JPH0229795B2 - SUKIGAMIKOTEINIOKERUEKUSUTENDETSUDONITSUPUPURESUYOENDORESUBERUTO - Google Patents

Description

[Detailed description of the invention] (a) Industrial application field This invention relates to an endless belt,
In particular, the present invention relates to an endless belt useful as a belt for an extended nip press (ENP) in a press part of a papermaking process.

(B) Prior Art In the press part of the papermaking process, there are roll presses and ENP as press methods, and ENP has become popular in recent years because it has various advantages.

To put it simply, ENP is a wet paper sandwiched between two sheets of felt. One side of the paper is held down with a rotating roll, and the other side is pressurized with a pressure shoe via an ENP belt to dehydrate it. This is a press to do.

As a belt for this ENP, it has been used since the 1980s.
As disclosed in Japanese Patent Publication No. 56596 and Japanese Patent Publication No. 57-56597, belts with a structure in which a fiber-reinforced structure is covered and buried with an elastic material are used, but when using such a belt, There was a problem in that the belt itself had an insufficient squeezing effect on the water squeezed out of the felt.

For this purpose, a belt is used in which a flat base fabric made of multi-woven synthetic fibers is woven into an endless shape, and an elastic material layer is formed on one side of the belt, so that the exposed surface of the base fabric contacts the felt. It is also practiced to improve the water squeezing effect based on the water absorption effect of the exposed surface of the base fabric. However, when such an ENP belt with exposed base fabric on one side is used, a water squeezing effect can be expected due to the water absorption action of the exposed surface of the base fabric at the time of initial use, but wear and tear on the exposed surface of the base fabric over time can be expected. There is a problem that the water squeezing effect decreases due to the collapse of the fiber structure, and in addition, this wear reduces the lifespan of the belt itself, resulting in the inconvenience that it can only be used in actual use for about 1 to 2 months. Ta.

(c) Purpose This invention was made in view of the above-mentioned conventional problems, and provides an extended belt in the press part of the papermaking process that has an excellent water squeezing effect without impairing the life or function of the belt itself. The purpose of this invention is to provide an endless belt for presses.

(D) Structure According to the present invention, an elastic material layer is integrally formed inside and on one side of a woven base fabric, and a hard or semi-hard sponge layer is formed on the other side of the base fabric. There is provided an endless belt for an extended nip press in a paper making process, which is characterized by being integrally formed.

As the base fabric used in this invention, conventional
Belts for ENP or equivalent belts can be used, such as 6-nylon, 6,6-nylon, 6,10-nylon, 12-nylon, etc.
Examples include base fabrics woven from monofilaments or multifilaments of nylon, aromatic polyamide, polyester, etc., and may be either plain-woven or multi-woven.

The elastic materials constituting the elastic material layer formed and integrated inside and on one side of the base fabric include polyurethane elastomers, acrylonidol-butadiene elastomers, ethylene-acrylic acid copolymer elastomers, and polyfluorocarbon-based elastomers known in the art. elastomer, epichlorohydrin rubber,
Examples include polyester elastomer, soft vinyl chloride, thermoplastic urethane, etc., and it is preferable to use polyurethane elastomer.

The most distinctive feature of this invention is that a hard or semi-hard sponge layer is formed and integrated on the other surface of the base fabric layer in order to be suitable as a layer constituting the felt contact surface of the ENP. “Hard or semi-hard” as used here refers to hard and semi-hard as defined by the so-called Ashida method [“Current status and issues in industrial applications of urethane foam” Plastic Materials, VoL9, No. 2, 32-36 (1968)]. means hard. Specific examples of these materials include rubbers such as nitrile-butadiene rubber and polyurethane elastomer;
Examples include synthetic resins such as soft vinyl chloride, polystyrene, and polyethylene, and other materials equivalent to these may also be used. Normally, JIS hardness is 90°~
Preferably, the angle is in the range of 99°.

As the sponge layer, a foam manufactured by an elution method or a foaming method is usually applicable. A typical elution method involves mixing the resin or elastomer in a molten state with a water-soluble salt (e.g., sodium chloride) powder and casting the mixture, and after cooling, the cast product is held in an aqueous medium and dispersed. An example of this method is to form a sponge by dissolving the water-soluble salt contained therein and forming pores. On the other hand, the foaming method is usually a method for producing plastic foam, such as containing or kneading a decomposable blowing agent, a volatile blowing agent, a reactive blowing agent, etc., and then heating it at normal pressure or under increased pressure. A method of foaming and forming a sponge can be applied.

It is preferable that the pores of these sponge layers are basically composed of open cells in view of water squeezing ability and the like. Of course, it may also partially contain closed cells. Since the sponge obtained by the elution method itself is composed of pores consisting mainly of open cells, it can be directly applied as the sponge layer of the present invention. On the other hand, sponges obtained by the foaming method usually consist of closed cells, so it is necessary to mix short fibers into the rubber or resin material before foaming and then foam them to create open cells. Can be done. At this time, open cells are formed around the mixed short fibers, making it possible to form the intended open cells. As short fibers used in this case, natural fibers such as cotton and linen, and synthetic fibers such as polyamide and polyester are suitably used, and the fiber length is suitably about 3 to 10 mm.

It is not preferable to make the porosity of the sponge layer too large in terms of its own strength, and it is 10 to 25.
%.

The endless belt of the present invention is usually obtained by forming an elastic material layer inside and on one side of a base fabric, and then forming a hard or semi-hard sponge layer on the other side.

To form the elastic material layer, apply an elastic material stock solution (usually 5,000 CP or less, preferably 1,500 to 1,500 CP) on one side of the base fabric.
2000CP) and curing at room temperature or under heating for a predetermined period of time. Alternatively, a sheet-like uncured elastic material may be laminated with a base fabric, and these may be heated and pressed using a press to be post-cured.

On the other hand, the hard or semi-hard sponge layer is formed by bonding and integrating a previously prepared sponge layer with an adhesive on the opposite side of the elastic material layer. Alternatively, it can be obtained by coating the surface with a resin or elastomer raw material containing a foaming agent or elution salts, and directly forming and integrating the resin or elastomer raw material according to the foaming method or elution method described above.

The belt of the present invention thus obtained can be put into practical use after being appropriately trimmed. At this time, it is also possible to further improve water squeezing efficiency by forming grooves and/or blind holes that do not reach the base fabric layer on the sponge layer forming surface, as shown in FIGS. 3, 4, and 5.

(e) Examples This invention will be explained in detail below with reference to Examples.

FIG. 1 is a perspective view showing an embodiment of the endless belt 1 of the present invention, and FIG.
It is an A′ cross-sectional view. In the figure, the endless belt 1 has a sponge layer forming surface 2 and an elastic material layer smooth surface 3, the length in the endless direction α is 7.62 m, and the width in the direction β intersecting the endless direction is:
It is 4.76m.

Such an endless belt 1 comprises a nylon base fabric layer 4 woven into a double weave, on one side of which an elastic material layer 6 made of a polyurethane elastomer has a smooth surface, and on the other side a hard layer 6 of a urethane adhesive layer 7. It is formed by integrally forming a sponge layer 5 and is provided with open cells 51 from the surface to the inside.

The nylon base fabric layer 4 is made of a double-woven fabric made of nylon filaments 41 and 42 with a diameter of about 0.4 mm, and its thickness is about 1.2 mm. Furthermore, the thickness a of the sponge layer 5 is about 3 mm, and the elastic material The thickness b of layer 6 is approximately 1 mm, and the total thickness of the belt is approximately 5.2 mm.
It is said that

The sponge layer is obtained by mixing nitrile rubber compound sulfur, cotton with a fiber length of 5 mm, and a DPT foaming agent and vulcanizing the mixture, and has a porosity of 15%.

Usually, the thickness of the base fabric layer 4 can be varied between about 0.7 to 2.0 mm, and the thickness of the hard sponge layer 5 can be varied between about 1.5 to 6.0 mm,
Furthermore, the thickness of the other elastic material layer 6 is approximately 0.5 to 2.0 mm.
It can be varied between.

In such an endless belt 1, the smooth surface 3 of the elastic material layer is brought into sliding contact with the pressure shoe, and the other sponge layer forming surface 2 is brought into contact with the felt. At this time, as the belt 1 is driven, moisture squeezed out of the felt by the pressing force of a press roll (not shown) is guided into the open cells 51, and then discharged to the outside by centrifugal force as the belt 1 rotates.

As described above, since the endless belt of the present invention has the hard sponge layer 5 formed on its surface, the water squeezing effect from the felt that is in contact with it is different from that of the conventional base fabric embedded type belt and the base fabric embedded type belt. Significant improvement compared to belts with one side of cloth exposed. Moreover, since the sponge layer 5 is hard or semi-hard, its surface hardly wears out due to changes over time, and therefore the original excellent water squeezing effect is maintained.

For this reason, conventional endless belts with one side of the base fabric exposed had a lifespan of about 1 to 2 months.
With this belt, it can be extended for about 3 to 4 months. Further, in this belt, the amount of water squeezed can be controlled by arbitrarily setting the porosity and thickness of the sponge layer within the above-mentioned ranges.

(f) Effects As described above, the endless belt of the present invention has excellent water squeezing effect and durability, and particularly contributes greatly to improving productivity in ENP.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing an embodiment of the endless belt of the present invention, Fig. 2 is a partial sectional view taken along the line A-A' in Fig. 1, and Figs. It is a partial plan view which shows another Example. DESCRIPTION OF SYMBOLS 1... Endless belt, 2... Sponge layer forming surface, 3... Elastic material layer smooth surface, 4... Nylon base fabric layer, 5... Hard sponge layer, 6... Elastic material layer, 7... Adhesive layer.

Claims (1)

[Claims] 1. An elastic material layer is integrally formed inside and on one side of a woven base fabric, and a hard or semi-hard sponge layer is integrally formed on the other side of the base fabric. An endless belt for extended nip press in the paper making process, characterized by: 2. The endless belt according to claim 1, wherein the sponge layer is made of sponge mainly having open cells. 3. The endless belt according to claim 1, wherein the sponge layer is made of open-celled sponge by mixing short fibers. 4. The endless belt according to claim 2 or 3, wherein the porosity of the sponge layer is adjusted to 10 to 25%.