JP3080640B2 - Pressure belt for wide nip press - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure belt for a wide nip press, which has an improved water squeezing effect from wet paper in a press section of a paper machine.

[Conventional technology]

Generally, this type of wide nip press has a shoe 32 having a curved surface in surface contact with the lower surface of a roll 31 as shown in FIG. 3, and wet paper P sandwiched between two upper and lower endless felts 33, 34 between the two. , A pressure belt 35 driven by the felt 34 is arranged between the lower felt 34 and the shoe 32, the pressure belt 35 is pushed up by the shoe 32, and the felts 33 and 34 are pressed against the roll 31. This device forms a wide nip area and improves the water squeezing effect by the surface pressure between the roll 31 and the shoe 32.

In the wide nip press described above, the pressure belt 35 is relatively long, and is stretched over a plurality of (four in the figure) rolls 36.
It shows a type that runs with a certain tension,
As shown in FIG. 4, there is also a type in which a relatively short pressure belt 35 is run with almost no tension.

As shown in FIG. 5, one side (or both sides) of the base fabric 51 made of double or triple weave is formed of a high hardness synthetic resin layer (eg, polyurethane, acrylonitrile butadiene, etc.) 52 as shown in FIG. Cover, the formation surface of the synthetic resin layer 52 is brought into contact with the shoe, the base cloth exposed surface 53 without the layer 52 is run in contact with the felt, and the water squeezed from the wet paper is retained in the base cloth 51. Was. Therefore, when the void volume (void volume) of the base cloth 51 was small, the water squeezing ability was reduced.

Although not shown, in the pressure belt in which the synthetic resin layers are formed on both surfaces of the base cloth 51, drainage grooves are provided in the synthetic resin layer on the side in contact with the felt to improve the water squeezing rate.

[Problems to be solved by the invention]

The base fabric 51 of the pressure belt 35 is usually composed of a warp 51 of an upper layer.
a, the lower layer of the warp 51b, the filling yarn 51c and the weft 51d are polyester monofilament or nylon monofilament,
Alternatively, since these are mixed and used, there are the following problems. That is, although nylon has good abrasion resistance, it has a drawback that it swells and expands in water, and polyester has less elongation than nylon, but has poor abrasion resistance.

When the pressure belt made of a nylon base fabric is used in a wide nip press of the type shown in FIG. 4 running with little tension, swelling occurs at the entrance N of the nip area.

In addition, there is also a problem that the length shrinks and becomes short between the time of manufacture and use, and the length and width of the sheet become unusable during use.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems and to provide a durable wide-width nip press pressure belt with little dimensional change.

[Means for solving the problem]

In order to achieve the above object, the present invention relates to a wide nip press pressure belt in which one or both surfaces of a base fabric are covered with a synthetic resin layer having high hardness, wherein the length of the yarn buried in the synthetic resin layer is All or some of the yarns in the direction are made of high-modulus heat-resistant fibers, for example, aromatic polyamide or aromatic polyester fibers, or polyetheretherketone fibers, so that dimensional stability can be ensured.

[Action]

Next, the operation of the present invention will be described with reference to the accompanying drawings.

In the figure, reference numeral 1 denotes a base cloth, and reference numeral 2 denotes a high-hardness synthetic resin layer covering one surface (lower layer) of the base cloth 1. It is preferable that the base fabric 1 has a warp double weave or warp triple weave structure with little change in the height direction with respect to a vertical external force under a high nip pressure. Reference numeral 3 denotes a warp (a yarn along the belt length direction), and the warp 3 is a first warp.
As shown in the figure, in the case of the warp double weave, it is composed of an upper layer warp 3a and a lower layer warp 3b. Further, as shown in FIG. 2, in the case of the warp triple weave, it is composed of an upper layer warp 3a, a middle layer warp 3a 'and a lower layer warp 3b. 4 is a weft (yarn along the width direction of the belt) and 5 is a filling yarn. The filling yarn 5 prevents the coating resin from leaking to the opposite surface when the synthetic resin layer 2 is coated on the base cloth 1 and also controls the penetration level L of the resin layer 2 in the base cloth 1 over the entire belt. It has a function to make it uniform and a function to strengthen the bonding force between the base fabric and the synthetic resin layer. The filling yarn 5 is completely buried in the synthetic resin layer 2.

The lower warp 3b and the filling yarn 5 buried in the synthetic resin layer 2 are made of fibers having high modulus and excellent thermal stability in order to secure dimensional stability. Or a configuration in which there is almost no dimensional change due to heat treatment. Specifically, aromatic polyamide fiber, aromatic polyester fiber, or polyetheretherketone fiber (PEEK) is used.

Here, the warp and the filling yarn covered with the synthetic resin layer are made of the high modulus fiber, so that there is almost no dimensional change due to tension and heat treatment during the manufacturing process, and the surface not covered with the resin is formed. As the weft and the upper warp 3a, 6 nylon monofilament having high friction durability is used.

Also in the case of a pressure belt in which both surfaces of the base fabric are covered with a synthetic resin layer, a pressure belt with almost no dimensional change can be obtained by using a high modulus yarn for all or a part of the warp.

FIG. 6 shows a comparison between stress and strain curves of polyester and nylon used as the base fabric material of the conventional pressure belt, and aromatic polyamide fibers, aromatic polyester fibers, and polyetheretherketone of the present invention. Is shown.

The aromatic polyesters and aromatic polyamides used in the present application have a high modulus, extremely low elongation and high strength compared to nylons and polyesters, and have extremely good heat stability. In the process of coating the base fabric with the synthetic resin, the belt is subjected to tension and heat, so that a conventional pressure belt made of a base fabric made of nylon or polyester sometimes shrunk by as much as 15 mm in a few months after production.

In the base fabric of the present application, at least one of the warp or the filling yarn is composed of at least one of aromatic polyester, aromatic polyamide and polyetheretherketone fiber,
It is stable with very little change in height and width.

The warp of the base fabric is straightened by making the weave of the base fabric warp double and warp, so it does not stretch due to tension, and even if a vertical load is applied due to high nip pressure during use, the structure is There is almost no elongation because it does not collapse.

In addition, a pressure belt in which a synthetic resin is coated on at least one surface of a double woven or triple woven base fabric made of a high modulus, heat resistant fiber is used as a relatively short pressure belt which hardly receives tension. As a result, the swelling does not occur at the entrance of the nip region, and a unique effect that the nip region can be used stably for a long time is exhibited.

〔Example〕

○ First example Base fabric → warp double weave with filled yarn ・ Upper warp → 6 nylon 1,000d monofilament ・ Lower warp → polyester 1,000d monofilament ・ Filled yarn → aromatic polyamide (brand name Kevlar) 3,00
0d multifilament, weft → 6 nylon 1,240d monofilament The lower layer of the base fabric was covered with a polyurethane resin so that the filling yarn was buried, to obtain a 2.90 mm thick pressure belt.

○ Second example Base fabric → Triple weave with filled yarn ・ Upper warp → 6 nylon 1,000d monofilament ・ Middle warp → Aromatic polyester (trade name “Vectran”) 1,000d monofilament ・ Lower warp → Same as middle warp Filled yarn → polyester 3,000d multifilament ・ Weft → 12 nylon 1,540d monofilament The lower layer of the base fabric was covered with polyurethane resin so that the filled yarn was buried, and a 3.10 mm thick pressure belt was obtained.

○ Comparative example Base cloth → warp double weave with filling yarn ・ Upper layer warp → 6 nylon 1,000d monofilament ・ Lower layer warp → polyester 1,000d monofilament ・ Filling thread → 66 nylon 3,000d multifilament ・ Weft → 6 nylon 1,240d monofilament The lower layer of the base fabric was covered with a polyurethane resin so that the filling yarn was buried, thereby obtaining a pressure belt having a thickness of 2.90 mm.

The pressure belts obtained as the first example, the second example, and the comparative example (conventional example) have a modulus of 1% and a modulus of 2
A characteristic test was performed on% modulus, elongation in water at 20 ° C., and shrinkage after storage for 3 months, and the results in the following table were obtained.

The test of elongation in water is the dimensional change after immersion in water at 20 ° C. for 48 hours.

As a result, the first example and the second example of the present application both have significantly improved modulus and significantly improved elongation in water, as compared with the comparative example (conventional product). It can be seen that the dimensional change was significantly improved.

Also, it can be seen that the shrinkage of the product after completion is less than 1/3 that of the conventional product.

〔The invention's effect〕

As described above, the present invention relates to a wide-width nip press pressure belt in which one or both sides of a base fabric are covered with a high-hardness synthetic resin layer, and all or a part of the warp thread buried in the synthetic resin layer has a high modulus. Because it is composed of heat-resistant fiber,
This has an excellent effect that a pressure belt for a wide nip press having excellent durability and almost no dimensional change can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing a pressure belt of a first embodiment of the present invention, FIG. 2 is a schematic cross-sectional view showing a pressure belt of a second embodiment, and FIGS. FIG. 5 is a schematic cross-sectional view showing a pressure belt of a conventional example (comparative example), and FIG. 6 is a graph showing a characteristic curve of a base fabric material. DESCRIPTION OF SYMBOLS 1 ... Base fabric 2 ... Synthetic resin layer 3 ... Warp 4 ... Weft 5 ... Filling yarn

Claims (1)

(57) [Claims] In a pressure belt for a wide nip press in which a part of a base cloth is exposed and covered with a synthetic resin layer having high hardness, all or a part of a warp thread buried in the synthetic resin layer has a high modulus. A pressure belt for a wide nip press, comprising a heat-resistant fiber made of aromatic polyamide or aromatic polyester, or polyetheretherketone.