UV Curing of Adhesives

Uses Free radical initiator for UV curing of adhesives, coatings, inks Trade Names Containing Esacure KIP100F Esacure KT37... 

Radiation curing adhesives are generally applied as solvent-free liquids. High-solids EB and uv curing liquid adhesives have been formulated from a variety of resins and elastomers. They include epoxy acrylates, epoxies, other acrylates, polyesters, blends of acrylate monomers with elastomers, and other compositions. 

Hall [4] prepared crossliked polymers that were effective as adhesives by UV curing of the neutralization product of diallylamine with selected carboxylic acids, (IV). Additional UV curable diallyl amine adhesives, (V), were prepared by Milne [5]. 

Thioxanthone compounds, having an intense absorption band around 380 nm, have been industrially developed as initiators of polymerization in UV curing of heavily pigmented (TiOa) resins [3]. However, conventional thioxanthone photoinitiators show problems associated with their poor solubility producing migration which may result in loss of adhesion and, possibly, gloss. To overcome these problems, polymeric photoinitiators with pendant thioxanthone moieties have been... 

Many UV curing aerobic adhesives show the unique property of having structural properties regardless of the cure mechanism used, as shown below. A more detailed discussion of UV curing aerobic acrylics can be found in Sec. IV. 

The contributions of physics to adhesion are further manifested by the extension of uv- and electron-beam curing of adhesives to low temperatures. Radiation-curable adhesives were originally intended to eliminate solvents in the systems. However, the use of certain toxic acrylate monomers presented some problems. So far, radiation-curable systems have become technologically challenging, but economically less attractive than most thermally cured systems. Since one of the earliest papers on photoadhesives by Nakano (35) many patents have been issued on this subject. Two reviews have been published by Stueben (36). ... 

A fabricated plastic holder for an electronic pick-up head is assembled and the concentric parts are adjusted to a fine tolerance. An adhesive is applied across gaps that may vary to 1/8-in. wide and cured. A filled UV-curing aerobic adhesive has been chosen due to its rapid cure "on demand" and low shrinkage on cure, keeping the parts within the required alignment of six seconds of arc. 

Epoxy adhesives use a catalytic cure mechanism. The catalyst is a byproduct from the reaction of the photoinitiator to UV light. By definition, a catalyst is something that promotes a chemical reaction, but is not consumed in the reaction. One consequence of this is that UV-curing epoxy adhesives can exhibit a shadow curing capability— material that is not directly exposed to UV light will cure, sooner or later. 

Gurit has developed and launched the RENUVO blade-repair system (see Section 10.1.2) which overcomes the above disadvantages, Cripps (2011). Depending on the thickness of the composite laminate, a high intensity UV cure of 60-180 s cures the material to its full value. The RENUVO materials are specially formulated, and exhibit excellent handling, adhesion and cured properties at temperatures as low as +5°C and at high humidity... 

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