Catherine Y Chang

US Patent:

RE287890, Apr 27, 1976

Filed:

Aug 28, 1975

Appl. No.:

5/608673

Inventors:

Catherine Teh-Lin Chang - Wilmington DE

Assignee:

E. I. Du Pont de Nemours and Company - Wilmington DE

International Classification:

G03C 194
G03C 168
C08F 246

US Classification:

96 86P

Abstract:

Photopolymerizable compositions comprising an ethylenically unsaturated monomer and an initiating combination of a cyclic cis-. alpha. -dicarbonyl compound and certain radiation-absorbing sensitizers are disclosed. Compositions of the invention have improved photospeed and may be chosen to provide a wide range of spectral sensitivity.

US Patent:

50432370, Aug 27, 1991

Filed:

Jan 12, 1990

Appl. No.:

7/464058

Inventors:

Catherine Teh-Lin Chang - Wilmington DE

Assignee:

E. I. du Pont de Nemours and Company - Wilmington DE

International Classification:

G03G 1326

US Classification:

430 49

Abstract:

Photohardenable electrostatic master with improved environmental latitude and dot shape comprising (1) an electrically conductive substrate, and coated thereon (2) a layer of photohardenable composition having a speed that requires an exposure energy in the range of 3 to 90 mjoules/sq. cm. consisting essentially of (a) at least two incompatible organic polymeric binders, (b) at least one monomeric compound having at least ethylenically unsaturated group, and (c) a photoinitiator or photoinitiator system that activates polymerization of the ethylenically unsaturated monomer upon exposure to actinic radiation, (d) a chain transfer agent, and (e) at least one polymerization inhibitor in an amount of at least 0. 1% by weight based on the total weight of photohardenable composition. A xeroprinting process is described using the master.

US Patent:

49139983, Apr 3, 1990

Filed:

Dec 30, 1988

Appl. No.:

7/267407

Inventors:

Allan Cairncross - Hockessin DE
Catherine T. Chang - Wilmington DE

Assignee:

E. I. Du Pont de Nemours and Company - Wilmington DE

International Classification:

G03G 5026
G03C 130
G03C 194

US Classification:

430 96

Abstract:

Compositions and films are provided for the preparation of electrostatic printing masters. The composition binder permits use of aqueous silver halide photographic techniques to image the master for printing, and exhibits insulation properties needed for electrostatic printing under typical conditions of relative humidity.

US Patent:

51457601, Sep 8, 1992

Filed:

Oct 26, 1990

Appl. No.:

7/603939

Inventors:

Catherine T. Chang - Wilmington DE
Richard J. Kempf - Towanda PA

Assignee:

E. I. Du Pont de Nemours and Company - Wilmington DE

International Classification:

G03F 506

US Classification:

430 73

Abstract:

High resolution, photosensitive electrostatic master which is positive-working with a single imagewise exposure comprising a conductive support bearing a layer of a photosensitive composition consisting essentially of (a) at least two polymeric binders, at least one binder having a Tg greater than 80. degree. C. and at least one binder having a Tg of 70. degree. C. or less such that the shift in transit time (a. sub. T) of the photosensitive layer in the range of 30%. ltoreq. relative humidity. ltoreq. 60% and 65. degree. F. (18. 3. degree. C. ). ltoreq. temperature. ltoreq. 80. degree. F. (26. 7. degree. C. ) is 10 or less, (b) a hexaarylbiimidazole photooxidant, (c) leuco dye, preferably stabilized, oxidized by (b), (d) a nonionic halogenated compound, preferably a hydrocarbon, and (e) at least one compatible plasticizer. A process of making positive images by a single imagewise exposure is described. The master is useful in making proofs that duplicate the image achieved by printing, and manufacture of printed circuit boards, etc.

US Patent:

51206293, Jun 9, 1992

Filed:

Apr 10, 1990

Appl. No.:

7/507338

Inventors:

Richard D. Bauer - Kennett Square PA
Catherine T. Chang - Wilmington DE

Assignee:

E. I. du Pont de Nemours and Company - Wilmington DE

International Classification:

G03G 500

US Classification:

430 70

Abstract:

High resolution photosensitive electrostatic master which forms conductive exposed image areas upon imagewise exposure comprising an electrically conductive substrate bearing a photosensitive layer consisting essentially of at least one acid labile compound which decomposes to form acid, and a photoinitiator or photoinitiating system which upon exposure generates a catalytic amount of a strong acid. A xeroprinting process from producing positive images in said photosensitive layer of the master is also disclosed. The master is useful in the graphic arts field. e. g. , making color proofs, preparation of printing circuit boards, resists, solder masks, etc.

US Patent:

50285033, Jul 2, 1991

Filed:

Sep 21, 1989

Appl. No.:

7/410655

Inventors:

Catherine T. Chang - Wilmington DE

Assignee:

E. I. Du Pont de Nemours and Company - Wilmington DE

International Classification:

G03C 1725
G03C 173
G03G 1500

US Classification:

430281

Abstract:

Photohardenable electrostatic master with improved backtransfer characteristics comprising (1) an electrically conductive substrate, and (2) a layer of photohardenable composition consisting essentially of (a) at least one organic polymeric binder, (b) at least one compound having at least one ethylenically unsaturated group, and (c) a photoinitiator or photoinitiator system, and (d) an acidic additive as defined. A xeroprinting process is described using the master. The master is used in graphic arts, color proofing which duplicates images produced by printing, preparation of printed circuit boards, resists, soldermasks, etc.

US Patent:

50647407, Nov 12, 1991

Filed:

Dec 3, 1990

Appl. No.:

7/620895

Inventors:

Catherine T. Chang - Wilmington DE
Curtis R. Fincher - Wilmington DE

Assignee:

E. I. Du Pont de Nemours and Company - Wilmington DE

International Classification:

G03G 1314
G03G 1328

US Classification:

430126

Abstract:

Xeroprinting process comprising (A) exposing imagewise to actinic radiation a photohardenable electrostatic master comprising (1) an electrically conductive substrate, and (2) a layer of photohardenable composition consisting essentially of (a) at least two organic polymeric binders, at least one having a Tg greater than 80. degree. C. and at least one having a Tg less than 70. degree. C. , (b) at least one monomeric compound having at least one ethylenically unsaturated group, and (c) a photoinitiator or photoinitiator system, the shift in transit time (a. sub. T) of the photohardenable layer in the range of 30%. ltoreq. relative humidity. ltoreq. 60% and 15. 6. degree. C. ltoreq. temperature. ltoreq. 26. 7. degree. C.

US Patent:

50064347, Apr 9, 1991

Filed:

May 12, 1989

Appl. No.:

7/351361

Inventors:

Catherine T. Chang - Wilmington DE
Curtis R. Fincher - Wilmington DE

Assignee:

E. I. Du Pont de Nemours and Company - Wilmington DE

International Classification:

G03G 1328
G03C 1725
G03C 173
G03C 1735

US Classification:

430 49

Abstract:

Photohardenable electrostatic master with improved environmental latitude comprising (1) an electrically conductive substrate, and (2) a layer of photohardenable composition consisting essentially of (a) at least two organic polymeric binder, at least one having a Tg greater than 80. degree. C. and at least one having a Tg less than 70. degree. C. , (b) at least one monomeric compound having at least one ethylenically unsaturated group, and (c) a photoinitiator or photoinitiator system, the shift in transit time (a. sub. T) of the photohardenable layer in the range of 30%. ltoreq. relative humidity. ltoreq. 60% and 15. 6. degree. C. ltoreq. temperature. ltoreq. 26. 7. degree. C. is 15 or less, preferably 10 or less. A xeroprinting process is described using the master.