Polyurethane Reactive Hot Melt With Long Pot-Life Under Heat
Disclosed is a moisture reactive hot melt adhesive composition prepared from a combination comprising a polyisocyanate; a polyol; a MA-SCA acid; one or both of an inorganic filler or an organosilane; optionally a thermoplastic polymer; and optionally one or more additives. Useful polyols include poly(hexanediol adipate), a polyester diol having a structure of Formula 1 or of Formula 2 and combinations thereof. Formula 1 is: H—[O(CH 2 ) m OOC(CH 2 ) n CO] k —O(CH 2 ) m —OH; m and n are each an even integer; m+n =8; m and n are each independently selected from 2, 4 or 6; k is an integer from 9 to 55; and the polyol of Formula 1 has a number average molecular weight of about 2,000 to about 11,000. Formula 2, a polycaprolactone polyol, is: HO—[(CH 2 ) 5 COO] p —R 1 —[OOC(CH 2 ) 5 ] 1 —OH; R 1 is an initiator such as 1,4′-butanediol, 1,6′-hexanediol, or ethylene glycol; p is an integer from 0 to 96; q is an integer from 0 to 96; p+q=16 to 96; and the polyol has a number average molecular weight of about 2,000 to about 11,000 or less.
1 . A moisture reactive hot melt adhesive polyurethane composition that is the product of a mixture comprising a polyisocyanate; a polyol; a MA-SCA acid; one or both of an inorganic filler or an organosilane; optionally a thermoplastic polymer; and optionally one or more additives.
2 . A moisture reactive hot melt adhesive composition as recited in claim 1 wherein the polyol is selected from the group consisting of poly(alkyldiol adipate) or a polyester diol having a structure of Formula 1 or of Formula 2;
wherein Formula 1 is:
H—[O(CH 2 ) m OOC(CH 2 ) n CO] k —O(CH 2 ) m —OH;
m and n are each an even integer; m+n=8; m and n are each independently selected from 2, 4 or 6; k is an integer from 9 to 55; and the polyol of Formula 1 has a number average molecular weight of about 2,000 to about 11,000; and
Formula 2 is:
HO—[(CH 2 ) 5 COO] p —R 1 —[OOC(CH 2 ) 5 ] q —OH;
R 1 is an initiator; p s an integer from 0 to 96; q is an integer from 0 to 96; p+q=16 to 96; and the polyol has a number average molecular weight of about 2,000 to about 11,000.
3 . A moisture reactive hot melt adhesive composition as recited in claim 2 comprising both poly(alkyldiol adipate) and the polyester diol having a structure of Formula 1 or of Formula 2.
4 . A moisture reactive hot melt adhesive composition as recited in claim 2 wherein the poly(alkyldiol adipate) is selected from poly(alkyldiol adipate), poly(butanediol adipate) or both.
5 . A moisture reactive hot melt adhesive composition as recited in claim 2 wherein R 1 is a residue of a glycol initiator selected from 1,4′-butanediol, 1,6′-hexanediol, ethylene glycol and combinations thereof.
6 . A moisture reactive hot melt adhesive composition as recited in claim 2 , wherein the polyester diol has a number average molecular weight of from 2,000 to 10,000 and is present in an amount of from 10 to 35% by weight based on the total adhesive weight.
7 . A moisture reactive hot melt adhesive composition as recited in claim 1 wherein said polyol is a polyether polyol having a number average molecular weight of from 1,500 to 6,000 and being present in an amount of from 15 to 40% by weight based on the total adhesive weight.
8 . A moisture reactive hot melt adhesive composition as recited in claim 1 wherein the polyol comprises at least one polypropylene glycol.
9 . A moisture reactive hot melt adhesive composition as recited in claim 1 , wherein the thermoplastic polymer is an acrylic polymer having a weight average molecular weight of from 30,000 to 80,000 and is present in an amount of from 10 to 40% by weight based on the total adhesive weight.
10 . A moisture reactive hot melt adhesive composition as recited in claim 1 , wherein the thermoplastic polymer is an acrylic polymer having a glass transition temperature of from 35 to 85° C. and a hydroxyl number of less than 8.
11 . A moisture reactive hot melt adhesive composition as recited in claim 1 , wherein said polyisocyanate is present in an amount of from 5 to 40% by weight based on the total adhesive weight; and/or the polyisocyanate comprises 4,4′-methylenebisphenyldiisocyanate (MDI).
12 . A moisture reactive hot melt adhesive composition as recited in claim 1 , wherein said inorganic filler is present in an amount of from about 10 to 70% by weight based on the total adhesive weight; and/or wherein said inorganic filler is present and comprises calcium carbonate.
13 . A moisture reactive hot melt adhesive composition as recited in claim 1 , further comprising the additive selected from additional filler, plasticizer, catalyst, colorant, rheology modifier, flame retardant, UV pigment, nanofiber, defoamer, tackifier, curing catalyst, anti-oxidant, adhesion promoter, stabilizer, a thixotropic agent and mixtures thereof.
14 . A moisture reactive hot melt adhesive composition as recited in claim 1 , further comprising 2,2′-dimorpholinildiethylether (DMDEE).
15 . An article of manufacture comprising the moisture reactive hot melt adhesive composition according to claim 1 .
16 . A method of bonding two substrates together comprising:
providing a first substrate and a second substrate;
providing the hot melt adhesive according to claim 1 ;
heating the provided adhesive to molten form;
applying the adhesive in molten form to the first substrate;
bringing a second substrate into contact with the adhesive on the first substrate; and
allowing the adhesive to cool and cure to an irreversible solid form.
17 . Cured reaction products of the hot melt adhesive composition according to claim 1 .