Tie Layer Resin Adhesion to PET Films
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Solution Overview
Problem
Achieving good adhesion between polyethylene terephthalate (PET) and other polymer films, such as polyethylene (PE), is challenging due to PET's poor adhesion properties and high melting temperature, which complicates coextrusion and extrusion lamination processes, and existing tie-layer resins do not provide sufficient bonding.
Innovation Solution
A resin formulation comprising a polyolefin grafted with ethylenically unsaturated carboxylic acid or its derivative, combined with a Lewis acid catalyst, which does not include alkyl acrylate copolymers, offering improved thermal stability and adhesion to PET without the need for additional primers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a primer is used to improve adhesion between PET and PE films, then adhesion is improved, but manufacturing complexity and cost increase due to additional drying steps
Solution Approach 1:
The invention extracts and eliminates the primer component from the multilayer structure, replacing it with a tie-layer resin that provides adhesion functionality directly within the extrusion process, thereby removing the need for separate primer application and drying steps
Solution Approach 2:
The invention merges the adhesion-promoting function previously provided by primers into the tie-layer resin composition itself, combining multiple functions (adhesion, bonding, and processability) into a single integrated material layer
2Strength
If conventional tie-layer resins are used to improve adhesion between PET and PE, then some bonding is achieved, but adhesion is insufficient compared to EVOH or polyamide/PE structures
Solution Approach 1:
The invention changes the chemical and physical parameters of the tie-layer resin by incorporating specific functional groups (carboxylic acid, hydroxyl, amine) and controlling molecular weight, polydispersity, and composition ratios to optimize adhesion performance and bonding consistency
Solution Approach 2:
The invention uses composite resin formulations combining polyethylene with functional additives and modifiers to create a multicomponent tie-layer material that achieves superior adhesion to PET comparable to EVOH or polyamide systems
3Strength
If ethylene acrylate copolymers are used as tie-layers, then adhesion is improved, but thermal stability decreases for high-temperature extrusion processes
Solution Approach 1:
The invention changes the chemical composition parameters by replacing acrylate groups with thermally stable functional groups (carboxylic acid, hydroxyl, amine) while maintaining adhesion-promoting capabilities, enabling the resin to withstand high-temperature extrusion processes
Solution Approach 2:
The invention replaces thermally unstable but effective adhesion promoters (ethylene acrylate copolymers) with thermally stable alternatives that may require different formulation approaches, sacrificing some simplicity for thermal durability in high-temperature processing
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 resin demonstrates enhanced adhesion and thermal stability, enabling effective bonding in high-temperature extrusion processes and improving the sealing properties of PET films without the environmental drawbacks of traditional primers.
Implementation Method 1
0.001 to 0.20 weight percent (wt. %) of a catalyst comprising at least one Lewis acid
Implementation Method 2
a first polyolefin grafted with an ethylenically unsaturated carboxylic acid, an ethylenically unsaturated acid derivative or a combination thereof
Implementation Method 3
achieve the same level of adhesion that is seen in multilayer structures using EVOH or polyamide and PE films
Implementation Method 4
One theory behind this lack of improvement in bonding to PET films is the difficulties associated with the lack of functional groups and polarity
Implementation Method 5
The resin of the present invention shows higher thermal stability than the ethylene acrylate copolymer-based counterparts. Thermal stability of the resin is necessary for high temperature extrusion processes
Data Source
AI summary
The disclosure relates to a tie resin formulation for use as a tie layer in a multilayer structure. The resin includes a first polyolefin grafted with an ethylenically unsaturated carboxylic acid, an ethylenically unsaturated acid derivative or a combination thereof, and having a density of 0.857 to 0.885 g/cm3, and 0.001 to 0.20 weight percent (wt. %) of a catalyst comprising at least one Lewis acid, where the resin includes the catalyst and up to 99.999 wt. % of the first polyolefin, where the wt. % is based on a total weight of the resin.