JP2007175703A - Method and apparatus for drying coating film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress drying unevenness and to efficiently dry a coating film formed by applying various kinds of liquid compositions on a continuously traveling flexible belt. <P>SOLUTION: A dryer 18 for condensing and recovering a solvent in a coating liquid directly after the various kinds of liquid compositions are applied on the continuously traveling flexible belt 12 by a coating means 16 is arranged in an apparatus for drying the coating film. A condensation plate 20 is arranged in parallel to the flexible belt 12 with a certain interval in the dryer 18. The condensation plate is inclined upward by ≥5° toward the traveling direction of the flexible belt. The traveling speed of the flexible belt is controlled so that the flexible belt reaches the dryer within 30 seconds after the application of the coating liquid by the coating means is completed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a coating film drying method apparatus, and more particularly to a drying method apparatus for drying a long and wide coating film surface formed by coating various liquid compositions on a continuously running belt-like flexible support. .

  This technology includes optical functional film sheets such as optical compensation sheets, solvent undercoats of photosensitive film materials, photothermographic materials, functional films containing finely structured particles such as nanoparticles, photographic films, and photographic prints. Used in the manufacture of paper, magnetic recording tape, adhesive tape, pressure-sensitive recording paper, offset plate materials, batteries, etc.

  EDGutoff, EDCohen's "Coating and Drying Defects" for drying equipment that dries long and wide coating surfaces formed by applying various liquid compositions to a continuous strip-like flexible support. (Wiley-Intersciece, John Wiley & Sons, Inc) supports the non-coated surface side with a roll, blows air from the air nozzle to the coated surface side, and dries the air on both coated and non-coated surfaces. It describes a non-contact type air-floating drying method in which air is blown from a nozzle to float the support, that is, the support is dried without contacting a roll or the like. About this non-contact type drying method, there is a drying method using a string-winding type drying apparatus as disclosed in the following Patent Document 1 as a method for efficiently using space and drying efficiently. .

  Usually, in the method of drying by blowing these winds (hereinafter referred to as ventilation drying method), the solvent contained in the coated surface is evaporated and dried by blowing the conditioned air on the coated surface. Although this ventilation drying method is excellent in drying efficiency, since the wind is applied directly to the coating surface or through a porous plate, a rectifying plate, etc., the coating surface is disturbed by this wind, and the thickness of the coating layer becomes uneven. Unevenness occurs or the evaporation rate of the solvent on the coating surface becomes uneven due to convection, so-called YUZU skin (see Yuji Harasaki, “Coating Engineering”, P293-294, Asakura Shoten, 1971) There was a problem that a uniform coating layer could not be obtained.

  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.

  When the liquid crystal is included in the coating film, not only the above-mentioned drying unevenness but also a problem such as a deviation in the orientation of the liquid crystal on the coating film surface due to the blowing wind occurs.

  As a method for solving these problems, Patent Document 2 discloses a configuration in which a dry dryer is provided immediately after coating. Here, a method of suppressing the occurrence of unevenness is disclosed by dividing the drying dryer and blowing and drying the divided portions from one end side in the width direction of the support body to the other end side while controlling the wind speed. Yes. Patent Document 3 discloses a method of installing a wire mesh instead of dividing a dryer for the same purpose.

  Further, in Patent Document 2, the viscosity of the coating solution is increased by increasing the concentration of the coating solution or adding a thickener to the coating solution. A method for preventing the occurrence of unevenness due to the leveling effect is disclosed by using a high-boiling point solution and a leveling effect even when a flow of the coating film surface immediately after coating occurs due to drying air.

  However, although the methods of Patent Documents 2 and 3 are effective in suppressing the inflow of non-uniform wind from the outside of the dryer, if the wind speed is controlled so as not to disturb the coating film surface, it is necessary to greatly reduce the wind speed. There is. As a result, the drying speed is greatly reduced, and it is necessary to increase the length of the drying dryer to cope with it. Therefore, the coating efficiency is deteriorated. Still, it is difficult to completely eliminate the influence of wind.

  In addition, the method of increasing the viscosity of the coating solution or using a high-boiling point solution, as described in Patent Document 2, results in loss of suitability for high-speed coating and an increase in drying time, resulting in extreme production efficiency. There was a problem of getting worse.

  Thus, in the ventilation drying method, particularly in the ventilation drying method in the case where the coating liquid contains an organic solvent, the drying of the coated surface is caused in the initial stage of drying, so that the method of drying without blowing air is patented. It is disclosed in Documents 4-6.

  That is, Patent Document 4 discloses a method of evaporating, collecting and drying a solvent in a coating solution without blowing air. This method is a method in which the inlet and outlet of the support are provided at the upper part of the casing, the non-application surface is heated in the casing to promote the evaporation of the solvent from the application surface, and condensation is caused on the condensation plate installed on the application surface side. In this method, the solvent is condensed to recover the solvent and dry the coating film.

Patent Document 5 discloses a method for recovering a solvent using a drum on an upper part of a support that runs horizontally. Furthermore, in patent document 6, the proposal about the layout improvement method of patent document 5 is made.
Japanese Patent Publication No. 48-42903 JP 2001-170547 A JP-A-9-73016 British Patent Application No. 1401041 US Pat. No. 5,168,639 US Pat. No. 5,694,701 (Japanese Patent Publication No. 11-511549)

  However, in Patent Document 4, since the entrance and exit of the support are limited to the upper part of the casing, there are great restrictions on the layout of the apparatus and it is difficult to incorporate it into the existing coating process. Also, in the example shown in Fig. 5, it is necessary to have a certain distance before entering the recovery dryer after coating, and it is necessary to reverse the base before entering the recovery dryer. It is difficult to suppress well.

  In Patent Document 5, since the distance from the coating surface to the condensation / solvent recovery drum varies in the coating direction, it is difficult to uniformly control the drying speed over the entire area in the casing, and the vicinity of the casing inlet and outlet Then, since the distance between the coating surface and the condensation / cooling drum is unnecessarily separated, another coating unevenness occurs due to the occurrence of natural convection.

  Patent Document 6 discloses a method for improving the layout. In this method, the condensation surface is disposed above the coating surface. Among these, it is described that the quality of the lower surface to which the coating solution is applied is poor, and that it is difficult to efficiently suppress coating unevenness immediately after coating in the configuration in which the belt-like flexible support is reversed after coating. However, in practice, 1) when the film thickness is thin, and 2) when an organic solvent is included, it cannot be said that it is generally bad.

  Further, it is stated that when the condensing surface is arranged on the upper side, it is necessary to use a force other than gravity, for example, a force such as a capillary force, so that the condensed liquid does not fall on the coating surface. . However, this method has a problem that a special device is required for liquid recovery, and the equipment becomes complicated and expensive.

  Similarly, although the above three types of prior arts have described in detail the method of recovering the solvent, there is no specific method related to a method for suppressing the occurrence of coating unevenness immediately after coating.

  Similarly, in the method of condensing and recovering the solvent and drying the coating film as in the above three types of prior arts, the drying efficiency is remarkably reduced as compared with ventilation drying. In addition, the above-described prior art does not describe an improved method for efficiently drying the coating film in the entire drying system.

  The present invention has been made in view of such circumstances, and in a long and wide coating film surface formed by coating various liquid compositions on a continuously running belt-like flexible support, immediately after coating. An object of the present invention is to provide a method and apparatus for drying a coating film that suppresses uneven drying and efficiently dries.

  In order to achieve the above-mentioned object, the present invention provides a dryer for applying a coating solution to a traveling belt-like flexible support by coating means and condensing and recovering the solvent in the coating solution at a running position immediately after coating. In the method for drying a coating film to be performed, a condensing plate, which is a plate-like member, is disposed in the dryer above the belt-like flexible support so as to be substantially parallel to the belt-like flexible support at a predetermined distance. At the same time, the condenser plate is inclined upward by 5 degrees or more in the running direction of the belt-like flexible support.

  According to the present invention, in a method of drying a long and wide coating film surface formed by coating various liquid compositions on a continuously running belt-like flexible support, the solvent of the coating solution is added immediately after the coating means. A condensing / recovering dryer is provided to suppress drying unevenness that is likely to occur immediately after coating, and can be dried efficiently.

  In particular, when an organic solvent is contained in the coating solution, or when the solvent of the coating solution is entirely composed of an organic solvent, the effect is great.

  In the present invention, the coating solution preferably contains 3% by mass or more of an organic solvent. In this case as well, by applying the present invention, drying unevenness that occurs immediately after coating can be suppressed and drying can be performed efficiently.

  The organic solvent means an organic compound having a property of dissolving a substance, such as aromatic hydrocarbons such as toluene, xylene and styrene, chlorinated aromatic hydrocarbons such as chlorobenzene and orthodichlorobenzene, and monochloro. Methane derivatives such as methane, chlorinated aliphatic hydrocarbons containing ethane derivatives such as monochloroethane, alcohols such as methanol, isopropyl alcohol and isobutyl alcohol, esters such as methyl acetate and ethyl acetate, ethyl ether, 1,4 -Ethers such as dioxane, ketones such as acetone and methyl ethyl ketone, glycol ethers such as ethylene glycol monomethyl ether, alicyclic hydrocarbons such as cyclohexane, aliphatic hydrocarbons such as normal hexane, aliphatic or aromatic This includes hydrocarbon mixtures.

  According to the coating film drying method and apparatus of the present invention, drying occurs immediately after coating on a long and wide coating film surface formed by coating various liquid compositions on a continuously running belt-like flexible support. The coating film can be dried uniformly while suppressing unevenness.

  In addition, the layout of the coating and drying process is not greatly changed, and further, the physical properties of the coating liquid and the type of solvent are not restricted, so that the coating liquid prescription means can be designed flexibly. It is also effective for energy saving and cost reduction.

  Furthermore, the flow in the coating film can be prevented, and the structure of the polymer and particle network in the coating film formed during drying can be formed very finely and uniformly.

  Hereinafter, preferred embodiments of a coating film drying method and apparatus according to the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a conceptual diagram showing an example of a coating / drying line 10 incorporating a drying apparatus to which a coating film drying method and apparatus of the present invention is applied. As shown in the figure, the coating / drying line 10 mainly applies a feeding device (not shown) for feeding a strip-shaped flexible support 12 wound in a roll shape, and applies a coating solution to the strip-shaped flexible support 12. Coating means 16, a dryer 18 for condensing and recovering the solvent in the coating film coating solution formed on the belt-like flexible support 12, and a winding device for winding the product produced by coating and drying (illustrated) And a large number of guide rollers 22, 22... That form a conveyance path along which the belt-like flexible support 12 travels. Further, a ventilation drying means for drying the coating film is provided downstream of the dryer 18 as necessary.

  The coating film formed on the strip-shaped flexible support 12 is on the upper side, the dryer 18 is disposed above the strip-shaped flexible support 12, and a condenser plate 20 described later is disposed on the strip-shaped flexible support. It is arranged to incline at a predetermined angle α of 5 degrees or more upward in the 12 traveling directions.

  2 and 3 are conceptual diagrams showing a reference example of the coating / drying line 10 incorporating a drying apparatus to which the coating film drying method and apparatus are applied.

  As shown in FIG. 2 and FIG. 3, the coating / drying line 10 mainly includes a feeding device (not shown) that feeds the strip-shaped flexible support 12 wound in a roll shape, and the strip-shaped flexible support 12. The coating means 16 for coating the coating liquid, the dryer 18 for condensing and recovering the solvent in the coating liquid of the coating film coated and formed on the belt-like flexible support 12, and the product manufactured by coating and drying are wound up. It is formed by a winding device (not shown) and a number of guide rollers 22, 22... That form a transport path along which the belt-like flexible support 12 travels. In this reference example, the coating film formed on the strip-shaped flexible support 12 is on the lower side, and the dryer 18 is disposed below the strip-shaped flexible support 12.

  As the belt-like flexible support 12, a resin film such as polyethylene, PET (polyethylene terephthalate), TAC (triacetate), paper, metal foil, or the like can be used.

  Various types of coating means 16 can be used. For example, a slot die coater, a wire bar coater, a roll coater, a gravure coater, a slide hopper coating method, a curtain coating method, or the like can be used.

  The application unit 16 may be configured such that the application surface is on the lower side with respect to the horizontal direction, or may be configured on the upper side with respect to the horizontal direction. Moreover, the structure which inclines with respect to a horizontal direction as FIG. 1 shows may be sufficient.

  FIG. 4 is a conceptual diagram showing an example of a production line of an optical compensation sheet incorporating the drying apparatus of FIG. 1 (the present invention), FIG. 2 (reference example), and FIG. 3 (reference example). Similarly, in the drying apparatus of the present invention, a dust removal facility 70 may be installed in front of the coating unit 16 or the surface of the belt-like flexible support 12 may be pretreated. For optical films and the like that require high quality with almost no dust, a high-quality coated and dried film can be obtained by simultaneously adopting these.

  The dryer 18 is suspended downward from the front and rear sides of the condensing plate 20 and a condensing plate 20 which is a plate-like member provided in parallel with the belt-like flexible support 12 at a predetermined distance (in FIGS. 2 and 3). It is composed of a side plate etc. Thereby, when the solvent in the coating liquid of the coating film is volatilized, the volatilized solvent is condensed on the condenser plate 20 and collected.

  The material used for the surface of the condenser plate 20 on which the solvent is condensed is not particularly limited, such as metal, plastic, wood, etc., but when the coating solution contains an organic solvent, the material is resistant to the organic solvent. It is desirable to use or to coat the surface.

  In the dryer 18, the means for collecting the solvent condensed on the condensing plate 20 is provided with a groove on the condensing surface of the condensing plate 20, for example, and collects the solvent using capillary force. The direction of the groove may be the traveling direction of the belt-like flexible support 12 or may be a direction orthogonal to this. When the condensing plate 20 is inclined, a groove may be provided in a direction in which the solvent can be easily recovered.

  In the example shown in FIG. 6, a bottle 20a for collecting the condensed solvent is provided below the right end of the condenser plate 20, and the solvent is collected through the bottle 20a. As described above, if the tub 20a is provided, the condensed solvent can be easily recovered. The position where the gutter 20a is provided is not limited to the illustrated example, and is provided at an appropriate position such as the downstream side or the side surface of the condenser plate 20 according to the configuration of the condenser plate 20. In any case, it is preferable to provide it at a position where it can be recovered by flowing down the solvent.

  Such a ridge 20a is also provided in the reference example in which the condensing plate 20 shown in FIG. 8 is disposed below the belt-like flexible support 12. Thus, when recovering the condensed solvent using the basket 20a, it is preferable that the condensing plate 20 is disposed with an inclination of 5 degrees or more with respect to the horizontal plane.

  In addition to the configuration in which the condensing plate 20 that is a plate-like member is employed for the dryer 18, a configuration that exhibits the same function, for example, a configuration that uses a perforated plate, a net, a scissors, a roll, or the like can also be employed. Moreover, you may use together with the collection | recovery apparatuses as shown by US5694701.

  The dryer 18 is preferably arranged as close as possible to the coating means 16 in order to prevent uneven drying of the coating film due to the occurrence of natural convection immediately after the coating liquid is applied. Specifically, it is preferable to arrange the inlet of the dryer 18 so that it is located within 5 m from the coating means 16, and arrange so that the inlet of the dryer 18 is located within 2 m from the coating means 16. It is more preferable that the inlet of the dryer 18 is disposed so as to be within 0.7 m from the coating means 16.

  For the same reason, the running speed of the strip-shaped flexible support 12 is preferably a speed at which the strip-shaped flexible support 12 reaches the dryer 18 within 30 seconds after coating by the coating means 16. It is more preferable that the support 12 has a speed that reaches the dryer 18 within 20 seconds after coating by the coating means 16.

  The larger the coating amount and the coating thickness of the coating solution, the more easily the unevenness occurs because the flow inside the coating film is more likely to occur. However, according to the present invention, even when the coating amount and the coating thickness are large, sufficient Effects can be obtained. If the thickness of the coating film is 0.001 to 0.08 mm, it can be dried uniformly and efficiently.

  If the running speed of the belt-like flexible support 12 is too high, the boundary layer near the coating film is disturbed by the accompanying wind, which adversely affects the coating film. Therefore, the running speed of the belt-like flexible support 12 is preferably set to 1 to 100 m / min, and more preferably set to 5 to 80 m / min.

  Since unevenness of the coating film is particularly likely to occur in the early stage of drying, it is preferable that the dryer 18 condenses and collects 10% or more of the solvent in the coating solution, and the remaining coating solution is dried by air drying means. What percentage of the solvent in the coating solution is condensed and recovered may be determined by comprehensively determining the influence on the drying unevenness of the coating film, production efficiency, and the like.

  In order to promote evaporation and condensation of the solvent in the coating solution, it is preferable to heat the belt-like flexible support 12 and / or the coating film, cool the condenser plate 20, or adopt both means. . For example, the cooling means is disposed in the dryer, and the heating means is disposed on the opposite side of the dryer 18 with the belt-like flexible support 12 interposed therebetween.

  In any case, it is desirable that the temperature is controlled in order to control the drying rate of the coating film. The condenser plate 20 can be controlled in temperature, and if it is desired to cool, it is necessary to install equipment for cooling. For cooling, a water-cooled heat exchanger system using a refrigerant or the like, an air-cooled system using wind, a system using electricity, for example, a system using a Peltier element, or the like can be used.

  When it is desired to heat the belt-like flexible support 12 or the coating film, or both, a heater can be provided on the anti-coating film side for heating. Moreover, it can also heat by arrange | positioning the conveyance roll (heating roll) which can be heated up. In addition, you may heat using an infrared heater, a microwave heating means, etc.

  When determining the temperature of the belt-like flexible support 12, the coating film, and the condensing plate 20, it should be noted that the evaporated solvent is condensed on a place other than the condensing plate 20, for example, on the surface of the transport roll. It is something that must be avoided. For this reason, this kind of dew condensation can be avoided by keeping the temperature of the part other than the condenser plate 20 higher than the temperature of the condenser plate 20, for example.

  The distance (interval) between the surface of the coating film and the surface of the condensing plate 20 of the dryer 18 needs to be adjusted to an appropriate distance in consideration of the drying speed of the desired coating film. Shortening the distance increases the drying speed, but is easily affected by the set distance accuracy. On the other hand, when the distance is increased, not only the drying speed is significantly reduced, but also natural convection due to heat occurs, resulting in drying unevenness. The distance between the surface of the coating film and the surface of the condenser plate 20 of the dryer 18 is preferably 0.1 to 200 mm, and more preferably 0.5 to 100 mm.

  The dryer 18 is not necessarily linear as shown in FIGS. 1 to 3, and may be, for example, an arc-shaped dryer. Further, a large drum may be provided, and a dryer may be disposed thereon.

  As a ventilation drying means used as necessary, a roller transport dryer method used as a conventional technique, supporting a non-application surface side with a roll and blowing air from an air nozzle on the application surface side, Both the coated and non-coated surfaces are blown from the air nozzle to float the support, that is, the support is dried without contacting the roll, etc. Non-contact air floating dryer method, non-contact drying It is a kind of system, and a drying device such as a string winding type that efficiently uses space and efficiently dries can be used. Any type of drying apparatus is common in that dried air is supplied to the surface of the coating film to dry the coating film.

  In addition, conventional members are used for the feeding device, the guide roller 22 and the winding device used in the coating / drying line 10 incorporating the drying device to which the coating film drying method and apparatus of the present invention is applied. These descriptions are omitted.

  According to the coating film drying apparatus of the present invention described in detail above, the coating film can be efficiently and uniformly dried while suppressing unevenness occurring in the coating film immediately after coating. In addition, the layout of the coating and drying process is not greatly changed, and further, the physical properties of the coating liquid and the type of solvent are not restricted, so that the coating liquid prescription means can be designed flexibly.

  That is, for example, by simply adding a dryer for condensing and recovering the solvent between the coating unit of the coating / drying apparatus including the existing ventilation drying apparatus and the ventilation drying apparatus, the configuration similar to that of the apparatus of the present invention can be obtained. As a result, the device can be modified at low cost.

  Further, the coating film drying apparatus of the present invention is effective in energy saving and cost reduction. That is, since the solvent other than water cannot be released into the atmosphere as it is in the evaporation gas generated in the coating / drying line, the evaporation gas needs to be liquefied and recovered, and a solvent gas recovery facility for that purpose is required. However, in the coating / drying line 10, the solvent can be directly recovered in a liquid state by a dryer that condenses and recovers a part of the coating liquid, so that the load on the solvent gas recovery facility can be reduced.

  Further, it was found that when the coating film drying apparatus of the present invention was used, extremely uniform drying was possible in the initial stage of drying, and the following unexpected effects were obtained. That is, in the conventional ventilation drying apparatus, since the influence that disturbs the coating film cannot be completely suppressed, the flow is generated in the coating film. However, when the apparatus of the present invention is used, the flow can be prevented, and It has been found that the polymer and particle network structure in the coating film formed during drying can be formed very finely and uniformly.

  As a result, the coating film is not only dried uniformly, but also the structure of the coating film becomes finer. For example, in the case of an optical film, a new additional function can be added.

  Moreover, it can be said that the drying apparatus of the coating film of this invention is very suitable for the drying of the functional film | membrane containing a nanoparticle etc., for example.

  Even when the coating film drying apparatus of the present invention is applied to a coating solution in which a solid content such as a polymer or particles is dissolved or dispersed, the same effect can be obtained. Rather, in a system containing particles or the like, the occurrence of drying unevenness greatly affects the dispersion distribution of particles in the coating film. Therefore, it is preferable to use this system in this system.

[Example 1]
A dryer 18 for condensing and recovering the solvent in the coating solution is disposed in the coating layer drying process in the optical compensation sheet production line shown in FIG. The structure and solvent condensation and recovery conditions were studied.

As shown in FIG. 4, the optical compensation sheet production line is performed, for example, by the following steps.
1) Delivery step 14 of the transparent film 12;
2) A forming step 52 of an alignment film forming resin layer in which a coating liquid containing an alignment film forming resin is applied to the surface of the transparent film and dried;
3) A rubbing step 54 in which an alignment film is formed on the transparent film by applying a rubbing treatment to the surface of the resin layer on the transparent film having the alignment film forming resin layer formed on the surface;
4) A liquid crystal discotic compound coating step 16 in which a coating liquid containing a liquid crystal discotic compound is coated on the alignment film;
5) A drying step 18 of drying the coating film and evaporating the solvent in the coating film;
6) A liquid crystal layer forming step 58 for heating the coating film to a discotic nematic phase forming temperature to form a discotic nematic phase liquid crystal layer;
7) The liquid crystal layer is solidified (that is, solidified by rapid cooling after forming the liquid crystal layer, or when a liquid crystalline discotic compound having a crosslinkable functional group is used, the liquid crystal layer is irradiated by light irradiation (or heating). Crosslinking) step 60;
8) A winding step 24 for winding the transparent film on which the alignment film and the liquid crystal layer are formed.

  In FIG. 4, 50 indicates a drying zone, 64 indicates an inspection device, 66 indicates a protective film, 68 indicates a laminating machine, and 70 indicates a slow dust facility.

  As shown in FIG. 4, the method for producing the optical compensation sheet was continuously performed continuously from the step of feeding the long transparent film to the step of winding up the obtained optical compensation sheet. On one side of a long film of triacetylcellulose (Fujitack, manufactured by Fuji Photo Film Co., Ltd., thickness: 100 μm, width: 500 mm), a long-chain alkyl-modified poval (MP-203, manufactured by Kuraray Co., Ltd.) ) A 5 wt% solution was applied and dried at 90 ° C. for 4 minutes, followed by rubbing to form an alignment film forming resin layer having a thickness of 2.0 μm. The conveyance speed of the film was 20 m / min.

  The triacetyl cellulose film has (nx−ny) × d, where nx and ny are the refractive indexes in two orthogonal directions in the film plane, nz is the refractive index in the thickness direction, and d is the thickness of the film. = 16 nm, {(nx-ny) / 2-nz} × d = 75 nm. The alignment layer forming resin layer was formed using a coating / drying apparatus.

  Subsequently, the surface of the resin layer was rubbed while the film having the obtained resin layer was continuously conveyed at 20 m / min. In the rubbing treatment, the rubbing roller was rotated at 300 rpm, and then the resulting alignment film was dedusted.

Next, the weight of the discotic compound TE-8 (3) and the weight of TE-8 (5) is transferred onto the alignment film while continuously transporting the obtained film having the alignment film at a speed of 20 m / min. A 10% by weight methyl ethyl ketone solution (coating solution) of a mixture obtained by adding 1% by weight of a photopolymerization initiator (Irgacure 907, manufactured by Nippon Ciba Geigy Co., Ltd.) to the above mixture in a ratio of 4: 1 by Using a coating machine, coating was performed at a coating speed of 20 m / min and a coating amount of 5 cc / m ² , and then passed through a drying and heating zone. Air was sent to the drying zone, and the heating zone was adjusted to 130 ° C. After 3 seconds from coating, it entered the drying zone, and after 3 seconds, it entered the heating zone. The heating zone passed in about 3 minutes.

  Subsequently, the alignment film and the liquid crystal layer were applied, and the film was continuously conveyed at 20 m / min, and the surface of the liquid crystal layer was irradiated with ultraviolet rays by an ultraviolet lamp. That is, the film that passed through the heating zone was irradiated with ultraviolet rays having an illuminance of 600 mW for 4 seconds by an ultraviolet irradiation device (ultraviolet lamp: output 160 W / cm, emission length 1.6 m) to crosslink the liquid crystal layer.

  On the other hand, as a comparative example, as shown in FIG. 5, the coating liquid is applied to the lower surface of the strip-shaped flexible support 12 by the coating means 16, and then the strip-shaped flexible support 12 is attached to the guide roller 22. , 22, and 22, and a configuration in which the coating liquid is applied to the dryer 18 so that the coating surface is the upper surface is employed. Other configurations were the same as those in the example.

  By the above steps, the test was conducted under the conditions of the following examples, reference examples and comparative examples. The conditions and results are described below.

(Example)
The configuration around the dryer 18 is the arrangement shown in FIG. In the dryer 18, a condensing plate 20, which is a plate-like member, is disposed above the belt-like flexible support 12 and at a predetermined distance from the belt-like flexible support 12. The inclination angle α was 15 degrees.

  The heater temperature was 85 ° C. and the condenser plate temperature was 25 ° C. The dryer 18 was disposed so that the inlet was positioned 500 mm from the coating means 16. The distance between the surface of the coating film and the surface of the condensation plate 20 of the dryer 18 was 1 mm.

  As a result, no problem occurred in the coating film quality.

(Reference example)
The configuration around the dryer 18 is the arrangement shown in FIG. In the dryer 18, a condensing plate 20, which is a plate-like member, is disposed below the belt-like flexible support 12 and at a predetermined distance from the belt-like flexible support 12.

  The heater temperature was 85 ° C. and the condenser plate temperature was 25 ° C. The dryer 18 was disposed so that the inlet was positioned 500 mm from the coating means 16. The distance between the surface of the coating film and the surface of the condensation plate 20 of the dryer 18 was 1 mm.

  As a result, no problem occurred in the coating film quality.

(Comparative example)
The configuration around the dryer 18 is the arrangement shown in FIG. In the dryer 18, a condensing plate 20, which is a plate-like member, is disposed below the belt-like flexible support 12 and at a predetermined distance from the belt-like flexible support 12.

  The heater temperature was 85 ° C. and the condenser plate temperature was 25 ° C. The dryer 18 was arranged so that the entrance was at a position 10 m from the coating means 16. That is, the position where the dryer 18 is disposed is not a traveling position immediately after application, but a position separated from the application unit 16 by a predetermined distance. The distance between the surface of the coating film and the surface of the condensation plate 20 of the dryer 18 was 1 mm.

  As a result, drying unevenness occurred in the coating film, and alignment failure occurred.

[Example 2]
In the drying process after the undercoat coating in the photosensitive cellulose acetate film production line, a dryer for condensing and recovering the solvent in the coating liquid in the present invention is disposed, and a conventional ventilation drying type dryer is disposed. The case was compared.

  In the production line using the dryer of the present invention shown in FIG. 6, the cellulose acetate dope is cast from the casting die onto the casting drum surface, and the film formed thereby is peeled off by the peeling roller. It is dried with hot air while traveling between the rolls in the pre-drying step.

  Next, an undercoat for a photographic light-sensitive material is applied and further dried with a dryer 18. When the residual solvent becomes about 10% or less, it is guided to a width regulating device (not shown), stretched in the width direction by 2 to 6%, and further cooled in a tension state and then wound up.

  The condenser plate 20 of the dryer 18 was divided into two zones. Further, the two condensing plates 20 were arranged at an inclination angle such that the downstream side in the traveling direction was separated from the coating film. The distance between the surface of the coating film and the surface of the condensing plate 20 of the dryer 18 is 0.8 mm on the inlet side of the condensing plate 20 on the upstream side and 2 mm on the outlet side toward the downstream side in the traveling direction. The plate 20 was 0.8 mm on the inlet side and 2 mm on the outlet side.

  Further, the length of the upstream condenser plate 20 was 2 m, and the length of the downstream condenser plate 20 was 4 m. The set temperature of the condenser plate 20 was 15 ° C. for all.

  The surface quality of the manufactured product was good.

  In the production line using the conventional ventilation drying type dryer shown in FIG. 7, the apparatus of the undercoat coating drying process is a normal ventilation drying type dryer. The other parts of the production line are the same as the configuration shown in FIG.

  The surface properties of the manufactured product were poor due to uneven drying in the undercoat.

The conceptual diagram which shows an example of the coating and drying line incorporating the drying apparatus to which the drying method and apparatus of the coating film of this invention are applied Conceptual diagram showing a reference example of a coating / drying line incorporating a drying apparatus to which the coating film drying method and apparatus are applied Conceptual diagram showing another reference example of a coating / drying line incorporating a drying apparatus to which the coating film drying method and apparatus are applied Conceptual diagram showing an example of applying a coating film drying apparatus to an optical compensation sheet production line The conceptual diagram which shows the example which applied the drying apparatus of the coating film of the comparative example to the production line of an optical compensation sheet The conceptual diagram which shows the example which applied the drying apparatus of the coating film of this invention to the production line of the photosensitive cellulose acetate film Conceptual diagram showing an example in which a conventional drying type dryer is applied to a photosensitive cellulose acetate film production line The conceptual diagram which shows the example which arranged the wrinkle further of the coating and drying line incorporating the drying apparatus to which the drying method and apparatus of the coating film of a reference example are applied

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Coating / drying line, 12 ... Strip | belt-shaped flexible support body, 14 ... Delivery apparatus, 16 ... Application | coating means, 18 ... Dryer, 20 ... Condensing plate, 22 ... Guide roller, 24 ... Winding device

Claims (17)

In the method for drying a coating film, a coating liquid is applied to a traveling belt-like flexible support by a coating means, and a dryer for condensing and collecting the solvent in the coating liquid is disposed at a traveling position immediately after coating.
A condensing plate, which is a plate-like member, is disposed above the belt-like flexible support above the belt-like flexible support at a predetermined distance and in parallel with the dryer. Inclined upward by 5 degrees or more toward the running direction of the flexible support,
The traveling speed of the strip-shaped flexible support is a speed at which the strip-shaped flexible support reaches the dryer within 30 seconds after coating by the coating means.   The method for drying a coating film according to claim 1, wherein the coating solution contains 3% by mass or more of an organic solvent.   The method for drying a coating film according to claim 1 or 2, wherein a distance between the coating means and the dryer is 5 m or less.   The method for drying a coating film according to claim 1, wherein a distance between the coating unit and the dryer is 0.7 m or less.   5. The coating film according to claim 1, wherein the running speed of the strip-shaped flexible support is a speed at which the strip-shaped flexible support reaches the dryer within 20 seconds after coating by the coating means. Drying method.   The method for drying a coating film according to claim 1, wherein the coating film has a thickness of 0.001 to 0.08 mm.   The method for drying a coating film according to any one of claims 1 to 6, wherein the belt-like flexible support has a running speed of 1 to 100 m / min.   The method for drying a coating film according to claim 1, wherein the belt-like flexible support has a running speed of 5 to 80 m / min.   The drying method of the coating film in any one of Claims 1-8 which provided the cooling means in the said dryer.   The drying method of the coating film in any one of Claims 1-9 which provided the heating means on the other side of the said dryer on both sides of the said strip | belt-shaped flexible support body.   The drying method of the coating film of Claim 10 which used the heating roll for the said heating means.   The method for drying a coating film according to claim 10, wherein an infrared heater or a microwave heating unit is used as the heating unit.   The method for drying a coating film according to claim 1, wherein a distance between the surface of the coating film and the surface of the dryer is 0.1 to 200 mm.   The method for drying a coating film according to claim 1, wherein a distance between the surface of the coating film and the surface of the dryer is 0.1 to 100 mm.   The drying method of the coating film in any one of Claims 1-14 which provided the basket which collect | recovers a solvent in the said dryer.   The drying method of the coating film in any one of Claims 1-15 which provided the groove | channel which collect | recovers a solvent in the said dryer. In an apparatus for drying a coating film, which is disposed in a subsequent stage following the coating means for coating the coating liquid on the traveling belt-like flexible support, and has a dryer for condensing and collecting the solvent in the coated coating solution.
The dryer is provided with a condensing plate, which is a plate-like member, at a predetermined distance above and in parallel with the strip-shaped flexible support above the strip-shaped flexible support. Is disposed at an inclination angle of 5 degrees or more upward in the running direction of the belt-like flexible support,
An apparatus for drying a coating film, wherein the belt-like flexible support travels at a speed at which the belt-like flexibility reaches the dryer within 30 seconds after coating by the coating means.

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