Process for preparing a reinforced and reactive thermoplastic composition, and this composition
A process for preparing a reinforced and reactive thermoplastic composition having a continuous phase based on a thermoplastic polymer and dispersed therein is a discontinuous phase based on a reactive reinforcing agent that may be immiscible with the thermoplastic polymer is provided. A composition obtained by this process is also provided. The reinforcing agent is selected from the group consisting of epoxy resins, polyorganosiloxanes having SiH functional group(s), diisocyanates or polyisocyanates and mixtures thereof, comprises a grafting, a branching and/or a crosslinking, that are carried out in situ, by reactive compounding of these phases with a shear rate greater than 10 2 s −1 , of the reinforcing agent onto the chain of the thermoplastic polymer, so that the discontinuous phase is dispersed homogeneously in the continuous phase in the form of nodules having a number-average size of less than 5 μm.
1. A reactive thermoplastic composition that can be used to form a reactive system selected from the group consisting of interphase compatibilizing systems, systems for sizing fibers in composites and systems for dispersing fillers in thermoplastic phases, the composition comprising a continuous phase which is based on at least one thermoplastic polymer and dispersed in which is a discontinuous phase based on at least one reactive reinforcing chemical agent selected from the group consisting of epoxy resins, polyorganosiloxanes having SiH functional group(s), polyisocyanates and mixtures thereof, wherein this composition is free of any compatibilizing agent between said phases and comprises the product of an in situ reaction of grafting, branching and/or crosslinking, by a reactive compounding of these phases under a shear rate greater than 10 3 s −1 , of said at least one reinforcing agent onto the chain of said at least one thermoplastic polymer, so that the latter has (have), by this reaction, a grafted, branched and/or crosslinked structure, said discontinuous phase being dispersed in said continuous phase in the form of nodules having a number-average size of less than 5 μm with a maximum standard deviation of 0.5 μm.
2. The composition as claimed in claim 1 , wherein said at least one reactive reinforcing chemical agent comprises a crosslinked or non-crosslinked epoxy resin in an amount between 0.5 and 60 parts by weight per 100 parts of thermoplastic polymer(s), this epoxy resin being selected from the group consisting of bisphenol A epoxy resins, bisphenol F epoxy resins, glycol epoxy resins, brominated epoxy resins, novolac epoxy resins, phenolic epoxy resins, epoxy resins based on vinyl and/or glycidyl ether, monomers, oligomers and block polymers of these resins and mixtures thereof.
3. The composition as claimed in claim 2 , wherein it is free of any crosslinking system for said epoxy resin, which epoxy resin reacts in situ radically with said at least one thermoplastic polymer like a terminating agent.
4. The composition as claimed in claim 1 , wherein said at least one reactive reinforcing chemical agent comprises:
a polyorganosiloxane having SiH functional groups along the chain or at the chain ends, in an amount between 0.1 and 40 parts by weight per 100 parts of thermoplastic polymer(s); or
a polyisocyanate in an amount between 0.5 and 30 parts by weight per 100 parts of thermoplastic polymer(s), this polyisocyanate being selected from the group consisting of diphenylmethane-4,4′-diisocyanate (MDI), toluene-2,4-diisocyanate (TDI), hexamethylene-1,6-diisocyanate (HDI), polymethylene polyphenyl polyisocyanate (PMPPI) and mixtures thereof.
5. The composition as claimed in claim 1 , wherein:
said continuous phase is based on at least one polyether-block-amide (PEBA), said discontinuous phase being based on at least one epoxy resin; or
said continuous phase is based on a thermoplastic polyurethane (TPU), said discontinuous phase being based on;
at least one polyorganosiloxane having Sill functional group(s), or on
a polyisocyanate; or else
said continuous phase is based on a mixture of at least one polyether-block-amide (PEBA) and of a thermoplastic polyurethane (TPU), said discontinuous phase being based either on;
at least one epoxy resin optionally including an amine crosslinking system, or on
a polyisocyanate; or else wherein
said continuous phase is based on a polyamide, said discontinuous phase being based on at least one epoxy resin optionally including an amide crosslinking system.