HIGHLY INSULATED RUBBER COMPOSITION, PROCESSING METHOD THEREFOR, AND USES THEREOF

Abstract

Provided are a highly insulated rubber composition, a processing method therefor, and an application thereof. The rubber composition comprises a rubber matrix and compounding components. In parts by weight, every 100 parts of said rubber matrix comprise: 50-95 parts of a chlorinated (and/or chlorosulfonated) polyethylene rubber, 5-50 parts of a highly branched polyethylene, and 0-30 parts of an ethylene propylene rubber; and, the branching degree of the highly branched polyethylene is not lower than 50 branches/1000 carbon atoms. The compounding components contain a vulcanization system. The rubber composition improves the electrical insulation performance of the chlorinated (and/or chlorosulfonated) polyethylene rubber, so that the rubber composition is more suitable for the applications with high requirements for electrical insulation.

Claims

1. A rubber composition, comprising a rubber matrix and compounding components, wherein, in parts by weight, every 100 parts of said rubber matrix comprise: 50-95 parts of a chlorinated (and/or chlorosulfonated) polyethylene rubber, 5-50 parts of a highly branched polyethylene, and 0-30 parts of an ethylene propylene rubber; and said compounding components comprise a vulcanization system.

2. The rubber composition according to claim 1, wherein, said highly branched polyethylene is an ethylene homopolymer with a branching degree of not lower than 50 branches/1000 carbon atoms.

3. The rubber composition according to claim 2, wherein, the branching degree of said highly branched polyethylene is 60-130 branches/1000 carbon atoms.

4. The rubber composition according to claim 2, wherein, the branching degree of said highly branched polyethylene is 70-120 branches/1000 carbon atoms.

5. The rubber composition according to claim 1, wherein, said ethylene propylene rubber is an ethylene propylene diene monomer rubber.

6. The rubber composition according to claim 1, wherein, in parts by weight, every 100 parts of said rubber matrix further comprise 1-20 parts of a compatibilizer, and said compatibilizer is a reaction product of an ethylene propylene rubber or a highly branched polyethylene through polarization modification.

7. The rubber composition according to claim 6, wherein, said compatibilizer is low chlorinated polyethylene (LCPE) having a chlorine content of 2%-20%, wherein, a polyethylene raw material used for preparing said low chlorinated polyethylene (LCPE) is selected from at least one of a high density polyethylene, a low density polyethylene and a highly branched polyethylene.

8. The rubber composition according to claim 1, wherein, said vulcanization system is selected from at least one of a peroxide vulcanization system, a thiourea vulcanization system, a thiadiazole vulcanization system, a metal-oxide vulcanization system, and a radiation vulcanization sensitizing system.

9. The rubber composition according to claim 8, wherein, said vulcanization system is a peroxide vulcanization system, based on 100 parts by weight of said rubber matrix, the usage amount of the peroxide is 1-10 parts by weight, and the peroxide crosslinking agent is at least one of di-tert-butyl peroxide, dicumyl peroxide, tert-butyl cumyl peroxide, 1,1-di(tert-butylperoxy)-3,3,5-trimethylcyclohexane, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, 2,5-dimethyl-2,5-di(tert-butylperoxy)-3-hexyne, bis(tert-butylperoxyisopropyl)benzene, 2,5-dimethyl-2,5-bis(benzoyl peroxide)hexane, tert-butyl peroxybenzoate, and tert-butyl-peroxy-2-ethylhexyl carbonate.

10. The rubber composition according to claim 9, wherein, said peroxide vulcanization system comprises 0.2-20 parts by weight of an auxiliary crosslinking agent, and said auxiliary crosslinking agent comprises at least one of triallyl cyanurate, triallyl isocyanurate, ethylene glycol dimethacrylate, triethylene glycol dimethacrylate, triallyl trimellitate, trimethylolpropane trimethacrylate, N,N′-m-phenylene bismaleimide, N,N′-bis(furfurylidene) acetone, 1,2-polybutadiene, an unsaturated carboxylic acid metal salt, and sulfur.

11. The rubber composition according to claim 1, wherein, based on 100 parts by weight of said rubber matrix, said compounding components comprise 10-200 parts of a reinforcing filler, 0-80 parts of a plasticizer, 3-30 parts of a metal oxide, 0-3 parts of stearic acid, 0-15 parts of a surface modifier, 1-15 parts of a stabilizer, 0-150 parts of a flame-retardant agent, and 0-20 parts of a foaming agent.

12. A wire or cable, having an insulating layer, wherein, the rubber used for said insulating layer comprising said rubber composition according to claim 1.

13. A wire or cable, having a sheathing layer, wherein, the rubber used for said sheathing layer comprising said rubber composition according to claim 1.

Description

DETAILED DESCRIPTION

[0043] The following examples are given to further illustrate the present invention, and not intended to limit the scope of the present invention. Some non-essential improvements and modifications made by the skilled person in the art based on the disclosure herein are still within the scope of the present invention.

[0044] The branched polyethylene raw material used in the examples are characterized by preferably having a branching degree of 50-130 branches/1000 carbon atoms, a weight average molecular weight of 6.6×10.sup.4-53.4×10.sup.4 g/mol, and a Mooney viscosity ML(1+4) at 125° C. of 6-105. The branching degree is measured by 1H NMR, and the molar percentages of various branches are measured by 13C NMR.

[0045] The branched polyethylene raw material is further selected from the following table:

TABLE-US-00001 Hexyl and Weight Molecular Mooney longer average weight viscosity Branchedpoly- Branching- Methyl- Ethyl- Propyl- Butyl- Amyl- branches molecular Distri- ML(1 + ethylene # degree content/% content/% content/% content/% content/% content/% weight/×10,000 bution 4)125° C. PER-1 130 46.8 18.3 8.3 6.7 5.2 14.7 6.6 2.2 6 PER-2 120 49.2 17.9 8.2 6.1 5.1 13.5 8.2 2.1 12 PER-3 112 52.4 16.2 7.6 5.6 4.9 13.3 22.5 1.9 32 PER-4 105 54.0 13.7 6.4 5.3 5.1 15.5 26.8 2.1 42 PER-5 102 56.2 12.9 6.2 5.2 4.9 14.6 27.9 2.1 52 PER-6 99 59.6 11.6 5.8 4.9 5.1 13.0 28.3 1.8 63 PER-7 97 60.5 10.8 5.7 4.7 4.9 13.3 34.8 2.0 65 PER-8 90 62.1 9.4 5.4 4.6 4.5 14.0 32.1 2.1 77 PER-9 82 64.2 8.7 5.3 4.2 3.9 13.7 35.6 1.7 80 PER-10 72 67.1 6.2 3.7 4.1 3.3 15.6 15.8 1.9 20 PER-11 70 66.5 7.2 4.6 3.2 3.2 15.3 43.6 2.1 93 PER-12 60 68.1 7.1 4.2 2.7 2.8 15.1 51.8 2.2 102 PER-13 50 69.2 7.1 3.9 2.5 2.6 14.7 53.4 2.3 105

[0046] The compatibilizer used in the examples of the present invention is chlorinated polyethylene with a low chlorine content, which is prepared by introducing chlorine gas into a hexane or carbon tetrachloride solution containing a branched polyethylene and a radical initiator (e.g., azodiisobutyronitrile), and controlling different reaction temperatures and times, to obtain different LCPEs.

[0047] Halogen-containing branched polyethylenes used in the examples of the present invention are selected from the following table:

TABLE-US-00002 Branched polyethylene Mass percentage of LCPE # raw material # chlorine element/% LCPE-1 PER-5 5.3 LCPE-2 PER-7 12.9

[0048] The chlorinated polyethylene rubber used in the examples of the present invention has a chlorine content of 35%, and a Mooney viscosity ML(1+4) at 125° C. of 76; the chlorosulfonated polyethylene rubber used in the examples of the present invention has a chlorine content of 35%, a sulfur content of 1%, and a Mooney viscosity ML(1+4) at 125° C. of 43; and the EPDM used in the examples of the present invention has an ENB content of 4.5%, a Mooney viscosity ML(1+4) at 125° C. of 48, and an ethylene content of 55%.

[0049] Test Methods of Rubber Performances:

[0050] 1. Tensile strength and elongation at break performance test: the test is performed by using an electronic tensile tester in accordance with the national standard GB/T528-2009, at a tensile speed of 500 mm/min and a test temperature of 23±2° C., with a type 2 dumbbell sample;

[0051] 2. Mooney viscosity test: the test is carried out in accordance with the national standard GB/T1232.1-2000, with a Mooney viscosity meter at a test temperature set according to actual conditions by preheating for 1 minute, and the test is continued for 4 minutes;

[0052] 3. Volume resistivity test: the test is performed by using a megger in accordance with the national standard GB/T1692-2008; and

[0053] 4. Oxygen index test: the test is performed in accordance with the national standard GB/T2046.2-2009.

Examples 1-7 and Comparative Example 1

[0054] The rubber compositions of Examples 1-7 and Comparative example 1 have the compositions as shown in Table 1: (the parts by weight of the components based on 100 parts by weight of the rubber matrix are listed in the table)

TABLE-US-00003 TABLE 1 Comparative Example Example Example Example Example Example Example Component Example 1 1 2 3 4 5 6 7 Amount of CM 100 90 80 70 70 70 50 Amount of CSM 60 PER # PER-6 PER-9 PER-5 PER-5 PER-5 PER-3 PER-7 Amount of PER 10 20 30 15 25 32 40 Amount of EPDM 15 LCPE # LCPE-1 LCPE-1 LCPE-2 Amount of LCPE 5 8 10 MgO 5 5 5 5 5 5 5 5 White carbon black 30 30 30 30 30 30 30 30 Talcum powder 20 20 20 20 20 20 20 20 Dioctyl adipate 15 15 15 15 15 15 15 15 Paraffin 1 1 1 1 1 1 1 1 Chlorinated paraffin 4 4 4 4 4 4 4 4 Calcium stearate 1 1 1 1 1 1 1 1 Anti-aging 1 1 1 1 1 1 1 1 agent RD Silane coupling 3 3 3 3 3 3 3 3 agent A-172 Antimony oxide 10 10 10 10 10 10 10 15 Zinc borate 5 5 5 5 5 5 5 10 Aluminium 15 15 15 15 15 15 15 20 hydroxide DCP 4 4 4 4 4 4 4 4 TAIC 2 2 2 2 2 2 2 2

[0055] The mixing processes of Examples 1-7 and Comparative example 1 were as follows:

[0056] The internal mixer was set to an initial temperature of 90° C. and a rotor speed of 40 rpm. All of the dry agents and liquid agents except for DCP and TAIC were added successively, and mixed for 3 min, and then the rubber matrix was added. After mixing power was stable, DCP and TAIC were added, and mixed for 1 min, and then a rubber mix was discharged. The rubber mix was then plasticated on an open mill to a sheet, unloaded and cooled down, and the sheet was allowed to stand for 24 h. After that, the sheet was remixed and discharged.

[0057] All tests were prepared and tested according to standards. The vulcanizing method was carried out by using mold pressing vulcanization, at a vulcanizing temperature of 170° C. and a pressure of 16 MPa for Tc 90+1 min, and the tests were performed after standing for 16 h. The performance data of the test samples were as shown in Table 2:

TABLE-US-00004 TABLE 2 Comparative Example Example Example Example Example Example Example Performance example 1 1 2 3 4 5 6 7 Tensile strength/MPa 16.3 16.8 17.3 17.5 17.1 17.8 18.2 19.5 Elongation at break 618 591 551 575 534 582 571 558 Oxygen index/% 33.8 33.2 32.1 31.6 31.5 31.7 30.6 33.4 Volume 1.9 2.1 2.8 3.7 3.6 3.6 4.2 5.7 resistivity/ 10.sup.13 Ω .Math. cm

[0058] It can be seen from the comparison between Examples 1-3 and Comparative example 1 that, with the increase in the content of the highly branched polyethylene, the volume resistivity of the rubber composition increases significantly, and electrical insulation performance is improved. It can be seen from the comparison between Example 3 and Example 4 that replacing the EPDM with the highly branched polyethylene can not only increase the volume resistivity, but also improve the overall mechanical strength. It can be seen form the comparison between Example 3 and Example 5 that by adding the compatilizer, the blending compatibility and mechanical strength of the rubber composition of the present invention can be effectively improved.

[0059] The rubber compositions of the above examples can be used as wire and cable sheathing materials having specific requirements on flame-retardant and insulating properties.

Examples 8-4 and Comparative Example 2

[0060] The rubber compositions of Examples 8-14 and Comparative example 2 have the compositions as shown in Table 3: (the parts by weight of the components based on 100 parts by weight of rubber matrix are listed in the table)

TABLE-US-00005 TABLE 3 Comparative Example Example Example Example Example Example Example Example Example 2 8 9 10 11 12 13 14 Amount of CM 100 95 85 70 70 60 50 50 PER # PER-10 PER-8 PER-11/PER-2  PER-7 PER-6 PER-9/PER-3 PER-5 Amount of PER 5 15 20/10 30 30 20/15 50 LCPE # LCPE-1 LCPE-2 Amount of LCPE 10 15 MgO 10 10 10 10 10 10 10 10 Aluminium 30 30 30 30 30 30 30 30 hydroxide Talcum powder 20 20 20 20 20 20 20 20 Calcined clay 40 40 40 40 40 40 40 40 Dioctyl sebacate 30 30 30 30 30 30 30 30 Zinc stearate 1 1 1 1 1 1 1 1 Calcium stearate 1 1 1 1 1 1 1 1 Antioxidant RD 1 1 1 1 1 1 1 1 BIBP 4 4 4 4 4 4 4 4 TAIC 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5

[0061] The mixing processes of Examples 8-14 and Comparative example 2 were as follows:

[0062] The internal mixer was set to an initial temperature of 90° C. and a rotor speed of 40 rpm. All of the dry agents and liquid agents except for BIBP and TAIC were added successively, and mixed for 3 min, and then the rubber matrix was added. After mixing power was stable, BIBP and TAIC were added, and mixed for 1 min, and then the rubber mix was discharged. The rubber mix was then plasticated on an open mill to a sheet, unloaded and cooled down, and the sheet was allowed to stand for 24 h. After that, the sheet was remixed and discharged.

[0063] All tests were prepared and tested according to standards. The vulcanizing method was carried out by using mold pressing vulcanization, at a vulcanizing temperature of 165° C. and a pressure of 16 MPa for Tc 90+1 min, and the tests were performed after standing for 16 h. The performance data of the test samples were as shown in Table 4:

TABLE-US-00006 TABLE 4 Comparative Example Example Example Example Example Example Example Performance Example 2 8 9 10 11 12 13 14 Tensile strength/MPa 12.8 13.1 13.5 13.6 15.8 15.3 16.1 15.3 Elongation at break 532 546 528 517 525 561 557 498 Volume 3.7 3.8 4.6 6.2 6.1 7.3 8.2 8.8 resistivity/ 10.sup.14 Ω .Math. cm

[0064] It can be seen from the comparison that, with the increase in the content of the highly branched polyethylene, the volume resistivity of the rubber composition increases accordingly, and the electrical insulation performance is improved effectively. Therefore, the rubber composition is useful as an insulating layer material of the medium- and low-voltage wires and cables.

[0065] Although preferred embodiments of the present invention have been described herein, these embodiments are provided merely by way of examples. It is to be understood that variations of the embodiments of the present invention described herein can also be used in the practice of the present invention. It will be appreciated by those skilled in the art that various modifications, changes and substitutions can be made without departing from the scope of the present invention. It is to be understood that the scope of the present invention is defined by the appended claims, and the methods, structures, and equivalents thereof within the scope of the claims are also contemplated in the scope of the claims.