A YARN FOR SYNTHETIC TURF AND A SYNTHETIC TURF

FIELD OF THE INVENTION

The invention relates to a tuftable yarn for synthetic turf and method for forming the yarn. The invention includes a synthetic turf comprising the yarn tufted into a backing layer of the synthetic turf to produce the grass-like pile filaments of the turf.

BACKGROUND TO THE INVENTION

Synthetic turf is a commonly used alternative to natural grass for sports playing fields, landscaping and many other applications. Synthetic turf typically comprises a flexible backing layer, such as a synthetic fabric, into which a synthetic yarn is tufted in rows to form a pile of grass-like filaments. The pile filaments of the synthetic turf are referred to in the industry as synthetic ribbons, tufts, or pile elements.

Synthetic turf surfaces can be manufactured to various specifications to suit different end applications. For example, depending on the end application, the length of the pile filaments from the backing layer, known as the "pile height", the spacing between rows of pile filaments or tufts, known as the "gauge", and the synthetic materials that are utilised to form the backing layer and synthetic yarn, can all be varied or selected to suit the end application. Tufting machines used to manufacture synthetic turf typically comprise a row of spaced needles each receiving a tuftable yarn for repeatedly punching through the backing layer to form rows of tufts on the backing layer, which define the pile. The tuftable yarn is typically formed from a synthetic material, such as polypropylene, polyethylene, nylon or the like. One commonly used type of yarn is referred to as a monofilament yarn.

Monofilament yarns typically comprise a bundle of individually shaped extruded monofilaments that are twisted or wrapped together to form a tuftable yarn package.

Conventionally, monofilament yarns are produced by forming individually shaped monofilaments by extrusion through a die head or spinneret. The spinneret typically comprises around 100 individual orifices each for extruding an individual monofilament. The individual die orifices and thus monofilaments can have a variety of shapes and sizes depending on the profile of each individual die orifice of the spinneret. After extrusion, the monofilaments are cooled in a quench bath and can be subjected to various processes in

order to finish the monofilaments to the required construction and dimension. One or more monofilaments are then cross wound on to a cone in preparation for the next step in the yarn manufacturing process.

The next step is known as sampling. Typically the desired number of filaments for a yarn are wound together on to a single cone. The number of filaments required typically varies between 3 and 10 monofilaments. At this stage, different individual monofilament types or colours can be mixed together.

The filaments are then put through a twisting machine that twists the bundle of individual monofilaments together into a neat package that constitutes the tuftable monofilament yarn. Typically, the number of twists is between 25 and 50 turns per metre. Twisting the individual monofilaments together aids subsequent tufting of the yarn into the backing material as a bundle of untwisted monofilaments is very difficult to tuft effectively. The twisted monofilament yarn is then cross wound on to a bobbin ready for tufting by the tufting machine. As an alternative to twisting, the untwisted bundle of monofilaments can be wrapped together with a thin bulk continuous fibre strand. This again presents the bundle of individual monofilaments as a neat package for tufting of a wrapped monofilament yarn.

Subsequently, to manufacture a synthetic turf, the wrapped or twisted filaments are tufted into a fabric, commonly known as the primary backing. Needles containing the yarn penetrate the primary backing material. The yarn is caught by a hook on the other side of the primary backing in order to form a loop. The loops are then cut to form a 'U' shaped tuft, which releases the twist from the filaments. The cutting action also reverts the filaments to individual non-twisted or non-wrapped filaments, which gives a natural looking grass blade-like effect. To lock the filaments into the primary backing material, a coating of either a latex compound, polyurethane, or similar is applied to the underside of the backing and dried or set, to cover the back stitches. The coating holds the individual filaments in place with the objective that no filaments can be pulled from the finished turf. However, to achieve this, the coating material must contact and hold all individual filaments. Figure 1 shows a typical profile of a single tuft containing monofilament fibres 1 tufted into a primary backing material 2 and covered on the underside with a coating material 3. Note that the coating material 3 will generally only contact the lower or outer

filaments of each tuft. The coating frequently does not penetrate to 4 and as a result the upper or inner filaments are not secured to the primary backing 2 and may pull out.

In this specification the foregoing background information is given for the purpose of providing a context for discussing features of the invention. Unless specifically stated otherwise, it is not to be construed as an admission that such information, in any jurisdiction, is prior art, or forms part of the common general knowledge in the art.

It is an object of the present invention to provide an improved tuftable yarn and/or an associated synthetic turf, or to at least provide the public with a useful choice.

SUMMARY OF THE INVENTION

In a first aspect, the present invention broadly consists in a tuftable yarn for synthetic turf comprising two or more individual monofilaments, each monofilament being connected to one or more other monofilaments by a co-extruded frangible web. In one form, the individual monofilaments may have an identical cross-sectional shape. In an alternative form, the individual monofilaments may comprise monofilaments having two or more different cross-sectional shapes.

In one form, each frangible web may have minimal width such that the connected monofilaments are integral at a line along their length. In another form, each frangible web may comprise a discrete region of identifiable width relative to the monofilaments it connects. Preferably, each frangible web may have a width that is narrower than the corresponding dimension of the monofilaments it connects in the same orientation. More preferably, each frangible web may have a dimension in an orientation transverse to its width that is less than the corresponding dimension of the monofilaments it connects. Preferably, each frangible web may be continuous along the length of the yarn.

In one form, each or some of the monofilaments may have a solid cross-sectional area. In an alternative form, each or some of the monofilaments may comprise one or more hollow regions within their cross-sectional areas.

Preferably, the yarn is extruded from a polymeric material. Preferably, the tuftable yarn comprises at least four monofilaments.

In one form, the individual monofilaments may be formed in a side-by-side relationship thereby forming a tuftable yarn having an overall width that is greater than its overall thickness.

In a second aspect, the present invention broadly consists in a die head or spinneret (herein: spinneret) for producing a tuftable yarn for synthetic turf, the spinneret comprising two or more die orifices for extruding therefrom two or more monofilaments, and a connecting orifice of lesser dimension for co-extruding with the monofilaments a frangible connecting web between the monofilaments.

In one form, the die orifices may have an identical cross-sectional shape. In another form, the die orifices may comprise orifices having at, least two different cross- sectional shapes.

Preferably, adjacent die orifices are connected by a connecting orifice so as to form a co-extruded frangible connecting web between the adjacent monofilaments during extrusion of the tuftable yarn. In one form, each connecting orifice may be of minimal width such that the connected die orifices are integral at a line along their length. In an alternative form, each connecting orifice may have a discrete region of identifiable width relative to the die orifices it connects. Preferably, each connecting orifice may have a width that is narrower than the corresponding dimension of the die orifices it connects in the same orientation. More preferably, each connecting orifice may have a dimension in an orientation transverse to its width that is less than the corresponding dimension of the die orifices it connects.

Preferably, the spinneret may comprise multiple groups of two or more die orifices with connecting orifices between the die orifices of each group, and wherein each group forms a separate tuftable yarn. Preferably, the or each group of die orifices of the spinneret may comprise at least four die orifices for extruding therefrom four monofilaments, and at least tiiree connecting orifices for co-extruding frangible connecting webs between the monofilaments.

In one form, the die orifices may be arranged in a side-by-side relationship such that the overall width of the extruded yarn is greater than its overall thickness. In a third aspect, the present invention broadly consists in a method of producing a yarn for synthetic turf which comprises extruding one or more monofilaments with a frangible connecting web between the monofilaments.

Preferably, the step of extruding two or more monofilaments with a frangible connecting web between the monofilaments may comprise extruding polymeric material through a spinneret, the spinneret comprising two or more die orifices for extruding the two or more monofilaments, and a connecting orifice of lesser dimension between the die orifices for forming the frangible connecting web.

Preferably, the monofilaments and connecting web(s) are integrally formed from a single material.

In a fourth aspect, the present invention broadly consists in a synthetic turf comprising a backing material and rows of spaced tufts of pile filaments, at least some of the tufts comprising pile filaments connected to each other at or behind the backing material by a web or webs co-extruded with the filaments

In one form, each web may be of minimal width such that the filaments are integral at a line along their length in the region of die web. In another form, each web may have a discrete region of identifiable width relative to the filaments. Preferably, each web may have a width that is narrower than the dimension of the connected filaments in the same orientation. More preferably, each web may have a dimension in an orientation transverse to its width that is less than die corresponding dimension of the connected filaments.

In one form, the filaments of each tuft may have an identical cross-sectional shape. In an alternative form, the filaments of each tuft may comprise filaments having two or more different cross-sectional shapes.

In one form, die tufts of filaments extend above the backing material by a pile height, and wherein at least some of the tufts may comprise pile filaments that are connected to each other by co-exturded webs that extend from behind the backing material to above the backing material for a minor portion of the pile height of the tufts such that the filaments are unconnected for a major portion of the pile height from dieir free ends.

In an alternative form, the tufts of filaments extend above the backing material by a pile height, and wherein at least some of the tufts comprising pile filaments that are connected to each other by co-extruded webs that extend from behind the backing material to above the backing material for a major portion of the pile height such that the filaments are unconnected for a minor portion of the pile height from their free ends.

Preferably, the synthetic turf may further comprise a granular infill material between the tufts and above the backing material.

In a fifth aspect, the present invention broadly consists in a method for forming a synthetic turf comprising extruding two or more monofilaments with a frangible connecting web between the monofilaments to form a tuftable yarn, forming rows of spaced tufts of pile filaments in a backing material with the tuftable yarn, and subjecting the tufts to mechanical processing to break the frangible connecting webs between at least some of the monofilaments of some of the tufts on one side of the backing material, while leaving intact behind the backing material the web or webs between the filaments.

Preferably, the step of subjecting the tufts to mechanical processing may comprise subjecting the tufts to a rotating tool having protrusions extending from its periphery that are arranged to break the frangible connecting webs between at least some of the filaments of some of the tufts on one side of the backing material. In one form, the method may comprise the step of moving the synthetic turf relative to the rotating tool in order to break the frangible connecting webs between at least some of the filaments of some of the tufts on one side of the backing material. In another form, the method may comprise the step of moving the rotating tool across one side of the backing material while the synthetic turf is fixed in place in order to break the frangible connecting webs between at lest some of the filaments of some of the tufts on one side of the backing material. Preferably, the rotating tool may be a rotating brush. In this specification and claims, the term "frangible" in relation to the connecting webs is intended to mean easily broken by mechanical means, such as by brushing the turf as will be subsequently described. The width of the frangible web between any two monofilaments will typically be lesser than the dimension of the monofilaments in the same orientation but may be greater, but the dimension of the frangible web in an orientation transverse thereto will be less than the corresponding dimension(s) of the monofilaments, to ensure that when the subjected to mechanical means to separate the monofilaments, the connecting web will break before the monofilaments.

The term "comprising" as used in this specification and claims means "consisting at least in part of. When interpreting each statement in this specification and claims that includes the term "comprising", features other than that or those prefaced by the term may also be present. Related terms such as "comprise" and "comprises" are to be interpreted in the same manner.

The invention consists in the foregoing and also envisages constructions of which the following gives examples only.

BRIEF DESCRIPTION OF THE DRAWINGS Preferred embodiments of the invention will be described by way of example only and with reference to the drawings, in which:

Figure 1 shows in schematic cross-section a single tuft of turf in a backing material with a coating on the underside thereof (prior art),

Figure 2A is an enlarged schematic cross-section view of one embodiment of a synthetic turf yarn of the invention having monofilaments linked by frangible webs having minimal width,

Figure 2B is an enlarged schematic cross-section view of another embodiment of a synthetic turf yarn of the invention having monofilaments linked by frangible webs having an identifiable width, Figure 3 is an enlarged schematic cross-section view of another embodiment of a synthetic turf yarn of the invention,

Figure 4 is a schematic cross-section view similar to Figure 1, of a single tuft of turf in a backing material, formed from a synthetic turf yarn of the invention and after brushing of the tuft to release the individual monofilaments, as will be further described, Figure 5 schematically illustrates brushing of a section of synthetic turf formed according to the invention, to release the individual monofilaments of the tuft,

Figures 6A to 6D show in enlarged schematic cross-section other synthetic turf yarns of the invention, and

Figures 7A to 7L show a number of possible cross-section shapes for individual monofilaments of synthetic turf yarns of the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Figures 2A and 2B show in cross-section two embodiments of a synthetic turf yarn of the invention, which comprises four monofilaments each having an oval shape. Obviously, the yarn is of indefinite length and has constant cross-section over its length. In accordance with the invention, each of the individual monofilaments 1 is linked to an adjacent monofilament by a line or web 5. Those monofilaments 1 having another monofilament on either side i.e. the inner two monofilaments, are linked to the

monofilaments on either side by a web 5, which may be a discrete region of identifiable width (Figure 2B) relative to the two monofilaments which it connects or may be of minimal width (Figure 2A) in that the two monofilaments are integral at a line along their length and the term "web" is to be understood accordingly herein. The yarn is produced by extruding a polymeric material from which the yarn is to be formed e.g. polypropylene, polyethylene, a polyester, Nylon or similar, through a spinneret having multiple die orifices, each die orifice forming one of the monofilaments 1. In the preferred form, the monofilaments 1 of the yarn are integrally formed, from a single material, without, for example, any other core material in the monofilaments. The die orifices are positioned closely together and connected by connecting orifices between the die orifices. The connecting orifices form the webs 5. That is, the webs 5 are co-extruded with the individual monofilaments 1, so that after exiting the spinneret the yarn comprises two or more monofilaments each connected to an adjacent monofilament by a web which is typically a continuous web. The webs are formed so as to be frangible by mechanical means such as brushing as will be further described, but have sufficient strength that their integrity is maintained during subsequent handling including in particular tufting of the monofilament yarn into a backing material to form a synthetic turf.

It will be appreciated that the spinneret may be arranged to produce a single tuftable yarn or multiple tuftable yarns of the invention. For example, if the spinneret is arranged to produce more than one tuftable yarn, it comprises multiple groups of two or more and preferably four or more die orifices with connecting orifices between the die orifices of each group, such that each group produces a tuftable yarn of the invention.

Figures 3 and 6 show other embodiments of synthetic turf yarns of the invention, each comprising a number of individual monofilaments connected lengthwise. The cross- section shape of each monofilament may be the same as the other monofilaments of the yarn as in Figures 2A and 2B, or different as in Figures 3 and 6. By way of example,' Figures 7A to 7L show a number of possible cross-section shapes that may be used for individual monofilaments as desired, and correspondingly for the spinneret orifice or orifices for forming the individual monofilaments. As shown in Figure 3, the individual monofilaments are preferably arranged in a side-by-side relationship such that the overall width X of the tuftable yarn is greater than its overall thickness Y. However, it will be appreciated that the individual monofilaments 1 do not necessarily have to be connected in a side-by-side relationship and other arrangements are possible. For example, the

individual monofilaments could be connected in a circular-type arrangement such that each monofilament is connected on either side to adjacent monofilaments, or other interconnected arrangements are possible.

By way of example only and with reference to Figures 7A to 7L, Table 1 sets out a number of possible cross-sectional shapes that may be used for the individual monofilaments, although it will be appreciated that any other suitable cross-sectional shape may alternatively be used. The individual monofilaments may have a solid cross-section or alternatively may have one or more hollow regions as shown in Figure 71.

Table 1

Once the yarn has been formed it may be spooled for subsequent use in manufacturing a synthetic turf. It is not necessary to twist the individual monofilaments of the yarn together or wrap them with a separate filament, as described previously.

In preferred embodiments, the individual monofilaments of the yarn may have a widest transverse dimension between 0.25 to 5 mm for example, and the yarn may comprise at least two monofilaments, and typically at least four or more monofilaments. It will be appreciated that the number of monofilaments provided in the tuftable yarn may be varied as desired.

By way of example only, the dimensions of the oval monofilaments 1 and frangible webs 5 of the embodiment shown in Figure 2B will be described. In this embodiment, the width of each monofilament 1 in dimension W is approximately 1.25mm, and the thickness in dimension T is approximately 0.175mm. With reference to the same dimension orientations, the frangible webs 5 have a width of approximately 0.25mm and a thickness of approximately 0.025mm.

It will be appreciated that the width and thickness of the monofilaments and frangible webs may be varied as desired and their dimensions are selected based on the overall yarn design. For example, the structure and dimensions of the frangible webs may be varied to suit characteristics of the yarn such as, but not limited to, the cross-sectional shapes of the monofilaments, the number of monofilaments in the yarn, and the polymeric material forming the yarn. Further, it will be appreciated that the frangible webs within a yarn need not necessarily be identical in cross-sectional shape or dimensions and may be varied depending on the shape of the monofilaments being linked. To form a synthetic turf, after forming the yarn, the yarn is tufted into a backing material in the conventional way, and the yarn loops cut to form the cut tile synthetic turf. In accordance with the invention, the exposed yarn strands, each comprising a number of monofilaments still connected by individual webs, on one side of the backing material are subjected to mechanical processing effective to break the frangible links 5 or between the individual monofilaments of the turf yarn, or to do so for at least some and preferably most of the individual tufts. The back stitches of the tufts on the other side of the backing material are covered with a coating material 3 to fix the tufts in place. It will be appreciated that the synthetic turf may comprise 100% of tufts formed from the yarn of the invention, but alternatively may comprise a combination of tufts formed from the yarn of the invention and tufts formed from other yarns such as, conventional monofilament, texturised monofilament, and fϊbrillated tapes.

Figure 4 shows an individual resulting tuft. The individual monofilaments of the upper part of each cut end of the yarn in the tuft are separated from each other, as indicated at Ia, while in the central part of the yarn tuft penetrating through the backing material 2 and at the rear of the backing material, the monofilaments, as indicated at Ib, remain fixed together by unbroken part(s) of the connecting links 5 between adjacent filaments. This overcomes the problem referred to previously in relation to Figure 1, where the upper or inner monofilaments may be pulled from the turf in use because the

coating material 3 is not always effective to retain these monofilaments. In the turf of the invention the same upper or inner monofilaments if not contacted by the coating 3, will in at least many cases remain linked to other monofilaments of the turf which are, at the centre section of each tuft, and these other, outer monofilaments are fixed to the backing material by the coating 3. Thus an integral structure is formed in which it is more difficult for individual monofilaments to be pulled from the tuft in normal use of the turf.

Figure 5 schematically illustrates mechanical processing to break the individual monofilaments 1 of the tufts from one another. In Figure 5 those tufts in which this has occurred are indicated at 7, while individual tufts that have not (yet) been mechanically processed are indicated at 8. The backing material is indicated at 2 as before. A "brush" 9 passes over the individual tufts after tufting into the backing material and cutting, to beat the exposed upper ends of die individual tufts. In Figure 5 brush 9 is represented as a rotating tool which extends transversely across the turf and which has spikes or other protrusions extending from its periphery and along its length or has an otherwise non- smooth peripheral surface, which will beat and split the yarn monofilaments from one another as at Ia in Figure 4. In the embodiment shown, the rotating brush 9 is fixed and the turf is arranged to move in the direction of arrow A but in an alternative embodiment the brush 9 or equivalent may move relative to the turf. For example, such a brush maybe added to a conventional turf manufacturing line (where the spinneret has also been changed to one required to form the yarn of the invention), to impact and beat the turf after stitching and cutting and before the finished turf is rolled up for storage and/or delivery to an installation site where the turf is to be used.

Alternatively, the brushing may be carried out on site, at for example a sports field installation where the turf is installed, and after laying of the turf. A motorised machine having a rotating brush comprising stiff bristles for example, may be run over the turf one or more times, in one or more directions, to beat the tuft ends of the turf, to separate the monofilaments in the same way. In this specification "brush" is intended to indicate such a brush with stiff bristles, a rotating tool with protrusions from it's outer periphery as shown schematically in Figure 5, or any other mechanical device which can be passed over the turf or the turf moved relative thereto, and which is then effective to break the links between the individual monofilaments of the turf exposed above the backing material 2.

With reference to Figure 4, the brush may be effective to break apart the individual monofilaments over substantially all or most, or alternatively a minor part or portion, of the pile height, as indicated by H, of the turf. For example, in one form the brush may be arranged to break the frangible webs connecting the individual monofilaments over a substantial portion, as indicated by B, of the pile height of the tufts from their free ends toward the backing material such that the frangible webs extend from underneath die backing material to above the backing material for a minimal or minor portion of the pile height. In an alternative form, the brush may be arranged to break the frangible webs connecting the individual monofilaments of the tufts over a minor portion of the pile height of the tufts toward their free ends such that the frangible webs remain intact from behind the backing material to above the backing material for a major portion of the pile height. It will also be appreciated that the brush may be arranged to break the frangible webs between the individual monofilaments for any desired portion of the pile height of the tufts, such that the ratio of B to H can be selected. In synthetic turf of the invention typically the height or length of the pile from the upper side of the backing material to the ends of the monofilaments is in the range 1 to 5 inches. Typically the turf is of a gauge (spacing between adjacent rows) in the range 2/16 to 1 Vz inches, and more typically 3/16 to ³ A inches. After installation the turf may optionally be filled with a granular infill material, to a part height for example about 2/3 of the pile height of the turf, of for example sand or a mixture of sand and granules of a resiliendy compressible material such as natural or synthetic rubber.

The foregoing description of the invention includes preferred forms thereof. Modifications may be made thereto without departing from the scope of the invention as defined by the accompanying claims.