CURABLE COMPOSITION COMPRISING AN ETHYLENE POLYMER, A MONOPEROXYCARBONATE AND A t-ALKYL HYDROPEROXIDE

Abstract

The present invention pertains to a curable composition comprising (a) at least one ethylene polymer, (b) less than 2 parts by weight of at least one monoperoxycarbonate for 100 parts by weight of constituent (a), (c) from 0.4 to less than 4 part by weight of at least one t-alkyl hydroperoxide for 100 parts by weight of constituent (b). It is also directed to a method for preventing scorching of a curable composition comprising an ethylene polymer, by adding a specific amount of t-alkyl hydroperoxide thereto and to a method for manufacturing a scorch-protected material.

Claims

1. A curable composition comprising: (a) at least one ethylene polymer, (b) less than 2 parts by weight of at least one monoperoxycarbonate for 100 parts by weight of constituent (a), (c) from 0.4 to less than 4 parts by weight of at least one t-alkyl hydroperoxide for 100 parts by weight of constituent (b).

2. The composition of claim 1, wherein the ethylene polymer is an ethylene/vinyl acetate copolymer.

3. The composition of claim 1, wherein the ethylene polymer is a polyolefin elastomer.

4. The composition of claim 1, wherein the monoperoxycarbonate is an OO-t-alkyl-O-alkyl monoperoxycarbonate.

5. The composition according to claim 4, wherein the OO-t-alkyl-O-alkyl monoperoxycarbonate is selected from the group consisting of: OO-t-butyl-O-2-ethylhexyl-monoperoxycarbonate (TBEC), OO-t-butyl-O-2-isopropyl-monoperoxycarbonate (TBIC), OO-t-amyl-O-2-ethylhexyl-monoperoxycarbonate (TAEC), OO-t-amyl-O-2-isopropyl-monoperoxycarbonate (TAIC) and mixtures thereof.

6. The composition of claim 1, wherein the monoperoxycarbonate is from 0.1 to less than 2 parts by weight of constituent (a).

7. The composition of claim 1, wherein the t-alkyl hydroperoxide is selected from the group consisting of: t-butyl hydroperoxide (TBHP), t-amyl hydroperoxide (TAHP), t-hexyl hydroperoxide (THHP), 1,1,3,3-tetramethylbutyl hydroperoxide (TOHP), paramenthane hydroperoxide (PMHP), 2,5-dimethyl-2,5-di-hydroperoxide (2,5-2,5) and mixtures thereof.

8. The composition of claim 1, comprising from 0.5 to 3.5 parts by weight of constituent (c) for 100 parts by weight of constituent (b).

9. The composition of claim 1, further comprising one co-agent selected in the group consisting of: triallyl cyanurate, triallyl isocyanurate, N,N-m-phenylenedimaleimide, triallyl trimellitate, trimethylolpropane triacrylate and trimethylolpropane trimethacrylate.

10. (canceled)

11. A method for preventing scorching of a curable composition comprising (a) at least one ethylene polymer, and (b) at least one monoperoxycarbonate, comprising the step of adding at least one t-alkyl hydroperoxide into the composition, in an amount of from 0.4 to less than 4 parts by weight for 100 parts by weight of constituent (b).

12. A method for manufacturing a scorch-protected material comprising an ethylene polymer, said method comprising a step a) of curing a composition comprising: (a) at least one ethylene polymer, (b) less than 2 parts by weight of at least one monoperoxycarbonate for 100 parts by weight of constituent (a), and (c) from 0.4 to less than 4 parts by weight of at least one t-alkyl hydroperoxide for 100 parts by weight of constituent (b).

13. The method according to claim 12, further comprising a previous and/or simultaneous step a), wherein step a) is selected from the group consisting of: molding, extruding and injecting the composition of claim 1.

14. The method according to claim 13, wherein step a) is carried out at a temperature from 80 to 150 C.

15. A scorch-protected material comprising an ethylene polymer obtained by the method of claim 12.

16. A photovoltaic module comprising a scorch-protected material comprising an ethylene polymer obtained by the method of claim 12.

Description

EXAMPLES

Example 1: Scorch Protection Effect

[0086] Compositions according to this invention were prepared by mixing an ethylene/vinyl acetate (EVA) copolymer (Cosmothene EVA KA-40 containing 28% VA, supplied by SUMITOMO) with OO-t-amyl-O-2-ethylhexyl-monoperoxycarbonate (Luperox TAEC available from Arkema) and t-amyl hydroperoxide (Luperox TAHP available from Arkema) in a Haake internal mixer at 35 C. for 12 minutes, using a stirring rate of 50 rpm/min. The polymeric mixture was then passed through an open mill set at 60 C. to produce sheets of about 2 mm thickness.

[0087] Samples of about 2 to 3 g of the above compositions were deposited in plate on a moving die rheometer (MDR) supplied by GOTECH, which is able to measure the cure properties of the samples and includes a software for analyzing the results. Each of the samples is placed in a temperature-controlled cavity between two dies, the lower of which oscillates to apply a cyclic stress or strain to the sample while the upper die is connected to a torque sensor to measure the torque response of the sample at the deformation. The stiffness is recorded continuously as a function of time. The stiffness of the sample increases as vulcanization proceeds.

[0088] This apparatus is able to provide, inter alia, calculated values of ML (minimum torque), MH (maximum torque), tc10 (time to 10% state of cure) and tc90 (time to 90% state of cure) as defined by International Standards (ASTM D5289 and ISO 6502).

[0089] The MDR was operated at 115 and 145 C. with an oscillation amplitude (deformation degree) of 0.5 applied to the sample for 30 min. The scorch time was defined as the time necessary to reach 10% of the total cure, i.e. tc10.

[0090] This experiment was conducted on the following samples, wherein the amounts of monoperoxycarbonate was indicated as parts per hundred parts of EVA resin (phr) and the amounts of TAHP as parts by weight for 100 parts by weight of monoperoxycarbonate:

TABLE-US-00001 TABLE 1 TAHP/ MH-ML TAEC MH (dN .Math. m) (dN .Math. m) tc10 (m:s) tc90 (m:s) TAEC (wt/wt) at 115 C. at 145 C. at 145 C. at 145 C. 0.5 phr 0.02% 1.27 1.8 1:03 8:52 0.5 phr 0.4% 1.17 1.82 1:05 8:58 0.5 phr 0.98% 1.15 1.86 1:07 9:21 0.5 phr 1.38% 1.06 1.82 1:09 9:27 0.5 phr 2% 0.63 1.8 1:17 9:31 0.5 phr 4% 0.35 1.74 1:43 9:43 0.5 phr 5% 0.32 1.60 2:31 10:58 0.7 phr 0.02% 1.45 2.02 0:56 9:50 0.7 phr 0.2% 1.41 1.99 1:00 10:00 0.7 phr 0.98% 1.31 1.96 1:05 10:10 0.7 phr 2% 1 1.96 1:12 10:18 0.7 phr 4% 0.37 1.91 1:40 10:42 1 phr 0.02% 1.68 2.22 0:55 10:48 1 phr 0.2% 1.63 2.24 0:56 10:56 1 phr 0.98% 1.53 2.19 1:00 10:48 1 phr 2% 1.24 2.21 1:09 11:24 1 phr 4% 0.43 2.13 1:33 11:45 1 phr 5% 0.42 1.85 1:45 13:30

[0091] From this table, it can be seen that TAHP acts as a scorch-protection agent since scorch time (tc10) increases with the amount of TAHP. When the amount of TAHP is below 0.4 wt % relative to TAEC, the crosslinking starts even at 115 C. (see MH values), which is not desired. However, there is a dramatic increase of the crosslinking time (tc90), and thus a lower crosslinking rate, when the latter reaches 4 wt % relative to TAEC and also a lower crosslinking density (MH). At values of TAHP below 4 wt % relative to TAEC, scorch is effectively prevented while maintaining a high crosslinking rate (tc90) and a good crosslinking density (MH-ML).

Example 2

[0092] The experiment was conducted in the same conditions as for example 1, except that a mixture of 20% of O,O-tert-butyl-O-(2-ethylhexyl)monoperoxycarbonate (TBEC) and 80% of O,O-tert-amyl-O-(2-ethylhexyl) monoperoxycarbonate (TAEC) was used instead of TAEC alone. The results are shown in the table 2 below:

TABLE-US-00002 TABLE 2 TAHP/ (TAEC + MH-ML tc10 TAEC + TBEC) MH (dN-m) (dN-m) at (m:s) at tc90 (m:s) at TBEC (wt/wt) at 115) C. 145 C. 145 C. 145 C. 0.5 phr 0.2% 1.35 1.87 0:58 9:57 0.5 phr 0.6% 1.15 1.88 1:08 10:06 0.5 phr 1% 0.96 1.89 1:14 10:19 0.5 phr 2% 0.56 1.88 1:22 10:18 0.5 phr 4% 0.36 1.84 1:48 11:06 0.7 phr 0% 1.65 2.1 0:58 10:31 0.7 phr 0.2% 1.6 2.03 1:04 10:42 0.7 phr 0.6% 1.38 1.99 1:07 10:55 0.7 phr 1% 1.07 1.98 1:12 11:12 0.7 phr 2% 0.65 1.97 1:21 11:26 0.7 phr 4% 0.41 1.95 1:44 12:14 1 phr 0% 1.6 2.28 0:55 11:36 1 phr 0.2% 1.58 2.26 0:58 11:45 1 phr 0.6% 1.37 2.25 1:01 11:57 1 phr 1% 1.24 2.24 1:05 12:12 1 phr 2% 0.81 2.22 1:16 12:25 1 phr 4% 0.38 2.19 1:41 13:10

[0093] As for the previous example, there is a dramatic increase of the crosslinking time (tc90), when the latter reaches 4 wt % relative to TAEC+TBEC.

Example 3

[0094] The experiment was conducted in the same conditions than for example 1, except that a mixture of 50% of O,O-tert-butyl-O-(2-ethylhexyl)monoperoxycarbonate (TBEC) and 50% of O,O-tert-amyl-O-(2-ethylhexyl) monoperoxycarbonate (TAEC) was used instead of TAEC alone. The results are shown in the table 3 below:

TABLE-US-00003 TABLE 3 TAHP/ (TAEC + MH MH-ML tc90 TAEC + TBEC) (dN .Math. m) (dN .Math. m) at tc10 (m:s) at (m:s) at TBEC (wt/wt) at 115 C. 145 C. 145 C. 145 C. 0.5 phr 0% 1.30 1.83 0:58 9:16 0.5 phr 1% 1.02 1.87 1:10 9:36 0.5 phr 4% 0.36 1.81 1:40 10:21 0.7 phr 0% 1.45 1.99 0:58 9:55 0.7 phr 0.6% 1.29 1.97 1:03 10:03 0.7 phr 1% 1.19 1.92 1:15 10:17 0.7 phr 4% 0.36 1.88 1:42 10:47 1 phr 0% 1.65 2.28 0:58 11:12 1 phr 0.6% 1.49 2.23 1:02 11:18 1 phr 1% 1.4 2.22 1:08 11:21 1 phr 4% 0.41 2.13 1:33 11:56

[0095] As for the previous examples, there is a dramatic increase of the crosslinking time (tc90), when the latter reaches 4 wt % relative to TAEC+TBEC.

Example 4

[0096] The experiment was conducted in the same conditions than for example 1, except that Lup@TBHP (tert-butyl hydroperoxide) was used instead of TAHP. The results are shown in the table 4 below:

TABLE-US-00004 TABLE 4 TBHP/ MH-ML TAEC MH (dN .Math. m) (dN .Math. m) tc10 (m:s) tc90 (m:s) TAEC (wt/wt) at 115 C. at 145 C. at 145 C. at 145 C. 0.5 phr 0.02% 1.25 1.79 1:02 8:50 0.5 phr 0.4% 1.18 1.83 1:06 8:55 0.5 phr 1% 1.17 1.86 1:07 9:21 0.5 phr 2% 0.62 1.81 1:19 9:35 0.5 phr 4% 0.37 1.75 1:45 9:59 0.5 phr 5% 0.31 1.59 2:35 10:59 0.7 phr 0.02% 1.44 2.01 0:57 9:52 0.7 phr 0.2% 1.40 1.97 1:02 10:05 0.7 phr 1% 1.30 1.96 1:06 10:10 0.7 phr 2% 1.02 1.95 1:15 10:20 0.7 phr 4% 0.36 1.93 1:45 10:45 1 phr 0.02% 1.65 2.21 0:55 10:45 1 phr 0.2% 1.62 2.25 0:57 10:58 1 phr 1% 1.53 2.18 1:02 10:46 1 phr 2% 1.25 2.20 1:08 11:25 1 phr 4% 0.42 2.14 1:32 11:42 1 phr 5% 0.40 1.82 1:43 13:28

[0097] As for the previous examples, there is a dramatic increase of the crosslinking time (tc90), when the latter reaches 4 wt % relative to TAEC pure.

Example 5

[0098] The experiment was conducted in the same conditions than for example 4, except that a mixture of 20% of O,O-tert-butyl-O-(2-ethylhexyl)monoperoxycarbonate (TBEC) and 80% of O,O-tert-amyl-O-(2-ethylhexyl) monoperoxycarbonate (TAEC) was used instead of TAEC alone. The results are shown in the table 5 below:

TABLE-US-00005 TABLE 5 TBHP/ (TAEC + MH-ML tc90 TAEC + TBEC) MH (dN-m) (dN-m) at tc10 (m:s) at (m:s) at TBEC (wt/wt) at 115) C. 145 C. 145 C. 145 C. 0.5 phr 0.2% 1.32 1.89 0:57 9:56 0.5 phr 0.6% 1.16 1.88 1:05 10:05 0.5 phr 1% 0.95 1.88 1:12 10:12 0.5 phr 2% 0.55 1.88 1:23 10:15 0.5 phr 4% 0.37 1.85 1:47 11:08 0.7 phr 0% 1.62 2.1 0:58 10:31 0.7 phr 0.2% 1.61 2.01 1:02 10:40 0.7 phr 0.6% 1.42 1.99 1:09 10:54 0.7 phr 1% 1.12 1.98 1:15 11:13 0.7 phr 2% 0.7 1.98 1:20 11:25 0.7 phr 4% 0.45 1.94 1:41 12:12 1 phr 0% 1.61 2.27 0:54 11:36 1 phr 0.2% 1.59 2.25 0:59 11:47 1 phr 0.6% 1.38 2.26 1:02 11:55 1 phr 1% 1.26 2.23 1:04 12:13 1 phr 2% 0.85 2.23 1:15 12:24 1 phr 4% 0.40 2.20 1:42 13:15

[0099] As for the previous examples, there is a dramatic increase of the crosslinking time (tc90), when the latter reaches 4 wt % relative to TAEC+TBEC.

Example 6

[0100] The experiment was conducted in the same conditions than for example 4, except that a mixture of 50% of O,O-tert-butyl-O-(2-ethylhexyl)monoperoxycarbonate (TBEC) and 50% of O,O-tert-amyl-O-(2-ethylhexyl) monoperoxycarbonate (TAEC) was used instead of TAEC alone. The results are shown in the table 6 below:

TABLE-US-00006 TABLE 6 TBHP/ (TAEC + MH MH-ML tc90 TAEC + TBEC) (dN .Math. m) (dN .Math. m) tc10 (m:s) at (m:s) at TBEC (wt/wt) at 115 C. at 145 C. 145 C. 145 C. 0.5 phr 0% 1.25 1.85 0:55 9:15 0.5 phr 1% 1.05 1.82 1:12 9:38 0.5 phr 4% 0.35 1.78 1:41 10:22 0.7 phr 0% 1.41 1.98 0:57 9:51 0.7 phr 0.6% 1.32 1.96 1:05 10:00 0.7 phr 1% 1.21 1.93 1:16 10:16 0.7 phr 4% 0.39 1.87 1:45 10:52 1 phr 0% 1.66 2.27 0:57 11:10 1 phr 0.6% 1.48 2.24 1:02 11:18 1 phr 1% 1.37 2.23 1:09 11:20 1 phr 4% 0.42 2.10 1:35 11:59

[0101] As for the previous examples, there is a dramatic increase of the crosslinking time (tc90), when the latter reaches 4 wt % relative to TAEC+TBEC.

Example 7

[0102] The experiment was conducted in the same conditions as for example 1, except that OO-t-amyl-O-2-isopropyl-monoperoxycarbonate (TRIC) was used instead of TAEC. The results are shown in the table 7 below:

TABLE-US-00007 TABLE 7 TAHP/ MH-ML tc90 TAIC MH (dN .Math. m) (dN .Math. m) tc10 (m:s) (m:s) at TAIC (wt/wt) at 115 C. at 145 C. at 145 C. 145 C. 0.5 phr 0 1.2 1.79 00:50 07:45 0.5 phr 0.65% 1.1 1.76 01:00 08:05 0.5 phr 1% 1.05 1.7 01:10 08:20

[0103] From this table, it can be seen that with the addition of at least 0.4% wt of TAHP relative to TAEC, scorch is effectively prevented while maintaining a high crosslinking rate (tc90) and a good crosslinking density (MH-ML).

Example 8

[0104] The experiment was conducted in the same conditions as for example 1, except that a mixture of 60% of O,O-t-amyl-O-2-isopropyl-monoperoxycarbonate (TAIC) and 40% of O,O-tert-amyl-O-(2-ethylhexyl) monoperoxycarbonate (TAEC) was used instead of TAEC alone. The results are shown in the table 8 below:

TABLE-US-00008 TABLE 8 TAHP/ 60% TAIC + MH MH-ML tc10 tc90 TAIC + TAEC (dN .Math. m) at (dN .Math. m) at (m:s) at (m:s) at 40% TAEC (wt/wt) 115 C. 145 C. 145 C. 145 C. 0.5 phr 0 1.18 1.76 00:58 08:10 0.5 phr 0.70% 1.1 1.72 01:10 08:32 0.5 phr 1% 1 1.65 01:20 08:40

[0105] From this table, it can be seen that with the addition of at least 0.4% wt of TAHP relative to TAIC, scorch is effectively prevented while maintaining a high crosslinking rate (tc90) and a good crosslinking density (MH-ML).

Example 9

[0106] The experiment was conducted in the same conditions as for example 1, except that polyolefin elastomer (KJ640T 27255C manufactured by JAPAN POLYETHYLENE CORPORATION) was used instead of EVA. The results are shown in the table 9 below:

TABLE-US-00009 TABLE 9 TAHP/ MH-ML tc90 TAEC MH (dN .Math. m) (dN .Math. m) at tc10 (m:s) (m:s) at TAEC (wt/wt) at 115 C. 145 C. at 145 C. 145 C. 0.5 phr 0.02% 0.3 1.35 02:00 17:00 0.5 phr 0.40% 0.28 1.31 02:15 17:10 0.5 phr 0.98% 0.26 1.28 02:25 17:20

[0107] From this table, it can be seen that with the addition of at least 0.4% wt of TAHP relative to TAEC, scorch is effectively prevented while maintaining a high crosslinking rate (tc90) and a good crosslinking density (MH-ML).

Example 10

[0108] The experiment was conducted in the same conditions as for example 9, except that O,O-tert-butyl-O-(2-ethylhexyl)monoperoxycarbonate (TBEC) was used instead of O,O-tert-amyl-O-(2-ethylhexyl) monoperoxycarbonate (TAEC). The results are shown in the table 10 below:

TABLE-US-00010 TABLE 10 TBHP/ MH TBEC (dN .Math. m) MH-ML (dN .Math. m) tc10 (m:s) tc90 (m:s) TBEC (wt/wt) at 115 C. at 145 C. at 145 C. at 145 C. 0.5 phr 0.20% 0.29 1.1 03:00 22:00 0.5 phr 0.60% 0.26 1 03:11 22:13 0.5 phr 1% 0.24 0.95 03:18 22:25

[0109] From this table, it can be seen that with the addition of at least 0.4% wt of TBHP relative to TBEC, scorch is effectively prevented while maintaining a high crosslinking rate (tc90) and a good crosslinking density (MH-ML).

Example 11

[0110] The experiment was conducted in the same conditions as for example 9, except that O,O-t-amyl-O-2-isopropyl-monoperoxycarbonate (TAIC) was used instead of 0,0-tert-amyl-O-(2-ethylhexyl) monoperoxycarbonate (TAEC). The results are shown in the table 11 below:

TABLE-US-00011 TABLE 11 MH-ML tc90 TAHP/TAIC MH (dN .Math. m) (dN .Math. m) tc10 (m:s) (m:s) at TAIC (wt/wt) at 115 C. at 145 C. at 145 C. 145 C. 0.5 phr 0 0.38 1.73 01:50 14:20 0.5 phr 0.65% 0.35 1.68 02:00 14:27 0.5 phr 1% 0.31 1.62 02:12 14:36

[0111] From this table, it can be seen that with the addition of at least 0.4% wt of TAHP relative to TAIC, scorch is effectively prevented while maintaining a high crosslinking rate (tc90) and a good crosslinking density (MH-ML).

Example 12

[0112] The experiment was conducted in the same conditions as for example 9, except that O,O-t-butyl-O-2-isopropyl-monoperoxycarbonate (TBIC) was used instead of 0,0-tert-amyl-O-(2-ethylhexyl) monoperoxycarbonate (TAEC). The results are shown in the table 12 below:

TABLE-US-00012 TABLE 12 TBHP/ MH-ML tc90 TBIC MH (dN .Math. m) (dN .Math. m) at tc10 (m:s) (m:s) at TBIC (wt/wt) at 115 C. 145 C. at 145 C. 145 C. 0.5 phr 0 0.31 1.66 02:45 20:00 0.5 phr 0.70% 0.28 1.6 02:58 20:10 0.5 phr 1% 0.26 1.57 03:06 20:15

[0113] From this table, it can be seen that with the addition of at least 0.4% wt of TBHP relative to TBIC, scorch is effectively prevented while maintaining a high crosslinking rate (tc90) and a good crosslinking density (MH-ML).