CA1190985A - Antioxidant system for use in the simultaneous injection of a liquid organic peroxide cross-linking agent for the production of cross-linked polyolefin products - Google Patents
Antioxidant system for use in the simultaneous injection of a liquid organic peroxide cross-linking agent for the production of cross-linked polyolefin productsInfo
- Publication number
- CA1190985A CA1190985A CA000426950A CA426950A CA1190985A CA 1190985 A CA1190985 A CA 1190985A CA 000426950 A CA000426950 A CA 000426950A CA 426950 A CA426950 A CA 426950A CA 1190985 A CA1190985 A CA 1190985A
- Authority
- CA
- Canada
- Prior art keywords
- antioxidant
- cross
- organic peroxide
- linking agent
- production
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K5/00—Use of organic ingredients
- C08K5/04—Oxygen-containing compounds
- C08K5/13—Phenols; Phenolates
- C08K5/134—Phenols containing ester groups
- C08K5/1345—Carboxylic esters of phenolcarboxylic acids
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K5/00—Use of organic ingredients
- C08K5/36—Sulfur-, selenium-, or tellurium-containing compounds
- C08K5/37—Thiols
- C08K5/372—Sulfides, e.g. R-(S)x-R'
Landscapes
- Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Compositions Of Macromolecular Compounds (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE:
A method of fabricating extruded products made of crosslinked polyolefin compositions, wherein organic peroxide is introduced, as a crosslinking agent, at the inlet of an extruder simultaneously with the polyolefin composition and an antioxidant, is disclosed The antioxidant is a system comprising n-octadecyl, 3-5-di-t-butyl-4-hydroxy-hydrocinnamate, as the primary antioxidant, and di(tri-decyl) thiodipropionate, as a synergistic antioxidant.
A method of fabricating extruded products made of crosslinked polyolefin compositions, wherein organic peroxide is introduced, as a crosslinking agent, at the inlet of an extruder simultaneously with the polyolefin composition and an antioxidant, is disclosed The antioxidant is a system comprising n-octadecyl, 3-5-di-t-butyl-4-hydroxy-hydrocinnamate, as the primary antioxidant, and di(tri-decyl) thiodipropionate, as a synergistic antioxidant.
Description
9~35 ANTIOXIDANT SYSTEM FO~ USE IN T~E
SIMULTANEOUS INJECTION OF A LIQUID
ORGANIC PEROXIDE CROSS-LINKING AGENT
FOR THE PRODUCTION OF CROSS-LINKED
P~LYOLEF:IN PRODUCTS
__ _ _ This inven-tion relates to the fabrication of extruded products made of polyolefin compositions~ and more particularly to the fabrication of insulating or semi-conducting sheathing layers on electric cablesO
S The compositions which are commonly used in the making of high voltage cable extruded insulation are the compositions based on olef:inic polymers such as polypropylenes, the copolymers and terpolymers such as ethylene-propylene copolymer (EP.M), ethylene-propylene-diene terpolymers (EPDM) and the ethylene-vinyl acetate copolymers (EVA), and mixtures wherein one of the basic products is an ethylene polymer.
The above polyolefin compositions are extruded and then cross-linked to attain the temperature rating of 90C and emergency rating of 130C.
One method of crosslinking consists of incorpo-rating a cross-linking agent such as an organic liquid peroxide directly at the inlet of an extruder simulta-neously with the polyolefin composition and a specific antioxidant.
The antioxidants employed in thermosetting polyolefinic compositions, crosslinked by organic peroxide, consist of phenolic type oxidation inhibitors which render the insulation capable to withstand the high temperature service condition without excessive ,~
oxidative deterioration~ Furthermore they must not inhibit the crosslinking reaction and withstand the high tem peratures employed in crosslinking process.
In case of peroxide injection process when the antioxidant is injected together with peroxide, the anti-oxidant must possess the following additional character-lstics:
lo It must be soluble in a given peroxide in quantities required by the properties o~ the cable insulation.
SIMULTANEOUS INJECTION OF A LIQUID
ORGANIC PEROXIDE CROSS-LINKING AGENT
FOR THE PRODUCTION OF CROSS-LINKED
P~LYOLEF:IN PRODUCTS
__ _ _ This inven-tion relates to the fabrication of extruded products made of polyolefin compositions~ and more particularly to the fabrication of insulating or semi-conducting sheathing layers on electric cablesO
S The compositions which are commonly used in the making of high voltage cable extruded insulation are the compositions based on olef:inic polymers such as polypropylenes, the copolymers and terpolymers such as ethylene-propylene copolymer (EP.M), ethylene-propylene-diene terpolymers (EPDM) and the ethylene-vinyl acetate copolymers (EVA), and mixtures wherein one of the basic products is an ethylene polymer.
The above polyolefin compositions are extruded and then cross-linked to attain the temperature rating of 90C and emergency rating of 130C.
One method of crosslinking consists of incorpo-rating a cross-linking agent such as an organic liquid peroxide directly at the inlet of an extruder simulta-neously with the polyolefin composition and a specific antioxidant.
The antioxidants employed in thermosetting polyolefinic compositions, crosslinked by organic peroxide, consist of phenolic type oxidation inhibitors which render the insulation capable to withstand the high temperature service condition without excessive ,~
oxidative deterioration~ Furthermore they must not inhibit the crosslinking reaction and withstand the high tem peratures employed in crosslinking process.
In case of peroxide injection process when the antioxidant is injected together with peroxide, the anti-oxidant must possess the following additional character-lstics:
lo It must be soluble in a given peroxide in quantities required by the properties o~ the cable insulation.
2~ It must exhibit no tendency to stick to the internal surfaces of an extruder - the phenomenon known under the term "plate-out".
U.S. Patent 4,221,699 issued on September 9, 1980, to Societe ~nonyme de Telecommunications discloses that improved results have been obtained by using a special type of thio-bisphenol antioxidant having a melting point less than 125C and of the general formula:
(RlC H - RllOH) Sx wherein x is a ~hole number e~ual to 1, 2 or 3, and and R~l are each alkyl, preferably C to C and most prefer~bly ethyl, methyl or tertbutyl groups. ~ha preferred antioxidant is 2,2 - thio-bis (6-t-butyl-p-cresol) manufactured by Ciba-Geigy under the trade-Mark Irganox 1081 and having a melting point of about 85C. It is disclosed in the above U.S. Patent 4,221,699 that the melting point of the antioxidant must be less than 125C
g~
in order to avoid deposit of polyolefin composition in the extruder (plate-out1 and production o irregu-larities and Eailures in the extruded material. It is mentioned in the above patent that the use of the anti~
oxidant 4'4 thio-bis (6-t-butyl-m-cresol) sold by Monsanto Chemical under the trademark Santonox R and having a melting point of 158aC has resulted in the above plate out problem.
The applicant has surprisingly discovered that an improved stabilizing effect on polyolefin can be obtained with an antioxidant system comprising n-octadecyl,
U.S. Patent 4,221,699 issued on September 9, 1980, to Societe ~nonyme de Telecommunications discloses that improved results have been obtained by using a special type of thio-bisphenol antioxidant having a melting point less than 125C and of the general formula:
(RlC H - RllOH) Sx wherein x is a ~hole number e~ual to 1, 2 or 3, and and R~l are each alkyl, preferably C to C and most prefer~bly ethyl, methyl or tertbutyl groups. ~ha preferred antioxidant is 2,2 - thio-bis (6-t-butyl-p-cresol) manufactured by Ciba-Geigy under the trade-Mark Irganox 1081 and having a melting point of about 85C. It is disclosed in the above U.S. Patent 4,221,699 that the melting point of the antioxidant must be less than 125C
g~
in order to avoid deposit of polyolefin composition in the extruder (plate-out1 and production o irregu-larities and Eailures in the extruded material. It is mentioned in the above patent that the use of the anti~
oxidant 4'4 thio-bis (6-t-butyl-m-cresol) sold by Monsanto Chemical under the trademark Santonox R and having a melting point of 158aC has resulted in the above plate out problem.
The applicant has surprisingly discovered that an improved stabilizing effect on polyolefin can be obtained with an antioxidant system comprising n-octadecyl,
3,5-di-t-butyl-4-hydroxy-hydrocinnamate as the primary antioxidant and di (tri-decyl) thiodipropionate as a synergistic antioxidant. Furthermore the cost of the above system is lower than the thio-bisphenol antioxidant mentioned previously.
The above primary antioxidant is sold by Ciba-Geigy under the Trade-Mark Irganox 1076 and has a melting point of 50-55C. The synergist is a liquid marketed under the 2Q name Di (tridecyl) thiodipropionate by Evans Chemetics, Inc.
The primary antioxidant used in the present invention is in a predetermined proportion of 0O15 to QO3%~ preferably about 0.2~ by weight of the polyolefin.
The synergistic antioxidant is used in proportion of Q~2 0.8~, preferably 0.4-0O8~ by weight of the polyolefin.
The primary antioxidant and the synergistic antioxidant are prefexably first dissolved in the peroxide and then blended ~ith the polvolefin composition in the extruder.
Comparative accelerated aging tests have been carried out using a commercial crosslinked polyethylene (XLPE) slab sample and various polyethylene slab samples stabilized by Santonox R, Irganox 1081, Irganox 1076 alone, and the antioxidant system in accordance wi-th the present invention. The commercial XLPE slab sample was Union Carbide's HFDE #4201, t~e other slab samples consisted of low density polyethylene which was crosslinked hy using an organic peroxide, namely di-t butyl peroxide. The antioxidants were first dissolved in the peroxide and then blended with the polyethylene. The mixtures were then cured in a heated mold. The slab samples were oven aged for up to two weeks at 158C, and were tested periodically as in the following Table.
~.9~3g~5 Resul~s from the Evaluaeion of ~he A~tioxidant ~ ~ . . .
On Sla~ S_ ples at 158C
.... _ _ _ _ _ .. _ . .. -Physicals and Percentage of Retention After ~ging Antloxidant Uhag~d Physicals _ Additional FormMlaticsl _ _ _ 5 Days 7 Day9 ~ging (Wt. ~ of Tensile _ _ ~ _ Polyethylene) FlongatiQn Strength E T.S. E T,S. E I T.S
~O (p9i) (O (p9i) (~i) (p~i) (O (p9i ._._ . ... _ .____ _ _ _ ___ CommQr~ial ~LPh' 530 2626 _ ~ S35 2608 ~7 1159 (101~(99)~44~ (l~j (9 days) 2~0~ PQt~3xide 0.153 Irganox 1076 517 2062 _ _ 100 1039 0.45% DTDTDP . (19)(50) r~egraded 2.0~ Percxide i 0.2~ I~ganox 1076 537 2401 _ - I 37 695 0.2~ DTDTDP (7) (29)DY rraded 2.0% Peo~cide 0.2% Irganox 1076 583 2154 _ _ 610 2320 60 799 0.4% DTDTDP (105)(108)(13) (371 l (13 ~ays) 2.0~ Peroxide 0.2% Ixyanox 1076 595 2076 _ _ 657 2445 62 848 0.6% DTDTDP (110)(118)(10) (41) (13 1ays) 2.0~ Fer2xiQ~
0.2~ Irganox 1076 598 2174 _ _ 662 2437 31 950 0.8~ DTOIDP (111)(112)(14) (44) (12 day9) 2.0~ Peroxide 5S0 2490 55 948 0.2~ Irganox 1081 (10) (38) ~egraded 2.0% Peroxide 540 2535 483 1784 0.2% Santonox R (89) (70) De3raded 560 2760 ~ ~ ~ -otes: 1. Percentages of retention of unaged values are shown in parentheses.
2. Di (tridecyl) thiodipropionate is abbreviated DTDTDP
It is seen fxom t.he results of the above test that the antiox.idant system in accordance with the present invention is more reslstant to accelerated aging tests at 158C than Irganox la81 and Santanox Ro The best results are obtained when the primary antioxidant Irganox lQ76 is used in the proportion of about 0.2 weight ~ of the polyethylene and the synergistic antioxidant in the p~ortion of 0~4 to 0.8 wei~ht % of the polyethylene.
It will also be noted that Irganox 1076 used alone without the synergistic antioxidant has substantially lower retention of ~h~ mechanical characteristics.
The.above aging tests have also revealed that the level of the primary antioxidant should be higher than 0.15 weight % of the polyethylene and the level of the synergist higher than 0.2 weight % of the polyethylene.
The upper limit of the primary antioxidant should be about 0.3 weight % of the polyethylene as no significant improvement in oven aging properties are expected above that value but there is a chance of precipitation of the antioxidant from the solution at high temperature. In addition the cost of the antioxidant is obviously higher.
Similarly, no improved results are expected with the use of the synergist in higher quantities than 0.8 weight %
of the polyethylene.
Based on the use of the above mentioned preferred proportions of Irganox 1076 and the synergist Di (tridecyl) -thiodiproplonate, the cost of the new antioxidant system is approximately 50~ less than that of using 0.2~ by weight of Irganox 1~81.
The above primary antioxidant is sold by Ciba-Geigy under the Trade-Mark Irganox 1076 and has a melting point of 50-55C. The synergist is a liquid marketed under the 2Q name Di (tridecyl) thiodipropionate by Evans Chemetics, Inc.
The primary antioxidant used in the present invention is in a predetermined proportion of 0O15 to QO3%~ preferably about 0.2~ by weight of the polyolefin.
The synergistic antioxidant is used in proportion of Q~2 0.8~, preferably 0.4-0O8~ by weight of the polyolefin.
The primary antioxidant and the synergistic antioxidant are prefexably first dissolved in the peroxide and then blended ~ith the polvolefin composition in the extruder.
Comparative accelerated aging tests have been carried out using a commercial crosslinked polyethylene (XLPE) slab sample and various polyethylene slab samples stabilized by Santonox R, Irganox 1081, Irganox 1076 alone, and the antioxidant system in accordance wi-th the present invention. The commercial XLPE slab sample was Union Carbide's HFDE #4201, t~e other slab samples consisted of low density polyethylene which was crosslinked hy using an organic peroxide, namely di-t butyl peroxide. The antioxidants were first dissolved in the peroxide and then blended with the polyethylene. The mixtures were then cured in a heated mold. The slab samples were oven aged for up to two weeks at 158C, and were tested periodically as in the following Table.
~.9~3g~5 Resul~s from the Evaluaeion of ~he A~tioxidant ~ ~ . . .
On Sla~ S_ ples at 158C
.... _ _ _ _ _ .. _ . .. -Physicals and Percentage of Retention After ~ging Antloxidant Uhag~d Physicals _ Additional FormMlaticsl _ _ _ 5 Days 7 Day9 ~ging (Wt. ~ of Tensile _ _ ~ _ Polyethylene) FlongatiQn Strength E T.S. E T,S. E I T.S
~O (p9i) (O (p9i) (~i) (p~i) (O (p9i ._._ . ... _ .____ _ _ _ ___ CommQr~ial ~LPh' 530 2626 _ ~ S35 2608 ~7 1159 (101~(99)~44~ (l~j (9 days) 2~0~ PQt~3xide 0.153 Irganox 1076 517 2062 _ _ 100 1039 0.45% DTDTDP . (19)(50) r~egraded 2.0~ Percxide i 0.2~ I~ganox 1076 537 2401 _ - I 37 695 0.2~ DTDTDP (7) (29)DY rraded 2.0% Peo~cide 0.2% Irganox 1076 583 2154 _ _ 610 2320 60 799 0.4% DTDTDP (105)(108)(13) (371 l (13 ~ays) 2.0~ Peroxide 0.2% Ixyanox 1076 595 2076 _ _ 657 2445 62 848 0.6% DTDTDP (110)(118)(10) (41) (13 1ays) 2.0~ Fer2xiQ~
0.2~ Irganox 1076 598 2174 _ _ 662 2437 31 950 0.8~ DTOIDP (111)(112)(14) (44) (12 day9) 2.0~ Peroxide 5S0 2490 55 948 0.2~ Irganox 1081 (10) (38) ~egraded 2.0% Peroxide 540 2535 483 1784 0.2% Santonox R (89) (70) De3raded 560 2760 ~ ~ ~ -otes: 1. Percentages of retention of unaged values are shown in parentheses.
2. Di (tridecyl) thiodipropionate is abbreviated DTDTDP
It is seen fxom t.he results of the above test that the antiox.idant system in accordance with the present invention is more reslstant to accelerated aging tests at 158C than Irganox la81 and Santanox Ro The best results are obtained when the primary antioxidant Irganox lQ76 is used in the proportion of about 0.2 weight ~ of the polyethylene and the synergistic antioxidant in the p~ortion of 0~4 to 0.8 wei~ht % of the polyethylene.
It will also be noted that Irganox 1076 used alone without the synergistic antioxidant has substantially lower retention of ~h~ mechanical characteristics.
The.above aging tests have also revealed that the level of the primary antioxidant should be higher than 0.15 weight % of the polyethylene and the level of the synergist higher than 0.2 weight % of the polyethylene.
The upper limit of the primary antioxidant should be about 0.3 weight % of the polyethylene as no significant improvement in oven aging properties are expected above that value but there is a chance of precipitation of the antioxidant from the solution at high temperature. In addition the cost of the antioxidant is obviously higher.
Similarly, no improved results are expected with the use of the synergist in higher quantities than 0.8 weight %
of the polyethylene.
Based on the use of the above mentioned preferred proportions of Irganox 1076 and the synergist Di (tridecyl) -thiodiproplonate, the cost of the new antioxidant system is approximately 50~ less than that of using 0.2~ by weight of Irganox 1~81.
Claims (5)
1. In a method of fabricating extruded products made of crosslinked polyolefin compositions, wherein organic peroxide is introduced, as a crosslinking agent, at the inlet of an extruder simultaneously with the polyolefin composition and an antioxidant, the improvement comprising using as the said antioxidant a system comprising n-octadecyl, 3-5-di-t-butyl-4-hydroxy-hydrocinnamate, as the primary antioxidant, and di (tri-decyl)thiodipropionate, as a synergistic antioxidant.
2. A method as defined in Claim 1, wherein the primary antioxidant is used in a proportion of about 0.15 - 0.3%
by weight of the polyolefin composition.
by weight of the polyolefin composition.
3. A method as defined in Claim 2, wherein the synergistic antioxidant is used in a proportion of 0.2 -0.8% by weight of the polyolefin composition.
4. A method as defined in Claim 1, wherein the primary antioxidant is used in a proportion of about 0.2%, and the synergistic antioxidant is used in a proportion of about 0.4 - 0.8%.
5. A method as defined in Claim 1, wherein the anti-oxidant system is first dissolved in the peroxide and then blended with the polyolefin composition.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000426950A CA1190985A (en) | 1983-04-28 | 1983-04-28 | Antioxidant system for use in the simultaneous injection of a liquid organic peroxide cross-linking agent for the production of cross-linked polyolefin products |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000426950A CA1190985A (en) | 1983-04-28 | 1983-04-28 | Antioxidant system for use in the simultaneous injection of a liquid organic peroxide cross-linking agent for the production of cross-linked polyolefin products |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1190985A true CA1190985A (en) | 1985-07-23 |
Family
ID=4125120
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000426950A Expired CA1190985A (en) | 1983-04-28 | 1983-04-28 | Antioxidant system for use in the simultaneous injection of a liquid organic peroxide cross-linking agent for the production of cross-linked polyolefin products |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1190985A (en) |
-
1983
- 1983-04-28 CA CA000426950A patent/CA1190985A/en not_active Expired
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Legal Events
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|---|---|---|---|
| MKEC | Expiry (correction) | ||
| MKEX | Expiry |