Contact lens
A contact lens excellent in optical property, offering favorable feeling during the use thereof, and capable of continuous uses, which is composed of a hard portion in the central part and a soft portion in the periphery of the central part is provided. The contact lens comprising two kinds of polymers and having a hard portion arranged in the central part thereof and a soft portion arranged in the periphery of the central part, wherein a monomer mixture forming the hard portion contains at least one silicone-containing monomer, and the monomer mixture forming the hard portion and a monomer mixture forming the soft portion each contain at least one common hydrophilic monomer.
1. A contact lens comprising two kinds of polymers and having a hard portion arranged in the central part of the contact lens and a soft portion arranged in the periphery of the central part, wherein a monomer mixture forming said hard portion contains at least one silicone-containing monomer, wherein the contact lens contains at least one common hydrophilic monomer in the monomer mixture forming said hard portion and a monomer mixture forming said soft portion, said common hydrophilic monomer being a monomer having not less than 5% of a water content as a homopolymer thereof, and wherein the contact lens has an oxygen permeation coefficient (D k ) of at least 64×10 −11 (cm 2 /sec)·(mLO 2 /(mL×mmHg)).
2. The contact lens of claim 1 , wherein a water content of a homopolymer of a hydrophilic monomer having the maximum water content in the monomer mixture forming said hard portion does not exceed a water content of a homopolymer of a hydrophilic monomer having the maximum water content in the monomer mixture forming said soft portion.
3. The contact lens of claim 2 , wherein a weight ratio of the hydrophilic monomer which provides the homopolymer having the maximum water content in the monomer mixture forming said hard portion to the whole polymerization components in the monomer mixture forming said hard portion does not exceed a weight ratio of the hydrophilic monomer which provides the homopolymer having the maximum water content in the monomer mixture forming said soft portion to the whole polymerization components in the monomer mixture forming said soft portion, and a weight ratio of the whole hydrophilic monomers contained in the monomer mixture forming said hard portion to the whole polymerization components in the monomer mixture forming said hard portion does not exceed a weight ratio of the whole hydrophilic monomers contained in the monomer mixture forming said soft portion to the whole polymerization components in the monomer mixture forming said soft portion.
4. The contact lens of claim 1 , wherein a ratio of a water content of a homopolymer of the hydrophilic monomer commonly contained in the monomer mixture forming said hard portion and the monomer mixture forming said soft portion to a water content of a copolymer obtained by polymerizing the monomer mixture forming said soft portion is not more than 2.
5. The contact lens of claim 1 , wherein the hydrophilic monomer commonly contained in the monomer mixture forming said hard portion and the monomer mixture forming said soft portion is selected from the group consisting of hydroxymethyl (meth)acrylate, hydroxyethyl (meth)acrylate, hydroxybutyl (meth)acrylate, and hydroxypropyl (meth)acrylate.
6. A contact lens comprising two kinds of polymers and having a hard portion arranged in the central part of the contact lens and a soft portion arranged in the periphery of the central part, wherein a monomer mixture forming said hard portion contains at least one silicone-containing monomer, and the monomer mixture forming said hard portion and a monomer mixture forming said soft portion each contain at least one common hydrophilic monomer, wherein said silicone-containing monomer is a styrene which has a silane or a siloxane bond and is represented by the general formula (I):
(wherein l is 0 or 1, and n and m are integers of 1 to 15).
7. The contact lens of claim 6 , wherein said styrene having the silane or the siloxane bond represented by the general formula (I) is tris(trimethylsiloxy)silylstyrene (l=0, n=4).
8. The contact lens of claim 1 , wherein said silicone-containing monomer is a (meth)acrylate which has a siloxane bond and is represented by the general formula (II):
(wherein R 1 is H or CH 3 , m is an integer of 1 to 5, and n is an integer of 1 to 15).
9. The contact lens of claim 8 , wherein said meth(acrylate) having the siloxane bond represented by the general formula (II) is tris(trimethylsiloxy)silylpropyl acrylate (R 1 =H, m=3, n=4) or tris(trimethylsiloxy)silylpropyl methacrylate (R 1 =CH 3 , m=3, n=4).
10. The contact lens of claim 1 , wherein in a joint part between the hard portion and the soft portion the hard portion-forming monomer mixture is impregnated into a copolymer obtained by polymerizing the soft portion-forming mixture.