Raw materials
YARN
From granule to tape:
Colouring, ultraviolet inhibitors and other ingredients are added to the opaque polymer granules to form the master batch. The colouring agent can be green, blue, white etc; according to the desired end use. The ultraviolet inhibitors are designed to withstand the harsh Australian climatic conditions.
The PP/PE granules and master batch are melted in separate extruders, mixed together in liquid form and forced under pressure through a slit die.
From tape to yarn:
The mix emerges from the die as a molten sheet, which solidifies upon contact with a chilled roller.
The solidified sheet is then cut into discrete tape widths, depending on the denier (tex) of the finished product.
The tape is re-heated in an oven to its softening point and stretched between rollers. This has the effect of exciting the molecules within the tape and aligning them in a straight line.
The resultant tape has now been drawn down in size and is dramatically thinner and narrower than before.
The drawn tape is passed over a fibrillator to impart a mesh like appearance. This will later aid its conversion into a sports surface and duplicate the appearance of real grass.
The final stage in this process is to twist the slit, drawn and fibrillated tape into a yarn. The twist provides body and bulk to the yarn; this can be seen once it has been tufted into a sports surface.
For certain sports like bowls and hockey, the yarn is further processed using heat treatment to set the yarn in a non-directional manner. This process is called knit-de-knit.
POLYBACK
The quality of the backing is essential for the quality of the carpet. T.E.A.M. only uses backing materials that are resistant against weather influences such as UV light, moisture and warm/cold conditions. Being part of sport fields, the outdoor backing passes through a number of important stages. At each stage the most important features are highlighted:
1. TUFTING
- Strength (stretch and pull)
- Pile position
- Pile fixation (tuft lock)
- Back stitch
2. COATING
- Adhesion of latex to the backing
- Form stability
- Heat stability until ±110°C = cure temperature latex compound
- Good roll-up conditions up to and including 75 linear metres (no folds)
- Straight winding with correct machinery equipment
3. APPLICATION
- Can be rolled out well and straight ahead
- Can be glued well
- Can be cut well, for the lining
- Minimal or no fraying (fleeced backing)
4. UTILISATION IN THE SYSTEM
- Not sensitive to fluctuations in weather conditions
- Moist and rot resistant
- UV-resistant
- Remains flat
No wearing out, caused by usage with softer unbound, substructure systems (place stable)
LATEX
Latex in the liquid form is a polymer dispersion made up of small spherical particles finely divided in water. The polymers are long chained Carbon molecules made up from various Monomers available.
Synthetic grass utilises Carboxylated Styrene-Butadiene-Co-polymer as the latex in the backing compound. The choice is due to the physical attributes the Monomers impart to the latex combined with considerations.
A lick roller system is used for the application of the latex compound to the back of the synthetic grass.
Drying is a critical operation for the final quality of the product. It is during this process that the latex will crosslink giving the final product increased strength and water resistance. For cross linking to take place at any meaningful rate the latex on the synthetic grass must be thoroughly dried and then held at a temperature over 100 degC for a time determinate on the temperature achieved.
Tuft lock can be affected by a number of different variables including; the degree of cross linking, percentage of filler loading of the compound, the application weight of latex compound, the degree of penetration of the latex and the amount of yarn lubricant are among the most important.
