Propylene Copolymer Composition for Low Fogging Roofing
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Solution Overview
Problem
Existing thermoplastic polymer compositions used for upholstery and single-ply roofing applications lack sufficient softness and sealing properties, with issues such as oligomer migration leading to fogging, high VOC values, and impaired adhesion and sealing.
Innovation Solution
A propylene copolymer composition comprising 50.0 to 95.0 wt% of a heterophasic propylene copolymer with a propylene random copolymer matrix phase, and 5.0 to 25.0 wt% of a propylene-based plastomer, which provides a low tensile modulus and improved softness for these applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If Ziegler-Natta catalysed polypropylene resins are used, then high melting temperature and low tensile modulus are achieved, but high oligomer content causes fogging and high VOC values
Solution Approach 1:
The patent changes the catalyst type from Ziegler-Natta to metallocene catalyst, which fundamentally alters the polymerization parameters and produces a different polymer structure with lower oligomer content while maintaining the desired low tensile modulus and high melting temperature characteristics
Solution Approach 2:
The patent uses a composite approach by combining metallocene catalysed polypropylene resin with specific additives and potentially other polymers to achieve the desired balance of properties - low tensile modulus for softness, high melting temperature, and low oligomer content to minimize fogging and VOC emissions
2Object-generated harmful factors
If metallocene catalysed polypropylene resins are used, then low oligomer migration and low fogging are achieved, but low melting temperature and poor sealing behaviour occur
Solution Approach 1:
The patent adjusts the metallocene catalyst parameters and polymerization conditions to produce a resin with optimized molecular weight distribution and crystallinity, thereby increasing the melting temperature while preserving the low oligomer migration and fogging benefits
Solution Approach 2:
The patent creates a composite material system using metallocene catalysed polypropylene as the base resin and incorporates specific additives or co-polymers that enhance sealing behavior and increase melting temperature while maintaining the low oligomer content advantage
3Strength
If RAHECOs with low stiffness are used, then low tensile modulus is achieved, but oligomer migration causes fogging and impairs adhesion and sealing properties
Solution Approach 1:
The patent modifies the RAHECO composition parameters, specifically the ratio of crystalline to amorphous phases and the molecular weight distribution, to reduce oligomer migration while maintaining the low tensile modulus necessary for softness and flexibility
Solution Approach 2:
The patent develops a composite material combining RAHECO with specific additives and potentially other polymers that prevent oligomer migration and improve adhesion and sealing properties while preserving the low stiffness characteristic
4Strength
If ethylene based plastomers are added to RAHECOs, then impact properties are improved, but sealing performance does not improve and oligomer migration is not sufficiently reduced
Solution Approach 1:
The patent optimizes the composition parameters of the blend, specifically the ratio of RAHECO to plastomer and the molecular weight distribution of the components, to achieve synergistic effects that simultaneously improve impact resistance and sealing properties while reducing oligomer migration
Solution Approach 2:
The patent creates an optimized composite material system combining RAHECO with specific types and amounts of plastomers, potentially adding other components, to achieve the desired balance of impact properties, sealing behavior, and reduced oligomer migration
Data Source
AI summary
The present invention relates to a propylene copolymer composition comprising (A) from 50.0 to 95.0 wt %, based on the total amount of the propylene copolymer composition, of a heterophasic propylene copolymer having a matrix phase and an elastomeric phase dispersed in said matrix phase, wherein the matrix phase is a propylene random copolymer, the heterophasic propylene copolymer further having a melt flow rate MFR2 of 0.2 to 12.0 g/10 min, determined according to ISO 1133 at a temperature of 230° C. and a load of 2.16 kg, and a xylene cold solubles (XCS) fraction in the range of from 20.0 to 50.0 wt % based on the total amount of the heterophasic propylene copolymer (A), determined according to ISO 16152 at a temperature of 25° C., and (B) from 5.0 to 25.0 wt %, based on the total amount of the propylene copolymer composition, of a propylene based plastomer having a density in the range of from 845 to 870 kg/m3, determined according to ASTM D 1505 on compression moulded test specimens and a melt flow rate MFR2 of 1.0 to 30.0 g/10 min, determined according to ASTM D1238 at a temperature of 230° C. and a load of 2.16 kg, wherein the propylene copolymer composition has a tensile modulus of below 300 MPa, determined according to ISO 527-2, measured on injection moulded test specimens, and follows the following inequation: tensile modulus [MPa]<375 MPa−6×amount of (B) [MPa×wt %/wt %], an article comprising said propylene copolymer composition and the use of said propylene copolymer composition in a single ply roofing membrane.