JP4946548B2 - Plate fog prevention device - Google Patents

Description

The present invention relates to an apparatus for preventing quality defects such as plate fog by drying excess ink on a plate cylinder surface in a gravure printing machine.

  In gravure printing, a gravure roll whose surface is engraved with unevenness is dipped in the ink liquid layer, the ink adhering to the convex part is scraped off with a doctor blade, and the ink remaining in the concave part is supported This is a printing method for transferring to (in the case of direct gravure). Therefore, in order to print on the entire surface of the support, the uneven pattern is very fine and is a series of small dots, but it looks as if the entire surface was smooth roll coated by the preparation of printing ink and engraving method A uniform surface finish can be obtained. The application amount is adjusted depending on the shape, depth, mesh, solid content concentration of the ink, and the like of the gravure cell. The doctor blade is made of a hardened steel plate and is elastic with a thickness of 0.2 to 0.3 mm. It reciprocates from side to side to maintain uniform pressure on the gravure roll while maintaining uniform edge wear ( ± 10 mm).

  The ink ribbon for sublimation transfer according to the present invention is printed by separately printing each color of cyan, magenta, yellow, black and protective layer in each printing unit of the gravure printing machine by the gravure printing method. It is made by. That is, in each printing unit, the pattern of each color rectangular pattern is engraved as an image line part in an approximately quarter area of the cylinder, and the image line part is printed on the film substrate, and the other three-quarters are printed. The area has a pattern configuration in which ink is not applied as a non-image portion and only the fixed positions of the respective colors are printed sequentially in each printing unit. Hereinafter, such pattern printing is referred to as sequential printing. Therefore, as shown in FIG. 5, the image line portion of the gravure plate (hereinafter referred to as “plate cylinder”) handled this time has one side of the rectangular portion parallel to the plate cylinder axis.

  By the way, in the case of gravure printing, since the doctoring is performed on the plate to which the ink is attached, the ink should not be scraped off in the non-image area, but the printing speed is high. As a result, the ink slips through a slight gap between the plate surface and the doctor blade, and an extremely thin ink film remains on the non-image area of the plate. A defect in which this ultra-thin film of ink is transferred to a base material of a color to which the ink should not be transferred is called “plate fog”.

  When printing ink ribbon for sublimation heat transfer, the thickness of the ink in the image area is usually about 10 to 100 μm, while the ink film thickness remaining in the non-image area is 0.1 to 1 μm. When another ink is overcoated with another printing unit, it becomes a so-called ink contamination state, which causes defective products such as color density unevenness of specific colors when it is thermally transferred to photographic paper in the subsequent process. It is. Experience has shown that “plate fog”, which causes this density unevenness, is not a problem unless residual ink is transferred from the plate surface to the film substrate.

  Therefore, in the prior art, “plate fog” was prevented by using a method of blowing and drying the ultrathin film ink remaining on the plate surface (see JP-A-63-227341). According to the publication, when air drying is performed on the image area, when the plate depth is shallow, the solid content of the ink is high, and the solvent evaporation rate is high, the plate is “clogged” (cell Ink accumulates in the inside of the cell, and a cell is a hole in which the plate surface is sculpted), so that intermittent blown air that synchronizes the rotation of the plate and the blown air timing is blown only to the non-image area. Is going. In addition, since new ink does not enter the cell in the “clogged” plate, naturally, it is not transferred to the film base material, resulting in poor printing.

Constituent elements of the plate fog prevention device using this intermittent air blow are composed of a blower, an air switching valve, a blow pipe, a blow nozzle, and a pattern detection unit. As an operating principle, first, air generated by a blower is blown intermittently by an air switching valve based on a signal coming from a pattern detection unit, and the air is sent to a blower pipe and faces the axial direction of the plate cylinder. This is a mechanism in which air is intermittently blown to the plate surface from a considerable number of blowing nozzles attached to the blowing pipe. Therefore, by design, the air from the nozzle should be blown in the non-image portion (non-picture portion) region, and the air blow should stop in the image portion (picture portion).

See JP-A-63-227341

  However, when the printing speed has been increased, the timing of discharging and discharging air from the nozzle to the air switching valve has begun to be delayed due to the effects of air inertia resistance and compressibility. During high-speed rotation of the plate cylinder, air blowing stopped at the boundary at the beginning of the image area, and air blowing started at the later boundary. In other words, a phenomenon has occurred in which air is not blown to an image line portion where air should not be blown or air is not blown to a non-image line portion where air should be blown.

Originally, while the plate cylinder is rotating, air must stop at the boundary of the image line that comes first, and air must be discharged at the position of the subsequent boundary. When this happens, this phenomenon occurs. Therefore, since air is blown to the image area, the above-described “clogging” of the plate occurs, and air is not blown to a part of the non-image area, which causes “plate fogging”. Decided to do.

As a result of various studies in order to solve the above problems, the present inventor is an apparatus that dries excess ink on the plate cylinder surface and prevents quality defects such as plate fogging. An air switching valve that switches between blowing and stopping so that air is blown at the non-imaged portion of the plate cylinder surface and airflow is stopped at the imaged portion, and five directions that branch the air sent from the air switching valve to the branch pipe A branch pipe, and an air nozzle attached to a blower pipe that is fed with air from the branch pipe and faces in the axial direction of the plate cylinder, and the five-way branch pipe is at the center of the outlet bottom of the branch pipe One approximately five pyramids circumscribing five exit circles, and five approximately three pyramids circumscribing two exit circles adjacent to the outlet bottom surface and inscribed in the side wall of the branch pipe I found a plate fogging prevention device, characterized in that, the onset Which it has led to.

That is, in order to blow out the air in a timely manner, the present inventor collides with the inner wall at a right angle while the air enters from the inlet of the branch pipe and exits to the plurality of outlets in the conventional five-way branch pipe. By realizing such a shape, the air itself was prevented from being compressed and the flow velocity was attenuated, and the air blowing by opening and closing the air switching valve and the response of the air blowing were successfully improved.

As described above, according to the plate fog prevention apparatus using the air five-way branch pipe of the present invention, air is blown out on the boundary line from the image line portion to the non-image line portion on the rotating plate cylinder surface. Air blowing can be accurately performed on the boundary line between the image line portion and the image line portion. Therefore, printing defects such as “clogging” that has conventionally been caused by blowing air to the image area and “plate fog” that has been caused by the delay in blowing air to the non-image area can be reliably resolved. I was able to do it.

  Hereinafter, the present invention will be described in more detail with reference to the drawings.

  FIG. 1 is a block diagram showing a conventional intermittent blower, which is the same as the present invention except for the inside of the five-way branch pipe 4. The intermittent air blower includes a blower 1, a switching valve 2, a five-way branch pipe 4, an air pipe 5, and an air nozzle 7.

  The operating principle is that air generated by the blower 1 is blown intermittently by the switching valve 2, divided into five directions by the five-way branch pipe 4, and reaches the air nozzle 7 through the air pipe 5. The air is intermittently blown to the plate cylinder 8 through the air nozzle 7.

  That is, air is blown against the non-image portion 10 of the plate cylinder 8 to dry the remaining ink, and the air blowing is stopped against the image line portion 9 of the plate cylinder 8, This prevents the ink transferred to the image line 9 from being dried.

Further, as a mechanism for intermittently sending air, a sensor for detecting the non-image portion 10 and the image portion 9 of the plate cylinder 8 is separately prepared, and the switching valve 2 is operated by a signal from the sensor. The corresponding solenoid valve controls the air flow.

FIG. 2 is a cross-sectional view showing the configuration and operating principle of a conventional 5-way branch pipe 4. It can be seen that the air 13 entering from the entrance collides with a right-angle wall surface in the air traveling direction inside the five-way branch pipe and generates a vortex inside the pipe. It can be seen that the movement of the air 13 causes the air itself to be compressed and the flow velocity to be reduced, and the timing of blowing and blowing from the sensor is distorted.

  FIG. 3 is a cross-sectional view showing the configuration and operating principle of the five-way branch pipe 17 of the present invention. The cut surface of the cross section is parallel to the direction of the air 20 flowing through the branch pipe. Conventionally, a substantially pentagonal pyramid-shaped object is fixed to the center bottom surface where the air 20 has collided, and a substantially triangular pyramid-shaped object is fixed to five locations on the peripheral bottom surface. ing.

In such a shape, the air 20 that has entered from the air inlet 18 flows so as to slide on the tapered surface along the air traveling direction inside the pipe, and is divided into five by the tapered dividing portion. From five air outlets 19, the air pipe 5 is sent to the air nozzle 7. Since no air collision occurred at any place, the compression and recovery of the air 20 were suppressed, and the physical change of the air in the air branching in the five directions was greatly alleviated.

FIG. 4 is a cross-sectional view of the five-way branch pipe 17 having a cut surface cut at a right angle to the air traveling direction in the five-way branch pipe 17 (cross section AA in FIG. 3). The five-way branch pipe 17 has one air inlet 18, one five-way branch point (the apex of the substantially five-pyramid 14) 16, five branch portions (approximately the three-pyramid 15), and five places. The air outlet 19 is provided. In contrast to this figure, air flows from the paper surface toward the paper back.

FIG. 5 shows a substantially pentagonal pyramid 14 fixed inside the five-way branch pipe 17, and FIG. 6 shows a substantially triangular pyramid having a tapered side wall fixed on the side surface inside the five-way branch pipe 17. FIG.

As an effect of such a shape inside the five-way branch pipe, when the air generated by the blower passes through the five-way branch pipe, the air collision on the inner wall surface of the five-way branch pipe is alleviated, Since compression and recovery are suppressed, the response speed of air discharge and discharge to the conventional valve switching can be dramatically increased.

Configuration diagram of intermittent blower Working principle of conventional 5-way branch pipe Working principle of the 5-way branch pipe of the present invention Sectional view of the 5-way branch pipe of the present invention Perspective view of approximately five pyramids Perspective view of a nearly triangular pyramid

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Blower 2 Switching valve 3 Exhaust 4 5-way branch pipe 5 Air pipe 6 Blower pipe 7 Air nozzle 8 Plate cylinder 9 Drawing part 10 Non-drawing part 11 Air inlet 12 Air outlet 13 Air 14 About five pyramid 15 About three pyramid Body 16 5-way branch point 17 5-way branch pipe 18 Air inlet 19 Air outlet 20 Air

Claims (1)

A device that dries excess ink on the plate cylinder surface and prevents quality defects such as plate fogging,
The air generated by the blower is blown at the non-image area of the plate cylinder surface, and the air switching valve for switching between blowing and stopping so that the air flow is stopped at the image area, and the air sent from the air switching valve is branched. A five-way branch pipe that branches into a pipe, and an air nozzle attached to a blower pipe that is fed with air from the branch pipe and faces the axial direction of the plate cylinder,
The five-way branch pipe has one approximately five-sided pyramid circumscribing five outlet circles in the center of the outlet bottom face of the branch pipe, and circumscribes two outlet circles adjacent to the outlet bottom face. A plate fog prevention apparatus comprising: five approximately three pyramids inscribed in a side wall.

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