Note: Descriptions are shown in the official language in which they were submitted.
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METHOD OF DRYING PRINTED MATERIAL AND APPARATUS THEREFOR
TECHNICAL FIELD
[0001]
The present invention relates to a printed material drying
method and a printed material drying apparatus, which can
efficiently dry printing ink on printed sides of printed
materials to avoid adhesion of the printed materials with each
other.
BACKGROUND ART
[0002]
When printing is performed on a print side of a printed material
by using ink, it is required to dry the printed ink fixed on
the printed materials quickly for preventing adhesion of the
printed materials with each other by the ink f ixed on the print
side.
[0003]
There has been no formal name for the printed ink drying methods
given by the industry or academic society. However,for, example,
the types of commonly used methods for drying the printed ink
are: oxidation polymerization drying type; infiltration
dryness type; evaporation drying type; ultraviolet rays
stiffening type; infrared rays stiffening type; electron beam
stiffening type; normal temperature nature and dryness type;
and thermal stiffening type mixed reaction type.
[0004]
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As the drying method, typically used is of the oxidation
polymerization type, and the oxidation polymerization type
drying method is used for drying the offset ink, typographic
ink, and the like. With the oxidation polymerization type
drying method, the printed ink is dried in the air by utilizing
the oxygen contained in the air. The next most used drying
method is the evaporation type drying method, which is used for
drying the gravure ink, the rotary offset ink, and the like.
The evaporation type drying method is a drying method with which
ink is dried by being left in the air and by using heated air
obtained from a gas burner, or the like. Further, there is a
penetration type drying method targeting the rotary letterpress
ink, the water-based flexo ink, and the like used as paper ink,
and this drying method is a method with which the ink penetrates
to the fiber of the paper, and dried in the air.
[0005)
Recently, on-demand printing, which is "to print required
number of copies as necessary", has been attracting increasing
attentions, and many on-demand printers are operating in Japan.
For the on-demand printing, liquid type ink called "electol ink"
is used.
[00061
It is necessary for the above-described various types of ink
to be fixed on the print side by some kind of method after being
transferred from a printing plate to a printed material.
Fixation types (drying methods) vary depending on vehicle
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(printing varnish) composition of the printing ink. The
fixation types (drying methods) for various types of printing
ink will now be described in detail.
[0007]
The evaporation drying method is a method which dries and
solidifies the printing ink by evaporating a volatile solvent
contained in the ink. Examples of such ink are quick-drying
photogravure ink using a low boiling point solvent, flexo
(printing varnish) ink, screen ink using a high boiling point
solvent, pad ink, dry offset ink, and water-based ink. This
evaporation drying method is a method that is the most effective
and most employed method for fixing the printing ink on a plastic
material on which infiltration dryness cannot be expected at
all. The drying speed is adjusted according to the kinds of
the solvent. At the same time, drying is accelerated by heat
and hot air generated by a drying machine.
[0008]
The oxidation polymerization type is a method which dries and
solidifies the printing ink by absorbing the oxygen in the air
onto the side printed with ink that includes drying oil as a
main component and by connecting vehicle molecules with each
other into netlike giant molecules. Examples of such printing
ink are letterpress ink (excluding flexo ink) , metal screen ink,
and the like. This oxidation polymerization type requires a
considerable amount of time, so that a metallic soap of
manganese, cobalt, or the like is added as a dryer, and heat
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is applied thereon to accelerate drying.
[0009)
The liquid reaction type is a method which uses one kind of ink
out of two kinds having a resin containing reaction groups as
a vehicle as ink and uses the other kind as a hardener so as
to reaction-cure the printing ink with that combination.
Example of such printing ink are polyurethane resin type gravure
ink for retort pouches, screen ink having=a resin of epoxy type,
melamine type, or the like as a vehicle, pad ink, and the like.
This liquid reaction type mixes the two kinds right before the
use. Thus, after printing, reaction occurs following
evaporation of the solvent, and the reaction is accelerated by
applying heat. Reaction is advanced with the two-kind mixed
ink without printing, so that there is an issue in terms of press
stability. Normally, there are such issues that residual ink
cannot be reused (pot life) , for example, and it is necessary
to be careful in handling. An ink film obtained by stiffening
is strong, and the tolerance thereof is superb.
[0010]
The ultraviolet(UV) rays stiffening type is a method which
irradiates UV rays onto a printed ink film, and has it reacted
instantly to be changed into a solidified film. Vehicles of
UV ink are made with a polymer, a monomer, and a
photopolymerization solvent (accelerator), and a
photopolymerization initiator absorbs the UV rays of specific
wavelength and triggers a chain reaction to cure the ink.
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Development of the UV rays stiffening type drying system has
made it possible to overcome the issue of "drying
characteristic" that is a major difficulty factor for employing
offset printing, dry offset printing, and screen printing to
5 plastics.
[0011}
The infiltration dryness type is a method which is used in a
case where a printing target is a piece of paper, with which
the oil component in the ink penetrates into the paper and the
solid component remains on the surface of the paper to be dried.
Ink used for newspaper, for example, is a typical example of
such printing ink. However, this is unsuitable for printing
applied on print sides of non-absorbent plastics, metals, glass,
and the like.
[0012)
Most of printed materials, particularly magazines, contain a
small amount of cornstarch powder base (maize starch) particles
powder and paper dusts. Those particles powder are used to
lighten generation of static electricity during a process of
drying printing ink so as to avoid sticking of printed materials
with each other, such as sticking of pages in magazines. In
addition, an antioxdant is added to the cornstarch powder base.
Further, it has been also pointed out that "blocking (offset) "
may be less likely to occur when the cornstarch powder base is
sprinkled over the whole surface of printed material. Since
the cornstarch powder base is of microparticles powder, it also
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works to accelerate drying of the ink because the "air" enters
from gaps in the ink.
[0013]
In those on the market, it is clearly written that "antioxdant
(sulfur dioxide) " is contained in all the ingredients. However,
there is no clear explanation regarding why the antioxdant is
used. Sulfur dioxide exhibits effects of inhibited oxidation
and of bleaching. Sulfite, such as sub-sodium sulphide, =is used
asthe material. The explanation often given is that cornstarch
powder base is manufactured by employing a method which extracts
starch after dipping cornstarch in sulfurous acid solution to
have it resolved. This method is called a wet milling
sub-sulfite acid soaking method.
DISCLOSURE OF THE INVENTION
PROBLEMS TO BE SOLVED BY THE INVENTION
[0014]
As the printing ink f ixing method described above, i.e., as the
drying method, there are various methods described above. As
the simplest method, however, the fixing method using the
cornstarch powder base (maize starch) particles powder is
employed.
[0015]
However, since the cornstarch powder base particles powder are
splashed over the whole printed material, it has been pointed
out that this method deteriorates the printing work
environments and the like. Therefore, there has been a demand
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for a low-cost printing ink drying method (fixing method) with
a fine work environment, which can substitute such method.
[0016]
Patent Document 1 discloses a technique which heats food to a
preset temperature by using steam. Patent Document 2 only
discloses a technique which cooks food materials by using
superheated steam, and there is no indication about applying
steam to the printing ink fixing method or about applying steam=
to avoid adhesion of printed materials with each other.
[0017]
Moreover, there is no technical inquiry regarding the
characteristic and property of steam in Patent Document 1 and
Patent Document 2. In addition, there is no indication about
applying steam to the printing ink fixing method or about
applying steam to avoid adhesion of printed materials with each
other.
Patent Document 1: Japanese Unexamined Patent Publication
2003-70644
Patent Document 2: Japanese Unexamined Patent Publication
2003-262338
[0018]
An object of the present invention is to provide a printed
material drying method and a printed material drying apparatus,
which can achieve drying of printing ink by utilizing the Nano
sized high-temperature dryness steam.
MEANS FOR SOLVING THE PROBLEMS
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[0019)
In order to achieve the foregoing object, the printed material
drying method according to the present invention is a printed
material drying method which performs drying processing on a
printed material. The method includes: the Nano sized
high-temperature dryness steam made as a cluster is generated
to the Nano oder; jetting the Nano sized high-temperature
dryness steam to a print side of the printed material; and
imparting intramolecular vibrational energy to ink on the print
side by the Nano sized high-temperature dryness steam.
[0020]
The printed material drying apparatus for embodying the printed
material drying method of the present invention is a printed
material drying apparatus which performs drying processing on
a printed material. The printed material drying apparatus
includes: a steam generating device which generates
high-temperature dryness steam; a cluster generating device
which clusters the high-temperature dryness steam generated by
the steam generating device on Nano oder; and an exciting device
which jets the Nano sized high-temperature dryness steam
generated by the cluster generating device to a print side of
the printed material so as to impart intramolecular vibrational
energy to ink on the print side by the Nano sized
high-temperature dryness steam.
EFFECTS OF THE INVENTION
[0021]
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The present invention makes it possible to dry printing ink and
to avoid adhesion of printed materials with each other securely
and easily by utilizing Nano sized high-temperature dryness
steam.
BEST MODES FOR CARRYING OUT THE INVENTION
[0022]
Hereinafter, embodiments of the present invention will be
described in detail by referring to the drawings.
[0023]
FIG. 1 shows a printing device to which a printed material drying
apparatus according to the embodiment of the present invention
is applied. The printing device shown in FIG. 1 is a device
which prints on a continuous rolled paper, and it is structured
to: hold a printing paper la to a feeding roller 2; perform
printing on a print side of the printing paper la fed out from
the teeding roller 2 at a printing section 3; let already printed
paper lb go through the printed material drying apparatus A
according to the embodiment of the present invention; and takes
up dry-processed paper 1 onto a take-up roller 4.
[0024]
As shown in FIG. 1, the printed material drying apparatus A
according to the embodiment of the present invention is an
apparatus which: accepts the printed paper lb printed by the
printing section 3 into inside a drying chamber 21; dries the
ink on the printed material lb quickly by Nano sized
high-temperature dryness steam; and sends out the dried printed
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material lb towards the take-up roller 4. As shown in FIG. 1
- FIG. 3, the printed material drying apparatus A includes a
steam generating device 5, a cluster generating device 6, and
an exciting device 7.
5 [0025]
The steam generating device 5 generates high-temperature
dryness steam. Specifically, as shown in FIG. 3, the steam
generating device 5 includes a boiler 8 and a water supply tank
9. Water is supplied to the water supply tank 9 via a water
10 feed valve 10, and the water feed valve 10 is controlled by an
upper-limit sensor 11 and a lower-limit sensor 12 to accumulate
water W of a set amount inside the water supply tank 9. The
water W is fed to the boiler 8 from the water supply tank 9 by
a pump 13 through a nonreturn valve 14, and the boiler 8 includes
a heater 15 for heating the supplied water. The boiler 8 heats
the water by the heater 15 to generate high-temperature
saturated steam Ml. Reference numeral 16 is a sensor for
detecting a water level within the boiler 8, 17 is a pressure
relief valve for keeping the pressure within the boiler 8 to
a specific pressure, and 18 is a feeding valve which takes out
the high-temperature saturated steam Mi from the boiler 8.
Further, on the output side of the boiler 8, a pipe 19 for letting
through the high-temperature saturated steam Ml and a tubular
heater 20 wound around the pipe 19 are provided.
High-temperature dryness steam M2 is obtained by letting
through the high-temperature saturated steam Ml within the pipe
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19 that is heated by the tubular heater 20. Note that the boiler
S and the water supply tank 9 of the steam generating device
are merely presented as a way of examples, and the structures
thereof are not limited to those shown in the drawing. The steam
5 generating device 5 may be a type other than the one shown in
the drawing. The point is that the steam generating device 5
may be of any types, as long as it is in a structure capable
of generating the high-temperature saturated steam Ml.
[0026]
The cluster generating device 6 and the exciting device 7 are
placed inside the drying chamber 21 to which the already printed
paper lb is fed by a feeding roller 22. The cluster generating
device 6 and the exciting device 7 will be described in detail.
That is, pipes 23 and 24 are placed in a vertical direction by
sandwiching the feeding roller 22 within the drying chamber 21
as shown in FIG. 1 and FIG. 2. As shown in FIG. 3, a plurality
of nozzles 25 are opened in the pipes 23 and 24 towards the
printed paper lb that runs within the drying chamber 21. The
cluster generating device 6 obtains Nano sized high-temperature
dryness steam M3 made as a cluster is generated to the Nano oder
through spraying the high-temperature dryness steam M2 from the
nozzles 25 of the pipes 23 and 24 (see FIG. 2) . The pipe 23
is placed on the print side of the printed paper lb, and the
pipe 24 is placed on the back face side of the printed material
lb. Distance R2 from the pipe 24 to the printing paper 1 is
set to be shorter than distance R1 that is from the pipe 23 to
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the printing paper 1(Rl > R2). The distances from the pipes
23, 24 to the printed paper lb are not limited to those
illustrated in the drawing but may be changed as appropriate
in accordance with the kind of the printed paper lb. In FIG.
2, it is illustrated to spray the Nano sized high-temperature
dryness steam M3 from a part of the pipe 23. However, it is
sprayed from the whole length of the pipes 23 and 24.
[0027]
As described above, the cluster generating device 6 utilizes
the steam pressure within the boiler 8 to jet the
high-temperature dryness steam M2 from the nozzles 25 of the
pipes 23 and 24 so as to generate the Nano sized high-temperature
dryness steam M3 that is obtained by Nano oder clustering
performed on the high-temperature dryness steam M2 that is
generated by the steam generating device 5.
[0028J
Whether it is a hydrophilic pulp fiber or the printing paper
1 whose printing quality is being improved by applying pigments
painting through improving the smoothness, whiteness, and
opacity, there are apertures as shown in FIG. 4A and FIG_ 4B,
even though there are differences in size of the radiuses of
the fiber pores (capillaries). The cluster generating device
6 jets out the high-temperature dryness steam M2 from the
nozzles 25 of the pipes 23 and 24 to generate the Nano sized
high-temperature dryness steam M3 having the size of several
molecules to several tens of molecules in accordance with the
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property of the printed paper lb described above. For the
cluster generating device 6 to generate the Nano sized
high-temperature dryness steam M3 on the order of several
molecules to several tens of molecules, the cluster generating
device 6 employs a method which adjusts the diameter of the
nozzles 25 opened in the pipe 23 or a method which adjusts the
steam pressure of the boiler 8 to generate the Nano sized
high-temperature dryness steam M3 according to the fiber pores
of the printing paper 1, for example.
[0029]
The inventors of the present invention has analyzed the fiber
pores of the printing paper 1 and found that it is most idealistic
to set the high-temperature dryness steam M2 to be in a size
within a range of several molecules to several tens of molecules
in order to let through the Nano sized high-temperature dryness
steam M3 to the fiber pores of generally-used printing paper
1. The particle diameter of the Nano sized high-temperature
dryness steam M3 obtained by performing Nano oder clustering
on the high-temperature dryness steam M2 was calculated by using
a theoretical formula. The high-temperature dryness steam M3
of 150 - 210 C was sprayed onto the printing paper 1, and the
particle diameter of the Nano sized high-temperature dryness
steam M3 that can keep the moisture content of the printed paper
lb required in the industry of printing within a range of 8.5
- 7.5% was specified within a range of several molecules to
several tens of molecules by using a paper moisture meter K-200
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Manufacturer: KETT) There are various properties of printed
papers lb, particularly those with different fiber pore
diameters, so that it is impossible to specify the lower limit
number of molecules of the cluster to a specific numerical value.
Thus, the lowest cluster molecule number was set as roughly less
than 9, i.e., set as several molecules on calculations. This
was set as the lower limit range of the number of cluster
molecules. Similarly, it is impossible to specify the upper
limit number of molecules of the cluster to a specific numerical
value. Thus, it was verified that the highest cluster molecule
number was about 10 - 90 molecules i.e., verified as several
tens of molecules on calculations. This was set as the upper
limit range of the number of cluster molecules.
[0030]
Based on the above-mentioned consideration, the cluster of the
Nano sized high-temperature dryness steam M3 generated by the
cluster generating device 6 was specified to be within the range
of several molecules to several tens of molecules. The above
studies were done based on the printing paper that are currently
on the market, so that it is expected that the number of molecules
of the cluster of the Nano sized high-temperature dryness steam
M3 fluctuates depending on the property of the printing papers
that are to be developed in the future. The point is that the
number of molecules of the cluster of the Nano sized
high-temperature dryness steam M3 generated by the cluster
generating device 6 may take any values as long as it is the
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value with which the Nano sized high-temperature dryness steam
M3 can pass through the fiber pores of the printing paper and
can impart intramolecular energy to the ink on the printing
paper by the exciting device 7 to be described later.
5 [0031]
The exciting device 7 utilizes the steam pressure within the
boiler 8 and jets it out from nozzles 25 of the pipe 23 to spray
the high-temperature dryness steam M3 made as a cluster is
generated to the Nano oder onto the print side of the printed
10 paper lb to give the intramolecular energy to the ink 26 of the
printed paper lb by the high-temperature dryness steam M3 (see
FIG. 5A) .
[0032]
Specifically, the exciting device 7 has the Nano sized
15 high-temperature dryness steam M3 made as a cluster is generated
to the Nano oder of several molecules to several tens of
molecules generated by the cluster generating device 6 pass
through the fiber pores of the printed paper lb, and has the
Nano sized high-temperature dryness steam M3 collide with the
ink 26 on the print side to impart the intramolecular energy
to the ink 26 (see FIG. 5A).
[0033)
Ink includes polar molecules. The polar molecule means an
electric dipole whose oxygen side has a minus charge and
hydrogen side has a plus charge, for example. Since the ink
has polar molecules, it has such a property that notable
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temperature increase can be obtained when an energy is applied
from outside compared to a case of having nonpolar molecules.
[0034]
Unlike the normal water molecule cluster, the Nano sized
high-temperature dryness steam NI3 clustered by the cluster
generating device 6 is in a high temperature and in a dry state.
Thus, it is in a state of a high energy (excited state).
[0035]
Therefore, when the exciting device 7 has the Nano sized
high-temperature dryness steam M3 collide with the ink 26 on
the print side, the thermal influence of the Nano sized
high-temperature dryness steam M3 comes to give an energy as
intramolecular vibration 26a to the inside the ink of the print
side (see FIG. 5A).
[0036]
Next, described is a method for drying (f ixing) the ink attached
on the print side of the printed paper lb by using the printed
material drying apparatus A according to the embodiment of the
present invention.
[0037]
First, the steam generating device 5 heats the water with the
heater 15 of the boiler 8 to generate the high-temperature
saturated steam Ml within the boiler 8. When the feeding valve
18 is opened, the steam generating device 5 sends out the
high-temperature saturated steam Ml within the boiler 8 to the
pipe 19 by the steam pressure within the boiler 8. The pipe
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19 is heated by the tubular heater 20, so that the steam supplied
from the pipe 19 becomes the high-temperature dryness steam M2.
[0038]
When the high-temperature dryness steam M2 is supplied to the
pipes 23 and 24 from the steam generating device 5, the cluster
generating device 6 sprays the high-temperature dryness steam
M2 towards the printedpaper lb from the pipes 23, 24 byutilizing
the steam pressure within the boiler 8 so as to generate the
Nano sized high-temperature dryness steam M3 made as a cluster
is generated to the Nano oder.
[0039]
The exciting device 7 utilizes the steam pressure within the
boiler 8 and jets out the Nano sized high-temperature dryness
steam generated by the cluster generating device 6 onto the
print side of the printed paper lb to impart the intramolecular
energy to the ink on the the print side by the Nano sized
high-temperature dryness steam. Specifically, the exciting
device 7 sprays the Nano sized high-temperature dryness steam
M3 to the printed paper lb to have the Nano sized
high-temperature dryness steam M3 pass through the fiber pores
of the printed paper lb and to have the Nano sized
high-temperature dryness steam M3 collide with the ink 26 on
the print side to impart the thermally excited energy of the
Nano sized high-temperature dryness steam M3 as the
intramolecular energy 26a of the ink 26.
[0040]
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Next, the principle of drying (fixing) the ink on the print side
by the Nano sized high-temperature dryness steam M3 will be
described.
[0041]
Conventional ink drying uses hot air of about 200 C, so that
bubbles are generated in the ink. The reason thereof will be
described. As shown in FIG. 5B, only the surface of the ink
26 is dried by receiving the thermal influence of the hot air,
so that a surface stiffening film 26b is formed on the surface
of the ink 26. Further, when heating is progressed, the heat
i s trans f erred (heat conduction) inside theink26and non-dried
regions are bumped up locally, thereby generating bubbles 26c.
In order to avoid this, it is necessary to perform drying of
the ink 26 by reducing the heat capacity and securing the heating
time more than it is necessary in order to equalize the heat
conduction after the surface stiffening film 26b is formed.
Thus, it is not possible to shorten the drying time of the ink.
[0042]
The embodiment of the present invention is designed to
accelerate drying of the ink effectively by using the Nano sized
high-temperature dryness steam. The mechanism thereof is as
follows.
(1) As described above, the Nano sized high-temperature dryness
steam (ultra-fine water drop cluster) is formed with clustered
particles on the order of several molecules to several tens of
molecules, andisformed with high-temperature particles of 150
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- 210 C.
(2) The printing paper as the heating target is made mainly with
paper, ink (water-based, pigments, and aliphatic carbonization
water-solvent such as toluene, xylene, benzene, and the like),
and a coating (pigments paint) material.
(3) Even though there are various kinds as the structure of the
printed papers, the printed papers basically have a pore (gap)
structure in which structural fibers are laminated. Thus, the
printing papers include many apertures microscopically as shown
in FIG. 4A and FIG. 4B.
[0043]
When the exciting device 7 sprays the Nano sized
high-temperature dryness steam M3 clustered on the Nano oder
to the printed paper lb,the Nanosized high-temperature dryness
steam M3 passes through the fiber pores of the printed paper
lb. This is because the clustered molecules of the Nano sized
high-temperature dryness steam M3 are set to be in a size capable
of passing through the fiber pores by considering the diameter
of the fiber pores of the printed paper lb. Therefore, the Nano
sized high-temperature dryness steam M3 that is the particles
of the order of several molecules to several tens of molecules
easily passes through the fiber pores of the printed paper lb,
so that the Nano sized high-temperature dryness steam M3 does
not contribute to heating the printing paper lb. As a result,
the printing paper can maintain the moisture content that is
required in the printing industry.
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[0044]
Further, when the exciting device 7 jets the Nano sized
high-temperature dryness steam M3 clustered on the Nano oder
to the printed paper lb, the Nano sized high-temperature dryness
5 steam M3 collides with the ink 26 that is attached on the print
side of the printed paper lb as shown in FIG. 5A.
[0045]
Unlike the normal.water molecule cluster, the Nano sized
high-temperature dryness steam M3 clustered by the cluster
10 generating device 6 is in a high temperature and in a dry state,
so that it is in a state of a high energy (excited state).
[0046]
Therefore, when the exciting device 7 has the Nano sized
high-temperature dryness steam M3 collide with the ink 26 on
15 the print side, the thermal influence of the Nano sized
high-temperature dryness steam M3 comes to impart the energy
as the intramolecular vibration 26a to the inside the ink 26
of the print side as shown in FIG. 5A. Upon receiving the energy
from the Nano sized high-temperature dryness steam M3,
20 vibration of the water molecules inside the ink 26 becomes more
intense. Thus, the temperature within the ink is increased due
to generation of frictional heat. According to this principle,
drying of the ink 26 is accelerated.
[0047]
With the above-described mechanism, when drying the ink on the
printing paper, the printed paper lb is not heated but only the
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ink 26 thereon absorbs the energy of the Nano sized
high-temperature dryness steam, and generates heat and causes
evaporation. This makes it possible to heat only the ink
selectively.
[0048]
When drying the ink on the printing paper, the Nano sized
high-temperature dryness steam M3 at least easily passes
through the inside the pores (capillaries) of the printing paper
by using the water molecules clustered on the Nano oder
(high-temperature dryness steam cluster on the order of several
molecules to several tens of molecules). Thus, only the ink
absorbs the energy of the Nano sized high-temperature dryness
steam without heating the printing paper, and generates heat
and causes evaporation. Thereby, only the ink can be heated
selectively.
[0049]
FIG. 6 shows schematic charts of drying degree - time passage,
showing influence of the Nano sized high-temperature dryness
steam on drying the ink. FIG. 6b is the chart of drying degree
- time passage according to the conventional ink drying, with
which a lot of time hangs at dry time (tl - t2) , and the quality
of dryness (D1) is also poor.
[0050]
In the meantime, FIG. 6A is the chart of drying degree - time
passage according to the ink drying achieved by the Nano sized
high-temperature dryness steam of the embodiment of the present
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22
invention, with which the time required for drying is almost
instantaneous (ta - tb) , and the quality of dryness (D2) is also
excellent. This is because the conventional ink drying method
as described above dries the ink in a following manner. That
is, the surface layer of the ink is dried by receiving the thermal
influence -. the surface stiffening film is formed- bubbles are
generated heat is transferred into inside the ink. In the
meantime, with the Nano sized high-temperature dryness steam,
heat is generated inside the ink and the ink is dried with the
conductive heat. Therefore, high-quality drying can be
accelerated.
[0051J
In the above, drying of the ink 26 on the printing paper lb by
using the Nano sized high-temperature dryness steam M3 has been
specifically described. However, the present invention is not
limited only to that. That is, the printed material drying
apparatus A according to the embodiment of the present invention
can accelerate the deodorizing effect of a noxious gas 26d
(drying-oil component = unsaturated fatty acid, oil-based
solvent, etc.) generated in the process of drying the ink 26.
Specifically, as shown in FIG. 5A, the noxious gas 26d contained
in the component of the ink 26 is generated in the process of
drying the ink 26. The noxious gas 26d may give off a nasty
smell. This noxious gas 26d is mainly generated in the process
where the printed material lb travels inside the drying chamber
21 . More specifically, the noxious gas 26d may be emitted from
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the drying chamber 21 to the outside in following processes.
(1) In the process where the low boiling point solvent of the
ink is evaporated and dried.
(2) In the process where: oxygen in the air and the drying-oil
component (unsaturated fatty acid) in the ink are combined by
a catalysis caused by a dryer; a chemical change occurs;
polymerization of the drying oil occurs; and the ink is dried.
(3) In the process where the oil-based solvent in the ink is
evaporated and dried by the heat.
When the noxious gas 26d leaks to the work environment outside
the drying chamber 21, not only the work environment is
contaminated but also the residents in the surroundings of the
printing factory is exposed to bad influences.
[0052]
With the embodiment of the present invention, the Nano sized
high-temperature dryness steam M3 is jetted out from the pipes
23, 24 to form an air curtain within the drying chamber 21. In
a space sectioned by the air curtain, the Nano sized
high-temperature dryness steam M3 in ultra-fine particles by
being clustered on the Nano oder collides with the noxious gas
26d that is generated from the ink 26. When the Nano sized
high-temperature dryness steamM3 on the Nano oder collides with
the noxious gas 26d (clustered water drops tend to become
negative ions, and the noxious gas 26d is attached thereto),
the noxious gas 26d is ion-decomposed by the Nano sized
high-temperature dryness steam M3. It is taken into the cluster
CA 02692876 2010-01-07
24
droplets, and collected to a saucer (reference numeral B in FIG.
1) for the cluster droplets.
[0053]
As described above, the embodiment of the present invention can
achieve drying of the printing ink by utilizing the Nano sized
high-temperature dryness steam.
[0054]
Further, by having the Nano sized high-temperature dryness
steam pass through the fiber pores of the printing paper through
setting the cluster molecules of the Nano sized
high-temperature dryness steam to be within a range of several
molecules to several tens of molecules, it is possible to dry
the ink while maintaining the moisture content of the printing
paper required in the printing industry by avoiding to heat the
printing paper.
[0055]
Furthermore, it is possible to heat only the ink on the print
side selectively with the Nano sized high-temperature dryness
steam. Moreover, the intramolecular vibration is generated
inside the ink, so that drying of the ink can be accelerated.
[0056]
Further, the embodiment of the present invention makes it
possible to keep the clean work environment without having the
noxious gas generated from the ink leak to the work environment
due to the combined effect of the chemical bonding of the noxious
gas generated during the ink drying process with negative ions
CA 02692876 2010-01-07
generated by Lenard effect with which a droplet is ionized in
the nearby air when it is dissolved (i.e., deodorizing effect
by the oxidation reaction generated by the collision with the
Nano sized high-temperature dryness steam) and the effect of
5 taking the noxious gas into the cluster droplets. Further, even
when printing is performed in environments where factories and
residential areas are close, the embodiment makes it possible
to avoid contamination of the environment without obstructing
the health of the nearby residents by leaking no noxious gas
10 to the surroundings of the printing factory. As described, the
embodiment can provide the ink drying processing that is also
good for the environments.
[0057]
Next, an investigation was conducted in order to dry the ink
15 by using the printed material drying apparatus according to the
embodiment of the present invention. There has not been any
thesis which academically analyzes the most important factors
for enabling drying of the printing ink by utilizing the Nano
sized high-temperature dryness steam. The inventors of the
20 present invention conducted studies and experiments, and came
to a conclusion that the most important factors for performing
drying of the printing ink are the high-temperature dryness
temperature and the moisture content on the print side of the
printing paper.
25 [0058]
Normally, it is considered in the printing industry that the
CA 02692876 2010-01-07
26
moisture content of the printing paper to which printing has
been done is in a range of S. 5 - 4. 5 0. In a case of performing
drying by using hot air, the moisture content of the printing
paper is decreased. In that case, following issues occur: (1)
generation of static electricity; (2) contraction (distortion)
of the paper surface; (3) swelling (expansion) of the paper
surface; and (4) deterioration in the bending strength.
[0059]
The inventors of the present invention have come to a conclusion
that the use of Nano sized high-temperature drying air can make
it possible to dry the ink without decreasing the moisture
content. Hereinafter, details thereof will be described in
details.
[0060]
A: Relation between Paper Basis Weight and Moisture Content
In the experiment, paper basis weights of 180 g/m2 and 240 g/m2
were used as cut sheet (single paper) . FIG. 7 shows the
relation between the paper surface temperature and the moisture
content in a case where the cut sheet is let through the ink
high-temperature dryer after printing offset ink (off rotary
ink) on the surface.
[0061]
A paper moisture meter K-200 (Manufacturer: KETT) was used for
measuring the moisture content of the printing paper. A pocket
radiometer PC-8400 (Manufacturer: SATO KEIRYOKI MFG. Co., LTD)
was used for measuring the paper surface temperature. The
CA 02692876 2010-01-07
27
sensor was of a thermopile type, and the measurable range was
-60-240 C. The measurement distance between the paper surface
and the sensor was fixed to be about 30 mm.
[0062]
As the result of the experiment, it was found that the surface
temperature is higher with the paper having the smaller basis
weight 180 g/m2 (thin cut sheet) than that of the paper with
the larger basis weight 240 g/m2 (thick cut sheet). Further,
there is a tendency that the moisture content of the basis weight
becomes lower as the paper surface temperature becomes higher.
This is simply considered because the heat can be absorbed
quickly with the paper having the small basis weight (thinner
paper) . This can be lead to the fact that the heat absorption
and heat radiation can be done more quickly when the paper is
of the smaller basis weight. Thereafter, the experiment was
conducted by using the paper having the basis weight of 180 g/m2
by considering the printing on a rolled paper.
[0063]
B: In-Chamber Temperature of Drying Chamber 21 and Moisture
Content of Printed Paper lb
FIG. 8 shows the relation between the in-chamber temperature
and the moisture content of the paper surface. In FIG. 8, the
lateral axis shows the in-chamber temperature. The
temperature was set within a range of 180 - 210 C, and
measurement was conducted at 10 C interval. The longitudinal
axis shows the moisture content on the printing paper surface
CA 02692876 2010-01-07
28
measured at each temperature. The in-chamber temperature
means the temperature of the Nano sized high-temperature
dryness steam within the drying chamber. It was found as a
result that a large difference in drying of the ink by using
the Nano sized high-temperature drying steam is that the paper
surface temperature is not increased, so that contraction and
swelling of the papersurface mentioned above were not observed.
This is in common to the case with a printing paper feeding speed
of 1.8 m/min and a faster feeding speed of 3.6 m/min (180 - 360
cm/min).
[0064]
From this experiment, it was found that the feeding speed of
3 - 3.6 m/min of the printing paper lb within the drying chamber
21 and the in-chamber temperature of about 180 - 190 C were the
optimum in a case where the required printing paper moisture
content is in a range of 8.5 - 7.5%.
[0065]
C: In-Chamber Temperature of Drying Chamber 21 and Surface
Temperature of Printed Paper lb
FIG. 9 shows the relation between the in-chamber temperature
and the paper surface temperature. The in-chamber temperature
was changed in a range of 180 - 210 C. From FIG. 8, it has
already been found that the optimum in-chamber temperature was
about 180 - 190 C. From FIG. 9, the paper surface temperature
when the in-chamber temperature was 180 - 190 C was about 70
- 90 C. Since the paper surface temperature varies according
CA 02692876 2010-01-07
29
to the paper basis weight, those temperatures do not correspond
to all the cases. However, those are considered as adequate
numerical values for the case with the water basis weight of
180 g/m2, and 1.8 - 3.6 m/min.
[0066]
In the meantime, the paper surface temperature increases as the
in-chamber temperature becomes higher. Further, there is
obviously a tendency that the slower the feeding speed is, the
higher the paper surface temperature becomes. Therefore, for
enabling an operation with an increased in-chamber temperature,
the target paper surface temperature can be obtained by
increasing the paper feeding speed.
[0067]
D: Feeding Speed of Printed Paper lb within Drying Chamber 21
and Paper Surface Temperature
FIG. 9 and FIG. 10 show the relation between the paper surface
speed and the paper surface temperature. In order to secure
the feeding speed 1.8 - 3.6 m/min of the printed paper lb and
the paper surface temperature of 70 - 90 C, the in-chamber
temperature of 180 - 190 C is the optimum. It is also clear
from FIG. 9 and FIG. 10 that the paper surface temperature tends
to increase as the in-chamber temperature becomes higher.
[0068]
E: Surface Temperature and Moisture Content of Printing Paper
FIG. 11 shows the relation between the surface temperature of
the printing paper and the moisture content of the paper surface.
CA 02692876 2010-01-07
In order to keep the moisture content of the printing paper
around 7.5 - 9 s, it is important to set the surface temperature
of the printing paper to be in a range of 70 - 90 C and to the
feeding speed of 3 - 3.6 m/min.
5 [0069]
Inversely, the result thereof indicates that it is an important
factor to set the feeding speed as 3.6 m/min or more in order
to have the moisture content of the printing paper to be in a
range of 9 - 10%.
10 [0070]
F: Feeding Speed of Printing Paper and Moisture Content
FIG. 12 shows the relation between the feeding speed and the
moisture content of the paper surface. As in the case of FIG.
11, it is important to set the feeding speed as 3 - 3.6 m/min
15 and to set the in-chamber temperature as 180 - 190 C in order
to suppress the moisture content of the printing paper to 7-
9%
o.
[0071]
That is, when the in-chamber temperature is increased, the
20 moisture content of the printing paper becomes decreased. Thus,
it is important to control the in-chamber temperature.
[0072]
G: Paper Surface Temperature of Printing Paper Affected by
Distance between Printing Paper and Nozzle 25 of Pipe 23 Placed
25 above Printing Paper
In order to investigate the paper surface temperature affected
CA 02692876 2010-01-07
31
by the distance between the nozzle 25 and the printed paper lb,
the nozzle height from the paper surface is plotted on the
lateral axis. The height of the nozzle 25 from the paper surface
of the printed paper lb was set to a range of 25 - 65 mm. The
longitudinal axis shows the surface temperature or the moisture
content of the printing paper surface measured at each
temperature. FIG. 13 shows the inf luence on the paper surface
temperature affected by the distance between the nozzle and the
paper surface.
[0073]
When the distance between the nozzle and the paper surface was
brought closer to be 25 mm, the surface temperature of the paper
was increased. Inversely, when the distance is set away to be
65 mm, there was a tendency of reduction in the surface
temperature of the paper. This is considered because the
dryness steam temperature is higher when the paper surface is
closer to the nozzle, so that the printing paper is exposed to
high temperatures.
[0074]
In the meantime, as shown in FIG. 14, the moisture content tends
to increase. This is intimately related to the temperature of
the Nano sized high-temperature dryness steam shown in FIG. 13,
and it indicates that the moisturized printing can be done by
keeping a specific distance between the nozzle and the paper
surface.
[0075]
CA 02692876 2010-01-07
32
H: Ink Attaching Degree Affected by In-Chamber Temperature of
Drying Chamber 21 and Feeding Speed of Printing Paper
In order to perform quantitative evaluation of the drying degree
of the ink, "tape putting method" was employed. With this
method, the area ratio of the ink residual was obtained by image
processing through a following procedure.
(1) Cellophane adhesive tape was put on the print side.
(2) Scanning was conducted from 600 dpi by using a scanner
function of a copying machine (RICOH imagio Neo c285).
(3) Trimming processing was conducted by adobe photoshop 6 to
perform binarization with a threshold value 255.
(4) Thereafter, the area ratio was obtained by using image
software.
FIG. 15 shows examples of the in-chamber temperatures and the
ink attaching degrees (average) . Simply, when there are more
black dots, it means that the ink is un-dried. Thus, black dots
(ink) are transferred to the cellophane adhesive tape side.
[0076]
FIG. 16 shows the relation between the in-chamber temperature
and area ratio obtained from the ink attaching degree (binarized
by the image processing) by using the tape putting method, and
FIG. 17 shows the relation between the ink attaching degree and
the feeding speed.
[0077]
From the results of those, it was found that the proper
temperature for achieving low ink attaching degree was 200 C.
CA 02692876 2010-01-07
33
For the feeding speed of the printing paper, the ink attaching
degree was low and excellent performance was observed at the
lowest speed of 2.4 - 3.0 m/min.
[0078]
The reason the ink attaching degree was worsened with the 210 C
high-temperature dryness steam was that a bumping phenomenon
occurred in the rotary ink when the temperature thereof exceeds
200 C. Thus, in normal printing, it is cooled down by a cooling
cylinder to accelerate solidification (fixation) of the ink.
However, the case of the apparatus of the present invention did
not use the cooling cylinder, so that it is considered that ink
was fluidized in that case.
[0079]
As evident from the results of the above-described experiments,
it has been proved that acceleration of drying the ink on the
printing paper by using the Nano sized high-temperature dryness
steam clustered on the Nano oder as in the embodiment of the
present invention is fully practical_
INDUSTRIAL APPLICABILITY
[0080]
The present invention is capable of drying the ink of the printed
material by using the Nano sized high-temperature dryness steam
while keeping the moisture retention in the printing paper.
BRIEF DESCRIPTION OF THE DRAWINGS
[0081]
FIG. 1 is a block diagram showing an example of a printing
CA 02692876 2010-01-07
34
device to which a printed material drying apparatus according
to an embodiment of the present invention is applied;
FIG. 2 is a perspective view showing a cluster generating
device and an exciting device in the printed material drying
apparatus according to the embodiment of the present invention;
FIG. 3 is an illustration showing the relation regarding
a steam generating device, the cluster generating device, and
the exciting device in the printed material drying apparatus
according to the embodiment of the present invention;
FIG. 4 shows photographs of f iber pores of a printing paper
observed by a scanning electron microscope;
FIG. 5A is an illustration showing the principle of drying
the ink by the printed material drying apparatus according to
the embodiment of the present invention, and FIG. 5B is an
illustration showing the principle of drying the ink according
to a conventional case;
FIG. 6A is a characteristic chart showing the ink drying
degree achieved by the printed material drying apparatus
according to the embodiment of the present invention, and FIG.
6B is a characteristic chart showing the ink drying degree of
a ink drying method according to the conventional case;
FIG. 7 is a chart showing the surface temperature and the
moisture content of a printing paper in a cut sheet;
FIG. 8 is a chart showing the relation between the
in-chamber set temperature and the moisture content of the
printing paper in a cut sheet;
CA 02692876 2010-01-07
FIG. 9 is a chart showing the relation between the
in-chamber set temperature and the paper surface temperature
of the printing paper in a cut sheet;
FIG. 10 is a chart showing the relation between the feeding
5 speed of the printing paper and the paper surface temperature
of the printing paper in a cut sheet;
FIG. 11 is a chart showing the relation between the paper
surface temperature and the moisture content of the printing
paper in a cut sheet;
10 FIG. 12 is a chart showing the relation between the feeding
speed of the printing paper and the moisture content of a
printing paper in a cut sheet;
FIG. 13 is a chart showing the surface temperature of the
printing paper affected by the distance between a nozzle and
15 the printing paper;
FIG. 14 is a chart showing the moisture content of the
printing paper affected by the distance between the nozzle and
the printing paper;
FIG. 15 is an illustration showing the ink attaching
20 degree when using an adhesive tape putting method;
FIG. 16 is a chart showing the relation between the
in-chamber temperature and the ink attaching degree of the
printing paper in a cut sheet; and
FIG. 17 is a chart showing the relation between the feeding
25 speed of the printing paper and the ink attaching degree of the
printing paper in a cut sheet.
CA 02692876 2010-01-07
36
REFERENCE NUMERALS
[0082] 5 Steam generating device
6 Cluster generating device
7 Exciting device
