JP2987395B2 - 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 As a papermaking dryer canvas, a plastic canvas made of a monofilament is frequently used from the viewpoint of drying and durability of wet paper. However, canvases woven with conventional synthetic fiber multifilaments are still widely used because of the quality of wet paper to be dried.

[0003] These multifilament canvases use a canvas which is appropriately woven using multifilament twisted yarns of synthetic fibers such as polyester, polyacryl, and nylon specially modified for papermaking. In addition, research on modification of these synthetic fibers to improve their performance has been continued.

On the other hand, new synthetic fibers have been developed with the progress of polymer chemistry, and fibers having properties such as heat resistance, chemical resistance, high strength, and high rigidity have been supplied to the market, and some of them have been used for dryer canvas. I have. For example, 780 in 1988
No. 98 discloses that a part of a dryer canvas using a monofilament yarn includes a polyether ketone (PEE).
K), a canvas in which heat-resistant synthetic resin monofilaments of polyphenylene sulfide (PPS) are interwoven for warp is disclosed. However, although such a new synthetic fiber is used as a monofilament, it is not generally used as a multifilament.

Japanese Utility Model Laid-Open Publication No. 2-57999 discloses a canvas in which multifilament yarns of para-based aromatic polyamide fibers are used for the warp and weft yarns. And "Technola" (trademark of Teijin Limited).

The use of multi-filament yarn of para-aromatic polyamide fiber certainly improves the heat resistance and the like, but the cost is high and the cost of the canvas increases.

As a problem of a canvas using a multifilament yarn, there is a problem of dimensional stability in addition to the above-mentioned heat resistance. A canvas using a multifilament yarn necessarily has insufficient rigidity and lacks dimensional stability. Therefore, after canvas weaving, the woven fabric is subjected to resin processing to increase rigidity and to provide dimensional stability.
Even the multifilament processed with the resin does not reach the dimensional stability of the monofilament.

An object of the present invention is to improve the heat resistance and dimensional stability, which are the weaknesses of the multifilament, while making use of the surface property of the soft touch, which is a feature of the multifilament, while improving economic efficiency.

[0009]

Means for Solving the Problems The inventors of the present invention have completed the present invention as a result of repeating experiments by trial and error to achieve the above object.

[0010] The present inventors first examined what kind of fiber has a sufficiently high strength and high rigidity as a material of a multifilament, together with its economic efficiency. Second
Next, attention was paid to the adhesiveness of the resin to the multifilament material fiber, and what kind of fiber had the best adhesiveness was examined.

In the first study, polyethylene naphthalate fiber is a promising candidate. This fiber is known from JP-B-56-27639 and JP-B-57-5915.
Known synthetic fiber that has been proposed for use as a canvas for papermaking, and has excellent wet heat resistance and hydrolysis resistance,
It is said that the service life of the canvas can be extended and the dimensional stability is improved.

[0012] Moreover, the polyethylene naphthalate multifilament yarn is slightly more expensive than the polyester multifilament yarn, but is less expensive than the aromatic polyamide multifilament yarn, and therefore has sufficient economic efficiency.

However, in practice, it has been found that a canvas using polyethylene naphthalate fiber still has room for improvement in terms of dimensional stability, and has not been practically manufactured at present. Therefore, when polyethylene naphthalate fiber was used for a canvas, it was examined how to provide sufficient shape stability.

First, the following test was conducted to confirm the basic performance of the polyethylene naphthalate multifilament yarn. As a sample, a polyethylene naphthalate multifilament yarn having a thickness of 1000 denier was used. As a comparative example, a polyester multifilament yarn having a thickness of 150 denier was used.
A denier of 0 was used.

(Steam Resistance Test) FIG. 1 shows the results of a steam resistance test performed in a saturated steam atmosphere at a pressure of 1.0 kg / cm ² . In the figure, the vertical axis represents the strength retention rate (%), and the horizontal axis represents the number of processing days (days). As can be seen, the polyester multifilament yarn is 13
On the day, the tenacity retention becomes 0, but the polyethylene naphthalate multifilament yarn is about 70% even on the 13th day.
It took three or more times as long as the polyester multifilament yarn until the tenacity retention became zero.

(Dry Heat Resistance Test) FIG. 2 shows the results of a dry heat resistance test performed in a dried state at 180 ° C. In the figure, the vertical axis represents the strength retention rate (%), and the horizontal axis represents the number of processing days (days). As can be seen from the figure, the polyethylene naphthalate multifilament yarn maintains about 1.7 times the tenacity retention of the polyester multifilament yarn at 30 days after the start of the test.

(Dry Heat Shrinkage Test) FIG. 3 shows the measurement results of the dry heat shrinkage. It can be seen that the polyethylene naphthalate multifilament yarn has a much lower shrinkage than the polyester multifilament yarn. This indicates that the polyethylene naphthalate multifilament yarn has excellent dimensional stability.

From the results of the above three tests, it can be seen that the polyethylene naphthalate multifilament yarn has remarkably excellent steam resistance and dry heat resistance as compared with the polyester multifilament yarn, and has low shrinkage.

Accordingly, polyethylene naphthalate multifilament yarn has dimensional stability even under severe papermaking conditions, is relatively inexpensive, has excellent physical properties, and is very suitable as a material fiber of a multifilament yarn suitable for a dryer canvas. Promising.

Next, as a second study, the adhesion of the resin was examined for polyethylene naphthalate multifilament yarn.

As test samples, two yarns of twisted polyethylene naphthalate multifilament yarn were prepared as follows.

Test sample 1 Twisted polyethylene naphthalate multifilament yarn 1000D / 1/4 Test sample 2 (Polyethylene naphthalate multifilament yarn 10
00D / 1 + Acrylic multifilament yarn 200D / 5) / 2 Conditions for resin processing

Each of these two samples was resin-processed by dipping a 17% strength solution of an epoxy emulsion resin, and then dried at 180 ° C. for 10 minutes.

The resin adhesion of the resin-processed test samples 1 and 2 was examined by the method shown in FIG. More specifically, the resin-processed test samples 1 and 2 are each separated by an interval L as shown in FIG.
= 70 mm, the middle part of the sample was pulled by a tensile tester, and the maximum bending load value at that time was measured. Load F
And the displacement Δl is as shown in FIG. It is considered that the greater the maximum bending load value, the greater the rigidity, and the rate of increase in rigidity is considered to be proportional to the resin adhesion.
The above test was conducted to examine how much rigidity the polyethylene naphthalate multifilament yarn can be expected by ordinary resin processing.

Next, as a comparative sample, the following twisted yarn conventionally used was subjected to substantially the same resin processing and subjected to the same rigidity test.

Comparative Sample (Acrylic Multifilament Yarn 200D / 2 + Polyester Multifilament Yarn 250D / 2 + Nylon Multifilament Yarn 210D / 2) / 4 Conditions for Resin Processing After resin processing by dipping a 17% strength solution of epoxy emulsion resin, Dry at 150 ° C. for 8 minutes.

FIG. 5 shows the results of the rigidity test. As can be seen from this figure, the maximum load F of the comparative sample is 2.6 g, but the maximum loads F of the test samples 1 and 2 are much lower than this. Since the value of the comparative sample was obtained as a result of subjecting the conventionally used multifilament material to conventional resin processing, this value can be said to be a value that is practically acceptable. Is clearly inferior in rigidity to the comparative sample, and it can be said that the resin adhesion is insufficient.

That is, it is understood that even if the polyethylene naphthalate multifilament yarn is twisted and woven as it is and conventional resin processing is performed, the rigidity required as a dryer canvas cannot be imparted.

Therefore, a method for improving the resin adhesion to the polyethylene naphthalate multifilament yarn was studied.

Even if resin processing is performed after the weaving of the woven fabric to improve the adhesiveness of the resin, the resin adheres to a part of the warp and the weft coming out of the surface of the woven fabric, but the resin extends to the inside of the woven fabric. And it is virtually impossible to completely adhere the resin to the entire surface of the warp and the weft. To infiltrate the resin into the woven fabric, for example, a method of infiltrating the resin by applying pressure to the woven fabric can be considered.However, a wide and long material such as a dryer canvas requires a huge pressure vessel, so the reality is Absent.

Therefore, it was studied to apply a primer treatment to the polyethylene naphthalate multifilament yarn to perform resin processing. Here, the primer treatment refers to a polyethylene naphthalate multifilament yarn before weaving.
In addition, it refers to attaching a resin or the like in advance in the state of the yarn before twisting , and thereby aims to greatly improve the adhesiveness of the resin when processing the resin after forming the fabric.

The following polyethylene naphthalate multifilament yarn was subjected to a primer treatment and twisted, and the yarn was subjected to the same resin processing as that applied to the test samples 1 and 2, and the maximum bending load value was measured.

Test Sample 3 Polyethylene naphthalate multifilament yarn (plastic
Immer treatment) 1000D / 1/4 Test sample 4 [Polyethylene naphthalate multifilament yarn (primer treatment) 1000D / 1 + acrylic multifilament yarn 200
D / 5] / 2

FIG. 6 shows the measurement results in this case. From the figure, the test sample 3 was 3.0 g and the test sample 4 was 4.3 g, which was higher than 2.6 g of the comparative sample, and it was confirmed that the adhesion of the resin was improved. .

In short, it has been found that if the polyethylene naphthalate multifilament yarn is subjected to a primer treatment, woven using the twisted yarn, and then subjected to resin processing, sufficient rigidity can be imparted as a dryer canvas.

The present invention has been completed as a result of the above considerations. The present invention relates to a dryer canvas constructed by using a polyethylene naphthalate multifilament yarn for at least a part of a warp and / or a weft. or before weaving the phthalate multi-filament yarn
It is obtained by weaving a base fabric of a dryer canvas by performing a primer treatment in the state of the yarn before twisting, and then performing a resin processing after weaving.

The present invention also relates to a dryer canvas in which a polyethylene naphthalate multifilament yarn is used for at least a part of a warp and / or a weft, and the polyethylene naphthalate multifilament yarn is subjected to a primer treatment in a yarn state. Is twisted with a multifilament yarn of another synthetic fiber, a base fabric of a dryer canvas is woven using the twisted yarn, and a resin process is performed after weaving.

In the present invention, such a papermaking dryer canvas is used as a base fabric, and a web is laminated on one or both sides of the base fabric, and then needling is performed, followed by resin processing.

[0039]

The polyethylene naphthalate multifilament yarn used in the present invention has a sufficiently high strength and high rigidity, and is subjected to a primer treatment at the yarn stage before twisting , so as to improve the adhesion of the resin after weaving. Compared to the preliminary resin processing step, the size of the primer processing equipment is small, and the entire surface of the yarn can be subjected to the primer processing. Function as an intermediary layer to help the resin adhere when
Sufficient resin adhesion is obtained, and the dimensional stability of the multifilament canvas is greatly improved in combination with the high strength and high rigidity.

[0040]

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

Example 1 As Example 1 of the present invention, a weaving double weaving dryer canvas 10 having the specifications shown in FIG. 7 was woven.

The dryer canvas 10 is obtained by twisting a warp 1 with one 800 denier polyethylene naphthalate multifilament yarn subjected to a primer treatment and one 250 denier T (polyester) multifilament yarn. Use thread. The weave density of the warp is 32.9 yarns / 2.54 cm. As the two weft yarns 2 of the surface layer and the back layer, one denier-treated polyethylene naphthalate multifilament yarn 500 denier, two T multifilament yarn 250 denier and N
(Nylon) A yarn obtained by twisting two multifilament yarns 210 deniers and further twisting four yarns. The weft weave density is 14.3 × 2 yarns / 2.54 cm.

In Example 1, a yarn obtained by twisting a polyethylene naphthalate multifilament yarn and a T multifilament yarn for the warp yarn 1 was used, but the T multifilament yarn is less expensive than the polyethylene naphthalate multifilament yarn. For that reason, it is not necessarily 100 (%)
When it is not necessary to use a polyethylene naphthalate multifilament yarn in the above, a T multifilament yarn can be mixed and used for cost reduction.

Further, the weft 2 is a yarn obtained by twisting a polyethylene naphthalate multifilament yarn, a T multifilament yarn and an N multifilament yarn, but the T multifilament yarn is used in the same manner as the warp 1 to reduce the cost. The reason for using the N multifilament yarn is to further improve the effect of resin processing after weaving since the N multifilament yarn has good adhesiveness to the resin.

After weaving, the dryer canvas 10 is heated to a temperature of 1 ° C.
85 ℃ → 175 ℃, tension 3kg / cm → 1kg / cm
KONISHING with a 40% strength solution of an emulsion resin of VONCOAT 3290 [trade name of self-crosslinkable acrylic ester copolymer dispersion of non-melamine resin low formalin type manufactured by Dainippon Ink and Chemicals, Inc.] For fabric processing.

The resulting dryer canvas 10
Was as shown in FIG. 7, the thickness was 2.49 mm, and the air permeability was 8,008 cc / min / cm ² .

The above air permeability is measured according to JIS L1005.
11. Water column using a measuring instrument conforming to the Frazier method.
The amount of air that has passed through a hole having a measurement area of 7 mm and a measurement area of 10 cm ² per minute is represented by conversion per unit area.

Example 2 As Example 2 of the present invention, a weaving double weaving dryer canvas 20 having the specifications shown in FIG. 8 was woven.

This embodiment is different from the first embodiment in that one of the four warps 21 is formed only on the weft yarn 22 on the paper contact side (PS), and the other one on the machine side (BS). ) Is used only for the warp 21 and the weft 22 because only the weft 22 is designed for the weft 22 on the paper side (PS) and the machine side (BS). The configuration of the yarn is the same as in the first embodiment.

One of the warps 21 is not exposed at all on the machine surface side (BS) of the dryer canvas 20, so that it is less likely to be worn and has an effect of extending the life of the dryer canvas 20.

After weaving, the dryer canvas 20 was subjected to resin processing in the same manner as in Example 1.

The resulting dryer canvas 20
As shown in FIG. 8, the thickness was 2.61 mm and the air permeability was 8,183 cc / min / cm ² .

In this embodiment, the case of a woven fabric as a dryer canvas has been described. However, the woven fabric of this embodiment is used as a base fabric of a dryer canvas, and a web is laminated on one or both sides of the base fabric. Thereafter, needling is performed to obtain a papermaking needle canvas or a papermaking dryer canvas.

In this embodiment, the example of the Boncoat 3290 is shown as the resin used in the resin processing. However, the resin is not limited to this, and it is a matter of course that other resins such as epoxy resin can be processed. The processing conditions are not limited to those of the embodiment, and other conditions can be appropriately used.

In the case of the primer treatment, an example in which an epoxy emulsion resin is used has been described. However, the invention is not limited to this, and a primer treatment with another resin is also possible. Of course, it can be used if it is.

In this embodiment, the example in which the polyethylene naphthalate multifilament yarn and the multifilament yarn of another material are twisted has been described, but the polyethylene naphthalate multifilament yarn can be used alone (100%). It is.

In some applications, for example, a part of the main body of a dryer canvas using polyester multifilament yarn or the like can be replaced with polyethylene naphthalate multifilament yarn as a reinforcing yarn. Reinforcement with naphthalate multifilament yarn is also possible.

Further, the phrase “at least a part of the warp and / or the weft” in claims 1 and 2 replaces a part of the canvas body and / or a part of the ear with a polyethylene naphthalate multifilament yarn. Or, the meaning includes the case of reinforcement.

[0059]

Industrial Applicability According to the present invention, it is excellent in steaming resistance, has dimensional stability even under severe papermaking conditions, and is most suitable for applications requiring a soft touch surface with high flexibility. A dryer canvas can be provided, and the price is slightly higher than that of polyester, but there are advantages such as being relatively inexpensive and having no economical problems as compared with PPS.

[Brief description of the drawings]

FIG. 1 shows the results of a steam resistance test.

FIG. 2 shows the results of a dry heat resistance test.

FIG. 3 is a graph showing the results of a dry heat shrinkage test.

FIG. 4 (A) is a front view of a rigidity testing device for resin-processed yarn, and FIG. 4 (B) is a load-displacement curve diagram.

FIG. 5 is a diagram showing a maximum bending load value.

FIG. 6 is a diagram showing a maximum bending load value.

FIG. 7 is a diagram showing a structure of a canvas according to the first embodiment of the present invention.

FIG. 8 is a view showing a structure of a canvas according to a second embodiment of the present invention.

[Explanation of symbols]

 1,21 warp yarn 2,22 weft yarn

Claims (3)

(57) [Claims] 1. A polyethylene naphthalate multifilament yarns warp and / or at least a portion configured with a a drier canvas of the weft, and before weaving the polyethylene naphthalate multifilament yarns
A dryer canvas for papermaking, characterized in that a base fabric of a dryer canvas is woven by performing a primer treatment in a state of the yarn before twisting, and then subjected to a resin processing after weaving. 2. A dryer canvas comprising a polyethylene naphthalate multifilament yarn for at least a part of a warp and / or a weft, wherein the polyethylene naphthalate multifilament yarn which has been subjected to a primer treatment in a yarn state is used as another yarn. A dryer canvas for papermaking, characterized by twisting with a multifilament yarn of synthetic fiber, weaving a base fabric of a dryer canvas using the twisted yarn, and processing the resin after the weaving. 3. A dryer canvas for papermaking, comprising laminating a web on one or both sides of a base fabric of the dryer canvas according to claim 1 and needling the web, followed by resin processing.