Process for producing contact lens with hydrophilic surface and contact lens obtained thereby

A process for producing a contact lens having a hydrophilic surface comprising subjecting a contact lens material comprising a copolymer prepared by copolymerizing a monomer mixture containing a polymerizable monomer (A) which is at least one member selected from a sugar ketal-containing (meth)acrylate and a sugar glycerol ketal-containing (meth)acrylate, and a polymerizable monomer (B) which is copolymerizable with the polymerizable monomer (A) to acid treatment, wherein the polymerizable monomer (B) contains a hydrophobic monomer which is at least one member selected from a silicon-containing monomer, a fluorine-containing monomer and a silicon- and fluorine-containing monomer, and a contact lens which has high oxygen permeability and of which surface shows stably excellent hydrophilic property and which is excellent in deposit resistance at the same time.

TECHNICAL FIELD 
The present invention relates to a process for producing a contact lens 
having a hydrophilic surface and a contact lens produced by the process. 
More particularly, the present invention relates to a process for easily 
producing a contact lens which has high oxygen permeability, and of which 
surface shows stably excellent hydrophilic property for a long period of 
time, and which is excellent in deposit resistance such as lipid-deposit 
resistance, and relates to a contact lens having a hydrophilic surface, 
which is produced by the process. 
BACKGROUND ART 
In recent years, among various contact lenses, the demand for, in 
particular, contact lenses which can be continuously worn in eyes for a 
long period of time has become strong, so the development of various 
lenses has been proceeded. 
As to the above contact lens which can be continuously worn in eyes for a 
long period of time, it is known that excellent affinity of lens materials 
for ocular tissues, in particular, cornea tissues is important, in 
addition to the importance of excellent oxygen permeability. Accordingly, 
there have been carried out various researches in a contact lens which has 
high oxygen permeability and shows stably excellent affinity for ocular 
tissues for a long period of time. However, a contact lens satisfying the 
above properties has not been provided yet. 
In addition, lipid in lacrimal fluid easily adheres to, in particular, a 
water-absorptive contact lens, so there is a possibility that wearing 
comfort and transparency of the lens are lowered. Accordingly, it is 
desired that the lens is excellent in deposit resistance such as 
lipid-deposit resistance. 
As a non-water-absorptive contact lens having a water content of at most 
about 5% by weight, conventionally, there has been widely spread a contact 
lens comprising a copolymer prepared by polymerizing, as a main component, 
a (meth)acrylate monomer or a silicon-containing monomer. 
However, because such non-water-absorptive contact lens is substantially 
hydrophobic, the lens has defects that hydrophilic property of its surface 
is bad, its affinity for lacrimal fluid is poor and its wearing comfort is 
bad. 
The present invention has been accomplished in consideration of the above 
prior art, and aims at providing a process for easily producing a contact 
lens which has high oxygen permeability and of which surface shows stably 
excellent hydrophilic property for a long period of time, and which is 
excellent in deposit resistance such as lipid-deposit resistance, and 
providing a contact lens having a hydrophilic surface, which is produced 
by the process. 
DISCLOSURE OF THE INVENTION 
The present invention relates to a process for producing a contact lens 
having a hydrophilic surface, characterized by 
subjecting a contact lens material comprising a copolymer prepared by 
copolymerizing a monomer mixture containing 
(A) a polymerizable monomer which is at least one member selected from a 
sugar ketal-containing (meth)acrylate and a sugar glycerol 
ketal-containing (meth)acrylate, and 
(B) a polymerizable monomer which is copolymerizable with the polymerizable 
monomer (A) to acid treatment, 
wherein said polymerizable monomer (B) contains a hydrophobic monomer (X1) 
which is at least one member selected from 
a silicon-containing monomer represented by the formula (I): 
##STR1## 
in which p is an integer of 1 to 15, q is 0 or 1, and r is an integer of 
1 to 15; 
a fluorine-containing monomer represented by the formula (II): 
##STR2## 
in which R.sup.1 is hydrogen atom or methyl group, and R.sup.2 is a 
fluoroalkyl group having 1 to 10 carbon atoms or a group represented by 
the formula: 
##STR3## 
in which m is an integer of 1 to 3, and n is 0 or an integer of 1 to 7; 
and 
a silicon- and fluorine-containing monomer represented by the formula 
(III): 
##STR4## 
in which R.sup.3 is hydrogen atom or methyl group, each of R.sup.4 and 
R.sup.5 is independently methyl group or --O--Si(CH.sub.3).sub.3, and 
R.sup.6 is a fluoroalkyl group having 1 to 10 carbon atoms, which may have 
ether bond; and a contact lens having a hydrophilic surface produced by 
the above process. 
BEST MODE FOR CARRYING OUT THE INVENTION 
In the present invention, a contact lens having a hydrophilic surface can 
be produced by subjecting a contact lens material comprising a copolymer 
prepared by copolymerizing a monomer mixture containing 
(A) a polymerizable monomer which is at least one member selected from a 
sugar ketal-containing (meth)acrylate and a sugar glycerol 
ketal-containing (meth)acrylate, and 
(B) a polymerizable monomer which is copolymerizable with the polymerizable 
monomer (A) to acid treatment. Also, in the present invention, the above 
polymerizable monomer (B) contains a hydrophobic monomer (X1) which is at 
least one member selected from 
a silicon-containing monomer represented by the formula (I): 
##STR5## 
in which p is an integer of 1 to 15, q is 0 or 1, and r is an integer of 
1 to 15; 
a fluorine-containing monomer represented by the formula (II): 
##STR6## 
in which R.sup.1 is hydrogen atom or methyl group, and R.sup.2 is a 
fluoroalkyl group having 1 to 10 carbon atoms or a group represented by 
the formula: 
##STR7## 
in which m is an integer of 1 to 3, and n is 0 or an integer of 1 to 7; 
and 
a silicon- and fluorine-containing monomer represented by the formula 
(III): 
##STR8## 
in which R.sup.3 is hydrogen atom or methyl group, each of R.sup.4 and 
R.sup.5 is independently methyl group or --O--Si(CH.sub.3).sub.3, and 
R.sup.6 is a fluoroalkyl group having 1 to 10 carbon atoms, which may have 
ether bond. 
In the process of the present invention, it is one of great characteristics 
that the polymerizable monomer (A) which is at least one member selected 
from a sugar ketal-containing (meth)acrylate and a sugar glycerol 
ketal-containing (meth)acrylate is used. 
In the present specification, the terminology ". . . (meth)acrylate" means 
". . . acrylate and/or . . . methacrylate". The other (meth)acrylate 
derivative is the same meaning as this. 
The above polymerizable monomer (A) is a component which imparts excellent 
hydrophilic property which is stable for a long period of time to the 
surface of a contact lens and improves deposit resistance of a contact 
lens at the same time. 
Typical examples of the polymerizable monomer (A) are, for instance, a 
sugar ketal-containing (meth)acrylate such as 
1.2:3.4-di-O-isopropylidene-6-O-(meth)acryloyl-D-galactopyranoside 
(another name "1.2:3.4-di-O-isopropylidene-6-(meth)acryloyl-D-galactose") 
or 1.2:5.6-di-O-isopropylidene-3-O-(meth)acryloyl-D-glycofuranoside 
(another name "1.2:5.6-di-O-isopropylidene-3-O-(meth)acryloyl-D-glucose"); 
a sugar glycerol ketal-containing (meth)acrylate such as 
1.3-O-isopropylidene glycerol (meth)acrylate, 2.3-O-isopropylidene 
glycerol (meth)acrylate, 
2-methyl-2-ethyl-4-(meth)acryloyloxymethyl-1.3-dioxolane, 
2-methyl-2-isobutyl-4-(meth)acryloyloxy-1.3-dioxolane, 
2-methyl-2-phenyl-4-(meth)acryloyloxymethyl- 1.3-dioxolane or 
2-phenyl-4-(meth)acryloyloxymethyl-1.3-dioxolane; and the like. These can 
be used alone or in admixture thereof. Among them, 1.3-O-isopropylidene 
glycerol methacrylate and 2.3-O-isopropylidene glycerol methacrylate are 
particularly preferable from the viewpoint that effect of imparting 
hydrophilic property and effect of improving deposit resistance are great. 
It is desired that the amount of the polymerizable monomer (A) is at least 
1% by weight, preferably at least 3% by weight of the total amount of the 
monomer mixture, in order to sufficiently exhibit the effects of imparting 
hydrophilic property and improving deposit resistance, which are based on 
the use of the polymerizable monomer (A). It is desired that the amount of 
the polymerizable monomer (A) is at most 50% by weight, preferably at most 
30% by weight of the total amount of the monomer mixture, in order to 
sufficiently exhibit the effect of improving oxygen permeability. 
The monomer mixture used in the present invention contains, in addition to 
the above polymerizable monomer (A), the polymerizable monomer (B) which 
is copolymerizable with the polymerizable monomer (A). The polymerizable 
monomer (B) can form a contact lens material. 
In the process of the present invention, it is one of great characteristics 
that the polymerizable monomer (B) contains a hydrophobic monomer (X1) 
which is at least one member selected from 
a silicon-containing monomer represented by the formula (I): 
##STR9## 
in which p is an integer of 1 to 15, q is 0 or 1, and r is an integer of 
1 to 15; 
a fluorine-containing monomer represented by the formula (II): 
##STR10## 
in which R.sup.1 is hydrogen atom or methyl group, and R.sup.2 is a 
fluoroalkyl group having 1 to 10 carbon atoms or a group represented by 
the formula: 
##STR11## 
in which m is an integer of 1 to 3, and n is 0 or an integer of 1 to 7; 
and 
a silicon- and fluorine-containing monomer represented by the formula 
(III): 
##STR12## 
in which R.sup.3 is hydrogen atom or methyl group, each of R.sup.4 and 
R.sup.5 is independently methyl group or --O--Si(CH.sub.3).sub.3, and 
R.sup.6 is a fluoroalkyl group having 1 to 10 carbon atoms, which may have 
ether bond. 
The hydrophobic monomer (X1) is a component which improves oxygen 
permeability of a contact lens. Because the hydrophobic monomer (X1) is 
excellent in compatibility with the polymerizable monomer (A), 
copolymerization can be carried out in a good state, so that a contact 
lens having excellent transparency can be produced. 
As to the silicon-containing monomer represented by the formula (I), when p 
or r in the formula (I) is an integer of at least 16, there are tendencies 
that it is difficult to purify and synthesize the monomer and that 
hardness of the produced contact lens is lowered. When q in the formula 
(I) is an integer of at least 2, there is a tendency that it is difficult 
to synthesize the silicon-containing monomer. 
Typical examples of the silicon-containing monomer represented by the 
formula (I) are, for instance, tris(trimethylsiloxy)silylstyrene, 
bis(trimethylsiloxy)methylsilylstyrene, 
(trimethylsiloxy)dimethylsilylstyrene, 
tris(trimethylsiloxy)siloxydimethylsilylstyrene, 
[bis(trimethylsiloxy)methylsiloxy]dimethylsilylstyrene, 
heptamethyltrisiloxanylstyrene, nonamethyltetrasiloxanylstyrene, 
pentadecamethylheptasiloxanylstyrene, heneicosamethyldecasiloxanylstyrene, 
heptacosamethyltridecasiloxanylstyrene, 
trimethylsiloxypentamethyldisiloxymethylsilylstyrene, 
tris(pentamethyldisiloxy)silylstyrene, 
tris(trimethylsiloxy)siloxybis(trimethylsiloxy)silylstyrene, 
bis(heptamethyltrisiloxy)methylsilylstyrene, 
tri[methylbis(trimethylsiloxy)siloxy]silylstyrene, 
trimethylsiloxybis[tris(trimethylsiloxy)siloxy]silylstyrene, 
nonamethyltetrasiloxyundecylmethylpentasiloxymethylsilylstyrene, 
tris[tris(trimethylsiloxy)siloxy]silylstyrene, 
tris(trimethylsiloxyhexamethyl)tetrasiloxy-tris(trimethylsiloxy)siloxytrim 
ethylsiloxysilylstyrene, nonakis(trimethylsiloxy)tetrasiloxanylstyrene, 
bis(tridecamethylhexasiloxy)methylsilylstyrene, and the like. These can be 
used alone or in admixture thereof. 
Typical examples of the fluorine-containing monomer represented by the 
formula (II) are, for instance, 2,2,2-trifluoroethylstyrene, 
2,2,3,3-tetrafluoropropylstyrene, 2,2,3,3-tetrafluoro-t-pentylstyrene, 
2,2,3,4,4,4-hexafluorobutylstyrene, 2,2,3,4,4,4-hexafluoro-t-hexylstyrene, 
2,2,3,3,4,4-hexafluorobutylstyrene, 
2,2,2,2',2',2'-hexafluoroisopropylstyrene, 
2,2,3,3,4,4,4-heptafluorobutylstyrene, 
2,2,3,3,4,4,5,5-octafluoropentylstyrene, 
2,2,3,3,4,4,5,5,5-nonafluoropentylstyrene, 
4-vinylbenzyl-2',2'-2'-trifluoroethyl ether, 
4-vinylbenzyl-3',3',3'-trifluoropropyl ether, 
4-vinylbenzyl-4',4',4'-trifluorobutyl ether, 
4-vinylbenzyl-2',2',3',3',3'-pentafluoropropyl ether, 
4-vinylbenzyl-2',2',3',3',4',4',4'-heptafluorobutyl ether, 
4-vinylbenzyl-3',3',4',4',5',5',6',6',6'-nonafluorohexyl ether, 
4-vinylbenzyl-3',3',4',4',5',5',6',6',7',7',8',8',9'9,10',10',10'-heptadec 
afluorodecyl ether and the like. These can be used alone or in admixture 
thereof. 
Typical examples of the silicon- and fluorine-containing monomer 
represented by the formula (III) are, for instance, a 
fluoroalkyldimethylsilylstyrene such as fluoromethyldimethylsilylstyrene, 
difluoromethyldimethylsilylstyrene, trifluoromethyldimethylsilylstyrene, 
fluoropropyldimethylsilylstyrene, fluorohexyldimethylsilylstyrene, 
difluorohexyldimethylsilylstyrene, trifluorohexyldimethylsilylstyrene, 
tetrafluorohexyldimethylsilylstyrene, 
pentafluorohexyldimethylsilylstyrene, hexafluorohexyldimethylsilylstyrene, 
heptafluorohexyldimethylsilylstyrene, octafluorohexyldimethylsilylstyrene, 
nonafluorohexyldimethylsilylstyrene, decafluorooctyldimethylsilylstyrene, 
tridecafluorooctyldimethylsilylstyrene, 
tetradecafluorooctyldimethylsilylstyrene or 
heptadecafluorooctyldimethylsilylstyrene; 
a fluoroalkylbis[trimethylsiloxy]silylstyrene such as 
trifluoromethylbis[trimethylsiloxy]silylstyrene, 
heptafluoropropylbis[trimethylsiloxy]silylstyrene, 
decafluorooctylbis[trimethylsiloxy]silylstyrene, 
tridecafluorooctylbis[trimethylsiloxy]silylstyrene, 
tetradecafluorooctylbis[trimethylsiloxy]silylstyrene or 
heptadecafluorooctylbis[trimethylsiloxy]silylstyrene; 
a fluoroalkylmethyltrimethylsiloxysilylstyrene such as 
trifluoromethylmethyltrimethylsiloxysilylstyrene, 
difluoromethylmethyltrimethylsiloxysilylstyrene, 
trifluoromethylmethyltrimethylsiloxysilylstyrene, 
heptafluoropropylmethyltrimethylsiloxysilylstyrene, 
tridecafluorohexylmethyltrimethylsiloxysilylstyrene, 
decafluoroocrylmethyltrimethylsiloxysilylstyrene, 
tridecafluorooctylmethyltrimethylsiloxysilylstyrene or 
heptadecafluorooctylmethyltrimethylsiloxysilylstyrene; 
an alkoxy group-containing fluorostyrene derivative such as 
trifluoromethoxydifluoromethyldimethylsilylstyrene, 
methoxydifluoromethyldimethylsilylstyrene, 
trifluoromethoxytetrafluoroethyldimethylsilylstyrene, 
heptafluoroethoxydifluoroethyldimethylsilylstyrene or 
trifluoromethoxydifluoromethylmethyltrimethylsiloxysilylstyrene; and the 
like. These can be used alone or in admixture thereof. 
The hydrophobic monomer (X1) is, as mentioned above, at least one member 
selected from the silicon-containing monomer represented by the formula 
(I), the fluorine-containing monomer represented by the formula (II) and 
the silicon- and fluorine-containing monomer represented by the formula 
(III). However, part of the hydrophobic monomer (X1) can be varied to a 
compound such as a silicon-containing styrene derivative other than the 
above monomers, such as heptamethylcyclotetrasiloxanylstyrene, 
heptamethylcyclotetrasiloxybis(trimethylsiloxy)silylstyrene or 
tripropyltetramethylcyclotetrasiloxanylstyrene; or a fluorine-containing 
silicone such as [(CH.sub.3).sub.3 SiO].sub.3 Si(CH.sub.2).sub.2 
--C(CF.sub.3).sub.2 --O--CO--CH.dbd.CH.sub.2, [(CH.sub.3).sub.3 SiO].sub.3 
Si(CH.sub.2).sub.2 --C(CF.sub.3).sub.2 --O--CO--C(CH.sub.3).dbd.CH.sub.2, 
[(CH.sub.3).sub.3 SiO].sub.3 Si(CH.sub.2).sub.3 --C(CF.sub.3).sub.2 
--O--CO--CH.dbd.CH.sub.2 or [(CH.sub.3).sub.3 SiO].sub.3 
Si(CH.sub.2).sub.3 --C(CF.sub.3).sub.2 --O--CO--C(CH.sub.3).dbd.CH.sub.2. 
It is desired that the amount of the hydrophobic monomer (X1) is at least 
10% by weight, preferably at least 30% by weight of the total amount of 
the monomer mixture, in order to sufficiently improve oxygen permeability 
of a contact lens. It is desired that the amount of the hydrophobic 
monomer (X1) is at most 99% by weight, preferably at most 90% by weight of 
the total amount of the monomer mixture, in order to sufficiently exhibit 
the effects of imparting hydrophilic property and improving deposit 
resistance. 
In the process of the present invention, in order to more improve deposit 
resistance of a contact lens, the polymerizable monomer (B) can contain, 
as a hydrophobic monomer, a fluoroalkyl (meth)acrylate (X2) having an 
alkyl group having 1 to 12 carbon atoms, in which at least one hydrogen 
atom is substituted with fluorine atom. 
Typical examples of the fluoroalkyl (meth)acrylate (X2) are, for instance, 
2,2,2-trifluoroethyl (meth)acrylate, 2,2,3,3-tetrafluoropropyl 
(meth)acrylate, 2,2,3,3-tetrafluoro-t-pentyl (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-octafluoropentyl (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, 
3,3,4,4,5,5,6,6,7,7,8,8,9,9,11,10,10-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, 
3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12-eicosafluorododecyl 
(meth)acrylate and the like. These can be used alone or in admixture 
thereof. 
It is desired that the amount of the fluoroalkyl (meth)acrylate (X2) is at 
least 1% by weight, preferably at least 5% by weight of the total amount 
of the monomer mixture, in order to sufficiently exhibit the effect of 
improving deposit resistance of a contact lens. It is desired that the 
amount of the fluoroalkyl (meth)acrylate (X2) is at most 90% by weight, 
preferably at most 80% by weight of the total amount of the monomer 
mixture, in order to sufficiently exhibit the effect of imparting 
hydrophilic property. 
In the process of the present invention, in order to adjust hardness of a 
contact lens and improve mechanical strength of a contact lens, the 
polymerizable strength of a contact lens, the polymerizable monomer (B) 
may contain a hydrophobic monomer (X3) other than the above hydrophobic 
monomer(X1) and the fluoroalkyl (meth)acrylate (X2). 
Typical examples of the hydrophobic monomer (X3) are, for instance, a 
linear, branched or cyclic alkyl (meth)acrylate such as methyl 
(meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, n-propyl 
(meth)acrylate, isobutyl (meth)acrylate, n-butyl (meth)acrylate, t-butyl 
(meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, 
n-decyl (meth)acrylate, n-dodecyl (meth)acrylate, n-pentyl (meth)acrylate, 
t-pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, 
nonyl (meth)acrylate, stearyl (meth)acrylate, cyclopentyl (meth)acrylate 
or cyclohexyl (meth)acrylate; an alkoxyalkyl (meth)acrylate such as 
2-ethoxyethyl (meth)acrylate, 3-ethoxypropyl (meth)acrylate, 
2-methoxyethyl (meth)acrylate or 3-methoxypropyl (meth)acrylate; an 
alkylthioalkyl (meth)acrylate such as ethylthioethyl (meth)acrylate or 
methylthioethyl (meth)acrylate; styrene; .alpha.-methylstyrene; an 
alkylstyrene such as methylstyrene, ethylstyrene, propylstyrene, 
butylstyrene, t-butylstyrene, isobutylstyrene or pentylstyrene; an 
alkyl-.alpha.-methylstyrene such as methyl-.alpha.-methylstyrene, 
ethyl-.alpha.-methylstyrene, propyl-.alpha.-methylstyrene, 
butyl-.alpha.-methylstyrene, t-butyl-.alpha.-methylstyrene, 
isobutyl-.alpha.-methylstyrene or pentyl-.alpha.-methylstyrene; a 
silicon-containing (meth)acrylate such as 
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(trimethylsiloxy)siloxy]bis(trimethylsiloxy)silylpropylglyce 
ryl (meth)acrylate, trimethylsilylethyltetramethyldisiloxypropylglyceryl 
(meth)acrylate, trimethylsilylmethyl (meth)acrylate, trimethylsilylpropyl 
(meth)acrylate, trimethylsilylpropylglyceryl (meth)acrylate, 
trimethylsiloxydimethylsilylpropylglyceryl (meth)acrylate, 
methylbis(trimethylsiloxy)silylethyltetramethyldisiloxymethyl 
(meth)acrylate, tetramethyltriisopropylcyclotetrasiloxanylpropyl 
(meth)acrylate or 
tetramethyltripropylcyclotetrasiloxybis(trimethylsiloxy)silyipropyl 
(meth)acrylate; and the like. These can be used alone or in admixture 
thereof. 
It is desired that the amount of the hydrophobic monomer (X3) is at least 
0.1% by weight, preferably at least 0.5% by weight of the total amount of 
the monomer mixture, in order to sufficiently exhibit the effects of 
adjusting hardness and improving mechanical strength, which are based on 
the use of the hydrophobic monomer (X3). It is desired hat the amount of 
the hydrophobic monomer (X3) is at most 70% by eight, preferably at most 
50% by weight of the total amount of the monomer mixture, in order to 
sufficiently exhibit the effects of imparting hydrophilic property and 
improving deposit resistance. 
In the process of the present invention, in order to impart 
water-absorptive property to a contact lens and more improve hydrophilic 
property of the surface of a contact lens, the polymerizable monomer (B) 
can contain a hydrophilic monomer (Y). 
Typical examples of the hydrophilic monomer (Y) are, for instance, a 
hydroxyl group-containing (meth)acrylate such as hydroxyethyl 
(meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, 
dihydroxypropyl (meth)acrylate, dihydroxybutyl (meth)acrylate, diethylene 
glycol mono(meth)acrylate, triethylene glycol mono(meth)acrylate, 
propylene glycol mono(meth)acrylate or dipropylene glycol 
mono(meth)acrylate; (meth)acrylic acid; a (meth)acrylamide monomer such as 
(meth)acrylamide, N-methyl(meth)acrylamide, N-ethyl(meth)acrylamide, 
N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide or 
N,N-methylethyl(meth)acrylamide; a vinyl lactam such as 
N-vinylpyrrolidone, N-vinylpiperidone, N-vinylcaprolactam or 
N-vinylcapryllactam; an aminoalkyl (meth)acrylate such as aminoethyl 
(meth)acrylate, N-methylaminoethyl (meth)acrylate, N,N-dimethylaminoethyl 
(meth)acrylate or 2-butylaminoethyl (meth)acrylate; an alkoxyl 
group-containing (meth)acrylate such as methoxyethyl (meth)acrylate, 
ethoxyethyl (meth)acrylate or methoxydiethylene glycol (meth)acrylate; 
maleic anhydride; maleic acid; fumaric acid; a fumaric acid derivative; 
aminostyrene; hydroxystyrene; and the like. These can be used alone or in 
admixture thereof. Among them, because the effect of improving hydrophilic 
property is great, at least one member selected from (meth)acrylic acid, a 
(meth)acrylamide monomer and a vinyl lactam is preferable. 
It is desired that the amount of the hydrophilic monomer (Y) is at least 
0.1% by weight, preferably at least 0.5% by weight of the total amount of 
the monomer mixture, in order to sufficiently exhibit the effect of 
improving hydrophilic property. It is desired that the amount of the 
hydrophilic monomer (Y) is at most 20% by weight, preferably at most 15% 
by weight of the total amount of the monomer mixture, in order to 
sufficiently exhibit the effect of improving oxygen permeability and 
deposit resistance. 
The process of the present invention can be preferably used for producing a 
non-water-absorptive contact lens having a water content of at most about 
5% by weight, which is bad in hydrophilic property. It is desired that the 
above hydrophobic monomer (X) ((X1)-(X3)) and the above hydrophilic 
monomer (Y) which are examples of the polymerizable monomer (B) are 
suitably selected so that the non-water-absorptive contact lens can be 
preferably produced. 
In the process of the present invention, in order to improve mechanical 
strength of a contact lens and impart durability to a contact lens, the 
polymerizable monomer (B) can contain a crosslinkable monomer (Z). 
Typical examples of the crosslinkable monomer (Z) are, for instance, 
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, diallyl fumarate, allyl 
(meth)acrylate, vinyl (meth)acrylate, trimethylolpropane 
tri(meth)acrylate, methacryloyloxyethyl (meth)acrylate, divinylbenzene, 
diallyl phthalate, diallyl adipate, triallyldiisocyanate, 
.alpha.-methylene-N-vinylpyrrolidone, 4-vinylbenzyl (meth)acrylate, 
3-vinylbenzyl (meth)acrylate, 
2,2-bis((meth)acryloyloxyphenyl)hexafluoropropane, 
2,2-bis((meth)acryloyloxyphenyl)propane, 
1,4-bis(2-(meth)acryloyloxyhexafluoroisopropyl)benzene, 
1,3-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, 
1,2-bis(2-(meth)acryloyloxyisopropyl)benzene and the like. These can be 
used alone or in admixture thereof. 
It is desired that the amount of the crosslinkable monomer (Z) is at least 
0.01% by weight, preferably at least 0.05% by weight of the total amount 
of the monomer mixture, in order to sufficiently exhibit the effects of 
improving mechanical strength and imparting durability. It is desired that 
the amount of the crosslinkable monomer (Z) is at most 10% by weight, 
preferably at most 7% by weight of the total amount of the monomer 
mixture, in order to prevent a contact lens from becoming brittle. 
In the process of the present invention, at first, the monomer mixture 
containing the polymerizable monomer (A) and the polymerizable monomer (B) 
is copolymerized to give a copolymer. 
In order to copolymerize the monomer mixture, usual polymerization methods 
can be employed. For instance, after a radical polymerization initiator is 
added to the monomer mixture to give a mixture, the mixture is gradually 
heated within the range of room temperature to about 130.degree. C., or 
the mixture is irradiated with electromagnetic wave such as microwave, 
ultraviolet ray or radiation (.gamma. ray). During the thermal 
polymerization, the temperature of the mixture may be raised stepwise. The 
copolymerization may be carried out by a bulk polymerization method, a 
solution polymerization method using a solvent or the other polymerization 
method. 
Typical examples of the radical polymerization initiator are, for instance, 
azobisisobutyronitrile, azobisdimethylvaleronitrile, benzoyl peroxide, 
t-butyl hydroperoxide, cumene hydroperoxide and the like. These can be 
used alone or in admixture thereof. In the case that the copolymerization 
is carried out utilizing electromagnetic wave, it is desired that a 
photopolymerization initiator and a polymerization sensitizer are further 
added to the above mixture. It is desired that the amount of the 
photopolymerization initiator and the polymerization sensitizer is 0.002 
to 2 parts by weight (hereinafter referred to as part(s)), preferably 0.01 
to 1 part based on 100 parts of the total amount of the monomer mixture. 
The thus obtained copolymer is formed into a contact lens shape. 
A method for forming the copolymer into a contact lens shape is not 
particularly limited. Various forming methods which are usually used by a 
person skilled in the art can be employed. Examples of the forming method 
are, for instance, a cutting and processing method, a molding method and 
the like. In the cutting and processing method, after the above 
copolymerization is carried out in a suitable mold or container to give a 
material (copolymer) having a shape of bar, block or plate, the material 
is formed into the desired shape by mechanical process such as cutting 
process or polishing process. In the molding method, the above monomer 
mixture is copolymerized in a mold having a shape corresponding to the 
desired contact lens shape to give a molded article (contact lens 
mateiral), and then, as occasion demands, the molded article is subjected 
to mechanical finishing process. A combined method of the cutting and 
processing method with the molding method can be also employed. 
In the present invention, in addition to these methods, a method disclosed 
in Japanese Unexamined Patent Publication No. 278041/1987 and Japanese 
Unexamined Patent Publication No. 11854/1989 can be employed. In this 
method, a hard polymer is impregnated with a copolymerizable component for 
a lens material and then, the copolymerizable component is copolymerized 
to give a material which is further hardened as a whole. The material is 
subjected to cutting process to give a molded article having the desired 
shape and then, the above hard polymer is removed from the molded article 
to give a molded article (contact lens material) comprising a lens 
material. 
The thus obtained contact lens material is subjected to acid treatment, so 
that the contact lens having a hydrophilic surface of the present 
invention can be produced. 
That is, the above contact lens material composed of the copolymer is 
subjected to acid treatment with each of organic acids and inorganic 
acids, so that ketal group in the copolymer is converted into hydroxyl 
group (so-called deketal reaction). For instance, as shown by the 
following reaction formula, isoprpylidene group is removed by the 
hydrolysis, so that hydrophilic property is imparted to the copolymer. 
##STR13## 
In the process of the present invention, the contact lens material is 
subjected to acid treatment. The contact lens material may be a copolymer 
prepared by copolymerizing the monomer mixture, which has a shape of 
block, plate or bar and which is not formed into the desired shape, and 
may be a processed article produced from the copolymer by the cutting and 
processing method and/or molding method, which has the desired contact 
lens shape. 
Examples of an acid used for the acid treatment are, for instance, 
hydrochloric acid, sulfuric acid, phosphoric acid, acetic acid, formic 
acid, trifluoroacetic acid and the like. In the case that concentration of 
the acid used for the acid treatment is high, there are dangers that a 
contact lens material becomes an inferior material and that crack is 
generated in a contact lens material. Accordingly, the acid treatment may 
be carried out by increasing concentration of the acid in a treating 
solution gradually or stepwise. The suitable acid content of the treating 
solution and the suitable immersing time of a contact lens material vary 
according to quality of a non-treated contact lens material and kind of 
the acid, so they cannot be unconditionally defined. It is preferred that, 
in general, the contact lens material is subjected to the acid treatment 
using the treating solution having an acid content of about 0.1 to 99 w/v 
% at room temperature for about 1 minute to 24 hours. In the case that the 
non-treated contact lens material comprises a copolymer prepared without 
using a hydrophilic monomer and is not impregnated with a humectant, crack 
is easily generated in the contact lens material due to excitement of a 
sudden deketal reaction. Accordingly, the acid treatment may be carried 
out, in particular, by increasing concentration of the acid in the 
treating solution gradually or stepwise. 
The reaction in the acid treatment is not strictly limited to a standard 
treating method and a standard treating time. This acid treatment can be 
reproducibly carried out within a constant permissible range, so it can be 
particularly utilized industrially. 
The thus acid treated contact lens may be subjected to neutralization 
treatment by immersing in an alkaline aqueous solution such as sodium 
carbonate aqueous solution, or can be subjected to immersing treatment or 
boiling treatment in water or physiological sodium chloride solution. 
As mentioned above, in accordance with the process of the present 
invention, there can be easily produced a contact lens which has high 
oxygen permeability, and of which surface shows stably excellent 
hydrophilic property for a long period of time, and which is excellent in 
deposit resistance such as lipid-deposit resistance. 
The process for producing a contact lens having a hydrophilic surface and 
the contact lens produced by the process of the present invention are more 
specifically explained by means of the following Examples, and it is to be 
understood that the present invention is not limited to the Examples.

EXAMPLES 1 TO 6 AND COMATIVE EXAMPLE 1 
A monomer mixture and a polymerization initiator which were shown in TABLE 
1 were mixed and dissolved with each other to give a mixture. The mixture 
was dropped into a test tube and then, the copolymerization was carried 
out at 30.degree. C. for 16 hours, at 40.degree. C. for 24 hours and at 
50.degree. C. for 8 hours in a constant temperature water bath. Then, the 
curing was carried out at 50.degree. C. for 5 hours in a circulating 
drier, and then followed with raising the temperature of the content in 
the test tube from 50.degree. to 120.degree. C. at a rate of 10.degree. 
C./1.5 hours. Furthermore, after the annealing treatment was carried out 
at 120.degree. C. for 1 hour, the content in the test tube was gradually 
cooled to room temperature to give a transparent copolymer having a shape 
of bar. The copolymer was cut into a contact lens shape by an ordinary 
method to give a test piece having a thickness of 0.2 mm and a test piece 
having a thickness of 4 mm. 
Then, the acid treatment was carried out by immersing the test piece in HCl 
solution having a concentration of 6 mol/l for 1 hour, so that ketal group 
in the copolymer was converted into hydroxyl group (deprotection). The 
acid treated test piece was observed with naked eyes. As a result, the 
test piece was colorless and transparent. 
Then, physical properties of the test pieces produced in EXAMPLES 1 to 6 
were examined in accordance with the following methods. The results are 
shown in TABLE 2. 
(1) Oxygen Permeability 
Using Seikaken-type film oxygen-gas permeator made by RIKASEIKI KOGYO CO., 
LTD., oxygen permeability of the acid treated test piece having a 
thickness of 0.2 mm was measured in physiological sodium chloride solution 
at 35.degree. C. 
The unit of oxygen permeability is (cm.sup.2 /sec).(mlO.sub.2 
/(ml.multidot.mmHg)), and the numerical value shown in TABLE 2 was 
obtained by multiplying the original value by 10.sup.11 times. 
(2) Contact Angle 
Before the acid treatment, just after the acid treatment or after allowing 
for stand for 1 week in an atmosphere (room temperature), contact angle 
(degree) of the test piece having a thickness of 4 mm was measured at 
25.degree. C. by air-bubble method. 
Each code listed in TABLE 1 shows the following compound. 
IPGMA: 2.3-O-Isopropylidene glycerol methacrylate 
SiSt: Tris(trimethylsiloxy)silylstyrene 
6FP: 2,2,2,2',2',2'-Hexafluoroisopropyl methacrylate 
N-VP: N-Vinyl-2-pyrrolidone 
MAA: Methacrylic acid 
VBMA: 4-Vinylbenzyl methacrylate 
EDMA: Ethylene glycol dimethacrylate 
V-65: 2,2'-Azobis(2,4-dimethylvaleronitrile) 
TABLE 1 
__________________________________________________________________________ 
Polymerization 
initiator 
Monomer mixture (parts) part/100 parts of 
Polymerizable 
Polymerizable monomer (B) total amount of 
EXAMPLE 
monomer (A) 
Hydrophobic monomer (X) 
Hydrophilic monomer (Y) 
Crosslinkable monomer (Z) 
monomer mixture 
NO. IPGMA SiSt 6FP N-VP MAA VBMA EDMA V-65 
__________________________________________________________________________ 
1 5 51 54 -- -- 6 1 0.1 
2 10 46 54 -- -- 6 1 0.1 
3 10 60 40 -- -- 6 1 0.1 
4 10 70 30 -- -- 6 1 0.1 
5 20 46 44 -- -- 6 1 0.1 
6 10 46 44 5 5 6 1 0.1 
COM. EX. 1 -- 46 54 5 5 6 1 0.1 
__________________________________________________________________________ 
TABLE 2 
______________________________________ 
Physical properties of test piece 
Contact angle (degree) 
Just After allowing 
EXAMPLE Oxygen Before acid after acid for stand 
NO. permeability treatment treatment for 1 week 
______________________________________ 
1 114 86 40 52 
2 114 72 26 42 
3 115 81 25 38 
4 120 84 28 38 
5 89 78 24 37 
6 94 58 18 20 
______________________________________ 
From the results shown in TABLE 2, it can be understood that all test 
pieces produced in EXAMPLES 1 to 6 have high oxygen permeability. It can 
be understood that contact angle of each test piece, measured just after 
acid treatment is remarkably smaller than contact angle measured before 
acid treatment, so excellent hydrophilic property is imparted to each test 
piece. Furthermore, it can be understood that though each test piece is 
allowed to stand for 1 week, contact angle of each test piece does not 
very increase, and excellent hydrophilic property of each test piece is 
maintained. 
Then, lipid-deposit resistance of the acid treated test pieces produced in 
EXAMPLE 2 and COMATIVE EXAMPLE 1 was measured in accordance with the 
following method. 
(3) Lipid-deposit Resistance 
There were mixed 0.3 g of oleic acid, 0.3 g of linolic acid, 4.0 g of 
tripalmitin, 1.0 g cetyl alcohol, 0.3 g of palmitic acid, 4.0 g of 
spermaceti, 0.4 g of cholesterol, 0.4 g of cholesterol palmitate and 14.0 
g of yolk lecithin with each other to give an artificial ocular lipid 
(buffer solution of pH 7). The acid treated test piece "Ss" was immersed 
in the artificial ocular lipid at 37.degree. C. for 5 hours and washed 
with flowing water. Then, lipid which adhered to the test piece "Ss" was 
extracted with 1 ml of a mixture solution of ethanol with ether (ethanol: 
ether=3:1 (volume ratio)) to give a lipid extract. To 500 .mu.l of the 
lipid extract was added 1 ml of concentrated sulfuric acid and then, 3 mg 
of vanillin and 2 ml of phosphoric acid were added thereto to give an 
extract mixture. Then, using a spectrophotometer (made by Japan 
Spectroscopic Co., Ltd., UV-3100), absorbance of the extract mixture at a 
wavelength of 540 nm was measured. The absorbance was shown as "As". 
As to the acid treated test piece "Sc" which was not immersed in the 
artificial ocular lipid, the extraction of lipid and the measurement of 
absorbance were carried out in the same manner as to the acid treated test 
piece "Ss" which was immersed in the artificial ocular lipid. The 
absorbance was shown as "Ac". 
The adhering lipid amount per unit weight (Q (mg/g)) was calculated in 
accordance with the following equation. 
EQU Q=12.1654 (Ks-Kc)-0.0523 
In the above equation, 
##EQU1## 
As a result, the adhering lipid amount of the test piece in EXAMPLE 2 was 
0.114 mg/cm.sup.2, compared to 0.240 mg/cm.sup.2 in COMATIVE EXAMPLE 1. 
The amount in EXAMPLE 2 was at most half the amount in COMATIVE EXAMPLE 
1. From these results, it can be understood that the test piece produced 
in accordance with the process of the present invention in EXAMPLE 2 is 
extremely excellent in lipid-deposit resistance. 
INDUSTRIAL APPLICABILITY 
In accordance with the process of the present invention there can be easily 
produced a contact lens which has high oxygen permeability, and of which 
surface shows stably excellent hydrophilic property for a long period of 
time, and which is excellent in deposit resistance such as lipid-deposit 
resistance. 
Because the contact lens having a hydrophilic surface of the present 
invention, which is produced by the above process has the above properties 
at the same time, it can be utilized as various contact lenses, 
particularly as non-water-absorptive contact lenses.