Method for making materials having uniform limited coalescence domains

• US 6,423,368 B1
• Filed: 01/06/2000
• Issued: 07/23/2002
• Est. Priority Date: 01/06/2000
• Status: Expired due to Term

• Current Assignee: HKC Corporation Limited (Shenzhen Huike Investment Holding Co., Ltd.)
• Original Assignee: Eastman Kodak Company
• Inventors: Boettcher, John W., Stephenson, Stanley W., Giacherio, David J.
• Primary Examiner(s): Talbot, Brian K.
• Application Number:
  US09/478,683
• Time in Patent Office: 929 Days
• Field of Search: 427/123, 427/163.3, 427/163.4, 427/372.2, 427/64
• US Class Current: 427/64
• CPC Class Codes: C09K 19/544 as dispersing or encapsulating medium around the liquid crystal
• CPC Class Codes: G02F 1/1334 based on polymer dispersed liquid crystals, e.g. microencapsulated liquid crystals
• CPC Class Codes: G02F 1/13718 based on a change of the texture state of a cholesteric liquid crystal

Abstract

A light-modulating, electrically responsive sheet including a substrate and an electrically conductive layer formed over the substrate. The sheet further includes, in an aqueous bath, an immiscible, field responsive light-modulating material along with a quantity of colloidal particles wherein the colloidal particles limit coalesced domain size and a binder; blending the constituents of the aqueous bath to form a dispersion of said field-responsive, light-modulating material below a coalescence size which sets to form limited coalescence domains having a uniform size; coating said material over the substrate; and drying said coated material to form a set of uniform domains so that such dispersion coalesces to form a set of uniform limited coalescence domains having a plurality of electrically responsive optical states.

Claims

1. A method of making a polymeric dispersed electrically responsive light-modulating material comprising the steps of:

(a) providing in an aqueous bath an immiscible, field responsive light-modulating material along with a quantity of colloidal particles wherein the colloidal particles limit coalesced domain size and a binder;

(b) blending the constituents of the aqueous bath to form a dispersion of said field-responsive, light-modulating material below a coalescence size which sets to form limited coalescence domains having a ratio of maximum to minimum domain size of less than 2;

1 and having a uniform size;

(c) coating said material onto a substrate; and

(d) drying said coated material to form a set of uniform liquid domains.

6. The method of claim 1 wherein the binder is a dissolved polymer.

7. The method of claim 6 wherein the dissolved polymer is gelatin.

10. The method of claim 1 wherein the colloidal particles are colloidal silica.

12. The method of claim 1 wherein the aqueous bath further contains a promoter material to drive the colloidal particles to the liquid-liquid interface.

13. The method of claim 12 wherein the promoter material is a copolymer of adipic acid and 2-(methylamino)ethanol.

16. A method according to claim 1, wherein domain size is about 2 microns.

2. A method of making a light-modulating, electrically responsive sheet comprising:

(a) providing a substrate;

(b) forming an electrically conductive layer over the substrate;

(c) providing in an aqueous bath an immiscible, field responsive light-modulating material along with a quantity of colloidal particles wherein the colloidal particles limit coalesced domain size and a binder;

(d) blending the constituents of the aqueous bath to form a dispersion of said field-responsive, light-modulating material below a coalescence size which sets to form limited coalescence domains having a uniform size;

(e) coating said material over the substrate; and

(f) drying said coated material to form a set of uniform liquid domains so that such dispersion coalesces to form a set of uniform limited coalescence domains having a ratio of maximum to minimum domain size of less than 2;

1 and having a plurality of electrically responsive optical states.

3. The method of claim 2 wherein the dispersion includes liquid crystal material.

4. The method of claim 3 wherein the dispersion includes cholesteric liquid crystal material.

5. The method of claim 3 wherein the dispersion includes nematic liquid crystal material.

8. The method of claim 2 wherein the binder is a dissolved polymer.

9. The method of claim 8 wherein the dissolved polymer is gelatin.

11. The method of claim 2 wherein the colloidal particles are colloidal silica.

14. The method of claim 2 wherein the aqueous bath further contains a promoter material to drive the colloidal particles to the liquid-liquid interface.

15. The method of claim 14 wherein the promoter material is a copolymer of adipic acid and 2-(methylamino)ethanol.

17. A method according to claim 2, wherein domain size is about 2 microns.