JPH0244959B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) This invention relates to a dryer canvas with good heat transfer efficiency that is used in a single-run method in a multi-tube dryer of a paper machine. (Prior art) As the paper making speed increases, fluttering and ballooning tend to occur, and since the paper strength of the sheet in the early stage of drying is low, this causes paper breakage and wrinkles, causing operational problems. Become. To solve this problem, the canvas can be hung up and down by 2
The single run method is being used instead of the single run method. This system has the disadvantage, on the other hand, that it leads to a reduction in dryness. Needle canvas, which has a uniform and mild contact surface, is preferred for the single-run method, but the drying efficiency was similar to that of woven canvas. To prevent this, improvements have been made to the canvas itself, such as by making the air permeability conditions more appropriate, or by adding mechanical auxiliary drying devices. Further, in order to improve heat transfer, Japanese Utility Model Publication No. 30385/1963 discloses the use of metal wires in some paper-making mesh fabrics. This discloses a structure in which the warp lines are a mixture of fiber threads and metal wires, the weft lines are metal wires, and the entire surface of the net fabric is occupied by the warp lines. (Problem to be Solved by the Invention) Generally, in the single-run method (shown in Figure 2), the wet paper comes into direct contact with about half of the number of heated cylinders during drying, and the other half comes into direct contact with about half of the number of heated cylinders during drying, and the other half come into contact with a canvas in between. heated. Therefore, there is less heat transfer in this area and the temperature of the paper is lower. Drying is therefore reduced compared to the conventional top-down system in which the wet paper is in direct contact on all cylinders. The net fabric disclosed in Utility Model Publication No. 30385 (1969) has a large content of metal wires, and therefore has a large weight and thickness, and its surface properties are not favorable. It was impossible to use the run method, and the purpose was rather different. The present invention is based on a single-run method, and aims to improve the heat conductivity of a felt-like canvas that is thin, highly flexible, and has mild contact with wet paper without losing its original characteristics. This product provides a needle canvas made of (Means for Solving the Problems) The structure of the present invention for achieving the above object is to provide a needle canvas in which a web is integrally laminated and polymerized on one side of a base fabric on a textile by needle punching. Metal fibers are mixed with the synthetic fiber threads constituting the web and the short fibers of the synthetic fibers constituting the web, and the mixing ratio of the metal fibers is 50% by weight, respectively.
It is based on the fact that it is within the range of 20% to 20%. Further, the metal fiber is a needle canvas characterized in that it is made of short stainless steel fibers or filament threads having a thickness of 700 d to 1500 d. (Function) The heat from the heated dryer cylinder is transferred to the needle canvas consisting of a base fabric and web mixed with metal fibers, and then to the wet paper that is traveling on the canvas, and the temperature of the wet paper is maintained at a certain level. It has a mechanism that raises the temperature to a certain level, improving heat transfer in a single dryer group. In addition, the heat capacity of the needle canvas increases, making it difficult to cool down even on the return path, contributing to improved drying. (Structure of the Invention) Fig. 1 is a longitudinal cross-sectional view of the needle canvas according to the present invention, and Fig. 2 is an explanatory diagram showing the travel path of the needle canvas and wet paper hung in a single type. . In FIG. 1, the needle canvas is made by laminating and polymerizing a web of synthetic fibers on a base cloth woven in a double weave using warp yarns 1 and weft yarns 2 by needle punching. The base fabric may be a single weave or a triple weave, but a double weave is preferred in terms of strength, thickness, and rigidity, and is most commonly used. The warp threads of the base fabric are polyester filament or polyester/nylon multifilament twists. Similarly, multifilament twisted yarns such as polyester are used as the weft yarns, and multifilament yarns made of metal fibers are twisted together with these twisted yarns. For example, metal fiber is 940d/
100f thick stainless steel wire is used. In general, it is preferable in terms of the production process to twist metal fibers into a helical shape using a twisting machine using a synthetic fiber as a core for the weft. The mixing ratio of metal fibers is 50% to 20% (weight ratio) of the yarn weight. If the metal fiber content exceeds 50%, the weight of the canvas increases, which makes it unsuitable for high-speed running, and also causes manufacturing difficulties and increases costs. On the other hand, if it is less than 20%, the effect will be less. After this base fabric is heat-treated, the web is placed on one side of the base fabric using a needle machine, and the web and base fabric are laminated and polymerized into one piece by pricking with a needle. The web is made of short fibers such as nylon, acrylic, polyester, and polypropylene, either alone or in combination.
50% to 20% short metal wire fibers (weight ratio)
Mix evenly. Metal wires are also short fibers, for example
Use 10μ x 75mm etc. It is preferable that the two be uniformly mixed in a preparation machine. As the metal fiber, stainless steel wire, aluminum, copper thin wire, and narrow products of the same film can be used. After needle punching, resin processing, hair burning, and calendering processes are applied as appropriate, similar to conventional products. (Example) The following table shows an example of this invention.

[Table] The results of laboratory heat transfer tests on this canvas are shown in Figure 3 as a temperature-time curve.
A sample canvas was placed on a cylinder heated to 100°C, and the temperature was measured every 5 seconds for 1 minute using a temperature sensor.
According to this figure, the temperature rise of No. 1, which contains metal fibers in the web and base fabric, is better than that of No. 2, which contains metal fibers only in the base fabric, and conventional product No. 3. It shows. (Effects of the Invention) By using the needle canvas configured as described above, the heat capacity of the canvas is increased and heat conduction is improved. In other words, when wet paper is placed on top of the canvas in a single-run drying method, the heat from the cylinder is easily transferred to the wet paper through the canvas, and the large heat capacity prevents the temperature of the entire canvas from decreasing, and the heated canvas Since it tends to be difficult to cool, it is effective in increasing the drying rate of wet paper. Furthermore, since the metal wires are mixed in to the extent that they do not impede the necessary conditions for a single-run needle canvas, there is no adverse effect on the wet paper at all. Furthermore, the life span of the canvas and other aspects are fully satisfactory to paper manufacturers.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of the needle canvas of the present invention, FIG. 2 is an explanatory diagram of the single run drying method,
FIG. 3 is the time-temperature curve of the heat transfer test. 1...Warp, 2...Weft, 3...Synthetic fiber, 4
...Metal fiber, 6...Dryer canvas.

Claims (1)

[Scope of Claims] 1. A dryer canvas that can be hung in a single run system, in which a web is integrally laminated and polymerized on one side of a woven base fabric using a needle punch, and the base fabric is constituted by a needle canvas. Excellent heat conductivity characterized by the fact that metal fibers are mixed with synthetic fiber threads and short synthetic fibers constituting the web, and the mixing ratio of metal fibers is within the range of 50% to 20% by weight. dryer canvas. 2. The dryer canvas according to claim 1, wherein the metal fibers are made of short stainless steel fibers or multifilament yarns having a thickness of 700d to 1500d.