CN1069369C - Fabrics for Paper Machines - Google Patents

Abstract

A papermaker's fabric (10) is woven from warp yarns (11, 19, 20) and one or more layers of weft yarns (12-18). The weft yarns (12-18) of at least one layer comprise relatively coarse (12, 13, 16, 17) and relatively fine (14, 15, 18) yarns. The warp and weft yarns (11, 19, 20) are arranged such that: on the surface of the fabric, the warp yarns (11, 19, 20) form outer floats or knuckles, and the inner floats or knuckles in the fabric body surround the finer weft yarns (14, 15, 18) in one weft layer. The portion of the warp yarns on one surface that forms the inner floats or knuckles does not extend to the plane of the face of the fabric.

Description

Fabrics for Paper Machines

The present invention relates to a fabric for a paper machine, in particular to a fabric for the drying section of a paper machine, although other uses are of course not excluded.

Generally speaking, a paper machine consists of three major parts, namely the forming part, the pressing part and the drying part. In each section, a fabric belt is used to convey a continuous sheet of paper through the papermaking equipment on which the sheet is made. Since each section of the paper machine has different requirements, the construction of the fabric used in each section is also different. For example, forming fabrics have both good permeability and surface properties. The former can provide the required drainage, while the latter should match the type of fiber being processed. A press fabric belt must be able to quickly absorb and drain water. At the same time, it can protect the newly formed paper. Drying fabrics should be heat resistant, durable under adverse chemical and physical conditions, and have good permeability.

Disclosed in the patent application WO 91/19044 is a drying fabric for a paper machine, which is formed by interweaving flat yarns in the warp direction and yarns in the weft direction. During manufacture, the upper and lower surfaces of the fabric should be With some floats. These floating yarns provide a smooth fabric surface. The warp yarn system consists of upper and lower yarns arranged vertically up and down in order to control the permeability of the fabric. The warp yarns are woven close to each other to reduce the permeability of the fabric and to lock the warp yarn pairs in the warp direction.

In a paper machine, the drying fabric is passed over drying rolls. Here the fabric is subjected to intense heat on the side of the roll and is subject to steam breakthrough degradation (but more predominantly from the side carrying the paper) due to the nature of the paper being made and/or rusting of the felt rolls Or corrosion, will also cause wear on both sides of the fabric, degradation of the edge of the belt is particularly problematic, because the edge is always in contact with the heated drying roller.

It is an object of the present invention to provide a paper machine fabric which is highly resistant to degradation due to heat, hydrolysis and abrasion.

The invention provides a fabric for a paper machine, which is formed by interweaving warp yarns and one or more layers of weft yarns, characterized in that at least one layer of weft yarns contains yarns of different thicknesses, and , these warp and weft yarns are arranged such that the warp yarns define outer floats or knucles on one surface of the fabric, and, in a layer of weft yarns, Underneath, the inner floats or knots are defined around the thinner weft yarns, wherein the portion of the warp yarns that define the inner floats or knots below said one surface does not extend to the fabric The planes on which the fronts lie and are separated by air.

Preferably all weft yarn layers include thick and thin yarns. And it is preferable that both above-mentioned surfaces of the fabric have floats made of warp yarns, and that all inner warp floats or knots are located within the fabric body, that is, between the above-mentioned two surfaces of the fabric.

The fabric of the invention is particularly suitable for use as a drying fabric, although other uses are not excluded.

Since the floats or nubs of the warp yarns do not extend to the surface of the fabric, the facing surfaces of the yarns are insulated by the air from the heat generated by the drying rolls. The papermaker's fabric of the present invention has good resistance to thermal degradation due to the better insulating properties of air than fabric, and at the same time, the increased distance of the yarn from the surface of the fabric increases its resistance to degradation by abrasion and hydrolysis Resistance. This is most important for the drying part of the paper machine.

The warp floating yarns existing on one surface of the fabric and the warp floating yarns existing on the front surface may be the same material or different materials. The same or different materials may be used to manufacture the weft yarns present on one surface of the fabric as well as its face and/or within individual weft yarn layers. Materials suitable for warp yarns include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyamides, polyphenylene sulfide (PPS), polyethers Etherketone (PEEK), or PCTA (copolymer of cyclohexanedimethanol with terephthalic and isophthalic acids). One suitable fabric is made entirely of polyester (such as PET), while another has warp yarns of polyester material on the back of the fabric and high performance warp yarns on the opposite side. Yarn (eg PPS, PEN or PEEK).

Since the warp yarns on one face of the fabric in the dryer section of the paper machine are not in contact with the opposite face of the fabric, the warp yarns on the paper side of the fabric will not be in contact with the dryer rolls, so it will not Withstands extremely high temperatures. Therefore, it is not required that the yarn has good resistance to degradation by heat or abrasion. The yarns on the opposite side of the fabric can be selected to provide improved abrasion and heat resistance.

Thus, by selecting suitable materials for the warp yarns on both surfaces of the fabric, the working life of the fabric can be increased.

The weft yarn is generally made of polyester (such as PEN, PCTA), PPS, PEEK or a combination thereof.

Another novelty of the present invention is the use of different combinations of weft yarn dimensions in order to control their permeability. Typical weft yarn sizes are 0.3mm in diameter, alternatively 0.6mm, 0.4mm or 0.2mm. WO 91/19044 realizes the control of its permeability by changing the number of warp and weft yarns in the fabric. This approach has a disadvantage compared to changing the diameter of the weft yarns because it takes time to readjust the loom. Other methods used to control penetration include inserting weft stuffing yarns, varying the number of warp yarns, varying the density of weft yarns, and using non-circular or multiple weft and/or warp yarns .

Examples of combinations of different diameters used in the weft direction may be 0.5mm and 0.7mm; 0.5mm and 0.8mm; 0.5mm and 0.9mm; and 0.4mm and 0.9mm. The weft yarns preferably vary in diameter from 0.1 mm to 0.6 mm.

In a preferred embodiment of the invention, the fabric comprises at least two layers of yarns in the weft direction. Preferably all weft yarn layers comprise thicker and thinner yarns. Whether in any single weft yarn layer or in vertically adjacent yarn layers, the thick and thin yarns preferably appear in an alternating pattern. In a preferred embodiment of the invention, "stuff" weft yarns are also included to control their permeability. It is added by weaving weft yarns with a large surface area into the fabric. The use of such additional yarns will reduce the permeability of the fabric. These additional yarns are preferably topographical yarns.

The warp yarns of the present invention are preferably flat monofilaments having an aspect ratio preferably in the range of 2:1 to 4:1. Of course, yarns of other configurations (ie non-circular in cross-section) may also be used, such as triangular cross-section yarns. Warp yarns of circular cross-section can also be used. The use of "D" shaped yarns is especially suitable. The yarn should be used with its curved surface facing the body of the fabric. This curved surface improves the stain resistance and allows easy yarn cleaning (with high pressure air/water flow). The fabric may contain warp yarns of different cross-sectional sizes and/or shapes, eg, as an alternative, certain yarns may be kept out of contact with the paper and/or drying rolls.

Preferably, the warp yarns float over at least two larger diameter weft yarns, and any smaller diameter weft yarns therebetween, thereby forming a float. In a multi-ply fabric, the knuckles formed by the warp yarns on opposite sides of the fabric will form in the fabric below the weft yarns.

In order to facilitate the understanding of the present invention, some special embodiments of the present invention will be described below with reference to the accompanying drawings:

Fig. 1 is the side view of a kind of fabric of the present invention;

Figure 2 is a side view of a second fabric of the present invention.

Referring to FIG. 1 , the fabric 10 includes a yarn layer formed by alternating thick and thin weft yarns. A first warp yarn 11 extends over two thicker warp yarns 12, 13 and over a thinner weft yarn 14 in between to form a float. This yarn is then passed under a thinner weft yarn 15 to form a knot, then over another pair of thicker weft yarns 16, 17 and a thinner weft yarn Above yarn 18, the majority of warp yarns 11 are located on the upper surface of the fabric. The portion of the warp yarns 11 forming the knots does not extend to the lower surface of the fabric, and other warp yarns 19 on the upper surface of the fabric are arranged in the same manner. The warp yarns 20 on the lower surface of the fabric float below two thicker warp yarns and one thinner weft yarn in between. This yarn is then passed over a thinner weft yarn, forming a knot, and then passed through the back of two other thicker weft yarns with a thinner weft yarn in between. above. The warp yarns on the lower surface of the fabric do not extend to the upper surface of the fabric. In use, the fabric is formed into a belt for use in a paper dryer. The yarns on one surface of the fabric will support the paper, they are generally made of PPS, PEN, PEEK or PCTA, which have good resistance to degradation by heat, steam and abrasion. The yarns on the other side of the fabric are generally made of polyester, which has good resistance to dry heat degradation.

Figure 2 shows another fabric 21 of the present invention having two layers of weft yarns 22, 23, each layer comprising thicker and thinner weft yarns in alternating arrangement. The two layers of weft yarns are preferably stacked in the following way, but it is not absolute, that is, a thinner weft yarn is located above a thicker weft yarn, and a thicker weft yarn is placed on top of a thicker weft yarn. The yarn of the is placed on top of a thinner weft yarn.

A warp yarn 24 floats over the upper surface over two thicker weft yarns 25, 26 and a thinner weft yarn 27 in between. The yarn passes under a thinner weft yarn 28 in the upper layer 22 and under a thinner weft yarn 29 in the lower layer 23, and then passes through another thinner weft yarn 29 in the upper layer 30. Thin weft yarns. The warp yarns 24 repeat the above pattern along the length of the fabric. Other warp yarns 31 located on the upper surface are similarly arranged. The warp yarns 32, 33 of the lower surface are arranged in a mirror image relationship to the weft yarns of the upper layer.

As previously mentioned, the warp yarns forming the floats at the bottom of the fabric do not extend to its upper surface, and the warp yarns forming the floats on the upper surface of the fabric do not extend to the lower surface of the fabric.

It should be understood that the above-mentioned implementation examples are only for the purpose of illustration. Many improvements and variations can be made thereto.

Claims (16)

1, the fabric that a kind of paper machine is used, it is made into by the yarn of warp-wise and the yarn of one or more layers broadwise, it is characterized in that in one deck weft yams, including at least thicker and thinner yarn, the arrangement mode of the yarn of warp-wise and broadwise is: on a face of fabric, the yarn of warp-wise limits outside float or knot, inner float or knot then are positioned at described below, yarn around broadwise thinner in the weft yams layer, wherein, the yarn that constitutes that part of warp-wise of inner float or knot below described does not extend to the plane at the positive place of this fabric, and by air that they are spaced apart.

2, paper machine fabric as claimed in claim 1 is characterized in that all weft yams layers all comprise thicker and thinner yarn.

3, paper machine fabric as claimed in claim 1 or 2 is characterized in that the float of the warp-wise on described of fabric and the warp-wise float of this fabric face make with identical materials.

4, paper machine fabric as claimed in claim 1 or 2 is characterized in that the float of the warp-wise on described of fabric is to make with different materials with the float of warp-wise on this fabric face.

5, paper machine fabric as claimed in claim 1 is characterized in that this fabric comprises the yarn of several layers broadwise, on described of fabric with its front on the yarn of broadwise adopt different materials to make.

6, paper machine fabric as claimed in claim 1 is characterized in that the float of the warp-wise on face of fabric comprises polyester, and comprises PPS at the warp-wise float of this fabric face, PEN or PEEK.

7, paper machine fabric as claimed in claim 2 is characterized in that thicker and thinner weft yams, and the scope of its diameter difference is 0.1mm～0.6mm.

8, papermaker's fabric as claimed in claim 2 is characterized in that the yarn of thicker and thinner broadwise occurs with alternant in any one deck weft yams layer.

9, paper machine fabric as claimed in claim 8 is characterized in that this fabric comprises not only one deck weft yams, and the yarn of thicker and thinner broadwise alternately occurs in the layer of vertical direction.

10, paper machine fabric as claimed in claim 1 is characterized in that this fabric also comprises the additional filling yarn of broadwise.

11, paper machine fabric as claimed in claim 10, the cross section that it is characterized in that this filling yarn is non-circular.

12, paper machine fabric as claimed in claim 1, the cross section that it is characterized in that the yarn of its warp-wise is non-circular.

13, paper machine fabric as claimed in claim 12, the yarn that it is characterized in that warp-wise is a flat monofilament, its aspect ratio is 2: 1～4: 1.

14, paper machine fabric as claimed in claim 12, the shape that it is characterized in that the yarn of warp-wise is " D ", its curved surface is in this fabric body.

15, paper machine fabric as claimed in claim 1 is characterized in that the size and/or the shape of its cross section of warp yarn that this fabric is contained is different.

16, paper machine fabric as claimed in claim 1 is characterized in that this fabric is a dry fabric.

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