Applying adhesive stream of epoxy resin, rubber modified epoxy resin and capped isocyanate prepolymer

1. A method of applying an adhesive composition comprising applying a stream of the adhesive composition to a substrate at a speed of from about 200 to about 500 mm/s, wherein the adhesive composition comprises,

A. one or more epoxy resins;

B. one or more rubber modified epoxy resins;

C. one or more toughening compositions comprising the reaction product of one or more isocyanate terminated prepolymers and one or more capping compounds having one or more bisphenolic, phenolic, benzyl alcohol, aminophenyl or, benzylamino moieties wherein the reaction product is terminated with the capping compound;

D. one or more curing agents and one or more catalysts for epoxy resins which initiates cure at a temperature of about 100° C. or greater; and

E. optionally; fillers, adhesion promoters, wetting agents and rheological additives useful in epoxy adhesive compositions;

wherein the adhesive composition has a viscosity at 45° C. of about 20 Pa·s to about 400 Pa.

2. A method according to claim 1 wherein the toughening agent has a crosslink density of about 2 or less.

3. A method of claim 1 wherein the capping compound corresponds to the formula

wherein

R 4 is a direct bond or an alkylene, carbonyl, oxygen, carboxyloxy or amido moiety;

R 5 is independently in each occurrence an alkyl, alkenyl, alkyloxy or aryloxy moiety with the proviso that if p=1 then q=0;

X is O or —NR 6 with the proviso that X is O where p is 1; and that where p is 0, X is O in at least one occurrence;

o is independently in each occurrence 0 or 1 if p is 0, and 0 if p is 1;

p is independently in each occurrence 0 or 1; and

q is independently in each occurrence a number of from 0 to 1.

4. A method according to claim 1 wherein the bisphenolic, phenolic, benzyl alcohol, aminophenyl or, benzylamino moieties of the capping compound contains one aromatic moiety and one aliphatic substituent on the aromatic ring which does not interfere in the reaction of the amino or hydroxyl groups with an isocyanate groups.

5. The method according to claim 4 wherein the isocyanate terminated prepolymer corresponds to one of the formulas

wherein

R 1 is independently in each occurrence a C 2-20 m valent alkyl moiety;

R 2 is independently in each occurrence a polyether chain;

R 3 is independently in each occurrence an alkylene, cycloalkylene or mixed alkylene and cycloalkylene moiety;

X is O or —NR 6 with the proviso that X is O where p is 1; and that where p is 0, X is O in at least one occurrence;

R 6 is independently in each occurrence hydrogen or alkyl;

m is independently in each occurrence a number of 1 to 6; and

n is independently in each occurrence a number of 1 or greater.

6. A composition according to claim 1 wherein the toughening composition corresponds to one of the formulas

wherein

R 1 is independently in each occurrence a C 2-20 m valent alkyl moiety;

R 2 is independently in each occurrence a polyether chain;

R 3 is independently in each occurrence an alkylene, cycloalkylene or mixed alkylene and cycloalkylene moiety, optionally containing one or more oxygen or sulfur atoms;

R 4 is a direct bond or an alkylene, carbonyl, oxygen, carboxyloxy, or amido moiety;

R 5 is independently in each occurrence an alkyl, alkenyl, alkyloxy or aryloxy moiety with the proviso that if p=1 then q=0;

X is O or —NR 6 with the proviso that X is O where p is 1; that where p is 0, X is O in at least one occurrence;

R 6 is independently in each occurrence hydrogen or alkyl;

m is independently in each occurrence a number of about 1 to about 6;

n is independently in each occurrence a number of 1 or greater;

o is independently in each occurrence 0 or 1 if p is 0, and 0 if p is 1;

p is independently in each occurrence 0 or 1; and

q is independently in each occurrence a number of from 0 to 1.

7. A method according to claim 6 wherein

R 1 is independently in each occurrence a 2 to 3 valent C 2-8 alkyl moiety;

R 2 is a polyalkylene polyether chain having a weight average molecular weight of about 400 to about 4000;

R 3 is independently in each occurrence a C 1-20 alkylene, cycloalkylene or mixed alkylene and cycloalkylene moiety;

R 4 is a C 1-20 straight or branched chain alkylene moiety;

R 5 is independently in each occurrence C 1-20 alkyl, C 2-20 alkenyl, C 1-20 alkoxy or

C- 6-20 aryloxy moiety with the proviso that where p is 0, R 5 is a C 1-20 alkyl moiety;

R 6 is independently in each occurrence hydrogen or C 1-4 alkyl moiety;

m is independently in each occurrence about 2 to about 4;

n is independently in each occurrence about 1 to about 3;

p is independently in each occurrence a number of 0 or 1 and

q is 0 or 1.

8. A method according to claim 2 wherein the adhesive demonstrates a viscosity of about 30 Pa·s to about 150 Pa·s at 45° C.

9. A method according to claim 8 wherein the adhesive is sprayed as a bead from a nozzle which is located about 3 to about 10 mm from the substrate surface.

10. A method according to claim 8 wherein the adhesive is sprayed using a pressure of about 50 to about 300 bar.

11. A method according to claim 8 wherein the adhesive is sprayed at a temperature of about 20° C. to about 65° C.

12. A method according to claim 11 wherein the adhesive is subjected to heating to a temperature at which the curing agent initiates cure of the adhesive.