Radiation curable resin composition and rapid prototyping process using the same

1. A radiation curable composition comprising relative to the total weight of the composition

A 0–25 wt % of a cationically curable component having a linking aliphatic ester group

B 10–85 wt % of an epoxy group containing component other than A

C 1–50 wt % of an oxetane group containing component

D 1–25 wt % of a multifunctional acrylate

E a radical photoinitiator

F a cationic photoinitiator.

2. The radiation curable composition according to claim 1 , wherein component A comprises two cyclohexenoxide groups.

3. The radiation curable composition according to claim 1 , wherein the amount of component A is between 0 and 15 wt %.

4. The radiation curable composition according to claim 1 , wherein component B comprises a glycidyl ether group.

5. The resin composition according to claim 4 , wherein the molar ratio of oxetane to glycidyl ether is between 0.1 and 1.5.

6. The radiation curable composition according to claim 4 , wherein the composition contains a glycidyl ether of hydrogenated bisphenol A.

7. The resin composition according to claim 4 , wherein the weight ratio of glycidyl ethers to epoxy-group containing components that have linking aliphatic ester groups is larger than 1.5

8. The radiation curable composition according to claim 1 , wherein the composition comprises relative to the total weight of the composition 30–75 wt % of component B having a glycidyl ether group, 10–25 wt % of component C and 2–15 wt % of the multifunctional acrylate compound D.

9. The radiation curable component according to claim 1 , wherein the oxetane is choosen from the group consisting of components defined by formula 2,

wherein R 1 is a C1–C4 alkyl group, Z=Oxygen and R 2 =H, a C1–C8 alkyl group or a phenylgroup; 3-ethyl-3-hydroxymethyloxetane, (3-ethyl-3-oxetanylmethoxy)methylbenzene, (3-ethyl-3-oxetanylmethoxy)benzene, 2-ethylhexyl (3-ethyl-3-oxetanyl methyl) ether, 1,4-bis[(3-ethyl-3-oxetanylmethoxy)methyl]benzene, 1,2-bis[(3-ethyl-3-oxetanylmethoxy)methyl]ethane, 1,3-bis[(3-ethyl-3-oxetanylmethoxy)methyl]propane, ethylene glycol bis(3-ethyl-3-oxetanylmethyl) ether and bis(3-ethyl-3-oxetanylmethyl) ether.

10. The radiation curable composition according to claim 1 , wherein the composition after full cure with actinic radiation and 60 min UV postcure has at least one of the following properties

(i) a flexural modulus in the range of 1000 to 100000 MPa;

(ii) an average elongation at break of at least 4%; and

(iii) a tensile strenght of at least 25 MPa.

11. The radiation curable composition according to claim 1 , wherein a photo-fabricated article, obtained by repeating the steps of forming a layer of the composition and selectively irradiating the layer of the composition with actinic radiation, followed by postcure during 60 minutes in a postcure apparatus and subsequent conditioning of the article during 48 hours at a temperature of 20° C. and a relative humidity of 80% RH, has at least one of the following properties

(i) a flexural modulus in the range of 500 to 10000 MPa;

(ii) an average elongation at break of at least 3%; and/or

(iii) a tensile strength of at least 25 MPa.

12. The resin composition according to claim 1 , wherein the amount of components having linking aliphatic ester groups is less than 100 meq of ester links/100 g of composition.

13. The resin composition according to claim 1 , wherein the amount of components having linking aliphatic ester groups is less than 25 meq of ester links/100 g of composition.

14. The composition according to claim 1 , wherein the composition contains a filler.

15. A process for forming a three-dimensional article comprising:

(1) coating a layer of a composition onto a surface, wherein the composition is used as defined in claim 1 ;

(2) exposing the layer imagewise to actinic radiation to form an imaged cross-section, wherein the radiation is of sufficient intensity to cause substantial curing of the layer in the exposed areas;

(3) coating a layer of the composition onto the previously exposed imaged cross-section;

(4) exposing said thin layer from step (3) imagewise to actinic radiation to form an additional imaged cross-section, wherein the radiation is of sufficient intensity to cause substantial curing of the thin layer in the exposed areas and to cause adhesion to the previously exposed imaged cross-section;

(5) repeating steps (3) and (4) a sufficient number of times in order to build up the three-dimensional article.

16. The process of claim 15 , wherein the actinic radiation is in the range of 280–650 nm.

17. The process of claim 15 , wherein the exposure energy is in the range of 10–150 mJ/cm.

18. A stereolithography resin having the composition of claim 1 .

19. The radiation curable composition according to claim 1 , wherein the amount of component A is 0–20 wt. %.

20. A radiation curable composition comprising relative to the total weight of the composition

A a cationically curable component having a linking aliphatic ester group

B 10–85 wt % of an epoxy group containing component other than A

C 1–50 wt % of an oxetane group containing component

D 1–25 wt % of a multifunctional acrylate

E a radical photoinitiator

F a cationic photoinitiator.

wherein the amount of components having linking aliphatic ester groups is less than 100 meq of ester links/100 g of composition.

21. A radiation curable composition comprising relative to the total weight of the composition

A 0–25 wt % of a component having a linking ester group and two cyclohexeneoxide groups

B 10–85 wt % of an epoxy group containing component other than A

C 1–29 wt % of an oxetane group containing component

D 1–25 wt % of a multifunctional acrylate

E 0,1–10 wt % of a radical photoinitiator

F 0,1–10 wt % of a cationic photoinitiator

wherein a photo-fabricated article, obtained by repeating the steps of forming a layer of the composition and selectively irradiating the layer of the composition with actinic radiation, followed by postcure during 60 minutes in a postcure apparatus and subsequent conditioning of the article during 48 hours at a temperature of 20° C. and a relative humidity of 80% RH, has at least one of the following properties

(i) a flexural modulus in the range of 500 to 10000 MPa;

(ii) an average elongation at break of at least 3%; and

(iii) a tensile strength of at least 25 MPa.

22. The radiation curable composition according to claim 21 , wherein the composition comprises 30–75 wt % of component B having a glycidyl ether group, 10–25 wt % of component C and 2–15 wt % of the multifunctional acrylate compound D.