UA55191A - Method for making filtering sleeves - Google Patents

Abstract

Method for making filtering sleeves is in knitting by round knitting machine seamless non-stretched sleeves with the stitch structure of those keeping base and weft threads. Those sleeves are knitted of synthetic threads, with the following calendering with smooth shafts; those are pressed to each other with pressure and heated.

Description

Description of the invention

The invention relates to methods of producing filter materials from synthetic fibers, and more specifically, to methods of producing knitted filter sleeves, which are used for filtering liquids and suspensions in various industries, in particular in the sugar industry.

The method of producing seamless, non-stretchable sleeves on a circular knitting machine is widely known, in which the main (longitudinal) threads forming the crown are laid in the spaces between the needles, the weft (transverse) threads are laid from the outside of the crown behind the backs of the tongue needles, and from the inside under the hooks needles 70 feed the loop-forming thread, from which loops are formed, covering the main threads from the wrong side, and the weft threads from the front side of the sleeve. (See, for example, Ass. of the USSR Mo193010, book: L.S. Smirnov, Yu.I Maslennikov,

V.Yu. Yavorsky, Technology of woven materials, Kyiv, "Technology", 1981, 121 p.). The materials produced in this way were called "woven" (DSTU 2319-93, term 23). To implement this method, circular knitting machines of the MAR type, which are used in the domestic knitting industry, have been developed. 719 The advantages of this well-known method are that seamless sleeves are produced with high productivity (20m/h - 25m/h). MAR machines can process various raw materials, yarn from natural and chemical fibers, complex synthetic threads. Therefore, MAR machines were used for the production of filter seamless sleeves for various purposes. But the filter sleeves, which are produced in the described way, have a significant, immanently characteristic defect: a relatively large through porosity, which occurs in the places of the transition of loops from the back to the front side of the sleeve. ,2dm Z/m2s, which is determined by DSGU 3028-95 "Synthetic textile filter materials for the sugar industry. General technical conditions".

This feature narrows the scope of application of woven filter sleeves. The disadvantage is aggravated when the sleeves are made from high-strength complex synthetic threads. In part, this defect can be eliminated by using textured plait threads as a weft (see patent of Ukraine Mo44199) and by increasing the knitting density.

Thus, the task arises to create such a method of producing seamless knitted filter sleeves that would combine high productivity of their knitting with the possibility of reducing end-to-end porosity and achieving water permeability of less than 2.2 dm Z/m2s, which would significantly increase the quality of the manufactured sleeves and - would expand the scope of their application. (22)

The problem is solved by the fact that in the method of producing filter sleeves, in which seamless non-stretch sleeves are knitted on a circular knitting machine, the loop structure of which holds the main and weft threads, the sleeves are knitted from synthetic threads, after knitting sleeves are calendered at a speed of (0.5 - 1) m/min) by smooth shafts that are pressed against each other with a force of (25 - 75) KN and heated to a temperature of 11770 - 15076.

The method can have an execution variant consisting in the fact that two or more sleeves are simultaneously calendered.

The temperature and pressure of the calender shafts are chosen depending on the nature of the synthetic threads used when knitting the filter sleeves. The combined effect of temperature and pressure during calendering causes " 20 densification of the yarns used and the knitted structure, which leads to a reduction in overall porosity, while the flattening of the warp, weft and loop yarns reduces through porosity. A decrease in total porosity c reduces air permeability by approximately 5-8 times, and a decrease in cross-sectional porosity reduces water permeability "c" by 9965 - 2395, depending on the type of synthetic threads that make up the filter sleeve. Calendering, compacting the structure of the sleeve, also reduces its thickness by 25905 - 3695. All this leads to the improvement of 415 filtering properties of the produced sleeves, increasing their quality and, therefore, competitiveness. sl The simultaneous calendering of two or more sleeves is intended not only to increase productivity, but also, more importantly, to prevent warping of the calender shafts. o The invention is explained by a drawing (Fig.), which shows the basic scheme of calendering. - Sleeves 1, 2 from "books" 3, 4 are placed on a belt conveyor 5, which brings them to the upper 6 and to the lower 7 rotating shafts of the calender. , 7 are heated to the temperature of SS. The shafts 6, 7, while rotating, grab the sleeves 1, 2 and pull them through at a speed of mm/min. The fields of the calender shafts, sleeves 1, 2 are cooled in the air and rolled into rolls 8, 9, or placed in "books".

The essence of the invention will be considered with examples.

Example 1. Production of sleeves for filtering aggressive liquids that contain strong acids.

On the MAR-98 circular knitting machine, which has a needle cylinder with a diameter of 98 mm and 108 reed needles, a sleeve is knitted using polypropylene complex thread 93.5 tex x 2 as a base, weft - polypropylene complex thread 222.2 tex and in the loop polypropylene complex thread 33, Zteks x 2KO. The knitting density is 83 loop rows and 37.5 loop columns per 100 mm, the linear density of the sleeve is 131 g/m. Calendering of two sleeves is carried out at the same time at a speed of 0.65 m/min with smooth shafts with a diameter of 220 mm, which are heated to a temperature of 1177 - 1207 C and compressed with a force of 75 KN. The test results of the filter sleeves obtained in this way are shown in Table 1. bo Indicator After knitting (After calendering Change in indicator 95 -Д-

According to the obtained indicators, the filter sleeve produced according to example 1 meets the user's requirements.

Example 2. Production of sleeves for filtering aggressive liquids containing strong acids. 70 On the MAR-98 circular knitting machine, which has a needle cylinder with a diameter of 98 mm and 108 tongue needles; knit the sleeve using polypropylene complex thread 93, btex x 2 as a basis, and wefts and loops - polypropylene complex thread 10Otex. The knitting density is 75 loop rows and 38 loop columns per 10 Ohm, the linear density of the sleeve is 116 g/m.

Calendering of two sleeves is carried out at the same time at a speed of 0./m/min with smooth shafts with a diameter of 220 mm, 75 which are heated to a temperature of 11672 - 1207"С and compressed with a force of 75KN. The indicators of the filter sleeves obtained according to this example are given in table 2 | and «

According to the obtained indicators, the filter sleeve according to example 2 also meets the user's requirements

Example 3. Production of filter sleeves for the sugar industry.

On the MAR-98 circular knitting machine, which has a needle cylinder with a diameter of 98 mm and 108 reed needles, the sleeve is knitted using as a base kapron complex thread 187tex, weft - kapron plait THREAD - Che ZOtex x 2, loops - a thread composed of two kapron complex threads 2 Otex and 15, btex. The density of knitting is 90 loop rows and 40 loop columns per 100 Ohm, linear thicker sleeve - 116bg/m o

Calendering of two sleeves is carried out at the same time at a speed of O0.67m/min with smooth shafts with a diameter of 220mm, "-- which are heated to a temperature of 1387 - 1407"С.

Is) h 2 s i i?

These indicators of the filter sleeve for the sugar industry, obtained by the proposed method, 5 indicate that it belongs to one of the best filter materials for this purpose. c The given examples do not exhaust the possible options for implementing the proposed method. From the examples given, it follows that the proposed method of manufacturing filter sleeves gives a significant positive effect, which is manifested in a significant improvement of the filtering properties in terms of air permeability, water permeability and thickness. at 50 shk

Claims (2)

The formula of the invention 1. The method of manufacturing filter sleeves, in which seamless double non-stretch sleeves are knitted on a circular knitting machine, the loop structure of which holds the main and weft threads, which differs in that the sleeves are knitted from synthetic threads, after knitting the sleeves calendered at a speed of 0.5-1 m/min with smooth shafts, which are pressed together with a force of 25-75 kN and heated to a temperature of 11770 - 15076. 2. The method according to claim 1, which differs in that two or more sleeves are simultaneously calendered. 60 b5