Polymer coated pigment particles and a process for their preparation

• US 3,897,586 A
• Filed: 08/04/1972
• Issued: 07/29/1975
• Est. Priority Date: 08/05/1970
• Status: Expired due to Term

• Current Assignee: James Newton Coker
• Original Assignee: James Newton Coker
• Inventors: Coker, James Newton
• Primary Examiner(s): Martin, William D.
• Assistant Examiner(s): Konopacki, Dennis C.
• Application Number:
  US05/277,883
• Time in Patent Office: 1,089 Days
• Field of Search: 117/1B,1S,161UB,161UC,161UF,161UH
• US Class Current: 428/403
• CPC Class Codes: C01P 2004/32 Spheres
• CPC Class Codes: C01P 2004/50 Agglomerated particles
• CPC Class Codes: C01P 2004/61 Micrometer sized, i.e. from 1-100 micrometer
• CPC Class Codes: C01P 2004/62 Submicrometer sized, i.e. from 0.1-1 micrometer
• CPC Class Codes: C01P 2004/80 Particles consisting of a mixture of two or more inorganic phases
• CPC Class Codes: C01P 2006/90 Other properties not specified above
• CPC Class Codes: C08F 2/44 Polymerisation in the presence of compounding ingredients, e.g. plasticisers, dyestuffs, fillers
• CPC Class Codes: C08F 292/00 Macromolecular compounds obtained by polymerising monomers on to inorganic materials
• CPC Class Codes: C09C 3/10 Treatment with macromolecular organic compounds C09C3/006 takes precedence
• CPC Class Codes: Y10T 428/2991 Coated
• CPC Class Codes: Y10T 428/2993 Silicic or refractory material containing [e.g., tungsten oxide, glass, cement, etc.]
• CPC Class Codes: Y10T 428/2998 including synthetic resin or polymer

Abstract

The deposition of polymers as thin coatings on finely divided pigment particles is accomplished by polymerizing at least one ethylenically unsaturated monomer precursor in the presence of the pigment particles without the presence of a surface-active agent. The process is made feasible through the use of a reaction medium capable of dissolving the monomer reactants but incapable of dissolving the derived polymer. A variety of coated products are prepared indicating the general nature of the process both from the standpoint of type of polymer which can be deposited and also the type of inorganic substrate which can be used.

Claims

1. A PROCESS FOR PREPARING POLYMER-COATED FINELY DIVIDED INORGANIC PARTICLES WHICH COMPRISES SUSPENDING FINELY DIVIDED HYDROPHILIC INORGANIC PARTICLES SELECTED FROM THE GROUP CONSISTING OF METAL OXIDES, CLAY, COLLOIDAL SILICA, AND ZINC CHROMATE IN A NON-AQUEOUS LIQUID REACTION MEDIUM SELECTED FROM THE GROUP CONSISTING OF ALUPHATIC HYDROCARBONS AND CYCLOHEXANE WITHOUT THE PRESENCE OF A SURFACE-ACTIVE AGENT, ADDING POLYMERIZABLE ETHYLENICALLY UNSATURATED MONOMER SELECTED FROM THE GROUP CONSISTING OF ACRYLIC ESTERS, METHACRYLIC ESTERS, VINYL ESTERS, VINYL HALIDES, VINYLIDENE HALIDES, ACRYLIC ACID, AND METHACRYLIC ACID AND A FREE-RADICAL INITIATOR TO THE MEDIUM AT A RATE WHICH APPROXIMATES THE RATE OF POLYMERIZATION, AND POLYMERIZING THE MONOMER IN SITU ONTO THE PARTICLES UNTIL A POLYMER LOADING OF AT LEAST ABOUT 0.5 WEIGHT PERCENT IS REACHED, SAID LIQUID REACTION MEDIUM BEING A SOLVENT FOR THE MONOMER AND INITIATOR AND A NON-SOLVENT FOR THE POLYMER FORMED AS A COATING ON THE PARTICLES.

2. The process of claim 1 wherein the finely divided hydrophilic inorganic particles are acicular pigments.

3. The process of claim 1 wherein the finely divided hydrophilic inorganic particles are metal oxides selected from the group consisting of titanium dioxide, antimony oxide and zinc oxide.

4. The process of claim 1 wherein the liquid reaction medium is a straight chain aliphatic hydrocarbon.

5. The process of claim 1 wherein the liquid reaction medium is hexane or heptane.

6. The process of claim 5 wherein said monomer is methyl methacrylate, ethyLene glycol dimethacrylate, ethylhexyl acrylate, ethyl acrylate, vinyl acetate, vinyl chloride, vinylidene chloride, acrylic acid or methacrylic acid.

7. The process of claim 6 wherein the free-radical initiator is an organic peroxide or azo compound.

8. The process of claim 7 wherein the free-radical initiator is Alpha , Alpha '"'"''"'"'-azobisisobutyronitrile, benzyl peroxide or t-butyl peroxypivalate.

9. The process of claim 8 wherein said monomer is a mixture of methyl methacrylate, ethyl acrylate, and methacrylic acid.

10. The process of claim 1 wherein the liquid reaction medium is an aliphatic hydrocarbon, the free-radical initiator is selected from the group consisting of organic peroxides and azo compounds, and the monomer is polymerized onto the particles until a polymer loading of from about 1.5 to 80 weight percent is reached.

11. The process of claim 10 wherein said liquid reaction medium is a non-polar straight chain aliphatic hydrocarbon and said monomer is polymerized onto the particles until a polymer loading of at least about 3 weight percent is reached.

12. The process of claim 11 wherein said aliphatic hydrocarbon is hexane or heptane and said ethylenically unsaturated monomer is methyl methacrylate, ethylhexyl acrylate, ethyl acrylate, ethylene glycol dimethacrylate, vinyl acetate, vinyl chloride, vinylidene chloride, acrylic acid or methacrylic acid.

13. The product prepared by the process of claim 1.

14. The product prepared by the process of claim 12.