JPH09209288A - Dryer canvas for paper-making - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a canvas for paper-making excellent in heat resistance and having a long life by using a polethyleneterephthalate yarn, at least a part of warp and/or weft, containing unreacted carbodiimide compound and a thermoplastic polymer not containing fluorine atom. SOLUTION: A monofilament of polyethyleneterephthalate containing unreacted carbodiimide compound and a thermoplastic polymer not containing fluorine atom having a circular section of 0.1-2.0mm diameter or flat cross section having 0.3-1.3mm of long side and the ratio of short side: long side is l:1.4-1:4, is formed. After a weft three-ply, etc., dryer canvas base is woven using this monofilament yarn as at least a part of warp and/or weft, web is piled on one face or both face of the base cloth, needle processed and become a uniform body to afford a paper making dryer canvas roll.

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 Conventionally, a dryer canvas used in a dry part of a paper machine usually uses fibers made of a synthetic resin such as polyethylene terephthalate (hereinafter referred to as PET) or polypropylene (hereinafter referred to as PP). Has been done.

Although PP has excellent resistance to moist heat and chemicals, it has a melting point of 160 ° C. and is poor in dry heat resistance, so that its place of use is limited.

Therefore, the dryer canvas is mainly composed of P
ET is used. However, although PET is excellent in dry heat resistance, it is inferior in alkali resistance and wet heat resistance, and there has been a problem that the life is shortened depending on use conditions.

On the other hand, the speed of paper machines has increased, the vapor pressure has been set to a high value, and a dryer canvas capable of withstanding high temperatures has been required.
There are some things that cannot be handled by P or PET.

For this reason, recently, a dryer canvas using fibers made of a heat-resistant synthetic resin such as polyether-ether ketone (hereinafter referred to as PEEK) or polyphenylene sulfide (hereinafter referred to as PPS) has been used. ing.

The price of PEEK or PPS is P
It was very expensive compared to ET, so the price of dryer canvas increased significantly, and there was a problem in terms of economy.

Therefore, the patent application publication No. 4-50024
In No. 7, as a polyester having a hindered carboxyl group, for example, [poly (1.4-cyclohexanedimethylene terephthalate)] (hereinafter referred to as PCTA),
It has also been proposed to use fibers having a higher hydrolyzability and a melting point higher than 260 ° C. to make a cloth for a paper machine.

However, PCTA is problematic as a general material because it has problems with the required characteristics of a dryer canvas used as a running belt, such as bending resistance and moderate strength retention.

On the other hand, paper manufacturers have a strong refusal to increase costs, and they cannot easily approve the price increase of dryer canvas.

On the other hand, since the monofilament has excellent characteristics in terms of antifouling property, it is indispensable to use the monofilament in this type of application.

Therefore, there is a need for a monofilament for papermaking dryer canvas which is stable under today's severe papermaking conditions, has low cost, and has excellent physical properties.

[0013]

The present invention has been achieved as a result of studying to solve the above-mentioned problems of the prior art.

Polyethylene terephthalate containing an unreacted carbodiimide compound and a thermoplastic polymer containing no fluorine atom has excellent steam resistance and is cheaper than PPS. Therefore, this resin is used. The monofilament (hereinafter referred to as NPM) was used for a dryer canvas.

As a result, it has been found that the above problems can be solved by using NPM in a dryer canvas.

If the dryer canvas is woven as it is, it greatly expands and contracts in the length and width directions due to heat, moisture or tension during use on a paper machine. Therefore, in order to prevent such dimensional changes during use, heat setting is performed. It is necessary to process and give dimensional stability.

Usually, this heat setting process is performed at a temperature of 1
The temperature is set to about 60 to 180 ° C., and the tension is usually set in the range of 1 kg / cm to 3 kg / cm depending on the tension when the dryer canvas is used.

When the dry heat shrinkage of NPM was measured, as shown in Table 1, it was found that almost all PET monofilaments (hereinafter referred to as TM
That. ) Has almost the same characteristics. On the other hand, PPS monofilaments show different properties.

[0019]

[Table 1]

Table 1 shows the dry heat shrinkage measured for monofilaments having the same diameter and a diameter of 0.46 mm.

This means that NPM exhibits almost the same behavior as TM when heat set processing is performed.

Therefore, it means that the specification of the dryer canvas when using TM can be replaced by NPM as it is.

If the dryer canvas has the same structure, yarn size, weaving density, etc., the finished product will have the same thickness, air permeability and the like as when TM is used.

Therefore, the TM canvas made of the paper machine using the TM dryer canvas can be replaced with the NPM dryer canvas.

Therefore, at the place where the use condition of the paper machine becomes severe, the structure of the monofilament used for the dryer canvas is changed from TM to NPM.
It is possible to obtain a dryer canvas of the same specifications with the yarn size and weaving density unchanged.

This also shows a great advantage of using NPM.

Depending on the intended use, it is possible to mix NPM and TM without using NPM for all warp or weft yarns, and to select NPM ratio of 25%, 50%, 75%, etc. as appropriate. is there.

A monofilament having the same diameter of 0.46 mm was subjected to a steam resistance test at 120 ° C. and 1.0 kg /
It was carried out in a saturated steam atmosphere of cm ² . Table 2 shows the results.

[0029]

[Table 2]

In Table 2, the vertical axis represents the strength retention (%),
The horizontal axis indicates the number of days to be treated (day), which represents the steam heat resistance.

As can be seen from Table 2, TM has 1 processing days.
The retention rate becomes 50 (%) on the 4th day, and the retention rate becomes 0 (%) on the 20th day.

It was found that NPM was as high as 80 (%) even after 21 days. Therefore, it can be seen that NPM has excellent steam resistance as compared with TM.

Therefore, it has been proved that NPM is a monofilament which is stable even under severe papermaking conditions, is low in cost and has excellent physical properties and is suitable for use in a dryer canvas.

[0034]

In order to solve the above-mentioned problems, the first invention is a papermaking dryer canvas.
Provided is a dryer canvas for papermaking, in which a monofilament made of polyethylene terephthalate containing a carbodiimide compound in an unreacted state and a thermoplastic polymer containing no fluorine atom is used for at least a part of warp and / or weft.

In the second invention, the monofilament used in the papermaking dryer canvas has a diameter of 0.1 to 2.0.
Provided is a papermaking dryer canvas using a thread having a circular cross section of mm.

In the third invention, the long side of the monofilament used in the papermaking dryer canvas is 0.3 to 1.3.
The present invention provides a dryer canvas for papermaking, which uses a yarn having a flat cross section in mm and a short side: long side ratio of 1: 1.4 to 1: 4.

A fourth invention provides a papermaking dryer canvas in which the above-mentioned papermaking dryer canvas is used as a base cloth and a needling is performed by laminating a web on one side or both sides of the base cloth.

[0038]

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

(Example 1) Diameters of 0.46 mm and 0.
An NPM with a circular cross section of 5 mm was created.

Using the above two types of monofilaments,
A weft double weave dryer canvas 1 having the specifications shown in FIG. 1 was woven.

As the warp yarn 2, NPM having the above-mentioned diameter of 0.46 mm
With a weaving density of 63.2 yarns / 2.54 cm, and using NPM with a diameter of 0.50 mm as the weft yarns 3 for the front and back layers. .5
Woven with 4 cm.

After weaving, heat setting was performed at a temperature of 160 ° C. and a tension of 1 kg / cm.

Dryer canvas 1 obtained as a result
Is as shown in Fig. 1, the thickness is 2.17mm, and the air permeability is 2
It was 8,300 cc / min. / Cm ² .

The above-mentioned air permeability is JIS L1005.
11. Water column using a measuring instrument conforming to the Frazier method.
The amount of air passing through a hole having a size of 7 mm and a measurement area of 10 cm ² in one minute is converted and displayed per unit area.

(Embodiment 2) As in Embodiment 1, the diameter is 0.
Circular cross section NPMs of 46 mm and 0.50 mm were made.

Using the above-mentioned two types of monofilaments, a weaving triple weave dryer canvas 1 having the specifications shown in FIG. 2 was woven.

As the warp yarn 2, NPM having the above diameter of 0.46 mm
With a weaving density of 63.5 yarns / 2.54 cm, using the NPM having a diameter of 0.50 mm as the weft yarns 3 for the front and back layers, and weaving 7 acrylic denier filaments of 200 denier as the weft yarn 4 for the middle layer. Weaving density of these wefts is 15.0 × 3 / 2.5
Woven with 4 cm.

After weaving, heat setting was performed at a temperature of 160 ° C. and a tension of 1 kg / cm.

Dryer canvas 1 obtained as a result
Is as shown in Fig. 2, the thickness is 2.18 mm, and the air permeability is 1
It was 5,370 cc / min. / Cm ² .

(Embodiment 3) As in Embodiment 1, the diameter is 0.
Circular cross section NPMs of 46 mm and 0.50 mm were made.

Using the above-mentioned two types of monofilaments, a weft double weave dryer canvas 1 having the specifications shown in FIG. 3 was woven.

Of the warp yarns 2, as shown in FIG. 3, when one repeat unit is 8 units, the warp yarns 2 among the 8 yarns are NPM having a diameter of 0.46 mm, and the warp yarns 2 have a diameter of 0. Using TM of 0.46 mm, weaving density 64.3 /
NPM having a diameter of 0.50 mm was used as the front and back wefts 3 having a diameter of 2.54 cm, and the wefts 3 were woven at a weaving density of 16.4 × 2 yarns / 2.54 mm.

After weaving, heat setting was performed at a temperature of 160 ° C. and a tension of 1 kg / cm.

The resulting dryer canvas has a thickness of 2.06 mm and an air permeability of 26,36 as shown in FIG.
It was 3 cc / min. / Cm ² .

In this embodiment, the warp yarns 2 are not all made of NPM,
NPM and TM are 50 (%) each, and depending on the application, N
This is to reduce the cost by making it possible to deal with the case where it is not always necessary to set the PM to 100 (%), placing importance on the cost aspect.

(Embodiment 4) In comparison with Embodiment 3, this embodiment shows a case in which only the design is a weft double weave, as shown in FIG.

As shown in FIG. 4, among the warp yarns 2, when one repeat unit of 8 is used, 4 of the 8 warp yarns 2 are made of NPM having a diameter of 0.46 mm. The warp 2 is made of TM having a diameter of 0.46 mm and the weave density is 6
NPM having a diameter of 0.50 mm was used as both front and back wefts 3 at 3.9 yarns / 2.54 cm, and the weaving density of these weft yarns 3 was 15.2 × 2 yarns / 2.54 cm. .

After weaving, heat setting was carried out at a temperature of 160 ° C. and a tension of 1 kg / cm. The resulting dryer canvas was as shown in FIG. 4, and had a thickness of 1.77 mm and an air permeability of 21,584 cc / min. / Cm ² .

In this embodiment, the warp yarns 2 are not all made of NPM,
NPM and TM are 50 (%) each, and depending on the application, N
By making it possible to deal with the case where it is not always necessary to set PM to 100 (%), the cost is emphasized and the cost is reduced.

(Embodiment 5) As in Embodiment 1, the diameter is 0.
Circular cross section NPMs of 46 mm and 0.50 mm were made.

Using the above two kinds of monofilaments, a weft double weave dryer canvas 1 having the specifications shown in FIG. 5 was woven.

Of the warp yarns 2, as shown in FIG. 5, when one repeat unit of eight is used, two warp yarns 2 out of eight
Is made of NPM having a diameter of 0.46 mm, 6 warps 2 are made of TM having a diameter of 0.46 mm, and the weaving density of these warps 2 is set to 63.9 yarns / 2.54 cm. As shown in 5, in the case of the unit of 8 threads, the two weft threads 3 of (4) and (8) are NP with a diameter of 0.50 mm.
Use M and other (1) (2) (3) (5) (6)
The six weft threads (7) used TM with a diameter of 0.50 mm,
These wefts 3 were woven with a weaving density of 16.8 × 2 yarns / 2.54 cm.

After weaving, heat setting was performed at a temperature of 160 ° C. and a tension of 1 kg / cm.

The resulting dryer canvas 1 has a thickness of 2.06 mm and an air permeability of 25, as shown in FIG.
It was 772 cc / min. / Cm ² .

In this embodiment, the warp 2 has an NPM of 25 (%).
The TM is 75 (%) and the weft is 25 NPM.
The TM is 75 (%) in (%), and the application is limited to the applications that can be sufficiently supported by this specification, and the cost is further reduced as compared with the case of the fourth embodiment.

Example 6 A circular cross section NPM having a diameter of 0.80 mm and a flat cross section NPM having a short side of 0.58 mm and a long side of 0.88 mm were prepared.

A weft double weave dryer canvas 1 having the specifications shown in FIG. 6 was woven using the above two kinds of monofilaments.

As the warp yarn 2, NPM having a flat cross section with a short side of 0.58 mm and a long side of 0.88 mm was used.
Weaving with a weft density of 12.6 × 2 yarns / 2.54 cm, using NPM having a diameter of 0.80 mm as both weft yarns 3 on the front and back layers at 9.6 yarns / 2.54 cm. did.

After weaving, temperature 160 ° C., tension 3 kg / cm → 1
The dryer canvas obtained as a result of heat setting at kg / cm is as shown in Fig. 6, the thickness is 2.81 mm, and the air permeability is 24,587 cc / min.
/ Cm ² .

In this embodiment, the warp 2 has a flat NP cross section.
Since M is used, it is particularly suitable for applications where surface smoothness is required.

Although the woven cloth was used as the dryer canvas in the embodiment, the woven cloth in this embodiment is used as the base cloth of the dryer canvas and the web is provided on one or both sides of the base cloth. It is also possible to stack them and then perform needling to obtain a paper dryer dryer canvas that is a needle canvas.

The shape and size of the NPM of the present invention may be appropriately selected depending on the application of the dryer canvas and the required conditions, but a circular shape having a diameter of 0.1 mm to 2.0 mm. Section or long side is 0.3
mm-1.3 mm, short side: long side ratio (1: 1.4)
A flat cross section in the range of (1: 4) is preferable.

That is, if the diameter of the circular cross section is less than 0.1 mm or the long side of the flat cross section is less than 0.3 mm, good spinning operation cannot be ensured depending on the spinning conditions. Also, the diameter of the circular cross section is 2.0 mm or more, or the long side of the flat cross section is 1.
If the thickness is 3 mm or more, sufficient quality cannot be secured during spinning. Therefore, the above-mentioned size range is preferable.

In the present embodiment, an example in which NPM and a polyester monofilament yarn are mixed has been described, but not limited to this example, it goes without saying that NPM and a yarn made of another material can be mixed.

Depending on the application, it is possible to replace a part of the main body of the dryer canvas using TM or the like with NPM and use it as a reinforcing thread, and it is also possible to reinforce only the ears with NPM. Is.

Further, the phrase "at least a part of the warp and / or the weft" described in claim 1 includes a case where a part of the main body or / and a part of the selvage is replaced or reinforced with NPM. Of course it is done.

[0077]

Industrial Applicability According to the present invention, it is possible to provide a dryer canvas for papermaking, which has excellent steam resistance and a long service life. Moreover, although the price is higher than PET, it is cheaper and more economical than PPS. There are advantages such as

Further, since it has the same dry heat shrinkage property as PET, the material of the yarn is not used when the usage conditions of the dryer canvas of the paper machine using the dryer canvas in which the material of the yarn is PET are strict. There is also an advantage that it is only necessary to replace it with a dryer canvas of the same specification that has been changed to NPM, and depending on the application, it is sufficient to mix TM without using NPM for all warp and weft threads. For such applications, NPM
There is also an advantage that the amount used can be reduced and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a specification diagram of a dryer canvas according to a first embodiment.

FIG. 2 is a specification diagram of a dryer canvas according to a second embodiment.

FIG. 3 is a specification diagram of a dryer canvas according to a third embodiment.

FIG. 4 is a specification diagram of a dryer canvas according to a fourth embodiment.

FIG. 5 is a specification diagram of a dryer canvas according to a fifth embodiment.

FIG. 6 is a specification diagram of a dryer canvas according to a sixth embodiment.

Claims (4)

[Claims] 1. In a papermaking dryer canvas, a monofilament composed of polyethylene terephthalate containing a carbodiimide compound in an unreacted state and a thermoplastic polymer containing no fluorine atom is used as at least a part of warp and / or weft and woven. A papermaking dryer canvas. 2. The monofilament according to claim 1,
A dryer canvas for papermaking, which has a circular cross section with a diameter of 0.1 to 2.0 mm. 3. The monofilament according to claim 1,
The long side is 0.3 to 1.3 mm, and the short side: long side ratio is 1: 1.
A dryer canvas for papermaking, which has a flat cross section in the range of 4 to 1: 4. 4. A papermaking dryer characterized in that the papermaking dryer canvas according to any one of claims 1 to 3 is used as a base fabric, and a needling is performed by laminating a web on one side or both sides of the base fabric. canvas.