Method for producing microcapsules and photosensitive microcapsules produced thereby

Claim 2

A process for forming microcapsules having discrete capsule walls comprising the steps of forming an emulsion of an oily core material in a continuous aqueous phase containing methylated polygalacturonic acid as an emulsion stabilizer, and enwrapping particles of said oily core material in a formaldehyde condensation product produced by in situ condensation of an amine and formaldehyde.

Claim 3

The process of claim 1 wherein said amine is urea or melamine.

Claim 4

The process of claim 2 wherein said polygalacturonic acid is pectin.

Claim 5

The process of claim 3 wherein said continuous phase additionally includes an anionic colloid.

Claim 6

The process of claim 4 wherein said formaldehyde condensation product is a melamine-formaldehyde resin.

Claim 7

The process of claim 4 wherein said formaldehyde condensation product is a urea-formaldehyde resin.

Claim 8

The process of claim 4 wherein said anionic colloid is isbutylene-maleic anhydride copolymer.

Claim 9

An imaging sheet comprising a support carrying on one surface thereof a layer of microcapsules having discrete capsule walls, said microcapsules containing a radiation sensitive material in the internal phase and being formed by enwrapping particles of an oil-in-water emulsion containing methylated polygalacturonic acid as an emulsion stabilizer in a formaldehyde condensation product produced by in situ polymerization of formaldehyde and an amine, and said capsules being further characterized by an average particle size of about 4 to 8 microns and not less than 90% of said capsules having a particle size less than 10 microns.

Claim 10

An imaging sheet comprising a support carrying on one surface thereof a layer of microcapsules having discrete capsule walls, said microcapsules containing a radiation sensitive material in the internal phase and being formed by enwrapping particles of an oil-in-water emulsion containing methylated polygalacturonic acid as an emulsion stabilizer in a formaldehyde condensation product produced by in situ polymerization of formaldehyde and an amine, and said capsules being further characterized by an average particle size of about 4 to 8 microns and not less than 90% of said capsules having a particle size less than 10 microns.

Claim 11

The imaging sheet of claim 8 wherein said sheet comprises a layer containing a color developer material.

Claim 12

The imaging sheet of claim 8 wherein said condensation product is a urea-formaldehyde resin.

Claim 13

The imaging sheet of claim 8 wherein said condensation product is a melamine-formaldehyde resin.

Claim 14

The imaging sheet of claim 8 wherein said radiation sensitive material includes a polyethylenically unsaturated compound and a photoinitiator.

Claim 15

The imaging sheet of claim 8 wherein said polygalacturonic acid is pectin.

Claim 16

The process of claim 1 wherein said process is further characterized in that the average particle size of said microcapsules is about 4 to 8 microns and at least 90% of said microcapsules are less than or equal to 10 microns.

Claim 17

The process of claim 14 wherein said oily core material comprises a radiation sensitive composition.

Claim 18

The process of claim 1 wherein said methylated polygalacturonic acid has a methylation degree of about 50 to 75%.

Claim 19

The process of claim 16 wherein said continuous phase contains approximately 1.0 to 8% by weight pectin.

Claim 20

The imaging sheet of claim 8 wherein said continuous phase additionally includes an anionic colloid.

Claim 21

The imaging sheet of claim 18 wherein said anionic colloid is isobutylene maleic anhydride copolymer.

Claim 22

The imaging sheet of claim 8 wherein said methylated polygalacturonic acid is characterized by a methylation degree of about 50 to 75% and said methylated polygalacturonic acid is present in said continuous phase in an amount of approximately 1.0 to 8%.

Claim 23

The process of claim 1 wherein said oily core material is enwrapped in a wall-forming material which consist essentially of said formaldehyde condensation product.

Claim 24

The imaging sheet of claim 8 wherein said oily core material is enwrapped in a wall-forming material which consist essentially of said formaldehyde condensation procuct.