Aqueous Polymer Emulsion for Vacuum Impregnation Sealing
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Solution Overview
Problem
Existing vacuum impregnation compositions face challenges with electrochemical deposition on casting metals or parts co-molded by two different metal materials, leading to emulsion breaking and increased solvent requirements for cleaning, which hampers the effectiveness of the vacuum impregnation process in the electronics industry.
Innovation Solution
An aqueous polymer emulsion comprising at least one (meth)acrylic polymer prepared from alkyl (meth)acrylate and unsaturated carboxylic acid monomers, along with a corrosion inhibitor and a chelating agent, is used. The unsaturated carboxylic acid is present in an amount less than 3.5% by weight, which helps in preventing electrochemical deposition while maintaining good porosity sealing performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional impregnating composition is used for vacuum impregnation, then porosity sealing performance is achieved, but electrochemical deposition occurs on metal substrate causing emulsion breaking and polymer deposition
Solution Approach 1:
The patent introduces a specific polymer composition as an intermediary substance that prevents direct harmful interaction between the impregnating composition and metal substrate. The polymer is formulated to resist electrochemical deposition while maintaining sealing effectiveness, acting as a mediator that achieves porosity filling without causing emulsion breaking or polymer deposition on the metal surface.
Solution Approach 2:
The patent modifies the chemical composition parameters of the impregnating material by specifying exact ranges for unsaturated carboxylic acid content (0.1-3.5 wt%), hydroxyl group content (0.1-5.0 wt%), and carboxyl group content (0.1-5.0 wt%). These parameter changes optimize the polymer's resistance to electrochemical deposition while maintaining its sealing performance, resolving the contradiction between effectiveness and harmful side effects.
2Quantity of substance
If electrochemical deposition occurs on metal substrate, then metal ions release and deposit on surface, but this causes emulsion breaking and requires large amount of solvent for washing
Solution Approach 1:
The patent applies preliminary anti-action by formulating the impregnating composition with specific polymer characteristics (controlled unsaturated carboxylic acid content and functional group ratios) that preemptively prevent electrochemical deposition before it can occur. This prevents metal ion release and subsequent emulsion breaking, thereby avoiding the need for large amounts of solvent for cleaning and reducing both substance loss and processing steps.
3Reliability
If fixed-point dispersing method is used to seal pores, then sealants are applied on pore surface, but this changes part dimension, affects appearance, and sealant is easy to fail under impact
Solution Approach 1:
The patent replaces the mechanical dispersing method (fixed-point dispersing machine) with a chemical solution approach. Instead of mechanically forcing sealants into pores which distorts dimensions and affects appearance, the patent uses a chemically formulated polymer composition that naturally penetrates and seals pores through vacuum impregnation, maintaining part geometry and appearance while achieving reliable sealing that resists impact failure.
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 aqueous polymer emulsion effectively resists electrochemical deposition and ensures excellent porosity sealing on casting metals or parts co-molded by two different metal materials, thereby enhancing the efficiency and commercial viability of the vacuum impregnation process.
Implementation Method 1
By using a vacuum process, air is removed from the porosity of parts to be impregnated and replaced with the components in the emulsion
Implementation Method 2
In electrochemical deposition, metal ions release to the solution and deposit on the surface of the substrates
Implementation Method 3
The aqueous polymer emulsion comprises at least one chelating agent, wherein the at least one unsaturated carboxylic acid is present in an amount of less than 3.5% by weight
Data Source
AI summary
The present invention provides an aqueous polymer emulsion with satisfactory resistance to electrochemical deposition property and good porosity sealing performance on casting metals or parts co-molded by two different metal materials. The aqueous polymer emulsion comprises at least one (meth)acrylic polymer prepared by at least two monomers comprising at least one alkyl (meth)acrylate and at least one unsaturated carboxylic acid, at least one corrosion inhibitor, and at least one chelating agent, wherein the at least one unsaturated carboxylic acid is present in an amount of less than 3.5% by weight, based on the total weight of the monomers.