Acrylate-Impregnated Insulating Laminates for Mica Bonding
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Solution Overview
Problem
The production of aramid/mica insulating sheets faces challenges due to the poor mechanical strength of mica, which leads to detachment issues and difficulties in laminating and impregnating with resins.
Innovation Solution
A multilayer laminate configuration is introduced, comprising nonwoven backing sheets with crystalline silicate mineral powder, an inner layer of heat-resistant floc and binder or polymeric film, and a coating of acrylate resin. This configuration enhances surface cohesion and compactness by deeply penetrating the resin into the sheets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mica is introduced into aramid paper structure to improve resistance to partial discharge, then electrical insulation properties are improved, but mechanical strength decreases and surface cohesion becomes poor
Solution Approach 1:
An adhesive resin layer comprising acryloyl-based compounds is introduced as an intermediary between mica particles and aramid fibers. This adhesive resin penetrates into the aramid paper structure and bonds mica particles to aramid fibers, improving surface cohesion and mechanical strength while maintaining the electrical insulation properties and resistance to partial discharge provided by mica.
2Strength
If adhesive resin layer is applied to already-formed aramid/mica paper to improve bonding, then surface bonding between aramid fibers and mica is increased, but penetration depth is limited and compactness is only partially increased
Solution Approach 1:
The adhesive resin is applied to the aramid/mica paper before final consolidation and curing processes. This preliminary application allows the resin to penetrate deeply into the paper structure while the materials are still in a more receptive state, ensuring thorough impregnation and strong bonding throughout the bulk material rather than just on the surface.
Solution Approach 2:
The viscosity and application parameters of the adhesive resin are optimized to enable deep penetration into the aramid paper structure. The resin composition is designed to flow effectively through the paper matrix during application, then cure to form strong bonds, achieving both deep penetration and high surface bonding.
3Stability of the object's composition
If aramid nanofibers are used instead of microfibers to increase surface area of interaction, then compactness is promoted, but process complexity and cost increase
Solution Approach 1:
Instead of using complex and expensive aramid nanofiber production processes, the invention employs conventional aramid microfibers combined with an adhesive resin system. This approach achieves the desired compactness and bonding by using readily available materials and simpler, more cost-effective manufacturing processes that are already established in the industry.
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 proposed solution effectively stabilizes mica particles on aramid fibers, preventing detachment and improving the compactness and processability of aramid/mica insulating sheets, while maintaining excellent electrical properties.
Implementation Method 1
a process in which a nonwoven backing sheet comprising 15 to 80 percent by weight of a crystalline silicate mineral powder, in particular mica, is impregnated with a coating layer of a resin based on acrylate derivatives which penetrates deep into the sheet itself
Implementation Method 2
the coating layer compacting and permanently fixing the mica powder
Data Source
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AI summary
The present invention relates to a multilayer laminate comprising at least three layers, wherein the two outer layers are each nonwoven backing sheet (7) containing a crystalline silicate mineral powder impregnated with a coating of an impregnating resin based on acrylate derivatives, which is suitable for increasing the compactness of the insulating sheet and for preventing the silicate mineral powder from detaching from the aramid fiber during use; the multilayer laminate having an inner layer being free of crystalline silicate mineral powder that comprises either i) heat resistant floc and binder, or ii) heat resistant polymeric film. The impregnating resin also comprises an organic solvent, which is capable of reducing the viscosity thereof and of promoting its deep penetration into the sheet. In addition, the impregnating resin comprises a UV polymerization photoinitiator which is suitable for curing the resin, only after said resin has been applied to the sheet and has penetrated deeply therein. The invention also describes the method for impregnating the insulating sheets.