Coating processes – Nonuniform coating – Metal – glass – or ceramic base
Patent
1994-09-09
1996-06-04
Beck, Shrive
Coating processes
Nonuniform coating
Metal, glass, or ceramic base
4271261, 427428, 118253, 118249, 118261, B05D 512
Patent
active
055231225
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a process and an apparatus for coating a slurry coating material onto a continuous base sheet at a given thickness, and particularly to a process and an apparatus for intermittently coating a slurry coating material to alternately form coated and uncoated areas, of predetermined lengths on a base sheet.
In mass production of, for example, a spiral electrode type lithium battery, the following intermittent coating technique is employed. A band-shaped hoop material of a copper or an aluminum foil serving as a current collector of a battery is used as a base sheet, and a slurry mixture containing an electrode active substance as a main component is used as a coating material. The coating material is applied to the base sheet, for example, over an area having a length of 30 cm at a given thickness in such a manner that the coating material is not applied at all to a subsequent area having a length of 5 cm, thereby alternately forming a coated area having a predetermined length and an uncoated area having a predetermined length on the continuous base sheet.
The most typical process used to carry out such an intermittent coating operation employs a coating device referred to as a reverse roll coater as shown in FIG. 7.
Referring to FIG. 7, a coating roll 1 (hereinafter referred to as a C-roll) is rotated at a predetermined speed in a direction indicated by an arrow a. A backing roll 2 (hereinafter referred to as a B-roll) is in contact with the C-roll 1 with a base sheet 3 interposed therebetween and is rotated in a direction opposite from the direction of rotation of the C-roll 1 (i.e., in a direction indicated by an arrow h). The base sheet 3 is allowed to travel in a direction indicated by an arrow c along the B-roll 2 and to pass between the C-roll 1 and the B-roll 2.
An adjuster referred to as a doctor roll 4 (hereinafter referred to as a D-roll) is fixedly (i.e., non-rotatably) mounted above the C-roll 1 and is spaced a predetermined distance therefrom. A coating material 6 accumulated in a hopper 5 is deposited onto a peripheral surface of the C-roll 1 to pass through a region of a minimum distance between the C-roll 1 and the D-roll 4, whereby the amount of coating material 6 applied to the base sheet 3 is controlled to a value (thickness) corresponding to such distance.
A coating layer 6a controlled to the predetermined thickness by the distance between the C-roll 1 and the D-roll 4 is transferred onto the base sheet 3 when the base sheet 3 is passed between the B-roll 2 and the C-roll 1. In this manner, a coating layer 6b having a controlled constant thickness is continuously applied onto the base sheet 3.
In order to intermittently form uncoated areas, there is mounted an operating mechanism for moving the B-roll 2 in parallel in a direction perpendicular to a rotational axis thereof. Thus, the B-roll 2 is displaced in a direction indicated by an arrow d at every given time interval, until it is sufficiently spaced apart from the C-roll 1 so that the coating layer 6a is not transferred from the C-roll 1 to the base sheet 3. After a lapse of a predetermined time, the B-roll 2 is displaced in a direction indicated by an arrow e back to its original position, and the coating layer 6a on the C-roll 1 again is transferred to the base sheet 3. By repeating such operations, the above-described intermittent coating can be achieved.
However, the above prior art intermittent coating process may suffer from a problem that it is impossible to control the thickness of the coating layer 6b in the coated area to a constant value with high accuracy. This is due to the movement of the B-roll 2 during switching from a coating position to an uncoating position. The amount of coating material 6 applied to the base sheet 3 is controlled basically by the distance between the C-roll 1 and the D-roll 4 and the rotational speeds of the C-roll 1 and the B-roll 2. However, the coating material 6 is applied to the base sheet 3 in a manner that the coating layer 6b is
REFERENCES:
patent: 4339481 (1982-07-01), Beekhuis
patent: 4485132 (1984-11-01), Furuzono et al.
patent: 4603060 (1986-07-01), Mitsuda et al.
Harada Yoshiro
Hironaka Kazuhiko
Kobara Hiroshi
Yamamoto Kohei
Bareford Katherine A.
Beck Shrive
Fuji Electrochemical Co. Ltd.
Hirano Tecseed Co., Ltd.
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