Photopolymerizable dental composites with rapid curing and low shrinkage stress

1 . A radically polymerizable material, comprising

(a) 0.01 to 5 wt.-% of at least one transfer reagent,

(b) 5 to 60 wt.-% of at least one multifunctional (meth)acrylate or of a mixture of mono- and multifunctional (meth)acrylates,

(c) 0.01 to 3.0 wt.-% of a mixture of at least one monomolecular and at least one bimolecular photoinitiator,

(d) 30 to 90 wt.-% of at least one filler, and

(e) optionally additive(s), in each case relative to the total mass of the material,

wherein the at least one monomolecular photoinitiator comprises a tetraacylgermanium compound,

wherein the material comprises as transfer reagent (a) at least one allyl sulfone of Formula I

in which the variables have the following meanings:

A H; —CN; a phenyl radical, which can bear one or more substituents, such as —CH 3 , —C 2 H 5 , —OH, —OCH 3 , —O—COCH 3 , a polymerizable vinyl, (meth)acryloyloxy or (meth)acrylamide group, or an aliphatic linear or branched C 1 -C 20 alkylene or C 1 -C 20 alkyl radical, which can be interrupted by one or more 1,4-phenylene groups, urethane groups, O or S, which can bear one or more substituents, such as —OH or —OCH 3 , and which can bear a tri-C 1 -C 4 alkoxysilyl group or a polymerizable vinyl, (meth)acryloyloxy or (meth)acrylamide group terminally;

R 1 in each case independently of one another H, an aliphatic linear or branched C 1 -C 9 alkyl radical, tolyl or phenyl;

R 2 in each case independently of one another a phenyl radical, which can bear one or more substituents, such as —CH 3 , —C 2 H 5 , —OH, —OCH 3 , —O—COCH 3 , a polymerizable vinyl, (meth)acryloyloxy or (meth)acrylamide group, —C(═CH 2 )—COOR 3 or —C(═CH 2 )—CO—NR 4 R 5 ; or an aliphatic linear or branched C 1 -C 20 alkyl radical, which can be interrupted by O or S and which can bear a polymerizable vinyl, (meth)acryloyloxy or (meth)acrylamide group, —C(═CH 2 )—COOR 3 or —C(═CH 2 )—CO—NR 4 R 5 terminally, wherein R 3-5 independently of one another are in each case a linear or branched C 1-6 alkyl radical;

X —COO—, —CON(R 6 )— or is absent, wherein the bonding to A is effected via O or N and wherein

R 6 is H; or an aliphatic linear or branched C 1 -C 20 alkyl radical, which can be interrupted by one or more O or S and which can bear a polymerizable vinyl, (meth)acryloyloxy or (meth)acrylamide group, —C(═CH 2 )—COOR 3 or —C(═CH 2 )—CO—NR 4 R 5 terminally, wherein R 3-5 independently of one another are in each case a linear or branched C 1-6 alkyl radical;

n an integer from 1 to 6,

a vinyl sulfone ester of Formula II,

in which the variables have the following meanings:

B H, CN, a cycloaliphatic, linear or branched aliphatic C 1 -C 30 hydrocarbon radical, which can be substituted by one or more substituents, which can be interrupted by one or more urethane groups, ester groups, O and/or S and which can contain 1 to 4 benzene groups,

an aromatic C 6 -C 30 hydrocarbon radical, which can be substituted by one or more substituents,

or a combination thereof;

Y —COO—, —CON(R 7 )— or is absent, wherein the bonding to B is effected via O or N;

C a cycloaliphatic, linear or branched aliphatic C 1 -C 30 hydrocarbon radical, which can be substituted by one or more substituents, which can be interrupted by one or more urethane groups, ester groups, O and/or S and which can contain 1 to 4 benzene groups,

an aromatic C 6 -C 30 hydrocarbon radical, which can be substituted by one or more substituents,

or a combination thereof;

R 7 hydrogen, a cycloaliphatic, linear or branched aliphatic C 1 -C 10 hydrocarbon radical, which can be interrupted by one or more oxygen atoms and which can be substituted by one or more OH groups, or

an aromatic C 6 -C 10 hydrocarbon radical, which can be substituted by one or more OH groups;

p an integer from 1 to 6;

k an integer from 1 to 6;

q an integer from 1 to 6; wherein

p and q cannot be greater than 1 at the same time and wherein if p=1, q=k, and if q=1, p=k; and

wherein the material does not contain a monoacylphosphine oxide, a bisacylphosphine oxide or a mixture thereof.

2 . The material according to claim 1 , in which the variables of Formula I have the following meanings:

A H; an aliphatic linear or branched C 1 -C 14 alkylene or C 1 -C 14 alkyl radical, which can be interrupted by one or more O or S, which can bear one or more substituents, such as —OH or —OCH 3 , and which can bear a tri-C 1 -C 3 alkoxysilyl group or a polymerizable vinyl, (meth)acryloyloxy or (meth)acrylamide group terminally;

R 1 H, an aliphatic branched or preferably linear C 1 -C 4 alkyl radical, tolyl or phenyl;

R 2 in each case independently of one another a phenyl radical, which can bear one or more substituents, such as —CH 3 , —C 2 H 5 , —OH, —OCH 3 , —O—COCH 3 ; or an aliphatic linear or branched C 1 -C 10 alkyl radical, which can be interrupted by O or S;

X —COO—, —CON(R 6 )— or is absent, wherein the bonding to A is effected via O or N and wherein

R 6 H; or an aliphatic linear or branched C 1 -C 10 alkyl radical, which can be interrupted by one or more O or S;

n an integer from 1 to 3,

and/or

in which the variables of Formula II have the following meanings:

B H, a cycloaliphatic, linear or branched aliphatic C 1 -C 15 hydrocarbon radical, which can be substituted by 1 to 4 substituents comprising —CH 3 , —C 2 H 5 , —OH, —OCH 3 and/or —O—COCH 3 , which can be interrupted by 1 to 4 urethane groups, ester groups, O and/or S and which can contain 1 or 2 benzene groups,

an aromatic C 6 -C 18 hydrocarbon radical, which can be substituted by 1 to 6 substituents comprising-CH 3 , —C 2 H 5 , —OH, —OCH 3 and/or —O—COCH 3 ,

or a combination thereof;

Y —COO—, —CON(R 7 )— or is absent, wherein the bonding to B is effected via O or N;

C a cycloaliphatic, linear or branched aliphatic C 1 -C 15 hydrocarbon radical, which can be substituted by 1 to 4 substituents comprising C 1 -C 4 alkyl, —OH, —O—COCH 3 and/or C 1 -C 4 alkoxy, which can be interrupted by 1 to 4 urethane groups, ester groups, O and/or S and which can contain 1 or 2 benzene groups,

an aromatic C 6 -C 18 hydrocarbon radical, which can be substituted by 1 to 6 substituents comprising vinyl, C 1 -C 4 alkyl, —OH, —O—COCH 3 and/or C 1 -C 4 alkoxy, or tosyl,

or a combination thereof;

R 7 hydrogen, a cycloaliphatic, linear or branched aliphatic C 1 -C 6 hydrocarbon radical, which can be interrupted by one or more oxygen atoms and which can be substituted by one or more OH groups, or

an aromatic C 6 -C 10 hydrocarbon radical, which can be substituted by one or more OH groups;

p an integer from 1 to 3;

k an integer from 1 to 3;

q an integer from 1 to 3; wherein

p and q cannot be greater than 1 at the same time and wherein if p=1, q=k, and if q=1, p=k.

3 . The material according to claim 2 , wherein the at least one transfer reagent (a) according to Formula I is selected from 2-(toluene-4-sulfonylmethyl)-acrylic acid ethyl ester (TSMEA), 2-(toluene-4-sulfonylmethyl)-acrylic acid 2-(2-ethoxyethoxy)-ethyl ester, 2-(toluene-4-sulfonylmethyl)-acrylic acid, 2-(toluene-4-sulfonylmethyl)acrylic acid tert-butyl ester, 3-(trimethoxysilyl)propyl-2-(tosylmethyl) acrylate, 3-(triethoxysilyl)propyl-2-(tosylmethyl) acrylate, 3-(triethoxysilyl)propyl-2-(tosylmethyl)acrylamide, 2-(methylsulfonylmethyl)-ethyl acrylate, 2-(methylsulfonylmethyl)-propyl acrylate, triethylene glycol bis[2-(toluene-4-sulfonylmethyl) acrylate], 2-(toluene-4-sulfonylmethyl)-acrylic acid (2-methacryloyloxyethyl) ester, 2-(toluene-4-sulfonylmethyl)-acrylic acid (6-methacryloyloxyhexyl) ester, 2-(toluene-4-sulfonylmethyl)-acrylic acid (10-methacryloyloxydecyl) ester, 2-(toluene-4-sulfonylmethyl)-acrylic acid (2-hydroxy-3-methacryloyloxypropyl) ester, 2-(toluene-4-sulfonylmethyl)-acrylic acid (8-methacryloyloxy-3,6-dioxaoctyl) ester,

and/or

wherein the at least one transfer reagent (a) according to Formula II is selected from 2-(toluene-4-sulfonyloxy)acrylic acid ethyl ester (TSVEA), 2-methanesulfonyloxyacrylic acid ethyl ester, triethylene glycol bis[2-(toluene-4-sulfonyloxy) acrylate], 2-(2,4,6-triisopropyl-benzenesulfonyloxyacrylic acid octyl ester, 2-(toluene-4-sulfonyloxy)-acrylic acid 2-(tetrahydropyran-2-yloxy)-ethyl ester, 2-(toluene-4-sulfonyloxy)-acrylic acid 2-hydroxyethyl ester, 2-(toluene-4-sulfonyloxy)-acrylic acid 2,4,6-trimethylphenyl ester, 2-(4-vinylbenzenesulfonyloxy)-acrylic acid ethyl ester, 2-(toluene-4-sulfonyloxy)-acrylic acid methoxymethyl ester, 2-(2,4,6-triisopropylbenzenesulfonyloxy)-acrylic acid methoxymethyl ester, 2-(2,4,6-triisopropylbenzenesulfonyloxy)-acrylic acid or diethyl-2,2′-[(1,3-phenyldisulfonyl)bis(oxy)] diacrylate.

4 . The material according to claim 1 , comprising as component (b) at least one multifunctional (meth)acrylate selected from the group consisting of bisphenol A dimethacrylate, bis-GMA (an addition product of methacrylic acid and bisphenol A diglycidyl ether), 2-[4-(2-(meth)acryloyloxyethoxyethoxy)phenyl]-2-[4-(2-methacryloyloxyethoxy)phenyl]propane), 2,2-bis[4-(2-methacryloxypropoxy)phenyl]propane (bis-PMA), UDMA (an addition product of 2-hydroxyethyl methacrylate and 2,2,4- or 2,4,4-trimethylhexamethylene-1,6-diisocyanate) and bismuthacryloyloxymethyltricyclo[5.2.1.]decane (TCDMA).

5 . The material according to claim 1 , comprising as the at least one monomolecular photoinitiator a diacyldialkylgermanium or tetraacylgermanium compound, a monoacylphosphine oxide or a mixture thereof; and as the at least one bimolecular photoinitiator camphorquinone (CQ), 9,10-phenanthrenequinone, 1-phenylpropane-1,2-dione, 2,2-dimethoxy-2-phenylacetophenone, diacetyl, 4,4′-dichlorobenzil or a combination of camphorquinone (CQ), 9,10-phenanthrenequinone, 1-phenylpropane-1,2-dione, 2,2-dimethoxy-2-phenylacetophenone, diacetyl, 4,4′-dichlorobenzil with an amine selected from 4-(dimethylamino)-benzoic acid ester (EDMAB), N,N-dimethylaminoethyl methacrylate, N,N-dimethylsym-xylidine, triethanolamine or a mixture thereof.

6 . The material according to claim 1 , wherein the at least one monomolecular photoinitiator is bis(4-methoxybenzoyl)diethylgermane (MBDEGe); the at least one bimolecular photoinitiator is selected form a combination of camphorquinone (CQ), 2,2-dimethoxy-2-phenylacetophenone or a mixture thereof with the amine 4-(dimethylamino)-benzoic acid ester (EDMAB).

7 . The material according to claim 1 , in which the at least one monomolecular photoinitiator and the at least one bimolecular photoinitiator are used in a weight ratio of from 2:1 to 1:2.

8 . The material according to claim 5 , in which the bimolecular photoinitiator and the amine are used in a weight ratio of from 1:1 to 1:6.

9 . The material according to claim 1 , wherein the at least one filler (d) is selected from a mixed oxide of SiO 2 and ZrO 2 , a glass powder comprising barium or strontium aluminium silicate glass powder, a radiopaque filler comprising ytterbium trifluoride or a mixed oxide of SiO 2 with ytterbium(III) oxide, a ground prepolymer or a mixture thereof.

10 . The material according to claim 1 , comprising

(a) 0.1 to 5 wt.-% of the at least one transfer reagent of Formula(e) I and/or II,

(b) 8 to 50 wt.-% of the at least one multifunctional (meth)acrylate or of the mixture of mono- and multifunctional (meth)acrylates,

(c) 0.05 to 3.0 wt.-% of the mixture of at least one monomolecular and at least one bimolecular photoinitiator,

(d) 40 to 90 wt.-% of the at least one filler, and

(e) 0 to 5 wt.-% of the additive(s),

in each case relative to the total mass of the material.

11 . The material according to claim 10 , comprising

(a) 0.1 to 5 wt.-% of the at least one transfer reagent of Formula(e) I and/or II,

(b) 10 to 40 wt.-% of at least one multifunctional (meth)acrylate selected from bisphenol A dimethacrylate, bis-GMA (an addition product of methacrylic acid and bisphenol A diglycidyl ether), 2-[4-(2-(meth)acryloyloxyethoxyethoxy)phenyl]-2-[4-(2-methacryloyloxyethoxy)phenyl]propane), 2,2-bis[4-(2-methacryloxypropoxy)phenyl]propane (bis-PMA), UDMA (an addition product of 2-hydroxyethyl methacrylate and 2,2,4- or 2,4,4-trimethylhexamethylene-1,6-diisocyanate), bismuthacryloyloxymethyltricyclo[5.2.1.]-decane (TCDMA) and mixtures thereof,

(c) 0.1 to 2.0 wt.-% of a mixture of a diacyldialkylgermanium and/or tetraacylgermanium with a bimolecular photoinitiator selected from camphorquinone (CQ) and/or 2,2-dimethoxy-2-phenylacetophenone, or a combination of camphorquinone (CQ) and/or 2,2-dimethoxy-2-phenylacetophenone with 4-(dimethylamino)-benzoic acid ester (EDMAB),

(d) 50 to 85 wt.-% filler selected from mixed oxides of SiO 2 and ZrO 2 , glass powders, radiopaque fillers, mixed oxides of SiO 2 with ytterbium(III) oxide, ground prepolymers and mixtures thereof, and

(e) 0.2 to 3 wt.-% additive(s),

in each case relative to the total mass of the material.

12 . The material according to claim 1 for intraoral use for the restoration of damaged teeth, or for intraoral use as dental cement, filling composite or veneering material.

13 . A method of using the material according to claim 1 as material for the extraoral production or repair of dental restorations.

14 . The method according to claim 13 for the production of artificial teeth, prostheses, inlays, onlays, crowns or bridges.

15 . A method of using the material according to claim 1 for the production of shaped bodies by casting, compression moulding or 3D printing.

16 . The material according to claim 1 , which does not contain a bisacylphosphine oxide.

17 . The material according to claim 1 , which contains no monomolecular photoinitiators other than the at least one diacyldialkylgermanium compound or tetraacylgermanium compound.

18 . The material according to claim 1 , comprising 0.1 to 0.9 wt.-% of at least one transfer reagent (a).

19 . The material according to claim 1 , in which the at least one monomolecular photoinitiator and the at least one bimolecular photoinitiator are used in a weight ratio of from 2:1 to 1.1:1.

20 . The material according to claim 1 , in which the at least one monomolecular photoinitiator and the at least one bimolecular photoinitiator are used in a weight ratio of from 1.7:1 to 1.2:1.

21 . The material according to claim 1 , in which the at least one monomolecular photoinitiator and the at least one bimolecular photoinitiator are used in a weight ratio of from 1:1.1 to 1:2.

22 . The material according to claim 1 , in which the at least one monomolecular photoinitiator and the at least one bimolecular photoinitiator are used in a weight ratio of from 1:1.2 to 1:1.7.

23 . The material according to claim 1 , which does not contain a thermolabile radically polymerizable monomer, a photolabile radically polymerizable monomer or a mixture thereof.

24 . The method of claim 13 , comprising curing of the material by exposure for 1 to 10 seconds with a radiance of from 1000 to 12,000 mW/cm 2 .

25 . The method of claim 13 , comprising curing of the material by exposure for 3 seconds with a radiance of from 2700 to 3500 mW/cm 2 or for 2 seconds with a radiance of from 4000 to 6000 mW/cm 2 .

26 . The method of claim 15 , comprising curing of the material by exposure for 1 to 10 seconds with a radiance of from 1000 to 12,000 mW/cm 2 .

27 . The method of claim 15 , comprising curing of the material by exposure for 3 seconds with a radiance of from 2700 to 3500 mW/cm 2 or for 2 seconds with a radiance of from 4000 to 6000 mW/cm 2 .