DE3000612A1 - HALOGENPHOSPHATE FLUORESCENT - Google Patents

Description

Henkel, Kern, Feiler & HärrzeK patent attorneys

Registered Representatives

before the

European Patent Office

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"I Jan. 19S0 Dr.F / rm

TOKYO SHIBAURA DENKI KABUSHIKI IiAISHA
Kawasaki / Japan

Halogen phosphate phosphor

3 0 0 2 9/0 8 B.

description

The invention relates to halophosphate phosphors, particularly halophosphate phosphors for use in fluorescent discharge lamps.

A halogen phosphate phosphor emits visible light when excited by UV light. The emission spectrum of the phosphor is widely distributed, whereby the color of the light can be controlled anywhere between warm white and bluish Yteiss leaves. Furthermore, the phosphor has a high emissivity and can be manufactured inexpensively. Hence the Halophosphate phosphors are widely used in fluorescent lamps.

A calcium halophosphate phosphor, which is a typical halophosphate phosphor, is usually obtained as follows: First, quantities of calcium hydrogen phosphate (CaHPO ^), calcium carbonate (CaCCU), calcium fluoride (CaF _2), ammonium chloride (NH ^ Cl), antimony trioxide (Sb ₂ CU) and manganese carbonate (MnCCU) mixed is fired and the mixture in an air atmosphere in a vessel equipped with a lid quartz crucible at a temperature of 1000 ° to 1200 ⁰ C. A calcium halophosphate phosphor with an apatite-type crystal structure activated by antimony and manganese is obtained. On the other hand, the firing can also take place under a nitrogen atmosphere in a quartz crucible without a lid. The phosphor obtained in each case is coarsely comminuted using a mortar and then finely pulverized in a ball mill. The phosphor powder thus obtained

030029/085?

is sieved by means of a sieve with a mesh size of about 0.147 mm, a ready-to-use phosphor powder receives. FIG. 1 shows a photomicrograph of a calcium halophosphate phosphor obtained as part of the measures described represent.

It can be seen from FIG. 1 that the phosphor particles are plate-shaped and have a rough surface. Such a phosphor leaves something to be desired with regard to its permeability for visible light. In addition, it should also be pointed out that the luminosity of the light emitted by the luminescent material decreases markedly during the burning in the production of a fluorescent lamp using the luminescent material of FIG. 1. As part of the production of a fluorescent lamp, a phosphor suspension is first prepared by adding phosphor particles, usually in an organic binder obtained by dissolving nitrocellulose in butyl acetate, or in an aqueous binder obtained by dissolving a water-soluble high molecular weight material in water was to be dispersed. The phosphor suspension obtained is then applied to the inner surface of a glass envelope, whereupon the whole thing is left to dry by itself or by heating. In this way, a fluorescent film is created. Thereafter, the phosphor film is fired at a temperature below the softening point of the glass envelope, usually at 500 ° to 60O ⁰ C, in order to decompose and remove the nitrocellulose or water-soluble high molecular weight material contained in the phosphor film. As already pointed out, the light intensity of the light emitted from the usual phosphor according to FIG. 1 deteriorates significantly during burning.

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The invention was based on the object of providing a halophosphate fluorescent substance to create that loses its light intensity only to a much lesser extent when burning and one has high output luminous intensity, i.e. luminous intensity of the light emitted from the phosphor before burning.

The invention thus provides a halophosphate phosphor made from halophosphate phosphor particles, which is characterized in that at least 80% by weight of the phosphor particles consist of spherical particles which ^{meet the equation R = R 1} <1.5R, where R and R ¹ stand for the smallest or largest particle diameter, are sufficient.

The invention is explained in more detail with reference to the drawings. Show in detail:

Fig. 1 is a photomicrograph of a common calcium halophosphate phosphor;

2 is a photomicrograph of a calcium halophosphate phosphor according to the invention; and

3 (A) to 3 (D) models of phosphor particles from which the definition according to the invention of the smallest and largest particle diameters R and R ¹ results.

The luminous intensity of the light produced by burning the raw materials and then pulverizing them the phosphor produced from the fired mass is hereinafter referred to as the "output light intensity" of the Phosphor defined. When making a fluo-

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A fluorescent lamp is applied to the inner surface of a glass envelope, whereupon the formed Coating is baked to produce a phosphor layer. The ratio of the luminous intensity of this Phosphor layer emitted light to the output light intensity of the phosphor is hereinafter defined as the "burning property" of the phosphor.

It has been shown that a halophosphate phosphor according to the invention a common phosphor 'both in output light intensity and in fluorescent burning property is superior. It is known that a 1% improvement in burning property results in a 1–6 increase of the total luminous flux emitted by a fluorescent lamp.

In a preferred manufacturing process for a halophosphate phosphor according to the invention, calcium hydrogen phosphate particles (CaHPO ^) are coated with a flux, for example antimony trichloride (SbCl,) or antimony oxychloride (SbAOcCl ₂ ), before firing to produce spherical halophosphate phosphor particles. In order for the phosphor to have an acceptable output light intensity and sufficient burning property, the phosphor particles should ^{contain a given amount of spherical particles which satisfy the relationship or equation R = R 1} <1.5R. Thus, the phosphor is given the desired good starting speed and focal property also reliable, this given amount of existing spherical particles should be at least 80 wt -.% Amount.

030Ü29 / 0852

From the photomicrograph (according to Figure 2) of a halophosphate phosphor according to the invention it can be seen that the Phosphor particles of spherical or spherical shape are. It has been shown that the phosphor shown in FIG. 2 corresponds to the phosphor shown in FIG visible light transmission and crystallinity is superior.

The following examples and comparative examples are intended to illustrate the invention in more detail.

example 1

2.4 g of antimony trichloride (SbCl,) are introduced into 0.5 l of pure water, whereupon the aqueous system is stirred for hydrolysis. The hydrolysis gives a suspension of antimony oxychloride (Sb ^ O ₅ Cl ₂ ). 200 g of calcium hydrogen phosphate (CaHPO ^) are then added to the suspension, whereupon the mixture is stirred for 20 minutes. After adding pure water, the mixture is filtered to separate the solid matter from the mixture. Now, the solid material is dried at a temperature of 80 ⁰ C and sieved with a sieve of a mesh size of 0.147 mm, coated with the flux antimony oxychloride Calciumhydrogenphosphatteilchen be obtained. The obtained particles are mixed with given amounts of calcium carbonate, calcium fluoride, ammonium chloride, antimony trioxide and manganese carbonate, and the mixture is then burned and pulverized in a conventional manner. A calcium halophosphate phosphor activated by antimony and manganese is obtained. Table I which follows later contains

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Information on the properties of the obtained phosphor, it has been found that the phosphor emits white light of a color temperature of 420O ⁰ K.

Example 2

In accordance with Example 1, a calcium halophosphate phosphor is used produced, however, in the preparation of a suspension of antimony oxychloride 3.2 g of antimony trichloride be entered in 0.5 l of pure water. Table I, which follows later, contains information on the properties of the phosphor obtained.

Example 5

In accordance with Example 1, a calcium halophosphate phosphor is used produced, but when preparing a suspension of antimony oxychloride 4.0 g of antimony trichloride be entered in 0.5 l of pure water. Table I, which follows later, contains information on the properties of the phosphor obtained.

Comparative example 1

A calcium halophosphate phosphor activated by antimony and manganese is produced in the same way as in Example 1, but the calcium halophosphate particles used during firing are not coated with the antimony oxychloride flux. Table I, which follows later, contains information on the properties of the phosphor obtained. It has been shown that the phosphor emits white light with a color temperature of 4200 ^° K.

BATH

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Comparative example 2

In accordance with Example 1, a calcium halophosphate phosphor is used produced, but in the preparation of a suspension of antimony oxychloride 0.8 g of antimony trichloride in 0.5 l of pure water. The following Table I contains information on the properties of the phosphor obtained.

Comparative example 3

In accordance with Example 1, a calcium halophosphate phosphor is used produced, but in the preparation of a suspension of antimony oxychloride 1.6 g of antimony trichloride be entered in 0.5 l of pure water. Table I, which follows later, contains information on the properties of the phosphor obtained.

1 Tabel I. Brandy
societies
in % Particle
shape IV / R 2 Starting
light intensity
in % 92.0 plates
shaped Comparison case
game 3 100.0 92.0 spherical 1.5-2.0 Il 100.5 92.2 Il 1.4-1.8 It 101.2 94.0 ti 1.2-1.5 example 1 102.3 96.0 Il 1.1-1.4 ι. 2 103.0 96.0 Il 1.0-1.3 π 3 103.2

030029/0852

BAD'ÖRiÖINAL

- tr -

In the ratio R ¹ / R in Table I, R 'stands for the largest diameter of the calcium halophosphate phosphor particle, R for the smallest diameter of the phosphor particle which passes through the center of the largest diameter R ¹ . FIGS. 3 (A) to 3 (D) show models of spherical fluorescent particles in which R ¹ and R are drawn. The values for the ratio R ¹ / R in Table I correspond to the result of actual measurements on 50 phosphor particles of Examples 1 to 3 and Comparative Examples 2 and 3.

Table I shows that the phosphors of Examples to 3 to the phosphors of Comparative Examples 1 to are superior both in the output light intensity and in the fluorescent burning property. The fluorescent particles of Comparative Example 1 are plate-shaped because the calcium hydrogen phosphate particles are not fluxed with the antimony oxychloride are coated.

The following table II contains information on the output light intensity and the burning property of phosphor mixtures made from the phosphors of Example 1 and Comparative Example 2. The following table III contains information on the initial light intensity and burning property of phosphor mixtures from the phosphors of Example 1 and Comparative Example 1.

03CQ.2 9/08 5 2 BAD ORIGINAL

- y? R -

Tabel Tabel II III Brandy
societies
in % Fluorescent
of the case
play 1 in
Geyr .-% Fluorescent des
Comparison case
play 2 in
Wt% Fluorescent des
Comparison case
play 1 in Starting
light intensity
in % Starting
light intensity
in % 94.0 95 5 5 102.3 102.3 94.0 90 10 10 102.3 102.2 94.0 85 15th 15th 102.2 102.0 93.8 80 20th 20th 102.2 102.0 93.8 75 25th 25th 102.1 101.5 92.3 70 30th 30th 101.5 101.5 92.2 65 35 35 101.3 101.0 92, 2 60 40 40 101.3 100.5 Brandy
societies
in % Fluorescent
of the case
play 1 in
Weight .-? O 94.0 95 94.0 90 93.8 85 93.8 80 93.0 75 92.3 70 92.0 65 92.0 60

Tables II and III show that phosphors with at least 80% by weight of spherical phosphor particles, which ^{correspond to the equation R = R 1} < 1.5R, have sufficient output light intensity and burning properties

π π

2 9 / 085-

BATH ORIGINAL

The halophosphate phosphors according to the invention are not limited to calcium halophosphate phosphors, Rather, they can also be halophosphate phosphors, some of which are calcium is replaced by strontium, magnesium, barium, zinc or cesium.

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Claims (1)

Claim Halophosphate phosphor consists of halophosphate phosphor particles of which at least 80% by weight consist of spherical phosphor particles sufficient for the relationship R = R '<1.5R (where R and R ¹ indicate the smallest and largest diameter of the phosphor particles, respectively). 0 2 U υ? Π / η: