Liquid, radiation-curable composition, especially for producing flexible cured articles by stereolithography

Abstract

The present invention relates to stereolithographic compositions containing an actinic radiation-curable and cationically polymerizable organic substance, a cationic initiator, a radical photoinitiator, and at least one cationic reactive modifier containing at least two reactive groups per molecule or at least one polyether polyol or mixtures thereof. The cationic reactive modifier has at least one chain extension segment with a molecular weight of at least about 100 and not more than about 2,000. The polyether polyol has a molecular weight greater than or equal to about 4,000. The use of the cationically reactive modifiers and polyether polyol modifiers substantially increases the flexibility and toughness of the cured articles without compromising photospeed, accuracy and wetting-recoatability of the compositions. The present invention further relates to a method of producing a cured product, particularly three-dimensional shaped articles by treating the composition described above with actinic radiation.

What is claimed is:  
     
         1 . A liquid, radiation-curable stereolithographic composition comprising: 
 a) from 20 to 90 percent by weight of actinic radiation-curable and cationically polymerizable organic compounds;    b) from 0.05 to 12 percent by weight of a cationic initiator;    c) from 0.5 to 60 percent by weight of at least one cationic reactive modifier containing at least two reactive groups per molecule, or at least one polyether polyol component or mixtures thereof, wherein the cationic reactive modifier has at least one chain extension segment with a molecular weight of at least about 100 and not more than about 2,000, and the polyether polyol component has a molecular weight greater than or equal to about 4,000;    d) 0 to 10 percent by weight of a radical photoinitiator;    e) 0 to 40 percent by weight of a free radically curable component containing at least one mono- or poly(meth)acrylate;    f) 0 to 10 percent by weight of a polyol different from said polyether polyol component; and    g) 0 to 10 percent by weight of customary additives.    
     
     
         2 . A curable composition according to  claim 1  wherein the actinic radiation-curable and cationically polymerizable organic substance comprises 10 to 80% by weight of at least one solid or liquid cycloaliphatic polyepoxide having at least two epoxy groups with epoxy equivalent weight between 70 and 350 g/eq, or mixtures thereof.  
     
     
         3 . A curable composition according to  claim 1  wherein the actinic radiation-curable and cationically polymerizable organic substance comprises 3 to 70% by weight of at least one solid or liquid polyglycidylether of aliphatic, alicyclic or aromatic alcohol or polybasic acid, epoxy cresol novolac, epoxyphenol novolac, spiro-orthoester compounds, oxetane compounds, having at least two cationically reactive groups per molecule, or mixtures thereof.  
     
     
         4 . A curable composition according to  claim 1  wherein the actinic radiation-curable and cationically polymerizable organic substance comprises 0.5 to 40% by weight of at least one solid or liquid vinylether having at least two vinylether groups or at least a hydroxyl-functionalized vinyl ether.  
     
     
         5 . A curable composition according to  claim 1  wherein the composition contains about 3 to 40% by weight of a free radically curable component containing at least one mono- or poly(meth)acrylate.  
     
     
         6 . A curable composition according to  claim 1  wherein the cationic reactive modifier and the polyether polyol modifier are solid or liquid at room temperature.  
     
     
         7 . A curable composition according to  claim 1  wherein the cationic reactive modifier comprises at least one reactive solid or liquid compound containing an aliphatic or aromatic epoxide having at least one glycidylether group or cycloaliphatic epoxy group or vinylether group or spiro-orthoester group or oxetane group.  
     
     
         8 . A curable composition according to  claim 7  wherein the cationic reactive modifier has an equivalent weight per epoxide at least about 180 and not more than about 2000.  
     
     
         9 . A curable composition according to  claim 7  wherein each chain extension segment of the reactive modifier contains independently from one another at least 4 and not more than about 80 repeating units of C 2 -C 4 alkoxy, oxytetramethylene-, ethyl-, propyl-, isopropyl-, saturated or unsaturated C 2 -C 4 carbon atoms, or mixtures thereof.  
     
     
         10 . A curable composition according to  claim 7  wherein the cationic reactive modifier is at least one reactive liquid or solid glycidylether compound of aliphatic or alicyclic or aromatic alcohols or polybasic acids having, on average, at least two epoxy groups per molecule containing a plurality of chain extension segments, wherein each chain extension segment has a molecular weight of at least about 100 and not more than 2000.  
     
     
         11 . A curable composition according to  claim 10  wherein the cationic reactive modifier is a polyglycidyl ether of an aliphatic polyhydric alcohol or adducts or polybasic acid thereof chain extended with ethoxy-, propoxy-, isopropoxy-, oxytetramethylene-, saturated or unsaturated alkyl-, alicyclic-, polyether- and polyester- linkages, or combinations thereof.  
     
     
         12 . A curable composition according to  claim 11  wherein the reactive modifier is a triglycidylether of poly(isopropoxylated) glycerol having the following formula:  
       
         
           
           
               
               
           
         
       
     
     
         13 . A curable composition according to  claim 11  wherein the reactive modifier is a dimer acid diglycidylether ester or polyglycol polyepoxide or polyglycidylether of castor oil having at least two epoxy groups per molecule.  
     
     
         14 . A curable composition according to  claim 13  wherein the reactive modifier is 
 CH 2 (O)CH—CH 2 —O—C(O)—C n —C(O)O—CH 2 —CH(O)CH 2 ,  
 CH 2 (O)—CH—CH 2 —O—[(CH 2 CH(CH 3 )—O] m —CH 2 —CH—CH 2 (O),  
 wherein n is greater than 15 and less than 150 and m is greater than 4 and less than 50.  
 
     
     
         15 . A curable composition according to  claim 14  wherein n is greater than 30 and less than 50 and m is greater than 6 and less than 15.  
     
     
         16 . A curable composition according to  claim 7  wherein the composition comprises from about 1 to about 60 percent by weight of cationic reactive modifier.  
     
     
         17 . A curable composition according to  claim 1  wherein the polyether-polyol component has the following formula: 
       [—O—A—O—R 1 —] m , 
       where m is such that the molecular weight of the polyether polyol is greater than or equal to 4,000, 
 A is para-, meta- or ortho- substituted aromatic diol residue selected from Bisphenol A, Bisphenol F, p, m, o-Biphenyl, p-, m-, o-Hydroquinone, substituted with aliphatic or aromatic substituents having (un)saturated C 1 -C 5 alkylgroups, ether- or ester-groups; para, meta and ortho substituted aromatic structures of the following structure:  
                     
 where R 2  is at least one —O—, —SO 2 —, —CO—, —COO—, —OCH 2 —, —CH 2 —, (CH 3 ) 2 C<, and an aliphatic or aromatic chain extension segment having 1 to 100 repeating C 1 -C 4  units of saturated and/or unsaturated alkyl-, alkoxy-, aryloxy-, ethoxy, propoxy, isopropoxy, oxytetramethylene, aliphatic or aromatic ester, siloxane and carbonate linkages,  
 R 1  is CH 2 CH(OH)(CR 3 R 4 ) n —,  
 where n is greater than or equal to 1,  
 R 3  and R 4  are independently of one another —H, —CH 3 , —CH 2 CH 3 , saturated or unsaturated linear or branched C 1 -C 20 alkylgroups, aliphatic or alicyclic or aromatic segment containing aromatic ether, aliphatic ether, ethoxy, propoxy, isopropoxy, oxytetramethylene, aliphatic or aromatic ester, siloxane and carbonate linkages.  
 
     
     
         18 . A curable composition according to  claim 17  wherein A is a linear or branched aliphatic or substituted alicyclic diol or unsubstituted alicyclic diol residue bearing saturated or unsaturated C 1 -C 20 alkylgroups, ether, ethoxy, propoxy, isopropoxy, oxytetramethylene, ester, sulfone, sulfoxide, siloxane and carbonate linkages.  
     
     
         19 . A curable composition according to  claim 17  wherein A is an aliphatic or substituted alicyclic diol or unsubstituted alicyclic diol, cyclohexane dimethanol, hydrogenated Bisphenol A and hydrogenated Bisphenol F.  
     
     
         20 . A curable composition according to  claim 17  wherein A is an aromatic diol residue selected from Bisphenol A, Bisphenol F, hydroquinone, biphenol, aromatic diols bearing a flexible segment between the aromatic rings and R 1  is —CH 2 CH(OH)CH 2 —.  
     
     
         21 . A curable composition according to  claim 20  wherein A is an aromatic diol residue selected from Bisphenol A, R 1  is —CH 2 CH(OH)CH 2 — and m is greater than 15.  
     
     
         22 . A curable composition according to  claim 21  wherein the composition comprises the reactive polyether polyol modifier from about 1 to about 45 percent by weight.  
     
     
         23 . A curable composition according to  claim 17  wherein the reactive modifier solid or liquid polyether-polyol component is blended, dispersed, diluted or dissolved in at least one liquid or solid diol or polyol containing aromatic rings or polyester linkages or polyether linkages or which is a derivative of aliphatic, alicyclic or aromatic polyhydric alcohols.  
     
     
         24 . A curable composition according to  claim 17  wherein A is an aliphatic polyol and the polyether polyol component is a solid or liquid aliphatic polyether-polyol.  
     
     
         25 . A curable composition according to  claim 1  wherein the cationically curable component is a mixture comprising at least one polyglycidyl compound or cycloaliphatic polyepoxide or aromatic ring-, epoxy cresol novolac or epoxy phenol novolac-containing polyglycidyl compound having, on average, at least two epoxy groups per molecule and at least one vinyl ether-based resin.  
     
     
         26 . A curable composition according to  claim 1  wherein the composition further comprises from 0.5 to 40 percent by weight of a liquid or solid polyhydroxyl compound.  
     
     
         27 . A curable composition according to  claim 26  wherein said polyhydroxyl compound comprise substances having aromatic carbon rings in their molecules or phenolic compounds having at least two hydroxyl groups or phenolic compounds having at least two hydroxyl groups which are reacted with ethylene oxide, propylene oxide or with ethylene oxide and propylene oxide or hydroxyl compounds having at least one hydroxyl group and at least one epoxide group.  
     
     
         28 . A curable composition according to  claim 26  wherein said polyhydroxyl compound contains aliphatic, alicyclic or substituted alicyclic groups.  
     
     
         29 . A curable composition according to  claim 26  wherein said polyhydroxyl compound is a derivative of aliphatic or alycyclic or aromatic polyhydric alcohols bearing polyester, polyether, polysiloxane and/or polyhydrocarbon linkages.  
     
     
         30 . A curable composition according to  claim 1  wherein the at least one polyfunctional (meth)acrylate has, on average, between 2 to 7 acrylate groups.  
     
     
         31 . A method of producing a cured product, in which a composition according to  claim 1  is treated with actinic radiation.  
     
     
         32 . A method for producing three-dimensional shaped articles comprising: 
 a) treating a radiation-curable composition according to  claim 1  with actinic radiation to form an at least partially cured layer on the surface of said imposition within a surface region corresponding to a desired cross-sectional area of the three-dimensional article to be formed,    b) covering the at least partially cured layer produced in step (a) with a new layer of said radiation-curable composition, and    c) repeating steps (a) and (b) until an article having the desired shape is formed, and optionally,    d) post-curing the resulting article.