Process For The Continuous Shrinkage Of Random Webs

Abstract

A process for the shrinkage of random webs which includes the steps of drawing-in a web of textile material to be treated, freely guiding the web of textile material over a distance which is at least equal to the width of the untreated web of textile material and which is substantially vertical, pleating the width of the web of textile material to form a wave-like fleece, conveying the pleated wave-like fleece over the conveying surface of at least one sieve means and passing a heated fluid processing medium through the conveying surface and through said fleece and thereafter removing the treated fleece from the conveying surface of said sieve means. Drawing-in the web is effected to provide overfeeding in the length of the web onto the seive means.

Parent Case Text

This is a division of application Ser. No. 880,350, filed Nov. 26, 1969, now U.S. Pat. No. 3,713,219 granted Jan. 30, 1973.

Description

BACKGROUND OF THE INVENTION

The present invention relates to a process for the production of felts, particularly synthetic leather, by shrinking a continuous random web consisting essentially of at least two fiber types, one fiber type shrinking more under the influence of heat than the other. The continuous random web is advantageously needled before shrinkage and heated shock-like to the fixing and shrinking temperature by means of a processing medium, according to co-pending patent application Ser. No. 850,549 filed Aug. 15, 1969, now abandoned.

The parent application describes a process and an apparatus for the production of felts departing from a continuous random web wherein the continuous random web is heated shock-like to the shrinking temperature. The continuous random web is overfed in width and preferably in length to the processing medium. Overfeeding in width is necessary in order to safeguard a perfect and uniform shrinking in width of the fleece. Even if the fleece is fed freely to the processing medium, i.e., without any overfeed in its width, the high degree of shrinkage which can amount to 50 percent, causes a curve formation, i.e., shrinkage is more pronounced at the edges than in the middle of the fleece. Therefore, it has been suggested to feed the material to the processing medium in waves. This will ensure an essentially more uniform shrinking of the material.

SUMMARY OF THE INVENTION

An object of the present invention is to avoid the prior art disadvantages in the process for the production of felts.

Another object of the present invention is to provide an improved process for producing a uniform shrinkage of the material during the treatment process.

Tests have shown that the uniformity of shrinkage can be noticeably improved if the fleece is corrugated, i.e., pleated before being fed to the processing medium and if the continuous random web is guided freely before being pleated over a distance that is substantially equal to or even larger than the width of the untreated fleece. If the free distance between the pair of inlet rollers and the pleating unit is too short, the holding effect of the inlet rollers will adversely effect the uniformity of shrinkage. Only if the distance is equal to or larger than the width of the untreated fleece do the inlet rollers no longer affect the pleating process in any adverse way.

Furthermore, it is also desirable to guide the continuous random web freely through the processing medium, especially if this medium is a liquor, at least until the material is heated-up to the fixing and/or respective shrinking temperature. The appropriate apparatus for achieving this result should comprise a container for the processing medium and guiding elements for the transport of the felt through the processing medium, as well as an inlet unit permitting the variation in the overfeed both in the width and in the length. It is particularly advantageous if the inlet unit comprises two pairs of rollers, the second pair of said rollers -- viewed in the direction of material passage -- being provided with engaging disks or toroids, and if the distance between these two pairs of rollers is equal to or larger than the width of the untreated fleece. Especially with a shrinking bowl, it is of advantage to install the two pairs of rollers vertically or almost vertically above one another.

The device for the desired overfeeding in the width, i.e., the device consisting of a pair of sectional rollers with toroids or slip-on disks, has already been suggested. It has been found that particularly with very large fleeces and wet fleeces above all, that said fleeces are exposed to such a strong frictional force while they pass through the slit of the sectional rollers, that the wave-formation is rather uneven. As a result the outer portions of the material length cannot keep up with the shrinkage in width, i.e., the fleece becomes thinner in the middle and near the middle, and also that the fleece becomes thinner at the points of maximum distortion, i.e., at each "wave crest" because the material which is fed from the sides during the wave-formation, does not suffice. All of this adversely effects the subsequent shrinking process and the uniformity of the produced felt because the unequal density of the untreated fleece results in a corresponding unequal density of the produced felt.

In order to achieve a uniform shrinking it is therefore suggested to start pleating in the middle of the material length, viewed in the direction of material passage, and to allow the two side portions of the fleece to keep up with the shrinkage in width by leaving them without any pressure. The center pleat is then preserved while the two side portions of the fleece are provided with one further pleat each. In this case, too, the remaining side portions can keep up with the shrinkage in width. This is continued until the material length is pleated over its entire width. Thus the material width then corresponds to exactly or almost exactly to the width which the fleece is to have after shrinkage. The overfeeding in width of a fleece to be shrunk, according to the present invention ensures that, if the ratio of overfeed in width is exact, each portion of the untreated fleece can shrink tensionless during the subsequent shrinking process. Thus a felt is produced which has a uniformity and a density unattained up to now.

The process according to the present invention is also advantageous for the shrinking of hosiery and knitted goods as well as of special fabrics such as fabrics of texturized man-made synthetic fibers (e.g. Helanca). One form of construction of the apparatus for carrying out the present process includes a feeding unit which is installed at the feed end of a sieve drum apparatus containing at least one sieve, preferably one sieve drum means which is subject to suction draft. The feeding unit makes it possible to vary the overfeed in length of the material to be shrunk and to overfeed in width progressively from the middle of the material length towards the edges.

Here it is imaginable that the fabric is formed wave-like by means of several pairs of rollers which have a greater number of disks or toroids in the middle than at the sides. The space which is free of disks or toroids has to safeguard the wave-formation of the material without any diagonal distortion of the material.

Another form of construction of the present invention provides for a feeding in the width by means of cylinders which are arranged above and beneath the material length and provided with disks or toroids for the formation of the material length, the further transport of the already wave-like formed material length being safeguarded by means of stationary or moveable guiding elements which are profilated accordingly. The degree of the profilation should be chosen in accordance with the respective product.

A third form of construction provides for an overfeeding in width by the sole means of two guiding elements which are installed at a certain predetermined distance from each other and are either stationary or moveable in the direction of material passage, through which the material length is led. These guiding elements are provided with a corrugated profilation which, as viewed in the direction of material passage, is more pronounced in the middle than it is at the sides of the guiding elements.

If the material is shrunk by means of hot water instead of hot air or hot steam, it is expedient to arrange the pleating rollers together with the preceding feed rollers vertically above one another, or to arrange the stationary or moveable guiding elements between which the material is shaped wave-like, vertically above one another.

The pleating unit is preferably arranged directly in front of the bowl in which the main shrinking of the material is effected. It has been found that the fleece to be shrunk should dwell in the processing medium for about 30 seconds if an absolutely uniform shrinkage is to be achieved. If the temperatures in the first bowl are so high that the material is completely shrunk in said bowl, it is expedient to install the pleating unit at the feed end of the first wash bowl. If, however, the first few bowls serve only for washing-out or rinsing the textile material and if the material is shrunk in the last bowl, the pleating unit is arranged in front of the last bowl.

In order to obtain an appropriate dwelling time and to smooth the felt at the same time, it is suggested to lead the felt over several rollers through the processing medium, especially if this medium is a treatment liquor. At least one of these rollers should be permeable, e.g., perforated and subject to suction draft, that is penetrated by the processing medium from the outside to the inside thereof. This form of construction of the device is particularly advantageous if the pleating unit for the overfeeding in the width is at the same time provided with guiding elements for the variable overfeeding in length.

As shrinkage of the fleece differs depending on the proportion and the type of shrinking fibers contained in the fleece, it is advantageous to mount the first guiding rollers so that they are vertically displaceable with said textile material and to make use of this vertically displaceable motion for the automatic control of the differential speed between the inlet, that is, the pleating rollers and the rollers which are installed in the medium container.

If the shrinking medium is hot air, that is, hot steam instead of hot water, it is advantageous to use a device with a heat-insulated housing in which at least one sieve drum which is subject to a suction draft and possibly an additional sieve drum which serves as the inlet drum, are accommodated. In such a device the sieve drum, that is, the perforated inlet drum is to be preceded by a pair of pleating rollers which are in their turn preceded by a conveyor belt instead of by another pair of rollers.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood by reference to the accompanying drawings which are given by way of illustration only and are not limitative of the present invention and wherein:

FIG. 1 shows a longitudinal section of a shrinking bowl;

FIG. 2 shows the same shrinking bowl as FIG. 1 but viewed from above;

FIG. 3 shows a longitudinal section of another shrinking bowl;

FIG. 4 shows the shrinking bowl according to FIG. 3, with another type of pleating unit;

FIG. 5 shows the pleating unit according to FIG. 4 viewed from the front side;

FIG. 6 shows a longitudinal section of a fixing apparatus operating with hot air, that is, hot steam;

FIGS. 7, 8 and 9 show different embodiments of pleating rollers employed by the subject invention;

FIG. 10 shows the arrangement of the forming elements of the pleating means which are in the form of slide projections;

FIG. 11 shows a construction of the pleating means wherein guiding elements are provided subsequent to the forming elements; and

FIG. 12 shows an embodiment similar to that shown in FIG. 11 wherein the forming elements are rotatable and the guiding elements are stationary.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The apparatus shown in the drawings 1 to 3 consist of a housing 1 which is filled with a treatment liquor and in which sieve drums 2 are accommodated. On thse sieve drums the fleece is heated up shock-like by means of the processing medium which is drawn through the material. The feeding unit comprises a pair of drawing-in rollers 3 and a pair of pleating rollers 4. In this case the free space between the two pairs of rollers 3 and 4 is larger than the width of the untreated fleece 5.

A squeezing unit 6 is disposed at the outlet end of the apparatus. The squeezing unit 6 is preceded by guiding rollers 7 and by vertically displaceable roller 8. The pair of pleating rollers 4 is provided with adjustable slip-on disks 9 which are adapted to engage each other. It is desirable if the disks in the middle of the rollers are installed at a shorter distance from each other than those at the sides. However, it is also possible to vary the diameter of the disks, i.e., to arrange disks with larger diameters in the middle and disks with smaller diameters at the two sides The pleating rollers can also be provided with turned toroids instead of the disks 9. In the apparatus shown in FIGS. 1 and 2, the sieve drum sides are open so that the liquor that flows into the sieve drum can flow into two side compartments 10 from where it is pumped back into the bowl by means of pumps (which are not shown in the drawing) and flange-mounted pump motors 11.

The bowl shown in FIG. 3 is of a similar design as the bowl shown in FIGS. 1 and 2. In this case, however, the free shrinking distance 12 is longer and there is a subsequent vertically displaceable guiding roller 13, the vertical motion of which can be used for the control of the differential speed between the pair of pleating rollers 4 and the sieve drum 2. Thus, the speed difference depends on the degree of shrinkage of the felt.

In order to prolong the free shrinking distance 12, the section of the container 1 which is to accommodate the sieve drum 2 is mounted in a frame 14.

In the form of construction according to FIG. 4 the pleating unit consists of the four pairs of rollers, 21-25 with slip-on disks. As shown in FIG. 5, the disks of the pair of rollers 21 are only provided at the middle of the shrinking-bowl feed end, the discs of rollers 25 are provided over the whole width of the fleece which is at this point already fully corrugated.

The form of construction according to FIG. 6 is provided with a heat-insulated housing 15 in which suction sieve drums 16 are accommodated. At the feed end there is an inlet sieve drum 17 which is preceded by the pair of pleating rollers 4.

In this device the pleating rollers 4 are preceded by a conveyor belt 18 instead of a pair of intake rollers. By means of this pair of pleating rollers 4 the untreated fleece is overfed in width to the sieve drum 17. Overfeeding in length is safeguarded by the speed difference that prevails between the sieve drum 17 and the subsequent sieve drum 16.

The sieve drums 16 and 17 are subject to suction draft. The drum section which is not covered by the material is screened against the suction draft by mean of a stationary baffle plate 19 which is installed in the drum interior. At the outlet end of the device there is installed a roller 20.

FIGS. 7, 8 and 9 show different arrangements of the slip-on disks 9. In FIG. 7, the disks 9 are arranged closer together at the center of the roller core 4' and in FIG. 8, the disks at the center have larger diameters. Disks with varying diameters are shown in FIG. 9.

FIG. 10 illustrates pleating means including a plurality of slide projections 26 which are supported on each side of the textile material to be pleated.

In FIGS. 11 and 12 there are shown those embodiments of the pleating unit wherein guiding elements are provided after the forming elements. In FIG. 11, guiding elements 27 are movable in the direction of material support and in FIG. 12 the guiding elements 28 are stationary.

The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included herein.

Claims

I claim:

1. A process for the production of webs of textile material by shrinking a continuous random web of textile material on a sieve means through which a heated fluid processing medium is passed, which comprises drawing-in the web of textile material to be treated, freely guiding the web of textile material over a distance which is at least equal to the width of the untreated web of textile material and which is substantially vertical, pleating the width of the web of textile material to form a wave-like random web, conveying the pleated wave-like random web to the conveying surface of at least one sieve means, passing a heated fluid processing medium through said conveying surface and through said random web, said web being drawn in at a rate sufficient to provide overfeeding in the length of the random web to the conveying surface of said sieve means, and thereafter removing the random web from the conveying surface of said sieve means.

2. The process of claim 1, wherein the processing medium is a fluid selected from the group consisting of a treatment liquor and a gas.

3. The process of claim 1, wherein the sieve means is in a treatment chamber containing said processing medium and the continuous random web is fed through the processing medium at least until the web is heated up to the shrinking temperature.

4. The process of claim 1, wherein the random web is formed wave-like from the middle of the untreated web towards the outer edges thereof, as viewed in the direction of travel of the web before entering the processing medium for the shrinking stage of the process.

5. The process of claim 1, wherein the web of textile material to be treated is drawn in by roller means, and then freely guided to pleating means for providing overfeeding in the width of the web of textile material, said roller means being disposed substantially vertically above said pleating means.

6. The process of claim 1, wherein the sieve means includes at least one sieve drum means subjected to a suction draft and said processing medium is drawn through said random web.

7. The process of claim 1, wherein said web is composed of at least two fiber types, one of said fiber types shrinking more under the influence of heat than the other.

8. The process of claim 1, wherein said sieve means is immersed in a treatment chamber containing a liquid processing medium and the random web is passed through the liquid processing medium to the conveying surface of said sieve means.