Multilayer Binder Composition for Metal Adhesion and Extrusion
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Solution Overview
Problem
Current binders for multilayer structures with metallic layers face challenges in processability during extrusion coating/lamination, leading to 'neck-in' issues and inadequate stretchability, while also failing to provide excellent mechanical characteristics and adhesion to metal surfaces.
Innovation Solution
A binder composition comprising 60% to 95% low-density radical polyethylene as a matrix, combined with 5% to 40% of a mixture of metallocene polyethylene and radical low-density polyethylene co-grafted with an unsaturated carboxylic acid, specifically maleic anhydride, which enhances both processability and adhesion to metal surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a binder comprising metallocene polyethylene co-grafted with unsaturated carboxylic acid is used to improve adhesion to metal, then adhesion properties are improved, but processability during extrusion coating/lamination deteriorates leading to neck-in problems
Solution Approach 1:
The patent changes the chemical composition parameters of the binder by incorporating radical low-density polyethylene (LDPE) alongside metallocene polyethylene co-grafted with unsaturated carboxylic acid. This parameter modification adjusts the balance between adhesion properties (provided by the co-grafted polyethylene) and processability (improved by the radical LDPE component), thereby resolving the contradiction between strong metal adhesion and acceptable extrusion processability without severe neck-in problems
Solution Approach 2:
The invention creates a composite binder system combining two distinct polyethylene types: metallocene polyethylene co-grafted with unsaturated carboxylic acid (for adhesion) and radical low-density polyethylene (for processability). This composite approach allows the binder to simultaneously achieve good adhesion to metal surfaces and acceptable processability during extrusion coating/lamination, avoiding the extreme neck-in problems associated with pure co-grafted polyethylene systems
2Ease of manufacture
If conventional low-density radical polyethylene is used as binder matrix to ensure processability, then processability is improved, but adhesion to metal surface deteriorates
Solution Approach 1:
The patent merges two previously separate functional components into a single binder system: conventional radical low-density polyethylene (提供 processability) and metallocene polyethylene co-grafted with unsaturated carboxylic acid (提供 adhesion to metal). By combining these components in specific proportions, the binder achieves both adequate processability during extrusion and satisfactory adhesion to metal surfaces, resolving the contradiction between these two opposing requirements
3Strength
If terpolymers are used as adhesion agent to achieve excellent adhesion properties, then adhesion to metal is improved, but production cost increases due to high pressure reactor requirements
Solution Approach 1:
The patent replaces expensive terpolymer adhesion agents (requiring high pressure reactor production) with a more economical alternative: metallocene polyethylene co-grafted with unsaturated carboxylic acid combined with radical low-density polyethylene. This substitution maintains adequate adhesion to metal surfaces while significantly reducing production costs by avoiding the need for expensive high pressure reactor facilities and complex terpolymer synthesis processes
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 proposed binder composition significantly improves processability and adhesion to metal surfaces, reducing 'neck-in' issues and achieving superior mechanical properties, making it industrially viable for applications like packaging films.
Implementation Method 1
this binder is more specifically an extrusion binder based on co-grafted polyethylenes... one metallocene and the other low-density radical, said mixture being co-grafted with an unsaturated carboxylic acid... adhesion also capable of improving the mechanical properties of the assembly called binder
Data Source
AI summary
The present invention relates to a binder for multilayer structures, which includes: 60 % to 95 %, by weight of the composition, of a matrix made of a polyethylene selected from among the low-density radical polyethylenes (LDPE); 5 % to 40 %, by weight of the composition, of a mixture of two polyethylenes, the first polyethylene consisting of a metallocene polyethylene, co-grafted by an unsaturated carboxylic acid, grafting monomer, the grafts of unsaturated carboxylic acid being more than 0.5 %, by weight of the mixture, characterised in that the second polyethylene consists of a low-density radical polyethylene (LDPE) and in that the MFI or melt flow index (standard ASTM D1238, at 190 °C, under 2.16 kg) is 4 to 15 g/10 min. The invention also relates to a multilayer structure that includes the binder and to a method for manufacturing said multilayer structure.