Abstract: There are provided liquid radiation-curable compositions useful for the production of three-dimensional solid articles in solid freeform fabrication systems. The compositions include a cationically polymerizing alicyclic epoxide having at least two epoxy groups, at least one cationic photoinitiator; at least one free radical photoinitiator; and at least one dendritic polymer having either at least six hydroxyl functional groups or at least six (meth)acrylate functional groups.

Abstract: A liquid radiation-curable composition that comprises (A) at least one cationically polymerizing organic substance; (B) at least one free-radical polymerizing organic substance; (C) at least one cationic polymerization initiator; (D) at least one free-radical polymerization initiator; (E) at least one hydroxyl-functional compound; and (F) at least one hydroxyl-functional oxetane compound;

Abstract: A process for forming a three-dimensional article by stereolithography, said process comprising the steps: 1) coating a thin layer of a liquid radiation-curable composition onto a surface said composition including at least one filler comprising silica-type nano-particles suspended in the radiation-curable composition; 2) exposing said thin layer imagewise to actinic radiation to form an imaged cross-section, wherein the radiation is of sufficient intensity to cause substantial curing of the thin layer in the exposed areas; 3) coating a thin layer of the composition onto the previously exposed imaged cross-section; 4) exposing said thin layer from step (3) imagewise to actinic radiation to form an additional imaged cross-section, wherein the radiation is of sufficient intensity to cause substantial curing of the thin layer in the exposed areas and to cause adhesion to the previously exposed imaged cross-section; 5) repeating steps (3) and (4) a sufficient number of times in order to build up the three-dimensi

Abstract: A liquid radiation-curable composition that comprises (A) at least one polymerizing organic substance comprising a mixture of (1) at least one alicyclic epoxide having at least two epoxy groups; and (2) at least one difunctional or higher functional glycidylether of a polyhydric compound; (B) at least one free-radical polymerizing organic substance comprising a mixture of (1) optionally, at least one trifunctional or higher functional (meth)acrylate compound; and (2) at least one aromatic di(meth)acrylate compound; (C) at least one cationic polymerization initiator; (D) at least one free-radical polymerization initiator; (E) optionally, at least one hydroxyl-functional aliphatic compound; and (F) at least one hydroxyl-functional aromatic compound; wherein the concentration of hydroxyl groups in the radiation-curable composition is at least about 1.1 equivalent OH groups per kilogram; wherein the concentration of epoxy groups in the radiation-curable composition is at least about 5.

Abstract: A process for forming a three-dimensional article by stereolithography, said process comprising the steps: 1) coating a thin layer of a liquid radiation-curable composition onto a surface said composition including at least one filler comprising silica-type nano-particles suspended in the radiation-curable composition: 2) exposing said thin layer imagewise to actinic radiation to form an imaged cross-section, wherein the radiation is of sufficient intensity to cause substantial curing of the thin layer in the exposed areas; 3) coating a thin layer of the composition onto the previously exposed imaged cross-section; 4) exposing said thin layer from step (3) imagewise to actinic radiation to form an additional imaged cross-section, wherein the radiation is of sufficient intensity to cause substantial curing of the thin layer in the exposed areas and to cause adhesion to the previously exposed imaged cross-section; 5) repeating steps (3) and (4) a sufficient number of times in order to build up the three-dimensi

Abstract: A liquid colored radiation-curable composition that comprises:

Abstract: A photosensitive composition of (a) a compound of formula (Ia) or (Ib) and (b) a bifunctional acrylate or methacrylate.

Abstract: A liquid radiation-curable composition that comprises

Abstract: A liquid radiation-curable composition that comprises

Abstract: The invention relates to novel crosslinkable prepolymers comprising structural units of the formula wherein the variables are as defined in the claims, to crosslinked polymers, to either homo-polymers or copolymers prepared from those novel prepolymers, to mouldings produced from the said homo- or co-polymers, and especially to contact lenses produced from those homo- or co-polymers.

Abstract: Compounds of formulae (Ia) and (Ib) 1

Abstract: Compounds of formulae (Ia) and (Ib) wherein the substituents R1 are each independently of the other hydrogen or methyl, R2 is an unsubstituted C1-C20alkyl group or a C1-C20alkyl group which is substituted by one or more than one substituent selected from the group consisting of hydroxy, C6-C14aryl and halogen, an unsubstituted phenyl group or a phenyl group which is substituted by one or more than one substituent selected from the group consisting of C1-C6alkyl, hydroxy or halogen, or is a radical of formula —CH2—OR3, wherein R3 is an unsubstituted C1-C20alkyl group or a C1-C20alkyl group which is substituted by one or more than one substituent selected from the group consisting of hydroxy, C6-C14aryl and halogen, an unsubstituted phenyl group or a phenyl group which is substituted by one or more than one substituent selected from the group consisting of C1-C6alkyl, hydroxy and halogen, or is a C2-C6alkenyl group, a C2-C20acyl group or an unsubstituted cyclohexylcarbonyl group or

Abstract: The invention relates to ophthalmic mouldings, especially contact lenses, obtainable by cross-linking a prepolymer that corresponds essentially to formula (1) wherein the variables are as defined in the claims, in the absence or presence of an additional vinyl comonomer.

Abstract: A novel process for producing mouldings, especially contact lenses, is described, comprising the following steps: a) introducing into a mould a prepolymer containing photo crosslinkable groups that is liquid at room temperature or is readily meltable and is substantially free of solvents; b) initiating the photo cross-linking for a period of <20 minutes; c) opening the mould, so that the moulding can be removed for the mould. In accordance with the process according to the invention, it is possible especially to produce contact lenses having valuable properties.

Abstract: The invention relates to moulded ophthalmic articles, especially contact lenses, which are obtainable by cross-linking a prepolymer which is the copolymerization product of (a) at least one polyalkylene glycol of the formula (1): HO--(CH.sub.2 --CH.sub.2 --O).sub.n --(CHY.sub.1 --CHY.sub.2 --O).sub.m --(CHY.sub.3 --CHY.sub.4 --O).sub.p --H or (1'): HO--[(CH.sub.2 --CH.sub.2 --CH.sub.2 --CH.sub.2 --O--)].sub.q --H, (b) at least one polyhydroxy compound selected from the group consisting of (I) a linear or branched aliphatic polyhydroxy compound of the formula (2): R.sub.1 --(OH--).sub.x or a polyether polyol or polyester polyol derived therefrom, and (ii) a cycloaliphatic polyol selected from the group polyhydroxy-C.sub.5 -C.sub.8 -cycloalkane and unsubstituted mono- or disaccharide, (c) at least one di- or polyisocyanate of the formula (3): R.sub.2 --(NCO).sub.

Abstract: Compounds of formulae (Ia) and (Ib) ##STR1## wherein the substituents R.sub.1 are each independently of the other hydrogen or methyl, R.sub.2 is an unsubstituted C.sub.1 -C.sub.20 alkyl group or a C.sub.1 -C.sub.20 alkyl group which is substituted by one or more than one substituent selected from the group consisting of hydroxy, C.sub.6 -C.sub.14 aryl and halogen, an unsubstituted phenyl group or a phenyl group which is substituted by one or more than one substituent selected from the group consisting of C.sub.1 -C.sub.6 alkyl, hydroxy or halogen, or is a radical of formula --CH.sub.2 --OR.sub.3, wherein R.sub.3 is an unsubstituted C.sub.1 -C.sub.20 alkyl group or a C.sub.1 -C.sub.20 alkyl group which is substituted by one or more than one substituent selected from the group consisting of hydroxy, C.sub.6 -C.sub.14 aryl and halogen, an unsubstituted phenyl group or a phenyl group which is substituted by one or more than one substituent selected from the group consisting of C.sub.1 -C.sub.

Abstract: The present invention relates to a process for the stereolithographic preparation of a three-dimensional object, wherein the object is built in a container which contains a radiation-curable liquid formulation with fillers by a repeated alternating succession of process steps (a) and (b). In step (a), a layer of the radiation-curable liquid formulation, one limitation of which is the surface of the formulation, is cured using suitable radiation within an surface area which corresponds to the desired cross-section of the three-dimensional object to be formed at the level of this layer. In step (b), said cured layer is coated with a new layer of the radiation-curable liquid formulation. The process comprises homogenizing the radiation-curable liquid formulation continuously or discontinuously to such an extent that there is no noticeable change in the filler content of the radiation-curable liquid formulation in the area of that layer with which the cured layer is coated in step (b).

Abstract: A liquid, radiation-curable composition which in addition to a liquid, free-radically polymerizable component comprises at least the following additional components: (A) from 40 to 80 percent by weight of a liquid difunctional or more highly functional epoxy resin or of a liquid mixture consisting of difunctional or more highly functional epoxy resins; (B) from 0.1 to 10 percent by weight of a cationic photoinitiator or of a mixture of cationic photoinitiators; and (C) from 0.

Abstract: The invention relates to compounds having at least one vinyl ether group which also contain in the molecule at least one further functional group selected from acrylate, methacrylate, epoxy, alkenyl, cycloalkenyl and vinylaryl groups, to compositions, especially for stereolithography, comprising those vinyl ether compounds, and to a method of producing three-dimensional objects using those compositions.

Abstract: The invention relates to a process for stabilizing a liquid radiation-curable composition comprising a cationically polymerizable compound and a photoinitiator for cationic polymerization against premature commencement of the polymerization, in which a basic ion exchanger is brought into contact with the composition, at least for a certain time. The ion exchanger is preferably removed before commencement of the radiation curing, at least from the part of the radiation-sensitive composition which comes into contact with the radiation. The process is particularly suitable for stabilizing stereolithography baths in extended use against an undesired increase in viscosity.