Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Patent
1997-02-05
1997-12-16
Schofer, Joseph L.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
525296, C08F26710
Patent
active
056986360
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an ocular lens material and a process for producing the same, and more particularly to an ocular lens material which can be preferably used for ocular lenses such as high water-absorptive contact lenses, and a process for producing the same.
BACKGROUND ART
In the nineteen-nineties, in a field of toiletries such as menstrual goods and paper napkin, a field of medical articles such as artificial skin, artificial muscle and water-absorptive contact lenses, and a field of articles for foods, such as wrapping materials for keeping freshness of foods, a high water-absorptive polymer is more widely developed as a new functional material. Particularly, in the field of medical articles, a contact lens material composed of high water-absorptive hydrogel is preferably used from the viewpoint of good sensation of wearing, easiness of adaptation to eyes (good adaptation to organisms) and the like.
However, the thus contact lens material composed of hydrogel which is insoluble in water and shows high water-absorptive property has a problem that mechanical property is suddenly lowered in accordance with the increase of water content. Also, on the contrary, the contact lens material has a problem that gas permeability is lowered in accordance with the lowering of water content. Accordingly, it is desired that hydrogel which is sufficiently satisfied with gas permeability and mechanical property at the same time is developed.
In the thus situation, there is developed a polymer obtained by using N,N-dimethylacrylamide, such as a (meth)acrylic acid alkyl ester-N,N-dimethylacylamide copolymer.
The above-mentioned polymer shows good transparency and water soluble. However, in the polymer, water-absorptive property which should be originally heightened by N,N-dimethylacrylamide and mechanical strength which should be originally heightened by a (meth)acrylic acid alkyl ester are counterbalanced with each other. Accordingly, the polymer has a problem that water-absorptive property and mechanical strength are not sufficient.
In order to solve the above-mentioned problem, there are proposed, for instance, polymerizable group by using a (meth)acrylic acid alkyl ester, and then, copolymerizing the polymer with N,N-dimethylacrylamide (Japanese Examined Patent Publication No. 29091/1993), component for introducing a specific reactive group into a molecule of the obtained polymer, and copolymerizing a copolymer obtained by reacting a monomer having reactivity with the reactive group in the obtained polymer with the above-mentioned polymer, with N,N-dimethylacrylamide (Japanese Examined Patent Publication No. 81612/1992), immersing the prepared polymers in a molecular chain network and intertwining with each other (Inter Penetrate Network), comprising polymerizing a hydrophilic monomer with a hydrophobic monomer by using a crosslinking agent which easily crosslinks with these monomers (Japanese Examined Patent Publication No. 23271/1984),
However, in the above-mentioned methods (1) and (2), there are problems that it is difficult to prepare the polymer having a polymerizable group and that its process is complicated.
In the above-mentioned producing method (3), in order to sufficiently exhibit properties which should be originally exhibited by a hydrophilic and a monomer hydrophobic monomer, a hydrophilic monomer and a hydrophobic monomer which respectively have different polymerizable groups are used so that each of monomers separately polymerizes. For instance, a monomer having vinyl group, such as N-vinyl pyrrolidone is used as a hydrophilic monomer, and a hydrophobic monomer such as methyl methacrylate is used as a hydrophobic monomer. However, in the method, there are problems that the above-mentioned monomer having vinyl group easily remains without polymerizing and that non-crosslinked N-vinyl pyrrolidone polymer easily elutes because the vinyl group shows, as usual, low polymerizability.
For instance, as a method for producing an ocular lens such as a contact lens from an ocula
Cheng Wu C.
Schofer Joseph L.
Tomey Technology Corporation
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