Coating processes – Optical element produced – Transparent base
Patent
1982-07-29
1983-07-12
Hoffman, James R.
Coating processes
Optical element produced
Transparent base
65 6052, 427110, 427160, B05D 112, C03C 1723
Patent
active
043930980
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a process for developing a coating film on a surface of a sheet of glass, the sheet of glass being at a temperature in the range from 510.degree. C. to 625.degree. C. In particular, the process has been developed for placing such a coating film on a sheet of glass as that sheet is being moved in a selected direction from a glass manufacturing process. The inventive process is one in which the surface of the heated glass sheet is engaged with a powder spray composition which comprises a plurality of hollow, generally spherical particles which are formed from heat decomposable, organo-metallic salts of at least two metals. The coating film is placed on the sheet of glass so as to alter the light transmission characteristics of that glass sheet.
BACKGROUND ART AND PRIOR ART STATEMENT
A history of the pyrolytic application of powder coatings to the surface of a glass sheet is set forth hereinbelow.
U.S. Pat. No. 3,081,200, in column 3, line 13, shows that the patentee has sprayed both solutions and powder in order to form pyrolytic metal oxide coatings on a heated glass sheet. The patent examples, however, are directed to solutions of coating materials and no specific instructions are contained in the patent with respect to how one successfully accomplishes the application of powders to form a pyrolytic metal oxide film on a glass sheet. Also, the patent contains no instructions with respect to the manner of making up a powder which may be successfully applied to a glass sheet to form a pyrolytic coating film thereon.
German Pat. Nos. 2,529,076; 2,529,077; and 2,529,079 deal with the development of a metal oxide film on a glass sheet.
In German Pat. No. 076, metal salt particles are charged prior to application to a glass sheet which has been preheated to a temperature in the range from 500.degree.-650.degree. C. The patent indicates that heat decomposable, organic based metal salts may be used and that a preheated carrier gas may be used for transporting the particles to the glass sheet. The patent teaches that the particles should be charged and distributed in a 90.degree. downwardly directed attitude toward the glass sheet from a gas distributor which extends transverse to the direction of travel of the glass sheet passing therebelow.
German Pat. No. '077 discloses a process for forming a metal oxide film on a glass sheet by pyrolytic techniques. The starting material is a powder metal compound which is carried by an inert carrier gas into a cyclone where the smallest particles of the compound are separated from the coarser particles, subsequently carried along by the carrier gas flow to the surface of the glass sheet to be coated. The coarser particles are collected then partly evaporated under an inert atmosphere by heating. Thereafter, the resulting metal compound vapors are mixed with the carrier gas which carries the finer particles to the surface to be coated. Thus the patent teaches the simultaneous application of both relatively fine heat decomposable, organic based metal salts and vaporized material of the same nature to the glass surface which is to have a metal oxide film developed thereon.
German Pat. No. '079 discloses a method in which relatively large particles of a heat decomposable material are dropped on a glass sheet to develop a film thereon.
U.S. Pat. No. 3,852,098 discloses a process in which a glass sheet is coated with a metal containing film by heating the glass and contacting the hot glass with a gaseous mixture. The patent does not deal with the application of powder materials directly to the surface of the glass to develop a metal oxide coating thereon. Rather, the process disclosed is one which uses as the coating media a gaseous mixture containing 40-100% by volume of the vapors of a reactive metal compound. The mixture is heated by the glass to a sufficient temperature, causing the metal vapor compound to react, thereby depositing the coating film.
U.S. Pat. No. 4,182,783 is a patent directed to a vapor deposition process for achie
REFERENCES:
patent: 3081200 (1963-03-01), Tompkins
patent: 3852098 (1974-12-01), Bloss et al.
patent: 4182783 (1980-01-01), Henery
patent: 4188199 (1980-02-01), Van Lagthem et al.
patent: 4320271 (1980-10-01), Marcault
Schwei Lawrence J.
Stinson Wilbur G.
Vong Sandy T. S.
Ford Motor Company
Hoffman James R.
Johnson Olin B.
Johnson William E.
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