JPS6218222B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improved structure of a painting blade, and in particular, to obtain a uniform coating film, the present invention relates to a painting blade in which the amount of paint flowing out is uniform over the entire coating width and is even at the beginning of flowing out, in order to obtain a uniform coating film. Regarding the improved structure of

Conventionally, when forming a coating film thicker than several microns on a drum or sheet, coating methods such as spraying and dipping are often used. However, in this application method, tetrahydrofuran,
Benzene, toluene, methyl ethyl ketone 1 and 2
- When coating with a paint containing a low boiling point organic solvent such as dichloroethane, the smoothness of the paint film surface may be impaired and the unevenness may be approximately 5 μm or more. For this reason, a coating method using a blade (referred to as a blade method) has come to be used for coating with the above-mentioned paint in order to obtain a highly smooth coating film.

This blade method is a coating method in which the atmosphere in which the coating is applied is saturated in advance with solvent vapor in order to reduce evaporation of the solvent of the coating material. Also,
The blade has a structure in which two plate-like members are arranged side by side so that the apexes of the "V" shape have a cross section shaped like non-parallel lines (〓/) slightly apart, and the narrow gap (called the outlet) between them is However, in order to make the coating thickness uniform over the coating width of this blade, that is, the width of the outlet, the flow rate of the paint is increased over the entire width. It is desired that the amount of paint flowing out is uniform and that the timing at which the paint starts flowing out is also the same.

The purpose of the present invention is to provide a blade that satisfies such demands, and the present invention has a first liquid reservoir having a paint inlet;
It comprises a second liquid reservoir having a slit-shaped outlet, and a flow path communicating between these liquid reservoirs and having at least one narrowed part, and the cross section of the narrowed part is approximately parallel to the outlet. The first,
The width of the second reservoir and flow path is achieved by a coating blade that is approximately equal to or wider than the width of the outlet.

Examples thereof will be described in detail below with reference to the drawings.

FIG. 1 is a partially cutaway perspective view of a blade according to the present invention, FIG. 2 is a sectional view, and FIG. 3 is a sectional view of another embodiment.

In the figure, 10 and 20 are liquid reservoirs, 11 is an inlet, 21 is an outlet, 30 is a flow path, and 40 is a defossification pipe 41, which is a valve.

As shown in the figure, the widths of the liquid reservoirs 10, 20 and the outlet 21 of the flow path 30, that is, the lengths in the direction perpendicular to the plane of the paper in FIGS. In Figure 3, the gap in the left-right direction of the paper is narrowed and shallow at the flow path 30 and the outlet 21. The liquid reservoir 10 and the liquid reservoir 20 are connected to a flow path 30.
The liquid reservoir 10 is provided with a circular inlet 11 approximately at the center of its width, and the liquid reservoir 20 is provided with an outlet 21 having a small depth (as described above, that is, a slit-shaped cross section). It is being Therefore, if paint A is poured from the inlet 11 as shown by the arrow in FIG. 2 or the white arrow in FIG.
The paint A flows in the order of 0, the liquid reservoir 20, and the outlet 21, and reaches a predetermined member 60 to be coated. In addition, if a defoaming pipe 40 is connected to the liquid reservoir 10 as shown in FIG. 3, and one end of the defoaming pipe is connected to a vacuum source (not shown) via a valve 41, the valve 40
1, the small air bubbles 50 mixed in the paint can be discharged to the outside of the blade together with some of the paint.

Even if this defoaming pipe 40 is connected to the liquid reservoir 20, substantially the same effect can be obtained.

Now, FIG. 4 is a simplified diagram showing the AA' fracture surface of the blade in FIG. 2, and the arrows in the diagram indicate the flow of paint.

Here, to explain the behavior of the paint, first, the paint that flows in from the inlet 11 has a small flow area and a high flow velocity. However, the depth (or gap) of the flow path 30 is small, and the flow velocity of the paint that attempts to pass through the flow path 30 is reduced by the viscous resistance of the paint, so that the flow of the paint is reduced to a liquid reservoir. 1
0, it is expanded in the width direction. This expansion of the flow in the width direction is also the same between the outlet 21 and the liquid reservoir 0. As a result, the paint is evenly distributed over the entire width of the blade outlet.

Further, in the flow path 30 and the outlet 21, the viscous resistance of the paint acts effectively, and uniformity of the flow velocity of the paint in the width direction is promoted. Therefore, the flow velocity of the paint flowing out from the outlet 21 has the same value at any position.

Furthermore, when the paint starts flowing, the liquid reservoir 1
Waiting for the paint to fill up at points 0 and 20, the speed at which the paint flows through the flow path 30 and the outlet 21 increases, and the time at which the paint finishes passing there is made uniform in the width direction. The time at which paint begins to flow out is approximately the same at any position across the width of the blade.

In addition, when the blade is separated from the coated surface at the end of painting, if the area near the outlet 21 is sharp and the area of the end surface close to the member to be coated 60 is small, as shown in FIG. It was found that by sucking up excess paint with the defoaming pipe shown in the figure, the paint drains better, and as a result, there is no bulge (sag) at the end of coating of the paint film.

Next, an example in which the present invention is specifically applied will be described.

EXAMPLE Coating was carried out by bringing a blade close to the drum in an atmosphere substantially saturated with a solvent while rotating the drum.

B. Composition of paint (photoreceptor solution) Poly-N-vinylcarbazole (BASF Luvican M-170) 48.3g 2,4,7-trinitro-9-fluorenone (Eastman Kodak) 78.8g Acrylic resin (Mitsubishi Rayon BR-107) ……12.1g Latrahydrofuran (Kanto Chemical) ……1200ml B Coating conditions Drum rotation speed 200rpm Paint flow rate 15ml/min Solvent specific vapor pressure≡Solvent vapor pressure/saturated vapor pressure 80% C. Coating results Film thickness: 20 μm Circumferential direction ±1 μm Film thickness variation: Axial direction ±0.5 μm As described above, according to the present invention, it is possible to obtain a coating film, such as a photoconductor coating film, having an extremely smooth surface. .

Note that the inlet 11 is not limited to having a circular cross section, and the flow path 30 may not have one constriction as shown in the figure, but may have a constriction on both sides with a liquid reservoir in between, for example. Even if it is provided, it has the same effect.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway perspective view of a painting blade according to the present invention, and FIG. 2 is a sectional view of the painting blade.
FIG. 3 is a sectional view of another embodiment, and FIG. 4 is a simplified explanatory view showing the inside of the blade. DESCRIPTION OF SYMBOLS 10, 20...Liquid reservoir, 11...Inlet, 21...Outlet, 30...Flow path, 40...Defoaming pipe, 41...
Valve, 50... air bubble, 60... member to be coated, A... paint.

Claims (1)

[Scope of Claims] 1. A first liquid reservoir communicating with a defoaming pipe connected to a vacuum source having a paint inlet, a second liquid reservoir having a slit-shaped outlet, and these liquid reservoirs. a flow path having at least one narrowed portion communicating between the first and second liquid reservoirs and a flow path having at least one narrowed portion, the cross section of the narrowed portion being formed in a slit shape approximately parallel to the outlet; A painting blade having a width that is approximately equal to or wider than the width of the outlet. 2. The device according to claim 1, characterized in that a member near the outlet is made to protrude so that the area of the end of the outlet near the coating surface facing the coating surface is reduced. Painting blade.