With the introduction of social economy, the flexible packaging industry has also developed rapidly. With the improvement of living standards, people are more and more uneasy about food safety and health. Almost all plastic packaging products are used for food display, so the safety and environmental protection issues of plastic display are closely related to the health of consumers. At present, the food packaging composite film in China is simply composited with solvent-based glue to ensure that there will be no solvent volatilization and a small amount of solvent residue during the composite process. Food packaging luggage with good solvent residues will definitely cause the luggage to smell bad and cause the food to spoil. Solvent evaporation during the compounding process not only pollutes the environment, but also endangers the health of field workers. Therefore, how to reduce the total amount of solvent volatilization and solvent residue through the composite method of food packaging, while ensuring product quality, reducing costs, improving corporate profits, and finding ways to meet the environmental protection and health of food packaging. , and conform to the development of the organization itself, and become the purpose of domestic food packaging enterprises to learn.
As a contributor to the field of flexible packaging adhesives, winlong has finally developed an environmentally friendly and hygienic food packaging composite adhesive-water-based composite adhesive after years of research and long-term experimental exploration. The techniques are described below.
Compounding mechanism
Ordinary water-based adhesives refer to composite adhesives that use water as the main solvent and can be used directly. Almost all water-based adhesives are polyacrylic or polyurethane material polymers and have good temperature and media resistance. The water-based acrylic emulsion has good affinity with most composite substrates, strong adhesion, and a wide mucus surface. It is an excellent water-based glue. Acrylate monomers are easily polymerized, and the high molecular weight polymers ensure high shear durability and initial peel strength, which in turn give them high initial strength and can be easily cut into bags without curing. The principles of filmmaking are presented in clause 1.
Water based glue operating conditions
The process of water-based glue is basically the same as that of solvent-based glue, but there are some special conditions that need to be met, or some aspects of work need to be carried out in strict accordance with the operating conditions.
(1) Line spraying tool: Above 160 lines, be sure to choose a dense and shallow laser engraving roller, which can ensure that the glue can be better used in the film more easily. This is much more demanding than solvent-based adhesives. The main reason is that the amount of water-based adhesive is small. The general application intensity is about 2mg/m2. Too much glue will give the appearance of the composite resin film.
(2) Drying tunnel temperature: 75℃-80℃-85℃, wind speed: above 8.0m/s. Moisture evaporation is absolutely critical for water carrier adhesives, so temperature and wind speed must ultimately be maximized to deal with this dilemma. When considering the tolerance of the film and process, try to follow the recommended conditions.
(3) Composite temperature: above 60℃, composite pressure: above 4kg, as large as possible. In order to ensure the first strength increase of the water carrier based adhesive, the compounding temperature and pressure must be increased to ensure that the polymer microspheres can be easily flattened quickly between the composite membranes, resulting in a significantly better state to ensure that the composite membranes Can be cut directly into bags soon after processing.
(4) Scraping tool: also known as flattening roller, try to use a coating tool with reverse rotation. We have observed in actual production that the reverse flattening roller has a great influence on the overall appearance of the composite film, and the appearance can be optimized by changing the speed.
