Composite particle dispersions
First Claim
1. A process for preparing a dispersion of composite particles, which process comprises mixing first particles with a liquid dispersion of polymer particles, the polymer particles being ionically and/or sterically colloidally stable against particle-particle flocculation and agglomeration, wherein the mixing takes place at a temperature above the operative glass transition temperature of the polymer particles and under a condition where ##EQU31## where γ
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1-3 is the interfacial energy of the first particle surface/liquid interfaceγ
1-2 is the interfacial energy of the first particle surface/polymer particle interfaceγ
2-3 is the interfacial energy of the polymer particle surface/liquid interfacevp and vc represent the relative volumes of, respectively, the average polymer particle and the average first particle with vp +vc =1and where the first particles are able to make contact with the surfaces of the polymer particles so that when contact occurs between first particles and polymer particles, composite particles are produced as a dispersion in the liquid phase, the composite particles having ionic and/or stearic colloidal stability against particle-particle flocculation and agglomeration.
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Accused Products
Abstract
A process for the preparation of composite particle dispersons is disclosed. The composite particles have a core particle 1 surrounded by a second material 2. Normally a core shell particle will be formed and the second material which forms the shell will be a polymer material.
The composite particles are formed by mixing a dispersion of polymer particles with pre-formed core material particles. The polymer particles are stabilized relative to one another, and the core material particles are destabilized in the dispersion so that they are able to make contact with the surfaces of the polymer particles. The process takes place at a temperature above the operative glass transition temperature of the polymer, and in the process the polymer spreads over the surface of the core particle so that the core particle is encapsulated.
The process will proceed, and composite particles will be formed, when the interfacial energies of the three interfaces (core/polymer: core/liquid: polymer/liquid) and the relative volumes of the core particles and polymer particles are related to one another in accordance with an equation which is set out in the specification.
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Citations
28 Claims
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1. A process for preparing a dispersion of composite particles, which process comprises mixing first particles with a liquid dispersion of polymer particles, the polymer particles being ionically and/or sterically colloidally stable against particle-particle flocculation and agglomeration, wherein the mixing takes place at a temperature above the operative glass transition temperature of the polymer particles and under a condition where ##EQU31## where γ
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1-3 is the interfacial energy of the first particle surface/liquid interface
γ
1-2 is the interfacial energy of the first particle surface/polymer particle interfaceγ
2-3 is the interfacial energy of the polymer particle surface/liquid interfacevp and vc represent the relative volumes of, respectively, the average polymer particle and the average first particle with vp +vc =1 and where the first particles are able to make contact with the surfaces of the polymer particles so that when contact occurs between first particles and polymer particles, composite particles are produced as a dispersion in the liquid phase, the composite particles having ionic and/or stearic colloidal stability against particle-particle flocculation and agglomeration. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27)
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1-3 is the interfacial energy of the first particle surface/liquid interface
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28. A process for preparing a dispersion of composite particles in a liquid phase, the composite particles being stable against flocculation and aggregation, which process comprises mixing first particles, which particles are not stable against flocculation and aggregation in the process, with a liquid dispersion of polymer particles where the polymer particles are stable against flocculation and aggregation;
- wherein the mixing takes place at a temperature above the operative glass transition temperature of the polymer particles and where
space="preserve" listing-type="equation">θ
.sub.p <
90°and ##EQU33## where vp and vc represent the relative volumes of, respectively, the average polymer particle and the average average first particle, with vp +vc =1 and where p is the contact angle made by the material of the polymer particles in an environment of the liquid phase at a surface which has the surface composition of the first particles.
- wherein the mixing takes place at a temperature above the operative glass transition temperature of the polymer particles and where
Specification