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Luperox SP2 technology: the ultimate scorch protection for peroxide crosslinking.

Scorch protection over a wide temperature range is critical to improving compounding, crosslinking and productivity when curing elastomers with organic peroxides. Previously, Arkema developed Luperox F40M-SP (refs. 1 and 2), a scorch protected di(t-buty|peroxy)diisopropyl benzene 40% peroxide masterbatch in EPDM, which was specifically formulated for use in EPDM. Despite the commercial successes of the SP peroxide technology, there are manufacturing processes and rubber formulations that require even greater scorch protection. To address these manufacturing challenges, we recently developed the SP2 peroxide technology with an enhanced scorch protected package compared to the original SP grade. The SP2 peroxide technology provides longer scorch time protection for more demanding compounding and crosslinking operations, and is effective in a very wide range of peroxide-crosslinkable elastomers.

This article introduces the new SP2 (enhanced scorch protected) peroxide technology based upon the two most widely used peroxides for crosslinking: dicumyl peroxide and di(t-bu tylperoxy)diisopropylbenzene. Arkema manufactures these peroxides under the trade names of Luperox DC40PSP2 and Luperox F40P-SP2, respectively, while R.T. Vanderbilt will market these two peroxides as Varox DCP-40C-SP2 and Varox 802-40C-SP2.

In this article we will evaluate the crosslinking and compounding performance of the SP2 peroxide technology in the following elastomers: AEM, CPE, EPDM, EVA, EOM and HNBR. We will also show how to use this new SP2 peroxide technology with crosslinking coagents to improve productivity and reduce production costs by providing further decreases in final cure time, with longer scorch times, while maintaining the targeted crosslinking level in several elastomers.

Experimental

The commercial and newly commercial organic peroxides used in this article are: DC40KE - 40% dicumyl peroxide on inert filler: DC40P-SP2--enhanced scorch protected 40% dicumyl peroxide on inert filler: F40KE - 40% di(t-hutylperoxy) diisopropylbenzene on inert filler; F40M-SP - scorch protected 40% assay di(t-bulylperoxy)diisopropylbenzene compounded into an EPDM in a cubed pellet form: and F40P-SP2 - enhanced scorch protected 40% di(t-butylperoxy)diisopropylbenzene on an inert filler.

Elastomers, peroxide formulations and coagents (if used) were mixed using a C.W. Brabender mixer (Plasti-Corder Model EPL-V5502, with an oil-heated mixing head. Model R.E.0-5). Crosslinking evaluations were conducted using an Alpha Technologies MDR 2000 and an RPA (rubber process analyzer) upgraded with a new instrument board and the latest software.

Additional data for this paper were also kindly provided by Zeon Chemicals and R. T. Vanderbilt.

Results and discussion

Compounding and crosslinking AEM--DC40P-SP2 and F40P-SP2

The peroxide curable Vamac AEM copolymers (polyethyleneco-methyl acrylate) made by DuPont offer improved productivity, since there is no need to post-cure when crosslinking with organic peroxides. In a recent Rubber World technical article (ref. 3), Vamac DP and Vamac DHC copolymers were evaluated using the standard grades of dicumyl peroxide and di(t-butylperoxy)diisopropyl-benzene. In this article, we provide data showing how the new DC40P-SP2 and F40P-SP2 (enhanced scorch protected) peroxide grades can provide improved productivity and cost-savings when compounding and crosslinking the DP and DHC copolymers.

AEM is used to produce automotive transmission seals, coolant and power steering hose, wire jacketing (e.g., ignition harnesses), dust boots and in various dynamic applications, e.g., motor mounts and vibration dampers (ref. 4). Producing these precision components requires complete mold filling prior to any crosslinking, which can be difficult when curing at higher temperatures needed for optimum productivity. Our data in table 1 show that DC40P-SP2 and F40P-SP2 provide a significant (~30% to ~50%) increase in scorch time when curing at temperatures of 180[degrees]C and 190[degrees]C. These longer scorch times allow complete mold filling prior to any significant increase in viscosity. Thus, use of the SP2 peroxide technology will help eliminate hot-tear, poor weld lines, scrap and uneven/ non-uniform curing that hurts physical properties, e.g., % compression set.

The SP2 peroxides provide significant increases in scorch time without increasing cure time, to provide optimum productivity. The data in table 1 shows how the cure temperatures of the standard peroxides were reduced by 8 [degrees]-10[degrees]C with the goal of obtaining the same ts2 scorch time produced using the SP2 peroxides at the original higher temperature. Lowering the cure temperature for the standard peroxides did provide the same increased scorch time as the SP2 peroxides, but significantly slowed the crosslinking reaction (i.e., the tc90 cure time was nearly doubled), thus adversely affecting productivity. Clearly, the SP2 peroxides provide a wider processing window to reduce scrap and improve molded part quality while maintaining good productivity. Thus, SP2 peroxides lower the overall production cost of crosslinking AEM copolymers.

The [M.sub.L] (minimum torque) is the robber viscosity at the reported RPA test temperature. As shown in table 1, the SP2 peroxides provide a 20+% lower [M.sub.L] on average compared to the standard peroxide when curing DP and DHC copolymers. Thus, the SP2 peroxides not only provide a longer scorch time, but also give a significantly lower elastomer viscosity during molding. This helps to faithfully fill the mold, thereby producing highly engineered automotive components with more consistent physical dimensions and reducing the amount of out-of-spec scrap. The lower elastomer viscosity is due to the enhanced scorch protection provided by the SP2 technology, which prevents chain extension and/or gelling of the elastomer during mold filling.

Compounding the DP and DHC copolymers with DC40PSP2 or F40P-SP2 provided nearly a three-fold increase in ts2 scorch time compared to the standard DC40 and F40 peroxides, as shown in table 2 and figure 1. The SP2 peroxide technology permits a 10[degrees]C increase in AEM compounding drop-temperature, with no threat of scorch, versus the standard peroxide. Thus, the SP2 peroxide formulation is very useful when going from two-pass to one-pass mixing operations or for increasing mixing speed to increase mixing capacity, thereby reducing the cost of making the compounded AEM.

Compounding and crosslinking CPE for cable jacket insulation--F40P-SP2 and MBM

The benefits of using SP2 technology are shown in table 3 by comparison to a 'control' formulation prepared using Dow Chemical's Tyrin CM0136 CPE blended with F40KE peroxide and trimethylolpropane trimethacrylate (TMPTMA), a crosslinking coagent.

In order to increase crosslinked CPE cable productivity, one must simultaneously increase the extruder screw speed and the speed of the CPE crosslinking reaction without changing the cure temperature. CPE cable is cured in a CV (continuous vulcanization) steam tube of fixed length and internal temperature. To accomplish these increased speeds, greater scorch protection is needed in the extruder due to the faster screw RPM, while modified CPE formulations provide a faster cure without changing temperatures.

In table 3, run 1, the data show that these objectives can be accomplished by using the F40P-SP2 peroxide to increase scorch protection: and the CPE cure speed is increased by re placing TMPTMA with N,N'-(m-phenylene) bismaleimide (MBM), a more reactive and scorchier coagent (ref. 5). The CPE tc90 cure time was decreased by 47% (from 4.3 to 2.3 minutes) due to the MBM coagent, which meant almost doubled productivity without changing the cure temperature. Employing SP2 technology, F40P-SP2 increased the tsl scorch time from 7.2 minutes to 47.8 minutes, a six-fold increase in scorch time protection for the 130[degrees]C CPE extrusion step. Refer to figures 2 and 3, and table 3 for a comparison of F40KE and F40P-SP2 in CPE.

[FIGURE 3 OMITTED]

In summary, the blend of F40P-SP2 peroxide and MBM for crosslinking CPE provides a way to safely increase extruder screw speed without fear of scorch, while doubling productivity by reducing the cure time by 50%, without increasing the cure temperature.

Compounding and crosslinking EPDM--DC4OP-SP2

Crosslinking ExxonMobil Vistalon 2504 EPDM at 177[degrees]C using 11.5 phr DC40P-SP2 provides a dramatic 50% increase in ts2 scorch time protection when compared to 10.0 phr DC40KE (the standard 40% assay dicumyl peroxide). (Refer to tables 4 and 5, and figure 4.) Furthermore, using SP2 technology with dicumyl peroxide increased the scorch time without increasing the cure time at 177[degrees]C (350[degrees]F), i.e., the tc90 cure time of 4.7 minutes remains essentially unchanged. This grade of EPDM is quite popular for injection molding applications, particularly for automotive gaskets, due to its low viscosity (25 Mooney units at 125[degrees]C, ENB content 4.7% and ethylene content 57.5%).

[FIGURE 4 OMITTED]

The data in table 6 and figure 5 shows that compounding this EPDM formulation with DC40P-SP2 at a relatively high drop-temperature of 138[degrees]C (280[degrees]F), provides a 204% increase in ts2 scorch time (from 7.0 to 21.26 minutes), or about three times the original scorch time provided by the standard DC40KE peroxide.

[FIGURE 5 OMITTED]

In summary, using DC40P-SP2 to crosslink EPDM by injection molding would provide better mold fill and a longer injection time, with no change in cure time, while alleviating scorch related problems of hot-tear and scrap. The longer scorch time at compounding temperatures can help to shorten mixing time by allowing use of a one-pass mixing operation or faster mixing speeds. All of these changes can improve productivity and lower the cost of production.

F40M-SP and F4OP-SP2 for curing EPDM

F40M-SP (SP technology) and F40P-SP2 (SP2 technology) were compared to F40KE (standard peroxide) for crosslinking EPDM (table 7, and figures 6 and 7). F40P-SP2 at 7.20 phr provides a significant (43%) increase in ts2 scorch time at 177[degrees]C (350[degrees]F) versus F40KE at 6.26 phr. F40M-SP at 6.26 phr provides a 15% increase in ts2 scorch time at 177[degrees]C. These SP and SP2 perox ides provide the same tc90 cure time as F40KE, i.e., there is no adverse effect on productivity due to the increased scorch time.

[FIGURES 6-7 OMITTED]

F40P-SP2 provides more than double the scorch time protection in EPDM compared to F40M-SP. In addition to the low Mooney viscosity of Vistalon 2504 EPDM, F40M-SP and F40P-SP2 provide 10% lower minimum torque (ML) or viscosity versus F40KE, when curing at 177[degrees]C. This lower viscosity is due to the scorch protection technology provided by these peroxide formulations. The combination of a lower EPDM viscosity with a longer scorch time makes it easier to completely fill the mold during injection, compression or transfer molding operations.

Compounding EPDM at 138[degrees]C using 6.26 phr F40M-SP or 7.20 phr F40P-SP2 provided a 40% and a 130% increase in ts2 scorch time, respectively, versus the 6.26 phr F40KE control (table 8 and figure 8). Several well-known companies (ref. 6) in the USA and Europe have successfully transitioned from a two-pass to a one-pass EPDM compounding operation simply by replacing F40KE with F40M-SP. We expect the new F40PSP2 peroxide to offer an even wider processing window for compounding EPDM, based on our results described above.

[FIGURE 8 OMITTED]

In summary, F40P-SP2 is highly recommended for molding larger and/or more intricate crosslinked EPDM components. F40M-SP and F40P-SP2 provide enhanced mold filling while minimizing hot-tear and scrap issues that reduce productivity and profits when molding EPDM compounds. A wider processing window is available for compounding EPDM when using the SP2 peroxide technology.

Compounding and crosslinking EVA and EOM, polyethylene copolymers--F40P-SP2

Commercially, Evatane EVA, poly(ethylene-co-vinyl acetate), is crosslinked with select organic peroxides for use in semiconductive and low voltage insulation wire and cable, in automotive sound damping crosslinked foam, and in crosslinked athletic, casual and industrial boot soles (ref. 7), among other uses. Evatane EVA is produced by Arkema and is available in several grades ranging from 18% to 42% vinyl acetate (ref. 8). Engage EOM, poly(ethylene-co-octene), is also crosslinked with select organic peroxides and is used in many of the same applications served by EVA. Engage is produced by Dow Chemical and is available in a wide range of different compositions and densities.

An 80:20 ratio of EVA and EOM was crosslinked with 1.5 phr of F40P-SP2 and compared with an equal weight of F40KE (table 9). F40P-SP2 provided equivalent crosslinking efficiency versus F40KE, with a significant 27% increase in ts2 scorch time protection, at 175[degrees]C (347[degrees]F). The ts2 scorch time increased from 0.82 minutes to 1.04 minutes to provide more time for mold fill, especially for thicker injection molded soles and compression molded foamed slabs. At the 130[degrees]C compounding temperature, F40P-SP2 provided a huge 155% increase in the t5 Mooney scorch time, from 22.1 minutes to 56.2 minutes.

The use of select coagents with the peroxides and SP2 technology can help to further tailor the level of crosslinking, cure rate and compounding performance. In table 9, we show data for the evaluation of a blend of 1.0 phr F40P-SP2 and 0.2 phr triallyl cyanurate (TAC). TAC is well-known as an efficient coagent for HDPE, LDPE, LLDPE and various polyethylene co- and terpolymers, like EVA, EOM and EPDM. This blend of F40P-SP2 and TAC coagent provided a 34% increase in ts2 scorch time at 175[degrees]C, versus a 27% increase when using F40P-SP2 without the TAC. Furthermore, there was a desirable 18% decrease in the tc90 cure time at 175[degrees]C (from 8.25 minutes to only 6.76 minutes) when using this peroxide and coagent blend. This translates to an 18% improvement in productivity. The t5 Mooney scorch time at 130[degrees]C was further increased from 56.2 minutes to 66.6 minutes for the F40P-SP2 and TAC blend, compared to F40P-SP2 without TAC.

By selecting from the well-known acrylic, methacrylic, allylic, polybutadiene and N,N'-(m-phenylene)bismaleimide crosslinking coagents (refs. 9 and 10) and using them in blends with the SP or SP2 peroxide technology, it is possible to tailor the desired level of crosslinking, the cure rate and the scorch time performance, when compounding and crosslinking the various elastomers described above.

In summary, a blend of F40P-SP2 and TAC provides good crosslinking of EVA-EOM, with superior scorch time protection at 175[degrees]C versus F40KE. This gives better mold filling and a shorter tc90 cure time, for improved productivity. We have shown that compounding EVA-EOM at 130[degrees]C with this cure system provides a dramatic 200+% increase in the t5 Mooney scorch time versus F40KE, for potential cost savings by reducing the compounding time via a faster mixer speed or by going from a two-pass to a one-pass compounding operation.

Compounding and crosslinking HNBR--DC4OP-SP2

Using a formulation based on Zeon Chemical's Zetpol 2010 HNBR, we evaluated the processing and crosslinking performance of DC40P-SP2 versus DC40KE. As shown in table 10, 9.4 phr of DC40P-SP2 provided the same amount of crosslinking as 8.0 phr of DC40KE, with a significant (20%) increase in the tsl scorch time at 177[degrees]C and no change in tc90 cure time. The minimum torque ([M.sub.L], equivalent to elastomer viscosity) at the RPA test temperature was reduced by 18% with DC40P-SP2 versus the standard peroxide without SP2 technology. Thus, DC40P-SP2 provides the combination of improved elastomer flow and 20% greater mold fill time when compared to the standard 40% dicumyl peroxide. DC40P-SP2 provided a 70% increase in the tsl scorch time at 149[degrees]C for compounding and processing HNBR, versus the standard DC40KE.

In summary, DC40P-SP2 provides significant increases in scorch time protection during compounding and curing of HNBR, while providing a desirable tc90 cure time equivalent to the DC40KE.

F40P-SP2 for curing HNBR

In a recent paper (ref. 11), Mark Jones and Andy Anderson of Zeon Chemical evaluated F40P-SP2 in a formulation based on Zetpol 2010 HNBR. They found that 9.2 phr of F40P-SP2 was required to provide the same level of crosslinking as 8.0 phr of F40KE (table 11). The ts2 scorch time at 170[degrees]C was increased by 23%, significantly increasing mold fill time. There was no loss in productivity using the SP2 peroxide, compared to the standard peroxide, based upon equivalent tc90 cure times. The Zeon researchers found that the t5 Mooney scorch time at 135[degrees]C was nearly doubled F40P-SP2. This provides increased compounding productivity (the possibility to transition from two-pass to one-pass compounding) and reduces overall processing costs when compounding HNBR. The physical properties, such as percent compression set, with F40P-SP2 were found to be equal to, or better than, the standard F40KE peroxide when crosslinking HNBR, as shown in table 11.

Researchers at R.T. Vanderbilt evaluated F40P-SP2 in a formulation based on Therban (Lanxess) C3446 HNBR (ref. 12). In MDR testing at 180[degrees]C, they found that 4.6 phr of F40PSP2 achieved the same level of cure as 4.0 phr of F40KE, but with a ts2 scorch time of 0.99 minutes for F40P-SP2 compared to only 0.66 minutes for F40KE. They also conducted DuPont spider mold flow tests and found a 17+% increase in mold fill with F40P-SP2 compared to the standard E40KE peroxide at 177[degrees]C (figure 9.)

[FIGURE 9 OMITTED]

In summary, independent studies conducted at Zeon Chemicals and R.T. Vanderbilt confirmed good scorch time performance with F40P-SP2 when crosslinking or compounding HNBR. In addition, DuPont spider mold flow tests of HNBR at 177[degrees]C using F40P-SP2, confirmed a significant 17+% increase in mold fill.

Summary and conclusions

Arkema has commercialized Luperox F40M-SP, a scorch protected 40% peroxide-EPDM masterbatch developed exclusively for use in EPDM compounds. Despite the technical and commercial success of the SP grade, the technology was advanced to another level with the recent development of SP2 (enhanced scorch protected) peroxide technology. This newer technology supports applications involving a wide range of elastomers that require even greater scorch time protection during compounding and crosslinking.

In this article, we introduced two new SP2 (enhanced scorch protected) peroxides, DC40P-SP2 and F40P-SP2, based upon dicumyl peroxide and di(t-butylperoxy)diisopropylbenzene. Data were presented showing the results of evaluations of the SP2 peroxide technology in AEM, CPE, EPDM, EVA, EOM and HNBR.

In AEM, the DC40P-SP2 and F40P-SP2 provided a ~30% to ~50% increase in ts2 scorch times at reported cure temperatures, with desirable tc90 cure times, to maintain good productivity during injection, compression and/or transfer molding operations. A three-fold increase in ts2 scorch time was obtained with these peroxides at reported compounding temperatures, providing the possibility of cost-savings by going to a one-pass mixing operation or by increasing mixer speed, without the threat of scorch.

In CPE cable jacket, a blend of F40P-SP2 and MBM coagent provided a way to safely increase the extruder screw speed, due to a six-fold increase in scorch protection at reported compounding temperatures, while doubling productivity by reducing the cure time without increasing the continuous vulcanization (CV) tube temperature.

In EPDM, both DC40P-SP2 and F40P-SP2 provided ~40% to ~50% improvements in scorch time at reported crosslinking temperatures, versus 15% improvement for the F40M-SP grade previously commercialized specifically for EPDM. These two new SP2 grades are recommended for molding larger parts, increasing the number of prints per mold and/or molding more intricate EDPM components. By simply replacing F40KE with F40M-SP in EPDM, end-users have successfully transitioned from two-pass to one-pass mixing of EPDM. We anticipate that DC40P-SP2 and F40P-SP2 will offer greater cost-savings in compounding EPDM.

In EVA-EOM blends for shoe soles, a blend of F40P-SP2 and TAC provided superior scorch time protection during cure and compounding, along with an 18% increase in productivity based upon tc90 cure time.

In HNBR, DC40P-SP2 and F40P-SP2 provided a ~20% increase in scorch time at reported cure temperatures. Data provided by researchers at Zeon Chemicals and R.T. Vanderbill confirmed good scorch time performance with no change in tc90 cure time. DuPont spider mold flow tests confirmed a 17+% increase in mold fill at cure temperatures.

This article is based Oil a paper presented at a meeting of the Rubber Division, ACS (www.rubber.org).

References

(1.) F. Debaud, A. Defrancisci and L.H. Palys, "SP and CST technologies--a new generation of cost-saving curatives in rubber processing," paper 9, ACS Rubber Div., Oct 5-8, 2004; published as "New generation of cost saving curatives," Rubber World, Vol. 232, No. 2, May 2005.

(2.) L. Keromnes, A. Defrancisci, F. Debaud, A. Prebe and L. Palys, "SP and CST technologies--a new generation of cost saving curatives in rubber processing--part 2," paper 14, ACS Rubber Div., Nov 1-3, 2005.

(3.) D. King, E. McBride, D. Mitchell, Z. Shah, Y-T. Wu, K. Kammerer and L. Lefebvre, "AEM dipolymer with improved cure rate and coolpression set," Rubber World, Vol. 231, No. 5. p. 36, February 2005.

(4.) J.F. Hagman, R.E. Fuller, W.K. Witsiepe and R.N. Greene, "Ethylene-acrylic elastomers," 108th Meeting of the ACS Rubber Division, New Orleans, LA, October 7-10, 1975.

(5.) Arnaud Prebe, work performed while working at the Arkema KoP site..

(6.) Private communication.

(7.) "Functional polyolefins," brochure covering Evatane, Lotryl, Lotader, Orevac and Sornol, Arkema (May 24, 2006); website: www.evatane.com.

(8.) "Evatane ethylene vinyl based co-polymers," brochure (2006); website: www.evatane.com.

(9.) "Sartomer product catalog," Sartomer Company; website: www.sartomer.com.

(10.) Vanax MBM is a product of R.T. Vcmderbilt; website: www.rtvanderbilt.com.

(11.) M. Jones and A. Anderson, "Compounding techniques for improved processing of hydrogenated nitrile butadiene rubber compounds," XI Brazilian Congresss of Rubber Technology ABTB, Sao Paulo, SP Brazil (May 10-12, 2006).

(12.) J. Forgue, C. Handy and M. Sheridan, "SP technology peroxide evaluated in HNBR," internal report: R-1853; R. T. Vanderbilt.

by Fabien Debaud, Laurent Keromnes, Alfredo Defrancisci, Joseph M. Brennan cold Leonard H. Pairs. Arkema (len.palys@arkema.com)
Table 1--crosslinking Vamac with
DC40P-SP2 and F40P-SP2

 1 2

Vamac DHC -- --
Vamac DP 100 100
AgeRite Resin D 1 1
Stearic acid 0.5 0.5
Vanfre VAM 0.5 0.5
N550 carbon black 55 55
Vanax MBM 2 2
F40 5 --
F40P-SP2 -- 5.81
DC40 -- --
DC40P-SP2 -- --

Crosslinking with an RPA, 1 deg. arc, 100 cpm

Cure temperature 190[degrees]C 190[degrees]C
 [M.sub.H] (dN-m) 30.80 29.59
 [M.sub.L] (dN-m) 0.83 0.60
% decrease in ML -- 28%
 ts1 (min.) 0.31 0.46
 ts2 (min.) 0.35 0.52
% increase in ts2 -- 49%
 tc90 (min.) 2.05 2.55

Lowering the cure temp. of the standard peroxides to obtain
the same. Longer scorch times of the SP2 peroxide grades.

Cure temperature 180[degrees]C 190[degrees]C
 ts1 (min.) 0.44 0.46
 ts2 (min.) 0.51 0.52
 tc90 (min.) 4.60 2.55

 3 4

Vamac DHC -- --
Vamac DP 100 100
AgeRite Resin D 1 1
Stearic acid 0.5 0.5
Vanfre VAM 0.5 0.5
N550 carbon black 55 55
Vanax MBM 2 2
F40 -- --
F40P-SP2 -- --
DC40 7.98 --
DC40P-SP2 -- 8.62

Crosslinking with an RPA, 1 deg. arc, 100 cpm

Cure temperature 180[degrees]C 180[degrees]C
 [M.sub.H] (dN-m) 29.23 29.75
 [M.sub.L] (dN-m) 0.82 0.71
% decrease in ML -- 13%
 ts1 (min.) 0.32 0.42
 ts2 (min.) 0.36 0.48
% increase in ts2 -- 33%
 tc90 (min.) 2.20 2.39

Lowering the cure temp. of the standard peroxides to obtain
the same. Longer scorch times of the SP2 peroxide grades.

Cure temperature 172[degrees]C 180[degrees]C
 ts1 (min.) 0.42 0.42
 ts2 (min.) 0.49 0.48
 tc90 (min.) 4.32 2.39

 5 6

Vamac DHC 100 100
Vamac DP -- --
AgeRite Resin D 1 1
Stearic acid 0.5 0.5
Vanfre VAM 0.5 0.5
N550 carbon black 55 55
Vanax MBM 2 2
F40 5 --
F40P-SP2 -- 5.88
DC40 -- --
DC40P-SP2 -- --

Crosslinking with an RPA, 1 deg. arc, 100 cpm

Cure temperature 190[degrees]C 190[degrees]C
 [M.sub.H] (dN-m) 36.59 36.33
 [M.sub.L] (dN-m) 0.94 0.64
% decrease in ML -- 32%
 ts1 (min.) 0.30 0.40
 ts2 (min.) 0.33 0.44
% increase in ts2 -- 33%
 tc90 (min.) 2.05 2.10

Lowering the cure temp. of the standard peroxides to obtain
the same. Longer scorch times of the SP2 peroxide grades.

Cure temperature 181[degrees]C 190[degrees]C
 ts1 (min.) 0.37 0.40
 ts2 (min.) 0.43 0.44
 tc90 (min.) 4.13 2.10

 7 8

Vamac DHC 100 100
Vamac DP -- --
AgeRite Resin D 1 1
Stearic acid 0.5 0.5
Vanfre VAM 0.5 0.5
N550 carbon black 55 55
Vanax MBM 2 2
F40 -- --
F40P-SP2 -- --
DC40 7.98 --
DC40P-SP2 -- 9.32

Crosslinking with an RPA, 1 deg. arc, 100 cpm

Cure temperature 180[degrees]C 180[degrees]C
 [M.sub.H] (dN-m) 38.94
 [M.sub.L] (dN-m) 0.97 0.75
% decrease in ML -- 23%
 ts1 (min.) 0.30 0.40
 ts2 (min.) 0.33 0.45
% increase in ts2 -- 36%
 tc90 (min.) 2.37 2.58

Lowering the cure temp. of the standard peroxides to obtain
the same. Longer scorch times of the SP2 peroxide grades.

Cure temperature 172[degrees]C 180[degrees]C
 ts1 (min.) 0.38 0.40
 ts2 (min.) 0.44 0.45
 tc90 (min.) 4.74 2.58

Table 2--mixing Vamac with DC40P-SP2 or,
F40P-SP2 gives three-fold longer scorch time

 1 2 3 4

F40 5.00 -- -- --
F40P-SP2 -- 5.81 -- --
DC40 -- -- 7.98 --
DC40P-SP2 -- -- -- 8.62

Scorch time at various temperatures (RPA, 1 deg. arc, 100 cpm)

Compounding temp. 135[degrees]C 130[degrees]C
 ts1 (min.) 13.89 40.51 12.31 34.44
 ts2 (min.) 22.01 54.84 19.01 44.89

Compounding temp. 145[degrees]C 140[degrees]C
 ts1 (min.) 4.94 15.79 4.43 11.55
 ts2 (min.) 7.65 20.68 6.66 15.02

 5 6 7 8

F40 5.00 -- -- --
F40P-SP2 -- 5.88 -- --
DC40 -- -- 7.98 --
DC40P-SP2 -- -- -- 9.32

Scorch time at various temperatures (RPA, 1 deg. arc, 100 cpm)

Compounding temp. 135[degrees]C 130[degrees]C
 ts1 (min.) 12.45 39.18 10.00 30.44
 ts2 (min.) 19.37 51.07 15.66 38.92

Compounding temp. 145[degrees]C 140[degrees]C
 ts1 (min.) 4.40 13.39 3.56 10.25
 ts2 (min.) 6.75 17.27 5.42 13.06

Table 3--crosslinking CPE with F40P-S2 and coagents for cable jacket

 Control Run 1 Run 2

CPE 100 100 100
N-550 30 30 30
D I D P 30 30 30
CaC[O.sub.3] 125 125 125
MgO 5 5 5
TMPTMA 2 -- --
MBM -- 3 --
TAC -- -- 1.50
F40KE 6 -- --
F40P-SP2 -- 6 4

Curing CPE in an MDR @ 180[degrees]C, 1[degrees] arc
 [M.sub.H] (dN-m) 33.1 32.4 35.5
 [M.sub.L] (dN-m) 4.7 4.0 3.7
 [M.sub.H] - [M.sub.L] (dN-m) 28.4 28.4 31.8
ts2 (min.) 0.5 0.5 0.3
tc90 (min.) 4.3 2.3 3.6
% decrease in tc90 -- 47% 18%

Extruding CPE/mixing CPE: MDR C 130[degrees]C, 1[degrees] arc
 ts0.4 (min.) 7 41 35
 ts1 (min.) 7 48 44.6
 ts2 (min.) 11.7 55 58.6

Table 4--Vistalon 2504
injection molded brake
cup formulation

Vistalon 2504 100
Zinc oxide 5
AgeRite resin D 1.5
N-550 carbon black 45
DC40KE 10
 (control)

Table 5--curing EPDM with DC40P-SP2 at
177[degrees]C: 50% increase in ts2

Crosslinking Vistalon 2504 EPDM. Cure [RPA: 350[degrees]F
(177[degrees]C), 1[degrees] arc, 100 cpm]

 10 phr 11.5 phr
 DC40KE DC40P-SP2

 [M.sub.H] (dN-m) 67.32 66.16
 [M.sub.L] (dN-m) 2.18 1.78
 [M.sub.H] - [M.sub.L] (dN-m) 65.14 64.38
 ts0.4 (min.) 0.29 0.48
 ts1 (min.) 0.33 0.52
% increase in ts1 -- 58%
 ts2 (min.) 0.38 0.57
% increase in ts2 -- 50%
 tc50 (min.) 1.57 1.77
 tc90 (min.) 4.71 4.72

Table 6--mixing EPDM with DC40P-SP2 at
138 [degrees] C: 204% increase in ts2

Vistalon 2504 EPDM compounds at 138 [degrees] C
RPA scorch: 280[degrees]F (138[degrees]C),
1[degrees] arc, 100 cpm

 10 phr 11.5 phr
 DC40KE DC40P-SP2

 [M.sub.L] (dN-m) 3.22 3.05
 ts1 (min.) 4.61 18.70
% increase in ts1 -- 306%
 ts2 (min.) 7.00 21.26
% increase in ts2 -- 204%

Table 7--curing EPDM with F40P-SP2 at
177 [degrees] C: 43% increase in ts2

Crosslinking Vistalon 2504 EPDM
Cure [RPA: 350[degrees]F (177C), 1[degrees] arc, 100 cpm]

 6.26 phr 6.26 phr 7.20 phr
 F40KE F40M-SP F40P-SP2

 [M.sub.H] (dN-m) 69.20 67.13 71.17
 [M.sub.L] (dN-m) 2.20 2.00 2.00
% decrease in [M.sub.L] -- 10% 10%
 [M.sub.H] - [M.sub.L] (dN-m) 67.00 65.13 69.17
 ts0.4 (min.) 0.34 0.41 0.56
 ts1 (min.) 0.41 0.48 0.63
% increase in ts1 -- 17% 54%
 ts2 (min.) 0.49 0.57 0.71
% increase in ts2 -- 15% 43%
 tc50 (min.) 2.96 3.03 3.14
 tc90 (min.) 9.31 9.42 9.33

Table 8--mixing EPDM with F40P-SP2 at
138[degrees]C: 202% increase in ts1

Using F40M-SP and F40P-SP2 to improve the
compounding of Vistalon 2504 EPDM formulations
[RPA scorch: 280[degrees]F (138[degrees]C),
1[degrees] arc, 100 cpm]

 6.26 phr 6.26 phr 7.20 phr
 F-40KE F40M-SP F40P-SP2

 [M.sub.L] (dN-m) 3.44 3.37 3.39
 ts0.4 (min.) 5.64 11.11 23.70
 ts0.6 (min.) 6.87 12.38 25.07
 ts1 (min.) 9.08 14.64 27.46
% increase in ts1 -- 61% 202%
 ts2 (min.) 14.19 19.85 32.64
% increase in ts2 -- 40% 130%

Table 9--mixing and curing an EVA-EOM
shoe sole compound with F40P-SP2

Evatane EVA (18% vinyl acetate) 80
Engage (EOM) 20
Stearic acid 0.6
Zinc oxide 2.0
Silica 7.0
Calcium carbonate 5.0
Azodicarbonamide 2.3
Polyethylene wax 1.1
Run number 1 2 3
F40KE 1.5 -- --
F40P-SP2 -- 1.5 1.0
Triallyl cyanurate -- -- 0.2
Cure and scorch time of EVA in an RPA at 175[degrees]C
 [M.sub.H] (dN-m) @ 175[degrees]C 10.8 10.8 11.1
 tc90 (min.) @ 175[degrees]C 8.24 8.25 6.76
% decrease in tc90 @ 175[degrees]C -- -- 18%
 ts2 (min.) @ 175[degrees]C 0.82 1.04 1.09
 % increase in ts2 @ 175[degrees]C -- 27% 34%
Scorch time of EVA in a Mooney viscometer at 130[degrees]C
t5 Mooney scorch (minutes) 22.1 56.2 66.6
% increase in t5 scorch @ 130[degrees]C -- 155% 202%

Table 10--mixing and curing a Zetpol 2010
HNBR with DC40P-SP2

DC40KE 8.0 --
DC40P-SP2 -- 9.4
MDR at 350[degrees]F (177
[degrees]C), 1[degrees] arc, 100 cpm
 [M.sub.H] (dN-m) 15.03 15.19
 [M.sub.L] (dN-m) 0.72 0.59
% decrease in ML -- 18%
 [M.sub.H] - [M.sub.L] (dN-m) 14.31 14.60
 tc 90 (min.) 4.24 4.30
 ts 1 (min.) 0.70 0.84
% increase in ts1 -- 20%
MDR at 300[degrees]F (149
[degrees]C), 1[degrees] arc, 100 cpm
 ts1 (min.) 5.26 8.92
 % change in ts1 -- 70%

Table 11--mixing and curing a Zetpol 2010
HNBR with F40P-SP2 (ref. 11)

F40KE 8.0 --
F40P-SP2 -- 9.2
MDR at 338[degrees]F (170
[degrees]C), 0.5[degrees] arc, 100 cpm
 [M.sub.H] (dN-m) 20.9 21.5
 [M.sub.L] (dN-m) 1.6 1.5
 [M.sub.H] - [M.sub.L] (dN-m) 19.3 20.0
 tc 90 (min.) 10.4 10.5
 ts 2 (min) 1.30 1.60
% increase in ts2 -- 23%
Compression set: method B, buttons
70 hrs. @ 150[degrees]C 22.8% 21.7%
t5 Mooney scorch (minutes)
t5 (minutes) @ 135[degrees]C 16.20 >30
% change in t5 -- >85%
 t5 (minutes) @ 145[degrees]C 7.30 12.30
% change in t5 -- 68%

Figure 1--ts2 scorch time @ 130[degrees]-145[degrees]C:
Vamac DHC using F4OP-SP2 or DC4OP-SP2

ts2 scorch time (minutes)

135[degrees]C 19.37
145[degrees]C 6.75
F40 51.07
F40P-SP2 17.27

130[degrees]C 15.66
140[degrees]C 5.42
DC40 38.92
DC40P-SP2 13.06

Note: Table made from bar graph.

Figure 2--effect of F40P-SP2 and coagent
on CPE tc90 cure time (minutes)

Effect of peroxide and coagent on Tc90 of
CPE @ 180[degrees]

6 phr F40KE
+ 2 phr TMPTMA 4.3

6 phr F40P-SP2
+ 1.5 phr TAC 3.6

6 phr F40P-SP2 +
3 phr HVA2 2.3

Note: Table made from bar graph.
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Copyright 2007, Gale Group. All rights reserved. Gale Group is a Thomson Corporation Company.

 
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Author:Palys, Leonard H.
Publication:Rubber World
Date:Jun 1, 2007
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