WO2007104665A1

WO2007104665A1 - Highly stable plastic component, which is suitable for luminescence

Info

Publication number: WO2007104665A1
Application number: PCT/EP2007/052052
Authority: WO
Inventors: Frank Jermann; Martin Zachau
Original assignee: Osram Gesellschaft mit beschränkter Haftung
Priority date: 2006-03-13
Filing date: 2007-03-05
Publication date: 2007-09-20
Also published as: DE102006011453A1

Abstract

The component is characterized by the fact that it is suitable for luminescence. This is brought about by inorganic phosphors in a plastic matrix.

Description

Title: High-resistant plastic component which is suitable for neszenz Lumi ^¬

Technical area

The invention is based on a highly resistant luminescent plastic component according to the preamble of claim 1. Such plastic components are of particular interest for technical devices such as cell phones.

State of the art

WO 2004/030109, US Pat. No. 6,669,866 and US Pat. No. 6,682,6683 disclose highly resistant inorganic phosphors, in particular for use in LEDs.

So far, luminescent plastics are always produced on the basis of organic phosphors. Disadvantage of this design is the generally low resistance to environmental influences such as the UV component of sunlight. The organic phosphors are easy to process and cheap. For use in "designer pieces" of higher price classes, such as cell phones, MP3 players (iPod), etc., these plastics are due to aging only partially suitable. Inorganic phosphors which can be excited in the visible spectral range, in particular in the cyan, green and red spectral range, have hitherto not been considered for this purpose. For example, a key illumination in mobile phones is also known through LED backlighting. Presentation of the invention

The object of the present invention is to provide a highly resistant plastic component, which is particular ^¬ DERS for technical devices which are electrically operated, is suitable.

This object is solved by the characterizing features ^¬ times of claim 1.

Particularly advantageous embodiments can be found in the dependent claims.

The following describes a possibility for producing white or colored luminescent plastic components with high resistance to environmental influences such as moisture, heat and sunlight. These plastic components can z. B. be used to facilitate the operation of equipment. In particular, they can be used to create differently colored luminescent areas with a uniform backlighting color. But even more important is the design aspect. With the help of these plastic components can be z. B. -optionally replaceable- housing shells for mobile, electronic devices such as cell phones, PDAs, MP3 players, etc. produce, for example, when the backlighting green, or depending on the phosphor yellow or red, appear, but with the lights on, z. B. as a result of a keystroke, a call, a stored appointment above, different, especially lagoon colors, or white or pink, shine. The phosphors present a body color, in particular when switched off, and when switched on they change to the color of the body Luminescence. This is preferably true for phosphors which are excited with blue primary radiation (peak at about 420 to 475 nm). In the case of a UV excitation, in particular at 350 nm, preferably 380 nm to 415 nm, the phosphor particles are rather colorless or white.

Furthermore, a presentation of the plastic component is attractive, in which the body color is covered by a thin plastic layer when illuminated from the outside (reflection), but which is so thin that it is transparent at backlighting. It is possible, for example, a coloring or darkening of the plastic by additional absorber similar to car taillights known. The reflected light passes through the plastic twice, while the emitted light has a shorter path through the "darkened" plastic. Therefore, in daylight, the plastic may look nearly black (or colored according to the additional absorption) while the color changes with luminescence.

A conventional plastic is mixed with inorganic phosphor particles (eg yellow YAG: Ce or other Ce-doped garnets or green to yellow

(Sr, Ca, Ba) Si2O2N2: Eu or red nitridosilicate

(Ba, Sr, Ca) 2Si5N8: Eu) as in WO

2004/030109, US 6,669,866 and US 66826683 described homogeneously mixed and in the desired shape

(three-dimensionally, two-dimensionally as a thin film, one-dimensionally as a marking line) (e.g., pour in the liquid state, extrude or the like, cure over temperature, irradiation or otherwise, with and without further additives). The composition and concentration of

Phosphors determine the color of the plastic, as well -A-

Body and luminescent color of the composite material. The phosphors should preferably be excitable in the visible or UV-A spectral range, since the plastics age strongly under the action of UV-B or UV-C radiation. Preference is given to phosphors which can be excited in a spectral range of> 420 nm, since even for <420 nm, the absorption and damage of the plastic increases. In general, that the phosphor is cerium and / or Euro ^¬ Pium is activated, wherein the phosphor contains at least one or more of the following elements: Al, Si, N, O, alkaline earth metals, rare-earth metals. Compounds of these classes have proven to be particularly effective and particularly durable.

Preferably, the phosphor should contain at least N and / or Si, more preferably together with at least one constituent from the group Al, Si or N, 0, in particular from the group nitrides, oxynitrides, sions, nitridosilicates, silicates, chlorosilicates and their Mi ^¬ shingles.

Suitable candidates are in particular the following luminescent materials ^¬: inorganic crystalline phosphor pigments that are excitable in the visible or UV-A spectral range, in particular grenade and nitride and oxynitride phosphors. They are characterized by excellent stability, in particular against

1) moisture, especially humidity

2) short-wave visible or UV radiation, especially those of the sun and the exciting light source;

3) Temperatures up to 15O ⁰ C and above. This is a characteristic not previously encountered with organic luminescent pigments which is extremely advantageous for a variety of applications. In particular, the conversion efficiency of the phosphors is very high and i. geng. relatively independent of the ambient temperature. This ensures that the desired effect is achieved even at different ambient temperatures. You can also mix different types of pigments to achieve different colors. A particularly suitable field is the construction of mobile phones in general and especially the application for plastic shells that are changeable, also keyboards or other parts of trays, not just for mobile phones, can be manufactured with it.

The grain sizes of the crystalline grains should normally have a volume-weighted average (median) d50 of at most 20 μm, in particular from 0.5 μm to 20 μm, since such phosphors have the highest quantum efficiencies.

So-called inorganic nano-phosphors with particle sizes d50 of <100 nm and in particular <50 nm are also particularly interesting since, firstly, they are easy to introduce into plastics, second, they are less scattered and thus have a weaker body color. Ultimately transparent, but luminescent plastics are therefore possible based on nano-phosphors.

Particularly with mobile phone keys, an exchangeable mobile phone shell with differently luminescent phosphors is now realizable. this is a completely new design option that is not possible with conventional LED backlighting.

The excitation of the phosphor in the plastic can be done by blue or UV-A light, e.g. produced by LEDs, compact fluorescent lamps or other lamps. In the case of mobile phone keyboards, the stimulation is effected in particular by blue LEDs. For linear

Marking strips or sheets is also the

Coupling of the light of linear fluorescent lamps or compact fluorescent lamps well suited.

Particularly suitable as plastic are silicones, epoxy resins, PMMA ("Plexiglas") and transparent PVC.

Brief description of the drawings

In the following, the invention will be explained in more detail with reference to several embodiments. The figures show:

Fig. 1 a mobile phone shell;

Figure 2 is a cell phone;

Fig. 3 is a keyboard for a mobile phone or a mobile phone shell.

Preferred embodiment of the invention

FIG. 1 shows two mobile phone shell parts 1 made of plastic. An upper part in Figure Ia and a lower part in Figure Ib, are composed of several parts. Some components 2 are made of plastic, which is colored and lights when Be ^¬ lighting and / or backlighting. As a luminous material is particularly YAG: Ce (yellow TERMS ^¬ on / yellow body color), Sr Sion SrSi2O2N2: Eu (green Emis ^¬ sion / green body color) and (Sr, Ca) 2Si5N8: Eu (red Emis ^¬ sion / red body color) ,

FIG. 2 shows a mobile phone 3 in plan view. Its housing 4 is made of plastic, wherein some components 5 have the luminescent ^¬ material as described in Figure 1 dispersed in the plastic matrix. The light source 6 is not visible as an LED band (blue LEDs with 460 nm peak as a primary emission) arranged along the phosphor-containing components inside the housing.

Figure 3 shows a plastics component 9 which includes, for example, only the Tasta ^¬ structure of a mobile phone or PDAs. The individual keys 10 are afflicted with various phosphors, for example, the yellow YAG key 11: Ce and the green Sr-sion key 12 and the key 13 with a mixture of both.

The mobile phone shell can in another embodiment with YAG: Ce filled as a phosphor show a yellow body color, as long as the phone is turned off. If the blue backlight is switched on, the mobile phone shell may shine white or even ice blue (little YAG dispersed in the plastic) or also glow yellow with different degrees of saturation (rather high YAG concentration). The red phosphor of the nitridosilicate can be excited in the blue or in the green (in particular up to 530 nm peak). These red / green combinations may look white when the lights are on, even though the phone is red or red-orange when turned off.

Claims

claims

1. High-resistant plastic component which is suitable for luminescence, characterized in that the luminescence ^¬ by means of inorganic phosphor particles he follows ^¬ , the radiation in a range well absorbed, which is between 380 and 620 nm, preferably between 380 and 475 nm, wherein the particles are embedded in a matrix of plastic, wherein the phosphor is activated with cerium and / or europium, and wherein the phosphor contains at least one or more of the following constituents: Al, Si, N, O, alkaline earth metals, rare earth metals Metals.

2. Plastic component according to claim 1, characterized in that the phosphor contains at least N and / or Si, preferably together with at least one constituent from the group Al, Si or N, 0, in particular from the group of nitrides, oxynitrides , SIO ne, nitridosilicates, silicates, chlorosilicates and de ^¬ ren mixtures.

3. Plastic component according to claim 1, characterized in that the component is a mobile phone shell or a

Part of it is.

4. Plastic component according to one of the preceding claims, characterized in that the phosphor particles ^{¬ have} a different body color from white.

5. Plastic component according to one of the preceding Ansprü ^¬ che, characterized in that the phosphor particles Particles from the group of garnets, nitrides, oxynitrides, Sione, nitridosilicates, silicates, chlorosilicates come, in particular from mixtures of these compound groups.

6. Electrical device, with a light source and a plastic component illuminatable therewith according to one of the preceding claims.

7. Apparatus according to claim 5, characterized in that the device includes a light source having its peak in the UV-A or in the blue spectral range, preferably in the range 380 to 475 nm.

8. Apparatus according to claim 5, characterized in that the device is a mobile phone.