CA1060639A - Apparatus for treating woven fabrics - Google Patents

Abstract

ABSTRACT

Apparatus is described for fibrillating a woven fabric comprising warp and weft tapes of polypropylene, such as is currently used as a primary carpet backing, by repeated needling of the fabric. The apparatus includes a needle board on parts of which needles of generally rounded cross-section, preferably circular cross-section, are mounted to a density, preferably of the order of 120 needles per square centimetre with the tips of all the needles in substantially the same plane. During the reciprocation of the needle board to fibrillate the warp and weft in the woven fabric, the fabric is maintained in a planar configuration by a support which accommodates the tips of those needles which penetrate the fabric without damage to the needles.

Description

1~60639 This invention relates to apparatus for fibrillating woven fabrics and is divided from our co-pending Patent Application No. 276,822. One particular example of an application of the apparatus of this invention is the fibrillation 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 fro~ "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. 276,822 there is described and claimed a woven fabric having warp and weft of synthetic resinous material, both the warp and weft having been fibrillated

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~01~0639 in situ in the woven fa~ric such that the surface 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 the 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 fibriis by fibrillation in situ in the woven fabric has a markedly different reflective property in its surface as comparQd 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 said co-pending Patent Application No. 276,822 are fibrillated by repeated needling thereof.

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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 fabrir 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.

~0 In accordance with the present invention there is provided apparatus for fibrillating a woven fabric which comp~ises a needle board, a multiplicity of smooth-surfaced needles of generally rounded cross-section mounted on the needle board with the tips of the needles all in sub-stantially 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 boar~ means for reciprocating the needle board such that the needles are moved axially, and a support --~ .

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 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 -higher order is used in apparatus in accordance with the present invention.

Advantageously, apparatus in accordance with the -~
present invention has needles mounted in a needle density over at least a part of the needle board of the order of 100 to 150 needles per square centimetre. In the specific ~ -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.
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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 cross- ~-section. 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-.;,, , .: . : , : , , : ; , ~ - , 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-sectiol~, 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 cross-section 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:-.

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Figure 1 is a s;de view of apparatus for treating a woven fabric of flat warp and weft tapes of polypropylene, Figure 2 is 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 is 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 Figures 6 and 7 are schematic flow diagrams showing the steps of alternative processe~ of making woven fabric~ 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 i5 shown in Figure l a woven fabric l 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 tape~, for example, having a width o~ the order of two and a half millim~es while the warp tapes have a width of the order of one and a quarter millimetres. ~he woven fabric l i9 advanced in the direction of an arrow 2 towards a ~ibrillating 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) i~ passed through the fibrillating apparatus 3 which may be generically described as a needling machines The fibrillating apparatu~ 3 is however different from a conventional needle loom in that it has a special needle board ~ and also a special ~upport which supportq the woven fa~ric l during operation of the needle board 4.

~he needle board 4 carrie~ needles 5 of circular cross-section, which are fine needles arranged on the needle board in dense group~ 5a, 5~, 5c etc. (see ~igure 1). ~ach group of the needles 5 contains four strips of needles 5 extending laterally acroqs the width of the fibrillating apparatu~ 3, as shown in ~igure 2, the needles in each ~trip being a row containing approximateIy 16 needles to eaoh centimetre length of the strip.

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The overall width of each group 5a, 5b, 5c e-tc. of nee~les is approximately 5 millimetres, with the result that each area of the needle board ~ which carries a grouy o~ needle~
5a, ~, 5c etc. ha~ the needles mounted in a density of the order of 120 per ~quare centimetre. There i9 a spacing o~
the order of lo millimetre~ between the separate groups 5_, ~, 5c etc. of needles.

A~ the woven fabric 1 is passed through the fibrillating apparatus 3 it is supported by a ~urface covering 6 on a solid base or bed 7.

The surface covering 6 used on the bed 7 is advantageou~ly chromed leather. When leather is used, the needle board 4 i~
preferably reciprocated to cause the needles 5 to perforate the ourface of the leather covering on the bed 7 in the absence o~ any woven fabric 1, thereby ~orming in the surface of the leather minute holes ~or receiving the tips o~ the needles 5 while the remainder of the sur~ace of the leather pro~ides a close support for the woven fabric 1 around the area~ where the needles 5 impact the woven fabric 1.
. . . -As the woven fabric 1 advance~ in a step by ~tep manner through the ~ibrillating apparatu~ 3, the needle board 4 i9 reciprocated at a su~ficient rate to impart 3,000 needle penetration~ per square centimetre.

~ In Figure 3 there is illustrated one of the needles 5 which are mounted densely on areas o~ the needle board 4 as illu~trated in Figure~ 1 and 2. The needle 5 has a circular ~cross-section.

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In operation of the ~ibrillating apparatus 3, at least the q 106063~
tips of the needles 5 are required to penetrate through the woven fabric l.

Variations in the finish produced by treatment of a woven fabric by the method of the present invention may be aohieved by adjusting the degree of penetration of the needle tips and the density o~ needling. The den~ity of needling i~
affected by the den~ity with which the needle~ are mounted in the apparatu~, and by the rate at which the woven fabric is adYanced through the apparatus in conjunction with the speed at which the needles are reciprocated by the apparatus.

The effect of repeated penetration o~ the warp and weft tapes making up the woven fabric 1 by the needle~ 5 i9 to make a large number of ~plit~ in each warp and weft tape 90 that, at any cro~-section through a warp or a weft tape, it is comprised of a multiplicity of fibrils. The consequence is that thelshiny surfaces which were prese~t in the warp and weft tapes as the wo~en fabric l approached the ~ibrillatingapparatu~
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 ~ibrils. 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 ~abric 1 emerging from the ~ibrillating apparatus 3 iB substantially reduced as compared with its reflectivity be~ore treatment in the fibrillating apparatus ~.

The wo~en fabric l which has been treated in the fibrillating apparatus 3 in accordance with the present in~ention has a relatively matt sur~ace as a result of the wo~en ~abric being compo~ed o~ warp and we~t eaoh o~ which has .. - --;4--been obtained by fibrillating a warp or weft tape in 9itU
in the woven fabric. ~ach warp or weft therefore compri~e~
a multiplicity of fibrils, which con~titute a flat bundle, giving a visual impression that the fibrils lie 3ubstantially 5 in the same plane.

The fibrillation of the warp and weft tapea o~ the woven fabric 1 by the action of the ~ibrillating apparatu~ 3, has the effect of causing the warp and weft to tend to spread ~o that, if such spreading is po~sible, the fibrils which compri~e each of the warp and weft after the fibrillating treatment have a greater combined width than the respective tape prior to the fibrillation treatment. Thi~ ~preading of the warp and weft element~ of the woven ~abric 1 in the fibrillation treatment is believed to be facilitated by cau~ing more than the tip~ of the 1~ neèdles 5 to penetrate the tape~ of the woven fabric.

Figures 4 and 5 of the accompanying~drawings illu~trate ths ~urfaee appearance of the woven fabric 1 before and after the treatment in a fibrillating apparatu~ 3.

Referring to Figure 4 there are shown warp tapes 11 and weft tapes 12 each ~ormed ~rom polypropylene. ~he surface~ o~
the tape~ 11 and 12 which are expo~ed in the woven fabric 1 are smooth and shing as a re~ult of the tape~ being derived Prom an extruded film o~ polypropylene. It will al~o be observed in Fi~ure 4 that there tend to be spaces between the warp tapes 11 and the weft tapes 12.

Re~erring now to Figure 5, the woven ~abric after the treatment by the ~ibrillating apparatu~ 3 has individual warp and weft 13 and 14 compri~ed of a multiplicity o~ fibrils which ,~_ ~060639 give the woven fabric of Figure 5 the appearance of a basket-wea~e, The breaking down o~ each tape 11 and 12 by splitting into a multiplicity of fibrils causes the ~urface of the woven fabric of ~igure 5 to be relatively matt as compared with the surface of the woven fabric of ~igure 4. Al~o the splitting of the individual warp tapes 11 and weft tapes 12 each into a multiplicity of fibrils causes both to ~pread with the re~ult that any gaps which previously existed between edges of the warp and weft component~ of the woven fabric 1 are ~ubstantially reduced.

In general the breaking-down of the warp tapes 11 and weft tapes 12 into the multiplicity of fibrils which compri~e the warp 13 and weft 14 will cause the resultant warp and weft component~ to have a greater width than the original tapes as described' above at least where the warp and weft constitute the exposed sNrface of the woven fabric 1, e~g. where a warp i~
supported by a we~t. However, the ability of the warp and weft to spread may be restricted in fabrics which ha~e a close initial construction.
' The treatment in accordance with the present invention to break down each warp and weft into a multiplicity o~ fibrils may ~e effected with a lesser number o~ needle penetration~ -~
than 3,000 per square centimetre.

There will now be given examples of woven fabrics which are treated by fibrillating warp and weft tape~ in situ in the woven fabri¢.

A woven fabric was formed from warp and weft tapes of .

polypropylene which were both of generally rectangular cro~-section, The warp tapes, drawn at a draw ration of 6:1, were approximately one and a quarter millimetre~ in width, the weft tapes, drawn at a draw ratio o~ 7sl, had a width o~ approximately two and a hal~ millimetres, and both warp and weft tape~ had a thickne~s ~f the order o~ 50 micron~, the warp tapes being approximately 500 denier and the weft tape~ being approximately 1,000 denier, In the woven fabric ~ormed ~rom these warp and weit tapes there were 94 warp ends per 10 centimetres and 51 we~t ends per 10 centimetree.

Each square oentimetre o~ this woven fabric was subjected to about 3,000 needle penetrations u~in~ the fibrillating apparatus 3 described above with reference to Fi~ure~ 1 to 3 of the drawings. The re~ultant product i~ a woven iabric having warp andlweit each oomprised by a flat ~undle of iibrils, the individual ~ibril~ being generally rectangular in cro~s-section.
~he warpj component~ are compri~ed of fibrils of 40 denier a~erage with a range ~rom 13 to 70 denier, while the weft component~ are comprised o~ fibril~ oi 27 denier ~verage with ~ a range from 8 to 50 denier.

~ha ~ibrillated woven ~abric whlch i~ the product of ~ ~-Example ilwas passed through the fibrill ting apparatu~ 3 in similar ~nner on two further occa~lens. ~he resulting woven 2g ; ~bric~ whioh had been aubjected to about 10,000 needle penetrati~ns per square centimetre, wa~ a markedly softer cloth than the product of Example 1. ~ ~
f Examination oi tha woven ~abric which had been subjected to about 10,000 needle penetrations per square centimetre showed ..
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1~:)60639 that a chan~e in the shape of the fibrils in thi~ cloth had occurred as compared with the product of Example 1, The product of this present example was a woven fabric composed o-f fibrils having a lower a~erage den'ier and many of the fibrils had portions which were no longer rectangular in cros~-~ection du,e to corners having been removed.

The ~ibril~ o~ the warp components of the wo~en fabric resulting from 9,000 needle penetrations per ~quare centimetre were on average of 18 denier and ranged ~rom 6 to 35 denier.
~he fibrils of the weft components were on average of 11 denier and ranged between 7 denier and 18 denier.

EXAMP1E ~
Subjection of the product of Example 2 to two further pa~ses through the fibrillating apparatus 3 ~o that each square centimetre o~ the woven fabric was ~ubjected to approximately ~' ,ooo ne,edle penetrations produced a further softening,in the re~ulting product.

' EXAMPIE 4 Polypropylene tapes of approximatelg 1,000 denier were uYed a9 both warp and weft in the weaving of a woven fabric having 39 ~' warp ends per 10 centimetres and 51 weft end~ per 10 centimetres.
Thi~ wove~ fabric wa~ then fibrillated using the fibrillating apparatu~'3 described above in o~der to subject each ~quare ~ centimetre of the woven fabric to about 10,000 needle penetrati~n~

~he products of Examples 2 and 3 are woven fabrics based on , syntheti¢ re~inou~ material (polypropylene) which have been obtsined by ~ procee~ which is sub~tantially cheaper than the : ,.
i4 known conventional methods of producing a cloth of similar handle and propertie~ from synthetic fibre~. The product of Example 4 which i~ a woven ~abric obtained by weaving tape~ -o~ l,Ooo denier polypropylene, with 39 warp end~ per 10 centimetres and 51 we~t end~ per 10 centimetres followed by -the ~ibrillating treatment of the present invention i9 a cheaper manufacturing proce~ than that of weaving from synthetic fibre~ a fabric having, ~or in~tance, ~ome 200 or 250 warp and we~t end~ per 10 centimetre~.

The woven fabric of Example 1 above and which ha~ the form illustrated in ~igure 5 posse~e~ a sub~tantial a~vantage with regard to the adhe~ion to it of material ~uch a~ a latex.
It is known to attach to a woven fabric such a~ that illustrated in Figure 4, when intended for use a~ a conventional carpet backing m~terial, a coating or layer o~ latex in order to give the woven ~abric a resi~tance to distortion, that is to ~ay a re~i~tance to de~ormation of the woven fabric from an overall reotangular ~hape towards a parallelogram or diamond shape.
Howe~er, polypropylene is an hydrophobic material, and the surface~ of the polypropylene tape~ which compri~e 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 i~ secured to the woven fabric of ~igure 4 by a mechanical interlocking or keying of the latex into the gaps 2~ between the warp and weft tape~ of polypropylene, and in order . , .
to o~tain thi~ mechanical keying of the latex to the fabric a relati~ely thick coating of latex i~ nece~sary.

HoweYer, the product of Example 1 and Figure 5 ha~ a much greater ~acility for adhering a coating, for example a . .
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~060639 latex, to the woven fabric. The fibrils in the warp and weft 13 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 ~igure 5, with a much lesser ~hickness than is necessary in order to secure a latex covering to the woven fabric of ~igure ~. It ha~ al~o been found that a more uniform spreading of the latex can be achieved.

This ha~ a significant advantage in economy in the quantity of latex u~ed. There is a further advantage in that - 10 the thinner layer o~ latex which may be u~ed to prevent mechanical di~tortion of the woven fabric of Figure 5 may be pierced relatively ea~ily by a tu*ting needle when the woven fabric i~ u~ed as a carpet backing material. Thi~ iB in contrastlto the difficulty which the tufting needle has in piercingi!the woven fabric of Figure 4 9 which requixes the substantially thicker coating of latex in order to obtain adherence between the latex and the fabric, with the result that the tu~ting needle i8 liable to punch holes in the fabric, and ~ thereby damage the backing material.

~ A iurther and very important advantage which i~ provided by the woven fabric of Figure 5 is the ability to impart colour tola woven fabric based on polyprdpylene. Hitherto it ;
has been olne of the major di~advantages o~ woven ~abrics ba~ed on polypropylene, when used as carpet backings, that they have a poor dye characteristic and in consequence the backing material i~ particularly likely to ~how up through dyed yarns which con~titute the pile of the carpet. The present Appli¢ants have found that the woven fabric treated in the manner de~¢ribed in accordance with the present invention, and . "'' . ' . ~ , . .

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` :1060639 as illustrat~d in Figure 5, may be readily rendered dyeabl~ by appropriate dyestuff~. ~his i8 achieved by applying to the woven fabric of Figure 5 a latex which has the ability to be dyed. ~atex having the ability to be dyed, for instance by an acid dyestuff (hereinafter referred to a~ "aoid-dyeable latex")~
i~ obtainable, for example, from Rohm & Haas. ~he latex iB
applied to the woven fabric of Figure 5 by any ~uitable method, for example~ by spraying or by using a doctor blade or by passage of the woven fabric in contaot with the upper suriace oi a roller the lower surface of which i~ pas~ing through a bath of the dyeable latex. An applicator 15 ~or applying the dyeable latex i3 shown diagrammatically in Figure 6, which is a ~low diagram illustrating this aspect o~ the present invention.
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The Applicant~ have made comparatlve tests in which similar quantities oi acid-dyeable latex ha~e been applied to the wo~e~ ~abric~ of ~igures 4 and 5. T~ese te8t8 have shown that, when the two woven fabrios, each carrying similar layer~
o~ aoid-dyeable latex, are treated in a bath oi acid dye~tuff, the wove~ fabric of Figure 4 shows littl'e overall coloration, whereas a significant and uni~orm depth o~ colour appears in the lutex'-coated woven ~abrio oi Figure 5. Good ooloration of the wo~en ~abric o~ Figure 5 ha~ been ob~ained wlth an addition of only about 12~ by we~ght oi the acid-dyeable latex.
- 2~ Accordingly the woven iabric of ~igure 5 with the acid-dyeable latex is suitable ~or uae a~ a primary bapking for tufted oarpets of which the plle is a material ~ch as polyamide which ie ~ubsequently dyed using an acid dyestu~ff.
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-~ ~ Examination of the woven iabrio of Figure 4 a~ter -a~ ! ! .

10~i0639 treatment with an acid dye~tu~f show~ that such coloration a~
i~ present occurs principally at the edges of the polypropylene tapes which comprise the warp tape~ 11 and the weft tapes 12.
It i9 believed that the very marked improvement in coloration which occurs a~ a result of the acid dye treatment of the woven fabric of ~igure 5 a~ter coating with acid-dyeable latex i~ a consequence of the presence of a multitude of edge ~urface~
in the polypropylene material which makes up the warp and weft 13 and 1~ as a re~ult of the fibrillation of the warp and weft tape~ during the pas~age o~ the woven fabric 1 through the fibrillating apparatu3 3.

Acc!ardingly, the woven fabric of ~igure 5, in which the warp and!weft 13 and 14 are broken down so that each warp or weft i~ essentially a flat bundle o~ fibrils, i~ a backing material 1~ for use i!n the manufacture of tufted carpets which may be employed,succe~sfully to reduce the incidence of grinning. l:

.~ However, the woven fabric of Figure ~ which pre~ent~
a large number of edge sur~aces to the fibril~ in the warp and .~
weft 13 and 14 iP also found to be capable of coloration by ~ -. 20 dyeing i~ the woven fabric is made from ~ dyeable ~ynthetic : resinous material such a~ a polyester, a polyamide, a polyacrylonitrile, a polyvinyl alcohol, a polyvinyl chloride, a cellulo~e aoetate or a viscose material. The woven fabric .~ which i9 the product of Figure 5 is al~o dyeable when made o~ a 25 generally non-dyeable ~ynthetic re~inou~ material if a dyeable component is incorporated in the generally non-dyeable synthetic resinous material, such a5 polypropylene, before this material is extruded and formed into tapes, woven into a fabric and then . ~ ~ibrillated.

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~0~0639 ~ igure 7 illustrates a flow diagram for carrying out thi process. It ha3 been found that, when a disperse dyeing agent is included in the polypropylene from which the woven fabric i~ made, the woven fabric which is the product of Figure 5 i9 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 ~. The product of Figure 4 takes up some colour but not a great deal; thq coloration of the product of Figure 4 has not been adequate for many uises of the woven fabric, including its use as a primary carpet backing.

Another method o~ applying coloration to the woven fabric l, the warp and weft components of which are fibrillatea using the fibrillating apparatus 3, is by adding pigment to the synthetioi resinous material (for example'polypropylene) when this material i9 extruded. Such a pigmehted woven fabric when fibrillated to produce the product of ~ ure 5 has particular use as a furniishing fabric or a wall fabric as a result of the -~ ~ 20 matt fini~h which i~ much preferable to the shiny finish.
, : ~' As already indicated a woven fabric 1 in accordance with the present invention and as illustrated in Figure 5 has sub~tantial advantages when used as a primary backing for ~-~' tufted fabric. One of the most i~ignificant advantages is a substanti~l improvement in the overooming'~of the defect known a3'needlelde~lection, which will be aiscus~ed further in relation t:o the product~ of Figures 4 and'~5.

In the woven ~abric o~ gure ~ there tend to be spaces .

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106C)639 between the warp tapes 11 and the we~t tapes 12 90 that there are four po~sibilities facin~ the tufting needle which strikes the woven fabric of Figure ~, The tufting needle may ~trik:e a warp tape 11 in a position where it i~ 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 po~ition where the w~rp 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 con-~equence of this considerable variation in the possibility facing the tufting needle, the tufting yarn which is secured to the woven fabric of Figure 4 in a tufting operation will .
have an uneven pile ~urface.

In ~he wo~en fabric of Figure 5 the warp and weft have been broken down into a multiplicity of fibrils and are l; -less lia~le to needle deflection ~ince the needle ha~ a much greater chance of striking into a gap between fibrils. In :~ consequence the woven fabric of ~igure 5 presents less variety to the tufting needle than the woven fabrlc of Figure 4 and : gives a more level pile surface to the final tufted carpet than that obtained by the tufted carpet produced from the conventio~al woven fabric of Figure ~.

Beca~e of the substantial decrease in the reflectivity 25 ~ ~ o~ the sur~aces of the warp and weft components which make up the , : woven fabric as a re~ult of the treatment in accordance with the present invention, the woven fabric of. Figure 5 i~ a more .~.
~ac¢eptable ~orm of backing material for tu~ted carpets. ~ :

: When the woven fabri¢ of Figure 5 i9 tufted in order to :
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~06(~639 produce a tu~ted carpet, it provide~ a more regular and con~istent spacing of the tuft lines than i9 obtained by tufting the woven fabric of ~i~ure 4. ~hi~ is becau~e the surface o~ the woven ~abric of ~igure ~ i~ a relatively good acceptor of the tufting needle in the sense that, wherever the tu~ting needle strikes the surface of the woven fabric of Figure 5, it will be able to penetrate between adjacent fibrils without causing any ~ignificant needle deflection. The tuft~
of yarn will thu~ be located at ~ub~tantially the places where the tufting needles strike the surfaces of the woven fabric.
By contra~t, the woven fabric of Figure 14 is not a good acceptor`o~ the tu~ting needle becau~e the tu~ting needle mu~t itself break through the sur~ace of a warp tape 11 or a we~t tape 12, and in ~ome cases ~particularly near the edges 1~ o~ the warp and weft tape~) the tufting needle will fail to do thi~, but will deflect the warp or weft tapes to one eide 80 that there will be an uneven ~pacing between that " . I
psrticular tuft of yarn and the adjacent tuft.

When a woven fabric which i~ intended for use a~ a ~ carpet backing i~ fibrillated in accordance with the pre~ent . . . .
invention the fibrillating treatment may be applied to -the main central part of the woven fabric but ~trips down the opposite edge portions of the woven fabric may be left untreated. ~he purpose of leaving edge portions of the woven ~ab~ic untreated is to retain in tho~e edge portion~
good prop~rties for enabling the woven ~abric to be mechanically pinned during later treatmenb t the untreated portion~ being eventually trimmed from the woven fabric before I' ~ the-final carpet product i~ rolled.
.; ~ . , ~_ ~060639 The fibrillation of the tapes in a woven fabric of synthetic resinous material ~uch as polypropylene 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 proces~ the woven fabric i~
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 needle~ being kept clear of the surfaces of the tape~. The purpose of tlp-needling was to try to break-up the tapes in order to allow for more preci~e acceptancle of the tufting needle and thus reduce the 'incidence of needle deflection, but in practice the u~e of 1~ tip-needling ha~ increased the expense in producing the woven carpet backing without even being entirely successful in eliminating needle deflection. ~urthermore the surfaces of the carpet backings after treatment in a tip-needling process have ~ ~ retained their ~heen and it ha~ proved difficult to distinguish a tip-needled backing from one which ha~ not been ~ubjected to ..
th1s treatment. ~ ' It is thought that there are two main reasons why the .
~- known tip-needling proces~ ha~ not produc~d the advantageous ` ~ re3ults ~rovided in accordance with the present invention.
~irstly, the tip-needling has been carried out with needle~
which hav~ a triangular ~ection. Secondly, the density of i'~ ' the perforations effected in a tip-needlihg proce~s ha~
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 o~ the present invention , :

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which, as previously stated, i~ at lea~t 800 per square centimetre and preferably at least 1,800 per square ce~timetre.

Another significant difference between the fibrillating apparatus as described in the present Specification and the known needle loom is the nature o* the support for the fabri.c while it is being treated by the n.eedle~ of the fibrillating apparatu~. In accordance with the present invention the base support, e.g. chromed leather, provides a clo~e ~upport against the back ~ur~ace of the woven ~abric, so that the fabric is effectively supported, but at the same time the support material is able to accommodate the tips o~ the needles without damage to the needles o~ the fiblrillating apparatu~.
The supp!ort which is provided in a conventional needle loom consists,of a metal plate which ha~ provided a hole or slot to 1~ accept each of the needles. The complexity of providing such a metal plate in a fibrillatin.g apparatu~ according to the presen.t invention is enormous and thought to be impraotical.

In order to facilitate the penetration o~ the needles ,' : ~ without displacement of the woven fabric it has been found , ''~
' 2Q ' ad~antageous to retain the fabric under ~ubstantial tension '~
during the needling operation.

In the preferred operation of the apparatus o~ the ~ present invention with the nsedles of the shape illustrated -~ in ~igure 3 of the accompanying drawing~, the needles are ; ~5 ¢aused to pierce the fabric but not to extend any ~ubstantial : dlstance beyond the supported rear surface of the woven fabric. ;' The tips o~ the needles generally extend anything from about Q~.5 mlllimetreB to approximately 3 millimetrea beyond the rear ~ ' :

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~urface of the woven fabric, and the action of all the needles on the fabric should be similar. Such ~ubstantial uniformity in the effect of the needles on the woven fabric is obtained by accurate mounting of the needle~ in the needle board 80 that the tips of all the needles are cau~ed to lie ~ub~tantially in the same plane, and by providing the support for the rear surface of the woven fabric, which support is close and effectively continuou~ but penetrable by the needle~ without damage to them.

It will be appreciated that the arrangement of the fibrillating apparatu~ illustrated in Figures 1 to 3 of the accompanying drawings is a pre~erred apparatus. While it is mo~t con~enient for the needle board to be mounted above the woven fa~ric, which in turn is above the support which is the 1~ leather,'other arrangements are po~sible. For example, the woven fabri¢ could be tensioned over the needle board which ha~ the needle~ pointing upwardly and with the support for the - woven fabric above the woven fabric. Alternatively, the fabric ~ could be advanced in a vertical plane between the ~upport and the needles of the fibrillating apparatus.

It is only by the practice of the p~e~ent invention that the tapes which comprise the warp and weft component~ of the woven fabrlic have been really reduced to a multiplicity of ~ibrils whil~t being relatively free of ~urface hairine~s.
25~ The~e feature~ provide the marked improve~ents in reduction in ~heen, enhanced adherability, improved ability to impart ¢olour, and reduction in needle deflectio~\ which ha~e been de~cribed ~erein.
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Claims (5)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. Apparatus for fibrillating a woven fabric which comprises a needle board, a multiplicity of smooth-surfaced needles of generally rounded cross-section mounted on the needle board with 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 needles are moved axially, and a support capable of maintaining a woven fabric in a substantially planar con-figuration 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 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 the order of 120 needles per square centimetre.

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

4. Apparatus for fibrillating a woven fabric which comprises a support member for the woven fabric, a needle board, a multiplicity of smooth-surfaced needles of generally rounded cross-section mounted on the needle board with the tips of the needles all in substantially the same plane and arranged in the groups of rows extending transversely to the support for the woven fabric with spacing between said groups, said needles having 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 said support member providing an effectively continuous support for a surface of a woven fabric placed thereon and whose surface is penetrable by the tips of the needles during a needling operation without damage to the needles, whereby the woven fabric is maintained in a substantially planar configuration during reciprocation of the needle board and means for advancing the fabric through the fibrillating apparatus in a step by step manner.

5. Apparatus for treating a woven fabric which comprises a needle board, a multiplicity of smooth-surfaced needles of generally rounded cross-section mounted on the needle board with 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 needles are moved axially, and a support member which includes a material which is fixed in position and the surface of which has therein holes formed by the tips of all the needles of the needle board, the material of the support member thus containing holes corres-ponding in position to the tips of all the needles and the material of the support member around the holes providing a support for a woven fabric placed thereon around the areas where the needles impact the woven fabric such that the surface of the support member provides an effectively continuous support for all areas of the woven fabric which are not impacted by the needle of the needle board.