CA1055642A - Vulcanizable ethylene polymer composition with allyl compounds and process for avoiding scorching thereof - Google Patents
Vulcanizable ethylene polymer composition with allyl compounds and process for avoiding scorching thereofInfo
- Publication number
- CA1055642A CA1055642A CA239,206A CA239206A CA1055642A CA 1055642 A CA1055642 A CA 1055642A CA 239206 A CA239206 A CA 239206A CA 1055642 A CA1055642 A CA 1055642A
- Authority
- CA
- Canada
- Prior art keywords
- composition
- ethylene
- weight
- weight percent
- peroxide
- 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
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B3/00—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties
- H01B3/18—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances
- H01B3/30—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes
- H01B3/44—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes vinyl resins; acrylic resins
- H01B3/441—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances plastics; resins; waxes vinyl resins; acrylic resins from alkenes
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F255/00—Macromolecular compounds obtained by polymerising monomers on to polymers of hydrocarbons as defined in group C08F10/00
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F255/00—Macromolecular compounds obtained by polymerising monomers on to polymers of hydrocarbons as defined in group C08F10/00
- C08F255/02—Macromolecular compounds obtained by polymerising monomers on to polymers of hydrocarbons as defined in group C08F10/00 on to polymers of olefins having two or three carbon atoms
-
- 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
- C08K5/14—Peroxides
Landscapes
- Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Physics & Mathematics (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Compositions Of Macromolecular Compounds (AREA)
- Graft Or Block Polymers (AREA)
- Adhesives Or Adhesive Processes (AREA)
- Organic Insulating Materials (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
Vulacnizable ethylene polymer based compositions which are susceptible to scorching when processed at elevated temperatures, prior to vulcanization, in the presence of certain organic peroxide compounds, are protected against such scorching by the incorporation therein of certain organic hydroperoxide compounds and organic compounds containing at least three allyl groups.
1.
Vulacnizable ethylene polymer based compositions which are susceptible to scorching when processed at elevated temperatures, prior to vulcanization, in the presence of certain organic peroxide compounds, are protected against such scorching by the incorporation therein of certain organic hydroperoxide compounds and organic compounds containing at least three allyl groups.
1.
Description
` r BACKGROU~D OF THE INVE~TION
Field o-f the Invention The invention relates to the prevention of scorching, prior to v~llcanization, of peroxide curable ~:~
ethylene polymer based compositions .
Descri~tion of the Prior Art ..
Insulation compositions which are employed on electrical wire and cable are, in many cases, prepared from compositions which are based on vulcanizable, or cross-linkable, ethylene polyrners~ These ethylene poly-mer based compositions may be vulcanized, or cured, or crossl:Lnked, with various organic peroxide compounds, as disclbsed Eor example in United States Patents, 2,826,570; .. .
Field o-f the Invention The invention relates to the prevention of scorching, prior to v~llcanization, of peroxide curable ~:~
ethylene polymer based compositions .
Descri~tion of the Prior Art ..
Insulation compositions which are employed on electrical wire and cable are, in many cases, prepared from compositions which are based on vulcanizable, or cross-linkable, ethylene polyrners~ These ethylene poly-mer based compositions may be vulcanized, or cured, or crossl:Lnked, with various organic peroxide compounds, as disclbsed Eor example in United States Patents, 2,826,570; .. .
2,888,424; 2,916,481; 3,079,370 and 3,296,189.
In the organic peroxide compounds which have been used to date for commercial purposes in these vul- .
canizable ethylene polymer based compositions, each oxygen atom in the peroxide group, i.e., ~~~ ? oE such compounds is directly attached to a carbon atom oE an organic radical. I'he commercially useful compo~itions do not employ hydroperoxide compounds therein as curing agents because they have relatively high decomposition temperatures, and the free radicals provided by the de-composed hydroperoxides are not effective for cross- -.
linking ethylene polymers.
2. ~ .
~ ~ S S6 ~Z 9751 In order to process the organic peroxide con-taining compositions so as to adapt them to be placed, as insulation, on the electrical conductor components ~ ' of the wire and cable it is usually necessary to admix the components of the compositions at high temperatures, and to extrude them, again at high ternperatures, onto the electrical conductor. These processing activities occur prior to the intended vulcanization of the per-oxide containing compositions, which is usually accomp-lished after such compositions are extruded onto the electrical conductor.
~ t has been found, however, that when certain of the organic peroxide compounds, such as dic~mlyl peroxide, are used in combination with certain t~pes of ethylene polymers or in certain types of ethylene poly-mer based compositions, that the entire curable compo-sition is susceptible to scorching during the high temp-erature processing thereof prior to the vulcanization of the composition on the electrical conductor.
Scorching :Ls, in effect, the premature v~llcanization of the insulation composition. This premature vulcani-zation usually occurs, when it occurs, in the barrel or die head of the extruder in which the insulation composition is being processed, at elevated tempera-tures, prior to its belng extruded onto an electrical conductor, and prior to its intended vulcanization.
;; 3.
:''. `
A
~ 1 , . . .
. ' ' . ~''`' . ' ' '.' ',. ' '"; ~ ;.' . ~ ', ~55G~ 9751 -When an insulation composition is scorched in the extrud-er, the extruded composition will have imperfections in the form o~ discontinuity and roughness in the surface o~ the extrudate; and lumps or surface ripples caused by gel particles in the body of the extrudate. In ~ -addition, excessive scorching may cause enough of a pressure build-up in the extrusion device to require a cessation of the extrusion operation entirely. ; -The tendency o~ a composition to experience scorch is a relative matter, since any vulcanizable ethylene polymer based composition can be made to scorch if processed under conditions designed to produce such result. Under a given set o~ concl:Ltions some compo-sitions are more prone to scorching than are others.
Compositions which ha~e been found to be more susceptible to scorching under a given set o~ conditions are those in which the ethylene polymer has a relatively low melt index and/or a relatively narrow molecular weight distribution.
The tendenc~ o~ a composition to scorch under commercial operating conditions may be measured by means o~ the Monsanto Rheometer Test Procedure. The Monsanto Rheometer Test Procedure is described in ASTM-D-2084-71T.
Prior to the work o~ the present inventor as disclosed in this patent application, and three others , , , . ~ :.
. . " . .. ..
~ 5 S 6 ~ 9751 filed on even date herewith, scorch prevention has been accomplished by the use of additi.~es such as nitrites as disclosed in U.S. 3,202,648; the speci~ic antioxidants.
and vulcanization accelerators disclosed in U.S.
In the organic peroxide compounds which have been used to date for commercial purposes in these vul- .
canizable ethylene polymer based compositions, each oxygen atom in the peroxide group, i.e., ~~~ ? oE such compounds is directly attached to a carbon atom oE an organic radical. I'he commercially useful compo~itions do not employ hydroperoxide compounds therein as curing agents because they have relatively high decomposition temperatures, and the free radicals provided by the de-composed hydroperoxides are not effective for cross- -.
linking ethylene polymers.
2. ~ .
~ ~ S S6 ~Z 9751 In order to process the organic peroxide con-taining compositions so as to adapt them to be placed, as insulation, on the electrical conductor components ~ ' of the wire and cable it is usually necessary to admix the components of the compositions at high temperatures, and to extrude them, again at high ternperatures, onto the electrical conductor. These processing activities occur prior to the intended vulcanization of the per-oxide containing compositions, which is usually accomp-lished after such compositions are extruded onto the electrical conductor.
~ t has been found, however, that when certain of the organic peroxide compounds, such as dic~mlyl peroxide, are used in combination with certain t~pes of ethylene polymers or in certain types of ethylene poly-mer based compositions, that the entire curable compo-sition is susceptible to scorching during the high temp-erature processing thereof prior to the vulcanization of the composition on the electrical conductor.
Scorching :Ls, in effect, the premature v~llcanization of the insulation composition. This premature vulcani-zation usually occurs, when it occurs, in the barrel or die head of the extruder in which the insulation composition is being processed, at elevated tempera-tures, prior to its belng extruded onto an electrical conductor, and prior to its intended vulcanization.
;; 3.
:''. `
A
~ 1 , . . .
. ' ' . ~''`' . ' ' '.' ',. ' '"; ~ ;.' . ~ ', ~55G~ 9751 -When an insulation composition is scorched in the extrud-er, the extruded composition will have imperfections in the form o~ discontinuity and roughness in the surface o~ the extrudate; and lumps or surface ripples caused by gel particles in the body of the extrudate. In ~ -addition, excessive scorching may cause enough of a pressure build-up in the extrusion device to require a cessation of the extrusion operation entirely. ; -The tendency o~ a composition to experience scorch is a relative matter, since any vulcanizable ethylene polymer based composition can be made to scorch if processed under conditions designed to produce such result. Under a given set o~ concl:Ltions some compo-sitions are more prone to scorching than are others.
Compositions which ha~e been found to be more susceptible to scorching under a given set o~ conditions are those in which the ethylene polymer has a relatively low melt index and/or a relatively narrow molecular weight distribution.
The tendenc~ o~ a composition to scorch under commercial operating conditions may be measured by means o~ the Monsanto Rheometer Test Procedure. The Monsanto Rheometer Test Procedure is described in ASTM-D-2084-71T.
Prior to the work o~ the present inventor as disclosed in this patent application, and three others , , , . ~ :.
. . " . .. ..
~ 5 S 6 ~ 9751 filed on even date herewith, scorch prevention has been accomplished by the use of additi.~es such as nitrites as disclosed in U.S. 3,202,648; the speci~ic antioxidants.
and vulcanization accelerators disclosed in U.S.
3,335,124; and the chain transfer agents disclosed in U.S. 3,578,647. ~ mix-ture of two specific peroxides has also been used to provide a rate of cure that is intermediate the rate of cure of either o~ such peroxides, as disclosed in U.S. 3,661,877.
Summary o~ the Invention It has now ~een found that vulcanizable ethylene polymer based compositions which employ certain classes. of organic peroxides therein as vulcanizing .
agents, and which compositions are susceptible to scorching under a given set of conditions, can ~e pro-tected against scorching under such conditi~ns by in-corporating in such compositions certain classes of organic hydroperoxides and organic compounds containing at least three allyl groups.
An object o~ the present invention is to pro-vide scorch resistant, w lcanizable, ethylene polymer based compositions.
Another object of the present invention is ~o provide a process for protecting against scorching vulcanizable ethylene polymer based compositions which employ therein certain classes of organic peroxides as ~5564~ 9751 vulcanizing agents and which are susceptible to scorch-ing.
A further object of the present invention is to provide scorch resistant insulation for electrical wire and cable.
A further object of the present invention is to provide a process whereby vulcanizable ethylene polymer based compositions which employ therein certain classes o~ organic peroxide compounds as vulcanizing agents and which compositions are susceptible to scorch^ `
. .
ing, may be processed in mixing and extruding devices, prior to the vulcanization thereof, at fast throughput rates and at relatively high processing temperatures without experiencing scorching.
These and other objects of the present invention are achieved by employing certain classes of organic~ :
hydroperoxides in combination with organic compounds containing at least three allyl groups as scorch preventing agents in the compositions of the present inventions.
rHE DRAWINGS
Figures 1 and 2 of the drawings show, graphically, Monsanto Rheometer Test curves which were used to illustrate the derivation of an efficiency factbr as described below.
6.
... . .. .. . , ,~ .
. . . . . ' , : , . . . .
, ` ~ S 5~ 42 DESCRIPTION OF THE PREFERRED EMBODIMENT
The Scorch Resistant Composition The scorch resistant compositions of the present invention comprise, in wei.ght ratio, lOQ parts by weight of ethylene polymer, about 0.1 to 5 0, and preferably 0.2 to 2.0, parts by weight of at least one first peroxide compound which has carbon atoms directly bonded to each oxygen atom of each peroxide group (-o-o-) therein, and which compounds, as a class, are described below, about 0.1 to 2.0, and preferably about 0.05 to 1.0, parts by weight of at least one second peroxide compound which i8 a hydroperoxide of the class described below, and about 0.1 to 5.0, and preferably about 0.2 to 2.0 parts by weight of one or more organic compounds containing at least three allyl groups.
About one part by weight of the second peroxide is used per 2 to 10 parts by weight of the first peroxide.
About one part by weight of the allyl compound is used per 1 to 5 parts by weight of the first peroxide .
Ethylene Polymer The ethylene polymers which are used in the compositions of the present invention are solid (at 7.
l B
. . .; . , " i., ..` . .,. ~;" ,~
5 ~ 4~ 9751 ~' , 25C.) materials which may be homopolymers, or copoly-mers of ethylene. The ethylene copolymers contain at least 30 weight percent of ethylene and up to about 70 weight percent of propylene, and/or up to about 50 weight percent of one or more other organic compounds which are interpolymerizable with ethylene.
:; . . .
These other compounds which are interpolymerizable ;
with ethylene are preferably those which contain poly-merizable unsaturation, such as is present in compounds containing an ethylene linkage, > C - C ~ . These other interpolymerizable compounds may be hydrocarbon com- ~ ~;
pounds such as, butene-l, pentene-l, isoprene, butadiene, `~
bicycloheptene, blcycloheptadiene, and styrene, as well as vinyl compounds such as vinyl acetate and ethyl acrylate. :
These copolymers could thus include those containing `
> 0 to 70 weight percent of propylene and 30 to < 100 weight percent of ethylene; and ~ 0 to ~ 50 weight percent ;
butene-l or vinyl acetate and 50 to C 100 ~eight percent of ethylene; and > 0 to ~ 30 weighk percent of propylene, > 0 to 20 weight percent of butene-l -and 50 to ~ 100 weight percent of ethylene.
The ethylene polymers may be used individ- -ually, or in combinations thereof. The ethylene poly-mers have a density (ASTM 1505 test procedure with conditioning as in ASTM D-1248-72) of about 0.86 to 0.96 and a melt index (ASTM D-1238 at 44 psi test . .
~ ~ 8-.~
~ 5 56 ~ Z 9751 , pressure) of about 0.1 to 20 decigrams per minute.
FIRST PEROXIDE COMPOUND
The first peroxide compound which is employed in the compositions of the present inven~ion ;s employ-ed therein as the primary w lcanizing agent for the ethylene polymers. These compounds are organic per-oxides which have a decomposition half-life of about 0.5 to 4.5 minutes, and preferably of about 1 to 2 minutes, at 160-200C, and preferably at 180-190C, and which have the structure ~ ,CH3 ,CH3 - CH3 ,CH3-R' _ _ C - O - O - C - R- _ C - O ` O - C - .
_ CH3 CH3 _ n CH3 CH3_ wherein R is a C2 to C12 saturated or un-saturated divalent hydrocarbon radical, ~.
R' and R" are the same or different Cl to C12 saturated or unsaturated monovalent hydrocarbon radicals, and n L~ a whole number Qf 0 or 1.
The R radicals would include aromatlc hydro-carbon radicals such as phenylene J and saturated and unsaturated linear C2 to C4 hydrocarbon radicals such as ethynylene (-C-C-) and ethylene (-CH2-CH2-). The .
R, R' and R" radicals may be unsubstituted, preferably, or they may be substituted with inert inorganic radicals such as Cl.
~'',' .
9. : ~
.. .. ;; ~
~5~64~
The preferred of the first peroxide compounds are ~hose wherein R' - R".
When n is 0 the first peroxide compounds would include (with their decomposition half-lie at 180C) di ~ - cumyl peroxide. (0.8 to 1.2 minutes), di -~ , p - cyml peroxide ~ 0.6 ~o 1.0 minu~e-) and di-t-butyl peroxide (3.0 to 3.1 minutes).
When n is 1 the first peroxide compounds would include (with their decomposition half-life at 180C) "-bls (t-butyl peroxy di-lsopropyl)benzene (1.0 to 1.3 mlnutes), 2,5-dimethyl-2,5-di(t-butyl peroxy) hexane (1.2 to 1.4 minutes) and 2,5-dimethyl-2,5-di(t-~utyl peroxy) hexyne-3, (4.2 to 4.4 minutes).
The first peroxides can be used individually or in combination with one another.
SECOND PEROXIDE COMPOUND
The second peroxide compound which is employ-ed in the compositions of the present invention is employed therein primarily to prevent scorching of the composition. It does not participate, to any signifi-cant extent, in the vulcanization of the ethylene poly-mer in the composition. Its mode of ac~ivity in this regard is not entirely understood but it is believed ~ ;
to result from donation of its active hydrogen atom to 10.
. ~ . , : . ~ . : . . .
~ ~ S S~ ~2 9751 the free radical of the first peroxide compound. This rate of donation, ~mder a given set of processing con-ditions, is faster than the rate oE abstraction of free radicals from the ethylene polymer, so that the vulcanizing utility of the first perogide compound is retarded in the presence of the second peroxide compound.
These second peroxide compo~mds are Drganic hydroperoxides which have a decomposition half-life of about 0.5 to 3 hours, and preferably of about l to 2 hours, at > 160 to 200C and preferably at 180-190C, and they have the structure C~13 CH3 H - 0 - 0 - C - - R' or H - 0 - 0 - C R"
wherein R' and R" have the same meaning as disclosed above with respect to the first compounds.
Examples of the second peroxide compounds which may be used in the compositions of the present inventlon, in accordance with the disclosure made above, would include (with their decomposition hal-life at 180C.) ;
Cumene hydroperoxide, (1.3 to 1.5 hours) t-butyl hydroperoxide, ( 3 hours 2,5-dimethyl-2,5-di-hydroperoxy hexane (1.0 to 1.1 hours) The specific second peroxide compound(s) em-ployed in a composition are pre~erably those which ~S564Z
have a decomposition rate which is at least about 20 to 100, and is most preferably about 60 to 80, times slower than the decomposition rate of the first peroxide com- ~ -pound(s) employed in such composition, at the intended ~
vulcanization temperatures. ;
The second peroxides can be used individually or in combination with each other.
A~LYL COMPOUNDS
~ The organic compounds which contain at least three allyl groups which can be used in the present invention include triallyl cyanurate trlallyl phosphate triallyl phosphite triallyl ortho formate, and tetra-allyloxy ethane.
About 0.5 to 3.0 , and preferably about 1 to 2 parts by weight of the allyl compound is used per l to 5 parts by weight o~ the first peroxide. ~ i l~e allyl compounds may be used individually or in combination with each other.
Adjuvants In addition to the ethylene polymer, the two peroxide compounds, and the allyl compounas, the :
12.
. ,; .. . . .
~55642 9751 compositions of the present invention also advantageously include about 0.01 to 3.0 and, preferably 0.05 to 1.0, parts by w~ight of one or more suitable high temperature antioxidants for the ethylene polymers, per lO0 parts by weight of ethylene polymer in such c~mpositions.
These antioxidants are preferably sterically hindered phenols. Such compounds would include 1,3,5-trimethyl-2,4,6-tris(3,5-ditertiary butyl-4-hydroxy benzyl)benzene; 1,3,5-tris(3,5-ditertiary butyl -4-hydroxy benzyl)-5-triazine-2,4,6-(lH,3H,5H~trione;
tetrakis- ~methylene-3-(3',5-di-t-butyl-4'-hydroxy phenyl)-propionate]methane; and di(2-methyl-4-hydroxy-5-t-butyl phenyl)suLfide. Polymerized 2,2,4-trimethyl dihydroquinoline may also be used.
Other adjuvants which may be employed in the compositions of the present invention would include adjuvants commonly employed in vulcanizable ethylene polymer based compositions including fillers, such as carbon black, clay, talc and calcium carbonate; blowing agents; nucleating agents for blown systems;
lubricants; W stabilizers; dyes and colorants; voltage stabilizers; metal deactivators and coupling agents.
~ hese adjuvants would be used in amounts de~
signed to provide the intended e~fect in the resulting composition.
The compositions of the present invention may also be extended, or filled, with polymers other 13.
~ S S6 ~2 9751 than the ethylene polymer which are compatible, i.e., ;~
can be physically blended or alloyed, with the ethylene polymer. The resulting compositions should contain at least about 30 weight percent of interpolymerized ethylene in all the polymers that may be present in the composition, based on the total weight of the resulting composition. The other polymers which may be used would include polyvinyl chloride and polypropylene.
The total amount of adjuvants used will range from 0 to about 60 weight percent based on the total weight of the composition.
Processing o~ the_Compositions All o~ the components o~ the compositions of the present invention are usually blended or compounded together prior to their introduction into the extrusion device ~rom which they are to be extruded onto an electri-cal conductor. The ethylene polymer and the other desired constituents may be blended together by any o~
the techniques used in the art to blend and compound thermoplastics to homogeneous masses. For instance, the components may be fluxed on a variety o~ apparatus including multi-roll mills, screw mills, continuous mixers, compounding extruders and Banbury mixers, or dissolved in mutual or compatible solvents.
14.
~, ~ r When all the solid components of th~ composi-tion are available in the form of a powder, or as small particles, the compositions are most conveniently pre- i pared by first making a blend of the components, say in a Banbury mixer or a continuous extruder, and then masticating this blend on a heated mill, ~or instance a two-roll mill, and the milling continued until an intimate mixture of the components is obtained.
Alternatively, a master batch containing the ethylene polymer(s) and the antioxidants(s) and, if desired, some or all of the other cumponents~ may be addecl to the mass of polymer. Where the ethylene polymer is not available in powder form, the compositions may be made -by intrDducing the polymer to the mill, masticating it ~`
until it forms a band around one roll, after which a blend of the remaining components is added and the milling continued until an intimate mixture is obtained.
l'he rolls are preferably maintained at a temperature which is within the range 80C to 150C. and which is ~ ~;
below the decomposition temperatures of the first per- `
oxide compound(s). The composition, in the form of a sheet, is removecl from the mill and then brought into `
a form, typically dice-like pieces, suitable for sub-sequent processing.
~VS5S,4;~
~ fter the various components of the compositions of the present inventlon are uniformly admixed and blended together, they are further processed, in accordance with the process of the present invention, in conventional extrusion apparatus at about 1~0 to 160~C.
After being extruded onto a wire or cable, or other substrate, the compositions of the present invention are vulcanized at elevated temperatures of about ~ 180C.
and preferably at > 215-230C. using conventional vulcanizing procedures.
Deriv?tion of Curing System Efficiency Factor In the Monsanto Rheometer Test Procedure a sample of the v~llcanizable composition is measurecl in a rheometer before the composition is subject to high temperature mixing or extrusion conditions. The test results are plotted as functions of inch-pounds of torque versus time. ~ The compositions which are less susceptible to scorching are those that experience, aE~er the minimum torque value is achieved, a delay in the rise of the torque values Eollowed by a fast rise in the torque values to the level required for the in-tended end use of the composition being evaluated.
The Monsanto ~heometer Test Procedure is, in effect, a means for c~nparitively evaluating, graphically, the susceptibility of different vulcanizable compositions to scorch~ In this wa~ the use o-f different cu~ing agents, or curing agent compositions, in such vulcanizable com~-positions, can also be graphically cc~pared.
16.
.: , , ., ~ . :-, ~ 5 56 ~Z 9751 For the purposes of the present invention, a procedure has now been devised whereby, using the graphical results of Monsanto Rheometer Test procedures, the efficiency of different curable compositions, relative to the susceptibility of such compos:itions to scorching, can also be numerically compared. By using this new evaluation procedure, a separate and distinct numerical-efficiency factor (E) can be assigned to each curable composition. To make these efficiency factors more meaningful, for comparison purposes, they should be based on rheometer curves which are all obtained when the curable compositions beingcompared are evaluated under the same test conditions. In all the experi~ents reported herein the test samples were evaluated in a Monsanto Rheometer at a cure temperature of 360F., using a rhebmeter oscillation of 110 CPM and an arc of + 5.
There is also provided here below, the derivation of a numerical efficiency factor (E) for vulcanizable compositions . The derivation employs typical rheometer curves that were arbitrarily drawn, and which are not based on actual experiments. Such curves are shown in Figures 1 and 2 of the drawings.
A typical Monsanto ~heometer curve~ as shown graphically in Figure 1, contains several parameters which `~
are used in the derivation of the efficiency factor (E).
The optimum cure level ~highest cross link density)is ... .
17. ~
". ~.
:,. .. .
55q;4;~ , designated as H. H is measured in terms of inch-pounds of torque on the rheometer test equipment. A higher value for H corresponds to a higher cross-link density.
The time, in minutes, required to reach 90% of the maximum cure (H) is designated as CT. Thus, ~n Yigure 1, H is 50 inch-pbunds and CT is 5.5 minutes, which is the time required to reach a level of 45 (or 90% of 50) inch-pounds of torque during the test procedure.
The scorch time, ST, is defined as the point in , time, in minutes, at which the curve reaches a rhe~meter level of 10 inch-pounds of torque on the upswing of the curve. In Figure 1, ST is about 2.1 minutes.
In general, one is interested in getting to the maximum cure ~H) as soon as possible. In other worcls, a short CT is desirable. At the same time, one would like ST to be as long as posslble since a longer ST means the vulcanizable composition being evaluated can be processed at a higher speed or at a higher temperature.
That is, it would be less scorchy. Thus it is important to discuss the time intervals between CT and ST, or CT ~ ST since CT is, arbitrarlly, always longer than ST.
Then, too, it is of interest to compare ST with CT ~ ST since the best vulcaniæable system would be one whose ST is relatively long, and whose difference between CT and ST, (CT - ST), would be relatively short. Thus, the ratio ST/CT - ST is of importance. The larger is this 18.
5 5~ ~
ratio, the less susceptible is the vulcanizable composition to scorching.
Finally, the times (CT and ST) are related to the maximum cure point H. Thus, if one can maintain the same ST, and yet reach a higher H, one can thereby -~
provide a vulcanizable composition that is less : :.
susceptible toscorch. When vulcanizable compositions ~.
are cured by peroxide curing agent systems, particularly those using individual peroxides such as dicumyl peroxide, as you increase the value of H, by simply adding more oE the peroxide curin~ agent, you decrease ST. :
The efficiency of a particular curing agent system, therefore, when used with a given vulcanizable composit.ion, and cured at a given temperature, can be determined by multiplying H by ST / CT - ST or, as shown in Equation I; ~ `
T (I) CT T .
The numerical ef~ic:lency (E) of the arbitrary curing agent system shown graphically in Figure 1 there~ore, would, be E = H x ST = (50) (2.l) = 30.9 ~ 5.5 - 2.1 .
To further illustrate the utility of this method, for the purposes of comparitively evaluating different :
vulcanizable composîtions, reference is made to Figure 2 of the drawings in which there is graphically presented typical Monsanto Rheometer curves 1 and 2 that were also -19 .
, f `~
~5564~ 9751 arbitrarily drawn, and which are not based on actual ~ -experiments.
It should be noted from a review of Figure 2 that the cure times CT 1 ~or composition 1 and CT 2 for composition 2, are the same for both compositions and each curve reaches a relatively high torque level with the value of Hl (for composition 1) which is 70, being relatively close to the value of H2 (for composition 2) which is 62. ST 2 (for composition 2), however, is more than a mlnute longer than ST 1 (for composition 1), 3.2 vs 2.0 minutes. Thus, i~ is qulte obvious from a review of these two curves that curve 2 represents the better cure system. If one maintains the same CT, and reaches almost the same maximum cross-link density (H), `
then increasing ST must lead to a better curing system, in accordance with the above definition of E.
A calculation of the relative numerical effi-ciencies of the curable compositions shown graphically in Figure 2 is shown below:
Efficiency (El) of composition 1, based on curve l:
El Hl x STl = (70) (2) = 140 = 35.0 CTl ~ STl ( 6 - 2) 4 Efficiency (E2) of composition 2, based on curve 2:
E2 = H2 x ST2= (62) (3.2)= 198.4 = 70.8 CT2 ~ ST2(6 - 3.2) 2.8 20.
- .:
. .
.. . . .
. ; ~ .. . . . . .
~S564Z 9751 , ", ' Thus, this efficiency factor, E, is a useful parameter and it can be shown that in fact a higher value for E represen~s a better system, as defined above, and represents improved utility for such better system. The use of this efficiency factor, E, can also apply to comparisons of Rheometer test curves where the maximum cure (H) shown in each curve is vastly different, since the calculation of E is, in effect, a normalization procedure.
The compositions of the present invention have an efficiency factor (E),as determined above, which is at least about 3, and is preferably more than 10 to 15, units of such efEiciency factor above the eEficiency factor o~ such compositions in the absence of the allyl compounds.
The Eollowing examples are merely illustrative of the present invention and are not intended as a limit-ation upon the scope thereof.
General Admixing Procedure The vulcanizable compositions used in Examples 1-36 were all prepared by the following procedure:
100 parts by weight of the ethylene polymer were fluxed in a Banbury mixer at approximately 120C. The additives, i.e., anti-oxidant, and the first and second -peroxides and the allyl compounds, and, where used, other adjuvants, were then added to the fluxed mixture. The resulting composition was then blended for 2-3 minutes and then transferred to a 2-roll mill for sheeting. The hot rolled sheet was then chopped on a hot granulator to yield a chipped product.
21.
, ... .. .
97,~ :
~ S 56 ~
The chips were then compression molded in~o plaques for use in Monsanto Rheometer test procedures.
~11 of the rheometer data which was then obtained on ~he samples, unless otherwise stipulated, was obtained at 360~F. (182.2~C.).
Examples 1-5 Five vulcanizable compositions were prepared as in the General Admixing Procedure utilizing dicumyl peroxide (DCP) as a first peroxide compound with a low density (density of < 0.94) ethylene homopolymer .
- Homopolymer I - ~having a density of 0.919, a melt ~ ~ .
index of 1.6 - 2.2 ~lP, 190C.], cumene hydroperoxide ;
(Cumene ll) as a second peroxide compound and trial.lyl cyanurate (TAC). The compositions are shown, in parts by weight in Table I.
TABLE I
Exampl~s 1 _ 3 4 5 -Homopolymer I 100.0 100.0 100.0 100.0 100.0 DCP 2.0 2.0 1.0 2.0 2.0 TAC - 0.5 l.0 0.5 - ..
Cumene H. - - - 0.5 0.
When tested for Efficiency Factors, as disclose~
above, the compositions of Examples 1-5 had Efficiency Factors, based on the values for H, CT and ST, as disclosed below in Table II.
22.
~ . .
-~ 97 1 TABLE II
Examples 1 2 3 4 5 H 44.0 64.0 44.0 54.024.0 T 5.5 5.0 5.6 4.65.6 ST 1.75 1.5 2.1 1.82.8 E 20.5 27.4 26.4 34.724.1 These results indicate that although the use of TAC or Cumene H alone (Examples 2, 3 & 5) wil] increase the E value of the composition of Example 1, the use of TAC
plus Cumene H provides a much higher E value (Example 4) than would be expected based on the results of Examples 2, 3 and 5.
Examples 6-9 Four vulcanizable compositions were prepared as in Examples 1-5 using ethylene homopolymer I? TAC, Cumene H, and 2,5-dimethyl-2,5-di-tertiary butyl peroxy hexane (2,5-DTBPH) as a first peroxide compound. The compositions are shown, in parts by weight, in Table III.
TABLE III
Examples 6 7 8 9 Homopolymer I 100.0100.0 100.0 100.0 2,5-DTBPH 2.01.0 2.0 1.0 rA~ - 1 .0 - 1 . O
Cumene H - - 0.5 0.5 ," ,. .
23.
~ 5S~4Z
When tested for Efficienc~- Factors, as disclosed above, the Compositions of Examples 6-9 had Efflciency Factors, based on the values of H, CT and ST, as disclosed below in Table IV
TABLE IV .
Examples 6 7 8 9 H 50.0 52.0 32.0 45.0 CT 10.2 9.0 11.0 10.7 ST 2.4 2.8 3.7 4.3 : ; .
E 15.8 23.5 16.2 30.3 These results indicate that although the use of TAC or Cumene H alone (Examples 7-8) wil:L increase the E
value of the composition of Example 6 somewhat, the use oE TAC plus Cumene H provides a much higher E value (Example 9) than would be expected based on the results of Examples 7 and 8.
Examples 10-13 Four vulcanizable compositions were prepared as in Examples 1-5 utilizing homopolymer I, TAC, Cumene H, and ~ , n -bis (tertiary butyl peroxy) cli-isopropyl ben2ene (TBPDIP) as a first peroxide compound. The compositions are shown, in parts by weight, in Table V.
TABLE V
Examples 10 11 12 13 Homopolymer I 100.0 100.0100.0 100.0 TBPDIB 2.0 2.0 1.0 1.0 ~AC - - 1 . O :L . O ,~
Cumene H - 0.5 - 0.5 24.
- ` 9 75 l¢:lSS642 When tested for E:Eficiency Factors, as disclosed ;`
above, the Compositions of Examr,les 10-13 had Efficiency Factors, based on the values for H, CT and ST, as disclosed below in Table VI. ~ .
TABLE VI
Examples 10 11 12 13 H 70.0 63.0 68.062.0 CT 8.7 8.4 7.3 7.2 . .
5T 1.6 2.4 1.3 2.2 E 15.8 25.1 14.127.3 :
These results indicate that since the use of ~AC
alone ~Example 12) decreases the E value of the composition o~ E~ample 10, that the use o TAC plus Cumene H pro~ides a higher E value (Example 13) than would be expected, notwithstanding the increased value of E that might be expected from using Cumene H (Example 11) above. ::
Examples 14-17 Four vulcanizable composi-tions were prepared as in Examples 1-5 utilizing DCP as the first peroxide, TAC, tertiary butyl hydroperoxide (TBH) as the second peroxide, and an ethylene-ethyl acrylate copolymer (copolymer I) which contained 15% by weight o~ ethyl acrylate and had a melt index of 1.6 - 2.2 (lP, 190C). The compositions are shown, in parts by weight, in Table VII.
TABLE VII
Examples 14 15 16 17 :
_ Copolymer I 100.0 100.0 100.0100.0 :.
DCP 2.0 2.0 1.01.0 .
TAC - - l.0l.0 .
TBH - 0.2 - 0.2 25.
.. . , : -~ S 5~ ~2 9751 When tested for Efficiency Factors, as disclosed ~: .
above, the compositions of Examples 14-17 had Efficiency Factors, based on the values of H, CT and ST, as disclosed below in Table VIII
TABLE VIII
Examples 14 15 16 17 H 67.0 44.0 76.0 72.0 C 5.3 5.6 4.9 5.5 T
ST 1.1 2.1 1.13 1.9 E 16.9 25.8 22.9 38.0 These results indicate that although the US2 of TAC or TBH alone (Examples 15-16) will incre~se the E value oE the composition of Example l4, the use of T~C plus TBH
provides a much higher E value (Example 17) than would be expected based on the results of Examples 15-16.
Examples 18-21 Four w lcanizable compositions were prepared as in Examples 1-5 utilizing DCP as the -first peroxide, TAC, TBH as the second peroxide, and an ethylene-vinyl acetate copolymer (Copolymer II) which containecl 10%
by weight of vinyl acetate and had a melt index of 2.0 (lP, 190C). The compositions are shown, in parts by weight, in Table IX.
IA~LE IX
Examples 18 19 20 21 Copolymer II 100.0 100.0 100.0 100.0 DCP 2.0 2.0 1.0 1.0 TAC - - 1.0 1.0 T~l - 0.2 - 0.2 26. ~ t '". ':' ' '' '': ' :
~ ~ 5 ~6~ 9751 ~.
When tested for Efficiency Factors, as disclosed -above, the compositions of Examples 18-21 had Efficiency Factors, based on the values of H, CT and ST, as disclosed below in Table X.
T~BLE X
.
Examples 18 19 20 21 H 73.0 62.0 74.0 79.5 .. ..
CT 4.8 5.2 3.9 4.1 ST 1.05 1.85 1.05 1.7 ~
E 20.4 34.2 27.3 55.2 .
These results indicate that although the use of rrAc or TBH alone (Examples 19-20) will increase the E
value of the composition of Example 18, the use of ~.~C
plus TBH provides a much higher E value (Example 21) `
than would be expected based on the results of Examples 19-20.
Examples 22-25 Four vulcanizable compositions were prepared ..
as in Exa~ples 1-5 utili~ing c~ ' -bis (tertiary-butyl peroxy diisopropyl)benzene(TBPDIP) as the first peroxide, TAC, TB~ and three ethylene polymers. The three polymers were ;~
a high density ( > 0.94) ethylene homopolymer (Homopolymer II) .~:
having a density of 0.96 and a melt index of 8.0 (lP, 190C); ~.
an ethylene-ethyl acryla~e copolymer (Copolymer III) having .
an ethyl acrylate content of 23 weight percent, a density of 0.92 and a melt index of 20 (lP, 190C); and an :
ethylene-ethyl acrylate copolymer (Copolymer IV) having 27.
~SS64Z
an ethyl acrylate content of 18 percent by weight and a melt index of 4.5 ~lP, 190C). Homopolymer II
and Copolymer III were added to the composition as is. Copolymer IV was added to the composition in the form of Formulation I which contained 68 percent by weight of Copolymer IV and 32% by weight of carbon black.
The compositions are shown, in parts by weight, in ;
Table XI.
TABLE XI
Exam~ 22 23 24 25 Homopolymer II10.0 10.0 10.0 10.0 Copolymer III45.0 45.0 45.0 45.0 Formulation I45.0 45.0 45.0 45.0 TBPDIP 1.75 0.8 0.7 0.7 IAC - 0.8 0.7 0.7 TB~ - - - 0.2 When tested for Efficiency Factors, as disclosed above, the compositions of Examples 22-25 had Efficiency Factors, based on the values for H, CT and ST, as 20 disclosed below in Table XII.
TABLE XII
Examples 22 23 24 25 H 100.0 77.0 63.0 71.0 CT 9.0 . 6.9 7.2 7.7 ST 1.7 1.6 2.0 2.5 -E 23.3 23.3 24.2 34.2 28.
' ,' ~, 9751 ' ~qgS5~ 2 These results indicate that although the use of T~C or TBH alone (Examples 23-24) provides little or . .
no increase in the E value of the composition of ~: .
Example 22, the use of ~AC plus TBH provides a substantial ..
increase in the E value (Example 25) of the composition .
of Example 22.
29.
1~556~ 9751 Examples 26-31 Six carbon black filled, vulcanizable compositions were prepared as in Examples 1-5 utilizing dicumyl peroxide (DCP) as the first peroxide, TBH, various unsaturated allyl or acrylate compounds and Copolymer ~lo The compositions contained, as an antioxidantJ polymerl7ed 2~2,4-trimethyl-di-hydroquinoline. The compositions are shown, in parts by weight, in Table XIII.
Table XIII
Examples 26 27 28 29 30 3L
Copolymer II 73.8 73.8 73.8 73.8 73.8 73.8 Carbon black 25.8 25.8 25.8 25.8 25.8 25.8 Antioxidant 0.4 0.4 0.4 0.4 0.4 0.4 DCP 1.6 0.8 0 8 0.8 0.8 0.8 T~H - - 0.2 0.2 0.2 0.2 TAC - 0.8 0.8 - - -TAP - - - 0.7 TMPTM - - - - 1.09 - .
TMPTA ~ O.96 TAP - triallyl phosphate TMPTM = trimethylol propane trimethacrylate TMPTA = trimethylol propane triacrylate Wben tested for Efficiency Factors, as disclo~ed above, the composition of Examples 26-31 had Efficiency Factors, ba~ed on the values of H, CT and ST, as disclosed be:Low in Table XIV.
30.
.. . . . ; . .. ., :
TABLE XIV
Examples 26 27 28 29 30 31 H 83.0 80.0 87.0 74.0 48.040.0 CT 4.2 3.5 4.0 4.0 4.74.1 ST 0.92 1.03 1.4 1.38 1.5 1.1 E 23.3 33.4 46.8 39.0 22.5 18.3 These test results indicate that although the use ;
of TAC alone (Example 27) will improve the E value of the composition of Example 26, the use of TBH plus TAC, or TAP, will further substantially increase the E value of the `
composition of Example 26 over that obtained by the use of TAC alone. Further, the use of the triflmctional acrylate compounds TMPTM and TMPTA has a detrimental efect on the E value o the composition of Example 26, in the presence of TBH.
. ~ . .
Examples 32-36 Five vulcanizable compositions were prepared as in Examples 1-5 utilizing DCP, as the first paroxide, TAC, TBH or cumene hydroperoxide (Cumene H) as the second 20 peroxide, and Homopolymer I. The compositions contained, as an antioxidant, bis(2-methyl-4-hydroxy-5-t-butyl phenyl) sulfide. The compositions are shown, in parts by weight, in Table XV.
. . . .
~,........ .. ~ . . . , : . ... . . .
~055642 , TABLE XV
Examples 32 33 34 35 36 Homopolymer I 100.0 100.0 100.0 100.0 100.0 Antioxidant 0.2 0.2 0.2 0.2 0.2 DCP 2.0 1.0 1.0 2.0 2.0 TAC - 1.0 1.0 0.5 0.5 TBH - - 0.2 - -C~nene H - - - - O,5 When tested for Efficiency Factors, as disclosed 10 above, the compositions of Examples 32-36 had Efficiency Factors, hased on the values of H, CT and ST, as disclosed below in Table XVI.
TABLE XVI
Examples 32 33 34 35 36 H 42.7 48.5 46.0 63.3 49.5 CT 4.7 4.8 5.2 4.2 4.7 ST 1.7 1.9 2.46 1.42 2.15 E 24.2 31.8 41.3 32.3 41.7 These test results indicate that although the 20 use of TAC alone (Examples 33 and 35) will improve the E value o~ the composition of Example 32, the use of .
TBH or Cumene H plus TAC (Examples 34 and 36) will further substantially increase the E value of the composition of Example 32 over that obtained by ~he use of TAC alone.
In all cases the tertiary butyl hydroperoxide was used in the form of a mixture of 90% tertiary butyl hydroperoxide and 10% tertiary butyl alcohol.
32. `;
Summary o~ the Invention It has now ~een found that vulcanizable ethylene polymer based compositions which employ certain classes. of organic peroxides therein as vulcanizing .
agents, and which compositions are susceptible to scorching under a given set of conditions, can ~e pro-tected against scorching under such conditi~ns by in-corporating in such compositions certain classes of organic hydroperoxides and organic compounds containing at least three allyl groups.
An object o~ the present invention is to pro-vide scorch resistant, w lcanizable, ethylene polymer based compositions.
Another object of the present invention is ~o provide a process for protecting against scorching vulcanizable ethylene polymer based compositions which employ therein certain classes of organic peroxides as ~5564~ 9751 vulcanizing agents and which are susceptible to scorch-ing.
A further object of the present invention is to provide scorch resistant insulation for electrical wire and cable.
A further object of the present invention is to provide a process whereby vulcanizable ethylene polymer based compositions which employ therein certain classes o~ organic peroxide compounds as vulcanizing agents and which compositions are susceptible to scorch^ `
. .
ing, may be processed in mixing and extruding devices, prior to the vulcanization thereof, at fast throughput rates and at relatively high processing temperatures without experiencing scorching.
These and other objects of the present invention are achieved by employing certain classes of organic~ :
hydroperoxides in combination with organic compounds containing at least three allyl groups as scorch preventing agents in the compositions of the present inventions.
rHE DRAWINGS
Figures 1 and 2 of the drawings show, graphically, Monsanto Rheometer Test curves which were used to illustrate the derivation of an efficiency factbr as described below.
6.
... . .. .. . , ,~ .
. . . . . ' , : , . . . .
, ` ~ S 5~ 42 DESCRIPTION OF THE PREFERRED EMBODIMENT
The Scorch Resistant Composition The scorch resistant compositions of the present invention comprise, in wei.ght ratio, lOQ parts by weight of ethylene polymer, about 0.1 to 5 0, and preferably 0.2 to 2.0, parts by weight of at least one first peroxide compound which has carbon atoms directly bonded to each oxygen atom of each peroxide group (-o-o-) therein, and which compounds, as a class, are described below, about 0.1 to 2.0, and preferably about 0.05 to 1.0, parts by weight of at least one second peroxide compound which i8 a hydroperoxide of the class described below, and about 0.1 to 5.0, and preferably about 0.2 to 2.0 parts by weight of one or more organic compounds containing at least three allyl groups.
About one part by weight of the second peroxide is used per 2 to 10 parts by weight of the first peroxide.
About one part by weight of the allyl compound is used per 1 to 5 parts by weight of the first peroxide .
Ethylene Polymer The ethylene polymers which are used in the compositions of the present invention are solid (at 7.
l B
. . .; . , " i., ..` . .,. ~;" ,~
5 ~ 4~ 9751 ~' , 25C.) materials which may be homopolymers, or copoly-mers of ethylene. The ethylene copolymers contain at least 30 weight percent of ethylene and up to about 70 weight percent of propylene, and/or up to about 50 weight percent of one or more other organic compounds which are interpolymerizable with ethylene.
:; . . .
These other compounds which are interpolymerizable ;
with ethylene are preferably those which contain poly-merizable unsaturation, such as is present in compounds containing an ethylene linkage, > C - C ~ . These other interpolymerizable compounds may be hydrocarbon com- ~ ~;
pounds such as, butene-l, pentene-l, isoprene, butadiene, `~
bicycloheptene, blcycloheptadiene, and styrene, as well as vinyl compounds such as vinyl acetate and ethyl acrylate. :
These copolymers could thus include those containing `
> 0 to 70 weight percent of propylene and 30 to < 100 weight percent of ethylene; and ~ 0 to ~ 50 weight percent ;
butene-l or vinyl acetate and 50 to C 100 ~eight percent of ethylene; and > 0 to ~ 30 weighk percent of propylene, > 0 to 20 weight percent of butene-l -and 50 to ~ 100 weight percent of ethylene.
The ethylene polymers may be used individ- -ually, or in combinations thereof. The ethylene poly-mers have a density (ASTM 1505 test procedure with conditioning as in ASTM D-1248-72) of about 0.86 to 0.96 and a melt index (ASTM D-1238 at 44 psi test . .
~ ~ 8-.~
~ 5 56 ~ Z 9751 , pressure) of about 0.1 to 20 decigrams per minute.
FIRST PEROXIDE COMPOUND
The first peroxide compound which is employed in the compositions of the present inven~ion ;s employ-ed therein as the primary w lcanizing agent for the ethylene polymers. These compounds are organic per-oxides which have a decomposition half-life of about 0.5 to 4.5 minutes, and preferably of about 1 to 2 minutes, at 160-200C, and preferably at 180-190C, and which have the structure ~ ,CH3 ,CH3 - CH3 ,CH3-R' _ _ C - O - O - C - R- _ C - O ` O - C - .
_ CH3 CH3 _ n CH3 CH3_ wherein R is a C2 to C12 saturated or un-saturated divalent hydrocarbon radical, ~.
R' and R" are the same or different Cl to C12 saturated or unsaturated monovalent hydrocarbon radicals, and n L~ a whole number Qf 0 or 1.
The R radicals would include aromatlc hydro-carbon radicals such as phenylene J and saturated and unsaturated linear C2 to C4 hydrocarbon radicals such as ethynylene (-C-C-) and ethylene (-CH2-CH2-). The .
R, R' and R" radicals may be unsubstituted, preferably, or they may be substituted with inert inorganic radicals such as Cl.
~'',' .
9. : ~
.. .. ;; ~
~5~64~
The preferred of the first peroxide compounds are ~hose wherein R' - R".
When n is 0 the first peroxide compounds would include (with their decomposition half-lie at 180C) di ~ - cumyl peroxide. (0.8 to 1.2 minutes), di -~ , p - cyml peroxide ~ 0.6 ~o 1.0 minu~e-) and di-t-butyl peroxide (3.0 to 3.1 minutes).
When n is 1 the first peroxide compounds would include (with their decomposition half-life at 180C) "-bls (t-butyl peroxy di-lsopropyl)benzene (1.0 to 1.3 mlnutes), 2,5-dimethyl-2,5-di(t-butyl peroxy) hexane (1.2 to 1.4 minutes) and 2,5-dimethyl-2,5-di(t-~utyl peroxy) hexyne-3, (4.2 to 4.4 minutes).
The first peroxides can be used individually or in combination with one another.
SECOND PEROXIDE COMPOUND
The second peroxide compound which is employ-ed in the compositions of the present invention is employed therein primarily to prevent scorching of the composition. It does not participate, to any signifi-cant extent, in the vulcanization of the ethylene poly-mer in the composition. Its mode of ac~ivity in this regard is not entirely understood but it is believed ~ ;
to result from donation of its active hydrogen atom to 10.
. ~ . , : . ~ . : . . .
~ ~ S S~ ~2 9751 the free radical of the first peroxide compound. This rate of donation, ~mder a given set of processing con-ditions, is faster than the rate oE abstraction of free radicals from the ethylene polymer, so that the vulcanizing utility of the first perogide compound is retarded in the presence of the second peroxide compound.
These second peroxide compo~mds are Drganic hydroperoxides which have a decomposition half-life of about 0.5 to 3 hours, and preferably of about l to 2 hours, at > 160 to 200C and preferably at 180-190C, and they have the structure C~13 CH3 H - 0 - 0 - C - - R' or H - 0 - 0 - C R"
wherein R' and R" have the same meaning as disclosed above with respect to the first compounds.
Examples of the second peroxide compounds which may be used in the compositions of the present inventlon, in accordance with the disclosure made above, would include (with their decomposition hal-life at 180C.) ;
Cumene hydroperoxide, (1.3 to 1.5 hours) t-butyl hydroperoxide, ( 3 hours 2,5-dimethyl-2,5-di-hydroperoxy hexane (1.0 to 1.1 hours) The specific second peroxide compound(s) em-ployed in a composition are pre~erably those which ~S564Z
have a decomposition rate which is at least about 20 to 100, and is most preferably about 60 to 80, times slower than the decomposition rate of the first peroxide com- ~ -pound(s) employed in such composition, at the intended ~
vulcanization temperatures. ;
The second peroxides can be used individually or in combination with each other.
A~LYL COMPOUNDS
~ The organic compounds which contain at least three allyl groups which can be used in the present invention include triallyl cyanurate trlallyl phosphate triallyl phosphite triallyl ortho formate, and tetra-allyloxy ethane.
About 0.5 to 3.0 , and preferably about 1 to 2 parts by weight of the allyl compound is used per l to 5 parts by weight o~ the first peroxide. ~ i l~e allyl compounds may be used individually or in combination with each other.
Adjuvants In addition to the ethylene polymer, the two peroxide compounds, and the allyl compounas, the :
12.
. ,; .. . . .
~55642 9751 compositions of the present invention also advantageously include about 0.01 to 3.0 and, preferably 0.05 to 1.0, parts by w~ight of one or more suitable high temperature antioxidants for the ethylene polymers, per lO0 parts by weight of ethylene polymer in such c~mpositions.
These antioxidants are preferably sterically hindered phenols. Such compounds would include 1,3,5-trimethyl-2,4,6-tris(3,5-ditertiary butyl-4-hydroxy benzyl)benzene; 1,3,5-tris(3,5-ditertiary butyl -4-hydroxy benzyl)-5-triazine-2,4,6-(lH,3H,5H~trione;
tetrakis- ~methylene-3-(3',5-di-t-butyl-4'-hydroxy phenyl)-propionate]methane; and di(2-methyl-4-hydroxy-5-t-butyl phenyl)suLfide. Polymerized 2,2,4-trimethyl dihydroquinoline may also be used.
Other adjuvants which may be employed in the compositions of the present invention would include adjuvants commonly employed in vulcanizable ethylene polymer based compositions including fillers, such as carbon black, clay, talc and calcium carbonate; blowing agents; nucleating agents for blown systems;
lubricants; W stabilizers; dyes and colorants; voltage stabilizers; metal deactivators and coupling agents.
~ hese adjuvants would be used in amounts de~
signed to provide the intended e~fect in the resulting composition.
The compositions of the present invention may also be extended, or filled, with polymers other 13.
~ S S6 ~2 9751 than the ethylene polymer which are compatible, i.e., ;~
can be physically blended or alloyed, with the ethylene polymer. The resulting compositions should contain at least about 30 weight percent of interpolymerized ethylene in all the polymers that may be present in the composition, based on the total weight of the resulting composition. The other polymers which may be used would include polyvinyl chloride and polypropylene.
The total amount of adjuvants used will range from 0 to about 60 weight percent based on the total weight of the composition.
Processing o~ the_Compositions All o~ the components o~ the compositions of the present invention are usually blended or compounded together prior to their introduction into the extrusion device ~rom which they are to be extruded onto an electri-cal conductor. The ethylene polymer and the other desired constituents may be blended together by any o~
the techniques used in the art to blend and compound thermoplastics to homogeneous masses. For instance, the components may be fluxed on a variety o~ apparatus including multi-roll mills, screw mills, continuous mixers, compounding extruders and Banbury mixers, or dissolved in mutual or compatible solvents.
14.
~, ~ r When all the solid components of th~ composi-tion are available in the form of a powder, or as small particles, the compositions are most conveniently pre- i pared by first making a blend of the components, say in a Banbury mixer or a continuous extruder, and then masticating this blend on a heated mill, ~or instance a two-roll mill, and the milling continued until an intimate mixture of the components is obtained.
Alternatively, a master batch containing the ethylene polymer(s) and the antioxidants(s) and, if desired, some or all of the other cumponents~ may be addecl to the mass of polymer. Where the ethylene polymer is not available in powder form, the compositions may be made -by intrDducing the polymer to the mill, masticating it ~`
until it forms a band around one roll, after which a blend of the remaining components is added and the milling continued until an intimate mixture is obtained.
l'he rolls are preferably maintained at a temperature which is within the range 80C to 150C. and which is ~ ~;
below the decomposition temperatures of the first per- `
oxide compound(s). The composition, in the form of a sheet, is removecl from the mill and then brought into `
a form, typically dice-like pieces, suitable for sub-sequent processing.
~VS5S,4;~
~ fter the various components of the compositions of the present inventlon are uniformly admixed and blended together, they are further processed, in accordance with the process of the present invention, in conventional extrusion apparatus at about 1~0 to 160~C.
After being extruded onto a wire or cable, or other substrate, the compositions of the present invention are vulcanized at elevated temperatures of about ~ 180C.
and preferably at > 215-230C. using conventional vulcanizing procedures.
Deriv?tion of Curing System Efficiency Factor In the Monsanto Rheometer Test Procedure a sample of the v~llcanizable composition is measurecl in a rheometer before the composition is subject to high temperature mixing or extrusion conditions. The test results are plotted as functions of inch-pounds of torque versus time. ~ The compositions which are less susceptible to scorching are those that experience, aE~er the minimum torque value is achieved, a delay in the rise of the torque values Eollowed by a fast rise in the torque values to the level required for the in-tended end use of the composition being evaluated.
The Monsanto ~heometer Test Procedure is, in effect, a means for c~nparitively evaluating, graphically, the susceptibility of different vulcanizable compositions to scorch~ In this wa~ the use o-f different cu~ing agents, or curing agent compositions, in such vulcanizable com~-positions, can also be graphically cc~pared.
16.
.: , , ., ~ . :-, ~ 5 56 ~Z 9751 For the purposes of the present invention, a procedure has now been devised whereby, using the graphical results of Monsanto Rheometer Test procedures, the efficiency of different curable compositions, relative to the susceptibility of such compos:itions to scorching, can also be numerically compared. By using this new evaluation procedure, a separate and distinct numerical-efficiency factor (E) can be assigned to each curable composition. To make these efficiency factors more meaningful, for comparison purposes, they should be based on rheometer curves which are all obtained when the curable compositions beingcompared are evaluated under the same test conditions. In all the experi~ents reported herein the test samples were evaluated in a Monsanto Rheometer at a cure temperature of 360F., using a rhebmeter oscillation of 110 CPM and an arc of + 5.
There is also provided here below, the derivation of a numerical efficiency factor (E) for vulcanizable compositions . The derivation employs typical rheometer curves that were arbitrarily drawn, and which are not based on actual experiments. Such curves are shown in Figures 1 and 2 of the drawings.
A typical Monsanto ~heometer curve~ as shown graphically in Figure 1, contains several parameters which `~
are used in the derivation of the efficiency factor (E).
The optimum cure level ~highest cross link density)is ... .
17. ~
". ~.
:,. .. .
55q;4;~ , designated as H. H is measured in terms of inch-pounds of torque on the rheometer test equipment. A higher value for H corresponds to a higher cross-link density.
The time, in minutes, required to reach 90% of the maximum cure (H) is designated as CT. Thus, ~n Yigure 1, H is 50 inch-pbunds and CT is 5.5 minutes, which is the time required to reach a level of 45 (or 90% of 50) inch-pounds of torque during the test procedure.
The scorch time, ST, is defined as the point in , time, in minutes, at which the curve reaches a rhe~meter level of 10 inch-pounds of torque on the upswing of the curve. In Figure 1, ST is about 2.1 minutes.
In general, one is interested in getting to the maximum cure ~H) as soon as possible. In other worcls, a short CT is desirable. At the same time, one would like ST to be as long as posslble since a longer ST means the vulcanizable composition being evaluated can be processed at a higher speed or at a higher temperature.
That is, it would be less scorchy. Thus it is important to discuss the time intervals between CT and ST, or CT ~ ST since CT is, arbitrarlly, always longer than ST.
Then, too, it is of interest to compare ST with CT ~ ST since the best vulcaniæable system would be one whose ST is relatively long, and whose difference between CT and ST, (CT - ST), would be relatively short. Thus, the ratio ST/CT - ST is of importance. The larger is this 18.
5 5~ ~
ratio, the less susceptible is the vulcanizable composition to scorching.
Finally, the times (CT and ST) are related to the maximum cure point H. Thus, if one can maintain the same ST, and yet reach a higher H, one can thereby -~
provide a vulcanizable composition that is less : :.
susceptible toscorch. When vulcanizable compositions ~.
are cured by peroxide curing agent systems, particularly those using individual peroxides such as dicumyl peroxide, as you increase the value of H, by simply adding more oE the peroxide curin~ agent, you decrease ST. :
The efficiency of a particular curing agent system, therefore, when used with a given vulcanizable composit.ion, and cured at a given temperature, can be determined by multiplying H by ST / CT - ST or, as shown in Equation I; ~ `
T (I) CT T .
The numerical ef~ic:lency (E) of the arbitrary curing agent system shown graphically in Figure 1 there~ore, would, be E = H x ST = (50) (2.l) = 30.9 ~ 5.5 - 2.1 .
To further illustrate the utility of this method, for the purposes of comparitively evaluating different :
vulcanizable composîtions, reference is made to Figure 2 of the drawings in which there is graphically presented typical Monsanto Rheometer curves 1 and 2 that were also -19 .
, f `~
~5564~ 9751 arbitrarily drawn, and which are not based on actual ~ -experiments.
It should be noted from a review of Figure 2 that the cure times CT 1 ~or composition 1 and CT 2 for composition 2, are the same for both compositions and each curve reaches a relatively high torque level with the value of Hl (for composition 1) which is 70, being relatively close to the value of H2 (for composition 2) which is 62. ST 2 (for composition 2), however, is more than a mlnute longer than ST 1 (for composition 1), 3.2 vs 2.0 minutes. Thus, i~ is qulte obvious from a review of these two curves that curve 2 represents the better cure system. If one maintains the same CT, and reaches almost the same maximum cross-link density (H), `
then increasing ST must lead to a better curing system, in accordance with the above definition of E.
A calculation of the relative numerical effi-ciencies of the curable compositions shown graphically in Figure 2 is shown below:
Efficiency (El) of composition 1, based on curve l:
El Hl x STl = (70) (2) = 140 = 35.0 CTl ~ STl ( 6 - 2) 4 Efficiency (E2) of composition 2, based on curve 2:
E2 = H2 x ST2= (62) (3.2)= 198.4 = 70.8 CT2 ~ ST2(6 - 3.2) 2.8 20.
- .:
. .
.. . . .
. ; ~ .. . . . . .
~S564Z 9751 , ", ' Thus, this efficiency factor, E, is a useful parameter and it can be shown that in fact a higher value for E represen~s a better system, as defined above, and represents improved utility for such better system. The use of this efficiency factor, E, can also apply to comparisons of Rheometer test curves where the maximum cure (H) shown in each curve is vastly different, since the calculation of E is, in effect, a normalization procedure.
The compositions of the present invention have an efficiency factor (E),as determined above, which is at least about 3, and is preferably more than 10 to 15, units of such efEiciency factor above the eEficiency factor o~ such compositions in the absence of the allyl compounds.
The Eollowing examples are merely illustrative of the present invention and are not intended as a limit-ation upon the scope thereof.
General Admixing Procedure The vulcanizable compositions used in Examples 1-36 were all prepared by the following procedure:
100 parts by weight of the ethylene polymer were fluxed in a Banbury mixer at approximately 120C. The additives, i.e., anti-oxidant, and the first and second -peroxides and the allyl compounds, and, where used, other adjuvants, were then added to the fluxed mixture. The resulting composition was then blended for 2-3 minutes and then transferred to a 2-roll mill for sheeting. The hot rolled sheet was then chopped on a hot granulator to yield a chipped product.
21.
, ... .. .
97,~ :
~ S 56 ~
The chips were then compression molded in~o plaques for use in Monsanto Rheometer test procedures.
~11 of the rheometer data which was then obtained on ~he samples, unless otherwise stipulated, was obtained at 360~F. (182.2~C.).
Examples 1-5 Five vulcanizable compositions were prepared as in the General Admixing Procedure utilizing dicumyl peroxide (DCP) as a first peroxide compound with a low density (density of < 0.94) ethylene homopolymer .
- Homopolymer I - ~having a density of 0.919, a melt ~ ~ .
index of 1.6 - 2.2 ~lP, 190C.], cumene hydroperoxide ;
(Cumene ll) as a second peroxide compound and trial.lyl cyanurate (TAC). The compositions are shown, in parts by weight in Table I.
TABLE I
Exampl~s 1 _ 3 4 5 -Homopolymer I 100.0 100.0 100.0 100.0 100.0 DCP 2.0 2.0 1.0 2.0 2.0 TAC - 0.5 l.0 0.5 - ..
Cumene H. - - - 0.5 0.
When tested for Efficiency Factors, as disclose~
above, the compositions of Examples 1-5 had Efficiency Factors, based on the values for H, CT and ST, as disclosed below in Table II.
22.
~ . .
-~ 97 1 TABLE II
Examples 1 2 3 4 5 H 44.0 64.0 44.0 54.024.0 T 5.5 5.0 5.6 4.65.6 ST 1.75 1.5 2.1 1.82.8 E 20.5 27.4 26.4 34.724.1 These results indicate that although the use of TAC or Cumene H alone (Examples 2, 3 & 5) wil] increase the E value of the composition of Example 1, the use of TAC
plus Cumene H provides a much higher E value (Example 4) than would be expected based on the results of Examples 2, 3 and 5.
Examples 6-9 Four vulcanizable compositions were prepared as in Examples 1-5 using ethylene homopolymer I? TAC, Cumene H, and 2,5-dimethyl-2,5-di-tertiary butyl peroxy hexane (2,5-DTBPH) as a first peroxide compound. The compositions are shown, in parts by weight, in Table III.
TABLE III
Examples 6 7 8 9 Homopolymer I 100.0100.0 100.0 100.0 2,5-DTBPH 2.01.0 2.0 1.0 rA~ - 1 .0 - 1 . O
Cumene H - - 0.5 0.5 ," ,. .
23.
~ 5S~4Z
When tested for Efficienc~- Factors, as disclosed above, the Compositions of Examples 6-9 had Efflciency Factors, based on the values of H, CT and ST, as disclosed below in Table IV
TABLE IV .
Examples 6 7 8 9 H 50.0 52.0 32.0 45.0 CT 10.2 9.0 11.0 10.7 ST 2.4 2.8 3.7 4.3 : ; .
E 15.8 23.5 16.2 30.3 These results indicate that although the use of TAC or Cumene H alone (Examples 7-8) wil:L increase the E
value of the composition of Example 6 somewhat, the use oE TAC plus Cumene H provides a much higher E value (Example 9) than would be expected based on the results of Examples 7 and 8.
Examples 10-13 Four vulcanizable compositions were prepared as in Examples 1-5 utilizing homopolymer I, TAC, Cumene H, and ~ , n -bis (tertiary butyl peroxy) cli-isopropyl ben2ene (TBPDIP) as a first peroxide compound. The compositions are shown, in parts by weight, in Table V.
TABLE V
Examples 10 11 12 13 Homopolymer I 100.0 100.0100.0 100.0 TBPDIB 2.0 2.0 1.0 1.0 ~AC - - 1 . O :L . O ,~
Cumene H - 0.5 - 0.5 24.
- ` 9 75 l¢:lSS642 When tested for E:Eficiency Factors, as disclosed ;`
above, the Compositions of Examr,les 10-13 had Efficiency Factors, based on the values for H, CT and ST, as disclosed below in Table VI. ~ .
TABLE VI
Examples 10 11 12 13 H 70.0 63.0 68.062.0 CT 8.7 8.4 7.3 7.2 . .
5T 1.6 2.4 1.3 2.2 E 15.8 25.1 14.127.3 :
These results indicate that since the use of ~AC
alone ~Example 12) decreases the E value of the composition o~ E~ample 10, that the use o TAC plus Cumene H pro~ides a higher E value (Example 13) than would be expected, notwithstanding the increased value of E that might be expected from using Cumene H (Example 11) above. ::
Examples 14-17 Four vulcanizable composi-tions were prepared as in Examples 1-5 utilizing DCP as the first peroxide, TAC, tertiary butyl hydroperoxide (TBH) as the second peroxide, and an ethylene-ethyl acrylate copolymer (copolymer I) which contained 15% by weight o~ ethyl acrylate and had a melt index of 1.6 - 2.2 (lP, 190C). The compositions are shown, in parts by weight, in Table VII.
TABLE VII
Examples 14 15 16 17 :
_ Copolymer I 100.0 100.0 100.0100.0 :.
DCP 2.0 2.0 1.01.0 .
TAC - - l.0l.0 .
TBH - 0.2 - 0.2 25.
.. . , : -~ S 5~ ~2 9751 When tested for Efficiency Factors, as disclosed ~: .
above, the compositions of Examples 14-17 had Efficiency Factors, based on the values of H, CT and ST, as disclosed below in Table VIII
TABLE VIII
Examples 14 15 16 17 H 67.0 44.0 76.0 72.0 C 5.3 5.6 4.9 5.5 T
ST 1.1 2.1 1.13 1.9 E 16.9 25.8 22.9 38.0 These results indicate that although the US2 of TAC or TBH alone (Examples 15-16) will incre~se the E value oE the composition of Example l4, the use of T~C plus TBH
provides a much higher E value (Example 17) than would be expected based on the results of Examples 15-16.
Examples 18-21 Four w lcanizable compositions were prepared as in Examples 1-5 utilizing DCP as the -first peroxide, TAC, TBH as the second peroxide, and an ethylene-vinyl acetate copolymer (Copolymer II) which containecl 10%
by weight of vinyl acetate and had a melt index of 2.0 (lP, 190C). The compositions are shown, in parts by weight, in Table IX.
IA~LE IX
Examples 18 19 20 21 Copolymer II 100.0 100.0 100.0 100.0 DCP 2.0 2.0 1.0 1.0 TAC - - 1.0 1.0 T~l - 0.2 - 0.2 26. ~ t '". ':' ' '' '': ' :
~ ~ 5 ~6~ 9751 ~.
When tested for Efficiency Factors, as disclosed -above, the compositions of Examples 18-21 had Efficiency Factors, based on the values of H, CT and ST, as disclosed below in Table X.
T~BLE X
.
Examples 18 19 20 21 H 73.0 62.0 74.0 79.5 .. ..
CT 4.8 5.2 3.9 4.1 ST 1.05 1.85 1.05 1.7 ~
E 20.4 34.2 27.3 55.2 .
These results indicate that although the use of rrAc or TBH alone (Examples 19-20) will increase the E
value of the composition of Example 18, the use of ~.~C
plus TBH provides a much higher E value (Example 21) `
than would be expected based on the results of Examples 19-20.
Examples 22-25 Four vulcanizable compositions were prepared ..
as in Exa~ples 1-5 utili~ing c~ ' -bis (tertiary-butyl peroxy diisopropyl)benzene(TBPDIP) as the first peroxide, TAC, TB~ and three ethylene polymers. The three polymers were ;~
a high density ( > 0.94) ethylene homopolymer (Homopolymer II) .~:
having a density of 0.96 and a melt index of 8.0 (lP, 190C); ~.
an ethylene-ethyl acryla~e copolymer (Copolymer III) having .
an ethyl acrylate content of 23 weight percent, a density of 0.92 and a melt index of 20 (lP, 190C); and an :
ethylene-ethyl acrylate copolymer (Copolymer IV) having 27.
~SS64Z
an ethyl acrylate content of 18 percent by weight and a melt index of 4.5 ~lP, 190C). Homopolymer II
and Copolymer III were added to the composition as is. Copolymer IV was added to the composition in the form of Formulation I which contained 68 percent by weight of Copolymer IV and 32% by weight of carbon black.
The compositions are shown, in parts by weight, in ;
Table XI.
TABLE XI
Exam~ 22 23 24 25 Homopolymer II10.0 10.0 10.0 10.0 Copolymer III45.0 45.0 45.0 45.0 Formulation I45.0 45.0 45.0 45.0 TBPDIP 1.75 0.8 0.7 0.7 IAC - 0.8 0.7 0.7 TB~ - - - 0.2 When tested for Efficiency Factors, as disclosed above, the compositions of Examples 22-25 had Efficiency Factors, based on the values for H, CT and ST, as 20 disclosed below in Table XII.
TABLE XII
Examples 22 23 24 25 H 100.0 77.0 63.0 71.0 CT 9.0 . 6.9 7.2 7.7 ST 1.7 1.6 2.0 2.5 -E 23.3 23.3 24.2 34.2 28.
' ,' ~, 9751 ' ~qgS5~ 2 These results indicate that although the use of T~C or TBH alone (Examples 23-24) provides little or . .
no increase in the E value of the composition of ~: .
Example 22, the use of ~AC plus TBH provides a substantial ..
increase in the E value (Example 25) of the composition .
of Example 22.
29.
1~556~ 9751 Examples 26-31 Six carbon black filled, vulcanizable compositions were prepared as in Examples 1-5 utilizing dicumyl peroxide (DCP) as the first peroxide, TBH, various unsaturated allyl or acrylate compounds and Copolymer ~lo The compositions contained, as an antioxidantJ polymerl7ed 2~2,4-trimethyl-di-hydroquinoline. The compositions are shown, in parts by weight, in Table XIII.
Table XIII
Examples 26 27 28 29 30 3L
Copolymer II 73.8 73.8 73.8 73.8 73.8 73.8 Carbon black 25.8 25.8 25.8 25.8 25.8 25.8 Antioxidant 0.4 0.4 0.4 0.4 0.4 0.4 DCP 1.6 0.8 0 8 0.8 0.8 0.8 T~H - - 0.2 0.2 0.2 0.2 TAC - 0.8 0.8 - - -TAP - - - 0.7 TMPTM - - - - 1.09 - .
TMPTA ~ O.96 TAP - triallyl phosphate TMPTM = trimethylol propane trimethacrylate TMPTA = trimethylol propane triacrylate Wben tested for Efficiency Factors, as disclo~ed above, the composition of Examples 26-31 had Efficiency Factors, ba~ed on the values of H, CT and ST, as disclosed be:Low in Table XIV.
30.
.. . . . ; . .. ., :
TABLE XIV
Examples 26 27 28 29 30 31 H 83.0 80.0 87.0 74.0 48.040.0 CT 4.2 3.5 4.0 4.0 4.74.1 ST 0.92 1.03 1.4 1.38 1.5 1.1 E 23.3 33.4 46.8 39.0 22.5 18.3 These test results indicate that although the use ;
of TAC alone (Example 27) will improve the E value of the composition of Example 26, the use of TBH plus TAC, or TAP, will further substantially increase the E value of the `
composition of Example 26 over that obtained by the use of TAC alone. Further, the use of the triflmctional acrylate compounds TMPTM and TMPTA has a detrimental efect on the E value o the composition of Example 26, in the presence of TBH.
. ~ . .
Examples 32-36 Five vulcanizable compositions were prepared as in Examples 1-5 utilizing DCP, as the first paroxide, TAC, TBH or cumene hydroperoxide (Cumene H) as the second 20 peroxide, and Homopolymer I. The compositions contained, as an antioxidant, bis(2-methyl-4-hydroxy-5-t-butyl phenyl) sulfide. The compositions are shown, in parts by weight, in Table XV.
. . . .
~,........ .. ~ . . . , : . ... . . .
~055642 , TABLE XV
Examples 32 33 34 35 36 Homopolymer I 100.0 100.0 100.0 100.0 100.0 Antioxidant 0.2 0.2 0.2 0.2 0.2 DCP 2.0 1.0 1.0 2.0 2.0 TAC - 1.0 1.0 0.5 0.5 TBH - - 0.2 - -C~nene H - - - - O,5 When tested for Efficiency Factors, as disclosed 10 above, the compositions of Examples 32-36 had Efficiency Factors, hased on the values of H, CT and ST, as disclosed below in Table XVI.
TABLE XVI
Examples 32 33 34 35 36 H 42.7 48.5 46.0 63.3 49.5 CT 4.7 4.8 5.2 4.2 4.7 ST 1.7 1.9 2.46 1.42 2.15 E 24.2 31.8 41.3 32.3 41.7 These test results indicate that although the 20 use of TAC alone (Examples 33 and 35) will improve the E value o~ the composition of Example 32, the use of .
TBH or Cumene H plus TAC (Examples 34 and 36) will further substantially increase the E value of the composition of Example 32 over that obtained by ~he use of TAC alone.
In all cases the tertiary butyl hydroperoxide was used in the form of a mixture of 90% tertiary butyl hydroperoxide and 10% tertiary butyl alcohol.
32. `;
Claims (30)
1. A scorch resistant vulcanizable composition comprising, in weight ratio, 100 parts by weight of ethylene polymer, about 0.1 to 5.0 parts by weight of at least one first peroxide which has a decomposition half-life of about 0.5 to 4.5 minutes at 160 to 200°C. and has the structure wherein R is a C2 to C12 divalent hydrocarbon radical, R' and R" are the same or different C1 to C12 monovalent hydrocarbon radicals, and n is a whole number of 0 or 1, about 0.1 to 2.0 parts by weight of at least one second peroxide which has a decomposition rate which is at least about 20 to 100 times slower than that of said first peroxide compound said second peroxide being either 2,5-dimethyl-2,5-di-hydroperoxy hexane or a compound having the structure or and about 0.1 to 5.0 parts by weight of at least one allyl compound containing at least three allyl groups.
2. A composition as in Claim 1 in which n = O.
3. A composition as in Claim 2 in which R' = R".
4. A composition as in Claim 3 in which R' and R" are phenyl radicals.
5. A composition as in Claim 3 in which R' and R"
are methyl radicals.
are methyl radicals.
6. A composition as in Claim 1 in which n - 1.
7. A composition as in Claim 6 in which R' = R".
8. A composition as in Claim 7 in which R is an aromatic radical.
9. A composition as in Claim 8 in which R is phenylene .
10. A composition as in Claim 9 in which R' and R" are methyl radicals.
ll. A composition as in Claim 7 in which R is a C2 to C4 linear hydrocarbon radical.
12. A composition as in Claim 11 in which R' and R" are methyl radicals.
13. A composition as in Claim 1 in which the allyl compound contains three allyl groups.
14. A composition as in Claim 13 in which said allyl compound comprises triallyl cyanurate.
15. A composition as in Claim 13 in which said allyl compound comprises triallyl phosphate.
16. A composition as in Claim 13 in which said allyl compound comprises triallyl phosphate.
17. A composition as in Claim 13 in which said allyl compound comprises triallyl ortho format.
18. A composition as in Claim 1 in which the allyl compound contains four allyl groups.
19. A composition as in Claim 18 in which the allyl compound comprises tetra allyloxy ethane.
20. A composition as in Claim 1 in which said ethylene polymer comprises ethylene homopolymer.
21. A composition as in Claim 20 in which said ethylene homopolymer has a density of < 0.94.
22. A composition as in Claim 20 in which said ethylene homopolymer has a density of _> 0.94.
23. A composition as in Claim 1 in which said ethylene polymer is either a copolymer of at least 30 weight percent of ethylene and > 50 up to about 70 weight percent of propylene, or a copolymer of at least 30 weight percent of ethylene and up to < 50 weight percent of at least one other organic compound including propylene which is interpolymeri-zable therewith.
24. A composition as in Claim 23 in which said ethylene copolymer comprises ethylene-vinyl acetate copolymer which contains 50 to <100 weight percent of ethylene and >0 to < 50 weight percent of vinyl acetate.
25. A composition as in Claim 23 in which said ethylene copolymer comprises ethylene-ethyl acrylate copolymer which contains 50 to < 100 weight percent of ethylene and > 0 to < 50 weight percent of ethyl acrylate.
26. A process for preventing the scorching of a vulcanizable composition which is susceptible to scorching during the processing thereof at temperatures of about 120 to 160°C, prior to the intended vulcanization thereof said composition comprising, in weight ratio, 100 parts by weight of ethylene polymer, about 0.1 to 5.0 parts by weight of at least one first peroxide compound which has a decomposition
23. A composition as in Claim 1 in which said ethylene polymer is either a copolymer of at least 30 weight percent of ethylene and > 50 up to about 70 weight percent of propylene, or a copolymer of at least 30 weight percent of ethylene and up to < 50 weight percent of at least one other organic compound including propylene which is interpolymeri-zable therewith.
24. A composition as in Claim 23 in which said ethylene copolymer comprises ethylene-vinyl acetate copolymer which contains 50 to <100 weight percent of ethylene and >0 to < 50 weight percent of vinyl acetate.
25. A composition as in Claim 23 in which said ethylene copolymer comprises ethylene-ethyl acrylate copolymer which contains 50 to < 100 weight percent of ethylene and > 0 to < 50 weight percent of ethyl acrylate.
26. A process for preventing the scorching of a vulcanizable composition which is susceptible to scorching during the processing thereof at temperatures of about 120 to 160°C, prior to the intended vulcanization thereof said composition comprising, in weight ratio, 100 parts by weight of ethylene polymer, about 0.1 to 5.0 parts by weight of at least one first peroxide compound which has a decomposition
23. A composition as in Claim 1 in which said ethylene polymer is either a copolymer of at least 30 weight percent of ethylene and > 50 up to about 70 weight percent of propylene, or a copolymer of at least 30 weight percent of ethylene and up to < 50 weight percent of at least one other organic compound including propylene which is interpolymeri-zable therewith.
24. A composition as in Claim 23 in which said ethylene copolymer comprises ethylene-vinyl acetate copolymer which contains 50 to < 100 weight percent of ethylene and > 0 to < 50 weight percent of vinyl acetate.
25. A composition as in Claim 23 in which said ethylene copolymer comprises ethylene-ethyl acrylate copolymer which contains 50 to < 100 weight percent of ethylene and > 0 to < 50 weight percent of ethyl acrylate.
26. A process for preventing the scorching of a vulcanizable composition which is susceptible to scorching during the processing thereof at temperatures of about 120 to 160°C. prior to the intended vulcanization thereof said composition comprising, in weight ratio, 100 parts by weight of ethylene polymer, about 0.1 to 5.0 parts by weight of at least one first peroxide compound which has a decomposition half-life of about 0.5 to 4.5 minutes at 160 to 200°C. and has the structure wherein R is a C2 to C12 divalent hydrocarbon radical, R' and R" are the same or different C1 to C12 monovalent hydrocarbon radicals, and n is a whole number of 0 or 1, which comprises admixing into said composition, prior to said processing, about 0.1 to 5.0 parts by weight of at least one allyl compound containing at least three allyl groups, about 0.1 to 2.0 parts by weight of a second peroxide compound which has a decomposition rate which is at least about 20 to 100 times slower than that of said first peroxide compound said second peroxide being either 2,5-dimethyl-2,5-di-hydroperoxy hexane or a compound having the structure or and then processing said composition into a desired form and shape and then vulcanizing said formed and shaped composition at a temperature of ?180°C.
27. A vulcanized composition prepared by the process of Claim 26.
28. Electric wire or cable insulated with a vulcanized composition prepared by the process of Claim 26.
29. The composition of Claim 1 in vulcanized form.
30. Electric wire or cable insulated with the composition of Claim 1 in vulcanized form.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US52785474A | 1974-11-27 | 1974-11-27 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1055642A true CA1055642A (en) | 1979-05-29 |
Family
ID=24103201
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA239,206A Expired CA1055642A (en) | 1974-11-27 | 1975-11-03 | Vulcanizable ethylene polymer composition with allyl compounds and process for avoiding scorching thereof |
Country Status (12)
| Country | Link |
|---|---|
| JP (1) | JPS5177646A (en) |
| AU (1) | AU508641B2 (en) |
| BE (1) | BE835965A (en) |
| BR (1) | BR7507825A (en) |
| CA (1) | CA1055642A (en) |
| DE (1) | DE2553106C3 (en) |
| FR (1) | FR2292738A1 (en) |
| GB (1) | GB1535038A (en) |
| IN (1) | IN144418B (en) |
| IT (1) | IT1049813B (en) |
| NL (1) | NL7513802A (en) |
| SE (1) | SE413901B (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6143822A (en) * | 1999-03-18 | 2000-11-07 | Union Carbide Chemicals & Plastics Technology Corporation | Polyethylene crosslinkable composition |
| US6277925B1 (en) | 1999-03-18 | 2001-08-21 | Hercules Incorporated | Allyl compounds, compositions containing allyl compounds and processes for forming and curing polymer compositions |
| CN111065672A (en) * | 2017-08-30 | 2020-04-24 | 陶氏环球技术有限责任公司 | Peroxide-containing polyolefin formulations |
Families Citing this family (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5438342A (en) * | 1977-09-02 | 1979-03-22 | Furukawa Electric Co Ltd:The | Polyolefin composition |
| JPS5556143A (en) * | 1978-10-19 | 1980-04-24 | Asahi Chem Ind Co Ltd | Polyethylene composition for rotational molding with high gloss releasability and impact resistance |
| US4692497A (en) * | 1984-09-04 | 1987-09-08 | Acushnet Company | Process for curing a polymer and product thereof |
| US4546980A (en) * | 1984-09-04 | 1985-10-15 | Acushnet Company | Process for making a solid golf ball |
| US5245084A (en) * | 1988-06-14 | 1993-09-14 | Luperox Gmbh | Mixture suited for crosslinking polymers and process for crosslinking polymers with extension of scorch time |
| DE3820252A1 (en) * | 1988-06-14 | 1989-12-21 | Luperox Gmbh | COMPOUND COMPOUND MIXTURE AND METHOD OF NETWORKING POLYMERS THROUGH EXTENDING THE SCORING TIME |
| JP2799884B2 (en) * | 1989-08-18 | 1998-09-21 | 三菱電線工業株式会社 | Water running prevention composition and water running prevention cable using the same |
| ITMI960029U1 (en) | 1996-01-18 | 1997-07-18 | Atochem Elf Italia | PEROXIDE COMPOSITIONS WITH SCORCH RESISTANCE |
| EP1036805B1 (en) * | 1999-03-18 | 2013-01-09 | Union Carbide Chemicals & Plastics Technology LLC | A polyethylene crosslinkable composition |
| JP5407877B2 (en) * | 2010-01-08 | 2014-02-05 | 日油株式会社 | Ethylene-vinyl acetate copolymer composition and cross-linked product |
| ES2415504T3 (en) * | 2010-12-22 | 2013-07-25 | Borealis Ag | Abrasion Resistant Polyethylene Composition |
| WO2014040237A1 (en) * | 2012-09-12 | 2014-03-20 | Dow Global Technologies Llc | Cross-linkable polymeric compositions, methods for making the same, and articles made therefrom |
| DE102016117664A1 (en) | 2016-09-20 | 2018-03-22 | Rehau Ag + Co | Crosslinkable polymeric composition and crosslinked polymeric composition |
| TW202400702A (en) | 2022-06-16 | 2024-01-01 | 美商陶氏全球科技有限責任公司 | Ultrahigh temperature, low scorch method of making crosslinkable compound compositions |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3661877A (en) * | 1970-05-21 | 1972-05-09 | Reichhold Chemicals Inc | Polymeric compositions and method of preparation |
| JPS578134B2 (en) * | 1972-08-08 | 1982-02-15 |
-
1975
- 1975-11-03 CA CA239,206A patent/CA1055642A/en not_active Expired
- 1975-11-26 JP JP50140869A patent/JPS5177646A/ja active Pending
- 1975-11-26 FR FR7536198A patent/FR2292738A1/en active Granted
- 1975-11-26 IT IT7529674A patent/IT1049813B/en active
- 1975-11-26 BR BR7507825*A patent/BR7507825A/en unknown
- 1975-11-26 NL NL7513802A patent/NL7513802A/en not_active Application Discontinuation
- 1975-11-26 IN IN2258/CAL/75A patent/IN144418B/en unknown
- 1975-11-26 SE SE7513322A patent/SE413901B/en not_active IP Right Cessation
- 1975-11-26 AU AU86949/75A patent/AU508641B2/en not_active Expired
- 1975-11-26 DE DE2553106A patent/DE2553106C3/en not_active Expired
- 1975-11-26 BE BE162193A patent/BE835965A/en not_active IP Right Cessation
- 1975-11-26 GB GB48541/75A patent/GB1535038A/en not_active Expired
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6143822A (en) * | 1999-03-18 | 2000-11-07 | Union Carbide Chemicals & Plastics Technology Corporation | Polyethylene crosslinkable composition |
| US6277925B1 (en) | 1999-03-18 | 2001-08-21 | Hercules Incorporated | Allyl compounds, compositions containing allyl compounds and processes for forming and curing polymer compositions |
| CN111065672A (en) * | 2017-08-30 | 2020-04-24 | 陶氏环球技术有限责任公司 | Peroxide-containing polyolefin formulations |
| CN111065672B (en) * | 2017-08-30 | 2022-05-31 | 陶氏环球技术有限责任公司 | Peroxide-containing polyolefin formulations |
Also Published As
| Publication number | Publication date |
|---|---|
| FR2292738B1 (en) | 1980-04-30 |
| SE7513322L (en) | 1976-05-28 |
| GB1535038A (en) | 1978-12-06 |
| DE2553106A1 (en) | 1976-08-12 |
| JPS5177646A (en) | 1976-07-06 |
| IN144418B (en) | 1978-05-06 |
| AU508641B2 (en) | 1980-03-27 |
| DE2553106C3 (en) | 1983-12-15 |
| AU8694975A (en) | 1977-06-02 |
| NL7513802A (en) | 1976-05-31 |
| BE835965A (en) | 1976-05-26 |
| SE413901B (en) | 1980-06-30 |
| DE2553106B2 (en) | 1979-07-19 |
| BR7507825A (en) | 1976-08-10 |
| IT1049813B (en) | 1981-02-10 |
| FR2292738A1 (en) | 1976-06-25 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4018852A (en) | Composition with triallyl compounds and process for avoiding scorching of ethylene polymer composition | |
| CA1069243A (en) | Composition with selected vinyl compounds and process for avoiding scorching of ethylene polymer composition | |
| CA1055642A (en) | Vulcanizable ethylene polymer composition with allyl compounds and process for avoiding scorching thereof | |
| US10259930B2 (en) | Process for reducing peroxide migration in crosslinkable ethylene-based polymer compositions | |
| CA2695603C (en) | Tree resistant insulation compositions | |
| US3936572A (en) | Electric cable insulated with a corona resistant polyethylene composition containing a silicon additive | |
| CA2627034C (en) | Improved lead-free insulation compositions containing metallocene polymers | |
| US4015058A (en) | Composition with dicumyl peroxide and process for avoiding scorching of ethylene polymer composition | |
| CA1047696A (en) | Compositions with dicumyl peroxide and process for avoiding scorching of ethylene polymer composition | |
| US5889117A (en) | Polymeric compositions for power cables | |
| CA2491013C (en) | Improved insulation compositions containing metallocene polymers | |
| US5191004A (en) | Flame retardant crosslinkable polymeric compositions having improved processability | |
| EP0253766A2 (en) | Stabilized olefin polymer insulating compositions | |
| US4025706A (en) | Composition with peroxides and process for avoiding scorching of ethylene polymer composition | |
| EP2311049B1 (en) | Improved hard grade epr insulation compositions | |
| CA1047200A (en) | Compositions with peroxides and process for avoiding scorching of ethylene polymer composition | |
| US4770902A (en) | Method for covering an electrical conducting means | |
| EP3126410A1 (en) | Crosslinkable polymeric compositions with diallylamide crosslinking coagents, methods for making the same, and articles made therefrom | |
| JPH05112679A (en) | Flame-retarding crosslinkable polymer composition | |
| JP2701014B2 (en) | Rubber composition |