Elastomeric Multilayer Film with Antiblock Skin
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Solution Overview
Problem
Existing polyolefin-based elastic film structures and laminates for hygiene and medical products face challenges such as tackiness leading to blocking issues, high costs, and environmental impacts, along with limited processability and mechanical performance due to the use of styrenic block copolymers and other materials.
Innovation Solution
The development of stretch-modified elastomeric multilayer films comprising a core layer of ethylene-α-olefin block copolymer and outer layers with antiblock agents, which undergo a specific stretch process to enhance elasticity and reduce blocking, while maintaining mechanical properties and environmental sustainability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If elastic films are made from styrenic block copolymers (SBCs) to achieve excellent elasticity and flexibility, then physical properties are improved, but cost increases and thermal stability deteriorates
Solution Approach 1:
The patent changes the material parameters by selecting ethylene-α-olefin block copolymers with specific density ranges (0.895-0.925 g/cc for core layer, 0.910-0.940 g/cc for skin layer) and melt flow indices, thereby achieving the desired elasticity without the thermal degradation issues of SBCs
Solution Approach 2:
The patent uses a composite multilayer structure combining core layer and skin layer materials with different properties. The core layer provides elasticity while the skin layer with higher crystallinity provides thermal stability and reduced blocking, creating a synergistic composite material system
2Reliability
If polyolefin elastomers are used to improve thermal stability and reduce environmental impact, then thermal stability and environmental sustainability are improved, but physical properties deteriorate
Solution Approach 1:
The patent creates a composite multilayer film where the core layer uses polyolefin elastomer for thermal stability and environmental sustainability, while the skin layer uses higher crystallinity material to compensate and enhance physical properties, achieving both goals simultaneously
Solution Approach 2:
The patent applies different material qualities to different parts of the film: the core layer is optimized for elasticity and thermal stability, while the skin layer is optimized for physical strength and blocking resistance, allowing each region to excel at its specific function
3Ease of manufacture
If coextrusion of low crystallinity elastic core with high crystallinity skin materials is used to reduce blocking and improve machinability, then blocking is reduced and machinability is improved, but elasticity deteriorates
Solution Approach 1:
The patent carefully controls the crystallinity parameter of the skin layer material and its thickness ratio to ensure that while blocking and machinability are improved, the elasticity provided by the core layer is not compromised
Solution Approach 2:
The patent designs a composite structure where the high crystallinity skin layer provides blocking resistance and machinability, while the low crystallinity elastic core layer maintains elasticity, creating a balanced composite material system
4Strength
If elastomer films are laminated to nonwoven substrate and stretched to activate non-woven for elasticity, then elasticity is improved, but blocking and handling issues worsen
Solution Approach 1:
The patent segments the film into distinct core and skin layers with different functions, eliminating the need for lamination with nonwoven substrates and subsequent stretching processes that cause blocking
Solution Approach 2:
The patent creates an integrated composite elastomeric film where elasticity is inherent in the core layer material composition and structure, eliminating the need for post-manufacturing stretching processes that generate blocking issues
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 solution minimizes film blocking, improves handling and machinability, and reduces permanent set and retraction forces, resulting in enhanced elastic performance and reduced environmental impact.
Implementation Method 1
performing a first stretch of the film in at least one direction to a draw ratio of at least 1.9
Implementation Method 2
performing a first stretch of the film in at least one direction to a draw ratio of at least 1.9 to form a stretch-modified multilayer film
Implementation Method 3
subsequently relaxing the stretch-modified multilayer film in the at least one direction
Data Source
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AI summary
A stretch-modified elastomeric multilayer film comprising a core layer comprising a first ethylene-α-olefin block copolymer, wherein the first ethylene-α-olefin block copolymer comprises at least 50 mol.% ethylene, has a melt index (I2) from 0.5 g/10 min to 5 g/10 min, and has a density of 0.850 g/cc to 0.890 g/cc, and at least one outer layer independently comprising a second ethylene-α-olefin block copolymer and from 2.5 to 30 wt.% of an antiblock agent, wherein the second ethylene-α-olefin block copolymer comprises at least 50 mol.% ethylene, has a melt index (I2) from 0.5 g/10 min to 25 g/10 min, and has a density of 0.850 g/cc to 0.890 g/cc, wherein the density of the first ethylene-α-olefin block copolymer is equal to or greater than the density of the second ethylene-α-olefin block copolymer.