Polyethylene heat-shrinkable film with hdpe as matrix resin and its manufacturing method

Abstract

The invention discloses a polyethylene thermal-shrinkage film taking HDPE (High Density Poly Ethylene) as a matrix resin and a manufacturing method thereof. The polyethylene thermal-shrinkage film is characterized in that the structure is a 5-layer or above 5-odd-layer symmetrical film blowing structure; the thickness of a core layer which is located on the middlemost position is at least 2 times of the thickness of any other layers; the total mass content of the HDPE in the polyethylene thermal-shrinkage film is 35%-50%; the core layer contains at least the HDPE from LDPE (Low Density Poly Ethylene), LLDPE (Linear Low Density Poly Ethylene) and HDPE; the mass content of the HDPE in the core layer is 90%-100%; the surface layer at least contains the LDPE from the LDPE, LLDPE, m-LLDPE (Metallocene Catalyzer Linear Low Density Poly Ethylene) and HDPE; and the mass content of the LDPE in the surface layer is 80%-100%. The polyethylene thermal-shrinkage film can acquire ideal penetration-wearing property and shrinking percentage; under the condition of maintaining proper film deflection, heat sealability, optical property and shrinking percentage, the film is thinner and lower in cost; and the film is strong in economic benefit and environmental protection benefit.

Description

technical field [0001] The invention belongs to the technical field of plastic films, and relates to a polyethylene heat-shrinkable film and a manufacturing method thereof. Background technique [0002] The polyethylene resin used to produce polyethylene heat shrinkable film is divided into LDPE, LLDPE, m-LLDPE, HDPE, and its characteristics are as follows: [0003] [0004] At present, the thickness of polyethylene heat shrinkable film is 35-85μm, and the thickness of <60μm is mainly used for light packaging such as food and daily chemicals, and the thickness of 50-70μm is mainly used for the packaging of beverages and beer with a total weight of <8kg; 70-85μm is mainly used for packaging Beverages and beer with a total package weight > 8kg. The shrinkage rate of polyethylene heat shrinkable film is generally required to be 10-25% in the transverse direction and 65-80% in the longitudinal direction. [0005] 1. The formulation process of polyethylene heat shri...

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Problems solved by technology

[0016] The existing production process, whether it is a single-layer formula or a three-layer formula, cannot use low-cost, high-stiffness HDPE as the matrix resin, because the BUR of the traditional production process reaches 3.5, and it is difficult to blow out stable film bubbles , HDPE due to the characteristics of low transverse shrinkage, resulting in a significant decrease in transverse shrinkage and can not meet the film requirements, especially the requirement of 15-20% of medium shrinkage and 20-25% of high shrinkage, and these two types are currently The mainstream market of polyethylene heat shrinkable film accounts for the vast majority

[0017] Moreover, increasing the HDPE content in the formula will greatly reduce the puncture resistance of the film, which will lead to a substantial increase in the rate of package breakage during transportation. In order to make up for this defect, m-LLDPE must be added to improve the puncture resistance, which in turn The content of LDPE with good shrinkage is reduced, resulting in the continued shrinkage of transverse shrinkage, and the technical solution of increasing the content of low-cost HDPE cannot be implemented

[0018] In order to reduce the amount of plastic used and achieve the purpose of energy saving and environmental protection, the market needs a thinner and lower-cost polyethylene heat shrinkable film, which requires no reduction in shrinkage, stiffness, puncture resistance, and optical properties. The production process is obviously insoluble

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