The remainder is polyether. A next focal point of the research is to boost this to 100 percent. Although polycarbonate performance continues to improve, progress also continues with regard to cheaper materials, particularly polyester, making them competitive with polycarbonate for some applications. For example, Tsutsunaka Plastic last year began sales of a polyester sheet which features both optical transparency and high shock resistance. Transparency is comparable to polycarbonate at 87 percent, but is lower than the 93 percent for acrylic sheet.
Shock resistance is about four times that of sheet acrylic plastic, but less than for polycarbonate.
The sheets are formed by extruding an amorphous polyester. They are available in thicknesses ranging from 0.5mm to 5.0mm in 0.5mm increments. Curved shapes can be produced by using special heaters. The price is slightly higher than for acrylic but far below polycarbonate. A major application is expected to be large sized, high strength, transparent covers, including for vending machines, industrial production equipment and game machines.