Method of making formpieces, formpiece made thereby, prepolymers suitable for use according to said method, network polymers, homo- or copolymers obtained from such prepolymers, method of obtaining said prepolymers and network polymers, homo- or copolymers obtained from them,l formpieces made of said homo- or copolymers and method of making said formpieces using homo- or copolymers

The present invention relates to new prepolymers which are used for the production of shaped bodies, especially contact lenses. In particular, these prepolymers are such polyvinyl alcohol derivatives that contain cyclic acetyl groups and crosslinkable groups.

Cross-linkable prepolymers derived from polyvinyl alcohol are already known. For example, EP 216 074 discloses contact lenses that contain polyvinyl alcohol that has (meth) acryloyl groups associated with urethane groups. EP 189 375 describes contact lenses of polyvinyl alcohol crosslinked with polyepoxides.

In addition, certain special acetals that contain crosslinkable groups are already known. In this connection, reference should be made to the documents EP 201 693, EP 215 245 and EP 211 432, for example. The document EP 201 693 describes, among others, acetals of unbranched aldehydes with 2-11 carbon atoms, which have an amino group in the final position amine is substituted with a C3-C unsaturated organic radical₂4 olefin. This organic radical causes the attraction of electrons of the nitrogen atom, and in addition the presence of unsaturated olefin bond causes the ability to polymerize. EP 201 693 also generally discusses the reaction products of the acetals with 1,2-diol, 1,3-diol, polyvinyl alcohol or cellulose characterized above; such products are not specifically disclosed.

If in EP 201 693 reference is made to any of the acetals in connection with polyvinyl alcohol, as is the case in example 17 of this patent application, then this polymer capable of polymerization due to its olefinic group is first copolymerized, for example with vinyl acetate. The copolymer obtained in this way is then processed into polyvinyl alcohol; an emulsion is formed containing 37% solids with a pH value of 5.43 and a viscosity of 11 640 mPa · s.

The present invention relates to prepolymers that contain a basic 1,3-diol backbone, wherein a certain percentage of the 1,3-diol units are modified to 1,3-dioxane which has a polymerizable but non-polymerized radical in position 2. The polymerizable radical is especially the aminoalkyl radical to which the polymerizable group is attached.

The prepolymer, which is a derivative of polyvinyl alcohol with a molecular weight of at least 2000, according to the invention is characterized in that it contains from 0.5 to 80%, with respect to the number of polyvinyl alcohol hydroxyl groups, of the formula (I) in which

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R is alkylene with a maximum of 6 carbon atoms, R¹ is hydrogen or alkyl with 1 to 4 carbon atoms, R² is an unsaturated olefinic acyl residue of formula R³-CO-, in which R³ is alkenyl with 2 to 4 carbon atoms.

Preferably, the prepolymer comprises units of formula 1, wherein R is alkylene with 1 to 4 carbon atoms and R1 is hydrogen.

Particularly preferably, the prepolymer comprises units of the formula I in which R is methylene and butylene.

Preferably, the prepolymer contains from 1 to 15%, based on the number of polyvinyl alcohol hydroxyl groups, of the units of formula 1.

R1 is preferably hydrogen.

The unsaturated, olefinic, copolymerizable radical R3 is, for example, ethenyl, 2-propenyl, 3-propenyl, 2-butenyl. Ethenyl and 2-propenyl are preferably such that the -CO-R3 group is the acyl residue of acrylic or methacrylic acid.

The prepolymers of the invention are polyvinyl alcohol derivatives with a molecular weight of at least 2000, containing from 0.5 to 80%, based on the number of hydroxyl groups of the polyvinyl alcohol, structural units of formula 1, especially 1-50%, preferably 1-25%, still more preferably 2-15%, particularly preferably 3-10%. The prepolymers of the invention, which are intended for the production of contact lenses, contain in particular from 0.5 to 25%, based on the number of polyvinyl alcohol hydroxyl groups, structural units of the formula 1, especially 1-15%, particularly preferably 2-12% .

The polyvinyl alcohols from which the derivatives of the invention can be prepared have preferably a molecular weight of at least 10,000. The upper value of the molecular weight of polyvinyl alcohols can be up to 1,000,000. Preferably, the polyvinyl alcohols have a molecular weight of up to 300,000, especially up to 100,000, and particularly preferably up to 50,000.

The polyvinyl alcohols used generally have a poly (2-hydroxy) ethylene structure. The polyvinyl alcohol derivatives according to the invention may, however, also have hydroxy groups in the form of 1,2-glycols such as 1,2-dihydroxyethylene copolymer units which can be obtained, for example, by alkaline hydrolysis of a vinyl acetate copolymer with vinyl carbonate.

In addition, the polyvinyl alcohol derivatives of the invention may also contain a small amount, for example up to 20%, preferably up to 5%, of copolymer units of ethylene, propylene, acrylamide, methacrylamide, dimethacrylamide, hydroxyethyl methacrylate, methyl methacrylate, methyl acrylate, ethyl acrylate, pyrrolidone hydroxyethyl, allyl alcohol, styrene or similar commonly used comonomers

Commercially available polyvinyl alcohols may be used, such as, for example, Vinol® 107 from Air Products (molecular weight = 2,000-3,000, 98-98.8% hydrolyzed, Polysciences 4397 (molecular weight = 2,500, 98.5 hydrolyzed %), BF 14 from Chan Chun, Elvanol® from Du Pont, UF-120 from Unitika, Moviol® 4-88, 10-98 and 20-98 from Hoechst. Other manufacturers are, for example, Nippon Gohsei (Gohsenol®), Monsanto (Gelvatol®), Wacker (Polyviol® or Japanese producers Kuraray, Denki and Shin-Etsu.

Polyvinyl alcohol is usually prepared by hydrolysis of the corresponding homopolymer polyvinyl acetate. Preferably, the polyvinyl alcohol derivative of the invention contains less than 50% polyvinyl acetate units, especially less than 20% polyvinyl acetate units. Preferred amounts of residual acetate units in the polyvinyl alcohol derivative of the invention with respect to the sum of vinyl alcohol units and acetate units are approximately 3-20%, more preferably 5-16%, especially 10-14%.

Compounds containing structural units of Formula 1 can be prepared in a known manner. For example, polyvinyl alcohol with a molecular weight of at least 2,000, which contains the structural units of formula 2 in an amount of 0.5-80%, with respect to the number of hydroxyl groups in the compound of formula 2, can be converted (especially in an acid medium) to a compound of of formula 3, wherein R 'and R, independently of each other, represent hydrogen, low alkyl or low alkanoyl, such as acetyl or propionyl, and the other substituents have the meanings given in formula 1

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Alternatively, polyvinyl alcohol with a molecular weight of at least 2000, which contains structural units of formula 2, can be converted (especially under acidic conditions) with a compound of formula 4 in which the substituents are as defined for a compound of formula 3 and thus obtained the cyclic acetal can then be converted with a compound of formula 5 in which R³ is e.g. alkenyl with 2-4 carbon atoms and X is a reactive group, e.g. an etherified or esterified hydroxy group, e.g. a halogen, especially chlorine.

Compounds of formula 3 are known, for example from document EP 201 693. Also described are compounds of formula 4.

Compounds of formula 5 are known and their typical representative is methacryloyl chloride.

Surprisingly, it was found that the prepolymers of Formula 1 are extremely stable. This is surprising for a skilled person, because acrylates with higher functional groups usually need to be stabilized. If compounds of this type are not stabilized, polymerization usually occurs quickly. However, the prepolymer according to the invention does not undergo spontaneous crosslinking by homopolymerization. The prepolymers of formula I can furthermore be purified in a known manner, for example by acetone precipitation, dialysis or ultrafiltration, with ultrafiltration being particularly preferred. By such purification operations, the prepolymers of formula 1 can be obtained in extremely pure form, e.g. as concentrated aqueous solutions which are free or at least substantially free of reaction products such as salts and starting materials such as e.g. compounds of formula 3 or other non-polymer components.

The preferred method of purifying the prepolymer of the invention, ultrafiltration, can be carried out in a known manner. Here, it is possible to carry out ultrafiltration repeatedly, for example 2 to 10 times. Alternatively, ultrafiltration can also be carried out continuously until the desired degree of purity is reached. The desired degree of purity can generally be chosen as high as you like. A suitable measure of the degree of purity is, for example, the sodium chloride content of the solution, which can easily be determined in a known manner.

The prepolymers according to the invention of the formula I are crosslinked in an extremely effective manner and intentionally, especially by photocrosslinking, in the absence or presence of additional vinyl comonomers. The polymers formed are insoluble in water.

In photo-crosslinking, a photoinitiator is added, which can initiate radical crosslinking. Examples of this are known to those skilled in the art, in particular, benzinomethyl ether, 1-hydroxycyclohexylphenyl ketone, Daracure 1173 [2-hydroxyprop-2-yl-phenon] or Irgacure 2959 [4 '((3-hydroxyethoxy) -2-hydroxypropyl) 2-yl-phenone]. Cross-linking can then be triggered by photochemical radiation such as, for example, ultraviolet radiation or by ionizing radiation, such as, for example, gamma radiation or X-rays.

The photopolymerization is preferably carried out in a solvent. Suitable solvents are in principle all solvents that dissolve polyvinyl alcohol and optionally additional vinyl comonomers, e.g. water, alcohols such as low alkanols, e.g. ethanol or methanol, in addition carbonic acid amides such as dimethylformamide or dimethyl sulfoxide, and mixtures of suitable solvents , e.g. mixtures of water and alcohol, e.g. a mixture of water and ethanol and a mixture of water and methanol.

Photocrosslinking preferably takes place directly from the aqueous solution of the prepolymer according to the invention, which can be obtained by a favorable purification, ultrafiltration operation, optionally after the addition of an additional vinyl comonomer. For example, photo-crosslinking of approximately 15-40% aqueous solution can be carried out.

The process for producing polymers is characterized, for example, by photocrosslinking of the prepolymer containing the structural units of formula 1, especially in substantially pure form, i.e., e.g. after single or multiple ultrafiltration, preferably in solution, especially in aqueous solution, in the presence or absence of additional vinyl comonomers.

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The vinyl comonomer, which can additionally be used for photocrosslinking, can be a vinyl hydrophilic or hydrophobic monomer, or a mixture of vinyl, hydrophobic and hydrophyte monomers. Suitable vinyl monomers will include, in particular, those usually used in the production of contact lenses. By hydrophilic vinyl monomer is meant a monomer that typically gives a polymer which is water-soluble or can absorb at least 10% by weight of water as a homopolymer. Similarly, by hydrophobic vinyl monomer is meant a monomer that as a homopolymer typically results in a polymer which is insoluble in water or can absorb less than 10% by weight of water.

In general, approximately 0.01-80 units of a typical vinyl comonomer reacts with a structural unit of Formula 1.

If a vinyl comonomer is used, the crosslinked polymers preferably contain 1-15%, particularly preferably 3-8%, of structural units of formula 1, based on the number of polyvinyl alcohol hydroxyl groups that are converted with 0.1-80 vinyl monomer units.

The proportion of vinyl comonomers, if used, is preferably 0.5-80 units per structural unit of formula 1, especially 1-30 vinyl comonomer units per structural unit of formula 1, and particularly preferably 5-20 units per unit of formula 1 .

Furthermore, it is preferred to use a hydrophobic vinyl comonomer or a mixture of hydrophobic vinyl comonomers with hydrophobic vinyl comonomers, wherein the mixture contains at least 90% by weight of hydrophobic vinyl comonomers. In this way, the mechanical properties of polymers can be improved without significantly reducing the water content. In principle, however, it is applicable that both conventional hydrophobic vinyl comonomers and conventional hydrophilic vinyl comonomers are suitable for copolymerization with polyvinyl alcohol containing groups of Formula 1.

Suitable hydrophobic vinyl comonomers include C_rC ₁₈-alkylacrylate and -methacrylate, C3-C₁₈-alkylacrylamide and -methacrylamide, acrylonitrile, methacrylonitrile, vinyl-C, -C₁₈-alkanoate, C.₂-C₁₈-alkene, C2-C) 8-halogenalkene, styrene, C ^^ C₆-alkylstyrene, vinylalkylether, where the alkyl portion has 1-6 C2-C carbon atoms, ₀- nadfluoroalkyl acrylate and -methacrylate or partially fluorinated acrylates and methacrylates, respectively, C 1 -C 4 -adfluoroalkylethytothiocarbonylaminoethyl acrylates and -methacrylates, acryloxy and methacryloxyalkylsiloxanes, N-vinylcarbazole, C_rC₂-alkyl esters of maleic acid, fumaric acid, itaconic acid, mesonic acid etc. Preferred are, for example, C1-C4-alkyl esters of vinyl unsaturated carbonic acids with 3-5 carbon atoms or vinyl esters of carbonic acids containing up to 5 carbon atoms.

Particularly suitable hydrophobic vinyl comonomers include methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, vinyl acetate, vinyl propionate, vinyl butyrate, valerate , vinyl chloride, vinylidene chloride, acrylonitrile, 1-butene, butadiene, methacrylonitrile, vinyltoluene, vinyl ethyl ether, perfluorhexythethiothiocarbonylaminoethyl methacrylate, isobomyl methacrylate, trifluoroethyl methacrylate, hexafluoroisopropyl methacrylate, hexafluorobutyl methacrylate, tris-trimethylsilyloxysiloxyloxy-methoxyloxyloxyloxyloxyloxy

Suitable hydrophyte vinyl comonomers include, hydroxy substituted low alkyl acrylates and low alkyl methacrylates, acrylamide, methacrylamide, low alkyl acrylamides and lowalkyl methacrylamides, ethoxylated acrylates and methacrylates, hydroxy acrylaminoalkylnalkyl substituted alkyalkylnalkylnalkyalkylene ', 2-acrylamido-2-methylpropanesulfonic acid, N-vinylpyrrole, N-vinyl succinimide, N-vinylpyrrolidone, 2- or 4-vinylpyridine, acrylic acid, methacrylic acid, amino- (where the term "amino" also includes a quaternary ammonium group), monoacrylates and mono6

178 192 lowalkylamino methacrylates or dialkylaminoniumalkylmethacrylates, allyl alcohol, etc. Preferred are, for example, hydroxy acrylate-substituted acrylates and methacrylates (T-Cpkylkyl, five- to seven-membered N-alkyl lactames. NN-di-C 1 -C 6 -alkyl alkyl and alkyl acrylate) carbon atoms.

Examples of suitable hydrophyte vinyl comonomers include hyeroxnetnnone methacrylate, hyeroxyethylnone acrylate, acrylamide, methacrylamide, dimethacrylamide, allyl alcohol, vinyl pyrindine, vinyl pyrrolidinone, glyceryl methacrylate, n-oxo-1,1-oxo-1

Preferred hydrophobic vinyl knmonnmers are methyl methacrylate and vinyl acetate.

Preferred hydrophyte vinyl chamber cells are 2-hydroxyethyl methacrylate, N-vinylpyrrolidine and kernel.

The prepolymers of the invention can be processed into molded bodies in a known manner, in particular into contact lenses, for example by photocrosslinking the prepolymers of the invention in a form suitable for contact lenses. Further examples, in addition to contact lenses, include biomedical fittings or special ophthalmic fittings, e.g. intraocular lenses, ophthalmic dressings, fittings that can be used in surgery such as cardiac valves, artificial arteries, etc., in addition to films or membranes, e.g. membranes for controlling diffusion, films with an optical structure for recording information or photoresists, e.g. membranes or masks for etching or screen printing.

A special embodiment of the invention relates to contact lenses which comprise a polymer made from the prepolymer according to the invention or are essentially or completely composed of this polymer. These types of contact lenses have a whole range of extraordinary and extremely beneficial properties. These properties include, for example, excellent compatibility with the human cornea, which is based on a balanced ratio of water content, oxygen permeability and mechanical properties. In addition, contact lenses are characterized by high shape stability. Even after autoclaving, for example at about 120 ° C, no shape changes can be demonstrated.

In addition, it should be emphasized that contact lenses, in particular those comprising a polymer from a prepolymer comprising jeeonsticks according to formula 1, can be manufactured in a very simple and efficient manner compared to the prior art spnsnbomi. It consists of several factors. On one hand, starting materials can be obtained or made cheaply. Secondly, the advantage is that the prepolymers are surprisingly stable so that they can be subjected to high purification. Therefore, a material that practically no longer requires any subsequent purification, especially the costly extraction of non-polymeric components, can be used for crosslinking. Furthermore, the polymerization can take place in an aqueous solution, so that a subsequent hydration step is no longer needed. Lastly, photopnlimerosis occurs in a short time, so that the process of making contact lenses can be carried out extremely profitably also from this point of view.

Of course, all the above-mentioned advantages apply not only to contact lenses, but also to other fittings. The sum of the various aspects used in the manufacture of the moldings leads to the fact that moldings made with the prepolymer according to the invention are particularly well suited as a mass product, for example as contact lenses which are worn for a short time and then replaced with new lenses.

Contact lenses can be manufactured in a known manner, such as in the conventional "spin-castmg-mold" form, as described, for example, in US-A-3 408 429 or according to the so-called full form method in static form, as described e.g. in US-A-4,347,198.

It has been found that the method previously described on the basis of prepolymers containing the units according to formula 1 can generally be used. Moldings obtained in this way by cross-linking are insoluble in water, but swell in it.

17J8192

In particular, this method of producing shaped bodies, especially contact lenses, is characterized by having the following steps:

a) preparation of a substantially aqueous solution of water-soluble prepolymer which contains groups capable of cross-linking,

b) introducing the resulting solution into a form,

c) triggering crosslinking,

d) opening the mold so that the fitting can be removed from the mold.

Unless otherwise expressly excluded, the claims and advantages given previously in connection with the prepolymers containing the units according to formula 1, and the claims and advantages given in connection with the method of making polymers and moldings, contact lenses from such prepolymers, also apply in connection with the one described in the previous paragraph with a method comprising steps a), b), c) and d). These statements apply to all those cases in which the arguments and advantages of polymers containing the units of formula 1 may find purposeful use in the manner described in the previous paragraph.

The criteria for the Prepolymer to be used in the method described above is that the Prepolymer is water-soluble and contains cross-linkable groups.

The preparation of a substantially aqueous solution of a water-soluble prepolymer containing crosslinkable groups can take place in a known manner, for example by synthesizing the prepolymer in a substantially aqueous solution or by isolating the prepolymer, for example in pure form, i.e. without undesirable components and dissolving in a substantially aqueous medium.

By the criterion that the prepolymer is water-soluble, it is particularly meant that the prepolymer is soluble in a substantially aqueous solution at a concentration of 3-90% by weight, preferably 5-60% by weight, especially 10-60% by weight.

In the specific case, it is also possible for the prepolymer concentration to be above 90%. Particularly preferred are concentrations of prepolymer in the solution from 15 to 50% by weight, especially from 15 to 40% by weight, e.g. from 25 to 40% by weight.

In general, aqueous prepolymer solutions include, in particular, solutions of prepolymers in water and in aqueous salt solutions, especially in aqueous salt solutions that have an osmotic capacity of 200 to 450 milliosmoles in 1000 ml (unit: mOsm / 1), preferably an osmotic molarity of 250 to 350 mOsm / 1, especially 300 mOsm / 1, or in mixtures of water or aqueous saline solutions with physiologically compatible polar organic solvents such as glycerin. Pre-polymer solutions in water or in aqueous salt solutions are preferred.

Aqueous saline solutions are preferably physiologically compatible salt solutions such as buffer salts, e.g. phosphate salts normally used in contact lens care, or toning agents normally used in contact lens care, in particular alkali halides, e.g. sodium chloride, or also solutions of their mixtures. An example of a particularly suitable salt solution is an artificial, preferably buffered, tear liquid which, in terms of pH and osmotic molarity, is matched to the natural tear liquid, e.g. phosphate buffered saline, whose osmotic molarity and pH value correspond to the osmotic molarity and pH value of the human liquid tear.

The essentially aqueous prepolymer solutions defined above are preferably pure solutions, i.e. those which are free from or substantially free from undesirable components. Pre-polymer solutions in pure water or in the artificial tear fluid described above are particularly preferred.

The viscosity of the prepolymer solution in the substantially aqueous solution is broadly uncritical. However, it should preferably be liquid solutions that are suitable for stress-free shaping.

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The molecular weight of the prepolymer is also non-critical within wide limits. Preferably, however, the prepolymer has a molecular weight of 10,000 to 200,000.

The prepolymer of the invention must further contain crosslinkable groups. Cross-linkable groups are understood to be normal, cross-linkable groups known to the skilled artisan, such as, for example, cross-crosslinkable or thermally cross-linkable groups. Particularly suitable for such cross-linkable groups have already been proposed in the production of contact lens materials. These are especially, but not exclusively, groups containing carbon-carbon double bonds. To demonstrate the versatility of cross-linkable groups at stake here, only cross-linking polymerization, 2 + 2 cycloaddition, Diels-Adler reactions, ROMP (Ring Opening Metathesis Polymerisation), vulcanization, cationic crosslinking or epoxy curing should be mentioned as cross-linking mechanisms.

As water-soluble prepolymers that contain crosslinkable groups, compounds containing the units of formula 1 are suitable. In addition, other water-soluble prepolymers which contain a polymeric backbone and crosslinkable groups can also be used in the process.

In addition to polyvinyl alcohol, polymeric backbones include materials such as those already proposed as contact lens materials, e.g. polymeric diols differing from PVA, saccharide-containing polymers, polymers containing vinylpyrrolidone, polymers containing alkyl (meth) acrylate, which are substituted with groups hydrophyte, such as a hydroxy, carboxy or amino group, alkene polyglycols or copolymers, or mixtures thereof.

The prepolymer according to the invention contains crosslinkable groups preferably in an amount of 0.5 to 80% equivalents with respect to the monomer equivalents that form the polymer base skeleton, especially from 1 to 50%, more preferably from 1 to 25%, more preferably from 2 to 15%, particularly preferably from 3 to 10%. Particularly preferred are the contents of groups capable of crosslinking from 0.5 to 25% equivalents, especially from 1 to 15%, and particularly preferably from 2 to 12% with respect to the monomer equivalents that form the polymer base skeleton.

As already mentioned, it is important for the usefulness of the prepolymer that it be cross-linkable. However, this prepolymer is uncrosslinked or at least substantially crosslinked such that it is water soluble. Furthermore, the prepolymer is preferably stable in a non-crosslinked state, such that it can be subjected to purification, as described above for compounds containing units according to formula 1. Prepolymers are preferably used in the form of pure solutions. The prepolymer can be converted into pure solutions, for example as described below.

Preferably, the Prepolymer can be purified in a known manner, for example by precipitation with an organic solvent such as acetone, by filtration and washing, by extraction in a suitable solvent, by dialysis or ultrafiltration, ultrafiltration being particularly preferred. Thanks to this cleaning operation, prepolymers can be obtained in extremely pure form, e.g. as concentrated aqueous solutions which are free or at least substantially free of reaction products such as salts and starting materials such as, for example, non-polymerized components.

The preferred method of purifying the prepolymers of the invention, ultrafiltration, can be carried out in a known manner. There is also the possibility of repeated ultrafiltration, for example two to ten times. Alternatively, ultrafiltration can also be carried out continuously until the desired degree of purity is reached. The desired degree of purity can generally be chosen as high as you like. A suitable measure of the degree of purity is, for example, the content of table salt in a solution that can be easily determined in a known manner.

Preferably, in step a) of the process, a substantially aqueous prepolymer solution is prepared and further used, the solution being substantially free of undesirable

178 192 components, for example, are free of monomeric, oligomeric or polymeric starting materials that have been used to prepare the prepolymer and / or by-products that have been formed in the preparation of the prepolymer. This essentially aqueous solution is particularly preferably a pure aqueous solution or a solution in the artificial tear liquid described above. In addition, it is preferred to carry out this method without the addition of comonomers, for example vinyl comonomers.

Due to the measures mentioned in the previous paragraph, and in particular due to their combination, the prepolymer solution according to the invention used in the process does not contain any or substantially no undesirable components; which would have to be extracted after cross-linking. It is therefore particularly advantageous that extraction of undesirable components after the crosslinking can be dispensed with.

The process is therefore preferably carried out such that a substantially aqueous solution of water-soluble prepolymer is used which contains crosslinkable groups and is free or essentially free of undesirable components (such as in particular monomeric, oligomeric or polymeric starting materials which have been used to prepare prepolymer or by-products that have arisen in the production of the prepolymer) and that this solution is used without the addition of a comonomer, that in the further course of this process it is possible to dispense with the extraction of any undesirable components.

An additive, which is optionally added to the prepolymer solution, is a crosslinking initiator if an initiator is needed to crosslink the groups capable of crosslinking. This can be the case especially when crosslinking occurs via photocrosslinking, which is advantageous in this method.

In the photo-crosslinking, a photoinitiator is added that can initiate radical crosslinking. Such examples are known to those skilled in the art; especially suitable photoinitiators include benzinomethyl ether, 1-hydroxycyclohexylphenyl ketone or industrial products such as various types of Darocure or Irgacure materials, e.g. Darocure 1173 [2-hydroxyprop-2-yl-phenone] or Irgacure 2959 [4 '(P-hydroxyethoxy) -2-hydroxyprop-2-yl-phenone].

Known methods can be used to introduce the resulting solution into the mold, in particular conventional dosing, e.g. by dropping. Contact lenses made using the prepolymer according to the invention can be produced in a known manner, as mentioned above, e.g. in a conventional spin-casting mold, as for example described in US-A-3 408 429 or according to the so-called full mold method in static in a form as described, for example, in US-A-4,347,198. Suitable forms are, for example, made of polypropylene. Suitable mold materials for reuse are, for example, quartz, sapphire glass or metals.

Cross-linking can be triggered in a form e.g. by actinic radiation, e.g. ultraviolet radiation or ionizing radiation, e.g. gamma radiation, electron radiation or X-rays. Optionally, crosslinking can also be triggered thermally. It should be emphasized here that crosslinking can take place in a very short time, for example in less than 5 minutes, preferably in less than 1 minute, especially in up to 30s, and in particular at such time as described in the examples.

Opening the mold to remove the mold can take place in a known manner. However, in prior art methods it is necessary to include purification steps, e.g. by extraction and a hydration step of the obtained body, especially contact lenses, while such steps are not needed in the process using the prepolymer according to the invention.

Because the prepolymer solution preferably does not contain any undesirable low-molecular-weight components, the cross-linked product also does not contain such components. Thanks to this, there is no need for subsequent extraction. Since crosslinking is carried out in a substantially aqueous solution, there is no subsequent hydration. Both of these advantages, among other things, lead to the elimination of costly finishing of the obtained molded parts, especially contact lenses. Contact lenses obtained by the process using the prepolymer according to the invention are therefore preferably characterized in that they can be used without extraction for their intended purpose. Proper use is understood to mean that contact lenses can be placed in the eyes of people. The contact lenses obtained by the process using the prepolymer according to the invention are further advantageously characterized by the fact that they are suitable for their intended use without hydration.

This method has therefore proved to be extremely well adapted to the rational production of a large number of shaped bodies, such as contact lenses, in a short time. Contact lenses obtained by the method using the prepolymer according to the invention have, in relation to contact lenses known in the art, among others the advantage that they can be used as intended immediately after manufacture, i.e. bypassing additional treatment (such as extraction or hydration) .

In the examples below, the quantitative data, unless expressly stated otherwise, are by weight and the temperature values ​​are given in degrees Celsius. The abbreviation "Mn" means number average molecular weight and the abbreviation "Mw" means weight average molecular weight.

Example la. To 105.14 parts of aminoacetaldehyde-dimethylacetal and 101.2 parts of triethylamine in 200 parts of dichloromethane, 104.5 parts of methacryloyl chloride dissolved in 105 parts of dichloromethane at a maximum temperature of 15 ° C for 4 hours are added dropwise after ice-cooling. After completion of the reaction, the dichloromethane phase was washed with 200 parts of water, followed by 200 parts of 1-normal HCl solution, and then twice with 200 parts of water. After drying over anhydrous magnesium sulfate, the dichloromethane phase was evaporated and stabilized with 0.1%, based on the reaction product, 2-6-di-tert.-butyl-p-cresol. After distillation at 90 ° C / 0.1 Pa, 112 g was obtained, 112 g of methacrylamidoacetaldehyde-dimethylacetal was obtained as a colorless liquid with a boiling point of 92 ° C / 0.1 Pa (65% yield).

Example 1b. 52.6 g of aminoacetaldehyde-dimethylacetal were dissolved in 150 ml of deionized water and cooled with ice to 5 ° C. Then 50 ml methacrylic acid chloride and 50 ml 30% sodium hydroxide were added simultaneously for 40 minutes so that the pH remained at 10 and the temperature did not rise above 20 ° C. After the addition, the remaining content of aminoacetaldehyde-dimethylacetal was determined by gas chromatography to be 0.18%. Amine was completely processed by further addition of 2.2 mL methacrylic acid chloride and 2.0 mL 30% sodium hydroxide. The solution was then neutralized with 1-normal hydrochloric acid (pH = 7). The aqueous phase was extracted with 50 ml of petroleum ether and rinsed with water. The petroleum ether phase contained 3.4 g of by-product. The aqueous phase was purified to give 402.8 g of a 20.6% methacrylamidoacetaldehyde-dimethylacetal solution. This product is, according to the gas chromatogram, 98.2%.

Example 2. 10 parts of polyvinyl alcohol with a molecular weight of 22,000 and a degree of saponification of 97.5-99.5% were dissolved in 90 parts of water, mixed with 2.5 parts of methacrylamidoacetaldehyde-dimethylacetal and acidified with 10 parts of concentrated hydrochloric acid. This solution was stabilized with 0.02 parts of 2,6-di-tert.-butyl-p-cresol. After stirring for 20 hours at room temperature, this solution was adjusted with 10% sodium hydroxide to pH 7, followed by ultrafiltration through a 3KD membrane seven times (1: 3 ratio).

After concentration, 18.8% aqueous solution of polyvinyl alcohol methacrylamidoacetaldehyde-1-3acetal was obtained with a viscosity of 2240 mPas at 25 ° C.

Example 3. 10 parts of the polyvinyl alcohol-methacrylamidoacetaldehyde-1,3-acetal solution obtained in Example 2 were crosslinked photochemically by adding 0.034 parts of Darocure 1173 (CIBA-GEIGY). This mixture as a 100 mm thick layer between glass plates was irradiated with 200 pulses of 5000 W Staub irradiation apparatus. A rigid, transparent film with a solids content of 31% was obtained.

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Example 4. 110g polyvinyl alcohol (Moviol 4-88, Hoechst) was dissolved in 440 g deionized water at 90 ° C and cooled to 22 ° C. To this solution, 100.15 g of a 20.6% aqueous solution of methacrylamidoacetaldehyde-dimethylacetal, 38.5 g of concentrated hydrochloric acid (37%, Merck) and 44.7 g of deionized water were added. This mixture was stirred for 22 h at room temperature and then adjusted to pH = 7.0 with a 5% NaOH solution. This solution was diluted with deionized water to 3 L, filtered and ultrafiltered through a Filtron 1-KD-Omega-Membran membrane. After passing the sample volume three times, the solution was concentrated. 660 g of a 17.9% solution of polyvinyl alcohol-methacrylamidoacetaldehyde-1,3-acetal with a viscosity of 210 mPa.s The inherent viscosity of the polymer was 0.319. The nitrogen content was 0.96%. According to NMR, 11 mol% OH groups were acetalized, and 5 mol% OH groups were acetylated. By concentrating the aqueous polymer solution under reduced pressure and with air flow, a 30.8% solution with a viscosity of 3699 mPa · s was obtained.

Example 5. To 133.3 g of a 15% polyvinyl alcohol solution (Moviol 4-88, Hoechst) was added 66.6 g of deionized water, 3.3 g of monomeric 4-methacrylamidobutyraldehyde-diethylacetal and 20.0 g of concentrated hydrochloric acid (37% , Merck) and stirred for 8 hours at room temperature. Then with 5% sodium hydroxide this solution was adjusted to pH = 7. After ultrafiltration of this solution through a 3KD-Omega-Membran membrane from Filtron (the sodium chloride content of the polymer solution decreases from 2.07% to 0.04%), a 20% polymer solution of polyallcohol-methacrylamidobutyra-lalllehydo-1,3-acetal vinyl with a viscosity of 400 mPa p. Logarithmic viscosity number of this limer was 0.332. The nitrogen content was 0.41%. According to NMR, 7.5 mole% OH groups were saturated with acetyl groups, and 7.3 mole% OH groups were saturated with acetate groups.

Example 6. 2.4 g (14.8 mmol) of aminobutyraldehyde-diethylacetal (Fluka) and 20 g of concentrated hydrochloric acid (3.7%, Merck) were added to 200 g of a 10% solution of polyvinyl alcohol (Moviol 4-88, Hoechst). . This solution was stirred for 48 hours at room temperature and then neutralized with 10% sodium hydroxide. The solution was diluted to 400 ml. 200 ml of this solution was further processed according to example 7. To the remaining 200 ml of this solution, 0.85 g (8.1mmol) of methacrylic acid chloride (Fluka) was added, and the pH was maintained at pH = 10 with 2-normal sodium hydroxide. After 30 minutes at room temperature the value was set pH = 7.0 and the solution was purified through a Filtron 3-KD-Omega-Membran membrane in an analogous manner as in Example 5. After concentration, a 27.6% polymer solution of polyvinyl alcohol methacrylamidobutyraldehyde-1,3-acetal with a viscosity of 2920 mPa.s was obtained. The logarithmic viscosity of this polymer was 0.435. The nitrogen content was 0.59%.

Example 7. 1.3 g (8.5 mmol) of 2-isocyanatoethyl methacrylate methacrylate was added to 200 ml of the polymer solution of Example 6, and pH = 10 was adjusted with 2-normal sodium hydroxide. After 15 minutes at room temperature, the solution was neutralized with 2- normal hydrochloric acid and ultrafiltered in an analogous manner to Example 6. After concentration, a 27.1% polymer solution of 4- (2-methacrylate? -ylethyl-urcH) is obtained, bi-utty-yd (^ k ^ lh ^ yd ^^ 1) , 3-acetal polyvinyl alcohol with a viscosity of 2320 mPa · s. The inherent viscosity of the polymer was 0.390. The nitrogen content was 1.9%.

Example 8. Up to 30.8% polymer solution according to example 4 with a viscosity of about 3600 mPa. s 0.7% Darocur 1173 (based on polymer content) was added. This solution was filled into a transparent contact lens mold made of polypropylene and the mold closed. This solution was irradiated with an Oriel 200 W ultraviolet lamp for 6 s at a distance of 18 cm. The mold was opened and the finished contact lens was removed. The lens was transparent and had a water content of 61%. The module was 0.9 mPa and the elongation at break was 50%. The contact lens was autoclaved at 121 ° C for 40 min. There was no change in the shape of the lens after this treatment.

Example 9. To 10.00 g 27.1% polymer solution according to example 7 0.0268 g Darocur 1173 (0.7% based on polymer content) and 0.922 g methyl methacrylate were added. After the addition of 2.6 g methanol a clear solution was obtained. This solution, as in example 8, was irradiated with a 200 W Oriel lamp for 14 seconds. A transparent contact lens with a water content of 70.4% was obtained.

Example 10. To 12.82 g of a 24.16% prepolymer solution from Example 4 1.04 g of acrylamide and 0.03 g of Darocur 1173 were added. The transparent solution was then irradiated, similarly to example 8, for 14 seconds with an Oriel 200 lamp W. A contact lens with a water content of 6.44% was obtained.

Example 11. 220 g (5.5 mol) of sodium hydroxide in 300 g of water and 700 g of ice are dissolved in a stirred and reactor with cooling and cooling. Sodium hydroxide is cooled to 10 ° C. 526 g (5.0 mol) of aminoacetaldehyde-dimethylacetal and 50 mg of 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (radical inhibitor) are added. To this solution, 548.6 g (5.5 mol) of methacrylic acid chloride is slowly added over 3.5 hours at 10 ° C. After the addition, the pH decreases slowly to 7.2; by gas chromatography the presence of amine can no longer be detected. The reaction mixture is extracted with 500 ml of petroleum ether to remove impurities, the aqueous phase is saturated with table salt and extracted three times with 500 ml of tertiary ether-methyl ether. The organic phase is dried with magnesium sulfate, filtered and concentrated on a rotary evaporator. The obtained 882.2 g of yellowish oil are added, under stirring with an Ultraturax apparatus, to 2000 ml of petroleum ether at -10 ° C. The product crystallizes, is filtered off and dried. 713.8 g of methacrylamidoacetaldehyde-dimethylacetal are obtained (86% of theory). Melting point 30-32 ° C; according to gas chromatography the product is 99.7%.

Example 12. 40 g (1.0 mol) of sodium hydroxide in 100 g of water and 200 g of ice are dissolved in a stirred and reactor 11 reactor. Sodium hydroxide is cooled to 10 ° C. 105.1 g (1.0 mole) of aminoacetaldehyde-dimethylacetal and 10 mg of 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl inhibitor are added. To this solution, 99.5 g (1.1 mol) of acrylic acid chloride is slowly added over 2 h at 10 ° C. The pH decreases slowly and finally settles to pH = 7. According to gas chromatography, no amine was found. The reaction mixture is saturated with table salt and extracted three times with 200 ml of tertiary butyl methyl ether. The organic phase is dried, filtered and concentrated in a rotary evaporator. The oil obtained is extracted three times with petroleum ether and then dried again by rotary evaporation. 130 g of acrylamidoacetaldehyde-dimethylacetal are obtained (81% of theory) as an oil. According to gas chromatography, the product is 99%.

Example 13. General production method for the reaction of PVA with acetals or aldehydes to produce exchange products with a high acetate content.

300 g of PVA (e.g. Moviol Hoechst 4-88) are placed in a double jacketed reactor with a stirrer and a thermometer, 800 g of deionized water are added and heated to 95 ° C with stirring. After an hour, everything is clearly dissolved and the solution is cooled to 20 ° C. 27 g (0.155 mol) of methacrylamidoacetaldehyde-dimethylacetal (from Example 11), 44 g of acetic acid, 100 g of concentrated hydrochloric acid (37%) and so much deionized water are added that together 2000 g of reaction solution are obtained (in the specific case: 333 g). This mixture is stirred for 20 h at 20 ° C. The change in acetate content can be determined by acetic acid titration.

Isolation can be carried out by ultrafiltration. The reaction mixture is cooled to 15 ° C and adjusted with aqueous NaOH (5%) at pH 3.6. The polymer solution is filtered through a 0.45 mm filter and purified by ultrafiltration. Ultrafiltration is carried out using a 1KD Omega Membran membrane from Filtron. Ultrafiltration is carried out until a residual kitchen salt content of 0.004% is obtained. Before the purification is completed, the solution is adjusted with 0.1 N sodium hydroxide to pH = 7. After concentration, 1995 g of a 14.45% polymer solution (92% of theory) are obtained. N content (reference

178 192 ^^ - οΗο) = 0.683%, acetate content (determined by hydrolysis) = 2.34 milliroviector / g, logarithmic viscosity number: 0.310, cross-linking: 0.5 millirovorotoric / g determined by micro-development), free hydroxy groups (determined by reacetylation): 15.3 milliequire weight / g, GPC analysis (in water): Mw = 19102, Mn = 7522, Mw / Mn = 2.54.

Isolation can also be carried out by precipitation. The reaction mixture is adjusted to triethylamine at pH 3.6 and precipitated with acetone in a ratio of 1:10. The precipitate is separated, dispersed twice with ethanol and once with acetone, and dried. The product obtained has the same properties as the product obtained by ultrafiltration.

Example 14. General production method for the PVA reaction with acetolomi or aleehyodes to produce low-acetate exchange reaction products.

300 g of PVA (e.g. Moyfol Hoechst 4-88) were placed in a double jacketed reactor with stirrer and thermometer and 800 g of deionised water was added, followed by heating to 95 ° C with stirring. After one hour, everything dissolved well and the solution was cooled to 20 ° C. Dneaoo 27 g (0.155 mol) of methacryloomidoacetaldehyde dimethylene from Example 11), 200 g of concentrated hydrochloric acid (37%) or as much de-ionized wney that together 2000 g of reaction solution (673 g in the present case) were obtained. This mixture was stirred at 20 ° C. After 20 h, a sample of the reaction solution was titrated with NaOH and the degree of PVA hydrolysis was determined: HCl = 1.034 milliequivalent / g, acetic acid = 0.265 milliequivalent / g, 3.5 mol% equivalent. residual acetates. The reaction mixture was stirred for a further 2 h at 25 ° C and again titrated: HCl = 1.034 milliequivalent / g, acetic acid = 0.277 milliethweight / g respectively 2.93 mol%. residual acetates.

Isolation can be carried out after filtration. The reaction mixture is cooled to 15 ° C and the pH is adjusted to 7 with aqueous NaOH (5%). The polymer solution is filtered through a 0.45 mm filter and purified by ultrafiltration. Ultrafiltration is carried out using a 1 KD Omega Membran membrane from Filtron. It is filtered until the residual kitchen salt content is 0.002%. The result is 1800 g of 14.02% polymer solution (86% of theory); N content (determination according to Kjendohl) = 0.741%, acetate content (after titration) = 0.605 milliequivalents / g, 2.91 mol%, respectively, logarithmic viscosity number 0.327, double bond: 0.61 millirovariant / g (determination by mlwouwndomlenle) free hydroxy groups (determined by reacetylation) 18.13 milliequivalents / g, GPC analysis (in water) Mw = 22007, Mo = 9743, Mw / Mn = 2.26.

Isolation can also be performed by precipitation. The reaction mixture is adjusted to pH 3.6 with triethnnomine and precipitated with acetone in a ratio of 1:10. The precipitate is separated twice, dispersed with ethanol and once with acetone, and dried. The product thus obtained is comparable to the product obtained by ultrafiltration.

Example 15. Preparation of contact lenses. The 30% solution of the polymers listed below is crosslinked with 0.3% (based on the polymer content) of the Irgacure 2959 photomiator. In a transparent form for contact lenses made of polypropylene, the solutions are irradiated with an Oriel 200 W ultraviolet lamp (150 mW / cm²) for 6 s. Lenses are removed from the mold. They are transparent and have the following properties.

Examples 15a) to 15j). PVA processing products (4-88) Movtol Hoechst, 12 mol% residual acetates, Mw = 19,115, Mn = 7,887, Mw / Mn = 2.43 log viscosity number 0.358, according to the production method of Example 13 or 14, isolation by ultrafiltration.

15a). 30 g acetal from example 11, production method according to example 13, addition of acetic acid: 700 g, inherent viscosity: 0.278, prepolymer (sol) data: content 1.34% acetal content: 0.96 milliequivalent / g, acetate content 19 mole%

Mw: 17412, Mn: 6273, Mw / Mn: 2.77 30% in the sol scale and up to 38.4% in the gel content of solids:

178 192

15b). 24 g acetal from Example 11, production method according to Example 13, addition of acetic acid: 300 g, inherent viscosity: 0.329 prepolymer data (sol): Ni content 0.64% acetal content: 0.45 milliequivalent / g, acetate content: 9 mole%

solids content: 30% in the solvate state up to 29.5% in the gel state

15c). 24 g acetal from Example 11, production method according to Example 13, addition of acetic acid: 700 g, inherent viscosity: 0.331, prepolymer data (sol): N content: 0.58% acetal content: 0.42 milliequivalents / g, content acetate: 17.5 mol%

Mw: 18861, Mn: 8051, Mw / Mn: 2.34 solids content: 30% in the sol state leads to 27.6% in the gel state

15d) 30 g acetal from Example 11, production method according to Example 13, addition of acetic acid: 500 g, inherent viscosity: 0.327, prepolymer (sol) data: N content and 0.753% acetal content: 0.54 milliequivalents / g, acetate content : 12.5 mol%

Mw: 19463, Mn: 8064, Mw / Mn: 2.41 solids content: 30% in the sol stagnates up to 30.0% in the gel state

15e). 56 g of the acetal from Example 11, production method of Example 13, addition of acetic acid: 1000 g, prepolymer (sol) data: N content and 1.208% acetal content: 0.86 mEq / g, acetate content: 26 mol%.

Mw: 17412, Mn: 6273, Mw / Mn: 2.77 solids content: ^ 0% in sOniie zohi leads to 36.7% in the gel state

15f). 24 g acetal from Example 11, production method according to Example 14, no acetic acid added, inherent viscosity: 0.321, prepolymer (sol) data: Ni content 0.659% acetal content: 0.46 mEq / g, acetate content: 5.9 mol%

Mw: 27121, Mn: 6490, Mw / Mn: 4.18 solids content: 30% in the sol state leads to 30.0% in the gel state.

15g). 48 g of the acetal from Example 11, production method of the example, no addition of acetic acid, logarithmic prepolymer (sol) data: N content and 1.23% acetal content: 0.88 milliequivalents / g, acetate content: 6.6 mol%.

Mw: 18833, Mn: 7047, Mw / Mn: 2.66 solids content: 30% in the sol state leads to 36.7% in the rye state

15h). 27 g acetal from Example 11, production method according to Example 14, no acetic acid added, inherent viscosity: 0.31, prepolymer (sol) data: N content: 0.638% acetal content: 0.53 milliequivalents / g, acetate content 2.9 mole%

Mw: 19101, Mn: 7522, Mw / Mn: 2.54 solids content: 30% in the sol state leads to 30.0% in the rye state.

15i). 31 g acetal from Example 12, production method according to Example 14, no acetic acid added,

178 192 prepolymer data (sol): N content: 1.41% acetal content: 1.00 milliequivalent / g, acetate content: 6.2 mol%

solids content: 30% in the sol state leads to 37.0% in the gel state.

15j). 23 g acetal from example 12, production method according to example 14, no acetic acid added, inherent viscosity: 0.352, prepolymer data (sol): N content: 0.62% acetal content: 0.44 milliequivalents / g, acetate content 5.8 mole%

Examples 15k) -151). PVA processing products (8-88) Moviol Hoechst, 12 mol% residual acetate, Mw - 49000, Mn = 19600, Mw / Mn = 2.5, inherent viscosity = 0.546, according to the production method of Example 13, isolation by ultrafiltration.

k). 53 g of the acetal from Example 11, addition of acetic acid: 400 g, prepolymer data (sol): N content: 1.31% acetal content: 0.94 milliequivalents / g, acetate content: 8.9%.

151). 30 g of the acetal from Example 11, addition of acetic acid: 490 g, inherent viscosity: 0.495 prepolymer data (sol): N content: 0.747% acetal content: 0.54 milliequivalents / g, acetate content: 13.6 mol%, content Solids: 30% in the sol state leads to 30.5% in the gel state.

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