Highly Filled Soft Polyolefin Compositions for Flame Retardancy
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Solution Overview
Problem
Existing polyolefin compositions with high amounts of inorganic fillers face challenges in maintaining flexibility and ductility while achieving self-extinguishing properties, often resulting in compromised mechanical properties and processing difficulties.
Innovation Solution
A polyolefin composition comprising 15-40% crystalline polymer fraction, 60-80% elastomeric fraction, and 40-80% inorganic filler, specifically designed to balance flexibility, ductility, and mechanical properties, with a broad molecular weight distribution and suitable intrinsic viscosity, allowing for high filler loading without deterioration of tensile strength and elongation at break.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If high amounts of inorganic fillers (65-70% by weight) are used to achieve self-extinguishing properties, then flame retardancy is improved, but physical-mechanical properties deteriorate (lower elongation at break, lower tensile strength, higher brittleness)
Solution Approach 1:
The patent changes the chemical composition parameters of the polymer matrix by using specific propylene copolymers with controlled comonomer content (5-15 mol% ethylene and/or alpha-olefin) and specific molecular weight characteristics (intrinsic viscosity 1.7-3.0 dl/g). This allows the matrix to maintain adequate mechanical properties while supporting high filler loads for flame retardancy.
Solution Approach 2:
The patent creates a composite material system consisting of a propylene-based polymer matrix combined with 40-65% by weight of inorganic filler (such as aluminum hydroxide, magnesium hydroxide, or calcium carbonate). The specific composition ratios and polymer characteristics enable the composite to achieve both flame retardancy and acceptable mechanical properties.
2Shape
If high amounts of inorganic fillers (40-65% by weight) are incorporated to improve physical properties such as soft touch and printability, then application-related physical properties are improved, but processing becomes difficult and mechanical properties deteriorate
Solution Approach 1:
The patent optimizes the polymer matrix parameters including intrinsic viscosity (1.7-3.0 dl/g) and comonomer content (5-15 mol%) to achieve a balance between flexibility and processability. This allows high filler loading for improved physical properties while maintaining adequate processing characteristics.
Solution Approach 2:
The patent applies filler particles with specific characteristics (such as coated inorganic fillers) to achieve local improvements in surface properties like soft touch and printability, while the bulk polymer matrix maintains the mechanical strength and processing properties needed for manufacturing.
3Stress or pressure
If flexural modulus and hardness are reduced to compete with plasticised PVC, then flexibility is improved, but mechanical strength and structural integrity may be compromised
Solution Approach 1:
The patent adjusts the polymer matrix composition by controlling the propylene copolymer characteristics (comonomer content of 5-15 mol%, intrinsic viscosity 1.7-3.0 dl/g) to achieve reduced flexural modulus and hardness values that provide flexibility comparable to plasticised PVC, while maintaining adequate mechanical strength through the optimized polymer-filler composite structure.
Data Source
AI summary
Flexible highly filled polyolefin compositions with improved balance of properties particularly for applications where softness and ductility at low temperature is requested comprising a soft heterophasic polyolefin composition the fraction soluble in xylene at 25°C of said polyolefin composition having IVgpc lower than 2.5 dl/g. Mw/Mn (GPC) equal to or higher than 4. Mz/Mw (GPC) equal to or higher than 2.5. Said polyolefin composition further comprising an inorganic filler (II) selected from flame-retardant inorganic fillers and inorganic oxides or salts and a further elastomeric polymer or polymer composition component (c) having flexural modulus (ISO 178) lower than 60 MPa, Shore A (ISO 868) lower than 90 and Tg (DMTA) lower than - 20°C.