| 摘要 |
<p>Prodn. of UV-stabilised polyesters comprises (1) heating polyester granules to 150-180 deg. C; (2) mixing a powdered UV stabiliser (I) with the heated granules so that the (I) becomes attached to the granules; (3) drying the powder carrying granules to a moisture content of not more than 0.005 wt.% and (4) forming the dried granules into film, sheet, ribbon, filament, etc. - Pref. the polyester is polyethylene terephthalate and the (I) is chosen from o-hydroxy benzophenones, benzotriazoles, or mixts. of these. Pref. the granules are heated in stage (1) to a temp. at which the surface becomes tacky. Fines may be sepd. from the powder carrying granules between stages (2) and (3). Drying of the granules is pref. carried out at 180-200 deg. C, esp. in a hopper drier from which they are fed directly into an extruder.S Prods. have uniform distribution of UV absorber and give sheets of excellent transparency and resistance to sunlight, and which are free from 'spotting' or uneven degradation on exposure to UV. The sheets are esp. useful in metallised form for controlling heat and glare passing through windows. Since no polyhydric alcohol is used in the prodn. of the sheets, adhesion of the vacuum deposited metal layer is not imparted. (0/0) GBAB- GB2138011 B A process of producing UV-stabilised polyester materials which comprises: (1) heating polyester granules to a temperature at which the polymer surface of the granules becomes soft and tacky; (2) mixing a powdered UV-stabilising substance with said heated granules, thereby producing polyester granules to which said powdered substance is adhered; (3) then subjecting said powder-carrying granules to a drying step effective to reduce the moisture content thereof to no more than about 0.005% by weight; and (4) then forming said dried powder-carrying granules into a useful body.</p> |
