Stock material or miscellaneous articles – Coated or structually defined flake – particle – cell – strand,... – Rod – strand – filament or fiber
Reexamination Certificate
1998-07-28
2001-06-05
Weisberger, Richard (Department: 2164)
Stock material or miscellaneous articles
Coated or structually defined flake, particle, cell, strand,...
Rod, strand, filament or fiber
C428S357000, C428S361000, C428S387000, C556S438000, C556S420000
Reexamination Certificate
active
06242096
ABSTRACT:
The invention relates to varnished metal wires upon which there are applied one or more electrically insulated varnish coatings. Such varnish-insulated wires, which in particular consist of copper, have been used for a long time for the manufacture of windings of electrical motors and other coils. The applied varnish coating in this case, in addition to providing protection against mechanical influences, is also intended to have an insulating effect. The varnish layer, or a plurality of varnish layers to be applied one above the other, are applied with applicator systems specially developed for this purpose, the solvent contained in the varnish being removed by a thermal treatment. In this thermal treatment at the same time the organic resins are hardened by polycondensation. The polymer systems used until now on a polyimide or polyamide basis are however not always suitable to resist the mechanical stresses occurring, such in particular as occur during winding of coils or other elements.
Improved scratch resistance and adhesion and a greater resistance to scraping stress and thus higher abrasion resistance are required.
The coated metal wires must also however be sufficiently flexible with the coating applied, and the coating must not crack during bending and the corresponding partial stretching along the bending radius. A high partial discharge stability is also an important criterion.
Moreover, the applied varnish layers or plurality of varnish layers applied one above the other must also have the desired properties even at relatively high temperatures, and no harmful materials must be given off during heating.
In order to reduce costs during the manufacture of such varnished metal wires, high hardening speeds must be achieved in order to shorten the necessary coating and in order to keep small the necessary outlay on space for the coating systems. From the environmental point of view it is also necessary to use coating materials which contain no solvents or non-toxic and non-aggressive solvents.
It is therefore the object of the invention to provide varnished metal wires with one or a plurality of electrically insulating varnish coatings, ensuring a high hardening speed with simultaneous improvement in the mechanical, thermal and electrical properties of the applied varnish coatings.
In contrast to those previously used, the electrically insulating varnish layers applied according to the invention contain no critical solvents, such as xylols, cresols, NMP or others, so that during coating and during hardening there are no further requirements as regards an expensive evacuation system and filtering of the evacuated gases. As in the case of the varnish layers applied, as a rule the organically polymerisable groups are compounded with the inorganic polymer structure, no toxicologically problematic monomers such for example as acrylate monomers, occur.
The coating may be extremely flexible in structure by means of various methods; they may be applied for example by extrusion with high productivity and the smallest losses. In one coating step, considerably larger coating thicknesses can be applied than is possible with previous methods and wire varnishes previously used. Thus, in one coating procedure, a coating thickness can be applied which previously was only achieved with ten successively applied coats. The coating thickness should be in a range between 2 and 100 &mgr;m and preferably between 5 and 30 &mgr;m.
The most varied methods and energies may be used for hardening; thus hardening may be carried out for example with UV, IR, normal light or thermal procedures, or with the combination of a plurality of energy forms. As the hardening speeds of the IR or photo-induced hardening lie considerably above the thermal ones, the corresponding varnish systems are preferred. In this way in all there results a higher application speed.
A further advantage is the great variability in the composition of the varnish layer, which can be co-ordinated to the most varied mechanical requirements and correspondingly optimised. Thus, for the most varied cases of application, the abrasion resistance, scratch resistance, hardness, flexibility, tensile strength, adhesion and expansion capacity can be correspondingly optimised for all or special properties.
A further advantage arises from the achievement of a relatively high overall cross linking density, which ensures high tan &dgr;-transition temperatures and the inorganic molecule portion ensures a high partial discharge stability, such as for example are necessary with electric motors.
The electrical properties are also favourable, as high disruptive strengths and high volume resistances can be achieved with the applied varnish layers.
The varnished metal wires according to the invention are considerably improved in their properties compared to the previously-used varnish layers, as in particular normally mutually exclusive requirements, such for example as high scratch resistance (scraping resistance) and a high tensile strength or expansion capacity cannot normally be optimally taken into account within wide temperature ranges.
In addition, one or more layers of other materials or mixtures of materials can be applied.
The coating may be applied to the most varied metal, such as copper, gold, silver, aluminum, tin, zinc or iron or alloys.
The varnished metal wire according to the invention will be coated with a varnish which has been obtained by partial or total hydrolytic condensation of one or a plurality of hydrolytically condensable compounds of silicon and if necessary other elements from the group B, Al, P, Sn, Pb, the transitional metals, the lanthanides and the actinides, and/or from the precondensates derived from the abovenamed compounds, if necessary in the presence of a catalyst and/or of a solvent by the action of water or moisture. This varnish can be applied to metal wires, which if necessary already have one or more electrically insulating varnish coats, and can if necessary be subsequently dried and hardened.
It is advantageous to apply at least two varnish layers, which represent an organically modified silicic acid (hetero) polycondensate.
The organically modified silicic acid (hetero) polycondensate to be used according to the invention can contain one or more hydrolytically (pre)-condensed compounds of silicon, which are derived from various monomers. These coating materials are known under the name ORMOCERs. Express reference is made here to the disclosed content of U.S. Pat. No. 5,399,738; 5,532,398; 5917,075; and 6,124,491.
Examples of such monomers, which are derivable from general formulae, are:
I.
{X
a
R
b
Si[(R′A)
c
]
(4−a−b)
}
x
B (I)
The residues and indices being identical or different, and having the following meaning:
A =
O, S, PR″, POR″, NHC(O)O or NHC(O)NR″,
B =
a straight-chained or branched organic residue,
derived from a compound BI with at least one (for
c = 1 und A = NHC(O)O or NHC(O)NR″) or atleast
two C = C-double bonds and 5 to 50 carbon atoms,
R =
alkyl, alkenyl, aryl, alkylaryl or
arylalkyl,
R′ =
alkylene, arylene or alkylenarylene,
R″ =
hydrogen, alkyl or aryl,
X =
hydrogen, halogen, hydroxy, alkoxy, acyloxy,
alkylcarbonyl, alkoxycarbonyl or NR″
2
,
a =
1, 2 or 3,
b =
0, 1 or 2,
c =
0 or 1,
x =
a whole number, whose maximum value corresponds
to the number of double bonds in the compound B′
minus 1, or is equal to the number of double
bonds in the compound B′, if c = 1 and A stands
for NHC(O)O or NHC(O)NR″,
the alkyl or alkenyl residues if necessary being substituted straight-chained, branched or cyclic residues with 1 to 20 carbon atoms and being capable of containing oxygen and/or sulphur atoms and/or amino groups, aryl stands for if necessary substituted phenyl, naphthyl or biphenyl, and the above alkoxy-, acyloxy-, alkylcarbonyl-, alkoxycarbonyl-, alkylaryl-, arylalkyl-, arylene-, alkylen
Deichmann Karl
Storch Werner
Wolter Herbert
Brinks Hofer Gilson & Lione
Fraunhofer Gesellschaftzur Forderung der Angewandten Forsch{over
Weisberger Richard
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