Isocyanate functional adhesive which bonds primerless to silanated acrylic polyol based coatings
Disclosed is a composition including one or more isocyanate functional prepolymers; one or more catalysts for the reaction of isocyanate moieties and active hydrogen containing moieties; one or more mercapto silanes; one or more amino silanes, isocyanato silanes or a mixture thereof; one or more reinforcing fillers comprising one or more high surface area carbon blacks; one or more untreated calcium carbonates; one or more polyisocyanates having an isocyanate functionality of about 2 or greater; and one or more linear plasticizers. Preferably, the isocyanate functional prepolymer is prepared in the presence of at least a portion of the linear plasticizer. Preferably, the isocyanate functional polymer is prepared in the presence of a dialkyl malonate. The composition may be one-part adhesive composition. Also disclosed are methods of applying the compositions to substrates. The composition bonds primerlessly to hard to bond to coatings, such as coatings prepared from compositions including a silanated component, such as a silanated acrylopolyols, or having silica clusters.
1. A composition comprising:
a) one or more isocyanate functional prepolymers;
b) one or more catalysts for the reaction of isocyanate moieties and active hydrogen containing moieties;
c) 0.6 to about 1.1 percent by weight of one or more mercapto silanes, based on the weight of the composition;
d) 0.1 to 1.3 percent by weight of one or more amino silanes, isocyanato silanes or a mixture thereof, based on the weight of the composition;
e) one or more reinforcing fillers comprising one or more high surface area carbon blacks;
f) one or more untreated calcium carbonates;
g) one or more polyisocyanates having an isocyanate functionality of about 2 or greater; and
h) a linear plasticizer, wherein the isocyanate functional prepolymer is prepared in the presence of the linear plasticizer and/or the plasticizer is added after preparing the isocyanate functional prepolymer;
wherein the composition optionally includes a dialkyl malonate.
2. A composition according to claim 1 , wherein the composition includes the dialkyl malonate and the isocyanate functional prepolymer is prepared in the presence of at least a portion of the dialkyl malonate.
3. A composition according to claim 1 , wherein the composition comprises one or more amino silanes.
4. A composition according to claim 1 , wherein the amino silane has one secondary amine.
5. A composition according to claim 1 wherein the amino silane is a bis(di or tri alkoxy silyl alkyl) amine.
6. A composition according to claim 1 wherein the reinforcing filler has an oil absorption number of about 80 to about 120 g/100 ml.
7. A composition according to claim 1 , wherein the dialkyl malonate is present in an amount of about 0.05 to about 1 percent by weight of the composition.
8. A composition according to claim 1 , wherein the linear plasticizer is a linear phthalate.
9. A composition according to claim 1 , wherein the one or more polyisocyanates having an isocyanate functionality of about 2.0 or greater comprises a trimer of an aliphatic polyisocyanate, a polymeric MDI or a mixture thereof.
10. A composition according to claim 1 , wherein the one or more polyisocyanates having an isocyanate functionality of about 2.0 or greater comprises a trimer of an aliphatic polyisocyanate.
11. A composition according to claim 1 , which comprises:
a) from about 30 to about 65 percent by weight of the one or more isocyanate functional prepolymers (preferably prepared in the presence of a linear plasticizer and a dialkyl malonate) including any linear plasticizer and any dialkyl malonate in the isocyanate prepolymers (preferably the one or more isocyanate functional prepolymers includes a portion having one or more isocyanate groups in an amount of about 22 percent by weight to about 55 percent by weight;
b) from about 0.03 to about 1.6 percent by weight of the one or more catalysts for the reaction of isocyanate moieties and active hydrogen containing moieties;
c) from about 0.3 to about 1.5 percent by weight of the one or more mercapto silanes;
d) from about 0.4 to about 2.0 percent by weight of the one or more amino silanes, isocyanato silanes, or a mixture thereof;
e) from about 15 to about 30 percent by weight of the one or more reinforcing fillers comprising one or more high surface area carbon blacks; and
f) from about 8 to about 20 percent by weight of the one or more untreated calcium carbonates; and
g) from greater than 0 to about 3 percent by weight of the one or more polyisocyanates having an isocyanate functionality of about 2.0 or greater; and
the dialkyl malonate is present in an amount of about 0.05 to about 1 percent by weight, all percentages are based on the weight of the composition.