Abstract: A power take off coupling for connecting an engine (20, 21) to a site accessory (16, 14, 17), comprises a resilient power transmission component (3) within the coupling; a latching device (8, 46, 9) to mechanically latch the accessory to the engine (20, 21), with a manually operable release handle (13) to effect unlatching. A power output shaft of the engine (20, 21) carries one half (5) of a dog clutch with the other half (7) carried by the accessory (16, 14, 17).

Abstract: A power take off coupling for connecting an engine (20, 21) to a site accessory (16, 14, 17), comprises a resilient power transmission component (3) within the coupling; a latching device (8, 46, 9) to mechanically latch the accessory to the engine (20, 21), with a manually operable release handle (13) to effect unlatching. A power output shaft of the engine (20, 21) carries one half (5) of a dog clutch with the other half (7) carried by the accessory (16, 14, 17).

Abstract: A radiation sensitive material comprises particles including a water-insoluble heat-softenable core surrounded by a shell which is soluble or swellable in aqueous medium. The material also includes a radiation sensitive component which, on exposure to radiation, causes the solubility characteristics of the material to change. The material may be positive- or negative-working and may be coated onto a substrate from aqueous media to form a radiation sensitive plate which, after image-wise exposure, can be developed in aqueous media and then heated to cause the particles to coalesce and form a durable printing image.

Abstract: A radiation sensitive material comprises particles including a water-insoluble heat-softenable core surrounded by a shell which is soluble or swellable in aqueous medium. The material also includes a radiation sensitive component which, on exposure to radiation, causes the solubility characteristics of the material to change. The material may be positive- or negative-working and may be coated onto a substrate from aqueous media to form a radiation sensitive plate which, after image-wise exposure, can be developed in aqueous media and then heated to cause the particles to coalesce and form a durable printing image.

Abstract: A radiation-sensitive plate comprises a substrate coated with a radiation-sensitive composition including a component having groups imparting solubility in aqueous solutions and a component having functional groups capable of reacting with a silane compound. The surface of the composition is modified by reaction with a silane compound. The plate gives rise to images of improved ink receptivity and can be developed in aqueous developer liquids after image-wise exposure.

Abstract: Polyunsaturated diazonium compounds suitable for use in negative working radiation sensitive compositions are provided. They may be produced by reacting an aromatic diazonium compound of the formula(A.sup.- N.sub.2.sup.+).sub.p --Ar--(R).sub.q --(XH).sub.rwith a polyethylenically unsaturated monoisocyanate compound of the general formula ##STR1## where p and q are integers ranging from 1 to 5, r is an integer ranging from 1 to 10; Ar represents a substituted or unsubstituted divalent or polyvalent radical derived from an aromatic or heteroaromatic compound; X represents O, S or a secondary or tertiary amino group; R represents a single bond or a substituted or unsubstituted divalent or other polyvalent radical and may be the same or different when q is greater than 1; A.sup.- represents an anion; Z represents the residue of a polyisocyanate OCN--Z--(NCO).sub.

Abstract: A radiation-sensitive compound has the general formula ##STR1## wherein A represents the ring members required to complete a 5- or 6-membered heterocyclic ring which may optionally be fused to an optionally substituted aromatic nucleus,B represents H, acryl, aroyl, heterocyclyl carbonyl or ##STR2## R represents an optionally substituted alkyl group, E and G, which may be the same or different, each represents H or CH.sub.p X.sub.3-p,J and K, which may be the same or different, each represents an aryl or heterocyclic group, which may optionally include a substitutent additional to E or G,X represents Cl or Br, andm, n and p, which may be the same or different, each represents an integer equal to 0, 1 or 2.The compound can be used to form radiation sensitive compositions for the production of radiation sensitive plates in lithographic printing plate manufacture.

Abstract: Polyunsaturated diazonium compounds suitable for use in negative working radiation sensitive compositions are provided. They may be produced by reacting an aromatic diazonium compound of the formula(A.sup.- N.sub.2.sup.+)p--Ar--(R)q--(XH)rwith a polyethlenically unsaturated monoisocyanate compound of the general formula ##STR1## where p and q are integers ranging from 1 to 5, r is an integer ranging from 1 to 10; Ar represents a substituted or unsubstituted divaient or polyvalent radical derived from an aromatic or heteroaromatic compound; X represents O, S or a secondary or tertiary amino group; R represents a single bond or a substituted or unsubstituted divalent or other polyvalent radical and may be the same or different when q is greater than 1; A.sup.- represents an anion; Z represents the residue of a polyisocyanate OCN--Z--(NCO)n where n is 1 or 2; and Y is the residue of a monohydroxy compound of the formula YOH where Y contains at least two ethylenically unsaturated double bonds.

Abstract: A radiation sensitive plate comprises a substrate coated with a photopolymerisable composition. The composition comprises a polymerisable compound containing ethylenic unsaturation, a perester photoinitiator and optionally an optical sensitiser. The substrate may be a sheet of grained and anodised aluminum and the plate is useful in the production of lithographic printing plates.

Abstract: A polymeric compound is derived from a polyhydric material and has pendant sulphonate groups of the general formula ##STR1## where X is an aliphatic, aromatic, carbocylic or heterocyclic group; Y is hydrogen, halogen or an alkyl, aryl, alkoxy, aryloxy or aralkyl group, CO.sub. --Z.sup.+, CO.sub.2 R or SO.sub.3 -Z.sup.+ ; Z.sup.+ is a cationic counter ion and R is hydrogen, alkyl, alkylene, aryl or aralkyl group.

Abstract: A radiation sensitive composition comprises a radiation sensitive material and a dye which dye undergoes a colour change in the radiation-struck areas on image-wise exposure of the composition and a colour change when the exposed and developed composition is heated to a temperature of at least 180.degree. C.

Abstract: A radiation-sensitive compound has the general formula ##STR1## wherein A represents the ring members required to complete a 5- or 6-membered heterocyclic ring which may optionally be fused to an optionally substituted aromatic nucleus,B represents H, acyl, aroyl, heterocyclyl carbonyl or ##STR2## R represents an optionally substituted alkyl group, E and G, which may be the same or different, each represents H or CH.sub.p X.sub.3-p,J and K, which may be the same or different, each represents an aryl or heterocyclic group, which may optionally include a substituent additional to E or G,X represents Cl or Br, and m,n and p, which may be the same or different, each represents an integer equal to 0, 1 or 2.The compound can be used to form radiation sensitive compositions for the production of radiation sensitive plates in lithographic printing plate manufacture.

Abstract: A radiation sensitive plate comprises a substrate coated with a photopolymerizable composition. The composition comprises a polymerizable compound containing ethylenic unsaturation, a perester photoinitiator and optionally an optical sensitiser. The substrate may be a sheet of grained and anodized aluminum and the plate is useful in the production of lithographic printing plates.

Abstract: A radiation sensitive composition comprises a radiation sensitive material and a dye which dye undergoes a color change in the radiation-struck areas on image-wise exposure of the composition and a color change when the exposed and developed composition is heated to a temperature of at least 180.degree. C.

Abstract: A polymeric compound is derived from a polyhydric material and has pendant sulphonate groups of the general formula ##STR1## where X is an aliphatic, aromatic, carbocylic or heterocyclic group; Y is hydrogen, halogen or an alkyl, aryl, alkoxy, aryloxy or aralkyl group, CO.sub.2 --Z.sup.+, CO.sub.2 R or SO.sub.3 --Z.sup.+ ; Z.sup.+ is a cationic counter ion and R is hydrogen, alkyl, alkylene, aryl or aralkyl group.Wherein the polymeric acompound is produced by reacting a polymer having a plurality of pendant hydroxyl groups with a sulphonato substituted acid or with an ester forming derivative.

Abstract: A printing plate precursor comprises a substrate coated with a radiation sensitive composition comprising a photoinitiator and a photopolymerizable urethane acrylate or methacrylate. The urethane acrylate or methacrylate is produced by partial acrylation or methacrylation of a tetrafunctional polyol and the remaining hydroxy groups of the polyol are reacted with a di or polyisocyanate.

Abstract: Perester compounds suitable for causing the polymerisation of addition polymerisable compounds on exposure to radiation have the general formulae ##STR1##

Abstract: A printing plate precursor comprises a substrate coated with a radiation sensitive composition overcoated with a barrier layer to prevent oxygen inhibiting photopolymerization of the composition. The barrier layer comprises a polymer and an amphoteric compound.