Ocular lens material

Abstract: An ocular lens material made of a copolymer consisting essentially of (A) a polysiloxane macromonomer having polymerizable groups bonded via one or more urethane bonds to the siloxane main chain, of the formula (I): A¹-U¹-(-S¹-U²-) n -S²-U³-A² (I) wherein A¹ is a group of the formula (II): Y²¹-R³¹- (II) wherein Y²¹ is an acryloyloxy group, a methacryloyloxy group, a vinyl group or an allyl group, and R³¹ is a linear or branched alkylene group having from 2 to 6 carbon atoms; A² is a group of the formula (III): -R³⁴-Y²² (III) wherein Y²² is an acryloyloxy group, a methacryloyloxy group, a vinyl group or an allyl group, and R³⁴ is a linear or branched alkylene group having from 2 to 6 carbon atoms; U¹ is a group of the formula (IV): -X²¹-E²¹-X²⁵-R³²- (IV) wherein X²¹ is a covalent bond, an oxygen atom or an alkylene glycol group having from 1 to 6 carbon atoms, E²¹ is -CONH- (provided that in this case, X²¹ is a covalent bond, and E²¹ forms an urethane bond together with X²⁵) or a bivalent group derived from a diisocyanate selected from the group consisting of saturated aliphatic, alicyclic and aromatic diisocyanates (provided that in this case, X²¹ is an oxygen atom or an alkylene glycol group having from 1 to 6 carbon atoms, and E²¹ forms an urethane bond together with X²¹ and X²⁵), X²⁵ is an oxygen atom or an alkylene glycol group having from 1 to 6 carbon atoms, and R³² is a linear or branched alkylene group having from 1 to 6 carbon atoms; Each of S¹ and S² independently represents a group of the formula (V): wherein each of R²³, R²⁴, R²⁵, R²⁶, R²⁷ and R²⁸ independently represents an alkyl group having from 1 to 3 carbon atoms or a phenyl group, K is an integer of from 1 to 50, and L is an integer of from 0 to (50-K); U² is a group of the formula (VI): -R³⁷-X²⁷-E²⁴-X²⁸-R³⁸- (VI) wherein each of R³⁷ and R³⁸ independently represents a linear or branched alkylene group having from 1 to 6 carbon atoms, each of X²⁷ and X²⁸ independently represents an oxygen atom or an alkylene glycol group having from 1 to 6 carbon atoms, and E²⁴ is a bivalent group derived from a diisocyanate selected from the group consisting of saturated aliphatic, alicyclic and aromatic diisocyanates (provided that in this case, E²⁴ forms an urethane bond together with X²⁷ and X²⁸); U³ is a group of the formula (VII): -R³³-X²⁶-E²²-X²²- (VII) wherein R³³ is a linear or branched alkylene group having from 1 to 6 carbon atoms, X²² is a covalent bond, an oxygen atom or an alkylene glycol group having from 1 to 6 carbon atoms, X²⁶ is an oxygen atom or an alkylene glycol group having from 1 to 6 carbon atoms, and E²² is -CONH- (provided that in this case, X²² is a covalent bond, and E²² forms an urethane bond together with X²⁶) or a bivalent group derived from a diisocyanate selected from the group consisting of saturated aliphatic, alicyclic and aromatic diisocyanates (provided that in this case, X²² is an oxygen atom or an alkylene glycol group having from 1 to 6 carbon atoms, and E²² forms an urethane bond together with X²² and X²⁶); and n is an integer of at least 1; and (B) an alkyl (meth)acrylamide, wherein the weight ratio of the polysiloxane macromonomer to the alkyl (meth)acrylamide is from 10:90 to 90:10.

Description: The present invention relates to an ocular lens material. More particularly, it relates to an ocular lens material which has high oxygen permeability and high strength and which is useful for e.g. contact lenses, intraocular lenses or artificial cornea. Heretofore, it has been known that a soft material is usually preferred as a material for contact lenses giving comfortable feeling to wearers, or as a material for intraocular lenses which can be inserted in a modified shape through a small incision of the eye ball without damaging eye tissues. Such a soft material includes a water-absorptive material which swells and softens upon absorption of water, and a substantially non-water absorptive material. With such a water-absorptive material, the oxygen permeability depends on the water absorptivity, and its oxygen permeability coefficient could never be larger than the oxygen permeability coefficient of water. In recent years, as a material for obtaining contact lenses which are water-absorptive and excellent in oxygen permeability, a material made of a copolymer of a fluorine-type (meth)acrylate monomer with a hydrophilic monomer such as 2-hydroxyethyl methacrylate, glycerol methacrylate or N,N-dimethylacrylamide, or a material made of a copolymer of such a hydrophilic monomer with a silicon-type (meth)acrylate monomer, has been proposed (Japanese Unexamined Patent Publications No. 179422/1991, No. 196117/1991 and No. 196118/1991). However, if the amount of the fluorine-type (meth)acrylate monomer or the silicon-type (meth)acrylate monomer is increased in an attempt to further improve the oxygen permeability of the material made of such a copolymer of the fluorine-type (meth)acrylate monomer with the hydrophilic monomer or a copolymer of the silicon-type (meth)acrylate monomer with the hydrophilic monomer, the resulting material will be semihard. Accordingly, it will be difficult to obtain contact lenses giving comfortable feeling to wearers or intraocular lenses which can be readily inserted in a deformed shape through a small incision of the eye ball, by using such a material. EP-A-0 109 355, EP-A-0 176 481, EP-A-0 291 452, and EP-A-0 494 842 all disclose an ocular lens material made of a copolymer as described in the preamble of claim 1. In view of the above-mentioned prior art, the present inventors have conducted extensive studies to obtain an ocular lens material which has characteristics such that 1 ○ it is excellent in transparency, 2 ○ it is excellent also in oxygen permeability, 3 ○ it has practically adequate mechanical strength, 4 ○ it has a relatively good rubber elasticity and is excellent in the dimensional stability, 5 ○ it has a practical water-absorptivity (the water content is at least 5%) and is soft in a water-containing state, 6 ○ its surface has little tackiness, 7 ○ a stain of e.g. lipid scarcely adheres, and 8 ○ it can easily be processed by cutting and grinding. As a result, it has been found that a copolymer comprising a certain specific polysiloxane macromonomer and an alkyl (meth)acrylamide as main copolymer components, is provided with such characteristics. The present invention has been accomplished on the basis of this discovery. Thus, the present invention provides an ocular lens material made of a copolymer consisting essentially of (A) a polysiloxane macromonomer having polymerizable groups bonded via one or more urethane bonds to the siloxane main chain, of the formula (I): A 1 -U 1 -(-S 1 -U 2 -) n -S 2 -U 3 -A 2 wherein A 1 is a group of the formula (II): Y 21 -R 31 - wherein Y 21 is an acryloyloxy group, a methacryloyloxy group, a vinyl group or an allyl group, and R 31 is a linear or branched alkylene group having from 2 to 6 carbon atoms; A 2 is a group of the formula (III): -R 34 -Y 22 wherein Y 22 is an acryloyloxy group, a methacryloyloxy group, a vinyl group or an allyl group, and R 34 is a linear or branched alkylene group having from 2 to 6 carbon atoms; U 1 is a group of the formula (IV): -X 21 -E 21 -X 25 -R 32 - wherein X 21 is a covalent bond, an oxygen atom or an alkylene glycol group having from 1 to 6 carbon atoms, E 21 is -CONH-, provided that in this case X 21 is a covalent bond and E 21 forms an urethane bond together with X 25 , or a bivalent group derived from a diisocyanate selected from the group consisting of saturated aliphatic, alicyclic and aromatic diisocyanates, provided that in this case X 21 is an oxygen atom or an alkylene glycol group having from 1 to 6 carbon atoms and E 21 forms an urethane bond together with X 21 and X 25 , X 25 is an oxygen atom or an alkylene glycol group having from 1 to 6 carbon atoms, and R 32 is a linear or branched alkylene group having from 1 to 6 carbon atoms; each of S 1 and S 2 independently represents a group of the formula (V): wherein each of R 23 , R 24 , R 25 , R 26 , R 27 and R 28 independently represents an alkyl group having from 1 to 3 carbon atoms or a phenyl group, K is an integer of from 1 to 50, and L is an integer of from 0 to (50-K); U 2 is a group of the formula (VI): -R 37 -X 27 -E 24 -X 28 -R 38 - wherein each of R 37 and R 38 independently represents a linear or branched alkylene group having from 1 to 6 carbon atoms, each of X 27 and X 28 independently represents an oxygen atom or an alkylene glycol group having from 1 to 6 carbon atoms, and E 24 is a bivalent group derived from a diisocyanate selected from the group consisting of saturated aliphatic, alicyclic and aromatic diisocyanates, provided that in this case E 24 forms an urethane bond together with X 27 and X 28 ; U 3 is a group of the formula (VII): -R 33 -X 26 -E 22 -X 22 - wherein R 33 is a linear or branched alkylene group having from 1 to 6 carbon atoms, X 22 is a covalent bond, an oxygen atom or an alkylene glycol group having from 1 to 6 carbon atoms, X 26 is an oxygen atom or an alkylene glycol group having from 1 to 6 carbon atoms, and E 22 is -CONH-, provided that in this case X 22 is a covalent bond and E 22 forms an urethane bond together with X 26 , or a bivalent group derived-from a diisocyanate selected from the group consisting of saturated aliphatic, alicyclic and aromatic diisocyanates, provided that in this case X 22 is an oxygen atom or an alkylene glycol group having from 1 to 6 carbon atoms and E 22 forms an urethane bond together with X 22 and X 26 ; and n is an integer of at least 1; and (B) a vinyl comonomer, wherein the weight ratio of the polysiloxane macromonomer to the vinyl comonomer is from 10:90 to 90:10, and wherein the vinyl comonomer is an alkyl (meth)acrylamide. Now, the present invention will be described in detail with reference to the preferred embodiments. As described above, the ocular lens material of the present invention is made of a copolymer comprising (A) a polysiloxane macromonomer of the formula (I) and (B) an alkyl (meth)acrylamide, as main components, wherein the weight ratio of the polysiloxane macromonomer to the alkyl (meth)acrylamide is from 10:90 to 90:10. The above polysiloxane macromonomer has elastic bonds called urethane bonds and is a component which imparts a nature to improve the mechanical strength by reinforcing the material by the siloxane moieties of this monomer without impairing the flexibility and oxygen permeability of the material and by imparting elastic resiliency to eliminate brittleness. Further, the above polysiloxane macromonomer imparts high oxygen permeability, since it has silicone chains in its molecular chain. The above polysiloxane macromonomer has polymerizable groups at both terminals of the molecule and is capable of being copolymerized with other copolymer components by such polymerizable groups. Thus, it has an excellent characteristic such that it imparts a reinforcing effect by chemical bonds (covalent bonds) in addition to the physical reinforcing effect by entanglement of molecules, to the resulting ocular lens. The above polysiloxane macromonomer is a compound of the formula (I). As mentioned above, in the formula (I), A 1 is a group of the formula (II): Y 21 -R 31 - wherein Y 21 and R 31 are as defined above, and A 2 is a group of the formula (III): -R 34 -Y 22 wherein Y 22 and R 34 are as defined above. Each of Y 21 and Y 22 is a polymerizable group and is preferably an acryloyloxy group, a methacryloyloxy group or a vinyl group in that it is readily copolymerizable with an alkyl (meth)acrylamide. Each of R 31 and R 34 is a C 2-6 linear or branched alkylene group, preferably an ethylene group, a propylene group or a butylene group. Each of U 1 , U 2 and U 3 is a group containing a urethane bond in the molecular chain of the above polysiloxane macromonomer. In U 1 and U 3 , each of E 21 and E 22 is, as mentioned above, -CONH- or a bivalent group derived from a diisocyanate selected from the group consisting of saturated aliphatic, alicyclic and aromatic diisocyanates. In U 2 , E 24 is a bivalent group derived from a diisocyanate selected from the group consisting of saturated aliphatic, alicyclic and aromatic diisocyanates. Here, the bivalent group derived from a diisocyanate selected from the group consisting of saturated aliphatic, alicyclic and aromatic diisocyanates may, for example, be a saturated aliphatic diisocyanate such as ethylene diisocyanate, 1,3-diisocyanatepropane or hexamethylene diisocyanate; an alicyclic diisocyanate such as 1,2-diisocyanate cyclohexane, bis(4-isocyanatecyclohexyl)methane or isophorone diisocyanate; an aromatic diisocyanate such as tolylene diisocyanate or 1,5-diisocyanate naphthalene; or an unsaturated aliphatic diisocyanate such as 2,2'-diisocyanate diethylfumarate. Among them, hexamethylene diisocyanate, tolylene diisocyanate and isophorone diisocyanate are preferred, since they are relatively readily available, and they are capable of imparting mechanical strength. In U 1 , when E 21 is a -NHCO- group, X 21 is a covalent bond, and E 21 forms an urethane bond of the formula -OCO-NH- together with X 25 . Further, when E 21 is the above-mentioned bivalent group derived from a diisocyanate, X 21 is an oxygen atom or a C 1-6 alkylene glycol group, and E 21 forms an urethane bond together with X 21 and X 25 . X 25 is an oxygen atom or a C 1-6 alkylene glycol group, and R 32 is a C 1-6 linear or branched alkylene group. In U 2 , each of R 37 and R 38 is a C 1-6 linear or branched alkylene group. Each of X 27 and X 28 is an oxygen atom or a C 1-6 alkylene glycol group. E 24 is the above-mentioned bivalent group derived from a diisocyanate and forms an urethane bond together with X 27 and X 28 . In U 3 , R 33 is a C 1-6 linear or branched alkylene group, and X 26 is an oxygen atom or a C 1-6 alkylene glycol group. When E 22 is a -CONH- group, X 22 is a covalent bond, and E 22 forms a urethane bond of the formula -OCO-NH- together with X 26 . Further, when E 22 is the above-mentioned bivalent group derived from a diisocyanate, X 22 is an oxygen atom or a C 1-6 alkylene glycol group, and E 22 forms a urethane bond together with X 22 and X 26 . Here, the C 1-6 alkylene glycol for the above X 21 , X 25 , X 27 , X 28 , X 22 and X 26 may, for example, be a group of the formula (VIII): -O-(C x H 2x -O) y - wherein x is an integer of from 1 to 4, and y is an integer of from 1 to 5. In such a formula (VIII), if y is an integer of 6 or more, the oxygen permeability tends to be low, and the mechanical strength tends to deteriorate. Therefore, in the present invention, it is preferred that y is an integer of from 1 to 5, particularly preferably an integer of from 1 to 3. As mentioned above, each of S 1 and S 2 independently represents a group of the formula (V). In the formula (V), K is an integer of from 1 to 50, and L is an integer of from 0 to (50 - K). When K + L is larger than 50, the molecular weight of the polysiloxane macromonomer tends to be too large, and the compatibility thereof with an alkyl (meth)acrylamide tends to be poor, whereby there will be a tendency that it does not adequately dissolve when mixed, and turbidity will result during the polymerization, and it tends to be difficult to obtain a uniform transparent ocular lens material. Further, when it is 0, not only the oxygen permeability of the resulting ocular lens material tends to be low, but also the flexibility tends to be poor. K + L is preferably an integer of from 2 to 40, more preferably from 3 to 30. In the formula (I), the number n of the unit of the formula -(-S 1 -U 2 -)- is an integer of at least 1. Such n is preferably at most 3. If n is larger than 3, the minimum silicone chain necessary to secure the oxygen permeability necessarily tends to be too much in the molecule, whereby the compatibility with other copolymer component tends to be poor, and the resulting ocular lens material tends to have white turbidity. The above-mentioned alkyl (meth)acrylamide is a component which imparts transparency and lipid stain resistance to the resulting ocular lens material, improves the water absorptivity of the material and facilitates the cutting and grinding operations. Such an alkyl (meth)acrylamide may, for example, be N,N-dimethyl (meth)acrylamide, N,N-dimethylaminopropyl methacrylamide or N-isopropyl (meth)acrylamide. These may be used alone or in combination as a mixture of two or more of them. Among them, N,N-dimethylacrylamide is preferred in that it is thereby possible to obtain a water absorptive ocular lens material which is superior in the transparency and which can readily be processed by cutting or grinding. In this specification, the term "(meth)acrylamide" means "acrylamide and/or methacrylamide". The weight ratio of the above polysiloxane macromonomer to the alkyl (meth)acrylamide is usually from 10:90 to 90:10, preferably from 20:80 to 80:20, more preferably from 40:60 to 60:40. If the proportion of the polysiloxane macromonomer is smaller than the above range, the oxygen permeability of the resulting ocular lens material tends to be inadequate, the mechanical strength or rubber elasticity tends to be low, and the dimensional stability tends to be poor. On the other hand, if the proportion of the polysiloxane macromonomer exceeds the above range, the proportion of the alkyl (meth)acrylamide decreases relatively, whereby the resulting ocular lens material tends to be turbid, the surface tends to be tacky, a stain of e.g. lipid tends to easily adhere, the water absorptivity tends to be poor, and the cutting or grinding operation tends to be difficult. Further, it is desired that the total amount of the polysiloxane macromonomer and the alkyl (meth)acrylamide is at least 30% by weight, preferably at least 50% by weight, more preferably at least 60% by weight, based on the total amount of copolymer components. If such a total amount is less than 30% by weight, the resulting ocular lens material tends to be semihard, whereby the water absorptivity tends to be low, and such a material tends to be not suitable for soft contact lenses. In the present invention, a siloxane monomer selected from the group consisting of an organopolysiloxane-containing alkyl (meth)acrylate and an organopolysiloxane-containing styrene derivative may be used as a further copolymer component for the purpose of supplementally increasing the oxygen permeability and improving the mechanical strength. Such an organopolysiloxane-containing alkyl (meth)acrylate may, for example, be trimethylsiloxydimethylsilylmethyl (meth)acrylate, trimethylsiloxydimethylsilylpropyl (meth)acrylate, methylbis(trimethylsiloxy)silylpropyl (meth)acrylate, tris(trimethylsiloxy)silylpropyl (meth)acrylate, mono[methylbis(trimethylsiloxy)siloxy]bis trimethylsiloxy)silylpropyl (meth)acrylate, tris[methylbis(trimethylsiloxy)siloxy]silylpropyl (meth)acrylate, methylbis(trimethylsiloxy)silylpropylglyceryl (meth)acrylate, tris(trimethylsiloxy)silylpropylglyceryl (meth)acrylate, mono[methylbis(trimethysiloxy)siloxy]bis(trimethylsiloxy) silylpropylglyceryl (meth)acrylate, trimethylsilylethyltetramethyldisiloxypropylglyceryl (meth)acrylate, trimethylsilylmethyl (meth)acrylate, trimethylsilylpropyl (meth)acrylate, trimethylsilylpropylglyceryl (meth)acrylate, trimethysiloxydimethylsilylpropylglyceryl (meth)acrylate, methylbis(trimethylsiloxy)silylethyltetramethyldisiloxymethyl (meth)acrylate, tetramethyltriisopropylcyclotetrasiloxanylpropyl (meth)acrylate or tetramethyltriisopropylcyclotetrasiloxybis(trimethylsiloxy)silylpropyl (meth)acrylate. In this specification, "(meth)acrylate" means acrylate and/or methacrylate", and the same applies to other (meth)acrylate derivatives. The above-mentioned organopolysiloxane-containing styrene derivative may, for example, be a compound of the formula (IX): wherein p is an integer of from 1 to 15, q is 0 or 1, and r is an integer of from 1 to 15 (provided that a case where q=0 and r=0, is excluded). With respect to the organopolysiloxane-containing styrene derivative of the formula (IX), if p or r is an integer of 16 or more, synthesis and purification of such a derivative tend to be difficult, and the hardness of the resulting ocular lens material tends to be low, and if q is an integer of 2 or more, preparation of such an organopolysiloxane-containing styrene derivative tends to be difficult. Typical examples of the compound of the formula (IX) include tris(trimethylsiloxy)silylstyrene, bis(trimethylsiloxy)methylsilylstyrene, (trimethylsiloxy)dimethylsilylstyrene, tris(trimethylsiloxy)siloxydimethylsilylstyrene, [bis(trimethylsiloxy)methylsiloxy]dimethylsilylstyrene, (trimethylsiloxy)dimethylsilylstyrene, heptamethyltrisiloxanylstyrene, nonamethyltetrasiloxanylstyrene, pentadecamethylheptasiloxanylstyrene, heneicosamethyldecasiloxanylstyrene, heptacosamethyltridecasiloxanylstyrene, hentriacontamethylpentadecasiloxanylstyrene, trimethylsiloxypentamethyldisiloxymethylsilylstyrene, tris(pentamethyldisiloxy)silylstyrene, (tristrimethylsiloxy)siloxybis(trimethylsiloxy)silylstyrene, bis(heptamethyltrisiloxy)methylsilylstyrene, tris[methylbis(trimethylsiloxy)siloxy]silylstyrene, trimethylsiloxybis[tis(trimethylsiloxy)siloxy]silylstyrene, heptakis(trimethylsiloxy)trisiloxanylstyrene, nonamethyltetrasiloxyundecylmethylpentasiloxymethylsilylstyrene, tris[tris(trimethylsiloxy)siloxy]silylstyrene, tris(trimethylsiloxy)hexamethyltetrasiloxy(tristrimethylsiloxy)siloxytrimethylsiloxysilylstyrene, nonakis(trimethylsiloxy)tetrasiloxanylstyrene, bis(tridecamethylhexasiloxy)methylsilylstyrene, heptamethylcyclotetrasiloxanylstyrene, heptamethylcyclotetrasiloxybis(trimethylsiloxy)silylstyrene and tripropyltetramethylcyclotetrasiloxanylstyrene. These siloxane monomers may be used alone or in combination as a mixture of two or more of them. Among such siloxane monomers, an organopolysiloxane-containing alkyl (meth)acrylate such as tris(trimethylsiloxy)silylpropyl (meth)acrylate is preferably employed in that it is thereby at least possible to obtain an ocular lens material having good mechanical strength without decreasing the oxygen permeability. Further, an organopolysiloxane-containing styrene derivative such as tris(trimethylsiloxy)silylstyrene is preferably employed in that it is thereby possible to obtain an ocular lens material having excellent transparency and good mechanical strength within a wide range of its proportion and having a relatively high refractive index, and by virtue of the high refractive index, it is possible to prepare a thin ocular lens with the same power, whereby it is possible to obtain a contact lens having excellent oxygen permeability corresponding to the thickness being thin. It is advisable that the amount of such a siloxane monomer is not more than 70% by weight, preferably not more than 50% by weight, more preferably from 10 to 40% by weight, based on the total amount of copolymer components. If the amount of such a siloxane monomer exceeds 70% by weight, the total amount of the polysiloxane macromonomer and the alkyl (meth)acrylamide will be relatively small, whereby it tends to be difficult to obtain the desired ocular lens material of the present invention. On the other hand, such a siloxane monomer is preferably used at least 10% in order to adequately obtain the effect of the incorporation of such siloxane monomer. In the present invention, the copolymer is obtained by using the polysiloxane macromonomer and the alkyl (meth)acrylamide as main components and the siloxane monomer as a further copolymer component, as the case requires. However, a monomer having an unsaturated double bond copolymerizable with with such copolymer components may be used as an additional copolymer component. Such an additional copolymer component may be used for the purpose of imparting hardness or softness to the resulting ocular lens material, adjusting the water absorptivity of the material, imparting lipid stain resistance, imparting improved strength and durability by crosslinking, imparting an ultraviolet ray absorbing ability, or imparting a color. For example, in order to impart hardness, or softness or flexibility by adjusting the degree of hardness, one or more members may be selected for use among linear, branched or cyclic alkyl (meth)acrylates, alkoxyalkyl (meth)acrylates and alkylthioalkyl (meth)acrylates, such as methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, n-propyl (meth)acrylate, isobutyl (meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, n-decyl (meth)acrylate, n-dodecyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, t-pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, nonyl (meth)acrylate, stearyl (meth)acrylate, cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 3-ethoxypropyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 3-methoxypropyl (meth)acrylate, ethylthioethyl (meth)acrylate and methylthioethyl (meth)acrylate; styrene; α-methylstyrene; alkylstyrenes such as methylstyrene, ethylstyrene, propylstyrene, butylstyrene, t-butylstyrene, isobutylstyrene and pentylstyrene; and alkyl-α-methylstyrenes such as methyl-α-methylstyrene, ethyl-α-methylstyrene, propyl-α-methylstyrene, butyl-α-methylstyrene, t-butyl-α-methylstyrene, isobutyl-α-methylstyrene and pentyl-α-methylstyrene. The amount of such an additional copolymer component is usually not more than 60% by weight, preferably not more than 50% by weight, more preferably not more than 40% by weight, based on the total amount of copolymer components. If such an amount exceeds 60% by weight, the amount of the above polysiloxane macromonomer tends to be relatively small, whereby the oxygen permeability and the mechanical strength tend to be low. Further, in order to adjust the water absorptivity of the resulting ocular lens material, hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, hydroxybutyl (meth)acrylate and hydroxypropyl (meth)acrylate; (alkyl)aminoalkyl (meth)acrylates such as 2-dimethylaminoethyl (meth)acrylate and 2-butylaminoethyl (meth)acrylate; polyglycol mono(meth)acrylates such as propyleneglycol mono(meth)acrylate; vinylpyrrolidone; (meth)acrylic acid; maleic anhydride; fumaric acid; fumaric acid derivatives; aminostyrene and hydroxystyrene, may be used alone or in combination as a mixture of two or more. The amount of such an additional copolymer component is usually not more than 50% by weight, preferably not more than 30% by weight, more preferably not more than 20% by weight, based on the total amount of copolymer components. If such an amount exceeds 50% by weight, the amount of the polysiloxane macromonomer tends to be relatively small, whereby high oxygen permeability and high mechanical strength tend to be hardly expected. Further, in order to impart lipid stain resistance to the resulting ocular lens material, a fluorine-containing monomer of the formula (X): CH 2 =CR 7 COOC s H (2s-t+1) F t wherein R 7 is a hydrogen atom or CH 3 , s is an integer of from 1 to 15, and t is an integer of from 1 to (2s+1), may, for example, be employed. Specific examples of the monomer of the above formula (X) include 2,2,2-trifluoroethyl (meth)acrylate, 2,2,3,3-tetrafluoropropyl (meth)acrylate, 2,2,3,4,4,4-hexafluoro-t-hexyl (meth)acrylate, 2,2,3,4,4,4-hexafluorobutyl (meth)acrylate, 2,2,3,4,4,4-hexafluoro-t-hexyl (meth)acrylate, 2,3,4,5,5,5-hexafluoro-2,4-bis(trifluoromethyl)pentyl (meth)acrylate, 2,2,3,3,4,4-hexafluorobutyl (meth)acrylate, 2,2,2,2',2',2'-hexafluoroisopropyl (meth)acrylate, 2,2,3,3,4,4,4-heptafluorobutyl (meth)acrylate, 2,2,3,3,4,4,5,5-octafluoorpentyl (meth)acrylate, 2,2,3,3,4,4,5,5,5-nonafluoropentyl(meth)acrylate, 2,2,3,3,4,4,5,5,6,6,7,7-dodecafluoroheptyl (meth)acrylate, 3,3,4,4,5,5,6,6,7,7,8,8-dodecafluorooctyl (meth)acrylate, 3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl (meth)acrylate, 2,2,3,3,4,4,5,5,6,6,7,7,7-tridecafluoroheptyl (meth)acrylate, 3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10-hexadecafluorodecyl (meth)acrylate, 3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluorodecyl (meth)acrylate, 3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11-octadecafluoroundecyl (meth)acrylate, 3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,11-nonadecafluoroundecyl (meth)acrylate, and 3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12-eicosafluorododecyl (meth)acrylate. The amount of the above fluorine-containing monomer is usually not more than 40% by weight, preferably not more than 30% by weight, more preferably not more than 20% by weight, based on the total amount of copolymer components. If such an amount exceeds 40% by weight, the amount of the polysiloxane macromonomer tends to be relatively small, whereby high oxygen permeability and high mechanical strength tend to be hardly expected. Further, in order to impart improved mechanical strength and durability to the resulting ocular lens material, an additional copolymer component to be incorporated, may, for example, be a crosslinking agent such as ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, allyl (meth)acrylate, vinyl (meth)acrylate, trimethyrolpropane tri(meth)acrylate, methacryloyloxy ethyl acrylate, divinylbenzene, diallyl phthalate, diallyl adipate, triallyl isocyanurate, α-methylene-N-vinylpyrrolidone, 4-vinylbenzyl (meth)acrylate, 3-vinylbenzyl (meth)acrylate, 2,2-bis(p-(meth)acryloyloxyphenyl)hexafluoropropane, 2,2-bis(m-(meth)acryloyloxyphenyl)hexafluoropropane, 2,2-bis(o-(meth)acryloyloxyphenyl)hexafluoropropane, 2,2-bis(p-(meth)acryloyloxyphenyl)propane, 2,2-bis(m-(meth)acryloyloxyphenyl)propane, 2,2-bis(o-(meth)acryloyloxyphenyl)propane, 1,4-bis(2-(meth)acryloyloxyhexafluoroisopropyl)benzene, 1,4-bis(2-(meth)acryloyloxyhexafluoroisopropyl)benzene, 1,2-bis(2-(meth)acryloyloxyhexafluoroisopropyl)benzene, 1,4-bis(2-(meth)acryloyloxyisopropyl)benzene, 1,3-bis(2-(meth)acryloyloxyisopropyl)benzene or 1,2-bis(2-(meth)acryloyloxyisopropyl)benzene. These crosslinking agents may be used alone or in combination as a mixture of two or more. The amount of such a crosslinking agent is usually from 0.01 to 10 parts by weight, preferably from 0.05 to 8 parts by weight, more preferably from 0.1 to 5 parts by weight, per 100 parts by weight of the total amount of copolymer components. If the amount of the crosslinking agent is less than 0.01 part by weight, no adequate effects tend to be obtained by the incorporation of such such a crosslinking agent. On the other hand, if it exceeds 10 parts by weight, the material tends to be brittle. Further, in order to impart ultraviolet absorptivity or a color to the resulting ocular lens material, a polymerizable ultraviolet absorber, a polymerizable dyestuff or a polymerizable ultraviolet absorbing dyestuff may, for example, be used as an additional copolymer component. Specific examples of the polymerizable ultraviolet absorber include, for example, benzophenone type polymerizable ultraviolet absorbers such as 2-hydroxy-4-(meth)acryloyloxybenzophenone, 2-hydroxy-4-(meth)acryloyloxy-5-tert-butylbenzophenone, 2-hydroxy-4-(meth)acryloyloxy-2',4'-dichlorobenzophenone and 2-hydroxy-4-(2'-hydroxy-3'-(meth)acryloyloxypropoxy)benzophenone; benzotriazole type polymerizable ultraviolet absorbers such as 2-(2'-hydroxy-5'-(meth)acryloyloxyethylphenyl)-2H-benzotriazole, 2-(2'-hydroxy-5'-(meth)acryloyloxyethylphenyl)-5-chloro-2H-benzotriazole, 2-(2'-hydroxy-5'-(meth)acryloyloxypropylphenyl)-2H-benzotriazole and 2-(2'-hydroxy-5'-(meth)acryloyloxypropyl-3'-tert-butylphenyl)-5-chloro-2H-benzotriazole; salicylic acid derivative-type polymerizable ultraviolet absorbers such as phenyl 2-hydorxy-4-(meth)acryloyloxymethylbenzoate; and other polymerizable ultraviolet absorbers such as methyl 2-cyano-3-phenyl-3-(3'-(meth)acryloyloxyphenyl)propenoate. These polymerizable ultraviolet absorbers may be used alone or in combination as a mixture of two or more of them. Specific examples of the polymerizable dyestuff include, for example, azo type polymerizable dyestuffs such as l-phenylazo-4-(meth)acryloyloxynaphthalene, 1-phenylazo-2-hydroxy-3-(meth)acryloyloxynaphthalene, 1-naphthylazo-2-hydroxy-3-(meth)acryloyloxynaphthalene, 1-(α-anthrylazo)-2-hydroxy-3-(meth)acryloyloxynaphthalene, 1-((4'-(phenylazo)phenyl)azo)-2-hydroxy-3-(meth)acryloyloxynaphthalene, 1-(2',4'-xylylazo)-2-(meth)acryloyloxynaphthalene, 1-(o-tolylazo)-2-(meth)acryloyloxynaphthalene, 2-(m-(meth)acryloylamide-anilino)-4,6-bis(l'-(o-tolylazo)-2'-naphthylamino)-1,3,5-triazine, 2-(m-vinylanilino)-4-((4'-nitrophenylazo)-anilino)-6-chloro-1,3,5-triazine, 2-(1'-(o-tolylazo)-2'-naphthyloxy-4-(m-vinylanilino)-6-chloro-1,3,5-triazine, 2-(p-vinylanilino)-4-(1'-(o-tolylazo)-2'-naphthylamino)-6-chloro-1,3,5-triazine, N-(1'-(o-tolylazo)-2'-naphthyl)-3-vinylphthalic acid monoamide, N-(1'-(o-tolylazo)-2'-naphthyl)-6-vinylphthalic acid monoamide, 3-vinylphthalic acid-(4'-(p-sulfophenylazo)-1'-naphthyl)monoester, 6-vinylphthalic acid-(4'-(p-sulfophenylazo)-1'-naphthyl)monoester, 3-(meth)acryloylamide-4-phenylazophenol, 3-(meth)acryloylamide-4-(8'-hydroxy3',6'-disulfo-1'-naphthylazo)phenol, 3-(meth)acryloylamide-4-(1'-phenylazo-2'-naphthylazo)phenol, 3-(meth)acryloylamide-4-(p-tolylazo)phenol, 2-amino-4-(m-(2'-hydroxy-1'-naphthylazo)anilino)-6-isopropenyl-1,3,5-triazine, 2-amino-4-(N-methyl-p-(2'-hydroxy-1'-naphthylazo)anilino)-6-isopropenyl-1,3,5-triazine, 2-amino-4-(m-(4'-hydroxy-1'-phenylazo)anilino)-6-isopropenyl-1,3,5-triazine, 2-amino-4-(N-methyl-p-(4'-hydroxyphenylazo)anilino)-6-isopropenyl-1,3,5-triazine, 2-amino-4-(m-(3'-methyl-1'-phenyl-5'-hydroxy-4'-pyrazolylazo)anilino)-6-isopropenyl-1,3,5-triazine, 2-amino-4-(N-methyl-p-(3'-methyl-1'-phenyl-5'-hydroxy-4'-pyrazolylazo)anilino)-6-isopropenyl-1,3,5-triazine, 2-amino-4-(p-phenylazoanilino)-6-isopropenyl-1,3,5-triazine and 4-phenylazo-7-(meth)acryloylamide-l-naphthol; anthraquinone type polymerizable dyestuffs such as 1,5-bis((meth)acryloylamino)-9,10-anthraquinone, 1-(4'-vinylbenzoylamide)-9,10-anthraquinone, 4-amino-1-(4'-vinylbenzoylamide)-9,10-anthraquinone, 5-amino-1-(4'-vinylbenzoylamide)-9,10-anthraquinone, 8-amino-1-(4'-vinylbenzoylamide)-9,10-anthraquinone, 4-nitro-1-(4'-vinylbenzoylamide)-9,10-anthraquinone, 4-hydroxy-1-(4'-vinylbenzoylamide)-9,10-anthraquinone, 1-(3'-vinylbenzoylamide)-9,10-anthraquinone, 1-(2'-vinylbenzoylamide)-9,10-anthraquinone, 1-(4'-isopropenylbenzoylamide)-9,10-anthraquinone, 1-(3'-isopropenylbenzoylamide)-9,10-anthraquinone, 1-(2'-isopropenylbenzoylamide)-9,10-anthraquinone, 1,4-bis-(4'-vinylbenzoylamide)-9,10-anthraquinone, 1,4-bis-(4'-isopropenylbenzoylamide)-9,10-anthraquinone, 1,5-bis-(4'-vinylbenzoylamide)-9,10-anthraquinone, 1,5-bis-(4'-isopropenylbenzoylamide)-9,10-anthraquinone, 1-methylamino-4-(3'-vinylbenzoylamide)-9,10-anthraquinone, 1-methylamino-4-(4'-vinylbenzoyloxyethylamino)-9,10-anthraquinone, 1-amino-4-(3'-vinylphenylamino)-9,10-anthraquinone-2-sulfonic acid, 1-amino-4-(4'-vinylphenylamino)-9,10-anthraquinone-2-sulfonic acid, 1-amino-4-(2'-vinylbenzylamino)-9,10-anthraquinone-2-sulfonic acid, 1-amino-4-(3'-(meth)acryloylaminophenylamino)-9,10-anthraquinone-2-sulfonic acid, 1-amino-4-(3'-(meth)acryloylaminobenzylamino)-9,10-anthraquinone-2-sulfonic acid, 1-(β-ethoxycarbonylallylamino)-9,10-anthraquinone, 1-(β-carboxyallylamino)-9,10-anthraquinone, 1,5-di-(β-carboxyallylamino)-9,10-anthraquinone, 1-(β-isopropoxycarbonylallylamino)-5-benzoylamide-9,10-anthraquinone, 2-(3'-(meth)acryloylamide-anilino)-4- (3'- (3"-sulfo-4"-aminoanthraquinon-1"-yl)amino-anilino)-6-chloro-1,3,5-triazine, 2-(3'-(meth)acryloylamide-anilino)-4-(3'-(3"-sulfo-4"-aminoanthraquinon-1"-yl)amino-anilino)-6-hydrazino-1,3,5-triazine, 2,4-bis-((4"-methoxyanthraquinon-1"-yl)amino)-6-(3'-vinylanilino)1,3,5-triazine and 2-(2'-vinylphenoxy)-4-(4'-(3"-sulfo-4"-aminoanthraquinon-1"-yl-amino)anilino)-6-chloro-1,3,5-triazine; nitro type polymerizable dyestuffs such as o-nitroanilinomethyl (meth)acrylate; and phthalocyanine type polymerizable dyestuffs such as (meth)acryloyl-modified tetramino copper phthalocyanine and (meth)acryloyl-modified (dodecanoyl-modified tetraamino copper phthalocyanine). These polymerizable dyestuffs may be used alone or in combination as a mixture of two or more of them. Specific examples of the polymerizable ultraviolet absorbing dyestuff include, for example, benzophenone type polymerizable ultraviolet absorbing dyestuffs such as 2,4-dihydroxy-3-(p-styrenoazo)benzophenone, 2,4-dihydroxy-5-(p-styrenoazo)benzophenone, 2,4-dihydroxy-3-(p-(meth)acryloyloxymethylphenylazo)benzophenone, 2,4-dihydroxy-5-(p-(meth)acryloyloxymethylphenylazo)-benzophenone, 2,4-dihydroxy-3-(p-(meth)acryloyloxyethylphenylazo)benzophenone, 2,4-dihydroxy-5-(p-(meth)acryloyloxyethylphenylazo)benzophenone, 2,4-dihydroxy-3-(p-(meth)acryloyloxypropylphenylazo)benzophenone, 2,4-dihydroxy-5-(p-(meth)acryloyloxypropylphenylazo)benzophenone, 2,4-dihydroxy-3-(o-(meth)acryloyloxymethylphenylazo)benzophenone, 2,4-dihydroxy-5-(o-(meth)acryloyloxymethylphenylazo)benzophenone, 2,4-dihydroxy-3-(o-(meth)acryloyloxyethylphenylazo)benzophenone, 2,4-dihydroxy-5-(o-(meth)acryloyloxyethylphenylazo)benzophenone, 2,4-dihydroxy-3-(o-(meth)acryloyloxypropylphenylazo)benzophenone, 2,4-dihydroxy-5-(o-(meth)acryloyloxypropylphenylazo)benzophenone, 2,4-dihydroxy-3-(p-(N,N-di(meth)acryloyloxyethylamino)phenylazo)benzophenone, 2,4-dihydroxy-5-(p-(N,N-di(meth)acryloyloxyethylamino)phenylazo)benzophenone, 2,4-dihydroxy-3-(o-(N,N-di(meth)acryloyloxyethylamino)phenylazo)benzophenone, 2,4-dihydroxy-5-(o-(N,N-di(meth)acryloylethylamino)phenylazo)benzophenone, 2,4-dihydroxy-3-(p-(N-ethyl-N-(meth)acryloyloxyethylamino)phenylazo)benzophenone, 2,4-dihydroxy-5-(p-(N-ethyl-N-(meth)acryloyloxyethylamino)phenylazo)benzophenone, 2,4-dihydroxy-3-(o-(N-ethyl-N-(meth)acryloyloxyethylamino)phenylazo)benzophenone, 2,4-dihydroxy-5-(o-(N-ethyl-N-(meth)acryloyloxyethylamino)phenylazo)benzophenone, 2,4-dihydroxy-3-(p-(N-ethyl-N-(meth)acryloylamino)phenylazo)benzophenone, 2,4-dihydroxy-5-(p-(N-ethyl-N-(meth)acryloylamino)phenylazo)benzophenone, 2,4-dihydroxy-3-(o-(N-ethyl-N-(meth)acryloylamino)phenylazo)benzophenone and 2,4-dihydroxy-5-(o-(N-ethyl-N-(meth)acryloylamino)phenylazo)benzophenone; and benzoic acid type polymerizable ultraviolet absorbing dyestuffs such as phenyl 2-hydroxy-4-(p-styrenoazo)benzoate. These polymerizable ultraviolet absorbing dyestuffs may be used alone or in combination as a mixture of two or more of them. The amounts of the above-mentioned polymerizable ultraviolet absorber, polymerizable dyestuff and polymerizable ultraviolet absorbing dyestuff are substantially influenced by the thickness of the lens, and they are preferably not more than 3 parts by weight, more preferably from 0.1 to 2 parts by weight, per 100 parts by weight of the total amount of monomers to be subjected to polymerization. If the amount exceeds 3 parts by weight, the physical properties of the lens such as mechanical strength, tend to deteriorate. Further, in consideration of the toxicity of the ultraviolet absorber or dyestuff, such a material tends to be unsuitable as a material for ocular lenses such as contact lenses which are in direct contact with living tissues or intraocular lenses embedded in living bodies. Further, particularly in the case of a dyestuff, if the amount is too large, the color of the lens tends to be so deep that the transparency decreases, and visible rays tend to be hardly transmitted through the lens. The polysiloxane macromonomer and the alkyl (meth)acrylamide as well as the siloxane monomer and the additional copolymer components are suitably adjusted and subjected to copolymerization depending upon the particularly purpose of the desired ocular lens such as a contact lens or an intraocular lens. In the present invention, the polysiloxane monomer and the alkyl (meth)acrylamide as well as the siloxane monomer and the additional copolymer components which are used as the case requires, are adjusted to have the desired proportions within the above-mentioned ranges, and a radical polymerization initiator is added thereto, followed by polymerization by a usual method. The usual method may be a method of gradually heating the mixture after the addition of the radical polymerization initiator at a temperature within a range of from room temperature to about 120°C, or a method of irradiating electromagnetic waves such as microwaves, ultraviolet rays or radiation rays (γ-rays). In the case of the heat polymerization, the temperature may stepwisely be raised. The polymerization may be conducted by a bulk polymerization method or a solution polymerization method using e.g. a solvent, or it may be conducted by any other method. Specific examples of the radical polymerization initiator include, for example, azobisisobutylonitrile, azobisdimethylvaleronitrile, benzoyl peroxide, tert-butyl hydroperoxide and cumene hydroperoxide. These radical polymerization initiators may be used alone or in combination as a mixture of two or more of them. In a case where photopolymerization is employed, a photopolymerization initiator or sensitizer is preferably added. The above-mentioned polymerization initiator or sensitizer is incorporated usually in an amount of from about 0.001 to 2 parts by weight, preferably from 0.01 to 1 part by weight, per 100 parts by weight of the total amount of copolymer components. For the shaping of ocular lenses such as contact lenses or intraocular lenses, shaping methods commonly used by those skilled in the art may be employed. As such shaping methods, there may be mentioned, for example, a lathe cutting and grinding method and a molding method. The cutting and grinding method is a method in which the polymerization is conducted in a suitable mold or vessel to obtain a rod-, block- or plate-shaped base material (polymer), and then the base material is processed into a desired shape by mechanical processing such as cutting, grinding and polishing. The molding method is a method wherein a mold corresponding to the shape of a desired ocular lens is prepared, and the polymerization of the above-mentioned lens components is conducted in this mold to obtain a molded product, which may further be subjected to mechanical finishing treatment, if necessary. Apart from these methods, it is possible to employ a method for the present invention in which a monomer capable of forming a hard polymer is impregnated in a lens material, and then such a monomer is polymerized to harden the entirety, which is then subjected to cutting and grinding processing, and from a product processed to a desired shape, the hard polymer is removed to obtain a shaped product composed of the lens material (Japanese Unexamined Patent Publications No. 278024/1987 and No. 11854/1989). Further, when an intraocular lens is to be obtained, a supporting portion of the lens may be prepared separately from the lens and then attached to the lens, or it may be molded simultaneously (integrally) with the lens. Now, the ocular lens material of the present invention will be described in detail with reference to Examples. However, it should be understood that the present invention is by no means restricted to such specific Examples. PREPARATION EXAMPLE 1 Into a 500 ml four-necked flask equipped with a stirrer, a thermometer, a condenser and a dropping funnel, 168 g (0.2 mol) of a polydimethylsiloxane having one hydroxyl group at each terminal represented by the formula: 66.7 g (0.3 mol) of isophorone diisocyanate and 0.03 g of dibutyltin dilaurate were charged and stirred under a nitrogen stream at 50°C for two hours. This reaction solution was sampled, and a predetermined amount of di-n-butylamine was added thereto and mixed. Then, the amount of the remaining isocyanate groups was measured by a potentiometric titration method employing hydrochloric acid, whereupon the conversion was determined and found to be 100%. Then, 0.02 g of 2,6-di-tert-butyl-p-cresol was added to this reaction solution, and 28.6 g (0.22 mol) of hydroxyethyl methacrylate was dropwise added thereto over a period of 30 minutes using a dropping funnel at 50°C. Then, stirring was continued at 50°C for 4 hours, and then the conversion was determined in the same manner as described above and found to be 100%, whereby 262.5 g of a slightly yellow transparent viscous reaction product was obtained. The infrared absorption spectrum (IR) and the proton nuclear magnetic resonance spectrum ( 1 H-NMR) of this reaction product were measured and analyzed to confirm that a urethane bond-containing polysiloxane macromonomer of the formula: (hereinafter referred to as macromonomer A) was obtained. EXAMPLE 1 80 parts by weight of macromonomer A, 20 parts by weight of N,N-dimethylacrylamide, 0.5 part by weight of ethylene glycol dimethacrylate and 0.1 part by weight of 2,2'-azobis(2,4-dimethylvaleronitrile) as a polymerization initiator, were uniformly mixed to obtain a transparent solution. This solution was put into a glass test tube. Then, such a test tube was transferred into a circulation type constant-temperature bath and heated at 35°C for 40 hours and at 50°C for 8 hours. Then, it was transferred into an air circulating drier, and polymerization was conducted by raising the temperature to 110°C at a rate of 10°C per two hours to obtain a rod-shaped copolymer having a diameter of 13.5 mm. The obtained rod-shaped copolymer was subjected to hydration treatment and then cut into specimens having a thickness of 0.2 mm, which were then subjected to grinding and polishing treatment to obtain test specimens. Various physical properties of the test specimens were measured in accordance with the following methods. The results are shown in Table 1. (a) Transparency A test specimen in water was visually evaluated. Evaluation standards ○: Transparent Δ: Slightly turbid ×: Substantially turbid (b) Flexibility A test specimen was pulled from both sides, and the stretchability was examined. Evaluation standards ○: Very well stretched Δ: Not stretched very well ×: Not substantially stretched (c) Tackiness (lipid stain resistance) A test specimen was touched with a finger, and the releasability from the test specimen was examined. Evaluation standards ○: Finger readily released Δ: Finger slightly hardly released ×: Finger hardly released (d) Penetration strength By means of a penetration strength tester, a pressing needle having a diameter of 1/16 inch was pressed against the center of a test specimen, and the load (g) at the time of the breakage of the test specimen was measured. However, the values listed in Table 1 are values calculated as the thickness of the test specimen was 0.2 mm. (e) Elongation The elongation (%) at the time of the breakage of the test specimen in the above-mentioned measurement of the penetration strength, was measured. (f) Oxygen permeability coefficient (DK 0.2 ) The oxygen permeability coefficient of a test specimen was measured in a physiological saline at 35°C by means of Seikaken Type film oxygen permeability measuring instrument manufactured by Rika Seiki Kogyo Kabushiki Kaisha. The unit for oxygen permeability coefficient is ml (STP)·cm 2 /(cm 3 ·sec·mmHg). The oxygen permeability coefficients in Table 1 are numerical values obtained by multiplying the values of the oxygen permeability coefficients with the thickness of the test specimens being 0.2 mm by 10 11 . (g) Water content A test specimen was subjected to hydration treatment, and then the water content (%) of the test specimen was measured in accordance with the following equation: Water content (%) = W-Wo W × 100 where W is the weight (g) of the test specimen upon absorption of water to the equibrium state after the hydration treatment, and Wo is the weight (g) of the above-mentioned test specimen which was dried to the dried state in a drier after the hydration treatment. (h) Refractive index The refractive index was measured at a temperature of 25°C under a relative humidity of 50% by means of Atago refractometer 1T, manufactured by Kabushiki Kaisha Atago. EXAMPLES 2 TO 13 In the same manner as in Example 1, various components were blended to have compositions as identified in Table 1 and polymerized to obtain rod-shaped copolymers, which were then subjected to grinding and polishing treatment to obtain test specimens. Various physical properties of the obtained test specimens were examined in the same manner as in Example 1. The results are shown in Table 1. The abbreviations used in Table 1 have the following meanings: DMAA: N,N-dimethylacrylamide SiMA: Tris(trimethylsiloxy)silylpropyl methacrylate SiSt: Tris(trimethylsiloxy)silylstyrene EDMA: Ethylene glycol dimethacrylate V-65: 2,2'-azobis(2,4-dimethylvaleronitrile) It is evident from the results shown in Table 1 that the ocular lens materials of Examples 1 to 13 were obtained by using urethane bond-containing silicone macromonomers. Such macromonomers not only have urethane bonds at both terminals but also have urethane bonds optionally introduced at intermediate portions of the silicone chains, whereby such ocular lens materials have high oxygen permeability and high mechanical strength. Further, as they employ an alkyl (meth)acrylamide, they are also excellent in the transparency, the water content and the lipid stain resistance. Further, the ocular lens materials of Examples 4 to 13 further employ an organopolysiloxane-containing alkyl (meth)acrylate or an organopolysiloxane-containing styrene derivative, whereby it is evident that the mechanical strength and the oxygen permeability are further improved. COMPARATIVE EXAMPLE 1 A copolymer was prepared in the same manner as in Example 1 except that in Example 1, 80 parts by macromonomer B of the formula: was used instead of macromonomer A. However, such a copolymer was turbid and not suitable as an ocular lens material. COMPARATIVE EXAMPLE 2 A copolymer was prepared in the same manner as in Example 2 except that in Example 2, 50 parts of macromonomer B was used instead of macromonomer A. However, such a copolymer was turbid and not suitable as an ocular lens material. COMPARATIVE EXAMPLE 3 A copolymer was prepared in the same manner as in Example 3 except that in Example 3, 20 parts of macromonomer B was used instead of macromonomer A. However, such a copolymer was turbid and not suitable as an ocular lens material. The ocular lens material of the present invention provides the following effects. (a) The ocular lens material of the present invention is excellent in the transparency, and it provides an effect that it is suitable for use as an ocular lens. (b) The ocular lens material of the present invention is excellent in the oxygen permeability, and it provides an effect that when it is formed into a contact lens, it is free from impairing the metabolic function of cornea. (c) The ocular lens material of the present invention has practically adequate mechanical strength and relatively good rubber elasticity, and it provides an effect that it can be formed into a lens which is excellent in the dimensional stability and which is free from breakage against various physical treatments. (d) The ocular lens material of the present invention shows substantial water absorptivity (water content of at least 5% by weight), and it is soft in a hydrated state. Thus, it provides an effect that when formed into a contact lens, it gives comfortable feeling to the wearer, and when formed into an intraocular lens, it can be folded and inserted through a small incision of the eye ball without damaging the ocular tissues. (e) The ocular lens material of the present invention has little surface tackiness, and it has an effect that a stain of e.g. lipid scarcely adheres. (f) The ocular lens material of the present invention is relatively hard in a non-water containing state, and it has an effect that in such a state, cutting and grinding treatment can readily be applied thereto, and fine precision treatment can be applied thereto.

Claims: An ocular lens material made of a copolymer comprising, as main copolymer components, (A) a polysiloxane macromonomer having polymerizable groups bonded via one or more urethane bonds to the siloxane main chain, of the formula (I): A 1 -U 1 -(-S 1 -U 2 -) n -S 2 -U 3 -A 2 wherein A 1 is a group of the formula (II): Y 21 -R 31 - wherein Y 21 is an acryloyloxy group, a methacryloyloxy group, a vinyl group or an allyl group, and R 31 is a linear or branched alkylene group having from 2 to 6 carbon atoms; A 2 is a group of the formula (III): -R 34 -Y 22 wherein Y 22 is an acryloyloxy group, a methacryloyloxy group, a vinyl group or an allyl group, and R 34 is a linear or branched alkylene group having from 2 to 6 carbon atoms; U 1 is a group of the formula (IV): -X 21 -E 21 -X 25 -R 32 - wherein X 21 is a covalent bond, an oxygen atom or an alkylene glycol group having from 1 to 6 carbon atoms, E 21 is -CONH-, provided that in this case X 21 is a covalent bond and E 21 forms an an urethane bond together with X 25 , or a bivalent group derived from a diisocyanate selected from the group consisting of saturated aliphatic, alicyclic and aromatic diisocyanates, provided that in this case X 21 is an oxygen atom or an alkylene glycol group having from 1 to 6 carbon atoms and E 21 forms an urethane bond together with X 21 and X 25 , X 25 is an oxygen atom or an alkylene glycol group having from 1 to 6 carbon atoms, and R 32 is a linear or branched alkylene group having from 1 to 6 carbon atoms; each of S 1 and S 2 independently represents a group of the formula (V): wherein each of R 23 , R 24 , R 25 , R 26 , R 27 and R 28 independently represents an alkyl group having from 1 to 3 carbon atoms or a phenyl group, K is an integer of from 1 to 50, and L is an integer of from 0 to (50-K); U 2 is a group of the formula (VI): -R 37 -X 27 -E 24 -X 28 -R 38 - wherein each of R 37 and R 38 independently represents a linear or branched alkylene group having from 1 to 6 carbon atoms, each of X 27 and X 28 independently represents an oxygen atom or an alkylene glycol group having from 1 to 6 carbon atoms, and E 24 is a bivalent group derived from a diisocyanate selected from the group consisting of saturated aliphatic, alicyclic and aromatic diisocyanates provided that in this case E 24 forms an urethane bond together with X 27 and X 28 ; U 3 is a group of the formula (VII): -R 33 -X 26 -E 22 -X 22 - wherein R 33 is a linear or branched alkylene group having from 1 to 6 carbon atoms, X 22 is a covalent bond, an oxygen atom or an alkylene glycol group having from 1 to 6 carbon atoms, X 26 is an oxygen atom or an alkylene glycol group having from 1 to 6 carbon atoms, and E 22 is -CONH-, provided that in this case X 22 is a covalent bond and E 22 forms an urethane bond together with X 26 , or a bivalent group derived from a diisocyanate selected from the group consisting of saturated aliphatic, alicyclic and aromatic diisocyanates, provided that in this case X 22 is an oxygen atom or an alkylene glycol group having from 1 to 6 carbon atoms and E 22 forms an urethane bond together with X 22 and X 26 ; and n is an integer of at least 1; and (B) a vinyl comonomer, wherein the weight ratio of the polysiloxane macromonomer to the vinyl comonomer is from 10:90 to 90:10, characterised in that said vinyl comonomer is an alkyl (meth)acrylamide. The ocular lens material according to Claim 1, wherein the alkyl (meth)acrylamide is N,N-dimethyl methacrylamide. The ocular lens material according to Claim 1 or 2, wherein the copolymer contains, as a further copolymer component, a siloxane monomer selected from the group consisting of an organopolysiloxane-containing alkyl (meth)acrylate and an organopolysiloxane-containing styrene derivative, in an amount of not more than 70% by weight, based on the total amount of copolymer components. The ocular lens material according to Claim 3, wherein the siloxane monomer is an organopolysiloxane-containing styrene derivative. The ocular lens material according to Claim 3 or 4, wherein the organopolysiloxane-containing styrene derivative is tris(trimethylsiloxy)silylstyrene. The ocular lens material according to Claim 3, wherein the siloxane monomer is an organopolysiloxane-containing alkyl (meth)acrylate. The ocular lens material according to Claim 3 or 6, wherein the organopolysiloxane-containing alkyl (meth)acrylate is tris(trimethylsiloxy)silylpropyl (meth)acrylate.

Inventors: ANDO ICHIRO, ICHINOHE SHOJI, ITO ERI, IWATA NORIKO C, YAMAZAKI TOSHIO, YOKOYAMA YASUHIRO, ANDO, ICHIRO, ICHINOHE, SHOJI, ITO, ERI, IWATA, NORIKO, YAMAZAKI, TOSHIO, YOKOYAMA, YASUHIRO, Ando, Ichiro, c/o Menico Co.,Ltd., Ito, Eri, c/o Menicon Co., Ltd., Iwata, Noriko, c/o Menicon Co.,Ltd., Yokoyama, Yasuhiro, c/o Menicon Co.,Ltd.
Applicants: MENICON CO LTD, MENICON CO., LTD.
Application year: 1993
Main classification: G02B1
IPC codes: C08F290, G02B1, C08F299, G02C7, A61L27