JPH09234851A - Two-blade doctor for gravure printing machine and printing machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make plate fog and doctor streak little remain by providing a suction device through a porous body at a middle part of a two-blade doctor. SOLUTION: In between doctors 21 and 22 formed of parallel blades having lengths in a direction of printing width, a porous body 23 is provided. A sucking mechanism 26 is provided at the back of the porous body 23. The sucking mechanism 26 discharges an ink which is sucked by the porous body 23 from between the doctors 21 and 22 in sequence to the outside of them. Accordingly, an ink which is not scraped by the first doctor 21 is sucked by the porous body 23 even when the ink creeps toward the back side of the doctor blade, so that the ink hardly leaks to the second doctor 22. Even when the ink leaks, the ink which is not scraped is scraped by the second doctor 22. Thus, a defection of so-called plate fog where a small quantity of ink of the whole plate remains due to the non-scraped ink and a defection of so-called doctor streak to be generated due to defection of the second doctor can be eliminated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for filling a concave portion of a plate with ink by leaving the ink only in the concave portion (cell) of the plate by filling ink in the concave portion of the plate and scraping off excess ink around the plate with a doctor. When performing printing (entire solid pattern printing, that is, including a coat) by transferring to a doctor, a doctor is used to scrape out excess ink around and a recess on the plate is filled with ink and the excess ink around it is scratched out with a doctor. Accordingly, the present invention relates to a printing apparatus that prints by leaving ink only in the recesses (cells) of the plate and transferring the ink in a pattern to the printing medium.

[0002]

2. Description of the Related Art Conventionally, ink is filled in the recesses of a plate and the excess ink around the plate is scraped off by a doctor to leave ink only in the recesses (cells) of the plate, and the ink is printed in a pattern (a pattern In any case, it is a doctor for scraping out excess ink in the surroundings when printing is performed by transferring the recessed portions (cells) of the plate, regardless of whether they have a solid pattern similar to that of the plate. And, printing is performed by filling ink in the recesses of the plate and scraping out excess ink around the plate with a doctor, leaving ink only in the recesses (cells) of the plate and transferring the ink in a pattern to the printing medium. As a printing device, there has been a device that uses two blades for the doctor. In particular, there is a case where a single doctor does not suffice enough to squeeze out the ink, and it is necessary to manage the doctor's sufficiency by uniformly and completely squeezing out the ink in all positions in the blade width direction. It wasn't easy even if I was going.

Therefore, since it is difficult to completely scrape out the ink in all the positions in the width direction with only one doctor, the second doctor is supposed to scratch the ink left unscratched by the first doctor. It was thought that it would be done by simultaneous doctoring instead of multiple times of doctoring.

As the structure of the doctor, a doctor, which has conventionally been a single doctor, is merely placed with almost no space, and two doctors are simply placed in parallel.

Further, the printing machine in that case has a structure in which a plate and an ink supply device are provided, and the ink is supplied from the ink supply device to the entire plate including the concave portions (cells) of the plate. Being sure to pass through two doctors to scrape out excess ink around, leaving ink only in the recesses (cells) of the plate, and leaving ink only in the recesses (cells) of the plate Contact (in most cases, the ink does not transfer just by contacting from the plate's recess (cell), so normally not only contact but pressurization) leaves only the plate's recess (cell) It has a structure that allows the transferred ink.

The two doctors in this case are made up of parallel blades having the same length as the width in the print width, which is the same as the conventional doctor. In order to fix or adjust the doctor, A holder is provided.

This doctor holder is provided with a mechanism for adjusting the contact pressure between the blade and the plate and for balancing in the width direction.

There was nothing particularly between the two blades of this two-blade doctor.

[0009]

However, in the conventional two-blade doctor, the occurrence of doctor leakage was suppressed as compared with the one-doctor. However, it still cannot prevent the doctor from leaking sufficiently, and it has various problems that it is necessary to apply a considerable contact pressure to complete the contact between the blade and the plate.

Since the conventional two-blade doctor is simply provided with a plurality of conventional doctors, the ink leaked by the first doctor is spread around the back of the doctor blade and the ink collects. It is called a plate fog in which the accumulated ink eventually goes around to the second doctor, and the second doctor causes a leak of ink, leaving a small amount of the ink on the entire plate due to the ink. There is a drawback that the defects cannot be completely removed.

Further, since the conventional two-blade doctor is simply provided with a plurality of conventional doctors, the ink leaked by the first doctor is spread around the back of the doctor blade and the ink is The accumulated ink eventually reaches the doctor on the second sheet, and a defect called a doctor streak caused by a defect on the second sheet leaves ink at the same point in the printing direction. However, there is a drawback that the defect cannot be completely removed.

According to the present invention, these drawbacks of the prior art are remedied so that the plate fog and the doctor's streak are scarcely left, so that it is possible to perform printing faithful to the pattern similar to the depressions (cells) of the plate. , A 2-blade doctor for gravure printing machines that can perform high quality doctoring, and printing that faithfully prints the same pattern as the recesses (cells) of the plate by leaving almost no such plate fog or doctor stripes. It is an object of the present invention to provide a printing machine that can perform doctoring with high quality by performing the above.

[0013]

According to a first aspect of the present invention, there is provided a two-blade doctor for a gravure printing machine, in which a suction device having a porous body interposed between the two-blade doctors. It is a two-blade doctor characterized by having.

The invention according to the present invention is, in claim 2, characterized in that the side face between the two-blade doctor is partitioned from the outside by a soft partition wall. is there.

According to a third aspect of the present invention, there is provided a printing machine equipped with a two-blade doctor,
The printing machine is characterized in that a suction device via a porous body is provided in the middle of the single-blade doctor.

According to a fourth aspect of the present invention, there is provided a printing machine according to the third aspect, characterized in that the ink is supplied by an ink pan.

According to a fifth aspect of the present invention, the side face between the two-blade doctor is partitioned from the outside by a soft partition wall, and the two-blade doctor according to claim 4 is characterized. is there.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is described in detail below with reference to examples. FIG. 1 is a cross-sectional view of a situation showing a two-blade doctor and a printing machine using the two-blade doctor. A large number of plate recesses (cells) not shown are provided on the surface of the plate 11, and the plate recesses (cells) thus provided are patterned to form a printing pattern as a whole. . However, the depressions (cells) of the plate are the patterns that the ink is desired to finally reach on the printing medium.

The plate 11 shown in FIG. 1 is rotatably supported by a support mechanism (not shown). The rotation direction is fixed, and the ink in the ink pan 13 must be in the doctor 2
It is adapted to rotate in a direction in which it can encounter the printing medium 14 via 1 and 22.

The plate 11 support device (not shown) is
For this reason, it is naturally connected to a driving device such as a motor so that the rotation speed can be controlled so that it can rotate at a uniform speed.

The ink pan 13 need only be a container capable of supporting a liquid, and the shape thereof may be any shape that facilitates ink replenishment. However, when an ink supply device for the ink pan is separately provided. The shape is not particularly limited. However, in the width direction of the plate, it is at least necessary to have a shape that allows ink to contact the entire surface. However, it is customary that the ink contains a solvent, but in some cases it is preferable to make the opening smaller in order to suppress evaporation of the solvent,
Further, in order to make the solvent ratio of the ink constant, the solvent ratio of the ink may be made constant by means such as an ink circulation device, but the smoothing is not limited to these.

The doctor 21 and the doctor 22 are similar to a normal doctor in that ink is filled in the recesses of the plate and the excess ink around the plate is scraped off by the doctor to leave the ink only in the recesses (cells) of the plate and to be printed on the printing medium. When printing by transferring the ink in a pattern,
It is a doctor to scrape out excess ink around.

In this case, the two doctors in this case consist of parallel blades having the same length as the width of the print in the same manner as the conventional doctors. To fix and adjust the doctors respectively, Doctor holders 24 and 25 are independently provided.

This doctor holder is provided with a mechanism for adjusting the contact pressure between the blade and the plate and for balancing in the width direction. Doctor holders 24 and 25 in this case
May be fixed to each other, but if it is better to adjust the contact angle of each, the doctor holder 2
It is better to provide 4, 25 and adjust them independently, but the invention is not particularly limited to this. Further, as long as the doctor holders 24 and 25 support the doctors 21 and 22, respectively, there is an advantage that the conventionally used doctor holders 24 and 25 can be used as they are.

A porous body 23 is provided between the two blades of the two-blade doctor, and a suction mechanism 26 is provided behind the porous body 23. This porous body is plate 11
May be in contact with the ink. However, even if it does not contact, the suction capacity of the suction mechanism 26 on the back side may be used as long as it absorbs the excess ink outside the cell, but it also absorbs the ink forming the print pattern inside the cell. In such a case, such a structure cannot be adopted. In this case, the porous body 23 simply absorbs the ink that comes into contact with it, and the absorbed ink may be absorbed by the suction mechanism 26 at the back. Good.

Further, the porous body may be not only in contact with each other but also in contact with an appropriate pressure, but in the case where the pressure also absorbs the ink forming the print pattern in the cell. , It is not possible to have such a structure. Further, the porous body may have elastic properties, but such a structure cannot be adopted when the elastic properties also absorb the ink forming the print pattern in the cells.

Further, this porous body is made up of doctors 21 and 22.
It may be provided on the entire surface, but it is not necessary to do so, and if it is installed on the entire surface, the doctor 21,
Generally, it is generally provided on the back of the first doctor 21 because it hinders the adjustment of the space between the two.

This is because the ink leaking between the doctors 21 and 22 is generated from the doctor leakage by the first doctor 21, and thus the porous body 23 is formed on the back of the first doctor 21. It is also efficient to provide.

Further, the porous body 23 does not necessarily require a considerable length as a depth as shown in the drawing, but may be a considerably thin one. However, in the case where the porous body 23 is too thin and the suction mechanism 26 sucks the ink directly to also suck the ink forming the print pattern in the cell, the porous body having such a shape is used. Should not be body 23.

The suction mechanism 26 is behind the porous body 23 and has a mechanism for sequentially discharging the ink accumulated in the porous body 23 from the inside of the doctors 21, 22 to the outside of the doctors 21, 22. Although not shown, it is performed by an appropriate means such as a pump. The ink discharged by the suction mechanism 26 may be discarded as it is, but by appropriately performing a recovery process, the ink is returned to the ink pan 13 and then the ink has a circulation structure so that the ink can be used for printing again. May be

In this case, since excess ink is collected by applying a negative pressure between the two-blade doctors, a closed space is provided between the two-blade doctors in order to improve the efficiency of the negative pressure. It is good to do. Specifically, the efficiency is improved if the side surface between the two-blade doctors is partitioned from the outside by a soft partition wall (not shown) to form a space between the two-blade doctors. Of course, the partition wall must be formed in a region where there are no cells in the plate, which is outside the effective printing region. Therefore, since such a partition wall merely prevents air leakage, it suffices to prevent most air leakage. Therefore, if it is soft, its elasticity and stretchability do not matter.

The printing medium 14 is pressed by the pressure roller 12 and filled with ink in the recesses of the plate by a doctor, and the excess ink around the plate is scraped off by the doctor, so that the ink is only in the recesses (cells) of the plate. Printing is performed by transferring the ink by leaving a pattern on the material to be printed in contact with the material to be printed.

Needless to say, such an object to be printed can be made of paper, resin, other flexible base material, or hard base material such as glass, but when pressure is difficult, a blanket roll is used. It is necessary to adopt an offset method, etc., in which the image is transferred once and then printed.

Further, as in the present example, it is not necessary to be used in a rotary printing machine, and a sheet-fed system may be used.
In that case, it is necessary that the two-blade doctor of the present invention can be moved up and down and can be separated from the plate, and the inking device and the material to be printed are also fed by a sheet-fed method or a structure corresponding thereto. Must be

[0035]

[0036]

[Example] A high-pet k (trade name, manufactured by Fuji Shoko Co., Ltd.) blade having a cutting edge of 200 μm was used as the first doctor and EBERLE 18ER- was used as the second doctor
80μm (Fuji Shoko Co., Ltd. product name) Cutting edge 200μ
m was used, but in that case, it was set to be 0.5 mm shorter than the first doctor. In the meantime, in order to adjust the gap between the first doctor and the second doctor, a 600 μm thick parallel spacer was interposed.

The printing machine used was a gravure test coater (GS-3) (made by Nakajima Engineering Co., Ltd.).
Trade name) was used. In this case, the version is 193m
A test piece having a length of 1 m and a length of 1100 mm was prepared, and a 100% pattern of 175 lines was used as a test pattern.
The printing speed was 100 m / min, the doctor width was 1400 mm, the doctor pressure was 2.6 kgf, the printing pressure was 2 kgf, and a polyethylene terephthalate film (45 μm) (manufactured by Toray Industries, Inc.) was used as a printing medium.

For comparison of printing results, a fog densitometer (Macbeth RD914) using reflected light was used.

(Embodiment) In the case of a two-sheet doctor, the fog density in the vicinity of the 175 line 100 density of the printed material after printing is 0.007, and it is clear that there is fog even from the viewpoint of human eyes. understood.

(Comparative Example) In the case of the one-sheet doctor, the fog density in the vicinity of the 175 line 100 density of the printed material after printing was 0.000, and the fog was not found even by the densitometer from the viewpoint of human eyes. It was

[0041]

However, in the conventional two-blade doctor, the occurrence of doctor leakage can be suppressed more easily than in the case of a single doctor, so that the contact pressure for perfect contact between the blade and the plate is low. It became possible to do. For this reason,
With regard to the mechanical system as well, the consideration of distortion and the like was small, and the printing machine could be constructed at a low cost.

Further, the ink leaked by the first doctor is absorbed by the porous body even if the ink goes around the back of the doctor blade, so almost no ink leaks to the second doctor. Even if it leaks, it can be scraped off by this second doctor, and even if it leaks, there is a defect called plate fog in which the ink of the entire plate due to that ink remains little by little. It can be completely removed.

Similarly, the ink leaked by the first doctor is absorbed by the porous body even if the ink goes around the back of the doctor blade. Will not leak out and is called a doctor muscle caused by a defect in the second doctor,
The defect that ink remains at the same point in the printing direction no longer occurs.

As a result of the above, the present invention makes it possible to make the construction of the printing machine simple and inexpensive, and to leave almost no plate fog or doctor streaks, which is similar to the concave portion (cell) of the plate. A 2-flute doctor for a gravure printing machine that can perform doctoring with high quality by performing printing faithful to the pattern, and a plate recess or cell It is possible to provide a printing machine capable of performing doctoring with high quality by performing printing faithful to a pattern similar to that of (1).

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a use state of a two-blade doctor for a gravure printing machine and a printing machine of the present invention.

[Description of sign]

 11 plate 12 pressure roller 13 ink pan 14 printed material 21 doctor 22 doctor 23 porous body 24 doctor holder 25 doctor holder 26 suction device

Claims (5)

[Claims] 1. A two-blade doctor for a gravure printing machine, comprising a two-blade doctor for a gravure printing machine, and a suction device having a porous body interposed between the two-blade doctor. . 2. The two-blade doctor for a gravure printing machine according to claim 1, wherein a side surface between the two-blade doctor is separated from the outside by a soft partition wall. 3. A printing machine equipped with a two-blade doctor, characterized in that it is equipped with a suction device via a porous body in the middle of the two-blade doctor. 4. The printing machine according to claim 3, wherein the ink is supplied by an ink pan. 5. The two-blade doctor for a gravure printing machine according to claim 4, wherein a side surface between the two-blade doctor is partitioned from the outside by a soft partition wall.