Preparation method for multi-layer co-extrusion two-way stretched high-barrier plastic casing

Abstract

The invention discloses a preparation method for a multi-layer co-extrusion two-way stretched high-barrier plastic casing. The preparation method comprises the following steps of: respectively adding raw materials of each layer into an extruder for each layer for melting and plasticizing, wherein the multi-layer co-extrusion two-way stretched high-barrier plastic casing is formed by co-extruding five layers of raw materials; extruding the raw materials by a multi-layer stacked type round mold to form a multi-layer mold blank; slightly blowing and stretching the mold blank, and then immediately and rapidly cooling and molding the mold blank by using cooling water of 5-15 DEG C into a first pipe film; heating the first pipe film in a hot water tank or an infrared heating system to a proper temperature; aerating compressed air to ensure that the mold blank is transversely stretched for a multiplying power of 3 to 5 times and longitudinally stretched for a multiplying power of 2.5 to 3 times to form a second pipe film; putting the second pipe film in an infrared heating barrel for sizing; and rolling a finished product after cooling the second pipe film to a required fold diameter and shrinkage rate by using a vane. Plastic casings prepared by the preparation method have the characteristics of high barrier, high water retention and environmental protection.

Description

technical field [0001] The invention relates to a method for preparing multi-layer co-extruded biaxially stretched high-barrier plastic casings. The high-barrier plastic casings are mainly used for freezing, fresh-keeping and cooking packaging of low-temperature meat products or other foods, and are used for automatic punching and ligation machines or manual Packaging of low-temperature meat products such as sandwiches, sandwiches, and round hams produced by clocking in. Background technique [0002] At present, the plastic casings used to make ham sausages and sandwich square legs on the market include polyvinylidene chloride (PVDC) high-temperature cooking plastic casings, polyamide (PA) and polyolefin (PO) and other resins. Multi-layer co-extrusion Two-way stretch low-temperature cooking plastic casings. Inadequacies of existing packaging: a. Although the barrier properties of PVDC plastic casings are very suitable for packaging applications, there are many defects in pr...

AI Technical Summary

Problems solved by technology

Inadequacies of existing packaging: a. Although the barrier properties of PVDC plastic casings are very suitable for packaging applications, there are many defects in processing performance when using this material. For example, PVDC has thermal instability and requires special equipment for processing. Long-term exposure of PVDC to high temperature environment is prone to produce gel and carbonized particles, resulting in black spots, which will have a certain impact on the production of high-quality products. At the same time, PVDC resin may produce chloride ion monomers during the production process, which is subject to high standards of environmental protection. In some countries and regions, it brings certain difficulties to the production and disposal of waste

b. Using materials such as polyamide (PA) and polyolefin, co-extruded biaxially stretched multi-layer nylon plastic casings are suitable for low-temperature products and have excellent packaging and processing properties, but their barrier properties are lower than PVDC casings. Some areas with unsound cold chains, or products with high barrier requirements, also have certain deficiencies

Images