Adhesion promoters reversible

The mechanism of chemical adhesion is probably best studied and demonstrated by the use of silanes as adhesion promoters. However, it must be emphasized that the formation of chemical bonds may not be the sole mechanism leading to adhesion. Details of the chemical bonding theory along with other more complex theories that particularly apply to silanes have been reviewed [48,63]. These are the Deformable Layer Hypothesis where the interfacial region allows stress relaxation to occur, the Restrained Layer Hypothesis in which an interphase of intermediate modulus is required for stress transfer, the Reversible Hydrolytic Bonding mechanism which combines the chemical bonding concept with stress relaxation through reversible hydrolysis and condensation reactions. 

Both primers and adhesion promoters are strongly adsorbed onto the surface of the substrate. The adsorption may be so strong that instead of merely being physical adsorption, it has the nature of a chemical bond. Such adsorption is referred to as chemisorption to distinguish it from reversible physical adsorption. 

Uses Tackifier, binder, plasticizer for inks, textile sizes and finishes, latex modification, paints, adhesives adhesion promoter (acrylic pressure-sensitive adhesives) laminating heat sensitizer for rubber latex pigment binder in textile finishing protective colloid in emulsions flexibilizer, vise, control agent for photoresist coatings semiperme-able membranes (reverse osmosis plants) antistat, binder, film-former in cosmetics finish component for poly (phenyleneterephthalamide) food-pkg. resins in food-contact PU resins Regulatory FDA 21 CFR 175.105,177.1632,177.1680 Manuf/Distrib. Aldrich BASF ISP... 

Another foil type offered by laminate supphers, reverse-treated foil (RTF), offers an advantage for producing fine lines. The RTF copper has adhesion promoter applied to both sides and is classified by 4562 as code R (reverse-treated bond enhancement [cathode side] stain-proofing on both sides).This approach provides advantages to imaging fine lines. When the copper tooth is reversed, the fabricator can improve fine definition by allowing the etch chemistry process to stop at the surface of the laminate. 

A two-stage process of a permanently soluble primer with a cross-linking adhesive may ensure reversibility for the process (Podany et al 2001). The use of adhesion promoters such as coupling agents should be considered only in extreme conditions of use, e.g. on externally exposed glass, as the chemical bonds with the adherend can be broken only by dissolving away a bit of its surface. 

These pumps are widely used for dispensing a wide variety of chemical and food media. They have been used for applying adhesives since the start of the third century AD. The design and operation are explained in O Fig. 38.6. The advantage of these pumps is that they can be operated without valves. Defined partial volumes form between the rotor and stator, and these are transported along the axis of the rotor by rotation. At the end of the adhesive application, a short reversal of the rotor promotes breaking of the adhesive thread. These pumps are driven by electric motors. When operating these pumps, special attention must be paid to a number of points ... 

---