Solid imaging compositions for preparing polypropylene-like articles

Abstract

This invention discloses compositions adapted to produce, through solid imaging means, excellent quality objects having material properties that simulate the look and feel of polypropylene articles. The objects show the following properties: a tensile modulus in the range of 1000 to 2000 N/mm 2 , an average elongation at break of at least 10% and a yield stress of 24 to 40 kN/mm 2 .

1 . A photosensitive composition suitable for rapid prototyping having the following properties after exposure to actinic radiation: 
 (i) a tensile modulus in the range of 1000 to 2000 N/mm 2 ;    (ii) an average elongation at break of at least 10%; and    (iii) a yield stress of 24 to 40 kN/mm 2 .    
     
     
         2 . The photosensitive composition according to  claim 1  having the property after exposure to actinic radiation that the tensile elongation at yield is at least 7% or no yield is observed at all.  
     
     
         3 . The photosensitive composition according to claims  1  or  2 , wherein the composition comprises the components: 
 (a) 30-70% by weight of an epoxide-containing material;  
 (b) 5-35% by weight of an acrylic material;  
 (c) 0-40% by weight of an hydroxyl-containing material;  
 (d) at least one cationic photoinitiator; and  
 (e) at least one free-radical photoinitiator.  
 
     
     
         4 . The photosensitive composition according to anyone of claims  1 - 3 , wherein the composition contains (a) 35-69.9% by weight of an epoxide-containing material.  
     
     
         5 . The photosensitive composition according to anyone of claims  1 - 4 , wherein the composition contains aromatic acrylic material, cycloaliphatic acrylic material, or combinations thereof.  
     
     
         6 . The photosensitive composition according to anyone of claims  1 - 5 , wherein the composition comprises 10-39% by weight of an hydroxyl-containing material.  
     
     
         7 . The photosensitive composition according to anyone of claims  3 - 6 , wherein the epoxide-containing material is selected from bis(2,3-epoxycyclopentyl)ether, 2,3-epoxy cyclopentyl glycidyl ether, 1,2-bis(2,3-epoxycyclopentyloxy)ethane, bis(4-hydroxycyclohexyl)methane diglycidyl ether, 2,2-bis(4-hydroxycyclohexyl)propane diglycidyl ether, diglycidyl ether of neopentyl glycol, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexane, 3,4-epoxy-6-methylcyclohexylmethyl-3,4-epoxy-6-methylcyclohexanecaboxylate, di(3,4-epoxycyclohexylmethyl)hexanedioate, di(3,4-epoxy-6-methylcyclohexylmethyl)hexanedioate, ethylenebis(3,4-epoxycyclohexanecarboxylate), ethanedioldi(3,4-epoxycyclohexylmethyl)ether, vinylcyclohexene dioxide, dicyclopentadiene diepoxide, 1,2-epoxytetradecane, a di(oxiranyl) poly(oxy-1,4-butanediyl), a partially acrylated bisphenol A epoxy, and 2-(3,4-epoxycyclohexyl-5,5-spiro-3,4-epoxy)cyclohexane-1,3-dioxane, and combinations thereof.  
     
     
         8 . The photosensitive composition according to anyone of claims  3 - 7 , wherein the acrylic material is selected from 1,4-dihydroxymethylcyclohexane diacrylate, bisphenol A diacrylate, trimethylolpropane triacrylate, and ethoxylated bisphenol A diacrylate and combinations thereof.  
     
     
         9 . The photosensitive composition according to anyone of claim  3 - 8 , wherein the hydroxyl-containing material is selected from 1,4-cyclohexanedimethanol, aliphatic and cycloaliphatic mono hydroxy alkanols, an aliphatic polycarbonate diol, and linear and branched polytetrahydrofuran polyether polyols, and combinations thereof.  
     
     
         10 . The photosensitive composition according to anyone of claims  3 - 9 , wherein the free-radical photoinitiator is a 1-hydroxyphenyl ketone.  
     
     
         11 . The photosensitive composition according to anyone of claims  3 - 10 , wherein the free-radical photoinitiator is selected from an alpha-hydroxyphenyl ketone, benzil dimethyl ketal or 2,4,6-trimethylbenzoyldiphenylphosphine oxide.  
     
     
         12 . A three-dimensional article formed from the photosensitive compositions as defined in anyone of claims  1 - 11 , wherein the article has: 
 (i) a tensile modulus in the range of 1000 to 2000 N/mm 2 ;    (ii) an average elongation at break of at least 10%; or    (iii) a yield stress of 24 to 40 kN/mm2.    
     
     
         13 . The three-dimensional article according to  claim 12 , wherein the article has: 
 (i) a tensile modulus in the range of 1000 to 1600 N/mm 2 ;    (ii) an average elongation at break of at least 10%;    (iii) a yield stress of 28 to 40 kN/mm2 and    (iv) a tensile elongation at yield of at least 7% or no yield.    
     
     
         15 . A process for forming a three-dimensional article comprising: 
 (1) coating a layer of a composition onto a surface, wherein the composition is defined as in anyone of claims  1 - 12 ;    (2) exposing the layer imagewise to actinic radiation to form an imaged cross-section, wherein the radiation is of sufficient intensity to cause substantial curing of the layer in the exposed areas;    (3) coating a 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-dimensional article.    
     
     
         16 . The process of  claim 15 , wherein the actinic radiation is in the range of 280-650 nm.  
     
     
         17 . The process of  claim 15  or  16 , wherein the exposure energy is in the range of 10-150 mJ/cm.