Optics: eye examining – vision testing and correcting – Spectacles and eyeglasses – Ophthalmic lenses or blanks
Patent
1997-08-18
2000-08-08
Sugarman, Scott J.
Optics: eye examining, vision testing and correcting
Spectacles and eyeglasses
Ophthalmic lenses or blanks
351177, G02C 704
Patent
active
060991224
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a novel coating process that comprises the use of a functional photoinitiator, or a macroinitiator derived therefrom, in a cascade of process steps, wherein, on the one hand, a functional photoinitiator or a macroinitiator derived therefrom is covalently bonded to a carrier and, on the other hand, an oligomer or polymer forming a new surface layer is covalently bonded to the functional photoinitiator, or to the carrier modified by a functional photoinitiator, via functional groups that are co-reactive with isocyanate groups. The invention relates also to novel intermediates that are carriers to which functional photoinitiators that contain free isocyanate groups are bonded.
The surface-modification of polymers has been the focus of interest for many years. The properties of a polymer often have to satisfy various physical and chemical requirements which, because of the material used, can often be met only in part. One possible way of meeting those requirements is to cover a base material with a thin layer of a second material. The latter should supply the properties lacking in the first material but not alter the fundamental properties of the base material. Special attention is paid in this connection to improved bio-compatibility in the widest sense, for example to the wettability of polymer surfaces.
A pioneering work in the field of surface-modification of polymers, aimed at improving specifically the wettability of the surfaces of contact lenses, has come from Yasuda et al., J. Biomed. Mater. Res. 9, 629 (1975). The authors describe a process in which a layer of 20 nm thickness is applied by plasma polymerisation of a mixture of acetylene, water and nitrogen to a PMMA contact lens. The plasma is produced in an apparatus for downstream coating, with a high-frequency glow discharge and an operating frequency of 13.56 MHz. The contact angle of a normal, untreated PMMA surface is, according to the standing water droplet method, approximately 71.degree. and, after the plasma polymerisation coating just described, approximately 37.degree..
Another attractive method for applying thin hydrophilic films to substrates is to use unsaturated alcohols in the plasma polymerisation. Hozumi et al., Pure & Appl. Chem. 60, 697 (1988), describe a high-frequency glow discharge method in which they employ allyl alcohol and propargyl alcohol, and also 2-methyl-3-butyn-2-ol. The tests, carried out mainly with propargyl alcohol, show that a contact angle of 45.degree. results after the coating. If, in addition, water is added to the operating gas in the plasma polymerisation, the contact angle can even be reduced to 20.degree.. When a product so coated is swelled with water, however, it is found that the additional layer exhibits unsatisfactory adhesion to the substrate.
Two more recent publications, PCT-AU 89/00220 and H. J. Griesser, Materials Forum, 14 (1990) 192, deal with a plasma polymerisation method in which organic compounds, such as saturated alcohols, saturated amines, derivatives or mixtures thereof, and inorganic gases, such as oxygen, hydrogen, nitrogen, helium, argon or neon, and water vapour are applied as a plasma polymer to a contact lens. According to the authors, the water content should lie between a maximum of 20% by volume and preferably 5% by volume. The presence of water is intended to prevent excessive crosslinking of the plasma polymer. Examples are given in which films are applied by plasma polymerisation of ethanol and isobutanol. During the glow discharge, the substrates are subjected to an energy of approximately 1 watt/cm.sup.2 between two plane-parallel electrodes. If a sufficiently high static potential occurs on those substrates, spontaneous, high-energy discharges are released which greatly heat the substrate and cause internal stresses. As a result, plasma polymer deposits that are highly crosslinked and difficult to control are produced.
WO 94/06485 describes a multi-layer material, especially a biomedical article and preferabl
REFERENCES:
patent: 5527925 (1996-06-01), Chabrecek et al.
patent: 5532112 (1996-07-01), Koehler et al.
Chabrecek Peter
Lohmann Dieter
Ciba Vision Corporation
Gorman, Jr. Robert J.
Meece R. Scott
Sugarman Scott J.
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