JP2012184874A - Drying device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating film drying device capable of suppressing drying irregularities while keeping an efficient drying capability in a film forming step requiring precise film thickness control.SOLUTION: In the coating film drying device which continuously applies a coating liquid to a traveling belt-like flexible support by a coating means and dries a coating liquid applied film, a slit plate having slits opened in a support width direction is continuously arranged in a support flowing direction, and adjacent slits are formed in such a way that their slit angles are alternately turned to an acute angle and an obtuse angle, with respect to a support vertical direction.

Description

  The present invention relates to a coating film drying apparatus for drying a coating film surface formed by applying various liquid compositions to a traveling flexible film.

  For a drying device that dries a long coating film surface formed by applying various liquid compositions to a continuously running flexible film, the non-coating surface side is supported by a roller and the coating surface side is air・ Drying device that blows and blows air from the nozzle, or air that blows from the air nozzle on both the coating and non-coating surfaces to float the support, that is, the support is dried without contacting the roller A contact-type air floating drying device is well known.

  Usually, in an apparatus for drying by blowing these winds, the solvent contained in the coated surface is evaporated and dried by blowing the conditioned air on the coated surface. Although such a wind blowing type drying apparatus is excellent in drying efficiency, the wind is applied directly to the coated surface or through a porous plate, a rectifying plate, etc .; There is a problem that unevenness occurs due to unevenness, the evaporation rate of the solvent on the coating surface becomes uneven due to convection, so-called crushed skin, and a uniform coating layer cannot be obtained. It was.

  In particular, when the coating solution contains an organic solvent, the occurrence of such unevenness is remarkable. The reason for this is that the organic film is sufficiently contained in the coating film at the initial stage of drying, and if the evaporation distribution of the organic solvent occurs at this stage, the temperature distribution and surface tension distribution on the coating film surface will result. This is because a flow such as so-called Marangoni convection occurs in the coating film surface. The occurrence of such unevenness becomes a serious coating defect.

  Also, as a method to prevent such unevenness, a method of blocking the disturbance wind by covering the entire coating film surface is used, but the evaporation solvent gas and the cause of the turbulence of the airflow on the coating film surface The coating unevenness often did not disappear due to the turbulence of the airflow generated when the drying air was mixed.

  Therefore, for example, a method as disclosed in Patent Document 1 is disclosed in order not to disturb the airflow while removing the solvent component that evaporates. In Patent Document 1, hot air is sent in parallel to the coating film formed on the base material in the drying apparatus and in the transport direction of the coating film, and the speed of the hot air that is the laminar flow is transported of the base material. Control is performed so that the relative speed is 0.1 m / second to 5 m / second with respect to the speed. However, with this structure, in order to keep the air flow on the substrate surface to be conveyed in a laminar flow, it is necessary to set the blowing air volume and angle with high accuracy, which is difficult at a practical conveyance speed.

Prior art documents are shown below.
JP 2002-340479 A

  As described above, the present invention provides a coating film drying apparatus capable of suppressing the occurrence of uneven drying while maintaining efficient drying capacity in a film forming process that requires precise film thickness control. It is.

  In order to solve the above-mentioned problems, the invention according to claim 1 of the present invention is the first aspect of the invention in which a coating liquid is continuously applied to a traveling belt-like flexible support by a coating means, In the drying apparatus for the coating film to be dried, a slit plate having a slit opened in the width direction of the support is continuously arranged in the support flow direction at a position close to the support on the coating film surface side, and the angle of the slit However, the drying apparatus is characterized in that adjacent slit angles are alternately acute and obtuse with respect to the vertical direction of the support.

  The invention according to claim 2 is the drying apparatus according to claim 1, further comprising a ventilation exhaust unit having supply air and exhaust air on the side opposite to the support body with respect to the slit plate.

  The drying apparatus according to claim 1 or 2, wherein the invention according to claim 3 is provided with a support heating means on the side opposite to the slit plate with respect to the support.

  The invention according to claim 4 is characterized in that the distance between the slit plate and the support is 1 mm to 50 mm, and the drying apparatus according to claim 1, claim 2, or claim 3.

  According to the present invention, the solvent component evaporated from the coating film surface gradually falls between the support and the slit plate due to its own weight, and naturally forms a flow from the slit having an obtuse and acute angle alternately. Thus, drying with rectified fresh air can be realized, and the occurrence of unevenness can be suppressed while maintaining the drying efficiency. In particular, the effect can be further exhibited by installing it in the initial drying portion that greatly affects the occurrence of unevenness.

  In addition, according to the present invention, the rectified fresh air can be controlled, and the drying efficiency can be stably maintained and unevenness can be suppressed.

  Further, according to the present invention, the support can be heated, and the drying efficiency can be increased while suppressing unevenness.

  In addition, according to the present invention, the occurrence of unevenness can be better controlled by keeping the distance between the slit plate and the support member as narrow as 1 mm to 50 mm.

It is sectional drawing which shows the outline of one Example of the drying apparatus of this invention.

  A drying apparatus according to the present invention will be described in detail below in accordance with an embodiment with reference to the drawings. FIG. 1 shows an embodiment of the present invention. The best mode for carrying out the present invention will be described in detail with reference to the drawings.

  As shown in FIG. 1, the drying apparatus of the present invention applies a liquid composition to one surface of the support 4 unwound from the unwinding 3 by the coating head 1 and then closes the slit plate near the coating surface. 5 are installed close to each other.

  The slit plate 5 opens in the width direction of the support at least beyond the coating width, and allows air to enter and exit the entire width direction. A plurality of slits of the slit plate 5 are continuously opened in the support body flow direction, and the opening angle alternately repeats an acute angle and an obtuse angle with respect to the support perpendicular direction.

  Here, the entire installation angle of the slit plate 5 is not horizontal but is installed with an angle, and is arbitrarily set depending on the type of application target and the type of solvent contained.

  A blower 6 equipped with exhaust and intake air may be installed on the opposite side of the slit plate 5 from the support, and the direction of blowing may be the support flow direction or the width direction.

Moreover, you may install the support body heating means 7 on the opposite side to a slit board with respect to a support body, As a support body heating system, a near infrared heater, a far infrared heater, a heat ray heater, a microwave heater, etc. are used. A non-contact heating method or a contact heating method in which the support is heated by holding a roll heated by hot water, steam, oil, hot wire or the like may be used.

The distance between the slit plate and the coated support is preferably set between 1 mm and 50 mm, and it is desirable that the distance can be selected depending on the application target.

  The drying apparatus according to the present invention can remove the evaporation solvent without adversely affecting the coating film surface and suppress the occurrence of slight drying unevenness. Therefore, the effect is most apparent in the initial stage of drying. Accordingly, the entire length of the drying apparatus is not entirely due to the drying apparatus of the present invention, and the drying apparatus of the present invention can be introduced only in the initial drying stage immediately after application to the substrate 4. In that case, you may introduce | transduce a well-known 2nd drying apparatus after the drying apparatus of this invention.

  As the second drying device, a method of applying a jet of increased temperature to the coating film formed on the substrate from a slit nozzle or punching metal may be introduced, or a quick return nozzle or substrate A system in which hot air is ejected from a nozzle that uses a parallel flow in the transport direction may be used. Moreover, you may provide a heating means not only from one side but from both sides. The use of any commercially available drying apparatus does not interfere with the effects of the present invention.

  Examples of the coating head 1 used in the present invention include devices such as die coaters, bar coaters, curtain coaters, extrusion coaters, roll coaters, dip coaters, spin coaters, and gravure coaters, but are not limited thereto. Is not to be done.

  The support 4 used in the present invention includes polyethylene terephthalate, polyethylene-2,6 naphthalate, cellulose diacetate, cellulose triacetate (triacetylcellulose), cellulose acetate propionate, polyvinyl chloride, polyvinylidene chloride, polycarbonate, polyimide. And plastic films such as polyamide, but are not limited thereto. In addition, paper or paper coated or laminated with α-polyolefins having 2 to 10 carbon atoms such as polyethylene, polypropylene, ethylene butene copolymer, and metal foils such as aluminum, copper, and tin are also included. However, it is not limited to these.

  The coating liquid used in the present invention contains a solvent, and any known coating liquid can be used as long as it forms a coating film on a substrate.

Examples of the solvent used in the present invention include alcohols such as methanol, ethanol, isopropanol, butanol and 2-methoxyethanol, ketones such as acetone, methyl ethyl ketone and methyl isobutyl, and esters such as methyl acetate, ethyl acetate and butyl acetate. , Ethers such as diisopropyl ether, glycols such as ethylene glycol, propylene glycol and hexylene glycol, glycol ethers such as ethyl cellosolve, butyl cellosolve, ethyl carbitol and butyl carbitol, aliphatic carbonization such as hexane, heptane and octane Examples include hydrogens, halogenated hydrocarbons, aromatic hydrocarbons such as benzene, toluene, and xylene, N-methylpyrrolidone, dimethylformamide, and the like, or one or a mixture of two or more There may, but is not limited thereto.

  With the drying apparatus as shown in FIG. 1, the coating film immediately after the coating liquid was applied to the substrate was dried, and it was confirmed whether or not drying unevenness occurred.

  A slit plate was disposed immediately after coating, a box was installed on the opposite side of the support with respect to the slit plate, and a blowing function was provided in the support flow direction. Moreover, the far-infrared heater was installed in the opposite side to the slit board with respect to the support body. Here, the total length of the slit plate was 2 m, and the distance between the support and the slit plate was 10 mm. The interval between the slits was 50 mm, the thickness of the slit plate was 30 mm, and the slit width was 5 mm. The slits were alternately arranged at an angle of 45 ° with respect to the vertical direction of the support. The wind speed of the blower was adjusted to about 1 m / min, and the exhaust side blower was controlled so that the pressure in the box became zero. Moreover, it adjusted so that the surface temperature of a far-infrared heater might be 100 degreeC, and it has arrange | positioned so that the distance from a support body may be 100 mm.

  As the coating solution, a coating solution of 50% toluene solvent and 50% acrylic resin was used, and a polyethylene terephthalate film having a thickness of 100 μm was used as the substrate. As coating conditions, coating was performed by die coating at a coating speed of 20 m / min.

  When coating was performed under the above-mentioned conditions, it was not possible to confirm unevenness that would cause a problem.

<Comparative example>
In the state where the drying apparatus of the present invention is not installed at all, application was performed under the same conditions as in the above example. As a result, it was possible to confirm unevenness in the coating film, and it was not possible to obtain a good product. It was.

  The drying apparatus of the present invention requires high-precision quality, such as optical films, electronic substrates, food packaging materials, medical packaging materials, etc., in the mass production field using a wet coating method that requires a drying process, This ensures stable production quality and contributes to lower costs and higher accuracy.

DESCRIPTION OF SYMBOLS 1 ... Coating head 2 ... Backup roll 3 ... Support body unwinding 4 ... Support body 5 ... Slit plate 6 ... Blower exhaust means 7 ... Support body heating means

Claims (4)

  In a coating film drying apparatus that continuously applies a coating solution to a traveling belt-like flexible support by a coating means and dries the applied coating film, it is supported at a position close to the support on the coating film surface side. A slit plate having slits opened in the body width direction is continuously arranged in the support body flow direction, and the slit angle is an acute angle and an obtuse angle alternately with respect to the support body vertical direction. A drying apparatus.   The drying apparatus according to claim 1, further comprising a blowing / exhausting unit having supply air and exhaust air on a side opposite to the support body with respect to the slit plate.   The drying apparatus according to claim 1, wherein a support heating unit is provided on the side opposite to the slit plate with respect to the support.   The drying apparatus according to claim 1, wherein the gap between the slit plate and the support is 1 mm to 50 mm.

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