LDPE Acid Copolymer Blend Adhesion Aluminum Foil
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Low density polyethylene (LDPE) exhibits low adhesion to polar substrates such as aluminum foil and metalized films, leading to compromised barrier properties and potential food spoilage, especially at high extrusion coating line speeds.
Innovation Solution
A polymer blend comprising at least 90% by weight low density polyethylene (LDPE) and from 1% to 10% by weight acid copolymer, where the LDPE has a specific melt index and molecular weight distribution, and the acid copolymer is a reaction product of ethylene, monocarboxylic acid, and alkyl acrylate monomers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If LDPE is extruded and coated at high temperatures to enhance adhesion to polar substrates, then adhesion strength is improved, but oxidation occurs at the polymer surface which can compromise material integrity
Solution Approach 1:
The patent changes the chemical composition parameter of the polymer by incorporating acid copolymer (containing carboxylic acid groups) into the LDPE matrix. This compositional modification enables the material to achieve adequate adhesion at lower extrusion temperatures, thereby reducing oxidation while maintaining bonding strength to polar substrates like aluminum foil.
2Productivity
If extrusion coating line speed is increased to improve productivity, then output is improved, but oxidation time is reduced leading to decreased adhesion
Solution Approach 1:
The patent modifies the chemical composition of the polymer blend by adding acid copolymer components, which fundamentally changes the adhesion mechanism. This allows the process to run at high line speeds with sufficient oxidation time because the acid groups provide inherent adhesion capability that doesn't rely solely on oxidation-generated carbonyl groups, thus decoupling productivity from adhesion quality.
3Ease of manufacture
If LDPE is used for extrusion coating due to its processability, then ease of manufacture is improved, but adhesion to polar substrates deteriorates
Solution Approach 1:
The patent creates a composite polymer system by blending LDPE (which provides excellent processability) with acid copolymer (which provides adhesion through carboxylic acid groups). This composite approach allows the material to simultaneously inherit the processability benefits of LDPE and the adhesion benefits of the acid-containing copolymer, resolving the contradiction between ease of manufacture and adhesion performance.
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 polymer blend achieves improved adhesion to polar substrates, maintaining effective barrier properties even at medium to high extrusion coating line speeds, thereby preventing food spoilage.
Implementation Method 1
adhesion to polar substrates is driven by polar functional groups such as carbonyl groups
Implementation Method 2
High-temperature extrusion coating promotes oxidation at the polymer surface, which can generate carbonyl groups
Data Source
AI summary
The polymer blend includes at least 90% by weight low density polyethylene (LDPE) polymer and from 1% to 10% by weight acid copolymer based on the total weight of the polymer blend. In the polymer blend, the LDPE polymer has a melt index (I? 2 #191) from 2 g/10 min to 8 g/10 min as determined in accordance with ASTM D1238, and a molecular weight distribution from 5 to 10.5. In the polymer blend, the acid copolymer is a polymerized reaction product of: at least 60% by weight ethylene, based on the total weight of the monomers present in the ethylene acid copolymer; from 1% to 20% by weight monocarboxylic acid monomer, based on the total weight of the monomers present in the ethylene acid copolymer; and from 0 to 20% by weight alkyl acrylate monomer, based on the total weight of the monomers present in the ethylene acid copolymer.