Spray Dried Polyolefin Elastomer Powder for Rotational Molding
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Solution Overview
Problem
Current methods for producing textured polyolefin skins for automotive interiors face challenges such as deformation of patterns during vacuum forming, migration of plasticizers in PVC, and poor UV resistance in TPU, leading to issues like fogging, brittleness, and increased weight, which affect the quality and durability of interior components.
Innovation Solution
A process involving the melt blending of a polyolefin composition with an olefin block copolymer, a dispersing agent, and water to create an aqueous dispersion, which is then spray dried into a powdered composition and rotational molded into a skin with specific properties for improved scratch resistance, low temperature performance, and powder flow characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If positive vacuum forming is used to make textured olefinic thermoplastic elastomer skins, then the skin can be formed with texture, but the pattern deformation occurs during forming resulting in inferior texture retention
Solution Approach 1:
The patent changes the physical-chemical parameters of the polymer material by using olefin block copolymer with specific molecular architecture (hard and soft segments) instead of conventional olefinic thermoplastic elastomers. This parameter change enables the material to maintain texture integrity during vacuum forming while still allowing formability, resolving the contradiction between shape retention and manufacturing precision.
2Shape
If PVC is used for interior skins, then good formability and texture retention are achieved, but plasticizer migration and volatilization occur leading to physical property changes and fogging
Solution Approach 1:
The patent fundamentally changes the material composition by replacing PVC with olefin block copolymer, eliminating the need for plasticizers entirely. This parameter change in material chemistry resolves the harmful plasticizer migration and volatilization issues while maintaining the desired formability through the copolymer's inherent molecular structure with hard and soft segments.
Solution Approach 2:
The olefin block copolymer acts as a composite material system with distinct hard segments providing structural integrity and soft segments providing flexibility and formability. This composite structure at the molecular level achieves the formability previously requiring plasticizers in PVC, without the associated harmful migration effects.
3Shape
If PVC is used for interior skins, then good texture retention is achieved, but the weight increases and gas efficiency decreases
Solution Approach 1:
The patent changes the material parameter from PVC to olefin block copolymer, which has inherently lower density. This parameter change reduces the weight of interior skins while maintaining texture retention capabilities through the copolymer's molecular structure, thereby improving gas efficiency without sacrificing formability or texture integrity.
4Stability of the object's composition
If TPO is used for slush molding, then good ductility is achieved, but poor powder flow characteristics and difficulty in pulverization occur
Solution Approach 1:
The patent changes the molecular architecture parameter from conventional TPO to olefin block copolymer with specific hard and soft segment distribution. This parameter change enables the material to maintain ductility while significantly improving powder flow characteristics and pulverization ease, as the block copolymer structure creates more favorable powder handling properties for slush molding processes.
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 process results in a skin with enhanced scratch and mar resistance, improved low temperature properties, and better powder flow, addressing the limitations of existing materials like PVC and TPU, while maintaining design flexibility and reducing weight and emissions.
Implementation Method 1
spray drying said dispersion forming a powdered polyolefin composition having an average particle size equal to or less than 250 microns
Implementation Method 2
the free-flowing polymer powder contacts the hot mold where the powder melts and flows over the mold
Data Source
AI summary
The present invention provides a method comprising rotational molding a powdered polyolefin elastomer composition to form a skin, the composition formed by spray drying an aqueous polyolefin dispersion composition which is itself formed by melt blending a polyolefin composition comprising an olefin block copolymer, a dispersing agent, and water, wherein said aqueous dispersion preferably has a pH less than 12.