JP2708893B2 - Liquid circulation system - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a liquid circulation system for maintaining the viscosity of a liquid in a liquid storage tank at a set value.

(Prior Art) A photosensitive drum used in an image forming apparatus such as an electrophotographic copying machine or a printer usually converts an aluminum tube into a liquid containing an organic photosensitive substance and an organic solvent (hereinafter referred to as a coating liquid). It is manufactured by dipping and forming a photosensitive coating film on the outer peripheral surface. In the process of immersing the aluminum tube in the coating liquid, make sure that the thickness of the coating film does not become uneven due to the influence of the organic solvent vapor contained in the coating liquid and the displacement of the coating liquid surface. Usually, the coating liquid in the liquid storage tank is always circulated by the overflow method. The coating liquid used as the photosensitive layer of the photosensitive drum has a tendency to gradually increase in viscosity because the solvent in the components is constantly evaporated due to its properties. When the viscosity of the coating liquid changes, the thickness of the coating liquid changes when the aluminum tube is immersed in the coating liquid to form a coating film on the outer peripheral surface. For this reason, the viscosity of the coating liquid is always kept constant.

FIG. 2 shows a conventional coating liquid circulation system used in manufacturing a photosensitive drum. This circulation system is provided with a stirring tank 2 for coating liquid W and a pump P in the middle of a circulation line L1 for circulating coating liquid W in liquid storage tank 1.
, The filter F, and the automatic viscometer 3 are interposed in this order. The stirring tank 2 is provided with a drip equipment 5 for a solvent supplied from a storage tank 4 in which the solvent is stored. An electromagnetic valve 6 is provided in a line L2 connecting the storage tank 4 and the drip equipment 5. Intervened. The opening and closing of the electromagnetic valve 6 is controlled by an electric signal from the automatic viscometer 3.

According to this circulation system, the coating liquid W overflowing from the liquid storage tank 1 is supplied to the stirring tank 2, and the level of the coating liquid W in the liquid storage tank 1 is always kept constant. . The automatic viscometer 3 compares the viscosity of the coating liquid set in advance with the actual viscosity of the coating liquid fed from the stirring tank 2, and sets the electromagnetic on-off valve 6 based on the comparison value. Opening / closing is controlled. And the circulation line L1
When the viscosity of the coating liquid increases, the electromagnetic on-off valve 6 is opened, and the solvent is dripped into the stirring tank 2.
The viscosity of the coating liquid inside is adjusted. The coating liquid adjusted to a predetermined viscosity in the stirring tank 2 is supplied to the liquid storage tank 1 through the circulation line L1. In this way, even if the solvent of the coating liquid A is constantly evaporated, the viscosity of the coating liquid W in the liquid storage tank 1 is kept constant.

(Problems to be Solved by the Invention) However, in the conventional circulation system, since the automatic viscometer 3 is interposed in the circulation line L1 connected to the liquid storage tank 1, it is generated inside the automatic viscometer 3. Vibration or the like is transmitted to the cleaning liquid W in the liquid storage tank 1 as pulsation. Such pulsation causes uneven coating when the aluminum tube A is immersed in a coating solution to form a coating film of a photosensitive substance on the outer peripheral surface thereof, and a coating film having a uniform thickness is formed. Cannot be formed.

In addition, in the stirring tank 2, the coating liquid W is stirred so that the entire coating liquid W has a constant viscosity, but the effect of the stirring is not transmitted to the coating liquid in the circulation line L1 as much as possible. At low speed. However, when the coating liquid is stirred at a low speed, the solvent dripped from the drip equipment 5 is in a state of floating on the surface of the coating liquid W, resulting in poor mixing. When the mixing failure of the solvent occurs, the coating liquid W is fed from the stirring tank 2 to the liquid storage tank 1 through the circulation line L1 in a state where the viscosity is not properly adjusted. As a result, there is a possibility that the coating film formed on the outer peripheral surface of the aluminum pipe has color unevenness, or the thickness of the coating film becomes uneven.

Furthermore, during maintenance of the automatic viscometer 3, since it is necessary to withdraw the coating liquid from the circulation line L1, the operation of the entire circulation system must be stopped, and as a result, the coating efficiency of the aluminum pipe is significantly reduced. .

The present invention has been made in view of the above problems, and an object of the present invention is to constantly circulate, without pulsation, a liquid whose viscosity has been adjusted with high precision in a liquid storage tank. An object of the present invention is to provide a liquid circulation system in which maintenance of equipment for adjustment and the like is easy.

(Means for Solving the Problems) A liquid circulation system according to the present invention includes a main circulation line for circulating a liquid flowing out of a liquid storage tank to the liquid storage tank via an intermediate tank, and a main circulation line separate from the main circulation line. A circulation line for adjusting the viscosity of the liquid flowing out of the intermediate tank to a predetermined viscosity and circulating the liquid to the intermediate tank, thereby achieving the above object. You.

(Embodiment) FIG. 1 is a schematic diagram showing an embodiment of a liquid circulation system of the present invention. This circulation system is used in a coating film forming step of immersing an aluminum tube in a coating solution containing a photosensitive substance and an organic solvent to form a photosensitive coating film on its outer peripheral surface. .

In this circulation system, the main circulation line LA that circulates the coating liquid W flowing out of the liquid storage tank 1 to the liquid storage tank 1.
And a circulation line LB for viscosity adjustment in which the coating liquid is circulated in order to adjust the viscosity of the coating liquid W, which is separate from the main circulation line LA. In the liquid storage tank 1 in the main circulation line LA, the aluminum pipe A is in a state where the coating liquid W is constantly supplied from the lower side and overflows from the upper side.
Is immersed in the coating liquid W to form a coating film on the outer peripheral surface of the aluminum pipe A.

In the main circulation line LA, an intermediate tank 10 in which the coating liquid W overflowing and flowing out from the liquid storage tank 1 is stored.
Is provided. The intermediate tank 10 is provided with a stirrer 11 for stirring the stored coating liquid W. The coating liquid W in the intermediate tank 10 is filtered by a pump P1 interposed in the main circulation line LA between the coating liquid W and the liquid tank 1.
, And is fed to the liquid storage tank 1.

The circulation line LB for viscosity adjustment supplies the coating liquid in the intermediate tank 10 to the viscosity adjustment tank 12 via the pump P2 and the automatic viscometer 3, and from the viscosity adjustment tank 12 again,
Reflux into the intermediate tank 10. The solvent is supplied to the viscosity adjusting tank 12 from a solvent storage tank 4 for storing the solvent via a solvent line LC. An electromagnetic on-off valve 6 is interposed in the solvent line LC.
The viscosity adjusting tank 12 is provided with a drip equipment 5 connected to the tip of the solvent line LC.
By opening the electromagnetic on-off valve 6 interposed in C,
The solvent is dripped from the drip equipment 5 into the coating liquid in the viscosity adjusting tank 12. The viscosity adjusting tank 12 always overflows the contained coating liquid W,
It is designed to be sent within 10.

The electromagnetic on-off valve 6 interposed in the solvent line LC is controlled to open and close by the output of the automatic viscometer 3 interposed in the viscosity adjusting circulation line LB.

In the liquid circulation system of the present invention having such a configuration, the coating liquid W in the intermediate tank 10 is provided in the main circulation line LA.
Is circulated in the main circulation line LA by the pump P1,
The coating liquid filtered by the filter F is supplied to the liquid storage tank 1. In the liquid storage tank 1, the coating liquid W overflows, and the aluminum pipe A is immersed in the overflowing coating liquid W to form a coating film on the outer peripheral surface thereof. The coating liquid W overflowing from the liquid storage tank 1 flows into the intermediate tank 10.

On the other hand, in the viscosity adjusting circulation line LB, the coating liquid W is circulated from the intermediate tank 10 into the circulation line LB by the pump P2, and the automatic viscometer 3 from the intermediate tank 10 and the automatic viscometer 3 again from the intermediate tank 10. The liquid is returned to the viscosity adjusting tank 12.

In the circulation line LB for adjusting the viscosity, the viscosity of the coating liquid W flowing out of the intermediate tank 10 is constantly measured by the automatic viscometer 3. The reference viscosity of the coating liquid W is set in advance in the automatic viscometer 3.
The reference viscosity preset in advance and the intermediate tank 10
The actual viscosity of the coating liquid W flowing out of the apparatus is constantly compared, and the opening and closing of the electromagnetic on-off valve 6 is controlled based on the comparison value. That is, when the viscosity of the coating liquid W flowing out of the intermediate tank 10 becomes equal to or higher than the reference viscosity preset in the automatic viscometer 3, the electromagnetic on-off valve 6 is opened and the viscosity adjusting tank is opened.
Inside 12, a solvent is instilled by an infusion device 5. In this manner, the solvent is applied to the coating liquid W in the viscosity adjusting tank 12.
Is applied, the coating liquid W in the viscosity adjusting tank 12 is
It overflows and is circulated to the intermediate tank 10. When the solvent overflows from the viscosity adjusting tank 12 together with the coating liquid, the two are stirred and mixed. In the intermediate tank 10, the coating liquid W fed from the viscosity adjusting line LB is stirred at low speed by the coating liquid W in the intermediate tank 10 and the stirring device 11, so that the whole has a constant viscosity. Is done. Thus, the coating liquid W in the intermediate tank 10
Is adjusted to a predetermined viscosity with high precision, and is circulated to the liquid storage tank 1 through the main circulation line LA.

The pulsation generated inside the automatic viscometer 3 is absorbed by the intermediate tank 10 and is not transmitted to the coating liquid W in the liquid storage tank 1. Further, since the coating liquid W in which the solvent has been dripped in the viscosity adjusting tank 12 is mixed before refluxing to the intermediate tank 10, even if the coating liquid W is stirred at a low speed in the intermediate tank 10, In addition, there is no possibility that the solvent floats on the surface of the coating liquid W in the intermediate tank 10. Therefore, due to the pulsation of the coating liquid W and the poor mixing of the solvent, the coating film formed on the outer peripheral surface of the aluminum pipe A immersed in the coating liquid W in the liquid storage tank 1 may have uneven color. There is no possibility that the film thickness becomes uneven. Further, at the time of maintenance of the automatic viscometer 3, it is possible to stop only the operation of the circulation line LB for viscosity adjustment and continue the operation of the main circulation line LA, so that there is no need to stop the operation of the entire circulation system. Also, there is no possibility that the production efficiency of the coated photosensitive drum of the aluminum tube is reduced.

In the above description, the circulation line for the coating liquid W for immersing the aluminum tube is described, but the circulation line of the present invention is also suitably used as a circulation line for handling a liquid whose viscosity is adjusted to be constant. I can do it.

(Effect of the Invention) In the liquid circulation system of the present invention, since the main circulation line of the liquid storage tank and the circulation line for viscosity adjustment are separate lines, the viscosity adjustment of the liquid is performed by the viscosity adjustment. It can be done by the circulation line alone. For this reason, the viscosity can be quickly adjusted in response to the fluctuation of the viscosity of the liquid, and the accuracy of measuring the viscosity of the liquid is improved, so that the viscosity can be adjusted with high accuracy. In addition, since devices for adjusting viscosity, such as automatic viscometers, are interposed in a circulation line for viscosity adjustment that is separate from the main circulation line, the entire system operates during maintenance of those devices. There is no need to stop the operation, and maintenance can be easily performed.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of one embodiment of a liquid circulation system of the present invention, and FIG. 2 is a schematic diagram of a conventional liquid circulation system. 1 ... liquid storage tank, 3 ... automatic viscometer, 10 ... intermediate tank, 12 ... viscosity adjustment tank, W ... coating liquid, LA ...
Main circulation line, LB ... Circulation line for adjusting viscosity.

Claims (1)

(57) [Claims] 1. A main circulation line for circulating a liquid flowing out of a liquid storage tank through an intermediate tank to the liquid storage tank; and a liquid flowing out of the intermediate tank, which is a separate system from the main circulation line. A circulation line for adjusting the viscosity to a predetermined viscosity and circulating through the intermediate tank.