Polyamide and bioresourced reinforcement compositions having improved mechanical properties

Abstract

One subject of the present invention is a composition that combines at least one polyamide having at least one MXD entity, MXD denoting meta-xylylenediamine or a mixture of meta-xylylenediamine and of para-xylylenediamine, with a bioresourced reinforcement. The invention also relates to the conversion of these compositions, by injection moulding or extrusion, into objects that have good mechanical properties, said objects corresponding to technical application specifications such as may be found, for example, in the automotive industry, construction, sport and in electrical or electronic fields.

1 . A composition that combines at least one polyamide having at least one MXD entity, MXD denoting meta-xylylenediamine or a mixture of meta-xylylenediamine and of para-xylylenediamine, with a biobased reinforcement within the meaning of standard ASTM D6852 and, more preferentially, within the meaning of standard ASTM D6866. 
     
     
         2 . The composition as claimed in  claim 1 , characterized in that the polyamide corresponds to the formula MXD.Z, the Z entity being an aliphatic, cycloaliphatic or aromatic, C 4 -C 36  dicarboxylic acid. 
     
     
         3 . The composition as claimed in  claim 1 , characterized in that the polyamide is a copolyamide corresponding to the formula A/MXD.Z, the Z entity being an aliphatic, cycloaliphatic or aromatic, C 4 -C 36  dicarboxylic acid, and the A entity being chosen from a lactam, an α,ω-aminocarboxylic acid and the product of the reaction of an aliphatic, cycloaliphatic or aromatic, C 4 -C 36  dicarboxylic acid with an aliphatic, cycloaliphatic, arylaliphatic or aromatic, C 4 -C 36  diamine. 
     
     
         4 . The composition as claimed in  claim 2  or  3 , characterized in that the Z entity is an aliphatic dicarboxylic acid comprising at least 6, advantageously 7 and more preferentially 10 carbon atoms. 
     
     
         5 . The composition as claimed in  claim 3  or  4 , characterized in that the A entity is a lactam or an α,ω-aminocarboxylic acid comprising at least 6, and more preferentially at least 10, carbon atoms. 
     
     
         6 . The composition as claimed in  claim 5 , characterized in that the A entity is chosen from caprolactam, lactam 12, 11-aminoundecanoic acid and 12-aminododecanoic acid. 
     
     
         7 . The composition as claimed in  claim 3  or  4 , characterized in that, the A entity being the product of condensation of a diamine with a dicarboxylic acid, said diamine is an aromatic diamine, preferably meta-xylylenediamine or a mixture of meta-xylylenediamine and of para-xylylenediamine. 
     
     
         8 . The composition as claimed in any one of  claims 3  to  7 , characterized in that the molar proportion of the MXD.Z unit, in the copolyamide of formula A/MXD.Z, represents more than 25%, preferably more than 50% and more preferentially more than 65%. 
     
     
         9 . The composition as claimed in any one of  claims 1  to  8 , characterized in that the biobased reinforcement comprises at least one element chosen from plant fibers, animal fibers, biobased polymers, biobased carbon fibers and biobased carbon nanotubes. 
     
     
         10 . The composition as claimed in  claim 9 , characterized in that the plant fiber is chosen from flax, hemp, sisal, kenaf, abaca and jute. 
     
     
         11 . The composition as claimed in any one of  claims 1  to  10 , characterized in that the biobased reinforcement is in the form of a ground material, a flour, a short fiber, a long fiber, woven continuous fibers, nonwoven continuous fibers, or a mat of woven or nonwoven fibers. 
     
     
         12 . The composition as claimed in any one of  claims 1  to  11 , characterized in that it also comprises at least one second reinforcement which is not biobased, it being possible for said second reinforcement to be a carbon fiber, carbon nanotubes or glass fibers. 
     
     
         13 . The composition as claimed in  claim 12 , characterized in that the (biobased reinforcement) to (non-biobased second reinforcement) mass ratio is greater than 0.3, preferably greater than or equal to 1, and more particularly greater than or equal to 3. 
     
     
         14 . The composition as claimed in any one of  claims 1  to  13 , characterized in that the weight proportion of biobased reinforcement and, where appropriate, of non-biobased second reinforcement is between 5% and 80%, advantageously between 10% and 70%, preferably between 15% and 50%, and even more preferably between 15% and 40%, of the total weight of the composition. 
     
     
         15 . The composition as claimed in any one of  claims 1  to  14 , characterized in that it also comprises at least one second polyamide. 
     
     
         16 . The composition as claimed in  claim 15 , characterized in that the weight proportion of the second polyamide represents less than 50%, preferably less than 25%, and more particularly less than 15%, of all of the polyamides. 
     
     
         17 . The composition as claimed in any one of  claims 1  to  16 , characterized in that it also comprises at least one additive chosen from impact modifiers, processing aids, UV-stabilizers, heat-stabilizers, fire-retardants, preferably in a weight proportion representing less than 50%, advantageously less than 20%, of the total weight of the composition. 
     
     
         18 . The composition as claimed in any one of  claims 1  to  17 , characterized in that it also comprises fillers, such as talc, montmorillonite, chalk, mica and kaolin, preferably in a weight proportion representing less than 30%, and more particularly less than 20%, of the total weight of the composition. 
     
     
         19 . The composition as claimed in any one of  claims 1  to  18 , characterized in that the biobased reinforcement and, where appropriate, the non-biobased second reinforcement undergo a treatment aimed at improving their adhesion with respect to the polyamides, said treatment being chosen from:
 a chemical treatment, 
 a precoating of the reinforcement with a polymeric coupling agent, 
 a plasma treatment, 
 a mechanical or thermomechanical treatment, 
 a laser treatment, 
 a γ- or UV-irradiation. 
 
     
     
         20 . A method for producing a composite material from a composition comprising a biobased reinforcement in the form of short fibers as claimed in any one of  claims 11  to  19 , said method comprising the following steps:
 A—compounding of the biobased reinforcement and of the polyamide(s) in an extruder or a co-kneader, between 180 and 240° C., 
 B—extrusion of the rod, 
 C—granulation of the rod. 
 
     
     
         21 . A method for producing a composite material from a composition comprising a biobased reinforcement in the form of long fibers as claimed in any one of  claims 11  to  19 , said method comprising the following steps:
 A—impregnation of the biobased reinforcement in the molten polyamide(s) between 180 and 240° C. by means of a crosshead extruder, 
 B—extrusion of the rod, 
 C—granulation of the rod. 
 
     
     
         22 . A method for producing a composite material from a composition comprising a biobased reinforcement in the form of woven or nonwoven fibers as claimed in any one of  claims 11  to  19 , said method comprising the following steps:
 A—stacking of alternating biobased reinforcement and films of the polyamide(s), or rolling of biobased reinforcement multilayers alternating with a film of polyamide(s), 
 B—hot-pressing of between 180 and 240° C. 
 
     
     
         23 . A method for producing a composite material from a composition comprising a biobased reinforcement in the form of continuous fibers as claimed in any one of  claims 11  to  19 , said method comprising the following steps:
 A—preimpregnation of the biobased reinforcement in a fluidized bed of polyamide(s) by the electrostatic route and then heating in an oven brought to between 200° C. and 240° C., or in the molten polyamide(s), 
 B—filament winding, 
 C—heating in an oven brought to between 180° C. and 240° C. 
 
     
     
         24 . A method for producing a composite material from a composition comprising a biobased reinforcement in the form of woven or nonwoven fibers as claimed in any one of  claims 11  to  19 , said method comprising the following steps:
 A—preimpregnation of the biobased reinforcement, 
 B—production of sheets by hot-pressing of between 180 and 240° C. 
 
     
     
         25 . A method for producing a composite material from a composition comprising a biobased reinforcement in the form of continuous fibers as claimed in any one of  claims 11  to  19 , for producing profiles by pultrusion, said method comprising the following steps:
 A—drawing of the biobased reinforcement and continuous impregnation of the polyamide(s) in a molten state or in a fluidized bed of powder of polyamide(s), 
 B—passing through a heating fixture brought to between 180 and 240° C. giving the shape of the cross section of the profile. 
 
     
     
         26 . The use of a composition as claimed in any one of  claims 1  to  19 , for producing objects, in particular a recyclable object. 
     
     
         27 . An object obtained from a composition according to any one of  claims 1  to  19 , in particular by injection-molding, extrusion, forming, calendering, filament winding or pultrusion of such a composition. 
     
     
         28 . The use of the object as claimed in  claim 27  in the automotive field, the construction field, in the electrical or electronic field, or in the sporting goods field.