JP5720139B2 - Curtain coating apparatus and curtain coating method - Google Patents

Description

  The present invention relates to a curtain coating apparatus and a curtain coating method.

Conventionally, a curtain coating method has been proposed as a coating method used for manufacturing a photographic photosensitive material such as a photographic film.
In the curtain coating method, (i) a support body (web, base material) that continuously travels by discharging the coating liquid from a nozzle slit and freely dropping the discharged coating liquid by a curtain edge guide that guides the curtain. (Ii) A curtain edge guide that discharges the coating liquid from the slit, moves the discharged coating liquid on the slide surface, and guides the coating liquid in a curtain shape. A method of forming a coating film while allowing it to freely fall and collide on a continuously running web; (iii) a curtain edge that discharges coating liquids of different compositions from each nozzle slit and guides the discharged coating liquid in a curtain shape A method of forming a coating film while allowing it to fall freely with a guide and colliding with each web on a web that runs sequentially from each nozzle slit (multilayer coating method) (Iv) discharging a coating liquid having a different composition from each nozzle slit, laminating the discharged coating liquid on a slide surface, and dropping the laminated coating liquid freely with a curtain edge guide that guides in a curtain shape; There is a method (multilayer coating method) in which a coating film is formed while colliding with a web that runs continuously.
However, in the curtain coating method, when the coating solution freely falls, a portion (boundary layer) where the coating solution flows slowly in the vicinity of both ends of the curtain film is generated. When the coating film is formed while colliding on the continuously running web, the thin film portion 20a (FIG. 1) is formed near the end in the width direction of the coating film 20 (FIG. 1). There is a problem that the thick film portion 20b (FIG. 1) is formed inside the coating film 20 (FIG. 1) in the width direction.

In order to prevent the boundary layer from being formed on the curtain film, the boundary layer is formed on the curtain film by defining the viscosity and surface tension of the coating liquid and the shape of the liquid contact surface of the edge guide. In order to prevent the formation of the thin film portion 20a and the thick film portion 20b due to the contraction of the coating liquid, and to make the coating thickness uniform (see, for example, Patent Document 1). .
However, this technique has a problem that the influence of the boundary layer can be reduced only under limited physical properties of the coating solution, and it is extremely difficult to regulate the viscosity and surface tension of the coating solution. is there.

Further, in order to prevent the boundary layer from being formed on the curtain film, the edge guide auxiliary liquid is discharged to the edge guide in the flow direction of the coating liquid, thereby suppressing the formation of the boundary layer in the vicinity of both ends of the curtain film. A technique has been proposed (see, for example, Patent Document 2).
However, this technique has a problem that the curtain film is not sufficiently accelerated by the edge guide auxiliary liquid and the boundary layer cannot be completely eliminated.

In order to stabilize the free fall of the coating liquid, the flow surface of the edge guide auxiliary liquid is formed into an arc-shaped convex shape, and when there is no disturbance due to wind, the curtain film is positioned at the tip of the convex portion, When the curtain film deviates from the tip of the convex part due to disturbance, a technique has been proposed that expresses the alignment of the curtain film by returning the displaced curtain film to the tip of the convex part by increasing the dynamic surface tension of the coating liquid. (For example, see Patent Document 3).
However, in this technique, when the static surface tension of the coating solution is as small as about 35 mN / m or less, the curtain film is displaced from the tip of the convex portion due to the disturbance due to the wind, and sticks to the side surface of the edge guide. There is a problem of non-uniformity, and there is a problem that uniformity of the coating film is lost due to non-linear dropping, and uneven coating occurs, and the edge guide auxiliary liquid is discharged by the coating liquid. There is a problem that the porous material for clogging causes clogging and the discharge of the edge guide auxiliary liquid becomes non-uniform.
When the coating liquid adheres to the porous material, it is washed with a solvent such as hydrochloric acid, but the disassembling operation is not easy, it is difficult to remove clogging, and the edge guide does not clog. The development of was strongly sought.
In order to solve the above-mentioned clogging problem, a technique has been proposed in which the auxiliary water flow lower surface of the edge guide is used as a metal surface, and auxiliary water is discharged from a discharge port provided on the metal surface (see, for example, Patent Document 4). ).
However, since the edge guide auxiliary water directly flows into the discharge port in the above technique, there is a problem that the edge guide auxiliary water is not uniformly discharged, and the auxiliary water flow bottom surface is flat, so the auxiliary water is straight. There is a problem that the curtain film is not stabilized without falling, and a problem that the curtain film does not swing due to disturbance caused by wind.

  An object of the present invention is to solve the above-described problems and achieve the following objects. That is, the present invention prevents curtain film destabilization due to disturbance of auxiliary water and disturbance due to wind, and can control the film thickness of the curtain film due to the influence of the boundary layer in the vicinity of the guide means. An object is to provide an apparatus and a curtain coating method.

Means for solving the problems are as follows. That is,
<1> Curtain in the width direction substantially perpendicular to the flow-down direction of the curtain film by the coating liquid, having a discharge means having a coating liquid discharge port for discharging the coating liquid and an auxiliary water introduction port for introducing auxiliary water A pair of guide means for supporting both ends of the film and guiding the curtain film onto the transported support; and a transport means for transporting the support; and the pair of guide means, Each has a concave portion through which the auxiliary water flows, and a concave side surface formed substantially perpendicular to the bottom surface of the concave portion, and an exposed surface formed continuously and intersecting with the side surface of the concave portion. A curtain coating apparatus characterized by
<2> The curtain coating apparatus according to <1>, wherein the maximum depth of the concave portion is 0.2 mm to 0.5 mm.
<3> The curtain coating apparatus according to any one of <1> to <2>, wherein the maximum distance between the side surfaces of the recesses is 1.5 mm to 4.0 mm.
<4> The above-mentioned <1> to <3>, wherein the guide means has a flat surface above the auxiliary water inlet in the auxiliary water flow direction, and the flat surface is a rectangle having a length of 5 mm to 15 mm and a width of 7 mm or more. A curtain coating apparatus according to any one of the above.
<5> The curtain coating apparatus according to any one of <1> to <4>, wherein the auxiliary water introduction speed is 0.4 m / second to 2.1 m / second.
<6> The curtain coating apparatus according to any one of <1> to <5>, wherein the maximum interval of the auxiliary water introduction port in the flow direction of the auxiliary water is 0.2 mm to 0.5 mm.
<7> By a discharge process for discharging the coating liquid from the coating liquid discharge port and a pair of guide means having an auxiliary water introducing port for introducing auxiliary water, it is substantially perpendicular to the flow-down direction of the curtain film by the coating liquid. Including a guide step for supporting both ends of the curtain film in the width direction and guiding the curtain film onto the transported support, and a transport process for transporting the support, wherein the pair of guide means includes: Each has a concave portion through which the auxiliary water flows, and a concave side surface formed substantially perpendicular to the bottom surface of the concave portion, and an exposed surface formed continuously and intersecting with the concave side surface The curtain coating method is characterized in that:
<8> The curtain coating method according to <7>, wherein the maximum depth of the concave portion is 0.2 mm to 0.5 mm.
<9> The curtain coating method according to any one of <7> to <8>, wherein the maximum distance between the side surfaces of the recesses is 1.5 mm to 4.0 mm.
<10> The above-mentioned <7> to <9>, wherein the guide means has a flat surface above the auxiliary water inlet in the auxiliary water flow direction, and the flat surface is a rectangle having a length of 5 mm to 15 mm and a width of 7 mm or more. The curtain coating method according to any one of the above.
<11> The curtain coating method according to any one of <7> to <10>, wherein the auxiliary water introduction speed is 0.4 m / second to 2.1 m / second.
<12> The curtain coating method according to any one of <7> to <11>, wherein a maximum interval of the auxiliary water introduction port in the flow direction of the auxiliary water is 0.2 mm to 0.5 mm.

According to the present invention, the above problems can be solved and the object can be achieved,
A curtain coating apparatus and a curtain coating method capable of preventing destabilization of a curtain film due to disturbance of auxiliary water and disturbance due to wind, and controlling the film thickness of the curtain film due to the influence of the boundary layer in the vicinity of the guide means Can be provided.

FIG. 1 is a diagram for explaining a thin film portion and a thick film portion of a coating film. FIG. 2 is a schematic view showing an example of the slide curtain coating apparatus of the present invention. FIG. 3 is a schematic view showing an example of the slot curtain coating apparatus of the present invention. FIG. 4 is a schematic view showing another example of the slot curtain coating apparatus of the present invention. FIG. 5 is a view for explaining an example of an edge guide (guide means) in the curtain coating apparatus of the present invention. FIG. 6 is a front view showing an example of an edge guide (guide means) in the curtain coating apparatus of the present invention. FIG. 7 is a view showing an example of an internal structure of an edge guide (guide means) in the curtain coating apparatus of the present invention (second manifold stage). FIG. 8 is a cross-sectional view showing an example of an edge guide (guide means) in a conventional curtain coating apparatus. FIG. 9 is a cross-sectional view showing an example of an edge guide (guide means) in the curtain coating apparatus of the present invention. FIG. 10 is a diagram for explaining die coating (part 1). FIG. 11 is a diagram for explaining die coating (part 2). FIG. 12 is a perspective view showing an example of an edge guide (guide means) in the curtain coating apparatus of the present invention. FIG. 13 is a perspective view showing another example of an edge guide (guide means) in the curtain coating apparatus of the present invention. FIG. 14 is a diagram for explaining a boundary layer between the curtain film and the auxiliary water. FIG. 15 is a graph showing the evaluation results of the flow rate distribution in the width direction of the curtain films of Examples 1 and 13 to 19. FIG. 16 is a graph showing the evaluation results of the flow rate distribution in the width direction of the curtain films of Examples 1 and 21. FIG. 17 is a graph showing the evaluation results of the drop speed at a height position of 10 mm from the lower end of the slide die of Examples 1, 13, 14 and 18. FIG. 18 is a graph showing the evaluation results of the drop speed at a height position of 140 mm from the lower end of the slide die of Examples 1, 13, 14 and 18.

(Curtain coating device and curtain coating method)
The curtain coating apparatus of the present invention is intended for web coating, and includes at least a discharge unit, a pair of guide units, and a transport unit, and further includes other units as necessary.
The curtain coating method of the present invention is intended for web coating, and includes at least a discharge process, a guide process, and a transport process, and further includes other processes appropriately selected as necessary.

<Discharge means, discharge process>
The discharge means is a means having a coating liquid discharge port for discharging a coating liquid, and the discharging step is a step of discharging the coating liquid from a slit.

-Coating liquid-
There is no restriction | limiting in particular as said coating liquid, According to the objective, it can select suitably, For example, an acrylic emulsion, a heat sensitive liquid, a thermal transfer ribbon coating liquid, a water-system coating liquid, a solvent-type coating liquid etc. are mentioned.

As the viscosity of the coating solution, there are a slot die type curtain and a slide die type curtain as a curtain coating device, and an appropriate viscosity range varies depending on one of them. In the curtain coating method, the viscosity of the coating solution needs to be adjusted to an appropriate viscosity range.
The suitable viscosity range is not particularly limited and may be appropriately selected depending on the intended purpose. However, in a slot die type curtain, the low shear viscosity is preferably 1 mPa · s to 2,000 mPa · s, and the slide die type is used. In the curtain, the viscosity is preferably 1 mPa · s to 500 mPa · s, and in the coating liquid having the physical property value of shear thinning, the viscosity is preferably in the above-mentioned viscosity range at a low shear.
In the slot die type curtain, when the viscosity of the coating liquid is low, when the coating is temporarily interrupted by adjustment during operation, when dripping occurs from the slit of the die and exceeds 2,000 mPa · s, 1) Bubbles in the liquid are difficult to escape, causing bubble defects due to bubbles in the liquid, (2) Since the discharge pressure of the coating liquid increases, the load on the liquid feed pump increases, and the pressure resistance of the liquid supply system Is required. In the case of the slide die type curtain, the viscosity should be low considering the film thickness uniformity. When the viscosity is high, the flow rate of the coating liquid is near the slide edge guide (9 in FIG. 2) between the slide parts. Since the boundary layer is generated as described above, a thick film portion is generated between the flow of the slide portion due to the viscous resistance. In the case of exceeding 500 mPa · s, due to the thickening mechanism during the slide flow as described above, the film thickness exceeds 20% in the section of 10 mm to 40 mm from the center flat part, and the film thickness is uneven. Failure occurs, winding failure and drying failure occur.
The viscosity can be measured using a B-type viscometer or the like.

There is no restriction | limiting in particular as surface tension of the said coating liquid, Although it can select suitably according to the objective, 20 mN / m-40 mN / m are preferable.
When the surface tension is less than 20 mN / m, since the surface tension of the film itself is weak, the film tension is weak, and the film is easily deformed and shaken due to wind disturbance. When the surface tension exceeds 40 mN / m, the curtain film is rounded up.
The surface tension can be measured by, for example, a platinum plate method using a FACE automatic surface tension meter (manufactured by Kyowa Interface Science) or the like. Further, as described in Brown's document “A study of the behavior of a thin sheet of moving liquid J. Fluid Mechanicals, 10: 297-305”, a film formed by inserting a needle-like foreign substance into the curtain film. By measuring the split angle, the dynamic surface tension of the curtain film can be measured.
Since the mechanism of the curtain film cut-off is caused by the balance between the dynamic surface tension and the dynamic pressure of the curtain film, it is important to measure and evaluate the dynamic surface tension of the film.

-Coating liquid slit-
The cross-sectional shape of the coating liquid slit is a rectangular cross section.
There is no restriction | limiting in particular as a magnitude | size of the said coating liquid discharge outlet, Although it can select suitably according to the objective, It is preferable that the clearance gap between slits is about 0.2 mm-0.5 mm.
The gap between the slits has a function of making the coating liquid uniform in the width direction, and the size of the gap is “Slot Coating: Fluid machinery and die design, Sartor, Luigi, Ph.D. University of Minnesota, 1990”, etc. As shown in Fig. 4, it varies depending on the size and shape of the die manifold, the distance from the manifold to the slit outlet, the presence / absence and position of the second manifold, and also varies depending on the flow rate and viscosity of the coating liquid.

The material of the coating liquid discharge port is not particularly limited and may be appropriately selected depending on the intended purpose. However, a metal surface such as SUS, aluminum, or hard chrome plating is preferable.
Even in the case where the coating solution contains a resin, a metal is preferable because clogging can be prevented.

-Discharge mechanism-
As a discharge mechanism for discharging the coating liquid, there are a slot die type curtain and a slide die type curtain, which are appropriately selected according to the application.
The slot die type curtain is used when applying one or two layers of coating liquid, and since the slit is downward, when the viscosity of the coating liquid is low, dripping occurs or bubbles in the liquid are transferred to the die head. May stay in the manifold. However, since the discharge speed of the coating liquid is faster than that of the slide die type curtain, the dynamic surface tension is determined by the balance between the dynamic surface tension of the coating liquid and the dynamic pressure (inertial force) when the coating liquid drops. Considering the mechanism of the curtain film breaking up when the film is large, the slot die curtain is difficult to break up. Also, since there is no open space, such as the slide flow bottom surface, it is easy to clean, there are few cleaning liquids such as water used for cleaning, and when the viscosity of the coating liquid is high, even during temporary interruption during operation Easy.
The slide die type curtain is used when applying a multi-layer coating liquid from 1 layer to 3 layers or more, and since the slit is upward, it is difficult for bubbles to accumulate in the die head manifold, but the area of the slide portion is small. It is large and is not easy to clean, and requires a large amount of cleaning liquid when temporarily interrupted during operation compared to a slot die curtain.

-Flow rate of coating solution-
The flow rate at which the coating liquid is discharged is not particularly limited as long as the curtain film can be formed, and can be appropriately selected according to the purpose.
In the slot die type curtain, there is no problem as long as the slit and the manifold shape can discharge a desired flow rate and form a curtain film.
The slide die type curtain has the slit and manifold shape capable of discharging a desired flow rate, and there is no problem if a curtain film can be formed after flowing down the slide surface after being discharged from the slit. When the flow rate is relatively large, the curtain film thickness becomes thick at the upper part of the curtain film. Therefore, the width of the groove of the edge guide (w in FIG. 6) needs to be set appropriately according to the flow rate at the upper part of the edge guide. There is.

<Guiding means, guidance process>
As shown in FIG. 5, the guide means has an auxiliary water introduction port 14 for introducing auxiliary water, and has a width substantially perpendicular to the flow-down direction of the curtain film 6 by the coating liquid (arrow direction in FIG. 5). Is a pair of means 2 that supports both ends of the curtain film in the direction and guides the curtain film 6 onto the transported support body 5, and the guiding step includes an auxiliary water inlet 14 that discharges auxiliary water 1. The pair of guiding means 2 supports both ends of the curtain film in the width direction substantially perpendicular to the flow-down direction of the curtain film 6 by the coating liquid (arrow direction in FIG. 5), and the curtain film 6 is conveyed. It is a step of guiding on the support 5.
As shown in FIGS. 6 and 9, the guide means has an auxiliary water flow groove (recess) 16 through which auxiliary water flows, and is formed substantially perpendicular to the bottom surface 16 a of the auxiliary water flow groove (recess) 16. The auxiliary water flow lower groove side surface (recess side surface) 16b and the exposed surface 21 formed so as to be continuous with and intersect with the auxiliary water flow lower groove side surface (recess side surface) 16b form an acute angle θ.
As shown in FIG. 12, the guide means preferably has a plane 40 having a length of 5 mm to 15 mm and a width of 7 mm or more above the auxiliary water introduction port 14 in the auxiliary water flow downward direction. By having the flat surface 40, it is possible to avoid the curvature of the curtain film (teapot effect) due to the speed difference between the slide surface and the free surface.

-Auxiliary water (edge guide water, auxiliary liquid)-
The auxiliary water needs to be appropriately selected according to the coating solution. In order to exhibit the effect of holding the curtain film to the edge guide by pulling the coating solution by the auxiliary water, that is, so-called alignment, it is necessary to make the auxiliary water always higher than the coating solution. For example, water is used for water, a solvent is used if the coating solution is solvent, and a mixed solution in which water, a solvent, a resin, a surfactant, or the like is mixed.

-Auxiliary water inlet-
There is no restriction | limiting in particular as the maximum space | interval (G in FIG. 6) regarding the flow direction of the auxiliary water of the said auxiliary water introduction port as said auxiliary water introduction port, Although it can select suitably according to the objective, 0. 2 mm to 0.5 mm is preferable, and 0.2 mm to 0.4 mm is more preferable.
If the maximum distance is less than 0.2 mm, cleaning of the inside of the inlet is not easy, and if it exceeds 0.5 mm, the discharge uniformity of the auxiliary water may be impaired.
There is no restriction | limiting in particular as the maximum width (W in FIG. 6) regarding a perpendicular | vertical direction with respect to the flow direction of the auxiliary water of the said auxiliary water inlet, Although it can select suitably according to the objective, 1.5 mm-4 mm Is preferable, and 2 mm to 3 mm is more preferable.
If the maximum width is less than 1.5 mm, there may be a problem in processing accuracy, and if it exceeds 4 mm, the auxiliary water may not flow uniformly over the entire width.
The introduction speed of the auxiliary water is not particularly limited as long as the auxiliary water flows in the flow surface, and can be appropriately selected according to the purpose. However, the introduction speed is 0.4 m / second to 2.1 m / second. Preferably, 0.8 m / second to 1.6 m / second is more preferable.
When the introduction speed of the auxiliary water is less than 0.4 m / sec, a boundary layer may be generated, and when it exceeds 2.1 m / sec, the auxiliary water may be introduced obliquely downward.

The auxiliary water inlet has a slit shape with a rectangular cross section, and the flow path in the edge guide is preferably a long slit shape. However, when clogging occurs, if the slit is long, it is practically difficult to have a long slit inside because it is difficult to clean or structurally.
Therefore, it is preferable to have a manifold as shown in FIG. 7 inside the edge guide, and by having a second-stage manifold as shown in FIG. 7, the distance to the auxiliary water inlet can be shortened. The auxiliary water can be discharged uniformly.

  The material of the auxiliary water inlet is not particularly limited and can be appropriately selected according to the purpose. However, clogging can be prevented even when the coating liquid or auxiliary water contains a resin. In this respect, metal is preferable.

-Auxiliary water flow ditch (concave)-
The auxiliary water flow lower groove (recessed portion) has a bottom surface and a recessed side surface formed substantially perpendicular to the bottom surface.
The concave side surface and the exposed surface formed continuously and intersecting with the concave side surface form an acute angle.

The acute angle is not particularly limited as long as it is less than 90 °, but is preferably 30 ° to 80 °, and more preferably 45 ° to 60 °.
If the acute angle is less than 30 °, accuracy may be affected in processing, and if it exceeds 80 °, the effect of the acute angle may be impaired. On the other hand, when the acute angle is within a more preferable range, it is advantageous in terms of retaining edge guide auxiliary water.

There is no restriction | limiting in particular as the maximum depth (h in FIG. 9) of the said auxiliary water flow ditch | groove (recessed part), Although it can select suitably according to the objective, 0.2 mm-0.5 mm are preferable, 0.2 mm -0.35 mm is more preferable.
If the maximum depth is less than 0.2 mm, the auxiliary water may overflow from the auxiliary water flow lower groove (recess), and if it exceeds 0.5 mm, turbulence may occur.

There is no restriction | limiting in particular as the maximum space | interval (maximum width W of the auxiliary water flow ditch | groove (recessed part in FIG. 9) of the auxiliary water flow ditch | groove side surface (concave part side), Although it can select suitably according to the objective, 1.5 mm- 4.0 mm and 2 mm to 3 mm are more preferable.
If the maximum distance is less than 1.5 mm, the auxiliary water may hardly flow, and the auxiliary water may overflow from the inside of the recess. If it exceeds 4.0 mm, the curtain film becomes unstable. In some cases, turbulence may occur in the lower part.
However, in the case of a slide die type curtain, when the flow rate of the coating liquid is large, it is necessary to appropriately set the groove width w when the curtain film thickness is larger than the maximum groove interval (w) above the edge guide. is there.

-Support-
The support is not particularly limited as long as it can support the coating liquid, and can be appropriately selected according to the purpose.
There is no restriction | limiting in particular as a shape of the said support body, a structure, and a magnitude | size, According to the objective, it can select suitably.
Examples of the support include release paper, base paper, synthetic paper, and PET film.

<Conveying means, conveying process>
The transport means is a means for transporting a support, and the transport process is a process for transporting the support.

Hereinafter, the curtain coating apparatus and the curtain coating method of the present invention will be described in more detail with reference to the drawings.
The embodiments described below are preferred embodiments of the present invention, and thus various technically preferable limitations are given. However, the scope of the present invention is particularly limited in the following description. Unless otherwise described, the present invention is not limited to these embodiments.

FIG. 2 shows an example of a slide curtain coating apparatus as the curtain coating apparatus of the present invention.
In FIG. 2, a slide curtain coating device (curtain coating head) 7 has slots 10 and 11, manifolds 12 and 13 and slits (not shown) as discharging means for the coating liquid 3, and the coating liquid discharging means The coating liquid 3 is discharged onto the slide surface 8, and the coating liquid 3 flows down on the slide surface 8, freely falls from the slide surface 8 to form the curtain film 6, and continuously runs on the web (base material) 5. A coating film is formed on the substrate. At this time, the web 5 is conveyed using a conveyance means (not shown). A slide portion edge guide (guide means) 9 is disposed on the side surface of the slide surface 8, and a curtain portion edge guide (guide means) 2 that holds both ends of the curtain film 6 is disposed on the side surface of the curtain film 6. It is arranged.

  In the case of simultaneous multilayer coating, the slide curtain coating device (curtain coating head) 7 has a plurality of manifolds 12 and 13 and slots 10 and 11, and the plurality of manifolds 12 and 13 and slots 10 and 11 are coated. The liquid 3 is discharged onto the slide surface 8, and the coating liquid 3 is stacked on the slide surface 8. The laminated coating liquid 3 falls freely from the slide surface 8 to form a curtain film 6, and forms a coating film on a continuously running web (base material) 5.

FIG. 3 is a view showing an example of a slot curtain coating apparatus as the curtain coating apparatus of the present invention.
In FIG. 3, the coating liquid is discharged from the manifold 12 and the slot 10 provided in the slot curtain coating head 1, held at both ends by the edge guide 2, flows down as the curtain film 6, collides with the substrate 5 and is coated. Worn.

As shown in FIG. 4, the coating liquid is discharged from the manifold 3, slot 10 and slit (not shown) provided in the slide curtain coating head 7, flows down the slide surface 8, and holds both ends by the edge guide body 2. Then, it flows down, collides with the substrate 5 and is applied.
In the case of multi-layer simultaneous application, the plurality of manifolds 3, slots 10, and slits (not shown) are provided, and the application liquid is discharged onto the slide surface 8, and the application liquid is stacked on the slide surface 8. The laminated coating liquid freely falls from the slide surface 8 to form a curtain film 6 and forms a coating film on the web 5 that runs continuously.

As shown in FIG. 5, the edge guide main body 2 includes an auxiliary water introduction port 14 that discharges the auxiliary water 15 in the width direction of the auxiliary water flow lower groove (recessed portion) 16 toward the lower side.
The auxiliary water inlet 14 has a rectangular cross-sectional shape, and is arranged perpendicular to the curtain film 6 and perpendicular to the falling direction of the curtain film 6.
The curtain film 6 falls in the direction of the arrow, and both ends thereof are supported by the auxiliary water 15 falling in the auxiliary water flow down groove (recessed portion) 16 of the edge guide body 2.
The introduction speed of the auxiliary water 15 is set by changing the opening degree of a flow control valve (not shown) or the discharge amount of the pump.
The lower portion of the edge guide body 2 is provided with a discharge port (not shown) for discharging the mixed solution of the auxiliary water 15 and the coating solution, and a vacuum mechanism (not shown) for easily discharging the mixed solution. . Further, auxiliary water for preventing the coating liquid from sticking may flow under the edge guide body 2.

  FIG. 6 is a front view of the edge guide body 2, and FIG. 9 is a cross-sectional view of the edge guide body 2. As shown in FIG. 9, W is the maximum distance between the concave side surfaces 16b of the edge guide body 2 (the maximum width of the auxiliary water flow lower groove (recess) 16 and the maximum width of the auxiliary water inlet 14), and h is the auxiliary water flow. The maximum depth of the lower groove (concave portion) 16 was set. The tip 90 makes an acute angle θ. However, due to problems such as processing accuracy, the tip has a flat portion of about 0.1 mm, or the tip has a curved surface (R) of about several tens to 100 μm in order to suppress burrs and burrs. Also good.

Further, as shown in FIG. 7, the gap of the auxiliary water introduction port 14 is set to 0.2 mm, and the joint surface 70 on the upper part of the curtain film and the edge guide and the bottom surface 16 a of the auxiliary water flow down groove (recessed part) 16 are 0. A step of about 2 mm to 0.5 mm is provided.
Inside the edge guide, there are at least one manifold, and the auxiliary water can be uniformly discharged in the width direction. The bottom surface of the auxiliary water flow groove of the edge guide needs to have wettability that allows the auxiliary water to flow uniformly, and when selecting the auxiliary water, it is necessary to select a material as appropriate. For example, a metal surface such as SUS-based, aluminum-based, or hard chrome plating may be used, and any other portion may be a hydrophilic material or a hydrophobic material.
Further, the edge guide (guide means) can be applied to both the slide curtain device (FIG. 2) and the slot curtain device (FIGS. 3 and 4).

  By changing the bottom and side surfaces of the auxiliary water flow down groove from porous material to metal surface, the problem of clogging of the coating liquid into the porous material is solved, and the surface tension of the auxiliary water is not the surface tension of the coating liquid. In order to exhibit alignment, by providing an auxiliary water flow lower groove (concave portion), a stable curtain film can be formed against disturbance caused by wind. Further, by introducing auxiliary water in the falling direction along the edge of the curtain film and introducing the auxiliary water at an initial introduction speed of 0.4 m / second to 1.6 m / second, the boundary layer in the curtain film can be further suppressed. it can.

  However, the auxiliary water does not flow over the entire surface at the lower part of the auxiliary water flow groove (concave), the auxiliary water becomes string-like, the curtain film becomes unstable, and turbulent flow may occur at the lower part of the edge guide. It was. It has been found that this phenomenon is caused by the maximum width W of the auxiliary water flow ditch.

  As for the turbulent flow, the detailed mechanism is unknown, but as shown in FIG. 14, the auxiliary water 15 in contact with the curtain film 6 becomes turbulent at the lower part of the edge guide, and the curtain film is disturbed. When the auxiliary water becomes a turbulent flow, it vibrates violently with the curtain film with which the auxiliary water comes into contact. In addition, it may flow stably in laminar flow, and turbulence is likely to occur in the lower part of the edge guide (when the speed is high), so the Reynolds number in the auxiliary water flow path is considered to be greatly related. Therefore, it is considered that the maximum depth h of the auxiliary water flow down groove (concave portion) that affects the Reynolds number and the maximum width W of the auxiliary water flow down groove are related.

The edge guide according to the present invention can be applied to both a slide curtain as shown in FIG. 2 and a slot curtain as shown in FIGS. However, when the edge guide according to the present invention is applied to a slide curtain, the curvature of the curtain film due to the difference in speed between the slide surface and the free surface (teapot effect) when the free fall liquid film is formed after flowing down the slide surface 8 Need to avoid.
Therefore, a width of at least 3 mm from the auxiliary water inlet to the front of the curtain membrane and a width of at least 1 mm to the rear of the curtain membrane are required, and a width of at least 7 mm is required together with the width of 3 mm of the auxiliary water inlet. Further, in the height direction, a length of at least 5 mm is required at the upper part of the auxiliary water inlet, and about 5 mm to 15 mm is required depending on the flow rate of the coating liquid.
Therefore, as shown in FIG. 12, it is preferable that the upper portion of the edge guide is a plane having a length of 5 mm to 15 mm and a width of 7 mm or more from the lower end of the slide curtain die. Although this plane portion is a metal surface, it may be a hydrophilic or hydrophobic surface, and auxiliary water may flow over the surface.
The auxiliary water inlet 14 needs to be in a straight line (slit) shape perpendicular to the curtain film width direction and perpendicular to the curtain film 6 falling direction.

  EXAMPLES Next, although an Example and a comparative example are given and this invention is demonstrated more concretely, this invention is not restrict | limited to the following Example.

Example 1
Using the slide die type curtain coating apparatus shown in FIG. 2, curtain coating is performed under the following conditions: (i) stability of the curtain film from disturbances such as wind, (ii) presence or absence of turbulence near the edge guide (Iii) The phenomenon that the edge guide auxiliary water does not flow over the entire surface (a phenomenon in which the auxiliary water becomes string-like), the presence / absence of turbulent flow under the edge guide, and (iv) the flow rate distribution in the width direction of the curtain film were evaluated. The evaluation results are shown in Tables 1-6.
The position of the edge guide can be moved, and the curtain dropping position was adjusted to be on one side of the edge guide tip.

<Curtain application conditions>
(1) Coating liquid As the coating liquid, an acrylic emulsion adhesive (product name: X-407-102E-10, manufactured by Seiden Chemical) was used.
The liquid viscosity of the coating solution was measured using a B-type viscometer (product name: Bismetron VS-A1, manufactured by Shibaura System). 3. It was 450 mPa · s when measured under conditions of a rotor × 30 rpm. In the power law, Y = 900X− ^0.26 .
It was 33 mN / m as a result of measuring the platinum plate method static surface tension of the said coating liquid with the FACE automatic surface tension meter CBVP-A3 type | mold (made by Kyowa Interface Science Co., Ltd.).

(2) Flow rate of coating solution The flow rate of the coating solution is 1.75 cc / (cm × sec) (measured with a flow meter for coating solution (trade name: CN015C-SS-440K, manufactured by Oval Corporation)) did.
The curtain film width (curtain drop width) was 230 mm.

(3) Shape, size, and material of edge guide The cross-sectional shape of the edge guide was the shape shown in FIG. 9, and θ in FIG. 9 was 60 °.
The size of the edge guide is as follows. The flow surface length L (FIG. 6) is 145 mm, the maximum gap G (FIG. 6) of the auxiliary water inlet is 0.2 mm, and the maximum width W (FIG. 6) of the auxiliary water inlet is 3 mm. The maximum depth h (FIG. 9) of the auxiliary water flow lower groove (recess) was set to 0.5 mm, and the maximum width W (FIG. 9) of the auxiliary water flow lower groove (recess) was set to 3 mm.
The material of the edge guide was SUS420J2.

(4) Supply of edge guide auxiliary water From a pressurized tank pressurized to 0.2 MPa, a micro motion flow meter (manufactured by Oval Corporation) (flow meter body: E010S-SS-311, transmitter: RFT9739-3MD11, integration Total: EL0122-1332011) and a float type flow meter (Tokyo Instruments Co., Ltd., P100L-4) were supplied to the edge guide. By adjusting the opening and closing of the throttle valve of the float type flow meter and converting from the flow rate, the introduction speed was set to 0.8 m / sec.

<Evaluation method>
As a method for grasping the influence from the disturbance, the wind speed of about 0.5 m / s (measured with an anemone master anemometer MODEL 6141) from the front of the curtain film and the direction of the curtain film is measured. The evaluation was made by applying from the front to the two directions in the vicinity of the edge guide. This wind speed was set assuming the airflow generated around the coating head due to the entrained air of the rotating substrate of the roll, the movement of the operator of the coating machine, and the airflow generated during work such as the gap adjustment around the coating machine. .

(I) Stability of curtain film from disturbances such as wind-Evaluation criteria-
○: Curtain film does not shake ×: Curtain film shakes

(Ii) Presence of turbulent flow in the vicinity of the edge guide -Evaluation criteria-
○: No turbulent flow △: Almost no turbulent flow ×: Occurrence of turbulent flow or problem of auxiliary water flow

(Iii) Edge guide auxiliary water does not flow over the entire surface (a phenomenon in which auxiliary water becomes string-like) and the presence or absence of turbulent flow at the bottom of the edge guide -Evaluation criteria-
○: No turbulence occurs and the flow of auxiliary water does not form a string
Δ: Turbulent flow does not occur and the flow of auxiliary water may be string-like ×: Turbulent flow occurs and the flow of auxiliary water may be string-shaped

(Iv) Flow rate distribution in the width direction of the curtain film -Evaluation conditions-
(A) Falling flow rate measurement position:
(I) Curtain membrane width direction position: Auxiliary water flow is measured at a 2.5 mm pitch from the bottom surface of the auxiliary water flow groove (recess) to the position 20 mm from the bottom surface of the auxiliary water flow groove (recess) to the center of the curtain width direction. Measure the area from the bottom of the lower groove (concave) 20mm from the bottom of the curtain width direction to the auxiliary water flow down groove (concave) to the position of 50mm from the bottom of the auxiliary water flow down to the center of the curtain width direction. The region from the position of 50 mm closer to the center in the curtain width direction to the center in the curtain width direction (125 mm from the bottom of the auxiliary water flow lower groove (concave)) was measured at a pitch of 25 mm.
(Ii) Height direction position of the curtain film: position 140 mm below the upper end of the curtain film (b) Flow rate measuring method: Boiled with a width of 4 mm and a depth of 5 mm produced by bending a 0.1 mm thick SUS304 plate, The curtain liquid film was blocked, and the amount of liquid flowing down was measured by the gravimetric method to obtain the falling flow rate. The measured value was made into a flow distribution by normalization with the value in the width direction from the bottom of the auxiliary water flow down groove (concave) 50 mm to the center in the curtain width direction (125 mm from the bottom of the auxiliary water flow down groove (concave)) as 100%.
-Evaluation criteria-
○: Thickness of the thick film portion is less than 110% of the average value Δ: Thickness of the thick film portion is 110% or more of the average value and less than 120% ×: Thickness of the thick film portion is 120% or more of the average value

(Comparative Example 1)
In the first embodiment, the curtain shape of the edge guide is changed to the shape shown in FIG. 9 except that the shape shown in FIG. 8 is changed to the shape shown in FIG. 8 (θ is 90 ° in FIG. 8). The stability of the coating and (i) the curtain film from disturbances such as wind was evaluated. The evaluation results are shown in Table 1.

(Comparative Example 2)
In Example 1, the cross-sectional shape of the edge guide is changed to the shape shown in FIG. 9 in the same manner as in Example 1 except that the shape of the edge guide is a planar shape having no auxiliary water flow down groove (recessed portion). ) The stability of the curtain film from disturbances such as wind was evaluated. Here, the stability indicates a state in which the curtain film is held by the auxiliary water in the vicinity of the edge guide, and the auxiliary water is held on the side wall of the groove of the edge guide. The evaluation results are shown in Table 1.

In die coating, as shown by the dotted lines in FIGS. 10 and 11, the angle formed by the downstream lip tip of the coating portion 22 is 90 ° (FIG. 11) rather than the obtuse angle (FIG. 10). There is a knowledge that the coating film 20 has a small wetting up and is stable in coating, and streaks are less likely to be generated, and that a sharp angle of less than 90 ° has a further effect.
On the other hand, in the case of the edge guide, the shape shown in FIG. 9 (θ in FIG. 9 is 60 °) is more than the comparative example 1 using the edge guide having the shape shown in FIG. 8 (θ in FIG. 9 is 90 °). In Example 1 using the edge guide, the pinning effect of the edge guide auxiliary water at the tip portion was larger.
In the case of die coating, when the coating film is separated from the lip and the base material and becomes a free surface, it receives a force in only one direction due to the tension received from the base material. The angle formed by the tip of the lip is about 90 °), but in the case of an edge guide, auxiliary water receives forces in two directions, the falling direction and the tension of the curtain film, so θ is set to an acute angle (less than 90 °) It is considered that wetting was suppressed more and the edge guide auxiliary water was easily pinned at the tip.

(Example 2)
In Example 1, the maximum depth h (FIG. 9) of the auxiliary water flow groove (recess) is 0.5 mm, and the maximum depth h (FIG. 9) of the auxiliary water flow groove (recess) is 0.2 mm. Except for this, curtain application and (ii) the presence or absence of turbulent flow in the vicinity of the edge guide were evaluated in the same manner as in Example 1. The evaluation results are shown in Table 2.

(Example 3)
In Example 1, the maximum depth h (FIG. 9) of the auxiliary water flow groove (recess) is 0.5 mm, and the maximum depth h (FIG. 9) of the auxiliary water flow groove (recess) is 0.3 mm. Except for this, curtain application and (ii) the presence or absence of turbulent flow in the vicinity of the edge guide were evaluated in the same manner as in Example 1. The evaluation results are shown in Table 2.

Example 4
In Example 1, the maximum depth h (FIG. 9) of the auxiliary water flow ditch (recess) is 0.5 mm, and the maximum depth h (FIG. 9) of the auxiliary water flow ditch (recess) is 0.6 mm. Except for this, curtain application and (ii) the presence or absence of turbulent flow in the vicinity of the edge guide were evaluated in the same manner as in Example 1. The evaluation results are shown in Table 2.

(Example 5)
In Example 1, the maximum depth h (FIG. 9) of the auxiliary water flow groove (recess) is 0.5 mm, and the maximum depth h (FIG. 9) of the auxiliary water flow groove (recess) is 0.1 mm. Except for this, curtain application and (ii) the presence or absence of turbulent flow in the vicinity of the edge guide were evaluated in the same manner as in Example 1. The evaluation results are shown in Table 2.

(Example 6)
In Example 1, the maximum depth h (FIG. 9) of the auxiliary water flow groove (recess) is 0.5 mm, and the maximum depth h (FIG. 9) of the auxiliary water flow groove (recess) is 0.7 mm. Except for this, curtain application and (ii) the presence or absence of turbulent flow in the vicinity of the edge guide were evaluated in the same manner as in Example 1. The evaluation results are shown in Table 2.

In Examples 1 to 3, turbulent flow was not generated, and in Example 4, turbulent flow was sometimes generated. In Example 5, the edge guide auxiliary water may overflow in the upper part, and in Example 6, turbulent flow may occur in the lower part and the curtain film may be disturbed.
From Table 2, it can be seen that the maximum depth h (FIG. 9) of the auxiliary water flow ditch (recess) is related to the occurrence of turbulence near the edge guide of the curtain film. It was found that the depth h (FIG. 9) is preferably 0.2 mm to 0.5 mm.

(Example 7)
In Example 1, the maximum width W (FIG. 9) of the auxiliary water flow groove (recess) is 3 mm, except that the maximum width W (FIG. 9) of the auxiliary water flow groove (recess) is 1.5 mm. In the same manner as in Example 1, the curtain coating and (iii) edge guide auxiliary water did not flow over the entire surface (a phenomenon in which auxiliary water became string-like) and the presence / absence of turbulent flow under the edge guide were evaluated. The evaluation results are shown in Table 3.

(Example 8)
In Example 1, the maximum width W (FIG. 9) of the auxiliary water flow groove (recess) is 3 mm, except that the maximum width W (FIG. 9) of the auxiliary water flow groove (recess) is 4 mm. In the same manner as in No. 1, the curtain coating and (iii) edge guide auxiliary water did not flow over the entire surface (a phenomenon in which auxiliary water became string-like) and the presence / absence of turbulent flow under the edge guide were evaluated. The evaluation results are shown in Table 3.

Example 9
In Example 1, the maximum width W (FIG. 9) of the auxiliary water flow groove (recess) is 3 mm, except that the maximum width W (FIG. 9) of the auxiliary water flow groove (recess) is 5 mm. In the same manner as in No. 1, the curtain coating and (iii) edge guide auxiliary water did not flow over the entire surface (a phenomenon in which auxiliary water became string-like) and the presence / absence of turbulent flow under the edge guide were evaluated. The evaluation results are shown in Table 3.

(Example 10)
In Example 1, the maximum width W (FIG. 9) of the auxiliary water flow groove (recess) is 3 mm, except that the maximum width W (FIG. 9) of the auxiliary water flow groove (recess) is 7 mm. In the same manner as in No. 1, the curtain coating and (iii) edge guide auxiliary water did not flow over the entire surface (a phenomenon in which auxiliary water became string-like) and the presence / absence of turbulent flow under the edge guide were evaluated. The evaluation results are shown in Table 3.

(Example 11)
In Example 1, the maximum width W (FIG. 9) of the auxiliary water flow groove (recess) is 3 mm, except that the maximum width W (FIG. 9) of the auxiliary water flow groove (recess) is 1 mm. In the same manner as in No. 1, the curtain coating and (iii) edge guide auxiliary water did not flow over the entire surface (a phenomenon in which auxiliary water became string-like) and the presence / absence of turbulent flow under the edge guide were evaluated. The evaluation results are shown in Table 3.

(Example 12)
In Example 1, the maximum width W (FIG. 9) of the auxiliary water flow groove (recess) is 3 mm, except that the maximum width W (FIG. 9) of the auxiliary water flow groove (recess) is 8 mm. In the same manner as in No. 1, the curtain coating and (iii) edge guide auxiliary water did not flow over the entire surface (a phenomenon in which auxiliary water became string-like) and the presence / absence of turbulent flow under the edge guide were evaluated. The evaluation results are shown in Table 3.

The phenomenon that the auxiliary water is stabilized by being biased toward the side surface of the edge guide occurs because the thickness of the curtain film is smaller than the maximum width W of the auxiliary water flow down groove (recessed portion). It was considered that there was an effect of stabilizing the curtain film by narrowing the maximum width W of the auxiliary water flow lower groove of the guide. In addition, since the state where the auxiliary water is biased toward the side of the edge guide is stable, the curtain film is formed by narrowing the maximum width W of the auxiliary water flow down groove (recess) until the both ends of the auxiliary water can be held by the side of the recess. Thought to stabilize.
In Examples 1, 7 and 8, the curtain water flowed undisturbed, and the auxiliary water flowed across the bottom surface of the auxiliary water flow lower groove. In Examples 9 and 10, the curtain film flowed without disturbance, but the auxiliary water did not flow down on the entire surface.
In Example 11, the flow of the auxiliary water sometimes deteriorated, and the auxiliary water sometimes overflowed.
In Example 12, turbulent flow sometimes occurred in the lower part.
From Table 3, it can be seen that the maximum distance between the recess side surfaces (maximum width of the auxiliary water flow down groove (recess)) W affects the flow of the auxiliary water, and the curtain film is further stabilized by setting it to 1.5 mm to 4 mm. I found out that

(Example 13)
In Example 1, the auxiliary water introduction speed is set to 0.8 m / sec (corresponding flow rate supply: 50 cc / min), while the auxiliary water introduction speed is set to 0.4 m / sec (corresponding flow rate supply: 25 cc / min). Except for the above, in the same manner as in Example 1, the curtain coating and (iv) the flow rate distribution in the width direction of the curtain film were evaluated. The evaluation results are shown in Table 4.

(Example 14)
In Example 1, the auxiliary water introduction speed is set to 0.8 m / sec (corresponding flow rate supply: 50 cc / min), and the auxiliary water introduction speed is 1.6 m / sec (corresponding flow rate supply: 100 cc / min). Except for the above, in the same manner as in Example 1, the curtain coating and (iv) the flow rate distribution in the width direction of the curtain film were evaluated. The evaluation results are shown in Table 4.

(Example 15)
In Example 1, the auxiliary water introduction speed is set to 0.8 m / sec (corresponding flow rate supply: 50 cc / min), and the auxiliary water introduction speed is 1.7 m / sec (corresponding flow rate supply: 106 cc / min). Except for the above, in the same manner as in Example 1, the curtain coating and (iv) the flow rate distribution in the width direction of the curtain film were evaluated. The evaluation results are shown in Table 4.

(Example 16)
In Example 1, the auxiliary water introduction speed is set to 0.8 m / sec (corresponding flow rate supply: 50 cc / min), while the auxiliary water introduction speed is 2.0 m / sec (corresponding flow rate supply: 125 cc / min). Except for the above, in the same manner as in Example 1, the curtain coating and (iv) the flow rate distribution in the width direction of the curtain film were evaluated. The evaluation results are shown in Table 4.

(Example 17)
In Example 1, the auxiliary water introduction speed is set to 0.8 m / sec (corresponding flow rate supply: 50 cc / min), while the auxiliary water introduction speed is 2.1 m / sec (corresponding flow rate supply: 131 cc / min). Except for the above, in the same manner as in Example 1, the curtain coating and (iv) the flow rate distribution in the width direction of the curtain film were evaluated. The evaluation results are shown in Table 4.

(Example 18)
In Example 1, the auxiliary water introduction speed is set to 0.8 m / sec (corresponding flow rate supply: 50 cc / min), while the auxiliary water introduction speed is set to 0.2 m / sec (corresponding flow rate supply: 12.5 cc / min). Except for the above, the application of curtains and (iv) the flow rate distribution in the width direction of the curtain film were evaluated in the same manner as in Example 1. The evaluation results are shown in Table 4.

(Example 19)
In Example 1, the auxiliary water introduction speed is set to 0.8 m / sec (corresponding flow rate supply: 50 cc / min), and the auxiliary water introduction speed is 0.35 m / sec (corresponding flow rate supply: 22 cc / min). Except for the above, in the same manner as in Example 1, the curtain coating and (iv) the flow rate distribution in the width direction of the curtain film were evaluated. The evaluation results are shown in Table 4.

(Example 20)
In Example 1, the auxiliary water introduction speed is set to 0.8 m / sec (corresponding flow rate supply: 50 cc / min), while the auxiliary water introduction speed is set to 2.5 m / sec (corresponding flow rate supply: 156 cc / min). Except for the above, in the same manner as in Example 1, the curtain coating and (iv) the flow rate distribution in the width direction of the curtain film were evaluated. The evaluation results are shown in Table 4 and FIG.

In Table 4, the numbers in the thick film section indicate the difference between the distance in the curtain width direction from the bottom of the auxiliary water flow lower groove at the measurement point with the largest flow rate and the reference value (100%). The numbers indicate the difference between the distance in the curtain width direction from the bottom surface of the auxiliary water flow lower groove (concave) at the measurement point with the smallest flow rate and the reference value (100%).
In addition, since the edge guide auxiliary water was discharged obliquely downward in Example 20, it was not included in the evaluation.

  From Table 4, when Examples 1 and 13 to 17 and Examples 18 and 19 are compared, in any case, the thick film portion is formed at a position of 10 mm to 25 mm from the bottom surface of the auxiliary water flow down groove (concave portion). In Examples 1 and 13 to 17, it was found that the flow rate of the thick film portion was reduced by about 10% compared to Examples 18 and 19. Moreover, in Examples 1 and 13 to 17 and Examples 18 and 19, it was found that the thin film portion was in an improving trend. By gradually increasing the introduction speed of the auxiliary water from 0.2 m / sec, the film thickness of the curtain film can be suppressed. However, at about 2.0 m / sec or more, the thick film can be increased even if the speed is increased further. There is no significant difference in the effect of suppression. Accordingly, it was found that the auxiliary water introduction speed is preferably 0.4 m / second to 2.0 m / second.

(Example 21)
In Example 1, instead of using the slide die type curtain coating apparatus shown in FIG. 2, the curtain coating and (iv) were performed in the same manner as in Example 1 except that the slot die type curtain coating apparatus shown in FIG. 3 was used. ) The flow rate distribution in the width direction of the curtain film was evaluated. The evaluation results are shown in Table 5 and FIG.

Example 1 is a flow rate profile in a slide curtain. Due to the influence of the boundary layer in the lower part of the slide flow, there is already a thick part at the time of curtain film formation, and it is difficult to further suppress the thick part. Therefore, a slot curtain was employed as in Example 21 in order to further reduce the thickness and thickness. As a result, as shown in FIG. 16, the thick film portion is not formed, the extreme thin film portion is not formed, and the total width is within ± 4%.
Since the thick film portion can be further reduced in the slot curtain, it is possible to suppress the thickening of the curtain film by suppressing the boundary layer in the falling portion of the curtain film.

  Moreover, about Example 1, 13, 14 and 18, the fall speed in the height position of 10 mm and 140 mm from the slide die lower end was measured with the fall speed measuring device (Laser Doppler non-contact speedometer: Act Electronics, model MODEL 1110A). Measurements were made to examine how the boundary layer as shown in FIG. 14 near the edge guide changes and how it affects the film thickness distribution of the curtain film. The results are shown in Table 6 and FIGS.

  From Table 6 and FIGS. 17 and 18, when Examples 1, 13 and 21 are compared with Example 18, Examples 1, 13 and 21 are while flowing down the slide portion of the slide die more than Example 18. It was found that the velocity distribution of the curtain film formed on the film was canceled while the curtain film dropped, and the thick film portion could be suppressed.

From the above, it has been found that the edge guide auxiliary water does not flow over the entire surface, eliminates the phenomenon of being biased toward the edge, suppresses the turbulent flow of the curtain film, and stabilizes the curtain film from disturbance due to wind.
Further, by setting the auxiliary water introduction speed to 0.4 m / second to 2.1 m / second, the boundary layer can be reduced to an extremely small level, and the formation of the boundary layer can be suppressed or controlled. It has been found that by eliminating the boundary layer, it is possible to suppress thickening and thinning.

  The curtain coating apparatus and the curtain coating method of the present invention are suitably used for the production of, for example, silver halide photographic light-sensitive materials, magnetic recording materials, pressure / heat-sensitive recording paper, art paper, coated paper, and ink jet recording sheets.

2 Curtain edge guide (guide means)
3 Coating liquid 5 Web (base material)
6 Curtain film 8 Slide surface 9 Slide part edge guide (guide means)
10 Slot 11 Slot 12 Manifold 13 Manifold 14 Auxiliary water inlet 16 Auxiliary water flow down groove (concave)
16a Concave bottom 16b Concave side 21 Edge guide exposed surface

Japanese Patent No. 2630512 JP-A-1-199668 Special table 2008-529753 gazette US Patent No. 7081163

Claims (12)

A discharge means having a coating liquid discharge port for discharging the coating liquid;
An auxiliary water introduction port for introducing auxiliary water, supporting both ends of the curtain film in a width direction substantially perpendicular to the flow-down direction of the curtain film by the coating liquid, and the curtain film on the transported support A pair of guiding means for guiding
Conveying means for conveying the support,
Each of the pair of guide means is perpendicular to a recess formed by an auxiliary water flow groove for allowing the auxiliary water to flow on a surface of the pair of guide means on the side guiding the curtain film, and to a bottom surface of the recess. And a recessed side surface formed on
A curtain coating apparatus characterized in that the side surface of the concave portion and an exposed surface formed continuously and intersecting with the side surface of the concave portion form an acute angle.   The curtain coating apparatus according to claim 1, wherein the maximum depth of the concave portion is 0.2 mm to 0.5 mm.   The curtain coating apparatus according to any one of claims 1 to 2, wherein a maximum distance between the side surfaces of the recesses is 1.5 mm to 4.0 mm.   The curtain according to any one of claims 1 to 3, wherein the guide means has a flat surface above the auxiliary water inlet in the auxiliary water flow direction, and the flat surface is a rectangle having a length of 5 mm to 15 mm and a width of 7 mm or more. Coating device.   The curtain coating apparatus according to any one of claims 1 to 4, wherein the auxiliary water introduction speed is 0.4 m / sec to 2.1 m / sec.   The curtain coating apparatus according to any one of claims 1 to 5, wherein a maximum interval of the auxiliary water introduction port with respect to the flow direction of the auxiliary water is 0.2 mm to 0.5 mm. A discharge step of discharging the coating liquid from the coating liquid discharge port;
A pair of guide means having an auxiliary water introduction port for introducing auxiliary water supports both ends of the curtain film in the width direction substantially perpendicular to the flow direction of the curtain film by the coating liquid, and transports the curtain film. A guiding step for guiding the formed support;
A conveying step of conveying the support,
Each of the pair of guide means is perpendicular to a recess formed by an auxiliary water flow groove for allowing the auxiliary water to flow on a surface of the pair of guide means on the side guiding the curtain film, and to a bottom surface of the recess. And a recessed side surface formed on
A curtain coating method , wherein the concave side surface and an exposed surface formed continuously and intersecting with the concave side surface form an acute angle.   The curtain coating method according to claim 7, wherein the maximum depth of the recess is 0.2 mm to 0.5 mm.   The curtain coating method according to any one of claims 7 to 8, wherein the maximum distance between the side surfaces of the recesses is 1.5 mm to 4.0 mm.   The curtain according to any one of claims 7 to 9, wherein the guide means has a flat surface above the auxiliary water inlet in the auxiliary water flow direction, and the flat surface is a rectangle having a length of 5 mm to 15 mm and a width of 7 mm or more. Application method.   The curtain coating method according to any one of claims 7 to 10, wherein the auxiliary water introduction speed is 0.4 m / sec to 2.1 m / sec.   The curtain coating method according to any one of claims 7 to 11, wherein a maximum interval of the auxiliary water introduction port in the flow direction of the auxiliary water is 0.2 mm to 0.5 mm.