Photocurable Compositions

• US 20070205528A1
• Filed: 03/21/2005
• Published: 09/06/2007
• Est. Priority Date: 03/22/2004
• Status: Active Grant

• Current Assignee: 3D Systems, Inc. (3D Systems Corporation)
• Original Assignee: Huntsman Advanced Materials Americas, Inc.
• Inventors: Zhao, Yong, Patel, Ranjana, Rhodes, Michael
• Granted Patent: US 8,097,399 B2
• Time in Patent Office: Days
• US Class Current: 264/16
• CPC Class Codes: B29C 2035/0827 using UV radiation
• CPC Class Codes: B29K 2033/00 Use of polymers of unsaturated acids or derivatives thereof as moulding material B29K2035/00 takes precedence
• CPC Class Codes: B33Y 70/00 Materials specially adapted for additive manufacturing
• CPC Class Codes: G03F 7/0037 Production of three-dimensional images
• CPC Class Codes: G03F 7/038 Macromolecular compounds which are rendered insoluble or differentially wettable G03F7/075 takes precedence; macromolecular azides G03F7/012; macromolecular diazonium compounds G03F7/021

Abstract

An optical moulding process is disclosed comprising the sequential steps of: (a)(y) forming a layer of a photocurable composition; and (bXz) irradiating selected areas of the composition in the layer with radiation from a radiation source, thereby curing the composition in said selected areas and repeating the steps a) and b) on top of an earlier cured layer to form a three dimensional structure, wherein the radiation source used in step b) is a non-coherent source of radiation and wherein the photocurable composition comprises at least two curable components: (i) 45%-95% (and preferably at least 50%, more preferably at least 60%, e.g. at least 70%) by weight of the total curable components in the composition is a first component that is photocurable and that is such that, when cured in the presence of a photocuring initiator by exposure to UV radiation having an energy of 30 mJ/cm², at least 90% of the component is cured within 50 milliseconds; and (ii) 5% to 55% (and preferably 10-40%, more preferably 15 to 30%, e.g. about 20%) by weight of the total curable components in the composition is a second component that results in the composition, on curing, shrinking, in a linear direction, by less than 3% and preferably that results in the composition having, after cure, a T_g of greater than 50° C., preferably at least 100° C. and more preferably at least 120° C.

Claims

1. A layerwise optical moulding process for producing a three-dimensional article in sequential cross-sectional layers comprising the steps of:

(a) forming a first layer of a photocurable composition which comprises at least two curable components;

(i) at least 70% by weight of the total curable components in the composition is a first component that is photocurable and that is such that, when cured in the presence of a photocuring initiator by exposure to UV radiation having an energy of 30 mJ/cm², at least 90% by weight of the component is cured within 50 milliseconds; and

(ii) at least 5% by weight of the total curable components in the composition is a second component that results in the composition, on curing, shrinking, in a linear direction, by less than 3% in length.

(b) exposing the first layer to actinic radiation from a non-coherent light source in a pattern corresponding to a respective cross-sectional layer of the three-dimensional article wherein the exposure is sufficient to harden the first layer;

(c) forming a second layer of the photocurable composition above the hardened first layer;

(d) exposing the second layer to layer to actinic radiation from a non-coherent light source in a pattern corresponding to a respective cross-sectional layer of the three-dimensional article wherein the exposure is sufficient to harden the second layer;

(e) repeating steps (c) and (d) as desired to form the three-dimensional article.

2. A process as claimed in claim 1, wherein at least 90% by weight of the first component is cured within 50 milliseconds, when the first component is cured in the presence of a photocuring initiator by exposure to UV radiation having an energy of 20 mJ/cm².

3. A process as claimed in claim 1, wherein the first component comprises one or more materials selected from the group consisting of:

(a) an acrylate

(b) an amine base proliferation system comprising an amine photoinitiator, a base amplifier and an anionically curable material,

(c) an acid amplified system comprising at least one cationically photocurable material, and

(d) a polymer chain, having 2 or more functional photoinitation groups that, on exposure to radiation, can form reactive groups that react with curable components in the composition to incorporate the said polymer chain into the cured composition.

4. A process as claimed in claim 1 wherein the second component comprises one or more material selected from the group consisting of:

(a) a methacrylate or a mixture thereof

(b) a compound having at least one terminal —

SH, —

NH or —

OH group, and

(c) an isocyanate, optionally blended with a latent polyol

(d) an epoxy optionally with an acid amplifier,

(e) an oxetane,

(f) a furan, and

(g) an ortho spiro compound.

5. A process as claimed in claim 4, wherein the second component comprises a polythiol having two or more thiol groups per molecule.

6. A process as claimed in claim 1 wherein the photocurable composition also contains one or more flexibiliser or toughener.

7. An optical moulding composition comprising, in weight percent:

(a) at least two curable components;

(i) a first component in an amount of at least 80%, based on the total weight of the curable components in the composition, the first component being photocurable and such that, when cured in the presence of a photocuring initiator by exposure to UV radiation having an energy of 30 mJ/cm², at least 90% by weight of the component is cured within 100 milliseconds; and

(ii) a curable second component in an amount of at least 5% by weight of the total curable components in the composition, the second component being a compound having at least one terminal thiol group,

(b) 1 to 10%, by weight, of a cationic photoinitiator,

(c) 0.01 to 10%, by weight, of a radical photoinitiator,

(d) 0 to 5% by weight of a stabilizer against premature curing prior to use in the process, and

(e) 0 to 20% by weight of auxiliary materials.

8. A composition as claimed in claim 7, wherein at least 90% by weight of the first component is cured within 50 milliseconds, when the first component is cured in the presence of a photocuring initiator by exposure to UV radiation having an energy of 20 mJ/cm².

9. A composition as claimed in claim 7, wherein the first component comprises one or more materials selected from the group consisting of:

(a) an acrylate,

(b) an amine base proliferation system comprising an amine photoinitiator and a photo-polybase amplificater, and an anionically photocurable material, and

(c) an acid amplified system comprising at least one cationically photocurable material, a cationic photocuring initiator, and an acid amplifier.

10. A composition as claimed in claim 7, wherein the photocurable composition also contains

1 to 10% by weight of one or more flexibilisers or tougheners.

11. A composition as claimed in claim 7, wherein the first component is an acrylate.

12. A composition as claimed in claim 7, wherein the first component includes a carbon-carbon double bond and the ratio of double bonds to thiol groups in the composition is 10:

1 to 2;

1.