Tackifying agent

Hydrocarbon resins comprise a range of low-molecular-weight products (M < 3000) used as adhesives, hot-melt coatings, tackifying agents, inks, and additives in rubber. These include products based on monomers derived from petroleum as well as plant sources. The petroleum-derived products include polymers produced from various alkenes, isoprene, piperylene, styrene, a-methylstyrene, vinyltuolene, and dicyclopentadiene. The plant-derived products include polyterpenes obtained by the polymerization of dipentene, limonene,... 

These adhesives form a special class of adhesives, in which the adhesive mechanism is derived mainly from the formulation of the components. PSAs are highly viscous liquids that contain, in addition to a polymeric skeleton, special tackifying agents that gives them their adhesive character. The tackifying agents are what cause contact adhesives to stick immediately when pressed onto a plastic surface. This immediate adhesion is called tack. 

These substances determine the heat and moisture resistance of the adhesives, but are also responsible for the effectiveness of the tackifying agents. Pure acrylates are among the best PSAs. 

The most widely used thermoplastic polymer is the ethylene—vinyl acetate copolymer, which is obtainable in a wide range of molecular weights as well as in a variety of compositions. Often flexibilizers or plasticizers are added in order to improve both the mechanical shock resistance and the thermal properties of the adhesive. Polybutenes, phthalates, and tricresyl phosphate have been used as plasticizers. Tackifying agents can also be added. Because hot-melt adhesives are frequendy ethylene-based, they are subject to oxidation if, as in a typical situation, the adhesive sits in an applicator for long periods before use. Thus, antioxidants such as hindered phenols are often used, as are fillers. Fillers are added to opacify or to modify the adhesive s flow characteristics, as well as to reduce cost. Wax is also a very important component. Wax alters surface characteristics by decreasing both the liquid adhesive s surface tension and its viscosity in the melt. Upon solidification, however, the wax acts to increase the strength of the adhesive. Both paraffin and microcrystalline wax are used (see Waxes). 

Other hot melts are based on low molecular weight polyethylene, combined with tackifying agents. These tend to be lower in cost and performance than the EVA-based hot melts, and they are used primarily with paper packaging, such as cartons and multi-wall bags. Atactic PP can also be used as the base for hot melt adhesives. Pressure-sensitive hot melt adhesives for tapes and labels often employ thermoplastic elastomers, consisting of block copolymers of styrene and butadiene or isoprene. 

Brinkman BG, Cadenas C, Phillips R, Arnold A, Bowman K. Evaluation of tackifier agents for resin transfer molding. In 40th international SAMPE symposium. May 8—11, 1995 1995. pp. 1523-30. 

Uses Solvent and thinner for paints, varnishes, other coatings dry-cleaning solvent spot and stain removal solvent in textile industry mfg. of pesticides, cleaners, aerosol prods. metal and leather cleaning/ degreasing extraction of fats and oils in rubber cements and polishes tackifying agent for rubber... 

The most prominent use of MQ resins is as the tackifying agent for silicone pressure-sensitive adhesives (PSA) (523-525). The other main component of silicone PSA is a silicone gum. This mixture of MQ resin and silicone gum is applied to a tape backing such as polytetrafluoroethylene (FIFE) or poly(ethylene... 

Polymerizable monomers produced by plants such as terpenes and unsaturated plant oils (Chart 1, Group A) are one of the most desired groups. Of these, terpenes are the most important class from a commercial standpoint [28]. These polymers find widespread use as tackifying agents in adhesives. The cationic polymerization of plant oils (e.g., soybean oil) is known but the resultant materials do not possess useful physical properties and therefore they are typically copolymerized with petroleum-derived monomers (e.g., divinylbenzene, dicyclopentadiene) [29-35]. 

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