JPH10250249A - Original plate for pad printing and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To strengthen the durability of a doctor ring, and enhance the stability of printing quality by specifying the depth of an ink reservoir part, and specifying the dispersion thereof only in the case of using transparent ink. SOLUTION: An ink reservoir part 2 is cut-formed in an original plate 1. The surface of ferro-metal or nonferro-metal as the material of the original plate 1 is intensified in hardness as well as toughness by a surface hardening treatment so that the durability of a doctor ring is improved. The surface hardness is made HRC 60 or more. An average depth of the ink reservoir part is 20-60μm in the case of transparent ink, and it is 2-80μm in the case of opaque ink from the view point of finish appearance and pattern accuracy. In addition, in order to restrain printing unevenness or inner surface dispersion, the dispersion is limited within 5% with respect to a predetermined depth only in the event of using transparent ink. A bottom surface roughness of the ink reservoir part 2 is set within a half of the average depth and made not lower than 1μm so as to render an ink retaining quantity of the pad stable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an original for pad printing (hereinafter simply referred to as "original") and a method for producing the same. More specifically, the present invention relates to an original plate used for reciprocating pad printing or rotary pad printing, and a method of manufacturing the same.

[0002]

2. Description of the Related Art A conventional original plate is manufactured using a single plate material such as steel, copper, brass or glass, or a plate material such as a synthetic resin, and an ink reservoir is formed on the surface of the material. Has been established.

The ink reservoir is formed by etching with a chemical corrosive liquid such as a ferric chloride solution when the plate material is steel, copper, brass or glass. A photosensitive resin layer is applied on a film, and after exposure, an uncured photosensitive resin layer that has not been exposed to light or an alcohol solution is washed and formed.

[0004] A plate made of steel is made of SKD11 or the like quenched to a hardness of HRC 60 or more, has a high durability against doctor ring, and is the most widely used plate. On the other hand, plates made of copper, brass, and glass
It has the disadvantage that its surface is soft or brittle.
Therefore, many of them are not used because they are easily damaged and have low doctoring durability. The photosensitive resin plate has a durability that is incomparably lower than that of the steel plate, but is used for printing prototypes and small-lot products because of its advantages of low cost and easy plate making.

[0005] Etching apparatuses using a chemical etchant are classified into dip type, paddle type, spray type and the like, if classified according to the method of applying the etchant. In addition, there are a batch type and a conveyor type if classified according to the method of installing the plate material. In order to obtain an ink reservoir having a constant depth without inclination of the bottom surface, etching conditions must be strictly controlled in any apparatus. For the plate, set the depth of the ink reservoir to 2
It is often used by forming to about 0 to 30 μm,
At this time, a variation of a depth of about ± 5 μm from the average value usually occurs. In addition, the surface of the steel material, which is the main stencil for mass production, is usually wrapped, but polishing scratches and tissue nests may remain on the surface as defects, and a sufficient inspection is required before etching. It has been. As described above, the depth of the etched ink reservoir is also likely to vary, and inspection is indispensable even after etching. Since the depth varies as described above, it is difficult to obtain a uniform printed surface.

[0006]

If the depth of the formed ink reservoir is uniform and the roughness of the bottom surface is constant, the ink is uniformly transferred to the printing material over the entire surface, resulting in color unevenness and chipping. The number of defects due to the However, in the method of manufacturing an original plate by etching, it is difficult to obtain an ink reservoir with a certain depth, and furthermore, there is variation in the crystal structure of the plate material, or the conditions for applying a chemical etchant to the plate surface are not uniform. As shown in FIG. 5, the bottom surface of the ink reservoir 50 tends to be uneven.

[0007] In the case of a resin plate, the surface is easily scraped off by doctoring, resulting in poor durability, and is difficult to manage because it is affected by moisture. Further, there is a problem that solid printing cannot be performed because the surface is soft and the doctor pressure cannot be supported.

In view of the circumstances described above, the present invention has a uniform depth of the ink reservoir formed, a uniform bottom surface with no inclination, and a hard surface with high durability. ,
An object of the present invention is to provide an original plate capable of forming a printing surface having a large area and a uniform film thickness, and a method for manufacturing the same.

[0009]

In the original plate of the present invention, the average depth of the ink reservoir is 2 μm or more and 80 μm or less, and the variation is within 5% of the predetermined depth only when a transparent ink is used. It is characterized by having.

Further, in the original plate of the present invention, the roughness of the bottom surface of the ink reservoir is within 1/2 of the average depth and 1 μm
It is preferable not to fall below.

The original plate of the present invention is preferably made of a ferrous metal or a non-ferrous metal having a surface exhibiting a certain hardness of HRC 60 or more by a surface hardening treatment.

Further, the method of manufacturing an original plate according to the present invention is characterized in that the ink reservoir is formed by electric discharge machining.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an original plate of the present invention and a method for producing the same will be described with reference to the accompanying drawings.

FIG. 1 is a sectional view showing an embodiment of the original plate of the present invention.

As shown in FIG. 1, an ink reservoir 2 is engraved on the original 1. The material of the original plate 1 includes ordinary steel, stainless steel, alloy steel, rimmed steel, killed steel,
Ferrous metals such as capped steel and semi-killed steel, or non-ferrous metals such as ordinary copper, brass, zinc and aluminum can be used. The surface hardness of these ferrous metals or non-ferrous metals is preferably increased by a surface hardening treatment. When the surface hardness increases, the toughness also increases, so that the doctoring durability increases. The surface hardness is HRC 60 or more, preferably HRC 60 to 70, according to the examples described later. Further, the surface hardening treatment,
Although it is appropriately selected depending on the material and the set value of the hardness, for example, quenching, surface nitriding, ion implantation, or the like can be used alone or a plurality of them can be used.

As a method of processing the ink reservoir 2, it is preferable to use electric discharge machining which can set processing conditions quantitatively. By such electric discharge machining, the depth of the ink reservoir 2 can be made uniform and the roughness of the bottom surface can be made constant. For this reason, a printing surface having a large area and a uniform film thickness can be obtained. In addition, since the production variation is unlikely to occur in the depth of the ink reservoir and the roughness of the bottom surface, it is possible to secure the stability of original production, which was difficult with the original produced by conventional etching.

The average depth of the ink reservoir is from 20 μm to 60 μm in the case of transparent ink according to the embodiment described later.
In the case of an opaque ink, it is preferably 2 μm or more and 80 μm or less in terms of finished appearance and pattern accuracy.
m or less is preferable. Further, in order to suppress printing unevenness and in-plane variation, the variation is 5% of a predetermined depth.
It is preferable to set it within.

Further, the roughness of the bottom surface of the ink reservoir is:
In order to stabilize the ink holding amount of the pad, the average depth of 1
/ 2 and not less than 1 μm.

Next, the original plate of the present invention will be described based on examples, but the present invention is not limited to only these examples.

Examples 1 to 6 and Comparative Examples 1 to 12 Twelve original plates made of SUS430 were prepared. With respect to the six masters, ink reservoirs having a size of 13 mm × 13 mm and six different depths were formed by electric discharge machining (Examples 1 to 6). The remaining six masters were etched to a size of 13 mm x 13 mm.
To form ink reservoirs of six different depths (Comparative Examples 1 to 5)
6).

In the electric discharge machining, copper is used for the electrode, and the machining speed is 0.0097 g / min and 0.0020 g.
/ Min under two conditions.

The etching was performed using a ferric chloride solution as a chemical etchant for an etching time of 1 to 3 days.

Next, the depths of the ink reservoirs engraved on the 12 original plates were measured with a surface roughness meter. Table 1-2
2 shows a variation between the target value and the measured value of the depth of the ink reservoir formed by the electric discharge machining and the etching (variation from the target value of the measured value).

[0024]

[Table 1]

[0025]

[Table 2]

As a result, it was found that an ink pool having a uniform depth can be formed by using the electric discharge machining method.

Next, the average depth of the ink reservoirs of Examples 1 to 6 subjected to the electric discharge machining and the light transmittance of the printing surface when printing was performed using a transparent ink were examined. Table 3 shows the results.

The light transmittance was measured using incandescent bulbs, fluorescent lamps, C
The attenuation of light emitted from RT and the like was measured.

[0029]

[Table 3]

When the depth of the ink reservoir is deep, the pattern accuracy is poor due to the protrusion of the ink. On the other hand, when the depth is shallow, the variation in the ink density within the printing surface becomes large, and the uniform and appropriate film thickness is obtained. I could not get it. The average depth of the ink reservoir can be up to 20 to 60 μm because the required transmittance is 60% or more, but 40 μm is the best in terms of reduced in-plane variation and improved repetition accuracy. .

Examples 7 to 15 Further, the appearance and pattern accuracy when using an opaque ink were examined for an original plate having an average depth of the ink reservoir of 1 μm to 150 μm.

According to Table 4, when the ink reservoir is 1 μm,
It becomes transparent due to the variation of the film thickness. Also, 100
In the case of more than μm, the pattern collapsed, and all were impractical.

As a result, it was found that the average depth of the ink reservoir is preferably 2 μm or more and 80 μm or less in the case of opaque ink.

[0034]

[Table 4]

Examples 16 to 21 Next, the roughness of the bottom surfaces of the ink reservoirs of the six masters subjected to electrical discharge machining to an average depth of the ink reservoirs of 40 μm, and transparent inks were printed using these masters. In this case, the color variation (color difference) ΔE in the printing surface was examined. Table 5 shows the color difference ΔE with respect to the roughness of the bottom surface. For example, FIGS.
And among the masters subjected to the electric discharge machining, the master 1 having a bottom surface roughness of 2 μm, 12 μm and 20 μm of the ink reservoir.
1, 21 and 31 are shown.

The color difference is measured by a color difference formula based on the Hunter color system from the colorimetric values of the spectrophotometer.

[0037]

[Table 5]

As a result, the color varies within the printing surface due to the roughness of the bottom surface of the ink reservoir, but the roughness of the bottom surface of the ink reservoir is determined by the color difference (ΔE) at which no practical problem occurs.
Is less than 3, it is possible to 2 ~ 20μm,
12 μm is the best in terms of obtaining more sharpness. In addition, the roughness of the bottom surface is to adjust the amount of ink brought out by the pad, so that it is set to within 1/2 of the average depth, and the thickness of each part of the brought out ink varies, so that 1 μm is used. Preferably it does not fall below.

Examples 22 to 25 Next, a master 1 made of a cold rolled steel plate (SPCC) was used.
And three original plates made of stainless steel (SUS). Then, quenching treatment such as carburizing or high frequency was used as a surface hardening treatment for each master. The surface hardness was measured by measuring the Rockwell hardness, and the doctoring durability was evaluated by the number of times of printing until a scratch was formed on the original plate surface when a steel blade was used. Table 6 shows the relationship between the surface hardness of the master and the doctoring durability.

[0040]

[Table 6]

As a result, it was found that when the surface hardness was HRC 60 or more, the durability was dramatically improved.

[0042]

As described above, according to the present invention,
By using electric discharge machining with high machining accuracy, it has an ink reservoir with a uniform depth and a uniform roughness on the bottom surface, and it is possible to form a printing surface with a large area and a uniform film thickness. Can produce a large original.

Further, by manufacturing an original using electric discharge machining with high machining accuracy, a large number of originals having the same shape can be manufactured without variations in the depth of the ink reservoir and the roughness of the bottom surface. Therefore, printing quality stability can be improved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of an original according to the present invention.

FIG. 2 is a cross-sectional view showing an original plate in which a depth of an ink reservoir is 40 μm and a bottom surface has a roughness of 2 μm.

FIG. 3 is a cross-sectional view showing an original plate in which a depth of an ink reservoir is 40 μm and a bottom surface has a roughness of 12 μm.

FIG. 4 is a cross-sectional view showing an original plate in which a depth of an ink reservoir is 40 μm and a bottom surface has a roughness of 20 μm.

FIG. 5 is a sectional view showing a conventional original plate.

[Explanation of symbols]

 1 original plate, 2 ink reservoirs.

Claims (4)

[Claims] An average depth of an ink reservoir is 2 μm or more and 8 μm or more.
An original plate for pad printing having a thickness of not more than 0 μm and a variation within 5% of a predetermined depth only when a transparent ink is used. 2. The pad printing original plate according to claim 1, wherein the roughness of the bottom surface of the ink reservoir is within 1/2 of the average depth and not less than 1 μm. 3. The pad printing plate precursor according to claim 1, wherein the material is a ferrous metal or a non-ferrous metal having a surface showing a certain hardness of HRC 60 or more by a surface hardening treatment. 4. A method for producing an original plate for pad printing, wherein an ink reservoir is formed by electric discharge machining.