Biodegradable Packaging Material with Dual-Layer Coating for Adhesion and Sealing
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Solution Overview
Problem
Biodegradable packaging materials using polylactide coatings face challenges with poor adhesion to fibre substrates and inadequate heat sealing abilities due to high melting points and fragility, leading to issues like tearing and pinholes during extrusion.
Innovation Solution
A biodegradable packaging material with a dual-layer coating system, where an inner layer contains a higher proportion of polylactide for improved adhesion and an outer layer with a blend of polylactide and biodegradable polyester for enhanced heat sealing, using polyesters like PBAT and PCL, and optionally incorporating acrylic copolymers for further improvement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polylactide is used as the coating polymer to achieve biodegradability, then biodegradability is improved, but adhesion to fibre substrate deteriorates and manufacturing precision worsens due to stiffness and fragility requiring high extrusion temperature
Solution Approach 1:
The patent changes the chemical composition parameters of the coating polymer by blending polylactide with specific biodegradable polyesters (polycaprolactone and polybutylene succinate adipate) in controlled ratios. This parameter change reduces the stiffness and fragility of pure polylactide, enabling successful extrusion at lower temperatures while maintaining biodegradability and improving adhesion to the fibre substrate.
Solution Approach 2:
The patent creates a composite coating material by combining polylactide with biodegradable polyesters (specifically polycaprolactone and polybutylene succinate adipate) in a blended ratio. This composite approach leverages the complementary properties of each component: polylactide provides biodegradability and barrier properties, while the added polyesters improve processability, reduce brittleness, and enhance adhesion to the fibre substrate during extrusion.
2Reliability
If polylactide is used as the outer coating layer to achieve biodegradability, then biodegradability is improved, but heat sealing ability deteriorates due to high melting point
Solution Approach 1:
The patent modifies the thermal properties of the outer coating layer by blending polylactide with biodegradable polyesters having lower melting points (polycaprolactone and polybutylene succinate adipate). This parameter change in the coating composition lowers the overall melting point of the outer layer, enabling effective heat sealing while preserving biodegradability.
Solution Approach 2:
The patent creates a composite outer coating layer by blending polylactide with biodegradable polyesters (polycaprolactone and polybutylene succinate adipate). This composite structure combines the high melting point and biodegradability of polylactide with the lower melting point and heat sealing capabilities of the added polyesters, achieving both biodegradability and improved heat sealing ability.
3Strength
If high extrusion temperature is used to process polylactide coating, then adhesion to fibre substrate is improved, but harmful factors increase due to breaking and tearing of the material
Solution Approach 1:
The patent changes the rheological parameters of the coating material by blending polylactide with biodegradable polyesters. This modification reduces the viscosity and improves the flow characteristics of the coating mixture, allowing it to be extruded at lower temperatures while still achieving adequate adhesion to the fibre substrate, thereby preventing breaking and tearing.
Solution Approach 2:
The patent creates a composite coating material with improved processability by blending polylactide with biodegradable polyesters. This composite formulation reduces the brittleness and improves the延展性 of the coating, enabling it to withstand the extrusion process at lower temperatures without breaking or tearing, while still achieving good adhesion to the fibre substrate.
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 solution achieves improved adhesion and heat sealing abilities without requiring multistage film lamination, while optimizing material costs by using less expensive polyesters only in the adhesion and heat sealing layers, and maintaining biodegradability.
Implementation Method 1
an inner coating layer against the fibre substrate, containing polylactide and a biodegradable polyester blended therewith to improve the adhesion between the layer and the fibre substrate
Implementation Method 2
its fairly high melting point, and the resulting poor heat sealing ability... considerably improved heat sealing ability
Implementation Method 3
polymeric coating layers extruded onto the same
Implementation Method 4
a high extrusion temperature... Because of the high temperature, polylactide runs the risk of breaking
Data Source
Figure 1~9
AI summary
The invention relates to a heat-sealable biodegradable packaging material, its manufacturing method and a product package formed thereof. The packaging material comprises a fibre substrate (1 ), an inner polymeric coating layer (2) against the same, which contains polylactide and a biodegradable polyester that is blended therewith to improve the adhesion between the layer and the fibre substrate, and an outer coating layer (3) that constitutes the outer surface of the material and contains polylactide and a biodegradable polyester that is blended therewith to improve the heat sealing ability of the layer, the portion of polylactide in the inner layer (2) being higher than that in the outer layer (3). The inner and/or outer coating layers (2, 3) can further have blended therewith a small amount of acrylic copolymer that improves the adhesion and/or heat sealing ability. The coating layers can be introduced onto the fibre substrate by extrusion or coextrusion.