A multi-layer improved heat-shrinkable plastic wrap/bag

Abstract

The invention relates to a multilayer improved thermal shrinkage preservative film / bag and a base material composition thereof, belonging to the technical field of preservative films. The multilayer improved thermal shrinkage preservative film / bag is characterized in that according to the formula, the base material composition comprises the following materials in percentage by weight: 60%-90% of ethanediol modified polyethylene glycol terephthalate copolymers, 5%-20% of ethylene acrylic acid copolymers or maleic anhydride graft polymers and 5%-20% of a soft improver; the preservative film is prepared by adopting the base material composition of the multilayer improved thermal shrinkage preservative film as a resin-based functional layer (4), and at least one functional layer and at least one adhesive layer are co-extruded on the upper surface and the lower surface of the resin-based functional layer (4) so as to form a multilayer layered structure. The multilayer improved thermal shrinkage preservative film / bag disclosed by the invention contains no chloride, is free of crosslinking and has excellent puncture resistance and oxygen and water vapor obstruction property.

Description

technical field [0001] The invention discloses a multi-layer improved heat-shrinkable preservative film / bag, which belongs to the technical field of preservative film. Background technique [0002] The existing multi-layer cling film produced with polyamide as the main resin raw material for the surface layer and functional layer, although it is very convenient to exert its hot water shrinkage and moderate barrier properties, it is greatly affected by the ambient temperature and humidity, and it is prone to preservation at room temperature. Film and bag curling and warping phenomenon. After the outer layer of polyamide material absorbs moisture and absorbs moisture, the moisture will remain and will freeze during freezing and refrigeration, resulting in the decrease of the mechanical properties of the plastic wrap and the bag, which will become brittle and hard, and the gloss will also decrease. At the same time, the The plastic wrap has poor dimensional stability, poor acid...

AI Technical Summary

Problems solved by technology

Although these heat-shrinkable film bag products have promoted the packaging, storage, transportation and circulation of meat food, they all face the problem of how to improve product defects, improve the comprehensive utilization efficiency of product waste recycling, save resources, and reduce or eliminate environmental pollution.

[0003] The various raw materials used in multi-layer heat shrinkable film have their unique performance advantages and weak physical properties that should be continuously improved. The advantages and functions of multi-layer co-extruded plastic wrap film complement each other. , Good functional resins suitable for printing processing and anti-blocking properties, such as polyamide nylon materials, high strength and good heat resistance, but are greatly affected by ambient temperature and humidity, and cling film and bag curling are prone to occur at room temperature Warping phenomenon, after the outer polyamide material absorbs moisture, the moisture will remain and will freeze during freezing and refrigeration, resulting in the deterioration of the mechanical properties of the plastic wrap and the bag, which will become brittle and hard, and the gloss will also decrease. In addition, the polyamide material is used for The resin base in the multi-layer shrink wrap film has poor dimensional stability, poor acid resistance, and difficulty in granulating and recycling waste packaging due to the influence of ambient temperature and humidity. The user market requires improvement of defects; although polyester materials have excellent optical properties, they have good cold resistance and heat resistance. , Excellent weather resistance, good mechanical properties, wear resistance, low water absorption, excellent moisture resistance and waterproof performance, good water vapor resistance, excellent dimensional stability of small products affected by ambient temperature and humidity, non-toxic and environmentally friendly, recyclable, but high rigidity, is thermoplastic The material with the highest hardness has poor flexibility, poor corona resistance, and is not resistant to alkali. The weak physical properties need to be improved by resin to be better applied to multi-layer shrink films; materials such as metallocene polyethylene or metallocene polypropylene, Although the melt temperature of the long-chain branched polymer in metallocene polyethylene is easy to process, but the short-chain branched metallocene polyethylene has high melt viscosity and low melt strength, so it is difficult to blow film and prone to film bubble rupture Or produce shark skin pattern, excessive blown film speed will cause melt fracture, and excessively high melt temperature will also adversely affect the co-extrusion of heat-sensitive materials in multilayer films; the gas barrier layer is generally Ethylene / vinyl alcohol copolymer, ethylene / vinyl alcohol copolymer has excellent gas barrier properties, high transparency, anti-ultraviolet, good processability, mixed scraps with propylene polymer and ethylene polymer can be recycled; ethylene / vinyl alcohol copolymer In multi-layer co-extrusion, it can be made into an extremely thin gas barrier layer, so the cost is relatively low, but the rigidity and high hardness need to be improved by co-extrusion flexibility. When used in a single layer, the water vapor barrier property is poor and the price is relatively expensive; polyamide Oxygen barrier property is 4-5, which is not ideal for cold fresh meat food packaging that requires high barrier property. However, the cost and price of special polyamides such as nylon MXD6 and nylon 6I / 6T are relatively high, and the advantages and disadvantages of polyamide materials have been mentioned above. It has been stated that it must be emphasized here that polyamide is easy to absorb moisture. When the moisture content of the resin exceeds 0.1%, bubbles will appear in the polyamide film layer, and the gloss will also decrease, and the moisture will remain in the extrusion process. Accelerates the degradation of polyamide polymers, resulting in the decline of mechanical properties of plastic wrap and affecting production; however, the resin base in the existing multi-layer shrink film structure is generally polyamide resin; polyvinylidene chloride and other copolymers containing vinylidene chloride are difficult to process , It is difficult to recycle scraps, electronic cross-linking and combustion disposal will produce chlorine-containing gas, and polyethylene and ethylene vinyl acetate copolymers that are co-extruded with polyvinylidene chloride must be cross-linked by high-intensity electron radiation to improve their toughness. The strength and heat shrinkage of the layered film make it difficult to recycle; the heat-sealing layer is generally made of polyethylene series, but the heat resistance is insufficient, the gas barrier property is poor, and it has electrification. The addition of antistatic agents and other additives will affect the heat-sealing quality. Affected; Ethylene / vinyl acetate copolymer with high acetic acid content has a sour odor, poor slipperiness, poor moisture resistance, and poor gas barrier properties, so it is not suitable as a heat-sealing layer for aromatic flavor meat food packaging

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