Coating apparatus – Projection or spray type – Flexible web or strand work
Reexamination Certificate
1998-02-13
2001-04-10
Edwards, Laura (Department: 1734)
Coating apparatus
Projection or spray type
Flexible web or strand work
C118S407000, C118S410000, C118S419000
Reexamination Certificate
active
06214114
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a coating method and a coating apparatus, and in particular, to a coating method and a coating apparatus both employing a coater which coats a coating liquid extruded toward the surface of an object to be coated in movement on the surface of the object to be coated to be in constant thickness on a high speed thin layer coating basis. The object to be coated may also be called a support hereinafter.
Various methods to coat a coating liquid on the surface of a flexible support have been studied to be put in practice so far. Among these various coating methods, a coating method by means of a coater of an extrusion type wherein a coating liquid extruded continuously toward the surface of a moving support is coated on the surface of the support to be in constant thickness on a high speed thin layer coating basis is superior to other coating methods of a roll type such as a reverse roll coating, a kiss-roll coating and a gravure-roll coating, for example, on the various points of uniformity of coating, thin layer coating and a range of coating speed available. The coating method by means of a coater of an extrusion type makes a simultaneous multi-layer coating through the so-called wet on wet coating to be possible, and it is effective in terms of cost and performance for the application to manufacture of recent coated products with high value added.
As a conventional coater of an extrusion type, Japanese Tokkaishos 48-98803 and 61-111168, for example, disclose a manufacturing method for magnetic recording media through wet on wet simultaneous multi-layer coating wherein coating liquids superposed in advance are coated on the support which is held on a back roll and is running continuously.
Further, there has been devised a method as that disclosed in Japanese Tokkaisho 62-124631 wherein an upper layer is coated on a support while a lower layer is still wet, without the support of a back roll, by using a coater of a single layer extrusion type, and has been devised a coater head provided with slits from which two coating liquids are extruded as that disclosed in Japanese Tokkaisho 63-88080 and Japanese Tokkaihei 2-251265.
In addition, there has been devised a method as that disclosed in Japanese Tokkaihei 1-203075 and Japanese Tokkaihei 6-254466 wherein a diameter of a support roll positioned directly before or just behind an extrusion type coater is changed to correct a wrinkle caused by the slack in the lateral direction of a support, and a method as that disclosed in Japanese Tokkaihei 1-224071 wherein a means to pressurize a fluid from the back side of a support is provided for the purpose of uniformalizing a wrinkle caused by the slack portion.
It has also been devised a method as that disclosed in WO 92/22418 wherein a pocket portion and a slit portion of an extrusion type coater are changed in terms of shape in the lateral direction for the purpose of uniformalizing the coating liquid flow rate in the lateral direction.
It has further been devised an apparatus as that disclosed in Japanese Tokkaisho 63-20070 wherein there is used an extrusion type coater coating a high viscosity liquid while holding a support with a back roll in which a dimension of a slit is gradually reduced as it approaches a nozzle for a coating liquid, and thereby a pressure loss is reduced to make the coating at high viscosity possible.
However, these methods and apparatuses in prior art have problems that a wrinkle caused by the slack of a support affects, coating streaks are caused by dust in the circumstance and by flocculated substances in a coating liquid, and high speed coating is impossible. In particular, there have not existed an apparatus and a method which make it possible to coat, on a thin wet layer basis, a coating liquid at high speed without being affected by a wrinkle caused by the slack of a support and without creating coating streaks.
SUMMARY OF THE INVENTION
An object of the invention is to provide a coating apparatus capable of coating at high speed without being affected by a wrinkle caused by the slack of a support and without creating coating streaks.
The object stated above can be attained by either one of the following structures (1)-(8).
(1) A coating apparatus having therein the following structures such as a conveyance means to convey an object to be coated and a coater to coat the coating liquid by jetting the coating liquid from a slit in a film shape and by causing the coating liquid to collide with the object to be coated, wherein the coater is not in contact with the object to be coated, and a clearance of a slit exit d (m) of the coater satisfies the relation of 0<d≦5×10
−5
(m), and the slit exit clearance of the coater is smaller than a clearance of a slit inlet through which the coating liquid is injected, and side surfaces which face each other and are in parallel with each other are provided at the slit exit.
(2) The coating apparatus according to Structure (1) above wherein coating speed U (m/s), coated layer wet thickness hw (m) and the clearance of slit exit d (m) are determined so that dimensionless number M expressed by the following expression may satisfy the following relation
M=(&rgr;·U·hw
2
)/(&mgr;·d)>0.2
when viscosity of the coating liquid is represented by &mgr; (Pa·s) and density of the coating liquid is represented by &rgr; (kg/m
3
).
(3) The coating apparatus according to Structure (1) above wherein a clearance between the slit exit and the object to be coated is at least 2.5 times the coated layer wet thickness or more.
(4) The coating apparatus according to Structure (1) above wherein the coating liquid jetted in a shape of a film forms a cross-link portion in a film shape between the coater and the object to be coated.
(5) The coating apparatus according to Structure (1) above wherein slit side surfaces on the side of the slit exit are formed by the member whose Vickers hardness is not less than 280.
(6) A coater to coat a coating liquid wherein the coating liquid is jetted in a shape of a film from a slit to collide with the object to be coated, wherein clearance d (m) on the side of a slit exit of the coater satisfies the relation of 0<d≦5×10
−5
(m), and the slit exit clearance of the coater is smaller than a clearance of a slit inlet through which the coating liquid is injected, and slit side surfaces which face each other and are in parallel with each other are provided at the slit exit.
(7) The coater according to Structure (6) wherein the slit side surfaces on the side of the slit exit is formed by the member whose Vickers hardness is not less than 280.
(8) The coater according to Structure (6) wherein the slit side surfaces which face each other to be in parallel on the side of the slit exit are formed by the member whose Vickers hardness is not less than 280.
REFERENCES:
patent: 4416214 (1983-11-01), Tanaka et al.
patent: 4854262 (1989-08-01), Chino et al.
patent: 5206056 (1993-04-01), Shibata et al.
patent: 5226963 (1993-07-01), Shibata et al.
patent: 5536313 (1996-07-01), Watanabe et al.
patent: 5700325 (1997-12-01), Watanabe
patent: 0 542 635 A1 (1993-05-01), None
patent: 0 557 769 A1 (1993-09-01), None
patent: 0 678 341 A2 (1995-10-01), None
patent: 0 744 221 A2 (1996-11-01), None
patent: 48-98803 (1973-12-01), None
patent: 61-111168 (1986-05-01), None
patent: 62-124631 (1987-06-01), None
patent: 63-20070 (1988-01-01), None
patent: 63-88080 (1988-04-01), None
patent: 1-203075 (1989-08-01), None
patent: 1-224071 (1989-09-01), None
patent: 2-251265 (1990-10-01), None
patent: 6-254466 (1994-09-01), None
patent: 6-508571 (1994-09-01), None
English language Abstract only.
Aizawa Hiroyuki
Kawabe Shigetoshi
Tobisawa Seiichi
Edwards Laura
Frishauf, Holtz Goodman, Langer & Chick, P.C.
Konica Corporation
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