Waterless offset master plate manufacturing method and manufacturing device

Abstract

To provide a manufacturing method and apparatus in which a peelable film has the high coatability with respect to a substrate while using a material of an easy-to-peel film for the peelable film for substrate reproduction in a step of manufacturing a waterless offset original plate of a columnar substrate, which can perform stable printing and can manufacture a high-quality original plate.SOLUTION: A manufacturing method includes: a first application step of discharging droplets of a peelable film material from a first applicator to a peripheral surface of a columnar substrate while rotating a shaft of the columnar substrate as the central shaft by using a peelable material with a specific physical property, and forming a coating film by laminating the peelable film materials by making the first applicator reciprocate in the axial direction of the columnar substrate while spraying the droplets of the peelable film material to the surface of the columnar substrate; a step of forming a peelable film on the columnar substrate by performing solidification of the peelable film material applied onto the columnar substrate; and a second application step of discharging a silicone film material from a second applicator and applying the silicone film material to the surface of the peelable film.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method and an apparatus for producing a waterless offset master plate. [Background technology]

[0002] Waterless offset printing is a lithographic printing technique characterized by the use of an ink-repellent silicone material instead of the dampening water used in regular offset printing to repel oil-based ink. In waterless offset printing, the master plate is generally made of a plate such as aluminum with a silicone film formed on its surface (Patent Document 1).

[0003] Specifically, a silicone material is continuously applied to a long continuous plate, which is then cut to individual lengths depending on the required size of the master plate. A printing pattern is then processed onto the master plate to make a printing plate, which is then wrapped around a cylindrical substrate called a plate cylinder and used in a printing press.

[0004] However, in this case, there is a problem that the edge of the printing plate forms a seam in the circumferential direction on the cylindrical substrate, making it impossible to print near this seam. To address this problem, Patent Document 2 proposes an offset master plate that is a seamless cylindrical shape rather than the conventional plate shape. Furthermore, Patent Document 2 discloses a method for recycling printing plates by removing the resist pattern portion from the surface of the cylindrical substrate by ultrasonic cleaning, chemical cleaning, or the like, after applying a resist pattern coated on the matte surface of the cylindrical substrate.

[0005] Furthermore, Patent Document 3 proposes that in waterless offset printing, a seamless printing sleeve be formed by coating the surface of the printing sleeve with a silicone resin layer. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 05-094008 [Patent Document 2] International Publication No. 2017 / 104327 [Patent Document 3] Domestic Publication No. 2017 / 077825 Summary of the Invention [Problem to be solved by the invention]

[0007] When the substrate shape of the master plate changes from the conventional plate shape to a cylindrical shape, there are some processes in the manufacturing process that make it difficult to use conventional methods. One such process is the process of forming the necessary functional film on the substrate. For example, when using a cylindrical substrate, cylindrical substrates with different outer diameters are used depending on the size of the master plate. However, since they cannot be stacked and compacted like plate-shaped substrates during storage and transportation, the master plate may be manufactured at a printing company or printing manufacturer. When the master plate is manufactured at a printing company or printing manufacturer, only the required number of master plates are produced at that location, and due to storage space and transportation load, it is preferable to repeatedly reuse the same cylindrical substrate. Reusing this cylindrical substrate requires a recycling process in which the functional film formed on the surface of the cylindrical substrate is removed after use as a printing plate and then a new functional film is formed. Silicone materials used as functional films for waterless offset master plates tend to adhere to the cylindrical substrate and are difficult to remove until completely removed. Therefore, a recycling method can be considered in which an easily peelable release film is provided on the cylindrical substrate, a silicone film is formed on the release film, and the release film is peeled off along with the silicone film when recycling the substrate. However, the release film formed on the surface of the cylindrical substrate must not easily peel off during printing and must remain attached to the cylindrical substrate.

[0008] In other words, the release film provided for recycling the cylindrical substrate needs to be easily peelable in the recycling process, and also needs to firmly coat the cylindrical substrate and not peel off in the printing process, which are contradictory functions. However, in the production of waterless offset master plates, applying a liquid release film material to the surface of the cylindrical substrate to form a release film has not been considered to achieve both easy peeling during peeling and strong coating on the cylindrical substrate.

[0009] In other words, the problem to be solved by the present invention is to manufacture a seamless waterless offset master plate with no seams on the surface of a cylindrical substrate, which can be easily peeled off from the cylindrical substrate, making the cylindrical substrate recyclable, while maintaining high coverage on the substrate during printing and allowing stable printing, and the object of the present invention is to provide a manufacturing method and manufacturing apparatus for this purpose. [Means for solving the problem]

[0010] In order to solve the above problems, the present invention provides a method and apparatus for producing a waterless offset master plate having the following configuration. (1) A first application step of applying a liquid release film material to the surface of a cylindrical substrate; and a second application step of drying and solidifying the release film material to form a cylindrical substrate. condition group In a method for producing a waterless offset master plate, the method includes a first solidification step of forming a release film on the surface of a material, a second coating step of coating a silicone film material on the surface of the release film, and a second solidification step of drying and solidifying the silicone film material, the release film material has a tensile strength [N / mm ] of 100 μm or less when the coating film thickness is 100 μm or less in standard release characteristics after drying and solidification. 2 a release film material in which the product of the adhesive strength [N / mm] and the coating thickness [mm] exceeds the adhesive strength [N / mm] of the release film, and the first coating step involves discharging the release film material in droplets from a first applicator onto the circumferential surface of the cylindrical substrate while rotating the cylindrical substrate about its axis, and of surface Drops Shape The aforementioned While spraying the release film material, the first applicator is moved back and forth in the axial direction of the cylindrical substrate. Yoa coating step of laminating the release film material to form a coating film; The first solidification step Following the first coating step, The cylinder Condition The coated release film material is dried and solidified while the substrate is rotated, Condition The release film material applied on the substrate is solidified, and the cylinder is then formed. Condition The method for producing a waterless offset master plate is a process for forming the release film on a substrate, and the second coating process is a process for ejecting the silicone film material from a second applicator and coating the silicone film material on the surface of the release film, and a laminate including at least the release film and a silicone film is formed on the surface of a cylindrical substrate.

[0011] (2) The method for producing a waterless offset master plate according to (1), wherein the second coating step is started in the middle of the first solidification step while the cylindrical substrate is rotated. (3) The first solidification step and the second solidification step are performed to form the cylindrical condition group Wind generated by the rotation of the cylinder or condition group The method for producing a waterless offset master plate according to (1) or (2) is carried out by blowing air from an air nozzle onto the coating surface on the material. (4) A method for producing a waterless offset master plate according to (1) or (2), in which a photocurable resin is used as the release film material, and after the release film material is applied, the substrate is rotated and irradiated with light to solidify the release film material.

[0012] (5) A first coating means having a spray nozzle as a first coating nozzle for applying a first coating material to the peripheral surface of the cylindrical substrate, a second coating means having a second coating nozzle for applying a second coating material to the peripheral surface of the cylindrical substrate, a rotation drive means for rotating the cylindrical substrate around the axis of the cylinder as the central axis, a solidification means for solidifying the coating film applied to the peripheral surface of the cylindrical substrate by blowing air from an air nozzle or irradiating light, a measuring device for measuring the film thickness value of the coating film, and a controller for switching between the first and second coating means and the solidification means, The first and second coating means are equipped with a moving means for repeatedly moving the first spray nozzle and the second spray nozzle back and forth in the direction of the rotation axis of the cylindrical substrate, and further, the coating material is applied by moving the first and second spray nozzles with the moving means while the cylindrical substrate is rotated by the rotation drive means, and the second coating means starts the coating process by the second coating means after stopping the solidification means based on the measurement value of the measuring instrument, in a waterless offset master plate manufacturing apparatus. [Effects of the Invention]

[0013] According to the present invention, when manufacturing a seamless waterless offset master plate without seams on the surface of a cylindrical substrate, a release film material applied to the surface of the cylindrical substrate is solidified to form a release film on the cylindrical substrate, and then a silicone film is formed on the surface of the release layer.This laminate structure makes it easy to release the release layer from the cylindrical substrate, and during printing, it maintains a high level of coverage on the substrate, allowing for stable printing.

[0014] As a result, by using these manufacturing methods and manufacturing devices that are compatible with cylindrical substrates, it is possible to efficiently and with high quality produce waterless offset master plates having an easily peelable film. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a schematic perspective view showing an embodiment of a manufacturing apparatus according to the present invention. [Figure 2] 1 is a schematic front view showing an embodiment of a manufacturing apparatus according to the present invention. [Figure 3] FIG. 2 is a side view showing a first application step and a first solidification step. [Figure 4] FIG. 10 is a side view showing a second application step and a second solidification step. [Figure 5] FIG. 1 is a front view showing a schematic configuration of an apparatus for drying and solidifying a coating film. [Figure 6] FIG. 10 is a schematic perspective view showing a step of forming a laminate. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The present invention will be understood based on the following description and drawings, but the embodiments of the present invention are not limited to these.

[0017] The method for producing a waterless offset master plate of the present invention includes a first coating step of coating the surface of a cylindrical substrate with a liquid release film material, a drying and solidifying step of the release film material, and a second coating step of coating a silicone film material, and a drying and solidifying step of the silicone film material, and a laminate including at least the release film and the silicone film is formed on the surface of the cylindrical substrate. The release film material of the present invention has a standard release characteristic after drying and solidifying, and when the coating film thickness is 100 μm or less, the tensile strength of the release film [N / mm 2 The method uses an easily peelable material in which the product of the adhesive strength [N / mm] and the coating thickness [mm] exceeds the adhesive strength [N / mm] of the release film, and the first coating step is a process of applying the release film material in droplets from a first applicator to the circumferential surface of the cylindrical substrate while rotating the cylindrical substrate around its axis, and spraying the droplets of release film material in the direction of rotation of the cylindrical substrate surface while laminating them to form a coating film.The first solidification step is performed following the first coating step, and the applied release film material is dried and solidified while the cylindrical substrate is rotating, thereby solidifying the release film material applied to the cylindrical substrate and forming the release film on the cylindrical substrate.Then, the second coating step is a process of discharging the silicone film material from a second applicator and applying the silicone film material to the surface of the release film. The release film material refers to a release material that becomes a release film, and the silicone film material refers to a silicone material that forms a silicone film, and a laminate of a release film and a silicone film is sometimes called a functional film.

[0018] In the present invention, the second coating method for coating the silicone material is not limited, but in the following description of the embodiment, the second coating step will be described using a method similar to the first coating step: That is, it is a step in which the release film material is discharged in droplets from a second applicator onto the circumferential surface of the cylindrical substrate while rotating the cylindrical substrate about its axis, and the droplets of silicone material are applied in the direction of rotation of the surface of the cylindrical substrate.

[0019] In the present invention, the silicone material used as the functional film of the waterless offset master plate tends to adhere to the cylindrical substrate and is difficult to peel off. Therefore, by providing an easily peelable release film between the cylindrical substrate and the silicone film, the cylindrical substrate can be easily peeled off. When recycling the cylindrical substrate, the release film is peeled off together with the silicone film. On the other hand, the release film formed on the surface of the cylindrical substrate must have strong coating retention with the cylindrical substrate to prevent peeling of the plate surface during printing.

[0020] The standard release properties required for the release film material of the present invention are as follows. In this invention, the "standard release properties" are an index that represents the release film material based on the properties of a release layer formed thinly on a substrate by coating or the like with the release material. A release film material with good release properties, i.e., easy release properties, allows the release film formed on the substrate to be easily peeled off without breaking when peeled from the substrate, and is related to the tensile strength of the release film itself and the adhesive strength between the substrate and the release film. The standard release properties of the release material used in the waterless offset master plate of the present invention are such that the tensile strength [N] of the release film is greater than the adhesion strength [N] between the substrate and the release film.

[0021] Here, the tensile strength is the material strength of the peelable film material in a film state: T [N / mm 2 ] and can be measured using a tensile testing machine specified in JIS B 7721 (2018). The cross-sectional area [mm 2], it is expressed as T / (W·t). Adhesion strength: P [N / m] can be measured by the adhesive strength measurement method using 90-degree peeling described in JIS Z 0237 (2009), and is expressed as P / W from the width W [mm]. When the thickness of the release film, i.e., the film thickness t, is 100 μm or less, the standard release properties require that the easy-to-peel film material has a T·W·t that exceeds P·W. The standard release properties and the properties of the release film obtained by the manufacturing method of the present invention will be described in detail below.

[0022] First, the configuration of an apparatus for the manufacturing method of the present invention will be described with reference to the drawings.

[0023] <Configuration of manufacturing equipment> Fig. 1 is a schematic diagram showing an example of a waterless offset master manufacturing apparatus 100. Fig. 2 is a front view showing in detail the coating process, which is part of the manufacturing apparatus 100 of Fig. 1, and Figs. 3 and 4 are side views of the coating process, which is also part of the manufacturing apparatus 100 of Fig. 1, with Fig. 3 showing a first coating process and a first solidification process, and Fig. 4 showing a second coating process and a second solidification process. Also, Fig. 5 is a front view showing the drying and solidification process, which is also part of the manufacturing apparatus 100 of Fig. 1.

[0024] 1 shows a first coating process for applying a liquid release film material, which includes at least a first spray nozzle 121a and a first coating head 122a. The release film material is applied in droplets to the surface of a cylindrical substrate. The manufacturing apparatus 100 shown in FIG. 1 rotates a cylindrical substrate 111 (the substrate to be coated) around its axis while moving a first spray nozzle 121a, which dispenses the coating material, back and forth in a direction P, which indicates the axial direction of the cylindrical substrate 111, to coat the outer peripheral surface of the substrate with coating material F in layers. Then, while rotating the cylindrical substrate 111 around its axis, an airflow is sprayed from an airflow solidification means 141 toward the coating material F on the outer peripheral surface of the substrate, thereby drying and solidifying the coating material F.

[0025] In Fig. 1, at least a second spray nozzle 121b and a second coating head 122b are provided as a second coating step for coating a silicone film material, and in Fig. 1 they are on standby away from the cylindrical substrate to carry out the second coating step. Then, although not shown in Fig. 1, after the first coating step and the first solidification step, the second spray nozzle 121b and the second coating head 122b apply the silicone material onto the release film, and after the second solidification step, a silicone film is formed, and a waterless offset printing original plate is produced.

[0026] 1 shows one solidification means 141 using an airflow used in the first solidification step and the second solidification step, but multiple solidification means using an airflow may be provided and each may be used independently for drying and solidifying. Note that, although the solidification means 141 using an airflow is shown in FIG. 1 as a slit-type nozzle having a slit-shaped airflow outlet in the axial direction of the cylindrical substrate, other nozzle shapes may also be used.

[0027] When the airflow is sprayed onto the coating surface on the periphery of the substrate by the airflow solidification means 141, it is preferable to spray the airflow while the cylindrical substrate is rotating so that the airflow is sprayed onto the entire coating surface. This not only promotes drying of the coating by the airflow generated on the substrate surface by the rotation of the substrate, but also suppresses the liquid flow of the coating due to the influence of gravity.

[0028] In this solidification process, the film thickness value of the coating film is measured by the film thickness sensor 151 shown in Figures 3 and 4, and the measured value is input into the sensor controller 152 to detect the layered state of the coating film and control the timing of the end of the first coating process and the start of the first solidification process.In addition, the drying and solidifying state of the coating film may be monitored by measuring changes in the coating film after the end of the first coating process.

[0029] For example, the measurement values input by the sensor controller 152 are transmitted to the interlocking operation controller 150. When the state of the coating film in the first coating step is such that it can be moved to the next step, the first solidification step, the interlocking operation controller 150 issues a command to move to the first solidification step. Then, when the dried and solidified state of the coating film is such that it can be moved to the next step, the second coating step, the interlocking operation controller 150 issues a command to move to the second coating step. In the second coating step, the second spray nozzle 121b shown in FIG. 1 is moved in the axial direction of the cylindrical substrate 111 to apply a silicone functional layer to the surface of the release film. Subsequently, an airflow is sprayed from the airflow solidification means 141 shown in FIGS. 1 and 4 to dry and solidify the coating, thereby forming a laminate in which multiple functional films are laminated on the cylindrical substrate.

[0030] The manufacturing apparatus 100 of the present invention may also include a rotation drive means for rotating the cylindrical substrate 111 shown in Fig. 1, a moving means for moving the coating means shown in Fig. 2 in the longitudinal direction of the substrate (Y direction in the figure), and a film thickness detection unit consisting of a film thickness sensor 151 and a sensor controller 152 shown in Fig. 3 and Fig. 4. The first and second spray nozzles and coating heads, the solidification means 141 using airflow, and the like may be linked with their respective moving means and rotating means, and the film thickness detection unit.

[0031] Figures 6(a)-(d) show each process and its interlocking. Figure 6(a) shows the first application process, in which droplets of release film material are applied to the surface of a cylindrical substrate by reciprocating motion. Figure 6(b) shows the first solidification process, in which the release film material is dried and solidified to form a release film on the surface of the cylindrical substrate. Figure 6(c) shows an example of the second application process, in which a silicone film material is applied to the surface of the release film. Figure 6(d) shows an example of the second solidification process, in which the silicone film material is dried and solidified. Figures 6(a)-(d) may be controlled by an interlocking operation controller 150 to operate the processes sequentially.

[0032] Each means of the apparatus and the formation of the coating film will be described in detail below. <Rotational drive means> The rotation drive means shown in Figure 2 includes left and right rotation central shafts 112 and 113 that support the rotation of a cylindrical substrate 111, support bases 114 and 115 that support the rotation central shafts, an actuator 116 connected to the rotation support shafts to rotate the cylindrical substrate 111, and a rotation speed controller 117 that controls the actuator and thereby the rotation speed of the cylindrical substrate 111. The rotation drive means can rotate the cylindrical substrate 111 at any rotation speed, and the rotation speed of the cylindrical substrate 111 can be set to a rotation speed suitable for coating or drying and solidifying. The rotation drive means is preferably controlled independently of the means for reciprocating or linearly moving the first spray nozzle 121a and the second spray nozzle 121b, i.e., the arrows (symbol P) in Figure 1.

[0033] <Coating means and its transportation means> The coating means shown in FIG. 3 is used in the first coating step and includes a first spray nozzle 121a that discharges the liquid release film material from a discharge hole, a first coating head 122a that supplies the coating material, a first liquid supply pump 123a, and a first coating tank 124a that stores the coating material. The coating liquid travels from the first coating tank 124a through a flow path (not shown) within the first coating head 122a and is continuously discharged at any desired rate from the discharge hole of the first spray nozzle 121a at the tip of the first coating head 122a. The method for supplying the coating material Fa to the first spray nozzle 121a is not particularly limited as long as it can discharge the coating material Fa in droplets from the spray nozzle. For example, a metering pump can be used for the first liquid supply pump 123a. Alternatively, a pressure-feeding method (not shown) can be used, in which the first coating tank 124 is pressurized and the discharge flow rate is controlled by adjusting the pressure applied. In addition, the type of the first spray nozzle 121a may be a one-fluid spray nozzle that sprays the coating material Fa in droplets by feeding it in, or a two-fluid spray nozzle that promotes the formation of droplets of the coating material Fa by supplying compressed air from a compressed air source not shown.

[0034] 4 also shows another coating means for the second spray nozzle 121b used in the second coating step. Similar to FIG. 3, this includes a second coating head 122b for supplying the silicone coating material, a second liquid pump 123b, and a second coating material tank 124b for storing the coating material. The second spray nozzle 121b at the tip of the second coating head 122b can continuously dispense coating material Fb at any desired rate from its nozzle. Similar to the coating means of FIG. 3, the method for dispensing these coating materials is not limited to a specific method. Furthermore, the shape of the second spray nozzle 121b and the method for dispensing the coating material may be different from those of the coating means of FIG. 3.

[0035] 2, 3, and 4 include stages 131a and 131b that support the first and second coating heads 122a and 122b, sliders 132 that move the stages, actuators 133 that drive the sliders, and controllers 134 that control the actuators, and are capable of reciprocating the first spray nozzle 121a and the second spray nozzle 121b at any speed in the axial direction of the cylindrical substrate 111. Here, in the first coating step of coating a release film material, the stage 131 may have an adjustment mechanism that adjusts the distance between the spray nozzle 121a in the first coating head 122a and the cylindrical substrate 111.

[0036] Furthermore, it is preferable that the moving means for the first spray nozzle 121a shown in Fig. 3 and the moving means for the second spray nozzle 121b shown in Fig. 4 can be moved and controlled independently, but they may share the same moving means. In the coating operation, the substrate is rotated by the rotation drive means while the spray nozzle 121 is moved back and forth by these moving means, whereby droplets continuously ejected from the spray nozzle 121 are applied in layers onto the circumferential surface of the cylindrical substrate, and a coating film is layered over the entire width of the substrate until the measurement value of the film thickness sensor 151 reaches a set value, thereby forming a coating film of the desired thickness on the circumferential surface.

[0037] 2 may be a controller that stores a program for inputting position information of the moving means and executing a predetermined scan based on a determiner that determines the return position of the reciprocating movement in conjunction with the moving means of the coating means, and the position information of the moving means. When it is desired to change the film thickness, for example, to thin the film thickness at a specific location such as the end of a cylindrical substrate, this interlocking operation controller 150 can control each parameter related to film formation based on the set position information of the moving means, such as by changing the return position of the reciprocating movement.

[0038] <Solidification method for drying and solidifying the coating film> Fig. 3 is a schematic diagram of a cylindrical substrate viewed from the side. Fig. 3 shows an airflow solidification means 141 having an outlet that discharges a slit-shaped airflow in the axial direction of the cylindrical substrate. As shown in Fig. 3, the drying and solidification means preferably maintains a certain gap in the radial direction from the circumferential surface of the cylindrical substrate.

[0039] The solidification means 141 using an airflow includes an airflow injection pressure controller 142 that controls the pressure of the gas being supplied, and a compressed gas supply source 143 that supplies compressed gas to the pressure controller, and can continuously inject an airflow toward the outer circumferential surface of the cylindrical substrate 111. In this case, the gas used for the airflow may be dry air or an inert gas such as nitrogen.

[0040] 3 shows solidification means 141 using an airflow, the solidification means is not limited to this. For example, a solidification method using a light irradiator can be used. However, among the solidification means of the present invention, solidification methods using high-temperature heating or hot air jets, which are used to remove solvents or harden resins, are not preferable because they increase the temperature of the base material and take time to return to room temperature.

[0041] <Film thickness detection unit> The film thickness detection unit consists of a film thickness sensor 151 and a sensor controller 152, as shown in Figures 3 and 4. The film thickness sensor 151 is installed facing the circumferential surface of the cylindrical substrate 111. It measures the film thickness of the coating film and inputs the measured values into the sensor controller 152, thereby monitoring the coating film thickness during the coating process and the drying and solidifying state of the coating film during the solidifying process. The film thickness sensor preferably measures the film thickness on the front and back surfaces of the coating film. However, the film thickness may also be calculated by measuring the surface height of the substrate and the coating film and calculating the film thickness from the change in height. The film thickness detected by the film thickness sensor 151 and the control device 152 is the average film thickness on the circumferential surface of the cylindrical substrate 111, calculated by averaging multiple measurements taken while the cylindrical substrate 111 is rotating. However, the film thickness may also be measured only at specific positions on the circumferential surface, and the measurement at that position may be used as the film thickness.

[0042] Furthermore, in the present invention, the film thickness sensor 151 uses a confocal laser sensor, but any sensor that can measure the film thickness value in the coated film state will do, and is not limited to this.

[0043] <About coating of release film material> A coating film is formed on a cylindrical substrate using the manufacturing apparatus 100 having the above configuration. A method for applying a release film material will now be described. In the coating material filling process, a coating material Fa, which is a fully degassed release film material, is placed in the first coating material tank 124a shown in FIG. 3, and the first liquid supply pump 123a pumps the coating material Fa into the first application head 122a, the first spray nozzle 121a, and the piping connecting the components. In the coating operation process, the cylindrical substrate 111 is fixed to the rotary support shafts 112 and 113 shown in FIG. 2, and then the cylindrical substrate 111 rotates at a constant rotational speed around the axis of the cylinder in the manufacturing apparatus 100. At this time, the first spray nozzle 121a, which dispenses the coating material Fa, is in a standby state at the axial end of the cylindrical substrate 111. Next, the first liquid supply pump 123a is operated, and the coating material Fa is discharged in droplets from the first spray nozzle 121a via the first coating head 122a. The coating material Fa discharged from the first spray nozzle 121a flies out in droplets and is applied so as to adhere to the circumferential surface of the rotating cylindrical substrate 111. The coating film applied in droplets to the circumferential surface of the cylindrical substrate 111 is applied to the circumferential surface of the cylindrical substrate by moving the coating head 122 back and forth in the axial direction of the cylindrical substrate 111, and is layered and applied so as to overlap, thereby forming a continuous planar coating film on the circumferential surface. In this application operation, the coating material F used is preferably one that is less diluted with solvent, i.e., one with a high solids concentration, taking into consideration the subsequent drying and solidification process. However, as the solids concentration of the coating liquid generally increases, the viscosity of the coating liquid also increases, which tends to make it more difficult for the coating means to handle. Therefore, a coating material with a viscosity adjusted to a preferred range for application is 0.03 P to 10 P, more preferably 0.1 P to 5 P. That is, in the first application step of the present invention, the viscosity of the coating liquid of the release film material discharged in droplets from the first applicator can be in the range of 0.03 P to 10 P. More preferably, the viscosity of the coating liquid of the release film material is 0.1 P to 5 P. The unit of viscosity P for the coating liquid is Poise.

[0044] Furthermore, by setting the ratio (R / M) of the movement period M [cycle / sec] in the reciprocating movement to the rotation speed R [rev / sec] of the cylindrical substrate 111 to a value that is not an integer ratio, the application position of the spray nozzle 121 on the circumferential surface of the cylindrical substrate can be dispersed, and a more uniform layered coating film can be formed. <About the drying and solidification of peeling films and silicone films> First, Figure 5 shows the configuration of an apparatus for drying and solidifying a coating film. Figure 5(a) shows a drying and solidifying means using solidifying means 141 using an airflow, and Figure 5(b) shows a configuration for solidifying a coating film using a light irradiator 151, which will be described later. Figures 5(a) and (b) are shown as representatives of the first solidifying step. The coating film in the following explanation is a coating film coated with a release film material.

[0045] First, the drying and solidifying process will be described for the configuration shown in Fig. 5(a). After the coating material F is applied to the substrate by the coating means, the substrate is rotated and an airflow is sprayed from the airflow spraying means toward the circumferential surface of the cylindrical substrate, thereby accelerating the drying of the coating film and causing it to dry and solidify.

[0046] In this drying and solidification process, it is effective to increase the temperature of the airflow by about 10 to 30°C above room temperature in order to shorten the processing time. However, if the temperature of the cylindrical substrate rises excessively after drying and solidification, thermal distortion will occur in the cylindrical substrate, which will affect the accuracy of the pattern formation in the next process. Therefore, it is preferable to perform the process at room temperature without increasing the temperature of the airflow.

[0047] Next, Figure 6 shows an example of a method for forming a laminate of a release film and a silicone film. Each step is performed in the following order: first coating step (a), first solidification step (b), second coating step (c), and second solidification step (d). After each coating step, an airflow is sprayed over the entire coating film to promote drying and solidification. Furthermore, the second coating step can be started while the cylindrical substrate is rotating during the first solidification step. This is preferable from the perspective of further enhancing adhesion by applying a silicone layer and drying the laminate together before the release film surface has completely solidified.

[0048] In this case, the cylindrical substrate is rotated in each of steps (a) to (d), but the rotation speed does not have to be the same. For example, if the coating is performed at a rotation speed of 400 rpm and then the drying and solidification is performed at a reduced speed of 25 rpm, the coating material is likely to level on the coating surface before solidification, and a high-quality coating film can be formed without leaving any droplet marks.

[0049] Another method for drying and solidifying the coating is to use a photocurable resin, which can be easily solidified at room temperature. In this case, if a photocurable resin that does not require a diluting solvent is used, there is no need to use an air jetting device. However, since a light irradiator is required to solidify the resin, it is recommended to install a light irradiator 161 and a controller 162 for controlling the irradiation time inside the device, as shown in Figure 5(b), and irradiate the substrate with light while the substrate is rotating to solidify the coating on the substrate.

[0050] <About the peel-off film> In order to reuse the cylindrical substrate used for a waterless offset master plate, after the desired printing is completed, the coating film formed on the cylindrical substrate is removed, and a coating film for a new master plate is formed on the substrate again, thereby reusing the cylindrical substrate.

[0051] In offset printing, the resist film on the substrate is removed by washing and dissolving it with a chemical solution. However, if the silicone material used in waterless lithography is removed from a cylindrical substrate using a similar method, the silicone material will adhere to the surface of the cylindrical substrate. Once adhered, the silicone material will remain in a thin layer on the surface of the cylindrical substrate. This changes the surface condition when the cylindrical substrate is reused, resulting in a decrease in the quality of the master plate.

[0052] Therefore, as a means for removing the silicone material, a release coating film (release film) is formed on the surface of the cylindrical substrate below the silicone layer, and the release film is peeled off from the cylindrical substrate together with the silicone layer in a film-like form, thereby enabling stable initialization of the cylindrical substrate.

[0053] The first function required of a release film is that it can be easily peeled from the cylindrical substrate, and to achieve this, it is preferable to use a release film material having film properties that satisfy the following formula (1): A release material having this property is determined to have easy peelability, and a release material having such peelability is called an easy peel film material.

[0054] When peeling a release film from a substrate, the forces acting on the film are the tensile force [N] that tries to peel the film off and the adhesion force [N] that tries to hold the film to the substrate. If the tensile force [N] is greater than the adhesion force [N], the film can be peeled off from the substrate.

[0055] If we transform this equation into a force balance per unit width [1 / mm], we get equation (1). Tensile strength (N / mm 2 ) × Coating thickness (mm) > Adhesion strength (N / mm) Formula (1) Tensile strength of the left item [N / mm 2 ] is the maximum tensile force [N] that can be generated without breaking the membrane, expressed as a function of the cross-sectional area of the membrane [mm 2 ], and multiplying it by the coating thickness [mm] gives the tensile force [N] per unit width [1 / mm]. Also, the adhesive strength [N / mm] on the right is the adhesion force [N] per unit width [1 / mm].

[0056] In this formula (1), the tensile strength multiplied by the coating thickness represents the film strength that can withstand peeling when the release film is removed. A force below this film strength will allow the release film to maintain its shape without tearing. The adhesive strength, also referred to as the right term, represents the resistance generated when peeling the release film from the substrate. A force greater than this resistance will allow the film to be peeled off the substrate. In other words, materials that satisfy formula (1) can be peeled off continuously from the substrate while maintaining their shape. However, materials that do not satisfy formula (1) will tear the release film during peeling, requiring significant effort to completely remove it from the substrate. Thus, whether a release film has easy peelability can be determined not only by whether the film material satisfies formula (1), but also by observing how the release film peels off the substrate.

[0057] Here, we will explain each item in formula (1). The tensile strength on the left side is the material strength of the release film material in a film state, and can be measured using a tensile tester specified in JIS B 7721 (2018). The tensile strength of the release film is 20 N / mm when it is used to hold the functional film as a master plate. 2 It is preferable that the resistance is 40N / mm or more, and furthermore, taking stability into consideration, 2 It is preferable that the thickness is equal to or more than that. Similarly, the coating thickness in the left section is the thickness of the film when it is dried and solidified as a release film, and the thicker the film, the stronger the film will be. However, the thicker the film, the longer it takes to dry and solidify, and the higher the material costs, so an appropriate film thickness is required. The thickness of this release film is preferably 100 μm or less, and more preferably 50 μm or less in order to dry and solidify in a short time.

[0058] The adhesive strength is measured based on the 90-degree peel adhesive strength measurement method described in JIS Z 0237 (2009), with the substrate having the same surface roughness as the finished surface of the cylindrical substrate. Here, the surface condition of the cylindrical substrate in this disclosure is aluminum (A5052) as the base material, and the average roughness of the finished surface is Ra 1.6.

[0059] Furthermore, according to the relationship in formula (1), the smaller the adhesive strength of the release film, the greater the tendency for it to be easily peeled, but on the other hand, the ability to retain the functional film on the cylindrical substrate during printing decreases. Therefore, while it is desirable to have a large adhesive strength within the conditions that satisfy formula (1), when considering the ease of manual peeling with fingers, an adhesive strength value of 0.50 N / mm or less is preferable, and 0.10 N / mm or less is even more preferable.

[0060] In addition, in order to maintain high coverage of such a peelable release film on the peripheral surface of a cylindrical substrate, it is important not to create a peel start point. For example, when forming a liquid film of a release film on the surface of a cylindrical substrate, if a coating method is used in which the application start point and the directionality of the coating film are clear, the coating history will remain on the formed film surface, and points that can become peel start points will easily occur. On the other hand, by using a coating method in which the coating material is dispersed in droplets and layered, it is possible to form a coating film that is less likely to have continuous peel start points, and the coating retention of the release film can be improved.

[0061] <About the production of waterless offset master plates> When manufacturing a waterless offset master plate using a cylindrical substrate with the coating method and manufacturing apparatus of the present invention, a release film is formed on the surface of the substrate in a first coating step and a first solidification step, and then a silicone layer is formed on the release film in a second coating step and a second solidification step.

[0062] More specifically, in the first coating step, a coating film is formed on the cylindrical substrate while the cylindrical substrate is rotating, with the amount of release film material calculated from the film thickness after drying and solidification. During this coating, the coating material is dispensed from the applicator in droplets and dispersed onto the cylindrical substrate, thereby forming a uniform liquid film on the circumferential surface of the cylindrical substrate. For example, if the rotation of the cylindrical substrate is stopped midway, the coating material will flow due to the influence of gravity, resulting in an uneven coating film. Therefore, it is preferable to maintain the rotation of the cylindrical substrate from the start to the end of coating. If coating is performed discontinuously during coating, the coating film will dry and solidify in a separated state, and when the coating liquid combines in the discontinuous areas to form a coating film, it will be difficult to maintain sufficient strength.

[0063] Next, in the first coating step, when the coating thickness of the release film reaches the set thickness as measured by the film thickness sensor, the first coating step is terminated, and the first solidification step is performed while maintaining the cylindrical substrate in a rotating state to prevent the liquid film from losing its shape. In the first solidification step, room temperature air is blown onto the coating surface to promote drying, and at the same time, the liquid film shrinks and solidifies, solidifying the release film so that it grips the cylindrical substrate. In this case, in addition to air blowing, the liquid film can also be solidified by using a photocurable resin as the release film material and then irradiating it with light. Resin curing by light irradiation has the advantage of minimizing the temperature rise of the substrate and also has the advantage of completing the solidification step in a short time.

[0064] Next, the first solidification process is terminated by determining the dryness state based on the film thickness sensor measurement value, and then the process proceeds to the second coating process, where silicone material is applied. The transition from the first solidification process to the second coating process can be carried out after the release film has completely solidified in the first solidification process. However, by transitioning before the release film surface has completely solidified, the master production time can be shortened and the adhesion between the release film and the silicone layer can be further improved. Furthermore, the release film is dried and solidified by further drying in the second solidification process. After the second coating process is completed, the second solidification process can be carried out to produce a waterless offset master having a laminate of a release film and a silicone film on a cylindrical substrate.

[0065] The waterless offset plate blank manufactured in this manner has a release film portion formed as a uniform coating on the peripheral surface of the cylindrical substrate, which makes it less likely for the release film to peel off during printing and results in high film coating retention.

[0066] Furthermore, when reusing the cylindrical substrate, since the release film is made of an easily peelable material, by scratching part of the film surface with a cutter or the like to create a starting point for peeling, the release film can be easily peeled off by hand from the cylindrical substrate together with the silicone layer.

[0067] Furthermore, the functional film of the waterless offset master plate of the present invention has been described as having a two-layer structure consisting of a release film and a silicone layer, but other than these two layers, for example, a heat-sensitive layer for forming a printing pattern between the release layer and the silicone layer may be provided, or a protective film that can be easily peeled off may be provided on the outside of the silicone layer. In this case, just as with forming a silicone layer on a release film, by increasing the number of coating nozzles, coating means, and coating nozzle movement means for the coating material according to the number of coating films, a laminated film can be formed in the same manner as in the second coating step and the second solidification step. [Example]

[0068] The following describes a comparison of the performance of specific embodiments of the present invention with examples and comparative examples, but the present invention is not limited to these examples.

[0069] For Examples 1 and 2 and Comparative Example 1, evaluation samples of the master plate were prepared under each condition, and then the durability of the functional film was evaluated assuming printing, and the peelability of the release film was evaluated assuming substrate recycling.

[0070] Durability was evaluated by pressing a rubber roller, modeled after the blanket used in offset printing, against the outer surface of the master plate, and running the plate for 50 and 100 hours to check whether the functional film could maintain its coating on the cylindrical substrate. Evaluations were made to check for lifting or peeling of the release film from the substrate, and peeling of the silicone film from the release film, and the conditions were checked visually. The evaluation criteria were as follows: if no change in the condition of the functional film occurred after the set durability time (50 hours, 100 hours), it was rated as "Good: ◯"; if defects such as peeling or tears were observed in the functional film, it was rated as "Poor: ×"; and if lifting of the functional film, which is a precursor to defects but does not reach the "X" rating, was observed, it was rated as "Slightly Poor: △".

[0071] Peelability was evaluated by manually removing the release film from the substrate, by making a cut at the end of the functional film on the cylindrical substrate and peeling it circumferentially from there to peel the laminate of the release film and silicone film from the cylindrical substrate. Peelability was evaluated as "good: ◯" if the laminate could be easily peeled off without breaking, "poor: ×" if the laminate was torn in three or more places and peeling was difficult, and "fair: △" if the laminate could be peeled off but was torn in two or less places and was difficult to peel off.

[0072] Example 1 Using a manufacturing apparatus similar to that shown in Figures 1-4, a laminate of a release film and a silicone film was formed on a cylindrical substrate using the procedure shown in Figure 6. A cylindrical substrate with an outer diameter of 185 mm and an axial length of 300 mm was used. In the first coating step, the amount of coating material applied was set so that when a uniformly flat coating film was formed on the cylindrical substrate's surface, the film thickness after drying and solidification would be 100 μm. For the first coating step, a single-fluid spray nozzle was used to apply the release film material to the substrate, rotating it at 390 rpm (6.5 rev / sec) with a reciprocating cycle of 12.5 sec (0.08 cycle / sec). In the subsequent solidification step, the substrate rotation speed was reduced to 25 rpm, and a slit-type air nozzle was used to spray an airflow at a discharge velocity of 90 m / sec for 10 minutes while maintaining the substrate rotation speed at 25 rpm, allowing the coating to dry and solidify. In the second coating step, the rotation speed of the substrate was increased to 390 rpm, and the silicone film material was applied dropwise using a spray nozzle, as in the first coating step, to a thickness of 10 μm after drying. In the second solidification step, the rotation speed of the substrate was reduced to 25 rpm, and using the same slit-type air nozzle as used in drying the release film, an airflow with a discharge velocity of 90 m / sec was sprayed for 10 minutes while the rotation speed of the substrate was maintained at 25 rpm, drying and solidifying the coating.

[0073] The results of confirming the durability of the functional film and the releasability of the release film are shown in Table 1. In the durability confirmation, in Examples 1 and 2, no problems occurred with lifting or peeling of the release film or peeling of the silicone film even after 100 hours had passed.

[0074] The release film material was made from polyurethane and diluted with N,N-dimethylformamide as the main solvent, with a solid content of 10 wt%. The viscosity of the diluted liquid material was 1P, and the adhesive strength of the film after drying and solidification was 0.10 N / mm, while the tensile strength was 40 N / mm. 2 The film had a thickness of 100 μm and was easily peelable.

[0075] [Table 1]

[0076] <Example 2> In the first solidification step, a manufacturing apparatus with the configuration shown in Figures 1 to 4, with the addition of the light irradiator shown in Figure 5(b), was used. A photo-curable coating material was used as the release film material to form a release film and a silicone film on a cylindrical substrate. In the first coating step, a cylindrical substrate with an outer diameter of 185 mm and an axial length of 300 mm was used. When a uniformly flat coating film was formed on the circumferential surface of the cylindrical substrate, the layered film thickness was set to 50 μm after solidification. Using the same one-fluid spray nozzle as in Example 1, the substrate was rotated at 390 rpm (6.5 rev / sec), and the release film material was layered and applied with a reciprocating cycle of 12.5 sec (0.08 cycle / sec). Next, in the first solidification step, the rotation speed of the substrate was reduced to 25 rpm, and the irradiation light intensity was 300 mW / cm. 2 Using a light irradiator, light irradiation was continued for 10 minutes while the substrate rotation speed was maintained at 25 rpm, and the coating film was solidified. Next, in the second coating process, the substrate rotation speed was increased again to 400 rpm, and the coating film thickness was set so that the film would be 10 μm after drying and solidification. The silicone material was applied using the same one-fluid spray nozzle as in the first coating process. Next, in the second solidification process, the substrate rotation speed was reduced to 25 rpm, and a slit-type air nozzle was used to spray an airflow at a discharge velocity of 90 m / sec for 10 minutes while the substrate rotation speed was maintained at 25 rpm, drying and solidifying the coating film, producing a master plate with a base release layer and an upper silicone film. The release film material is a photo-curing resin made from polyurethane. When the material solidifies, the shrinkage rate is 10%, the liquid viscosity is 5P, and the adhesive strength in the film state is 0.08N / mm, while the tensile strength is 40N / mm. 2 It is easily peelable with a film thickness of 100 μm. <Comparative Example 1> In Example 1, the coating amount adjustment means for the first coating step was changed from thickness setting using a film thickness sensor to adjusting the liquid amount using a liquid feed pump.The same one-fluid spray nozzle as in Example 1 was used, and while the substrate was rotated at 390 rpm (6.5 rev / sec), the nozzle was moved only once in one direction to apply the coating in a spiral pattern over the entire circumferential surface of the substrate, at a nozzle movement speed of 5 mm / sec.As in Example 1, the release film material was applied so that the film thickness after drying and solidifying would be 100 μm.

[0077] The durability of the functional film and the releasability of the release film were confirmed using waterless offset master plates manufactured under the conditions of Examples 1 and 2 and Comparative Example 1. The results are shown below. To confirm durability, each master plate was set in a test machine capable of rotating and holding the plate. While held at a rotation speed of 200 rpm, a rubber roller was pressed against the plate surface with a load of 10 kg. The plate surface condition was visually confirmed after 50 and 100 hours. In Examples 1 and 2, no problems occurred with lifting or peeling of the release film or peeling of the silicone film even after 100 hours. On the other hand, in Comparative Example 1, although no peeling of the silicone film occurred, lifting of the film occurred over time in some areas where the release film application began, and before 100 hours had passed, the functional film broke from the lifting and peeled off from the substrate.

[0078] To check the peelability, a cut was made in the functional film of the master plate with a cutter to partially break the release film, and the functional film was then pulled with fingers from that point to check whether the release film could be easily peeled off. The results of checking the durability of the functional film and the releaseability of the release film are shown below. In the peelability check, the release film could be peeled off by hand under all conditions, but in Comparative Example 1, the film was easily torn during peeling. [Explanation of symbols]

[0079] 100: Waterless offset master manufacturing equipment 110: Rotation drive means 111: Cylindrical base material 112, 113: Rotation axis 114, 115: Support stand 116: Actuator 117: Rotation speed controller 121a: First spray nozzle 121b: Second spray nozzle 122a: First application head 122b: Second application head 123a: First liquid delivery pump 123b: Second liquid delivery pump 124a: First paint tank 125b: Second paint tank 131a: First applicator stage 131b: Second applicator stage 132: Slider 133: Actuator 134: Controller for controlling movement of application means 141: Air flow solidification method 142: Air jet pressure controller 143: Compressed gas supply source 150: Interlocking operation controller 151: Film thickness sensor 152: Sensor controller 160: Light irradiator 161: Controller for controlling irradiation time F:Painting material Fa: Coating material for the first coating process Fb: Coating material for the second coating process R: Rotation direction P: Reciprocating direction

Claims

1. A method for manufacturing a waterless offset master plate, comprising: a first coating step of coating a liquid release film material on a surface of a cylindrical substrate; a first solidification step of drying and solidifying the release film material to form a release film on the surface of the cylindrical substrate; a second coating step of coating a silicone film material on the surface of the release film; and a second solidification step of drying and solidifying the silicone film material, The release film material has a standard release characteristic after drying and solidification, and when the coating film thickness is 100 μm or less, the tensile strength of the release film [N / mm ２ ] and the coating thickness [mm] product is used a release film material that exceeds the adhesive strength [N / mm] of the release film, the first coating step is a coating step of discharging the release film material in droplets from a first applicator onto the circumferential surface of the cylindrical substrate while rotating the cylindrical substrate about its axis as a central axis, and then moving the first applicator back and forth in the axial direction of the cylindrical substrate while spraying the release film material in droplets onto the surface of the cylindrical substrate, thereby laminating the release film material and forming a coating film; the first solidification step is a step of drying and solidifying the applied release film material while rotating the cylindrical substrate following the first application step, thereby solidifying the applied release film material on the cylindrical substrate and forming the release film on the cylindrical substrate; the second coating step is a step of discharging the silicone film material from a second applicator and coating the silicone film material on the surface of the release film; A method for producing a waterless offset master plate, in which a laminate including at least the release film and a silicone film is formed on the surface of a cylindrical substrate.

2. 2. The method for producing a waterless offset master plate according to claim 1, wherein the second coating step is started in the middle of the first solidifying step while the cylindrical substrate is being rotated.

3. 3. The method for producing a waterless offset master plate according to claim 1, wherein the first solidification step and the second solidification step are carried out by using air generated by the rotation of the cylindrical substrate or by blowing air from an air nozzle onto the coating surface on the cylindrical substrate.

4. 3. The method for manufacturing a waterless offset master plate according to claim 1, wherein a photocurable resin is used as the release film material, and after the release film material is applied, the substrate is rotated and irradiated with light to solidify the release film material.

5. a first coating means having a first spray nozzle for applying a first coating material to the peripheral surface of the cylindrical substrate; and a second coating means having a second spray nozzle for applying a second coating material to the peripheral surface of the cylindrical substrate; a rotation drive means for rotating the cylindrical substrate about the axis of the cylinder; a solidification means for solidifying the coating film applied to the peripheral surface of the cylindrical substrate by blowing air from an air nozzle or irradiating light; The apparatus includes at least a measuring device for measuring a film thickness value of a coating film, and a controller for switching between the first and second coating means and the solidifying means, The first and second application means are provided with a moving means for repeatedly moving the first spray nozzle and the second spray nozzle back and forth in the direction of the rotation axis of the cylindrical substrate, and further, the coating material is applied by moving the first and second spray nozzles by the moving means while the cylindrical substrate is rotated by the rotation driving means, and The apparatus for manufacturing a waterless offset master plate, wherein the second coating means starts a coating process by the second coating means after stopping the solidifying means based on the measurement value of the measuring instrument.

Images