Polymer encapsulation of high aspect ratio materials and methods of making same

• US 7,470,732 B2
• Filed: 10/26/2007
• Issued: 12/30/2008
• Est. Priority Date: 01/23/2003
• Status: Expired due to Fees

• Current Assignee: Sabic Innovative Plastics IP BV (Government of Saudi Arabia)
• Original Assignee: Sabic Innovative Plastics IP BV (Government of Saudi Arabia)
• Inventors: Colborn, Robert Edgar, Steiger, Daniel, Seker, Fazila, Hartshorn, Chris, Acar, Ali Ersin, Hobbs, Stanley Young, van Hamersveld, Eelco M. S.
• Primary Examiner(s): McClendon; Sanza L
• Application Number:
  US11/924,867
• Publication Number:
  US 20080051491A1
• Time in Patent Office: 431 Days
• Field of Search: 428/402, 428/402.24, 428/404, 428/405, 428/406, 428/407, 428/403, 523/200, 523/201, 523/205, 523/210, 523/202, 106/31.13, 106/31.6, 106/31.65
• US Class Current: 523/205
• CPC Class Codes: B01J 13/14 Polymerisation; cross-linking
• CPC Class Codes: C01P 2002/88 by thermal analysis data, e.g. TGA, DTA, DSC
• CPC Class Codes: C01P 2004/02 obtained by optical microscopy
• CPC Class Codes: C01P 2004/20 extending in two dimensions, e.g. plate-like
• CPC Class Codes: C01P 2004/32 Spheres
• CPC Class Codes: C01P 2004/54 Particles characterised by their aspect ratio, i.e. the ratio of sizes in the longest to the shortest dimension
• CPC Class Codes: C08K 9/04 Ingredients treated with organic substances treated with macromolecular compounds C08K9/08
• CPC Class Codes: C08K 9/10 Encapsulated ingredients
• CPC Class Codes: C09B 67/0097 Dye preparations of special physical nature; Tablets, films, extrusion, microcapsules, sheets, pads, bags with dyes
• CPC Class Codes: C09C 1/00 Treatment of specific inorganic materials other than fibrous fillers tenebrescent materials C09K9/00; luminescent materials C09K11/00; Preparation of carbon black
• CPC Class Codes: C09C 1/0015 Pigments exhibiting interference colours, e.g. transparent platelets of appropriate thinness or flaky substrates, e.g. mica, bearing appropriate thin transparent coatings
• CPC Class Codes: C09C 1/0018 uncoated and unlayered plate-like particles
• CPC Class Codes: C09C 1/0021 comprising a core coated with only one layer having a high or low refractive index
• CPC Class Codes: C09C 1/28 Compounds of silicon C09C1/0009, C09C1/0015, C09C1/0078 take precedence
• CPC Class Codes: C09C 1/3063 Treatment with low-molecular organic compounds
• CPC Class Codes: C09C 1/62 Metallic pigments or fillers C09C1/0015 takes precedence
• CPC Class Codes: C09C 1/627 Copper
• CPC Class Codes: C09C 1/64 Aluminium
• CPC Class Codes: C09C 1/644 treated with organic compounds, e.g. polymers
• CPC Class Codes: C09C 2200/1004 the core comprising at least one inorganic oxide, e.g. Al2O3, TiO2 or SiO2
• CPC Class Codes: C09C 2200/102 : the core consisting of glass or silicate material like mica or clays, e.g. kaolin
• CPC Class Codes: C09C 2200/1025 : comprising at least one metal layer adjacent to core material, e.g. core-M or M-core-M
• CPC Class Codes: C09C 2200/403 : Low molecular weight materials, e.g. fatty acids
• CPC Class Codes: C09C 2200/404 : comprising additional functional groups, e.g. -NH2, -C=C- or -SO3
• CPC Class Codes: C09C 2200/405 : High molecular weight materials, e.g. polymers
• CPC Class Codes: C09C 3/08 : Treatment with low-molecular-weight non-polymer organic compounds C09C3/006, C09C3/048 take precedence
• CPC Class Codes: C09C 3/10 : Treatment with macromolecular organic compounds C09C3/006 takes precedence
• CPC Class Codes: Y10T 428/2982 : Particulate matter [e.g., sphere, flake, etc.]
• CPC Class Codes: Y10T 428/2989 : Microcapsule with solid core [includes liposome]
• 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 428/2995 : Silane, siloxane or silicone coating
• CPC Class Codes: Y10T 428/2996 : Glass particles or spheres
• CPC Class Codes: Y10T 428/2998 : including synthetic resin or polymer

Abstract

A pigment contains one or more substantially spherical-shaped beads. Each substantially spherical-shaped bead includes one or more high aspect ratio particles encapsulated within an encapsulating material. Resinous compositions containing this pigment and a plastic, for example a polycarbonate, have a flowline-free colored, sparkling and/or metallescent appearance.

Claims

1. A method of preparing an encapsulated pigment composition via suspension polymerization, the encapsulated pigment composition comprising one or more substantially spherical-shaped beads, wherein the substantially spherical-shaped beads comprise one or more high aspect ratio particles encapsulated within an encapsulating material, the method comprising the steps of:

dispersing high aspect ratio particles in at least one of a monomer or a polymer and a cross-linking agent to form a suspension mixture;

adding the suspension mixture to an aqueous mixture comprising a suspension agent;

heating and mixing the aqueous reaction mixture to encourage the formation of substantially spherical-shaped beads, wherein most of the substantially spherical-shaped beads encapsulate one or more high aspect ratio particles to an extent that the high aspect ratio particles will not become delaminated during processing;

quenching the aqueous reaction mixture after the substantially spherical-shaped beads are formed; and

collecting the substantially spherical-shaped beads.

2. The method of claim 1, further comprising the step of:

suspending the one or more high aspect ratio particles in the suspension mixture by sonicating the suspension mixture prior to adding the suspension mixture to the aqueous reaction mixture.

3. The method of claim 1, the method further comprising utilizing at least one of gravity sedimentation and centrifugation to separate the substantially spherical-shaped beads into various batches.

4. The method of claim 3, wherein the gravity sedimentation comprises:

a) reslurrying the substantially spherical-shaped beads in a slurry solution to form a separation system having an original volume;

b) mixing the separation system;

c) allowing the separation system to stand still to come to equilibrium;

d) removing a fraction of useable substantially spherical-shaped beads from the separation system;

e) filtering the fraction of useable substantially spherical-shaped beads that is obtained from the separation system;

f) washing the filtered fraction of useable substantially spherical-shaped beads to remove any excess slurry solution; and

g) adding a quantity of deionized water to the remaining substantially spherical-shaped beads and slurry solution in the separation system to bring the volume of the separation system back to the original volume; and

h) repeating steps b)-g) as necessary until all the substantially spherical-shaped beads have been removed from the separation system.

5. The method of claim 4, further comprising drying the substantially spherical-shaped beads.

6. The method of claim 5, further comprising utilizing the substantially spherical-shaped beads in a resinous composition.

7. The method of claim 1, wherein the pigment further comprises at least one member selected from the group consisting of:

colorants, thermal stabilizers, oxidation inhibitors, butylated hvdroxytoluene (BHT), radical scavengers, a vinyl-based monomer, filler, impact modifiers, UV absorbers, and fire retardants.

8. The method of claim 1, wherein the high aspect ratio particles comprise at least one of:

aluminum, gold, silver, copper, nickel, titanium, stainless steel, nickel sulfide, cobalt sulfide, manganese sulfide, metal oxides, white mica, black mica, synthetic mica, mica coated with titanium dioxide, metal-coated glass flakes, or colorants.

9. The method of claim 1, wherein the suspension mixture comprises at least one of:

styrene, methyl methacrylate, styrene acrylonitrile, divinylbenzene, or modified bisphenol A.

10. The method of claim 1, wherein the cross-linking agent is present in an amount from 0.175 to 0.25 parts per hundred in the aqueous mixture.

11. The method of claim 1, wherein the cross-linking agent is present in an amount of 0.20 parts per hundred parts in the aqueous mixture.

12. The method of claim 1, further comprising the step of screening the collected substantially spherical-shaped beads produced to obtain a composition wherein the substantially spherical-shaped beads have an average diameter of 75 to 125 microns.

13. The method of claim 12 wherein the substantially spherical-shaped beads are screened to have a maximum diameter of 150 microns.