FR2600658A1 - Hydrophilic copolymer and process for its manufacture - Google Patents

Abstract

THE INVENTION DEALS WITH A HYDROPHILIC COPOLYMER AND ITS PREPARATION PROCESS. THE COPOLYMER IS PREPARED BY COPOLYMERIZATION OF A MIXTURE OF MONOMERS OF 2-HYDROXYETHYL METHACRYLATE AND 2- (2-HYDROXYETHOXY) ETHYL METHACRYLATE, AT 90 TO 99.99 BY WEIGHT, WITH METHACRYLIC ACID OR ACRYLIC ACID FREE OR WITH THEIR SALTS OF SODIUM, POTASSIUM OR AMMONIUM, AT A RATIO OF 10 TO 0.01 BY WEIGHT, IN THE PRESENCE OF RADICAL INITIATORS, THE CONTENT OF 2- (2-HYDROXYETHOXY) ETHYL METHACRYLATE IN THE MIXTURE OF 2- MONOMERS HYDROXYETHYL METHACRYLATE AND 2- (2-HYDROXYETHOXY) ETHYL METHACRYLATE BEING 0 TO 50 BY WEIGHT AND THE TOTAL MIXTURE OF MONOMERS CONTAINING 0.01 TO 4 BY WEIGHT OF A CROSSLINING AGENT CONTAINING AT LEAST TWO DOUBLE LINKAGES. THE HYDROPHILIC COPOLYMER IS SUITABLE FOR CONTACT LENSES AND MEDICAL APPLICATIONS.

Description

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  The invention relates to a hydrophilic copolymer suitable especially for contact lenses and uses

  medical devices and a process for its manufacture.

  Water-swellable elastomers of various equilibrium water contents are known and are used in the manufacture of soft hydrophilic contact lenses and for a wide variety of medical applications. For applications where it is important that the mechanical characteristics are suitable and a water content of about 40% by weight is sufficient, the polymers of 2-hydroxyethyl methacrylate (HEMA) have been excellent. However, a number of applications (eg contact lenses

  for permanent wear) require materials with a high swelling capacity, often with a lower shear modulus of elasticity, but sufficient elongation.

  Nevertheless, the hydrophilic polymers known hitherto have, for a high swelling capacity, inadequate mechanical characteristics to the point of rendering them unusable. As a result, slightly crosslinked copolymers of highly hydrophilic N-vinylpyrrolidone with hydrophobic alkyl methacrylate (GB patent) were developed.

  1,514,810), which offer better mechanical characteristics in combination with the high swelling capacity.

  However, they contain an undesirable proportion of extractable bodies.

  Diethylene glycol methacrylate (2- (2-hydroxyethoxy) ethyl methacrylate), a homologue of 2-hydroxyethyl methacrylate, gives a polymer with a high swelling capacity thanks to its oxygen ether atom in the ester chain, but which is not not equipped with suitable mechanical characteristics even in the cross-linked state and can not therefore serve

to certain applications.

  The abovementioned disadvantages are eliminated in a hydrophilic copolymer according to the invention, suitable for all contact lenses and medical applications, which can be prepared by copolymerizing a monomer mixture containing 2-hydroxyethyl methacrylate (HEMA) and 2-hydroxyethyl methacrylate (HEMA). - (2-hydroxyethoxy) ethyl methacrylate (diethylene glycol

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  methacrylate - DEGMA), at a rate of 90 to 99.99% by weight, with free methacrylic acid or acrylic acid or with their sodium, potassium and ammonium salts, in a proportion of 10 to 0.01 % by weight, in the presence of radical initiators, the content of 2- (2-hydroxyethyl) methyl methacrylate of the monomer mixture 2-hydroxyethyl methacrylate

  2- (2-hydroxyethoxy) ethyl methacrylate being from 0 to 50% by weight and the total monomer mixture containing from 0.01 to 4% by weight of a crosslinking agent having at least two olefinic double bonds.

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

  The radical initiators are selected from azo compounds, peroxides, peroxocarbonates, persulfates,

  photoinitiators based on benzoin ethers and their derivatives, and also the initiation redox systems, advantageously persulfatemétabisulfite, persulfate-alkylamines, or benzoylealkylamine peroxide, preferably at a concentration of 0.01 to 3% in weight.

  The copolymerization may be carried out in the presence of polar solvents, advantageously glycols, glycols and their derivatives, water, dimethylformamide, dimethylsulfoxide, dimethylacetamide, diacetin, isopropanol or mixtures thereof. The ratio of solvent to monomer mixture can range from 1/99 to

/ 50 (% by weight).

  If it is methacrylic acid or free acrylic acid used in the manufacture of the hydrophilic copolymer according to the invention, the copolymer obtained can be advantageously reconditioned in aqueous or alcoholic solutions of sodium hydroxide, potassium or ammonium, or their salts with weak acids, and then wash it, advantageously with distilled water. In this way, the free carboxylic group is converted to sodium salt, potassium salt or ammonium, which has the effect of increasing the solvation in the vicinity of these COOX groups (where X = Na, K or NH4) and increase the overall swelling capacity of

the 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 particularly suitable for

  applications requiring further mechanical work. All the same, some articles can also be manufactured directly by this bulk copolymerization.

  In the presence of the aforementioned polar solvents, individually or in admixture, a copolymer with a selected solvent content is prepared which is suitable for molding, for example centrifugal casting of contact lenses. The solvent used, which is opposed to mechanical work in the first case,

  here favorably influences the swelling pressures arising during the swelling of the final article.

  This makes it possible, and even advantageous, in the manufacture of contact lenses with a high swelling capacity to be machined on the lathe, to extract with water the solvent, or also low molecular weight fractions which are soluble in water. in the crosslinked copolymer prepared in the presence of said polar solvents with water, then to bring the polymer back to a constant weight by drying. The resulting xerogel lends itself perfectly to mechanical work. It is then possible to advantageously ensure drying in saturated steam at a temperature greater than that of the glass transition,

T, of the copolymer prepared.

  The advantage of this way of proceeding, compared to the mode of preparation of contact lenses from various types of xerogels used up to now, lies in the possibility not only of perfectly removing low molecular weight substances by washing as indicated above, but also to obtain a more orderly structure as to the internal stress of the crosslinking bonds, which subsists during drying and endows the contact lenses made from the thus prepared xerogel of a polymer network. free from internal stress

  after the re-inflation thanks to the ordered structure of the crosslinking bonds, which is visible to polarized light.

  In addition, this preparation process ensures a high degree of

  conversion of the polymerized constituents with respect to

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  gel prepared by polymerization without solvent.

  Another advantage of this process is that the glass transition temperature T increases by about 60 ° C. with each percent of low molecular weight monomer and fraction removed by washing, favorably affecting lathe machining and polishing. putting the contact lens in its final form. The drying in superheated steam of prefabricated water-swelled elements for lathe-machined contact lenses is advantageous because the polymerization solvent, i.e., water, is removed from a structure. three-dimensional under conditions of perfect mobility of the polymer chains and their lateral segments (that is to say above T of the copolymer), which ensures rapid removal of the solvent without damage to the three-dimensional structure with maintenance of the ratio between external dimensions and angles of the dried prefabricated element with respect to the inflated element having the initial composition

  given the polymerization mixture.

  Copolymers of 2-hydroxyethyl methacrylate were prepared with diethylene glycol monomethacrylate and with sodium, potassium or ammonium methacrylate in the presence of diethylene glycol dimethacrylate and ethylene glycol dimethacrylate, or in the presence of a single component of crosslinking which may be an arbitrary diester of methacrylic acid or acrylic acid and the corresponding alkylene glycols if the starting monomers are completely free of their own diesters from their synthesis, or methylene can be used; bis-acrylamide, ethylene-bis-methacrylamide, hexamethylene-bis-methacrylamide, as well as others, or combinations thereof as a crosslinking component so that at least three constituents, including two

  have an olefinic double bond and of which the third is a crosslinking agent.

  The invention is further illustrated by the examples of

  implementation below, devoid of any limiting character.

Example 1

  A mixture consisting of 99.7% by weight of 2-hydroxyethyl methacrylate (hereinafter referred to as HEMA) and 0.3% by weight of sodium methacrylate (hereinafter referred to as NaMA) is polymerized. ) and containing 0.3% by weight of ethylene glycol dimethacrylate with 0.1% by weight, relative to the total amount of monomers, of diisopropyl peroxocarbonate, for 16 hours at 60 C. The resulting material contains after swelling 38% by weight. weight of water, with a modulus of elasticity in shear G = 0.305 MPa.

Example 2

  A mixture consisting of 99.4% by weight HEMA and 0.6% by weight NaMA and containing 0.3% by weight ethylene glycol dimethacrylate was polymerized with 0.1% by weight based on total amount of monomers, diisopropyl peroxocarbonate for 16 hours at 600C. The resulting material contains after swelling 40% by weight of water, with G = 0.315 MPa.

Example 3

  A mixture of 98.7% by weight of HEMA and 1.3% by weight of potassium methacrylate and containing 0.3% by weight of ethylene glycol dimethacrylate was polymerized with 0.1% by weight based on the total amount of monomers, diisopropyl peroxocarbonate, for 16 hours at 600C. The resulting material contains after swelling 45% by weight

of water, with G = 0.325 MPa.

Example 4

  A mixture composed of 98.2% by weight of HEMA and 1.8% by weight of NaMA and containing 0.3% was polymerized. by weight of ethylene glycol dimethacrylate, with 0.1%, by weight relative to the total amount of monomers, diisopropyl peroxocarbonate, for 16 hours at 60 C. The resulting material contains 48% by weight of water after swelling, with G = 0.340 MPao

Example 5

  A mixture composed of 97.5% by weight of HEMA and 2.5% by weight of potassium methacrylate and containing 0.3% by weight of ethylene glycol dimethacrylate is polymerized with

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  0.1% by weight relative to the total amount of monomers of diisopropyl peroxocarbonate for 16 hours at 600 ° C. The resulting material contains after swelling 50% by weight

of water, with G = 0.350 MPa.

Example 6

  A mixture composed of 97% by weight of HE} A and 3% by weight of NaNA and containing 0.3% by weight of ethylene glycol dimethacrylate was polymerized with 0.1% by weight, based on the total amount of monomers, diisopropyl peroxocarbonate, for 16 hours at 600C. The resulting material contains

  after swelling 55% by weight of water, with G = 0.361 MPa.

Example 7

  A mixture of 96% by weight of HEMA and 4% by weight of NaNA and containing 0.3% by weight of ethylene glycol dimethacrylate was polymerized with 0.1% by weight based on the total amount of monomers. , diisopropyl peroxocarbonate,

  for 16 hours at 600C. The resulting material contains after swelling 57% by weight of water, with G = 0.372 IPa.

Example 8

  A mixture composed of 95% by weight of HERA and 5% by weight of NaNYA and containing 0.3% by weight of ethylene glycol dimethacrylate was polymerized with 0.1% by weight, based on the total amount of monomers. , diisopropyl peroxocarbonate,

  for 16 hours at 600C. The resulting material contains after swelling 63% water, with G = 0.380 MPa.

Example 9

  A mixture composed of 69.9% by weight of HEMA, 30% by weight of diethylene glycol monomethacrylate (hereinafter referred to as DEGMA) and 0.1% by weight of NaMA and containing 0, is polymerized. 2% by weight of ethylene glycol dimethacrylate with 0.1% by weight, based on the total amount of monomers, of diisopropyl peroxocarbonate, for 16 hours at 60 ° C. The resulting material contains after swelling 46% by weight of water, with G = 0.165 MPa. EXAMPLE 10 A blend of 69.75% by weight of HEMA, 30% by weight of diethylene glycol monomethacrylate (hereinafter referred to as DEGMA) and 0.25% by weight is polymerized.

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  of NaMA and containing 0.2% by weight of ethylene glycol dimethacrylate with 0.1%, by weight based on the total amount of monomers, of diisopropyl peroxocarbonate, for 16 hours at 60 C. The resulting material contains after swelling 48% by weight of water, with G = 0.170 MPa.

Example 11l

  A mixture of 69.5% by weight of HEMA, 30% by weight of DEGMA and 0.5% by weight of NaMA and containing 0.2% by weight of ethylene glycol dimethacrylate 10 and 0 is polymerized. 1% by weight of diethylene glycol dimethacrylate with 0.1% by weight based on the total amount of monomers of diisopropyl peroxocarbonate for 16 hours at 600C. The resulting material contains after swelling 50% / wt.

of water, with G = 0.170 KPa.

Example 12

  A mixture composed of 69.2% by weight of HEMA, 30% by weight of DEGMA and 0.8% by weight of NaMA and containing 0.2% by weight of ethylene glycol dimethacrylate and 0.1 % by weight of diethylene glycol dimethacrylate with 0.1%, by weight relative to the total amount of monomers, of diisopropyl peroxocarbonate, for 16 hours at 600 ° C. The resulting material contains after swelling 52% by weight

of water, with G = 0.180 MPa.

Example 13

  A composition composed of 69% by weight of HEMA, 30% by weight of DEGMA and 1% by weight of NaMA and containing 0.2% by weight of ethylene glycol dimethacrylate and 0.2% by weight of diethylene glycol dimethacrylate with 0.1% by weight based on the total amount of monomers of diisopropyl peroxocarbonate for 16 hours at 60 ° C. The resulting material contains after swelling 55% by weight

of water, with G = 0.190 MPa.

Example 14

  90% by weight of a mixture composed of 98.7% by weight of HEMA and 1.3% by weight of NaXA and containing 0.5% by weight of ethylene glycol dimethacrylate are mixed at 90% by weight.

  as a crosslinking agent with 10% by weight of glycerol.

  The mixture is polymerized with 0.5% by weight based on

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  total amount of monomers, benzolene ethyl ether, for 15 minutes under ultraviolet radiation. The material

  resulting after swelling contains 47.8% by weight of water, with a modulus of elasticity in shear G = 0.283 MPa.

Example 15

  90% by weight of a mixture composed of 98.2% by weight of HEMA and 1.8% by weight of NaMA and containing 0.5% by weight of ethylene glycol dimethacrylate with% by weight of diac6tine. The mixture is polymerized with 0.5%, by weight based on the total amount of benzolene ethyl ether monomers, for 15 minutes under ultraviolet radiation. The resulting material contains after swelling

  , 5% by weight of water, with G = 0.290 MPa.

Example 16

  90% by weight of a mixture composed of 97.5% by weight of HEMA and 2.5% by weight of NaMA and containing 0.5% by weight of ethylene glycol dimethacrylate with% by weight of glycerol. The mixture is polymerized with 0.5%, by weight based on the total amount of monomers, of benzol ethyl ether, for 15 minutes under ultraviolet radiation. The resulting material contains after swelling

  52.4% by weight of water, with G = 0.300 MPa.

Example 17

  A mixture consisting of 97% by weight of HEXA and 3% by weight of NaMA and containing 0.5% by weight of ethylene glycol dimethacrylate with 10% by weight of glycerol is mixed at a rate of 90% by weight. The mixture is polymerized with 0.5%, by weight based on the total amount of monomers, of benzol ethyl ether for 15 minutes under ultraviolet radiation. The resulting material contains after swelling

  56.2% by weight of water, with G = 0.309 MPa.

Example 18

  80% by weight of a mixture of 98.7% by weight of HEMA and 1.3% by weight of NaMA and containing 0.4% by weight of hexamethylene-bis-acrylamide and 80% by weight are mixed. 35% by weight of methylenebisacrylamide with 20% by weight of glycerol. The mixture is polymerized with 0.5% by weight, based on the total amount of monomers, of diethyl ether.

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  benzolne, for 15 minutes under ultraviolet radiation.

  The resulting material contains after swelling 49.0% 5

weight of water, with G = 0.263 MPa.

Example 19

  80% by weight of a mixture composed of 98.2% by weight of HEMA and 1.8% by weight of NaMA and containing 0.5% by weight of ethylene glycol dimethacrylate with% by weight of glycerol. This mixture is polymerized with 0.5%, by weight based on the total amount of monomers, of benzol ethyl ether, for 15 minutes under ultraviolet radiation. The resulting material contains after swelling

  53% by weight of water, with G = 0.273 MPa.

Example 20

  80% by weight of a mixture consisting of 97.5% by weight of HEMA and 2.5% by weight of NaMA and containing 0.5% by weight of ethylene glycol dimethacrylate with% by weight are mixed at 80% by weight. glycerol. This mixture is polymerized with 0.5% by weight, based on the total amount of monomers, of benzoin ethyl ether for 15 minutes under ultraviolet radiation. The resulting material contains after swelling

  54.7% by weight of water, with G = 0.291 MPa.

Example 21

  A mixture composed of 97% by weight of HESIA and 3% by weight of NaMA and containing 0.5% by weight of ethylene glycol dimethacrylate with 20% by weight of glycerol is mixed at a rate of 80% by weight. . This mixture is polymerized with 0.5%, by weight relative to the total amount of monomers, of benzolene ethyl ether, for 15 minutes under radiation.

  ultraviolet. The resulting material after swelling contains 58.3% by weight of water, with G = 0.302 MPa.

Example 22

  A mixture composed of 98.7% by weight of HEMA and 1.3% by weight of potassium methacrylate and containing 0.5% by weight of ethylene glycol dimethacrylate is mixed at a rate of 70% by weight with 30% by weight. by weight of glycerol. This mixture is polymerized with 0.5% by weight, based on the total amount of monomers, of benzol ethyl ether for 15 minutes under ultraviolet radiation. The resulting material

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  after swelling 51.3% by weight of water, with G = 0.223 MPa. The linear expansion coefficients are K = 1.17 (for swelling in water) and Ks = 1.11 (for

  swelling in physiological solution).

Example 23

  70% by weight of a compound mixture is mixed

  of 98.2% by weight of HEMA and 1.8% by weight of NaMA and

  holding 0.5% by weight of ethylene glycol dimethacrylate with% by weight of glycerol. This mixture is polymerized with 0.5% by weight based on the total amount of monomers of benzol ethyl ether for 15 minutes under ultraviolet radiation. The resulting material contains after swelling 56.5% by weight of water, with G = 0.235 IPa, K = 1.21 and K = W S 1.13.

Example 24

  70% by weight of a mixture composed of 97.5% by weight of HEMA and 2.5% by weight of NaMA and containing 0.5% by weight of ethylene glycol dimethacrylate with% by weight of glycerol. This mixture is polymerized with 0.5%, based on the total amount of benzolene ethyl ether monomers, for 15 minutes under ultraviolet radiation. The resulting material contains after swelling 59.5% by weight of water, with G = 0.251 MPa, K = 1.25 and K = W s 1.16.

Example 25

  70% by weight of a mixture composed of 97% by weight of HE 3 MA and 3% by weight of NaIA and containing 0.5% by weight of ethylene glycol dimethacrylate with 30% by weight of glycerol is mixed at a rate of 70% by weight. . This mixture is polymerized with 0.5% by weight, based on the total amount of monomers, of benzoin ethyl ether for 15 minutes under ultraviolet radiation. The resulting material after swelling contains 61.9% by weight of water, with G = 0.261} Pa, K = 1.29 and K = W s 1.18.

Example 26

  A mixture composed of 98.7% by weight of HEMA and 1.3% by weight of NaMA and containing 0.5% by weight of ethylene glycol dimethacrylate is mixed at a rate of 60% by weight with 11% by weight. glycerol. This mixture is polymerized with 0.5% by weight, based on the total amount of monomers, of benzol ethyl ether for 15 minutes under ultraviolet radiation. The resulting material after swelling contains 53% by weight of water, with G = 0, 190 MPa, K = 1.12 and K = w s 1.06.

Example 27

  60% by weight of a mixture composed of 98.2% by weight of HEMA and 1.8% by weight of NaMA and containing 0.5% by weight of ethylene glycol dimethacrylate with% by weight are mixed at a rate of 60% by weight. glycerol. This mixture is polymerized with 0.5% by weight, based on the total amount of monomers, of benzoin ethyl ether for 15 minutes under ultraviolet radiation. The resulting material after swelling contains 56.5% by weight of water, with G = 0.199 Pa, Kw = 1.17 and K = 0.09 wt = 0.78.

Example 28

  60% by weight of a mixture composed of 97.5% by weight of HEMA and 2.5% by weight of NaMA and containing 0.5% by weight of ethylene glycol dimethacrylate with% by weight are mixed at a rate of 60% by weight. glycerol. This mixture is polymerized with 0.5% by weight, based on the total amount of monomers, of benzoin ethyl ether for 15 minutes under ultraviolet radiation. The resulting material after swelling contains 60.2% by weight of water, with G = 0.215 MPa, K = 1.21 and K = w s 1.11.

Example 29

  A mixture consisting of 97% by weight of HEMA and 3% by weight of NaMA and containing 0.5% by weight of ethylene glycol dimethacrylate with 40% by weight of the mixture is mixed at a rate of 60% by weight. glycerol. This mixture is polymerized with 0.5% by weight, based on the total amount of monomers, of benzolene ethyl ether, for 15 minutes under ultraviolet radiation. The resulting material contains after swelling 65.5% by weight of water, with G = 0.229 MPa, Kw = 1.25 and Ks = 1.14.

Example 30

  90% by weight of a compound mixture is mixed

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  69.5% by weight of HEMA, 0.5% by weight of NaMA and 30% by weight of DEGMA and containing 0.3% by weight of ethylene glycol dimethacrylate and 0.3% by weight of diethylene glycol dimethacrylate with 10% by weight of glycerol. This mixture is polymerized with 0.5% by weight based on the total amount of monomers of benzoin ethyl ether for 15 minutes under ultraviolet radiation. The resulting material contains after swelling 49.1% by weight of water, with G =

0.169 MPa.

Example 31

  90% by weight of a mixture consisting of 69.3% by weight of HEMA, 0.7% by weight of NaMA and% by weight of DEGMA and containing 0.3% by weight of 6thylenebis is mixed at a rate of 90% by weight acrylamide and 0.2% by weight of diethylene glycol dimethacrylate with 10% by weight of glycerol. This mixture is polymerized with 0.5%, by weight based on the total amount of monomers, of benzol ethyl ether for 15 minutes under ultraviolet radiation. The resulting material contains after swelling 51.4% by weight of water, with G = 0.174 MPa. Example 32 90% by weight of a mixture of 69.1% by weight of HEMA, 0.9% by weight of NaIA and% by weight of DEGMA and containing 0.3% by weight are mixed at 90% by weight ethylene glycol dimethacrylate and 0.3% by weight diethylene glycol dimethacrylate with 10% by weight diacetin. This mixture is polymerized with 0.5%, by weight based on the total amount of monomers, of benzol ethyl ether, for 15 minutes under ultraviolet radiation. The resulting material contains after swelling 54.6% water, with G = 0.182 MPa. EXAMPLE 33 80% by weight of a mixture of 69.9% by weight of HEMA, 0.1% by weight of NaXA and% by weight of DEGMA, containing 0.3% by weight are mixed at 80% by weight. ethylene glycol dimethacrylate and 0.3% by weight of diethylene glycol dimethacrylate, with 20% by weight of glycerol. We polymerize

  this mixture with 0.5%, by weight based on the total amount of benzol ethyl ether monomers, for 15 minutes under ultraviolet radiation. The resulting material con-

  after swelling 49.6% by weight of water with G = 0.139 MPa.

Example 34

  A mixture composed of 69.7% by weight of HEMA, 0.3% by weight of NaMA and 30% by weight of DEGMA and containing 0.3% by weight of ethylene is mixed at 80% by weight. glycol dimethacrylate and 0.3% by weight of diethylene glycol dimethacrylate with 20% by weight of dimethylsulfoxide. This mixture is polymerized with 0.5% by weight, based on the total amount of monomers, of benzoin ethyl ether for 15 minutes under ultraviolet radiation. The resulting material contains after swelling 49.6% by weight of water, with G = 0.142} Pa.

Example 35

  A mixture composed of 69.5% by weight of HEMA, 0.5% by weight of NaMA and% by weight of DEGMA and containing 0.3% by weight is mixed at 80% by weight. ethylene glycol dimethacrylate and 0.3% by weight of diethylene glycol dimethacrylate with 20% by weight of glycerol. This mixture is polymerized with 0.5% by weight based on the total amount of monomers of benzol ethyl ether for 15 minutes under ultraviolet radiation. The resulting material contains after swelling 51.3% by weight of water, with G = 0.147 MIao

Example 36

  A mixture composed of 69.3% by weight of HEMA, 0.7% by weight of NaYA and% by weight of DEGMA and containing 0.3% by weight of ethylene is mixed at 80% by weight. glycol dimethacrylate and 0.3% by weight of diethylene glycol dimethacrylate with 20% by weight of glycerol. The mixture is polymerized with 0.5%, by weight based on the total amount of monomers, of benzol ethyl ether for 15 minutes under ultraviolet radiation. The resulting material contains after swelling 53.4% by weight of water, with G = 0.153 Pa.

Example 37

  80% by weight of a mixture consisting of 69.1% by weight of HEMA, 0.9% by weight of NaMA and% by weight of DEGMA and containing 0.3% by weight of ethylene are mixed at a rate of 80% by weight

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  glycol dimethacrylate and 0.3% by weight of diethylene glycol dimethacrylate with 20% by weight of glycerol. This mixture was polymerized with 0.5% by weight based on the total amount of monomers of benzoin ethyl ether for 15 minutes under ultraviolet radiation. The resulting material after swelling 58.8% w / w water, with G = 0.161 MPa.

Example 38

  70% by weight of a mixture composed of 69.9% by weight of HEMA, 0.1% by weight of NaMA and 30% by weight of DEGMA and containing 0.3% by weight are mixed at 70% by weight. ethylene-bisacrylamide and 0.2% by weight of diethylene glycol dimethacrylate with 30% by weight of dimethylsulfoxide. This mixture was polymerized with 0.5% by weight based on the total amount of monomers of benzol ethyl ether for 15 minutes under ultraviolet radiation. The resulting material contains after swelling 50.1% by weight of water, with G = 0.121

iPa, K = 1.13 and K = 1.11.

W S

Example 39

  70% by weight of HEMA, 0.3% by weight of NaMA and 30% by weight of DEGMA and containing 0.3% by weight are mixed at a rate of 70% by weight. weight of ethylene glycol dimethacrylate and 0.3% by weight of diethylene glycol dimethacrylate with 30% by weight of glycerol. This mixture is polymerized with 0.5% by weight based on the total amount of monomers of benzol ethyl ether for 15 minutes under ultraviolet radiation. The resulting material contains after swelling 50.7% by weight of water, with G = 0.125 MPa,

K = 1.15 and K = 1.12.

Example 40

  70% by weight of a mixture composed of 69.5% by weight of HEMA, 0.5% by weight of NaMA and 30% by weight of DEGMA and containing 0.3% by weight of ethylene glycol dimethacrylate and 0.3% by weight of diethylene glycol dimethacrylate with 30% by weight of glycerol. We polymerize

  this mixture with 0.5%, by weight relative to the total amount of monomers, of benzoin ethyl ether, for 15 minutes under ultraviolet radiation. The resulting material con-

  holds after swelling 54.2% by weight of water, with G = 0.129

MPa, K = 1.18 and K = 1.14.

  EXAMPLE 41 70% by weight of a mixture composed of 69.3% by weight of HEXA, 0.7% by weight of NaMA and 30% by weight of DEGMA and containing 0.3% by weight are mixed. weight of ethylene glycol dimethacrylate and 0.3% by weight of diethylene glycol dimethacrylate with 30% by weight of glycerol. This mixture was polymerized with 0.5% by weight based on the total amount of monomers of benzoin ethyl ether for 15 minutes under ultraviolet radiation. The resulting material contains after swelling 55.3% by weight of water, with G = 0.135

MPa, K = 1.22 and K = 1.15.

W s

Example 42

  70% by weight of a mixture composed of 69.1% by weight of HEMA, 0.9% by weight of NaMA and 30% by weight of DEGMA and containing 0.3% by weight of ethylene glycol dimethacrylate and 0.3% by weight of diethylene glycol dimethacrylate with 30% by weight of glycerol. This mixture is polymerized with 0.5% by weight based on the total amount of monomers of benzol ethyl ether for 15 minutes under ultraviolet radiation. The resulting material contains after swelling 61.3% by weight of water, with G = 0.139

MPa, K = 1.23 and K = 1.16.

W s

Example 43

  60% by weight of a mixture composed of 69.9% by weight of HEMA, 0.1% by weight of NaMA and 30% by weight of DEGMA and containing 0.3% by weight of ethylene glycol dimethacrylate and 0.3% by weight of diethylene glycol dimethacrylate with 40% by weight of glycerol. This mixture is polymerized with 0.5%, by weight relative to the total amount

  of monomers, benzol ethyl ether, for 15 minutes under ultraviolet radiation. The resulting material after swelling contains 51.8% by weight of water, with G = 0.103 MPa, K = 1.10 and K = 1.08.

Example 44

  A mixture consisting of 69.7% by weight of HEMA, 0.3% by weight of NaMA and 305% by weight of DEGMA containing 0.3% by weight is mixed at 60% by weight. ethylene glycol dimethacrylate and 0.3% by weight of diethylene glycol dimethacrylate with 40% by weight of glycerol. This mixture was polymerized with 0.5% by weight based on the total amount of benzoin ethyl ether monomers for 15 minutes under ultraviolet radiation. The resulting material contains after swelling 51.8% by weight of water, with G = 0.108 MPa,

K = 1.11 and K = 1;

w s

Example 45

  A mixture composed of 69.5% by weight of HEMA, 0.5% by weight of NaMA and 30% by weight of DEGMA and containing 0.3% by weight of 60% by weight is blended. ethylene glycol dimethacrylate with 40% by weight of glycerol. This mixture was polymerized with 0.5% by weight based on the total amount of monomers of benzol ethyl ether for minutes under ultraviolet radiation. The resulting material contains after swelling 58.9% by weight of water, with

  G = 0.121 XPa, K = 1.15 and K = 1.10.

w s

Example 46

  A mixture composed of 69.3% by weight of HEMA, 0.7% by weight of NaSA and 30% by weight of DEGWA and containing 0.3% is mixed at 60% by weight. by weight of ethylene glycol dimethacrylate and 0.3% by weight of diethylene glycol dimethacrylate with 40% by weight of glycerol. This mixture was polymerized with 0.5%, by weight based on the total amount of monomers, of benzol ethyl ether, for 15 minutes under ultraviolet radiation. The resulting material contains after swelling 61.3% by weight of water, with G = 0.114

MPa, K = 1.17 and K = 1.11.

w s

Example 47

  60% by weight of a mixture composed of 69.1% by weight of HEMA, 0.9% by weight of NaXA and 30% by weight of DEGMA and containing 0.3% by weight of ethylene glycol dimethacrylate and 0.3% by weight of diethylene glycol dimethacrylate with 40% by weight of glycerol. This mixture is polymerized with 0.5% by weight, based on the total amount of monomers, of benzoin ethyl ether for 15 minutes under ultraviolet radiation. The resulting material

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  contains after swelling 64.9% by weight of water, with G =

0.118 MPa, K = 1.23 and K = 1.12.

w S

Example 48

  A mixture consisting of 97.5% by weight of HEMA and 2.5% by weight of NaMA and containing 0.2% by weight of ethylene glycol dimethacrylate is mixed at 70% by weight with by weight of glycerol. This mixture is polymerized with 0.5% by weight, based on the total amount of monomers, of benzoin ethyl ether for 15 minutes under ultraviolet radiation. The resulting material contains after swelling

  1% by weight of water, with G = 0.242 MPa.

Example 49

  A mixture composed of 97.5%, HEMA and 2.5% by weight of NaXA and containing 0.7% by weight of ethylene glycol dimethacrylate and 0.4% by weight is mixed at 70% by weight. by weight of diethylene glycol dimethacrylate with 30% by weight of glycerol. This mixture is polymerized with 0.5% by weight, based on the total amount of monomers, of benzoin ethyl ether for 15 minutes under ultraviolet radiation. The resulting material contains after swelling 59.2%

weight of water, with G = 0.266 MPa.

Example 50

  70% by weight of a mixture composed of 69.5% by weight of HEMA, 0.5% by weight of potassium methacrylate and 30% by weight of DEGMA and containing 0.2% by weight are mixed at 70% by weight. by weight of ethylene glycol dimethacrylate with 30% by weight of glycerol. This mixture is polymerized with 0.5% by weight based on the total amount of monomers of benzol ethyl ether for 15 minutes under ultraviolet radiation. The resulting material contains after swelling 55% by weight.

of water, with G = 0.118 MPa.

Example 51

  70% by weight of a mixture composed of 69.5% by weight of HEMA, 0.5% by weight of NaNA and 3056% by weight of DEGMA and containing 0.7% by weight of ethylene glycol dimethacrylate and 0.4% by weight of diethylene glycol dimethacrylate with 30% by weight of glycerol. This mixture is polymerized with 0.5% by weight relative to the total amount

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  of monomers, benzoin ethyl ether, for 15 minutes under ultraviolet radiation. The resulting material contains after swelling 53.7% by weight of water, with G = 0.140 MPa

Example 52

  A mixture composed of 97.5% by weight of HEMA and 2.5% by weight of NaMA and containing 0.5% by weight of ethylene glycol dimethacrylate with% by weight of glycerol is mixed at a rate of 70% by weight. . This mixture is polymerized with 0.2%, by weight relative to the total amount of monomers, azobisisobutyronitrile, for 16 hours at 600C. The resulting material contains after swelling 59.5% by weight of water, with

G = 0.250 MPa.

Example 53

  70% by weight of a mixture composed of 97.5% by weight of HEMA and 2.5% by weight of NaMA and containing 0.5% by weight of ethylene glycol dimethacrylate with% by weight of glycerol is mixed at a rate of 70% by weight. The mixture is polymerized with 0.1% by weight, based on the total amount of monomers, of diisopropyl peroxocarbonate, for 16 hours at 600 ° C. The resulting material contains after swelling 59.4% by weight of water,

with G = 0.251 MPa.

Example 54

  A mixture consisting of 97.5% by weight of HEMA and 2.5% by weight of NaMA and containing 0.5% by weight of ethylene glycol dimethacrylate with% by weight is mixed at a rate of 70% by weight. glycerol. This mixture is polymerized with 0.25, by weight relative to the total amount of ammonium persulfate monomers, for 1 hour at 780C. The resulting material contains after swelling 59.4% by weight of water, with

G = 0.253 MPa.

Example 55

  A mixture consisting of 97.5% by weight of HEMA and 2.5% by weight of NaMA and containing 0.5% by weight of ethylene glycol dimethacrylate with 30% by weight is mixed at a rate of 70% by weight. glycerol. This mixture is polymerized with 0.5%, by weight relative to the total amount of monomers, of benzoin ethyl ether, for 15 minutes under radiation.

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  ultraviolet. The resulting material contains after swelling

  59.3% by weight of water, with G = 0.252 MPa.

Example 56

  A mixture composed of 69.5% by weight of HEMA, 0.5% by weight of NaMA and 30% by weight of DEGMA and containing 0.3% by weight is mixed at 70% by weight. ethylene glycol dimethacrylate and 0.3% by weight of diethylene glycol dimethacrylate with 30% by weight of glycerol. This mixture was polymerized with 0.2%, by weight based on the total amount of monomers, azobisisobutyronitrile, for 16 hours at 600 ° C. The resulting material contains after swelling 54%

water weight, with G = 0.130 MPa.

Example 57

  A mixture composed of 69.5% by weight of HEMA, 0.5% by weight of NaMA and 30% by weight of DEGMA and containing 0.3% by weight is mixed at 70% by weight. weight of ethylene glycol dimethacrylate and 0.3% by weight of diethylene glycol dimethacrylate with 30% by weight of glycerol. The mixture is polymerized with 0.1% by weight based on the total amount of monomers of diisopropyl peroxocarbonate for 16 hours at 600 ° C. The resulting material contains after swelling

  54.3% by weight of water, with G = 0.128 MPa.

Example 58

  70% by weight of a mixture composed of 69.5% by weight of HEMA, 0.5% by weight of NaNA and 30% by weight of DEGMA and containing 0.3% is mixed. by weight of ethylene glycol dimethacrylate and 0.3% by weight of diethylene glycol dimethacrylate with 30% by weight of glycerol. The mixture is polymerized with 0.2% by weight, based on the total amount of monomers, of persulfate. ammonium for 1 hour at 78 ° C. The resulting material contains after swelling 54.1%

by weight of water, with G = 0.131 MPa.

Example 59

  70% by weight of a mixture composed of 69.5% by weight of HEMA, 0.5% by weight of NaMA and 30% by weight of DEGMA and containing 0.3% by weight of ethylene glycol dimethacrylate and 0.3% by weight of diethylene glycol dimethacrylate with 30% by weight of glycerol. This mixture is polymerized with 0.5% by weight, based on the total amount of monomers, of benzol methyl ether for 15 minutes under ultraviolet radiation. The resulting material contains after swelling 54.2% by weight of water, with G = 0.129 MPa.

Example 60

  A mixture composed of 69.5% by weight of HEMA, 0.5% by weight of NaMA and 30% by weight of DEGMA and containing 4% by weight of triethylene is mixed at 60% by weight.

  glycol dimethacrylate with 40% by weight of glycerol. This mixture was polymerized with 0.5% by weight based on the total amount of monomers of benzol isopropyl ether for 15 minutes under ultraviolet radiation. The resulting material contains after swelling 51% by weight of water, with 15 G = 0.19 MPa.

Example 61

  70% by weight of a mixture composed of 91% by weight of HMM and 9% by weight of NaMA and containing 0.5% by weight of ethylene glycol dimethacrylate with 30% by weight are mixed at a rate of 70% by weight. glycerol. The mixture is polymerized with 0.5% by weight based on the total amount of monomers of benzol methyl ether for 15 minutes under ultraviolet radiation. The resulting material contains after swelling

% by weight of water.

Example 62

  70% by weight of a mixture composed of 49.75% by weight of HEMA, 50% by weight of DEGNA and 0.25% by weight of NaMA and containing 0.3% by weight of ethylene glycol dimethacrylate and 0.3% by weight of diethylene glycol dimethacrylate with 30% by weight of glycerol. This mixture is polymerized with 0.5% by weight, based on the total amount of benzoin ethyl ether monomers, for 15 minutes under ultraviolet radiation. The resulting material contains after swelling 61.5% by weight of water. EXAMPLE 63 90% by weight of a mixture composed of 97.5% by weight of HEbMA and 2.5% by weight of methacrylate is mixed.

  of ammonium and containing 0.5% by weight of ethylene glycol di-

  methacrylate with 10% by weight of glycerol. This mixture is polymerized with 0.5% by weight, based on the total amount of monomers, of benzolene ethyl ether, for 15 minutes under ultraviolet radiation. The resulting material contains after swelling 56% by weight of water, with G = 0.295 MPa.

Example 64

  A mixture composed of 98.7% by weight of HEMA and 1.3% by weight of sodium acrylate and containing 0.5% by weight of ethylene glycol dimethacrylate is mixed at 80% by weight with 20% by weight of glyceryl. This mixture is polymerized with 0.5%, by weight based on the total amount of monomers, of benzol ethyl ether for 15 minutes under ultraviolet radiation. The resulting material contains after swelling 53% by weight of water, with G = 0.26 IPa. EXAMPLE 65 A mixture composed of 98.7% by weight of HEMA and 1.3% by weight of potassium acrylate and containing 0.5% by weight of ethylene is mixed at 80% by weight. glycol dimethacrylate with 20% by weight of glycerol. The mixture is polymerized with 0.5% by weight, based on the total amount of monomers, of benzol ethyl ether for 15 minutes under ultraviolet radiation. The resulting material contains

  after swelling 52.5% by weight of water, with G = 0.26 MPa.

Example 66

  90% by weight of a mixture composed of 97% by weight of HE} A and 3% by weight of methacrylic acid and containing 0.5% by weight of ethylene glycol dimethacrylate with 10% by weight of glycerol. This mixture is polymerized with 0.5%, by weight based on the total amount of monomers, benzol ethyl ether, between a glass plate and a poly (tetrafluoroethylene) plate for 15 minutes under ultraviolet radiation. The resulting film is conditioned in an alcoholic solution of hydroxide

  sodium, and then washed with distilled water. The gonfied film contains 56% by weight of water, with G = 0.3 MPa.

Example 67

  The film prepared according to Example 66 is conditioned in an aqueous solution of ammonium hydroxide, and then

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* lava with distilled water. This film contains in the state

  inflated 60.3% by weight of water, with G = 0.3 MPa.

Example 68

  A mixture composed of 97% by weight of HEMA and 3% by weight of acrylic acid and containing 0.5% by weight of ethylene glycol dimethacrylate with 10% by weight is mixed at 90% by weight. glycerol. A film is prepared from this mixture in the same manner as in Example 66. This film is subjected to packaging in an alcoholic solution of sodium hydroxide, followed by

  washed with distilled water and subjected to measurement. The water content is 61% by weight, with G = 0.295 MPa.

Example 69

  The film prepared according to Example 68 was subjected to conditioning in an alcoholic solution of potassium hydroxide and then washed with distilled water. The results

  are similar to those in Example 68.

Example 70

  A mixture of 95% by weight of HEMA and 5% by weight of methacrylic acid and containing 0.5% by weight of ethylene glycol dimethacrylate is mixed at 80% by weight with 20% by weight. glycerol weight. This mixture is polymerized with 0.5% by weight, based on the total amount of monomers, of benzoin ethyl ether for 15 minutes under ultraviolet radiation. The resulting material contains after

swelling 42% by weight of water.

Example 71

  80% by weight of a mixture consisting of 95% by weight of HEMA and 5% by weight of acrylic acid and containing 0.5% by weight of ethylene glycol dimethacrylate is mixed with 20% by weight of glycerol. This mixture is polymerized with 0.5%, by weight, based on the total amount of monomers,

  of ethyl benzol ether for 15 minutes under ultraviolet radiation. The resulting material contains after swelling 45% by weight of water.

  The copolymers according to the invention have mechanical characteristics which are clearly superior to those of the copolymer

r

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  DEGMA reticulated and often comparable to those of the EIAA, which are still suitable for the applications according to the invention. The copolymers according to the invention are substantially free of water-soluble extracts and provide a sufficiently high water balance content in the resulting gel, with adequate optical and mechanical characteristics, so that they can be used. to the

  manufacture of contact lenses for permanent wear.

Claims (11)

  1. Hydrophilic copolymer characterized in that it can be prepared by copolymerization of a mixture of monomers of 2-hydroxyethyl methacrylate and 2- (2-hydroxyethoxy) ethyl methacrylate, in a proportion of 90 to 99.99% by weight, with free methacrylic or acrylic acids or with their sodium, potassium and ammonium salts in an amount of 10 to 0.01% by weight in the presence of radical initiators, the monomer mixture of 2 hydroxyethyl methacrylate and 10 -2 (2-hydroxyethoxy) ethyl methacrylate containing 0 to 50% by weight of 2- (2-hydroxyethoxy) ethyl methacrylate and the total monomer mixture containing 0.01 to 4% by weight of a   crosslinking agent comprising at least two olefinic double bonds.   Hydrophilic copolymer according to claim 1,   characterized in that the crosslinking agent is selected from multifunctional esters or amides of acrylic acid or methacrylic acid.   Hydrophilic copolymer according to claim 1 or 2, characterized in that the radical initiators are   selected from azole compounds, peroxides, peroxocarbonates, persulfates, photoinitiators based on ethers of   benzoin and their derivatives, and initiation redox systems, such as persulfate-metabisulfite, persulfaleallylamine and benzoylealkylamine peroxide systems.   4. Hydrophilic copolymer according to any one of   Claims 1 to 3, characterized in that the copolymerization is carried out in the presence of polar solvents, such as glycerol, glycols and their derivatives,   water, dimethylformamide, dimethylsulfoxide, dimethylacetamide, diacetin, isopropanol or mixtures thereof.   Hydrophilic copolymer according to one of Claims 1 to 4, characterized in that the ratio of   solvent to the monomer mixture is between 1/99 to 50/50 (percent).   6. Process for the preparation of the hydrophilic copolymer according to any one of Claims 1 to 5, characterized   in that a monomer mixture of 2-hydroxyethyl methacrylate and 2- (2-hydroxyethoxy) ethyl methacrylate is polymerized at 90 to 99.99% by weight with sodium, potassium or ammonium salts. methacrylic acid or acrylic acid in a proportion of 10 to 0.01% by weight and in the presence of radical initiators and in the presence of 0.01 to 4%, by weight relative to the total of mixture of monomers, a crosslinking agent comprising at least two olefinic double bonds, the content of 2- (2-hydroxyethoxy) ethyl methacrylate of the monomer mixture of 2-hydroxyethyl methacrylate and 2- (2-hydroxyethoxy) ethyl methacrylate being of 0 to 50% by weight.   7. Process for preparing the hydrophilic copolymer according to   any one of claims 1 to 5, characterized in that copolymerizes a mixture of monomers of 2-hydroxyethyl   methacrylate and 2- (2-hydroxyethoxy) ethyl methacrylate, 90 to 99.99% by weight, with sodium, potassium or ammonium salts of methacrylic acid or acrylic acid, from 10 to 0.01% by weight, in the presence of radical initiators and in the presence of 0.01 to 4%, by weight, based on the entire monomer mixture, of a crosslinking agent comprising at least two olefinic double bonds, the content of 2- (2-hydroxyethoxy) ethyl methacrylate of the monomer mixture of 1-hydroxyethyl methacrylate and 2- (2-hydroxyethoxy) ethyl methacrylate being from 0 to 50% by weight. 8. Process according to claim 6, characterized in that the copolymer prepared in aqueous or alcoholic solutions of sodium hydroxide, potassium hydroxide or ammonium hydroxide or salts thereof with weak acids is conditioned, then   it is washed, preferably with distilled water.   9. Process according to any one of Claims 6 to 8, characterized in that the copolymerization is carried out in   presence of a polar solvent or a mixture of polar solvents.   10. Process according to any one of claims 6 to 9, characterized in that the solvent, or also the low molecular weight fractions soluble in water, present in the crosslinked copolymer, are extracted with water, and then   reduces the copolymer by drying to a constant weight.   11. Process according to any one of the claims   6 to 10, characterized in that the drying is carried out in a saturated vapor medium at a temperature above that of the glass transition, Tg, of the copolymer prepared.