JP2007177345A - Doctor blade - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a doctor blade which is excellent in plate rigidity important for doctor performance, in followingness to a counter roll, and in roll contact portion abrasion resistance important for production efficiency in a paper machine, and little damages the surface of the counter roll. <P>SOLUTION: The doctor blade produced from a fiber-reinforced plastic prepared by impregnating reinforcing fibers with a matrix resin is characterized in that the reinforcing fibers in the outermost layer on a counter roll-contacting side is a woven fabric, and the maximum height of surface roughness is 2 to 8 μm. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a doctor blade used for scraping off paper dust or the like adhering to the surface of, for example, a guide roll of a paper machine.

  For example, as a doctor blade for scraping off paper dust or the like adhering to the surface of various rolls of a paper machine, a metal blade or a resin blade has been conventionally used. However, when a metal blade is used, there is a problem that the surface of a plated or rubber-covered roll (hereinafter referred to as a mating roll or simply a roll) with which the blade tip contacts is easily damaged. In addition, when the resin blade is used, there is a problem in production efficiency such as a loss of equipment stoppage due to replacement of the wear blade because the blade wear is large although damage to the surface of the counterpart roll is small. In addition, the resin doctor blade itself has low bending rigidity, and the pressing linear pressure on the roll cannot be increased, so uniform adhesion to the roll cannot be obtained, resulting in a gap between the roll and the blade. And there were performance problems such as scraping leakage.

  In contrast, in recent years, those made of fiber reinforced resin composite materials have come to be used. As a fiber reinforced resin composite material, a sheet material obtained by impregnating a reinforced fiber with a thermosetting resin or a thermoplastic resin has been proposed. Usually, the length of a roll used in a paper machine is as short as 2 m, and as long as 10 m.

  As an example, Patent Document 1 discloses a fiber reinforced thermosetting in which a plain woven glass cloth base epoxy resin prepreg and a unidirectional carbon strand base epoxy resin prepreg are alternately laminated and a material made of plain woven glass cloth is thermoformed. The doctor blade which consists of the property composite sheet is proposed. In order to prevent flapping of the blade surface that comes into contact with the mating roll and peeling between the laminated reinforcing fibers, it is proposed to arrange a plain woven cloth. However, when the fabric is placed on the surface layer, unevenness of the texture portion occurs, so when using it as a doctor blade, a minute gap is created between the roll and the scraping of paper scraps etc. adhering to the roll. There was a problem that could cause.

Patent Document 2 proposes a doctor blade formed from a fiber-reinforced thermoplastic resin material in which reinforcing fibers such as glass, aramid, and carbon fiber are bonded with polyphenylene sulfide from the viewpoint of improving wear resistance. ing. However, there is a problem that there is a beard at the time of wear peculiar to the fiber-reinforced thermoplastic resin material, and there is a possibility that the beard is mixed into the papermaking product when the beard is detached.
JP 2002-173887 A (paragraph 0010) Japanese Patent Laid-Open No. 5-321189 (paragraph 0005)

  The present invention improves the above-mentioned drawbacks of the prior art, and has plate rigidity important for doctor performance, uniform adhesion to the mating roll, and wear resistance of the roll contact part important for production efficiency in a paper machine. It provides a doctor blade with little damage to the surface of the opponent roll.

In order to solve the above problems, the doctor blade of the present invention has the following configuration. That is, (1) In the fiber reinforced resin doctor blade having a laminated structure, the shape of the outermost reinforcing fiber on the side where the end cross section forms an acute angle is a woven fabric, and the maximum surface roughness of the outermost layer is A doctor blade characterized by having a thickness in the range of 2 to 8 μm.
(2) The doctor blade according to (1) above, wherein at least the resin on the surface of the outermost layer on the side where the end section has an acute angle is a thermosetting resin.
(3) The doctor blade according to any one of (1) and (2), wherein the outermost reinforcing fiber on the side where at least the end section has an acute angle is a carbon fiber.
(4) The doctor blade according to any one of (1) to (3), wherein the thickness is in a range of 0.5 to 2.0 mm.

  The doctor blade of the present invention is made of a fiber reinforced resin obtained by impregnating a matrix resin into a reinforced fiber, the shape of the outermost layer reinforced fiber on the side where the end cross section forms an acute angle, and a surface roughness. When the maximum height is in the range of 2 to 8 μm, the following effects can be obtained by using the portion having an acute end section in contact with the counterpart roll.

(B) High plate rigidity important for doctor performance (b) Uniform adhesion to the mating roll (c) Improvement of wear resistance of the mating roll contact area important for production efficiency in paper machines (d) Application to the mating roll surface Damage reduction

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, exemplary embodiments of the invention will be described with reference to the drawings. FIG. 1 is a perspective view of a doctor blade of the present invention. In FIG. 1, the end on the near side is processed obliquely, and by contacting this end with an acute angle to the roll, for example, paper dust attached to various roll surfaces of the paper machine can be scraped off. . 1a is the outermost layer on the side where the end cross section forms an acute angle. This layer is a layer in which a reinforcing fiber layer in which the reinforcing fiber form is a woven fabric is impregnated with a matrix resin, and it is necessary that the maximum height of the surface roughness is in the range of 2 to 8 μm. By having such a configuration, uniform adhesion to the counterpart roll can be achieved, and paper dust and the like adhering to the roll surface can be efficiently scraped off.

  As the reinforcing fiber, glass fiber, carbon fiber or the like can be used. When cost is regarded as important, glass fiber can be used, but it is preferable to arrange the reinforcing fiber fabric of the outermost layer (1a, 1b) from the viewpoint of the bending rigidity of the molded product. The tensile modulus of carbon fiber is preferably 230 GPa or more. From such a viewpoint, a carbon fiber woven fabric having a tensile elastic modulus of 230 GPa or more is used for the reinforcing fiber woven fabric of the outermost layer (1a, 1b), and glass fiber is used for the inner layer 2 according to the required bending rigidity. It is preferable to arrange a layer comprising reinforcing fibers and a layer comprising carbon fibers as reinforcing fibers alone or in appropriate combination.

  The matrix resin constituting the doctor blade includes thermosetting resins such as epoxy resin, phenol resin, unsaturated polyester resin, vinyl ester resin, polyimide resin and acrylic resin, polyamide resin, polyacetal resin, polyphenylene sulfide resin, polyethylene terephthalate. Polyester resins such as polybutylene terephthalate and polycyclohexanedimethyl terephthalate, polyarylate resins, polycarbonate resins, polystyrene resins, HIPS resins, ABS resins, AES resins, styrene resins such as AAS resins, acrylic resins such as polymethyl methacrylate resins, Thermoplastic resins such as imide resins such as polyetherimide and polymethacrylimide are listed. Since there is a possibility that whiskering occurs during the wear of the thermoplastic resin and the whisker is detached, it may be mixed into the papermaking product. Therefore, it is preferable to use a thermosetting resin from the viewpoint of wear characteristics. . In particular, an epoxy resin is preferably used in terms of moldability and various physical properties. You may mix | blend a flame retardant, a coupling agent, an electroconductivity imparting agent, an inorganic filler agent, etc. with these resin.

  With respect to the molding method, it is preferable to perform pressure molding represented by press molding from the viewpoint of surface smoothness. In press molding, the laminated product is sandwiched between release films, and the resin is cured and molded by heating and pressing in the mold. The surface roughness of the molded product is determined by the selection of the release film. Is done. In the case of a laminated structure in which a woven fabric is arranged on the surface layer, the maximum height of the surface roughness is lowered by applying a sand mat treatment and using a release film having a thickness of about 180 μm rather than using a smooth release film. This is preferable because it can be suppressed.

  In addition, in order to ensure the plate rigidity required for the doctor blade, it is necessary to increase the thickness. However, if the thickness is increased, the doctor performance decreases, and a high linear pressure is required to obtain uniform adhesion with the mating roll. Need to be applied. On the other hand, there is a thickness suitable for the doctor blade because the required plate rigidity cannot be ensured if the thickness is reduced. The thickness of the doctor blade of the present invention is preferably in the range of 0.5 to 2.0 mm.

  In addition, the wear amount when using the doctor blade is affected by the volume content of the total amount of reinforcing fibers constituting the blade. Further, if the blade wear is uneven, a gap is formed between the blade and the mating roll, resulting in scraping leakage. From the viewpoint of wear resistance and uniform wear, it is preferably in the range of 50 to 70%.

  Next, the manufacturing method of the doctor blade of this invention is demonstrated for every process.

(1) Prepreg manufacturing process First, a carbon fiber woven fabric and a glass fiber woven fabric are impregnated with a thermosetting resin such as an uncured epoxy resin in advance to obtain two types of prepregs.

(2) Pre-preg cutting and laminating process (bending elastic modulus adjusting process)
Each prepreg is cut into a width and length sufficient for the doctor blade to cut out. As a laminated structure, a glass fiber fabric is laminated in the direction of 0 ° / 90 °. However, it is preferable to dispose a carbon fiber fabric in the outermost layer from the viewpoint of the bending rigidity of the molded product.

(3) Hot press molding process When an epoxy resin is used as the matrix resin, it is pressed by a hot press at a temperature of 100 to 200 ° C. and a surface pressure of 0.5 to 1.5 MPa to obtain a molded mother board.

(4) Machining process Cut out to a predetermined size from the molded mother board, apply a cutting process of 15 to 45 ° to the scraper working part, and if necessary, drill a hole for fixing to the blade holder device. Get a doctor blade.

Example 1
Hereinafter, the present invention will be described more specifically based on examples. The doctor blade 1 shown in FIG. 1 is obtained by laminating a carbon fiber woven epoxy resin prepreg and a glass fiber woven epoxy resin prepreg, and performing hot press molding.

  Specifically, a woven epoxy resin prepreg composed of PAN-based carbon fibers having a tensile modulus of 230 GPa (fiber basis weight 200 g / m2), a woven epoxy resin prepreg composed of glass fibers (plain weave, fiber basis weight 280 g / m2), From the top, 1 ply of carbon fiber woven prepreg, 5 plies of glass fiber woven prepreg, and 1 ply of carbon fiber woven prepreg were sequentially laminated. Then, the preform is sandwiched between 180 μm thick polyethylene terephthalate film that has been subjected to sand matting treatment, applied with silicone, and subjected to mold release treatment. Then, using a hot press apparatus, the surface pressure is 0.7 MPa and the temperature is 120 ° C. Was held for 60 minutes to obtain a doctor blade having a thickness of 1.4 mm and a fiber volume content of 59%.

(Comparative Example 1)
Next, as Comparative Example 1, a preform was prepared with the same prepreg and laminated structure as Example 1, and sandwiched between polypropylene films having a thickness of 60 μm that had not been subjected to sand matting, and under the same pressing conditions as in Example 1. By molding, a doctor blade having a thickness of 1.4 mm and a fiber volume content of 59% was obtained.

(Comparative Example 2)
Further, as Comparative Example 2, a doctor blade having the same laminated structure as that of Example 1 was manufactured by a pultrusion method. A carbon fiber woven fabric and a glass fiber woven fabric were impregnated with an epoxy resin and passed through a mold heated to 160 ° C. to obtain a doctor blade having a thickness of 1.4 mm and a fiber volume content of 59%.

  In Example 1 and Comparative Examples 1 and 2 above, the results of measuring the maximum height of the surface roughness and the adhesion to the mating roll when the actual machine test was performed as a roll surface scraping blade in the press part of a paper machine The doctor performance is shown in Table 1. The conditions in the actual machine test were a paper making speed of 1100 m / min and a pressing linear pressure of 200 g / cm.

  As is clear from the above results, the doctor blade according to Example 1 of the present invention was excellent in surface smoothness, and thus excellent in adhesion to the counterpart roll. As a result, no scraping leakage occurred, and the doctor performance was also carried out. Example 1 was excellent.

It is a perspective view which shows one Example of the doctor blade of this invention.

Explanation of symbols

1a: outermost layer on the side where the end cross section forms an acute angle 2: inner layer

Claims (4)

In the fiber reinforced resin doctor blade having a laminated structure, the shape of the outermost reinforcing fiber on the side where the end cross section forms an acute angle is a woven fabric, and the maximum height of the surface roughness of the outermost layer is 2 to 8 μm. Doctor blade characterized by being within the range of 2. The doctor blade according to claim 1, wherein at least the resin on the surface of the outermost layer on the side where the end section has an acute angle is a thermosetting resin. The doctor blade according to any one of claims 1 and 2, wherein the reinforcing fiber in the outermost layer on the side where at least the end section has an acute angle is a carbon fiber. The doctor blade according to any one of claims 1 to 3, wherein the thickness is in a range of 0.5 to 2.0 mm.

Images