Halogen-free, flame-retardant composition

Abstract

The present invention relates to a halogen-free, flame-retardant composition, comprising (i) at least one halogen-free, thermoplastic base resin, (ii) at least one metal hydroxide, (iii) at least one silane of the following general formula R1n Si (O-R2)4-n or the partial hydrolysate thereof, wherein R1 is independently selected from an unsaturated hydrocarbon compound with at least 2 C atoms and which is optionally substituted and / or comprises at least one heteroatom, R2 is independently selected from an alkyl or alkenyl group with at least 4 C atoms and which is optionally substituted and / or comprises at least one heteroatom, where n is 1, 2 or 3, and (iv) optionally at least one auxiliary material and a cable, comprising the composition according to the invention.

Description

[0001] WA12410S / WI Halogen-free, flame-retardant composition The present invention relates to a halogen-free, flame-retardant composition comprising, among other things, a silane of the following general formula R 1 n Si (OR 2)4-or its partial hydrolysate with the definition described below, as well as a cable comprising this composition. The market for plastic compounds for cable applications is growing steadily, driven by the increasing demand in the E&E sector (e-mobility). Various thermoplastics, additives, stabilizers, peroxides, and crosslinkers are used as base materials for cable production. Among the thermoplastics used for cable sheathing are polyethylene, ethylene vinyl acetate (EVA), and ethylene propylene diene monomer rubber (EPDM). These plastics are used either alone or in blends. These plastics are halogen-free and possess excellent electrical insulation properties, but would be highly flammable without further treatment.To enable their use in the production of HFFR (halogen-free, highly filled, flame-retardant cable compounds), mineral fillers such as aluminum trihydroxide or magnesium dihydroxide are added in relatively high concentrations as flame retardants. These significantly reduce the flammability and smoke formation of the cables in the event of a fire. Various silanes are also used as crosslinking agents in these compounds. During the peroxide crosslinking of the HFFR compounds, these silanes improve the compatibility of the fillers with the polymer matrix. They are also responsible for a partially improved covalent bond between the fillers used as flame retardant additives and the WA12410S / WI 2 matrix. Simultaneously, they create crosslinking sites and thereby improve the mechanical resistance of the underlying compounds – even at higher temperatures.Crosslinking results in lower water absorption and / or increased cable flexibility. Simultaneously, it reduces permanent deformation after exposure to mechanical loads. The crosslinking process is also essential for improved surface quality of the cable sheathing. The flammability of the treated compounds is reduced. It is state of the art to use vinyltrimethoxysilane as a crosslinker; see, for example, WO 2006 / 132452 A1. This crosslinker exhibits a good combination of crosslinking and bonding of the fillers to the matrix, as well as improvement of the mechanical properties of the underlying cable compounds. However, it has been shown that the byproduct 2-methoxyethanol, which is inevitably formed when using vinyltrimethoxysilane, has been classified as a reproductive toxicant in Europe and is therefore classified as a so-called CMR substance.This makes the use of this silane critical from an occupational safety perspective, and therefore alternatives to this silane were sought. As an alternative, oligomerized vinylsilane mixtures were subsequently developed. These oligomerized vinylsilanes exhibit good mechanical properties and, among other things, release relatively harmless methanol or ethanol. However, they have the disadvantage of still having increased volatility due to residual monomers and exhibiting relatively low flash points of 30 °C to 70 °C. These low flash points significantly complicate their technical use in the WA12410S / WI 3 compounding industry due to safety concerns. The oligomerized vinylsilane mixtures cannot therefore adequately replace the currently used vinyltrimthoxyethoxysilane with its advantageous high flash point of > 92 °C for technical applications. The task, therefore, was to develop a vinylsilane or...The goal was to provide oligomerized, reactive vinylsilane as a crosslinking agent in plastic compounds, which on the one hand has a high flash point but on the other hand does not produce any harmful release products. Surprisingly, it has now been found that this task can also be accomplished by long-chain vinylalkoxysilanes, which have long-chain alcohols as release products. It is known from the literature (e.g., https: / / technical.gelest.com / brochures / silane-coupling-agent / silane-coupling-agents / ) that the hydrolysis rate of vinylalkoxysilanes decreases drastically with increasing chain length of the alkoxy group. For example, the relative hydrolysis rate (compared to vinyltrimethoxysilane) of vinyltriethoxysilane is only 0.05, and of vinyltriisopropoxysilane only 0.0015.In contrast, prior art vinyltrimethoxysilane exhibits a high relative hydrolysis rate of 0.5, due to its higher polarity compared to longer-chain aliphatic alcohols. It was therefore expected that the use of longer-chain alcohols as substituents in vinylalkoxysilanes according to the invention would result in these products exhibiting significantly slower kinetics during hydrolysis and condensation processes compared to vinylsilanes such as vinyltrimethoxysilane, vinyltriethoxysilane, or vinyltrimethoxysilane. Since these hydrolysis and condensation processes play an essential role in the incorporation of fillers into the polymer matrix and in crosslinking processes, it was anticipated that the use of the longer-chain vinyltrialkoxysilanes according to the invention would lead to inferior mechanical properties in the polymer compounds produced with them.It was therefore all the more surprising that the supposedly slow-reacting vinylsilanes according to the invention, based on longer-chain aliphatic alcohols, are not only advantageous with regard to the toxicological properties of the release products when incorporated into plastic compounds, but also lead to improved mechanical properties compared to the prior art. Furthermore, the high flash points of the vinylalkoxysilanes according to the invention (e.g., 108 °C for vinyltributoxysilane) also meet the necessary safety-related requirements. A first object of the invention is thus directed to a halogen-free, flame-retardant composition comprising: (i) at least one halogen-free, thermoplastic base resin, (ii) at least one metal hydroxide, WA12410S / WI 5, (iii) at least one silane of the following general formula (I) or its partial hydrolysate, R. 1 n Si (OR 2 )4-n (Formula I) wherein R 1independently selected from an unsaturated hydrocarbon compound comprising at least 2 C atoms, preferably 2-8 C atoms, in particular 2-6 C atoms, R, optionally substituted and / or comprising at least one heteroatom. 2(iv) is selected independently of one another from an alkyl or alkenyl group, optionally substituted and / or comprising at least one heteroatom, with at least 4 carbon atoms, preferably 4-8 carbon atoms, in particular 4-6 carbon atoms, and n1, 2 or 3, preferably 1, and (iv) optionally at least one auxiliary substance. Examples of heteroatoms are O, N, P or S, preferably O. The at least one halogen-free thermoplastic base resin is preferably selected from the group consisting of polyethylene, such as LLDPE, LDPE or HDPE, ethylene vinyl acetate (EVA) and ethylene propylene diene rubber (EPDM). WA12410S / WI 6 In a particular embodiment, the proportion of at least one halogen-free thermoplastic base resin (i) in the total amount of the halogen-free flame-retardant composition is 15 - 50 wt.%, preferably 20 - 40 wt.%, more preferably 25% - 35%.The at least one metal hydroxide is in particular a flame-retardant metal hydroxide, especially preferably selected from the group consisting of aluminum hydroxide, magnesium hydroxide and calcium hydroxide. In a particular embodiment, the proportion of the at least one metal hydroxide (ii) in the total amount of the halogen-free, flame-retardant composition is 40–75 wt.%, preferably 50–70 wt.%, more preferably 55–65 wt.%. 1 represents in particular a vinyl group, possibly substituted and / or comprising at least one heteroatom, especially preferably -CH=CH2. R 2 R2 represents, in particular, an alkyl group that may be substituted and / or comprises at least one heteroatom. In a particular embodiment, R2 is a butyl, pentyl, or hexyl group, especially a butyl group. It is preferred that in formula (I) all R 2are identical. The silane of formula (I) is particularly preferably a vinyltributoxysilane. The silane according to formula (I) can be monomeric or oligomeric; silanes in their monomeric form are more preferred. WA12410S / WI 7 It is preferred that the proportion of the at least one silane (iii) in the total amount of the halogen-free, flame-retardant composition is 0.1–2 wt.%, preferably 0.2–1.5 wt.%, more preferably 0.3–0.7 wt.%. The auxiliary substance can be a stabilizer or initiator; a peroxide initiator, such as Perkadox 14 / 40, is more preferred. It is preferred that the proportion of the at least one auxiliary substance (iv) in the total amount of the halogen-free, flame-retardant composition is 0.2–1.5 wt.%.The objective was to leverage the already extensively described properties of vinyltrimethoxysilane with the newly developed vinyltributoxysilane to optimize and improve surface properties, mechanical properties, and processing in cable applications. A key advantage here is the relatively high flash point of vinyltributoxysilane (108 °C) compared to the previously used vinyltrimethoxysilane (92 °C) or other oligomerized vinylsilanes such as Dynasylan 6490 (87 °C) or Dynasylan 6498 (75 °C). The silanes are incorporated according to state-of-the-art techniques, preferably on a standard rolling mill. All ingredients are homogeneously mixed and then crosslinked in a press at 10 N / mm². Test specimens were punched from the crosslinked sheets and subsequently tested according to standards; see examples below.WA12410S / WI 8 Another object of the present invention is directed to a cable, in particular an HFFR cable, comprising the halogen-free, flame-retardant composition described above.

[0002] WA12410S / WI 9 Exemplary embodiments 1. Raw materials used In the exemplary embodiments of the present invention, the following raw materials are used, among others. Vistalon 7001: Ethylene Propylene Diene Terpolymer Rubber, ExxonMobil Escorene UL 02020: Ethylene Vinyl Acetate Copolymer, VA content 20%, ExxonMobil Martinal OL 111: Aluminum Trihydroxide, Huber Advanced Materials Irganox 1010: Di-tert-butyl hydroxyphenylpropionate, Stabilizer, BASF Artomer 350: Trimethylolpropane trimethacrylate, ANCOMER Perkadox 14 / 40: Bis(tert-butyl-peroxyisopropyl)benzene, AKZOGENIOSIL® GF 51: Oligomeric boiling product of vinyl triethoxysilane, Wacker Chemie AG GENIOSIL® GF 58: Vinyltrimethoxysilane, Wacker Chemie AG Vinyltributoxysilane WA12410S / WI 10 2. Preparation of the formulations 4 approaches (2000 g) were mixed on a roller mill at 80 °C and all ingredients were dispersed. Table 1 shows the compositions of examples 1-4.The quantities are given in parts per hundred rubber (phr) with wt.% in parentheses. Table 1: Composition of test mixtures B. eispiel-Nr. 1 2 3 4 Vistalon 7001 50 (16.6) 50 (16.5) 50 (16.5) 50 (16.5)Escorene UL 02020 50 (16.6) 50 (16.5) 50 (16.5) 50 (16.5)Martinal OL 111 180 (59.7) 180 (59.4) 180 (59.4) 180 (59.4)Paraffin oil 10 (3.3) 10 (3.3) 10 (3.3) 10 (3.3)ZnO 5 (1.7) 5 (1.6) 5 (1.6) 5 (1.6)Irganox 1010 0.15(0.05) 0.15 (0.05) 0.15 (0.05) 0.15 (0.05)Sartomer 350 4.5 (1.5) 4.5 (1.5) 4.5 (1.5) 4.5 (1.5)Perkadox 14 / 40 2 (0.7) 2 (0.7) 2 (0.7) 2 (0.7)Vinyltrimethoxy- 1,5 (0,5)ethoxysilane Vinyltributoxysilane 1.5 (0.5) GENIOSIL® GF 51 1.5 (0.5) Example 1 represents a mixture without silane as a crosslinking additive. Example 2 contains the crosslinker vinyltri(2-methoxyethoxy)silane, which is known in the art. The vinyltrimethoxysilane releases 2-methoxyethanol during the reaction. This residue is classified as a CMR substance and is reprotoxic. The flash point of this silane is 92 °C. Example 3 is an example according to the invention comprising a long-chain vinyltrialkoxysilane. A high flash point of >90 °C is crucial for its application. In the alternative vinyltributoxysilane, the release product is 1-butanol WA12410S / WI 11 (non-toxic). The flash point was determined to be 108 °C (DIN EN ISO 2719). Example 4 comprises the crosslinking agent GENIOSIL® GF 51 (cooking product of vinyltriethoxysilane), which is known in the art as an alternative to vinyltrimethoxysilane. The byproduct is ethanol.A disadvantage of this alternative is the relatively low flash point of 34 °C (DIN EN ISO 2719). 3. Further Processing 2.1. Pressed Plates Two pressed plates, each 2 mm thick, were produced from the premixed roller skins from Table 1 at 185 °C / 10 N / mm² for 20 minutes. 4. Examination and Evaluation of the Specimens The pressed plates from 2.1 were stored for 2 days in standard climate conditions at 23 °C and 50% relative humidity. 4.1. Tensile Test Specimens were produced from the pressed plates and tested for tensile strength [MPa] and elongation at break [%] according to DIN 51220. 4. .2. CoFCoF is determined according to ISO 8295 Plastics – Films and sheets – Determination of coefficients of friction. WA12410S / WI 12 The COF is given without units and was measured using press plates. 4.3. Water absorption Specimens with dimensions of 3 x 3 cm were punched from the press plates and the water absorption was then measured according to DIN EN ISO 62. 4.4. Compression set Specimens with a thickness of 6 mm were punched from the press plates and the C-set was determined according to ASTM 395. Lower compression sets are preferred here. 4 .5. LOI Test specimens with a thickness of 6 mm were punched from the pressed boards and their fire behavior was determined according to DIN EN ISO 4589. Higher LOI (Limited Oxygen Index) values ​​are advantageous in the final application. 4.6. Shore D Hardness Test specimens with a thickness of 6 mm were punched from the pressed boards and their hardness was determined according to DIN 868. WA12410S / WI 13 5. Results Table 2: Results 1 2 3 4Tensile strength 8 11.8 11.8 11.1 [MPa] Elongation at break [%] 168 142.4 160 71.3 Shore D hardness 44.4 46.8 46.4 44.9 CoF 0.35 0.19 0.23 0.605 Water absorption [%] 1.6 0.7 0.7 0.6 LOI [%] 38 40 42 29 C-Set [%] 23°C / 22h 43.8 38.2 33.3 48.1 As can be seen in Table 2, vinyltributoxysilane surprisingly shows comparable or even slightly better properties compared to standard vinyltrimethoxysilane. Vinyltributoxysilane performs particularly well in terms of C-Set (permanent deformation) and LOI value. Improved flame resistance was observed in the fire behavior (LOI).

Claims

WA12410S / WI 14 Claims 1. Halogen-free, flame-retardant composition comprising: (i) at least one halogen-free thermoplastic base resin, (ii) at least one metal hydroxide, (iii) at least one silane of the following general formula (I) or a partial hydrolysate thereof, R 1 n Si (OR 2 ) 4-n (Formula I) wherein R 1 independently selected from an unsaturated hydrocarbon compound with at least 2 carbon atoms, optionally substituted and / or comprising at least one heteroatom, R 2 (iv) is selected independently of each other from an alkyl or alkenyl group comprising at least 4 carbon atoms, optionally substituted and / or comprising at least one heteroatom, and represents n1, 2 or 3, and (iv) optionally at least one auxiliary substance. WA12410S / WI 152. Halogen-free, flame-retardant composition according to claim 1, wherein the at least one halogen-free thermoplastic base resin is selected from the group consisting of polyethylene, ethylene vinyl acetate (EVA), and ethylene propylene diene monomer rubber (EPDM).

3. Halogen-free, flame-retardant composition according to claim 1 or 2, wherein the proportion of the at least one halogen-free thermoplastic base resin (i) in the total amount of the halogen-free, flame-retardant composition is 15–50 wt.%.

4. Halogen-free, flame-retardant composition according to any one of the preceding claims, wherein the at least one metal hydroxide is a flame-retardant metal hydroxide.

5. Halogen-free, flame-retardant composition according to claim 4, wherein the flame-retardant metal hydroxide is selected from the group consisting of aluminum hydroxide, magnesium hydroxide, and calcium hydroxide. 6.Halogen-free, flame-retardant composition according to any one of the preceding claims, wherein the proportion of the at least one metal hydroxide (ii) in the total amount of the halogen-free, flame-retardant composition is 40-75 wt.%.

7. Halogen-free, flame-retardant composition according to any one of the preceding claims, wherein R. 1 -CH=CH2.

8. Halogen-free, flame-retardant composition according to any one of the preceding claims, wherein R 2 represents an alkyl group that may be substituted and / or comprises at least one heteroatom. WA12410S / WI 16 9. Halogen-free, flame-retardant composition according to any one of the preceding claims, wherein R 210. Halogen-free, flame-retardant composition according to any one of the preceding claims, wherein the proportion of the at least one silane (iii) in the total amount of the halogen-free, flame-retardant composition is 0.1–2% by weight.

11. Halogen-free, flame-retardant composition according to any one of the preceding claims, wherein the excipient is an initiator.

12. Halogen-free, flame-retardant composition according to any one of the preceding claims, wherein the proportion of the at least one excipient (iv) in the total amount of the halogen-free, flame-retardant composition is 0.2–1.5% by weight.

13. Cable comprising the halogen-free, flame-retardant composition according to any one of the preceding claims.