US3494718A

US3494718A - Process and apparatus for dyeing wool and other textile fibres

Info

Publication number: US3494718A
Application number: US493626A
Authority: US
Inventors: Bruce W Wilson
Original assignee: Commonwealth Scientific and Industrial Research Organization CSIRO
Current assignee: Commonwealth Scientific and Industrial Research Organization CSIRO
Priority date: 1964-10-09
Filing date: 1965-10-07
Publication date: 1970-02-10
Anticipated expiration: 1987-02-10
Also published as: GB1088950A; DE1460389A1; FR1450065A

Description

Feb. 10, 1970 a, w. WILSON PROCESS AND APPARATUS FOR DYEING WOOL AND Filed 00%. 7, 1965 OTHER TEXTILE FIBRES 2 Sheets-Sheet 1 INVENTOR BRUCE WARD WILSON ATTORNEYS -2 Sheets-Sheet 2 INVENTOR 'EJRUCEWARDWILSON B. W. WILSON PROCESS AND APPARATUS FOR DYEING wooL AND OTHER TEXTILE FIBRES ATTGRNEYS Feb. 10, 1970 Filed Oct. 7. 1965 United States Patent-O 3,494,718 PROCESS AND APPARATUS FOR DYEING WOOL AND OTHER TEXTILE FIBRES Bruce W. Wilson, Brighton, Victoria, Australia, assignor to Commonwealth Scientific and Industrial Research Organization, East Melbourne, Victoria, Australia, a body corporate Fiied Oct. 7, 1965, Ser. No. 493,626 Claims priority, application Australia, Oct. 9, 1964, 50,311/64 Int. Cl. D06p 3/14 US. Cl. 854 7 Claims ABSTRACT OF THE DISCLOSURE This invention relates to an improved process for the dyeing of wool and other textile fibres, and to apparatus for carrying out such a process. More particularly this invention is concerned with a process for the continuous.

dyeing of wool or other textile fibres, employing a dyebath in which the dye is dissolved in formic acid.

The basic prinicples involved in the use of formic acid as a dye solvent for W001 dyeing are described in Australian Patent No. 238,540 which demonstrates that wool may be very satisfactorily dyed by immersing the wool for a short period in a solution of a dyestuff in formic acid containing up to 30% of water, followed by washing with formic acid .(or a solution thereof) and then with water.

The uptake of dye by wool from a formic acid dye bath is very rapid and is complete in a matter of minutes, at the most. Furthermore, the action of formic acid on wool brings about marked changes in its physical properties; the wool loses all of its natural springiness, a certain amount of swelling takes place and a body of wool so treated becomes somewhat jelly-like in its form and behaviour. Thus the dyeing of wool on a large scale by the use of formic acid dye solutions presents a number of problems in relation to the handling and subsequent treatment of the wool which necessitated the development of the special techniques and apparatus which form a part of this invention.=

In overcoming these problems, it is also possible to actually gain some advantage from their existence and introduce new and useful techniques not previously known to the dyeing art-Other fibres, such as silk, which behave in a similar manner in formic acid can also be dyed usin I concerned with a process "ice press some of the liquor from the fibres to adjust the liquor to fibre ratio to between 2:1 and 6: 1, feeding the impregnated fibres to a conveyor, allowing the fibres to remain on the conveyor for a period sufiicient to allow the desired dye uptake to occur, expressing spent dye liquor from the fibres, and washing and drying the dyed fibres.

For wool dyeing, the preferred concentration of the formic acid is between 70% and 80% by Weight and the dyeing is carried out at a temperature between 40 and 80 C.

Preferably, the fibres are washed in a series of formic acid baths of deer ing acid concentration and finally in water or dilute alkali. Formic acid baths of 15%, 5% and 1.5% concentrations are particularly suitable.

More particularly, the invention provides a continuous process for the dyeing of wool, comprising the steps of impregnating a continuous sliver of the wool with a dyeing liquor comprising a solution of a dyestutf in 70% to 80% formic acid at a temperature between 40 and 80 C., such that the liquor to wool ratio is greater than 6: 1, nipping the impregnated wool sliver to express some of the liquor from the wool to reduce the liquor to wool ratio to between 2:1 and 6:1 by weight, overfeeding the im pregnated fibres t0 a conveyor, allowing the impregnated fibres to remain on the conveyor for a period suflicient to allow the desired dye uptake to occur, expressing spent liquor from the wool and washing the dyed wool in a series of formic acid baths of decreasing acid concentration and finally in a neutral or alkaline water bath and drying the dyed wool.

Preferablythe dyeing liquor has a formic acid concentration of 75-76.'5%, and a temperature between 60 and 80 C. Preferably also the liquor to wool ratio is about 4:1 to 4.521 by weight.

It is further preferred that the wool is first saturated with the dyeing liquor and then the liquor to wool ratio is reduced to the desired range by squeezing or wringing the wool to express some of the liquor from the wool.

The invention also includes apparatus for carrying out the above process and thus according to this aspect of the invention there is provided apparatus for the continuous dyeing of wool or other textile fibres with a formic acid dye liquor, comprising a device for impregnating the fibres with the dye liquor, means for conveying a continuous sliver of fibres through the impregnating device, means for squeezing the impregnated fibres emerging from the device to reduce the liquor to fibre ratio to a desired range,v

a conveyor to hold the impergnated fibres for a period sufficient to allow the desired dye uptake to occur, means for squeezing the fibres to remove the spent liquor from the fibres and means for washing the dyed fibres. The device for impregnating .the fibre sliver with dye or wash liquors is preferably a spray device but may also take the form of a bath or trough through which the sliver passes, or a combination of such devices. I

The means for washing the dyed fibers may be any suitable known textile washing machinery but preferably consists of one or more. stages in each of which the fibre sliver is first saturated with a wash. liquor by immersion.

and then squeezed or wrung to express the wash liquor from the fibres.

The first-mentioned means for squeezing the fibres in the dyeing apparatus preferably comprise a pair of pinch rollers, the clearance *bet ween which is adjustable to permit control of the liquor to fibre ratio of the impregnated fibre leaving the pinch.

In order that the invention may be more fully understood a-specific preferred embodiment of an apparatus for dyeing continuous slivers of carded or combed wool and the preferred apparatus for washing such dyed wool will now be described, with reference to the accompanying drawings in which:

FIGURE 1 is a sectioned elevation of the dyeing section of the apparatus;

FIGURE 2 is a detailed cross-section of the spraying device; and

FIGURE 3 is a front elevation of the washing section of the apparatus.

The apparatus is housed in a chamber 1. The wool sliver 2 is fed into the apparatus by a pair of feed rollers 3 which grip and feed the sliver through an opening 4 in the chamber wall to a spraying device 6, which is shown in detail in FIGURE 2. and comprises an outer casing 7 and an inner sleeve 8, the walls of which are pierced by a number of perforations 10. The sleeve 8 is sealed to the outer casing 7 by means of O-rings 9, and has a waisted central section which provides an annular chamber 11 between the casing 7 and the sleeve 8. The chamber 11 is supplied with a formic acid dyesolution via the pipe 12 from a supply pump (not shown) which draws the dye solution from a heated storage tank (also not shown). The solution emerges from the perforations 10 in the sleeve 8 as a series of fine jets. On emerging from the spraying device 6 the silver passes between a pair of pinch rollers 13a, 13b, the clearance between the pinch rollers being adjustable so that the ratio of dyeing liquor to wool in' the wool leaving the pinch can be adjusted to the desired range, i.e. preferably between 2:1 and 6:1. Excess dye solution and overspray are collected in a tray 14 situated below the spraying device and the lower pinch roller and returned to the storage tank via the pipe.

16. Because of the high rate of circulation of the dye solution and the large volume of the solution carried over by the wool there is no tendency for the dyeing fault known as tailing*in this system.

After leaving the upper pinch roller 13a the wet sliver passes unsupported to an idler roller 17, over this roller, and drops on to one end of a conveyor belt 18. The length and speed of the belt and the feed rate of the sliver are adjusted so that the wool remains on the belt for a period suflicient to allow the desired dye uptake by the wool. The length of the belt required is comparatively short as the wet wool is no longer elastic but is in fact in the form of a limp, almost jelly-like ribbon which readily stacks up concertina-fashion on the belt and occupies a very much smaller volume than would be taken up by wool wetted with water. For example, with a sliver running on to the belt at 1.25 ft./sec., and the belt moving at ft./min., 150 feet of sliver can be accommodated on a foot belt for a period of 2 minutes. This period is generally sufiicient to ensure a 95-100% reaction of the wool with most commercial dyestuffs.

The wool sliver is picked up from the other end of the belt 18 by a further idler roller 19 and passes to a second pair of pinch rollers 21a, 21b, which express most of the residual dye solution from the sliver. The sliver then passes from the pinch roller over another idler roller 22 and out of the dyeing section of the apparatus through another opening 25 in the wall of the chamber 1 and thence to the washing section. A trough 23 beneath the lower second pinch roller receives the spent formic acid dye solution from the second pair of pinch rollers 21a, 21b. The floor 24 of the chamber 1 slopes downwardly towards the exit end'of the apparatus so that any extraneous dye liquor which drains from the belt 18 or other parts of the apparatus can be collected through a drain 26 and recovered. The spent solution and drainings which usually contains a small amount of the dyestutf together with oil and dirt from the wool, are recovered by batch distillation in a glass-lined kettle (not shown).

In the preferred embodiment of the apparatus, the sliver then passes through a series of washing stages which are mostly suitably carried out in the apparatus which is illustrated in FIGURE 3.

In this apparatus, which is also enclosed in a chamber 29, the dyed wool sliver 2 emerging from the dyeing apparatus (FIGURE 1) enters the chamber 29 through an opening 30 and passes over an idler roller 31 then around the lower roller (32b) of and between a pair of feed rollers 32a, 32b. The lower roller (32b) is partially immersed in a trough 33 which contains a wash liquor, most suitably a formic acid solution of about 15% concentration. The dyed sliver 2 which is thus saturated with the wash liquorfrom the trough 33, then passes through a pair of pinch rollers 34a, 34b, which express the major part of the formic acid wash liquor from the sliver, together with any residual dye solution remaining from the dyeing process. The liquor thus expressed from the wool is collected in a trough 35 situated beneath the lower pinch roller 34b, and passes, via the pipe 36, to the formic acid recovery section of the dyeing apparatus.

From the pinch rollers 34a, 34b, the sliver passes over an idler roller 37, and thence to a further pair of feed rollers 38a, 38b, the sliver passing first under the lower roller 38b, which is partially immersed in a trough 39, containing a further wash liquor, desirably a formic acid solution of about 5% concentration. The sliver now saturated with the acid passes over an idler roller 41 to a further pair of

pinch rollers

42a, 42b, which again express the acid from the sliver. The acid thus expressed, which now has a concentration of about 15%, is collected in a trough 43 from which it passes by gravity through the pipe 44 to the trough 33 to be used in the first washing stage.

'From the

pinch rollers

42a, 42b, the sliver passes to a further washing stage involving idler roller 45, a further pair of feed rollers 46a, 46b, and a trough 47. The wash liquor for this stage is formic acid and of about 1.5% concentration.

-It is desirable at this stage to provide a short holding period for the saturated sliver to ensure complete removal of any residual dye liquor and this holding is provided by passing the sliver around a series of idler rollers 48, 49, 51, before passing the sliver to the next pair of pinch rollers 52a, 52b, whereby the acid is expressed from the wool (at a concentration now of about 5%) collected in the trough '53, and passed through the pipe 54 to the trough 39.

The sliver passes from the pinch rollers 52a, 52b, over a further idler roller 55, to the last washing stage involving feed rollers 56a, 56b and trough 57, a holding stage involving idler rollers '58, 59, 61, 62, 63, pinch rollers 64a, 64b and trough 65. The trough 57 is fed with hot water and formic acid at about 1.5 concentration is col- I lected in trough 65 and passed to trough 47. The sliver then passes out of the washing apparatus through a further opening 66 in the chamber wall to be dried and gilled in the conventional manner.

The chambers 1 and 30 are totally enclosed except for the openings 4 and 25, 30 and 66 respectively. The chambers are constructed of or are lined with an acidresistant material, a suitable material being polypropylene. The various rollers, troughs, pipes and other parts of the apparatus which are contacted by the formic acid or its vapours are also fabricated from or covered with acid-resistant plastics materials, rubber or acid-resistant metals.

Vent pipes 27 and 67 are provided in the roofs of the chambers 1 and 30 respectively and are connected to an exhaust system (not shown) so that a slight negative pressure (with respect to atmospheric pressure) is maintained within the two chambers to remove acid vapours from the chambers and-to minimise any leakage of such vapours to the atmosphere outside the chambers which by weight of formic acid. This acid is fractionated in a glass distillation column. 1.5 percent acid is obtained from the top of the column leaving residual acid in the boiler containing 73-74% by weight formic acid. The strong acid is redistilled from a glass lined kettle and made up to 75% by the addition of commercial 90% acid before being returned to the dyeing cabinet. Losses from the distillation column and acid lost in the wool drier are small and are made up by the above addition of 90% formic acid. The 1.5% acid from the top of the column is utilized in the last acid-washing step.

In a typical production run, 3.38 kg. (7.47 lb.) of type 64 wool tops was dyed to a shading of 3% with the reactive dyestuff Drimarene Red Z-RL, according to the following procedure:

Drimarene Red Z-RL 146 g. (0.66 lb.) was pasted in a small amount of cold water and then dissolved in hot water to make a solution containing 3.56 kg. (7.75 lb.) of water. This solution was mixed with 18.12 kg. (40 lb.) of 90% formic acid to make a dyeing solution of the dyestutf in 75 w./w. percent formic acid.

The dye solution was pumped to the storage tank located on the dyeing apparatus described above, and the temperature of the solution was raised to and maintained at 65-70 C. by circulating the dye solution through a glass coiled heat exchanger. All pipe-lines were made of polyethylene and the circulating pump was constructed of polytetrafiuoroethylene (Teflon).

The dyeing apparatus was loaded with Wool sliver by drawing the sliver through the spraying device and the roller system wtih a fibreglass tape. With the apparatus in motion, the preheated dye solution was pumped to the spraying device and the wool was thus saturated with the formic acid dye solution.

After leaving the spraying device the sliver passed through the pinch rollers 13a, 13 which were adjusted to a clearance of 0.060 to 0.064 inch.

The sliver then passed to the conveyor belt 18 and remained there for two minutes, after which it was then picked up by the idler roller 19 and the second set of pinch rollers 21a, 21b, and the excess 75% formic acid solution squeezed out. By this time 98% of the dye had reacted with the wool sliver and the solution contained very little visible colour. The weight of the wet wool after squeezing was 8.66 kg. (19.11 lb.) and the weight of acid removed by squeezing 10.48 kg. (23.13 1b.).

The wool was then washed in the apparatus described above and washed successively in this manner with solutions containing 15, and 1.5% formic acid and finally washed with water. The time taken for each washing was two minutes and the temperature of the wash solutions was 6070 C. The washed wool was dried without further treatment.

The recovered acid (i.e. 73% formic acid) was mixed with a small amount of 90% acid and a 75 solution was thus prepared for use in further dyeings.

Wool dyed as described above has a softer feel than wool dyed by conventional methods but is in no way damaged by the formic acid solutions used under the conditions described above. The percentage noils on subsequent processing of the dyed wool is approximately the same as for conventionally dyed wool.

No special types of dye are necessary and most commercially available dyestuffs can be used. It has been found that the best results are obtained with the reactive dyestuffs, acid milling dyestuffs and acid levelling dyestuffs. Chrome blacks can be produced by adding the chrome to the dilute washing stages after dyeing (e.g. at the 1.5 acid washing stage). 1:1 premetallised dyestuffs can also be used but 1:2 premetallised dyestuffs are not favoured for use in the method of the invention.

I claim:

1. A continuous process for the dyeing of wool or other textile fibres comprising the steps of impregnating a continuous sliver of the fibres with a dyeing liquor at 40-80 C. comprising a solution of a dye-stuif in -80% by weight formic acid, nipping the impregnated fibre sliver to express some of the liquor from the fibres to adjust the liquor to fibre ratio to between 2:1 and 6: 1, feeding the impregnated fibres to a conveyor, holding the fibres on the conveyor for a period sufiicient to allow the desired dye uptake to occur, expressing only a portion of the spent dye liquor from the fibres, and washing and drying the dyed fibres.

2. A process as claimed in claim 1, wherein the concentration is from to 76.5% by weight.

3. A process as claimed in claim 1, wherein the temperature is between 60 C. and C.

4. A process as claimed in claim 1, wherein the liquor to fibre ratio is about 4:1 to 4.5 :1 by weight.

5. A process as claimed in claim 1, wherein the dyed fibres are washed in a series of formic acid baths of decreasing concentration and finally in water or dilute a1- kali.

6. A process as claimed in claim 5, wherein three formic acid baths are used successively, the concentrations of the baths being about 15%, 5% and 1.5% respectively.

7. A continuous process for the dyeing of wool comprising the steps of impregnating a continuous sliver of the wool with a dyeing liquor at 4080 C. comprising a solution of a dyestuff in 70-80% by weight formic acid, nipping the impregnated wool to express some of the liqnor from the fibres to adjust the liquor to fibre ratio to between 2:1 and 6:1, feeding the impregnated wool to a conveyor, holding the wool on the conveyor for a period suflicient to allow the desired dye uptake to occur, expressing only a portion of the spent dye liquor from the wool, and washing and drying the dyed wool.

References Cited UNITED STATES PATENTS 2,460,206 1/ 1949 Wentz 6822 3,314,256 4/1967 Walsh et a1 6822 3,364,705 1/1968 Thornber 68--22 OTHER REFERENCES Lemin, 1 our. Soc. Dye. & Colour., 74, November 1958, pp. 746, 747, 754.

NORMAN G. TORCHIN, Primary Examiner I. E. CALLAGHAN, Assistant Examiner US. Cl. X.R. 8-22, 55