Abstract:
A tufted artificial turf having a flexible, water-permeable support fabric provided with tufts is disclosed. The tufts include parts of straight monofilament yarn and parts of curly monofilament yarn and are manufactured from a compound yarn formed by twining together the straight monofilament yarn with the curly monofilament yarn.

Description:
RELATED APPLICATIONS 
       [0001]    This application claims priority to BE 2007/0050 filed Feb. 7, 2007. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention pertains to an artificial turf and to the yarns required therefore. The object of the present invention is to provide a new type of artificial turf comprising a combination of straight and curly monofilament yarns. The thus obtained artificial turf provides, on the one hand, the look of natural grass, and on the other hand, the known use of a well-known infill layer by filling for example sand and/or rubber particles for enhancing the elasticity of the surface of the artificial turf becomes superfluous. 
         [0004]    2. Description of the Related Art 
         [0005]    Many patent applications describe yarns for the manufacture of synthetic turfs made of a variety of materials and combinations thereof. Often, combinations are presented of polyethylene, polypropylene, or block copolymers thereof. Further to the use of these materials, the use of polyamide 6 (nylon) is also known, for instance from the Japanese patent application JP-A-3.279.419. 
         [0006]    Apart from the choice of material, many structural shapes of yarns are known, among others straight monofill, fibrillated or monofill curled yarns. 
       SUMMARY OF THE INVENTION 
       [0007]    The present invention provides a specific combination of structural shape and material for the yarns as a result of which tufts are formed which do not need infill material. Therefore, especially the application and the maintenance of such synthetic turfs is simplified. Also, recycling possibilities are strongly increased as a result of which these synthetic turfs are more environment-friendly. 
         [0008]    The present invention is related to yarns, tufted on a carrier material. It is generally known that several yarns twisted or twined together are tufted in a carrier material. In this way standing tufts are formed, wherein each individual tuft is composed of a multiple of filaments. 
         [0009]    The invention relates mainly to a tufted artificial turf comprising a flexible, water-permeable support fabric, provided with tufts, wherein each tuft comprises partly of straight monofilament yarn and partly of curly monofilament yarn, characterised in that said tufts are manufactured from a compound yarn composed from said straight monofilament yarn twined together with the curly monofilament yarn. 
         [0010]    According to the invention the support fabric comprises a flexible way water-permeable plastic material, preferably a laminate of a UV-stabilised tuft fabric from polypropylene, provided with a latex backing. The specific weight of this laminate amounts preferably between 800 and 1500 g/m 2 , and more preferably between 1100 and 1400 g/m 2 . 
         [0011]    The artificial turf according to the invention comprises tufts, manufactured from a compound yarn, i.e. from straight monofilament yarn and curly monofilament yarn, wherein the straight and curly monofilament yarns are twined together such that the curly monofilament yarn is nested around the straight monofilament yarn, wherein the curly monofilament yarn provides partly stability and partly elasticity to the straight monofilament yarn. Because of this, an infill with for example sand or rubber particles is superfluous. 
         [0012]    In a preferred embodiment of the artificial turf according to the invention, the curly and straight monofilament yarns of said composed yarn are extruded from polyamide, for example polyamide 6, polyamide 6.6 and polyamide 6.12, and more preferably polyamide 6. 
         [0013]    In a further preferred embodiment, both the straight monofilament yarn and the curly monofilament yarn of said composed yarn each comprise preferably of 4 to 12 individual filaments, more preferably of 6 to 10 individual filaments, and most preferably of 8 individual filaments. 
         [0014]    The thickness and width of the filaments are such that they resemble individual blades of grass; the width of the individual filaments preferably ranges between 0.5 and 2 millimetre, more preferably between 0.75 and 1.5 millimetre, and is most preferably equal to approximately 0.9 millimetre. 
         [0015]    The thickness of the individual filaments is not only important to achieve the look of natural grass, but also to achieve the desired properties of elasticity. The individual filaments usually have a thickness between 50 μm and 200 μm, more preferably between 100 μm and 150 μm and most preferably, it amount to approximately 140 μm. 
         [0016]    The yarn number of the individual filaments of the straight monofilament yarn usually ranges between 500 and 2000 dtex, more preferably between 750 and 1500 dtex, and is most preferably equal to approximately 1000 dtex. Whereas the yarn number of the individual filaments of the curly monofilament yarn usually ranges between 300 and 1500 dtex, more preferably between 500 and 1000 dtex, and most preferably is equal to approximately 750 dtex. The total dtex value per tuft preferably ranges between 12,000 and 16,000, and more preferably between approximately 13,000 and 15,000, and is most preferably equal to approximately 14,000 dtex. 
         [0017]    In a further preferred embodiment of the invention, the individual filaments are manufactured in several shades, wherein the straight monofilament yarn preferably comprises 2 to 6 dark green and 2 to 6 olive green filaments, more preferably 3 to 5 dark green and 3 to 5 olive green, and most preferably 4 dark green and 4 olive green filaments. The curly monofilament yarn preferably comprises 1 to 3 beige and 3 to 9 light green filaments, more preferably 1.5 to 4.5 beige and 2.5 to 7.5 light green, and most preferably 2 beige and 6 light green filaments. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0018]    The curly monofilament yarn is generally manufactured from a straight monofilament yarn that is subjected to one or more heat treatments. This treatment may take place as from the extrusion of the yarn and/or during the processing step and/or on the finished carpet. Preferably, the final curling and crimping is obtained after a heat treatment during the coating of the tuft fabric with a stabilizing agent, such as for example latex, as a result of which also the tufts become firmly attached in the tuft fabric. In its finished form the support fabric comprises a laminate of a tuft fabric with an additional layer of a stabilizing agent, preferably a latex, applied onto it. 
         [0019]    According to present the invention, the manufacturing of curly monofilament yarn by means of a heat treatment can be performed in 3 different ways, i.e. by means of a heat treatment of the monofilament yarn directly after extrusion and before the tufting process, by means of a heat treatment during the application of the adhesion material (latex) on the tuft fabric, or by means of a combination of both aforementioned heat treatments. In a preferred embodiment the straight monofilament yarn is subjected to a first heat treatment which takes place before the tufting process such that an initial curling arises. Subsequently, the straight and partly curly monofilament yarn is tufted in line on a tuft fabric, after which a latex backing is applied to the back of aforementioned tuft fabric by means of a second heat treatment. The application of the latex backing and the associated heat treatment completes on the one hand the curling and ensures on the other hand an optimum fixing of the tufts in the tuft fabric. After aforementioned heat treatment(s), the curly monofilament has a shrinkage of at least 60% and more preferably of at least 50%. Therefore, the rest height of the curly yarn ranges between ⅕ to ⅗, preferably ⅓ to ⅗ and most preferably approximately ½ of the length of the straight monofilament yarn in the tuft. This height ratio on the support fabric ensures that a good elasticity and bonding strength to the artificial turf are obtained such that an infill becomes superfluous. 
         [0020]    Both aforementioned monofilament yarns are subsequently twined together to form one yarn and this with a speed of approximately 30 turns per running meter wherein the curly monofilament yarn is nested around the straight monofilament yarn. The finally obtained composed yarn has a yarn number which usually ranges between 10,000 dtex and 20,000 dtex, preferably between 12,000 and 16,000, more preferably between 13,000 and 15,000 and is most preferably approximately 14,000 dtex. 
         [0021]    Preferably, the filaments in a tuft all have the same length between 3 and 5 cm, more preferably between 3.5 cm and 4.5 cm and most preferably approximately between 3.7 and 3.9 cm. The curly filaments in their curly state have a length ranging between 40 and 60% with respect to the initial length. In general, the shrinkage is obtained by a heat treatment. 
         [0022]    The invention is further illustrated by means of the examples below which illustrate some preferred embodiments of the invention. 
       Example 1 
       [0023]    The compound yarn comprises 8 filaments curly monofilament yarn of polyamide 6 (nylon) with a compound dtex value of 6000 (8 filaments of each 750 dtex per filament) with a width of 0.9 mm, a thickness of 140 μm and a height of 38 mm in elongated form and a height of approximately 24 mm in curly form with 8 filaments straight monofilament (diamond structure) with a dtex value of 8000, a width of 0.9 mm and also a thickness of 140 μm. These yarns are twined together and subsequently this composed yarn is linearly tufted with approximately 140 stitches per running meter with a needle distance of 5/16″, and a pile height of 38 mm such that a pile weight was obtained of approximately 2200 g/m 2 . The support material comprises a polypropylene tuft fabric which is UV-stabilised with a specific weight of approximately 164 g/m 2  provided with a latex backing with 1000 g/m 2 . 
         [0024]    The obtained artificial turf have the following properties: 
         [0000]    
       
         
               
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 Colour stability 
                 Scale 7 (DIN 54004) 
               
               
                   
                 UV-Stability 
                 &gt;6,000 u (DIN 53387) 
               
               
                   
                 Water permeability 
                 6.10 −4  m/sec 
               
               
                   
                 Flame retardancy 
                 Class 1 (DIN 51960) 
               
               
                   
                 Pile anchoring 
                 &gt;30 N 
               
               
                   
                 Chlorine resistance 
                 4-5 (DIN 54019) 
               
               
                   
                 Resistance to seawater 
                 4-5 (DIN 54007) 
               
               
                   
                   
               
             
          
         
       
     
       Example 2 
       [0025]    In a similar manner a number of other artificial turfs were tufted. Table I below gives the individual data for each type of filament. 
         [0000]    
       
         
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
             
           
               
                   
                   
               
               
                   
                 Ex 2 
                 Ex 3 
                 Ex 4 
                 Ex 5 
                 Ex 6 
                 Ex 7 
                 Ex 8 
                 Ex 9 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 Curly PA monofilament 
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 number 
                 8 
                 10 
                 6 
                 6 
                 6 
                 4 
                 8 
                 8 
               
               
                 dtex (per fil) 
                 740 
                 600 
                 1300 
                 1100 
                 1200 
                 1500 
                 800 
                 750 
               
               
                 length straight (mm) 
                 40 
                 42 
                 38 
                 39 
                 45 
                 40 
                 38 
                 46 
               
               
                 length (curly) 
                 25 
                 20 
                 18 
                 17 
                 21 
                 16 
                 15 
                 19 
               
               
                 width (mm) 
                 0.6 
                 0.8 
                 1.4 
                 0.9 
                 1 
                 0.95 
                 0.85 
                 0.6 
               
               
                 thickness (μm) 
                 150 
                 85 
                 100 
                 140 
                 130 
                 175 
                 100 
                 140 
               
               
                 Straight PA monofilament 
               
               
                 number 
                 8 
                 6 
                 10 
                 8 
                 12 
                 12 
                 10 
                 8 
               
               
                 dtex (by fil) 
                 1000 
                 1200 
                 600 
                 1500 
                 1100 
                 1000 
                 1300 
                 1200 
               
               
                 length 
                 40 
                 42 
                 38 
                 42 
                 48 
                 38 
                 38 
                 46 
               
               
                 width (mm) 
                 0.8 
                 0.9 
                 0.5 
                 1 
                 0.9 
                 0.8 
                 1 
                 0.7 
               
               
                 thickness (μm) 
                 140 
                 140 
                 150 
                 170 
                 130 
                 135 
                 140 
                 180 
               
               
                   
               
             
          
         
       
     
         [0026]    The thus obtained composed yarns are tufted on a tuft fabric and provided with a water permeable backing, for example made of latex. 
         [0027]    It will be understood by those of skill in the art that numerous and various modifications can be made without departing from the spirit of the present invention. Therefore, it should be clearly understood that the forms of the present invention are illustrative only and are not intended to limit the scope of the present invention.