JP5794737B2 - Artificial grass - Google Patents

Description

  More specifically, the present invention relates to a technique for improving the durability of a pile in an artificial turf in which a pile is planted on a base fabric.

  Artificial turf filled with fillers between piles is widely used as an artificial turf surface with characteristics similar to natural turf in various athletic facilities such as soccer, rugby and baseball fields. In recent years, taking advantage of the all-weather feature, it has been increasingly used for school grounds year by year, and the utilization rate of artificial grass has been increased.

  As one of this type of artificial turf, a so-called long pile artificial turf is known in which the pile length is set longer than that of a conventional artificial turf. Long pile artificial turf is popular because it can reproduce the properties close to natural turf by filling rubber chips between long piles and lengthening the pile tip exposure.

  By the way, the surface of the artificial turf is loaded with various shoes such as sports shoes with rubber soles from various sports spikes, etc. As the operating rate improves, wear due to friction with various shoe soles and repeated loads As a result, the pile is easily twisted or broken, which causes the tip of the pile to become fibrillated (small fibers).

  In view of this, conventional artificial turf piles have been favorably employed for polypropylene and high-density polyethylene having good wear resistance in order to prevent the above-described fibrillation. For example, see Patent Documents 1 and 2.

  However, in the long pile artificial turf, unlike the conventional structure where the artificial turf with sand is fibrillated, a long protruding pile is repeatedly stepped on and twisting stress is applied, thereby causing the bending and buckling of the pile to break. Fibrilization occurs due to cracks and cracks.

  In addition, artificial turf with a particularly high operating rate is not only concerned with the impact of the turf tip due to the progress of fibrillation, but also due to static electricity. And uncomfortable. Furthermore, since a pile of piles is taken out of the field, the surroundings of the field become dirty, causing problems for managers.

  In addition, conventional artificial turf piles are generally stretched about 5 to 7 times, have high tensile strength but low durability, and it has been difficult to prevent fibrillation as described above. .

Japanese Patent Laid-Open No. 6-184811 Japanese Patent Laid-Open No. 11-269811

  Therefore, an object of the present invention is to provide an artificial turf that does not fibrillate over a long period of time and has stable durability.

In order to achieve the above-described object, the present invention provides an artificial turf in which a pile is planted on a base fabric, wherein the pile has a linear low density polyethylene (L-LDPE) having a density of 0.900 to 0.940. A crystalline plastic made of uniaxially stretched to have a crystal orientation degree of 0.75 to 0.90 (more preferably 0.75 to 0.85) and a tensile modulus of 150 to 350 N / mm ² . It is characterized by being made of flat filament yarn.

  As a more preferred embodiment, the pile has a flatness ratio (W / H) of 3.0 to 7.0, where H is the length in the minor axis direction of the cross section of the pile and W is the length in the major axis direction. In the present invention, the “cross section” refers to a cross section orthogonal to the pile length direction.

  As a more preferred embodiment, the length H in the minor axis direction of the cross section of the pile is 180 to 350 μm.

  According to this, the crystalline plastic is uniaxially stretched and a flat filament yarn having a crystal orientation degree of 0.75 to 0.90 (more preferably 0.75 to 0.85) is used for the pile. Pile flexibility can be increased and stable durability can be achieved without fibrillation over a long period of time.

  Further, when the length in the minor axis direction of the cross section of the pile is H and the length in the major axis direction is W, the flatness (W / H) of the pile is 3.0 to 7.0. It becomes difficult to wear, and as a result, the progress of fibrillation can be prevented.

  Furthermore, when the length H in the minor axis direction of the cross section of the pile is 180 to 350 μm, the durability of the pile is improved. When the length H is shorter than 180 μm, fibrillation tends to occur, which is not preferable. On the other hand, when the length H is longer than 350 μm, the pile becomes thick and not only high in cost, but also easily bends due to bending, and as a result, the flexibility and appearance of the artificial turf are impaired. It is not preferable.

Moreover, the durability of a pile becomes favorable because the tensile elasticity modulus of the said pile is 150-350 N / mm < ² >. A tensile modulus of less than 150 N / mm ² is not preferable because the elastic force is weak and the pile is easily cut and the workability is deteriorated. On the other hand, when the tensile elastic modulus is more than 350 N / mm ² , it is not preferable because the rigidity is increased and bending folds and buckling are easily caused and the flexibility as an artificial grass is impaired.

Sectional drawing which showed typically the artificial grass which concerns on one Embodiment of this invention.

  Next, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited thereto.

  As shown in FIG. 1 (a), this artificial turf 1 is composed of a base fabric 2 formed in a sheet shape with piles 3 planted at a predetermined interval. The backing agent 4 for preventing the pile 3 from being detached is applied.

  As the base fabric 2, for example, a plain woven fabric made of a thermoplastic resin such as polypropylene or polyethylene is used, but other woven fabrics may be used. In the present invention, the form and material of the base fabric 2 are not particularly limited.

  The pile 3 is a flat filament having a crystal orientation degree of 0.75 to 0.90 (more preferably 0.75 to 0.85) by uniaxially stretching a crystalline plastic (also called a crystalline polymer). Made of yarn.

  Referring to FIG. 1 (b), the pile 3 is made of a flat filament yarn. When the length in the minor axis direction of the cross section of the pile 3 is H and the length in the major axis direction is W, the pile 3 The flatness ratio (W / H) is formed within a range of 3.0 to 7.0.

  That is, when the flatness ratio is 3.0 to 7.0, it becomes difficult to wear, and as a result, the progress of fibrillation can be prevented.

  As a more preferable embodiment, the length H in the minor axis direction of the cross section of the pile 3 is 180 to 350 μm (more preferably 250 to 300 μm). That is, when the length H is shorter than 180 μm, fibrillation tends to occur, which is not preferable.

  On the other hand, when the length H is long, the pile becomes thick and the cost becomes high, and it becomes easy to bend a bend due to bending, and as a result, the flexibility and appearance of the artificial turf are impaired.

As a more preferable embodiment, the tensile elastic modulus of the pile 3 is 150 to 350 N / mm ² . That is, when the tensile modulus is less than 150 N / mm ² , the elastic force is weak, the pile is easily cut, and the workability is deteriorated, which is not preferable.

Conversely, when the tensile elastic modulus is more than 350 N / mm ² , it is not preferable because the rigidity increases and bending folds and buckling easily occur and the flexibility as an artificial turf is impaired.

  As a material satisfying the above specifications, linear low density polyethylene (L-LDPE) having a density of 0.900 to 0.940 is used as the crystalline plastic of the present invention. Note that other crystalline plastics may be used as long as each condition described above is satisfied.

  In this example, the pile 3 is composed of a single filament of flat filament yarn having a predetermined fineness (decitex) planted on the base fabric 2, but for example, a plurality of twisted yarns may be used. If each specification mentioned above is satisfied, the usage mode will not be specifically limited.

  The completed artificial turf 1 is laid on a predetermined base 10 and then filled with rubber chips as the filler 5 between the piles 3. In the present invention, the configuration of the filler 5 and the base 10 is as follows. It is not specifically limited, You may change arbitrarily according to a specification.

  Next, specific examples of the present invention were compared and examined together with comparative examples. First, a pile was created by the following method.

[Production of piles]
A linear low-density polyethylene resin composition (density 0.926 g / cm ³ , MFR 0.9 g / 10 min) is melt-extruded using a φ60 mm extruder at a temperature of 180 ° C. and cooled and solidified in a 30 ° C. water bath. Next, after uniaxially drawing at 90 to 100 ° C. using a roll drawing method, relaxation heat treatment was performed in a hot water tank at 90 to 100 ° C. to obtain an artificial turf yarn having a fineness of about 1850 dtex.

[Production of artificial grass]
The pile produced by the above method is twisted into a bundle of six pieces to form one pile. Using a 5/16 gauge tufting machine, a pile height (pile length from the base fabric to the tip) is applied to a polypropylene plain woven fabric. A) After planting to 60 mm, 70% SBR latex was applied at a coating amount of 1100 g / m ² on the back side of the base fabric and dried at a high temperature of 105 ° C. to obtain artificial turf.

  Next, measurements and various evaluations were performed on the produced piles and artificial turf by the following methods.

(Measurement of crystal orientation)
Set the surface of the pile yarn on the sample stage so as to be perpendicular to the X-ray irradiation direction, and use an X-ray diffractometer (model number: D8-DISCOVER-μHR-Hybrid) manufactured by Bruker-AXS The degree of crystal orientation was calculated from the half width of the intensity distribution obtained from the peak of the obtained diffraction pattern after irradiation with X-rays under the following conditions.
〔Measurement condition〕
X-ray source: CuKα ray (multilayer mirror specification)
Output: 50kV, 22mA
Detector: Scintillation counter

(Measurement of tensile modulus)
The pile yarn is cut to a length of 50 mm, set in a tensile tester with 30 mm between chucks, and then pulled until the pile yarn breaks at a tensile speed of 100 mm / min, and its tensile load-strain curve (SS curve) ) And the tensile modulus was calculated from the tangential gradient in the elastic deformation region.

[Evaluation of durability]
The artificial turf is cut out into a disk shape of φ100 mm and stored in the bottom of a bottomed cylinder container having the same diameter, and the rubber chip is filled to the extent that the turf tip is exposed 20 mm. The artificial turf is pressed with a load of 700 N by a compressor that can be inserted along the inner peripheral surface of the cylinder container. At the tip of the compressor, urethane rubber having a hardness of 60 having a lattice-like unevenness in the image of a shoe sole is attached.

  With the artificial turf pressed with a compressor, the cylinder container was reciprocated at a rotational speed of 25 rpm and an angle of 15 °, and one endurance test was performed for 100,000 counts. After the implementation, 10 artificial turf piles were randomly extracted, and the number of cracks was counted. If the number of occurrences was 0, ◎, if 1-3, ○, 4 or more were judged as x. .

[Evaluation of workability]
In the present embodiment, workability refers to the cutting characteristics of an artificial turf pile. After planting the pile on the artificial turf with a tufting machine, the height was cut uniformly so that the pile length would be 60 mm, and there were no defects such as loops remaining. Was evaluated as x.

[Evaluation of appearance properties]
Each artificial turf and natural turf by 10 athletes was observed, and when the size, shape, texture and landscape were at the same level, the feeling felt by 7 or more was evaluated as ○, and the case of 6 or less was evaluated as ×.
〔Comprehensive evaluation〕
Finally, comprehensive evaluation of durability, workability and appearance was performed. As for the evaluation method, in each of the above evaluations, in all cases, the case of ○ or ◎ was “◯”, and if there was at least one ×, it was “×”.

Example 1
[Crystal orientation] 0.81
[Short shaft length H] 0.235mm
[Long axis length W] 1.16mm
[Flat ratio W / H] 4.936
[Tensile modulus] 190 N / mm ²
[Durability] ◎
[Machinability] ○
[Appearance] ○
[Comprehensive evaluation] ○

Example 2
[Crystal orientation] 0.75
[Short shaft length H] 0.196mm
[Long axis length W] 1.37mm
[Flat rate W / H] 6.990
[Tensile modulus] 206 N / mm ²
[Durability] ◎
[Machinability] ○
[Appearance] ○
[Comprehensive evaluation] ○

Example 3
[Crystal orientation] 0.90
[Short shaft length H] 0.243mm
[Long axis length W] 1.12mm
[Flat ratio W / H] 4.609
[Tensile modulus] 273 N / mm ²
[Durability] ○
[Machinability] ○
[Appearance] ○
[Comprehensive evaluation] ○

Example 4
[Crystal orientation] 0.85
[Short shaft length H] 0.271mm
[Long axis length W] 0.91mm
[Flat ratio W / H] 3.358
[Tensile modulus] 301 N / mm ²
[Durability] ◎
[Machinability] ○
[Appearance] ○
[Comprehensive evaluation] ○

<Comparative example 1>
[Crystal orientation] 0.92
[Short shaft length H] 0.237mm
[Long axis length W] 1.11mm
[Flat ratio W / H] 4.684
[Tensile modulus] 357 N / mm ²
[Durability] ×
[Machinability] ○
[Appearance] ○
[Comprehensive evaluation] ×

<Comparative example 2>
[Crystal orientation] 0.91
[Short shaft length H] 0.150mm
[Long axis length W] 1.80mm
[Flat ratio W / H] 12.000
[Tensile modulus] 348 N / mm ²
[Durability] ×
[Machinability] ○
[Appearance] ○
[Comprehensive evaluation] ×

<Comparative Example 3>
[Crystal orientation] 0.72
[Short shaft length H] 0.220mm
[Long axis length W] 1.12mm
[Flat rate W / H] 5.091
[Tensile modulus] 195 N / mm ²
[Durability] ○
[Machinability] ×
[Appearance] ○
[Comprehensive evaluation] ×

  A summary of Examples 1-4 and Comparative Examples 1-3 is shown in Table 1.

As mentioned above, the following knowledge was acquired by the Example and the comparative example. That is,
-By suppressing the degree of crystal orientation, it is rich in flexibility and effective against repeated buckling and twisting.
-If the degree of crystal orientation is small, the stickiness will increase and the stability will deteriorate.
-If the minor axis length (thickness) is increased, the cutting blade becomes difficult to enter, so that the cutting stability is deteriorated.

1 Artificial grass 2 Base cloth 3 Pile 4 Backing agent 5 Filler 10 Base

Claims (4)

In the artificial turf in which a pile is planted on a base fabric, the pile is formed by uniaxially stretching a crystalline plastic made of linear low density polyethylene (L-LDPE) having a density of 0.900 to 0.940 , An artificial turf comprising a flat filament yarn having a degree of crystal orientation of 0.75 to 0.90 and a tensile modulus of 150 to 350 N / mm ² . The pile has a crystal orientation of 0 . The artificial turf according to claim 1, wherein the artificial turf is 75 to 0.85.   The flatness (W / H) of the pile is 3.0 to 7.0, where H is the length in the minor axis direction of the cross section of the pile and W is the length in the major axis direction. Item 3. The artificial turf according to Item 2.   The artificial turf according to claim 3, wherein a length H in a minor axis direction of a cross section of the pile is 180 to 350 µm.

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