Laminate Printing Layer Separation to Prevent Re-Adhesion
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Solution Overview
Problem
Existing methods for detaching printing layers from plastic base materials in laminates during recycling face issues of deteriorating detachability and re-adhesion, leading to poor quality of recycled materials due to increased amounts of printing layers and stirring rates.
Innovation Solution
A method involving immersing a laminate in a detachment liquid containing water and a surfactant, with specific particle size and span value controls, to detach a printing layer with a median diameter of 1 μm or more, using a basic aqueous solution and incorporating dispersants to suppress re-adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the amount of laminate to be treated with alkali aqueous solution is increased to improve treatment efficiency, then productivity is improved, but detachability deteriorates
Solution Approach 1:
A surfactant is introduced as an intermediary substance between the alkali aqueous solution and the printing layer. The surfactant mediates the detachment process by reducing surface tension and improving wetting, allowing effective detachment even when large amounts of laminate are treated simultaneously, thus resolving the contradiction between productivity and detachability
Solution Approach 2:
The invention changes the chemical parameters of the detachment liquid by adding surfactants and controlling pH levels. This parameter modification enhances the detachment capability of the alkali aqueous solution, enabling it to effectively detach printing layers even under high-productivity conditions where large volumes of laminate are processed
2Productivity
If the amount of printing layer component in treatment liquid increases, then treatment efficiency is improved, but re-adhesion becomes more likely
Solution Approach 1:
The surfactant acts as a protective intermediary that keeps detached printing layer components dispersed in the treatment liquid. By reducing surface tension and preventing coalescence, the surfactant prevents re-adhesion even when printing layer components are present in large amounts, allowing high treatment efficiency without the harmful re-adhesion effect
Solution Approach 2:
The invention converts the potentially harmful presence of大量 printing layer components in the treatment liquid into a benefit. By using surfactants, the printing layer components that would normally cause re-adhesion are instead kept stably dispersed, and the high concentration of detached material indicates effective detachment, thus converting what was a harmful factor into a sign of successful treatment
3Reliability
If the stirring rate is increased to improve detachability, then detachability is improved, but printing layer becomes finely dispersed and more likely to re-adhere
Solution Approach 1:
The surfactant serves as a protective intermediary between the stirring action and the printing layer components. It allows vigorous stirring to achieve good detachability while simultaneously preventing the detached printing layer from re-adhering by maintaining stable dispersion through surface tension reduction and electrostatic repulsion
Solution Approach 2:
The invention changes the physical-chemical parameters of the treatment liquid by adding surfactants, which modify surface tension and colloidal stability. This parameter change allows the system to tolerate higher stirring rates that improve detachability without suffering from the harmful effect of printing layer re-adhesion, as the surfactant maintains dispersion stability
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 method effectively separates and recovers high-quality plastic base materials by controlling detachability and re-adhesion, enabling efficient recycling and production of high-quality molding materials.
Implementation Method 1
immersing a laminate including at least a plastic base material layer and a printing layer in a detachment liquid
Implementation Method 2
treating the laminate including a detachment layer containing a polyurethane resin having a predetermined acid value with an alkali aqueous solution
Data Source
AI summary
In the present disclosure, a method for separating and recovering a laminate is provided, the method including a step of immersing a laminate including at least a plastic base material layer and a printing layer in a detachment liquid to detach the printing layer so that a volume-based median diameter (D50) of a printing layer component detached from the plastic base material layer becomes 1 μm or more and recovering a plastic base material, in which a content rate of the printing layer is 0.01 mass % or more of a total mass of the detachment liquid.