TYPICAL FORMULATION INGREDIENTS AND PROPERTIES
PROCESSING
Once the base emulsion polymer is obtained, it is then mixed with all other liquid ingredients and additives except for the fillers. When this blend is complete, add the filler slowly, blending well between all additions. Generally, high shear mixers are sufficient to produce a heavily bodied sealant.
APPLICABLE BASE POLYMER PROPERTIES
Waterborne polyvinyl acetate adhesives have the same base latex resin that is used in wood glues. These adhesives provide a low to medium performance, inexpensive adhesive that dries to a relatively rigid material. A typical formulation consists of polyvinyl acetate latex, filler, plasticizer (for improved flexibility) and water. Since these adhesives set by evaporation, they shrink on drying more than 100% solids adhesives.
RESULTING PROPERTIES
A typical waterborne polyvinyl acetate adhesive formulation is shown above. This is the type of product that is commonly used for bonding paper and paperboard. This particular adhesive has found acceptance in the bookbinding industry.
Without any plasticizer PVAc adhesives will become hard and brittle on aging. The addition of a plasticizer such as dibutyl phthalate will soften the PVAc polymer and eliminate embrittlement.
TIPS & TRICKS
Emulsion polyvinyl acetate adhesives can be difficult to apply due primarily to their low solids content and foaming characteristics. Often fillers and antifoaming agents are employed to solve this problem.
With emulsion adhesives, the water carrier provides excellent penetration into the paper. This generally results in superior flex and pull strength characteristics and makes cold emulsion adhesives the most durable method of adhesive bookbinding. As a result, emulsion adhesives are often used in traditional binding even though they provide a much slower process t