Ultraviolet cured adhesives

Impruv, Ultraviolet curing adhesive, Loctite Corp., North American Group... 

If the outer (female) substrate had been transparent in Figure 5.12, it may have been possible to use an ultraviolet-curing adhesive. The benefit of UV adhesives is that the product will only cure on demand and so there will be plenty of time to rotate the component parts to ensure full joint coverage. Where the assembly process is horizontal, the chamfer is not always necessary but the male part may require to be rotated to ensure full joint coverage. 

Adhesion Loss of Ultraviolet-Cured Lacquer on Nickel-Plated Steel Sheets... 

Well over 100,000 high intensity ultraviolet curing units are in industrial use. Their main applications are surface curing of inks, coatings and adhesives. They typically operate in the 200 150 nm wavelength range, with lamp electrical power input as high as 240 W/cm (600 W/in.).1... 

The main sources of energy for curing epoxy adhesives by radiation are electron beam (EB) and ultraviolet light (uv). Both provide instantaneous curing of resins that polymerize from a liquid to a solid when irradiated. The uv systems account for approximately 85 percent of the market for radiant cured adhesives, EB systems account for about 10 percent, and the remainder are chiefly adhesives that can cure by exposure to both visible and infrared light. 

Current practice in the ultraviolet curing of paints, adhesives, and inks relies heavily on the use of photoinitiators of this type. An alternative procedure involves the use of photosensitizers which undergo excitation at an irradiation frequency which is not effective on the monomer or initiator of direct interest. Transfer of energy from the excited photosensitizer takes place at a frequency at which the recipient molecule can absorb and subsequently decompose. Benzophenone is a common photosensitizer in radical reactions. 

Sealants durability resistance to heat cold water, ozone and ultraviolet radiation adhesion to a variety of substrates high recovery colour stability glazing sealants construction sealants (neutral cure systems) sanitary sealants... 

Cyanoacrylates are not appropriate for the bonding of the steel parts of an automobile, because of the environments that the car will be exposed to. Those environments include such things as rain, variations in temperatnre, exposure to solvents (such as gasoline, oil, and windshield washer solntion), ozone, acid rain, salt spray, and ultraviolet light from the Sun. (A more appropriate adhesive for car parts would be an epoxy-based adhesive.) Another example of a special adhesive would be the one used to attach a new rearview mirror in an antomobile. Because the cured adhesive in this case will be exposed to wide variations in temperature and to an extremely large amonnt of nltraviolet fight from the Snn for prolonged periods of time, an adhesive formnlated specifically for these conditions should be used. 

The UV technology alluded to above holds out the promise of even more superior labels. In this process, ultraviolet cured inks are used as the printing medium. These are cured by exposure to industrial type UV mercury vapor lamps in either a non-inert system (air environment) or in an inert (oxygen-free) system. The result is excellent adhesion to vinyls, polyesters, polycarbonates, butyrates and acetates and a cured elongation of between 20 and 40% to avoid embrittlement of the substrate. Initial testing has exhibited little sign of degradation and excellent chemical resistance after three years of exterior exposure. Such UV labels as well as other techniques should be considered whenever use demands extended label performance. 

One of the newer developments in adhesives is the growing use of ultraviolet light or electron beam radiation to cure adhesives. Adhesives designed for UV- or E-beam curing are usually pressure sensitive or hot-melt systems based on acrylates, functional rubbers, or epoxidized rubbers, and use special UV or EB lamps to provide the cure. These systems can provide greatiy improved heat resistance compared to hot melts, and avoid the soivent emission problems of some of the solvent-based systems with which they compete. 

Schick S. Portable ultraviolet system provides high intensity cures. Adhesives Age. Apr. 1986. 

Aerobic acryhc ultraviolet (UV) and activator curing adhesives were developed with the idea of meeting the requirements of maintaining or increasing product and environmental quahty while delivering the ultimate in process efficiency. 

K. C. Stueben, "Ultraviolet Cured Pressure Sensitive Adhesives," in Ref. 14. 

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