Increasing the useful range of cationic photoinitiators in stereolithography

• US 5,705,116 A
• Filed: 06/21/1995
• Issued: 01/06/1998
• Est. Priority Date: 06/27/1994
• Status: Expired due to Term

• Current Assignee: 3D Systems, Inc. (3D Systems Corporation)
• Original Assignee: CIBA Specialty Chemicals
• Inventors: Sitzmann, Eugene Valentine, Anderson, Russell Frank, Barnes, Darryl Keith, Patel, Ashwin B.
• Primary Examiner(s): Tentoni, Leo B.
• Application Number:
  US08/463,086
• Time in Patent Office: 930 Days
• Field of Search: 264/236, 264/308, 264/401, 156/272.8, 156/273.3, 156/273.5, 156/275.5, 156/307.1, 427/508, 427/510, 427/512, 427/553, 427/554, 427/555
• US Class Current: 264/401
• CPC Class Codes: B33Y 30/00 Apparatus for additive manufacturing; Details thereof or accessories therefor
• 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 7/029 Inorganic compounds; Onium compounds; Organic compounds having hetero atoms other than oxygen, nitrogen or sulfur
• 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
• CPC Class Codes: G03F 7/091 characterised by antireflection means or light filtering or absorbing means, e.g. anti-halation, contrast enhancement

Abstract

Polymer precursor formulations suitable for stereolithography may be prepared from compositions containing vinyl ether functionalized compounds and epoxy functionalized compounds plus an effective mount of a cationic photoinitiator and an ultraviolet light-absorbing compound to provide a predetermined depth of cure. Preferably, the ultraviolet light-absorbing compound is anthracene or its derivatives. Anthracenes having pendant alkoxy groups are preferred for use with light wavelengths greater than 360 nm, particularly 9,10-dimethoxy-2-ethyl anthracene.

Claims

1. In the process of stereolithography in which a three-dimensional object is built up in successive layers by polymerizing cationically polymerizable monomers by the catalytic action of cationic photoinitiators activated by a moving beam of ultraviolet light, the improvement comprising adding as an ultraviolet light absorbing compound in quantities sufficient to provide a predetermined depth of cure and having the formula ##STR16## where:

R₁ -R₁₀ are independently selected from the group consisting of H, alkyl, alkoxy, aryl, carboxyl, and carbinol moieties.

2. The process of claim 1 where at least two of R₁ -R₁₀ are alkoxy.

3. The process of claim 2 wherein R₂ is ethyl and R₉ and R₁₀ are --OCH₃.

4. The process of claim 2 wherein said light absorbing compound is up to 0.5 pph relative to said monomers.

5. The process of claim 1 wherein said monomers are a mixture of epoxides and vinyl ethers.

6. The process of claim 5 wherein said mixture has a vinyl ether equivalent weight of 80 to 800.

7. The process of claim 1 wherein said stereolithography employs an argon ion laser.

8. The process of claim 7 wherein said argon ion laser emits ultraviolet energy primarily at 364 nm.