Polymeric Composite Microspheres for Low Friction Coatings
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Solution Overview
Problem
Current aqueous dispersions of silicone-composite microspheres are not compatible with coating compositions, leading to film defects and high costs, limiting their use in coatings due to low solids content and high cycle times.
Innovation Solution
A process involving the polymerization of polysiloxane and monoethylenically unsaturated nonionic monomers with specific polyalkylene oxide or anionic polyalkylene oxide salts to create composite microspheres with a wide particle size range, allowing for higher solids content and defect-free coatings with low friction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional silicone dispersions are used in aqueous coating compositions, then the coefficient of friction is reduced and wear resistance is improved, but film defects occur and compatibility is poor
Solution Approach 1:
The patent uses a surfactant as an intermediary substance to mediate between the hydrophobic silicone particles and the aqueous coating composition. The surfactant adsorbs at the interface, providing steric stabilization and preventing film defects while maintaining the low friction properties of silicone
Solution Approach 2:
The invention creates a composite system where silicone particles are combined with polymer binders, matting agents, and surfactants in an aqueous dispersion. This composite approach allows the silicone to provide low friction while the other components ensure compatibility and defect-free film formation
2Manufacturing precision
If batch suspension polymerization is used to produce silicone-composite microspheres, then composite particles with designed shapes are achieved, but cycle times are long and solids content is limited
Solution Approach 1:
The patent prepares pre-formed silicone particles with controlled sizes and shapes before the polymerization step. This preliminary action allows the subsequent polymerization to proceed more efficiently, reducing overall cycle time while maintaining particle shape control
Solution Approach 2:
The invention optimizes polymerization parameters including temperature, initiator concentration, and monomer composition to accelerate the polymerization rate. These parameter changes reduce cycle time from conventional batch processes while maintaining solids content above 30%
3Productivity
If concentration of silicone additive is increased to reduce cycle times and increase solids content, then productivity is improved, but cost increases due to high silicone prices
Solution Approach 1:
The patent optimizes the silicone particle size distribution and concentration to achieve maximum solids content (above 30%) with minimum silicone usage. By controlling particle size and distribution, the formulation achieves high productivity without proportionally increasing expensive silicone content
Solution Approach 2:
The invention creates a cost-effective composite where inexpensive polymer binders and matting agents are combined with smaller amounts of expensive silicone. This composite approach achieves the desired performance and solids content while controlling material costs
4Ease of operation
If organic non-film-forming matting agents are used to provide ease of application and surface roughness, then ease of operation is improved, but coating compatibility and film integrity are compromised
Solution Approach 1:
The patent uses a surfactant as an intermediary that bridges the hydrophobic matting agents and the aqueous coating matrix. The surfactant ensures uniform dispersion and strong interfacial adhesion, allowing matting agents to provide surface roughness without compromising film integrity
Solution Approach 2:
The invention creates a composite system where film-forming polymers and non-film-forming matting agents work synergistically. The polymer matrix provides film integrity while the matting agents provide surface roughness, with surfactants ensuring compatible interaction between components
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 process results in defect-free coatings with reduced coefficients of friction and increased solids content, making them suitable for various applications without the need for expensive monomers, thus overcoming the limitations of existing technologies.
Implementation Method 1
functionalized with from 0.05 to 5 weight percent structural units of a nonionic polyalkylene oxide or anionic polyalkylene oxide salt of a distyryl or tristyryl phenol
Implementation Method 2
contacting, under polymerization conditions, an aqueous dispersion of first composite microspheres with first stage monomers to grow out the first composite microspheres
Data Source
AI summary
The present invention relates to a composition comprising an aqueous dispersion of polymeric composite microspheres comprising an aqueous dispersion of polymeric composite microspheres that comprise a polysiloxane and a polymer, as defined herein, and a suspension polymerization process for making the composition. The composition is useful for making defect free coatings with a relatively low coefficient of friction.