First, non-solvent polyurethane adhesive food packaging composite membrane material dry-type composite processing, long since the use of organic solvents as the medium of polyurethane solvent-based adhesive. This kind of adhesive has strong adhesive force. High temperature resistance, resistance to cooking, cold resistance to freeze-resistant packaging, heat curing or room temperature curing, easy operation and so on.
However, the use of a solvent-based adhesive may leave a non-volatile solvent on the composite film, which may cause contamination of the packaged product. At the same time there are volatile organic solvents that pollute the environment and safety issues, coupled with rising solvent prices; the need for energy conservation and other issues, so that the use of solvent-based adhesives is limited.
To overcome this problem, Herberts of Germany in the 1970s. The company uses a polyurethane solvent-free adhesive that is completely free of organic solvents to make food packaging composite film materials in recent years. This process technology has been greatly developed to solve the problems caused by organic solvent adhesives. It has the following advantages over solvent-based adhesives:
1. There is no environmental pollution caused by the volatilization of organic solvents;
2. Solvent evaporation drying section is not required, reducing energy consumption;
3. There is no risk of fire or explosion, solvent explosion protection measures are not needed, and no solvent storage equipment and warehouse are needed. Self-made products do not have the problem of residual solvent damage, and eliminate solvent attack on printing inks.
4. Because it does not contain organic solvents, it eliminates the effects of the composite substrate being susceptible to solvent and high-temperature drying being damaged, so that the dimensional stability of the composite membrane structure is good;
5. The equipment is simple and the floor space is small, saving investment.
The technology of solvent-free composite manufacturing of composite film packaging materials, after decades of development has become mature technology, this new processing technology will be prominent with its obvious superiority; will gradually be recognized and accepted at home. At present, many domestic adhesive manufacturers are investing more manpower and resources to research and develop solvent-free adhesives. It is hoped that China's flexible packaging industry organizations and packaging companies can attach importance to and jointly promote the application and development of solvent-free adhesives on composite film packaging materials.
Second, solvent-free composite technology With the continuous development of composite technology and composite materials such as films, adhesives, solvent-free composite technology is being more and more widely used in flexible packaging. Although solvent-free compounding is less widely used in China than solvent-based compounding, it has advantages in terms of environmental protection, cost reduction, improved compounding speed, product-free solvent residue, etc., and all aspects of solvent-free composite products. It is gradually approaching or reaching the level of solvent-based composite products. Therefore, the development of solvent-free composite processes will form a trend, and this technology has a wide market prospect.
Solvent-free compounding has an absolute advantage over solvent-based compounds in terms of environmental protection, cost, and compound speed. For composite product performance, there is no essential difference between heat-seal strength and peel strength in both solvent-free and solvent-based composites.
Solvent-free compounding can replace some of the more demanding solvent-based composite products, such as pasteurized composite membranes. In the case of demanding cooking products and the content conditions are more severe, solvent-free compounding cannot replace solvent-based compounding. Nonetheless, solvent-free compounding can be used for most composite products.
The vigorous promotion of solvent-free composite technology is a responsibility for domestic plastic color printing companies. Of course, due to lack of propaganda and other reasons. The promotion of this technology requires a process, but as long as we dare to challenge it, it will eventually be used by us.
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