Connected branch copolymers, methods for their production, and copying materials including same

• US 4,946,824 A
• Filed: 05/24/1989
• Issued: 08/07/1990
• Est. Priority Date: 02/22/1983
• Status: Expired due to Fees

• Current Assignee: Union Carbide Chemicals And Plastics Company, Inc.
• Original Assignee: Union Carbide Chemicals And Plastics Company, Inc.
• Inventors: Meschke, Debra J., Hoy, Kenneth L.
• Primary Examiner(s): Kight, III, John
• Assistant Examiner(s): NOT, DEFINED
• Application Number:
  US07/356,359
• Time in Patent Office: 440 Days
• Field of Search: 503/216, 503/225, 427/150
• US Class Current: 503/216
• CPC Class Codes: C08G 65/04 from cyclic ethers only
• CPC Class Codes: C08G 85/00 General processes for preparing compounds provided for in this subclass

Abstract

Capped connected branch copolymers are provided comprising a core segment, branched polymer segments attached to the core segment, linear polymer segments attached to the terminals of the branched polymer segments, and cap segments, which comprise residues of an alkylene oxide containing at least 4 carbon atoms and which are attached to the free terminals of the linear polymer segments. These capped copolymers are less water-soluble than the uncapped connected branched copolymers from which they are derived, and are useful in carbonless copying systems as carriers for the color precursor microcapsules. The microcapsules can be applied to the carbonless copying sheet by dispersing the microcapsules in the capped copolymer, heating the copolymer above its transition temperature and spreading the melted copolymer over the sheet. After cooling, the copolymer forms a coherent layer on the sheet. Since no water is required for application of the copolymer, the curling and wrinkling problems encountered when using aqueous dispersions of the microcapsules are avoided.

Claims

1. A coated sheet for use in a carbonless copying system, the coated sheet comprising a flat sheet of solid material having first and second flat surfaces on opposed sides thereof, the sheet being capable of receiving impressions on at least part of its first surface and having at least part of its second surface coated with a layer of a color precursor composition comprising a capped connected branch copolymer, which itself comprises:

(A) a core segment having a valence of v, wherein v is an integer, and having correspondingly v terminal bonds connected to;

(B) v polyvalent, non-crosslinked branched polymer segments each having an average of t terminal bonds, wherein t is greater than about two, one of said terminal bonds being connected to said core segment, and each of said branched polymer segments being connected via its remaining (t-1) terminal bonds to

(C) a set of linear polymer segments, with an average of t-1 linear polymer segments per set, to provide a group of about v (t-1) linear polymer segments wherein the linear polymer segments have substantially similar chain lengths and composition within said group, the capped connected branch copolymer having a group of terminal linear polymer segments bearing groups capable of effecting hydrogen bonding and

(D) a set of cap segments connected to terminals of the terminal linear polymer segments which are not connected to the branched polymer segments, each of the cap segments comprising at least one residue of an alkylene oxide containing at least about 4 carbon atoms, there being on average at least about 0.5 of said alkylene oxide residues for each terminal of the terminal linear polymer segments not connected to the branched polymer segments; and

a plurality of microcapsules dispersed in the capped connected branch copolymer, these microcapsules comprising a color precursor.

2. A coated sheet according to claim 1 wherein the capped connected branch copolymer has a transition temperature not in excess of about 70°

C.

3. A coated sheet according to claim 1 wherein, in the capped connected branch copolymer the terminal groups capable of effecting hydrogen bonding comprise carboxylic acid groups, esters, salts or amides of carboxylic acid groups, amino groups, phosphate groups, esters, salts or amides of phosphate groups, hydroxyl groups, or residues of any of such groups remaining after attachment of the cap segments to the terminal linear polymer segments via the terminal groups.

4. A coated sheet according to claim 3 wherein, in the capped connected branch copolymer, the terminal groups capable of effecting hydrogen bonding comprise ether linkages remaining after attachment of the cap segments to the terminal linear polymer segments via terminal hydroxyl groups on the terminal linear polymer segments.

5. A coated sheet according to claim 4 wherein, in the capped connected branch copolymer, the terminal linear polymer segments comprise polyoxyalkylene linear polymer, segments

6. A coated sheet according to claim 1 wherein the core, branched and linear segments provide separate hydrophobic and hydrophilic portions of the polymer.

7. A coated sheet according to claim 1 wherein the core segment has a linear or star structure.

8. A coated sheet according to claim 7 wherein the connected branch copolymer has a divalent linear core segment connecting two polyvalent, non-crosslinked, branched polymer segments, which are in turn connected to two sets of linear polymer segments.

9. A coated sheet according to claim 7 wherein, in the capped connected branch copolymer, the linear core segment comprises an oxyalkylene homopolymer, or a random or block copolymer of an oxyalkylene.

10. A coated sheet according to claim 9 wherein, in the capped connected branch copolymer, the core segment comprises an ethylene oxide/propylene oxide copolymer or an ethylene oxide homopolymer.

11. A coated sheet according to claim 9 wherein, in the capped connected branch copolymer, the core segment has an average molecular weight in the range of about 4000 to about 16000.

12. A coated sheet according to claim 1 wherein, in the capped connected branch copolymer, at least one branched polymer segment comprises a glycidyl polyether.

13. A coated sheet according to claim 12 wherein the glycidyl polyether is derived from glycidol.

14. A coated sheet according to claim 1 wherein, in the capped connected branch copolymer, the linear polymer segments comprise ethylene oxide/propylene oxide copolymer or ethylene oxide homopolymers.

15. A coated sheet according to claim 1 wherein, in the capped connected branch copolymer, the average number of linear polymer segments in the group of linear polymer segments to which the cap segments are attached is from about 8 to about 30.

16. A coated sheet according to claim 1 wherein, in the capped connected branch copolymer, the average molecular weight of each of the group of linear polymer segments to which the cap segments are attached is from about 4000 to about 10000.

17. A coated sheet according to claim 1 wherein, in the capped connected branch copolymer, there are on average from about 0.75 to about 3 of said alkylene oxide residues for each terminal of the terminal linear polymer segments not connected to the branched polymer segments.

18. A coated sheet according to claim 17 wherein, in the capped connected branch copolymer, there on average from about 1 to about 2 of said alkylene oxide residues for each terminal of the terminal linear polymer segments not connected to the branched polymer segments.

19. A coated sheet according to claim 1 wherein, in the capped connected branch copolymer, the alkylene oxide residues comprise residues of an epoxyalkane containing from about 8 about 16 carbon atoms.

20. A coated sheet according to claim 19 wherein, in the capped connected branch copolymer, the alkylene oxide residues comprise residues of a 1,2-epoxy straight-chain alkane containing from about 8 to about 16 carbon atoms.

21. A coated sheet according to claim 2 wherein the capped connected branch copolymer has a molecular weight in the range of about 20,000 to about 80,000.

22. A coated sheet according to claim 1 in combination with a second flat sheet of solid material having at least part of one surface coated with a color developing composition such that the color precursor will, upon contact with the color developing composition, generate a colored mark.

23. A coated sheet according to claim 22 wherein said first and second sheets are releasably secured together so that they lie flat against one another with a surface of the sheet bearing the layer of the color precursor composition being disposed adjacent and facing a surface of the second sheet bearing the color developing composition.

24. A process for preparing a coated sheet for use in a carbonless copying system, the process comprising:

preparing a color precursor composition comprising a capped connected branch copolymer comprising;

(A) a core segment having a valence of v, wherein v is an integer, and having correspondingly v terminal bonds connected to;

(B) v polyvalent, non-crosslinked branched polymer segments each having an average of t terminal bonds, wherein t is greater than about two, one of said terminal bonds being connected to said core segment, and each of said branched polymer segments being connected via its remaining (t-1) terminal bonds to;

(C) a set of linear polymer segments, with an average of t-1 linear polymer segments per set, to provide a group of about v (t-1) linear polymer segments wherein the linear polymer segments have substantially similar chain lengths and composition within said group, the capped connected branch copolymer having a group of terminal linear polymer segments bearing groups capable of effecting hydrogen bonding; and

(D) a set of cap segments connected to terminals of the terminal linear polymer segments which are not connected to the branched polymer segments, each of the cap segments comprising at least one residue of an alkylene oxide containing at least about 4 carbon atoms, there being on average at least about 0.5 of said alkylene oxide residues for each terminal of the terminal linear polymer segments not connected to the branched polymer segments; and

a plurality of microcapsules dispersed in the capped connected branch copolymer, these microcapsules comprising a color precursor;

heating the color precursor composition to a temperature above the transition temperature of the capped connected branch copolymer but insufficient to cause substantial rupturing of the microcapsules, thereby rendering the color precursor composition flowable;

spreading the flowable color precursor composition on to a flat sheet of solid material, the sheet having first and second flat surfaces on opposed sides thereof, the sheet being capable of receiving impressions on at least part of its first surface, and the color precursor composition being spread over at least part of the second surface of the sheet; and

allowing the color precursor composition on the second surface of the sheet to cool below the transition temperature of the capped connected branch copolymer, thereby producing a coherent solid layer of the color precursor composition on the second surface of the sheet.