Curing Mechanism of Reactive Film Adhesive
The reactive film adhesive may be liquid or solid. The reactive film adhesive needs to be a liquid during the bonding process. Only the liquid reactive film adhesive can penetrate the surface of the object to be glued. After soaking, it will become solid again, and then it will have adhesive strength. The process of becoming solid is called solidification.
reactive film adhesiveThere are many kinds. Different types of reactive film adhesives have different curing methods. Different curing methods involve different hot pressing processes. Different hot pressing processes will use different hot pressing equipment.
The reactive film adhesive may be liquid or solid. The reactive film adhesive needs to be a liquid during the bonding process. Only the liquid reactive film adhesive can penetrate the surface of the object to be glued. After soaking, it will become solid again, and then it will have adhesive strength. The process of becoming solid is called solidification.
The curing of hot melt adhesives is a relatively simple form and physical change. A hot melt adhesive is a purely solid adhesive product that does not contain solvents and needs to be heated and melted to make it liquid. After the liquid glue is fully spread and wetted on the surface of the adherend, it will cool down as a whole, and then the hot melt glue will become solid again, so that the adherend forms a certain strength.
The curing of a reactive adhesive is more complicated because its curing will involve a chemical reaction. The reaction mechanism of different types of reactive adhesives is different, but the basic direction is the same. Initially, the liquid uncured adhesive sufficiently wets the adherend, and then under certain conditions, the reactive groups in the adhesive undergo chemical reactions, such as polymerization and cross-linking, to form a thermosetting resin, thereby forming adhesive strength between the adherends. Such as urea formaldehyde resin. Phenolic resins and epoxy resins belong to such adhesives.
Duereactive film adhesiveThe curing method is different, and the sizing process of different adhesives is also very different, so the designed process equipment will also be different. This is an influencing factor that we must consider in the design of the adhesive formulation. The selection and use conditions of the adhesive in the flexible packaging composite process depend on the composite substrate, the use of the composite product and the process conditions of the laminator, mainly a.~ c. commodity types. The type, composition, concentration, coating amount, and drying conditions of the adhesive are interrelated. The key is to select the appropriate solvent type for the polyurethane adhesive and adjust it to a concentration suitable for the speed of the laminator. The drying conditions should ensure that the solvent is sufficiently volatile and dry. The coating amount CW is usually controlled at 1.5~5.0g;M-2. It can be determined by CW = K μρW calculation, where K is the transfer rate, and the empirical value is 1/4~1/6. As a function of coating roll micropores, rubber roll pressure, blade angle, film surface condition, and adhesive viscosity; μ is the coating roll micropore depth; ρ is the adhesive density; and W is the use concentration of the adhesive (% solids). At present, polyurethane adhesives are mainly solvent-based, and the organic solvents used are flammable, explosive, volatile, unpleasant and toxic, which will cause pollution and public hazards when used. Since many countries and departments have promulgated laws and regulations restricting the use of volatile organic compounds (VOC), the use of water instead of solvents as a dispersion medium is environmentally friendly, non-flammable, and can be easily cleaned using existing equipment, so the adhesive has changed from solvent-based to water-based. It has become inevitable.
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