Process for preparing a reinforced and reactive thermoplastic composition, and this composition
The invention relates to a process for preparing a reinforced and reactive thermoplastic composition having 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 agent that may be immiscible with said at least one thermoplastic polymer, and also to a composition obtained by this process. A process according to the invention for preparing this thermoplastic composition in which said at least one 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 said at least one reinforcing agent onto the chain of said at least one thermoplastic polymer, so that said discontinuous phase is dispersed homogeneously in said continuous phase in the form of nodules having a number-average size of less than 5 μm.
1. A process for preparing a reactive thermoplastic composition comprising a continuous phase based on at least one thermoplastic polymer and dispersed therein a discontinuous phase based on at least one reactive reinforcing chemical agent that may be immiscible with said at least one thermoplastic polymer and that is selected from the group consisting of epoxy resins, polyorganosiloxanes having SiH functional group(s), diisocyanates or polyisocyanates and mixtures thereof, wherein this process comprises a grafting, a branching and/or a crosslinking, that are carried out in situ, by a reactive compounding of these phases with 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 said discontinuous phase is 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 process as claimed in claim 1 , wherein this reactive compounding is carried out under a non-inert atmosphere and at a temperature at least 30° C. above the melting point of said thermoplastic polymer or that of said thermoplastic polymers which is the highest.
3. The process as claimed in claim 1 , wherein, during this reactive compounding, there is no compatibilizing agent between said phases.
4. The process as claimed in claim 1 , wherein said reactive compounding is carried out in a co-rotating twin-screw extruder, in at least one pass and with a residence time of said phases of between 1 min and 2 min, and wherein said at least one reinforcing agent is introduced into the extruder using a pump, following the introduction of said at least one thermoplastic polymer.
5. The process as claimed in claim 1 , wherein a crosslinked or non-crosslinked epoxy resin is used for said at least one reactive reinforcing chemical agent 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.
6. The process as claimed in claim 5 , wherein no crosslinking system for said epoxy resin is used, which epoxy resin reacts in situ radically with said at least one thermoplastic polymer like a terminating agent.