Water-based dispersion adhesives consist of solid adhesive dispersed in an aqueous phase. These adhesives contain water soluble additives such as surfactants, emulsifiers, and protective colloids that act as links between the solid adhesive particles and the aqueous phase. They prevent the adhesive particles from sticking together and separating during storage. On drying, these additives evaporate or are absorbed into the adhesive. In order to obtain optimum strength and performance, the adhesive must be completely dry. Small amounts of residual moisture combined with residual water soluble additives weaken the film and lower the resistance to moisture and water.
This is particularly important when bonding smooth, non-porous substrates such as metal or plastic. Some water dispersed adhesives have been formulated with the lowest possible amount of stabilizers in order to increase the initial strength or final performance of the adhesive. These formulations may require special pumping equipment due to the lower stability of the liquid adhesive. Dried adhesives are no longer dispersible in water so wet bonding formulations cannot be coated, dried, and then activated with water for bonding. As a result, one substrate must be permeable to water. White glue and carpenters glue based on vinyl acetate polymers are probably the best known water dispersed adhesives. They provide rigid to semi-rigid bond lines and are utilized extensively for bonding wood and wood products, paper, cardboard and corrugated paper.
Water dispersed adhesives based on natural and synthetic rubber and vinyl acetate copolymers provide flexible bond lines and improved adhesion to plastic, metal, rubber and leather compared to vinyl acetate wood adhesives. Water-based dispersion adhesives can be applied by brush, roller, in beads or by spraying. Cleaning of dried adhesive usually requires use of organic solvent and sometimes abrading. Follow manufacturers’ directions for safe handling of solvent. These adhesives are well suited for automated assembly of wide area laminates consisting of water permeable substrates such as film or foil to paper and wood veneer to wood or wood composite.
Good adhesion to cellulose-containing substates such as wood and paper. Primarily used for wood adhesives.
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Good adhesion to many polar plastics.
|Polyacrylates || |
Good aging properties and resistance to media. Primarily used for pressure sensitive adhesives (labels, adhesive tapes), permanent adhesives (e.g. for tiles and floor and wall coverings) and laminating adhesives (e.g. glossy films).
|Polyvinylidene Chloride || |
Physiologically harmless and hence preferred for laminating adhesives used for food packaging applications.
| |Styrene-Butadiene Copolymers
|Laminating adhesives (e.g. aluminum foil on paper) |
|Polyurethanes || |
Usually very good adhesion to many substrates and high adhesion strengths. Applications in the shoe-making industry and for film lamination.
|Polychloroprene ||High elasticity and adhesion strength. Primarily used in the shoe-making industry. |
|Rubber Latexes ||(e.g. Chloroprene Latex). Alternative to solvent-containing contact adhesives. |