IL23462A - Treatment of wool materials - Google Patents

Description

C O H E N Z E D E & S P I S B A C H E G D . PAT E NT ATTO RN EYS 24, LEVONTIN SIR., P. O. B. 1109 T E L - A V I V P A T E N T S ά D E S I G N S O R D I N A N C E 13182/65 SPECIFICATION WOOL TREATMENT OF ?Β5«¾¾& MATERIALS ias '-|»ΤΠ3 lSPD This invention relates to improvements in the treatment of wool to impart shrink resistance thereto and is more especially concerned witb the treatment of materials consisting of or containing wool which are available in continuous form, or which can readily be joined together into a continuous form to enable the same to be subjected to substantially uniform treatment.

Woollen materials which are available in continuous form include yarns, tops and woven and knitted fabrics consisting of or containing wool.JSe¾engths wfaAob-oorvo -as-a—Qjsa.tiftu©«e—fe-apa may also be formed by sewing together knitted garments such as socks: these are then separated after completion of the treatment.

Frocesses are known for the treatment of wool to impart shrink resistance thereto which involve the application of two distinct chemical reagents to the wool.

As a rule these may be applied either simultaneously or successively. One difficulty which arises in simultaneous treatment is due to the fact that different chemical re-agents almost invariably react with wool at different rates.

This need not give rise to undue difficulty in batch proof length cessing, but in continuous processie^/cTifficulties arise.

It is an object of the present invention to provide an improved continuous process for imparting shrink re-sistance to wool in a continuous form in which the wool is simultaneously treated with a plurality of chemical markedly reagents which react therewith at/different rates.

According to the present invention there is provided a process for imparting shrink resistance to wool and length a continuous of such a material with an aqueous liquor containing (a) a wetting agent and (b) at least two shrink-resistance-imparting oxidising agents for wool which react with woollen fibres at different rates and which together produce a shrine-resistant effect thereon, sub,st-¾¾¾^L-y immediately after wetting-out passing the wetted-out material through the nip between a pair of rollers so as to ensure that the material is uniformly impregnated with a controlled amount of said liquor and maintaining said controlled amount of liquor in contact with said material until at least a desired amount of each of said chemical reagents has reacted with the wool with which it is in contact.

According to a feature of the invention metered quantities of aqueous solutions of each of said oxidising and said wetting agents agents/are fed into said aqueous liquor to maintain the desired composition thereof, which quantities are correlated with the rate of pickup of liquor by woollen materials undergoing treatment so that (a) the volume of liquor remains substantially constant and (b) complete renewal of liquor takes place in 1 to 15 minutes.

The invention may be performed in various ways and employing various reagents.

One reagent system to which the invention is applic-able is an aqueous solution containing an alkali metal permanganate, e.g. potassium permanganate and an alkali metal or calcium hypochlorite at pH values between 5 and 10.

In this system the hypochlorite reacts much more with wool than the permanganate. Thus, much longer contact than is required for the hypochlorite to react.

Another reagent system to which the invention is applicable is an aqueous solution containing permonosul-phuric acid and an alkali metal dichloroisocyanurate, e.g. sodium or potassium dichloroisocyanurate. At pH values below 5, e.g. 2.0 to 4.0, which are encountered with such systems the dichloroisocyanurate reacts with the wool at a much more rapid rate than the permonosulphuric acid.

The use of the dichloroisocyanurate at the indicated pH values has, moreover, the advantage that the characteristic yellowing of wool associated with its use at higher pH values is avoided.

Other reagent systems to which the invention is applicable are (a) an aqueous solution containing permonosulphuric an alkali metal hypochlorite, e.g. acid and/sodium or potassium hypochlorite and (b) the system containing peracetic acid and sodium or potassium hypochlorite.

The passage of a continuous wool through a large volume immersion bath containing one of the above systems is attended by unpredictable results. The first portion of the wool undergoing treatment will be vigorously attacked by the more rapidly reacting reagent and subsequent portions will be less severely attacked as the concentration decreases. The change in the concentration of the slower acting reagent will be more gradual. However, it is clear that the shrink-resistance imparted to the wool by such a bath in continuous use will be quite unpredictable.

Whilst it is theoretically possible to maintain the concentrations of the reagents at desired values, this, in practice, has not proved feasible in a system of this kind.

The present invention seeks to overcome difficulties of the kind outlined above by supplying to each increment of material a controlled amount of treating liquor containing regulated amounts of each of the reagents and maintaining this controlled amount of liquor in contact with that increment of material until a predetermined proportion, or the whole, of each of the reagents has reacted therewith. In this way a much more closely controlled shrink resistance can be applied in continuous operation than has hitherto been possible with such systems.

In carrying out the process of the present invention reservoirs containing aqueous solutions of each of the two reagents are first prepared. Either or both of these solutions .¾a^ also contain a wetting agent. Whilst any kind of wetting agent may be used an anionic or a non-ionic wetting agent is preferred. These two solutions in metered quantities are admixed only shortly prior to application to the woollen material undergoing treatment.

In one form of the invention the woollen material is supplied with a controlled amount of treating liquor by passage through a bath of small capacity which receives liquor from the reservoirs referred to above. The wetted' out material is then between the nip of a' pair of precision rollers located adjoining the exit from the bath. The nip at the rollers is so adjusted as to ensure that the woollen material passing therethrough retains within its interstices a volume of treating liquor containing an amount of the treating reagents which is sufficient to impart to the After passing through the precision nip the liquor-containing goods are run forward over and under rollers or on a brattice or scray or otherwise retained in contact with the liquor for a time sufficient to allow the whole of both reagents, or at least a predetermined proportion of each which will suffice to impart the desired degree of shrink resistance, to react. The pick-up of aqueous liquor at the nip may be 50-250% of the weight of the wool the preferred pick-up is 100-1 50%.

It should be noted that the time of residence or immersion in the bath is ^uh^fnnti nl 1 only sufficient to ensure that the goods are fully wetted out by the aqueous liquor in the bath. A preferred time -?e-g--¾ roi4cnc¾ or secconds.

This is sufficient time to ensure thorough penetration and wetting-out of the wool but is insufficient to allow any significant exhaustion of the liquor in the bath. The concentration of the liquor remains at virtually the same concentration as that of the liquor fed into the bath.

A bath having a capacity of 1 to 2 gallons of liquid is contemplated although smaller and somewhat larger baths may be used if the circumstances, such as the rate of removal of liquor from the bath, require, It is a feature of the invention that the volume of liquid admitted to the bath is correlated with the rate of pick-up of liquor by the woollen materials passing through the bath so that complete renewal of the bath liquor takes place in a period of 1 to 1 5 minutes: preferably the time for complete 1 to renewal is -looo— tkaa 10 minutes. These times of renewal oxidising agents to occur before coming into contact with the woollen material. Thus, the material as it passes through the bath takes up a controlled amount of virtually fresh, uncontaminated liquor. There is virtually no opportunity for any extraneous substances present in the woollen materials, such as combing oils present in tops, to pass from the materials into the bath and thus accumulate therein. In consequence it is possible to produce a much more closely standardised treated wool having a predictable degree of shrink resistance imparted thereto. Moreover, any adventitious salt present in the contents of either reservoir is carried forward in the interstices of the materials and thus remains a substantially constant factor if it has any influence at all upon the shrink resistance reactions.

It has already been observed that the volume of liquid admitted to the bath is correlated with the rate of pick-up of liquor by the materials passing therethrough. Initially the bath is filled to the desired extent with liquor of the desired composition. The volume of liquor in the bath is then maintained substantially constant throughout substantially the whole of the run by metering fresh solution from each of the reservoirs of oxidising agent into the bath in such proportions as to maintain the composition of the bath substantially constant. Only during the last few minutes of a run should the volume of liquor in the bath be allowed to fall.

In an alternative form of the invention the woollen material is supplied with a controlled amount of treating tank on to both sides of the material. The spraying may be done from a manifold located upon each side of the goods. The tank receives liquor from the reservoirs referred to above and devices are provided for replenishing the contents of the tank from the reservoirs as the liquor is used. Accurate adjustment and uniform distribution of the pick-up is secured by passing the sprayed material between the nip of a pair of rollers in the manner already indicated.

Considering in more detail, as an example of the process, the permonosulphuric acid-alkali metal dichloroiso-cyanurate system, two reservoirs are used, one of which contains an aqueous solution of permonosulphuric acid and ■pajo orably a wetting agent, whilst the other contains sodium or potassium dichloroisocyanurate. The permonosulphuric acid solution may have a pH value of 1.0 to 2.0, whilst that of the dichloroisocyanurate solution is approximately 5, at which pH value it is stable, when the solutions are mixed the resulting solution has a pH value of about 3, and the dichloroisocyanurate is no longer stable. By mixing the solutions as they are required for impregnation the resulting system does not have time to undergo appreciable decomposition before it is applied to woollen material undergoing treatment since the bath or tank should not contain more liquor than is expected to be used in the ensuing 1 to 10 minutes. This mixed solution is rapidly picked up in a measured dose by wool using the above described techniques and then reacts completely or virtually completely with the wool during a dwell period before At the conclusion of the treatment any residual treating agents and reaction products derived therefrom are removed by washing the treated material with water. The wool is then passed through a dilute aqueous solution of a reducing agent such as sodium sulphite or sodium bisulphite in order to complete the shrink-resist treatment. The thus treated material is then again washed with water and finally dried.

In the case of the permonosulphuric acid and alkali metal hypochlorite system two reservoirs are used, one of which contains an aqueous solution of permonosulphuric acid and a wetting agent, whilst the other contains sodium or potassium hypochlorite. The permonosulphuric acid or potassium hydrogen permonosulphate solution which may contain added sulphuric acid, may have a pH value of 0.5 to 2.0, whilst that of the hypochlorite solution is approximately 8.0 to 9.0 at which pH value it is stable, when the solutions are mixed the resulting solution has a pH value of about 3 to 5» according to the ratio in which the solutions are mixed, and the hypochlorite is no longer completely stable. By mixing solutions as they are required for impregnation the resulting system does not have time to undergo appreciable decomposition before it is applied to the woollen material undergoing treatment.

The preferred pE value of the bath is 3.5 to 4.5.

The following examples illustrate the nature of the invention.

EXAMPLE 1 Ten continuous lengths of wool tops, each weighing g. per metre, are passed through a bath having a capacity of 4. 5 litres and filled with a solution containing 1 .77% by weight of potassium hydrogen permonosulphate (which is equivalent in oxidising power to 1 . 33% permonosulphuric the condensation product of trimethylno-acid), 0. 5% by weight of (a non-ionic nylphenol with 6 moles of ethylene oxide wetting agent) and 1 . 33% by weight of sodium dichloroiso-cyanurate; this solution has a pH value of substantially 3.

After passing through the solution the wool enters a precision nip adjusted so that the pick-up of solution is 0% of the weight of the wool. The speed of the wool is 5 metres per minute. Thus 1 kg. of wool passes through the bath and nip each minute, taking away with it 1 . 5 litres of the above treating solution.

The bath is kept full by metering into it a liquor obtained by admixing (i) 50 cc. per minute of 3. 54-% by weight aqueous solution of potassium hydrogen permono- the aforesaid non-ionic wetting sulphate containing 1 % by weight of /S»»gi*^- EMI*- and having agent a pH value of 1 , and (ii) 750 cc. per minute of 2.66% by weight aqueous solution of sodium dichloroisocyanurate having a pH value of 6. These two solutions are stable for long periods and they are only admixed immediately prior to use.

Since the bath has a capacity of 4. 5 litres and the mixture is used up at the rate of 1 . 5 litres per minutes-, the mixture remains in the bath for a period of 3 minutes.

During this 3 minutes the loss in oxidising power is negligible. The dwell time of the wool in the bath is After passing the precision nip the wool is allowed to fall upon a brattice moving at such a speed that the wool remains thereon for 1 . 5 to 2.0 minutes and then passes through the following baths:- (a) rinse bath of water, (b) aqueous 5% sodium sulphite solution at pH 7.2 and (c) two further rinse baths of water. The dwell time in the sodium sulphite bath is 30 seconds. The material is then dried.

Samples of treated and untreated wool tops were submitted to a standard washing test in the Dylan Cubex Machine with the following results:- Untreated control 21% shrinkage; treated material 2% shrinkage.

EXAMPLE 2 Woven and knitted woollen fabrics are treated in the equipment described in Example 1 using a solution containing 1 .33% by weight of potassium permanganate, 1 % by weight of the non-ionic wetting agent used in Example 1 , ¾a^it©X-S -i , sodium hypochlorite to provide 1 .33% by weight of available chlorine and 5% by weight of magnesium sulphate. The pH value of the solution was 9.3. The rate of passage of the fabric through the bath is 1 kg. per minute and the precision nip is set so that the pick-up of solution is 50% of the weight of the wool. The treatment is thus with 2% of the weight of the wool of potassium permanganate and 2% of available chlorine.

The bath is kept full by metering into it a liquor obtained by admixing (i) 750 cc. per minute of a solution containing 2.66% by weight aqueous solution of potassium permanganate and sodium hypochlorite in an amount which yields 2.66% of available chlorine, and (ii) 75^ ccs. per complete replacement of the bath every 3 minutes.

The wool immediately assumes a dark brown colour due to deposition of manganese dioxide. It is allowed to fall on a moving brattice where it remains for 2 minutes, after which time the reaction is substantially complete. The treated wool then passes through the following baths :-(a) rinse bath of water, (b) 3% by weight aqueous sodium bisulphite solution containing 1% of formic acid, and (c) two further rinse baths of water. The dwell time in the sodium bisulphite bath is 25 to 30 seconds. The material is then dried at 80°C.

Samples of treated and untreated fabric were submitted to a standard washing test in the Dylan Gubex Machine with the following results:- Untreated control 28% shrinkage; treated material 5% shrinkage.

EXAMPLE 3 Example 2 was repeated but the concentration of the potassium permanganate-sodium hypochlorite solution was increased so that the wool was treated with 3% of its weight of potassium permanganate and 3% of available chlorine. When submitted to the standard washing test the treated material showed 2% shrinkage.

EXAMPLE 4- Wool is continuously treated in the same manner as described in Example 2 with the modification that the bath is kept full by metering into it a liquor obtained by admixing (i) 750 ccs/min. of a solution containing 2.6% by weight of an aqueous solution of potassium permanganate and sodium hypochlorite in an amount which yields 2.66% Siangan β s © weight aqueous solution of ¾ag¾ooi\¾a- sulphate containing the non-ionic wetting agent used in Exaple 1 2% by weight of ¾e-»gi*-ei— ΦΜΕί and a quantity of sulphuric acid such that when (i) and (ii) are mixed in equal amounts the pH of the thus produced solution is 7.0.

The treated wool when submitted to the standard washing test shows a shrinkage of 2%.

Claims (11)

HAVING NOW particularly described and ascertained the nature of ou said invention and in what manner the same is to be performed, we declare that what we claim is t

1. A process for imparting shrink resistance to wool and wool-containing materials which comprises wetting-out length continuous/ form of such a material with an aqueous liquor containing (a) a wetting agent and (b) at least two shrink-resistance-imparting oxidising agents for wool which react with woollen fibres at different rates which and/together produce a shrink-resistant effect thereon, s- bstaati-aiiy immediately after wetting-out passing the wetted-out material through the nip between a pair of rollers so as to ensure that the material is uniformly impregnated with a controlled amount of said liquor and maintaining said controlled amount of liquor in contact with said material until at least a desired amount of each of said chemical reagents has reacted with the wool with which it is in contact.

2. A process according to claim 1 in which metered quantities of aqueous solutions of each of said oxidising and said wetting agent agents/are fed into said aqueous liquor to maintain the desired composition thereof, which quantities are correlated with the rate of pickup of liquor by woollen materials undergoing treatment so that (a) the volume of liquor remains substantially constant and (b) complete renewal of liquor takes place in 1 to 15 minutes.

3. A process according to claim 2 in which complete renewal of liquor takes place within 1 to 10 minutes.

4. A process according to any of claims 1 to 3 in the material is wetted out b a

5. A process according to any of the preceding claims in which the pickup of liquor at the nip between said rollers is 100 to 150% of the weight of the woollen material.

6. A process according to any of the preceding claims in which one oxidising agent is permonosulphuric acid and the other is an alkali metal dichloroisocyanurate.

7. A process according to any of claims 1 to 5 in which one oxidising agent is permonosulphuric acid and the other is an alkali metal hypochlorite.

8. A process according to any of claims 1 to 5 n which one oxidising agent is an alkali metal permanganate and the other is an alkali metal or calcium hypochlorite and the pH is between 5 and 10.

9. A process according to any of the preceding claims in which the thus treated wool is thereafter treated with a dilute aqueous solution of a reducing agent.

10. A process for imparting shrink resistance to wool, and woollen materials according to claim 1 and substantially as hereinbefore described with reference to any of the Examples.

11. Wool and wool-containingmaterials which have been rendered shrink-resistant by the process of any of the preceding claims. , } '