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Evaluating Tackiness of Polymer-Containing Lubricants by Open-Siphon Method
Published in Leslie R. Rudnick, Lubricant Additives, 2017
Brian M. Lipowski, Daniel M. Vargo
A tackifier is a lubricant additive that imparts a tack or stringiness to a substance and is typically used to provide adherence in fluid lubricants and stringiness in greases. Tackifiers are used to inhibit dripping, removal, and flinging of lubricating oils and to impart texture in greases. In lubricant applications, most tackifiers are dissolved polymers in either mineral oil or vegetable oil–based diluents. The polymers are often polyisobutylene (PIB) with a molecular weight of 1000–4000 kDa or rarely an ethylene–propylene copolymer (OCP) with a molecular weight of approximately 200 kDa. The tackiness of a solution generally increases with polymer molecular weight. The operational environment of the lubricant dictates polymer selection; for example, in high mechanical shear and high temperature applications, OCPs are generally preferred over PIBs. The base oils may be paraffinic, naphthenic, or vegetable, depending upon application. Lubricant dripping, splashing, and aerosol formation (misting) are major problems for many lubricants. Tackifier additives in lubricating oils are useful in minimizing these problems. Application areas where lubricant retention and enhanced film thickness is benefited by tackifiers are open gear oils, slideway lubricants, wire ropes, textile operations, chain saws, chains, and rock drill oils. Tackifier additives in greases enhance the greases ability to stay in place and to resist removal by water in operation. Specialty applications include food grade, aerospace, and biobased lubricants.
Role and Methods of Formulation
Published in István Benedek, Mikhail M. Feldstein, Technology of Pressure-Sensitive Adhesives and Products, 2008
The formulator must clarify the scope of tackification with resins, the parameters influencing tackification, and the effect of tackification on other (nonadhesive) performance characteristics of the PSA. In Ref. [14], the scope of tackification with resins, the theoretical basis of the tackification with resins (global and partial tackification), the criteria for the choice of tackifier resin (e.g., compatibility, polarity, aliphatic/aromatic ratio, molecular weight and MWD, softening point, and chemical composition) were discussed in detail. The main grades of tackifier resins and their characteristics (e.g., molecular weight, Mw/Mn, chemical composition, polarity, and color) are discussed in detail in Ref. [15], where resin dispersions, their formulation, manufacture, and stability are also described. The main tackifier resin classes (e.g., rosin derivatives, hydrocarbon resins, coumarone–indene resins, polyterpenes, terpene-phenolic resins, ketone resins, reactive resins, and hybrid resins) are discussed in detail. An economic comparison of tackifier resins is also given.
Phenolic Adhesives and Modifiers
Published in Gerald L. Schneberger, Adhesives in Manufacturing, 2018
Robert H. Young, J. M. Tancrede
The bonding range of neoprene contact adhesives is most readily varied by the grade of neoprene and the type and level of phenolic resin used. The fast-crystallizing grades of neoprene rubbers, such as Neoprene AC, AD, and AF*, have poor tack retention. Addition of slower-crystallizing grades of neoprene rubber and tackifiers in particular will enhance tack. Tackifiers decrease in efficiency in the order of terpene, terpene-phenolic and heat-reactive alkyl phenolics. The complexation of alkyl phenolics with metal oxides further decreases adhesive tack, presumably because of more rapid solvent release. However, this type of tackifier greatly enhances adhesive heat resistance and metal adhesion.
The effect of Magnesium resinate complex on the peel strength of polychloroprene-based rubber adhesive
Published in The Journal of Adhesion, 2023
Bita Faridi, Iraj Amiri Amraei, Hassan Fattahi, Mahmoud Razavizadeh
The reaction of p-tert-butyl phenol resin with MgO in solution results an infusible magnesium resinate complex that will confer the property of heat resistancy to the adhesive. This reaction is carried out in an organic solvent and will proceed in situ in the adhesive formulation within a few days.[8,12] For this reaction, maintaining a certain temperature range (25 ~30 °C) and reaction time (5 ~15 h) are important for the adhesive quality.[13] The unique ability of phenolic resins to form multiple hydrogen bonds results in improved performance when compared to the other types of resins used for this application. One effect of this improved performance is that less tackifier resin is required to achieve the desired tack level.[1]
Viscoelastic behavior of pressure-sensitive adhesive based on block copolymer and kraft lignin
Published in The Journal of Adhesion, 2023
Rogerio R. de Sousa Júnior, Guilherme E.S. Garcia, Demetrio J. dos Santos, Danilo J. Carastan
To meet the requirements for a PSA, different components are usually combined to provide complementary functions. The base polymer must be an elastomer, such as natural rubber, silicone, acrylics, or styrenic block copolymers.[2,7] The most common styrenic copolymers used in PSA formulations are triblock copolymers, composed of hard polystyrene (PS) end-blocks and a rubbery middle-block, usually made up of isoprene, butadiene, or ethylene-butylene. In this way, one block segment acts as a soft domain, contributing to adhesive flexibility and facilitating its contact with the adherend when subjected to external loading. The coexisting hard block segments gather in domains that behave as physical crosslinking sites, avoiding adhesive flow and its early failure.[7] The final composition of a block copolymer-based PSA particularly involves the use of low molecular weight resins or liquids to obtain adequate viscoelastic and adhesive properties for the application.[8,9] A necessary component is the tackifier resin, which provides tackiness and improves the wettability of the adhesive.[7,10] The tackifier is more effective if it has preferential interaction with the soft midblock.[7] Sung et al[11] evaluated different concentrations of aliphatic, dicyclopentadiene and aromatic hydrocarbon resins as tackifiers of a polystyrene-b-polybutadiene-b-polystyrene (SBS) block copolymer. They found that the aliphatic and dicyclopentadiene resins have good interaction with the flexible block and, consequently, reduce the rubber-like plateau modulus, while the aromatic resin, which interacts with the rigid PS segments, increases the rubber-like plateau modulus and compromises adhesion.
Progress on rubber-based pressure-sensitive adhesives
Published in The Journal of Adhesion, 2018
Tackifier is the necessary ingredient of rubber-based PSAs because it leads to tack. For block copolymer-based PSAs, the effect of tackifier on adhesive performance is dependent on the compatibility of tackifier with copolymer at large extent. In the last 20 years, the researchers obtained many valuable findings in the compatibility field of styrene-block copolymer-based PSAs [44–48, 61–65]; the key points include: (1) phase status of SIS and tackifier resin varied with the temperature [61]; (2) the optimum combination between rubber block copolymers and resin tackifiers can obtain good component compatibility. For SBS polymer HMPSA, the aliphatic-aromatic copolymer is the best resin. For HMPSA derived from the mixture of SIS and SBS, they susgested the use of single resin instead of resin blends as tackifier. For SIS polymer HMPSA, the mixture of aliphatic and aromatic resin is the best resin [62]. (3) the tackifiers that have good compatibility with polyisoprene or polybutadiene phase and weak compatibility with polystyrene phase can effectively reduce the plateau modulus G’ of PSAs and increase largely the wetting property and tack of PSAs, but did not reduce the shear strength of PSAs. The hydrogenated resin is a good case, and the PSAs have maximum probe tack at 50–60% hydrogenated resin content [48]. (4) The tackifiers that have weak compatibility with polyisoprene or polybutadiene phase and good compatibility with polystyrene phase cannot improve tack of PSAs, but can reduce the shear strength of PSAs. The phenol formaldehyde resin is a good case [44]. (5) The compatibility of rosin or resin with polyisoprene, polybutadiene, or polystyrene phase is varied with hydrogenated degree. Kim and his co-workers [45] did much work on this direction. At lower hydrogenated degree, C9 resin has good compatibility with polystyrene, which results in the small tack of adhesive. With the increase in hydrogenated degree of C9 resin, the compatibility between components was enhanced obviously. For SBS-based PSA, the formulation has the best compatibility and maximum tack when the hydrogenated degree is 0.7; for SIS-based PSA, the formulation has the best compatibility and maximum tack when the hydrogenated degree is 0.951. (6) The compatibility between components also affects the bulk and surface viscoelasticity of PSAs [47].