Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From silicon reactant having at least one...
Reexamination Certificate
1999-09-16
2002-02-12
Moore, Margaret G. (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From silicon reactant having at least one...
C528S027000, C528S028000, C526S279000, C351S16000R
Reexamination Certificate
active
06346594
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an ocular lens material and a process for producing the same. More particularly, the present invention relates to an ocular lens material which shows, of course, excellent transparency, and which-as high oxygen permeability and is also excellent in deposit resistance and wettability to tears at the same time, and a process for easily producing the ocular lens material.
In recent years, as to optical materials, in particular, contact lens materials, it is thought that one of the causes of various ocular diseases is lowering of hydrophilic property (wettability to tears) of the lens surface or adhering of deposit such as protein or lipid. So, to highten hydrophilic property and deposit resistance is watched.
Conventionally, as a contact lens material showing water-absorptive property and excellent oxygen permeability, a material comprising a copolymer prepared by polymerizing a hydrophilic monomer such as 2-hydroxyethyl methacrylate or N,N-dimethylacrylamide with a fluorine-containing (meth)acrylate or a silicon-containing (meth)acrylate has been proposed in Japanese Unexamined Patent Publication No.121826/1994.
However, it is previously known that protein or lipid is accumulated on the matrix or to the inside of the above material comprising such copolymer.
On the other hand, hydrogel having high transparency and showing high preventing effect for adhesion of protein, comprising a copolymer prepared by introducing a zwitterionic group into a matrix made from a hydrophilic monomer such as 2-hydroxyethyl methacrylate has been proposed in Japanese Unexamined Patent Publication No.20814/1997.
However, oxygen permeability of the above hydrogel depends upon water content, so that its oxygen permeability never becomes higher than oxygen permeability of water.
As a rigid gas permeable contact lens material showing excellent oxygen permeability and non-water-absorptive property, a material comprising a copolymer prepared by polymerizing a fluorine-containing (meth)acrylate, a silicon-containing (meth)acrylate or a silicon-containing styrene derivative has been proposed in Japanese Examined Patent Publication No.55122/1987 and Japanese Patent No.2515010.
However, it is previously known that the above hard and high oxygen permeable material is poor in water retention on the surface thereof, and as a result, a patient uncomfort such as dry feeling in eyes is generated during wearing of lenses.
Then, it can be considered that a material showing excellent oxygen permeability and preventing effect for adhesion of lipid or protein can be produced from a copolymer prepared by polymerizing a zwitterionic group-containing monomer which can be expected to show high deposit resistance with a fluorine-containing (meth)acrylate or a silicon-containing (meth)acrylate, or a copolymer prepared by polymerizing a fluorine-containing (meth)acrylate into which a zwitterionic group is introduced or a silicon-containing (meth)acrylate into which a zwitterionic group is introduced.
However, the above zwitterionic group-containing monomer (intramolecular salt: betaine) is generally solid and extremely poor in solubility with not only various hydrophilic monomers but also, in particular, hydrophobic monomers. As a result, it is difficult that a transparent copolymer is prepared. In particular, the zwitterionic group-containing monomer cannot show solubility with a silicon-containing compound which is an essential component for an oxygen permeable material. Transparency is very important property for an optical material such as an ocular lens material. So, improvement of this solubility is important problem.
As a method for preparing a homogeneous copolymer by copolymerizing one monomer with the other monomer showing extremely poor solubility with the former monomer, such as 2-hydroxyethyl methacrylate with a silicon-containing (meth)acrylate, a method for improving solubility of monomers with each other by using a diluent such as an organic solvent is proposed in International Publication No.W097/09169.
However, as mentioned above, the zwitterionic group-containing monomer (intramolecular salt: betaine) is extremely poor in solubility with the organic solvent in addition to the hydrophobic monomer. For instance, the zwitterionic group-containing monomer shows solubility with only water, methanol and the like. On the other hand, a fluorine-containing (meth)acrylate and a silicon-containing (meth)acrylate cannot show solubility with water. When methanol or ethanol is used as a diluent, even if a monomer mixture solution is homogeneous and transparent, only opaque and phase-separated copolymers are prepared owing to volatilization of the diluent during polymerization.
A method for preparing a polymer film by casting a polymer solution of a siloxane-phosphorylcholine block copolymer which is a zwitterionic group-containing copolymer prepared by solution polymerization is proposed in Japanese Unexamined Patent Publication No.296019/1997.
However, the zwitterionic group-containing copolymer has a defect that it shows difficulty for dissolving in a solvent suitable for cast-coating owing to pseudo-crosslinking by positive and negative charge of a zwitterion. By this method, also, it is very difficult that a quite transparent copolymer is prepared.
An object of the present invention is to provide an ocular lens material which shows, of course, excellent transparency, and which has high oxygen permeability and also shows excellent deposit resistance such as preventing effect for adhesion of lipid or protein and excellent wettability to tears at the same time.
Another object of the present invention is to provide a process for easily producing the above ocular lens material which shows various excellent properties at the same time.
These and other objects of the present invention will become apparent from the description hereinafter.
SUMMARY OF THE INVENTION
In accordance with the present invention, there are provided an ocular lens material comprising a silicone compound having a zwitterionic group (I) represented by the formula (I):
wherein R
1
is hydrogen atom or a linear or branched alkyl group having 1 to 10 carbon atoms, in which two groups represented by R
1
may be the same or different with each other, R
2
is a linear or branched aliphatic hydrocarbon group having 1 to 12 carbon atoms or an aromatic hydrocarbon group, A
1
is —O—, —S—, —NH— or direct bond, A
2
is
A
3
is —O—, —S—, —NH— or ═O, in which when A
2
is —SOO
−
—, A
1
and A
3
are not —S—, and when A
3
is ═O, R
2
is absent, and each of p and q is independently an integer of 1 to 20; a zwitterionic group (II) represented by the formula (II):
wherein R
3
is hydrogen atom or a linear or branched alkyl group having 1 to 10 carbon atoms, in which two groups represented by R
3
may be the same or different with each other, A
4
is —O—, —S—, —NH— or direct bond, and each of r, s and t is independently an integer of 1 to 20; or a zwitterionic group (III) represented by the formula (III):
wherein R
4
is hydrogen atom or a linear or branched alkyl group having 1 to 10 carbon atoms, in which three groups represented by R
4
may be the same or different with each other, each of A
5
and A
6
is independently —O—, —S—, —NH— or direct bond, in which A
5
and A
6
are not direct bonds at the same time, and u is an integer of 1 to 20;
a process for producing an ocular lens material (hereinafter referred to as process (I)) comprising a silicone compound, characterized by preparing a prepolymer of the silicone compound by copolymerizing a monomer mixture containing a monomer (A-1) having a group represented by the formula (IV):
wherein R
6
is an alkylene group having 1 to 20 carbon atoms, and R
7
is a linear or branched alkyl group having 1 to 10 carbon atoms and a silicon-containing monomer, and
reacting the prepolymer of the silicone compound with a compound (B-1) which can react with the monomer (A-1) and impart —POO
−
, —SOO
−
or —COO
−
to a silicone compo
Baba Masaki
Watanabe Tsuyoshi
Armstrong Westerman Hattori McLeland & Naughton LLP
Menicon Co. Ltd.
Moore Margaret G.
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