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Laminates: got it covered?
Q. What makes a laminate UV resistant?
A. A laminate is made UV resistant by the components added to the film and the adhesive system of the film. At Seal Graphics, we use two components: UV absorbers dispersed within the adhesive and UV inhibitors, which lie within the film.
Inhibitors prevent the film from breaking down under UV exposure but do nothing to affect the image itself. Their only purpose is to protect the film. PVC would otherwise discolour under UV exposure and will still do so if insufficient inhibitors are used. PET and OPP films do not contain UV inhibitors and will become brittle under UV exposure resulting in cracking and splitting over time.
Absorbers absorb light at a molecular level at the wavelengths of the UVA and UVB spectrum. This energy is soaked up by the adhesive, thus protecting the image surface.
Q. Are there any chemical or physical processes that run off when laminates are subjected to UV light?
A. As the absorption takes place at a molecular level, there are no chemicals created to run off.
Q. How does the adhesive react with inks?
A. As long as the ink/image is dry, there is no reaction. In most cases, an image can be laminated so long as it is touch dry.
Q. How do you test for UV resistance?
A. There are several methods that can be used to determine the level of protection that a laminate film provides. To achieve comprehensive results, all of the following need to be used in conjunction: UV spectrometer and UV black light in a laboratory setting, the use of QUV/Atlas weatherometer equipment and site testing, usually in Florida or Colorado to test for extreme sunlight conditions.
Q. What published guidelines are available?
A. There are no government guidelines. The standards Seal holds have been driven by industry needs and have evolved and improved over the years.
Q. How long are laminates durable in application?
A. This depends on the type of film and the geographical site of the finished product. At Seal Graphics, we provide a factor which should give an indication of how long a laminated image will last compared with an unprotected image. For example, if an unprotected image would only maintain its original appearance for one day in a south-facing location in the south of France, then a film with a factor of 100 would maintain the original image appearance for a period of 100 days.
Q. How important is UV resistance when developing new laminates?
A. UV resistance will always be important, but it depends on the application - whether the film is intended for indoor or outdoor use. If outdoors, what are the likely climatic conditions, the amount of rainfall and
humidity expected? What types of media will it be used with: water-based inkjet (UV or dye-sub inks), UV inkjet, solvent or photographic inks?
Q. Are there any laminates now available that are not UV resistant?
A. Yes but these are primarily for indoor use.
Q. Which Seal products best retard the fading process?
A. All our films offer UV resistance but, due to the adhesive formulation, the Print Shield Pro, Print Guard and UV Sol Lam ranges are the only films presently available that have been specifically developed to retard the fading process of the image.
