Method for coating phosphor particles, phosphor therethrough and dry electrophotographic screening process using them for a CRT
AssigneeOrion Electric Co., Ltd.
InventorYoung Ho Park
Life of this patent
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Abstract
A method for coating phosphor particles with polymers improves chargeability for use of these particles in CRT screens. The method includes injecting the phosphor particles into a reactor with the use of hexane as the solvent and styrene as a monomer. The particles are agitated and kept hot in the reactor. AIBN is injected into the reactor as a first, second and third catalyst, at one hour intervals. After injecting the third catalyst, a co-catalyst dissolved in hexane is also injected into the reactor. The co-catalyst is cobalt naphthalate. The method then includes cooling, drying, shattering and filtering the particles.
Claims7
A method for coating phosphor particles with polymers in order to improve chargeability thereof in use for manufacturing a screen on an inner surface of a panel of a CRT, said coating method comprising the steps of:
- injecting into a reactor with hexane as a solvent, phosphor particles of about 40 to 60 weight % with respect to the solvent, and styrene as a monomer of about 20 to 30 weight % with respect to the solvent, and agitating them in the reactor;
- maintaining the temperature of the reactor in 60 degrees of centigrade by heating the reactor by a heating mantle and by transferring cool water through a return current cooler mounted on the reactor;
- preparing 2,2′-azobisisobutyronitrile (AIBN) as first, second and third initiators (catalysts) having same amount of about 0.02 to 0.5 weight % with respect to the monomer, injecting into the reactor with the first initiator, injecting into the reactor with the second initiator after lapse of one hour from the time of injecting the first initiator, and finally injecting into the reactor with the third initiator after lapse of two hours from the time of injecting the second initiator;
- injecting co-catalyst dissolved in hexane after the third initiator is injected, co-catalyst being cobalt naphthalate of 0.01 to 0.05 weight % with respect to one of the initiator;
- cooling the reactor after lapse of two hours from the injecting of the co-catalyst;
- drying naturally after completion of the polymerization so as to drive off the solvent or monomers remained in the reactor;
- shattering the resultant dried phosphor particles;
- and
- filtering the shattered phosphor particles with a filter.
Phosphor particles used for a dry electrophotographic screening process for a CRT, wherein polystyrene as a high-molecular polymer is coated on the surfaces of the phosphor particles, the phosphor particles being coated with said polystyrene by a method of immersion polymerization, the method comprising:
- injecting into a reactor with hexane as a solvent, phosphor particles of about 40 to 60 weight % with respect to the solvent, and styrene as a monomer of about 20 to 30 weight % with respect to the solvent, and agitating them in the reactor;
- maintaining the temperature of the reactor in 60 degrees of centigrade by heating the reactor with a hearing mantle any by transferring cool water through a return current cooler mounted on the reactor;
- preparing 2,2′-azobisisobutyronitrile (AIBN) as first, second and third initiators (catalysts) having same amount of about 0.02 to 0.5 weight % with respect to the monomer, injecting into the reactor with the first initiator, injecting into the reactor with the second initiator after lapse of one hour from the time of injecting the first initiator, and finally injecting into the reactor with the third initiator after lapse of two hours from the time of injecting the second initiator;
- injecting co-catalyst dissolved in hexane after the time of injecting the third initiator, co-catalyst being cobalt naphthalate of about 0.01 to 0.05 weight % with respect to one of the initiator;
- cooling the reactor after lapse of two hours from the injecting of the co-catalyst;
- drying naturally after completion of the polymerization so as to drive off the solvent and monomers remained in the reactor;
- shattering the resultant dried phosphor particles;
- and
- filtering the shattered phosphor particles with filter.
A method for manufacturing a screen by dry electrophotographic screening process for a CRT, said method comprising the steps of forming a volatilizable photoconductive layer on a volatilizable conductive layer coated on the inner surface of panel, charging the photoconductive layer to contain uniformly electrostatic charges, exposing the photoconductive layer selectively by a light source using a shadow mask, and developing the exposed areas of the photoconductive layer with one of first to third phosphor particles which are charged by a discharge electrode or a generator of triboelectricity, wherein;
- at least one kind of phosphor particles of the first to third phosphor particles used at the developing step are coated with polystyrene as a high-molecular polymer on the surfaces thereof.
Dependencies are inferred from the claim text.