Process for the treatment of technical textiles
The present invention relates to a process for the treatment of technical textiles based on thermoplastic fibers and comprising a coating, such as, in particular, airbags, using the principle of centrifugal decanting to separate the fiber residues and the coating material. The invention also relates to a process for the manufacture of a thermoplastic composition, in particular for molding, obtained by use of the fiber residues as obtained and optionally of reinforcing fillers. The distinguishing feature of this invention is based on the preparation of the fabric devoid of coating, thus resulting in formulations with elevated mechanical performances.
1. A process for treating technical textiles, said technical textiles comprising thermoplastic fibers and a coating material and said process comprising the steps of:
a) treating said textiles so as to obtain a mixture comprising:
fibrous thermoplastic particles, and
spherical or quasispherical particles of the coating material, said particles of the coating material exhibiting a mean diameter of between 15 and 750 μm;
b) suspending the mixture obtained in step a) with an alkaline medium which makes possible the separation of the coating material and fibrous thermoplastic particles; said medium exhibiting a density between the density of the fibrous thermoplastic particles and the density of the coating material;
c) separating the coating material and the fibrous thermoplastic particles by centrifugal force; and
d) drying the fibrous thermoplastic particles.
2. The process of claim 1 , wherein the thermoplastic fibers are based on polyamide, polyolefin, polyester, and/or polyurethane.
3. The process of claim 1 wherein the coating is based on polyvinyl chloride, polyurethane, acrylic, elastomers, and/or silicone.
4. The process of claim 1 , wherein the technical textiles are airbag residues.
5. The process of claim 1 , wherein the mixture of particles of step a) is obtained by grinding the technical textiles and then micronizing the ground technical textiles.
6. The process of claim 1 , wherein the separation of step c) is carried out in a horizontal-axis centrifugal decanter.
7. The process of claim 1 , wherein the medium of step b) is an aqueous medium.
8. The process of claim 1 , wherein the alkaline medium of step b) exhibits a pH of greater than or equal to 10.
9. A process for treating airbag textiles, said airbag textiles comprising fibrous polyamide material and a silicone coating material, to recover polyamide material, said process comprising the steps of:
a) grinding and micronizing said textiles to obtain a mixture comprising polyamide particles and silicone coating particles, said silicone coating particles exhibiting a mean diameter of between 15 and 750 μm;
b) suspending the mixture obtained in step a) in an aqueous liquid medium having a pH of greater than or equal to 10 and a density between the density of the polyamide particles and the density of the silicone coating particles;
c) separating polyamide particles from silicone coating particles by centrifugal force to recover the polyamide particles; and
d) drying the recovered polyamide particles.
10. The process of claim 1 , further comprising the step of treating the fibrous thermoplastic particles recovered in step c) in order to neutralise the pH.
11. The process of claim 9 , further comprising the step of treating the polyamide particles recovered in step c) to neutralise the pH.
12. The process of claim 1 , wherein the coating material separated is coating material particles.