AU2001267136B2 - Phosphorescent pigments - Google Patents
Phosphorescent pigments Download PDFInfo
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- AU2001267136B2 AU2001267136B2 AU2001267136A AU2001267136A AU2001267136B2 AU 2001267136 B2 AU2001267136 B2 AU 2001267136B2 AU 2001267136 A AU2001267136 A AU 2001267136A AU 2001267136 A AU2001267136 A AU 2001267136A AU 2001267136 B2 AU2001267136 B2 AU 2001267136B2
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- phosphor pigment
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Description
WO 01/98433 PCT/AU01/00749 1 PHOSPHORESCENT PIGMENTS Technical Field This invention relates to improved long lasting phosphorescent pigments and methods for preparing these pigments.
Background to the Invention Fluorescence is a phenomenon where a material emits visible radiation when the material is excited by an external excitation source. A fluorescent lamp and a cathode ray tube each emit fluorescence. A material which emits fluorescence is called a phosphor. When light emitted by a phosphor lasts after cessation of excitation for a duration of time sufficient for the light to be perceived by the eye, about 0.1 second or longer, the light is called phosphorescence. A phosphor which has a long persistent phosphorescence lasting for several hours at room temperature is called a long-lasting phosphor or a light storage phosphor and it is to such materials that the present invention relates.
There are two types of prior art long-lasting phosphors materials namely a sulfide represented by ZnS:Cu and an Eu 2 activated alkaline-earth metal aluminate RA12 04 (R being an alkaline-earth metal). The ZnS:Cu sulfide type of long-lasting phosphors have been used for several decades but they have the disadvantage that their after-glow lasts for a relatively short duration of time, usually, about three hours at the longest. Furthermore, this type of phosphor has a serious defect in that a decomposition reaction of ZnS+H.aO and Zn+HS takes place under the coexistence of ultraviolet ray contained in the sunlight and moisture contained in the air. This renders the phosphor black in colour and, as a result, the after- glow characteristics significantly deteriorate within a relatively short period of time. For this reason, this type of phosphor has had only limited applications such as a luminous watch and a night-time display of a location in a house.
004664406 2 t In order to improve the brightness and the length of after-glow, radioactive luminescent 0 materials have been made, in which some radioactive elements such as Co,Ra,H 3 were added.
(N
C, Such modifications can lead to the phosphor continuously giving out light. These phosphors C/ have been used in aircraft dashboards and clocks. However, due to the possibility of radioactive contamination and the relatively high cost, the application of these phosphors has been severely limited.
¢3 Relatively Eu 2 activated alkaline metal aluminate long lasting phosphors have been S developed Pat. Nos. 5,376,303 and 5,424,006). These exhibit higher phosphorescence brightness, longer after-glow lifetime as well as better chemical durability and light resistance than the ZnS:Cu phosphors. These newly developed aluminate phosphors are anticipated to have wide applications such as signage, in addition to the existing applications for luminous watches and vehicle instruments.
Most of the known phosphor materials are subject to hydration when suspended in an aqueous solution and this causes them to suffer deterioration of performance. This in turn prevents the use of these materials in certain applications and in particular as pigments in water-based paints.
Their use is limited to solvent-based solutions, resins, binders and heat formed compound plastics.
However, their use in these applications is further limited to varying degrees from other negative characteristics. For example, it is not practical to obtain a stable suspension of known phosphor materials in solutions or emulsions because the phosphor material tends to settle. This is due to the high specific gravity of the phosphor materials which are typically in excess of 3 g/cm 3 If settlement occurs with these phosphor materials the particles tend to solidify into a mass that is extremely difficult to break up and redisperse throughout the solution or emulsion. This characteristic of the phosphor materials dictates that the untreated phosphor materials be suspended in a given solution or emulsion on an in-situ basis immediately before use. In many applications this can be inconvenient.
A further problem arises with many known phosphor materials. They tend to be hard materials with various crystal structures. The hardness and crystal structures combine to make the phosphor materials highly abrasive. These characteristics are the largest contributors of frictional wear on processing machinery such as discs involving the use of phosphor materials with compound plastics and solutions. This frictional wear results in premature machinery wear and costly maintenance.
004731839 3 As well as the aluminate phosphors discussed above, silicate phosphors are also known.
Furthermore, phosphors which contain a mixture of silicon and aluminium are known. Apart O from limitations with colour and the length of the after-glow these known phosphors have other S deficiencies, some of which have been described above.
OO
Summary of the Invention
ID
I_ This invention provides in one form an improved long lasting phosphor pigment composition comprising:
(N
to 95 wt of an inorganic long lasting phosphor pigment; to 95 wt of ceramic balloon microspheres, hollow ceramic microspheres or expanded siliceous material, such as expanded perlite, wherein the outer surface of the ceramic microspheres or expanded siliceous material are bonded to the phosphor pigment.
Preferably the ceramic microspheres are glass.
Preferably the ceramic microspheres are borosilicate glass.
Preferably the inorganic phosphor is a Eu 2 activated alkaline earth metal aluminate or silicate or aluminate/silicate.
Preferably the wt of inorganic phosphor pigment is in the range 40 to 80% and the wt of the ceramic or silica particles is in the range 20 to Preferably the density or specific gravity of the improved phosphor pigments is in the range 0.20 1.50 g/cm 3 and more preferably 0.30 1.20 g/cm 3 and even more preferably 0.40 1.00 g/cm 3 In an alternative form the invention provides a process for preparing an improved phosphor pigment composition comprising the steps of: treating an inorganic phosphor pigment to hydrate the surface of the phosphor pigment; bonding the outer surface of ceramic microspheres or expanded siliceous material to the surface of the inorganic long lasting phosphor pigment.
004731839 4 S Detailed Description of the Invention N The first step in the treatment process advances the natural hydration of the phosphor 0 type material. This is achieved utilising a strong acid, such as 15% hydrochloric acid, 85% water O solution, which effectively pre-hydrates the phosphor materials at a rapid rate, and in a controlled manner, so as to render the materials natural hydration process mostly spent and does so without detrimental effect on its performance. This allows the suspension of the treated phosphors at a high solids content in polymer solutions and emulsions. Other strong acids such as phosphoric acid may also be used by adjusting the concentration of the acid in water to suit.
The heat resistant ceramic or siliceous balloon microsphere is bonded to the surface of N, the hydrated surface of the phosphor pigment as follows. In a preferred process the soda lime borosilicate glass spherical bubbles (Na,CO,.CaO.SiO,NaO,KO,BO,AIO) are attached or bonded to the phosphor material. It will be appreciated that in this process that as the bubbles are attached or bonded to the phosphor material that the bond is formed between the outer surface of the glass bubble and the phosphor. The micro spherical glass bubble or balloon used has a very low specific gravity by weight, typically 0.15 g/cm 3 It is chemically inert and exhibits high heat and crush resistance qualities. They are hollow glass spheres. By attaching or bonding the particles of phosphor materials to the glass micro spherical bubbles the specific gravity of the modified phosphor materials is able to be reduced. The reduction in specific gravity is directly related to the ratio of the volume of phosphor materials to the volume of glass micro spherical bubbles. By using this method it is possible to design a specific gravity by volume ranging from approximately 0.18 g/cm 3 to close to the natural specific gravity by volume of the untreated phosphor material concerned (eg. 4.2 g/cm 3 in Example The preferred density of the modified phosphor is in the range 0.20 1.50 g/cm 3 more preferably 0.30 1.20 g/cm 3 and most preferably 0.40 1.00 g/cm 3 The micro spherical glass bubbles that are used have sufficient optical clarity so as not to interfere with the irradiation and correspondingly the radiation of the phosphor materials. This effectively maintains the normal operation of the phosphor materials including their normal range of excitation frequencies, exposure durations, discharge frequency ranges and durations.
The treated phosphor materials can then be permanently suspended across the viscosity range encountered in any solutions that it may be required.
004664406 l The bond achieved is believed to be a weak valence bond established by the hydration reaction of phosphor materials and the soda lime borosilicate glass micro spherical bubbles when s:4 jointly exposed to a strong acid, water solution such as 15% hydrochloric acid/85% water.
1D Surprisingly we have also found that amorphous silica may be used to achieve excellent results when used to partially replace the preferred glass spherical bubbles. Low density products are also achieved. Although the optical clarity using amorphous silica is less than that achieved N using glass microballoons satisfactory performance can be also achieved for certain purposes when the amorphous silica partially replaces the ceramic balloon microspheres. Other ceramic NO or silica materials can be used such as Ceramic Microspheres supplied by 3M and expanded perlite which is a form of siliceous lava. The Ceramic Microspheres supplied by 3M are silica- 1 alumina ceramic microspheres, such as W-1012, which have a specific gravity of 0.7 g/cm 3 a particle size ranging from 10-125 microns and a pH of 7.
Glass bubble microspheres supplied by 3M include product grades K1, K15, K20, K25, K37, K46, S15, S22, S32, S60/10,000, B38/4000, A16/500, A20/1000, H20/1000, D32/4500, H50/10,000 EPX).
The glass bubble microspheres typically possess the following properties: Specific gravity g/cm 3 0.1-0.63 Particle size (im) range 6 250 Softening point 600°C pH: 9.1-9.9 The soda lime borosilicate bubble micro spheres are typically in a fine powder form and may present a dust hazard during handling and processing. With this in mind, the micro spheres should be handled in accordance with the appropriate and relevant regulations pertaining to materials which present a dust hazard.
A sealed tumbler powder mixing system is preferably used. This is equipped with airflow drying and filtered air and vapour venting system. The treatment process may release a small amount of hydrogen gas in non-hazardous trace element quantities along with water vapour.
All equipment is constructed from stainless steel and is lined with polyethylene.
004664406 6 l t The invention will be further described by reference to a preferred embodiment described
O
O in the following examples.
Example 1 soda lime borosilicate microspheres 300g strontium aluminate phosphor pigment 700g hydrochloric acid 15% solution 1^ NO Into a plastic mixing vessel the following materials were added: Hydrochloric Acid (30% concentration) 500ml De-ionised water 500ml The soda lime borosilicate micro spheres were added to the tumbler mixer and then of the above hydrochloric acid solution was added.
The tumbler mixer was sealed and the contents agitated for 10 minutes.
In the tumbler mixer, the strontium aluminate phosphor pigment was spread over the acid moistened soda lime borosilicate micro spheres. After this addition, the tumbler mixer was again sealed and mixing was commenced with an airflow being pumped into the mixture. Traces of hydrogen gas and water vapour that were generated during the tumbling action were evacuated.
The tumbling mixing was continued for three hours or until the mixture was thoroughly dry.
The theoretical density of the phosphorescent pigment was 0.46 g/cm 3 using the Nemoto pigment.
Brand name "Scotchlite Glass Bubble K15". Particle size 15 125 Jim, pH 9, Specific Gravity 0.15 g/cm 3 Available from Zeelan Industries Inc., 3M Center Bldg, 220-8E- 04, St. Paul, MN, USA. Brand name "Luminova G300 M"(SrAl20 4 :Eu, Dy) or "Luminova BG300M" (Sr 4 A1 14 0 25 :Eu, Dy), Particle size 4.6 91 Lpm. pH 10. Specific Gravity 3.65 g/cm 3 Available from Nemoto Co. Ltd, 1-15-1, Kamigoi, Suginami-ku, Tokyo 167-0043, Japan.
004731839 to 7 S Example 2
O
Z Example 1 was repeated replacing the Nemoto pigment with an equal weight of pigment 0 0 from Shandong Lunbo. The pigment used was brand name "Lunbo G34-200-A1" or "Lunbo 200A" (MO.aA1203.bSiO2.cL.fX, where M is an alkaline earth metal (Sr, Ca, Mg, Ba); L is a -O 5 mineraliser; X is an activator and one of the rare earth elements and a, b, c and f are numerical values.), Particle size 4.0 95 atm. pH 10. Specific Gravity 4.2 g/cm Available from
F-
S Shandong Lunbo Ind. Comm. Group Co Ltd, 3/86 Chaoshan Street, Jinan, Shandong, China.
The modified pigment was prepared as in Example 1 and exhibited similar properties except that the theoretical density was 0.45 g/cm 3 Since modifications within the spirit and scope of the invention may be readily effected by persons skilled in the art, it is to be understood that the invention is not limited to the particular embodiment described, by way of examples, hereinabove.
Example 3 soda lime borosilicate microspheres 200g strontium aluminate phosphor pigment 800g hydrochloric acid 15% solution The method of Example 1 was repeated, using the Nemoto pigment, but in this case a different grade of soda lime borosilicate microspheres was used.
Brand name "Scotchlite Glass Bubble S22". Particle size 6 125 Pm, pH 9.5, True density 0.22 g/cm 3 Available from Zeelan Industries Inc., 3M Center Bldg, 220-8E-04, St.
Paul, MN, USA.
The modified pigment exhibits similar properties to that of Example 1 except that the theoretical density is 0.88.
Example 4 ceramic microspheres 200g strontium aluminate phosphor pigment 800g 004731839 t 8 0 hydrochloric acid 15% solution S The method of Example 2 was repeated, using the Lunbo pigment, but in this case the soda lime 00 borosilicate microspheres were replaced with ceramic microspheres.
Brand name "Zeelan Industries Inc, Z-Light Spheres Microspheres W-1012". Particle size 10 125 pm, pH 7, True density 0.7 g/cm 3 Available from Zeelan Industries Inc., 3M Center Bldg, 220-8E-04, St. Paul, MN, USA.
The modified pigment exhibits similar properties to that of Example 2 except that the theoretical density is 2.10 and the optical clarity is slightly diminished.
Claims (19)
1. An improved long lasting phosphor pigment composition comprising: 00 to 95 wt of an inorganic long lasting phosphor pigment; D 5 to 95 wt of ceramic balloon microspheres wherein the outer surface of the ceramic balloon microspheres are bonded to the phosphor pigment.
2. An improved long lasting phosphor pigment composition comprising: O (N 5 to 95 wt of an inorganic long lasting phosphor pigment; to 95 wt of hollow ceramic microspheres wherein the outer surface of the hollow ceramic microspheres are bonded to the phosphor pigment.
3. An improved long lasting phosphor pigment composition comprising: to 95 wt of an inorganic long lasting phosphor pigment; to 95 wt of expanded siliceous material, wherein the outer surface of the expanded siliceous material are bonded to the phosphor pigment.
4. The improved phosphor pigment composition of claim 3 wherein the expanded siliceous material is expanded perlite. An improved phosphor pigment composition as defined in claim 1 or 2 wherein the ceramic microspheres are glass.
6. An improved phosphor pigment composition as defined in claim 2 wherein the ceramic microspheres are borosilicate glass.
7. The improved phosphor pigment composition of claim 1 or 2 wherein the ceramic microspheres are silica-alumina ceramic.
8. The improved phosphor pigment composition in one of claims 1 to 7 wherein the ceramic microspheres are partially replaced by amorphous silica.
9. An improved phosphor pigment composition as defined in any one of claims 1 to 8 004731839 0 wherein the inorganic phosphor is a Eu 2 activated alkaline-earth metal aluminate. O Z 10. The improved phosphor pigment composition in one of claims 1 to 7 wherein the 0_ improved phosphor pigment is a strontium aluminate phosphor pigment.
11. The improved phosphor pigment of claim 9, wherein the chemical composition is SrA120 4 :Eu, Dy or Sr 4 A1 1 40 25 :Eu, Dy or MO.aAl20 3 .bSiO 2 .cL.fX, where M is an alkaline earth metal (Sr, Ca, Mg, Ba); L is a mineraliser; X is an activator and one of the rare earth elements; and a,b,c and f, are numerical values. CI 12. An improved phosphor pigment composition as defined in any one of claims 1 to 8 wherein the inorganic phosphor is a Eu 2 activated alkaline earth metal silicate.
13. An improved phosphor pigment composition as defined in any one of claims 1 to 12 wherein the weight percent of inorganic phosphor pigment is in the range 40 to 80% and the weight percent of the ceramic microspheres or expanded siliceous material is in the range 20 to
14. The improved phosphor pigment composition in any one of claims 1 to 13 wherein the density of the improved phosphor pigment is in the range 0.18 to less than 4.2 g/cm 3 An improved phosphor pigment composition as defined in claim 14 wherein the density of the improved phosphor pigment is in the range 0.20 to 1.50 g/cm 3
16. An improved phosphor pigment composition as defined in claim 15 wherein the density of the improved phosphor pigment is in the range 0.30 to 1.20 g/cm 3
17. An improved phosphor pigment composition as defined in claim 16 wherein the density of the improved phosphor pigment is in the range 0.40 to 1.00 g/cm 3
18. An improved phosphor pigment composition of one of claims 1 to 17 wherein the ceramic microspheres or expanded siliceous material has a diameter between the range of 15 125 Pjm.
19. An improved phosphor pigment composition in one of claims 1 to 17 wherein the improved phosphor pigment is moisture resistance. A process for preparing an improved phosphor pigment composition comprising the steps 004731839 va 11 N of treating an inorganic phosphor pigment to hydrate the surface of the phosphor pigment, O bonding the outer surface of the ceramic microspheres or expanded siliceous material of one of claims 1 to 3 to the surface of the inorganic phosphor pigment. 00
21. The process for preparing an improved phosphor pigment composition of claim ,D 5 wherein the surface of the phosphor pigment and the outer surface of the ceramic microspheres or expanded siliceous material are treated with a strong acid, water solution such as ,O hydrochloric acid/85% water.
22. The process for preparing an improved phosphor pigment composition as defined in claims 20 or 21 wherein the inorganic phosphor pigment is a Eu activated alkaline earth metal aluminate, silicate or aluminate/silicate.
23. A process for preparing an improved phosphor pigment composition comprising the steps substantially as hereinbefore described with reference to the examples.
24. An improved phosphor pigment composition substantially as hereinbefore described with reference to the examples. Dated 18 November 2005 Freehills Patent Trade Mark Attorneys Patent Trade Mark Attorneys for the Applicant: Nite-Glo Innovations Pty Ltd
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AU2001267136A AU2001267136B2 (en) | 2000-06-22 | 2001-06-22 | Phosphorescent pigments |
Applications Claiming Priority (6)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AUPQ8267 | 2000-06-22 | ||
| AUPQ8267A AUPQ826700A0 (en) | 2000-06-22 | 2000-06-22 | Luxalum photoluminescence pigment |
| AUPR4041 | 2001-03-28 | ||
| AUPR4041A AUPR404101A0 (en) | 2001-03-28 | 2001-03-28 | Improved phosphorescent pigments |
| AU2001267136A AU2001267136B2 (en) | 2000-06-22 | 2001-06-22 | Phosphorescent pigments |
| PCT/AU2001/000749 WO2001098433A1 (en) | 2000-06-22 | 2001-06-22 | Phosphorescent pigments |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| AU2001267136A1 AU2001267136A1 (en) | 2002-03-21 |
| AU2001267136B2 true AU2001267136B2 (en) | 2006-01-05 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| AU2001267136A Ceased AU2001267136B2 (en) | 2000-06-22 | 2001-06-22 | Phosphorescent pigments |
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| Country | Link |
|---|---|
| AU (1) | AU2001267136B2 (en) |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5122305A (en) * | 1990-03-20 | 1992-06-16 | Ashley Carol S | Solid-state radiation-emitting compositions and devices |
| WO2000011104A1 (en) * | 1998-08-25 | 2000-03-02 | Koninklijke Philips Electronics N.V. | Method of coating a luminescent material |
| JP2000087103A (en) * | 1998-09-03 | 2000-03-28 | Nittetsu Mining Co Ltd | Fluorescent multilayered film coated powder |
-
2001
- 2001-06-22 AU AU2001267136A patent/AU2001267136B2/en not_active Ceased
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5122305A (en) * | 1990-03-20 | 1992-06-16 | Ashley Carol S | Solid-state radiation-emitting compositions and devices |
| WO2000011104A1 (en) * | 1998-08-25 | 2000-03-02 | Koninklijke Philips Electronics N.V. | Method of coating a luminescent material |
| JP2000087103A (en) * | 1998-09-03 | 2000-03-28 | Nittetsu Mining Co Ltd | Fluorescent multilayered film coated powder |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PC1 | Assignment before grant (sect. 113) |
Owner name: NITE-GLO INNOVATIONS PTY LTD Free format text: FORMER APPLICANT(S): S.L.E. (AUSTRALIA) PTY LTD |
|
| FGA | Letters patent sealed or granted (standard patent) | ||
| MK14 | Patent ceased section 143(a) (annual fees not paid) or expired |