JP2003010765A - Coating apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating apparatus by which spot like defect is suppressed. SOLUTION: In the coating apparatus for applying a coating material discharged from a slit of a dye head 30 of an extrusion type die, at least two auxiliary rolls 8 and 8 rotating in contact with a back up roll 90 are provided on the surface of the backup roll and a lip of the die head is arranged in the vicinity of a supporting body traveling between the auxiliary rolls.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a coating apparatus.

[0002]

2. Description of the Related Art Conventionally, there are various coating methods in a coating process for coating a support. The coating method is roughly classified into two. One is a pre-measurement type coating method in which the coating material is discharged in an amount to form a required coating film and the coating material is applied to the support, and the other is a surplus coating material that is more than the required coating film formation amount in advance. This is a post-measurement type coating method in which the excess amount is discharged on top and then the excess is removed by some scraping means. Examples of the post-measurement type coating method include a blade type coating method, an air knife type coating method, and a wire bar type coating method. In addition, as a pre-weighing type coating method,
Extrusion type coating system, curtain type coating system,
A slide type coating method and the like can be mentioned.

For coating in the manufacturing process of photographic light-sensitive materials and the like, the extrusion type coating method is adopted because of its high coating accuracy, high quality, and difficulty in receiving the influence of the support (wrinkles, cracks, etc.). There were many

The coating apparatus used in the extrusion type coating system forms a coating film uniformly on the support,
It is composed of a so-called die head for supplying paint and a backup roll for uniformly holding the surface of a continuously running support. The coating method is a method in which the coating liquid is discharged from the tip of the slit of the die head to form a bead (liquid pool) on a continuously running support, and the die head combines two or more blocks to supply the coating liquid. It has a supply port, a manifold to temporarily store the supplied paint in the width direction, and a slit to evenly discharge the paint from the manifold, and it is possible to apply from a single layer to multiple layers depending on the number of blocks combined. Is a different coating method.

Regarding the extrusion type coating method, JP-A-56-95363 and JP-A-50-142643 are used.
Many techniques are disclosed, such as a single-layer coating method disclosed in each of the publications, etc., and a multi-layer coating method disclosed in JP-A-45-12390 and 46-236. .

In the above-mentioned coating, since the support is wound around the backup roll, the die head lip portion is brought close (usually in the range of 40 μm to 1 mm) and the coating material is discharged to perform the coating. If dust or foreign matter adheres to the back of the body (contact surface of the backup roll), or if dust or foreign matter also adheres to the backup roll, the gap (gap between the lip and the support) will change. Resulting in.

If the gap changes, the thickness of the paint film on the support changes only in that part (generally becomes thinner).
However, if the rate of change of the gap is large, there is a problem that coating defects such as cissing and scratches on the coating liquid tend to occur.

Therefore, in the field of photographic light-sensitive materials, the manufacturing process is often a clean environment. However, even when working in a clean environment, it may be brought in from the human body or dust may be generated from the fan, motor, etc., causing the above-mentioned coating defect.

When such spot-shaped coating defects flow out, they are cut off because they cause image defects and the like.
Product loss and labor cost loss accompanying this are very large. Furthermore, if dust adheres to the backup roll and remains attached to the backup roll during transport of the support for some reason, the backup roll circle The paint film was liable to break down in a long cycle, and there was a significant risk of product loss.

As a method of removing dust from a traveling support, Japanese Patent Publication No. 7-4583 proposes a method in which a blow-out nozzle having an edge is brought close to the support so that an adhering substance on one surface of the support is separated by the edge while the support is levitated. A body dust removal method is disclosed.

However, in the method described above, there is no risk of scratches on the support, but there is a possibility that foreign matter that cannot be completely removed will remain, and that foreign matter that has adhered to the backup roll will not be removed. There was a problem.

[0012]

SUMMARY OF THE INVENTION An object of the present invention is to provide a coating apparatus with few spot-like defects.

[0013]

The above objects of the present invention have been achieved by the following items 1 to 8.

1. In the coating device, which is held by a backup roll and is continuously traveling, the coating material applied from the slit of the die head of the extrusion type die, which is installed facing the backup roll, is applied to the backup surface. At least two auxiliary rolls A and B are provided on the roll surface to rotate in contact with the backup roll, and the lip of the die head is provided in the vicinity of the support running between the auxiliary rolls A and B. A coating device characterized by being arranged.

2. The diameter of the auxiliary roll A or the auxiliary roll B is adjusted to be 1% or more and 20% or less of the diameter of the backup roll, and the variation in the diameter of the auxiliary roll A or the auxiliary roll B in the width direction is 2 %
The coating device as described in the above item 1, characterized in that:

3. In the coating device, which is held by a backup roll and is continuously traveling, the coating material applied from the slit of the die head of the extrusion type die, which is installed facing the backup roll, is applied to the backup surface. A groove is provided in the width direction of the roll surface, and a lip of the die head is arranged in the vicinity of the support running on the groove.

4. 4. The coating apparatus according to the above 3, wherein the depth of the groove in the width direction of the backup roll surface is 50 μm or more, the circumferential length of the backup roll is 5 mm or more, and the backup roll is fixed. .

5. In a coating apparatus for coating a coating material discharged from a slit of a die head of an extrusion type die, which is installed facing the backup roll, on the surface of a support which is held by the backup roll and is running continuously, the backup An applicator characterized in that the roll surface is covered with rubber.

6. The thickness of the rubber covering the backup roll is 1 mm or more, and the hardness of the rubber is JIS B 7
Shore D hardness defined by 727 is 20 to 90,
Further, the coating apparatus according to the above 5, wherein the variation of the diameter of the backup roll in the width direction of the backup roll in the state covered with the rubber is 2% or less.

7. In the coating device, which is held by a backup roll and is continuously traveling, the coating material applied from the slit of the die head of the extrusion type die, which is installed facing the backup roll, is applied to the backup surface. An applicator characterized in that the roll surface has convex portions over the entire surface.

8. 8. The coating apparatus according to 7, wherein the projections on the backup roll surface have a height of at least 50 μm or more with respect to the backup roll surface, and the intervals between the projections are 100 μm or more.

The present invention will be described in detail below. As a result of various studies on the above problems, the inventors of the present invention have carried out a die head of an extrusion type die, which is installed on a surface of a support which is held by a backup roll and is continuously running so as to face the backup roll. In the coating device for coating the coating material discharged from the slit, at least two auxiliary rolls A and B that rotate in contact with the backup roll are provided on the surface of the backup roll as described in claim 1. And a coating device in which the lip of the die head is arranged in the vicinity of the support body that travels between the auxiliary roll A and the auxiliary roll B (here, the vicinity of the support body means the closest portion of the die head lip and the support body. Distance to 4
It shows that it is 0 μm to 1 mm. ) As described in claim 3, a coating device in which a groove is provided in the width direction of the backup roll surface, and the lip of the die head is arranged in the vicinity of the support running on the groove. A coating device having a backup roll surface covered with rubber as described above, or a coating device having a backup roll surface having a convex portion over the entire surface thereof as described in claim 7, and a coating device having each of the above configurations. Depending on the device, dust, foreign matter existing between the backup roll surface and the back surface of the support,
It was possible to significantly reduce spot-like defects in the coating film due to minute projections.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

First, a conventional extrusion type coating apparatus will be described with reference to FIG. FIG. 1 is a schematic cross-sectional view showing a conventional extrusion type coating apparatus.

In FIG. 1, the support 1 travels while being held by a backup roll 2 via a support cleaning means (web cleaner, etc.) from an unwinding part (not shown), passes through a paint film drying chamber (not shown), and is wound up. To be At that time, the coating material 4 is applied onto the support 1 by the die head 30 arranged so as to face the backup roll 2. still,
Although not shown here, it is common to have a mechanism for removing or preventing the thick film portion at the coating start portion and the coating end portion, which causes problems such as roll contamination due to undried coating film in the coating process. is there.

Next, the die head used in the extrusion type coating apparatus will be described with reference to FIGS. 2 (a) and 2 (b).

FIG. 2A is a schematic sectional view of the central portion of the die head, and FIG. 2B is a schematic sectional view of the die head as seen from above.

In FIG. 2A, the die head 30 has slits 31 for uniformly spreading the coating in the width direction of the support.
It comprises a manifold 32 for accumulating the paint inside, a supply port 33 for conducting the paint in the manifold, and a lip 34 facing the backup roll and pressing the paint. The lip 34 is divided into an upstream side and a downstream side with the slit 31 interposed therebetween. When the manifold 32 and the slit 31 are provided in the entire width of the die head, it is preferable to install the side plate 35.

The die head 30 may be composed of a combination of two or more blocks (the combination is by a bolt, a hydraulic jack, etc.).

FIG. 3 (a) is a schematic sectional view showing one embodiment of the coating apparatus of the present invention, and FIG. 3 (b) shows the vicinity of the backup roll, auxiliary roll and die in FIG. 3 (a). It is an expanded schematic sectional view shown.

Two auxiliary rolls 8 shown in FIG. 3 (a)
Is arranged in contact with the backup roll 90 and can rotate in accordance with the rotation of the backup roll 90. The backup roll 90 is rotating in the direction opposite to the rotation direction shown in FIG. At this time, the lip 34 (also referred to as the die head lip 34) is brought close to the support 1 between the auxiliary rolls 8 to perform the coating. Auxiliary roll 8
May be made of the same material as the backup roll 90 or may be made of a different material. The diameter of the auxiliary roll 8 is preferably 1% or more and 20% or less of the diameter of the backup roll 90, and the diameter variation of both the backup roll 90 and the auxiliary roll 8 is preferably adjusted to 2% or less in the coating width direction. In FIG. 3B, the distance x between the auxiliary rolls 8 is preferably larger than the sum of the upstream lip length and the downstream lip length of the lip 34 and the total length of the slits 31.

FIG. 4A is a schematic sectional view showing another embodiment of the coating apparatus of the present invention, which is characterized by using a backup roll 90 having a groove 91 on the surface. When this backup roll 90 is used, when the support 1 is conveyed, the backup roll 90 is fixed and the die head lip 3 is attached to the support 1 running on the groove 91.
4 is made to approach, and coating is performed. Here, the backup roll 90 is fixed and is not rotated.

FIG. 4B is an enlarged schematic sectional view of the vicinity of the die head lip 34. The depth of the groove 91 on the surface of the backup roll 90 is the length of the portion shown by the arrow a in the figure, and is 50 from the viewpoint of obtaining the effect described in the present invention.
It is preferable to adjust the thickness to 1 μm or more and 1 mm or less.
The circumferential length of the upper surface groove 91 of the backup roll 90 is the length of the portion indicated by the arrow b in the figure, and is 5 mm or more 1
It is preferable to adjust it to 0 mm or less.

FIG. 5 is a schematic sectional view showing another embodiment of the coating apparatus of the present invention, which is characterized in that the surface of the backup roll 100 is covered with rubber 101.

From the viewpoint of obtaining the effect described in the present invention, the rubber 101 to be wound has a thickness of 1 mm to 3 m.
It is preferable to adjust to m or less, and the shore D hardness of the rubber 101 specified by JIS B 7727 is 20.
It is preferably adjusted to fall within the range of 90.
Further, it is preferable that the diameter of the backup roll 100 covered with the rubber 101 varies in the coating width direction by 2% or less.

FIG. 6 is a schematic sectional view showing another embodiment of the coating apparatus of the present invention, which is characterized in that the surface of the backup roll 110 has a convex portion over its entire surface.

From the viewpoint of preferably obtaining the effect described in the present invention, the convex portion of the surface of the backup roll 110 is the surface of the backup roll (specifically, the surface of the backup roll formed between the convex portion and the convex portion). ) For 50μ
The height is preferably not less than m and not more than 500 μm, and further, it is preferable that the protrusions are provided at a distance of not less than 100 μm and not more than 2 mm.

Here, the height of the convex portion and the interval between the convex portion and the convex portion described above are the surface roughness meter Surfcoder (manufactured by Kosaka Laboratory).
Was measured using.

The support according to the present invention will be described. The type of the support according to the present invention is not particularly limited, for example,
Paper, plastic film, metal sheet or the like can be used. Examples of the paper include resin-coated paper and synthetic paper. As the plastic film, a polyolefin film (eg, polyethylene film, polypropylene film, etc.), a polyester film (eg, polyethylene terephthalate film, polyethylene 2,6-naphthalate film, etc.), a polyamide film (eg, polyether ketone film etc.) , Cellulose acetate film (eg, cellulose triacetate film) and the like. An aluminum plate is a typical metal sheet. Further, there is no particular limitation on the thickness and width of the support used.

The coating material according to the present invention will be described. Here, the paint used is not particularly limited, and for example, paints for general and industrial silver halide photosensitive materials, paints for heat-sensitive materials, paints for photothermographic materials, or polymer materials for organic solvents, water, etc. Liquids, pigment dispersions, colloidal dispersions and the like. It should be noted that all paints are preferably filtered before the paint is applied to the support. In this filtration, it is preferable to pass a filter medium having an absolute filtration accuracy or a quasi-absolute filtration accuracy of 5 to 50 μm at least once.

The die head according to the present invention will be described. The size of the die head according to the present invention is arbitrary and is not particularly limited, and the material can be selected according to the properties of the coating material and the required machining accuracy. The shape and size of the manifold are not particularly limited and can be set arbitrarily.
The gap value of the slit is determined from the physical properties such as the viscosity of the coating material, but usually the range of 0.05 mm to 2 mm is preferable. However, the variation of the gap value in the coating width direction is preferably 2% or less. The size of the supply port is arbitrary, and its position is usually the center in the die head coating width direction. The lips may have the same length or different lengths on the upstream side and the downstream side. The length is preferably in the range of usually 0.5 mm to 3 mm.

Usually, the die head is preferably provided with a stage for moving to the coating position and the standby position and a liquid receiving chamber for receiving the outflow of the coating material at the standby position. The paint is introduced into the die head through the paint feed pipe. At that time, a pump for sending paint,
It is preferable to use a filtering device for removing foreign matters and impurities in the paint. Similar to the die head, the material of the paint delivery pipe and the liquid receiving chamber is selected according to the properties of the paint and the required machining accuracy. The liquid receiving chamber is provided at a position where it does not come into contact with the backup roll when it is at the coating position, and the pressure may be reduced during coating depending on the properties of the coating material and the necessity of coating. Further, it is preferable that the slit intermediate extension line of the die head faces the center of the backup roll.

Further, as a coating method using the die head, the die head is in a standby position sufficiently distant from the coating position, and the coating liquid is fed at a specified flow rate by a pump to perform preparatory work such as slit cleaning and lip cleaning. After that, coating is started by moving the support at a specified speed and then moving the stage to move the coating device to a predetermined coating position.

At the end of coating, the stage is moved to move the coating device to a predetermined standby position.
Incidentally, the paint may be temporarily stopped or may be stopped during the movement.

[0045]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited thereto.

Example 1 << Composition of paint >> Cellulose acetate (10% methyl ethyl ketone solution) 20 ml / m ² matting agent: Monodisperse silica having a monodispersity of 15% and an average particle size of 10 μm 30 mg / m ² C ₉ H ₁₉ − C ₆ H ₄ —SO ₃ H 10 mg / m ² << Preparation of coating sample 1 >> Using a coating device as shown in FIG. 1, a coating material having the above composition was put on a commercially available support with a width of 500 mm and a thickness using an extrusion die head. A coated sample 1 was prepared by coating a single side of 100 μm polyethylene terephthalate (hereinafter abbreviated as PET) for 2000 m with a width of 480 mm so that the dry film thickness was 5.5 μm.

The coating was carried out at a support traveling speed of 50 m / min, and the coating was dried at 60 ° C. for 10 minutes. The die head used had a slit gap of 500 μm and an upstream lip length of 1 m.
m, downstream lip length 1 mm. The narrowest gap between the support and the die head lip was set to 100 μm.
The backup roll used had a diameter of 200 mm.

<< Preparation of Coating Samples 2 to 5 >> Coating Sample 2 was prepared in the same manner as in Preparation of Coating Sample 1 except that backup rolls as shown in Table 1 were used and coating was carried out by 2000 m. ~ 5 were produced respectively. However, PET used in each backup roll in Table 1
Purchased and used the same lot. Application sample 2
Even in the production of No. 5, the diameter of the backup roll is 20
The thing of 0 mm was used.

<< Evaluation of Spot-like Defects >> For each of the obtained coating samples 1 to 5, 500 samples from a sample of 2000 m
Sampling is performed every 1m for every 1m (total 5 sheets = 5
m × 0.48 m = 24 m ² ) The number of spot-like defects was visually observed. The results obtained are shown in Table 1.

[0050]

[Table 1]

It is clear from Table 1 that the sample of the present invention has very few spot-like defects as compared with the comparison.

[0052]

According to the present invention, a coating apparatus with few spot defects can be provided.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing a conventional extrusion type coating apparatus.

FIG. 2A is a schematic cross-sectional view of a central portion of the die head, and FIG. 2B is a schematic cross-sectional view of the die head as seen from above.

FIG. 3A is a schematic cross-sectional view showing one embodiment of the coating apparatus of the present invention, and FIG. 3B is an enlarged schematic cross-sectional view showing the vicinity of a backup roll, an auxiliary roll and a die.

4A is a schematic sectional view showing another embodiment of the coating apparatus of the present invention, and FIG. 4B is a die head lip 34.
The enlarged schematic sectional drawing of the vicinity is shown.

FIG. 5 is a schematic cross-sectional view showing another form of the coating apparatus of the present invention.

FIG. 6 is a schematic cross-sectional view showing another form of the coating apparatus of the present invention.

[Explanation of symbols]

1 support 2, 90, 100, 110 Backup roll 4 paint 5 stages 6 Liquid receiving chamber 7 Paint delivery pipe 8 auxiliary rolls 30 die head 31 slits 32 manifold 33 Supply port 34 Lip 35 Side plate

Claims (8)

[Claims] 1. A coating method for applying a coating material discharged from a slit of a die head of an extrusion type die, which is installed facing a backup roll, on a surface of a support which is held by a backup roll and is running continuously. In the apparatus, at least two auxiliary rolls A and B that rotate in contact with the backup roll are provided on the surface of the backup roll. The auxiliary roll A and the auxiliary roll B are provided.
A coating apparatus, wherein a lip of the die head is arranged in the vicinity of the support that runs between the two. 2. The diameter of the auxiliary roll A or the auxiliary roll B is adjusted so as to be 1% or more and 20% or less of the backup roll diameter, and the auxiliary roll A or the auxiliary roll B has a diameter in the width direction. The coating device according to claim 1, wherein variation in diameter is 2% or less. 3. A coating method for applying a coating material discharged from a slit of a die head of an extrusion type die, which is supported by a backup roll and continuously running, to a surface of a support body which is continuously running. In the apparatus, a groove is provided in the width direction of the surface of the backup roll, and the lip of the die head is arranged in the vicinity of the support running on the groove. 4. The depth of the groove in the width direction of the backup roll surface is 50 μm or more, the circumferential length of the backup roll is 5 mm or more, and the backup roll is fixed. 3. The coating apparatus according to item 3. 5. A coating for applying a coating material discharged from a slit of a die head of an extrusion type die, which is held facing a backup roll and continuously running, to a surface of the support, which is installed facing the backup roll. In the apparatus, the surface of the backup roll is covered with rubber, and the coating apparatus. 6. The thickness of the rubber covering the backup roll is 1 mm or more, and the hardness of the rubber is JIS B 77.
The Shore D hardness defined by No. 27 is 20 to 90, and the variation of the backup roll diameter in the width direction of the backup roll in the state covered with the rubber is 2% or less. The coating device according to claim 5. 7. A coating method for applying a coating material discharged from a slit of a die head of an extrusion type die, which is supported by a backup roll and continuously running, to a surface of a support body which is continuously running. The coating apparatus is characterized in that the backup roll surface has a convex portion over the entire surface. 8. The projections on the surface of the backup roll have a height of at least 50 μm or more with respect to the backup roll surface, and the intervals between the projections are 100 μm or more. The coating device according to 1.