Abstract: An improved electrostatographic color printing apparatus includes an exposure unit for forming successive electrostatic latent images on the surface of a recording member in the form of an endless belt, a developing station for sequentially developing the electrostatic latent images to form toner images on the belt, and a transfer zone having electrostatic transfer stations for sequentially transferring the toner images from the belt in superposition onto a receptor sheet fed through the transfer stations while in contact with a belt section therein to produce a multicolour duplex image.

Abstract: An electrostatographic developing device having a developer chamber (26), a toner chamber (21), a dosage reservoir (9) and a developer roller (13) mounted within a rotatable housing (11).

Abstract: An apparatus and method for uniformly contacting an article with a treatment solution. Preferred embodiments are methods of uniformly tinting of contact lenses or uniformly surface modifying contact lenses. The method involves suspending the lens in the treatment solution by application of fluid flow, preferably sinusoidal or pulsed, in a direction opposite the stagnant force (i.e., sum of buoyancy and gravity forces) on the article. The fluid flow prevents the lens from contacting the container structure for periods sufficient to cause non-uniform treatment conditions, while continuously mixing the treatment solution to maintain uniform concentrations throughout.

Abstract: An electrostatic developing device comprising feed passages (54, 58) for a two-component developer, a hopper (43) for adding fresh toner to the developer to maintain its concentration at a desired level, and a mixer with a vertical helical mixer screw (63) rotatable in a stationary housing (42) and a sleeve (65) surrounding the screw in the housing, an annular space (69) being left between the sleeve and the housing allowing developer transported upwardly by the mixer screw within the sleeve to return via the annular space to the lower end of the screw and then become circulated upwardly again.

Abstract: The invention relates to a process for modifying the surface characteristics of a preformed polymer substrate to impart altered properties thereto by graft polymerization on the substrate which includes: placing the polymer substrate in a plasma to form free radicals on the substrate; contacting the substrate having free radicals with oxygen to form hydroperoxy groups on the surface of the substrate; and graft polymerizing an ethylenically unsaturated monomer onto the surface of the polymer substrate.

Abstract: A method of controlling an electrophotographic imaging process wherein a two-component developer is mixed and activated to obtain a uniform distribution and triboelectric charging of the toner, by interruption of the process and carrying out extra activation and mixing cycles as a function of image area coverage and/or distribution of the image over the image field.

Abstract: An apparatus and method for uniformly contacting an article with a treatment solution. Preferred embodiments are methods of uniformly tinting of contact lenses or uniformly surface modifying contact lenses. The method involves suspending the lens in the treatment solution by application of fluid flow, preferably sinusoidal or pulsed, in a direction opposite the stagnant force (i.e., sum of buoyancy and gravity forces) on the article. The fluid flow prevents the lens from contacting the container structure for periods sufficient to cause non-uniform treatment conditions, while continuously mixing the treatment solution to maintain uniform concentrations throughout.

Abstract: A method for making an image using a direct thermal imaging element, comprising on a support a thermosensitive layer incorporating an organic silver salt and a reducing agent contained in said thermosensitive layer and/or in other optional layers, said imaging element being imagewise heated by means of a thermal head having energisable heating elements, characterised in that the activation of the heating elements is executed line by line with a line duty cycle .DELTA. representing the ratio of activation time to total line time, such that the following equation is satisfiedP.ltoreq.P.sub.max 3.3 W/mm.sup.2 +(9.5 W/mm.sup.2 .times..DELTA.)wherein P.sub.max is the maximal value over all heating elements of the time averaged power density P dissipated by a heating element during a line time.

Abstract: A method and composition useful in fabricating radiation-absorbing contact lenses, especially ultraviolet (UV) and visible (tint) light-absorbing lenses. The radiation-absorber is incorporated into a contact lens in the presence of a buffer which maintains the pH near neutral. Subsequently, the radiation-absorber is chemically affixed to the lens by raising the pH to a highly basic level.

Abstract: A method of tinting an unhydrated contact lens involves the steps of providing an unhydrated contact lens; providing a dyestuff solution; providing a printing block comprising a hydrophilic polymer material containing a dye complexing agent capable of noncovalently bonding the dyestuff; placing the dyestuff solution onto the printing block; contacting the unhydrated contact lens and the printing block for a time sufficient to allow the dyestuff solution to diffuse to the lens; and removing the lens from the printing block.

Abstract: A dimensionally stable hydrogel contact lens of polyvinyl alcohol having an equilibrium water content of between about 70 to about 80 weight percent, based upon the total swollen lens weight, said lens having been annealed in a mold essentially conforming to the contact lens dimensions under substantially ambient non-drying setting conditions in the presence of an aqueous-organic annealing promoter solvent, for a period of time substantially sufficient to reach annealing equilibrium.

Abstract: A process for encapsulating a preformed polymeric substrate comprises peroxidizing and hydroperoxidizing the surface of said preformed substrate using ozone and then carrying out a crosslinked graft copolymerization of selected ethylenically unsaturated monomers both on and surrounding (encapsulating) said substrate. Such encapsulation of substrates provides protective coatings, ablative coatings and, particularly, soft skirts for hard contact lenses.

Abstract: A process for modifying the surface characteristics of a preformed polymeric substrate to impart hydrophilicity, hydrophobicity or other desired properties thereto comprises peroxidizing and hydroperoxidizing the surface of said preformed substrate using ozone, directing the subsequent graft polymerization of selected ethylenically unsaturated monomers essentially solely to the surface of said substrate to achieve the desired alteration of substrate surface characteristics while maintaining substrate structural integrity. Substrates so modified are useful in biomedical devices, semipermeable membranes, films, fibers and especially contact lenses.

Abstract: A process for treating hydrophobic polymer surfaces to form hydroxyl moieties thereon comprises ozonating the surface of said hydrophobic polymer to form hydroperoxy groups thereon, and then irradiating said ozonated surface with ultraviolet light or exposing to heat to convert the hydroperoxy groups to hydroxyl moieties in the presence of a hydrogen donor. Such hydroxylated surfaces possess hydrophilic properties and can undergo the chemical reactions characteristic for hydroxyl groups. Polymers so modified are useful in biomedical devices, semipermeable membranes, films, fibers and especially contact lenses.

Abstract: An apparatus for mixing viscous materials has a tank for holding a viscous liquid to be mixed with the upper surface of the liquid at a mixing level in the tank, an impeller rotatably mounted in the tank coaxial with the cylindrical axis of the tank with a plurality of flat lower impeller blades mounted thereon at equally spaced intervals therearound, and inclined to the vertical and at least one plurality of upper blades mounted thereon at equally spaced intervals therearound and substantially midway between the circumferential positions of the lower blades and inclined to the vertical in the same direction as the lower blades and at a greater angle, a drive motor driving the impeller shaft in a direction in which the upper edges of the blades are the leading edges in the direction of rotation, and a plurality of baffles in the tank body at intervals around the inside peripheral surface of the tank between the tank wall and the ends of the blades and having a flat surface on the front side and a surface faci

Abstract: Particulate hydroperoxidized poly-N-vinyl lactam containing an average of about 0.5 to 20 hydroperoxy mole equivalents per mole of poly-N-vinyl lactam, the preparation of the same by subjecting particulate poly-N-vinyl lactam to an effective amount of ozone, and the use thereof in the preparation of graft copolymers possessing a low degree of extractibles, finding utility in a wide number of fields, particularly in biomedical devices, semipermeable membranes, and as films or fibers.

Abstract: Particulate hydroperoxidized poly-N-vinyl lactam containing an average of about 0.5 to 20 hydroperoxy mole equivalents per mole of poly-N-vinyl lactam, the preparation of the same by subjecting particulate poly-N-vinyl lactam to an effective amount of ozone, and the use thereof in the preparation of graft copolymers possessing a low degree of extractibles, finding utility in a wide number of fields, particularly in biomedical devices, semipermeable membranes, and as films or fibers.

Abstract: Particulate hydroperoxidized poly-N-vinyl lactam containing an average of about 0.5 to 20 hydroperoxy mole equivalents per mole of poly-N-vinyl lactam, the preparation of the same by subjecting particulate poly-N-vinyl lactam to an effective amount of ozone, and the use thereof in the preparation of graft copolymers possessing a low degree of extractibles, finding utility in a wide number of fields, particularly in biomedical devices, semipermeable membranes, and as films or fibers.

Abstract: A process for chemically bonding a lubricant to a magnetic disk by applying a functionalized polymeric lubricant to the disk, heating it until a significant portion bonds to the disk via the functional terminal group, and then reacting the unbonded residue with a chemical moiety, the residue then forming a mobile lubricant highly resistant to spin-off due to the presence of the bonded lubricant.

Abstract: A process for modifying the surface of a preformed polymeric substrate to impart lubricity and other desired properties thereto, without at the same time significantly altering the bulk properties of the substrate, by epoxidizing the substrate's surface and reacting the epoxide groups so formed with a fluorocarbon capable of cleaving the epoxide rings and covalently bonding thereto. The article so formed is also disclosed.