Method for the continuous production of a composite material profile section from thermoplastic polymer having high fluidity

A method for continuous production of a composite material profile (30) by injection-pultrusion from at least one reinforcing fabric (14) and at least one thermoplastic polymer, said method comprising:

• a) supplying a thermoplastic polymeric composition of viscosity less than or equal to 50 Pa·s and based on one or more thermoplastic polymers in the molten state and,
• b) supplying the reinforcing fabric at a temperature less than 400° C., and greater than or equal to the temperature of said thermoplastic polymeric composition in the molten state,
• c) impregnating said reinforcing fabric from stage b) with said thermoplastic polymeric composition from stage a);
• d) shaping said reinforcing fabric impregnated with said thermoplastic polymeric composition to form said profile,
• in which:
• i) said reinforcing fabric is continuously pulled with a pulling speed of at least 0.4 m.min-1 in the course of said method;
• ii) the impregnation stage c) is performed by injection of said thermoplastic polymeric composition in the molten state through the reinforcing fabric;
• iii) the reinforcing fabric impregnated with said thermoplastic polymeric composition is shaped in stage d) with a thermal profile such that:
• its surface temperature is less than the crystallization temperature of said thermoplastic polymeric composition if semi-crystalline and less than 125° C. above the glass transition temperature (Tg) of said thermoplastic polymeric composition if amorphous, and
• its core temperature is greater than the crystallization temperature of said thermoplastic polymeric composition if semi-crystalline and higher than 50° C. above the glass transition temperature (Tg) of said thermoplastic polymeric composition if amorphous;
• wherein the impregnation c) and shaping d) stages proceed in a common channel comprising successively a hot entry zone (24), a hot impregnation zone having an injection chamber (25), a thermal control zone (28) and a shaping zone (29);
• or the impregnation c) and shaping d) stages proceed in two distinct and consecutive channels, a first channel comprising successively a hot entry zone and a hot impregnation zone having an injection chamber, a second channel comprising a shaping zone;
• wherein a thermal control zone is provided between the two channels;
• said reinforcing fabric impregnated with said thermoplastic polymeric composition being cooled in the thermal control zone;
• the viscosity, in the molten state, is measured by means of a plate-plate rheometer of diameter 50 mm, with an incremental shear scan ranging from 1 to 160 s-1;
• the polymeric material to be assessed is in the form of granules, possibly of a film of thickness 150 μm;
• when the thermoplastic polymeric composition is comparable to a semi-crystalline material, it is brought to a temperature ranging from 10 to 100° C. above its melting point and the measurement is then performed;
• when the thermoplastic polymeric composition is comparable to an amorphous material, it is brought to a temperature of 100 to 250° C. above the glass transition temperature, and the measurement is then performed.