Water based concentrated product forms of photoinitiators made by a heterophase polymerization technique

1 . A concentrated aqueous polymer dispersion with an average particle size of less than 1000 nm comprising

a) a polymer carrier prepared by heterophase radical polymerization of at least one ethylenically unsaturated monomer in the presence of

b) a photoinitiator and/or photolatent catalyst and

c) optionally a non-ionic, cationic or anionic surfactant,

wherein the weight ratio of the photoinitiator and/or photolatent catalyst to the polymer carrier is greater than 35 parts of photoinitiator and/or photolatent catalyst per 100 parts of polymer carrier.

2 . (canceled)

3 . A concentrated aqueous polymer dispersion according to claim 1 wherein the photoinitiator is selected from alpha-hydroxyketones, bisacylphosphine oxides or phenylglyoxylates.

4 . A concentrated aqueous polymer dispersion according to claim 1 wherein the photoinitiator is a blend selected from alpha hydroxyketones with benzophenones, alpha hydroxyketones with bisacylphosphine oxides, alpha hydroxyketones with benzophenones and with bisacylphosphine oxides as well as blends of mono- and bisacylphosphine oxides.

5 . A concentrated aqueous polymer dispersion according to claim 1 , wherein the ethylenically unsaturated monomers are selected from the group consisting of C 1 -C 18 acrylates, C 1 -C 18 methacrylates, acrylic acid, (meth)acrylic acid, styrene, vinyltoluene, hydroxy-functional acrylates, hydroxy-functional (meth)acrylates, acrylates derived from alkoxylated alcohols, (meth)acrylates derived from alkoxylated alcohols, multifunctional acrylates, and multifunctional (meth)acrylates or mixtures thereof.

6 . A concentrated aqueous polymer dispersion according to claim 1 comprising a mixture of at least two ethylenically unsaturated monomers and at least one crosslinking monomer which is bifunctional and which is selected from divinyl-benzene, ethylene glycol diacrylate, butylene glycol diacrylate or diethylene glycol diacrylate.

7 . A process for the preparation of a concentrated aqueous polymer dispersion with an average particle size of less than 1000 nm comprising the step

polymerizing at least one ethylenically unsaturated monomer in the presence of a photoinitiator and/or a photolatent catalyst by heterophase radical polymerization; wherein the weight ratio of the photoinitiator and/or a photolatent catalyst to the polymer carrier formed from the ethylenically unsaturated monomer is equal or greater than 35 parts of photoinitiator and/or photolatent catalyst per 100 parts of polymer carrier.

8 . A process according to claim 7 comprising the steps of

a) dissolving, emulsifying or dispersing a photoinitiator and/or photolatent catalyst in at least one ethylenically unsaturated monomer;

b) preparing a conventional oil in water emulsion of said photoinitiator and/or photolatent catalyst dissolved, emulsified or dispersed in at least one ethylenically unsaturated monomer;

c) homogenizing the conventional emulsion to a mini-emulsion wherein the droplets of the organic phase have an average diameter below 1000 nm;

d) polymerizing the mini-emulsion by adding a polymerization initiator;

wherein the weight ratio of the photoinitiator and/or a photolatent catalyst to the polymer carrier formed from the ethylenically unsaturated monomer is equal or greater than 35 parts of photoinitiator and/or photolatent catalyst per 100 parts of polymer carrier.

9 . A process for preparing a polymer powder by preparing a concentrated aqueous polymer dispersion according to claim 7 followed by vaporizing the volatile components of the concentrated aqueous polymer dispersion.

10 . A polymer powder obtained by a process according to claim 9 .

11 . Aqueous or non-aqueous formulations, coatings, inks, adhesives or in formulations for electronic materials comprising the aqueous polymer dispersion according to claim 1 .

12 . A process for preparing a polymer powder by preparing a concentrated aqueous polymer dispersion according to claim 8 followed by vaporizing the volatile components of the concentrated aqueous polymer dispersion.

13 . A polymer powder obtained by a process according to claim 12 .

14 . Aqueous or non-aqueous formulations, coatings, inks, adhesives or in formulations for electronic materials comprising the polymer powder according to claim 10 .

15 . Aqueous or non-aqueous formulations, coatings, inks, adhesives or in formulations for electronic materials comprising the polymer powder according to claim 13 .