PVOH Laminate Structure for Fast Water-Triggered Delamination
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Solution Overview
Problem
Existing laminates with multiple resin layers are difficult to sort and recycle due to insufficient delamination speed and bonding strength, particularly in high-temperature conditions, leading to instability and poor recyclability.
Innovation Solution
A laminate structure with a polyvinyl alcohol resin intermediate layer and outer layers having a significant difference in water vapor transmission rate (WVTR), causing rapid delamination when immersed in water, thereby enhancing recyclability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If an intermediate layer of water-soluble resin is used to enable delamination, then recyclability is improved, but delamination speed is insufficient
Solution Approach 1:
The patent changes the chemical composition parameter of the intermediate layer from conventional water-soluble resins (polyvinyl alcohol, ethylene-modified polyvinyl alcohol) to isocyanate-modified polyvinyl alcohol resin. This parameter change fundamentally alters the delamination mechanism and speed while maintaining recyclability through water immersion.
Solution Approach 2:
The patent utilizes the phase transition property of isocyanate-modified polyvinyl alcohol resin when exposed to water. The resin undergoes rapid dissolution and decomposition, causing immediate delamination of the laminate layers. This phase transition occurs much faster than conventional water-soluble resins, solving the delamination speed problem.
2Ease of operation
If wax is used as bonding agent between layers, then delamination is improved, but bonding strength becomes insufficient at high temperatures
Solution Approach 1:
The patent replaces wax with isocyanate-modified polyvinyl alcohol resin as the intermediate layer material. This parameter change provides both strong bonding strength at high temperatures and rapid water-triggered delamination, simultaneously resolving both requirements.
Solution Approach 2:
The isocyanate-modified polyvinyl alcohol resin acts as an intermediary layer that provides dual functionality: strong adhesion to both outer layers under normal and high-temperature conditions, and rapid decomposition upon water contact to enable delamination. This intermediary resolves the contradiction between bonding strength and delamination ease.
3Ease of operation
If polyolefin layer is bonded via wax to polyvinyl alcohol resin film, then delamination is easy, but separation occurs during distribution due to insufficient bonding strength
Solution Approach 1:
The patent changes the intermediate layer material parameters to isocyanate-modified polyvinyl alcohol resin, which provides superior bonding strength compared to wax. This ensures reliable adhesion during distribution and handling while maintaining the ability to delaminate rapidly when exposed to water for recycling.
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 laminate achieves faster delamination and improved recyclability by exploiting the differential water vapor transmission rates of its outer layers, ensuring efficient separation and recovery of components.
Implementation Method 1
the intermediate layer contains a polyvinyl alcohol resin... when the laminate is immersed in water, the first outer layer and the second outer layer are delaminated in a shorter period of time, whereby the intermediate layer of the polyvinyl alcohol resin is exposed to water and speedily dissolved in water
Implementation Method 2
A difference in water vapor transmission rate between the first outer layer and the second outer layer is not less than 100 cc·30 μm/m2·day... the first outer layer and the second outer layer have different properties and exhibit different behaviors with respect to water
Data Source
AI summary
A laminate is provided, which requires a shorter period of time for delamination thereof and hence is excellent in recoverability. The laminate includes a first outer layer, an intermediate layer, and a second outer layer which are disposed in this order. The intermediate layer contains a polyvinyl alcohol resin. A difference in water vapor transmission rate between the first outer layer and the second outer layer is not less than 100 cc·30 μm/m2·day, and the water vapor transmission rate of the first outer layer and the water vapor transmission rate of the second outer layer satisfy the following expression (1):WVTR1<WVTR2 (1)wherein WVTR1 is the water vapor transmission rate of the first outer layer and WVTR2 is the water vapor transmission rate of the second outer layer.