US3416954A - Process for the durable creasing or other permanent setting of textile materials containing wool or other keratin fibres - Google Patents

Description

United States Patent ABSTRACT OF THE DISCLOSURE Rendering a textile material selected from the group consisting of wool and other keratin fibers heat settable in which the material is impregnated with a solution containing (1) at least one compound which acts as a setting agent by increasing the number of ionized thiol groups in the fibers but not being a reducing agent and (2) at least one compound which acts as a hygroscopic substance having the capacity for increasing the moisture content of the fibers duringheating of the material in a subsequent permanent heating step and drying the material.

This invention relates to treatment of textile materials including yarns and tops composed wholly or partly of wool or other keratin fibres for the purpose of permanent setting, for example creasing or pleating during garment making-up, without the need for applying water or a solution of chemicals immediately prior to carrying out the setting operation, for example steam pressing.

Australian patent specification No. 225,996 describes the currently-accepted mechanism or permanent setting and the currently-accepted definitions of terms such as "permanent setting. "creasing." pleating etc. Such terms are used in the same sense in this description of this present invention which is also based on the same mechanism of permanent settingfAustrnlian pecification No. 225.996 describes a process in which wool textile materials are treated with a solution of reducing agent immediatcly prior to steaming or steam-pressing in the wet state to impart durable pleats or creases and. in particular, shows the essential role of water in permanent setting.

Permanent setting involves rearrangement of both hydrogen bonds and disulphide cross links between the polypeptide chains of the wool molecules. Hydrogen bond rearrangement requires heating in the presence of a hydrogen bond breaking compound of which water is the most common example. Disulphide bond rearrangement requires the presence of free ionized thiol groups attached to molecular side chains -and takes place via an interchange between said disulphide bonds and ionized thiol groups. Thus, one ionized thiol group can initiate the rearrangement of many disulphide bonds. Wool normally contains small numbers of ionized and unionized thiol groups in equilibrium but rapid setting requires the presence of a greater number of such groups than is normally present. Theseare usually produced by the action on the wool of reagents which break disulphide bonds and which hereinafter will be referred to as setting agents. Reducing agents are well known to be effective setting agents because they reduce the disulphide bonds and some of the thiol groups so formed will be ionized. it is perhaps not appreciated that some alkaline compounds also are effective setting agents mainly because they ensure that most of the existing thiol groups will be ionized Patented Dec. 17, 1968 but also because additional thiol groups can be formed by hydrolysis of disulphide bonds each of which would form one ionized thiol group and one sulphenic acid group.

Australian patent specification No. 209,203 relates primarily to permanent setting by steaming in the presence of a volatile alkali or reducing agent, but mentions that a non-volatile reducing agent such as sodium bisulphite, can be used by pretreating the wool fabric in a solution of the agent, followed by rinsing and drying. The dry fabric can then be permanently creased or pleated merely by steam-pressing under the same conditions as those used traditionally for creasing garments. The durability of such creases is. in fact, much less than that of those produced by steaming in the wet state as in Australian specification No. 225,996. Moreover, the use of reductive setting agents in this way causes wool to acquire an objectionable odor and lowers the strength, abrasion, and wrinkle resistance.

If fabric. pretreated according to Australian specification No. 209,203, is dampened with water before steaming, then the reactions are the same as described in Australian specification No. 225,996 and the creases or pleats have the same excellent durability. Such permanent setting is dueto the residual amounts ofthe non-volatile reagent left behind in the pretreated fabric. since pro longed and thorough rinsing removes the ability of the fabric to take a permanent set.

While the presence of water during setting is essential for the necessary. molecular bond rearrangements to take place, it has been found that it is not necessary to add water, as such, provided the wool already contains a substance which causes extra condensation of moisture in the wool particularly during steaming. Such a reagent will hereinafter be referred to as a "hygroscopic substance."

Permanent setting can thus be brought about in wool which is dry to the touch by previously adding compounds which (i) behave as setting agents but which have no reducing power so as to avoid excessive damage to the wool and (2) increase the regain of wool during steaming due to their hydroscopic properties and. preferably. also have a hydrogen bond breaking capacity. This will usually entail the addition of two separate compounds to the wool but, as will be disclosed in the following. a single compound can sometimes be made to fulfill both functions.

The present invention provides a new process for the permanent setting of a textile material consisting of or containing wool or other keratin fibres,'which comprises the steps of. impregnating the material with a solution of a compound or a combination of compoundswhich compound or combination (1) acts as a setting agent by increasing the-number of ionized thiol groups in the wool but is not a reducing agent (2) acts as a hygroscopic substance which increases or has the capacity to increase the moisture content of the wool during heating of the material in a subsequent permanent setting step.

The process of the present invention may be applied to textile yarns or fabrics.

The setting agents for use in the present process are preferably alkaline. Examples of such agents are ammonium or alkali metal salts of carbonic. boric or other weak acids, organic amines and their carbamates or carbonates, quaterrary ammoniumhydroxides or carbonates and other salts of the foregoing bases with weak acids. The organic agents are much more efl'ective for setting and cause less damage to the wool than the inorganic agents.- In addition. the carbarnates and carbonates are colorless hydrophilic organic or inorganic salt, such as sodium chloride, at hydroxyamine salt, or a quaternary ammonium salt, or (2) an Organic humectant such as glycerol, glycol or other polyhydroxy compounds such as the sugars or their derivatives. Preferably, the hygrm scopic substance is a compound which also has hydrogenbond-breaking properties such as urea, urea derivatives and analogues. lithium bromide, or formamide.

The preferred concentration or setting agent is less than 5% on the weight of wool and that of the hygroscopic agent less than Greater quantities can be used but these tend to produce an undesirable stiffening of the fabric.

One preferred combination of chemicals for commercial application is any of the ethanolamines, either mixed or individually, together with urea. Such pretreated fabric needs to be used within 1-2 months.

if a fabric is required to have an indefinite shelf life the carbonates or substituted carbamates should be used instead of the free base. These can be prepared by bubbling carbon dioxide into the amines in, respectively, the 7 presence or absence of water. The carbamatcs start to hydrolyse on mixing with water so there is not much difference whether the starting product is carbonate or carbamate.

The ethanolamines besides being setting agents also have hygroscopic properties, so that the desired effect can be produced by using relatively large quantities (for examle. 5 to of such setting agents alone. However, the use of large quantities of setting agent is to be avoided because of possible damage to the wool and, in any case, it is more economical to add instead a substance such as urea.

On the other hand it is not always necessary to specifically add a setting agent. For example, a fabric containing a large amount of urea can be permanently set when heated to a sufficiently high temperature with a hot iron, superheated steam or steam under pressure to release ammonia (a setting agent) from the urea.

Generally, the amount of moisture present in the fabric during steaming will be lower than that considered optimum for setting according to Australian specification No. 225,996, but in the preferred forms of the invention, this is compensated for by the presence of a hydrogen-bond-breaking agent. Moreover, because of the smaller amount of water, only relatively small amounts of agent are needed to produce a relatively high effective conccntration in the fabric.

One method of application is to pass an otherwise finished, and preferably approximately neutral, fabric through an aqueous solution containing the required amounts of both reagents, through squeeze rollers to re move excess solution followed by drying on a tentcr and, finally, steaming for a short time (Vt- A min.) in a blowing machine. Tentering and blowing are carried out according to normal mill practice without special precautions but it is preferable to avoid overheating on the tentcr, to avoid excessive tension on the cloth and to cool the fabric thoroughly before removal from the blower.

The heating and steaming during tenteringand blowing introduce a certain amount of flat setting, but this does not impair the ability of the fabric to take a permanent crease later. Likewise a moderate amount of pressing flat during making-up does not reduce the effectiveness of the subsequent creasing operation. However, longer steaming (which, in effect, is a setting operation) prior to creasing or pleating can produce a noticeable reduction in the effectiveness of the latter operations, although the durability of such creases or pleats is still acceptable.

Wetting the fabric at any stage prior to the final setting operation does not reduce the effectiveness of the treatment. but if the reagents are washed out, the fabric will no longer take a permanent set, although any set put in before washing will be retained. Water, of course.

could be applied and the fabric steamed in the wet state,

in which case the permanent set would be excellent, but the purpose of this invention is to avoid this inconvenient step.

When pleating fabric pretreated as above, no departures from normal practice are needed. Thus the fab ric may be folded in pleating papers and steamed for about A to 1 hr. at atmospheric pressure or a shorter time under pressure. In general, the time of steaming need only be about half that normally used for untreated fabric. An important advantage of the present invention is that pretreated fabric can be successfully permanently set following machine pleating which is virtually impossible with the wet-type setting treatments.

For creasing of, for example, trousers on the Hoffman press, attention has to be given to the setting and manipulation of the press to obtain optimum results. Hoffman pressing usually removes moisture from a fabric. To realize the full benefits of the present invention, the condi tions of the press should be adjusted to encourage condensation of moisture in the fabric. This can be brought about in the following ways:

(l) Both top and bottom bucks of the press should be well padded to insulate the fabric from the hot metal parts. There is a noticeable reduction in crease durability if the fabric is pressed on a press with an uninsulated metal-plate top buck.

(2) it is desirable to cool first the press padding and then the fabric by vacuuming before steaming. A preliminary steaming for a few seconds followed by vacuum,

as in normal practice to mold the fabric, is advantageous.-

However, vacuuming the fabric in a warm press is to be avoided.

(3) Under a given set of conditions on the press, the amount of water taken up by a fabric is about the same whatever its initial moisture content. Thus, it is advantageous to have the initial moisture content as high as possible i.e. it is preferable for the fabric tobe in an atmosphere of high humidity immediately prior to pressing. The garments should not be stored too close to the press since radiant heat from the press will dry them out even though the humidity in the press room might be high.

ity which the industry now expects, i.e. as obtained using the conditions specified in Australian specification No. 225,996, a total pressing time of about l min. is required. The moisture content of a fabric does not change much after 30 sec. steaming so that for the remaining time the fgiric can be left in the closed press with the steam turned 0 a (5) Providing the foregoing precautions are observed. the steam pressure is not critical. With padded top and bottom bucks cooled by vacuuming before pressing, satisfactory crease durability is obtained with steam pressures between 20 and pfs.i., preferably 40-60 p.s.i. However, with an uninsulated metal-plate top buck. the pressure (i.e. temperature) must be very low. Crease durability is barely satisfactory at 10 p.s.i. and with increasing pressure the durability decreases to zero at 80 p.s.i. Most presses willi not operate satisfactorily at pressures as low as 10 pt.

The pressing conditions become less critical as the concentration of hygroscopic agent is increased; if more than about 15% is used none of the foregoing precautions need to be observed.

- An application of particular interest is the production of stretch fabrics. After applying the reagents by padding or otherwise, the wet fabric is stretched in One direction and allowed to contract in the other, dried while held at the new dimensions and later set by a steaming treatment while held at the new dimensions. The most convenient and easily controlled sequence is to overfeed the warp up to 50% onto the tenter while stretching the weft up to 50%, and dry as usual. The fabric at this stage is quite stable while dry, but if wet or steamed while not held, it will return to its original dimensions and have no stretch properties.

The set may be made permanent by steaming on the blowing machine for about 5 min., and the resulting fabric will have permanent elastic stretch in the warp, the

amount being approximately equal to the amount of overfeed. The reagents can be left in the fabric, which can then be pleated or creased with only a slight reduction in effectiveness compared with a normal pretreated fabric. The dimensions of the set stretch fabric will generally change by only a few percent in later processing. This change takes the form of a slight expansion in the stretch direction with a corresponding slight loss in stretch, and

a contraction in the previously stretched direction, which results in a corresponding gain in elastic stretch in that direction. Such changes are generally small enough not to cause any dilliculty in garment making-up or during wearing. However, if it is required to produce a stretch fabric with completely stable dimensions, the foregoing changes can be made to occur in the mill by rinsing the fabric after setting and then steaming for a short time while unconstrained. Such stabilized fabric will no longer be permanently ereasable because the reagents will have been removed.

Two other applications of the invention, are the permanent glossing of fabric and the permanent straightening, aligning and glossing of fibres in pile fabrics. There are several types of machines for glazing wool fabrics which could be used in conjunction with this process, but it is convenient to describe its application in connection with a rotary press. Machines for treating pile fabrics are similar in principle to the rotary press in that the fabric is held against a heated roller, but the surface speed of the roller is generally greater, the contact pressure less and the roller has spiral flutes, all of which are intended to aid the straightening and aligning of the fibres. The finishes previously produced by both types of machine using various chemical assistants were not permanent. The sequence of events in applying this invention is the same in both cases and so only one description will be given, it being understood that the statements are applicable to pile fabrics being treated on an appropriate machine or normal fabrics being glazed on the rotary press or other suitable machine.

The fabric is padded with the reagents and dried on the tenter in the normal way as described above. The dry fabric is run through the appropriate machine to produce the desired finish, set by steaming on the blower for about 5 minutes, thoroughly cooled by vacuuming in the blower and, finally, run through the first machine again. in the case of gloss fabrics, the appearance is better if rotary pressing is the last operation and, in the case of pile fabrics, the final passage through the machine is needed to lift the pile which is flattened in the blower. The finish is stable to steaming, steam pressing or wetting with water. Fabric so treated can also be permanently creased or pleated later if required.

The invention can also be applied at stages of proccsslng other than to fabric. For example, if applied at an early stage of processing, the yarn can be permanently set by steaming on the package Le. when the yarn is normally relaxed to remove liveliness. Whether or not such a setting operation is carried out, the newly woven cloth in the grey state, containing the reagents, could be steamed on the blower, as is usual to prevent cockling during later wet treatments, to permanently set the fabric. Such a permanent setting operation would he impossible with wet type treatments since the application of the solution of reagents to the loom-state cloth would cause cocitling. The reagents in the permanently-set loomstate cloth would be washed out during subsequent wet treatments and would need to be reapplied at the final stage of finishing if the fabric were to be permanently creased later.

if yarn containing the reagents is knitted into a garment or fabric, these could be permanently set by steam press ing. Such a procedure would be advantageous in the knitting industry where it is common practice to give a knitted garment no finishing treatment other than steam pressing.

The process can also be applied to flat setting of fabric on the blowing machine where water, if present, causes trouble by wetting the blowing wrapper, thus interferring with vacuuming. Such fiat-set fabric can later be permanently creased since the reagents remain in the fabric. In the same way, embossed fabrics can be produced by using a patterned blowing wrapper.

if, after permanent setting, the garment or fabric is washed, the reagents will be removed and the fabric will no longer be capable of taking a permanent set, but the permanent set imparted before washing will remain durable. However, before a wool garment can be classed as wash and wear, the wool must previously have been subjected to an anti-felting treatment. This invention can be successfully applied to wool previously shrinkproofed.

The durability of the creases or pleats depends on a combination of the concentration of setting agent, concentration of hygroscopic substance, concentration'of moisture and time of steaming. Generally,'a reduction one of these factors can be offset by an increase in the others. Thus, similar results could be obtained with low reagent concentration and long steaming time as with high reagent eoncentration and short steaming time. The quantities and identity of reagents used in the following examples represent what is considered to be industrially acceptable sets of conditions and is in no way intended to limit the scope of the invention.

Example l.-(a) Pretreatment A piece of all-wool grey worsted serge fabric (7% oz./sq. yd.) was padded through a solution containing 3.3 parts diethanolamine, 8.3 parts urea, 0.3 part anionic wetting agent (any wetting agent will do, but anionic agents e.g. an alkyl sulphate are preferred since these have poor re-wetting properties), and 100 parts water. The pressure on the squeeze rollers was adjusted to 60% pick-up resulting in a deposition of 2% setting agent and 5% urea on the weight of wool.

The fabric was then dried on a single-pass tenter at the original air-dry dimensions; air temperature I70 C.; time of passage 1 min. The fabric was rolled into a blowing machine with the minimum of tension, steamed for V4 min. then vacuumed until cool.

(b) Creasing Small samples (2" x 6") of fabric, pretreated as above were creased lengthwise and then steamed in the Hoffman press (steam pressure, 40 p.s.i.; top and bottom padding previously cooled by 5 sec. vacuum) for 30 sec.,

The durability of the creases was tested by soaking in.

water at C. for Vt hr. followed by drip-drying without distorting the crease (the fabrics were hung from one end of the create). The creases were then examined visually and the angle compared with a series of metal strips bent to known angles. Any crease which had opened by more than i or 2 degrees was rated as unsatisfactory.

The samples not pretreated lost their creases completely, while the creases in the pretreated fabric were practically as sharp as immediately after pressing. The preliminary short steam and vacuum improved the latter still further.

Crcases in samples pretreated with setting agent alone were much less sharp than those in urea/setting agent treated samples, but rather better than in untreated fabric; in general, such creases opened out to between 45' and 90', during the testing procedure outlined above.

(c) Pleating Samples of fabric were folded in pleating papers and steamed in an autoclavefor various time, either at .atmospheric pressure or at psi. The durability of the pleats was tested by soaking in water at 75 C. for A hr. and air-drying while laid flat on a sheet of glass. For samples pretreated with setting agent/urea there was no loss of pleat sharpness for steaming times greater than 20 min. at atmospheric pressure or 5 min. at 5 p.s.i., whereas similar pleats formed in untreated samples were almost completely lost. The pleats insa'mplespretreated with the setting agent alone were appreciably better than those in untreated samples, but much inferior to those in setting agent/urea pretreated samples.

Example 2 Samples were pretreated as in para. (a) of Example I but samples were retained (i) after padding and allowed to aindry, (ii) after tentering. (iii) after tentering and blowing for V: min., (iv) after tentering and blowing for 5 min. and (v) after tentering, blowing for V4 min. followed by pressing fiat for l min. as described in Example 1 for creasing. These were then creased or pleated and tested as described in Example I. The durability of creases and pleats was satisfactory in all samples with the possible exception of those in sample (iv). However sample (ii) was slightly inferior and sample (v) appreciably inferior to samples (i) and (iii) which were the same.

Samples of the above were also soaked in hot water as for the testing procedure before creasing. Samples (iv) and (v) retained their fiat surface finish whereas samples (i) and (ii) were noticeably cocltled.

Example 3 A series of samples were pretreated as in para. (a) of Example I but the solution concentrations changed to leave varying amounts of urea and setting agent on the fabric. These were creased or pleated and tested as in Example I. There was an improvement in durability with increasing concentration of either or both reagents up to 7% dicthanolamine and 20% urea (the upper limits studied). A combination of 2% diethanoiamine and 5% urea gave a crease approximately equivalent in durability to that produced with a 2% ammonium thioglycollate wet treatment as in Australian specification 225,996 and consequently, the improvement with higher concentrations was necessarily relatively small and not considered to be worth the extra cost of chemicals. Furthermore, fabric containing the maximum amounts of both reagents was noticeably stiffened. 7% diethanolamine alone or its carbonate gave similar results to 2% diethanolamine and 5% urea. i.e. the extra diethanolamlne is acting as a hygroscopic agent.

Fabric containing 2% diethanolamine and more than urea gave satisfactory creases when pressed with an unpadded bare metal top buck. Fabric containing urea alone gave satisfactory creases when pressed for l min. with a hot iron without steam.

Example 4 A sample of fabric pretreated as in para. (a), Example l, was damped with water on weight of fabric) and then creased and tested as in Example I. The durability of the crease was satisfactory.

Example 5 Samples of each treatment were creased or pleated and tested as in Example 1. All the samples containing an organic setting agent gave creases and pleats of satisfactory durability. There were slight difi'erences in effectiveness which increased in the following order: mono-, di-, and triethanolamine the same, all the carbonates and carbamates together, followed by ethylene diamine. Difi'erences would be expected since the reagents are compared on a weight rather than equivalent basis.

The creases and pleats in samples containing the inorganic setting agents were not so satisfactory, but nevertheless better than in untreated fabric, being similar to fabric pretreated with 2% of one of the organic setting agents alone.

ting agents were stored and samples periodically creased or pleated and tested as in Example 1. After about one month there was a noticeable reduction in durability with fabric containing the free bases but the durability was still satisfactory. The effect was about the same as prior fiat setting by steaming for 5 min. After 3 months the durability had fallen to an unacceptable level. The durability in fabric containing monoethanolamine carbonate decreased at a slower rate while, with diand triethanolamine carbonate and carbamate, it was still unchanged after 6 months.

I claim:

l. A process for effectively rendering heat settable a textile material selected from the group consisting of wool and other keratin fibers, comprising the steps of impregnating the material with a solution containing l) a compound selected from the group consisting of diethanolamine and diethanolamine carbonate and (2) urea, so as to leave on the material less than 5% by weight of diethanolamine, or the equivalent amount of the carbonate,

' and less than 20% by weight of urea; and drying said material.

2. A process for effectively rendering heat settable a textile material selected from the group consisting of wool and other keratin fibers, comprising the steps of impregnating the material with a solution containing a compound selected from the group consisting of diethanolamine and diethanolamine carbonate, so as to leave on the material from 5% to 25% by weight of diethanolamine, or the equisl'alent amount of the carbonate; and drying said matcria 3. A substantially dry heat settable textile material selected from the group consisting of wool and other keratin fibers, and containing (1) a compound selected from the group consisting of diethanolamine and diethanolamine carbonate in an amount less than 5% by weight of diethanolamine, or the equivalent amount of the carbonate, and (2) less than 20% by weight of urea.

4. A substantially dry heat settable textile material selected from the group consisting of wool and other keratin fibers and containing a compound selected from.

(References on following page) 9 10 References Cited 3,059,990 10/ 1962 Kocnig at al 117-14l X UNITED STATES PATENTS 2,382,632 8/1945 H3861 61 a1. 8127.6 10 1959 Schrocdcr 117 14 WILLIAM D. MARTIN, Primary Examiner.

1/1950 Lccompte 8-1216 5 'r. G. DAVIS, Assistant Examiner. 9/1950 Angus et a1. l17-14l X Us Cl XR 4/1956 Littleton at a] 117141 X 10/1962 Kocnig 28-76 117-11, 139.4; 8-127.6, 128