Coumarone-indene tackifiers

Uses. Coumarone-indene resins have outlets in paints, as tackifiers in mbber compounding, and as adhesives in the manufacturing of flooring tiles (see Hydrocarbon resins). 

Natural rubber displays the phenomenon known as natural tack. When two clean surfaces of masticated rubber (rubber whose molecular weight has been reduced by mechanical shearing) are brought into contact the two surfaces become strongly attached to each other. This is a consequence of interpenetration of molecular ends followed by crystallisation. Amorphous rubbers such as SBR do not exhibit such tack and it is necessary to add tackifiers such as rosin derivatives and polyterpenes. Several other miscellaneous materials such as factice, pine tar, coumarone-indene resins (see Chapter 17) and bitumens (see Chapter 30) are also used as processing aids. 

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. 

In this section the rosins and rosin derivative resins, coumarone-indene and hydrocarbon resins, polyterpene resins and phenolic resins will be considered. The manufacture and structural characteristics of natural and synthetic resins will be first considered. In a second part of this section, the characterization and main properties of the resins will be described. Finally, the tackifier function of resins in rubbers will be considered. 

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. Phenolic resins are added to increase strength, oils resistance and resiliency of NBR adhesives. On the other hand, tack and adhesive properties can be improved by adding chlorinated alkyl carbonates. To impart tack, hydrogenated rosin resins and coumarone-indene resins can be added. 

Tackifying and adhesion-promoting resins (e.g., hydrocarbon, rosin esters, coumarone-indene, terpene resins)... 

Tackifiers. Pine tar, coumarone-indene resins, zylol-formaldehyde, and other resins are used to increase the tack of rubber compounds. Tack, here, means stickiness of the un-cmed rubber stock to itself, rather than to other things, such as metal surfaces. Tack has also been called autoadhesion. It is extremely important for building up structures such as tires. Natural rubber inherently has good natural tack, but most synthetic rubbers do not. 

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. 

Tackifiers. Although SBRs can be produced with tack, the physical properties of such polymers usually do not fully satisfy the application requirements. For this reason tackifying resins are normally incorporated into adhesives based on SBRs. These resins improve the kinetics of wetting and increase the overall Tg of the adhesive composition. Typical tackifiers for SBR are rosin-based materials, aromatic-containing petroleum hydrocarbon resins, alpha-pinene, coumarone-indene, and some phenolic resins. 

Tackifiers with aromatic content, particularly a-methyl styrene and vinyl toluene copolymers and coumarone-indene resins, are of significant industrial value. 

Tackifiers - Elastomers with little or no natural tack can be improved by the addition of resins or resin oils (natural abietie aeid derivatives), polyindene (coumarone-indene) resins, polyterpene resins and phenol-formaldehyde resins. 

A tackifier is a component to provide initial tackiness to adhesives. The compatibility of the tackifier to the main components is very important to increase the tackiness without degradation of the adhesive mixture. For that purpose, natural resins such as rosin and dammar, modified rosins such as coumarone-indene resin, polymerized rosin, hydrogenated rosin and rosin ester, and polyterpene resin are used. Recently, alkylphenol resins, terpene phenol resins, and xylene resins are out of use because of their hazardous nature inducing sick building syndrome. 

Building tack in nitrile compounds may be achieved by the incorporation of tackifying resins such as coumarone indene (e.g., Cumar MH) or nonactivated phenolic types such as Schaiectady SP 1066 or hydrocarbon types such as Wingtack 95. It is important to use a minimum amount or no stearic acid, or replace it with lauric acid, and nonblooming, vay compatible plasticizers such as liquid NBR, phosphate esters, and glycol ether estos. 

Tackifiers may be required for building plies of HNBR compounds to other HNBR compounds or to other polymer formulations for composite constructions. Coumarone-Indene resins, Phenol-acetylene resins, Aromatic hydrocarbon resins, and Styrene-vinyl toluene resins work well at levels of up to 15 phr to tackify the resulting HNBR compound. 

Indene/coumarone resins find extensive application, especially in the production of adhesives, as reinforcers and tackifiers in the production of commerical rubber products, and in paint manufacture. Production of indene-derived resins in Western Europe is around 110,000 tpa. 

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. 

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