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Publication numberUS3511747 A
Publication typeGrant
Publication dateMay 12, 1970
Filing dateAug 13, 1968
Priority dateMar 1, 1963
Also published asDE1469247A1
Publication numberUS 3511747 A, US 3511747A, US-A-3511747, US3511747 A, US3511747A
InventorsStanley Davies
Original AssigneeBritish Nylon Spinners Ltd
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Bonded textile materials
US 3511747 A
Abstract  available in
Images(3)
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Claims  available in
Description  (OCR text may contain errors)

y 2, 1970 5. DAVIES 3,511,747

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May 12, 1970 s. DAVIES BONDED TEXTILE MATERIALS 3 Sheets-Sheet 2 Filed Aug. 13. 1968 FIG. 2

mW wm m 3% y M W S- DAVIES BONDED TEXTILE MATERIALS May 12, 1970 Filed Aug. 15, 1968 3 Sheets-Sheet 5 FIG.3

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U.S. or. 161-150 United States Patent 3,511,747 BONDED TEXTILE MATERIALS Stanley Davies, Pontypool, England, assignor to British Nylon Spinners Limited, Pontypool, England, a corporation of Great Britain Continuation-impart of application Ser- No. 346,752, Feb. 24, 1964. This application Aug. 13, 1968, Ser. No. 752,389 Claims priority, application Great Britain, Mar. 1, 1963, 8,209/63 Int. Cl. D04h 1/04 16 Claims ABSTRACT OF THE DISCLOSURE A bonded textile material containing fibres consisting of' at least two fibre forming synthetic polymer components arranged in distinct zones across the cross-section of each fiber, at least one, but not all of which components are potentially adhesive and located on at least a portion of the'periphelal surface thereof. The fibers are bonded by the adhesive material, but do not form crirnps during the formation of the mat due to the application of pressure during bonding.

This application is a continuation-in-part of U.S. application Ser. No. 346,752, filed Feb.'24, 1964, now abandoned.

Thisinvention relates to bonded fibrous materials and more particularly to fibrous materials which are bonded together by the. adhesive characteristics of at least a proportion of their constituent fibres.

It has already been proposed to adhesively bond fibrous materials by incorporating homogeneous binder fibres in the materials, the binder fibres generally being rendered adhesive by the action of heat or a solvent. However, when such fibres are rendered adhesive under conditions such as to obtain a product having adequate strength, they lose their fibrous form and the adhesive spreads through the structure, rendering the materials stiff and conferring on "advantages'as those bonded with homogeneous binder fibres. Frequently thermosetting resins have been used as the coating material and these resins produce even stiifer and harsher materials since the thermosetting resins polymerise to a hard brittle infusible mass. Further disadvantages resulting from the use of fibres coated with a nonfibre-forming resin include difiiculties encountered in dyeing the coating and economic difiiculties associated with the manufacture of such fibres.

It is an object of the present invention to provide v bonded fibrous materials which have adequate strength but are less stiff and more attractive to handle than the prior art fabrics, and I have found that if particular composite -fibres are used as binder fibres then this objective is achieved.

Composite fibres containing two or more fibre-forming synthetic polymeric components, the components extendlice ing along the length of the fibres, are known and have been used in fibrous structures. I have now found that if the components of the composite fibres are chosen so that at least one but not all of the components are potentially adhesive, that it can be rendered adhesive by a treatment which-leaves the remainder of each fibre substantially unaffected and such fibres are used to form fibrous structures then the potentially adhesive components do not lose their 1 fibrous form on being rendered adhesive under conditions such as to produce an adequately bonded structure. The potentially adhesive components remain associated with the remainder of each fibre thus producing a structure in which adhesive binder is confined to small areas where fibres are in contiguous relationship and, since there is no spread of adhesive, the bonded structures are less stiff and more attractive to handle than prior art fabrics.

Thus according to the present invention, in one of its aspects, there is provided a bonded textile material of a fibrous character comprising at least five percent, based on the weight of fibres in the material, of composite fibres substantially free of helical crimp which fibres consist of at least two fibre-forming synthetic polymeric components arranged in distinct zones across the cross-section of each fibre, at least one but not all of which components is potentially adhesive and located in said fibres so as to form at least a portion of the peripheral surface thereof, the fibres in said material being bonded together where they are in contiguous relationship by the adhesive characteristics of said potentially adhesive component.

According to the present invention, in another of its aspects, there is provided a process for making bonded textile materials which comprises forming a fibrous structure containing at least five percent by weight of composite fibres which consist of at least two fibre-forming synthetic polymeric components arranged in distinct zones across the cross-section of each fibre, at least one but not all of which components is potentially adhesive and located in said fibres so as to form at least a proportion of the peripheral surface thereof and bonding the fibres together where they are in contiguous relationship by rendering adhesive the potentially adhesive component of said composite fibres without causing said composite fibres to crimp helically.

For convenience the following discussions will refer to two component composite fibres although it is to be understood that such fibres may, if desired, have more than two components. As used herein the word fibre includes continuous filaments and staple fibres including flock.

The particular treatment used to elfect bonding depends on whether or not the composite fibres used possess potential helical crimp. For instance, if the components of the composite fibres are arranged in a symmetrical sheathcore relationship then the fibres may not possess potential helical crimp and it will not be necessary to prevent potential crimp from being developed during bonding. If, for instance, the components are arranged in a non-symmetrical sheath-core relationship or side-by-side or if the fibres are non-circular, e.g. trilobal, with'the components having a non-symmetrical relationship e.g. one or two of the lobes being formed by the potentially adhesive component, then the fibres may possess potential helical crimp and it is necessary to prevent such crimp from being developed during the bonding operation. The development of helical crimp in the composite fibres can be prevented by subjecting the structure to a restraining pressure, for instance by using plates or rolls or belts, during bonding, a pressure of about gm./cm. generally being sufficient. Of

course fibres'not possessing potential crimp maystill be subjected to pressure during bonding in order to increase the amount of bonding.

The composite fibre structures can be subjected to a variety of treatments to render adhesive the potentially adhesive component and the particular treatment used in any particular instance depends, to a large extent, on the in which the poly-epsilon caprolactam component has the lower softening point, poly(omega-aminoundecanoic acid) lpolyhexamethylene adipamide (nylon 11/66) fibres in which the poly(omega-aminoundecanoic acid) component has the lower softening point and polyhexamethylene adipamidelpolyhexamethylene adipamide poly-epsilon caprolactam copolymer (nylon 66/ 66/ 6) fibres in which the copolymer component has the lower softening point.

When the potentially adhesive component is heat activatable and the composite fibres do not possess potential helical crimp, suitable treatments for rendering adhesive the potentially adhesive component and bonding the fibres in the structure together include those not utilizing the application of pressure for example the use of dry heat such asin a hot air oven or in a radiant heater or the use of a hot liquid media or steam either superheated or saturated.

When the potentially adhesive component is heat activatable and the composite fibres possess potential helical crimp suitable treatments for rendering adhesive the potentially adhesive component and bonding fibres in the structure together include, for example, subjecting: the

' fibrous structure to the application of heat and pressure,

as by pressing the structure between heated plates or by passing it through heated calender rolls or by treating the structure while under pressure with a hot liquid media (e.g. hot or boiling water) or steam either superheated or saturated.

When the potentially adhesive component is such that it can be-activated by a chemical treatment, activation and bonding can be achieved by subjecting the fibrous structure to a suitable chemical action with or without the application of pressure depending on the composite fibres used. An example of such a composite fibre is one consisting, for example, of various proportions by weight (for example equal quantities) of polyhexamethylene adipamide as one component and a random copolymer (for example an 80:20 copolymer) of polyhexamethylene adipamide/poly-epsilon 'caprolactam as the other compponent. The copolymer component in such composite fibres can be activated i.e. rendered adhesive by treating the fibrous structure with a hot (100 f non-aqueous, for example, ethylene glycol, solution of formaldehyde, under conditions which leave the polyhexamethylene adipamidecomponent of the composite fibres substantially non-adhesive. Alternatively, the copolymer component may be activated by treating the fibrous structure in a bath of nitric acid of a suitable strength. After bonding the chemical media employed for activating the potentially adhesive component is removed by any suitable means such, for example, as evaporation or washing i with a liquid miscible with the aforementioned chemical media but inert towards fibres in the fibrous structure.

Suitable components for producing the composite-fibres can be found in all groups of synthetic fibre-forming i materials. Because of their commercial availability, ease of processing and excellent properties, the condensation polymers, for example, polyamides, and polyesters, .and particularly those which can be melt spun are very suitable for use in the present invention. Other composite C.) essentially fibres which may be used include, for example, those based onor containing polyesteramides, polysulphona- Potentially adhesive component Polyhexamethyleiie adipamide. Poly(omegaraminoundeeanoie aci Do Polyhexarnethylene adipamlde and poyi-epsilon-caprolactarn copclyemr (various proportions of thgttwo components by weig D0 .L. Polyhexamethyleno adipamide and polyhexamethylene sebaear mlde copolymer (various proportions of the two components by weight). v copolymer (various roportions by weight) of polyet yleneterephthalate and polypropylene- Polyethyleneterephthalate A terephthalate. Polypropylene Polyethylene. Poly exarnethylene adipamide. A su table polyurethane. Polyethyleneterephthalate A suitable polyethsr-polyurethane copolymer.

Such composite fibres hold their shape and retain their identity as fibres during activation of the potentially adhesive component by virtue of the fact that the other component of the fibres is relatively unaffected by the activation treatment.

A number of methods are available by which the composite fibres may be prepared. Thus, for example, they may be prepared by the methods described in British Pats. Nos. 579,081, 580,764, and 580,941 which involve cospinning by a process of melt, plasticised melt, wet or dry spinning, the polymer materials so that they form a unitary filament. Suitable processes and apparatuses for use in the production of composite fibres in which the components are in a side-by-side relationship by melt spinning, are, for example, described in the specifications of our British Pats. Nos. 953,379 and 1,035,908. Prior to or during the spinning operation there may be added pigments, plasticisers, dyes, moth-proofing agents, fire-proofing agents, fillers, abrasive and/or light stabilisers. In particular when the potentially adhesive component is heat-activatable it may be desirable to add to the spinning solution or otherwise incorporate into the potentially adhesive component suitable substances for lowering the softening point of that component, such, for example, as plasticisers, soft resins and the like. Among suitable plasticisers for this purpose are dibutyl tartrate, ethyl phthallate, and ethyl glycollate. Examples of suitable soft resins are polyvinyl acetate, ester gum coumarone resin and the lower molecular weight alkyd resins.

It is only necessary that the fibrous structure and the bonded textile material derived therefrom composise 5 percent composite fibres containing a potentially adhesive component, although I prefer such fibres to be present in an amount of 10 percent or more, and other fibres which are inert or substantially so to the activation treatment to which the fibrous structure is subjected may be employed as a blend with such composite fibres. Depending upon the particular desiderata in the bonded textile material to be produced, the percentage of composite fibres containing a potentially adhesive compound present in the fibrous was and the bonded textile material derived therefrom may be varied widely.

The composite fibres either in the form of continuous filaments or staple fibre including flock, may be associated with other fibres or continuous filaments of almost any sort, the only substantial limitation being that those other fibres must be inert to the treatment rendering adhesive the potentially adhesive component. Wool, silk, flax, cotton, regenerated cellulose, mineral fibres including ass bestos and rock wool, glass fibres, synthetic polymeric fibres (for example, polyamide and polyethyleneterephthalate fibres), other composite fibres and the like are examples of such fibres which may in a particular instance be suitable. For the purposes of this specification and appended claims we term such fibres non-activatable fibres.

The fibrous structures containing the composite fibres may be utilised in the textile art in numerous ways and the structures may take various forms depending upon the particular bonded textile material desired.

Thus, in the preparation of a woven or knitted fabric the composite fibres either alone or in admixture with non-activatable fibres may be carded and then subjected to drafting and spinning to produce a yarn. The yarn after it has been woven or knitted is then treated to render adhesive the potentially adhesive component. This treatment serves not only to stabilise the structure of the yarns within the woven or knitted fabric but also to stabilise the structure of the fabric as a whole by adhesion of fibres at points of inter-crossing of the Weft and warp or of loops in the knitted fabric. In continuous filament form the composite fibres containing a potentially adhesive component may be fabricated into cords by plying, after which the plies may be bonded together.

Besides mixing filaments of relatively short lengths such as staple fibres in the manner contemplated in the descriptions hereinabove, the yarns may be formed of continuous filaments some or all of which are composite fibres and such yarns maybe formed into wovenor knitted or plied fabrics in the same manner as a staple fibre yarn.

Utilisation of composite fibres in this manner affords textile fabrics of a knitted, woven or plied character wherein the tendency of the component yarns and filaments to slip with respect to the others is virtually elimi nated but where fabric drape and handle is not sacrificed. Knitted fabrics, for example, are thus free of any tendency to ladder when one of the knitted loops therein is broken.

Yarns consisting of or containing composite fibres may be. utilised in the manufacture of laid or woven scrims which are employed, for example, for the reinforcement of sheets of plastic. The use of composite fibres in the making of scrims greatly simplifies the manufacturing operation. For example, bonding of the laid or woven structure can be accomplished simply by the application of heat and pressure and thus the necessity for using a heat sensitive warp size or dipping the structure in an adhesive before bonding on the loom is eliminated.

In a particularly useful embodiment of this invention the fibrous structures in the form of fibrous webs are employed in the production of nonwoven fabrics.

The fibrous web from which the nonwoven fabrics are derived may be prepared by a variety of methods, and the method selected in a particular instance, depends to a very large extent on the length of the fibres when fibres other than continuous filaments are used.

Staple fibre webs may be prepared, for example, by a Woollen or cotton carding machine or a garnetting machine which result in a web in which the staple fibres are oriented predominately in one direction. The thin web obtained from a single card or garnet may be used by itself but sometimes it is necessary and desirable to superimpose a plurality of such webs to build up the web to a sufiicient thickness and uniformity for the end use intended. In building up such a web, alternate layers of carded webs may be disposed with their fibre orientation directions disposed at a certain angle, convenient y 90, with respect to intervening layers. Such cross-laid webs have the advantage of possessing approximately the same strength in at least two directions. Furthermore cross lapping in this manner provides a product having a balanced stretchability. Random or isotropic staple fibre webs may be obtained, for example, by air-laying staple fibres. Thus, one staple fibre web suitable for use in the process of this invention may be obtained by feeding continuous filaments to a cutter or breaker which discharges the fibres into an air stream produced by the blower. Suitable conduits are provided to guide a suspension of the staple fibres in a current of air to a foraminous surface on which the fibres settle as an interlaced and matted layer preferably being encouraged to do so by the application of suction on the other side of said surface. The foraminous surface can be in the form of an endless belt which is caused to travel past the place at which the fibres are fed .to it, so as to form a continuous layer of indefinite length. Instead of having a travelling flat screen, a stationary formed screen may be used for the formation of shaped articles. For example, it may take the form of a hat-shaped cone such as is used in the hatting trade. Alternatively, it may have any other form suitable for producing the desired shape of the bonded nonwoven fabric of this invention. A method of making a web containing fibres of a shorter length, say 0.5 inch or shorter,

them onto a collecting surface where they accumulate in overlapping layers, the individual filaments in each layer being predominantly coplanar, lying parallel or substantially parallel to the collecting surface and to the bottom and top of the web so formed.

Conveniently, the step of web formation is accomplished by mechanical means, such as forwarding jets,

which may be operated to lay the filaments down at random or in some desired pattern. The collecting surface may be rotated or oscillate to produce even accumulation of the filaments, and amoving belt may be used as the collecting surface and in one embodiment of this'invention described more fully hereinafter the continuous filament web is laid directly onto a moving belt.

A convenient method for preparing a continuous filament web in which the filaments are multifilaments is disclosed in British Pat. No. 1,088,931.

If desired the fibrous web maybe needle-punched on a conventional needle loom and/or a light woven scrim may be incorporated therein.

As stated hereinbefore the bonded structures of the present invention have advantages in terms of drape and handle over prior art structures and this is particularly the case with non-woven fabrics. Thus for a given fabric strength fabric densities can be much reduced with-consequent improvements in drape whilst the absence of any binder spread also improves the handle of the fabrics. The advantages can be clearly seen from the accompanying drawings wherein;

FIG. 1 is a graph comparing physical characteristics'of a bonded textile material of this invention with those of a prior art bonded textile material;

FIG. 2 is a photomicrograph illustrating the effect of heat and pressure on, and the type of bond formed by, the composite fibres of this invention;

FIG. 3 is a photomicrograph illustrating the effect of heat and pressure on fibres used in the manufacture f prior art bonded textile materials;

FIGS. 4A and 4B are enlarged schematic representatrons of microscopic observations of the effect of heat and pressure on fibres used in the manufacture of prior art bonded textile materials; and

FIG. 5 is a photomicrograph of a fragmentary section of a nonwoven fabric according to one embodiment of this inventlon.

The superior properties of the nonwoven fabrics derived from composite fibres is clearly illustrated in the graph shown in FIG. 1 of the accompanying drawing wherein tensile strength in kg./gm./cm. is plotted against density in gm./cm. and which is based on measurements of the tensile strength at various densities of two nonwoven fabrics, one of which was derived from a fibrous web of polyhexamethylene adipamide/poly(omega-aminoundecanoic acid) composite fibres, the components being arranged side-by-side and the other from a fibrous web which comprised a blend of polyhexamethylene adipamide fibres and poly(omega-- aminoundecanoic acid) fibres the latter fibres being present in amount by weight equivalent to the amount of composite fibres in the outer web and each web being activated and bonded by heating under pressure to prevent crimping of the composite fibres The photomicrographs of FIGS. 2 and 3 and the diagrammatic representations of FIGS. 4A and 4B in the accompanying drawings permit a comparison of the effect of heat activation and pressure on, and the type of bond formed by, composite fibres and the thermoplastic fibre binders of the prior art.

Referring to FIG. 2, the photomicrograph shows the type of bond formed at a temperature of 240 C. and under pressure between two composite fibres 11 and 12 in the form of twelve denier staple, each consisting of two components 13 and 14 arranged in a side-by-side relationship. Component 13 is polyhexamethylene adipamide while component 14, the potentially adhesive component, is polyepsilon caprolactam. From the figure, it can be seen that the uncrimped composite fibres 11 and 12 are bonded to one another at cross-over point 15 by a spot bond 16 which results from the adhesive characteristics of the polyepsilon caprolactam component of each composite fibre developed by heat. The bond also exhibits a high degree of self-bonding, by which I mean that, at the cross-over point 15, the polyepsilon caprolactam component of one composite fibre traverses the polyhexamethylene adipamide component of the other and fuses with the polyepsilon caprolactam component of that other composite fibre. It will be observed that, despite the temperature and pressure conditions to which the composite fibres are subjected, the polyepsilon caprolactam component 14 remains in contiguous association with the polyhexamethylene adipamide component 13 and the open spaces 17 between the filaments are characterised by the absence of any potentially adhesive component.

FIGS. 3 and 4A and 4B illustrate the effect of heat and pressure on fibres which constitute the fibrous web used -in the manufacture of the nonwoven fabrics described -240 C. under pressure. In the photomicrograph of FIG. 3, which shows in isolation two fibres from the heated and pressed fibrous web, reference numeral 18 designates a 6 denier polyhexamethylene adipamide staple fibre and reference number 19 a 12 denier polyepsilon caprolactam staple fibre. Under the conditions of temperature and pressure to which the fibres are subjected, the polyepsilon caprolactam fibre melts, loses its shape and identity as a fibre and forms blobs. The commencement of the deformation of the polyepsilon caprolactam fibre 19 in this manner is shown in the photomicrograph wherein the blobs are designated by the reference numeral 20.

FIGS. 4A and 4B are schematic representations of microscopic observations of the effect of temperature and pressure on the fibrous web described in Britist Pat. No. 887,906. In FIG. 4A which shows the behavior of the fibres at a temperature of approximately 200 C. and under a moderate pressure, reference numeral 21 designates polyhexamethylene adipamide fibres and 22 a polyepsilon caprolactam fibre. It will be observed that the polyepsilon caprolactam has retained its identity as a fibre but I shows the behavior of the fibres at a temperature of approximately 250 C. under a moderate pressure and it can be seen that the polyepsilon caprolactam fibre has melted, lost its fibrous shape and identity, and flowed along the polyhexamethylene adipamide fibres 21 to form numerous blobs 24. At somewhat higher temperatures the polyepsilon caprolactam, as the molten polymer, spreads freely through the interstitial spaces in the fibrous web, forming blobs of polymer through the structure.

The difference in behavior on heating and pressing between fibrous webs containing composite fibres and those prior are fibrous webs containing thermoplastic binder fibres (for example the fibrous web utilised in British Pat. No. 887,906) is reflected, at a subjective level, in the handle and general appearance of the nonwoven fabrics derived from those webs. Thus, the nonwoven fabrics de rived from the fibrous webs described in the specification of the aforementioned British patent and prepared by the process disclosed therein possess, on account of the presence of numerous blobs of molten polymer throughout the sturcture, a more or less harsh handle and are frequently palpably rough. The nonwoven fabrics of my invention frequently have a softer and better developed textile-like handle.

The photomicrograph of FIG. 5 in the accompanying drawings shows a portion of the fabric derived from a carded web consisting of 10 percent by weight of two inch 12 denier per filament staple fibres formed from composite fibres consisting of equal proportions by weight of polyhexamethylene adipamide and an /20 random copolymer of polyhexamethylene adipamide/polyepsilon caprolactam, the two components being arranged in a side-by-side relationship, and percent by weight one and half inch 3 denier non-activatable polyhexamethylene adipamide stable fibers. The carded web had been placed between two metal plates and maintained at a temperature of 220 C. and subjected to a pressure of 30 kg./cm. for a period of approximately one minute to prevent crimping whilst effecting bonding.

Under these conditions of temperature and pressure the adhesive characteristics of the copolymer component 26 of the composite fibre 25 were developed and refined were formed between that component and the non-activatable polyhexamethylene adipamide fibres 28 at the points of contact 29. Despite the activation and bonding treatments to which the web was subjected the copolymer component remains in contiguous association with the polyhexarnethylene adipamide component 27 which retained its fibrous form. The absence of any spread of the potentially adhesive component throughout the structure and the refined nature of the bonds formed results in preservation of substantially all the interstitial spaces 30 between fibres.

The fabric had an excellent tensile strength, a useful porosity, a smooth and pleasant handle and surfaces which were free from irregularities due to blob formation.

The nonwoven fabrics of this invention have a wide range of appearances and properties ranging from crisp paper-like structures to drapable fabric-like, or hard boardlike to more bulky felt-like structures. The density and porosity of the fabrics is controlled by the pressure if any under which they are formed, and as a general rule, the higher the pressure-the harder and less porous the fabric.

The nonwoven fabrics have a wide range of uses. As examples of some of these uses there may be mentioned their use as an industrial fabric in heat, sound and electrical insulation, as floor-coverings, in the filtration of gases and liquids, as apparel fabrics in the manufacture of hats, caps, jackets and other articles of clothing and as interlinings for suits and coats, and as household fabrics, for a variety of upholstery purposes. They may also be used as a base to which various coating compositions may be applied to form sheet or shaped materials of improved properties.

Some of the bonded textile materials provided by this invention and the process for manufacturing them will now be illustrated in the following examples which are not to be regarded as in any way limitative of the scope of the invention.

' EXAMPLE 1 A quantity of one and a half inch 12 denier stable fibre formed from oriented polyhexamethylene adipamide/ poly(omega-aminoundecanoic acid) (nylon 66/11) composite fibres in which the two components were present in equal proportions by weight and in a side-by-side relationship, was carded into a loose fibrous web which was then placed between heated platens maintained at 210- 220 C. and subjected to a pressure of 700 gm./cm. for seconds. The resulting fabric in which the composite fibres were not helically crimped resemble a felt in appearance, had a useful textile-like handle, was free from blobs and possessedconsiderable strength. A blend of equal proportions by weight of one and half inch 6 denier stable fibres of polyhexamethylene adipamide and poly- (omega-aminoundecanoic acid) was carded into a loose web identical to that obtained with the composite fibres and was subjected to the same bonding treatment. The

' nonwoven fabric derived from this fibrous web had a harsh and hard handle, and was palpably rough due to the presence of numerous blobs resulting from deformation of the poly(omega-aminoundecanoic acid) fibres. The strength of the two fabrics was determined in an Instron Tensile Tester by clamping a two inch wide sample between the jaws of the tester'which were set five cms. apart and elongating the sample at a rate of 10 cm./min. i.e. 200 percent per minute at a temperature of 21 C. and a relatively humidity of 60 percent. The strengths and other physical properties of the two fabrics are shown in the table below:

Weight per unit Break- Exten- Density length of ing slon to Tensile of fabric fabric, load, break stren th, Sample gm./em. gm./em. kg. percent kgJgmJ cm Composite fibre 0. 31 0. 054 32 28 592 Blend 0. 41 0. 053 29 36 548 The nonwoven fabric formed from the composite fibres was therefore stronger for a given density than the fabric formed from the blend of filaments.

EXAMPLE 2 Th process of Example 1 was repeated except that the webs were subjected'to a pressure of 2x10 gm./cm. for seconds. The fabric formed from the composite fibres was harder and less porous than the obtained in Example 1. Details of the strength and other physical properties possessed by the fabrics are given below:

In this instance the fabric formed from the composite fibres were some 34 percent stronger than that obtained from the blended staple and it had a better developed textile-like handle and appearance.

1O EXAMPLE 3 Continuous filaments consisting ofequal proportions by weight of polyhexamethylene adipamide and an /20 random copolymer of polyhexamethylene adipamide/ polyepsilon caprolactam (nylon 66/ 66/ 6) the two components being arranged in a side-by-side relationship were laid into a web having a weight of 5 ounces per square yard :by the spraying technique described in our British Pat. No. 1,088,931.

A six inch square portion of this web was placed between two pieces of 18 mesh brass gauze maintained at temperature of approximately 220-230 C. and subjected to a pressure of 5 kgms./cm. for a period of two minutes..The product was bonded nonwoven fabric in which the composite fibres were not helically crimped possessing a textile-like handle and a useful drape or flexibility with the pattern of the gauge embossed on the surfaces which were free from blob formation. As regards appearance the product was somewhat similar to a coarse woven fabric.

The strength of the fabric in the longitudinal and transverse directions was measured on samples 6 inches long and 2 cms. wide, which were clamped between the jaws of an Instron Tensile Tester, the jaws of which were set 5 cms. apart. The samples were elongated at a rate of 5 ems/min. i.e. percent per minute at a temperature of 21 C. and a relative humidity of 60 percent.

Details of the strength and other physical properties possessed by the fabric are listed in the table below:

Denisty, gmJcm. 0.28 Weight per unit length, gm./cm 0.0408 Breaking load, kg 9.1 Extension to break, percent 91 Tensile strength, kg./gm./cm. 223

EXAMPLE 4 Continuous filaments consisting of equal proportions by weight of polyhexamethylene adipamide and po1y(omegaaminoundecanoic acid) (nylon 66/11) the two components being arranged in a side-by-side relationship were laid into a web having a weight of 6 ounces per square yard by the spraying technique described in British Pat. No. 1,088,931. A portion of this web was placed between two flat aluminium sheets, the contacting surfaces of which were coated with polytetrafluoroethylene, maintained at a temperature of 210 C. and subjected to a pressure of 21 kgms./cm. for'a period of one minute. The product had the smooth surface and general appearance of a paper sheet, to which it also had an afiinity in respect of handle and the composite fibres contained no helical crimp. Its drapable and crease-resistant character made it very suitable for use as a coat or suiting interliner. Various properties of the sheet were then determined on a sample thereof. The tensile strength in this and the following examples was measured by the procedure outlined in Example 3 above. Details of the measurements and properties are listed in the table belows:

Density, gm./cm. 0.80

Weight per unit length, gm./cm. 0.0374 Break load, kg. 13.5 Extension to break, percent 46 Tensile strength, kg./gm./cm. 361

EXAMPLE 5 staple in a Dorstling flock cutting machine. A ten gm.

quantity of this staple was dispersed, by vigorous agitamaintained at a temperature of 230 C. and subjected to a pressure of 27 kgs./cm. for a period of one minute, to give a fabric having the appearance and crisp handle of a smooth paper sheet in which the composite fibres had no helical crimp. The fabric had a density of 0.25 gm./cm. and a tensile strength of 450 kgs./gm./cm.

EXAMPLE 6 A quantity of two and a half inch 6 denier staple fibre formed from composite fibres consisting of equal proportions by weight of polyhexamethylene adipamide and an 80/20 random copolymer of polyhexamethylene adipamide/polyepsilon caprolactam (nylon 66//66/6), the two components being arranged in a side-by-side relationship, was carded on a Shirley miniature carder and the laps so formed laid on top of each other with successive laps disposed at an angle of 90 with respect to the previous lap so forming a cross-laid web having a weight of ounces per square yard. The web was then placed between two twenty mesh zinc gauzes maintained at atemperature of 235 C. and subjected to a pressure of 40 kgs/cm. for a period of two minutes. The product was strong and resilient with the general appearance of a hard thick felt and in which the composite fibres had no helical crimp. The gauze pattern was reproduced on the surfaces of the product to give a decorative effect.

A sample of the sheet had the following properties:

Density, gm./cm. 0.45 Weight per unit length, gm./cm. 0.126 Breaking load, kg. 66.0 Extension to break, percent 8 Tensile strength, kg./gm./ cm. 524

EXAMPLE 7 A quantity of two and a quarter inch 6 denier staple fibres formed from composite fibres consisting of equal proportions by weight of polyhexamethylene adipamide and poly (omega-aminoundecanoic acid) (nylon 66/ 11) components arranged in a side-by-side manner was blended with a quantity of non-activatable polyhexaethylene adipamide two inch 3 denier staple fibres in a 60/40 ratio by weight. A portion of this blend was thereafter carded using a Shirley miniature carder and the laps so formed laid on top of each other with successive laps disposed at an angle of 90 with respect to the previous lap so forming a cross-laid web having a weight of approximately 12 ounces per square yard. The web was then placed between two aluminium plates, the contact surfaces of which were coated with polytetrafiuoroethylene, maintained at a temperature of 230 C. and subjected to a pressure of 40 kgsjcm. for a period of 1 minutes. The resulting self-supporting sheet had a smooth surface substantially free from any irregularities due to blob formation, was flexible enough to have a useful drape and good crease-resistance properties. It had a softer handle and a greater porosity than a sheet derived from fibrous web containing 100 percent com- 12 posite fibres and its composite fibres had no helical crimp. Various properties of this sheet were then determined on a sample 6 cm. long and 2 cm. wide and the results are listed in the following table:

Density, gm./cm. 0.35

Weight per unit length, gin/cm. 0.0647

Load to break, kg. 36.7

Extension to break, percent 6 Tensile strength, kg./gm./cm. 567

EXAMPLE 8 A quantity of two inch 6 denier staple fibres having the same composition as those used in Example 6 was carded on a Shirley miniature carder and the laps so formed cross-laid to give a web having a weight of 14 ounces per square yard. The web was then placed between two 4 mesh zinc gauzes maintained at a temperature of 230 C. and subjected to a pressure of 30 kg. for a period of 1 minute. The product was a self-supporting patterned fabric in sheet form in which the composite fibres had no helical crimp and which had the following properties:

Density, gm./cm. 0.13 Weight per unit length, gm./cm. 0.0276 Breaking load, kg. 8.1 Extension to break, percent 4 Tensile strength, kg./gm./cm. 294

EXAMPLE 9 15 gms. of two inch 3 denier staple fibres, white in colour and formed of composite fibres consisting of equal proportions by weight of polyhexarnethylene adipamide and an /20 random copolymer of polyhexamethylene adipamide and polyepsilon caprolactam, the two components being arranged in a side-by-side relationship was blended with 15 gms. 3 denier polyhexarnethylene adipamide staple fibres. Of the 15 gms. of the non-activatable polyhexamethylene adipamide staple fibres, 6 gms. were coloured yellow, 3 gms. orange, 3 gms. green, 2 gms. red and 1 gm. blue. The blend was then carded using a Shirley miniature carder to form a fibrous web. A portion of this web was placed between two 20 mesh zinc gauzes maintained at a-temperature of 230 C. and subjected to a pressure of 20 kgs/cmfi. for a period of 1 minute. The product resulting from this activation and bonding treatment was a nonwoven fabric having pleasant and decorative random coloured effects and an appearance which was similar in many respects to a coarse woven fabric the constituent composite fibres being free from helical crimp. The product was eminently suitable for use as an upholstery fabric. It had the following properties:

Density, gmJcm. 0.32

Weight per unit length, gm./cm. 0.0236

Breaking load, kg. 13.0

Extension to break, percent 22 Tensile strength, kg./gm./cm. S53

EXAMPLE 10 10 gms. of two inch 6 denier staple fibre formed from composite fibres having the same composition and arrangement of components as those used in Example 1 were blended with 10 gms. of one and a half inch cotton staple fibres. The blend was then carded using a Shirley miniature carder and the web so formed placed between two aluminium plates, the contacting surfaces of which were coated with polytetrafluoroethylene, maintained at a temperature of 215 C. and subjected to a pressure of 35 kgsJcm. for a period of 1 minute. The product was a nonwoven fabric with the general appearance of a smooth sheet of paper and had a crisp handle the constituent composite fibres being free from helical crimp. A number of properties, details of which are given in table below were then determined on a sample of the fabric:

Tensile strength of this fabric and those produced in Examples 11 to 17 which follow was measured along the card direction.

EXAMPLE 11 ing surface of which was coated with polytetrafluoroethylene) and a 20 mesh zinc gauze, maintained at a temperature of 220 C. and subjected to a pressure of 25 kgs./cm.

for a period of three-quarters of a minute. One surface of the resulting paper-like fabric was smooth while the other reproduced the pattern of the gauze the constituent fibres being free from helical crimp. The fabric had the following properties:

Density, gm./cm. 0.27

Weight per unit length, gm./cm 0.0169

Breakingload, kg. 3.3

Extension to break, percent 15 Tensile strength, kg./gm./cm. 194

EXAMPLE 12 A quantity of two inch 6 denier staple fibres formed from composite fibres having the same composition and arrangement of components as in Example 1 was blended with a quantity of two inch 3 denier non-activatable polyhexamethylene adipamide staple fibres in a 60/40 ratio by weight. A portion of this blend was carded using a Shirley miniature carder into a loose fibrous web having a weight of approximately 4 ounces per-square yard. A portion of this web was then placed between two aluminium plates, the contacting surfaces of which were coated with polytetrafiuoroethylene, and heated in a hydraulic press under a pressure of 28 kgs./cm. for a period of one minute at a temperature of 220 C. A thin paper-like fabric which had the following properties was produced, the constituent composite fibres being free from helical crimp.

Density, gm./cm. 0.33 Weight per unit length, gm./cm. n 0.0224 Breaking load, kg. 15.7 Extension to break, percent 24 Tensile strength, kg./gm./cm. 704

EXAMPLE 13 A carded web as in Example 12 but composed of 20 percent by weight of the composite fibres and 80 percent by weight of the non-activatable polyhexamethylene adipamide fibres was heated in a hydraulic press between two 20 mesh zinc gauzes under a pressure of 25 kgs./cm. for a period of one minute at a temperature of 225 C The product formed in which the constituent composite fibres were free from helical crimp was a fabric having a pleasant, soft textile-like handle with the general appearance of a somewhat stilt woven fabric. It dyed uniformly with only one dyestuff and was washable. The

fabric was very suitable for use as an interlining fabric. It had the following properties:

Density, gm./cm. 0.21

Weight per unit length, gun/cm. 0.0233

Breaking load, kg. 6.9

Extension to break, percent 20 Tensile strength, kg./gm./cm. 296

EXAMPLE 14 A quantity of two and a half inch. 3 denier staple fibres formed from composite fibres having the same composition and arrangement of components as those of Example 9 was carded using a Shirley miniature carder into a loose fibrous web having a weight of 4 ounces per square yard. A second web having a weight of 4 ounces per square yard was prepared in a like manner from a blend consisting of equal quantities by weight of the same composite fibres and two inch 3 denier non-activatable polyhexamethylene adipamide staple fibres. 10 gms. of the staple fibres in this web were white, 10 gms. orange, 4 gms. red, 3 gms. blue and 3 gms. yellow.

The first web was then laid on top of the coloured web to form a composite web in which the carded directions of the two webs were the same. This composite structure was then placed between an aluminium plate and a 20 mesh zinc gauze maintained at a temperature of 225 C. and subjected to a pressure of 40 kgs./ 0111. for a period of l /z minutes.

The product was a reversible bi-coloured type fabric with one surface having the appearance and handle of a coarse woven fabric and pleasantly coloured in a random manner and the other surface essentially white with a smooth and soft handle. The colured surface was basically orange-red flecked with blue. The fabric showed little tendency to delaminate, had a good abrasion resistance and its constituent composite fibres had no helical crimp. It was very suitable for use as an upholstery fabric. lit had the following properties:

Density, gm./cm. 0.38 Weight per unit length, gm./ cm 0.0542

Breaking load, kg 32.8 Extension to break, percent 36 Tensile strength, kg./gm./cm. 605

EXAMPLE 15 staple fibre formed from polyhexamethylene adipamide and an =/20 random copolymer of polyhexamethylene adipamide and polyepsilon caprolactam (nylon 66/ 66/ 6) in which the two components were present in equal proportions by weight and in a side-by-side relationship. The blend was then carded using a Shirley miniature carder and an 18 inch long and 12 inch wide portion of the loose. fibrous web formed was placed between an aluminium plate (the contacting surface of which was coated with polytetrafiuoroethylene) and a 20 mesh zinc gauge maintained at a temperature of 225 C. and subjected to a pressure of 25 kgs./cm. for a period of 1 minute. The product was resilient nonwoven fabric, one surface of which was patterned and resembled a woven fabric and the other surface was smooth with a soft handle.

The fabric had good abrasion and crease-resistance properties which rendered it very suitable for use as an interlining fabric and its constituent composite fibres had no helical crimp.

Tensile strength, kg./gm./cm.

15 Some of the physical properties possessed by the fabric are listed in the table which follows:

EXAMPLE 16 A quantity of two inch 12 denier staple fibres formed from composite fibres having the same composition and arrangement of components as in Example 1' was carded using a Shirley miniature carder into a loose fibrous web having a Weight of 4 ounces per square yard. A 12 inch long, and 9 inch wide portion of this web was then passed at a rate of 1 foot per minute between the nip of two calender rollers each 4 inches in diameter and which exert a pressure of approximately 10 kg./cm. The temperature of the calender rolls was of the order of 240 C. The fabric produced :by this process had the appearance and crisp handle of a smooth paper sheet. It had a porous, relatively open structure and its constituent composite fibres had no helical crimp.

Some of the physical properties possessed by the fabric are listed in the table which follows:

Density, gm./cm. 0.28 Weight per unit length, gm./cm 0.0248 Breaking load, kg. 7.6 Extension to break, percent 18 EXAMPLE 17 A quantity of two and a half inch 3 denier staple fibres formed of composite fibres having the same composition and arrangement of components as those used in Example 1 was blended with a quantity of non-activatable polyhexamethylene adipamide two inch 3 denier stable fibres in a 60/40 ratio by weight. The blended fibres were carded using a Shirley miniature carder and the laps so formed cross-laid to give a loose fibrous web having a weight of 12 ounces per square yard. A portion of this web was then placed between two perforated zinc sheets, the perforations (30 in a square inch) being arranged therein in a regular manner, maintained at a temperature of 225 C. and subjected to a pressure of 30 kgsjcrnl. for a period of 1 minute. During this period, the zinc plates were moved relative to one another over each surface of the fibrous web. The surfaces of the nonwoven fabric produced by this process carried interesting and decorative surface eifects. These varied from clusters of small rosettes to large hexagonal patterns. This patterned effect gave the fabric an appearance not unlike that of conventional moir fabric.

The fabric which was useful for upholstery purposes had the following physical properties and its constituent composite fibres had no helical crimp.

' Density, gun/cm. 0.14 'Weight per unit length, gm./cm 0.0180 Breaking load, kg 7.0 Extension to break, percent 19 Tensile strength, kg./gm./cm. 389

EXAMPLE 18 This example and those which follow illustrate methods for making scrim fabrics from yarns containing continuous composite fibres.

Yarn having a denier of 1610 and containing 117 con tinuous composite fibres consisting of equal proportions by weight of polyhexamethylene adipamide and an 80/20 random copolymer of polyhexamethylene adipamide and polyepsilon caprolactam arranged side by side and having a breaking load of 9.1 kg. was made up on a wire frame into a woven net-like structure having 3 ends per inch and 3 picks per inch.

The structure was then placed between two Teflon coated aluminium sheets and heated in a hydraulic press under a pressure of 10 kgs./cm. at a temperature of 220 C. for a period of 3 minutes.

Under the conditions of temperature and pressure the copolymer component of the composite fibres was activated and formed bonds at the points of contact of the weft and warp yarns, but the composite fibres was prevented from crimping helically.

The coherent scrim fabric produced was enimently suit able for use as a reinforcement material for plastic, for example, polyvinyl chloride, sheets.

' The mean bond strength, measured on the Instron Tensile Tester by the procedure described in Example 3, was 800 gms. and the fabric had a breaking load of ap proximately 13.4 kgs. per inch.

EXAMPLE 19 proximately 15 kgs. per inch, the composite fibres being free of helical crimp.

EXAMPLE 20 A net-like fabric was woven with 3 ends per inch and 3 picks per inch from the following yarns:

Warp yarnMultifilamentous yarn consisting of polyhexamethylene adipamide of 1680 denier and containing 272 filaments.

Weft yarn-As the yarn in Example 18.

The woven structure was placed between two Teflon coated aluminium sheets and heated in a hydraulic press under a pressure of 30 kgs./cm. at a temperature of 220 C. for a period of 3 minutes.

The resulting bonded scrim fabric had a mean band strength of 61.5 gms. and the breaking load of the fabric in the weft direction was approximately 13.8 kg. per inch, the constituent composite fibres being free from helical crimp.

EXAMPLE 21 Example 18 was repeated using yarn having a denier of 360 and containing 24 continuous composite fibres consisting of equal proportions by weight of polyhexamethylene adipamide and a 60/40 random copolymer of polyhexamethylene adipamide and poly-epsilon caprolactam,

EXAMPLE 22 A quantity of two and -a half inch 18 denier staple fibre formed from composite fibres having a concentric coresheath composition, consisting of equal proportions by weight of polyhexamethylene adipamide as core and polyeps ilon caprolactam as sheath was carded on a Shirley miniature carder and the laps so formed laid on top of each other with successive laps disposed at an angle of with respect to the previous lap to form a cross-laid web having a weight of approximately 10 ounces per square yard. The web was then treated in an atmosphere of air/ steam, at a temperature of 225 C. for approximately 16 seconds, without application of pressure to the web. Immediately on leaving the heating zone the bonded web was subjected to a pressure of about 2 kg/crn. to yield a material having the following properties:

The resulting self-supporting fabric was suitable for A carpet underlay, air filters, interlinings and so on, and its fibres were free of helical crimp.

EXAMPLE 23 A quantity of one and a half inch 3 denier staple fibres formed from composite fibres having a concentric coresheath arrangement of components, consisting of 75% by weight of polyhexamethylene adiparnide (nylon 6.6) as core, and 25% by weight of an 80/20 random copolymer of polyhexamethylene adipamide/polyepsilon caprolactam (nylon 6.6/ 6) as sheath wasprepared. This was blended with an equal quantity of one and a half inch 3 denier staple fibres of non-activatable polyhexamethylene adipamide (nylon 6.6). The blend was carded on a Shirley miniature carder and the laps so formed laid on top of each other with successive laps at 90 with respect to the previous lap to form a cross-laid web. The web was treated in an oven at 235 C. for 16 seconds as in Example 22 and subjected'to a pressure of 2 kg./cm. immediately on leaving the oven. A self supporting fabric, suitable for interlinings was formed, in which the fibres had no helical EXAMPLE 24 This example illustrates the improved tensile properties of fibrous structures manufactured from composite fibres containing a potentially adhesive component over fibres coated with non-fibre-forming binder material prior to forming the fibrous structure, as known in the prior art.

A web was made from composite symmetrical coreand-sheath continuous filaments by deposition from an air gun traversing across a moving conveyor. The fila- -ments consisted of 89.5% polyhexamethylene adiparnide (nylon 66) as core, and 10.5% of a 70/30 random copolymer of polyhexamethylene adipamide/polyepsilon caprolactam (nylon 66/ 6). One filament of this composite structure was passed through an air gun traversing at 24 cycles per minute with a 30" stroke, at a height of 30" above an earthe d conveyor, which was advancing at 0.2 ft./min. perpendicularly to the direction of traverse of the air gun. In this fashion a web of composite fibres containing a potentially adhesive component was fabricated, referred to in this Example as Web A.

A second web was made, consisting of 100% polyhexamethylene adiparnide (nylon 66) on to which a solution of non-fibre-forming adhesive was sprayed 9 feet above the traversing air gun. The non-fibre-forming adhesive had the following constituency when sprayed:

Parts Polyvinyl chloride (binder) 100 Dioctyl sebacate (plasticiser) 100 Methyl ethyl ketone (solvent) 2000 The filaments so formed were found to consist of a core of polyhexamethylene adiparnide surrounded by a concentric sheath of polyvinyl chloride. A web was fabricated using the same apparatus as the Web A above, and-this web is referred to in this Example as Web B.

Portions of Web A and Web B were pressed between silicone release papers at 500 lbs./ sq. in. at a temperature of 175 C. for five minutes to effect interfilamentary bonding in the web, and the resulting bonded structures were tested for strength.

Breaking Density, Web weight stren th,

Web A" 0. 43 24. 3 280. 0 0. 45 38. 3 20. 5

Web B Web A which was manufactured from composite fibres containing a potentially adhesive component, according to the present invention, was found to have considerably greater breaking strength than Web B which contained a non-fibre-forming sheath according to the prior art, and the fibres of both webs were substantially free from helical crimp.

I claim:

1. A bonded textile material of a fibrous character comprising at least five percent, based on the weight of fibres in the material, of composite fibres substantially free of helical crimp which fibres consist of at least two fibre-forming synthetic polymer components arranged in distinct zones across the cross-section of each fibre, said composite fibres having the ability to form a helical crimp upon activation of the self-crimping properties of the fibres, at least one but not all of which components is potentially adhesive and located in said fibres so as to form at least a portion of the peripheral surface thereof, the fibres in said material being bonded where they are in contiguous relationship by the adhesive characteristics of said potentially adhesive component.

2. A bonded textile material according to claim 1 wherein the material is in the form of a nonwoven fabric having a density of at least 0.1 gm./cm.

3. A bonded textile material according to claim 1 wherein composite fibres are present in an amount of between 20 to percent, based on the weight of the fibres in the material, and the balance, if any, are nonactivatable fibres.

4. A bonded textile material according to claim 3 wherein the non-activatable fibres are wool, cotton, viscose rayon or synthetic polymer fibres.

5. A bonded textile material according to claim 1 wherein the composite fibres contain only two components.

' 6. A bonded textile material according to claim 5 wherein the two components of the composite fibres are arranged in a side-by-side relationship.

7. A bonded textile material according to claim 5 wherein the potentially adhesive component completely surrounds the other component.

8. A bonded textile material according to claim 5 wherein the components are polyamides, polyesters, polyesterarnides, polysulphonamides, polyolefins, polyurethanes or copolymers thereof.

9. A bonded textile material according to claim 8 wherein the two components comprise dillerent polyamides.

10. A bonded textile material according to claim 9 wherein the potentially adhesive component is poly(omegaaminoundecanoic acid) and the other component is polyhexamethylene adiparnide.

11. A bonded textile material according to claim 9 wherein the potentially adhesive component is a copolymer of polyhexamethylene adiparnide and polyepsilon caprolactam and the other component is polyhexamethylene adiparnide.

12. A process for making bonded textile materials which comprises forming a fibrous structure containing at least five percent by weight of composite fibres which consist of at least two fibre-forming synthetic polymeric components arranged in distinct zones across the cross section of each fibre, said composite fibres having the ability to form a helical crimp upon activation of the selfcrimping properties of the fibres, at least one but not 19 all of which components is potentially adhesive and located in said fibres so as to form at least a proportion of the peripheral surface thereof and bonding the fibres together Where they are in contiguous relationship by rendering adhesive the potentially adhesive component of said composite fibres whilst said fibrous structure is under a pressure of at least 1 gun/cm. so as to prevent said composite fibres from forming a helical crimp.

13. A process as claimed in claim 12 in which the composite fibres do not possess potential helical crimp and the potentially adhesivecomponent is rendered adhesive by heating the structure.

14. A process as claimed in claim 12 in which the potentially adhesive component is rendered adhesive by chemical treatment whilst it is under a pressure of at least 1 gm./cm.

15. A process as claimed in claim 14 in which the chemical treatment comprises contacting the fibrous structure with a non-aqueous solution of formaldehyde.

16. A process as claimed in claim 15 in which the chemical treatment comprises contacting the fibrous structure with a nitric acid solution.

References Cited UNITED STATES PATENTS ROBERT F. BURNETT, Primary Examiner M. A. LITMAN, Assistant Examiner US. Cl. X.R.

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Classifications
U.S. Classification442/353, 156/308.8, 156/308.6, 442/356, 156/308.4, 442/362, 264/DIG.750, 156/181, 156/62.8, 156/296
International ClassificationD04H1/54, D04H3/14, D04H1/541, D04H3/16
Cooperative ClassificationY10S264/75, D04H1/541, D04H3/14, D04H3/16, D04H1/54
European ClassificationD04H1/541, D04H3/14, D04H1/54, D04H3/16