Abstract: Spacers 26 each of which has a concave surface 27 complementary to the spherical surface of a ball 25 at each end thereof are disposed at areas between the adjacent balls 25, 25. A ball circulation mechanism comprises; a through hole 15 which extends in parallel to an axial line 4 of the ball nut 12 inside a thick wall part 14 of the ball nut 12; and adapters 23, 24 having open ends 23a, 24a provided with tongue portions 23c, 24c for scooping up or returning balls 25 between a ball screw groove 11 of a ball shaft 10 and a ball screw groove 13 of the ball nut 12, and the other open ends 23b, 24b being connected to be in communication with the through hole 15, and each adapter being fitted into recesses 16, 17 provided on both axial ends in the thick wall part 14 of the ball nut 12. Therefore, there is no need of upsizing a ball screw, and thus a compact ball screw which has a high load-carrying capacity and is suitable for a reciprocating movement can be provided.

Abstract: A developer composition for presensitized plates for use in making lithographic printing plates comprises water, an alkali silicate and at least one compound having at least one aryl group, at least one oxyalkylene group and at least one sulfate ester group or sulfonic acid group. The composition is excellent in developing stability and processability. It is less foamable and seldom generates deposits even when it is deteriorated. Moreover, the composition makes it possible to develop both positive- and negative-working PS plates.

Abstract: A developer composition comprises an aqueous alkaline solution which contains at least one alkali-soluble mercapto compound and/or thioether compound. The developer composition is excellent in developing properties and provides lithographic printing plates which do not cause background contamination of non-image areas during printing, when it is used in developing PS plates. It can be stored for a long time. The developer composition further makes it possible to develop both negative and positive working PS plates if its pH value is not less than 12.

Abstract: A developer composition which comprises an aromatic compound having hydroxyl groups at the 1- and 3-positions thereof and free of any electron attractive group or a salt thereof, an alkaline agent and water. The developer composition can effectively be used, as a developer, in a method for making lithographic printing plates which comprises the steps of: exposing, to light, a presensitized plate for use in making a lithographic printing plate provided with a water-insoluble image-forming layer formed on a substrate and developing the plate to remove non-image portions. Lithographic printing plates manufactured according to the method provide printed matter free of background contamination. If the pH value of the developer is controlled to not less than 12, both positive-working and negative-working presensitized plate can be treated therewith.

Abstract: A process is described for producing a presensitized lithographic printing plate by coating onto a surface-roughened aluminum plate a solution having dissolved in a solvent containing at least 10 wt % 1-methoxy-2-propanol a negative-working, light-sensitive composition which contains a light-sensitive diazo resin and a high-molecular weight compound and which is developable with an aqueous alkali developer, and drying the coated solution.

Abstract: Light-sensitive compositions comprise a light-sensitive diazo resin, a binder and a compound having a pivaloyl group. Lithographic printing plates prepared by using the light-sensitive compositions of the invention are excellent in ink receptivity.

Abstract: A light-sensitive composition which contains a polyurethane resin having a carbon-carbon unsaturated bond and a carboxyl group. A presensitized plate using the above light-sensitive composition can be developed with an aqueous alkaline developing solution and provides a lithographic printing plate having excellent printing durability.

Abstract: A light-sensitive composition for use with lithographic printing plates is described which comprises (1) a light-sensitive, organic solvent soluble and substantially water-insoluble diazo resin which is the reaction product of a water-soluble, light-sensitive condensate of an aromatic diazonium compound and an organic condensing agent with a halogenated Lewis acid or a salt thereof, (2) a substantially water-insoluble, film forming organic high-molecular weight compound having an acid value of from 10 to 200, (3) a polynuclear aromatic sulfonic acid or a salt thereof, and (4) a salt-forming organic dye compound.

Abstract: A presensitized lithographic printing plate precursor is described, comprising an aluminum support that has been rendered hydrophilic having provided thereon a light-sensitive layer composed of a light-sensitive composition comprising (1) an organic solvent-soluble and substantially water-insoluble diazo resin, (2) a substantially water-insoluble, film-forming polymeric compound, and at least one of (3a) an organic solvent-soluble polymeric compound having a sulfonic acid group or a sulfonic acid salt group in its side chain and (3b) a substituted or unsubstituted dipicolinic acid or a salt thereof, the total amount of (3a) and (3b) components being about 1 to about 100% by weight, based on the weight of the diazo resin.

Abstract: A presensitized printing plate which has a photopolymerizing composition layer provided on at least one side of a support, with the photopolymerizing composition being constituted with (A) a polymer containing in its side chains groups represented by the following general formula (I) and carboxylic groups: ##STR1## (wherein R.sub.1 to R.sub.5 each represents a hydrogen atom, a halogeno group, a carboxyl group, a sulfo group, a nitro group, a cyano group, and amido group, an amino group, or an unsubstituted or a substituted alkyl, aryl, alkoxy, aryloxy, alkylamino, arylamino, alkylsulfonyl or arylsulfonyl group; and Z represents an oxygen atom, a sulfur atom, --NH-- or --NR-- (R=alkyl)), (B) a monomer or an olygomer having at least two polymerizable ethylenically unsaturated double bonds, and (C) a photopolymerization initiator.

Abstract: A heat developable photosensitive material having two or more layers superimposed on a support and containing at least (a) an organic silver salt, (b) a photocatalyst and (c) a reducing agent in one or more such layers, at least one said layers containing (d) a polymer having a repeating unit of the formula: ##STR1## wherein R is a hydrogen atom or a lower alkyl group; and X is a hydrogen atom, or one to three groups selected from the group consisting of a halogen atom, a nitro group, a cyano group, an alkyl group, an alkoxy group, an alkoxycarbonyl group, an alkylsulfonyl group, an aryloxy group, an acyl group, an acyloxy group and an acylamido group.

Abstract: A stabilized photosensitive composition comprising a leuco dye, a photooxidizing agent, and further a 2,4-dihydroxybenzaldoxime which is suitable for use in lithography, photoresists, etc., for obtaining visible contrast between the exposed and unexposed areas.

Abstract: A light-sensitive resin composition containing (a) at least one ethylenically unsaturated compound having at least two terminal ethylenically unsaturated groups, which is capable of forming a polymer through photo-addition polymerization, and which has a boiling point of about 100.degree. C. or higher at atmospheric pressure, (b) an addition polymerization initiator activatable by irradiation with actinic radiation, and (c) an organic high polymer binder having water-solubilizing groups in the side chains thereof, wherein the improvement comprises the binder being a copolymer containing (A) a repeating unit derived from at least one compound selected from the group consisting of acrylic acid and methacrylic acid and (B) a repeating unit derived from at least one compound selected from the group consisting of benzyl acrylate, benzyl methacrylate, phenethyl acrylate, phenethyl methacrylate, 3-phenylpropyl acrylate, 3-phenylpropyl methacrylate, 4-phenylbutyl acrylate and 4-phenylbutyl methacrylate.

Abstract: A photosensitive lithographic printing plate comprising a support having thereon a photosensitive layer composed of a photosensitive diazo-oxide resin containing a hydroxystyrene unit and a hydroxystyrene unit having an o-quinoediazide group bonded through the oxygen of the hydroxystyrene. The photosensitive layer can contain an alkali-soluble resin. The photosensitive lithographic printing plate is stable mechanically, provides a large difference in solubility between the exposed areas and the unexposed areas of the layer, and has improved printability and sensitivity.

Abstract: A light-sensitive lithographic printing plate comprising a support with a hydrophilic surface having thereon a light-sensitive layer comprising a light-sensitive polyester containing o-quinonediazido groups as terminal groups.