PVDC co-extrusion base material film as well as preparation method and application thereof

Abstract

The invention belongs to the field and relates to the field of co-extrusion films, in particular to a PVDC co-extrusion base material film and a preparation method and application thereof. The preparation method comprises the following steps that melt blending is conducted on PVDC resin and EVA resin through an improved single-screw extruder to prepare PVDC and EVA molten resin; then, PVDC and EVA molten resin sequentially passes through a screw and a die head of the single-screw extruder and is attached layer by layer through a center drum, and finally, resin of a multi-layer structure is formed; and when the resin of the multi-layer structure is extruded through a die lip of the die head, a slip agent is added into an inner-layer extruder on line, and then the PVDC co-extrusion base material film is formed through blowing and cooling, a clamping roller, a cutting knife and a winding device. The problems that an EVA resin film is not prone to machine shaping and is difficult to layer are solved, and the film which is high in barrier property, soft, smooth and good in elasticity is provided.

Description

technical field [0001] The invention relates to the field of co-extruded films, in particular to a PVDC co-extruded substrate film and its preparation method and application. Background technique [0002] Co-extrusion technology has developed rapidly at home and abroad in recent years, mostly around the research of EVOH and PA as the core layer. As a multi-layer co-extrusion film with PVDC as the core layer, patent CN 201580004596.5 proposes a heat-shrinkable packaging film production method. When heated , unable to achieve dimensionally stable stretch wrapping function. Patent CN 201401425519.4, patent CN 201410425827.7 and patent 201410427455.1 proposed PVDC co-extruded film, but none of these applications mentioned the ratio of each layer of PVDC and the formula of each layer; a typical feature of its structure is that both sides of the PVDC layer adopt EVA; the inner heat seal layer is directly connected with EVA, there is no secondary inner layer. The adhesive layer E...

AI Technical Summary

Problems solved by technology

[0002] Co-extrusion technology has developed rapidly at home and abroad in recent years, mostly around the research of EVOH and PA as the core layer. As a multi-layer co-extrusion film with PVDC as the core layer, patent CN 201580004596.5 proposes a heat-shrinkable packaging film production method. When heated , unable to achieve dimensionally stable stretch wrap function

Patent CN 201401425519.4, patent CN 201410425827.7 and patent 201410427455.1 proposed PVDC co-extruded film, but none of these applications mentioned the ratio of each layer of PVDC and the formula of each layer; a typical feature of its structure is that both sides of the PVDC layer adopt EVA; the inner heat seal layer is directly connected to the EVA, there is no secondary inner layer

The adhesive layer EVA mentioned in the application has a melting point of 77°C and can only be used below 98°C. If the sterilization temperature is further increased (such as in the range of 100°C-110°C), the film will delaminate, whiten, and the appearance will be severely deformed. Poor packaging appearance, so it cannot withstand the requirements of high temperature sterilization

There is no sub-inner layer, which makes it difficult to reduce the cost control of the structure, and it is impossible to use skeleton resin to balance the flatness problem caused by the difference in density between the inner and outer layers

Polyvinylidene chloride resin has high barrier properties, but it is sensitive to temperature during processing. During processing, equipment heating and rotational shear heat will affect the melting state of polyvinylidene chloride. The gap between the screw groove and the screw barrel , screw operating status will affect the production quality of co-extrusion film, PVDC co-extrusion film in the prior art has quality problems such as carbonization point and thin point

EVA film has good hand feeling, smoothness, good elasticity, and softness, but it is not easy to process and shape during the up-blowing process, and it is not easy to delaminate, and the production cost is high

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