Stabilization of liquid radiation-curable compositions against undesired premature polymerization

• US 5,783,358 A
• Filed: 03/06/1996
• Issued: 07/21/1998
• Est. Priority Date: 03/13/1995
• Status: Expired due to Term

• Current Assignee: 3D Systems, Inc. (3D Systems Corporation)
• Original Assignee: CIBA Specialty Chemicals
• Inventors: Hofmann, Manfred, Schulthess, Adrian, Steinmann, Bettina
• Primary Examiner(s): Berman, Susan W.
• Application Number:
  US08/611,914
• Time in Patent Office: 867 Days
• Field of Search: 522/113, 522/129, 522/120, 522/121, 522/170, 522/182, 522/31, 522/66, 522/90, 522/100, 430/269, 430/280.1
• US Class Current: 430/269
• CPC Class Codes: B33Y 70/00 Materials specially adapted for additive manufacturing
• CPC Class Codes: C08G 59/68 characterised by the catalysts used
• CPC Class Codes: G03F 7/0037 Production of three-dimensional images
• CPC Class Codes: G03F 7/0045 with organic non-macromolecular light-sensitive compounds not otherwise provided for, e.g. dissolution inhibitors
• 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

Abstract

The invention relates to a process for stabilizing a liquid radiation-curable composition comprising a cationically polymerizable compound and a photoinitiator for cationic polymerization against premature commencement of the polymerization, in which a basic ion exchanger is brought into contact with the composition, at least for a certain time. The ion exchanger is preferably removed before commencement of the radiation curing, at least from the part of the radiation-sensitive composition which comes into contact with the radiation. The process is particularly suitable for stabilizing stereolithography baths in extended use against an undesired increase in viscosity.

Claims

1. In a process for the production of three-dimensional articles in a stereolithographic bath which process comprises the step of sequentially irradiating a plurality of layers of a liquid radiation-curable composition comprising a cationically polymerizable compound and a photoinitiator for cationic polymerization, the improvement of stabilizing said composition in said stereolithographic bath against a premature commencement of the polymerization associated with an unintended increase of the viscosity of the composition during the time period of its use comprising bringing a basic ion exchanger material into contact with said composition, for a time sufficient to effect said stabilization.

2. A process according to claim 1, in which the ion exchanger is removed before commencement of the radiation curing, at least from the part of the radiation-sensitive composition which comes into contact with the radiation.

3. A process according to claim 1, in which soluble basic impurities are removed from the ion exchanger material before the ion exchanger is brought into contact with the liquid radiation-curable composition.

4. A process according to claim 1, in which the ion exchanger is in a container which is introduced into the stereolithography bath, at least for a certain time, and which is totally impermeable to the ion exchanger, but is permeable to the curable composition, at least in one area.

5. A process according to claim 4, in which a relative movement takes place between the liquid composition in the stereolithography bath and the container while the container is in the bath.

6. A process according to claim 1, in which the cationically polymerizable compound in the liquid radiation-curable composition is at least one epoxy resin.

7. A process according to claim 6, in which the liquid radiation-curable composition also comprises at least a compound which can be cured by means of free radicals or a mixture of two or more of these compounds, and a photoinitiator for free-radical polymerization.