Polycarbonate sheets are a perfect material for construction. They are lightweight, durable, aesthetic and easy to install.
However, polycarbonate disadvantage is its sensitivity to ultraviolet radiation from sunlight.
One of the properties of the polymer is its ability to absorb ultraviolet radiation. However, under its influence, polycarbonate degrades and is rapidly destroyed; it leads to yellowing, blushing and reduction in the strength of the material.
During the material production and study, technology of polycarbonate sheet protection against UV was changed. In the early years, to protect the polycarbonate from solar radiation a lacquer was applied. The disadvantages of this coating were cracking, blushing and uneven distribution over the surface of the sheet. Later, application of special protective coating by coextrusion was developed.
Protective coextrusion layer, which is an integral part of the sheet, is a polycarbonate, enriched with a special active additive. The greater is the concentration of the additive, the more effective and thinner can be coextrusion layer.
Therefore, the question about the coextrusion layer thickness of UV-protection, without reference to concentration of active additive in polycarbonate, is not correct. This layer may be 100 microns, but the amount (concentration) of the active substance is so small that the sheet does not serve half of the claimed life.
For the convenience of layer thickness checking during production, an optical additive can be introduced in the coextrusion layer along with the active additive. The optical additive can be seen under an ordinary ultraviolet lamp or, for example, under lamplight of currency testing device.
Presence of optical additive does not mean existence of active additive, which protects polycarbonate against UV, and moreover, say nothing about its concentration.
It is known that some manufacturers of defective products, in order to reduce production costs, produce sheets with coextrusion layer containing only an optical additive. Thus, in fact the sheets are not protected from exposure to UV and accordingly, from destruction. So when buying you have to be extremely careful.
Some manufacturers claim that their polycarbonate has a UV-additive in the product substance. All manufacturers of polycarbonate feedstock enter into pellets small percentage of UV-stabilizing agents to maintain the raw feedstock during transportation and storage. Concentration of the stabilizing additive is very small and in no way is sufficient to provide necessary protection to finished product.
That is, if the manufacturer claims that the UV additive is contained only in the polycarbonate substance, then this sheet is not at all protected against UV. In order to achieve necessary protection, concentration of UV additives in the polycarbonate substance should be so high that the cost of such a sheet will be exorbitant. There is no manufacturer in the world that works on this principle.
Today there is no better way to protect polycarbonate sheets for a guaranteed period of their service life than coextrusion.
The warranty provided by the Plaza Polygal Company is an indication that the produced material will not lose its physical, mechanical and optical properties (i.e. preserves its impact resistance, do not become turbid, do not turn yellow) during the guaranteed period.
Summarizing all the above, we can say that in choosing polycarbonate it is insufficient to know only the thickness of the UV protection layer, because the buyer has no opportunity to verify the effectiveness of the product protection. In this case, trust the manufacturer guarantees.
It is important to remember:
Side of the sheet protected from ultraviolet radiation is referred to as "external." Care should be taken on the compliance of the manufacturer's recommendations for sheets installation. Otherwise, the complaint will not be accepted by manufacturer.