NO125283B - - Google Patents

Description

Non-woven fabric.

This invention relates to non-woven fabrics and relates in particular to non-woven fabrics which are similar to fleece fabrics as well as methods for the production of such.

Nonwoven fabrics in various forms have been known for many years. In the last 10 years or so, a voluminous literature has been published in this area, including many patent documents,

in connection with the production of non-woven fabrics using a technique based on needle felting of a fiber pile. Much of the effort that has gone into this particular area of non-woven fabrics, as seen in the known publications, appears to have been directed towards the production of fabrics with a felt-like appearance. Felt is a material with a dense and compact structure

with a high specific gravity, and consequently there are limited applications for which they can be used.

It is an object of this invention to produce a needle felted fabric which resembles a fleece fabric and which finds applications where fleece fabrics of the conventional type are usually applicable.

Such a fabric differs from felt in that it has a large number of fibers that extend outward in the form of floss or fiber bundles from the surface of a base or basic structure. It is these floss or fiber bundles that give the fleece its surface.

It is another object of the invention to provide a polar substance with a new structure and which exhibits advantageous properties.

A further and more special purpose of the invention is to provide a non-woven pole fabric where the pole surface is formed by fiber bundles which have good dimensional stability.

According to the invention, a non-woven fabric comprising a non-woven fiber base layer and a non-woven fiber bundle front layer is provided with the fibers from the front layer oriented through the base layer and protruding beyond its flat surface in the form of fiber bundles, at least a proportion of the fibers in at least one of the layers are composite fibers containing at least two fiber-forming synthetic, polymeric components arranged in separate zones across the cross-section of each fiber, each component being continuous in the longitudinal direction of each fiber. The substance is characterized by at least one of, but not all, the components being potentially adhesive and arranged so that it forms at least a proportion of the peripheral surface of each fiber, and the fiber bundles are fixed in the structure by means of said potentially adhesive component's adhesive properties.

In a preferred embodiment, at least a proportion of the composite fibers in at least one of the layers is crimped.

British patent 597 514 describes a felt structure (not a structure with a pole surface) which is bound together by heterofilaments with a core-sheath configuration where the sheath is a hardened plastic. The structure is therefore held together by bonds between the thermosetting plastics which, like all thermosetting plastics, are brittle. The material is therefore not stable under load, since bonds break when the material is repeatedly loaded. No such disadvantage occurs with the materials according to the invention, where the bonds are caused by a relatively flexible thermoplastic material. The composite fibers according to the British patent cannot hold a permanent ripple since the stresses which cause the ripple will gradually be relieved because the thermosetting plastic sheath will break and thus allow the stresses to be relieved.

U.S. patent 1 574 496 describes a method for the production of an unbound, non-woven fabric with pole character where the fibers are guided with needles through tightly woven material which is later torn off. Since the structure is not bound together, it will not have the stability that the substance according to the invention has. The structure according to the patent is also different from the substance in the

adhere to the invention in that it comprises a substrate of woven or knitted material and in that the surface is of pole character and not with fiber bundles.

U.S. patent 1 726 634 describes a structure with a pole surface attached by means of needles through a woven material. The structure may be bonded, but not with composite fibers.

U.S. patent 2 970 365 requires the use of an adhesive laq. The adhesive layer can be compared to a reinforcing cover, as it not only binds the fibers in the felt together, but also makes the product rigid. In contrast to this, the product according to the invention has no layer of adhesive, but is bound together throughout the structure at a number of points where the adhesive component in the composite fibers comes into contact.

The polyesters according to the invention can be produced by

using a method which involves forming a composite structure consisting of a first layer of fibers in the form of the fiber bundle front layer, a second layer of fibers in the form of the base layer and needle felting the composite structure in a needle felted chair, whereby fibers are led from the front layer through the base layer out past its flat surface from which they protrude in the form of fiber bundles, after which the needle felted product is subjected to at least one treatment to fix the fiber bundles.

A particularly suitable method for fixing the fiber bundles in position is to introduce in either the base layer or the fiber bundle front layer, respectively in both, fibers with latent curling ability if curling develops after the needle felting operation. When it is the base layer that is provided with fibers with latent curling ability, the fixation of the fiber bundles, which takes place during the

calling the ripples in the fibers in the base layer, the fiber looping and interlocking caused by deformation of the fibers as they are rippled. In addition to fixing the fiber bundles in position, fiber

the entanglement also increase the mechanical strength and stability of the fabric. Furthermore, the presence of crimped fibers in the base layer will give the fabric good volume or fullness, which is particularly valuable when the fabric is to be used as a material for floor coverings.

When the fiber bundle front layer is provided with fibers with latent shrinking ability, the fixation of the fiber bundles, which takes place in this layer, is due to their transformation from straight branched structures to mushroom-shaped structures during the development of the ripples. The longitudinal contraction associated with the development of the ripples increases the locking effect of the fiber bundles and thereby fixes them more firmly in position. Furthermore, the transformation of the fiber bundles into a mushroom-like structure where each bundle ends in the form of a bell-shaped cap will spread the fiber bundles over the surface and thereby provide more effective coverage of the underlying fiber base layer.

Although the fiber bundles in such non-woven fabrics, where the fibers have been crimped after the needle felting operation, are held relatively well in position, it is often advantageous to further fix the fiber bundles in the fabric. According to a preferred embodiment of the invention, the fiber bundles are further fixed by means of a treatment which results in direct or indirect binding of the fibers in the base layer. As a result of this bonding, the roots of the fiber bundles, i.e. the vertically arranged fibers embedded in the base layer, are fixed in position and consequently the fiber bundles are fixed in their needle felted formations, whereby the resulting nonwoven fabric has an improved flossing or shear strength.

Both the base layer and the fiber bundle front layer can be composed of one fiber pile or several fiber piles arranged on top of each other. The fiber web may be made from any fibers, natural or synthetic, suitable for use in the manufacture of nonwovens. In those cases where the fiber bundles are fixed by the development of ripples which are latent in the fibers in the base layer or the fiber front layer or both, it is however necessary to supply the layer or layers with a proportion of such fibres. When such fibers are present in one or both layers, it should generally amount to at least 10% by weight based on the total weight of fibers in the layer. Although a number of different synthetic filaments can be produced which have the ability to curl when properly heated, they are more or less desirable for use in accordance with the present invention. Especially composite fibres, i.e. fibers which contain two or more components arranged side by side in relation to each other in the longitudinal direction and which have latent frizziness due to their structure, are suitable for use according to the present invention. The composite fibers can preferably contain at least one component that can be made adhesive under conditions that do not significantly affect it. other component or components, as this potentially adhesive component (occupies at least part of the fiber's peripheral surface. Such composite fibers not only have latent crimping ability which, when induced, acts to fix the fiber bundles, but the presence of such a potentially adhesive component allows further fixation of the fiber bundles by the fiber bond that is a consequence of the activation.

Suitable components for the production of the composite fibers can be found in all groups of synthetic fiber-forming materials. Due to their commercial availability, ease of manufacture and excellent properties, the condensation polymers, e.g. polyamides and polyesters, and especially those that can be melt spun,

very well suited for use according to the present invention. Other composite fibers that can be used include e.g. those based on or containing polyester amides, polysulfonamides, polyesters, polyolefins, polyurethane or any combination of these polymers. The only significant limitation must be that the components of the composite fibers must be sufficiently resistant to resist fibrillation.

Examples of suitable composite fibers include those listed in the table below.

Such composite fibers retain their shape and their

identity as filaments during activation of the potentially adhesive component due to the fact that the other component of the heterofilament is relatively unaffected by the activation treatment.

There are a number of methods by which

the composite fibers can be produced. They can thus e.g. are produced according to the methods described in the British patent documents no 579 081, 580 764 and 580 941, which involve co-spinning in a melt spinning process, a plasticized melt spinning or wet or dry spinning of the polymer materials so that they form a uniform filament. Before or during the spinning operation, plasticizers, pigments, dyes, moth repellents, fire retardants, fillers, abrasives and/or light stabilizers can be added. Especially when the potentially adhesive component is activatable under the influence of heat, it may be desirable to add the spinning solution or otherwise add the potentially adhesive component to the composite fiber suitable substances for lowering the softening point of the component,

such as e.g. plasticizers, soft resins, etc. Among suitable plasticizers for this purpose are dibutyl tartrate, ethyl phthalate and an ethyl glycolate.

Examples of suitable soft resins are polyvinyl acetate, ester gum, coumarone resin and lower molecular weight alkyd resins. For the purposes of the invention, the components of the composite fiber can e.g. be arranged side by side in relation to each other, or a component can be completely enclosed by another component, i.e. in the form of a so-called shell and core connection, where the component that forms the shell is the potentially adhesive component. Or the heterofilament can be of a non-circular shape, e.g. trilobal with one or two of the arms formed by the potentially adhesive component. The relative proportions of the components that make up the composite fiber can be varied according to the type of textile fabric that is required, when one takes into account the physical properties that are desired for the fabric and the intended uses.

The composite fibers can be mixed with up to 90% of fibers that do not have latent frizz.

The fiber web can be produced by air deposition of the fibers, by netting, by carding the fibers, often followed by cross-laying of the carded webs, by paper-making techniques and in fact by any method where a web of loose connected fibers can be formed.

To a certain extent, the method used depends on the length of the fibers.

The base layer, which consists of one or more such fiber piles, will usually have a weight of more than approx. 13.5 g/m o and preferably not less than 33.8 g/m 2 , so the weight of the elementary fiber pile is adjusted in relation to the desired weight for the base layer and the number of such piles used for its production.

The weight of the fiber bundle front layer depends on the fiber bundle density and the greater the density that is desired, the heavier this layer must be and vice versa. Typically, the fiber bundle front layer will have a weight of between 13.5 - 169 g/m 2.

The needle felting operation is carried out on an ordinary needle felting chair which is well known to be used for such textile purposes. The penetration density, i.e. the extent of the needle penetration, can vary considerably, and as the fiber density is dependent on this parameter, variations in this will be reflected in the appearance of the non-woven fabric. During the practice of the invention, penetration densities are in the range of between approx. 8 stitches/cm 2 up to over 1000 - let's say 1700 stitches/cm 2 , found to be suitable, while around 31 stitches/era is the most common. The depth of the needle penetration depends on the thickness of the composite structure and it must be remembered here that it is essential that the fibers which are reoriented by needle punching protrude beyond the surface of the base layer in the form of floss or fiber bundles.

The treatment by means of which the fibers in one or both layers are crimped and the fiber bundles are fixed can include heating by means of various devices such as

water, oil, steam, air or another fluid which is relatively inert in relation to the particular fiber material used. Alternatively or in addition, the processing may consist of delaying

the needle felted product for a suitable chemical treatment. Mild acid or alkaline baths are examples of what can often be suitable chemical treatments.

Binding of the fibers in the base layer to each other

and to the vertically arranged fibers passing through this,

if it is desired to enhance the effect of the fiber crimp during fixation of the fiber bundles, this can be achieved in many ways and the particular method used is largely dependent on the fibers present in the structure.

Thus when the fibers that are present in the base layer

are simple one-component fibers, i.e. homofilaments, it is often appropriate to bond the fibers herein and in the fiber bundle front layer by applying a binder to the composite needle felted structure on the front layer side. The binder diffuses through the fiber structure and binds the fibers together, whereby the fiber bundles are fixed.

Many different binders can be used accordingly

to the invention. It can be an aqueous or non-aqueous solution, emulsion or dispersion of a binder or of a potentially adhesive material which, after curing, forms adhesive compounds. Examples of suitable binders include rubber (natural or synthetic), polyurethanes, polyvinyl resins such as polyvinyl acetate, polyvinyl alcohol and polyvinyl chloride, and polyamide resins.

The binder is conveniently applied in liquid form to the relevant surface of the composite needle felted structure by spraying, e.g. through ordinary spray nozzles or with the help of an application vase. Alternatively, the binder can be spread over the fiber bundle front layer surface using a foam.

The binder can also be in the form of a binder incorporated in the base layer, as the binder becomes potentially sticky* under conditions that do not affect the fibers therein. E.g. the binder can have a softening point below the softening point of the fibers present and can thus be made adhesive, i.e. activated by means of heat. In such cases, the treatment may conveniently consist of heating to a temperature above the softening point of the additional binder but below the melting point of the fibers. The heating can be carried out by passing the composite needle felted structure over a hot drum in such a way that only the surface of the structure which is on the opposite side of the fiber bundles is brought into contact with the drum. The binder may also be capable of being activated by means of suitable chemical agents, where the treatment may then suitably consist of adding a suitable chemical agent to the fiber bundle front layer in the composite structure.

The binder can be activated using heat or chemical means. The binders that can be activated with the help of heat or chemical agents are often in the form of powder, fiber fluff or staple fibres.

When the base layer and/or fiber bundle front layer contains composite fibers of the type consisting of at least two synthetic polymer components, it is often appropriate to have present in the composite fiber at least 1 component that can be made adhesive under conditions that allow the other component or components to be not sticky. The potentially adhesive component is arranged so that it forms at least part of the filament's periphery, because thereby the treatment to bind the fibers in the fiber pile base layer and thereby fix the fiber bundles will only consist of activating the potentially adhesive component. The activation can be carried out in the same treatment that is used to develop ripples in the heterofilaments or a subsequent treatment. •

Particularly suitable composite fibers for use in connection with the method according to this invention are those where the potentially adhesive component has a lower softening point than the other component or components and can thus be activated and the fiber bundles thereby anchored by means of a treatment that includes heating. As examples of such composite fibers

can be mentioned: polyhexamethylene-adipamide-polyepsiloncaprolactam

(nylon 66/6) filaments where polyepsiloncaprolactam is the component with the lowest melting point; polyhexamethylene adipamide-polyomega-aminoundecanoic acid (nylon 66/11) filaments where the polyomegaaminoundecanoic acid component has the lowest melting point, and polyhexamethylene adipamide/polyhexamethylene adipamide-polyepsiloncaprolactam copolymer filaments where the copolymer component has the lowest melting point.

The potentially adhesive component of the composite fiber may be such that it can be activated and the fiber bundles thereby fixed by treatment using suitable chemical agents, e.g. by treatment with a substantially non-aqueous formaldehyde solution. An example of such a heterofilament is one consisting of polyhexamethylene adipamide as one component and an 80/20 random copolymer of polyhexamethylene adipamide and polyepsiloncaprolactam as the other component. Here it is the copolymer component that can be activated by means of a warm ethylene glycol solution of formaldehyde which does not affect the polyhexamethylene adipamide component and allows it to remain essentially non-adhesive.

Introduction into the base layer and/or fiber bundle front layer of at least a certain proportion of composite fibers of the type

as mentioned above, allows the bundles to be fixed in an appropriate and efficient manner as a result of what is in reality an in situ development of a binding agent through the activation of a potentially adhesive component in the heterofilaments. The activation of the potentially adhesive component is usually carried out without degradation of the fibrous nature of the heterofilament, because the activated component is held in close association with the other component. This retention of fiber character and the absence of binder from the structure itself is believed to be of importance in terms of properties such as bundle formation and tenacity, properties that help determine the durability of the pole surface and also the colorability of the resulting pole fabric. in addition, the use of composite fibers will provide precise control of the amount of binder and uniform distribution through the fiber pile.

The non-woven pile fabrics according to the invention find special use as carpet materials, but they are diverse in terms of purposes of use, e.g. can they be used for furniture fabrics.

During their use as floor coverings, the new fabrics can advantageously be provided with a base material.

The invention will now be further described with reference to the following illustrative examples and the accompanying drawings, where

fig. 1 is a diagram which, in sequence, illustrates a simplified embodiment of a method for producing polar fabric according to the invention,

fig. 2 is a schematic cross-section of the layered construction according to fig. 1 before needle felting,

fig. 3 is a schematic cross-section of the composite needle felted structure according to fig. 1.

Fig. 4 is a schematic cross-section of the composite needle felted structure according to fig. 1 after the fibers in this have been crimped.

With reference to the other figures, there is in fig. 1 shows a supply roller 10 for fiber pile 11, which is unwound from the supply roller and is moved horizontally from left to right on the surface of an endless belt 12. The layer 13 which

is formed in this way must be used as a base layer during the formation of the non-woven fleece product. The reference number 14 denotes a supply roller for fiber pile 15 which is continuously laid down by means of a roller 16 in the form of a layer 17 on the base layer 13 and moved at the same speed and in the same direction as the latter. The composite structure shown in fig. 2 and which consists of the fiber pile 17 as a fiber bundle front layer on a base layer 13 is then taken to a needle felting chair, generally indicated by reference number 18 and which is of ordinary construction.

The needle felting chair 18 consists of a horizontal surface 19

and a needle table 20. The needle felting chair moves the needle into and out of the fiber pile and reorients some of the fibers in the pile to plane normal or substantially normal to its plane surface.

The vertically arranged fibers protrude beyond a flat surface

in and through the base layer in the form of fiber bundles.

The composite needle felted structure 21 which is formed on

this way is shown in fig. 3. It consists of 3 superimposed layers, a bundle front layer 17, the base layer 13 and a layer of fiber bundles 2 7 which give the resulting fabric its pole surface and which represent the projections of vertically arranged fibers 29

embedded in the base layer out past a flat surface 28 of the base layer. The base layer contains not only fibers 29, but also other fibers 30 arranged in a plane substantially normal to the plane of the vertically arranged fibers 29. The base layer serves in addition to its role as reinforcement of the non-woven fabric and support of the fiber bundle front layer 17 during the needle felting operation, also to shape and hold the fiber bundles which are needle felted into it.

The composite needle felted structure 21 is then subjected to a finishing treatment, e.g. immersion in boiling water,

to crimp the fibers. The devices that are used for this purpose are indicated by reference number 22 in fig. 1. The development of the ripples in the fiber bundles 27, as can be seen from fig. 4, results in a spreading of these with subsequent leveling or spreading of the bundles over the surface. During the execution of this, it gets a more rounded design. In reality, the individual curly bunches with a short vertical stem will 31

stand directly above the base layer 13 and end in a rounded cap 32 which has the general appearance of a mushroom.

The non-woven pile fabric 23, after the crimping treatment, is passed through a zone, indicated by reference number 24 in fig. 1, where funds have been arranged, e.g. an oven, to further fix the fiber bundles in the base layer. The pile fabric 25 that is thus formed is wound up on a frame 26.

EXAMPLE 1

A portion of 15 denier, 5 cm staple fibers formed from composite fibers consisting of polyhexamethylene adipamide as one component and polyhexamethylene adipamide/polyepsiloncaprolactam copolymer as the other (nylon 66//66/6), where the two components were arranged side by side in relation to each other, was carded using a normal textile operation. A fleece weighing approximately 135.2 g/m<2> was then formed from the carded layers by means of a cross-laying machine which laid the fleeces on top of each other with subsequent layers arranged at an angle of 90° in compared to the previous layer. The fleece, which consisted of loosely connected fibers, was dimensionally stabilized by passing through a common needle felting chair and was then fed into a color sheet (Solway Blue BN) in which the dispersing agent was boiling water.

As a result of the introduction into the dye bath became

the fibers in the felt not only dyed but also shrunk. This latter effect caused the composite fibers to assume a crimped, looped or folded form with considerable

locking and interweaving of adjacent fibers and a through-

ongoing contraction of the fleece to a smaller volume (approximately 60% shrinkage in area). The resulting dense fluff had a weight of about 301.2 g/m . This flor is hereafter referred to in this example as flor A.

Another flor (referred to in the following as

flor B) with a weight of approximately 67.6 g/m 2 was produced by carding and crosslaying a portion of 15 denier, 15 cm staple fibers formed from heterofilaments similar to those used in the production of flor A.

With flor B as the fiber bundle front layer and flor A as the base layer, which had previously been dried at a temperature well below 200°C, the composite structure was passed through a single needle bed needle felting chair with 25 gauge regular point needles. Needle felting in this manner oriented the fibers of flor B through flor A which acts as the base layer, so that the fibers of flor B protruded past the underside of flor A. The resulting nonwoven fabric had an appealing textile-like grip, good pliability or drapeability, and a satisfactory tensile strength. In order to

improve the tensile strength, which at this stage was only due to interlocking of fibers and entanglement caused by the crimp, the felted structure was heated in an air oven for a period of 3 - 4

my. at a temperature of 230 - 240°C. During this heating period, the composite fibers in flor B, the majority of which had been tufted through flor A, were crimped whereby they gave increased stability to the structure in both the thickness direction and in the plane of the fabric.

The development of the ripples led to a spreading of the fiber bundles during the formation of mushroom-shaped structures. The spread of the fiber bundles in this way was reflected in a denser pole surface with a correspondingly improved coverage of the base layer which was completely hidden and invisible, further the transformation of the bundles from essentially vertically arranged structures to more spread out and rounded mushroom-shaped structures led to the non- woven fleeces were given better performance properties. According to the givenness, the flexibility e.g. i.e. the ability of the pole surface to return to its original shape after deformation (e.g. by placing weights on it), was greatly improved.

As the needle felted product reached the ambient oven temperature at which point all fibers were substantially fully crimped, the component of the composite fibers with the lowest melting point, i.e. the polyhexamethylene adipamide/polyepsiloncaprolactam copolymer which melts at a temperature of about 220°C, became adhesive, developed its sticky properties and caused fibers in contact with each other to melt or stick together.

As a result of this fusing, the part of each of the tufted fibers present in the base layer, formed by the fibers of ply A, was bonded together with adjacent fibers of this ply, thereby forming a tufted fabric with sufficient tensile strength, good wear resistance and usable flexibility or draping ability. The tufted fabric was then placed in a dye bath to dye the fibers in flor B (tufted fibres) and then dried.

A so-called differential color effect could be achieved by first dyeing the fibers in flor A with a dark color and then the bundles in flor B with a lighter color in a different dye bath.

The tufted fabric was perfectly usable as a floor rug or as furniture fabric. Structurally, it consists of a dense mat of interwoven and interlocked fibers.

During the use of the tufted fabric as a floor carpet

it is often advantageous when it comes to preventing slippage and obtaining good dimensional stability to use a strip substrate to which the back of the fabric is attached by means of the application of a suitable binder.

EXAMPLE 2

A portion of 12 denier, 5 cm staple fibers formed from heterofilaments similar to those used in the manufacture of the fleeces of Example 1 was carded and cross-laid to form a fleece (hereafter referred to as fleece c) having a weight of approximately 270,'4 g/m Another flor (hereafter referred to as flor D) identical to flor B described above in connection with example 1, was produced, by means of a carding and crosslaying technique and then laid as the fiber bundle front layer on flor C as the base layer. The fibers in the face layer were then needle felted through the fibers in flor C by passing the combined structure through a needle felting chair with 32 gauge regular pointed needles. The tufted structure was then heated in an air oven for a period of 3-4 min. at a temperature of 230 - 240°C. During this heat treatment, the heterofilament fibers were crossed, and the needle felted product contracted to a smaller area (approximately 45% shrinkage in area content) and finally, as the fibers reached the ambient oven temperature, the component of the heterofilament fibers that had the lowest melting point ( i.e. the polyhexamethylene adipamide/polyepsiloncaprolactam copolymer which melts at a temperature of about 220°C) its adhesive or bonding properties and caused fibers in contact with each other to stick or fuse together. This fusing of adjacent fibers increased the tensile strength of the nonwoven fabric, which previously was mainly caused by fiber entanglement produced due to crimping.

The fabric was dyed by placing it in a dye bath and then dried.

The tufted fabric produced a very useful carpet material when it was attached to a suitable base material such as e.g. jute strip with or without foam rubber or polyurethane foam.

Instead of an entone color effect, a differential color effect can be achieved in the tufted fabric by producing flor C from spin-dyed heterofilament staple fibers and dyeing only the tufted fibers in flor D, or by producing flor C and D

of different heterofilaments, as the heterofilaments in flor C have different color properties compared to the heterofilaments in flor D.

EXAMPLE 3

The procedure of Example 1 was repeated, except that flor A consisted of 12 denier, 3.75 cm supercrisp polyhexamethylene adipamide fibers and had a weight of about 202.8 g/m 2 .

The tufted fabric produced by crimping and melting (by heat) fibers in the needle felted structure had a softer and better developed textile-like grip than the fabric according to example 1 and the knot anchoring was excellent and gave the fabric good wear resistance.

EXAMPLE 4

The procedure according to example 1 was repeated

except that flor A consisted of a mixture of equal parts by weight 20 denier, 5 cm heterofilament staple fibers and 6 denier, 3.75 cm polyhexamethylene adipamide staple fibers.

The tufted fabric again had a softer grip than the fabric according to example 1 and its tensile strength, which is due to the combined effect of fiber crimping and fiber fusion, was sufficient.

EXAMPLE 5

In this example, the procedure of Example 1 was followed except that flo B, i.e. the flo forming the waterfall bundles in the resulting fabric, consisted of a mixture of equal parts by weight 15 denier 5 cm heterofilament staple fibers and 12 denier, 3.75 cm polyhexamethylene adipamide staple fibers.

EXAMPLE 6

The procedure according to example 1 was repeated except that a loosely woven net strip fabric was placed between the piles A and B immediately before the needle felting operation.

Introducing the net strip in this way produced a tufted fabric where the anchoring of the bundles in the base layer, formed by the fibers in flor B, was much improved compared to the anchoring of the bundles in the product according to example 1. Furthermore, the tufted fabric could be used as a floor carpet without some underlay material of straw, which was often necessary when the material according to example 1 was used for the same purpose.

EXAMPLE 7

In this example, the procedure of Example 1 was followed except that both a loosely woven mesh fabric and a foam rubber web were placed between the piles A and B immediately prior to the needle felting operation.

The effect of the foam rubber was to improve the flexibility and compliance of the resulting tufted fabric.

EXAMPLE 8

A proportion of 12 denier, 5 cm staple fibers formed from a composite fiber containing equal parts by weight of polyhexamethylene adipamide as one component and an 80/200 random copolymer of polyhexamethylene adipamide/polyepsiloncaprolactam as the other was used. The two components were arranged side by side in relation to each other and were air laid using a Proctor and Schwartz "duo-form" air laying machine so that a fiber web with a weight of approximately 67.6 g/m 2 was produced.

A second fiber web weighing 304.2 g/m 2 was also air laid using the same air laying machine from a mixture consisting of equal parts by weight of the composite fiber present in the first web and a 15 denier, 5 cm black dyed three-armed (trilobal) polyhexamethylene adipamide. This fleece was then dimensionally stabilized by a weak needle punch (approx. 35 stitches or penetrations per cm 2 ) in a single pass through a normal needle felting chair. The needle felting was found to facilitate further processing, to stabilize the fiber bundle front layer during the needle felting operation and also to improve the wear resistance of the finished fabric.

The first ply was then laid as the fiber bundle front layer on the second, which formed the base layer. The composite structure was passed through a single bed needle felting chair of the type manufactured by William Bywater Ltd., Leeds, and fitted with 25 gauge regular point needles. The composite structure was passed twice through the needle felting chair. During the first pass, the penetration density was approx. 12 penetrations per cm 2, and during the second it was 24 penetrations per cm 2. During both penetrations, the needle depth was adjusted so that the needles penetrated at a distance of approx. 15 mm (5/8")

out past the undersurface of the base layer and the first few needle hooks passed completely through this.

The needle felted structure, which was approx. lm wide (43") was passed through an Efco belt furnace which had a temperature of 245°C

and with a completion speed of approx. 3 m/min. Due to the heat treatment, the composite fibers in the structure were crimped and bound together into a stable structure approximately 96 cm wide (40").

The product was dyed to a two-tone effect due to the presence of black fibers in the base layer. After dyeing, abrasion tests were carried out on a sample of the needle felted structure both before and after the development of curling and bonding between the fibers.

The measurements were carried out on a Taber wear tester during a

load of 100 g and H 10 wear wheel with 500 revolutions of the wheel.

It was found that the product before the heat treatment

lost 0.171 g of fibers, which is well comparable to ordinary carpet materials, while the product after the heat treatment lost 0.120 g of fibers, which was excellent, and its appearance was unchanged.

EXAMPLE 9

A portion of 6 denier, 3.75 cm staple fibers formed from a composite fiber containing equal parts by weight of polyethylene and polypropylene with the two components arranged side by side relative to each other was air laid using a Proctor and Schwartz "duo-form" air laying machine so that a flor with a weight of approximately 84.5 g/m 2 was presented.

Another fiber web weighing 270.4 g/m 2 was also air-laid using the same air-laying machine from a mixture consisting of equal parts by weight of the composite fibers in the first web 5 denier, 5 cm black-dyed, three-armed (trilobal) shaped polyhexamethylene adipamide fibers. This fleece was then dimensionally stabilized by light needle punching with 35 penetrations per cm when passing through a normal needle felting chair. The needle punching was found to facilitate further fabrication, to stabilize the fiber bundle front layer during the needle punching operation, and also to improve the wear resistance of the final fabric.

The first ply was then laid as the fiber bundle front layer on the second, which formed the base layer. The composite structure was run through a single needle bed needle chair of the type manufactured by WilliamBywater Ltd., Leeds, and fitted with 25 gauge regular barbed needles. The composite structure was passed through the needle chair twice, during the first pass the penetration density was approx. 12 penetrations per cm 2 and under the other it was approx. 24 penetrations per cm 2.

During both passes, the needle depth was adjusted as follows

that the penetration was a distance of approx. 15 mm (5/8") out past the outer surface of the base course, and the first few notches passed fully through this.

The needle felted structure was passed through an Efco belt furnace operating at a temperature of 165°C, and with a passing speed of approximately 3 m/min. Due to the heat treatment, the composite fibers in the structure were crimped and bound together into a stable structure with a pole surface composed of mushroom-shaped fiber bundles. The fabric was very suitable as a floor carpet, for which purpose it could be advantageously equipped with a straw underlay.

Claims (2)

1. Nonwoven fabric comprising a nonwoven fiber base layer (13) and a nonwoven fiber bundle front layer (17) with the fibers (29) from the front layer oriented through the base layer and protruding past its planar surface in the form of fiber bundles ( 27), with at least a proportion of the fibers in at least one of the layers being composite fibers containing at least two fiber-forming synthetic, polymeric components arranged in separate zones across each fiber's cross section, each component being continuous in the longitudinal direction of each fiber, characterized in that at least one of , but not all, the components are potentially adhesive and arranged so that it forms at least a portion of the peripheral surface of each fiber, and the fiber bundles are fixed in the structure by means of said potentially adhesive component's adhesive properties. 2. Non-woven fabric as stated in claim 1, characterized in that at least a proportion of the composite fibers in at least one of the layers is crimped.