U.S. patent application number 16/642163 was filed with the patent office on 2021-03-11 for dental composition comprising a particulate carrier supporting a coinitiator.
This patent application is currently assigned to DENTSPLY SIRONA INC.. The applicant listed for this patent is DENTSPLY DETREY GMBH. Invention is credited to Joachim E. KLEE, Maximilian MAIER, Caroline RENN, Christian SCHEUFLER, Florian SZILLAT.
Application Number | 20210069069 16/642163 |
Document ID | / |
Family ID | 1000005254603 |
Filed Date | 2021-03-11 |
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United States Patent
Application |
20210069069 |
Kind Code |
A1 |
MAIER; Maximilian ; et
al. |
March 11, 2021 |
DENTAL COMPOSITION COMPRISING A PARTICULATE CARRIER SUPPORTING A
COINITIATOR
Abstract
The present invention relates to a dental composition comprising
a photoinitiator system comprising a particulate carrier supporting
a coinitiator covalently bonded to the surface of the carrier.
Furthermore, the present invention relates to a use of the
particulate carrier in a dental composition. The particulate
carrier displays multiple covalently bonded tertiary amino groups
and/or tertiary phosphine groups on the surface, for crosslinking
monomers, oligomers and/or polymers having one or more
polymerizable double bonds.
Inventors: |
MAIER; Maximilian;
(Osnabruck, DE) ; KLEE; Joachim E.; (Radolfzell,
DE) ; SCHEUFLER; Christian; (Engen, DE) ;
RENN; Caroline; (Singen, DE) ; SZILLAT; Florian;
(Konstanz, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
DENTSPLY DETREY GMBH |
Konstanz |
|
DE |
|
|
Assignee: |
DENTSPLY SIRONA INC.
YORK
PA
|
Family ID: |
1000005254603 |
Appl. No.: |
16/642163 |
Filed: |
August 29, 2018 |
PCT Filed: |
August 29, 2018 |
PCT NO: |
PCT/EP2018/073231 |
371 Date: |
February 26, 2020 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61K 6/62 20200101; A61K
6/40 20200101; A61K 6/889 20200101; A61K 6/17 20200101; A61K 6/30
20200101 |
International
Class: |
A61K 6/889 20060101
A61K006/889; A61K 6/62 20060101 A61K006/62; A61K 6/40 20060101
A61K006/40; A61K 6/30 20060101 A61K006/30; A61K 6/17 20060101
A61K006/17 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 31, 2017 |
EP |
17188788.8 |
Claims
1. A dental composition comprising (a) a compound having a
polymerizable double bond, (b) a photoinitiator system comprising
(b1) a photosensitizer absorbing light in the range of from 400 to
800 nm, and (b2) a particulate carrier supporting a coinitiator
covalently bonded to the surface of the carrier, wherein the
coinitiator is selected from a compound having a tertiary amino
group and/or a compound having a tertiary phosphino group; wherein
the particulate carrier displays multiple covalently bonded
tertiary amino groups and/or tertiary phosphine groups on the
surface, for crosslinking monomers, oligomers and/or polymers
having one or more polymerizable double bonds; wherein the
covalently bonded tertiary amino groups and/or tertiary phosphine
groups are selected from moieties of the following formulae (I) and
(II): ##STR00027## wherein R.sup.1 and R.sup.2 which may be a same
or different, and independently represent a C.sub.1-6
straight-chain alkyl group, C.sub.3-6 branched alkyl group or
cyclic alkyl group; and ##STR00028## wherein L is a single bond or
a divalent linker group.
2. The dental composition according to claim 1, wherein the
particulate carrier is selected from a microparticle or a
nanoparticle.
3. The dental composition according to claim 1, wherein the
photosensitizer is a 1,2-diketone compound.
4. The dental composition according to claim 1, wherein the
particulate carrier is a microparticle or nanoparticle comprising
silica, alumina, zirconia, titania, or a mixture thereof.
5. The dental composition according to claim 4, wherein the
nanoparticle has an average particle size of from 1 to 50 nm.
6. The dental composition according to claim 4, wherein the
nanoparticle has a density of covalently bonded tertiary amino
groups and/or tertiary phosphine group of from 0.1 to 100 groups
per nm.sup.2.
7. The dental composition according to 16, wherein the
polycondensate is obtained by (i) hydrolysing a mixture containing
(A) a silica precursor component, and optionally (B) one or more
compounds selected from the group consisting compounds of aluminum,
zinc, titanium, zirconium, tungsten, ytterbium, hafnium, bismuth,
barium, strontium, silver, tantalum, lanthanum, tin, boron, and
cerium; (ii) converting the silica precursor component (A) and the
optionally compounds (B) into a particulate oxide having an average
particle size of from 1 to 50 nm; (iii) treating the particulate
oxide with a silane treatment agent having one or more covalently
bonded tertiary amino groups or tertiary phosphine groups for
obtaining the polycondensate displaying multiple covalently bonded
tertiary amino groups or tertiary phosphine groups on the
surface.
8. (canceled)
9. The dental composition according to claim 1, wherein in formula
(I) or (II), L is a divalent linker group of formula (III)
##STR00029## wherein a is 0 or an integer of from 1 to 10, and Het
is selected from the group consisting of sulfur, oxygen, and a
nitrogen atom substituted with a hydrogen atom or a straight-chain
C.sub.1-6 alkyl group or a branched or cyclic C.sub.3-6 alkyl
group.
10. The dental composition according to claim 1, wherein the dental
composition is selected from the group consisting of dental glass
ionomer cement, a dental cement, a dental adhesive composition, a
dental bonding agent, a dental primer, a dental infiltrant, a pit
and fissure sealant, a dental desensitizing composition, a pulp
capping composition, a dental composite, and a sealing and
protecting composition for naked tooth necks.
11. The dental composition according to claim 10, wherein the
dental composition further comprises (c) a reactive particulate
filler, and (d) a polyacidic polymer which is reactive with the
reactive particulate filler in a cement reaction.
12. The dental composition according to claim 1, wherein (a) the
compound having a polymerizable double bond is selected from (a1) a
water-soluble, hydrolysis-stable monomer having a single
polymerizable double bond and optionally a carboxylic acid group or
hydroxyl group; and (a2) a water-soluble, hydrolysis-stable
polymerizable crosslinker having at least two polymerizable
carbon-carbon double bonds.
13. A method of forming a dental composition, the method
comprising: polymerizing a compound having a polymerizable double
bond with a photosensitizer absorbing light in the range of from
400 to 800 nm and a particulate carrier displaying multiple
covalently bonded tertiary amino groups and/or tertiary phosphine
groups on the surface, wherein the covalently bonded tertiary amino
groups and/or tertiary phosphine groups are selected from moieties
of the following formulae (I) and (II): ##STR00030## wherein
R.sup.1 and R.sup.2 which may be a same or different, and
independently represent a C.sub.1-6 straight-chain alkyl group,
C.sub.3-6 branched alkyl group or cyclic alkyl group; and
##STR00031## wherein L is a single bond or a divalent linker
group.
14. The method according to claim 13, wherein the particulate
carrier is a nanoparticle or a microparticle.
15. The method according to claim 14, wherein the particulate
carrier is a polycondensate.
16. The dental composition according to claim 2, wherein the
nanoparticle is a polycondensate.
17. The dental composition according to claim 4, wherein the
microparticle has an average particle size of from 0.05 to 50 .mu.m
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a dental composition
comprising a photoinitiator system comprising a particulate carrier
supporting a coinitiator covalently bonded to the surface of the
carrier. Furthermore, the present invention relates to a use of the
particulate carrier in a dental composition.
[0002] The particulate carrier displays multiple covalently bonded
tertiary amino groups and/or tertiary phosphine groups on the
surface, for crosslinking monomers, oligomers and/or polymers
having one or more polymerizable double bonds.
BACKGROUND OF THE INVENTION
[0003] EP3124477 discloses an aqueous dental composition having a
pH of at most 7 which may contain filler particles treated with a
coupling agent in order to enhance the bond between the filler and
the matrix, whereby coupling agents include
gamma-aminopropyltrimethoxysilane. None of the coinitiators of an
initiator system essentially present in a dental composition
disclosed in EP3124477 is linked to a particulate carrier.
[0004] The restoration of teeth commonly involves a light curable
dental composition containing free-radically polymerizable resins.
Light curing of a dental composition involves a photoinitiator
system generating free radicals upon exposure to visible light.
Free radicals may be typically produced by either of two pathways:
[0005] (1) the photoinitiator compound undergoes excitation by
energy absorption with subsequent decomposition into one or more
radicals (Norrish type I), or [0006] (2) the photoinitiator
compound undergoes excitation and the excited photoinitiator
compound interacts with a coinitiator compound by either energy
transfer or a redox reaction to form free radicals from any of the
compounds (Norrish type II).
[0007] In order for a photoinitiator to be useful in a dental
composition, the quantum yield indicating the efficiency of the
conversion of radiation to radicals needs to be high since
absorption or shielding of light by further components of the
dental composition limit the amount of energy available for
absorption by the photoinitiator. Accordingly, only about 70
percent conversion of the polymerizable groups may be expected in a
polymerization of a typical dental composition, whereby the
mechanical strength of the polymerized dental composition is less
than optimal and unreacted monomers may leach out of the
polymerized dental composition. Leaching monomers may have
detrimental effects. In order to alleviate this problem,
multifunctional monomers are frequently used which are more likely
to be included in the polymer network.
[0008] In addition, photoinitiators are required to have a high
acid resistance, solubility, thermal stability, and storage
stability when incorporated into a dental composition.
[0009] Finally, given that dental compositions usually contain
(meth)acrylate or (meth)acrylamide monomers, free radical
photocuring may be inhibited by the presence of oxygen. Oxygen
inhibition is due to the rapid reaction of propagating radicals
with oxygen molecules to yield peroxyl radicals which are not as
reactive towards carbon-carbon unsaturated double bonds and
therefore do not initiate or participate in any photopolymerization
reaction. Oxygen inhibition may lead to premature chain termination
and, therefore, incomplete photocuring. Nevertheless, a certain
degree of oxygen inhibition on the top surface of the adhesive
layer is required for the bonding to the adjacent restorative.
[0010] Accordingly, the polymerization initiator system has a
critical influence on the quality of the dental material.
Conventionally, camphor quinone optionally in combination with a
tertiary amine, or 2, 4, 6-trimethylbenzoylphenyl phosphinate
(Irgacure.RTM. TPO) are frequently used as photoinitiator system.
However, the presence of amines in acrylate-containing compositions
can cause yellowing in the resulting photocured composition, create
undesirable odours, and soften the cured composition because of
chain transfer reactions and therefore, often require the use of
stabilizers. Moreover, the use of aromatic amines gives rise to
toxicological concerns.
[0011] Furthermore, it is desirable that the photoinitiator system
can be light-activated at a long wavelength in order to avoid
damage of soft tissue during polymerization of the dental
composition in the patient's mouth. Accordingly, the photoinitiator
system is required to contain a chromophoric group efficiently
absorbing light of the desired wavelength in a range of from 400 to
800 nm. However, an increase of the absorption coefficient of the
photoinitiator system increases the coloration of the
photoinitiator system and thereby the coloration of the dental
composition before light curing. Accordingly, it is necessary that
the chromophoric groups are efficiently destroyed during
polymerization so that the coloration of the initiator system
disappears in the polymerized dental composition, the so-called
"photo-bleaching". A destruction of the chromophoric groups during
polymerization may also be useful in increasing the depth of cure
of the dental composition since activating light is not shielded
from unpolymerized layers of the dental composition by the
photoinitiator system present in polymerized layers covering the
unpolymerized layers.
[0012] Typically, for improving the polymerization performance of a
photoinitiator system of a dental composition, a coinitiator, e.g.
in the form of an organic compound having a tertiary amino group or
a tertiary phosphine group, is contained in a dental composition.
For example, dental compositions containing a coinitiator in the
form of an organic compound having a tertiary amino group are
disclosed in WO/2017/017155 and EP 2859876 A2. Dental compositions
containing a coinitiator in the form of an organic compound having
a tertiary phosphine group are for example disclosed in U.S. Pat.
No. 3,534,122 A, WO 2009/147033 A1, WO 2012/045736 A1 and WO
2014/060450 A1.
[0013] The coinitiators disclosed in the above cited documents are
small organic molecules.
SUMMARY OF THE INVENTION
[0014] It is an object of the present invention to provide a dental
composition comprising a photoinitiator system comprising a
photosensitizer and a particulate carrier supporting a coinitiator
covalently bonded to the surface of the carrier, wherein the
particulate carrier provides [0015] no or negligible yellowing upon
curing of the dental composition, [0016] an alleviated leaching
problem of the cured dental composition, and [0017] no or
negligible toxicity.
[0018] Moreover, it is the problem of the present invention to
provide a use of the particulate carrier in a dental
composition.
[0019] According to a first aspect, the present invention provides
a dental composition comprising [0020] (a) a compound having a
polymerizable double bond, [0021] (b) a photoinitiator system
comprising [0022] (b1) a photosensitizer absorbing light in the
range of from 400 to 800 nm, and [0023] (b2) a particulate carrier
supporting a coinitiator covalently bonded to the surface of the
carrier, wherein the particulate carrier displays multiple
covalently bonded tertiary amino groups and/or tertiary phosphine
groups on the surface, for crosslinking monomers, oligomers and/or
polymers having one or more polymerizable double bonds.
[0024] According to a second aspect, the present invention provides
a use of the particulate carrier displaying multiple covalently
bonded tertiary amino groups and/or tertiary phosphine groups on
the surface, in a dental composition for crosslinking polymer
chains formed by polymerizing a compound having a polymerizable
double bond.
[0025] The present invention is based on the recognition that the
particulate carrier (b2) provides a cured dental composition which
has no yellowing or yellowing is significantly reduced compared
with conventional dental compositions exclusively containing
non-covalently bonded coinitiator compounds. In addition, the
leaching problem of the cured dental composition is alleviated.
Besides, the particulate carrier (b2) is harmless or at least has a
significantly reduced toxicity compared with conventional,
non-covalently bonded coinitiator compounds.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0026] The term "polymerizable double bond" as used herein in
connection with compound (a) means any double bond capable of
addition polymerization, in particular free radical polymerization,
preferably a carbon-carbon double bond.
[0027] The term "photoinitiator system" means any system of one or
a mixture of two or more compounds that form free radicals when
activated, e. g. by exposure to light and/or interaction with one
or more further compounds in a photochemical process, whereby
polymerization of polymerizable compounds, such as the compound
having a polymerizable double bond (a), is initiated.
[0028] The term "photosensitizer" as used herein in connection with
the photoinitiator system (b) refers to any chemical compound that
forms free radicals when activated, e. g. by exposure to light or
interaction with a further compound, such as the coinitiator
covalently bonded to the particulate carrier (b2) in a
photochemical process.
[0029] The term "particulate carrier" refers to any particulate
material to which surface a coinitiator having a tertiary amino
group or a tertiary phosphine group can be covalently bond, either
to the particulate material itself by means of any suitable
chemical reaction forming a covalent bond, or by surface treatment
of the particulate material with a coating agent to which the
coinitiator is non-covalently bonded. Any coating agent is suitable
as long as it is suitable for dental compositions. Preferably, the
coating agent is an organosilane.
[0030] The term "coinitiator" used in connection with the
particulate carrier (b2) refers to compounds having a tertiary
amino group and/or tertiary phosphine group which interacts with
the photosensitizer in the generation of radicals initiating a
polymerization reaction.
[0031] The present dental composition provides a cured dental
composition based on a polymerization of a compound having a
polymerizable double bond (a) by free radical polymerization
initiated by the photoinitiator system (b).
[0032] The present invention relates to a dental composition, which
may be used as a dental glass ionomer cement, a dental cement, a
dental adhesive composition, a dental bonding agent, a dental
primer, a dental infiltrant, a pit and fissure sealant, a dental
desensitizing composition, a pulp capping composition, a dental
composite, and a sealing and protecting composition for naked tooth
necks.
[0033] The Compound Having a Polymerizable Double Bond (a)
[0034] The dental composition according to the invention comprises
(a) a compound having a polymerizable bond, which compound is
termed as "compound (a)" hereinafter. The dental composition may
comprise one or a mixture of two or more compounds (a).
[0035] The term "polymerizable double bond" as used herein in
connection with compound (a) means any double bond capable of
addition polymerization, in particular free radical polymerization,
preferably a carbon-carbon double bond, more preferably alkenyl
group(s) and/or vinyl group(s).
[0036] Optionally, compound (a) has a carboxylic acid group or
hydroxyl group to make the compound (a) water-soluble. The term
"water-soluble" used in this connection means that at least 0.1 g,
preferably 0.5 g of compound (a) dissolves in 100 g of water at
20.degree. C.
[0037] Preferably, compound (a) is hydrolysis-stable. The term
"hydrolysis-stable" used in this connection means that the compound
(a) is stable to hydrolysis in an acidic medium, such as in a
dental composition. In particular, the compound (a) does not
contain groups, e.g. as ester groups, which hydrolyse in aqueous
media at pH 3 at room temperature within one month.
[0038] Preferably, compound (a) is (a1) a water-soluble,
hydrolysis-stable monomer having a single polymerizable double bond
and optionally a carboxylic acid group or hydroxyl group, which is
termed as "monomer (a1)" hereinafter.
[0039] More preferably, a water-soluble, hydrolysis-stable monomer
having a single polymerizable double bond and a carboxylic acid
group is a compound represented by the general formula (IV):
##STR00001##
[0040] In formula (IV), R.sup.3 is a hydrogen atom or a straight
chain or branched C.sub.1-3 alkyl group, and R.sup.4 is a hydrogen
atom or a straight-chain or branched C.sub.1-6 alkyl group which
may be substituted by a --COOH group. In formula (IV), the dotted
line indicates that R.sup.3 may be in either the cis or trans
orientation. Preferably, R.sup.3 is a hydrogen atom, and R.sup.4 is
a hydrogen atom or a C.sub.1-3 alkyl group optionally substituted
with a --COOH group. More preferably, R.sup.3 is a hydrogen atom,
and R.sup.4 is a hydrogen atom or a methyl group substituted with a
--COOH group, that is compound of formula (IV) is acrylic acid or
itaconic acid. Most preferably, the compound of formula (IV) is
acrylic acid.
[0041] It is preferred that in formula (IV), residues R.sup.3 and
R.sup.4 are selected with the proviso that the molecular weight of
monomer (a1) is at most 200 Da, preferably at most 150 Da, more
preferably at most 100 Da.
[0042] Monomers (a1) comprising a carboxylic acid group, such as
compounds of formula (IV), are particularly advantageous, since
carboxylic acid groups can undergo a cement reaction with an
optional reactive particulate filler (c) described below, whereby a
further improved setting or curing reaction may be attained.
[0043] Besides of monomer (a1), compound (a) may be a
(meth)acrylate compound which may be selected from the group of
methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl
methacrylate, propyl acrylate, propyl methacrylate, isopropyl
acrylate, isopropyl methacrylate, 2-hydroxyethyl acrylate,
2-hydroxyethyl methacrylate (HEMA), hydroxypropyl acrylate,
hydroxypropyl methacrylate, tetrahydrofurfuryl acrylate,
tetrahydrofurfuryl methacrylate, glycidyl acrylate, glycidyl
methacrylate, the diglycidyl methacrylate of bisphenol A
("bis-GMA"), glycerol mono- and di-acrylate, glycerol mono- and
dimethacrylate, ethyleneglycol diacrylate, ethyleneglycol
dimethacrylate, polyethyleneglycol diacrylate (where the number of
repeating ethylene oxide units vary from 2 to 30),
polyethyleneglycol dimethacrylate (where the number of repeating
ethylene oxide units vary from 2 to 30 especially triethylene
glycol dimethacrylate ("TEGDMA"), neopentyl glycol diacrylate,
neopentyiglycol dimethacrylate, trimethylolpropane triacrylate,
trimethylol propane trimethacrylate, mono-, di-, tri-, and
tetra-acrylates and methacrylates of pentaerythritol and
dipentaerythritol, 1,3-butanediol diacrylate, 1,3-butanediol
dimethacrylate, 1,4-butanedioldiacrylate, 1,4-butanediol
dimethacrylate, 1,6-hexane diol diacrylate, 1,6-hexanediol
dimethacrylate, di-2-methacryloyloxethyl hexamethylene dicarbamate,
di-2-methacryloyloxyethyl trimethylhexanethylene dicarbamate,
di-2-methacryloyl oxyethyl dimethylbenzene dicarbamate,
methylene-bis-2-methacryloxyethyl-4-cyclohexyl carbamate,
di-2-methacryloxyethyl-dimethylcyclohexane dicarbamate,
methylene-bis-2-methacryloxyethyl-4-cyclohexyl carbamate,
di-1-methyl-2-methacrylmethyl-trimethylhexamethylene dicarbamate,
di-1-methyl-2-methacryloxyethyl-dimethylbenzene dicarbamate,
di-1-methyl-2-methacryloxyethyl-dimethylcyclohexane dicarbamate,
methylene-bis-1-methyl-2-methacryloxyethyl-4-cyclohexyl carbamate,
di-1-chloromethyl-2-methacryloxyethyl-hexamethylene dicarbamate,
di-1-chloromethyl-2-methacryloxyethyl-trimethylhexamethylene
dicarbamate, di-1-chloromethyl-2-methacryloxyethyl-dimethylbenzene
dicarbamate,
di-1-chloromethyl-2-methacryloxyethyl-dimethylcyclohexane
dicarbamate, methylene-bis-2-methacryloxyethyl-4-cyclohexyl
carbamate, di-1-methyl-2-methacryloxyethyl-hexamethylene
dicarbamate, di-1-methyl-2-methacryloxyethyl-trimethylhexamethylene
dicarbamate, di-1-methyl-2-methacryloxyethyl-dimethylbenzene
dicarbamate, di-1-methyl-2-methacryloxyethyl-dimethylcyclohexane
dicarbamate,
methylene-bis-1-methyl-2-methacryloxyethyl-4-cyclohexyl carbamate,
di-1-chloromethyl-2-methacryloxyethyl-hexamethylene dicarbamate,
di-1-chloromethyl-2-methacryloxyethyl-trimethylhexamethylene
dicarbamate, di-1-chloromethyl-2-methacryloxyethyl-dimethylbenzene
dicarbamate,
di-1-chloromethyl-2-methacryloxyethyl-dimethylcyclohexane
dicarbamate,
methylene-bis-1-chloromethyl-2-methacryloxyethyl4-cyclohexyl
carbamate, 2,2'-bis(4-methacryloxyphenyl)propane,
2,2'bis(4-acryloxyphenyl)propane,
2,2'-bis[4(2-hydroxy-3-methacryloxy-phenyl)]propane,
2,2'-bis[4(2-hydroxy-3-acryloxy-phenyl)propane,
2,2'-bis(4-methacryloxyethoxyphenyl)propane,
2,2'-bis(4-acryloxyethoxyphenyl)propane,
2,2'-bis(4-methacryloxypropoxyphenyl)propane,
2,2'-bis(4-acryloxypropoxyphenyl)propane,
2,2'-bis(4-methacryloxydiethoxyphenyl)propane,
2,2'-bis(4-acryloxydiethoxyphenyl)propane,
2,2'-bis[3(4-phenoxy)-2-hydroxypropane-1-methacrylate]propane, and
2,2'-bis[3(4-phenoxy)-2-hydroxypropane-1-acryalte]propane,
2-hydroxyethyl acrylamide (HEAA), N,N-dimethyl(meth)acrylamide,
N,N-diethyl(meth)acrylamide, N,N-di-n-propyl(meth)acrylamide, and
N-ethyl-N-methyl(meth)acrylamide may be mentioned. Other suitable
examples compounds (b) are isopropenyl oxazoline, vinyl azalactone,
vinyl pyrrolidone, styrene, divinylbenzene, urethane acrylates or
methacrylates, epoxy acrylates or methacrylates and polyol
acrylates or methacrylates.
[0044] Furthermore, compound (a) may be (a2) a water-soluble,
hydrolysis stable polymerizable crosslinker having at least two
polymerizable carbon-carbon double bonds (a2) is termed as
"crosslinker (a2)" hereinafter.
[0045] The term "polymerizable carbon-carbon double bond" as used
herein in connection with the crosslinker (a2) means any
carbon-carbon double bond capable of addition polymerization, in
particular free radical polymerization, preferably alkenyl group(s)
and/or vinyl group(s).
[0046] Preferably, the crosslinker (a2) is a polymerizable compound
of the following formula (V), which is disclosed in EP2705827 and
WO2014040729:
A-L.sup.c(B).sub.n(V)
wherein [0047] A is a group of the following formula (VI)
[0047] ##STR00002## [0048] X.sup.10 is CO, CS, CH.sub.2, or a group
[X.sup.100Z.sup.10].sub.k, wherein X.sup.100 is an oxygen atom, a
sulfur atom or NH, Z.sup.10 is a straight chain or branched
C.sub.1-4 alkylene group, and k is an integer of from 1 to 10;
[0049] R.sup.5 is a hydrogen atom, [0050] --COOM.sup.10, [0051] a
straight chain or branched C.sub.1-16 alkyl group which may be
substituted by a C.sub.3-6 cycloalkyl group, a C.sub.6-14 aryl or
C.sub.3-14 heteroaryl group, --COOM.sup.10, --PO.sub.3M.sup.10,
--O--PO.sub.3M.sup.10.sub.2 or --SO.sub.3M.sup.10, [0052] a
C.sub.3-6 cycloalkyl group which may be substituted by a C.sub.1-16
alkyl group, a C.sub.6-14 aryl or C.sub.3-14 heteroaryl group,
--COOM.sup.10, --PO.sub.3M.sup.10, --O--PO.sub.3M.sup.10.sub.2 or
--SO.sub.3M.sup.10, a C.sub.6-14 aryl or C.sub.3-14 heteroaryl
group which may be substituted by --COOM.sup.10,
--PO.sub.3M.sup.10, --O--PO.sub.3M.sup.10.sub.2 or
--SO.sub.3M.sup.10, [0053] R.sup.6 is a hydrogen atom, [0054]
--OOM.sup.10 [0055] a straight chain or branched C.sub.1-16 alkyl
group which may be substituted by a C.sub.6-14 aryl or C.sub.3-14
heteroaryl group, --COOM.sup.10, --PO.sub.3M.sup.10,
--O--PO.sub.3M.sup.10.sub.2 and --SO.sub.3M.sup.10, a C.sub.3-6
cycloalkyl group which may be substituted by a C.sub.1-16 alkyl
group, a C.sub.6-14 aryl or C.sub.3-14 heteroaryl group,
--COOM.sup.10, --PO.sub.3M.sup.10, --O--PO.sub.3M.sup.10.sub.2 or
--SO.sub.3M.sup.10, or a C.sub.6-14 aryl or C.sub.3-14 heteroaryl
group which may be substituted by --COOM.sup.10,
--PO.sub.3M.sup.10, --O--PO.sub.3M.sup.10.sub.2 and
--SO.sub.3M.sup.10, [0056] L.sup.c is a single bond or a linker
group; [0057] B independently is [0058] a group according to the
definition of A, [0059] a group of the following formula (VII)
[0059] ##STR00003## [0060] wherein [0061] X.sup.20 independently
has the same meaning as defined for X.sup.1 in formula (VI), [0062]
R.sup.5 and R.sup.6 are independent from each other and
independently have the same meaning as defined for formula (VI),
[0063] R.sup.o is a hydrogen atom, [0064] a straight chain or
branched C.sub.1-16 alkyl group which may be substituted by a
C.sub.3-6 cycloalkyl group, a C.sub.6-14 aryl or C.sub.3-14
heteroaryl group, --COOM.sup.10, --PO.sub.3M.sup.10,
--O--PO.sub.3M.sup.10.sub.2 or --SO.sub.3M.sup.10, [0065] a
C.sub.3-6 cycloalkyl group which may be substituted by a C.sub.1-16
alkyl group, a C.sub.6-14 aryl or C.sub.3-14 heteroaryl group,
--COOM.sup.10, PO.sub.3M.sup.10, O--PO.sub.3M.sup.10.sub.2 or
--SO.sub.3M.sup.10, a C.sub.6-14 aryl group which may be
substituted by --COOM.sup.10, --PO.sub.3M.sup.10, --O--PO.sub.3
M.sup.10.sub.2 or --SO.sub.3M.sup.10, [0066] a group of the
following formula (VIII)
[0066] ##STR00004## [0067] wherein [0068] X.sup.30 is CO,
--CH.sub.2CO--, CS, or --CH.sub.2CS--, [0069] R.sup.5 and R.sup.6
which are independent from each other and independently have the
same meaning as defined for formula (VI), or [0070] a group
[X.sup.40Z.sup.200].sub.pE, [0071] wherein [0072] Z.sup.200 is a
straight chain or branched C.sub.1-4 alkylene group, [0073]
X.sup.40 is an oxygen atom, a sulfur atom or NH, [0074] E is a
hydrogen atom, [0075] PO.sub.3M.sub.2, [0076] a straight chain or
branched C.sub.1-16 alkyl group which may be substituted by a
C.sub.3-6 cycloalkyl group, a C.sub.6-14 aryl or C.sub.3-14
heteroaryl group, --COOM.sup.10, --PO.sub.3M.sup.10,
--O--PO.sub.3M.sup.10.sub.2 or --SO.sub.3M.sup.10, a C.sub.3-6
cycloalkyl group which may be substituted by a C.sub.1-16 alkyl
group, a C.sub.6-14 aryl or C.sub.3-14 heteroaryl group,
--COOM.sup.10, --PO.sub.3M.sup.10, --O--PO.sub.3M.sup.10.sub.2 or
--SO.sub.3M.sup.10, [0077] a C.sub.6-14 aryl or C.sub.3-14
heteroaryl group which may be substituted by --COOM.sup.10,
--PO.sub.3M.sup.10, --O--PO.sub.3M.sup.10.sub.2 or
--SO.sub.3M.sup.10, and [0078] p.sup.c is an integer of from 1 to
10; [0079] and [0080] n' is an integer of from 1 to 4; [0081]
wherein M.sup.10 which are independent from each other each
represent a hydrogen atom or a metal atom. Preferably, when L.sup.c
is a single bond, B cannot be a group according to the definition
of A or a group of the formula (VII).
[0082] The following groups are preferred groups of formula (VI),
wherein IV is a hydrogen atom or a metal atom:
##STR00005##
[0083] Preferred divalent linker groups may be selected from
methylene, ethylene, propylene, butylene and the following divalent
groups:
##STR00006##
[0084] N,N'-(2E)-but-2-en-1,4-diallylbis-RN-prop-2-en-1) amide and
N,N-di(allylacrylamido) propane are preferred.
[0085] Alternatively or additionally, compound (a) may be a
crosslinker selected from the group consisting of an alkylenediol
dimethylacrylate such as 1,3-butanediol dimethacrylate,
1,4-butanediol dimethacrylate, an alkylenediol divinyl ether such
as 1,4-butanediol divinyl ether, di(ethylene glycol)
dimethacrylate, di(ethylene glycol) divinyl ether, pentaerythritol
diacrylate monostearate, ethylene glycol dimethacrylate,
trimetylolpropane trimethacrylate, pentaerythritol triacrylate or
triallyl ether, pentaerythritol tetraacrylate and trimetylolpropane
triacrylate.
[0086] Preferably, compound (a) is contained in the dental
composition in an amount of from 0.1 to 20, more preferably 1 to 15
even more preferably 2 to 10 percent by weight based on the total
weight of the dental composition. When compound (a) is absent, no
light-curing of the dental composition is possible. That is, the
dental composition cannot be cured upon irraditation with light. On
the other hand, when the amount of compound (a) exceeds 20 percent
of weight, shrinkage of the cured dental composition may occur.
[0087] The term "photocurable" refers to a dental composition that
will polymerize into a crosslinked polymer network when irradiated
for example with actinic radiation such as ultraviolet (UV),
visible, or infrared radiation. "Actinic radiation" is any
electromagnetic radiation that is capable of producing
photochemical action and can have a wavelength of at least 150 nm
and up to and including 1250 nm, and typically at least 400 nm and
up to and including 800 nm.
[0088] Compound (a) is preferably selected in view of a good
processability and applicability of the final dental composition,
in particular in terms of viscosity. Therefore, the viscosity of
compound (a) is preferably in the range of 0.1 to 100 mPas, more
preferably 0.3 to 50 mPas, even more preferably 0.5 to 25 mPas, yet
even more preferably 0.8 to 10 mPas, in particular 0.9 to 3
mPas.
[0089] The Photoinitiator System (b)
[0090] The dental composition according to the present invention
comprises a photoinitiator system (b) comprising (b1) a
photosensitizer absorbing light in the range of from 400 to 800 nm,
which is termed as "photosensitizer (b1)" hereinafter. The
photoinitiator system (b) may comprise one or a mixture of two or
more photosensitizers (b1).
[0091] Suitable photosensitizers (b1) for the photosensitizer
system (b) are Norrish type I and Norrish type II
photosensitizers.
[0092] The term "Norrish type I" refers to a photosensitizer
undergoing excitation by energy absorption with subsequent
decomposition of the compound into one or more radicals.
[0093] The term "Norrish type II" refers to a photosensitizer
undergoing excitation, and the excited photosensitizer interacts
with a second compound, such as a coinitiator, an electron donor,
or a sensitizer, by either energy transfer or a redox reaction to
form free radicals from any of the compounds.
[0094] Suitable Norrish type I photosensitizers are for example
phosphine oxides or Si- or Ge-acyl compounds.
[0095] Phosphine oxide photosensitizers may have a functional
wavelength range of about 380 nm to about 450 nm, which include
acyl and bisacyl phosphine oxides such as those described in U.S.
Pat. Nos. 4,298,738, 4,324,744 and 4,385,109 and EP 0 173 567.
Specific examples of the acylphosphine oxides include
2,4,6-trimethylbenzoyldiphenylphosphine oxide,
bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide,
dibenzoylphenylphosphine oxide,
bis(2,6-dimethoxybenzoyl)phenylphosphine oxide,
tris(2,4-dimethylbenzoyl)phosphine oxide,
tris(2-methoxybenzoyl)phosphine oxide,
2,6-dimethoxybenzoyldiphenylphosphine oxide,
2,6-dichlorobenzoyldiphenylphosphine oxide,
2,3,5,6-tetramethylbenzoyldiphenylphosphine oxide,
benzoyl-bis(2,6-dimethylphenyl)phosphonate, and
2,4,6-trimethylbenzoylethoxyphenylphosphine oxide. Commercially
available phosphine oxide photosensitizers capable of free-radical
initiation when irradiated at wavelength ranges of greater than
about 380 nm to about 450 nm include
bis(2,4,6-trimethylbenzoyl)phenyl phosphine oxide (IRGACURE 819),
bis(2,6-dimethoxybenzoyl)-(2,4,4-trimethylpentyl) phosphine oxide
(CGI 403), a 25:75 mixture, by weight, of
bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentyl phosphine oxide and
2-hydroxy-2-methyl-1-phenylpropan-1-one (IRGACURE 1700), a 1:1
mixture, by weight, of bis(2,4,6-trimethylbenzoyl)phenyl phosphine
oxide and 2-hydroxy-2-methyl-1-phenylpropane-1-one (DAROCUR 4265),
and ethyl 2,4,6-trimethylbenzylphenyl phosphinate (LUCIRIN
LR8893X). Typically, the phosphine oxide photosensitizer is present
in the composition in catalytically effective amounts, such as from
0.1 percent by weight to 5.0 percent by weight, based on the total
weight of the composition.
[0096] Suitable Si- or Ge-acyl compounds preferably have the
following formula (IX):
X--R.sup.9 (IX) [0097] wherein [0098] X is a group of the following
formula (X):
[0098] ##STR00007## [0099] wherein [0100] M is Si or Ge; [0101]
R.sup.10 represents a substituted or unsubstituted hydrocarbyl or
hydrocarbylcarbonyl group; [0102] R.sup.11 represents a substituted
or unsubstituted hydrocarbyl or hydrocarbylcarbonyl group; [0103]
R.sup.12 represents a substituted or unsubstituted hydrocarbyl
group; and [0104] R.sup.9 i) has the same meaning as X, whereby the
compound of formula (IX) may be symmetrical or unsymmetrical; or
[0105] ii) is a group of the following formula (XI):
[0105] ##STR00008## [0106] wherein [0107] Y represents a single
bond, an oxygen atom or a group NR', wherein R' represents a
substituted or unsubstituted hydrocarbyl group; [0108] R.sup.13
represents a substituted or unsubstituted hydrocarbyl group, a
trihydrocarbylsilyl group, a
mono(hydrocarbyl-carbonyl)dihydrocarbylsilyl group or a
di(hydrocarbyl-carbonyl)monohydrocarbylsilyl group.
[0109] It was surprisingly found that Si- or Ge-acyl compounds of
formula (IX) represent 1,2-diketone photosensitizers which are
particularly suitable for dental compositions. With compounds of
formula (IX), a high polymerization efficiency is attained, and no
coloration problems occur, or in a polymerization system comprising
a conventional photosensitizer such as camphor quinone, coloration
is efficiently suppressed. Furthermore, compounds of formula (IX)
have a light absorption within the wavelength range typically
applied in dental application, they are compatible with the
ingredients of dental compositions and besides, they are considered
physiologically harmless.
[0110] In connection with the Si- or Ge-acyl compound of formula
(IX), the term "substituted" as used herein means that R.sup.10,
R.sup.11, R.sup.12, R.sup.13 and R' may be substituted by a
substituent selected from the group consisting of halogen atoms, a
nitro group, a cyano group, a hydroxy group, an amino group,
C.sub.1-6 alkyl groups, C.sub.1-6 alkoxy groups and a
--NR.sup.xR.sup.y group wherein R.sup.x and R.sup.y independently
from each other represent a C.sub.1-6 alkyl group. Here,
illustrative of the halogen atoms can be fluorine, chlorine,
bromine and iodine. The C.sub.1-6 alkyl groups are, for example,
methyl, ethyl, n-propyl, isopropyl and n-butyl. Illustrative of the
C.sub.1-6 alkoxy groups are, for example, methoxy, ethoxy and
propoxy. The alkyl moieties in these substituents may be linear,
branched or cyclic. Preferably, the substituent is selected from a
chlorine atom, a nitro group, a C.sub.1-4 alkoxy group and a
--NR.sup.xR.sup.y group wherein R.sup.x and R.sup.y independently
from each other represent a C.sub.1-4 alkyl group.
[0111] If R.sup.10, R.sup.11 and R.sup.12 are substituted, then it
is preferred that they are substituted with 1 to 3 substituents,
more preferably with 1 substituent.
[0112] In the compound of formula (IX), moieties R.sup.10, R.sup.11
and R.sup.12 may be defined as follows:
[0113] R.sup.10 and R.sup.11 independently from each other
represent a substituted or unsubstituted hydrocarbyl or
hydrocarbylcarbonyl group, and R.sup.12 represents a substituted or
unsubstituted hydrocarbyl group.
[0114] The hydrocarbyl group may be an alkyl group, a cycloalkyl
group, a cycloalkylalkyl group, an arylalkyl group or an aryl
group.
[0115] An alkyl group may be straight-chain or branched C.sub.1-20
alkyl group, typically a C.sub.1-8 alkyl group. Examples for a
C.sub.1-6 alkyl group can include linear or branched alkyl groups
having 1 to 6 carbon atoms, preferably 1 to 4 carbon atoms, for
example, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl,
sec-butyl, tert-butyl, n-pentyl, isopentyl and n-hexyl.
[0116] A cycloalkyl group may be a C.sub.3-20 cycloalkyl group,
typically a C.sub.3-8 cycloalkyl group. Examples of the cycloalkyl
group can include those having 3 to 6 carbon atoms, for example,
cyclopropyl, cyclobutyl, cyclopentyl and cyclohexyl.
[0117] A cycloalkylalkyl group may have 4 to 20 carbon atoms and
may include a combination of a linear or branched alkyl group
having 1 to 6 carbon atoms and a cycloalkyl group having 3 to 14
carbon atoms. Examples of the cycloalkylalkyl(-) group can for
example, include methylcyclopropyl(-) methylcyclobutyl(-),
methylcyclopentyl(-), methylcyclohexyl(-), ethylcyclopropyl(-),
ethylcyclobutyl(-), ethylcyclopentyl(-), ethylcyclohexyl(-),
propylcyclopropyl(-), propylcyclobutyl(-), propylcyclopentyl(-),
propylcyclohexyl(-).
[0118] An arylalkyl(-) group may be a C.sub.7-20 arylalkyl(-)
group, typically a combination of a linear or branched alkyl group
having 1 to 6 carbon atoms and an aryl(-) group having 6 to 10
carbon atoms. Specific examples of an arylalkyl(-) group are a
benzyl(-) group or a phenylethyl(-) group.
[0119] An aryl group can include aryl groups having 6 to 10 carbon
atoms. Examples of the aryl group are phenyl and naphtyl.
[0120] The hydrocarbylcarbonyl groups of R.sup.10 and R.sup.11
represent acyl groups (R.sub.org--(C.dbd.O)--) in which the organic
residue R.sub.org is a hydrocarbyl residue as defined above.
[0121] Compound of formula (IX) may contain one or two
hydrocarbylcarbonyl groups, that is either one of R.sup.10 or
R.sup.11 is a hydrocarbylcarbonyl group, or both R.sup.10 and
R.sup.11 are hydrocarbylcarbonyl groups. Preferably, compound of
formula (V) contains one hydrocarbylcarbonyl group.
[0122] Preferably, the hydrocarbylcarbonyl group is an arylcarbonyl
group, more preferably a benzoyl group.
[0123] Preferably, R.sup.10 and R.sup.11 are independently selected
from the group consisting of a straight chain or branched C.sub.1-6
alkyl group, and a phenyl or benzoyl group which may optionally be
substituted by one to three substitutents selected from halogen
atoms, a nitro group, a C.sub.1-4 alkoxy group and a
--NR.sup.xR.sup.y group wherein R.sup.x and R.sup.y independently
from each other represent a C.sub.1-4 alkyl group, and R.sup.12 is
a straight chain or branched C.sub.1-6 alkyl group or a phenyl
group.
[0124] Most preferably, R.sup.10 and R.sup.11 are independently
selected from the group consisting of a straight chain or branched
C.sub.1-4 alkyl group, and a phenyl or benzoyl group which may
optionally be substituted with one substituent selected from the
group consisting of selected from a halogen atom, a nitro group, a
C.sub.1-4 alkoxy group and a --NR.sup.xR.sup.y group wherein
R.sup.x and R.sup.y independently from each other represent a
C.sub.1-4 alkyl group, and R.sup.12 is a straight chain or branched
C.sub.1-4 alkyl group.
[0125] In the compound of formula (IX), R.sup.9 may have the same
meaning as X, whereby the compound of formula (IX) may be
symmetrical or unsymmetrical. Alternatively, R.sup.9 may represent
a substituted or unsubstituted hydrocarbyl group, or a group of
formula (XI). Preferably, if R.sup.9 has the same meaning as X,
then compound of formula (IX) is unsymmetrical. If R.sup.9
represents a substituted or unsubstituted hydrocarbyl group, then
the hydrocarbyl group has the same meaning as defined above for
R.sup.10 and is independently selected therefrom.
[0126] In the group of formula (XI) of compound of formula (IX),
R.sup.13 represents a substituted or unsubstituted hydrocarbyl
group, a trihydrocarbylsilyl group, a
mono(hydrocarbylcarbonyl)-dihydrocarbylsilyl group or a
di(hydrocarbylcarbonyl)monohydrocarbylsilyl group.
[0127] If R.sup.13 of formula (XI) is a trihydrocarbylsilyl group,
a mono(hydrocarbylcarbonyl)-dihydrocarbylsilyl group or a
di(hydrocarbylcarbonyl)monohydrocarbylsilyl group, each of the
hydrocarbyl and hydrocarbylcarbonyl groups has the same meaning as
defined for R.sup.10, R.sup.11 and R.sup.12 and is independently
selected therefrom.
[0128] In formula (XI), R' has the same meaning as defined for
R.sup.12 and is independently selected therefrom.
[0129] For example, compounds of formula (IX) wherein R.sup.9 has
the same meaning as X and which are symmetrical may be have the
following structural formulae:
##STR00009##
[0130] For example, compounds of formula (IX) wherein R.sup.9
represents a group of formula (XI) wherein Y is a bond, an oxygen
atom or a NR' group, and R.sup.13 represents a substituted or
unsubstituted hydrocarbyl group may have the following structural
formulae:
##STR00010##
[0131] For example, compounds of formula (IX) wherein R.sup.9
represents a group of formula (XI) wherein R.sup.13 represents a
trihydrocarbylsilyl group have the following structural
formulae:
##STR00011##
[0132] Preferably, compound of formula (IX) is selected from the
group consisting of:
##STR00012##
wherein compounds of formula (IX) with M=Si are particularly
preferred.
[0133] More preferably, compound of formula (IX) has the following
structural formula:
##STR00013##
wherein it is particularly preferred that M=Si. That is, tert-butyl
(tert-butyldimethylsilyl)-glyoxylate) (DKSi) is particularly
preferred.
[0134] In case the dental composition is in the form of an acidic
composition, that is a composition having a pH of less than 7,
depending on the composition's pH level, it is preferred to select
compounds of formula (IX) with the proviso that they do not contain
ester groups, or at least only ester groups which do not
significantly hydrolyse in aqueous media at pH 3 at room
temperature within one month. Thereby, an advantageous stability of
an acidic dental composition, that is a composition having a pH of
less than 7, in terms of shelf-life stability of the uncured dental
composition as well as stability after curing in the mouth of a
patient is ensured. Therefore, for acidic dental compositions,
particularly preferred are compounds of formula (IX) excluding
R.sup.9 being a group of formula (XI) in which Y is an oxygen
atom.
[0135] Furthermore, since the acylsilyl moiety (--C(.dbd.O)--Si--)
might be sensitive to basic conditions, that is a pH higher than 7,
it is preferred to suitably select a pH value of the composition
being higher than 7 with the proviso that the acylsilyl moiety is
not cleaved in aqueous media at the selected basic pH at room
temperature within one month.
[0136] The compound of the formula (IX) may be a known compound
which is commercially available or a may be prepared according to
published procedures, as described for example in WO 2017/060459
A1.
[0137] Suitable Norrish type II photosensitizers may be selected
from the group consisting of camphorquinone, benzil, 2,2'-3 3'- and
4,4'-dihydroxylbenzil, 2,3-butanedione, 2,3-pentanedione,
2,3-hexanedione, 3,4-hexanedione, 2,3-heptanedione,
3,4-heptanedione, 2,3-octanedione, 4,5-octanedionefuril, biacetyl,
1,2-cyclohexanedione, 1,2-naphthaquinone, and acenaphthaquinone.
Camphorquinone is preferred.
[0138] Preferably, irrespective whether Norrish type I or II, the
photosensitizer (b1) is a 1,2-diketone, even more preferably
camphor quinone or a Si- or Ge-acyl compound of formula (IX), yet
even more preferably camphor quinone or DKSi, and most preferably
camphor quinone.
[0139] Besides of the photosensitizer (b1), the photoiniator system
(b) further comprises (b2) a particulate carrier supporting a
coinitiator covalently bonded to the surface of the carrier, which
is termed as "particulate carrier (b2)" hereinafter. The
photoinitiator system (b) may comprise one or a mixture of two or
more particulate carriers (b2).
[0140] The particulate carrier (b2) supports a coinitiator
covalently bonded to the surface of the carrier, wherein the
particulate carrier displays multiple covalently bonded tertiary
amino groups and/or tertiary phosphine groups on the surface, for
crosslinking monomers, oligomers and/or polymers having one or more
polymerizable double bonds.
[0141] It was surprisingly found that the particulate carrier (b2)
provides for a cured dental composition which has no yellowing or
yellowing is significantly reduced compared with conventional
dental composition having exclusively non-covalently bonded
coinitiator compounds. Furthermore, the leaching problem of the
cured dental composition is alleviated. Finally, the particulate
carrier (b2) is harmless or at least has a significantly reduced
toxicity compared with non-covalently bonded coinitiator
compounds.
[0142] Preferably, the covalently bonded tertiary amino groups
and/or tertiary phosphine groups are selected from moieties of the
following formulae (I) and (II):
##STR00014##
[0143] In formula (I), R.sup.1 and R.sup.2, which may be the same
or different, independently represent a C.sub.1-6 straight-chain,
C.sub.3-6 branched or cyclic alkyl group. In formulae (I) and (II),
L is a single bond or a divalent linker group.
[0144] Preferably, in formula (I), R.sup.1 and R.sup.2, which may
be the same or different, independently represent a C.sub.1-4
straight-chain or branched alkyl group, more preferably a C1 or C2
straight-chain alkyl group, most preferably a methyl group.
[0145] For L, the divalent linker group may be a hydrocarbon group
which may be aliphatic and/or aromatic, preferably aliphatic, and
preferably has 1 to 45 carbon atoms. The aliphatic hydrocarbon
group may be saturated or unsaturated. The hydrocarbon group may be
substituted with 1 to 6 C.sub.1-4 alkyl groups. Specific examples
of the alkyl groups are methyl, ethyl, n-propyl, i-propyl, n-butyl,
i-butyl or tert.-butyl. In a preferred embodiment, for L, the
hydrocarbon group of the linker group may contain 1 to 20
heteroatoms selected from oxygen, nitrogen and sulphur. The oxygen
atoms, nitrogen atoms and sulphur atoms in the hydrocarbon group
may be in the form of ether or thioether bonds, amine bonds, keto
or sulfoxide groups, carboxylic acid or ester groups, amide groups,
sulfonic acid or ester groups, hydroxyl groups and thiol or
thioester groups.
[0146] Preferably, the divalent linker group is a divalent
C.sub.1-20 hydrocarbon which may contain one or more heteroatoms
selected from the group of an oxygen atom, a sulfur atom, and a
nitrogen atom. More preferably, the divalent linker group is an
aliphatic group in the form of a linear C.sub.1 to C.sub.20 or
branched C.sub.3 to C.sub.20 alkylene group, linear C.sub.2 to
C.sub.20 and branched C.sub.3 to C.sub.20 alkenylene group, C.sub.3
to C.sub.20 cycloalkylene or cycloalkenylene group which may
contain 1 to 20 heteroatoms selected from oxygen, nitrogen and
sulphur, which heteroatoms may be in the form described above.
[0147] According to one aspect of the invention, the divalent
linker group is a group of the following formula (III):
##STR00015##
[0148] In formula (III), a is 0 or an integer of from 1 to 10, and
Het is selected from the group of sulfur, oxygen, and a nitrogen
atom substituted with a hydrogen atom or a straight-chain C.sub.1-6
alkyl group or a branched or cyclic C.sub.3-6alkyl group.
[0149] According to another aspect of the invention, the divalent
linker group may be an alkylene(polyoxyalkylene) group. The
alkylene(polyoxyalkylene) for the divalent linker group is not
particularly limited, but preferably, it is a C.sub.2-6
alkenylene-(O--C.sub.2-6 alkylene).sub.k wherein k is 1 to 20.
Preferably, the alkylene(polyoxyalkylene) is
ethylene(polyoxyethylene) wherein k is 1 to 10, most preferably 1
to 5.
[0150] Most preferably, in formulae (I) and (II), L is a single
bond.
[0151] The moieties of formulae (I) and (II) may be covalently
bonded to the surface of the particulate carrier via any covalent
bond formed by an organic reaction, preferably a carboxylic acid
ester bond, a carboxylic acid amide bond, a sulfonamide bond, an
oxo- or thio-ether bond, a carbamate bond, a thiocarbamate bond or
an urea bond, more preferably a carboxylic acid ester bond and a
carboxylic acid amide bond, most preferably a carboxylic acid amide
bond.
[0152] Preferably, the particulate carrier is selected from a
microparticle, a nanoparticle and a polycondensate.
[0153] The term "microparticle" means a particle having an average
particle size within the micrometer range, preferably up to 250
.mu.m, more preferably 0.05 to 125 .mu.m, and most preferably 1 to
50 .mu.m.
[0154] The term "nanoparticle" means a particle having an average
particle size within the micrometer range, preferably up to 250 nm,
more preferably 0.05 to 125 nm, and most preferably 1 to 50 nm.
[0155] The term "average particle size" refers to the arithmetic
mean diameter of a particle and may be determined by any suitable
means, such as transmission or high resolution scanning electron
microscopy. The average particle size may be determined as
so-called "D50" value, which is the particle size corresponding to
the volume basis cumulative 50% size.
[0156] The above described microparticle or nanoparticle may for
example be composite particles comprising two or more components,
for example at least one particulate inorganic component such as a
particulate metal oxide and at least one organic component such as
a surface treatment agent, e.g. a silane treatment agent. The
microparticle or nanoparticle may also be a particle essentially
consisting of one component, e.g. of a polycondensate of organic
compounds such as organoalkoxysilanes.
[0157] The term "polycondensate" as used in connection with the
particulate carrier (b2) means any particulate product having
polycondensation reaction products. Polycondensation products are
obtained by a polymerization reaction in which molecules join
together whereby small compounds such as water or an alcohol leave
the molecules. For example, the polycondensate may be any suitable
organic polycondensation reaction product, preferably a
polycondensation reaction product of organoalkoxysilanes.
[0158] The particulate carrier (b2) in the form of a nanoparticle
preferably has a density of covalently bonded tertiary amino groups
and/or tertiary phosphine group of from 0.1 to 100 groups per
nm.sup.2.
[0159] It is preferred that the particulate carrier is a
microparticle or nanoparticle comprising silica, alumina, zirconia,
titania, or a mixture thereof.
[0160] According to a particularly preferred embodiment, the
nanoparticle is a polycondensate obtainable by a process comprising
the following three steps (i) to (iii): [0161] (i) hydrolysing a
mixture containing [0162] (A) a silica precursor component, and
optionally [0163] (B) one or more compounds selected from compounds
of aluminum, zinc, titanium, zirconium, tungsten, ytterbium,
hafnium, bismuth, barium, strontium, silver, tantalum, lanthanum,
tin, boron, and cerium; [0164] (ii) converting the silica precursor
component (A) and the optionally compounds
[0165] (B) into a particulate oxide having an average particle size
of from 1 to 50 nm; [0166] (iii) treating the particulate oxide
with a silane treatment agent having one or more covalently bonded
tertiary amino groups or tertiary phosphine groups for obtaining a
polycondensate displaying multiple covalently bonded tertiary amino
groups or tertiary phosphine groups on the surface.
[0167] In step (i), the silica precursor component (A) is
preferably silicon alkoxide Si(OR.sup.7).sub.4, wherein R.sup.7 is
a linear C.sub.1-8 or branched or cyclic C.sub.3-8 alkyl group,
preferably a linear or branched C.sub.1-4 alkyl group, most
preferably a linear C.sub.1 or C.sub.2 alkyl group. The optional
compound (B) is preferably a metal alkoxide M(OR.sup.8).sub.n,
wherein R.sup.8 has the same meaning as R.sup.7 of the silicon
alkoxide, M is selected from the group consisting of aluminum,
zinc, titanium, zirconium, tungsten, ytterbium, hafnium, bismuth,
barium, strontium, silver, tantalum, lanthanum, tin, boron, and
cerium, and n is an integer of 1 to 4 corresponding to the
oxidation state of the selected M. Preferably M is aluminum,
titanium, zirconium or zirconium.
[0168] The hydrolysing in step (i) is effected by adding water to
the silica precursor component (A) and the optional compound (B),
whereby the corresponding hydroxide is formed from silica precursor
component (A) and optional compound(s) (B), and as a byproduct, an
alcohol is formed.
[0169] In step (ii), converting is a polycondensation reaction in
which from the hydroxide obtained in step (i), a particulate oxide
is formed as polycondensate of the silica precursor component (A)
and the optional compound(s) (B), and water is formed as a
byproduct. The polycondensation reaction is preferably carried out
in a mixture of water and an alcohol, for example ethanol or
methanol.
[0170] Preferably, step (i) and (ii) independently from each other
are base or acid catalyzed. Base catalyzation may preferably be
carried out by setting the pH within a range of more than 7 to 14,
more preferably 9 to 13, most preferably 11 to 12. For base
catalyzation, any suitable basic compound may be used for setting
the pH, for example with ammonia. Acid catalyzation may preferably
be carried out by setting the pH within a range of 0 to less than
7, more preferably 1 to 6, most preferably 2 to 5. For acid
catalyzation, any suitable acidic compound may be used for setting
the pH, for example hydrochloric acid, sulfuric acid and phosphoric
acid.
[0171] The reaction mixture of step (ii) provides a colloidal metal
oxide, which is typically aged for obtaining a gel thereof. Aging
means that the reaction mix is allowed to stand for a predetermined
period of time at a predetermined temperature. For example, aging
may be carried out for 0.5 to 6 h, preferably at a temperature of
15 to 35.degree. C.
[0172] After aging, the resulting gel is typically dried and
calcined for obtaining a particulate oxide. Drying is carried out
to remove water and alcohol. Therefore, the temperature for drying
is suitably selected in view of the alcohol present in the reaction
mixture and in view of the pressure applied. For example, for a
reaction mixture of step (ii) containing water and ethanol, drying
at standard pressure (100 kPa) may be carried out at a temperature
of 100.degree. C. or more. Calcination is carried out to remove
organic species and to convert byproducts formed due to incomplete
reactions in steps (i) and (ii), for example silanols, to the
desired particulate oxide. Preferably, calcination is carried out
at 400 to 1000.degree. C., more preferably 500 to 800.degree. C.,
most preferably 550 to 650.degree. C.
[0173] The combination of steps (i) and (ii) is well known as
sol-gel process in the field of chemistry and described in general
for example in Ullmann's Encyclopedia of Industrial Chemistry, vol.
A. 14, page 248 to 250, 5th edition, 1989, VCH Verlagsgesellschaft
mbH. Specifically, silica sol-gel processes for preparing
nanoparticles are described in I. A. Rahman et al., "Synthesis of
Silica Nanoparticles by Sol-Gel: Size-Dependent Properties, Surface
Modification, and Applications in Silica-Polymer Nanocomposites--A
Review", Journal of Nanomaterials Volume 2012, Article ID 132424,
Hindawi Publishing Corporation.
[0174] Preferably, in step (iii), the silane treatment agent has
one or more covalently bonded tertiary amino groups and/or tertiary
phosphine groups selected from the moieties of the formulae (I) and
(II) described above.
[0175] One preferred silane treatment agent for step (iii) is an
organosilane of formula (XII)
(R.sub.A,R.sub.B,R.sub.C)Si(R.sub.H).sub.n (XII)
are applied, wherein n is 1 to 3 and the number of substituents
R.sub.C, R.sub.B, R.sub.C is 4-n. Preferably, n is 2 or 3, more
preferably 3.
[0176] In formula (XII), R.sub.A, R.sub.B, R.sub.C, which may be
the same or different, represent an unreactive group or a
polymerizable group, and at least one of R.sub.A, R.sub.B, R.sub.C
is substituted with a covalently bonded tertiary amino group and/or
tertiary phosphine group. Unreactive groups for R.sub.A, R.sub.B
and R.sub.C may be represented by alkyl groups, preferably linear
C.sub.1-8 or branched or cyclic C.sub.3-8 alkyl groups.
Polymerizable groups for R.sub.A, R.sub.B and R.sub.C are
preferably selected from the group consisting of a (meth)acryl
group, a vinyl group or an oxirane group, more preferably
(meth)acryl group or a vinyl group, and most preferably a
(meth)acryl group which may be in the form of e.g. methacryloxy or
methacryloxyalkyl wherein alkyl means a linear C.sub.1-8 or
branched or cyclic C.sub.3-8 alkyl group. Preferably, at least one
of R.sub.A, R.sub.B and R.sub.C is a polymerizable group.
[0177] R.sub.H, which may be the same or different if two or three
groups R.sub.H are present, represent(s) a hydrolysable group
capable of reacting with the surface of the filler material to be
coated. R.sub.H may be selected from the group consisting of alkoxy
groups, ester groups, halogen atoms and amino group, wherein the
alkoxy groups are preferably linear C.sub.1-8 or branched or cyclic
C.sub.3-8 alkoxy groups, and the ester groups are preferably
carboxylates having linear C.sub.1-8 or branched or cyclic
C.sub.3-8 alkyl groups. Most preferably, the hydrolysable group
R.sub.H represents an alkoxy group.
[0178] Alternatively or additionally to the organosilane of formula
(XII), a dipodal organosilane of formula (XIII)
((R.sub.H).sub.nSi--R.sub.D).sub.2CH--R.sub.A (XIII)
may be applied. In formula (XIII), R.sub.A and R.sub.H have the
same meaning as defined above for the organosilane of formula
(XII), R.sub.D represents an alkylene group, and n is 1 to 3,
preferably 2 or 3, more preferably 3. Preferably, R.sub.D
represents a linear C.sub.1-8 or branched or cyclic C.sub.3-8
alkylene group, more preferably a linear or branched C.sub.1-4
alkylene group.
[0179] At least one of R.sub.A, R.sub.B, R.sub.C of formula (XII)
and R.sub.A of formula (XIII) is substituted with a tertiary amino
or tertiary phosphine group, which group is preferably selected
from the moieties of formulae (XII) and (XIII) described above.
R.sub.A, R.sub.B, R.sub.C may be substituted with the tertiary
amino or tertiary phosphine group via any covalent bond formed by
an organic reaction, preferably a carboxylic acid ester bond, a
carboxylic acid amide bond, a sulfonamide bond, an oxo- or
thio-ether bond, a carbamate bond, a thiocarbamate bond or an urea
bond, more preferably a carboxylic acid ester bond and a carboxylic
acid amide bond, most preferably a carboxylic acid amide bond.
[0180] For example, organosilanes of formula (XII) or (XIII) with
R.sub.H being an alkoxy group may be prepared analogous to the
synthesis disclosed in EP 1 156 053 A2, which describes how an
organic moiety having for example a tertiary amino group can be
introduced into a trialkoxysilane. The synthesis starts from an
trialkoxysilane having an aminoalkyl, an isocyanatoalkyl or an
thiolalkyl group. The trialkoxysilane is reacted with a compound
having a tertiary amino group in the form of a maleimide group and
a reactive group in the form of a hydroxyl or isocyanate group. The
reactive group is reacted with the amino, isocyanate or thiol group
of the trialkoxysilane. Thereby, the tertiary amino group is
covalently bonded to the trialkoxysilane via a carbamate,
thiocarbamate or urea bond.
[0181] Alternatively, organosilanes of formula (XII) or (XIII) with
R.sub.H being an alkoxy group may for example be prepared analogous
to the synthesis disclosed in WO 00/121967 A1 by reacting a
trialkoxylsilane having an aminoalkyl group with a compound having
an organic moiety and a reactive group in the form of an acyl
halogenide (preferably iodide, chloride, bromide, most preferably
chloride), whereby the organic group is covalently bonded to the
trialkoxysilane via an amide bond.
[0182] For example, an organosilane of formula (XII) in which
R.sub.H is an alkoxy group and one of R.sub.A, R.sub.B, R.sub.C is
substituted with a tertiary amino group covalently bonded by a
carboxylic acid amide group may be prepared starting from a
commercially readily available aminoalkyl trialkoxysilane such as
(3-aminopropyl)trimethoxysilane (CAS-No. 13822-56-5), which is
reacted with an acyl halogenide (preferably iodide, chloride,
bromide, most preferably chloride) compound having the moiety of
formula (I) or (II).
[0183] In addition to the preferred organosilanes of formulae (XII)
and (XIII), in step (iii), conventional organosilanes, that is
organosilanes without a covalently bonded tertiary amino group
and/or tertiary phosphine group may be applied. Particularly
preferred conventional organosilanes are for example 3-methacryloxy
trimethoxysilane, vinyltrichlorosilane, tris
(2-methoxyethoxy)-vinylsilane or tris(acetoxy)-vinylsilane, or any
one of the specific group of organosilanes disclosed in EP 0969789
A1, namely 3-methacryloxypropyltrimethoxysilane,
3-methacryloxypropyldimethoxy-monochlorosilane,
3-methacryloxypropyldichloromonomethoxysilane,
methacryloxypropyltri-chlorosilane,
3-methacryloxypropyldichloromonomethyl-silane and
3-methacryloxypropylmonochlorodimethylsilane.
[0184] Besides of the photosensitizer (b1) and the particulate
carrier (b2), the photoinitiator system (b) may comprise further
components, such as an electron donor component, a coinitiator
component which is not covalently bonded to any component of the
dental composition, and a sensitizer component.
[0185] Preferred electron donor components include, for example,
amides, ethers, thioethers, ureas, thioureas, ferrocene, sulfinic
acids and their salts, salts of ferrocyanide, ascorbic acid and its
salts, dithiocarbamic acid and its salts, salts of xanthates, salts
of ethylene diamine tetraacetic acid and salts of
tetraphenylboronic acid or an organic hydride of Si, Ge or Sn.
[0186] More preferably, the electron donor component is an organic
hydride compound of Si, Ge or Sn.
[0187] Preferred organic hydrides of Si, Ge or Sn have the
following formula (XIV):
L*-H (XIV),
wherein L* is a moiety of the following formula (XV)
R.sup.aR.sup.bR.sup.cX*-- (XV).
[0188] In formula (XV), X* represents Si, Ge, or Sn, R.sup.a
represents a hydrogen atom, an organic moiety or a different moiety
L*, and R.sup.b and R.sup.c, which are independent from each other,
represent an organic moiety.
[0189] The organic metal hydride of formula (XIV) may react as a
hydrogen donating agent in a photoexcitation complex with the
alpha-diketone sensitizer. Accordingly, when an alpha-diketone
absorbs visible light and forms an exciplex with the organic metal
hydride of formula (XIV), a hydrogen transfer may take place from
the organic metal hydride to the alpha-diketone compound, whereby
the organic metal hydride of formula (XIV) is transformed into a
radical specifies capable of facilitating the polymerization
reaction.
[0190] In formula (XV), X* represents Si, Ge, or Sn. Preferably, X*
represents Si or Ge. More preferably, X* is Ge. According to a
specific embodiment, compound of formula (XIV) is a silane
compound. According to a further specific embodiment, compound of
formula (XIV) is a germane compound.
[0191] In formula (XV), R.sup.a may be a hydrogen atom, an organic
moiety or a different moiety L. When R.sup.a is a hydrogen atom,
then the compound of formula (XIV) contains two metal hydride bonds
(X*--H). In case R.sup.a is a hydrogen atom, the X* is Si.
[0192] When R.sup.a is an organic moiety, R.sup.a is preferably an
aromatic, an aliphatic or an alicyclic group. An aromatic group may
be a phenyl group. The phenyl group may be substituted by one or
more straight chain or branched alkyl groups having 1 to 6 carbon
atoms, alicyclic groups having 3 to 6 carbon atoms, halogen atoms,
hydroxyl groups, or amino groups. The aliphatic group may be a
straight chain or branched alkyl groups having 1 to 6 carbon atoms
which may be substituted by one or more aromatic groups, alicyclic
groups having 3 to 6 carbon atoms, halogen atoms, hydroxyl groups
or amino groups. An alicyclic group may be a group having 3 to 6
carbon atoms which may be substituted by one or more aromatic
groups, aliphatic groups, halogen atoms, hydroxyl groups or amino
groups.
[0193] When R.sup.a is a different moiety L*, the compound of
formula (XIV) of the formula (XIV) contains a metal-metal bond. In
case two moieties L* are present, then each X*, R.sup.a, R.sup.b
and R.sup.c may be the same or different and independently has the
meaning as defined by the present invention.
[0194] R.sup.b and R.sup.c which are independent from each other,
represent an organic moiety. An organic group may be an aromatic,
an aliphatic or an alicyclic group. An aromatic group may be a
phenyl group. The phenyl group may be substituted by one or more
straight chain or branched alkyl groups having 1 to 6 carbon atoms,
alicyclic groups having 3 to 6 carbon atoms, halogen atoms,
hydroxyl groups, or amino groups. The aliphatic group may be a
straight chain or branched alkyl groups having 1 to 6 carbon atoms
which may be substituted by one or more aromatic groups, alicyclic
groups having 3 to 6 carbon atoms, halogen atoms, hydroxyl groups
or amino groups. An alicyclic group may be a group having 3 to 6
carbon atoms which may be substituted by one or more aromatic
groups, aliphatic groups, halogen atoms, hydroxyl groups or amino
groups.
[0195] According to a preferred embodiment, R.sup.a, R.sup.b, and
R.sup.c in the compound of formula (XIV) are the same and represent
an aliphatic, an aromatic or an alicyclic hydrocarbon group.
[0196] According to a preferred embodiment, the compound of formula
(XIV) is a compound of the following formula:
##STR00016##
[0197] According to a preferred embodiment, the dental composition
contains the compound of formula (XIV) in an amount from 0.05 to 5
percent by weight based on the total weight of the composition.
[0198] Coinitiator components are preferably selected from iodonium
salts, sulfonium salts, phosphonium salts, amine compounds and
tertiary aromatic phosphine compounds.
[0199] Preferred iodonium, sulfonium or phosphonium salts
respectively have a cation selected from: [0200] (1) an iodonium
ion of the following formula (XVI):
[0200] R.sup.15--I.sup.+--R.sup.16 (XVI) [0201] wherein [0202]
R.sup.15 and R.sup.16 which are independent from each other
represent an organic moiety; [0203] (2) a sulfonium ion of the
following formula (XVII):
[0203] R.sup.17R.sup.18R.sup.19S.sup.+ (XVII) [0204] wherein [0205]
R.sup.17, R.sup.18 and R.sup.19 which are independent from each
other, represent an organic moiety, and optionally any two of
R.sup.5, R.sup.6 and R.sup.7 form a cyclic structure together with
the sulfur atom to which they are bound; [0206] (3) a phosphonium
ion of the following formula (XVIII):
[0206] R.sup.20R.sup.21R.sup.22P.sup.+ (XVIII) [0207] wherein
[0208] R.sup.20, R.sup.21 and R.sup.22 which are independent from
each other, represent an organic moiety.
[0209] Salts having a cation selected from formulae (XVI), (XVII)
and (XVIII) represent particularly efficient iodonium, sulfonium or
phosphonium salts and significantly improve the polymerization
performance of the photoinitiator system.
[0210] Preferably, R.sup.15 and R.sup.16 of the iodonium ion of
formula (XVI), R.sup.17, R.sup.18 and R.sup.19 of the sulfonium ion
of (XVII), and R.sup.29, R.sup.21 and R.sup.22 of the phosphonium
ion of formula (XVIII) are respectively selected from an aromatic,
an aliphatic or an alicyclic group. An aromatic group may be a
phenyl group. The phenyl group may be substituted by one or more
straight chain or branched alkyl groups having 1 to 6 carbon atoms,
straight chain or branched alkoxy groups having 1 to 6 carbon
atoms, aromatic groups such as aryl groups or aryloxy groups,
alicyclic groups having 3 to 6 carbon atoms, halogen atoms,
hydroxyl groups, or amino groups. The aliphatic group may be a
straight chain or branched alkyl groups having 1 to 6 carbon atoms
which may be substituted by one or more aromatic groups, alicyclic
groups having 3 to 6 carbon atoms, halogen atoms, hydroxyl groups
or amino groups. An alicyclic group may be a group having 3 to 6
carbon atoms which may be substituted by one or more aromatic
groups, aliphatic groups, halogen atoms, hydroxyl groups or amino
groups.
[0211] More preferably, R.sup.15 and R.sup.16 of the iodonium ion
of formula (XVI) and R.sup.17, R.sup.18 and R.sup.19 of the
sulfonium ion of (XVII) are respectively selected from a phenyl
group which may be substituted with 1 to 3 substituents selected
from halogen atoms, a cyano group, a hydroxy group, an amino group,
C.sub.1-6 alkyl groups and C.sub.1-6 alkoxy groups.
[0212] According to a preferred embodiment, the iodonium ion of
formula (XVI) is a diaryl iodonium ion. Examples of useful diaryl
iodonium ions include (4-methylphenyl)[4-(2-methylpropyl) phenyl]
iodonium, diphenyliodonium tetrafluoroborate,
di(4-methylphenyl)iodonium, phenyl-4-methylphenyliodonium,
di(4-heptylphenyl)iodonium, di(3-nitrophenyl)iodonium,
di(4-chlorophenyl)iodonium, di(naphthyl)iodonium,
di(4-trifluoromethylphenyl)iodonium, diphenyliodonium,
di(4-methylphenyl)iodonium; diphenyliodonium,
di(4-phenoxyphenyl)iodonium, phenyl-2-thienyliodonium,
3,5-dimethylpyrazoly-4-phenyliodonium, diphenyliodonium,
2,2'-diphenyliodonium, di(2,4-dichlorophenyl)iodonium,
di(4-bromophenyl)iodonium, di(4-methoxyphenyl)iodonium,
di(3-carboxyphenyl)iodonium, di(3-methoxycarbonylphenyl)iodonium,
di(3-methylsulfonylphenyl)iodonium, di(4-acetamidophenyl)iodonium,
di(2-benzothienyl)iodonium, and diphenyliodonium.
[0213] More preferably aromatic iodonium ions of formula (XVI) are
selected from the group consisting of diaryliodonium,
(4-methylphenyl)[4-(2-methylpropyl) phenyl] iodonium,
4-octyloxyphenyl phenyliodonium, and 4-(1-methylethyl)phenyl
4-methylphenyliodonium. Most preferably, the aromatic iodonium ion
of formula (XVI) is diphenyliodonium or
(4-methylphenyl)[4-(2-methylpropyl)phenyl]iodonium.
[0214] A preferred sulfonium ion of formula (XVII) is
S-(phenyl)thianthrenium of the following formula:
##STR00017##
[0215] Preferably, in a phosphonium ion of formula (XVIII),
R.sup.20, R.sup.21 and R.sup.22 independently from each other
represent an aliphatic group, more preferably a straight chain or
branched alkyl group having 1 to 6 carbon atoms which may be
substituted by one or more aromatic groups, alicyclic groups having
3 to 6 carbon atoms, halogen atoms, hydroxyl groups or amino
groups. More preferably, in a phosphonium ion of formula (XVIII),
R.sup.20, R.sup.21 and R.sup.22 independently from each other
represent a straight chain or branched alkyl group having 1 to 4
carbon atoms which may be substituted by one or more halogen atoms,
hydroxyl groups or amino groups.
[0216] A particularly preferred phosphonium ion of formula (XVIII)
is tetrakis-(hydroxymethyl)-phosphonium (THP).
[0217] In the iodonium, sulfonium or phosphonium salts having a
cation of formula (XVI), (XVII) or (XVIII), the anion may be
selected from hexafluoroantimonate, trifluoromethylsulfate,
hexafluorophosphate, tetrafluoroborate, hexafluoroarsenate, and
tetraphenylborate.
[0218] Preferred amine compounds are tertiary amine compounds, more
preferably tertiary amine compounds selected from the group
consisting of triethanolamine, 4-N,N-dimethylaminobenzonitrile,
methyl N,N-dimethylaminobenzoate, ethyl N,N-dimethylaminobenzoate,
N,N-dimethylaminoethyl methacrylate and isoamyl
4-N,N-dimethylaminobenzoate, N,N-dimethylaniline,
N,N-dimethyltoluidine, N,N-diethanoltoluidine,
dimethylaminoanisole, 1 or 2-d imethylaminonaphthalene. Most
preferably, the tertiary amine compound is selected from the group
consisting of triethanolamine, methyl 4-N,N-dimethylaminobenzoate,
ethyl 4-N,N-dimethylaminobenzoate, 4-N,N-dimethylaminoethyl
methacrylate and isoamyl 4-N,N-dimethylaminobenzoate.
[0219] Preferred aromatic tertiary phosphine compounds have the
following formula (XIX):
Z.sup.P--R.sup.P (XIX) [0220] wherein [0221] Z.sup.P is a group of
the following formula (XX)
[0221] R*(Ar.sup.P)P-- (XX) [0222] wherein [0223] R* represents a
substituted or unsubstituted hydrocarbyl group; [0224] Ar.sup.P
represents a substituted or unsubstituted aryl or heteroaryl group;
[0225] R.sup.P is an aryl group, which may be substituted by one or
more groups selected from a hydroxyl group, an amino group, a
--NR.sup.aR.sup.b group (wherein R.sup.a and R.sup.b, which may be
the same or different, are selected from C.sub.1-6 alkyl groups), a
carboxyl group, and a group having a polymerizable double bond;
wherein the group R* and Ar.sup.P may be substituted by one or more
groups selected from a hydroxyl group, an oxo group, a
--NR.sub.aR.sub.b group (wherein R.sub.a and R.sub.b, which may be
the same or different, are selected from a hydrogen atom and
C.sub.1-6 alkyl groups), a carboxyl group, and a group having a
polymerizable double bond, and L.sup.P may be substituted by one or
more groups selected from a hydroxyl group, an oxo group, a
--NR.sub.aR.sub.b group (wherein R.sub.a and R.sub.b, which may be
the same or different, are selected from a hydrogen atom and
C.sub.1-6 alkyl groups), a carboxyl group, and a group having a
polymerizable double bond.
[0226] In formula (XIX), for R*, the monovalent hydrocarbyl group
may be an alkyl group, a cycloalkyl group, a cycloalkylalkyl group,
an arylalkyl group or an aryl group.
[0227] Ar.sup.P represents a substituted or unsubstituted aryl or
heteroaryl group. An aryl group may be selected from a phenyl
group, a naphtyl group, a tolyl group, a xylyl group, and a styryl
group. A heteroaryl group may be a pyridyl group.
[0228] L.sup.P is a substituted or unsubstituted divalent
hydrocarbyl group which may contain a linkage selected from an
ether linkage, a thioether linkage, an ester linkage, an amide
linkage, and a urethane linkage. For L.sup.P, the divalent
hydrocarbyl group may be an alkyldiyl group, a cycloalkyldiyl
group, a cycloalkylalkyl-diyl group, an arylalkyl-diyl group or an
aryldiyl group. In a cycloalkylalkyl-diyl, one valency may be
bonded to each of the cycloalkyl moiety or the alkyl moiety, or
both valencies may be bonded to either the cycloalkyl moiety or the
alkyl moiety. In a arylalkyl-diyl group, each of the aryl moiety or
the alkyl moiety may be monovalent respectively, or either the aryl
moiety or the alkyl moiety is divalent, while the other moiety is
nonvalent. In a cycloalkylalkyl-diyl, each of the cycloalkyl moiety
or the alkyl moiety may be monovalent respectively, or either the
cycloalkyl moiety or the alkyl moiety is divalent, while the other
moiety is nonvalent.
[0229] The following definitions apply both for the monovalent and
the divalent hydrocarbyl group, therefore, for the definition of
the divalent hydrocarbyl group, the suffixes "diyl" and "-diyl" are
bracketed.
[0230] An alkyl(diyl) group may be straight-chain or branched
C.sub.1-20 alkyl(diyl) group, typically a C.sub.1-8 alkyl(diyl)
group. Examples for a C.sub.1-6 alkyl(diyl) group can include
linear or branched alkyl(diyl) groups having 1 to 6 carbon atoms,
preferably 1 to 4 carbon atoms, for example, methyl(diyl),
ethyl(diyl), n-propyl(diyl), isopropyl(diyl), n-butyl(diyl),
isobutyl(diyl), sec-butyl(diyl), tert-butyl(diyl), n-pentyl(diyl),
isopentyl(diyl) and n-hexyl(diyl).
[0231] A cycloalkyl(diyl) group may be a C.sub.3-20
cycloalkyl(diyl) group. Examples of the cycloalkyl(diyl) group can
include those having 3 to 14 carbon atoms, for example,
cyclopropyl(diyl), cyclobutyl(diyl), cyclopentyl(diyl) and
cyclohexyl(diyl). A cycloalkylalkyl(diyl) group can include those
having 4 to 20 carbon atoms.
[0232] A cycloalkylalkyl(-diyl) group can include a combination of
a linear or branched alkyl(diyl) group having 1 to 6 carbon atoms
and a cycloalkyl(diyl) group having 3 to 14 carbon atoms. Examples
of the cycloalkylalkyl(-diyl) group can for example, include
methylcyclopropyl(-diyl) methylcyclobutyl(-diyl),
methylcyclopentyl(-diyl), methylcyclohexyl(-diyl),
ethylcyclopropyl(-diyl), ethylcyclobutyl(-diyl),
ethylcyclopentyl(-diyl), ethylcyclohexyl(-diyl),
propylcyclopropyl(-diyl), propylcyclobutyl(-diyl),
propylcyclopentyl(-diyl), propylcyclohexyl(-diyl).
[0233] An arylalkyl(-diyl) group may be a C.sub.7-20
arylalkyl(-diyl) group, typically a combination of a linear or
branched alkyl(diyl) group having 1 to 6 carbon atoms and an
aryl(-diyl) group having 6 to 10 carbon atoms. Specific examples of
an arylalkyl(-diyl) group are a benzyl(-diyl) group or a
phenylethyl(-diyl) group.
[0234] An aryl(diyl) group can include aryl(diyl) groups having 6
to 10 carbon atoms. Examples of the aryl(diyl) group are
phenyl(diyl) and naphtyl(diyl). Aryl(diyl) groups may contain 1 to
3 substituents. Examples of such substituents can include halogen
atoms, a cyano group, a hydroxy group, an amino group, C.sub.1-6
alkyl groups and C.sub.1-6 alkoxy groups. Here, illustrative of the
halogen atoms can be fluorine, chlorine, bromine and iodine. The
C.sub.1-4 alkyl(diyl) groups are, for example, methyl(diyl),
ethyl(diyl), n-propyl(diyl), isopropyl(diyl) and n-butyl(diyl).
Illustrative of the C.sub.1-4 alkoxy(diyl) groups are, for example,
methoxy(diyl), ethoxy(diyl) and propoxy(diyl). The alkyl(diyl)
moieties in these substituents may be linear, branched or
cyclic.
[0235] Preferably, the hydrocarbyl group is an aryl(diyl) group
selected from a phenyl(diyl) group and a naphthyl(diyl) group,
which groups may optionally be substituted by one to three groups
selected from halogen atoms, a cyano group, an amino group, a
hydroxy group, C.sub.1-6 alkyl groups and C1-6 alkoxy groups, or
wherein the hydrocarbyl group is a non-aromatic hydrocarbyl group
selected from a straight chain or branched alkyl group, a straight
chain or branched alkenyl group, or a straight chain or branched
alkynyl group.
[0236] The C.sub.1-8 alkyl(diyl) group and the C.sub.3-14
cycloalkyl(diyl) group may optionally be substituted by one or more
members of the group selected from a C.sub.1-4 alkyl group,
C.sub.1-4 alkoxy group, a phenyl group, and a hydroxy group.
Examples for a C.sub.1-4 alkyl group can include linear or branched
alkyl groups having 1 to 4 carbon atoms, for example, methyl,
ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl,
tert-butyl. Examples for an C.sub.1-4 alkoxy group can include
linear or branched alkoxy groups having 1 to 4 carbon atoms, for
example, methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy,
isobutoxy, sec-butoxy, and tert-butoxy.
[0237] Moreover, in formula (XIX), any of the hydrocarbyl group may
be substituted by one or more groups selected from halogen atoms, a
cyano group, an amino group or a hydroxy group. Accordingly, in the
hydrocarbyl groups some or all hydrogen atoms are replaced by
halogen atoms (e.g., fluoro, bromo, chloro), for example,
halo-substituted alkyl groups such as chloromethyl, chloropropyl,
bromoethyl and trifluoropropyl, and cyanoethyl.
[0238] In case the hydrocarbyl group contains an alkyl(diyl) chain,
one or more carbon atoms in the alkyl(diyl) chain may be replaced
by an oxygen atom, a sulfur atom, an amide group, an ester group,
or a urethane group. In case the hydrocarbyl group is an alkyl
group having more than one carbon atom, the alkyl group contains an
alkylene. Accordingly, in case the hydrocarbyl group is an n-hexyl
group, any of the carbon atoms of the alkylene chain excluding the
terminal methyl group may be replaced by an oxygen atom, a sulfur
atom, an amide group, an ester group, a urethane group or an NH
group. Therefore, the following groups may be given as specific
examples in case of one or more oxygen atoms:
##STR00018##
[0239] In formula (XIX), group R* and/or Ar.sup.P as well as
R.sup.P and/or may be substituted with a polymerizable double bond,
preferably a carbon-carbon double bond. Examples of polymerizable
carbon-carbon double bonds include vinyl, conjugated vinyl, allyl,
acryl, methacryl and styryl. Preferably, the polymerizable double
bond is selected from the group consisting of methacryl, acryl and
styryl. More preferably, the double bond is styryl.
[0240] Preferably, R* and Ar.sup.P independently are aromatic
hydrocarbyl groups selected from a phenyl group, a naphtyl group, a
tolyl group, a xylyl group, and a styryl group.
[0241] As regards R.sup.P, this moiety is an aryl group, which may
be substituted by one or more groups selected from a hydroxyl
group, an amino group, a --NR.sub.aR.sub.b group (wherein R.sub.a
and R.sub.b, which may be the same or different, are selected from
C.sub.1-6alkyl groups), a carboxyl group, and a group having a
polymerizable double bond. According to a preferred embodiment,
R.sup.P is an aryl group substituted by one or more groups selected
from a hydroxyl group, an amino group, a --NR.sub.aR.sub.b group
(wherein R.sub.a and R.sub.b, which may be the same or different,
are selected from C.sub.1-6 alkyl groups), a carboxyl group, and a
group having a polymerizable double bond. More preferably, R.sup.P
is a phenyl group substituted by one or two groups selected from a
hydroxyl group, an amino group, a --NR.sub.aR.sub.b group (wherein
R.sub.a and R.sub.b, which may be the same or different, are
selected from C.sub.1-6 alkyl groups), a carboxyl group, and a
group having a polymerizable double bond.
[0242] Even more preferably, the aromatic phosphine compound is a
compound of formula (XIX) wherein Z.sup.P is a group of the
following formula:
##STR00019##
[0243] Specific examples for a compound of formula (XIX) include
triphenyl phosphine (TPP), 4-(diphenylphosphino)styrene (DPPS),
4-(diphenylphosphino)benzoic acid, 4-(diphenylphosphino) benzoic
acid, 3-(diphenylphophonino)propionic acid, (4-(diphenylphosphino)
N,N''-dimethylaniline, 2,2''-bis(diphenylphosphino)benzophenone
(BDPPEP), bis[2-(di-phenylphosphino)phenyl]ether (BDPPE),
(4-Hydroxyphenyl)diphenylphosphine, allyldiphenylphosphine.
Preferably, the compound of formula (XIX) is triphenyl phosphine
(TPP) or 4-(diphenylphosphino)styrene (DPPS), more preferably
4-(diphenylphosphino)styrene (DPPS).
[0244] From the above listed aromatic tertiary compounds of formula
(XIX), 4-(diphenylphosphino)styrene (DPPS) is particularly
preferred, since this compound provides for particularly improved
photo-bleaching results compared to the already advantageous
results obtained with triphenyl phosphine (TPP).
[0245] A compound of the formula (XIX) may be a known compound
which is commercially available or may be prepared according to
published procedures, as described for example in WO/2016/156363
A1.
[0246] Furthermore, the photoinitiator system may comprise a
sensitizer component selected from a Norrish type I or II
sensitizer as described above. The sensitizer component represents
an additional photosensitizer other than the photosensitizer (b1)
of the photoinitiator system (b).
[0247] The Reactive Particulate Filler (c)
[0248] Optionally, the dental composition according to the present
invention comprises (c) a reactive particulate filler. The dental
composition may comprise one or a mixture of two or more reactive
particulate fillers (c).
[0249] Any granular component being reactive with a polyacidic
polymer in a cement reaction may be used as the reactive
particulate filler (c), that is, any alkaline granular compound
suitable for a dental composition.
[0250] The term "cement reaction" as used herein means an acid-base
reaction between the reactive particulate filler (c) and a
polyacidic polymer in the presence of water. Water provides a
medium needed for the ionic acid-base reaction to take place
between the reactive particulate filler (c) and a polyacidic
polymer.
[0251] Preferably, the reactive particulate filler (c) is one or a
mixture of two or more metal oxides, most preferably a glass, i.e.
an amorphous solid mixture of metal oxides.
[0252] The reactive particulate filler (c) in the form of a glass
is obtainable by transforming a solid mixture of metal oxides by a
thermal melt process into a glass followed by milling, which glass
is capable of reacting with a polyacidic polymer in a cement
reaction
[0253] Any conventional reactive dental glass may be used as
reactive particulate filler (c). Specific examples of particulate
reactive glasses are selected from calcium alumino silicate glass,
calcium alumino fluorosilicate glass, calcium
aluminumfluoroborosilicate glass, strontium aluminosilicate glass,
strontium aluminofluorosilicate glass, strontium
aluminofluoroborosilicate glass, or ion-leachable glasses, e.g. as
described in U.S. Pat. Nos. 3,655,605, 3,814,717, 4,143,018,
4,209,434, 4,360,605 and 4,376,835.
[0254] Alternatively or additionally, reactive metal oxides such as
zinc oxide and/or magnesium oxide may be used in glass and/or
crystalline form as reactive particulate filler (c).
[0255] Preferably, the reactive particulate filler (c) is a glass
comprising: [0256] 1) 20 to 45% by weight of silica, [0257] 2) 20
to 40% by weight of alumina, [0258] 3) 20 to 40% by weight of
strontium oxide, [0259] 4) 1 to 10% by weight of P.sub.2O.sub.5,
and [0260] 5) 3 to 25% by weight of fluoride.
[0261] The present dental composition preferably comprises 20 to 90
percent by weight of the reactive particulate filler (c), more
preferably 30 to 85 percent by weight, most preferably 20 to 80
percent by weight based on the total weight of the composition.
[0262] The reactive particulate filler (c) usually has an average
particle size of from 0.1 to 100 .mu.m, preferably of from 1 to 40
.mu.m as measured, for example, by electron microscopy or by using
a conventional laser diffraction particle sizing method as embodied
by a MALVERN Mastersizer S or MALVERN Mastersizer 2000
apparatus.
[0263] The reactive particulate filler (c) may have a unimodal or
multimodal (e.g., bimodal) particle size distribution, wherein a
multimodal reactive particulate filler (c) represents a mixture of
two or more particulate fractions having different average particle
sizes.
[0264] The reactive particulate filler (c) may be an agglomerated
reactive particulate filler which is obtainable by agglomerating a
reactive particulate filler in the presence of a modified polyacid
and/or polymerizable resin such as (meth)acryloyl monomers. The
particle size of the agglomerated reactive particulate filler (c)
may be adjusted by suitable size-reduction processes such as
milling.
[0265] The reactive particulate filler (c) may be surface modified
by a surface modifying agent. Preferably, the surface modifying
agent is a silane. A silane provides a suitable hydrophobicity to
the reactive particulate filler (c), which allows for an
advantageous, homogeneous admixture with organic components of the
dental composition. The reactive particulate filler (c) may have
silane coupling agent(s) on its surface, for example in the form of
a coating at least partly, and preferably fully covering the
surface of the reactive particulate filler (c).
[0266] The Polyacidic Polymer (d)
[0267] Optionally, the dental composition according to the present
invention comprises (d) a polyacidic polymer which is reactive with
the reactive particulate filler in a cement reaction, which is
termed as "polyacidic polymer (d)" hereinafter. The dental
composition may comprise one or a mixture of two or more polyacidic
polymers (d).
[0268] Preferably, in the polyacidic polymer (d), the plurality of
acidic groups comprises acidic groups selected from a group
(C=Het.sub.1)-Het.sub.2H, wherein Het, is an oxygen atom or a
sulfur atom, and Het.sub.2 is an oxygen atom or a sulfur atom. That
is, the acidic groups are preferably selected from carboxylic acid
group ((C.dbd.O)--OH), (C.dbd.S)--SH, (C.dbd.O)--SH and
(C.dbd.S)--OH. The most preferred acidic group is the carboxylic
acid group ((C.dbd.O)--OH).
[0269] The acidic groups of the polyacidic polymer (d) can react
with the reactive particulate filler (a) to form a glass ionomer
cement which can be used as a dental material.
[0270] Preferably, the polyacidic polymer (d) is water-soluble. The
term "water-soluble" means that at least 0.1 g, preferably 0.5 g of
the polyacidic polymer (d) dissolves in 100 g of water at
20.degree. C.
[0271] Furthermore, it is preferred that the polyacidic polymer (d)
is hydrolysis-stable. "Hydrolysis-stable" means that the polyacidic
polymer (d) is stable to hydrolysis in an acidic medium, such as in
a dental composition. Specifically, the polyacidic polymer (d)
preferably does not contain groups such as ester groups which
hydrolyze in aqueous media at pH 3 at room temperature within one
month.
[0272] In general, the polyacidic polymer (d) may for example be
prepared based by polymerizing acrylic acid or a mixture comprising
acrylic acid and one or a mixture of polymerizable monomers having
a polymerizable double bond and optionally a carboxylic acid
group.
[0273] According to a particularly preferred embodiment, the
polyacidic polymer (d) has repeating units of the following formula
(XXI)
##STR00020##
[0274] In formula (XXI), A.sup.o, which may be the same or
different, independently is selected from a group of the following
formulae (XXIa) to (XXIf):
##STR00021##
[0275] Furthermore, in formula (XXI), k, l, m, n and o are
independently integers of at least 0, k+l+m+n+o is at least 2, and
at least one of k, l, n, and o is at least 1.
[0276] Preferably, the polyacidic polymer (d) having repeating
units of the following formula (XXI) has a weight average molecular
weight of 1 to 300 kDa, more preferably 5 to 250 kDa, most
preferably 10 to 200 kDa.
[0277] The polyacidic polymer (d) having repeating units of the
following formula (XXI) may be prepared based by polymerizing
acrylic acid or a mixture comprising acrylic acid.
[0278] A mixture comprising acrylic acid may further comprise one
or more unsaturated monocarboxylic acids or unsaturated
dicarboxylic acids or an anhydride of the unsaturated dicarboxylic
acids. Specific examples include itaconic acid, maleic acid,
methacrylic acid, 2-chloroacrylic acid, 2-cyanoacrylic acid,
aconitic acid, mesaconic acid, fumaric acid, glutaconic acid,
citraconic acid, utraconic acid, and an anhydride of the
unsaturated dicarboxylic acids. Itaconic acid and maleic acid are
preferred.
[0279] Furthermore, a mixture comprising acrylic acid may further
comprise copolymerizable monomers which do not have a carboxylic
acid functionality or an anhydride thereof, whereby it is
preferable that the proportion of the unsaturated carboxylic acid
units is 50% by mol or more of the entire structural units.
Preferably, the polyacidic polymer (d) having repeating units of
the following formula (XXI) contains from 50 to 100 mole percent of
acrylic acid repeating units.
[0280] The copolymerizable monomer is preferably an ethylenically
unsaturated polymerizable monomer, and the copolymerizable monomer
includes, for example, styrene, acrylamide, acrylonitrile, methyl
methacrylate, vinyl chloride, allyl chloride, vinyl acetate,
1,1,6-trimethylhexamethylene dimethacrylate ester.
[0281] Among the polyacidic polymers (d) having repeating units of
the following formula (XXI), homopolymers of acrylic acid and
copolymers of acrylic acid and itaconic acid anhydride are
preferred. According to a preferred embodiment, the polyacidic
polymers (d) having repeating units of the following formula (XXI)
is polyacrylic acid or a copolymer of acrylic acid and itaconic
anhydride.
[0282] Alternatively or additionally to the polyacidic polymer (d)
having repeating units of the following formula (XXI), a polyacidic
polymer (d) may be used having repeating units of the following
formula (XXII)
##STR00022##
[0283] In formula (XXII), R is an organic group having one or more
polymerizable double bond, and A.sup.o as well as k, l, m, n and o
are defined as above for formula (XXI).
[0284] Preferably, the polyacidic polymer (d) having repeating
units of the following formula (XXII) is prepared by a process in
which the polyacidic polymer having repeating units of following
formula (XXI) as defined above is reacted with one or more
polymerizable compounds of the following formula (XXIII) in a
solvent:
R--X.sup.o (XXIII).
[0285] In formula (XXIII), X.sup.o is selected from an amino group
and an isocyanato group, and R is an organic group having one or
more polymerizable double bond, for preparing a polymerizable
linear polyacidic acrylic polymer having polymerizable pendant
groups linked to the acrylic polymer backbone by amide groups.
Preferably, X.sup.o is an amino group.
[0286] The reacting with polymerizable compounds of formula (XXIII)
serves to introduce one or more polymerizable moieties into the
polyacidic polymer having repeating units of the following formula
(XXI), which moieties can be post-polymerized to provide additional
covalent crosslinking, imparting additional strength to a cured
dental composition comprising the polymer.
[0287] According to the present invention, it is not required that
the carboxylic acid groups of the polymer are protected. Therefore,
the polymerizable polyacidic polymer (d) having repeating units of
the following formula (XXII) having polymerizable pendant groups
linked to the acrylic polymer backbone by amide groups can be used
as a polymer according to the present invention without further
treatment.
[0288] In an alternative embodiment, the carboxylic acid groups of
the polymer are protected. Any protective group for carboxylic acid
groups known in the art of organic chemistry may be used, as
described e.g. in P. G. M. Wuts and T. W. Greene, Greene's
Protective Groups in Organic Synthesis, 4th Edition, John Wiley and
Sons Inc., 2007. However, the carboxylic acid groups would have to
be deprotected before the polymer may be used in a cement reaction.
Therefore, the alternative embodiment is less preferred.
[0289] According to a preferred embodiment, R.sup.o in formula
(XXIII) is a moiety of the following formula (XXIV):
##STR00023##
[0290] In formula (XXIV), R.sup.23 represents a hydrogen atom, a
carboxylic acid group or a C.sub.1-3 alkyl group, R.sup.24
represents a hydrogen atom, a carboxylic acid group or a C.sub.1-3
alkyl group, and L.sup.o represents a divalent organic linker
group.
[0291] In formula (XXIV), L.sup.o is preferably a group
--Y.sup.oL'-, wherein Y.sup.o represents 0 or NH, and L.sup.o
represents a divalent organic group.
[0292] Preferably, a polymerizable compound of formula (XXIII) with
X being an amino group is reacted with the polyacidic polymer
having repeating units of formula (XXI) in which the carboxylic
acid groups are activated with a coupling agent prior to the
reaction with the polymerizable compounds of the formula (XXIII).
According to a preferred embodiment, the coupling agent is a
carbodiimide. Specifically, the carbodiimide may be selected from
N,N'-dicyclohexylcarbodiimide (DCC),
N-(3-Dimethylaminopropyl)-N'-ethylcarbonate (EDC), and
N,N'-diisopropylcarbodiimide (DIC).
[0293] In formula (XXIII), when X is an isocyanato group, addition
of a carboxylic acid to the isocyanate initially yields the mixed
acid anhydride, decarboxylation of which leads to the N-substituted
amide.
[0294] In the process for preparing polyacidic polymer having
repeating units of formula (XXII), preferably 0.02 to 0.5 eq. of
the one or more polymerizable compounds of the formula (XXIII) are
reacted based on the total number of carboxylic acid groups of the
polyacidic polymer having repeating units of formula (XXI).
[0295] The reaction conditions of the process are not particularly
limited. Accordingly, it is possible to carry out the reaction in
any suitable solvent or a suitable mixture of two or more solvents.
Preferably, a solvent may be selected from the group of
dimethylformamide (DMF), acetonitrile, carbon tetrachloride,
tetrahydrofurane (THF), and dioxane. More preferably,
dimethylformamide (DMF), acetonitrile, and/or carbon tetrachloride
are used.
[0296] The reaction temperature is not particularly limited.
Preferably, the reaction is carried out at a temperature of between
-10.degree. C. to the boiling point of the solvent. Preferably, the
reaction temperature is in the range of from 0.degree. C. to
100.degree. C. The reaction time is not particularly limited.
Preferably, the reaction time is in the range of from 10 minutes to
120 hours, more preferably 1 hour to 80 hours. The reaction between
the polyacidic polymer (d) having repeating units of the following
formula (XXI) and the one or more polymerizable compound of the
formula (XXIII) may preferably be carried out at a temperature of
from 20 to 100.degree. C. for 1 to 60 hours.
[0297] The reaction product of the process may be isolated by
precipitation and filtration. The product may be purified by
washing with a suitable solvent.
[0298] Most preferably, the polyacidic polymer (d) has repeating
units of the following formula
##STR00024##
[0299] In formula (XXII'), R is as defined above for formula
(XXII), k, l, m, n, and o are independently integers of at least 0,
k+l+m+n+o is at least 2; at least one of k, l, n, and at least 1,
and m is at least 1. Furthermore, A.sup.o, which may be the same or
different, independently represent a group selected from groups of
the following formula (XXII'c), (XXII'd), and (XXII'f):
##STR00025##
[0300] In formula (XXII'c) and (XXII'd) and (XXII'f), Z is COOH
CONHR', wherein at least one Z is COOH, and R' is as defined above
for formula (XXI).
[0301] Preferably, the polyacidic polymer having repeating units of
formula (IV') has a weight average molecular weight of 1.2 to 400
kDa, more preferably 6 to 350 kDa, most preferably 12 to 300
kDa.
[0302] When the polyacidic polymer (d) has a weight-average
molecular weight of less than 1 kDa, the strength of the cured
dental composition is lowered. On the other hand, when the
polyacidic polymer (d) has a weight-average molecular weight
exceeding a viscosity of 400 kDa, upon mixing and blending the
dental composition becomes harder, so that workability is lowered
in some cases. Therefore, the preferred weight-average molecular
weight of the polyacidic polymer (d) is from 1 to 300 kDa.
[0303] Further Optional Components.
[0304] The dental composition according to the present invention
may, besides of optional components reactive particulate filler (c)
and polyacidic polymer (d), comprise additional optional
components.
[0305] The dental composition according to the present invention
may contain further components such as a redox initiator, further
fillers besides of reactive particulate filler (a), components
improving radio-opacity, solvents, free radical scavengers such as
4-methoxyphenol, polymerization inhibitors, surfactants (such as to
enhance solubility of an inhibitor e. g., polyoxyethylene),
coupling agents to enhance reactivity of fillers e.g.
3-(trimethoxysilyl) propyl methacrylate, and rheology
modifiers.
[0306] Preferably, the dental composition contains a redox
initiator.
[0307] The term "redox initiator" means a combination of an
oxidizing agent and a reducing agent, and optionally a catalyst
such as a metal salt. The redox initiator provides a redox reaction
in which radicals are formed. These radicals initiate
polymerisation of a radically polymerizable compound. Typically, a
redox initiator system is activated by bringing the redox initiator
system in contact with water and/or an organic solvent providing
for at least partial dissolution of the oxidising agent and the
reducing agent. The optional catalyst may be added to accelerate
the redox reaction and thus the polymerization of the compound
having a polymerizable double bond (a).
[0308] A mixture of the photoinitiator system (b) and a redox
initiator is a "dual cure initiator system".
[0309] A suitable redox initiator system comprises reducing and
oxidizing agents, which produce free-radicals capable of initiating
polymerization of the polymerizable double bonds of the compound
having a polymerizable double bond (a), independent from the
presence of light. The reducing and oxidizing agents are selected
such that the dental composition is sufficiently storage-stable and
free of undesirable colorization to permit storage and use under
typical dental conditions. Moreover, the reducing and oxidizing
agents are selected so that the dual cure initiators system is
sufficiently miscible with the resin system to permit dissolution
of the redox initiator system in the composition.
[0310] Useful reducing agents include ascorbic acid, ascorbic acid
derivatives, and metal complexed ascorbic acid compounds as
described in U.S. Pat. No. 5,501,727; amines, namely tertiary
amines, preferably tertiary aromatic amines such as 4-tert-butyl
dimethylaniline; aromatic sulfinate salts such as
p-toluenesulfinate salts and benzenesulfinate salts, most
preferably sodium para-toluenesulfinate; thioureas, such as
1-ethyl-2-thiourea, tetraethyl thiourea, tetramethyl thiourea,
1,1-dibutyl thiourea, and 1,3-dibutyl thiourea; and mixtures
thereof.
[0311] Other secondary reducing agents may include cobalt (Ill)
chloride, ferrous chloride, ferrous sulfate, hydrazine,
hydroxylamine, salts of a dithionite or sulfite anion, and mixtures
thereof.
[0312] Suitable oxidizing agents include persulfuric acid and salts
thereof, such as ammonium, sodium, potassium, cesium, and alkyl
ammonium salts, preferably inorganic peroxodisulfate salts, most
preferably potassium peroxodisulphate. Additional oxidizing agents
include peroxides such as benzoyl peroxides, hydroperoxides such as
cumyl hydroperoxide, t-butyl hydroperoxide, and amyl hydroperoxide,
as well as salts of transition metals such as cobalt (Ill) chloride
and ferric chloride, cerium (IV) sulfate, perboric acid and salts
thereof, permanganic acid and salts thereof, perphosphoric acid and
salts thereof, and mixtures thereof. One or more different
oxidizing agents or one or more different reducing agent may be
used in the initiator system. Small quantities of transition metal
compounds may also be added to accelerate the rate of redox cure.
The reducing and oxidizing agents are present in amounts sufficient
to permit an adequate free-radical reaction rate.
[0313] The reducing or oxidizing agents may be microencapsulated
for enhancing shelf stability of the composition, and if necessary
permitting packaging the reducing and oxidizing agents together
(U.S. Pat. No. 5,154,762). Appropriate selection of an encapsulant
may allow combination of the oxidizing and reducing agents and even
of an acid-functional component and optional filler in a
storage-stable state. Moreover, appropriate selection of a
water-insoluble encapsulant allows combination of the reducing and
oxidizing agents with the particulate reactive glass and water in a
storage-stable state.
[0314] A particularly preferred redox initiator contains (i) an
inorganic peroxodisulphate salt, (ii) an aromatic amine, and (iii)
an aromatic or non-aromatic sulfinate salt. For the particularly
preferred redox initiator, it is preferred that the inorganic
peroxodisulphate salt is potassium peroxodisulphate; and/or the
aromatic amine is tert.-butyl-N,N-dimethylaniline
(4-tert.-butyl-N,N-dimethylaniline); and/or the aromatic sulfinate
salt is sodium para-toluenesulfinate. Most preferably, the redox
initiator contains (i') potassium peroxodisulphate, (ii')
4-tert.-butyl-N,N-dimethylaniline, and (iii') sodium
para-toluenesulfinate.
[0315] Preferably, a dual cure initiator system contains the
photoinitiator system with the covalently bonded coinitiator
compound having formula (I) or (II), and the redox initiator
contains (i) an inorganic peroxodisulphate salt, (ii) an aromatic
amine, and (iii) an aromatic or non-aromatic sulfinate salt, more
preferably the redox initiator contains (i') potassium
peroxodisulphate, (ii') tert.-butyl-N,N-dimethylaniline, and (iii')
sodium para-toluenesulfinate.
[0316] Further filler(s) besides of the reactive particulate filler
(c) may for example be selected from inert glass(es), fluoride
releasing glass(es), granulated prepolymerized fillers, ground
prepolymerized fillers and filler aggregates.
[0317] The term "inert glass(es)" refers to a glass which is not
capable of reacting with a polymer containing acidic groups in a
cement reaction. Inert glasses are for example described in the
Journal of Dental Research June 1979, pages 1607-1619, or more
recently in U.S. Pat. Nos. 4,814,362, 5,318,929, 5,360,770, and
application US 2004/0079258 A1. Specifically, from US 2004/0079258
A1, inert glasses are known in which strongly basic oxides such as
CaO, BaO, SrO, MgO, ZnO, Na.sub.2O, K.sub.2O, Li.sub.2O etc. are
replaced with weakly basic oxides such as those in the Scandium or
Lanthanide series.
[0318] The term "fluoride releasing glass(es)" refers to a glass
capable to of releasing fluoride. Fluoride releasing capability may
be provided by adding to a mixture of oxides for forming a glass
inorganic particles containing fluoride with the proviso that the
glass has fluoride releasability, preferably sustained fluoride
releasability. Such inorganic particles may be selected from the
group consisting of sodium fluoride, strontium fluoride, lanthanum
fluoride, ytterbium fluoride, yttrium fluoride, and
calcium-containing fluoroaluminosilicate glasses.
[0319] Components improving radio-opacity may for example be
selected from CaWO.sub.4, ZrO.sub.2 and YF.sub.3.
[0320] Suitable solvents may be selected from water, alcohols such
as methanol, ethanol, propanol (n-, i-), butanol (n-, iso-,
tert.-), and ketones such as acetone.
[0321] The dental composition of the present invention may
preferably comprise a solvent in an amount of 5 to 75 percent by
weight based on the total weight of the dental composition.
[0322] Preferably, in the dental composition of the present
invention, water is present in an amount from about 0.5 wt % to
about 40 wt %, more preferably 1.0 wt % to 30 wt %, and most
preferably 2.0 wt % to 25 wt % based on the total weight of the
dental composition. This preferred amount of water is particularly
suitable for a dental composition in the form of a dental glass
ionomer cement, that is a dental composition comprising the
reactive particulate filler (c) and the polyacidic polymer (d).
[0323] One-Pack or Multi-Pack Dental Composition
[0324] The present dental composition may be a one-pack or a
multi-pack dental composition.
[0325] The term "one-pack" as used herein means that all components
of the dental composition are comprised in one single pack such as
a capsule having at least two chambers.
[0326] The term "multi-pack" as used herein means that the
components of the dental composition are comprised in a multitude
of separate packs. For example, a first part of components is
comprised in a first pack, while as second part of components is
comprised in a second pack, a third part of components may be
comprised in a third pack, a fourth part of components may be
comprised in a fourth pack, and so on.
[0327] Preferably, the dental composition is a composition of two
or more packs, more preferably a two-pack composition. For a
two-pack dental composition, a two-pack powder/liquid composition
is preferred.
[0328] Preferably, in a two-pack powder/liquid composition, the
powder pack comprises the particulate carrier (b2) and optionally
the reactive particulate filler (c), and the liquid pack comprises
the compound having a polymerizable double bond (a) and optionally
the polyacidic polymer(d).
[0329] Use of a Particulate Carrier
[0330] A particulate carrier displaying multiple covalently bonded
tertiary amino groups and/or tertiary phosphine groups on the
surface, may be used in a dental composition for crosslinking
polymer chains formed by polymerizing a compound having a
polymerizable double bond.
[0331] Preferably, the above described particulate carrier is the
particulate carrier (b2) described above for the dental
composition. Furthermore, preferably, in the use of the particulate
carrier, the dental composition is a dental composition as
described above.
[0332] The invention will now be further illustrated by the
following Examples.
EXAMPLES
Example 1
Synthesis of 4-(dimethylamino)-N-[3-(triethoxysilyl)propyl]
benzamide (SAR 1-155-1)
[0333] To a solution of 3.47 g (19 mmol)
3-Aminopropyltrimethoxysilane in 100 mL Dichloromethane were added
dropwise 2.16 g (21 mmol) triethylamine at 0-5.degree. C.
Thereafter, a suspension of 4.0 g (22 mmol) Dimethylamino benzoyl
chloride in 40 ml Dichloromethane was dropped to the first solution
under ice cooling and stirred for 1 hour under cooling. Then the
reaction mixture was stirred overnight and the precipitated product
was filtered off and dried.
##STR00026##
[0334] C.sub.18H.sub.32N.sub.2O.sub.4Si, M.sub.n=368.55 g/mol
[0335] .sup.13C NMR (DMSO-d.sub.6): .delta. (ppm)=167.67 (CONH),
152.92 (Ar--N(CH.sub.3).sub.2), 130.82 (Ar--NH), 118 (Ar), 110.70
(Ar), 45.45 (NH--CH.sub.2), 39.9 (NCH.sub.3), 22.2
(CH.sub.2CH.sub.2 CH.sub.2), 10.16 (CH.sub.3)
Condensation of 4-(dimethylamino)-N-[3-(triethoxysilyl)propyl]
benzamide to Nanocondensate 1
[0336] The raw product was dispersed in 50 mL water in an
ultrasound bath. After 1 hour 0.8 g Ammonium fluoride was added and
treated for another hour in the ultrasound bath. Then, the Water
was removed in vacuum and the product was dried at 50.degree. C.
and 50 mbar.
[0337] Yield: 5.41 (87%)
Example 2
Condensation of 3-Aminopropyl triethoxysilane onto Glass Filler
(REN 1-104-1)
[0338] 10.2 g Aerosil OX-50 was dispersed in 100.2 g isopropanol.
0.24 g (3-Aminopropyl) trimethoxy silane were added and the mixture
was stirred at 50.degree. C. for 5 minutes. Solvent was evaporated
at 125 mbar and 50.degree. C. by rotary evaporation. Afterward the
powder was dried at 80.degree. C. overnight.
Reaction to 4-(dimethylamino)-N-[3-(triethoxysilyl)propyl]
benzamide Modified Aeorsil (JBR 3-147-1)
[0339] A solution of 0,371 g 4-(dimethylamino) Benzoyl chloride in
80 ml ice cooled Dichloromethane was added to a suspension of 7.42
g of 3-Aminopropyl triethoxysilane modified Aerosil (REN 1-104-1)
and triethylamine in 100 ml Dichloromethane, stirred for 3 h at
4.degree. C. and additional stirred overnight at room temperature.
The supernatant solution was decanted, washed twice with 50 ml DCM
and dried in a vacuum oven.
[0340] Yield: 4.23 g of a white powder
Application Example 1
Liquid
[0341] In 10 g ethoxylated Bisphenol A dimethacrylate were
dissolved homogeniously 0.05 g camphorquinone.
Powder
[0342] To 20 g of a barium-alumosilicate glass (TPH.sup.3 Spectrum
Glass) were added 1.5 g of Nanocondensate 1 and homogenized by
tumbling for 30 min.
[0343] 15 g of the powder and 5 g of the liquid prepared as
described above were put in a Speedmixer MA-QC-165 (60 ml cup)
using the following mixing procedure: two times mixing speed 1500
rpm and time 3 min, finally, mixing speed 1000 rpm, time 3 min and
vacuum 100 mbar.
[0344] The obtained composite was irradiated with a SmartLite Focus
for 20 s resulting in a hard polymerized composite material.
Application Example 2
Liquid
[0345] In 10 g ethoxylated Bisphenol A dimethacrylate were
dissolved homogeneously 0.05 g camphorquinone.
Powder
[0346] To 20 g of a barium-alumosilicate glass (TPH.sup.3 Spectrum
Glass) were added 1.5 g of
4-(dimethylamino)-N-[3-(triethoxysilyl)propyl] benzamide modified
Aerosil (JBR 3-147-1) and homogenized by tumbling for 30 min.
[0347] 15 g of the powder and 5 g of the liquid prepared as
described above were put in a Speedmixer MA-QC-165 (60 ml cup)
using the following mixing procedure: two times mixing speed 1500
rpm and time 3 min, finally, mixing speed 1000 rpm, time 3 min and
vacuum 100 mbar.
[0348] The obtained composite was irradiated with a SmartLite Focus
for 20 s resulting in a hard polymerized composite material.
* * * * *