EP4051733A1 - Polymer matrix made from pet for electric wires - Google Patents

Abstract

The invention relates to a polymer matrix comprising: 50 to 80%, preferably 64 to 73%, of PET; 18 to 50%, preferably 20 to 28%, of a polyolefin mixture; 0.1 to 15%, preferably 0.5 to 7%, of at least one flame-retardant additive; 0 to 2%, preferably 0.2 to 1%, of at least one antioxidant agent; 0 to 2%, preferably 0.2 to 1%, of at least one cross-linking promoter; 0 to 2%, preferably 0.2 to 1%, of at least one anti-hydrolysis agent, the percentages being by weight of the total weight of the matrix; and the use of same for manufacturing electric wires.

Description

Description

Title: PET-based polymer matrix for electrical wires

Technical area

The invention relates to a polymeric material suitable for use as an insulator for electric cables, in particular for the automotive industry.

Prior art

[0002] Automobiles contain more and more electric cables, which are subjected to very significant constraints, in particular temperature and oxidation. Moreover, to limit the consumption of automobiles and the impact on the environment, manufacturers are seeking to reduce the weight of the various materials constituting the vehicles. To this end, they notably reduced the section of the electrical conductors, the copper strands. Conventionally, these strands have a section of the order of 0.35mm ² , or even of the order of 0.13mm ² .

[0003] These strands are covered with an insulating material, conventionally based on PVC, and must resist fire and abrasion while being flexible. In particular, they must meet the criteria set by the ISO 6722 standard, in particular with regard to:

- high temperature pressure

- abrasion

- low temperature winding

- long-term thermal aging, i.e. 3000h.

[0004] These insulating materials generally composed of PVC as a mixture or of thermoplastic or crosslinked polyolefins have satisfactory characteristics of resistance to various stresses. In the case of PVC compounds, these insulating materials require the presence of plasticizers. [0005] However, the use of this type of insulation poses a problem during the connectorization of the cables which is generally carried out by ultrasonic welding. The efficiency of this weld can be affected by the presence of certain fatty additives in the composition of the insulating material which migrate to the surface of the copper.

[0006] During extrusion and / or welding, the PVC is heated to temperatures of the order of 190 ° C and the plasticizers it contains, in particular liquid plasticizers of the phthalate or trimellitate type, are released and disturb the frictional properties of the conductors between them, which reduces the quality of the weld.

[0007] There therefore remains a need for manufacturers to obtain a polymeric material suitable for use as an insulator for electric cables which meet the ISO 6722 type 2 and 3 standard (operating temperature of 105 ° C and 125 ° C respectively for 3000 hours) without affecting the connectorisation.

[0008] Alternatives to replace the use of PVC for automotive wiring have been developed.

[0009] For example, document WO 99 / 30330A1 describes an electric wire consisting of a conductive metal wire around which is extruded a polymer alloy comprising in particular polybutylene terephthalate (PBT). PBT is conventionally used to form the polymeric matrix of insulators for electric cables. The properties linked to the crystalline structure of PBT are known in particular to induce a barrier effect to small molecules, allowing the insulation made up from a polymer matrix comprising PBT, to ensure good resistance to hydrolysis. .

However, these solutions require the use of virgin plastics and do not allow the use of recycled plastics.

Global plastic production in 2016 is around 396 million tonnes and continues to increase, especially for packaging functions with the risk of scattering waste in nature. The collection and recycling of these materials is a solution to reducing the emission of waste into nature. According to Roland Geyer participating in an opinion given at the University of Georgia on plastic waste, the average recycling rate in Europe (one of the highest in the world) is only 26%.

[0012] There is therefore a need to develop insulators capable of exhibiting good physical properties in accordance with environmental issues.

summary

The Applicant has developed, after extensive research, a polymer matrix mainly comprising polyethylene terephthalate PET. This die can be used in the manufacture of electric cables, in particular for the automobile.

The present invention therefore relates to a polymer matrix comprising:

- 50 to 80%, preferably 64 to 73% of PET;

- 18 to 50%, preferably 20 to 28% of a mixture of polyolefins;

- 0.1 to 15%, preferably from 0.2 to 7% of at least one flame retardant additive;

- 0 to 2%, preferably 0.2 to 1% of at least one antioxidant;

- 0 to 2%, preferably from 0.2 to 1% of at least one crosslinking promoter,

- 0 to 2%, preferably from 0.2 to 1% of at least one anti-hydrolysis agent, the PET being predominantly recycled PET, the percentages being by weight of the total weight of the matrix.

In the present invention by "predominantly recycled PET" is meant that more than 50% by weight, preferably more than 75% by weight, and more preferably still more than 80% by weight of the PET used in the composition is recycled PET. Advantageously, all of the PET used in the matrix is recycled PET.

[0017] The use of recycled PET makes it possible to limit the impacts associated with plastic-based litter on the environment.

Advantageously, the recycled PET can be obtained from unrefined recycled materials.

The recycled PET of the polymer matrix comes in particular from food packaging. In fact, PET, which is mainly used for the manufacture in particular of soda or mineral water bottles, benefits from a well-established collection and recycling channel, and allows the production of food-grade rPET (recycled PET) for the manufacture of new bottles. Colored recycled PET, which cannot be used for the manufacture of transparent bottles, is also used to manufacture non-food products such as textile or industrial fibers. Thus, according to one embodiment of the invention, the recycled PET comes from transparent plastic bottles, more particularly from colored plastic bottles. The bottles are first crushed and washed to form flakes of varying shapes, then the PET is isolated from the other constituents of the containers. The flakes are extruded to form amorphous granules. This step makes it possible to extract contaminants such as cardboard, or labeling residues. At the end of this step, the unrefined recycled PET, also called amorphous recycled PET, is obtained. The amorphous granules can then be heated at 200 ° C under vacuum for 8 hours. This operation allows the extraction of low molecular weight components and restores the food character to the recycled PET commonly called rPET. It also makes it possible to extract the residual water formed by the transesterification reaction between the heated compounds, which moreover has the consequence of increasing the viscosity of the polymer. According to the invention, one can use both amorphous or crystalline PET granules or even flakes from the first sorting. From an environmental and economic point of view, it is advantageous to use amorphous PET granules or even flakes sorted by color or advantageously flakes of different colors, in particular from white, green or red bottles.

In addition, the fact that the base materials can be unrefined by long-term heating, therefore makes it possible to reduce the stages of transformation of said materials to form the polymer matrix, and therefore to further reduce the economic and environmental impact of manufacturing process.

The amount of PET is 50 to 80%, preferably 64 to 73%. Below 50% of PET, the characteristics of resistance to aging in particular are not satisfactory. Above 80%, the material formed from the polymer matrix is too rigid and does not allow use as insulation for electric cables.

In a particular embodiment, the mixture of polyolefins comprises at least one polar polyolefin and optionally one nonpolar polyolefin. The polar polyolefin can be chosen from polar polymers containing polymerized or grafted groups such as maleic anhydride; glycidyl methacrylate,; methyl, ethyl, butyl and hexyl acrylates; acrylic acid and its salts; vinyl acetate; an ethylene / methyl acrylate copolymer; an ethylene / butyl acrylate copolymer; an ethylene / methyl acrylate / glycidyl methacrylate terpolymer; and their mixtures.

When it is present, the nonpolar polyolefin is in a minority amount relative to the polar polyolefin (s), that is to say it represents less than 50% by weight of the total weight of the mixture polyolefins. This nonpolar polyolefin is chosen from polypropylene, polyethylene, methylpentene, polybutene, ethylene propylene diene, and mixtures thereof. The presence of polyolefins in the polymeric matrix makes it possible to give the matrix sufficient flexibility necessary for the application in cabling which could not be obtained with PET alone.

The amount of polyolefin mixture is 18 to 50%, preferably 20 to 28%. Below 18%, the plasticization effect is not sufficient and above 50% the abrasion resistance is not satisfactory for use as insulation for electric cables with small cross sections. copper.

Advantageously, the flame retardant additive of the polymer matrix is chosen from bromine, antimony, a brominated compound, an antimony compound or their mixtures, preferably antimony trioxide and decabromodiphenylethane.

[0028] The amount of flame retardant additive is 0.1 to 15%, preferably 0.2 to 7%. This dosage is optimized to minimize the technical and economic impact on the formulation. Below 0.1% the fire resistance would be insufficient for automotive wiring applications and beyond 15% no additional benefit is provided.

The antioxidant agent of the polymer matrix can be any antioxidant agent used in polymers. By way of examples, it can be chosen from pentaerythritol tetrakis (3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate), 2 ', 3-bis [3- [3,5- di-tert-butyl-4-hydroxyphenyl] propioyl] propionohydrazide, dioctadecyl 3,3'-thiodipropionate, or a mixture thereof. The purpose of the antioxidant is to protect polyolefins from oxidation.

The polymer matrix according to the invention may contain a crosslinking agent which may be 1, 3,5-triallylisocyanurate or trimethylolpropane trimethacrylate or a mixture thereof. This crosslinking of the polyolefin phase, in the case where the cable is subjected to electrons during an additional post-extrusion process, makes it possible to reinforce the mechanical properties of the matrix at high temperature.

The anti-hydrolysis agent used in the matrix of the invention is an agent conventionally used in this field. By way of example, there may be mentioned an agent of polycarbodiimide type.

[0032] According to a particular embodiment, the polymeric matrix is free of plasticizer. By plasticizer is meant the plasticizers conventionally used with PVC, in particular phthalates and trimellitates. Unlike PVC-based insulation, the polymer matrix according to the invention does not contain plasticizer and therefore does not interfere with connectorization.

[0033] Thus, the PET-based polymer matrix according to the invention makes it possible to achieve flexibility characteristics similar to those of PVC-based matrices thanks to the combination of PET and polyolefin, without adding a plasticizer.

[0034] The absence of plasticizer in the composition improves the quality of the weld. The strength of ultrasonic welding is better than that of PVC and uniform in quality.

[0035] The present invention also relates to the use of the polymer matrix of the invention for the manufacture of insulators for electrical conductor wires.

[0036] A subject of the invention is also a cable comprising at least one electrical conductor wire covered with an insulating sheath based on the polymer matrix defined above.

The cables according to the invention are cables conventionally used for automotive wiring, which have an electrically conductive wire with a cross section ranging from 0.08 to 0.75. mm ² .

Surprisingly, although the PET is amorphous, the inventors have succeeded in obtaining an insulator based on PET having a equivalent to or better hydrolysis resistance than PBT-based insulation.

[0039] Advantageously, cables based on recycled PET have a modulus greater than 1000 MPA, which allows them to have an abrasion resistance equivalent to that of cables currently on the market. Thus, the recycled PET cables according to the invention exhibit as good performance in terms of abrasion resistance as cables formed from formulations obtained from technical materials such as PBT, PA (Polyamide) and TPEs. (thermoplastic polyester).

[0040] Cables composed of a polymeric matrix based on recycled PET exhibit high temperature aging as well as pressure resistance at high temperatures which meet the requirements of the ISO 6722 standard.

Typically, cables composed of a polymeric matrix based on recycled PET exhibit satisfactory aging properties at temperatures of 125 and 150 ° C as measured according to ISO 6722.

[0042] The absence of plasticizers within the polymer matrix of the cables of the present invention makes it possible to obtain satisfactory results in terms of flexibility. Cables composed of a polymeric matrix based on recycled PET have an elongation at break, and a winding at -40 ° C meeting the criteria required by standard ISO 62722.

The strength and flexibility characteristics of the insulating sheath described above make it possible to limit the thickness of the insulating sheath without altering its properties.

The cables are therefore thinner and the insulating sheaths are thinner, which has the consequence of considerably reducing the weight of these cables. At equal performance, a weight gain of 30% is achieved compared to the equivalent PVC insulation. [0045] In addition, the use of recycled PET makes it possible to considerably reduce the use of virgin materials to produce the insulating sheath. For example, the use of 65% recycled PET makes it possible to use only 200 g of virgin material to insulate 1 km of wire, compared to the 950 g of PVC used on average. The use of recycled PET therefore makes it possible to save 75% on the need for resources, which is a considerable economic and ecological advantage.

The invention also relates to the use of a cable as defined above for automotive wiring. Considering the weight saving that can be obtained as explained above, the cables are quite suitable to meet the objective of limiting the environmental impact.

Another object of the invention relates to a process for preparing a cable as described above comprising:

- the preparation of a polymer matrix as defined above

- the extrusion of the matrix around an electrical conductor

- And optionally the crosslinking of the polymer matrix.

The following examples are presented only for the purpose of illustration and cannot be considered as limiting.

[0049]

Examples

Different cables according to the invention were prepared by extrusion of a polymeric matrix according to the invention around a copper strand of 0.13 mm ² in section and 0.407 mm in diameter.

The cables have undergone tests listed in Table 1.

The compositions of the constituent polymeric matrix of the sheaths tested are detailed in the following Examples 1 to 6.

In the examples, the following commercial products were used: ECOPET CB TH 80: recycled PET sold by Paprec ECOFLAKES CB TH: PET in flakes sold by Paprec ECOPET CB: PET in amorphous granules sold by Paprec Irganox 1024: antioxidant sold by BASF Irganox 1010: antioxidant sold by BASF.

[0054]

Example 1

A cable was prepared by extrusion around a copper strand of a polymer matrix having the following composition:

-64.46% by weight of ECOFLAKES CB TH,

-23.02% by weight of ethylene methyl acrylate copolymer (having a methyl acrylate content of 24% by weight),

-4.60% by weight of ethylene / methyl acrylate / / glycidyl methacrylate (67/25/8) terpolymer,

-2.30% by weight of antimony trioxide,

-4.60% by weight of decabromodiphenylethane,

-0.09% by weight of Irganox 1024,

-0.46% by weight of Irganox 1010,

-0.46% by weight of dioctadecyl 3,3'-thiodipropionate.

The extrusion was carried out so as to obtain the sheath thickness (from the polymer matrix) mentioned in Table 1. This thickness is expressed by the outside diameter of the cable.

The following characteristics were determined on the cable according to the ISO6722-1-2011 (E) standard:

- Resistance to flame propagation;

- abrasion resistance at 4N;

- rupture during elongation according to standard NF EN 60811-501,

- Pressure resistance at high temperature

- resistance to hydrolysis and electrolysis

- winding at low temperature:

- Thermal aging at 125 ° C for 3000h. The results of these tests are presented in Table 1 with the specific conditions and / or the target values in the first column.

[0059]

Example 2

In the same way as in Example 1, a cable obtained by extrusion of a polymer matrix having the following composition was prepared:

-64.46% by weight of ECOPET CB TH,

-23.02% by weight of ethylene methyl acrylate copolymer (having a methyl acrylate content of 24% by weight -4.60% by weight of ethylene / methyl acrylate / / glycidyl methacrylate (67/25/8) terpolymer ,

-2.30% by weight of antimony trioxide,

-4.60% by weight of decabromodiphenylethane,

-0.09% by weight of Irganox 1024,

-0.46% by weight of Irganox 1010,

-0.46% by weight of dioctadecyl 3,3'-thiodipropionate.

The extrusion was carried out so as to obtain the sheath thickness (from the polymer matrix) mentioned in Table 1. This thickness is expressed by the outside diameter of the cable.

The same characteristics as in Example 1 were measured on the cable.

The values obtained are collated in Table 1.

[0064]

Example 3

In the same way as in Example 1, a cable was prepared by extrusion of a polymeric matrix having the following composition:

-64.46% by weight of ECOPET CB,

-23.02% by weight of ethylene methyl acrylate copolymer 24%, -4.60% by weight of ethylene / methyl acrylate / glycidyl methacrylate (67/25/8) terpolymer,

-2.30% by weight of antimony trioxide,

-4.60% by weight of decabromodiphenylethane,

-0.09% by weight of Irganox 1024,

-0.46% by weight of Irganox 1010,

-0.46% by weight of dioctadecyl 3,3'-thiodipropionate.

[0066] The extrusion was carried out so as to obtain the sheath thickness (obtained from the polymer matrix) mentioned in Table 1. This thickness is expressed by the outside diameter of the cable.

The same characteristics as in Example 1 were measured on the cable.

The values obtained are collated in Table 1.

[0069]

Example 4

In the same way as in Example 1, a cable was prepared by extrusion of a polymeric matrix having the following composition:

-73.66% by weight of ECOFLAKES CB TH,

-13.81% by weight of ethylene methyl acrylate copolymer (having a methyl acrylate content of 24% by weight,

-4.60% by weight of ethylene / methyl acrylate / / glycidyl methacrylate (67/25/8) terpolymer,

-2.30% by weight of antimony trioxide,

-4.60% by weight of decabromodiphenylethane,

-0.09% by weight of Irganox 1024,

-0.46% by weight of Irganox 1010,

-0.46% by weight of dioctadecyl 3,3'-thiodipropionate.

The extrusion was carried out so as to obtain the sheath thickness (resulting from the polymeric matrix) mentioned in Table 1. This thickness is expressed by the outside diameter of the cable. The same characteristics as in Example 1 were measured on the cable.

The values obtained are collated in Table 1.

[0074]

Example 5

A cable was prepared by extrusion around a copper strand of a polymer matrix having the following composition:

-73.66% by weight of ECOPET CB TH,

-13.81% by weight of ethylene methyl acrylate copolymer 24%, -4.60% by weight of ethylene / methyl acrylate / glycidyl methacrylate (67/25/8) terpolymer,

-2.30% by weight of antimony trioxide,

-4.60% by weight of decabromodiphenylethane,

-0.09% by weight of Irganox 1024,

-0.46% by weight of Irganox 1010,

-0.46% by weight of dioctadecyl 3,3'-thiodipropionate.

[0076] The extrusion was carried out so as to obtain the sheath thickness (resulting from the polymer matrix) mentioned in Table 1. This thickness is expressed by the outside diameter of the cable.

The same characteristics as in Example 1 were measured on the cable.

The values obtained are collated in Table 1.

[0079]

Example 6

A cable was prepared by extrusion around a copper strand of a polymer matrix having the following composition:

-73.66% by weight of ECOPET CB,

-13.81% by weight of ethylene methyl acrylate copolymer 24%, -4.60% by weight of ethylene / methyl acrylate terpolymer / glycidyl methacrylate (67/25/8),

-2.30% by weight of antimony trioxide,

-4.60% by weight of decabromodiphenylethane,

-0.09% by weight of Irganox 1024,

5 -0.46% by weight of Irganox 1010,

-0.46% by weight of dioctadecyl 3,3'-thiodipropionate.

[0081] The extrusion was carried out so as to obtain the sheath thickness (resulting from the polymeric matrix) mentioned in Table 1. This thickness is expressed by the outside diameter of the cable.

The same characteristics as in Example 1 were measured on the cable.

The values obtained are collated in Table 1.

[Table 1]

Claims

Claims [Claim 1] A polymeric matrix comprising: - 50 to 80%, preferably 64 to 73% of PET; - 18 to 50%, preferably 20 to 28% of a mixture of polyolefins; - 0.1 to 15%, preferably 0.5 to 7% of at least one flame retardant additive; - 0 to 2%, preferably 0.2 to 1% of at least one antioxidant; - 0 to 2%, preferably 0.2 to 1% of at least one crosslinking promoter - 0 to 2%, preferably from 0.2 to 1% of at least one anti-hydrolysis agent, characterized in that the PET is predominantly recycled PET, the percentages being by weight of the total weight of the matrix. [Claim 2] Polymeric matrix according to claim 1, characterized in that the PET is recycled. [Claim 3] Polymer matrix according to claim 1 or 2, characterized in that the recycled PET comes from food packaging [Claim 4] A polymeric matrix according to any one of claims 1 to 3, wherein the polyolefin blend comprises at least one polar polyolefin; the polar polyolefin being chosen from polar polymers containing polymerized or grafted groups such as maleic anhydride; glycidyl methacrylate,; methyl, ethyl, butyl and hexyl acrylates; acrylic acid and its salts; vinyl acetate; an ethylene / methyl acrylate copolymer; an ethylene / butyl acrylate copolymer; an ethylene / methyl acrylate / glycidyl methacrylate terpolymer; and their mixtures. [Claim 5] Polymeric matrix according to any one of claims 1 to 4, further comprising, in a minor amount relative to the mixture of polyolefins, of at least one nonpolar polyolefin chosen from polypropylene, polyethylene, methylpentene, polybutene , ethylene propylene diene and mixtures thereof. [Claim 6] Polymeric matrix according to any one of claims 1 to 5, characterized in that the flame retardant additive is chosen from bromine, antimony, a bromine compound, an antimony compound or theirs. mixtures, preferably antimony trioxide and / or decabromodiphenylethane. [Claim 7] Polymeric matrix according to any one of claims 1 to 6, characterized in that the antioxidant agent is chosen from, pentaerythritol tetrakis (3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate), 2 ', 3- bis [3- [3,5-di-tert-butyl-4-hydroxyphenyl] propioyl] propionohydrazide, dioctadecyl 3,3'-thiodipropionate or a mixture thereof. [Claim 8] A polymeric matrix according to any one of claims 1 to 7 which contains a crosslinking promoting agent, such as 1, 3,5-triallylisocyanurate or trimethylolpropane trimethacrylate. [Claim 9] Polymeric matrix according to any one of claims 1 to 8, characterized in that it is free of plasticizer. [Claim 10] Use of the polymer matrix as defined in any one of claims 1 to 9, for the manufacture of insulators for electrically conductive wires. [Claim 11] Cable comprising at least one electrically conductive wire covered with a protective sheath based on the polymer matrix defined in any one of claims 1 to 10. [Claim 12] Use of a cable as defined in claim 10 or 11, for automotive wiring. [Claim 13] A method of preparing a cable according to claim 11 comprising: - the preparation of a polymeric matrix as defined in any one of claims 1 to 9 -extrusion of the matrix around an electrical conductor -and optionally the crosslinking of the polymeric matrix.