Method of using structural adhesive
First Claim
1. A one-part, curable epoxy prepolymer/polyamide system comprising:
- a. a continuous phase comprising a polar solvent system containing a polar organic liquid, said solvent system being generally incapable of dissolving an epoxy prepolymer, said polar organic liquid having a boiling point below 200°
C. under normal ambient conditions; and
, dissolved in each 100 parts by weight of said solvent system, 5 to 300 parts by weight of a polyamide having a ball and ring softening point within the range of 60°
-200°
C. and containing at least 20 mole % terminal groups which are residues of 1,4-bis-alkylamino piperazine, and, linked by amido linkages thereto, the residue of a polyfunctional carboxylic acid; and
b. a discontinuous, substantially non-settling phase dispersed uniformly throughout said continuous phase, said discontinuous phase being selected from the group consisting of solid particles of a solid epoxy prepolymer and droplets of a liquid epoxy prepolymer, said epoxy prepolymer having an epoxide equivalent weight greater than 60.
4 Assignments
0 Petitions
Accused Products
Abstract
The disclosed method for forming an epoxy adhesive-bonded joint between a plurality of substrates is particularly well suited to an assembly line operation. The method involves forming an intimate mixture of the two components of a two-part adhesive system under conditions such that substantial curing will not occur until heat and/or pressure are applied. The application of heat and/or pressure for a short period of time initiates the curing reaction which will continue to completion under substantially normal ambient conditions. The initial bond strength is sufficient to hold mated substrates together with the bond strength increasing even when the curing process is completed under normal ambient conditions. For example, substrates can be coated with an intimate mixture of a two-part system suitable for use in this invention, stored for a period of time, mated on an assembly line under cure initiation conditions, and allowed to cure at normal room temperature and atmospheric pressure. Generally, conventional epoxy resins known in the art will work in the disclosed invention. The active hydrogen-containing curing agents or coreactants used in the disclosed invention are primary-amine terminated polyamides having a ball and ring softening point of 60°-200° C.
48 Citations
21 Claims
-
1. A one-part, curable epoxy prepolymer/polyamide system comprising:
-
a. a continuous phase comprising a polar solvent system containing a polar organic liquid, said solvent system being generally incapable of dissolving an epoxy prepolymer, said polar organic liquid having a boiling point below 200°
C. under normal ambient conditions; and
, dissolved in each 100 parts by weight of said solvent system, 5 to 300 parts by weight of a polyamide having a ball and ring softening point within the range of 60°
-200°
C. and containing at least 20 mole % terminal groups which are residues of 1,4-bis-alkylamino piperazine, and, linked by amido linkages thereto, the residue of a polyfunctional carboxylic acid; andb. a discontinuous, substantially non-settling phase dispersed uniformly throughout said continuous phase, said discontinuous phase being selected from the group consisting of solid particles of a solid epoxy prepolymer and droplets of a liquid epoxy prepolymer, said epoxy prepolymer having an epoxide equivalent weight greater than 60. - View Dependent Claims (2, 3, 4)
-
-
5. A method for forming an epoxy adhesive-bonded joint between a plurality of articles coated with both parts of a two-part epoxy adhesive, said method comprising:
-
a. blending said two parts of said epoxy adhesive, one of said parts comprising an epoxide prepolymer dissolved in solvent, the other of said parts comprising a solid polyamide having a softening point within the range of 65°
-200°
C. and at least 20 mole % terminal reactive primary amine groups which are residues of 1,4-bisalkylamino piperazine, said polyamide being dissolved in a solvent, the solvents for said epoxide prepolymer and said polyamide being selected to provide a cosolvent system for both parts of said epoxy adhesive;b. coating the resulting blended, two-part epoxy adhesive onto a surface of a first said article to form a wet film; c. evaporating off said cosolvent system to provide a dry film of two-part epoxy adhesive, essentially before the dissolved polyamide and epoxide prepolymer have an opportunity to chemically interact; d. mating a second said article with the coated article with the coated article obtained in said steps (b) and (c), under heat and pressure, whereby curing of said two-part epoxy adhesive is initiated; and e. removing said heat and pressure and continuing said curing under normal ambient conditions.
-
-
6. A method for forming an epoxy adhesive-bonded joint between a plurality of substrates, comprising:
-
a. applying to at least one of said substrates a substantially uniform mixture comprising; 1. a solution comprising a solid, primary-amine terminated polyamide dissolved therein and a suitable solvent therefor, said polyamide having a ball and ring softening point within the range of 60°
-200°
C.;2. uniformly and intimately distributed through said solution, an epoxide prepolymer having an epoxide equivalent weight greater than 60;
said epoxide prepolymer being substantially unreacted with said polyamide;b. removing sufficient solvent from said solution to cause said uniform mixture to become a non-flowable material under normal ambient temperature and pressure conditions;
said non-flowable material being capable of cure initiation at temperatures above 60°
C. and being capable of continued curing at normal ambient temperatures, subsequent to such cure initiation;c. mating said plurality of substrates; d. forming a joint with the thus-mated substrates under epoxide cure initiation conditions, which conditions include applying a temperature greater than 60°
C. to said joint for more than 1 second but less than 20 minutes, whereby said polyamide is; - View Dependent Claims (8, 10, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
-
-
7. brought to a temperature above its ball and ring softening point;
-
2. forms a flowable phase reactive with said epoxide prepolymer; and 3. enters into an amine/epoxide curing reaction with said polyamide; e. removing said epoxide cure initiation conditions before said amine/epoxide curing reaction is complete, but after the strength of the joint is sufficient to permit further handling of the mated substrates; f. continuing said amine/epoxide curing reaction under substantially normal ambient pressure and temperature conditions for at least 12 hours, the continuing of said curing reaction being characterized by an increase in the tensile shear strength of said joint. - View Dependent Claims (9, 11)
-
Specification