JP2018003274A - Artificial lawn - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing an artificial turf capable of maintaining play performance by reducing catching of spikes or the like on a pile while suppressing scattering of a filler. An artificial turf is provided. The artificial turf includes a base material, a large number of piles imitating turf leaves standing on the base material, and a filler filled to form a filler layer between the large number of piles. The large number of piles includes two or more types of piles including a first pile and a second pile having different rigidity. The second pile has a shorter turf length and lower rigidity than the first pile. [Selection diagram] Fig. 1

Description

  The present invention relates to an artificial turf having a large number of piles simulating turf leaves and a method for producing the same.

  In recent years, artificial turf has become widespread in various athletic facilities such as a soccer field, a rugby field, and a baseball field. Artificial turf is often manufactured by planting a large number of piles imitating turf leaves on a substrate. Further, a filler for protecting the pile is often filled between the piles (see, for example, Patent Document 1). Such fillers can also improve the performance of competition on artificial turf, specifically, adjusting the degree of ball movement used in the competition, controlling the ease of running of the players, It also serves as a cushioning material to prevent players from being injured during play.

JP 2011-58165 A

  On the other hand, it is not preferable that the filler jumps during the competition. In Patent Document 1, two types of piles with different cross-sectional shapes are planted so that some of the piles are inclined, thereby increasing the surface area of the piles that reflect sunlight and suppressing the temperature rise of the artificial turf It is disclosed that a pile that is inclined at the same time can suppress the jumping of the filler.

  However, a long pile may be difficult to fall over due to an adjacent pile. Even if you can fall down well, if the pile is long and hard (high rigidity), it may be easily caught by the spikes of players playing on the artificial turf, which may reduce the playing performance of the competition. .

  An object of the present invention is to provide an artificial grass and a method for manufacturing the same that can suppress the scattering of the filler and reduce the number of catches such as spikes on the pile and maintain the play performance.

  The artificial turf according to the first aspect of the present invention is filled to form a base material, a number of piles imitating turf leaves standing on the base material, and a filler layer between the number of piles. And a filler. The multiple piles include two or more types of piles including a first pile and a second pile having different rigidity. The second pile has a shorter turf length and lower rigidity than the first pile.

  The artificial turf according to the second aspect of the present invention is the artificial turf according to the first aspect, and the second pile has a turf length shorter by 5% or more than the first pile.

  The artificial turf according to the third aspect of the present invention is the artificial turf according to the first aspect or the second aspect, and the first pile and the second pile have different cross-sectional shapes.

The manufacturing method of the artificial turf concerning the 4th viewpoint of the present invention includes the following steps.
(1) A step of manufacturing two or more kinds of yarns including a first yarn and a second yarn having a higher heat shrinkage rate and lower rigidity than the first yarn.
(2) By implanting the two or more types of yarn on a base material, a turf leaf including a first pile formed from the first yarn and a second pile formed from the second yarn is simulated. Manufacturing the intermediate of the artificial turf having a large number of piles composed of two or more types of piles.
(3) placing the intermediate in a high temperature environment and heat shrinking the pile.

  The artificial turf manufacturing method according to the fifth aspect of the present invention is the manufacturing method according to the fourth aspect, wherein the step (1) is more than the thermal contraction rate of the first yarn than the thermal contraction rate of the first yarn. Annealing the first and second yarns under different conditions so as to increase the rate.

  An artificial turf manufacturing method according to a sixth aspect of the present invention is the manufacturing method according to the fifth aspect, wherein, in step (1), the annealing temperature for the first yarn is higher than the annealing temperature for the second yarn. Is also expensive.

  An artificial turf manufacturing method according to a seventh aspect of the present invention is the manufacturing method according to the fifth aspect or the sixth aspect, wherein in the step (1), the annealing time for the first yarn is the second yarn. Longer than the annealing time.

  An artificial turf manufacturing method according to an eighth aspect of the present invention is the manufacturing method according to any one of the fourth to seventh aspects, wherein the step (1) includes the steps of the first yarn and the second yarn. Forming a cross-sectional shape different from each other.

  ADVANTAGE OF THE INVENTION According to this invention, artificial turf provided with two or more types of piles from which rigidity differs as many piles imitating turf leaves is provided. Of these piles, the second pile has a shorter turf length and lower rigidity than the first pile. That is, since the second pile having a lower rigidity and more easily falls is formed shorter, the adjacent pile is less likely to prevent the second pile from falling, and the second pile is more likely to fall. Therefore, the second pile becomes an “umbrella” and scattering of the filler can be suppressed. In addition, since the second pile, which has a lower rigidity and is easy to fall, is formed shorter, the number of catches such as spikes on the fallen second pile is reduced, and the play performance can be maintained.

The side view of the artificial turf concerning one embodiment of the present invention. The figure which shows the example of the cross-sectional shape of a 1st pile and a 2nd pile. The schematic diagram which shows the intermediate body before heat shrink by the drying process of a backing layer, and the artificial grass after heat shrink.

  Hereinafter, an artificial turf and a manufacturing method thereof according to an embodiment of the present invention will be described with reference to the drawings.

<1. Artificial grass>
The artificial turf 1 according to the present embodiment is installed on an installation surface such as an asphalt surface or the ground in various sports competition facilities such as a soccer field, a rugby field, and a baseball field. As shown in FIG. 1, the artificial turf 1 has a base material 2 and a large number of piles 3 simulating turf leaves standing on the base material 2. The base material 2 is formed in a sheet shape, and the pile 3 is planted on the base material 2 at a predetermined interval. In addition, a backing agent is applied to the back side of the base material 2 to prevent the pile 3 from falling off, and a backing layer 4 is formed.

  Although the material and form of the base material 2 are not particularly limited, for example, the base material 2 can be formed as a plain woven fabric made of a resin material. Typically, a thermoplastic resin such as polypropylene or polyethylene can be selected as the resin material.

  The material and form of the pile 3 are not particularly limited as long as the appearance of the turf can be realized. For example, the pile 3 can be formed using flat filament yarn (yarn) made of a resin material. . Typically, a thermoplastic resin such as polyethylene or polypropylene can be selected as the resin material. Moreover, the pile 3 of this embodiment is being fixed with respect to the base material 2 by sewing the plastic thread | yarn (yarn) used as the pile 3 into the base material 2 using a tufting machine.

  The material of the backing layer 4 is also not particularly limited. For example, the backing layer 4 can be composed of a mixture of polyethylene and SBR latex. The backing layer 4 can be omitted.

  A filler 5 is filled between the piles 3 on the surface of the substrate 2. In addition to protecting the turf, the filler 5 can also serve as a cushion material for preventing the player from being injured during play. In addition, the filler 5 can adjust the degree of ball movement used in the competition and can control the runnability of the players, and can improve the performance of the competition on the artificial turf 1. it can.

  As the filler 5, at least one of an elastic filler 5a and a hard filler 5b can be used. As the elastic filler 5a, for example, a rubber chip made of crushed waste tire or the like can be used. As the hard filler 5b, for example, sand can be used. In the example of FIG. 1, both the hard filler 5 b and the elastic filler 5 a are filled between the piles 3.

  The pile 3 on the base material 2 includes a plurality of types of piles 3 having different rigidity. In this embodiment, two types of piles 3 having different rigidity are planted on the base material 2, and these piles are hereinafter referred to as a first pile 3 a and a second pile 3 b. In the present embodiment, the first pile 3a and the second pile 3b are made of the same material, but have different cross-sectional shapes. As a result, the rigidity of the second pile 3b is lower than that of the first pile 3a. It is configured as follows. The cross-sectional shapes of the first pile 3a and the second pile 3b can be various shapes such as an ellipse, a triangle, a quadrangle, and a star, respectively. In addition, the cross-sectional shape of the pile 3 (or the yarn forming the same) means the shape of a cross section orthogonal to the extending direction of the pile 3 (or the yarn forming the same). Also, the difference in cross-sectional shape means not only that the types of figures such as an ellipse and a rectangle are different, but also that the types of figures themselves are the same but the sizes are different. For example, the cross-sectional shape of the first pile 3a is an ellipse having a width of 1 mm and a thickness of 250 μm (see FIG. 2A), and the cross-sectional shape of the second pile 3b is an ellipse having a width of 1 mm and a thickness of 100 μm. (See FIG. 2B). As another example, the cross-sectional shape of the first pile 3a may be an ellipse, and the cross-sectional shape of the second pile 3b may be a quadrangle. In any case, in the present embodiment, the first pile 3a has higher rigidity than the second pile 3b.

  In the present embodiment, W1> W2 when the lawn length of the first pile 3a is W1 and the lawn length of the second pile 3b is W2. Note that the piles 3a and 3b are inclined more or less on the base material 2 due to their own weight, trampling, etc., but the turf lengths W1 and W2 here are those when the piles 3a and 3b are linearly extended, respectively. It is the length, and is measured as the length from the surface of the substrate 2 to the tips of the piles 3a and 3b. The turf lengths W1 and W2 are expected to vary due to manufacturing errors. The turf length here is a nominal size that is also a design target value, for example, the same type of adjacent 30 pieces. It can measure as an average value of the pile 3 of.

  Further, W2 is preferably 5% or more shorter than W1, more preferably 6% or more, more preferably 7% or more, more preferably 8% or more, and more preferably 9% or less. More preferably, it is more preferably 10% or shorter. As described above, since the grass lengths W1 and W2 of the piles 3a and 3b included in the same artificial grass 1 are uneven, the artificial grass 1 is given a natural texture.

  The absolute amount of the turf lengths W1 and W2 is not particularly limited as long as W1> W2 is satisfied, but it can be relatively short as 20 mm ≦ W1 <50 mm (generally called a short pile), and 50 mm ≦ W1 ≦ 70 mm. It can also be relatively long (commonly called long pile).

  The filling amount of the filler 5 can be selected as appropriate, but when the height from the surface of the substrate 2 to the top of the filler layer formed by the filler 5 is H1, H1 ≧ (1/3 ) · W1 is preferable, and H1 ≧ (2/3) · W1 is more preferable. Further, it is preferable that H1 <(3/4) · W1. From the above viewpoint, (1/3) · W1 ≦ H1 <(3/4) · W1 is preferable, and (2/3) · W1 ≦ H1 <(3/4) · W1 is more preferable. preferable.

  As described above, in this embodiment, the turf leaves are reproduced by the piles 3a and 3b having different rigidity. More specifically, the second pile 3b has a shorter turf length and lower rigidity than the first pile 3a. . That is, since the second pile 3b having a lower rigidity and easily falling is formed shorter, the adjacent pile 3 is less likely to prevent the second pile 3b from overturning, and the second pile 3b is configured to fall more easily. Therefore, the second pile 3b becomes an “umbrella”, and scattering of the filler 5 can be suppressed. In addition, since the second pile 3b having a lower rigidity and easily falling down is formed shorter, there is less catch of spikes and the like on the falling second pile 3b, and the play performance of the artificial turf 1 can be maintained.

  As shown in FIG. 1, a plurality of piles 3 according to the present embodiment are planted at each planting point P <b> 1 on the base material 2 (eight in the example of FIG. 1). In particular, in the present embodiment, four first piles and four second piles are planted at the same planting point P1. However, the total number of piles 3 at the same planting point P1 and the numbers of the first pile and the second pile at the same planting point P1 can be changed as appropriate. Of course, the number of the first pile and the second pile at the same planting point P1 may be different.

<2. Manufacturing method>
Next, an example of a method for manufacturing the artificial turf 1 will be described. First, a resin material (hereinafter referred to as a first pile material) for forming the first pile 3a and a resin material (hereinafter referred to as a second pile material) for forming the second pile 3b are prepared. In the present embodiment in which the piles 3a and 3b are formed of the same material, only one type of material is prepared.

  Next, a first yarn for forming the first pile 3a is manufactured. Specifically, the first pile material is put into an extruder and melt extrusion molding is performed under a predetermined temperature condition. Thereby, the thread-like first pile material is extruded from the opening of the extruder. The temperature condition at this time can be a temperature higher than the melting point of the first pile material, for example, 230 ° C. Moreover, the opening of the extruder at this time has a shape corresponding to the cross-sectional shape of the first pile 3a, whereby the first yarn having the cross-sectional shape of the first pile 3a is formed (however, these are the same). The shape of the cross-sectional area is not exactly the same because it is deformed in the process such as stretching and thermal shrinkage described later). Subsequently, the thread-like first pile material extruded from the extruder is cooled and solidified in a water tank, and the thread is uniaxially stretched. As a method for uniaxial stretching, a roll stretching method can be used. Thereafter, the uniaxially stretched yarn, that is, the first yarn is wound around a bobbin. Hereinafter, the bobbin around which the first yarn is wound is referred to as a first bobbin.

  Subsequently, similarly, a second yarn for forming the second pile 3b is manufactured. Specifically, the second pile material is put into an extruder and melt extrusion molding is performed under a predetermined temperature condition. Thereby, the thread-like second pile material is extruded from the opening of the extruder. The temperature condition at this time can be a temperature higher than the melting point of the second pile material, for example, 230 ° C. Further, the opening of the extruder at this time has a shape different from that at the time of forming the first yarn, and has a shape corresponding to the cross-sectional shape of the second pile 3b. As a result, the second yarn having the cross-sectional shape of the second pile 3b is formed (however, since these cross-sectional shapes are deformed in the process of stretching, heat shrinking, etc., which will be described later, strictly the same. is not). Subsequently, the thread-like second pile material extruded from the extruder is cooled and solidified in a water tank, and this thread is uniaxially stretched. As a method for uniaxial stretching, a roll stretching method can be used. Thereafter, the uniaxially stretched yarn, that is, the second yarn is wound around a bobbin. Hereinafter, the bobbin around which the second yarn is wound is referred to as a second bobbin.

  Through the above steps, the first and second yarns having different cross-sectional shapes are formed. Thereafter, these yarns are annealed, and in this annealing step, thermal contraction of the first yarn and the second yarn proceeds. In the present embodiment, the annealing process is realized by leaving the first bobbin and the second bobbin in an oven heated to a predetermined temperature for a predetermined time. At this time, the annealing condition for the first yarn (hereinafter referred to as “first annealing condition”) and the annealing condition for the second yarn (hereinafter referred to as “second annealing condition”) are the same for the second yarn than for the first yarn after annealing. Is set so that the thermal contraction rate is increased, that is, the thermal contraction is likely to proceed in the further heating step thereafter. In the present embodiment, the first annealing condition and the second annealing condition are different from each other, and the first annealing condition is a condition in which annealing proceeds more easily than the second annealing condition. In order to achieve this, in the present embodiment, the annealing temperature for the first yarn is set higher than the annealing temperature for the second yarn, and the annealing time for the first yarn is set longer than the annealing time for the second yarn. . For example, the first bobbin can be left for 1 hour in an environment at 60 ° C., and the second bobbin can be left for 0.5 hour in an environment at 45 ° C. Note that the annealing temperature for the first yarn can be equal to or lower than the annealing temperature for the second yarn, and the annealing time for the first yarn can be equal to or lower than the annealing time for the second yarn. However, in this embodiment, the annealing condition is set so that the second yarn is more likely to be thermally contracted than the first yarn when further heat shrinkage is performed after annealing.

  Annealing is generally considered to have a function of relieving strain inside the yarn caused by molding or the like. Increasing the annealing temperature or increasing the annealing time tends to remove distortion more. For example, in the subsequent heating process such as the drying process of the backing agent, it is considered that heat shrinkage has occurred because the internal strain is eliminated by heat energy. The rate can be reduced.

  In the present embodiment, the first yarn and the second yarn having different rigidity and heat shrinkage rate are manufactured by the above process. More specifically, the second yarn is manufactured as a yarn having a higher heat shrinkage rate and lower rigidity than the first yarn. And after manufacture of such a 1st yarn and a 2nd yarn, the yarn fed out from the 1st bobbin and the 2nd bobbin by which these were wound up, respectively, was planted on substrate 2 using a tufting machine To do. In this embodiment, two first bobbins and two second bobbins are prepared, and a total of four yarns fed out from each are twisted into a bundle, and then the twisted yarns are reinforced by a tufting machine. Sew on material 2. At this time, the yarn penetrates the substrate 2 in the vertical direction, and the loop of the yarn protruding from the surface of the substrate 2 is cut at the center. As a result, from each planting point P1 on the base material 2, there are four turf leaves composed of the first pile 3a formed from the first yarn and a turf composed of the second pile 3b formed from the second yarn. A total of 8 turf leaves will stand, with 4 leaves. Hereinafter, the member formed of the base material 2 and the pile 3 formed so far is referred to as an intermediate 1a. The grass length W1 of the first pile 3a at the time of the intermediate 1a and the grass length W2 of the second pile 3b are the same except for a slight difference due to manufacturing errors (see FIG. 3A). ). Further, at this stage, the pile 3, particularly the second pile 3b, can fall to some extent due to its own weight, but for simplicity, FIG. 3 (a) shows a state in which the pile 3 is stretched. The same applies to FIG. 3B.

  Thereafter, in order to firmly fix the pile 3 to the base material 2, a backing agent is applied to the back surface of the base material 2 included in the intermediate body 1 a of the artificial turf 1. Subsequently, the intermediate 1a coated with the backing agent is placed in a high temperature environment to dry the backing agent. In addition, the high temperature environment here means that it is higher than normal temperature (25 ° C.), and is typically about 50 ° C. to 150 ° C. higher than normal temperature, for example, 90 ° C. In this drying step, the first pile 3a and the second pile 3b included in the intermediate 1a are thermally contracted, and both the turf lengths W1 and W2 are shortened (see FIG. 3B). However, since the thermal contraction rate of the second pile 3b is higher than the thermal contraction rate of the first pile 3a, W1> W2 after the thermal contraction in the drying process. When the backing agent is cured by this drying step and the backing layer 4 is formed, the final artificial turf 1 (excluding the filler 5) is manufactured.

<3. Modification>
As mentioned above, although one Embodiment of this invention was described, this invention is not limited to the said embodiment, A various change is possible unless it deviates from the meaning. For example, the following changes can be made. Moreover, the gist of the following modifications can be combined as appropriate.

<3-1>
In the above embodiment, two types of piles 3 are used. However, the artificial turf 1 can also be manufactured using three or more types of piles 3. In this case, it is only necessary that at least two types of piles 3 included in the artificial grass 1 finally obtained satisfy the same relationship as the above-described piles 3a and 3b.

<3-2>
In the above embodiment, the piles 3a and 3b have the same material, but have different cross-sectional shapes, so that the rigidity is different. However, the piles 3a and 3b may be made of different materials as long as the latter has lower rigidity than the former, and may have the same cross-sectional shape instead of or in addition to this.

<3-3>
In the above embodiment, the first yarn and the second yarn having different heat shrinkage rates are formed by changing the annealing conditions, and thus the piles 3a and 3b having different grass lengths W1 and W2 are formed. . However, the method for obtaining the piles 3a and 3b having different turf lengths W1 and W2 is not limited to this. For example, the heat shrinkage rate can be adjusted by appropriately adjusting the draw ratio when forming the first yarn and the second yarn. It is also possible to adjust the heat shrinkage rate by appropriately changing the material of the piles 3a and 3b. In addition, piles 3a and 3b having different turf lengths W1 and W2 can be formed without adjusting the heat shrinkage rate. For example, the yarn may be planted with respect to the base material 2 so that the turf length W2 of the pile 3b is shorter than the turf length W1 of the pile 3a.

<3-4>
In the above embodiment, annealing was performed after winding the yarn on a bobbin. However, after uniaxial stretching, the yarn may be annealed by passing it through a heating facility such as a hot water tank or hot air tank included in the same production line as the previous process, and then wound on a bobbin. . Thereby, artificial turf can be manufactured more efficiently.

Examples of the present invention will be described below, but the present invention is not limited to the following examples.
(Example)
In a monofilament molding line consisting of a φ30 mm single-screw extruder, polyethylene (Novatec LL (UF240) made by Nippon Polyethylene) is melt-spun at 230 ° C. to form yarn A and yarn B having the following cross-sectional shape to become turf leaves. did. These yarns A and B were cooled and solidified and uniaxially stretched in the same water tank as in the above embodiment. Yarn A and yarn B were wound on a bobbin and annealed in an oven. The annealing conditions were as follows.
Yarn A: The cross-sectional shape is an elliptical shape with a thickness of 250 μm and a width of 1 mm. Annealing conditions are 1 hour at 60 ° C.
Yarn B: The cross-sectional shape is an elliptical shape having a thickness of 100 μm and a width of 1 mm. Annealing conditions are 0.5 hours at 40 ° C.

Then, yarns A and B prepared as described above were planted by tufting on a base fabric made of polypropylene woven fabric. At this time, the yarns A and B were planted in units of six, three in total, and the planting pitch was adjusted to be 5 mm long and 2 cm wide. At this time, the turf length of yarns A and B immediately after tufting was set to 60 mm. Thereafter, 1000 g / m ² of SBR latex was applied to the back side of the intermediate body of artificial turf and dried in an oven at 90 ° C. for 30 minutes. Further, between the piles of the artificial turf thus obtained, a rubber chip filler was filled to a depth of 2 cm.

(Comparative Example 1)
An artificial turf similar to the above example was manufactured except that the yarn B was changed to the following yarn C, and was set as Comparative Example 1.
Yarn C: The cross-sectional shape is an elliptical shape having a thickness of 100 μm and a width of 1 mm. Annealing conditions are 1 hour at 60 ° C.

(Comparative Example 2)
An artificial turf similar to the above example was manufactured except that all the piles were formed of yarn A, and used as Comparative Example 2.

(Test method)
When the artificial turf of Example 1 and Comparative Examples 1 and 2 were measured for the difference in turf height, the difference in turf length, the scattering property of the filler, and the hook of the spike, the results shown in Table 1 were obtained. Obtained. Moreover, when the rigidity of yarn A-C was measured, the result as shown in Table 2 was obtained.

(Difference in turf height)
In order to measure a stable state, the height from the surface of the base fabric to the top of the pile was measured using a straight line made by Shinwa Measurement Co., Ltd. after 1 day from filling the artificial turf with a filler. . In addition, 30 piles are measured next to each pile type, and the average value of these measured values is taken as the turf height, and for artificial turf containing two types of piles, the difference in turf height between the two types of piles. Was calculated.

(Difference in turf length)
Using a straight scale manufactured by Shinwa Measurement Co., Ltd., the length from the surface of the base fabric to the top of the pile when the pile was stretched was measured. For each type of pile, 30 adjacent to each other are measured, and the average value of these measured values is the turf length. For artificial turf containing two types of piles, the difference in turf length between the two types of piles. Was calculated.

(Filling property of filler)
The soccer ball was allowed to freely fall on the artificial grass from a height of 2 m, and the maximum height of the scattered filler was measured. The maximum height was measured five times, and the average value of these was used as an index of the scattering property of the filler.

(Spike catch)
Wearing a spike for soccer (Tiempo Super Liguera 3 manufactured by NIKE), the resistance was determined by kicking the ball so that the spike bottom rubs against the ground. When it was possible to swing smoothly without being caught, the spike was caught “None”, and when even a slight resistance was felt, the spike was caught “Yes”.

(Pile stiffness)
Using a tensile tester manufactured by Shimadzu Corporation, the value of the test force (N) at 50% deformation was measured as the stiffness of the pile.

(Discussion)
As described above, in Example 1 using two types of piles having different rigidity and turf length, no spikes were caught and the scattering property of the filler was low. On the other hand, although the rigidity (cross-sectional shape) is different, in Comparative Example 1 using two types of piles having no difference in turf length, the scattering property of the filler is somewhat high, and there is also a catch of spikes. In Comparative Example 2 using one type of pile, the scattering property of the filler was extremely high. Therefore, the superiority of using piles having different rigidity and lawn length was confirmed.

DESCRIPTION OF SYMBOLS 1 Artificial grass 1a Intermediate body 2 Base material 3 Pile 3a First pile 3b Second pile 5 Filler W1 First pile grass length W2 Second pile grass length

Claims (8)

A substrate;
A large number of piles simulating turf leaves standing on the substrate;
A filler that is filled to form a filler layer between the multiple piles;
An artificial turf comprising
The multiple piles include two or more types of piles including a first pile and a second pile having different stiffnesses,
The second pile has a shorter turf length and lower rigidity than the first pile.
Artificial grass. The second pile is shorter than the first pile by 5% or more and the turf length is shorter.
The artificial turf according to claim 1. The first pile and the second pile have different cross-sectional shapes,
The artificial turf according to claim 1 or 2. A method for manufacturing artificial turf,
Producing two or more kinds of yarns including a first yarn and a second yarn having a higher heat shrinkage rate and lower rigidity than the first yarn; and
Two types of turf leaves including the first pile formed from the first yarn and the second pile formed from the second yarn by planting the two or more types of yarn on a base material Producing the artificial turf intermediate having a plurality of piles of the above piles;
Placing the intermediate in a high temperature environment and heat shrinking the pile;
including,
Artificial grass production method. The step of manufacturing the two or more types of yarns is performed under different conditions for the first yarn and the second yarn so that the thermal shrinkage rate of the second yarn is higher than the thermal shrinkage rate of the first yarn. Including the step of annealing at
The manufacturing method of the artificial turf of Claim 4. The annealing temperature for the first yarn is higher than the annealing temperature for the second yarn,
The manufacturing method of the artificial turf of Claim 5. The annealing time for the first yarn is longer than the annealing time for the second yarn,
The method for producing an artificial turf according to claim 5 or 6. The step of manufacturing the two or more types of yarns includes the step of forming the first yarn and the second yarn so that their cross-sectional shapes are different from each other.
The manufacturing method in any one of Claim 4 to 7.