JOHANSSON LENNART (SE)
SCHUETTE TORSTEN (SE)
DAHLUND MATS (SE)
JOHANSSON LENNART (SE)
SCHUETTE TORSTEN (SE)
| DE4207246A1 | 1993-09-09 | |||
| EP0544513A1 | 1993-06-02 |
J. AM. CHEM. SOC., Volume 115, 1993, SIMON H. FRIEDMAN et al., "Inhibition of the HIV-1 Protease by Fullerene Derivatives: Model Building Studies and Experimental Verification", page 6506 - page 6509.
| 1. | A method of protecting organic materials such as oils, fats and polymeric materials, which are subjected to oxida tion or other degrading influence as a result of the influ¬ ence of external factors such as heat or other radiation as well as electric or magnetic fields, whereby means counter¬ acting the breakdown are added, characterized in that essentially globular or tubular carbon molecules, socalled fullerenes, or derivatives based on said carbon molecules are added to the organic material. |
| 2. | A method according to claim 1, characterized in that said essentially globular or tubular carbon molecules are mixed to a content of between 0.01 and 15 per cent by weight in an organic material to counteract the breakdown by oxidation or other degrading influence. |
| 3. | A method according to claim 2, characterized in that said essentially globular or tubular carbon molecules are mixed to a content of between 0.1 and 7 per cent by weight. |
| 4. | A method according to claim 1, characterized in that said essentially globular or tubular carbon molecules are incorporated and bonded chemically to a polymer material. |
| 5. | A method according to claim 4, characterized in that said essentially globular or tubular carbon molecules are incorporated in the polymer material by incorporating two carbon atoms, included in the carbon molecule, into a polymer chain included in the polymer material. |
| 6. | A method according to claim 4, characterized in that said essentially globular or tubular carbon molecules are in corporated into the polymer material by connecting together a plurality of carbon atoms, included in the carbon molecule, by a crosslinking reaction into a plurality of polymer chains to bond these together in a network. |
TECHNICAL FIELD
The invention relates to a method of protecting organic materials, such as polymer materials, fats and oils, against breakdown, preferably breakdown as a result of oxidation and/or partial discharge.
BACKGROUND ART
Organic materials such as polymeric materials, fats and oils are affected by external factors such as oxygen, heat or other radiation as well as electric or magnetic fields, whereby chemical changes such as crosslinking, chain scissoring, the occurrence of double bonds, gas evolution and oxidation arise. To withstand these breakdown mechanisms, organic materials are often stabilized by additives such as voltage stabilizers and antioxidation agents (antioxidants) .
Oxidative breakdown of organic materials can be initiated and propagate by means of radicals which are formed or supplied by the influence of the above-mentioned factors. To counter¬ act this breakdown, one or more antioxidants are added. By antioxidants, or radical scavengers, are meant in this appli¬ cation additives which react with the radicals and thereby terminate the degrading chain reactions.
By voltage stabilizers, or energy scavengers, are meant in this application additives which protect organic materials against breakdown by capturing electrons, which function as carriers of energy in a field of force acting on the polymer.
SUMMARY OF THE INVENTION
Organic materials such as oils, fats and polymeric materials, which are exposed to oxidation or other degrading influence from external factors such a heat or other radiation as well as electric or magnetic fields, are protected against break¬ down by adding a counteracting agent in the form of anti¬ oxidants, voltage stabilizers, etc., to the material.
According to the invention, a greatly increased protection against breakdown of organic materials is obtained by adding globular or tubular carbon molecules, so-called fullerenes, or derivatives based on these carbon molecules, to the organic material. According to the invention, the fullerene molecules are intermixed to a content amounting to between 0.01 and 15 per cent by weight, preferably to a content of between 0.1 and 7 per cent by weight.
The added carbon molecules prevent breakdown of the organic material by capturing and rendering harmless free radicals as well as electrons which, through the external influence, have been added or formed in the organic material.
In one embodiment of the invention, the above-mentioned globular or tubular carbon molecules are mixed into an organic material such as an oil, a fat or into a polymer material to counteract breakdown in connection with thermal, electric, or magnetic load, or an external influence as a result of light or other radiation.
A polymer material which has been protected against breakdown by intermixing globular or tubular carbon molecules according to the invention is of great value as an insulator in elec¬ trical installations by constituting protection, in addition to the enhanced protection against breakdown by the above- mentioned carbon molecules capturing and taking care of free
radicals and electrons, also against breakdown of 'the polymer material arising from electric breakdowns, so-called partial discharge. The partial discharge resistance is obtained, during partial discharge, by carbon molecules included in the polymer material being exposed, whereby these carbon mole¬ cules, because of their lower resistivity and thermal conduc¬ tivity in relation to the polymer material, spread the elec¬ tric and thermal load from the partial discharge impulse over a large area such that the partial discharge is reduced in an effective way and the damage is limited instead of growing.
In another embodiment of the invention, the above-mentioned globular or tubular carbon molecules are incorporated into a polymer material and chemically bonded to the polymer. When these globular or tubular carbon molecules are incorporated and chemically bonded to a polymer material, the protecting carbon molecules are retained in the polymer material and cannot migrate out of the same. If this is limited to one bond only between the carbon molecule and a polymer chain, the carbon molecule will terminate the chain. When two carbon atoms included in the carbon molecule are bonded to a polymer chain, the carbon molecule will be bonded into the polymer chain; if instead the two carbon atoms are each bonded to a polymer chain, the carbon molecule will bond these polymer chains together.
By bonding more than one of the carbon atoms included in the carbon molecule to more than one polymer chain, a cross- linking is achieved which, in addition to increasing the breakdown resistance, connects the polymer molecules together into strong networks. These crosslinked networks change the polymer material and above all its mechanical properties, primarily in the form of an increase of the stiffness of the polymer material.
EXAMPLE 1
Transformer oil
Essentially globular carbon molecules containing 60 carbon atoms, Ceo were mixed in a weight ratio of 1:50 with an excess of dodecylamine and were allowed to react under stirring and supply of heat. The adduct thus obtained was separated from the reactants and was mixed into a transformer oil to a content of 0.5 per cent by weight.
A transformer oil according to this example exhibits an increased resistance to oxidative breakdown and breakdown as a result of electric load.
EXAMPLE 2
Insulation fluid
Cδo molecules were mixed to a content of 0.1 per cent by weight into toluene, whereby an insulator fluid was obtained which exhibits an increased resistance to oxidative breakdown and breakdown as a result of electric load.
EXAMPLE 3
Lubricating grease
An adduct was prepared by analogy with Example 1 based on C 60 molecules and dodecylamine and was mixed to a content of 0.5 per cent by weight into a lubricating grease consisting of mineral oil and a thickening agent in the form of a lithium soap.
A lubricating grease according to this Example exhibits an increased resistance to oxidative breakdown, especially at elevated temperature.
EXAMPLE 4
Crosslinked polyurethane
C 6 o was reacted with a 10 per cent bromine solution in carbon disulphide at room temperature under stirring, whereby CβoBrβ was formed and was precipitated in the form of crystals. Bromine fullerene was separated from the reactants and was mixed with an excess of 1.2-ethane diol. This led to the formation of C δ o (OCH 2 CH 2 θH) n where n<8. Any remaining bromine substituents were removed by heating to 150°C.
The C 6 o(OCH 2 CH 2 θH) n obtained was mixed in castor oil to a content of 5 per cent by weight. This mixture was reacted with a diisocyanate, methylene diphenyl isocyanate, whereby a crosslinked polyurethane with a fullerene content of 3.3 per cent by weight was obtained.
A crosslinked polyurethane according to this Example has the fullerene molecules incorporated in the polymer chains where- by isocyanate groups from a plurality of diisocyanate mole¬ cules are bonded to the same fullerene molecule. This cross- linking gives a very stiff polyurethane material.
EXAMPLE 5
Insulating wire enamel
Cgo molecules were mixed to a content of 5 per cent in an epoxy resin resin intended to be applied as an insulating layer onto an electric conductor.
An electrical insulation in the form of an insulating varnish according to the invention exhibits an increased resistance to oxidative breakdown as a result of electric load or other external factors.
EXAMPLE 6
Semiconducting polyethylene
A powder consisting of Cgo molecules was mixed with carbon black to a content of 6 per cent by weight. The fullerene- containing carbon black mixture was mixed in HD polyethylene, was kneaded and rolled into a homogeneous compound with a composition of
3 per cent by weight fullerene
47 per cent by weight carbon black
50 per cent by weight HD polyethylene
A semiconducting polymer material with a positive temperature coefficient prepared according to this example exhibits an increased resistance to breakdown relative to conventional polymeric PTC materials.
EXAMPLE 7
Semiconducting copolymers
A powder consisting of C 6 o molecules was mixed with carbon black to a content of 10 per cent by weight. The fullerene- containing carbon black mixture was added to a copolymer of LD polyethylene, LD-PE, and ethylenebutyl acrylate, EBA, was kneaded and rolled into a homogeneous compound with a compo¬ sition of
5 per cent by weight fullerene
45 per cent by weight carbon black
50 per cent by weight of a copolymer of LD-PE and EBA.
A semiconducting copolymer prepared according to this Example and included as a screen in an insulating system around an electric conductor exhibits an increased resistance to oxida¬ tive breakdown as a result of electric load or other external factors.
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