Aqueous emulsions comprising polyisocyanate/acetal solvent compositions and coatings/adhesives produced therefrom
Water-emulsifiable polyisocyanate compositions admixed with at least one solvent of formula (1) (R 1 O) 2 C(R 2 )—X—R 3 are formulated into aqueous emulsions which advantageously further comprise a compound, bearing a mobile hydrogen function, or a compound containing precursor functions capable of liberating hydroxyl functions, and are useful for producing coatings on a variety of substrates, e.g., made of cement, wood or leather in particular, and also for producing adhesives.
1. A polyisocyanate/acetal solvent mixed composition which comprises:
a water-emulsifiable polyisocyanate composition comprising, in admixture, at least one polyisocyanate and at least one hydrophilic additive; and
at least one solvent having the formula (1):
in which:
the radicals R 1 , which may be identical or different and optionally linked together, are each a linear or branched C 1 -C 4 alkyl radical:
R 2 is H or a linear or branched C 1 -C 4 alkyl radical;
X is a linear or branched divalent alkyl radical having from 1 to 6 carbon atoms, or a covalent single bond; and
R 3 is H, C(OR 1 ) 2 R 2 , C(O)OR 1 , OC(O)R 2 or OC(O)OR 1 .
2. The polyisocyanate/acetal solvent mixed composition as defined by claim 1 , said solvent containing up to 20 carbon atoms and having a melting point of at most 0° C. and a boiling point of at most 350° C.
3. The polyisocyanate/acetal solvent mixed composition as defined by claim 1 , said solvent corresponding to formula (1) in which R 2 is H or CH 3 , X is a covalent bond and R 3 is CH 3 , —(CH)(OR 1 ) 2 or —C(═O)(OR 1 ).
4. The polyisocyanate/acetal solvent mixed composition as defined by claim 1 , said at least one hydrophilic additive having an anionic function and a fragment of a polyethylene glycol chain with at least one ethyleneoxy structural unit.
5. A precursor mixture which comprises:
a polyisocyanate composition;
at least one solvent of formula (1)
in which:
the radicals R 1 , which may be identical or different and optionally linked together, are each a linear or branched C 1 -C 4 alkyl radical;
R 2 is H or a linear or branched C 1 -C 4 alkyl radical; X is a linear or branched divalent alkyl radical having from 1 to 6 carbon atoms, or a covalent single bond; and
R 3 is H, C(OR 1 ) 2 R 2 , C(O)OR 1 , OC(O)R 2 or OC(O)OR 1 .
6. The polyisocyanate/acetal solvent mixed composition as defined by claim 1 , comprising a solvent of formula (1) in which the groups R 1 are methyl or ethyl radicals, X is a covalent bond and R 2 is hydrogen.
7. The polyisocyanate/acetal solvent mixed composition as defined by claim 6 , comprising at least one solvent selected from among 1,1,2,2-tetraethoxyethane, 1,1,2,2-tetramethoxyethane, methyl 2,2-dimethoxyacetate and ethyl 2,2-diethoxyacetate.
8. The polyisocyanate/acetal solvent mixed composition as defined by claim 1 , said polyisocyanate comprising at least one product of homocondensation or heterocondensation of an alkylene diisocyanate, or a biuret or trimer product, or a urea, urethane, allophanate, ester, amide, acylurea, isocyanurate, oxadiazinetrione, immino-dimer, immino-trimer (imminotriazadione), immino-oxadiazinedione (asymmetrical trimer) or diazetidinedione (dimer) function, or mixture thereof.
9. The polyisocyanate/acetal solvent mixed composition as defined by claim 8 , said polyisocyanate comprising at least one homocondensation or heterocondensation product of the following aliphatic, (cyclo- or aryl-) aliphatic isocyanate monomers:
1,6-hexamethylene diisocyanate (HDI),
1,12-dodecane diisocyanate,
1,3-cyclobutane diisocyanate,
1,3- and/or 1,4-cyclohexane diisocyanate,
1-isocyanato-3,3,5-trimethyl-5-diisocyanatomethylcyclohexane (isophorone diisocyanate,
IPDI),
isocyanatomethyloctylene diisocyanate (TTI),
2,4- and/or 2,6-hexahydrotoluylene diisocyanate (H 6 TDI),
hexahydro-1,3 and/or 1,4-phenylene diisocyanate,
perhydro-2,4′ and/or 4,4′-diphenylmethane diisocyanate (H 12 MDI), and/or an aromatic amino precursor or perhydrogenated carbamate,
a bisisocyanatomethylcyclohexane (BIC),
a bisisocyanatomethylnorbornane (NBDI),
2-methylpentamethylene diisocyanate (MPDI),
a tetramethylxylylene diisocyanate (TMXDI),
lysine diisocyanate and also an ester of lysine di- or triisocyanate (LDI or LTI),
2,4- and/or 2,6-toluylene diisocyanate,
2,4′- and/or 4,4′-diphenylmethane diisocyanate (MDI),
1,3- and/or 1,4-phenylene diisocyanate,
4,4′,4″-triphenylmethane triisocyanate, and
an oligomer of MDI, or TDI.
10. The polyisocyanate/acetal solvent mixed composition as defined by claim 9 , said polyisocyanate comprising at least one product of the homocondensation of isocyanates selected from HDI and IPDI, or from mixture thereof.
11. An aqueous emulsion obtained from the mixed composition as defined by claim 1 , the aqueous emulsion further comprising at least one compound bearing at least one mobile-hydrogen function selected from the group consisting of primary or secondary hydroxyl functions, phenols, primary and/or secondary amines, carboxyl functions and a thiol function, or a compound containing precursor functions that release free hydroxyl functions.