JPS61258715A - Belt for manufacturing paper with smooth inner surface and manufacture thereof - Google Patents

Abstract

A belt (16) is disclosed having a base fabric (34) which has been impregnated by or immersed into a polymer material (36) so that it has a smooth inner surface (16'). The belt (16) is used to form an extended press nip (10) for dewatering a paper web (24). The press nip (10) is formed by forcing a stationary shoe (14) against the inner surface of the belt (16). The belt (16) is preferably made by mounting a base fabric (34) on the inner mandrel (40) of a cylindrical mold (38) and injecting an appropriate material in the mold. After the material is properly dispersed through the base fabric, it is cured.

Description

DETAILED DESCRIPTION OF THE INVENTION BACKGROUND OF THE INVENTION The present invention relates to an impermeable belt having a smooth inner surface;
More specifically, wide press lags are used to dewater the fibrous web formed in the paper machine.
d Prtas nip).

During the paper manufacturing process described in the prior art, a web is formed by depositing a fiber slurry onto a forming wire. During this process, a large amount of water is drained from the slurry, after which the newly formed web advances to the press section.

The press section includes a series of press nips. Finally the web advances to a drying section containing a heated dryer drum,
Here the water content is reduced to the desired level.

In view of the high cost of energy, it is desirable to remove as much water as possible from the web before it enters the drying section. The dryer drum in this drying section is sometimes heated by steam and can be quite costly if large amounts of water need to be removed.

It has been found that the use of wide press nips is also advantageous over the use of nips formed by pairs of adjacent rolls. By increasing the time period, the cilanib is subjected to pressure within the elag, allowing more water to be removed. This fact is recognized by those skilled in the art and several patents have been published. These patents are No. 30,268, No. 4,20
No. 1,624, No. 4.229,253 and No. 4,22
Including No. 9,254.

When using a wide press nip to dewater a fibrous web, the web is typically sandwiched between two moisture absorbent felts and a belt.

The felt is directed around a cylindrical press roll with a web therebetween, while a belt is positioned to apply pressure to the felt and the roll.

The pressure shoe applies pressure to the belt in the press location.

The belt has a very smooth surface in contact with the shoe, so that the belt can transfer pressure to the felt and fibrous web without overheating or abrasion.

Additionally, it must be impermeable to oils used to smooth the passage of the belt over the shoes and which can contaminate the felt and web. Conventionally,
The belt was made by applying a polymeric coating to the outer surface of an endless fabric. Since the belt is placed so that its inner surface is the surface in contact with the shoe, the endless covering fabric does the opposite (
(i.e. the inside becomes the outside). Although this operation is satisfactory for belts having a length of 24 feet or more, it has been found difficult to invert belts having a length of less than 24 feet. Furthermore, it has been found difficult to apply a coating to the outer surface of shorter belts.

It is an object of the present invention to provide a relatively short belt with a smooth inner surface suitable for use in wide press nips.

Another object of the invention is to provide a belt that is impermeable to oil.

Still another object of the present invention is to provide a method for manufacturing the above belt.

Other objects and advantages of the invention will become apparent from the following description of the invention. In accordance with the present invention, the belt is constructed from an endless base fabric embedded in a polymeric material formed with a smooth, frictionless inner surface. The above belt is prepared by preparing a mandrel with a smooth outer surface,
It is manufactured by placing an endless base fabric on the mandrel covered with a shell and then impregnating the base fabric with a polymer. As the polymer solidifies, the outer surface of the mandrel forms a smooth inner polymer surface.

DETAILED DESCRIPTION OF THE INVENTION A wide press nip is provided in accordance with the present invention for dewatering moving web material. Nip 10 is formed by a cylindrical press roll 12, a pressure seam 14 having an arcuate surface facing the press roll, and a belt 16 arranged to press against the surface of the press roll. The arcuate surface of the pressure seam has approximately the same radius of curvature as the press roll. Press roll and pressure seam
The distance between the normal hydraulic equipment connected to the rod 18 pivoted to the shoe 14! or may be adjusted by a mechanical device (not shown). The rod may also be driven to apply a desired pressure to the shoe. It will be appreciated that the pressure seams and press rolls described above and shown in FIGS. 1 and 2 are conventional, and other equipment is known in the art.

The paper web 24 is carried into the nip by the first felt 26 and away from the nip. The second felt 28 is used to absorb water extruded from the web 24 in the nip.

The lubricating means 30 applies a lubricant such as oil to the inner surface 1 of the belt 16.
6' to further reduce the friction between the inner surface and the shoe 14. The belt is entrained by rolls 32 which are used to guide the belt into the predetermined path shown.

The belt used in accordance with the invention is shown in detail in FIG. The belt has been found to be superior to belts currently known in the art, both from an operational standpoint and from manufacturing considerations. The belt 16 is made of polymeric material 3
The base material 7 is impregnated with an adhesive 34. Thermosetting resins such as polyurethane have been found to be suitable impregnating materials. Preferably a 100% polyurethane resin should be used to avoid oil formation during curing of the belt construction. Thermoplastic polymers such as polypropylene are also acceptable.

The base fabric 34 is sufficiently open to allow all impregnation. This eliminates the possibility of voids forming during the final seven apps. hmm? If there is a lubricant used between the belt and the shoe, it will pass through the belt and contaminate the υ felt and fibrous web. The fabric is endless and of uniform thickness in the final structure. The fabric also needs to be made to have sufficient stability under paper machine conditions. In other words, the belt must have length stability, width stability, and guiding properties.

The base fabric may consist of a single layer or multiple layers of one flat woven fabric that is heat stabilized and bonded using conventional bonding techniques. The base fabric can be made from polyester or other bulk material having the properties necessary for the present invention. The substrate may also be made endless (by endless weaving).

At least one side or surface of the belt, such as side 16/, is smooth for contacting pressure shoe 14.

Belts made in accordance with the present invention have been found to have many desirable properties. These belts can easily move over the pressure shoes and transmit pressure from the shoes to the web and press rolls.

Sufficient flexibility was obtained and the belt was found to be unaffected by the lubricant applied before entering the press nip.

The belt is manufactured in a cylindrical mold 38 (FIG. 4) having a shell 39 and concentric mandrels.

The mandrel has a smooth outer surface 40.

The spacing between the outer shell 39 of the mold and the inner mandrel determines the thickness or thickness of the belt. First, base material fabric 3
2 onto a smooth mandrel surface 40, then mold 3
8 is hermetically sealed with a cover 44. Next, the pressure inside the mold is
The air contained within the mold is substantially removed via a pipe 46 connected to a vacuum source (not shown). After the pressure in the mold is reduced, the appropriate polymer is injected into the mold through the /4' ear 48. Due to the low pressure within the mold, the polymer quickly fills the mold, including the gaps in the fabric. Advantageously, a smooth internal polymeric surface is formed along the mandrel surface 40. The polymer is crosslinked by applying heat to the mold. After the polymer has cured, the finished belt can be removed from the mold.

Alternatively, a self-crosslinking polymer catalyst mixture may be used as long as several hours are acceptable.

The resulting belt is shown in FIG. 3, with the fabric 34 being fully impregnated and impermeable to p-oils and other substances. The belt has a uniform caliper as a result of the forming operation.

Many variations of the invention can be made without departing from the scope of the invention as defined in the claims.

[Brief explanation of the drawing]

FIG. 1 is a side view of a wide press nip using a belt constructed in accordance with the present invention. 2 is a partial front view of the press two shown in FIG. 1; FIG. FIG. 3 is a side view of the belt used in the present invention. FIG. 4 is a partial side view of equipment used to manufacture belts constructed in accordance with the present invention. 14: Shoe, 18: Rod, 12: Press roll, 1
6: belt, 24: paper web, 26; first fuel), 2
8: second felt, 34: fabric base material. FIG.1

Claims (1)

Claims: 1. An endless belt for a wide press nip for paper production, comprising an endless substrate and an impregnating material that penetrates the fabric to form a smooth inner surface thereon. 2. The endless belt according to claim 1, wherein the base material is made of woven fabric. 3. The endless belt according to claim 1, wherein the substance is a polymer. 4. An endless belt according to claim 3, wherein said material is continuously applied to said substrate to render said belt impermeable. 5. An endless belt according to claim 4, wherein the material is applied by placing the substrate on a mandrel having a smooth outer surface and adhering the material to the mandrel and the substrate. 6. Prepare a cylindrical mold having a smooth mandrel and an outer shell, place an endless base material on the mandrel within the mold,
A method for producing an endless belt with a smooth inner surface, comprising subsequently injecting an impregnating substance into the mold. 7. The manufacturing method according to claim 6, wherein the mold is evacuated before injection of the substance to allow the substance to penetrate into the substrate. 8. The preparation of claim 7, wherein the material is a polymer, the substrate is a woven fabric, and further comprising heating the mold to cross-link the material to the substrate. Law.