JPH10761A - Metal powder recovery method and recovery device - Google Patents

Abstract

(57) [Summary] [Object] In a printing apparatus or a coating apparatus using an intaglio, metal powder such as doctor abrasion powder generated during printing or coating is efficiently collected. It is very effective in improving the quality of printed matter by preventing ink adhesion to the shaft. SOLUTION: By disposing a magnet M so as to generate a magnetic field on the surface of an intaglio cylinder 13, metal powder is magnetically attracted from the surface of the intaglio cylinder 13 passing through the magnetic field. It is preferable to arrange the magnet M at a position after doctoring. Further, the magnet M may be arranged at a position immediately before the doctor ring, or may be arranged at both positions.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for efficiently recovering metal powder mixed in ink with metal powder mainly containing doctor wear powder in a printing apparatus or a coating apparatus using an intaglio. In particular, by collecting metal powder such as doctor abrasion powder generated on the plate surface and the edge of the plate during doctoring, the doctor is prevented from being damaged by the metal powder, and high printing without printing dirt or coating unevenness. The present invention relates to a technique for obtaining high-quality printed matter and painted matter.

[0002]

2. Description of the Related Art FIGS. 1 and 2 show a typical method of collecting foreign matter in ink in conventional gravure printing in accordance with two types of inking systems.

In the inking method shown in FIG. 1, a furnisher roller 1 is placed in an ink pan 11 containing ink I.
This is a method in which the ink I is supplied to the plate surface of the cylinder 13 by rotation of the cylinder 2, and is generally called a finisher dipping method. The ink I supplied to the plate surface of the cylinder 13 is scraped off by the doctor 14, and the ink remaining in the concave portion of the plate surface is transferred by the impression cylinder 15 to the web W pressed against the cylinder 13 to form an image. In this method, the ink I is supplied from the ink reservoir 17 to the ink pan 11 by the pump 16, and the excessively supplied ink overflows from the ink pan 11 and is collected in the ink reservoir 17 through the hose 18. . And
Filters F (three in FIG. 1) are attached at predetermined positions in the ink circulation path for removing foreign matter in the ink.

In the inking method shown in FIG. 2, the ink I is sucked up from an ink reservoir 21 by a pump 22 and is ejected from a nozzle 23 between a furnisher roller 24 and a cylinder 25 so that the ink I is supplied to the cylinder 25. The system is supplied, and is generally called a furnisher bank system. The ink I supplied to the plate surface of the cylinder 25 is scraped off by a doctor 26, and the ink remaining in the concave portion of the plate surface is transferred to a web W pressed against the cylinder 25 by an impression cylinder 27 to form an image. It is similar to that of In this method, an excess amount of the ink I supplied to the cylinder 25 is collected in an ink receiver 28 and stored in an ink reservoir 2.
Collected in 1. Also in this method, filters F (three in FIG. 2) are attached at predetermined positions in the ink circulation path for removing foreign matter in the ink.

As the filter F for removing foreign matter as described above, a filter of a laminate type or a mesh type is generally used. However, the filter F is usually 50 μm due to a problem of insufficient ink supply caused by pressure loss due to clogging or the like. A size capable of removing the above foreign substances is selected. Further, a magnet may be used for the purpose of collecting metal powder. In this case, a method of adding the magnet to a filter structure or a method of putting the magnet itself into an ink pan is adopted.

[0006]

Generally, in a doctor ring structure in gravure printing, the blade of a doctor blade is pressed against a cylinder surface with a linear pressure of 0.3 to 1.2 kgf / cm. Wear progresses, and doctor wear powder generated with the wear is mixed into the ink. Then, the doctor wear powder mixed in the ink damages the doctor blade edge during doctoring, so that doctor streaks and fog defects occur in printed matter. In addition, the doctor abrasion powder is caught between the blades of the doctor, thereby causing poor doctor stain on printed matter. Not only gravure printing but also printing and coating using intaglio such as anilox roll for flexographic printing, such fine defects become fatal defects of the product, especially for wound products As a result, the entire winding becomes defective and cannot be used.

As described above, in order to prevent this, doctor wear powder is conventionally removed by using a filter or a magnet together with the filter, but the particle size of the doctor wear powder is about 0 to 200 μm. Among them, most are 20 μm or less, and the abrasion powder having such a small particle diameter easily damages the doctor blade. However, removal by the filter alone is 5
There is a problem that it is not possible to collect abrasion powder of 0 μm or less. Looking at the system in which a magnet is added to the filter structure, the furnisher dipping system in FIG. 1 only filters the ink supplied from the pump, and the doctor abrasion powder always flows from the cylinder surface after doctoring. The doctor wear powder always exists in the ink pan because the ink is continuously supplied, and even in the finisher bank system shown in FIG. 2, the efficiency of magnetically absorbing and collecting the wear powder from the ink is not so high. Also, regarding the system in which a magnet is put into the ink pan, the collection efficiency of doctor wear powder is insufficient.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a printing apparatus or a coating apparatus using an intaglio, in which a doctor wears out during printing or coating. It is an object of the present invention to provide a method and a device for collecting metal powder, which can efficiently collect metal powder such as powder.

[0009]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a method for collecting metal powder according to the present invention is directed to a method for recovering ink by using a metal powder mainly composed of doctor wear powder generated when doctoring an intaglio surface. A method of recovering metal powder mixed in the apparatus, wherein a magnetic field is generated on the surface of the intaglio, and the metal powder is magnetically attracted to the surface of the intaglio passing through the magnetic field. It is preferable to generate a magnetic field on the surface of the intaglio at the position after doctoring. Further, a magnetic field may be generated on the surface of the intaglio at a position immediately before the doctor ring, or both may be used in combination.

[0010] Further, the metal powder recovery device according to the present invention comprises:
This is a device that collects metal powder that is mixed in the ink with metal powder mainly consisting of doctor abrasion powder generated when doctoring the intaglio surface, and uses magnets to generate a magnetic field on the intaglio surface. It is characterized by being arranged. And it is preferable to arrange | position a magnet in the position after doctoring. Further, the magnet may be arranged at a position immediately before the doctor ring, or may be arranged at both positions.

[0011]

FIG. 3 is a schematic view showing an example of a printing apparatus for performing a method for collecting metal powder according to the present invention. The apparatus shown in the figure is of the same type as the one shown in FIG. 1 in which a furnisher is immersed. A magnet M for collecting doctor wear powder is additionally attached to the apparatus shown in FIG. In this example, two magnets M are attached to the position after the doctor ring, and both magnets M are arranged in proximity to the surface of the cylinder 13 so as to generate a magnetic field. In the usual doctoring method,
Doctor ring 1 hour, doctor width per 10cm, 20
30,000-40,000 doctor wear powder of μm or less
Pieces (measured with a liquid particle counter, the same applies to the following)
However, by arranging the magnet M as shown in FIG. 3, the wear powder generated at the time of doctoring is magnetically attracted to the magnet, so that it can be efficiently collected before being mixed into the ink I in the ink pan 11. Can be.

In the present invention, the collection rate of the abrasion powder greatly differs depending on the position where the magnet is installed. FIG. 4 illustrates the installation state of the magnets. FIG. 4A shows a case where a plurality of magnets M are arranged over the lower half circumference of the cylinder 13, and FIG. When the magnets M are arranged, FIG.
(C) shows the case where one magnet M is arranged at the position after doctoring. FIG. 5 shows the results of the abrasion powder collection test in these installation states in comparison with the case without the magnet. In FIG. 4, the distance between the magnet M and the plate surface of the cylinder 13 is 10 mm, and the magnetic flux density on the plate surface is 1000 G.

From the test results shown in FIG. 5, it is most effective to install a plurality of magnets M over a half circumference of the cylinder 13 as shown in FIG. It can be seen that the concentration of abrasion powder in the ink has been reduced (the effect may be up to 1/20 depending on the test). However, it is practically difficult to mount a plurality of magnets M over a half circumference of the cylinder 13, and FIG.
Even if the magnet M is arranged at the position immediately before the doctor ring as in (b), the recovery effect is halved. Therefore, it is actually necessary to arrange the magnet M at the position after the doctor ring as shown in FIG. Good. According to the test results shown in FIG. 5, the installation at only this position has an effect close to 90% of that at the time of installation around half a circumference.

Looking at the installation distance of the magnet M with respect to the cylinder 13, the recovery efficiency increases as the magnet M is installed closer to the plate surface of the cylinder 13, but if the magnet M is too close, the ink on the plate surface comes into contact with the magnet and the plate surface The pattern formed above may be disturbed. Practically, it is preferable to install the magnet M at a distance of 3 to 10 mm from the plate surface of the cylinder 13.

FIG. 6 is a graph showing the result of the wear powder recovery test when the magnet M is disposed at the position after doctoring as shown in FIG. This is shown in comparison with the case of FIG. This figure 6
As can be seen from FIG.
The collection efficiency of the abrasion powder hardly changes between 0 G and 1,000 G. Therefore, it can be said that a plate surface magnetic flux density of about 1,000 G is sufficient.

FIG. 7 shows the magnetic field distribution of a normal ferrite magnet and a strong magnet specially processed to have a particularly strong magnetic flux density. The stronger the magnet, the better, but on the other hand, there is a concern about the effects on the cylinder and peripheral devices (magnetization of metal parts, generation of electromotive current, malfunction of electronic equipment, etc.). It is preferable to select a type having a magnetic field line distribution as shown in FIG. In other words, ordinary ferrite magnets like this have a magnetic field that spreads around the magnetic pole and affect the surroundings, but specially processed strong magnets do not have this point because the magnetic field lines pass near the magnet. No worries. For example, a general ferrite magnet (maximum magnetic flux density 4,000 G) has a magnetic flux density of 500 G at 10 mm from the magnetic pole and 100 G at 50 mm, whereas a specially processed strong magnet (maximum magnetic flux density of 10,000).
(00G or more) is 1,000G at 10mm and 0 at 50mm
G. The cylinder is usually plated with copper, and the inner iron core is basically hardly magnetized by the diamagnetic effect of copper. For example, a magnet with a maximum magnetic flux density of 4,000 G
The normal iron was magnetized to 50 G by contact for 0 seconds, while the cylinder was about 2 G under the same conditions.

The present invention can be applied not only to gravure printing but also to other printing apparatuses and coating apparatuses having a doctoring mechanism. Further, not only doctor wear powder generated at the time of doctoring but also other metal powder can be removed at the same time. Further, as the magnet to be used, an electromagnet having the same magnetic force can be used.

[0018]

As described above, according to the present invention,
By generating a magnetic field on the surface of the intaglio plate, the metal powder is magnetically attracted from the surface of the intaglio plate passing through the magnetic field, so that the metal powder mainly composed of minute doctor abrasion powder generated during doctoring can be efficiently used. Can be collected
As a result, it is possible to prevent printing stains and coating unevenness.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a printing method of a soaked finisher method.

FIG. 2 is a schematic diagram illustrating a printing method of a finisher bank method.

FIG. 3 is a schematic view showing an example of a printing apparatus for performing the method for collecting metal powder according to the present invention.

FIG. 4 is an explanatory view illustrating an installation state of a magnet.

5 is a graph showing the results of a wear powder recovery test in each installation state shown in FIG. 4 in comparison with a case without a magnet.

6 is a graph showing a result of a wear powder collection test when the magnet installation distance is changed in the magnet installation state of FIG. 4C in comparison with a case without a magnet.

FIG. 7 is a diagram showing magnetic field line distributions of a normal ferrite magnet and a specially processed strong magnet.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Ink pan 12 Furnisher roller 13 Cylinder 14 Doctor 15 Impression cylinder 16 Pump 17 Ink reservoir 18 Hose F Filter M Magnet

Claims (6)

[Claims] 1. A method for recovering metal powder mixed in ink with metal powder mainly composed of doctor wear powder generated when doctoring the intaglio surface, wherein a magnetic field is generated on the intaglio surface. A method of collecting the metal powder by magnetically attracting the metal powder from the surface of the intaglio plate passing through the magnetic field. 2. The method for collecting metal powder according to claim 1, wherein a magnetic field is generated on the surface of the intaglio at a position after doctoring. 3. The method for collecting metal powder according to claim 1, wherein a magnetic field is generated on the surface of the intaglio at a position immediately before doctor ring. 4. A device for recovering metal powder mixed in ink with metal powder mainly consisting of doctor wear powder generated when doctoring the intaglio surface, and generating a magnetic field on the intaglio surface. A metal powder collecting device, wherein a magnet is disposed so as to cause the metal powder to be collected. 5. The metal powder recovery device according to claim 4, wherein the magnet is arranged at a position after doctoring. 6. The metal powder recovery device according to claim 4, wherein the magnet is arranged at a position immediately before doctor ring.