Artificial grass
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Solution Overview
Problem
Current polyethylene materials used in artificial grass applications lack sufficient thermal stability, durability, and ball roll resistance while maintaining softness and durability, which are essential for high-performance sports surfaces.
Innovation Solution
Polyethylenes catalyzed using bis-tetrahydroindenyl or bisindenyl metallocene catalysts with specific density and melt index ranges, exhibiting long chain branching and improved rheological properties, are used to produce slit films and monofilaments with enhanced thermal and mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If metallocene catalysed polyethylenes with narrow MWD and narrow SCBD are used, then uniform molecular structure and enhanced certain properties are achieved, but thermal stability and ball roll resistance are insufficient
Solution Approach 1:
The patent changes the molecular weight distribution parameter from narrow to broad (Mw/Mn ratio of 10-50) and introduces long chain branching (LCB) to achieve both thermal stability and molecular structure control. This parameter change resolves the contradiction by allowing high Vicat Softening Temperature while maintaining processability.
Solution Approach 2:
The patent creates a composite molecular architecture combining broad MWD characteristics with long chain branching structures. This composite approach integrates the thermal stability benefits of LCB with the processability advantages of broad MWD, achieving both high temperature resistance and good forming properties.
2Shape
If monofilaments with sharp edges (double diamond, C-shaped, elliptical) are used, then area optimization is achieved, but weakness points creating splitting occur
Solution Approach 1:
The patent moves away from highly symmetric sharp-edged geometries (double diamond, elliptical) toward asymmetric rounded designs that eliminate stress concentration points. The rounded monofilament shapes distribute mechanical stresses more evenly, preventing splitting while maintaining area optimization.
Solution Approach 2:
The patent applies spheroidality by using rounded monofilament shapes instead of sharp-edged geometries. The curved surfaces eliminate weakness points where splitting would initiate, while the overall shape is optimized to maintain sufficient cross-sectional area for structural integrity.
3Object-affected harmful factors
If polyethylene materials are used to achieve softness, then injury prevention is improved, but durability and ball roll resistance deteriorate
Solution Approach 1:
The patent changes the density parameter to a specific range (0.910-0.940 g/cm³) and introduces long chain branching to achieve the optimal balance between softness and durability. These parameter changes allow the material to provide injury prevention through softness while simultaneously achieving high durability and ball roll resistance.
Solution Approach 2:
The patent creates a composite polyethylene structure with long chain branching that combines the softness characteristics needed for injury prevention with the mechanical strength required for durability. The LCB structure provides both the cushioning effect for safety and the structural integrity for long-term reliability.
4Object-affected harmful factors
If conventional Ziegler-Natta copolymers are used, then softness is achieved, but thermal stability and Vicat Softening Temperature are insufficient
Solution Approach 1:
The patent changes the molecular architecture by introducing long chain branching and adjusting the density to 0.910-0.940 g/cm³. These parameter changes enable the polyethylene to maintain softness for injury prevention while achieving significantly higher thermal stability and Vicat Softening Temperature compared to conventional Ziegler-Natta copolymers.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The resulting polyethylene materials demonstrate improved tensile properties, higher Vicat Softening Temperature, and better ball roll resistance, ensuring longer durability and softer feel for artificial grass applications.
Implementation Method 1
a polyethylene prepared with a bistetrahydroindenyl or bisindenyl metallocene catalyst complex
Data Source
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AI summary
Artificial grass tufted from slit film or monofilaments prepared with a polyethylene prepared with a bistetrahydroindenyl or bisindenyl metallocene catalyst complex having (a) a density in the range of 0.910 to 0.937 g/cm3 as determined by ISO 1183 at a temperature of 23° C and (b) a melt index MI2 in the range of 0.5 to 5 g/10 min as determined by ISO 1133/D at a temperature of 190° C and at a load of 2.16 kg, wherein said polyethylene has a grheo of less than 0.9 or an LCBI of greater than 0.08, and the polyethylene has a Vicat Softening Temperature Tv according to the following equation: Tv > 41234 d2 + 77500 d - 36295 wherein Tv is the Vicat Softening Temperature in °C and d is the density of the polyethylene in g/cm3.