Structured reactive latex
AssigneeH. B. Fuller Licensing & Financing, Inc.
InventorsYi Wei, Wayne P. Miller, Catherine A. Wenz
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Abstract
A latex comprising a free radically polymerized product, said product comprising at least two ethylenically unsaturated monomers, at least one of said monomers having an isocyanate group which is sterically hindered or blocked and at least one other of said ethylenically unsaturated monomers being free of isocyanate functional groups, in an aqueous emulsion in the presence of a free-radical polymerization catalyst, in a manner such that the sterically hindered or blocked isocyanate groups distribute in the outer layer of the latex particle and the method of making such.
Claims24
A method for the preparation of a structured reactive latex particle comprising the steps of:
- a) providing an aqueous polymer emulsion comprising bulk core particles being free of isocyanate groups wherein said emulsion in a semi-batch starved process comprises the free radical addition polymerization of:
- i) at least one ethylenically unsaturated monomer free of isocyanates;
- ii) at least one emulsifying agent;
- and
- iii) at least one free radical initiator;
- to form a seed particle latex;
- b) copolymerzing at least one ethylenically unsaturated monomer with a sterically hindered isocyanate group, optionally with other ethylenically unsaturated monomer on top of the preformed seed particles to further enlarge the particle size and to form an outer surface layer comprising isocyanate groups thereon onto said bulk core;
- and
- c) completing the free radical addition reaction.
A structured reactive latex suitable for fiberglass sizing, said latex comprising particles having a bulk core surrounded by an outer surface layer;
- wherein the bulk core is free of isocyanates and prepared by semi-batch, starved process comprising the free radical addition polymerization of:
- i) at least one ethylenically unsaturated monomer free of isocyanates;
- ii) at least one emulsifying agent;
- and
- iii) at least one free radical initiator;
- to form a seed particle latex;
- wherein said surface layer comprises isocyanate groups and prepared by free radical polymerization comprising:
- iv) at least one ethylenically unsaturated monomer with a sterically hindered isocyanate group and;
- optionally
- v) at least one or more ethylenically unsaturated monomers;
- and the volume ratio of said bulk core to said surface layer is in a range of from about 5:95 to about 99:1.
A semi-batch, starved method for the preparation of a structured reactive latex particle comprising the steps of:
- a) providing an aqueous polymer pre-emulsion comprising bulk core particles being free of isocyanate groups wherein said emulsion comprises:
- i) at least one ethylenically unsaturated monomer free of isocyanates;
- and
- ii) at least one emulsifying agent;
- b) introducing an entire amount of at least one free radical initiator to a minor portion of the pre-emulsion in a reaction chamber;
- c) conducting the free radical polymerization at a suitable temperature;
- d) continuously feeding a major portion of the pre-emulsion to the reaction chamber;
- e) copolymerizing at least one ethylenically unsaturated monomer comprising a sterically hindered isocyanate with the remaining pre-emulsion and optionally, with at least one ethylenically unsaturated monomer;
- and
- f) completing the free radical polymerization;
- to form a structured reactive latex having a bulk core surrounded by an outer surface layer with isocyanate groups thereon onto said bulk core.
Dependencies are inferred from the claim text.