JPS6164784A - Manufacturing method of pigmented phosphor - Google Patents

Abstract

PURPOSE:To produce a pigment-coated fluorescent material which has strong pigment adhesion and scarcely flocculates, by grinding particles of a fluorescent material in a solvent, and adding pigment particles and a binder to bring into contact therewith. CONSTITUTION:Particles of a fluorescent material such as ZnS:Ag or Y2O2S:Eu, of an average particle diameter of 3-12mum, are dispersed in a solvent (e.g., water) and are ground in a mill such as a ball mill or a pearl mill to render the surface mechanochemically active. Particles of a pigment (e.g., cadmium sulfoselenide) and a binder (e.g., gelatin or gum arabic) are added to this suspen sion, and this mixture is heated to an appropriate temperature to allow particles of the pigment to be adsorbed or fixed on the surface of particles of the fluores cent material by means of the binder. The fluorescent material-pigment-binder system is then separated by filtration, is dried, and is ground.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a method for manufacturing a pigmented phosphor used for a fluorescent film of a color cathode ray tube or the like.

"Prior Art" Phosphors (pigmented phosphors) in which blue pigment particles, green pigment particles, and red pigment particles are adhered to the particle surfaces of blue-emitting phosphors, green-emitting phosphors, and red-emitting phosphors, respectively. The filter effect of each pigment particle cuts part of the visible range of the emission spectrum, making the emission color clearer, and the absorption effect of external light due to the coloring of the fluorescent film reduces reflected light. This dramatically improves the contrast of images (Japanese Patent Application Laid-Open No. 50-56146), so it is widely used as a fluorescent film in cathode ray tubes for color television sets and computer terminal displays. ing.

Conventional methods for producing pigmented phosphors include, for example, dispersing the phosphor and/or pigment in an aqueous solution containing latex or breaking the emulsion by changing the temperature or adding a specific metal salt. A method in which latex is adsorbed onto phosphors and pigments, then separated from an aqueous system, dried, and pulverized (
JP-A No. 52-109488), method for attaching pigment to phosphor using gelatin and gum arabic coacelvage (IWF Publication No. 54-3677), 5IO2
, a method using an inorganic salt such as At203° phosphate as a binder (Japanese Unexamined Patent Publication No. 54-28783-28785), etc.
A method of adhering a phosphor and a pigment using an organic or inorganic binder has been put to practical use.

By the way, in pigmented phosphors, it is functionally important that the pigment particles are uniformly and firmly attached to the surface of the phosphor particles, but in general, pigmented phosphors obtained by the above-mentioned conventional manufacturing method When attaching a phosphor and a pigment via a binder, the pigment and binder may not have sufficient affinity for the phosphor, and the phosphor particle size may be 10 to 100 times larger than the pigment particle size. However, since the number of pigment particles is much larger than the number of phosphor particles, aggregation of pigment particles occurs in the binder, and the uniformity of pigment particles on the surface of the phosphor particles is lost. However, if K requires a large amount of pigment particles in order to obtain a certain specific reflectance, it will cause a decrease in brightness, and at the same time, it will not be possible to obtain sufficient adhesion strength of pigment particles, and in order to increase the pigment adhesion force. However, when the amount of binder is increased, phosphor particles tend to aggregate with each other, which is undesirable. In order to solve this problem, it has been possible to significantly improve the uniformity of pigment particles on the surface of the phosphor by considering the selection of the binder and the manufacturing method. However, especially in the case of phosphors with small particle diameters of about 3 to 7 μm, which are used in cathode ray tubes for high-definition displays, reducing the amount by 4 inches, for example, can prevent agglomeration of pigment particles and phosphor particles. However, when it is necessary to attach a large amount of pigment to obtain a certain specific reflectance, it is necessary to obtain sufficient pigment adhesion force with a limited amount of binder that does not lead to aggregation of phosphors or pigment particles. was still difficult.

"Problems to be Solved by the Invention" The present invention has been made in view of the above-mentioned circumstances.It is a pigmented phosphor that has stronger pigment adhesion and is less prone to agglomeration than conventional manufacturing methods. This was done for the purpose of providing a manufacturing method.

As a result of various studies on processing methods for phosphor particles and pigment particles, the present inventors have found that the phosphor particles or the phosphor particles and pigment particles are treated with iIJ before being mixed with a binder.
Song found that the above object could be achieved by grinding the surfaces of phosphor particles or phosphor particles and pigment particles in advance and mechanochemically activating the surfaces, leading to the completion of the present invention. .

``Means for Solving the Problems'' That is, the present invention includes a step of bringing phosphor particles and pigment particles into contact with a binder in a solvent and adsorbing or fixing the pigment particles to the surface of the phosphor particles via the binder. The method for producing a pigmented phosphor is characterized in that the phosphor particles are ground in advance in a solvent before adding a binder.

The method for attaching pigment particles of the present invention will be described in detail below.

In the method for producing the pigmented phosphor of the present invention, first, the phosphor particles dispersed in a solvent are thoroughly milled using a mill such as a mail mill or a 9-lumin mill to coat the surface of the phosphor particles. Grind to make the surface mechanochemically active. Next, a powdered pigment or a suspension of pigment particles separately dispersed in a solvent is added to this suspension together with a predetermined amount of binder, and then an appropriate amount is added according to the type of binder by a conventionally known method. Apply chemical treatment. For example, when gelatin and gum arabic are used as binders, a predetermined amount of pigment, gelatin, and gum arabic are added to the phosphor suspension that has been milled, and then heated to an appropriate temperature. is adjusted to a value that causes the gelatin-gum arabic core cell purge to occur on the acidic side. In addition, when latex is used as a binder, the pigment and latex are added to the phosphor suspension after the phosphor particles have been triturated, and then the acidity of the phosphor suspension is adjusted to the acidic side. Add salt. After the pigment particles are adsorbed or fixed on the surface of the phosphor particles through a binder through such chemical treatment, the phosphor-pigment-binder system is separated from the solvent by an operation such as filtration, and then dried and pulverized. By this method, a pigmented phosphor having pigment particles attached to the surface can be obtained.

Incidentally, the grinding treatment of the phosphor particles may be performed on the phosphor alone as described above, but the phosphor particles and the pigment particles may be mixed in advance in a solvent, and this mixed suspension may be It is more effective and efficient to apply a predetermined chemical treatment after grinding to make the surfaces of the phosphor particles and pigment particles mechanochemically active, and then adding a binder thereto. Furthermore, when grinding phosphor particles in a solvent, pigment particles can be attached to the phosphor particles even if a binder is added in advance; It is better to grind the phosphor particles (i.e.,
It is better to grind the phosphor particles in advance without bringing the pine paste and the phosphor particles into contact with each other, so that the pigment particles can be applied uniformly to the surface of the phosphor particles with stronger adhesion. It can be attached.

The method for producing a pigmented phosphor of the present invention is a europium-activated oxysulfide, thorium phosphor (Y2O2S: Eu).

Europium-activated fermented yttrium phosphor (Y2O2:
gll), europium-activated vanadine, thorium phosphor (Y'vo4:Eu), silver-activated zinc sulfide phosphor (ZnS:Ag), silver and aluminum, 6nium-activated zinc sulfide phosphor ( Zn8: Ag+At), steel and aluminum activated zinc sulfide phosphor (ZnS: Cu, A
t) It goes without saying that it is mainly applied to phosphors for color television labels, such as I gold, copper and aluminum activated zinc sulfide phosphors (Zn8: Cu, Au + phosphors), but it is not always necessary. Needless to say, the present invention is not limited to this, and may be applied to any other commonly used fluorescent materials. However, Zn8:Ag + ZnS
:Ag, Ni#ZnS:Cu, AtIZnS:
It is more preferable to use a sulfide such as Cu*AuHAl-, since it is possible to obtain a pigmented phosphor with particularly high pigment adhesion and less aggregation. The phosphors used in the manufacturing method of the present invention have an average particle diameter of 3 to 12 μm.
However, especially when attaching pigment particles to a small particle phosphor of 3 to 7 microns, the pigment adhesion force can be improved compared to conventional methods.

Furthermore, there are no particular restrictions on the pigment particle binding used in the production method of the present invention, and for example, cadmium selenide (Cd)
S, x, S@ri, 0 (X<1) l valve handle (Fe1
2. ).

Red pigment particles such as suboxide steel (Cu zO), orange or yellow pigment particles such as basic lead chromate (PbCr04), cadmium yellow (CdS), chromium green (P bcro4 + F@a (F s (CN) b)
) a ・nHzo ) , :' Parto Green (Coo-n
Green pigment particles 1 ultramarine (3Na-At-81
02-Na2S2).

Dark blue (F@4[Fe(CN)6]s・nH20), :'
Any pigment can be used, such as blue pigment particles such as Baltic Blue (Coo-nAt203), black pigment particles such as manganese 7-elite (mainly used in monochrome cathode ray tube phosphors), and the like.

Furthermore, organic binders used in the production method of the present invention include acrylic resins, vinyl resins, phenol resins, and epoxy resins.

Polyurethane resins, urea resins, /lyester resins, cellulose resins, etc. may be dissolved in an appropriate solvent such as doluol ethyl acetate, methyl acetate, water, etc., and adjusted to an appropriate viscosity. used from Also used is an emulsion resin obtained by emulsion polymerization of the above resins. Other than that, potash water 7! /2s.

Inorganic materials such as sodium water glass and ethyl silicate may be used, as well as rosin, casein, and glue.

Natural synthetics such as gelatin can also be used as binders.

FIG. 1 shows the conditions for grinding the phosphor particles before adding a binder to the pigmented phosphor produced by the production method of the present invention (i.e., the conditions for grinding the phosphor).
This is an example of the relationship between the degree of aggregation of the obtained phosphor with a face finger and the pigment adhesion force when changing the phosphor. This figure shows a pigmented phosphor to which a cobalt blue pigment having an average particle diameter of 0.2 μm is attached. In FIG. 1, the pigment adhesion force on the vertical axis represents the obtained pigmented phosphor 31't O, 1 wt% water glass aqueous solution 3
Place it in a test tube with 0m, shake it by hand for 30 seconds, then set it up again. After the phosphor has settled sufficiently, separate the supernatant liquid containing floating release pigment and measure the transmittance of the liquid using a colorimeter. was measured and its absolute value was expressed as the finger adhesion of CIIA material adhesion.

The degree of agglomeration on the horizontal axis is the average particle diameter of the pigmented phosphor obtained and the single particle diameter of the phosphor before the pigment is attached (the average value of the particle diameters measured from electron micrographs). (pigmented phosphor average particle diameter/single particle diameter) When a phosphor film is prepared using a large amount of agglomeration of the cathode ray tube particles, the degree of filling of the phosphor particles is poor (the texture of the film is rough), and as a result, the brightness of the cathode ray tube is reduced. In Fig. 1, straight lines a, b, e, and d are respectively drawn for 2.5 hours when glass is used, 1:16 hours when glass gel is used, and 2.5 hours when alumina gel is used. This is the case when an aqueous suspension of phosphor particles is milled in a sol mill before adding the binder for 16 hours using a gall, and the straight line f is when the phosphor particles are milled in a mail mill before adding the binder. This shows the case where no grinding treatment was performed.

As is clear from Fig. 1, the higher the hardness of the sol used for mail milling (c, d), and the longer the time for mail milling (i.e., the stronger the grinding conditions) (b, d) When the degree of agglomeration is constant, the pigment adhesion is strong, and when the pigment adhesion is constant, the degree of agglomeration is low, and the phosphor particles are not subjected to a grinding process. It can be seen that the pigment adhesion is superior to that of the obtained pigmented phosphor and there is less aggregation. Note that the stronger the grinding conditions for the phosphor, the better the pigment adhesion will be, but on the other hand, the phosphor crystal will be damaged, resulting in a decrease in brightness, so the grinding conditions should be adjusted with this in mind. is determined. In order to grind the surface of the phosphor crystal with as little damage as possible, it is preferable to use glass, alumina, zircon, agate, etc. as the material for the mail.

Figure 2 shows the relationship between the zeta potential of a suspension obtained by milling a Zn8:Ag phosphor in a solvent and the milling time and the milling time. This is the case when pure water and acetic acid at pH 4 are used as
The zeta potential at pH 4) is shown.

As is clear from Figure 2, the value of zeta potential differs depending on the solvent used, but in all cases, the zeta potential increases as the milling time increases, such as acrylic emulsion, gelatin-gum arabic microcapsules, etc. The difference between the zeta potential of the binder and the zeta potential of the binder increases. It is not clear why grinding the phosphor in advance increases the pigment adhesion and allows the pigment to adhere uniformly to the surface of the phosphor. becomes mechanochemically active, the schizeta potential increases, and the difference in zeta potential with the binder increases, which increases the affinity between the phosphor and the binder.As a result, the binder entrains the fine particles of pigment onto the phosphor surface. (If the zeta potential difference is small, the affinity between the phosphor and the binder will be poor, and the binder will become an aggregate containing only the binder or only the pigment, and will not adhere to the phosphor.) This is probably due to the fact that the fluorophores are scattered among the fluorophores.

In addition, when using a phosphor other than ZnS:Ag, when using a pigment other than cobalt blue, and when using a binder other than gelatin and arabic 9, the phosphor that has been subjected to a grinding process in advance may be used. It has been confirmed that when a pigment is attached to this material via a binder using a phosphor with a pigment attached thereto via a binder, a pigmented phosphor with stronger pigment adhesion and less agglomeration can be obtained than that obtained using conventional manufacturing methods. Ta.

"Example" Examples of the present invention are shown below, but the present invention is not limited thereto. ZnS:At phosphor 20
01 and an aqueous dispersion of cobalt blue blue pigment (3I in terms of pigment solid content) that had been sufficiently crushed in advance in a volume of 500-
After adding 20 tons of glass beads with a diameter of 5 φ and 100 d of water, the mixture was milled in a gold mill for 2.5 hours. Next, after heating the suspension from which the glass peas were separated to 40°C, a gelatin solution (solid content 0.36% by weight) and an Arabian gum solution (solid content 0.30% by weight) were added and heated with acetic acid. ,j5 pH4,1
The gelatin was made insoluble by adding glutaraldehyde, which was then oven-dried and crushed to form a ZnS:Ag phosphor with a cobalt blue pigment attached via the gelatin and the araco9m. Pigmented phosphor (1)] was obtained.

For comparison, a pigmented phosphor (r-1) was produced in the same manner as above except that the ZnS:Ag phosphor was not ball milled.

In addition, using ZnS:Ag phosphor, cobalt blue blue pigment, gelatin and arabic plum, the weight ratio of gelatin to arabic plum in the non-ingu, milling time and type of mill during milling were as shown in the table below. Pigmented phosphors (2) to (5) and (r-2) to (r-5) were prepared in the same manner as pigmented phosphors (1) and (r-1) except for changing the procedure.
was manufactured.

Furthermore, using the milling time and the type of goal during milling as shown in the table below, an acrylic resin emulsion with a solid content of 0.25 wt. ni, m, LC-4
0) was added to adjust - to 4.5, and the pigmented phosphors (1) to (5) and (r
Pigmented phosphor (6) in the same manner as -1) to (r-5).

(7), (r-6) and (r-7) were produced.

The results of measuring the pigment adhesion force and degree of aggregation of each of the pigmented phosphors thus obtained are shown in the table below.

By performing this milling process, the degree of agglomeration of the pigmented phosphor obtained is almost constant compared to the pigmented phosphor obtained by the conventional manufacturing method that does not involve milling. In comparison, the pigment adhesion was significantly increased. Furthermore, when comparing pigments with almost the same pigment adhesion strength, the degree of agglomeration was significantly lower.

"Effects of the Invention" According to the manufacturing method of the present invention, the surface of the phosphor is pre-milled to make the surface mechanochemically active, thereby increasing the affinity between the phosphor and the binder compared to conventional methods. It is possible to strongly and relatively uniformly adhere the pigment particles to the surface of the phosphor particles, and to produce a pigmented phosphor with little agglomeration.

[Brief explanation of drawings]

Figure 1 is a graph showing the relationship between pigment adhesion and agglomeration degree in the pigmented phosphor produced by the production method of the present invention, and Figure 2 is a graph showing the relationship between the zeta potential of the phosphor suspension and milling time. It is a graph showing the relationship between. Figure 1) Suspicious shoulders

Claims (6)

[Claims] (1) A method for producing a pigmented phosphor comprising a step of bringing the phosphor particles and pigment particles into contact with a binder in a solvent and adsorbing or fixing the pigment particles to the surface of the phosphor particles via the binder. 1. A method for producing a pigmented phosphor, which comprises grinding phosphor particles in a solvent before adding the phosphor. (2) The method for producing a pigmented phosphor according to claim 1, wherein the grinding treatment is performed by ball milling. (3) A method for producing a pigmented phosphor according to claim 1 or 2, characterized in that the phosphor particles are subjected to a grinding treatment together with the pigment particles. (4) The method for producing a pigmented phosphor according to any one of claims 1, 2 and 3, wherein the solvent is water. (5) The average particle diameter of the phosphor particles is 3 μ to 7 μ.
A method for producing a pigmented phosphor according to any one of claims 1, 2, 3, and 4, characterized in that: (6) Any one of claims 1, 2, 3, 4, and 5, characterized in that the phosphor particles are sulfide-based phosphors. A method for producing a pigmented phosphor according to .