Photocurable composition for producing cured articles having high clarity and improved mechanical properties

1. A photocurable composition comprising:

(a) an epoxy component containing one or more epoxy compounds with from 0 to no more than 5% of the epoxy component being a glycidyl epoxy compound;

(b) a (meth)acrylate component containing one or more multifunctional (meth)acrylates comprising trimethylolpropane ethoxylated triacrylate and wherein the one or more methacrylates contain no hydroxyl groups and;

(c) a component comprising propoxylated glycerine;

(d) a cationic photoinitiator; and

(e) a free radical photoinitiator wherein the composition contains at least about 4% by weight and at most 20% by weight of component (b) and about 0.01% to about 10% by weight of component (c) and wherein the composition after cure has a yellow index/inch value of less than 80 .

2. The photocurable composition of claim 1 wherein the one or more multifunctional (meth)acrylates comprise a pentaerythritol (meth)acrylate.

3. The photocurable composition of claim 2 wherein the pentaerythritol (meth)acrylate comprises pentaerythritol triacrylate and/or pentaerythritol tetraacrylate.

4. The photocurable composition of claim 1 wherein the one or more multifunctional (meth)acrylates comprise a dipentaerythritol (meth)acrylate.

5. The photocurable composition of claim 4 wherein the dipentaerythritol (meth)acrylate is dipentaerythritol hexaacrylate.

6. The photocurable composition of claim 1 wherein component (c) has a molecular weight of 1500 or less.

7. A process for producing a three-dimensional article in sequential cross-sectional layers in accordance with a model of the article, the process comprising the steps of:

(1) forming a first layer of the photocurable composition of claim 1 ;

(2) exposing the first layer to actinic radiation in a pattern corresponding to a respective cross-sectional layer of the model sufficient to harden the first layer in the imaged area;

(3) forming a second layer of the photocurable composition of claim 1 above the hardened first layer;

(4) exposing the second layer to actinic radiation in a pattern corresponding to a respective cross-sectional layer of the model sufficient to harden the second layer in the imaged area; and

(5) repeating steps (3)-(4) to form successive layers to form the three-dimensional article.

8. A process for forming a three-dimensional article in sequential cross-sectional layers in accordance with a model of the article, the process comprising the steps of: depositing droplets of the photocurable composition of claim 1 onto a substrate in a pattern corresponding to a cross-sectional layer of the model so that adjacent droplets merge together; repeating this step to form successive layers; and applying actinic radiation to cure the photocurable composition of claim 1 , pixel-by-pixel, line-by-line, layer-by-layer, after several layers have been formed and/or after all the layers have been formed to form the three-dimensional article.

9. A three-dimensional article produced according to the process of claim 7 .

10. A three-dimensional article produced according to the process of claim 8 .

11. A photocurable composition comprising:

(a) a cationically curable component formed from one or more epoxy compounds with from 0 to no more than 5% of the curable component being a glycidyl epoxy compound;

(b) a (meth)acrylate component comprising trimethylolpropane ethoxylated triacrylate and wherein the methacrylate component contains no hydroxyl groups;

(c) a polyol component comprising propoxylated glycerine;

(d) a cationic photoinitiator; and

(e) a free radical photoinitiator

wherein the composition contains at least about 4% by weight and at most 20% by weight of component (b) and about 0.01% to about 10% by weight of component (c) and wherein the composition after cure has a yellow index/inch value of less than 80.

12. The photocurable composition of claim 1 wherein the (meth)acrylate component comprises dipentaerythritol hexaacrylate.

13. A photocurable composition comprising:

(a) a cationically curable component formed from one or more epoxy compounds with from 0 to no more than 5% of the curable component being a glycidyl epoxy compound;

(b) a (meth)acrylate component comprising trimethylolpropane ethoxylated triacrylate and wherein the methacrylate component contains no hydroxyl groups;

(c) a polyol component comprising propoxylated glycerine;

(d) a cationic photoinitiator; and

(e) a free radical photoinitiator

wherein the composition contains at least about 4% by weight and at most 20% by weight of component (b) and about 0.01% by to about 10% by weight of component (c) and wherein the composition after cure has a yellow index/inch value of less than 80.