PLA Core Film Adhesive Interdiffusion via Coextrusion
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Solution Overview
Problem
Current adhesive technologies face challenges in achieving optimal interdiffusion and compatibility between polylactic acid (PLA) core film layers and adhesive layers, leading to suboptimal performance in pressure-sensitive adhesive tapes and other applications.
Innovation Solution
A method involving melt extrusion of multiple layers, including a core film layer with at least 50% polylactic acid polymer, an adhesive layer miscible with the core layer, and an optional release layer, where the adhesive layer is coextruded or coated on the core layer, promoting interdiffusion regions and improved compatibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional adhesive technologies are used with PLA core film layers, then the adhesive layers can be applied to the core layer, but optimal interdiffusion and compatibility between the layers are not achieved
Solution Approach 1:
The patent modifies the chemical composition parameters of the adhesive layer by incorporating esters of C1-C10 dicarboxylic acids and specific vinyl polymers that are compatible with polylactic acid. This parameter change enables optimal interdiffusion and compatibility between the adhesive layer and PLA core film layer, resolving the contradiction between adhesion performance and interdiffusion quality.
Solution Approach 2:
The patent creates a composite adhesive layer system combining multiple polymer components (esters of dicarboxylic acids, vinyl polymers, and optional third polymers) that work synergistically with the PLA core film. This composite material approach achieves both strong adhesion performance and optimal interdiffusion compatibility that single-material adhesives cannot achieve.
2Reliability
If multiple layers are sequentially extruded or coextruded, then the interdiffusion between layers is enhanced, but the manufacturing process complexity increases
Solution Approach 1:
The patent combines multiple adhesive layer components (esters of dicarboxylic acids, vinyl polymers, and optional third polymers) into a single coextruded adhesive layer formulation. This merging approach achieves enhanced interdiffusion and layer compatibility while avoiding the complexity of multiple separate extrusion steps, as the components are combined in a single adhesive composition that is extruded in one operation.
3Reliability
If the adhesive layer comprises moieties miscible with the core film layer composition, then interdiffusion regions are present between layers, but the formulation complexity increases
Solution Approach 1:
The patent applies local quality by ensuring that specific portions of the adhesive layer formulation (the esters of C1-C10 dicarboxylic acids and vinyl polymers) have miscibility characteristics specifically matched to polylactic acid. This targeted local compatibility approach enables effective interdiffusion and interlayer bonding without requiring the entire formulation to be overly complex, as only specific components need to exhibit miscibility with PLA.
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
Enhances the interdiffusion between the core and adhesive layers, resulting in improved adhesion and release properties, such as reduced noise and increased film area production, while maintaining the biodegradability and renewable aspects of PLA-based materials.
Implementation Method 1
The adhesive layer comprises moieties that are miscible in the composition of the core film layer such that regions of interdiffusion are present between the core film layer and adhesive layer
Implementation Method 2
A method involving melt extrusion of multiple layers, including a core film layer with at least 50% polylactic acid polymer
Data Source
AI summary
A method of making an adhesive article is described comprising melt extruding a core film layer comprising a composition comprising at least 50% of a polylactic acid polymer. The method further comprises melt extruding an adhesive layer on a major surface of the core film layer such that regions of interdiffusion are present between the core film layer and adhesive layer. The adhesive layer may comprise C1-C10 (meth)acrylic acid or ester thereof, vinyl acetate, ethylene vinyl acetate, hydrolysed polyvinyl alcohol and combinations thereof. The adhesive layer may also be a pressure sensitive adhesive. The method further comprises melt extruding a release film layer on an opposing major surface of the core film layer. The layers are sequentially extruded or co-extruded and can be uniaxially or biaxially oriented. Articles comprising a core film layer comprising a composition comprising at least 50% of a polylactic acid polymer and an adhesive layer disposed on a major surface of the core layer are also described.