Printing – Intaglio – Rotary
Reexamination Certificate
2001-11-07
2003-11-04
Eickholt, Eugene H. (Department: 2854)
Printing
Intaglio
Rotary
C101S157000, C101S350600, C101S367000
Reexamination Certificate
active
06640703
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a gravure printing method using aquatic gravure ink and a printing drum, print material, and equipment such as an ink pan, a furnisher roll, and a doctor knife used for carrying out the method.
BACKGROUND OF THE INVENTION
Conventionally an organic solvent type of (oil) ink has been used in the gravure printing, and for color matching, printing is performed once or repeatedly in the overlaid state using process color ink in which coloring materials for indigo blue, red, yellow, black and white colors are included. When a specific color is required by a customer, toning is performed to satisfy the customer's request. If a large quantity of ink with any specific color is required, a printing firm purchases the ink already toned, by an ink manufacturer, from the supplier. Because of the characteristics of the organic solvent type of ink, to satisfy a customer's requests for coloring performance and gradation, generally a low-mesh (with about 175 lines) and deep (with the depth of 18 to 30&mgr;) printing plate is used.
For the reasons described above, the problems as described below occur in the gravure printing method using the organic solvent type of gravure ink.
1) As the ink is of an organic solvent type, problems occur concerning the working environment in the printing firms, accident prevention, contamination of the environment due to the emission of the gasified solvent to atmosphere. Further, there is the problem of residual solvents, when the material printed with the ink is used as a film for food packaging.
2) When the organic solvent type of ink is used, as the ink dries fast and the gradation in printing is narrow, a deep and low-mesh printing plate is used as described above. In this case a large quantity of ink is consumed. This is a main cause for cost increase in printing.
3) In the conventional gravure printing, printing with the process color ink as described above is performed once or repeatedly, and further as ink with a specific color (required by a customer) is used in many cases, a number of colors and the number of printing plates increase. This results in a time loss due to preparatory steps before the start of printing and a toning loss. Further in a case of ink with a specific color, as the ink can not be used for other purposes, the quantity of left over remaining ink increases. This negatively effects printing cost. Sometimes the remaining ink is discarded, so that improvements are required also from the view point of resource saving.
4) Recently customers in the market require various types of print materials with a small lot to be produced and in addition within a short period of time. With this, the needs for cost management are becoming more and more stringent. Further social attention is more and more concentrated on the problems concerning environmental pollution and sanitary management in food industries. When organic solvent types of ink are used, the social needs cannot be satisfied.
For the reasons described above, a printing method using aquatic gravure ink in place of the organic solvent type of ink is being considered with keen interest. Further, different from the oil gravure ink conventionally used in the art, the aquatic gravure ink insures substantial improvement in the working environment in the printing firms. Because of this feature, it can be expected that the aquatic gravure ink will be used more and more in gravure printing.
When the aquatic gravure ink is used, the problems caused in association with use of organic solvents do not occur. However, aquatic ink has by its nature such deficiencies including the hardness in drying, hardness in resolving in the water solvent, and hardness in wetting a printing plate surface due to the surface tension. When the type board is set by the same technique as that with the organic solvent type of ink currently available in the market, the printing speed becomes lower. In addition such problems as fogging or gradation fault occur on the printing plate, which makes it impossible to obtain high quantity print materials.
2. In the conventional type of gravure printing machine, the size of the ink pan
1
is very large as shown in
FIG. 5
, a large quantity of remaining ink is left in the ink pan
1
(about 20 kg per printing plate). When the ink is the standard color, the ink can be used the next time. However, if the ink is a specific color based on the customer's request, it is necessary to stock the ink until the ink is used the next time. This results in substantial a cost increase.
Especially, when structure of a printing machine using aquatic gravure ink is as described above, due to fogging on the type board caused by hardness of the ink in resolving in a water solvent as an intrinsic defect of aquatic gravure ink, the remaining ink can not be used again, which causes a grave problem in cost management.
In
FIG. 5
, designated at the reference numeral
2
is a furnisher roll, at
3
is a printing drum, at
3
a
is a printing plate surface, at
5
is a doctor blade, at
6
is a pressure drum, and at
7
is a film.
In the conventional type of gravure printing machine, the furnisher roll
2
is provided in the side opposite to the doctor as shown in FIG.
6
. Because of this configuration, when gravure printing is carried out with aquatic gravure ink, wetting failure as an intrinsic defect of the aquatic gravure ink occurs due to the surface tension on a surface of the printing plate, so that, as the printing speed becomes faster, ink on the printing plate drops into the ink pan
1
, which causes blurring on print materials or fogging on the printing plate surface and disadvantageously makes it difficult to perform printing under good conditions.
Further in the conventional doctor knife of gravure printing machine, the length L of a back plate
5
b
projecting from a bracket
5
a
of the doctor blade
5
is set to 30 m/m as shown in FIG.
7
and
FIG. 8
, and the length L
1
of a blade tip of a doctor knife
5
c
is set to 4 m/m, so that, because of the dimensions, the excellent coloring performance to and gradation on a base film are insured when the printing ink is oil ink.
However, when printing is performed with aquatic gravure ink under the same conditions as those employed when printing is performed with oil gravure ink, fogging occurs on a surface of the printing plate due to the doctor cutting fault caused in association with the hardness of the ink in resolving in a water solvent as an intrinsic defect of the aquatic gravure ink, and there occurs the problem that printing cannot be carried out without changing structure of the doctor.
3. In the gravure printing machine using oil ink, as shown in
FIG. 11
, the furnisher roll
2
is provided against the printing drum
3
in the side opposite to the doctor knife
5
, and ink
4
in the ink pan
1
is pumped up by the single furnisher roll
2
and supplied onto the printing plate surface
3
a
. In
FIG. 11
, designated at the reference numeral
6
is a pressure drum, and at
7
is a printed film.
When gravure printing is performed using the aquatic gravure ink, if the conventional structure is unchanged, wetting failure of ink
4
occurs on the printing plate surface
3
a
due to the surface tension as an intrinsic defect of the aquatic ink, and as the printing speed becomes faster, the ink
4
supplied onto the printing plate surface
3
a
drops into the ink pan
1
, and as the result, blurring on print materials and fogging on the printing plate occur, which disadvantageously makes it impossible to perform printing under good conditions.
When gravure printing is performed using the oil gravure ink, the problem described above does not occur, but such problems as blocking occur when the printing plate surface
3
a
is dried after the ink is transferred onto the film
7
, and to prevent this phenomenon, it is necessary to pump up the ink
4
from the ink pan
1
as fast as possible, and to satisfy this necessity, the furnisher roll
2
is provided in the opposite s
Fukumori Hirotsugu
Nakaya Katsumi
Shimizu Michiyoshi
Sugiyama Kimio
Torasawa Toshiyuki
Eickholt Eugene H.
Japan Patent Management Co., Ltd.
McGlew and Tuttle , P.C.
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