, ethylene glycol and terephthalic acid in step a1 is 2-3g:0.3-0.5g:120-150mL:330-350g, the particle size of the zinc oxide powder is 100-150nm, and the catalyst is ethylene glycol antimony.
  4. 4. The PET modified atmosphere food packaging material according to claim 1, wherein the dosage ratio of the master batch to the epoxy chain extender to the antioxidant in the step a2 is 350-400g:2-4g:1-3g:0.3-0.5g, the type of the epoxy chain extender is ADR-4368C, the type of the chain extender is pyromellitic dianhydride, and the type of the antioxidant is 1010.
  5. 5. The PET modified atmosphere food packaging material according to claim 1, wherein the intermediate product and the polyester elastomer in the step a3 are used in an amount ratio of 370-380G to 23-28G, and the polyester elastomer is TPEE G3548.
  6. 6. The PET modified atmosphere food packaging material according to claim 1, wherein the high barrier resin is prepared by the steps of: Mixing methyl phosphonate and dipentaerythritol, stirring, heating, introducing nitrogen for protection, condensing and refluxing to react to obtain phosphorus-containing polyol, drying poly (butylene adipate-terephthalate), adding phosphorus-containing polyol, sorbitol, 1, 4-cyclohexanedimethanol and hydroxyl-terminated polydimethylsiloxane, mixing, stirring, adding into a double-screw extruder, melting and extruding, injecting a cross-linking agent through a side liquid injection port in the extruder, cooling an extruded material through a cold water tank, drying by a blower, granulating by a granulator, and drying to obtain the high-barrier resin.
  7. 7. The PET modified atmosphere food packaging material according to claim 6, wherein the dosage ratio of methyl phosphonate, dipentaerythritol, polybutylene adipate-terephthalate, sorbitol, 1, 4-cyclohexanedimethanol, hydroxyl-terminated polydimethylsiloxane and cross-linking agent is 12-15ml:23-28g:400g:3-4g:2-3g:8-10g:4-5g, the polybutylene adipate-terephthalate is TH801T, the hydroxyl-terminated polydimethylsiloxane is YC-022, and the cross-linking agent is YD-100.
  8. 8. A process for the preparation of PET modified atmosphere food packaging material according to any one of claims 1 to 7, comprising the steps of: Weighing 42-48 parts of modified PET, 7-9 parts of high-barrier resin, 15-20 parts of maleic anhydride grafted polyolefin elastomer, 30-36 parts of metallocene polyethylene, 0.1-0.3 part of antioxidant 1010 and 0.05-0.15 part of erucamide according to parts by weight; Respectively drying the modified PET, the high-barrier resin, the maleic anhydride grafted polyolefin elastomer and the metallocene polyethylene for standby, mixing and stirring the antioxidant and the erucamide, respectively mixing and stirring the antioxidant and the erucamide, the modified PET and the metallocene polyethylene, preparing the mixture through five extruders and a co-extrusion die head, adjusting the rotating speed and the temperature of the five extruders, and sequentially co-extruding the outer layer, the first adhesive layer, the barrier layer, the second adhesive layer and the inner layer according to the layer thickness ratio of 8-10:1-2:1-2:1-2:6-8, and blowing a film and cooling after extrusion to obtain the PET modified atmosphere food packaging material.
  9. 9. The method for producing a PET modified atmosphere food packaging material according to claim 8, wherein the five extruders in the second step are arranged in the order of the outer layer, the first adhesive layer, the barrier layer, the second adhesive layer and the inner layer, the rotation speed and the temperature of the outer layer extruder are respectively 40-50r/min, the temperature of the first adhesive layer extruder is 240-260 ℃, the rotation speed of the first adhesive layer extruder is 5-10r/min, the temperature of the barrier layer extruder is 195-210 ℃, the rotation speed of the barrier layer extruder is 5-10r/min, the temperature of the barrier layer extruder is 165-180 ℃, the rotation speed of the second adhesive layer extruder is 5-10r/min, the temperature of the inner layer extruder is 195-210 ℃, the rotation speed of the inner layer extruder is 30-40r/min, the temperature of the barrier layer extruder is 175-190 ℃, and the inflation ratio of the blown film is 2-2.8.

Description

PET modified atmosphere food packaging material and preparation method thereof Technical Field The invention relates to the technical field of modified atmosphere packaging materials, in particular to a PET modified atmosphere food packaging material and a preparation method thereof. Background In the field of food packaging, modified atmosphere packaging is a common fresh-keeping technology, and by adjusting the gas composition in the packaging, such as reducing the oxygen and increasing the carbon dioxide ratio, the oxidation process in the food can be effectively inhibited and the shelf life of the food can be prolonged, and the modified atmosphere packaging material is generally required to have good gas barrier property so as to keep the specific gas environment in the packaging stable, and simultaneously has certain mechanical strength and good transparency, so that a user can directly observe the state of the food in the packaging. At present, the conventional modified atmosphere packaging materials mainly comprise plastic films such as polyethylene, polypropylene and the like and aluminum foils, and although the conventional materials can keep the freshness of foods to a certain extent, the conventional modified atmosphere packaging materials often face the problems of higher cost and insufficient mechanical properties in the production process of the multilayer composite materials. Therefore, the PET modified atmosphere food packaging material and the preparation method thereof have important significance for improving the quality stability in the food storage and transportation process and meeting the requirements of consumers on food safety and health. Disclosure of Invention In order to overcome the technical problems, the invention aims to provide the PET modified atmosphere food packaging material and the preparation method thereof, which solve the problems of insufficient mechanical property and insufficient gas barrier property of the traditional material. The aim of the invention can be achieved by the following technical scheme: in a first aspect, the application provides a PET modified atmosphere food packaging material, which is obtained by sequentially co-extruding an outer layer, a first adhesive layer, a barrier layer, a second adhesive layer and an inner layer; The material of the outer layer is modified PET, the material of the barrier layer is high-barrier resin, the material of the first/second adhesive layer is maleic anhydride grafted polyolefin elastomer, the material of the inner layer is metallocene polyethylene, the thickness ratio of the outer layer to the first adhesive layer to the barrier layer to the second adhesive layer to the inner layer is 8-10:1-2:1-2:1-2:6-8, the model of the maleic anhydride grafted polyolefin elastomer is Bondyram 7109, and the model of the metallocene polyethylene is HPR3518CB. As a preferred embodiment of the present invention, the modified PET is prepared by the steps of: Step a1, adding zinc oxide powder, a catalyst and ethylene glycol into a three-neck flask provided with a stirrer and a thermometer, mixing and stirring for 30min, transferring into a melt polymerization kettle, adding terephthalic acid, introducing nitrogen for protection, heating to 250 ℃ at a heating rate of 1-2 ℃ under the conditions of 40-90r/min and 50 ℃ for esterification for 2-3h, carrying out vacuum polycondensation for 1h, cooling by a water tank after the reaction is completed, and then feeding into a granulator for granulating to obtain master batch; Step a2, adding master batch and epoxy chain extender into a mixer, wherein the rotating speed of a screw is 70-80r/min, setting temperature subareas respectively, namely, feeding and melting at the temperature of 200-210 ℃ in a first area, mixing and reacting at the temperature of 230-240 ℃ in a second area, plasticizing at the temperature of 250-260 ℃ in a third area, granulating and drying, adding the chain extender and an antioxidant, mechanically stirring for 3-5min, transferring into a double-screw extruder, setting the temperature of the extruder to 220-280 ℃ and the rotating speed of the screw to 60r/min, cooling and shaping through a cooling water tank, adding into a granulator, granulating, drying in a vacuum drying oven at 120 ℃ for 6-12h, and obtaining an intermediate product; Step a3, vacuum drying the intermediate product for 6 hours at 120 ℃, vacuum drying the polyester elastomer for 6 hours at 100 ℃, mixing the intermediate product and the polyester elastomer in a mixer for 3-5 minutes, adding the mixture into a double-screw extruder, feeding and melting the mixture at the temperature of 210-220 ℃ in one area, mixing and reacting the mixture at the temperature of 233-245 ℃ in two areas, plasticizing and extruding the mixture at the temperature of 265-275 ℃ in three areas, cooling the mixture by a cooling water tank, drying the mixture by a blower, granulating the mixture by a granulator, and drying th