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US 5,962,005 AGranted
Transparent cellulose hydrogel and production process thereof
AssigneeRengo Co., Ltd.
InventorsHiroshi Saga, Hidenao Saito
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AssigneeRengo Co., Ltd.
InventorsHiroshi Saga, Hidenao Saito
Estimating the term…
A transparent cellulose hydrogel having a transmittance of visible light of not less than 70%/mm and a tensile strength of not less than 10 kg/cm.sup.2, wherein the hydroxyl groups of cellulose constituting said hydrogel are not chemically crosslinked; and a process for producing a transparent cellulose hydrogel, comprising coagulation and regeneration of cellulose from a cellulose solution using an aqueous solution containing an organic solvent in a proportion of 20-95 wt %. The cellulose hydrogel of the present invention is useful as a raw material of an ophthalmic material, such as soft contact lens, artificial crystal lens, artificial cornea, artificial vitreous body and the like, a carrier of fragrance, and a base of gel and cream, and the like. In addition, the transparent cellulose hydrogel of the present invention has a densely packed and uniform structure, so that it can provide a material of a separation membrane having a small molecular cutoff and high pressure resistance.
A transparent cellulose hydrogel having a transmittance of visible light of not less than 70%/mm and a tensile strength of not less than 10 kg/cm.sup.2, wherein all of the hydroxyl groups of cellulose constituting said hydrogel are not chemically crosslinked.
A process for producing a transparent cellulose hydrogel, comprising coagulation and regeneration of cellulose from a cellulose solution using an aqueous solution containing at least one organic solvent selected from the group consisting of methanol, ethanol, acetonitrile, isopropyl alcohol, acetone, n-propyl alcohol and tetrahydrofuran, in a proportion of 30-90 wt % based on the weight of the aqueous solution.
A process for producing a transparent cellulose hydrogel, comprising coagulation and regeneration of cellulose from a viscose using an aqueous solution containing an organic solvent, which is a non-solvent for cellulose and is miscible with water, in a proportion of 50-95 wt % based on the weight of the aqueous solution, said aqueous solution containing a decomposition agent which decomposes cellulose xanthate into cellulose.
Dependencies are inferred from the claim text.
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Preparation of gels: containing an organic phase
Prostheses implantable into the body: eye parts, e.g. lenses or corneal implants; Artificial eyes
Lenses; Lens systems ; Methods of designing lenses: contact lenses for the eyes
Additional features; Implant or prostheses properties not otherwise provided for: transparent or translucent
Term ended 15 Apr 2018 (estimated)
USPTO file history isn’t available for this patent, so only indexed dates are shown.
The present invention relates to a transparent cellulose hydrogel and a process for production thereof. More particularly, the present invention relates to a transparent cellulose hydrogel useful as a raw material of an ophthalmic material, such as soft contact lens, artificial crystal lens, artificial cornea, artificial vitreous body and the like, a carrier of fragrance, a base of gel and cream, a material of separation membranes such as an ultrafiltration membrane and a dialysis membrane, and the like, and to a production process thereof.
Cellulose occurs naturally and has a high hydrophilicity. Thus, a hydrogel composed of this cellulose has superior biodegradability and biocompatibility, and has been widely used in various fields of food, cosmetics, medical supplies and the like. In addition, a transparent hydrogel material for soft contact lenses has been recently developed using a cellulose hydrogel.
Conventionally, various acrylate derivatives having a hydroxyl group have been used as a raw material of hydrated soft contact lenses. Of such derivatives, poly(2-hydroxyethyl methacrylate) (PHEMA) has been most often used in view of the relatively superior transparency and machinability. What influences the performance of a soft contact lens most is oxygen permeability coefficient. In the case of a hydrated soft contact lens, an increased water content can raise the oxygen permeability coefficient. However, PHEMA hydrogel achieves only about 38% water content.
The transparent cellulose hydrogel of the present invention comprises cellulose having hydroxyl groups that are not chemically crosslinked.
The hydroxyl groups which are not chemically crosslinked means that the hydroxy groups of cellulose are not chemically crosslinked by various crosslinking agents, and the gel is formed by physical crosslinking by the hydrogen bonding between the hydroxyl groups in cellulose.
In addition, the transparent cellulose hydrogel of the present invention has a transmittance of visible light of not less than 70%/mm.