EP1165208A1

EP1165208A1 - Drying device and method for producing the same

Info

Publication number: EP1165208A1
Application number: EP00922506A
Authority: EP
Inventors: Franz-Josef Becker; Robert-Peter Klein
Original assignee: LTS Lohmann Therapie Systeme AG
Current assignee: LTS Lohmann Therapie Systeme AG
Priority date: 1999-03-26
Filing date: 2000-03-09
Publication date: 2002-01-02
Also published as: DE19913761A1; DE19913761B4; AU4288100A; JP4996788B2; JP2002539932A; KR20020005632A; BR0009329A; CN1174792C; US6871419B1; KR100643971B1; WO2000057991A1; CN1345254A

Abstract

The invention relates to a flat and activable drying device for reducing the moisture content of a gas space surrounding said device and to a method for producing a device of this type. The inventive drying device contains a flat matrix with at least one regenerable drying agent.

Description

Drying device and method for its production.

description

The invention is directed to a device which is capable of reducing the moisture content or to ensure a defined moisture content of a closed gas space surrounding the device, to a method for producing such a device and to the use of this device

Such drying devices are known in the prior art. These can be desiccant-filled containers which are used, for example, for the dry storage of moisture-sensitive products

A desiccant bag is known, which is commercially available from Multiform Dessicant Ine, (Buffalo, New York) under the name Desimax ™. This type of desiccant bag consists of two bag walls that enclose an interior by means of weld seams on the edge of the bag walls. This interior contains a certain amount of

Desiccant, namely 4 A molecular sieve The bag walls themselves are at least partially permeable to water vapor

The disadvantage of such a system is that the certain, limited amount of the desiccant inside the bag corresponds only to a certain, limited moisture absorption capacity. If the amount of the desiccant is exhausted due to reaching the maximum absorption capacity for moisture (i.e. essentially water), the remains Desiccant bag ineffective Further moisture or water absorption is impossible and the guarantee of a constant, in particular reduced humidity in one Enclosed gas space surrounding the desiccant bag is not possible.

When processing such desiccant bags, therefore, the problem arises that long-term contact (for example, several minutes) with the ambient air, which generally contains more than 40% relative humidity, is to be avoided, since otherwise rapid exhaustion occurs, which de η desiccant bags for its further use, for example in the manufacture of packaging for moisture-sensitive products, makes it unusable. One solution to this problem is either

Processing in enclosed spaces with constant, greatly reduced relative humidity or the acceleration of the processing steps that are carried out during contact with the ambient air.

The desiccant bags are also not very versatile in terms of their usability with regard to different drying needs, because the amount of desiccant per bag (and thus the maximum moisture or water absorption capacity) is limited by the interior volume.

Another disadvantage of bags filled with desiccant is that the desiccant is present in solid, mostly granulated or powdered form within this bag. When filling, a very precise dosage of the desiccant is therefore required during the manufacturing process. When such a system is subjected to greater mechanical stress, however, there is also the risk that the bag wall or the weld seam on the edge of the bag will tear and the desiccant will escape. If the drying agent is not harmless or chemical reactions with the product to be stored under reduced or at a defined moisture content in a surrounding, closed gas space, such a desiccant bag also represents a certain safety risk for this product. According to DE 196 46 048, packaging for transdermal therapeutic systems with drying devices fixed on the inside is known. These packaging containing desiccants are multi-layer laminates. A layer containing desiccant can be attached to the composite of the other layers of the laminate using an adhesive layer. Like the desiccant bag already described, this packaging is subject to the rapid exhaustion of the moisture or water absorption capacity in the event of prolonged contact with normal ambient air. Normal ambient air means air that does not have a reduced relative humidity, but at least 40% relative humidity. The processing of these packaging laminates therefore also requires process steps in a room that is sealed off from the environment and / or work in a room with reduced air humidity.

The object of the invention is therefore to provide a device for reducing the moisture content of a closed gas space surrounding the device or for setting a defined relative air humidity, which avoids these disadvantages of the drying devices known in the prior art. In particular, the need for processing or prior storage in a closed gas space surrounding the device with reduced moisture content or processing under extremely time-limited conditions should be avoided.

The object is achieved by a drying device which contains a matrix with a desiccant contained therein and can be activated under technically sensible conditions. If necessary, the

Drying device contain a layer permeable to water vapor. With this layer the matrix can, if necessary, directly be covered. The desiccant is a regenerable desiccant. The drying device according to the invention and in particular the desiccant-containing matrix are preferably sheet-like. In a particular embodiment, the drying agent-containing matrix of the drying device has or is a pressure-sensitive adhesive layer.

Matrix in the sense of the invention means a carrier for the desiccant. In principle, inorganic and organic materials, in particular polymeric materials, are suitable as materials for this matrix. The matrix materials must have the ability to allow water molecules to penetrate and migrate within the material. On the other hand, this entering water must not lead to a complete dissolution of the polymeric material. Materials such as: polymeric substances such as acrylates, silicones, polyisobutylenes, SIS rubber, SBS rubber, SEBS rubber, polyvinylpyrrolidone, polyurethane, polyester, polyethylene, polyvinyl alcohol, polyamides, ethyl vinyl acetate, polyacrylic acid, collidon (copolymers of vinyl acetate and Vinyl pyrrolidone) and cellulose derivatives. In principle, all film-forming materials can be used. Mixtures of the organic polymer materials mentioned can of course also be used. The matrix is free of active pharmaceutical ingredients.

The matrix is preferably sheet-like. This means that the spatial configuration of this matrix in the three dimensions (height,

Length and width) in certain relationships. The height of the sheet-like matrix has a minimum value of approximately 50 μm and a maximum value of approximately 3 mm; the height of the sheet-like matrix is preferably between 200 and 500 μm.

The width or length of the sheet-like matrix are not critical parameters, but can meet the respective needs of practice be adjusted. The minimum value of the width for a practical handling of the sheet-like matrix can be seen as approximately 2 mm. The width of the sheet-like matrix is preferably between approximately 1 and approximately 50 cm, particularly preferably between approximately 2 and approximately 10 cm.

The length of the sheet-like matrix, like the width, can also be theoretically infinite. However, preferred lengths are also between about 1 and about 50 cm, particularly preferably between about 2 and about 10 cm, because of the easier handling.

In a preferred embodiment, the desiccant-containing matrix is elastic, which means the ability that the matrix can show a reversible change in shape. This improves certain properties of the matrix, such as softness, flexibility, flexibility and workability. It is necessary to add substances to the matrix that can influence this property. Such substances include plasticizers (elasticizers, plasticizers) for the respective matrix materials. Suitable plasticizers are, for example, polyethylene glycol, polypropylene glycol, glycerol, miglyol, propanediol, triglycide, esters such as diethyl phthalate, tributyl citrate, etc., which are optionally added to the matrix in such amounts until the desired elasticity is achieved. Of course, this depends in particular on the nature of the respective matrix material and the nature of the respective plasticizer, but the other components of the desiccant-containing matrix can also have certain influences on the elasticity, so that no exact limits can be given for the quantitative proportions. However, quantitative proportions of about 1 to 40% plasticizer are preferably contained in the matrix (based on the total weight of the matrix).

In a further embodiment, the desiccant-containing matrix can be pressure-sensitive, which means the ability that the matrix is permanently connected to a surface with a certain pressure by pressing it once. For this it may be necessary to add substances to the matrix that influence this property. Such substances include tackifiers (tackifiers, adhesive resins). Suitable tackifiers are known to the person skilled in the art, for example:

Rosin esters and hydrogenated esters of rosin, hydrocarbon resins, etc., which are optionally added to the matrix in such amounts until the desired pressure-sensitive adhesive property is achieved. The special matrix materials must be taken into account when choosing the amount of tackifier. The others can do this too

Components of the matrix containing the desiccant have an influence on the adhesive properties, so that no exact limits for the quantitative proportions can be specified. The amount ranges are therefore generally between about 5 and 70% tackifier in the matrix. Quantities of about 10 to 30% tackifier are preferably contained in the matrix (based on the total weight of the matrix).

In the embodiment in which the drying device contains a pressure-sensitive adhesive layer or even the desiccant-containing matrix itself is pressure-sensitive, the drying device expediently contains a release liner with an adhesive finish, which covers this pressure-sensitive adhesive layer and from which the drying device is removed before use. The materials for such carrier layers are known to the person skilled in the art, for example they can be foils containing substances such as polyethylene terephthalate, polyethylene, polypropylene, paper and their modifications.

As already mentioned, the drying device can additionally contain a layer which is permeable to water vapor. The matrix can optionally be covered with this layer. The water vapor permeable

Layer can be on one side or on both sides of the sheet-like matrix. As suitable materials for such water vapor permeable protective layer come z. B. cellulose in the form of film, fleece, paper, perforated film, etc. in question.

In a further embodiment, the drying device can also contain a support layer. It has the purpose of giving the drying device a higher dimensional stability. This can be the case, for example, when the matrix containing the desiccant is itself too flexible for practical handling, for example due to its very small thickness or relatively high elasticity. The support layer can optionally cover the matrix or even be identical to the layer permeable to water vapor. The support layer can be located on one side or on both sides of the sheet-like matrix. Suitable materials for such a support layer are materials known to the person skilled in the art, for example PET film, polyethylene, polypropylene, paper, nonwovens, etc.

If necessary, the drying device can also contain a protective layer which protects the desiccant matrix against mechanical stress from the outside, e.g. B. to protect abrasion or against leakage of desiccant. If necessary, this layer can be identical to the layer permeable to water vapor and / or the support layer. Suitable materials for the protective layer are materials known to the person skilled in the art, for example plastics such as polyethylene, polypropylene, paper, nonwovens, etc.

It is possible for the drying device to contain a layer which fulfills at least two of the technical functions of a water vapor permeable layer, support layer and protective layer.

If necessary, the desiccant-containing matrix can also be a

Moisture indicator included, the color of which depends on the water content and which thus indicates whether it is contained in the matrix Desiccant is still capable of further absorption of water. Such moisture indicators include, for example, copper (II) or cobalt (II) salts such as. B. CuSO or CoCI ₂ in question.

Desiccant in the sense of the invention means a substance that can absorb moisture, but especially water. The ability of these substances to absorb moisture can be based on a chemical or physical effect. In particular, regenerable substances are suitable for the invention, that is to say substances which are capable of releasing absorbed moisture (for example water) under certain conditions and thereby changing into a state which enables the substance to absorb moisture again. Suitable regenerable drying agents are CaSO (calcium sulfate, anhydrous gypsum, anhydrite), CaSO ₄ ^• _1/2 H ₂ O (hemihydrate), CaCl ₂ , Al ₂ O ₃ , CaO, Na ₂ SO ₄ , K ₂ C0 ₃ , CuSO ₄ , Mg (CIO ₄ ) ₂ , MgSO ₄ , silica gel (blue gel,

Silica gel), polyvinyl pyrrolidone (PVP) and mixtures of at least two of these substances.

According to the invention, these substances are used as solids or as a solution. The physical form does not play a special role, crystals, powders, amorphous solids, granules, rubbings, etc. come into question. However, the size of these solids in the desiccant is limited by the requirements for the thickness of the sheet-like matrix. An upper limit for the size of the solid particles is therefore approximately 200 μm, but particles with a grain size below 50 μm are preferably used. The minimum grain size of these particles is 1 μm.

The content of the desiccant in the matrix depends primarily on the desired moisture or water absorption capacity of the respective drying device and on the moisture or

Water absorption capacity of the special desiccant used. For example, if only a low water absorption capacity is required, the use of a desiccant with a low water absorption capacity in a low content in the desiccant matrix may be sufficient. A low desiccant content (in active form) in the matrix, for example, could represent about 0.5 to 5% of the total weight of the desiccant matrix. The thickness and the area of the desiccant-containing matrix can then possibly even be at the respective lower limits.

With a very high required water absorption capacity of the drying device, however, a desiccant-containing matrix with a relatively high desiccant content must be used, whereby the desiccant should also have a high water absorption capacity. Such a high desiccant content (in active form) can make up, for example, about 50 to 70% of the total weight of the desiccant matrix.

The drying device as such can be activated. This means that the object as a whole, but in particular, of course, the desiccant matrix, is stable to the conditions under which the desiccant contained in the matrix is regenerated. There must be no irreversible decomposition of individual components or permanent deformation, for example due to material softening. This is ensured by using materials which are resistant to elevated temperatures or heat radiation or microwaves.

The actual activation of the drying device or the desiccant-containing matrix can take place in various ways. The simplest type of activation is to store the desiccant-containing matrix under elevated temperature (for example 105, 110, 120, 140 or 170 ° C) for a certain period of time. The required one Storage duration the shorter the higher the selected temperature. Other options for activation can be the use of infrared radiation or microwave radiation.

As additional measures, a reduced external pressure (for

Example: 0.2 atm) and / or an artificially generated circulating air facilitate the selected activation conditions (for example: temperature, duration, radiation intensity). The use of these additional measures can also result in the fact that, in the case of activation at elevated temperature, this does not have to be above 100 ° C., the boiling point of the water under normal conditions, but may already be around 60 to 80 ° C.

When activated, the regenerable desiccant changes into its active form, in which it has the ability to absorb moisture or water.

It is clear that when choosing the activation method, which can also consist of a combination of different activation methods and additional measures, on the materials present in the drying device or in the matrix containing the drying agent and their properties (sensitivity to infrared or microwave radiation or increased Temperatures) must be taken into account. Otherwise, the materials of the desiccant matrix or the drying device may have to be adapted to the required activation conditions. The economy of the activation method and the material costs of the drying device may also need to be coordinated.

Concrete embodiments of a desiccant-containing matrix are flat-shaped systems, which include, for example, labels, films, tapes, rolls, stickers or discs. The advantages of the drying device according to the invention are, inter alia, that the desired moisture or water absorption capacity of the drying device by simply calculating its area and, if appropriate, its thickness and

Concentration of the desiccant in the matrix can be adapted to the particular need. This is due to the fact that the water absorption capacity of the drying device, with constant thickness and constant concentration of the drying agent in the matrix, is generally linearly related to its area. If the water absorption capacity of a drying device used is exhausted, further drying requirements could be supplemented by simply adding a further, easy-to-calculate area of the drying device according to the invention.

The drying device according to the invention is used to reduce the moisture content of a closed gas space surrounding the device or to maintain a defined, preferably reduced moisture content in a closed gas space surrounding the device. It can therefore be used in a method for reducing the moisture content of a closed gas space surrounding the device or for maintaining a defined, preferably reduced, moisture content in a closed gas space surrounding the device.

This gas space must be sealed gas-tight, so that there can be no exchange with air and the ambient air humidity contained therein. Such closed gas spaces can be, for example, airtight packaging of products. The possibilities for using the drying device according to the invention can therefore be found in the field of packaging moisture-sensitive objects, such as, for example, food, pharmaceuticals, diagnostics, medicines, moisture-sensitive chemicals, and biologically activatable material. It is preferred to use drying devices according to the invention within packaging for tablets, transdermal therapeutic systems and sheet-like pharmaceutical dosage forms for oral use.

If the drying agent contained in the matrix has the ability to molecules other than water (such as organic solvents such as ethanol, methanol, etc., odorants such as acetaldehyde, acetic acid etc., gaseous substances such as CS ₂ , NH ₃ , H ₂ S, etc. .) to bind, one use may be to reduce the content of such molecules in the gas space surrounding the drying device, or to keep this gas space largely free of such molecules.

Using the following examples, the production and the

Performance of the drying device according to the invention are explained.

example 1

347.84 g of 2-propanol are with

46.36 g of polyethylene glycol 400 and

81, 4 g of Kollidon 90 mixed and homogenized with stirring.

Then 127.5 g of calcium sulfate x 2H ₂ O are introduced and under high

Homogenizing stirring speed.

Claims

The resulting solvent-containing desiccant mass is coated on a 23 μ polyester film in such a way that a desiccant layer of 200 g / m2 results after evaporation of the solvent. The open side of the desiccant layer is laminated with a 26 g / m2 paper. Diecuts measuring 10 cm2 are produced and activated for 5 hours at 100 ° C. Example 2347.84 g of 2-propanol are mixed with 46.36 g of polyethylene glycol 400 and 81, 4 g of Kollidon 90 are mixed and homogenized. 127.5 g of calcium sulfate x 2H O are introduced into the homogeneous solution and homogenized at high stirring speed. The resulting solvent-containing desiccant mass is coated on a 23 μ polyester film in such a way that a desiccant layer of 200 g / m2 results after evaporation of the solvent. In a separate coating process, the commercially available Durotak 387-2287 pressure sensitive adhesive (manufacturer: National Starch & Chemical) is coated on a polyester film with an adhesive on one side in such a way that after evaporation of the solvent, a pressure sensitive adhesive layer of 20 g / m2 results. The open side of the pressure sensitive adhesive coating is laminated with the polyester side of the drying agent coating. Diecuts measuring 10 cm2 are produced and activated for 5 hours at 105 ° C. Example 3 Each five diecuts, which were produced by the processes described in Example 1 and in Example 2, are subjected to an experiment to determine the water absorption capacity. For this purpose, the diecuts were stored for at least 24 hours in a desiccator over supersaturated calcium nitrate solution (= 55% relative humidity). The water absorption is determined by weighing the diecuts at certain intervals. After 24 hours, the water absorption capacity of these special drying devices slowly decreased. The diecuts were reactivated under the conditions mentioned in Example 1 or Example 2 and subjected to a second experiment to determine the water absorption capacity. Table 1 shows the results of these experiments on the water absorption of the drying devices according to the invention. It can be stated that the water absorption is continuous over a period of at least 24 hours Table 1 -Water absorption (mg) X π = 5 after storage 1 hour 2 hours 4 hours 6 hours 24 hours Example 1 6.90 10.10 12 22 13.72 17.64 Example 2 4 74 7.28 9.38 1 1, 38 15.52 Water absorption after reactivation (mg) n = 5 after storage 1 hour 2 hours 4 hours 6 hours 24 hours Example 1 7.30 8.78 10.28 10.98 14.78 Example 2 6.62 8.28 10.30 11 14 15.18 The drying ability of the drying device according to the invention is therefore not limited to a one-time and / or short-term drying (as in the drying devices known in the prior art) However, experiment from example 3 also shows that the drying device according to the invention can be used to carry out a method for reducing the moisture content of a closed gas space and / or keeping a reduced moisture content of a closed gas space constant, which is characterized in that in a first step an activatable drying device can be carried out , which contains a flat-shaped matrix with at least one regenerable drying agent, is brought into the active state by activation, in a further step the activatable drying device is placed in the active state in the gas space, the moisture content of which is to be reduced and / or to be kept constant when the moisture content is reduced , in a further step said gas space is sealed airtight from the surroundings, and finally in a further step the activatable drying device in the active state via a longer period of z. B. absorbs moisture from the airtight gas space for at least one hour. Figure 1 shows various embodiments of the activatable drying device according to the invention. The various elements are explained in the attached legend. Shown are: 1 = activatable drying device, consisting of a desiccant-containing matrix. 2 = activatable drying device, consisting of a desiccant-containing matrix and a support layer. 3 = Activatable drying device, consisting of a release liner, a fixing device, a support layer and a desiccant matrix. = Activatable drying device, consisting of a release liner, a desiccant matrix and an underlying support layer. = Activatable drying device, consisting of a desiccant-containing matrix surrounded by two support layers. Activatable drying device, consisting of the composite of release liner, a fixing device and a desiccant-containing matrix surrounded by two support layers. claims

1 . Activatable drying device, characterized in that it contains a flat matrix with at least one regenerable drying agent contained therein.

2. Drying device according to claim 1, characterized in that it additionally contains a layer of a material permeable to water vapor.

3. Drying device according to claim 1, characterized in that it additionally contains a pressure-sensitive adhesive layer.

4. Drying device according to claim 1, characterized in that it additionally contains a protective layer.

5. Drying device according to claim 1, characterized in that it additionally contains a support layer.

6. Drying device according to claim 1, characterized in that it additionally contains a carrier layer (release liner).

7. drying device according to claim 1, characterized in that the desiccant matrix is elastic.

8. Drying device according to claim 1, characterized in that the desiccant matrix is pressure-sensitive adhesive.

9. Drying device according to claim 1, characterized in that the regenerable drying agent is selected from the group CaCl ₂ , CaSO ₄ , Al ₂ O ₃ , Na ₂ SO and polyvinylpyrrolidone.

10. Drying device according to claim 1, characterized in that the flat-shaped matrix contains a polymeric material.

11. Drying device according to claim 1, characterized in that the regenerable drying agent is contained in an amount between 0.5 and 70% in the sheet-like matrix (based on the total weight of the matrix).

12. Drying device according to claim 1, characterized in that the flat-shaped matrix contained therein has a height of between about 50 microns and 3 mm.

13. A method for producing a sheet-like drying device, characterized by the steps: a) producing a desiccant-containing matrix containing a regenerable desiccant in inactive form, with no additional measures to reduce the

Moisture content of the surrounding air space are carried out, b) optionally further steps for the production of a sheet-like drying device containing said drying agent-containing matrix, with these

Steps are also no additional measures to reduce the moisture content of the surrounding air space, and c) subsequent activation of the sheet-like drying device.

14. The method according to claim 13, characterized in that the activation is carried out by storing the sheet-like drying device at elevated temperature.

15. The method according to claim 13, characterized in that the activation by irradiation of the sheet-like

Drying device with infrared light.

16. The method according to claim 13, characterized in that the activation is carried out by irradiating the sheet-like drying device with microwaves.

17. The method according to claim 13, characterized in that the

Activation is supported by additional circulating air.

18. The method according to claims 13, characterized in that the activation is additionally supported by a reduced external pressure.

19. The method according to claim 13, characterized in that the

Activation by a combination of storage at elevated temperature and / or irradiation with infrared light and / or Irradiation with microwaves takes place, if necessary using the additional measures additional air circulation and / or reduced external pressure.

20. Use of a sheet-like, activatable drying device for the reduction or constant

Maintaining a certain moisture content of a closed gas space surrounding this device.

21. Use according to claim 20, characterized in that the gas space surrounding the device additionally contains a moisture-sensitive object.

22. Use according to claim 20, characterized in that the moisture-sensitive object is a food, a pharmaceutical, a diagnostic, a medicament, a chemical or a biologically activatable material.

23. Use according to claim 20, characterized in that the moisture-sensitive article is a tablet, a transdermal therapeutic system or a flat-shaped pharmaceutical dosage form for oral use.

24. Use of a sheet-like drying device for the removal of molecules of organic solvents and / or

Odorants from a gas space surrounding the device.

25. A method for reducing the moisture content of a closed gas space and / or keeping a reduced moisture content of a closed gas space constant, characterized in that a) in a first step an activatable drying device, which contains a flat-shaped matrix with at least one regenerable drying agent, by activation in the active state is transferred, b) in a further step the activatable drying device is placed in the active state in the gas space, the Moisture content is to be reduced and / or kept constant at a reduced moisture content, c) in a further step said gas space is sealed airtight from the environment, and d) in a further step the activatable drying device in the active state over a period of at least one hour of moisture from the airtight gas chamber.