The forces of adhesion of acrylic adhesives
Acrylic adhesives come in the form of emulsions or solvent soluble form. These instant adhesives are generally used as pressure sensitive adhesives that are ideal for flooring, paper lamination, and textiles as well as a flocking adhesive. To flock means joining substrates to a layer of adhesive to ensure a quality flocked finish. There are reactive acrylic adhesives that differ from the standard acrylics because of their fast bonding time and the ability to bond to different types of substances. These acrylic adhesives include:
· Second generation acrylics – used for metal to metal or metal or plastic bonding. This type of adhesive are made of two components; Part A being rubber dissolved in acrylic monomers and Part B as the peroxide catalyst.
· Anaerobic instant adhesives – used for threadlocking applications. This single component type of instant adhesive remains stable even in the presence of oxygen and only cross-links in its absence.
· Cyanoacrylate – is another single component adhesive that polymerizes very quickly at room temperature and can be used when fast bonds are required.
Synthetic rubber adhesives and how they are improved
Numerous polymers have been developed in order to match and improve natural rubber. Since natural rubber has good tack properties but not very high strength, rubber adhesives are added to various resins and other compounding ingredients to achieve specific properties.
· Polychloroprene – mainly used for contact adhesives to bond to a wide variety of substances like wood, laminates, leather, etc.
· Styrene- butadiene – for pressure sensitive tapes, tile adhesives or floor adhesives
· Syyrene-diene styrene – for pressure sensitive tapes and hot melt adhesives
· Polyisobutylene – for electrical tapes and sealing tapes
· Acrylonitrile-butadiene – for leather, rubber and vinyl adhesives
· Polyurethane – often cross-linked with isocyanaate used in vinyl laminations
· Polysulfide – used mainly as sealants but also with epoxy resins for concrete adhesives
· Silicone – used as adhesive sealants for glass to glass and glass to metal bonds
Epoxy resins as hard and strong instant adhesives
Epoxy resins are generally used as all-purpose instant adhesives as binder for cements and mortars, for industrial coatings, for potting and encapsulating media and for solidifying sandy surfaces in oil drilling. The good thing with epoxy is its compatibility with all common reinforcing fibers that includes fiberglass, carbon fibers, aramid and basalt. Epoxies can also be fine-tuned to suit the desired applications and manufacturing processes. For example pultrusion and compression modifying epoxy resins can be heat activated whenever required by the application.