AU689525B2

AU689525B2 - Elastomeric compositions

Info

Publication number: AU689525B2
Application number: AU12690/95A
Authority: AU
Inventors: Sayid Bassiray; Arthur Charles Day; Alfred Johannes Eiden; Victor John Russ
Original assignee: Pacific Dunlop Ltd
Current assignee: Olex Australia Pty Ltd
Priority date: 1993-12-15
Filing date: 1994-12-15
Publication date: 1998-04-02
Anticipated expiration: 2014-12-15
Also published as: AU1269095A

Description

WO 95/16728 PCT/AU94/00773 1

TITLE

Elastomeric Compositions FIELD AND BACKGROUND OF THE INVENTION This invention relates to elastomeric compositions particularly those compositions for use in electrical cables. Certain electrical cables require insulation covering and sheath with elastomeric compositions that are halogen free, flame retardant and resistant to fluids. Where cables are used in marine applications there are a number of standards that define the operating qualities and characteristics of both the elastomeric compositions in the cables. Such standards include British Naval Engineering Standards NES 518, NES 525 and NES 526. The Australian Department of Defence (NAVY) has a comparable standard known as A014000. The elastomeric composition described hereunder has been designed to preferably satisfy all of the standards referred to above.

When cables are used in a marine environment, there is an inherent necessity to withstand hostile conditions and rough usage. The cables can be exposed to salt water and a variety of hydrocarbon fluids such as hydraulic fluid, diesel, fuel and lubricating oils. It is important that cables can operate for long periods and are 2

C

C C designed to withstand damage from the hostile environment.

One of the most feared occurrences at sea is fire. The confined configuration of marine vessels made it essential that electrical fires or action damage fires are not spread by flaming cables. It is also critical that if the cables do catch fire that they do not produce hazardous hydrochloric fumes or other corrosive volatiles. A further demand for cables for use in marine applications is the ability to operate satisfactorily for long periods over a wide temperature range and have a good capacity to withstand abrasive forces.

The present imnvntion relates to materials particularly for use in the sheathing and insulation covering where applicable of cables of this kind.

15 SUMMARY OF THE INVENTION According to one aspect of the present invention there is provided a halogen free elastomeric composition comprising at least one ethylene acrylate copolymer and fully hydrogenated butadiene/acrylonitrile copolymer, the elastomeric composition being cross-linked to meet the mechanical property characteristics required by Australian Department of Defence (Navy) Standards A014000.

Preferably, the acrylate elastomer is ethylenemethyl acrylate (EMA). However, it is understood that the acrylate elastomer may also be ethylene-ethyl acrylate (EEA) or ethylene-butyl acrylate (EBA).

According to a still further aspect of the present invention, there is provided a halogen free elastomeric composition comprising (in parts by weight): a) 50 to 80 parts of ethylene-methyl acrylate (EMA) copolymer with acrylate content of greater than b) 20 to 50 parts of a fully hydrogenated butadiene/acrylonitrile copolymer with acrylate content greater than 30%, the total polymer content of and (b) making 100 parts; c) 2 to 5 parts of processing aid; d) 100 to 170 parts of aluminium hydroxide or/and L H:\ann\Keep\Temp\12690-95-2ND.doc 5/02/98 9 I

ICO

12 N4

I

3 with other endothermic filler of BET surface area of between 5 and 20 m 2 /g; e) 1 to 4 parts of antioxidant; f) 1 to 10 parts of colorant; whereby the elastomeric composition is cross-linked to meet the property characteristics required by Australian Standard A014000.

The invention also relates to an electrical cable sheathed and insulated by the elastomeric composition described above.

DESCRIPTION OF PREFERRED EMBODIMENTS The development of elastomeric composition for use in cables for marine applications requires careful consideration of applicable standards that define the operating qualities. One such standard is Australian Standard AO 14000.

A particularly difficult requirement of this standard is the resistance to a range of fluids such as aviation fuels, hydraulic fluids (both petroleum and 20 silicone based), lubricating oils (both detergent mineral based and synthetic ester based), mineral oil as represented by ASTM reference oil No. 2 and deionised water, and deionised water with 3.5% sodium chloride.

Other requirements are that the compound is halogen free, while achieving a flame retardance of limiting oxygen index 32 minimum, and in combination with the other cable components, produces a cable of specified resistance to flame propagation, be low in smoke and low in toxicity under combustion conditions. Mechanical properties of the 30 compound must be maintained to tensile 6.0 MPa minimum, elongation 125% minimum and tear 5N/mm minimum. In addition, the compound in combination with the other cable components must provide a low temperature flexibility of up to -200C.

In developing a suitable elastomeric composition, a variety of compounds were produced essentially comprising a mixture of Ethylene Acrylic (EA) Rubber and hydrogenated H:\ann\keep\temp\1269-95-1ST.1 27/05/97 WO 95/16728 PCT/AU94/00773 4 Nitrile Butadiene Rubber (HNBR) in a range of proportions.

Although the invention contemplates the use of a variety of ethylene acrylic (EA) rubbers including ethylene-methyl acrylate (EMA), ethylene-ethyl acrylate (EEA) and ethylenebutyl acrylate (EBA) the majority of four experimentation and testing was conducted on a composition including EMA.

Compound 1 was 100% EMA, compound 2 had an EMA/HNBR ratio of 85/15, in compound 3 the ratio was 50/50, in compound 4 the ratio was 25/75 and compound 5 was 100% HNBR. All the compounds were tested for tensile strength and elongation properties. Compounds 1, 2 and 3 were tested for tear resistance and compounds 2 and 3 were also tested to fluid immersion with lubricating oil 0X38 (Aeroshell 750) for 28 days at 50 0 C as specified in paragraph 6.2 of the specification of Australian Standard A014000. Compound 3 was also tested against the other fluid immersion types referred to in paragraph 6.2 of the Australian Standard.

The EMA used in these tests was a Du Pont product sold under the trademark VAMAC N123. The material composition of this product is a copolymer of ethylene-methyl acrylate and a third monomer containing carboxylic curing sites. It also contains 23 parts of compounding ingredients for each 100 parts of ethylene-acrylic elastomer. The HNBR used in these tests was a Bayer product sold under the trademark THERBAN and essentially comprise hydrogenated butadiene/acrylonitrile rubber. The acrylic content of the EMA was in the order of 40% for VAMAC N123. The acrylonitrile content of HNBR was 38% (Therban 1907).

Further details of the processing aids, fillers, antioxidants, colourants, curing agents and other additions WO 95/16728 WO 9516728PCT/AU94/00773 are listed from the following table: Process Aids Name parts per hundred ARMEEN 18D 0.5 Stearic Acid 2.0 Powder 2.0 Composition N-octadecyl amine N-octadecanoic acid Metal oleates, stearates, hydrocarbons and monohydroxy compounds Fillers Name HYDRAL 710 MISTRON Vapour Talc APYRAL B120 PERKASIL KS 404GR Composition Aluminium Hydroxide Magnesium Silicate Aluminium Hydroxide Silica Specific Surface Area (BET) 6-8 10-12 Antioxidants Name

SANTOWHITE

Composition 4, 4' butylidene bis 6-t-butyl-mcres 01 Colourants UV stabilizer composition SAF Carbon Black N110 (ASTM) Type Carbon Black Super Abrasion Furnace Black Curing Agents Name HVA2 (accelerator) PERKAflOX 14-40MB (crosslinking agent) composition N, N'-m-phenylenedimaleimide Bis (Tert-butylperoxy-Isopropyl) benzene Other Additive Deodourant Vanillin WO 95/16728 PCT/AU94/00773 6- A specific example of a composition made in accordance with the provisions of this invention is listed hereunder: Example phr VAMAC N123 62 THERBAN 1907 MISTRON Vapour Talc HYDRAL 710 150 SANTOWHITE Powder 2 ARMEEN 18D Vanillin 0.2 Stearic Acid 2 HVA2 2 PERKADOX 14-40MB SAF Black The compound was used in the laboratory using two roll mills. It was then pressed into sheets at 160 0 C for sixty minutes, and the sheets were watercooled to room temperature. Samples from the prepared sheets were then tested for a series of unaged and aged physical properties.

The results of these tests are shown in Table 1.

The samples prepared from the moulded sheets were then left in a constant temperature room to stabilise for 24 hours before testing. The stabilised moulded sheets were then cut into dumbbells and evaluated to determine the unaged mechanical properties including tensile strength, elongation at break and tear resistance followed by the determination of mechanical properties of heat aged samples and a wide range of fluid immersion properties. These results are shown in Table 2.

Tests were conducted on an elastomeric composition that was essentially VAMAC with evaluation of the HFS-90-R and HFS-10-R cable ratings to meet the fluid resistance tests as specified in Australian Standard

I

WO 95/16728 PCT/AU94/00773 7 A014000. It was discovered that the compound that consisted merely of VAMAC when immersed in Fluid Type C2 (OX 38, Aeroshell 750) for 28 days at 500 failed to meet the specified criteria.

A compound that incorporated 50% HNBR and VAMAC in accordance with the example listed above was then evaluated to determine its tear, heat ageing and fluid immersion properties.

The composition was therm-chemically cross linked but it is understood that other curing techniques are envisaged such as electro-beam cross linking with appropriate compound modifications.

I

TABLE 1 t I Test Unaged Mechanical Properties Tensile Strength (mPA) Elongation Tear Resistance (Nmm-') Mechanical properties after ageing at 1300C for 20 days Tensile Strength (mPA) Elongation Limiting Oxygen Index L.O.I.

Weathering Tensile Strength Retained Elongation Retained Surface Examination Under Magnification Hardness IRHD Acid and Corrosive Gas Emission 1. pH minimum 2. Conductivity pS.cm Result 8.3 265 5.3 12.8 150 40 115 97 No Cracks 82 Specified A014000 6.0 minimum 150 minimum 5.0 minimum 6.0 minimum 100 minimum 32 75 minimum 75 minimum No Cracks 55 minimum, 85 maximum 3.5 minimum 100 maximum .1 PT-D/C 648 TABLE 2 fFluid Immersion Fluid Type Propulsion Fuels Al F76 A2 F44 Hydraulic Fluids Bl 0x30 B2 HS200 X Lubricating Oils Cl OMDll13 C2 0X38 (Aeroshell) Mineral Oil Dl ASTM Oil. No. 2 Water El Deionised Water E2 Deionised Water Test Conditions 24 hours at 100'C 24 hours at. 50*C 28 days at 5000 28 days at 50'C 28 days at 50'0 28 days at 5 0

'C

18 hours at 120*C 28 days at 50'C 28 days at 5000 Retained M%) La 101% 98% 122% 84% 124% 105' 127% 100% 111% 83% 89% 94% 119% Specified A0l14000 Retained 0/) 60 min.

min.

60 min.

min.

60 min.

80 min.

75% 79% 60 min.

60 min.

60 min, 80 min.

80 min.

92% 87% 81% .1 I WO 95/16728 PCT/AU94/00773 10 It is considered that this particular compound passes the unaged and aged mechanical criteria tests and also the fluid immersion criteria tests for cable ratings and HFS-110-R. HFS-90-R defines a sheath characteristic of a halogen free elastomeric compound based on cross-linked ethylene acrylate copolymer, suitable for up to and including a maximum of 90 0 C continuous operating temperature. HFS-110-R relates to a higher temperature veasiSion of HFS-90-R, suitable for up to and including a maximum of 110°C continuous operating temperature.

I WO 95/16728 PCT/AU94/00773 11 A copy of pages 19, 28, 29 and 30 taken from Australian Departsment of Defence (Navy) Standard A014000 -i ,Gvt WO 95/16728 PCT/AU94100773 12 SPECIFICATION A014000 ISSUE 1 NOVEMBER 1993 6. TESTS 6.1 GENERAL Cables shall be capable of complying with the tests specified in Table 7. All tests shall be made as specified in Table 7 and Clause 9.

In some individual cases cables may be subject to additional tests not included in Table 7. Such additional tests, if any, are detailed in the individual specification sheets (see Appendix D).

Attention is drawn to Appendix A in respect to safety measures when performing some of the tests specified.

Except where otherwise specified, the tests listed in Table 7 need not be performed in the order numbered.

6.2 FLUID IMMERSION The test method, as is specified for Mineral Oil Immersion Test in AS1660, applies except that the following conditions and fluids shall be used: Type A (Propulsion fuels) Fuel oil, NATO F-76 to DEF (AUST) 5213, specimens immersed for 24h at 100 3 0

C.

(ii) Aviation turbine fuel, F-44 AVCAT/FSII to DEF(AUST)5207, specimens immersed for 24h at 50 cTTPc~r~rrc crr~n7r Tr)lifP 76\ WO 95/16728 PCT/AU94/00773 13 2 0

C.

Type B (Hydraulic fluids) Hydraulic fluids (Petroleum based), 0X30 to DEF STAN. 91-35/1, specimens immersed for 28 days at 50 2 0

C.

(ii) Hydraulic fluid (Silicone based), HS200X, specimens immersed for 28 days at 50 2 0

C.

Type C (Lubricating oils) Lubrication oil (Detergent mineral based), OMD 113 to DEF STAN 91-22/2, specimens immersed for 28 days at 2 0

C.

(ii) Lubrication oil (synthetic ester based), 0X38 to DERD 2487 (Issue 4), specimens immersed for 28 days at 2oC.

Type D (Mineral oil) Mineral oil as is specified in AS1660, with the specimens subjected to the following immersion time and temperature: HFS-90-R or HFS-110-R sheathed for 18h at 120 3 0

C.

(ii) HFS-90-TP sheathed for 4h at 70 2 0

C.

Type E (Water) Deionised water, specimens immersed for 28 days at 50 A 2oC.

(ii) Deionised water 3.5% by mass Na Cl, specimens immersed for 28 days at 2 0

C.

Any use of alternative fluids shall be subject to a written approval by the QA.

On completion of the test, the specimen shall meet the criteria specified in Table 9.

SUBSTITUTE SHEET (Rule 26) SPECIFICATION A014000 ISSUE 1 NOVEMBER 1993 Table 9 TESTS FOR MATERIAL CHARACTERISTICS OF SHEATH CRITERIA, CATEGORY AND REFERENCE (See NOTES 1,2 3) 2 3 4 5 6 1 Test Criteria Category Reference HFS-110-R HFS-90-TP of for test SHEATH SHEATH SHEATH test method A. Mechanical tests without Type AS 1660 ageing on conditioned specimens: 1. Tensile strength, 6.0 6.0 minimum (MPa) 2. Elongation at rupture, 150 150 100 minimum (percent) 3. Tear resistance, minimum 5 5 (N/mn) B. Mechanical tests after Type AS 1660 ageing in air oven (see NOTE 2) Duration (hrs) and 240 h at 480 h at 240 h at temperature of ageing 120 3 130 3 100 2 (deg.C) 1. Tensile strength, actual 6.0 6.0 minimum (MPa) 2. Elongation at rupture, 100 100 actual minimum (percent) i 2 3 4 56 Test criteria Category Reference HFS-110-R HFS-90-TP of for test SHEATH SHEATH SHEATH I test method C Fluid immersion: Type AS in (conditions per Clause 6.2) AS 1660 for 1. Tensile strength, minimum Mineral (percentage of values oil found in the unaged immersion specimens) test Fluid types: A, B, C, 60 60 D, 60 60

E,

s0 2. Elongation at rupture, minimum (percentage of values found in the enaged specimens) Fluid types: A, B, C, 60 60 D, 60 60 s 80 D. Loss of mass, maximum (see NOTE 2.0 Type AS 1660 2) (mean loss in mg/sq.cm of exposed surface of specimen) 2 3 456 Test criteria Category Reference HFS-110-R HFS-90-TP of for test SHEATH SHEATH SHEATHtetm ho E. Pressure test at high Type AS 1660 temperature: Test temperature (deg.C) -90 ±2 identification, maximum (percent) F. Heat shock -The sheath Type AS 1660 shall show no sign of cracking or flaking either when initially wound on the mandrel or after the test.

G. Limiting oxygen index, 32 30 34 Type AS 2122 minimum___ H. Temperature index, minimum 250 250 250 Type Clause (deg. C) J. Acid and corrosive gas Type AS 1660 emission: 1. PH, minimum 3.5 3.5 2. Conductivity, maximum [(micro S cm(to the 100 100 100 minus 2 3 456 Test criteria Category Reference HFS-110-R HFS-90-TP of for test SHEATH SHEATH SHEATH test method K. Duoetr adnss(RH)Type

ASTM

D2 240 L WeteigType

ASTM

D2565 Tensile strength minimum 75 75 75 and (percentago. of value found clause in unweathered specimen) 6.6 Elongation at rupture minimum (percentage of 75 75 value found in unweathered specimen) surface examination under x ma~gnification No cracks No cracks No cracks NOTES: 1. A hyphen in the Criteria column means that the test is not applicable for the given sheath.

2. For HFS-90-TP the test procedure Ain AS 1660 for Thermal Ageing and Loss of mass for PVC shall be followed.

3. The tests are to be performed on samples from flat moulded sheets 2mm t 0.2 mm thick prepared under Laboratory conditions.

Claims

1. A halogen free elastomeric composition comprising at least one ethylene acrylate copolymer and fully hydrogenated butadiene/acrylonitrile copolymer, the elastomeric composition being cross-linked to meet the mechanical property characteristics required by Australian Department of Defence (Navy) Standards A014000.

2. The composition according to claim 1 wherein the ethylene acrylate copolymer is chosen from the group comprising ethylene-methyl acrylate (EMA), ethylene-ethyl acrylate (EEA), ethylene-butyl acrylate (EBA), and mixtures thereof.

3. A halogen free elastomeric composition comprising 15 (in parts by weight): a) 50 to 80 parts of ethylene-methyl acrylate (EMA) copolymer with acrylate content of greater than b) 20 to 50 parts of a fully hydrogenated butadiene/acrylonitrile copolymer with acrylate content 20 greater than 30%, the total polymer content of and (b) making 100 parts; c) 2 to 5 parts of processing aid; d) 100 to 170 parts of aluminium hydroxide or/and with other endothermic filler of BET surface area of between 5 and 20 m 2 /g; e) 1 to 4 parts of antioxidant; f) 1 to 10 parts of colorant; whereby the elastomeric composition is cross-linked to meet the property characteristics required by Australian Standard A014000.

4. An electrical cable insulated and sheathed by the elastomeric composition according to any one of the preceding claims. A halogen free elastomeric composition substantially as described herein with reference to the Example. R 6. An electrical cable insulated and sheathed by the H:\ann\Keep\Temp\12690-95-2ND.dOc 5/02/98 19 elastomeric composition of claim Dated this 5th day of February 1998. PACIFIC DUNLOP LIMITED By Its Patent Attorneys GRIFFITH HACK Fellows Institute of Patent Attorneys of Australia H:\ann\Keep\Temp\12690-95-2Nfl.doc 5/02/98 INTERNATIONAL SEARCH REPORT International application No. PCT/AU 94/00773 A. CLASSIFICATION OF SUBJECT MATTER Int. Cl. 6 C08J 3/24; C08F 299/00; C08L 9/02, 33/08, 33/10; H01B 3/28, 3/44 According to International Patent Classification (IPC) or to both national classification and IPC B. FIELDS SEARCHED Minimum documentation searched (classification system followed by classification symbols) IPC C08J 3/24; C08F 299/00 Documentation searched other than minimum documentation to the extent that such documents are included in the fields searched AU IPC as above Electronic data base consulted during the international search (name of data base, and where practicable, search terms used) DERWENT C08J 3/24, C08f 299/00 Acry:(S)elastomer or Butadien: C. DOCUMENTS CONSIDERED TO BE RELEVANT Category* Citation of document, with indication, where appropriate, of the relevant passages Relevant to Claim No. US,A, 5051480 (CORAN) 24 September 1991 (24.09.91) X col. 1 lines 29-60 1 EP,A1, 531788 (BAYER) 17 March 1993 (17.03.93) X page 1 lines 11-14, 24-31, page 4 lines 25-28 1, 6 US,A, 4591615 (ALDRED et al) 27 May 1986 (27.05.86) A see whole document 1-7 X Further documents are listed See patent family annex. in the continuation of Box C. Special categories of cited documents later document published after the international filing date or priority date and not in conflict document definingthe general state of the art which is with the appliation ut cited to understand the not considered to be ofparticular relevance orinciple or theory underlying the invention earlier document but published on or after the iocument of partcular relevance; the claimed international filing date invention cannot be considered novel or cannot be document which may throw doubts on priority claim(s) considered to involve an inventive step when the or which is cited to establish the publication date of document is taken alone another citation or other special reason (as specified) document of particular relevance; the claimed document referring to an oral disclosure, use, invention cannot be considered to involve an exhibition or other means inventive step when the document is combined document published prior to the international filing date with one or more other such documents, such but later than the priority date claimed combination being obvious to a person skilled in the art document member of the same patent family Date of the actual completion of the international search Date of mailing of the international search report 13 March 1995 (13.03.95) (1 0c Cts5 (jb. O .1 Name and mailing address of the ISA/AU Authorized officer AUSTRALIAN INDUSTRIAL PROPERTY ORGANISATION /1 PO BOX 200 WODEN ACT 2606 AUSTRALIA GRAN McNEICE Facsimile No. 06 2853929 Telephone No. (06) 2832055 Form PCT/ISA/210 (continuation of first sheet (July 1992) cophin INTERNATIONAL SEARCH REPORT International application No. PCTIAlf 94100773 C(Continuation). DOCUMENTS CONSIDERED TO BE RELEVANTI Category A Citation of document, with indication, where appropriate of the relevant passages Relevant to Claim No. US,A, 4404329 (MAEDA et al) 13 September 1983 (13.09.83) see whole document Form PCT/ISA/210 (continuation of second sheet)(July 1992) cophin I I INTERNATIONAL SEARCH REPORT Inlbi .atuon onpatent family Inembe International application No, PCT/AU 94/00773 This Annex lists the known publication level patent family members relating to the patent documents cited in the above-mentioned international search report. The Australian Patent Office is in no way liable for these particulars which are merely given for the purpose of information. Patent Document Cited in Search Patent Family Member Report EP 531788 DE 4129741 JP 5194: 01 US 5051480 BR 9005147 CA 2027666 EP 424348 JP 3139549 US 4591615 CA 1243794 EP 154453 ES 541340 ES 8603531 GB 8405190 JP 60210637 US 4404329 DE 2913992 FR 2421923 IT 7921669 IT 1115161 JP 54132647 JP 61001467 END OF ANNEX Form PCT/ISA/210(patent family annex)(July 1992) cophin i I