Composition and process for the sealing of microcups in roll-to-roll display manufacturing

• US 20020188053A1
• Filed: 06/04/2001
• Published: 12/12/2002
• Est. Priority Date: 06/04/2001
• Status: Abandoned Application

• Current Assignee: SiPix Imaging, Inc. (E Ink Holdings Incorporated)
• Original Assignee: SiPix Imaging, Inc. (E Ink Holdings Incorporated)
• Inventors: Liang, Rong-Chang, Wang, Xiaojia, Zang, HongMei
• Application Number:
  US09/874,391
• Publication Number:
  US 20020188053A1
• Time in Patent Office: Days
• US Class Current: 524/474
• CPC Class Codes: C09J 153/00 Adhesives based on block copolymers containing at least one sequence of a polymer obtained by reactions only involving carbon-to-carbon unsaturated bonds; Adhesives based on derivatives of such polymers
• CPC Class Codes: G02F 1/133377 Cells with plural compartments or having plurality of liquid crystal microcells partitioned by walls, e.g. one microcell per pixel
• CPC Class Codes: G02F 1/1334 based on polymer dispersed liquid crystals, e.g. microencapsulated liquid crystals
• CPC Class Codes: G02F 1/1341 Filling or closing of cells
• CPC Class Codes: G02F 1/1347 Arrangement of liquid crystal layers or cells in which the final condition of one light beam is achieved by the addition of the effects of two or more layers or cells
• CPC Class Codes: G02F 1/13475 in which at least one liquid crystal cell or layer is doped with a pleochroic dye, e.g. GH-LC cell G02F1/13476 takes precedence
• CPC Class Codes: G02F 1/167 by electrophoresis
• CPC Class Codes: G02F 1/1679 Gaskets; Spacers; Sealing of cells; Filling or closing of cells

Abstract

The invention relates to a novel sealing composition for the manufacture of an electrophoretic or liquid crystal display, and a sealing process using the composition. The composition allows electrophoretic or liquid crystal cells to be seamlessly sealed and the sealing layer free of any defects.

Claims

1. A composition suitable for sealing electrophoretic cells, which composition comprises:

a) a solvent or solvent mixture which is immiscible with the display fluid contained within the cells and exhibits a specific gravity less than that of the display fluid, and

b) a thermoplastic elastomer.

2. The composition of claim 1 wherein said solvent or solvent mixture has a surface tension of lower than 35 dyne/cm.

3. The composition of claim 2 wherein said solvent or solvent mixture has a surface tension of lower than 30 dyne/cm.

6. The composition of claim 1 wherein said thermoplastic elastomer is selected from a group consisting of ABA and (AB)n types of di -block, tri-block and multi-block copolymers, in which:

A is styrene, α

-methylstyrene, ethylene, propylene or norbonen e,

B is butadiene, isoprene, ethylene, propylene, butylene, dimethylsiloxane or propylene sulfide, and A and B are not the same, and

n is≧

1.

7. The composition of claim 6 wherein n is 1-10.

8. The composition of claim 6 wherein said thermoplastic elastomer is poly(styrene-b-butadiene), (poly(styrene-b-butadiene-b-styrene), poly(styrene-b-isoprene-b-styrene), poly(styrene-b-ethylene/butylenes-b-styrene), poly(styrene-b-dimethylsiloxane-b-styrene), poly((α

-methylstyrene-b-isoprene), poly(α

-methylstyrene-b-isoprene-b-α

-methylstyrene), poly(α

-methylstyrene-b-propylene sulfide-b-α

-methylstyrene), poly((α

-methylstyrene-b-dimethylsiloxane-b-α

-methylstyrene), and their grafted co-polymers and derivatives thereof.

9. The composition of claim 1 wherein the thermoplastic elastomer is poly(ethylene-co-propylene-co-5-methylene-2-norbomene), (ethylene-propylene-diene terpolymer), and their grafted co-polymers and derivatives thereof.

10. The composition of claim 1, further comprising a thermoplastic material that is compatible with one of the blocks of the thermoplastic elastomer.

11. The composition of claim 10 wherein the thermoplastic material is selected from the group consisting of polystyrene and poly ((α

-methylstyrene).

12. The composition of claim 1, further comprising a wetting agent.

13. The composition of claim 12 wherein said wetting agent is selected from a group consisting of surfactants, ZONYL fluorosurfactants, fluoroacrylates, fluoromethacrylates, fluoro-substituted long chain alcohols, perfluoro-substituted long chain carboxylic acids, SILWET silicone surfactants and their derivatives.

14. The composition of claim 1, further comprising one or more of the following agents:

a crosslinking agent, a vulcanizer, a multifunctional monomer or oligomer, a thermal initiator or a photoinitiator.

15. The composition of claim 14 wherein said crosslinking agent is a bisazide such as 4,4′

-diazidodiphenylmethane, or 2,6-di-(4′

-azidobenzal)-4-methylcyclohexanone), and said vulcanizer is a disulfide such as 2-benzothiazolyl disulfide, or tetramethylthiuram disulfide.

17. The process of claim 16, further comprising exposing the sealing layer to UV radiation or thermal baking.

18. The process of claim 16 wherein said solvent or solvent mixture has a surface tension of lower than 35 dyne/cm.

19. The process of claim 18 wherein said solvent or solvent mixture has a surface tension of lower than 30 dyne/cm.

20. The process of claim 16 wherein said solvent or solvent mixture is selected from a group consisting of alkanes, cyclic alkanes, alkylbenzenes, alkyl esters and C_3-5 alkyl alcohols.

21. The process of claim 20 wherein said solvent is heptane, octane, nonane, cyclohexane, decalin, toluene, xylene, and their isomers, and mixtures thereof.

22. The process of claim 16 wherein said thermoplastic elastomer is selected from a group consisting of ABA and (AB)n types of di-block, tri-block and multi-block copolymers, in which:

A is styrene, α

-methylstyrene, ethylene, propylene or norbonene,

B is butadiene, isoprene, ethylene, propylene, butylene, dimethylsiloxane or propylene sulfide, and A and B are not the same, and

n is≧

1.

23. The process of claim 22 wherein n is 1-10.

24. The process of claim 16 wherein said thermoplastic elastomer is poly(styrene-b-butadiene), (poly(styrene-b-butadiene-b-styrene), poly(styrene-b-isoprene-b-styrene), poly(styrene-b-ethylene/butylenes-b-styrene), poly(styrene-b-dimethylsiloxane-b-styrene), poly(α

-methylstyrene-b-isoprene), poly(α

-mthylstyrene-b-isoprene-b-α

-methylstyrene), poly(α

-methylstyrene-b-propylene sulfide-b-α

-methylstyrene), poly(α

-methylstyrene-b-dimethylsiloxane-b-α

-methylstyrene), and their grafted co-polymers and derivatives thereof.

25. The process of claim 16 wherein the thermoplastic elastomer is poly(ethylene-co-propylene-co-5-methylene-2-norbornene), (ethylene-propylene-diene terpolymer), and their grafted co-polymers and derivatives thereof.

26. The process of claim 16, further comprising a thermoplastic material that is compatible with one of the blocks of the thermoplastic elastomer.

27. The process of claim 26 wherein the thermoplastic material is selected from the group consisting of polystyrene and poly ((α

-methylstyrene).

28. The process of claim 16, further comprising a wetting agent.

29. The process of claim 28 wherein said wetting agent is selected from a group consisting of surfactants, ZONYL fluorosurfactants, fluoroacrylates, fluoromethacrylates, fluoro-substituted long chain alcohols, perfluoro-substituted long chain carboxylic acids, SILWET silicone surfactants and their derivatives.

30. The process of claim 16, further comprising one or more of the following agents:

a crosslinking agent, a vulcanizer, a multifunctional monomer or oligomer, a thermal initiator or a photoinitiator.

31. The process of claim 30 wherein said crosslinking agent is a bisazide such as 4,4′

-diazidodiphenylmethane, or 2,6-di-(4′

-azidobenzal)-4-methylcyclohexanone), and said vulcanizer is a disulfide such as 2-benzothiazolyl disulfide, or tetramethylthiuram disulfide.

4. The composition of claim I wherein said solvent or solvent mixture is selected from a group consisting of alkanes, cyclic alkanes, alkylbenzenes, alkyl esters and C_3-5 alkyl alcohols.

5. The composition of claim 4 wherein said solvent is heptane, octane, nonane, cyclohexane, decalin, toluene, xylene, and their isomers, and mixtures thereof.

16. A sealing process for the preparation of electrophoretic display, which process comprises:

a) filling an array of microcups with an electrophoretic fluid;

b) overcoating the electrophoretic fluid with a sealing composition comprising;

a solvent or solvent mixture which is immiscible with the display fluid contained within the cells and exhibits a specific gravity less than that of the display fluid,

thermoplastic elastomer; and

c) allowing the sealing composition to dry to form a sealing layer.