CA2211023A1

CA2211023A1 - Method of deblocking, extracting and cleaning polymeric articles with supercritical fluid

Info

Publication number: CA2211023A1
Application number: CA002211023A
Authority: CA
Inventors: Wilson Leonard Terry Jr.; Roger James Hoffman
Original assignee: Individual
Current assignee: Novartis AG
Priority date: 1995-02-22
Filing date: 1996-02-09
Publication date: 1996-08-29
Also published as: AU4623296A; MX9706417A; FI973381A0; EP0809564A1; US5607518A; DE69602427T2; DE69602427D1; EP0809564B1; ATE179924T1; HUP9702450A2; NO973809L; CN1175921A; NO973809D0; PL321941A1; BR9607340A; IL117143A0; ZA961365B; WO1996026059A1; JPH11500078A; KR19980702373A

Abstract

Methods of deblocking a polymeric article from a mold and/or removing undesirable materials from a polymeric article by applying supercritical fluids to the polymeric article are disclosed. A preferred process is the treatment of ophthalmic lenses, such as contact lenses (16). Supercritical fluid, composed primarily of carbon dioxide, is applied to a contact lens (16) affixed to a mold (18) subsequent to the polymerization step. The application of supercritical fluid (SCF) causes the lens to efficiently and consistently separate from the mold, removes undesirable materials such as unreacted monomer oligomers, or residual solvents from the lens core, and/or cleans the lens surface of adhered debris.

Description

WO 96/26059 PCTnEP9610~554 ~DSrHOD OP n~RT~ JC E~nR~C~ING AlnD CLB~NING POLY~ERIC ~RIIClES ~nrH

BACKGROUND OF THE INVENTION

1. FIELD OF THE INVENTION

This invention relates broadly to eAL,dcLion and cleaning of polymeric articles and mold sepa,dUon processes More specirically, this invention relates to molded-lens e~L,a- lion, cleaning and ~klc rL~i'l9 processes .

2. DESCRIPTION OF THE RELATED ART

The use of supercritical fluids (SCF) for ~ ;. .g and e~ ~cLI Ig in the food industry is well known (See Chem. En~r. Intemat. Ed., vol. 100, no. 3, p. 11~9). Forexample, U.S. Patent No. 3,806,619, issued Apr. 23, 1974 to Zosel, describes a p,ucess for decarrei"aLing coffee with su~,er~iLcal fluids. Sul,er~ilical fluids have also been used to dry porous mdL~,;als pr~pa~:d in sol-gel p,ucesses Supe,c,ili- al fluid eA~clclioo of hy- ,upl~Li~ polymers, such as polypropylene, has also been explored (See J. APPI. Polvm. Sci.. 48, no. 9, 615193, p.
1607-9). Fu,U,e""or~, porous spor,ges of biodeg,adable polymers have been formed by a,oply;. ,9 supercritical fluids in a ",anoer requiring a sharp pressure drop (See PCT Int. Appl.
No. WO 9109079, De Ponti). However, the erri~enl use of su,uer ,ilical fluids requires high t~r,.per~t.lres and pressures, which may da",age certain polymeric r ,alen /ls.

Numerous polymeric articles are formed by placing a n,onor"elic solution into a mold and then i"itiaL"9 pol~",e,i~aLGn. The efficient removal of molded articles from the mold ,~,urt:se, IL j a critical step in the design of a manufacturing prucess. After the polymeric article is sepa~aled from the mold, the article must typically be subjected to eAL,aclion prucesses to remove undesirable n~dk~ Is, such as Ul " t:acled or pa(Li~lly reacted ",ono",er:. (i.e. oligomers or short chain polymers) and residual solvent. An ophU~alm;c lens is an e,~",ple of a polymeric article which may be molded in such a manner.
Ophthalmic lenses such as conLact lenses are typically fomled from hydrophilic mono",er~
in order to enhance biocom,c ~ y v~/ith the eye. Contact lenses formed from hydrophilic polymers are desirable in part because hydrophilic contact lenses move well on the eye.

W 096/26059 PCTAEP~G/00554 This movement enhances tear flow and debris removal beneath the lens, thereby improving patient co",roll.

One method of forming a contact lens involves lathing the lens from a plerol",ed polymeric disc, a so-called lens "button". Another method of forming contact lenses, as previously-",enlioned, involves placing a monomeric solution into a lens mold and polymerizing the r"ono"~er. Double-sided molding is an example of the second type of lens molding process which has been gaining in popularity in recent times.

In molding lenses, subsequent to polymerization, the lenses are typically "deblocked", i.e., separated from the mold, and s~ Ihj~cted to exl,d~lion pr-,cesses for a period of hours. The extraction processes remove unreacted monomer and partially-reacted oligomer, solvents or other undesirable materials. These commercial extraction processes typically involve conla~;ling the lenses with oryall.., solvents, such as isopropyl alcohol, to solvate the undesireables. Such wet extraction processes are time consuming and costly, produce a wet lens which is not suited to immediate surface treatment. Furthermore, these ekl, d~;iion processes yield an effluent stream of solvent and l"ono",er which is not easily disposed of.

In addition, the step of deblocking the lens presents manufacturing problems. First, the deblocki,lg must occur quickly and consislently, in order to ",d,~i",i~e production erri.,;2n~y.
Second, the detlo,cki"g must be co""~lete, i e., even minor po,lions of the polymeric lens must not remain adhered to the mold. Incol"rle' blocking typically results in suL,aldnlial volumes of production scrap because the lens is likely to tear when removed from the mold.
Moreover, even slight lens surface imperfections, caused by the lens adhering to the mold during deblocking, ll dnslale into major visual d;~lol lions for the lens wearer.

Thus, there is a need for improvements in erricien~;y, safety, cost, and waste-mini",i~dlion in polymeric-article (especially ophthalmic-device) e,~l,d~,lion and cleaning processes. In adcli~iorl, there is a need for an improved method of deL'ocking a polymeric article (especially an ophthalmic device) from a mold immediately s~ ~hsequent to poly" ,el i~alion.

SUMMARY OF THE INVENTION

An object of the invention is to provide a method of e~l,dcling undesirable materials from a polymeric article and/or cleaning from the surface of a polymeric article any undesirable Illalel;als which have adhered to the surface without introducing excessive organic solvents.

W 096r26059 PCT~~S~1~0554 Another object of the invention is to provide a method of quickly and efficiently deblochi"g a polymeric article from a mold subsequent to fo""aLion of the polymeric article by polymerization in the mold.

A further object of the invention is to provide a method for simultaneously removing undesirable l"al~,ials from a polymeric article and deblocking a polymeric article from a mold.

Yet another object of this invention is to reduce production time required to prucess polymeric articles.

An adcliLional object of the invention is to reduce prod~l- tion scrap in the production of polymeric articles.

Even another object of this invention is to reduce the amount of organic solvents required to produce polymeric a, ~ s One embodiment of the invention is a method of removing ulldeail ~ e ",ale,ials from hydrophilic polymeric articles. The method involves cor)Lacli"g the polymeric article with a su,~,er.;, ilical fluid at condilions and for a time sufficient to remove L",desi, e materials from the polymeric article. The removal may involve e~L,actio,n of undesirable malé,ials from the polymeric core or cleaning of undesi, -le ",~le,;al-~ from the surface of the polymer. In a plerelled embodiment, ophthalmic lenses are ~"la~led with super~rilical fluid especially supêr~, itical fluids containing carbon dioxide to remove monolllêra ~o' ~..,era and/orsolvents remaining from the preceding lens-poly",eri~alion pr~cess.

Another e",bo.li",enl is a method of deblocking polymeric articles from molds sl ~hseq~ ~ent to poly",e~i~dLion prucesses. The method includes the step of conld- li"g the polymeric article with a su~,er~ilical fluid at conclitiûr~s and for a time sufficient to sepa,dle the polymeric article from the mold. A prerelled embodiment is a method of debl~~-king ophthalmic lenses from molds suhsequent to the lens-poly"~eli~alion p,ucess by conla~;Li"g the lens with a supêr~, ilical fluid pr~rerdbly one which includes carbon dioxide.

In yet anvLl ,er embodiment a method of simultaneously removing undesirable l"alerials from a polymeric article and deklockirlg a polymeric article from a mold is ~isrlose-l The method includes a step of cGnla~;ling the polymeric article with supercritical fluid at conditions and for a time sufficient to both remove certain undesirable materials from the polymeric article and separate the polymeric article from the mold.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side sectional view of a mullicG"~ponent batch-process super~;,ilical-fluid treatment apparatus.

FIG. 2 is a side sectional view of an in-line super~;,ilical-fluid treatment appa,dlus.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present innovative "~elhods of e~ a~ Ig undesirable materials from a polymeric article deblocking a polymeric article from a mold and/or cleaning undesirable materials from the surface of a polymeric article involve the steps of:
(1) providing a stream of supelc,ilical fluid at a predele",lined temperature and pressure;
(2) conld~i, ,9 a polymeric article with the superc, ilical (or near-supercritical) fluid for a predetermined period of time;
(3) ayildling the supercritical fluid in a ",anner such that at least one of the follov~ing occur (a) the polymeric article is sepd,dled (d bl~ ed) from the mold (b) unreacted ",onor"er oligomer and/or solvent is e~l,d~d from the polymeric article with thesuper~;,ilical fluid andtor (c) undesirable Illdl~l;91s are removed from the surface of the polymeric article; and (4) removing the s- ,uer~;~ilical fluid which may include un~a~led ",ono"~er 1o' 3. n,er and/or solvent from the polymeric article and mold.

A "supercritical fluid" as the term is used herein means a substance at a temperature and pressure which places the subsldnce in or near the super~, ilicdl regime. A temperature of at least about 20~C and a pressure at least about 600 psia are b~l aved to be sufficient to achieve the advar,lages of the present invention.

"Removing u"desi,dble ",dle~ials" as used herein means eitherextracting undesirable Illaleli ~Is from the polymeric core or cleaning undesirable "~alerials from the surface of the polymeric article. Undesi- t: le materials which may be e~cled include ",ono",er:, partially-reacted oligo~."era solvents poly"~eri~alion ir,itidlor~ andthe like. Undesirable WO 961260~i9 PCT/EP96/00554 ",dle,ials which may be cleaned from the surface of the polymeric article include the aforementioned-undesirable ",dlerials debris or surface col,ld"lil~anL~ such as abrasives used in surface polishing processes oils and the like The advantages achieved by the pr~tice of the present invention are numerous. First polymeric articles which are treated with superc,ilical fluids (SCF) are essenlidlly "dry" i.e.
free of solvent after SCF treatment, while oryanic solvent exll aCIiOn, cleaning or deblocking processes yield "wet" products i.e. some solvent remains in or on the article. In order to further process a polymeric article which is "wet" the article must be dried over a period of time, and typically at an elevated temperature. In co"ll~L polymeric articles which have been subjected to SCF l~ealmenl may be nearly ill~l.led,ately indexed or moved to the next processing step (e.g. a sl ~hsequent surface treatment process).

Another advantage of the present invention is that the use of rla" "~able potentially toxic orgal1ic solvents is minimized or eliminated. Thus, the invention increases safety in the manufacturing environment and/or reduces costs ~-sso~i~led with proleclillg workers from the ha~ar~s of oryanic solvents. On a similar note the expenses and ha,an~s ~ssoc ~IAd with .I;SPOSAI of spent organic solvents is reduced or eli.l,;,-al~d with the present invention.

The instant invention offers yet anGtl ,er advantage in improving e~l, aclion err..;enc~.
d~lion of contact lenses with suue,.;lilical fluids in a~Grdance with the instant teachings may yield n,ono",er/a'igQ."er concer,l,dliGrls less than about 2 weight percent in a 1.5 to 3 hour time period using a 95 weight per~enl isopr~pyl alcohol / 5 weight per~r.L carbon dioxide SCF mixture at about a one gallon per minute flow rate. In cor,~asl exl,dclion of co"l~i lenses with solvent typically yields r"onol"er/~o' go "er conce, Ill dlions at about 2% in a 24 hour time period. Thus the pr~senL SCF e,~clion prucess yields the same quality product in a greatly reduced time frame.

While the amount of ~"~leacled ",onGr.,ertaligo "er remaining in the finished polymeric article which can be tolerated depends on the intended ~ rr' -~ion of the polymeric article the spe.iir,calions for medical devices ophthalmic lenses and the like are typically quite sl,i"genl. Thus the prt:senl invention is particularly suited to arpli~lion in those areas which have res~ /e reg~ t~ry requil~menls especially in the ophthalmic lens industry.

Polymeric articles which may be treated with superc;, itical fluids in accorcla"ce with the present invention include a wide variety of polymeric articles which are formed by initiating W 096/26059 PCT~EP9''~554 polymerization of a monomeric mixture in a mold. Exampl~s of such polymeric articles include without l;milalion thereto medical devices and components such as drug delivery devices (transdermal ophll,dl",ic parenteral etc.) and components thereof; and in particular ophLlla!,l,ic devices including vision correction devices such as contact lenses ocular i",plar,la ocular onlays and co",po"ents thereof.

Polymers suited to the formation of polymeric articles which may be advant~geo~lsly subjected to the presently described inventive processes include without li",ilalion thereto, hyd,uphobic polymers such as polyethylene polypropylene poly(vinyl py"M ~-ne) orpolysiloxanes; hydrophilic polymers such as poly(2-hydroxyethyl methacrylate) and poly(vinyl alcohol); biodegradable polymers such as polylactides polyglycolides and the like; and anLi",;c,c bial polymers such as polyquale",aly a",r"onium compounds.
Preferably the SCF treatment processes of the prt:sel,L invention are applied to hydluph;l;c polymeric articles capable of forming hydrogels when equilibrated with water (i.e. capable of absoi L ng about 10 weight percent water or more).

The SCF treatment processes of the present invention are preferably applied to contact lenses which are the copoly",el i~dLiol1 product of a copolymerizable mac(on,er and two or more copoly" ,el i~able " ,ono" ,ers.

The copoly",e,i~atlc macromer is advantageously a macromer comprising a polysiloxane segment even more prt:fe"~d a polydimeLl,yls ~x~ne segment. Said ",ac,ur"er alsopr~fen~d compnses in addilion urethane linkages and two or up to five terminal vinylic groups which are sl ~ - le for a polymel i~alion ,t:a~ lion with the copolymerizable monomers.
A most prerel,~d ",ac,umer COI"pl ises a polydimethy;;; ~ ~ne segment to which a vinylic isocyanate is bonded such as isocyal,dloell,yl\"~Ll,aclylate (IEM). The ",a~ ,u",ermay co",plise other seylllenls not yet r"enlio,-ed specifically. Exdlll~ lcs for such segments are perfluorupolyether segments diisocyanates or derivatives of gluconic acid.

The first type of copolymerizable ",onor"er used jointly with said ",acr~l"er is a monovinyllc siloxane having up to 15 silicon atoms A preferred e,~d",rle is 3-tris(trimethylsiloxy)silyl-propyl mell,dclylate (TRIS) The second type of copolymerizable monomer used jointly with said n,ac,un,er is a hydrophilic copolymerizable ",onol"er as usually used in the manufacture of contact lenses Typical exd" ~ les are hydroxy-C2-C4-alkyl (meth)acrylates such as 2-hydroxyethyl WO 96/26059 PCT~P96~00554 ",ell ,;ac~late (meth)acrylic acid dimethylacrylamide or N-vinyl py"uli~one of which dimethylacrylamide (DMA) is es,vecidlly preferr~d.

In view of the foregoing it is preferred to apply the p,ucess of the present invention to a polymeric article which is a collld~ I lens obtained form a mixture of a copolymerizable ,,,ac,umer and two or more prefer~bly two copol~"~,e,i~able ",Gno",ers as defined hereinbefore.

The mixture of ",ac~n,er ",ono,ner of the first type and ",onG",er of the second type typically co" ",, iaes, in pe~ue, ll by weight, ,,,ac,ulller: about 30 to 60 %
n,onomer of the first type: about 12.5 to 35 %, ",or,or"er of the second type: about 27.5 to 35 %.

More pr~re" ~d the mixture co" "~, ises in percent by weight:
",ac, u,"el . about 33 to 56 %
mollor"er of the first type: about 14 to 33 %
",ono",er of the second type: about 30 to 33 %.

Three examples of very pr~re~ d mixtures cûroplise about:
50 % of ".ac,o",er 20 % of ",onGl"er of the first type and 30 % of the second type;
56 % of ",ac~v",er 14 % of monGmer of the first type and 30 % of the second type;
33 % of "~ac,umer 33 % of ",onor"er of the first type and 33 % of the second type;

In these mixtures, the ."onû",er of the first type is most pr~:ferdbly TRIS and the ",onor"er of the second type is most prererdbly DMA. Very much p~ere"ed are the mixtures ~ osed in the examples or aF~ -Qtion of the I;c~ ~osecl processes to contact lenses made from said mixtures respectively.

~ Furthemmore by apply;ng the super~, ilical fluid immer - ?Oysl Ihsec1~ ~ent to suL,alanlial completion of the pol~llleli~dlion ~I:a~ lion i.e. while the polymeric article is still in the mold ~ one obtains a rer.,a,kable advantage in debl~ ing the article from the mold. Thus appO ~ Qtion of SCF's at a time imme ~ Iy s~ ~hsequent to polymerization cGmr st;o.) can simultaneously d~blo~ the article from the mold and extract undesirable u, ll~acLed mol)GIllera~ partially-rea~.led ~ .llela solvents or other additives. This r~r"a,l~able dlscovery provides the arort:",enlioned advanlages regarding solvent recluction or elimination, while simultaneously eliminating the need for additional equipment omlldLelials to separate the polymeric article from the mold.

In the production of contact lenses, the present invention displays particularly remarkable advantages. Contact lenses which are molded in a do~ ~hlQ s ided molding process are typically molded in a hydrophobic polymer mold. A r"onon)eric mixture, which co,r""only includes 2-hydroxyethyl methacrylate for hydrophilic "soft" contact lenses, is introduced into the mold. The mold containing the ",ono",er may be i, I~ Pd to initiate polymel i~dUon.
Once the lens has been formed, i.e., poly",e,i~dion is suLsla"Lially cor"r'ete, the lens must be removed, i.e., deblocked, from the mold. At times, lenses are scrapped because of damage caused during debl~ :king steps, since the adhesion of the lens to the mold impairs the deblocking prucess. In addition, unreacted monomer and o';gon,ers are undesirable Illdlerials which must be removed from the lens. Removal of undesirable r"ala~ials may involve numerous suhsequent processing steps, including solvent exl,dclion and heat treating over extended time periods. Thus, many c~r"",er ,ial contact lens production processes include numerous processing steps relating to e~ acLion and Ide~'Dd~i"9.

However, in accor~lanc;e with one embodiment of the present invention, a simultaneous e,cL, duLion and deL ' ~ ~ ki"g step may be sl Ihstit~ ~tecl for the prior art sequential exL, d~Lion an~d c; l~ ing steps. It has been un~Ypect~ y found that the apFli ~ -tion of super~;, iLical fluid to a contact lens in a mold for e~l(acUon purposes causes the lens to detach from the molcl.
This reduction in the attractive forces b~ /ccn the lens and the mold enables a quick removal of the lens from the mold, while minimizing the likelihood of lens damage and conc~",ilanl scrap ro""ation.

The superc,itical sul-alance may be selected from a wide variety of suL,:.Ldnces which are gases or liquids at room temperature and pressure, induding without limitation thereto, carbon dioxide; water; alcohols, especially low ",~'ec~ weight r'~ ~hols such as isoprupyl alcohol and ethanol; a"""ollia, ethylene; carbon disulfide; sulfurhexafluoride; hexane;
acetone; and other col"",on o,yanic solvents, and mixtures thereof. A prerelled group of SCF's includes alcohols such as isopr()pyl alcohol and relatively inert, inoccuous gases or fluids such as carbon dioxide or water. Carbon dioxide and isop~upyl alcohol are more t prere, led.

While the con-litions of the sul,sla"ce used as the s~")er-;,ilic,dl fluid may vary somewhat, the substance must be at a temperature and pressure which places the suL.slance in or WO 96126059 PCT~P96~00554 near the super~, ilical region. The temperature and pressure of the super.;,ilical fluid depend on the chosen fluid comrosition. For carbon dioxide, the temperature and pressure for producing a super.;,ilical fluid are above about 1085 psi and about 31~C. A temperature range of 21 to 45~C and pressure range of 600 to 5000 psia are believed useful for a carbon dioxide stream. Pler~r~bly, the carbon dioxide stream is ~ ;nlail ~ed at a temperature of about 21 to 35~C and a pressure of about 900 to 3000 psia.

Particularly pr~:re, I~:d mixtures of fluids useful in exl,dcli"g and deblocking contact lenses include carbon dioxide and isoprupyl alcohol (IPA). A pr~rei,ed cGr"posilion of the fluid includes about 70 to about 99 weight percent carbon dioxide and about 1 to about 30 weight percent isoprupyl alcohol. A more pl~:rell~:d fluid c~",posilion includes about 75 to about 85 weight percent carbon dioxide and about 15 to about 25 weight percent isopropyl alcohol.

In order to pr~pe, Iy extract undesirable IlldLel; ~Is from a contact lens within a lens mold, the super~,ilical fluid should be properly agitate~i Sufficient s~gil~lioh of the super~,ilical fluid may occur by merely cûnlac~ g a stream of supel~,,ilical fluid with the polymeric article to be treated. However, a prefe, ~t:d flow regime is in the turbulent range, i.e., fluid flows having Reynold's numbers above 2100.

Su~el~lilicdl fluid extld.,lio,- equipment may be procured cor",))er~ially from a variety of sources, including Pressure Products Industries, Inc. (Warminster, Pennsylvania) and Autoclave Engineering (Erie, Pennsylvania). A pr~rel It:d SCF extractor for opthalmic devices, such as conlacl lenses, is the EP Model 12-30ûO, available from Autoclave Engineering.

In a pr~re"t:d embodiment, the invention is a method for l,e~ling an ophthldll :c lens suhsequent to the poly",e~i~alion of the lens. This embodiment of the invention is ~lisçl~ssed with ,kspec~ to a particularly prerel,~d embodiment - the treatment of a contact lens. However, this embodiment of the invention is not limited to contact lenses, but includes intraocular lenses, drug delivery lenses, comeal onlays, etc.
t If the lens is ~ablicdled by a double sided molding prucess, one half of the mold is separdled from the lens priorto a~t ~ on of super~,ilicdl fluid. Typically, the lens r~ma;ns removably affixed to the base mold half (convex mold half), leaving the front or convex lens surface exposed. The lens mold may be treated in order to render one mold half more CA 022ll023 l997-07-2l adherent and/or the other mold half less adherent, in order to ensure consistent location of the lens on the desired mold half. Altematively, sensing equipment may be used to determine the mold half to which the lens is removably-affixed, so that the lens-conLai"ing mold half is treated with the supercritical fluid. Regardless of the lecl " ,.., Ie chosen, the lens-retaining mold half is treated with supercritical fluid s~ ~hsequent to the first mold half separation step.

Treatment of the lens on the mold half with superc, ilic al fluid is prerendbly acccjr"plisl ,ed in a batch prucess to ensure thorough contact with the fluid and to ensure the fluid remains or cycles through the supercritical temperature and pressure ranges. In order to increase processing efficiencies, a plurality of lenses may be treated in one batch p, uc,ess. FIG. 1 sche",dlically illustrates an appdral-ls c~p~h'~ of batch treating a plurality of lenses.

Referring to FIG. 1, lens-treating appardlus 10 is surrounded with ins~ l'qtion 12 sufficient to mainldil, the applied fluid at the desired supercritical temperature and pressure ranges.
Trays 14 support a plurality of lenses 16 affixed to molds 18. The support trays either havle pe, rc,rdlions or are surri~;;ar,lly porous to allow super.;, ilical fluid to flow through the trays.

In operation, the trays are loaded into lens treating appar~l.Js 10, either manually or via an a~ ,l"dled lens distribution system, through an access opening (not shown), with the access opening being sealed s~ ~hsequent to the loading step. Super~;,ilical fluid, enl~,i"g through inlet Z0 at a rate of about 0.1 to 5 gallons per minute, is distributed u, lirulll,ly to p~ss~geways poailioned along the walls of the c,onldi"er by agi'~ion means 22. At a point near the top of appa, dlus 10, super~,, iLical fluid passes through a flow distribution member 24, which provides uniform supercrilic,al fluid flow across a cross-section of the appar~lus perpendicular to the flow. The superc;liLicdl fluid flows through trays 14, c~jnla.;ling lenses 16 and molds 18, prerer~bly in a turbulent fashion, before exiting through the fluid outlet (not shown).

An all~,l,aLi~/e lens treating appa,dL.Is 40 is illustrated in FIG. 2. Apparatus 40, shown in closed configuation, includes inlet 42 on upper portion 44 and outlet 46 on lower portion 48.
Apparatus 40 further includes ~ l, lion means 50 and peripheral sealing means 52. The sealing of upper portion 44 to lower portion 48, via peripheral sealing means 52, defines lens treating cavity 60.

W096/26059 PCTAEP96/00~54 In operation, upper and lower portions 44 and 48 are vertically sepa,dled to allow lens 54 affixed to mold 56 to index on conveyor 58 to a position between the upper and lower portions. After a lens-conlaiui"g mold is indexed to the desired posiliot1 intermediate upper and lower portions 44 and 48, the upper and lower po, lions are mated, thereby fo" ";. ,9 a liquid impemmeable seal defined by peripheral sealing means ~2. Super~,ilical fluid flows through inlet 42 and is dispersed by agitating means 50, thereby conla~,ling the lens in a turbulent fashion. Spent supercritical fluid exits through outlet 46 and the upper and lower portions 44 and 48 are separated to allow the treated lens-containing mold to index out and the process to begin again.

While the step of agitating the superc, ilical fluid is desirable, it is not a required step. In a p~reiled embodiment, agildliol1 is provided by mechanical means, as shown in FIGS. 1 and 2. However, a preferred agitation state may arise merely from the apF~ tion of the superc~ilical fluid at the appr~p, iaLe pressure, i.e., a turb,ulent flow is developed by the passageway dimensions, passageway shape, and fluid pressure.

FIGS. 1 and 2 present two designs for equipment suited to treating lenses with supercritical fluids. However, a wide variety of all~l "di~/es will be readily apparent to pe,:,ons having o~ di~ lafy skill in the art, given the teachings of the pr~senL invention. Accordingly, the invention should not be strictly constrained to the designs presented in FIGS. 1 and 2.

The previous ~isclos~ ~re will enable one having ordinary skill in the art to prdc,lice the invention. In order to better enable the reader to understand specific embodiments and the advantages thereof"~ rer~nce to the f~ g examples is suggesle~

EXAMPLE l: Hydrophilic conla~l lens are formed in a double sided molding ~rucess. The concave mold halves are manually removed, leaving the lenses predominately affixed to the convex mold halves. The lenses and affixed convex mold halves are placed inside the I,eal",enl cavity of an Autoclave Engineering model EP-2000 Super~,ilical C02 Treatment System. Su~er~;,ilical carbon dioxide fluid at 3000 psig and 35~C is applied to the lenses and affixed mold halves for a period of about 100 minutes. The lenses affixed to the base-curve mold halves are not deL 1., -' ?d from the mold halves.

EXAMPLE ll: Hydrophilic contact lenses and affixed mold halves are treated as described in Example 1, with the SCF pressure at 3000 psig and temperature at 30~C. The treatment W O 96/26059 PCTAEPg~

period is about 100 minutes. The lenses affixed to the base-curve mold halves are not deblocked from the mold halves.

EXAMPLE lll: Hydrophilic contact lenses and affixed mold halves are treated as described in Example 1, with the SCF pressure at 3000 psig and temperature at 25~C. The treatmenl period is about 100 minutes. The lenses are partially, but incompletely, deblocked from thle base-curve mold halves.

EXAMPLE IV: Hydrophilic contact lenses and affixed mold halves are treated as describecl in Example 1, with the near-supercritical fluid pressure at 1000 psig and temperature at 25~C. The l,~al",enl period is about 100 minutes. The lenses are partially, but incomplEtely, deblocked from the base-curve mold halves.

E)<AMPLE V: Hydrophilic contact lenses and affixed mold halves are treated as described in Example 1, but a 19 weight percent isopropyl alcohol (IPA) t 81 weight percent carbon dioxide mixture is used, instead of the 100% carbon dioxide of Example 1. The pressure is 3000 psig while the temperature was 30~C. The treatment period is about 97 minutes. Thle lenses are de~ cksd from the base-curve mold halves.

EXAMPLE Vl: Hydrophilic contact lenses and affixed mold halves are treated as describeci in Example 1, but a 14 weight percent isopr~pyl alcohol / 86 weight pe,.;enL carbon dioxide mixture is used, instead of the 100% carbon dioxide of Example 1. The pressure is pulsed while the te""~erdl.lre is held at about 30~C. The pressure cycle includes about a 10 minute period at 3000 psig re~ /ed by a pressure drop to about 1000 psig, then a retum to the 3000 psig pressure. The l,~d~"ent period is about 81 minutes. The lenses are d~bl~ck~d from the base-curve mold halves.

EXAMPLE Vll: Hydrophilic conlacl lenses and affixed mold halves are treated as describe!d in Example 1, but a 10 weight percent isopropyl alcohol / 90 weight per ;enl carbon dioxide SCF mixture is used, instead of the 100% carbon dioxide of Example 1. The pressure is 3000 psig while the temperature is 30~C. The treatment period is about 100 minutes. The lenses are dekl~ ~'.-d from the mold halves. The average weight percent extractables in lhe lenses is about 1.6.

EXAMPLE Vlll (COMPARATIVE): H~dlupl ~ "~ contact lenses are deblocked from molds.
The lenses are immersed for about 15 hours in isopropyl alcohol. The spent alcohol is CA 022ll023 l997-07-2l W ~96126059 PCT~EP9C~

replaced with fresh alcohol, and the lenses are allowed to soak again for about 8 hours.
The average weight percent e,cl, _ '~ as in the lenses is about 1.1. Results are shown in Table I for con,,aa~ison with Example Vll.

CA 022ll023 l997-07-2l Exam Pressure Temper Exposure Composition Results ple (psig) ature Time (weight (~C)(minutes) percent) 3000 35 100 100% C02 no deblocking from base-curves Il 3000 30 100 100% C02 no deblocking from base-curves 111 3000 25 100 100% C02 incomplete deblocking from base-curves IV 1000 25 100 100% CO2 incomplete deblocking from base-curves V 3000 30 97 81% CO2 complete 19% IPA deblocking from base-curves Vl pulsed at 30 81 86% C02 complete 3000 and 14% IPA deblockingfrom 1000 base-curves negligible extractables Vll 3000 30 100 90% CO2 incomplete 10% IPA deblocking from base-curves;
1.6% extractables Vlllabout 14.7 about 211380 100% IPA 1.1% extractables (control) In all Examples, the lenses which are affixed to the front-curve mold halves are deblocked.
Variations in deblocking occur only in lenses affixed to the base-curve mold halves.

SUBSTITUTE SHEET (RULE 26) WO 96126059 PCT~P~CJ~0554 Examples V and Vl illustrate that contact lenses may be de~ ed from lens molds suhsequent to polymerization steps by a~F ic -tion of super.;~ilical carbon dioxide/isoprupyl alcohol fluids. Deblocking problems in Examples l-VI are believed to be a result of non-opli.,.i~ed condilions and/or fixturing pr~blen-s i.e. improper locdLion of the lenses and mold halves within the SCF treatment cavity.

Further a compa~iaon of Example Vll to Cc~ d~dli~re Example Vlll shows that e,~L,d.;lion of lenses with supe,~, ilical fluids produces e,~ clable levels com~Jd,dble to e~,a~ lion by batch soaki"g in isopr~pyl alcohol but over a si~. IiFicar,Lly reduced time period.

EXAMPLE IX: About 51.5 9 (50 mmol) of the perFluorupolyether Fo",bliu~ ZDOL (from Ausimont S.p.A Milan) having a mean n ole~ weight of 1030 g/mol and containing 1.96meq/g of hydroxyl groups according to end-group lil,aliGn is introduced into a three-neck flask together with 50mg of dibutyltin dilaurate. The flask contenls are ev~cu~t~d to about 20 mbar with stirring and s- ~hsequentiy decc,r. .~.r~ssed with argon. This operdlion is repeA~d twice. About 22.29 (0.1mol) of freshly distilled isopho,une diisocyanate kept under argon are s~ ~hseq~ ~ently added in a co~ ral,t:a... of argon. The te""~er&l.lre in the flask is kept below about 30~C by cooling with a w~ ll ,. After stirring overnight at room t~",peralure the reaclion is complete. Isocyanate li~alion gives an NCO conler,l of about 1.40 meq/g (theory: 1.35 meq/g).

About 202 9 of the a~hydroxypropyl-terminated poly.ii."ell,ylsiloxane KF-6001 from Shin-Etsu having a mean m~ e ~ weight of 2û00g/mol (1.00meq/g of hydroxyl groups according to till~lion) are introducerl into a flask. The flask conlenls are ev~cu~tPd to approx. 0.1 mbar and decol"pressed with argon. This operation is r~peaLed twice. The deg~cserl siloxane is dissolved in about 202 ml of freshly distilled toluene kept under argon and about 100 mg of dibutyltin dilaurate (DBTDL) are added. After CGillpl_' -.
homogeni~alio,1 of the solution all the perfluG,upolyEther (~a~ed with isopho,une diisocyanate (IPDI) is added under argon. After stirring ovemight at room temperature the .eaclion is cor, r'el ~ . The solvent is sl,iuped off under a high vacuum at room len"~e,~lure.
Mic~tiL,dlion shows about 0.36 meq/g of hydroxyl groups (theory 0.37meq/g).

CA 022ll023 l997-07-2l About 13.78 9 (88.9mmol) of 2-isocyanatoethyl methacrylate (IEM) are added under argon to 2479 of the a ~-hydroxypropyl-terminated polysiloxane-perfluoropolyether-polysiloxane three-block copolymer (a three-block copolymer on st~i ~ h;o I ,ell ic average but other block lengths are also present). The mixture is stirred at room temperature for three days.
Microlill~lion then no longer shows any isocyanate groups (deteclion limit 0.01 meq/g).
About 0.34 meq/g of methacryl groups are found (theory 0.34meq/g).

The macromer prepared in this way is completely colourless and clear. It can be stored in air at room temperature for several months in the absence of light without any change in molQcul~r weight.

About 10.0 grams of the macromer are dissolved in 3.3 grams of ethanol (Fluka puriss.
p.a.). After con ~te homogeni~aliorl of the solution about 4.0 grams of 3-tris(trimethylsiloxy)silylpropyl methacrylate (TRIS from Shin-Etsu product no. KF-2801) about 5.9 9. freshly distilled dimethylacrylamide (DMA) about 0.1 9. Blemer~ QA (a ",~I,acrylate having qual~:",ary a"""onium sllhstitllents Linz Chemie) and about 100 mg of phot- :. lilialor Darocur~ 1173 (Ciba) are added. The solution is filtered through a TEFLON n,e",brane having a pore width of 0.45 mm under an argon pressure of from about 1 to 2 atm.

The filtered solution is frozen in a flask in liquid n;l,oge" the flask is ev~cu~t~d under a high vacuum and the solution is returned to room temperature with the flask sealed. This deg~ssing operation is repe~ted twice. The flask containing the ",ac(ur,le,/cor"ono",er solution is then Ll dnsrel, ~:d into a glove box with an inert gas al,)1osphert: where the solution is pipetted into dust-free polypropylene contact lens molds. The molds are closedl and the pol~"~eli~alion reaction is effected by UV i"~.lidlion with simultaneous crossl;nhin!3.
The molds are then opened and placed in isopr~pyl alcohol causing the resultant lenses to swell out of the molds. The lenses are extracted for about 24 hours with nearly continuous r~plenishing of isopropyl alcohol. Suhsequently the lenses are dried under high vacuum.

After prepa,dlion the lenses are dried overnight under vacuum. An Autoclave Engineering model EP-2000 Supercrilical C02 Treatment System exlld.;lion vessel is loaded with 7 lenses. The e,~l,dc~ion vessel is filled with carbon dioxide and the pressure is raised to WO g6126059 PCT~P96/00554 about 200 atm with a temperature of about 30~C. The vessel is allowed to equilibrate for about 10 minutes.

The lenses are exl,dc led with an 80:20 volume/volume ratio of a carbon dioxide/isop~pyl alcohol (CO2/lPA) stream at about 200 atm and a temperature of about 30~C. The flow rate is held nearly conslanl at about 1.0 milliliters/minute. Extract is collect~d on a solid-phase adsorbent trap at about -10~C and then desorbed at about 100~C by about 3.0 milliliters of isop,upyl alcohol wash pertrap. Gravimetric analysis of extract residue c lected is performed after removing isoprupyl alcohol by ~pl ~ -tion of a nit~ùgen stream under a vacuum.

The prior exl,d-tion cycle is applied a total of 10 times. The process is repeated for another set of seven lenses. The weight per~enl extractables is determined by summing the wh~ Ls of the exl-_ -IO!~ removed and dividing this by the sum of the e~ cled lens wei~hl~. This average weight percent extractables removed is about 6.0%.

EXAMPLE X: Contact lenses are pr~pd,~d in a~,dance with Example IX. Exl,d- lion is performed suL,slar.lia 'y as described in Example IX with (a) a 70:30 CO2/lPA stream as opposed to an 80:20 stream and (b) a total number of e~ ~ion cycles of 5 rather than 10.

The average weight per ;enl ekl. ~ les determined in acco,~ance with the procedure of Example IX is about 6.1%.

EXAMPLE Xl: Contact lenses are pr~pa,~d in accGrda"ce with Example IX. ~l,d~ion is performed sul,~lanlially as described in Example IX with (a) a 70:30 CO2/lPA stream as opposed to an 80:20 stream and (b) a total number of exl,dclion cycles of 10.

The average weight per~enl exl,al t~les determined in accor~lance with the procedure of Example IX is about 6.8%.

EXAMPLE Xll: Contact lenses are pr~pa,~d in accor~lance with Example IX. Eklldction is performed sut,~lanlially as desc~ ed in Example IX with (a) a 70:30 CO2/lPA stream as opposed to an 80:20 stream and (b) a total number of e,~l~d~ion cycles of 2 rather than 10.

CA 022ll023 l997-07-2l W 096126059 PCT/~Gloo554 The average weight percent exl~ hles1 determined in accordance with the procedure of Example IX is about 4.0%.

EXAMPLE Xlll: In a dry box under nitrogen almosphere about 200 grams of dry PDMSdipropoxyethanol (Shin-Etsu) is added to a container. Isocyanaloetl,yl methacrylate (IEM) in an amount equal to about 2 moles per mole PDMS dialka,)ol is added to the container.
About 0.1 weight percent dibutyltin dilaurate (DBTL) catalyst, based on PDMS dialkanol weight is added to the container along with a stir bar. The container is immersed in an oil bath atop a stir plate, and secured in place with a clamp. A stream of UPC air at about 2 psig is passed over the mixture. The mixture is ~git~tpd at room temperature (about 22~C) for about 24 hours. An iterative procedure follows in which the mixture is analyzed for isocyanate content and IEM is added if the PDMS dialkoxyalkanol has not been completely reacted. The mixture is stirred about 24 hours more. The ~"acrc,r"er produced is a siloxane-containing "laclun,er.

A prepolyme,i~alion mixture is pl~pdl~d by mixing about 56 grams of the siloxane-containing n,a.;ro,l,er about 14 grams of TRIS about 29 grams N,N-dimethylacrylamide (DMA) about 1 gram ",t:Lhac~ylic add about 0.5 grams Darocur~) 1173 phota . ,ilidlor, and about 20 grams hexanol. The mixture is agil~Pd for about 20 minutes at room temperature.

Next, the mixture is de9a~csecl via a series of freezing and thawing steps. The container is placed in a liquid nitrogen bath until the mixture solidifies. A vacuum is applied to the container at a pressure of about 200 millitorr or less for about 5 minutes. Then the container is placed in a bath of room temperature water until the mixture is liquid again.
This process is peRormed a total of three times.

The mixture is then polymerized to form contact lenses. The prepolyme, i~dlion mixture is poured into polypropylene contact lens molds in a nitrogen al~osphere. The poly",e~i~alion is effected by applying UV rddialion (about 4~ mW/cm2) for a period of about 15 minutes.

The lenses are lldnsr~"ed into a plasma coating appdraLus wherein they are surface treated in a r"ell,ane~'air" mixture ("air" as used here denotes 79% r,il,ogen and 21%

WO 96126059 PCT~P96~00554 oxygen) for a period of about 5 minutes. The apparatus and plasma treatment process have been ~isrlQsed by H. Yasuda in rlas"~a Pol~""eli~lion Academic Press O~andoFlorida (1985) pages 319 folward.
r E~L,d~.lion of the lenses is pe~ro",)ed sub~la"lidlly as described in Example IX with (a) a 70:30 CO2/lPA stream as opposed to an 80:20 stream and (b) a total number of e~ aclion cycles of 5 rather than 10.

The average weight per~e,)l e,cL,dclables, dele""i"ed in a~rdance with the procedure of Example IX is about 0.2%.

EXAMPLE XIV- Before the reaction the amino-fu"~tionali~ed polydi "ell "~Is;loxane (a ~-bis-aminopropyl-dimethylpolysiloxane) employed for the synthesis (X-22-161-C Shin Etsu JP) was finely dispersed in acetor,il(; E ext,acted and then subjected to Illo'e~ r distillation.

The following rea~tions take place with eY.clusion of H20. About 200 g of purified amino-f~l"clional;,~d polydimethy~s- - ~rle (0.375 meq of NH2/g; Mn(VPO) 3400-3900 (VPO
Vapour Pressure Os",ol"el,y)) dissolv~d in about 200 ml of r~sol lte THF are slowly added dropwise to a suspênsion of about 13.35 9 (75 mmol) of D(+)gluconic acid d-lactone in about 50 ml of ~h5 o ut~ THF and the mixture is stirred at about 40~C for about 24 hours until the lactone has rea~ed co"" letely. (I\ls~nito,i"~ of the l~a~lion by thin layer chr~maloy,~l,y (TLC): silica gel; i-pr~ panol/H2O/ethyl ~cetrtP 6:3:1; staining with Ce(lV) sulfate/phospho~ul,)olybdic acid solution (CPS r~agenl)). After the rea-;lion the ,~~tion solution is COI ,ce"l,dled to dryness and the residue is dried under 3 Pa (0.03 mbar) for 48 hours. 213.3 9 of a~o-bis(3-gluconam:dQp~pyl)-poly-dimethylsiloxane are obtained.
Titration of the amino groups with per~;l !a. ic acid shows a conversion of the amino groups of more than 99.8%.

The product (of a ~-bis-3-glucona",:dopropyl-dimethylpolysiloxane) obtained above (about 213.3 9) is dissolved in about 800 ml of r so -~t~ THF and the solution is heated to about 40~C with the addilion of catalytic amounts of dibutyltin dilaurate (DBTDL). About 29.2 9 (187.5 mmol) of IEM in about 20 ml of r~s_' It~ THF are added dropwise to this solution over a period of about 4 hours. This corresponds to a concel-t,dlion of 1.2 equivalents of IEM per glucona",i~!o unit. The reaction is carried out in the course of 48 hours (monitoring of the reaction by IR specl,oscopy det~ction of the NCO ties). The reaction solution is concentrated and the product is dried in a brown glass flask under 3 Pa (0.03mbar) for 24 hours while cooling with ice. 227.2 9 of a colourless rubber-elastic product of high optical transparency remain.

Before the polyme,i~dlion the acrylates e",p'~yed N N-dimethylacrylamide (DMA) and 3-methacryloyloxypropyl-L,is(l,i",ell,ylsilyloxy)silane (TRIS) are each freed from i,,hibilûr~ by distillation. About 1.44 9 (about 14 mmol) of DMA and about 1.44 9 (3.4 mmol) of TRIS are weighed into a 50 ml round-bottomed flask and the flask is flushed with N2 for half an hour, while cooling with ice. About 1.44 9 of the ",ac,ul"er are transfenred to a round-bottomed flask with a nitrogen alldcl ""ent, deg~ssed under about 3 Pa (0.03mbar) for 24 hours and then dissolvcd in 2.7 9 of ethanol which has been flushed with N2 for half an hour befo,t:l1and. The s~ ~hsequent prepardlion of sa", ~ les and the poly",e,i~dlion are carried out inside a glove box with ~xcl- ~sion of oxygen. The above ",ono",er mixture and the macro",er solution with the addition of about 0.012 9 (0.21mmol) of DarocurtE~ 1173 and the mixture is subjected to ",;~ ,ur,llralion (0.45 mm filter). About 180 ~11 of this mixture are introduced into a polypropylene mould which is then closed with an app,upliale lid of polypropylene. The mixture is then illddidled with a UV-A mercury high pressure lamp in a nitrogen al",osphere in a UV oven equipped for this for 5 minutes. The lamps (5 each of the brand TLK40W/10R Philips) are above and below the holder inserted. The i"d-Jialion i,llensily is 14.5mW/cm2.

The polypropylene mold is opened and the finished discs or lenses are removed. Exl,dulion is performed subald"lially as described in Example IX with (a) a 100% CO2 stream as opposed to an 80:20 C02/lPA stream and (b) a total number of e~l,c,.;lion cycles of 10.

The average weight percent extra- ~hlss determined in accordance with the procedure of Example IX is about 1.6%.

EXAMPLE XV: Contact lenses are prepared in accorda"ce with Example XIV. Exl,aclion is perfonmed sub~lanlially as described in Example IX with (a) a 95:5 CO2/lPA stream as opposed to an 80:20 stream and (b) a total number of exl,dclion cycles of 10.

W O 96126059 PCT~Fg6/~00554 The average weight percent e~cl,_ -les determined in accorJance with the procedure of r_xample IX, is about 1.9%.

EXAMPLE XVI: Contact lenses are prepared in accordance with Example XIV. ExL,dclion is performed s~ lanlially as described in Example IX with (a) a 90:10 C02/lPA stream as opposed to an 80:20 stream and (b) a total number of e~l, d~Lion cycles of 10.

The avera~e weight percent e~ le~, deLe"";. ,ed in acco~c~al1ce with the procedure of ExampleIX isabout2.9%.

EXAMPLE XVII: Contact lenses are prepa,~d in accor~ance with Example XIV. Extraction is performed su~la"lially as described in Example IX, with (a) an 80:20 CO2/lPA stream and (b) a total number of e,~l,dl Lio,) cycles of 10.

The average weight pe~enl e..l,~clables, determined in accG,dance with the procedure of Example IX is about 4.7%.

EXAMPLE XVIII: Contact lenses are prepared in accordal1ce with Example XIV. Exl,ac~ion is pe,ro,."ed su~;,sldnlially as described in Example IX with (a) a 70:30 C02/lPA stream as opposed to an 80:20 stream and (b) a total number of e,.l,d~ion cycles of 10.

The average weight per~enl ext, . I: os determined in accor.lance with the procedure of Example IX, is about 5.6%.

W 096/26059 PCT~EP9G/OOr5 Example Percent isoprupyl Number of Non-volatile alcohol in IPA/CO2 Exlldc~ion Cycles ExLI . ' ~'es extraction fluid Removed (weight percent) I~C 20 10 6.0 X 30 5 6.1 Xl 30 10 6.8 Xll 30 2 4.0 Xlll 30 5 0.2 XIV 0 10 1.6 XV 5 10 1.9 XVI 10 10 2.9 XVII 20 10 4.7 XVIII 30 10 5.6 The invention has been described in detail, with rt:rer~nce to certain pr~rei,~dembodiments, in order to enable the reader to p, ~clice the invention without undue expe,i",enLaLion. However, a person having ordinary skill in the art will readily recognize that many of the previous co",po,1ents and pa,d",eL~ra may be varied or modified to a certain extent without depd, Ling from the scope and spirit of the invention. Ful ll ,e" "Gr~, titles, headings, or the like are provided to enhance the reader's con,p,t:hension of this document, and should not be read as limiting the scope of the pl~âer,L invention.
Accordingly, the i": lle~h~l property rights to this invention are defined only by the following claims and any reasonable e~lensions thereof

Claims

That which is claimed is:

1. A method of deblocking polymeric articles from molds comprising the steps of:
(1) providing a stream of supercritical fluid at a predetermined temperature and a predetermined pressure;

(2) contacting a hydrophilic polymeric article with the supercritical fluid for a predetermined period of time in a manner such that the polymeric article is separated (deblocked) from a mold; and (3) removing the supercritical fluid from the polymeric article.

2. A method of claim 1, further comprising the step of mechanically agitating the supercritical fluid.

3. A method of claim 1, wherein said supercritical fluid stream is provided in a turbulent flow regime.

4. A method of claim 1, wherein the polymeric article is simultaneously deblocked from the mold while undesirable materials are removed with the supercritical fluid.

5. A method of claim 4, wherein said removing involves extracting unreacted monomer, oligomer and/or solvent from the core of the polymeric article.

6. A method of claim 4, wherein said removing involves cleaning undesirable materials from the surface of the polymeric article.

7. A method of claim 1, wherein said polymeric article is selected from the group consisting of medical devices.

8. A method of claim 7, wherein said polymeric article is an ophthalmic device.

9. A method of claim 8, wherein said polymeric article is a contact lens.

10. A method of claim 1, wherein the flow rate of said supercritical fluid stream is between 0.1 and 5 gallons per minute.

11. A method of claim 1, wherein said supercritical fluid is selected from the group consisting of carbon dioxide, alcohols, hexane, acetone, sulfur hexafluoride, and mixtures thereof.

12. A method of claim 11, wherein said supercritical fluid is selected from the group consisting of carbon dioxide, isopropyl alcohol, and mixtures thereof.

13. A method of claim 12, wherein said supercritical fluid is carbon dioxide.

14. A method of claim 12, wherein said supercritical fluid comprises:

(a) 70 to 99 weight percent carbon dioxide; and (b) 1 to 30 weight percent isopropyl alcohol.

15. A method of claim 14, wherein said supercritical fluid comprises;

(a) 75 to 85 weight percent carbon dioxide; and (b) 15 to 25 weight percent isopropyl alcohol.

16. A method of claim 1, wherein said pressure is between 600 and 5000 psia and said temperature is between 21 and 45°C.

17. A method of claim 16, wherein said pressure is between 900 and 3000 psia and said temperature is between 21 and 35°C.

18. A method of claim 1, further comprising the step of mechanically agitating the supercritical fluid to produce a turbulent flow regime, wherein said supercritical fluid comprises 70 to 99 weight percent carbon dioxide and 1 to 30 weight percent isopropyl alcohol, wherein the flow rate of said supercritical fluid stream is between 0.1 and 5 gallons per minute, and wherein said polymeric article is an ophthalmic device.

19. A method of removing undesirable materials from hydrophilic polymeric articles, comprising the steps of:

(1) providing a stream of supercritical fluid at a predetermined temperature and a predetermined pressure;

(2) contacting a hydrophilic polymeric article with the supercritical fluid for a predetermined period of time in a manner such that undesirable materials are removed from the hydrophilic polymeric article; and (3) removing the supercritical fluid from the hydrophilic polymeric article.

20. A method of claim 19, further comprising the step of mechanically agitating the supercritical fluid.

21. A method of claim 19, wherein said supercritical fluid stream is provided in a turbulent flow regime.

22. A method of claim 19, wherein the polymeric article is simultaneously deblocked from a mold while undesirable materials are removed with the supercritical fluid.

23. A method of claim 22 wherein said removing involves extracting unreacted monomer, oligomer and/or solvent from the core of the polymeric article.

24. A method of claim 22, wherein said removing involves cleaning undesirable materials from the surface of the polymeric article.

25. A method of claim 19, wherein said polymeric article is a medical device.

26. A method of claim 25, wherein said polymeric article is an ophthalmic device.

27. A method of claim 26, wherein said polymeric article is a contact lens.

28. A method of claim 19, wherein the flow rate of said supercritical fluid stream is between 0.1 and 5 gallons per minute.

29. A method of claim 19, wherein said supercritical fluid is selected from the group consisting of carbon dioxide, alcohols, hexane, acetone, sulfur hexafluoride, and mixtures thereof.

30. A method of claim 29, wherein said supercritical fluid is selected from the group consisting of carbon dioxide, isopropyl, alcohol, and mixtures thereof.

31. A method of claim 30, wherein said supercritical fluid is carbon dioxide.

32. A method of claim 30, wherein said supercritical fluid comprises:

(a) 70 to 99 weight percent carbon dioxide; and (b) 1 to 30 weight percent isopropyl alcohol.

33. A method of claim 32, wherein said supercritical fluid comprises:

(a) 75 to 85 weight percent carbon dioxide; and (b) 15 to 25 weight percent isopropyl alcohol.

34. A method of claim 19, wherein said pressure is between 600 and 5000 psia and said temperature is between 21 and 45°C.

35. A method of claim 34, wherein said pressure is between 900 and 3000 psia and said temperature is between 21 and 35°C.

36. A method of claim 19 further comprising the step of mechanically agitating the supercritical fluid to produce a turbulent flow regime, wherein said supercritical fluid comprises 70 to 99 weight percent carbon dioxide and 1 to 30 weight percent isopropyl alcohol, wherein the flow rate of said supercritical fluid stream is between 0.1 and 5 gallons per minute, and wherein said polymeric article is an ophthalmic device.

37. A method of claim 36 wherein the ophthalmic device is a contact lens.

38. A method of removing undesirable materials from a medical device or component thereof, comprising the steps of:

(1) providing a stream of supercritical fluid at a predetermined temperature and a predetermined pressure;

(2) contacting a medical device with the supercritical fluid for a predeterminedperiod of time in a manner such that undesirable materials are removed from the medical device; and (3) removing the supercritical fluid from the medical device.

39. A method of claim 38, further comprising the step of mechanically agitating the supercritical fluid.

40. A method of claim 38, wherein supercritical fluid stream is provided in a turbulent flow regime.

41. A method of claim 38, wherein the medical device is simultaneously deblocked from a mold while undesirable materials are removed with the supercritical fluid.

42. A method of claim 41, wherein said removing involves extracting unreacted monomer, oligomer, and/or solvent from the core of the medical device.

43. A method of claim 41, wherein said removing involves cleaning undesirable materials from the surface of the medical device.

44. A method of claim 38, wherein said medical device is an ophthalmic device.

45. A method of claim 45, wherein said medical device is a contact lens.

46. A method of claim 38, wherein the flow rate of said supercritical fluid stream is between 0.1 and 5 gallons per minute.

47. A method of claim 46, wherein said supercritical fluid is selected from the group consisting of carbon dioxide, alcohols, hexane, acetone, sulfur hexafluoride, and mixtures thereof.

48. A method of claim 47, wherein said supercritical fluid is selected from the group consisting of carbon dioxide, isopropyl alcohol, and mixtures thereof.

49. A method of claim 48, wherein said supercritical fluid is carbon dioxide.

50. A method of claim 48, wherein said supercritical fluid comprises:

(a) 70 to 99 weight percent carbon dioxide; and (b) 1 to 30 weight percent isopropyl alcohol.

51. A method of claim 50, wherein said supercritical fluid comprises:

(a) 75 to 85 weight percent carbon dioxide; and (b) 15 to 25 weight percent isopropyl alcohol.

52. A method of claim 38, wherein said pressure is between 600 and 5000 psia and said temperature is between 21 and 45°C.

53. A method of claim 52, wherein said pressure is between 900 and 3000 psia and said temperature is between 21 and 35°C.

54. A method of claim 38, further comprising the step of mechanically agitating the supercritical fluid to produce a turbulent flow regime, wherein said supercritical fluid comprises 70 to 99 weight percent carbon dioxide and 1 to 30 weight percent isopropyl alcohol, wherein the flow rate of said supercritical fluid stream is between 0.1 and 5 gallons per minute, and wherein said polymeric article is an ophthalmic device.

55. A method according to claim 1 wherein the polymeric article is a contact lens prepared from a mixture comprising a copolymerizable macromer and two or more copolymerizable monomers.

56. A method according to claim 19 wherein the polymeric article is a contact lens prepared from a mixture comprising a copolymerizable macromer and two or more copolymerizable monomers.

57. A method according to claim 38 wherein the polymeric article is a contact lens prepared from a mixture comprising a copolymerizable macromer and two or more copolymerizable monomers.