JPH0480284A - Green-emitting phosphor and fluorescent lamp using the same - Google Patents

Abstract

PURPOSE:To provide a green-emitting phosphor which is high in luminance and dispersibility and gives a uniform phosphor coating by coating the surfaces of perticles of a Tb-activated green-emitting phosphor having a specific composition with a given amount of a water-soluble polyolefin glycol. CONSTITUTION:The surface of particles of a terbium-activated green emitting phosphor represented by formula I or II (wherein R<1> is Y, La or Gd; a>0; b>0; 0.1<=a+b<=0.7; e>=0; f>=0; g>0; 0.8<=e+f+g<=1.3; x>=0; y>0; 5X10<-6=z<=6X10<-3>; 0.8<=x+y+z<=1.3) are coated with 0.005 - 0.5wt.% water-soluble polyolefin glycol (e.g. polypropylene glycol) based on 100wt.% particles of the phosphor. The resulting particles have good dispersibility in slurries and hence are capable of forming a uniform phosphor coating.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Application Field) The present invention relates to a green-emitting phosphor, and particularly to a green-emitting phosphor suitable for use in a pressure wavelength range emitting fluorescent lamp, and a green-emitting phosphor using the same. Regarding the fluorescent lamp used.

(Prior art) Pressure wavelength range fluorescent lamps that simultaneously satisfy high efficiency and high color rendering properties are rapidly becoming popular as fluorescent lamps for general lighting, and have become the mainstream light source for home lighting. .

This type of fluorescent lamp uses blue, green, and red emitting phosphors that have a relatively narrow emission spectral distribution.

Conventionally, as a green-emitting rare earth aluminate/silicic acid/phosphate phosphor activated with cerium and terbium, [(R
e, Tb, Ce) 2 03 ・Al1 03SI
02 R205] (see Japanese Patent Publication No. IO-9543) is known.

In addition, as a rare earth silicic acid/boric acid/phosphate phosphor, [(
Re, Tb, Ce) 2 03 5i02
R205B203 (see Japanese Patent Publication No. 44792), and other rare earth orthophosphate phosphors include C(Re, Tb, Ce) PO4 (Special Publication No. 44792).
No. 9-435 (see Publication No. 11) is known.

In preparing a water-soluble phosphor suspension (slurry), it is known to use polyethylene oxide as a water-soluble binder (see Japanese Patent Laid-Open No. 129286/1986).

In such a pressure wavelength range fluorescent lamp, the proportion of the green light emitting phosphor in the total luminous flux (emission output) is very high, and therefore the characteristics of the green light emitting phosphor are different from the pressure wavelength range fluorescent lamp. It greatly influences the performance of

Incidentally, the fluorescent film of a pressure wavelength range fluorescent lamp is formed from a phosphor suspension (phosphor slurry) that is a mixture of blue, green, and red colors. Therefore, the physical properties of each color of phosphor affect the properties of the slurry. For example, when comparing the specific gravity of each color of phosphor, blue-emitting phosphor usually has a specific gravity of around 3.8 to 4.1, while red-emitting phosphor has a specific gravity of around 3.8 to 4.1. is around 5.1, while that of green-emitting phosphor is around 5.3.
It is the largest before and after.

Therefore, in a phosphor slurry of a mixture of three or more types of phosphors used in fluorescent lamps, the green-emitting phosphor settles and falls relatively faster than other phosphors, resulting in uneven distribution of the three colors. This poses a problem in that the quality of the fluorescent film deteriorates.

(Problem to be Solved by the Invention) As mentioned above, when using a three-color mixed slurry in a pressure wavelength range fluorescent lamp, it is difficult to use a rare earth aluminate/silicate/phosphate phosphor, which is a conventional green-emitting phosphor. or,
There has been a problem in that the dispersibility of rare earth silicic acid/boric acid/phosphate phosphors or rare earth orthophosphate phosphors is worse than that of other colors.

For this reason, the green component aggregates in the slurry and settles faster than other phosphors, disrupting the balance of the three colors on the phosphor screen and hindering the quality improvement of the phosphor film of the fluorescent lamp.

Furthermore, since the green component has the largest contribution to the white color of the lamp, the instability of the green component directly affects the quality of the fluorescent lamp.

In this way, the dispersion and stability of the green component greatly affect the quality of the phosphor film (phosphor screen). Therefore, the dispersibility of the green-emitting phosphor is increased, and the sedimentation rate in the slurry is controlled to be lower than that of the other colors of phosphor. The challenge is to control it to the same degree as the body.

The present invention has been made to solve these problems, and includes a green-emitting phosphor that has good dispersibility in a slurry and can form an even phosphor screen, and a green-emitting phosphor that can be used to make a fluorescent screen. The purpose is to provide a fluorescent lamp with improved film quality.

[Configuration of the Invention (Means for Solving the Problem) The green light-emitting phosphor of the present invention has the general formula % (wherein R1 represents at least one element selected from Y, La5Gd, a, b and e, f.

g is a number that satisfies the following formula.

a>0, b>o, 0,1≦a+b≦0.7, e≧0, f
≧o, g>o, 0.8≦B+f+g≦1.30°); Indicates at least one element selected from Cd, aSb and X5ys2
is a number that satisfies the following formula.

a>0, b>o, 0.1≦a+b≦0.7, X≧0, y
〉0.5. OX 10-' ≦z ≦6. OX 10-
"0.8≦x+y+z≦1.30゜) 0.005% by weight or more of water-soluble polyolefin glycol per 100% by weight of the particles of the terbium-activated green light-emitting phosphor expressed as It is characterized in that the surface of the phosphor is coated in an amount of .5% by weight or less.

Further, the fluorescent lamp of the present invention is characterized in that it includes a fluorescent film formed using the green-emitting phosphor described above.

In the present invention, the polyolefin glycol coating the surface of the phosphor is preferably soluble in water, and further soluble in both water and alcohols.

This is because organic solvents may be used in the fluorescent film forming process depending on the equipment, so if it is soluble in both water and alcohol, it can be used in a variety of fluorescent film forming systems. Because it will be.

In particular, polyethylene glycol is suitable as a coating layer because it is inexpensive and chemically stable.

In the present invention, the concentration of the polyolefin glycol coated on the surface of the green-emitting phosphor represented by the above formula (r) or (II) is 0% based on 100% by weight of the phosphor particles.
．． 0.05% by weight to 0.5% by weight.

If the coating amount is less than 0.005% by weight, the effect of polyolefin glycol cannot be obtained sufficiently, and the phosphor film (phosphor screen)
quality will not be improved.

On the other hand, if it exceeds 0.5% by weight, the luminous output as a green-emitting phosphor will be significantly reduced.

As mentioned above, the matrix of the green light-emitting phosphor of this invention includes rare earth aluminate/silicic acid/phosphate, rare earth silicic acid/phosphate, rare earth aluminic acid/phosphate, rare earth orthophosphate, rare earth silicic acid/phosphate, etc. Boric acid and phosphates, as well as rare earth boric acids and phosphates, are used, and the action and effects of this invention are not influenced by the type of parent material.

(Function) The surface of the green-emitting phosphor of this invention is coated with polyolefin glycol, which improves its dispersibility in slurry, prevents aggregation of phosphor particles, and reduces the speed of sedimentation. Can be suppressed.

Therefore, only the green component does not settle first and the color balance is not disturbed, and a uniform fluorescent film is formed.

This allows for high luminous output and fluorescent film (phosphor screen).
It is possible to obtain a fluorescent lamp of good quality.

(Example) Next, embodiments of the invention will be described.

Example 1 Polyethylene glycol (molecular weight 40
Add 0.12f of 0) and stir the solution for a sufficient amount of time to completely dissolve the polyethylene glycol.

Next, a rare earth aluminate-silicic acid-phosphate green-emitting phosphor activated with terbium [(Lag4oCeo, 25T
bo, 15) 2 03 0.003AI2 03
Add 200 g of 0.0005SiOz·1.003P2 05 ] and stir thoroughly.

Thereafter, a suspension containing polyethylene glycol and a green-emitting phosphor is filtered by a suction filtration method, and the filter cake is dried at a temperature of about 100°C.

The surface of the thus obtained phosphor particles was 0.05% by weight.
It is uniformly covered with a polyethylene glycol film.

Subsequently, 100 g of this green-emitting phosphor was added to a nitrocellulose solution with 4% by weight of trocellulose (NO), 100cc of butyl acetate (98% by weight), and 10c of butyl acetate.
c. Prepare a phosphor suspension (phosphor slurry) by adding 1 g of calcium pyrophosphate powder to a solution prepared in advance and thoroughly stirred.

Using this phosphor slurry, the slurry is applied to the inner surface of a glass bulb for PL40SS/37 to form a phosphor film.

After drying, the fluorescent film was observed with the naked eye to evaluate the quality of the film. In evaluating the film quality, 10 points were given to films with no agglomerated parts (bubbles) and those with smooth surfaces, and points were subtracted according to the degree of agglomerated parts and the degree of surface unevenness, and the results were quantified.

Furthermore, using a glass bulb with a fluorescent film formed thereon, a fluorescent lamp PL40SS as shown in FIG.
-G/37 was produced, and the initial luminescence output was measured and evaluated.

In FIG. 1, the fluorescent lamp has a fluorescent film 2 adhered to the inner surface of a glass bulb 1, and is further filled with a discharge gas at a predetermined pressure.

Furthermore, electrodes 3 are attached to both ends of the glass bulb 1, and by applying a predetermined voltage to the electrodes 3, the fluorescent film 2 emits light due to the excitation source.

On the other hand, as a comparative product, the same green-emitting phosphor (a rare earth aluminate/silicic acid/phosphate green-emitting phosphor activated with terbium) was used without the polyethylene glycol coating.
A similar fluorescent lamp was manufactured and its characteristics were measured under the same conditions as in the example.

As a result, the film quality of the conventional phosphor was 7.0, whereas the film quality of the phosphor of this example was 9.5.

Further, the initial light emission output is expressed as a relative value when the initial light emission output of a conventional phosphor is taken as 100%, and the fluorescent lamp of this example had a value of 99.5%, and no significant difference was observed.

These results are summarized in Table 1.

Example 2 Polypropylene glycol (trimer) in 600cc of pure water
Add 0.48 g of polypropylene glycol and stir the solution for a sufficient amount of time to completely dissolve the polypropylene glycol.

Next, a rare earth silicic acid/boric acid/phosphate green emitting phosphor activated with terbium [(Lao4oCeo, 4sTbol
s)203・0.001Si02・0.98
8P2 05 0.0005B203] 2QrJ
g and stir thoroughly.

Thereafter, a suspension obtained by mixing these is filtered by a suction filtration method, and the filter cake is dried at a temperature of about 100°C.

The phosphor particles thus obtained have a surface of 0.
It is uniformly covered with a coating of 20% by weight polypropylene glycol.

A fluorescent lamp was produced using this green-emitting phosphor in the same manner as in Example 1, and its characteristics were measured and evaluated under the same conditions.

These results are shown in Table 1.

Examples 3 to 12 As shown in Table 1, the coating concentration of the green-emitting phosphor and the polyolefin glycol coating its surface was varied,
A green-emitting phosphor was prepared in the same manner as in Example 1.

Furthermore, a fluorescent lamp was manufactured using the obtained green-emitting phosphor, and its characteristics were evaluated.

These results are summarized in Table 1.

(Left below) As is clear from these results, the fluorescent lamp using the green-emitting phosphor according to this example maintains the initial light output almost the same as the conventional one, and the film quality of the phosphor film is significantly improved. We were able to achieve a significant improvement in quality.

[Effects of the Invention] As described above, according to the present invention, a green light-emitting phosphor with high brightness and high dispersion can be obtained, and a uniform phosphor film with good balance of three colors can be formed. Therefore, it is extremely useful as a green-emitting phosphor for fluorescent lamps.
This will greatly contribute to improving the quality of fluorescent lamps.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway view of a fluorescent lamp according to an embodiment of the present invention. 1... Glass bulb, 2... Fluorescent film, 3... Electrode. Applicant Toshiba Corporation Toshiba Electronic Device Engineering Corporation

Claims (4)

[Claims] (1) General formula (R^1_1_-_a_-_bTb_aCe_b)_2
O_3・eAl_2O_3・fSiO_2・gP_2O
_5...(I) (In the formula, R^1 represents at least one element selected from Y, La, and Gd, and a, b, e, f, and g are numbers that satisfy the following formula. Yes. a>0, b>0, 0.1≦a+b≦0.7, e≧0, f
≧0, g>0, 0.8≦e+f+g≦1.30. ) or the general formula (R^1_1_-_a_-_bTb_aCe_b)_2
O_3・xSiO_2・yP_2O_5・zB_2O_
3...(II) (In the formula, R^1 represents at least one element selected from Y, La, and Gd, and a, b, and x
, y, and z are numbers that satisfy the following formula. a>0, b>0, 0.1≦a+b≦0.7, x≧0, y
>0, 5.0×10^-^6≦z≦6.0×10^-^
3, 0.8≦x+y+z≦1.30. ) Water-soluble polyolefin glycol is added in an amount of 0.005% by weight or more and 0.5% by weight or less based on 100% by weight of the particles of the terbium-activated green light-emitting phosphor represented by A green-emitting phosphor characterized by coating the surface of the phosphor. (2) The green-emitting phosphor according to claim 1, wherein the polyolefin glycol is soluble in both water and alcohols. (3) The green light-emitting phosphor according to claim 1, wherein the polyolefin glycol is polyethylene glycol. (4) A fluorescent lamp comprising a fluorescent film formed using the green-emitting phosphor according to any one of claims 1 to 3.