# US 5,705,116 A · Increasing the useful range of cationic photoinitiators in stereolithography

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- Number: US 5,705,116 A
- Document ID: US5705116A
- Status: Granted
- Kind: A
- Application number: 08/463,086
- Filed: 1995-06-21
- Granted: 1998-01-06
- Earliest claimed: 1994-06-27
- Inventors: Eugene Valentine Sitzmann; Russell Frank Anderson; Darryl Keith Barnes; Ashwin B. Patel
- Web page: https://patentgrep.com/patent/US5705116A

## CPC

- G03F 7/0037: {Production of three-dimensional images}
- B33Y 70/00: Materials specially adapted for additive manufacturing
- G03F 7/029: Inorganic compounds; Onium compounds; Organic compounds having hetero atoms other than oxygen, nitrogen or sulfur
- 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)
- G03F 7/091: {characterised by antireflection means or light filtering or absorbing means, e.g. anti-halation, contrast enhancement}
- B33Y 30/00: Apparatus for additive manufacturing; Details thereof or accessories therefor
- G03F: PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR; (phototypographic composing devices B41B; photosensitive materials or processes for photographic purposes G03C; electrophotography, sensitive layers or processes therefor G03G)
- B33Y: ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING

## 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

### Claim 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: R.sub.1 -R.sub.10 are independently selected from the group consisting of H, alkyl, alkoxy, aryl, carboxyl, and carbinol moieties.

### Claim 2 (depends on 1)

The process of claim 1 where at least two of R.sub.1 -R.sub.10 are alkoxy.

### Claim 3 (depends on 2)

The process of claim 2 wherein R.sub.2 is ethyl and R.sub.9 and R.sub.10 are --OCH.sub.3.

### Claim 4 (depends on 2)

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

### Claim 5 (depends on 1)

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

### Claim 6 (depends on 5)

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

### Claim 7 (depends on 1)

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

### Claim 8 (depends on 7)

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