Photopolymerizable compositions featuring novel amine accelerator for improved color stability and reduced polymerization stress thereby
A photopolymerization accelerator composition improving color stability and controlling polymerization shrinkage stress of cured resin and/or the resulting composite paste thereby feature by tertiary twisted biphenyldiamine with the general formula I: R2 and R3 are each independently alkyl having from 1 to 5 carbon atoms; R and R1 are each independently hydrogen or halogen; alkyl, alkoxy, or alkylthio having from 1 to 18 carbon atoms; or phenyl and/or substituted phenyl alkoxy, or alkylthio having from 1 to 18 carbon atoms. It can be used in part with conventional photosensitizers and radically polymerizable monomers.
1. A photopolymerizable composition comprising:
a 2-substituted biphenyl tertiary diamine having a twisted biphenyl moiety, a photosensitizer, and at least one curable resin;
wherein the at least one curable resin comprises at least one of a monofunctional (meth)acrylate or a polyfunctional (meth)acrylate; and
wherein the 2-substituted biphenyl tertiary diamine having the twisted biphenyl moiety has the structure:
wherein at least one of R and R1 independently of one another or R and R1 together of the same to each other are an O-, S- or N containing 5- or 6-membered heterocyclic ring; and
wherein each R2 and each R3 independently of one another or together of the same to each other is selected from the group consisting of: alkyl having from C1 to C18 carbon atoms; and CH 2 R5, wherein R5 is selected from the group consisting of: C1-C2 alkyl or fluorinated alkyl; C2-C8 alkyl or fluorinated alkyl interrupted by one or more O atoms; phenyl-substituted C1-C4 alkyl; C2-C18 alkenyl; phenyl which is unsubstituted or is substituted from one to five times by halogen, hydroxyl, C1-C8 alkyl and/or C1-C8 alkoxyl; naphthyl which is unsubstituted or substituted one to five times by halogen, hydroxyl, C1-C8 alkyl and/or C1-C8 alkoxyl; biphenyl which is unsubstituted or substituted from one to five times by halogen, hydroxyl, C1-C8 alkyl and/or C1-C8 alkoxyl, C3-C12 cycloalkyl; and an O- or N-containing 5- or 6-membered heterocyclic ring.
2. A composition as in claim 1 , wherein at least one of R and R1 is an electron-withdrawing group.
3. A composition as in claim 2 , wherein the 2-substituted biphenyl tertiary diamine having the twisted biphenyl moiety is present in the amount of 0.05-1.5% wt/wt.
4. A composition as in claim 1 , wherein the O-, S- or N containing 5- or 6-membered heterocyclic ring is selected from the group consisting of furyl, pyrrolyl, dioxinyl, and pyridyl.
5. A composition as in claim 1 , wherein each R2 and each R3 independently of one another or together of the same to each other is an alkyl having from 1 to 5 carbon atoms.
6. A composition as in claim 1 , wherein alkyl each R2 and each R3 independently of one another or together of the same to each other is an alkyl having from 1 to 18 carbon atoms.