JPS6037234B2 - Synthetic fiber papermaking net that prevents curling - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to papermaking silk, and in particular aims to prevent the occurrence of selvage curl by polishing the back side of both selvages of papermaking silk woven with synthetic fiber monofilament. ,
It is characterized by the thickness of both ear parts being thinner than the thickness of the central part.

In recent years, synthetic polymer monofilaments such as polyesteramide have been increasingly used as silk for papermaking, instead of metal mesh such as phosphor bronze and stainless steel, but the length (circumference) of this papermaking mesh The short one is 5 meters long, the long one is 7 meters long, and the middle one is endless with a length of 100 meters to 900 centimeters.

This net often becomes unusable due to abrasion, dirt, scratches, chicks, etc. In particular, curling, which is the lifting of both sides of the silk from the middle to the end of the use of the net, can also be a cause of this. . As schematically shown in FIG. 1, papermaking silk 1 is supported in an endless manner between a prestrol roll 2 and a couch roll 3, and carries pulp slurry 5 extruded from a stock inlet 4 and circulates therethrough.

During this time, the pulp slurry 1 is dehydrated by a suction box 6 or the like, but both ears 7 of the papermaking silk are located between the prestrol 2 and the couch roll 3 in the section where the pulp slurry 5 is on the silk, as shown in FIG. It rises by the height h shown in , and after being reversed by the couch roll 3, it hangs down. Such a curling phenomenon begins to occur as early as a few days after the silk is loaded into the paper machine, and the degree of curling becomes more severe as the silk approaches the middle and final stages of use. When the ear curls become severe, the wire guard malfunctions, the running of the net is not controlled, and the chicks are caught in the silk due to the net being lopsided, causing poor formation of the paper that is being made and making it difficult to use as paper. It will also reduce the value of The reason for this is that papermaking silk comes into contact with a number of stationary or rotating dewatering members such as suction boxes during use, and these dewatering members are made of metal, plastic, ceramic, or other materials that are harder than the mesh material. This is because, as it is used, silk undergoes abrasion and reduces its thickness. As is clear from the graph of the change in the thickness of the screen over time shown in FIG. 3, the screen for papermaking shows rapid changes in the initial stage of use, and thereafter changes are slow. The reason is thought to be as follows. Normally, in order to maintain dimensional stability in the length direction, nets are often made with a weave structure in which the warp threads are less likely to be worn out, and in this case, the weft threads are often exposed on the outermost surface of the back side of the silk. .

Both the ridge and weft have curvature, but the warp and weft yarns have much less curvature than the stripe direction yarns. In a net with this type of structure, the weft yarns exposed on the back side are the first to wear out, and in the initial stage of use, the area in which the weft yarns come into contact with the dewatering section is small, so the load per unit area is large and the thickness decreases. However, as wear progresses, the weft comes into contact with the dewatering member at its surface (wearing surface), and the load per unit area becomes smaller, so the thickness decreases gradually. Also,
As the overall yarn wear progresses, it loses its elasticity, and the weft yarn, which has a lot of bends, partially decreases in thickness due to wear and becomes more bendable, making it impossible to maintain the tension in the warp direction that was maintained before wear. The striped yarns exhibit a tendency to increase bending and the warp yarns to stretch linearly, resulting in a decrease in warp tension.
However, this kind of wear occurs mostly in the part where the pulp slurry 5 is placed, and since the load in the vertical direction of both ears 7 is small during net running, the wear in this part is caused by the pulp slurry being placed on the both ears 7. Less compared to the parts.

Therefore, in this both-ear portion 7, the change in the network structure as described above is relatively small, and the decrease in tension in the bonito direction is also small. Therefore, there is a difference in the warp tension between the portion where the pulp slurry is applied and abrasion occurs and the portion where both ears 7 are worn. . Since the warp tension is higher at both heel portions 7 than at the portion on which the pulp slurry 5 is placed, both heel portions 7 are lifted up in a twitching manner, causing selvage curl. The purpose of the present invention is to prevent the ear curl that occurs as described above, and a specific example thereof will be explained below.

Figure 4 shows the papermaking net of the present invention! Fig. 3 schematically shows a mid-direction cross section of the first embodiment.

The thickness of the silk for paper making of the present invention is reduced by polishing the back surfaces of both ear portions 7. It is desirable that the amount is about 15%. The range is the part where the pulp slurry 5 does not get on during paper making, and varies depending on the type of paper making, but it is 20 to 100 minutes from the edge.
Inside the skin. As shown in FIG. 3, the part of the papermaking net on which the pulp slurry is applied is worn out by use, and the amount decreases by about 30% at the end of use. Therefore, as mentioned above, the thickness of both ears, which are less prone to wear, is reduced by polishing, and the difference in shape between the central part of silk and both ears at the end of the silk's use is alleviated. Curling can be prevented. The example shown in Figure 5 is tapered so that the degree of polishing gradually decreases from the silk selvage to the center, reducing the thickness at the extreme end by 15 to 30%. is desirable.

For example, in order to obtain an ear part of this type, 100 to 20
He is known for polishing both ears with sandpaper as small as a flea.

Depending on the combination of the thickness of the monofilament used for the warp and weft and the binding structure, the amount of polishing on the surface of both ears 7 can be adjusted from 10 to 3.
Selecting 0% is effective in preventing the occurrence of ear curl. The width of both edges to be polished varies depending on the individual mechanical conditions of the paper machine and the paper width, but generally it is appropriate to polish a width of 20 to 100 ribs. As shown in the enlarged part of Fig. 6, the condition of the thread in the polished part is that the part 9 protruding from the back side of the twill thread 8 is mainly shaved off and its thickness is reduced, but the warp thread 10 and the silk thread are Depending on the combination of threads 8 or how the weave is constructed, the portions 11 of the warp threads 10 exposed on the back surface may also be slightly shaved. In the papermaking silk of the present invention, even if selvage curl occurs, the amount h of selvage curl is small, and there is no trouble in use due to selvage curl.

It is desirable to use polyester monofilament with low elongation as the warp of the synthetic fiber papermaking net of the present invention.

It is desirable to use synthetic fibers with high abrasion resistance, such as polyester monofilament or polyamide monofilament, for the striped yarn. Example warp polyester monofilament diameter 0.25 side striped polyamide monofilament diameter 0.3&ross;
Silk for papermaking with a net thickness of 0.63 is woven and heat-set to have 23 warps/arc and 15 threads/arc on the machine. At paper mill A, curls are noticeable from around the 20th day of use. At the beginning, around the 30th day, the height of the ear curl reached 3 m, and there were problems with poor handling of the running guide, poor formation near both ears, and paper thickness unevenness.

For this reason, on the 40th day, the silk's ear curls reached a height of 40 willows, and the trouble became so severe that it became unusable and was usually removed. At this factory, the same synthetic fiber monofilament silk as above was polished on the back side of both bridges in a width of 3 sq.m. to a vertical thickness of 0.55 ribs (amount of polishing: 12.
6%).

This net was used for 65 days and no ear curls occurred. According to the present invention, the number of days of use of synthetic fiber silk for paper making has been significantly improved.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a wire part of a paper machine, and FIG. 2 is a sectional view taken along line A-A' in FIG. 1, showing the state of the edge curl. FIG. 3 is a graph showing an example of the relationship between the rate of decrease in the thickness of the net and the number of days of use; FIG. 4 is a schematic cross-sectional view showing the polished state of the edge of silk for synthetic fiber papermaking according to the present invention; FIG. 5 is a schematic sectional view of another embodiment, and FIG. 6 is an enlarged sectional view showing the polished state of the silk selvedge according to the present invention. 1・
... Paper making net, 2... Prestrol, 3... Couch roll, 4... Stock inlet, 5... /f lupus slurry, 6... Suction box, 7... Ear part, 8.・
- Weft, 9, 11... protruding part, 10... warp. Figure 1 Figure 2 Figure 3 Figure 5 Figure 6

Claims (1)

[Claims] 1. By polishing the back side of both ears of a papermaking net woven from synthetic fiber monofilament, the thickness of both ears is made thinner than the thickness of the central part. A synthetic fiber papermaking net that prevents curling. 2. A papermaking net made of synthetic fibers that prevents edge curling according to claim 1, wherein the back surfaces of both edge portions are polished to a uniform thickness that is thinner than the center portion. 3. For paper making made from synthetic fibers that prevents edge curl according to claim 1, wherein the back surfaces of both edges are polished so that the edges are the thinnest and the thickness gradually increases as it approaches the center. network.