JPH08267714A - Method and device for supplying powder - Google Patents

Abstract

PURPOSE: To solve sanitary and health problems of operators and prevent generation of offset without damaging glossiness of a printed matter. CONSTITUTION: A paper delivery cylinder 23 is covered with an insulating film 13. After the insulating film 13 is electrified, a powder 5 of a controlled quantity is attracted to the insulating film 13, and the insulating film 13 is made to come into contact with an ink face of a printing paper 8 immediately after printing. Thus, the powder 5 attaches to only undried inked parts selectively, so that environmental contamination caused by splash of the powder is prevented and sanitary and health problems of operators can be solved. As control property of a supply quantity of powder is excellent and the fewest possible powder attaches to the undried ink, offset can be prevented without damaging glossiness of a printed matter.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a powder supply method and apparatus applied to prevent sticking (set-off) between printing papers due to undried ink in a paper discharge section of a printing machine.

[0002]

2. Description of the Related Art Conventionally, in a sheet-fed printing machine or the like, in order to prevent a trouble due to adhesion (set-off) between printing papers due to undried ink, printing papers are printed on a paper discharge section of the printing machine as shown in FIG. A powder supply device for preventing set-off is provided by spraying powder 5 such as starch on the printing surface of No. 8.

In the powder supply device shown in FIG. 6, compressed air is supplied to the powder container 4 while the compressed air is being supplied 20 to the powder container 4.
Compressed air containing the powder 5 is blown onto the ink surface of the printing paper 8 from the powder container 4 → the nozzle 21 to adhere the powder 5 to the printing surface of the printing paper 8. FIG. 7 shows another conventional example of a powder supply device that has been proposed to prevent the powder from scattering.

In the powder supplying apparatus shown in FIG. 7, the plastic film 25 wound around the discharge cylinder 23 is charged by frictional charging by the roller 28, and the powder 5 sprayed from the powder spraying mechanism 27 is charged. The plastic film 25 is attached to the plastic film 25, then the plastic film 25 is moved around the discharge cylinder 23, and the plastic film 25 and the printing paper 8 being conveyed are brought into contact with each other so that the powder is applied to the printing surface of the printing paper 8. Attach it.

In FIG. 7, 22 is a printing cylinder, 24 is a paper pressing roller, 26 is a powder introduction tube, and 28 is a powder spraying mechanism 27.
, 29 is a printing paper conveying device.

[0006]

In the powder supply device shown in FIG. 6, the powder 5 is scattered around the sheet discharge section of the sheet-fed printing press, and the surrounding environment is significantly deteriorated. Further, the powder 5 attached to the undried ink on the printing paper 8 scatters during the subsequent handling process, which adversely affects the hygiene and health of the operator.

Further, in the powder supply device shown in FIG. 7, the powder 5 is electrostatically carried on the paper discharge cylinder 23, so that the amount of the powder 5 scattered is slightly reduced, but the powder spray mechanism 27 is used. Since it is adopted, there is a problem that scattering around the powder 5 cannot be avoided. The present invention is proposed in view of the above problems, and an object of the present invention is to provide a powder supply capable of solving the problem of hygiene and health of the operator and preventing settling off without losing gloss of a printed matter. A method and an apparatus are provided.

[0008]

In order to achieve the above-mentioned object, the powder feeding method of the present invention is such that a discharge cylinder is covered with an insulating film, and the insulating film is charged and then controlled. The amount of powder thus obtained is adsorbed to the insulating film, then the insulating film is brought into contact with the ink surface of the printing paper immediately after printing, and the powder is selectively applied only to the undried ink portion of the printing paper. It is characterized by being attached (Claim 1).

Further, the powder supply apparatus of the present invention comprises at least an insulating film coated on the paper discharge cylinder, a charging means for charging the insulating film, and a means for controlling the powder supply amount. Item 2). In the powder supply device, the charging unit may be configured to perform frictional charging or corona charging by bringing at least one of a flexible blade and a flexible roller into contact with the insulating film. 3).

In the powder supply device, the powder supply amount control means includes a powder supply source, a rotary roller carrying the powder on the surface thereof, and a predetermined amount of the powder on the surface of the rotary roller as an insulating film. It may be configured by a fur brush that controls the powder supply amount by transferring the powder. In the powder supply device, after the powder is directly supplied from the powder supply source to the insulating film, the fur brush is brought into contact with the insulating film and rotated, and at the same time, vacuum suction is applied to obtain a predetermined amount of powder. The amount of powder supplied may be controlled by collecting the body while leaving it on the insulating film (claim 5).

In the powder supply device, the powder and undried ink adhering to the non-ink portion of the printing paper are removed by a vacuum suction device which is arranged on the downstream side of the discharge cylinder and close to the ink surface of the printing paper. The weakly bound powder may be removed by suction to reduce the amount of the powder adhering to the printing paper (claim 6).

[0012]

The powder feeding method and apparatus of the present invention are configured as described above, and the discharge cylinder is coated with an insulating film, the insulating film is charged, and then a controlled amount of the powder is supplied. Since the body is adsorbed on the insulating film, and then the insulating film is brought into contact with the ink surface of the printing paper immediately after printing, the powder selectively adheres only to the undried ink part, and environmental pollution due to powder scattering Is prevented, and the problem of hygiene and health of the operator is solved. In addition, the controllability of the powder supply amount is good, and the minimum necessary amount of powder adheres to the undried ink, so the set-off is prevented without losing the gloss of the printed matter.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an example of the constitution of a powder supplying apparatus used for carrying out the powder supplying method of the present invention will be explained with reference to FIG. 1 (a). Output cylinder 23
Insulating film 13 covering the powder, and powder source 1
The rotary roller 2, the fur brush 3, the flexible blade 10, the powder recovery box 11, and the vacuum suction device 12a.

In FIG. 1A, 8 is a printing paper, 9 is ink on the printing paper 8, and 3a in FIG. 1B is the fur brush 3 described above.
The shafts 3b and 3b are the bristles of the fur brush 3. Teflon is used as the surface coating material for the insulating film 13 and the rotating roller (φ50 mm) 2. Fur brush 3,
The thing used for the cleaning part of the usual copying machine is diverted.

A rubber blade is used as the flexible blade 10. The flexible blade 10 has two functions of triboelectric charging of the insulating film and powder recovery.
A vacuum cleaner is diverted to the vacuum suction machine 12a, and the suction port is modified so as to open in a slit shape by the width of the printing paper. This suction port is provided at a position about 20 m away from the printing paper 8. Has been done.

The rotation speed of the discharge cylinder 23 is set to 3 m / s. Starch powder (particle size: about 3 μm) is used as the powder 5, and the rotating roller 2 rotates while contacting with the powder 5 of the powder supply source 1. Therefore, the surface of the rotating roller 2 is powdered by frictional charging. Covered by 5. The fur brush 3 is in contact with the rotating roller 2 and the insulating film that covers the paper discharge cylinder 23, and serves to convey the powder 5 on the rotary roller 2 to the paper discharge cylinder 23.

By increasing or decreasing the number of rotations of the rotary roller 2, the amount of powder supplied to the paper discharge cylinder 23 can be controlled. The ink surface of the printing paper 8 to which the ink is transferred from the blanket is
The discharge cylinder 23 is contacted at a constant speed. Here, the powder 5 is electrostatically adsorbed to the insulating film 13 of the paper discharge cylinder 23,
Since the adhesive force of the undried ink is larger than the electrostatic attraction force, the powder 5 adheres only to the undried ink portion.

The powder 5 mechanically attached to the non-ink portion of the printing paper 8 and the powder 5 weakly bound to the undried ink are sucked and collected by the vacuum suction device 12a.
This vacuum suction device 12a is not always necessary. on the other hand,
The powder 5 remaining on the discharge cylinder 23 side is scraped off by the flexible blade 10, collected, and reused.

FIG. 2 shows the relationship between the rotational speed of the fur brush 3 and the amount of powder adhering to the solid printing paper. When the rotation speed of the fur brush 3 is 1000 rpm or more, the powder adhesion amount is saturated. FIG. 3 shows the relationship between the rotation speed of the rotating roller 2 and the amount of powder adhered to the solid printing paper. As the number of rotations of the rotary roller 2 increases, the powder adhesion amount also increases.

When the powder adhesion amount is 150 particles / cm ² or less, set-off occurs. On the other hand, the powder adhesion amount is 800 pieces / cm ²
If it exceeds the range, the gloss of the printed surface will decrease. Powder adhesion amount 350
When the density is up to 500 pieces / cm ² , there is no set-off and no decrease in gloss, and a stable and good printed matter can be obtained. Further, the above experiment was conducted for about one month, but almost no scattering of powder to the surroundings was observed.

In the experiment for obtaining the data shown in FIGS. 2 and 3,
Although the vacuum suction device 12a was not used, the vacuum suction device 12
When a is also used, the amount of powder adhered to the solid printing paper finally obtained is 500 even if the experiment is carried out at the rotation speed of the rotating roller where the powder adheres to the solid printing paper at about 2000 particles / cm ^2. It was suppressed to about / cm ² . That is, the margin of the rotation speed of the rotating roller is greatly expanded. First, a large amount of powder 5 is attached to the printing paper 8, and then excess powder 5 is applied by vacuum suction.
From the viewpoint of preventing ink from adhering to the insulating film 13, it is preferable to collect the.

In the experiment using the vacuum suction device 12a together, almost no powder was scattered around. The present invention is not limited to the above embodiment. For example, as shown by a broken line in FIG. 1, a flexible roller (rubber roller) 6 may be added to increase the charge amount of the insulating film 13.

Further, the same effect can be obtained by charging with the corona charger 7 as shown by the broken line in FIG. By doing so, it is possible to remove the powder 5 that happens to be mechanically attached to the non-ink portion of the printing paper 8. In addition to Teflon, most of the materials for the insulating film 13 can be used, including polyethylene terephthalate (mylar), nylon, and the like, as long as they are in the category of plastics and eventually insulators.

As the material of the flexible blade 10, most of them can be used as long as they are in the rubber category including silicon rubber. Other materials can be used as long as they have flexibility. In addition to the starch, the powder 5 is
Many powders such as plastic powder can be used. FIG. 4 shows another embodiment in which the belt 2'is used instead of the rotating roller, and in this embodiment, the same operation as described above is performed.

FIG. 5 shows still another embodiment.
In this embodiment, after the powder is directly supplied from the powder supply source 1 to the insulating film 13, the contact suction rotation of the fur brush 3 ′ and the vacuum suction device 12b having the suction port surrounding the fur brush 3 ′ are provided. Thus, the powder is collected while leaving a predetermined amount on the discharge cylinder 23. The powder supply source 1 is formed in a hopper shape, and a portion of the powder supply source 1 in contact with the discharge cylinder 23 is a flexible silicone rubber valve so that excess powder is not supplied to the insulating film. There is. The amount of powder on the discharge cylinder before contacting the printing paper is controlled by the rotation speed of the fur brush and the vacuum suction force. In a proof-of-principle experiment, it has been confirmed that the amount of powder adhering to solid printing paper can be controlled to about 500 pieces / cm ² .

[0026]

As described above, the powder feeding method and apparatus of the present invention coat the discharge cylinder with an insulating film, charge the insulating film, and then control the powder in a controlled amount. Since it is adsorbed on the insulating film and then the above-mentioned insulating film is brought into contact with the ink surface of the printing paper immediately after printing, the powder can be selectively attached only to the undried ink part, and environmental pollution due to powder scattering can be prevented. As a result, it is possible to solve the problem of hygiene and health of the operator.

Further, the controllability of the powder supply amount is good, and the necessary minimum amount of powder adheres to the undried ink, so it is possible to prevent set-off without losing the gloss of the printed matter.

[Brief description of drawings]

FIG. 1A is a side view showing a first embodiment of a powder supply apparatus used for carrying out a powder supply method of the present invention, and FIG. 1B is a side view showing a fur brush. Is.

FIG. 2 is an explanatory diagram showing the relationship between the rotation speed of a fur brush and the amount of powder adhering to solid printing paper.

FIG. 3 is an explanatory diagram showing the relationship between the number of rotations of a rotating roller and the amount of powder adhering to solid printing paper.

FIG. 4 is a side view showing a second embodiment of the powder supply device used for carrying out the powder supply method of the present invention.

FIG. 5 is a side view showing a third embodiment of the powder supply apparatus used for carrying out the powder supply method of the present invention.

FIG. 6 is a side view showing an example of a conventional powder supply device.

FIG. 7 is a side view showing another example of a conventional powder supply device.

[Explanation of symbols]

 1 Powder Supply Source 2 Rotating Roller 3 Fur Brush 3a Shaft of Fur Brush 3 3b Hair of Fur Brush 3 Powder 6 Flexible Roller 7 Corona Charger 8 Printing Paper 9 Ink 10 Flexible Blade 11 Powder Recovery Box 12a Vacuum suction device 13 Insulating film 23 Paper ejection cylinder

Claims (6)

[Claims] 1. A discharge cylinder is coated with an insulating film, the insulating film is charged, a controlled amount of powder is adsorbed to the insulating film, and then the insulating film is printed. A powder supply method characterized in that the powder is selectively attached only to the undried ink portion of the printing paper by bringing it into contact with the ink surface of the printing paper immediately after. 2. A powder supply device comprising at least an insulating film coated on a discharge cylinder, a charging means for charging the insulating film, and a powder supply amount control means. 3. The charging unit according to claim 2, wherein the charging unit is configured to perform frictional charging or corona charging by bringing at least one of a flexible blade and a flexible roller into contact with the insulating film. Powder feeder. 4. The powder supply amount control means transfers a powder supply source, a rotating roller carrying the powder on the surface thereof, and a predetermined amount of the powder on the surface of the rotating roller to an insulating film. 3. The powder supply device according to claim 2, wherein the powder supply device controls the powder supply amount. 5. The powder is directly supplied from the powder supply source to the insulating film, and then the fur brush is brought into contact with the insulating film and rotated, and at the same time, vacuum suction is applied to a predetermined amount of the powder. The powder supply device according to claim 2, wherein the powder supply amount is controlled by collecting the body while leaving it on the insulating film. 6. A vacuum suction device disposed on the downstream side of the paper discharge cylinder in proximity to the ink surface of the printing paper, weakly bound to powder and undried ink adhering to the non-ink portion of the printing paper. The powder supply device according to claim 2, wherein the powder that has been deposited is removed by suction to reduce the amount of powder that adheres to the printing paper.