Recyclable Release Liner Using Colloidal Silica Porous Network
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Solution Overview
Problem
Conventional solvent-based processes for producing release layers in adhesive tapes are undesirable due to handling requirements and environmental concerns, and existing release liners do not provide effective and recyclable solutions.
Innovation Solution
A release liner comprising a polymeric material with hydrogen atoms covalently bonded to oxygen, nitrogen, or sulfur atoms, combined with a silicone polyether containing polyoxoethylene or polyoxopropylene units, which forms a non-covalently bonded composition that acts as a self-supporting release layer, minimizing silicone transfer and enabling recyclability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If solvent-based processes are used to form release coatings, then the release coating can be applied to the backing layer, but special handling requirements and environmental concerns arise
Solution Approach 1:
The patent changes the chemical composition parameters of the release coating by using a water-based slurry instead of solvent-based solutions. The slurry comprises colloidal silica particles suspended in water with specific surface area ranges (150-400 m²/g) and controlled water content (30-70 wt%), eliminating the need for organic solvents while maintaining effective release properties.
Solution Approach 2:
The patent converts the typically problematic silica gel formation into a beneficial release mechanism. By controlling the slurry composition and drying process, silica gel forms a porous network structure that provides excellent release properties without requiring harmful solvents, turning a potential defect into a functional advantage.
2Productivity
If conventional release layers are used, then adhesive tape can be manufactured, but recyclability is limited due to covalent crosslinks between components
Solution Approach 1:
The patent employs a disposable-like approach where the release coating is designed to be easily removed and the backing layer to be recyclable. The colloidal silica-based coating can be stripped off during recycling processes, allowing the backing layer (especially paper-based substrates) to be reused without contamination from permanently bonded release agents.
Solution Approach 2:
The patent uses a composite material system combining colloidal silica particles with specific surface area characteristics and water-based binders. This composite structure provides the necessary release properties while maintaining compatibility with recyclable backing layers, as the inorganic silica particles do not form permanent covalent bonds with organic substrates.
3Reliability
If silicone-based release coatings are used, then release performance is improved, but silicone transfer to adjacent adhesives occurs
Solution Approach 1:
The patent utilizes the porous structure formed by colloidal silica particles after drying. The high surface area (150-400 m²/g) creates a three-dimensional network with numerous pores that physically trap the release coating material, preventing it from transferring to adjacent adhesive layers while still providing effective release functionality through the porous structure.
Solution Approach 2:
The colloidal silica particles act as an intermediary between the backing layer and the adhesive. The silica gel network provides a physical barrier that mediates the interaction between the substrate and adhesive, enabling release without direct contact and thus preventing silicone transfer contamination.
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 provides excellent release performance with low release force and high re-adhesion, suitable for paper-based products, while being recyclable and environmentally friendly, reducing the need for solvent-based processes.
Implementation Method 1
a release liner comprising a porous gel formed from colloidal silica particles having a surface area of from 150 to 400 meters squared per gram
Implementation Method 2
drying to evaporate the solvent
Data Source
AI summary
Release liners that can be included in various adhesive products are provided. A first release liner is a layer of a composition including a) a polymeric material having at least one hydrogen atom covalently bonded to an oxygen atom, a nitrogen atom, or a sulfur atom; and b) a silicone polyether comprising at least one of polyoxoethylene units or polyoxopropylene units. A second release liner includes a substrate and a coating of the above composition disposed on a major surface of the substrate. The present disclosure also provides an article including one of the above release liners and an adhesive layer disposed on a major surface of the release liner. The composition of the release liner can advantageously be dissolved and optionally recycled.