Water-based Adhesive

Water-based adhesive is a kind of environmentally friendly adhesive which is made of natural or synthetic polymer as adhesive and water as solvent or dispersant instead of toxic organic solvent which is harmful to the environment.Existing water-based adhesives are not 100% solvent-free and may contain limited volatile organic compounds as additives in their water-based media to control viscosity or fluidity.Advantages are non-toxic, non-polluting, non-burning, safe to use, easy to achieve clean production process, etc. Disadvantages include slow drying speed, poor water resistance, poor antifreeze.

Classification of water-based adhesives

1.Manner Classified by Materials:

Polyvinyl alcohol water-based adhesives, vinyl acetate water-based adhesives, acrylic acid water-based adhesives, polyurethane water-based adhesives, epoxy water-based adhesives, phenolic water-based adhesives, silicone water-based adhesives, rubber water-based adhesives.

2.Classified by application:

Water-based adhesives for construction, packaging, automobile, shoes, daily use

3. Classification of water soluble solvent and emulsion binder and modification

1. Water-based polyurethane (APU) adhesive APU is a new type of polyurethane system in which water replaces organic solvent as the dispersion medium, also known as water-dispersed polyurethane, water system polyurethane or water-based polyurethane.Waterborne polyurethane takes water as the solvent, which is pollution-free, safe and reliable, with excellent mechanical properties, good compatibility and easy modification.

APU adhesive is non-toxic and pollution-free, and its high molecular weight enables it to form adhesive film with excellent performance. It has advantages such as low temperature resistance, flexibility, good bonding performance and wide adjustable range of adhesive film properties.Its molecular structure has flexible molecular chains, showing excellent performance of impact resistance, fatigue resistance and low temperature resistance, and also has designability of performance. The adhesive layer is adjustable from flexibility to rigidity, which can meet the bonding requirements of different materials.The synthesis methods of waterborne polyurethane adhesive have been relatively mature, mainly including the following methods:

(1) Introduce some hydrophilic groups into the structure of polyurethane resin to make it self-emulsifying.[1]

(2) Acetone method: high viscosity prepolymer was first prepared, followed by acetone to reduce the viscosity, then hydrophilic monomer was used to expand the chain, which was then added into the water under high speed stirring, and dispersed in the water through strong shear action. After emulsification, the solvent was extracted by vacuum distillation, and then PU water dispersion system was prepared.

(3) sealing and isocyanate method: choose the blocking agent of the right to water sensitive isocyanate end - NCO group protected lose its activity, add extender chain agent and crosslinking agent, a total of milk made from latex when used by a certain temperature and special catalyst demasking, generating - NCO terminal base, chain extender to the preparation of waterborne polyurethane.

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