Silica-Coated Silicone Elastomer Particles for Resin Stress Relaxation
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Solution Overview
Problem
Silicone elastomer particles tend to agglomerate, leading to poor dispersibility and reduced effectiveness in resin and cosmetic applications, making it challenging to achieve desired properties such as stress relaxation and soft touch feel.
Innovation Solution
A method involving the hydrolytic condensation of tetraalkoxysilane with spherical silicone elastomer particles, an alkaline substance, and cationic surfactants or polymeric compounds to coat the particles with silica, preventing agglomeration and enhancing dispersibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If spherical silicone elastomer particles are used as stress relaxing agents, then rubber-like elasticity and stress relaxation properties are achieved, but the particles have a strong tendency to agglomerate and poor dispersibility in resins and cosmetic materials
Solution Approach 1:
Silica particles are introduced as an intermediary substance that coats the surface of the silicone elastomer particles. This silica coating acts as a mediator that prevents direct contact and adhesion between elastomer particles, thereby reducing agglomeration tendency while maintaining the underlying rubber-like elasticity and stress relaxation properties of the core material.
Solution Approach 2:
The invention creates a composite particle structure consisting of a silicone elastomer core and a silica shell. This composite structure combines the beneficial properties of both materials: the elastomer provides stress relaxation and rubber-like elasticity, while the silica coating improves dispersibility and reduces agglomeration. The composite nature allows both functions to coexist without compromising either property.
2Ease of manufacture
If ball mill or hybridizer is used to dry mix and apply impact forces to break down agglomerated particles, then particle dispersion is attempted, but the elastomer core particles absorb the impact forces making it difficult to properly coat them
Solution Approach 1:
The invention replaces the mechanical impact-based coating approach (ball mill, hybridizer) with a chemical solution-based coating method. Instead of using mechanical force to break down and coat particles, the process uses hydrolytic condensation of tetraalkoxysilane in an aqueous medium to form a silica coating that deposits on the particle surfaces through chemical reactions, avoiding the need for high-impact mechanical processing.
Solution Approach 2:
The invention changes the fundamental parameter of the coating process from mechanical impact to chemical deposition. By controlling parameters such as pH (using alkaline substances), temperature, and the concentration of tetraalkoxysilane and cationic surfactants, the coating is formed through controlled chemical reactions rather than mechanical forces, making the process gentler on the elastomer cores while achieving effective coating.
3Productivity
If spray drying is used to remove water from aqueous dispersion to produce coated particles, then water removal is achieved, but non-coating metal oxide particles are sometimes produced resulting in poor production efficiency
Solution Approach 1:
The invention performs preliminary actions to ensure proper coating before the drying step. By pre-forming silica nuclei through hydrolytic condensation of tetraalkoxysilane in the aqueous dispersion and using cationic surfactants to promote uniform distribution and adhesion to particle surfaces, the coating is established before water removal. This preliminary coating formation prevents non-coating particles during subsequent spray drying, improving both production efficiency and coating uniformity.
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 method efficiently produces silica-coated silicone elastomer particles with improved dispersibility and stress relaxation properties, suitable for both resin and cosmetic applications, while maintaining a soft touch feel and allowing inclusion in aqueous materials without dispersants.
Implementation Method 1
adding (E) a tetraalkoxysilane to a liquid containing (A) spherical silicone elastomer particles, (B) an alkaline substance, (C) one or more ingredient selected from cationic surfactants and cationic water-soluble polymeric compounds and (D) water, and subjecting the tetraalkoxysilane to hydrolytic condensation
Data Source
AI summary
A method for producing silica-coated spherical silicone elastomer particles which includes a step in which a tetraalkoxysilane (E) is added to a liquid comprising spherical silicone elastomer particles (A), an alkaline substance (B), one or more ingredients (C) selected from among cationic surfactants and cationic water-soluble polymers, and water (D), and the tetraalkoxysilane is hydrolyzed and condensed to thereby coat the surfaces of the spherical silicone elastomer particles with silica.