JP3433280B2 - 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 In a papermaking dryer canvas used for high-quality paper, the surface in contact with the wet paper is required to have a smooth surface property and a soft cushioning property.

For this reason, spun yarn or multifilament yarn is used on the surface of the canvas that contacts the wet paper web.

As the prior art, for example, the actual exploitation 49
-135502, Jitsukai Sho 53-11001,
Japanese Utility Model Laid-Open No. 55-146498 and Japanese Patent Laid-Open No. 57-429.
No. 95 is known.

In Japanese Utility Model Publication No. 49-135502, a spun yarn having excellent heat resistance, abrasion resistance and acid resistance or a thin multifilament yarn is used as a surface warp and a spun yarn having a large tensile strength is used as an intermediate layer and a lower layer warp. Using multifilament yarn, bulky yarn for the surface layer weft, and rigid monofilament yarn for the intermediate layer and lower layer weft, and for the surface layer warp density,
A technique is described in which the density of the warp yarns in the other layer is less than half and the surface in contact with the wet paper has felt-like softness and smoothness.

In Japanese Utility Model Application Laid-Open No. 53-11001, a multifilament yarn is placed on the warp yarn on the upper surface of the paper contacting surface to expose the multifilament yarn on the paper contacting surface, and a monofilament yarn is placed on the warp yarn on the lower surface of the paper contacting surface. It is described that the canvas is a multi-woven canvas which is extremely excellent in stability and morphological stability.

In Japanese Utility Model Laid-Open No. 55-146498, monofilament yarns are used as warp yarns, bulk yarns such as spun yarns or multifilament yarns are used as surface weft yarns, and monofilament yarns are used as weft yarns other than the surface layer. A technique has been described in which the surface of the weft is almost completely sunk and does not appear so much on the surface, and the canvas surface is covered with a bulky weft, which is therefore highly flexible and has a large dimensional stability.

In JP-A-57-47995, a monofilament yarn is used as a warp, a monofilament yarn or a multifilament yarn is used as a weft, the weft supports a wet paper, and the warp does not come into direct contact with the wet paper. It is described that it improves.

In any of the above items, a spun yarn or a multifilament yarn is used for the surface layer on the paper contact side, and a monofilament yarn is used for the back layer on the opposite paper surface side in order to increase dimensional stability. It is described that it is possible to obtain a dryer canvas in which the surface in contact with the wet paper is soft-touch and smooth.

When the spun yarn is used, there is an advantage that it is possible to obtain a canvas which is surely smooth and has a good cushioning property. However, since the spun yarn has fluff, the fluff can be removed during use to form a wet paper. There was a problem that they adhered and became paper marks.

On the other hand, when multifilament yarn is used, there is an advantage that a canvas having good smoothness can be obtained, but there is a problem that the cushioning property is not so good.

That is, it can be said that the conventional technique has not yet embodied a canvas which has both cushioning property and smoothness and has no fluff.

Therefore, the present inventors have come to the hypothesis that if a crimpable yarn is used as a weft, a canvas with good smoothness and cushioning properties can be obtained, and this provisional arrangement is made. The present invention has been achieved as a result of intensive and specific studies.

By the way, as a result of the prior art investigation, it is found that the crimped yarn is used as the surface weft on the paper contact side.
No. 0321, and use of a non-twisted yarn in which a crimpable fiber and a thermoplastic resin are mixed in the surface layer weft is used.
2-96212.

However, none of the publications discloses at all what kind of fiber is used as the crimpable fiber, and as a practical matter, the cushioning property and the smoothness are determined based on these publications. It is impossible to make a canvas that has both fluff and fluff.

Therefore, it was examined what kind of crimpable fiber and how to use it to make a smooth canvas with a soft touch on the surface in contact with the wet paper and a good cushioning property.

[0017]

As a result, a monofilament yarn is used as a warp, and the surface weft of the paper-contacting side stretches and stretches.
By using a crimpable multifilament yarn having a ratio of at least 7.0% and a monofilament yarn for the weft yarns other than the surface layer weft yarn, the crimpable multifilament yarn is floated on the surface layer, and the crimpable multifilament yarn is obtained. By utilizing the cushioning property of the filament yarn, it was possible to obtain a smooth dryer canvas with a soft touch.

Regarding the woven design, various weaves such as double weave, triple weave, and multiple weave are possible.

However, since a crimpable multifilament yarn is used for the surface layer weft, there are some problems in rigidity and dimensional stability of the entire canvas. Therefore, monofilament yarn is used for the wefts other than the warp and the surface layer weft. As a result, the rigidity of the canvas as a whole is enhanced, and the canvas has dimensional stability.

Further, by using a monofilament yarn as the warp, the warp presses the crimped yarn at the entanglement point of the warp and the surface weft to allow the warp to sink, and the crimped yarn floats at equal intervals in other places. It was found that the cushioning property originally possessed by the crimpable yarn can be more remarkably exhibited.

It was also found that the use of polyacryl multifilament yarn as the material for the crimpable multifilament yarn makes it possible to obtain a dryer canvas having excellent chemical resistance and wet heat resistance.

It has also been found that by using a polyester monofilament thread as the material of the monofilament thread to be used, the dryer canvas has higher rigidity and excellent dimensional stability.

The present inventors have further investigated what degree of crimp the crimpable multifilament yarn used for the surface layer weft has to be effective.

As a criterion for judging the degree of crimp, the expansion / contraction rate was used. The method for measuring the expansion and contraction rate is shown below. The measurement was performed according to JIS L 1090 5.7 Stretchability A method. The greater the expansion / contraction rate, the greater the degree of crimping. The measurement procedure is as follows.

The upper end of the sample is fixed, and a load (= (2/1000) × denier number) is applied to the lower end to hang it down.

After 30 seconds, 20c from the top of the sample
Mark m (= a).

The load is increased to (1/10) × denier number, and after 30 seconds, the length (= b) from the upper end of the sample to the mark marked with is measured.

{(B−a) / a} × 100 = Expansion / contraction expansion rate (%) is calculated.

Next, a dryer canvas was trial woven using yarns having different expansion / contraction elongations according to the above-mentioned measuring method, and its performance was evaluated.

First, a dryer canvas 10 was trial-woven with a crimpable polyacrylic multifilament yarn having an expansion / contraction elongation rate of 1.9 (%) and having the structure and specifications shown in FIG.

As the warp yarn 11, a polyester monofilament yarn having a diameter of 0.4 mm is used, and the density is 68.0 yarns /
2.54 cm, the surface side weft yarn 21 is a polyacrylic multifilament crimped yarn in which 6 yarns of 200 denier are twisted, and 4 twisted yarns thereof are used. The density is 1
6.0 yarns / 2.54 cm, the diameter of the polyester monofilament for the middle layer weft 22 and the back layer side weft 23 is 0.5
mm yarn is used, and the density is 16. 0 / 2.54
It was cm.

After weaving, the dryer canvas 10 was heat set. The performance of the completed dryer canvas 10 was evaluated, but the surface-side surface of the weft yarn 21 on the surface of the canvas 10 on the paper contact side did not float so much that sufficient cushioning properties could not be obtained. This is because the crimped yarn has a small crimping degree, and it has been found that the crimping degree needs to be increased.

Then, the dryer canvas 10 was then woven with the crimpable polyacrylic multifilament yarn having the expansion / contraction elongation ratio = 7.0 (%) in the same manner as described above.

As a result, it was found that the surface-side weft yarn 21 floated on the surface of the dryer canvas 10 on the paper contact side, and sufficient cushioning properties were obtained.

Therefore, regarding the crimping degree of the crimped yarn, it was found that sufficient cushioning property of the surface can be obtained if the expansion / contraction elongation ratio is at least 7.0 (%) or more.

However, if the crimping degree is excessively increased, the strength of the entire canvas 10 may be lowered, and since the crimped yarn is used only for the surface layer weft, the canvas 10 is not used.
Since the curl may occur, it is necessary to individually judge the crimping degree by comprehensively judging the texture of the canvas 10, the material, the shape, the dimensions, etc. of the yarn to be used.

[0037]

DETAILED DESCRIPTION OF THE INVENTION A monofilament yarn is used as a warp, a crimpable multifilament yarn is used as a surface layer weft of a paper-contacting side, and a monofilament yarn is used as a weft thread other than the surface layer weft. Can be obtained.

As a result, a dryer canvas which has a cushioning property on the paper contact side and is soft-touch and smooth is formed.

When polyacrylic multifilament yarn is used as the material of the crimpable multifilament yarn, a dryer canvas having excellent chemical resistance and resistance to moist heat can be obtained.

By using a polyester monofilament thread as the material of the monofilament thread to be used, it is possible to obtain a dryer canvas which has higher rigidity and excellent dimensional stability.

Various textures such as double weave, triple weave, and multiple weave are possible.

[0042]

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

A dryer canvas 10 having a weft triple weave structure as shown in FIG. 1 is also suitable as an embodiment. The details of the dryer canvas 10 are as described above.

In this case, the expansion and contraction rate of the surface layer weft 21 is 1
It was 3.5 (%).

After weaving, the dryer canvas 10 was heat set. The obtained product had a thickness of 2.5 mm and an air permeability of 8.500 cc / min. / Cm 2.

In this embodiment, the weft has been described as a triple weave, but the present invention is not limited to this, and it is needless to say that various weaves such as double weave and multiple weave are possible.

Further, the material of the yarn to be used is not limited to polyacrylic or polyester, and a material suitable for the purpose of the dryer canvas may be properly selected.

The shape of the thread is not limited to the round thread,
For example, various types of flat yarns are possible, and the dimensions of the yarns are not limited to those in this embodiment.

The crimping degree of the crimped yarn may be appropriately determined depending on the quality of the wet paper to be dried by the dryer canvas.

[0050]

According to the present invention, by using the crimped multifilament yarn having the expansion / contraction expansion ratio of at least 7.0% only for the surface layer weft yarn on the paper-contacting surface side, excellent cushioning properties and soft touch are obtained. It is possible to obtain a smooth dryer canvas.

By using polyacryl multifilament as the material of the crimpable multifilament yarn, a dryer canvas having excellent chemical resistance and wet heat resistance can be obtained.

Further, by using polyester monofilament as the material of the monofilament thread to be used, it is possible to obtain a dryer canvas which has higher rigidity and excellent dimensional stability.

[Brief description of drawings]

FIG. 1 is a specification diagram of a dryer canvas according to an embodiment of the present invention.

Claims (2)

(57) [Claims] 1. In a papermaking dryer canvas woven using monofilament yarns as warp yarns, crimpable multifilament yarns having a stretching elongation ratio of at least 7.0% or more are used as surface layer weft yarns on the paper contact surface side, A monofilament yarn is used for the weft yarns other than the surface layer weft yarn. 2. The crimpable multifilament yarn according to claim 1, wherein the crimpable multifilament yarn is a polyacrylic multifilament yarn.
A dryer canvas for papermaking, wherein the monofilament yarn is a polyester monofilament yarn.