JP4406179B2 - Apparatus and process for uniformly drying products in web form produced by coating - Google Patents

Description

図２は、一定の含水量を調節する（水分補償域；２０）ための、本発明による装置を通る（移動方向に対して横方向）断面を示す。コーティングされた支持ウェブ（生成物ウェブ；１５）は、装置の内部空間を通って運ばれる。給送コンジット（２２）及び制御装置（２３；例えば、制御弁）を介して、入来する空気は空気湿潤器（２４）、加熱ウォーム（２５）、及び、任意には更なる制御弁（２６）を介して、スリットノズル（２７）を用いて水分補償域（２０）の内部空間（２１）に通される。水分で濃縮された、ノズルから放たれる新鮮な空気は、矢印の方向に生成物ウェブ（１５）上を通り、ウェブの横方向の縁を通る（細い矢印）。次に、処理後の空気は、換気扇（２９）を補助として排気部（２８）を介して下に示す矢印の方向に水分補償域から除去される。排気部（２８）は、同様に制御弁（３０）が設けられてもよい。更に、処理後の空気は、任意には、制御弁（３１）を用いてサイクルに戻され、（２２）を介して入る新鮮な空気と混合されてもよい。空気湿潤器（２４）を用いて、一定の値まで空気の含水量を調節することが可能である。
【００４０】
水分補償域として構成されていない、乾燥装置の乾燥域は、図２に示す構成と類似するが、空気湿潤器（２４）は設けられていない。
【図面の簡単な説明】
【図１】図１は、本発明による乾燥装置の側面図を示す図である。
【図２】本発明による装置の断面図である。
【符号の説明】
１，２，３，４，５，６，７，８，９，１０，１１，１２，１３，１４ 域
１５ 支持ウェブ
１６ 移動ローラ
１７ チャネル
２０ 水分補償域
２１ 内部空間
２２ 給送コンジット
２３ 制御装置
２４ 空気湿潤器
２５ 加熱ウォーム
２６ 制御弁
２７ スリットノズル
２８ 排気部
２９ 換気扇
３１ 制御弁[0001]
BACKGROUND OF THE INVENTION
The present invention particularly relates to an apparatus and process for uniformly drying a product in web form obtained by coating a thin film consisting essentially of organic raw materials and manufactured on an aqueous basis.
[0002]
[Prior art]
The films or coatings with which the invention is concerned are based on organic raw materials or mixtures of such substances. These are preferably water-soluble substances. Such organic raw materials include polymers such as polyvinyl alcohol, polyvinyl pyrrolidone, cellulose derivatives, polyvinyl acetate, polyethylene glycol, alginate, carrageenan, xanthan, gelatin, and other water-soluble polymers known to those skilled in the art, And mixtures and copolymers of these materials. If desired, such films or coatings may be filled with fillers such as mannitol, lactose, calcium phosphate, glucose, sorbitol, active substances such as drugs, aromatics, menthol, etc., sweeteners such as cyclamate. , Flavors such as glutamate, and in some cases other ingredients including volatile ingredients. These films may have adhesive properties.
[0003]
For various application purposes, a very thin film is required, ie a thickness of 10 to 500 μm, preferably 50 to 200 μm. A problematic property of such thin films is their high sensitivity to atmospheric humidity. At high atmospheric humidity, swelling is observed with these films, which increases the volume and can cause two or more overlying films to stick together. Conversely, such films tend to become brittle and break if the atmospheric humidity is too low.
[0004]
Such behavior can cause problems, especially with respect to the production of such films. In making a film, a procedure is typically used in which the coating composition or composition is applied as an aqueous solution or dispersion to a web-shaped sheet material or paper that functions as a carrier or support and then dried. Is done. During processing, the coated support material is passed through the drying oven without interruption. Area dryers used for this purpose are typically provided with nozzles for incoming air, which nozzles are the entire width of the product web, ie the direction in which the product web is moved. Air is sprayed laterally against Thereby, the edge area of the product web is in contact with the moving air than the central area of the product web.
[0005]
In particular in the case of films or other coatings produced on an aqueous basis, excessive drying of the edge areas of the coded product web (relative to the direction of movement of the product web) can occur. If the drying conditions are chosen so that the central area (in the machine direction, i.e. in the direction of movement) of the coated support web is dried to some extent, in many cases the edge area is then excessively dried ( Excessive drying). In the case of product webs treated with non-aqueous solvents, the effect is that the general purpose is to release all solvent residues from the product, ie, the solvent is removed to a level above 99%. Because it is not important. Thus, no “over-drying” occurs at the edges.
[0006]
The above-mentioned over-drying of the aqueous material in the edge region of the coded web-shaped support (= product web) leads to material shrinkage at the edge of the product web, possibly a composition of support and coating Since the degree of shrinkage of (or the dried film) may vary, the coating composition or the dried thin film may be separated from the support.
[0007]
The dryer configuration in the area where the incoming air nozzle is transverse to the direction of travel of the product web is non-uniform for films or other coatings produced on the basis of organic materials. Drying is caused, thereby causing differences in curing and crosslinking between the polymer chains. During further processing of the web material, different chemical or physical behaviors of the coated product occur depending on whether it is cut from the center of the product web or from the edge region.
[0008]
[Problems to be solved by the invention]
Accordingly, the present invention provides a process and apparatus that enables the production of the above types of films or coatings that have the same moisture content throughout the product web in both the transverse and longitudinal directions, avoiding the disadvantages described above. The purpose is to do. More specifically, it aims to allow the production of thin films with a consistent quality, especially with respect to water content.
[0009]
[Means for Solving the Problems]
The object is surprisingly the process of drying the thin film or coating according to claim 1, the process of manufacturing according to claim 2, the apparatus for setting a constant water content according to claim 9 and claim 12 and the embodiment of the invention described in the dependent claims.
[0010]
In the process of the present invention for drying a thin layer or film, the layer or film is preferably continuously passed through a drying apparatus having at least one drying zone and prepared in at least one drying zone during processing. Air having a water content corresponding to a certain water content of the film to be prepared or the layer to be prepared is supplied. Such a dry zone is called a moisture compensation zone.
[0011]
In this way, the more strongly dried edge region of the coated carrier web is wetted (or rewetted) when passing through such areas, thus resulting in a moisture content corresponding to the desired product moisture. . The water content in the central area of the coated film web is not increased during processing. In this way, it is realized that the same water content is generated in the edge region of the product web as in the central region of the product web. The film or coating thereby has uniform product properties across its surface. Leaving the film or coating from the support web in the edge region can be prevented.
[0012]
“Constant water content” is understood as meaning the desired water content of the product (film, coating) in the final state after manufacture (predetermined moisture: relative humidity 50-70%, preferably 70% ).
[0013]
The production of thin films or coatings is suitable for forming films or coatings, for example, polymers such as polyvinyl alcohol, polyvinyl pyrrolidone, cellulose derivatives, polyvinyl acetate, polyethylene glycol, alginate, carrageenan, xanthan, gelatin, And other water-soluble polymers known to those skilled in the art, as well as coating compositions containing organic materials such as mixtures of copolymers of these materials are first realized by the present invention. These materials are preferably completely or partially dissolved or dispersed in water. Other than water, other solvents such as methanol, ethanol, propanol, or solvent mixtures such as moisture-alcohol mixtures may be used.
[0014]
The coating composition further comprises various additives such as fillers such as mannitol, lactose, calcium phosphate, glucose, sorbitol and / or active substances such as drugs, aromatics, menthol, etc., cyclamate Such sweeteners, flavors such as glutamate, and in some cases other ingredients including volatile ingredients may be included.
[0015]
Thus, the resulting coating composition is then applied to a web-shaped support material using a casting method or a reverse coating method. As support material, a web or sheet of paper, plastic, metal, or a composite of two or more of these materials may be used. Furthermore, a web-shaped support material (so-called thermoformed blister paper) having a recess for receiving the coating material may be used.
[0016]
The product web may have, for example, a width of about 0.1 meter (m) to 2 m, with a width of 0.50 m to 1.6 m being preferred. The film or coating applied to the support layer is thin, that is, the total thickness thereof is preferably 10 to 500 μm, preferably 50 to 200 μm.
[0017]
The synthesis of the coated support material, i.e. the support material and the coating composition, is then transferred into a drying device (drying oven) and preferably moved continuously in this drying device.
[0018]
The drying device has at least one drying zone, but better still has at least two such zones through which the coated film passes.
[0019]
The process according to the invention for producing thin films or coatings, during drying, air having a moisture content corresponding to a certain moisture content of the film to be prepared is supplied in at least one drying zone called the moisture compensation zone. It is characterized by that.
[0020]
In the process of the present invention for drying a thin film or coating, drying is a constant moisture content of the film in which at least one surface area of the coating composition applied to the carrier is to be prepared during the first phase of drying. Drying is preferably realized by obtaining a moisture content corresponding to a predetermined moisture content) and obtaining a moisture content that is lower than a certain moisture content of the film in which at least one further surface area of the coating composition is to be prepared, Thus, at least one further surface area of the coating composition is dried more strongly than a surface area having a water content corresponding to a predetermined water content. During the subsequent phase of drying, at least one surface area of the coating composition applied to the support having a moisture content lower than the constant moisture content of the film to be prepared is brought to a constant moisture content of the film to be prepared. Obtaining the corresponding water content is realized. This is achieved using one or more moisture compensation zones as described above.
[0021]
Accordingly, a preferred embodiment of the drying process provides for the coating composition or film applied to the support to be passed through preferably at least two drying zones arranged in tandem, preferably by continuous feeding. .
[0022]
In this process, the film or layer is first passed through at least one drying zone and the film is dried to such an extent that its moisture content is reduced to a level at least corresponding to the constant moisture content of the film in the production state. After this stage of drying, a partial area of the film, i.e. at least one surface area, in particular the edge area, may still have a low water content. This means that overdrying can occur, particularly in the edge area, with respect to the machined or machined direction of the coated web.
[0023]
The coated carrier is then conveyed through at least one moisture compensation zone and the film is filled with air having a moisture content corresponding to a certain moisture content in its production state. In this way, it is realized that the over-dried edge area of the coated product web is rewetted and the water content in the process is adjusted to a predetermined value of the product. The coated product web, i.e. film or layer, thus obtains a uniform pre-determinable moisture over the entire surface without the individual areas being overdried or containing too much moisture.
[0024]
A further embodiment of the drying process is that the film or coated support is first passed through the preheating zone before the actual drying process starts, where the temperature is above room temperature, i.e. 25 It is raised to a level above 0, preferably 30 to 50 ° C. After this preheating zone, the support material provided with the coating composition reaches the drying zone as described above.
[0025]
Particular preference is given to embodiments of the drying process in which the film or coated support is continuously conveyed in a preheating zone and thereafter in at least three, preferably 4 to 16 drying zones. The total number of drying zones depends essentially on the drying profile, which is intended for each given case. At least one, preferably at least two drying zones are configured as moisture compensation zones. It is preferable that the moisture compensation area be placed between the drying areas.
[0026]
In addition, air and / or individual zones (preheating zone, drying zone, moisture compensation zone) using an open loop or closed loop control device to obtain a drying profile that matches the respective film or coating product. It is advantageous to adjust the temperature and / or water content of the fresh air at.
[0027]
The invention further comprises an apparatus for setting a constant water content of the coating composition applied to a support having a web shape. This device, which is a moisture compensation area, includes a drying area having an air supply section for sending fresh air and an exhaust section for exhausting the treated air, and the air supply section can adjust the moisture content of the air. Devices that can be adjusted or adjusted are provided. The adjustment of the water content of the fresh air supply can be performed automatically by the control loop.
[0028]
The effect of the aforementioned device is that the film or coating to be dried is carried through the zone so that during this process the film or coating is air at a defined temperature and with a defined moisture content. Charged with. For this purpose, the internal space of the device is provided with at least two air nozzles, preferably slit nozzles, through which the incoming fresh air adjusted to a specific water content is at least in the drying zone. The product web coated in the drying zone is moved into two spatial zones.
[0029]
The drying device according to the invention for uniformly drying a film or coating applied to a web-shaped support has at least three drying zones arranged in rows, and the web-shaped support to be dried through these zones Is carried further. The at least three zones are at least one preheating zone, at least one drying zone, and at least one drying zone called a moisture compensation zone. In the drying zone called the moisture compensation zone, A device is provided which makes it possible or possible to adjust the water content of the air to a constant value. It is also possible to provide two or more of the aforementioned areas in the drying apparatus. Thus, the drying device may have a range of 3 to 30, preferably 4 to 16, depending on the desired drying profile or product characteristics.
[0030]
For example, FIG. 1 shows a drying device having 14 zones (1) to (14). Here, the areas (1) to (3) function as a preheating area, for example, and the areas (4) to (14) function as a dry or moisture compensation area.
[0031]
In order to be able to adapt the drying conditions to the individual requirements, an open loop or a closed loop of the feed rate and / or temperature and / or moisture content parameters in at least one of the dryers or areas of the dryer It is advantageous if a device allowing control is provided.
[0032]
The process and apparatus according to the present invention enables the production of films or coatings of the type described herein that are characterized by consistent quality and moisture content that is constant over the entire surface. Furthermore, the disadvantage that the coating leaves the support web during the drying process is avoided.
[0033]
DETAILED DESCRIPTION OF THE INVENTION
Below, this invention is demonstrated using FIG.1 and FIG.2. The illustrated embodiments are merely examples and are not intended to limit the invention in any way.
[0034]
FIG. 1 schematically shows a side view of a drying device according to the invention. This device has 14 zones (1) to (14) arranged in tandem, through which the product web (= coated support web; 15) is passed. An arrow indicates a moving direction, and (16) indicates a moving roller.
[0035]
The individual zones (1) to (14) are preferably arranged in tandem at a short distance from each other so that only a narrow channel 17 is between the zones. In this way, it is realized that the desired temperature and moisture profile is maintained as precisely as possible.
[0036]
The newly coated support web (15) is fed into the dryer in zone (1) and exits the dryer in zone (14) in a uniformly dried state.
[0037]
Zones (1) through (14) may be preheated or dry zones where at least one dry zone is configured as a moisture compensation zone (see FIG. 2). For example, the areas (1) to (3) may be provided as a preheating area, the areas (4) to (9) as a dry area, and the areas (10) to (14) as a moisture compensation area.
[0038]
The temperature profile of zones 1-14 may preferably be configured as follows.
[0039]
[Table 1]

FIG. 2 shows a cross section through the device according to the invention (transverse to the direction of movement) for adjusting a constant water content (moisture compensation zone; 20). The coated support web (product web; 15) is carried through the interior space of the device. Via the feed conduit (22) and the control device (23; eg control valve), the incoming air is passed through an air wetting device (24), a heating worm (25), and optionally a further control valve (26). ) Through the internal space (21) of the moisture compensation area (20) using the slit nozzle (27). The fresh air released from the nozzle, enriched with moisture, passes over the product web (15) in the direction of the arrow and passes through the lateral edge of the web (thin arrow). Next, the treated air is removed from the moisture compensation area in the direction of the arrow shown below through the exhaust section (28) with the aid of the ventilation fan (29). The exhaust part (28) may be similarly provided with a control valve (30). Further, the treated air may optionally be returned to the cycle using a control valve (31) and mixed with fresh air entering via (22). It is possible to adjust the water content of the air to a certain value using an air humidifier (24).
[0040]
The drying area of the drying device, which is not configured as a moisture compensation area, is similar to the structure shown in FIG. 2, but the air wetting device (24) is not provided.
[Brief description of the drawings]
FIG. 1 is a side view of a drying apparatus according to the present invention.
FIG. 2 is a cross-sectional view of an apparatus according to the present invention.
[Explanation of symbols]
1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 Region 15 Support web 16 Moving roller 17 Channel 20 Moisture compensation region 21 Internal space 22 Feeding conduit 23 Controller 24 Air humidifier 25 Heating worm 26 Control valve 27 Slit nozzle 28 Exhaust part 29 Ventilation fan 31 Control valve

Claims (17)

Produced by applying the coating composition to be produced with an aqueous base to a support member, a process for drying the thin film to be moved drying apparatus in which at least two of the drying zone,
During the first phase of the drying, the coating composition applied to the support material passes first to at least one drying zone and has a water content corresponding to a certain water content of the film to be prepared. At least one surface area of the coating composition applied to the film, and at least one further surface area of the coating composition has a moisture content lower than a certain moisture content of the film to be prepared;
During the subsequent phase of drying, the coating composition applied to the support is at least one of the above-mentioned moisture compensation zones, which is supplied with air having a moisture content corresponding to a certain moisture content of the film to be prepared. The at least one surface area of the coating composition applied to the support material that passes through a further drying zone and has a moisture content below a certain moisture content of the film to be prepared is that of the film to be prepared. A process characterized in that it is carried out so as to obtain a water content corresponding to a certain water content . The process of claim 1, wherein the coating composition comprises an organic material . A process for drying a thin film produced by applying a coating composition produced on an aqueous basis to a support and moved in a drying apparatus having at least two drying zones,
The at least two drying zones are arranged in tandem, and in at least one drying zone called a moisture compensation zone, air having a moisture content corresponding to a certain moisture content of the film to be prepared is supplied,
The coating composition or the film each are on said support member, conveyed at least two drying zone in which is disposed in the tandem, the film is
a) the film is dried to such an extent that it first passes through at least one drying zone and the water content of the film is reduced to a level corresponding at least to a certain water content in the production state of the film; The typical area can have a lower water content,
b) A process characterized in that it subsequently passes through at least one further drying zone called the moisture compensation zone and the film is filled with air having a moisture content corresponding to a certain moisture content in its production state. Each of the film or the coated support is first passed through a preheat zone, the temperature of the film or the coated support is raised to a value above room temperature, and then the drying stage a) and The process of claim 3, wherein b) is received. Each of the film or the coated support material passes through a preheating zone and is then transported through at least three drying zones, wherein at least one of the drying zones is configured as a moisture compensation zone. A process according to any one of claims 1 to 4 . The film or the coated support material, respectively, the process of any one of claims 1 to 5, characterized in that passed through the two or more moisture compensation zone during drying. Air supply and / or fresh air temperature and / or moisture content using an open loop or closed loop control device to produce a drying profile adapted to the respective film or coating product in the individual zones process as claimed in any one of claims 1 to 6 but characterized in that it is adjusted. A drying apparatus having a plurality of drying zones arranged in a tandem manner through which a web-shaped support material is moved, and uniformly drying a film or a coating applied to the web-shaped support material,
At least three zones, namely
At least one preheating zone,
At least one dry zone; and
At least one dry area called moisture compensation area is arranged in tandem,
The drying device according to claim 1, wherein the moisture compensation area has an air supply section for sending fresh air provided with a device that enables or can adjust the moisture content of the air to a constant value. 9. The drying apparatus according to claim 8 , wherein there are two or more preheating zones and / or drying zones and / or moisture compensation zones. 3 to the drying apparatus according to claim 8, wherein it has a 30-pass the. At least one of the regions is controlled supply of air incoming and / or are provided with a device that allows for coordinated control of the temperature and / or moisture content of the fresh air of the respective region The drying apparatus according to any one of claims 8 to 10 , wherein 9. The drying apparatus according to claim 8, wherein the moisture content of the supplied air is adjusted using a control loop. At least two air nozzles, adjusted the supplied fresh air drying apparatus according to claim 8 or 12, wherein the emitting at least two spatial regions in the drying zone by the nozzle to a water content . The drying apparatus according to claim 13, wherein the air nozzle is a slit nozzle. 4. Process according to claim 3, characterized in that the partial area of the film is the edge area of the film. Each of the film or the coated support material passes through a preheating zone and is then carried through 4 to 16 drying zones, wherein at least one of the drying zones is configured as a moisture compensation zone. 5. Process according to any one of claims 1 to 4, characterized in that 10. A drying device according to claim 8 or 9, characterized in that it comprises 4 to 16 zones.

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