Quick cure carbon fiber reinforced epoxy resin

Abstract

An epoxy composition including an epoxy resin, a latent amine curing agent, and a specific catalyst. Preferably, the epoxy resin includes two epoxide groups per molecule, and the latent amine curing agent is a dicyanopolyamide, most preferably, dicyandiamide. The specific catalyst is preferably 2,4-toluene bis dimethyl urea. A prepreg employing the epoxy composition of the present invention can achieve a 95% cure in about one half of the time required by a prepreg that differs only in the catalyst employed. Furthermore, prepregs employing the epoxy composition of the present invention have glass transition temperatures higher than the curing temperatures when cured at a temperature range from about 80° C. to about 150° C., enabling cured prepregs to be removed from molds without being cooled. Use of the prepregs of the present invention thus enables composite component manufacturers to substantially increase production rates without requiring the use of additional molds.

The invention in which an exclusive right is claimed is defined by the following:  
     
         1 . A resin matrix composition comprising: 
 (a) an epoxy resin having more than one epoxide group per molecule; and    (b) a catalyst consisting of 2,4-toluene bis dimethyl urea, wherein a transition glass temperature of said resin matrix composition is higher than about 140° C. after being heated to 150° C. for as little as 3 minutes.    
     
     
         2 . The resin matrix composition of  claim 1 , further comprising at least one latent curing agent.  
     
     
         3 . The resin matrix composition of  claim 2 , wherein said at least one latent amine curing agent comprises a dicyanopolyamide.  
     
     
         4 . The resin matrix composition of  claim 2 , wherein at least one latent amine curing agent comprises dicyandiamide.  
     
     
         5 . The resin matrix composition defined by  claim 1 , further comprising a thermoplastic additive.  
     
     
         6 . The resin matrix composition of  claim 5 , wherein said thermoplastic additive is at least one selected from the group consisting of polyvinylfluorides (PVFs), polymethylmethacrylates (PMMAs), polyarylethersulfones (PESs), polysulfone (PSF), polyimides (PIs), polyetherimides (PEIs), and polyethylene oxide (PEO).  
     
     
         7 . The resin matrix composition of  claim 1 , wherein said epoxy resin comprises least one epoxy resin selected from the group consisting of: bisphenol A based epoxy resins, bisphenol F based epoxy resins, epoxy phenol novolacs, trifunctional epoxy resins, tetrafunctional epoxy resins, and halogenated derivatives thereof.  
     
     
         8 . The resin matrix composition of  claim 7 , wherein said bisphenol A based epoxy resin has an epoxide equivalent weight of from about 170 to about 1400.  
     
     
         9 . The resin matrix composition of  claim 7 , wherein said bisphenol A based epoxy resin is a blend of a first, bisphenol A based epoxy resin having an epoxy equivalent in the range of from about 180 to about 195 and a second, bisphenol A based epoxy resin having an epoxy equivalent in the range of from about 1200 to about 1400, the amount and the molecular weight of said second epoxy resin being such that the blended bisphenol A based epoxy resin has a number average molecular weight in the range of from about 200 to about 300.  
     
     
         10 . The resin matrix composition of  claim 1 , wherein an amount of said catalyst ranges from about 0.5 to about 10 phr.  
     
     
         11 . The resin matrix composition of  claim 10 , wherein said amount ranges from about 2 to about 5 phr.  
     
     
         12 . The resin matrix composition of  claim 1 , wherein said composition is more than 95% cured after being heated to about 150° C. for about five minutes.  
     
     
         13 . The resin matrix composition of  claim 1 , wherein said composition is more than 95% cured after being heated to about 120° C. for about 20 minutes.  
     
     
         14 . A resin matrix composition comprising: 
 (a) an epoxy resin having more than one epoxide group per molecule; and    (b) a catalyst consisting of 2,4-toluene bis dimethyl urea, wherein a transition glass temperature of said resin matrix is higher than about 100° C. after being heated to 80° C. for as little as 5 hours.    
     
     
         15 . The resin matrix composition of  claim 14 , further comprising at least one latent curing agent.  
     
     
         16 . The resin matrix composition of  claim 15 , wherein said at least one latent amine curing agent comprises a dicyanopolyamide.  
     
     
         17 . The resin matrix composition of  claim 15 , wherein at least one latent amine curing agent comprises dicyandiamide.  
     
     
         18 . The resin matrix composition defined by  claim 14 , further comprising a thermoplastic additive.  
     
     
         19 . The resin matrix composition of  claim 18 , wherein said thermoplastic additive is at least one selected from the group consisting of polyvinylfluorides (PVFs), polymethylmethacrylates (PMMAs), polyarylethersulfones (PESs), polysulfone (PSF), polyimides (PIs), polyetherimides (PEIs), and polyethylene oxide (PEO).  
     
     
         20 . The resin matrix composition of  claim 15 , wherein said epoxy resin comprises at least one epoxy resin selected from the group consisting of: bisphenol A based epoxy resins, bisphenol F based epoxy resins, epoxy phenol novolacs, trifunctional epoxy resins, tetrafunctional epoxy resins, and halogenated derivatives thereof.  
     
     
         21 . The resin matrix composition of  claim 20 , wherein the bisphenol A based epoxy resin has an epoxide equivalent weight of from about 170 to about 1400.  
     
     
         22 . The resin matrix composition of  claim 20 , wherein the bisphenol A based epoxy resin is a blend of a first, bisphenol A based epoxy resin having an epoxy equivalent in the range of from about 180 to about 195 and a second, bisphenol A based epoxy resin having an epoxy equivalent in the range of from about 1200 to about 1400, the amount and the molecular weight of said second epoxy resin being such that the blended bisphenol A based epoxy resin has a number average molecular weight in the range of from about 200 to about 300.  
     
     
         23 . The resin matrix composition of  claim 14 , wherein an amount of said catalyst ranges from about 0.5 to about 10 phr.  
     
     
         24 . The resin matrix composition of  claim 23 , wherein said amount ranges from about 2 to about 5 phr.  
     
     
         25 . The resin matrix composition of  claim 14 , wherein a transition glass temperature thereof is higher than about 118° C. after being heated to 80° C. for 5 hours.  
     
     
         26 . An article resulting from curing the resin matrix composition of  claim 1 , said resin matrix composition further comprising a reinforcing agent.  
     
     
         27 . The article of  claim 26 , wherein said reinforcing agent comprises at least one selected from the group consisting of glass fibers, aramid fibers, and graphite fibers, and wherein said fibers comprise at least one of woven fibers, matted fibers, and unidirectional fibers.  
     
     
         28 . An adhesive film resulting from curing the resin matrix composition of  claim 1 , said resin matrix composition further comprising a supporting material.  
     
     
         29 . The adhesive film of  claim 28 , wherein said supporting material comprises at least one selected from the group consisting of polyester and nylon.  
     
     
         30 . A prepreg comprising: 
 (a) an epoxy composition including: 
 (i) an epoxy resin having more than one epoxide group per molecule; and  
 (ii) a catalyst consisting of 2,4-toluene bis dimethyl urea, wherein a transition glass temperature of said epoxy composition is higher than about 140° C. after being heated to 150° C. for as little as 3 minutes;  
   (b) a plurality of reinforcing fibers.    
     
     
         31 . The prepreg of  claim 30 , wherein said plurality of reinforcing fibers comprise at least one type of reinforcing fiber selected from the group consisting of glass fibers, aramid fibers, graphite fibers, woven fibers, matted fibers, and unidirectional fibers.  
     
     
         32 . The prepreg of  claim 30 , further comprising at least one latent curing agent.  
     
     
         33 . The prepreg of  claim 32 , wherein said at least one latent amine curing agent comprises a dicyanopolyamide.  
     
     
         34 . The prepreg of  claim 32 , wherein said at least one latent amine curing agent comprises dicyandiamide.  
     
     
         35 . The prepreg of  claim 30 , further comprising a thermoplastic additive.  
     
     
         36 . The prepreg of  claim 35 , wherein said thermoplastic additive comprises at least one thermoplastic additive selected from the group consisting of polyvinylfluorides (PVFs), polymethylmethacrylates (PMMAs), polyarylethersulfones (PESs), polysulfone (PSF), polyimides (PIs), polyetherimides (PEIs), and polyethylene oxide (PEO).  
     
     
         37 . The prepreg of  claim 30 , wherein said epoxy resin comprises at least one epoxy resin selected from the group consisting of: bisphenol A based epoxy resins, bisphenol F based epoxy resins, epoxy phenol novolacs, trifunctional epoxy resins, tetrafunctional epoxy resins, and halogenated derivatives thereof.  
     
     
         38 . The prepreg of  claim 37 , wherein the bisphenol A based epoxy resin has an epoxide equivalent weight of from about 170 to about 1400.  
     
     
         39 . The prepreg of  claim 37 , wherein the bisphenol A based epoxy resin is a blend of a first, bisphenol A based epoxy resin having an epoxy equivalent in the range of from about 180 to about 195 and a second, bisphenol A based epoxy resin having an epoxy equivalent in the range of from about 1200 to about 1400, the amount and the molecular weight of said second epoxy resin being such that the blended bisphenol A based epoxy resin has a number average molecular weight in the range of from about 200 to about 300.  
     
     
         40 . The prepreg of  claim 30 , wherein an amount of said catalyst ranges from about 0.5 to about 10 phr.  
     
     
         41 . The prepreg of  claim 40 , wherein said amount ranges from about 2 to about 5 phr.  
     
     
         42 . The prepreg of  claim 30 , wherein said prepreg is more than 95% cured after being heated to about 150° C. for less than five minutes.  
     
     
         43 . The prepreg of  claim 30 , wherein said prepreg is more than 95% cured after being heated to about 120° C. for less than 20 minutes.  
     
     
         44 . A prepreg comprising: 
 (a) an epoxy composition including: 
 (i) an epoxy resin having more than one epoxide group per molecule; and  
   (ii) a catalyst consisting of 2,4-toluene bis dimethyl urea, wherein a transition glass temperature of said epoxy composition is higher than about 100° C. after being heated to 80° C. for as short as 5 hours; and    (b) a plurality of reinforcing fibers.    
     
     
         45 . The prepreg of  claim 44 , wherein said plurality of reinforcing fibers comprise at least one type of reinforcing fiber selected from the group consisting of glass fibers, aramid fibers, graphite fibers, woven fibers, matted fibers, and unidirectional fibers  
     
     
         46 . The prepreg of  claim 44 , further comprising at least one latent curing agent.  
     
     
         47 . The prepreg of  claim 46 , wherein said at least one latent amine curing agent comprises a dicyanopolyamide.  
     
     
         48 . The prepreg of  claim 46 , wherein at least one latent amine curing agent comprises dicyandiamide.  
     
     
         49 . The prepreg defined by  claim 44 , further comprising a thermoplastic additive.  
     
     
         50 . The prepreg of  claim 49 , wherein said thermoplastic additive comprises at least one thermoplastic additive selected from the group consisting of polyvinylfluorides (PVFs), polymethylmethacrylates (PMMAs), polyarylethersulfones (PESs), polysulfone (PSF), polyimides (PIs), polyetherimides (PEIs), and polyethylene oxide (PEO).  
     
     
         51 . The prepreg of  claim 44 , wherein said epoxy resin comprises at least one epoxy resin selected from the group consisting of: bisphenol A based epoxy resins, bisphenol F based epoxy resins, epoxy phenol novolacs, trifunctional epoxy resins, tetrafunctional epoxy resins, and halogenated derivatives thereof.  
     
     
         52 . The prepreg of  claim 51 , wherein the at bisphenol A based epoxy resin has an epoxide equivalent weight of from about 170 to about 1400.  
     
     
         53 . The prepreg of  claim 51 , wherein the bisphenol A based epoxy resin is a blend of a first bisphenol A based epoxy resin having an epoxy equivalent in the range of from about 180 to about 195 and a second, bisphenol A based epoxy resin having an epoxy equivalent in the range of from about 1200 to about 1400, the amount and the molecular weight of said second epoxy resin being such that the blended bisphenol A based epoxy resin has a number average molecular weight in the range of from about 200 to about 300.  
     
     
         54 . The prepreg of  claim 44 , wherein an amount of said catalyst ranges from about 0.5 to about 10 phr.  
     
     
         55 . The prepreg of  claim 54 , wherein said amount ranges from about 2 to about 5 phr.  
     
     
         56 . The prepreg of  claim 44 , wherein a transition glass temperature thereof is higher than about 118° C. after being heated to 80° C. for 5 hours.  
     
     
         57 . A method to enable a thermosetting epoxy resin formulation to rapidly reach a 95% cure, said method comprising the steps of: 
 (a) providing an epoxy composition including an epoxy resin having more than one epoxide group per molecule, and a latent amine curing agent;    (b) mixing at least 0.5 phr of a catalyst in said epoxy composition, said catalyst reducing the time required to reach a 95% cure and consisting of 2,4-toluene bis dimethyl urea; and    (c) heating said epoxy composition with said catalyst to at 150° C. for at least 3 minutes, said catalyst substantially decreasing the time required to reach a 95% cure.    
     
     
         58 . The method of  claim 57 , wherein a glass transition temperature of the epoxy composition is from about 140° C. to greater than 150° C.  
     
     
         59 . The method of  claim 57 , wherein said epoxy composition further comprises a plurality of reinforcing fibers.