DE3045970A1 - Applying pigment to surface of fluorescent grains - by grinding, and fixing with resin emulsion - Google Patents

Abstract

In a process for the adhesive applicn. of dye-pigments to the surface of fluorescent grains, (a) the pigment is ground onto the surface of the grains, followed by (b) treatment with a resin emulsion as fixative, and (c) drying, esp. at increased temp. Used esp. for the fluorescent screen of a cathode ray tube, esp. a colour image tube, coated with pigmented fluorescent substance, esp. fluorescent substances encased in pigments. Bonding between the pigment and the fluorescent grains is improved. The washing stages of the wet appln. process are avoided. Neither the pigment nor the grains need to be pre-ground. Any fluorescent substance can be encased in any pigment.

Description

Method for applying color pigments

Phosphor grains The invention relates to a method for firmly adhering Application of color pigments to the surface of phosphor grains, treatment with a resin emulsion as a fixing agent and drying, in particular at an elevated temperature.

To increase the contrast of the fluorescent screens of color cathode ray tubes it is known to color at least one of the individual phosphors on the surface (to be pigmented). In particular the red fluorescent substances used in color cathode ray tubes based on rare earth oxide or rare earth oxysulphide, as well as the blue fluorescent substances used Zinc sulfide-based are mixed with a red pigment, such as cadmium sulfoselenide or iron oxide red or a blue pigment, e.g. cobalt blue or ultramarine blue encased. The pigment is wet using organic or inorganic glue applied.

The individual work steps in the production of fluorescent screens for color picture tubes can lead to the pigmented phosphor grains the pigment is partially rubbed off. There is a correspondingly low contrast the loss of pigment. In addition, however, there is pigment contamination that has already occurred before attached fluorescent strips or dots. This changes the Ijmission character as well as the light output.

The invention is based on the object of improving the pigments To give adhesion to the fluorescent surface, and if possible with savings the washing process for pigments applied by wet means.

This is achieved with a method of the type mentioned at the beginning Surprisingly in that the pigment swelled onto the surface of the phosphor will.

The rubbing is preferably carried out in a mortar grinder.

According to an expedient embodiment, the pigment is and also the luminescent material only deglollers when rubbed on.

Despite the simpler procedure (the wet route is bypassed) is the adhesion of the pigments to the phosphor surface is improved. By rubbing under pressure, neither the phosphor nor the pigment have to be ground beforehand.

According to a preferred embodiment of the invention, the pigment adhesion on the fluorescent surface additionally by rubbing on a polymerizable Reinforced resin emulsion, in particular an already prepolymerized resin emulsion. The phosphor pigmented in this way is at temperatures between 18 and 250C, preferably dried at 160C.

The pigmented phosphor is hydrophilic, so it can be mixed with water wet well.

The phosphor grains provided with color pigments are suitable for Manufacture of screens for cathode ray tubes, in particular picture tubes.

The field of application of the method according to the invention is universal: all currently known phosphors can essentially be used with all currently known known pigments.

The method of the invention in which the pigment is rubbed off fixed to the phosphor surface and optionally for improved adhesion with a polymerizable, in particular prepolymerized, resin emulsion Rubbing is aftertreated, rubbing in a mortar grinder, pearl mill or ball mill can be made, will be described in more detail.

The phosphor to be pigmented is used together with the desired amount of pigment Mix well outside or inside a mortar grinder. The mixture is considered complete, when the color tone no longer inserts, which is indicated visually or by measurement can be. The l'igmcnt is then placed in the mortar aliilllc by a pestle rubbed under pressure on the phosphor surface. Here are how already mentioned, agglomerates, which can be present in the phosphor but also in the pigment, eliminated at the same time. The contact pressure can vary and in particular the sensitivity of the luminescent material or

of the pigment.

A certain amount of a polymerizable or already prepolymerized resin emulsion, diluted with water or alcohol, added and rubbed off. The phosphor is then at a temperature between 18 and 2500 C, preferably dried at 1600 C.

The application of the procedure is pretty universal. It can be Phosphors on a wide variety of bases, such as sulfides, oxysulfides, silicates, Oxides, phosphates, halophosphates, oxyhalides, burrs, vanadates, fluorides, borates pigment etc.

The following examples explain the invention without limiting it: Example 1 kg of red-emitting oxide or yttrium oxysulfide phosphor is combined with 10 g of red cadmium sulfoselenide in a mortar grinder and without a pestle mixed until a color change can no longer be detected, namely visually or by remission measurement. Then the pestle is inserted, and 50 minutes the pigment rubbed off at a pressure of approx. 2,500 g. Then 1 ml of a 50 t Resin or latex emulsion containing solids with 5 ml of water and 5 ml of isopropyl alcohol diluted and in portions the pigmented phosphor with the mortar grinder running added. I) cr pressure on the 1> istili is increased to 150 kp. Nacll 10 The slightly damp phosphor is placed in a drying cabinet at approx. 1600C for minutes dried.

Examples 2 to 7 The procedure is the same as in Example 1.

Example 2 1 kg of blue-emitting zinc sulfide phosphor is with 30 g cobalt blue pigmented.

Example 3 1 kg of blue-emitting zinc sulfide phosphor is with 30 g of ultramine blue pigmented.

Example 4 1 kg of yttrium oxysulfide phosphor becomes red with 5 g of iron oxide pigmented.

Example 5 1 kg of green-emitting zinc cadmium sulfide phosphor becomes pigmented with 5 g chromium oxide, cobalt green etc.

Example 6 1 kg of manganese activated zinc orthosilicate phosphor becomes pigmented with 5 g green pigment.

Example 7 1 kg of manganese-activated potassium-magnesium-fluoride phosphor (P 19) is pigmented with 10 g of cadmium sulfoselenide-orange-red.

There was a 50% improvement in pigment adhesion to the phosphor.

Claims (8)

Process for applying color pigments to phosphor grains Claims: 1. A method for firmly adhering color pigments the surface of phosphor grains, treated with a resin emulsion as a fixing agent and drying, in particular at an elevated temperature, thereby g e -k e n n n z e i c This means that the pigments are rubbed onto the surface of the phosphor grains. 2. The method according to claim 1, characterized in that g e k e n n z e i c hn e t, that the pigments, and also the phosphors, only degloinerate when rubbed will. 3. The method according to any one of the preceding claims, characterized g e it is not noted that the pigment adhesion to the phosphor surface is additional by rubbing on a polymerizable resin emulsion, especially one that has already been prepolymerized Resin emulsion is reinforced. 4. The method according to claim 3, characterized in that g e k e n n -z e i c h n e t that the phosphor pigmented in this way at temperatures between 18 and dried at 250 ° C. 5. The method according to claim 4, characterized in that g e k e n n -z e i c h n e t that it is dried at 160 ° C. 6. The method according to any one of the preceding claims, characterized g e does not indicate that the phosphor is hydrophilic after pigmentation. 7. luminescent screen of a cathode ray tube, in particular an I: color picture tube, produced according to the process of one of claims 1 to 6, g e k e n n z e i c h -n e t through the application of pigmented phosphors. 8. Luminescent screen according to claim 7, g e k e n n z e i c h -n e t through an order of any phosphors known at the moment, which are with any Pigments are coated.