JP2010240897A - Doctor for gravure coating - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a doctor for gravure coating which does not bring about any defects such as coating stripe which occur due to the contact friction between a rotary gravure printing plate and a fixed doctor, with regard to gravure coating for performing continuous rolling process to a long support which is consecutively conveyed. <P>SOLUTION: This doctor for gravure printing 3 has a mounting part 20, a blade part 22 which projects from the mounting part 20 like a thin sheet and has a smaller thickness T2 than the thickness T1 of the mounting part 20. The mounting part 20 is a spot where it is fitted into a doctor holder 4. The length L1 of the blade part 22 which extends in a direction where the blade part 22 projects from the mounting part 22, is 1.5-3.0 mm. Besides, the Vickers hardness of the surface of the blade part 22 is 920-1,500 Hv. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a doctor used in gravure coating mainly in a field requiring precise required quality such as an optical member or an electronics field. More specifically, the present invention relates to a doctor that does not cause various application defects caused by scraping of the doctor in gravure coating for continuously processing a long support that is continuously conveyed.

  Gravure coating has long been used in the application of packaging materials, industrial materials, electronic substrate materials, etc., as one method of applying a coating solution to a desired film thickness on a continuous support that is continuously conveyed. I came. The gravure coating can be applied with high accuracy even if it is a thin film, and has a feature that the viscosity range that can be applied is wide.

  In general, as shown in FIG. 1, a gravure coating apparatus has a plate cylinder 1 in which a plate surface (gravure plate) is engraved in a cell shape or a spiral shape on a cylindrical surface, an ink pan 2 in which a coating solution is stored, and an extra coating. Coating liquid is supplied to a plate-like doctor 3 that scrapes off the liquid, a doctor holder 4 that fixes the doctor 3, a back roll 6 that presses a support (printed material such as paper) 5 to the plate cylinder 1, and an ink pan (not shown). A uniform coating film 7 can be formed on the support 5. The coating liquid stored in the ink pan 2 is scraped up by the plate surface as the plate cylinder 1 rotates, and the coating liquid scraped up by the plate surface is weighed to an appropriate amount by the doctor 3 and continuously from an unshown unwinding device. A uniform coating film 7 is formed by being uniformly transferred onto the long flexible support 5 supplied to the substrate.

  The gravure coating apparatus includes a forward rotation system in which the plate cylinder rotates in the same direction as the long support as shown in FIG. 1, and a plate cylinder in the direction opposite to the long support. There are a rotating reverse method, a floating method without a back roll behind a long support, and a floating reverse method combining them as shown in FIG. In the floating reverse method or the like, guide rolls 8 are disposed on both sides of the plate cylinder 1, and the support 5 is pressed against the plate cylinder 1 by the guide rolls 8.

  In the gravure coating device, the coating liquid scraped up from the ink pan by the plate cylinder is scraped off into the ink pan by the doctor blade edge except for the coating liquid in the plate surface, and the coating liquid remaining in the cell is uniformly coated. The Therefore, the doctor's scraping accuracy of the coating solution has a large effect on the coating surface directly, so that the doctor's blade surface is evenly cut to make it uniform over the entire width of the doctor so that non-uniform defects do not occur. It is necessary to.

  However, the rotating plate cylinder and the blade edge of the doctor fixed by the doctor holder are always in a frictional state, so uneven wear occurs on the blade edge of the doctor during continuous coating and the appropriate amount of coating liquid is scraped off. However, it often causes coating streaks, resulting in a serious problem resulting in a decrease in yield in continuous production. In addition, when such a problem occurs, the doctor must be replaced with a new one, and in that case, loss of replacement work time or time loss due to doctor habituation operation has a significant effect on the operating rate. give. Furthermore, since the scraping accuracy of the coating liquid directly affects the coating surface directly, the doctor is made by an expensive manufacturing apparatus using a limited material, which is a burden in terms of production cost.

  In order to improve the application stripe, it is important that the doctor blade edge is uniform, does not wear, and that the wear width when worn is uniform and uniform.

  On the other hand, a doctor (for example, refer to Patent Document 1) with improved wear resistance is known.

  This doctor has a plate-shaped base made of a material having elasticity, and a wear-resistant layer made of a material harder than the base coated on the surface of the base, and the spring constant of the doctor is The Vickers hardness of the wear-resistant layer is 1000 to 3800 Hv. Further, surface irregularities are suppressed by applying a CVD method and a PVD method to the formation of the wear-resistant layer of the doctor.

  However, even a doctor with an abrasion resistant layer on an elastic base is held by a doctor holder in a gravure coating device, and the doctor's holding part is long. If the length to be shortened becomes short, the elastic force becomes insufficient, and the degree of freedom of the doctor becomes small.

  If the doctor is not sufficiently bent, the contact state will be biased in contact with the plate surface, resulting in uneven wear.

  In addition, since the doctor is used in contact with the plate surface, the hardness of the doctor is usually weaker than that of the gravure plate for the purpose of protecting the gravure plate.

  Therefore, even if it has an abrasion-resistant layer like the above-mentioned doctor, abrasion cannot be suppressed completely, and abrasion occurs during continuous coating. If this wear width is uniform, even if it is worn, no problem will occur on the coated surface. However, if the wear width varies, problems such as coating streaks will occur. In fields that require precise required quality, such as optical components and electronics, even if the coating surface is good immediately after coating, the problem of coating streaks during continuous coating cannot be completely solved. .

JP-A-8-197711

  The present invention is a gravure coating that can solve the uneven wear of the doctor blade edge, the life of the doctor, etc., caused by contact friction between the plate surface of the rotating plate cylinder and the fixed doctor as described above. Is to provide a doctor.

As a result of intensive efforts to solve the above problems, the present invention has been completed.
The invention according to claim 1 is a doctor for gravure printing having a mounted portion and a blade portion protruding in a thin plate shape with a thickness smaller than the thickness of the mounted portion from the mounted portion. The length in the direction in which the blade portion protrudes from the attached portion is 1.5 mm or more and 3.0 mm or less, and the Vickers hardness of the surface of the blade portion is 920 Hv or more and 1500 Hv or less. It is characterized by.
In the invention according to claim 2, the attached portion and the blade portion have a common base material, and the blade portion further has a surface layer covering the surface of the base material, The thickness is 0.05 mm or more and 0.20 mm or less.
The invention according to claim 3 is characterized in that the surface layer is composed of an inorganic particle-dispersed composite plating layer containing ceramic particles.
According to a fourth aspect of the present invention, the surface layer is an organic containing inorganic particle-dispersed composite plating layer containing ceramic particles covering the surface of the base material, and fluorine-based resin particles covering the inorganic particle-dispersed composite plating layer. The doctor according to claim 1 or 2, wherein the doctor is composed of a resin-dispersed composite plating layer.
The invention according to claim 5 is the doctor according to any one of claims 1 to 4, wherein the base material is any one of soft steel, stainless steel, and plastic having elasticity and toughness.
An invention according to claim 6 is a gravure coating apparatus comprising a plate cylinder in which a plate surface is formed on the surface of a cylinder, and a doctor according to any one of claims 1 to 5 that scrapes off an excessive coating liquid on the plate surface. It is a coating device.
The invention according to claim 7 is a manufacturing method of a coated product for forming a coating film on at least one surface of a support, and the coating liquid is applied onto the support that is continuously conveyed using the coating apparatus according to claim 6. It is the manufacturing method of the coating material characterized by apply | coating and forming the coating film on the support body.
The invention according to claim 8 is the method for producing a coated product according to claim 7, wherein the coating solution is an acidic coating solution.

ADVANTAGE OF THE INVENTION According to this invention, the fluctuation dispersion | variation of the local abrasion loss amount in the contact surface with a gravure plate in gravure coating can be suppressed, and the lifetime of a doctor can be extended.
Moreover, the nonuniformity of the amount of doctor wear generated during the continuous coating can be reduced, and the generation of coating stripes can be suppressed.

It is sectional drawing which shows one specific example of the coating apparatus of the gravure coating system which uses the doctor of this invention. It is sectional drawing which shows the other specific example of FIG. 1 of the application | coating apparatus of the gravure coating system which uses the doctor of this invention. It is sectional drawing which shows one specific example which shows the gravure plate of the gravure coating system which uses the doctor of this invention, and a doctor. It is sectional drawing which shows the other specific example of FIG. 3 which shows the gravure plate of the gravure coating system which uses the doctor of this invention, and expansion of a doctor. It is sectional drawing which shows one specific example of the shape of the doctor of this invention.

In order to achieve the above-mentioned target, the present invention provides a mounted portion 20 and a blade protruding from the mounted portion 20 in a thin plate shape with a thickness T2 smaller than the thickness T1 of the mounted portion 20. A gravure doctor 3 having a portion 22.
The attached portion 20 is a place to be attached to the doctor holder 4.
The length L1 in the direction in which the blade portion 22 protrudes from the attached portion 22 is 1.5 mm or more and 3.0 mm or less, and the Vickers hardness of the surface of the blade portion 22 is 920 Hv or more and 1500 Hv or less. And
By having such a configuration, the blade portion 22 is given a bend, the frictional force between the gravure plate and the doctor is reduced, and the uniform contact with the gravure plate is maintained. Furthermore, the amount of wear can be reduced by the cutting edge 22A of the blade portion 22, and the variation in the amount of wear can be suppressed because the absolute amount of wear is small. Thereby, the application | coating stripe which generate | occur | produces by the difference in the amount of local wear can be suppressed.

  The doctor of this invention is demonstrated in detail, referring drawings below along embodiment. 1 to 5 show a specific example of the present invention.

  FIG. 1 shows a specific example of a gravure coating type coating apparatus using the doctor of the present invention. As shown in FIG. 1, the doctor of the present invention has a coating liquid stored in the ink pan 2 that is scraped up by the rotation of the plate cylinder 1, and the scraped coating liquid comes into contact with the doctor 3 to obtain an appropriate amount. Become. Accordingly, the uniform coating film 7 can be formed on the base material 5 by uniformly adhering the gravure plate which is the plate surface and the blade edge 22A of the blade portion 22 of the doctor 3 to each other.

  FIG. 3 is a specific example showing an enlarged portion where the gravure plate and the blade edge 22A of the doctor 3 are in contact with each other. Usually, the plate cylinder 1 is formed of a base material 12 and a surface treatment layer 13 constituting a plate surface.

  As the base material 12 of the plate cylinder 1, cylindrical carbon steel or stainless steel that is relatively easy to process is usually used in order to increase processing accuracy. And since it is necessary to give precise engraving, a material with good workability, for example, low carbon steel of about S20C to S30C is desirable.

  When applying a coating solution with high acidity, it is preferable to use stainless steel for the base material of the plate cylinder 1, and it is preferable to apply Cr plating to the surface in order to prevent wear.

  In the present invention, the size, shape, and the like of the base material 9 that forms the doctor 3 are not particularly limited, but the shape of the general doctor 3 is such that the thickness T1 of the attached portion 20 shown in FIG. .Blade steel plate having a width of about 10 mm to 0.60 mm and a width of about 40 to 80 mm, and a blade portion 22 for scraping off the coating solution is formed on one or both ends. The material of the base material 9 of the doctor 3 is mild steel, stainless steel, plastic or the like, but steel material having high processing accuracy, elasticity and toughness is most preferable.

  In the present invention, as shown in FIG. 5, the length L1 of the blade portion 22 is in the range of 1.5 mm or more and 3.0 mm or less, and the Vickers hardness of the surface of the blade portion 22 is 920 Hv or more and 1500 Hv or less. Features. If this range is satisfied, coating streaks and the like can be suppressed by reducing the contact at the blade portion 22 and the gravure plate.

  In addition, the thickness T2 of the blade portion 22 of the doctor 3 is desirably 0.05 mm or more and 0.20 mm or less, and the pressure applied to the blade edge 22A can be reduced. If the thickness T2 of the blade portion 22 of the doctor 3 is less than 0.05 mm, sufficient pressure cannot be applied to the plate surface due to insufficient strength of the blade edge, and the contact state is biased when contacting the plate surface. Will result in uneven wear. When the thickness T2 of the blade portion 22 of the doctor 3 exceeds 0.20 mm, the doctor is not sufficiently bent, the resistance increases when contacting the plate surface, and the contact state is biased, resulting in wear resistance. A uniform state is produced.

Further, the mounted portion 20 and the blade portion 22 have a common base material 9, and the blade portion 22 further has a surface layer 24 that covers the surface of the base material 9.
Here, the thickness of the base material 9 of the blade portion 22 is 0.049 to 0.199 mm, and the thickness of the surface layer 24 is 0.001 to 0.05 mm.
The surface layer 24 is formed by laminating an inorganic particle-dispersed composite plating layer containing uniform ceramic particles on the base material 9, and examples of the ceramic particles include Al ₂ O ₂ , SiO ₂ , SiC, TiN, and the like. It can be illustrated. The inorganic particle-dispersed composite plating containing ceramic particles is preferably a Ni-P-based plating in which SiC is dispersed. Furthermore, it is desirable that the particle size be 0.5 to 5.0 μm, and hardness variations in the width direction of the doctor can be suppressed.

  Next, FIG. 4 is another specific example showing an enlarged portion where the gravure plate 1 and the doctor 3 are in contact with each other.

The gravure plate is formed by the base material 12 and the plating 13 on the surface thereof as in FIG.
Further, the mounted portion 20 and the blade portion 22 have a common base material 9, and the blade portion 22 further has a surface layer 24 that covers the surface of the base material 9.
The surface layer 24 is configured by laminating an inorganic particle-dispersed composite plating layer 24 containing uniform ceramic particles on the base material 9, and an organic material containing fluorine-based resin particles covering the inorganic particle-dispersed composite plating layer 24. The resin dispersed composite plating layer 26 is used.
The organic resin-dispersed composite plating layer 26 containing fluorine resin particles is preferably, for example, Ni-P plating in which PTFE fine particles are dispersed.

  Then, although the effect in this invention is demonstrated using an Example, this invention is not limited by the following description. In addition, the surface hardness of the surface treatment doctor by an Example and a comparative example was measured with the Vickers hardness meter.

<Example 1>
The doctor 3 is obtained by applying Ni-P plating 24 in which SiC is dispersed to the mild steel base material 9. The thickness T1 of the attached portion 20 was set to 0.15 mm. A blade 22 having a length L1 of 1.5 mm and a thickness T2 of 0.09 mm was machined at one end of the doctor 3 having a width of 60 mm and a length L2 of the doctor 3 of 1550 mm. The doctor 3 with a steel blade having a surface hardness of 950 Hv was obtained. Using this doctor 3, application processing was performed with a gravure coater.
As coating conditions, a solvent-diluted acidic solution having a viscosity of 2 mPa · s was used as the coating solution, and continuous coating was performed for 180 minutes. As a result, there was no generation of coating streaks, and a good product could be manufactured stably.

<Example 2>
Under the same coating conditions as in Example 1, the mild steel base material 9 is subjected to Ni-P plating 24 in which SiC is dispersed to obtain the doctor 3. The thickness T1 of the attached portion 20 was set to 0.15 mm. A blade 22 having a length L1 of 1.6 mm and a thickness T2 of 0.09 mm was machined at one end of the doctor 3 having a width of 60 mm and a length L2 of the doctor 3 of 1550 mm. The doctor 3 with a steel blade having a surface hardness of 950 Hv was obtained. Using this doctor 3, application processing was performed with a gravure coater. As a result, there was no generation of coating streaks, and a good product could be manufactured stably.

<Comparative Example 1>
Under the same coating conditions as in Example 1, the mild steel base material 9 is subjected to Ni-P plating 24 in which SiC is dispersed to obtain the doctor 3. The thickness T1 of the attached portion 20 was set to 0.15 mm. A blade 22 having a length L1 of 1.4 mm and a thickness T2 of 0.09 mm was machined at one end of the doctor 3 having a width of 60 mm and a length L2 of the doctor 3 of 1550 mm. The doctor 3 with a steel blade having a surface hardness of 900 Hv was obtained. Using this doctor 3, application processing was performed with a gravure coater. As a result, a coating streak that could be visually confirmed occurred during the continuous coating, and a good product could not be obtained.

<Comparative example 2>
Under the same coating conditions as in Example 1, the mild steel base material 9 is subjected to Ni-P plating 24 in which SiC is dispersed to obtain the doctor 3. The thickness T1 of the attached portion 20 was set to 0.15 mm. A blade 22 having a length L1 of 1.4 mm and a thickness T2 of 0.09 mm was machined at one end of the doctor 3 having a width of 60 mm and a length L2 of the doctor 3 of 1550 mm. The doctor 3 with a steel blade having a surface hardness of 950 Hv was obtained. Using this doctor 3, application processing was performed with a gravure coater. As a result, a coating streak that could be visually confirmed occurred during the continuous coating, and a good product could not be obtained.

<Comparative Example 3>
Under the same coating conditions as in Example 1, the mild steel base material 9 is subjected to Ni-P plating 24 in which SiC is dispersed to obtain the doctor 3. The thickness T1 of the attached portion 20 was set to 0.15 mm. A blade 22 having a length L1 of 1.5 mm and a thickness T2 of 0.09 mm was machined at one end of the doctor 3 having a width of 60 mm and a length L2 of the doctor 3 of 1550 mm. The doctor 3 with a steel blade having a surface hardness of 900 Hv was obtained. Using this doctor 3, application processing was performed with a gravure coater. As a result, a coating streak that could be visually confirmed occurred during the continuous coating, and a good product could not be obtained.

  Table 1 shows the results of measuring the wear width of the doctors used in Examples 1 and 2 and Comparative Examples 1, 2, and 3, and the results of coating processing. In addition, the measuring method of the wear width of a doctor and the evaluation method of a coating process are as follows.

<Wear width measurement method>
For the doctor after 180 minutes of continuous application, the cutting edge part 22A in contact with the gravure plate is observed with a microscope, the wear width from the tip part to the scraped part is measured at 7 points in the width direction, and the average value is calculated. It was set as the wear width.

<Evaluation method of coating process>
The sample subjected to the coating process was visually evaluated. As a result of visual evaluation, double circles (◎) indicate that no coating streaks have occurred, triangles (△) indicate that coating streaks are weak, and cross marks indicate that coating streaks are strong. (X).

  The doctor manufacturing method of the present invention requires high precision quality, such as optical films, electronic substrates, food packaging materials, medical packaging materials, etc., in mass production fields using gravure coating methods, stable production quality Is likely to contribute to cost reduction and higher accuracy.

DESCRIPTION OF SYMBOLS 1 ... Plate cylinder 2 ... Ink pan 3 ... Doctor 4 ... Doctor holder 5 ... Support body 6 ... Back roll 7 ... Coating film 8 ... Guide roll 9 ... Doctor base material 24 ... Inorganic particle dispersion composite plating layer 26 containing ceramic resin ... Organic resin-dispersed composite plating layer 12 containing fluororesin ... Gravure plate base material 13 ... Gravure plate surface treatment layer T2 ... Doctor blade thickness L1 ... Doctor blade length L2 ... Doctor length T1 ... Doctor attachment thickness

Claims (8)

A doctor for gravure printing having a mounted portion and a blade portion protruding in a thin plate shape with a thickness smaller than the thickness of the mounted portion from the mounted portion,
The length in the direction in which the blade portion protrudes from the attached portion is 1.5 mm or more and 3.0 mm or less, and the Vickers hardness of the surface of the blade portion is 920 Hv or more and 1500 Hv or less.
Doctor characterized by that. The attached portion and the blade portion have a common base material,
The blade part further has a surface layer covering the surface of the base material,
The blade portion has a thickness of 0.05 mm or more and 0.20 mm or less.
The doctor according to claim 1. The surface layer is composed of an inorganic particle-dispersed composite plating layer containing ceramic particles.
The doctor according to claim 1 or 2, characterized in that. The surface layer is composed of an inorganic particle-dispersed composite plating layer containing ceramic particles covering the surface of the base material, and an organic resin-dispersed composite plating layer containing fluorine-based resin particles covering the inorganic particle-dispersed composite plating layer. ing,
The doctor according to claim 1 or 2, characterized in that.   The doctor according to any one of claims 1 to 4, wherein the base material is one of soft steel, stainless steel, and plastic having elasticity and toughness.   6. An applicator for a gravure coating apparatus comprising a plate cylinder having a plate surface formed on a surface of a cylinder, and scraping off an excess coating liquid on the plate surface. A method for producing a coated product, wherein a coated film is formed on at least one surface of a support,
A method for producing a coated product, wherein a coating liquid is coated on a support that is continuously conveyed using the coating apparatus according to claim 6, and a coating film is formed on the support.   The method for producing a coated product according to claim 7, wherein the coating solution is an acidic coating solution.

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