Moisture-curable hot melt silicone adhesive compositions including an alkoxy-functional siloxane reactive resin

1. A moisture-curable hot melt silicone adhesive composition comprising:

(A) a reactive resin comprising a hydrosilylation reaction product of a reaction of:

an alkenyl-functional siloxane resin comprising R 3 SiO 1/2 units and SiO 4/2 units, wherein each R is independently a monovalent hydrocarbon radical having 1 to 6 carbon atoms with the proviso that at least one R is an alkenyl radical,

wherein the molar ratio of the R 3 SiO 1/2 units to SiO 4/2 units has a value of from 0.5/1 to 1.5/1,

a first alkoxysilane-functional organosiloxane compound of a formula HSi(R 2 ) 2 OSi(R 2 ) 2 CH 2 CH 2 SiR 2 z (OR 2 ) 3-z , wherein each R 2 is independently a monovalent hydrocarbon having 1 to 6 carbon atoms and wherein the subscript z is 0 or 11, and

in the presence of a first hydrosilylation catalyst;

(B) a reactive polymer comprising a (trimethoxysilylethyl)tetramethyldisiloxane-terminated polydimethylsiloxane having a viscosity of from 500 to 60,000 cps;

(C) a catalyst; and

(D) a crosslinker.

2. The composition according to claim 1 , wherein a weight average molecular weight M w of the reactive resin (A) is from 12,000 to 30,000 g/mole.

3. The composition according to claim 1 , wherein the reactive resin (A) has a hydroxyl content that is less than 1% by weight based on a total weight of the reactive resin (A).

4. The composition according to claim 1 , wherein a alkenyl radical content of the alkenyl-functional siloxane resin is 0.6 to 2.2 eight percent of a total weight of the alkenyl-functional siloxane resin.

5. The composition according to claim 1 , wherein the reactive resin (A) further comprises, as a part of its hydrosilylation reaction product, an endcapper according to a formula R 3 3 SiO—(R 3 2 SiO) s —SiR 3 2 H or R 4 3 SiO—(R 4 2 SiO) t —(HR 4 SiO)—SiR 4 3 , or combinations thereof, wherein each R 3 and R 4 is independently a hydrocarbon radical and wherein the subscripts s and t independently have values ranging from 0 to 10.

6. The composition according to claim 1 , wherein the reactive resin (A) further comprises, as a part of its hydrosilylation reaction product, an alkenyltrialkoxysilane according to a formula AlkSi(OR 5 ) 3 , wherein R 5 is a monovalent hydrocarbon having 1 to 6 carbon atoms, wherein Alk represents an alkenyl group having 2 to 6 carbon atoms, and wherein the alkenyl group is at the molecular terminal of the alkenyltrialkoxysilane of the reactive resin (A).

7. The composition according to claim 1 , wherein the crosslinker (D) comprises a silane represented by monomers of a formula R 10 4-y SiX y or oligomeric reaction products thereof in which R 10 is selected from the group consisting of hydrocarbon radicals and substituted hydrocarbon radicals having 1-6 carbon atoms, X is a hydrolyzable group and the subscript y has a value of 2 to 4.

8. The composition according to claim 1 , wherein a weight ratio of reactive resin (A) to reactive polymer (B) is from 40:60 to 80:20.

9. A method for forming a substrate assembly, the method comprising:

(1) providing the moisture-curable hot melt silicone adhesive composition according to claim 1 ;

(2) heating the moisture-curable hot melt silicone adhesive composition to a temperature sufficient to induce flow of the composition;

(3) disposing the heated composition onto a first substrate and a second substrate such that the moisture-curable hot melt silicone adhesive composition is located between the first substrate and the second substrate; and

(4) curing the moisture-curable hot melt silicone adhesive composition to bond the first substrate to the second substrate to form the substrate assembly.

10. A substrate assembly formed by the method according to claim 9 .

11. A method for forming a moisture-curable hot melt adhesive composition, the method comprising:

(a) forming a reactive resin comprising a hydrosilylation reaction product of a reaction of:

an alkenyl-functional siloxane resin comprising R 3 SiO 1/2 units and SiO 4/2 units, wherein each R is independently a monovalent hydrocarbon radical having 1 to 6 carbon atoms with the proviso that at least one R is an alkenyl radical, wherein the molar ratio of the R 3 SiO 1/2 units to SiO 4/2 units has a value of from 0.5/1 to 1.5/1, and

a first alkoxysilane-functional organosiloxane compound of the formula HSi(R 2 ) 2 OSi(R 2 ) 2 CH 2 CH 2 SiR 2 z (OR 2 ) 3-z , wherein each R 2 is independently a monovalent hydrocarbon having 1 to 2 carbon atoms and wherein the subscript z is 0 or 1,

in the presence of a first hydrosilylation catalyst;

(b) providing a (trimethoxysilylethyl)tetramethyldisiloxane-terminated polydimethylsiloxane having a viscosity of from 500 to 60,000 cps as a reactive polymer;

(c) mixing the reactive resin and the reactive polymer to form a first mixture;

(d) heating the first mixture to a temperature ranging from 140° C. to 180° C. and extruding the mixture through a first extruder to form an extruded mixture;

(e) cooling the extruded mixture to a temperature below 95° C. to provide a cooled extruded mixture;

(f) introducing and mixing a moisture cure catalyst and a crosslinker to the cooled extruded mixture to form a second mixture; and

(g) extruding the second mixture through a second extruder to form a moisture-curable hot melt adhesive composition.

12. The method according to claim 11 , wherein the reactive resin further comprises, as a part of its hydrosilylation reaction product, an endcapper according to the formula R 3 3 SiO—(R 3 2 SiO) s —SiR 3 2 H or R 4 3 SiO—(R 4 2 SiO) t —(HR 4 SiO)—SiR 4 3 , or combinations thereof, wherein each R 3 and R 4 is independently a hydrocarbon radical and wherein the subscripts s and t independently have values ranging from 0 to 10.

13. A moisture curable hot melt adhesive composition formed in accordance with the method according to claim 11 .