GB2196973A

GB2196973A - Hydrophilic copolymer and the method for producing thereof

Info

Publication number: GB2196973A
Application number: GB08713892A
Authority: GB
Inventors: Otto Wichterle; Jiri Vacik; Jiri Michalek; Zuzana Krcova; Jiri Vodnansky
Original assignee: Czech Academy of Sciences CAS
Current assignee: Czech Academy of Sciences CAS
Priority date: 1986-06-24
Filing date: 1987-06-15
Publication date: 1988-05-11
Anticipated expiration: 2007-06-15
Also published as: IT1205164B; FR2600658A1; IT8720985A0; FR2600658B1; GB2196973B; CA1293586C; CS257979B1; DE3720884A1; JPS6322811A; GB8713892D0; DE3720884C2

Description

1 1 GB 2 196 973A 1

SPECIFICATION

Hydrophilic copolymer and the method for producing thereof.

The invention pertains to a hydrophilic copolymer suitable above all for contact lenses and medical purposes and also to a method for its production.

Water-swellable elastomers with various equilibrium content of water are known and used for manufacturing of soft hydrophilic contact lenses and for a great variety of medical applications. In such applications where suit- able mechanical properties are emphasized and the content of water about 40 wt.% is sufficient, the polymers of 2-hydroxyethyl methacrylate (HEMA) proved excellent. However, a number of applications require highly swelling materials (e.g. the contact lenses for permanent wearing), often at a lower modulus of shear elasticity but a sufficient elongation. In spite of that, the hydrophilic polymers so far known have the mechanical properties at a high swelling insuitable to such extent, that they cannot be used. Therefore lightly crosslinked copolymers of the strongly hydrophilic N- vinylpyrrolidone with hydrophobic alkyl methacrylate were developed (Brit. Patent no.

1,514,810), which have better mechanical properties in combination with the high swelling. They however contain an undesirable portion of extractables.

Diethylene glycol methacrylate (2-(2-hydroxy- ethoxy)ethyl methacrylate), a homologue of 2hydroxyethyl methacrylate, gives a highly swelling polymer owing to its ether oxygen atom in the ester chain, which however has not suitable mechanical properties even in a crosslinked state and cannot be used for certain applications for this reason.

The above mentioned disadvantages are overcome in a hydrophilic copolymer according to the invention which is suitable above all for contact lenses and medical applications 110 and can be prepared by copolymerizing a monomer mixture containing 2-hydroxyethyl methacrylate (HEMA) and 2-(2-hydroxyethoxy) ethyl methacrylate (diethylene glycol metacryla te-DEGMA) in the amount of 90 to 99.99 115 wt.% with the free methacrylic acid or acrylic acid or with their sodium, potassium and am monium salts in the amount of 10 to 0.01 wt.% in the presence of radical initiators, whereas the content of 2-(2-hydroxyethoxy)ethyl methacrylate in the monomer mixture 2hydroxyethyl methacrylate-2-(2-hydroxyethoxy)ethyl methacrylate is from 0 to 50 wt.% and the entire monomer mixture contains 0.01 to 4 wt.% of a cross-linking agent which has at least two olefinic double bonds.

The crosslinking agent is advantageously chosen from a group comprising multifunctional esters or amides of acrylic acid or methacrylic acid.

The radical initiators are selected from a group comprising azo compounds, peroxides, peroxocarbonates, persulfates, photo-initiators based on benzoin ethers and their derivatives, and also initiation redox systems, advantageously persulfate- metabisulfite, persulfate-alkylamines, or benzoyl peroxide-alkylamines, in the preferable concentration of 0.01-3 wt.%, The copolymerization may be carried out in the presence of polar solvents, advantageously glycerol, glycols and their derivatives, water, dimethylformamide, dimethylsulfoxide, dimethylacetamide, diacetine, isopropanol, or their mixtures. The ratio of the solvent to the monomer mixture may range from 1:99 to 50:50 (wt.%).

If the free methacrylic acid or acrylic acid is used in the production of hydrophilic copolymer according to the invention, the ob- tained copolymer can be advantageously reconditioned in aqueous or alcoholic solutions of sodium, potassium or ammonium hydroxide, or of their salts with weak acids, followed by washing, advantageously with distilled water. In this way, the free carboxylic group is transferred to the sodium, potassium or ammonium salt which leads to an increased sok vation in the neighbourhood of these COOX groups (where X=Na, K, or NHj and an increase in the overall swelling capacity of polymer matrix.

If the copolymerization is carried out. in the absence of a polar solvent or a mixture of polar solvents, a bulk copolymer is obtained which is suitable above all for the applications requiring the subsequent mechanical working. However, some articles can be made also-directly by this copolymerization in bulk.

In the presence of the above said polar sol- vents as individuals or of their mixture, the copolymer with a suitably chosen content of the solvent is prepared which is suited for casting, e. g. the centrifugal casting of contact lenses. The used solvent, which prevented from the mechanical working in the first case, here favourably influences the swelling pressures appearing in the swelling of final article.

This makes possible, and in the production of high-swelling turned contact lenses even advantageous, to extract the solvent, or also water- soluble low-molecular weight portions, present in the crosslinked copolymer prepared in the presence of the above said polar sok vents with water and then dry the copolymer to a constant weight. The resulting xerogel is excellently suited for mechanical working. The drying can be then carried out advantageously in saturated steam above the glass-transition temperature T. of the prepared copolymer.

The advantage of this process, in comparison with the method for preparation of contact lenses from various types of xerogels used so far, consists not only in the possible perfect removal of low-molecular weight sub- stances by washing as stated above, but also 2 in attaining a more ordered structure with re spect to the internal stress of cross-links, which is retained during drying and gives the contact lenses produced from thus prepared xerogel with the polymer network without in ternal stress after reswelling owing to the or dered structure of cross-links, which is visible in polarized light. Also a high conversion of polymerized components is assured by this method of preparation in comparison to the xerogel material prepared by polymerization without solvent.

Another advantage of this process consists in the fact, that the glass transition tempera ture T. increases by about six degrees C with 80 each percent of monomer and low-molecular weight portion removed by washing and favourably affects the turning and polishing of the final shape of contact lens.

The drying of water-swelled prefabricated elements for turned contact lenses in superheated steam is advantageous, because the polymerization solvent, i.e. water, is removed from a three-dimensional structure under con- ditions of the perfect mobility of polymer chains and their side segments (i.e. above Tg of the copolymer), thus assuring a rapid removal of the solvent without damage of the three-dimensional structure at the retained ra- tio of outer dimensions and angles of the dried prefabricated element with respect to the swollen one at the given initial composition of polymerization mixture.

Copolymers of 2-hydroxyethyl methacrylate with diethylene glycol monomethacrylate and with sodium, potassium or ammonium methacrylate were prepared in the presence of diethylene glycol dimethacrylate and ethylene glycol climethacrylate, or in the presence of only one crosslinking component which may be an arbitrary diester of methacrylic acid or acrylic acid and the corresponding alkylene glycols if the starting monomers are completely freed of their own cliesters originated in their synthesis, or methylene-bis-acrylamide, ethylene-bis- methacrylamide, hexamethylenebis-methacrylamide, and others, or their combinations may be used as a crosslinking component in such a way, that always at least 3 components enter the polymerization, two of which contain one olefinic double bond and the third one is a crosslinking agent.

The invention is further illustrated in the examples of performance without limiting the scope of invention by any means.

Example 1 The mixture consisting of 99.7 wt.% of 2hydroxyethyl methacrylate (further only HEMA) and 0.3 wt.% of sodium methacrylate (further only NaMA) and containing 0. 3 wt.% of ethylene glycol climethacrylate was polymerized with 0.1 wt.% of diisopropyl peroxocarbonate related to the total amount of monomers for 16 hours at 60'C. The resulting material after GB2196973A 2 swelling contains 38 wt.% of water at the shear modulus of elasticity G=0. 305 MPa.

Example 2

A mixture consisting of 99.4 wt.% of HEMA and 0.6 wt.% of NaMA and containing 0.3 wt.% ethylene glycol climethacrylate was polymerized with 0.1 wt.% of diisopropyl peroxocarbonate related to the total amount of monomers for 16 hours at 60'C. The resulting material after swelling contains 40 wtA of water at G=0.315 MPa.

Example 3 A mixture consisting of 98.7 wt.% of HEMA and 1.3 wt.% of potassium methacrylate and containing 0.3 wt.% of ethylene glycol dimethacrylate was polymerized with 0.1 wt.% of diisopropyl peroxocarbonate related to the to- tal amount of monomers for 16 hours at 60'C. The resulting material after swelling contains 45 wt.% of water at G=0.325 MPa.

Example 4

A mixture consisting of 98.2 wt.% of HEMA and 1.8 wt.% of NaMA, and containing 0.3 wt.% of ethylene glycol climethacrylate was polymerized with 0.1 wt.% of diisopropyl peroxocarbonate related to the total amount of monomers for 16 hours at 60'C. The resulting material contains 48 wt.% of water after swelling at G=0.340 MPa.

Example 5

A mixture consisting of 97.5 wt.% o and 2.5 wt.% of potassium methacrylate and containing 0.3 wt.% of ethylene glycol dimethacrylate was polymerized with 0.1 wt.% of diisopropyl peroxocarbonate related to the to- tal amount of monomers for 16 hours at 60'C. The resulting material contains after swelling 50 wt.% of water at G=.0350 MPa.

Example 6

A mixture consisting of 97 wt.% of HEMA and 3 wt.% of NaMA and containing 0.3 wt.% of ethylene glycol dimethacrylate was polymerized with 0.1 wt.% of diisopropyl per oxocarbonate related to the total amount of monomers for 16 hours at 60'C. The resulting material contains after swelling 55 wt.% of water at G=0.361 MPa.

Example 7

A mixture consisting of 96 wt.% of HEMA and 4 wt.% of NaMA and containing 0.3 wt.% of ethylene glycol climethacrylate was polymerized with 0.1 wt.% of diisopropyl per oxocarbonate related to the total amount of monomers for 16 hours at 60'C. The resulting material contains after swelling 57 wt.% of water at G=0.372 MPa.

Example 8

A mixture consisting of 95 wt.% of HEMA 3 GB2196973A 3 and 5 wt.% of NaIVIA and containing 0.3 wt.% of ethylene glycol dimethacrylate was polymerized with 0.1 wtA of diisopropyl peroxocarbonate related to the total amount of monomers for 16 hours at 60'C. The resulting material contains after swelling 63 wt.% of water at G=0.380 MPa.

Example 9

A mixture consisting of 69.9 wt.% of HEIVIA, 30 wt.% of diethylene glycol monomethacrylate (further only DEGIVIA) and 0.1 wt.% of NaIVIA and containing 0.2 wt.% of ethylene glycol dimethacrylate was polymerized with 0.1 wt.% of diisopropyl peroxocarbonate related to the total amount of monomers for 16 hours at 60'C. The resulting material after swelling contains 46 wt.% of water at G=0.165 Wa.

Example 10 A mixture consisting of 69.75 wt.% of HEIVIA, 30 wt.% of diethylene glycol monomethacrylate (further only DEGIVIA) and 0.25 wt.% of NaMA and containing 0.2 wt.% of ethylene glycol dimethacrylate was polymerized with 0.1 wt.% of diisopropyl peroxocarbonate related to the total amount of monomers for 16 hours at 60'C. The resulting material contains after swelling 48 wt.% of water at G=0.170 Wa.

Example 11 A mixture consisting of 69.5 wt.% of HEIVIA, 30 wt.% of DEGIVIA and 0.5 wt.% of NaIVIA and containing 0.2 wt.% of ethylene glycol dimethacrylate and 0.1 wt.% of diethylene glycol dimethacrylate was polymerized with 0.1 wt.% of diisopropyl peroxocarbonate related to the total amount of monomers for 16 hours at 60'C. The resulting material contains after swelling 50 wt.% of water at G=0.170 Wa.

Example 12 A mixture consisting of 69.2 wt.% of HEIVIA, 30 wt.% of DEGIVIA and 0.8 wt.% of NaMA and containing 0.2 wt.% of ethylene glycol dimethacrylate and 0.1 wt.% of diethylene gly- col dimethacrylate was polymerized with 0.1 wt.% of diisopropyl peroxocarbonate related to the total amount of monomers for 16 hours at 60C. The resulting material after swelling contains 52 wt.% of water at G=0.180 Wa.

Example 13 A composition consisting of 69 wt.% of HEIVIA, 30 wt.% of DEGIVIA and 1 wt.% of NaMA and containing 0.2 wt.% of ethylene glycol dimethacrylate and 0.2 wt.% of diethy lene glycol dimethacrylate was polymerized with 0.1 wt.% of diisopropyl peroxocarbonate related to the total amount of Monomers for 16 hours at 60'C. The resulting material con130 tained after swelling 55 wt.% o f water at G=0.190 MPa.

Example 14

A mixture consisting of 98.7 wt.% of HEIVIA and 1.3 wt.% of NaIVIA and containing 0.5 wt.% of ethylene glycol dimethacrylate as a crosslinking agent was mixed in the amount of 90 wt.% with 10 wt.% of glycerol. The mix- ture was polymerized with 0.5 wt.% of benzoin ethyl ether related to the total amount of monomers for 15 minutes under UV radiation. The resulting material after swelling contains 47.8 wt.% of water at the shear modulus of elasticity G=0.283 MPa.

Example 15 A mixture consisting of 98.2 wt.% of HEIVIA and 1.8 wt.% of NaIVIA and containing 0.5 wt.% of ethylene glycol dimethacrylate was mixed in the amount of 90 wt.% with 10 wt.% of diacetine. The mixture-was polymerized with 0.5 wt.% of benzoin ethyl ether related to the total amount of monomers for 15 minutes under UV radiation. The resulting material after swelling contains 50.5 wt.% of water at G=0.290 Wa.

Example 16 1

A mixture consisting of 97.5 wt.% of HEIVIA and 2.5 wt.% of NaMA and containing 0.5 wt.% of ethylene glycol dimethacrylate was mixed in the amount of 90 wt.% with 10 wt.% of glycerol. The mixture was polymer- ized with 0.5 wt.% of benzoin ethyl ether related to the total amount of monomers for 15 min under UV radiation. The resulting material contains after swelling 52.4 wt.% of water at G=0.300 Wa.

Example 17 A mixture consisting of 97 wt.% of HEIVIA and 3 wt.% of NaMA and containing 0.5 wt.% of ethylene glycol dimethacrylate was mixed in the amount of 90 wt.% with 10 wt.% of glycerol. The mixture was polymerized with 0.5 wt. % of benzoin ethyl ether related to the total amount of monomers for 15 minutes under UV radiation. The resulting material contains after swelling 56.2 wt.% of water at G=0.309 Wa.

Example 18 A mixture consisting of 98.7 wt.% of HEIVIA and 1.3 wt.% of NaMA and containing 0.4 wt.% of hexamethylene-bis- acrylamide and 0.35 wt.% of methylene-bis-acrylamide was mixed in the amount of 80 wt.% with 20 wt.% of glycerol. The mixture was polymer- ized with 0.5 wt.% of benzoin ethyl ether related to the total amount of monomers for 15 minutes under UV radiation. The resulting material contains after swelling 49.0 wt.% of water at G=0.263 MPa.

1 4 Example 19 A mixture consisting of 98.2 wt.% of HEMA and 1.8 wt.% of NaMA and containing 0.5 wt.% of ethylene glycol dimethacrylate was mixed in the amount of 80 wt.% with 20 wt.% of glycerol. This mixture was polymerized with 0.5 wt.% of benzoin ethyl ether related to the total amount of monomers for 15 minutes under UV radiation. The resulting material contains after swelling 53 wt.% of water at G=0.273 MPa.

Example 20 A mixture consisting of 97.5 wt.% of HEMA and 2.5 wt.% of NaMA and containing 0.5 wt.% of ethylene glycol climethacrylate was mixed in the amount of 80 wtA with 20 wtA of glycerol. This mixture was polymerized with 0.5 wt.% of benzoin ethyl ether re- lated to the total amount of monomers for 15 minutes under UV radiation. The resulting material contains after swelling 54.7 wt.% of water at G=0. 291 MPa.

Example 21 A mixture consisting of 97 wt.% of HEMA and 3 wt.% of NaMA and containing 0.5 wt.% of ethylene glycol climethacrylate was mixed in the amount of 80 wt.% with 20 wt.% of glycerol. This mixture was polymerized with 0.5 wt.% of benzoin ethyl ether related to the total amount of monomers for 15 minutes under UV radiation. The resulting material contains after swelling 58.3 wt.% of water at G=0.302 MPa.

Example 22 A mixture consisting of 98.7 wt.% of HEMA and 1.3 wtA of potassium methacrylate and containing 0.5 wt.% of ethylene glycol dimethacrylate was mixed in the amount of 70 wt.% with 30 wt.% of glycerol. This mixture was polymerized with 0.5 wt.% of benzoin ethyl ether related to the total amount of monomers for 15 minutes under UV radiation. The resulting material contains after swelling 51.3 wt.% of water at G=0.223 MPa. The coefficients of linear expansion K,1.17 (for swelling in water) and Ks = 1. 11 (for swelling in physiological saline).

Example 23 A mixture consisting of 98.2 wt.% of HEMA and 1.8 wt.% of NaMA and containing 0.5 wt.% of ethylene glycol climethacrylate was mixed in the amount of 70 wt. % with 30 wt.% of glycerol. This mixture was polymerized with 0.5 wt.% of benzoin ethyl ether related to the total amount of monomers for 15 minutes under UV radiation. The resulting material contains after swelling 56.5 wt.% of water at G=0.235 MPa, K,=1.21, and K=1.13.

Example 24

GB 2 196 973A 4 A mixture consisting of 97.5 wt.% of HEMA and 2.5 wt.% of NaMA and containing 0.5 wt.% of ethylene glycol climethacrylate was mixed in the amount of 70 wt.% with 30 wtA of glycerol. This mixture was polymerized with 0.5 wt.% of benzoin ethyl ether related to the total amount of monomers for 15 minutes under UV radiation. The resulting material contains after swelling 59.5 wt.% of water at G=0.251 MPa, Kw= 1.25 and K,= 1. 16.

Example 25 A mixture consisting of 97 wt.% of HEMA and 3 wt.% of NaMA and containing 0.5 wt.% of ethylene glycol climethacrylate was mixed in the amount of 70 wt.% with 30 wt.% of glycerol. This mixture was polymerized with 0.5 wt.% of benzoin ethyl ether re- lated to the total amount of monomers for 15 minutes under UV radiation. The resulting material contains after swelling 61.9 wt.% of water at G=0. 26 1, Kw= 1.29 and K,= 1. 18.

Example 26 A mixture consisting of 98.7 wt.% of HEMA and 1.3 wtA of NaMA and containing 0.5 wt.% of ethylene glycol climethacrylate was mixed in the amount of 60 wt.% with 40 wt.% of glycerol. The mixture was polymerized with 0.5 wt.% of benzoin ethyl ether related to the total amount of monomers for 15 minutes under UV radiation. The resulting material contains after swelling 53 wt.% of water at G=0.190 MPa, K,=1.12 and K,=1.06.

Example 27 A mixture consisting of 98.2 wt.% of HEMA and 1.8 wt.% of NaMA and containing 0.5 wt.% of ethylene glycol climethacrylate was mixed in the amount of 60 wtA with 40 wt.% of glycerol. This mixture was polymerized with 0.5 wt.% of benzoin ethyl ether related to the total amount of monomers for 15 minutes under UV radiation. The resulting material contains after swelling 56.5 wt.% of water at G0.199 MPa, K,=1.17 and K 1.08.

Example 28 A mixture consisting of 97.5 wt.% of HEMA and 2.5 wt.% of NaMA and containing 0.5 wt.% of ethylene glycol climethacrylate was mixed in the amount of 60 wtA with 40 wt.% of glycerol. This mixture was polymerized with 0.5 wt.% of benzoin ethyl ether related to the total amount of monomers for 15 minutes under UV radiation. The resulting material contains after swelling 60.2 wt.% of water at G0.215 MPa, Kw=1.21 and Ks=l.l 1.

Example 29 A mixture consisting of 97 wt.% of HEMA and 3 wtA of NaMA and containing 0.5 GB2196973A 5 wt.% of ethylene glycol dimethacrylate was mixed in the amount of 60 wt.% with 40 wt.% of glycerol. This mixture was polymerized with 0.5 wt.% of benzoin ethyl ether re- lated to the total amount of monomers for 15 minutes under UV radiation. The resulting material contains after swelling 65.5 wt.% of water at G=0. 229 MPa, Kw= 1.25 and K= 1. 14.

Example 30 A mixture consisting of 69.5 wt.% of HEMA, 0.5 wt.% of NaMA and 30 wt.% of DEGMA and containing 0.3 wt.% of ethylene glycol dimethacrylate and 0.3 wt.% of diethylene glycol dimethacrylate was mixed in the amount of 90 wt.% with 10 wt.% of glycerol. This mixture was polymerized with 0.5 wt.% of benzoin ethyl ether related to the total amount of monomers for 15 minutes under UV radiation. The resulting material contains after swelling 49.1 wt.% of water at G=0.169 MPa.

Example 31 A mixture consisting of 69.3 wt.% of HEMA 0.7 wt.% of NaMA and 30 wt.% of DEGMA and containing 0.3 wt.% of ethylene-bis-acrylamide and 0. 2 wt.% of diethylene glycol di- methacrylate was mixed in the amount of 90 wt.% with 10 wt.% of glycerol. This mixture was polymerized with 0.5 wt.% of benzoin ethyl ether related to the total amount of monomers for 15 minutes under UV radiation.

The resulting material contains after swelling 51.4 wt.% of water at G=0. 174 MPa.

Example 32 A mixture consisting of 69.1 wt.% of HEMA, 0.9 wt.% of NaMA, and 30 wt.% of DEGMA and containing 0.3 wt.% of ethylene glycol dimethacrylate and 0.3 wt.% of diethylene glycol dimethacrylate was mixed in the amount of 90 wt.% with 10 wt.% of diacetine. This mixture was polymerized with 0.5 wt.% of benzoin ethyl ether related to the total amount of monomers for 15 minutes under UV radiation. The resulting material contains after swelling 54.6 wt.% of water at G=0.182 MPa.

Example 33

A mixture with the composition 69.9 wt.% of HEMA, 0.1 wt.% of NaMA and 30 wt.% of DEGMA containing 0.3 wt.% of ethylene gly- 120 col dimethacrylate and 0.3 wt.% of diethylene glycol dimethacrylate was mixed in the amount of 80 wt.% with 20 wt.% of glycerol.

This mixture was polymerized with 0.5 wt.% of benzoin ethyl ether related to the total amount of monomers for 15 minutes under UV radiation. The resulting material contains after swelling 49.6 wt.% of water at G=0.139 MPa.

Example 34 A mixture consisting of 69.7 wt.% of HEMA, 0.3 wt.% of NaMA and 30 wt.% of DEGMA and containing 0.3 wt.% of ethylene glycol dimethacrylate and 0.3 wt.% of diethylene glycol dimethacrylate was mixed in the amount of 80 wt.% with 20 wt.% of dimethylsulfoxide. This mixture was polymerized with 0.5 wt.% of benzoin ethyl ether related to the total amount of monomers for 15 min under UV radiation. The resulting material contains after swelling 49.6 wt.% of water at G=0.142 MPa.

Example 35 A mixture consisting of 69.5 wt.% of HEMA, 0.5 wt.% of NaMA and 30 wt.% of DEGMA and containing 0.3 wt.% of ethylene glycol dimethacrylate and 0.3 wt.% of diethylene gly- col dimethacrylate was mixed in the amount of 80 wt.% with 20 wt.% of glycerol. This mixture was polymerized with 0,5 wt.%- of benzoin ethyl ether related to the total amount of monomers for 15 minutes under UV radia- tion. The resulting material contains after swelling 51.3 wt.% of water at G=0.147 MPa.

Example 36

A mixture with the composition 69.3 wt.% of HEMA, 0.7 wt.% of NaMA and 30 wt.% of DEGMA containing 0.3 wt.% of ethylene glyof diethylene in the of glycerol. with 0.5 wt.% to the total amount of monomers for 15 minutes under UV radiation. The resulting material contains 105 after swelling 53. 4 wt.% of water at G0.153 MPa.

col dimethacrylate and 0.3 wt.% glycol dimethacrylate was mixed amount of 80 wt.% with 20 wt.OX The mixture was polymerized of benzoin ethyl ether related Example 37 A mixture consisting of 69.1 wt.% of HEMA, 0.9 wt.% of NaMA and 30 wt.% of DEGMA and containing 0.3 wt.% of ethylene glycol dimethacrylate and 0.3 wt.% of diethylene glycol dimethacrylate was mixed in the amount of 80 wt.% with 20 wt.% of glycerol. This, mixture was polymerozed with 0.5 wt.% of benzoin ethyl ether related to the total amount of monomers for 15 minutes under UV radiation. The resulting material contains after swelling 58.8 wt.% of water at G=0.161.

Example 38 A mixture consisting of 69.9 wtA of HEMA, 0.1 wt.% of NaMA and 30 wt.%- of DEGMA and containing 0.3 wt.% of ethylene-bis-acry- lamide and 0.2 wtA of diethylene glycol dimethacrylate was mixed in the amount of 70 wtA with 30 wt.% of dimethylsulfoxide. This mixture was polymerized with 0.5 wt.% of benzoin ethyl ether related to the total amonut of monomers for 15 min under UV radiation.

6 The resulting material contained after swelling 50.1 wt.% of water at G=0. 121 MPa, K,= 1. 13 and K,= 1. 11.

Example 39 A mixture consisting of 69.7 wt.% of HEMA, 0.3 wt.% of NaMA and 30 wt.% of DEGMA and containing 0.3 wt.% of ethylene glycol dimethacrylate and 0.3 wt.% diethylene glycol dimethacrylate was mixed in the amount of 70 wt.% with 30 wt.% of glycerol. This mixture was polymerized with 0.5 wt.% of benzoin ethyl ether related to the total amount of monomers for 15 minutes under UV radiation.

The resulting material contains after swelling 50.7 wt.% of water at G=0. 125 MPa, Kw1.15 and K,=1.12. Example 40 A mixture consisting of 69.5 wt.% of HEMA, 0.5 wtA of NaMA and 30 wt.% of DEGMA and containing 0.3 wt.% of ethylene glycol dimethacrylate and 0.3 wt.% of diethylene gly col dimethacrylate was mixed in the amount of 70 wt.% with 30 wt.% of glycerol. This mixture was polymerized with 0.5 wt.% of benzoin ethyl ether related to the total amount of monomers for 15 minutes under UV radia tion. The resulting material contains after swelling 54.2 wt.% of water at G=0.129 MPa, Kw 1. 18 and Ks= 1. 14.

Example 41

A mixture consisting of 69.3 wt.% of HEMA, 0.7 wt.% of NaMA and 30 wt.% of DEGMA and containing 0.3 wt.% of ethylene glycol 100 dimethacrylate and 0.3 wt.% of diethylene gly col climethacrylate was mixed in the amount of 70 wt.% with 30 wt.% of glycerol. This mixture was polymerized with 0.5 wt.% ben zoin ethyl ether related to the total amount of monomers for 15 minutes under UV radiation.

The resulting material contains after swelling 55.3 wtA of water at G=0.135 MPa, K,=1.22 and K,=1.15.

Example 42 A mixture consisting of 69.1 wt.% of HEMA, 0.9 wt.% of NaMA and 30 wt.% of DEGMA and containing 0.3 wt.% of ethylene glycol climethacrylate and 0.3 wt.% of diethylene glycol dimethacrylate was mixed in the amount of 70 wt.% with 30 wt.% of glycerol. This mixture was polymerized with 0.5 wt.% of benzoin ethyl ether related to the total amount of monomers for 15 minutes under UV radiation. The resulting material contains after swelling 61.3 wt.% of water at G=0.139 MPa, Kw=1.23 and K, =1.16.

Example 43 A mixture with composition 69.9 wt.% of HEMA, 0.1 wt.% of NaMA and 30 wt.% of DEGMA containing 0.3 wt.% ethylene glycol dimethacrylate and 0.3 wt.% of diethylene gly- col dimethacrylate was mixed in the amount GB2196973A 6 of 60 wt.% with 40 wt.% of glycerol. This mixture was polymerized with 0. 5 wt.% of benzoin ethyl ether related to the total amount of monomers for 15 minutes under UV radia- tion. The resulting material contains after swelling 51.8 wt.% of water at G=0.103 MPa, K,=1.10 and Ks=1.08.

Example 44

A mixture with composition 69.7 wt.% of HEMA, 0.3 wt.% of NaMA and 30 wt. % of DEGMA containing 0.3 wt.% of ethylene glycol dimethacrylate and 0.3 wt.% of diethylene glycol dimethacrylate was mixed in the amount 60 wt.% with 40 wt.% of glycerol. This mixture was polymerized with 0.5 wt.% of benzoin ethyl ether related to the total amount of monomers for 15 minutes under UV radiation. The resulting material contains after swelling 51.8 wt.% of water at G=O. 108 MPa, Kw= 1. 11 and K. 1.09.

Example 45 A mixture with composition 69.5 wt.% of HEMA, 0.5 wt.% of NaMA and 30 wt.% of DEGMA containing 0.3 wt.% of ethylene glycol dimethacrylate was mixed in the amount of 60 wt.% with 40 wt.% of glycerol. This mixture was polymerized with 0.5 wt.% of benzoin ethyl ether related to the total amount of monomers for 15 minutes under UV radiation. The resulting material contains after swelling 58.9 wt.% of water at G=O. 112 MPa, K,=1.15 and K,=1.10.

Example 46 A mixture consisting of 69.3 wt.% of HEMA, 0.7 wt.% of NaMA and 30 wt.% of DEGMA and containing 0.3 wt.% of ethylene glycol dimethacrylate and 0.3 wt.% of diethylene glycol dimethacrylate was mixed in the amount of 60 wt.% with 40 wt.% of glycerol. This mixture was polymerized with 0.5 wt.% of benzoin ethyl ether related to the total amount of monomers for 15minutes under UV radiation. The resulting material contains after swelling 61.3 wt.% of water at G= 0. 114 MPa, K,= 1. 17 and K,= 1. 11.

Example 47 A mixture consisting of 69.1 wt.% of HEMA, 0.9 wt.% of NaMA and 30 wt.% of DEGMA and containing 0.3 wt.% of ethylene glycol dimethacrylate and 0.3 wt.% of diethylene glycol dimethacrylate was mixed in the amount of 60 wt.% with 40 wt.% of glycerol. This mixture was polymerized with 0.5 wt.% of benzoin ethyl ether related to the total amount of monomers for 15 minutes under UV radia- tion. The resulting material contains after swelling 64.9 wtA of water at G=O. 118 MPa, K,=1.23 and K,=1.12.

Example 48

A mixture consisting of 97.5 wt.% of HEMA 7 GB 2 196 973A 7 and 2.5 wt.% of NaMA and containing 0.2 wt.% of ethylene glycol dimethacrylate was mixed in the amount of 70 wt.% with 30, wt.% of glycerol. This mixture was polymer- ized with 0.5 wt.% of benzoin ethyl ether related to the total amount of monomers for 15 minutes under UV radiation. The resulting material contains after swelling 60.1 wt.% of water at G=0.242 MPa.

Example 49 A mixture with composition 97.5 wt.% of HEMA and 2.5 wt.% of NaMA containing 0.7 wt.% of ethylene glycol dimethacrylate and 0.4 wt.% of diethylene glycol dimethacrylate was mixed in the amount of 70 wt.% with 30 wt.% of glycerol. This mixture was polymerized with 0.5 wt.% of benzoin ethyl ether related to the total amount of monomers for 15 minutes under UV radiation. The resulting material contains after swelling 59.2 wt.% of water at G=0.266 MPa.

Example 50 A mixture consisting of 69.5 wt.% of HEMA, 0.5 wt.% of potassium methacrylate and 30 wt.% of DEGMA and containing 0.2 wt.% of ethylene glycol dimethacrylate was mixed in the amount of 70 wt.% with 30 wt.% of gly- cerol. This mixture was polymerized with 0.5 wt.% of benzoin ethyl ether related to the total amount of monomers for 15 minutes- under UV radiation. The resulting material contains after swelling 55 wt.% of water at G=O. 118 MPa.

Example 51 A mixture with the composition 69.5 wt.% of HEMA, 0.5 wt.% of NaMA and 30 wt.% of DEGMA containing 0.7 wt.% of ethylene glycol dimethacrylate and 0.4 wt.% of diethylene glycol dimethacrylate was mixed in the amount of 70 wt.% with 30 wt.% of glycerol. This mixture was polymerized with 0.5 wt.% of benzoin ethyl ether related to the total amount of monomers for 15 minutes under UV radiation. The resulting material contains after swelling 53.7 wt.% of water at G=0.140 MPa.

Example 52 A mixture with the composition 97.5 wtA of HEMA and 2.5 wt.% of NaMA containing 0.5 wt.% of ethylene glycol dimethacrylate was mixed in the amount of 70 wt.% with 30 wtA of glycerol. This mixture was polymerized with 0.2 wt.% of azobisisobutyronitrile related to the total amount of monomers for 16 hours at 60'C. The resulting material con- tains after swelling 59.5 wtA of water at G=0.250 MPa.

wtA of ethylene glycol dimethacrylate was mixed in the amount of 70 wt.% with 30 wt.% of glycerol. The mixture was polymerized with 0.1 wt.% dilsopropyl peroxocarbo- nate related to the total amount of monomers for 16 hours at 600C, The resulting material contains after swelling 59.4 wt.% of water at G=0.251 MPa.

Example 54 A mixture with the composition 97.5 wt.% of HEMA and 2.5 wt.% of NaMA containing 0.5 wt.% of ethylene glycol dimethacrylate was mixed in the amount of 70 wt.% with 30 wtA of glycerol. This mixture was polymerized with 0.2 wt.% of ammonium persulfate related to the total amount of monomers for 1 hour at 78C. The resulting material contains after swelling 59.4 wtA of water at G=0.253 MPa.

Example 55 A mixture with the composition 97.5 wt.% of HEMA and 2.5 wt.% of NaMA containing 0.5 wt.% of ethylene glycol dimethacrylate was mixed in the amount of 70 wt.% with 30 wt.% of glycerol. This mixture was polymerized with 0.5 wt.% of benzoin ethyl ether related to the total amount of monomers for 15 minutes under UV radiation. The resulting material contains after swelling 59.3 wt.% of water at G=0.252 MPa.

Example 56

A mixture consisting of 69.5 wt.% of HEMA, 0.5 wt.% of NaMA and 30 wt.% of DEGMA and containing 0.3 wt.% of ethylene glycol dimethacrylate and 0. 3 wt.% of diethylene glycol dimethacrylate was mixed in the amount of 70 wt.% with 30 wt.% of glycerol. This mixture was polymerized with 01 wt.% of azobisisobutyronitrile related to the total amount of monomers for 16 hours at 60'C. The resulting material contains after swelling 54 wt. % of water at G = 0. 130 MPa.

Example 57 A mixture consisting of 69.5 wt.% of HEMA, 0.5 wt.% of NaMA and 30 wt.% of DEGMA and containing 0.3 wt.% of ethylene glycol dimethacrylate and 0.3 wt.% of diethylene glycol dimethacrylate was mixed in the amount of 70 wt.% with 30 wt.% of glycerol. The mixture was polymerized with 0,1 wtA of diisopropyl peroxocarbonate related to the total amount of monomers for 16 hours at 60'C. The resulting material contains after swelling 54.3 wt. % of water at G=0.128 MPa.

Example 53

A mixture with the composition 97.5 wt.% of HEMA and 2.5 wt.% of NaMA containing-0.5130 Example 58 A mixture consisting of 69.5 wt.% of HEMA, 0.5 wt.% of NaMA and 30 wt.% of DEGMA and containing 0.3 wt.% of ethylene glycol dimethacrylate and 0.3 wt.% of diethylene gly- 8 col dimethacrylate was mixed in the amount of 70 wt.% with 30 wt.% of glycerol. The mixture was polymerized with 0.2 wt.% of ammonium persulfate related to the total amount of monomers for 1 hour at 78'C. The resulting material contained after swelling 54.1 wt.% of water at G=0.131 MPa.

Example 59

A mixture with the composition 69.5 wt.% of HEMA, 0.5 wt.% of NaMA and 30 wt.% of DEGMA containing 0.3 wt.% of ethylene gly col dimethacrylate and 0.3 wt.% of diethylene glycol dimethacrylate was mixed in the amount of 70 wt.% with 30 wt.% of glycerol.

This mixture was polymerized with 0.5 wt.% of benzoin methyl ether related to the total amount of monomers for 15 minutes under UV radiation. The resulting material contains after swelling 54.2 wt.% of water at G=0.129 MPa.

Example 60

A mixture with the composition 69.5 wt.% of HEMA, 0.5 wt.% of NaMA and 30 wt.% of DEGMA containing 4 wt.% triethylene glycol dimethacrylate was mixed in the amount of 60 wt.% with 40 wt.% of glycerol. This mixture was polymerized with 0.5 wt.% of benzoin isopropyl ether related to the total amount of 95 monomers for 15 minutes under UV radiation.

The resulting material contains after swelling 51 wt.% of water at G=0.19 MPa.

Example 61 A mixture consisting of 91 wt.% of HEMA and 9 wt.% of NaMA and containing 0.5 wt.% of ethylene glycol dimethacrylate was mixed in the amount of 70 wt.% with 30 40 wt.% of glycerol. The mixture was polymerized with 0.5 wt.% of benzoin methyl ether related to the total amount of monomers for 15 minutes under UV radiation. The resulting material contains after swelling 85 wt.% of water.

Example 62

A mixture consisting of 49.75 wt.1/o of HEMA, MA of DEGMA and 0.25 wt.% of NaMA and containing 0.3 wt.% of ethylene glycol dimethacrylate and 0.3 wtA of diethylene gly col dimethacrylate was mixed in the amount of 70 wt.% with 30 wt.%of glycerol. This mixture was polymerized with 0.5 wt.% of benzoin ethyl ether related to the total amount of monomers for 15 minutes under UV radia tion. The resulting material contains after swelling 61.5 wt.% of water.

Example 63 A mixture with the composition 97.5 wt.% of HEMA and 2.5 wt.% of ammonium methacrylate containing 0.5 wt.% of ethylene glycol dimethacrylate was mixed in the amount of 90 65 wt.% with 10 wt.% of glycerol. This mixture GB 2 196 973A 8 was polymerized with 0.5 wt.% benzoin ethyl ether related to the total amount of monomers for 15 minutes under UV radiation. The resulting material contains after swelling 56 wt.% of water at G=0.295 MPa.

Example 64 A mixture with the composition 98.7 wt.% of HEMA and 1.3 wt.% of sodium acrylate con- taining 0.5 wt.% of ethylene glycol dimethacrylate was mixed in the amount of 80 wt.% with 20 wt.% of glycerol. This mixture was polymerized with 0.5 wt.% of benzoin ethyl ether related to the total amount of monomers for 15 minutes under UV radiation. The resulting material contains after swelling 53 wt.% of water at G=0.26 MPa.

Example 65

A mixture with the composition 98.7 wt.% of HEMA and 1.3 wt.% of potassium acrylate containing 0.5 wt.% of ethylene glycol dimethacrylate was mixed in the amount of 80 wt.% with 20 wt.% of glycerol. The mixture was polymerized with 0.5 wt.% of benzoin ethyl ether related to the total amount of monomers for 15 minutes under UV radiation. The resulting material contains after swelling 52.5 wt.% of water at G=0.26 MPa.

Example 66 A mixture consisting of 97 wt.% of HEMA and 3 wt.% of methacrylic acid and containing 0.5 wtA of ethylene glycol dimethacrylate was mixed in the amount of 90 wt.% with 10 wt.% of glycerol. This mixture was polymerized with 0.5 wt.% of benzoin ethyl ether related to the total amount of monomers between a glass plate and a poly(tetrafluoroethy- lene) plate for 15 minutes under UV radiation. The resulting film was conditioned in an alcoholic solution of sodium hydroxide and then washed with distilled water. The swollen film contained 56 wt.% of water at G=0. 3 MPa.

Example 67 The film prepared according to Example 66 was conditioned in an aqueous solution of ammonium hydroxide and then washed with distilled water. This film contained in the swollen state 60.3 wt.% of water at G=0.3 MPa.

Example 68

A mixture consisting of 97 wt.% of HEMA and 3 wt.% of acrylic acid and containing 0.5 wt.% of ethylene glycol dimethacrylate was mixed in the amount of 90 wt.% with 10 wt.% of glycerol. A film was prepared from this mixture in the same way as in Example 66. This film underwent conditionation in an alcoholic solution of sodium hydroxide and then was washed with distilled water and measured. The water content was 61 wt.% at G=0.295 MPa.

9 GB2196973A 9 Example 69 The film prepared according to Example 68 underwent conditionation in an alcoholic solution of potassium hydroxide and then was washed with distilled water. This film exhibited similar results as in Example 68.

Example 70

A mixture with the composition 95 wt.% of HEMA and 5 wt.% of methacrylic acid con taining 0.5 wt.% of ethylene glycol dimetha crylate was mixed in the amount of 80 wt.% with 20 wt.% of glycerol. This mixture was polymerized with 0.5 wt.% of benzoin ethyl ether related to the total amount of monomers for 15 min under UV radiation. The resulting material contains after swelling 42 wt.% of water.

Example 71

A mixture with the composition 95 wt.% of HEMA and 5 wt.% of acrylic acid containing 0.5 wt.% of ethylene glycol dimethacrylate was mixed in the amount of 80 wt.% with 20 wt.% of glycerol. This mixture was polymer ized with 0.5 wt.% of benzoin ethyl ether re lated to the total amount of monomers for 15 minutes under UV radiation. The resulting ma terial contains after swelling 45 wt.% of 95 water.

The copolymers according to the invention have pronouncedly better mechanical proper ties than the crosslinked copolymer of DEGMA and often comparable with the mechanical properties of HEMA, which are always suited to the applications according to the invention.

The copolymers according to the invention are practically free of water-soluble extracts and secures a sufficiently high equilibrium content of water in the obtained gel at the retained suitable optical and mechanical properties, so that they can be used for the production of contact lenses for permanent wearing. 110

Claims

1. Hydrophilic copolymer which can be prepared by the copolymerization of a monomer mixture of 2-hydroxyethyl methacrylate and 2(2-hydroxyethoxy) ethyl methacrylate in the amount of 90 to 99.99 wt.% with the free methacrylic acid or acrylic acid or with their sodium, potassium and ammonium salts in the amount of 10 to 0.01 wt.% in the presence of radical initiators, whereas the monomer mixture of 2-hydroxyethyl methacrylate and 2(2-hyd roxyethoxy) ethyl methacrylate contains 0 to 50 wt.% of 2-(2-hyd roxyethoxy) ethyl meth- acrylate and the entire monomer mixture contains 0.01 to 4 wt.% of a crosslinking agent having at least tA olefinic double bonds.

2. The hydrophilic copolymer according to Claim 1, wherein the crosslinking agent is cho- sen from the group comprising multifunctional esters or amides of acrylic acid or methacrylic acid.

3. The. hydrophilic copolymer according to Claims 1. and 2, wherein the radical initiators are chosen from the group comprising azo compounds, peroxides, peroxocarbonates, persulfates, photoinitiators based on benzoin eth_ers and their derivatives, and initiation redox systems, as are advantageously persulfate.-metabisulfite, persulfate-alkylamines, and benzoyl peroxide-alkylamines.

4. The hydrophilic copolymer according to Claims 1 through 3, wherein the copolymerization is carried out in the presence of polar solvents,as are advantageously glycerol, glycols and their derivatives, water, dimethylformamide, dimethylsulfoxide, dimethylacetamide, diacetine, isopropanol, or their mixtures. -

5. The hydrophilic copolymer according to Claims 1 through 4, wherein the ratio of the solvent to the monomer mixture ranges from 1:99 to 50:50 (percent).

6. Method for producing the hydrophilic copolymer according to any of the Claims 1 through 5, wherein a monomer mixture of 2hydroxyethyl methacrylate and 2- (2-hydroxyethoxy)ethyl methacrylate in the amount of 90 to 99.99 wt.% is copolymerized with sodium, potassium and ammonium salts of methacrylic acid or acrylic acid in the amount of 10 to 0.01 wt.% in the presence of radical initiators and in the presence of 0.01 to 4 wt.%, related to the entire mixture of monomers, of a crosslinking agent having at least two olefinic double bonds, whereas the content of 2-(2hydroxyethoxy)ethyl methacrylate in the monomer mixture of 2-hydroxyethyl methacrylate and 2-(2-hyd roxyethoxy) ethyl methacrylate is from 0 to 50 wt.%.

7. Method for producing the hydrophilic copolymer according to any of the Claims 1 through 5, wherein a monomer mixture of 2hydroxyethyl methacrylate and 2-(2-hydroxyethoxy)ethyl methacrylate in the amount of 90 to 99.99 wt.% is copolymerized with sodium, potassium or ammonium salts of methacrylic acid or acrylic acid in the amount of 10 to O.Olwt.% in the presence of radical initiators and in the presence of 0.01 to 4 wt. %, related to the entire mixture of monomers, of a crosslinking agent having at least two olefinic double bonds, whereas the content of 2-(2hyd roxyethoxy) ethyl methacrylate in the monomer mixture of 2-hydroxyethyl methacrylate and 2-(2-hydroxyethoxy) ethyl methacrylate is from 0 to 50 wt.%.

8. The method according to Claim 6, wherein the prepared copolymer is conditioned in aqueous or alcoholic solutions of sodium, potassium or ammonium hydroxide or of their salts with weak acids and subsequently washed, preferably with distilled water.

9. The method according to any of the Claims 6 through 8, wherein the copolymeriza- tion is carried out in the presence of a polar GB 2 196 973A 10 solvent or a mixture of polar solvents.

10. The method according to Claims 6 through 9, wherein a solvent or also the water-soluble low-molecular weight portions present in the crosslinked copolymer are extracted with water and the copolymer is then dried to a constant weight.

11. The method according to Claims 6 through 10, wherein the drying is carried out in the medium of saturated steam above the glass-transition temperature T. of the prepared copolymer.

12. A method as claimed in Claim 1 substantially as described in any of the examples disclosed herein.

Published 1988 at The Patent Office, State House, 66/71 High Holborn, London WC 1 R 4TP. Further copies may be obtained from The Patent Office, Sales Branch, St Mary Cray, Orpington, Kent BR5 3RD. Printed by Burgess & Son (Abingdon) Ltd. Con. 1/87.