JP2003228176A - Device for controlling water content in coating film layer and method for manufacturing lithographic printing plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device for controlling the water content in a coating film layer so as to control the water content included in a coating film layer formed on a supporting body to the objective water content with high accuracy. <P>SOLUTION: Specified objective temperature OT and objective humidity OH are each determined for an air condition controlling part 48 by a controller 40 according to the objective water content determined on the basis of the kind of a lithographic printing plate. The temperature and humidity of the air sucked from the outside are controlled to the objective temperature OT and objective humidity OH, respectively, by an air conditioning part 44 and the air is supplied into a duct 46. The air with controlled temperature and humidity is blown as air conditioning flow into a humidity controlling chamber 36. The overcoat layer on an aluminum web carried into the humidity controlling chamber 36 absorbs the water included in the air conditioning flow to change its water content with time. The air conditioning part 44 is subjected to the feedback control by the controller 40 based on the water content SW measured by a water content sensor 54. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a water content adjusting device for a film layer, which adjusts the water content contained in the film layer formed by applying a coating liquid containing an organic solvent, water and the like on a support, The present invention relates to a method for producing a lithographic printing plate using this water content adjusting device.

[0002]

2. Description of the Related Art In recent years, with the development of digital processing technology for image processing, as a photosensitive material for a lithographic printing plate for realizing a direct plate making system, by utilizing photoradical polymerization, it is possible to prevent laser light in the visible region. A photopolymer having high sensitivity may be used. In a lithographic printing plate having a photosensitive layer formed by this photopolymer (hereinafter referred to as "photopolymer type lithographic printing plate"), an image forming surface of the lithographic printing plate is irradiated with a laser beam having a sufficiently narrow beam diameter based on image data. The (photosensitive layer) is scanned to cause a photopolymerization reaction in the photosensitive layer provided on the support to cure the exposed portion. That is, by using the photopolymer type lithographic printing plate, characters, images, etc. can be directly formed on the image forming surface of the lithographic printing plate without using a film original (lith film). Here, in the photopolymer type lithographic printing plate, since oxygen in the air becomes a factor inhibiting the photopolymerization reaction, polyvinyl alcohol (PV
An overcoat layer is provided as an oxygen barrier film by a transparent resin such as A), and the photosensitive layer is covered with this overcoat layer.

In many cases, the support of the lithographic printing plate as described above is one side of a long strip aluminum plate made of aluminum or an alloy mainly containing aluminum (hereinafter referred to as "aluminum alloy"), or After both surfaces are roughened, anodized film is formed by anodic oxidation to improve abrasion resistance. This support has a photosensitive material (photopolymer) on its anodized film.
Is applied and dried to form a photosensitive layer, and then PVA is applied so as to cover the entire surface of the photosensitive layer and dried to form an overcoat layer. The web as a processing material for the lithographic printing plate produced in this way is once wound into a roll, and then supplied as a web roll to the lithographic printing plate processing line to attach the protective interleaving paper. The product is cut into the product size, and the product is made into a lithographic printing plate.

[0004]

In the lithographic printing plate as described above, it is known that the water content of the overcoat layer greatly affects the product quality, and if the water content is large, the sensitivity is increased. Then, there is a problem that fog failure is likely to occur, and sensitivity is lowered when the water content is small. Therefore, in the planographic printing plate, if the water content of the overcoat layer is not within the proper range, the quality becomes unstable.

In recent years, various types of photopolymer type lithographic printing plates having different characteristics have been developed according to various needs of users, and these photopolymer type lithographic printing plates have various characteristics such as photosensitivity. Accordingly, the appropriate water content in the overcoat layer varies. Therefore, in the lithographic printing plate production line, it is required to accurately adjust the water content of the overcoat layer to a different target value depending on the type of the photopolymer type lithographic printing plate.

In view of the above facts, an object of the present invention is to provide a water content adjusting device for a coating layer capable of accurately adjusting the water content contained in the coating layer formed on a support to a target water content. To provide.

In view of the above facts, another object of the present invention is to preset the water content contained in the overcoat layer formed on the surface of the photosensitive layer or the heat sensitive layer according to the type of the lithographic printing plate. Another object of the present invention is to provide a method for producing a lithographic printing plate capable of achieving a target water content.

[0008]

According to the coating layer water content adjusting device of the present invention, the humidity control means controls the water content of the coating layer in the humidity control zone to the target water content. When the water content of the coating layer formed on the support is different from the target water content by controlling the humidity control means based on the measured water content and the target water content measured by the water content measurement means, , The moisture content of the coating layer that has entered the humidity control zone can be made close to the target moisture content over time, and if the coating layer is maintained in the humidity control zone for a sufficient time, The water content can be set to the target water content, and if the water content of the coating layer formed on the support before entering the humidity control zone matches the target water content, the water content can enter the humidity control zone. The water content of the coating layer can be stably maintained at the target water content. The water content of the coating layer on the lifting member can be adjusted to the target moisture content.

That is, the water content of the coating film layer of the support that has entered the humidity control zone depends on the water content contained in the coating film immediately before entering the humidity control zone and the level of humidity in the air. The amount of water that penetrates into the coating layer from the inside and the amount of moisture that evaporates from the coating layer into the air approach an amount that equilibrates over time,
After a sufficient time has passed in the humidity control zone, the amount of water entering the coating layer and the amount of water evaporating converge to an amount such that they are in equilibrium.

Therefore, before entering the humidity control zone, the water content of the coating layer (water content before adjustment) is compared with the target water content, and if the water content before adjustment is lower than the target water content, If the humidity in the humidity zone is higher than the equilibrium with the pre-adjustment water content, and the pre-adjustment water content is higher than the target water content, the humidity in the humidity control zone is balanced with the pre-adjustment water content. The moisture content of the coating layer in the humidity control zone can be made closer to the target moisture content with time by lowering the humidity.

At this time, it is necessary to measure the water content of the coating film layer by the water content measuring means at least immediately after the coating film layer is removed from the humidity control zone. According to the measured water content, the humidity in the humidity control zone is controlled. The variable control (feedback control) makes it possible to adjust the water content of the coating layer to the target water content within a limited time (passing time). If the water content of the coating layer just before entering the humidity control zone cannot be estimated with sufficient accuracy, measure the water content of the coating layer before and after passing through the humidity control zone, It is preferable that the humidity in the humidity control zone is variably controlled (feedforward control and feedback control) according to the respective measured water contents.

According to the method for producing a lithographic printing plate of the present invention, after a photosensitive layer or a heat sensitive layer is formed on a support,
The water content contained in the overcoat layer formed on the surface of the photosensitive layer or the heat-sensitive layer is adjusted by the water content adjusting device for the coating layer according to the present invention to a target content preset according to the type of the planographic printing plate. By adjusting the water content, it is possible to accurately adjust the water content contained in the overcoat layer formed on the surface of the photosensitive layer or the heat-sensitive layer to a target water content preset according to the type of the lithographic printing plate. Therefore, it is possible to effectively prevent the quality of the planographic printing plate from becoming unstable due to the influence of the water content of the overcoat layer.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION A lithographic printing plate manufacturing line to which a water content adjusting device for an overcoat layer according to an embodiment of the present invention is applied will be described below with reference to the drawings.

(First Embodiment) FIG. 1 shows a lithographic printing plate manufacturing line according to a first embodiment of the present invention.
A delivery device 16 is arranged on the most upstream side of the manufacturing line 10 (on the left side of FIG. 1).
For example, an aluminum coil 14 in which an aluminum web 12 having a thickness of 0.1 to 0.5 mm is wound into a roll is loaded. The delivery device 16 delivers the aluminum web 12 to the downstream side at a speed corresponding to the production speed of the entire production line 10. Here, the aluminum web 12 as a material of the lithographic printing plate support is, for example, JIS 1050 material, JIS 11
00 material, JIS1070 material, Al-Mg alloy, Al-
A Mn-based alloy, an Al-Mn-Mg-based alloy, an Al-Zr-based alloy, an Al-Mg-Si-based alloy, or the like can be applied.

In the production line 10, a mechanical or electrochemical roughening device 22 is arranged on the downstream side of the delivery device 16, and the roughening device 22 roughens the surface of the aluminum web 12. Process. The production line 10 is provided with an anodizing device 24 that anodizes the aluminum web 12 that has been roughened. The anodizing device 24 anodizes the surface of the aluminum web 12 by a known submerged power supply method to form an anodized film having high hardness on the surface of the aluminum web 12. At this time, the surface of the aluminum web 12, the anodized film of 0.1 to 10 g / m ^2, more preferably anodized film 0.3 to 5 g / m ² is formed.

As shown in FIG. 1, a coating device 26 and a drying device 28 for the photosensitive coating liquid on the aluminum web 12 are installed downstream of the anodizing device 24.
The coating device 26 coats the surface of the aluminum web 12 with a photosensitive coating liquid by, for example, bar coating (or rod coating) to form a photosensitive layer having a constant thickness. When manufacturing a thermal type lithographic printing plate, the coating device 2
6 is a heat-sensitive coating liquid instead of the photosensitive coating liquid, which is an aluminum web 12
Will be applied to. As the drying device 28 arranged on the downstream side of the coating device 26, for example, a hot air type for blowing hot air into a drying tank having a heat insulating structure and drying the photosensitive layer on the aluminum web 12 transported in the drying tank is used. What is used.

Downstream of the drying device 28, a coating device 30 and a drying device 32 for an overcoat coating liquid such as polyvinyl alcohol (PVA) are installed. The coating device 30 coats the overcoat coating liquid on the surface of the photosensitive layer on the aluminum web 12 by, for example, slide coating to form an overcoat layer having a constant thickness. Here, the slide coating means that the aluminum web 12 has a medium viscosity (approximately 50 m).
(Pa or less) is a kind of film forming method for forming a coating film layer (overcoat layer) with an overcoat coating liquid, and specifically, the overcoat coating liquid is supplied onto an inclined surface. Is formed into a film having a constant thickness while flowing along the inclined surface, and the overcoat coating liquid formed into the film is flow-transferred onto the photosensitive layer of the aluminum web 12 so that the overcoat is formed on the photosensitive layer. A coat layer is formed.

The drying device 32 arranged on the downstream side of the coating device 30 has basically the same structure as the drying device 28, and the overcoat layer formed on the aluminum web 12 moving in the drying tank. Dry with hot air. This allows
An overcoat layer as an oxygen barrier layer is formed on the aluminum web 12 so as to cover the photosensitive layer. However, since the appropriate drying conditions are different between the photosensitive layer and the overcoat layer, the temperature of the hot air supplied to the drying tank and the length along the transport direction of the drying tank are appropriately set according to the respective drying conditions. It As a result, the overcoat layer on the aluminum web 12 is in an absolutely dry state in which the water content is sufficiently reduced when the drying device 32 is removed.

In the production line 10, a water content adjusting device 34 is installed on the downstream side of the drying device 32. The water content adjusting device 34 determines the water content of the overcoat layer formed on the aluminum web 12 as a weight ratio (hereinafter, referred to as “water content”) depending on the type of the planographic printing plate. It is adjusted accordingly.

As shown in FIG. 2, the water content adjusting device 34.
A casing-shaped humidity control tank 36 is provided along the conveyance path of the aluminum web 12. The internal space of the humidity control tank 36 constitutes a humidity control zone for adjusting the water content of the overcoat layer. Inside the humidity control tank 36, the aluminum web 1
A plurality of (five in FIG. 2) pass rolls 38 for transporting and guiding 2 are arranged. These pass rolls 38 are provided along the conveyance path of the aluminum web 12 to the humidity control tank 3
6 are alternately arranged on the top side and the bottom side, and the humidity control tank 36
Inside, the aluminum web 12 is conveyed up and down along a spider-like path. As a result, the path length (path length) of the aluminum web 12 is extended compared to the case where the aluminum web 12 is conveyed linearly, and the aluminum web 12 is moved to the humidity control tank 36.
You can delay the transit time from entering the vehicle to exiting. In the humidity control tank 36, a web handling device for tension adjustment including a drive roll, a dancer mechanism, etc. may be provided instead of or in addition to the pass roll 38.

As shown in FIG. 2, the water content adjusting device 34.
In addition to inputting and outputting various information to and from a higher-level process computer (not shown) that performs production management,
A controller 40 for controlling the entire apparatus is provided, and an air conditioning unit 42 for adjusting the humidity and temperature inside the humidity control tank 36 is provided. The air conditioning unit 42 is provided with an air conditioning unit 44 and an air conditioning control unit 48 that are connected to the humidity control tank 36 via a duct 46. The air conditioning unit 44 is configured by combining a heat exchanger, a dehumidifier, a humidifier, etc., and can adjust the temperature and humidity of the air sucked from the outside. Further, the air conditioning control unit 48 controls the air conditioning unit 44 according to the target temperature OT and the target humidity OH set by the controller 40. Controller 4
0 inputs / outputs various information to / from a higher-level process computer (not shown) that controls production of the entire manufacturing line 10 and controls the water content adjusting device 34 according to the type of the planographic printing plate.

A blower 50 and an air filter 52 are arranged in the air conditioning duct 46 of the air conditioning unit 42. The blower 50 sends the air whose humidity and temperature have been adjusted by the air conditioner 44 to the humidity control tank 36 side. The air filter 52 removes foreign matters such as dust from the air, and the air blower 50 supplies the air as conditioned air having a constant flow velocity into the humidity control tank 36. At this time, the air conditioning control unit 48 sets the temperature and humidity of the conditioned air supplied to the humidity control tank 36 by the air conditioning unit 44 to the target temperature OT and the target humidity OH.
The air conditioner 44 is controlled. Further, the humidity control tank 36 has a rectifying plate,
A rectifying member (not shown) such as a nozzle is arranged, and the conditioned air blown from the duct 46 into the humidity control tank 36 is rectified by the rectifying member to form an overcoat on the product web 58. After being sprayed on the layer or flowing along the surface of the overcoat layer, it is discharged to the outside of the tank through an exhaust port (not shown) provided in the humidity control tank 36.

As shown in FIG. 2, a water content sensor 54 is arranged in the production line 10 immediately after the humidity control tank 36 so as to face the overcoat layer of the aluminum web 12. The water content sensor 54 continuously measures the water content in the overcoat layer by a known infrared reflection method, and outputs a measurement signal SW corresponding to the measured value to the controller 40.
Output to. The controller 40 calculates the deviation between the target value (target water content OW) of the water content and the measured value (measured water content SW) at regular intervals based on the measurement signal from the water content sensor 54, and based on this deviation. Then, the target temperature OT and the target humidity OH are calculated, and the target temperature OT and the target humidity OH set in the air conditioning unit 44 are updated.

In the production line 10 of this embodiment, the aluminum web 12 passes through the water content adjusting device 34,
The production of the product web 58 as a processing material for the planographic printing plate is completed. The product web 58 is wound into a roll by a web winding device 56 to form a product roll 60.
The product roll 60 is supplied to a lithographic printing plate processing line (not shown), and a protective interleaving paper is stuck, slitted, cut or the like on the lithographic printing plate processing line to be processed into a lithographic printing plate of a predetermined size. . The planographic printing plates are stacked in a predetermined number by an accumulating device provided at the end of the processing line to form a bundle, which is packaged (interior) with interior paper having a light-shielding property and a moisture-proof property. It is packaged (exterior) with exterior paper such as corrugated board and stored until the time of shipment. In addition, the product web 58 is directly sent to the processing line without being wound as the product roll 60,
You may make it process into a lithographic printing plate.

The lithographic printing plate processing line is provided with a plurality of processing zones partitioned from the outside along the conveyance path of the product web 58, and these processing zones respectively prevent the inflow of air from the outside. At the same time, the temperature and humidity of the internal air are adjusted so that the change in water content of the overcoat layer during processing is suppressed. Further, the product roll 60 is stored in a state of being wrapped with a moisture-proof packaging material as needed, and even in the interior of a warehouse or the like where the product roll 60 is stored, a change with time of the water content of the overcoat layer is suppressed. As described above, the temperature and humidity are adjusted by the air conditioner.

Next, the operation of the water content adjusting device 34 according to the present embodiment configured as described above will be described. In a lithographic printing plate having an overcoat layer, the sensitivity to exposure laser light of the photosensitive layer or the heat-sensitive layer changes depending on the water content of the overcoat layer, depending on the type, namely, the type of the photosensitive layer or the heat-sensitive layer, The appropriate value of the water content of the overcoat layer changes depending on the composition and thickness of the overcoat layer. Therefore, in the production line 10, after the overcoat layer of the product web 58 is once dried by the drying device 32, the water content of the overcoat layer is adjusted by the water content adjusting device 34 according to the type of the planographic printing plate. The target water content OW set by the above is adjusted.

The controller 40 determines the type of lithographic printing plate to be manufactured based on information from a process computer (not shown) for managing the entire manufacturing line 10, and creates a data table in advance according to the type of the lithographic printing plate. The target water content OW, the initial value of the target temperature OT, and the initial value of the target temperature OH that have been set are read out, and the target temperature O
The initial value of T and the initial value of the target temperature OH are set to the air conditioning control unit 48.
Set to. As a result, the air conditioning unit 44 adjusts the temperature and humidity of the air sucked from the outside to the initial value of the target temperature OT and the initial value of the target temperature OH, respectively, and supplies them into the duct 46, and the temperature and humidity are adjusted. The air is blown into the humidity control tank 36 as conditioned air.

On the other hand, the overcoat layer on the aluminum web carried into the humidity control tank 36 is mainly composed of the humidity in the humidity control tank 36 and the time from when it enters the humidity control tank 36 to when it is removed (passing time). ) The water content is adjusted according to T. Specifically, the overcoat layer that has been completely dried is the humidity control tank 36.
When the conditioned air having a sufficiently low humidity is supplied to the inside, even if the conditioned air passes through the humidity control tank 36, the water content hardly changes and the water content remains low. When the humidity is high to some extent, the water content (humidity) contained in the conditioned air is absorbed and the water content increases with time. That is, when the humidity of the conditioned air is higher than the humidity (equilibrium humidity) that is in equilibrium with the water content of the overcoat layer, the overcoat layer that has entered the humidity control tank 36 gradually increases due to the moisture absorption reaction from the air. When the water content increases and the water content of the overcoat layer reaches a value in equilibrium with the humidity of the air, it does not change.

At this time, the moisture absorption rate of the overcoat layer becomes faster as the actual air humidity in the humidity control tank 36 becomes higher than the equilibrium humidity, and the saturated water vapor amount also changes according to the air temperature in the humidity control tank 36. Because it changes, it is affected by extreme changes in air temperature. Further, when the size of the aluminum web 12 changes or the thickness of the overcoat layer changes, the absolute moisture absorption amount (water content) until the overdried layer in the absolutely dry state reaches the target water content OW. Since it changes, the time until the overcoat layer reaches the target water content OW also changes. On the other hand, the transit time T of the aluminum web 12 is proportional to the transport speed of the aluminum web 12, and this transport speed is substantially constant for each type of lithographic printing plate, but the size of the aluminum web 12, the production speed, etc. It may be adjusted within a predetermined range according to. Therefore, the passage time T is not always constant even when the type of lithographic printing plate is the same.

Therefore, the overcoat layer on the aluminum web 12 is adjusted to have a water content substantially corresponding to the air humidity (target humidity OH) in the humidity control tank 36 by passing through the humidity control tank 36. The passage time T, the size of the aluminum web 12 and the variation in the thickness of the overcoat layer are factors that cause the variation in the water content. In order to prevent the water content of the overcoat layer from deviating from the target water content OW due to these fluctuation factors, the controller 40 feedback-controls the air conditioning unit 42 based on the measured water content SW from the water content sensor 54. Specifically, the controller 40 compares the measured water content SW with the center value of the target water content OW at every predetermined cycle, calculates the deviation E, and the magnitude and direction of the deviation E (on the negative side). The new target temperature OT and the target humidity OH are calculated according to the deviation or the plus side deviation), and the target temperature OT and the target humidity OH are set in the air conditioning control unit 48. As a result, the temperature and humidity of the air are newly adjusted by the air conditioning unit 44 to the target temperature OT and the target humidity OH set in the air conditioning control unit 48, and this air is supplied as air conditioning air into the humidity control tank 36.

Here, when the controller 40 feedback-controls the air conditioning unit 42 based on the measured water content SW, various known feedback controls can be used. For example, PID control and fuzzy control are used. A new target temperature OT and target humidity OH are calculated. However, if the target temperature OT is greatly changed, it becomes a factor of variation in the moisture absorption rate of the overcoat layer. From this, the water content adjusting device 34 of the present embodiment
Then, the air conditioning unit 44 is controlled so that the target temperature OT is kept substantially constant even if the target humidity OH changes.

Further, the controller outputs an alarm signal when the measured water content SW is out of the range from the lower limit value to the upper limit value of the target water content OW. This alarm signal is continuously output by the controller 40 until the measured water content SW returns to the range from the lower limit value to the upper limit value of the target water content OW. The alarm signal is used, for example, to notify a quality abnormality to an operator by an alarm sound generated from a buzzer or the like, an alarm display on a display or the like, and by being output to the process computer, the process computer, for example, A portion where the water content of the overcoat layer deviates from the target water content OW is tracked, and marking is performed on this portion with a marker device or the like. As a result, the operator can detect the cause of the abnormality at an early stage, and can stop the production line 10 and stop the production of the product web 58 having the abnormal quality, if necessary.
Further, by marking the abnormal portion of the product web 58, the abnormal portion can be cut off and re-inspected easily in the subsequent process.

According to the water content adjusting device 34 according to this embodiment described above, the controller 40 causes the water content of the overcoat layer on the aluminum web 12 in the humidity control tank 36 to reach the target water content OW. The water content of the overcoat layer formed on the aluminum web 12 passing through the humidity control tank 36 is controlled by feedback-controlling the air conditioning unit 42 based on the measured water content SW measured by the rate sensor 54 and the target water content OW. Since the rate can be stably adjusted to a target water content according to the type of the lithographic printing plate, the lithographic printing plate is affected by the water content of the overcoat layer formed on the surface of the photosensitive layer or the heat-sensitive layer. It is possible to effectively prevent the quality of the printing plate from becoming unstable.

(Second Embodiment) FIG. 3 shows a water content adjusting device 62 according to a second embodiment of the present invention. The water content adjusting device 62 is the water content adjusting device 3 according to the first embodiment.
4 is applied to the production line 10. In the members of the water content adjusting device 62 according to the second embodiment, members having the same configuration and operation as those of the water content adjusting device 34 according to the first embodiment are designated by the same reference numerals and description thereof will be omitted.

The water content adjusting device 62 shown in FIG. 3 differs from the water content adjusting device 34 shown in FIG. 2 in that a path length adjusting mechanism 64 for adjusting the path length of the aluminum web 12 in the humidity control tank 36 is provided. They are arranged and the function of controlling the path length adjusting mechanism 64 is added to the controller 78. Here, the path length L adjusted by the path length adjusting mechanism 64 is the length at which the aluminum web 12 stretched by the path roll 38 is present in the humidity control tank 36. The passage time T, which is the time taken for the aluminum web 12 to pass through the humidity control tank 36, is determined by the transport speed of the web 12.

The path length adjusting mechanism 64 is provided with a carriage 66 that pivotally supports the two upper path rolls 38 of the upper and lower path rolls 38 alternately arranged in the humidity control tank 36. ing. The carriage 66 is supported together with the two pass rolls 38 arranged on the upper side in the humidity control tank 36 so as to be vertically movable. Therefore, depending on the position of the carriage 66 along the vertical direction,
The path length L of the aluminum web 12 in the humidity control tank 36 changes. The path length adjusting mechanism 64 includes a loop-shaped belt member 6 stretched by a pair of sprockets 68 and 70.
Equipped with 7. Here, one sprocket 68 is supported above the upper limit position in the movable range of the carriage 66, and the other sprocket 70 is held by the carriage 66.
Is supported below the lower limit position in the movable range. Further, the carriage 66 is connected to the belt member 67 via a connecting arm 71.

The path length adjusting mechanism 64 is provided with a path length control unit 72 as a control unit for the entire mechanism, and a drive motor 74 and an encoder 76 connected to the sprocket 68 and the sprocket 70, respectively.
Here, the drive motor 74 is configured by a servo controllable motor, receives a drive signal from the path length control unit 72, and rotates by a necessary amount in a direction corresponding to the drive signal. The encoder 76 also outputs to the path length controller 72 a number of measurement pulses that are proportional to the amount of rotation of the sprocket 70.

On the other hand, when changing the path length L, the controller 78 calculates the control direction and control distance of the carriage 66 from the difference between the current path length L and the changed path length L, and this control direction is calculated. And a position control signal CP corresponding to the control distance to the path length controller 72. Upon receiving the position control signal CP, the path length control unit 72 measures the moving distance of the carriage 66 by the number of measurement pulses input from the encoder 76 while rotating the drive motor 74 in the rotation direction corresponding to the control direction. The drive motor 74 is stopped at the timing when the measured distance matches the control distance. As a result, the path length L of the aluminum web 12 in the humidity control tank 36
Is adjusted to the required length.

The path length adjusting mechanism 6 according to the present embodiment.
In FIG. 4, the belt member 67 driven by the drive motor 74 is used to move the carriage 66. However, any mechanism may be used as long as the mechanism can drive the carriage 66 up and down. A linear actuator that operates by hydraulic pressure, gas pressure, a stepping motor, or the like may be connected to the carriage 66, and the carriage 66 may be moved up and down by this linear actuator. Instead of moving the pass roll 38 up and down, the humidity control tank 36 may be configured to be expandable and contractable to adjust the pass length L. Here, the controller 78 is basically the same as the controller 40 according to the first embodiment.
By performing feedback control of the air conditioning unit 42 based on the measured water content SW from the water content sensor 54, when the aluminum web 12 passes through the humidity control tank 36, the water content of the overcoat layer becomes the target water content OW. adjust. Further, the controller 78 adjusts the path length adjusting mechanism 64 so that the moisture content of the overcoat layer in the humidity control tank 36 matches the target.
The control for adjusting the path length L is performed according to. Specifically, for example, the controller 78 adjusts the path length L by the path length adjusting mechanism 64 so that the passage time T is always kept constant even when the transport speed of the aluminum web 12 changes. As a result, there is no change in the passage time T, which is a variation factor with respect to the water content, so that the water content of the overcoat layer can be adjusted to the target water content OW with higher accuracy than in the case of the first embodiment. Further, in addition to the control according to the change of the transport speed, the path length L is adjusted according to the change of the size of the aluminum web 12 which is another variation factor to the water content, and the water content before the adjustment of the overcoat layer is adjusted. The path length L may be adjusted according to the difference (control amount) from the target water content OW so that the passage time T becomes longer as the control amount increases.

In the first and second embodiments, only the case of increasing the water content of the overcoat layer formed on the aluminum web 12 has been described, but the humidity control tanks 36 and 62 are used to control the humidity control tank 36. It goes without saying that it is possible to maintain the water content of the overcoat layer in the absolutely dry state and to reduce the water content of the overcoat layer which is not in the completely dry state. Further, in the first embodiment and the second embodiment, the water content of the overcoat layer formed on the aluminum web 12 carried into the humidity control tank 36 is dried by the drying device 32 and is substantially constant. When the water content of the overcoat layer before being carried into the humidity control tank 36 cannot be estimated with sufficient accuracy, in order to reliably adjust the water content of the overcoat layer to the target water content OW, the humidity control tank The water content of the overcoat layer before being carried into the container 36 is measured by a water content sensor, and the air conditioning unit 44 (in the second embodiment, the air conditioning unit 44 or the path length adjusting mechanism is used based on the measured value (measured water content). 64) needs to be feed forward controlled.

According to the water content adjusting device of the present invention, it is possible to adjust the water content of any coating layer provided that the coating layer formed on the support has hygroscopicity. It is also possible to adjust the water content of the support or the water content of both the support and the coating layer, if the support itself has a hygroscopic property such as paper and hydrophilic resin.
It is also possible to adjust the water content of the protective interleaving paper stuck to the product web 58 or the like.

[0042]

As described above, according to the water content adjusting device of the present invention, the water content contained in the coating layer formed on the support can be adjusted to the target water content with high accuracy.

Further, according to the method of manufacturing a lithographic printing plate of the present invention, the water content contained in the overcoat layer formed on the surface of the photosensitive layer or the heat-sensitive layer is preset according to the type of the lithographic printing plate. The target water content can be adjusted.

[Brief description of drawings]

FIG. 1 is a side view schematically showing a configuration of a lithographic printing plate manufacturing line to which a water content adjusting device according to an embodiment of the present invention is applied.

FIG. 2 is a block diagram showing a configuration of a water content adjusting device according to the first embodiment of the present invention.

FIG. 3 is a block diagram showing a configuration of a water content adjusting device according to a second embodiment of the present invention.

[Explanation of symbols]

12 Aluminum web (support) 34 Water content adjusting device 36 Humidity control tank (humidity control zone) 40 controller (humidity control means) 42 Air conditioning unit (humidity control means) 44 Air conditioner (humidity control means) 48 Air conditioning control unit (humidity control means) 54 Water content sensor (water content measuring means) 58 product web (lithographic printing plate) 62 Water content adjusting device (humidity adjusting means) 64 path length adjusting mechanism (path length adjusting means) 78 Controller (humidity control means)

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2H025 AA01 AB03 AC08 EA10 FA10                 2H084 AA30 AE05 BB02 BB13 CC05                 2H096 AA06 JA10 LA30                 4F042 AA22 BA03 BA19 BA20 BA26                       DB02 DB26 DB36 DC03 DH02                       DH09

Claims (4)

[Claims] 1. A water content adjusting device for a coating layer for adjusting the water content contained in a coating layer formed by applying a coating liquid on a support to a target water content, which is formed on a support. A water content measuring means for measuring the water content of the coating layer, a humidity controlling means for adjusting the humidity in the humidity controlling zone through which the support having the coating layer is formed, and a coating film in the humidity controlling zone. A humidity control means for controlling the humidity control means on the basis of the measured water content measured by the water content measurement means and the target water content so that the water content of the layer becomes the target water content. A water content adjusting device for a coating film layer. 2. A path length adjusting means for increasing or decreasing the path length so that the path length of the support in the humidity adjusting zone matches the target path length set by the humidity controlling means. The water content adjusting device for a coating layer according to claim 1. 3. An alarm means for outputting an alarm signal when the measured water content measured by the water content measuring means after the passage through the humidity control zone is out of the target water content range. The water content adjusting device for a coating layer according to claim 1 or 2. 4. A method of producing a lithographic printing plate, comprising forming a photosensitive layer or a heat-sensitive layer on a support, and then forming an overcoat layer on the surface of the photosensitive layer or the heat-sensitive layer by applying a coating liquid. The coating layer according to claim 1, 2 or 3, wherein the water content contained in the overcoat layer formed on the surface of the photosensitive layer or the heat-sensitive layer after forming the photosensitive layer or the heat-sensitive layer on the support. A method for producing a lithographic printing plate, comprising the step of adjusting the water content by the water content adjusting device according to the type of the lithographic printing plate to a preset target water content.