JPS6410063B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a corrosion method in gravure plate making.

In conventional gravure, the printing plate is usually made of copper, and concave cells with different depths are formed therein depending on the gradation of the image to form a printing plate. However, a method for forming concave cells on a plate material is to transfer a carbon film on which a latent image has been formed in advance onto the surface of the plate material, develop it, and then apply a corrosive solution containing ferric chloride as the main component. , by corroding copper.

In other words, after development, the carbon film functions as a resist against corrosion, and has a film thickness that corresponds to the gradation, and the time it takes for the corrosive liquid to reach the surface of the plate material differs depending on the film thickness of the resist. come.

As a result, the total time for corroding the plate material is controlled, and concave cells with depths corresponding to the gradations are formed in the copper layer.

However, the time it takes for the corrosive solution to penetrate the resist depends not only on the resist film thickness, but also on the concentration of the corrosive solution,
Depends on moisture content, temperature and other factors. For this reason, the corrosion conditions are not uniformly determined, and in order to obtain a good printing plate, it is necessary to carry out corrosion and modify the corrosion conditions to match the properties of the resist at that time.

At present, for example, the following multi-liquid corrosion method is used as a corrosion method. That is, this is a method in which several types of corrosive liquids with different concentrations are prepared and corrosion is performed while changing the liquid from a high concentration liquid to a low concentration liquid.

Specifically, while actually corroding, the operator visually observes the progress of the corrosion on a gradation scale or pattern, grasping the properties of the resist, and selects corrosion conditions that match the properties during corrosion. do. That is,
When a corrosive solution whose main component is ferric chloride (FeCl ₃ ) penetrates the gelatin resist and reaches the copper surface of the printing plate, it reacts with the copper, and the copper (Cu) becomes cupric chloride (CuCl ₂ ).
Therefore, ferric chloride (FeCl ₃ ) becomes ferrous chloride (FeCl ₂ ).

Cu＋FeCl ₃ →CuCl＋FeCl ₂ CuCl＋FeCl ₃ →CuCl ₂ +FeCl ₂ Cu + 2FeCl ₃ → CuCl ₂ + 2FeCl _2Resist usually contains red pigments in addition to gelatin, and has the same color as the copper surface, but due to the corrosion reaction of copper, the color of the resist is black when viewed from the outside. By visually observing this change, it is possible to confirm that the corrosive liquid has penetrated. Then, by comparing the time from when the corrosive liquid is dropped onto the resist until corrosion starts, the properties of the resist can be ascertained.
In addition, corrosion is carried out while changing the corrosion conditions (such as liquid exchange) so as to obtain the set depth while grasping the progress of corrosion based on the permeation time of the corrosive liquid at each gradation scale.

However, since the above method replaces the corrosive solution while visually determining the progress of corrosion, the reproducibility varies between operators, making standardization difficult. Therefore, there is a drawback that a printing plate of stable quality cannot be obtained.

The present invention has been made in view of the above-mentioned problems.
The purpose of the present invention is to provide a corrosion method that allows the corrosion conditions such as sequence and usage time to be determined before corrosion, thereby obtaining a printing plate with no defects and stable quality.

Hereinafter, the present invention will be explained based on examples.

First, a method of testing the penetration characteristics of the resist of a gravure plate material using a test liquid that is a conductive solution will be described. Note that the test liquid is either non-corrosive or slightly corrosive.

FIG. 1 shows a cylindrical gravure plate material, and in the figure, reference numeral 10 denotes a resist that is brought into close contact with the surface of the copper layer of the plate material. An image to be printed is formed on the resist 10 by development, and a gradation scale for inspection (for example, () ()
() (4 stages) are also formed.

FIG. 2 shows an apparatus for inspecting the characteristics of the resist, and FIG. 3 shows how the apparatus is used. As shown in the figure, the resist electrode 12 is connected to the power supply + _Vcc via a resistor _R1 , and
The resist electrode 14 is grounded via a resistor _R2 . Further, the potential V _B of the resist electrode 14 is determined by the comparator 16 set to the threshold potential V _TH .
and the output CM (binary signal) of the comparator 16
is input to the AND circuit 18. AND circuit 1
A clock pulse CP of a predetermined frequency from a pulse oscillator 20 is input to AND circuit 1.
The output of No. 8 is counted by a counter 22, and the counted value is passed through a decoder 24 and displayed as penetration time data on a display section 26. Thus, the count value of the counter 22 is cleared by the clear button 28, and the resistance _R3 represents the resistance of the resist 10 as the object to be measured. The resist 10 is grounded by an electrode 30.

In the case of FIG. 3, the grounding point is the copper layer 32 of the plate material. Then, the inspection operation starts when the power is turned on, but in this case, the resist electrode 14 is connected to the resistor R ₂
Since the potential V _B is 0 [V] at time t ₀ to _{t 1} in FIG. 4A, it is lower than the threshold potential (+V _TH ). Therefore, the output of the comparator 16 is a binary signal of "0" (see FIG. 4B), and the clock pulse CP is blocked by the AND circuit 18, so the counter 22 does not count.

Here, the conductive test liquid SL is dropped onto the resist electrodes 12 and 14 on the resist 10 using a dropper. However, such test liquid
Since SL is conductive and comes into contact with the resist 10 and the resist electrodes 12 and 14, the current from the power supply (+V _cc ) flows through the resistor R ₁ from the time of dropping t _{1 .}
and flows into resistors _R2 and _R3 . Therefore,
The potential V _B becomes a divided voltage value (V _M ) of the combined resistance value of the resistor R ₁ and the resistors R ₂ and R ₃ (see FIG. 4A), and this is input to the comparator 16. Since this voltage division value V _M is larger than the threshold potential (+V _TH ),
The output CM of the comparator 16 becomes a binary signal "1" (see FIG. 4B). This causes the clock pulse to
CP is input to the counter 22 through the AND circuit 18, and a counting operation is started. This counter 2
The count value of 2 is converted into time data by the decoder 24, and the elapsed time from the counting start time _t1 is displayed on the display section 26.
is displayed.

When the test liquid SL is dropped onto the resist 10, the test liquid SL gradually permeates the resist 10, so that its resistance _R3 gradually decreases.
Therefore, the potential V _B at time t ₁ as shown in FIG.
After that, it gradually decreases and finally reaches the threshold potential.
V _TH becomes smaller (at time t ₂ ). As a result, the output CM of the comparator 16 becomes "0" again, the clock pulse CP from the pulse oscillator 20 is cut off by the AND circuit 18, and the counting operation of the counter 22 is stopped. In this way, the counter 22 counts from time t ₁ to t ₂ , that is, from the time when the test liquid SL is dropped onto the resist 10 until the test liquid SL penetrates to a predetermined depth (corresponding to the value of the threshold potential V _TH ). The clock pulses CP from the pulse oscillator 20 are counted and converted into time data by the decoder 24, which is then displayed on the display section 26 as the penetration time. Thereby, the penetration time of the test liquid SL into the resist 10 can be measured. Note that the counter 22
The count value is cleared by pressing the clear button 28.

The above measurements are performed on each of the four stages (,,,) of the gradation scale,
Each penetration time is examined.

Here, the set volumes of cells corresponding to each stage of the gradation scale have a corresponding relationship with the positive density of the original as shown in FIG. This relationship curve is appropriately selected and determined based on experience depending on the printed matter.

Further, the set volume of the cell has a correlation with the test liquid penetration time as shown in FIG.

Further, the permeation time of the test liquid and the permeation time of the corrosive liquid have a certain relationship for each type of corrosive liquid.

The penetration characteristics of the resist as shown in FIG. 6 are determined based on the measurement results by the inspection device, and this curve is used to determine the combinations of various corrosive liquids to be used.
The usage order and usage time allocation can be derived.

In addition, in order to corrode the plate material, the total corrosion time must also be determined, but this means that once the corrosive liquid reaches the plate surface, the amount of subsequent corrosion is determined by the concentration of the corrosive liquid (in the corrosion process). Based on the idea that the corrosion time is proportional to the total corrosion time, almost regardless of the concentration range (used), what is the minimum total corrosion time required to obtain the set volume of the cell at the highest shadow part ()? It is considered that the decision can be made based on the

Next, in comparison with the above-mentioned resist characteristic graph (FIG. 6), a method for obtaining reference data for clearly deriving combinations of corrosive liquids and the total corrosion time will be described.

First, a test as shown in FIG. 7 is performed on a predetermined test resist for each of a plurality of types (A, B, C, D, and E) of corrosive liquids used with different concentrations.
That is, this test resist is closely adhered to the copper layer, and a desired gradation scale is formed from the highlight area to the shadow area, for example ().
It is divided into a large number of sections as shown in () ()..., and a plurality of sections for test liquid and corrosive liquid are provided for each gradation.

And for example all tones ()()()
The test liquid is dropped into a predetermined section of the resist for ...... and its penetration time (t ₁ ) (t ₂ )...
(t ₁ )......(t ₆ )..., then apply corrosive solution to other sections to perform corrosion, then remove the resist and remove the cells formed in the copper layer below. Volume of each section (V ₁ ) (V ₂ )...
…V ₁ ……… is measured. Such measurements are carried out for each corrosive liquid A, B, C, etc.

Figure 8 is a graph of this measurement result.
This is for corrosive liquid A (for example, 40°Be).
This graph shows the relationship between test liquid penetration time (t) and cell volume (V) for various corrosion times (T).

As will be described later, the total corrosion time of the plate material will be determined based on this data.

Furthermore, a graph as shown in FIG. 9 is also created based on the above measurement results. This graph shows, for example, the corrosion time (T ₅ ) of various corrosive liquids (A, B, C...
. . .) shows the relationship between the test liquid penetration time (t) and the cell volume (V). Such graphs are also drawn for other corrosion times (T ₁ ), (T ₂ ), etc. (not shown).

Furthermore, the relationship between the permeation time of the test liquid and the permeation time of the corrosive liquid is graphed as shown in FIG. 10 for each corrosive liquid (A, B, C, . . . ). The horizontal axis of this graph is scaled with the penetration time (t) of the test liquid in each gradation part of the resist, and the vertical axis is scaled with the penetration time of the corrosive liquid in each of the same gradation parts. In this case, the permeation time of the corrosive liquid corresponding to the permeation time of the predetermined test liquid is the time from immediately after the corrosive liquid is dropped until the corrosive liquid reacts with the copper and turns black as described above.

Note that since the corrosive liquid usually has conductivity, the permeation time of the corrosive liquid may also be measured by the measuring device, and this may be plotted on the vertical axis.

By determining the correlation between the penetration characteristics of the test liquid and the volume of the cell portion as described above, the measurement results of the penetration characteristics of the resist 10 of the plate material using the test liquid are adjusted as described above based on this correlation. Therefore, it is possible to determine the corrosion conditions caused by the corrosive liquid.

As mentioned above, resist properties change depending on the time due to changes in temperature, humidity, etc., but when corrosion is about to start, the permeation properties are tested using a measuring device using a test liquid, and Suppose we get the result shown in the figure. This graph is based on the cell volume of each gradation part ()()()() in Figure 1, since it has been determined in advance from experience. It depicts the relationship between the test liquid penetration time and the cell volume.

Next, we overlapped Fig. 6 and Fig. 8 and compared them by focusing on the most shadow part of each.
If the curve closest to that of FIG. 8 is selected, for example the curve (T ₅ ), it is determined that the most appropriate total corrosion time for the resist is T ₅ .

Although the graph in FIG. 8 is for the corrosive liquid used initially in the corrosion process, graphs for other corrosive liquids may be used.

Once the total corrosion time (for example, T ₅ ) has been determined in this manner, the graph in FIG. 9 corresponding to that time is selected and compared by overlapping them as shown in FIG. 11.

For the resist 10, the curve 32 in FIG.
It is most desirable to set conditions so that corrosion occurs along the Therefore, a curve whose slope is closest to the slope of curve 32 in FIG. 6 is selected from FIG. 9.
In this case, with points 34 and 36 as boundaries, the left part is closest to curve B, the center part is closest to curve C, and the right part is closest to curve D.

Corrosive liquid D is applied to the resist portion having the characteristics of the test liquid penetration time from t _D to t _C , corrosive liquid C is applied to the resist portion whose penetration time is t _C to t _B , and corrosive liquid is applied to the resist portion whose penetration time is below t _B. By applying the influence of B, corrosion along the curve 32 in FIG. 6 becomes possible. Therefore, B, C, and D are selected as the corrosive liquids to be used.

Further, the order in which the corrosive liquids are used is set as B, C, and D as shown in FIG. Use order B, C,
By setting D, B with a high concentration reaches the shadow part quickly and starts corroding the copper layer first, then C with a medium concentration reaches the middle part, and then C with a low concentration reaches the highlight part. D arrives.
Therefore, the shadow part is mainly corroded by B, C, and D, the middle part is mainly corroded by C and D, and the highlight part is mainly corroded by D.

That is, the corrosive liquid B has already completely penetrated into the resist portion where the test liquid penetration time is shorter than the point 34 and has reached the plate surface. And point 34 and point 3
In the resist portion corresponding to the penetration time between 6 and 6, the corrosive liquid B does not completely penetrate, and reaches the plate surface only after the next corrosive liquid C permeates after the liquid exchange. The resist portions whose penetration time is longer than point 36 are affected by the next corrosive liquid D after the liquid exchange.

Next, the use time distribution of the selected corrosive liquids B, C, and D is determined based on the above points 34 and 36.

That is, the initial usage time of corrosive liquid B is at point 34.
The resist portion corresponding to the penetration time _tB of the test liquid in is defined as the time required for the corrosive liquid to completely penetrate.

The next usage time of the corrosive liquid C is the time required for the corrosive liquid to completely penetrate the resist portion indicated by the penetration time t _C of the test liquid at point 36.

The usage time of the final etchant D is the time required for the etchant to completely penetrate the resist portion corresponding to point 38, that is, the lightest resist portion, and the time required to erode the cell volume of this lightest portion. Add the time.

Therefore, the first usage time of corrosive liquid B is
From the graph in Figure 0, it is determined as the permeation time x ₁ of the corrosive liquid _{B, which corresponds to the permeation time t B} of the test liquid. The next usage time of the corrosive liquid C is expressed as the time required for the corrosive liquid C to completely penetrate the resist portion corresponding to the test liquid penetration time _tC . However, the first
As shown in Figure 2, it is considered that the corrosive liquid B has already penetrated to some extent into the resist portion corresponding to the test liquid penetration time _tC . Therefore, the time required for the corrosive liquid _C to completely penetrate the resist portion corresponding to the test liquid penetration time t c is slightly longer than the time x ₂ required for only the corrosive liquid C to completely penetrate the resist portion corresponding to the penetration time t _c . considered to be short. As for this subtraction time, the corrosive liquid B has already penetrated into the resist part corresponding to the test liquid permeation time t _B (Fig. 12 A) in the resist corresponding to the test liquid permeation time t _c , and corrosion is caused. Since the time required for the liquid C to diffuse and permeate that part is considered to be minute, it is appropriate to set the resist part at t _B to the time x' ₂ for the corrosive liquid C to permeate.

That is, the time (x ₂ -x' ₂ ) is the usage time of the corrosive liquid C.

Further, the next use time of the corrosive liquid D is determined by paying attention to the permeation of the corrosive liquid into the resist portion in the lightest part () and the corrosion of the plate material. The volume of the cell in the lightest part () is predetermined, and the corrosion time after the corrosive liquid penetrates into the resist in that part to obtain the set cell volume is also determined and determined in advance.

Therefore, the usage time of the etchant D is the sum of the time required for the etchant D to completely penetrate the lightest resist area, and the subsequent corrosion time required to obtain the cell set volume in the lightest area. It's time. However, the permeation time of the corrosive liquid D required to completely permeate the lightest resist portion is as follows:
In the resist part corresponding to the test liquid penetration time _tD , corrosive liquids B and C have already penetrated before corrosive liquid D penetrates.
Since it is thought that the corrosive liquid has penetrated to some extent (parts A and B in Figure 12), use the same method to determine the usage time of the corrosive liquid C described above to the resist area at the test liquid permeation time _tD . Penetration time of corrosive liquid D
The value obtained by subtracting the penetration time x _{′ 3} of the corrosive liquid D into the resist portion during the test solution penetration time t _c from x ₃ (x ₃ −x′ ₃ )
It is assumed that is the penetration time of the corrosive liquid D in the lightest part of the resist. Furthermore, if the corrosion time required to obtain the predetermined cell volume at the lightest portion is m, then the usage time of the corrosive liquid D will be (x ₃ −x' _3+n ).

Here, the total usage time of corrosive liquids B, C, and D almost matches the aforementioned total corrosion time T.
There is a relationship: x ₁ +(x ₂ −x′ ₂ )+(x ₃ −x′ _3+n )=T.

In other words, if n types of corrosive liquid are used,
x ₁ +(x ₂ −x′ ₂ )+(x ₃ −x′ ₃ )+……+(x _o-1 −x′ _o
-1 )
The time allocation for each corrosive liquid may be determined using the relationship +(x _o −x′ _o+n )=T.

When setting the above corrosion conditions, the conditions can be set by storing previously determined reference data as shown in Fig. 7 in the computer, and having the computer perform arithmetic processing such as comparing this data with the data shown in Fig. 6. It can also be set.

In this way, once the type of etchant to be used and the respective duration of use are determined, etchants B, C, and D are sequentially applied x ₁ from above the resist 10 while rotating the gravure plate material at a constant speed using an etcher (not shown). , x ₂ −x′ ₂ , x ₃ −x′ _3+n
By supplying it for a period of time, cells of a set volume can be formed in the copper layer of the plate material.

In addition, if it is found that the resist characteristics are undesirable by the test using the test liquid,
If the test liquid is not corrosive, you only need to re-create the resist, or if the test liquid is slightly corrosive, simply sand the plate material lightly with sandpaper, etc. Just form it again. Usually, the corrosive liquid has conductivity, and when the above-mentioned inspection is performed using the corrosive liquid, it is necessary to recreate the plate material itself.

Since the present invention has the above-described configuration and operation, it has the following effects.

Since corrosion conditions are set before corrosion and corrosion occurs under those conditions, cell volumes with excellent reproducibility can be obtained according to the desired image gradation on the plate material, and quality can be stabilized without requiring any skill. It is possible to produce printed plates.

Since it is possible to produce printing plates with stable quality, the burden of plate correction in post-processing is greatly reduced.

It is also possible to determine the setting of the corrosion conditions from a graph, and it is also possible to determine the setting by computer processing by storing the test results as shown in FIG. 7 in advance in a computer. Moreover, it is possible to control the corrosive machine and corrode the plate material under conditions determined through arithmetic processing.

Example 4 gradation scales (positive density: 1.7, 1.7,
1.2, 0.8, 0.4), the penetration time of the conductive test liquid was measured, and the results were 2.6 [sec] and 9.4
[sec], 30.7 [sec], and 72.5 [sec]. Also,
The cell setting volume according to this gradation scale is fixed: 0.8×10 ⁶ [μm ³ ], 0.4×10 ⁶ [μm ³ ], 0.1×
10 ⁶ [μm ³ ], 0.05×10 ⁶ [μm ³ ]. Therefore, a graph of the measured "test liquid penetration time" versus "cell setting volume" is created. Next, we focused on the cell volume at the darkest part, 0.8×10 ⁶ [μm ³ ], and calculated the total corrosion time by calculating the graph of "test liquid penetration time" versus "cell volume" when the corrosion time was changed. is determined to be 15 minutes. And "test solution penetration time" vs. "cell volume" when corroded for 15 minutes with each concentration of corrosive solution.
The graph and the measured “test liquid penetration time”
By comparing the graph with the graph of "cell setting volume", it is decided to use three corrosive liquids, 40°Be, 39°Be, and 38°Be, in this order. Next, “Test liquid penetration time”
Compare the graph of cell volume versus cell volume and the previously created graph of test liquid penetration time versus cell setting volume to find changes that indirectly indicate liquid exchange, and find the test liquid that corresponds to each change. Penetration time, 4 [sec], 24
Find [sec]. From the graph of “testing liquid penetration time” vs. “corrosion liquid penetration time”, the usage time of 40°Be liquid is 40°Be, which corresponds to the penetration time of testing liquid 4 [sec].
The penetration time of the liquid is 240 [sec], which is determined to be 4 minutes, and the usage time of the 39°Be solution is the penetration time of the test solution, which is 24 minutes.
It is 290 [sec], which is obtained by subtracting the penetration time of 39°Be liquid, 120 [sec], which corresponds to the penetration time of the test liquid, 4 [sec], from the penetration time of 410 [sec], which corresponds to the penetration time of 39°Be liquid, which corresponds to [sec]. , it is determined to be 4 minutes and 50 seconds. In addition, the usage time of the 38°Be solution is the penetration time of the test solution in the lightest part.
Penetration time of 38°Be liquid equivalent to 72.5 [sec]430
[sec] corresponds to the penetration time of the test liquid 24 [sec]
The time required to corrode the predetermined cell volume of 0.05×10 ⁶ [μm ³ ] in the lightest part is 2 minutes and 30 seconds, which is 220 seconds after subtracting the penetration time of the 38°Be solution, which is 210 [sec]. The added time is determined to be 6 minutes and 10 seconds.

Therefore, the corrosion conditions to obtain a standard cell volume from this resist state are: 40°Be solution for 4 minutes, then 39°Be solution for 4 minutes 50 seconds, and finally 38°Be solution for 6 minutes 10 seconds. It was decided that the corrosion would be carried out for a total of 15 minutes, which is equal to the total corrosion time of 15 minutes that was originally calculated, and the corrosion occurred according to these conditions. As a result, the cell volume of each scale almost matched the initially set cell volume.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a cylindrical gravure plate material. FIG. 2 is a circuit diagram showing an example of a measurement circuit of the resist inspection device, FIG. 3 is an explanatory diagram showing the relationship between the resist inspection device and the plate material, and FIG. 4 is a partial waveform diagram in the measurement circuit. Figure 5 is a graph of positive concentration vs. cell set volume, Figure 6 is a graph of test liquid penetration time vs. cell set volume, Figure 7 is an illustration of the test resist, and Figure 8 is corrosion time. Figure 9 is a graph of test liquid penetration time versus cell volume when the type of corrosive liquid is changed. Figure 10 is a graph of test liquid permeation time versus cell volume when the type of corrosive liquid is changed. FIG. 11 is a graph of test liquid penetration time versus cell volume, which compares the graphs of FIGS. 6 and 9. FIG. 12 is a schematic diagram showing a vertical cross section of the resist.

Claims (1)

[Claims] 1. Form a large number of gradation areas in the resist of a predetermined gravure plate material, determine the penetration time of the test liquid in each gradation area, calculate the cell volume formed by the corrosive liquid in each gradation area, and calculate the total corrosion time and corrosion. The results are calculated for each case in which the type of liquid is changed, and the first relationship showing the relationship between the test liquid penetration time and cell volume using the various total corrosion times as parameters for each of the above corrosive liquids, and the above various total corrosion times are determined. Regarding the corrosion time, a second relationship showing the relationship between the test liquid penetration time and the cell volume using each of the above corrosive liquids as a parameter is determined, and a third relationship showing the relationship between the test liquid penetration time and the penetration time of each of the above corrosive liquids is determined. The relationship is determined in advance, and the penetration time of the test solution is measured into the resist of the gravure plate material to be subjected to corrosion. Find the four relationships, compare the first relationship with the fourth relationship, select the parameter with the highest correlation from the first relationship, determine the total corrosion time, and then determine the total corrosion time. determining the type and order of use of the corrosive liquid to be used by comparing the second relationship and the fourth relationship regarding the total corrosion time and selecting the parameter with the highest correlation from the second relationship;
Further, determine the test liquid penetration time when this selected parameter changes, determine the usage time of each corrosive liquid selected from the third relationship above based on the determined test liquid penetration time, and A multi-liquid corrosion method in gravure plate making, characterized in that the gravure plate material is then corroded based on the above determination.