JP2003170101A - Method and apparatus for drying coating film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress drying unevenness and to efficiently dry a coating film formed by applying various kinds of liquid compositions on a continuously traveling flexible belt. <P>SOLUTION: A dryer 18 for condensing and recovering a solvent in a coating liquid directly after the various kinds of liquid compositions are applied on the continuously traveling flexible belt 12 by a coating means 16 is arranged in an apparatus for drying the coating film. A condensation plate 20 is arranged in parallel to the flexible belt 12 with a certain interval in the dryer 18. <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 an apparatus for drying a coating film, and more particularly to a long and wide coating film surface formed by coating various liquid compositions on a continuously running strip-shaped flexible support. The present invention relates to a drying method device that dries.

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 device 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, EDCohe.
n'Coating and Drying Defects' (Wiley-Intersci
ece, John Wiley & Sons, Inc.) supports the non-coated side with a roll and blows air from the air nozzle onto the coated 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, as a method of efficiently utilizing space and efficiently drying,
There is a drying method using a string-type drying device as disclosed in 8-42903.

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 uneven due to convection, so-called Yuzu skin (see Yuji Harasaki, "Coating Engineering", P293-294, Asakura Shoten, 1971), etc. 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. Japanese Patent Application Laid-Open No. 9-73016 discloses a method of installing a wire mesh instead of dividing a drying dryer for the same purpose.

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 thickening agent to the coating liquid. And a method of preventing unevenness due to the leveling effect even if the flow of the coating film surface immediately after coating due to the dry air occurs by using a high boiling point solution. .

However, Japanese Patent Laid-Open No. 2001-17054
7. Although the method of Japanese Patent Laid-Open No. 9-73016 is effective in suppressing the inflow of uneven air from the outside of the dryer, it is necessary to greatly reduce the air speed in order to control the air speed so as not to disturb the coating film surface. There is. 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 the high boiling point solution may lead to loss of suitability for high speed coating and increase of 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, US5
186839, US Pat. No. 5,694,701 and the like.

That is, GB1401041 discloses a method of evaporating and collecting 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, US Pat. No. 5,168,639 discloses a method of recovering a solvent by using a drum on an upper portion of a support which runs horizontally. Further, US Pat. No. 5,694,701 proposes a method for improving the layout of US Pat. No. 5,168,639.

[0014]

However, GB1401
In 041, since the inlet and outlet of the support are limited to the upper part of the casing, there are large restrictions in the layout of the apparatus, and it is difficult to incorporate them into the existing coating process. Also, in the example shown in Fig. 5, it is necessary to have a certain distance or more before entering the recovery dryer after coating, and it is necessary to invert the base before entering the recovery dryer, so unevenness immediately after coating is effectively eliminated. It is difficult to keep it well.

In US Pat. No. 5,168,639, since the distance from the coating surface to the condensation / solvent recovery drum varies depending on the coating direction, it is difficult to uniformly control the drying speed over the entire area of the casing, and the casing inlet,
Since the distance between the coating surface and the condensation / cooling drum is unnecessarily large near the outlet, another coating unevenness occurs due to the occurrence of natural convection.

US Pat. No. 5,694,701 (Table 1
511549) discloses a layout improvement method in which the condensation surface is arranged above the coating surface. Among them, it is described that the quality of the lower surface on which the coating liquid is applied is poor, and that it is difficult to efficiently suppress the unevenness of the coating immediately after the coating in the configuration in which the strip-shaped flexible support is inverted after the coating. However, in reality, 1) the film thickness is small, and 2) the case where the organic solvent is contained, it cannot be said that it is unconditionally bad.

Further, when the condensation surface is arranged on the upper side, it is necessary to use a force other than gravity, for example, a force such as a capillary force, so that the condensed liquid does not drop on the application surface. Has been. However, this method requires special measures for liquid recovery, and has a problem that the equipment becomes complicated and expensive.

Similarly, although the above-mentioned three conventional techniques have described in detail the method of recovering the solvent, they do not show a specific method for suppressing the occurrence of coating unevenness immediately after coating.

Similarly, in the method of condensing and recovering the solvent and drying the coating film as in the above-mentioned three types of prior art, the drying efficiency is markedly reduced as compared with ventilation drying. Moreover, the above-mentioned prior art does not describe an improved method or the like for efficiently drying the coating film in the entire drying system.

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.

[0021]

In order to achieve the above-mentioned object, the present invention applies a coating liquid to a running belt-shaped flexible support by a coating means, and a solvent in the coating liquid is applied to a running position immediately after coating. In the method for drying a coating film, in which a dryer for condensing and recovering the strip-shaped flexible support is provided, the dryer has a plate-like shape below the strip-shaped flexible support and substantially parallel to the strip-shaped flexible support at a predetermined distance. It is characterized in that a condenser plate which is a member is arranged.

Further, according to the present invention, a coating film is provided in which a coating solution is applied to a running belt-shaped flexible support by a coating means, and a drier for condensing and collecting the solvent in the coating solution is provided at a running position immediately after the coating. In the drying method, the dryer is provided with a condenser plate, which is a plate-shaped member, above the strip-shaped flexible support and substantially parallel to the strip-shaped flexible support at a predetermined distance. It is characterized in that the condenser plate is inclined upward by 5 degrees or more toward the running direction 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 strip-shaped flexible support, the coating liquid is immediately after the coating means. A dryer for condensing and recovering the solvent of No. 3 is provided, and it is possible to suppress unevenness in drying that tends to occur immediately after coating and to dry efficiently.

Particularly, the effect is great when the coating solution contains an organic solvent or when the solvent of the coating solution is entirely composed of the organic solvent.

In the present invention, it is preferable that the coating means is disposed below the strip-shaped flexible support. With such a structure, the state of the applied coating film is stabilized.

Further, in the present invention, the coating liquid preferably 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, and 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.

[0028]

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.

FIGS. 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
Is a feeding device (not shown) that mainly feeds the strip-shaped flexible support 12 wound in a roll shape, an application unit 16 that applies a coating liquid to the strip-shaped flexible support 12, and a strip-shaped flexible support. A dryer 18 for condensing and collecting the solvent in the coating liquid of the coating film formed by coating on 12, and a winding device (not shown) for winding the product manufactured by coating and drying,
It is formed by a number of guide rollers 22, 22 ... Which form a transport path along which the strip-shaped flexible support 12 travels. Also,
A ventilation drying means for drying the coating film is provided downstream of the dryer 18 as required.

FIG. 3 is a conceptual diagram showing another example of a coating / drying line 10 incorporating a drying device to which the coating film drying method and device of the present invention are applied. The coating / drying line 10 in this example mainly has the same configuration as in FIGS. 1 and 2.
A feeding device (not shown) for feeding the strip-shaped flexible support 12 wound in a roll shape, an application unit 16 for applying a coating liquid to the strip-shaped flexible support 12, and a coating formation on the strip-shaped flexible support 12. The dryer 18 for condensing and collecting the solvent in the coating liquid of the coating film thus formed, and the winding device (not shown) for winding the product manufactured by coating and drying, and the transport in which the strip-shaped flexible support 12 runs. It is formed by a number of guide rollers 22, 22 ... Which form a path.

However, unlike the structure shown in FIGS. 1 and 2, the coating film applied and formed on the strip-shaped flexible support 12 is on the upper side, and the dryer 18 is arranged above the strip-shaped flexible support 12 and The condensing plate 20 described later is a strip-shaped flexible support 12
Is inclined upward at a predetermined angle α of 5 degrees or more in the traveling direction of.

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

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 such that the coating surface is on the lower side in the horizontal direction as shown in FIGS. 1 and 2, or it is on the upper side in the horizontal direction. Such a configuration may be adopted. Further, as shown in FIG. 3, the structure may be inclined with respect to the horizontal direction.

As shown in FIG. 4, 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 plate-like member provided in parallel with the belt-shaped flexible support 12 at a predetermined distance, and a condenser plate 20, and is provided upright from the front and rear sides of the condenser plate 20 (FIG. 3). It is hung vertically downward) and is composed of a side plate and the like. As a result, when the solvent in the coating liquid for the coating film volatilizes, the volatilized solvent is condensed and collected on the condenser plate 20.

The material used for the surface of the condensing plate 20 for condensing the solvent is not particularly limited, and may be metal, plastic, wood or the like, 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 recovering the solvent condensed on the condensing plate 20 is, for example, provided with a groove on the condensing surface of the condensing plate 20 and recovering 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 20 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 20a for collecting the condensed solvent is provided below the right end of the condensing plate 20, and the solvent is collected through the gutter 20a. If the gutter 20a is provided in this way, the condensed solvent can be easily recovered. The position at which the gutter 20a is provided is not limited to the example shown in the figure, and depending on the configuration of the condensing plate 20, the condensing plate 20
It is provided at an appropriate position such as a downstream side or a side surface of the. In any case, it is preferably provided at a position where the solvent can be collected by flowing down.

Such a gutter 20a is also provided in the example shown in FIG. Thus, the gutter 20
When the condensed solvent is recovered using a, it is preferable that the condenser plate 20 is arranged with an inclination of 5 degrees or more with respect to the horizontal plane.

The dryer 18 has a plate-shaped condensing plate 20.
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. Moreover, you may use together with the collection | recovery apparatus as shown by US5694701.

The dryer 18 is preferably arranged as close as possible to the coating means 16 in order to prevent uneven drying of the coating film due to 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. The strip-shaped flexible support 12 is the coating means 16.
It is more preferable that the speed is such that the dryer 18 is reached within 20 seconds after the application.

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 more 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 the 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 20 is cooled, or both means 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 20 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, or the like.

Band-shaped flexible support 12, coating film, condensing plate 2
When determining the temperature of 0
That is, it is necessary to prevent the evaporated solvent from being condensed on a place other than the condensing plate 20, for example, on the surface of the transport roll. Therefore, for example, by making the temperature of the portion other than the condensing plate 20 higher than the temperature of the condensing plate 20, dew condensation of this kind can be avoided.

The surface of the coating film and the condensing plate 20 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 20 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 FIGS. 1 to 3, and may be, for example, an arc dryer. Alternatively, a large drum may be provided and a drier may be provided therein.

As a ventilation drying means used as needed, a roller conveyer which is used in the prior art, in which a non-coated surface side is supported by a roll and air is blown from an air nozzle to the coated surface side for drying. Dryer method, non-contact type air floating dryer method, non-contact type, in which air is blown from the air nozzles on both the coated and non-coated surfaces to dry the support while it is floating It is a kind of the drying method of the type, and a drying device such as a string-type drying method for efficiently using the space and drying efficiently can be used. 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.

In addition, a feeding device and a guide roller 2 used in a coating / drying line 10 incorporating a drying device to which the coating film drying method and device of the present invention are applied.
2. Conventional members are used for the winding device and the like, 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 collecting 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 saving energy and reducing costs. 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.

When the apparatus for drying a coated film of the present invention is used, very uniform drying can be carried out 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 same effect can be obtained when the coating film drying apparatus of the present invention is applied to a coating solution in which solid components 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.

[0063]

EXAMPLES Example 1 A dryer 18 for condensing and recovering a solvent in a coating solution is provided in a step of drying a coating layer in the optical compensatory sheet production line shown in FIG. The structure of a suitable dryer and the conditions for condensing and recovering the solvent in the production were examined.

As shown in FIG. 4, 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, rapidly cooling 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. 4, 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 of producing the optical compensation sheet was continuously and continuously carried out from the step of sending out the long transparent film as shown in FIG. 4 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-mentioned 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.

Subsequently, the film having the resin layer thus obtained 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.

On the other hand, as a comparative example, as shown in FIG. 5, the strip-shaped flexible support 12 is applied by the coating means 16.
The coating liquid is applied to the lower surface of the substrate, and then the strip-shaped flexible support 1
2 was reversed by the guide rollers 22, 22, 22 so that the coating surface of the coating liquid would face the upper surface and the dryer 18 was inserted. Other configurations were the same as those in the example.

Through the above steps, the following examples (Example 1,
The test was conducted under the conditions of Example 2) and Comparative Example. The conditions and results are described below.

(Example 1) The structure around the dryer 16 is arranged as shown in FIG. In the dryer 18, a condensing plate 20 which is a plate-like member is arranged below the strip-shaped flexible support 12 and substantially parallel to the strip-shaped flexible support 12 at a predetermined distance.

Heater temperature is 85 ° C., condensing plate temperature is 25 ° C.
And The dryer 18 has an inlet from the coating means 16 to 50.
It was arranged so that the position was 0 mm. The distance between the surface of the coating film and the surface of the condenser plate 20 of the dryer 18 was 1 mm.

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

(Example 2) The structure around the dryer 16 is arranged as shown in FIG. In the dryer 18, a condensing plate 20 which is a plate-shaped member is arranged above the strip-shaped flexible support 12 and substantially parallel to the strip-shaped flexible support 12 at a predetermined distance.
The inclination angle α was 15 degrees.

Heater temperature is 85 ° C., condensing plate temperature is 25 ° C.
And The dryer 18 has an inlet from the coating means 16 to 50.
It was arranged so that the position was 0 mm. The distance between the surface of the coating film and the surface of the condenser plate 20 of the dryer 18 was 1 mm.

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

(Comparative Example) The structure around the dryer 18 is shown in FIG.
The arrangement is as shown in. In the dryer 18, a condensing plate 20 which is a plate-like member is arranged below the strip-shaped flexible support 12 and substantially parallel to the strip-shaped flexible support 12 at a predetermined distance.

Heater temperature is 85 ° C., condensing plate temperature is 25 ° C.
And The drier 18 has an inlet having coating means 16 to 10
It was arranged so as to be at the position of m. That is, the dryer 18
The arrangement position of the coating means 1 is not the traveling position immediately after coating, but the coating means 1
It was set at a position apart from 6 by a predetermined distance. The distance between the surface of the coating film and the surface of the condenser plate 20 of the dryer 18 was 1 mm.

As a result, the coating film suffered from uneven drying and defective alignment.

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

In the production line using the dryer according to 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 20 of the dryer 18 was divided into two zones. Further, both of the two condenser plates 20 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 20 of the dryer 18 is 0.8 mm on the inlet side of the condenser plate 20 on the upstream side and 2 mm on the outlet side toward the downstream side in the traveling direction. The plate 20 has an inlet side of 0.8 mm and an outlet side of 2 mm.

The length of the condenser plate 20 on the upstream side is 2 m,
The length of the condenser plate 20 on the downstream side was 4 m. The set temperature of the condenser plate 20 was set to 15 ° C. in each case.

The surface properties of the manufactured product were good.

In the manufacturing line shown in FIG. 7 using a conventional ventilation drying type dryer, the apparatus for the undercoat coating drying step is a normal ventilation drying type dryer.
The other parts of the manufacturing line are the same as those shown in FIG. 6, and the description thereof will be omitted.

The surface quality of the manufactured product was defective due to uneven drying in the undercoat.

[0090]

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 largely changed and the physical properties of the coating liquid and the type of solvent are not restricted, the coating liquid prescribing means can be flexibly designed. 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 an example in which the coating film drying apparatus of the present invention is applied to an optical compensation sheet production line.

FIG. 5 is a conceptual diagram showing an example in which a coating film drying device of a comparative example is applied to an optical compensation sheet manufacturing 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 dryer of a ventilation drying type is applied to a production line of a cellulose acetate film for photosensitization.

FIG. 8 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.

[Explanation of symbols]

10 ... Coating / drying line, 12 ... Strip-shaped flexible support, 1
4 ... Delivery device, 16 ... Coating means, 18 ... Dryer,
20 ... Condensing plate, 22 ... Guide roller, 24 ... Winding device

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G11B 5/842 G11B 5/842 BF term (reference) 3L113 AA02 AB02 AB06 AB07 AC10 AC12 BA26 BA28 DA02 DA24 4D075 BB18Z BB24Z BB37Z BB92Z BB99Z DA04 DB33 DC21 DC24 DC27 EA05 EC51 4F042 AA22 DB04 DB17 DB18 5D112 AA05 AA22 GA02 GA08 GA19

Claims (21)

[Claims] 1. A method for drying a coating film, which comprises applying a coating solution to a running belt-shaped flexible support by a coating means, and providing a dryer for condensing and collecting the solvent in the coating solution at a running position immediately after the coating. The coating film is characterized in that, in the dryer, a condensing plate, which is a plate-shaped member, is arranged below the strip-shaped flexible support and substantially parallel to the strip-shaped flexible support at a predetermined distance. How to dry. 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 providing a dryer for condensing and collecting the solvent in the coating liquid at a running position immediately after the coating. In the dryer, a condensing plate, which is a plate-shaped member, is arranged above the strip-shaped flexible support and substantially parallel to the strip-shaped flexible support at a predetermined distance, and the condensing plate is strip-shaped. A method for drying a coated film, which comprises tilting the flexible support upward by 5 degrees or more in the running direction. 3. The method for drying a coating film according to claim 1, wherein the coating means is disposed below the strip-shaped flexible support. 4. The method for drying a coating film according to claim 1, 2 or 3, wherein the coating liquid contains 3% by mass or more of an organic solvent. 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 coated 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 method for drying a coated film according to claim 1, wherein the dryer is provided with a cooling means. 13. The method of drying a coating film according to claim 1, wherein a heating means is arranged on the opposite side of the dryer with the strip-shaped flexible support being sandwiched therebetween. 14. The method for drying a coating film according to claim 13, wherein a heating roll is used as the heating means. 15. The method for drying a coating film according to claim 13, wherein an infrared heater or a microwave heating means is used as the heating means. 16. 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. 17. 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. 18. The method for drying a coating film according to claim 1, wherein the dryer is provided with a gutter for collecting a solvent. 19. The method for drying a coating film according to claim 1, wherein the dryer is provided with a groove for collecting a solvent. 20. Drying of a coating film having a drier, which is arranged at a subsequent stage of the coating means for coating the running strip-shaped flexible support with the coating liquid and condenses and recovers the solvent in the coated coating solution. In the apparatus, the dryer is provided with a condensing plate, which is a plate-shaped member, below the strip-shaped flexible support and substantially parallel to the strip-shaped flexible support at a predetermined distance. A coating film drying device. 21. Drying of a coating film having a drier, which is disposed in a subsequent stage subsequent to a coating means for coating a running strip-shaped flexible support with a coating liquid and condenses and recovers a solvent in the coated coating solution. In the apparatus, the dryer is provided with a condenser plate, which is a plate-shaped member, above the strip-shaped flexible support and substantially parallel to the strip-shaped flexible support at a predetermined distance. An apparatus for drying a coating film, wherein the condensing plate is arranged upward with an inclination angle of 5 degrees or more toward the running direction of the strip-shaped flexible support.