Hydrocarbon tackifiers

The increased polarity of the acrylic polymers puts more stringent requirements on the properties of the tackifiers or plasticizers that can be used. The very low polarity additives commonly found in rubber based PSAs are not useful in most acrylic PSA formulations. For example, materials like paraffin waxes, mineral oils, and synthetic hydrocarbon tackifiers have little or no value in most acrylic PSAs. 

Poly dimethylsiloxane emulsion Hydrocarbon tackifier emulsion Rosin tackifier dispersion Carbon black dispersion (oil furnace black)... 

Eastotac [Eastman], TM for hydrogenated C5 aliphatic hydrocarbon tackifying resins. 

Eastotac. [Eastman] Hydrocarbon tackifying resins for adhesives, caulks, and sealants. 

To illustrate the effect of sample thickness, we can compare adhesives to sealants, which in many cases can be viewed as thick adhesives. As the sample thickness is increased, the benefit of the BTZ is clearly demonstrated. In Table 3 a SEBS/hydrogenated hydrocarbon tackifier sealant formulation was prepared as a hot melt and poured into shallow petri dishes. Although both of these polymers have good inherent stability, sealant applications may require extended exposure to UV radiation. The discoloration data show that the BTZ prevents yellowing of the sealant. However, examination of the sealant surface shows surface crazing and cracking when not protected by incorporation of the HALS. The combination of the two classes of light stabilizers provides the best overall performance. 

Figure 13 Stabiliztion of Cs-hydrocarbon tackifier hydroperoxide formation during oven aging at 40°C (104°F).

The most recent development in pressure-sensitive tape manufacture is the development of the hot-melt coating process. Almost aU of the current hot-melt applied adhesives (see also Hot-melt adhesives) are based on SIS thermoplastic rubber, mixed with hydrocarbon tackifier resins and oils in substantial amounts, and an antioxidant in minor amounts. 

The small chain hydrocarbon tackifiers are oligomers with molecular weights in the range of several hundred to 2000 g/mol. They are typically obtained from petroleum feed streams and fall into three general classes. The most common C-5 aliphatic hydrocarbons are cis- and frans-piperylene and isoprene. 

Aliphatic hydrocarbon tackifying resins Aliphatic tackifiers... 

Hydrocarbon tackifiers are used as a less expensive but lower performing alternative to phenolic tackifiers. 

Tackifiers are all low molecular weight materials, ranging from about 300 to about 3000. Some are liquids but the most widely used tackifiers are brittle solids having ring and ball softening points of about 60-115°C. For most effective behavior the tackifier should be close in solubility parameter to the elastomer with which it is blended. Thus aliphatic hydrocarbon tackifiers are not indicated for use with the polar acrylic PSAs. 

To obtain significantly higher quick-stick and peel values in the temperature range of 20°C to ioo°C, acResin DS3532 can be mixed with hydrocarbon tackifier resins, which do not absorb in the UV-C wavelength band, e.g. with Regalite R-gioo. 

The melting point of low-density polyethylene is about 117°C, and its degree of crystallinity will depend on its thermal history. When copolymerized with vinyl acetate molecular regularity is diminished and there is a large reduction in degree of crystallinity. EVA random copolymers containing up to 30% vinyl acetate are used. Further information has been provided by Eastman and Fullhart (1990). The thermal properties of an EVA hot-melt adhesive with an aromatic hydrocarbon tackifier have been examined in detail by Park and Kim (2003). 

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