Aggregation processes

• US 5,744,520 A
• Filed: 07/19/1996
• Issued: 04/28/1998
• Est. Priority Date: 07/03/1995
• Status: Expired due to Term

• Current Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Inventors: Veregin, Richard P. N., Patel, Raj D., Kmiecik-Lawrynowicz, Grazyna E., Hopper, Michael A., McDougall, Maria V.
• Primary Examiner(s): Szekely, Peter A.
• Application Number:
  US08/684,955
• Time in Patent Office: 648 Days
• Field of Search: 430/137, 523/332, 523/334, 523/335, 523/339, 523/205, 523/206, 523/215, 523/223, 524/44, 524/45, 524/46, 524/156, 524/430, 524/431, 524/432, 524/406, 524/408, 524/413, 524/503
• US Class Current: 523/334
• CPC Class Codes: C08J 3/215 at least one additive being also premixed with a liquid phase
• CPC Class Codes: G03G 9/1131 Coating methods; Structure of coatings
• CPC Class Codes: G03G 9/1133 obtained by reactions only involving carbon-to-carbon unsaturated bonds
• CPC Class Codes: G03G 9/1138 Non-macromolecular organic components of coatings
• CPC Class Codes: G03G 9/1139 Inorganic components of coatings

Abstract

A process for the preparation of polymer compositions which comprises mixing a conductive component with an anionic polymeric latex containing a polymer; adding a cationic surfactant, or flocculant whereby the aggregation of the latex particles and the conductive component particles results; subsequently adding colloidal stabilizer, followed by the addition of a base to obtain a pH of from about 7 to about 12; heating above about the polymer glass transition temperature thereby enabling the severage, or breakage of the formed aggregated particles; further heating above about the polymer glass transition temperature enabling the coalescence of the polymer and conductive component particles; and optionally washing and drying the resulting coalesced product.

Claims

1. A process for the preparation of polymer compositions which comprises mixing a conductive component with an anionic polymeric latex containing a polymer;

adding a cationic surfactant, or flocculant whereby the aggregation of the latex particles and the conductive component particles results;

subsequently adding colloidal stabilizer, followed by the addition of a base to obtain a pH of from about 7 to about 12;

heating above about the polymer glass transition temperature thereby enabling the severage, or breakage of the formed aggregated particles;

further heating above about the polymer glass transition temperature enabling the coalescence of the polymer and conductive component particles; and

optionally washing and drying the resulting coalesced product.

2. A process in accordance with claim 1 wherein the pH is from about 7 to about 9, and there is formed a conductive polymer with a conductive component dispersed therein.

3. A process in accordance with claim 1 wherein the conductive component is carbon black.

4. A process in accordance with claim 1 wherein the conductive component is carbon black present in an amount of from about 12 to about 40 weight percent based on the weight of the polymer and conductive component.

5. A process in accordance with claim 1 wherein the conductivity of the coalesced polymer product is from about 10^-6 to about 10^-9 ohm^-1 cm^-1.

6. A process in accordance with claim 1 wherein shear is accomplished during and subsequent to adding said cationic surfactant;

the aggregates are from about 5 to about 10 microns in volume average diameter; and

wherein heating the formed aggregates above about the polymer glass temperature at a pH of from about 7 to about 12 causes the severage, or breakage of the aggregated particles to smaller size aggregates of from about 0.5 to about 1 micron in average volume diameter.

7. A process in accordance with claim 1 wherein the polymer with conductive component dispersed therein is of a size of from about 0.5 to about 1 micron in volume average diameter.

8. A process in accordance with claim 1 wherein the temperature of the aggregation is less than the polymer glass transition temperature (Tg), thereby controlling the speed at which particles submicron in size are collected, and wherein there are formed aggregates of from about 5 to about 10 microns.

9. A process in accordance with claim 1 wherein the temperature of the coalescence is above the polymer glass transition temperature thereby controlling the morphology of the polymer particles formed, and which particles are selected as carrier coatings.

10. A process in accordance with claim 1 wherein the time of heating at a temperature above the polymer Tg controls the morphology of the polymer particles formed, and which particles are selected as carrier coatings.

11. A process in accordance with claim 1 wherein spherical conductive polymer carrier coating particles result.

12. A process in accordance with claim 6 wherein the homogenization or shearing is accomplished by homogenizing at from about 1,000 revolutions per minute to about 10,000 revolutions per minute for a duration of from about 1 minute to about 120 minutes.

13. A process in accordance with claim 1 wherein the polymer is selected from the group consisting of poly(methyl-methacrylate), poly(styrene-butadiene), poly(para-methyl styrene-butadiene), poly(meta-methylstyrene-butadiene), poly(alpha-methylstyrene-butadiene), poly(methylmethacrylate-butadiene), poly(ethylmethacrylate-butadiene), poly(propylmethacrylate-butadiene), poly(butylmethacrylate-butadiene), poly(methylacrylate-butadiene), poly(ethylacrylate-butadiene), poly(propylacrylate-butadiene), poly(butylacrylate-butadiene), poly(styrene-isoprene), poly(para-methyl styrene-isoprene), poly(meta-methylstyrene-isoprene), poly(alpha-methylstyrene-isoprene), poly(methylmethacrylate-isoprene), poly(ethylmethacrylate-isoprene), poly(propylmethacrylate-isoprene), poly(butylmethacrylate-isoprene), poly(methylacrylate-isoprene), poly(ethylacrylate-isoprene), poly(propylacrylate-isoprene), and poly(butylacrylate-isoprene).

14. A process in accordance with claim 1 wherein the polymer is a copolymer of poly(methacrylic acid), poly(acrylic acid), poly(itaconic acid), poly(methyl-methacrylate), poly(styrene-butadiene), poly(para-methyl styrene-butadiene), poly(meta-methylstyrene-butadiene), poly(alpha-methylstyrene-butadiene), poly(methylmethacrylate-butadiene), poly(ethylmethacrylate-butadiene), poly(propylmethacrylate-butadiene), poly(butylmethacrylate-butadiene), poly(methylacrylate-butadiene), poly(ethylacrylate-butadiene), poly(propylacrylate-butadiene), poly(butylacrylate-butadiene), poly(styrene-isoprene), poly(para-methyl styrene-isoprene), poly(meta-methylstyrene-isoprene), poly(alpha-methylstyrene-isoprene), poly(methylmethacrylate-isoprene), poly(ethylmethacrylate-isoprene), poly(propylmethacrylate-isoprene), poly(butylmethacrylate-isoprene), poly(methylacrylate-isoprene), poly(ethylacrylate-isoprene), poly(propylacrylate-isoprene), or poly(butylacrylate-isoprene).

15. A process in accordance with claim 1 wherein the conductive component is selected from the group consisting of tin oxide, zinc oxide, ytrium oxide, vanadium oxide, tungsten oxide, nickel oxide, cobalt oxide, cesium oxide, titanium oxide, and mixtures thereof.

16. A process in accordance with claim 1 wherein the anionic polymeric latex contains an anionic surfactant selected from the group consisting of sodium dodecyl sulfate, sodium dodecylbenzene sulfate and sodium dodecylnaphthalene sulfate.

17. A process in accordance with claim 1 wherein the colloidal stabilizer is selected from the group consisting of anionic surfactants, nonionic surfactants, polyvinyl alcohol, methalose, methyl cellulose, ethyl cellulose, propyl cellulose, hydroxy ethyl cellulose, and carboxy methyl cellulose.

18. A process in accordance with claim 17 wherein the colloidal stabilizer is the anionic surfactant sodium dodecyl sulfate, sodium dodecylbenzene sulfate, or sodium dodecylnaphthalene sulfate;

the nonionic surfactant is polyoxyethylene cetyl ether, polyoxyethylene lauryl ether, polyoxyethylene octyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene oleyl ether, polyoxyethylene sorbitan monolaurate, polyoxyethylene stearyl ether, polyoxyethylene nonylphenyl ether, or dialkylphenoxy poly(ethyleneoxy)ethanol.

19. A process in accordance with claim 1 wherein the polymer is from about 0.01 to about 3 microns in average volume diameter;

and the conductive component particles are from about 0.01 to about 3 microns in volume average diameter.

20. A process in accordance with claim 1 wherein the product of polymer with conductive component is washed with warm water, and the surfactants are removed therefrom, followed by the drying thereof.

21. A process in accordance with claim 1 wherein said heating is from about 5°

to about 50°

C. above the polymer glass transition temperature, or wherein the polymer glass transition temperature, Tg, is from about 50°

to about 100°

C., or the polymer Tg is 54°

C., and heating is from about 59°

to about 104°

C.

22. A process for the preparation of conductive polymer particles which comprises the synthesis, or provision of a submicron anionic polymer latex, and which latex is prepared by batch emulsion polymerization;

dispersing a conductive component submicron in size in the polymer latex;

adding a cationic surfactant, or flocculent with high shear whereby the aggregation of the latex particles and the conductive component results, enabling aggregates of from about 5 to about 10 microns in average volume diameter;

adding a base component to obtain a pH of from about 8 to 12;

heating the formed aggregates above about the polymer Tg, which heating causes the severage, or breakage of the aggregates to smaller aggregates of from about 0.5 to about 1 micron;

further heating above about the polymer Tg to coalesce the polymer and conductive particles;

followed by washing and drying.

23. A process in accordance with claim 22 wherein the base is sodium hydroxide.

24. A process for the preparation of polymer compositions comprising mixing a conductive component with an anionic polymeric latex prepared by emulsion polymerization utilizing anionic surfactants, or a mixture of anionic and nonionic surfactants;

adding a cationic surfactant, or flocculant whereby the aggregation of the latex particles and the conductive particles results;

adding colloidal stabilizer, followed by the addition of an alkali base to obtain a pH of from about 7 to about 12;

heating the formed aggregates above the polymer glass transition temperature thereby enabling the severage, or breakage of the aggregated particles;

heating further above the polymer glass transition temperature enabling the coalescence of the polymer and conductive component particles; and

washing and drying the resulting coalesced product.

25. A process in accordance with claim 24 wherein the nonionic surfactant concentration used in the latex preparation is from about 0.1 to about 5 weight percent;

the anionic surfactant concentration used in the latex preparation is from about 0.1 to about 5 weight percent; and

the cationic surfactant concentration is from about 0.1 to about 5 weight percent.