EP0267726A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Coreshell particle dispersions
Assignee: Rohm and Haas Co
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Filing: 1987-11-03
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Granted: —
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Expires: 2007-11-03
Abstract
Abstract An aqueous dispersion of water-insoluble core-shell particles is prepared by emulsion polymerization for use as an opacifying agent in coatings. The particles have interior cores which are swollen with nonaqueous solvent. The polymeric exterior shells have a glass transition temperature greater than about 50°C in the presence of the nonaqueous solvent. The partition coefficient for the nonaqueous solvent between the interior core polymer phase and the exterior shell polymer phase is at least about 1.25. Coatings compositions formulated using the core-shell particles show increased opacity, as single light scattering microvoids are formed in individual particles when the solvent evaporates and the core collapses inside the rigid exterior shell. Opacity develops even when aqueous coatings containing the particles are dried under high humidity conditions.
Inventors
- 👤 Martin Vogel
- 👤 Alexander Kowalski
- 👤 Joseph David Scott
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-06 16:28
CPC Classifications
C; C09; C09D; C09D151/00; C09D151/003; C08; C08F; C08F265/00; C08F265/04; C08F291/00; C09D5/00; C09D7/00; C09D7/40; C09D7/65; C09D7/70; C08L; C08L2205/00; C08L2205/14; C08L2205/18; C08L2205/20
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
107 words
A process for preparing an aqueous dispersions of water-insoluble core-shell particles, having an interior core and an exterior shell, suitable for opacifying coatings, comprising: (a) forming solvent-swellable core particles by emulsion polymerizing at leas one ethylenically unsaturated polymerizable monomer in an aqueous medium; (b) swelling the cores with nonaqueous solvent; and (c) forming polymeric shells around the core particles by emulsion polymerizing at least one ethylenically unsaturated polymerizable monomer; wherein the glass transition temperature of the polymeric shells around the swollen cores is at least 50°C and the partition coefficient of the nonaqueous solvent between the core and shell is at least 1.25, preferably at least 1.50.
Claim 2
Dependent Claim
107 words
A process for preparing an aqueous dispersions of water-insoluble core-shell particles, having an interior core and an exterior shell, suitable for opacifying coatings, comprising: (a) forming solvent-swellable core particles by emulsion polymerizing at leas one ethylenically unsaturated polymerizable monomer in an aqueous medium; (b) swelling the cores with nonaqueous solvent; and (c) forming polymeric shells around the core particles by emulsion polymerizing at least one ethylenically unsaturated polymerizable monomer; wherein the glass transition temperature of the polymeric shells around the swollen cores is at least 50°C and the partition coefficient of the nonaqueous solvent between the core and shell is at least 1.25, preferably at least 1.50.
Claim 3
Dependent Claim
25 words
A process according to claim 1, wherein the core particles are swollen with the nonaqueous solvent before the shells are polymerized on the core particles.
Claim 4
Dependent Claim
39 words
A process according to claim 1 or claim 2, wherein the average polarity of the polymeric shells is greater than the average polarity of the unswollen polymer core particles, and the core particles are swollen with a nonpolar solvent.
Claim 5
Dependent Claim
35 words
A process according to any one of claims 1 to 3, wherein the exterior shells are polymerized from monomer including at least one multi-ethylenically unsaturated monomer and the polymer of the exterior shell is crosslinked.
Claim 6
Dependent Claim
33 words
A process according to any one of the preceding claims, wherein the nonaqueous solvent is selected from the aliphatic hydrocarbons and mixtures thereof, preferably being one or more of isooctane, n-pentane and hexane.
Claim 7
Dependent Claim
68 words
A process according to any one of the preceding claims, wherin the process further comprises polymerizing at least one intermediate shell around the core particles by emulsion polymerizing at least one ethylenically unsaturated monomer subsequent to polymerization of the core particles and prior to the polymerization of the exterior shells, the intermediate shell preferably being more polar than the interior cores and the exterior shells of the particles.
Claim 8
Dependent Claim
36 words
A process according to any one of the preceding claims, wherein the process further comprises forming an additional shell having a glass transition temperature less than the 50°C onto the exterior shell of the core-shell particles.
Claim 9
Dependent Claim
38 words
A process as claimed in any one of the preceding claims, wherein the process further comprises isolating the core-shell particles from the dispersion and then drying the particles such that microvoids are formed and retained in the particles.
Claim 10
Dependent Claim
32 words
Use of the dispersion formed by the process as claimed in any one of claims 1 to 7 or the particles formed by the process of claim 8 in a coating composition.
References Cited (Backward Citations)
No citation records indexed.
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