Pilkington Brothers P.l.c.

The Plessey Company Plc

William Ramsey Maltman

Colin Robert Howard

Stephen N Oliver

David Gordon Loukes

Martin W Baskerville

Ian M Threlfall

A direct casting process for manufacturing a shaped synthetic plastic article, such as an ophthalmic lens, which has photochromic properties, the process comprising incorporating a photochromic spiro-oxazine compound into a mixture comprising a highly reactive polyfunctional monomer and a low amount of a polymerization catalyst, and curing the composition in a mould to form the shaped synthetic plastic article.

Process for manufacturing photochromic articles

A method is disclosed for manufacturing transparent plastic articles, primarily plano or opthalmic photoreactive lenses, which comprises incorporating fulgides or fulgimides containing an adamantylidene group in plastics casting or moulding compositions or preformed plastics articles and converting the fulgide or fulgimide in situ into a form in which it confers on the article the property of darkening in the presence of sunlight and fading in its absence.

Photochromic compounds and their use in photoreactive lenses

Patterned float glass is manufactured by locating in contact with the float ribbon, while it is hot, a shaped molten body of a material for modifying the glass surface. The configuration of the molten body is progenitive of a pattern to be introduced into the glass and ionic migration is engendered electrically between the molten body and the glass in a sequence of defined time periods to produce a pattern of modified glass in the ribbon surface.

Manufacture of float glass

Surface modified glass is produced by method and apparatus in which the glass is contacted with a molten body, for example of a molten metal or molten alloy while the glass temperature is such that it can be modified by migration of cations from the molten body into the glass surface. This cationic migration is electrically induced and the molten material is periodically connected as a cathode with respect to the glass for a preset time sufficient at least partially to deoxidise the molten material. Non-oxidising conditions may be maintained in the molten material and the electrical action at the interface between the molten body and the glass while the molten body is connected as a cathode causes reduction of at least a proportion of the cations in the glass surface to produce a metallic dispersion. The invention is particularly applicable to the modification of the upper surface of a ribbon of float glass advancing along a molten metal bath.

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St. Helens, United Kingdom

William Ramsey Maltman