CA2054276A1 - Solid imaging semi-permeable film coating - Google Patents

Abstract

TITLE
SOLID IMAGING SEMI-PERMEABLE FILM COATING
ABSTRACT

An apparatus and method for fabricating integral three-dimensional objects from successive layers of photoformable compositions by exposing the layers of the composition through a semi-permeable film that allows creation of release coatings on the side of said film facing said composition.

Description

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~itle SOLID IMAGING SEMI-PERMEABLE FILM COATING

This invention relates to production of three-dimensional ob~ects by photoformlng, ~nd more particularly to the controlled application of thin flat liquid layers accurately and quickly to a ~latform or previously photoformed layer(s) to accomplish salid production with layers of improved flatness, accuracy and ~ntegrity.

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Many systems for production of three-dimensional modeling by photohardening have been proposed. European patent application 250,121 filed by Scitex Corporation, (r~ " ~f ~J.
20 Ltd. on June 6, 1987, discloses a three-dimensional ~ 9/~'6 modeling apparatus using a solidifiable liquid, and provides a good summary of documents pertlnent to this art.

These approaches relate to the formation of solid sectors of three-dimensional ob~ects ln steps by sequential irradiation of areas or volumes sought to be solidi~ied.
Various masking techniques are described as well as the use of direct laser writing, i.e., exposing a photohardenable composit$on with a laser beam according to a desired pattern and building a three-dimensional model layer by layer. In addition to various exposure technlques~ several methods of forming thin liquid layers are described which allow either the coating of a platform initially or the successive coating of object layers previously exposed.

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V. S. Patent 4,575,330 (C. W. Hull), issued ~n ~ ,?
March 11, 1986 and later reexamined ~certificate issued on December 19,1989), describes a system for generating three-dimenslonal objects by creating a cross-sectional pattern of the object to be formed at a selected surface of a fluid medium capable of altering its physical state in respon~e to nppropriate synergistic stimulation by impinging rad~ati~n, particle bombardmenk or c~lemical reaction, : wherein successive adjacent laminae, representing corresponding successi~e ad~acent cross-sections of ~he object, are automatically ~ormed and integrated together to provide a step-wise laminar buildup of the desired object, whereby a three-dimensional object i~ formed ~nd drawn ~rom a substantially planar surface of the fluid medium during the forming process. This patent also describes an embodiment in which a Uv curable liquid floats on a heavier UV transparent liquid which is non-miscible and non-wetting with the curable liquid. In addition, this patent suggests the use of "~ater (or other) release coating" used in conjunction with a CRT and a fiber optic faceplate.
Subsequent patent applications, made by Hull and his associates, published by the European Patent Of~ice and listed in publication number 0 361 847 describe means of providing the thin layers of fluid more quickly using a doctor blade and of controlling the level in a vat of ~luid.

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U. S. Patents 4,752,498 and 4,801,477 (E. V. ~udim) ~ g`t~
issued on June 21, 1988 and January 31, 1989 respectively, describe methods of forming three-dimensional ob~ects, in which a sufficiently rigid transparent plate or film is placed in contact with a liquid photopolymer so as to hold the photopolymer surface to a desired shape, and preferably exclude air, durlng radiation curing through the 35 transparent plate or film. lt is further ~uggested that the ~ ~ '3 surface of the transparent plate or film be made of a material which leaves the irradiated photopolymer surface capable of further crosslinking so that when a subsequent layer is formed it will adhere thereto. Fudim also suggests that this material be made of or contain in it's molecules oxygen, copper or other inhibitors to aid in the release of the layer without distorting the solidified photopolymer.

Publication "Automatic Method ~or Fabricating a Three-Dimensional Plastic Model with Photohardening Polymer" by ~ideo Kodama, Rev. Sci. Instrum. 52~11), 1770-1773, Nov.
1981, describes a method ~or ~utomatic fabrication of a three-dimensional plastic model. The solid model is fabricated by exposing liyuid photo-forming polymer, of 2 mm thickness or less, to ultraviolet rays, and stacking the cross-sectional solidified layers. Publication "Solid Object Generation" by Alan J. Herbert, Journal of Applied Photographic Engineering, 8~4), 185-lB8, August 1982, describes an appara~us which can produce a replica of a solid or three-dimensional object much as a photocopier is capable o~ performing the same task for a two-dimensional object. The apparatus is capable of generating, in photopolymer, simple three-dimensional objects from information stored in computer memory. A good review of the different methods i also given by a more recent publication, titled "A Review of 3D Solid Ob~ect Generation" by A. J. Herbert, Journal of Imaging Technology 15: 186-190 (1989).

Most of these approaches relate to the formation of solid sectors of three-dimensional objects in steps by sequential irradiation of areas or vDlumes sou~ht to be solidified. Variou~ maskin~ techniques are described as well as the use of direct laser writing, ~.e. exposing a photoformable composition with a laser be~m according to a 2 ~ 3 desired pattern and building a three-dimensional model layer by layer. In addition to various exposure techniques, several methods of ~orming thin liquid layers are described which allow both coating a platform initially and coating successive layers pre~iously exposed and solidified.

Current methods of coating suggested thus far, however, have drawbacks in that they are not capable of ensuring flat uniform layer thickness or of producing such layers quickly, or they do not effectlvely prevent damage to previously ~ormed layers during the successive coating process. Furthermore, they omit to rl~cognize very important parameters involved in the coating process such as, for example, the effects of having both solid and liquid regions present during the formation of the thin liquid layers, the effects of fluid flow and rheological characteristics of the liquid, the tendency for thin photoformed layers to easily become distorted by fluid flow during coating, and the effects of weak forces such as, for example, hydrogen bonds and substantially stronger forces such as, for example, mechanical bonds and vacuum or pressure differential ~orces on those thin layers and on the object being formed.

The Hull pa~ent, for example describes a dipping proces~ where a platform is lowered either one layer thickness or is dipped below the distance of one layer ~n a vat then brought up to within one layer thickness of the surface of the photohardenable liquid. Hull further suggests that low viscosity liqulds re pre~er~ble, but for other practical reasons, the photohardenable liquids are generally high viscosity liquids. Although theoretically most liquids will flatten out due to surface tension effects, high viscosity liquids and even low v~scosity liquids take an inordinate amount of t~me to flatten to an ~ i3 acceptable degree especially if large flat areas are being imaged and if the liquid layer thickness is very thin.
Re~ions where previous layers consist of solid walls surrounding liquid pools further compounds the flattening process of the thin liquid layer coating. In addition, motion of the platform and parts, which have cantilevered or beam (regions unsupported in the Z direction by previous layer sections), within the liquid creates deflections in the layers contributing to a lack of tolerance in the finished object. In the embodiment where a heavier transparent liquid is utilized to create the thin flat layers of photopolymer that ~loat on the transparent liquid, there is significan~ rellance on surface tension effects to ensure that the photopolymer layer will be flat.
Reliance on these surface tension effects and the difference in specific gravlties between the two liquids in order to create the flat photopolymer layers is severely complicated by other surface tension effects, such as, for example, meniscus development at the corners of the hardened photopolymer, and ob~ect geometrles that create enclosed areas which produce substantial suction cup type li~ting of the heavier liquid during coating of subsequent layers. In the embodiment where "water (or other) release coating" is proposed for use in conjunction with a CRT and a fiber optic faceplate, the patent does not teach methods by which a release coating could be applied and maintalned on the faceplate surface.

The Muntz patent (U. S. 2,775,758 issued in 1956) and Scitex application describe methods by which the photohardenable liquid is introduced into the vat by means of a pump or similar apparatus such that the new liquid level surface forms in one layer thickness over the previously exposed layers. Such methods have all the 3 ~ ?, rl t problems of the Hull methods except that the deflections of the layers during coating is reduced.

The Fudim patent describes the use of a transmitting material, usually rigid and coated with a film or inherently unlikely to adhere to the hardened photopolymer, to fix the surface of the photopolymer liquid to a desired shape, assumably flat, through which photopolymers of desired thlckness are solidified. The methods described by Fudim do not address the problems inherent in separatlng such a transmissive material from a photopolymer formed in lntimate contact with the sur~ace of the transmissive material. Whereas the effects of chemical bonding may be reduced significantly by ~uitable coatlngs of inherently suitable films, the mechanical bonds along with hydrogen bonds, vacuum forces, and the like are still present and in some cases substantial enough to cause damage to the photopolymer during removal from the transmissive material surface. Furthermore, evaluations made by the Applicants indicate that the forces, resisting ~he separation or even sliding off the photohardenable material exposed in intimate contac~ with the suitably non~adhesive transmissive material, are capable of damaging the photoformed layer especially when suxrounded by photohardenable li~uid and even more especially when the photoformed layers are thin. No method i~ described in the Fudim patent to eliminate these problems.

In the Kodama ~okai Patent No. SHO 56(1981)-144478, Japan, later published on Nov2mber 10, 1981) publication, mention is made of a Teflon, or polyethylçne coated quartz plate, which coating acts ~s a releasing agent allowing the solidified resin to be easily removed from the base ~quartz plate) and preferentially sdhering to the constructing y~

stand (aluminum sheet). This method would have all the difficulties mentioned in the ~udim reference above.

While it may be said that others such as Munz, Kodama, Cubital, Hull, etc. implicitly had air as the atmosphere at the interface of the photopolymer surface, air was not an element comprised within their speci~ications. And the presence, advantages, and uses of air in regions deeper into the compositions talso implicit in previous specificatlons) has not been specified though they are lmpllcit.

In a thesis paper, published by the Departmen~ of Mechanical Engineering, University of Delaware, library catalogue date August 19, 1990, there is mention of an unsuccessful effort, in whlch the author, Hirsch, studied the possibility of creating a porous fused silica plate through which the photopolymer could be exposed. The purpose of the porosity in the plate was to allow air to flow into the surface between the plate and the hardened layer to allow vacuum breaking when they were separated. It was also proposed that the air or oxygen passing through the plate might inhibit the polymeri~ation at this surface aiding in release. This e~fort was unsuccessful primarily due to difficul~ies in obtaining a UV transparent porous plate material. But it also ne~lects concerns such as, for example, polymer adhesion to the fused silica in non-pore regions and eventual bridging of this polymer in subsçquent coating applications which would close o~f the pores, the requirement for very small ~ore sizes which would severely restrict the air flow which is supposed to relieve the vacuum forces, and the lack of any driving forces or pressures to prevent the photopolymer from enterlng the pores or to push the air into the interface between the porous plate and the photopolymer sur~ace.

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One of the objects of the present invention ls therefore to provide a method and spparatus for quickly producing layers of a liquid photoformable material, of preferably .030" thickness or less, which are flat to within preferably .001" per square inch or better, and by which previously exposed layers are minimally distorted or damaged during the coating process for the production of three-dimensional ob~ects by se~uential coating of sald layers and exposure after each coa~ing.

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This invention provides unique solutions to these problems by utilizing a semi-permeable film, which is impermeable to the photoformable composition but is permeable to a deformable-coat~ng-mixture that is non-wetting and immiscible with the photoformable composition.
The deformable-coating-mixture passes through the membrane preferably by diffusion effects and forms a thin, slippery surface on the photoformable composition side of the membrane, thereby eliminating any adhesion ~orces caused by chemical, mechanical or hydrogen bonds and the llke. Also this invention teaches of methods by which dissolved inhibitors can be used within the deformable-coating-mixtures and within the composition to provide improved interlayer adhesion and gentler coating. Furthermore, this invention teaches of methods by which recesss or large orifices can be created, between the film ~nd previously formed layers, through which the photoformable composition may be caused to flow, thereby substantially alleviating vacuum forces ~hat may ar~s~ during separation of the ~ilm from the photoformed layer.

2 ~ ~3 fi ,~ Y~ ij A method for fabricating an lntegral three-dimensional object from successive layers of a photoformable composition comprisin~ the steps of:

a) positioning a substantially transparent, composition-impermeable, composition-inert, semi-permeable film, having a first surface and a second surface, such that said film first surface is, at least partially, in ~ontact with an imaging a~mosphere, and said film second surface is, at least partially, in contact with the pAotoformable composition;

b) contacting an interface of said composition wlth a composition atmosphere;
c) allowing said imaging atmosphere to permeate through said film and partially into a photoformable composition-layer;
0 d) exposing said photoformable-composition-layer to radiation imagewise through said film making a photoformed layer and a deformable-composition~
release-coating;
5 e) sliding said film from said photoformed layer;

f) posi~ioning said film in such a way as to form a photoformable-composition-layer between said previously made photoformed layer and said film second surface; and g) repeating steps c-f until said layers of the integral three-dimensional object are formed.

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Single la~ers may be fabricated as above by performing the steps a-e above.

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The reader's understandlng of practical implementation of preferred embodiments of the invention will be enhanced by reference to the following detailed description taken in con~unction with perusal of the drawing fi~ures, wherein:
Figure 1 depicts the ma~or elements in an embodlment of the invention dur~ng the imaglng step.

Figure 2 depicts a pxeferred embodiment of the lnvention during the process of sliding the lmaged layers in preparation for another photoformable-composition-layer.

Figure 3 depicts an embodiment utilizin~ a porous plate with a partially adhered semi-permeable film in the process of separating the film and coating Prom the photoformed layer.

escri~tion of ~f4~g~r ~ 4U~

This in~ent~on relates to a process and apparatus for producing three-dimensional objects by photoforming, and more particularly to the use o~ semi-permeable ~ilms and coatings use ul for providing a release mechanism from photoformed layers during the formation process.
The readers appreciation and understanding of the inventions described herein will be enhanced by reference to the draw~ngs and a description of the drawlngs and operation described below.

~3'3'.~'7 In reference now to Figure 1, there is provided a semi-permeable fllm 102, having first and second surfac~s, positioned in a photoformable composition 104 by tenter frame 106 in such a manner that the film second surface 102" is in contact with the photoformable composition 104 and the film f~rst surface 102 5 iS facing ~way from the composition 104. The film 102 is held to a particular shape ~y placing it in a tenter frame 106. A deformable-coatlng-mixture 110' with a dissolved inhibitor 1~2' is introduced on the film first surface 102' side. Also,.a permeated-deformable-release-coating 110 with a permeated inhibitor 142 is between the ~ilm second surface 102" and a photoformable-composition-layer 112. This photoformable-composition-layer 112 may contain different concentrations than that of photoformable composition 109 due to, for example, dissolved inhibitor 142' diffusing through the semi-permeable film 102. For the purposes of this i.nvention, a deformable release coating shall mean a coating, of one molecular thickness or more, that is a gas, a liquid, and/or a gel such that its shape may be changed by the application of pressures or forces. Similarly, a-photoformable composition is a material which is a liquid and/or a gel, which may con~ain dissolved gases, and which, photoforms, hardens or increases in viscosity when exposed to appropriate sources of radiation. A radiation source 119 illuminates specific regions of photoformable-composition-layer 112 through a photomask 116 causing the photoformable-compositlon-layer 112 to harden. After photoformable-composition-layer 112 is photoformed, creating photoformed layer~s~ 122, radiation source 114 is turned off or shuttered and tenter frame 106 and film 102 are slid from the surface of photoformed layer 122 by frame assembly translation means 11~ ~shown ln Figure 1 as an arrow for the ~ake of simplicity~. Then the platform 120 and the previously photo~ormed layer~s) 122 are translated 2~2~

at least one photoPormable-composition-layer th~ckness relative from the original surface o~ film 102 and permeated-de~ormable-release-coating 110 by platform translation means 124. After the previously photo~ormed layer(s) 122 have been translated by platform translation means 124, frame assembly translation means 118 moves the film 102 and tenter frame 106 back i:nto substantially it's original positlon, moving aside photoformable composition 104 and forming a new photoformable-composition-layer 112.
This process is continued until the desired three-dimensional ~bject is imaged. In the embodiment shown in Figure 1, ~he photoformable composit;1on 104 is contained in a vat 12~. The photof~rmable composlt$on 109 forms a composition/atmosphere interface l53. Above this composition/atmosphere interface, ~here is a composition atmosphere 152. Above ~he film 102 held to a shape by the tenter ~rame 106 and the deformable-coating-mixture 110', there is an imaging atmosphere 156 which may be di~ferent from the composition atmosphere 152.
Figure 2 depicts a preferred embodiment of the instant invention. In this embodiment there is a semi-permeable transparent film 202, having first and second surfaces~
with the film second surface 202" facing the photoformable composition 204 and the film first surface 202i facing a transparent plate 232. The transparent plate 232, having ~irst and second faces 232' and 232" respectlvely, has the first plate face 232' facing the composition 204 and the second plate face 232ll facing away from the composition 204. ~he ~ilm 202 ls stretched to conform to the shape of the plate 232 and both film 202 and plate 232 are secured in a frame 207, which also serves as a composition 204 vat, by compression $1ange 234 using securing means ~screws, levers, etc. not shown for clarity~ such that the film 20?
and plate 232 are sealed and the photoformable composition 2 ~3 ~ J; ~j 204 does not leak from the frame 207 between the film 202 and the frame 207, and pressures can be maintained without leakage betwee~ the ~ilm 202 and the plate 232. A
deformable coat~ng-mixture 210' is introduced between the film 202 and the plate 232 through flrst tube 230' and second tube 230" which are sealed to ~he plate 232 in a manner adequate to prevent leakage. First and second tubes 230' and 230" are connected respectively to a first replen~shment assembly 254' and a sec:ond replenishment assembly 254n, each of which comprlse respectlvely a porous tube 238, a tube screen 240, ~ concentrated inh~bitor 242", dissolved inhibitor 242', tr~nsfer solutlon 211, a fla~k 296, and an inhibitor supply 244. The porous tubes 238 in ~irst and second replenishment assemblies 254' and 259" are connected to each other through flexible tube 25B. The flexible tube 258 is squeezed by squeeze roller 236 against a portion o~ frame 207 in such a manner that the flexible tube 258 ~s divided preventing the deformable-coating-mixture 210' and any dissolved inhibitor 242' from flowing through the squeeze point 237. The deformable-coating-mixture 210' along with dissolved inhibitor 242' permeates through the film 202 forming a permeated-deformable release-coating 210 with permeated inhibitor 242 on the film second surface 202" betweea the film 202 ~nd the composition 204. In plate 232 there is a rec~ss region 228.
Wedge 298 is secured in this recess reg$on 228 in such a manner as to divide the film 202 secured between the plate 232 and frame 207 into tw~ chambers, first chamber 250' and second chamber 250". Above the frame 207 there is a composition atmosphere 252. The fr~me assembly (comprising frame 207, plate 232, first and ~econd chambers 250' and 250n, composition 204, compre sion flange 234, first and second tubes 230' and 230", recess 22B, wedge 248 and portions of flexible tube 253) are moved relative to t~e squeeze roller 236 the rad$ation source 214, the photomask 216, the photofor~ed layers 222, the platform 220, and the platform translation means 224, in a direction substantially parallel to the first plate face 232' by frame assembly translation means 218. Platform translation means 224 translates the platform 220 and any photoformed layers 222 in a dixection substantially normal to the first plate face 232'. When the platform 220 or previously photoformed layers 222 creates a region of photoformable composition 204 one layer thickness between ~he plat~orm 220 or ~he photoformed layer~s) 222 and the permeated-deformable-release-coating 210, ln preparation ~or exposuxe by radiation source 214 through photomask 216, a photoformable-composition-layer 212 exists. ~his photo~ormable-composition-layer 212 may contain different concentrationS than that of photoformable composition 204 due to, for example, dissolved gases or inhibitors 242 diffusing through the coating 210 into photoformable-composition-layer 212.

The operation of the apparatus in Figure 2 is as follows:
Photoformable composition 204 is placed in the frame 207. It is not necessary that frame 207 be leveled, relative to earth's gravity, except to prevent the 25 composition 204 from flowing over the ~rame ~07 sides. It is only necessary to provide enough composition 204 in frame 207 to ensure that a complete object can be made and that composition atmosphere 252 bubbles are not introduced between the platform 220 and the plate 232 during 30 translation by translation means 218 or 224. If necessary, photoformable compo~ition 209 refill means ~not shown) may be provided. Chambers 250' and 250" are filled with deformable-coating-mixture 210' and dissolved inhibitor 242' in a manner such that when one chamber, for example 35 ~irst chamber 250', has the deformable-coating mixture 210' and dissolved inhibitor 242' being drawn from it, second chamber 250" has the deformable-coating-mixture 210' and dissolved inhibitor 242' entering it. This is due to the pumping action of squeeze roller 236 rolling and squeezing flexible tube 25B against frame 207 as frame assembly translation means 21B translates the frame assembly (comprising items described above), thereby changing the volume of flexible tubing 25B connect:ed as described above to first and second chambers 250' ancl 250". As shown, therefore, as the frame assembly tcomprisi~g items described above) is translated by ~rame assembly translation means 218 to the right, slqueeze roller 236 squeezes and reduces the volume of flexible tube 258 connected through second replenishment assembly 254" and second tube 230" to second chamber 250". The deformable-coating-mixture 210' and dissolved inhibitor 242' thereby flows into second chamber 250" causing it to bulge. In the preferred embodiment, film 202 is elastomeric and therefore is capable of bulging or flattening without permanent deformation. On the other side, while the frame assembly tcomprising items described above) moves to the right, the volume, in flexible tubing 25B connected through first replenishment assembly 254' and first tube 230' to first chamber 250', increases, thereby drawing deformable-coating-mixture 210' and dissolved inhibitor 242' ~rom the first chamber 250' and causing the film 202 to flatten on this side. As the frame assembly (comprising items described above) is moved to the left the volume changes~
the deformable-coating mixture 210' flow, and the bulging/flattening relationships between first and second chambers 250' and 250" would be reversed. As the frama assembly tcomprising items described above) moves and pumps the deformable-coating-mixture 210' and dissolved inhibltor 242' into or out of the first and second chambers 250' and 250" the deformable-coatin~-mixture 210' and dissolved 2 ~ 'J~J~

inhibitor 242' pass through the, first and second replenishment assemblies 254' and 259" respectively Within said first and second xeplenishment assemblies 254' and 254", a porous tubing 23B contains the ~low of coating S mixture 210' and 292' while allowing concentrated inhibitor 242" to pass by diffusion means into the deformable-coating-mixture 210'. ~he porous tubing 238, further described later, is such that it can substantially contain a relative pressure but may collapse when containing a relative vacuum. The tube screen 240 prevents ~he collapse of porous tuhing 238 when a xelativ~s vacuum is being maintained. Since during the photoformation process further described, permeated inhibitor 242 :Is consumed, there will be diff~sion of dissolved inhibitor 242' through the film 202 from the de~ormable-coating-mixture 210' thereby decreasing its concentration of dissolved inhibitor 242'.
In the replenishment assemblies 254' and 254" inhibitor : supply 244 maintains the concentration of concentrated inhibitor 242" at a relatively high level in the transfer solution 211 within the flask 246. Therefore, diffusion and the flow of deformable-coating-mixture 210' and dissolved inhibitor 242' (due to volume changes in ~lexible tubing 258 as described above) through porous tube 238 causes the concentrated inhibitor 242" to replenish the low ooncentration of dissolved inhibitor 242', which in turn permeates through film 202, replenishing the concentration of permeated inhibitor 242, and which in turn diffuses into the photoformable-composition-layer 212.

In preparation for making photoformed layer(s) 222, for example, the frame assembly (comprising ltems described above) is moved to the right by frame assembly translation means 21B such that platform 220 is facin~ a flat region of the plate first ~ace 232'. The plat~orm 2?0 is translated by platform translation means 224 to a position such that a photoformable-composition-layer 212 ls formed. Radiati~n source 214 and photomask 216 are positioned uch that they can shine substantially collimated illumlnation, through the plate 232 (~he reader should understand that the only thing substantially limiting illumination of the plate 232 by radiation source 214 is photomask 216.), ~eformable-coating-mixture 210' and dissolved inhibitor 242', film 202, and permeated-deformable-release-coating 210 and permeated inhibitor 242, into photoformable-composition-layer 212. An imagewise exposure ls made that issubstantial enou~h ~o create a photoXormed layer 222 portions of which substantially adhexe to platform 220.
Preferably platform translation means 229 translates the platform 220 and any attached photoformed layer 222 the distance of one photoformable-composition-layer away form plate 232. This usually causes the film 202, the permeated-deformable-release-coatin~ 210, the permeated inhibitor 242, the deformable-coating-mixture 210', and dlssolved inhibitor 292' to substantially rise also, overcoming the relative vacuum formed in flexible tubing 258. Next or simultaneously, ~rame assembly translation means 21~
translates the frame asse~bly (comprising items descrlbed above) to the left. As this occurs, portions of photoformed layer 222 reach the edge of recess 228 where the film 202 and permeated-deformable-release-coating 210 substantially separate from the photoformed layer 222. Photoformable composition 204 flows with substantial ease throu~h recess 228 to fill the gap at the s~paration line between the photoformed layer 222 and f~lm 202. ~hen the photoformed layer 222 passes over the r~ght edge of rec~ss 228 a new photoformable-composition-layer 212 is created above ghe second chamber 250". As this occurs, second chamber 250"
collapses (for reasons described above) causing film 202 and the coating mixtures to conform to the subs~antially flat shape of plate 232 in this region. From this point, ~ ,~3 3 ~ 2 '~

another lmagewise exposure can be made substantial enough to adhere portions of the newly photoformed layer 222 to the previous photoformed layer~s) 222. ~he process above can be repeated, coating photoformable composition 204 on one side and exposing imagewise on the same side then separating the photoformed layers 222 from the film 202, etc. until all photoformed layers 222 bave been ~abricated necessary for the production of an object.

It is preferred that the film be impermeable to the photoformable composltlon and substantially inert to it. The impermeability prevents the composltion from passing from the composition contacted surface of the film to the other sur~ace, or into the pores of the film , wher~
the radiation would photoform it. Examples of uch films may be composed of polypropylene (such as, f or example, film manufactured by Hercules Inc. Wilmington DE), Teflon PFA~, Teflon TFE~ tsuch as, for example, manufactured by E. I. DuPont De Nemours Inc., Wilmington DE), or polyethylene, etc. or any of a number o polymer and copolymer films. Some films such as, for example, molecularporous ~embranes ~such as, for example, those manufactured by Spectrum Medical Industries, Los Angeles, CA), may prove suitable for some applications of the invention in that they have a known pore size that allows molecules of low molecular weight to pass through the film while molecules of size larger than the pore size cutoff are prevented from passing through the ~ilm. For such an application, it would be desirable for the molecular size of the composition to be larger than the pore size and for the molecular weight of a deformable-coating-mixture (such as will be described later) and diffused inhibitors to be of smaller molecular size than the pore size. In this case, a deformable-coatlng-mixture can pass through the film by, for example capillary action. In the case of Figure 2, the L 2 7 ':~

preferred porous tubing 23B is, for example, Spectra/Por molecularporous membrane tubings which have molecular weight cutoffs in the range of 100 to 500. These porous tubes 238 can withstand fairly high pressures and are capable of diffusing concentrated inhibitors 242", for example concentrated oxygen, without substantially diffusing the trans~er solution 211 or deformable-coatlng-mixture 210'. Still more preferable is a film that is o~
substantially different molecular po.larity than that of ~he photo~ormable composition or ~hat of the photo~ormed layers such that the composition and the photoformed layers tend not to wet the film . This is advant~geous for ~everal reasons: ~ack of wetting of the film by the composition decreases the potential for bondin~ to the film during photoforming of the composition. And, since all ~ilms are porous to some degree or molecular size, lack of wetting by the composition significantly decreases its permeation of the film since surface tension effects tend to prevent the composition from entering or passing through the pores.
(Such art is the basis of many products, for example, Gore-tex~ manufactured by Gore Associates Inc., Newark, DE.).
Rreferably, the film is held submexged in the photoformable composition and held substantially to a particular shape, preferably substantially flat, by placement of a transparent plate against the film surface that is opposite the photoformable composition. In the preferred mode, shown in Figure 2, in which ~V light is the preferred radiation source 214, the plate 232 usually is made of, for example, quartz, fused s$1ica, waterwhite glass, or any other material that is substantlally transparent to the wavelength in use and has substantially good optical qualities. For other forms of radiation such as, for example, microwave or dielectric excitation, plastics or even metals may provide suitable plate material if they are substantially transparent to the radiation and 2 ~ 3 if they induce substantially low distortion of the electromagnetic fields. Or, as in the case of Figure 1, the film 102 may be held to a particular shape by use of a tenter frame 106, or the film 102 may even possess the desired shape and necessary st~ffness to ~bviate the need for a frame 106. For the purposes of this invention, referring now to Figure 2, a substantially ~lat plate 232 ln contact with the film 202 i5 preferred, however, the plate 232 may have any curvature that allows sliding of the ~ilm 202 from the photoformed surface 222 and does not create damaging vacuum forces between the f~lm 202 and the photoformed layer 222 during the sliding action. The film 202 15 preferably pulled by vacuum means (combination of 218, 236 and 258 as described above) to ensure it conforms substantially to the shape of the plate 232 it contacts.
The plate 232 may be of any useful size necessary for the production of large or small photoformed layers. The plate may also be, for example, an optical fiber.

For the purposes of the instant invention, it is preferred that the film be an elastomeric film since such films conform more readily to the shape of any desired surface and these films, such as, for example, silicone, tend to have high diffusion coefficients even though the moiecular size of the penetrant molecule is greater than the pore or hole si7e~ A penetrant molecule can often temporarily expand holes in films ~f the films have polymer chain mobility. Thus the penetrant can move the polymer ~hains aside and squeeze through the expanded holes or pores. Elastomeric films typically have even greater ehain mobility enhancing the ability of the penetrant to expand the holes and therefore ~ncreasing the di~fusion of the penetrant. Further enhancing this pen~tration ls the presence of a plasticizer, such as ~or example a deformable-coating mixture, which increases the film chain mobility and creates swelling, thus allowing easier permeation of the penetrant through the film.

Preferred elastomeric films are, for example, transparent silicone elastomers and fluoroelastomers, such as for example clear Kalrez~, sold by DuPont. ~ost .
preferable are fluoroelastomers such as, for example, the ones described in DuPont's cs-pending application AD-5724, which is herein incorporated by reference. A ilm ~f th~ 5 type, which was extensively used during this wor~, was prepared as follows:
~A) a 10 gallon stainless steel autoclave was evacuated and purged with nitrogen and then was charged with 2600 liters of deionized, de-oxygenated water containing 1.5 liters of Freon 113 ~1,1,2 trichloro, l,2,~ trifluoro e~hane), and in which was dissolved 56 g. of ammonium perfluorooctanoate surfactant (FC-143, ~M Co.). The reactor was then pressured to about 0.2 MPa (30 psi) with the "start-up monomer" mixture which had the followin~ composition:
30% by weight TFE (tetrafluoroethylene) and 70~ ~y weigh~ PMVE (perfluoro tmethyl vinyl ether)). The autoclave was vented off to about 0.03 MPa (5 psi).
The pressuring and venting was repeated 2 more times.
At this time, 3.6 g of 1,4 diodoperfluorobutane, dissolved in 36 ml of 1,1,2 trichloro 1,2,2 trifluoroethane, was added, and the autoclave was heated to 80C. while stirring at 125 rpm. The autoclave was then press~red to 2.1 MPa ~300 p~i) with ~he "start-up monomer" mixture described ~bvve. To start the polymerization, the autocla~e was charged with 20 ml of a 2~ solution of ammonium persulfate in water. After the pressure in the autoclave had decreased to about 2.0 MPa ~295 p~i). The au oclave was maintained at a pressure of about ~.1 MPa (300 2 ~ $

psi), during the course of the polymerlzation, by regular addition of the "~ake-up monomer" mixture. The "make-up monomer" mixture had the following composition: 46% by weight TFE, 8% by weight ethylene, and 4 6% by weight PMVE. The polymerization was allowed to continue for a total of 15 hours during which ime 6500 grams of the make-up monomer mixture was added.
Also, during this period an additional 129 ml of 14 ammonium persulfate was ~dded in small increments. The unreacted mo~omers were vented from the ~utoclave and the polymer dispersion was discharged lnto a large container. The pH of the dispersion was 2.7 and it contained 20.7~ solids.

The fluoroelastomer was is~lated from 500 ml of the above dispersion by coagulating with potassium aluminum sul~ate solution. The coagulated polymer was separated from the supernate by filtration and then washed 3 times by high speed stirring in a large blender. Finally, the wet crumb was dried in a vacuum oven at 70C for 90 hours. The recovered, dry polymer from the 500 ml aliquot weighed 114 grams. The composition of the ~luoroelastomer was as follows: 4S%
by weight TFE, 6.8% by weight ethylene, and 38.2% by 2S weight PMVE. The polymer contained 0.22~ iodine and had a Mooney viscosity, ML-lO, measured at 121C. of 32.
~B) A 10 gallon autoclave was charged with 30 Xg of - the polymer dispersion prepared in ~A) above. The autoclave was then e~acuated and purged 3 times with nitrogen, then 3 times w~th a new "start up" monomer mixture of the followin~ composition: 90~ by weight TFE nd 104 by weight ethylene. The autoclave was then heated to 80C and pressured to 1.3MPa 1190 psi) with the new "start-up monomer" mixture. The polymerization p~ ~

was then initlated by addition of 20 ml of 1% ammonium persulfate solutlon. The pressure wa~ kept constant by addition of a new "make-up monomer" mixture which had a composition of 80% by weight TFE and 20~ by weight ethylene. A total of 1050 g of the new "make-up monomer" mixture ~as added in a 4.3 hour reaction time. The monomers were then vented off and the segmented polymer dispersion was discharged from the reactor. The dispersion containecl 26.8% solids. The segmented polymer was isolated from the dispersion ln the same manner as described for the fluorelastomer in ~A) above. A to~al of 8.3Kg of polymer was recovered.

Different~al Scanning Calorimetry testing on the segmented polymer indicated a glass transition temperature of -14~C for the fluoroelastomer segment and a melting point of 233C for the thermoplastic segments. The iodine content of the polymer was 0.13%.
The melt index ~ASTM D-2116 using a 5 kg weight at 275C~ was 3.0 g/lO min.

A compression molded film of the polymer had M100 (modulus-at ~00% elongation) of 3.4 MPa (500 psi), tensile strength ~break) of 23.4 MPa ~3400 psi) and elongation (break) of 380%.

The fluffy polymer recovered according to the above procedure was extruded into beads (approx. 3 mm X 6 mm) in a 28 mm twin screw extruder at 2S0C under nitrogen. The same type of extruder was then used at 300C under ~itrogen to extrude a film through a slit die on a casting drum. ~Ae film thickness was 0.0115".

The Applicants suggest that an understanding of the following proposed concepts will give the reader an r~

appreciation of the novelty and advantages of their invention. However, these proposed concepts should only be taken as suggestions to the reader, and by no means, should the Applicants' proposal~ be construed as limitin4 in any way the breadth and scope of this invention.

A material which is in contact with a photo~ormable composltion during exposur~ might interfere with the cross-lin~ing. If the material, for example, a Teflon~ film or a nitroge~ atmosphere, is substantially inert to the photo:Eorming pxocess ~nd is the only material ln contact with the composition at the time of the exposure, it is :Likely that ~he composition will cross-link to a significant degree.
~he degree of cross-linking is limited by, 40r example, the presence of an inhibitor in the composition, the lack of adequate radiation, an improperly mixed formulation, etc. However, assuming all these conditions are not present, the degree of cross-linking is often limited by, for example, the change in mobility of radicals within a i~creasingly more viscous matrix. This is ~o say that even under the most ideal conditlons, the degree of cross-l$nk~ng of, for example, a photoformed layer is often by nature incomplete. This incompleteness of cross-linking or presence of act~ve sites, if it exists on the surface of a photoformed layer, may provide potential cross-link~ng sites to which a subsequent photoformable-composition-layer may bond (by cross-linking~. However, a ~reater degree of cross-linking or a lesser number of acti~e sites on the surface of a first photoformed layer, provides fewer cross-linking sites for the bonding of subsequent photo~ormed layers to the first layer by oross-iink~ng means. Therefore ~t is reasonable to assume that a film, ~r example 7 i~

Teflon~, or an imaging atmosphere, for example nitrogen, which is substantially inert to the cross-lin~ing, but by it's presence in contact with the photoformable composition during exposure, tends t~
prevent inh.ibitors ~rom ~ontacting the composition during the exposure, will allow a greater degree of cross-linking, and therefore fewler active cross-linking sites to which subsequent photoformed layers might adhere. In short, an inert material, whether a gas, a liquid, a gel, or a solid, ln contact with a photoformable composition during exposure, may signlficantly interfere with the photoformed layer's ability to cxoss-link to subsequ~ent photofoxmed layers.
If, on the other hand, a substantially inert film, for example the above fluoroelastomer, or a permeated-deformable-release-coating, such as for example FC-40 ~described later), or an imaging atmosphere, which allows the presence of an inhibitor to be in contact with the photoformable-composition-layer during exposure, is utilized, there will be a lesser degree of cross-linking at the interface and there may be more active sites present to which subsequent layers may bond. It should be understood that the imaging atm~spheres described may contain an inhibitor, such as ~or example oxygen. An inhibitor, whether from the atmosphere, inherent in the coatings, or inherent in the formulation of the photoformable composition, is free to diffuse into the compositlon and change the compo5ition concentration. The presence of inhibitors typically decrease the degree of cross-linking by, ~or example, quenching sn initiator or quenching a radicalized monomer. In many cases, the quenched initiators or quenched radicali~ed monomers 2~ 2s~

are at least partlally no longer available to participate in a photo reaction. Therefore, quenched monomers immediately a~ an interface, where the inhibitor concentration is the highest, for example, at the interface of the permeated-deformable-release-coating within the photoformable-composition-layer, are likely not to be cross-linked nor are they usually considered to be active sites for subsequent bonding of new photoformed layers.This lnhibited inter~ace has been substantially reduced in ability to su~sequently cross-link. (This interface also is still nicely deformable, aiding in the relea~e from a film and aiding in ~ubsequent coating.~ However, if we consider a region ~ust slightly ~urther away from the interface within the compositlon, where the concentration o~
inhibitor ls lower (due to lower concentration of inhibitor in the photoformable composition as a whole, and due to oxygen consumption at the interface of the photoforming composition layer during radicalJinitiator quenching and subsequent diffusion effects of oxygen toward the interface from the remainder of the photoforming composition layer), ~he degree of cross-linking is increased due to a reduction in ~nhibitor quenching of initiator and radicalized monomer. But there is also a greater degree of future active sites because the interface of the photoforming composition layer absorbed some of the radiation and allowed less production of radicalized initia~or and radicalized monomer ~o be formed during the exposure in the remainder of the photoforming composition layer. As we consider regions further and further away from the interface, in the photoforming composition layer, the same trends cont~nue; greater degree of cross-linking due to fewer quenched radicals, and fewer radicals formed providing 2 ~ 2 r~ ?3 more future active sites. Also, as we consider re~ions further and further away from the inter~ace, in the photoforming composition layer, the amount of quenched monomer and therefore the amount of deformable composition (though no longer considered to be photoformable composition in many cases) becomes less and less causing a relatively gxadual transitlon from deformable compos~tion to photoi.ormed layer. This gradual transition is very useful slnce lt precludes chemical bonding and mechanical bondins at the interface of the photoforming compositlon layer and aids in reduction of vacuum forc:es that may arise during the removal of the film irom the photoformed layer. And this gradual transition is also useful since there is now a substantially greater surface area of potential cross-linking sites and mechanical bond sites connected to the photoformed layer to which subsequently applied and exposed photoformed layers may bond, thereby increasing the layer to layer adhesion in the formed object.

It is an important distinction in this invention that the films and coatings, which are substantially inert relati~e to, and which are immiscible in, the composition~ whether photoformabla or photoformed, nevert~eless allow the supply of permeated inh~bitors through them into the composition, and therefoxe can aid in both release of the photoformed layer from the films and subsequent bonding of new photoformed layers ~n regions substantially away from the film/coating/composition immediate interface.

The importance of the composition atmosphere in contact with the photoformable composition becomes more apparent when a semi-permeable film that employs, 2 ~

for example, oxy~en diffusion is utillzed. For example, if the composition atmosphere is pure nitrogen, it is reasonable to assume that the photoformable composition contained in the vat on average contains less oxygen than normal, assuming equilibrium conditions. It is also reasonable that the photoformable-composition-layer will have a sharper increase in the amount of dissolved oxygen as the semi-permeable film which diffu;es oxygen is approached. And it might be expected that the photoformed layer would also display a sharper decrease in degree of cross-linking 8S the film ls approached. Therefore control oi the components o~ the composition atmosphere, control of inhibitors in the lS coatings, and/or control of the imaging atmosphere, which all affect the concentration of inhibitor within the photoformable-composition-layer, are important elements that affect the degree of bonding of one photoformed layer to another and the ability of a photoformed layer to be separated from another ma~erial through which it was exposed while in contact.

While it is preferred that the composition atmosphere be, for example, nitrogen, this in most cases is harder to control. It is possible to contain the entire apparatus in an enclosure and to control the eomposition atmosphere to any desired extent. Such a apparatus could, for example, blow air and, for example blow extra nitrogen or oxygen into the enclosure using a conventlonal blower and regulated tanks of gas. This might be useful, since with most photofDrmable compositions when exposed using conventional methods ~ie. exposing the photoformable composition without the use of a film or transparent plate) the extra nitrogen in the composition atmosphere will : ~542 ~.3 increase the photospeed of the composition, or th~ extra oxygen in the atmosphere would improve interlayer adhesion In addition the composition atmosphere could be changed during exposure ~e.g. the composition atmosphere might comprise roughly 95% nitrogen, 5~ oxygen before exposure, and the imaging atmosphere could be changed to comprise roughly 75% nitrogen, 25% oxygen dur:Lng exposure) to obtain a sharper transition from photoformed layer to deformable composition ~as described above), ~nd therefore have higher photospeed yet good photo~ormed layer adhesion. It is more preferred, however, that the composition atmosphere be air and that the concentration of permeal;ed inhibltor in the permeated-deformable-release-coating be higher than that normally found in air.
Studies were conducted, by the Applicants, with several films, Mylar~ polyester, fluoroelastomer ~described above), polyethylene, Teflon PFA~, and Kalrez~
to determine if there was an inherently inhibiting effect on photoformable compositions exposed in contact with and through the films. The tests were conducted with the film in contact with the photopolymer on one side and air or nitrogen, as the imaging atmosphere, on the other side.
Exposures were made with a mercury arc lamp rom the film/atmosphere side into the photopolymer. In most cases where air was the gas on one slde of the film, the hardened layer of photopolymer was substantially softer at the interface between the film and the photopolymer layer produced. In cases where nitrogen was the gas on one side of the film, the interface between the film and exposed photopolymer was more hardened. This indicates that the film materlals themselves may not inhibit the cross-linking ability of the photopolymers exposed in contact with the film, but that it is the presence of a$r or, more probably oxygen, which permeates through the film and inhibits the ,~ 2 ~ ~ L~

cross-linking abillty of the photopolymer at the film inter~ace during exposure.

Additional studies were performed, by the Applicants, that appear to support the conclusion that i~ is permeation of air through the film during exposure that inhibits the cross-linking ability of ~he photopolymer, rather than the molecular structure or inhesent inhibi~ing effect of ~he film. Samples were prepared using a pho~opolymer which consisted of a formulation as detailed in DuPont's patent application Serial No. 07 341,347 (dated April 21,19891 "Solid Imaging Method U in~ Compositions Contaln~ng Core-Shell Polymers", Example 2, hereinafter referred to as TE-1541. The ~amples were exposed using an Ultracure 100 mercury arc lamp source manufactured by Efos Inc. of Mississauga, Ontario, Canada. The output of the light was filtered through a Corning 7~51 filter which allows transmission of light from the lamp in a range of UV
centered around 365 nm. Exposures were given for around 10 seconds o~er an area of about 2.5 in. diameter. Each sample was exposed with one surface of the following materials, wetting the photopolymer and the other surface of the materials exposed to an imaging atmosphere. The materials tested were 1.0 mil polyethylene film, 1.5 mil Teflon PFA~
film, 11.5 mil fluoroelastomer film 3as described above), 32 mil Kalrez~ film, Teflon AF~ coated quartz, Fluorinert~
FC-40 (perfluorocarbon) liquid, or water. Each sample was exposed with an air imaging atmosphere or a nitrogen imaging atmosphere on one side of the above materi~ls.
After exposure, the layers of photopolymer were removed from the above materials, keeping track of the layer surface in contact with the ~ilm, and cut in a strip of si2e appropriate for pexforming an IR reflectance analysis using a BIO-RAD, Digilab Division, FTS-60 Fourier Transform Infrared Spectroscopy in reflectance scan mode. The photoformed layer samples were placed with the film interface side contacting a KRS~5 ~Thallium Bromo-Iodide) crystal in a ATR-IR (Attenuated Total Reflectance) accessory used for measuring the spectroscopic reflectance.
In reflectance mode, this instrument is capable of output~ing the spectra of the surface of a sample, ~rom which the de~ree of conversion (polymerization or cross linking) of the sample sur~ace ean be determined. The degree of conversion can be determinecl by comparing the ratio of a speciflc wavenumber peak he:ight above baseline, which peak heiyht is known to change wlth degree of conversion, to another wavenumber peak height above baseline, which is known to be substantially unchanged by the degree of conversion. In the case of TE-1541 photopolymer, the peak height ~above baseline value) of, for example, 811 wavenumber decreases with greater polymerization and the peak height (above baseline value) of, for example, 1736 wavenumber is substantially unchanged by the amount of polymer conversion or polymerlzation.
Therefore, in evaluating the ratio of the peak height of 811 wavenumber to the peak height of 1736 wavenumber, a decrease in value of this ratio indicates that a greater degree of conversion occurred. As an item of comparison, the unexposed monomer (TE-1541) was also tested using ~he above evaluation method.

2 ~ 7 ~

Followin~ are the rankings in the test with the ranking from the most conversion to the least conversion:

Polyethylene Film-Nitro~en .143 Teflon PFA~ Film-Nitrogen .185 Fluoroelastomer Film-Nitrogen .197 Teflon AF~ on Quartz-Nitrogen .211 Water-Air .212 Water-Air .245 Teflon PFA~ Film-Air .252 Mylar~ Film-Nitrogen .259 Water-Nitxogen .259 Kalrez~ Film-Nitrogen .337 Fluorinert~-~ir .359 Teflon AF~ on Quartz-Air .362 Polyethylene Film-Air .376 Fluorinert~-Nitrogen .379 Kalrez~ Film-Air .420 Mylar~ Film-Air .473 Fluoroelactomer Film-Air .477 Unexposed Monomer ~TE-1541) .518 .
As can be seen from the above ranking, the surface of a layer exposed through a film that has nitrogen as the imaging atmosphere nearly always shows a greater degree of conversion than does the same film if air is the imaging atmosphere. Water, with air or nitrogen as the imaging atmosphere, shows little difference in degree of conversisn since relatively little oxygen is soluble in water in the natural state. And in fact, the evaluations made with water tend to indicate the amount of error present ln the test.
The samples tested with Fluorinert~ liquld also show ~ery little difference whether the lmaging atmosphere ~s air or nitrogen. It is believed that this is due to the fact that ~ 9 Fluorlnert~ has a special afPinity for oxygen and the oxygen must be removed using stronger measures than ~ust placing the liquid in a nitrogen imaging atmosphere for an hour or so. ~owever, independent of error, a general ranking may be ~btained from the evaluation giving a good indication that the imaging atmosphere on one side of a film permeates through the film and affects the degree of conversion of the photopolymer durlng exposure. It is also important to note that the fluoroelastomer film, whlch ls the most preferred film for the purposes of this invention, having an imaging atmosphere of air, c:reates an exposed photoformed layer surface ad~acent to the film with the lowest degree of conversion ànd exhibi.ts th~ greatest difference in degree of conversion when an exposure is made in a nitrogen imaging atmosphere. This suggests that the fluoroelastomer film has the greatest permeability to oxygen of all films tested, yet with substantially no inherent inhibition or effect on cross-linking of the contacting photopolymer being exposed. That is, the film material is substantially inert to the photoformation of the composition, however, it's ability to be permeated by, for example, oxygen, or it's readiness to allow oxygen to diffuse through it, provides a substantially inhibited surface of deformable composition at the interface between the film and exposed photoformed layer, whlch in turn allows easier removal of the film by, for example, sliding means, or for example, peeling means. Essentially, the inhibited composition at the fluoroelastomer film sur~ace, when inhibited ~y permeated oxygen, becomes a deformable-composition-release-coating.

In the case of Figure 2, ~t is preferred that, a transparent deformable-coating-mixture 210', preferably a liqu~d but poss$bly a ~el, be introduced between the plate 232 and the film 202 to ensure good optical coupling r~ l~ 2 r~

between the two. Even more preferable is a deformable-coatlng-mixture 210' that permeates the film 202 and/or is plastici7er of the film 202. And still more preferable is a deformable-coating-mixture 210' that is of substantially similar molecular polarity to that of the film 202 while being of substantially dissimilar molecular polarity to that of the photoformable composition 204, photoformable-composition-layer 212, and photoformed layers 222. Also, it is more preferable that such a deformable-coating-mixture 210' be of substantially low viscosity and have substantially good lubricity. It is more preferred that such a deformable-coating-mixture 210' be the same mat~rial as the permeated-deformable-release-c:oating 210. And still more preferable that such a deformable-coating-mixture 210' tend to be transferred from the film ~irst surface 202' to the film second surface 202" by diffusion, whereby diffusion effects replenish the permeated-deformable-release-coating 210 on the film second surface 202" should the concentration of the permeated-deformable-release-coating 210 become diminished, and whereby diffusioneffects no longer cause transfer of deformable-coating-mixture 210' once the concentration of coatin~ is substantially the same on both *he film first surface 202' and the film second surface 202". It is in the preferred case that diffusi~n provides the driving force or pressure for the deformable-coating-mixture 210' to pass through the film 202. Another pre erable route would be for osmotic pressure to provide this driving force. Even more preferable, is a film 202 which is permeable to, for example, air or oxygen (or other inhibitor, whether as a gas or more preferably dissolved in solution with the coating), whereby an inhibition of photofQrming cf the photoformable-composition-layer 212 occurs at the interface between the permeated-deformable-release-coating 210 and the photoformable-composition-layer 212, and a little beyond, leaving the photoformed layer 222 deformable at this interface and forming a deformable-composition-release-coating, even after exposure, further decreasin~
any chemical, mechanical, hydrogen, or like bonding, and therefore provlding easier sliding o~ the film 202 from this interface after exposure. It is also preferred that air or oxygen, or other permeated inhibitor 242, be substant$ally dissolved ln the permeated-deformable-release-coating 210 and that the deformable-coating-mixture 210' aid in transfer of the air or oxygen, or other dissolved inhibitor 242', through the~ film 202 by dlffuslon means. It has been shown, by others ~amiliar with the art of diffusion, that gases penetrate more readily when they are more condensable and soluble in a liquid, especially in a llquid that permeates and swells a film. This swelling of the film, which increases the diffusion of the ~eformable-coating-mixture, and in the preferred case, increases the diffusion of soluble oxygen in the deformable-coating-mixture, thxough the film, is a different transport mechanism from just capillary action, as might occur through, for example a p~rous fused silica plate, which is not capahle of swelling.

The presently preferred deformable-coating-mixture which has all the above preferred properties, when used in combination with the preferred fluoroelastomer film, is Fluorinert~ FC-40 (3M, St. ~aul, Minnesota). Fluorinert~
Liquids are manufactured by electrolyzing an organic compound in liquid hydrogen luoride. The ~luorlnation is complete. FC-40 has a molecular weight of 650. Fluorinert~
is immiscible ln all photoformable compDsitions t~sted to date, however, it can contaln 37 ml of oxygen per lOOml ~f Fluorinert~ without affecting the optical clarity of the coating. ~he l$quid is very non-polar and therefore has hiyh surface tension when in contact with the typically ~$~2P~

more polar photoformable compositions. Xt permeates the film quickly. Preferably, the film is first saturated with the Fluorinert~ overnight, prior to assembly in the frame.
The Fluorinert~ has low viscosity and provides a slippery feel on the surface of the ~ilm. Referring to Figure 2, in the case of the transfer solution 211, FC-40 is preferred, however, other Fluorinert~ liquids, such as for example, FC-72 are more preferred since these liquids can contain a greater co~centration of oxygen and therefore enhance the diffusion of oxygen through the porous tube 238.

~ ollowing are the results of a test run with the preferred film and FC-40 in c~mbination with TE 1591:

Approximately 20 ml of ~C-90 was placed in a beaker. The fluoroelastomer film was stretched over the top of the beaker and clamped around the edges to form a drum. The beaker was then inverted, allowing the FC-40 to be fully supported by the film in the beaker. The beakex in this position was placed in such a manner as to immerse the film surface, outside the beaker, in another beaker of TE-1541.
The beakers were left in this position for several months.
Although FC-40 has a very high specific gravity of 1.87 at 25C, high surface tension when in contact with photoformable compositions, and immiscibility with these compositions, the FC-40 passing through the film never accumulated at the bottom of the TE-1541 beaker and never showed evidence of forming globules or drops.

~he Applicants' propose the following mechanisms as a possible explanation for the results obtained. However, this proposal is merely a suggestion, and it must be taken only as such by the reader. By no means should the Applicants' proposal be construed as limiting in any way 2 ~

the breadth and scope of this invention. The Applicants propose that:

The FC-40 wets and swells the ~ilm very easily.
Initially thexe is a high concentration of FC-40 on one side of the film. Since the film is permeable to the FC-40 and swelled by it, diffusion effects de~elop and transport the liquid to the other side oP the film which is in contact ~ith the composition. Since there are high surface tension effects between the FC-40 and the composition, the FC-40 tends to minimi~e ~t' 9 surface area forming a thin coating of liquid on the composition side of the film. This in turn creates a high concentration of FC-40 on the composition side of the film, thereby substantially equilibrating the concentration difference on either side of the film and diminishing any diffusion and transport effects.
In this way, it can be expected that only a thin coating of FC-40 will form on the composition side; If any of this coating should be sloughed off during the step of sliding the film from the surface of the photofoxmed layer, the diffusion will automatically refresh the permeated coating.

The above descri~ed self-replenishing release coatin~
method ha~ also been tested in conditions where the FC-40 and ~ilm were at the bottom. In either case, the FC-40 permeates the film and forms a coating on the composition side of the film, through which an exposure can be made ~o create a photoformed layer which can then be slid on the surface of the film. The significance of orientation of the assembly is an important point in the application of this invention. In the case described by the Applicants, a heavier liquid FC-40 was on top of the lighter l~quid photoformable composition. With this invention, the 7'j specific gravity of the liquid does not affect the desired results for oreating a release of a photoforn~ed layer from the surface of the film. That is, the invention's method of film orientation can be any method convenient for production of the layers or three-dimensional objects.

Any combination of film, composition and coa~ing material may conceivably be used in which 8 similar balance of propertles exlst. Many plastlcizers of films permeate the film and are transported through it by these methods.
And many of these combinations of photoformable composition, film, and deformable-co~ting-mixture may provide adequate performance in the production of photoformed layers and three-dimensional ob~ects.
Surprisinqly, use of ~ust an inhibltor, for example, air or oxygen, which permeates through a film without the presence of a coating may be used. ~or example, experiments have been conducted by the Applicants' that show that a film can be slid from a photoformed layer that has been exposed with a mercury arc lamp through the film. In the Applicants' test, the fluoroelastomer film s~id freely off an exposed Desolite SLR800~ ~DeSoto Chemical ~orporation, Des Plains, IL) photopolymer layer. The Kalrez~ film exhibited a little moxe adhesion but could still be slid from the surface. The polyethylene film showed more adhesion and ~ould not slide from the surface but could easily be peeled off. In each of these cas~s, the photopolymer s~r~ace at the film interface was slightly tacky.~An additional sample was tested using Teflon AF~
(DuPont, Wilmin~ton, DE) FPX/FC40 which had been eoated on sandblast frosted 1/8" thick frosted quaxtz plate with a spiral wound ~26 coating rod, then oven heated for about 12 minutes at 160-170 C to evaporate off the solvent. When the DeSoto SLR-800~ liquid was exposed ~hen ~n contact 2 ~ ~

with the Teflon AF~ coated side, sliding of the layer rrom the glass was not immediately possible, tThe Teflon AF~
has very low surface energy and is substantially inert, however, the sandblasted surface of the glass telescoped through the film creating a surface that provided ~ood mechanical bonds. In addition, dhering the Teflon AF~ to a quartz plate prevents oxygen from permeatiny to the interface between the Teflon AF~ and the photopolymer.) and the surface of the photoformed layer was not at all tacky. The Applicants suggest that the relative film adhesion and surface tack of the photoformed layers is substantially dependent on the tendenc:y of oxygen in ~ir to permeate the film and inhibit the photopolymer.

Referring to Figure 1, use of just a film 102 with an imaging atmosphere 156, such as or example, air or oxygen, which permeates through the film 102, diffuses into the photoformable composition 104, and which creates a deformable-composition-release-coating upon exposure is possible. (To the extent that these dissolved gases are photoformation inhibiting, the inhibited composition remains deformable after exposure and is therefore acting as a deformable-composition-release-coating.) Likewise, use of just a film 102 held to a particular shape, with a deformable-coating-mixture 110', and with or without an inhibitor 192' on the first surface of the film 102', which permeates ~he film 102 and creates a permeated-deformable-release-coating 110 (and/or a deformable-composition-release-coating) on the film second surface 102" -~s possible. Referring to Figure 2, when the film 202 is held to a particular shape by a plate 232, the deformable-coating-mixture 210' is preferred, in con~unction with dissolved inhibitors 292', since it creates substantially improved optical coupling between the film 202 and the 2 ~ s~jl plate 232 and therefore allows ~ormation of more precise photoformed layers 222.

It is possible to use a film that is only partially in contact with and partially adhered to a plate. For example, one surface of the plate may be sandblasted or in some way ~ave ~ roughened surface, and the film could be partially adhered to the plate by, for example, an adhesi~e, or, for example partial melting to the high spots in the plate. The fluorelastomer film would be particularl~ suitable for uch an application slnce it is a thermoplastic. With this method, the film sur4ace ~acing the co~position could be smooth enough to prevent mechanica~ bonding and allow sliding from the photoformed layer surface. The regions between the ~ilm and the plate that are ~(ot in contact would create channels through which the d~formable-coating-mixture and/or inhibitors could pass to wet and permeate the film. It might be possible to use a porous fused silica plate that would allow, for example, oxygen to pass but not allow photoformable composition to pass and inhibit the interface between the plate and the composition during exposure of a photoformed layer. It would be preferred to improve the optical quality of such a po~ous plate by utilizing a deformable-coating-mixture, ~apable of filling the pores of the plate, such deformable-coating-mixture having substantially the same refractive index as that of fused silica for the radiation in use. Silicone oil compounds such as Laser ~iquids~ ~R. P. Cargille Laboratories, Cedar Grove, NJ) may prove ~seful in this application. Such a porous plate, could be made ~rom, ~or example, silica frit or glass microballs, of good optical quality, that have been sintered together to form the plate shape. It mig~t be preferred to, for example, use a porous fused silica plate with a partially bonded film, such as for example, silicone films, for this method. It would be i3 7 ~

more preferred to use a deformable-coating-mixture with a dissolved inhlbitor/ which provides substantlally the same refractive index as that of the porous fused ~ilica plate, which fills the pores in the plate, thereby improving it's optical clarity for the wavelength in u~e, and which permeates the film, ~hereby forming a permeated-deformable-release-coating on the photoformable compositlon side of the film, and also forms a deformable--composition-release-coating on the photoformed layer upon exposure thereby allowing sliding of the film/plate from the photoformed layer surface.

Figure 3 depicts ~n embodiment utilizing a porous plate 333 with pores filled as described above by a deformable-coating-mixture 310'. Partially adhered to the porous plate 333 is a film 302, having a fir~t surface and a second surface, with the film second surface 302'l positioned to, at least partially, face the photoformable composition 304 and the film first surface 302', at leas~
partially, facing and partially adhered to the porous plate 333. This porous plate 333 with partially adhered ~ilm 302 will hereinafter be referred to as a plate asse~bly. In addition, the film 302 wraps around the edges of porous plate 333 assisting in containing the deformable-~oating-mixture 310'. The deformable-coating-mixture 31~' wets ~nd permeates the film 302 forming a permeated-deformable-release-coating 310. Above the deformable-coating-mixture 310' and porous plate 333 ~s an imaging atmosphere 356, which contains an inhibitor, and which may or may not be the same as the composition atmosphere 352, which is in contact with the photoformable compo~ition 304, at the composition/atmosphere interface 3S3, w~thin a vat 306. The imaging atmosphere 356 may di~fuse into the deformable-coating-mixture 310' forming a dissolved inhibitor 342', which then permeates through film 302 forming a permeated 2 ~ $l~2~3 inhibitor 342. Also, within the vat 306 is a platform 320, which is translated in a direction substantially normal to the film second eurface 302", during the production of photoformed layers 322, by platform translation means 324.
Plate assembly translation means 319 ~shown just as an arm with arrows for the sake of clarity) g:ranslates the plate assembly and deformable-coating-mixture 310' in a direction substantially parallel to the film ~ec:ond surface 302".
Radiation source 314 exposes the photoformable-composition-layer 312 through a photomask 316, the transparent deformable-coatl~g-mixture 310', the film 302, the porous plate 333, and the permeated-deformable-release-coating 310 i~ much the same manner as described in other figures. It would be preferred in the practice of this embodiment, when the deformable coatings are i~ the form of a low vlscosity liquid, that the plate assembly be substantially hori~ontal In operation, the plate assembly would initially be positioned over the platform 320 forming a photoformable-composition-layer 312 between the platform 320 and the permeated-deformable-release-coating 310. Radiation source 314 would then be turned on creating radiation imagewise to pass through photomask 316, the deformable-coating-mixture, the plate assembly, the permeated-deformable-release-coating, and into photoformable-composition-layer 312, thereby creating a ph~toform d l~yer 322 and a deformable-composition-release-coating due to the presence of permeated inhibitor 342. After exposure, the plate assembly would be translated by plate assembly translation means 319, separating the film 302 from the surface of layer 322 and allowing new photoformable co~position 304 to flow i~to ~his region of separation. After the separation is complete, the platform 320 and the photoformed layer 322 are translated a distance of at least one photoformable-~ gj~3 .~6 compcsition-layer 312 from the plate assembly. Next, the plate assembly is positioned above the platform 320 and previous photoformed layer 322 forming a new photoformable-composition-layer 312 between the permeated-deformable-release-coating 310 and the previous photoformed layer 322.
The lmagewise exposure, separation, platform translation and recoating steps would continue as above until a complete three-dimensional object is fabricated.

It is preferred for the product~on of three-dimensional objects that the exposure by radiation be performed imagewise, which lmage xepresents a layer of a three-dimensional object. And it is preferred that the first exposure step, as described above, be adequate to create adhesion between portions of a photoformed layer and a platform, thereby ensuring substantial support for the layer, ensuring substantial subsequent static registration with the imagewise radiation, and ensuring controlled relative position between the previously photoformed layer and the film surface, between which the photoformable-composition-layer would exist. It is further preferred that subsequent exposure steps be adequate to ensure adhesion between portions of the photoformable composition being exposed and portions of the surface of a previously exposed photoformed surface. The presently preferred çxposure method utilizes UV light exposure through or reflected from an appropriate photomask, howeverl other radiative exposure methods, such as, for example, direct writing using a focused scanning laser beam, x-rays, microwave or radio-frequency wave excitation, and the like may be used,assuming such radiation induces photoforming of the photoformable composition. Photomasks useful for the practice of this invention may be silver halide films ~either transmitted through or b~cked by a mirror ~nd reflected through), liquid crystal cells (reflective or ~ ~"3 transmissive), electrostatically deposited powders on a transparent web, ruticons, etc.

It has been found by the Applicants that the use of a focused beam from a relati~ely high power laser as the exposure source yields results that create mor~ adhesion of the photoformed layer to films through which they were exposed when air is the imaging atmosphere. The Appllcants belie~e this is due ~o the polymerization rate outrunning the ~nhibition rate. Use of thinner films, faster lnhibitors, or for example, more concentration o~ oxygen, and/or, for example, oxygen saturated permeated-deformable-release-coatings would be preferred since they would substantially decrease the adhesion of the films to photoformed layers.

Sliding of the film, and more preferably the film, plate and coatings assembly, from the surface o~ a photoformed layer is preferred to reduce the build-up of vacuum forces that might occur during separation of the ~ilm and photoformed layer. Even more preferred, would be sliding the ~ilm, or assembly, to a reyion where there is a substan~ially sharp change in the shape of the film, or assembly, such that the surface of the film is no longer parallel to and moves sharply ~way from the photo~ormed layer surface, allowing the photoformable composition substantially unrestricted ~low into the region where the photoformed layer and film separate. It is prefexred that such a substantial change in ~ilm shape, ~or an assembly, occur at the edge of the plate. And as shown ln Flgure 2, it is most preferred that such film 202 shape chan~e occur as a recess 228 ground into or or~ginally formed in t~e plate 232, which recess 228 is deep enough to allow substantially unrestricted flow of composition 204 into the ~g~27~

region where the film 202 and photoformed layer 222 separate.

Occasionally, during the practice of the preferred lnvention, it may be necessary ~o perform a replenishing step which involves re-saturating the film witA the deformable-coatlng-mixture. Typically during this step, the vacuum pressures which draw the deformable-coating-mixture from between the film and ~he glass are relieved and excess deform~ble-coating-mixture is pumped or allowed to flow into this region. Even more preferable is to first bubble air or pure oxy~en through the deformable-coating-mixture in a separate ~lask, ~hereby re-saturating the deformable-coating-mixture with dissolved inhibitor and then to allowing this (inhibitor saturated) deformable-coating-mixture to re-saturate the film. The Applicants suggest that this re-saturation step may be necessary as often as every ten exposures. However, this depends substantially on, for example, the amount of exposure provided, the area of the layer being ~maged and, for example, the type of photoformable composition in use. In the preferred method as shown in Figure 2, where an exposure and recoating ~f photoformable-composition-layer 212-occur each time the layers pass over a recess, it is even more preferred that the film 202 and plate 232 on each side of the recess region 228 create two separate chambers 250' and 250 so that when one side provides ~he exposure step, the other side is being re-saturated.

Pre-saturating the film prior to assembly allows the system to be used sooner a~d avoids loss of tension in the fllm due to film swelli~g, however this step is not required. It ~s preferred that the deformable-coa~ing-mixture be introduced between the film and the plate a few hours before use to allow the def~rmable-coating-mixture to permeate the film. The Applicants have found that the presence of photoformable composition on the proper side oP
the film substantially speeds the diffusion process and the creation of a permeated-deformable-release-coating. The deformable-coating-mixture need not be placed under pressure to aid the diffusion process, though this is posslble. Typically, the deformable-coating-mixture is introduced into the reglon between the glass and film using ~ust head pressures, however, many kinds of pumps or, ~or example, pressure chamber devices, or for exampl0, bladder pumps may be used. It is pre~erred to draw the deformable coating-mixture from the ~ilm and glass after permeation using vacuum since this causes the film to tightly register with the glass during the imaging s~ep. ~he vacuum is usually created by drawing the air or oxygen from a chamber that contains the deformable-coating-mixture and is connected to the film/glass~deformable-coating-mix~ure assembly. However, any vacuum method~ well known in the art may be used. Since, the deformable-coating-mlxture in the preferred method is FC-40, which has a high specific gravity, even the use of low head pressures may be used to draw the deformable-coating-mixture out. ~hen the deformable-coating-mixture is drawn out between the film and the glass, there is still a substantial amount of deformable-coating-mixture left between the two. This is due to viscosity and flow resistance effects that compete with the drawing out v~cuum.

After the exposure step~ sliding o~ the assembly, parallel to the second film surface and relative to the previously formed layers, can be performed pr~or to translation of the platform and layers one or more layer thickness away from the plate. It is preferred, however, to flrst translate the platform and pre~iously formed layers away one layer thickness prior to sliding of the assemblyO

2~ 2~

It may be possible to translate the platform away from the plate more than one layer thickness and then move the platform back to a one layer thickness position during each layer formation step, but this is not preferred. If a roughened plate or a porous fused silica plate, with a partially adhered film is used, however, it is preferred that the sliding translation occur pr:ior to platform translation.

The special materials of construction usually chosen as shown in Figure 2 that have not been described heretofore are listed as follows. This in no way should be percei~ed as a limitation of possible materials that could be used rather the information is being provided to aid others o~
ordinary skill in the art to construct such an assembly:

Tube Screen- Aluminum, steel or copper screen, with sharp points removed or turned inward, which has been rolled to the proper diameter and sewn, soldered,or brazed at the seam.

Flexible Tubing- Tygon~ Tubin~ (VRW Scientific, San Franci.~co CA) Translation Means- Unidex Xl motor controller, ATS-206-HM-6" Travel Positioning Motor Driven Stage W/Stepper Motor and Xome Marker,(Aerotech, Pitts. PA).

Claims (29)

What is claimed is:

1. A method for fabricating an integral three-dimensional object from successive layer of a photoformable composition comprising the steps of:
a) positioning a substantially transparent, composition-impermeable, composition-inert, semi-permeable film, having a first surface and a second surface, such that said first surface is, at least partially, in contact with an imaging atmosphere, and said second surface is at least partially, in contact with the photoformable composition;
b) contacting an interface of said composition with a composition atmosphere;
c) allowing said imaging atmosphere to permeate through said film and partially into a photoformable-composition-layer;
d) exposing said photoformable-composition-layer to radiation imagewise through said film making a photoformed layer and a deformable-composition-release-coating;
e) sliding said film from said photoformed layer;
f) positioning said film in such a way as to form a photoformable-composition-layer between said previously made photoformed layer and said film second surface; and g) repeating steps c-f until said layers of the integral three dimensional object are formed.

2. A method for fabricating an integral three-dimensional object as recited in Claim 1 wherein said film has molecular weight cutoff pores and said film does not substantially wet said composition

3. A method for fabricating an integral three-dimensional object as recited in Claim 1 wherein said film has expandable pores and said film does not substantially wet said composition.

4. A method for fabricating an integral three-dimensional object as recited in Claim 1 wherein said film is elastomeric and does not substantially wet said composition.

5. A method for fabricating an integral three-dimensional object as recited in Claim 4 wherein said film is a fluoroelastomer.

6. A method for fabricating an integral three-dimensional object as recited in Claim 1 wherein both said imaging atmosphere and said composition atmosphere are air.

7. A method for fabricating an integral three-dimensional object as recited in Claim 1 wherein said imaging atmosphere comprises oxygen in a concentration higher than that normally found in air.

8. A method for fabricating an integral three-dimensional object as recited in Claim 1 wherein said composition atmosphere comprises an inert gas in a concentration higher than that normally found in air.

9. A method for fabricating an integral three-dimensional object from successive layers of a photoformable composition comprising the steps of:

a) positioning a substantially transparent, composition-inert, composition-impermeable, semi-permeable film, having a first surface and a second surface, with said second surface at least partially in contact with the photoformable composition in a vat;

b) holding said film to a substantially flat shape with a tenter frame having an edge;

c) contacting said film first surface at least partially, with an imaging atmosphere;

d) contacting an interface of said composition with a composition atmosphere;

e) forming a photoformable-composition-layer between a platform and said film second surface;

f) allowing said imaging atmosphere to permeate through said film and partially into said photoformable-composition-layer;

g) exposing said photoformable-composition-layer to radiation imagewise through said film, thus making a deformable-composition release-coating and a photoformed layer that is substantially adhered to said platform, or to a previously photoformed layer;

h) sliding said tenter frame and film relative to said photoformed layer past said edge of said tenter frame;

i) positioning said tenter frame and film forming a photoformable-composition-layer between said film and said previously photoformed layer; and j) repeating steps g-i until said layers of the integral three-dimensional object are formed.

10. A method for fabricating an integral three-dimensional object from successive layers of a photoformable composition comprising the steps of:

a) positioning a substantially transparent, composition-inert, composition-impermeable, semi-permeable film, having a first surface and a second surface, with said second surface at least partially in contact with the photoformable composition in a vat;

b) holding said film to a substantially flat shape with a tenter frame having an edge;

c) contacting said film first surface, at least partially, with a deformable-coating-mixture which in turn is in contact with an imaging atmosphere capable of dissolving in said deformable-coating-mixture;

d) contacting an interface of said photoformable composition with a composition atmosphere;

e) allowing said deformable-coating-mixture and said dissolved imaging atmosphere to permeate through said film forming a permeated-deformable-release-coating between said film and said composition, f) forming a photoformable-composition-layer between said permeated-deformable-release-coating and a translatable platform;

g) exposing said photoformable-composition-layer to radiation imagewise through said film, deformable-coating-mixture, and permeated-deformable-release-coating creating a deformable-composition-release-csating and a photoformed layer that is substantially adhered to said platform, or to a previously photoformed layer;

h) sliding said tenter frame, film, and deformable-coating-mixture relative to said photoformed layer past said edge of said tenter frame;

i) positioning said tenter frame, film, deformable coating mixture, and permeated deformable release coating such that a photoformable-composition-layer is created between said permeated-deformable-release-coating and said previous photoformed layer; and j) repeating steps g-i until said layers of the integral three-dimensional object are formed.

11. A method for fabricating an integral three-dimensional object from successive layers of a photoformable composition comprising the steps of:

a) positioning a substantially transparent, composition-inert, composition-impermeable, semi-permeable film, having a first surface and a second surface, with said second surface at least partially in contact with the photoformable composition in a vat;

b) securing said film against a transparent plate, having an edge, in a frame;

c) introducing a deformable-coating-mixture between said plate and said film;

d) contacting an interface of said photoformable composition with a composition atmosphere;

e) allowing said deformable-coating-mixture to permeate through said film forming a permeated-deformable-release-coating between said film and said composition;

f) drawing said deformable-coating-mixture from between said film and said plate such that said film substantially conforms to said plate surface;

g) forming a photoformable-composition-layer between a translatable platform and said permeated-deformable-release-coating;

h) exposing said photoformable-composition-layer to radiation imagewise through said plate, deformable-coating-mixture, film, and permeated deformable release coating such that portions of a photoformed layer are substantially adhered to said platform, or a previously photoformed layer;

i) sliding said frame, plate, film, and deformable coating mixture relative to said photoformed layer past said edge of said plate while replenishing said deformable-coating-mixture between said film and said plate;

j) drawing said deformable-coating-mixture from between said film and said plate such that said film substantially conforms to said plate surface;

k) positioning said frame, plate, film, deformable-coating-mixture, and permeated-deformable-release-coating such that a photoformable-composition-layer is formed between said permeated-deformable-release-coating and said previous photoformed layer; and l) repeating steps h-k until said layers of the integral three-dimensional object are fabricated.

12. A method for fabricating an integral three-dimensional object from successive thill layers of a photoformable composition comprising the steps of:

a) positioning a substantially inert, transparent, and composition-impermeable, semi-permeable film, having a first surface and a second surface, such that said first surface is partially adhered to a surface of a porous plate, having an edge, and said second surface is, at least partially, in contact with the photoformable composition;

b) filling the pores of said porous plate with a deformable-coating-mixture and wetting said film first surface with said deformable-coating-mixture;

c) allowing said deformable-coating-mixture to permeate through said film forming a permeated-deformable-release-coating between said film and said photoformable composition;

d) forming a photoformable-composition-layer between said permeated deformable release coating and a translatable platform;

e) exposing said photoformable-composition-layer to radiation imagewise through said porous plate, film, deformable-coating-mixture and permeated-deformable-release-coating such that portions of a photoformed layer are substantially adhered to said platform, or previously photoformed layer;

f) sliding said porous plate, film, and deformable-coating-mixture relative to said photoformed layer past said edge of said plate;

g) positioning said porous plate, film, deformable-coating-mixture, and permeated-deformable-release-coating making a photoformable-composition-layer between said permeated-deformable-release-coating and said previous photoformed layer; and h) repeating steps e-g until said layers of the integral three-dimensional object are fabricated.

13. An apparatus comprising:

a) a substantially transparent, composition-inert, composition-impermeable, semi-permeable film, having a first surface and a second surface, said first surface being adaptable to partially contact an imaging atmosphere capable of permeating said film, and said second surface being adaptable to partially contact a photoformable composition;

b) means for creating imagewise radiation through said film in order to form a photoformed layer and a deformable-composition-release-coating at said film second surface; and c) means for separating said film from said photoformed layer.

14. An apparatus as recited in Claim 13 wherein said film is of substantially different molecular polarity than that of said composition.

15. An apparatus as recited in Claim 13 wherein said film is a fluoroelastomer film.

16. An apparatus as recited in Claim 13 wherein said imaging atmosphere comprises air.

17. An apparatus as recited in Claim 13 wherein said imaging atmosphere comprises oxygen in a greater concentration than normally found in air.

18. An apparatus as recited in Claim 13 further comprising:

d) means for forming additional layers of photoformable composition on previous photoformed layers.

19. An apparatus as recited in Claim 18 further comprising:

e) a tenter frame for holding said film to a shape;

f) frame assembly translation means for translating said tenter frame and film slidably;

g) a platform being adaptable to adhere to said photoformed layers; and h) platform translation means for moving said platform.

20. An apparatus as recited in Claim 19 wherein said film is adapted to be permeated by a deformable-coating-mixture and dissolved inhibitors.

21. An apparatus comprising:

a) a substantially transparent, composition-inert, composition-impermeable, semi-permeable film, having a first surface and a second surface, said second surface being adaptable to partially contact a photoformable composition;

b) means for creating imagewise radiation through said film in order to form a photoformed layer and a deformable-composition-release-coating at said film second surface;

c) a platform being adaptable to adhere to said photoformed layer;

d) platform translation means for moving said platform.

e) a transparent plate holding said film to a shape, and a frame and a flange for securing said film against said plate in order to form a chamber adapted to hold deformable-coating-mixture and dissolved inhibitors between said plate and said film; and f) frame assembly translation means for translating said frame, plate, flange, and film slidably allowing separation of said film from said photoformed layers and application of photoformable-composition-layers.

22. An apparatus as recited in claim 21 further comprising:

g) a recess region in said plate;

h) a wedge separating said chamber into a first chamber and a second chamber, said wedge being configured to allow flow of photoformable composition through said recess region;

i) pumping means for drawing deformable-coating-mixture out of said first chamber while introducing deformable-coating-mixture into said second chamber and vice-versa; and j) replenishment means for replacing dissolved inhibitor and permeated inhibitor.

23. An apparatus as recited in Claim 22 wherein said film is a fluoroelastomer film.

24. An apparatus as recited in Claim 22 wherein said dissolved inhibitor comprises air.

25. An apparatus as recited in Claim 22 wherein said dissolved inhibitor comprises oxygen in a greater concentration than normally found in air.

26. An apparatus as recited in claim 22 wherein said deformable-coating-mixture is a perfluorocarbon liquid.

27. An apparatus comprising:

a) a transparent porous plate, having pores, wherein said pores are adapted to be filled with a deformable-coating-mixture having similar retractive index to that of said porous plate;

b) a substantially transparent, composition-inert, composition-impermeable, semi-permeable film, having a first surface and a second surface, said first surface being partially adhered to said plate and wetted by said deformable-coating-mixture, said second second being adapted to partially contact a photoformable composition, and said film being adapted to permeate said deformable-coating-mixture and a dissolved imaging atmosphere;

c) means for creating imagewise radiation through said porous plate, deformable-coating-mixture, and film in order to form a photoformed layer and a deformable-composition-release-coating at said film second surface;

d) plate assembly translation means for moving said porous plate, film, and deformable-coating-mixture in a direction substantially parallel to said film second surface;

e) a platform being adaptable to adhere to said photoformed layers; and f) platform translation means for moving said platform.

28. A three-dimensional object formation apparatus as recited in Claim 27 wherein said film is a silicone film and said deformable-coating-mixture is a silicone oil.

29. A three-dimensional object formation apparatus as recited in Claim 27 wherein said film is a theromplastic fluoroelastomer film and said deformable-coating-mixture is a perfluorocarbon liquid.