CROSSLINKING ACCELERATORS FOR POLYMER COMPOSITIONS CONTAINING SILANE GROUPS

Abstract

The present invention relates to a crosslinkable polymer composition, grafted or non-grafted, comprising a crosslinkable copolymer containing hydrolyzable silane groups. The invention further relates to a crosslinked polymer composition obtained by crosslinking the crosslinkable copolymer containing hydrolyzable silane groups and an article comprising such a composition. The present invention also relates to the use of one or more crosslinking accelerators to accelerate the crosslinking of a crosslinkable copolymer containing hydrolyzable silane groups.

Description

CROSSLINKING ACCELERATORS FOR POLYMER COMPOSITIONS CONTAINING SILANE GROUPS Field of Invention The present invention relates to a crosslinkable polymer composition, grafted or non-grafted, comprising a crosslinkable copolymer containing hydrolyzable silane groups. The invention further relates to a crosslinked polymer composition obtained by crosslinking the crosslinkable copolymer containing hydrolyzable silane groups and an article comprising the same. The present invention also relates to the use of one or more crosslinking accelerators to accelerate the crosslinking of a crosslinkable copolymer containing hydrolyzable silane groups. Background of the Invention Crosslinking different polymers using specific additives or compounds is a known practice in the past. Crosslinking improves polymer properties such as mechanical strength and heat resistance. The crosslinking of polymers with hydrolyzable silane groups is known in the prior art and is carried out by a process called moisture curing. In a first step, the silane groups are hydrolyzed under the influence of water, resulting in the cleavage of the alcohol and the formation of / accnn / Lznz / E / YiAi Ref. 317325 the silanol groups. In a second step, the silanol groups are crosslinked by a condensation reaction that splits water. In both steps, a so-called condensation catalyst or a so-called silanol condensation catalyst is used as a catalyst. The curing or crosslinking of polymers with hydrolyzable silane groups at room temperature has been established following the introduction of compatible sulfonic acids as catalysts, as described in EP 0736065 B1. However, such catalysts are deactivated in the presence of additives, such as fillers like CaCO3, metal hydroxides, antimony trioxide, stabilizers, or hindered amine light pigments. Lewis acids, such as dibutyltin dilaureate (DBTDL) or dioctyltin dilaureate (DOTDL), are still commonly used as crosslinking catalysts for moisture-curable compounds containing these additives. A disadvantage of these crosslinking catalysts is the slow crosslinking rate, especially under ambient conditions. Therefore, curing such material combinations typically requires high temperatures of 60–90°C in water bath saunas. However, this approach also increases costs, energy consumption, and the logistical burden of the production process. US 4,549,041 describes silane-grafted polyolefin resins blended with metal hydrate. The metal hydrate, such as aluminum hydroxide or magnesium hydroxide, acts as a flame retardant. US 2003 / 0134969 describes cable compounds comprising a liquid unsaturated organosilane or an unsaturated organosilane supported by a carrier, a thermoplastic base polymer, and a reinforcing, extensible, or flame-retardant mineral filler. The silanes are grafted onto the polymer chains using a free radical generator (ERG). Summary of the Invention It is an object of the present invention to provide a crosslinkable polymer composition comprising a crosslinkable copolymer containing hydrolyzable silane groups, which overcomes the problems mentioned above. It is in particular an object of the present invention to provide a crosslinkable polymer composition comprising a crosslinkable copolymer containing hydrolyzable silane groups which has enhanced crosslinking at room temperature with the use of Lewis acids as the silanol condensation catalyst. It is also an object of the present invention to provide a crosslinkable polymer composition comprising a crosslinkable copolymer containing hydrolyzable silane groups, which has improved crosslinking at all temperatures and at the same time uses reduced amounts of Lewis acids as a silanol condensation catalyst. The present invention is based on the surprising discovery that all the above objects can be achieved with the use of a crosslinking accelerator, in particular a metal hydroxide, an alkali metal hydroxide, an alkaline earth metal hydroxide or mixtures thereof, in combination with a crosslinkable copolymer containing hydrolyzable silane groups. The present invention generally relates to a crosslinkable polymer composition comprising a crosslinkable copolymer containing hydrolyzable silane groups (A). The crosslinkable copolymer containing hydrolyzable silane groups (A) may be (A1) a non-grafted, crosslinkable copolymer containing hydrolyzable silane groups, or (A2) a grafted, crosslinkable copolymer containing hydrolyzable silane groups. In this way, the present invention provides a crosslinkable polymer composition comprising (A) a non-grafted, crosslinkable copolymer containing hydrolyzable silane groups, (B) a condensation catalyst, and (C) a crosslinking accelerator, wherein the condensation catalyst (B) comprises a metal carboxylate. The invention further provides a crosslinkable polymer composition comprising (A2) a crosslinkable grafted copolymer containing hydrolyzable silane groups, (B) a condensation catalyst, and (C) a crosslinking accelerator, wherein the condensation catalyst (B) comprises a metal carboxylate, wherein the crosslinking accelerator (C) comprises a metal hydroxide, an alkali metal hydroxide, an alkaline earth metal hydroxide, or mixtures thereof, and wherein the crosslinking accelerator (C) is present in an amount of 0.01 wt% to 40 wt% based on the total crosslinkable polymer composition. The invention further provides a crosslinked polymer composition obtained by crosslinking the crosslinkable polymer composition according to the invention. The invention also provides an article comprising the crosslinkable polymer composition according to the invention or comprising the crosslinked polymer composition according to the invention. The present invention also provides for the use of one or more crosslinking accelerators (C) selected from the group consisting of a metal hydroxide, an alkali metal hydroxide, an alkaline earth metal hydroxide, or mixtures thereof to accelerate the crosslinking of a crosslinkable copolymer containing hydrolyzable silane groups (A) in the presence of a condensation catalyst (B). The present invention has a number of advantages. The invention describes a solution in which the crosslinking rate of Lewis acids is increased by the use of crosslinking accelerators (C) according to the invention, in particular metal hydroxides, alkali metal hydroxide, and alkaline earth metal hydroxide, thereby making it possible to environmentally cure a crosslinkable copolymer containing hydrolyzable silane groups. By using crosslinking accelerators (C), in particular aluminum hydroxide (ATH) or magnesium hydroxide (MDH), in combination with a crosslinkable copolymer containing hydrolyzable silane groups, high crosslinking rates can be achieved with low concentrations of Lewis acids under all temperature conditions, in this case making it possible to cure the crosslinkable copolymer containing hydrolyzable silane groups also with Lewis acids. The present invention, surprisingly, also achieves not only an improvement in the crosslinking speed, but at the same time, an improvement in the crosslinking levels; in this case, improved levels of thermal hardening can be achieved with a reduced concentration of silane or, alternatively, with an increased concentration of silane-free polymers. Detailed Description of the Invention As mentioned above, the present invention generally relates to a crosslinkable polymer composition comprising a crosslinkable copolymer containing hydrolyzable silane groups (A). A silane compound is introduced as a crosslinkable group either by grafting the silane compound onto the prepared polyolefin or by copolymerizing one or more olefin monomers and monomers containing silane groups. Such techniques are known, for example, from US 4,413,066, US 4,297,310, US 4,351,876, US 4,397,981, US 4,446,283, and US 4,456,704. The crosslinkable, non-grafted copolymer containing hydrolyzable silane groups (Al) is preferably obtained by copolymerizing one or more olefin monomers with an unsaturated silane compound, more preferably by copolymerizing an olefin monomer with an unsaturated silane compound. The copolymerization of one or more olefin monomer(s) with the unsaturated silane compound can be carried out under any suitable conditions that result in the copolymerization of the monomer(s) and the unsaturated silane compound. The unsaturated silane compound is also referred to as monomers containing silane groups. The preferably unsaturated silane compound is represented by formula (I) R1SiR2qY3-q(I) where R1 is an ethylenically unsaturated hydrocarbyl, hydrocarbyloxy, or (meth)acryloxy hydrocarbyl group, R2 is a saturated aliphatic hydrocarbyl group, And, which can be the same or different, is a hydrolyzable organic group and is 0, 1 or 2. Special examples of the unsaturated silane compound are those in which R1 is vinyl, allyl, isopropenyl, butenyl, cyclohexanyl, or gamma-(meth)acryloxy propyl; Y is methoxy, ethoxy, formyloxy, acetoxy, propionyloxy, or an alkyl or arylamino group; and R2, if present, is a methyl, ethyl, propyl, decyl, or phenyl group. A preferred unsaturated silane compound is represented by formula (II) CH2=CHSi (OA)3(II) where A is a hydrocarbyl group having 1-8 carbon atoms, preferably 1-4 carbon atoms. The unsaturated silane compound is preferably one or more selected from the group consisting of vinyl trimethoxysilane (VTMS), vinyl bismethoxyethoxysilane, vinyl triethoxysilane, vinyl triisopropoxysilane, vinyl tri-n-butoxysilane, gamma-(meth)acryloxypropyltrimethoxysilane, gamma(meth)acryloxypropyltriethoxysilane, and vinyl triacetoxysilane. More preferably, the unsaturated silane compound is a vinyltrimethoxysilane (VTMS). The olefin monomer is one or more selected from the group consisting of ethylene, propylene, or butylene, more preferably the olefin monomer is ethylene. In preferred embodiments of the invention, the non-grafted, crosslinkable copolymer containing hydrolyzable silane groups (Al) is obtained by copolymerizing ethylene with vinyltrimethoxysilane (VTMS). The crosslinkable, non-grafted copolymer (Al) preferably contains from 0.001 wt% to 15 wt% of hydrolyzable silane groups, more preferably from 0.01 wt% to 5 wt%, most preferably from 0.1 wt% to 2 wt%. A copolymer is a material formed by polymerizing at least two different monomers. For example, a terpolymer, which is formed by polymerizing three different monomers, also falls under the definition of a copolymer. Copolymerization can also be implemented by copolymerizing an olefin monomer as described above with an unsaturated silane compound as described above in the presence of one or more different comonomers, preferably in the presence of another comonomer. Preferably, the copolymerization is carried out in the presence of one or more other comonomers, more preferably the copolymerization is carried out in the presence of another comonomer. The other comonomer(s) is preferably a comonomer containing an acrylate group, more preferably the other comonomer is one or more selected from the group consisting of methyl acrylate, ethyl acrylate, butyl acrylate, or a mixture thereof, and most preferably the other comonomer is either methyl acrylate or butyl acrylate. The total comonomer content of the crosslinkable, non-grafted copolymer (Al) is preferably 0.5% by weight to 70% by weight of the copolymer, more preferably approximately 1% by weight to 35% by weight, and most preferably 5% by weight to 30% by weight. The crosslinkable, non-grafted copolymer containing hydrolyzable silane groups (Al) is present in an amount preferably of 94 wt% to 22 wt%, more preferably 85 wt% to 25 wt%, more preferably 75 wt% to 30 wt%, and most preferably 65 wt% to 35 wt% based on the total crosslinkable polymer composition. The crosslinkable polymer composition of the invention comprises a condensation catalyst (B), which comprises a metal carboxylate. Preferably, the metal of the metal carboxylate is selected from the group consisting of tin, zinc, iron, lead, or cobalt. More preferably, the metal of the metal carboxylate is tin. Preferably, the condensation catalyst (B) is one or more selected from the group of dibutyltin dilaureate (DBTDL), dioctyltin dilaureate (DOTDL), dibutyltin diacetate, stannous acetate, stannous caprylate, zinc caprylate, lead naphthenate, and cobalt naphthenate. More preferably, the condensation catalyst (B) is dibutyltin dilaureate, dioctyltin dilaureate, or a mixture thereof; most preferably, the condensation catalyst (B) is dioctyltin dilaureate (DOTDL). The condensation catalyst (B) is present in an amount preferably from 0.001 wt% to 3 wt%, more preferably from 0.005 wt% to 2 wt%, more preferably from 0.0075 wt% to 1 wt%, more preferably from 0.01 wt% to 0.5 wt%, and most preferably from 0.02 wt% to 0.15 wt% based on the total crosslinkable polymer composition. The condensation catalyst (B) is preferably added as a master blend (MB) to the crosslinkable polymer composition. The master blend preferably comprises the condensation catalyst (B) and a polymer carrier, and optionally an antioxidant, as described below. The polymer carrier is preferably an ethylene copolymer, more preferably an ethylene copolymer and a monomer containing alkyl acrylate groups, and most preferably an ethylene-butyl acrylate copolymer. The crosslinkable polymer composition of the invention comprises a crosslinking accelerator (C). The crosslinking accelerator (C) preferably comprises a metal hydroxide, an alkali metal hydroxide, an alkaline earth metal hydroxide, or mixtures thereof. More preferably, the crosslinking accelerator (C) comprises a metal hydroxide and / or an alkaline earth metal hydroxide. The metal in the metal hydroxide is preferably Al. The alkaline earth metal in the alkaline earth metal hydroxide is preferably Mg. Preferably, the crosslinking accelerator (C) comprises A12(OH)3, Mg(OH)2 or mixtures thereof, more preferably the crosslinking accelerator (C) consists of A12(OH)3 and / or Mg(OH)2. The crosslinking accelerator (C) is present in an amount preferably of 6% by weight to 75% by weight, more preferably of 8% by weight to 70% by weight, more preferably of 9% by weight to 65% by weight and most preferably of 10% by weight to 60% by weight based on the total crosslinkable polymer composition. The crosslinkable polymer composition according to the invention has an MFR2 preferably of 0.1 to 15 g / 10 min, more preferably of 0.2 to 10 g / 10 min, more preferably of 0.3 to 5 g / 10 min, and most preferably of 0.4 to 2.5 g / 10 min determined according to ISO 1133. The crosslinkable polymer composition preferably further comprises a filler. The filler preferably comprises, more preferably consists of, calcium carbonate. The filler is present in an amount preferably of 0.01 wt% to 40 wt%, more preferably of 0.1 wt% to 38 wt%, more preferably of 1 wt% to 36 wt%, more preferably of 5 wt% to 34 wt%, more preferably of 15 wt% to 32 wt%, and most preferably of 20 wt% to 30 wt% based on the total crosslinkable polymer composition. The crosslinkable polymer composition preferably further comprises an additive. The additive comprises, more preferably consists of, a siloxane polymer. The siloxane polymer is preferably a polymethylsiloxane polymer. The additive is present in an amount preferably from 0.01% by weight to 6% by weight, more preferably from 0.05% by weight to 5% by weight, more preferably from 0.1% by weight to 4.5% by weight, more preferably from 0.2% by weight to 4% by weight and most preferably from 0.3% by weight to 3.5% by weight based on the total crosslinkable polymer composition. The crosslinkable polymer composition preferably further comprises an antioxidant. The antioxidant preferably comprises, more preferably consists of, a phosphorus-containing antioxidant and / or a phenolic antioxidant. The phenolic antioxidant preferably is pentaerythrityl-tetrakis(3-(3', 5'-di-tert-butyl-4-hydroxyphenyl)propionate, commercially available from BASF as Irganox 1010. / accnn / Lznz / E / YiAi The antioxidant is present in an amount preferably of 0.001% to 2% by weight, more preferably of 0.005% to 1% by weight, more preferably of 0.007% to 0.5% by weight, more preferably of 0.01% to 0.25% by weight, and most preferably of 0.02% to 0.1% by weight based on the total crosslinkable polymer composition. The present invention further provides a crosslinkable polymer composition comprising a crosslinkable graft copolymer containing hydrolyzable silane groups (A2). As discussed above, the hydrolyzable silane group can be introduced into the polymer by grafting, in this case, by chemically modifying the polymer through the addition of the silane group, primarily in a radial reaction. This technique is well known in the prior art. If a graft copolymer is used, it may have been produced, for example, by either of the two methods described in US 3,646,155 and US 4,117,195, respectively. All preferred embodiments for the crosslinkable polymer composition comprising a non-grafted crosslinkable copolymer containing hydrolyzable silane groups (Al), described above, are preferred embodiments of the crosslinkable polymer composition comprising a grafted crosslinkable copolymer containing hydrolyzable silane groups (A2), if applicable. Accordingly, all preferred embodiments of the condensation catalyst (B) as described above for the crosslinkable polymer composition comprising a non-grafted crosslinkable copolymer containing hydrolyzable silane groups (Al) are preferred embodiments for the condensation catalyst (B) of the crosslinkable polymer composition comprising a grafted, crosslinkable copolymer containing hydrolyzable silane groups (A2), if applicable. Furthermore, all preferred embodiments of the crosslinking accelerator (C) as described above for the crosslinkable polymer composition comprising a crosslinkable, non-grafted copolymer containing hydrolyzable silane groups (Al) are preferred embodiments for the crosslinking accelerator (C) of the crosslinkable polymer composition comprising a grafted, crosslinkable copolymer containing hydrolyzable silane groups (A2), if applicable. The crosslinking accelerator (C) is present in an amount preferably from 0.1% by weight to 50% by weight, more preferably from 1% by weight to 30% by weight, and most preferably from 6% by weight to 20% by weight based on the total crosslinkable polymer composition. The present invention further provides a crosslinked polymer composition obtained by crosslinking the crosslinkable polymer composition according to the invention. In this case, the invention provides a crosslinked polymer composition obtained by crosslinking the crosslinkable polymer composition comprising a non-grafted crosslinkable copolymer containing hydrolyzable silane groups (Al) according to the invention or the crosslinkable polymer composition comprising a grafted crosslinkable copolymer containing hydrolyzable silane groups (A2) according to the invention. The crosslinking of the crosslinkable polymer composition of the invention is preferably carried out by moisture curing as known in the prior art. Reference is made to, for example, WO 95 / 17463 and WO 00 / 36612. In a first step, the silane groups are hydrolyzed under the influence of water or steam, resulting in the cleavage of the alcohol and the formation of the silanol groups. In a second step, the silanol groups are crosslinked by a condensation reaction that cleaves water. In both steps, a so-called silanol condensation catalyst is used as a catalyst. Crosslinking can be carried out under ambient conditions, preferably at a relative humidity of 45% to 65% and a temperature of 20°C to 25°C, most preferably at a relative humidity of 55% and a temperature of 23°C. Crosslinking can also be carried out at an elevated temperature, preferably 70°C to 90°C in water. The invention further provides an article comprising the crosslinkable polymer composition according to the invention or comprising the crosslinked polymer composition according to the invention. Preferably, the article is a cable insulator, cable sheath, or pipe. Preferably, the cable comprises an insulating layer, and the insulating layer comprises the crosslinkable polymer composition according to the invention or comprises the crosslinked polymer composition according to the invention. Ideally, the cable should be a low-voltage power cable. However, the technology is applicable to all types of cables. The present invention also provides for the use of one or more crosslinking accelerators (C) selected from the group consisting of a metal hydroxide, an alkali metal hydroxide, an alkaline earth metal hydroxide, or mixtures thereof to accelerate the crosslinking of a crosslinkable copolymer containing hydrolyzable silane groups (A) in the presence of a condensation catalyst (B). All preferred embodiments of the crosslinkable polymer composition comprising a non-grafted crosslinkable copolymer containing hydrolyzable silane groups (Al) described above and of the crosslinkable polymer composition comprising a grafted, crosslinkable copolymer containing hydrolyzable silane groups (A2) are preferred embodiments of use according to the invention, if applicable. Accordingly, all preferred embodiments of the condensation catalyst (B) as described above for the crosslinkable polymer composition comprising a crosslinkable, non-grafted copolymer containing hydrolyzable silane groups (Al) and the crosslinkable polymer composition comprising a crosslinkable, grafted copolymer containing hydrolyzable silane groups (A2) are preferred embodiments for the condensation catalyst (B) for use of the invention, if applicable. Furthermore, all preferred embodiments of the crosslinking accelerator (C) as described above for the crosslinkable polymer composition comprising a crosslinkable, non-grafted copolymer containing hydrolyzable silane groups (Al) and the crosslinkable polymer composition comprising a grafted, crosslinkable copolymer containing hydrolyzable silane groups (A2) are preferred embodiments for the crosslinking accelerator (C) use of the invention, if applicable. Preferably, the crosslinkable copolymer (A) is a non-grafted copolymer as described above. EXAMPLES 1. Measurement methods a) flow index The melt flow index (MFR2) is determined according to ISO 1133 and is indicated in g / 10 minutes. For ethylene-based polymers, the determination is made with a load of 2.16 kg and at a temperature of 190°C. For propylene-based polymers, the determination is made with a load of 2.16 kg and at a temperature of 230°C. b) Hot Elongation The crosslinking rate of the polymer composition was determined as the Hot Elongation according to IEC 811-2-1-9. The Hot Elongation test was performed on tensile test specimens prepared from the tape at 200°C with 20 N / cm², and the elongation of the sample was measured after 15 min, following IEC 811-2-1-9. The tape is prepared as described below. 2. Materials Polymer A: Ethylene-vinyl trimethoxysilane copolymer (1.35 wt%), which has an MFR2 of 1.0 g / 10 min. The copolymer is produced in a front-feed high-pressure tubular reactor at 235 MPa and a maximum temperature of 260°C. Polymer B: Ethylene terpolymer, butyl acrylate (10 wt%) and vinyltrimethoxysilane (1.5 wt%), the terpolymer having an MFR2 of 0.5 g / 10 min. The terpolymer is produced in a front-feed high-pressure tubular reactor at 235 MPa and a maximum temperature of 260°C. Polymer C: Terpolymer of ethylene, methyl acrylate (21 wt%) and vinyltrimethoxysilane (1.0 wt%), which has an MFR2 of 2 g / 10 min. The terpolymer is produced in a front-feed high-pressure tubular reactor at 260 MPa and a maximum temperature of 255°C. CaCOa: Commercial product of Omya, EXH1SP. Particle size (d50) 1.4 pm, coated with stearic acid (1%). A12(OH)3: Huber Martinal OL104LE commercial product. Uncoated precipitated aluminum hydroxide with a particle size of (d50) of 1.6-2.0 pm. Mg(OH)2: Huber commercial product, Magnifin H5HV. / accnn / Lznz / E / YiAi Precipitated and surface-treated magnesium hydroxide (polymer coating) with a particle size of (d50) 1.7-2.1 pm. DOTDL: Dioctyltin dilaureate, commercially available from Dow Chemical Company Limited under the trade name Acima DOTL 99 (CAS No. 3648-18-8), with a minimum purity of 99% by weight. Irganox 1010: Phenolic antioxidant, commercially available from BASF. Si-goma: Wacker commercial product, Genioplast PA 4455100 VP. Ultra high molecular weight polydimethylsiloxane polymer with a purity > 98% by weight. 3. Results The compositions of the Inventive Examples (IE) and Comparative Examples (CE) are shown in Tables 1 and 2 below. The polymers in all the inventive examples are terpolymers with butyl acrylate (BA) or methyl acrylate (MA), respectively, as an additional comonomer as indicated. Comparative Examples CE3 to CE6 are also terpolymers. A catalyst master mix (MB) containing 2.4 wt% DOTDL and 2 wt% Irganox 1010 was produced in a Prism twin-screw mixer (Prism TSE 24TC) using an ethylene butyl acrylate copolymer as a polymer carrier. The butyl acrylate (BA) content was 17 wt%, and the MFR2 of the ethylene butyl acrylate copolymer was 4.5 g / 10 mins. Mixing was carried out at a temperature of 160 / 160 / 160 / 155 / 155 / 155°C and a throughput of 2 kg / hr. The master mix (MB) was added to the polymer compositions in the amounts indicated in Tables 1 and 2. The fillers and additives were added to the respective copolymers or terpolymers in a 46 mm Buss co-kneader, with a temperature setting of 80 / 120 / 110 / 110 / 120 / 120°C. Subsequently, the master mix (MB) was dry-mixed with the polymers / compounds described in Tables 1 and 2. After that point, a 1.8 mm thick ribbon was extruded with a temperature profile of 135 / 145 / 1550C at 30 rpm in a Collin TeachLine E20T ribbon extruder with a 4.2:1, 24D, D = 20 mm compression screw. The samples were crosslinked in water at 90°C for 24h (Final Hot Elongation) or hung under ambient conditions in a room of constant conditions at 55% relative humidity and a temperature of 2-3°C (Ambient). Table 1 compares the time to reach 60% hot elongation for five different silane crosslinkable formulations. Comparative examples 1 and 2 show the crosslinking rate for an unfilled ethylene vinyl trimethoxysilane copolymer at two different Lewis acid (DOTDL) concentrations. When the catalyst level is increased from 0.06 to 0.18 wt.%, the time to reach 60% hot elongation decreases from 95 to 55 days for a 1.8 mm thick tape stored under ambient conditions (55% relative humidity at 23°C). In the subsequent examples presented in Table 1, butyl acrylate (BA) or methyl acrylate (MA) is used as an additional comonomer. The CaCO₃ filler combined with these terpolymers crosslinks faster than the unfilled materials.Upon the addition of aluminum hydroxide, a surprisingly significant increase in the crosslinking rate is observed, reaching 60% hot elongation after 10 days at a low catalyst concentration of only 0.02 wt%. It can also be seen that for both compounds based on Al₂(OH)₃ and Mg(OH)₂, the final hot elongation level is much lower than for the hydroxide-containing compounds. The final crosslinking levels were measured after curing the 1.8 mm thick tape in a 90°C water bath for 24 hours. / accnn / Lznz / E / YiAi Table 1: The influence of CaCOs, Α1ς(ΟΗ)3 and Mg(OH)2 on the curing characteristics Example CE 1 CE 2 CE 3 IE 1 IE 2 Polymer type AABCC MFR2, g / lOmin 1 1 0.5 2 2 VTMS, wt. % 1.35 1.35 1.5 1.0 1.0 Comonomer type / wt. % — — BA / 10 MA / 21 MA / 21 Additives / Fillers in composition Al2(OH)3, wt. % 0 0 0 60 Mg(OH)2, wt. % 60 CaCO3, wt. % 0 0 25 0 0 Si-gum, wt. % 0 0 0.4 0 0 Catalyst Master Mix (MB), wt. % 7.5 2.5 5 1 1 DOTDL, wt. % 0.18 0.06 0.12 0.024 0.024 Irganox 1010, % by weight 0.15 0.05 0.1 0.02 0.02 Ambient Hot Elongation Evaluation, time for 60% Elongation of Hot Elongation, days 55 95 35 10 Final Hot Elongation, % 35 35 30 6 8 Table 2 shows the effect of smaller amounts (5-20 wt%) of Al2(OH)3 on the curing rate. The addition of 5 wt% Al2(OH)3 shows no influence on the curing rate; in this case, the Hot Elongation is expressed as a percentage. However, at levels of 10 wt% or more, a surprisingly clear acceleration of the curing rate is observed. Table 2: The effect of lower levels of A1ς(OH)3 on curing characteristics Example CE 4 CE 5 IE 3 IE 4 IE 5 Polymer Type BBBBB MFR2, g / lOmin 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 A12(OH)3, wt. % 0 5 10 15 20 CaCOs, wt. % 30 30 30 30 30 Si-gum, wt. % 3.0 3.0 3.0 3.0 3.0 Catalyst Master Mix (MB), wt. % 5 5 5 5 5 DOTDL, wt. % 0.12 0.12 0.12 0.12 0.12 Irganox 1010, % by weight 0.1 0.1 0.1 0.1 0.1 Hot Elongation Evaluation Hot Elongation, %; 7 days 139 131 115 99 92 14 days 118 119 82 80 77 30 days 102 106 84 79 69 / accnn / Lznz / E / YiAi It is hereby stated that, as of this date, the best method known to the applicant for putting the aforementioned invention into practice is the one that is clear from the present description of the invention.

Claims

Having described the invention as above, the following claims are claimed as property:

1. A crosslinkable polymer composition characterized in that it comprises (A) a non-grafted, crosslinkable copolymer containing hydrolyzable silane groups, (B) a condensation catalyst, and (C) a crosslinking accelerator, wherein the non-grafted, crosslinkable copolymer containing hydrolyzable silane groups (A) is obtained by copolymerizing one or more monomers of a given material with an unsaturated silane compound, wherein the condensation catalyst (B) comprises a metal carboxylate, and wherein the crosslinking accelerator (C) is present in an amount of 6 to 75% by weight based on the total crosslinkable polymer composition.

2. The crosslinkable polymer composition according to claim 1, characterized in that the metal of the metal carboxylate is selected from the group consisting of tin, zinc, iron, lead or cobalt.

3. The crosslinkable polymer composition according to any of the preceding claims, / accnn / Lznz / E / YiAi characterized in that the condensation catalyst (B) is present in an amount of 0.001% by weight to 3% by weight based on the total crosslinkable polymer composition.

4. The crosslinkable polymer composition according to any of the preceding claims, characterized in that the crosslinking accelerator (C) comprises a metal hydroxide, an alkali metal hydroxide, an alkaline earth metal hydroxide, or mixtures thereof.

5. The crosslinkable polymer composition according to any of the preceding claims, characterized in that the crosslinking accelerator (C) comprises A12(OH)3, Mg(OH)2 or mixtures thereof.

6. The crosslinkable polymer composition according to claims 1 to 5, characterized in that 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-butoxysilane, gamma(meth)acryloxypropyltrimethoxysilane, gamma(meth)acryloxypropyltriethoxysilane, and vinyl triacetoxysilane.

7. The crosslinkable polymer composition according to claims 1 to 6, characterized in that the monomer defined is one or more selected from the group consisting of ethylene, propylene, or butylene.

8. The crosslinkable polymer composition according to claims 1 to 7, characterized in that the copolymerization 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.

9. The crosslinkable polymer composition according to claims 1 to 8, characterized in that it comprises a filler, wherein the filler is present in an amount of 0.01% by weight to 40% by weight based on the total crosslinkable polymer composition.

10. A crosslinkable polymer composition characterized in that it comprises (A2) a crosslinkable graft copolymer containing hydrolyzable silane groups, (B) a condensation catalyst, and (C) a crosslinking accelerator, wherein the condensation catalyst (B) comprises a metal carboxylate, and wherein the crosslinking accelerator (C) comprises a metal hydroxide, an alkali metal hydroxide, an alkaline earth metal hydroxide, or mixtures thereof, and wherein the crosslinking accelerator (C) is present in an amount of 6 wt% to 75 wt% based on the total crosslinkable polymer composition.

11. A crosslinked polymer composition characterized in that it is obtained by crosslinking the crosslinkable polymer composition according to any of the preceding claims. 5 12. An article characterized in that it comprises the crosslinkable polymer composition according to claim 1-10 or comprising the crosslinked polymer composition according to claim 11.

13. The use of one or more crosslinking accelerators (C) 10 selected from the group consisting of a metal hydroxide, an alkali metal hydroxide, an alkaline earth metal hydroxide or mixtures thereof to accelerate the crosslinking of a crosslinkable, non-grafted copolymer containing the hydrolyzable silane groups (A) in the presence 15 of a condensation catalyst (B), wherein the crosslinkable, non-grafted copolymer containing hydrolyzable silane groups (A) is obtained by copolymerizing one or more olefinic monomers with an unsaturated silane compound.