UV adhesives are an advanced group of products that bind under the influence of UV light and do not contain any solvents. Construction adhesivesare single-component products that are hardened with uv rays as well as visible light. Proper polymerization of adhesives is of great importance, in order to do it properly, the appropriate UV light intensity should be selected. The curing time of the adhesives depends on the irradiation parameters such as the type and power of radiation and the wavelength of the uv light.
The fast action of uv adhesives has an important effect in many manufacturing sectors. The range of adhesives develops widely under the influence of white light or UV light. It is a very useful function in every job, in industrial production, production of advertisements and signs. Uv adhesives are used for gluing plastics, but their main purposeis glass repair and the production of transparent plastic elements.
What are uv adhesives and how do they work?
UV adhesives, as already mentioned, are one-component products that differ in terms of viscosity. When the adhesive is exposed to UV rays, the liquid acrylic adhesive hardens and sticks to the adjacent surface. This technology enables the manipulation of plastics in any way, and gives the possibility of quick bonding when we need it. The big advantage of uv glue is its transparent consistency, which is ideal for gluing glass, while maintaining an aesthetic appearance. In a situation where we need to glue thicker glass or glass with decorated slants, a more flexible glue with less strength and greater viscosity will work. This is a safer solution as it eliminates stress and avoids cracks as the ambient temperature changes.
UV adhesives under the influence of UV rays consist of polymers and monomers containing similar vinyl groups, which are properties of acrylates. A photo initiator is added to this, it is stable until it is exposed to uv rays of a certain frequency. In the next stage of operation, the photo-initiator decomposes and reacts with acrylates to form a thermoplastic material.
Types of uv adhesives
Methacrylate adhesive are structural adhesives developed for high-strength joints. It has a multifunctional effect, but it should only be used in the joint between two materials, at least one of which must transmit uv rays. It replaces many mechanical methods of joining various materials. In the glue based on methacrylate, uv radiation causes the cleavage of photo initiators. The free radicals formed in this way initiate the polymerization of the adhesive.
Theepoxy glue here polymerization is triggered by photo initiators under the influence of uv rays. They produce cations that are involved in the formation of the epoxy polymer chains. Even in an open joint (in contact with oxygen), the adhesive hardens and forms a dry surface. Thanks to these functions, it can be used for potting welds in electrical circuits or optics.
How should you glue the glass properly?
It should be remembered that before using the glue, the glass surface must be thoroughly cleaned, degreased and dried to obtain the desired effect. Cleaning agents that do not contain surfactants should be used. It is recommended to use cleaning agents appropriately selected for the glass. When choosing a glue for glass, pay attention to the type of glued material. We will choose a different type of glue when gluing the glass elements themselves, and a different type of glue should be used when gluing glass to metal elements. In order to guarantee high durability, it is necessary to heat the elements before gluing them. This allows the residual moisture to completely evaporate and thus facilitates gluing. During gluing, all parts of the glass should be heated with a dryer or a heat gun to a temperature higher than 30 degrees. It must be borne in mind that when gluing construction elements, they must be properly secured against shifting.
It should be remembered that the final strength of the joint depends on the choice of low-viscosity or high-viscosity glue, as well as the type of glass used. All factors must be properly matched to the glued material. When choosing the right glue, remember that when joining glass with metal for joints exposed to dynamic loads, use a medium-viscosity glue. When we combine glass with glass, pay attention to the structure of the joined elements. There are two types of closed and open structures:
Aclosed structure is a structure that is designed to connect elements on a free surface. It is free from irregularities and airspace. In this case, elastic glue is used. It is a thick glue that has a high viscosity. After the hardening is complete, it remains permanently elastic.
The open structureis an irregularly shaped joint. The shrinkage of such a weld is so great that it can damage the surface of the joined elements. For joining open structures, adhesives with low viscosity should be used.
There are three ways of uv curing:
- Through-curing – to achieve the maximum curing effect, UV systems that emit light of high intensity and wavelengths ranging from 300 to 400 nm, i.e. long-wave UVA light, are indicated.
- Surface hardening – this is the most important work process during curing when gluing or pouring uv materials. However, if the wrong types of uv lamps are used, the surface remains sticky. To prevent this from happening, the uv radiation source should emit waves having a high intensity, in the wavelength range it should be less than 280 nm (uvc light). This type of hardening is very effective in avoiding an undesirable reaction. It can appear during contact with atmospheric air during the glued surface, which blocks the product hardening.
- Curing by means of secondary mechanisms – the effectiveness of this method of curing a lot depends on the wavelength and the intensity of the light that is on the surface to be glued. When choosing the most appropriate glue, it is greatly influenced by the UV transmittance of the various materials.
What are the advantages of hardening glass with uv glue?
- they are single-component adhesives, which makes them easy to dose in automatic application systems
- when properly cured, they are very durable
- very short setting time, the adhesive dries quickly and its action is immediate
- resistant to the impacting environment
- have a high ability to fill gaps
- have high resistance to water and other chemicals
- they are transparent, thanks to which they maintain an aesthetic appearance