Black/white film for packaging is a novel packaging that has become popular in recent years. In developed countries such as Japan, due to their excellent heat-sealing properties, unique light-blocking and oxygen-blocking functions, and advantages of storage and transportation, and relatively low prices, they have been widely used in the packaging of fresh milk. This trend of foreign packaging milk consumption market should arouse our great attention. Fresh milk black and white film will be the development direction of milk packaging in the next few years. It can substantially reduce the cost of product packaging on the basis of maintaining the fresh milk retention period, meet environmental protection requirements, and avoid the defects of traditional packaging. At present, China's dairy companies use fresh milk packaging black and white film dependent on imports.
Fresh-keeping packaging black and white film is generally composed of three or four layers of different polyethylene and black and white masterbatch co-extruded composite. Its heat seal performance is an important physical indicator of packaging. For milk packaging black and white film, excellent heat sealing performance can ensure that the milk in the automatic packaging line has a wide range of heat sealing temperature, is conducive to increasing the packaging speed; and in the cold storage and transportation process is not broken bags. The black and white film heat seal layer generally uses a metallocene linear low density polyethylene (mLLDPE) with a high degree of branching and a uniform molecular weight distribution to improve the heat seal performance of the black and white film package. Make it suitable for the high thermal bonding strength in the automatic packaging of fresh milk packaging method (vertical molding - filling - heat sealing), will not break bags under the impact of fresh milk, thus ensuring the quality of fresh milk packaging .