Dental adhesive

Abstract

A one-part self-etching, self-priming dental adhesive having a pH of at most 2, which comprises an aqueous mixture containing (i) one or more polymerizable monomers optionally containing an acidic group, (ii) optionally one or more organic or inorganic acids, (iii) a polymerization initiator, and (iv) a thermal polymerisation inhibitor of the following formula (I): wherein R′ 1 represents a hydrogen atom, or a saturated hydrocarbon group having 1 to 18 carbon atoms. R′ 2 , which may be the same or different if more than one R′ 2 is present, independently represent a saturated hydrocarbon group having 1 to 18 carbon atoms, and c represents an integer of from 1 to 4.

1 . One-part self-etching, self-priming dental adhesive having a pH of at most 2, which comprises an aqueous mixture containing
 (i) one or more polymerizable monomers optionally containing an acidic group,   (ii) optionally one or more organic or inorganic acids,   (iii) a polymerization initiator, and   (iv) a thermal polymerisation inhibitor of the following formula (I):   
     
       
         
         
             
             
         
       
       
         wherein 
         R′ 1  represents 
         a hydrogen atom, or a saturated hydrocarbon group having 1 to 18 carbon atoms. 
         R′ 2 , which may be the same or different if more than one R′ 2  is present, independently represent
 a saturated hydrocarbon group having 1 to 18 carbon atoms, and 
 
         c represents an integer of from 1 to 4. 
       
     
   
   
       2 . The adhesive according to  claim 1 , wherein the thermal polymerisation inhibitor of formula (I) is a compound of the following formula: 
     
       
         
         
             
             
         
       
       wherein 
       R′ 1  represents
 a hydrogen atom, or a saturated hydrocarbon group having 1 to 18 carbon atoms, and 
 
       R′ 2  represents
 a saturated hydrocarbon group having 1 to 18 carbon atoms. 
 
     
   
   
       3 . The adhesive according to  claim 1  or  2 , which is stable at storage for at least 10 days at 60° C. 
   
   
       4 . The dental adhesive according to  claim 1 ,  2  or  3 , wherein the saturated hydrocarbon group is a straight chain or branched C 1-18  alkyl group or a C 3-18  cycloalkyl group optionally substituted by one or more C 1-5  alkyl groups or a C 1-18  cycloalkylalkyl group optionally substituted by one or more C 1-5  alkyl groups. 
   
   
       5 . The dental adhesive according to  claim 1 ,  2  or  3 , wherein the saturated hydrocarbon group of R′ 2  is a branched C 1-18  alkyl group. 
   
   
       6 . The dental adhesive according to any one of the preceding claims, wherein R′ 2  is a tert.-butyl group. 
   
   
       7 . The dental adhesive according to any one of the preceding claims, wherein the inhibitor is TBHQ or BHA. 
   
   
       8 . The dental adhesive according to any one of the preceding claims, wherein the inhibitor is contained in an amount of from 0.01 to 0.5 mol %. 
   
   
       9 . The dental adhesive according to any one of the preceding claims, wherein the one or more polymerizable monomers comprises
 (a) a polymerizable acidic phosphoric acid ester monomer of the following formula (A):   
     
       
         
         
             
             
         
       
       
         wherein 
         the moieties Y independent from each other represent a hydrogen atom or 
         a moiety of the following formula (Y) 
       
     
     
       
         
         
             
             
         
       
       
         wherein
 Z 1  is COOR 10 , COSR 20 , CON(R 10 ) 2 , CONR 10 R 20 , or CONHR 10 , wherein
 R 10  and R 20  independently represent a hydrogen atom, 
  a C 1-18  alkyl group optionally substituted by a C 3-8  cycloalkyl group, 
  an optionally substituted C 3-8  cycloalkyl group, an optionally substituted C 4-18  aryl or heteroaryl group, 
  an optionally substituted C 5-18  alkylaryl or alkylheteroaryl group, or 
  an optionally substituted C 7-30  aralkyl group, whereby two R 1 , residues may form together with the adjacent nitrogen atom to which they are bound a 5- to 7-membered heterocyclic ring which may contain further nitrogen atoms or an oxygen atoms, and whereby the optionally substituted groups may be substituted by 1 to 5 C 1-5  alkyl group(s); 
 
 L represents an (a+b)-valent organic residue (whereby b is 1 when Y in formula (A) is within the round bracketsis) containing 2 to 45 carbon atoms and optionally heteroatoms such as oxygen, nitrogen and sulfur atoms, the carbon atoms including a+b carbon atoms selected from primary and secondary aliphatic carbon atoms, secondary alicyclic carbon atoms, and aromatic carbon atoms, each of said a+b carbon atoms linking a phosphate or 2-(oxa-ethyl)acryl derivative group; 
 a is an integer of from 1 to 10, preferably 1 to 5; 
 b is an integer of from 1 to 10, preferably 1 to 5; 
 
       
       provided that at least one Y is not hydrogen. 
     
   
   
       10 . The dental adhesive according to any one of the preceding claims, wherein the one or more polymerizable monomers comprises
 (b) one or more polymerisable acidic monomers selected from the group consisting of
 (b1) polymerisable acidic monomers of the following formula (B): 
   
     
       
         
         
             
             
         
       
       
         wherein 
         R 1  and R 2  independently represent
 a hydrogen atom, 
 an optionally substituted C 1-18  alkyl group, 
 an optionally substituted C 3-18  cycloalkyl group, 
 an optionally substituted C 5-18  aryl or heteroaryl group, 
 an optionally substituted C 5-18  alkylaryl or alkylheteroaryl group, 
 an optionally substituted C 7-30  aralkyl group, 
 whereby the optionally substituted groups may be substituted by 1 to 5 C 1 —, alkyl group(s); 
 L 1  represents a (c+d) valent organic residue containing 2 to 45 carbon atoms and optionally heteroatoms such as oxygen, nitrogen and sulfur, the carbon atoms including c+d carbon atoms selected from primary and secondary aliphatic carbon atoms, secondary alicyclic carbon atoms, and aromatic carbon atoms, each of said c+d carbon atoms linking a phosphonate or optionally substituted acrylamido group; and 
 
         c and d independently represent integers of from 1 to 10; 
         (b2) polymerisable acidic monomers of the following formula (C): 
       
     
     
       
         
         
             
             
         
       
       
         wherein 
         Z 2  independently has the same meaning as defined for Z 1 ; 
         L 2  represents an (e+0 valent organic residue containing 2 to 45 carbon atoms and optionally heteroatoms such as oxygen, nitrogen and sulfur atoms, the carbon atoms including e+f carbon atoms selected from primary and secondary aliphatic carbon atoms, secondary alicyclic carbon atoms, and aromatic carbon atoms, each of said e+f carbon atoms linking a sulphonate or optionally substituted 2-(oxa-ethyl)acryl derivative group; and 
         e and f independently represent an integer of from 1 to 10; 
         (b3) acidic monomers of the following formula (D): 
       
     
     
       
         
         
             
             
         
       
       
         wherein 
         R 3  and R 4  independently represent
 a hydrogen atom, 
 an optionally substituted C 1-18  alkyl group, 
 an optionally substituted C 3-18  cycloalkyl group, 
 an optionally substituted C 5-18  aryl or heteroaryl group, 
 an optionally substituted C 5-18  alkylaryl or alkylheteroaryl group, 
 an optionally substituted C 7-30  aralkyl group, 
 whereby the optionally substituted groups may be substituted by 1 to 5 C 1-5  alkyl group(s) 
 
         L 3  represents a (g+h) valent organic residue containing 2 to 45 carbon atoms and optionally heteroatoms such as oxygen, nitrogen and sulfur atoms, the carbon atoms including g+h carbon atoms selected from primary and secondary aliphatic carbon atoms, secondary alicyclic carbon atoms, and aromatic carbon atoms, each of said g+h carbon atoms linking a sulphonate or optionally substituted acrylamido group; and 
         g and h independently represent integers of from 1 to 10. 
       
     
   
   
       11 . The dental adhesive according to any one of the preceding claims, wherein the aqueous mixture further contains an organic water soluble solvent selected from the group of alcohols and ketones such as ethanol, propanol, butanol, acetone, methyl ethyl ketone. 
   
   
       12 . The dental adhesive according to any one of the preceding claims, wherein the polymerizable monomer of component (i) is characterized by one of the following formulas: 
     
       
         
         
             
             
         
       
       wherein 
       Z is Z 1  as defined in  claim 7  (R 4 ) is an optionally substituted alkylene group, and 
       n is an integer. 
     
   
   
       13 . The dental adhesive according to any one of the preceding claims, wherein said acidic polymerizable monomer is characterized by one of the following formulas: 
     
       
         
         
             
             
         
       
     
   
   
       14 . The dental adhesive according to any one of the preceding claims, wherein the polymerizable monomer of component (i) is characterized by one of the following formulas: 
     
       
         
         
             
             
         
       
       wherein 
       R 5  and R 6  independently represent
 a hydrogen atom or a substituted 
 a C 1  to C 18  alkyl group, 
 an optionally substituted C 3-18  cycloalkyl group, 
 an optionally substituted C 3-18  aryl or heteroaryl group, 
 an optionally substituted C 5-18  alkylaryl or alkylheteroaryl group, 
 an optionally-substituted C 7-30  aralkyl group, 
 
       R 7  represents a
 a divalent substituted or unsubstituted organic residue having from 1 to 45 carbon atoms, whereby said organic residue may contain from 1 to 14 oxygen and/or nitrogen atoms and is selected from a C 1  to C 18  alkylene group wherein from 1 to 6-CH 2 -groups may be replaced by a —N—(C═O)—CR 9 ═CH 2  group wherein R 9  is a hydrogen atom or a C 1  to C 18  alkyl group, a divalent substituted or unsubstituted C 3  to C 18  cycloalkyl or cycloalkylene group, a divalent substituted or unsubstituted C 4  to C 18  aryl or heteroaryl group, a divalent substituted or unsubstituted C 5  to C 18  alkylaryl or alkylheteroaryl group, a divalent substituted or unsubstituted C 7  to C 30  aralkyl group, and a divalent substituted or unsubstituted C 2  to C 45  mono-, di- or polyether group having from 1 to 14 oxygen atoms, 
 
       R 8  represents
 a saturated di- or multivalent substituted or unsubstituted C 2  to C 18  hydrocarbon group, a saturated di- or multivalent substituted or unsubstituted cyclic C 3  to C 18  hydrocarbon group, a di- or multivalent substituted or unsubstituted C 4  to C 18  aryl or heteroaryl group, a di- or multivalent substituted or unsubstituted C 5  to C 18  alkylaryl or alkylheteroaryl group, a di- or multivalent substituted or unsubstituted C 7  to C 30  aralkyl group, or a di- or multivalent substituted or unsubstituted C 2  to C 45  mono-, di-, or polyether residue having from 1 to 14 oxygen atoms, and 
 
       n is an integer. 
     
   
   
       15 . The dental adhesive according to any one of the preceding claims, wherein said polymerizable monomer is a mono-, bis- or poly(meth)acrylamide characterized by one of the following formulas: 
     
       
         
         
             
             
         
       
       
         
         
             
             
         
       
     
   
   
       16 . The dental adhesive according to any one of the preceding claims, which contains polymerizable monomers of components (i) in an amount of from 5 to 90 wt-%. 
   
   
       17 . The dental adhesive according to any one of the preceding claims, wherein said polymerization initiator is a photo initiator such as camphor quinone. 
   
   
       18 . The dental adhesive according to any one of the preceding claims, which further contains an inorganic filler and/or an organic filler. 
   
   
       19 . Use of a thermal polymerisation inhibitor of formula (I) defined in any one of  claims 1  or  2  in a one-part self-etching, self-priming dental adhesive having a pH of at most 2.