Method for recycling polymers and product produced from said method

Abstract

The invention relates to a recycling method for obtaining a polymer from post-consumer materials, and to a material and a part consisting of polymers obtained from the recycling of used polymers.

Claims

1. A method for recycling polymers from ground post-consumer materials, the method comprising a step for extracting volatile organic compounds present within said polymers, wherein said volatile organic compounds are extracted by contacting the ground materials with a solution comprising at least a wetting agent and/or an agent for solubilizing fatty acid esters, at a temperature between 15 C. and 5 C. below the boiling point of said solution.

2. The method for recycling according to claim 1, wherein said wetting agent is an alcohol.

3. The method for recycling according to claim 2, wherein said wetting agent is a C1-C5 aliphatic alcohol.

4. The method for recycling according to claim 2, wherein the alcohol content of said solution is between 4% and 25% by volume.

5. The method for recycling according to claim 1, wherein said agent for solubilizing said fatty acid esters is an acid added to said solution so that the solution pH is greater than or equal to 2 and less than or equal to 5.

6. The method for recycling according to claim 5, wherein said acid is selected from the group of mineral acids.

7. The method for recycling according to claim 1, wherein fragments of the ground material have a thickness of less than 5 mm and have a surface area of between 1 cm.sup.2 and 4 cm.sup.2.

8. The method for recycling according to claim 1, wherein said volatile organic compounds to be extracted are molecules of molar mass less than 400 g/mol.

9. The method according to claim 1, wherein said polymers to be recycled are polyolefins (homopolymers or copolymers of olefins).

10. The method for recycling according to claim 1, wherein said extraction is carried out under atmospheric pressure.

11. The method for recycling according to claim 1, wherein said solution is in liquid state.

12. The method for recycling according to claim 1, wherein said polymer resulting from said method is the same as the polymer contained in said post-consumer material subjected to said method.

13. The material obtained from the method according to claim 1.

14. The part manufactured in the material according to claim 13.

15. The method for recycling according to claim 3, wherein the alcohol content of said solution is between 4% and 25% by volume.

16. The method for recycling according to claim 2, wherein fragments of the ground material have a thickness of less than 5 mm and have a surface area of between 1 cm.sup.2 and 4 cm.sup.2.

17. The method for recycling according to claim 2, wherein fragments of the ground material have a thickness of less than 5 mm and have a surface area of between 1 cm.sup.2 and 4 cm.sup.2.

18. The method for recycling according to claim 2, wherein said volatile organic compounds to be extracted are molecules of molar mass less than 400 g/mol.

19. The method for recycling according to claim 2, wherein said volatile organic compounds to be extracted are molecules of molar mass less than 400 g/mol.

20. The method for recycling according to claim 2, wherein said wetting agent is a C1-C3 alcohol.

21. The method for recycling according to claim 1, wherein said wetting agent is a denatured alcohol containing a mixture of C1, C2 and C3 alcohols.

22. The method for recycling according to claim 1, wherein said agent for solubilizing said fatty acid esters is an acid added to said solution so that the solution pH is between 4 and 5.

23. The method for recycling according to claim 5, wherein said acid is hydrochloric acid or sulphuric acid.

24. The method according to claim 1, wherein said polymers to be recycled is polypropylene.

Description

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

(1) FIG. 1 is a diagrammatic view of a conventional polymer recycling facility;

(2) FIG. 2 is a front view in perspective of a front bumper of a motor vehicle;

(3) FIG. 3 is a front view in perspective of a front bumper of a motor vehicle;

(4) FIG. 4 is a front view in perspective of a rear bumper of a motor vehicle;

(5) FIGS. 5-7 are representations of appearance faults;

(6) FIG. 5 is an enlarged sectional view of a crater type fault;

(7) FIG. 6 is an enlarged sectional view of a particle type fault; and

(8) FIG. 7 is an enlarged sectional view of a grain type fault.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(9) FIG. 1 shows a conventional polymer recycling facility representing the recycling steps after which the extraction method according to the invention can be implemented. The facility is designated by the general reference 10.

(10) The facility 10 is designed to recover fragments of polyethylene and polypropylene from shredded post-consumer materials 12. In the example described, the shredded post-consumer materials 12 come from a motor vehicle.

(11) Shredded motor vehicle materials consist of a mixture of shredded components of a motor vehicle, once the battery, tires and metal have been recovered.

(12) In general, shredded post-consumer materials 12 include fragments 14 of metallic materials, mineral materials, polymer materials and wood.

(13) The density of wood fragments is generally less than 1 due to the wood structure comprising cavities filled with gas.

(14) In addition, the shredded post-consumer materials 12 may also include fragments of metallic materials such as copper, this material having a density greater than 1.

(15) To separate the fragments of polyethylene and polypropylene from the other fragments, the facility 10 comprises a hammermill 16.

(16) Grinding of the shredded post-consumer materials 12 results in ground materials 28. In these ground materials 28, the dimensions of most of the fragments of polypropylene and polyethylene are greater than 80 mm while those of the other fragments are much less than 80 mm.

(17) To separate the fragments of polyethylene and polypropylene from first ground materials 28, the facility 10 also comprises a screening device 32 to screen the first ground materials 28.

(18) The screening device 32 comprises a sieve 34 whose mesh has an elementary pattern of dimension equal to 80 mm so as to recover second ground materials 36, essentially comprising the fragments of polyethylene and polypropylene of dimensions greater than 80 mm, and remove residual fragments of dimensions less than 80 mm.

(19) The second ground materials 36 may possibly include residual fragments of wood and polymers.

(20) To remove the residual fragments of wood from the second ground materials 36 by densification, the facility 10 comprises a first container 38 containing a liquid medium 40 comprising a basic solution.

(21) This basic solution is designed in particular to densify the wood by hydrolysis.

(22) The container 38 containing the liquid 40 allows the separation of a supernatant portion forming third ground materials 42 from a portion 44, which sinks, containing the densified wood fragments as well as other residual fragments of heavy materials such as, for example, polyethylene and polypropylene.

(23) The facility 10 also comprises a second container 46 containing a liquid medium 48, for cleaning the fragments of the third ground materials 42 obtained previously.

(24) In addition, to remove the foam fragments and recover the fragments of polyethylene and polypropylene in the third ground materials 42, the facility 10 further comprises means 50 for separation by ventilation.

(25) The means for separation by ventilation 50 comprise fans 52.

(26) The facility 10 further comprises a third container 54 for recovering fourth ground materials 56 comprising at least the fragments of polyethylene and polypropylene and from which the foam fragments have been removed.

(27) To convey the ground materials to the containers 38, 46 and 54, the facility 10 also comprises: an upstream conveyor belt 58 for conveying the second ground materials 36 to the first container, an intermediate conveyor belt 60 for conveying the third ground materials 42 to the second container 46, and a downstream conveyor belt 62 for conveying the fourth ground materials 56 to the third container 54.

(28) The extraction method according to the invention is preferably applied to the fourth ground materials 56. It may also be applied to the ground materials 28, 36 and 42. It may also be applied to ground materials from a recycling facility comprising variants of the equipment described with reference to FIG. 1. Some items of equipment may be removed and their order may be changed.

(29) In one embodiment of the method, the ground materials are contacted with the extraction solution for 15 minutes while stirring in order to homogenize the temperature between the liquid and solid phases. The ground materials are then dried by centrifuging. The extraction method can be repeated in several successive tanks.

(30) FIG. 2 is a perspective view of a front bumper 71 of a motor vehicle. Areas 72 and 73 correspond to the appearance areas of the front bumper 71.

(31) FIG. 3 is a perspective view of a front bumper 74 of a motor vehicle. Areas 75 and 76 correspond to the appearance areas of the front bumper 74.

(32) FIG. 4 is a perspective view of a rear bumper 77 of a motor vehicle. Areas 78 and 79 correspond to the appearance areas of the rear bumper 77.

(33) FIG. 5 is a sectional view enlarged at a scale of 30:1 of an outer portion of a painted bodywork part 81a consisting of a substrate 82a and a paint film 83a. The thickness of the paint film 83a varies between points B and C, where it is equal to 100 m. It is equal to 0 m at point A. In contrast, outside the segment [BC], the film thickness is constant. The portion of the paint film 83a located between points B and C, extending over a length of 0.6 mm, is a schematic representation of a crater type fault 84.

(34) FIG. 6 shows a sectional view enlarged at a scale of 30:1 of an outer portion of a painted bodywork part 81b consisting of a substrate 82b and a paint film 83b. The substrate 82b of this figure, unlike that of FIG. 5, does not have a straight surface. Its surface appears to be convex in the portion extending from point D to point E located next to an impurity 85. The portion of the paint film 83b extending from point E to point F, over a length of 1.8 mm, is deformed. It is a schematic representation of a particle type fault 6.

(35) FIG. 7 shows a sectional view enlarged at a scale of 75:1 of an outer portion of a painted bodywork part 81c consisting of a substrate 82c and a paint film 83c. The paint film 83c has a constant thickness of 93 m. A dust particle 87 is deposited on the last coat of the paint film 83c. This fault, extending from points F to G over a length of 0.2 mm, is a schematic representation of a grain type fault 8. The other causes of grain type faults, namely the presence of a dust particle 87 on the substrate surface or between two successive coats of the paint film 83c, creating an appearance fault by deformation of the paint film 83c, are not shown.

(36) The invention is not limited to the embodiments described above.

(37) The volatile organic compounds can be extracted by using another wetting agent and another agent for solubilizing the fatty acid esters.

(38) Also, the recycling method can be used to manufacture parts other than bodywork parts for motor vehicles and even parts for sectors other than the automotive sector.

(39) Lastly, the recycling method can be applied to polymers other than polypropylene.

(40) While the process and method herein described constitute preferred embodiments of this invention, it is to be understood that the invention is not limited to this precise process and method, and that changes may be made therein without departing from the scope of the invention which is defined in the appended claims.