JPS6338477B2 - - Google Patents

Description

BACKGROUND OF THE INVENTION The field of the invention is the field of web materials, particularly fibrous webs formed in paper machines.
This invention relates to an endless press belt used in a mechanism for extracting water from web.

In the papermaking process, a web is formed by precipitating a fiber slurry onto a forming wire. During this process, a large amount of water flows out of the slurry. The new formed web goes to the press section. A series of press nips are arranged in the press section. The web eventually goes to a drying section. A heated drying drum is arranged in the drying section. In the drying section the web is reduced in water content to the desired amount.

From an energy cost perspective, it is desirable to remove as much water as possible from the web before entering the drying section. The drying drum of this section is often heated by steam, which increases cost if large amounts of water need to be removed.

It has been found to be advantageous to use extended press nips rather than nips formed by a pair of adjacent rollers. This is because a greater amount of water can be removed by increasing the time the web is under pressure in the nip.
These facts are recognized by those skilled in the art;
Several patents have been issued regarding this.
These patents include U.S. Patent Re.30268, 4201624,
4229253 and 4229254.

When using flared press nips to dewater a fibrous web, the web is sandwiched between two moisture-absorbing felts and a belt. The felt is wrapped around cylindrical press rolls with the web between them. Meanwhile, the belt is arranged to apply pressure to the felt and roll. The pressure show exerts pressure on the belt of the press section.

Certain problems arise when dewatering webs in enlarged nips. That is, it has been found that in the conventional press, a bulge occurs in the belt at the tip of the nip. This problem is related to the above US patent.
4229253 and 4229254, certain belt structures have been proposed to overcome this problem.

However, the belts that have been proposed so far are
It cannot be said that it is sufficiently good.

[Summary of the invention]

The present invention relates to an endless belt used in a fibrous web dewatering device. The fibrous web dewatering apparatus includes a flared press nip formed by a roll and a belt of the present invention. The belt is forced toward the roll by a pressure shoe, exerting pressure on the fibrous web and felt in the nip.

The endless belt for a fiber web dewatering press according to the present invention is composed of a base fabric and a synthetic resin impregnated material impregnated into the base fabric from one side thereof,
The impregnating material is comprised of a substantially 100% solid solid composition that is flexible and impermeable to liquids, with one surface comprising the base fabric and the other surface comprising the base fabric. It is composed of an impregnated material and is characterized by being uniform and smooth.

In the present invention, a two-layer monofilament fabric can be used as the basic fabric, and a fabric made of polyester can be used as the basic fabric.

The base fabric may have multiple layers other than two layers, or may have a single layer. However, when manufacturing the belt of the present invention by impregnating the base fabric with the impregnating material, the base fabric should have a roughness sufficient to allow the impregnating material to sufficiently penetrate and eliminate voids from the base fabric. select.

Furthermore, in the present invention, as an impregnating material, substantially
A 100% solid polyurethane resin can be used.

As the impregnating material, thermosetting synthetic resins other than polyurethane, polypropylene, and other thermoplastic synthetic resins can also be used.

The belt of the present invention as described above uses a basic fabric, a synthetic resin impregnated material is impregnated from one side of the basic fabric, and the impregnated material is flexible and prevents liquid from permeating. Based on the substantially 100% solid solid composition with impermeable impermeability, the following advantages exist:

(1) Can be made thinner than conventional belts. That is, the belt of the present invention has a diameter of, for example, 0.050 to
It can be made as thick as 0.150 inches and can be used satisfactorily. In contrast, conventional belts, for example, have a
inches thick. Therefore, the belt of the present invention is flexible, and together with the fact that the impregnated material permeates into the base fabric, it is extremely unlikely to break due to bending fatigue, and peeling between the base fabric and the impregnated material is extremely unlikely to occur. . Furthermore, since the belt of the present invention is thin, it does not bulge when pressure is applied between the pressure shoe and the roll at the nip, as would the case with the conventional thick belt.

(2) It can be lighter than conventional belts. For example, a belt of the present invention measuring 24'60" x 170" weighs about 200 pounds, while a conventional belt of comparable dimensions disclosed in the above-mentioned US patent weighs about 1200 pounds. As described above, since the belt of the present invention is sufficiently light, the load on the belt drive system of the paper making machine can be sufficiently reduced.

(3) It is easy to manufacture and can be obtained in any size.
In other words, conventional endless belts with an internal reinforcing structure have
It is shaped on a large mandrel and then vulcanized in a large autoclave. Therefore, it is difficult to obtain belts with very large dimensions. On the other hand, since the belt of the present invention uses a base fabric and only needs to be impregnated with the impregnating material from one side, the base fabric is sequentially penetrated and coated with the impregnating material along the length direction of the belt. Therefore, a belt of desired large size can be easily obtained.

(4) Good yield during manufacturing. That is, when a synthetic resin impregnating material containing a solvent or water is infiltrated into a basic fabric, defects such as pinholes are likely to occur after the impregnating material hardens, but when a substantially 100% solid composition is used, this The occurrence of such defects can be sufficiently prevented.

[Specific description of the invention]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The endless belt for dewatering presses for fiber webs according to the present invention will be specifically described below with reference to FIGS. 1 to 3.

1 and 2 are side sectional views showing an example of a widened press nip used in a belt according to the present invention, and FIG. 2 is a front partial sectional view thereof.

The nip is formed by a cylindrical press roll 12, a pressure shoe 14 and a belt 16.
The shoe 14 has an arched surface facing the press roll 12. The belt 16 is arranged so as to press against the surface of the press roll 12. The arched surface of the pressure shoe 14 has a radius approximately equal to the press roll 12. Press roll 12
and pressure shoe 14 can be adjusted by conventional hydraulic or mechanical devices (not shown). The device is connected to a rod 18 which is pivotally attached to the shoe 14. The rod 18 can also be adapted to apply a desired pressure to the shoe 14. In addition, pressure show 1 in Figures 1 and 2
4 and press roll 12 are the same as those used conventionally, and it goes without saying that the belt of the present invention can be used in devices other than this device.

FIG. 3 is a partial sectional view showing an example of a belt according to the present invention.

The belt 16 used as shown in FIGS. 1 and 2 is composed of a base fabric 20 and a synthetic resin impregnated material 22 that is impregnated into the base fabric from one side.

As the impregnating material 22, a thermosetting synthetic resin such as polyurethane can be used. Further, as the impregnating material 22, a thermoplastic synthetic resin such as polypropylene may be used. These synthetic resins are 100%
A solid solid material is used. Therefore, no air bubbles are generated during the curing process when manufacturing the belt of the present invention, and therefore no lubricant permeates or separation between the base fabric 20 and the impregnated material 22 occurs when the belt is used. .

The base fabric 20 has a roughness sufficient to allow the fluidized synthetic resin to penetrate throughout. If this penetration is insufficient, voids are formed within the belt, and during use, the lubricant used between the belt and the shoe 14 passes through the voids to the felt 2.
7 and also the disadvantage of contaminating the fiber web. In addition, the basic fabric 20 is made of material such that it has sufficient strength to be stable under the conditions of use in a paper making machine (i.e., stable in length and width, and good guiding performance and stability during running). and the thickness of the thread. Examples of threads that can be used include, but are not limited to, polyester monofilament.

As shown in FIG. 3, one surface 16' of belt 16 is comprised of impregnated material 22, which is sufficiently uniform and smooth. This surface is brought into contact with the pressure shoe 14 during use in a paper machine.

On the other hand, the other surface of the belt 16 includes a base fabric 20, as shown in FIG.
That is, this display has a structure in which a part of the basic fabric 20 protrudes from the impregnating material 22, and the degree of penetration of the impregnating material 22 into the basic fabric 20 is the third.
If it is shallower than the case shown in the figure, the impregnating material 22
may not be visible from this surface side, and it may appear that only the basic fabric 20 forms the surface. This surface is covered with felt 27 when used in a paper machine.
be brought into contact with

The belt according to the present invention as described above is manufactured in the following manner.

First, weave an endless fabric of the desired length,
The woven fabric can be used as it is as the basic woven fabric 20 of the present invention. Further, the endless fabric obtained by inserting fibers by needling can also be used as the basic fabric 20 of the present invention.
Furthermore, both ends of the non-endless fabric are joined by a conventional method to obtain the endless basic fabric 20 of the present invention.
You can also get

Next, the basic fabric 20 obtained as described above is impregnated with a fluidized synthetic resin impregnating material from one side so as to cover the surface. This impregnation can be carried out, for example, by applying a fluidized synthetic resin to a substantially uniform thickness using a doctor blade, or by softening the synthetic resin sheet by heating, etc., and then pressing it against the base fabric. .

Thereafter, the impregnating material is sufficiently cured over a sufficient period of time.

Incidentally, if desired, the surface 16' composed only of the impregnating material 22 may be polished with sand or a grinder.
The surface can be made more uniform and smooth.

As described above, the belt of the present invention having a highly uniform thickness can be obtained.

The belt 16 obtained as described above can be used in the apparatus shown in FIGS. 1 and 2, as described above.

That is, belt 16 is disposed between pressure shoe 14 and press roll 12, with its smooth surface 16' in contact with said shoe 14. A fiber web 24 subjected to dewatering is placed between the first and second felts 26, 27 and introduced into the press nip 10. The above belt 16
The surface comprising the base fabric 20 is in contact with the felt 27. The surface 16' of the belt 16 in contact with the shoe 14 is supplied with lubricant by a lubricating means 28 located at the tip of the nip.

The belt 16 of the present invention can be easily repaired if the surface 16' becomes damaged during use and becomes pitted or otherwise irregular. That is, for example, the damaged area is cleaned with a solvent, an appropriate amount of synthetic resin is applied using a doctor blade so that it has a uniform thickness with the surrounding area, and it is cured using a heat gun, and as needed. You can sand the surface with sand.

The belt of the present invention as described above can be made sufficiently thin. Even if it is thin, it has sufficient strength because it is sufficiently reinforced by the base fabric. Even if the belt is bent at the nip, the stress generated internally (especially the compressive force and tensile force generated on both surfaces) is extremely small compared to a thick belt, so the belt is flexible and will not break due to bending fatigue. It is extremely unlikely that the base fabric and the impregnated material will peel off. Additionally, because the belt is thin, it does not bulge when pressure is applied between the shoe and the roll at the nip, as would happen with conventional thicker belts.

Furthermore, the belt of the invention can be made sufficiently light. Even if it is light, it has sufficient strength because it is sufficiently reinforced by the base fabric. As described above, since the belt of the present invention is sufficiently light, the load on the belt drive system of the paper making machine can be sufficiently reduced.

Examples of manufacturing the belt of the present invention are shown below.

Example 1: Two layers of polyester monofilament fabric were woven into a planar shape, heat stabilized and joined at both ends using conventional bonding techniques to obtain an endless base fabric.

Next, a 100% solid polyurethane resin manufactured by DuPont (DuPont Adeplay L100 (trademark)) is infiltrated from the outer surface of the basic fabric to the inside.
The outer surface was coated with the resin. This coating step was carried out using a doctor blade to smooth the surface consisting only of the impregnated material. Thereafter, the impregnating material was cured by heating.

Through the above steps, a belt of the present invention was obtained.

In addition, when this belt is used, it is turned over and the surface including the base fabric is defined as the outer surface.

Example 2 Two layers of polyester monofilament fabric were woven in a planar shape, heat stabilized and joined at both ends using conventional bonding techniques to obtain an endless base fabric.

The base fabric was passed through a finishing machine that included a pair of rollers. One of the rollers was an oil heated cylinder and a uniform thickness 100% solid polyurethane sheet was placed on the inside surface of the base fabric and passed between the heated cylinder and the base fabric. The temperature of the heating cylinder is kept uniform, and the resin sheet is melted uniformly.The base fabric and resin sheet are passed around the heating cylinder and sufficiently heated and pressed together, so that the polyurethane becomes plastic and fluid, and the base fabric melts. penetrated into the void. A smooth impregnated material surface was thus obtained, which required no further finishing steps.

The side edges were then deburred and sealed so that it could be used in a paper making machine.

Through the above steps, a belt of the present invention was obtained.

Example 3: An endless base fabric consisting of two layers of polyester monofilament having sufficient roughness for penetration of a synthetic resin impregnating material and good stability in width and length was prepared.

A polypropylene film approximately 0.02 inches thick was impregnated into the base fabric in a manner similar to Example 2 above. The temperature of the heating cylinder was maintained constant enough to uniformly melt the resin film. The melting point of the base fabric (polyester) was higher than the impregnating material (polypropylene), so the heating process did not destabilize the base fabric.

The side edges were then deburred and sealed so that it could be used in a paper making machine.

Through the above steps, a belt of the present invention was obtained.

[Brief explanation of drawings]

1 and 2 are side sectional views showing an example of a widened press nip used in a belt according to the present invention, and FIG. 2 is a front partial sectional view thereof. FIG. 3 is a partial sectional view showing an example of a belt according to the present invention. 10: Nip, 12: Press roll, 14: Shoe, 16: Belt, 16': Belt surface, 1
8: Rod, 20: Basic fabric, 22: Impregnated material, 2
4: Fiber web, 26, 27: Felt, 28:
Lubrication means.

Claims (1)

[Claims] 1. Consisting of a base fabric and a synthetic resin impregnated material impregnated into the base fabric from one side, the impregnated material is a substantially 100% impermeable material that is flexible and does not allow liquid to pass through. % solids, one surface is composed of the above-mentioned base fabric, and the other surface is composed of the above-mentioned impregnating material and is uniform and smooth, for use in a fibrous web dewatering press. Endless belt. 2. The endless belt for a fiber web dewatering press according to claim 1, wherein the base fabric is a two-layer monofilament fabric. 3. The endless belt for a fiber web dewatering press according to claim 1 or 2, wherein the impregnating material is substantially 100% solid polyurethane resin. 4. The endless belt for a fiber web dewatering press according to any one of claims 1 to 3, wherein the basic fabric is made of polyester.