UV absorbing polymer

Details UV absorbing polymer UV absorbing polymer

1999-07-07

2001-06-26

Gorr, Rachel (Department: 1711)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

From reactant having at least one -n=c=x group as well as...

C528S085000, C522S002000, C522S007000, C522S063000, C522S904000, C522S905000

Reexamination Certificate

active

06252032

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to polymers having improved ultraviolet (UV) absorption. More specifically, the present invention relates to UV absorbing polymers suitable for use in a wide variety of applications, including the production of thin film electrochemical sensors of the type used, for example, in subcutaneous or transcutaneous monitoring of blood glucose levels in a diabetic patient, as well as contact lens coatings, drug delivery tubing, in situ curable implantible materials such as bioadhesives, nonadhesion coatings for use in surgery, etc.
BACKGROUND OF THE INVENTION
Polymers and polymeric material that include UV absorbers are known in a wide variety of applications. For example, U.S. Pat. No. 5,376,650, to Weaver et al., adentitled “Light Absorbing Polymers”, discloses light-absorbing thermoplastic polymer compositions for imparting color and/or UV protection to thermoplastic resins. U.S. Pat. No. 4,668,739, to Berdahl et al., entitled “Poly(Phenylene Ether)-Bound UV Absorber”, teaches stabilized polyphenylene ether resins incorporating UV absorbers, which are useful as high performance engineering thermoplastics in the production of films, fibers and molded articles. U.S. Pat. No. 5,385,815, to Schofield et al., entitled “Photographic Elements Containing Loaded Ultraviolet Absorbing Polymer Latex,” describes polymers formed from ethylenically unsaturated monomers having pendent UV absorbers, which are useful in protecting silver halides in photographic elements from exposure to UV.
Polyurethanes, polyureas and combined polyurethane/polyureas have been used in the production of biomedical devices, in particular devices, such as glucose sensors, which are implantable in a human patient. For example, U.S. Pat. No. 5,165,407, to Wilson et al., entitled “Implantable Glucose Sensor”, teaches a glucose sensor which is fabricated using a polyurethane coating layer. In certain known manufacturing processes for the production of such sensors, the sensors are produced by sequential buildup of the sensor layers on a substrate. The completed sensors are finally removed from the substrate by use of a laser, which cuts the sensors from the remaining laminate atop the substrate. Known polyurethanes, however, are substantially transparent at the laser wavelengths typically employed (355 nm, in the ultraviolet region of the spectrum), unlike other polymers, such as polyimide (the UV absorption spectrum of which is shown in FIG.
5
), which also form layers of the laminate. This substantial transparency results in processing difficulties.
A need exists for a polymer that is strongly UV absorbent. A need also exists for a polymer, in particular a polyurethane, polyurea or polyurethane/polyurea copolymer, that absorb UV in the same range as other polymers, such as polyimides, that are used in the production of thin film sensors. More specifically, a need exists for a polymer that absorbs UV in the 355 nm range.
A need also exists for a UV-absorbing polymer that is biocompatible, in order to permit use in the production of implantable sensors such as blood glucose sensors.
SUMMARY OF THE PREFERRED EMBODIMENTS
In accordance with one aspect of the present invention, there is provided a UV-absorbing polymer formed from a reaction mixture including a diisocyanate, at least one selected from the group consisting of a diol, a diamine and mixtures thereof, and a polyfunctional UV-absorbing monomer. The inventive polymer is a polyurethane, a polyurea or a polyurethane/polyurea copolymer that strongly absorbs UV, more particularly at 355 nm.
Preferred UV-absorbing monomers which are incorporated in the inventive polymers include biocompatible UV-absorbers, in particular vitamin B
2
and vitamin B
6
.
A plurality of different polyfunctional UV-absorbing monomers, each of which has a different UV absorption range, are used in a preferred embodiment of the inventive polymer.
In a preferred embodiment, the inventive polymers also incorporate a siloxane polymer with terminal functional groups that are reactive with isocyanate.
According to another aspect of the present invention, there is provided a method for producing a polymer as described herein. The method includes the steps of reacting a diisocyanate with a polyfunctional UV-absorbing monomer to form an oligomer, then reacting the oligomer with at least one selected from the group consisting of a diol, a diamine and mixtures thereof.
According to a further aspect of the present invention, there is provided a method for producing a polymer as described herein that includes the steps of reacting a diisocyanate with a polyfunctional UV-absorbing monomer to form a first oligomer, reacting the first oligomer with at least one polyol to form a second oligomer, and reacting the second oligomer with at least one chain extender selected from the group consisting of a diol, a diamine and mixtures thereof.
In still another aspect of the present invention, a method of producing a polymer as described herein includes the steps of reacting a diisocyanate with at least one polyol to form a first oligomer, reacting the first oligomer with a polyfunctional UV-absorbing monomer to form a second oligomer, and reacting the second oligomer with at least one chain extender selected from the group consisting of a diol, a diamine and mixtures thereof.
According to yet another aspect of the present invention, a method of producing a polymer as described herein includes the steps of combining a diisocyanate with a polyflnctional UV-absorbing monomer and at least one polyol to form a reaction mixture, and curing the reaction mixture.
Other objects, features and advantages of the present invention will become apparent to those skilled in the art from the following detailed description. It is to be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the present invention, are given by way of illustration and not limitation. Many changes and modifications within the scope of the present invention may be made without departing from the spirit thereof, and the invention includes all such modifications.


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