Method and apparatus for evaluating ink adhesion

Abstract

The present invention provides an ink adhesion evaluation method and apparatus for evaluating the adhesion of a substrate to a printing cylinder without using the printing press itself. [Solution] An ink adhesion evaluation method for evaluating the adhesion of a substrate to a printing plate 70 when ink is spread on a printing plate 60 using an ink spreading machine and printed on the substrate 70, comprising: an ink spreading step in which the printing plate 60 is fixed on a base 10 of the ink spreading machine and ink is spread on the printing plate with an ink spreading roll; an overlay step in which the substrate is placed on top of the ink-spread printing plate; an overlay step in which a predetermined printing pressure is applied to the substrate placed on the printing plate on the base with an ink spreading roll and left to stand for a predetermined time; and a peeling step in which the ink spreading roll is removed and the substrate is peeled off from the printing plate, and the presence or absence of adhesion of the substrate to the printing plate in the peeling step is evaluated using the standing time as a parameter and the critical standing time at which adhesion begins to occur is determined.

Description

Technical Field

[0001] The present invention relates to an ink sticking evaluation method and an ink sticking evaluation apparatus for evaluating the presence or absence of sticking of a substrate to a printing plate when ink is developed on the printing plate and printed on the substrate.

Background Art

[0002] FIG. 10 is a schematic explanatory view of a general flexographic printing machine 200. In the flexographic printing machine 200, ink is transferred from the plate cylinder 160 to the substrate 170. The ink is supplied from the ink chamber 180 to the anilox roll 150 and then transferred to the flexible plate cylinder 160 made of rubber or resin. Further, the ink is transferred from the plate cylinder 160 to the substrate 170 sandwiched between the plate cylinder 160 and the impression cylinder 190, thereby completing the printing on the substrate 170. In FIG. 10, there is only one plate cylinder 160 around the impression cylinder 190, but in the case of multicolor printing, there are as many plate cylinders 160 as the number of colors around the impression cylinder 190. In the flexographic printing machine 200, the printing pressure is adjusted by adjusting the distance between the centers of the plate cylinder 160 and the impression cylinder 190.

[0003] The following patents have been filed regarding an evaluation apparatus and an evaluation method for ink when ink is developed on a printing plate and printed on a substrate. For example, Patent Document 1 (Japanese Unexamined Patent Application Publication No. 2006-0,88354) discloses a printing plate material excellent in transportability in a plate-making apparatus and excellent in printing suitability, a printing plate using the same, and a printing method.

[0004] The printing plate described in Patent Document 1 is a printing plate material having an image forming functional layer on one surface of a polyester support and a conductive layer containing a conductive substance on the other surface, wherein the conductive substance is tin oxide, and a back coat layer is provided on the conductive layer, and the conductive layer and the back coat layer each contain a polyester resin, an acrylic resin or a cellulose ester resin. Further, Patent Document 1 also describes an evaluation method and evaluation results for sticking to the plate cylinder of a printing machine.

[0005] Patent document 2 (Japanese Patent Publication No. 05-057878) discloses an apparatus for efficiently conducting tests in paper printability tests.

[0006] The printability testing apparatus described in Patent Document 2 is characterized by being equipped with an ink uniform quantitative supply device that supplies ink uniformly in the width direction to the ink mixing roll. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2006-088354 [Patent Document 2] Japanese Patent Application Publication No. 05-057878 [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] The present invention provides an evaluation method for evaluating ink adhesion that may occur in offset printing presses, flexographic printing presses, letterpress printing presses, and letterpress printing presses (hereinafter also referred to as the actual machine or printing press body), and is preferably usable as an ink adhesion evaluation method for flexographic printing presses.

[0009] In the flexographic printing described above, during normal printing, the plate cylinder 160 and impression cylinder 190 rotate continuously, and the substrate 170 passes continuously through the plate cylinder, so the substrate 170 does not stick to the plate cylinder 160.

[0010] However, at the start of printing, it is necessary to print on the substrate 170 using a flexographic printing press 200 equipped with a printing cylinder 160 to check the color (color proof). In this case, the rotation of the printing cylinder 160 and impression cylinder 190 is stopped at the start of printing to check the color, so the substrate 170 remains in close contact with the printing cylinder 160 for about 5 minutes. During the color check, depending on the performance of the ink, the ink may soak into the substrate 170 or the printing cylinder 160, causing the substrate 170 to stick to the printing cylinder 160 (hereinafter referred to as substrate sticking).

[0011] This adhesion to the substrate depends on the performance of the ink, that is, how easily the ink penetrates the substrate 170 or the printing cylinder 160. However, it also varies depending on the pressure between the ink-covered substrate 170 and the printing cylinder 160 (hereinafter also referred to as printing pressure), and the amount of time the substrate 170 remains in close contact with the printing cylinder 160 (hereinafter also referred to as the resting time), making quantitative evaluation difficult. The tack value (viscosity of the ink) is thought to be related to the performance of the ink, but this is not clear. Therefore, it is necessary to evaluate the presence or absence of substrate adhesion for each ink individually.

[0012] Furthermore, when evaluating the adhesion of the substrate 170 to the plate cylinder 160 using the printing press itself, if the substrate 170 adheres to the plate cylinder 160, the plate cylinder 160 must be replaced, which presents significant challenges in terms of time and cost. Therefore, an ink adhesion evaluation device is needed that can evaluate whether or not the substrate adheres to the printing press itself for each ink, without using the printing press itself.

[0013] Patent Document 1 describes a method for evaluating adhesion to the printing cylinder, stating that "the process of printing 100 sheets and removing the printing plate was repeated 10 times, and the number of times the plate adhered was evaluated in the following ranks as an indicator of the ease of mounting to the printing press." The evaluation results for adhesion to the printing cylinder are described as "A: No adhesion to the printing cylinder, B: Adhesion to the printing cylinder less than 3 times, C: Adhesion to the printing cylinder 3 times or more." This is because the phenomenon of adhesion to the printing cylinder is unstable and difficult to reproduce.

[0014] Patent Document 2 provides a printability testing apparatus that enables simple and rational printing without individual differences by providing an ink uniform quantitative supply device that supplies ink uniformly in the width direction to the ink mixing roll. However, Patent Document 2 does not describe a method for evaluating the adhesion of the substrate to the printing cylinder.

[0015] Traditionally, when performing color matching on the printing press itself (the actual machine on the production line), a problem occurred where, upon temporarily stopping the press to check the color tone and then restarting it, the substrate (printing paper) would stick to the printing plate and peel off, leaving some of the substrate inside the printing press. In such cases, the printing press had to be disassembled, the inside cleaned, and various adjustments redone, which had a significant impact on the production line. In particular, in recent years, due to increased environmental awareness, the negative list has been updated and some ink components have been changed. This slight change in ink properties has made the printing press more susceptible to problems caused by substrate peeling.

[0016] In view of the above problems, the main object of the present invention is to provide an ink adhesion evaluation method and an ink adhesion evaluation apparatus that can evaluate whether or not a substrate adheres to the plate cylinder for each ink more easily and reliably without using the printing press itself. More specifically, the present invention is to provide an ink adhesion evaluation method and an ink adhesion evaluation apparatus that evaluates whether or not a substrate adheres to the plate cylinder for each ink using a color spreading machine used to create color spreading samples, and evaluates how difficult it is for each ink to adhere, or under what conditions the ink should be used in the printing press to ensure that the substrate does not adhere.

[0017] The present invention relates to an evaluation method for evaluating ink adhesion that may occur in offset printing presses, flexographic printing presses, letterpress printing presses, and letterpress printing presses (hereinafter also referred to as the actual machine or printing press body), and is preferably usable as an ink adhesion evaluation method for flexographic printing presses. [Means for solving the problem]

[0018] (1) The ink adhesion evaluation method, which follows a single plane, is an ink adhesion evaluation method that evaluates the adhesion of a substrate to a printing plate when ink is spread on a printing plate and printed on a substrate using a color spreading machine, and comprises: a spreading step in which the printing plate is fixed on the base of the color spreading machine and ink is spread on the printing plate with a spreading roll; a superposition step in which a substrate is placed on top of the ink-spread printing plate; a printing pressure setting step in which a predetermined printing pressure is applied to the substrate placed on the printing plate on the base with a spreading roll and it is left to stand for a predetermined time; and a peeling step in which the spreading roll is removed and the substrate is peeled off from the printing plate, and the presence or absence of adhesion of the substrate to the printing plate in the peeling step is evaluated using the setting time as a parameter, and the critical setting time at which adhesion begins to occur is determined.

[0019] Whether or not the substrate adheres to the plate cylinder in a printing press is determined by the performance of the ink, the printing pressure between the plate cylinder and the substrate when the ink is transferred to the plate cylinder, and the time it is left to stand under that pressure. Therefore, by placing the substrate on top of a printing plate with the ink spread on it, applying the same printing pressure as the impression cylinder of the printing press, and letting it stand for a time equivalent to the time required to check the color, it is possible to reproduce whether or not the substrate adheres to the plate cylinder in a printing press.

[0020] However, around the settling time at which adhesion begins to occur (critical settling time), the reproducibility of whether or not the substrate adheres to the printing plate is poor. Therefore, in the ink adhesion evaluation method with the above configuration, the critical settling time is determined, and the presence or absence of adhesion of the substrate to the plate cylinder in the printing press is evaluated based on whether the critical settling time is sufficiently longer than the time required to check the color tone, etc.

[0021] (2) The ink sticking evaluation method according to the second invention is an ink sticking evaluation method following one aspect. In the color development step, it includes the step of rotating a color development roll coated with ink on a printing plate for color development. The printing pressure standing step includes the step of adjusting the printing pressure by a pressure adjustment mechanism of a color developing machine. The measurement of the printing pressure may be performed using a pressure measurement film.

[0022] A color developing machine usually rotates a color development roll uniformly coated with ink on a substrate for color development and is used to create a color development sample. However, in the ink sticking evaluation method with the above configuration, the color developing machine is used for the purpose of developing ink on a printing plate. By doing so, a printing plate in a state close to the plate cylinder on which the ink of the printing press main body has been developed can be created. In this case, it is desirable to use the same printing plate as the one used in the printing press main body.

[0023] Since the color developing machine is equipped with a pressure adjustment mechanism for adjusting the printing pressure during color development sample creation, this can be used for adjusting the printing pressure of the roll during standing. Here, the dial value of the pressure adjustment mechanism adjusts the distance between the base and the color development roll. If the total thickness of the printing plate and the substrate inserted between the base and the color development roll is different, the printing pressure will be different even with the same dial value. Therefore, in the ink sticking evaluation method according to the present invention, the printing pressure is measured using a pressure measurement film (also referred to as a press scale or a presheet).

[0024] (3) The ink sticking evaluation method according to the third invention is an ink sticking evaluation method following one aspect or the second invention. Further, when printing using each ink in the printing press main body, the critical standing time is measured, and the correlation of the critical standing time between the ink sticking evaluation method using a color developing machine and the ink sticking evaluation method using the printing press main body is obtained. The critical standing time in the ink sticking evaluation method using a color developing machine required to prevent the substrate from sticking to the plate cylinder of the printing press main body may be obtained.

[0025] As described above, whether or not the substrate adheres to the plate cylinder in the printing press is determined by the performance of the ink, the printing pressure between the plate cylinder and the substrate when the ink is transferred to the plate cylinder, and the settling time during the printing pressure setting period. However, while the printing plate of a color spreader is flat, the plate cylinder of the printing press itself may be cylindrical. As a result, there may be differences in how the ink adheres between the color spreader and the printing press. In this regard, with the above configuration, in order to determine whether the substrate will adhere to the plate cylinder of the printing press at a predetermined printing pressure and resting time when using a certain ink, the adhesion of the ink to the printing press can be predicted with high accuracy by determining the correlation between the critical resting time in the printing press and the critical resting time in the color spreader at a predetermined printing pressure.

[0026] (4) The ink adhesion evaluation device, which follows other parameters, comprises a base that can move in parallel, an ink spreading roll for spreading ink, a pressure roll that supports the base from below, a pressure adjustment mechanism for adjusting the printing pressure of the ink spreading roll on the base, a printing plate that is removablely fixed on the base, and a pressure measuring film. The ink spreading roll spreads ink on the printing plate and applies a predetermined printing pressure for a predetermined time to a substrate placed on top of the ink-spread printing plate, peels the substrate, to which the predetermined pressure has been applied for a predetermined time, from the printing plate, and evaluates the adhesion of the substrate to the printing plate.

[0027] With the above configuration, by combining a printing plate and a pressure measuring film with a color spreading machine, it is possible to evaluate whether a particular ink adheres to the plate cylinder of a substrate at a specific printing pressure and a specific settling time, without using the printing press itself. As a result, using the ink adhesion evaluation device makes it possible to significantly reduce costs and time compared to performing ink adhesion evaluation on the printing press itself.

[0028] (5) The ink adhesion evaluation apparatus according to the fifth invention is an ink adhesion evaluation apparatus according to the other aspects, wherein the pressure of the pressure adjustment mechanism is set using the correlation between the set value of the pressure adjustment mechanism and the pressure measured by the pressure measuring film, the pressure measured by the pressure measuring film is measured by placing the pressure measuring film on top of the substrate placed on top of the printing plate and applying printing pressure with the pressure adjustment mechanism, and when evaluating ink adhesion, printing pressure may be applied with a thickness adjustment film of the same thickness as the pressure measuring film placed between the substrate and the color spreading roll.

[0029] The above configuration allows for more accurate evaluation of ink adhesion. [Effects of the Invention]

[0030] According to the ink adhesion evaluation method of the present invention, it is possible to easily and reliably evaluate whether or not a substrate adheres to the plate cylinder with respect to a given ink, without using the printing press itself. [Brief explanation of the drawing]

[0031] [Figure 1] This is a schematic perspective view showing an example of the configuration of an ink adhesion evaluation device. [Figure 2] This is a schematic diagram illustrating an example of the configuration of an ink adhesion evaluation device. [Figure 3] Figure 3(a) is a schematic diagram showing an example of the operation of the color development step, Figure 3(b) is a schematic diagram showing an example of the operation of the overlapping step, Figure 3(c) is a schematic diagram showing an example of the operation of the printing pressure setting step, Figure 3(d) is a schematic diagram showing an example of the operation of the peeling step, and Figure 3(e) is a schematic diagram showing an example of the operation of the printing pressure measurement step. [Figure 4] This graph shows an example of the correlation between the value of the dial gauge of the pressure adjustment mechanism and the measurement value of the pressure measuring film. [Figure 5] This is a photograph of a printed plate showing the state (△) where the substrate has partially begun to adhere during the peeling step. [Figure 6]This is a photograph of a printed plate showing a state (×) where the adhesive area of ​​the substrate has increased during the peeling step. [Figure 7] This figure shows the evaluation results of ink A's adhesion, with printing pressure and resting time as parameters. [Figure 8] This figure shows the evaluation results of ink B's adhesion, with printing pressure and resting time as parameters. [Figure 9] This figure shows the evaluation results of ink C adhesion, with printing pressure and resting time as parameters. [Figure 10] This is a schematic diagram illustrating a flexographic printing press. [Modes for carrying out the invention]

[0032] Embodiments of the present invention will be described below with reference to the drawings. In the following description, identical parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed descriptions of them will not be repeated.

[0033] (Configuration of the ink adhesion evaluation device) Figure 1 is a schematic perspective view showing an example of the configuration of the ink adhesion evaluation device 100, and Figure 2 is a schematic explanatory diagram showing an example of the configuration of the ink adhesion evaluation device 100.

[0034] In Figures 1 and 2, the ink adhesion evaluation device 100 comprises a base 10, a pressure roll 20, a pressure adjustment mechanism 30, a rubber roll 40, and a metal roll 50 (however, the pressure roll 20 and pressure adjustment mechanism 30 are not shown in Figure 1). The pressure adjustment mechanism 30 is normally installed on the pressure roll 20 and adjusts the printing pressure of the rubber roll 40 by changing the distance between the pressure roll 20 and the rubber roll 40 by adjusting the height of the pressure roll 20 up and down.

[0035] The base 10 moves horizontally due to the rotation of the pressure roll 20 and the rubber roll 40, and the rubber roll 40 and the metal roll 50 rotate in opposite directions to spread the ink (see Figure 3). Of the components of the ink adhesion evaluation device 100, the base 10, pressure roll 20, pressure adjustment mechanism 30, rubber roll 40, and metal roll 50 may be the same as those of a normal ink spreading machine. However, the ink adhesion evaluation device 100 further includes a printing plate 60 and a pressure measuring film 80. The rubber roll 40 and the metal roll 50 together constitute an ink spreading roll that spreads the ink.

[0036] (Conceptual approach to the configuration of the ink adhesion evaluation device 100) The adhesion of the substrate 170 to the plate cylinder 160 can be evaluated by stopping the rotation of the plate cylinder 160 and other components of the flexographic printing press 200 for a predetermined time, and then checking whether the substrate 170 is still adhering to the plate cylinder 160. However, when evaluating the adhesion of the substrate 170 to the plate cylinder 160 using a flexographic printing press 200, there are significant challenges in terms of time and cost, such as the need to replace the plate cylinder 160 if the substrate 170 adheres to it. Therefore, there was a need for an ink adhesion evaluation device 100 that could evaluate whether the substrate 170 adheres to the plate cylinder 160 without using a flexographic printing press 200, by leaving the substrate 170 on the plate cylinder 160, which has been colored with a specific ink, at a specific printing pressure for a specific time.

[0037] This ink adhesion evaluation device 100 is as follows: (A) The printing plate 60 can be colored with ink in the same way as the printing press 200. (B) The printing plate 60 on which the ink has been spread can be placed over the substrate 70, and the required printing pressure can be applied from above (the printing pressure can be adjusted). (C) It is necessary to be able to accurately set or measure the printing pressure to be applied.

[0038] The inventors have found that (A) above uses a color spreading machine to spread ink onto a substrate for color proofing, and that by placing a printing plate 60 on the base 10 instead of the substrate 70 and rotating the pressure roll 20 and rubber roll 40, the ink can be spread onto the printing plate 60. The above (B) is that the substrate 70 is placed on top of the ink-distributed printing plate 60, positioned under the rubber roll 40, and the required printing pressure can be applied by using a pressure adjustment mechanism 30 that adjusts the printing pressure of the rubber roll 40. Furthermore, (C) above found that by placing a pressure measuring film 80 on top of the substrate 70 on the printing plate 60, setting the dial value of the pressure adjustment mechanism 30 to a predetermined value, placing the rubber roll 40 on the pressure measuring film 80 to measure the printing pressure, and correlating the dial value of the pressure adjustment mechanism 30 with the pressure measurement value of the pressure measuring film 80, the printing pressure can be accurately set.

[0039] The operation of each step of the ink adhesion evaluation method using the ink adhesion evaluation device 100 will be explained below with reference to Figures 3(a) to (e). Figure 3(a) is a schematic diagram showing an example of the operation of the color development step, Figure 3(b) is a schematic diagram showing an example of the operation of the overlapping step, Figure 3(c) is a schematic diagram showing an example of the operation of the printing pressure setting step, Figure 3(d) is a schematic diagram showing an example of the operation of the peeling step, and Figure 3(e) is a schematic diagram showing an example of the operation of the printing pressure measurement step.

[0040] (Color development step) In the color spreading step, first, an appropriate amount of ink is applied to the rubber roll 40, and the ink is spread evenly by rotating the rubber roll 40 and the metal roll 50. Next, the printing plate 60 to be used in the printing press is fixed onto the base 10, and the rubber roll 40 and metal roll 50 are moved downward and brought into contact with the base 10 with the appropriate printing pressure P applied. Furthermore, the rotation of the pressure roll 20 and the rubber roll 40 causes the base 10 to move horizontally, and the ink from the rubber roll 40 is spread onto the printing plate 60.

[0041] (Overlay step) In the overlapping step, first the rubber roll 40 and the metal roll 50 are moved upward, and then the colored printing plate 60 is moved below the rubber roll 40. Next, the base material 70 (printing paper) is placed on top of the printing plate 60. In the printing pressure measurement step described later, the base material 70 and the pressure measurement film 80 are placed on top of the printing plate 60, so in the overlapping step and the printing pressure setting step, a thickness adjustment film 75 with the same thickness as the pressure measurement film 80 is placed on top of the base material 70. The pressure measurement film 80 used in this embodiment had a total thickness of 162 μm.

[0042] (Print pressure setting step) In the printing pressure setting step, the substrate 70 and thickness adjustment film 75 are placed on top of the printing plate 60, the rubber roll 40 and metal roll 50 are lowered on top of them, a predetermined printing pressure Px is applied, and the plate is left to stand for a predetermined time. In this embodiment, the presence or absence of adhesion was evaluated using the standing time as a parameter, with a standard standing time of 5 minutes as the center, but shorter standing times were used for inks that adhere easily, and longer standing times for inks that do not adhere easily. Furthermore, the printing pressure Px was also evaluated using the printing pressure Px before and after the standard printing pressure of the printing press itself.

[0043] (Separation step) In the peeling step, first, the rubber roll 40 and metal roll 50 are moved upward, the thickness adjustment film 75 is removed, and then the base material 70 is peeled off from the printing plate 60. If no base material 70 remains on the printing plate 60 after peeling off the base material 70, it is considered not to be stuck; if even a small amount of base material 70 remains, it is considered to be stuck. Note that whether or not adhesion occurs may also depend on the direction in which the substrate 70 is peeled off. In this embodiment, the substrate was peeled off in the 180° direction, which is more likely to cause adhesion. (The end of the substrate was pulled towards the opposite end to peel it off.)

[0044] (Print pressure measurement step) Typically, a printing press is equipped with a pressure adjustment mechanism 30 (dial gauge) to change the printing pressure by adjusting the distance between the rubber roll 40 and the pressure roll 20. However, since the pressure adjustment mechanism 30 displays distance rather than the printing pressure itself, when the printing plate 60 and substrate 70 are inserted between the rubber roll 40 and the base 10, as in the printing pressure setting step, the printing pressure will be higher for the same distance compared to when only the substrate 70 is inserted, as in the case of using it as a color spreading machine. Furthermore, the setting value (dial gauge value) of the pressure adjustment mechanism 30 cannot be used when comparing printing pressure between the ink adhesion evaluation device 100 and the printing press body. Therefore, in this embodiment, the printing pressure during the printing pressure setting step is measured using the pressure measuring film 80.

[0045] In the printing pressure measurement step, the correlation between the value of the dial gauge of the pressure adjustment mechanism 30 and the pressure measurement value of the pressure measurement film 80 is measured with the substrate 70 and pressure measurement film 80 stacked on top of the printing plate 60. The pressure measuring film 80 is not particularly limited, but for example, Fujifilm's "Prescale" can be used. With "Prescale," the value of the applied pressure can be measured depending on the type of Prescale and the M concentration after pressure is applied. Furthermore, the pressure measurement film 80 is composed of a set of two sheets of Prescale, and since a coloring agent layer is provided on the inner surface of the two PET-based supports, even if ink spreads from the rubber roll 40 to the outside of the pressure measurement film 80, it does not interfere with the measurement of the M density of the inner coloring agent layer.

[0046] Figure 4 shows a correlation graph between the dial gauge value of the pressure adjustment mechanism 30 and the pressure measurement value (M density) of the pressure measuring film 80. As the printing pressure dial value increases and the distance between the base 10 and the rubber roll 40 decreases, the printing pressure increases rapidly and the M density increases. As shown in Figure 5, in the printing pressure setting step, if a thickness adjustment film 75 of the same thickness as the pressure measurement film 80 is placed on top of the substrate 70, the printing pressure (M density) in the printing pressure setting step can be estimated from the printing pressure dial value using the correlation graph between the printing pressure dial value and the M density shown in Figure 4. Furthermore, since the pressure measuring film 80 can also be used to measure the printing pressure of the printing press itself, the printing pressure of the printing press and the printing pressure of the ink adhesion evaluation device 100 can be correlated by using the pressure measuring film 80.

[0047] Figures 5 and 6 show photographs of the base 10 and the state of the printing plate 60 on the base 10 when the substrate 70 adheres to the printing plate 60 during the peeling step. In Figures 5 and 6, the printing plate 60 is fixed on the base 10. In the figures, 41 indicates the coloring area by the rubber roll 40, and 71 indicates the trace of the substrate 70 that adhered to the printing plate 60.

[0048] Figure 5 is a photograph of the printing plate 60 showing the state in which the substrate 70 has begun to partially adhere to the printing plate 60 (hereinafter also referred to as △). Figure 6 is a photograph of the printing plate 60 showing the state in which the area of ​​adhesion of the substrate 70 has increased (hereinafter also referred to as ×) (the state in which the substrate 70 is not attached to the printing plate 60 at all will be referred to as ○ below). In the peeling step, the condition of the printing plate 60 after peeling the substrate 70 from the printing plate 60 was observed and evaluated as either ○, △, or ×.

[0049] Figure 7 shows the evaluation results for ink A. In Figure 7, the horizontal axis represents the standing time, the vertical axis represents the printing pressure (M density), and ○, ×, and △ represent the adhesion evaluation results under those conditions. In the case of ink A, the substrate 70 began to adhere to the printing plate 60 after standing for 120 seconds (△), and the area of ​​adhesion of the substrate 70 to the printing plate 60 increased after 165 seconds or more. On the other hand, the presence or absence of adhesion of the substrate 70 to the printing plate 60 was hardly dependent on the printing pressure, and there was almost no difference in the range of M density from 0.12 to 0.68. Since the critical standing time at which adhesion begins to occur in ink A is short at 120 seconds, there is a high possibility that the substrate 170 will adhere to the plate cylinder 160 during color proofing at the start of printing on the printing press itself.

[0050] Figure 8 shows the evaluation results for ink B, and Figure 9 shows the evaluation results for ink C. With both ink B and ink C, no adhesion of the substrate 70 to the printing plate 60 occurred within the 300-second (5-minute) standing time normally required for color proofing at the start of printing on the printing press, in the range of printing pressure (M density) from 0.12 to 0.68. However, when the standing time was further extended, adhesion began to occur at a standing time of 480 seconds (8 minutes) (△), and the area of ​​adhesion on the substrate 70 increased at a standing time of 480 seconds (8 minutes) (×). Based on these evaluation results, the critical standing time for both ink B and ink C is considered to be 8 minutes. Therefore, if the color proofing at the start of printing can be completed in about 5 minutes, both ink B and ink C can be used as inks in the printing press without worrying about the substrate 170 sticking to the plate cylinder 160. Ink A has a tack value of 3.7, and ink B has a tack value of 3.6. Although their fluid viscosity is similar, the resins used in the inks are different.

[0051] (Correlation between the printing press itself and the ink adhesion evaluation device) Whether or not the substrate 170 adheres to the plate cylinder 160 in the printing press is basically determined by the performance of the ink, the printing pressure between the plate cylinder 160 and the substrate 170 when the ink is transferred to the plate cylinder, and the resting time during the printing pressure resting period. However, there are differences, such as the printing plate 60 of the ink adhesion evaluation device 100 being flat while the plate cylinder 160 of the printing press body is cylindrical. Therefore, in order to determine whether the substrate 170 adheres to the plate cylinder 160 of the printing press body at a predetermined printing pressure and resting time when using a certain ink, it is desirable to determine the correlation between the critical resting time in the printing press body and the critical resting time in the ink adhesion evaluation device 100 at a predetermined printing pressure.

[0052] Furthermore, since this correlation with critical settling time may differ depending on the ink or the value of the critical settling time, it is desirable to determine the correlation between the critical settling time in the printing press body and the critical settling time in the ink adhesion evaluation device 100 for several types of ink, and create a correlation graph. Furthermore, by determining how long it will take for the substrate 170 to adhere to the plate cylinder 160 in the printing press when using that ink, based on the correlation graph between the critical settling time measured using the ink adhesion evaluation device 100 and the critical settling time between the printing press body and the ink adhesion evaluation device 100, a more accurate prediction of ink adhesion in the printing press body can be made. However, in the evaluation results of inks A, B, and C evaluated using the ink adhesion evaluation device 100, the presence or absence of adhesion was determined by the standing time, and there was almost no effect from printing pressure. The difference between the ink adhesion evaluation device 100 and the printing press itself is mainly thought to be the difference in printing pressure, so if the effect of printing pressure is small in the evaluation results using the ink adhesion evaluation device 100, it is likely that the difference in adhesion evaluation results between the ink adhesion evaluation device 100 and the printing press itself will also be small.

[0053] In this embodiment, the printing plate 60 corresponds to the "printing plate," the substrate 70 corresponds to the "substrate," the base 10 corresponds to the "base," the rubber roll 40 and the metal roll 50 correspond to the "color spreading roll," the pressure adjustment mechanism 30 corresponds to the "pressure adjustment mechanism," the pressure measuring film 80 corresponds to the "pressure measuring film," the thickness adjustment film 75 corresponds to the "thickness adjustment film," the ink adhesion evaluation device 100 corresponds to the "ink adhesion evaluation device," and the pressure roll 20 corresponds to the "pressure roll."

[0054] While the above describes a preferred embodiment of the present invention, the invention is not limited thereto. It will be understood that various other embodiments can be made without departing from the spirit and scope of the invention. Furthermore, although the operation and effects of the configuration of the present invention are described in this embodiment, these operations and effects are examples and do not limit the invention. [Explanation of Symbols]

[0055] 10 bases 20 pressure rolls 30 Pressure adjustment mechanism 40 Rubber Rolls 50 metal rolls 60 print editions 70 Base material 75 Thickness adjustment film 80 Pressure Measuring Film 100 Ink adhesion evaluation device

Claims

1. An ink adhesion evaluation method for evaluating the adhesion of a substrate to a printing plate when ink is spread onto a printing plate using a color spreading machine and printed onto the substrate, The printing plate is fixed on the base of the color spreading machine, and the ink is spread on the printing plate with a color spreading roll in a color spreading step, A layering step in which the substrate is placed on top of the printing plate on which the ink has been spread, A printing pressure setting step is to apply a predetermined printing pressure to the substrate placed on the printing plate on the base using the color spreading roll and leave it to stand for a predetermined time, The process includes a peeling step of removing the color-spreading roll and peeling the substrate from the printing plate, An ink adhesion evaluation method that uses the resting time as a parameter to evaluate whether or not the substrate adheres to the printing plate in the peeling step, and to determine the critical resting time at which adhesion begins to occur.

2. The color spreading step includes the step of rotating the color spreading roll coated with the ink on the printing plate to spread the color, The printing pressure setting step includes adjusting the printing pressure using the pressure adjustment mechanism of the color spreading machine. The method for evaluating ink adhesion according to claim 1, wherein the measurement of the printing pressure is performed using a pressure measuring film.

3. Furthermore, the critical settling time was measured when printing using each ink in the printing press itself. The correlation between the critical settling time in the ink adhesion evaluation method using the aforementioned color spreading machine and the ink adhesion evaluation method using the printing press body was determined. The ink adhesion evaluation method according to claim 1, which determines the critical settling time in the ink adhesion evaluation method using the color spreading machine, which is necessary to prevent the substrate from sticking to the plate cylinder in the printing press body.

4. The device comprises a movable base, an ink spreading roll for spreading ink, a pressure roll for supporting the base from below, a pressure adjustment mechanism for adjusting the printing pressure of the ink spreading roll on the base, a printing plate detachably fixed on the base, and a pressure measuring film. The ink spreading roll spreads the ink onto the printing plate, and applies a predetermined printing pressure for a predetermined time from the substrate placed on top of the printing plate on which the ink has been spread. An ink adhesion evaluation device that peels off the substrate to which the predetermined pressure has been applied for the predetermined time from the printing plate and evaluates the adhesion of the substrate to the printing plate.

5. The pressure setting of the pressure adjustment mechanism is performed using the correlation between the set value of the pressure adjustment mechanism and the pressure measurement value obtained by the pressure measuring film. The pressure measurement value obtained by the pressure measuring film is measured by placing the pressure measuring film on top of the substrate which is superimposed on the printing plate and applying printing pressure with the pressure adjustment mechanism. The ink adhesion evaluation apparatus according to claim 4, wherein, when evaluating ink adhesion, a thickness adjustment film of the same thickness as the pressure measuring film is placed between the substrate and the color spreading roll, and printing pressure is applied.

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