Abstract: Method for producing flexographic printing plates from a photopolymerizable flexographic printing plate with a dimensionally stable support, photopolymerizable, relief-forming layer(s), and a digitally imagable layer. The method comprises (a) producing a mask by imaging the digitally imagable layer, (b) exposing the flexographic printing plate with a plurality of UV-LEDs on a UV-LED strip through the mask with actinic light, and photopolymerizing the image regions of the layer, and (c) developing the photopolymerized layer. In the UV-LED strip or in a separate strip, at least one ultrasonic sensor is arranged for determining the thickness of the flexographic printing plate for exposure. Depending on the measured thickness of the flexographic printing plate, the exposing of the flexographic printing plate is controlled in respect of: (i) number of exposure steps, exposure intensity, energy input per exposure step, duration of the individual exposure steps, and/or overall duration of exposure.

Abstract: The present invention relates to a multi-functional carbamate having a soft segment, which can be used as a raw material in the preparation of a polyisocyanate having a special siloxane soft segment in its structure by a non-phosgene method; to a polyisocyanate having a special siloxane soft segment prepared by a non-phosgene method; to a urethane prepolymer having a special siloxane soft segment, prepared from a polyisocyanate having a special siloxane soft segment and a polyol; and also to a elastomeric urethane having a special siloxane soft segment, prepared by reacting a polyisocyanate having a special siloxane soft segment with a polyol and an optional chain extender. The present invention also relates to a synthesis method for the above-mentioned substances.

Abstract: A preparation of aryl carbamates can be achieved readily by carbonylation of an aromatic polyamine compound with diphenyl carbonate (DPC) using a combination of an organic acid and a tertiary amine as a catalyst. Aryl carbamate can be converted into 4,4?-diphenylmethane diisocyanate (MDI) by heating it at about 200 to about 230° C. in a non-polar solvent containing inhibitor such as benzoyl chloride. In another application, trans-ureation of biscarbamates with an amine or mixed amines is found to be extremely facile in a polar solvent such as dimethyl sulfoxide (DMSO) and tetramethylene sulfone (TMS) in absence of any catalyst to make polyurea polymers of high molecular weights. Thus, efficient green-chemistry processes based on biscarbamates in making isocyanate products as well as urea prepolymers, urea elastomers and urea plastics have been developed in all in excellent yields without using reactive phosgene or 4,4?-diphenylmethane diisocyanate separately in the trans-ureation polymerizations.

Abstract: A preparation of aryl carbamates can be achieved readily by carbonylation of an aromatic polyamine compound with diphenyl carbonate (DPC) using a combination of an organic acid and a tertiary amine as a catalyst. Aryl carbamate can be converted into 4,4?-diphenylmethane diisocyanate (MDI) by heating it at about 200 to about 230° C. in a non-polar solvent containing inhibitor such as benzoyl chloride. In another application, trans-ureation of biscarbamates with an amine or mixed amines is found to be extremely facile in a polar solvent such as dimethyl sulfoxide (DMSO) and tetramethylene sulfone (TMS) in absence of any catalyst to make polyurea polymers of high molecular weights. Thus, efficient green-chemistry processes based on biscarbamates in making isocyanate products as well as urea prepolymers, urea elastomers and urea plastics have been developed in all in excellent yields without using reactive phosgene or 4,4?-diphenylmethane diisocyanate separately in the trans-ureation polymerizations.