JP2589253B2 - Dandy roll for black watermark and papermaking method using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[Object of the invention]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dandy roll used for providing a watermark pattern in papermaking and a papermaking method using the same.

[0002]

BACKGROUND OF THE INVENTION Watermark patterns provided on paper include a black watermark and a white watermark. In the black watermark, the watermark pattern portion looks darker than the surroundings, while in the white watermark, the watermark pattern portion appears through. Things. In any case, the thickness or density of the stock web is changed in the papermaking stage to develop a watermark pattern.

[0003] Several methods have been developed for such a method. However, in a wire part during a papermaking process, a device provided with a water-permeable holding net called a dandy roll on the roll surface is a paper material. There has been proposed a method of acting on the web and giving a change in basis weight such as a change in thickness or density to a part of the stock web by unevenness having a shape corresponding to the pattern provided on the surface of the dandy roll. The technical points required for forming such a watermark include that the watermark is clearly expressed and that the watermark can be stably processed during papermaking.

However, there are the following problems in stably expressing a black watermark. That is, in order to form a black watermark, as shown in FIG. 10 (a), a concave portion 8 'having a pattern corresponding to the watermark is formed on the concave forming net roll 6' of the dandy roll 1 ', and a paper is formed in this portion. The structure is such that the material web A is concentrated and the concave-shaped net roll 6 'is supported by the lower net roll 5'.

However, in such a structure, as shown in FIG. 10 (b), the concave-shaped net roll 6 'is deformed with repeated use, and the step between the concave portion 8' and the periphery thereof becomes less clear. As a result, there is a problem that a watermark pattern that was clear at the stage of starting papermaking becomes unclear over time.

[0006]

[Technical matters attempted to be developed] The present invention has been made in view of such a background. In forming a black watermark, the present inventor prevents the deterioration over time during the papermaking of a concave-shaped net roll. The development of a new dandy roll and a papermaking method using the same was attempted.

[0007]

Configuration of the Invention

The dandy roll for black watermark according to the first invention of the present application is provided so as to enclose a lower net roll and the lower net roll, and forms a recess for forming a black watermark. And a notch portion is formed in the lower net roll in correspondence with a concave portion of the concave-shaped mesh roll, and the concave portion is formed in the notch portion from the back side. It is characterized in that it is fitted to the same.

[0008] The papermaking method using the dandy roll for black watermark according to the second invention of the present application comprises:
A concave shaping net roll formed so as to enclose the lower net roll and forming a concave portion for black watermark formation, wherein the lower net roll has a concave portion of the concave shaping net roll. A notch is formed corresponding to the above, and the change in the basis weight per 1 mm in length is 10 by using a dandy roll in which the recess is fitted to the notch from the back side.
A black watermark pattern of up to 70 g / m ² is formed on paper. It is an object of the present invention to achieve the above object.

[0009]

According to the present invention, a cut-out portion is formed in the lower net roll corresponding to the concave portion of the concave-shaped net roll, and the concave portion is fitted to the cut-out portion from the back side. When the concave-shaped mesh roll is applied to the stock web, the back side of the concave portion is not pressed by the lower mesh roll, so that the deformation of the concave portion is reduced.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the illustrated embodiments. Reference numeral 1 denotes a dandy roll to which the present invention is applied. As shown in FIG. 1, the dandy roll passes a center axis 3 through an axis of a roll main body 2 as an example, and a disc is provided at regular intervals on the center axis 3. 4 is provided to form a body, thereby adopting a structure for supporting the roll body 2. The roll body 2 includes a lower net roll 5 provided directly on the disk 4 and a concave-shaped net roll 6 provided on the lower net roll 5.

The concave shaping net roll 6 is used to form a black watermark by acting on the stock web. The roll 6 has a filament diameter of, for example, 50 to 200 μm and a diameter of 60 to 1 μm.
It is composed of a 20-mesh net, and its base surface 7 is provided with a recess 8 for forming a black watermark in a desired pattern or character.

Incidentally, as the concave-shaped mesh roll 6 of the dandy roll used for making ordinary paper, a mesh having a filament diameter of 234 to 295 μm and a mesh of 40 to 60 mesh is usually used . In this embodiment, the wire diameter is 50 to 200 μm, 6
The reason why the mesh of 0 to 120 mesh is used is to sharpen the edges of the design or character formed by the recess 8. In this case, since the filament diameter is small, there is a concern that the filament may be cut when the concave portion 8 is formed by embossing with a press machine. In a female mold having a recess of 0.5 mm or more, the corners and corners of the mold are rounded to prevent filament breakage. Phosphor bronze is most suitable as the material of the filament having such a wire diameter, but stainless steel, polyester, polyamide or the like may be used.

Next, the recess 8 formed in the concave shaping net roll 6 will be described. As shown in FIG. 1, the recessed portion 8 is continuously or fragmented by a top regulating surface 9 acting on the stock web and defining the top surface of the black watermark, and a side regulating surface 10 defining the side surface of the black watermark. It is composed.

Then, the ceiling regulating surface 9, the side regulating surface 10,
Further, as shown in FIG. 6, the outer surface of the filament 11 constituting the base surface 7 around the recessed portion 8 may have a diameter of 15 to 30% of the filament 11, for example, a sandpaper.
Polishing may be performed using -P . By the way, in the case of polishing, the smoothness of the top regulating surface 9, the side regulating surface 10, and the base surface 7 around the concave portion is enhanced, and the diameter of the filament 11 is small, so that it is easy to shape, and the formed black watermark is formed. Has the advantage that the edges of patterns and characters are sharp. The method of polishing the filament 11 in this manner is based on a wire diameter of 234 μm to 295
It is also applicable to μm filaments.

If the filament 11 is polished, its strength is reduced. To compensate for this, plating with chrome having a high Vickers hardness can be performed. For example, in the case of a wire mesh using a phosphor bronze filament having a Vickers hardness of 130 to 200 Hv, bulging, scratching, and deformation of the concave portion are performed by plating with chrome (Vickers hardness 750 to 800 Hv) of 5 to 50 μm. Can be reduced.

Next, the appearance of the recess 8 will be described. First, the ceiling regulating surface 9 in the recess 8 is flat as shown in FIG. By the way, since the concave-shaped net roll 6 is formed by rolling a concave-shaped flat net having a concave portion formed by embossing with a mold in a cylindrical shape, the ceiling regulating surface 9 in the concave portion 8 becomes a convex curved surface. As usual, in the present embodiment, the top regulating surface 9 is made flat in the process of forming the concave portion 8. This point will be described in detail in a method of manufacturing a concave-shaped mesh roll described later.

The side regulating surface 10 in the recess 8 is formed at an angle of 30 ° to 90 ° with respect to the base surface 7 as shown in FIG. It should be noted that such an angle is also meaningful in order to increase the contrast at the edges of the design or character of the black watermark.

Next, the relationship between the concave-shaped net roll 6 and the lower net roll 5 will be described. First, in the lower net roll 5, as shown in FIG. 2, a cutout portion 12 that is 10 to 20 mm larger than the concave portion 8 is formed corresponding to the concave portion 8 of the concave-shaped net roll 6. Then, when viewed from the back side of the concave portion 8 of the concave-shaped netting roll 6, that is, the concave portion 8, the convexly bulging portion is loosely fitted into the notch portion 12. I have.

Incidentally, it is a characteristic feature of the present invention to adopt a loose fitting structure of the concave portion 8 of the concave-shaped net roll 6 and the cutout portion 12 of the lower net roll as described above. Even if is used for a long time, there is no deformation of the recess 8,
By maintaining the step between the recessed portion 8 and its periphery, the sharpness of the black watermark can be ensured.

The dandy roll 1 has the above-described structure. Hereinafter, a method of manufacturing the concave-shaped net roll 6 will be described with a focus on a method of forming the recess 8. First, before starting the description of the method of manufacturing the concave-shaped netting roll 6, a mold for forming the concave portion 8 will be described. This metal mold is formed by forming irregularities on the surface of a metal plate by, for example, etching or an NC router, and can take a form of either the male mold 13 or the female mold 14 or a form having both of them.

In the male mold 13, as shown in FIG. 5 (a), a slightly raised convex working surface 13 b is formed on the convex portion 13 a for shaping the wire net into a desired shape. As shown in FIG. 5 (b), a slightly concave working surface 14b is formed in the concave portion 14a for shaping the wire net into a desired shape. The rise and fall of the working surface 13b of the male mold 13 and the depression of the working surface 14b of the female mold 14 are:
It is directly related to the shape of the recessed portion 8 in the intaglio-shaped net roll 6, and is also related to the sharpness of the black watermark.

Here, taking the male mold 13 as an example, the swelling of the working surface 13b in the male mold 13 will be described. When the working surface 13b of the male mold 13 is slightly raised, the depression 8
In FIG. 5A, the top regulating surface 9 in the shape of the top is slightly concavely adjusted, that is, a shape in which a concave curve is drawn, and this is wound in a roll shape so that the concave portion 8 is on the outside. In addition, the depression of the ceiling regulating surface 9 is deformed so as to approach a plane. Therefore, the swelling of the working surface 13b of the male mold 13 is adjusted when the flat mesh formed with the recessed portion 8 is wound around the lower mesh by embossing with the male mold 13.
Are set to be substantially flat by deformation. By the way, since the top regulating surface 9 of the recess 8 becomes substantially flat in a state of being wound on the lower net, the stock web can be present in the recess 8 with a substantially uniform thickness. Can be prevented.

The rise and fall of the working surface 13b of the male mold 13 is determined by the width of the recess 8 and the diameter of the dandy roll 1 (= the diameter of the concave mesh roll 6). Although it is generally difficult to express by numerical values or the like, as one guide for defining the swelling state of the working surface 13b, as shown in FIG. 4, the radius of the concave-shaped net roll 6 is r, and the depth of the concave portion 8 is a. And the working surface 13
What is necessary is just to make the cross section of b bulge so that the cross section substantially follows the curve represented by x ² + y ² = (r−a) ² . still,
The same applies to the determination of the recessed state of the working surface 14b in the female mold 14.

As described above, the corners 15 and 16 of the mold are slightly rounded so that the net is not cut during embossing when a thin filament is employed. ing.

The above is the schematic structure of the mold, performing the embossing work with such a mold. That is, first, as shown in FIG. 6, a flat screen 18 is prepared, this is placed on a rubber sheet G, and the polished portion of the flat screen 18 is placed on the working surface 13 of the mold.
The male mold 13 or the female mold 14 is placed and set so as to coincide with b or 14b. Then, in this state, the mold is pressed by using a press machine or the like, so that the recess 8 is formed in the flat net 18. In addition, the flat net 18 having the concave portion 8 formed thereon is
9 is defined. By the way, in such a state of the concave shaped flat screen 19, the ceiling regulating surface 9 in the concave portion 8 has a bulge or depression of the working surface 13b or 14b in the male mold 13 or the female mold 14 as shown in FIG. It is in a depressed state.

[0026] Such a concave-shaped flat net 19 is formed by the lower net roll 5.
The lower mesh roll 5 is formed with a cutout portion 12 which is a feature of the present invention in advance at a position corresponding to the concave portion 8 of the concave-shaped net 19. Then, the concave-shaped net 19 is wound around the notch portion 12 so that the convex portion on the back side of the concave portion 8 fits into the concave-shaped net roll 6. As a result, the state of the depression of the ceiling regulating surface 9 in the recess 8 is corrected, and the state becomes substantially flat. In addition, the notch 12 is formed by the concave-shaped mesh roll 6.
It may be formed after the state described above.

Next, the formation of a black watermark using the dandy roll 1 to which the concave-shaped net roll 6 is applied will be described. Such a dandy roll 1 may be handled in the same manner as a normal watermark forming operation. As shown in FIG. 1, the base surface 7 of the dandy roll 1 faces the stock web A at a constant pressure. The recess 8 is made to act on the stock web A while rotating 1. At this time, since the concave portion 8 is fitted to the notch portion 12 from the back side according to the present invention, the concave portion 8 is not pressed by the lower mesh roll 5, and thus the deformation of the concave portion 8 is reduced. .
The rotation of the dandy roll 1 can be driven by a separate drive unit in accordance with the wire speed, in addition to the natural drive by friction with the wire.

As a result, part of the stock web A where the base surface 7 of the dandy roll 1 has acted escapes into the recess 8, and the web thickness and density of the recess 8 become higher than those of the other portions. . By drying in this state, a black watermark is formed. Here, in order to form a clear black watermark, the change in basis weight between the black watermark portion and the other portions is 10 to 7%.
It is preferably 0 g / m ² . Further, since the ceiling regulating surface 9 in the concave portion 8 can be made substantially flat, a black watermark having no continuous gradation expression of 0.25 to 25 cm ² can be performed.

[0029]

In order to confirm the effect of the present invention, an example of the present invention was compared with a comparative example. <Example 1> A phosphor bronze 65-mesh plain weave net was placed between a rubber sheet and a stainless steel mold having a convex portion having a height of 0.8 mm by etching, and a press machine of 30 kg / cm ² was used. The embossing was performed with pressure.

After attaching the lower mesh of phosphor bronze 14 mesh to the dandy roll, the mesh at the position corresponding to the embossed portion of the concave shaped flat mesh is 10 to 20 mm from the outer periphery of the embossed pattern.
It was cut off at the knuckle part of the net so that it became larger. Thereafter, a concave-shaped net roll was attached to the outer periphery of the dandy roll so that the concave portion of the embossed flat-plate net was positioned at the position of the notch of the lower net. Using this dandy roll, L
Papermaking was carried out at a rate of 65 g / m ² using a stock web having a BKP of 100 parts and a freeness of 55 ° SR.

<Comparative Example 1> After a lower mesh of phosphor bronze 14 mesh was attached to a dandy roll, the embossed concave-shaped flat mesh of Example 1 was attached to the outer periphery of the dandy roll.
Using this dandy roll, papermaking was carried out at a rate of 65 g / m ² using a stock web having an LBKP of 100 parts and a freeness of 55 ° SR. Table 1 shows a comparison between Example 1 and Comparative Example 1.
Summarized in

[0032]

[Table 1] Example 1 Comparative Example 1 Notch of lower mesh Yes No Depth of depth before use 0.56mm 0.54mm Depth of depth after 4 days use 0.55mm 0.45mm Clearness of watermark immediately after use ○ ○ Watermark sharpness after 4 days use ○ △

As shown in Table 1, according to the present invention, the deformation of the concave portion due to the use of the dandy roll can be prevented, and a clear black watermark can be stably applied to the paper for a long period of time.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a use state of a black watermark dandy roll of the present invention.

FIG. 2 is a cross-sectional view showing, on an enlarged scale, an upper side view of the same and an arrow section of the same.

FIG. 3 is an explanatory diagram showing a range of a forming angle of a side regulating surface in a concave portion.

FIG. 4 is an explanatory diagram showing, by symbols, a radius dimension of a concave-shaped net roll and a depth dimension of a concave portion.

FIG. 5 is an explanatory view showing a state in which a concave portion is formed by a male mold and a female mold, and when the concave portion is wound into a roll, the ceiling regulating surface becomes flat.

FIG. 6 is an enlarged cross-sectional view showing a state where a portion of a flat net to be black-marked is polished with sandpaper.

FIG. 7 is a cross-sectional view showing a state where the polished flat net is set on a rubber sheet.

FIG. 8 is a cross-sectional view showing a state in which a recess is formed in the flat mesh.

FIG. 9 is a cross-sectional view showing a state in which the concave-shaped flat net is wound in a roll shape on a lower net roll having a cutout portion.

FIG. 10 is a cross-sectional view showing a problem of a conventional dandy roll in which a notch is not formed in a lower mesh roll.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Dandy roll 2 Roll main body 3 Center axis 4 Disk 5 Lower net roll 6 Concave shaped net roll 7 Base surface 8 Depression 9 Top regulation surface 10 Side regulation surface 11 Filament 12 Notch 13 Male 13a Convex portion 13b Action Surface 14 Female mold 14a Depressed portion 14b Working surface 15 Corner ridge 16 Corner corner 18 Flat net 19 Concave shaped flat net A Paper web G Rubber sheet P Sandpaper

Claims (2)

(57) [Claims] 1. A lower net roll comprising: a lower net roll; and a concave shaping net roll provided to enclose the lower net roll and forming a concave portion for forming a black watermark. A dandy roll for black watermark, wherein a notch portion is formed corresponding to a concave portion of the concave-shaped net roll, and the concave portion is fitted to the notch portion from the back side. 2. A lower net roll comprising: a lower net roll; and a concave-shaped net roll provided to surround the lower net roll and forming a concave portion for forming a black watermark. A notch is formed corresponding to the concave portion of the concave-shaped net roll, and a length of 1 is used by using a dandy roll in which the concave portion is fitted to the notch from the back side.
A papermaking method using a dandy roll for black watermark, wherein a black watermark pattern having a basis weight change of 10 to 70 g / m ² per mm is formed on paper.