CA1231215A - Method for the preparation of hydrophilic gels by monomer casting - Google Patents

Method for the preparation of hydrophilic gels by monomer casting

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Publication number
CA1231215A
CA1231215A CA000453495A CA453495A CA1231215A CA 1231215 A CA1231215 A CA 1231215A CA 000453495 A CA000453495 A CA 000453495A CA 453495 A CA453495 A CA 453495A CA 1231215 A CA1231215 A CA 1231215A
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CA
Canada
Prior art keywords
process according
hydrophilic
surface active
active agent
mold
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
CA000453495A
Other languages
French (fr)
Inventor
Otto Wichterle
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Czech Academy of Sciences CAS
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Czech Academy of Sciences CAS
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Publication date
Application filed by Czech Academy of Sciences CAS filed Critical Czech Academy of Sciences CAS
Application granted granted Critical
Publication of CA1231215A publication Critical patent/CA1231215A/en
Expired legal-status Critical Current

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Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29CSHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C33/00Moulds or cores; Details thereof or accessories therefor
    • B29C33/56Coatings, e.g. enameled or galvanised; Releasing, lubricating or separating agents
    • B29C33/60Releasing, lubricating or separating agents
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29DPRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
    • B29D11/00Producing optical elements, e.g. lenses or prisms
    • B29D11/00009Production of simple or compound lenses
    • B29D11/00038Production of contact lenses
    • B29D11/00125Auxiliary operations, e.g. removing oxygen from the mould, conveying moulds from a storage to the production line in an inert atmosphere
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29CSHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C41/00Shaping by coating a mould, core or other substrate, i.e. by depositing material and stripping-off the shaped article; Apparatus therefor
    • B29C41/02Shaping by coating a mould, core or other substrate, i.e. by depositing material and stripping-off the shaped article; Apparatus therefor for making articles of definite length, i.e. discrete articles
    • B29C41/04Rotational or centrifugal casting, i.e. coating the inside of a mould by rotating the mould
    • B29C41/042Rotational or centrifugal casting, i.e. coating the inside of a mould by rotating the mould by rotating a mould around its axis of symmetry
    • B29C41/045Rotational or centrifugal casting, i.e. coating the inside of a mould by rotating the mould by rotating a mould around its axis of symmetry the axis being placed vertically, e.g. spin casting
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29KINDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2033/00Use of polymers of unsaturated acids or derivatives thereof as moulding material
    • B29K2033/04Polymers of esters
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29KINDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2823/00Use of polyalkenes or derivatives thereof as mould material
    • B29K2823/10Polymers of propylene
    • B29K2823/12PP, i.e. polypropylene
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29LINDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
    • B29L2011/00Optical elements, e.g. lenses, prisms
    • B29L2011/0016Lenses
    • B29L2011/0041Contact lenses
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10STECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S525/00Synthetic resins or natural rubbers -- part of the class 520 series
    • Y10S525/937Utility as body contact e.g. implant, contact lens or I.U.D.

Abstract

METHOD FOR THE PREPARATION OF
HYDROPHILIC GELS BY MONOMER CASTING

ABSTRACT OF THE DISCLOSURE

Hydrogels, e.g. hydrogel contact lens are prepared by casting, preferably spin casting, hydrophilic gels in a plastic mold, preferably polypropylene in the presence of a surface active agent.

Description

1~3~ NPD- 14 2 7 METHOD FOR THY PREPARATION OF
HYDR~PHILIC OE US BY MONOMER COSTING

BACRGROUND OF THE INVENTION

The present invention relates to a method for the preparation of a hydrophilic gel by monomer casting a hydrophilic monomer in a plastic mold employing a surface active agent in the monomer containing mixture employed.
Monomer casting of hydrophilic gels, i.e.
of lightly cross-linked copolymers of hydrophilic monomers, has indisputable advantages in comparison to the manufacturing of shaped articles by mechanical processing or nonswollen gels and their subsequent swelling. When glass casting molds were used, it was possible to obtain castings with a perfect surface. However, as soon as casting models made of plastics began to be applied, particularly the molds made from polymeric olefins, e.g~
polypropylene, microscopical surface defects often occurred which caused, for example, a weak gray turbidity of cast contact lenses. The microscopical investigation of castings and casting molds revealed that minute parts of gel were torn from the surface ox the casting and adhered on the surface of mold.
Most probably, grafting of the polymerizing gel on the pvlymer of the creating mold occurred The surface of a mold made from a crystalline hydro-carbon was affected by grating above all in the places of amorphous areas of the olefin polymer which formed palisade structures on the mold surface and a replica of which was distinguished microscopically on the torn-out parts of the gel.
To prevent these defects, it has been recommended to ~,~

L2~L~

carry out the polymeriæation at a higher temperature e.g. at 110-135C. Though this defect was removed in this way, another problem occurred because a spontaneOus deformation of the molds took place at a temperature above the second-order transition and near the melting temperature of the olefin polymer. This caused serious defects, above all in the optics of cast contact lenses.

SUMMERY OF THE INVENTION

It has now been found that these problems can be solved by including in the hydrophilic monomer composition which is to be cast in a plastic mold a surface active agent which contains in addition to a hydrophobic group predominantly or completely hydrocarbon usually with at least six carbon atoms, preferably a hydrocarbon chain, an ionizable group or a strongly hydrophilic non-ionized group. Preerably 0 1 to 3 weight % of the monomer mixture is the surface active agent. After polymerization is complete and the object made of the hydrophilic gel removed from the mold the surface active agent can be readily washed out from the hydrophilic gel with a solvent, e.g. water or a mixture of water and a water-miscible solvent, e.g.
aqueous alcohol or aqueous isopropyl alcohol.
Apparently the surface active agent in the monomer mixture is adsorbed at the interface between the plastic mold, e.g. a polypropylene mold, and the strongly polar monomer mixture and acts as an inhibitor to grafting of the polymerizing monomers to the plastic mold.
While the mold is preferably made of polypropylene the process of the invention can be ~LZ3~

used when polymerizing hydrophilic monomers in molds made of other plastics, e.g. other olefin polymers such as whose made of polyethylene, ethylene-propylene copolymer, polyamylene, etc.
While the invention is preferably employed in the manufacture of cast contact lens, especially spin cast (i.e. centrifugally cast) contact lens it is also suitable for preparing other cast hydrophilic gel (hydrogel) objects, e.g. medical devices such as artificial heart valve substitutes, diaphragms and catheters as well as cast articles for non-medical uses, c artificial flower parts, containers for trapped enzymes or fragrances, etc.
Detergents, soaps, various wetting agents, and the like, are advantageously used as the surface active agents. Generally, the compounds, which reduce the surface tension of water to less than one half its normal value even at dilution 1:1000, are preferred.
For example, the following surface active compounds can be used:

1. A salt of triethanolamine and alkylbenzenesulfonic acid, where the alkyl has 12 to 18 carbon atoms, e.g.
triethanolamine salt of dodecyl-benzenesul~onic acid or the corresponding triethanolamine salt with a mixture of alkylbenzenesul~onic acids having 12 to 18 carbon atoms in the alkyl group), ~L~3~2~
2. a condensation product of palm-oil fatty acids with diethylene glycol and formaldehyde,
3. an addition product of an alkylphenol with oxirane (ethylene oxide) e.g.
p-nonylphenol-ethylene oxide having 20 units of ethylene oxide,
4. sodium oleate, sodium stearate, potassium oleate,
5. triethanolammonium caproate.
The particular surface active agent employed is not particularly critical so long as it has the charac-teristics pointed out above. Thus there can be used any of the surfactants set forth in Kirk-Othmer, Encyclopedia of Chemical Technology, second edition, Vol. 19 pages 507-593 which meet the abovementioned characteristics.
Attention is directed to the discussion in Kirk-Othmer as to ways of controlling solubility and surface activity.
The polymerization conditions can be varied over a wide range as is well known in the art. Separation of the gel casting from the mold can be effected by con-ventional techniques.
As indicated above the present invention is particularly useful in centrifugally, polymerization casting of axially symmetrical objects, such as, e.g.
hydrophilic gel lenses, artificial heart valve ~L~3~ 5 substitutes, etc. As is known in the art such centrifugal casting can be preformed by several techniques.
One such technique utilizes equipment wherein each rotatin9 mold containing the polymeri-zation reactants in the cavity thereof is adapted to rotate around their vertical axis. Rotation of each mold at a specifically determined speed creates a centrifugal force which causes the liquid reactants in the mold to generally assure the shape of the cavity of the mold that is contacted by the reactants. The molds can be grouped in linear array or alternatively can be assembled in carousel arrangement and individually rotated. This technique of operation along with various polymeri-zable compositions that can be used in the spin casting of various objects are disclosed in U.S.
Patent 3,560,545 issued on May 2, 1972.

In another technique a rotatable polymeri-zation tube is used which is adapted to receive a plurality of molds seated tightly to one another and each containing polymerizable reactants in the mold cavity. Thy molds are gravity fed into the upper end of the polymerization tube and free falls through the tube. The exit end of the tube is seated tightly on a revolving member which imparts rotation to the tube. An inert gas is fed upwards through the rotating polymerization tube about the free falling rotating molds.
The manufacture of the cast hydrophilic gels according to the invention comprises employing as the starting monomer system a hydrophilic monoolefinic monomer (i.e. a monoethylenically ;

3~2~

unsaturated monomer), a polyolefinic (preferably diolefinic) monomer (e.g. a polyethylenically unsaturated compound which functions as a cross-linking agent) in an amount to render the hydrophilic gel formed water insoluble but insufficient to destroy the hydrophilic properties, and the surface active agent, preferably in an amount of 0.1 to 3 weight % of the composition.
Obviously mixtures of hydrophilic monoolefinic monomers can be used as well as mixtures of cross-linking agents can be used. Also there can be included other monomers which are copolymerizable with the hydrophilic monomer so long as they are not used in an amount to destroy the requisite hydrophilic gel properties of the cast product.
Conventional solvents can also be presented.
The medium comprising the reactants is normally liquid and in the event centrifugal casting is employed should be capable of forming the desired shaped article during the centrifugal casting operation. The article may be opaque, translucent or transparent depending on the ultimate use of the cast article formed. For instance, it is not generally a necessity that diaphragms and artificial heart valve substitutes obtained by the practice of the invention be colorless and transparent. On the other hand as indicated above, for example, it is a requirement that soft hydrophilic contact lenses be fully transparent, of good optical quality, soft and resilient as well as possessing other necessary and desirable characteristics.
If the casting, e.g. centrifugal casting, is utilized in the manufacture of contact lenses they can be symmetrical or asymmetrical; low, medium, or high oxygen permeability or transport-~23~L2~LS

ability. By choosing suitably designed mold cavities orbottoms there can be obtained a wide variety of modified lens shapes, e.g., toric, bifocal, truncated and/or ballasted contact lenses. A wide variety of plastic materials or construction can be employed to fabricate the molds as indicated above. For the preparation of hydrophilic articles such as soft contact lenses a mold fabricated of a thermoplastic hydrocarbon material, prefer-ably polypropylene, is particularly suitable.
The surface of the mold can be pretreated or hydrophilized by known methods if desired.
The liquid cast object, e.g. contact lens, forming mixture as stated includes the surface active agent, hydrophilic monomer and cross-linking means.
Particular suitable components include hydrophilic monomers and polyolefinic monomers in an amount to form slightly or moderately cross-linked, three dimensional networks such as those disclosed in U.S. 3,822,089. Illustrative hydrophilic monomers include water soluble monoesters of an acrylic acid or methacrylic acid with an alcohol having an esterifiable hydroxyl group and at least one additional hydroxyl group such as the mono- and poly-alkylene glycol monoesters of methacrylic acid and acrylic acid, e.g., ethylene glycol monomethacrylate, 2S ethylene glycol monoacrylate, diethylene glycol mono-ethacrylate, diethylene glycol monoacrylate, propylene glycol monoethylate, dipropylene glycol monoacrylate, and the like; the N-alkyl and N,N-dialkyl substituted acryl-amides and methacrylamides such as N-methylacrylamide, N,N-dimethylacrylamide, N-methylmethacrylamide, N,N-dimethylmethacrylamide, ~L~3 and the like; N vinylpyrrolidone; the alkyl substituted N-vinyl pyrrolidones, e.g., methyl substituted N-vinylpyrrOlidone glycidyl met~acrylat~; glycidyl acrylate; the unsaturated amines; the alkoxy ethyl acrylates (e.g~
methoxyethylacrylate); mixtures thereof; and others known to the art.
As indicated above in the practice of the invention to manufacture hydrophilic gel objects, e.g. contact lenses, there can be included hydrophobic acrYlic esters, suitably lower alkyl acrylic esters, preferably wherein the alkyl moiety contains 1-5 carbon atoms, such as methyl acrylate or methacrylate~ ethyl acrylate or methacrylate, n-proPyl acrylate or methcrylate, isopropyl acrylate or methacrylate, isobutyl acrylate or methacrylate, n-butyl acrylate or methacrylate, amyl acrylate or mixtures thereof.
Other suitable monomers include the ethy-lenically unsatured monocarboxylic acid esters, in particular, the methacrylic and acrylic acid esters of siloxane monomers and polymers with/without a pendant hydroxyl group. These monomers are well documented in the contact lens art; see, for example, U.S. Pat. Nos. 4,139,548: 4,235,985;
4,152,508; 3,808,178; 4,139,692; 4,248,989; and 4,139,513.

Among the preferred monomeric mixtures are those which contain at least one alkylene glycol monoester of methacrylic acid, especially ethylene glycol monomethacrylate, and at least one cross-linking monomer such as the alkylene glycol diester .

~.2~2~

of methacrylic acid, especially ethylene glycol ~imethacrylate. Such mixtures may contain other polymerizable monomers, desirably in minor amounts such as N-vinylpyrrolidone, methyl methacrylate, acrylamide, glycidyl methacrylate, N methylacryl-amide, diethylene glycol monomethacrYlate, and others illustrated above.
As pointed out sure the above illustrated monomeric mixtures, including mixtures of hydro-phobic and hydrophilic reactants, erally include a minor proportion ox di- or higher polyfunctional (e.g. di or higher ethylenically unsaturated) polymerizable compound to cause cross-linking of the polymeric matrix as polymerization or curing proceeds. Examples of SUCK di- or higher polyfunc-tional species include: divinylbenzene, ethylene glycol diacrylate or methacrylate, propylene glycol diacrylate or methacrylate, and the acrylate or methacrylate esters of the following polyols:
triethanolamine, glycerol, pentaerythritol, butylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, mannitol, sorbitol and the like. Other cross-linking monomers can be illustrated by N,N-methylene-bis-acrylamide or methacrylamide, sulfonated divinylbenzene, and divinylsulfone.
Additional lens-forming materials, providing they form hydrophilic gels, which are suitable in the fabrication of contact lenses are illustrated by one or more of the following U.S.
Patents: 2,976,576; 3,220,960; 3,937,680;
3,g48,871; 3,949,021; 3,983,083; 3,988,274;
4,018,853; 3,875,211; 3,503,942; 3,532,679;
3,621,079; 3,639,524; 3,700,761; 3,721,657;
3,758,448; 3,772,235: 3,7~6,034; 3,803,093;

~23~

3,816,571; 3,940,207; 3,431,046; 3,542,~61;
4,055,378; 4,064,086; and 4,062,627.
The polymerization reaction can be carried out in bulk or with an inert solvent. Suitable solvents include water organic solvents such as water-soluble lower aliphatic monohydric alcohols, e.g~ ethyl alcohOl, isopropyl alcohol or methyl alcohol, as well as polyhydric alcohols, e.g., ethylene glycol~ propylene glycol, glycerol, diethylene glycol, dioxane, etc.; and mixtures thereof In general, the solvent comprises a minor amount of the reaction medium, i.e., less than about 50 weight percentO
Polymerization of the cast article, e.gO
lens-forming mixture may be carried out with free radical catalysts and~or initiators of the type in common use in vinyl polymerization. Such catalyst species can include the organic peroxides e.g.
benzoyl peroxide, the alkyl percarbonates, e.g.
ethyl percarbonate, hydroperoxides, e.g.
t-butylhydroperoxide, and inorganic materials such as hydrogen peroxide and ammonium, sodium, or potassium persulfate. Polymerization temperatures can vary from about 20C, and lower, to about 100Ct and higher.
Polymerization of the moncmer material can also be effected using, for example, radiation (U.V., X-ray, mlcrowave, or other well-known forms of radiation) (which may cause crosslinkiny of ye forming polymerizate) with/
without the presence of well-known initiator(s) and/or catalyst(s).
The shape of a lens blank or other article formed by the casting procedure may be controlled not only by the size and shape of the mold, but also by the amount and nature of the components comprising the lens-forming mixture, by the ~3~

rotational speed of the mold during polymerization, by the position of the axis of rotation of the mold relative to the direction of gravity, and the like.
Tilting the axis of rotation or when the axis of rotation does not pass through the optical center of the (forming) lens, a prism component can be added to the lens In the fabrication of contact lenses, the lens-forming material is placed in the mold cavity having an optical concave surface wetted by said material, and then for example can be fed one at a time into the inlet end of a polymerization column.
The molds can have a pretreated optical surface to increase its hydrophilicity or wettability in a manner well-known in the art. The speed of rotation of the column (if used) and the molds is then adjusted to cause and~or maintain radially outward displacement of the lens-forming mixture to a predetermined lens configuration which when subjected to the polymerization conditions employed in the column will form the desired shaped contact lens. Rotational speed of, for example, 300 r.p.m., and lower to 600 r.p.m., and higher, can be conveniently used. The precise rotational speed to employ in the operation is, of course, well within the skill of the artisan. Factors to be considered include the type and concentration of the components comprising the lens-forming material employed, the operative conditions of choice, the type and concentration of catalyst, initiator, and/or radiation energy sourcer and factors discussed previously and readily apparent to the artisan.
The compositiOn employed can comprise, consist essentially of or consist of the essential materials set forth above and the steps of the ~23~

process can comprise, consist essentially of or consists of the stated steps.
Unless otherwise indicated all warts and percentages are by weight DETAILED DESCRIPTION

A safe separation of a hydrophilic gel casting from a mold is achieved according to the invention even in low-temperature polymerization processes, e.g. in photopolymerization.
The invention is further illustrated by the following examples of performance.

Example 1 A mixture of 100 parts by weight of 2-hydroxyethyl methacrylate, 0.9 parts triethylene glYcol dimethacrylate, 1% of (1) a salt of triethanolamine and a 12-18 carbon atoms alkylbenzenesulfonic acid, (2) a condensation product of palm oil fatty acids, diethylene glycol and formaldehyde and (3) an addition product of an alkylphenol with ethylene oxide (having - carbon atoms in the alkyl group and - ethylene oxide units) and 0.4 part of benzoin ethyl ether (polymerization initiator) was polymerized in a closed mold for casting contact lenses, the mold being made from low-pressure polyethylene, at 25C under irradiation with a 100-W mercury lamp from the distance of 100 mm through a filter made from a 3 mm thick dethermal glass. After 10 minutes! the mold was opened and a xerogel contact lens was removed and subjected to the usual processing by mechanical adaptation of edges, swelling with water washing with 50% aqueous isopropyl alcohol, and finally with 231;;~

physioloqical saline. PreEerably clear lenses were obtained in this way.

Example 2 A mixture containing 70 parts of 2-hydroxyethyl methacrylatet 29 parts 2-(2-hydroxy-ethsxy)ethyl methacrYlate~ 0O3 parts ethylene dimethacrylate, 1 part of a 10% aqueous solution of ammonium peroxydisul~ate and 40 parts ox a lP6 glycerol solution of sodium oleate was employed for the manufacturin9 of contact lenses by centrifugal casting in polypropylene molds at a polymerization temperature of 75C. The castings were removed from the polypropylene molds by swelling in water, which lead to a spontaneous separation of the lenses from the molds. The lenses were further processed in the usual way with perfect results as in Example 1.

Example 3 -The procedure of Example 1 was repeated using a polypropylene mold and employing as the inhibiter of grafting a commercial preparation "Sampson U~IVERSA~ shampoo) produced by Druchener Prague. It is a brownish sirupy liquid and is added to the monomer mixture in on amount of 1%. The polymerization proceeds regularly even with higher additions of the surface active agent, eOg. 4~, but at the 4% level the lenses formed are slightly turbid in their bulk.
The composition of the Shampoo is as follows:
12~ of Abezon*(98% paste of the triethanolamine salt of C12-C18 alkylbenzene sulfonic acid produced by ~Spolek pro chemickou vyrobun, Usti nud Labem~

* trademarks ,, , ~L23~L2~

12% oÇ RDF-16 (the condensation product of coconut fatty acids and diethylene glycol with formaldehyde, 80% of active substancel; produced by "Tukove æavody", Lovosi~e~
5 ........ 1.5% of Siovasol*909 (the addition product of oxirane (ethylene oxide and alkylphenol); produced by "Chemicke zavody", Novaky o.9% of Syntron*(sodium ethylenediamine tetracetate); produced by "Luceben zavody", Rolin.
The balance is water and insert material.
IllustratiVe other polymerizable mixture to which 1% based on the total weight of the mixture of a surfactant, e.g. as set forth in Example 1, 2 or 3 above can be added to make a Wsoft~ contact lens by castinq in a mold of polypropylene or other polymeric hydrocarbon according to the invention include the hollowing:
;

: Composition A
2-hydroxyethyl methacrylate 84.6 parts ethylene glycol dimethacrylate 1.0 part benzoin methyl ether (initiator) 0.2 part glycerol 14.2 parts Composition B
2-hv~roxyethyl methacrylate 78 parts methacrylic acid 2 parts isopropyl percarbonate 0.4 part glycerol 19 parts ethylene glycol dimethacrylate 1.0 part * trademarks , .~

Composition C
2-hydroxyethyl methacrylate95 parts methyl methacrylate 5 parts benzoin methyl ether 0.2 part propylene glycol 10 parts ethylene glycol dimethacrylate 0.5 part

Claims (19)

WHAT IS CLAIMED IS:
1. In a process of preparing a hydrophilic gel article by monomer cast polymerization of a mixture containing a monoolefinic hydrophilic monomer in a plastic mold the improvement comprising including in the polymerizable monomer mixture a surface active agent in an amount effective to prevent grafting of the hydrophilic gel on the plastic mold.
2. A process according to claim 1 wherein the article is a hydrophilic contact lens.
3. A process according to claim 2 wherein the casting is centrifugal casting.
4. A process according to claim 1 wherein the casting is centrifugal casting.
5. A process according to claim 1 wherein the plastic mold is made of a hydrocarbon polymer.
6. A process according to claim 5 wherein the plastic mold is made of polyethylene or polypropylene.
7. A process according to claim 6 wherein there is employed up to 4 weight % of the surface active agent.
8. A process according to claim 7 wherein there is employed 0.1 to 3 weight % of the surface active agent.
9. A process according to claim 8 wherein the surface active agent has a hydrophobic predominantly hydrocarbon or completely hydrocarbon chain and either an ionizable group or a strongly hydrophilic nonionizable group.
10. A process according to claim 9 wherein the hydrophobic chain is a hydrocarbon chain having at least 6 carbon atoms.
11. A process according to claim 10 wherein the plastic mold is made of a hydrocarbon polymer.
12. A process according to claim 2 wherein the mold is made of a hydrocarbon polymer.
13. A process according to claim 12 wherein the mold is made of polyethylene or polypropylene.
14. A process according to claim 13 wherein there is employed 0.1 to 3 weight % of the surface active agent.
15. A process according to claim 14 wherein the surface active agent has at least 6 carbon atoms and either an nonionizable group or a strongly hydrophilic nonionizable group.
16. A process according to claim 12 wherein there is employed 0.1 to 3 weight % of the surface active agent and the surface active agent has at least 6 carbon atoms and either an ionizable group or a strongly hydrophilic nonionizable group.
17. A process according to claim 16 wherein the hydrophilic monomer is a mono or polyalkylene glycol monoester of acrylic acid or methacrylic acid.
18. A process according to claim 17 wherein the polymerizable mixture includes a di or higher polyfunctional monomer in an amount effective to form a cross-linked hydrophilic gel.
19. A process according to claim 18 wherein the cross-linking agent is an alkylene glycol or polyalkylene glycol diacrylate or dimethacrylate.
CA000453495A 1983-08-17 1984-05-03 Method for the preparation of hydrophilic gels by monomer casting Expired CA1231215A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CS836009A CS239282B1 (en) 1983-08-17 1983-08-17 Preparation method of objects made from hydrophilic gelsnamely contact lences by polymer casting
CSPV6009-83 1983-08-17

Publications (1)

Publication Number Publication Date
CA1231215A true CA1231215A (en) 1988-01-12

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Family Applications (1)

Application Number Title Priority Date Filing Date
CA000453495A Expired CA1231215A (en) 1983-08-17 1984-05-03 Method for the preparation of hydrophilic gels by monomer casting

Country Status (4)

Country Link
US (1) US4534916A (en)
CA (1) CA1231215A (en)
CS (1) CS239282B1 (en)
GB (1) GB2145028B (en)

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US4534916A (en) 1985-08-13
GB2145028A (en) 1985-03-20
CS239282B1 (en) 1986-01-16
GB2145028B (en) 1986-07-23
CS600983A1 (en) 1985-05-15

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