Elastic Film Polymer Composition for Crack-Resistant Stretching
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Solution Overview
Problem
Existing elastic films used in laminates for disposable hygiene products face challenges in achieving a balance between good elastic behavior and processability, particularly under dynamic loads, leading to issues such as cracking and inefficient energy recovery during stretching.
Innovation Solution
The elastic film is composed of a polymer mixture with a high proportion of styrene block copolymer (28-60 wt.%) and polyolefin, minimizing residual components, resulting in improved elastic recovery and reduced cracking tendencies, with an elastic recovery value (ERV) of at least 0.4, allowing for efficient activation and bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the elastic film layer is made with high elastomer content to improve elastic behavior, then the elastic properties are enhanced, but the intrinsic strength decreases making the film more prone to cracking during processing
Solution Approach 1:
The patent applies parameter changes by precisely controlling the elastomer content within 10-40 wt% and the second polymer content within 60-90 wt%, optimizing the balance between elastic behavior and intrinsic strength. This quantitative parameter adjustment resolves the contradiction by finding the optimal composition range where both elastic properties and cracking resistance are satisfied
Solution Approach 2:
The patent uses composite materials by combining elastomer with a second polymer (such as polypropylene, polyethylene, or polyester) to create a polymer blend that exhibits both elastic behavior and sufficient intrinsic strength. The composite structure allows the elastomer to provide elasticity while the second polymer reinforces the film to prevent cracking during processing
2Stability of the object's composition
If the film is stretched to activate elastic behavior, then the elastic properties are revealed, but the cover layers thin and may fold or tear reducing reliability
Solution Approach 1:
The patent applies preliminary action by pre-stretching the elastic film in the machine direction during the manufacturing process before the cover layers are applied. This preliminary stretching activates the elastic behavior of the film in advance, allowing the cover layers to be applied to a pre-activated film structure, thereby avoiding the need to stretch the complete laminate later and preventing cover layer folding or tearing
Solution Approach 2:
The patent applies segmentation by separating the stretching operation from the laminate assembly process. The elastic film is stretched and activated as a separate component before being combined with cover layers, rather than stretching the complete laminate structure. This segmentation allows the film to be activated independently without subjecting the cover layers to excessive tension that would cause folding or tearing
3Ease of manufacture
If traditional polymer blends are used to balance elasticity and strength, then processing is improved, but energy recovery during stretching is inefficient reducing productivity
Solution Approach 1:
The patent applies parameter changes by optimizing the polymer composition parameters (elastomer 10-40 wt%, second polymer 60-90 wt%) to achieve a material that simultaneously provides good processability and high energy recovery efficiency. This parameter optimization resolves the contradiction by finding the composition range where both manufacturing ease and productivity are improved
Solution Approach 2:
The patent applies local quality by creating a polymer blend where different components serve specific functions: the elastomer provides elastic behavior and energy recovery, while the second polymer provides structural integrity and processability. This functional differentiation within the local composition allows the material to exhibit both easy processing and high energy recovery efficiency simultaneously
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 film exhibits enhanced elastic recovery and reduced cracking, enabling better fit and seal performance under dynamic conditions, with improved energy utilization and production efficiency.
Implementation Method 1
the elastic film layer (6) has an elastic recovery value (ERV), in particular an initial elastic recovery value, of at least 0.4
Implementation Method 2
This allows the formation of an elastic film characterized by a particularly low tendency to crack
Data Source
Figure 1
Figure 2A~2B
Figure 2C~2D
AI summary
The invention relates to an elastic film (3) with an elastic film layer (6) and at least one first non-elastic cover layer (4, 5) coextruded with the elastic film layer, wherein the elastic film layer (6) is formed from a polymer mixture with a first polymer component A and a second polymer component B, and wherein the first polymer component is a polyolefin or a polyolefin mixture. According to the invention, the second polymer component B is a styrene block copolymer, which is present in the polymer mixture in an amount between 28 wt.% and 60 wt.%, and wherein the polymer mixture contains less than 1 wt.% inorganic and less than 5 wt.% organic residual components.