JP2006327170A - Doctor blade - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inhibit the accurrence of poor application caused by a burr by providing a doctor blade free of the generation of the burr. <P>SOLUTION: The generation of the burr which follows the progress of abrasion is inhibited by having an inclined part in the direction of the edge of the blade tip in addition to the inclined part which contacts with the printing plate at the edge of the blade tip of the doctor blade 1. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to the shape of a doctor blade that eliminates the occurrence of poor coating and scraping due to the doctor blade.

In the gravure coating method, a doctor blade is brought into contact with a gravure roll made by mechanical engraving or laser engraving to scrape off the excess coating solution and transfer the coating solution in a fine coating pool called a cell onto a film or paper. It is a coating method. Therefore, mechanical wear due to contact with the gravure roll occurs at the tip of the doctor blade. Usually, the wear piece generated by wear repeats the phenomenon that it separates from the tip of the doctor blade with the passage of time and is generated again. However, if the wear piece does not move away due to the cause of the doctor blade material, etc., the wear piece grows at the tip of the doctor blade and becomes a so-called burr and adheres to the tip. This will adversely affect the contact scratching effect and cause poor coating. The same phenomenon occurs not only in gravure coating and gravure printing but also in doctor blades used for flexographic printing and other lithographic printing methods.

The problem to be solved is to provide a doctor blade that prevents burr from occurring at the tip of the doctor blade due to contact with the plate surface or the like.

In order to achieve the above-mentioned object, the invention according to claim 1 is characterized in that the doctor blade for scraping off the coating liquid or ink has an inclined shape different from the inclined angle contacting the plate surface at the same time. A doctor blade is provided.

The doctor blade according to claim 1, wherein a material thickness of the doctor blade is 0.1 mm or more.

The doctor blade according to claim 1 or 2, wherein a material of the doctor blade is subjected to a surface treatment such as metal, resin, rubber, or plating.

The occurrence of burr due to the use of a doctor blade for an engraving roll represented by a gravure roll has been unavoidable as long as the doctor blade and the engraving roll are in contact with each other. The appearance that burr is not easily generated at the tip of the doctor blade, that is, the tip shape that the initial state of the wear piece can be easily detached from the tip of the doctor blade before the wear piece grows into burr. Therefore, it is possible to avoid scraping defects, and thereby to improve the quality stability of the coated surface and the printed surface and to reduce the replacement frequency of the doctor blade.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. As shown in FIG. 2, the tip inclined surface 2 of the doctor blade 1 is in contact with the gravure roll 3, leaving the coating liquid in a fine liquid pool called a cell on the surface of the gravure roll 3, and other surplus. Scrape off the coating solution. At this time, the tip inclined surface 2 is worn by the gravure roll 3 and changes with time as shown in FIG. 3 occur. That is, the contact surface with the gravure roll 3 starts to wear, and the wear piece starts to grow. (FIG. 3-b) The wear pieces are continuously pushed out toward the tip portion of the doctor blade by the gravure roll 3, and the wear pieces stay at the tip portion to form a burr. (FIG. 3-c) In the present invention, as shown in FIG. 1, the tip inclined surface is composed of an inclined surface having an angle θ1 that contacts the gravure roll 3 and an inclined surface having an angle θ2 that prevents the formation of wear pieces. The wear piece generated on the contact surface of the angle θ1 is pushed out to the inclined surface of the angle θ2, but the inclined surface of the angle θ2 is not a room shape to which the wear piece can be attached. It leaves from the inclined surface of θ1. With the tip shape of the present invention, even if wear progresses, burr does not occur, so that application failure can be prevented.

The material thickness of the doctor blade is suitably 0.1 mm or more. If it is 0.1 mm or less, the bending of the tip of the doctor blade when pressed against the plate surface becomes too large, and the surface of the plate is stroked, so that the scraping effect cannot be obtained.

Further, as a material type, a carbon tool steel plate, a stainless steel plate, or a surface-treated product using these as a base material is generally used, and any of them has a scraping effect due to the spring property of a thin plate. Since plastic or rubber is softer than a metal material, there is an advantage that damage to the plate due to contact can be eliminated.

Examples and comparative examples

A doctor blade was created according to the specifications in Table 1, and the presence or absence of burr was confirmed. In the embodiment of the present invention, the cell shape of the gravure roll made of hard chrome plating is a slanted line type, the density is 80 lines / inch, the rotation speed of the gravure roll is 200 m / min, the linear pressure of the doctor blade is the blade material is SK4 It was 0.5 kg / cm, and when the blade material was polyester, it was 0.3 kg / cm, and the operation was performed for 1 hour. In the examples, θ1: 20 ° and θ2: 30 ° were set, and in the comparative example, θ1: 20 ° was set, and the occurrence of burring was investigated without θ2, and the results are shown in Table 1.

In the case of the tip shape having the inclined surface θ2 for preventing burr occurrence in Examples 1 and 2, burr was not generated in any case, and a good scraping effect was continued. Wear on the inclined surface θ1 due to contact with the roll had progressed, but there were no wear pieces that caused burr at the boundary between the inclined surface θ1 and the inclined surface θ2.

In Comparative Examples 1 and 2, it was confirmed that burr was generated at the tip of the inclined surface θ1 in any case. This is because there is no inclined surface θ2 to prevent burr occurrence, so the wear piece is brought close to the tip of the blade edge and continues to grow due to the appearance of continuous wear pieces that are not interrupted. is there.

It is an enlarged view of the front end side surface of a doctor blade. It is a side view in which the doctor blade is contacting the gravure roll. It is the figure which showed the time-dependent change of burr generation. (A) at the start of use, (b) growth of wear pieces, and (c) occurrence of burr.

Explanation of symbols

1 doctor blade 2 tip inclined surface 3 gravure roll

Claims (3)

A doctor blade for scraping off a coating liquid or ink, wherein the doctor blade has an inclined shape different from an inclined angle contacting the plate surface at the same time. The doctor blade according to claim 1, wherein a material of the doctor blade is 0.1 mm or more. The doctor blade according to claim 1 or 2, wherein a material of the doctor blade is subjected to a surface treatment such as metal, resin, rubber, or plating.

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