The tackifier is added to the modified asphalt to moisten the bonding surface through surface diffusion or internal diffusion, thereby improving the bonding strength between the modified asphalt and the adhered material.
Based on the difference in solubility in the two phases of ABA block polymer thermoplastic elastomer, commonly used tackifiers are divided into three categories. The solubility parameters of the first type are generally relatively low and are only compatible with non-polar rubber phases and petroleum asphalts. Family and alicyclic petroleum resins, rosin and hydrogenated rosin resins, and terpene resins all belong to this category. They can Reduce the elasticity, modulus and cohesive strength of self-adhesive modified asphalt, and give the self-adhesive modified asphalt initial adhesion and peel strength.
Tackifier properties
Tackifiers are divided into water-based and oil-based ones. Water-based ones include water-based thickening emulsion, water-based thickening resin, and water-based thickening powder; oil-based ones include water-based thickening emulsion, water-based thickening resin, and water-based thickening powder. Tackifying rosin resin, modified rosin resin.
As an adhesive, the tackifier is mainly used to improve the initial adhesion and holding force of the product; when used in coatings, it is mainly used to increase the adhesion to the substrate!
Concept
Despite the viscosity of natural rubber, the adhesive bond strength produced by rubber alone is insufficient for many applications. Most commercial synthetic elastomers lack stickiness, either to themselves or to other surfaces. Therefore, in order to increase their viscosity, resin tackifiers are added. A large number of latex and solvent systems, especially when used as contact glues, use specific types of tackifying resins.
Function
Common tackifiers have a relative molecular mass of 200 to 1500 and generally have a large and rigid structure. They are thermoplastic and usually amorphous vitreous at room temperature. They have a broad softening point, ranging from liquids at room temperature to brittle hard solids with melting points as high as 90°C. They are generally quite soluble in hydrocarbons, aromatic hydrocarbons and many typical organic solvents. For relevant U.S. patent documents from 1976 to 2001, please refer to the corresponding survey table at the end of this chapter. The selected tackifying resin affects the quality of the adhesive from the standpoint of viscosity, tensile strength, color retention and resistance to oxidative embrittlement. Unmodified gum and wood rosin can be converted into esters, which have a certain viscosity at first, but have poor aging resistance after the glue is applied. Rosin esters stabilized by hydrogenation or polymerization are resistant to oxygen attack and have the best overall properties when used in adhesives. Examples are Staybelite Ester 10 or Fora 185 (glyceryl ester of hydrogenated rosin), Pentalyn H or Fora1 ??105 (pentaerythritol ester of hydrogenated rosin).
Lower softening point resin
The tackifying limit effect of lower softening point resin is greater, but this effect can only be obtained at high concentrations. The tensile strength will decrease with the increase of tackifier concentration, and the reduction rate of different tackifiers is also different.
Styrene-butadiene rubber system
The styrene-butadiene rubber system itself has poor viscosity. When a sufficient amount of Penta1yn H tackifier is added, the viscosity is generated, and a second appearance appears in the film. Mutually. When the tackifier concentration is 60% to 65%, the viscosity reaches the maximum. However, for several different types of crystal-resistant soft neoprene, the relationship between the softening point and viscosity of the above-mentioned tackifier does not necessarily hold true. Like natural rubber, high-viscosity synthetic rubber films will lose their viscosity and two-phase characteristics when continuously heated at 93°C.