JP3529217B2 - Dryer canvas for papermaking - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a papermaking dryer canvas used in a dry part of a papermaking machine.

[0002]

2. Description of the Related Art A dryer canvas for papermaking used for high-quality paper is required to have a soft-touch surface on the surface in contact with the wet paper and be smooth. For this reason, the surface of the canvas used for high-quality paper that comes in contact with the wet paper is
Spun yarn or multifilament is used.

The prior art includes, for example, 1) No. 49-135502, 2) No. 53-1110.
No. 01, 3) Japanese Utility Model Laid-Open No. 55-146498 and 4 ) JP-A-57-42995 are known.

1) In Japanese Utility Model Publication No. 49-135502, a spun yarn or a multifilament thin yarn having excellent heat resistance, abrasion resistance and acid resistance is used as a surface warp and a tensile strength is used for an intermediate warp and a lower warp. Large spun yarn or multifilament is used, bulky yarn is used for surface weft, rigid monofilament is used for intermediate layer weft and lower layer weft, and surface warp density is less than half of other layer warp density. There is described a canvas in which the surface contacting with is made felt-like, flexible and smooth.

2) In Japanese Utility Model Application Laid-Open No. 53-11001, a multifilament is used by exposing it on the paper-contacting surface of the upper-layer paper-contacting surface, and a monofilament is used on the lower-layer anti-paper-bonding surface. A multi-woven canvas is described which has very good properties, breathability and morphological stability.

3) In Japanese Utility Model Publication No. 55-146498, a monofilament is used as a warp, a bulky yarn such as a spun yarn or a multifilament is used as a surface layer weft, and a monofilament is used as a weft thread other than the surface layer. There is described a canvas in which the warp is almost sunk in the surface weft and hardly appears on the surface, and the surface of the canvas is covered with a bulky weft, which is rich in flexibility and has large dimensional stability.

4) In JP-A-57-42995, a monofilament is used for the warp, a monofilament or a multifilament is used for the weft, and the wet paper is supported only by the weft so that the warp does not come into direct contact with the wet paper. Describes a canvas that has a longer life.

[0008]

In all of the dryer canvases 1 to 4 described above, a spun yarn or multifilament is used on the surface layer of the paper-contacting surface side for smoothing with a soft touch, and the back layer of the paper-contacting surface side is not used. Describes the use of monofilaments for greater dimensional stability.

However, each of 1 to 4 has a two-layer or three-layer design, and there is a problem that the amount of yarn used increases and the time required for weaving increases, resulting in an increase in cost. It was

Further, conventionally, as a multi-cylinder dryer for paper making, an upper and lower canvas system in a dryer having an upper and lower two-stage arrangement has been generally used, and a single run canvas system has been used as an improvement plan thereof, and more recently, In order to deal with high-speed papermaking of 1000 m / min to 1500 m / min, as a proposal for improving the single run system, for example, the Berlan system (trademark of Beloit, USA), the Simlan system (trademark of Valmet, Finland), etc. have been proposed. There is.

In the upper and lower canvas system, as shown in FIG. 3, a plurality of drying cylinders 51 ... Are arranged in two upper and lower stages, and the upper and lower drying cylinders 51, 51 are provided with two upper and lower canvases 1.
Nos. 0 and 10 are stretched via guide rollers 53, 53, and the wet paper 54 is sequentially guided to the upper and lower drying cylinders 51, 51 in a zigzag manner.

In the single run system, as shown in FIG. 4, a plurality of drying cylinders 51 ... Are arranged in two upper and lower stages, and one canvas 10 is sequentially stretched in a zigzag pattern between the upper and lower drying cylinders 51, 51. The wet paper 54 is guided and run by the canvas 10.

In the single run system, there is no so-called free run portion between each group or between cylinders, the high speed running of the wet paper is stabilized, and the draw (a slight tension in the running direction is applied to the wet paper. Since it is possible to control the shrinkage of the wet paper over the entire width during drying, it is possible to improve the paper quality. Further, it is possible to improve the drying efficiency by eliminating the dryer pocket (56 in FIG. 3) that was the cause of water unevenness in the machine width direction in the upper and lower canvas system.

In the single run system having such an arrangement and structure, the following problems occur when the dryer canvas used in the conventional drying section is used.

That is, the single run system controls the shrinkage ratio of the wet paper by eliminating the free run portion,
When the canvas is thick, the bending direction of the wet paper is continuously alternated while the wet paper is in contact with the same canvas, so tension and slack are alternately applied to the wet paper, reducing the merit of controlling the shrinkage ratio. It will be. Therefore, in the single run system, it is desirable that the thickness of the canvas is as thin as possible.

The dryer canvas of the three-layer structure described in the above-mentioned prior art will be examined, for example, the dryer canvas 30 of the three-layer structure shown in Table 1 below.

[0017]

[Table 1]

As the warp yarns 31 exposed only on the PS side, four twisted acrylic spun yarns of 6 count are used, and as the warp yarns 32 exposed only on the BS side, a polyester monofilament having a diameter of 0.55 mm is used. Used with a density of 76.
The number was 0 / 2.54 cm.

Acrylic spun yarn 6 is used as the PS side weft yarn 41.
Using 4 twisted yarns, the middle layer and BS side weft 4
2 has a polyester monofilament diameter of 0.55 m
Use the m one and the density is 12.5 × 3 / 2.54c
It was m.

After weaving, the dryer canvas 30 was heat set. The product obtained has an air permeability of 2,800c.
c / min. / Cm ² , the thickness was 3.9 mm.
The air permeability is a value obtained by converting the amount of air that has passed through a hole having a water column of 12.7 mm and a measurement area of 10 cm ² in one minute using a measuring instrument in accordance with JIS L1005 Brasile type method per unit area. .

The thickness of the dryer canvas 30 is 3.
It has a length of 9 mm, which is too thick to be used in the single-run system.

By the way, in considering the structure of the canvas, it is necessary to consider the relationship with the joint portion in addition to the above-mentioned surface property and air-drying property. In a loop type joint that is widely used, the warp yarn of the canvas body is folded back at both ends of the canvas to form a joining loop, the joining loops at both ends are combined, and the joining core wire is inserted into the common hole. If all canvas warp yarns are spun yarns or multifilaments, the splicing loops will also be spun yarns or multifilaments, but when inserting splicing core wires into the common holes of the splicing loops, the spun yarns or multifilaments should be soft. Since it is easily deformed and the width of the canvas is several meters, it is often difficult to insert the splicing core wire into the work, which often takes time. Therefore, in relation to the joint portion, it is desirable that at least the joining loop forming warp be made of a monofilament having shape stability.

[0023]

In order to solve the above-mentioned problems, if a single-layer woven fabric is used instead of a two-layer or three-layer structure, it can be used in a single run system and cost reduction is possible. I thought that it might be possible, and studied earnestly about the possibility of single layer weaving.

[0024] Therefore, the organization of the woven single layer shown in FIG. 2, the warp
Is a long crimped weave design and has the specifications shown in Table 2, and the warp yarns 1 appearing on the paper contact side (hereinafter referred to as PS side) 1
1 (1 to 4) is used by twisting four 6th acrylic spun yarns, and the diameter of the polyester monofilament is 0 for the warp yarns 12 (5 to 8) exposed on the non-contact side (hereinafter referred to as the BS side). Use 0.55mm, polyester monofilament diameter 0.90m for wefts 21 and 22
A dryer canvas 10 of m.

[0025]

[Table 2]

However, when the surface property after weaving was confirmed,
It was found that the weft yarn 22 at the portion shown in A portion of FIG. 2 came to float on the front surface side, and the paper-contacting surface of the canvas 10 was entirely uneven.

This is a warp yarn 1 using acrylic spun yarn.
It was found from No. 1 that the cause was that the weft yarn 22 was raised to the front side.

Therefore, how to eliminate this unevenness was examined and tests were conducted.

As a result, as shown in FIG.
By making the size (diameter) of the weft yarn smaller than that of the weft yarns 21 other than the A part weft yarn, that is, by making the weft yarns of large size and small size alternate, the weft yarn 22 floats on the PS side. It was found that the surface of the canvas 10 was eliminated, and that the surface of the canvas 10 was smooth and the surface in contact with the wet paper had a soft touch and was smooth.

It was also found that the canvas can be made thin because the unevenness is eliminated by the single layer weaving, and there is no problem even if it is used in the single run system.

It was also found that the design is a single layer, the amount of yarn used is small, the time required for weaving can be shortened, and the cost does not increase.

That is, according to the present invention, a dryer canvas for papermaking composed of warp yarns and weft yarns has a single layer weave and the warp yarns are long.
A woven texture that is crimped , with a long crimp on the paper-contacting side
Using the spun yarn warp yarns, Rongukuri counter-contact paper side
And warps lamp, using each monofilament on all weft and be long crimp on the contact paper side
For papermaking, characterized in that the size of the weft yarn at the position where the warp yarns are entangled so as to be arranged on the side opposite to the weft yarns is smaller than the size of other weft yarns so as to maintain the smoothness of the paper-contacting face. It is a dryer canvas.

[0033]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention is as shown in FIG. In other words, it has a single-layer weave design with long warp threads.
The crimping weave design, warp yarns 11 (1
~ 4) using a spun yarn, the warp yarn 12 exposed on the BS side
Using monofilaments for (5-8), wefts 21 and 2
2 is a monofilament, and the size (diameter) of the weft yarn 22 is smaller than that of the weft yarn 21.

As a result, the warp 11 exposed on the PS side is a spun yarn, and the warp has a long crimp.
Since it is a woven fabric, a canvas with a soft touch surface that comes into contact with the wet paper can be obtained.

As the material of the yarn to be used, it is desirable to use polyester monofilament for the monofilament and acrylic spun yarn having high resistance to moist heat for durability because it has high abrasion resistance and dimensional stability. .

However, it goes without saying that threads made of other materials can be used depending on the application of the canvas.

Since a monofilament is used for the warp 12, the warp can be folded back at the end to form a joining loop and a joint can be formed. Therefore, the canvas body and the joint have the same thickness and the same structure. A compact joint can be obtained.

[0038]

Embodiments of the present invention will now be described with reference to the drawings.

A dryer canvas 10 was woven as a long crimp weave having a single-layer weave design as shown in FIG. 1 and a warp yarn of 1/3. The specifications are shown in Table 3.

[0040]

[Table 3]

The warp yarns 11 (1 long crimp on the PS side
For 4 to 4), 4 twists of 6th acrylic spun yarn are used, and the warp yarn 12 (5 to 5) that long crimps to the BS side is used.
8) Polyester monofilament diameter 0.55
mm was used and the density was 76.0 lines / 2.54 cm.

Polyester monofilament having a diameter of 0.55 mm is used for the A part weft yarn 22, and the A part weft yarn 2
For the weft yarns 21 other than 2, those having a polyester monofilament diameter of 0.90 mm are used, and the density is 13.0 yarns /
It was 2.54 cm.

That is, the portion A shows a portion where the warp 11 is woven under the weft 22. Therefore, the weft has a large size (weft 21) and a small size (weft 22).
Will be woven alternately.

After weaving, the dryer canvas 10 was heat set. The product obtained has an air permeability of 3,800c.
c / min. / Cm ² , the thickness was 2.7 mm.

As for the surface property of the entire canvas 10, one having no unevenness was obtained. That is, a product having a soft touch surface which was in contact with the wet paper was obtained.

Although the thickness of the dryer canvas 30 in the example shown in Table 3 described in the section of the prior art is 3.9 mm, the thickness of the dryer canvas 10 shown in this embodiment is 2.7 mm, We were able to significantly reduce the thickness. This is a thickness within the range where there is no problem when used in the single run method.

Further, the warp 12 was folded back at the end of the dryer canvas 10 to form a joining loop, and a joint (not shown) could be formed.

An endless dryer canvas can be obtained by joining the created joints to both ends of the dryer canvas 10.

The size of the weft yarns 21 and 22 is not limited to this embodiment, and may be appropriately determined according to the specifications of the canvas, the material and size of the yarn, and the like.

[0050]

EFFECT OF THE INVENTION According to the present invention, the warp of the single layer woven fabric is long.
Since the crimped woven structure is used and the spun yarn is used as the warp exposed on the paper-contacting surface side, there is an effect that a soft surface property can be obtained.

Further, since the size of the weft yarn lifted by the warp spun yarn is made relatively small, a convex canvas is not formed on the canvas paper surface due to the weft yarn, and a canvas having excellent surface smoothness is obtained. Was given.

Furthermore, since it is a single-layer weave and has no irregularities, the thickness of the canvas is thin, and there is an effect that it can be used in the single run system without any problem.

Further, since the monofilament is used for the warp, the warp can be folded back at the end and the joint can be formed as a joining loop, so that the joint has the same thickness, structure, etc. as the main body and is compact. There is also an effect that can be created.

[Brief description of drawings]

FIG. 1 is a sectional view of a papermaking dryer canvas showing an embodiment and examples of the present invention.

FIG. 2 is a cross-sectional view of a papermaking dryer canvas examined in the course of reaching the present invention.

FIG. 3 is a side view of an upper and lower canvas type dryer part.

FIG. 4 is a side view of a single run type dryer part.

[Explanation of symbols]

10 Papermaking dryer canvas 11,12 warp 21,22 weft

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) D21F 7/08

Claims (2)

(57) [Claims] 1. A papermaking dryer canvas composed of warp and weft has a woven structure of a single-layer weave in which the warp has a long crimp , and the spun yarn is used as the long crimp warp on the paper-contacting side, and the long side is opposite to the paper-contacting side. Warp to crimp ,
Monofilaments are used for all wefts, and the size of the wefts at the position where they are entangled so that the long crimp warp on the paper contact side is arranged on the side opposite to the weft, and the smoothness of the paper contact side is adjusted. A paper dryer dryer, which is smaller than other weft yarns to maintain its size. 2. Acrylic spun yarn is used as the spun yarn for the long crimp warp on the paper-contact surface side, and the acrylic spun yarn is used on the opposite paper-contact surface side.
2. The dryer canvas for papermaking according to claim 1, wherein the monofilaments used for the long crimp warp and all the wefts are polyester monofilaments.