JP2003170102A - Method and apparatus drying coating film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress drying unevenness and to efficiently dry the surface of a coating film formed by applying various kinds of liquid compositions on a continuously traveling flexible belt. <P>SOLUTION: A pre-heating means 32 for heating the flexible belt 12 is arranged at a traveling position before the various kinds of compositions are applied on the continuously traveling flexible belt 12 by a coating means 16 and a dryer 18 for condensing and recovering a solvent in a coating liquid is arranged at a traveling position in the coating surface side directly after the coating. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for drying a coating film, and more particularly to a long and wide coating film formed by coating various liquid compositions on a continuously running strip-shaped flexible support. The present invention relates to a drying method and device for drying a surface.

This technique is applied to optically functional film sheets such as optical compensation sheets, solvent undercoating of films for photosensitive materials, photothermographic materials, functional films containing fine structure particles such as nanoparticles, photographic films, It is used for the production of photographic printing paper, magnetic recording tape, adhesive tape, pressure-sensitive recording paper, offset printing plates, batteries, etc.

[0003]

2. Description of the Related Art A drying method and apparatus for drying a long and wide coating film surface formed by coating various liquid compositions on a continuously running strip-shaped flexible support is described in EBGutoff, ED.
Cohen's "Coating and Drying Defects" (Wiley-Inte
rsciece, John Wiley & Sons, Inc.) supports the non-coated surface side with a roll and blows air from the air nozzle onto the coated surface side to dry it. The non-contact type air floating drying method is described in which the support is floated, that is, the support is dried without coming into contact with a roll or the like. Regarding this non-contact type drying method, there is a drying method using a string-type drying device as disclosed in Japanese Patent Publication No. 48-42903 as a method of efficiently utilizing space and drying efficiently. .

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

Particularly, when the coating liquid contains an organic solvent, such unevenness is remarkable. The reason for this is
In the initial stage of drying, the coating film contains a sufficient amount of organic solvent, and if evaporation distribution of the organic solvent occurs at this stage, as a result, temperature distribution and surface tension distribution occur on the coating film surface, This is due to the flow of so-called Marangoni convection in the plane. The occurrence of such unevenness is a serious coating defect.

When the coating film contains liquid crystal, there is a problem that not only the above-mentioned drying unevenness but also the deviation of the alignment of the liquid crystal on the coating film surface due to the blowing air.

As a method for solving these problems, Japanese Patent Laid-Open No. 2001-170547 discloses a structure in which a drying dryer is provided immediately after coating. Here, a method for suppressing the occurrence of unevenness is disclosed by dividing the drying dryer and blowing the air into the divided portions while controlling the wind speed from one end side to the other end side in the width direction of the support, thereby suppressing the occurrence of unevenness. There is. JP 9-7301
6 discloses a method of installing wire mesh instead of dividing the dryer for the same purpose.

Further, in Japanese Patent Laid-Open No. 2001-170547, the viscosity of the coating liquid is increased by increasing the concentration of the coating liquid or adding a thickener to the coating liquid. The method of suppressing the flow due to the dry air and the method of preventing the occurrence of unevenness due to the leveling effect even when the flow due to the dry air of the coating surface immediately after coating occurs by using the high boiling point solution are disclosed. .

However, Japanese Unexamined Patent Publication No. 2001-170547 and Japanese Unexamined Patent Publication No.
The method of 9-73016 is effective in suppressing the inhomogeneous inflow of air from the outside of the dryer, but if it is attempted to control the air speed so as not to disturb the coating film surface, the air speed needs to be greatly reduced. As a result, the drying speed is significantly reduced, and it is necessary to increase the length of the dryer to cope with it. Therefore, the coating efficiency becomes poor. Moreover, it is still difficult to completely eliminate the influence of wind.

Further, as described in JP-A-2001-170547, the method of increasing the viscosity of the coating solution or using a high boiling point solution does not have suitability for high-speed coating or causes an increase in drying time. However, there was a problem that the production efficiency became extremely poor.

As described above, the ventilation drying method, particularly the ventilation drying method in the case where the coating liquid contains an organic solvent, causes nonuniform drying of the coated surface at the initial stage of drying, and therefore, a method of drying without blowing air. But GB1401041, US5168639, US
5694701 and the like. That is, GB1401041 discloses a method of evaporating and recovering and drying the solvent in the coating liquid without blowing air. In this method, the inlet and outlet of the support are provided on the upper part of the casing, and the non-coated surface is heated in the casing to accelerate the evaporation of the solvent from the coated surface, and the condensation plate is condensed on the coated surface side. In this method, the solvent is condensed to recover the solvent and the coating film is dried.

Further, US5168639 discloses a method of recovering a solvent by using a drum above a horizontally running support. Further, US5694701 proposes a method for improving the layout of US5168639.

[0013]

However, in GB1401041, since the inlet and outlet of the support are limited to the upper part of the casing, the layout of the device is largely restricted and it is difficult to incorporate it into the existing coating process. In addition, in the example shown in this abstract (Fig. 5), a certain distance or more is required before entering the recovery dryer after coating, and it is necessary to invert the base before entering the recovery dryer. It is difficult to efficiently suppress the unevenness of.

In US5168639, since the distance from the coating surface to the condensation / solvent recovery drum changes in the coating direction, it is difficult to uniformly control the drying speed over the entire area of the casing, and the casing inlet and outlet In the vicinity, the distance between the coating surface and the condensation / cooling drum becomes unnecessarily large, so that another coating unevenness occurs due to the occurrence of natural convection.

In the layout improvement method of US5168639,
It was difficult to adopt a configuration in which the distance from the coating device to the condensation / solvent recovery device was close, and it was insufficient as a countermeasure against coating unevenness.

Further, in the above-mentioned conventional solvent condensation / collection method, the support and the coating film are heated in order to accelerate the evaporation of the coating liquid, but it is efficient and compact equipment and the quality of the support is high. Could not be heated without damaging.

GB1401041 discloses a contact-type heating method using a large drum-shaped or planar heater. However, in the method of installing a large drum in the casing, the equipment becomes very large, which is a big limitation of the coating process layout, and when increasing the coating speed,
Since it is necessary to add a larger device, the equipment efficiency is poor. Further, when trying to drive the drum according to the coating speed, it was necessary to use a motor with a very large output.

It is necessary to collect the coating liquid on the drum surface, that is, on a curved surface. However, if the distance between the coating surface and the condensing surface is made constant in order to make the drying rate uniform, the condensing surface must also be a curved surface, which causes a problem of high manufacturing cost.

Further, as in the example of GB1401041, in the method of heating by bringing the support into contact with a flat heater surface,
In many cases, the support is scratched or the like, which adversely affects the quality.

In the example of US5168639, a non-contact type heating system is disclosed. In this case, however, since the heater is arranged on the lower side of the support over the entire length of the inside of the casing for solvent recovery, the heating at the time of transportation is performed. It was difficult to keep the distance between the heater and the support constant due to the influence of vibrations and wrinkles on the support, which resulted in uneven temperature.

US569470 also employs a similar non-contact heating method, and there is a concern that similar problems may occur.

As a means for suppressing the vibration of the support during conveyance and stably conveying the support, a large number of rolls in a state of being very close to the support are continuously arranged, and the pressure between the rollers is slightly reduced. A method for stabilizing the transportation of the support has been disclosed (JP 2000-19683, No. 2724398). In addition, as a method for drying a running support in a non-contact manner, the method disclosed in JP-A
9-310973 discloses a method using a steam type infrared heater.

However, satisfactory results have not been obtained using these means.

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

[0025]

In order to achieve the above-mentioned object, the present invention provides a coating film in which a coating solution is applied to a running belt-shaped flexible support by a coating device and the applied coating film is dried. In the drying method, the heating means for heating the strip-shaped flexible support is disposed at the traveling position before coating,
A dryer for condensing and collecting the solvent in the coating liquid is disposed on the coating surface side of the running position immediately after coating.

Further, according to the present invention, in a method for drying a coating film, which comprises applying a coating liquid to a running belt-shaped flexible support by a coating means and drying the applied coating film, a coating surface at a running position immediately after coating is applied. A dryer for condensing and recovering the solvent in the coating liquid is arranged on the side, and a heating means is arranged on the opposite side of the dryer with the strip-shaped flexible support being sandwiched therebetween.

According to the present invention, in a method for drying a long and wide coating film surface formed by coating various liquid compositions on a continuously running strip-shaped flexible support, the strip-shaped strip is formed at the running position before coating. By arranging a preheating means for heating the flexible support, a dryer for condensing and collecting the solvent in the coating liquid is arranged on the coating surface side at the running position immediately after coating to dry the coating film. In addition, it is possible to suppress unevenness in drying that tends to occur immediately after coating and to perform efficient drying.

In particular, the effect is great when the coating liquid contains an organic solvent, or when the solvent of the coating liquid is entirely composed of the organic solvent.

Further, the present invention is characterized in that the coating liquid contains an organic solvent in an amount of 3% by mass or more. In this case as well, by applying the present invention, it is possible to suppress unevenness in drying that occurs immediately after coating and to perform efficient drying.

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

[0031]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of a coating film drying method and apparatus according to the present invention will be described below in detail with reference to the accompanying drawings.

1 and 2 are conceptual views showing an example of a coating / drying line 10 incorporating a drying device to which the method and apparatus for drying a coating film of the present invention are applied.

As shown, the coating / drying line 10
Mainly includes a feeding device (not shown) for feeding the strip-shaped flexible support 12 wound in a roll shape, a preheating means 32 for heating the strip-shaped flexible support 12, and a strip-shaped flexible support 12. A coating means 16 for coating the coating liquid, a dryer 18 for condensing and collecting the solvent in the coating liquid of the coating film formed on the strip-shaped flexible support 12, and a ventilation drying for drying the coating film provided as necessary. Means (not shown), a winding device (not shown) for winding the product manufactured by coating and drying, and a large number of guide rollers 22, 22 forming a transport path along which the strip-shaped flexible support 12 travels. It is formed by and.

The strip-shaped flexible support 12 is made of polyethylene, PET (polyethylene terephthalate), TAC.
A resin film such as (triacetate), paper, metal foil or the like can be used.

The preheating means 32 may have various configurations, but as shown in FIGS. 1 and 2, a plurality of vertically arranged guide rollers 22, 22 ... Heaters 34, 3 are provided on both sides of the flexible support 12.
In general, 4 is arranged.

Further, as shown in FIG. 2, not only the heaters 34, 34 ... But also the hot air drying means may be used together with the preheating means 32.

As the coating means 16, various types 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 coating means 16 may have a structure in which the coating surface is on the lower side with respect to the horizontal direction as shown in FIG. 1, or may be on the upper side with respect to the horizontal direction. May be Moreover, as shown in FIG. 2, it may be configured to be inclined with respect to the horizontal direction.

The coating means 16 preferably has a temperature control means for controlling the temperature of the coating liquid. If the temperature of the coating liquid can be controlled by the coating means 16, the unevenness of drying that occurs immediately after coating can be suppressed and the coating film can be efficiently dried together with the preheating means 32.

As shown in FIG. 5, the coating means 16
The dust removing equipment 70 may be installed in the previous stage, or the surface of the strip-shaped flexible support 12 may be pretreated. In the case of an optical film or the like that is required to have a high quality with almost no dust, a high quality coating and dry film can be obtained by using these at the same time.

The dryer 18 is a condensing plate 30 which is a plate-like member provided in parallel with the belt-shaped flexible support 12 at a predetermined distance, and vertically extends downward from the front and rear sides of the condensing plate 30 (or. It is composed of a side plate and so on. Thereby, when the solvent in the coating liquid for the coating film is volatilized, the volatilized solvent is condensed and collected on the condenser plate 30.

The material used for the surface of the condensing plate 30 for condensing the solvent is not particularly limited to metal, plastic, wood, etc., but when the coating liquid contains an organic solvent, it is resistant to the organic solvent. It is desirable to use certain materials or to coat the surface.

In the dryer 18, the means for collecting the solvent condensed on the condensing plate 30 is, for example, provided with a groove on the condensing surface of the condensing plate 30 and recovers the solvent by utilizing the capillary force. The direction of the groove may be the traveling direction of the strip-shaped flexible support 12 or the direction orthogonal thereto. When the condensing plate 30 is inclined, the groove may be provided in the direction in which the solvent can be easily collected.

In the example shown in FIG. 6, a gutter 30a for collecting the condensed solvent is provided below the right end of the condensing plate 30, and the solvent is collected through the gutter 30a.

The dryer 18 has a condensing plate 30 which is a plate-shaped member.
In addition to the configuration adopting (1), a configuration having the same function, for example, a configuration using a perforated plate, a net, a cage, a roll or the like can be employed. It may also be used in combination with a recovery device as shown in 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 coating the coating liquid. Specifically, the inlet of the dryer 18 is the coating means 1
It is preferable to arrange it so as to be within a position of 6 to 5 m, and it is more preferable to arrange so that the inlet of the dryer 18 is within a position of 2 m from the coating means 16, and the inlet of the dryer 18 should be arranged. Most preferably, it is arranged at a position within 0.7 m.

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 speed reaches the dryer 18 within 20 seconds after coating.

As the coating amount and the coating film thickness of the coating liquid are larger, unevenness is more likely to occur because the flow inside the coating film is likely to occur, but according to the present invention, the coating amount and the coating film thickness are large. Even in this case, a sufficient effect can be obtained. When 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 strip-shaped flexible support 12 is too high, the boundary layer near the coating film is disturbed by the entrained air,
It adversely affects the coating film. Therefore, the running speed of the strip-shaped 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 at the initial stage of drying, it is preferable that the dryer 18 condense and recover 10% or more of the solvent in the coating liquid and dry the remaining coating liquid by a ventilation drying means. . How much of the solvent in the coating liquid is condensed and recovered depends on the influence on the unevenness of drying of the coating film, production efficiency,
It may be determined by comprehensively judging the above.

In order to accelerate evaporation and condensation of the solvent in the coating liquid, the strip-shaped flexible support 12 and / or the coating film is heated, the condenser plate 30 is cooled, or both of them are adopted. It is preferable. For example, cooling means is arranged in the dryer, and heating means is arranged on the opposite side of the dryer 18 with the strip-shaped flexible support 12 sandwiched therebetween.

In any case, it is desirable that the temperature be controlled in order to control the drying speed of the coating film. The condenser plate 30 is required to be temperature-controlled, and if it is desired to cool it, it is necessary to install equipment for cooling. For cooling, a water-cooled heat exchanger system using a refrigerant or the like, an air-cooling 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 strip-shaped flexible support 12 and / or the coating film, a heater can be provided on the side opposite to the coating film for heating. Further, it is also possible to dispose a transport roll (heating roll) capable of raising the temperature and heat it. In addition, heating may be performed using an infrared heater, microwave heating means, hot air sending means (for example, hot air dryer), or an infrared heater or microwave heating means and hot air sending means may be used in combination.

In the dryer 18 having the structure shown in FIG. 3, the conveyance and heating rollers 38, 38, ... Incorporating a cylindrical heater as a heating means are arranged adjacent to each other over substantially the entire heating zone. . In the dryer 18 having the configuration shown in FIG. 4, the conveyance / heating roller 38 and the guide roller 22 each having a columnar heater as a heating means are incorporated.
And are alternately adjacent to each other and are disposed over the heating zone of substantially the entire area.

A construction in which the dryer 18 is provided with a pressure reducing means can also be preferably adopted. For example, in the configuration shown in FIG. 3, a suction port is provided on the upper side of the dryer 18 and suction is performed by using a suction means such as a blower, so that the belt-shaped flexible support body 12 can be used as a carrier having a cylindrical heater built therein. The heating rollers 38, 38 ... Or the guide rollers 22, 22.

Strip-shaped flexible support 12, coating film, condensing plate 3
When determining the temperature of 0
That is, it is necessary to prevent the evaporated solvent from condensing on a place other than the condensing plate 30, for example, on the surface of the transport roll. Therefore, for example, by making the temperature of the portion other than the condensing plate 30 higher than the temperature of the condensing plate 30, this type of dew condensation can be avoided.

The surface of the coating film and the condensing plate 30 of the dryer 18.
The distance (interval) to the surface needs to be adjusted to an appropriate distance in consideration of the desired drying speed of the coating film. The shorter the distance, the faster the drying speed, but the more easily it is affected by the set distance accuracy. On the other hand, when the distance is increased, not only the drying speed is significantly decreased, but also natural convection due to heat occurs, which causes unevenness in drying. Surface of coating film and dryer 18
The distance from the surface of the condenser plate 30 is preferably 0.1 to 200 mm, more preferably 0.5 to 100 mm.

The dryer 18 does not necessarily have to be linear as shown in FIG. 1, but may be an arc-shaped dryer 18 as shown in FIG. 2, for example. Alternatively, a large drum may be provided and a drier may be provided therein.

In the example shown in FIG. 2, the arc-shaped dryer 18 is brought close to the coating means 16 to improve the solvent recovery efficiency.

As the ventilation drying means, a roller-conveying dryer system, which is used in the prior art, in which the non-coating surface side is supported by a roll and air is blown from the air nozzle to dry the coating surface, A type of non-contact air floating dryer method or non-contact drying method that blows air from the air nozzle on both coated surfaces to dry the support, that is, the support does not come into contact with rolls and the like. It is possible to use a drying device such as a winding type drying method for efficiently utilizing space and drying efficiently. The drying devices of either type are common in that dried air is supplied to the surface of the coating film to dry the coating film.

Other than the above, the feeding device 14, guide roller 22, winding device 24, etc. used in the coating / drying line 10 incorporating the drying device to which the coating film drying method and device of the present invention are applied are commonly used. Members are used, and the description thereof will be omitted.

According to the coating film drying apparatus of the present invention described in detail above, it is possible to suppress unevenness occurring in the coating film immediately after coating and to efficiently and uniformly dry the coating film. Further, since the layout of the coating and drying process is not significantly changed, and further, the physical properties of the coating liquid and the type of solvent are not restricted,
A flexible design of the coating liquid prescription means is possible.

That is, for example, by adding a dryer for condensing and recovering the solvent between the coating section of the coating / drying apparatus including the existing ventilation drying apparatus and the ventilation drying apparatus, the same form as the apparatus of the present invention can be obtained. As a result, the device can be modified at low cost.

The coating film drying apparatus of the present invention is also effective in energy saving and cost reduction. That is, of the vaporized gas generated in the coating / drying line
Solvents other than water cannot be released to the atmosphere as they are, so it is necessary to liquefy and recover the evaporated gas, and a solvent gas recovery facility for that purpose is necessary. However, in the coating / drying line 10, since the solvent can be directly recovered in a liquid state by a dryer that condenses / recovers a part of the coating liquid, the load on the solvent gas recovery equipment can be reduced.

Further, when the coating film drying apparatus of the present invention is used, very uniform drying is possible at the initial stage of drying.
It was found that the following unexpected effects could be obtained. That is, in the conventional ventilation drying device, since the influence of disturbing the coating film cannot be completely suppressed, flow has occurred in the coating film, but by using the device of the present invention, those flows can be prevented, and It was found that the polymer structure in the coating film formed during drying and the network structure of particles can be formed very finely and uniformly.

As a result, not only is the coating film uniformly dried, but the structure of the coating film becomes finer, which leads to the addition of a new additional function in the case of an optical film, for example.

It can be said that the coating film drying apparatus of the present invention is also very suitable for, for example, drying a functional film containing nanoparticles and the like.

The coating film drying apparatus of the present invention can obtain the same effect even when applied to a coating solution in which solid contents such as polymers and particles are dissolved or dispersed. Rather, in a system containing particles and 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 for this system.

[0069]

Example 1 In the step of drying the coating layer in the production line of the optical compensation sheet shown in FIG. 5, the preheating means 32 for heating the flexible belt-shaped support 12 and the solvent in the coating solution are used. The dryer 18 for condensing and collecting the
The structure of a dryer suitable for producing an optical compensation sheet and the conditions for solvent condensation and recovery were examined.

As shown in FIG. 5, the production line of the optical compensation sheet is performed, for example, by the following steps. 1) Delivery step 14 of the transparent film 12; 2) Step 5 of forming a resin layer for forming an alignment film, in which a coating liquid containing a resin for forming an alignment film is applied to the surface of the transparent film and dried.
2; 3) A rubbing step 54 of rubbing the surface of the resin layer on a transparent film having a resin layer for forming an alignment film formed thereon to form an alignment film on the transparent film; 4) a liquid crystalline discotic compound A coating process of applying a liquid crystalline discotic compound on the alignment film with a coating liquid containing 5; 5) a drying process of drying the coating film to evaporate the solvent in the coating film 18; 6) applying the coating film. Liquid crystal layer forming step 58 of heating to a discotic nematic phase forming temperature to form a liquid crystal layer of a discotic nematic phase; 7) solidifying the liquid crystal layer (that is, quenching after forming the liquid crystal layer to solidify, or When a liquid crystalline discotic compound having a crosslinkable functional group is used, the liquid crystal layer is crosslinked by light irradiation (or heating)) Step 60; 8) The alignment film and the liquid crystal layer Winding step 24 for winding the formed transparent film.

In FIG. 5, 50 is a drying zone, 64 is an inspection device, 66 is a protective film, 68 is a laminating machine, and 70 is a dust removing equipment.

The method for producing the optical compensation sheet was continuously carried out continuously from the step of sending out the long transparent film as shown in FIG. 5 to the step of winding the obtained optical compensation sheet. Triacetyl cellulose (Fujitac,
Fuji Photo Film Co., Ltd., thickness: 100 μm, width: 5
00 mm) long film on one side, long-chain alkyl modified Poval (MP-203, Kuraray Co., Ltd.) 5
A weight% solution was applied, dried at 90 ° C. for 4 minutes, and then rubbed to form a resin layer for forming an alignment film having a thickness of 2.0 μm. The transport speed of the film was 20 m / min.

The above triacetyl cellulose film is
Nx, ny, and
Assuming that the refractive index in the thickness direction is nz and the thickness of the film is d, (nx−ny) × d = 16 nm, {(nx−
ny) / 2-nz} xd = 75 nm. The resin layer for forming the alignment film was formed using a coating / drying device.

Then, the film having the obtained resin layer was rubbed on the surface of the resin layer while being continuously conveyed at 20 m / min. The rubbing treatment was performed by rotating the rubbing roller at 300 rpm, and then the obtained alignment film was dust-removed.

Next, while continuously transporting the obtained film having an alignment film at a speed of 20 m / min, the discotic compound TE-8 (3) and TE were deposited on the alignment film.
A photopolymerization initiator (Irgacure 907, manufactured by Ciba-Geigy Co., Ltd.) was added to a mixture of 4: 1 in a weight ratio of (8) (5).
1% by weight of the above mixture was added to a mixture of 10% by weight methyl ethyl ketone solution (coating solution) with a wire bar coating machine 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. 3 seconds after coating, the drying zone was entered, and 3 seconds later, the heating zone was entered. The heating zone was passed in about 3 minutes.

Subsequently, the film coated with the alignment film and the liquid crystal layer was continuously conveyed at 20 m / min, and the surface of the liquid crystal layer was irradiated with ultraviolet rays from an ultraviolet lamp. That is, the film that passed through the heating zone was irradiated with ultraviolet light 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 conducted under the above-mentioned steps under four kinds of conditions. The conditions and results are described below. The following conditions were constant in each of the following tests. That is, the heater temperature was 85 ° C and the condenser plate temperature was 25 ° C. The dryer 18 was arranged such that the inlet was located 500 mm from the coating means 16. The distance between the surface of the coating film and the surface of the condenser plate 30 of the dryer 18 was 0.7 mm.

(Test 1) The preheating means 32 and the dryer 18 have the constructions shown in FIG.

As a result, the strip-shaped flexible support 12 could be heated uniformly, and no problem occurred in the quality of the coating film.

(Test 2) The preheating means 32 shown in FIG. 1 was used, and the dryer 18 shown in FIG. 3 was used. Further, in the configuration shown in FIG. 3, a suction port is provided on the upper side of the dryer 18 and suction is performed by using a suction means (see FIG. 8), whereby the strip-shaped flexible support 12 is obtained.
A conveyance and heating roller 38 having a cylindrical heater built-in,
It was made to adhere to 38 ...

As a result, the strip-shaped flexible support 12 could be heated uniformly, and no problem occurred in the quality of the coating film.

(Test 3) The preheating means 32 and the dryer 18 have the construction shown in FIG. Further, the coating means 16 was provided with a temperature control means to control the temperature of the coating liquid.

As a result, the strip-shaped flexible support 12 could be heated uniformly, and no problem occurred in the quality of the coating film.

(Test 4) The dryer 18 has the structure shown in FIG. The preheating means 32 was not adopted.

As a result, the strip-shaped flexible support 12 could be uniformly heated and dried in the dryer 18, and there was no problem in the quality of the coating film.

(Test 5: Comparative Example) The structure of the dryer 18 is that shown in FIG. The preheating means 32 was not adopted.

As a result, drying unevenness, which is considered to be caused by the non-uniform temperature distribution of the strip-shaped flexible support 12, was generated, which caused a problem in quality.

[Example 2] (Test 1) In the drying step after the undercoat coating in the production line of the cellulose acetate film for sensitization, the case where the dryer for condensing and recovering the solvent in the coating solution of the present invention is provided, A comparison was made with the case where a conventional ventilation drying type dryer is provided.

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 surface of the casting drum, and the film thus formed is peeled off by the peeling roller. It is taken and dried by hot air while traveling between the rolls in the pre-drying process.

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

The condenser plate 30 of the dryer 18 is divided into two zones. Further, both of the two condensing plates 30 were arranged with 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 condenser plate 30 of the dryer 18 is 0.8 mm on the inlet side of the condenser plate 30 on the upstream side and 2 mm on the outlet side toward the downstream side in the traveling direction. The plate 30 was 0.8 mm on the inlet side and 2 mm on the outlet side.

The length of the upstream condenser plate 30 is 2 m,
The length of the condenser plate 30 on the downstream side was 4 m. The set temperature of the condenser plate 30 was set to 15 ° C. in each case.

In the dryer 18, conveyance and heating rollers 38, 3 having a cylindrical heater as a heating means incorporated therein.
8 ... were arranged adjacently over the heating zone of substantially the entire area. Further, a suction port is provided on the lower side of the dryer 18, and suction is performed by using a suction means (vacuum pump), so that the belt-shaped flexible support 12 has conveyance and heating rollers 38, 38 ... Incorporating a cylindrical heater. Was in close contact with.

As a result, there was no problem in the quality of the coating film.

(Test 2: Comparative Example) In the conventional production line shown in FIG. 7, the condenser plate 30 of the dryer 18 is used.
Is not divided into zones, and the condenser plate 30 and the strip-shaped flexible support 12 are arranged substantially parallel to each other. A plate-shaped heater 39 is arranged below the strip-shaped flexible support 12. The other parts of the manufacturing line are the same as the configuration shown in FIG. 6, and the description thereof will be omitted.

As a result, the coating film was unevenly dried.

[0097]

EFFECTS OF THE INVENTION According to the method and apparatus for drying a coating film of the present invention, a long and wide coating film surface formed by coating various liquid compositions on a continuously running strip-shaped flexible support is applied. It is possible to suppress unevenness in drying that occurs immediately after and to efficiently and uniformly dry the coating film.

Further, since the layout of the coating and drying steps is not significantly changed and the physical properties of the coating liquid and the type of the solvent are not restricted, it is possible to flexibly design the coating liquid prescribing means. It is also effective in saving energy and reducing costs.

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

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing an example of a coating / drying line incorporating a drying device to which a coating film drying method and device of the present invention are applied.

FIG. 2 is a conceptual diagram showing another example of a coating / drying line incorporating a drying device to which the coating film drying method and device of the present invention are applied.

FIG. 3 is a conceptual diagram showing still another example of a coating / drying line incorporating a drying device to which the coating film drying method and device of the present invention are applied.

FIG. 4 is a conceptual diagram showing still another example of a coating / drying line incorporating a drying device to which the coating film drying method and device of the present invention are applied.

FIG. 5 is a conceptual diagram showing an example in which the coating film drying apparatus of the present invention is applied to an optical compensation sheet production line.

FIG. 6 is a conceptual diagram showing an example in which the apparatus for drying a coating film of the present invention is applied to a production line for a photosensitive cellulose acetate film.

FIG. 7 is a conceptual diagram showing an example in which a conventional technique is applied to a production line of a cellulose acetate film for photosensitization.

FIG. 8 is a partial enlarged view showing a dryer when the coating film drying apparatus of the present invention is applied to an optical compensation sheet manufacturing line.

[Explanation of symbols]

10 ... Coating / drying line, 12 ... Strip-shaped flexible support, 1
4 ... Delivery device, 16 ... Coating means, 18 ... Dryer,
22 ... Guide roller, 24 ... Winding device, 30 ... Condensing plate, 32 ... Preheating means, 38 ... Conveying and heating roller

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F26B 5/04 F26B 5/04 13/08 13/08 A G11B 5/842 G11B 5/842 B F term ( Reference) 3L113 AA02 AB02 AB06 AC10 AC23 BA26 BA28 DA02 DA24 4D075 BB23X BB24Z BB33X BB33Z BB37Z BB56Z BB92Z BB99Z DA04 DB33 DC21 DC24 DC27 EA05 EC51 4F042 AA22 DA09 DB04 DB17 DB18 DB26 GA02 GA08A22

Claims (23)

[Claims] 1. A method of drying a coating film, which comprises applying a coating solution to a running belt-shaped flexible support by a coating means and drying the applied coating film, wherein the belt-shaped flexible support is provided at a running position before coating. A method for drying a coated film, characterized in that a preheating means for heating the body is provided, and a dryer for condensing and collecting the solvent in the coating liquid is provided on the coating surface side of the running position immediately after coating. 2. A method for drying a coating film, which comprises applying a coating liquid to a running belt-shaped flexible support by a coating means and drying the applied coating film, wherein the coating liquid is applied to the coating surface side at a running position immediately after coating. A method for drying a coated film, characterized in that a dryer for condensing and recovering the solvent therein is arranged, and a heating means is arranged on the opposite side of the dryer across the strip-shaped flexible support. 3. The method for drying a coating film according to claim 1, wherein the coating liquid contains an organic solvent in an amount of 3% by mass or more. 4. The method for drying a coated film according to claim 1, 2 or 3, wherein the coating means is provided with a temperature control means for controlling the temperature of the coating liquid. 5. The distance between the coating means and the dryer is 5
The method for drying a coated film according to claim 1, wherein the coating film has a thickness of m or less. 6. The method for drying a coating film according to claim 1, wherein the distance between the coating means and the dryer is 0.7 m or less. 7. The 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. The method for drying a coated film as described in. 8. 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. The method for drying a coated film as described in. 9. The thickness of the coating film is 0.001 to 0.08.
The method for drying a coating film according to claim 1, wherein the coating film has a thickness of mm. 10. The traveling speed of the strip-shaped flexible support is from 1 to
It is 100 m / min, The drying method of the coating film in any one of Claims 1-9. 11. The traveling speed of the strip-shaped flexible support is 5 to 5.
It is 80 m / min, The drying method of the coating film in any one of Claims 1-10. 12. The dryer comprises 10% of the solvent in the coating liquid.
The method for drying a coated film according to claim 1, wherein the above is condensed and collected. 13. The method for drying a coated film according to claim 1, wherein the dryer is provided with a cooling means. 14. A heating means is arranged on the opposite side of the dryer with the strip-shaped flexible support being sandwiched therebetween.
The method for drying a coated film according to any one of 1. 15. The method for drying a coating film according to claim 14, wherein a heating roll is used as the heating means. 16. The method for drying a coating film according to claim 15, wherein the heating roll is brought into contact with the strip-shaped flexible support. 17. The method for drying a coating film according to claim 14, wherein an infrared heater is used as the heating means. 18. The method for drying a coated film according to claim 14, wherein a hot air sending means is used as the heating means. 19. The method of drying a coating film according to claim 14, wherein an infrared heater and a hot air sending means are used as the heating means. 20. The method for drying a coating film according to claim 1, wherein the dryer is provided with a pressure reducing means. 21. The 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 coated film according to any one of 1. 22. The distance between the surface of the coating film and the surface of the dryer is 0.01 to 100 mm.
The method for drying a coated film according to any one of 1. 23. A coating film drying apparatus for coating a coating liquid on a traveling belt-shaped flexible support and drying the applied coating film, wherein the belt-shaped flexible support is heated to a traveling position before coating. And a dryer for condensing and recovering the solvent in the coating liquid on the coating surface side of the running position immediately after coating. .