Positive-working photoresist composition and method for forming a light-absorbing matrix in a color CRT structure

Claim 1

A method of providing a color cathode ray tube screen including a viewing panel and discrete color luminescing areas responsive to electron excitation positioned on the inner surface of said viewing panel with a black, light-absorbing matrix separating said color luminescing areas, said method comprising the steps of: (a) providing on a surface of the inner surface of the viewing panel of a glass cathode ray tube envelope a thin aqueous layer of 3-7% by volume mixture in water of about 1 mole of approximately polyvinyl acetate 88% hydrolyzed to; polyvinyl alcohol, about 0.5-1.5 moles of 1,4-butanediol, about 0.5-1.5 moles of ammonium trioxalatoferrate, about 0.05-0.07 mole of ferric nitrate and about 3-12 moles of finely divided graphite or lampblack; (b) drying said thin aqueous layer at room temperature for about 15-180 seconds to cause said thin layer to become immobile; (c) exposing areas of said thin layer corresponding to said color luminescing areas to ultra-violet radiation for a time sufficient to cause said exposed areas to become water soluble. (d) heating said thin layer at a temperature of about 95°-120° F. for about 1-3 minutes to thereby remove the remainder of water from said thin layer matrix and render water-insoluble the unexposed areas of said layer; (e) removing the exposed portions of said layer from said surface by developing said layer with water, thereby providing said surface with a black, light absorbing, matrix surrounding areas of said surface suitable for coating by phosphors for forming said color luminescing areas.

Claim 2

A method of providing a color cathode ray tube screen including a viewing panel and discrete color luminescing areas responsive to electron excitation positioned on the inner surface of said viewing panel with a black, light-absorbing matrix separating said color luminescing areas, said method comprising the steps of: (a) providing on a surface of the inner surface of the viewing panel of a glass cathode ray tube envelope a thin aqueous layer of 3-7% by volume mixture in water of about 1 mole of approximately polyvinyl acetate 88% hydrolyzed to; polyvinyl alcohol, about 0.5-1.5 moles of 1,4-butanediol, about 0.5-1.5 moles of ammonium trioxalatoferrate, about 0.05-0.07 mole of ferric nitrate and about 3-12 moles of finely divided graphite or lampblack; (b) drying said thin aqueous layer at room temperature for about 15-180 seconds to cause said thin layer to become immobile; (c) exposing areas of said thin layer corresponding to said color luminescing areas to ultra-violet radiation for a time sufficient to cause said exposed areas to become water soluble. (d) heating said thin layer at a temperature of about 95°-120° F. for about 1-3 minutes to thereby remove the remainder of water from said thin layer matrix and render water-insoluble the unexposed areas of said layer; (e) removing the exposed portions of said layer from said surface by developing said layer with water, thereby providing said surface with a black, light absorbing, matrix surrounding areas of said surface suitable for coating by phosphors for forming said color luminescing areas.