Solvent-Free Perfluoropolyether Adhesive for Void-Free Coatings
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Solution Overview
Problem
Current silicone adhesives, despite their excellent heat resistance and chemical resistance, often form voids on the coating film surface due to the evaporation of organic solvents during the curing process, which impairs the flatness and integrity of the film.
Innovation Solution
A curable perfluoropolyether adhesive composition comprising a linear perfluoropolyether compound, a fluorine-containing organohydrogenpolysiloxane, and a hydrosilylation-reaction catalyst, without any organic solvent, which also includes an organic solvent-free addition reaction regulator and hydrophobic silica powder to enhance scratch resistance and workability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If an organic solvent is added to the perfluoropolyether adhesive composition to improve workability and coating uniformity, then the ease of operation is improved, but voids are generated on the coating film surface during heating and curing due to solvent evaporation
Solution Approach 1:
The invention extracts and removes the organic solvent component from the adhesive composition entirely. By formulating a solvent-free perfluoropolyether adhesive composition, the source of void formation (evaporating solvent) is eliminated, while the composition maintains adequate workability through proper formulation of the polymer and crosslinking components.
Solution Approach 2:
The invention changes the physical and chemical parameters of the adhesive system by transitioning from a solvent-based formulation to a solvent-free formulation. This parameter change (removing the solvent phase) fundamentally alters the curing mechanism and eliminates the harmful effect of solvent evaporation, while maintaining the desired rheological properties through adjustment of polymer molecular weight and crosslinking density.
2Reliability
If the perfluoropolyether adhesive composition is heated for curing, then the chemical resistance and heat resistance are improved, but the organic solvent evaporates and creates voids on the film surface
Solution Approach 1:
The invention converts the potential harm of heating (which would evaporate solvent and create voids) into a benefit by using a solvent-free formulation. The heating process is retained for curing and achieving crosslinking, but without the harmful side effect of solvent evaporation. The low gas permeability of fluorine materials is thus not problematic since there is no gas (solvent vapor) to trap.
Solution Approach 2:
The harmful organic solvent component is extracted and removed from the composition. This eliminates the source of the harmful effect (solvent vapor generation during heating) while preserving the beneficial heating effect (curing and crosslinking that provides chemical and heat resistance).
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 composition produces a cured product with excellent heat resistance, chemical resistance, and solvent resistance, along with a smooth coating film free from voids, offering improved adhesion and scratch resistance.
Implementation Method 1
a fluorine-containing organohydrogenpolysiloxane having two or more H—SiOSiO structures per molecule; and a hydrosilylation-reaction catalyst
Data Source
AI summary
A curable perfluoropolyether adhesive composition including: (A) a linear perfluoropolyether compound having at least two alkenyl groups per molecule and having a perfluoropolyether structure containing a repeating unit represented by —CaF2aO— in a main chain, wherein “a” represents an integer of 1 to 6: 100 parts by mass; (B) a fluorine-containing organohydrogenpolysiloxane having at least two silicon atom-bonded hydrogen atoms per molecule: an effective curing amount; and (C) a hydrosilylation-reaction catalyst: a catalytic amount. The curable perfluoropolyether adhesive composition does not contain any organic solvent in the composition. This provides a curable perfluoropolyether adhesive composition that produces a cured product with excellent heat resistance, weather resistance, water repellency, oil repellency, chemical resistance, solvent resistance, etc., and particularly free of voids that may otherwise occur on the coating film surface during heating processes, as well as an adhesive and an adhesive tape including the cured product.