Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Patent
1990-02-22
1993-01-05
Ryan, Patrick J.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
351160R, 525278, 264 11, 264 27, 428364, C08F23008, G02C 704
Patent
active
051771675
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. This invention relates to shaped articles having good transparency and high oxygen permeability, and to a process for producing the same.
2. Background Art
In recent years, contact lenses have been widely popularized as a means for correcting vision defects. This has created a demand for transparent materials having high oxygen permeability, because contact lenses having low oxygen permeability may cause anoxic damage to the cornea.
In response to the demand, shaped articles made from a random copolymer composed chiefly of siloxanyl methacrylate and methyl methacrylate are being used for hard contact lenses.
In order to impart sufficient oxygen permeability to this random copolymer, it is necessary to enhance the content of the silicone-containing component considerably. However, this unavoidably makes it difficult to shape the random copolymer into films, lenses and similar products. Moreover, the resulting shaped articles are not suited for practical purposes because of their relatively low tear strength and surface hardness. In practice, therefore, the content of the silicone-containing component is reduced in consideration of shapability and this makes it impossible to obtain shaped articles having sufficient oxygen permeability.
DISCLOSURE OF THE INVENTION
It is an object of the present invention to provide an oxygen-permeable shaped article which has sufficiently high oxygen permeability for use as an oxygen-permeable membrane, in at least one direction thereof, which has a high degree of transparency permitting it to be formed into contact lenses, and which also has excellent mechanical strength.
According to a first aspect of the present invention, there is provided an oxygen-permeable shaped article consisting of a block copolymer (a) of the general formula A--B, A--B--A or B--A--B where 80% by weight or more of the monomer units constituting segment A comprise an alkyl methacrylate having an alkyl group of 1 to 4 carbon atoms, 80% by weight or more of the monomer units constituting segment B comprise monomer units of the general formula methyl group or ##STR1## in which n is a whole number of 0 to 30, and the volume fraction of segment B is in the range of 30 to 70%, said shaped article being characterized in that of visible light, and (0.5.about.1).times.(V.sub.A .multidot.P.sub.A +V.sub.B .multidot.P.sub.B) where V.sub.A and P.sub.A represent the volume fraction and oxygen permeability coefficient, respectively, of the segment A component. and V.sub.B and P.sub.B represent the volume fraction and oxygen permeability coefficient, respectively, of the segment B component.
According to a second aspect of the present invention, there is provided an oxygen-permeable shaped article obtained by forming fibers consisting chiefly of a block copolymer (b) or graft copolymer (c) containing an organopolysiloxane as one component, and fusing or bonding a bundle of said fibers to unite them together.
BEST MODE FOR CARRYING OUT THE INVENTION
The first aspect of the present invention will be specifically described hereinbelow.
In the block copolymer (a) used in the first aspect of the present invention, 80% by weight or more, preferably 90% by weight or more, of the monomer units constituting segment A comprise an alkyl methacrylate having an alkyl group of 1 to 4 carbon atoms. Among the alkyl methacrylates having an alkyl group of 1 to 4 carbon atoms, methylmethacrylate is preferred.
The monomers which are copolymerizable with the aforesaid alkyl methacrylates and can constitute segment A include 2,2,2-trichloroethylmethacrylate, glycidyl methacrylate, allyl methacrylate, ethylene dimethacrylate and the like. The number average molecular weight of segment A is preferably in the range of 5,000 to 100,000. If the number average molecular weight is less than 5,000, the resulting shaped article may not have sufficient strength, while if it is greater than 100,000, the resulting shaped article will tend to show a reduction in transparency.
Segment B is such that 80% by weight or more of the m
REFERENCES:
patent: Re31406 (1983-10-01), Gaylord
patent: 4235985 (1980-11-01), Tanaka et al.
patent: 4242483 (1980-12-01), Novicky
patent: 4424328 (1984-01-01), Ellis
patent: 4540761 (1985-09-01), Kawamura et al.
patent: 4625007 (1986-11-01), Ellis et al.
patent: 4649185 (1987-03-01), Takamizawa et al.
patent: 4743667 (1988-05-01), Mizutani et al.
patent: 4861840 (1989-08-01), Lim et al.
patent: 5023305 (1991-06-01), Onozuka et al.
patent: 5057578 (1991-10-01), Spinelli
Patent Abstracts of Japan, vol. 13, No. 174 (C-589) (3522), Apr. 25, 1989, & JP-A-1 4640, Jan. 9, 1989, S. Tone, et al., "Block Copolymer Resin Composition".
Patent Abstracts of Japan, vol. 13, No. 174, (C-589) (3522) Apr. 25, 1989, & JP-A-1 4610, Jan. 9, 1989, M. Sugimori, et al., "Preparation of Block Copolymer".
WPIL/Derwent, accession No. 89-050148(07), Derwent Publications Ltd., & JP-A-1 006 013, Jan. 10, 1989.
Database WPIL, accession No. 86-066034 (10), Derwent Publications Ltd., & JP-A-61 018 402, Jan. 27, 1986.
Mori Hiroshi
Sugimori Masahiro
Takeda Haruko
Tone Seiji
Yamamoto Naoki
Gray Jill M.
Mitsubishi Rayon Co. Ltd.
Ryan Patrick J.
LandOfFree
Oxygen-permeable shaped articles and process for producing same does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Oxygen-permeable shaped articles and process for producing same, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Oxygen-permeable shaped articles and process for producing same will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2391242