FR2576545A1 - METHOD FOR MANUFACTURING A SOFT ELECTRICAL INSULATING MATERIAL AND SOFT ELECTRICAL INSULATING MATERIAL OBTAINED BY THIS METHOD - Google Patents

Abstract

1. Process for the manufacture of a flexible electrical insulating material, said process consisting of applying to a flexible support a resin charged with mineral charges made up of a finely divided mineral powder of granulometry less than 40 mu m, with the object of improving the thermal and dielectrical properties of the latter, the resin prior to application being formed by a complex obtained by mixing an organic bonding material and the mineral powder, and applying the resin to the support by means of induction, the entity constituted by the support coated in resin, following application of the resin to the support, being hot-polymerised, said hot polymerisation being carried out at stages of temperature between 100 degrees C and 200 degrees C.

Description

The present invention relates to a

  flexible electrical insulating material and its method of

  brication, the aforementioned material being more especially adapted for its performance in use in the field of the construction of electrical machines

  and in electro-mechanics in general.

  In the technical field of construction

  electrical or electro-mechanical use is currently

  flexible insulators intended to ensure the isolation of

  of inserted conductors or groups of conductors

  in the notches of the pole pieces of the tour machines

  in particular, these flexible sheet-shaped insulators

  the ribbons or appropriate size ribbons being for example intended to ensure the separation and isolation of groups of conductors constituting each a phase

  winding of the motor or the rotating machine.

  Among the flexible insulators used to date, so-called complex products are known comprising a support, generally a polyester film, on the faces

  from which are deposited polyester felts, pa-

  calendered or not, such as aromatic polyamides, or mats such as glass mats or glass fabric all possibly being impregnated with a resin by varnishing.

  Other flexible, insulating materials are

  stencilled from a support, usually a polyester film, varnished with an organic resin, ec are

  especially used to actually allow the thermosou-

supportability.

  Materials of the first category that are normally commercially available have

  particular the subject of a description, in relation to

  their method of implementation, in the patent of

  n ° 881 120 filed in France on December 6, 1961.

  Some of the materials described above have the following drawbacks: 5. poor resistance to many chemical agents or solvents impregnating varnishes

  used during the impregnation of the elec-

  motors because of complex cleavages

  particularly obtained by laminating or dissolving

varnishing resin,

  moisture absorption of the counter layers

  bonded sometimes much higher than that of the support, surface dielectric properties of these sometimes mediocre materials leading in particular,

  modest performance in terms of risk

  than bypassing the insulating material in

  severe use, low calorie

this type of material.

  The present invention overcomes the aforementioned drawbacks by implementing a method of manufacturing a material and a material

  whose performance is significantly improved.

  The process for producing an insulating material

  flexible electrical lant is to deposit on a

  flexible port a resin loaded with mineral charges

  to improve thermal properties

and dielectrics of the latter.

  The flexible electrical insulating material thus obtained comprises a central core, or flexible support, and a coating of the central core formed by a resin layer consisting of an organic material loaded with

a mineral powder.

  The invention finds application in the field of electrical or electro-mechanical construction, but also in the field of the construction of electronic devices, especially in industrial electronics. The invention will be better understood when reading

  the description and the observation of the drawings below

  in which: - Figure 1 shows a general arrangement

  illustrative of the different phases of the process of

  Figure 2 shows respectively 2a,

  2b a sectional view of a film of electrically insulating material

  invention and an enlarged view of a portion

of this cup.

  The method for manufacturing a flexible electrical insulating material of the invention will firstly be described by means of FIG. 1. This process consists in depositing on a flexible support a resin loaded with mineral fillers in order to improve the properties

  thermal and dielectric of the latter. On the

  1, the method, in a non-limiting manner, is represented in the form of a continuous manufacturing process. The flexible support S constituted in the form of a feed roller A and formed according to a strip

  is traditionally engaged in a set of

  trailing constituted by RE drive rollers and RG guide rollers. Throughout the path of the strip constituting the support, different

  positions are planned to enable the achievement of

  the various steps of the process, hereinafter explained.

  In order to ensure perfect adhesion of the

  resin loaded on the support S, the support is, previously,

  deposition of the resin, treated in such a way as to

  make the faces of the support sufficiently rough.

  In FIG. 1, this treatment is denoted T. This treatment may be, for example, a mechanical treatment or an electrical treatment. An electrical treatment will however be preferred to a mechanical treatment. In

  the case of an electrical treatment, the actual treatment

  killed is a CORONA treatment like treatment.

  The voltage applied to the treatment electrodes

  CORONA effect, is determined by the thickness

  support S or band, and depending on the speed

  scrolling of it. Advantageously, the

  thickness of the support is determined according to the nature of it. In the case of a support constituted

  by a plastic material such as a polyester (poly-

  ethylene glycol terephthalate), the thickness e of the

  port can be between 23 im and 350 mm.

  By way of non-limiting example, other materials

  can be used to build the support.

  Thus, it may be constituted by a glass fabric with a thickness e of between 5/100 mm and / 100 mm, the production of a fabric support of

  glass allowing an improvement of the mechanical properties

  of the final material, with regard to the resistance

aging.

  The support may also be constituted by an aromatic polyamide paper normally available commercially. In this case, the thickness of the paper can be chosen between 5/100 mm and 13/100 mm

for example.

  The support S can also be constituted by

  a material of the commercial fluoropolymer film type

  made by the company iO0ECIST under reference L 601.

  The thickness of the support in the latter case can be taken between limits ranging from 50 gm to 100 Nm. This latter material, because of its better temperature resistance, 170 C continuously, can be chosen for the realization of a flexible insulating material

improved temperature resistance.

  After mechanical or electrical treatment

  mentioned, the tape is directed towards a set of

  duction noted E for depositing the resin on the suprort. Prior to the deposit itself, the resin is formed by a complex obtained by mixing an organic binder material and a mineral powder. By way of non-limiting example, the organic material consists of a polymerizable material based on acrylic material, polyurethane, epoxides

or silicone.

  The mineral powder is preferably fine

  divided, and with a particle size of less than 40 Nm.

  The grain size values mentioned above allow a

  better homogeneity of the final material. Mineral powder

  Rale may be constituted by mica powder which has the advantage of not causing absorption phenomena of the constituent products of the resin, a phenomenon always detrimental to the mechanical and ultimately electrical properties of the insulating material. The mica powder can however be replaced

  by glass beads of the same particle size.

  Coupling agents may further be added to the organic resin to allow

  perfect connection between it and the

  ral. The coupling agents may be silanes, carbon-based silicon derivatives, and provide a better bond between the grains of the

mineral powder and resin.

  The resin can be advantageously but not necessarily prepared from a solvent

  consisting for example of aromatic hydrocarbons

  c. The resin, a polyurethane resin for example, is first dissolved in the solvent. The agents

  previously mentioned coupling mechanisms are added to the

  tion. Finally, the mineral load is added to

  ble, the resin being ready for application on the

  Harbor. By way of non-limiting example, for a quantity

  one part by weight of solvent, a quantity of polyurethane resin

  between 80 and 30% of the weight of the solvent will be dissolved in the solvent and a complementary amount of mineral powder such as mica,

  and 70% by weight of solvent, will then be added.

  It has thus been found during the tests of

  insulation materials of the invention that the choice of percentages by weight of resin and powder

  mineral was used to influence the properties of

  caniques and thermiques of the final material obtained. Thus, the increase in percentage of mineral powder, such as mica, has the effect of increasing the rigidity of

  all. The decrease in the percentage of min-

  has the effect of increasing flexibility

of the final material.

  After the aforementioned preparations, the filled resin is ready to be deposited on the faces of the support. As shown in FIG. 1, the previously prepared resin is introduced into the coating assembly referenced E so as to form a bath

  wherein the carrier strip is inserted

  picked and moved. The deposit of the filled resin is thus carried out by coating. This deposit can also

  without inconvenience be made more

  by projection or by means of a doctor blade. In the embodiment of the method shown in FIG. 1, the strip on which the loaded resin has been deposited by passing through the bath, is then introduced into a die referenced F. The die F makes it possible to determine the thickness of the charged resin which will be

  actually kept on each side of the band.

  By way of non-limiting example, this thickness for

  each face can be equal to 50 gm and

  advantageously between 20 Am and 200 dm.

  It has also been found that the final thickness of the charged resin layer applied to

  the faces of the strip, determines the properties of the

  of the final material. The support being

  generally, particularly when it is con-

  with polyester, stiffer than the filled resin, the thickness of the resin layers

  applied on the faces of the support will be chosen

  ble, that is to say in the vicinity of the value of 20 gm above, when the final material is intended for

  applications in which an insulation more

  gide is wanted. On the contrary, the thickness of the charged resin layers applied on the faces of the support will be chosen in the vicinity of the upper limit value of 200 dm, when the final material will be intended for applications in which a more flexible insulator is sought. The support S provided with its coated resin coating, of appropriate thickness on each of its faces,

  is then heat-cured in a set of poly-

  merification noted P in Figure 1. The set of polymers

  P is for example constituted by a set

  modular, each of the modules being capable of

  ter and maintain a determined portion of band at a predetermined temperature for a specified time, depending on the speed of travel of the band. AT

  As an exemplary embodiment, the first module

  wear the resin-coated tape at a temperature of

  The successive sets allow, in successive stages of temperature of the order of C, to bring the band at a final module at a temperature of the order of 2000C. During the polymerization, the solvent present in the coating layers, when this solvent has been used, is removed by evaporation at the first polymerization module. The strip provided with its charged resin coating is then gradually raised in steps of 20 ° C., at the temperature of 180 ° C. at which the polymerization proper is begun.

  the last being completed in the fihal module at the temperature

  The final material can be conditioned after cooling in the form of a storage roll, referenced ST in FIG. 1. The gradual rise in temperature of the polymerization phase makes it possible to avoid the bubbling phenomenon. that is, the creation of gas bubbles within the insulating material itself. The actual polymerization makes the thermoset resin, which in the final material is resistant to the impregnating varnishes used in the construction of electromechanical motors or machines.

  and resistance to the warming up of those

  during their operation. By way of non-limiting example, the holding time of the strip coated with resin layer of thickness 50 gm per face at the temperature of 200 C at the last polymerization module, is of the order of 1 minute for a speed

bandwidth of 5 m / min.

  The flexible electrical insulating material of the in-

  vention will now be described by means of the figures

  2a and 2b. As shown in FIG. 2a, the material

  made in the form of a film has a central core

  trale 1 or flexible support. Of course, the material

  can also be produced in the form of leaves that is

  that is to say band of sufficient width, the band then being cut into sheets or pieces of various shapes. A coating of the central core 1 is formed by a top and bottom layer 2 of resin 3 constituted by the loaded organic material or materials

  with a mineral powder as described above.

  The central core 1 consists of a plastic material

  such as polyester (ethylene glycol polytephthalate) or glass fabric, aromatic polyamide or fluoropolymer material. The upper 2 and lower 3 layers consist of an organic material such as a polymerizable material based on acrylic material, polyurethane, epoxides or silicone. The upper and lower layers 2 and 3 having inclusions formed by the mineral powder, which consists of

  mica powder or granulated glass beads

  In addition, as shown in FIG. 2b, the inclusions 20 of the upper layer 2 or the inclusions 30 of the lower layer 3 are surrounded by a thin layer formed by

  the liaison agent ensuring the coupling between the material

  organic matter and the mineral powder. The thin layer

  21 is a monomolecular or substantially mono-

  molecular, formed on the whole surface of the grain, forming inclusion, and lining this one. The thin layer formed at each inclusion by the agent

  binding, prevents foreign chemicals from

  can be introduced into the interstices

  always exist between the grains of the powder

mineral and resin.

  The upper and lower layers 2 and 3 thus make it possible to protect the support constituted by

  example by a polyester film of the achievement of the

  and thus allow to increase the life of the support and the final material. As an example, an aging test known as a test

  the curved electrode was made under the conditions

  specified in the note edited by the Elec-

  international tro-technique, under the reference 370 year 1971. This test performed on a final material comprising a support of the polyester film type allowed

  to observe a much higher temperature resistance

  greater than 145 C of the final material over a period of

  continuously, 20 000 hours, whereas under conditions

  similar test conditions, the temperature resistance of the

bare polyester does not exceed 130 C.

  In addition, various types of materials made

  by the method of the invention, allow a better

  their evacuation of calories, due to the presence

  in the resin mineral charges.

  In addition, a significant improvement

  the surface dielectric properties of the material

  final aspect of the invention. Samples of the differences

  materials made according to the process previously

  described, have been subjected to a test of resistance to

  electrically, that is to say has a contour test-

  insulation, consisting of sheets, by streamlines. All things being equal, it has been observed, compared to the insulating materials

  flexible of the prior art obtained against

  bonding, that the electrical voltages needed to cause the bypass were significantly higher than the voltages provoking, under the same conditions, the circumvention of the materials of the art

  prior. This improvement of the properties

  surface area of the flexible insulating material

  the invention is due to the presence of

  in the resin, which causes an increase in

  significant degree of resistance to electrical tracking.

Claims (15)

  1. Method of manufacturing an insulating material   flexible electrical system, characterized in that it consists of   Use a flexible support with a resin loaded with mineral charts in order to improve the thermal and dielectric properties of the latter. 2. Method according to claim 1, characterized in that the support is, prior to the filing of the resin, electrically treated.   3. Method according to claim 1, characterized in that the support is prior to the deposit of the mechanically treated resin.   4. Method according to one of claims I to 3,   characterized in that prior to depositing the resin   is formed by a complex obtained by mixing a material   organic binder and a mineral powder.   5. Method according to claim 4, characterized   in that the mineral powder is finely divided, nullomerism less than 40.m.   6. Process according to claim 5, characterized   in that coupling agents are added to the organic resin to enable perfect bonding   between it and the mineral charges.   7. Process according to one of the preceding claims   cedeentes, characterized in that the deposition of the resin   on the backing is done by coating.   8. Process according to claim 7, characterized   rised in that, following the deposition of the resin on the sup-   port, the assembly constituted by the support coated with resin is heat cured.   9. The method of claim 8, characterized   in that said hot polymerization is effected   killed gradually in increments of temperature between 1000C and 200C.   10. Process according to one of the preceding claims   characterized in that the choice of the nature, the deposited resin, the mineral powder charge rate, the thickness of the deposit, the polymerization temperature variations and the polymerization time is carried out in order to obtain a degree of variable flexibility of the final product for various uses of it.   11. Electrical insulating material, flexible,   characterized in that it comprises: a central core (1), or flexible support, a coating (2,3) of the central core formed by a layer of resin made of a material   organic matter loaded with a mineral powder into determined portions.   12. Flexible insulating material according to the   cation 11, characterized in that the central core (1) is   constituted by a plastic material such as a poly-   ester (polyethylene terephthalate glycol).   13. Flexible insulating material according to one of   claim 11 or 12, characterized in that   organic material consists of a polymeric material   riseable based on acrylic material, polyurethane, epoxies or silicone.   14. Flexible insulating material according to one of   Claims 11 to 13, characterized in that the powder   mineral is a mica powder of less than 40 Nm.   15. Flexible insulating material according to one of   claims 11 to 14, characterized in that said   coating formed by a resin layer further comprises a bonding or coupling agent between the   organic material and the mineral powder.