Workable Specification For Cast Filters
Cast allyl carbonate is a high quality substrate for optical filters. However this is still a plastic material, and although Slater Plastics take every care in its production, blemishes do occur. These blemishes take the form of small inclusions and fine, trapped fibres.
So that Slater Plastics can quantify the quality of products made from allyl carbonate, it is important to lay down a specification and inspection criteria. This is a specification that we feel is obtainable and repeatable, when viewed against our past performance. With individual project discussions, it may be possible to tighten up the specification, but this will be done by inspecting out defects and will have obvious implications on price.
The panel should be viewed from the front face under daylight conditions, with normal non-directional lighting. Viewing should take 15 seconds and from a distance of 450 mm.
Small fibres in cast allyl carbonate are not like the surface fibres in coated material. In coatings the fibre creates an inclusion on the surface which is highly visible. With the cast product fibres are very fine and are trapped within the material. These are difficult to see and do not produce a surface defect. These fibres are only visible when illuminated with a direct, bright light and do not effect the quality of a display.
No scratches > 0.01 mm wide are allowed
Please be assured that we will attempt to produce the best quality panels that we can at all times. This specification is an indication of worst case conditions.
Fire Specification For Allyl Diglycol Carbonate
Slater Plastics manufactures cast filters from allyl diglycol carbonate ( ADC monomer ). The following information details the burning characteristics of the cast polymer. These details have been obtained from a variety of sources, including the manufacturer of the monomer, but no certification is available for these results. All details are given for information purposes only and if certification is required an independent test will need to be carried out. The details have been assessed and checked by Slater Plastics and are believed to be correct.
UL Fire Rating
Polymer cast from ADC has been tested in America and has passed UL94 HB at 1 mm and 1.5 mm thickness. This test requires a flame spread of less than
75 mm / minute for less than 3 mm thick, or less than 40 mm / minute for greater than 3 mm. Other flame spread tests back up this result.
For 1.3 – 2.9 mm thick - to ASTM D 635 - < 25 mm
For 4 mm thick - result from monomer manufacturer- 25 mm
Limiting Oxygen Index
Any oxygen index below 21 % means that the material will burn in air. This polymer has an index of 18.3 %. This is slightly better than acrylic at about 17 % but worse than polycarbonate at 25 %.
Self Ignition Temperature
Self-ignition temperature is 720 º F according to ASTM D 1929.
Products of Burning
If the polymer is 100 % burned, the products are CO2 and H2O. The products of incomplete combustion will also include some CO, propene and some soot with phenolic end groups on the surface. ( OH attached to aromatic ring ). Toxic substances are not expected.
Unlike some other optical plastics on fire, this polymer does not drip burning material.
Slater Plastics will supply samples to any customer wishing to carry out independent testing.