Coating processes – Nonuniform coating – Metal – glass – or ceramic base
Reexamination Certificate
1998-09-04
2002-09-24
Lamb, Brenda A. (Department: 1734)
Coating processes
Nonuniform coating
Metal, glass, or ceramic base
C427S256000, C427S210000, C118S669000, C118S410000, C118S684000
Reexamination Certificate
active
06455105
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to an intermittent coating system and an intermittent coating method for coating a surface of a substrate with a coating agent in an intermittent manner along a conveyance direction of the substrate.
2. Description of Relevant Art
FIG. 1
illustrates a conventional intermittent coating system C
1
. The coating system C
1
is for intermittently coating an electrode substrate
3
of a lithium ion secondary battery, with of an electrode composite material as a coating agent
7
. The substrate
3
is wound on a roller
1
, to be conveyed in a direction A, and the coating agent
7
is applied thereto from a slit die
5
arranged at a side of the roller
1
.
The slit die
5
has a supply flow path with a delivery opening at the end and, into this flow path, the coating agent within a tank
9
is fed by action of a pump
11
. An open/close valve
15
is installed on a piping
13
upstream the slit die
5
and is controlled by a controller
17
. The controller
17
detects a non-coated part of the intermittently coated substrate
3
by a sensor
19
and controls the open/close timing of the valve
15
, thereby forming a non-coated part. The slit die
5
is rotatable about a support shaft
20
from a solid-line position a two-dot chain line position.
FIG. 2
illustrates another conventional intermittent coating system C
2
. This intermittent coating system C
2
is arranged such that on a substrate
23
that is conveyed in a B direction while being wound on a roller
21
there is coated a coating agent on a coating roller
25
that rotates in the reverse direction. A doctor knife
29
is disposed above the coating roller
25
.
When moving a end of this knife
29
toward or away from the coating roller
25
, the coating agent is intermittently adhered on the coating roller
25
and, by transferring this coating agent on the substrate
23
, an intermittent coating process is executed.
When having interrupted the supply of the coating agent by the open/close valve
15
in the coating system C
1
, a coating drip occurs from the delivery opening due to the residual pressure in the supply flow path and as a result it is difficult to obtain a coat film having a uniform thickness. When rocking the slit die
5
to the two-dot chain line in order to prevent this, a larger length of time is needed for the execution of the coating process to that extent, with the result that the productivity is decreased.
In addition, the coating agent is coated on the substrate
3
on the roller
1
and therefore the coating form is a type of one-side surface coating. Further, intermittent control is performed by sensing the non-coated part. Therefore, it is difficult to increase the coating speed and thereby compensate for the decrease in the productivity.
Further, when having restarted the supply of the coating agent by opening the valve
15
, the coating agent at the end from which coating is started builds up due to the residual pressure. In this respect as well, it is difficult to obtain a coat film having a uniform thickness.
A high precision of the another coating system C
2
is needed for positioning the coating roller
25
to the substrate
23
and for positioning the knife
29
to the coating roller
25
. As a result, the relevant cost increases.
Further, the coating agent makes its flowing movement over the coating roller
25
and therefore the uniformity in the thickness of the coat film is impaired.
In addition, the coating form is a type of one-side surface coating as in the case of the coating system C
1
and therefore this coating system C
2
has a drawback in terms of the productivity.
SUMMARY OF THE INVENTION
The invention has been achieved with such points in view.
It therefore is an object of the invention provide an intermittent coating system and method which make it possible to obtain the coating speed that is relatively high, in addition make it possible to form a coat film having a uniform thickness, and make it also possible to realize this at a relatively low cost.
It is also an object of the invention provide an intermittent coating system and method which provides a relatively high productivity.
According to an aspect of the invention, there is provided an intermittent coating system which comprises a coating agent source that delivers a coating agent at a constant flow rate, a flow path that guides the coating agent thus delivered, a die unit that coats the coating agent supplied from the flow path on a surface of a substrate, an accumulator that is communicating with the flow path and accumulates the coating agent at an upstream position of the die unit, and a controller that controls the volume of the accumulator.
According to this aspect of the invention, the coating agent delivered from the coating agent source, whose flow rate is fixed, is guided along the flow path and is supplied to the die unit at the flow rate that corresponds to a change in the volume of the accumulator communicating with this flow path at the upstream position of the die unit and thus is coated on the surface of the substrate.
If the volume of the accumulator is fixed, the coating agent whose flow rate is fixed is supplied to the die unit and the coat film formed thereby becomes uniform in thickness. If the volume of the accumulator is increased, the coating agent is drawn thereinto, whereby the supply thereof to the die unit is interrupted. And as a result the intermittent coating becomes possible. If the volume of the accumulator is largely changed, it is possible to draw in the coating agent part that is being supplied to the downstream side as well as the increment in the amount of the coating agent supplied from the upstream side. And as a result neither drip nor fall of the coating agent from the die unit occurs and the end edge of the coat film becomes defined or sharpened. The coating agent thus drawn in may be recovered at the non-coating time or may partly be used for shaping at the coating start time. The present system performs the intermittent coating process through the control of the flow rate and therefore can execute a relatively high precision coating at a relatively low cost.
Preferably, the accumulator is comprised of an accumulation chamber and a fitting member that is slidably fitted into the accumulation chamber and the controller includes a drive mechanism for driving the fitting member.
Preferably, the fitting member comprises a piston member, a rubber plate member or an elastic plate number.
Preferably, the drive mechanism includes a cam corresponding to an intermittent cycle and a cam follower that is engaged with this cam.
Preferably, the system further comprises another flow path that guides the coating agent delivered at a constant flow rate, another die unit that coats the coating agent supplied from this another flow path on a reverse surface of the substrate, and another accumulator that is communicating with the another flow path and accumulates the coating agent at the upstream position of the another die unit.
According to another aspect of the invention, in order to attain the above object, there is provided an intermitted coating method which comprises the steps of discharging a coating agent at a constant flow rate, guiding the delivered coating agent along a flow path and supplying it to a die unit, coating the coating agent supplied to the die unit on a surface of a substrate, and accumulating the coating agent guided along the flow path at an upstream position of the die unit and thereby interrupting the supply thereof to the die unit and thereby dwelling the coating thereof on the surface of the substrate.
In order to attain the above object, according to still another aspect of the invention, there is provided an intermittent coating system, wherein a die unit for coating a coating agent on an obverse surface of a substrate being conveyed is disposed close to the surface of the substrate, and provided with a coating agent supply flow path having an open delivery port, and an accumulation
Ide Akinori
Sakai Yoshiyuki
Yoshikawa Tatsuya
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
Lamb Brenda A.
Toshiba Kikai Kabushiki Kaisha
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