Patent GB-940399-A (GB)
Title: Method and apparatus for forming a film on a glass surface
Inventor: BROWNE CHARLES MERMYN
IPC: C03C17/00
Filed: 1961-04-06
Abstract: A method of producing filmed and tempered bent glass sheets, in particular automobile windscreens and rear windows, to produce low light transmittance and high solar radiation reflection, comprises supporting a glass sheet for movement along a horizontal path normal to the longitudinal axis of the sheet, passing the sheet through a zone of controlled heating to bend it to the desired contour and then passing the sheet through a zone of controlled cooling to temper it and spraying the sheet with a filming solution of a metal salt or metallo-organo compound, the spraying source being moved transversely to the path of travel of the sheet and being maintained at a uniform distance from the sheet.  The sheet may be sprayed at a temperature above 600 DEG  F. and the coating formed may contain the oxide of Sn, Ti, Cd, In, Fe, Mn, Co or mixtures thereof.  Fig. 1 shows a car 20, the interior surface 23 of the rear window 21 of which has been coated with film 22.  The film 22 has major area 24 where light transmittance is restricted to the greatest extent, bordered by fade-out line 25 that defines fade-out area 26 in which the transmittance gradually increases till it reaches the clarity of the unfilmed area 27.  The filming solution is preferably one which will produce a filmed area 24 having a daylight transmittance of 28 to 36% and 22 to 31% and a solar radiation reflectance of 18 to 23% and 10 to 13% when used on clear or regular plate glass and heat-absorbing glass respectively. The fade-out area 26 will have light transmittance gradually increasing to 87 to 88% and 72 to 76% and solar radiation reflection decreasing to 8% and 6% for clear glass and heat-absorbing glass, respectively.  The atomization of the spray may be accomplished by steam, inert gas or air. It may be necessary to keep the filming solution cool, e.g. by surrounding the spray nozzles with a cooling condenser, and also to continually circulate the solution. The sheet may be masked in certain <PICT:0940399/C1/1> <PICT:0940399/C1/2> areas by conventional masking means.  In the preferred embodiment this is done by exhaust vapours causing an air current across the sheet in the direction of sheet travel to eliminate any back spray.   A mould 30 supporting a glass sheet 34, which mould is situated on a travelling conveyer 28, is passed through a bending furnace 31, a tempering zone 32 in which the sheet is subjected to cooling air forced through manifolds 39 and 41 by fans (not shown) and a spray station 33 in which the sheet is held stationary. Before the mould 30 is arrested by mould stop 54 in the spraying station 33, it strikes a timer switch 52 which activates a timer 53 which results in operation of spray means 78. The spray means 78 comprises spray nozzles 79 which are mounted on the lowermost end of a movable carriage 74, driven by motor 76, the upper end of which carriage 74 is carried by suitable rollers 82 resting upon contoured cam bars or tracks 83a and 83b. In movement the carriage 74 is thus <PICT:0940399/C1/3> <PICT:0940399/C1/4> raised and lowered as the rollers 82 follow the contour of the cam bars 83a and the spray nozzles 79 are kept in parallel relationship to the contour of the sheet 34 as the rollers follow cam bar 83b. When sufficient solution has been sprayed the timer 53 terminates the operation of spraying and initiates the operation of moving the mould stop 54 out of a stopping position and thus the mould 30 moves on. The mould 30 hits a switch 111 which initiates the operation of returning mould stop 54 to an arresting position. The mould 30 may be recycled.