Multilayer Film Cling Layer Composition
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Solution Overview
Problem
Multilayer films with cling properties face issues such as noise during unwinding, contamination, and two-sided cling due to additives like polyisobutylene, and high costs and processing difficulties with polyethylene elastomers at high levels.
Innovation Solution
A multilayer film composition incorporating a cling layer with a blend of polyethylene elastomer and ultra-low or very low density polyethylene polymer, both with a purge fraction greater than 20% as determined by Crystallization Elution Fractionation, reducing the need for expensive polyethylene elastomers and avoiding additive-related issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polyisobutylene additive is incorporated into cling layer to improve tack, then cling properties are improved, but noise during unwinding increases and contamination of process equipment occurs
Solution Approach 1:
The patent removes the polyisobutylene additive from the cling layer formulation, replacing it with a blend of polyethylene elastomer and ULDPE/VLDPE. This extraction eliminates the source of noise and contamination problems while maintaining cling functionality through the elastomer component.
Solution Approach 2:
The patent substitutes expensive polyethylene elastomer (used at high levels) with a more cost-effective blend incorporating ULDPE/VLDPE. This replacement reduces material costs while achieving comparable cling performance through the synergistic blend formulation.
2Reliability
If polyethylene elastomer is used at high levels in cling layer to provide desirable cling properties, then cling performance is improved, but processing difficulty increases and cost increases
Solution Approach 1:
The patent modifies the compositional parameters of the cling layer by blending polyethylene elastomer with ULDPE/VLDPE in specific ratios. This parameter change reduces the elastomer content from potentially >90% to a more balanced formulation, improving processability while maintaining cling properties.
Solution Approach 2:
The patent creates a composite material system combining polyethylene elastomer with ULDPE/VLDPE. This composite approach leverages the advantages of both materials - the cling properties of elastomer and the processability/cost benefits of ULDPE/VLDPE - achieving a balanced formulation that resolves the contradiction.
3Reliability
If polyethylene elastomer is used at high levels in cling layer to provide desirable cling properties, then cling performance is improved, but material cost increases
Solution Approach 1:
The patent adjusts the compositional parameters by reducing polyethylene elastomer content and supplementing with ULDPE/VLDPE. This parameter optimization maintains adequate cling performance while reducing material cost through the use of more economical polymer components.
Solution Approach 2:
The patent substitutes expensive polyethylene elastomer with a more cost-effective ULDPE/VLDPE blend, reducing material costs while achieving comparable cling performance through the synergistic blend formulation.
Data Source
Figure 1
AI summary
Embodiments disclosed herein include multilayer films having at least an outer layer that includes 1) polyethylene elastomer and 2) ULDPE or VLDPE and that has a purge fraction greater than 20 percent as determined by Crystallization Elution Fractionation (CEF) test method. Embodiments disclosed herein also include related compositions to make such films and methods of making such films. The ULDPE or VLDPE can be made via Ziegler-Natta catalyst reaction techniques to provide the desired purge fraction.