JP5989775B2 - Phosphor, method for manufacturing the same, and light emitting device using the same - Google Patents

Description

  Embodiments of the present invention relate to a phosphor used in a light-emitting device such as an LED lamp, in particular, a phosphor that emits green light to yellow light, and a light-emitting device using the same.

  In recent years, technologies corresponding to environmental protection such as lead-free have expanded worldwide, and accordingly, a light source (lamp) for illumination is also a light emitting diode that emits white light from a fluorescent lamp containing Hg ( The LED (Light Emitting Diode) lamp is shifting. In general lighting applications, white LED lamps with high color rendering properties and long life are required, and white LED lamps that provide high efficiency and wide color reproducibility are used as backlights for liquid crystal display devices (LCD). It is requested.

  In order to meet these requirements, instead of white LED lamps that combine blue LED chips and yellow phosphors (YAG phosphors), blue LED chips and silicate phosphors that emit green to yellow light. And white LED lamps that combine a nitride phosphor that emits red light.

However, this type of white LED lamp is superior in efficiency, color rendering, and color reproducibility compared to an LED lamp combining a blue light emitting LED chip and a yellow phosphor (YAG phosphor), but it has excellent heat resistance and There was a problem that weather resistance such as moisture resistance was poor. Among these, (Sr, Ba, Ca) ₂ SiO ₄ : Eu phosphors known as silicate phosphors emitting green to yellow light in combination with blue light emitting LEDs are not sufficient in terms of weather resistance, The appearance of a silicate phosphor that emits green to yellow light with better weather resistance has been desired.

International Publication No. 2008/096545

  The present invention has been made to solve the technical problems as described above, and has an object to provide a phosphor for a light-emitting device that has high color rendering and color reproducibility, and is particularly excellent in efficiency and weather resistance. Yes. Another object of the present invention is to provide a light-emitting device such as a white LED lamp which is excellent in efficiency and weather resistance and has high color rendering properties and color reproducibility by using such a phosphor.

The phosphor according to the present embodiment includes europium (Eu) substantially represented by (Sr, Ba, Mg) ₂ SiO ₄ : Eu, Mn, strontium (Sr) activated by manganese (Mn), barium ( Ba), alkaline earth magnesium silicate phosphor particles, and magnesium pyrophosphate (Mg ₂ P ₂ O ₇ ) or magnesium pyrophosphate on the phosphor particle surface, calcium pyrophosphate (Ca ₂ P ₂ O ₇ ) , pyrolin Phosphors uniformly coated with a mixture of at least one of barium acid (Ba ₂ P ₂ O ₇ ) and strontium pyrophosphate (Sr ₂ P ₂ O ₇ ), and excited by ultraviolet to blue light emitting elements And a phosphor that emits green to yellow light.

It is sectional drawing which shows the light-emitting device concerning this embodiment.

Hereinafter, this embodiment will be described in detail.
The phosphor according to the present embodiment uniformly coats the surface of the phosphor particles and europium and manganese-activated alkaline earth magnesium silicate phosphors that are excited by ultraviolet to blue light to emit green to yellow light. , Calcium pyrophosphate (Ca ₂ P ₂ O ₇ ), magnesium pyrophosphate (Mg ₂ P ₂ O ₇ ), barium pyrophosphate (Ba ₂ P ₂ O ₇ ), strontium pyrophosphate (Sr ₂ P ₂ O ₇ ), at least Or a coating layer made of one kind.

The phosphor according to the present embodiment is a phosphor mainly composed of alkaline earth magnesium silicate with europium (Eu) and manganese (Mn) as activators and coactivators, respectively. More specifically, it is composed mainly of europium having a composition substantially represented by the chemical formula: (Sr, Ba, Mg) ₂ SiO ₄ : Eu, Mn, manganese-activated alkaline earth magnesium silicate, A green to yellow phosphor that emits green or yellow light when excited by the emission of blue light.

In the phosphor of the present embodiment, the emission color of the phosphor can be changed in a wide range by changing the composition ratio of the alkaline earth metal and magnesium (Sr, Ba, Mg) as the base material. Specifically, in Eu-activated strontium silicate phosphor (Sr ₂ SiO ₄ : Eu), yellow is obtained by substituting a part of Sr with Ba in the range of 0.1 to 1.7 moles. Luminescence intensity in the blue region can be changed by substituting Mg in the range of 0.01 to 0.15 mol, and in the red region by substituting Mn in the range of 0.001 to 0.01 mol. The emission spectrum of each wavelength region can be arbitrarily increased or decreased.

  Here, the lower limit value of the addition amount of each element is a limit value where an effective emission spectrum change is not observed if it is less than that, and the upper limit value of the addition amount is that each element has a sufficient spectrum change effect. This is set in consideration of the density balance between the two. The molar ratio between Mg and Mn is preferably higher with Mg. When Mn is more than Mg, the resulting crystal powder is colored and the brightness is lowered.

  Europium (Eu) is an activator (main activator) that forms a light emission center, and has a high transition probability, and therefore has high light emission efficiency. Eu, which is the main activator, preferably replaces a part of the alkaline earth element in the range of 0.025 to 0.25 mol. If the Eu content is out of this range, the light emission luminance decreases. More preferably, it is the range of 0.05-0.2 mol.

That is, the phosphor particles of the present embodiment has the _{formula: (Sr 2-x-y} -z-u, Ba x, Mg y, Eu z, Mn u) SiO 4 (0.1 ≦ x ≦ 1.7, 0.01 ≦ y ≦ 0.15, 0.025 ≦ z ≦ 0.25, 0.001 ≦ u ≦ 0.01), and preferably activated europium and manganese-activated alkaline earth magnesium silicate.

The europium and manganese-activated alkaline earth magnesium silicate phosphor according to the present embodiment can be produced, for example, by the method shown below.
First, a phosphor raw material containing an element constituting a phosphor base material and an activator (main activator and coactivator) or a compound containing the element has a desired composition ((Sr, Ba, Mg) ₂ SiO ₄ : Eu · Mn), and if necessary, ammonium chloride or the like is added as a flux if necessary, and these are mixed in a dry method.

  Specifically, a predetermined amount of strontium oxide, barium oxide, magnesium oxide, and silicon dioxide are mixed, and an appropriate amount of activator europium oxide and coactivator manganese oxide and flux are added to obtain a phosphor material. . Instead of strontium oxide, barium oxide, and magnesium oxide, carbonates such as strontium carbonate, barium carbonate, and magnesium carbonate may be used. As an activator, europium oxalate or europium carbonate can be used, and manganese carbonate, manganese oxalate, or the like can be used as a coactivator.

Next, such a phosphor material is filled in a heat-resistant container such as an alumina crucible together with activated carbon. After this mixed material is filled in a heat-resistant container, it is fired in a reducing gas atmosphere (for example, an atmosphere of 3 to 10% hydrogen-balance nitrogen). Firing conditions are important in controlling the crystal structure of the phosphor matrix ((Sr, Ba, Mg) ₂ SiO ₄ ). The firing temperature is preferably in the range of 1100 to 1400 ° C. Although the firing time depends on the set firing temperature, it is preferably 2 to 8 hours, and after firing, it is preferable to cool in the same atmosphere as during firing. Thereafter, the obtained fired product is washed with ion-exchanged water through a pulverization step, dried, and then subjected to sieving to remove coarse particles as necessary, thereby activating europium and manganese-activated alkaline earth. A magnesium silicate phosphor can be obtained.

  The phosphor material can be fired using a rotary heating furnace as described below. That is, the above-described phosphor raw material is put into a rotating tubular heating furnace that is arranged to be inclined with respect to the horizontal direction, and is continuously passed. Then, the phosphor material is rapidly heated to a predetermined firing temperature in the heating furnace, and the furnace is moved from the upper side to the lower side while rolling according to the rotation of the heating furnace. In this way, the phosphor material is heated and fired for a necessary and sufficient time. Thereafter, the fired product is continuously discharged from the heating furnace, and the discharged fired product is rapidly cooled. In such a firing step, the inside of the tubular heating furnace and the cooling part of the fired product discharged from the heating furnace are preferably maintained in an oxygen-free state from which oxygen has been removed. It is desirable to maintain in an inert gas atmosphere such as argon or nitrogen or a reducing gas atmosphere containing hydrogen.

  According to such a firing method, since the phosphor material is rapidly heated while rolling in the process of moving in the heating furnace, uniform thermal energy can be applied to the phosphor material in an oxygen-free state. As a result, the firing can be completed in a shorter time compared to the conventional firing method using a crucible, and efficient phosphor particles can be obtained without causing a decrease in luminance due to thermal history. In addition, since the aggregation of the phosphor particles can be suppressed by this firing method, it is not necessary to perform pulverization after firing, and deterioration of the phosphor due to repeated pulverization steps can be suppressed. Furthermore, since the phosphor raw material is heated and fired while rolling in the heating furnace, phosphor particles having a uniform particle diameter in a shape close to a sphere can be obtained.

The surface of the phosphor particles obtained by the above method is coated with calcium pyrophosphate (Ca ₂ P ₂ O ₇ ), magnesium pyrophosphate (Mg ₂ P ₂ O ₇ ), barium pyrophosphate (Ba ₂ P ₂ ) using a coating agent. Surface treatment for uniformly coating at least one metal pyrophosphate salt of O ₇ ) and strontium pyrophosphate (Sr ₂ P ₂ O ₇ ) is performed. Thus, by forming a film (coating layer) of the above-described metal pyrophosphate on the surface of the phosphor particles, the weather resistance of the phosphor under high temperature and high humidity is improved, and the luminance decreases with time from green to yellow emission. And the luminance maintenance rate is high.

  Since the coating (coating layer) is a non-light emitting component, an excessive amount of coating causes a significant decrease in luminance of the obtained phosphor. On the other hand, if the coating on the phosphor is insufficient, it is difficult to obtain the weather resistance effect. From such a viewpoint, the film (coating layer) is preferably in the range of 0.05 to 5.0% by weight with respect to the phosphor particles.

Specifically, the surface treatment with the coating agent is carried out as follows. That is, phosphor particles prepared as described above are dispersed in water or a mixture of water and ethyl alcohol (C ₂ H ₅ OH), and as a coating agent, pyrophosphoric acid such as sodium pyrophosphate or potassium pyrophosphate is used. Using salt and at least one of calcium, magnesium, barium, and strontium chloride, weigh and inject the phosphor particles so as to be reactively coated in the range of 0.05 to 5.0% by weight. . In addition, the temperature of the phosphor dispersion liquid in the surface treatment is preferably 25 ° C to 40 ° C.

  After the coating agent is added, the resulting phosphor is stirred for 30 minutes to 120 minutes, and the resulting phosphor is washed, filtered, dried, and sieved so that the phosphor particle surface is uniformly coated with pyrophosphate. Is obtained. The europium and manganese-activated alkaline earth magnesium silicate phosphors thus obtained have excellent weather resistance.

The average particle diameter of the europium and manganese-activated alkaline earth magnesium silicate phosphor of the present embodiment is not particularly limited, but is preferably in the range of 10 μm to 20 μm. The average and particle size means the D ₅₀ showing a particle size of 50% by weight integrated value.

  Further, the obtained europium and manganese-activated alkaline earth magnesium silicate phosphor is a phosphor that emits green to yellow light when excited by radiation of an ultraviolet or blue light emitting element, and has a good luminous efficiency. High luminance can be obtained. Therefore, by using this phosphor as a green to yellow light emitting phosphor, it is possible to realize a light emitting device such as an LED lamp with high emission luminance.

  Next, a light-emitting device having a light-emitting unit that includes the above green to yellow phosphor will be described. The white lamp will be described. FIG. 1 is a cross-sectional view schematically showing a configuration of a white lamp used in the light emitting device according to the present embodiment.

  As shown in FIG. 1, a light emitting device (LED device) 1 includes an insulating substrate 3 having electrodes 2A and 2B formed on the surface, an LED element 4 as a light emitting element mounted on the insulating substrate 3, and an LED element 4. A reflector base 5 for forming a concave portion to be housed, a reflector 6 affixed with a reflector 5a that is arranged inside the reflector base 5 and reflects light emitted from the LED element 4 in the front direction, and a transparent resin 7 It comprises a transparent resin sealing layer 9 in which phosphor particles 8 are dispersed, and a bonding wire 10 for energizing the LED element 4 from the electrode 2B. In the white lamp of this embodiment, the transparent resin sealing layer (phosphor-containing layer) 9 that is a light-emitting portion contains a red phosphor that emits red light together with the green to yellow light-emitting phosphor of this embodiment. Thus, a white LED lamp can be obtained.

Here, the red phosphor that emits red light is a phosphor that emits red light when excited by a blue light emitting LED chip. Specifically, for example, Eu-activated Sr, Ca nitride fluorescence. Body, Eu-activated Ca nitride phosphor, Eu-activated Sr, Ca sulfide phosphor, Eu-activated Ca sulfide phosphor, Eu, Ce-activated Ca sulfide phosphor, Eu, Sm-activated La oxysulfide At least one phosphor selected from the product phosphors is used. In such an LED lamp, high-luminance white light with high color rendering is obtained by color mixing of green light to yellow light emitted from green to yellow phosphors and red light emission emitted from red phosphors.
In FIG. 1, an LED element is used as the light-emitting element, but other light-emitting elements such as an EL element can also be used.

Hereinafter, specific examples of the present invention will be described. However, the present invention is not limited to these examples, and the present invention can be arbitrarily modified and implemented without departing from the gist of the present invention.
<Fabrication of phosphor>
Examples 1 to 4, Reference Examples 1 to 6
The raw material containing the phosphor matrix and the element constituting the activator or the compound containing the element, the Mg and Mn amounts are constant, and the Sr, Ba and Eu amounts are changed to change from the green region to the yellow region. In addition, it was weighed with the composition shown in Table 1 below.

Sample No. shown in Table 1 Ammonium chloride was added as a flux to each of the phosphor materials 1 to 10 and mixed well.
Appropriate amount of activated carbon is added to each phosphor material obtained, filled in an alumina crucible, and fired at 1200 ° C. for 5 hours in a reducing gas atmosphere (3 to 10% hydrogen-balance nitrogen atmosphere). It was. The obtained fired products were pulverized and sieved, and further fired at 1250 ° C. for 5 hours in a reducing gas atmosphere. Thereafter, each fired product obtained was pulverized and sieved, washed with water and dried, and further sieved to obtain sample Nos. Shown in Table 1. Europium and manganese-activated alkaline earth magnesium silicate phosphors having a composition of 1 to 10 ((Sr, Ba, Mg) ₂ SiO ₄ : Eu, Mn) were obtained.

The obtained sample No. 1 to 10 were dispersed in a mixed solution of water and ethyl alcohol (C ₂ H ₅ OH). After preparing each phosphor dispersion of 1 to 10, sample No. 1 was obtained using calcium chloride, magnesium chloride, barium chloride, strontium chloride together with sodium pyrophosphate or potassium pyrophosphate. Each phosphor of 1 to 10 was weighed and charged so as to be coated with pyrophosphate shown in Table 2 in the range of 0.05 to 5.0% by weight. At this time, the temperature of the phosphor dispersion liquid was set to 30 ° C., and after stirring for 90 minutes, filtration, drying and sieving were carried out, and the phosphor surface shown in Table 2 below was uniformly coated on the phosphor surface. The phosphors of Examples 1 to 4 and Reference Examples 1 to 6 were obtained.

Comparative Examples 1-10
Sample No. Each phosphor of Comparative Examples 1 to 10 was obtained in the same manner as in Examples 1 to 4 and Reference Examples 1 to 6, except that 1 to 10 was not coated with a coating agent (surface treatment agent).

<Powder evaluation>
5 g of each of the phosphor powders of Examples 1 to 4, Reference Examples 1 to 6, and Comparative Examples 1 to 10 prepared as described above were weighed in a 50 ml beaker and placed in a high-temperature and high-humidity atmosphere (temperature 85 ° C., A forced weather resistance test was conducted for 72 hours in a high-temperature and high-humidity tank having a humidity of 85%), and the luminance of the phosphor after the test was measured.
The emission luminance (initial value before the test) of each example and each reference example is the reference value 100% of the emission luminance (initial value before the test) of the phosphor powder of each comparative example that was not subjected to the surface treatment. And obtained as a relative value.
In addition, for the forced weather resistance test of the phosphor powder, the luminance maintenance rate when the emission luminance before being put into a high-temperature and high-humidity tank (temperature 85 ° C./humidity 85%) is taken as 100% is calculated by the following calculation method [1]. Measured according to the formula.
Powder luminance maintenance ratio (%) = Luminance luminance after forced weathering test / Luminance luminance before forced weathering test × 100 [1]
Moreover, the body color change of each phosphor after the forced weather resistance test was confirmed visually.
Table 3 shows the measurement results of the light emission luminance and the luminance maintenance ratio and the evaluation results of the body color change.

As is clear from the results shown in Table 3, the phosphor powders of Examples 1 to 4 and Reference Examples 1 to 6 of the present embodiment are compared with the phosphor powders of Comparative Examples 1 to 10 in terms of emission luminance ( In the initial value before the weather resistance test, there is a slight luminance difference due to the surface treatment, but in the luminance maintenance ratio of the forced weather resistance test in a high temperature and high humidity atmosphere (temperature 85 ° C, humidity 85%), both A decrease in luminance was not observed, and it was confirmed that the emission luminance was maintained. Further, in the evaluation of the body color change, the surface treatment did not show a change in the body color, but the comparative example without any surface treatment showed a phenomenon that the body color turned white. As a result of analyzing them with an X-ray diffractometer (XRD), a peak of strontium carbonate was confirmed in all of them. This is thought to be caused by the reaction between the moisture in the high-temperature and high-humidity tank and the phosphor matrix Sr (strontium), and the degree of whitening increases as the Sr (strontium) ratio increases. The maintenance rate also worsened.

That is, as defined in the present invention, europium, manganese-activated alkaline earth silicate phosphors are converted to calcium pyrophosphate (Ca ₂ P ₂ O ₇ ), magnesium pyrophosphate (Mg ₂ P ₂ O ₇ ), barium pyrophosphate ( In each example of the phosphor coated with reaction coating of Ba ₂ P ₂ O ₇ ) and strontium pyrophosphate (Sr ₂ P ₂ O ₇ ), the phosphor powder was placed in a high-temperature and high-humidity atmosphere (temperature 85 ° C./humidity 85%). From the above results, it was proved that the weather resistance and the luminance maintenance ratio in the weather resistance test were significantly improved as compared with the comparative examples which were not coated.

<Green LED lamp single color evaluation / yellow LED lamp single color evaluation>
Using the phosphor powders of Examples 1 to 4, Reference Examples 1 to 6, and Comparative Examples 1 to 10, LED lamps shown in FIG. 1 were produced as shown below.
That is, the phosphors of Examples 1 to 4, Reference Examples 1 to 6 and Comparative Examples 1 to 10 were used as green and yellow phosphors, and mixed in a mixture of an epoxy resin and an acid anhydride curing agent. Was dropped on a blue light emitting LED chip (0.4 mm square) 4 using a dispenser, the epoxy resin was cured, and then a hemispherical transparent epoxy resin cap was coated thereon. The light emitting device according to each reference example and each comparative example was manufactured, and the LED lamp was lit for 1000 hours in a high temperature and high humidity atmosphere (temperature 85 ° C., humidity 85%).

The emission brightness of each example and each reference example (initial value before the weather resistance test) is the emission brightness of the LED lamp using the phosphor powder without surface treatment of each comparative example (each initial value before the weather resistance test). Was determined as a relative value with respect to a reference value of 100%.
In addition, the LED lamp is lit for 1000 hours in a high-temperature, high-humidity atmosphere (temperature: 85 ° C., humidity: 85%), and brightness deterioration (weather resistance) is measured from the start of lighting to the end of lighting (after 1000 hours). ) A test was conducted, and the luminance maintenance rate was measured according to the following calculation method [2].
LED luminance maintenance ratio (%) = emission luminance after luminance degradation test / emission luminance before luminance degradation test × 100 ... [2]
Table 4 shows the measurement results of the light emission luminance and the luminance maintenance rate.

As is clear from the results shown in Table 4, the emission luminance (initial value before the weather resistance test) of the green and yellow LED lamps using the phosphor powders of Examples 1 to 4 and Reference Examples 1 to 6 was compared. Compared with the green and yellow LED lamps using the phosphor powders of Examples 1 to 10, there was almost no difference due to the presence or absence of surface treatment, but in a high-temperature and high-humidity atmosphere (temperature 85 ° C./humidity 85%). In the luminance degradation (weather resistance) test, it was confirmed that the luminance maintenance rate was improved as compared with the comparative example.

That is, as specified in the present invention, europium, manganese-activated alkaline earth magnesium silicate phosphor , calcium pyrophosphate (Ca ₂ P ₂ O ₇ ) in addition to magnesium pyrophosphate (Mg ₂ P ₂ O ₇ ) or magnesium pyrophosphate. ) , Single-color LED lamps using phosphors reactively coated with a mixture of at least one of barium pyrophosphate (Ba ₂ P ₂ O ₇ ) and strontium pyrophosphate (Sr ₂ P ₂ O ₇ ) In the high temperature and high humidity atmosphere (temperature 85 ° C, humidity 85%), the luminance maintenance rate of the luminance deterioration (weather resistance) test is compared with each comparative example of a single color LED lamp using a phosphor not coated. From the above results, it was proved that there was a significant improvement.

<Evaluation of white LED lamp>
In order to evaluate as a white LED lamp, the LED lamp shown in FIG. 1 was produced as follows.
Reference Example 7
Sample No. Europium, a manganese-activated alkaline earth silicate phosphor, which is a green light-emitting phosphor of Reference Example 1 in which calcium pyrophosphate (Ca ₂ P ₂ O ₇ ) is surface-treated with respect to the phosphor of Sample 1, From the lamp, europium, a manganese-activated alkaline earth magnesium silicate phosphor, which is a yellow light-emitting phosphor of Example 1 in which magnesium pyrophosphate (Mg ₂ P ₂ O ₇ ) was surface-treated on the phosphor of No. 2 , was used. A red light-emitting phosphor nitride-based red light-emitting phosphor (CaAlSiN ₃ : Eu) was mixed so that the white light emission was white. This phosphor for GYR white LED is mixed with a mixed liquid of an epoxy resin and an acid anhydride curing agent, and the liquid is dropped onto a blue light emitting LED chip (0.4 mm square) 4 using a dispenser. After the epoxy resin was cured, a hemispherical transparent epoxy resin cap was coated thereon to produce a white LED lamp according to Reference Example 7.

Reference Example 8
Sample No. No. 3 phosphor, strontium pyrophosphate (Sr ₂ P ₂ O ₇ ), and the green light emitting phosphor of Reference Example 2 , europium, manganese-activated alkaline earth magnesium silicate phosphor, Using the yellow-emitting phosphor europium and manganese-activated alkaline earth magnesium silicate phosphor of Reference Example 3 in which barium pyrophosphate (Ba ₂ P ₂ O ₇ ) was surface-treated on the phosphor of No. 4 from the lamp A red light-emitting phosphor nitride-based red light-emitting phosphor (CaAlSiN ₃ : Eu) was mixed so that the white light emission was white. This phosphor for GYR white LED is mixed with a mixed liquid of an epoxy resin and an acid anhydride curing agent, and the liquid is dropped onto a blue light emitting LED chip (0.4 mm square) using a dispenser to form an epoxy. After the resin was cured, a hemispherical transparent epoxy resin cap was coated thereon to produce a white LED lamp according to Reference Example 8 .

Comparative Example 11
Except for using the green-emitting phosphor europium and manganese activated alkaline earth silicate phosphor of Comparative Example 1 and the yellow-emitting phosphor europium and manganese activated alkaline earth magnesium silicate phosphor of Comparative Example 2 Treated as in Example 11. That is, calcium pyrophosphate (Ca ₂ P ₂ O ₇ ) and sample No. A white LED lamp according to Comparative Example 11 in which the phosphor 2 was not coated with magnesium pyrophosphate (Mg ₂ P ₂ O ₇ ) was produced.

Comparative Example 12
Except for using the green-emitting phosphor of Comparative Example 3 europium and manganese-activated alkaline earth magnesium silicate phosphor and the yellow-emitting phosphor of Comparative Example 4 europium and manganese-activated alkaline earth magnesium silicate phosphor. Treated as in Example 12. That is, sample no. 3 phosphors of strontium pyrophosphate (Sr ₂ P ₂ O ₇ ) and sample no. A white LED lamp according to Comparative Example 12 in which the phosphor 4 was not coated with barium pyrophosphate (Ba ₂ P ₂ O ₇ ) was produced.

With respect to the white LED lamps according to Reference Examples 7 and 8 and Comparative Examples 11 and 12, the light emission luminance was measured.
In addition, each light-emitting luminance was calculated | required as a relative value with respect to the light-emitting luminance of the white LED lamp of the comparative example 11 as the reference value of 100%.
In addition, a white LED lamp is lit for 1000 hours in a high-temperature and high-humidity atmosphere (temperature: 85 ° C., humidity: 85%), and brightness deterioration (weather resistance) is measured from the start of lighting to the end of lighting (after 1000 hours). The brightness maintenance rate was measured according to the following calculation method [3].
Luminance maintenance ratio (%) = Luminance luminance after luminance degradation test (%) ÷ Luminescence luminance (%) × 100 ... [3]
Table 5 shows the measurement results of the light emission luminance and the luminance maintenance rate.

As is clear from the results shown in Table 5, sample No. 1 and no. The white LED lamp according to Reference Example 7 in which Ca ₂ P ₂ O ₇ and Mg ₂ P ₂ O ₇ were surface-treated with respect to 2, compared with the white LED lamp according to Comparative Example 11 that was not surface-treated, Although there is almost no difference in the luminance of white light emission, it can be seen that the luminance is greatly improved after a luminance deterioration test under a high temperature and high humidity atmosphere (temperature 85 ° C., humidity 85%). Sample No. 3 and no. 4, the white LED lamp according to Reference Example 8 in which Sr ₂ P ₂ O ₇ and Ba ₂ P ₂ O ₇ were surface-treated, compared with the white LED lamp according to Comparative Example 12 that was not surface-treated, Although there is almost no difference in the luminance of white light emission, it can be seen that the luminance is significantly improved after the light emission luminance deterioration test in a high temperature and high humidity atmosphere (temperature 85 ° C., humidity 85%).

That is, as defined in the present invention, europium, manganese-activated alkaline earth magnesium silicate phosphor, calcium pyrophosphate (Ca ₂ P ₂ O ₇ ), magnesium pyrophosphate (Mg ₂ P ₂ O ₇ ), barium pyrophosphate ( By using a phosphor coated with at least one of Ba ₂ P ₂ O ₇ ) and strontium pyrophosphate (Sr ₂ P ₂ O ₇ ), a white LED lamp can be used in a high temperature and high humidity atmosphere (temperature 85). From the above results, it was proved that the luminance maintenance rate in the luminance deterioration (weather resistance) test at a temperature of 85 ° C./humidity was greatly improved.

According to the phosphor according to the present invention, green to yellow light is emitted by excitation of the blue LED. Furthermore, calcium pyrophosphate (Ca ₂ P ₂ O ₇ ), magnesium pyrophosphate (Mg ₂ P ₂ O ₇ ), barium pyrophosphate (Ba ₂ P ₂ O ₇ ), strontium pyrophosphate (Sr ₂ P) By coating with at least one of ₂ O ₇ ), it becomes possible to realize a light emitting device such as a white LED lamp having excellent weather resistance such as heat resistance and moisture resistance.

Claims (6)

Europium and manganese activated alkaline earth magnesium silicate phosphor particles excited by ultraviolet to blue light and emitting green to yellow light,
The phosphor uniformly covers the surface of the particles, in addition to magnesium or the magnesium pyrophosphate pyrophosphate, calcium pyrophosphate, to have a coating layer comprising a mixture of at least any one of barium pyrophosphate, and pyrophosphate strontium A phosphor characterized by.   The phosphor according to claim 1, wherein the coating layer is 0.05 to 5% by weight with respect to the phosphor particles. Said phosphor particles, the chemical _{formula: (Sr 2-x-y} -z-u, Ba x, Mg y, Eu z, Mn u) SiO 4 (0.1 ≦ x ≦ 1.7,0.01 ≦ y ≦ 0.15,0.025 ≦ z ≦ 0.25,0.001 ≦ u ≦ 0.01) , wherein the europium and manganese activated alkaline earth magnesium silicate represented by claims 1 or The phosphor according to claim 2 . A light emitting device comprising: the phosphor according to any one of claims 1 to 3 ; and a light emitting element that emits ultraviolet to blue light that excites the phosphor to emit light. The light emitting device according to claim 4 , wherein the light emitting element is an LED. In addition to magnesium pyrophosphate or magnesium pyrophosphate in water or in an aqueous alcohol solution on the surface of europium and manganese activated alkaline earth magnesium silicate phosphor particles that are excited by ultraviolet to blue light to emit green to yellow light, calcium pyrophosphate A method for producing a phosphor, comprising a step of reactively coating a mixture of at least one of barium pyrophosphate and strontium pyrophosphate.

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