MXPA06007304A - Free-radical crosslinkable polymers:improved process for crosslinking and compositions - Google Patents

Abstract

The present invention is an improved free-radical crosslinking process and free-radical crosslinking polymer compositions. The improved process delivers hotter processing conditions, faster crosslinking, or increased crosslinked densities. The crosslinkable polymeric composition comprises (1) a free-radical crosslinkable polymer, (2) a free-radical inducing species, and (3) a crosslinking-temperature-profile modifier.

Description

POLYMERS UNREGULATED BY FREE RADICALS: IMPROVED PROCESS FOR RETICULATION AND COMPOSITIONS Field of the Invention The present invention relates to polymeric systems that undergo free radical crosslinking reactions. In particular, the invention relates to an improved free radical crosslinking process and to polymeric compositions crosslinkable by free radicals. The improved process provides hotter processing conditions, faster crosslinking or higher crosslink density. Description of the Prior Art A number of polymers can undergo reactions by free radicals. Some of these reactions are beneficial, such as cross-linking, at the desired cross-linking temperature, while others are harmful, such as premature cross-linking, competition or degradation. There is a need to promote beneficial cross-linking reactions while minimizing the impact of harmful reactions. In general, the free-radical crosslinkable polymers are processed for re-binding purposes, the polymers follow a nominal cross-linking temperature profile. The nominal cross-linking temperature profile has three temperature-related portions: (1) a melt processing temperature portion; (2) a transition temperature portion; and (3) a portion of crosslinking temperature. The nominal cross-linking temperature profile is directly related to the characteristics of the polymer and the selected free radical-inducing species (or cross-linking agent). Figure 1 illustrates a typical nominal cross-linking profile. To ensure that only the desired crosslinking reaction occurs, the melt processing temperature is kept low, to avoid premature crosslinking. After the desired level of fusion processing has occurred, the crosslinkable polymer and the free radical-inducing species are subjected to a portion of transition temperature, up to nominal crosslinking temperature. If the free radical-inducing species is an organic peroxide, the nominal cross-linking temperature directly depends on the decomposition temperature of the peroxide. Accordingly, the temperature range of the transition temperature portion is determined by the nominal melt processing temperature on the low temperature end and by the nominal cross-linking temperature on the high temperature end. It is important to note that in some applications fusion processing can occur in a single stage or in more than one stage. As an example of a single stage, the components can be added separately to the hopper of an extruder and mixed by melting at a suitable melt processing temperature. An example of multi-stage melt processing may include a first stage wherein the components are mixed at a temperature above the melting temperature of the polymer but below the nominal decomposition temperature of the free radical-inducing species, and a second stage wherein the mixed composition is transferred to an extruder for further processing. As used herein, the term "melt processing temperature" is defined to include single-stage or multi-stage fusion processing techniques. Because the rate of crosslinking increases gradually with temperature, the temperature difference between the melt processing temperature portion and the crosslinking temperature portion (i.e., the transition temperature portion) can be very large, sometimes more than about 60 degrees Celsius. While the crosslinking temperature changes according to the chosen free radical inducer species, the corresponding temperature range of the transition temperature portion is generally unaffected. Thus, a change in the crosslinking temperature typically requires a corresponding change in the melt processing temperature. For example, in injection molding applications, a low injection temperature (i.e., a portion of melt processing temperature) is required because common organic peroxides decompose over a wide temperature range. For example, practitioners commonly inject crosslinkable polymer compositions containing polymers based on ethylene / propylene / diene monomers and organic dicumyl peroxide in a mold at a temperature of about 100 degrees Celsius and then cure the compositions in the mold at a temperature of wall established at approximately 165 degrees Celsius (i.e., the crosslinking temperature portion). As such, the crosslinking process has a wide transition temperature range of about 65 degrees Celsius, which results in a very long nominal cross-linking temperature profile time, particularly for coarse parts. The nominal cross-linking temperature profile restricts injection molding to those crosslinkable polymers having a suitable melting temperature or a suitable viscosity profile. Similarly, in some applications the technicians extrude crosslinkable polymeric compositions at temperatures no higher than 140 degrees Celsius and then pass the resulting manufactured article through a continuous vulcanization tube at a higher crosslinking temperature, typically in excess of 200 degrees Celsius, to complete the crosslinking. Because the sliding temperature by the speed of the extrusion screw can induce premature crosslinking, the screw speed is kept low and the extrusion output is limited. With crosslinkable polymers based on ethylene / propylene / diene monomers or ethylene / propylene gums, the crosslinkable compositions are typically extruded at a temperature no higher than 120 degrees Celsius, where the extruded article eventually passes through a vulcanization tube continues at a temperature of approximately 210 degrees Celsius. Similarly, the flame retardant, free radical crosslinkable compositions are typically extruded at a temperature. not greater than about 140 degrees Celsius, wherein the extruded article is finally passed through a continuous vulcanization tube at a temperature of about 200-210 degrees Celsius. With chlorinated polyethylene that can be crosslinked by free radicals, an example of a manufacturing method is extrusion. Typically, the crosslinkable polymeric compositions containing chlorinated polyethylene are melt processed in a batch mixer and then subjected to crosslinking conditions in a continuous vulcanization tube, usually at a temperature of about 200 degrees Celsius. When these chlorinated polyethylene compositions are emptied with fillers of small particle size, such as carbon black and silica, intense mixing is required. Unfortunately, intense mixing is limited by temperature and time, to avoid premature crosslinking. In fact, the temperature is often kept at no more than 1 00 degrees Celsius. Also, because the sliding temperature of the extrusion screw can also induce premature crosslinking, the exit velocity of the extruder is limited. The transition temperature for chlorinated polyethylene compositions represents approximately a temperature range of 100 degrees Celsius. This temperature difference has a negative impact on the speed of the line and contributes to a long residence time in the continuous vulcanization tube. To increase injection temperatures or extrusion rates without premature crosslinking, the technicians add burn inhibitors or antioxidants to the compositions. Unfortunately, this approach increases the cycle time to reach the desired level of crosslinking (ie, the cure rate decreases). To solve the reduction in the curing speed, the technicians use longer continuous vulcanization tubes, extruding the polymer or sophisticated formulations of the composition for injection molding or extruded polymers. In accordance with the foregoing, there is a need for an improved process for the crosslinking of crosslinkable polymers by free radicals. The improved process should allow a greater portion of melting temperature than currently achieved in conventional processes, while maintaining current levels of premature crosslinking or further minimizing premature crosslinking. Similarly, the improved process should allow a higher extrusion screw speed than the conventional processes currently practiced, without having any negative impact on premature crosslinking. There is also a need for an improved process for crosslinking free radical crosslinkable polymers, wherein the temperature range of the transition temperature portion is significantly narrower than that provided in conventional processes, also without having a negative impact on crosslinking early. A narrower temperature range will produce a faster process because the polymer transition temperature is minimized. It is also desirable that the transition temperature portion be increased as sharply as possible and have a slope that tends to infinity. In addition, it is desirable that the crosslinking temperature portion have a slope as close to zero as possible. In the context of processing expandable, free radical crosslinkable polymer compositions, the crosslinking temperature profile is complicated by premature crosslinking, as well as by the expansion of the composition within the range between the melt processing temperature and the reticulation. There is a need to minimize the impact of premature crosslinking, to control the emergence / conclusion of expansion and to obtain a faster crosslinking process. For some molding applications, there is also a need to minimize the expansion of the foamed article after removal from the mold, preferably to control subsequent expansion at a rate of less than about 1.5 percent by volume. More preferably, it is desirable to control the subsequent expansion without adding functional groups to the free radical crosslinkable polymers. Each of these necessary process improvements must be achieved without significantly modifying conventional crosslinking equipment. Notably, the need to improve should not require longer continuous vulcanization tubes for the extruded crosslinkable articles. Finally, there is a need for a higher melting temperature portion for the free radical crosslinkable polymers and the need for a faster crosslinking process, without having a detrimental effect on the properties of the articles manufactured by the improved process. There is also a need for polymeric compositions crosslinkable by free radicals, better processing and physical properties. In particular, there is a need for free radical crosslinkable polymer compositions with excellent melt processing characteristics, without premature crosslinking. In some cases, it is additionally desirable that the compositions also have excellent melting strength. BRIEF DESCRIPTION OF THE INVENTION The present invention is an improved process for crosslinking polymers, wherein the improved process provides hotter processing conditions., faster crosslinking or higher crosslink density. The process of the invention comprises the steps of (a) melt processing a crosslinkable polymer composition, (b) forming an article of manufacture from the crosslinkable polymer composition, and (c) crosslinking the crosslinkable polymer composition to obtain an article of manufacture. . The crosslinkable polymer composition comprises (1) a free radical crosslinkable polymer, (2) a free radical producing species and (3) a crosslinking temperature profile modifier. The melt processing step or the crosslinking step occurs at a temperature higher than that conventionally used to crosslink polymers. The higher temperatures allow the cross-linking of previously extruded polymers (due to the high melting temperatures). The increased temperatures also allow an improvement in the speed over the crosslinking profile. The present invention also relates to a polymeric composition crosslinkable by free radicals, which has excellent melt processing and excellent physical properties. The composition of the invention comprises (1) a free radical crosslinkable polymer or a mixture having poor fusion processing properties at nominal melt processing temperatures, (2) a free radical inducing species, and (3) a free radical modifier. cross-linking temperature profile. The crosslinking temperature profile modifier makes possible the melt processing of the free radical crosslinkable polymer or the blend, at a temperature higher than the nominal melt processing temperatures, without premature crosslinking. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 shows a nominal crosslinking temperature profile for a combination of a free radical crosslinkable polymer composition and a free radical inducing species. Figure 2 shows the torque-time curves at 140 degrees Celsius, for crosslinkable polymeric compositions with and without a crosslinking temperature profile modifier. Figure 3 shows torque-time curves at 180 degrees Celsius, for crosslinkable polymer compositions with and without a crosslinking temperature profile modifier. Figure 4 shows torque-time curves at 140 degrees Celsius, for commercially available SuperOhm ™ 3728 crosslinkable peroxide composition, with and without a crosslinking temperature profile modifier. Figure 5 shows torque-time curves at 180 degrees Celsius, for the commercially available SuperOhm ™ 3728 peroxide crosslinkable composition, with and without a crosslinking temperature profile modifier. Figure 6 shows torque-time curves at 150 degrees Celsius, for a high-density polyethylene (a) as the base polymer, (b) with peroxide and (c) with peroxide and a cross-linking temperature profile modifier. Figure 7 shows torque-time curves at 140 degrees Celsius and 150 degrees Celsius, for crosslinkable polymer compositions with and without u? crosslinking temperature profile modifier. Figure 8 shows torque-time curves at 182 degrees Celsius, for crosslinkable polymeric compositions with and without a crosslinking temperature profile modifier. Figure 9 shows the percent decomposition of peroxide at various temperatures, for crosslinkable polymer compositions with and without a crosslinking temperature profile modifier. Figure 10 shows Infrared sweep spectra of Attenuated Total Reflectance of the surface of test samples prepared from compositions containing a crosslinking temperature profile modifier. Figure 1 1 shows torque-time curves at 140 degrees Celsius, for crosslinkable polymeric compositions with and without a crosslinking temperature profile modifier. Figure 12 shows torque-time curves at 177 degrees Celsius, for crosslinkable polymeric compositions with and without a crosslinking temperature profile modifier. Figure 13 shows torque-time curves at 165 degrees Celsius, for crosslinkable polymer compositions, injection mouldable, with various concentrations of a crosslinking temperature profile modifier. Figure 14 shows torque-time curves at 185 degrees Celsius, for crosslinkable polymer compositions, injection mouldable, with various concentrations of a crosslinking temperature profile modifier. Figure 15 shows torque-time curves at 140 degrees Celsius, for crosslinkable polymeric compositions with and without a crosslinking temperature profile modifier. Figure 16 shows torque-time curves at 182 degrees Celsius, for crosslinkable polymeric compositions with and without a crosslinking temperature profile modifier. Figure 17 shows torque-time curves at 140 degrees Celsius, for crosslinkable polymeric compositions with and without a crosslinking temperature profile modifier. Figure 18 shows torque-time curves at 1 82 degrees Celsius, for crosslinkable polymeric compositions with and without a crosslinking temperature profile modifier. Figure 19 shows torque-time curves at 120 degrees Celsius, for crosslinkable polymeric compositions with and without a crosslinking temperature profile modifier. Figure 20 shows torque-time curves at 140 degrees Celsius, for crosslinkable polymeric compositions with and without a crosslinking temperature profile modifier. Figure 21 shows torque-time curves at 182 degrees Celsius, for crosslinkable polymeric compositions with and without a crosslinking temperature profile modifier. Figure 22 shows 140 degree CelF-ius torque-time curves for crosslinkable polymeric compositions with and without a cross-linking temperature profile modifier. Figure 23 shows torque-time curves at 182 degrees Celsius, for crosslinkable polymeric compositions with and without a crosslinking temperature profile modifier. DESCRIPTION OF THE INVENTION In a first embodiment, the process of the invention for preparing a reticulated article of manufacture, comprises the steps of (a) melt processing a crosslinkable polymer composition, (b) forming an article of manufacture from the composition crosslinkable polymer; and (c) crosslinking the crosslinkable polymer composition to obtain an article of manufacture. The crosslinkable polymer composition comprises (1) a free radical crosslinkable polymer, (2) a free radical-inducing species and (3) a cross-linking temperature profile modifier. In the absence of the crosslinking temperature profile modifier, the combination of the free radical crosslinkable polymer and the free radical inducing species has a nominal crosslinking temperature profile. The nominal temperature crosslinking profile comprises a portion of nominal melt processing temperature, a nominal transition temperature portion and a nominal crosslinking temperature portion. The crosslinking temperature profile modifier allows to raise the temperature of the melt processing temperature portion and reduce the transition temperature portion. Accordingly, in the process of the invention, the melt processing step occurs at a temperature higher than the nominal melt processing temperature of the combination. The crosslinking temperature profile modifier substantially suppresses the premature crosslinking of the free radical crosslinkable polymer at the melt processing temperature. For example, when the free radical-inducing species is an organic peroxide with an appreciable rate of decomposition at the melt processing temperature, the crosslinking temperature profile modifier suppresses premature cross-linking of the polymer. The combination of the free-radical crosslinkable polymer and the free radical-inducing species (without a cross-linking temperature profile modifier) achieves a nominal induction time (to.o4n) at the nominal melt processing temperature. The term "nominal induction time" as used herein, means the amount of time required for the torque value, measured by a moving die rheometer (RDM) to increase by 0.04 pounds-inch above the minimum torque at the nominal fusion processing temperature, 1 00 cycles per minute, and an arc of 0.5 degrees. The nominal induction time is alternatively referred to as time to establish the torque increase (testabiecer) - At the nominal fusion processing temperature, the crosslinkable polymer composition achieves an improved induction time (t0.0 ¡) at least 2 times higher than the nominal induction time. Preferably, the improved induction time is at least 3 times greater than the nominal induction time. More preferably, the improved induction time is at least 5 times greater. At the high melt processing temperature, the crosslinkable polymer composition maintains an induction time equal to or greater than the nominal induction time. Preferably, the crosslinkable polymer composition reaches the same degree of cure or a higher degree of cure than the combination would achieve in the absence of the crosslinking temperature profile modifier. While the induction time can generally facilitate the description of the improved process, TS1 is a useful attribute for determining premature crosslinking for certain crosslinkable polymeric compositions. The term "TS1" as used herein, means the amount of time required for the torque value, as measured by a moving die rheometer (RDM) to increase by 1.0 pounds-inch above the torque. minimum at the nominal fusion processing temperature, 100 cycles per minute and an arc of 0.5 degrees. Generally, TS 1 would be used with those crosslinkable polymer compositions having (a) a nominal induction time of less than 1 minute at the nominal melt processing temperature, (b) a difference of MH and ML at least greater than 1 pound - inch (ie, MH - ML >; 1 at the nominal melt processing temperature, and / or (c) a maximum torque (MH) at the nominal crosslinking temperature, substantially greater than 1 pound-inch. Preferably and in the absence of the crosslinking temperature profile modifier, these compositions have a TS1 greater than about 20 minutes at their nominal melt processing temperature. In those compositions, the crosslinking temperature profile modifier allows the crosslinkable polymer composition to reach at least the same TS1 at a melt processing temperature higher than the nominal melt processing temperature. Preferably, the transition temperature portion (i.e., the temperature difference between the melt processing temperature and the crosslinking temperature) can be decreased by at least 5 percent, while keeping the TS1 desirable. The present invention is useful in films for wires and cables, for footwear (eg, greenhouse, shrinkage and elastic), thermoplastic engineering, flame retardants, reactive compounds, thermoplastic elastomers, thermoplastic vulcanization, in the automotive area, in replacement of vulcanized rubber , in the field of construction, automotive, furniture, foams, wetting, adhesives, paintable substrates, dyeable polyolefins, moisture cures, nanocomposites, compatibilizing agents, printing, steel replacement, waxes, fit, calendering sheets, in the area medical, dispersion, co-extrusion, cement / plastic reinforcement, food packaging, non-woven fabrics, paper modifiers, multi-layer containers, sports articles, oriented structure and surface treatment applications. Suitable articles of manufacture include electrical power cable installations (including insulations for extra high voltage (EAV), high voltage (AV), medium voltage (MV) and low voltage (BV)), semiconductor wire and cable (including semiconductor insulation protections), wire and cable coatings (including automotive flame retardant cable insulation) and jackets (including jackets for industrial cables), cable accessories, shoe soles, multi-component shoe soles (including polymers of different densities and types), window seals, gaskets, profiles, durable articles, ultra-stretchable rigid tape, inserts for punched tires, construction panels, composites (eg, wood composites), pipes, foams and fibers (including bonding fibers and elastic fibers). A variety of polymers is useful in the present invention. In addition, many polymers that have hitherto not been suitable for free radical crosslinking are useful in the present invention. Notably, polymers having a high melting temperature are now suitable for free radical crosslinking. In particular, the present invention is useful with free radical crosslinking polymers having a melting temperature equal to or greater than about 130 degrees Celsius or a short nominal induction time. An example of a free radical crosslinking polymer having a high melting temperature is high density polyethylene. For example, the present invention is particularly useful for combinations of a free radical crosslinkable polymer and a free radical inducing species having a nominal induction time of less than about 5 minutes or even less than about one minute. Preferably, the free radical crosslinkable polymer is based on hydrocarbons. Suitable hydrocarbon-based polymers include ethylene / propylene / diene monomers, ethylene / propylene gums, ethylene / alpha-olefin copolymers, ethylene homopolymers, ethylene / unsaturated ester copolymers, ethylene / styrene interpolymers, halogenated polyethylenes, copolymers of propylene, rubber or natural rubber, styrene / butadiene rubber, styrene / butadiene / styrene block copolymers, styrene / ethylene / butadiene / styrene copolymers, polybutadiene rubber, butyl rubber, chloroprene rubber, chlorosulfonated polyethylene rubber , ethylene / diene copolymer and nitrile rubber, and mixtures thereof. More preferably, the hydrocarbon-based polymer is selected from the group consisting of ethylene / propylene / diene monomers and ethylene / propylene gums. Even more preferably, when the hydrocarbon based polymer is one of these preferable polymers or a mixture thereof, the free radical crosslinkable polymer is present in an amount of between about 20 and about 90 weight percent, the inducing species of Free radicals are present in an amount between about 0.5 and 10 weight percent, and the crosslinking temperature profile modifier is present in an amount between about 0.1 and about 5 weight percent, and the crosslinkable polymer composition. by free radicals it also comprises inorganic fillers in an amount of about 10 to about 70 weight percent. Also, more preferably, the hydrocarbon-based polymer is selected from the group consisting of ethylene / alpha-olefin copolymers and ethylene / unsaturated ester copolymers. Even more preferably, when the hydrocarbon-based polymer is one of these preferred polymers or a mixture thereof, the free radical-crosslinkable polymer is present in an amount of between about 10 and about 85 weight percent, the inducing species. of free radicals is present in an amount of between about 0.5 and 10 weight percent, and the crosslinking temperature profile modifier is present in an amount between about 0.1 and about 5 weight percent, and the polymer composition crosslinkable by free radicals further comprises flame retardant additives, in an amount of between about 15 and about 70 weight percent. With respect to suitable ethylene polymers, free-radical crosslinkable polymers are generally classified into four major groups: (1) highly branched; (2) heterogeneous linear chain; (3) homogeneously branched linear; and (4) substantially linear homogeneously branched. These polymers can be prepared with Ziegler-Natta catalysts, single-site metallocene or vanadium-based catalysts, or single-site catalysts of restricted geometry. Highly branched ethylene polymers include low density polyethylene (LDPE). These polymers can be prepared with a free radical initiator at high temperatures and high pressure. Alternatively, they can be prepared with a coordination catalyst at high temperatures and relatively low pressures. These polymers have a density between about 0.910 and about 0.940 grams per cubic centimeter, measured according to ASTM D-792. Straight chain heterogeneous ethylene polymers include linear low density polyethylene (LDPE), ultra low density polyethylene (PEUBD), very low density polyethylene (LDPE) and high density polyethylene (HDPE). The straight chain low density ethylene polymers have a density between about 0.850 and about 0.940 grams per cubic centimeter and a melt index between about 0.01 and about 100 grams per 10 minutes, measured according to ASTM 1238, condition I. Preferably, the melt index is between about 0.1 and about 50 grams per 10 minutes. Also, preferably the LDPE is an interpolymer of ethylene and one or more alpha-olefins having from 3 to 18 carbon atoms, preferably from 3 to 8 carbon atoms. Preferred comonomers include 1-butene, 4-methyl-1-pentene, 1-hexene and 1-ketene. The ultra low density polyethylene and the very low density polyethylene are known interchangeably. These polymers have a density between about 0.870 and about 0.910 grams per cubic centimeter. High density ethylene polymers are generally homopolymers with a density between about 0.941 and about 0.965 grams per cubic centimeter. Homogeneously branched linear ethylene polymers include homogeneous PEBDL. The uniformly branched / homogeneous polymers are those polymers in which the comonomer is randomly distributed in a given interpolymer molecule and wherein the interpolymer molecules have a similar ethylene / comonomer ratio in that interpolymer. Homogeneously branched substantially linear ethylene polymers include (a) olefin homopolymers of 2 to 20 carbon atoms, such as ethylene, propylene and 4-methyl-1-pentene, (b) interpolymers of ethylene with at least one alpha-olefin of 3 to 20 carbon atoms, an acetylenically unsaturated monomer of 2 to 20 carbon atoms, a diolefin of 4 to 18 carbon atoms or combinations of the monomers, and (c) interpolymers of ethylene with at least one of alpha-olefins of 3 to 20 carbon atoms, diolefins or acetylenically unsaturated monomers, in combination with other unsaturated monomers. These polymers generally have a density between about 0.850 and about 0.970 grams per cubic centimeter. Preferably, the density is between about 0.85 and about 0.955 grams per cubic centimeter, more preferably between about 0.850 and 0.920 grams per cubic centimeter. The ethylene / styrene interpolymers useful in the present invention include substantially random interpolymers prepared by the polymerization of an olefin monomer (eg, ethylene, propylene or alpha-olefin monomer) with an aromatic vinylidene monomer, a monomer of hindered aliphatic vinylidene or a cycloaliphatic vinylidene monomer. Suitable olefin monomers contain from 2 to 20, preferably from 2 to 12 and more preferably from 2 to 8 carbon atoms. Preferred monomers include ethylene, propylene, 1-butene, 4-methyl-1-pentene, 1-hexene and 1-ketene. Most preferred are ethylene and a combination of ethylene with propylene or alpha-olefins of 4 to 8 carbon atoms. Optionally, the polymerization of ethylene / styrene interpolymers can also include ethylenically unsaturated monomers, such as ring-rigid olefins. Examples of rigid ring olefins include norbornene and norbornenes substituted with alkyl radicals of 1 to 10 carbon atoms or aryl of 6 to 10 carbon atoms. The ethylene / unsaturated ester copolymers useful in the present invention can be prepared by conventional high pressure techniques. The unsaturated esters may be alkyl acrylates, alkyl methacrylates or vinyl carboxylates. The alkyl groups may have from 1 to 8 carbon atoms and preferably from 1 to 4 carbon atoms. The carboxylate groups can have from 2 to 8 carbon atoms and preferably from 2 to 5 carbon atoms. The portion of the copolymer attributed to the ester comonomer may be in the range of about 5 to about 50 weight percent, based on the weight of the copolymer, and is preferably in the range of about 10 to 40 weight percent. Examples of the acrylates and methacrylates are ethyl acrylate, methyl acrylate, methyl methacrylate, t-butyl acrylate, n-butyl acrylate, n-butyl methacrylate and 2-ethylhexyl acrylate. Examples of vinyl carboxylates are vinyl acetate, vinyl propionate and vinyl butanoate. The melt index of the ethylene / unsaturated ester copolymers can be in the range of about 0.5 to about 50 grams per 10 minutes. Halogenated ethylene polymers useful in the present invention include fluorinated, chlorinated and brominated olefin polymers. The olefin base polymer can be a homopolymer or an interpolymer of olefins having from 2 to 18 carbon atoms. Preferably, the olefin polymer will be an interpolymer of ethylene with propylene or an alpha-olefin monomer of 4 to 8 carbon atoms. Preferred alpha-olefin comonomers include 1-butene, 4-methyl-1-pentene, 1-hexene and 1-ketene. Preferably, the halogenated olefin polymer is chlorinated polyethylene. Even more preferably, when the halogenated olefin polymer is a chlorinated polyethylene, the free radical crosslinkable polymer is present in an amount between about 20 and about 90 weight percent, the free radical inducing species is present in an amount of between about 0.5 and 10 weight percent and the crosslinking temperature profile modifier is present in an amount of between about 0.1 and about 5 weight percent, and the free radical crosslinkable polymer composition further comprises inorganic fillers in an amount of about 10 and about 65 weight percent. This still more preferred composition is useful for polyolefin-based flame retardant compositions. The present invention is particularly beneficial when the free radical crosslinkable polymer is a propylene polymer, because the crosslinking temperature profile modifier can suppress the cleavage of the propylene polymer. Examples of propylene polymers useful in the present invention include copolymers of propylene with ethylene or other unsaturated comonomer. The copolymers also include terpolymers, tetrapolymers, and the like. Typically, polypropylene copolymers comprise units derived from propylene in an amount of at least about 50 weight percent. Preferably, the propylene monomer is at least about 60 weight percent of the copolymer, preferably at least about 70 percent by weight. The natural gums suitable in the present invention include polymers of isoprene of high molecular weight. Preferably, the natural gum will have an average degree of polymerization of about 5000 and a broad molecular weight distribution. Useful styrene / butadiene rubbers include random copolymers of styrene and butadiene. Typically, these gums are produced by free radical polymerization. The styrene / butadiene / styrene block copolymers of the present invention are a separate phase system. The styrene / ethylene / butadiene / styrene copolymers useful in the present invention are prepared from the hydrogenation of styrene / butadiene / styrene copolymers. The polybutadiene rubber useful in the present invention is preferably a 1,4-butadiene homopolymer. Preferably, the butyl rubber of the present invention is a copolymer of isobutylene and isoprene. Isoprene is typically used in an amount of between about 1.0 and about 3.0 weight percent. For the present invention, polychloropropene rubbers are generally 2-chloro-1,3-butadiene polymers. Preferably, the gum is produced by an emulsion polymerization. Additionally, polymerization can occur in the presence of sulfur, to incorporate crosslinking in the polymer. Preferably, the nitrile rubber of the present invention is a random copolymer of butadiene and acrylonitrile. Other polymers crosslinkable by free radicals include silicone rubber and fluorocarbon gums. Silicone gums include gums with a siloxane structure of the form -Si-O-Si-O-. Fluorocarbon gums useful in the present invention include copolymers or terpolymers of vinylidene fluoride, hexafluoropropylene and tetrafluoroethylene, with a cure site monomer to allow free radical crosslinking. Useful free radical inducing species include organic peroxides, azo-type, bicumerous, oxygen and air free radical initiators. Preferably, the free radical-inducing species is an organic peroxide. Preferred organic peroxides include dicumyl peroxide and Vulcup R. Organic peroxide can be added by direct injection. Oxygen-rich environments can initiate useful free radicals. Preferably, the free radical-inducing species is present in an amount of between about 0.5 and about 10 weight percent, preferably between about 0.5 and about 5.0 weight percent, and even more preferably between about 0.5 and about 2.0 percent in weigh. Useful examples of the crosslinking temperature profile modifier are free radical inhibitors such as (i) stable organic free radicals derived from hindered amines, (ii) iniferters, (iii) organometallic compounds, (iv) aryl azooxy radicals and (v) nitrous compounds. When the induction time is appropriate to describe the improved process, the selection of the crosslinking temperature profile modifiers is based on the determination of whether the modifier will have sufficient impact to generate an induction time at least two times greater than that of the modifier. nominal induction time. When the TS1 is a more appropriate measure, the desired improvement is specific to the application. However, at the nominal melt processing temperature, it is desirable to increase (a) the induction time to more than at least 2 minutes or (b) the time required to reach the MH by at least 5 percent. Stable organic radicals, derived from suitable hindered amines, include 2,2,6,6-tetramethyl piperidinyloxy (TEMPO) and its derivatives. Preferably, the stable organic free radicals derived from hindered amines are bis-TEMPOs, oxo-TEMPO, 4-hydroxy-TEMPO, a 4-hydroxy-TEMPO ether, TEMPO attached to a polymer, PROXYL, DOXYL, butyl-N-oxyl di-tertiary, dimethyl diphenyl-pyrrolidin-1-oxoyl, 4-phosphonooxy-TEMPO or a metal complex with TEMPO. Even more preferably, the stable organic free radical derived from hindered amines is a bis-TEMPO or 4-hydroxy-TEMPO. An example of a bis-TEMPO is bis (1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) sebacate. Iniferters are compounds capable of initiating and terminating free radical reactions. They are also capable of reversibly finishing polymer chains in growth. When the crosslinking temperature profile modifier is an iniferter, it is preferably selected from the group consisting of tetraethylthiuram disulfide, benzyl N, N-diethyldithiocarbamate, dithiocarbamates, polythiocarbamates and S-benzyl dithiocarbamate. Preferably, the crosslinking temperature profile modifier is present in an amount between about 0.1 and about 5.0 weight percent. More preferably, between 0.1 and about 2 weight percent, even more preferably, between 0.1 and about 1 weight percent is present. Still more preferably, the free radical-inducing species with respect to the free radical scavenging species are present in a ratio greater than about 1, preferably between about 20: 1 and about 1: 1. The crosslinking temperature profile modifier and the free radical inducing species can be combined with the free radical crosslinkable polymer in a variety of ways, including direct composition, direct immersion and direct injection. The crosslinkable polymer composition may also contain an organic crosslinker that does not have a carbon-carbon double bond, wherein the organic crosslinker modifier and the crosslinking temperature profile change, synergistically (a) suppresses the crosslinking speed of the free-radical crosslinkable polymer, at temperatures lower than the nominal curing temperature of the free radical-inducing species and (b) improve the cross-linking density at the nominal curing temperature of the free radical-inducing species. Preferably, the organic crosslinking modifier is tris (2,4-di-ferf-butylphenyl) phosphite, poly [[6 - [(1, 1, 3,3-tetramethylbutyl) amino] -s-triazine-2,4 - diyl] [2,2,6,6-tetramethyl-4-piperidyl) im] hexamethylene [2, 2,6,6-tetramethyl-4-piperidyl) imino)], 2 (2'-hydroxy) 3 ', 5, -di-rer-amylphenyl) benzotriazole or mixtures thereof. The crosslinkable polymer composition may also contain a non-polar additive, wherein the additive improves crosslinking performance, without contributing to the migration of the crosslinking temperature profile modifier to the surface of an article of manufacture manufactured from the polymer composition. crosslinkable Some examples include decadiene and polybutadiene. The crosslinkable polymer composition may also contain a curing reinforcement or a coagent to improve the crosslinking performance of the free radical-inducing species, without increasing the amount of free radical-inducing species. Improving the crosslinking performance can include decreasing the process cycle time (e.g., increasing the cure rate) and increasing the crosslink density (e.g., degree of cure). The addition of a curing reinforcement is particularly useful when the free radical crosslinkable polymer is a chlorinated polyethylene. In some cases, the coagents can perform a double function, as a cure reinforcement and as a burn retardant. Useful curing reinforcements include polyvinyl agents and certain monovinyl agents such as dimers of alpha-methylstyrene, allyl pentaerythritol (or pentaerythritol triacrylate or triallyl pentaerythritol), triallyl cyanurate (CTA), TAIC, 4-allyl-2-methoxyphenyl allyl ether and 1,3-di-isopropenylbenzene. Some of these curing reinforcements and other useful curing reinforcements have the following chemical structures.

The crosslinkable polymer composition may also contain catalysts to increase the formation of free radicals.

Suitable examples of catalysts include tertiary amines, cobalt naphthenate, magnesium naphthenate, vanadium pentoxide and quaternary ammonium salt. The crosslinkable polymer composition may also contain a chemical agent or physical blowing agent, thereby making the crosslinkable polymer composition expandable. Preferably, the blowing agent will be a chemical blowing agent.

An example of a useful chemical blowing agent is azodicarbonamide. Other additives are useful in the crosslinkable polymer composition of the present invention. These additives include burn inhibitors, antioxidants, fillers, clays, organic clays, processing aids, carbon black, flame retardants, peroxides, dispersing agents, waxes, coupling agents, mold release agents, light stabilizers, deactivators of metals, ticizers, antistatic agents, bleaching agents, nucleating agents, other polymers and dyes. The crosslinkable polymer compositions can have a high filler content. Other suitable non-halogenated flame retardant additives include alumina trihydrate, magnesium hydroxide, red phosphorus, silica, alumina, titanium oxides, melamine, calcium hexaborate, alumina, carbon nanotubes, wollastonite, mica, silicone polymers, phosphate esters, hindered amine stabilizers, ammonium octamolybdate, hardening compounds, melamine octamolybdate, fluxes, hollow glass microspheres, talc, clay, organo-modified clay, zinc borate, antimony trioxide and expandable graphite. Suitable halogenated flame retardant additives include decabromodiphenyl oxide, decabromodiphenyl ethane, ethylene bis- (tetrabromophthalimide) and dechloro plus. In a preferred embodiment, the present invention is an improved process for preparing a cross-linked article of manufacture.

The crosslinking temperature profile modifier allows to raise the melt processing temperature above the nominal melt processing temperature and the temperature of the crosslinking temperature portion above the nominal crosslinking temperature. Accordingly, in the process of the invention, the melt processing step occurs at a temperature higher than the nominal melt processing temperature and the crosslinking step occurs at a temperature higher than the nominal crosslinking temperature. The combination of the free-radical crosslinkable polymer and the free radical-inducing species achieves a nominal induction time (t0.o n) at the nominal fusion processing temperature. At the nominal melt processing temperature, the crosslinkable polymer composition achieves a better induction time (t0.o ¡) at least 2 times longer than the nominal induction time. Preferably, the improved induction time is at least 3 times greater than the nominal induction time. More preferably, the improved induction time is at least 5 times greater. At the high melt processing temperature, the crosslinkable polymer composition maintains an induction time equal to or greater than the nominal induction time. In still another preferred embodiment, the present invention is an improved process for preparing a cross-linked article of manufacture. In the absence of the crosslinking temperature profile modifier, the combination of the free radical-crosslinkable polymer and the free radical-inducing species has a. profile of nominal cross-linking temperature and a nominal processing speed. The cross-linking temperature profile modifier allows the process to be run at least about five percent faster than the nominal processing speed. The combination also achieves a better induction time (to.o ¡) at least 2 times longer than the nominal induction time, at the nominal fusion processing temperature. In addition, the combination and modifier of the cross-linking temperature profile achieve an induction time equal to or greater than the nominal induction time, at a melt processing temperature higher than the nominal melt processing temperature (processing temperature of major fusion). The higher melt processing temperature is required to achieve a faster processing speed. In this embodiment, the crosslinkable polymer composition is melt processed at the higher melt processing temperature. Preferably, the crosslinking step occurs at a temperature greater than the nominal crosslinking temperature. In another preferred embodiment, the present invention is a process invented to prepare a cross-linked article of manufacture, comprising the steps of: (a) melt processing a crosslinkable polymer composition, (b) shaping an article of manufacture from the crosslinkable polymer composition and (c) crosslinking the crosslinkable polymer composition to obtain an article of manufacture. The crosslinkable polymer composition comprises (1) a free radical crosslinkable polymer that forms free radicals when subjected to a cutting, heating or radiation energy, and (2) a crosslinking temperature profile modifier. In the absence of the crosslinking temperature profile modifier, the combination of the free radical crosslinkable polymer, when subjected to a cutting energy, heat or radiation, has a nominal cross-linking temperature profile. The nominal crosslinking temperature profile comprises a nominal melt processing temperature portion, a nominal transition temperature portion and a nominal crosslinking temperature portion. The crosslinking temperature profile modifier allows to raise the temperature of the melt processing temperature portion and reduce the transition temperature portion. Accordingly, in the process of the invention, the melt processing step occurs at a temperature higher than the nominal melt processing temperature of the combination. The melt processing temperature can be increased, by increasing the cutting energy or the amount of radiation that affects the polymer crosslinkable by free radicals. Specifically, this preferred embodiment is particularly useful in extrusion applications, where the speed of the extrusion screw is set at a higher speed, to obtain a greater output. The combination achieves a nominal induction time at the nominal melt processing temperature. At the nominal melt processing temperature, the crosslinkable polymer composition achieves an improved induction time at least 2 times longer than the nominal induction time. Preferably, the improved induction time is at least 3 times greater than the nominal induction time. More preferably, the improved induction time is at least 5 times greater. In an alternative embodiment of the present invention, the invention is a process for preparing a manufacturing article, comprising the steps of (a) injecting, at an injection temperature, a expandable, free radical crosslinkable polymer composition into a mold, at a mold temperature; (b) heating the expandable crosslinkable polymer composition for a period of time to a sufficient crosslinking temperature to expand and crosslink the expandable crosslinkable polymer composition; (c) removing the expandable crosslinkable polymer composition from the mold; and (d) expanding and crosslinking the expandable crosslinkable polymeric article to obtain a cross-linked and expanded article of manufacture. In the present embodiment, the melt processing temperature would encompass the temperature range covered by the injection temperature and the melting temperature of the composition as the composition fills the mold. As such, the injection temperature can be raised as part of the raising of the melt processing temperature. It is desirable to minimize premature crosslinking during this injection phase of the molding process. The combination achieves a nominal induction time over the nominal melt processing temperature portion. At the nominal melt processing temperature, the expandable crosslinkable polymer composition achieves a better induction time, at least 2 times longer than the nominal induction time. Preferably, the improved induction time is at least 3 times greater than the nominal induction time. More preferably, the improved induction time is at least 5 times greater. In yet another embodiment of the present invention, the invention is a process comprising the steps of (a) injecting at an injection temperature, an expandable crosslinkable polymer composition, into a mold, at a mold temperature; (b) expanding the expandable crosslinkable polymer composition to obtain an expanded crosslinkable polymer composition in the mold; and (c) crosslinking the expanded crosslinkable polymer composition to obtain an expanded crosslinked polymeric article in the mold. In the present embodiment, the melt processing temperature would encompass the temperature range covered by the induction temperature and the melting temperature of the composition as the composition fills the mold. As such, the injection temperature can be raised as part of the raising of the melt processing temperature. It is desirable to minimize premature crosslinking during this injection phase of the molding process. The combination achieves a nominal induction time over the nominal melt processing temperature portion. At the nominal melt processing temperature, the expandable crosslinkable polymer composition achieves an improved induction time at least 2 times greater than the nominal induction time. Preferably, the improved induction time is at least 3 times greater than the nominal induction time. More preferably, the improved induction time is at least 5 times greater. Preferably, after removing the article of manufacture from the mold, the subsequent expansion level is controlled such that it is less than about a change of 1.5 percent by volume. In a more preferred embodiment of the present invention, the invention is a process comprising the steps of (a) injecting at an injection temperature, a crosslinkable polymer composition expandable in a mold, at a mold temperature; (b) crosslinking the expandable crosslinkable polymer composition to a degree necessary to support a stable foam structure; (c) expanding the expandable crosslinkable polymer composition to obtain an expanded crosslinkable polymer composition in the mold; and (d) further crosslinking the expanded crosslinkable polymer composition to obtain a crosslinked polymeric article expanded in the mold. In this preferred embodiment, it is particularly desirable to decouple the crosslinking reaction from the expansion of the polymer composition. The combination reaches a nominal induction time over the nominal melt processing temperature portion. At the nominal fusion processing temperature, the expandable crosslinkable polymer composition achieves an improved induction time at least 2 times larger than the nominal induction time. Preferably, the improved induction time is at least 3 times greater than the nominal induction time. More preferably, the improved induction time is at least 5 times greater. Preferably, after removing the article of manufacture from the mold, the subsequent expansion level is controlled such that it is less than a change of about 1.5 percent by volume. In yet another preferred embodiment, the present invention is a crosslinkable polymer composition comprising a free radical crosslinkable polymer and a crosslinking temperature profile modifier, excluding 2,2,6,6-tetramethyl piperidinyloxy (TEMPO) and derivatives thereof. . In still another preferred embodiment, the present invention is a free radical crosslinkable polymer composition having excellent melt processing and physical properties. The composition of the invention comprises (1) a free radical crosslinkable polymer or a mixture having poor fusion processing properties at nominal melt processing temperatures and (2) a crosslinking temperature profile modifier. The crosslinking temperature profile modifier makes possible the melt processing of the free radical crosslinkable polymer or blend, at a temperature higher than the nominal melt processing temperature, without premature crosslinking. In particular, the present invention is useful with free radical crosslinking polymers having a melting temperature equal to or greater than about 130 degrees Celsius. An example of a free radical crosslinkable polymer having a high melting temperature is high density polyethylene. An example of a mixture having improved melt processing characteristics is a mixture of a linear low density polyethylene and a branched polyethylene, wherein at least one of the polymers mixed in the absence of the crosslinking temperature profile modifier. , would be subject to premature crosslinking under nominal fusion processing conditions. The addition of the crosslinking temperature profile modifier substantially suppresses premature crosslinking, thereby allowing the melt processing of the free radical crosslinkable polymer composition. The composition of the present invention allows the preparation of articles (from the polymer composition crosslinkable by free radicals) with excellent physical properties. In another preferred embodiment, the present invention is an expandable, free radical crosslinkable polymer composition, comprising a free radical crosslinkable polymer, a free radical inducing species, a crosslinking temperature profile modifier and a blowing agent that is selected from the group consisting of chemical blowing agents and physical blowing agents. In a preferred embodiment, the present invention is an article of manufacture prepared by an improved process of the present invention. The benefits of the present inventions are particularly evident in thick articles of manufacture. Any number of processes can be used to prepare the articles of manufacture. Especially useful processes include injection molding, extrusion, blow molding, compression molding, rotational molding, thermoforming, blow molding, powder coating, Banbury batch mixtures, fiber spinning, rotational casting, transfer through compression, lamination and calendering. Suitable articles of manufacture include electrical cable insulation (including insulation for extra high voltage applications (EAV), high voltage (AV), medium voltage (MV) and low voltage (BV)), wire and cable semiconductor items (including semiconductor insulation protections), wire and cable coatings (including automotive flame retardant cable insulation) and jackets (including industrial cable jackets), cable accessories, shoe soles, multi-component shoe soles (including polymers of different densities and types), window seals, gaskets, profiles, durable articles, ultra-stretchable rigid tape, inserts for ponchadas tires, building panels, composites (eg, wood composites), pipes, foams and fibers (including bonding fibers and elastic fibers). In another preferred embodiment, the present invention is an article of manufacture prepared from the novel free radical crosslinkable polymer compositions of the present invention. The article of manufacture may be an accessory for electrical power cables comprising a free radical crosslinkable polymer composition prepared from a composition comprising (a) a free radical crosslinkable polymer that is selected from the group consisting of ethylene monomers / propylene / diene, ethylene / propylene gums and mixtures thereof, in an amount of between about 20 and about 90 weight percent, (b) a free radical inducing species, in an amount of between about 0.5 and 10 percent by weight, (c) a crosslinking temperature profile modifier, in an amount of between about 0.1 and about 5 percent by weight, and (d) inorganic fillers in an amount of between about 10 and about 70 percent in weigh. Another example of a manufacturing article is an electrical power cable comprising a crosslinked insulation prepared from a free radical crosslinkable polymer composition comprising (a) a free radical crosslinkable polymer that is selected from the group consisting of monomers ethylene / propylene / diene, ethylene / propylene gums and mixtures thereof, in an amount of between about 20 and about 90 weight percent, (b) a free radical inducing species, in an amount of between about 0.5 and 10 weight percent, (c) a crosslinking temperature profile modifier, in an amount of between about 0.1 and about 5 weight percent, and (d) inorganic fillers in an amount of between about 10 and about 70 cent in weight. Another electrical power cable of the present invention comprises a crosslinked flame retardant insulation, prepared from a free radical crosslinkable polymer composition comprising (a) a free radical crosslinkable polymer that is selected from the group consisting of copolymers of ethylene / alpha-olefin, ethylene / unsaturated ester copolymers and mixtures thereof, in an amount of between about 10 and about 85 weight percent, (b) a free radical inducing species, in an amount of between about 0.5 and 10 weight percent, (c) a crosslinking temperature profile modifier, in an amount of between about 0.1 and about 5 weight percent, and (d) flame retardants in an amount of between about 15 and about 70. percent in weight. A further example of a manufacturing article, is an electrical power cable comprising a cross-linked semiconductor insulation protection, prepared from a free radical crosslinkable polymer composition comprising (a) a free radical crosslinkable polymer that is selected from group consisting of ethylene / alpha-olefin copolymers, ethylene / unsaturated ester copolymers and mixtures thereof, in an amount of between about 10 and about 85 weight percent, (b) a free radical inducing species, in an amount of between about 0.5 and 10 weight percent, (c) a crosslinking temperature profile modifier, in an amount between about 0.1 and about 5 weight percent, and (d) a conductive filler in an amount sufficient to impart a volume resistivity of less than about 1000 Ohm-m. Preferably, the conductive filler will be present in an amount of between about 20 and about 40 weight percent. Another example is an electrical power cable comprising a crosslinked insulation prepared from a free radical crosslinkable polymer composition comprising (a) a mixture of free radical crosslinkable polymers, comprising a linear low density polyethylene and a branched polyethylene, in an amount of between about 20 and about 90 weight percent, (b) a free radical inducing species, in an amount of between about 0.5 and 10 weight percent, (c) a profile modifier of crosslinking temperature, in an amount of between about 0.1 and about 5 weight percent; and (d) inorganic fillers in an amount of between about 10 and about 70 weight percent. Another example is an electrical power cable comprising a reticulated jacket, prepared from a free radical crosslinkable polymer composition comprising (a) a free radical crosslinkable polymer which is chlorinated polyethylene and which is present in an amount of between about 20 and about 90 percent by weight, (b) a free radical-inducing species, in an amount of between about 0.5 and 10 percent by weight, (c) a cross-linking temperature profile modifier, in an amount of between about 0.1 and about 5 weight percent; and (d) inorganic fillers in an amount of between about 10 and about 65 weight percent. An example of a shoe sole article, comprises an expanded free radical crosslinkable polymer composition, prepared from a composition comprising (a) a free radical crosslinkable polymer that is an ethylene / unsaturated ester copolymer, in an amount between about 10 and about 85 weight percent, 8b) a free radical inducing species, in an amount of between about 0.5 and 10 weight percent, (c) a crosslinking temperature profile modifier, in an amount from about 0.01 to about 5 weight percent, and (d) a blowing agent that is selected from the group consisting of physical blowing agents and chemical blowing agents. EXAMPLES The following non-limiting examples illustrate the invention. Example of a Crosslinking Profile Modifier Comparative Examples 1 and 2 were prepared with Affinity ™ 8200 polyethylene, with a melt index of 5.0 grams per cubic centimeter and a density of 0.87 grams per cubic centimeter. Affinity ™ 8200 polyethylene is available from The Dow Chemical Company. Dicumyl peroxide (DiCup R), available from Geo Specialty Chemicals, was added to each composition, in an amount of about 1.00 per. cent in weight. The crosslinking temperature profile modifier was 4-hydroxy-TEMPO, commercially available in A.H. Marks. The 4-hydroxy-TEMPO was added to the composition of Example 2 in an amount of about 0.20 weight percent. The rest of each composition was polyethylene resin. Both compositions were mixed by melting in a Brabender mixer. For each composition evaluated, the RDM generated torque versus time data. At the set temperature, the RDM was established for a frequency of 100 cycles per minute and an arc of 0.5 degrees. For the test specimens of Comparative Example 1 and Comparative Example 2, the temperature was set at 140 degrees Celsius or 80 degrees Celsius. The particular temperature and the resulting data are shown in Table I. The test specimens weighed approximately 5 grams and were placed between Mylar ™ sheets and then in the RDM for evaluation. The established temperature and the evaluation time were selected based on the final application and composition.

TABLE TS 0.01 - is the time required to obtain a torque increase of 0.01 pounds-inch from the minimum torque. t90 - is the time required to reach 90% of the final cure level. The results of TS 0.01 demonstrate that the crosslinked polymer composition (containing a crosslinking temperature profile modifier) has a significantly longer burn inhibition time than its comparative composition which does not have a crosslinking temperature profile modifier. The results of t90 indicate a similar curing speed between the crosslinkable polymer composition and its comparative composition. See Figures 2 and 3.

Modifier of the Profile of Temperature of Reticulation in a Commercial Composition Comparative Example 3 and Example 4 were prepared with a SuperOhm ™ 3728 peroxide crosslinked composition, which is an ethylene / propylene / diene monomer composition available from Schulman. The composition exemplifying the present invention contained about 0.25 weight percent of the crosslinking temperature profile modifier, 4-hydroxy-TEMPO. The remainder of each composition was the SuperOhm ™ 3728 formulation. Both compositions were melt blended in a Brabender mixer.

TABLE II TS 1 - is the time required to obtain a torque increase of 1 pound-inch from the minimum torque. The results of TS 0.01 and TS 1 show that the crosslinkable polymer composition (containing a crosslinking temperature profile modifier) has a significantly longer burn inhibition time than its comparative composition which does not have the stable organic free radical. The results of t90 indicate a similar curing speed between the crosslinkable polymer composition and its comparative composition. See Figures 4 and 5. Impact of a Crosslinking Temperature Profile Modifier on a High Density Polyethylene Comparative examples 5 and 6 and example 7 were prepared with DGDL-3364 high density polyethylene, which is available in the trade The Dow Chemical Company. Dicumyl peroxide (DiCup R) was added to Comparative Example 5 and Example 7, in an amount of about 1.00 weight percent. The 4-hydroxy-TEMPO crosslinking temperature profile modifier was added to the composition of Example 7 in an amount of about 0.20 weight percent. The remainder of comparative example 5 and example 7 was high density polyethylene. Comparative example 6 was only high density polyethylene resin, without adding crosslinking temperature profile or peroxide modifier.

Figure 6 shows the impact of the crosslinking temperature profile modifier on the establishment of the crosslink at 150 degrees Celsius. Comparative Examples 8. 9. 14, 15. 19. 21. 24 v 26 v Examples 10-13. 16-18. 20, 22, 23, 25 and 27 - Ethylene Polymers A Brabender mixer was used to prepare 40 gram samples of the comparative examples and the examples described in this section. In general, the components as listed in Tables IV and V, in percent by weight, were mixed at 125 ° C for 3 minutes. However, the components of comparative example 26 and example 27 were mixed at 135 ° C because the resin had a relatively high viscosity and melting point. Then, 1.7 weight percent of dicumyl peroxide (DiCup R) was added to each exemplified composition. The compositions were mixed for another 4 minutes. Dicumyl peroxide is available from Geo Specialty Chemicals Inc. The antioxidant Irganox 1088 FF and the cross-linking temperature profile modifier bis (1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) sebacate (the " bis-TEMPO ") is available from Ciba Specialty Chemicals, Inc. The cross-linking temperature profile modifier 4-hydroxy-TEMPO is available in AH Marks. Sartomer SR-350 trimethylolpropane trimethacrylate is available from Sartomer Company, Inc. The crosslinking kinetics of the mixtures were investigated using RDM at 140 ° C (to simulate extrusion conditions when premature crosslinking is not desirable) and at 180 ° C (to simulate vulcanization conditions, in which rapid and effective crosslinking is desirable).

The following resins (see Table III) were used to prepare the exemplified compositions. Each of the resins is available from The Dow Chemical Company.

TABLE III t oí O Ol Ol TABLE IV -fs » 1S DO l-1 Ol O Ol or Ol TABLE V cp o Polyethylene Isolation, Example 28 and Comparative Example 29 An example and a comparative example were prepared with an insulation composition based on polyethylene and organic peroxide DiCup R. The composition exemplifying the present invention also contained 4-hydroxy-TEMPO. The polyethylene composition was the HFDB-4202 composition of peroxide-containing branching retardant insulation, commercially available from The Dow Chemical Company. Dicumyl peroxide (DiCup R) was an organic peroxide and is available commercially from Geo Specialty Chamicals. The 4-hydroxy-TEMPO is available commercially in A. H. Marks. The amounts used to prepare Example 28 and Comparative Example 29 are shown in Table VI in percent by weight. TABLE VI The crosslinking kinetics of Example 28 and Comparative Example 29 were investigated by RDM at 140 degrees Celsius and 150 degrees Celsius (to simulate the conditions of fusion processing when premature crosslinking is not desirable) and at 180 degrees Celsius (to simulate the crosslinking conditions in which rapid and effective crosslinking is desirable). At 140 and 150 degrees Celsius longer induction times are preferred. At 182 degrees Celsius, shorter times are preferable to the desired torque, particularly when accompanied by high crosslink densities (or higher final torque).

Figure 7 shows torque-time curves at 140 degrees Celsius and at 150 degrees Celsius. Figure 8 shows the torque-time curves at 182 degrees Celsius. The crosslinking kinetics of Example 28 and Comparative Example 29, was also investigated by RDM over the temperature range of 150 to 190 degrees Celsius to determine the decomposition rates of the peroxide. The percent decomposition of the peroxide was calculated at each temperature and is shown in Figure 9. Figure 9 indicates that the exemplified composition can reach decomposition rates equivalent to those of the comparative composition and thus provide an adequate crosslinking speed . Example 28 and comparative example 29 were processed through a standard 2.5 inch Davis extruder. The resulting extruded strand was evaluated for its quality. A "clean" strand did not exemplify premature crosslinking. A "failed" strand exemplified premature crosslinking. Table VII shows the process conditions for the melt processing (melting temperature) of the extruded strand. All temperatures are given in degrees Celsius and screw speeds are reported in revolutions per minute (RPM). Comparable flow rates between the compositions were achieved at the same melt temperatures and screw speeds.

TABLE VII Comparative Example 30 and Examples 31-35 In each of Comparative Example 30 and Examples 31-35 a standard crosslinkable polymer composition, containing a peroxide, was used. To each example composition, 0.28 weight percent of the 4-hydroxy-TEMPO cross-linking temperature modifier was added. The 4-hydroxy-TEMPO is available commercially in A. H. Marks. Allyl pentaerythritol (or pentaerythritol triacrylate or triallyl pentaerythritol) is available from Perstorp. 2,4-Diphenyl-4-methyl-1-pentene is available from Aldrich. Sartomer SR 350 trimethylolpropane trimethacrylate and Sartomer SR 507 triallyl cyanurate are available from Sartomer Company, Inc.

TABLE VIII Examples 36-38 (Effect of High Melting Point Stabilizer) Each of examples 36-38 was prepared with Nordel ™ 3722P which are ethylene / propylene / diene monomer pellets, 6.0 weight percent of the profile modifier crosslinking temperature 4-hydroxy-TEMPO and 1.00 weight percent DFDB-5410 BK. The amount of ethylene / propylene / diene monomer pellets and the remaining components are specified in Table VII. The ethylene / propylene / diene monomer pellets (MEPD) contained a peroxide. The ethylene / propylene / diene monomers (MEPD) Nordel ™ 3722P had <1% diene and a Mooney viscosity of 20 to 125 degrees Celsius. It is available commercially from DuPont Dow Elastomers L.L.C. The 4-hydroxy-TEMPO is available commercially in A. H. Marks. DFDB-5410 BK is a color masterbatch and is commercially available from The Dow Chemical Company. Sartomer SR 350 trimethylolpropane trimethacrylate is available from Sartomer Company, Inc. Zinc stearate is commercially available from Baerlocher. All the compositions were mixed by melting in a Brabender mixer. TABLE IX The surfaces of the samples were analyzed by infrared attenuated total reflectance (RTA). The spectra were taken in several different areas of the same sample. The results showed that the smallest amount of 4-hydroxy-TEMPO was detected on the surface of Example 37, while the highest amount was found in Example 38. See Figure 10, which is a graph of the results of the RTA. Master MEPD / Modifier A Mix A master MEPD / modifier A mixer containing a crosslinking temperature profile modifier was prepared with ethylene / propylene / diene monomer pellets Nordel ™ 3722P, zinc stearate, DFDB-5410 BK and 4-hydroxy-TEMPO. The ethylene / propylene / diene monomers (MEPD) Nordel ™ 3722P had < 1% diene and a Mooney viscosity of 20 to 125 degrees Celsius. It is available commercially from DuPont Dow Elastomers L.L.C. Zinc stearate is commercially available in Baerlocher. DFDB-5410 BK is a color masterbatch and is available from The Dow Chemical Compány. The 4-hydroxy-TEMPO is available commercially in A. H. Marks. All the components were mixed by melting in a Banbury mixer. The amounts used to prepare the masterbatch of MEPD / modifier A, are shown in Table X as percentages by weight. TABLE X Master Peroxide / MEPD B Mixture A crosslinkable polymer containing peroxide was prepared in the form of a masterbatch. The amounts used to prepare the peroxide masterbatch / MEPD B are shown in Table XI in percent by weight. TABLE XI The MEPDs consisted of a MEPD or a mixture of MEPDs with -5% diene content and = 40 Mooney viscosity at 125 degrees Celsius. The MEPD (s) are commercially available from DuPont Dow Elastomers L.L.C. The treated calcined clay is commercially available from Engelhard. Zinc stearate is commercially available in Baerlocher. The polymerized 1,2-dihydro-2,2,4-trimethylquinoline is available commercially from R.T. Vanderbilt Company. White mineral oil is commercially available on Citgo. Red lead is available commercially from Rhein Chemie Rubber. The Varox ™ DCP 40KE dicumyl peroxide is a cure accelerator and is available commercially from Geo Specialty Chemicals. Sulfur is commercially available at Rhein Chemie Rubber. Example 39 and Comparative Example 40 An amount of master mix of MEPD / modifier A was added to a quantity of master batch of peroxide / MEPD B to prepare a free radical crosslinkable polymer composition for use in the present invention, example 39. The Example 39 was compared with a quantity of peroxide masterbatch / MEPD B in the absence of the crosslinking temperature profile modifier, comparative example 40. The Varox ™ DCP 40KE dicumyl peroxide is a cure accelerator and is commercially available in Geo Specialty Chemicals. The amounts used to prepare Example 39 and Comparative Example 40 are shown in Table Xll in percent by weight. All components of each composition were melt blended in a Banbury mixer. TABLE Xll Example 39 and comparative example 40 were processed to obtain injection molded articles. Table Xlll shows the process conditions for the melt processing temperature (melting temperature) and the crosslinking temperature (curing temperature) of the molded articles. All temperatures are given in degrees Celsius. All times are reported in minutes. The appearance of the parties is reported in the column entitled "Party." When the exemplified composition and process conditions are not sufficient to make a part, the column entitled "Part" has the legend "NP" which means that there is no part and "Burned" when the composition is reticulated prematurely. TABLE Xlll Master MEPD / Modifier C Mix A master MEPD / modifier C containing a crosslinking temperature profile modifier was prepared with ethylene / propylene / diene monomer pellets Nordel ™ 3722P, Nipol ™ DP-5161 nitrile rubber , 4-hydroxy-TEMPO and dicumiio peroxide. The ethylene / propylene / diene monomers (MEPD) Nordel ™ 3722P had <1% diene and a Mooney viscosity of 20 to 125 degrees Celsius. It is available commercially from DuPont Dow Elastomers L.L.C. Nipol ™ DP-5161 nitrile rubber is commercially available from Zeon Chemicals. The 4-hydroxy-TEMPO is available commercially in A. H. Marks. The dicumyl peroxide (DiCup R) is a cure accelerator and is available commercially from Geo Specialty Chemicals. The amounts used to prepare the master mix of MEPD / modifier C, are shown in Table XIV in percent by weight. All the components were mixed by melting in a Brabender mixer TABLE XIV Mixture Mother of MEPD D A crosslinkable polymer was prepared in the form of a mare mixture. The amounts used to prepare the masterbatch of MEPD D are shown in Table VI in percent by weight. All the components were mixed by melting in a Brabender mixer. TABLE XV The MEPDs consisted of a MEPD or a mixture of MEPDs with = 5% diene content and = 40 Mooney viscosity at 125 degrees Celsius. The MEPD (s) is commercially available from DuPont Dow Elastomers L.L.C. The treated calcined clay is commercially available from Engelhard. Zinc stearate is commercially available in Baerlocher. The polymerized 1,2-dihydro-2,2,4-trimethylquinoline is available commercially from R.T. Vanderbilt Company. White mineral oil is commercially available on Citgo. Red lead is available commercially from Rhein Chemie Rubber. Sulfur is commercially available at Rhein Chemie Rubber. Example 41 and Comparative Example 42 A quantity of master mix of EDPM / modifier C was added to a masterbatch amount of EDPM D to prepare a free radical crosslinkable polymer composition for use in the present invention, example 41. The example 41 was compared to a masterbatch amount of MEPD B in the absence of the crosslink temperature profile modifier, comparative example 42. The amounts used to prepare example 41 and comparative example 42, are shown in Table XVI in percent in weight. All components for composition were melt blended in a Banbury mixer. TABLE XVI The crosslinking kinetics of example 41 and comparative example 42 was investigated using a die-in-motion rheometer (RDM) at 140 degrees Celsius (to simulate processing conditions when premature crosslinking is not desirable) and at 177 degrees Celsius (to simulate crosslinking conditions in which rapid and effective crosslinking is desirable). At 140 degrees Celsius, longer induction times are preferable. At 177 degrees Celsius, short times to the desired torque are preferred, particularly when accompanied by high crosslinking intensities (or a higher final torque). Figure 11 shows touch-time curves at 140 degrees Celsius, while Figure 12 shows the torque-time curves at 177 degrees Celsius. MEPD Example 43 and Comparative Example 44 An example and comparative example MEPD was prepared with ethylene / propylene / diene monomers Nordel ™ 3722P, a low density polyethylene, Kadox 930C zinc oxide, treated Translink 37, calcined clay, Astor 4412 paraffin wax, Agerite MA antioxidant, dicumyl peroxide and DFDB-5410 BK color masterbatch. The MEPD of Example 5 also had 4-hydroxy-TEMPO. The ethylene / propylene / diene Nordei ™ 3722P (MEPD) monomers had < 1% diene and a Mooney viscosity of 20 to 125 degrees Celsius. It is available commercially from DuPont Dow Elastomers L.L.C. The low density polyethylene had a melt index of 2g / 10 minutes and a density of 0.923 grams per cubic centimeter. The Kadox 930C zinc oxide is commercially available from Zinc Corporation of America. The treated Translink 37, calcined clay is commercially available from Engelhard. The Astor 4412 paraffin wax is commercially available at Honeywell. The antioxidant Agerite MA is available commercially from R. T. Vanderbilt Company. The color masterbatch DFDB-5410 BK is commercially available from The Dow Chemical Company. Dicumyl peroxide (DiCup R) is an organic peroxide and is available commercially from Geo Specialty Chemicals. The 4-hydroxy-TEMPO is available commercially in A. H. Marks. The amounts used to prepare Example 43 and Comparative Example 44 are shown in Table XVII in percent by weight. All the components for composition were mixed by melting in a Banbüry mixer. TABLE XVII Example 43 and comparative example 44 were processed to prepare molded injection articles. Table XVIII shows the process conditions for the melt processing temperature (melting temperature) and the crosslinking temperature (curing temperature) for the molded articles. Toaas temperatures are reported in degrees Celsius. All Curing Times are given in seconds. The appearance of the parties is reported in the column entitled "Party." When the exemplified composition and process conditions are not sufficient to make a part, the column entitled "Part" has the legend "NP" which means that there is no part and "Burned" when the composition is reticulated prematurely.

TABLE XVIII MEPD Example 45 and Comparative Example 46 An exemplary peroxide crosslinkable MEPD and a comparative example were prepared with ethylene / propylene / diene monomer pellets Nordel ™ NDR 3722P, carbon black CSX-614, SUNPAR 2280 processing oil and peroxide Dicup organic R. The peroxide crosslinkable MEPD of Example 45 also contained 4-hydroxy-TEMPO. The ethylene / propylene / diene monomers Nordel ™ 3722P (MEPD) had < 1% diene and a Mooney viscosity of 20 to 125 degrees Celsius. It is available commercially from DuPont Dow Elastomers L.L.C. CSX-614 carbon black is commercially available from Cabot Corporation. The SUNPAR ™ 2280 had a viscosity of 475 centistokes at 40 degrees Celsius and is commercially available at Sunoco. The 4-hydroxy-TEMPO is available commercially in A. H. Marks. Dicumyl peroxide (DiCup R) is a curing accelerator and is available commercially from Geo Specialty Chemicals. The amounts used to prepare Example 45 and Comparative Example 46 are shown in Table XIX in percent by weight. All the components of each composition were mixed by melting in a Brabender mixer.

TABLE XIX Example 45 and comparative example 46 were processed to obtain extruded articles. Table XX shows the processing conditions for the melt processing (melting temperature) of the extruded articles. All temperatures are given in degrees Celsius. All screw speeds are given in revolutions per minute (rpm) and all pressures are reported in pounds per square inch (psi). The surface quality of the parts is reported in the column titled "Surface". A "rough" surface is indicative of premature crosslinking. TABLE XX Examples 47-51 - Ethylene Copolymer / Vinyl Acetate Formulations Each of Examples 47-51 used the ethylene / vinyl acetate copolymer Elvax ™ 460 in standard injection molding formulations. The formulations contained 3 weight percent of bis (t-butyl peroxy) diisopropylbenzene Perkadox ™ 1440. 5 weight percent Omyalite ™ 95T calcium carbonate, 0.1 weight percent zinc stearate, 0.1 weight percent mixed antioxidants Irganox ™ B225 and a different amount of the 4-hydroxy-TEMPO cross-linking temperature modifier. The amounts of 4-hydroxy-TEMPO are shown in Table XXI. The ethylene / vinyl acetate copolymer Elvax ™ 460 contained 18 weight percent vinyl acetate and a melt index of 2.5 grams per 10 minutes. The EVA is available commercially from DuPont. The bis (t-butyl peroxy) diisopropylbenzene Perkadox ™ 1440 is commercially available from Akzo Nobel. Omyalite ™ 95T calcium carbonate is commercially available in Omya. Zinc stearate is commercially available in Baerlocher. The mixed antioxidants Irganox ™ B225 is commercially available from Ciba Specialty Chemicals Inc. The 4-hydroxy-TEMPO is commercially available from A. H. Marks. TABLE XXI See Figures 13 and 14, which show the torque-time curves at 165 degrees Celsius and 185 degrees Celsius, respectively, for the exemplified compositions.

Mixture of Polyolefin RF / Modifier E A masterbatch of flame retardant (RF) polyolefin / modifier E containing a crosslinking temperature ile modifier, was prepared with ethylene / vinyl acetate copolymer, white alumina trihydrate (ATH) ) PGA-SD, tetrakismethylene (3,5-di-t-4-hydroxylhydrocinnamate) methane Irganox 1010 ™, curing accelerator Vulcup R and 4-hydroxy-TEMPO. Elvax ™ 460 ethylene / vinyl acetate copolymer contained 18 weight percent vinyl acetate and had a melt index of 2.5 grams per 10 minutes. The EVA is available commercially from DuPont. White alumina trihydrate (ATH) PGA-SD is commercially available in Almatis. tetrakismethylene (3,5-di-t-4-hydroxylhydrocinnamate) methane Irganox 1010 ™ is a primary antioxidant and is commercially available from Ciba Specialty Chemicals Inc. The Vulcup R cure accelerator is commercially available from Geo Specialty Chemicals. The 4-hydroxy-TEMPO is available commercially in A. H. Marks. The amounts used to prepare the polyolefin RF masterbatch / modifier E, are shown in Table XXII in percent by weight. TABLE XXII Peroxide / RF Mother-Mix Polyolefin F A crosslinkable peroxide-containing polymer was selected as the peroxide / RF polyolefin F masterbatch. The selected composition is commercially available under the name of Equistar XL 7414 cross-linkable peroxide compound RF. Example 52 and Comparative Example 53 An amount of the RF masterbatch polyolefin / modifier E was added to an amount of peroxide / RF polyolefin F masterbatch, to prepare a free radical crosslinkable polymer composition for use in the present invention, example 52. Example 52 was compared to the amount of peroxide / RF polyolefin F masterbatch in the absence of the crosslinking temperature ile modifier, comparative example 53. The amounts used to prepare example 52 and comparative example 53 are shown in Table XXIII in percent by weight. TABLE XXIII The crosslinking kinetics of Example 52 and Comparative Example 53 was investigated by RDM at 140 degrees Celsius (to simulate the conditions of fusion essing when premature crosslinking is not desirable) and 182 degrees Celsius (to simulate crosslinking conditions in which it is a fast and effective crosslinking is desirable). At 140 degrees Celsius, longer induction times are preferable. At 182 degrees Celsius, shorter times are preferable to the desired torque, particularly when accompanied by high crosslink densities (or high final torque). At 182 degrees Celsius, the desired initial crosslinking torque is 16.0 pounds-inches. Figure 15 shows the torque-time curves at 140 degrees Celsius, while Figure 16 shows the torque-time curves at 182 degrees Celsius. Example 52 and comparative example 53 were essed to prepare extruded articles. Table XXIV shows the ess conditions for the melt essing (die temperature and melting temperature) of the extruded articles. All temperatures are given in degrees Celsius. All screw speeds are reported in revolutions per minute (RPM) and all pressures are given in pounds per square inch (psi). The surface quality of the parts is reported in the column titled "Surface". A "rough" surface is indicative of premature crosslinking. TABLE XXIV RF Polyolefin Example 54 v Comparative Example 55 An example flame retardant polyolefin and a comparative example were prepared with ethylene / vinyl acetate (EVA) copolymer, white alumina trihydrate (ATH) PGA-SD, Kadox 911P thermal stabilizer, Diestearyl 3-3-thiodiionate (DSTDP), tetrakismethylene (3,5-di-t-butyl-4-hydroxylhydrocinnamate) methane Irganox 1010 ™, curing reinforcement SR 350, coupling agent Silane A-151, zinc stearate and organic peroxide Vulcup R. The flame retardant of example 54 also contained 4-hydroxy-TEMPO. The ethylene / vinyl acetate copolymer Elvax ™ 460 contained 18 weight percent vinyl acetate and a melt index of 2.5 grams per 10 minutes. The EVA is available commercially from DuPont. White alumina trihydrate (ATH) PGA-SD is commercially available in Almatis. The Kadox 911 P thermal stabilizer is commercially available in Zinc Corporation of America. Tetrakismethylene (3,5-di-t-butyl-4-hydroxyhydrocinnamate) methane Irganox 1010 ™, is a primary antioxidant and is commercially available from Ciba Specilty Chemicals Inc. DSTDP is a secondary antioxidant and is available in Trade in Great Lakes Chemical Corporation. The SR 350 curing reinforcement is commercially available from Sartomer Company, Inc. The Silane coupling agent A-151 is available commercially from GE Silicons. Zinc stearate is commercially available in Baerlocher. Vulcup R organic peroxide is commercially available from Geo Specialty Chemicals. The 4-hydroxy-TEMPO is available commercially in A. H. Marks. The amounts used to prepare Example 54 and Comparative Example 55 are shown in Table XXV in percent by weight. All the components for each composition were mixed by melting in a Brabender mixer.

TABLE XXV The crosslinking kinetics of Example 54 and Comparative Example 55 were investigated by RDM at 140 degrees Celsius and 140 degrees Celsius (to simulate the conditions of fusion processing when premature crosslinking is not desirable) and at 182 degrees Celsius (to simulate the crosslinking conditions in which rapid and effective crosslinking is desirable). At 140 degrees Celsius longer induction times are preferred. At 182 degrees Celsius, longer induction times are preferable. At 182 degrees Celsius, shorter times are preferable to the desired torque, particularly when accompanied by high crosslink densities (or higher fi xed torque). Figure 17 shows torque-time curves at 140 degrees Celsius, while Figure 18 shows the torque-time curves at 182 degrees Celsius. Ethylene-based Semiconductor Composition / Vinyl Acetate Comparative Examples 56, 57 and 60 and Examples 58, 59, 61 and 62 Three comparative examples and four examples were prepared with the EVA-based semiconductor composition HFDA-0802 containing peroxide. The compositions exemplifying the present invention also contained 4-hydroxy-TEMPO. In some cases, the exemplified compositions also contained the trially cyanurate curing (CTA) cure. The semiconductor insulation composition HFDA-0802 is commercially available from The Dow Chemical Company. The 4-hydroxy-TEMPO is available commercially in A. H. Marks. Triallyl cyanurate is commercially available from Sartomer Comany, Inc. The amounts used to prepare the comparative examples and the examples are shown in Table XXVI in percent by weight. TABLE XXVI CPE Example 63 and Comparative Example 64 A chlorinated polyethylene crosslinkable with example peroxide and comparative example was prepared with the chlorinated polyethylene CM0836 TYRIN ™. The compositions also contained CSX-618 carbon black, SR350 cure reinforcement and Dicup R organic peroxide. The peroxide crosslinkable composition exemplifying the present invention further contained 4-hydroxy-TEMPO. The chlorinated polyethylene CM0836 TYRIN ™ contained 36% chlorine and a Mooney viscosity of 94 to 121 degrees Celsius. It is available commercially from DuPont Dow Elastomers L.L.C. Carbon black is commercially available from Cabot Corporation. SR350 curing reinforcement is commercially available from Sartomer Company, Inc. Dicumyl peroxide (DiCup R) is an organic peroxide that is commercially available from Geo Specialty Chemicals. The 4-hydroxy-TEMPO is available commercially in A. H. Marks. The amounts used to prepare Example 63 and Comparative Example 64 are presented in Table XXVII in percent by weight. Both compositions were mixed by melting in a Brabender mixer. TABLE XXVII The crosslinking kinetics of Example 63 and Comparative Example 64 were investigated by RDM at 120 degrees Celsius and 140 degrees Celsius (to simulate the conditions of fusion processing when premature crosslinking is not desirable) and at 182 degrees Celsius (to simulate the crosslinking conditions in which rapid and effective crosslinking is desirable). At 120 and 140 degrees Celsius, longer induction times are preferable. At 182 degrees Celsius, shorter times are preferred up to the desired torque, particularly when accompanied by high crosslink densities (or higher final torque). At 205 degrees Celsius, the desired initial crosslinking torque is 40.0 pounds-inches. Figure 19 shows torque-time curves at 120 degrees Celsius, while Figure 20 shows the torque-time curves at 140 degrees Celsius. Figure 21 shows the torque-time curves at 182 degrees Celsius. Example 63 and comparative example 64 were processed to prepare extruded articles. Table XXVIII shows the process conditions for the melt processing (die temperature and melting temperature) of the extruded articles. All temperatures are given in degrees Celsius. All screw speeds are reported in revolutions per minute (RPM) and all pressures are given in pounds per square inch (psi). The surface quality of the parts is reported in the column titled "Surface". A "rough" surface is indicative of premature crosslinking. TABLE XXVIII Polyolefin Plastomer Example 65 and Comparative Example 66 An example polyolefin plastomer and a comparative example plastomer were prepared with the polyolefin plastomer EG 8200 Affinity ™ and the organic peroxide Dicup R. The polyolefin plastomer of Example 1 also contained p- Nítroso-N, N'- Dimethylaniline. The polyolefin plastomer EG 8200 Affinity ™ had a density of 0.87 grams per cubic centimeter and a melt index of 5 g / 10 minutes. The polyolefin plastomer is commercially available from The Dow Chemical Company. The organic peroxide Dicup R is available commercially from Geo Specialty Chemicals. The p-nitroso-N, N'-dimethylaniline is commercially available from Aldrich. The amounts used to prepare Example 65 and Comparative Example 66 are shown in Table XXIX in percent by weight. Both compositions were mixed by melting in a Brabender mixer. TABLE XXIX The crosslinking kinetics of Example 65 and Comparative Example 66 were investigated by RDM at 140 degrees Celsius (to simulate the conditions of fusion processing when premature crosslinking is not desirable) and at 182 degrees Celsius (to simulate the crosslinking conditions in which is desirable rapid and effective crosslinking). At 140 degrees Celsius, longer induction times are preferable. At 182 degrees Celsius, shorter times are preferred up to the desired torque, particularly when accompanied by high crosslink densities (or higher final torque). Figure 22 shows the torque-time curves at 140 degrees Celsius while the Figure 23 shows the torque-time curves at 182 degrees Celsius

Claims (41)

1. CLAIMS 1. An improved process for preparing a crosslinked article of manufacture, comprising the steps of: (a) melt processing a crosslinkable polymer composition comprising (1) a free radical crosslinkable polymer, (2) a free radical inducing species, and (3) a crosslinking temperature profile modifier, at a melt processing temperature greater than the nominal melt processing temperature of a combination of the free radical crosslinkable polymer and the free radical inducing species; (b) shaping an article of manufacture from the crosslinkable polymer composition; and (c) crosslinking the crosslinkable polymer composition at the nominal crosslinking temperature, to obtain an article of manufacture.
2. 2. The improved process of claim 1, wherein the free radical crosslinkable polymer is hydrocarbon based.
3. The improved process of claim 1, wherein the free radical crosslinkable polymer is selected from the group consisting of ethylene / propylene / diene monomers, ethylene / propylene gums, ethylene / alpha-olefin copolymers, ethylene homopolymers , ethylene / unsaturated ester copolymers, ethylene / styrene interpolymers, halogenated polyethylene, propylene copolymers, natural rubber, styrene / butadiene rubber, styrene / butadiene / styrene block copolymers, styrene / ethylene / butadiene / styrene copolymers, polybutadiene gum, butyl rubber, chloroprene gum, chlorosulfonated polyethylene gum, ethylene / diene copolymer and nitrile rubber and mixtures thereof.
4. 4. The improved process of claim 3, wherein the free radical crosslinkable polymer is a propylene polymer and the crosslink temperature profile modifier suppresses the chain cleavage of the propylene polymer.
5. The improved process of claim 1, wherein the free radical producing species is selected from the group consisting of organic peroxides, free radical initiators of the Azo, bicuum, oxygen and air type.
6. 6. The improved process of claim 1, wherein the crosslinking temperature profile modifier is a free radical inhibitor.
7. The improved process of claim 6, wherein the radical inhibitor is selected from the group consisting of (i) stable organic free radicals derived from hindered amines, (ii) iniferters, c (iii) organometallic compounds, (iv) arylooxi radicals and (v) nitroso compounds.
8. The improved process of claim 7, wherein the free radical inhibitor is a stable organic free radical derived from hindered amine, which is selected from the group consisting of 2,2,6,6-tetramethylpiperidinyloxy (TEMPO) and derivatives of the same.
9. 9. The improved process of claim 8, wherein the stable organic free radical is a 2,2,6,6-tetramethylpiperidinyloxy derivative selected from the group consisting of bis- TEMPOs, oxo-TEMPO, 4-hydroxy- TEMPO, esters of 4-hydroxy-TEMPO, TEMPO bonded to polymers, PROXYL, DOXIL, butyl-N-oxyl ditertiary, dimethyldiphenyl-pyrrolidine-1 -oxyl, 4-phosphonoxy-TEMPO and metal complexes with TEMPO.
10. The improved process of claim 7, wherein the free radical inhibitor is an iniferterg selected from the group consisting of tetraethylthiuram disulfide, benzyl N, N-diethyldithiocarbamate, dithiocarbamates, polythiocarbamates and S-benzyl dithiocarbamate. eleven .
11. The improved process of claim 1, wherein the crosslinkable polymer composition reaches the same degree of cure or a higher degree of cure than the combination would achieve in the absence of the crosslinking temperature profile modifier.
12. The improved process of claim 1, wherein the crosslinkable polymer composition further comprises a curing enhancer.
13. 13. The improved process of claim 1, wherein the polymer composition crosslinkable by free radicals further comprises a catalyst for increasing the formation of free radicals, which is selected from the group consisting of tertiary amines, cobalt naphthalene, manganese naphthalene, vanadium pentoxide and quaternary ammonium salts. .
14. 14. An improved process for preparing a crosslinked article of manufacture, comprising the melt processing of a crosslinkable polymer composition comprising: (1) a free radical crosslinkable polymer, (2) a free radical inducing species, and (3) ) a crosslinking temperature profile modifier, at a melt processing temperature greater than the nominal melt processing temperature of a combination of the free radical crosslinkable polymer and the free radical inducing species.
15. 15. An improved process for preparing a crosslinked article of manufacture, comprising the steps of: (a) melt processing a crosslinkable polymer composition comprising: (1) a free radical crosslinkable polymer, (2) a radical inducing species Free, and (3) a crosslinking temperature profile modifier, at a melt processing temperature greater than the nominal melt processing temperature of a combination of the free radical crosslinkable polymer and the free radical inducing species. (b) shaping an article of manufacture from the crosslinkable polymer composition; and (c) crosslinking the crosslinkable polymer composition to obtain an article of manufacture, at a temperature above the nominal crosslinking temperature of the combination of the free radical crosslinkable polymer and the free radical inducing species.
16. 16. An improved process for preparing a crosslinked article of manufacture, comprising the steps of: (a) melt processing a crosslinkable polymer composition comprising: (1) a free radical crosslinkable polymer, (2) a radical inducing species Free, and (3) a crosslinking temperature profile modifier, wherein (i) in the absence of the crosslinking temperature profile modifier, a combination of the free radical crosslinkable polymer and the free radical inducing species, has a high speed of nominal processing and (ii) the crosslinking temperature profile modifier allows the process to run at least about 5 percent faster than the nominal processing speed, and at a melt processing temperature greater than the nominal melt processing temperature of a combination of the free-radical crosslinkable polymer and the free radical-inducing species; (b) shaping an article of manufacture from the crosslinkable polymer composition; and (c) crosslinking the crosslinkable polymer composition to obtain an article of manufacture.
17. The improved process of claim 16, wherein the crosslinking step occurs at a temperature greater than the nominal crosslinking temperature.
18. 18. An improved process for preparing a crosslinked article of manufacture, comprising melt processing a crosslinkable polymer composition comprising: (1) a free radical crosslinkable polymer, (2) a free radical inducing species, and (3) a crosslinking temperature profile modifier, wherein (i) in the absence of the crosslinking temperature profile modifier, a combination of the free radical crosslinkable polymer and the free radical inducing species has a nominal processing speed and (ii) the The crosslinking temperature profile modifier allows the process to be run at least about 5 percent faster than the nominal processing speed, at a melt processing temperature greater than the nominal melt processing temperature of a combination of the radical crosslinkable polymer free and the free radical-inducing species.
19. 19. An improved process for preparing a crosslinked article of manufacture, comprising the steps of: (a) melt processing a crosslinkable polymer composition comprising (1) a free radical crosslinkable polymer that forms free radicals when subjected to an energy of cutting, heat or radiation, and (2) a crosslinking temperature profile modifier, at a melt processing temperature greater than the nominal melt processing temperature of a combination of the free radical crosslinkable polymer and the inducing species. free radicals; (b) shaping an article of manufacture from the crosslinkable polymer composition; and (c) crosslinking the crosslinkable polymer composition at the nominal crosslinking temperature, to obtain an article of manufacture.
20. An improved process for preparing a crosslinked article of manufacture, which comprises melt processing a crosslinkable polymer composition comprising: (1) a free radical crosslinkable polymer that forms free radicals when subjected to cutting, thermal or radiation energy, and (2) a crosslinking temperature profile modifier, at a melt processing temperature greater than the nominal melt processing temperature of a combination of the free radical crosslinkable polymer and the free radical inducing species. twenty-one .
21. The improved process of any of claims 19 or 20, wherein the temperature of the melt processing temperature portion is high with increasing cutting energy.
22. 22. The improved process of any of claims 1-21, wherein, at the melt processing temperature, the induction time is at least equal to the nominal induction time.
23. 23. An improved process for preparing a crosslinked article of manufacture, comprising the steps of: (a) melt processing a crosslinkable polymer composition comprising (1) a free radical crosslinkable polymer, (2) a free radical inducing species , and (3) a crosslinking temperature profile modifier wherein TS1 is an indication of premature crosslinking of a combination of the free radical crosslinkable polymer and the free radical inducing species, at a melt processing temperature greater than the temperature of nominal fusion processing, while maintaining TS 1 at least equal to TS1 of a combination of the free radical crosslinkable polymer and the free radical inducing species, at the nominal melt processing temperature, (b) shaping a article of manufacture from the crosslinkable polymer composition; and (c) crosslinking the crosslinkable polymer composition to obtain an article of manufacture.
24. 24. An improved process for preparing a crosslinked article of manufacture, comprising melt processing a crosslinkable polymer composition comprising: (1) a free radical crosslinkable polymer, (2) a free radical inducing species, and (3) a crosslinking temperature profile modifier, wherein TS1 is an indication of the premature crosslinking of a combination of the free radical crosslinkable polymer and the free radical inducing species, at a melt processing temperature greater than the melt processing temperature nominal, while maintaining the TS 1 at least equal to TS 1 of a combination of the free radical crosslinkable polymer and the free radical inducing species, at the nominal melt processing temperature.
25. 25. The improved process of any of claims 23 or 24, wherein the TS1 of the combination is at least 20 minutes.
26. 26. The improved process of any of claims 23 or 24, wherein, at the melt processing temperature, the processing speed is at least about 5 percent faster than the nominal processing speed.
27. 27. An improved process for preparing an expanded crosslinked article of manufacture, comprising the steps of: (a) injecting an expandable, free radical free crosslinkable polymer composition into a mold at a mold temperature at an injection temperature; the expandable crosslinkable free radical polymer composition comprises: (A1) a free radical crosslinkable polymer; (A2) a species that induces free radicals; (A3) a crosslinking temperature profile modifier; and (A4) a blowing agent that is selected from the group consisting of chemical blowing agents and physical blowing agents; (b) heating the expandable, free radical crosslinkable polymer composition, for a sufficient period until a crosslinking temperature is sufficient to expand and crosslink the expandable crosslinkable polymer composition; (c) removing the expandable, free radical crosslinkable polymer composition from the mold; and (d) expanding and crosslinking the expandable, free radical crosslinkable polymer composition to obtain a cross-linked and expanded article of manufacture.
28. 28. An improved process for preparing an expanded crosslinked manufacturing article, comprising the steps of: (a) injecting an expandable, free radical free crosslinkable polymer composition into a mold at a mold temperature at an injection temperature; the expandable crosslinkable free radical polymer composition comprises: (A1) a free radical crosslinkable polymer; (A2) a species that induces free radicals; (A3) a crosslinking temperature profile modifier; and (A4) a chemical blowing agent; (b) heating the expandable, free radical crosslinkable polymer composition in the mold, for a period sufficient to reach the activation temperature of the blowing agent; (c) expanding the expandable crosslinkable free radical polymeric composition to obtain a polymeric composition crosslinkable by free radicals expanded in the mold; and (d) crosslinking the expanded crosslinkable polymeric composition to obtain a crosslinked and expanded polymer composition in the mold.
29. 29. A manufactured article prepared from the improved process of any of claims 1 to 28.
30. 30. A free-radical crosslinkable polymer composition, comprising:. (a) a free radical crosslinkable polymer having a melting point at least greater than 130 degrees Celsius and (b) a crosslinking temperature profile modifier.
31. 31 A free radical crosslinkable polymer composition, comprising: (a) a mixture of free radical crosslinkable polymers susceptible to premature crosslinking at the nominal melt processing temperature of the mixture, and (b) a crosslinking temperature profile modifier.
32. 32. The free radical crosslinkable polymer composition of claim 31, wherein the mixture of free radical crosslinkable polymers comprises a linear low density polyethylene and a branched polyethylene.
33. 33. A free radical crosslinkable polymer composition, comprising: (a) a free radical crosslinkable polymer, and (b) a crosslinking temperature profile modifier, excluding 2,2,6,6-tetramethylpiperidinyloxy and derivatives of the same.
34. 34. An expandable, free radical crosslinkable polymer composition comprising: (a) a free radical crosslinkable polymer; (b) a free radical-inducing species; (c) a crosslinking temperature profile modifier; and (d) a blowing agent that is selected from the group consisting of chemical blowing agents and physical blowing agents.
35. 35. An accessory for electrical power cables, comprising a free radical crosslinked polymer composition prepared from a composition comprising: (a) a free radical crosslinkable polymer that is selected from the group consisting of ethylene / propylene monomers / diene, ethylene / propylene gums and mixtures thereof, in an amount of between about 20 and about 90 weight percent, (b) a free radical inducing species in an amount of between about 0.5 and 10 percent by weight. weight, (c) a crosslinking temperature profile modifier in an amount of between about 0.1 and about 5 weight percent, and (d) inorganic fillers in an amount of between about 10 and about 70 weight percent.
36. 36. An electrical power cable comprising a reticulated isolation prepared from a free radical crosslinkable polymer composition comprising: (a) a free radical crosslinkable polymer that is selected from the group consisting of ethylene / propylene / diene monomers , ethylene / propylene gums and mixtures thereof, in an amount of between about 20 and about 90 weight percent, (b) a free radical inducing species in an amount of between about 0.5 and 10 percent by weight , (c) a temperature profile modifier, crosslinking in an amount of between about 0.1 and about 5 weight percent, and (d) inorganic fillers in an amount of between about 10 and about 70 weight percent.
37. 37. An electrical power cable comprising a flame retardant, crosslinked insulation, prepared from a free radical crosslinkable polymer composition comprising: (a) a free radical crosslinkable polymer that is selected from the group consisting of copolymers of ethylene / alpha-olefin, ethylene / unsaturated ester copolymers and mixtures thereof, in an amount of between about 10 and about 85 weight percent, (b) a free radical inducing species in an amount of between about 0.5 and 10 percent by weight, (c) a crosslinking temperature profile modifier in an amount of between about 0.1 and about 5 percent by weight, and (d) flame retardants in an amount of between about 1 5 and about 70 percent by weight.
38. 38. An electric power cable comprising a semiconductive, crosslinked insulation prepared from a free radical crosslinkable polymer composition comprising: (a) a free radical crosslinkable polymer that is selected from the group consisting of ethylene / ethylene copolymers. alpha-olefin, ethylene / unsaturated ester copolymers and mixtures thereof, in an amount of between about 10 and about 85 weight percent, (b) a free radical inducing species in an amount of between about 0.5 and 10 percent by weight, (c) a crosslinking temperature profile modifier in an amount of between about 0.1 and about 5 percent by weight, and (d) a conductive filler in an amount of between about 20 and about 40 percent in weigh.
39. 39. An electrical power cable comprising a crosslinked insulation prepared from a free radical crosslinkable polymer composition comprising: (a) a mixture of free crosslinkable polymers, comprising a linear low density polyethylene and a branched polyethylene, in an amount of between about 20 and about 90 weight percent, (b) a free radical producing species in an amount of between about 0.5 and 10 weight percent, (c) a crosslinking temperature profile modifier in an amount of between about 0.1 and about 5 weight percent, and (d) inorganic fillers in an amount of between about 10 and about 70 weight percent.
40. 40. An electrical power cable comprising a reticulated jacket prepared from a free radical crosslinkable polymer composition comprising: (a) a free radical crosslinkable polymer, which is chlorinated polyethylene and is present in an amount of between about 20 and about 90 weight percent, (b) a free radical inducing species in an amount of between about 0.5 and 10 weight percent, (c) a crosslinking temperature profile modifier in an amount of between about 0.1 and about 5 weight percent, and (d) inorganic fillers in an amount of between about 10 and about 65 weight percent.
41. 41 A shoe sole comprising an expanded crosslinked polymer composition prepared from a composition comprising: (a) a free radical crosslinkable polymer, which is an ethylene / unsaturated ester copolymer, in an amount of between about 10 and about 85 weight percent, (b) a free radical inducing species in an amount of between about 0.5 and 10 weight percent, (c) a crosslinking temperature profile modifier in an amount of between about 0.1 and about 5 percent by weight, and (d) a blowing agent that is selected from the group consisting of physical blowing agents and chemical blowing agents.