Imperial Chemical Industries Limited

Ian D Pavey

Timothy J Noakes

Colin M Waters

Raymond C Rowe

Christopher S Jeffs

Chiyoji Hitomi

Stuart C Ord

Douglas Bray

Timothey J Noakes

A coating is applied to a substrate by conveying the substrate past a number of liquid spraying nozzles (32) to which high voltage is applied to produce spray in the form of liquid ligaments which deposit as such, or in the form of droplets, on the substrate to form generally parallel tracks which merge with each other to produce a substantially uniform thickness coating. The nozzles (32) are operable in two modes: a normal spraying mode and a deflect mode in which the ligaments are deflected away from the substrate and towards a collector electrode (34). Operation of the nozzles (32) may be co-ordinated so that different formulations are deposited as separate panels in succession lengthwise of the substrate. The coating system is particularly suitable for coating multicoloured dyesheets for use in thermal transfer printing.

Spraying of liquids

A liquid crystal device comprises a layer of fibers or filaments (15) permeated with liquid crystal material, the layer (15) being located between electrodes (13, 14) by means of which an electric field can be applied across the layer to vary the transmissivity of the liquid crystal/fiber composite. The diameters of the fibers/filaments are selected so that the light transmissivity of the composite has reduced sensitivity with respect to mismatch of the refractive indices of the liquid crystal and the fibers/filaments.

Liquid crystal devices

A method of making a liquid crystal device comprises producing, for example by means of electrostatic spraying, ligaments of a curable liquid which are deposited as such or as droplets (as a result of breaking up of the ligaments) on a sheet which is to form one boundary wall of the device. Curing of the liquid may be initiated while the liquid is in flight and completed after deposition. Liquid crystal material is applied to the deposited ligaments or droplets and a second sheet is laminated with the first sheet to encapsulate the liquid crystal material. The deposited ligaments or droplets serve to space the sheets apart and/or provide surfaces with which, in the field-off condition, the liquid crystal molecules can align in directions different to the direction of alignment induced by application of an electric or magnetic field.

Process for producing liquid crystal devices

Apparatus, for example an inhaler, is disclosed in which a spray is formed electrostatically from an outlet 6 to achieve uniform droplet size. The spray is then discharged for its intended use--in the example inhaling. The spray is discharged completely by corona produced by a sharp discharge electrode 16 which is charged to a polarity opposite that of the liquid. In order to prevent the corona from spoiling the formation of the spray itself, the liquid of the outlet 6 is protected by a neutral shield electrode 8. The spray issues through a hole 14 in the shield electrode. The hole is sufficiently small to prevent corona getting through, yet sufficiently large to allow the spray through.

Apparatus for producing a spray of droplets of a liquid

A process for the production of solid particles, characterized by the solidification in flight of an electrically charged spray of fluid droplets of narrow particle size distribution, and an apparatus for that process comprising a sprayhead with a channel for the fluid communicating with an outlet; means for subjecting the fluid to an electrical field such that the fluid will move from the sprayhead under the influence of the field to produce a spray of the fluid, the means including means for applying a first potential to the fluid; an electrode mounted spaced from but adjacent to the sprayhead with means to apply a second potential to that electrode; and a spray chamber, so positioned that in use the sprayhead delivers the spray to the chamber interior, and provided with means to apply a third potential to the chamber, and so dimensioned and arranged that in use the majority of the spray droplets solidify before impinging on any surface of or within the chamber.

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Sussex, United Kingdom

Ian D Pavey