Polysiloxane composition and contact lens

BACKGROUND OF THE INVENTION ___ ~ _ Fleld of the Invention . .

This invention relates to novel polymeric compositions and more particularly to contact lenses made therefrom. These contact lenses comprise fillerless, oxygen transportable, hydrolytically stable, biologically inert, transparent, contact lenses prepared from the polymerization of monomers which are poly(organosiloxanes) a,~ terminally bonded through divalent ...~, ~.

.

z~ 1 hydrocarbon groups to activated unsaturated groups.

The invention further particularly relates to polymers and/or copolymers wh~ch comprise poly(organosiloxanes) terminally bonded through diva~ent hydrocarbon groups to act~vated unsaturated groups copolymerized with monomers conta~ning activa~ed ~inyl groups.

The copolymers are optically clear, and colorless. me polymers and copolymers descr~bed herein can be use~ully employed ~or, as stated, making "hard" or "so~t" contact lenses, intraocula~ implants, as well as other prosthesesg more particularly "soft" con*act lenses.

PRIOR ART STATEMENT ~he use of ~iloxane polymers ~or the fabrication ol ~ptical contact lenses is desirable.

Ihe desirabillty is due to the high ox~gen transportability and generally the relative softness o~ polysiloxanes. l~e tear ~trength and tensile strength of polysiloxane elastomers, however, are generally poor and as a result ~illers are employed to ~ncrease the strength of the elastomers.

In U.S.

Patent Nos. 3~9g6~187~ 3,996~189, 3,341,490 and 3,228,741 there are described ccntact lenses ~abricated ~rom poly~organosiloxanes) containing fillers.

2~ me *ear strength and tensile strength o~ the con'act lenses made ~rom the instant polymer are Or su~ficient strength so that no 1 fillers are requlred.

U. S.

Patents 3,996~187 and 3,996,189, as mentioned above, disclose contact lenses made from reinforced polysiloxanesO The lenses contain various polysiloxanes with index of refractions similar to the sillca flller so that an optically clear silica filled silicone elastomer can be formed from aryl and alkyl slloxanes.

The material contains from 5 to 20 percent silica.

The sllica is used, as mentioned, for strength.

The instant invention contains no fillers for strength since the instant material has sufficient strength without fillers.

U. S.

Patent 3,341,490 discloses contact lenses made from blends of siloxane copolymers containing reinforcing silica fillers.

As mentioned, the contact lenses of the instant invention contain no fillers.

U. S. 3,228,741 discloses contact lenses made from silicone rubber particularly hydrocarbon substi~uted polysiloxane rubber.

This silicone material contains fillers such as pure silica to control flexibility, pliability and resiliency of the lenses.

The instant polymers require no fillers.

U. S.

Patent 3g808,178 discloses a polymeric material containing a polymethacrylate backbone with relatively short poly (organosiloxane) ester side chains on the backbone polymer.

There îs no cross-linking involved in '178 since the monomers disclosed in ~178 are monofunctional i.e. have only one functional group on each monomer.

In order to get cross-linking in '178 it is taught at column 5 of '178 that different monomers must be added for cross linking which have more than one functionality.

However, in the instant ir.vention cross-linking is obtained since each 14 1 siloxane monomer is difunc~ional i.e. each monomer contains two functional groups, most preferably two methacryla~e ~-oups which results in cross-llnking.

Furthermcre, contact lenses made ~rom the polymers disclosed in '178 would not transport oxygen su~riciently whereas contact lenses made from the instant polymers would transport oxygen sufriciently to meet the re~ulrements o~ the h~man cornea.

~. S~ Patent 3,518~324 te~ches vulcanizlng to make silicone - rubber whereas the ins~ant lnvention iS concerned with contact lenses made from polymerizing speci~lc monomers.

U. S.

Patent 3,878,263 teaches one con~iguration whlch may be (R~ = C - C - OR" - 5~O3 ~ ~ zSi~ c Rs may be monovalent hydrocarbons.

~' may be a mono~alent hydrocarbon.

c may equal zero hut whe~ c ff~ls~2ero ~en ~t le~s~ o~e Zn~st be OR"".

Z is an important ingredient since this is used to-crosslink the chains.

Therefore, the monomers o~ the instant invention are not taught in '263.

U. S.

Patent 2,770,633 discloses-1,3~bis(4-methacryloxyb~tyl) tetramethyl disiloxane, one of the preferred monomers used in the instant invention. m is is tau~ht at column 1, llne 63 of '633 when R e~uals vlnyl. ~owever, '633 teaches only the monomer whereas the instant invention teaches not only the monomer but the polymer.

In ract '633 would not want the monomer to polymerize since it would 3 not perform its function as a lubricant i~ polymerized.

.

2~34 1 U. S.

Patent 2,906,735 teaches a reaction between an alkyl siloxane and acrylic acid or a methacrylic acid resultlng in a disiloxane terminated by acrylate groups. '735 does not `teach the polymers of the instant invention.

U. S.

Patent Z,922,807 disGloses disiloxanes ~aving acryloxy or methacryloxy groups attached to the silicone through a divalent alkylene radical of from 2 to 4 carbon atoms.

None of the above patents teach the instant invention much less the preferred reactions of the instant invention which is 1,3-bis(4-methacryloxybutyl) tetramethyl disiloxane reacted with preferably octamethyl cyclotetrasiloxane to form the preferred monomer.

This preferred monomer is then polymerized to the preferred cross-linked polymer of the instant invention.

Furthermore, and most importantly, none of the prior art teaches novel contact lenses of the instant ~nvention made from the instant polymers.

U. S. 3,763,081 disclosesg in pertinent part, the polymerization of an unsaturated siloxane which is somewhat difficult to polymerize since a double bond in this type of monomer generally is not very active.

One must use both high temperatures and a peroxide catalysis or a platinum catalysis in order to complete this type of reaction.

See~ for exampleg '081 at column 4 lines 55-46.

In the instant reaction the monomeric materials are referred to specifically as having activated unsaturated groups bonded througb a divalent hydrocarbon group to the siloxane whereas '081 has no activated unsaturated groups bonded to the siloxane.

U. S.

Patent 2,865,885 in pertinent part teaches a vinyl group which is not activated as shown in column 1 lines 25-30 of 24~34 1 ~885.

The reason ~885~s double bond is not "acti~e" in the sense as defined in the instant application is that the double bond is bonded to either sulfur or oxygen.

In the instant invention this same positlon would have a (-c-) carbony]. group.

This would make the double bond active as defined in ~he instant appl~cationO There~ore, in ' 885 since the reactivity ratios are so different i.e. the double bond is not active in ' 885 as defined in the instant invention, it would be very di~ficult to get an acceptable copolymeriæation reaction using the formulae of ' 885 as compared to the active double bond in the instant invention whlch easily copolymerizes.

In the instant invention the vinyl group is ~'activated" to facilitate free radical polymeriæation.

The formula given at column 1, lines 25-30 o~ ' 885 does not lend itself to free radical polymerization due to the lack of resonance ~ut rather it lends itself to ionic polymerlzation due to the polar nature of the substituents~ Therefore, it would be extremely difficulk, if at all posslble, for ' 885 to form the compounds of the lnstant invention.

Also the compounds formed in ' 885 are not hydrolytically stable because of ~he presence of the siliconenitrogen bond ~n the formula.

The lnstant invention cannot use a hydrolytically unstable compound.

Furthermore, the products o~ this hydrolysis in ' 885 could be injurious to the human eye particularly the amines. AIso at column 3 of ' 885 the linkage is an amine linkage to the double bond and in the instant invention this linkage is always an alkyl.

Therefore, '885 does not teach the instant monomers.

U. S. patent 2~7939223 in pertinent part at Example 5 at -~ja 4~3~ column 3, lines 30-41 teaches that a phen~l group is attached to the siloxane. Therefore, that material would be very hard and opaque. This would be unsuitable for contact lens which must be transparent. Furthermore, contact lenses made ~rom the polymers made from the monomers disclosed in '223, because of the presence of the phenyl group on the siloxane as shown in Example 5 of '223, would not transport o~ygen sufficiently whereas contact lenses made from the instant pol~me~s would transport oxygen sufficiently to meet the re~uirements of the human cornea.

S~RY OF TH~ I~VENTION The present invention provides materials which can be usefully employed for the fabrica-tion of prostheses such as heart valves and intraocular lenses, as optical contact lenses or as films. ~ore particularly, the instant invention concerns contact lenses.

In one embodiment of this invention is provided fillerless, oxygen transporting, hydrolytically stable, biologically inert, transparent contact lenses comprising a cr~ss-linked polymer made from a poly(organosiloxane~ terminally bonded through a divalent hydrocarbon group to a polymerized activated unsaturated group.

~ hen the term "activated" is used with the term "unsaturated group" herein, it is meant that an unsaturated group which is activated is one which has a substituent which facilitates free radical polymerization. These activated unsaturated groups are polymerized to form the polymers of the instant invention. Preferably~ the activating groups used herein lend themselves to polymerization under mild conditions, such as, ambient temperatures.

When the statement is made "a poly(diorganosiloxane) , - , ` ~ 248~ 1 terminally bonded through a divalent hydrocarbon group to a polymerized activated unsaturated group" it is meant that the poly(organosiloxane) compound as described herein has been attached to a compound having a divalent hydrocarbon group~ such as, methylene or propylene etc. and then at each end of khis compound is attached an activated unsaturated group such as methacryloxy etc. and this then is the most preferred monomer.

Then when the monomers are polymerized ~i.e. cross-linked) the activated unsaturated groups are polymerizated (free radical polymerization) then the monomers form three dimensional poly mers which is the material of which the contact lens are made.

The monomers employed in accordance with this invention~ as a result o~ the presence of the activated unsaturated groups, are readily polymerized to form three dimensional polymeric net works which permit the transport of oxygen and are optically clear,strong and can be made, as desired, soft or hard.

When the term monomer is used herein we mean to include polysiloxanes end-capped with polymer~zable unsaturated groups.

The process of lengthening the siloxane portion of the monomer is referred to herein as siloxane ring insertion. The chain length of the polysiloxane center unit of the monomers may be as high as 800 or more.

When the term polymerization is used herein we refer to the polyrnerization o~ the double bonds of the polysiloxanes end capped with polymerizable unsaturated groups which results in across-linked three dimenslonal polymeric network.

-c~a 8~ 1 The rela~ive hardness (or so~tness) o~ ~he contact lenses, i~e. polymer, o~ this invention can be varied by decreasing or increasing the molecular weight o~ the monomeric poly(organosiloxane) end~capped with the activated unsatured groups or by varying the percent of the comonomer.

As the ratio of organosiloxane units to end cap units increases the so~tness of the material increases.

Conversely, as this ratio decreases the rigidity and hardness of the material lncreases.

More preferably there is provided a fillerless, oxygen transporting, flexible, hydrolytically stable, biologically - inert, transparent, resllient, soft, polymeric c~ntac~ lans comprls~ng a poly(organosiloxane~ terminally bonded through a divalent hydrocarbon group to a polymerized activated unsaturated group.

This preferred contact lens may be ~ormed by spin-casting, if desired, such as taught in U. S. patent 3,408,429. In another embodiment of this invention there are pro~ vided polymerizates comprising a poly(organosiloxane) ~,~ terminally bonded through a divalent hydrocarbon ~roup to an activated unsaturated group copolymerized with one or more monomers which can be one Or lower esters of acryllc or methacry lic acid, styryls, allyls or vinyls.

The copolymers are in the form of three dimensional networks which are clear, strong and can be usefully employed in providing films, and shaped bodles such as contact lenses.

~IL&;2~ 1 The novel copolymers of this invention can comprise 10 to 90 parts by weight of one or more o~ the monomers o~ (organosiloxanes) described herein and 90 to 10 parts by weight o~ the polymerizable monomers. The preferred contact lenses formed from these copolymers are fillerle~s 9 oxygen ~ransporting, flexible, hydrolytically stable~ biologically inert, transparent J resilient and soft.

The three-dimensional network polymer products of this invention are readily prepared by means of conventional free radical polymerization techniques. The monomers of organoslloxane alone or in the presence of comonomers together with a~out 0.~5 to about 2% by weight of a free radical initiator may be heated to a temperature of about 30C to about 100C to initiate and complete the polymerization. The polymerizable monomers i.e., the poly~organosiloxane), with or wlthout comonomers can pre~erably be sub~ected at room temperature to irradiation by W light in the presence of suitable activators such as benzoin, acetophenone, benzophenone and the like ~or a sufficient time so as to form a three dimensional polymer network.

The polymerization can be carried out directly in contact lens molds or can be cast into discs, rods or sheets which can then be fabricated to a desired shape.

Preferably khe polymerization is carried out while the material is being spin cast such as taught in U. S. patent 3~408,429.

As is well established, the oxygen transportability of polysiloxanes is substantially greater in comparison to the conventional contact lens polymers such as polymethyl methacrylate (PMMA) or polyhydroxyethylmethacrylate (PHEMA).

The oxygen transportability of the materials of this invention can be ~Z~8~ 1 varied by altering the percentage of siloxane units.

For example, a high percentage of siloxane units results in a product more capable of transporting oxygen as compared with a lower percentage of siloxane units which results ln a material with less ability to transport oxygen.

DESCRIPTION OF PREFERRED EMBODIMENTS In accordance with one embodlment of this lnvention optical contact lenses are provided which are fabricated from three-dimensional network polymerizates of poly(organosiloxanes) a,~ terminally bonded through a divalent hydrocarbon group to a polymerized activated unsaturated group. ~ypically, the poly(organosiloxanes) i.e. monomers~ employed are o~ the formula:

~ 3 ll A-R-Si t-s~- o-Si-~-A wherein A is an activated unsaturated group, R is a divalent hydrocarbon radical having from 1 to about 22 carbon atoms, Rl, R2, R3 and R4 can be the same or di~ferent and each is one of a monovalent hydrocarbon radical or a halogen substituted monovalent hydrocarbon radical each having from 1 to about 12 carbon atoms and m is O or greater.

Desirably m can be in the range of 50 to about 200.

However~ the range o~ m can be greater such as preferably 50 to 800. However, m can be greater than 800.

Should one desire to obtain a harder contact lens m should be less than 25.

1 When the term "soft'l is used herein to describe the contact lenses of the instant inventlon it ls meant that m, in the above formula~ after polymerization, is more than 25, pre~erably from about 50 about 800. W~.en the term "hard' i~ used herein to describe the contact lensl~s of the instant invention~ it is meant that m, in the above formula, a~ter polymerization, is less than 25.

- Preferably A is one of 2 - cyanoacryloxy l CH2 = C - C - O C - N g acrylonitryl CH = C C ~ N acrylamido CH2 ~ CH - C - NH - , acryloxY O CH2 = CH ~ ~ - 0 - , methacryloxy CH2 = f C o styryl CH = CH2 3 1 and N - ~inyl - 2 - pyrrolidinone ~ x yl wherein x may be 3, 4 or 5 CH - CH2 CH - CH - N + C - CH2 3 More pre~erably A is acryloxy or methacryloxy. However~ other groups containing activated unsaturation can be readily employed, such groups being well known to those skilled in the ar~. Most preferably A is methacryloxy or acrylamido. R may be preferably an alkylene radical. There~ore, preferably R~is methylene, propylene~ butylene, pentamethylene, hexamethylene, octamethylene, dodecylmethylene, hexadecylmethylene and octadecylmethylene; arylene radicals such as phenylene~ biphenylene and t,he corresponding alkylene and arylene radicals.

More~preferable R is an alkylene radical having about 1, 3 or 4 carbon atoms. Most preferably R is ~n alkylene radical havlng from about 3 to 4 carbon atoms e.g. butylene. Preferably, Rl, R2, R3 and R4 are alkyl radicals having ~rom 1 to 12 carbon atoms, e.g., methyl, ethyl, propyl, butyl, octyl, dodecyl and the llke; cycloalkyl radicals, e.g.~ cyclopentyll cyclohexyl, cycloheptyl and the like;

mononuclear and binuclear aryl radicals, e.g., phenyl, naphthyl and the like; aralkyl radicals, e.g., benzyl~ phenylethyl, ~Q24~3~ .

1 phenylpropyl, phenylbutyl and the like; alkaryl radicals, e.g., tolyl, xylyl, ethylphenyl and the like; haloaryl radicals such as chlorophenyl, tetrachlorophenyl, difluorophenyl and the like; halo substituted lower alkyl radicals having up to about ~our alkyl carbon atoms such as floromethyl and floropropyl.

More preferably Rl, R2, R3 and R4 are methyl ~adi~cals and phenyl radicals, most preferably Rl, ~2' R3 and R4 are methyl radicals.

The activated unsaturated group end-capped polysiloxanes~ i.e. monomers, employed in this invention can be prepared by equilibrating the appropriately substituted disiloxane, for example, 1,3 bis(4-methacryloxybutyl) tetramethyl disiloxane 3 with a suitable amount of a cyclic diorganosiloxane, e.g., hexamethyl cyclotrisiloxane, octaphenyl cyclotetrasiloxane, hexaphenylcyclotrisiloxane, 1,2,3~trimethyl- 1,2,3-triphenyl cyclotrisiloxane~ l,2,3,4-tetramethyl- 1,2,3,4-tetraphenyl~ cyclotetrasiloxane and the like in the presence of an acid or base catalyst.

The degree of softness, the physical properties such as tensile strength, modulus and percent elongation will determine the amount of cyclic diorganosiloxane equilibrated with the disiloxane.

By increasing the amount of cyclic siloxane one increases m.

The reaction between a cyclic diorganosiloxane and disiloxanes~ although not specifically disclosed for the disiloxanes employed in this invention as to provide the activated unsaturated groups as the end caps for polysiloxanes, is a conventional reaction and described by, for example, Ko~ima et al.

~z~ 1 Preparation of Polysiloxanes Having Terminal Carboxyl or Hydroxyl Groups, J.

Poly.

Sci., Part A-l, V~l. 4, pp 2325-27 (1966) or U. S. P~tent No. 3,878,263 o~ Mart~n issued Aprll 15, 197~ ~he following reactions represent the most pre~erred materlals of the instant inYentiOn. 1,3-bis~hydroxyalkyl) tetra~ methyl disiloxane dimethacrylates are prepared by ~he following reactions: (1) e~terlfication w~th acryloyl or methacryloyl chlorlde or anhydr~de.

For example5 the following is with methacryloyl chloride: .

IH3 3 HO ~CH2~n Si - O ~ CH2tn OH - CH3 3 n pre~erably = 1S3 and 4 CH3 I n most pre~erably - 3 or 4 2 CH = - C - Gl ~1, CH3 ~ 1H3 1 3 ~ ~H3 C O ~GH2~ i - O ~ C 2 n ~5 GH2 CH3 CH3 2 n pre~erably = 1,3 or 4 n most pre~erably - 3 or 4 (2) Another most pre~erred method of prepari~g 1,3~bis(hydroxyalkyl) tetramekhyl disiloxane dimethacryla~es is by transesteri ~ ............................................. .

-'3 :

8~L 1 fication with methyl methacrylate:

CH 0. CH CH 1 3 1l ~ 3 1 3 2 CH2 = C - C - 0 - CH3 + H0 ~CH2~nli - 0 - ~i 4CH2~noH CH3 CH3 IH3 ~o IH3 ICH3 0 ~1 ICH3 CH = C - C - 0 ~CH2~n li -- 0 ~ CH2~n 2 CH3 CH3 n preferably = 1,3 or 4 n most preferably ~ 3 or 4 , :

. Then the number of siloxane groups between the two methacrylate caps can be increase~ ~rom 2 to 2~4X by a ring opening insertion reaction with X moles of octamethyl cyclotetrasiloxane as follows:

CH 0 CH CH 0 CH 1 3 ll 1 3 1 3 11 ~ 3 CH = C - C ~ ~CH2~n li - 0 ~ CH2~n 2 CH3 CH3 n preferably = 13 3 or 4 n most preferably = 3 or 4 ICH3 CH3 CH - li - 0 - Si - CH3 X moles 0 0 CH - Si - 0 - Si - CH 3 1 1 3 3 ¦ 3 1 IH3 ~i iCH3 / f 3 \ f 3 ~ CH3 Il ~ 2~n t fi-o t Si ~CH2~n e 2 CH3 ~ J CH~ n preferably = 1~ 3 or 4 m preferably = S0 to 800 n most preferably = 3 or 4 (cross linklng/polymeri2ation) ~ / : '` (three dimensional network) ~ ~, O IC~I3 /1CH3 \ ICH3 l CH3 - IC - C0 ~CH2~n 1fi ~ fi ~CH2~n 0 ~ C - C - CH3 ~ CH3 ~CH3 ~ n CH3 ~ H2 ll ¦CH3 ~I 3 ~ I 3 1l l H2 3 f 2~n li t fi - t si ~CH2~n 0 - C - C - CH ¦ 3 ~ 3 ~ 3 CH CH 1 2 . 1 2 lH2 1 2 ~ . CH3 - C - C n preferably = 1, 3 or 4 n most preferably - 3 or 4 m preferably = 5~ to 800 `~ / ~¢~Z~ l The poly(organosiloxanes) ~,~ terminally bonded through a dlvalent hydrocarbon group ~o an activated unsaturated group iOe. the monomers herein, are generally clear, colorless liqulds whose viscosity depends on the value o~ m.

These monomers can be readily cured to cast shapes by conventional methods such as W polymerization, or through the use of ~ree radical initiators plus heat. lllustrative Or free radical initiators which can be employed are bis(ispropyl) peroxy dicarbonate, azobisisobutyronitrileg acetyl peroxide, lauroyl peroxideg decanoyl peroxide, benzoyl peroxide, tertiarybutyl peroxypivalate and the llke.

In order to further control the properties o~ the polymers of the instant invention one can polymerize a mixture of the monomers comprising monomers having a low value of m and monomers having a high value for mO When m has a low value i.e., below 25, the resulting contact lenses i.e. polymersg are relatively hard, oxygen transporting, hydrolytically stable, biologically inert, transparent and do not need fillers to improve the mechanical properties.

The monomers have a relatively low molecular weight and as a result the viscosity is low enough e.g.

about 3 centistokes so that the lenses may be made easily by spin casting.

When m has a relatively high value i.e.~ above 25, the resulting contact lenses i.e. polymers, become relatively soft, oxygen transporting, flexibleg hydrolytically stable, biologically inert, transparent, resilient, and do not need ~illers to improve the mechanical properties.

The monomers should have preferably a molecular weight low enough so that the viscosity is low enough to spin cast the monomers e.g. about 175 stokes or below measured in Gardner viscosity tubes.

Pre~erably m ls about 50 to 800.

~24~ 1 In accordance with another embodlment o~ this invention there are provided polymers of monomers which are poly(organosiloxane) terminally bonded through a dlvalent hydrocarbon group to an activated unsaturated group copolymerized with monomers containing an activated vinyl group.

The comonomer can be any polymerizable monomer which readily polymerizes by free radical polymerization and pre~erably is a monomer containing an activated vinyl groupO Through the addition of comonomers one can enhance particular desirable properties. ~or example, buttons fabricated ~rom copolymers of the lnstant monomers of the poly(siloxanes) and tetrahydrofurfuryl methacryIate can be more easily lathed into contack lenses as compared with buttons i.e. polymers, made from monomeric polysiloxanes alone.

Wettability of contact lenses i.e. polymers, ~abricated from the polysiloxanes can be substankially increased by copolymerizing the instant monomers with N-vinyl pyrrolidone.

Illustrative of comonomers which can be usefully employed in accordance with this invention are:

The derivatives of methacrylic acid, acrylic acidg itaconic acid and crotonic acid such as:

methyl, ethyl, propyl, isopropyl, n-butyl, hexyl, heptylg aryl, allyl, cyclohexyl, 2-hydroxyethyl, 2 or 3hydroxypropyl, butoxyethyl, methacrylates; and propylg isopropyl, butyl, hexyl, 2-ethyl hexyl, heptyl, aryl, acrylates; and propyl, isopropyl, butyl, hexyl, 2~ethyl hexyl, heptyl, aryl, itaconates;

and propyl, isopropyi, butyl, hexyl~ 2-ekhyl hexylS heptylg aryl, crotonakes.

-17 1 Mono or di esters of the above mentioned acids wi~h polyethers of the below general ~ormula may be used:

HO(cnH2nO}qH wherein n is a number of ~rom 1 to about 12~ preferably 2 or 3, and q is a number of rrom 2 to about 6 pre~erably 2 to ~ , .

Other comonomers may include:

styryls~ such as, styrene, divinyl benzeneg vinyl ethyl benzene, vinyl toluene etc.

Allylic monomers, such as, di allyl diglycol di~ar= bonate, allylcyanide, allyl chloride, diallyl phthalate, allyl bromide, dlallyl fumarate and diallyl carbonate may be used.

Nitrogen containing monomers can be also used~ such as:

n-vinyl pyrrolidone, 3-oxybutyl acryamide, etc.

The lower the value of m in the formula for the instant monomers the more compatible are the monomers with the above men tioned comonomers.

The advantages of using the contact lenses i.e. polymers, o~ the instan~ invention which are made from the monomers disclosed herein are numerous.

For example, (1) the advantages of using activated vinyl terminal groups to cure the siloxane material are (a) the high reactlvity systems permit rapid cure at room temperature if suitable initlators are used.

Room temperatures are preferred~ This is desirable since the preferred method of casting is spin casting. (b) No fillers are needed to get useful physical strength as is common with most silicone resins.

This is desirable since the use of fillers requires that other possibly undesirable ` 1 materials be added to the composition in order to correct the refractlve index. (2) Furthermore9 the contact lenses made from the polymer of the lnstant inventlon are oxygen transportw lng.

The human cornea requires about 2 x 10-5 cm3/ (sec. cm2 atm.) of oxygen through the contact lens as reported by Hill and ~att, American Journal o~ Optometry and Archives of the Amerlcan Academy of Optometry, Vol. 47, p. 50, 1970.

When m is at least about 4 the chain of siloxane is long enough in the instant composlti~n to exceed the oxygen transportability requirements of the cornea.

However, in specific situations m may be as low as 0.

Because of the unique properties of the contact lenses i.e. polymers, of the instant invention m may be great enough to allow sufficient oxygen transportability and at the same kime still retain its desirable properties of elasticity, tear resistance~ ~lexibility~ res~lience and softness.

When the term oxygen transportability or oxygen transporting is used in the instant application it is meant that the material will allow sufficient transmission of oxygen through itself to supply the necessary oxygen requirements of the human cornea.

The oxygen requirement ~or the human cornea as mentioned, is about 2 x 10-6 cm3/ (sec. cm2 atm.).

The oxy~en transportability was determined by a special test procedure described in con~unction with Example 10 herein. (3) These lenses are hydrolytically stable meaning that when the contact lenses are placed into an aqueous solution3 e.g.g in the eye~ or during the disin~ecting step, i.e. water plus heat, the lenses will not change in chemical composition, i.e. hydrolyze, which would cause the lenses to change shape resulting in an undesirable change in optics.

(4) The more preferred contact lenses of the instant invention 8~ 1 are also resilient. ~hen the kerm resilient is used herein it is meant that after the lenses have been deformed the lenses will return quickly to their original shape. ~5) The lenses are preferably made by spin casting, e.g. by the method as disclosed in U.S. 3,408~429.

Monomers which have too high a vlscosity cannot be spin cast.

However~ generally the higher the molecular weight of the monomers the longer the chain lengthg i.eO the larger the value of m, and as a consequence the more desirable the properties are for the preferred contact lenses i.e. polymers, of the instant invention, made from these monomers.

The longer the chain length and the higher the molecular weight the higher the viscosity of the monomers.

However, if spin casting is to be used the viscosity of the monomers must be such that these materials can be spin cast.

The monomers of the ~nstant invention can have molecular weights high enough to gIve all the desirable properties when polymerized but low enough to be spin cast while still in the monomeric form.

The preferred weight average molecular weight is from about 4,000 to 60,000 for the monomers of the instant invention. (6) The most preferre~ contact lenses o~ the instant invention should be soft.

By the use of the term "soft" in the instant applicatlon it is meant in the preferred embodiment that the lenses should have a Shore hardness of about 60 or below on the A scale. (7) The preferred contact lenses o~ the instant invention should be flexible.

When the term "flexible" is used herein, it is meant that the contact lens is capable of being folded or bent back upon itself without breaking.

The most prefer~ed contact lens of the instant invention is a fillerless, oxygen transporting, flexible~ hydrolytically stable, biologically inert, transparent, resilient, soft a polymeric contact lens comprising a poly(organosiloxane) terminally bonded through a divalent hydrocarbon group to a polymerized activated unsaturated ~Z489L 1 group.

The poly(organosiloxane) monomer used to make the polymer ~rom which the contact lens is made has the formula in the most preferred embodiment of the instant inventlon of A - R - Si ~ 0 - S1 - R A wherein A is selected from the group consisting of methacryloxy and acryloxy, R is an alkylene radical having from about 3 to about 4 carbon atoms and m is from about 50 to 800~ The most preferred contact lenses i.e. polymers, of the instant invention, as mentioned, are fillerless, have an oxygen transport rate of at least about 2 x 10 6 cm3/ (secO cm2 atm.~, are hydrolytically stable, biologically inert, transparent, resillent, and have a softness preferably of about 60 or below on the Shore - hardness A scale.

Most preferably the Shore hardness should be .

25 to 35 on the A scale.

To further illustrate the most preferred contact lenses o~ the instant invention's physical properties, the tensile modulus of elasticlty should be about 400 g/mm/mm2 or less.

Both the Shore hardness and modulus are related to the com~ort of the lenses to the wearer when used on the human eye.

Another advantage of the preferred soft contact le~ses o~ the lnstant invention is that lenses made from the polymers o~ the instant inventlon can be made large enough to cover the entire cornea of the eye resulting in more com~ort.

Hard contact lenses, such as PMMA lens, have to be made smaller due to their poor oxygen transportability.

Furthermore, the larger the lenses, the easier it is to locate the optical center of the lenses.

The larger the lens the easier lt is to maintain the optical axis which is required - in making special lenses for people with particular eye problems, e g., for those persons with astigmatism.

Another advantage of the ~Z4~L 1 preferred soft lenses of the instant lnvention is that the instant preferred soft lenses have a softness similar to HEMA len~e~ but in addltlon, and most importantly, are more oxygen permeable, i.e.

are capable of transportlng more oxygen. HEMA lenses are not oxygen permeab~e or capable of transporting oxygen to a degree necessary to meet all the requ~rements o~ the human cornea.

The following examples are illustrative only and should not be construed as llmiting the invention. A11 parts and percents referred to herein are on a weight basls and all viscosities measured at 25C. unless otherwise specified.

EXAMPLE 1 557 g of 1,3-bls(4 hydroxybutyl) tetramethyl disiloxane~ 634 g of dry pyridine and 2 liters of hexane are charged to a 5 liter reaction flask equipped with a mechanical stirrer and drying tube.

The mixkure is chilled to 0C and then 836 g of methacryloyl chloride is added drop wise.

The mixture is agitated continuously overnight.

The reaction solution is extracted consecutively with 10% water solutions of HCl and NH3 in order t~ remove excess reagents and pyridine hydrochloride.

The resulting solution o~ the product in hexane is dried with anhydrous MgS04, filtered, and solvent removed at reduced pressure.

About 459 g (55% yield) of 1,3-bis(4~methacryloxy butyl) tetramethyl disiloxane is collected.

The structure is confirmed by infrared spectra~ proton magnetic resonance spectra and elemental analysis. IR spectra shows no intense hydroxyl band between 3100 and 3600 cm~l but does show strong methacrylate absorptions at 1640 and 1720 cm~l. PMR spectra agreed with the proposed structure:

~Z~ 1 ~ H2 ~ ~ CH2 ~CN5 ~ CH6 ~ 0 C = CH H~ CH3 _ _ 2 1,3-bis(4-methacryloxy butyl) tetramethyl disiloxane.

Proton ~Integrated Area Multiplicit~ Hl 7.05 1 singlet H2 6.50 1 singlet H 3 00 3 singlet H4 5.15 : 2 : triplet H5 2.7 4 multiplet H6 1.65 2 triplet H7 1.20 6 singlet Elemental analysis gave 13.6% Si (calc. 13.5~), 58.1p C (calc. 57.9%, and 9.4%H (calc. 9.2%). The product was a clear, colorless, fragrant fluid.

. EXANPLE 2 The fluid product of Example 1 is placed between glass plates with 0.2% benzoin methyl ether and irradiated with UV light at room temperature. A colorless, optically clear, hard9 ~2~ 1 highly crosslinked film is obtained- The ~ollowing is a represen tation of the cross-linked polymer.

~ (three dimensional network) CH2 bH?

CH3-C-8-O-CH2~CH2~2CH2-Si-O-$i-CH2~CH2~2CH2-O-~ ¦-CH3 CH3 CH3 CH2 2 CH3-c-~-o-cH2~cH2~2cH2-si-o-si-cH2~cH2~2cH2-o~-c-cH3 ¦ CH3 CH3 2 ICH2 1 2 lH2 ~ CH3-~-g-~^~ EXAMPLE 4 489.75 g of octamethylcyclotetrasiloxane and 10.25 g o~ 1, 3 bis(4-methacryloxybutyl) tetramethyl disiloxane are charged into a reaction vessel equipped with a mechanical stirrer. About 25 g of Fullerls Earth and 1.35 ml of conc. H2S04 are mixed and added to the vessel with continuous stirring while bubbling dry N2 through the reaction mixture. The charge is warmed to 60C and stirred for two days~ at which time the viscous fluid is neutralized with Na2C03, diluted with hexanes, and filtered. The hexanes/monomer solutlon is washed with water, dried with MgS04 (anhydrous) and -24 2~ 1 solvent removed at reduced pressure.

Lo~ molecular weight unreacted cyclic slloxanes are removed by heating the monomer to 110C at 0.2 mm Hg in a rotary evaporator.

The product obtained is an odorless, colorless, clear ~luid of 8.5 stokes viscosity measured in Gardner Viscosity tubes.

The monomer comprised about 260 repeating Me2SiO units.

Fluid collected during the devolatilizing Or the product shows no methacrylate absorptions in IR spectra and could not be cured.

IR spectra of the monomer shows a slight methacrylate absorption and broad siloxane absorptions between 1000 and 1100 cm~l, indicative of linear poly(dimethyl siloxanes) with the following formula: - \ H3 7H3 IH3 1 3 ~ 3 ll 2~ 2~2 2 b si c _ 7i CH2~CH2~2CH2- o ~ ~ CH2 H3 ~ H3 ~ 50 CH3 H2 EXAMPLE 5 Films of the fluid product of Example 4 are cast between glass plates by adding 0.2% bis(isobutyl) peroxy dicarbonate to the monomer and heating ~or 1/2 hour at 40C, V 2 and 60C and 1/4 hr.

at 80C.

The glass plates are separated.

The films are then kept at 80C for 15 minutesO Colorless optically clear, odorless, elastic and strong films are obtained such as represented by the three dimensional network polymer below.

The following physical properties are measured on an Instron tester ASTM D1708, no conditioning, using standard "dog bone" samples cut from 0.2 mm thick films.

The speed is 0.25 inches per minute.

This test is used on all the 3 Examples where tensile strength, modulus and elongation are ~easured.

~r / 8~ 1 (three dimensional network) ¦H2 CH3 /H3 CH3 ~ lH2 CH3-i- -0-CH2~cH2~2cH2 7 si~ CH2~CH2~2CH2-0~ -C-CH3 CH3 ~H~ 60H3 CH2 CH2 ~ IH3 ~ H ~ IH3 CQ ~ 3 CH24CH2~2cH2-li-ot~ -cH2~cH2~2cH2-o~ ( ~-CH3 3 \~ ~/260 3 CH2 CH2 1 I :

2 IH2 ~ CH3-~-C-0~~- Tensile strength 150 g/mm/mm2 Tensile modulus 72 g~mm/mm2 Elongation ~77% EXAMPLE 6 The fluid product o~ Example 4 together with 0 2% di(sec~butyl~peroxydicarbonate is placed in a suitable contact lens spin casting mold and spin cast under polymerizable conditions to a con~act lens -26 .

1 such as taught in U. S. patent 3,403,429.

The lens is optically clear? e~astic and strong.

EXAMPLE 7 About 97.3 g of octamethyl cyclotetrasiloxane, 2.7 g o~ 193-bis(4-mehacryloxybutyl) tetramethyl disiloxane and o.6 ml o~ tri~luoromethyl sulfonic acid are charged to a pressure bottle, sealed and shaken ror 24 hours.

The viscous monomer fluid obtained is neutralized with sodium carbonate and diluted with hexanes.

The monomer/hexanes solution is washed with water, dried with anhydrous MgS04 and the solvent removed at reduced pressure.

Volatiles are removed from the monomer at 0.2 mm Hg and 110C using a wiped film still.

High pressure gel permeation chromatography of the product shQws essentially total removal of low molecular weight volatile material.

The product is a colorless, clearg odorless fluid of 4.4 stokes viscosity measuring in Gardner vis cosity tubes.

The polymer below comprises about 200 repeating ~e2SiO units. IR spectra are similar to those taken in Example 4.

~ (three dimensional network) CH3-C-C-0-CH2~CH2~2CH2-Si-0 ~ i ~ Si-CH2~CH2~2CH2-0-C-C-CH3 ~ CH3 H CH3 CH3-C-C-0-CH2~CH2~2CH2-Si 0 ~i ~rli-CH2~CH2~2CH -~C~c~cH3 ~ CH3 H CH3 Cl H2 CH2 lH2 lH2 8~ 1 EXAMPLE 8 Films are made from the viscous fluid product of Example 7 using procedures simllar to Exarnple 5.

The ~ilms are tested, ASTM D1708, obtaining the following results:

Tensile strength 159 g/mm/mm2 Tensile modulus 104 g/mm/mm2 Elongatlon 151% EXAMPLE 9 The viscous fluid product produced in Example 7 is mixed with 2.0% benzoin butyl ether.

About 30 ~1 of the mixture is placed in a spinning contact lens mold under N2 atmosphere.

After 20 minutes irradiation with W light, a cured contact lens is obtained.

The lens formed is optically clear, elastic and strong.

XAMPLE 10 23 Ten (10) parts of allylmethacrylate monomer and four ten~hs (0.4~ of a part of t-butyl peroctoate are added to ninety (90) parts of the fluid product obtained in Example 4.

The reactlon mixture i~ placed into a casting cell which is then placed into an 80C oven for half an hour.

The temperature is therea~ter raised to lOQC and maintained at 100C for one hour.

An optically clear film is removed ~rom the cell and kept at 80C for 15 mlnutes.

The above is repeated by reacting the product of Example 4 with several other monomers as shown in Table I.

The percent 3 shown in Table I is the percent of co-monomer used.

The -23 29L8 .~ - 1 properties Or the copolymers are outlined in Table I.

As illustrated in Table I, it is one purpose of the instant invention to increase the tensile strength and elongation while retaining sur~icient oxygen transportability.

One problem with the prior art silicone polymers is that these polymers are not very strong and have poor tear strength and poor tensile strength.

One of the problems with the PHEMA ~control) is that contact lenses made ~rom this material do not have the necesaary oxygen transport; ing properties to meet all the requirements of the human cornea.

As mentioned, the oxygen requirement of the human cornea is about 2 x 10~6 cm3/ (sec. cm2 atm).

Table I illustrates the effect the instant co-monomers have on the strength of the polymers of the ; ~ instant invention.

There is an improvement in tensile strength with the use of the instant monomers.

In the case of modulus, it would be most preferred if the -~ modulus is below 300 in order to obtain a soft contact lens.

Therefore, generally the lower the modulus the so~ter the contact lens.

As to elongation, it is generally preferred tha~ e-ongation be as high as possible.

As to oxygen transport~ it is desirable that this rate be maximized.

This rate should be greater than the rate of oxygen required by the h~nan cornea.

The tensile strength test~ modulus test and elongation test are measured, as mentioned, on an Instron Tester ASTM D 1708 - using standard "dog bone" sarnples cut from O.2 mm thick films.

There is no conditioning and the speed is 0.25 inches per minute.

4~1~ 1 The Oxygen Transport Ra~e was determined by the following technique.

This test is measuring the oxygen permeability of a material while it is wet with water.

This is an attempt to closely reproduce the ~ame conditions which exist in the human eye when fitted with a contact lens.

Two chambers ~llled with water at 32C are connected together by a common passageway over which is placed the material to be tested.

Nitrogen-purged water is pumped into both chambers until the oxygen concentration is very low (~O.04 ppm).

Then air water (oxygen concentration~8 ppm~ is introduced into the lower chamber.

There is lvcated in the upper chamber an oxygen sensing electrode which measures thé diffusion of oxygen from the lower chamber through the membrane being tested and into the upper chamber.

This measures apparent oxygen transport rate of the material covering the passageway between the two chambers.

TABLE I Approximate Tensile*Apparent 2 Strength2 Modulus 2 Elongation Transport ~ _ (g/mm/mm ) (g/mm/mm ) (Percentage; Rate PHEMA _ _ 40 _ 40 150 4 x 10-7 Allyl methacrylate 10~ = 71 1~ ~ 62 x 10Butoxyethyl methacrvlate 10% 26 42 100 50 x 10-7 Butoxyethyl _ _ _ _ methac,ylate _ 30% 31 - - -- 38 _ 136 Cyclohexyl -7 ~ 70_ 75 131 56_ x 10 7 Ethyl methacrylate 10~ ~7 _ - ~0 13c 5I x 10 Methyl 00 90 _ 145 Ethyl hexyl _crylate 10% 50 73 110 54 x 10-7 Ethyl hexyl acrylate_ _ 30% 41 _ 69 _ 105 _ _ n bu acrylate10% _ 49 79 110 n bu acrylate10%% 5l -78 ~ 116 58 x_10bu acrylate30% 37 O 2 * h?parent Oxygen Transport Rate = cm (2) sec~cm'-atm .

34 1 EXAMPLE 11 58.3 ~ o~ 1,3-bis(4-methacryloxybutyl) tetramethyl dis~loxane, 41.7 g of octamethyl cyclotetrasiloxane, 1 ml concentrated H2S04 and 2 gm of Fuller's earth are charged into a pressure flask.

After two days equilibration the mixture is neutralized with Na2C03~ filtered, diluted with hexanes~ washed with water, dried, and the solvenk removed at reduced pressue The monomer product as illustrated below was a colorless~ odorless fluid with low viscosity as measured ; in Gardner Viscosity tubes.

10 g of monomer product is mixed with O.l wt. % benzoin methyl ether and 0.1 wt % azobis(isobutyronitrile).

The initiator-monomer solution ls poured into button molds and cured for 20 minutes under W light in a nitrogen atmosphere and therea~ter followed by 30 minutes at 80C ln alr.

The buttons are optic~lly clear, colorless~ hard and tough.

Contact lenses are lathed from these buttons- The following is the formula for khe above monomer:

CH3-CI-C-O-CH2~CH2~2CH2-Si- ~ 1 Si-CH2~CH2~2CH2-0-C-CI-CH3 CH2 CH3 H CH3 H2 ~EXAMPLE 12 ~5 7 g of the monomer product produced in Example 11 and 3 g of N-vinylpyrrolidone are mixed wîth 0.1 wt. % benzoin methyl ether and 0.1 wt. % azobis~isobutyronitrile)~ The initiator-monomer-comonomer solution is cured as described in 4~1~ . .

1 Example 11.

The copolymer buttons obtained are optically clear, -~ colorless, hard and tough.

The lathing of the buttons to ; contact lenses is substantially easier than the lathing of Example 11 buttons.

' EXAMPLE 13 30% tetrahydrofurfuryl methacrylate ~TFM) is copolymerized with 70% monomer of Example 11 in suitable molds.

The but~ons obtained are optioally clear, colorless~ hard and tough.

The TFM copolymer buttons are lathe cut into contact lenses.

EXAMPLE 14 99.3 g of octamethyl cyclotetrasiloxane, 0.7 g of 1~3bis(4-methacryloxybutyl) tetramethyl disiloxane, and 0.3 ml of trifluoromethyl sulphonlc acid are charged to a pressure bottle.

; The bottle is sealed and shaken for five days.

The monomer fluid obtained is neutralized with sodium carbonate and diluted with hexanes and filtered.

The monomer/hexanes solution is washed with water, dried over MgS04 and the solvenk removed at reduced pressure.

Volatiles are removed from the prepolymer at 0.2 mm Hg pressure and llO~C.

High pressure gel permeation chromatography of the product shows all low molecular weight volatile material is removed.

The product is a colorless~ clear~ odorless fluid of very high viscosity with about 800 repeating Me2Si~ units.

The following is a formula for the above monomer.

2~ 1 CH3 ~CH \ CH CH3_e_C_o-CH24CH2~2cH2-si-$5~ -si-cH2~cH2~2cH2-o~ c~I3 CH2 3 ~ ~ 00 3 H2 EXAMPLE 15 _ _ . Films are made ~rom the viscous ~luid product of Example 14 using procedures similar to ~xample 50 The films are tested giving the following results.

The following is a representation of the cross linked polymer.

(three dimensional network) ~ CH2-C-C-O-CH2~C~2~2CH2-S~ Si-CH2~C112~2cH2_o_c_c_cH3 3 OG 3 . I . I - CH2 C~2 CH ~ CH3 ~ H ~ CtH3 ~ ~ 2 C ~-CH2~CH2~2CH2-Si-OtSi-! li CH2~CH2~2 2 f 3 ¦ CH3 ~H~ oCoH3 CH2 fH2 fH2 fH2 ~ CH -C-~-O~ Tensile strength 34 g/mm/mm2 Tensile modulus 38 g/mm/mm ~ Elongation 208~ 2~ 1 EXAMPLE_16 ; Tetramethyl ammonium silanolate i5 prepared using the method of Gilbert and Kantor (J.

Poly.

Sci., 40, pp 35 58, (1959), Transient Catalyst for the Polymerization of Organosiloxanes)O 13 g of octaphenyl cyclotetrasiloxane, 92.4 g o~ octamethyl cyclotetrasiloxane, and 2~7 g o~ 1,3-bis(4-methacryloxybutyl) tetramethyl disiloxane are charged to a 500 ml 4-neck round bottom ~lask fitted with a drying tubel an N2 gas inlet and a mechanical stirrer.

The mixture is heated to 120 C and 1/2 ml of the base catalyst added.

The temperature is increased to 130C over the next 15 minutes and is held there for 10 minutes followed by cooling to room temperature.

The - viscous fluid product is diluted with hexanes, washed with acidic water (1% HCi), twice with water alone, dried over MgS04 5 and solvent removed at reduced pressure.

The product is siloxane monomer consisting of 5 mole % phenyl substituted silicone and 95 mole % methyl substituted silicone.

An in~rared spectrum of the monomer produc~ shows sharp weak absorptions at 700~ 1430, 1590 ; 20 and 3050 cm~l and a shoulder on the broad Si-O-Si absorption at 1125 cm 1.

These are characteristic of phenyl and silicone phenyl groups.

The product is colorless, transparent, odorless, and viscous.

The viscosity ls 17 stokes as measured in the Gardner Viscosity tubes.

It is cast into elastic~ transparent films using procedures similar to Example 5