High refractive index addition-fragmentation agents

Abstract

Addition-fragmentation agents having the following functional groups: 1) a labile addition-fragmentation group that can cleave and reform to relieve strain, 2) at least one high refractive index group, and 3) at least one ethylenically unsaturated, polymerizable group are described.

What is claimed is: 
     
         1 . A curable composition comprising a multifunctional (meth)acrylate and an addition fragmentation agent of the formula: 
       
         
           
           
               
               
           
         
         wherein 
         R 1  is each independently a (hetero)alkyl group or a (hetero)aryl group 
         Y is —O—. —S—, —O—CO—, O—CO—NH—, —N—CO—, or —NR 4 —, where R 4  is H or C 1 -C 4  alkyl; 
         each X 1  is independently —O— or —NR 4 —, where R 4  is H or C 1 -C 4  alkyl, and 
         n is 0 or 1; 
         m is each independently 1 or 2, 
         R 2  is alkyl, aryl, a high refractive index group, or and ethylenically unsaturated polymerizable group; 
         at least one of said R 2  groups is a high refractive index group; 
         at least one of said R 2  groups comprises an ethylenically unsaturated, polymerizable group; and 
         said addition-fragmentation agent having a refractive index of ≥1.50. 
       
     
     
         2 . The curable composition of  claim 1 , wherein said ethylenically unsaturated, polymerizable group is a (meth)acryloyl group. 
     
     
         3 . The curable composition of  claim 1  wherein at least two of said R 2  groups is a high refractive index group. 
     
     
         4 . The curable composition of  claim 1 , wherein at least two of said R 2  groups is a (meth)acryloyl group. 
     
     
         5 . The curable composition of  claim 1 , wherein at least one of said R 1 —Y—R 2  groups is of the formula: 
       
         
           
           
               
               
           
         
       
       wherein
 R 4  is H or C 1 -C 4  alkyl; 
 X 1  is independently —O— or —NR 4 —, where R 4  is H or C 1 -C 4  alkyl; and 
 t is 2 to 10, said —(C t H 2t )— group optionally substituted by a hydroxy. 
 
     
     
         6 . The curable composition of  claim 1 , wherein the high refractive index group is selected from benzyl, 2-, 3-, and 4-biphenyl, 1-, 2,3-, 4-, and 9-fluorenyl, 4-(1-methyl-1-phenethyl)phenoxyethyl; phenylthio; 1-, 2-, 3- and 4-napthyl, 1- and 2-naphthylthio; 2,4,6-tribromophenoxy; 2,4-dibromophenoxy; 2-bromophenoxy; 1-, and 2-naphthyloxy; 3-phenoxy-; 2-, 3- and 4-phenylphenoxy; 2,4-dibromo-6-sec-butylphenyl; 2,4-dibromo-6-isopropylphenyl; 2,4-dibromophenyl; pentabromobenzyl and pentabromophenyl. 
     
     
         7 . The curable composition of  claim 1  where said addition-fragmentation agent is of the formula: 
       
         
           
           
               
               
           
         
         wherein 
         R RI  comprises a high refractive index group; 
         R polmn  comprises an ethylenically unsaturated, polymerizable group; 
         R 32  is either R RI  or R polmn ; 
         R 33  is alkyl or aryl, an ethylenically unsaturated polymerizable group or a high refractive index group; 
         Y is —O—. —S—, —O—CO—, O—CO—NH—, —N—CO—, or —NR 4 —, where R 4  is H or C 1 -C 4  alkyl; 
         each X 1  is independently —O— or —NR 4 —, where R 4  is H or C 1 -C 4  alkyl, and 
         n is 0 or 1; 
         each o is independently 1 or 2, 
         each p is independently 0 or 1, 
         with the proviso that the addition fragmentation agent comprises at least two ethylenically unsaturated polymerizable group and at least two high refractive index group. 
       
     
     
         8 . The curable composition of  claim 1 , comprising the addition-fragmentation agent, at least one multifunctional (meth)acrylate, and further comprising at least one free-radically polymerizable monomer, and an initiator. 
     
     
         9 . The curable composition of  claim 8  comprising:
 a) 85 to 100 parts by weight of an (meth)acrylic acid ester; 
 b) 0 to 15 parts by weight of an acid functional ethylenically unsaturated monomer; 
 c) 0 to 10 parts by weight of a non-acid functional, ethylenically unsaturated polar monomer; 
 d) 0 to 5 parts vinyl monomer; and 
 e) 0.01 to 5 parts of a multifunctional (meth)acrylate; 
 based on 100 parts by weight total monomer a) to e), and 
 f) 0.1 to 10 parts by weight of the addition-fragmentation agent, based on 100 parts by weight of a) to e). 
 
     
     
         10 . The curable composition of  claim 9  further comprising an inorganic filler. 
     
     
         11 . An article comprising a layer of the curable composition of  claim 10  on a substrate. 
     
     
         12 . A hardcoat composition comprising the curable composition of  claim 1  comprising up to 100 parts by weight of multifunctional (meth)acrylates and 0.1 to 10 parts of the addition-fragmentation agent, relative to 100 parts total monomer. 
     
     
         13 . The hardcoat composition of  claim 12  comprising:
 a) 0.1-10 wt. % of the addition fragmentation agent; 
 b) 20-80 wt. % of multifunctional (meth)acrylate monomers and/or multifunctional (meth)acrylate oligomers, 
 c) 0 to 25 wt. % range of (meth)acrylate diluent; and 
 d) 20 to 75 wt. % of silica. 
 
     
     
         14 . The hardcoat composition of  claim 12  comprising
 i. 85 to 99.5 parts by weight of an (meth)acrylic acid ester; 
 ii. 0 to 15 parts by weight of an acid functional ethylenically unsaturated monomer; 
 iii. 0 to 15 parts by weight of a non-acid functional, ethylenically unsaturated polar monomer; 
 iv. 0 to 5 parts vinyl monomer; 
 vii. 0.1 to 100 parts of a multifunctional (meth)acrylate, relative to i-iv; 
 viii. 0 to 5 parts of a polymerizable photoinitiator; and 
 
       0.1 to 10 parts of the addition-fragmentation agent, relative to 100 parts total monomer i. to v. 
     
     
         15 . A curable dental composition comprising the curable composition of  claim 1  comprising:
 a) at least one dental resin comprising a multifunctional (meth)acrylate having at least two ethylenically unsaturated group; 
 b) the addition-fragmentation agent; and 
 c) optionally an inorganic oxide filler; 
 said addition-fragmentation agent having a refractive index of ≥1.50. 
 
     
     
         16 . The curable dental composition of  claim 15  wherein the dental resin comprises an aromatic monomer having a refractive index of at least 1.50. 
     
     
         17 . The dental composition of  claim 15  wherein the dental resin is a low volume shrinkage resin. 
     
     
         18 . The dental composition of  claim 15  further comprising a nanoparticle inorganic oxide filler. 
     
     
         19 . The curable dental composition of  claim 15  having a cusp deflection, when cured, of no greater than 2.0 microns and a Watts shrinkage of less than 2%. 
     
     
         20 . The curable dental composition of  claim 17  wherein the low shrinkage monomer is of the formula: 
       
         
           
           
               
               
           
         
       
       wherein: each X 1  is independently —O— or —NR 4 —, where R 4  is H or C 1 -C 4  alkyl;
 D and E each independently represent an organic group, and R 12  represents —C(O)C(CH 3 )═CH 2 , and/or p=0 and R 12  represents H, —C(O)CH═CH 2 , or —C(O)C(CH 3 )═CH 2 , with the proviso that at least one R 12  is a (meth)acrylate; each m is 1 to 5; p and q are independently 0 or 1.