Delayed-tack adhesives

Delayed tack adhesives. These are usually heat activated to achieve the tacky state, after which they can be affixed to any item without a heat source. Most frequently the heating operation plus pressure of application are applied simultaneously, however. The tacky state remains for some time after the source of heat is removed. These are more versatile than the instant tack type, particularly in their application to bottles, tinplate, and plastics, either coated or laminated. Speeds of around 600 per min can be achieved. 

Uses Plasticizer, extender for PVC, CAB, ethyl cellulose, coatings modifier for hot-melt adhesives, aq. adhesives, delayed tack adhesives processing aid for thermoplastics emollient in cosmetics in food-pkg. adhesives... 

T.4 Delayed-Tack Adhesives Table 4.13 Delayed-Tack Adhesives... 

In the packaging field, acrylics are often used for delayed-tack adhesive coatings for labels. Copolymer dispersions of acryUc ester with... 

Other polymers that can provide delayed-tack adhesives include styrene-butadiene copolymers, polyvinyl acetate, polystyrene, and polyamides. Solid (crystalline) plasticizers for these adhesives include dicyclohexyl phthalate, diphenyl phthalate, A-cyclohexyl-p-toluene sulfonamide, and o/p-toluene sulfonamide. Adhesives with different heat-activation temperatures could be obtained because of the range of melting points available. Delayed-tack adhesives have a large number of uses, such as coating paper for labels on bread packages, cans, etc. 

While the rapid setting of hot-melts is usually desirable, there is at least one exception. Labels for bottles and cans are sometimes coated with a delayed tack adhesive, e.g., polyvinyl acetate formulated with a plasticizer... 

Delayed-tack adhesives require activation often by moisture, heat/pressure, or contact. Stamps and envelopes are two examples of moisture activation. A common example of heat-activated adhesive is the one applied to wood edge tapes (veneers). These tapes are used to cover the raw edges of plywood in applications such as shelving. A heated iron is used to press the wood tape against the edge to which it is being apphed. The heat activates the adhesive, which becomes tacky and bonds to the wood edge. 

---