Solvent-activated adhesives

This method is a postponed wet-assembly process and is usually unsuitable for non-porous adherends. It is applicable to adhesives that can be reactivated by solvents unlike most two-part adhesives. Solvent activation... 

Adhesive, solvent-activated— A dry adhesive or adherend that is rendered tacky just prior to use by apphcation of a solvent. 

Tetrahydrofurfuryl alcohol is used in elastomer production. As a solvent for the polymerization initiator, it finds appHcation in the manufacture of chlorohydrin mbber. Additionally, tetrahydrofurfuryl alcohol is used as a catalyst solvent-activator and reactive diluent in epoxy formulations for a variety of apphcations. Where exceptional moisture resistance is needed, as for outdoor appHcations, furfuryl alcohol is used jointly with tetrahydrofurfuryl alcohol in epoxy adhesive formulations. 

Progress has also been made in lamination techniques in recent years. The current state of the art is represented by solvent-free hot melt adhesives applied directly to the back of the decor elements. The hot melt adhesives are activated by... 

Film adhesives may be used only on flat surfaces or simple curves. Application requires a relatively high degree of cure to ensure non-wrinkfing and removal of separator sheets. Characteristics of available film adhesives vary widely, depending on the type of adhesives used. Film adhesives are supplied in both unsupported and supported types. The carrier for supported films is generally fibrous fabric or mat. Film adhesives are supplied in heat-activated, pressure-sensitive, or solvent-activated forms. 

Solvent-activated forms are tackified and rendered pressure-sensitive by wiping with solvent. This type of adhesive is not as strong as other types, but is well suited for contoured, curved, or irregularly shaped parts. Manual solvent-activation methods should be closely monitored so that excessive solvent is not used. Chemical formations available in solvent-activated forms include neoprene, nitrile, and butyral phenolics. Decorative trim and nameplates are usually fastened onto a product with solvent-activated adhesives. ... 

Tape and film adhesives are poor gap fillers but offer a uniformly thick bond line, no need for metering, and easy dispensing. Adhesive films are available as a pure sheet of adhesive or with cloth or paper reinforcement. Another form of adhesive is powder or granules that must be heated or solvent-activated to be made liquid and applicable. 

Such adhesives can be applied to adherend surfaces from ketone solution and after drying may be heat- or solvent-activated at 50-70°C. They are especially popular for vinyl and wood bonding. In this, solvent mixtures of a urethane elastomer prepolymer are mixed with a solution of the diisocyanate. This reactive mixture is applied to a substrate where it dries... 

Adhesives may also be classified by the way they are applied or cured. Hence, anaerobic adhesives are adhesives that set only in the absence of air, for instance, when confined between plates or sheets. A contact adhesive is one that is apparently dry to the touch but will adhere to itself instantaneously on contact (also called contact bond adhesive and dry bond adhesive). A heat-activated adhesive is a dry adhesive film that is made tacky or fluid by application of heat or heat and pressure to the assembly. A pressure-sensitive adhesive is a viscoelastic material that in solvent-free form remains permanently tacky. Such materials will adhere instantaneously to most solid surfaces with the application of very slight pressure. Room-temperature setting adhesives are those that set in the temperature range of 20-30°C. These are usually two-component adhesives that must be mixed before application. A solvent adhesive is an adhesive that has a volatile organic liquid as a vehicle and sets or becomes tacky after the solvent has evaporated. A solvent-activated adhesive is a dry adhesive film that is rendered tacky just before use by applicafion of a solvent. 

Pressure-sensitive adhesives were so named because they bond under very light pressure. However, since we name other adhesives based on what accomplishes their change in state (heat-activated, solvent-activated adhesives, etc.), perhaps it would be more descriptive to refer to these materials as time-scale sensitive adhesives. 

Ex. 4. Royal M6482 and S-5210 adhesives can be applied to adherend surfaces from ketone solution and after drying may be heat or solvent activated. M6482 activates at 180— 240 F and is a good adhesive for vinyl and for wood. S-5210 activates at 135—155°F and was designed for bonding man-made shoe upper stocks, leather, vinyl, etc. ... 

Abstract In this chapter, classification of adhesive and sealant materials is presented. For this purpose, various categories are considered depending on the polymer base (i.e., natural or synthetic), functionality in the polymer backbone (i.e., thermoplastic or thermoset), physical forms (i.e., one or multiple components, films), chemical families (i.e., epoxy, silicon), functional types (i.e., structural, hot melt, pressure sensitive, water-base, ultraviolet/ electron beam cured, conductive, etc.), and methods of application. The classification covers high-temperature adhesives, sealants, conductive adhesives, nanocomposite adhesives, primers, solvent-activated adhesives, water-activated adhesives, and hybrid adhesives. 

Solvent-activated These types of adhesives become tacky when wetted with an organic solvent. 

In solid form, thermoplastic adhesives are available as unsupported or supported films, granules, and in lengths of extruded, flexible, cordlike materials. The fluid form is obtained for bonding by either solvent or heat activation. Heat activation requires substrates which can withstand the required temperatures. If the resin compound also contains a thermosetting resin, heat application is continued to cross-link it. Solvent activation, on the other hand, requires substrates to permit the release of the solvent by diffusion if the bonding area is large. 

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