US2520202A - Treatment of filaments, foils, and similar articles - Google Patents

Description

Aug 29; 1950 fr. a. FREARsoN Erm. 2,520,202

0F FILAIENTS, FOILS AND SIIILAR ARTICLES File@ Jan. a. 1947 J Allorneyg` Patented Aug. 29, 1950 TREATMENT F FILAMENTS, FOILS, AND SIIVIILAR ARTICLES Thomas Barnard Frearson and Thomas Jackson, Spondon, near Derby, England, assignors to Celanese Corporation of America, a corpora-l tion of Delaware Application January 8, 1947, Serial No. 720,856 In Great Britain January 21, 1946 This invention is concerned with improvements in or relating to stretching and other treatments of illaments, yarns, foils and similar products carried out during their travel through a fluid under pressure, and to apparatus for carrying out such treatments.

It is well-known that the tenacity oi iilaments, yarns. foils and similar articles made of organic derivatives of cellulose and other polymeric compounds may be improved very considerably by stretching them in the presence of steam or other stretch-assisting agent. For example, U. S. application S. No. 4,510, filed February 1, 1935, now abandoned, describes the stretching of continuous iilaments and threads made of cellulose acetate in the presence of saturated or wet steam under pressure, and U. S. Patent No. 2,142,909 describes an improved apparatus in which the materials pass first through an end pressure chamber containing a positively driven feed device for the materials and then into a stretching chamber. Both of these specifications indicate that the means for introducing the steam into the stretching chamber is preferably such as to direct the steam on to the filaments or threads immediately upon their entry into the chamber.

The methods and apparatus described in these and other patents give very valuable results as regards the tenacity of the iilaments and other articles produced and it is possible, as described in the above specifications, to stretch yarns to more than fty times their original length if desired and to double or treble their original tenacity. We have, however, now discovered that it is not essential that the steam should be directed on to the articles immediately upon their entry into the stretching chamber but that, on the contrary, it is advantageous to protect them from the direct impact of the steam, particularly lwhen yarns of high denier, such as are employed in the production of tyre cords and the like, are to be stretched. Such yarns usually consist of a number of ends and may have a total denier, for example, of 5,000, 10,000, 15,000 or even 20,000.

The protection of the yarns from the direct impact of the steam, which may be moving with a high velocity, may be carried out merely by interposing a shield between the yarns and the steam inlet orifices, but preferably the yarns are caused to pass through an open-ended box or shroud at that portion of their path through the stretching chamber where they would otherwise be subjected to the impact of the steam, and the steam inlet orifices are so arranged that the steam impinges on the outer side of the shroud Claims. (Cl. 28--59.5)

and not on the yarns. The width and depth of the shroud employed should be such that the yarns can pass easily through it without any risk of their rubbing against it. It may, for example, be six to twelve inches wide, depending on the number of ends of yarn dealt with by the machine, and one to two inches deep. Its length, in the direction of travel of the yarns, should be suiiicient completely to shield the yarns from the jets of steam entering the stretching vessel. Usually a length of three to six inches is sufficient.

When, as is preferred, the steam is introduced near the orifices through which the yarns enter the stretching chamber, the shroud may consist of an open-ended box xed to the wall containing the yarn inlets and surrounding these inlets, or xed to a separate removable plate provided with an opening for the passage of the yarns and adapted to be positioned in contact with or adjacent to the wall containing the yarn inlets.

The steam inlets may consist of a large number of very small orifices, but it has been found preferable to use fairly large inlet oriiices having a diameter, for example, of als" or or even one or more large oriiices having a size, for example, of 1 x 1/4. An advantage of the use of the larger orifices is that they are less likely to become blocked by particles of solid matter present in the steam, with the result that maintenance costs arising from the necessity for cleaning the oriiices are reduced.

A stretching machine embodying the invention is illustrated in the accompanying drawing. The machine comprises yarn feeding means and take-up means (not shown), and between them an end pressure box I and a stretching chamber 2 having as a common end wall with the end pressure box I a plate 3. The end pressure box I is provided with orifices at one end for the entry of the yarns (not shown) and at the other end with orices 4 in the plate 3 for their passage into the stretching chamber 2; the stretching chamber is provided with orifices 5 in its output end for the passage of the yarns to the take-up means. The cross-section of the orices in the end pressure box and in the plate 3 is substantially equal to that of the unstretched yarn, while that of the orifices 5 is substantially equal to that of the yarn after it has been stretched.

In the stretching chamber 2 a plate 6 is clamped to the plate 3 with suitable packing to eiect a perfect seal between the two plates. The plate 6 is provided with a slot 'l of such shape and size as to allow the free passage of yarn from each of the oriiices 4, and around this slot is fixed a shroud 8 extending perpendlcularly to the plate 6 for 3 to 6 inches into the stretching chamber I. The stretching chamber 2 also comprises a steam iet plate 9 consisting of steam inlets I0, channels I I above and below the shroud 8, and orifices I2 in the walls of the said channels whereby steam is caused to enter the stretching chamber and impinge on the outer surfaces of the shroud l.

As has already been stated, the invention has been found to be particularly valuable in the stretching of yarns of high denier, such as are used for the production of tyre cords and beltings. Not only are the stretched yarns more uniform and the stability of stretching better, but also the invention makes it possible to stretch bundles of a higher total denier than in the absence of a shroud. A number of yarns, e. g. in warp formation, can be stretched simultaneously Without loss of uniformity. For example, in the production of stretched yarns for tyre cords it has been found that by using a shroud nine inches wide, one inch deep and three inches long fixed round the orifices through which the yarns enter the stretching chamber it is possible to stretch a set of -25 bundles of yarn, each bundle having a denier four t'mes as great as could be stretched satisfactorily in the absence of the shroud. Moreover. the use of a shroud also makes it possible to increase the load on the machine, expressed in terms of denier per unit width of feed roller, even though the number of ends per unit width is reduced as a result of the increase in the denier per end. In consequence the theoretical output per unt time of a machine has been increased by nearly 40% and this, coupled with improved efficiency due to quicker starting and longer runs also resulting from the use of the shroud, has resulted in an increase in production per machine of over '70%.

Though the invention is of the greatest value for the stretching of yarns of high denier, it is applicable in general to stretching and other treatments of yarns, especially cellulose acetate yarns, filaments, foils and similar articles carried out during their travel from one point to another 4 ments, yarns. foils and similar articles made of thermoplastic polymeric compounds other than those made of organic derivatives of cellulose. Examples of such compounds are polyvinyl acetate, polyvinyl chloride. polyvinyl acetate-vinyl chloride and polyvinylidene chloride.

The invention has been described with particular reference to the types of stretching apparatus illustrated in U. S. application S. No. 4,510, filed February 1, 1935, and U. S. Patent No. 2,142,909 but it is to be understood that the principle is applicable generally to apparatus used for stretchlng and other treatments in which fluid media, particularly gaseous media, are introduced under pressure. For instance, in apparatus provided with an injector device such as is described in U. S. application S. No. 472,460, filed January l5, 1943, now Patent No. 2,450,045, of T. Jackson and F. B. Hill; the orifice I2 through which the yam enters the stretching chamber may be prolonged so as to protect the yarn from the direct impact of the steam or other fluid introduced through the annular orifice 5.

Having described our invention, what we desire to secure by Letters Patent is:

1. In apparatus for stretching yarns in warp formation in wet steam under pressure comprising a. pressure stretching chamber having inlet and outlet orifices for the yarns, each orifice being substantially of the same size and shape as the cross section of the yarn to pass through it, and

having close to, but separate from, the inlet orifices for the yarns, inlets for the steam directed towards the path of the yarns near to the inlet orifices for the yarns so that the steam would normally impinge directly on the yarns, the improvement which consists in the provision of a shroud surrounding the path of the yarns in the vicinity of the yarn inlet orifices and sufficiently long to prevent the steam from impinging directly on the yarns, said shroud being interposed through a vessel containing a fluid treat-ment agent under pressure. For example, cellulose acetate yarns of 250 to 500 denier may be stretched to ten times their original length in wet steam in the apparatus described in the present applicaf tion, and used for textile purposes, if desired after conversion into regenerated cellulose yarns by complete saponification. Cellulose acetate yarns of fine denier, e. g. 40-50, may also be successfully stretched to give very uniform products.

l In general the conditions for stretching articles made of cellulose acetate or other organic derivative of cellulose are similar to those described in the prior specification referred to above, though it has been found that when the shroud is in use it is preferable to employ a slightly higher steam pressure, e. g. higher by 1/2 pound per square inch, than in the absence of the shroud. The best results, especially when stretching yarns of high denier or when stretching to a high degree, e. g. to six, ten or more times the original lengthof the yarns, are obtained with ancapparatus having an end pressure chamberas described in U. S. Patent No. 2,142,909 in which case the end chamber preferably contains lwater at a pressure somewhat lower than that of the steam, for instance about 2 to 5 pounds per square inch below the steam pressure.

As already stated the invention is also applicable to stretching and other treatments of filabetween the steam inlets and the path of the yarns whereby the steam impinges on said shroud, and said shroud being freely open to the pressure treatment chamber-whereby the steam is present onall sides of said shroud and is in a relatively quiescent statement when it initially contacts the yarns.

2. In apparatus for stretching yarns in warp formation in wet steam under pressure comprislng a pressure stretching chamber having inlet and outlet orifices for the yarns, each orifice being substantially of the same size and shape as the cross section of the yarn to pass through it, and having close to, but separate from, the inlet orifices for the yarns, inlets for the steam directed towards the path of the yarns near to the inlet orifices for the yarns so that the steam would normally impinge4 directly on the yarns, the improvement which consists inthe provision 0f a removable plate in contact with the wall of the chamber containing the inlet orifices for the yarns, the said plate being provided with an opening in front of the said inlet orifices by means of which the yarns pass through the plate, and with Ka shroud mounted round the said opening and extending into the chamber, the length of the shroud being suflicient to prevent the steam from impinging directly on the yarns, said shroud being interposed :between the steam inlets and the path of the yarns whereby the steam impinges on said shroud, and said shroud being freely open to the pressure treatment chamber whereby the steam is present on all sides of said shroud and is 5 in a relatively quiescent state when it yinitially contacts the yarns.

3.-In apparatus for stretching yarns in warp formation in wet steam under pressure comprising a pressure end chamber having inlet and outlet oriilces for the yarns and contiguous therewith a pressure stretching .chamber having inlet and outlet oritlces for the yarns, each of all the said oriilces being substantially of the same size and shape asthe cross section of the yarn to pass through it, and having close to, but separate from, the inlet oriilces for the yarns into the stretching chamber, inlets for the steam directed towards the path of the yarm so that the steam would normally impinge directly on the yarns. the improvement which consists in the provision in the stretching -chamber o! a shroud surrounding the path of the yarns in the vicinity oi-the yarn inlet oriilces and suillciently long to prevent the steam from impinging directly on the yarns. said shroud being interposed between the steam inlets and the path oi.' the yarns whereby the steam impinges on said shroud. and said shroud being freely open to the pressure treatment chamber whereby 'the steam is present on all sides of said shroud and is in 'a relatively quiescent state when it initially contacts the yarns.

4. In apparatus for stretching yarns in warp -formation in wet steam under pressure comprising a pressure end chamber having inlet and outlet orices for the yarns and contiguous therewith a pressure stretching chamber having inlet and outlet orices for the yarns, each of all the said oriilces being substantially of the same alle and shape as the cross section of the yarn to pass through it. and having close to, but separate from, the inlet oriiices for the yarns into the stretching chamber. inlets for the steam dirccted towards the path of the yarns so that the steam would normally impinge directly on the yarns, the improvement which consists in the provision oi' a shroud 3 to 6 inches long sur- :rounding the path oi' the yarns in the vicinity oi' the yarn inlet orifices to prevent the steam from impinsins directly on yarns, said shroud being interposed between the steam inlets and the path oi the yarns whereby the steam impinges on said shroud. and said shroud being freely open to the pressure treatment chamber whereby the steam is present on all sides of said shroud and is in a relatively quiescent state when it initially contacto` the yarns. v

5. In apparatus for stretching yarns in warp formation in wet steam under pressure comprising a pressure end chamber having inlet and outlet,oriilces for the yarns and contiguous therewith a pressure stretching chamber having inlet and outlet orices for the yarns, each of all the said orlilces being substantially of the same size and shape as the cross section of the yarn to pass through it. vand having close to. but separate from. the inlet oriilces for the yarns into the stretching chamber, inlets for the steam directed towards the path of the yarns so that the steam would normally impinge directly on the yarns, the improvement which consists in the provision of a removable plate in contact with the wall of the stretching chamber containing the inlet oriilces ior the yarns, the said plate being provided with an opening in front of the said inlet oriilcas by means of which the yarns pass through the plate. and with a. shroud mounted round the said opening and extending into the chamber for a length of 3 to 6 inches to prevent the steam from impinging directly on yarns, said shroud rbeing interposed between the steam inlets and the path of the yarns whereby the steam impinges on said shroud, and said shroud being freely open to the pressure treatment chamber whereby the steam is present on all sides of said shroud and is in a relatively quiescent state when it initially contacts the yarns.

i THOMAS BARNARD FREARSON.

THOMAS JACKSON.

REFERENCES CITED The following references are of record in the ille of this patent:

UNITED STATES PATENTS Number Name Date 1,738,947 Chapin Dec. 10, 1929 2,142,717 Dreyfus et al Jan. 3, 1939 2,142,909 Moncrien et al. Jan. 3, 1939 2,265,273 Dreyfus Dec. 9, 1941 2,276,364 Alford et al. Mar. 17, 1942 2,276,394 Hill et al Mar. 17, 1942 2,346,186 Poesl Apr. 11, 1944 2,371,579 Cole et al Mar. 13, 1945 2,398,856 Reel Apr. 23, 1946 2,402,228 Jackson et al June 18, 1946 2,450,045 Jackson Sept. 28, 1948 FOREIGN PATENTS Number Country Date 440,653 Great Britain Dec. 30, 1935 466,802 Great Britain June 7, 1937 512,800 Great Britain 1----- Sept. 26, 1939

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