Method of forming a three-dimensional object comprising additives imparting reduction of shrinkage to photohardenable compositions

Claim 1

A method for accurately fabricating an integral three dimensional object from successive layers of a photohardenable liquid composition comprising the steps of: (a) forming a layer of a liquid photohardenable liquid; (b) photohardening at least a portion of the layer of photohardenable liquid by exposure to actinic radiation; (c) introducing a new layer of photohardenable liquid onto the layer previously exposed to actinic radiation; and (d) photohardening at least a portion of the new liquid layer by exposure to actinic radiation, with the requirement that the photohardenable composition comprises an ethylenically unsaturated monomer, a photoinitiator, and a linear polymer mixed therein selected from the group consisting of polystyrene, substituted polystyrene, alpha alkyl polystyrene, beta alkyl polystyrene, substituted alpha alkyl polystyrene, substituted beta alkyl polystyrene, and mixture thereof, the linear polymer being soluble in the composition but separating into a separate phase upon photohardening the composition, the linear polymer occupying a first volume in the absence of all other components of the composition, the photohardenable composition occupying a second volume in the absence of the linear polymer mixed therein, and the photohardenable composition containing the linear polymer occupying a third volume, wherein the third volume is smaller than the sum of the first volume and the second volume.

Claim 2

A method for accurately fabricating an integral three dimensional object from successive layers of a photohardenable liquid composition comprising the steps of: (a) forming a layer of a liquid photohardenable liquid; (b) photohardening at least a portion of the layer of photohardenable liquid by exposure to actinic radiation; (c) introducing a new layer of photohardenable liquid onto the layer previously exposed to actinic radiation; and (d) photohardening at least a portion of the new liquid layer by exposure to actinic radiation, with the requirement that the photohardenable composition comprises an ethylenically unsaturated monomer, a photoinitiator, and a linear polymer mixed therein selected from the group consisting of polystyrene, substituted polystyrene, alpha alkyl polystyrene, beta alkyl polystyrene, substituted alpha alkyl polystyrene, substituted beta alkyl polystyrene, and mixture thereof, the linear polymer being soluble in the composition but separating into a separate phase upon photohardening the composition, the linear polymer occupying a first volume in the absence of all other components of the composition, the photohardenable composition occupying a second volume in the absence of the linear polymer mixed therein, and the photohardenable composition containing the linear polymer occupying a third volume, wherein the third volume is smaller than the sum of the first volume and the second volume.