Benzoxazines and compositions containing the same

Abstract

A curable composition containing more than 80% by weight of a blend of benzoxazines, wherein the blend includes (A) one or more multifunctional benzoxazines and (B) a liquid, non-halogenated monofunctional benzoxazine. This composition has been found to be stable at high temperatures, e.g. 180° C.-250° C., and suitable for making composite materials using conventional techniques such as prepregging and liquid resin infusion.

What is claimed is: 
     
         1 . A curable composition comprising more than 80% by mass of a benzoxazine blend, said benzoxazine blend comprising:
 (A) a non-halogenated, benzoxazine compound in liquid form at temperature range of 20° C.-30° C. and selected from the following Structure 1   
       
         
           
           
               
               
           
         
       
       and
 (B) a multifunctional benzoxazine component comprising one or more benzoxazine compounds with functionality of 2 or greater. 
 
     
     
         2 . The curable composition of  claim 1 , wherein the mass ratio of (A) to (B) is from about 50:50 to about 10:90. 
     
     
         3 . The curable composition of  claim 1 , wherein the composition exhibits an uncured T g  of room temperature (20° C.-30° C.) or lower as measured by Differential Scanning calorimetry (DSC). 
     
     
         4 . The curable composition of  claim 1 , wherein the composition has viscosity of 5 Pa·s or less, preferably 1 Pa·s or less, at processing temperature in the range of 100° C.-150° C. 
     
     
         5 . The curable composition of  claim 1 , wherein the multifunctional benzoxazine component (B) is a di-functional benzoxazine, and the weight ratio of monofunctional benzoxazine to difunctional benzoxazine is about 30:70. 
     
     
         6 . The curable composition of  claim 1 , wherein the benzoxazine blend comprises the liquid benzoxazine compound of Structure 1 and a trifunctional benzoxazine compound, and the mass ratio of liquid benzoxazine to trifunctional benzoxazine is from about 50:50 to about 10:90. 
     
     
         7 . The curable composition of  claim 1 , wherein the multifunctional benzoxazine component (B) comprises a combination of a difunctional benzoxazine compound and a trifunctional benzoxazine compound, and the tri-functional benzoxazine compound is present in an amount of no more than 25% by weight based on the total weight of the benzoxazine blend. 
     
     
         8 . The curable composition of  claim 5 , wherein the difunctional benzoxazine compound is selected from: 
       
         
           
           
               
               
           
         
       
     
     
         9 . The curable composition of  claim 6 , wherein the trifunctional benzoxazine compound is selected from: 
       
         
           
           
               
               
           
         
       
     
     
         10 . The curable composition of  claim 1 , wherein the multifunctional benzoxazine component (B) comprises a combination of m-substituted difunctional benzoxazine compound and m-substituted trifunctional benzoxazine trifunctional benzoxazine compound, and the trifunctional benzoxazine is at maximum 15% by weight based on the total weight of the benzoxazine blend. 
     
     
         11 . The curable composition of  claim 1 , wherein the curable composition is void of or contains less than 5% by weight, based on the total weight of the composition, of any thermosettable resin selected from epoxy, cyanate ester, bismaleimide, and phenol-formaldehyde. 
     
     
         12 . The curable composition of  claim 1 , wherein the curable composition is void of any organic solvent. 
     
     
         13 . The curable composition of  claim 1 , wherein the curable composition is thermally stable a temperature in the range of about 180° C. to about 250° C. 
     
     
         14 . A continuous resin film formed from the curable composition of  claim 1 . 
     
     
         15 . A composite material comprising reinforcement fibers impregnated or infused with the curable composition of  claim 1 . 
     
     
         16 . The composite material of  claim 15 , wherein the reinforcement fibers are selected from carbon fibers, glass fibers, and aramid fibers. 
     
     
         17 . The composite material of  claim 1 , wherein the reinforcement fibers are in the form of unidirectional fibers, a fabric, or a preform comprised of an assembly of fibers or fabric plies. 
     
     
         18 . A method for forming a prepreg comprising:
 (i) forming at least one continuous resin film from the curable composition of  claim 1 ; and   (ii) pressing the continuous resin film onto a layer of reinforcement fibers with application of heat so as to impregnate the layer of reinforcement fibers.   
     
     
         19 . The method of  claim 18 , wherein the layer of reinforcement fibers is in the form of unidirectional fibers. 
     
     
         20 . A prepreg produced by the method of  claim 18 . 
     
     
         21 . A method for fabricating a composite part comprising:
 (i) providing a preform comprising an assembly of fibers or fabric plies on a mold surface;   (ii) infusing the preform with the curable composition of  claim 4 ; and   (iii) curing the infused preform.   
     
     
         22 . A curable composite part produced by infusing a fibrous preform with the curable composition of  claim 4 .