Multilayer cling film with LDPE release layer

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Solution Overview

Problem

Multilayer films used in packaging face issues such as excessive noise when unwound, the need for aging to achieve desired cling properties, contamination of process equipment, and difficulties in processing due to high levels of ethylene/alpha-olefin elastomers, which can result in unintended cling properties and increased costs.

Innovation Solution

The development of multilayer films comprising a cling layer with ethylene/alpha-olefin elastomers and ultra-low or very low density polyethylene, combined with a release layer of low density polyethylene, which are coextruded to form a tube and cooled to create a film with improved cling and reduced noise, eliminating the need for polyisobutylene additives and reducing processing challenges.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If polyisobutylene (PIB) additives are incorporated into the cling layer to improve tack, then cling force is improved, but the film becomes excessively noisy when unwound from film-roll

Engineering Contradiction:

Improvecling forceVSAvoidnoise

Core Design Contradiction:

ForceVSObject-affected harmful factors

Solution Approach 1:

The patent removes polyisobutylene (PIB) additives from the cling layer formulation, extracting the harmful element that causes excessive noise during unwinding while maintaining cling force through alternative polymer compositions including ethylene/alpha-olefin copolymers and ultra-low density polyethylene

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the compositional parameters of the cling layer by specifying precise density ranges (0.855-0.890 g/cm³) and molecular weight distributions of the polymer components, achieving both adequate cling force and reduced noise without requiring PIB additives

Inventive Principle:

Principle #35Parameter changes

2Force

If polyisobutylene (PIB) additives are used to achieve desired cling, then tack is improved, but the film must be aged for a period of time for the additive to migrate to the surface

Engineering Contradiction:

ImprovetackVSAvoidaging period

Core Design Contradiction:

ForceVSLoss of time

Solution Approach 1:

The patent eliminates polyisobutylene (PIB) additives from the formulation, removing the requirement for aging time that would be needed for additive migration to the surface, while achieving immediate tack through the inherent properties of the polymer blend

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The polymer blend components (ethylene/alpha-olefin copolymers and ultra-low density polyethylene) provide self-adhesive properties through their molecular structure and composition, eliminating the need for external additives and the aging process required for additive migration

Inventive Principle:

Principle #25Self-service

3Force

If polyisobutylene (PIB) additives are incorporated into the cling layer, then cling force is improved, but process equipment becomes contaminated

Engineering Contradiction:

Improvecling forceVSAvoidcontamination

Core Design Contradiction:

ForceVSObject-generated harmful factors

Solution Approach 1:

The patent removes polyisobutylene (PIB) additives from the cling layer, eliminating the source of contamination to process equipment while maintaining cling force through alternative polymer compositions that do not exhibit the same contaminating behavior

Inventive Principle:

Principle #2Taking out (Extraction)

4Force

If high levels of ethylene/alpha-olefin elastomers are used to achieve higher tack, then cling force is improved, but the films become very expensive and difficult to process using blown film techniques

Engineering Contradiction:

Improvecling forceVSAvoidprocessing difficulty

Core Design Contradiction:

ForceVSEase of manufacture

Solution Approach 1:

The patent optimizes the compositional parameters by blending ethylene/alpha-olefin copolymers with ultra-low density polyethylene in specific ratios, adjusting density (0.855-0.890 g/cm³) and molecular weight characteristics to achieve processability in blown film techniques while maintaining adequate cling force

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite material system combining ethylene/alpha-olefin copolymers with ultra-low density polyethylene, where the components work synergistically to provide both the required cling properties and processability, avoiding the difficulties associated with using high levels of单一 elastomers

Inventive Principle:

Principle #40Composite materials

Data Source

PatentEP3344454B1Multilayer films and methods thereof

Publication Date: 2023.06.21 DOW GLOBAL TECHNOLOGIES LLC

AI summary

Embodiments disclosed herein include multilayer films having a cling layer and a release layer, wherein the cling layer comprises (i) an ethylene/alpha-olefin elastomer, and (ii) a polyethylene polymer selected from ultra-low density polyethylene, a very low density polyethylene, or combinations thereof, and the release layer comprises a low density polyethylene (LDPE) having a density of from 0.915 to 0.930 g/cc, a melt index, I2, of from 1.0 to 30.0 g/10 min, and a molecular weight distribution, (Mw/Mn), as measured by the conventional calibration of triple detector gel permeation chromatography, of from 3.0 to less than 7.0.