# US 9,039,951 B2 · Curable resin composition and short-cure method

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- Number: US 9,039,951 B2
- Document ID: US9039951B2
- Status: Granted
- Kind: B2
- Application number: 13/776,754
- Filed: 2013-02-26
- Published: 2013-08-29
- Granted: 2015-05-26
- Earliest claimed: 2012-02-27
- Assignees: Cytec Technology Corp.
- Applicants: Cytec Technology Corp.
- Inventors: Jonathan E. Meegan
- Web page: https://patentgrep.com/patent/US9039951B2

## CPC

- C08K 7/06: Elements
- B29C 70/48: and impregnating the reinforcements in the closed mould, e.g. resin transfer moulding [RTM] {, e.g. by vacuum}
- C08G 59/00: Polycondensates containing more than one epoxy group per molecule (low-molecular-weight polyepoxy compounds C07); Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups
- C08G 59/38: together with di-epoxy compounds
- C08G 59/50: Amines
- C08G 59/5026: {cycloaliphatic}
- C08G 59/504: {containing an atom other than nitrogen belonging to the amine group, carbon and hydrogen}
- C08G 59/56: together with other curing agents
- C08G 65/22: Cyclic ethers having at least one atom other than carbon and hydrogen outside the ring
- C08G 85/00: General processes for preparing compounds provided for in this subclass
- C08J 3/243: {Two or more independent types of crosslinking for one or more polymers}
- C08J 3/244: {Stepwise homogeneous crosslinking of one polymer with one crosslinking system, e.g. partial curing}
- C08L 63/00: Compositions of epoxy resins; Compositions of derivatives of epoxy resins
- D06M 17/04: by applying synthetic resins as adhesives
- B29K 2063/00: Use of {EP, i.e.} epoxy resins {or derivatives thereof}, as moulding material
- B29K 2105/0809: {Fabrics}
- C08J 2363/00: Characterised by the use of epoxy resins; Derivatives of epoxy resins
- Y10T 428/24994: Fiber embedded in or on the surface of a polymeric matrix
- Y10T 428/31511: Of epoxy ether
- C08K: Use of inorganic or non-macromolecular organic substances as compounding ingredients (paints, inks, varnishes, dyes, polishes, adhesives C09)
- B29C: SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING (making preforms B29B11/00; making laminated products by combining previously unconnected layers which become one product whose layers will remain together B32B37/00 - B32B41/00)
- C08G: MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08J: WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H (working, e.g. shaping, of plastics B29)
- C08L: COMPOSITIONS OF MACROMOLECULAR COMPOUNDS (compositions based on polymerisable monomers C08F, C08G; artificial filaments or fibres D01F; textile treating compositions D06)
- D06M: TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
- B29K: INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR {MOULDS, } REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

Disclosed herein is a method for utilizing the exothermic energy generated by a low temperature cure reaction to access a high-temperature cure reaction, which is otherwise energetically inaccessible at a chosen tool temperature, thereby producing a cured resin matrix with properties closely matching to those produced via high-temperature cure reactions but achieved via a short cure time and low cure temperature. Also disclosed is a short-cure resin composition containing: (a) at least one multifunctional epoxy resin having an epoxy functionality of greater than 1; (b) a hardener composition containing (i) at least one aliphatic or cycloaliphatic amine curing agent having one or more amino groups per molecule; (ii) at least one aromatic amine curing agent having one or more amino groups per molecule; and optionally, (iii) an imidazole as curing accelerator. The improved properties of this resin composition include being curable at a temperature of ≦120° C. for a time period of less than 10 minutes to achieve a degree of cure higher than that derived from the same composition with just (i) aliphatic/cycloaliphatic amine or (ii) aromatic amine in isolation.

## Claims

### Claim 1

A method of fabricating a composite structure comprising:
preparing a curable resin composition having a viscosity suitable for Resin Transfer Molding (RTM); the curable resin composition comprising:
i. at least one multifunctional epoxy resin having an epoxy functionality greater than 1;
ii. an aliphatic or cycloaliphatic amine curing agent capable of individually initiating a curing reaction of said multifunctional epoxy resin at a cure onset temperature within the range of 30° C.-100° C. and selected from the group consisting of: isophorone diamine, triethylamine, diethylamine, triethylenetetramine (TETA), and polyether amines; and
iii. an aromatic amine curing agent capable of individually initiating a curing reaction of said multifunctional epoxy resin at a cure onset temperature of 120° C. or greater and selected from the group consisting of: 3,3′-diaminodiphenylsulphone, 4,4′-diaminodiphenylsulphone, 4,4′-methylene-bis-(3-chloro-2,6-diethylaniline) (MCDEA), 4,4′-methylene-bis-(2,6-diethylaniline) (MDEA), 2,6-diethylaniline (DEA), and dianiline;
infusing a fiber preform comprised of reinforcement fibers with said curable resin composition via a Resin Transfer Molding (RTM) process; and
curing the infused fiber preform for 5 minutes or less at a temperature below said cure onset temperature of the aromatic amine curing agent to produce a cured composite structure with a degree of cure of 95% or greater.

### Claim 2 (depends on 1)

The method of claim 1, wherein the curable resin composition further comprises an imidazole as curing accelerator.

### Claim 3 (depends on 1)

The method of claim 1, wherein the cured composite structure has a cured resin matrix with a glass transition temperature (Tg) within the range of 110° C.-150° C. as measured by Differential Scanning calorimetry (DSC).

### Claim 4 (depends on 1)

The method of claim 1, wherein said fiber preform comprises a plurality of layers of dry fibers.

### Claim 5 (depends on 1)

The method of claim 1, wherein said fiber preform comprises dry fibers made of materials selected from a group consisting of: carbon, graphite, aromatic polyamide, poly(benzothiazole) and poly(benzimidazole), poly(benzoxazole) (PBO), alumina, titania, quartz, glass, aramid, polyethylene, polyester, silicon carbide, and combinations thereof.

### Claim 6 (depends on 1)

The method of claim 1, wherein the at least one multifunctional epoxy resin comprises a combination of a di-functional epoxy resin and a tri-functional or tetra-functional epoxy resin.

### Claim 7 (depends on 1)

The method of claim 1, wherein the at least one multifunctional epoxy resin is selected from a group consisting of:

### Claim 8 (depends on 1)

The method of claim 1, wherein the aliphatic or cycloaliphatic amine curing agent is isophorone diamine.