Coating processes – With post-treatment of coating or coating material – Solid treating member or material contacts coating
Reexamination Certificate
2002-06-24
2004-04-27
Bareford, Katherine A. (Department: 1762)
Coating processes
With post-treatment of coating or coating material
Solid treating member or material contacts coating
C427S402000, C118S410000, C118S411000
Reexamination Certificate
active
06726958
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a coating method, as well as a coating apparatus, which applies a coating liquid onto a continuously moving belt-shaped support (web-shaped support), and more specifically to a coating apparatus as well as a coating method which minimizes fluctuation of lateral coating thickness.
Conventionally known as methods to apply a coating liquid onto a continuously moving belt-shaped support have been a dip coating method, a blade coating method, an air knife coating method, a wire bar coating method, a gravure coating method, a reverse coating method, a reverse roller coating method, an extrusion coating method, a slide coating method, and a curtain coating method. Further, in these coating methods, the coating has been attentively carried out while paying special attention to the size as well as the accuracy of coating apparatuses so as to obtain a uniform dried lateral thickness of the coating.
Incidentally, the coating apparatus, as described in the present invention, refers to a coater and more specifically refers to a coater which comprises a pocket which uniformly supplies a supplied coating liquid in the lateral coating direction and a slit which uniformly extrudes the coating liquid which has been supplied to said pocket. Listed as such coaters are, for example, an extrusion coater, a slide coater and a curtain coater.
Of these coating methods, in the case of the extrusion coating method, two methods have been known. One, namely, is a method in which coating is carried out while a belt-shaped support, at the initiation of coating, is supported by a back roller, and the other is one in which coating is carried out while said belt-shaped support is not supported.
In regard to the extrusion coating method in which coating is carried out while a belt-shaped support, at the initiation of coating, is supported by a back roller, many patents have been applied for coating systems as well as coating apparatuses, such as Japanese Patent Publication Open to Public Inspection Nos. 56-95363 and 50-142643 which disclose single layer coating methods, as well as Japanese Patent Publication Open to Public Inspection Nos. 45-12390 and 46-236 which disclose multilayer coating systems. In these coating methods, coating is carried out in such a manner that the gap between the coater and the belt-shaped support supported by the back roller is commonly maintained to be less than or equal to 1 mm. Further, atmospheric pressure may be reduced upstream as disclosed in U.S. Pat. No. 2,681,294.
When coating is carried out employing a belt-shaped support, as a method to minimize fluctuation of lateral coating thickness, it has heretofore been carried out to mechanically adjust the lateral gap between the coater and the belt-shaped support. Further, recently, Japanese Patent Publication Open to Public Inspection No. 8-215631 discloses a technique in which a mechanism, which adjusts the gap between the coater and the belt-shaped support, is allowed to move in the lateral direction so that said gap can be adjusted at an optional position.
In regard to the extrusion coating method in which coating is carried out while the belt-shaped support, at the initiation of coating, is not supported by the back roller, many patents have been applied for coating systems as well as coating apparatuses, such as Japanese Patent Publication Open to Public Inspection Nos. 50-138036, 55-165172, and 1-288364 which disclose single layer coating methods, as well as Japanese Patent Publication Open to Public Inspection Nos. 2-251265, 2-258862, and 5-192627 which disclose multilayer coating systems.
In these coating methods, coating is carried out in such manner that the coating liquid outlet of the coater is brought into direct contact with a moving belt-shaped support in the free span between support rollers, which do not support said moving support.
In said methods, fluctuation of the lateral coating thickness on said belt-shaped support has been minimized as follows. Heretofore, as disclosed in Japanese Patent Publication Open to Public Inspection No. 2-207866, the degree of the lateral right angle of the edge of the coating liquid outlet of the coater is enhanced. Further, as disclosed in Japanese Patent Publication Open to Public Inspection Nos. 9-141173 and 11-60006, are methods recently employed in which a pressing member, which presses a belt-shaped support in the specified direction, is installed near the extrusion coater so that even though said belt-shaped support exhibits some distortion in the lateral direction, fluctuation of coating thickness as well as non-coating is minimized.
In the prior art, no disclosure has been made for how a coater itself is designed so as to match products to be coated. Further, the desired accuracy to coat said products has also not been disclosed.
As a result, when a prepared coater results in an insufficient uniformity of lateral coating thickness upon coating a coating liquid, coating is carried out while making trial and error operations such as mechanical adjustment of the gap, as well as a survey for coating conditions so that the desired uniform thickness is achieved. However, a large and expensive equipment is required to make it possible to perform such operations. In addition, it requires difficult adjustment operations and it is difficult to accurately adjust said gap to the desired spacing. Accordingly, when coating is carried out employing a coater comprising a pocket as well as a slit, it is demanded to develop a coating apparatus as well as a coating method which minimizes fluctuation in lateral coating thickness as well as satisfies coating conditions while being independent of trial and error operations, such as mechanical adjustment of the slit distance as well as alteration of coating conditions.
SUMMARY OF THE INVENTION
From the viewpoint of the foregoing, the present invention was achieved.
An object of the present invention is to provide an optimal coating apparatus as well as an optimal coating method which matches the physical properties of a coating fluid as well as coating conditions in order to minimize fluctuation in the lateral coating thickness in coatings which employ a coater comprising a pocket as well as a slit.
Embodiments to achieve the aforesaid object of the present invention will now be described.
1. In a coating apparatus, comprising at least one set of a slit and a pocket, which applies at least one layer comprising a coating liquid having a viscosity of &mgr; (in Pa·s) onto a belt-shaped support (web-shaped support) at a coating rate (coating speed) of u (in mm/s) so as to obtain a pre-drying coating thickness (wet coating layer thickness) of hw (in mm), a coating apparatus wherein either slit length Ls (in mm) or slit gap h (in mm) is set so as to satisfy the relationship of:
1×10
4
<12×&mgr;×
Ls×hw×u/h
3
≦4×10
5
.
2. In a coating method, employing a coating apparatus, provided with at least one set of a slit having a length of Ls (in mm) and a slit having a gap of h (in mm), which applies at least one layer onto a belt-shaped support at a coating rate of u (in mm/s), a coating method wherein coating liquid viscosity &mgr; (in Pa·s) and pre-drying coating thickness hw (in mm) are adjusted to satisfy the relationship of:
1×10
4
<12×&mgr;×
Ls×hw×u/h
3
≦4×10
5
.
3. In a coating method, employing a coating apparatus, provided with at least one set of a slit having a length of Ls (in mm) and a slit having a gap of h (in mm), which applies at least one layer comprised of a coating liquid of a viscosity of &mgr; (in Pa·s) onto a belt-shaped support so as to obtain a pre-drying coating thickness of hw (in mm), a coating method wherein coating is carried out by adjusting the coating rate to u (in mm/s) so as to satisfy the relationship of:
1×10
4
<12×&mgr;×
Ls×hw×u/h
3
≦4×10
5
.
4. In a coating apparatus, which is provided with at least one set of a slit and a pocket, an
Bareford Katherine A.
Konica Corporation
Muserlian Lucas and Mercanti
LandOfFree
Coating method with select parameters does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Coating method with select parameters, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Coating method with select parameters will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3250887