DE10065946A1 - Platelet-shaped pressed body - Google Patents

Abstract

The invention relates to a lamellar pressed body (wafer), based on an inorganic sorbent and a binding agent, with a thickness of less than 700 mu m. Said wafer is obtained by pressing a mixture of the inorganic sorbent, binding agent, water and optionally auxiliary pressing agents at a pressure of at least 70 Mpa, whereby the weight ratio of the dry sorbent and the dry binding agent in the mixture lies between approximately 4 and 0.7 and the water content of the mixture, determined at 160 DEG C, lies between approximately 8 and 20 %. The green pressed body thus obtained is then calcined at temperatures of at least approximately 500 DEG C, until a considerable amount of the water content has been removed.

Description

The invention relates to platelet-shaped pressed bodies (wafer) based on an inorganic sorbent and one Binder, with a thickness of less than 700 microns due to its high mechanical strength and low brittleness distinguish and are able to use inorganic and organic effectively sorb gases or vapors.

The production of compacts, in particular tablets, based on zeolites and binders is already known. So are according to JP-A-61 15 5216 zeolite tablets by mixing a zeolite, a binder and one Lubricant and extruding the mixture. It are apparently tablets with the same dimensions in all directions.  

JP-A-56063818 describes the production of zeolite Ta Bletten known for use as gas adsorbents, wherein powdered and dried at 105 to 110 ° C zeolite 8.1% by weight of bentonite powder mixed with a 4% aqueous urea solution is kneaded. The mixture becomes ta bletted, dried and calcined at 510 ° C. The increase the compressive strength is due to the urea content.

JP-A-55 16 5144 discloses zeolite powder for cooling kneading aggregates in powder form with bentonite and water, extrude the mixture and round particles with one pass to shape knives from 0.8 to 10 mm.

According to JP-A-55 10 4913, zeolite is in the Na form with 25% by weight of clay mixed, kneaded with water, extruded, at Calcined at 650 ° C, immersed in a calcium chloride solution, ge wash, dry at 110 ° C and activated at 400 ° C. The Tablets are used as desiccants.

According to JP-A-4 603 2572, zeolite powder is mixed with kaolin and Na (or NH ₄ -) - hydroxyethyl cellulose, molded, dried and calcined at 650 ° C. to increase the strength of the zeolite tablets.

According to JP-A-21 44 121 deodorants are made by extrusion of zeolite powder or granules with calcium chloride or bento nit and water extruded, whereupon the mixture tablets and the tablets are calcined.

According to JP-A-63 218 234, drying agents are obtained by extruding a mixture of microporous particles (for example gypsum, cement, ceramic powder) and an inorganic or organic filler such as CaCl ₂ , LiCl, bentonite, zeolites, PVA or other water-soluble Polymers. The mixture is tabletted and then cured.

According to JP-A-60 132 643, zeolite tablets are called dry medium using 20% sepiolite as a binder posed. The mixture is kneaded with water, tabletted, dried at 150 ° C and calcined at 550 ° C. The tablets have an improved compared to bentonite tablets Drying power.

For use in confined spaces and un The mechanical stress is the state of the art Technically manufactured tablets are unsuitable because they are too thick and are too heavy and mass and surface related too rings have sorption power for harmful gases and vapors. With the processes and mixtures according to the prior art get too brittle compacts, especially after Crumble burning.

It is known that electroluminescent devices only then work easily over a long period of time if a Desiccant is present. This is due to the sensitivity the electrodes, especially the cathodes, e.g. B. opposite Moisture (the cathodes are made of Ca or Mg alloys). That is why these devices are under Shielding gas sealed as well as possible.

EP 500 382 A2 describes the use of a moisture absorber bers described in an electroluminescent device. The Desiccant in the form of a powder or small balls is applied to a black silicone resin coating. In the preferred embodiment, the desiccant is in filled in a gas-permeable bag.

US-A-5,882,761 also uses dry described in an electroluminescent device. BaO is used as the preferred desiccant.  

The sorbents known from the above publications have the disadvantage that they can only sorb water vapor. However, other gases can also attack the cathodes are triggered, which in addition to water when setting the ver seal used epoxy resin (ammonia, volatile Amines): In addition, the action of oxygen leads to Failure of the luminescent components (oxidation of the cathode).

The present invention is based, flatten the task Chen-shaped pressed body (wafer) based on an inorganic sorbent and an inorganic binder with a provide very small thickness (less than 700 microns), the have great strength despite their small thickness and such with be installed in particular in electronic components can in which only a limited space is available stands and can be exposed to vibrations (e.g. electronic display devices in automobiles and mobiles phones).

According to the invention, this object is achieved by provision of platelet-shaped pressed bodies (wafers) on the basis of a inorganic sorbent and a binder, with a thickness of less than 700 µm, which can be obtained by pressing a mixture consisting of or containing at least one inorganic sorbent, at least one binder, and counter also water and pressing aids, at a pressure of at least 70 MPa, the weight ratio of the dry sorbent and the dry binder between about 4 and 0.7 and the water content of the mixture, determined at 160 ° C, is between about 8 and 20%; and calcining the green compact obtained at temperatures of at least at least about 500 ° C until the total distance is largely removed serge halts.

The pressed bodies (wafers) according to the invention have a high Strength, low brittleness, high sorption speed  and high sorption capacities with low mass. You zei low thermal expansion, no abrasion and are easy to color by adding pigments during production.

The wafers according to the invention can be in automated processes can be produced in large numbers per unit of time. They are easy to handle and can be used for example So-called "pick-and-place" machines from a storage container men and be used in an electronic device.

The wafers according to the invention are able to, besides water other gases (ammonia, amines, oxygen) beers. Since they have a high sorption capacity, needs the electronic device in which they are inserted be completely airtight, d. H. the diffusion rate for water vapor in the device may be greater than zero. moreover is the selection of a suitable substance for sealing the Device (e.g. an epoxy resin) simplified because the critical time until this substance reaches its final lowest Water vapor permeability must have been reached by the A set of the wafer can be extended.

The inorganic sorbent is preferably a natural one or artificial zeolites. But others can also Sorbents, such as amorphous silica or aluminum hydroxide, as well as mixtures of two or more sorbents become.

In principle, any person skilled in the art can use this as a binder Binders which appear suitable in the field can be used. Be a smectite clay is preferred as the binder, in particular other bentonite used. The use of more is also on organic binders, e.g. B. alumina hydroxide (pseudo boehmit) possible. But organic binders can also be used be used on a carbohydrate or protein basis, e.g. B. Starch, cellulose derivatives (such as CMC or CEC), casein or  synthetic polymers such as PVA, PVP or polyphenols or tan binders containing nin (Quebracho). Mixtures can also be used different binders can be used.

The addition of bentonite to the zeolite is more surprising the sorption capacity of the latter is not reduced. In fact, there is a synergistic effect, i.e. H. the water vapor absorption of the mixture is after the calcination significantly less than pure zeolite would be expected purely mathematically.

The thickness of the wafer is preferably no more than about 400 microns, especially about 200 to 400 microns.

The invention further relates to a method in particular for the production of the compact defined above, the is characterized in that a mixture consisting from or containing at least one inorganic sorbent, min at least a binder, and optionally water and press tools at a pressure of at least about 70 MPa ver presses, in the mixture the weight ratio of dry Sorbent and the dry binder between about 4 and 0.7 and the water content of the mixture, determined at 160 ° C, is between about 8 and 20%; and the preserved green Press body at temperatures of at least about 500 ° C calci kidney until the total water content has been largely removed.

It has been found that especially before this procedure Partial pressed body with very good physical and chemical properties are available. Particularly advantageous Press bodies result from a mixing ratio of dry sorbent to binder in the starting mixture between about 1.5 and 1.

The desired water content of the mixture can be determined via the What content of the components (sorbent, binder) and / or  additional water can be set.

Zeolite A, which is preferably used as sorbent, is in powder Form available and has a water content of about 10 to 22%. The bentonite which is preferably used as the binder is as Powder with a water content of around 10 to 20% available. The bentonite used has a montmorillonite content of preferably <80%, based on the dry state. As Pressing aid is preferably a fatty acid salt divalent or trivalent metal, such as calcium, magnesium or Aluminum stearate used.

It was found that when the mixture was pressed to the Press body the best results can be achieved if the mixture has no major proportions, d. H. no more than about 15%, preferably not more than about 8%, and especially before attracts 0% of particles <250 µm, preferably <200 µm and especially containing preferably <150 microns, and the majority of Particles, d. H. at least 50%, preferably at least 60%, is larger than about 45 µm.

A preferred procedural measure is that Zeo lith and bentonite powder in the desired ratio with so much Water can be mixed so that the mixture can be granulated can. An intensive mixer is preferably used for this. The amount of water that needs to be added depends on Mixing ratio of zeolite and bentonite and the col loid chemical properties of the bentonite used in each case and can easily be determined routinely by a person skilled in the art. After granulating, the mixture is made up to a water level stopped from about 8 to 20% or dried, the Water content at 160 ° C is determined. Then that will Mixture to particle sizes <250 microns, preferably <200 microns, be particularly preferably <150 µm according to the above information kleinert.  

Surprisingly, it was found that when the Mix with the green compact to achieve the best results can be if the particles of the mixture are at least large partly have a largely spherical character, such as they z. B. can be obtained by spray drying. A special one the preferred process measure is therefore zeolite and bentonite powder using a high shear stirrer aggregates such as B. an Ultra-Turrax stirrer in water slurrying a pumpable suspension and after spray drying conventional processes. By appropriate Controlling the spray drying process can reduce the water content of the Mix to the preferred values between about 8 and 20% can be set (the water content is determined at 160 ° C). Adjusting the particle size distribution so that Mixture, as defined above, no major proportions of parties <250 µm, preferably <200 µm and particularly preferably < Contains 150 µm, as well as the majority of the particles larger than is about 45 microns, can also by appropriate control the spray drying process and any subsequent ones process steps known as such in the prior art, such as Deagglomeration, screening and sifting take place.

The molding of the mixture from the mixture is done by An apply a pressure of at least about 70 MPa. The before tensile pressure is about 100 to 1300 MPa. The pressing of the mixture can be found in commercially available automatic presses take place, the type of construction is known to the expert.

To ensure a smooth production of the pressed body It is important that the molded body is without back stood and easily detached from the pressing tools. This can by choosing appropriate surface-modified tools (with e.g. TiN or WC modified steel), exact setting treatment of the water content of the mixture and control of temperature temperature and humidity at the location of the pressing process be put. At low water content of the mixture  it is advantageous to have a relatively high absolute humidity cease activity, e.g. B. 60 to 80% relative humidity at about 25 to 35 ° C. With high water content of the mixture is a relatively low absolute humidity cheaper, e.g. B. 30 to 50% relative humidity at about 20 up to 30 ° C. Another preferred option is the order gene of an "anti-sticking agent", such as. B. magnesium or Calcium stearate, on the pressing tools after a predetermined th number of press cycles, e.g. B. after each or every two cycle. This can cause the compacts to stick to the Avoid pressing tools effectively.

The compacts are preferably at about 500 to 900 ° C calcined at about 650 ° C until constant weight is reached and the water content is largely removed.

It was also surprisingly found that the genesis of curvatures and curvatures in the calcination of the press body by applying pressure to the compact during of the calcination step can be largely suppressed.

According to a preferred embodiment, the application of Pressure on the compacts during the calcination by a set of a specially designed belt calciner acts, with a pressure on the bands on the Press body takes place. In principle, the pressurization on the pressed body during the calcination on any Wise, as long as the pressure applied on the one hand a curvature of the pressed body during the calcination effect is fully prevented and on the other hand the pressure is not to be reduced damage to the compact. Generally, a pressure between 10 and 30,000 Pa, in particular between 100 and 5,000 Pa can be applied. According to another preferred possibility a certain number of pressed bodies in tubes stacked, the z. B. best of stainless steel or ceramic hen. These tubes preferably have bores, which the  Allow water to escape during the calcination. because This enables quick and even drying. The entire stack inside the tube becomes one pressure exposed that is sufficient to bulge the compact during to suppress the calcination, but not to break it up Chen, gluing or sintering the compact during the this process step. Generally this pressure is between around 10 and 30,000 Pa, especially between 100 and 5,000 Pa. The calci according to the invention under pressure The wafers are flat and show no or only minimal ones Curvature or curvature, what for use in electrolumines devices is a prerequisite.

According to a further preferred embodiment, the Cal cination temperature door gradually approached or increased to the formation of cracks and cracks in the compacts Escaping water too quickly or unevenly prevent.

The compacts can also be calcined and vacuumed be cooled, which makes them capable of permanent Sorb gases like oxygen.

Furthermore, the molding pigment pigments, for. B. Fe ₃ O ₄ contain.

The invention also relates to the use of the first defined pressing bodies as inserts in electronic Devices or components, such as display devices, in particular in electroluminescent components, such as organic light emitting diodes (LED). They can also be damp sensitive liquid crystal display (LCD) devices be used.

These devices or components can be replaced by inorganic or ganic gases or vapors during the manufacture or during the  Use damaged in their function and have on due to their design, only a very small amount of space for one Sorbent.

These electronic devices or components (e.g. display pre directions in motor vehicles and mobile phones) are common exposed to strong vibrations, which is why it is important that the compacts do not break or crumble. on Because of its strength, the press is not necessary cover body with a gas-permeable film, whereby the manufacture of the electronic components is simplified.

Compared to BaO, there is a clear volume and cost re production of the electronic component. So they own Wafer mass-related higher sorption capacity and ge Speed for water vapor in the required temperature and Humidity area within an electronic component. In addition, when using BaO, it must be taken into account that in the hydration reaction an increase in volume of the material occurs around 100%; therefore there is additional within the component Lich volume for the expansion of the desiccant see and between BaO and the electroluminescent layer attach a water vapor permeable film that the Kon tact between the expanding and possibly crumbling prevents the desiccant and the layer. In contrast, the wafers show no volume when absorbing water vapor change and remain mechanically stable, so that the loading Provision of an additional expansion volume within the component and the application of a protective film can be.

BaO also has the disadvantage that it and its hy reaction products strongly basic; it also heats up it in the absorption of moisture locally and very strong it tends to come into direct contact with organic compounds Spontaneous combustion. This limits the choice of polymers for  the above-mentioned protective film on very expensive, e.g. B. Fluoropoly mere, and thus increases the cost of the component. Also kick when using BaO disposal problems because it is considered harmful chemical disassembly, reuse Formation and disposal of the individual parts of electronic construction sometimes very difficult.

However, the pressed bodies according to the invention can also be used otherwise Find use, e.g. B. as inserts in pharmaceutical packaging, because here only a limited volume for the inclusion of a tro means is available.

The compacts can be in any shape, e.g. B. be round, square, triangular or rectangular or else Bores and / or recesses included. The fiction moderate compacts are dust-free and wear-resistant. You can in usual press machines in large numbers per unit of time getting produced.

The invention is illustrated by the following examples:

Example 1 (comparison)

75.2 kg zeolite 4A (water content 20%), 23.8 kg bentonite (What content of 12%) and 1 kg of calcium stearate are combined in one sivmischer mixed for 2 minutes. Then water becomes one sharp increase in viscosity added and another 4 minutes mixed. The mixture is at 110 ° C to a water content dried by 12% and then granulated (Stokes Granu lator) and sieved (250 µm). 0.22 g of the material with a Particle size <250 µm are at a pressure of 69 MPa a round wafer. The green wafers are at 650 ° C calcined for three hours, excluding moisture cooled and packed airtight. The thickness of the wafers increases in the calcination by about 15 to 25%.  

product features

Thickness: 300 ± 50 µm
Moisture (after calcination): <1%
Production scrap: <90%
Drop test *: 100% break, wafer crumbles on the edge
* The so-called drop test serves as a measure of the compressive strength, whereby 100 calcined compacts (round disks with a diameter of 27 mm) are dropped from a height of 1 m with the flat side down. The percentage of broken test specimens is determined.

Example 2 (comparison)

57 kg zeolite 4A (water content 20%), 42 kg bentonite (water content 12%) and 1 kg calcium stearate are in one intensive mixer mixed for 2 minutes. Then water becomes one sharp increase in viscosity added and another 4 minutes mixed. The mixture is at 110 ° C to a water content dried by 12% and then granulated (Stokes Granu lator) and sieved (250 µm). 0.22 g of the material with a Particle size <250 µm are at a pressure of 69 MPa pressed a wafer. The green wafers become three at 650 ° C Calcined for hours, with the exclusion of moisture cooled and packed airtight.

product features

Thickness: 300 ± 50 µm
Moisture (after calcination): <1%
Production waste: 75%
Drop test: 80% break

Example 3

57 kg zeolite 4A (water content 20%), 42 kg bentonite (water content 12%) and 1 kg calcium stearate are in one intensive mixer mixed for 2 minutes. Then water becomes one sharp increase in viscosity added and another 4 minutes mixed. The mixture is at 110 ° C to a water content dried by 12% and then granulated (Stokes-Gra nulator) and sieved on a 250 µm sieve. 0.22 g of the mate rials with a particle size <250 µm are printed with one pressure of 72 MPa pressed into a wafer. The green wafers will be treated as in Example 2:

product features

Thickness: 300 ± 50 µm
Moisture (after calcination): <1%
Production scrap: <50%
Drop test: 60% break

Example 4

57 kg zeolite 4A (water content 20%), 42 kg bentonite (water content 12%) and 1 kg calcium stereate are in one intensive mixer mixed for 2 minutes. Then water becomes one sharp increase in viscosity added and another 4 minutes mixed. The mixture is at 110 ° C to a water content dried by 12%, then granulated (Stokes granules gate) and sieved on a 250 µm sieve. 0.22 g of the material with a particle size <250 µm with a pressure of 350 MPa pressed into a wafer. The green wafers are at Calcined at 650 ° C for three hours, with exclusion of moisture cooled and packed.  

product features

Thickness: 300 ± 50 µm
Moisture (after calcination): <1%
Production scrap: <25%
Drop test: 15% break
Sorption capacity * after one hour: 5.4% by weight
after 5 hours: 7.2% by weight
after 24 hours: 13.0% by weight
* The sorption capacity for water vapor is determined at 25 ° C in an atmosphere with a humidity of 10%.

Example 5

The operation of Example 4 was like with the deviation repeated that he calcined the green wafer in vacuo followed. The calcined wafers were essentially the same same product properties as the wafers of example 4, however showed additional absorption capacity for Sauer of about 5 ml / g (in a dry oxygen atmosphere certainly).

Example 6

56.5 kg zeolite 4A (water content 20%), 41.5 kg bentonite (What content 12%), 1 kg calcium stearate and 1 kg quebracho mixed in an intensive mixer for 2 minutes. Then there will be water added to a strong increase in viscosity and white mixed for another 4 minutes. The mixture is at a temperature of 110 ° C Dried water content of 12% and then granulated (Stokes granulator) and sieved (250 µm). 0.22 g of the material with a particle size <250 µm with a pressure of 200 MPa pressed into a wafer. The green wafers are at Calcined at 650 ° C for three hours, with exclusion of moisture  cooled and packed.

product features

Thickness: 300 ± 50 µm
Moisture (after calcination): <1%
Production scrap: <35%
Drop test: 10% break

Example 7

The operation of Example 4 was like with the deviation repeated that the pressure applied during pressing 1200 MPa is. The drop test showed 10% break. The committee was included <10%.

Example 8

The procedure of Example 4 was repeated with the difference that 54 kg of zeolite 4A, 40 kg of bentonite, 5 kg of Fe ₃ O ₄ and 1 kg of calcium stereate were used. The wafers obtained were colored dark and could be used as a contrast surface in an LED display.

Example 9

110.5 kg zeolite 4A (water content 20%), 76.0 kg bentonite (What content of 12%) and 1.9 kg of calcium stearate are in as much Water using a high shear agitator (Ultra-Turrax stirrer) slurried that a pumpable Sus pension arises. The suspension is sprayed in a manner dries that a powder with a water content of 9.2% (be determined by drying at 160 ° C) and a particle size  division of 0% <150 µm and 30% <45 µm. 0.17 g of this Materials become a wafer at a pressure of 190 MPa pressed with a diameter of 20 mm, the water vapor partial pressure in the ambient air of the pressing tools about 30 mbar is. The green wafers are applied using pressure calcined at 650 ° C for three hours. For this purpose, 300 green wafers in perforated stainless steel tubes (Height 120 mm, inner diameter 22 mm) stacked, and the sta pel exposed to a pressure of 2550 Pa. After the calcination was cooled and packaged with the exclusion of moisture.

product features

Thickness: 300 ± 50 µm
Vertical expansion (thickness + curvature): <350 µm
Moisture (after calcination): <1%
Production scrap: <5%
Drop test: <1%

Example 10

110.5 kg zeolite 4A (water content 20%), 76.0 kg bentonite (What content of 12%) and 1.9 kg of calcium stearate are in as much Water using a high shear agitator (Ultra-Turrax stirrer) slurried that a pumpable Sus pension arises. The suspension is sprayed in a manner dries that a powder with a water content of 12.6% (determined by drying at 160 ° C) and a particle size distribution of 0% <150 µm and 26% <45 µm. 0.17 g of this material become one with a pressure of 210 MPa Wafers with a diameter of 20 mm pressed, taking the water vapor partial pressure in the ambient air of the pressing tools about 17 mbar is. The green wafers are made using  Calcined pressure at 650 ° C for three hours. To do this, each 300 green wafers in perforated stainless steel tubes (Height 120 mm, inner diameter 22 mm) stacked, and the sta pel exposed to a pressure of 2550 Pa. After the calcination was cooled and packaged with the exclusion of moisture.

product features

Thickness: 300 ± 50 µm
Vertical expansion (thickness + curvature): <350 µm
Moisture (after calcination): <1%
Production scrap: <5%
Drop test: <1%

Example 11

110.5 kg zeolite 4A (water content 20%), 76.0 kg bentonite (What content of 12%) and 1.9 kg of calcium stearate are in as much Water using a high shear agitator (Ultra-Turrax stirrer) slurried that a pumpable Sus pension arises. The suspension is sprayed in a manner dries that a powder with a water content of 15.5% (determined by drying at 160 ° C) and a particle size distribution of 4% <150 µm and 8% <45 µm is created. 0.17 g this material becomes one with a pressure of 195 MPa Wafers with a diameter of 20 mm pressed, taking the water vapor partial pressure in the ambient air of the pressing tools about 12 mbar and the pressing tools periodically with magnesium be sprayed stearate. The green wafers are used pressure calcined at 650 ° C for three hours. To do this 300 green wafers each in perforated stainless steel tubes em steel (height 120 mm, inner diameter 22 mm) stacked, and the stack is subjected to a pressure of 2550 Pa. According to the Calci  nation was cooled with exclusion of moisture and ver grabs.

product features

Thickness: 300 ± 50 µm
Vertical expansion (thickness + curvature): <350 µm
Moisture (after calcination): <1%
Production scrap: <5%
Drop test: <1%

Example 12

57 kg zeolite 4A (water content 20%), 42 kg of a 50/50 Mi made from attapulgite and kaolin (water content 12%) and 1 kg Calcium stearate is ge in an intensive mixer for 2 minutes mixed. Then water will rise until a sharp rise in the vis added viscosity and mixed for a further 4 minutes. The mixture is dried to a water content of 12%, then granulated and sieved on a 150 µm sieve. 0.17 g of the mate rials with a particle size of <150 µm are produced with one pressure of 200 MPa pressed into a wafer. The green wafers will be calcined at 650 ° C for three hours, with moisture finally cooled and packed.

product features

Thickness: 300 ± 50 µm
Moisture (after calcination): <1%
Production waste: 25%
Drop test: 70% break

Example 13

An organic electroluminescent component 1 (square table, area 12.9 cm ² ), as shown in Fig. 1, is produced using a wafer (circular, diameter 27 mm) from Example 4. After the wafer 2 has been attached to the rear wall 3 of the component, this is attached to the glass substrate 5 of the component with the aid of an adhesive 4 and sealed as far as possible with the aid of an adhesive. At closing, a microscopic photograph (magnification 50 times) of the light-emitting part 6 (consisting of the anode 7 , the light-emitting layer 8 and the cathode 9 ) of the component is taken. This photograph shows no dark (non-luminous) spots that would indicate an attack on the cathode 9 .

The component is exposed to a temperature of 85 ° C and a relative humidity of 85% for 500 h. A microscopic photograph of the light-emitting part 6 of the component 1 is then taken again. A comparison of the two photographs shows that there are no dark spots that would indicate an attack on the cathode 9 .

Example 14 (comparison)

An organic electroluminescent component 1 such as Example 9 is produced using BaO. A water-permeable Teflon film is used as a cover for the BaO, which is attached to the rear wall 3 of the component with the aid of a thin double-sided adhesive tape. The amount of BaO is set so that the total mass of BaO, the Teflon film and the double-sided adhesive tape corresponds exactly to that of a wafer used in Example 9. Then, as described in Example 9, enlarged photographs of the light-emitting part are taken before and after storage for 500 h at 85 ° C. and 85% atmospheric humidity. A comparison of the two photographs shows a clearly recognizable growth of dark spots, which indicate an attack on the cathode 9 .

Claims (21)

1. Platelet-shaped pressed body (wafer) containing at least an inorganic sorbent and at least one binder, with a thickness of less than 700 µm, obtainable by pressing a mixture consisting of or containing the inorganic sorbent (sorbents) and the binder (s) tel, at a pressure of at least 70 MPa, being in a mixture the weight ratio of the dry sorbent (sorb tien) and the dry binder (s) between about 4 and 0.7 and the water content of the mixture, determined 160 ° C, is between about 8 and 20%; and calcining the obtained green compact at temperatures of at least about 500 ° C, until the water content is largely removed. 2. Press body according to claim 1, characterized in that the mixture of water and / or pressing aids, such as fatty acid Salts of a divalent or trivalent metal are added. 3. Press body according to claim 1 or 2, characterized in that that the calcination to constant weight or up to egg ner residual moisture content of <2% by weight, determined in the calculations temperature, is carried out. 4. Press body according to one of claims 1 to 3, characterized ge indicates that the inorganic sorbent is a natural or artificial zeolite. 5. Press body according to one of claims 1 to 4, characterized ge indicates that the binder has a smectic tone, preferably bentonite.   6. Press body according to one of claims 1 to 5, characterized ge indicates that the thickness of the wafer is about 200 to 400 microns is. 7. Press body according to one of claims 1 to 6, characterized ge indicates that the weight ratio of the tro sorbent to the dry binder between about 1.5 and 1 lies. 8. Press body according to one of claims 1 to 7, characterized ge indicates that the pressure is approximately 100 to 1300 MPa. 9. Press body according to one of claims 1 to 8, characterized ge indicates that a fatty acid salt is used as a pressing aid a 2- or 3-valent metal is used. 10. Press body according to one of claims 1 to 9, characterized ge indicates that it contains a tannic binder, preferably Quebracho, has been pressed. 11. Press body according to one of claims 1 to 10, characterized ge indicates that the mixture has no major proportions preferably not more than 15%, particularly preferably not more than 8%, and in particular 0% of particles <250 μm, preferably < Contains 200 microns and particularly preferably <150 microns. 12. Press body according to one of claims 1 to 11, characterized ge indicates that the majority of the particles, i. H. Minim at least about 50%, in particular at least about 60%, in the mixture is larger than about 45 µm. 13. Press body according to one of claims 1 to 12, characterized ge indicates that the mixture is mainly spherical contains kel.   14. Press body according to one of claims 1 to 13, characterized ge indicates that more than 50%, especially more than 75%, preferably more than 80% and in particular more than 98% of the Particles are essentially spherical. 15. Press body according to one of claims 1 to 14, characterized ge indicates that the mixture obtained by spray drying has been. 16. Press body according to one of claims 1 to 15, characterized ge indicates that it has been calcined under vacuum. 17. Press body according to one of claims 1 to 16, characterized ge indicates that the calcination is under pressure done on the compact. 18. Press body according to claim 17, characterized in that the calcination of the compacts under pressure in one go drilled tubes. 19. Process for the production of platelet-shaped pressed bodies (Wafer), characterized in that you have a mixture, best based on or containing the inorganic sorbent (s) (Sorbents) and the binder (s) at a pressure of pressed at least 70 MPa, the weight ratio in the mixture ratio of dry sorbent (sorbents) and (s) dry binder (s) is between about 4 and 0.7 and the Water content of the mixture, determined at 160 ° C, between about Is 8 and 20%; and calcining the obtained green Press body at temperatures of at least about 500 ° C to extensive removal of the water content. 20. The method according to claim 19, characterized in that one or more of those in one of claims 2 to 18 given components under the conditions specified there used.   21. Use of the compact according to one of claims 1 to 18 as an insert in electronic devices such as display devices tion, especially in electroluminescent components.