Curable compositions, processes for using such compositions to prepare composites and processes for preparing composites having superior surface finish and high fiber consolidation

Abstract

Curable compositions, such as oxazine-based ones, are useful in applications within the aerospace industry, such as for example as a thermosetting resin composition for use as a matrix resin in processes, such as resin transfer molding, vacuum assisted transfer molding, resin film infusion, prepregging and towpregging, where the composites or laminates so prepared have superior surface finish and high fiber consolidation.

1 . A resin transfer molding process, steps of which comprise:
 (a) providing a thermosetting resin composition into a closed mold containing a preform, optionally with an agent capable of expanding;   (b) exposing the interior of the mold to a first elevated temperature and elevated pressure sufficient to wet the preform with the thermosetting resin composition; and   (c) curing the thermosetting resin composition-impregnated preform within the mold at a second elevated temperature to form a resin transfer molded product, wherein the thermosetting resin composition comprises (i) a thermosetting resin comprising at least one of epoxy, episulfide, oxazine, oxazoline, cyanate ester, maleimide, nadimide, itaconimide, phenolic and thiophenolic, and wherein at least one of the thermosetting resin composition or the preform includes the agent capable of expanding.   
     
     
         2 . The resin transfer molding process of  claim 1 , wherein the thermosetting resin composition further comprises (ii) a toughener component. 
     
     
         3 . (canceled) 
     
     
         4 . The resin transfer molding process of  claim 1 , wherein the thermosetting resin composition has a viscosity in the range of 10 to 3000 centipoise at the resin injection temperature. 
     
     
         5 . The resin transfer molding process of  claim 1 , wherein the time within which the viscosity of the thermosetting resin composition increases by 100% under the process conditions is in the range of 30 minutes to 10 hours at the injection temperature. 
     
     
         6 . The resin transfer molding process of  claim 1  wherein the plurality of fabric plies or unidirectional plies comprises fibers selected from glass, carbon, aramid and ceramics. 
     
     
         7 . The resin transfer molding process of  claim 1 , wherein the agent capable of expanding is a plurality of expandable microspheres. 
     
     
         8 . A resin transfer molded product made by the process of  claim 1 =4. 
     
     
         9 . A resin transfer molding preform comprising:
 (a) a plurality of fabric plies or unidirectional plies,   (b) a heat curable binder composition, tacked to the plurality of fabric plies or unidirectional plies, wherein the heat curable binder composition comprises (i) an oxazine component, and (ii) at least one of epoxy, episulfide, oxazoline, cyanate ester, maleimide, nadimide, itaconimide, phenolic and thiophenolic, and   (c) an agent capable of expanding volume, wherein the agent is present with or in at least one of (a) or (b), respectively.   
     
     
         10 . The resin transfer molding preform of  claim 9 ,
 wherein the heat curable binder composition further comprises optionally, a spacer selected from the group consisting of particles constructed of thermoplastics, rubbers, metals, carbon, core shell, ceramics and combinations thereof.   
     
     
         11 . A vacuum assisted resin transfer molding process, steps of which comprise:
 (a) providing a preform into a mold, wherein the preform optionally includes an agent capable of expanding;   (b) providing a thermosetting resin composition into the mold under a first elevated temperature and under vacuum for a time sufficient to allow the composition to wet the preform, where the resin composition; and   (c) exposing the mold containing the composition wetted-preform to a second elevated temperature while under vacuum sufficient to cure the thermosetting resin composition-wetted preform within the mold to form a resin transfer molded product, wherein the thermosetting resin composition comprises (i) an oxazine component and (ii) at least one of epoxy, episulfide, oxazoline, cyanate ester, maleimide, nadimide, itaconimide, phenolic and thiophenolic, and wherein at least one of the preform or the thermosetting resin composition includes an agent capable of expanding.   
     
     
         12 . The vacuum assisted resin transfer molding process of  claim 11 , wherein after providing the preform a dispersing medium is provided thereover. 
     
     
         13 . The vacuum assisted resin transfer molding process of  claim 11 , wherein the thermosetting resin composition further comprises (iii) a toughener component. 
     
     
         14 . (canceled) 
     
     
         15 . The vacuum assisted resin transfer molding process of  claim 11 , wherein the thermosetting resin composition has a viscosity in the range of 10 to 2000 centipoise at transfer molding temperature. 
     
     
         16 . The vacuum assisted resin transfer molding process of  claim 11 , wherein the time within which the viscosity of the thermosetting resin composition increases by 100% under the process conditions is in the range of 30 minutes to 10 hours at the resin transfer temperature. 
     
     
         17 . The vacuum assisted resin transfer molding process of  claim 11 , wherein the preform comprises fibers selected from glass, carbon, aramid, ceramics and combinations thereof. 
     
     
         18 . A vacuum assisted resin transfer molded product made by the process of  claim 11 . 
     
     
         19 . A vacuum assisted resin transfer molding preform comprising:
 (a) a plurality of fabric plies or unidirectional plies, optionally with an agent capable of expanding and   (b) a heat curable binder composition, optionally with an agent capable of expanding, tacked to the plurality of fabric plies or unidirectional plies, wherein the heat curable binder composition comprises (i) an oxazine component and (ii) at least one of epoxy, episulfide, oxazoline, cyanate ester, maleimide, nadimide, itaconimide, phenolic and thiophenolic, and wherein at least one of the plurality of fabric plies or unidirectional plies or the heat curable binder composition includes an agent capable of expanding.   
     
     
         20 . The vacuum assisted resin transfer molding preform of  claim 19 , wherein the heat curable binder composition further comprises (ii) a toughener component. 
     
     
         21 . (canceled) 
     
     
         22 . The vacuum assisted resin transfer molding preform of  claim 19 , wherein the heat curable binder composition further comprises optionally, a spacer selected from the group consisting of particles constructed of thermoplastics, rubbers, metals, carbon, core shell, ceramics and combinations thereof. 
     
     
         23 . The vacuum assisted resin transfer molding preform of  claim 19 , wherein the plurality of fabric plies or unidirectional plies comprises fibers selected from glass, carbon, aramid, ceramics and combinations thereof. 
     
     
         24 . A resin film infusion process, steps of which comprise:
 (a) providing a preform into a closed mold containing a thermosetting resin composition in film form each of which is an agent capable of expanding;   (b) exposing the interior of the mold to a first elevated temperature and optionally vacuum, while the exterior of the mold is exposed to an elevated pressure, for a time sufficient to infuse the preform with the thermosetting resin composition; and   (c) curing the thermosetting resin composition-infused preform within the mold at a second elevated temperature to form a resin transfer molded product, wherein the thermosetting resin composition comprises (i) an oxazine component and (ii) at least one of epoxy, episulfide, oxazoline, cyanate ester, maleimide, nadimide, itaconimide, phenolic and thiophenolic, and wherein at least one of the preform or the thermosetting resin composition in film form includes an agent capable of expanding.   
     
     
         25 . The resin film infusion process of  claim 24 , wherein the thermosetting resin composition further comprises (iii) a toughener component. 
     
     
         26 . (canceled) 
     
     
         27 . The resin film infusion process of  claim 24 , wherein the thermosetting resin composition has a viscosity in the range of 10 to 5000 centipoise at the infusion temperature. 
     
     
         28 . The resin film infusion process of  claim 24 , wherein the time within which the viscosity of the thermosetting resin composition increases by 100% under the process conditions is in the range of 30 minutes to 10 hours at the infusion temperature. 
     
     
         29 . The resin film infusion process of  claim 24 , wherein the preform comprises fibers selected from glass, carbon, aramid, ceramics and combinations thereof. 
     
     
         30 . A resin film infused product made by the process of  claim 24 . 
     
     
         31 . A prepreg comprising fibers infused with a thermosetting resin composition, comprising a resin component comprising (i) an oxazine component and (ii) at least one of epoxy, episulfide, oxazine, oxazoline, cyanate ester, maleimide, nadimide, itaconimide, phenolic and thiophenolic, at least one of the fibers or the resin component includes an agent capable of expanding. 
     
     
         32 . A prepreg process comprising the steps of:
 providing a plurality of fibers;   providing a thermosetting resin composition comprising a resin component comprising (i) an oxazine component and (ii) at least one of epoxy, episulfide, oxazoline, cyanate ester, maleimide, nadimide, itaconimide, phenolic and thiophenolic;   providing an agent capable of expanding wherein at least one of the fibers or the agent capable of expanding onto or about the layer of fibers.   
     
     
         33 . The prepreg of  claim 31 , wherein the fibers are oriented in a layer. 
     
     
         34 . The prepreg of  claim 9 , wherein the fiber layer is made from unidirectional fibers. 
     
     
         35 . The prepreg of  claim 9 , wherein the fiber layer is made from woven fibers. 
     
     
         36 . A process for producing a prepreg, steps of which comprise:
 (a) providing a layer of fibers;   (b) providing a thermosetting resin composition in liquid form;   (c) passing the layer of fibers through the liquid thermosetting resin composition to infuse the layer of fibers with the thermosetting resin composition thereby forming a prepreg assembly; and   (d) removing excess thermosetting resin composition from the prepreg assembly, wherein thermosetting resin composition comprises (i) an oxazine component and (ii) at least one of epoxy, episulfide, oxazoline, cyanate ester, maleimide, nadimide, itaconimide, phenolic and thiophenolic, and wherein at least one of the layer of fibers or the thermosetting resin composition includes an agent capable of expanding.   
     
     
         37 . The process of  claim 36 , wherein the prepreg assembly is exposed to elevated temperature and pressure conditions. 
     
     
         38 . A prepreg made by the process of claim  claim 32 . 
     
     
         39 . A prepreg made by the process of claim  claim 36 . 
     
     
         40 . Cured reaction product of the prepreg of  claim 38 . 
     
     
         41 . Cured reaction product of the prepreg of  claim 39 . 
     
     
         42 . A film comprising:
 a. a release liner;   b. a resin component comprising (i) an oxazine component and (ii) at least one of epoxy, episulfide, oxazine, oxazoline, cyanate ester, maleimide, nadimide, itaconimide, phenolic and thiophenolic; and   c. an expandable agent.   
     
     
         43 . A process for improving the surface finish of and the resin consolidation in a composite or laminate part, steps of which comprise:
 a. providing a perform into a mold;   b. providing a film according to  claim 42  onto the perform disposed within the mold;   c. providing a resin into the mold;   d. subjecting the perform, film and resin to conditions appropriate to cure the resin and expand the film to form a composite or laminate part; and   e. removing the expanded film from the composite or laminate part to reveal a composite or laminate part having improving surface finish and resin consolidation.