Silane Cross-Linkable Polyolefin for Vacuum Formed Textured Skin
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Solution Overview
Problem
Textured skin made of olefinic thermoplastic elastomers suffers from pattern deformation during vacuum forming, leading to inferior grain retention, and existing solutions like peroxide treatment and electron beam cure are either difficult to control or expensive.
Innovation Solution
A cross-linkable polyolefin composition comprising 60-75 weight percent silane cross-linkable polyolefin polymer, a moisture-cure condensation catalyst, and 25-40 weight percent low-density polyolefin polymer elastomer, prepared with a metallocene catalyst, which is extruded into a sheet, textured, and then thermoformed or vacuum formed to retain texture effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If positive vacuum forming is used to create textured skin, then the forming process can be completed, but the texture pattern deforms and grain retention becomes inferior
Solution Approach 1:
The polyolefin elastomer is pre-crosslinked before the vacuum forming process to stabilize the texture pattern. The crosslinking is performed by adding a crosslinking agent and curing the material prior to forming, which prevents pattern deformation during the subsequent vacuum forming operation while maintaining good grain retention.
2Manufacturing precision
If peroxide treatment and dynamic heat treatment are applied to increase blend viscosity, then grain retention improves, but the process becomes difficult to control due to uncontrolled radical reactions
Solution Approach 1:
The invention changes the crosslinking mechanism from uncontrolled radical reactions to controlled cationic polymerization. By using a cationic polymerization initiator instead of peroxide treatment, the crosslinking process becomes more controllable and predictable, while still achieving the desired increase in blend viscosity and grain retention.
3Manufacturing precision
If elastomer cross-linking is performed to improve grain retention, then texture retention improves, but thermoforming capability is impaired
Solution Approach 1:
The invention performs crosslinking after the vacuum forming process rather than before. The formed skin is then subjected to moisture and heat treatment to induce crosslinking. This sequence allows the material to be thermoformed first, and then crosslinked to improve grain retention, thereby avoiding the impairment of thermoforming capability.
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 provides improved grain retention and mechanical properties, allowing for effective thermoforming while maintaining texture integrity, and is more accessible and cost-effective than previous methods.
Implementation Method 1
a moisture-cure condensation catalyst
Implementation Method 2
cross-linkable polyolefin composition
Data Source
AI summary
The present invention relates to a flexible polyolefin composition, a sheet made therefrom, and a formed textured skin for applications such as interior furnishings of an automobile and a process to make such composition, sheet, and textured skin. Specifically said composition comprises an extrudable cross-linkable polyolefin composition comprising: (i) from 60 to 75 weight percent of one or more one silane cross-linkable polyolefin polymer; (ii) a moisture-cure condensation catalyst; and (iii) from 25 to 40 weight percent of one or more polyolefin polymer elastomer. Preferably an extruded sheet of said composition is formed into a textured skin, preferably by positive vacuum forming.