Abstract: The invention provides a method of creating a material for use as a material to be coated by curtain coating, comprising the step of: creating a surface texture of said material such that when said material is coated with a freely falling curtain formed of a composite layer of one or more coating compositions that impinges at a point of impingement against a continuously moving receiving surface of said material using roughness assisted wetting, the height of the composite layer at a distance &lgr; from the point of impingement, in which &lgr; is the average periodicity of the surface texture, is less than or equal to Rz. The invention also provides a method of identifying a material suitable for coating with Roughness Assisted coating.

Abstract: An apparatus and method of bead coating a web using a coating die. The method comprises forming one or more layers of coating material using the coating die and allowing the one or more layers to impinge on the web as the web and die move relative to each other. The web surface has an average peak to peak roughness as defined by DIN 4768, ISO4287 or BS1134 between 2 &mgr;m and 20 &mgr;m. The layer of coating material forming a wetting layer adjacent to the web has a viscosity of between 35 mPas and 200 mPas measured at a shear rate of substantially 10,000 s−1. An electrostatic field is provided at the point at which the layers impinge on the web to stabilize the layers of coating material. The method enables the web being coated to be conveyed at a speed greater than 400 cm/s relative to the coating die whilst avoiding the problem of air entrainment.

Abstract: A method is taught for debubbling a liquid composition containing entrained gas bubbles that increases the effectiveness of ultrasonic debubbling apparatus employed. The method comprises the steps of immersing an ultrasonic horn in water, the horn being contained within a vessel and coupled to a pair of transducers; adjusting an RF generator connected to the pair of transducers to produce a signal at or near a parallel resonance frequency of the pair of transducers; fixing the RF generator at a constant voltage level; and flowing the liquid composition to be debubbled through the vessel with the RF generator operating at constant voltage level and at a variable operating power level that varies with the viscosity of the liquid composition.

Abstract: The invention provides a method of creating a material for use as a material to be coated by curtain coating, comprising the step of: creating a surface texture of said material such that when said material is coated with a freely falling curtain formed of a composite layer of one or more coating compositions that impinges at a point of impingement against a continuously moving receiving surface of said material using roughness assisted wetting, the height of the composite layer at a distance &lgr; from the point of impingement, in which &lgr; is the average periodicity of the surface texture, is less than or equal to Rz. The invention also provides a method of identifying a material suitable for coating with Roughness Assisted coating.

Abstract: A method is taught for debubbling a liquid composition containing entrained gas bubbles that increases the effectiveness of ultrasonic debubbling apparatus employed. The method comprises the steps of immersing an ultrasonic horn in water, the horn being contained within a vessel and coupled to a pair of transducers; adjusting an RF generator connected to the pair of transducers to produce a signal at or near a parallel resonance frequency of the pair of transducers; fixing the RF generator at a constant voltage level; and flowing the liquid composition to be debubbled through the vessel with the RF generator operating at constant voltage level and at a variable operating power level that varies with the viscosity of the liquid composition.

Abstract: An apparatus and method of bead coating a web using a coating die. The method comprises forming one or more layers of coating material using the coating die and allowing the one or more layers to impinge on the web as the web and die move relative to each other. The web surface has an average peak to peak roughness as defined by DIN 4768, ISO4287 or BS1134 between 2 &mgr;m and 20 &mgr;m. The layer of coating material forming a wetting layer adjacent to the web has a viscosity of between 35 mPas and 200 mPas measured at a shear rate of substantially 10,000 s−1. An electrostatic field is provided at the point at which the layers impinge on the web to stabilize the layers of coating material. The method enables the web being coated to be conveyed at a speed greater than 400 cm/s relative to the coating die whilst avoiding the problem of air entrainment.

Abstract: The bead and curtain coating methods for coating photographic compositions on smooth receiving surfaces at speeds about 300 ft/min are improved by the addition of a predictive step for the effect of the receiving surface on coating latitude. This step involves measuring the speed for entraining air for coating aqueous compositions from a nozzle applicator such as a capillary tube on the receiving surface and computing an index value predictive of bead and curtain coating performance.