PTFE Non-Stick Coating Abrasion Resistance
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Solution Overview
Problem
Multi-layer PTFE non-stick coatings suffer from poor abrasion resistance and non-stick properties after intensive abrasion due to the exposure of filler-containing middle layers, which have lower non-stick performance compared to the top layers, and the addition of fillers or film-forming aids can lead to crack formation and negative impacts on non-stick properties.
Innovation Solution
A non-stick coating with a top layer consisting of 98-100% PTFE and up to 2% pigments, free of melt-processable fluoropolymers, and an adhesion promoter layer with a dry film thickness of 5-25 μm, where the top layer is produced using high molecular weight PTFE obtained by emulsion polymerization and modified with perfluoropropyl vinyl ether, and applied with a crack-free dry film thickness of up to 45 μm through a specific application method.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a multi-layer PTFE non-stick coating with filler-containing middle layers is used, then abrasion resistance is improved, but non-stick properties deteriorate after intensive abrasion due to exposure of filler-containing middle layers
Solution Approach 1:
The coating is divided into multiple layers with distinct functions: a bottom layer containing fillers for abrasion resistance, an intermediate layer as a transition zone, and a top layer of pure PTFE for non-stick properties. This segmentation allows each layer to optimize its specific function without compromising the others.
Solution Approach 2:
The coating system uses composite material structure where the bottom layer combines PTFE with inorganic fillers (aluminum oxide, silicon carbide) to achieve high abrasion resistance, while the top layer uses pure PTFE to maintain excellent non-stick properties. The composite structure ensures that fillers remain confined to the bottom layer.
2Reliability
If the top layer dry film thickness is increased to improve non-stick properties, then non-stick performance is improved, but crack formation occurs due to low top layer dry film thickness
Solution Approach 1:
The patent optimizes the thickness parameters of each layer: the bottom layer is set at 5-25 μm and the top layer at 20-45 μm. These specific thickness ranges ensure that the top layer is thick enough to provide excellent non-stick properties while remaining thin enough to avoid crack formation during drying and curing.
Solution Approach 2:
The coating process includes a preliminary drying step at 60-110°C for 5-15 minutes before final sintering at 410-430°C. This preliminary action removes excess moisture and prepares the coating for uniform sintering, preventing crack formation during the curing process.
3Strength
If inorganic fillers are added to improve abrasion resistance, then abrasion resistance is improved, but non-stick properties deteriorate due to filler exposure after abrasion
Solution Approach 1:
Inorganic fillers are localized exclusively to the bottom layer of the coating, where they provide abrasion resistance. The top layer is composed of pure PTFE without any fillers, ensuring that only non-stick material is exposed on the surface. This local quality distribution allows each layer to perform its specific function optimally.
4Force
If adhesion promoter layer thickness is increased to improve adhesion, then adhesion is improved, but overall coating thickness increases leading to longer drying and curing times
Solution Approach 1:
The adhesion promoter layer thickness is optimized to 5-25 μm, which provides sufficient adhesion strength while minimizing the overall coating thickness. This parameter optimization ensures strong bonding to the substrate without excessively increasing the time required for drying and curing processes.
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 significantly improved abrasion resistance and durable non-stick properties by maintaining the top layer's integrity without filler exposure, ensuring high non-stick performance even after abrasion and preventing crack formation at high layer thicknesses.
Implementation Method 1
it contains 1 to 9 wt.% of high molecular weight modified PTFE, which contains CF2CF2CF2CF(CF3)OCH3 side chains and is obtained by emulsion polymerization of TFE
Implementation Method 2
The layers are subsequently bonded to one another and to the surface of the object by drying and sintering or melting at 410 to 430 °C
Implementation Method 3
Hard inorganic fillers are usually used to improve the abrasion resistance of multi-layered PTFE non-stick coatings
Data Source
Figure 1~4
Figure 5~8
AI summary
An anti-stick coating for an article comprises at least one adhesion promoter layer (V) applied to a surface of the article and a topcoat layer (D) arranged over the adhesion promoter layer, wherein the adhesion promoter layer has a dry film thickness of 5 to 25 µm and the topcoat layer has a dry film thickness of 20 to 45 µm. To achieve an improved combination of anti-stick effect and abrasion resistance, it is proposed that the topcoat contain 98 to 100 wt.% PTFE and optionally up to 2 wt.% pigments based on the total solids content of the topcoat and be free of melt-processable fluoropolymers, and that, in addition to high molecular weight PTFE obtained by emulsion polymerization of TFE, it contains 1 to 9 wt.% of a high molecular weight modified PTFE containing < 1 wt.% perfluoropropyl vinyl ether (PPVE) as a modifying co-monomer and obtained by suspension polymerization.