Structural adhesives

Patent metadata

Field	Value
Publication number	US-9394468-B2
Application number	US-201213985399-A
Country	US
Kind code	B2
Filing date	Feb 15, 2012
Priority date	Feb 15, 2011
Publication date	Jul 19, 2016
Grant date	Jul 19, 2016

Abstract

A thermohardenable structural adhesive material that upon curing has an elongation at break of at least 10% and has a glass transition temperature (Tg) of 80° C. or higher and is useful as a structural adhesive in automobiles to reduce the deformation of bonds particularly during accidents, the adhesive is dry to the touch at ambient temperature and can be melt processed at temperature below that at which thermohardening occurs. The adhesives are useful in applications requiring a combination of high strain to failure, glass transition temperature more than 80° C., high stiffness and high strength. This combination is of particular interest in the aerospace and automotive industries.

First claim

The invention claimed is:

1. A thermohardenable structural adhesive material including an epoxy resin, a thermoplastic modifier, from 2% to 50% by weight flexibilizer, an impact modifier, and a curing agent that upon curing has an elongation at break of at least 10% and has a glass transition temperature (Tg) of 80° C. or higher;
wherein the flexibilizer includes a hydroxy terminated polyurethane polymer, polyvinyl butyral, a polyamide, a polymer that is an amine modified epoxy resin, or an epoxidized polysulfide;
wherein the thermoplastic modifier is a phenoxy resin; and
wherein the impact modifier comprises an epoxy adduct of a carboxy terminated butadiene rubber.

2. An adhesive according to claim 1 in which the elongation at break of the cured adhesive is at least 15% and preferably at least 20%.

3. An adhesive according to claim 1 in which the stiffness of the cured adhesive is at least 100 MPa and the lap shear is at least 7 MPa.

4. An adhesive according to claim 1 , comprising a solid which is non tacky to the touch at ambient temperature.

5. An adhesive according to claim 1 , which is processed at an elevated temperature that is below a hardening temperature.

6. An adhesive according to claim 1 , wherein the impact modifier comprises a core/shell material.

7. An adhesive according to claim 1 , including a blowing agent that is heat activated at a temperature above that at which the adhesive can be melt processed.

8. An adhesive according to claim 1 having a cure temperature of from 120° C. to 250° C.

9. An adhesive according to claim 1 which is melt processable at a temperature in the range 80° C. to 120° C.

10. An adhesive composition according to claim 1 comprising:
i. from 10% to 50% by weight epoxy resin;
ii. from 10% to 30% by weight thermoplastic modifier,
iii. from 2% to 10% by weight curing agent;
iv. from 2% to 50% by weight flexibilizer;
v. from 5% to 40% by weight impact modifier,
vi. from 0% to 25% by weight filler; and

optionally containing a blowing agent.

Assignees

• Czaplicki Michael
• Miller Ira
• Duclos Vincent
• Zephyros Inc

Inventors

• Czaplicki Michael
• Miller Ira
• Duclos Vincent

Classifications

• C08L71/12

  Polyphenylene oxides · CPC title

• C09J177/00

  Adhesives based on polyamides obtained by reactions forming a carboxylic amide link in the main chain (based on polyhydrazides C09J179/06; based on polyamide-imides C09J179/08); Adhesives based on derivatives of such polymers · CPC title

• C08G2650/56

  Polyhydroxyethers, e.g. phenoxy resins · CPC title

• C09J163/00 Primary

  Adhesives based on epoxy resins; Adhesives based on derivatives of epoxy resins · CPC title

• C09J159/00

  Adhesives based on polyacetals; Adhesives based on derivatives of polyacetals · CPC title