JP2002001197A - Method and device for rod coating - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the edge of a coating film from becoming thinner or thicker sharply compared to the thickness in the center part. SOLUTION: The transfer coating of a coating liquid 14 or the scraping of excess part of the coating liquid is performed by coating rods 28, 43 in a state that the uncoated part 12A of the end part of a web 12 is lifted up higher than the coated part in the center part of the web 12, where the coating film A is to be formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for coating a rod, using a coating rod as a medium for recording various images or data such as a magnetic tape, a photographic film, and a photographic paper. The present invention relates to a rod coating method and apparatus for coating a flexible belt-like support (hereinafter, referred to as “web”) with a rod.

[0002]

2. Description of the Related Art Methods for obtaining a coating film having a desired thickness on a web include a rod coating method (also referred to as a bar coating method), a reverse roll coating method, a gravure roll coating method, and an extrusion coating method. Among them, the rod coating method is widely used because the equipment is simple and thin layer coating is possible.

The rod coating methods are roughly classified into the following two types. One is a method in which a continuously running web is brought into contact with a coating rod to transfer and apply a coating solution to the web and to obtain a desired coating amount. This is an integrated application / measurement system that performs measurement together. Another method is to apply an excess coating solution to a web with a pre-coating device such as an extrusion coating device, contact a coating rod with the coating solution, and scrape off the excess of the coating solution. Application that measures the amount of application
This is a separate measurement type.

In any case, a coating film having a desired thickness is formed on a web using a coating rod such as a flat rod, a wire rod, and a grooved rod.

[0005] Regarding the rod coating method, refer to Japanese Patent Application No.
Japanese Patent Application No. 305772 discloses a method which is excellent in coating film surface quality, enables high-speed coating, and can easily carry out product change. A method for improving and eliminating rib streaks is disclosed, and Japanese Patent Application Laid-Open No. 8-48953 discloses that it is not necessary to supply a large amount of excess coating liquid that does not contribute to the actual coating.
In addition, an apparatus that does not cause uneven coating is disclosed.

[0006]

The conventional rod coating method, however, has the drawback that it is not possible to control the thickness of the coating film with high precision, while it is possible to apply a thin layer with simple equipment. In particular, there is a drawback that the film thickness near the edge of the coating film is sharply reduced compared to the regular film thickness in the central portion, and the entire coating film formed on the web cannot be made into a product, There is a problem that the rate of product loss is high.

[0007] Improvements in the rod coating method are also described in Japanese Patent Application Nos. 10-305772 and 10-30.
However, as disclosed in Japanese Patent Application Laid-Open No. 5771 and Japanese Patent Application Laid-Open No. 8-48953, the control of the film thickness near the edge of the coating film is not improved.

The present invention has been made in view of such circumstances, and provides a rod coating method and apparatus in which the film thickness near the edge of the coating film does not become sharply smaller than that at the center.

[0009]

According to the present invention, in order to achieve the above-mentioned object, the present invention relates to a method of transferring a coating solution onto a flexible belt-shaped support which is in contact with a continuously running flexible belt-shaped support by transferring the coating solution to the flexible belt-shaped support. A coating rod for performing measurement together with the coating rod, or a coating rod for measuring the amount of application by contacting a flexible belt-like support on which the coating liquid is excessively applied and scraping off the excess amount of the coating liquid. ,
In the rod coating method of forming a coating film having a desired film thickness on the flexible belt-shaped support by using the non-coated portion of the end portion of the flexible belt-shaped support, The method is characterized in that transfer coating of the coating liquid or scraping of an excessive amount of the coating liquid is performed by the coating rod in a state where the coating liquid is lifted from the coating section.

Further, in order to achieve the above object, the present invention provides a method for simultaneously transferring a coating solution onto a flexible belt-like support which is continuously running and measuring the amount of coating. Using a coating rod to perform the measurement of the amount of coating by contacting the flexible belt-shaped support coated with an excessive amount of the coating solution and scraping off the excess amount of the coating solution. In a rod coating apparatus for forming a coating film having a desired film thickness on a flexible belt-shaped support, when the coating rod is used for transfer coating of a coating liquid or scraping off excess coating liquid, Lifting means for lifting the non-coated portion at the end of the flexible belt-shaped support from the coated portion at the center of the flexible belt-shaped support.

According to the present invention, the coating rod is provided in a state where the uncoated portion at the end of the flexible belt-shaped support is lifted higher than the coating portion where the coating film is formed at the center of the flexible belt-shaped support. The transfer of the coating solution or the scraping of the excess of the coating solution is performed by the following method, so that the film thickness near the edge of the coating film after the measurement becomes sharply thinner than the normal film thickness at the center. It can be suppressed effectively.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the rod coating method and apparatus according to the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is an overall configuration diagram of a rod coating apparatus 10 according to the present invention, in which the present invention is applied to a separate rod coating apparatus for coating and measuring.

The rod coating apparatus 10 mainly comprises an extrusion type precoating apparatus 16 for applying the coating liquid 14 on the web 12 in excess of a desired amount, and a coating apparatus 14 for applying the coating liquid 14 on the web 12 in excess. It is composed of a coating rod device 18 for scraping the excess and a plurality of guide rollers 20, 20, 20 provided along the web transport path.

Extrusion type precoating apparatus 1
Reference numeral 6 denotes a head tip surface of the coating liquid 14 fed into the pocket 22 from the outlet 24A of the slot 24 communicating with the pocket 22 to the web 12 mounted on the guide roller 20 and running at a constant speed in the direction of the arrow. Discharge is continuously performed while pressing 26. Thereby, the coating rod device 18
Immediately before, an excessive coating solution is applied to the lower surface of the web 12. The precoating device 16 is not limited to the extrusion type, and any coating machine that applies a coating solution to the web 12 can be used.

The coating rod device 18 is configured by supporting a column-shaped coating rod 28 disposed in parallel with the width direction of the web 12 on a rod support member 30.
With 0, the running web 12 is brought into contact with the coating rod 28 with a predetermined wrap angle. This allows
An excess amount of the coating solution 14 excessively applied to the web 12 by the precoating device 16 is scraped off by a coating rod 28 and measured to a desired amount of the coating solution. In this case, the coating rod 28 may rotate in the same direction as the traveling direction of the web 12 by contacting the web 12,
It may not be rotated. Further, the coating rod 2
A rotating drive source (not shown) may be connected to the rotating member 8 to rotate in a direction opposite to the running direction of the web 12. Examples of the coating rod 28 used here include a flat coating rod having a flat rod surface, a wire-type coating rod in which a wire is densely wound around the rod, and a circumferential direction of the rod base material surface. For example, a grooved-type coating rod having grooves formed therein may be used. In addition, the coating rod 28
When the excess amount of the coating liquid 14 is scraped off from the web 12,
Since wear of the contact with the rod surface is promoted and inorganic particles such as abrasive agent contained in the coating solution 14, the material of the rod, Vickers hardness (H _v) is 1000 or more, preferably 2000 or more superhard Are preferred. The diameter of the coating rod 28 is often 1 mm to 20 mm, but is not particularly limited.

In the rod coating apparatus 10 of the present invention, when the coating rod 28 is used to scrape off the coating liquid 14 in an excessive amount, the non-coating portion at the end of the web (the same web as the coating liquid is coated). In terms of surface, a lifting means is provided for lifting a portion where the coating liquid is not applied by the precoating device 16 from a coating portion (a portion where the coating liquid is applied by the precoating device 16) at the center of the web. Next, various aspects of the lifting means will be described.

FIG. 2 shows a first embodiment of the lifting means.
The end portion of the coating rod 28 is provided with a step portion 32 having a larger diameter than a central portion 28A of the coating rod 28 (a portion where an excess amount of the coating liquid is scraped off). FIG.
2A shows a case where a step portion 32 is formed at an end of a flat type coating rod 28, and FIG. 2B shows a case where a step portion 32 is formed at an end of a wire 34 portion of the wire type coating rod 28.
Is formed. The step 32 is preferably formed at both ends of the coating rod 28, but may be formed only at one end. The step side surface 32A following the step portion 32 from the center of the coating rod 28 may be formed at a right angle as shown in FIG. 3A, or may be formed in a tapered shape as shown in FIG. It may be formed in a curved shape as shown in FIG.

When the excess amount of the coating liquid 14 is scraped off by the coating rod 28 provided with the lifting means of the first embodiment, as shown in FIG.
The web 12 is transported so that 2A rides on the step 32. Accordingly, when the coating rod 28 is scraped off by the coating rod 28, the non-coating portion 1 at the end of the web is removed.
2A can be lifted higher than the coating portion where the coating film A is formed at the center of the web, so that the film thickness near the edge B of the coating film A measured by the coating rod 28 is the desired thickness at the center of the coating film. Can be effectively suppressed from being rapidly reduced in thickness as compared with the thickness of the film. Hereinafter, a phenomenon that the film thickness near the edge B of the coating film A after the measurement becomes sharply smaller than the desired film thickness is referred to as “edge dripping”. In this case, as shown in FIG.
The thickness of the coating film A after the measurement is defined as h (μm),
Is set to H (μm), the distance (L) from the edge B of the coating film A to the edge 32B of the step 32 is 0.5 mm or more so that 2 ≦ H / h ≦ 50. 30
It is preferable to set the lifting conditions so as to be equal to or less than mm.

FIG. 5 shows a second embodiment of the lifting means.
The liquid material 36 is applied to the non-application portions 12A at both ends of the web so as to swell along the running direction of the web 12. The liquid material 36 may be the same as the coating liquid 14, but when the coating rod 28 scrapes off excess coating liquid 14, the liquid substance 36
Is stretched flat by contact. Therefore, it is necessary that the thickness (H) of the flattened liquid material 36 rises higher than the thickness (D) of the coating film A of the web 12. From this, the coating liquid 14 applied to the web 12
It is preferable that the liquid material 36 has a higher viscosity than that of the liquid material 36.

When the excess of the coating liquid 14 is scraped off by the lifting means of the second embodiment, the non-coated portion 12A of the web 12 is placed on the raised liquid material 36 as shown in FIG. Then, the web 12 is transported. Thus, when the coating rod 14 is scraped off by the coating rod 28, the non-coating portion 12A at the end of the web is lifted higher than the coating portion at the center of the web where the coating film A is formed. Can be effectively suppressed. In this case, when the thickness of the measured coating film A applied to the web 12 is h (μm) and the swell height H (μm) of the liquid material 36 is 2 ≦ H / h ≦ 50. In addition, it is preferable to set the lifting condition so that the distance from the edge B of the coating film A to the edge 36A of the liquid portion 36 is 0.5 mm or more and 30 mm or less.

FIG. 6 shows a third embodiment of the lifting means.
This is a combination of the first embodiment in which the step portion 32 is formed at the end of the coating rod 28 and the second embodiment of the liquid material 36 formed in the non-application portion 12A of the web 12.

When the excess of the coating liquid 14 is scraped off by the lifting means of the third embodiment, the liquid material 3 applied to the non-application portion 12A of the web 12 is removed as shown in FIG.
The web 12 is conveyed so that 6 rides on the step 32 of the coating rod 28. Thereby, the coating rod 28
When the excess amount of the coating liquid 14 is scraped off, the non-coating portion 12A at the end of the web can be lifted more than the coating portion at the center of the web, so that end dripping can be effectively suppressed. . In this case, as in the first and second embodiments, the distance (L) from the edge B of the coating film A to the edge 36A of the liquid material 36 is set so that 2 ≦ H / h ≦ 50.
Is preferably 0.5 mm or more and 30 mm or less, but H is the sum of the height of the step portion 32 and the thickness of the liquid material 36.

FIG. 7 shows a fourth embodiment of the lifting means.
A pair of web support members 38 that support the non-coating portions 12A at both ends of the web 12 at positions higher than the coating rod 28 on the upstream and downstream sides of the web 12 with the coating rod 28 interposed therebetween, respectively. 38.

When the excess of the coating solution 14 is scraped off by the lifting means of the fourth embodiment, as shown in FIG. 7B, the non-coating portions 12A at both ends of the web are supported by a pair of web supports. The web 12 is transported so as to ride on the member 38. Thus, when the excess amount of the coating liquid 14 is scraped off by the coating rod 28, the non-
Since A can be lifted more than the application portion at the center of the web, it is possible to effectively suppress the end sag. In this case, the pair of web support members 38 are connected to the coating rod 2.
8 may be arranged on either one of the upstream side and the downstream side in the running direction of the web 12 with the sandwiched portion 8 interposed therebetween.

FIG. 8 is an overall structural view of a rod coating apparatus 40 according to the present invention.
This is a case where the present invention is applied to a rod coating device provided with a.

As shown in FIG. 8, a column-shaped coating rod 42 is arranged in the width direction of the running web 12 in contact with the running web 12. The coating rod 42 is rotatable in the direction in which the web 12 runs, and is supported on a rod support member 44 so as not to hinder rotation.
The application liquid 14 supplied to the application liquid supply path 48 formed by the rod support member 44 and the weir member 46 forms a liquid pool 50 at a contact portion between the web 12 and the coating rod 42, The coating liquid 14 is transferred and applied to the web 12 by the coating rod 42 rotating via the liquid pool 50.
The coating rod 42 has a groove formed on the peripheral surface of the rod up to near both ends of the rod (wire type rod).
The amount of the coating liquid is substantially determined by the size of the groove. At both ends of the coating rod 42, step portions 52 having a diameter larger than that of the central portion of the coating rod are formed as lifting means. This step 52 is the same as that described with reference to FIGS.

When transfer coating of the coating liquid 14 and measurement of a desired coating amount are performed simultaneously by the coating rod 42 having the step 52 formed thereon, as shown in FIG.
The web 12 is transported so that the second non-coating portion 12A rides on the step 52 of the coating rod 42. This allows
The transfer coating of the coating solution 14 and the measurement of the desired amount of the coating solution can be performed together, and the non-coating portion 12
A can be lifted more than the coating portion where the coating film A is formed at the center of the web, so that the sag can be effectively suppressed. Also in this case, when the thickness of the measured coating film A is h (μm) and the step of the step portion 52 is H (μm), 2 ≦ H / h ≦ 50 and the coating film A It is preferable to set the lifting condition so that the distance (L) from the edge B of the stepped portion 52 to the edge (not shown) of the step portion 52 is 0.5 mm or more and 30 mm or less.

As a lifting means in the rod coating apparatus 40 provided with the coating rod 42 for simultaneously performing the transfer coating of the coating liquid 14 and the measurement of a desired amount of the coating liquid, a step 52 is used.
Although only the example of FIG. 6 is shown, the liquid material 36 shown in FIG.
As shown in the above, the combination of the step portion 52 and the liquid material 36,
Further, it goes without saying that the web support member 38 shown in FIG. 7 may be used.

As described above, according to the present invention, the coating liquid is applied by the coating rod 42 while the non-coated portion 12A at the end of the web is raised above the coated portion where the coating film A is formed at the center of the web. Since the transfer coating of 14 or the scraping off of the excess amount of the coating liquid 14 is performed, edge dripping can be effectively suppressed.

Therefore, the coating film A applied to the web 12
Can be made into a product, so that productivity can be improved.

The web 12 used in the present invention includes:
Generally, the width is 0.3 to 1 m and the length is 45 to 1000
0 m, polyethylene terephthalate (PET) having a thickness of 2 to 200 μm, polyethylene-2,6-naphthalate,
Cellulose films such as cellulose diacetate, cellulose triacetate, cellulose acetate propionate, polyvinyl chloride, polyvinylidene chloride, polycarbonate, polyimide, polyamide, etc., paper, polyethylene, polypropylene, ethylene butene copolymer, etc. Α-polyolefin coated or laminated paper, aluminum, copper, a flexible band made of metal foil such as tin or the like, or a band formed by forming a processed layer on the surface of the band. .

The coating liquid 14 used in the present invention includes:
Not only a non-Newtonian fluid such as a coating solution for a magnetic tape, but also a Newtonian fluid in which a relatively low-viscosity gelatin solution of a photographic photosensitive layer is used as a binder.

[0034]

EXAMPLE A practical test of the present invention was carried out using a rod coating apparatus equipped with a coating rod for scraping off an excess of the coating liquid applied to the web of FIG. 1 with a coating rod.

As the lifting means, a rod having the steps formed at both ends of the coating rod described with reference to FIG. 4 was used.

[0036] The coating liquid used was one in which each component having the composition shown in Table 1 was thoroughly mixed and dispersed in a ball mill, and then 30 parts by weight of an epoxy resin (epoxy equivalent: 500) was uniformly mixed and dispersed. did.

[0037]

[Table 1]

The end sag when the application conditions including the application speed, the application amount h after the measurement, the type of coating rod, the thickness of the web, the step height H of the step portion, and the distance between the edges are changed. Was measured.

The edge sag indicates the rate of change (%) of the film thickness at the edge of the coating film with respect to the desired thickness of the coating film after measurement, and changes in a direction in which the thickness of the edge becomes thinner. Say the case. If the amount of edge sag is within -10%, the entire coating film can be made into a product. here,
FIG. 9A shows a state in which the edge sag exceeds -10% and the edge sagging with respect to the desired thickness (D) of the coating film is not sufficiently improved. On the other hand, FIG. 9B shows that the uncoated portion at the end of the web is lifted too much higher than the coated portion at the center of the web, so that the film thickness at the edge of the coated film is larger than the desired thickness (D). It is in a state where it is.

Table 2 shows test results showing the relationship between the coating conditions and the amount of edge sag.

In Table 2, Examples 1 to 13 show that the non-coated portion at the end of the web of the present invention was lifted higher than the coated portion at the center of the web, and the lifting conditions were as follows. When the thickness is h (μm) and the step at the step is H (μm), the distance (L) from the edge of the coating film to the edge of the step is such that 2 ≦ H / h ≦ 50. Is set to 0.5 mm or more and 30 mm or less.

In Comparative Example 1, a conventional coating rod having no step was used. Comparative Examples 2 to 5
The non-coated portion of the web is lifted by a coating rod having a stepped portion, which is the same as that of the embodiment.
≦ H / h ≦ 50 and at least one of 0.5 mm or more and 30 mm or less does not satisfy the condition.

In Table 2, F indicates a flat rod, C indicates a wire rod, C indicates a wire rod, and a step height H of 0 indicates a conventional coating rod having no step, and a distance between edges. Means from the edge of the coating film to the edge of the step.

[0044]

[Table 2]

From the results shown in Table 2, the end sag amount of Comparative Example 1 using the conventional coating rod having no step was -30%.
And Examples 1 to 13 and Comparative Examples 2 having a step portion
In No. 4, the edge sag was the largest. From this,
It has been confirmed that by raising the non-coated portion at the end of the web higher than the coated portion at the center of the web, it acts in a direction to reduce the amount of end sag as compared with a case where the web is not lifted. When the distance between edges in Comparative Example 5 was eliminated, the edge of the coating film was disturbed and stable coating could not be performed, so that the amount of edge sag could not be measured.

Embodiments 1 to 5 which also satisfy the lifting conditions
13 and Comparative Examples 2 to 4, which do not satisfy the lifting conditions, all the sagging amounts of Examples 1 to 13 were within 10% of the soil, and the entire coating film could be commercialized. .

On the other hand, the sagging amount of Comparative Examples 2 to 4 which did not satisfy the lifting condition was -20 to +11, which was out of the range of 10% for soil.

From this, the non-coated portion at the end of the web is lifted higher than the coated portion at the center of the web, and the thickness of the coated film after measurement is h (μ) as a lifting condition.
m), and when the height of the step is H (μm), 2
≦ H / h ≦ 50, and the distance (L) from the edge of the coating film to the edge of the step portion is 0.5 mm or more, 3
It is possible to set the lifting condition so as to be 0 mm or less,
It can be said that it is preferable for effectively reducing the amount of edge sag.

[0049]

As described above, according to the rod coating method and apparatus of the present invention, it is possible to prevent the film thickness near the edge of the coating film from becoming sharply thinner or thicker than the central portion. Therefore, the entire coating film can be made into a product.

Thus, the product loss can be greatly reduced, and the productivity can be improved.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a rod coating apparatus of the present invention of a separate coating and measuring type.

2A is a perspective view of a flat type coating rod having a step portion, and FIG. 2B is a perspective view of a wire type coating rod having a step portion.

FIG. 3 is an explanatory view illustrating a shape of a step side surface of a coating rod having a step portion.

FIG. 4 is an explanatory diagram for explaining the operation when the lifting means is constituted by a step portion;

FIG. 5 is an explanatory view for explaining the operation when the lifting means is made of a liquid material.

FIG. 6 is an explanatory view for explaining the operation when the lifting means is constituted by a combination of a step portion and a liquid material.

FIG. 7 is an explanatory view for explaining the operation when the lifting means is constituted by a web support member.

FIG. 8 is an overall configuration diagram of a rod coating apparatus of the present invention, which is an integrated coating and measuring type.

FIG. 9 is an explanatory view of an end sag in the embodiment implemented by the rod application device of the present invention of a separate application / measurement type.

[Explanation of symbols]

Reference Signs List 10: coating / measuring separate rod coating device, 12: web, 14: coating liquid, 16: precoating device, 18: coating rod device, 20: guide roller, 22: pocket,
Reference numeral 24: Slot, 26: Head tip surface, 28: Coating rod, 30: Rod support member, 32: Step portion, 32A ...
Side surface of step, 34: wire, 36: liquid material, 38: web support member, 40: rod coating device of integral coating and measuring type, 42: coating rod, 50: pool of coating liquid, 52 ...
Step, A: coating film

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Tokuo Shibata 1-2-1 Ogimachi, Odawara-shi, Kanagawa F-film F-term (reference) 4D075 AC03 AC53 AC84 AC92 DA04 DC27 4F040 AA22 AB04 AC01 BA23 CB19 CB35 4F042 AA22 DD09 DD41 DD45

Claims (7)

[Claims] 1. A coating rod or a coating liquid for contacting a continuously running flexible strip-shaped support and transferring the coating solution to the flexible strip-shaped support and measuring the applied amount together. A coating rod for measuring the amount of application by scraping off the excess amount of the coating solution in contact with the excessively coated flexible belt-like support,
In a rod coating method of forming a coating film having a desired thickness on the flexible belt-shaped support by using a non-coated portion of the end portion of the flexible belt-shaped support, A rod coating method, wherein transfer coating of the coating liquid or scraping of an excessive amount of the coating liquid is performed by the coating rod in a state where the coating liquid is lifted from the coating section. 2. A coating rod or a coating liquid for contacting a continuously running flexible belt-shaped support and transferring the coating solution to the flexible strip-shaped support and measuring a coating amount together. A desired film thickness is applied to the flexible belt-shaped support by using a coating rod for measuring the amount of application by scraping off the excess amount of the coating solution in contact with the excessively coated flexible belt-shaped support. In the rod coating apparatus for forming a coating film, when the transfer rod of the coating solution or scraping off the excess of the coating solution with the coating rod, the non-coated portion of the end portion of the flexible belt-shaped support body, A rod coating apparatus, comprising lifting means for lifting the flexible belt-shaped support above the coating portion at the center. 3. A rod coating apparatus according to claim 2, wherein said lifting means is a step formed at an end of said coating rod and having a larger diameter than a center of said coating rod. 4. When the thickness of the coating film after measurement applied to the flexible belt-shaped support is h (μm) and the step of the step portion is H (μm), 2 ≦ H / h ≦ The rod according to claim 3, wherein the non-coated portion is lifted so as to be 50 and a distance from an edge of the coating film to an edge of the step portion is 0.5 mm or more and 30 mm or less. Coating device. 5. The lifting means is a liquid material applied to the non-applied portion of the flexible strip support so as to swell along the running direction of the flexible strip support. The rod coating device according to claim 2, wherein 6. When the thickness of the measured coating film applied to the flexible belt-shaped support is h (μm) and the height of the liquid material is H (μm), 2 ≦ H / The non-coating portion is lifted so that h ≦ 50 and a distance from an edge of the coating film to an edge of the liquid portion is 0.5 mm or more and 30 mm or less. Rod coating equipment. 7. The lifting means is provided on at least one of an upstream side and a downstream side of a traveling direction of the flexible strip-shaped support with the coating rod interposed therebetween, and is provided at a position lower than the coating rod. 3. The rod coating device according to claim 2, wherein the support member supports both ends of the flexible band-shaped support at a high position.