Peroxide masterbatch

Abstract

Peroxide masterbatch comprising: 15-55 wt % of one or more organic peroxides, 15-45 wt % of one or more copolymers of at least two different monomers, the first monomer being ethylene or propylene, the second monomer being a vinyl monomer comprising at least four carbon atoms and optionally heteroatoms, 6-70 wt % of at least two filler typesfiller type 1 and filler type 2each having a different BET surface area: (i) filler type 1 being present in the masterbatch in a concentration of 3-30 wt % and having a BET surface area of more than 100 m.sup.2/g; (ii) filler type 2 being present in the masterbatch in a concentration of 3-40 wt % and having a BET surface area of 100 m.sup.2/g or less; wherein the masterbatch has the form of extrudates.

Claims

1. Peroxide masterbatch comprising: 15-55 wt % of one or more organic peroxides, 15-45 wt % of one or more copolymers of at least two different monomers, the first monomer being ethylene or propylene, the second monomer being a vinyl monomer comprising at least four carbon atoms and optionally heteroatoms, 6-70 wt % of at least two filler typesfiller type 1 and filler type 2each having a different BET surface area: (i) filler type 1 being present in the masterbatch in a concentration of 3-30 wt % and having a BET surface area of more than 100 m.sup.2/g; (ii) filler type 2 being present in the masterbatch in a concentration of 3-40 wt % and having a BET surface area of 100 m.sup.2/g or less; wherein the masterbatch has the form of extrudates.

2. Peroxide masterbatch according to claim 1 comprising 30-52 wt % of one or more peroxides.

3. Peroxide masterbatch according to claim 1 comprising an organic peroxide is-selected from the group consisting of dicumyl peroxide, di(tert-butylperoxyisopropyl)benzene, 1,1-di(tert-butylperoxy)-3,3,5-tri-methylcyclohexane, butyl-4,4-di(tert-butylperoxy)valerate, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, and tert-butyl peroxy-3,5,5-trimethylhexanoate.

4. Peroxide masterbatch according to claim 1 comprising a copolymer i& selected from ethylene-vinyl acetate copolymers, copolymers of (i) ethylene or propylene and (ii) 1-butene, 1-hexene, and/or 1-octene, copolymers of ethylene and acrylates, styrene ethylene butylene hydrogenated copolymers, and styrene ethylene propylene hydrogenated copolymers.

5. Peroxide masterbatch according to claim 4 wherein the copolymer comprises a copolymer of (i) ethylene or propylene and (ii) 1-butene and/or 1-octene.

6. Peroxide masterbatch according to claim 4 wherein the copolymer is an ethylene-vinyl acetate copolymer.

7. Peroxide masterbatch according to claim 1 comprising 3-15 wt % of filler type 1 and 10-30 wt % of filler type 2.

8. Peroxide masterbatch according to claim 1 wherein filler type 1 has a BET surface area of more than 150 m.sup.2/g.

9. Peroxide masterbatch according to claim 1 wherein filler type 1 is selected from carbon black, silica, and combinations thereof.

10. Peroxide masterbatch according to claim 1 wherein filler type 2 has a BET surface area below 10 m.sup.2/g.

11. Peroxide masterbatch according to claim 1 wherein filler type 2 is selected from calcium carbonate, barium sulphate, clay, and combinations thereof.

12. Process for the preparation of a peroxide masterbatch of claim 1 wherein the one or more organic peroxides, granules or pellets of the one or more copolymers, and the at least two filler types are added to an extruder and extruded at a temperature in the range 50-95 C.

13. Process according to claim 11 wherein the extrusion is conducted at a temperature in the range 70-85 C.

14. Process for crosslinking of an elastomer comprising the step of dispersing the peroxide masterbatch according to claim 1 in the elastomer to be crosslinked.

15. The process according to claim 4, wherein the elastomer comprises EPM.

16. The process according to claim 4, wherein the elastomer comprises EPDM.

Description

EXAMPLES

Example 1

(1) Two masterbatches according to the invention were prepared. The first masterbatch contained dicumyl peroxide (Perkadox BC, ex-AkzoNobel); the second masterbatch contained di(tert-butylperoxyisopropyl)benzene (Perkadox 14S, ex-AkzoNobel).

(2) The copolymer used was a POE copolymer of ethylene and 1-octene (Engage 8180 ex-Dow). Filler type 1 was silica with a BET surface area of 125 m.sup.2/g. Filler type 2 was CaCO.sub.3 with a BET surface area of 5 m.sup.2/g.

(3) These masterbatches were prepared by extrusion, using a barrel temperature of 75 C. and a screw speed of 100 rpm. After extrusion, the produced string was cooled and chopped to granules.

(4) A similar, but comparative masterbatch was prepared on a two-roll mill. The temperature of the front roll ranged from 60 C. at the start to 50 C. during production. The temperature of the back roll ranged from 75 C. at the start to 70 C. during production. The nip setting was 1 mm, leading to 4 mm thick sheets after cooling. After cooling and resting for one week, sheets were cut into 1084 mm pieces.

(5) The resulting masterbatches were tested for their dispersion behaviour in EPDM. This behaviour was compared with that of two commercial AkzoNobel masterbatches containing the same peroxides, but based on EPM and being prepared using a two roll mill instead of an extruder: Perkadox BC-40 MB-GR and Perkadox 14-40 MB-GR-S.

(6) The dispersion behaviour was tested by mixing, on a two-roll mill at 60 C., 100 weight parts of EPDM (Dutral 4044, ex-Versalis), 70 parts by weight carbon black N-550 and 70 parts by weight of carbon black N-772 (both ex-Cabot), 70 parts by weight processing oil (Catanex D 579, ex-Shell), and 10 parts by weight of the masterbatches.

(7) The carbon/EPDM system was black coloured; the masterbatch was white. Hence, the dispersion of the masterbatch in the rubber could be observed by visual inspection. The mixing time required to reach visual full dispersion of the masterbatch in the EPDM matrix is listed in Table 1 and shows that the masterbatches according to the present invention disperse much faster in EPDM than the masterbatches prepared on a two roll mill.

(8) TABLE-US-00001 TABLE 1 Perkadox Perkadox BC-40MB- 14-40MB- Inv. 1 Inv. 2 Comp. 1 GR GR-S Mixing Ex- Ex- Two roll Two roll Two roll technology truder truder mill mill mill Perkadox BC 40 40 40 Perkadox 14S 40 40 Calcium 20 20 20 20 20 carbonate Silica 10 10 10 10 10 POE 30 30 30 EPM 30 30 Mixing time 1:53 1:47 2:00 2:55 3:13 (min:sec)

(9) The crosslink behaviour of the masterbatches was tested in a rheometer using the materials, amounts, and conditions listed in Table 2. It shows that the crosslink density and mechanical properties obtained by using the masterbatches according to invention are comparable to those obtained using the commercial masterbatches.

(10) TABLE-US-00002 TABLE 2 EPDM 100 100 100 100 Carbon Black (N-550) 70 70 70 70 Carbon black (N-772) 70 70 70 70 Sunpar 550 oil 50 50 50 50 Perkadox BC inventive 6.1 masterbatch Perkadox 14 inventive 3.8 masterbatch Perkadox BC-40-MB-GR 6.1 Perkadox 14-40-MB-GR 3.8 Rheometer C. 170 175 170 175 ts2 (min) 0.8 0.9 0.8 0.9 t5 (min) 0.4 0.4 0.4 0.4 t50 (min) 1.9 2.2 1.9 2.2 t90 (min) 6.4 7.2 6.0 7.2 ML (Nm) 0.2 0.3 0.3 0.3 MH (Nm) 1.3 1.3 1.3 1.3 delta S (Nm) 1.1 1.0 1.0 1.1 Tensile Strength (N/mm.sup.2) 12.7 12.3 12.1 12.3 Elongation at break (%) 326 345 321 344 M50 (N/mm.sup.2) 2.1 2.1 2.3 2.2 M100 (N/mm.sup.2) 4.2 4.2 4.6 4.3 M200 (N/mm.sup.2) 9.3 9.2 9.5 9.2 M300 (N/mm.sup.2) 12.5 11.9 12.0 11.8 IRHD Hardness 74.2 75.5 73.4 75.3 Crescent Tear 34.7 35.7 35.7 37.9 strength (kN/m)

Example 2

(11) Example 1 was repeated, except for using different copolymers: Engage HM7387 ex-Dow (a POE copolymer of ethylene and 1-butene) Elvax 360A ex-DuPont (an ethylene vinyl acetate copolymer).

(12) All masterbatches of this example were prepared in an extruder.

(13) The results are displayed in Table 3.

(14) TABLE-US-00003 TABLE 3 Comp. Inv. 3 Comp. 2 Comp. 3 Inv. 4 Inv. 5 4 Perkadox BC 40 40 60 40 40 Perkadox 14S 40 Calcium 20 20 10 10 carbonate Silica 10 20 20 POE 30 40 40 EVA 30 30 60 Observations Chopping Chopping Very difficult difficult wet, poor mixing Mixing time 1:10 1:15 1:15 0:45 0:30 2:40 (min:sec)

(15) Experiments Inv. 3 and Comp. 2 and 3 and Experiments Inv. 4 and Comp. 4 show that the fillers, and especially the type 1 fillers are preferred for obtaining suitable extrudates.