IE44985B1 - Apparatus for treating woven fabrics - Google Patents

Description

This invention relates to apparatus for treating woven fabrics and is divided from our co-pending Patent Application No. 44 98Φ. One particular example of an application of the apparatus of this invention is the treatment of a woven fabric which is- intended for use as a carpet backing and which is formed from flat warp and weft tapes of synthetic resinous material, for example polypropylene.

When a woven fabric is said to be formed from warp and weft tapes this Is to be understood as meaning that the tapes have a cross-section in which the maximum dimension of width is substantially greater than the greatest thickness. Commonly the warp and weft tapes are obtained by individual extrusion or by slitting an extruded film of the synthetic resinous material. When the expression warp and weft tapes is used it is not intended to convey any particular state of either in respect of twisting and/or folding. When a woven fabric is said to be formed from flat warp and weft tapes this is intended to convey that the tapes are substantially twistless in the woven fabric and present a flat appearance. However, in a woven . fabric which is said to be formed from flat warp and weft tapes, there is Usually an incidence of twist or folding present, particularly in the case of the weft.

In the Specification of our co-pending Patent Application No. 44984 there is described and claimed a woven fabric having warp and weft of synthetic resinous material, both the warp and weft having been fibrillated in situ in the woven fabric such that the surface -244985 of'each warp and weft has a decreased reflective power as compared with untreated warp and weft, and the surface of the woven fabric being substantially free of surface hairiness.

During fibrillation the synthetic resinous elements which constitute the warp and weft of the woven fabric are caused to accept a multiplicity of longitudinal splits, such that each warp and weft is changed from an element having a continuous surface into a member which comprises fibrils which in general are joined together in the form of a random network. Any cross-section through a fibrillated warp or weft is also a cross-section through a multiplicity of fibrils. The fibrillating process causes the appearance of the surfaces of the warp and weft components of the woven fabric to be changed from a continuous and shiny surface to a matt appearance. Consequently, the woven fabric which has its warp and weft broken down into a multiplicity of fibrils by fibrillation in situ in the woven fabric has a markedly different reflective property in its surface as compared with the woven fabric before the treatment to produce the fibrils. The woven fabric after treatment has a relatively matt surface in contrast to the generally reflective nature of the surface before the treatment, Advantageously, the warp and weft of a woven fabric in accordance with our id co-pending Patent Application No, 44984 are fibri1 luted by repealed needling thereof. -3I The repeated needling of the woven fabric which effects fibrillation of the warp and weft is an operation in which the woven fabric is subjected to a very large number of needle penetrations. In order to effect a fibrillation which causes a significant decrease in the reflective power of the surface of the woven fabric, it is believed that each square centimetre of the woven fabric should be subjected to at least 800 needle penetrations. Preferably each square centimetre of the woven fabric is subjected to at least 1,800 needle penetrations, and, in the specific description which will follow, each square centimetre of the woven fabric composed of warp and weft elements of synthetic resinous material will be subjected to approximately 3,000 needle penetrations.

The present invention is concerned with the provision of apparatus for subjecting a woven fabric to the large number of needle penetrations per square centimetre required to cause a significant decrease in the reflective power of the surface of the woven fabric.

In accordance with the present invention there is provided apparatus for treating a woven fabric which comprises a needle board, a multiplicity of smooth-surfacedneedles of rounded cross-section mounted on the needle board with the tips of the needles all on substantially the same plane and arranged at a density of at least 75 needles per square centimetre over at least a part of the surface of the needle board, means for reciprocating the needle board such that the needles are moved axially, and a support -44498s capable of maintaining a woven fabric in a substantially planar configuration during reciprocation of the needle board such that the needles penetrate the warp and weft_of the woven fabric', the support accommodating, without damage to the needles1, the tips of the needles which penetrate the woven fabric.

It will be noted that, compared with conventional needle loom practice where densities up to about two per square centimetre are used, a needle density of a much , ID higher order is used in apparatus in accordance with the j present invention. ι I Advantageously, apparatus in accordance with the ι present invention has needles mounted in a needle density j over at least a part of the needle board of the order of { I 100 to 150 needles per square centimetre. In the specific j embodiment of the present invention which will be described the needles are mounted on at least a part of the needle board in a density of about 120 needles per square centimetre.

Preferably, the apparatus according to the present invention which is used for fibrillating the warp and weft elements in a woven fabric has needles of circular crosssection. The needles used in the needling operation in accordance with the present invention are to be contrasted with the needles used in the conventional needle loom which are of triangular cross-section.

Although in the preferred embodiment of the present invention the apparatus includes such needles of circular -5££©8S cross-section, it is envisaged that apparatus in accordance with the present invention may include needles of other cross-section, provided that these are smooth or rounded cross-section, i.e, provided that the peripheries of the 'needles-do not include discontinuities in direction such as are present, for example, in a needle of triangular cross-section.

By the use of needles of smooth or rounded crosssection any substantial lateral cutting of the warp and weft of the woven fabric is avoided and a matt surface is produced which is relatively free of surface hairiness.

The degree and form of the increase in effective width of warp and weft elements as a result of fibrillation by needling in the manner described are influenced by the initial construction of the woven fabric.

In the embodiments of the apparatus according to the present invention which will be described herein the support comprises a base having thereon a covering of chromed leather. However, a flocked fabric may also be used as the covering to the base.

Advantageously, the apparatus is so arranged and constructed that the needle board is vertically reciprocated sufficient times for each square centimetre of the woven fabric to be subjected to about 3,000 needle penetrations.

The present invention will be better understood from the following detailed description which is given, by way of example, with reference to the accompanying diagrammatic drawings, in which:-64 4985 Figure 1 is a side view of apparatus for treating a woven fabric of flat warp and weft tapes of polypropylene, Figure 2 ip an enlarged cross-sectional view of a part of the apparatus of Figure 1 taken along the line II-II of Figure 1, Figure '3 is a greatly enlarged perspective view of a needle used in the apparatus of Figure 1, Figure 4 ip a greatly enlarged plan view of a woven fabric comprising polypropylene tapes before treatment in accordance with the present invention, Figure 5 is a similar view of the same woven fabric following treatment using the apparatus of Figures 1 to 3, and -744985 steps of alternative processes of making woven fabrics in accordance with the present invention.

In the drawings the same or similar parts are designated by like reference numerals.

Referring to the drawings, there is shown in Figure 1 a woven fabric 1 which is formed from flat warp and weft tapes both composed of a synthetic resinous material. Conveniently both the warp and weft tapes are polypropylene tapes of rectangular cross-section, the weft tapes, for example, having a width of the order of two and a half millimetres while the warp tapes have a width of the order of one and a quarter millimetres. The woven fabric 1 is advanced in the direction of an arrow 2 towards a’fibrillating apparatus 3» « During its advance in the direction of the arrow 2 the woven fabric 1 (which may have a suitable lubricant applied to it) is passed through the fibrillating apparatus 3 which may be generically described ds a needling machine. The fibrillating apparatus 3 is howfevei*, different from a conventional needle loom in that it has a special needle board L and also a special support which supportό th4 woven fabric 1 during operation of the needle board- +.

The needle board * carries needles 5 of circular crosssection, which are fine heedles arranged on the needle board in dense groups 5a, 5k, etc. (see Figure 1). Each group of the needles 5 contains four strips of needles 5 extending laterally across the width of the fibrillating apparatus 3, es shovm in Figure 2, the needles in each strip being a row containing approximately 16 needles to each centimetre length of the strip - 8449 The overall width of each group 5a, 5k, 5c etc. of needles is approximately 5 millimetres, with the result that each area of the needle board h which carries a group of needleB 5a, 5k, 5e etc. has the needles mounted in a density of the-orderof 120 per square centimetre. There is a spacing of the order of 10 millimetres between the separate groups 5a, 5b, 5c etc. of needles.

As the woven fabric 1 is passed through the fibrillating apparatus 3 it is supported by a surface covering 6 on a solid base or bed 7· The surface covering 6 used on the bed 7 is advantageously chromed leather. When leather is used, the needle board h is preferably reciprocated to cause the needles 5 to perforate the surface of the leather covering on the bed.7 in the absence of any woven fabric 1, thereby forming in the surface of the leather minute holes for receiving the tips of the needles 5 while the remainder of the surface of the leather provides a close support for the woven fabric 1 around the areas where the needles 5 impact the woven fabric 1. 2° As the woven fabric 1 advances in a step by step manner through the fibrillating apparatus 3, the needle board k is reciprocated at a sufficient rate to impart 3,000 needle I penetrations per square centimetre .

In Figure 3 there is illustrated one of the needles 5 which are mounted densely on areas of the needle board k as illustrated in Figures 1 and 2. The needle 5 has a circular cross-section.

In operation of the fibrillating apparatus 3, at least the tips of the needles 5 are required to penetrate through the woven fabric 1.

Variations in the finish produced by treatment of a woven fabric by the method of the present invention may be achieved by adjusting the degree of penetration of the needle tips and the density of needling. The density of needling is affected by the density with which the needles are mounted in the apparatus, and by the rate at which the woven fabric is advanced through t'he apparatus in conjunction with the speed at which the needles are reciprocated by the apparatus.

The effect of repeated penetration of the warp and weft tapes making up the woven fabric 1 by the needles 5 is to make a large number of splits in each warp and weft tape so that, at any cross-section through a warp or a weft tape , it is comprised of a multiplicity of fibrils. The consequence is that the shiny surfaces which were present in the warp and weft tapes as the woven fabric 1 approached the fibrillating apparatus 3 are replaced by a broken-up surface, consisting of a multiplicity of fibrils so that the warp and weft components of the woven fabric are composed of fibrils. The effect of the breaking-up of the surfaces of the warp and Weft tapes by the fibrillating apparatus 3 is that the degree of reflectivity in the woven fabric 1 emerging from the fibrillating apparatus 3 is substantially reduced as compared with its reflectivity before treatment in the fibrillating apparatus 3· The woven fabric 1 which has been treated in the fibrillating apparatus 3 in accordance with the present Invention has a relatively matt surface as a result of the woven fabric being composed of warp and weft eacn of which has -104 4383 been obtained by fibrillating a warp or weft tape in situ in the woven fabric. Each warp or weft therefore comprises a multiplicity of fibrils, which constitute a flat bundle , giving a visual impression that the fibrils lie substantially in the same plane.

The fibrillation of the warp and weft tapes of the woven fabric 1 by the action of the fibrillating apparatus 3 ? has the effect of causing the warp and weft to tend to spread so that, if such spreading is possible, the fibrils which comprise each of the warp and weft after the fibrillating treatment have a greater combined width than the respective tape prior to the fibrillation treatment. This spreading of the,warp and weft elements of the woven fabric 1 in the fibrillation treatment is believed to be facilitated by causing more than the tips of the needles 5 to penetrate the tapes of the woven fabric.

Figures b and, 5 of the accompanying drawings illustrate the surface appearance of the woven fabric 1 before and after the treatment in a fibrillating apparatus 3.

Referring to Figure b· there are shown warp tapes 11 and 20 weft tapes 12 each formed from polypropylene. The surfaces of the tapes 11 and 12 which are exposed in the woven fabric 1 are smooth and shiny as a result of the tapes being derived from an extruded film of polypropylene. It will also be observed in Figure k that there tend to be spaces between the warp tapes 11 and the weft tapes 12.

Referring now to Figure 5, the woven fabric after the treatment by the fibrillating apparatus 3 has individual warp and weft 13 and 14 comprised of a multiplicity of fibrils which -11give the woven fabric of Figure 5 the appearance of a basket-weave. The breaking down of each tape 11 and 12 by splitting into a multiplicity of fibrils causes the surface of the woven fabric of Figure 5 to be relatively matt as compared with the surface of the woven fabric of Figure Also the. splitting of the individual warp tapes 11 and weft tapes 12 each into a multiplicity of fibrils causes both to spread with the result that any gaps which previously existed between edges of the warp and weft components of the woven fabric 1 are substantially reduced.

In general the breaking-down of the warp tapes 11 and weft tapes 12 into the multiplicity of fibrils which comprise the warp 13 and weft 1½ will cause the resultant warp and weft components to have a greater width than the original tapes as 1? described above at least where the warp and weft constitute the exposed surface of the woven fabric 1, e.g. where a warp is supported by a weft. However, the ability of the warp and weft to spread may be restricted in fabrics which have a close initial construction.

The treatment in accordance with the present invention to break down each warp and weft into a multiplicity of fibrils may be effected with a lesser number of needle penetrations than 3,000 per square centimetre.

There will now be given examples of Woven fabrics which are treated by fibrillating warp and weft tapes in situ in the woven fabric.

EXAMPLE 1 A woven fabric was formed from warp and weft tapes of -1244985» polypropylene which were both of generally rectangular crosssection. The warp tapes, drawn at a draw ratio of 6s1, were approximately one and a quarter millimetres in width, the weft tapes, drawn at a draw ratio of 7s1, had a width of approximately two and a half millimetres, and both warp and weft tapes had a thickness of the order of 50 microns, the warp tapes being approximately 500 denier and the weft tapes being approximately 1,000 denier. In the woven fabric formed from these warp and weft tapes there were 9*+ warp ends per 10 centimetres and 51 weft ends per 10 centimetres.

Each square centimetre of this woven fabric was subjected to about 3(000 needle penetrations using the fibrillating apparatus 3 described above with reference to Figures 1 to 3 of ‘ ' I the drawings. The resultant product is a woven fabric having , j warp and weft each comprised by a flat bundle of fibrils, the . ! individual fibrils being generally rectangular in cross-section.

The warp components are comprised of fibrils of bO denier average with a range from 13 to 70 denier, while the weft ! components are comprised of fibrils of 27 denier average with a range from 8 to 50 denier. ' EXAMPLE 2 The fibrillated woven fabric which is the product of i Example 1 was passed through the fibrillating apparatus 3 ia similar manner on two further occasions. The resulting woven fabric, which had been subjected to about 10,000 needle penetrations per square centimetre, was a markedly softer cloth than the product of Example 1.

Examination of the woven fabric which had been subjected 1 to about 10,000 needle penetrations per square centimetre showed I -13that a change in the shape of the fibrils in this cloth had occurred as compared with the product of Example 1. The product of this present example was a woven fabric composed of fibrils having a lower average denier and many of the fibrils had portions which were no longer rectangular in cross-section due to corners having been removed.

The fibrils of the warp components of the woven fabric resulting from 9,000 needle penetrations per square centimetre were on average of 18 denier and ranged from 6 to 35 denier.

The fibrils of the weft components were on average of 11 denier and ranged between 7 denier and 18 denier.

EXAMPLE 3 Subjection of the produot of Example 2 to two further passes through the fibrillating apparatus 3 so that each square 1? centimetre of the woven fabric was subjected to approximately 15,000 needle penetrations produced a further softening in the resulting product.

EXAMPLE k Polypropylene tapes of approximately 1,000 denier were used as both warp and weft in the weaving of a woven fabric having 39 warp ends per 10 centimetres and S>1 weft ends per 10 centimetres This woven fabric was then fibrillated using the fibrillating apparatus 3 described above in order to subject each square centimetre of the woven fabric to about 10,000 needle penetrations.

The products of Examples 2 and 3 are woven fabrics based on synthetic resinous material (polypropylene) which have been obtained by a process which is substantially cheaper than the -lk14 9 8 5 known conventional methods of producing a cloth of similar handle and properties from synthetic fibres. The product of Example k which is a woven fabric obtained by weaving tapes of 1,000 denier polypropylene , with 39 warp ends per 10 centimetres and 51 weft ends per 10 centimetres followed by the fibrillating treatment of the present invention is a cheaper manufacturing process than that of weaving from synthetic fibres a fabric having, for instance, some 200 or 250 warp and weft ends per 10 centimetres.

The woven fabric of Example 1 above and which has the form illustrated in Figure 5 possesses a substantial advantage with regard to the adhesion to it of material such as a latex.

It is known to attach to a woven fabric such as that illustrated in Figure U, when intended for use as a conventional carpet backing material, a coating or layer of latex in order to give the woven fabric a resistance to distortion, that is to say a resistance to deformation of the woven fabric from an overall rectangular shape towards a parallelogram or diamond shape. However, polypropylene is an hydrophobic material, and the surfaces of the polypropylene tapes which comprise the warp tapes 11 and the weft tapes 12 do not readily adhere to an adhesive material such as latex. Accordingly, a coating of latex is secured to the woven fabric of Figure 4 by a mechanical interlocking or keying of the latex into the gaps between the warp and weft tapes of polypropylene, and in order to obtain this mechanical keying of the latex to the fabric a relatively thick coating of latex is necessary.

However, the product of Example 1 and Figure 5 has a much greater facility for adhering a coating, for example a -15latex, to the woven fabrio. The fibrils in the warp and weft IJ and 14 present many more exposed edges for latex adhesion, and in consequence a layer or coating of latex may be applied to the woven fabric of Figure 5, with a much lesser thickness than is necessary in order to secure a latex covering to the woven fabric of Figure It has also been found that a more uniform spreading of the latex can be achieved.

This has a significant advantage in economy in the quantity of latex used. There is a further advantage in that the thinner layer of latex which may be used to prevent mechanical distortion of the woven fabric of Figure 5 may be pierced relatively easily by a tufting needle when the woven fabric is used as a carpet backing material. This is in contrast to the difficulty which the tufting needle has in piercing the woven fgbri;e of Figure wiiich requires the substantially thicker coating of latex in order to obtain adherence between the latex and the fabric, with the result that * * ! the tufting needle is liable to punch holes in the fabric, and thereby damage the backing material.

A further and very important advantage which is provided hy the woven fabric of Figure 5 is the ability to impart colour to a woven fabric based on polypropylene. Hitherto it has been one of the major disadvantages of woven fabrics based on polypropylene , when used as carpet backings, that they have 2? a poor dye characteristic and in consequence the backing material is particularly likely to show up through dyed yarns which constitute the pile of the carpet. The present Applicants have found that the woven fabric treated in the manner described in accordance with the present invention, and -36 4 4 9 8 5 as illustrated in Figure 5, may be readily rendered dyeable by appropriate dyestuffs. This is achieved by applying to the woven fabric of Figure 5 a latex which has the ability to be dyed. Latex having the ability to be dyed, for instance by an acid dyestuff (hereinafter referred to as acid-dyeable latex) is obtainable, for example, from Rohm & Haas. The latex is applied to the woven fabric of Figure 5 by any suitable method, for example, by spraying or by using a doctor blade or by passage of the woven fabric in contact with the upper surface of a roller the lower surface of which is passing through a bath of the dyeable latex. An applicator 1? for applying the dyeable latex is shown diagrammatically in Figure 6, which is a flow diagram illustrating this aspect of the present invention.

The Applicants have made comparative tests in which similar quantities of acid-dyeable latex have been applied to the woven fabrics of Figures 't and 5. These tests have shown that, when the two woven fabrics, each carrying similar layers of acid-dyeable latex, are treated in a bath of acid dyest.ff, the woven fabric of Figure *+ shows little overall coloration, whereas a significant and uniform depth of colour appears in the latex-coated woven fabric of Figure 5· Good coloration of the woven fabric of Figure J? has been obtained with an addition of only about 12·^ by weight of the acid-dyeable latex, 2? Accordingly the woven fabric of Figure 5 with the acid-dyeable latex is suitable for use as a primary backing for tufted V carpets of which the pile is a material such as polyamide which is subsequently dyed using an acid dyestuff.

I Examination of the woven fabric of Figure 4- after -178® treatment with an aoid dyestuff shows that such coloration as is present occurs principally at the edges of the polypropylene tapes which comprise the warp tapes 11 and the weft tapes 12.

» It xb believed that the very marked improvement in coloration 5 which occurs as a result of the acid dye treatment of the woven fabric of Figuire 5 after coating with acidL-dyeable latex is a consequence of the presence of,a multitude of edge surfaces in the polypropylene material which makes up the warp and weft 13 and lk- as a reshit of the fibrillation of the warp and weft tapes during the passage of the woven fabric 1 through the fibrillating apparatus 3.

Accordingly, the woven fabric of Figure 5, in which the warp and weft 13 and 1*+ are broken down so that each warp or weft is essentially a flat bundle of fibrils, is a backing material for use in the manufacture of tufted carpets which may be employed successfully to reduce the incidence of grinning.

However, the woven fabric of Figure 5 which, presents a large number of edge surfaces to the fibrils in the warp and weft 13 and 14 is also found to be capable of coloration by dyeing if the woven· fabric is made from a dyeable synthetic resinous material, suoh-ae a polyester, a polyamide, a CV polyacrylonitrile, a polyvinyl alcohol,^a polyvinyl chloride, a cellulose acctauc or a viscose-material. The woven fabric which is the product Of Figure 5 is also dyeable when made of a 2? generally ηοη-dyeable synthetic resinous material if a dyeable component is incorporated in the generally ηοη-dyeable synthetic resinous material, such· as polypropylene, before this material is extruded and formed into tapes, woven into a fabric and then fibrillated. -1844985 Figure 7 illustrates a flow diagram for carrying out this process. It has been found that; when a disperse dyeing agent is included in the polypropylene from which the woven fabric is made, the woven fabric which ie the product of Figure 5 is dyeable to a good coloration - markedly better than the coloration obtained when a woven fabric made from the same polypropylene and disperse dyeing agent is dyed when in the form of the product of Figure k. The product of Figure k takes up some colour but not a great deal; the coloration of the product of Figure k has not been adequate for many uses of the woven fabric, including it:, use as a primary carpet backing.

Another method of applyin coloration to the woven fabric 1, the warp and weft components of which are fibrillated using the fibrillating apparatus 3, is by adding pigment to the synthetic resinous material (for example polypropylene) when this material is extrided. Such a pigmented woven fabric when fibrillated to produce the product of Figure 5 has particular use as a furnishing fabric or a wall fabric as a result of the ?0 matt finish which is nuch pref ι-able to the shiny finish.

As already indicated a woven fabrio 1 in accordance with the present invention and as illustrated in Figure 5 has substantial advantage: when used as a primary backing for tufted fabric. One of the most significant advantages is a substantial improvement in the overcoming of the defect known as needle deflection, which will be discussed further in relation to the products of Figures k and 5.

In the woven fabric of Figure k there tend to be spaces -194498° between the warp tap^s 11 and the weft tapes 12 so that there are four possibilities facing the tufting needle which strikes the woven fabric of Figure b. The tufting needle may Btrike a warp tape 11 in a position where it is unsupported by a weft tape 12, or it may strike a weft tape 12 in a position where the weft tape is unsupported by a warp tape 11, or it may strike the woven fabric at a position where the Warp and weft tapes 11 and 12 are supporting one another, or it may strike the woven fabric at a position where there is a gap between the edges of a warp tape 11 and a weft tape 12. In consequence of this considerable variation in the possibility facing the tufting needle , the tufting yarn which is secured to the woven fabric of Figure b in a tufting operation will have an uneven pile surface. 1? In the woven fabric of Figure 5 the warp and weft have been broken down into a multiplicity of fibrils and are less liable to needle deflection since the needle has a mucn greater chance of striking into a gap between fibrils. In consequence the woven fabric of Figure 5 presents less variety to the tufting needle than the woven fabric of Figure b and gives a more level pile surface to the final tufted carpet than that obtained by the tufted carpet produced from the conventional woven fabric of Figure b.

Because of the substantial decrease in the reflectivity . fhe surfaces of the warp and weft components which make up the woven fabric as a result of the treatment in accordance with the present invention, the woven fabric of Figure 5 is a more aoqeptable form of backing material for tufted carpets.

When the woven fabric of Figure 5 is tufted in order to -2 044983 produce a tufted carpet, it provides a more regular and consistent spacing of the tuft lines than is obtained by tufting the woven fabric of Figure k. This is because the surface of thp woven fabric of Figure 5 is a relatively good acceptor of the tufting needle in the sense that, wherever the tufting needle strikes the surface of the woven fabric of Figure 5, it will be able to penetrate between adjacent fibrils without causing any significant needle deflection. The tufts of yarn will thus be located at substantially the places where the tufting needles strike the surfaces of the woven fabric.

By contrast, the woven fabric of Figure k is not a good acceptor of ths tufting needle because the tufting needle must itself break through the surface of a warp tape 11 or a weft tape 12, and in some cases (particularly near the edges 1? of the warp and weft tapes) the tufting needle will fail to do this, but will deflect the warp or weft tapes to one side so that there will be an uneven spacing between that particular tuft of yarn and the adjacent tuft.

When a woven fabric which is intended for use as a carpet backing is fibrillated in accordance with the present invention the fibrillating treatment may be applied to the main central part -of the woven fabric but strips down the opposite edge portions of the woven fabric may be left untreated. The purpose of leaving edge portions of the woven fabric untreated is to retain in those edge portions good properties for enabling the woven fabric to be mechanically pinned during later treatment, the untreated I' portions being eventually trimmed from the woven fabric before the final carpet product is rolled. -21The fibrillation of the tapes in a;woven fabric of , . ί synthetic resinous material such as*polypropylehe using the fibrillating apparatus 3 as hereinbefore described, is not to be confused with the known process of tip-needling such a woven fabric. In a tip-needling process the woven fabric is passed through a needle loom similar to that used to needle an overlay of fibres to the woven fabric before tufting, as described earlier, but without introducing any fibres. Only the tips of the needles are caused to pierce the tapes in the woven fabric, the barbs on the needles being kept clear of the surfaces of the tapes. The purpose of tip-needling was to try to break-up the tapes in order to allow for more precise acceptance of the tufting needle and thus reduce the incidence of needle deflection, but in practice the use of tip-needling has increased the expense in producing the woven carpet backing without even being entirely successful in eliminating needle deflection. Furthermore the surfaces of the carpet backings after’treatment in a tip-needling process have retained their sheen and it has proved difficult to distinguish a tip-needled backing from one which has not been subjected to this treatment.

It is thought that there are two main reasons why the known tip-needling process has not produced the advantageous results provided in accordance with the present invention. Firstly, the tip-needling has been carried out with needles’ which have a triangular section. Secondly, the density of the perforations effected in a tip-needling process has been of an order of only 50 to 100 (usually about 80) penetrations per square centimetre which is a quite different order from that employed in the process of the present invention -22' 4 9 8 5 which, as previously stated, is at least '800 per square centimetre and preferably at least 1,800 per square centimetre.

Another significant difference between the fibrillating apparatus as described in the present Specification and the known needle loom is the nature of the support for the fabric while it is being treated by the needles of the fibrillating apparatus. In accordance with the present invention the base support, e.g. chromed leather, provides a close support against the back surface of the woven fabric, so that the fabric is effectively supported, but at the same time the support material is able to accommodate the tips of the needles without damage to the needles of the fibrillating apparatus.

The support which is provided in a conventional needle loom consists of a metal plate which has provided a hole or slot to I5 accept each of the needles. The complexity of providing such a metal plate in a fibrillating apparatus according to the present invention is enormous and thought to be impractical.

In order to facilitate the penetration of the needles without displacement of the woven fabric it has been found advantageous to retain the fabric under substantial tension during the needling operation.

In the preferred operation of the apparatus of the present invention with the needles of the shape illustrated in Figure 3 of the accompanying drawings, the needles are caused to pierce the fabric but not to extend any substantial distance beyond the supported rear surface of the woven fabric. The tips of the needles generally extend anything from about 0.5 millimetres to approximately 3 millimetres beyond the rear -2 3surface of the woven'fabric, and the action of all the needles *5 · · on the fabric should be similar. Such substantial uniformity in the effect of the needles on the woven fabric is obtained by accurate mounting of the needles in the needle board so that the tips of all the needles are caused to lie substantially in the same plane , and by providing the support for the rear surface of the woven fabric, which support is close and effectively continuous but penetrable by the needles without damage to them, It will be appreciated that the arrangement of the fibrillating apparatus illustrated in Figures 1 to 3 of the J » accompanying drawings is a preferred apparatus. While it is I most convenient for the needle board to be mounted above the woven fabric, which in turn is above the support which is the 1? leather, other arrangements are possible. For example, the woven fabric could be tensioned over the needle board which has the needles pointing upwardly and with the support for the l woven fabric above the woven fabrio. Alternatively, the fabric could be advanced in a vertical plane between the support and the needles of the fibrillating apparatus.

It is only by the practice of the present invention that the tapes which comprise the warp and weft components of the woven fabric have been really reduced to a multiplicity of fibrils whilst being relatively free of surface hairiness. 2? These features provide the marked improveih'ents in reduction in sheen, enhanced adherability, improved ability to impart colour, and reduction in needle deflection1'which have been described herein.

Claims (5)

1. Apparatus for treating a woven fabric which comprises a needle board, a multiplicity of smooth-surfaced needles of rounded cross-section mounted on the needle board with 5 the tips of the needles all in substantially the same plane and arranged at a density of at least 75 needles per square centimetre over at least a part of the surface of the needle board, means for reciprocating the needle board such that the nefedles are moved axially, and a support 10 capable of maintaining a woven fabric in a substantially planar configuration during reciprocation of the needle board such that the needles penetrate the warp and weft of the woven fabric, the support accommodating, without damage to the needles, the tips of the needles which penetrate the 15 woven fabric.

2. Apparatus according to Claim 1 wherein the needles are mounted on at least a part of the needle board in a density of about 120 needles per square centimetre.

3. Apparatus according to Claim 1 or Claim 2 wherein the 20 support comprises a base having thereon a covering of chromed leather.

4. Apparatus according to either Claim 1 or Claim 2 wherein the support includes a material which is fixed in position and the surface of which has therein holes formed 25 by the tips of all the needles of the needle board, the material of the support thus containing holes corresponding -25V in position to the tips of all the needles for receiving the needle tips during reciprocation of the needle board, and the material of the support member around the holes providing a support for the warp and weft components of a woven fabric placed thereon around the areas where the needles impact the woven fabric.

5. Apparatus for fibrillating warp and weft components in a woven fabric substantially as hereinbefore described with reference to Figures ί to 3 of the accompanying drawings.