Stock material or miscellaneous articles – Composite – Of silicon containing
Reexamination Certificate
2000-06-26
2002-06-11
Dawson, Robert (Department: 1712)
Stock material or miscellaneous articles
Composite
Of silicon containing
C428S500000, C428S484100, C524S506000
Reexamination Certificate
active
06403228
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to the use of functional organylorganyloxysilanes on a carrier in cable compounds which comprise certain thermoplastic base polymers, and also fillers. The invention further relates to the cable compounds as such, to cables with sheathings made from these cable compounds and a method of sheathing cable.
2. Discussion of the Background
Cable compounds is the term used for mixtures of substances which comprise a base polymer and also mineral (or inorganic) reinforcing, extending or flame-retardant fillers and are used to provide metallic conductors with an electrically insulating sheathing. It is known that adding functional organylorganyloxysilanes facilitates the dispersion of the filler in the base polymer and improves the adhesion between base polymer and filler. In this context organylorganyloxysilanes are silanes which carry, bonded via a carbon atom to the silicon atom, an organic radical which in turn contains a functional group. The easier dispersion and the improved adhesion could be attributable to hydrophobicization of the surface of the filler particles by the silane. Improved adhesion gives the cable sheathing better mechanical properties.
EP O 518 057 B1, for example, discloses liquid mixtures made from linear and cyclic siloxanes and, respectively, siloxane oligomers containing vinyl groups, and the use of these as crosslinking agents in cable compositions, e.g. for high-pressure polyethylene. However, liquid additives pose problems for the user since the usual equipment for weighing and feeding small amounts of additives is designed only for solids. Minor liquid components therefore have to be weighed out and fed manually. This generally increases costs and is an additional source of error.
A solution to this problem is to bind liquid functional organosilanes to highly adsorbent or highly absorbent solids, which can then be easily weighed out and fed as “dry liquids” using the usual equipment. For example, DE 195 03 779 A1 describes a combination of silica and transpolyoctenamer as a carrier for liquid rubber chemicals, including vinyl- and mercaptosilanes, and also sulfur silanes. DE 44 35 311 A1 describes materials called reinforcing additives, made from oligomeric and/or polymeric sulfur-containing organylorganyloxysilanes and from a carrier which is semi-activated, activated and/or highly activated carbon black. These are suitable for use in rubber mixtures or rubber compositions, and also plastics mixtures. In both of the texts mentioned, however, there is no mention of cable compounds. EP 0428 073 B 1 discloses a process in which (i) a base polymer, (ii) a spongy polymer or a swellable polymer in which a (meth)acryloxy-functional organosilane is present and (iii) a free-radical generator are mixed and the mixture melted and homogenized. This process, too, is not oriented toward the use of the homogenized mixtures for cable compounds. However, it is stated in WO 97/07165 that the solid mixtures described there, made from functional organosilanes and certain large-surface-area silicas having low surface energy, can be used, inter alla, for insulating wires and cables.
SUMMARY OF THE INVENTION
One of the subject matters of the present invention is a method of preparing cable compound comprising mixing (1) a liquid functional organylorganyloxysilane bound to a carrier, or of a liquid (co)condensate derived from a functional organylorganyloxysilane and bound to a carrier; (2) a thermoplastic base polymer which having polar functional groups; and (3) a reinforcing or extending mineral filler.
Another subject matter of the invention is cable compounds which comprise (1) a liquid functional organylorganyloxysilane bound to a carrier, or a liquid (co)condensate derived from a functional organylorganyloxysilane and bound to a carrier, (2) a thermoplastic base polymer having polar functional groups and (3) a reinforcing, extending or flame-retardant mineral filler.
A further subject matter of the invention is cables whose metallic conductors have been sheathed by a cable compound of this type.
A further subject matter of the invention is a method of sheathing cable comprising applying a surface layer of cable compound on the surface of a cable.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Functional Organylorganyloxysilanes:
For the purposes of the invention, functional organylorganyloxysilanes comprise, bonded via a carbon atom to a silicon atom, at least one organic radical (organyl radical), such as a straight-chain or branched alkylene radical having from 2 to 6 carbon atoms and carrying at least one functional group. The functional group may, for example, be a hydroxyl, nitrile, carbonyl, carboxyl, acyl, acyloxy, carboalkoxy, mercapto, sulfane (X
x
) or epoxy group or an amino group, if desired substituted by one or two hydrocarbon radicals having from 1 to 6 carbon atoms, or else a halogen atom, in particular a chlorine atom, or an olefinic double bond or a C—C triple bond. The organic radical may also contain two or more identical or different functional groups, e.g. two amino groups or an acyl radical having an olefinic double bond, for example the (meth)acryloxy radical. The functional organylorganyloxysilanes secondly contain at least one hydrolyzable radical, preferably three hydrolyzable radicals, e.g. one or more alkoxy or alkoxyalkoxy radicals having in each case from 1 to 6 carbon atoms. The functional organylorganyloxysilanes may moreover contain one or two other nonfunctional and nonhydrolyzable radicals, e.g. a hydrocarbon radical having up to 8 carbon atoms, for example methyl, propyl or n-hexyl.
Examples of suitable functional organylorganyloxysilanes are vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(2-methoxyethoxy)silane, 3-mercaptopropyltrimethoxysilane, 3-glycidyloxypropyltrimethoxysilane, 3-glycidyloxypropyltriethoxysilane, 3-methacryloxypropyltrimethoxysilane, and 3-ethacryloxypropyltris(2-methoxyethoxy)silane. Preferred functional organylorganyloxysilanes are aminoorganylorganyloxysilanes, if desired N-substituted by one or two alkyl radicals each having from 1 to 6 carbon atoms, since the sheathings made from the corresponding compounds have excellent mechanical properties (such as tensile strength, elongation at break, ultimate tensile strength and modulus of elasticity) and electrical properties (such a electrical dissipation factor and dielectric constant). Among the suitable aminoorganylorganyloxysilanes mention may be made, for example, of 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyl-diethoxysilane, N-aminoethyl-3-aminopropyltrimethoxysilane, triamino-functional propyltrimethoxysilane (N-trimethoxysilylpropyldiethylenetriamine, also termed DYNASYLAN® TRIAMO) and (N′-aminoethyl)-N-aminoethyl-3-aminopropylsilane.
Instead of a functional organylorganyloxysilane a mixture made from one or more of these substances may be used. According to the invention use may also be successfully made of (co)condensates of the functional organylorganyloxysilanes having weight-average molecular weights of up to about 10,000. These are understood to be condensates (or oligomers) of the functional organylorganyloxysilanes and, respectively, cocondensates of these substances with other, nonfunctional organylorganyloxysilanes or with organyloxysilanes. Among these mention may be made, for example, of methyltrimethoxysilane, methyltriethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, isobutyltrimethoxysilane, isobutyltriethoxysilane, octyltriethoxysilane, hexadecyltrimethoxysilane and tetraethoxysilane. The (co)condensates are prepared, for example, in a known manner by hydrolysis and, respectively, cohydrolysis of the silanes with limited amounts of water, followed by condensation of the silanols. In the cocondensates the proportion of the (amino)functional organylorganyloxysilanes should be at least 10% by weight, advantageously at least 50% by weight.
Instead of a cocondensate it is also possible to use the funct
Barfurth Dieter
Edelmann Roland
Frings Albert-Johannes
Horn Michael
Jenkner Peter
Dawson Robert
Degussa - AG
Feely Michael J
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