U.S. patent application number 11/223951 was filed with the patent office on 2006-04-27 for method and apparatus for conditioning moisture of object to be moisture conditioned.
This patent application is currently assigned to FUJI PHOTO FILM CO., LTD.. Invention is credited to Manabu Hashigaya, Kenji Hayashi.
Application Number | 20060086109 11/223951 |
Document ID | / |
Family ID | 35414620 |
Filed Date | 2006-04-27 |
United States Patent
Application |
20060086109 |
Kind Code |
A1 |
Hayashi; Kenji ; et
al. |
April 27, 2006 |
Method and apparatus for conditioning moisture of object to be
moisture conditioned
Abstract
There are provided a moisture conditioning method and a moisture
conditioning apparatus which enable the moisturizing of a coating
film in a short time and at high efficiency, thereby improving
productivity, and besides, do not require an increase in the path
length of the moisture conditioning zone, thereby contributing to
cost saving and space saving. When moisture conditioning a coating
film having been applied onto a substrate by allowing the coating
film to stand in or pass through a moisture conditioning zone where
humidity is controlled by spraying water, the water to be sprayed
in the moisture conditioning zone is made into fine water particles
before being sprayed by applying a high voltage or a magnetic force
to the water using a moisture conditioning apparatus.
Inventors: |
Hayashi; Kenji;
(Haibara-gun, JP) ; Hashigaya; Manabu;
(Haibara-gun, JP) |
Correspondence
Address: |
SUGHRUE MION, PLLC
2100 PENNSYLVANIA AVENUE, N.W.
SUITE 800
WASHINGTON
DC
20037
US
|
Assignee: |
FUJI PHOTO FILM CO., LTD.
|
Family ID: |
35414620 |
Appl. No.: |
11/223951 |
Filed: |
September 13, 2005 |
Current U.S.
Class: |
62/171 |
Current CPC
Class: |
G03F 7/168 20130101 |
Class at
Publication: |
062/171 |
International
Class: |
F28D 3/00 20060101
F28D003/00 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 13, 2004 |
JP |
2004-265426 |
Claims
1. A method for conditioning the moisture of an object to be
moisture conditioned by allowing the object to be moisture
conditioned to stand in or pass through a moisture conditioning
zone where humidity is controlled by spraying water, comprising the
steps of: making the water to be sprayed into fine water particles;
and spraying the water made into fine water particles in the
moisture conditioning zone.
2. The moisture conditioning method according to claim 1, wherein
the water having been made into fine water particles has a particle
size of 2.0 .mu.m or less.
3. A method for conditioning the moisture of an object to be
moisture conditioned by allowing the object to be moisture
conditioned to stand in or pass through a moisture conditioning
zone where humidity is controlled by spraying water, comprising the
steps of: charging the water to be sprayed positively or
negatively; and charging the object to be moisture conditioned
opposite to the water to be sprayed or making to have a potential
of 0 (being grounded).
4. The moisture conditioning method according to claim 3, wherein
the water is made into fine water particles at the time of or
before being charged.
5. The moisture conditioning method according to claim 1, wherein
the water is made into fine water particles by applying a voltage
as high as 1000 V to 20000 V to the water.
6. The moisture conditioning method according to claim 2, wherein
the water is made into fine water particles by applying a voltage
as high as 1000 V to 20000 V to the water.
7. The moisture conditioning method according to claim 4, wherein
the water is made into fine water particles by applying a voltage
as high as 1000 V to 20000 V to the water.
8. The moisture conditioning method according to claim 1, wherein
the water is made into fine water particles by applying a magnetic
force of 500 Gauss or more to the water.
9. The moisture conditioning method according to claim 2, wherein
the water is made into fine water particles by applying a magnetic
force of 500 Gauss or more to the water.
10. The moisture conditioning method according to claim 4, wherein
the water is made into fine water particles by applying a magnetic
force of 500 Gauss or more to the water.
11. The moisture conditioning method according to claim 1, wherein
the object to be moisture conditioned is an overcoat layer
containing PVA as a main component, which is applied onto a
photosensitive layer in the production of a photopolymerizable
lithographic plate.
12. The moisture conditioning method according to claim 2, wherein
the object to be moisture conditioned is an overcoat layer
containing PVA as a main component, which is applied onto a
photosensitive layer in the production of a photopolymerizable
lithographic plate.
13. The moisture conditioning method according to claim 3, wherein
the object to be moisture conditioned is an overcoat layer
containing PVA as a main component, which is applied onto a
photosensitive layer in the production of a photopolymerizable
lithographic plate.
14. The moisture conditioning method according to claim 4, wherein
the object to be moisture conditioned is an overcoat layer
containing PVA as a main component, which is applied onto a
photosensitive layer in the production of a photopolymerizable
lithographic plate.
15. The moisture conditioning method according to claim 5, wherein
the object to be moisture conditioned is an overcoat layer
containing PVA as a main component, which is applied onto a
photosensitive layer in the production of a photopolymerizable
lithographic plate.
16. The moisture conditioning method according to claim 8, wherein
the object to be moisture conditioned is an overcoat layer
containing PVA as a main component, which is applied onto a
photosensitive layer in the production of a photopolymerizable
lithographic plate.
17. An apparatus for conditioning the moisture of an object to be
moisture conditioned by allowing the object to be moisture
conditioned to stand in or pass through a moisture conditioning
zone where humidity is controlled by spraying water, comprising: a
spraying device which sprays water in the moisture conditioning
zone; and a fine water particle-forming device which makes the
water to be sprayed into fine water particles.
18. The moisture conditioning apparatus according to claim 17,
wherein the fine water particle-forming device is a high-voltage
applying device which applies a high voltage to the water in the
form of a mist which has been sprayed by the spraying device.
19. The moisture conditioning apparatus according to claim 17,
wherein the fine water particle-forming device is a magnetic force
applying device which applies a magnetic force to the water fed to
the spraying device.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a method and an apparatus
for conditioning the moisture of an object to be moisture
conditioned, in particular, to a technique for conditioning the
moisture of an overcoat layer, which has been applied onto a
photopolymerizable layer (photosensitive layer) when producing a
photopolymerizable lithographic plate.
[0003] 2. Related Art
[0004] In the production of a photopolymerizable lithographic plate
that includes an overcoat layer containing, as a main component, a
water-soluble polymer having hydrogen bonding groups, improving
sensitivity is a key factor, and thus, there have been conducted
research and development of a number of photosensitive systems
utilizing radical polymerization, which is advantageous in
improving sensitivity. However, since radical polymerization
systems are susceptible to polymerization inhibition by oxygen,
devices have been thought out to increase the polymerization
efficiency. For example, an overcoat layer containing polyvinyl
alcohol (PVA), as a main component, and having excellent oxygen
barrier properties is provided onto the photopolymerizable layer.
In this overcoat layer, if its oxygen permeating rate is too high,
the resultant photopolymerizable lithographic plate has a lower
sensitivity, whereas if the oxygen permeating layer is too low, the
resultant photopolymerizable lithographic plate has an abnormally
increased sensitivity, which may undesirably result in poor
development, stains or residual film. The oxygen barrier properties
of the overcoat layer are largely affected by the moisture content
of the same, and thus, it is important to control the moisture
content properly. The moisture content of the overcoat layer is
controlled by first applying the overcoat layer onto a
photopolymerizable layer and then allowing the overcoat layer
having been applied onto the photopolymerizable layer to stand in
or pass through a constant-temperature/constant-humidity moisture
conditioning zone.
[0005] However, when moisture conditioning the overcoat layer
having been applied onto a belt-like substrate by allowing the same
to pass through a moisture conditioning zone while continuously
conveying the belt-like substrate, the amount of moisture fed to
the overcoat layer depends on the temperature/humidity conditions
of the moisture conditioning zone and the residence time of the
substrate in the moisture conditioning zone. Accordingly, when
increasing the substrate-conveying speed aiming at a productivity
increase, it is necessary to enhance the moisture-conditioning
performance of the moisture conditioning zone by, for example,
increasing the path length of the moisture conditioning zone.
However, if there is no space for increasing the moisture
conditioning zone, the above measure cannot be adopted. Thus, to
increase the substrate conveying speed while avoiding increasing
the path length of the moisture conditioning zone, a technique is
required which enables the moisturizing of the overcoat layer in a
short time and at high efficiency. The same is true for the case
where moisture conditioning of an object to be moisture conditioned
is performed by allowing the object to be moisture conditioned to
stand in a moisture conditioning zone.
[0006] Conventional techniques for moisturizing an object to be
moisture conditioned include, for example, those disclosed in
Japanese Patent Application Laid-Open Nos. 6-257093, 2000-42030,
2003-145650 and 2000-264664. Japanese Patent Application Laid-Open
No. 6-257093 discloses a technique for moisture conditioning paper
in which the moisture conditioning is carried out by water
application and heating. Japanese Patent Application Laid-Open No.
2000-42030 discloses a technique in which moisture conditioning is
carried out by making water into fine water particles using
ultrasonic wave. Japanese Patent Application Laid-Open No.
2003-145650 discloses a technique for moisture conditioning
corrugated board sheets in which moisture conditioning is carried
out by controlling the amount of heating. And Japanese Patent
Application Laid-Open No. 2000-264464 discloses a technique for
moisturizing sheets.
SUMMARY OF THE INVENTION
[0007] Although the above described techniques, which are disclosed
in Japanese Patent Application Laid-Open Nos. 6-257093, 2000-42030,
2003-145650 and 2000-264664, are typical techniques for moisture
controlling an object to be moisture controlled, they are not
satisfactory ones in terms of moisturizing an object to be moisture
conditioned in a short time and at high efficiency.
[0008] So far, problems with moisture conditioning techniques have
been described taking the case of the overcoat layer of a
photopolymerizable lithographic plate; however, the application of
the moisture conditioning method or apparatus of the present
invention is not intended to be limited to such an overcoat layer.
The same problems also arise in moisture conditioning of paper
(e.g. corrugated board), resin film and the like, and the present
invention is also applicable when an object to be moisture
conditioned is paper, resin film or the like.
[0009] The present invention has been made in the light of the
above described situation. Accordingly, the object of the present
invention is to provide a moisture conditioning method and
apparatus for moisture conditioning an object to be moisture
conditioned which enable the moisturizing of the object in a short
time and at high efficiency, thereby realizing a productivity
increase, and besides, which does not require an increase in the
path length of a moisture conditioning zone, whereby contributing
to cost saving as well as space saving.
[0010] To accomplish the above described object, a first aspect of
the present invention is a method for conditioning the moisture of
an object to be moisture conditioned by allowing the object to be
moisture conditioned to stand in or pass through a moisture
conditioning zone where humidity is controlled by spraying water,
comprising the steps of: making the water to be sprayed into fine
water particles, and spraying the water made into fine water
particles in the moisture conditioning zone.
[0011] According to the first aspect of the present invention, the
water to be sprayed in the moisture conditioning zone penetrates
into the object to be moisture conditioned more easily because it
is in the form of fine water particles, thereby being capable of
moisturizing the object to be moisture conditioned in a short time
and at high efficiency. This makes it possible not only to increase
productivity, but also to avoid increasing the path length of the
moisture conditioning zone, thereby contributing to cost saving as
well as space saving. The moisture conditioning zone can be not
only moisture conditioned, but also temperature conditioned.
[0012] A second aspect of the present invention is the moisture
conditioning method according to the first aspect of the present
invention, wherein the water having been made into fine water
particles has a particle size of 2.0 .mu.m or less. Making the
water to be sprayed into fine water particles having a particle
size of 2.0 .mu.m or less makes it much easier for the water to
penetrate into the object to be moisture conditioned.
[0013] To accomplish the above described object, a third aspect of
the present invention is a method for conditioning the moisture of
an object to be moisture conditioned by allowing the object to be
moisture conditioned to stand in or pass through a moisture
conditioning zone where humidity is controlled by spraying water,
comprising the steps of charging the water to be sprayed positively
or negatively, charging the object to be moisture conditioned
opposite to the water to be sprayed or making to have a potential
of 0 (being grounded).
[0014] According to the third aspect of the present invention,
since the water to be sprayed and the object to be moisture
conditioned are charged opposite to each other, the water to be
sprayed is attracted to the object to be moisture conditioned,
which makes it possible to moisture the object to be moisture
conditioned in a short time and at high efficiency. In this case,
the object to be moisture conditioned is allowed to have a
potential of 0 (be grounded). Charging the water to be sprayed and
the object to be moisture conditioned in reverse enables a
productivity increase, and at the same time, contributes to cost
saving as well as space saving because to do so does not require
increase in the path length of the moisture conditioning zone. For
example, a negatively charged water mist is formed in such a manner
as to charge the space, where water is to be sprayed, negatively by
applying a high voltage to the air or utilizing Lenard's effect and
spray water in the space. Applying a high voltage to water allows
the water not only to be charged, but also to be made into an ultra
fine mist. On the other hand, the object to be moisture conditioned
is charged positively using corona discharge equipment etc. Thus,
the attraction effect, which is produced by charging the water to
be sprayed and the object to be moisture conditioned, coupled with
the penetration effect, which is produced by making the water to be
sprayed into fine water particles, makes it possible to moisturize
the object to be moisture conditioned in a much shorter time and at
much higher efficiency.
[0015] A fourth aspect of the present invention is the moisture
conditioning method according to the third aspect of the present
invention, wherein the above described water is made into fine
water particles at the time of or before being charged.
[0016] A fifth aspect of the present invention is the moisture
conditioning method according to the first, second or fourth aspect
of the present invention, wherein the above described water is made
into fine water particles by applying a voltage as high as 1000 V
to 20000 V to the water. The fifth aspect of the present invention
is one example of methods for making water into fine water
particles in which a voltage as high as 1000 V to 20000 V is
applied to the water.
[0017] A sixth aspect of the present invention is the moisture
conditioning method according to the first, second or fourth aspect
of the present invention, wherein the above described water is made
into fine water particles by applying a magnetic force of 500 Gauss
or more to the water. The sixth aspect of the present invention is
one example of methods for making water into fine water particles
in which a magnetic force of 500 Gauss (0.05 millitesla) or more is
applied to the water. The application of such a magnetic force
makes it possible to break the clusters of water, thereby making
the water into fine water particles.
[0018] A seventh aspect of the present invention is the moisture
conditioning method according to any one of the first to sixth
aspects of the present invention, wherein the above described
object to be moisture conditioned is an overcoat layer containing
PVA as a main component which is applied onto a photosensitive
material when producing a photopolymerizable lithographic plate.
When the object to be moisture conditioned is an overcoat layer
containing PVA, as a main component, which is applied onto a
photosensitive material when producing a photopolymerizable
lithographic plate, the present invention works very effectively as
a technique for moisture conditioning the overcoat layer to a given
moisture content in a short time.
[0019] To accomplish the above described object, an eighth aspect
of the present invention is an apparatus for conditioning the
moisture of an object to be moisture conditioned by allowing the
object to be moisture conditioned to stand in or pass through a
moisture conditioning zone where humidity is controlled by spraying
water, wherein the apparatus comprises a spraying device which
sprays water in the above described moisture conditioning zone and
a fine water particle-forming device which makes the water to be
sprayed into fine water particles.
[0020] The eighth aspect of the present invention is an apparatus
which makes the water to be sprayed in the moisture conditioning
zone into fine water particles, thereby making it easy for the
water to be sprayed to penetrate into the object to be moisture
conditioned, and hence making it possible to moisturize the object
to be moisture conditioned in a short time and at high
efficiency.
[0021] A ninth aspect of the present invention is the moisture
conditioning apparatus according to the eighth aspect,
characterized in that the above described fine water
particle-forming device is a high-voltage applying device which
applies a high voltage to the water in the form of a mist which has
been sprayed by the above described spraying device.
[0022] The ninth aspect of the present invention is the apparatus
which makes the water to be sprayed into fine water particles,
wherein preferably the voltage applied to the water is as high as
1000 V to 20000 V.
[0023] A tenth aspect of the present invention is the moisture
conditioning apparatus according to the eighth aspect,
characterized in that the above described fine water
particle-forming device is a magnetic force applying device which
applies a magnetic force to the water fed to the above described
spraying device.
[0024] The tenth aspect of the present invention is the apparatus
which makes the water before sprayed into fine water particles with
a magnetic force applying device, wherein preferably the magnetic
force applied to the water is 500 Gauss (0.05 millitesla) or
more.
[0025] The moisture conditioning method and apparatus for moisture
conditioning an object to be moisture conditioned of the present
invention enables the moisturizing of an object to be moisture
conditioned in a short time and at high efficiency, thereby
realizing a productivity increasing, and at the same time, the
method and apparatus do not require increasing of the path length
of the moisture conditioning zone, thereby contributing to cost
saving as well as space saving.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] FIG. 1 is a production line of a lithographic plate raw
material in which the moisture conditioning apparatus for moisture
conditioning an object to be moisture conditioned of the present
invention is incorporated in its moisture conditioning zone;
[0027] FIG. 2 is a schematic diagram of a high voltage-type
moisture conditioning apparatus provided in the moisture
conditioning zone;
[0028] FIG. 3 is a schematic diagram of a magnetization-type
moisture conditioning apparatus provided in the moisture
conditioning zone;
[0029] FIG. 4 is a schematic diagram of a charging-type moisture
conditioning apparatus provided in the moisture conditioning zone;
and
[0030] FIG. 5 is a graph for comparing the moisturizing rates in
the moisture conditioning zones provided with moisture conditioning
apparatuses of the present invention and the moisturizing rate in a
conventional heating/moisturizing zone.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0031] In the following, preferred embodiments of the moisture
conditioning method and apparatus, of the present invention, for
moisture conditioning an object to be moisture conditioned will be
described in detail with reference to the accompanying
drawings.
[0032] FIG. 1 is a view showing one example of production lines 10
of lithographic plate raw materials which include a moisture
conditioning zone incorporating a moisture conditioning apparatus,
of the present invention, for moisture conditioning an object to be
moisture conditioned. Hereafter, preferred embodiments of the
present invention will be described in terms of the production line
10; however, it is to be understood that this is not intended to
limit the application of the present invention to the production
line 10 of lithographic plate raw materials. The present invention
is applicable to all the lines, such as moisturizing lines for
production of corrugated board or production of resin films, in
which a technique for moisture conditioning an object to be
moisture conditioned in a short time and at high efficiency is
needed.
[0033] As shown in FIG. 1, a continuous substrate 14 wound in a
roll is set in a delivery machine 12. The substrate 14 continuously
delivered from the delivery machine 12 undergoes surface treatment
in a surface-treatment section 16. On the back side of the
substrate 14 having been surface treated is formed a back coat
layer in a back coat layer-application/drying section 18 and then
on the front side of the substrate 14 is formed an undercoat layer
in a sub-coat application/drying section 20. Then, on the undercoat
layer are formed a photosensitive layer of a phoptopolymerizable
composition in a photosensitive layer application/drying section 22
and a overcoat layer containing a water-soluble polymer having
hydrogen bonding groups, e.g. PVA (polyvinyl alcohol), as a main
component (PVA coating film) in a overcoat layer application/drying
section 24 in this order, and at the same time, the crystallinity
of the water-soluble polymer contained in the overcoat layer is
controlled to fall in a give range. Then, the moisture content of
the overcoat layer is controlled to fall in a given range, e.g. in
the range of 4 to 8%, in a moisture conditioning zone 26. The
moisture content of the overcoat layer undergoes on-line
measurement with a moisture analyzer 31, and an air conditioning
unit 32 in the moisture conditioning zone 26 controls the
temperature/humidity of the overcoat layer moisture conditioning
zone so that the moisture content data become constant. Thus, the
raw material 14A for a photopolymerizable lithographic plate is
produced, and the produced raw material 14A is wound into a wind-up
machine 28.
[0034] For the substrate 14 used in the present invention,
aluminum, which is dimensionally stable, or an alloy thereof (e.g.
its alloy with silicon, copper, manganese, magnesium, chromium,
zinc, lead, bismuth or nickel) can be used. Usually, conventionally
known materials described in Handbook of Aluminum, 4.sup.th ed.
(Japan Light Metal Association, 1990), such as materials of JIS A
1050, JIS A 1100, JIS A 3103, JIS A 3004, JIS A 3005 and the alloys
thereof in which 0.1 wt % or more of magnesium is added to increase
the tensile strength, can be used.
[0035] For example, when the substrate 14 is an aluminum sheet,
usually the aluminum sheet undergoes various types of surface
treatment in the surface-treatment section 16, depending on the
purpose for which it is used. In a commonly used treatment process,
first the surface of the aluminum sheet is cleaned by subjecting
the aluminum sheet to degreasing or electropolishing and to
desmutting. Then, the aluminum sheet is subjected to mechanical
roughening or/and electrochemical roughening to provide the surface
with fine irregularities. In some cases, chemical etching and
desmutting can sometimes be added when providing the surface with a
fine texture. After that, the surface of the aluminum sheet is
anodized to increase its abrasion resistance and, if necessary, it
undergoes hydrophilization or/and sealing.
[0036] In the back coat layer application/drying section 18, the
back side of the substrate 14 is provided, depending on the
situation, with a coating layer (back coat layer) composed of
organic polymer which is for preventing the photosensitive
composition layer from being scratched when more than one substrate
are stacked one over the other.
[0037] In the sub-coat application/drying section 20, the front
side of the substrate 14 is coated, depending on the situation,
with a coating fluid for an undercoat layer and dried to form an
undercoat layer on its surface. As the coating process and
conditions in the sub-coat application/drying section 20, the
coating process and many of the conditions employed in the
application of photosensitive composition layer described later can
be used.
[0038] In the photosensitive layer application/drying section 22, a
coating of a photopolymerizable photosensitive composition is
applied onto the undercoat layer and dried to form a photosensitive
layer. And in the overcoat layer application/drying section 24, a
coating for an overcoat layer is applied onto the photosensitive
layer.
[0039] FIG. 2 is a schematic diagram of a moisture conditioning
apparatus 34 provided in the moisture conditioning zone 26, which
is one example of high voltage-type apparatus which apply a high
voltage to the water to be sprayed in the moisture conditioning
zone 26 to make the water into fine water particles, thereby
accelerating the moisturizing of the overcoat layer.
[0040] As shown in FIG. 2, the moisture conditioning zone 26 is
enclosed with a tunnel-like casing in which an inlet and an out let
for the substrate 14, which is continuously conveyed in the
direction shown by the arrow in the figure, are formed. The
substrate 14 is conveyed on the pass rollers 38 with its overcoat
layer 14a facing up. The high voltage-type moisture conditioning
apparatus 34 is made up mainly of: a high voltage applying device
consisting of a grounding electrode 40 and a high-voltage electrode
42; mist generating equipment 44; and water feeding equipment 46.
Specifically, the grounding electrode 40 formed in a ring is
arranged above the overcoat layer 14a in parallel with the
substrate 14 and the high-voltage electrode 42 connected to a
high-voltage power supply 47 is arranged above the grounding
electrode 40. The grounding electrode 40 can take the form of a
square, circle, ellipsoid or triangle, instead of a ring. The mist
generating equipment 44 is arranged so that its spraying portion
44A can spray water in the space between the high-voltage electrode
42 and the grounding electrode 40 and is connected to the water
feeding equipment 46. Thus, the water to be sprayed from the
spraying portion 44A passes through a high-voltage electric field
formed between the high-voltage electrode 42 and the grounding
electrode 40, thereby deriving a large amount of energy from the
electric field. When the amount of energy goes beyond the surface
tension of the water, the cluster of water is broken and the water
having been made into fine water particles reaches the overcoat
layer 14a. From the viewpoint of accelerating the breakage of the
water cluster, preferably a voltage as high as 1000 V to 20000 V is
applied to the water and more preferably a voltage as high as 5000
V to 20000 V. The distance (H) between the high-voltage electrode
42 and the grounding electrode 40 is preferably in the range of 100
to 300 mm and more preferably in the range of 150 to 250 mm. And
the particle size of the water having been made into fine water
particles is preferably 2.0 .mu.m or less.
[0041] On the downstream of the moisture conditioning apparatus 34
relative to the direction in which the substrate is conveyed, a
moisture analyzer 31 which measures the moisture of the overcoat
layer 14a in a non-contact manner is arranged, and the moisture of
the overcoat layer 14a having been moisture conditioned in the
moisture conditioning zone 26 is determined.
[0042] FIG. 3 is a schematic diagram of another moisture
conditioning apparatus 50 provided in the moisture conditioning
zone 26, which is one example of magnetization-type apparatus which
apply a magnetic force to the water to be sprayed in the moisture
conditioning zone 26 to make the water into fine water particles,
thereby accelerating the moisturizing of the overcoat layer. The
same equipment and members as those in FIG. 2 will be described
using the same reference numerals.
[0043] As shown in FIG. 3, the casing 36 which encloses the
moisture conditioning zone 26 is the same as that of FIG. 2. The
magnetization-type moisture conditioning apparatus 50 is made up
mainly of: mist generating equipment 44; magnetized water
generating equipment 52 as a magnetic force applying device; and
water feeding equipment 46. Specifically, the spraying portion 44A
of the mist generating equipment 44 is provided above the overcoat
layer 14a and the mist generating equipment 44 is connected to the
water feeding equipment via piping 54. On the midway of the piping
54 is provided magnetized water generating equipment 52. The
magnetized water generating equipment 52 generates a strong
magnetic field in the piping 54 using the N pole and the S pole
arranged so as to face each other across the piping 54. The water
flowing through the piping 54 goes across the magnetic field and is
provided with a magnetic force, whereby the cluster of the water is
broken and the water is made into fine water particles. Preferably,
the particle size of the water having been made into fine water
particles is 2.0 .mu.m or less. Thus, the water having been made
into fine water particles is sprayed from the spraying portion 44A
of the mist generating equipment 44 and reaches the overcoat layer
14a. From the viewpoint of accelerating the breakage of the water
cluster, preferably a magnetic field as strong as 500 Gauss (0.05
millitesla) or more is applied to the water and more preferably a
magnetic field as strong as 800 Gauss (0.08 millitesla).
[0044] In FIG. 3 like in FIG. 2, on the downstream of the moisture
conditioning apparatus 50 relative to the direction in which the
substrate is conveyed, a moisture analyzer 31 which measures the
moisture of the overcoat layer 14a in a non-contact manner is
arranged, and the moisture of the overcoat layer 14a having been
moisture conditioned in the moisture conditioning zone 26 is
determined.
[0045] FIG. 4 is a schematic diagram of a moisture conditioning
apparatus 60 which charges the water to be sprayed in the moisture
conditioning zone 26 negatively while charging the overcoat layer
positively. The apparatus is one example of charging-type moisture
conditioning apparatus which is capable of charging water while
making the water into fine water particles. The same equipment and
members as those in FIG. 2 or FIG. 3 will be described using the
same reference numerals. When the water is charged negatively, the
overcoat layer may be charged positively or have a potential of 0
(be grounded).
[0046] As shown in FIG. 4, the casing 36 which encloses the
moisture conditioning zone 26 is the same as that of FIG. 2. The
charging-type moisture conditioning apparatus 60 is made up mainly
of: a positively charging device 62 which charges the overcoat
layer before entering the moisture conditioning zone 26 positively;
and a negatively charging device which charges the water to be
sprayed in the moisture conditioning zone 26 negatively. As the
positively charging device, for example, corona discharge equipment
is employed. As the negatively charging device, the moisture
conditioning apparatus 34 can be used as it is. Specifically, the
water to be sprayed in the moisture conditioning zone 26 can be
made into fine water particles, while charging the mist consisting
of the fine water particles negatively, by first applying a high
voltage across the high-voltage electrode 42 and the grounding
electrode 40 to charge the space between the high-voltage electrode
42 and the grounding electrode 40 negatively and then spraying
water in the moisture conditioning zone from the mist generating
equipment 44. As a result, the water to be sprayed from the mist
generating equipment 44, which is in the form of fine water
particles and has been charged negatively, is attracted to the
overcoat layer 14a, which has been charged positively, whereby the
moisturizing of the overcoat layer 14a is accelerated. Thus, due to
the attraction effect, which is produced by charging the water to
be sprayed and the overcoat layer 14a oppositely, coupled with the
penetration effect, which is produced by making the water into fine
water particles, the moisture conditioning apparatus 60 of FIG. 4
enables the moisturizing of the overcoat layer 14a in a much
shorter time and at much higher efficiency. So far, this embodiment
has been described taking the case where the moisture conditioning
apparatus 60 charges the overcoat layer 14a positively, while
charging the water negatively; however, the moisture conditioning
apparatus 60 may charge the overcoat layer 14a negatively, while
charging the water positively.
[0047] In FIG. 4 like in FIGS. 2 and 3, on the downstream of the
moisture conditioning apparatus 60 relative to the direction in
which the substrate is conveyed, a moisture analyzer 31 which
measures the moisture of the overcoat layer 14a in a non-contact
manner is arranged, and the moisture of the overcoat layer 14a
having been moisture conditioned in the moisture conditioning zone
26 is determined.
[0048] Each of the moisture conditioning apparatus 34, 50 and 60 of
FIGS. 2 to 4 has been described taking the case where there is only
one moisture conditioning apparatus 34, 50 or 60 in the moisture
conditioning zone 26; however, more than one moisture conditioning
apparatus 34, 50 or 60 may be provided in the moisture conditioning
zone 26, depending on the path length of the moisture conditioning
zone 26.
EXAMPLES
[0049] A PVA coating fluid (a coating fluid containing polyvinyl
alcohol as a main component) was applied onto aluminum substrates
14 so that the amount of the coating fluid applied was 2 g/m.sup.2
to form a PVA coating film (corresponding to the overcoat layer) on
the substrates. Each of the substrates with a PVA coating film
formed on it was allowed to pass through a moisture conditioning
zone 26 in which a high voltage-type, magnetization-type, or
charging-type moisture condition apparatus 34, 50 or 60 was
provided so that the rates of moisturizing the PVA coating film in
the respective cases were compared. The rates of moisturizing the
PVA coating film were determined by measuring the moisture content
of the PVA coating film vs. the residence time of the substrates in
the moisture conditioning zone 26. As the moisture analyzer 31, an
infrared moisture analyzer IRM-V manufactured by CHINO CORPORATION
was used. In comparative examples, water was sprayed in the
moisture conditioning zone 26 by conventional heating/moistening
method.
Comparative Example
[0050] Water heated to 60 to 70.degree. C. was sprayed in the
moisture conditioning zone 26 with a fan.
Example 1
[0051] Water was sprayed in the moisture conditioning zone 26 with
a high voltage-type moisture conditioning apparatus 34 of FIG. 2.
The voltage applied to the high voltage electrode 42 was 6000
V.
Example 2
[0052] Water was charged negatively and sprayed in the moisture
conditioning zone 26, while the PVA coating film before entering
the moisture conditioning zone 26 was charged positively, with a
charging-type-moisture conditioning apparatus 60 of FIG. 4.
Example 3
[0053] Water was sprayed in the moisture conditioning zone 26 with
a magnetization-type moisture conditioning apparatus 50 of FIG. 3.
As the magnetized water generating equipment 52, a ferrite magnet
was used. A magnetic force of 3000 Gauss was applied to the
water.
[0054] In all of the above described comparative example and
examples 1 to 3, the temperature in the moisture conditioning zone
26 was kept at 26.degree. C. and the humidity at 55% RH.
[0055] The results are shown in FIG. 5. In FIG. 5, .diamond.,
.quadrature., .DELTA. and .largecircle. each represent the results
of comparative example, example 1, which employed a high
voltage-type moisture conditioning apparatus, example 2, which
employed a charging-type-moisture conditioning apparatus, and
example 3, which employed a magnetization-type-moisture
conditioning apparatus. In FIG. 5, the residence time (second) of
the conveyed substrate 14 in the moisture conditioning zone 26 is
plotted in abscissa and the moisture content (%) of the PVA coating
film having been applied onto the substrate 14 in ordinate.
[0056] As is evident from FIG. 5, the residence time of the
substrate 14 in the moisture conditioning zone 26 until the
moisture content of the PVA coating film reached 4% was about 200
seconds for the comparative example, about 150 seconds for example
1, about 120 seconds for example 2 and about 180 seconds for
example 3. And the residence time of the substrate 14 in the
moisture conditioning zone 26 until the moisture content of the
overcoat layer reached 8% was about 260 seconds for example 1,
about 220 seconds for example 2 and about 400 seconds for example
3. In contrast, for the comparative example, even if the residence
time was increased to 500 seconds or longer, the moisture content
of the overcoat layer was increased to 6% or more at the most.
[0057] As can be seen from the results, in examples 1 to 3,
moisturizing of the PVA coating film could be performed in a
shorter time than in the comparative example. In examples 1 and 2,
the moisture content of the PVA coating film increased in
proportion to an increase in the residence time of the substrate in
the moisture conditioning zone. Particularly in example 2, the
moisture content increased almost linearly in proportion to an
increase in the residence time. The reason better results were
obtained in example 2 than in examples 1 and 3 is probably that in
example 2, which employed a charging-type moisture conditioning
apparatus, when applying a high voltage to water, the water was not
only charged negatively, but made into fine water particles,
whereby both charging effect and
making-water-into-minute-water-particles effect were produced.
[0058] As described so far, the present invention enables the
moisturizing of the PVA coating film in a short time and at high
efficiency, thereby realizing a productivity increase; at the same
time, it does not require an increase in the path length of the
moisture conditioning zone, thereby contributing to cost saving as
well as space saving.
[0059] In the above examples, the present invention has been
described in terms of the case where the object to be moisture
conditioned is a PVA coating film; however, the same results can
also be obtained when applying the present invention to the
moistening line of corrugated board production or resin film
production.
* * * * *