FORMULATION OF MATERIAL FOR INSULATING WIRE AND PRODUCT PRODUCED THEREFROM

Abstract

This invention falls within the scope of insulation materials, more specifically compounds aimed at insulating wires used in cars. It consists of a formulation comprising 10%-50% by mass of a polyethylene or polyethylene copolymers-based resin, 5%-20% by mass of a Thermoplastic Elastomer-based resin and 3%-6% by mass of a primary antioxidant with phenolic and metal deactivation properties. This formulation allows a compound to be obtained with high thermal, chemical and mechanical resistance. According to an improved configuration, it further comprises 10%-55% by mass of a mineral filler with flame retardant properties, 1%-3% by mass of a thioester-based antioxidant, 1%-3% by mass of a phosphite-based antioxidant and 0.5%-2% by mass of a phosphate-based antioxidant. Additionally, a product which is obtained by mixing the said formulation and subsequent crosslinking is also the object of this invention.

Claims

1. A formulation for obtaining wire insulation material, characterized in that it comprises: a. 10% to 50% by mass of a polyethylene and/or polyethylene copolymers-based resin; b. 5% to 20% by mass of a Thermoplastic Elastomer-based (TPE) resin; c. 3% to 6% by mass of a primary antioxidant with phenolic and metal deactivation properties.

2. A formulation according to claim 1, characterized in that it further comprises 0.1% to 4% by mass of Calcium Oxide and 0.1% to 5% by mass of Zinc Sulphate.

3. A formulation according to claim 1, characterized in that it additionally comprises: 10% to 55% by mass of a mineral filler with flame retardant properties; 1% to 3% by mass of a thioester-based antioxidant; 1% to 3% by mass of a phosphite-based antioxidant; 0.5% to 2% by mass of a phosphate-based antioxidant.

4. A formulation according claim 1, characterized in that it further comprises 1% to 2% by mass of an organosilane.

5. A formulation according to claim 1, characterized in that the organosilane is from the same family of vinyltrimethoxysilane and vinyltriethoxysilane.

6. A formulation according to claim 1, characterized in that the mineral filler has flame retardant properties and consists of one or more combined inorganic components.

7. A formulation according to claim 1, characterized in that the mineral filler with flame retardant properties is Magnesium Hydroxide.

8. A formulation according to claim 6, characterized in that the mineral filler with flame retardant properties is Aluminium Hydroxide.

9. A formulation according to claim 1, characterized in that the mineral filler is present in 45% to 55% by mass.

10. A formulation according to claim 1, characterized in that the polyethylene or polyethylene copolymers-based resin has a density of from 0.92 to 0.95 g/cm.sup.3.

11. A formulation according to claim 1, characterized in that the TPE comprises styrene.

12. A formulation according to claim 1, characterized in that the primary antioxidant is selected from the following compounds: pentaerythrityl-tetrakis [3 -(3, 5-di-tert-butyl-4-hydroxyphenyl)-propionate], 2,2-thiodiethylbis-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionate], octadecyl-3 -(3, 5-di-tert-butyl-4-hydroxyphenyl)propionate, 4,4-thiobis(6-tert-butyl-m-cresol), triethylene glycol-bis-3 (3 -tert-butyl-4-hydroxy-5-methyl phenyl)propionate, 4,4-thiobis[2-(1,1-dimethylethyl)-5-methylphenol, tetrakis[methylene(3,5-di-tert-butyl-4-hydroxy)cinnamate]methane or 2,2-Oxamido bis-[ethyl-3-(3,5-di-t-butyl-4-hydroxyphenyl) propionate.

13. A formulation according to claim 1, characterized in that the thioester-based antioxidant is dioctadecyl 3,3-thiodipropionate.

14. A formulation according to claim 1, characterized in that the phosphite-based antioxidant is one of the following compounds: tris(2,4-di-tert-butylphenyl)phosphite, Bis-(2,4-di-t-butylphenol) Pentaerythritol Diphosphite.

15. A formulation according to claim 1, characterized in that the phosphate-based antioxidant is 2,2,4-trimethyl-1,2-dihydroquinoline.

16. A product for obtaining wire insulation material, characterized in that the said material is obtained by: a. mixing the components of the formulation according to any of the previous claims; b. crosslinking by means of a crosslinking agent or by electron beam processing.

17. A product according to claim 1, characterized in that the crosslinking agent is organic peroxide in 0.1% to 2% by mass relative to the mass of the said formulation.

18. A product according to claim 1, characterized in that the crosslinking agent is selected from the group of t-butyl cumyl peroxide, benzoyl peroxide, cumene hydroperoxide, dicumyl peroxide, methyl ethyl ketone peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, di-tert-butyl peroxide, t-butyl peroxybenzoate.

19. A product according to claim 16, characterized in that, between the steps a) and b), the formulation is extruded and moulded, thus resulting in one or more moulded plates.

Description

EMBODIMENTS OF THE INVENTION

[0032] The following table shows 9 specific formulations according to this invention, all of them crosslinked with dicumyl peroxide, resulting in 9 products being obtained by mixing the components of the formulation and subsequent extrusion, after which the moulded plates were produced, the latter having been crosslinked by means of steam vulcanization or electron beam processing.

TABLE-US-00001 Components % by mass Formula (F) 1 F2 F3 F4 F5 F6 F7 F8 Polyethylene 0 0 25 24 29 14 19 20 Polyethylene Copolymer 29 32 5 5 5 5 5 9 TPE-S 5 5 5 5 5 10 10 5 Magnesium Hydroxide 50 50 50 50 50 50 50 50 Primary Antioxidant 6 6 4 4 2 6 6 6 Thioester Antioxidant 2 2 4 3 1 2 2 2 Phosphite Antioxidant 1 1 1 2 1 1 1 1 Phosphate Antioxidant 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Organosilane 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 Peroxide 1 1 1 1 1 1 1 0.2 ZnS 3 0 3 3 3 3 3 3 CaO 1 1 0 1 1 1 1 1

[0033] The formulae were produced and the crosslinked plates were tested according to the Standard ISO6722, with the following results being obtained:

TABLE-US-00002 Trials F1 F2 F3 F4 F5 F6 F7 F8 Density g/cm3 1.36 1.37 1.36 1.37 1.34 1.35 1.36 1.37 Breaking Load MPa 18 18.3 23.3 24.5 26.4 18.2 20.3 22.1 Elongation % 250 2350 205 198 190 300 270 210 Flame retardancy Pass Pass Pass Pass Pass Pass Pass Pass Winding to 40 C. for 4 h Pass Pass Pass Pass Fail Pass Pass Pass OIT 240 C. min 170 128 120 100 77 198 181 175 Aging 175 C. 240 h Pass Fail Pass Pass Fail Pass Pass Pass Aging 150 C. 3000 h Pass Fail Fail Fail Fail Pass Pass Pass Aging 175 C. 360 h Pass Fail Fail Fail Fail Pass Pass Pass Rheometry 30 min 150 C. 10 RPM Tr (min) 15:19 15:36 11:54 17:04 13:13 12:11 14:52 18:06 Tv (min) 02:16 02:07 02:43 03:33 02:45 04:47 01:23 04:33 Tc (min) 14:27 14:28 10:20 15:28 12:09 09:29 14:16 16:28 Maximum Torque % 26.5 27.9 55 30 39.1 28.1 29.9 30.3

[0034] The criterion used for the assessment of the aging trials was a minimum elongation of 50%, in order to ensure that the winding test referred to in the standard IS06722 is complied with. The Oxidative Induction Time (OIT) was used as a measure of the thermal resistance of the material when subjected to an oxygen atmosphere at a temperature of 240 C. All these tests were carried out while the material was in contact with a copper base, in order to assess the compound's resistance to oxidation under the action of copper. This OIT test makes it possible to determine if the formulation will have enough resistance to endure the test of the 3000 hours at 150 C. and it serves as an accelerated trial to the same, thus helping with obtaining a result within a short period of time.

[0035] Based upon these results, one verifies that, with this composition, the OIT values obtained are of around 190 min, which means a significant improvement in terms of thermal resistance comparatively to the values of the state of the art, which are typically lower than 150 min.

[0036] As demonstrated by the different formulations above described, this improvement arises from the presence of the TPE, the primary antioxidant and the Zinc Sulphate. In effect, it is an optimal formulation considering the different combinations disclosed by this invention.

[0037] A Brabender Rheometer with Roller blades was used to test the processability (maximum torque), and the reaction speed (Tr) and the cure rate (Tc) here illustrate the fact that the presence of Calcium Oxide allows for higher Tr and Tc when compared to a formulation without this additive, thus indicating a faster reaction, which can lead to the formation of gels and, consequently, problems in the crosslinking of the product. The maximum torque, which in this case is also higher, indicates a lower processability of this material. These results were confirmed in the tests performed in an extrusion line. Therefore, the said results lead us to conclude that the developed compounds represent an improvement and an advantage as regards the safety of the process, as well as its yield, thus allowing for an optimization of the resources when compared to the known state of the art.

[0038] As will appear evident to a person skilled in the art, this invention shall not be limited to the embodiments described in this document, with several modifications being feasible provided that they are kept within the scope of this invention.