Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2001-02-23
2003-08-05
Yoon, Tae H. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C523S106000, C523S108000, C528S028000, C351S16000R
Reexamination Certificate
active
06602930
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a material for contact lenses which is suitable as a polymer having biocompatibility and oxygen permeability, and to soft contact lenses. The soft contact lenses of the present invention have the water content of, for example, from 15 to 35%, and excellent flexibility and oxygen permeability.
2. Related Art
Clinical results have indicated that a use of contact lenses reduces the supply of oxygen from the air, which may sometimes cause inhibiting proliferation of corneal epithelial cells and corneal swelling. Accordingly, an improvement of the material in oxygen permeability has been attempted so far in order to provide contact lenses having higher safety.
In the improvement in oxygen permeability of hard contact lenses, introduction of siloxanyl methacrylate, fluoroalkyl methacrylate or the like has been attempted. This method remarkably improved oxygen permeability of hard contact lenses; however, the aggravation of the feel in use caused by the hard material has not be improved at all. On the other hand, soft contact lenses are categorized into no-water-containing soft contact lenses and water-containing (hydrogel) lenses. As for the no-water-containing soft contact lenses, silicone lenses, for example, have high oxygen permeability; however, too much elasticity causes lenses to stick to the cornea, and accordingly, they have not been practically utilized. Lenses made of (meth)acrylic esters have a rather low oxygen permeability constant, which is an insufficient value. The water-containing soft contact lenses are known to be comfortable in use due to flexibility of the material; however, their oxygen permeability is derived from the water content of the lenses, and thereby lower compared with that of hard contact lenses. For example, a material for water-containing soft lenses having the water content of 80% has the oxygen permeability constant of about 40×10
−11
(cm
2
/sec)·(mL O
2
/mL×mmHg).
A number of reports have been made with respect to the oxygen amount necessary for the cornea. Mishima compared the oxygen permeability of contact lenses with the corneal change in use, and reported that Dk/L of a contact lens corresponding to the cornea swelling ratio of 0 (the value obtained by dividing the Dk value (oxygen permeability) by the thickness of the lens (cm)) was not less than 70×10
−9
(Nichi-Kore-Shi 36: 1-12, 1994). The oxygen permeability of common soft contact lenses depends on the water content; accordingly, it is extremely difficult to prepare lenses satisfying the Dk/L value (oxygen transmissibility) of 70×10
−9
.
Accordingly, various siloxane-containing polymers have been disclosed in order to improve oxygen permeability of soft contact lenses. For example, Japanese Patent Laid-Open No. 294818/1991 (hereinafter referred to as prior art 1) discloses, as a soft contact lense having excellent oxygen permeability, low water-containing soft contact lenses which substantially comprise an organosiloxanyl (meth)acrylate, a fluorine-containing monomer and dimethylacrylamide as the main components. In this case, oxygen permeability may be improved by introducing silicone and the fluorine-containing monomer as the components of the contact lenses; however, the improvement is insufficient, and the resulting lenses are hard and poor in shape restorablility, which is caused by low molecule movability between a moiety having silicone group or fluorine group and a functional group (e.g., methacroyl group).
International Patent Publication (KOHYO) No.502949/1991 (hereinafter referred to as prior art 2) discloses soft contact lenses having excellent oxygen permeability which comprise a siloxane macromer as the main component. In this case, soft contact lenses having high oxygen permeability and excellent flexibility can be obtained by using a siloxane macromer having a high molecular weight as the main component. However, the macromer having the structure disclosed in the prior art 2 has the siloxane structure in the main chain and functional groups at the both ends, and thereby, the both ends of the macromer bind to other components in the polymer to inhibit the movability of the siloxane structure. Therefore, it cannot be actually expected to dramatically improve the oxygen permeability.
Accordingly, an object of the present invention is to provide a material for contact lenses and soft contact lenses having excellent flexibility and oxygen permeability.
The inventors of the present invention made intensive studies on the basis of the aforementioned prior arts in order to develop soft contact lenses having oxygen permeability in the same degree as or more than hard contact lenses. As a result, they successfully developed a material for soft contact lenses having satisfactory flexibility and oxygen permeability by using a siloxane macromer in which a polymerizing group binds to the polysiloxane side chain by means of urethane bond to maintain high movability of the siloxane structure which contributes to oxygen permeability in the polymer. The present invention was achieved on the basis of these findings.
SUMMARY OF THE INVENTION
The present invention relates to a material for contact lenses which comprises a copolymer essentially comprising a siloxane macromer of component (A) which has the number-average molecular weight of from about 1,000 to 10,000 and is represented by the general formula (I):
wherein R
1
, R
2
and R
3
are independently selected from C1-C4 alkyl groups; R
4
is selected from C1-C6 alkyl groups; R
5
is a residue obtained by removing NCO group from an aliphatic, alicyclic or aromatic diisocyanate; R
6
, R
7
, R
8
and R
9
are independently selected from C1-C3 alkylene groups; n is an integer of from 4 to 80; and m and p are independently an integer of from 3 to 40,
a water-insoluble monoolefin monomer of component (B), and a water-soluble monoolefin monomer of component (C).
The present invention further relates to a soft contact lens which is obtained by molding the aforementioned material for contact lenses in the shape of contact lens, and making the lens contain water.
In addition, the present invention relates to a soft contact lens which is obtained by injecting to a mold in the shape of contact lens a monomer mixture comprising a siloxane macromer of component (A) which has the number-average molecular weight of from about 1,000 to 10,000 and is represented by the general formula (I):
wherein R
1
, R
2
and R
3
are independently selected from C1-C4 alkyl groups; R
4
is selected from C1-C6 alkyl groups; R
5
is a residue obtained by removing NCO group from an aliphatic, alicyclic or aromatic diisocyanate; R
6
, R
7
, R
8
and R
9
are independently selected from C1-C3 alkylene groups; n is an integer of from 4 to 80; and m and p are independently an integer of from 3 to 40,
a water-insoluble monoolefin monomer of component (B), and a water-soluble monoolefin monomer of component (C); copolymerizing the monomer mixture; and making the resulting copolymer contain water.
DESCRIPTION OF PREFERRED EMBODIMENTS
The material for contact lenses of the present invention comprises a copolymer essentially comprising a siloxane macromer of component (A), a water-insoluble monoolefin monomer of component (B), and a water-soluble monoolefin monomer of component (C).
The siloxane macromer of component (A) is a component which may provide excellent flexibility and oxygen permeability, and the water-insoluble monoolefin monomer of component (B) and the water-soluble monoolefin monomer of component (C) are those which may provide properties corresponding to the purposes such as flexibility, oxygen permeability, and the desired water content. The material for contact lenses of the present invention comprises the copolymer components comprising these 3 components, thereby is a material for contact lenses having excellent flexibility and oxygen permeability, which have not been obtained in the conventional materials.
The siloxane macrome
Hoya Healthcare Corporation
Jacobson & Holman PLLC
Yoon Tae H.
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