Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
2001-11-07
2004-04-27
Moore, Margaret G. (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C351S16000R, C351S16000R
Reexamination Certificate
active
06727336
ABSTRACT:
TECHNICAL FIELD
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 suitably used for, for example, soft contact lens and soft intraocular lens, which is excellent not only in lipid-stain resistance, wettability and oxygen permeability, but also in flexibility, particularly, shape recovery at the same time, and a process for producing the ocular lens material.
BACKGROUND ART
Recently, consumer's demands for contact lenses, for example, are directed to a soft contact lens with high oxygen permeability, and for intraocular lenses, for example, a foldable intraocular lens. For these reasons, various materials having properties such as high oxygen permeability and excellent flexibility in particular are suggested.
For instance, a contact lens comprising a copolymer obtained by polymerizing siloxanyl (meth)acrylate and vinyl ester is disclosed in Japanese Unexamined Patent Publication No. 163811/1988, and a contact lens comprising a copolymer obtained by polymerizing siloxanyl (meth)acrylate, a vinyl ester, and vinyl (meth)acrylate and/or allyl (meth)acrylate is disclosed in Japanese Unexamined Patent Publication No. 301919/1988.
However, it cannot be said that these contact lenses are excellent in flexibility taking the monomer mixture into account though all of them have high oxygen permeability and excellent stain resistance.
In addition to the above, a water-containing contact lens obtained by saponifying a polymer comprising a (meth)acrylate polymer, which has at least one polymerizable group on average, a vinyl monomer, a vinyl ester of fatty acid and a crosslinkable monomer, is disclosed in Japanese Unexamined Patent Publication No. 102471/1994, and a silicone-containing hydrogel material formed from a polymer prepared by using a monomer mixture comprising a polysiloxane pre-polymer, a bulk polysiloxanylalkyl (meth)acrylate monomer and a hydrophilic monomer is disclosed in Japanese Unexamined Patent Publication No. 508063/1995. Also, in International Publication No. WO 97/09169, an ocular lens material obtained by hydrating, by using a water-soluble organic solvent, a polymer prepared by solution polymerization of a polymerizable silicon-containing compound and/or a polymerizable fluorine-containing compound, hydroxyalkyl (meth)acrylate, and a cross-linked compound is disclosed.
However, though these contact lenses and materials have properties such as high oxygen permeability, lipid-stain resistance and wettability, they only have one or a plurality of such properties, and do not show flexibility, particularly shape recovery, which is one of the important properties required for an ocular lens material, in particular, a soft ocular lens material.
As mentioned above, ocular lens materials having not only high oxygen permeability, excellent lipid-stain resistance and superior wettability but also shape recovery at the same time have not been provided yet. Accordingly, development of such materials as the above has been expected.
The present invention has been carried out from the viewpoint of the above prior arts. An object of the present invention is to provide an ocular lens material which has not only high oxygen permeability, excellent wettability and superior lipid-stain resistance, but also flexibility, particularly shape recovery at the same time, and an easy process for producing the ocular lens material.
DISCLOSURE OF INVENTION
The present invention relates to
(1) an ocular lens material comprising a siloxane-containing polymer obtained by polymerizing a monomer mixture containing
(A) a siloxane macromonomer having at least two active unsaturated groups and a number average molecular weight of 2,000 to 100,000; and
(B) a vinyl ester of lower fatty acid as essential components;
(2) an ocular lens material comprising a polymer prepared by saponifying a siloxane-containing polymer obtained by polymerizing a monomer mixture containing
(A) a siloxane macromonomer having at least two active unsaturated groups and a number average molecular weight of 2,000 to 100,000; and
(B) a vinyl ester of lower fatty acid as essential components; and
(3) a process for producing the above ocular lens material, characterized by preparing a siloxane-containing polymer by polymerization of a monomer mixture containing
(A) a siloxane macromonomer having at least two active unsaturated groups and a number average molecular weight of 2,000 to 100,000; and
(B) a vinyl ester of lower fatty acid as essential components; and then
subjecting said siloxane-containing polymer to saponification.
BEST MODE FOR CARRYING OUT THE INVENTION
The ocular lens material of the present invention, hereinafter referred to as an ocular lens material I, comprises a siloxane-containing polymer obtained by polymerizing a monomer mixture containing (A) a siloxane macromonomer having at least two active unsaturated groups and a number average molecular weight of 2,000 to 100,000; and (B) a vinyl ester of lower fatty acid as essential components.
The siloxane macromonomer (A) is a component which mainly imparts flexibility as typified by shape recovery and mechanical strength to the ocular lens material I.
The active unsaturated group in the siloxane macromonomer (A) is an active unsaturated group which can be subjected to radical polymerization. Examples of the active unsaturated group are (meth)acryloyl group, vinyl group, allyl group, (meth)acryloyloxy group, vinyl carbamate group and the like. Among these, acryloyloxy group and vinyl group are preferable from the viewpoint that they can impart excellent flexibility to the ocular lens material I and copolymerizability with other monomers is excellent.
In the instant specification, “(meth)acryl—” means “acryl— and/or methacryl—”.
It is desired that a number average molecular weight of the siloxane macromonomer (A) is at least 2,000, preferably at least 2,500 and more preferably at least 3,000 in order to impart excellent flexibility to the ocular lens material I without increasing hardness extremely. Also, it is desired that a number average molecular weight of the siloxane macromonomer (A) is at most 100,000, preferably at most 50,000, more preferably at most 10,000 not to make shape recovery inferior though the ocular lens material I becomes softened.
As the siloxane macromonomer (A), for example, the macromonomer of dialkyl siloxane having an active unsaturated group described in U.S. Pat. No. 4,189,546 specification can be used to obtain the aimed ocular lens material I.
Usually, many siloxane macromonomers are bad in wettability and relatively lack mechanical strength when each of the macromonomers is homopolymerized. Accordingly, as the siloxane macromonomer (A) used in the present invention, a siloxane macromonomer having a urethane group represented by the formula:
in the macromonomer structure is preferable in order to improve wettability.
When the siloxane macromonomer (A) contains the above urethane group, suitable mechanical strength and excellent wettability can be imparted to the ocular lens material I. It is desired that the number of the urethane group in the siloxane macromonomer (A) is at least 2, preferably at least 4 on average in order to impart sufficient mechanical strength and wettability. On the other hand, when too many urethane groups are introduced, flexibility of the ocular lens material I decreases. Therefore, it is desired that the average number of the urethane group in the siloxane macromonomer (A) is at most 20, preferably at most 14.
In the present invention, the macromonomer to which hydrophilic parts are introduced at the both ends of the siloxane structure described in U.S. Pat. No. 4,495,361 specification or U.S. Pat. No. 5,807,944 specification can also be used as the siloxane macromonomer (A) in order to obtain the ocular lens material I whose flexibility, particularly shape recovery, is improved.
In the present invention, as the siloxane macromonomer (A), a macromonomer represented by the formula (I-1) i
Ito Eri
Kawai Tetsuji
Nakada Kazuhiko
Nishibayashi Misako
Oono Sadanori
Menicon Co. Ltd.
Moore Margaret G.
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