JP2008045264A - Thread for synthetic grass turfs, die for producing same, related processes of manufacturing and use, and synthetic grass turf including it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thread for synthetic grass turfs, die for producing the same and related process of manufacturing and use, and a synthetic grass turf including it. <P>SOLUTION: A yarn (B') for forming filiform formations of a synthetic-grass covering reproducing the grassy sward of natural turf comprises a plurality of filiform segments (B1') set alongside one another and connected together by thin breakable connection portions (B2'), in which the filiform segments (B1') present thickened end parts. Preferably the yarn (B') is obtained by longitudinal stretching, starting from a length (B) constituted by a strip comprising a plurality of filiform segments (B1) set alongside one another and connected together by thin connection portions (B2). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to synthetic (or “artificial”) turf covers.

  At present, synthetic grass covers are used extensively to provide a green zone for decorating the city in detail and to provide similar comfort to the border area of the swimming pool, and also in general In particular, it is very widely used as an alternative to natural turf covers when it appears that planting and maintenance of natural turf covers is difficult considering all conditions. The use of this synthetic grass cover has recently received a new stimulus to provide a cover for sports equipment, such as a soccer pitch. Corresponding references are US-A-3 731 923, US-A-4 337 283, US-A-5 958 527, US-A-5 961 389, US-A-5 976 645, JP-B-32. 53 204, JP-A-10037122, DE-A-44 44 030, EP-A-0 377 925, and EP-A-1 158 099, etc. is there.

  In particular, the synthetic turf structure, which is known from the last document cited in the name of the applicant of the present application, is a sheet-like substrate on which a plurality of thread-like structures are extended in order to simulate a grassland by natural turf, And a fine filler, i.e., an infill dispersed between the thread-like structures to maintain the thread-like structure itself in a substantially upright state. The synthetic grass cover is characterized in that, inter alia, the fine filler (infill) is constituted by a substantially homogeneous mass of particulate material selected from the group consisting of polyolefin-based materials and vinyl polymer-based materials. Yes.

  EP-A-1 319 753, EP-A-1 375 750, EP-A-1 371 779 and EP-A-1 486 613 and also European Patent Application No. 05425957.7 have other benefits relating to the above solution. It describes about the development. All the documents mentioned above are in the name of the applicant of the present application.

  In the last few years, with respect to the application in the production of lawn covers for sports equipment, the activity of innovation has been focused mainly on the filler, ie the properties and distribution methods of the infill.

  Accordingly, much attention has not been paid to the characteristics of the yarn used to produce the above thread-like structure as a whole. With regard to yarn properties, for example, not with regard to infill properties and distribution methods, but with regard to the possibility of using different compositions, in particular yarns obtained by the co-extrusion of polymer materials with different friction coefficients, in synthetic grass covers. See EP-A-0 259 940 as described.

  A solution that is still widely used to produce the above-described thread-like composition may be to rely on yarns having a base of plastic material such as polyethylene. This material is first laminated to form a sheet, i.e. web, having a thickness of, for example, 200-300 microns. Next, the sheet is cut by a cutting process and divided into a very large number of strips having a narrow width (for example, 10 to 20 mm).

  Usually, following the cutting step, one or more longitudinal stretching and fibrillation steps are performed. For this purpose, the web is divided into strips of a given width and subsequently stretched before a prefibrillation step. That is, during normal use, the thread is cut in the longitudinal direction so that the thread gradually becomes thinner in the width direction. The material is gathered as a ribbon or tape on a bobbin or reel and is typically handed over to the next step of twisting the threads and can therefore be processed in subsequent processing steps (eg, lofting on a loom).

  In order to facilitate production at every step of the process, the above types of yarn are initially marketed in large quantities. The final aesthetic of the yarn is not optimal in terms of reproducing the appearance of the lawn in the natural turf cover, but is considered acceptable in the market. The disadvantage that this type of yarn is unavoidable is that after 4 to 5 years from laying, the corresponding cover is subject to wear due to uncontrolled and excessive uncutting during use and uncontrolled overcutting. It exposes the problem (destruction of part of the thread with the possibility of dust being formed by the destruction / degradation of the thread, formation of a very thin and brittle strip, etc.).

  Alternative techniques envisage forming single threads or single strand yarns directly from the thread die via the formation of individual threads. This thread is stretched and gathered into four, six or eight threads per bunch and then handed over to the next step as described above (gathered, twisted, tufted. ) Since this technique does not have the wear problems described above in connection with fibrillated yarns, this technique is highly asserted in the market. Single strand yarns are not always exposed to undesirable phenomena such as cracking or shredding. However, the single thread technique has various weaknesses. First of all, it is difficult to manufacture individual threads on a reel (when these threads are grouped together into groups of 4, 6, or 8 threads). And, if not so, the process of twisting the thread is equally difficult. In the final product, the strength / toughness that secures the thread to the substrate of the synthetic grass cover is accepted by the market and is in compliance with the existing technical requirements. The strength / stickiness of the “made” substance is incomparable. This means that the individual (single) threads that make up a single tuft can slide against each other at points where the loop is also fixed to the substrate (typically using latex) It can be explained by having

  For the sake of completeness, it should be recalled again that there is a third type of yarn, defined as “monotape”, which constitutes a kind of hybrid between the yarns described above. In the case of a manufacturing process, in fact, following the manufacturing cycle represented for the fibrillated product described at the beginning, any pre-fibrillation process from the original sheet or narrower web strip is used. The subsequent cutting is followed by the gathering of 4, 6, or 8 strands per bunch and delivery to subsequent processes. This technique, which has various problems, is virtually disappearing from the market with little commercial success.

  From WO-A-2004 / 106601 taken as an example of the preamble of claim 1, a technique is known in which a multi-layer strip is obtained from a membrane extruded from a thread die through a nozzle with a protrusion. This protrusion forms a groove in the strip that is designed to form a preferred site for splitting the strip during fibrillation. Thus, it is stated in the claims that subsequent random postfibrillation of the yarn to reduce the elastic energy of the synthetic grass cover is avoided.

  As already mentioned, no matter what manufacturing technique is employed, the yarn is usually made of a synthetic grass cover of the type described above, i.e. a synthetic grass cover with a thread-like structure extending from a sheet-like substrate. It is wound on a reel that is used to supply a workstation for manufacturing the basic structure. The workstation typically operates using known techniques similar to techniques such as tufting.

  In particular, the technique applies a yarn composition having a general U-shaped configuration to a sheet-like substrate (either a continuous substrate or a substrate that is substantially continuous due to, for example, drainage holes). The purpose is to “plant”. Each of the constructs is basically a kind of loop with a portion passing directly under the substrate and two lateral branches extending vertically above the substrate to simulate a lawn leaf. It constitutes a bunch. In the case of a single thread, the tuft is composed of four, six or eight strands or leaves, depending on the thickness and / or width of the individual leaves.

  Overall, although satisfactory, these conventional techniques leave room for further improvement in many ways.

  In particular, it substantially incorporates the advantageous aspects of the various techniques described above and eliminates their drawbacks, in particular, the subsequent stability to shredding typical of single strand yarns. And fibrillated yarns that provide resistance and thus avoid the very disadvantageous side combined with the need to combine multiple (single) threads to form a single tuft, while tethering to a substrate There is a keen need for techniques to produce yarns for lawn covers that ensure typical strength / toughness. This is achieved within the context of a manufacturing process that is simpler, more reliable, effective, and has the potential to achieve further improvements in terms of fidelity in reproducing the appearance of the lawn in natural turf covers. .

  According to the present invention, this need is met by yarns having the characteristics that are explicitly described in the claims. The invention also relates to a corresponding method for producing said yarn as well as a synthetic grass cover (either synthetic grass cover with infill or synthetic grass cover without infill). It is about how to do.

  The claims form an integral part of the technical disclosure provided herein in connection with the present invention.

  The present invention will now be described with reference to the accompanying drawings, which are merely non-limiting examples.

  In FIG. 1, reference numeral 10 represents an entire plant that can be used to produce yarns used to produce synthetic grass covers.

  The plant 10 is shown in the form of a set of processing stations, where the processing stations are arranged at a single site and have a processing cycle consisting of different processing steps that are executed sequentially in stages. It can be designed to perform. However, it will be appreciated by those skilled in the art that the processes described above can be performed with different assumptions or contexts, and can be performed at different times before and after storage and / or transport of the intermediate product in the various processing steps shown in the figures. Easy to understand.

  In detail, reference numeral 12 represents an extruder for plastic material operating in the direction of the vertical axis. Molten plastic material is supplied to the extruder 12 via the inlet duct 14 and is extruded in a thread die 16 constituted by a die with an annular profile, for example.

  In particular, in the exemplary embodiment described herein, which is provided merely as an example, the annular thread die 16 is a specific number of, for example, separated from one another by a spacing of 1-2 cm. An arcuate portion 160 is formed. The individual portions 160 of the thread die are each designed to produce a strip B and have the contour shown in FIG. For example, FIG. 2 is a plan view from directly below a single arched portion 160 of a thread die, as viewed ideally from below, that is, from an area where individual strips B fall as they are fed from the thread die. Can be considered.

  In particular, the single portion 160 of the thread die has a specific length (eg, 50-60 mm, typically 56.4 mm) measured along its arcuate extension path, and a specific There are a number of segments 162 (eight in the embodiment shown in the figure).

  Also, each of the segments 162 is a length measured along an arcuate extension path of constant length (also a single portion 160 of the thread die (the segment forms part of it)) in a 6.7 mm area. ) And connected to adjacent segments 162 by a thin portion or stretch 164 (or in the case of two end segments 162 of a single portion 160 in a thread die, connected to adjacent segments).

  Each of the thin portions 164 has a length of, for example, 0.4 mm and a width or thickness of, for example, 0.15 mm (a radial dimension relative to the extension path of the single portion 160 of the thread die).

  An important feature of the segments 162 is that they have a U-shaped cross section, so that each of the segments 162 is wider than the central portion 1622 (also relative to the arcuate extension path of the single portion 160 of the thread die). Radial dimension) with two end portions or branches 1620.

  For clarity of illustration, FIG. 2 shows a segment in which a wide end portion 1620 and a central portion 1622 that is narrower than the end portion 1620 occupy positions on both ends of a single portion 160 in the thread die shown. Only 162 is clearly indicated with a corresponding reference number.

  On the other hand, the features of the distal portion 1620 that are wider than the central portion 1622 can also be achieved using other shapes (eg, a “bone” shape), so the U-shape is considered the only shape. It will be understood that it must not.

  By way of example only, the end portion 1620 is 0.67 mm wide or thick (as opposed to the arcuate extension path of the single portion 160 of the thread die) relative to the 0.46 mm width or thickness of the central portion 1622. Radial dimension).

  On the other hand, all dimension values referred to above are given merely as examples and should not be construed as limiting the scope of the invention described herein in any way. It is clear.

  Accordingly, there are a plurality of strips B at the exit portion of the thread die 16, and each of these strips B has the contour shown in FIG. 3 when viewed in cross section. This contour, in other words, is complementary to the contour of the single part 160 of the thread die described above with reference to FIG. 2, and therefore, in this contour, the specifics interconnected by the elongated portion B2 Number of segments B1 (eight in the example shown in the figure) can be distinguished, each segment B1 having a profile with an end portion wider than the central portion (implementation shown here) In the example, it is generally U-shaped).

  The material used to form the strip B is usually a polyolefin-based material, such as a material selected from the group consisting of polyethylene, polypropylene and / or mixtures and / or copolymers thereof. Currently, it is preferred to select polyethylene.

  This material is usually colored, thereby typically giving a green color throughout. Obviously, this feature should not be understood in any way as limiting the scope of the invention.

  Usually, the strip B sent out from the thread die 16 is immersed in a cooling tank housed in the tank 18 and cooled so that they can be strengthened.

  As already mentioned, each of the strips B reproduces the outline of the withdrawal provided by the individual portions 160 of the thread die, so that the form of the strips B are arranged side by side and more elongated. It is in the form of a strip constituted by a plurality (for example 8) of thread-like elements B1 (with wide ends and thus thicker than the central part) connected together by a connecting part B2.

  Typically, each of the strips B will tend to stretch when immersed in the cooling bath 18, so that the actual and dimensional consistency of the shapes for the individual portions 160 of the thread die will usually correspond. Absent. For example, the strip B can provide a constant width in an area of 20 mm, and a segment B1 and an elongated portion B2 having a correspondingly sized width are 2.4 mm and 0.12 mm, respectively.

  Instead, the thickness dimension for segment B1 (the maximum thickness of the region corresponding to the thick end) and elongate portion B2 can be about 300 microns and about 30 microns, respectively.

  All dimensional values quoted throughout this description are provided as examples only and are not to be construed as limiting the scope of the invention described herein in any way. I want to remind you once again that we must not.

  In any case, it is preferred that the elongated connecting portion B2 has a thickness sufficient to prevent it from becoming brittle under normal handling of the strip B. The “regular handling state” means a state corresponding to the fact that the strip B is grasped by a human hand and touched, for example by wrapping around its finger.

  Cooled strips B or individual strips B (the solutions shown here for the simultaneous formation of multiple strips B are preferred and non-forced embodiments of the present invention only) Is then fed to the drawing assembly using a roller, indicated generally at 20, driven by an electric motor, for example.

  One or more strips B can be wound up in the course of a continuous process (in this case, typically one extraction assembly 20 will be provided for each strip B) or in the course of an intermittent process. In this case, it is conceivable to gradually empty the web / strip B tank 18 which is gradually accumulated.

  Similarly, it is understood that reliance on immersion cooling techniques is only one of many possible options for achieving the desired cooling / enhancement results for one or more strips B. Will. Other techniques for achieving cooling by exposure to the environment or by exposure to air or a gaseous jet, for example, to cool as it is delivered from the thread die 16 are also contemplated.

  Starting from the drawing assembly 20, one or more strips B (for simplicity of handling, only one strip will be referred to hereinafter) are fed to the assembly 22 for stretching in the longitudinal direction.

  This assembly usually consists of an oven and a plurality of sets of motor driven rollers for heating the material in a manner known per se. Each of the motor drive rollers comprises two rollers that rotate in opposite directions, between which the strip B gradually has a circumferential or tangential speed (and hence the speed imparted to the strip B) of the pair of rollers. It moves forward at a faster speed (from left to right as shown in FIG. 1).

  According to this method, an overall longitudinal stretching action is applied to the strip B in one or more stages. For example, a stretch ratio between 4: 1 and 5: 1 may be applied, understood as a ratio between the ratio of advancing the latter stage of the heating / stretching oven and the ratio of advancing the preceding stage of the heating / stretching oven. (In a manner known per se).

  FIG. 4 shows the overall effect of this stretching, where the reference sign B ′ represents the strip delivered from the stretching unit 22.

  The stretched strip B ′ (hereinafter also referred to as “yarn” for the sake of brevity) has a width and thickness that is narrower and thinner than the width and thickness of the starting strip B, but during stretching The cross-sectional profile is virtually unchanged (for well-known physical reasons).

  Thus, similarly, the yarn B ′ obtained by stretching, when viewed in the cross section shown in FIG. 3, is arranged side by side and a plurality of thread segments B1 ′ connected together by a more elongated connection portion B2 ′. For example in the form of a strip having a width of 9-10 mm (as in the case of its “length” from which strip B was obtained). Segment B1 'has a thick end portion.

  For example, in the case of yarn B ', segment B1' may have a width of 1.1 to 1.3 mm and a thickness of 130 to 150 microns (the maximum thickness of the region corresponding to the thick end). Instead, the elongated connection portion B2 'can typically have a width of about 30 microns and a thickness of 10 microns in the thinnest region.

  Again, the foregoing dimensional values are provided as examples only and should not be construed as limiting the scope of the invention described herein in any way. I want to recall.

  In any case, the elongated portion B2 ′ is very fragile, so that a single yarn B ′ winds the yarn B ′ around the reel R depending on the appropriate stress, eg method, and the introductory part of this description. Is easily fibrillated by breaking the elongated portion B2 'by stress as obtained by a twisting process generally performed for the purpose described in the above, i.e. each one of the segments B1'. Can be divided into individual threads corresponding to. Thus, the strip B 'behaves as a true strip with all the resulting advantages until the twisting process in which the strip is then divided into individual strands.

  In FIG. 1, reference numeral 24 is generally designated S, wound on a reel R, which operates according to standards known per se (ie, basically operates according to techniques such as tufting). 1 represents a processing station that allows formation starting from yarn B ′ of synthetic grass cover.

  This is basically a synthetic turf structure S provided with a sheet-like substrate K on which a plurality of thread-like structures (constituted by yarns B ') simulating a grassland with a natural turf cover extend.

  Specifically, the weave station 24 has a loop portion L passing directly under the substrate K, and a yarn B having two lateral branches extending vertically above the substrate K and simulating grass leaves. It operates by “planting” the sheet-like substrate K with a composition of “a kind of tufts” individually.

  The synthetic turf structure S receives a filler in which the fine substance F is dispersed between the thread-like structures in order to maintain the thread-like structures themselves in a substantially upright state (again generally known as well). Suitable for according to the criteria). For example, the particulate filler (infill) F may be composed of a substantially homogeneous mass of particulate material selected from the group consisting of a material with a polyolefin base and a material with a vinyl polymer base. it can.

  In any case, the operating characteristics of the weave station 24 and the manufacturing standards for the synthetic grass cover S do not constitute a particular critical element for the purposes of understanding and practicing the present invention. The solution according to the invention is in fact also suitable for use in the context of a synthetic grass cover manufactured according to a different standard than the synthetic grass cover shown in FIG.

  For example (and without intending any obvious limitation on the scope of the present invention), the thread-like structures extending above the sheet-like substrate K can be used instead of freeing their distal ends (see FIG. 4). Can be connected to each other (according to the configuration such as plush or velvet shown) to create a loop composition

  FIGS. 6 and 7 show the yarn B ′ having a certain length before and after the separation of the individual segments B1 ′, which are initially obtained by breaking the elongated portions B2 ′ connecting the segments themselves. Appearances are shown respectively. Segment B1 'maintains its specificity accurately even after it has been separated without further fragmentation.

  Unlike the events that occur in conventional types of fibrillation processes, the structure of the yarn B ′ means that the yarn B ′ itself results in a plurality of thread-like elements B1 ′, for example its features are precisely defined, Thus, according to the presently preferred and non-mandatory embodiment, the thread elements B1 ′ are substantially the same as each other.

  The phrase “an embodiment that is currently preferred but not limited to” refers to dimensions that are not the same as each other but different in some applications (eg, “wide” and “narrow” dimensions). It is intended to take into account the fact that the thread-like segment B1 ′ providing the following (thus the segment B1 shown in FIG. 3 and the segment 1600 in the individual part 160 of the thread die) can be considered preferred.

  Whatever the choice, the solution described herein in each case is one of several conventional disadvantages associated with the fibrillation process, namely the individual leaves of the yarn. Irregular shredding (virtually random shredding) is prevented, and in turn, the formation of microfibers of different widths, which often break with minimal stress and are often thin enough to be crumbly, are prevented. . At the same time, according to the solution described herein, the manufacturing standards for the synthetic grass cover S do not change significantly, particularly with regard to the development of the “weaving” process of the synthetic grass cover. In particular, the (somewhat cumbersome) steps inevitably necessary for the single thread technique, i.e. collecting a certain number of single threads to form tufts, are avoided.

  Similarly, those skilled in the art will appreciate that the process of separating the segment B1 '(i.e., breaking the elongate portion B2') will never cause the yarn B 'to be twisted again.

  As an example only, the step of separating the segment B1 ′ (the step of breaking the elongate portion B2 ′) is performed after weaving the yarn B ′ into the substrate K and then for example of a synthetic grass cover formed by the yarn B ′. It can be performed or completed by a brushing process. This brushing step is performed by, for example, using a rotating brush that applies mechanical stress to the yarn B 'to bring the yarn itself into a state immediately before cutting in a region corresponding to the elongated portion B2'.

  In this regard, without being bound by any particular theory, the Applicant has, for example, simply twisted one or more strips B ′, of which the segment itself initially forms part thereof. Subsequent to the accuracy of separating the segments B1 ′ from each other as well as the fact that after separation the segments accurately maintain their unique specificity without further fragmenting them, The mechanism of formation (and formation of the strip B obtained by its stretching), ie the segment B1 ′ (and B1), provides a thicker end part than the central part (each elongated between the end parts) Threads having end portions 1620 with portions B2 'and B2 extending) and thus segments 162 wider than center portion 1622 There is reason to believe that it is bound firmly to being derived from the individual portions 160 of Lee.

  Naturally, structural details and embodiments are described herein merely as non-limiting examples without departing from the principles of the invention and, therefore, without departing from the scope of the invention as defined in the claims. And changes can be made to the content described in the drawings and shown in the drawings.

1 is a functional block diagram of a plant for producing yarn of the type described herein. FIG. FIG. 3 is a plan view illustrating a portion of a thread die used to form a yarn of the type described herein. FIG. 3 shows a yarn in two subsequent steps of the manufacturing process. FIG. 3 shows a yarn in two subsequent steps of the manufacturing process. FIG. 6 is a schematic diagram illustrating criteria by which synthetic (ie, “artificial”) turf covers can be manufactured using the yarns described herein. FIG. 2 shows a yarn immediately after production of the type described herein. FIG. 3 shows a yarn of the type described herein after mechanical stress has been applied in a subsequent step.

Claims (18)

  Yarn (B ′) for forming a thread-like composition of a synthetic grass cover (S) that reproduces grassland with natural turf, arranged side by side, and a breakable thin connection (B2 ′) A yarn comprising a plurality of thread segments (B1 ') connected together by a thread, wherein said thread segments (B1') provide a thick end portion.   Yarn according to claim 1, characterized in that the thread-like segment (B1 ') has a U-shaped profile in cross section.   3. Yarn according to claim 1 or 2, characterized in that the thin connecting portion (B2 ') has a thickness substantially equal to 10 microns at the breakable portion.   4. Yarn according to any one of claims 1 to 3, characterized in that the filamentous segments (B1 ') are substantially identical to one another.   The yarn according to any one of claims 1 to 4, wherein the yarn (B ') is made of a polyolefin-based material.   The yarn according to claim 5, characterized in that the polyolefin-based material is selected from the group consisting of polyethylene, polypropylene and / or mixtures thereof and / or copolymers thereof.   The yarn according to claim 5, wherein the polyolefin-based material is polyethylene.   The yarn according to any one of claims 1 to 7, wherein the yarn is formed from a material (B) subjected to a drawing treatment.   9. Yarn according to any one of claims 1 to 8, characterized in that the material (B) drawn through the thread die (16) is obtained as a starting material.   A thread die for forming a yarn according to any one of the preceding claims, wherein at least part of the thread die (160) comprises a plurality of segments (162) arranged side by side. The plurality of segments having thin connecting portions (164) extending between the segments and arranged side by side provide an end portion (1620) that is wider than the central portion (1622). Thread die.   11. A thread die according to claim 10, characterized in that it comprises a plurality of portions of a thread die (160) extending generally along an annular path. A method for producing a yarn according to any one of claims 1 to 9, comprising:
Providing said yarn (B ') of a predetermined length (B), said predetermined length (B) being arranged side by side and connected together by a thin connection part (B2) A step constituted by a strip with a plurality of threaded segments (B1) formed;
Stretching the predetermined length of yarn (B) longitudinally to form the yarn (B ′).   Forming said predetermined length of yarn (B) with said thin portion (B2) that cannot be broken under normal handling conditions of said predetermined length of yarn (B). The method according to claim 12.   14. The method of claim 12 or claim 13, comprising forming the predetermined length of yarn (B) with the thin portion (B2) providing a minimum thickness of substantially 30 microns. The method described.   A method of using a yarn according to any one of claims 1 to 9 for producing a synthetic grass cover (S), wherein the plurality of said plurality of yarns are broken by breaking the thin connecting portion (B2 '). The yarn segments (B1 ′) are separated from each other, and stress is applied to the yarn (B ′) so that the separated filamentous segments (B1 ′) constitute a filamentous structure that reproduces grassland by natural grass. A method comprising the steps of:   16. The method according to claim 15, characterized in that the step of applying stress to the yarn (B ') comprises twisting the yarn (B').   The method according to claim 15 or 16, characterized in that the step of applying stress to the yarn (B ') comprises brushing the yarn (B').   A synthetic grass cover (S) comprising a synthetic grassland constituted by the yarn (B ') according to any one of claims 1 to 9.