Abstract: A method of making a mask or an electronic part, for example a printed circuit, comprises the steps of delivering heat in a desired pattern to a precursor of the mask or electronic part, the precursor comprising a surface coated with a coating, the coating comprising a heat-sensitive composition itself comprising an aqueous developer soluble polymeric substance and a compound which reduces the aqueous developer solubility of the polymeric substance, wherein the aqueous developer solubility of the composition is not increased by incident UV radiation but is increased by the delivery of heat; then developing the precursor to remove the heat-sensitive composition in regions to which the heat was delivered. In the case of a printed circuit precursor the surface may be then etched in conventional manner to yield the required printed circuit.

Abstract: This invention is directed to a precursor for preparing a resist pattern by heat mode imaging, the precursor comprising a heat sensitive composition, the solubility of which in an aqueous alkaline developer is arranged to increase in heated areas, and a means for increasing the resistance of non-heated areas of the heat sensitive composition to dissolution in an aqueous alkaline developer (the “developer resistance means”), wherein said developer resistance means comprises one or more compounds selected from the group consisting of: (A) compounds which include a poly(alkylene oxide) unit; (B) siloxanes; and (C) esters, ethers and amides of polyhydric alcohols, wherein said heat-sensitive composition comprises an aqueous alkaline developer soluble polymeric substance (i.e. the “active polymer”) and a compound which reduces the aqueous alkaline developer solubility of the polymeric substance (i.e.

Abstract: Thermally imageable lithographic printing plate precursors and heat-sensitive compositions for use in these printing plate precursors are disclosed. The compositions contain an aqueous developer soluble polymer, such as a phenolic resin; a compound that reduces the aqueous developer solubility of the polymer; and optionally, and infrared absorber. Examples of compounds that reduce the aqueous developer solubility of the polymer are those that contain at least one quarternized nitrogen atom, such as quinolinium compounds, benzothiazolium compounds, pyridinium compounds, and imidazoline compounds. On thermal imaging, the irradiated areas become more soluble in the aqueous developer and can be removed to form a positive image.

Abstract: Phenolic resin compositions formulated for use in lithographic exposure processes are given a heat treatment at 40-90° C. for at least 4 hours shortly after their coating onto lithographic substrates, to produce lithographic printing forms. It is found that such a heat treatment improves later exposure processes, in particular by rendering the sensitivity of the compositions less variable, over time.

Abstract: A method of making a mask or an electronic part, for example a printed circuit, comprises the steps of delivering heat in a desired pattern to a precursor of the mask or electronic part, the precursor comprising a surface coated with a coating, the coating comprising a heat-sensitive composition itself comprising an aqueous developer soluble polymeric substance and a compound which reduces the aqueous developer solubility of the polymeric substance, wherein the aqueous developer solubility of the composition is not increased by incident UV radiation but is increased by the said delivery of heat; then developing the precursor to remove heat-sensitive composition in regions to which the heat was delivered. In the case of a printed circuit precursor the surface may then be etched in conventional manner to yield the required printed circuit.

Abstract: Thermally imageable lithographic printing plate precursors and heat-sensitive compositions for use in these printing plate precursors are disclosed. The compositions contain an aqueous developer soluble polymer, such as a phenolic resin; a compound that reduces the aqueous developer solubility of the polymer; and optionally, and infrared absorber. Examples of compounds that reduce the aqueous developer solubility of the polymer are those that contain at least one quarternized nitrogen atom, such as quinolinium compounds, benzothiazolium compounds, pyridinium compounds, and imidazoline compounds. On thermal imaging, the irradiated areas become more soluble in the aqueous developer and can be removed to form a positive image.

Abstract: Thermally imageable lithographic printing plate precursors and heat-sensitive compositions for use in these printing plate precursors are disclosed. The compositions contain an aqueous developer soluble polymer, such as a phenolic resin; a compound that reduces the aqueous developer solubility of the polymer; and optionally, and infrared absorber. Examples of compounds that reduce the aqueous developer solubility of the polymer are those that contain at least one quarternized nitrogen atom, such as quinolinium compounds, benzothiazolium compounds, pyridinium compounds, and imidazoline compounds. On thermal imaging, the irradiated areas become more soluble in the aqueous developer and can be removed to form a positive image.

Abstract: A process for the manufacture of a porous diaphragm of a synthetic material, especially polytetrafluoroethylene, which comprises forming a sheet of the synthetic material in admixture with a solid particulate additive (eg starch) to be removed therefrom, introducing said sheet into an electrolytic cell, filling the cell with the working electrolyte and removing the solid particulate in situ in the cell by electrolysing the said electrolyte. The porous diaphragms are especially suitable for use in diaphragm cells for the production of chlorine wherein the working electrolyte is sodium chloride brine.