Impact strength improving agent for epoxy resin compositions

Patent metadata

Field	Value
Publication number	US-9796809-B2
Application number	US-74345608-A
Country	US
Kind code	B2
Filing date	Nov 21, 2008
Priority date	Nov 21, 2007
Publication date	Oct 24, 2017
Grant date	Oct 24, 2017

Abstract

The present invention relates to a butadiene/acrylonitrile copolymer CTBN, modified by epoxy solid resin and terminated by carboxyl groups, the terminal epoxy groups thereof also having optionally been reacted. A polymer of this type is used in particular as an impact strength improving agent in epoxy resin compositions and has proven to be particularly advantageous for gluing on or of metal surfaces. It results in a significant reduction of the infiltration with corrosion, which in turn ensures a long-lived adhesive bond.

First claim

The invention claimed is:

1. A mixture of polymers, wherein the mixture of polymers comprises at least one polymer of the formula (I)

in which R 1 is a divalent radical of a carboxyl-terminated butadiene/acrylonitrile copolymer CTBN after removal of the terminal carboxyl groups;
one of R 2 or R 3 is a divalent radical of a bisphenol A-based solid epoxy resin after removal of the terminal glycidyl ether groups, and the other one of R 2 or R 3 is radical of a liquid resin having the formula:

wherein z is 0.2-0.7,

after removal of the terminal glycidyl ether groups;
R 4 is a radical of bisphenol A;
R 5 is in each case a hydrogen atom; and
m has a value of 0 or 1, and n has a value of 1 or 2,with the proviso that (m+n) =2.

2. The mixture of polymers as claimed in claim 1 , wherein R 1 has the formula (IV)

in which the dashed lines represent the bonding sites of the two carboxyl groups;
a is the structural element which originates from acrylonitrile and b and c are the structural elements which originate from butadiene;
R 10 is a straight-chain or branched alkylene radical having 1 to 6 C atoms, which is optionally substituted by unsaturated groups;
q has a value of from 40 to 100;
s has a value of from 0.05 to 0.3;
t has a value of from 0.5 to 0.8;
u has a value of from 0.1 to 0.2;
with the proviso that (s+t+u) =1.

3. The mixture of polymers as claimed in claim 2 , wherein
q has a value of from 52 to 66;
s has a value of from 0.1 to 0.25;
t has a value of from 0.6 to 0.7;
u has a value of from 0.13 to 0.15;
with the proviso that (s+t+u) =1.

4. The mixture of polymers as claimed in claim 1 , wherein in the mixture of polymers, in at least one polymer, n is 2.

5. The mixture of polymers as claimed in claim 1 , wherein the mixture of polymers is solid at room temperature.

6. The mixture of polymers as claimed in claim 1 , wherein, in the mixture of polymers, in at least one polymer, m is 1.

7. The mixture of polymers as claimed in claim 1 , wherein
the divalent radical of the bisphenol A-based solid epoxy resin is a divalent radical of the formula (II)

wherein p has a value of ≧2, and X is a divalent radical of bisphenol A after removal of the hydroxyl groups.

8. A mixture of polymers formed by reacting at least one carboxyl-terminated butadiene/acrylonitrile copolymer CTBN, at least one bisphenol A-based solid epoxy resin having terminal glycidyl ether groups, a liquid resin having the following formula, and bisphenol A

wherein z is 0.2-0.7, in which the molar ratio of the epoxide groups of the solid epoxy resin and the liquid resin to the carboxyl groups of the butadiene/acrylonitrile copolymer CTBN is ≧2:1.

9. A process for the preparation of the mixture of polymers as claimed in claim 1 by reacting a carboxyl-terminated polymer of the formula (V) with a solid epoxy resin of the formula (VI), a liquid resin of the formula (VIII) and bisphenol A

wherein z is 0.2-0.7, in which the molar ratio of the epoxide groups of the solid epoxy resin and the liquid resin to the carboxyl groups of the butadiene/acrylonitrile copolymer CTBN is ≧2:1.

10. A polymer matrix comprising the mixture of polymers as claimed in claim 1 as an impact strength improver.

11. The polymer matrix as claimed in claim 10 , wherein the polymer matrix is an epoxy resin matrix.

12. A composition comprising
a) the mixture of polymers as claimed in claim 1 ;
b) at least one solid epoxy resin EP; and
c) at least one curing agent H for epoxy resins.

13. The composition as claimed in claim 12 , wherein the solid epoxy resin EP can be prepared by reacting compounds of the formula HO—X—OH with epichlorohydrin and/or 2-methylepichlorohydrin,
in which X in each case is a divalent radical of a diphenol after removal of the hydroxyl groups.

14. The composition as claimed in claim 12 , wherein the curing agent H for epoxy resins is activated by elevated temperature.

15. The composition as claimed in claim 12 , wherein the curing agent H for epoxy resins contains dicyandiamide.

16. The composition as claimed in claim 12 , wherein the composition additionally comprises at least one solid toughness improver.

17. The composition as claimed in claim 12 , wherein the composition additionally contains further constituents selected from the group consisting of blowing agent, filler, unreactive thermoplastic polymers, catalysts, reactive diluents, heat and/or light stabilizers, thixotropic agent, plasticizer, solvent, dyes and pigments.

18. The composition as claimed in claim 12 , wherein the composition is a structural adhesive and/or a foamable, heat-curing composition for reinforcement in cavities of structural components and reinforcing elements.

Assignees

• Frick Karsten
• Finter Jurgen
• Gerber Ulrich
• Meier Yves
• Clifford Jeannette
• Sika Tech Ag

Inventors

• Frick Karsten
• Finter Jurgen
• Gerber Ulrich
• Meier Yves
• Clifford Jeannette

Classifications

• C08G59/4253 Primary

  Rubbers · CPC title