Tack adhesion

Instant tack adhesives. These are usually used on high-speed automatic labeling machines, as the consistency of heat required to achieve adherence of the label effectively to the substrate (along with its cooling rate) is vital to the success of this method. 

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. 

Piccodiene . [Hercules] Aliphatic hy-drocarbmi resin thermoplastic with balanced tack, adhesive, and cohesive props, when blended with elastomers. 

Series 98. [Syn. Surfaces] Patentedla-tent tack adhesives for factory bonding of automotive parts and pand assemblies, outdoor installation of todSng, sport surfaces, marine and construction materials undtf adverse conditioiis. 

Ultra Light-Weld 9-20269 Wire and Component Tacking Adhesive, Dymax Corp. (undated). 

A certain percentage of resin is almost always incorporated into formulations, with resin content varying from 8 to 25%. Hydrocarbon resins are used most often, but rosin esters, terpenes, and indene resins, which are more heat stable, are also common. Resins provide better flow, hot-tack, adhesion, and wetting characteristics. 

Pressure-sensitive or permanent-tack adhesives are, as their name implies, adhesives that remain sticky even when dried or cured. This means that they are capable of bonding to surfaces simply by the application of light pressure. This makes them arguably the most convenient products available today from the end user s viewpoint and undoubtedly, accounts for the success they enjoy. Although figures are hard to come by, a survey by Business Trend Analysts quoted in the June 1990 issue of Adhesives Age shows that pressure-sensitive adhesives grew from 38% of total adhesive sales in the United States in 1980 to 44.6% in 1988, at an annual rate of 12%, to reach a sales value of 4.9 billion in 1989. 

Features Thennoplastic resist, to acids, alkalis good flex, tear, tack, adhesion props. oxygen and UV It. resist. 

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. 

Tack adhesion measurements were made by curing the polybutadiene gel in a thin film ( 0.5 mm thick) on a plate. A stainless steel probe (8 mm diameter) was brought into contact with the gel film and held for 60 s at a force of 500 g. The probe was pulled away from the gel film at a rate of 0.002 mm/s, while measuring the force-displacement curve. The temperature for the tack measurement was held constant utilizing an environmental chamber. The sample... 

Tackifying resins generally constitute between 8 and 25% of the total adhesive system. The type of resin used influences flow, hot tack, adhesion and substrate ease of wetting. The most commonly used are hydrocarbon resins, such as different petroleum waxes, but many other types (rosin esters, coumarone-indene resins, terpene resins) imparting often some better characteristics, such as a better heat stability, are often used. 

Adh6SiV6 Tack. Adhesives that exhibit adhesive tack are often called pressure-sensitive adhesives (PSAs), since joint strengths depend on the pressure applied during bonding. In practice, PSAs are usually carried on a backing tapes and labels are examples. In order to secure rapid wetting on common surfaces, a PSA must have a creep compliance after 1 s greater than about 10" m /N... 

Probe tests to measure the tack adhesion are accomplished by bringing a probe into contact with the surface of the polymer material being tested under a given force for a specified period of time. The probe is then raised at a constant velocity while measuring the force required to do so. The resulting force versus distance curve provides valuable information on the adhesion properties of the material. The measured adhesion depends on the probe... 

---