US3652323A - Process for coating flatlike surfaces - Google Patents

Process for coating flatlike surfaces Download PDF

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Publication number
US3652323A
US3652323A US887267A US3652323DA US3652323A US 3652323 A US3652323 A US 3652323A US 887267 A US887267 A US 887267A US 3652323D A US3652323D A US 3652323DA US 3652323 A US3652323 A US 3652323A
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United States
Prior art keywords
coating material
axis
process defined
rotating
panel
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Expired - Lifetime
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US887267A
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English (en)
Inventor
Bradford Knox Smith
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RCA Licensing Corp
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RCA Corp
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Assigned to RCA LICENSING CORPORATION, TWO INDEPENDENCE WAY, PRINCETON, NJ 08540, A CORP. OF DE reassignment RCA LICENSING CORPORATION, TWO INDEPENDENCE WAY, PRINCETON, NJ 08540, A CORP. OF DE ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: RCA CORPORATION, A CORP. OF DE
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J9/00—Apparatus or processes specially adapted for the manufacture, installation, removal, maintenance of electric discharge tubes, discharge lamps, or parts thereof; Recovery of material from discharge tubes or lamps
    • H01J9/20—Manufacture of screens on or from which an image or pattern is formed, picked up, converted or stored; Applying coatings to the vessel
    • H01J9/22—Applying luminescent coatings
    • H01J9/221—Applying luminescent coatings in continuous layers
    • H01J9/223—Applying luminescent coatings in continuous layers by uniformly dispersing of liquid
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D1/00—Processes for applying liquids or other fluent materials
    • B05D1/002—Processes for applying liquids or other fluent materials the substrate being rotated

Definitions

  • This invention relates to a novel process for coating a flatlike surface of an article and particularly, though not necessarily exclusively, to a process for coating the inner surface of the glass viewing panel for a cathode ray tube.
  • color television picture tube includes a light-absorbing matrix as part of the luminescent screen structure.
  • This type of tube has been described previously; for example, in US. Pat. Nos. 2,842,697 to F. J. Bingley and 3,146,368 to J. P. Fiore et al.
  • These patents describe color television picture tubes of the aperture-mask type (also called shadow-mask type) in which a light-absorbing matrix is located on the inner surface of the viewing window of the tube.
  • the matrix has a multiplicity of holes therein, each phosphor dot of the luminescent screen filling one hole in the matrix.
  • a pattern of polymeric dots is produced on the inner surface of the viewing window where the holes in the matrix are to be located.
  • the surface and polymeric dots are then overcoated with a liquid suspension or slurry containing matrix material, such as graphite, and then dried. Then, the polymeric dots are removed taking with them the overlying matrix material but leaving the matrix material adhered to the inner surface around the areas previously occupied by the polymeric dots.
  • the step of overcoating the window and polymeric dots with a suspension containing matrix material was carried out in the factory by dispensing a quantity of the suspension upon the inner surface of a slowly rotating panel facing upward, rotating and tilting the panel to spread the suspension over the inner surface and then dumping or spinning off the excess suspension. While this procedure produces good coatings, the suspension has a tendency to flow over the edge, down the outer surfaces of the sidewalls and across the outer surface of the viewing window. The outer surfaces of the viewing window and of the sidewalls must then be cleaned, usually by hand, to remove this matrix material in order to produce a satisfactory product.
  • the novel process comprises slowly rotating a downwardfacing, flatlike surface to be coated about an axis that is substantially normal to the surface, and preferably with the axis at about 30 from the vertical.
  • a stream of liquid coating material is projected in a trajectory to contact the slowly rotating surface substantially tangentially and then to pass along the surface through the axis and then radially across the surface.
  • the stream is stopped and the excess coating material is permitted to drain from the rotating surface.
  • the suspension no longer tends to travel over the outer surfaces of the panel, thereby eliminating a manual cleaning step.
  • the suspension travels at most over the edge and up the outer sidewalls only a short distance, which is easily removed by mechanical means.
  • the coating step is completed more rapidly and the inner sidewalls are completely coated.
  • FIG. 1 is a sectional elevation of the viewing panel of a cathode ray tube being coated by the novel process at the preferred angle of about 30.
  • FIGS. 2 and 3 are sectional elevations of viewing panels for cathode ray tubes being coated by the novel process at angles of about 0 and respectively from vertical.
  • the panel 21 is generally bowl shaped comprising a viewing window 25 including a flatlike inner surface 27 and an outer surface 28. Sidewalls 29, having inner surfaces 31 and outer surfaces 33, rise from the edge of the viewing window 25 to define a generally rectangular configuration.
  • the axis 23 is generally normal to and centrally located to the inner window surface 27 (which is to be coated) of the viewing window 25.
  • the axis 23 is inclined from a vertical axis 35 by about 30. A pattern of polymeric dots adheres to the inner window surface 27.
  • the panel 21 is slowly rotated at about 6 to 10 rpm. about the axis 23 while a stream 37 of liquid coating material issues from an 0.25-inch (inside diameter) nozzle 39 under about 3.2 pounds-per-square-inch pressure. With this small pressure behind it, the stream is said to be limp and follows an arcing trajectory.
  • the nozzle 39 is so located that the stream 37 is projected to contact the inner window surface 27 substantially tangentially above the axis 23, so that the coating material passes, after contact with the surface, through the axis and then radially across the inner surface 27.
  • the liquid coating material is an aqueous suspension containing about 5 percent by weight of colloidal graphite. This suspension has a viscosity of less than 2.5 centipoises and a pH of about 10.
  • the coating material Upon contact, the coating material follows the inner surface 27 because of interfacial tension and'then passesdown the inner sidewall surface 31 and drips off the edge 41 by gravity. A small amount of coating material passes over the edge 41 and up the outer sidewall surface 33, a distance less than about 0.50 inch.
  • the stream is continued while the panel 21 is rotated at least one revolution, preferably about 1.2 revolutions, to assure overlapping coverage.
  • the stream 37 is stopped and rotation is continued while the excess coating material drains by gravity and the coating dries.
  • the rotation may be increased at this point, for example, to about rpm. to aid in controlling the thickness of the coating.
  • drying may be accelerated by applying radiant heat to the coating.
  • Coating material which is deposited upon the edge 41, the outer sidewall surface 33 and the stud 43, may be removed while the panel is rotating by applying thereto a jet of water with or without the aid of the mechanical action of a brush or sponge. After cleaning and drying are completed, the coated panel may be treated to remove the polymeric dots and overlying coating, while retaining the coating material around the areas previously occupied by the dots.
  • the viewing panel 21 is then removed from its holder and the cycle may be repeated with another panel.
  • the novel process may be applied to coating flatlike surfaces other than the inner surfaces of round or rectangular viewing panels for cathode ray tubes.
  • the phrase flatlike surfaces is intended to include concave and convex surfaces with a shallow curvature.
  • the axis of rotation is best inclined at angles in the range of about 5 to 60 from the vertical.
  • FIG. 2 shows the novel process being carried out on a viewing panel rotating about an axis 23a which is vertical; that is, the axis is said to be inclined 0 from vertical. In this position, the coating material does not deposit as far up the outer sidewall surface 33a, but the nozzle 39a is more difficult to position, and drainage from the central portion of the viewing window 25 is slower.
  • FIG. 1 shows the novel process being carried out on a viewing panel rotating about an axis 23a which is vertical; that is, the axis is said to be inclined 0 from vertical. In this position, the coating material does not deposit as far up the outer sidewall surface 33a, but the nozzle 39a is more difficult to position
  • FIG. 3 shows the novel process being carried out on a viewing panel which is rotating about an axis 23b which is inclined at about 60 from vertical. In this position, the nozzle 39b is more easily positioned, coating and draining of the coating material are more rapid, but the coating material deposits further up the outer sidewall surface 33b.
  • the nozzle size and the pressure on the coating material at the nozzle are not critical except that a limp stream should be produced so that, at the point of contact of the stream with the surface to be coated, substantially tangential contact is achieved. With this tangential contact, substantially no erosion or scouring of the structure or coatings, such as polymeric dots, on the inner surfaces occurs. Also, the coating material spreads by its own momentum guided in part by its own wetting characteristics. High velocities and angles substantially greater than tangential cause the liquid coating material to bounce off the inner surface leaving bare spots and'requiring equipment to recover the splash or spray produced. Spraying the coating material (instead of limp stream application) produces the same difficulties, though to a somewhat different degree. Pressures of 5 pounds per square inch and less are preferred. In the novel process, a solid stream of liquid coating material is applied with substantially no spray or splash produced.
  • the liquid coating material' may be of any composition.
  • the coating suspension preferably contains 4.5 to 6.5 percent by weight of colloidal graphite. Part or all of the graphite in the example may be replaced with other particulate materials, with or without a binder.
  • Some other light-attenuating materials that may be used for making a light-absorbing matrix are other forms of carbon such as carbon black and acetylene black, and other pigments, such as ferrous oxide and manganese dioxide.
  • the novel process may be used for depositing any pigmented or unpigmented liquid coating composition of relatively low viscosity upon a flatlike surface.
  • the liquid coating composition must have a sufficiently low viscosity to be projected as a stream and then to flow across the surface to be coated.
  • the lower the viscosity the faster the surface can be covered and drained of excess coating material.
  • viscosities of about 1 to 50 centipoises can be used, preferably about 5 centipoises and lower.
  • the lower the viscosity the faster may be the speed of rotation of the surface to be coated.
  • the speed of rotation should be such that wetting of thesurface by the coating material advances uniformly without missing any surface areas.
  • the surface be rotated at least about 1.2 revolutions during application to assure complete coating of the surface.
  • Low rotational speeds assure that good coating can be obtained without producing voids and without using an sists essentially of particles of light-attenuating material in a excessive volume of coating material. Small voids are difi'icult to cover in a subsequent pass due to the presence of an established wetted path.
  • the stream be provided in a smooth flow of liquid coating material. This may be achieved conveniently with pressures produced from a head tank.
  • the stream is stopped but the rotation of the surface is continued. Rotation aids in smoothing the applied material quickly.
  • the rotational speed may be increased, up to about rpm. As the rotational speed is increased, centrifugal forces become greater and accelerate the draining and smoothing of the applied material, especially near the edge of the surface. However, centrifugal forces do tend to drive excess coating material further up the outside surfaces of the sidewalls.
  • a process for coating 5 flatlike surface comprising a. slowly rotatin g said surface facing downward about a axis that is susbstantially normal to the surface,
  • a process for coating the inner flatlike surface of the viewing panel of a cathode ray tube comprising a. supporting the panel with said inner surface facing downward,
  • liquid coating material has a viscosity of 50 centipoises or less and convolatile liquid.
  • liquid coating material consists essentially of colloidal graphite particles in water.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Application Of Or Painting With Fluid Materials (AREA)
  • Formation Of Various Coating Films On Cathode Ray Tubes And Lamps (AREA)
  • Surface Treatment Of Glass (AREA)
  • Vessels, Lead-In Wires, Accessory Apparatuses For Cathode-Ray Tubes (AREA)
US887267A 1969-12-22 1969-12-22 Process for coating flatlike surfaces Expired - Lifetime US3652323A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US88726769A 1969-12-22 1969-12-22

Publications (1)

Publication Number Publication Date
US3652323A true US3652323A (en) 1972-03-28

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US887267A Expired - Lifetime US3652323A (en) 1969-12-22 1969-12-22 Process for coating flatlike surfaces

Country Status (7)

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US (1) US3652323A (fr)
JP (1) JPS5025496B1 (fr)
CA (1) CA942596A (fr)
FR (1) FR2074062A5 (fr)
GB (1) GB1314690A (fr)
NL (1) NL165954C (fr)
SU (1) SU413668A3 (fr)

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3911175A (en) * 1972-01-28 1975-10-07 Oleg Nikolaevich Chemeris Method and a device for gunniting converter
JPS51143047A (en) * 1975-06-04 1976-12-09 Hitachi Ltd Spin coater
US4078095A (en) * 1974-03-28 1978-03-07 Rca Corporation Slurry process for coating particles upon the viewing-window surface of a cathode-ray tube
US4542038A (en) * 1983-09-30 1985-09-17 Hitachi, Ltd. Method of manufacturing cathode-ray tube
US4729907A (en) * 1987-02-24 1988-03-08 Rca Corporation Method of making a viewing screen structure for a cathode-ray tube
US4842894A (en) * 1985-09-20 1989-06-27 U.S. Philips Corporation Method of vapor depositing a luminescent layer on the screen of an x-ray image intensifier tube
DE4036239A1 (de) * 1990-11-14 1992-05-21 Nokia Unterhaltungselektronik Verfahren zum lackieren der leuchtstoffschicht einer farbbildroehre
US5145511A (en) * 1991-11-08 1992-09-08 Videocolor Spa Method for manufacturing a metallized luminescent screen for a cathode-ray tube
US5178906A (en) * 1991-04-09 1993-01-12 Videocolor Method of manufacturing a phosphor screen for a CRT using an adhesion-promoting, blister-preventing solution
US5366759A (en) * 1990-11-14 1994-11-22 Nokia (Deutschland) Gmbh Method of lacquering the luminophore layer of a color picture tube
US5707682A (en) * 1996-05-16 1998-01-13 Videocolor S.P.A. Method of manufacturing a phosphor screen
US6228421B1 (en) * 1998-09-29 2001-05-08 Matsushita Electronics Corporation Method for manufacturing a cathode ray tube
US6461705B2 (en) * 2000-02-24 2002-10-08 Glass Unlimited Of High Point, Inc. Glass panel with simulated metal strip
US6592420B1 (en) * 1999-06-18 2003-07-15 Matsushita Electric Industrial Co., Ltd. Manufacturing method for a glass substrate having a phosphor layer used as a color cathode ray tube front panel and a color cathode ray tube manufacturing method
US20040014874A1 (en) * 2000-11-23 2004-01-22 Saija Leo Mario Aqueous polymeric dispersion and application in cathodic tubes

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2721809A (en) * 1952-09-10 1955-10-25 Alvin M Marks Method for the uniform coating of large surfaces
US2763233A (en) * 1953-11-25 1956-09-18 Gen Electric Automatic machine for coating cathode ray tube bulbs
US2792810A (en) * 1954-03-01 1957-05-21 Sylvania Electric Prod Article handling device
US3376153A (en) * 1964-10-20 1968-04-02 Rauland Corp Method of coating cathode-ray tubes
US3440081A (en) * 1965-12-20 1969-04-22 Sylvania Electric Prod Method for the fabrication of image display screens

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2721809A (en) * 1952-09-10 1955-10-25 Alvin M Marks Method for the uniform coating of large surfaces
US2763233A (en) * 1953-11-25 1956-09-18 Gen Electric Automatic machine for coating cathode ray tube bulbs
US2792810A (en) * 1954-03-01 1957-05-21 Sylvania Electric Prod Article handling device
US3376153A (en) * 1964-10-20 1968-04-02 Rauland Corp Method of coating cathode-ray tubes
US3440081A (en) * 1965-12-20 1969-04-22 Sylvania Electric Prod Method for the fabrication of image display screens

Cited By (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3911175A (en) * 1972-01-28 1975-10-07 Oleg Nikolaevich Chemeris Method and a device for gunniting converter
US4078095A (en) * 1974-03-28 1978-03-07 Rca Corporation Slurry process for coating particles upon the viewing-window surface of a cathode-ray tube
JPS51143047A (en) * 1975-06-04 1976-12-09 Hitachi Ltd Spin coater
JPS5327287B2 (fr) * 1975-06-04 1978-08-08
US4542038A (en) * 1983-09-30 1985-09-17 Hitachi, Ltd. Method of manufacturing cathode-ray tube
US4842894A (en) * 1985-09-20 1989-06-27 U.S. Philips Corporation Method of vapor depositing a luminescent layer on the screen of an x-ray image intensifier tube
US4729907A (en) * 1987-02-24 1988-03-08 Rca Corporation Method of making a viewing screen structure for a cathode-ray tube
US5366759A (en) * 1990-11-14 1994-11-22 Nokia (Deutschland) Gmbh Method of lacquering the luminophore layer of a color picture tube
DE4036239A1 (de) * 1990-11-14 1992-05-21 Nokia Unterhaltungselektronik Verfahren zum lackieren der leuchtstoffschicht einer farbbildroehre
US5334410A (en) * 1990-11-14 1994-08-02 Nokia Unterhaltungselektronick Gmbh Method of lacquering the luminophore layer of a color picture tube
US5178906A (en) * 1991-04-09 1993-01-12 Videocolor Method of manufacturing a phosphor screen for a CRT using an adhesion-promoting, blister-preventing solution
US5145511A (en) * 1991-11-08 1992-09-08 Videocolor Spa Method for manufacturing a metallized luminescent screen for a cathode-ray tube
US5707682A (en) * 1996-05-16 1998-01-13 Videocolor S.P.A. Method of manufacturing a phosphor screen
US6228421B1 (en) * 1998-09-29 2001-05-08 Matsushita Electronics Corporation Method for manufacturing a cathode ray tube
US6592420B1 (en) * 1999-06-18 2003-07-15 Matsushita Electric Industrial Co., Ltd. Manufacturing method for a glass substrate having a phosphor layer used as a color cathode ray tube front panel and a color cathode ray tube manufacturing method
US6461705B2 (en) * 2000-02-24 2002-10-08 Glass Unlimited Of High Point, Inc. Glass panel with simulated metal strip
US6524674B1 (en) * 2000-02-24 2003-02-25 Glass Unlimited Of High Point, Inc. Glass panel with simulated metal strip
US6752891B2 (en) * 2000-02-24 2004-06-22 Glass Unlimited Of High Point, Inc. Glass panel with simulated metal strip
US20040014874A1 (en) * 2000-11-23 2004-01-22 Saija Leo Mario Aqueous polymeric dispersion and application in cathodic tubes

Also Published As

Publication number Publication date
GB1314690A (en) 1973-04-26
DE2059786A1 (de) 1971-09-02
FR2074062A5 (fr) 1971-10-01
JPS5025496B1 (fr) 1975-08-23
SU413668A3 (fr) 1974-01-30
NL165954C (nl) 1981-06-15
CA942596A (en) 1974-02-26
NL165954B (nl) 1981-01-15
NL7014985A (fr) 1971-06-24
DE2059786B2 (de) 1977-06-02

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Date Code Title Description
AS Assignment

Owner name: RCA LICENSING CORPORATION, TWO INDEPENDENCE WAY, P

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:RCA CORPORATION, A CORP. OF DE;REEL/FRAME:004993/0131

Effective date: 19871208