US2238839A

US2238839A - Crease-resisting treatment of textile materials

Info

Publication number: US2238839A
Application number: US285625A
Authority: US
Inventors: Watkins William
Original assignee: Individual
Current assignee: Individual
Priority date: 1935-08-17
Filing date: 1939-07-20
Publication date: 1941-04-15
Anticipated expiration: 1958-04-15
Also published as: GB465939A; GB465875A; BE420669A; NL54409C; FR829828A

Description

Patented Apr. 15, 1941 CREASE-RESISTING TREATMENT OF TEXTILE MATERIALS ,William Watkins, Prestwich, Manchester, England No Drawing. Application July 20, 1939, Serial No. 285,625. In Great Britain August 17, 1935 Claims.

This invention relates to the finishing of textile fabrics for the purpose of imparting creaseresistant and crease-recovery properties thereto (as for example in the case of fabrics of cotton and artificial silks, which have little or none of such properties naturally), or for the purpose of improving the natural crease-resistant and crease-recovery properties thereof (as for example in the case of fabrics of silk and wool) without in either case depriving the materials of their natural suppleness or softness.

The present application is in part a continuation of my co-pending application Serial No. 110,- 306 filed November 11, 1936, entitled Crease-resistant treatment of textile materials.

Fabrics are considered crease-resistant when they may be crushed or folded under pressure as by being crumbled in the hand, without having a permanent crease imparted to them, and are considered to have crease-recovery properties when, after being marked by crushing or crumpling, they recover from such marking;

In previously known processes for this purpose, there has been an aim to cause the fibres of the fabrics to be impregnated with reinforcing substances comprising synthetic resins, and in such manner as to deposit the resin substantially within whilst avoiding its presence between the fibres in substantial amounts. Such known processes have necessitated the application of relatively large quantities of the resin-forming bodies; have inhibited the use of fillers in the reinforcing substances except in very small amounts insufficient to impart a filled or loaded effect to the fabrics; and have entailed the removal (as by soaping-off) of the surplus resins to ensure there being substantially none between the fibres in the finished product. These requirements have rendered the process costly and have limited the range of fabrics to which they can be applied,

The principal object of the present invention is to provide a process or processes of finishing textile fabrics, for the purpose set forth, which is or are entirely free from the drawbacks and limitations of the said previous proposals in that (a) much smaller quantities of reinforcing substances may be used (although the invention is in no way restricted to the use of small quantities) and the fine molecular division of the applied bodies is not a necessity, since it is immaterial whether the reinforcing substances are substantially within the fibres or merely coat them, or do both; (b) in which fillers or loadings may be used with the reinforcing substances, if

desired, in amounts sufficient to give filled or loaded effects; and (c) in which there is no necessity for removing any surface deposit or surfibres) is not detrimental to the process, and does not detract from the natural suppleness and softness of the, materials, at least to any adverse extent.

A furtherobject of the invention is to render the reinforcing substances, when of a hygroscopic nature, less or non-hygroscopic, and thus lessen or entirely obviate the tendency of the anti-crease finish to diminish during the passage of time, and also permit the use of a wider range of reinforcing substances.

The present invention is based upon the realisation that the essential requirement'in a creaseresistant or crease-recovery fabric is that the fibres should be individually reinforced to the correct degree, and that they should not adhere together, but should be as free from each other as in any ordinary untreated fabric, so that relative movement may take place between them when the fabrics are subjected to distortion, and so that the separated reinforced fibres may be free to accommodate themselves to new relative positions without losing their imparted springiness and permanent set. Given. such requirement, it appears to be a matter of little or no importance whether the reinforcing substances are impregnated within, or are substantially between the fibres or are in both such dispositions.

The present invention consists in applying to the fabrics in the form of a solution or dispersion reinforcement-forming substances of an aldehyde-hardenable nature selected from the group consisting of animal and vegetable filmforming substances and synthetic-resin-forming substances, in drying the fabrics after the application of such substances, in mechanically working the fabrics to unstick the constituent fibres from each other, and in heat treating the fabrics in the presence of an, aldehyde and an accelerator, the heat treatment being such as to harden the reinforcement-forming substance sufficiently to give the fabrics crease-resistant properties.

Usually the fabrics will be dried after the application of the reinforcement-forming substances, and before the mechanical treatment is carried'out on the fabric. In some cases however, the mechanical treatment may be carried out during the drying and/or hardening treatments. Generally, however, the mechanical treatment is done after the fabrics are dried and before the reinforcement-forming-substa1uces are hardened, and in such cases the fabrics require to be kept dry, in order to prevent the fibres re-- sticking together, as might be the case where the unhardened substances are soluble in water. The

term dry in this connection means normally dry, 1. e. the state of dryness which would subsist in a normal atmosphere.

By the term reinforcement-forming sub- 'to impart to the fabrics a more vigorous individual fibres, and which can then be hardened by chemical treatment to a degree sufiicient a springiness or temper, the effect of which on the fabric be described as an anti-crease effect, according to the standards now adopted. Those dispersions or other forms of substance which on evaporation leave a granular or non-continuous deposit incapable of imparting the required springiness or temper, are not intended to be included in the term reinforcement-forming substances.

The solutions or dispersions of the reinforcement-forming substances are frequently of a viscous consistency, more of a paste than a liquid,

"but as entry or the substances within the fibres the success of the invention,

is not essential to this is no disadvantage.

The term "aldehyde-hardenable reinforcement-forming-substance means a substance as defined in the last preceding paragraphs and which may be hardened by heat-treatment'in the presence of formaldehyde, paraform-aldehyde or an analogous or homologous aldehyde.

The reinforcement-forming substances will be of an adhesive or film-forming nature and may include such widely diverse substances as casein, albumen, starches, modified starches, dextrine,

. animal glues and gelatines, vegetable gelatines (such as those obtained from sea-weed), locustbean gum, gum arabic and like gums, algin, and metallic salts of alginic acid, and some of the synthetic resin-forming substances, all of which have the property of being hardened by heattreatment in the presence of an aldehyde, to form reinforcements to the extent required for an anti-crease effect. Some'oi the reinforcementforming substances named are more efiective than others.

V In this specification, the term mechanical treatment is intended to include any mechanical or manual treatment which will separate (unstlck or prevent sticking together of) the individual fibres to which the reinforcement-forming sub stances have been applied, and does not include such processes as boiling or soaping off or other chemical treatment. The fabrics will in .most cases require to be treated both in a warpwise and weftwise direction at least. One method of mechanical treatment contemplated by this invention, and applicable to the treatment of fabrics according to all the following examples is the passing of the fabric under and over breaker bars and through a cold nip on a mangle several times, the treatment being carried out to a sufficient degree of intensity and a sufficient number of times to separate the individual fibres, A

.stentering process, or the use of cxpanders may be included to give a weftwise treatment, especially if the fabrics havebeen dried narrow. For treating small articles, a manual treatment by crumpling and scrubbing together severely would have the desired result. Some of the substances named hereinrequire a more intensive mechanical treatment than others, the degree of treatment depending upon the adhesive power of the applied substances. For instance, starch requires treatment than does albumen.

It is to be understood that not only are the threads of a fabric to be unstuck from each other, but also the component fibres of the threads are to be unstuck, from each. other. The word unstuck is used merely to qualify the term sepis entitled to,

aration, in that it is not to be a separation by complete removal of the fibres out of contact with each other, as bytearing apart, but is to be merely an avoidance of or elimination of adhesion together. The basis of the invention is that the fibres, having had their springiness increased by the hardened'applied substances, are to be free to move relatively to each other; and a mechanical treatment during drying or hardening which would prevent sticking of the fibres together would serve the purpose also. The primary object of the mechanical treatment is to unstick the fibres and thus make their relative movement possible. It is a colateral result of the mechanical treatment that the fabrics are rendered less harsh or stiff, and although such colateral result is useful, and is desired, the anticrease effects depend fundamentally on the mechanical treatment being sufficiently intensive to bring about the separation (loosening) of the fibres, and on the fibres having the required degree of springiness.

The term hardening connotes a reaction which increases the hardness of the applied reinforcement-forming substances to such a degree that the treated fibres are rendered sufficiently springy to impart an anti-crease effect to the fabric. It has been found that the degree of hardening required is such that if applied to the reinforcement-forming substances alone, i. e., when not on or in textile fibres, it will make the resultant substance hard and brittle, i. e. glasslike. When the. reinforcement-forming substances are hardened to this extent, on or in the fibres of a fabric, the natural plasticity ofthe fibres modifies the brittleness of the reinforce- I ment, and the hardening process then results, in

springy, tempered, fibres, which collectively give to the fabric a resistance to creasing.- Any less degree of hardening which would merely leave the resultant substance flexible if treated alone (i. e., when not on or in textile fibres) or which would be overcome by the natural plasticity of the fibres it carried out thereon or therein, is

found not to be sufficient and is not contemplated able that some reinforcement-forming substances (as for instance some synthetic resin-forming bodies) will be self-hardening over a period of time, and the term hardening'is intended to include such ageing processes. In those cases,-

also, if, the fibres, have been separated, care will be taken to prevent any re-sticking of them by dissolving of the reinforcement-forming substances during the ageing period. Further, in some cases the hardening process will be carried out under pressure, if the required degree of hardness is not obtainable otherwise; This will be especially so with the natural substances such as casein, starch etc., where the anti-hygroscopic bodies referred to below are not added to the reinforcement.

During the hardening process, it is necessary that there be an accelerator present with the reinforcement-forming-substance and the aldehyde, and also that there be an excess of the aldehyde, that is to say, a greater quantity of aldehyde than is theoretically necessary to harden the reinforcement. It is believed that, with an excess of aldehyde present, not only does the aldehyde react with the reinforcementforming substance, but also with the fabric itself, and that such collateral reaction is useful in giving permanence to the anti-crease effect.

The aldehyde which is to take part in the hardening process, may be applied to the fabric,

in various ways. Most conveniently it is added to the solution or dispersion of the reinforcementforming-substance, with which the fabric is to be impregnated, and applied to the fabrics in that solution or dispersion. When however the reinforcement-forming-substance is such as would react with or be precipitated by the aldehyde if added to the solution or dispersion, that substance (in solution or dispersion) will be applied to the fabric first, and the fabric, with or without an intermediate drying and mechanical working,

then passed into a solution or dispersion of the aldehyde and accelerator, and whatever other substances are to be present during the heat treatment. Alternatively, the fabric may be passed through an aldehyde both first of all before having the reinforcement-forming substance applied to it, and in such event as well as when the reinforcement-forming substance and the aldehyde are applied simultaneously, the fabric may be allowed to steep in the bath for several hours, as this improves the result obtained.

Other methods of applying the aldehyde (for example paraformaldehyde) to the fabric are:

(a) Paraformaildehyde powder may be placed in the enclosed chamber in which the hardening is to be effected, the powder volatilising under the influence of heat and thereby obtaining contact with the treated fabrics; (b) The paraformaldehyde powder may be dusted on to the fabrics in known manner, say prior to their being placed in the pressure chamber, and the heat and pressure applied as in the previous case: (c) The paraformaldehyde may be dispersed in a viscous, inert, non-alkaline solution and padded on ma back-cloth, the back-cloth then being dried at a low temperature (say 40-50 C.) to prevent premature volatilisation and the treated fabric and back-cloth be rolled up together in batch form and placed in the heating chamber, the

paraformaldehyde being driven off as the temperature is raised, and hardening the reinforcing substances in the treated fabric. In this lastmentioned instance, there is not the same need for an increase of pressure in the chamber, since the aldehyde vapours are more or less imprisoned due to the rolling-up of the fabrics, and generate a sufficient pressure by their vapourisation. (d) The fabric is sprayed with formalin solution. Generally the amount applied and/or the concentration of the solution is such that there is sufficient formaldehyde to effect the hardening, but not sufficient water to cause the fibres of the treated fabrics to stick together. After having been sprayed, the fabric is allowed to sand a little while to allow the solution to distribute itself evenly in the fabric, and the fabric is then placed in the heating chamber as usual: (e) Where the padding solution or paste containing the reinforcement-forming substances is sufilciently viscous to hold the paraformaldehyde in suspension, the paraformaldehyde may be dispersed in such padding solution or paste. In this case, the drying of the padded material will be carried out carefully so as not to vapourlse the paraiormaldehyde prematurely. In this method of application, no free alkali is allowed to be present as it would cause the paraformaldehyde to go into solution, with apparent alteration of its properties, since it wouldnot then do its hardening work so effectively.

Accelerators suitable for use in the hardening reaction are acid salts such as potassium tetroxalate, sodium bisulphate and alumina sulphate; acid-liberating salts such as ammonium salts of organic and of inorganic acids (e. g. ammoniuml oxalate, ammonium chloride and ammonium phosphate); and some weak acids, such as tartaric, acetic, and oxalic acid. Other accelerators which may be employed are ammonium dihydrogen phosphate; and small amounts of urea mixed with ammonium chloride or with alumina sulphate or with formic acid.

During the hardening process, the presence of moisture will be carefully controlled so that whilst there will be sufficient moisture present (if necessary) to enable the reaction to proceed, there will be insufficient to cause the fibres to restick together. In some cases it may be necessary to condition the fabric, as by ageing, after drying and before heat-treating it. If by accident (or otherwise) there should be a resticking of the fibres, due to some of the reinforcementforming substances going into solution, a further mechanical treatment may be adopted, before or after the hardening treatment, to undo any such resticking. The separation of the fibres is of course more dimcult to effect after the hardening treatment than before, and in some cases might be impracticable.

The hardening treatment with paraformalldehyde or the like is carried out at an elevated temperature, either at atmospheric pressure, as for instance in an open oven, or at a superatmospheric pressure in a closed chamber. A mechanical pressure would not be used, as that would tend to stick the fibres together again. When synthetic resins are to be the reinforcing-substances the whole of the reaction between the resin-forming materials, may be completed in one stage.

When synthetic resins are used as the reinforcing-substances, the improved process presents at least three outstanding advantages over the prior proposals referred to above, in which the resins had to be substantially within and not between the fibres. Firstly, the quantity of resins necessary is much less than is required in the prior art; secondly, it is not necessary to condense the resins to an intermediate stage before their application to the textile materials; and thirdly, loading or filling materials may be added to the resins in quantities sufficient to give loaded or filled effects without detriment to the anti-crease result. Examples of loadings or fillers which may be added with the synthetic resins are French chalk, alumina salts, gum substances, starches,

and dextrines, with or without a thickener when desired to assist their dispersion. The use of certain of the gum substances is especially beneficial as they overcome or counteract any harshness or dryness of feel which may otherwise be imparted to the fabric by the resins. It is a Wellknown fact that, weight for weight, a tube of material is, within certain limits. more resistant to bending than-is a rod. Since, by this invention, the reinforcing substances may be coated on the fibres in the form of a sheath or tube, as would be the case with such substances as starches, which do not readily penetrate the fibres. the present invention gives a more eflicieiit and, in consequence, lose their reinforcing properties too rapidly, have their hygroscopy removed or counter-acted by the admixture with them or the formation among them of suitable nonhygroscopic bodies, such as those of the synthetic resins which do not interfere with the hardening process. This step is not always required; for instance, when voiles or like fabrics dyed with aniline black are being treated, the very inert,

aniline pigment may itself be sufficient to counter-act the hygroscopic nature of the reinforcing substances.

Usually, those of the reinforcement-forming substances which are natural products, as distinct from the syntheticproducts will be hygroscopiceven after hardening and will therefore require to have the anti-hygroscopic substances added to them (unless these are already present in suflicient amounts in the fabrics) when more permanent results are. desired.

In carrying out this feature of the invention, since the condensation or polymerization of the synthetic resins (when used) to counteract hygroscopy may be effected by a process which will also harden the reinforcement-forming, substances, namely by heat-treatment with an aidehyde, the resin-forming bodies may be mixed with the reinforcement-forming substances, the

two applied to the textile fabrics in one operation, and the two reactions then carried out simultaneously. The proportions of synthetic tresins necessary in this part of the process, merely for their anti-hygroscopic properties, are, even in the largest amounts, insufficient of themselves to impart satisfactory crease-resisting effects to the fabrics.

In useful examples of the carrying out of the invention, where the reinforcing substance is other than casein, such substance is dissolved or dispersed in water to a concentration of say avoiding the presence of alkalies, and a quantity of an aldehydesubstance, such as formaldehyde, is added to the solution or dispersion. The fabric is first impregnated with the solution or dis- 'persion and afterwardsnipped off on a "mangle solution or dispersion. The fabric is next dried thoroughly, at about 110 C., and is then broken down, for example by being passed over and under knife-edged bars and through a cold nip on a mangle (Whilst still dry) to a degree. sumcient to separate the fibres, and is then heat treated, wither without pressure at a temperature of about 130 C. for a period long enough to convert the applied reinforcing substances into a hard, non-plastic, non-adhesive, insoluble condition which gives to the fabric crease-resistant and crease-recovering properties. When it is de sired that the reinforcement-forming substances give greater weight to the fabrics, the concentra tion of the solution or dispersion may be increased considerably.

When casein is to be employed as the reinforcing substance, variations in the above procedure are required. The fabric is first impregnated with EXAMPLE1.Reinforcement formed from casein The fabric is first impregnated with a 3% to 5% aqueous solution of casein, the casein having been brought into solution with the aid of ammonia, and is then dried and afterwards broken down to separate the fibres from each other. When thoroughly broken down, the fabric is impregnated with the following:

Urea in the form of 4 ccs. of a com- 0.6 Thio-urea mercial resin syrup grams 0.6 Potassium tetroxalate do 0.4

Formalin (commercial 40%) cubic centimeters 30 The total being made to 100 ccs. with water.

The fabric was allowed to remain in this mixture for two hours, at the end of which time it was removed from the bath, nipped off in a mangle, and dried thoroughly at C., and then subjected to a second breaking down treatment to separate the fibres from each other again. After being conditioned to an 8% moisture content (or thereabouts) the fabric was heated for 30 minutes at a temperature of 130 C. The heat-treatment may be carried out at atmospheric or superatmospheric pressure as desired.

The ultimate product was found to havemarkedly increased resistance to creasing, and to meet the generally-adopted commercial standards of crease-resistance.

The resin formed from the syrup acts as a protector for the casein, to present hygroscopy in the finished article, the quantity of resin used being much too little to be of itself a reinforcement for the fibres of the fabric. Other protectors which maybe used with casein for a like purpose are, resorcin and lime, phthalic acid resins, and like substances which will harden to the required degree.

EXAMPLE 2.Reinforce1rtent formed from. casein The fabric was treated as in Example 1, except that the aldehyde-containing impregnating bath was made up asfollovvs:

Tartarlc acid grams 2 Alumina sulphate do 0.5 Urea do 1 Formalin (commercial 40%) cubic centimeters 20 Made up to ccs. with water.

ExAMrLE 3.--Reinforcement formed from albumen The fabric was impregnated in the following: Blood albumen grams 5 Tartaric acid do 1 Alumina sulphate -do 1 Formalin (commercial 40%) cubic centimeters 20 Buiked to 100 ccs. with water.

After remaining in th bath for two hours the fabrics were removed, dried thoroughly at 90.C., broken down to separate the fibres, conditioned to 8% moisture content, and heated for 30 minutes at 130 C. either at atmospheric or super-atmospheric pressure, as desired.

EXAMPLE 4.Reinforcement formed from albumen The fabric was impregnated in the following for two hours, and the process then continued as in Example 3.

Blood albumen grams Tartaric acid do 2 Alumina sulphate do 1 Urea 1 Formalin (commercial 40%) cubic centimeters..- 20 Bulked to 100 ccs. with water.

ExmLs 5.--Rein/orcement formed from albumen The fabric was impregnated in the following for two hours, and the process then continued as Tartaric acid grams 2 Bulked to 100 ccs. with water. 1

EXAMPLE 6.Reinforcement formed of resin The fabric was impregnated in the followin for two hours, and the process then continued as in Example 3, except that the drying was carried out at 110 C:

Commercial resin syrup (contained 3.32 grs. urea resin and 3.32 grs. thio-urea resin) cubic centimeters-.. 12

Formalin (40%) -do Tartaric acid ram-.. 1

Bulked to 100 ccs. with water The above examples may be modified, in that instead of the fabric being steeped in the solution a straightforward impregnation or padding-on may be carried out.

EXAMPLE 7.--Reinfcrcement formed of resin The following mixture was padded on to the fabric and the fabric then dried at 110 C., and the process then continued as in Example 3.

Resin syrup (commercial) cubic centimeters' Formalin (40%) do 10 -Tartaric acid grarn 1 Bulked to 100.ccs. with water.

Examms 8.-Reinforcement formed of a filled resin To 10 cos. of commercial resin syrup, containing 6 grms. total resin was added:

Formalin cubic centimeters 20 Locust-bean gum paste -grams French chalk do 10 Potassium tetroxalate do 0.6 Water -cubic centimeters" 19.4

Total do 100 onwhite materials. It could, however, be tinted for use on coloured goods.

Exmtn 9.Rein,forcement formed from a metallic salt of aluinic acid To 75 cos. of 5% alg inate of alumina solution was added:

Formalin (40%) -cubic centimeters-.. 25 Water solution of a commercial resinsyrup containing 0.66 grm. urea and 0.66 grm. thio urea, already converted to an intermediate stage of concentration ccs- Bulked to ccs. with water.

The fabric was impregnated in the mixture and the process then continued as in Example 8.

Exsuru: 10.Reinjorcement formed from starch To 4 grms. of starch made to a paste in the usual way was added:

Commercial resin syrupmcubic centimeters 6 Tartaric acid "grams" .5 Alumina sulphate do .5 Formalin 40% cubic centimeters 3 Bulked to 100 cos. with water.

The fabric was impregnated with the mixture and the process continued as in Example 8.

Other gums or fillers can be used, and also where a waterproof effect is desired at the same time this can be obtained by the addition of acetate of alumina.

The processes constituting this invention may be applied to textile fabrics which have passed through the usual so-called finishing processes (dyeing, lustring, mercerlsing, etc.) or to unfinished or semi-finished materials, and in some cases may be incorporated with the usual finishlng processes.

It is to be understood that the invention is not restricted to the individual substances, quantities, temperatures and pressures herein set forth, nor are the time periods mentioned the only periods practicable.

What I claim is: i

1. The process of imparting crease-resistant properties to textile material, which includes loading the fibres of the material with an encasing of aldehyde-hardenable organic reinforcement-forming substance, drying the, material after the application of the aldehyde-hardenable substance to form a coating around the constituent fibers, then subjecting the material while still dry to mechanical treatment without breaking the coating of the fibres to render the fibres in a state of non-adhesion to each other, incorporating an aldehyde capable of reacting with the aldehyde-hardenable reinforcement-forming substance to harden the same, and hardening the reinforcing substance by heat under superatmospheric pressure to a degree sufficient to give the material crease-resistant properties.

2. A process according to claim 4 in which the aldehyde-hardenable substance is starch.

3. A process according to claim 4, wherein the aldehyde-hardenable substance is a synthetic urea formaldehyde type resin-forming substance.

4. A process for imparting crease-resistant properties to textile fabric which includes applying to the fabric a liquid medium containing an. aldehyde-hardenable film-forming organic reinforcement substance, drying the fabric to deposit such substance as a coating around the constituent fibers, mechanically working the fabric to unstick the constituent fibers from each constituent fibers, mechanically working the fabric to unstick the constituent fibers from each other without breaking the reinforcement coating carried by the individualfibers, and heat treating the fabric under super-atmospheric pressure in contact with an aldehyde and an accelerator, the heat treatment being such as to harden the reinforcement-forming substances sufflciently to give the fabric crease-resistant properties.

6. A process according to claim.4 in which there is included with the film-forming substance, added aldehyde-hardenable non-hygroscopic bodies in an amount suflicient to counteract hygroscopy in the reinforcement.

7. A process according to claim 4 in which there is included with the film-forming substance prior to its application to the fabric, synthetic urea formaldehyde type resin forming materials and forming the resin during and by the heat treatment which forms the reinforcement.

8. A process according to claim 4 in which the hardenable substance is an albuminous substance.

9. A process according to claim 4 in which the hardenable substance is an albuminous sub!- stance, and in which there is included with said albuminous substance, synthetic urea formaldehyde type resin forming materials and forming the resin during and by the heat treatment which forms the reinforcement.

10. A process for rendering textile fabric crease-resistant, which includes first padding onto the fabric to an expression of from to a 5% dispersion in water of an albuminous substance, next in drying the fabric at about C. to form a coating around the constituent fibers, then in conditioning the fabric to about 8% moisture content, next in mechanically treating the fabric by passing it several times through a breaking machine and through a cold m'p on a. mangle to unstick the fibers, and finally in heat-treating the fabric in contact with an aldehyde at a temperature of about C., for 30 minutes.

WM. WATKINS.