Epoxy resin composition

1. A heat-curable epoxy resin composition, comprising:

a) a glycidyl epoxy resin; and

b) an impact modifier that is selected from the group consisting of: a polyesteramide, a copolymer formed from a polyester and polyamide, a polyurethane, or a polyurethane formed from a polyester;

wherein:

i) the ester-containing portion of the impact modifier consists of:

1) a residue from a dimer fatty diol; or at least one acid residue selected from the group consisting of: a dimer fatty acid and a non-dimeric fatty acid; and

2) at least one diol residue selected from the group consisting of: a polyol having molecular weight of between 50 and 200 and a dimer fatty diol;

provided that the ester-containing portion of the impact modifier contains a residue from at least one of the following: the dimer fatty acid, the dimer fatty diol, or both;

ii) the composition phase separates upon curing to form phase-separated domains and/or particles comprising the impact modifier; and

iii) the weight ratio of epoxy resin:impact modifier is in the range from 1.5 to 20:1.

2. The composition of claim 1 , wherein the impact modifier is a polyester.

3. The composition of claim 1 , wherein the impact modifier is a polyesteramide.

4. The composition of claim 1 , wherein the impact modifier is a copolymer formed from a polyester and polyamide.

5. The composition of claim 1 , wherein the impact modifier is a polyurethane formed from a polyester.

6. A heat-curable epoxy resin composition, comprising:

a) a glycidyl epoxy resin; and

b) a polyester impact modifier, consisting of:

1) at least one acid residue selected from the group consisting of: a dimer fatty acid and a non-dimeric fatty acid; and

2) at least one diol residue selected from the group consisting of: a polyol having a molecular weight of between 50 and 200 and a dimer fatty diol;

provided that the polyester impact modifier contains a residue from at least one of the following: the dimer fatty acid, the dimer fatty diol, or both;

wherein:

i) the composition phase separates upon curing to form phase-separated domains and/or particles comprising the impact modifier; and

ii) the weight ratio of epoxy resin:impact modifier is in the range from 1.5 to 20:1.

7. The composition of claim 6 , wherein the polyester is formed from dimer fatty acids, adipic acid, and at least one diol having a molecular weight in the range from 50 to 200.

8. The composition of claim 6 , wherein the impact modifier comprises in the range from 15 to 50% by weight of dimer fatty acid and/or dimer fatty diol residues.

9. The composition of claim 6 , wherein the weight ratio of epoxy resin:impact modifier is in the range from 1.5 to 10:1.

10. The composition of claim 6 , comprising in the range from 10 to 50% by weight of impact modifier.

11. The composition of claim 6 , comprising in the range from 4 to 20% by weight of dimer fatty acid and/or dimer fatty diol residues.

12. The composition of claim 6 , comprising a reaction product of an epoxy resin and a prepolymer wherein the prepolymer comprises the reaction product of an epoxy resin and the oligomeric and/or polymeric impact modifier.

13. The composition of claim 12 , wherein the prepolymer comprises in the range from 20 to 60% by weight of impact modifier.

14. The composition of claim 6 , wherein said polyols comprise: pentaerythritol; glycerol; trimethylolpropane; ethylene glycol; diethylene glycol; 1,3-propylene glycol; dipropylene glycol; 1,4-butylene glycol; 1,6-hexylene glycol; neopentyl glycol; 3-methyl pentane glycol; 1,2-propylene glycol; 1,4-bis(hydroxymethyl)cyclohexane; or (1,4-cyclohexane-dimethanol).

15. The composition of claim 14 , wherein said polyols comprise: ethylene glycol; diethylene glycol; 1,4-butylene glycol; 1,6-hexylene glycol; or neopentyl glycol.

16. The composition of claim 14 , wherein said polyols comprise: 1,4-butylene glycol; 1,6-hexylene glycol; or neopentyl glycol.

17. The composition of claim 14 , wherein the polyester is formed from dimer fatty acids and adipic acid.

18. The composition of claim 17 , wherein said polyester comprises polyol residues derived from polyols selected from the group consisting of 1,4-butylene glycol, 1,6-hexylene glycol and neopentyl glycol.

19. The composition of claim 6 , wherein the polyester impact modifier comprises a ratio of dimer fatty acid residues to non-dimeric fatty acid residues in the range from 30 to 70%:30 to 70% by weight of the total dicarboxylic acids.

20. The composition of claim 19 , wherein the impact modifier is formed from dimer fatty acids, adipic acid, and at least one diol having a molecular weight in the range from 50 to 200.

21. The composition of claim 20 , wherein said polyester comprises polyol residues derived from polyols selected from the group consisting of 1,4-butylene glycol, 1,6-hexylene glycol and neopentyl glycol.

22. A heat-curable electronic assembly adhesive composition comprising the heat-curable epoxy resin composition according to claim 6 .

23. A method of forming a heat-curable epoxy resin composition comprising the heat-curable epoxy resin composition according to claim 6 , wherein the method comprises:

a) reacting the impact modifier with a first epoxy resin to form a prepolymer, and

b) mixing the prepolymer with a second epoxy resin.

24. The method of claim 23 , wherein the molecular weight of the first epoxy resin is less than the molecular weight of the second epoxy resin.

25. A method of assembling components, comprising:

a) interposing a heat-curable epoxy resin adhesive composition between respective surfaces of the components; and

b) curing said composition with the components in contact therewith, said adhesive composition comprising the heat-curable epoxy resin composition according to claim 6 .

26. A cured epoxy resin composition comprising a reaction product of:

a) a glycidyl epoxy resin; and

b) an impact modifier that is selected from the group consisting of: a polyesteramide, a copolymer formed from a polyester and polyamide, a polyurethane, or a polyurethane formed from a polyester;

wherein:

i) the ester-containing portion of the impact modifier consists of:

1) at least one acid residue selected from the group consisting of: a dimer fatty acid and a non-dimeric fatty acid; and

2) at least one diol residue selected from the group consisting of: a polyol having molecular weight of between 50 and 200 and a dimer fatty diol;

provided that the ester-containing portion of the impact modifier contains a residue from at least one of the following: the dimer fatty acid, the dimer fatty diol, or both;

ii) the cured resin composition comprises phase-separated domains and/or particles comprising the impact modifier; and

iii) the weight ratio of epoxy resin:impact modifier is in the range from 1.5 to 20:1.

27. The composition of claim 26 , wherein the impact modifier is a polyurethane.

28. The composition of claim 26 , wherein the impact modifier is a polyesteramide, a copolymer formed from a polyester and polyamide, or a polyurethane formed from a polyester.

29. A cured epoxy resin composition comprising a reaction product of:

a) a glycidyl epoxy resin; and

b) a polyester impact modifier, consisting of:

1) at least one acid residue selected from the group consisting of: a dimer fatty acid and a non-dimeric fatty acid; and

2) at least one diol residue selected from the group consisting of: a polyol having a molecular weight of between 50 and 200 and a dimer fatty diol;

provided that the polyester impact modifier contains a residue from at least one of the following: the dimer fatty acid, the dimer fatty diol, or both;

wherein:

i) said composition comprises phase-separated domains and/or particles comprising the impact modifier; and

ii) the weight ratio of epoxy resin:impact modifier is in the range from 1.5 to 20:1.

30. The composition of claim 29 , wherein the domains and/or particles have a mean particle diameter in the range from 0.4 to 7 μm.

31. The composition of claim 29 , wherein the domains and/or particles have a mean aspect ratio in the range from 0.6 to 1.4:1.

32. The composition of claim 29 , wherein less than 25% by number of domains and/or particles have a particle diameter of less than 0.5 μm.

33. The composition of claim 29 , wherein less than 20% by number of domains and/or particles have a particle diameter of greater than 5 μm.

34. The composition of claim 29 , wherein the interfacial work of adhesion (Ga) is greater than 70 Jm −2 .

35. The composition of claim 29 , wherein the essential work of fracture is in the range from 12 to 18 kJm −2 .

36. The composition of claim 29 , wherein the domains and/or particles have an aspect ratio in the range from 0.7 to 1.3:1 and a mean particle diameter in the range from 0.8 to 5 μm.

37. The composition of claim 36 , wherein at least 60% by number of the domains and/or particles have a particle diameter in the range from 0.8 to 5 μm.

38. The composition of claim 36 , wherein less than 25% by number of domains and/or particles have a particle diameter of less than 0.5 μm.

39. The composition of claim 36 , wherein less than 20% by number of domains and/or particles have a particle diameter of greater than 5 μm.

40. The composition of claim 29 , wherein said polyols comprise: pentaerythritol; glycerol; trimethylolpropane; ethylene glycol; diethylene glycol; 1,3-propylene glycol; dipropylene glycol; 1,4-butylene glycol; 1,6-hexylene glycol; neopentyl glycol; 3-methyl pentane glycol; 1,2-propylene glycol; 1,4-bis(hydroxymethyl)cyclohexane; or (1,4-cyclohexane-dimethanol).

41. The composition of claim 40 , wherein said polyols comprise: ethylene glycol; diethylene glycol; 1,4-butylene glycol; 1,6-hexylene glycol; or neopentyl glycol.

42. The composition of claim 40 , wherein said polyols comprise: 1,4-butylene glycol; 1,6-hexylene glycol; or neopentyl glycol.

43. A circuit board comprising a chip or die bonded by the cured epoxy resin composition according to claim 29 .

44. A prepolymer comprising a reaction product of:

a) 40 to 80 wt. % of an epoxy resin; and

b) 20 to 60 wt. % of a polyester impact modifier, consisting of:

1) at least one acid residue selected from the group consisting of: a dimer fatty acid and a non-dimeric fatty acid; and

2) at least one diol residue selected from the group consisting of: a polyol having a molecular weight of between 50 and 200 and a dimer fatty diol;

provided that the polyester impact modifier contains in the range of 15 to 50 wt. % of a residue from at least one of the following: the dimer fatty acid, the dimer fatty diol, or both.