Solution blending process for the fabrication of nylon6-montmorillonite nanocomposites

Abstract

In general the present disclosure relates to Nylon 6/montmorillonite clay nanocomposites with enhanced mechanical properties that have been prepared primarily by solution compounding. A major challenge in producing the Nylon 6/montmorillonite clay nanocomposites is associated with the exfoliation and dispersion of the clay particles within the polymer matrix. This disclosure presents compositions and methods for obtaining highly or fully exfoliated nylon 6/montmorillonite nanocomposites not only for organically modified clays with known compatibility with nylon 6 (Cloisite 30B), but also for clays with low/no compatibility with nylon 6 (Cloisite 15A and Na—MMT) through solution compounding.

1 . A nanocomposite comprising the reaction product of:
 nylon 6; and,   a montmorillonite clay comprising an inorganic ion or an organic surfactant with the structure of an ammonium ion (NR 4   + ), wherein R represents an alkyl or aryl group and excludes hydroxyethyl groups, wherein the clay has at more than 200 platelets/μm 2  in the nanocomposite.   
     
     
         2 . The nanocomposite of  claim 1 , wherein the inorganic ion is an ion of sodium, potassium, calcium, or magnesium. 
     
     
         3 . The nanocomposite of  claim 2 , wherein the inorganic ion is a sodium ion. 
     
     
         4 . The nanocomposite of  claim 1 , wherein the organic surfactant is dimethyl bis-hydrogenated alkyl tallow ammonium ion; benzyl, dimethyl hydrogenated alkyl tallow ammonium ion; trialkyl ammonium ion; octadecyltrimethyl ammonium ion; dioctadecyldimethyl ammonium ion; tricetadecylmethyl ammonium ion; dodecylammonium ion; hexadecylammonium ion; or distearyl dimethyl ammonium ion. 
     
     
         5 . The nanocomposite of any of  claims 1 - 4 , wherein the clay has at least 400 platelets/μm 2  in the nanocomposite. 
     
     
         6 . The nanocomposite of any of  claims 1 - 5 , wherein the clay has at least 800 platelets/μm 2  in the nanocomposite. 
     
     
         7 . A film composition comprising the nanocomposite of any of  claims 1 - 6 . 
     
     
         8 . A method for producing a nanocomposite comprising the step of:
 dissolving nylon 6 in a solvent resulting in a nylon 6/solvent solution;   dispersing a montmorillonite clay in the nylon 6/solvent solution resulting in a nylon 6/montmorillonite clay solution; and,   flushing the nylon 6/montmorillonite clay solution with a non-aqueous flushing medium that does not dissolve nylon 6, thereby removing the solvent from the nylon 6/montmorillonite clay solution and thereby resulting in a solvent-free nylon 6/montmorillonite clay nanocomposite.   
     
     
         9 . The method of  claim 8 , wherein the montmorillonite clay comprises an inorganic ion that is sodium, potassium, calcium, or magnesium. 
     
     
         10 . The method of  claim 8 , wherein the montmorillonite clay further comprises a surfactant. 
     
     
         11 . The method of any of  claims 8 - 10 , wherein the surfactant comprises an organic surfactant with the structure of an ammonium ion (NR 4   + ), wherein R represents an alkyl or aryl group. 
     
     
         12 . The method of any of  claims 8 - 11 , wherein the organic surfactant is methyl bis-2-hydroxyethyl hydrogenated alkyl tallow quaternary ammonium ion; dimethyl, bis-hydrogenated alkyl tallow ammonium ion; benzyl, dimethyl hydrogenated alkyl tallow ammonium ion; trialkyl ammonium ion; octadecyltrimethyl ammonium ion; dioctadecyldimethyl ammonium ion; tricetadecylmethyl ammonium ion; dodecylammonium ion; hexadecylammonium ion; or distearyl dimethyl ammonium ion. 
     
     
         13 . The method of any of  claims 8 - 11 , wherein the R groups of the organic surfactant exclude hydroxyethyl groups. 
     
     
         14 . The method of any of  claims 8 - 13 , wherein the solvent is acetic acid, formic acid, trichloro acetic acid, phosphoric acid, sulfuric acid, chlorophenol, m-cresol, ethylene carbonate, HMPT (Hexamethylphosphoric Triamide), or mixtures thereof. 
     
     
         15 . The method of any of  claims 8 - 14 , wherein the non-aqueous flushing medium is alcohol, ester, ether, ketone, chloroform, or a mixtures thereof. 
     
     
         16 . The method of any of  claims 8 - 15 , wherein the alcohol is methanol, ethanol, or propanol. 
     
     
         17 . The method of any of  claims 8 - 15 , wherein the ester is methyl formate, ethyl formate, methyl propionate, isobutyl propionate, ethyl propionate, methyl acetate, or ethyl acetate. 
     
     
         18 . The method of any of  claims 8 - 15 , wherein the ketone is acetone, diethyl ketone, methyl ethyl ketone, methyl propyl ketone, methyl isopropyl ketone. 
     
     
         19 . The method of any of  claims 8 - 18 , wherein the volume ratio between solvent and flushing medium is 1:5, 1:4, 1:3, 1:2, 1:1, 2:1, 3:1; 4:1 or 5:1. 
     
     
         20 . The method of any of  claims 8 - 19 , wherein the volume ratio is 1:4. 
     
     
         21 . The method of any of  claims 8 - 20 , wherein the flushing medium is flushed at a flow rate of at most 50 mL/min. 
     
     
         22 . The method of any of  claims 8 - 21 , wherein the flow rate is at least 5 mL/min.