Method and apparatus for inking a waterless planographic printing plate

A method and apparatus for inking a "waterless" planographic printing plate utilizes an ink application unit and a separating agent application unit. These two units supply conventional ink and a separating agent either directly or indirectly to the planographic printing plate.

FIELD OF THE INVENTION 
The present invention is directed generally to a method and apparatus for 
inking a "waterless" planographic printing plate. More particularly, the 
present invention is directed to a method and apparatus for inking a 
"waterless" planographic printing plate of a rotary offset printing press. 
Most specifically, the present invention is directed to a method and 
apparatus for inking a "waterless" planographic printing plate of a rotary 
offset printing press having an inking unit which is associated with the 
planographic printing plate. The "waterless" planographic printing plate 
is inked by its associated inking unit which may use conventional printing 
inks or which may use inks particularly adapted for "waterless" printing 
plates. A separating agent application unit is provided separate from the 
inking unit and may be utilized to supply a separating agent directly or 
indirectly to the "waterless" planographic printing plate. 
DESCRIPTION OF THE PRIOR ART 
It is known generally to use so-called "waterless" printing plates in 
offset planographic printing. A description of a printing plate that is 
usable for this "waterless" planographic printing may be found in a 
publication entitled "Toray Waterless Plate" from Toray Industries, Inc. 
Such "waterless" planographic printing plates are also described in U.S. 
Pat. No. 3,511,178 to Curtin and in European Patent No. EP-0-113 925 A2 of 
Toray Industries, Inc. 
These "waterless" planographic printing plates are divided into printing 
areas and non-printing areas. The non-printing areas have a strong 
affinity for conventional inks; i.e. for inks which are not specifically 
adapted for use with "waterless" printing plates. This strong affinity of 
the non-printing portions of these "waterless" planographic printing 
plates for conventional inks results in the covering of these non-printing 
areas with ink when the special "waterless" inks are not used. Once the 
non-printing areas of the "waterless" planographic printing plates become 
covered with ink, they transfer this ink to the sheet or web being 
printed. This, of course, results in unacceptable print quality. The press 
must be stopped and the plates must be removed and cleaned. The only way 
that "waterless" printing plates have been usable in the past is in 
conjunction with special inks which are adapted specifically for use with 
these "waterless" planographic printing plates. Such specially adapted 
"waterless" inks are more expensive than conventional inks and may not 
always perform as well. 
It will thus be seen that there is a need for a method and apparatus that 
will allow conventional inks to be used with "waterless" planographic 
printing plates. The method and apparatus for inking "waterless" 
planographic printing plates in accordance with the present invention 
provides this result and is a significant improvement over the prior art. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide a method and apparatus 
for inking a "waterless" planographic printing plate. 
Another object of the present invention is to provide a method and 
apparatus for inking a "waterless" planographic printing plate of a rotary 
offset printing press. 
A further object of the present invention is to provide a method and 
apparatus for inking a "waterless" planographic printing plate of a rotary 
printing press having an inking unit associated with the planographic 
printing plate. 
Still another object of the present invention is to provide a method and 
apparatus for inking a "waterless" planographic printing plate using 
conventional inks which are not adapted to "waterless" planographic 
printing. 
As will be set forth in detail in the description of the preferred 
embodiments which is presented subsequently, the method and apparatus for 
inking a "waterless" planographic printing plate in accordance with the 
present invention utilizes an inking unit which is in indirect contact 
with the planographic printing plate and a separating agent application 
unit which supplies a suitable separating agent, such as silicon oil, to 
the "waterless" planographic printing plate along a separate path. The 
separating agent application unit may be in either direct or indirect 
contact with the planographic printing plate. This separating agent 
application unit is separate from the ink application unit which can 
supply conventional ink to the "waterless" planographic printing plate. 
A primary advantage of the present invention is that conventional inks can 
be used in the inking unit. This means that special "waterless" inks, 
which contain a separating agent, do not have to be used in the ink 
application unit. The problems involved in ink transfer because of the 
inclusion of separating agents in the ink-feeding roller train are 
eliminated by the present invention. 
Another advantage of the present invention is that the amount of separating 
agent used can be more closely metered. Since the separating agent is 
being applied by a separating agent application unit, the quantity of 
separating agent applied, and the timing of the application can be 
controlled. The application of the separating agent can be adapted to 
various operational stages of a rotary offset printing press during the 
operation of the press. 
The affinity of the waterless ink-repellant, non-printing areas of the 
"waterless" planographic printing plate for conventional ink is reduced by 
the application of the separating agent. These waterless ink-repellant, 
non-printing areas of the planographic printing plate are slightly raised 
above the level of the printing areas of the plate. Since these raised 
areas can be protected by a continuous supply of the separating agent, 
which is supplied in exactly metered amounts, these areas of the 
planographic printing plate are not subjected to as great an amount of 
wear as they otherwise would be. In addition, the provision of a 
separating agent application unit, in accordance with the present 
invention, facilitates the return of used, separating agent to the 
application unit. This accomplishes the cleaning of the planographic 
printing plates. 
While the present invention facilitates the use of conventional printing 
inks with "waterless" planographic printing plates, it does not preclude 
the utilization of special waterless printing inks. It is possible to use 
these special inks, which are adapted to "waterless" planographic printing 
in the printing unit of the present invention. 
The method and apparatus for inking a "waterless" planographic printing 
plate in accordance with the present invention overcomes the limitations 
of the prior art. It is a substantial advance in the art.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring initially to FIG. 1, there may be seen a first preferred 
embodiment of an offset printing unit, generally at 2, in accordance with 
the present invention. This offset printing unit 2 utilizes a rubber 
cylinder 3 as a blanket cylinder, and a similar rubber cylinder 4 as a 
counter-pressure cylinder. These two cylinders 3 and 4 cooperate to print 
a paper web 7 which passes between these two cylinders. An ink image to be 
applied to the paper web 7 by the blanket cylinder 2 is formed by a 
waterless planographic printing plate 8 that is secured to a plate 
cylinder 6. The planographic printing plate 8 is adapted to accomplish 
so-called "waterless" planographic printing. It is provided with 
ink-accepting printing areas 9 as well as with waterless ink-repellant, 
non-printing areas 11. These non-printing areas 11 are elevated slightly 
with respect to the level of the printing areas 9. These various 
cylinders, as well as the additional cylinders and rollers to be described 
subsequently, are all supported for rotation between laterally spaced side 
frames of the rotary offset printing press 2. Only one such side frame 1 
is depicted in the drawings with the other side frame having been removed 
for clarity. It will also be understood that like reference numerals will 
be used to identify like elements in the several preferred embodiments of 
the present invention. 
Referring again to FIG. 1, it may be seen that the rotary offset printing 
unit 2 in accordance with the first preferred embodiment of the present 
invention utilizes an ink application unit 12 that has an ink-conducting 
roller train 13, and a separating agent application unit 14 that has a 
separating agent-conducting roller train 16. These two application units 
12 and 14 both cooperate with the "waterless" planographic printing plate 
8 carried on the plate cylinder 6. A conventional printing ink 17; i.e. 
ink not specifically adapted for "waterless" planographic printing, is 
applied from the ink application unit 12, through its ink-conducting 
roller train 13 to the planographic printing plate 8. A separating agent 
18, such as silicon oil, is supplied to the "waterless" planographic 
printing plate 8 by the separating agent application unit 14 through its 
separating agent-conducting roller train 16. 
As may be seen in FIG. 1, in the first preferred embodiment, the ink 
application unit 12 is a short inking unit 19 that consists of a soft 
application roller 21 which contacts the planographic printing plate 8, a 
screen roller 22, and a doctor device 23. The doctor device 23 is 
preferably a chambered doctor blade and is the source of the conventional 
ink 17. These elements form the short inking unit 19 of the first 
preferred embodiment. The soft ink application roller 21 has a surface 
coating 24, and the screen roller 22 has a coating 26. Both of these 
coatings are ink-accepting. 
In the first preferred embodiment of the present invention, the separating 
agent application unit 14 is embodied as a short application unit 27. This 
short application unit 27 has a soft separating agent application roller 
which is in contact with the "waterless" planographic printing plate 8, a 
screen roller 29, and a doctor device 31, which is preferably a chamber 
doctor blade. The doctor device 31 is the reservoir or source of the 
separating agent 18. The separating agent application roller 28 is 
provided with a soft coating 32 which is separating agent-accepting. This 
coating 32 may be a silicon caoutchouc or rubber, a fluorosilicon 
caoutchouc or rubber, or a silicon oxide. 
In this first preferred embodiment of the apparatus for inking a 
"waterless" planographic printing plate in accordance with the present 
invention, conventional ink 17 and a separating agent 18, such as silicon 
oil, are applied by their respective screen rollers 22 and 29 from their 
respective doctor devices 23 and 31. The ink 17 is applied to the soft ink 
application roller 21 and the separating agent 18 is applied to the soft 
separating agent application roller 28 from the respective screen rollers 
22 and 29. From the soft application rollers 21 and 28, the ink 17 and the 
separating agent 18 are applied to the "waterless" planographic printing 
plate 8. In this process, the non-printing areas 11 of plate 8 are wetted 
with the separating agent 18 while the printing areas 9 of the 
planographic printing plate 8 are wetted with the conventional printing 
ink 17. This method and apparatus thus allows a "waterless" planographic 
printing plate 8 to be used with conventional printing ink 17 by providing 
separate ink application and separating agent application units in the 
form of the short inking unit 19 and the short separating agent 
application unit 27. 
Turning now to FIG. 2, there may be seen a second preferred embodiment of 
an apparatus for inking a "waterless" planographic printing plate in 
accordance with the present invention. In this second preferred 
embodiment, the ink application unit, generally at 12, is provided in the 
form of a generally conventional inking unit 34 instead of the short 
inking unit 19 depicted in FIG. 1. In this second preferred embodiment, as 
seen in FIG. 2, the conventional inking unit 34 includes two ink 
application rollers 36 and 37 that are resting against the printing plate 
8 on the plate cylinder 6. These two ink application roller 36 and 37 are 
in contact with a first ink distributing cylinder 38. The first ink 
distributing cylinder 38, together with a second ink distributing cylinder 
39 and an ink film roller 43 are connected by two interposed ink transfer 
rollers 39 and 42. The first ink transfer roller 41 is in contact with the 
second ink distribution cylinder 39, and the second ink transfer roller 42 
is in contact with the film roller 43, all as seen in FIG. 2. An ink 
ductor roller 44 supplies the ink film roller 43 with conventional 
printing ink 17 which is supplied to the ink ductor roller 44 from an ink 
duct 46. All of the rollers and cylinders in the inking unit 34; i.e. ink 
application rollers 36 and 37, ink distribution cylinders 38 and 39, ink 
transfer rollers 41 and 42, and ink film roller 43, as well as ink ductor 
roller 44 are provided with an ink-accepting coating which may be, for 
example caoutchouc or rubber, or Rilsan. 
In this second preferred embodiment, the separating agent application unit 
14 can be a spray application unit, as depicted at 47 in FIG. 2, instead 
of the short application unit depicted at 27 in FIG. 1. In this spray 
application unit 47 for the separating agent 18, the separating agent 
application roller 48 is in contact with the "waterless" planographic 
printing plate 8 on the plate cylinder 6. The separating agent application 
roller 48 receives separating agent 18 from a separating agent 
distributing roller 49. The separating agent 18 is applied to this 
distributing roller 49 by means of a spray unit 51 which is generally 
conventional in operation and is not described in detail. In this second 
embodiment, the spray unit 51 is the source of the separating agent 18. 
In FIGS. 3 and 4 there are depicted third and fourth preferred embodiments, 
respectively of an apparatus for inking a "waterless" planographic 
printing plate in accordance with the present invention. In the third 
preferred embodiment depicted in FIG. 3, the separating agent application 
unit 14 is a brush application unit 52. In the fourth preferred 
embodiment, as shown in FIG. 4, the separating agent application unit 14 
is a film application unit 53. In these third and fourth preferred 
embodiments, the ink application unit 12 is the short inking unit 19 which 
has previously been described in the first embodiment. 
As may be seen in FIG. 3, the brush application unit 52 includes a 
separating agent application roller 54 which is in contact with the 
"waterless" planographic printing plate 8, and a separating agent 
distributing roller 56 that is in contact with the separating agent 
application roller 54. A separating agent ductor roller 57 receives the 
separating agent 18 from a reservoir and this separating agent 18 is 
transferred from the ductor roller 57 to the distributing roller 56 by a 
generally known brush roller 58. 
As may be seen in FIG. 4, in the fourth preferred embodiment, which 
utilizes a film application unit 53, the separating agent application 
roller 59 is in contact with printing plate 8 on plate cylinder 6 and 
receives separating agent 18 from a separating agent distributing roller 
61. A separating agent ductor roller 62 picks up the separating agent 18 
from its reservoir. As was the case in the previously described 
embodiments, all of the rollers and cylinders in these several separating 
agent application units 14 have coatings which are separating agent 
accepting. 
Turning now to FIG. 5, there may be seen a fifth preferred embodiment of an 
apparatus for inking a "waterless" planographic printing plate in 
accordance with the present invention. In this fifth preferred embodiment, 
the separating agent 18 is applied indirectly to the "waterless" 
planographic printing plate 8. As may be seen in FIG. 5, there is provided 
a short separating agent application unit, generally at 64, in which a 
separating agent application roller 63 of the unit 64 is in engagement 
with the soft ink application roller 21. This separating agent application 
roller 63 transfers separating agent 18 to the soft ink application roller 
21 from a doctor device 31 similar to the doctor device described in 
connection with FIG. 1. The soft ink application roller 21 is thus 
provided with both ink 17 and separating agent 18 and transfers both of 
these to the "waterless" planographic printing plate 8. In this preferred 
embodiment, the separating agent 18 is indirectly supplied to the 
planographic printing plate 8 by the separating agent application roller 
63 through the soft ink application roller 21. In this fifth preferred 
embodiment, the separating agent application roller 63 is provided with a 
hard, separating agent accepting coating 66, such as, for example silicon 
oxide. Additionally, this hard separating agent application roller 63 is 
embodied as a screen roller which cooperates with the doctor device 31. 
In each of the above described separating agent application units 14, the 
coatings of the various rollers and cylinders are all separating agent 
accepting. If these coatings are soft, they may be of silicon or 
fluorosilicon caoutchouc or rubber. If these coatings are hard, they can 
be of silicon oxide, for example. The number of individual rollers in the 
separating agent application units can be variable. It will also be 
understood that the separating agent application roller for each of the 
separating agent application units can be made to be thrown off from or 
moved away from its associated plate cylinder or ink application roller. 
This will stop the supply of separating agent 18 to the "waterless" 
planographic printing plate 8 from the separating agent application unit 
14. This may be desirable if an ink, which is adapted for use with 
"waterless" planographic printing plate 8 is being supplied to plate 8 
from the ink application unit 12 and thus there is no need for the 
separate application of an additional separating agent 18. 
While preferred embodiments of a method and apparatus for inking a 
"waterless" planographic printing plate in accordance with the present 
invention have been set forth fully and completely hereinabove, it will be 
apparent to one of skill in the art that a number of changes in, for 
example, the overall sizes of the various units, the drive assemblies for 
the units, the type of paper web being printed and the like could be made 
without departing from the true spirit and scope of the present invention 
which is accordingly to be limited only by the following claims.