Tackifier resins rubber-based adhesives

Some rubber base adhesives need vulcanization to produce adequate ultimate strength. The adhesion is mainly due to chemical interactions at the interface. Other rubber base adhesives (contact adhesives) do not necessarily need vulcanization but rather adequate formulation to produce adhesive joints, mainly with porous substrates. In this case, the mechanism of diffusion dominates their adhesion properties. Consequently, the properties of the elastomeric adhesives depend on both the variety of intrinsic properties in natural and synthetic elastomers, and the modifying additives which may be incorporated into the adhesive formulation (tackifiers, reinforcing resins, fillers, plasticizers, curing agents, etc.). 

Rosins and rosin derivatives. The resins more commonly used in rubber base adhesives are rosin esters, particularly glycerol and pentaerythritol esters, as well as rosins modified by disproportionation and hydrogenation. The glycerol ester of hydrogenated rosin has been reported to be an excellent tackifier for polychloroprene adhesives (see pp. 344-357 in [17]). 

Chem. Desarip. Modified dehydrogenated (disproportionated) rosin CAS 8050-09-7 EINECS/ELINCS 232-475-7 Uses Thermoplastic resin in hot-melt-applied adhesives and coating tor paper and paperboard substrates as tackifier and processing aid tor rubber-based adhesives and molding compds. emulsifier tor emulsion polymerization plasticizer, softener, tackifier tor use in contact with food Features Pale, oxidation-resistant si. retards cure Pro rties USDA Rosin N solid, flakes sol. in alcohols, esters, ketones, min. spirits, and aromatic hydrocarbons dens. 1.058 kg/l R B soften, pt. 73 C flash pt. (COC) 209 C acid no. 154 sapon. no. 159... 

Chem. Descrip. Glyceryl rosinate CAS 8050-31-5 EINECS/ELINCS 232-482-5 Uses Resin for lacquers, varnishes, adhesives wax modifier tackifier in pressure-sensitive rubber-based adhesives, in solv. and emulsbn types, in EA/A resin wax hot-melt adhesives and coatings modifier (contributes hardness, rapid drying, and resistance to water and alkali) in varnishes improves clarity as a wax modifier Features Pale thermoplastic... 

Elastomeric adhesives typically contain an elastomer and a tackifying or modifying resin as key components, but in general, other ingredients are also included. The formulation of rubber-based adhesives may contain nine, or even more, different components (Table 1). Typical formulations of various types of adhesives are given in Tables 2-5. 

Tackifiers and modifiers are generally added to improve the adhesive performance of rubber-based adhesives, although other properties (viscosity, open time, tack) are also modified. Resins used in rubber-based adhesive formulations have the following characteristics ... 

Formulation. Unlike the natural rubber pressure sensitive adhesives, acrylic adhesives are often supplied in a ready-to-use form. Natural rubber adhesives require time-consuming and costly mastication of the rubber followed by dissolving in solvent. In addition, they must be formulated with a tackifier resin and antioxidants, neither of which is required with an acrylic adhesive. The acrylic adhesives are known for their good UV and oxidative stability while the rubber-based adhesives, because of their chemical unsaturation, are poor in these properties. In general, tackifiers are not required with acrylic adhesives as tack can be designed into the polymer by the proper choice of... 

NR, styrene-butadiene mbber (SBR), polybutadiene rubber, nitrile mbber, acrylic copolymer, ethylene-vinyl acetate (EVA) copolymer, and A-B-A type block copolymer with conjugated dienes have been used to prepare pressure-sensitive adhesives by EB radiation [116-126]. It is not necessary to heat up the sample to join the elastomeric joints. This has only been possible due to cross-linking procedure by EB irradiation [127]. Polyfunctional acrylates, tackifier resin, and other additives have also been used to improve adhesive properties. Sasaki et al. [128] have studied the EB radiation-curable pressure-sensitive adhesives from dimer acid-based polyester urethane diacrylate with various methacrylate monomers. Acrylamide has been polymerized in the intercalation space of montmorillonite using an EB. The polymerization condition has been studied using a statistical method. The product shows a good water adsorption and retention capacity [129]. 

Styrene Copolymers. The so-called thermoplastic rubbers based on styrene-butadiene-styrene and styrene-isoprene-styrene block copolymers can be used for hot-melt adhesives, particularly when extended with tackifying resins and oils. They can be made into pressure-sensitive adhesives, as melts with low viscosity—being applied from fine spinnerets which are oscillated to make a... 

Elastomers used in water-based systems include various rubber latices, especially natural rubber and SBR, and occasionally, polychloroprene. The bulk of the market in water-based adhesives is now held by acrylic dispersions. Although these are designed for use without modification, it is normal to formulate, especially by addition of tackifiers. Commonly used tackifying resins include soft resins, or hard resins in solution, which may... 

Uses Tackifier resin for water-based adhesives and sealants based on acrylic, S/B, nat. rubber, neoprene, and PVAc, esp. for pressure-sensitive adhesives, and for coatings Features Solv.-free... 

Chem. Descrip. Aromatic hydrocarbon resin Uses Tackifier in elastomer-based solv., water, and hot-melt sealants and adhesives processing aid, reinforcing agent in rubber compd. and extruding applies. in metallic cold-cut paints food-pkg. and processing applies. 

Hydrogenated rosin Methyl rosinate Methylstyrene/vinyltoluene copolymer Paraffin, chlorinated Pentaerythrityl hydrogenated rosinate Pentaerythrityl rosinate Polybutene Polydipentene Polyvinyl methyl ether Rosin Sorbeth-20 Terpene resin tackifier, adhesives EVA-based Dipentene-styrene resin tackifier, adhesives rubber-based Dipentene-styrene resin tackifier, amorphous polyolefins C5 hydrocarbon resin, aliphatic tackifier, antifouling paints Methyl hydrogenated rosinate tackifier, butyl rubbers C5 hydrocarbon resin, aliphatic tackifier, caulks C5 hydrocarbon resin, aliphatic tackifier, cement... 

For PSA s with the resin-rubber systems, several types of latexes are being used in place of rubber for the waterborne adhesives. Styrene-butadiene (102) latexes and natural rubber latexes (103) have been mentioned in the literature. In addition, waterborne tackifiers (104) have been developed for PSA s. A family of emulsifier-free, high solids, completely freeze-thaw stable tackifying resins was developed by Rohm and Haas. The new products are viscous resins based on the replenishable tail-oil rosin. The... 

There have been very few studies reported on the viscoelastic properties of rubber-resin pressure sensitive adhesive systems. In 1973, M. Sherriff and co-workers (1) reported on the effect of adding poly (j3-pinene) resin to natural rubber. Based on a G master curve, they showed that the resin shifted the entry to the transition zone to a lower frequency and reduced the modulus in the rubbery plateau. G. Kraus and K.W. Rollman (2) reported in 1977 on their study of resins blended with styrene-isoprene-styrene block copolymers. They showed that the addition of a resin increased the glass transition temperature of the rubbery mid-block and decreased the plateau modulus. Accordingly, a satisfactory tackifying resin should produce these changes. 

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. 

It is said that a pressure-sensitive adhesive always must be composed of a high-polymer base resin, which determines cohesion and specific adhesion, and of tackifying resins (tackifiers). In some systems, the tackifier may be replaced by low molecular mass fractions of the base polymer. To increase cohesion, the base resin in some systems is cross-linked or, in the case of rubber-based pressure-sensitive adhesives, vulcanized after application. 

Block copolymers with incompatible blocks which are able to microphase separate are good candidates for PSA properties. Indeed, blends of ABA triblocks and AB diblocks, where the rubbery midblock of the ABA is the majority phase and the glassy endblocks self organize in hard spherical domains and form physical crosslinks, are widely used as base polymers for PSA. The actual adhesives are always compounded with a low molecular weight tackifier resin able to swell the rubbery phase and dilute the entanglement network. Linear styrene-rubber-styrene copolymers, with rubber being isoprene, butadiene, ethylene/propylene or ethylene/butylene, are the most widely used block copolymers in this category. 

Tackifying resins must be added to latex in the form of an aqueous dispersion. These are available commercially, although at present the choice is not as wide as with solid resins. Considerable expertise is required to formulate resin dispersions, as it is important that the particle size be small, preferably less than 1 fxm in diameter. Large particle dispersions may result in reduced tack and delay in attaining equilibrium between rubber and resin in the adhesive film. The most popular resins for natural rubber are based on rosin esters, and these may be extended with cheaper synthetic hydrocarbon resins depending on the adhesive properties... 

Traditionally, PSAs are rubber-based formulations with hydrocarbon resins included as tackifiers. But PSAs based on UV/radiation use new and evolving technology to reduce or eliminate solvents or dispersible mediums. Even though packagers may find it more economical to use water-borne, reactive or hot-melt adhesives, industry researchers predict that UV/radiation-cured adhesives will grow at a rate of 10% a year. 

Tackifiers are used in formulating rubber based on adhesives to improve the tack property. Tackifiers are low molecular weight compounds with high Tg. There are two classes of tackifiers the rosin derivatives and the hydrocarbon resins. The rosin derivatives include the rosins, modified rosins, and rosin ester. The hydrocarbon resins consist of low molecular weight polymers derived from petroleum, coal, and plants. The miscibUity between tackifiers and the adhesives is important to choose a tackifier. The viscoelastic property of adhesives can be modified by blending of a miscible tackifier. 

Most PSAs are based on natural rubber. Rubber by itself has very low tack and adhesion to surfaces thus requires addition of tackifying resins based on rosins, petroleum, or terpenes. Hydrogenated resins are... 

Tackifier An additive intended to improve the stickiness of a cast adhesive film, usually a constituent of rubber-based and synthetic resin adhesives. 

Oxidized castor oils are excellent nonmigrating, nonvolatile plasticizers (qv) for ceUulosic resins, poly(vinyl butyral), polyamides, shellac, and natural and synthetic mbber (see Rubber, natural). The high viscosity products are also used as tackifiers in gasket compounds and adhesives (qv) because of good oil and solvent resistance. They also serve as excellent pigment grinding media and as a base for inks (qv), lubricating oils, and hydrauHc oils (62). 

Butyl phenolic resin is a typical tackifier for solvent-borne polychloroprene adhesives. For these adhesives, rosin esters and coumarone-indene resins can also be used. For nitrile rubber adhesives, hydrogenated rosins and coumarone-indene resins can be used. For particular applications of both polychloroprene and nitrile rubber adhesives, chlorinated rubber can be added. Styrene-butadiene rubber adhesives use rosins, coumarone-indene, pinene-based resins and other aromatic resins. 

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