Polymeric Opacifier

Summary:
This invention relates to polymer technology. More particularly, this invention relates to polymer particles for use in paint compositions or other applications, paint compositions containing the polymer particles, a method of manufacturing polymer particles for use in a paint composition, and a method of making such a paint composition.

Full Description:
Broadly, according to one aspect of the invention there is provided a method of controlling micro-structural and chemical aspects of polymeric particles using any one or more active species selected from the group consisting of: chain transfer agents; functional monomers; functional additives; initiators; and functional pre-polymers.

More specifically, according to one aspect of the invention there is provided a method of producing polymer particles, the invention including the steps of:
providing at least one or more water-insoluble phases;
adding to the at least one water-insoluble phase at least one water-soluble resin or additive with chemical functionality;
admixing at least one initiator and/or chain transfer agent with or without chemical functionality;
emulsifying at least one water-soluble phase in the water-insoluble phase by the addition of a suitable emulsifier or emulsifiers to the water-insoluble phase;
dispersing the at least one water-insoluble phase in an aqueous phase using a suitable water-in-oil dispersant; and
allowing the resulting emulsion to cure, thereby to render polymer particles.

In the context of this invention a “phase” may be defined as consisting of a resin or polymer either in a suitable solvent or in a liquid physical phase, or as a solvent, monomer(s) or various combinations of polymer/resin dissolved in solvents or monomers or monomers mixed with solvents to provide a phase that differs in solubility, such as being insoluble in an aqueous phase.

An aqueous phase may be defined in the context of this invention to be water or a water-derived solution such as water with dissolved salts or other substances that are essentially water-soluble.

The dispersant may include any of the many examples of dispersants including, but not limited to, surfactants such as the range of Span, Tween or Brij surfactants with suitable hydrophilic-lypophilic balances (hlb).

The oil-in-water dispersant used in this invention may consist of any suitable dispersant that has the ability to disperse liquids or solids in water. Examples include poly(vinyl alcohol), modified cellulose such as hydroxyethyl cellulose, gum Arabic, starch and modified starches or poly(vinyl alcohol) and sodium lauryl sulphate or any suitable dispersant or dispersant combinations and surfactant combinations that may be employed to establish stable dispersions.

At least one water-soluble polymer may be emulsified in the resin. Suitable examples include but are not limited to poly(acrylic acid), poly(methacrylic acid), poly(lactic acid) or any suitable polymeric, macromolecular or molecular material that can be synthesised by means of addition polymerization, ring-opening polymerization, esterification or amidation reactions.

The water-insoluble polymer phase dispersed in the aqueous phase may, for example, be an epoxy resin. The saturated or unsaturated epoxy resins may include epoxy resins containing hydroxyl- and/or epoxy functionality or any other suitable chemical functionality such as ester or ether functionality.

The hydroxyl or epoxy functionality may be selected form the group consisting of, but not limited to: urethane-; amine-; hydroxyl-; epoxy-; or any other functionality that may be included in the formulation of a polyurethane known to persons skilled in the art of the invention.

Other examples of functional resins or pre-polymers include functional acrylic resins. The functional acrylic resins may include pre-polymers of acrylic acid and esters thereof. The functional acrylic resins may also include methacrylic acid and esters thereof. These acrylic polymers may also include functionalities such as carboxylic-, hydroxyl-, amine-, epoxy-, mercaptan-, acid- and thioester functionality, either as part of the main polymer chain or as specific end-groups.

A functional resin or pre-polymer may be employed in this invention to add additional functionality to the final product. These polymers or pre-polymers may be added to the oil-phase (resins such as epoxy or polyester resins, or on their own). These functionalized polymers may include any one or more species selected from the group consisting of acrylic monomers or vinyl-group containing monomers such as styrene or allyl alcohol or any monomer or chain transfer agent capable of addition polymerization both through free radical polymerization, ring opening polymerization, polyester formation, polyether formation and polyamide formation;

In addition, other examples of functional resins or pre-polymers may include functionally grafted polyethylene or polypropylene. In one embodiment, the resins or pre-polymers may include a maleic anhydride grafted polypropylene polymer or wax.

Examples of functional monomers that may be employed in this invention include any one or more monomers selected from the group consisting of: 2-hydroxy ethyl acrylate; N,N’-dimethylaminoethyl acrylate; acrylic acid; methacrylic acid; maleic anhydride; maleic acid; fumaric acid; polyethylene glycol acrylate of various molecular weights; dodecyl acrylate; acrylamide; methylolacrylamide; butoxymethyl acrylamide; iso-butoxymethyl acrylamide; glycidyl methacrylate; octadecyl methacrylate; esters of acrylic acid; and methacrylic acid with hydrocarbon chains up to C34H70, and the like.

The water-in-oil emulsifier may be a synthetic wax or non-ionic surfactant. More particularly, the emulsifier may be an ester of sorbitan and stearic acid, such as sorbitan mono-oleate.

Examples of chain transfer agents that may be used to control the polymer microstructure and/or porosity may be any one or more chain transfer agents selected from the group consisting of: thiols, such as butane thiol, decane thiol, dodecane thiol, thioglycolic acid and the like; halogen-containing species, such as carbon tetrachloride, carbon tetrabromide, nonafluoro iodobutane, thio-ester species such as S-(thiobenzoyl)thioglycolic acid; and xanthates, such as sodium ethyl xanthate, or any suitable species that may be used to control molecular mass, commonly known as reversible addition-fragmentation chain transfer (RAFT) agents. Such RAFT agents typically may control molecular mass, crosslink density and aid to provide functionality.

Further examples of chemical agents used to introduce functionality into the final formulation may include functional azo-initiators. Apart from, or in addition to, the functional azo-initiators, other types of initiators may be used, such as functional peroxide or hydroperoxide initiators, such as those commercially available from Akzo-Nobel. These initiators may be water- or oil soluble.

The polymer particles produced in accordance with the method of the invention may find application in paint compositions, powder coating compositions, inks, opacifying agents in paper, and the like, and accordingly the invention extends to the use of the polymer particles of the invention as opacifying agents in paint compositions, powder coating compositions, inks, and paper.

According to another aspect of the invention, there is provided a method of producing a paint composition, the method including the steps of adding the polymer particles of the invention to a paint base. The polymer particles may be added to the paint base in a ratio of between
5 vol% to 25 vol% and preferably in the range of 10 vol% to 25 vol%.

Problem this idea/invention addresses:
This invention reduces or even eliminates the amount of TiO2 used in waterborne paints and coatings

Attached files:
Bead.bmp

Patent: ZA 12,270

Asking price: [CONTACT SELLER]
Available for consultation? Yes

Invention #11742
Date posted: 2012-03-12

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