Composite particles for toner additives
AssigneeCabot Corporation
InventorsHairuo Tu, Jincheng Xiong, Paul S. Palumbo, Dmitry Fomitchev
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Abstract
Metal oxide-polymer composite particles have a median particle size D50 of 40-75 nm or 100-150 nm and an average RTA of at least 0.06. Alternatively or in addition, metal oxide-polymer composites comprise two or more populations of metal oxide particles differing in size, particle size distribution, or shape. Alternatively or in addition, the use of a multicomponent hydrophobizing system including an alkylsilane to fabricate metal oxide-polymer composite particles increases the tribocharge of the composite particles.
Claims20
Silica-polymer composite particles in powder form comprising a plurality of silica particles and a polymer matrix, wherein:
- the plurality of silica particles comprises at least a first population of silica particles and a second population of silica particles, the first population of silica particles having a different size, shape, or particle size distribution with respect to the second population;
- the silica particles are surface-modified with a first hydrophobizing system comprising a bifunctional component via which the silica particles are covalently attached to the polymer matrix,
- at least a portion of the plurality of silica particles project into and out from the polymer matrix,
- the polymer matrix comprises a polymer or copolymer of the first hydrophobizing system, and
- the silica-polymer composite particles have an average SF-1 from 110 to 185 and an average RTA from 0.06 to 0.19.
A method of producing a silica-polymer composite particle, comprising:
- preparing an aqueous dispersion comprising a first hydrophobizing system in an aqueous medium and at least a first population of silica particles and a second population of silica particles, the first population of silica particles having a different size, shape, or particle size distribution than the second population, wherein the first hydrophobizing system comprises a bifunctional component having the formula [R33-x(OR1)x]SiR2Q, where x is 1, 2, or 3, R1 is methyl or ethyl, R2 is an alkyl linker with the general formula CnH2n, where n=1-10, R3 is methyl or ethyl and Q is a substituted or unsubstituted vinyl, acrylate ester, or methacrylate ester group, with the proviso that when Q is substituted or unsubstituted vinyl, n is 2-10;
- incubating the dispersion for a predetermined amount of time;
- adding a radical initiator to the dispersion;
- allowing a chemical group of the first hydrophobizing system to become part of a polymer, thereby forming silica-polymer composite particles having an average SF-1 from about 110 to about 185 and an average RTA from about 0.06 to about 0.19;
- and
- drying the silica-polymer composite particles to obtain a powder.
Dependencies are inferred from the claim text.