Aromatic resin tackifiers

In the earlier art, there was some consideration that partial incompatibility of the tackifier resin with the rubber was responsible for the appearance of tack, but this no longer is seriously held in light of continuing studies by many investigators. Aubrey [38] has addressed this in his review of the mechanism of tackification and the viscoelastic nature of pressure sensitive adhesives. Chu [39] uses the extent of modulus depression with added tackifier as a measure of compatibility. Thus in a plot of modulus vs. tackifier concentration, the resin that produces the deepest minimum is the most compatible. On this basis, Chu rates the following resins in order of compatibility for natural rubber rosin ester > C-5 resin > a-pinene resin > p-pinene resin > aromatic resin. 

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. 

Polyisoprene can be UV or e-beam cured [43,44]. The 3,4 units are particularly prone to crosslinking at low dose [45]. SIS and SBS are also crosslinkable, even conventional linear materials with low vinyl content however, small amounts of liquid trithiol or triacrylate compounds speed cure dramatically [44]. Like UV, e-beam cure is strongly affected by tackifier choice. Hydrogenated, non-aromatic resins provide much less interference with cure [36,37]. 

Petroleum resins are a by-product of oil refining. Like hydrocarbon resins, a range of grades are produced. Aliphatic resins, which contain oligomers of isoprene, tend to be used as tackifiers, whereas aromatic resins, which also contain high levels of dicyclopentadiene, tend to be classed more as reinforcing systems. 

These studies demonstrate that in selecting resins to tackify either natural rubber or styrene-butadiene rubber, consideration must be given to the resin structure. An aliphatic resin is more likely to be compatible with natural rubber, while an aromatic resin would be compatible with styrene-butadiene rubber. 

The next series of Figs. 5-7 illustrate the use of a relatively new aromatic modified terpene resin as a tackifier for natural rubber latex. Again, the properties of probe tack, quick stick, peel and shear adhesion were measured for various rubber/resin ratios. We observe that this resin tackifies the natural rubber latex quite well, yet the curves are substantially different from those generated with the beta-pinene resin emulsion. These differences can be attributed to differences in solubility parameter (caused by compositional differences) and molecular weight and distribution of the two resins. 

Polyken Tack and Shear Adhesion of a Carboxylated SBR Latex Tackified with an Emulsion of the Glycerol Ester of Hydrogenated Rosin or a Modified Cg Aromatic Resin Emulsion... 

A more quantitative indication of compatibility can be obtained with solvent or hot melt cloud point tests. The solvent cloud point tests are based on the idea that resins will be compatible with elastomers of similar chemical nature. Thus aliphatic resins will be effective tackifiers for aliphatic elastomers such as natural rubber, while aromatic resins are needed for aromatic elastomers such as SBR. Some resins, e.g., rosin esters, will be compatible with many different types of elastomers. Solvent cloud point tests are carried out in three solvent systems which represent aliphatic, aromatic, and polar systems. The solvent blends used by Hercules are ... 

Tackifying resins also come from petroleum feedstocks. These are broadly dassified as aromatic and aliphatic resins. The aromatic resins are based upon such materials as styrene, a-methyl styrene, methyl indene, indene, coumarone, and dicy-dopentadiene. Aromatic resins are sometimes called C-9 resins. The materials in various combinations are polymerized by much the same process as the pinenes. Some of the aliphatic resins are also called C-5 resins, as these are based upon pen-tene, cydopentene, ds- and tram-piperylene, isoprene, 2-methyl butene-2, and dicydopentadiene. An abbreviated list of conventional taddfying resins is shown in Table 1. 

Pressure sensitive adhesives typically employ a polymer, a tackifier, and an oil or solvent. Environmental concerns are moving the PSA industry toward aqueous systems. Polymers employed in PSA systems are butyl mbber, natural mbber (NR), random styrene—butadiene mbber (SBR), and block copolymers. Terpene and aUphatic resins are widely used in butyl mbber and NR-based systems, whereas PSAs based on SBR may require aromatic or aromatic modified aUphatic resins. 

The chemical nature of the tackifier also affects the compatibility of resin-elastomer blends. For polychloroprene (a polar elastomer) higher tack is obtained with a polar resin (PF blend in Fig. 27) than with a non-polar resin (PA blend in Fig. 27). Further, the adhesion of resin-elastomer blends also decreases by increasing the aromatic content of the resin [29]. Fig. 28 shows a decrease in T-peel strength of styrene-butadiene rubber/polychloroprene-hydrocarbon resin blends by increasing the MMAP cloud point. Because the higher the MMAP... 

Tackifiers. SBRs have poor tack, so addition of tackifiers is necessary. The tackifier increases the wetting of the adhesive and also increases the glass transition temperature of the adhesive. Typical tackifiers for SBR adhesives are rosins, aromatic hydrocarbon resins, alpha-pinene, coumarone-indene and phenolic resins. 

Tackifiers. The tackifiers usually are hydrocarbon resins (aliphatic C5, aromatic C9) or natural resins (polyterpenes, rosin and rosin derivates, tall oil rosin ester). They improve hot tack, wetting characteristics and open time and enhance adhesion. The content on tackifiers in a hot melt can be in the region of 10-25%. 

Certain resinous materials that act as plasticizers are well noted for increasing the tack of the formulation. Traditional tackifiers were based on naturally occurring resins such as pine tar. Today, tackifiers used in modem adhesive formulations include aliphatic and aromatic... 

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. 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. 

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