Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
1999-01-25
2003-11-25
Szekely, Peter (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C524S115000, C526S301000
Reexamination Certificate
active
06653375
ABSTRACT:
The present invention relates to urethane di(meth)acrylate derivatives of 1,3-bis(1-isocyanato-1-methylethyl)benzene and to dental materials on the basis of these substances.
Urethane (meth)acrylates find practical applications inter alia as a constituent of adhesives, coatings and dental materials (R. Holman (Pub.), U.V. and EB. Curing Formulation for Printing Inks, Coatings and Paints, SITA-Technology, London 1984, 27; J. P. Foussier, J. F. Rabek (Pub.), Radiation Curing in Polymer Science and Technology, Vol. IV, Elsevier Applied Science, London and New York 1993, 387). A monomer which is used particularly frequently in the dental field is 7,7,9-trimethyl-4,13-dioxo-3,14-dioxa-5, 12-diazahexadecan-1,16-diyldimethacrylate (UDMA) which is accessible by reaction of one mole of 2,2,4-trimethylhexa-methylene diisocyanate with two moles of 2-hydroxyethyl methacrylate (HEMA) (cf. e.g. DE 195 44 671).
However, the refractive index of UDMA, at n
D
=1.483, is clearly different from the refractive index of customary dental filling materials (ca. 1.52 to 1.55), so that UDMA and other aliphatic urethane dimethacrylates are frequently combined with bis-GMA, the addition product of methacrylic acid and bisphenol-A-diglycidyl ether (refractive index n
D
=1.549) to match the refractive index to the filler (cf. e.g. DE OS 24 11 760). The mechanical properties of the materials can also be improved by the addition of bis-BMA.
Through the matching of the refractive indices, a greater through-curing depth of the dental materials upon photopolymerization is achieved, but, because of the hydroxyl groups present, bis-GMA encourages the water absorption of the materials, which leads to a reduced durability under moist conditions. Moreover, bis-GMA frequently contains impurities, which are hard to remove, of bisphenol-A which has a pronounced oestrogenic action.
In addition to UDMA, the use of other di(meth)acrylate urethanes has been described. M. G. Buonocore and C. A. Casciani, New York State Dental Journal 35 (1969) 135, describe for example addition products of two moles of HEMA and one mole each of 2,4-toluylene diisocyanate, hydrogenated diphenylmethane diisocyanate, naphthalene diisocyanate or hexanemethylene diisocyanate. These are all crystalline compounds which can be processed to dental materials only together with liquid monomers.
U.S. Pat. No. 4,400,159 discloses urethane diacrylates which are obtained by reaction of aliphatic and aromatic diisocyanates with 3-methacrylol-2-hydroxypropyl esters. However, the substances tend to become discoloured, and the aromatic derivatives are crystalline compounds. These monomers are preferably combined with bis-GMA.
DE 195 44 671 A1 discloses urethane (meth)acrylates with cyclic carbonate groups which are said to show an increased speed of polymerization and a lower sensitivity to polymerization inhibition by oxygen.
U.S. Pat. No. 4,952,241, EP 0 254 185 B1, U.S. Pat. No. 4,904,750 and EP 0 658 582 A1 disclose prepolymeric (meth)acryl urethane derivatives which can be used above all as flexibilizing monomers or dilution monomers in combination with bis-GMA.
U.S. Pat. No. 4,386,912 relates to dental filling materials on the basis of tetrafunctional urethane acrylate monomers, which can be prepared by reaction of glycerol dimethacrylate with aromatic or aliphatic diisocyanates. Aliphatic diisocyanates are preferred as regards the coloration of the cured product.
B. Nabeth, J. F. Gerard, J. P. Pascault, J. Appl. Polym. Sci. 60 (1996) 2113, describe the synthesis of polyurethane (meth)-acrylates on the basis of polycaprolactone macrodiols using 1,3-bis (1-isocyanato-1-methylethyl)benzene (TMXDI). Low-molecular-weight urethane di(methacrylate) derivatives on the basis of TMXDI are not known at present.
The object of the invention is to prepare urethane di(meth)-acrylate derivatives capable of flowing and capable of polymerization, whose refractive index is compatible with that of customary dental filling materials, which do not to tend towards discolorations and which can replace bis-GMA in dental materials without impairing the mechanical properties of the materials.
This object is achieved by urethane di(meth)acrylate derivatives of 1,3-bis(1-isocyanato-1-methylethyl)benzene according to Formula (I),
in which
R is hydrogen or a straight-chained C
1
-C
8
alkyl radical, preferably hydrogen, methyl, ethyl, propyl, butyl or hexyl, quite particularly preferably hydrogen or methyl and
X and Y independently of each other stand for
in which
R
1
is a substituted or unsubstituted C
6
- to C
12
-aryl or C
7
- to C
16
-alkyl aryl or C
7
- to C
12
-aryl alkyl radical and
R
2
is hydrogen, a C
1
- to C
5
-alkyl or a substituted or unsubstituted C
6
- to C
12
-aryl radical;
R
3
is hydrogen or a methyl radical and
R
4
is a C
1
- to C
8
-alkylene radical which can be interrupted by oxygen atoms, or is a phenylene radical;
R
5
is hydrogen or a methyl radical,
R
6
is a substituted or unsubstituted C
6
- to C
2
-aryl or C
7
- to C16-alkyl aryl or C
7
- to C
12
-aryl alkyl radical,
Z is —CO— or a chemical bond and
W stands for oxygen, sulphur or NR
7
, whereby
R
7
is hydrogen or a straight-chained C
1
- to C
6
-alkyl radical.
R and R
7
preferably have the same meaning.
The aromatic groups both of the aryl and of the alkyl aryl radicals can be singly or repeatedly, preferably singly, substituted. Preferred substituents are halogen, in particular bromine, —OCH
3
, —OH, —CN, —CH
3
, —C
2
H
5
, —NO
2
—COOH and —COOCH
3
.
Preferred C
7
- to C
12
-aryl alkyl radicals are benzyl, a methyl-benzyl, &agr;,&agr;-dimethylbenzyl and &agr;,&agr;-diethylbenzyl, in particular benzyl.
Preferred definitions which can be chosen independently of one another are:
R
1
hydrogen or —CH
3
,
R
2
—CH
3
, —C
2
H
5
, a benzyl or phenyl radical,
R
3
hydrogen or a methyl radical,
R
4
an ethylene, propylene, triethylene, butylene or phenylene radical,
R
5
a methyl radical,
R
6
a benzyl, phenyl or substituted phenyl radical,
W oxygen, sulphur or NH,
Z —CO— or a chemical bond and/or
R
7
hydrogen.
Quite particularly preferred definitions which can be chosen independently of each other are:
R
1
hydrogen,
R
2
hydrogen, a benzyl or phenyl radical,
R
3
a methyl radical,
R
4
an ethylene, triethylene or propylene radical,
R
5
a methyl radical,
R
6
a benzyl radical,
W oxygen,
Z —CO— and/or
R
7
hydrogen.
Furthermore, urethane di(meth)acrylate derivatives in which X and Y have the same meaning are preferred.
Particularly preferred urethane di(meth)acrylate derivatives are:
Furthermore, compounds according to Formula I in which R and R
3
independently of each other, are hydrogen or methyl and R
4
is ethylene or propylene are particularly preferred.
The urethane di(meth)acrylate derivatives according to the invention of formula (I) can be prepared by reaction of commercial 1,3-bis(1-isocyanato-1-methylethyl)benzene (TMXDI) with corresponding hydroxy(meth)acrylates X—OH or Y—OH and optionally subsequent alkylation of the formed adducts for example with a dialkyl sulphate.
The preparation of the hydroxy(meth)acrylates X—OH and Y—OH can take place in a manner known per se (cf. e.g. C. Ferri, Reaktionen der organischen Synthese [
Organic Synthesis Reactions]
, G. Thieme Verlag, Stuttgart 1978). The Baylis-Hillman reaction, catalysed by tertiary amines, of acrylates with aldehydes according to the reaction equation
in which R
1
and R
2
have the meaning given above, is preferred. For example, 2-hydroxymethyl acrylic acid benzyl ester can be prepared by reaction of acrylic acid benzyl ester with formaldehyde:
Concrete Example
Further preferred is the unstoichiometric esterification of dihydroxy compounds with (meth)acrylic acid or (meth)acrylic acid chloride according to the reaction equation
in which R
3
and R
4
have the meaning given above and U=Cl or is OH. For example, 4-hydroxyphenyl methacrylate is accessible by reaction of hydroquinone with methacrylic acid chloride:
Concrete Example
Moreover, the synthesis of suitable hydroxy(meth)acrylates can
Fischer Urs Karl
Moszner Norbert
Rheinberger Volker
Völkel Thomas
Ivoclar AG
Nixon & Peabody LLP
Szekely Peter
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