Coating processes – With post-treatment of coating or coating material – Solid treating member or material contacts coating
Reexamination Certificate
2002-09-12
2004-11-09
Bareford, Katherine A. (Department: 1762)
Coating processes
With post-treatment of coating or coating material
Solid treating member or material contacts coating
C427S428010, C118S118000, C118S119000, C118S244000, C118S258000, C118S259000
Reexamination Certificate
active
06815008
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a bar coating apparatus and a bar coating method. More specifically, the invention relates to the bar coating apparatus and the bar coating method that are capable of applying a desired amount of coating solution to an object to be coated.
2. Description of the Related Art
In order to apply a coating solution to an object to be coated such as a metal plate and to remove excessive coating solution from the object to be coated (so-called measurement), a bar coating apparatus
102
as shown in
FIG. 23
is conventionally used.
The bar coating apparatus
102
has a columnar coating bar
106
, which is arranged so as to contact with a coating surface (lower surface) of a metal plate
104
in a direction perpendicular to a conveyance direction of the metal plate
104
(direction of arrow F
1
), which is conveyed at a constant conveyance speed. The coating bar
106
rotates due to friction with the metal plate
104
at a peripheral speed equal to the conveyance speed of the metal plate
104
. A coating solution
108
is raised by the rotation of the coating bar
106
, and a bead
110
is arranged between a weir member
112
and the metal plate
104
. Namely, the coating solution in the bead
110
is applied to the metal plate
104
and any excess coating solution is removed (measured) from the metal plate
104
.
Plates of various thicknesses are used for the metal plate
104
as an object to be coated. However, with changes in the thickness of the metal plate
104
, a clearance between the metal plate
104
and the weir member
112
also changes. As a result, the bead
110
becomes unstable, which causes difficulty in obtaining uniformly coated surface quality.
In addition, the metal plate
104
occasionally flaps vertically and ripples due to conveyance. For this reason, the contacted state between the metal plate
104
and the coating bar
106
cannot be maintained constantly, and the bead
110
occasionally becomes unstable. Particularly recently, the conveyance speed of the metal plate
104
tends to be increased, and thus the possibility of the bead
110
not maintaining stability increases due to the higher speed. When the bead
110
becomes unstable, for example, it becomes difficult to obtain a uniformly coated surface quality because a coating streak is caused by the disturbance of the bead
110
.
Further, the instability of the bead
110
due to the increased conveyance speed of the metal plate
104
causes the generation of so-called entrained air (air that is trapped inside the coating solution at the time of coating), which can decrease the coated surface quality. When the clearance between the weir member
112
and the object to be coated (metal plate
104
) is large, the effect of the entrained air upon the coating solution is particularly noticeable. Hence, the bead
110
has a tendency to become unstable, and that in turn causes difficulty in obtaining uniform coated surface quality.
Furthermore, factors such as increased conveyance speed of the plate, increased viscosity of the coating solution, and varying conditions at the time of coating can hinder maintenance of stability in the bead
110
. Disturbance of the bead results in problems such as difficulty in obtaining uniform coated surface quality due to coating streaks and coating breakage.
SUMMARY OF THE INVENTION
In view of the above facts, an object of the present invention is to provide a bar coating apparatus and a bar coating method, which are capable of obtaining uniformly coated surface qualities by corresponding to the various thickness of the objects to be coated.
In addition, it is another object of the invention to provide a bar coating apparatus and a bar coating method which are capable of obtaining uniformly coated surface quality even if a conveyance speed of an object to be coated is increased or a viscosity of a coating solution is increased.
A first aspect of the invention is a bar coating apparatus comprising: a coating bar for contacting an object to be coated, which object is conveyed in a constant direction, so as to apply a coating solution to and remove excess coating solution from the object to be coated; a weir member for forming a bead of the coating solution between the object to be coated and the coating bar, the weir member being disposed upstream of the coating bar in a direction in which the object to be coated is conveyed; a pressing member for pressing the object to be coated from a side thereof opposite from the coating bar, the pressing member being disposed near the coating bar; and a moving device for moving the pressing member in a thickness direction of the object to be coated.
Further, in the first aspect, the pressing member is a pressing roll that is rotatingly driven by friction with the object to be coated.
Furthermore, in the first aspect, the bar coating apparatus further comprises a rotational drive for rotating the coating bar at a peripheral speed that differs from a peripheral speed corresponding to the speed at which the object to be coated is conveyed.
A second aspect of the invention is a bar coating method of bringing a coating bar into contact with an object to be coated, which object is conveyed in a constant direction, so as to apply a coating solution to and remove excess coating solution from the object to be coated, comprising the steps of: supplying the object to be coated; pressing, with a pressing member disposed near the coating bar, the object to be coated from a side thereof opposite from the coating bar; and moving, in correspondence to a coating state, the pressing member in a thickness direction of the object to be coated.
Further, in the second aspect of the invention, the coating bar is rotated at a peripheral speed that differs from a peripheral speed corresponding to the speed at which the object to be coated is conveyed.
In the bar coating apparatus according to the first aspect, the coating bar is brought into contact with the object to be coated, which is conveyed, and the coating solution is applied to the object to be coated. The object to be coated is pressed by the pressing member from the opposite side of the coating bar in the vicinity of the coating bar. The pressing member can be moved in a thickness direction of the object to be coated by the moving apparatus. Therefore, even if the objects to be coated have various thicknesses, the pressing member is moved, and the clearance between the object to be coated and the weir plate is adjusted, so that the bead of the coating solution formed among the weir member, the coating bar and the object to be coated can be stabilized. For this reason, a coated surface quality of the object to be coated is also stabilized, and even if the object to be coated has various thicknesses, the uniform coated surface quality can be obtained.
In addition, a member that merely contacts and presses the object to be coated may be used as the pressing member. However, when the pressing member is a pressing roll, which is driven to rotate by friction with the object to be coated, the object to be coated can be prevented from being rubbed and damaged by the pressing roll.
Further, when the coating bar is not rotated by the friction with the object to be coated, but is actively rotated by the rotation drive at a peripheral speed different from a peripheral speed corresponding to the conveyance speed of the object to be coated, the bead formed among the weir plate, the coating bar and the object to be coated can be stabilized. Therefore, for example, even in the case where the conveyance speed of the object to be coated is increased and the viscosity of the coating solution is increased, the uniform coated surface quality can be obtained.
In the bar coating method according to the second aspect, the coating bar is brought into contact with the object to be coated, which is conveyed, and the coating solution is transferred and applied to the object to be coated. The object to be coated is pressed from the opposite side of th
Ichikawa Kazuki
Kaneko Nobuyoshi
Nishino Go
Bareford Katherine A.
Fuji Photo Film Co. , Ltd.
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