Light-curing adhesives

UV and EB formulations consist primarily of oligomers, monomers, photoinitiators (in the case of uv or light cured adhesives) and crosslinking agents or accelerators (in the case of EB cured adhesives), and the other additives that would normally be expected in adhesive formulations. However, the effect of these additives on storage and processing conditions must be determined as well as the effect on cohesive and adhesive properties. Close attention needs to be paid to the photosensitive nature of these additives and to the conditions under which they are stored and used. 

Radiation-source In bonding technology, equipment for the curing of UV-electron beam and light-curing adhesives. 

Technical Data Sheets for LC 1100 and 1200 Series Light Curing Adhesives, 3M Co. (undated). 

Salemi, CM. and Serenson, J. A., Light-cure adhesives for needle assembly, (pp. 32-40), RadTech Report, March 2003. 

UV light-cured adhesive systems are cheaper than EB-cured systems. 

Nearly 42% of the demand for all adhesives comes from the packaging sector. Radiation-curable adhesives are used primarily for packaging, with paper and paperboard the dominant materials used in the packaging. Radiation-curable adhesives can be used on glass, metal and some plastic materials. Other applications for radiation-curable adhesives are in healthcare, electronics, communications, pressure-sensitive tape and consumer applications. Ultraviolet (UV)-curable adhesives are best suited to small-scale applications, while electron beam (EB)-curable adhesives are more appropriate in high-volume applications (an EB system has a higher installation cost). One additional characteristic of EB-curable adhesives is that they can cure the area between two substrates. UV light-cured adhesives can also be applied on heat-sensitive substrates and are not affected by ambient temperature or humidity. 

The wide use of polycarbonate and flexible PVC in the medical industry resulted in the development of a range of adhesives which were not only considerably more flexible but also cured at the visible end of the UV spectrum (UW) 390-470 nm, thus overcoming the problem of absorbance at shorter wavelengths. Whilst these products are described as visible light curing adhesives, it should be noted that an investment in UV equipment is still required for rapid curing. 

Salemi CM, Serenson JA. Light-Cure Adhesives for Needle Assembly. RadTech Report, March 2003 32-40. 

Light-cure adhesives offer a few advantages, including fast cure time and low energy use. The major benefit of UV curing is that it is a cure-on-demand process. The adhesive will not cure until the UV light is shone on it, and, when that occurs, it takes only seconds to form a complete bond. The process is fast, solvent free, and economical [19]. 

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