Abstract: Flexible printing plates are produced from printing plates consisting essentially of a dimensionally stable substrate (1) and a recording layer (2) by a process in which the printing plate is produced alternatively either by photochemical or by mechanical structuring, and in the case of photochemical structuring the photosensitive recording layer (2) is exposed imagewise and the unexposed parts of the recording layer (2) are washed out with a developer and in the case of mechanical structuring the originally photosensitive, uniformly exposed recording layer (2) is cut imagewise and the nonprinting parts of the recording layer (2) are peeled off from the substrate (1).The printing plates produced by this process are suitable for the production of products printed by the flexographic method and for lacquering products printed by the offset method.

Abstract: Flexible printing plates are produced from printing plates consisting essentially of a dimensionally stable substrate (1) and a recording layer (2) by a process in which the printing plate is produced alternatively either by photochemical or by mechanical structuring, and in the case of photochemical structuring the photosensitive recording layer (2) is exposed imagewise and the unexposed parts of the recording layer (2) are washed out with a developer and in the case of mechanical structuring the originally photosensitive, uniformly exposed recording layer (2) is cut imagewise and the nonprinting parts of the recording layer (2) are peeled off from the substrate (1).The printing plates produced by this process are suitable for the production of products printed by the flexographic method and for lacquering products printed by the offset method.

Abstract: A new liquid cleaner composition is provided for the mild and gentle removal of polymeric materials from sufaces without leaving any residues. The said new cleaner composition is an emulsion of the water-in-oil type comprising an aqueous phase finely dispersed in a continuous phase selected from the group consisting of nonflammable, fire-retardant, high-boiling, and fire-retardant and high-boiling organic phases, the volume ratio of the finely dispersed aqueous phase to the continuous organic phase being in the range of from 90:10 to 10:90. The new liquid cleaner composition can contain alcohols, surface-active agents and further useful additives. The new liquid cleaner composition is most preferably used in the process for preparing photopolymerized flexographic relief printing plates as the developer for washing out the non-irradiated and thus non-photopolymerized areas of the imagewise irradiated relief-forming recording layers of the said flexographic relief printing plates.

Abstract: The present invention relates to an improved process for preparing a photopolymerized flexographic relief printing plate or a photoresist from a photosensitive element comprising a photopolymerizable layer consisting essentially of(A) at least one polymer as the binder,(B) at least one photopolymerizable monomer compatible with said binder (A) and(C) one photoinitiator, by(i) imagewise exposing said photopolymerizable layer of said element to actinic light and(ii) washing out the unexposed, non-photopolymerized parts of said layer with a developer, thereby obtaining a photopolymerized flexographic relief printing plate or a photoresist.The improvement of said process comprises: washing out the non-photopolymerized parts of the irradiated photopolymerizable layer with the developer which consists essentially of at least one hydrogenated petroleum fraction having a flashpoint above 45.degree. C. and a boiling range of from 160.degree. to 220.degree. C.

Abstract: A flexographic printing relief-plate, which has a relief layer (P), an interlayer (Z) and a base layer (U), is provided with a double-sided adhesive sheet (W). The double-sided adhesive sheet (W) transmits actinic light and is firmly bonded to the base layer (U) on one side. On the opposing side, the adhesive sheet (W) has an adhesive force of from 1 to 6 N/25 mm. This force is less than the adhesive force on the side bonded to the base layer (U). The adhesive sheet (W) permits the flexographic relief printing plate to be repeatedly adhered to and removed from the printing cylinder without damaging the plate.

Abstract: A method of joining the edges of flexographic printing plates on printing cylinders, which includes the following steps:(i) fixing the printing plates to make-ready cylinders by means of a first double-sided self-adhesive film having the same area as the printing plate,(ii) cutting the printing plates to size so that they fit the printing cylinders,(iii) removing the cut printing plates from the make-ready cylinders and from the first self-adhesive films,(iv) fixing the cut printing plates by means of a second double-sided self-adhesive film, which has the same area as the printing plates and from 1.6 to 2.

Abstract: To transfer a toner image from a toner-treated surface, a toner transfer film is employed, which comprises a transparent base carrying a transparent layer which is capable of picking up toner and has a temporary slight surface tack, the layer consisting of a mixture containing a polymeric and/or pre-polymeric binder, a polymerizable low molecular weight compound and a polymerization initiator. After transfer, the toner image can be permanently fixed to the toner transfer film by heating the film and/or exposing it to light.

Abstract: A printing plate produced by a photochemical process is treated using an apparatus in which one or more flat washout elements are arranged facing the exposed side of the plate passing through the apparatus, these washout elements moving to and fro at right angles to the direction of transport of the plate and being covered with a long-fibered fabric on the side facing the plate.

Abstract: Photopolymerizable compositions for the manufacture of relief printing plates, especially relief plates for making mats, comprising an alcohol-soluble linear polyamide, a photoinitiator and a mixture of (a) a diether or triether obtained from 1 mole of an aliphatic diol or triol and from 2 to 3 moles of N-hydroxymethylacrylamide or N-hydroxymethylmethacrylamide and (b) an unsaturated ester-urethane obtained from 1 mole of toluylene diisocyanate and 2 moles of a hydroxyalkyl acrylate or methacrylate, (a) and (b) being mixed in specific ratios.

Abstract: Fluid photo-crosslinkable composition consisting essentially of a photo-initiator and a mixture ofA. a polyurethane obtained by reacting a hydroxyl-containing saturated aliphatic polyester with a polyisocyanate and a monoacrylate or monomethacrylate of a diol, andB. an N-vinyl lactam optionally in admixture with other monomers.These compositions are suitable for the production of high-quality relief printing plates and have a short processing time.

Abstract: The invention relates to relief plates for flexographic printing comprising a relatively soft elastomeric base (U) having a modulus of elasticity of from 10 to 200 kg/cm.sup.2 and a thickness of from 0.5 to 6 mm and, firmly bonded thereto, a thin, relatively hard, difficultly soluble intermediate layer Z having a modulus of elasticity of from 1 .times. 10.sup.3 to 2.1 .times. 10.sup.6 kg/cm.sup.2 and a thickness of from 5 to 500 .mu. and, firmly bonded to said intermediate layer Z, a relief layer P' consisting of a photocrosslinked elastomeric mixture having a modulus of elasticity of from 30 to 2000 kg/cm.sup.2 and a thickness of from 200 to 300 .mu., the modulus of elasticity of the photocrosslinked relief layer P' being the same as or higher than that of the base U and the neutral surface of the relief plate lying in or near the intermediate layer Z. The invention also relates to photosensitive laminates for the production of such plates.

Abstract: Laminates for the production of relief plates for flexographic printing, by imagewise exposure and washing out with a developer solution have, on a base optionally provided with an elastomeric layer, a photo-crosslinkable layer containing a photoinitiator and consisting of a polyurethane elastomer which has been prepared in a special manner from an aliphatic saturated polyesterglycol, an aliphatic diisocyanate, but-1-ene-3,4-diol and, if desired, another diol and which has a Shore A hardness of 30 to 90.degree. in the photo-crosslinked state, the elastomer being optionally mixed with a photo-crosslinked monomer.