JP5222333B2 - Coating film drying method and apparatus - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a coating film drying method and apparatus, and in particular, a drying method for drying a long and wide coating film surface formed by coating various liquid compositions on a continuously running belt-like flexible support and Relates to the device.

  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.

  Regarding a drying method and apparatus for drying a long and wide coating film surface formed by coating various liquid compositions on a continuous belt-like flexible support, Non-Patent Document 1 describes a non-coated surface side with a roll. A drying method that blows and blows air from the air nozzle on the coating surface side, or a state where the support is floated by blowing air from the air nozzle on both the coated and non-coated surfaces, that is, the support rolls The non-contact type air floating drying method is described in which the drying is performed without contact with the air. As for this non-contact type drying method, there is a drying method using a string-winding type drying apparatus as disclosed in 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 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. There is a problem in that unevenness occurs, the evaporation rate of the solvent on the coating surface becomes non-uniform due to convection, so-called crushed skin (see Non-Patent Document 2), etc., and a uniform coating layer cannot be obtained. there were.

  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, or by using a high boiling point solution to cause a flow of the coating film surface immediately after coating due to drying air.

  However, the methods of Patent Document 2 and Patent Document 3 are effective in suppressing the inflow of non-uniform wind from the outside of the dryer, but if the wind speed is controlled so as not to disturb the coating film surface, the wind speed is greatly reduced. There is a need. 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 Document 4, Patent Document 5, Patent Document 6, and the like.

  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 Publication No. 1401041 US Pat. No. 5,168,639 US Pat. No. 5,694,701

"Coating and Drying Defects" by E.B.Gutoff, E.D.Cohen (Wiley-Intersciece, John Wiley & Sons, Inc) Yuji Ozaki, "Coating Engineering", pp293-294, Asakura Shoten, 1971

  However, in Patent Document 4, since the inlet and outlet of the support are limited to the upper part of the casing, the layout of the apparatus is greatly restricted, and it is difficult to incorporate it into an existing coating process. 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.

  In the layout improving method of Patent Document 5, it is difficult to adopt a configuration in which the distance from the coating device to the condensation / solvent recovery device is close, and this is insufficient for countermeasures against coating unevenness.

  Further, in the conventional solvent condensation / recovery method, the installation position of the condenser, the heating device, etc. in the condensation / recovery device, the set temperature, etc. are made constant, and the solvent is uniformly evaporated / recovered in the device. For this reason, it is convenient to set the same drying speed over the entire area in the apparatus, but it is not possible to select and dry the optimum conditions at each stage of the initial stage, middle stage, and late stage of drying. That is, it is difficult to control optimum conditions for suppressing coating unevenness, to control fine dry film quality, and to make drying efficient throughout the entire process.

  For example, in order to increase the drying speed, it is necessary to reduce the distance between the condensing surface of the apparatus and the coating film, but it is easily affected by the set distance accuracy. In addition, when the distance accuracy is improved, the manufacturing cost of the apparatus is generally greatly increased, which is not desirable.

  In addition, when it is desired to dry uniformly and quickly only in the initial stage of drying, the conventional method reduces the distance between the condensing surface of the device and the coating film over the entire length of the condensing / recovery zone. There was a considerable increase in costs.

  On the other hand, in order to keep the drying speed at the initial stage of drying low, it is necessary to lower the drying efficiency of the entire condensation / recovery zone. In this case, there is a problem that the total length of the condensation / recovery zone has to be increased.

  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 coating film drying method, a condensing plate, which is a plurality of plate-like members, is disposed in the dryer at a predetermined distance and in parallel with the strip-shaped flexible support. The distance from the conductive support is changed stepwise so that the downstream side in the running direction of the strip-shaped flexible support is separated from the coating film of the strip-shaped 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 disposed, and a condensing plate, which is a plate member, is disposed substantially parallel to the strip-shaped flexible support body at a predetermined distance, and the condensing plate and the strip-shaped flexible are disposed in the dryer. The unevenness that tends to occur immediately after coating is suppressed by changing the distance to the conductive support stepwise so that the downstream side in the running direction of the strip-shaped flexible support is separated from the coating film of the strip-shaped flexible support. And can be efficiently dried.

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

  The present invention is characterized in that the coating solution 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.

The conceptual diagram which shows an example of the coating and drying line 10 incorporating the drying apparatus with which the drying method and apparatus of the coating film of this invention are applied. The conceptual diagram which shows the other example of the coating and drying line 10 incorporating the drying apparatus with which the drying method and apparatus of the coating film of this invention are applied. The conceptual diagram which shows the further another example of the coating and drying line 10 incorporating the drying apparatus with which the drying method and apparatus of the coating film of this invention are applied. The conceptual diagram which shows the further another example of the coating and drying line 10 incorporating the drying apparatus with which the drying method and apparatus of the coating film of this invention are applied. The conceptual diagram which shows the further another example of the coating and drying line 10 incorporating the drying apparatus with which the drying method and apparatus of the coating film of this invention are applied. The conceptual diagram which shows the further another example of the coating and drying line 10 incorporating the drying apparatus with which the drying method and apparatus of the coating film of this invention are applied. The conceptual diagram which shows the further another example of the coating and drying line 10 incorporating the drying apparatus with which the drying method and apparatus of the coating film of this invention are applied. The conceptual diagram which shows the further another example of the coating and drying line 10 incorporating the drying apparatus with which the drying method and apparatus of the coating film of this invention are applied. The conceptual diagram which shows the example which applied the drying apparatus of the coating film of this invention 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

  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.

  FIGS. 1-8 is a conceptual diagram which shows each example of the coating / drying line 10 incorporating the drying apparatus with which the drying method and apparatus of the coating film of this invention are 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 drying device comprising a dryer 18 for condensing and recovering the solvent in the coating liquid of the coating film formed on the belt-like flexible support 12, and winding for winding up the product produced by coating and drying A take-off device (not shown) and a large number of guide rollers 22, 22... That form a conveyance path along which the belt-like flexible support 12 travels.

  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 (see FIGS. 1, 5, and 7), a wire bar coater (see FIGS. 2, 4, and 8), a roll coater, a gravure coater (see FIG. 6), and a slide hopper coating system (see FIG. 3). See), curtain coating method, etc. can be used.

  The application means 16 may be configured such that the application surface is on the upper side with respect to the horizontal direction as shown in FIGS. 1, 3, 5, and 7, or FIG. As shown in FIG. 6 and FIG. 8, the configuration may be a lower side with respect to the horizontal direction. Moreover, the structure which inclines with respect to a horizontal direction may be sufficient.

  As shown in FIG. 9, a dust removal facility 70 may be installed in front of the application 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 includes a condensing plate 20 which is a plate-like member provided substantially parallel to the belt-like flexible support 12 at a predetermined distance, and a side plate or the like suspended downward from the front and rear sides of the condensing plate 20. Composed. 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 a coating on the surface.

  In the dryer 18, the means for recovering the solvent condensed on the condensing plate 30, for example, provides a groove on the condensing surface of the condensing plate 30 and recovers 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 30 is inclined, the grooves may be provided in a direction in which the solvent can be easily recovered.

  In the example shown in FIG. 10, 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.

  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 provided with a condensing plate 20 that is a plate-like member substantially parallel to the belt-like flexible support 12 at a predetermined distance, and the distance between the condensing plate 20 and the belt-like flexible support 12. Can be changed in the running direction of the belt-like flexible support.

  As a structure which changes the distance of the condensation plate 20 and the strip | belt-shaped flexible support body 12 with the driving | running | working direction of a strip | belt-shaped flexible support body, as FIG. 1, FIG. 2 shows, several condensation plate 20, 20, Even when the distance between the condensing plate 20 and the strip-shaped flexible support 12 is changed stepwise, the condensing plate 20 is directed toward the running direction of the strip-shaped flexible support 12. A configuration in which the distance between the condensing plate 20 and the belt-like flexible support 12 is changed in a taper shape in the traveling direction of the belt-like flexible support 12 may be adopted (indicated not shown). In this case, the angle at which the condensing plate 20 is inclined toward the traveling direction of the strip-shaped flexible support 12 is preferably 30 degrees or less, more preferably 20 degrees or less with respect to the horizontal.

  In order to achieve the same effect as described above, the dryer 18 is provided with a plurality of condensing plates 20, 20, 20 along the traveling direction of the belt-like flexible support 12, and the condensing plates 20, 20 are connected to each other. As shown in FIG. 7, a configuration in which the partition plates 28, 28, 28 are disposed between the condenser plates 20, 20, and a plurality of box-shaped dryers 18, The condensing plates 20, 20, 20 are respectively provided on the 18, 18 and the box-shaped dryers 18, 18 are in close contact with each other, or the dryers 18, 18 are separated from each other.

  The dryer 18 and the condensing plate 20 do not necessarily have a linear shape as shown in FIGS. 1, 2, etc. For example, the arc-shaped dryer 18 and the condensing plate 20 as shown in FIGS. There may be. Further, a large drum may be provided and a condensing plate may be provided.

  In the example shown in FIGS. 5 and 7, the arc-shaped dryer 18 and the condensing plate 20 are brought close to the coating means 16 to improve the solvent recovery efficiency.

  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 within 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.

  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 condensation plate 20, or both. For example, cooling means (not shown) is disposed in the dryer, and heating means 24 and 24 are disposed on the opposite side of the dryer 18 with the belt-like flexible support 12 interposed therebetween (see FIGS. 4, 6, and 8). ).

  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.

  In the case where it is desired to heat the belt-like flexible support 12 and / or the coating film, a heater can be disposed 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.

  Moreover, the structure which changes the preset temperature of the heating means 24 and 24 with the running direction of the strip | belt-shaped flexible support body 12 can also be taken. For example, in FIGS. 4, 6, etc., the set temperature of the upstream heating means 24 is made lower than the set temperature of the downstream heating means 24 in the traveling direction of the belt-like flexible support 12. By setting in this way, drying unevenness can be further suppressed.

  Similarly, the structure which changes the preset temperature of the cooling means of the dryer 18 with the running direction of a strip | belt-shaped flexible support body can also be taken. In FIG. 4, FIG. 6, etc., the set temperature of the cooling means of the upstream dryer 18 in the traveling direction of the belt-like flexible support 12 is made different from the set temperature of the downstream cooling means. 4 and 6 are combined with a configuration in which a plurality of condensing plates 20, 20, 20 are disposed and the distance between the condensing plate 20 and the strip-shaped flexible support 12 is changed stepwise. ing.

  In addition, various modes such as a configuration in which the set temperature of the heating units 24, 24 is changed stepwise, a configuration in which the set temperature of the cooling unit of the dryer 18 is changed stepwise, or a combination of these can be adopted.

  It should be noted that conventional members are used for the feeding device, the guide roller 22, the winding device, etc. 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.

  When the coating film drying apparatus of the present invention is used in combination with a ventilation drying apparatus, the blower equipment for blowing wind can be greatly reduced. Therefore, costs such as air conditioning equipment costs can be greatly reduced, and the equipment can be made very compact.

  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]
[Example 1]
A dryer 18 for condensing and recovering the solvent in the coating liquid is disposed in the coating layer drying process in the optical compensation sheet production line shown in FIG. 9 to provide a suitable dryer for producing the optical compensation sheet. The structure and solvent condensation and recovery conditions were studied.

As shown in FIG. 9, the optical compensation sheet production line is performed, for example, by the following steps.
1) Delivery process 50 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 the liquid crystal layer is formed, or when a liquid crystal discotic compound having a crosslinkable functional group is used, the liquid crystal layer is irradiated with light (or heated). 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. 9, 62 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. 3, 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, the coating speed was 20 m / min, the coating amount was 5 cc / m ² , and then the product was 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 surface of the liquid crystal layer was irradiated with ultraviolet rays by an ultraviolet lamp while the film was continuously conveyed at 20 m / min. 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.

  The test was performed under the above-described process under six conditions. The conditions and results are described below.

(Test 1)
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 condenser plate 20 of the dryer 18 was 3 mm.

  As a result, a travel distance of 6 m was required to completely dry the coating film. There was no problem in coating film quality.

(Test 2)
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 0.5 mm.

  As a result, a travel distance of 1 m was required to dry the coating film. In the coating film, uneven drying occurred in the width direction, and alignment failure occurred.

(Test 3)
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 condenser plate 20 was divided into three zones. The three condenser plates 20 were all arranged with an inclination angle of 5 degrees so that the downstream side in the running 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 was 3 mm, 1.5 mm, and 0.5 mm, respectively, toward the downstream side in the traveling direction of the three condensing plates 20.

  As a result, a travel distance of 1.8 m was required to completely dry the coating film. There was no problem in coating film quality. That is, under these conditions, it was possible to achieve both shortening of the process length and good coating film quality.

(Test 4)
The heater temperature was 60 ° 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, a travel distance of 5 m was required to completely dry the coating film. There was no problem in coating film quality.

(Test 5)
The heater temperature was 60 ° C. and the condenser plate temperature was 15 ° 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, a travel distance of 2 m was required to completely dry the coating film. In the coating film, uneven drying occurred in the width direction, and alignment failure occurred.

(Test 6)
The heater temperature was 60 ° C. The dryer 18 was disposed so that the inlet was positioned 500 mm from the coating means 16. The condenser plate 20 was divided into three zones. Moreover, the condensing plate temperature of the three condensing plates 20 was 25 degreeC, 20 degreeC, and 15 degreeC, respectively toward the downstream of the running direction. 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, a travel distance of 0.8 m was required to completely dry the coating film. There was no problem in coating film quality. That is, under these conditions, it was possible to achieve both shortening of the process length and good coating film quality.

[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. 10, 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. 11, 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 those shown in FIG.

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

[Example 3]
Example in which drying means in combination with drying / condensing dryer (front stage side) and ventilation drying means (rear stage side) is disposed in the drying process of the photothermographic material production line, and conventional ventilation drying type This was compared with a comparative example in which only the drying means was provided.

  A coating solution for the photothermographic material to be coated on the belt-like flexible support was prepared as follows.

1) Preparation of silver halide grains After dissolving 22 g of phthalated gelatin and 30 mg of potassium bromide in 700 ml of water and adjusting the pH to 5 at a temperature of 35 ° C., 159 ml of an aqueous solution containing 18.6 g of silver nitrate and bromide An aqueous solution containing potassium and potassium iodide in a molar ratio of 92: 8 was added over 10 minutes by the controlled double jet method while maintaining pAg 7.7. Next, a control double jet method is used while maintaining an aqueous solution pAg7.7 containing 5476 g of silver nitrate, 10.5 μmol / liter of potassium hexachloroiridate, and 1 mol / liter of potassium bromide. Added over 30 minutes. Thereafter, the pH is lowered to agglomerate and precipitate for desalting treatment, 0.11 g of phenoxyethanol is added to adjust the pH to 5.9, pAg 8.2, silver iodobromide grains (iodine content core 8 mol%, average 2 mol%) And cubic grains having an average size of 0.05 μm, a projected area variation coefficient of 8%, and a (100) plane ratio of 90%).

  The silver halide grains thus obtained were heated to 60 ° C. and 85 μmol of sodium thiosulfate per mole of silver and 11 μmol and 15 μmol of 2,3,4,5,6 pentafluorophenyldiphenylphosphine selenide. A tellurium compound, 3.6 μmol of chloroauric acid, and 280 μmol of thiocyanic acid were added and ripened for 120 minutes, and then rapidly cooled to 30 ° C. to obtain a silver halide emulsion.

2) Preparation of organic acid silver emulsion 1.3 g of stearic acid, 0.5 g of arachidic acid, 8.5 g of behenic acid and 300 ml of distilled water were mixed at 90 ° C. for 40 minutes, and 1N aqueous sodium hydroxide solution was vigorously stirred. After adding 31.1 ml over 15 minutes, the temperature was raised to 30 ° C. Next, 7 ml of 1N phosphoric acid aqueous solution is added, 0.012 g of N-bromosuccinimide is added while stirring more vigorously, and the silver halide amount of the silver halide grains prepared in advance becomes 2.5 mmol. Was added as follows. Further, 25 ml of 1N aqueous silver nitrate solution was added over 25 minutes, and stirring was continued for 90 minutes. Thereafter, the solid content was separated by suction filtration, and the solid content was washed with water until the conductivity of the filtrate became 30 μS · cm. 37 g of a 1.2% by weight butyl acetate solution of polyvinyl acetate was added to the solid content thus obtained and stirred. The stirring was stopped and the mixture was allowed to stand. The oil layer and the aqueous layer were separated, and the aqueous layer was removed together with the contained salt. An oil layer was obtained. Next, 20 g of a 2.5 wt% 2-butanone solution of polyvinyl butyral was added to the oil layer and stirred. Further, 0.1 mmol of pyridinium perbromide and 0.18 mmol of calcium bromide dihydrate were added together with 0.7 g of methanol, and then 40 g of 2-butanone and 7.8 g of polyvinyl tyral were added to form a homogenizer. To obtain an organic acid silver salt emulsion (acicular grains having an average minor axis of 0.04 μm, an average major axis of 1 μm, and a variation coefficient of 30%).

3) Preparation of emulsion layer coating solution Each chemical was added to the organic acid silver salt obtained above so as to have the following amount per mole of silver. 10 mg sodium phenylthiosulfonate at 25 ° C., 68 mg dye 1, 30 mg dye 2, 2-mercapto-5-methylbenzimidazole 2 g, 4-chlorobenzophenone-2-carboxylic acid 21.5 g, 2-butanone 580 g, 220 g of dimethylformamide was added with stirring and left for 3 hours. Subsequently, 8 g of 5-tribromomethylsulfonyl-2-methylthiadiazole, 6 g of 2-tribromomethylsulfonylbenzothiazole, 5 g of 4,6-ditrichloromethyl-2-phenyltriazine, 2 g of a disulfide compound, 1,1-bis (2 -Hydroxy-3,5-dimethylphenyl) -3,5,5 trimethylhexane 160 g, tetrachlorophthalic acid 5 g, 1.1 g of fluorosurfactant, 2-butanone 590 g, methyl isobutyl ketone 10 g added with stirring did.

The emulsion layer coating solution prepared as described above was coated on a 175 μm polyethylene terephthalate support (strip-shaped flexible support) tinted with a blue dye so that silver was 2.3 g / cm ² . Then, after application, in the case of Examples, it was dried with a condensing / collecting dryer (front side) and ventilation drying means (back side), and then irradiated with ultraviolet rays to obtain a photothermographic material. On the other hand, in the case of the comparative example, the coating film was dried only with a ventilation drying type dryer, and then irradiated with ultraviolet rays to obtain a photothermographic material.

  The surface quality of the product produced by the method of the example was good. On the other hand, the surface property of the product manufactured by the method of the comparative example was poor due to the influence of wind unevenness.

[Example 4]
In the drying process of the hard coat film production line, an example in which a drying means combining a dryer that condenses and collects (front stage side) and a ventilation drying means (rear stage side) is disposed, and a conventional ventilation drying type This was compared with a comparative example in which only the drying means was provided.

A hard coat coating solution to be applied to the belt-like flexible support was prepared as follows.
1) Preparation of inorganic particle dispersion (M-1) The following reagents were blended in the following blending amounts in a ceramic-coated container to prepare a mixed solution.

・ Cyclohexane… 337g
・ Phosphate group-containing methacrylate (PM-2: Nippon Kayaku) ... 31g
Alumina (AKP-G015: manufactured by Sumitomo Chemical Co., Ltd., particle size 15 nm) ... 92 g
The obtained mixture was finely dispersed in a sand mill (1/4 G sand mill) at 1600 rpm for 10 hours. As a medium, 1400 g of 1 mmφ zirconia beads was used. After dispersion, zirconia beads were separated to obtain a surface-modified inorganic particle dispersion (M-1).

2) Preparation of coating liquid for active energy ray cured layer 97 g of methanol, 163 g of isopropanol, and 163 g of methyl isobutyl ketone were added to 116 g of 43 wt% cyclohexane dispersion liquid (M-1) of surface-treated alumina fine particles. 200 g of a mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate (DPHA, manufactured by Nippon Kayaku Co., Ltd.) was added to this mixed solution and dissolved. Further, 7.5 g of a photopolymerization initiator (Irgacure 184, manufactured by Ciba Geigy) was added and dissolved. The mixture was stirred for 30 minutes and then filtered through a polypropylene filter having a pore size of 1 μm to prepare a coating solution for an active energy ray cured layer.

  3) After the band-like flexible support (base film) was subjected to glow discharge treatment, the coating solution for active energy ray cured layer containing alumina was applied by a wire bar coating means so that the dry film thickness was 8 μm. And after application | coating, after drying with the dryer (front stage side) and ventilation drying means (back stage side) which condense and collect | recover in the case of an Example, the ultraviolet-ray irradiation was performed and the hardened layer was obtained. On the other hand, in the case of the comparative example, the coating film was dried only by a ventilation drying type dryer, and then irradiated with ultraviolet rays to obtain a cured layer.

  Next, in the drying process of the production line of the thick hard coat film, an example in which a drying unit that combines a dryer that condenses and collects (the front side) and a ventilation drying unit (the rear side) is disposed, and the conventional This was compared with a comparative example in which only a ventilation drying type drying means was provided.

  A thick film hard coat coating solution to be applied to the belt-like flexible support was prepared as follows.

1) Preparation of ring-opening polymerizable group-containing compound (K-1) 275 ml of methyl ethyl ketone (MEK) was stirred at 60 ° C. for 1 hour under a nitrogen stream, and then a polymerization initiator (V-65: manufactured by Wako Pure Chemical Industries, Ltd.) A polymerization initiator addition solution was prepared by adding 0.5 g of MEK in 8.3 ml. Thereafter, 50 g of glycidyl methacrylate was added dropwise over 2 hours, and after completion of the addition, the prepared polymerization initiator addition solution was added and reacted for 2 hours. Thereafter, the reaction was carried out at a reaction temperature of 80 ° C. for 2 hours, and after completion of the reaction, it was cooled to room temperature. The obtained reaction solution was added dropwise to 10 liters of hexane over 1 hour, and the precipitate was dried under reduced pressure at 35 ° C. for 8 hours to obtain a ring-opening polymerizable group-containing compound (K-1).

2) Preparation of curable composition 75 parts of trimethylolpropane triacrylate (ethylenically unsaturated group-containing compound), 25 parts of the prepared ring-opening polymerizable group-containing compound (K-1), radical polymerization initiator ( Irgacure 184, manufactured by Ciba Geigy Co., Ltd.) and a cationic polymerization initiator (UVI-6990: manufactured by Union Carbide Japan Co., Ltd.) were dissolved in 40 parts of a mixed solution of methyl isobutyl ketone / methyl ethyl ketone (1/5) and stirred for 30 minutes to cure. Sex composition was obtained. In addition, the polymerization initiator added 2.9 weight% of radical polymerization initiators and cationic polymerization initiators with respect to the total mass of the ethylenically unsaturated group-containing compound and the ring-opening polymerizable group-containing compound.

3) As a transparent belt-like flexible support (transparent substrate film), a polyethylene terephthalate film having a thickness of 188 μm was subjected to glow discharge treatment, and then the prepared curable composition was applied by an extrusion type coating method. After application, in the case of the examples, after drying with a dryer to be condensed / recovered (front stage side) and ventilation drying means (back stage side), UV irradiation is performed and heating is further performed at 120 ° C. for 10 minutes. A membrane hard coat film was obtained. On the other hand, in the case of the comparative example, the coating film was dried only with a ventilation drying type dryer, then irradiated with ultraviolet rays, and further heated at 120 ° C. for 10 minutes to obtain a thick hard coat film. The drying was performed at 120 ° C. for 2 minutes and the ultraviolet irradiation was performed at 750 mj / cm ² .

  The surface quality of the product produced by the method of the example was good. On the other hand, the surface texture of the product manufactured by the method of the comparative example caused a thickness unevenness that seems to be an influence of wind unevenness and became defective.

  DESCRIPTION OF SYMBOLS 10 ... Application | coating / drying line, 12 ... Strip | belt-shaped flexible support body, 16 ... Application | coating means, 18 ... Dryer, 20 ... Condensing plate, 22 ... Guide roller, 24 ... Heating means, 28 ... Partition plate

Claims (23)

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.
The dryer is provided with a condensing plate, which is a plurality of plate-like members substantially parallel to the belt-like flexible support at a predetermined distance, and the distance between the condenser plate and the belt-like flexible support is a belt-like shape. A method for drying a coating film, characterized in that the downstream side in the running direction of the flexible support is changed stepwise so as to be separated from the coating film of the strip-shaped flexible support.   A plurality of condensing plates are disposed in the dryer along the traveling direction of the belt-like flexible support, and the condensing plates are disposed apart from each other or a partition plate is disposed between the condensing plates. 2. A method for drying a coating film according to 1.   The method for drying a coating film according to claim 1 or 2, 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, wherein a distance between the coating unit and the dryer is 5 m or less.   The method for drying a coating film according to any one of claims 1 to 4, wherein a distance between the coating unit and the dryer is 0.7 m or less.   The coating film according to any one of claims 1 to 5, wherein a running 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. Drying method.   The coating film according to any one of claims 1 to 6, wherein a traveling speed of the belt-like flexible support is a speed at which the belt-like 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 8, 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 any one of claims 1 to 9, 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 1-10 which provided the cooling means in the said dryer.   The drying method of the coating film in any one of Claims 1-11 which provided the heating means on the opposite 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 12 which used the heating roll for the said heating means.   The method for drying a coating film according to claim 12, 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 0.01 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 0.01 to 100 mm.   The drying method of the coating film in any one of Claims 12-16 which changes the preset temperature of the said heating means with the running direction of a strip | belt-shaped flexible support body.   The drying method of the coating film in any one of Claims 11-17 which changes the preset temperature of the cooling means of the said dryer with the running direction of a strip | belt-shaped flexible support body.   The method for drying a coating film according to claim 17, wherein the set temperature of the heating means is changed stepwise.   The method for drying a coating film according to claim 18, wherein the set temperature of the cooling means of the dryer is changed stepwise. In an apparatus for drying a coating film, which is disposed in a subsequent stage following the coating means for coating the coating solution on the traveling belt-like flexible support, and which condenses and recovers the solvent in the coated coating solution.
The dryer is provided with a condensing plate, which is a plurality of plate-like members substantially parallel to the belt-like flexible support at a predetermined distance, and the distance between the condenser plate and the belt-like flexible support is a belt-like shape. An apparatus for drying a coating film, characterized in that the downstream side in the running direction of the flexible support is changed stepwise so as to be separated from the coating film of the strip-like flexible support.   Heating means is disposed on the opposite side of the dryer across the belt-like flexible support, and the set temperature of the heating means can be changed in the running direction of the belt-like flexible support. The apparatus for drying a coating film according to claim 21.   23. The coating film drying apparatus according to claim 21, wherein the dryer is provided with a cooling means, and a set temperature of the cooling means can be changed in a running direction of the belt-like flexible support. .

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