UV Adhesives for Plastic Bonding
Adhesives or cementing agents can take varied forms such as metal bonding adhesive, plastic bonding adhesive, panel bonding adhesive etc. All top stores and distributors stock all varieties needed for varied applications. Plastic bonding adhesives include Epoxy glue or the Cyanoacrylate adhesive. UV curable adhesives are another bonding mechanism that is used for plastic bonding.
What are UV Curable Adhesives?
UV curing adhesives are as the name suggests adhesives that require ultraviolet light or another source of radiation for initiating the curing process. In this form of adhesive, a permanent bond is developed without the need for heating as required in Thermoset adhesives. These adhesives harden or solidify on exposure to the ultraviolet radiation source that has a well-defined wavelength and intensity. It has to be borne in mind that UV curable adhesives are not a type of adhesive; it only indicates the mechanism of curing. For example, an epoxy adhesive can be a two-component epoxy or a heat cure epoxy or a UV cure epoxy. UV curing technology is also available in adhesives like UV Cyanoacrylate, UV Acrylic, UV Anaerobic and UV Silicone.
How Does the Bonding Mechanism Work?
The photoinitiator molecules contained in the UV cure adhesives are stimulated or/and decomposed on absorbing the energy radiated by the ultraviolet light. This leads to the production of free radicals which begin and hasten the adhesive’s curing process achieving solidification in a very less time. The energy content in ultraviolet light with a longer wavelength is much lower than that in ultraviolet light with a shorter wavelength. The photoinitiator contained in the adhesive will determine the correct wavelength to be used. The rate of curing is determined by the intensity of ultraviolet light emitted, it’s distance from the adhesive, its application time, adhesive thickness and permeability of the substrate through which the ultraviolet light passes. The substrate’s permeability has to be taken into account if the bonding has to occur through UV adhesives.
When did UV Curable Adhesives Find Use in Industrial Grade Plastics?
On introduction of Visible light cure abilities; the UV curable adhesives became useful in industrial grade plastics. Industrial grade plastics contained UV blocking agents for preventing them from getting yellowish over a period of use. The UV blocking agent is not visible to naked eye and hence the plastic looks clear and clean; however, the agent obstructed the passing of UV light which is so necessary for the functioning of the UV curable adhesives. Adding Visible light initiators to UV curable adhesives ensured the passing of UV light through the plastic and enabling their use in the industry.
These adhesives which contain Visible light and UV should be aptly called light curable adhesives; however, they are referred to as UV adhesives by almost every manufacturer.
These adhesives cost competitive in comparison to other adhesive mechanisms. Equipment costs depend upon the scale of the project and sunshine is freely available. These are popularly used in various applications and this is proof enough that the energy and times savings obtained through them are more than the other cure methods.
UV adhesives have the ability to cure rapidly leading to considerable energy savings and gains in productivity. It is no wonder, therefore that they are popularly used for plastic bonding.
Vigil Miranda is a foremost supplier of engineering adhesives and loves to impart information on the same through his articles. In this article, he gives details on UV adhesives and its role as a plastic bonding adhesive.
