JPH0356795B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is applicable to photographic materials such as photographic film and photographic paper, photolithographic materials, magnetic recording materials such as magnetic recording tape, pressure-sensitive recording paper, and heat-sensitive recording paper. This invention relates to an improvement in the process of applying a liquid coating composition to a continuously running long flexible support (hereinafter referred to as "web") in the production of recording materials, and more specifically, to a method for treating the edges of the coating layer. It is.

[Prior art]

In the above-mentioned coating process, due to the action of the surface tension of the liquid coating composition, a thick coated film part is generated at both edges in the width direction of the web, and this thick film part is dried in the subsequent drying process. Since it causes non-uniformity, it is desirable to remove it before the drying process. U.S. Pat. No. 2,899,339 discloses that in such a process, nozzles are provided at both edges in the width direction of the web for sucking up the coating liquid, and the nozzles have an L-shaped double tube structure, and the outer circumference of the nozzles is A method and apparatus are disclosed in which a spray or jet stream of a diluent/solvent is supplied from a central portion and a coating liquid is sucked together with the diluent/solvent from a central portion.

When the present inventors attempted the coating process disclosed in the above-mentioned U.S. Patent No. 2,899,339, the spray or jet stream of the diluent/solvent supplied from the outer periphery of the suction nozzle did not reach the tip of the nozzle and was absorbed. It was found that the intended treatment of the edges of the coating layer could not be carried out sufficiently. On the other hand, in JP-A No. 56-73579, a liquid is ejected from the center of a suction nozzle having a double pipe structure onto a thick coating area, and this liquid and the coating liquid in the thick coating area are combined into the suction nozzle. A method of producing a coated product has been proposed that uses suction, but even with such a method, the liquid ejected from the center of the suction nozzle may go around to the back side of the web, that is, the opposite side to be coated, or the surrounding area. This causes inconveniences such as contaminating the pass rollers of the machine.

[Purpose of the invention]

An object of the present invention is to provide a coating method and apparatus that does not produce a thick coated film on both edges in the width direction of the web and provides a uniform coating thickness over the entire width of the web.

[Structure of the invention]

The above-mentioned object of the present invention is to provide a coating method in which a coating liquid is applied to a web on a back-up. This is achieved by a method and apparatus for imparting.

The endless belt device has a coating film removal mechanism,
The coating film removal mechanism is composed of a suction nozzle, but if a position control device is further added to the endless belt device, the coating width can be changed in accordance with changes in the web width.

Hereinafter, an example of the apparatus of the present invention in which the coating film removal mechanism of the endless belt apparatus is a suction nozzle and is further provided with a position control device will be described in more detail based on the accompanying drawings.

FIG. 1 schematically shows the process according to the present invention using the hopper coating method. FIG. 2 is a perspective view showing details of the application section, and FIG. 3 is a sectional view from the center thereof.

In FIGS. 1 to 3, a web 2 is wound around a coating back-up roller 1 and transported.
A coating head 3 is installed adjacent to the coating head 3. Coating liquids 10 and 11 are supplied to the cavities 4 and 5 in the coating head 3 by metering pumps 8 and 9 through main supply pipes 6 and 7, and ribbon-shaped liquids are supplied through slit-shaped openings 12 and 13 communicating with the cavities 4 and 5. It is extruded and flows down the slide surface in layers. The two coating liquid layers contact each other and flow down the slide surface without mixing, reaching the bead portion 14, where two layers are coated simultaneously. The decompression chamber 15 is equipped with a vacuum pump 16
A back pressure supply means for bead stabilization is combined with a bead stabilizing back pressure supply means.
Coating guide plates 17 and 18 are provided on the coating head.

Endless belts 19, 1 running parallel to both sides of the web 2 in the width direction on the bucking roller 1
Apply the coating liquid to the coating width end portion 9', and form the coating film 20, 2.
0' is shown in FIG.
By keeping the distance between the web 2 and the endless belts 19, 19' at 2 mm or less, uniform coating is possible without destroying the crosslinks.

In FIG. 1, the coating liquid carried by the endless belt 19 is removed from the belt 19 by a suction nozzle 40 or the like. The belt 19 detects the amount of displacement of the web end detected by the end detection mechanism 25 attached to the web 2, which is indicated by 26.
Move it in the width direction using an EPC roll mechanism, etc.

In FIG. 4 showing an example of the coating film removal mechanism according to the present invention, coating films 20, 20' of the coating liquid at the coating width end are shown.
is removed by suction from the end belts 19, 19' by suction nozzles 40, 40', 40'', 40, respectively, and collected in a waste liquid tank (not shown).28
is a punching roll for suction removal. The endless belts 19, 19' are as shown in FIG.
It returns to the application section via the EPC device operating end 26.

In FIG. 5, which shows the position control device provided to the end belt device of the present invention, the control section 32 determines the control amount based on the end position signal sent from the detection section 25, and operates the The endless belts 19, 19' are controlled adjacent to the web 2 by changing the direction of the ends 26, 26'. Such a position control device is generally called an EPC device (edge position controller device), and is often used for the purpose of adjusting the path of the web. , 19' are activated to follow. Therefore, it is necessary to reversely connect the operating end of a commercially available EPC device to the control section and make adjustments to determine the control amount.

FIG. 6 schematically shows the process when the coating head in FIG. 1 is a curtain coat type coating head 3'. Application is possible.

In the present invention, the endless belt may be made of a plastic film, a thin metal sheet, synthetic rubber, or a composite support such as a plastic film and paper. For example, polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate and polyethylene-2,6-naphthalate, and polyamides such as 6,6-nylon and 6-nylon can be used for the plastic film.

Thin metal sheets include Al, SUS304,
SUS316 etc. can be used.

As the coating film removal mechanism, the suction nozzle described in U.S. Pat.
The suction nozzle described in No. 141123 is also applicable.
7 and 8 are diagrams showing an example of a suction nozzle, in which endless belts 19, 19' carrying coating films 20, 20' run in a direction perpendicular to the paper surface, and the coating films 20, 20'' is removed by suction nozzles 40, 40'. The suction nozzles 40, 40' have cleaning liquid jet ports 45, 45' and a suction port 46 at their tips.
The jet ports 45, 45' are located at positions offset from the axes 47, 47' of the double pipes, and the suction ports 46, 46'
is provided at the central axis of the double pipe. Figure 7/8
In the figure, reference numerals 48 and 48' indicate cleaning liquid supply ports.Water, solvent, etc. are supplied through a supply pipe (not shown), and the cleaning liquid is supplied to spout ports 45 and 45' through spirally connected structures 49 and 49'. Sent, coating film 2
0 and 20' respectively. In FIG. 7, reference numerals 50 and 50' denote exhaust ports, through which the edges of the wet and diluted coating layer are removed together with a cleaning solution through an exhaust pipe (not shown). A vacuum pump or the like is usually connected to the exhaust pipe.

The web used in the present invention includes paper, plastic film, metal, resin coated paper, synthetic paper, and the like. The material of the plastic film includes, for example, polyolefins such as polyethylene and polypropylene, vinyl polymers such as polyvinyl acetate, polyvinyl chloride, and polystyrene;
Polyamides such as 6,6-nylon and 6-nylon, polyesters such as polyethylene terephthalate and polyethylene-2,6-naphthalate, polycarbonates, and cellulose acetates such as cellulose triacetate and cellulose diacetate are used. Further, the resin used for resin coated paper is typically polyolefin such as polyethylene, but is not necessarily limited thereto. Further, as the metal web, for example, there is an aluminum web.

[Effects of the Invention] According to the present invention, the coating liquid is applied to the endless belt running parallel to both sides in the width direction of the web at the coating liquid applying portion, so that the coating liquid is applied to the endless belt running parallel to both sides in the width direction of the web. It is possible to obtain a uniform coating thickness over the entire width of the web without producing a thick coating portion at both edges in the direction, and the following effects can also be obtained.

(1) The load on the coating machine drying zone is reduced.

(2) There is no need to cut and remove the edges, improving yield.

(3) The coating film removal mechanism can be installed in a separate room from the coating chamber and drying chamber of the coating machine, so the coating machine can be kept clean.

(4) Product quality will not deteriorate even if the paint film removal mechanism does not fully operate.

(5) If a position control device is provided to the endless belt device, the coating width can be changed instantly in response to changes in the web width, making it possible to continuously change the coating width and improving the operating rate.

[Brief explanation of drawings]

Fig. 1 is a side view schematically showing the process according to the present invention, Fig. 2 is a perspective view showing details of the application section, and Fig. 3 is a side view schematically showing the process according to the present invention.
The figure is a sectional view of the center side. FIG. 4 shows the first embodiment of the coating film removal mechanism in the apparatus of the present invention.
It is a top view seen from the figure A-A' plane. FIG. 5 is a plan view of a position control device provided to the device of the present invention. FIG. 6 is a side view schematically showing another embodiment of the present invention. FIG. 7 is a partial sectional view schematically showing another example of the coating film removal mechanism, and FIG. 8 is a front view of its suction nozzle. 1...Buckling roller, 2...Web, 3,
3'...Applying head, 19,19'...Endless belt, 26,26'...EPC roll, 40,4
0′...Suction nozzle.

Claims (1)

[Claims] 1 In a coating method in which a coating liquid is applied to a web on a back-up roll, a coating liquid is applied to an endless belt running parallel to both sides in the width direction of the web at the coating liquid application part, and A coating method characterized in that the coating film on the endless belt is removed by suction before the coating liquid applied portion at the end of the endless belt returns to the coating liquid applied portion.