Sports surfaces, their uses and their manufacture

Abstract

The sports surface (10) comprises a backing layer (1) and a pile layer (2), the pile layer comprising pile fibres connected to the backing layer to form loops (21), the loops being closely packed to form a substantially continuous playing surface, which can be used for ball games or other recreational purposes. The present application further relates to a method for making such a sports surface.

Description

[Technical field]

[0001] The present invention relates to a textile-based sports surface and a method for producing the textile-based sports surface. The sports surface comprises a backing layer and a pile layer and is suitable for a variety of sports and recreational activities, including field hockey, lawn bowls, cricket, golf, tennis and paddle. The sports surface exhibits excellent performance without watering and is therefore particularly suitable for use in its dry state, i.e. without the addition of water. [Background technology]

[0002] Sports surfaces must meet certain performance criteria to allow comfortable play and / or comply with standards and regulations set by professional sports associations. For example, regulations may be established to guarantee minimum or maximum ball rolling distance, specify ball rebound characteristics, or allow safe player sliding performance. Natural grass is one of the preferred surfaces for many sports, but is often found to be too costly to maintain for daily use. For this reason, artificial grass has become increasingly popular and has been developed through multiple generations to achieve sports performance equal to or even exceeding the natural version. In general, artificial grass comprises a backing layer and a pile layer, which are connected by tufting or weaving, or the like. The pile layer forms the playing surface.

[0003] The pile layer of a sports surface determines the performance of the sports surface. Infill materials may also be provided to achieve the required resilience and other sports performance properties. Features such as pile height, yarn type, fiber density, and stiffness all play a role in the behavior of the ball on the playing surface. For example, if the friction between the ball and the playing surface is too high, the ball may not roll the required distance. In general, pile development has attempted to mimic its natural equivalent by providing different fiber shapes and materials. WO 2006 / 091067 A1 shows an example of an artificial turf system specifically intended for use as a playing field, and in particular for soccer.

[0004] Textile-based sports surfaces are widely used to play ball games such as soccer and hockey, but a drawback is that the friction of the playing surface can be too high. This can have a negative impact on sports performance and can lead to injuries to players when slipping. To mitigate these negative effects, the sports surfaces can be wetted to reduce the friction on the playing surface. This has been applied in particular in hockey arenas, and this solution is commonly called "water-based fields".

[0005] Although the water-based fields described provide superior sports performance, the large amounts of water required to wet the field are not always readily available. Furthermore, using large amounts of water, especially during periods of draft, is not environmentally friendly. Preparing a water-based field for a match can require as much as 20,000 liters of water per session of play. Although such water-based fields have become the standard for sports such as hockey, their use is falling out of favor as they put the sport out of reach of some groups of players and countries where water is scarce. Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention seeks to further improve such sports surfaces by providing a field with a comparable or improved level of performance while reducing the amount of water needed to wet the field and / or eliminating the use of water entirely. [Means for solving the problem]

[0007] Thus, according to a first aspect of the invention, there is provided a sports surface comprising a backing layer and a pile layer, the pile layer comprising pile fibres connected to the backing layer to form loops, the loops being closely packed to form a substantially continuous playing surface. The pile fibres may be formed by monofilaments, fibrillated tapes, slit tapes or the like. Preferably, the pile fibres are formed by monofilaments, i.e. fibres extruded as individual filaments.

[0008] Here, the term "sports surface" is used to denote a dedicated surface for conducting sports or other recreational activities, for example a dedicated surface for playing field hockey, lawn bowls, cricket, golf, tennis, paddle or football. It will be understood that in an embodiment the sports surface can be tailored to comply with standards set by professional sports associations with regard to some performance characteristics such as ball rolling distance or ball rebound height. The sports surface according to the present claims represents a significant departure from conventional thinking in that it no longer seeks to approximate natural grass, but instead provides sports performances that are fundamentally different from natural grass and existing artificial grasses.

[0009] The pile layer comprises a plurality of loops, and the playing surface is formed by the tops of the plurality of loops. The term "loop top" is used to describe the top and the outside of the plurality of loops that form the playing surface. Typically, each loop has a loop bottom defined at the point where the pile fibers extend from the top surface of the backing layer. From the loop bottom, two loop sides extend between the backing layer and the playing surface. The playing surface is formed by the loop tops that connect the two loop sides. It will be understood that the loops are formed by continuous fibers, and the definition of what is the loop side and loop top may depend on the instantaneous shape of the loop. The loop shape depends, for example, on the pressure currently and / or previously applied to the playing surface, but may also depend on other factors, such as the degree of packing of adjacent loops.

[0010] Conventional sports surfaces usually use cut fibers in the pile layer. Compared to such conventional cut fiber playing surfaces, the resistance of the playing surface is reduced. The loops provide better support for the same pile fiber volume, and as a result, the ball does not sink as far into the field. This results in a smaller contact area between the pile fibers and the ball, which reduces friction between the ball or the player's skin on the one hand and the playing surface on the other. Due to the smaller friction, the ball decelerates less and there is a smaller risk of skin abrasions when a player makes a sliding tackle. If a player slips or slides on a playing surface with high friction resistance, there may be localized high temperatures that can lead to friction burns and skin abrasions.

[0011] In addition to the smaller contact area, the contact area of ​​the playing surface according to the invention also has a lower roughness. Cut fibre playing surfaces may have sharp edges around the cut surface of the pile fibres, whereas the sides of the top loops forming the playing field are usually very smooth. This additional smoothness contributes to a further reduction in friction between the ball or the player's skin on the one hand and the playing surface on the other hand.

[0012] As a result of the lower friction, it is usually not necessary to provide additional water on the sports surface to further reduce friction. From an environmental point of view, this is a major advantage. Conventional water-based fields used for field hockey, for example, require approximately 20,000 liters of water per hour of play for a single hockey field.

[0013] The loops provide a significant amount of support and because they are able to deform the resilience of the layer is improved, which increases player comfort compared to cut pile fabrics and results in a lower ball bounce as more energy is absorbed in the pile layer.

[0014] The loops further increase the rotational resistance of the playing surface and improve grip on the ball and the players' feet, which helps prevent players from accidentally slipping and falling or being injured.

[0015] The increased lifespan of the surface is further advantageous for the sports surface according to the invention. Due to the relatively good flexibility of the loops, wear of the pile fibres is reduced. Furthermore, the pull-out of the pile fibres is reduced, since the pull-out of the loops requires more force than a single cut pile fibre. Furthermore, the closed loops make it more difficult to split them and damage the pile fibres, since there are no pile fibre ends extending to the surface where they can be damaged. This in turn allows the fibre material to be adapted, since split resistance is no longer of utmost importance. It is therefore easier to tailor the fibre material to improve comfort or reduce friction, for example by using softer materials or coatings.

[0016] Finally, in most professional sports, surface consistency is paramount to the game. The loops are closely packed to form a virtually continuous playing surface. By packing tightly, the consistency of the field improves. Consistency remains assured over a longer period for good longevity of the field.

[0017] The tight packing of the loops can help provide the necessary support and resilience of the sports surface. In one embodiment, the pile layer has a density of at least 100 g / m2 per mm. 2 , preferably at least 150 g / m per mm 2 Here, the pile density ratio is defined as the mass of the pile layer (g / m2) per unit of pile layer height (mm). The mass of the pile layer may be determined according to ISO 8543, and the pile height may be measured according to ISO 2549. Thus, the units of pile density ratio are grams per square meter per millimeter.

[0018] Alternatively, dense loop packing can be defined by the number of loops per square meter, or the number of loops or filaments per square meter. In an embodiment, at least 40,000 loop bundles per square meter, preferably at least 60,000 loop bundles per square meter, are provided. The number of loop bundles may be measured according to standard ISO 1763.

[0019] In one embodiment, at least 400,000 individual loops per square meter are provided, preferably at least 600,000 loops per square meter, where each loop is formed by an individual filament or fiber. Thus, a count of 600,000 loops corresponds to 1,200,000 filaments in the cut fiber pile layer. The number of filaments may be measured according to standard ISO 1763.

[0020] In one embodiment, the pile layer has a pile height of 5 mm to 20 mm, preferably 8 mm to 10 mm. The pile height may be measured according to ISO 2549. For larger pile heights, the sports surface is more susceptible to damage, since the chances that a part of the player's shoe will be caught in the loops increases. Thus, the larger the loops, the greater the risk of being pulled out.

[0021] In some embodiments, the loops have an aspect ratio (H / W) of less than 3. The loop base is generally determined by the way the loops are formed. For tufted pile layers, the loop base will be determined primarily by the tufting needle size and bundle diameter. When unconstrained, the loops tend to have a curvature, i.e., moment of area 2, determined by the structural properties of the fibers. When the loops are closely packed, adjacent loops may support each other, resulting in a narrower loop. Generally, the maximum loop width is obtained within the pile layer at a position away from the top surface of the backing layer. However, it is not excluded that other structures may form loops with a larger width at their base where the pile exits the backing layer.

[0022] In some embodiments, the aspect ratio may be at least 2.2, preferably at least 2.4. For tufted pile layers, the loop bottom is provided by a single opening in the backing layer. In embodiments, the loop bottom may be wider.

[0023] In one embodiment, the pile layer has a mass of at least 800 g / m2. Mass may be determined according to standard ISO 8543.

[0024] In one embodiment, the backing layer has an upper surface and a lower surface, the pile fibers extend through the backing layer and along the lower surface of the backing layer, and the pile fibers at the lower surface of the backing layer have been heated to weaken or break the material. It will be understood that the pile fibers are generally pulled down during extrusion to accommodate the polymeric material. Heating the material to a softening temperature can cause it to lose directionality and reduce fiber strength. When a large pulling force is applied to one of the loops of the pile layer, the loop may be pulled out, breaking the weakened lower thread of the backing. As a result, the effects of run, i.e., loss of consecutive loops from the same column or row when one loop is pulled out, and fraying, i.e., loss and damage of pile fibers from cut edges, may be reduced or prevented entirely.

[0025] While attempts have been made in the past to use loop pile structures for sports surfaces, these are believed to have failed due to the tendency of the loops to snag and cause unacceptable runs. Cutting the loops to provide a cut pile sports surface was seen as the only solution to this problem. In certain embodiments, the present disclosure teaches how to overcome the run problem by providing weak points in the pile fibers that avoid runs.

[0026] In some embodiments, the pile fibers on the underside of the backing layer are at least partially melted. The pile fibers may be partially melted or may be completely fused. The term "fused" is used to describe the situation where two components or fibers are completely melted, i.e., to form a unitary component. The melting may simply cause one component to mold around the other without actual bonding or fusion occurring. In this case, upon cooling, there may simply be a mechanical bond of the two components, e.g., the pile fibers and the woven backing layer. Melting the pile fibers together can result in a bundle of fibers on the underside of the backing layer that has a higher pull strength. A fused bundle of filaments is more difficult to pull out than a single filament, but it can still run, although not easily.

[0027] In some embodiments, the sports surface further comprises a locking layer disposed on the underside of the backing layer to lock the pile fibers to the backing layer and / or to mitigate runs. The locking layer prevents pull-out of the pile fibers from the backing layer and can further reduce the effects of runs due to its enhanced pull-out strength.

[0028] In some embodiments, the locking layer comprises one of a hot melt adhesive, a powder melt adhesive, a coating layer, or a laminating film. The coating layer may be, for example, a latex or polyurethane coating. In embodiments, a combination may be applied. For example, both a powder melt adhesive and a laminating film may be applied.

[0029] Additional layers may be provided under the backing layer for locking and other purposes. Woven or sewn felt layers may be provided to add strength and durability or to enhance shock absorption. Thus, sports surfaces may be manufactured with integral shock pads.

[0030] In some embodiments, the pile layer further comprises a plurality of cut loops. Such cut loops preferably have a pile height similar to or less than the loops, whereby the playing surface is at least partially formed by the looped pile fibers. In embodiments, all loops are uncut. A combination of cut and uncut loops can be used to optimize the sports performance characteristics of the playing field. Additionally, cut loops can be provided to reduce the effects of "wear" and "runs", since cutting loops reduces the length of the continuous loops such that fewer loops are pulled out. Alternatively, the effects of runs and wear may be reduced by cutting pile fibers at the underside of the backing layer.

[0031] In one embodiment, at least 70% by weight of the pile layer is comprised of uncut loops, and preferably at least 90% by weight of the pile layer is comprised of uncut loops. The term "uncut" loops in this context is understood to refer to loops in the pile layer, i.e., above the top surface of the backing layer, that have not been cut.

[0032] In one embodiment, the pile fibers comprise a polymeric material, preferably a polyethylene material. The polymeric material may be extruded and oriented by squeezing. Polyethylene, particularly low density polyethylene, is the preferred material due to its good elasticity and therefore best suited to achieve the required sports performance. Alternatively, for example, polypropylene or polyamide materials may be used to form the pile layer. As mentioned above, due to the use of loops and the lack of cut ends that may be prone to wear and tear, softer materials may be used than are traditionally used in artificial turf.

[0033] In an embodiment, the pile fibers forming the loops are arranged in bundles. Preferably, each bundle comprises 3-30, preferably 6-12, bundles of monofilaments, fibrillated tapes, or slit tapes. The application of piles in bundles is efficient from a manufacturing point of view, and a person skilled in the art will appreciate the trade-off between bundle size and processability. In an embodiment, the pile fiber bundles have a linear density of 2000 dtex to 20000 dtex, preferably 6000 dtex to 10000 dtex.

[0034] According to one embodiment of the invention, the fibers in the bundle have a linear density of 500 dtex to 2000 dtex, preferably 800 dtex to 1200 dtex, it being understood that this does not correspond to, for example, indoor carpeting materials, which may also be formed with loop pile, but have values ​​much lower than 100 dtex.

[0035] In some embodiments, the pile layer further comprises a texturized yarn. The texturized yarn may be formed as a looped pile fiber or may be a cut pile fiber. The texturized yarn may have the same pile height or may be shorter and arranged to form a resilient thatch layer.

[0036] In some embodiments, the pile fibers are tufted into the backing layer. Those skilled in the art will be familiar with procedures for tufting such loops. The tufts may be straight or may be arranged in a zigzag fashion. A slight zigzag has been found to be useful in avoiding an overly straight pattern of loops that may introduce directionality into the playing surface. Alternatively, the pile fibers may be integrated into the backing layer in a different manner, for example, by knitting, weaving, or needling.

[0037] In an embodiment, the loop has a pull-out strength of at least 35N, preferably at least 50N. The pull-out strength may be determined by the minimum pull-out force defined by ISO standard 4919 for the loop. If the loop comprises multiple fibers in a bundle, this is the pull-out strength of the bundle. Such strength is usually required by sports associations as a minimum. The playing field according to the invention can be constructed to comply with the standards set by the sports associations.

[0038] In one embodiment, the pile fibers have a cross-section with an aspect ratio (w / t) of 5 or less, preferably 4 or less. Those skilled in the art will appreciate that this is relatively thick for a conventional artificial grass blade. However, in this case, the fibers are no longer functioning as upright blades, but are intended to mimic grass. Instead, the shape provides the pile fibers with structural strength in the form of a bowed arch.

[0039] In certain embodiments, the pile fibers may have a generally circular, elliptical, oval, lenticular, diamond, or rectangular cross-sectional shape.

[0040] In another embodiment, the pile fibers may have a plurality of elongated ribs extending along the elongated direction of the pile fibers. A disadvantage of a smooth circumferential surface of the pile fibers is that it can be dazzling when the light is bright. Roughening the surface of the pile fibers by providing elongated ribs along the pile fibers can reduce glare and provide a more natural appearance.

[0041] In certain embodiments, the sports surface is suitable for ball games, in particular field hockey, lawn bowls, cricket, golf, tennis or paddle. It will be understood that the pile layer may be tailored to comply with the standards and requirements for a particular sports application. Furthermore, it will be understood that the sports surface may also be used for other recreational activities without a ball.

[0042] In certain embodiments, the sports surface is suitable for use without wetting the surface. As explained above, conventional fields are often used in combination with water to enhance sports performance. Water reduces the resistance of the playing surface, thereby improving sports performance. It has surprisingly been found that for the sports surface according to the invention, water is not required for good sports performance, since the resistance is inherently lower.

[0043] In an embodiment, the backing layer comprises a polymeric material. For example, the backing layer may be made of polypropylene, which exhibits excellent stability to outdoor conditions, exhibits high creep resistance, and has excellent longevity. The stability of the backing layer is important since the temperature on the pitch can vary from below freezing up to 85 degrees Celsius if exposed directly to the sun without suitable cooling facilities. Sufficient creep resistance is particularly important for sports surfaces applied to playing fields that have even a slight slope for drainage, otherwise static forces may result in deformation of the sports surface over time. Alternatively, the backing layer may be made of another polymeric material, such as polyethylene, and preferably high density polyethylene. High density polyethylene materials may also be used to manufacture the backing, which exhibits excellent stability to outdoor conditions, exhibits high creep resistance, and has excellent longevity. Furthermore, providing both the backing layer and the pile fibers of polyethylene materials enhances the ability to recycle the product at the end of its life.

[0044] Preferably, the backing layer is made of a polymeric material having a higher melting temperature than the pile fibers. In an embodiment, the backing layer comprises a polymeric material having a first melting temperature and the pile fibers comprise a polymeric material having a second melting temperature, the difference between the first and second melting temperatures being at least 2 degrees Celsius, preferably at least 3 degrees Celsius, and may be greater than 5 degrees Celsius. The difference in melting temperatures allows the pile fibers to be fixed in the backing layer through melting of the pile fibers without affecting the filaments of the backing layer.

[0045] In one embodiment, the sports surface is heat-stabilized. For heat stabilization, the sports surface is heated above the highest temperature that can be expected during play. Heat stabilization can improve the dimensional stability of the sports surface. The backing layer may be a woven fabric, and heat stabilization relaxes the strains induced in the filaments of the backing layer during the weaving process. It will be understood that weaving is generally performed at an ambient temperature where the filaments have a given elastic modulus. The weaving action creates bends and twists in the filaments that remain when the process is completed. When the temperature of the backing layer is increased, the induced strains can be restored by relaxation of the bends and relaxation of the filaments. A side effect of heat stabilization can be a reduction in the height of the pile layer of about 20%.

[0046] Heat stabilization may be performed using a variety of different methods. In one embodiment, heat stabilization is performed by passing the substrate along a body having a heated surface, and the first side of the backing layer is placed in contact with the heated surface. The heated surface may be a roller or a calender as is commonly known in the art. In another embodiment, heat stabilization is performed by directing the backing layer through an oven without direct contact with a heated surface. For example, a tenter frame may be used to direct the backing layer through the oven.

[0047] According to a second aspect of the present invention and in accordance with the advantages and benefits described herein above, there is disclosed a use of a sports surface according to the present invention for ball games, preferably for field hockey, lawn bowls, cricket, golf, tennis or paddle.

[0048] In some embodiments, the sports surface is used without deliberately wetting the surface prior to improving play, where "deliberately wetting the surface prior to improving play" refers to the common practice of wetting hockey fields to enhance performance. It will be appreciated that water may be naturally added to outdoor fields when it is raining, or in some cases when the field is cleaned, or for cooling purposes. A sports surface according to the present invention may be used without wetting and still meet the desired performance criteria.

[0049] According to a further aspect of the present invention and in accordance with the advantages and benefits herein above, there is provided a method of manufacturing a sports surface, the method comprising providing a backing layer, the backing layer having an upper surface and a lower surface, incorporating a plurality of pile fibres into the backing layer so as to stand up as loops from the upper surface, the loops being connected to each other at the lower surface of the backing layer, and closely packing the loops to form a substantially continuous playing surface.

[0050] In some embodiments, the method further includes weakening the pile fibers on the lower surface of the backing layer to prevent runs.

[0051] In some embodiments, the method further includes at least partially melting the pile fibers at the lower surface of the backing layer to inhibit or reduce the molecular orientation of the fibrous material to prevent runs and / or prevent fiber pull-out.

[0052] In some embodiments, the method further comprises heat stabilizing the sports surface.

[0053] Embodiments will now be described, by way of example only, with reference to the accompanying schematic drawings in which corresponding reference symbols indicate corresponding parts. In the drawings, like numerals indicate like elements. Multiple instances of an element may each include a different letter appended to the reference number. For example, two instances of a particular element "20" may be referred to as "20a" and "20b." A reference number may be used without a suffix (e.g., "20") to generally refer to unspecified or all instances of that element, while a reference number may include a suffix (e.g., "20a") to refer to a particular instance of an element. [Brief description of the drawings]

[0054] [Figure 1A] 1 shows a schematic cross-sectional side view of a sports surface according to a first embodiment; [Figure 1B] FIG. 1B shows a detail of looped pile fibers in a sports surface according to FIG. 1A. [Diagram 2] 1 shows a cross-sectional view of a filament in a pile fabric according to a first embodiment. [Diagram 3] 1 shows a first embodiment of a device that can be used to heat stabilise a sports surface and / or provide an anti-run treatment to pile fibres. [Figure 4A] FIG. 1 illustrates a schematic cross-sectional side view of a hockey ball positioned on a sporting surface according to an embodiment of the present invention. [Figure 4B] 1A and 1B are schematic diagrams illustrating a cross-sectional side view of a hockey ball placed on a prior art water field with cut pile fibers. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0055] The figures are intended for illustrative purposes only and do not limit the scope or protection of the claimed invention.

[0056] Following are descriptions of specific embodiments of the invention, illustrated by way of example only and with reference to the drawings.

[0057] 1A shows diagrammatically a cross-sectional side view of a first embodiment of a sports surface 10 comprising a backing layer 1 having a bottom surface 11 and a top surface 12, a pile layer 2 with loop bundles 20, a locking layer 3, and a playing surface 15. The loop bundles 20 are formed by bundles of pile fibres 27 formed as monofilaments. Each monofilament forms individual loops 21 having a loop side 22, a loop top 23 and a loop bottom 24.

[0058] The backing layer 1 is a woven fabric having longitudinal and transverse tapes tufted with loops 21. The backing layer 1 is made from polypropylene and has a weight of about 250 g / m 2 The backing layer 1 has a fabric weight of about 1000 g / m². The backing layer 1 comprises two sub-layers 13 and 14 that are sewn together to form the main backing layer 1. Nevertheless, it will be appreciated that a single layer backing layer, or a backing layer made from another material, may also be used in other embodiments. The polypropylene backing layer 1 has a melting point of about 160 degrees Celsius.

[0059] The pile layer 2 comprises a plurality of closely packed loop bundles 20, each formed by ten loops 21 extending from the top surface 12 of the backing layer 1 to the playing surface 15. Each loop 21 has two loop sides 22a, 22b and a loop top 23, which are connected to each other by the loop top 23. The loop tops 23 of all the loops 21 together form the playing surface 15 of the sports surface 10. The playing surface 15 can support a ball or a player during play.

[0060] At the lower surface 11 of the backing layer 1, the fibers 27 are continuous between successive loop bundles 20. The portions of the fibers 27 extending along the lower surface 11 of the backing layer 1 are locked to the backing layer 1 by the locking layer 3. The locking layer 3 has a tensile strength of about 1000 g / m 2 The coating comprises a latex coating having a weight of

[0061] 1B shows detail of a single loop 21 in loop bundle 20. Each loop side 22 extends from the top surface 11 of backing layer 1 approximately the pile height H, where loop bottom 24 is defined as the point where loop 21 intersects with top surface 12 of backing layer 1. Loop 21 is widest approximately ⅔ the pile height from loop bottom 24. Loop 21 has an aspect ratio (H / W) of approximately 2.5. EXAMPLES

[0062] Pile layer - Example 1 According to a first embodiment of the pile layer 2, the loops 21 have a height of about 8 mm, measured as the distance between the top surface 11 of the pile layer 2 and the average height of the loop tops 23. The loops 21 are provided at a line rate of about 375 lines per metre over the length of the sports surface 10 and a gauge of about 4 mm along the width of the sports surface. In this way, about 100,000 bundles of loops are provided per square metre of the sports surface 10.

[0063] Each bundle has a linear density of 8000 dtex and consists of 10 monofilaments of 800 dtex each. As a result, the sports surface 10 comprises about 2 million filaments per square meter, with each loop side 22 counting as an individual filament. The loops 21 are thus packed closely together to form the playing surface 15. The pile layer 2 has a linear density of about 2000 g / m 2 has a total pile mass of

[0064] The pile height is approximately 8mm, with 250g / m per mm of height. 2 The pile density ratio is about 1.5. The aspect ratio (H / W) is about 2.5.

[0065] Pile layer - Examples 2 to 5 Table 1 shows the properties of four further examples of pile layer 2. The features of pile layer 2 already described above with respect to the first example may also be present in examples 2-5 and will not be discussed in full again here. For example, the loop shape and loop aspect ratio (H / W) are approximately the same as in example 1.

[0066] [Table 1]

[0067] Pile layer - Example 6 According to a second embodiment of the pile layer 2, the loops 21 have a height of 9 mm. The loops 21 are provided with a stitch rate of about 450 lines per metre over the length of the sports surface and a gauge of about 4 mm along the width of the sports surface. In this way, about 115,000 bundle loops are provided per square metre of the sports surface 10.

[0068] The bundles are formed by two different types of filaments. Each bundle has a linear density of 8000 dtex and comprises 4 fibres of first straight filaments of 1000 dtex and 5 fibres of textured filaments of 800 dtex. The pile layer 2 has a linear density of about 2400 g / m 2 with a total pile mass of approximately 260g / m per mm height 2 The pile density ratio is

[0069] Pile fiber filament material The pile fibers of each of Examples 1-6 are made from a polyethylene (PE) material, which can provide desirable sports performance. The filaments may further comprise one or more additives, preferably selected from the group including antioxidants, UV stabilizers, pigments, processing aids, acid scavengers, lubricants, antistatic agents, fillers, nucleating agents, and clarifiers.

[0070] In each of the examples, approximately 90.5% by weight of the filament is made from PE, with the remaining 9.5% by weight being provided by additives, e.g., 6% by weight pigment, 3% by weight calcium carbonate, and 0.5% by weight processing aid, however, it will be understood that different compositions may be used in other embodiments.

[0071] According to a first embodiment of the PE composition used in pile layer examples 2 and 4, the filaments of the pile fibers are made from a low density polyethylene material formed from monomers having four carbon atoms, i.e., a butene-based PE, referred to herein as C4 grade PE. C4 grade PE has a melt flow index (MFI) of about 2 and a melt flow rate of 918 kg / m 3 The straight pile fibers of Example 6 are also C4 grade PE.

[0072] According to a second embodiment of the PE composition used in pile layer examples 3 and 5, the filaments of the pile fibers are made from a low density polyethylene material formed from monomers having six carbon atoms, i.e., a hexene-based PE, referred to herein as C6 grade PE. C6 grade PE has higher toughness and flexibility than C4 grade PE. C6 grade PE has a melt flow index (MFI) of about 3.5 and a melt flow rate of 918 kg / m 3 The textured filaments of Example 6 are also of this polymer grade.

[0073] According to a third embodiment of the PE composition used in Example 1, the filaments of the pile fibers are made from a mixture of C4 and C6 grade PE, about 85% by weight of the PE mixture being made of C4 grade PE and 15% by weight of the PE mixture being made of C6 grade PE.

[0074] Usually in conventional sports surfaces with cut pile fibres, higher grades of PE are used to increase toughness. If the material is soft, e.g. C4 grade PE, the pile fibres tend to be damaged, mainly due to the blades splitting off from their top surface. By providing closed loops in the pile layer of the sports surface according to the invention, splitting of the pile fibres is prevented and the softer C4 grade PE can be used without adverse consequences. A higher proportion of C4 grade PE in the fibre material results in an even softer fibre which is more comfortable for the player when in use.

[0075] Filament cross-sectional shape The filaments may be provided in many different shapes, such as generally circular, oval, lenticular, diamond shaped, rectangular, or shaped as a capital letter "C" or "D." Because no separate lobed ends are provided, the closed loops protect the pile fibers from splitting, and therefore the cross-sectional shape is less likely to be a particular shape to prevent splitting of the pile fibers.

[0076] Figure 2 shows the cross-sectional shape of the fibres 27 used in the pile layer 2 according to Example 1. The cross-section has a lens shape with a maximum width w of about 0.75 mm and a maximum thickness t of about 200 μm. Thus, the aspect ratio (w / t) is about 3.75. The thicker filaments forming the loops provide a good ratio of contact area to cross-sectional area of ​​the pile fibres, ensuring that the loops are structurally more resilient due to the higher moment of area of ​​the fibres.

[0077] The surface of the fabric 27 is relatively smooth, which reduces friction at the contact area, which has several beneficial effects, in particular reducing the risk of skin abrasions when an athlete falls or slides along the playing surface 15.

[0078] The surface of the fiber 27 is provided with a plurality of elongated ribs 25 extending along the elongated direction of the fiber 27. The ribs 25 along the surface reduce glare from the surface in bright areas. It will be appreciated that if glare reduction is not required, for example for indoor use, the ribs 25 may be omitted. Examples 2-6 have filaments or fibers with a similar lens shape, but do not include the ribs 25.

[0079] Heat stabilization and heat treatment The sports surfaces 10 according to each of Examples 1-6 are heat stabilized prior to use by directing the sports surface 10 through an oven using a tenter frame during application of the latex coating. This process for drying the latex material is well known to those skilled in the art and also results in a reduction in pile height from the initial tufted state.

[0080] In addition to the heat stabilisation of the entire sports surface, the fibres 27 on the lower surface 11 of the backing layer 1 may be subjected to an additional heat treatment step to prevent runs.

[0081] FIG. 3 shows an exemplary embodiment of an apparatus 30 that can be used to perform the heat treatment. The sports surface 10 is provided to a feed roller 31 and guided through the apparatus 30 using a number of guide rollers 32. The sports surface 10 is conveyed through the machine at a speed of 1-30 m / min and guided along the heated surface 35 of the roller 34. In the case of the polypropylene backing layer described with reference to Example 1, the melting temperature of the PP backing layer 1 is at least 25C above the temperature at which the pile fibers 27 soften. By heating the pile fibers 27 of the lower surface 11 of the backing layer 1 to a point where they melt, the fibers 27 are weakened at this point and, when subjected to sufficient force, will break before running. To weaken the pile fibers 27, it may be sufficient that the breaking strength of the fibers is less than the pull-out force of the individual fibers.

[0082] The heat treatment may be combined with heat stabilization or may be performed separately. The heat treatment may further be combined with the application of a locking layer. For example, hot melt adhesive or powder melt may be added to further increase the pull-out strength. A device 33, for example a watering device, may be arranged within the equipment 30. The device 33 may sprinkle hot melt adhesive powder on the lower surface 11 of the backing layer 1 before the sports surface 10 is conveyed along a heated roller 34.

[0083] Sports Performance The sports surface 10 has enhanced sports performance characteristics compared to a prior art sports surface 80 used on a water-based field. Figure 4A shows generally a hockey ball 7 positioned on top of the playing surface 15 of the sports surface 10 according to the invention, and Figure 4B shows generally a hockey ball 7 positioned on top of the playing surface 15 of the prior art sports surface 80. It will be understood by those skilled in the art that the drawings are highly schematic and that in reality a hockey ball is much larger than a few loops or cut pile fibres.

[0084] On each of the sports surfaces 10, 80, frictional resistance occurs between the ball 7 and the surface when rolling and when skidding. Both movements are related to each other, and the transition from skidding to rolling is a fundamental feature in many games. "Rolling resistance" is significantly less than the resistance to skidding, but depending on the speed and rotation imparted to the ball, the transition between the two can be different. In this context, skidding is used to describe the movement of the ball moving along the surface without rotation. Counter-rotation may also be present.

[0085] Rolling resistance is defined as the force acting at the point of contact between a ball and a surface whose direction is opposite to the direction of movement, thus causing the ball to decelerate as it moves across the surface. Friction between the ball and the surface causes changes in speed, direction, and rate of rotation. The type of surface can dramatically affect friction. Differences in pile height, yarn type, fiber density, and stiffness (among others) all play a role in the behavior of the ball. If the friction between the ball and the surface is too high, the ball will not roll the required distance.

[0086] The ball continues to skid across the surface until its linear velocity parallel to the playing surface 15 decreases and the angular velocity of the ball 7 increases to the point where rolling occurs. For a smooth roll there cannot be any skidding between the ball and the surface and therefore a balance between the forward and rotational speeds at the point of contact with the surface is required for pure rolling. The transition between rolling friction (RF) and skidding friction (SF) is influenced by various variables of the sports surface 15, in particular by the pile layer 2.

[0087] It is an advantage of the use of loops 21 in the pile layer 2 that it naturally has a lower skid friction than a conventional cut pile sports surface 80. The ball 7 is supported by the loop tops 23, which are formed by the sides of the filaments that form the loops 21. Thus, the contact area between the ball 7 and the playing surface 15 is relatively smooth.

[0088] In contrast, the cut pile fibers 81 of the pile layer of the prior art surface 80 have sharp edges and provide a non-smooth contact area. Furthermore, the hockey ball 7 does not sink as deeply into the pile layer 2 as the loops provide more support than cut pile fibers of the same pile fiber volume. As a result, the contact area of ​​the ball 7 with the pile fibers is reduced. Thus, the rolling and skid resistance provided by the playing surface 15 is significantly greater in the prior art system of the same pile fiber volume.

[0089] In prior art systems, for example for field hockey surfaces, water is added to reduce the friction of the playing surface, in particular the skid friction. By providing the loops 21, the skid friction is already inherently low and provides good sports performance even when no water is added. The ball rolling distance is approximately twice as large on the sports surface according to the invention compared to dry-feel sports surfaces currently used as water-based fields.

[0090] Table 2 provides an overview of the performance characteristics of the sports surfaces according to Examples 1-6 and compares them with a reference water-based sports surface with cut pile fibres. For the reference surface, the pile height is 13mm, provided with a line rate of 360 stitches per metre, a gauge of 210 per metre and approximately 75,000 tufts per surface. Each tuft comprises a bundle of 8000 dtex with 10 textured filaments of 800 dtex each.

[0091] [Table 2]

[0092] Besides the rolling and skid resistance, the ball rebound properties are important for the sports performance of the field. The loops 21 absorb more energy than cut pile fibres, which results in a lower ball rebound. It will be appreciated that depending on the sports application this may be preferred. For example, in field hockey, a lower ball rebound is advantageous. For a similar pile fibre volume, the ball rebound height is up to 15% lower for the dry sports surface according to the invention compared to prior art systems with cut pile fibres. It should be noted that the ball rebound values ​​are based on a solid concrete underside for comparison purposes only. In practical use the sports surface 10 will be installed on shock pads or provided with additional cushioning to achieve the required specifications.

[0093] Furthermore, the rolling resistance experienced by the ball 7 is important for sports performance: the rolling resistance has an effect on the grip and is approximately 5% greater on a dry sports surface according to the invention compared to a wetted prior art system with cut pile fibres.

[0094] Finally, in ball sports, surface consistency is paramount to the game. The playing surface 15 with loop tops 23 is very uniform due to the high density of loops. Furthermore, the consistency of the sports surface remains good over time because the pull-out strength is very good. Each of Examples 1-5 has a pull-out strength of at least 50N. Example 6 has a pull-out strength of about 45N.

[0095] Furthermore, as a result of the present loop-based system, additional fiber mass can be used without jeopardizing the fiber integrity of the system. In prior art cut pile systems, bundle size was limited by the ability to successfully secure all of the fibers in the bundle. A common failure mode was the loss of individual filaments weakening the strength of the bundle. Even if a few properly held fibers are pulled out of the center of the bundle, the remaining fibers become loose and soon are pulled out as well. With the loop-based system, even if a single fiber is partially pulled out, it is not removed and therefore does not affect the remaining fibers in the bundle.

[0096] Although the example sports surface 10 above has been designed for field hockey, those skilled in the art will appreciate that the field may also be adapted for use in a variety of different ball games, such as lawn bowls, cricket, golf, tennis or paddle, or for other recreational purposes.

[0097] The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not limiting. The scope of the invention is therefore indicated by the appended claims rather than by the foregoing description. It will be apparent to those skilled in the art that alternative and equivalent embodiments of the invention can be devised and put into practice. All changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope.

Claims

1. a backing layer and a pile layer and comprising, wherein the pile layer comprises pile fibers connected to the backing layer to form loops, and the loops are densely packed to form a substantially continuous playing surface, a sports surface.

2. wherein the pile layer has a pile density ratio of at least 100 g / m2 per mm, the sports surface according to claim 1.

3. at least 40,000 loops per square meter are provided, the sports surface according to claim 1.

4. wherein the pile layer has a pile height of 5 mm to 20 mm, the sports surface according to claim 1.

5. wherein the loops have an aspect ratio (H / W) of less than 3, the sports surface according to claim 1.

6. wherein the loops have an aspect ratio (H / W) of at least 2.2, the sports surface according to claim 1.

7. wherein the pile layer has a mass of at least 800 g / m ２ of, the sports surface according to claim 1.

8. wherein the pile fibers are arranged to prevent wire transmission, the sports surface according to claim 1.

9. wherein the backing layer has an upper surface and a lower surface, and the pile fibers penetrate the backing layer, the pile fibers on the lower surface of the backing layer are made fragile, the sports surface according to claim 1.

10. The sports surface according to claim 9, wherein the pile fibers on the lower surface of the backing layer are at least partially melted.

11. Further comprising a locking layer provided on the lower surface of the backing layer for locking the pile fibers to the backing layer and / or for reducing transmission lines. The sports surface according to claim 1.

12. The locking layer comprises one of a hot melt adhesive, a powder melt adhesive, a coating layer, or a laminated film. The sports surface according to claim 11.

13. The pile layer further comprises a plurality of cut loops. The sports surface according to claim 1.

14. At least 70% by weight of the pile layer is composed of uncut loops. The sports surface according to claim 1.

15. The pile fibers are made of a polymer material. The sports surface according to claim 1.

16. The pile fibers are arranged in bundles. The sports surface according to claim 1.

17. Each bundle has a linear density of 2000 dtex to 20000 dtex. The sports surface according to claim 16.

18. The pile fibers have a linear density of 500 dtex to 2000 dtex. The sports surface according to claim 1.

19. The pile layer further comprises a texturized yarn. The sports surface according to claim 1.

20. The pile fibers are tufted into the backing layer. The sports surface according to claim 1.

21. The loops have a pull-out strength of at least 35 N. The sports surface according to claim 1.

22. The pile fibers have a cross-section with an aspect ratio (w / t) of 5 or less. The sports surface according to claim 1.

23. The pile fibers have a width of 50 to 450 μm. The sports surface according to claim 1.

24. The pile fibers have a cross-sectional shape that is substantially circular, elliptical, oval, lens-shaped, diamond, or rectangular. The sports surface according to claim 1.

25. The pile fibers have a plurality of elongated ribs extending along the elongated direction of the pile fibers. The sports surface according to claim 1.

26. The sports surface is suitable for ball games, particularly field hockey, lawn bowls, cricket, golf, tennis, or paddle. The sports surface according to claim 1.

27. The sports surface is suitable for use without wetting the surface. The sports surface according to claim 1.

28. The backing layer is made of a polymer material. The sports surface according to claim 1.

29. The sports surface is thermally stabilized. The sports surface according to claim 1.

30. Use of a sports surface according to any one of claims 1 to 29 for ball skills.

31. The sports surface is used without deliberately wetting the surface beforehand to improve play, Use of the sports surface according to claim 30.

32. - Providing a backing layer, the backing layer having an upper surface and a lower surface; - Incorporating a plurality of pile fibers into the backing layer so as to stand upright as loops from the upper surface, the loops being connected to each other at the lower surface of the backing layer; - Forming a substantially continuous playing surface by tightly packing the loops comprising A method for manufacturing a sports surface.

33. Further comprising weakening the pile fibers at the lower surface of the backing layer to prevent wire transmission, The method according to claim 32.

34. At least partially melting the pile fibers at the lower surface of the backing layer to prevent wire transmission and / or prevent fiber extraction further comprising The method according to claim 32 or 33.

35. Further thermally stabilizing the sports surface further comprising The method according to claim 32 or 33.

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