CA1036537A - Modified polyethylene having an increased cross-linking yield when subjected to gamma ray radiation and process for the preparation thereof - Google Patents
Modified polyethylene having an increased cross-linking yield when subjected to gamma ray radiation and process for the preparation thereofInfo
- Publication number
- CA1036537A CA1036537A CA156,761A CA156761A CA1036537A CA 1036537 A CA1036537 A CA 1036537A CA 156761 A CA156761 A CA 156761A CA 1036537 A CA1036537 A CA 1036537A
- Authority
- CA
- Canada
- Prior art keywords
- linking
- polyethylene
- gamma ray
- cross
- increased cross
- 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
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J3/00—Processes of treating or compounding macromolecular substances
- C08J3/28—Treatment by wave energy or particle radiation
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2323/00—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers
- C08J2323/02—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers not modified by chemical after treatment
- C08J2323/04—Homopolymers or copolymers of ethene
- C08J2323/08—Copolymers of ethene
Landscapes
- Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Processes Of Treating Macromolecular Substances (AREA)
- Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
- Graft Or Block Polymers (AREA)
- Treatments Of Macromolecular Shaped Articles (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
The present invention is directed to a process for the production of polyethylene having an increased cross-linking yield which comprises cross-linking a copolymer constituted by ethylene and an amount of butadiene lower than 5% by weight, in the presence of gamma ray radiations applied within a relatively short period of treating time,the polyethylene thus obtained being slightly modified by the very little amount of polybutadiene.
In the above process, the amount of radiant energy required is reduced.
The present invention is directed to a process for the production of polyethylene having an increased cross-linking yield which comprises cross-linking a copolymer constituted by ethylene and an amount of butadiene lower than 5% by weight, in the presence of gamma ray radiations applied within a relatively short period of treating time,the polyethylene thus obtained being slightly modified by the very little amount of polybutadiene.
In the above process, the amount of radiant energy required is reduced.
Description
The present invention is concerned wi-th a process for the production of polyethylene having an increased cross-linking yield, by the cross-linking o~ an ethylene-butadiene copolymer, ~
in the presence of gamma ray radiations applied within a relatively :
short period of treating time.
. .
It is known~that polyethylene may be cross-linked by gamma ray radiation, and that the cross-linking remarkably ~.
increases the mechanical properties such as impact strength, room ageing resistance and abrasion resistance. ~
Generally, the radiation requires a high amount of energy .
and quite long treating times, which weighs heavily on the cost of the product and the economy of the process.
We have now ~ound, and this is the main object of the present invention, that it is possible to remarkably de~rease the production time or the amount of radiant energy emp~oyecl by irra-diating a modi~ied polyethylene copolymer conta.inincJ butadien~ in an amount less than 5~ by weight. '~he polyethylene obtained is only slightly modified by the very little amount of polybutadiene. `~
The radiation can be performed by employing any source or any type of radiation. The particular use of gamma rays is suggested because it enables one to make comparison with the prior art.
The polymers so obtained can be cross-linked by : :
utilizing lower doses than in the case of usual polyethylene and ~ ::
give rise to products which may be exemplified by -(I) completely cross-linked polyethylenes which are :
consequently no more thermoplastic, and possess radiation times shorter than usual polyethylene.
'
in the presence of gamma ray radiations applied within a relatively :
short period of treating time.
. .
It is known~that polyethylene may be cross-linked by gamma ray radiation, and that the cross-linking remarkably ~.
increases the mechanical properties such as impact strength, room ageing resistance and abrasion resistance. ~
Generally, the radiation requires a high amount of energy .
and quite long treating times, which weighs heavily on the cost of the product and the economy of the process.
We have now ~ound, and this is the main object of the present invention, that it is possible to remarkably de~rease the production time or the amount of radiant energy emp~oyecl by irra-diating a modi~ied polyethylene copolymer conta.inincJ butadien~ in an amount less than 5~ by weight. '~he polyethylene obtained is only slightly modified by the very little amount of polybutadiene. `~
The radiation can be performed by employing any source or any type of radiation. The particular use of gamma rays is suggested because it enables one to make comparison with the prior art.
The polymers so obtained can be cross-linked by : :
utilizing lower doses than in the case of usual polyethylene and ~ ::
give rise to products which may be exemplified by -(I) completely cross-linked polyethylenes which are :
consequently no more thermoplastic, and possess radiation times shorter than usual polyethylene.
'
- 2 -- lQ36S3~
- The cross~linked polyethylenes are useful for making electric cables or other appliances involving possible superheating;
(II) partially cross-linked polyethylenes having improved properties such as impact, stress cracking, with respect to the s-tarting product.
The butadiene amounts present in the polymer chain are generally small, since they must not jeopardize the fundamental -polyethylene nature of the product.
The introduction o~ the small amounts o~ butacliene indi-cated above is performed by the method well known to those skilled ..
in the art.
The copolymerization process described and claimed by the Applicant is Canadian Patent No. 914,3~6 can be used with advantage. ~ccording to that process, it is possible to obta:Ln copolymers oE an ol~Ein and a diolc~in aonta.in:incJ :E.rom the lowest amount up to 95~ of diole~in by operating in the presence o~ ca~
talysts consisting of vanadium compounds o~ the formulae :
V (NR2~4 or V (NR2)2 X2 in which R is an alkyl or cycloalkyl ra- ; :
dical and X is halogen, and aluminum compounds of the ~ormula Al Rn X3 n wherein R and X have the above meaning and 1 ~ n ~ 2. ~.
. The process according to the invention will be more clearly explained by examining the following non-restrictive examples.
A.comparison is made therein between the cross-linking ..
ratios (expressed as % gel~ of ethylene-butadiene copolymers and high density polyethylenes using the same dose of irradiation .
and possessing the same intrinsic viscosity.
In all cases there is observed an improved yield oE cross~
linking ~or the copolymers with. respect to polyethylene homopolymers treated under the same conditions. This e~ect is attributable to khe presence of unsaturations in the ethylene-butadiene copolymers. ~.
~ - 3 - ~ ~.
~C " '' ', C~ . " ' .
1~3~S37 In the present case the gamma radiations are supplied by fuel elements (enriched uranium) which are already utilized in nuclear reactors.
The dose measurement (radiation x time) was performed ~.~36S37 by an oxalic acid de-tector, The cross-linking ratio is expressed as polymer gel after extraction in boiling xylene at 140C for 20 hours~
'llhe intrinsic viscosity was measured in decalin at 135C. .
EXAM
'~he same dose was used (2 Mrad) fo~ irradiating a high den~ity polyethylene ana anethyle.ne-butadiene copolymer having the ~ame intrin~ic viscosity.
The results reported in the table show the adva.ntage of the ethylene-butadiene copolymer: ;
Polymer.% butadie.ne r~l 9tarting % gel after ~ : .
(weight) . L J radiatio~
~ ., _ _ " , Polyethylene 0 2.5 Eth~lene~buta- ~
diene copoly- ~ `
rner 1~3 2,73 . 24 EXAMP~E 2 . . .
The same dose was used (2 Mrad) for irradiating -two ethylene-butadiene copolymers contai.ning differen-t percentage9 of `
butadiene, 20'~he table shows how the higher amount o~ butadiene ~a- ;.. :.
vours cross-linking in the case of the polymer E~ 53 which, on the contrary, would not seem to be faYoured because of its :~ :
lower intrinsic viscosity~
Polymer ,~ butadiene r~ starting % gel after (weight) L J radiation .... . _ .Et.hylene-bu-tadiene oo-polymer 0.8 1.50 0 ;.
" 1.3 1.08 10 ~ ....... _ _ ~___ . . ,_ .. _. . .. .. .
~YAMPLE 3 Three doses (2, 7 and 21 Mrad) were used ~or irradia-ting a commercial high density polyethylene (Vestolen 6013 produ- :
- 4 - ,. -.
: .
~L~36S3'7 ced by Chemische Werke H~ls - trademark) and an ethylene-butadiene copolymer.
~he advantages of the copolymer in regard to the cross-linking yield under any dose are showed by the table: -Polymer % butadiene C~ starting ~ gel a~ter (weight) radiation .. .,, .. . . . ... .. . . . . .... . _ .
Vestolen 6013 irr.
2 Mrad 0 1.85 0 ~estolen 601~ irr.
7 Mrad 1.85 44 Vestolen 6013 irr. ~ ~
21 Mrad 0 1.85 6~ -Ethylene-buta-diene co-polymer irr.
2 Mrad 0.8 2.00 5 ~thyle~e-bu-tadiene co-polymer irr.
7 Mrad 0.8 2.00 70 ~thylene-bu- `~
tadiene co-polymer irr.
21 Mrad 0.8 2.00 98 ~ 5 ~
,
- The cross~linked polyethylenes are useful for making electric cables or other appliances involving possible superheating;
(II) partially cross-linked polyethylenes having improved properties such as impact, stress cracking, with respect to the s-tarting product.
The butadiene amounts present in the polymer chain are generally small, since they must not jeopardize the fundamental -polyethylene nature of the product.
The introduction o~ the small amounts o~ butacliene indi-cated above is performed by the method well known to those skilled ..
in the art.
The copolymerization process described and claimed by the Applicant is Canadian Patent No. 914,3~6 can be used with advantage. ~ccording to that process, it is possible to obta:Ln copolymers oE an ol~Ein and a diolc~in aonta.in:incJ :E.rom the lowest amount up to 95~ of diole~in by operating in the presence o~ ca~
talysts consisting of vanadium compounds o~ the formulae :
V (NR2~4 or V (NR2)2 X2 in which R is an alkyl or cycloalkyl ra- ; :
dical and X is halogen, and aluminum compounds of the ~ormula Al Rn X3 n wherein R and X have the above meaning and 1 ~ n ~ 2. ~.
. The process according to the invention will be more clearly explained by examining the following non-restrictive examples.
A.comparison is made therein between the cross-linking ..
ratios (expressed as % gel~ of ethylene-butadiene copolymers and high density polyethylenes using the same dose of irradiation .
and possessing the same intrinsic viscosity.
In all cases there is observed an improved yield oE cross~
linking ~or the copolymers with. respect to polyethylene homopolymers treated under the same conditions. This e~ect is attributable to khe presence of unsaturations in the ethylene-butadiene copolymers. ~.
~ - 3 - ~ ~.
~C " '' ', C~ . " ' .
1~3~S37 In the present case the gamma radiations are supplied by fuel elements (enriched uranium) which are already utilized in nuclear reactors.
The dose measurement (radiation x time) was performed ~.~36S37 by an oxalic acid de-tector, The cross-linking ratio is expressed as polymer gel after extraction in boiling xylene at 140C for 20 hours~
'llhe intrinsic viscosity was measured in decalin at 135C. .
EXAM
'~he same dose was used (2 Mrad) fo~ irradiating a high den~ity polyethylene ana anethyle.ne-butadiene copolymer having the ~ame intrin~ic viscosity.
The results reported in the table show the adva.ntage of the ethylene-butadiene copolymer: ;
Polymer.% butadie.ne r~l 9tarting % gel after ~ : .
(weight) . L J radiatio~
~ ., _ _ " , Polyethylene 0 2.5 Eth~lene~buta- ~
diene copoly- ~ `
rner 1~3 2,73 . 24 EXAMP~E 2 . . .
The same dose was used (2 Mrad) for irradiating -two ethylene-butadiene copolymers contai.ning differen-t percentage9 of `
butadiene, 20'~he table shows how the higher amount o~ butadiene ~a- ;.. :.
vours cross-linking in the case of the polymer E~ 53 which, on the contrary, would not seem to be faYoured because of its :~ :
lower intrinsic viscosity~
Polymer ,~ butadiene r~ starting % gel after (weight) L J radiation .... . _ .Et.hylene-bu-tadiene oo-polymer 0.8 1.50 0 ;.
" 1.3 1.08 10 ~ ....... _ _ ~___ . . ,_ .. _. . .. .. .
~YAMPLE 3 Three doses (2, 7 and 21 Mrad) were used ~or irradia-ting a commercial high density polyethylene (Vestolen 6013 produ- :
- 4 - ,. -.
: .
~L~36S3'7 ced by Chemische Werke H~ls - trademark) and an ethylene-butadiene copolymer.
~he advantages of the copolymer in regard to the cross-linking yield under any dose are showed by the table: -Polymer % butadiene C~ starting ~ gel a~ter (weight) radiation .. .,, .. . . . ... .. . . . . .... . _ .
Vestolen 6013 irr.
2 Mrad 0 1.85 0 ~estolen 601~ irr.
7 Mrad 1.85 44 Vestolen 6013 irr. ~ ~
21 Mrad 0 1.85 6~ -Ethylene-buta-diene co-polymer irr.
2 Mrad 0.8 2.00 5 ~thyle~e-bu-tadiene co-polymer irr.
7 Mrad 0.8 2.00 70 ~thylene-bu- `~
tadiene co-polymer irr.
21 Mrad 0.8 2.00 98 ~ 5 ~
,
Claims
The embodiments of the invention in which an exlcusive property or privilege is claimed are defined as follows:
Process for the production of polyethylene having an increased cross-linking yield, which comprises cross-linking an ethylene-butadiene copolymer containing butadiene in an amount less than 5% by weight, in the presence of gamma ray radiations applied within a relatively short period of treating time, the polyethylene thus obtained being slightly modified by the very little amount of polybutadiene.
Process for the production of polyethylene having an increased cross-linking yield, which comprises cross-linking an ethylene-butadiene copolymer containing butadiene in an amount less than 5% by weight, in the presence of gamma ray radiations applied within a relatively short period of treating time, the polyethylene thus obtained being slightly modified by the very little amount of polybutadiene.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| IT3173371A IT946108B (en) | 1971-11-26 | 1971-11-26 | MODIFIED POLYETHYLENE WITH INCREASED CROSS-LINKING PERFORMANCE BY IRRADICULATION WITH GAMMA RAYS AND PROCEDURE FOR ITS PREPARATION |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1036537A true CA1036537A (en) | 1978-08-15 |
Family
ID=11234289
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA156,761A Expired CA1036537A (en) | 1971-11-26 | 1972-11-15 | Modified polyethylene having an increased cross-linking yield when subjected to gamma ray radiation and process for the preparation thereof |
Country Status (15)
| Country | Link |
|---|---|
| JP (1) | JPS5321034B2 (en) |
| BE (1) | BE791711A (en) |
| CA (1) | CA1036537A (en) |
| CH (1) | CH556362A (en) |
| CS (1) | CS159203B2 (en) |
| DD (1) | DD103452A5 (en) |
| DE (1) | DE2257111A1 (en) |
| ES (1) | ES409253A1 (en) |
| FR (1) | FR2160937B1 (en) |
| GB (1) | GB1378978A (en) |
| IT (1) | IT946108B (en) |
| LU (1) | LU66526A1 (en) |
| NL (1) | NL7215787A (en) |
| RO (1) | RO62463A (en) |
| SU (1) | SU673178A3 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS55118767U (en) * | 1979-02-16 | 1980-08-22 | ||
| US4264490A (en) * | 1979-05-11 | 1981-04-28 | Radiation Dynamics, Inc. | Composition of a polyethylene and isobutylene copolymer |
-
0
- BE BE791711D patent/BE791711A/en unknown
-
1971
- 1971-11-26 IT IT3173371A patent/IT946108B/en active
- 1971-11-26 RO RO710072943A patent/RO62463A/en unknown
-
1972
- 1972-11-15 CA CA156,761A patent/CA1036537A/en not_active Expired
- 1972-11-21 DE DE19722257111 patent/DE2257111A1/en active Pending
- 1972-11-22 FR FR7241404A patent/FR2160937B1/fr not_active Expired
- 1972-11-22 GB GB5410072A patent/GB1378978A/en not_active Expired
- 1972-11-22 NL NL7215787A patent/NL7215787A/xx unknown
- 1972-11-22 SU SU721847809A patent/SU673178A3/en active
- 1972-11-23 ES ES409253A patent/ES409253A1/en not_active Expired
- 1972-11-23 DD DD16713372A patent/DD103452A5/xx unknown
- 1972-11-24 CS CS803372A patent/CS159203B2/cs unknown
- 1972-11-24 LU LU66526D patent/LU66526A1/xx unknown
- 1972-11-25 CH CH1719872A patent/CH556362A/en not_active IP Right Cessation
- 1972-11-27 JP JP11813772A patent/JPS5321034B2/ja not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| CH556362A (en) | 1974-11-29 |
| IT946108B (en) | 1973-05-21 |
| DE2257111A1 (en) | 1973-05-30 |
| GB1378978A (en) | 1975-01-02 |
| FR2160937B1 (en) | 1975-03-28 |
| SU673178A3 (en) | 1979-07-05 |
| DD103452A5 (en) | 1974-01-20 |
| FR2160937A1 (en) | 1973-07-06 |
| LU66526A1 (en) | 1973-02-01 |
| JPS4860746A (en) | 1973-08-25 |
| ES409253A1 (en) | 1975-12-01 |
| CS159203B2 (en) | 1974-12-27 |
| RO62463A (en) | 1977-10-15 |
| NL7215787A (en) | 1973-05-29 |
| BE791711A (en) | 1973-03-16 |
| JPS5321034B2 (en) | 1978-06-30 |
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