performance:
Domestic and international attention to environmental pollution is very important. The use of solvent-free polyurethane adhesives for composite films can completely solve the problem of solvent-induced pollution. In 1974, German company Henbet first used a solvent-free polyurethane adhesive to make composite packaging materials. In the United States in 1977, solvent-free adhesive accounted for 10%, and in 1980 it accounted for 50%, and it is expected to account for more than 90% in the 1990s: China's use of solvent-free coater equipment is not universal, so the use of solvent-free polyurethane adhesive is less, and there will be no future Solvent polyurethane adhesives have a wide range of development prospects.
1. Coating process
Solvent-free polyurethane adhesives are available in two-component and one-component types. The two-component type has a higher viscosity at the room temperature and a curing agent but still has fluidity and is a semi-solid substance. When compounding is required, the main agent and curing agent are mixed in proportions, placed in a plastic tray with a heat-retaining function, and heated to 50-60° C. to reduce the viscosity to 1 Pa·s or lower, and then passed through with heat insulation. A functional gravure roll is applied to the substrate. After being glued, it is not necessary to heat and dry it through a drying tunnel, because it does not contain any solvent itself, and it can be directly compounded with another substrate.
The use of solvent-free adhesives eliminates the need for exhaust emissions. It does not require large and complex heated blasts and exhaust gas treatment devices. The equipment is simple, raw materials are saved, energy consumption is reduced, maintenance costs are low, and production speeds are increased, so the benefits are significant. At present, most common composite film packaging materials can be produced with solvent-free adhesives, and even high-grade composite film packaging materials resistant to high temperature cooking at 121° C. can be manufactured by this method.
2. Features
1 The environment will not cause pollution due to solvent evaporation, safe operation, and no explosion-proof measures are required;
2 glue coating amount 0.8-2.0g/m2 (usually 1.0g/m2), only half of the solvent type;
3 simple composite process, high composite speed, saving energy consumption;
4 Because there is no need to heat and dry the solvent process, the coater equipment is simple, compact, economical, and the factory floor space is small;
5 There is no problem of food contamination caused by solvent residue and migration;
6 The operating temperature is lower than that of the solvent type and will not cause deformation of the film at high temperatures;
7 high viscosity, need to be preheated during use, the general coating viscosity is 1000-3000mPa · s;
8 The viscosity at room temperature is 4000 mPa·s. When the two components are mixed together, the viscosity can reach 23000 mPa·s within 1 h. Therefore, the two-component solventless adhesive has a short pot life of only 1 h.
attention please:
1. This recipe is a reference recipe for technical personnel to learn and use for reference. Paint Formulation Network shall not be responsible for any loss caused by using this formula for other purposes.
2. Changing raw materials may result in different results. Therefore, it is necessary for you to personally test and evaluate the test results to ensure that the formula meets your needs.
3. It is forbidden to transfer this formula to a third party without authorization from the coating formulation network.
Source: Coating Formulation Network