CROSSLINKING ACCELERATORES FOR SILANE-GROUP CONTAINING POLYMER COMPOSITIONS

Abstract

The present invention relates to a cross-linkable, grafted or non-grafted polymer composition comprising a cross-linkable copolymer containing hydrolysable silane groups. The invention further relates to a crosslinked polymer composition obtained by cross-linking the cross-linkable copolymer containing hydrolysable silane groups and an article comprising the same. The present invention also relates to the use of one or more cross-linking accelerators for accelerating the crosslinking of a cross-linkable copolymer containing hydrolysable silane groups.

Claims

1-13. (canceled)

14. A cross-linkable polymer composition comprising (A1) a cross-linkable, non-grafted copolymer containing hydrolysable silane groups, (B) a condensation catalyst, and (C) a cross-linking accelerator, wherein the cross-linkable, non-grafted copolymer containing hydrolysable silane groups (A) is obtained by copolymerizing one or more olefin monomers with an unsaturated silane compound, wherein the condensation catalyst (B) comprises a metal carboxylate, and wherein the cross-linking accelerator (C) is present in an amount of 6 to 75 wt. % based on the total cross-linkable polymer composition.

15. The cross-linkable polymer composition according to claim 14, wherein the metal of the metal carboxylate is selected from the group consisting of tin, zinc, iron, lead or cobalt.

16. The cross-linkable polymer composition according to claim 14, wherein the condensation catalyst (B) is present in an amount of 0.001 wt. % to 3 wt. % based on the total cross-linkable polymer composition.

17. The cross-linkable polymer composition according to claim 14, wherein the cross-linking accelerator (C) comprises a metal hydroxide, an alkaline metal hydroxide, an alkaline earth metal hydroxide or mixtures thereof.

18. The cross-linkable polymer composition according to claim 14, wherein the cross-linking accelerator (C) comprises Al2(OH)3, Mg(OH)2 or mixtures thereof.

19. The cross-linkable polymer composition according to claim 14, wherein the unsaturated silane compound is one or more selected from the group consisting of vinyl trimethoxysilane, vinyl bismethoxyethoxysilane, vinyl triethoxysilane, vinyl triisopropoxysilane, vinyl tri-n-butoxy silane, gamma-(meth)acryloxypropyltrimethoxysilane, gamma-(meth)acryloxypropyltriethoxysilane and vinyl triacetoxysilane.

20. The cross-linkable polymer composition according to claim 14, wherein the olefin monomer is one or more selected from the group consisting of ethylene, propylene, or butylene.

21. The cross-linkable polymer composition according to claim 14, wherein copolymerizing is carried out in the presence of one or more comonomers, wherein the comonomer is one or more selected from the group consisting of methyl acrylate, ethyl acrylate and butyl acrylate.

22. The cross-linkable polymer composition according to claim 14, wherein the cross-linkable polymer composition comprises a filler, wherein the filler is present in an amount of 0.01 wt. % to 40 wt. % based on the total cross-linkable polymer composition.

23. A cross-linkable polymer composition comprising (A2) a cross-linkable, grafted copolymer containing hydrolysable silane groups, (B) a condensation catalyst, and (C) a cross-linking accelerator, wherein the condensation catalyst (B) comprises a metal carboxylate, and wherein the cross-linking accelerator (C) comprises a metal hydroxide, an alkaline metal hydroxide, an alkaline earth metal hydroxide or mixtures thereof, and wherein the cross-linking accelerator (C) is present in an amount of 6 wt. % to 75 wt. % based on the total cross-linkable polymer composition.

24. Crosslinked polymer composition obtained by cross-linking the cross-linkable polymer composition according to claim 14.

25. Article comprising the cross-linkable polymer composition according to claim 14.

26. Accelerating the crosslinking of a cross-linkable, non-grafted copolymer containing hydrolysable silane groups (A) in the presence of a condensation catalyst(B) with one or more cross-linking accelerators (C) selected from the group consisting of a metal hydroxide, an alkaline metal hydroxide, an alkaline earth metal hydroxide or mixtures thereof, wherein the cross-linkable, non-grafted copolymer containing hydrolysable silane groups (A) is obtained by copolymerizing one or more olefin monomers with an unsaturated silane compound.

Description

EXAMPLES

[0079] 1. Measurement Methods

[0080] a) Melt Flow Rate

[0081] The melt flow rate (MFR.sub.2) is determined according to ISO 1133 and is indicated in g/10 minutes.

[0082] For ethylene-based polymers it is determined with a load of 2.16 kg and at a temperature of 190° C. For propylene-based polymers it is determined with a load of 2.16 kg and at a temperature of 230° C.

[0083] b) Hot Set

[0084] The crosslinking rate of the polymer composition was determined as Hot Set according to IEC 811-2-1-9. Hot set testing was performed on dumbbell samples, prepared from the tape, at 200° C. with 20 N/cm.sup.2, and the elongation of the sample was measured after 15 min, following IEC 811-2-1-9. The tape is prepared as described below.

[0085] 2. Materials

[0086] Polymer A: Copolymer of ethylene and vinyl trimethoxy silane (1.35 wt. %), having a MFR.sub.2 of 1.0 g/10 min. The copolymer is produced in a front feed tubular high pressure reactor at 235 MPa and a peak temperature of 260° C.

[0087] Polymer B: Terpolymer of ethylene, butyl acrylate (10 wt. %) and vinyltrimethoxysilane (1.5 wt. %), the terpolymer having a MFR.sub.2 of 0.5 g/10 min. The terpolymer is produced in a tubular front feed high-pressure reactor at 235 MPa and a peak temperature of 260° C.

[0088] Polymer C: Terpolymer of ethylene, methyl acrylate (21 wt. %) and vinyltrimethoxysilane (1.0 wt. %), having a MFR.sub.2 of 2 g/10 min. The terpolymer is produced in a tubular front feed high-pressure reactor at 260 MPa and a peak temperature of 255° C.

[0089] CaCO.sub.3: Commercial product by Omya, EXH1SP. Particle size (d.sub.50) 1.4 μm, stearic acid coated (1%).

[0090] Al.sub.2(OH).sub.3: Commercial product by Huber, Martinal OL104LE. Precipitated uncoated aluminium hydroxide with a particle size of (d.sub.50) of 1.6-2.0 μm.

[0091] Mg(OH).sub.2: Commercial product by Huber, Magnifin H5HV. Precipitated and surface treated (polymeric coating) magnesium hydroxide with a particle size of (d.sub.50) 1.7-2.1 μm

[0092] DOTDL: dioctyltin dilaureate, commercially available from Dow Chemical Company Limited under trade name Acima DOTL 99 (CAS No. 3648-18-8), with a purity of minimum 99 wt. %.

[0093] Irganox 1010: Phenolic antioxidant, commercially available from BASF.

[0094] Si-gum: Commerical product by Wacker, Genioplast PA 4455100 VP. Ultra high-molecular weight polydimethyl siloxane polymer with a purity>98 wt. %.

[0095] 3. Results

[0096] The compositions of the Inventive Examples (IE) and comparative examples (CE) are shown in tables 1 and 2 below. The polymers of all inventive examples are terpolymers with butyl acrylate (BA) or methyl acrylate (MA), respectively, as further comonomer as indicated. Comparative examples CE3 to CE6 are also terpolymers.

[0097] A catalyst master batch (MB) containing 2.4 wt. % DOTDL and 2 wt. % Irganox 1010 was produced on a Prism (Prism TSE 24TC) twins screw compounding with an ethylene butyl-acrylate copolymer as polymer carrier. The butyl-acrylate (BA) content was 17 wt. % and the MFR.sub.2 of the ethylene butyl-acrylate copolymer was 4.5 g/10 minutes. The compounding was performed at a temperature setting of 160/160/160/155/155/155° C. and an output of 2 kg/hour. The master batch (MB) was added to the polymer compositions in the amounts as indicated in tables 1 and 2.

[0098] The fillers and additives were added to the respective co- or terpolymers in a Buss 46 mm co-kneater, with a temperature setting of 80/120/110/110/120/120° C.

[0099] The masterbatch (MB) was subsequently dryblended with the polymers/compounds outlined in table 1 and 2. Thereafter a 1.8 mm thick tape was extruded with a temperature profile of 135/145/155° C. with 30 rpm on a Collin TeachLine E20T tape extruder with a 4.2:1, 24D Compression screw, D=20 mm.

[0100] Samples were crosslinked in 90° C. water for 24 h (“Final Hot Set”) or hanging at ambient conditions in a constant room at 55% relative humidity and a temperature of 23° C. (“Ambient”).

[0101] In table 1, the time to reach 60% hot-set elongation is compared for five different silane cross-linkable formulations. Comparative examples 1 and 2 show the crosslinking speed for an unfilled ethylene vinyl trimethoxy silane copolymer at two different concentration of the Lewis acid (DOTDL). When the catalyst level is increased from 0.06 to 0.18 wt. % the time to reach 60% hot-set elongation is decreased from 95 to 55 days for a 1.8 mm thick tape stored at ambient conditions (55% relative humidity 23° C.). In the following examples presented in table 1 butyl acrylate (BA) or methyl acrylate (MA) as a further comonomer is used. Filler CaCO.sub.3 combined with these terpolymers crosslink faster than the unfilled materials. Adding aluminium hydroxide, surprisingly a significant increase in crosslinking speed is noticed, reaching 60% hot-set after 10 days at low catalyst concentration of only 0.02 wt. %. It can also be noticed that for both the Al.sub.2(OH).sub.3 and Mg(OH).sub.2 based compounds the final hot-set level is much lower than for the hydroxide containing compounds. The final crosslinking levels have been measured after curing the 1.8 mm thick tape in a water bath at 90° C. for 24 hours.

TABLE-US-00001 TABLE 1 The influence of CaCO.sub.3, Al.sub.2(OH).sub.3 and Mg(OH).sub.2 on the curing characteristics Example CE 1 CE 2 CE 3 IE 1 IE 2 Polymer type A A B C C MFR.sub.2, g/10 min 1 1 0.5 2 2 VTMS, wt. % 1.35 1.35 1.5 1.0 1.0 Comonomer — — BA/10 MA/21 MA/21 type/wt-% Additives/Fillers in composition Al.sub.2(OH).sub.3, wt-% 0 0 0 60 Mg(OH).sub.2, wt-% 60 CaCO.sub.3, wt-% 0 0 25 0 0 Si-gum, wt. % 0 0 0.4 0 0 Catalyst master 7.5 2.5 5 1 1 batch (MB), wt. % DOTDL, wt. % 0.18 0.06 0.12 0.024 0.024 Irganox 1010, wt. % 0.15 0.05 0.1 0.02 0.02 Hot Set evaluation Ambient, Time to 55 95 35 10 — 60% Hot-set Elongation, days Final Hot-set 35 35 30 6 8 Elongation, %

[0102] In table 2 the effect of lower amounts (5-20 wt. %) of Al.sub.2(OH).sub.3 on the curing speed is shown. Addition of 5 wt. % of Al.sub.2(OH).sub.3 shows no influence on the curing speed, i.e. the Hot Set elongation expressed in %, while at levels of 10 wt. % or more a clear acceleration of the curing speed is surprisingly observed.

TABLE-US-00002 TABLE 2 The effect of lower levels of Al.sub.2(OH).sub.3 on the curing characteristics Example CE 4 CE 5 IE 3 IE 4 IE 5 Polymer type B B B B B MFR.sub.2, g/10 min 0.5 0.5 0.5 0.5 0.5 VTMS, wt. % 1.5 1.5 1.5 1.5 1.5 Comonomer type/wt. % BA/10 BA/10 BA/10 BA/10 BA/10 Additives/Fillers in composition Al.sub.2(OH).sub.3, wt. % 0 5 10 15 20 CaCO.sub.3, wt. % 30 30 30 30 30 Si-gum, wt. % 3.0 3.0 3.0 3.0 3.0 Catalyst master batch 5 5 5 5 5 (MB), wt. % DOTDL, wt. % 0.12 0.12 0.12 0.12 0.12 Irganox 1010, wt. % 0.1 0.1 0.1 0.1 0.1 Hot Set evaluation Hot-set elongation, %;  7 days 139 131 115 99 92 14 days 118 119 82 80 77 30 days 102 106 84 79 69