CH648146A5 - Impregnable mica-based lapping tape for the insulation of high-voltage machines - Google Patents

Abstract

In a lapping (winding) tape for the insulation of high-voltage machines which comprises porous support material, mica and a binder and which can be impregnated with liquid epoxy resin curing system and in which the binder acts as a curing accelerator for the impregnation resin, the binder for the lapping tape comprises a) a product of the reaction of polyepoxide compounds with secondary alkylolamines in combination with b) at least one cycloaliphatic epoxy resin.

Description

** WARNING ** beginning of DESC field could overlap end of CLMS **.

PATENT CLAIMS 1. On the basis of porous carrier material, mica and a binder, built-up impregnable with liquid epoxy resin hardener system for the insulation of high-voltage machines, in which the binder acts as a curing accelerator for the impregnating resin, characterized in that the binder a) is a reaction product Polyepoxide compounds with secondary alkylolamines in combination with b) at least one cycloaliphatic epoxy resin.

2. Wrapping tape according to claim 1, characterized in that the mica is a mica paper and the binder is a resin mixture which is solid at room temperature and consists of a reaction product of polyepoxide and secondary alkylolamines in combination with at least one cycloaliphatic epoxy resin.

3. winding tape according to claim 1, characterized in that the mica split mica and the binder is a low to medium viscosity resin mixture of a reaction product of polyepoxide and secondary alkylolamines in combination with at least one cycloaliphatic epoxy resin.

4. winding tape according to claims 1 to 3, characterized in that the binder is a reaction product of a polyepoxide based on bisphenol and diethanolamine in combination with at least one cycloaliphatic epoxy resin.

5. winding tape according to claims 1 to 4, characterized in that the cycloaliphatic epoxy resins are ring epoxidized epoxy resins.

6. Wrapping tape according to claims 2, 4 and 5, characterized in that the mica paper is pre-impregnated with hardener-free cycloaliphatic epoxy resins, so that it has a solvent-free resin content of 0.5 to 3% by weight.

7. winding tape according to claims 3, 4 and 5, characterized in that the reaction product of the polyepoxide and diethanolamine as a component of the binder in the carrier material and / or in an additional covering material for the mica and as a second component of the binder is the cycloaliphatic epoxy resin Adhesive resin for connecting the mica particles to one another and to the carrier body or the cover is present.

8. Wrapping tape according to claims 1 to 7, characterized in that the porous carrier and cover material is paper, glass silk fabric, glass fleece or polyester fleece.

The invention relates to a winding tape constructed on the basis of porous carrier material mica and a binder and impregnable with a liquid epoxy resin hardening system for the insulation of high-voltage machines, in which the binder acts as a curing accelerator for the impregnating resin. In practice, such tapes are impregnated with a low-viscosity epoxy resin and a liquid anhydride hardener.

With the aforementioned impregnable mica-based winding tapes, bars or full-form coils etc. are continuously banded. Wrapping tapes with mica paper and split mica are common for this. The split mica tapes are usually used in combination with mica paper tapes.

For operating voltages up to about 10 kV and for machines of lower and medium power, the bars or full-form coils etc. are usually inserted into the slots after the impregnable winding tapes have been applied, and together with the stator core package of vacuum pressure impregnation (full impregnation) with a relatively low-viscosity impregnation resin subjected. After impregnation, the insulation is cured by appropriate heat treatments.

The following procedures are common for bars for machines with higher operating voltages and powers: A) The banded bars are placed in appropriate containers and impregnated with epoxy resin under vacuum and pressure. The bars or insulation are then hardened in appropriate molds.

B) The banded bars are in corresponding Molds made of steel or laminate and impregnated therein under vacuum and pressure. The molds are then cured. The shapes can be designed so that they either include the entire bars (including winding heads) or only the straight groove parts.

The viscosity of the impregnation resins must be so low that it is less than 300 mPa-s at the impregnation temperature for smaller machines and less than 100 mPa s for bars for high operating voltages. To on under To get 100 mPa-s, an impregnation temperature of around 70 C is usually used.

In order to increase the shelf life of the impregnating resins, it is common today to add the catalyst (accelerator) required for an economical curing time of the impregnating resins to the impregnable belt. For such purposes, e.g. Metal naphthenates and octoates, e.g. Cobalt or zinc naphthenate or octoate.

These naphthenates or octoates are placed in the form of a solution in the tape rolls before processing and the solvents are expelled again using hot air treatment. This process is used to treat mica paper and split mica-based tapes. A very disadvantage of these tapes is the relatively high solubility of the above.

Metal compounds in the resin at the usual impregnation temperatures.

In addition, it is difficult and, above all, very complex to get these metal connections evenly distributed in the tape rolls. Furthermore, the tan 6 values at 155 C in the case of the impregnated winding tapes hardened with this material are considerably above 100%, so that such insulations can only be used for thermal class B.

It has long been known to use reaction products made of polyepoxide compounds with secondary amines for mica paper tapes as adhesive resins. These resins have a catalytic effect on impregnation resins. A post-treatment of the strips with metal connections is therefore unnecessary.

(DE-OS 16 13 273, 16 14058 and DE-AS 22 15 206). In the two published documents examples are given in which there is a secondary amino group on each epoxy group. In DE-AS 22 15206 epoxy resins reacted quantitatively with secondary amine are mentioned.

It is stated that they are not washed out by the impregnating resin at 5060 C. At 70 C there is already a loosening. Such tapes have so far been used practically only for experiments. Large-scale operations have not yet taken place. The reasons for this will be dealt with in detail below.

Experience has shown that 8-10 g of adhesive resin per m2 are required to ensure good adhesion and thus perfect workability in the case of tapes based on mica paper with fiberglass fabrics or fleece as a backing. If you lay the most commonly used tape structure of approx. 120 g / m2 mica paper approx. 26 g / m2 glass silk fabric approx. 9 g / m2 adhesive (solvent-free, soluble in the impregnating resin)

and also based on a normal total binder content in the impregnated and cured under pressure or in a form of insulation of approx. 40%, this results in approx. 9.2% dissolved adhesive in the total binder or approx.

10.2 parts of adhesive per 100 parts of impregnating resin.

If reaction products of polyepoxide compounds with secondary amine are used as adhesives for this purpose, the same concentrations as above are obtained at an impregnation temperature of 70 ° C. For the most part, tapes (same glass silk and same adhesive content) with 150 g / m2 mica paper are also used. Then the adhesive concentrations in the binder are approx.7.7% or approx.

8.3 parts per 100 parts impregnating resin. In order to guarantee perfect impregnability at 70 C, one has to work with considerably lower concentrations of catalyzed resin. These are with the above Implementation products in the order of 3-6%. The optimum levels of accelerating adhesive resin are also in this range. At higher concentrations, the gelation times of an adhesive / impregnating resin mixture at 70 C are too short. That means the tapes cannot be impregnated properly. In addition, the properties of the entire insulation then become less favorable. In order to reach the optimal concentrations of 3-6%, attempts have been made to partially remove the adhesive, e.g. in the form of dots, rhombuses or other geometrical figures, which means that the carrier (fabric or fleece) is only glued to the mica paper at these points. The result is a relatively poor bond. This causes great difficulties in processing. In the case of the glass silk fabric, which is mostly used as a carrier, glass fibers emerge when the strips are cut, which also make processing very difficult. With the currently known reaction products of polyepoxide compounds with a secondary amine, it is not possible for the above reasons to satisfactorily glue mica paper and carrier together.

Furthermore, it has been shown that the previously known reaction products made of polyepoxide compounds with a secondary amine have a relatively high solubility in relatively high melting points in an approximately 70 ° C. impregnating resin.

Since the impregnation resin usually penetrates from the outside inwards into a corresponding tape winding, depletion of accelerating adhesive resin occurs in the outer tape winding. The consequence of this is that the insulation is relatively sticky on the outside after the normal curing time and is therefore practically unusable.

Impregnable mica paper tapes with glues containing catalyst must include To guarantee perfect processability and impregnation etc. and to achieve perfect insulation, the following are required: a) Mica paper and backing must be glued together so well that under normal conditions, the mica paper cannot be removed during processing.

b) If glass fiber is used as the backing, all parts of the fabric must be firmly attached to the mica paper, otherwise glass fibers will become detached during cutting and processing, which will greatly impair processability.

c) During the evacuation of the coils before vacuum impregnation (approx. 15 h at 70 C), the adhesive may only change slightly. At 80-130 C, it must later be perfectly soluble in the impregnation resin.

d) During the impregnation process at 70 C, the adhesive must hardly react with the impregnating resin for a period of approx. 68 h. The mixture may only increase its viscosity slightly; the mixture must not gel.

e) The adhesive that acts as an accelerator must practically not be so soluble at 70 C that impregnation of accelerator adhesive resin occurs in the outer tape layers during impregnation and thus the insulation becomes tacky on the surface after curing.

f) At 130 C, the impregnated insulation must be hardenable within 6 hours.

In the case of tapes with the previously known reaction products made from polyepoxide compounds with a secondary amine as the adhesive, it is impossible to meet all the justified and necessary requirements relating to a) to f). If 8-10 g / m2 is used as the adhesive, d) is not met. The gel times are 3-4 hours and less. If a concentration of 34% of the reaction products in the total binder is achieved by partial gluing (dots, rhombuses or other geometric figures), then the requirements will be happy. d), but not according to a) and b). The demands gladly. e) is never fulfilled.

The object of the present invention is to provide an impregnable winding tape based on mica and a catalyzed polyepoxy resin, which in particular likes all requirements. aff) and is also able to guarantee that the insulation after impregnation and curing with 130 C at 155 "C has a tan 6 at 0.2 UN of less than 100 vóo ((<0.1), for class F ( 155 C) can be used, can be processed dust-free and can be stored for at least 1 year under normal storage conditions.

This object is achieved according to the invention by the features mentioned in the characterizing part of claim 1. Further developments of the invention can be found in the subclaims.

The following process steps are used to manufacture the winding tape: 1) a resin which acts as a curing accelerator is a reaction product which is solid at room temperature and consists of a polyepoxide compound with secondary alkylolamines, 2) the reaction product is diluted with a cycloaliphatic ep resin or with a mixture of such resins in order to set the correct reactivity. Cycloaliphatic ep resins can be used advantageously for this purpose.

By appropriately mixing the reaction product with the dilution resin or with a mixture of resins, it is easy to set the reactivity required for practice for tapes with different square meter weights but with the same amount of adhesive (8-10 gim2), 3) the porous carrier (e.g. glass fabric or fleece) thus glues to the binder mixture so that there are no unwetted areas in the carrier, 4) the mica paper is pre-impregnated with hardener-free cycloaliphatic e-resin or with a mixture of such resins so that the content of solvent-free cycloaliphatic ep resin is between 0.5 and 3%. As a result, the later winding tapes can be processed dust-free.

Example I When choosing a suitable catalyzed (acting as an accelerator) ep resin, an almost quantitative reaction product of an epoxy resin based on bisphenol-A with an epoxy equivalent of about 550 with diethanolamine has proven to be particularly suitable. This product has the following characteristics: Softening point (ring and ball): 85 C epoxy number: 0.5-0.7% nitrogen content: approx. 2.2% Cycloaliphatic ring epoxidized Ep resins have proven to be particularly suitable as dilution resins.

Bisphenol-Ep, hydantoin and cycloaliphatic diglycidyl ester resins are less suitable.

As an adhesive resin for a tape with 150 g / m2 mica paper and 26 g / m2 glass silk is a mixture of 10 parts of the reaction product of polyepoxide and diethanolamine acc.

Example I and 2-3.5 parts of a ring epoxidized cycloaliphatic carboxylate type polyepoxide are advantageously used.

In the case of a tape with 120 g / m2 of mica paper and 26 gim2 glass silk, the proportion of the reaction product according to Example I must be reduced accordingly. A mixture of cycloaliphatic polyepoxides, which can also be used to pre-impregnate the mica paper, is suitable for dilution. A suitable mixture of a liquid cycloaliphatic ep resin which is liquid at room temperature and a solid ep resin is advantageously used to set the desired flexibility. The mixtures according to the invention with the reaction resin can be used as solutions in acetone or methyl ethyl ketone with additions of methyl glycol and / or isopropanol.

A content according to Example I of 5-5.5% is optimal for the total binder.

Since the binder is practically insoluble at 70 C, the mica paper tapes can be used universally, i.e. can be used for impregnation processes A and B as well as for complete impregnation.

Particularly good impregnability is achieved with tapes with openly woven glass silk, in which mica paper and glass silk are bonded to one another in such a way that the fabric fields between the weft and warp threads are free of adhesive and at least 50% of the surface of the mica paper facing the fabric backing is not wetted by the adhesive and remains permeable to the impregnation resin; however, paper, glass fleece or polyester fleece or other organic or inorganic carrier material or cover material can also be used as the porous carrier material.

Compared to a known reaction product from a polyepoxide compound with diethylamine, the reaction product according to the invention contains practically twice as many free OH groups.

This will significantly intensify the subsequent crosslinking, which will result in a reduction of the dielectric losses in the heat (e.g. at 155 "C).

The shelf life of the tapes produced according to the invention is excellent. The structure of the tapes (e.g. flexibility) practically does not change.

The tapes with mica paper according to the invention meet all requirements according to. a) f). When using these tapes, after impregnation and curing for 6 hours at 130 C at 160 C, tan 6 values are around 90% (0.09). When properly impregnated, the tan b risers are practically zero. Long-term tests at 160 C with interim cooling to room temperature over several months have shown that there is no deterioration in tan 8 increases.

When the tapes according to the invention are impregnated at 70 ° C., the binder practically does not dissolve in the impregnating resin.

The binder dissolves very well at temperatures of 80 C and above. Insulations produced with this are completely tack-free on the surface after curing. The dilution resin component is installed perfectly in the impregnation resin.

When processing the tapes according to the invention, there is no nuisance caused by mica dust. The backing and mica paper are perfectly bonded.

As large-scale tests have shown, such a tape can withstand all practical requirements according to the invention.

In a further embodiment of the invention, it has proven to be advantageous to also produce wrap tapes based on split mica with the binder resin of the invention.

In practice, reaction products made from polyepoxide compounds with a secondary amine have not previously been used for impregnable split mica tapes.

The main difficulty lies in the fact that relatively low viscosity resins have to be used as binders for these tapes at room temperature and the previously known reaction products of polyepoxides with secondary amines are all solid to highly viscous at room temperature. Therefore, liquid, hardener-free Ep resins are mostly used and the rollers are subsequently impregnated with metal compounds as an accelerator additive.

Example II Because of the good experience with impregnable mica paper tapes with a reaction product of a polyepoxide compound with diethynolamine according to the invention, an attempt has initially been made to obtain reaction products that are liquid at room temperature on this basis.

This was accomplished without great difficulty. A bisphenol-A epoxy resin with an epoxy equivalent of 185 and a viscosity at room temperature of about 11000 mPa x s has behaved most favorably as the starting resin for the purpose in question.

A reaction with diethanolamine gives a product with the following values: Viscosity of a 69% resin solution at 25 C: 1840 mPa s epoxy number in the solvent-free resin: 0.10-0.40% nitrogen content in the solvent-free resin: approx. 4.8%.

With approx. 230 g / m2 split mica and a support applied on both sides, such a tape works with approx. 1520 g / m2 liquid binder. If only the reaction product according to Example II is used for this, then with a later total binder content in the insulation of approximately 23 to 25%, the proportion of dissolved binder in the impregnating resin is much higher than in the mica paper tape. It must be taken into account here that, due to the higher nitrogen content, the reactivity of the reaction product which is liquid at room temperature is significantly higher.

The sole use of liquid reaction product is therefore unsuitable.

Here, too, the dilution principle with cycloaliphatic ep resins, which has been tried and tested in fine mica tapes, has been used with great success according to the invention. The following mixtures have proven their worth as binders Impregnation process Reaction A B product according to the invention which is liquid at room temperature (Example II) = 10 parts = 10 parts.

liquid, ring epoxidized cycloaliphatic polyepoxide = 33-40 parts = 5050 parts A) = single impregnation B) = form impregnation.

Optimal for the total binder is a content of the reaction product (liquid at room temperature) according to the above of 3-3.5%.

If one builds up insulation from the split mica tape according to the invention in connection with the fine mica tape according to the invention so that at least one or two outer layers consist of mica paper tape, all of the requirements a) -f) listed for the mica paper tapes are completely met.

With such insulations, tan 6 values at 0.2 UN and 130 C of approx.

60% o. The tan 6 increases are practically zero.

Insulations of this type have proven their worth in large and long-term tests.

In the form of impregnation (B), the split mica tape insulation only absorbs the amount of impregnating resin required to fill the cavities during vacuum impregnation.

That is about 17-20%. Together with the binder, which is already in the belt, the total binder content will then be approx. 23-25%.

In the case of single impregnation (A), the amount of impregnating resin absorbed during vacuum impregnation is higher, based on the tape, it is between 35 and 55% depending on the insulation thickness.

When the insulation is subsequently pressed and hardened in the coil press, the excess resin is then pressed out until the final binder content is approx. 23-25%. The binder according to the invention, consisting of the reaction product which is liquid at room temperature and the cycloaliphatic dilution resin, mixes with the impregnation resin during the impregnation. During later pressing, a corresponding proportion of liquid reaction product is then pressed out together with the excess resin. For this reason, the proportion of the reaction product that is liquid at room temperature in the binder of the tapes for individual impregnation (A) must be higher than for form impregnation (B).

In a further development of the invention, it was provided to develop an impregnable split mica tape with catalyzed Ep resin, which can be used universally for processes A and B. This is achieved in that the reaction product of bisphenol A epoxy resin with diethanolamine (example I), which has been tried and tested for impregnable mica paper tapes and is solid at room temperature, is added in the required amount to the porous carrier materials and / or to the covering material for the mica and a cycloaliphatic ep resin which is liquid at room temperature is used as a binder for the split mica and as an adhesive for split mica with a carrier material.

The reaction product according to the invention, which is solid at room temperature, does not dissolve at 70 ° C. either in the impregnating resin or in the cycloaliphatic polyepoxide. When pressing the impregnated wraps under vacuum, the reaction product is therefore practically not pressed out. The tape can therefore be used universally.

When using, for example, approx. 230 g / m2 split mica and a cover on both sides with 20 g / m2 polyester fleece in each case, 2.1-2.3 g reaction product (Example I) per m2 fleece are obtained in each fleece layer. A thin solution of the reaction product in acetone or methyl ethyl ketone with additions of methyl glycol and / or isopropanol can be used to impregnate the fleece.

The nonwoven material impregnated with the reaction product according to the invention is practically as flexible after the expulsion of the solvents as the unimpregnated nonwoven.

At temperatures above 80 C to 130 C, the reaction product in the porous carrier materials dissolves in the impregnating resin and there is a perfect mixing with the binder in the cracked mica and with the impregnating resin. Tan 8 at 130 C and the Tan 8 increases are similar to the use of reaction product which is liquid at room temperature (Example II).

These split mica tapes according to the invention, alone or in combination with mica paper tapes, meet the requirements a) -f) listed for tapes based on mica paper.

Overall, the impregnable split mica tapes with reaction product that is liquid at room temperature and that is solid at room temperature are practically equivalent. The production process for tapes with a reaction product that is solid at room temperature is somewhat more complex because of the separate impregnation of the carrier materials required here.

Both types of tape can be stored for at least 1 year at normal storage temperature.

In the preparation of the reaction products, polyepoxide compounds are dissolved, e.g. implemented in methyl ethyl ketone with the appropriate amount of diethanolamine in a reflux condenser.

In addition to the bisphenol-Ep resin-based system and liquid anhydride hardener mentioned above, other impregnating resins which can be cured with acid anhydrides, such as those based on cycloaliphatic and mixtures of Ep resins with unsaturated polyester resins, can be used as impregnation resins.

In practice, reaction products made from polyepoxides with diethanolamine have proven particularly suitable; However, reaction products of polyepoxides with other secondary alkylolamines can also be used for the invention, depending on the requirements to be made.

Claims (8)

PATENT CLAIMS 1. On the basis of porous carrier material, mica and a binder, built-up impregnable with liquid epoxy resin hardener system for the insulation of high-voltage machines, in which the binder acts as a curing accelerator for the impregnating resin, characterized in that the binder a) is a reaction product Polyepoxide compounds with secondary alkylolamines in combination with b) at least one cycloaliphatic epoxy resin. 2. Wrapping tape according to claim 1, characterized in that the mica is a mica paper and the binder is a resin mixture which is solid at room temperature and consists of a reaction product of polyepoxide and secondary alkylolamines in combination with at least one cycloaliphatic epoxy resin. 3. winding tape according to claim 1, characterized in that the mica split mica and the binder is a low to medium viscosity resin mixture of a reaction product of polyepoxide and secondary alkylolamines in combination with at least one cycloaliphatic epoxy resin. 4. winding tape according to claims 1 to 3, characterized in that the binder is a reaction product of a polyepoxide based on bisphenol and diethanolamine in combination with at least one cycloaliphatic epoxy resin. 5. winding tape according to claims 1 to 4, characterized in that the cycloaliphatic epoxy resins are ring epoxidized epoxy resins. 6. Wrapping tape according to claims 2, 4 and 5, characterized in that the mica paper is pre-impregnated with hardener-free cycloaliphatic epoxy resins, so that it has a solvent-free resin content of 0.5 to 3% by weight. 7. winding tape according to claims 3, 4 and 5, characterized in that the reaction product of the polyepoxide and diethanolamine as a component of the binder in the carrier material and / or in an additional covering material for the mica and as a second component of the binder is the cycloaliphatic epoxy resin Adhesive resin for connecting the mica particles to one another and to the carrier body or the cover is present. 8. Wrapping tape according to claims 1 to 7, characterized in that the porous carrier and cover material is paper, glass silk fabric, glass fleece or polyester fleece. The invention relates to a winding tape constructed on the basis of porous carrier material mica and a binder and impregnable with a liquid epoxy resin hardening system for the insulation of high-voltage machines, in which the binder acts as a hardening accelerator for the impregnating resin. In practice, such tapes are impregnated with a low-viscosity epoxy resin and a liquid anhydride hardener. Lattice bars or full-form coils etc. are continuously banded with the aforementioned impregnable mica-based winding tapes. Wrapping tapes with mica paper and split mica are common for this. The split mica tapes are usually used in combination with mica paper tapes. For operating voltages up to about 10 kV and for machines of lower and medium power, the bars or full-form coils etc. are usually inserted into the slots after the impregnable winding tapes have been applied, and together with the stator core package of vacuum pressure impregnation (full impregnation) with a relatively low-viscosity impregnation resin subjected. After impregnation, the insulation is cured by appropriate heat treatments. The following procedures are common for bars for machines with higher operating voltages and powers: A) The banded bars are placed in appropriate containers and impregnated with epoxy resin under vacuum and pressure. The bars or insulation are then hardened in appropriate molds. B) The banded bars are in corresponding Molds made of steel or laminate and impregnated therein under vacuum and pressure. The molds are then cured. The shapes can be designed so that they either include the entire bars (including winding heads) or only the straight groove parts. The viscosity of the impregnation resins must be so low that it is less than 300 mPa-s at the impregnation temperature for smaller machines and less than 100 mPa s for bars for high operating voltages. To on under To get 100 mPa-s, an impregnation temperature of around 70 C is usually used. In order to increase the shelf life of the impregnating resins, it is common today to add the catalyst (accelerator) required for an economical curing time of the impregnating resins to the impregnable belt. For such purposes, e.g. Metal naphthenates and octoates, e.g. Cobalt or zinc naphthenate or octoate. These naphthenates or octoates are placed in the form of a solution in the tape rolls before processing and the solvents are expelled again using hot air treatment. This process is used to treat mica paper and split mica-based tapes. A very disadvantage of these tapes is the relatively high solubility of the above. Metal compounds in the resin at the usual impregnation temperatures. In addition, it is difficult and, above all, very complex to get these metal connections evenly distributed in the tape rolls. Furthermore, the tan 6 values at 155 C in the case of the impregnated winding tapes hardened with this material are considerably above 100%, so that such insulations can only be used for thermal class B. It has long been known to use reaction products made of polyepoxide compounds with secondary amines for mica paper tapes as adhesive resins. These resins have a catalytic effect on impregnation resins. A post-treatment of the strips with metal connections is therefore unnecessary. (DE-OS 16 13 273, 16 14058 and DE-AS 22 15 206). In the two published documents examples are given in which there is a secondary amino group on each epoxy group. In DE-AS 22 15206 epoxy resins reacted quantitatively with secondary amine are mentioned. It is stated that they are not washed out by the impregnating resin at 5060 C. At 70 C there is already a loosening. Such tapes have so far been used practically only for experiments. Large-scale operations have not yet taken place. The reasons for this will be dealt with in detail below. Experience has shown that 8-10 g of adhesive resin per m2 are required to ensure good adhesion and thus perfect workability in the case of tapes based on mica paper with fiberglass fabrics or fleece as the backing. If you lay the most commonly used tape structure of approx. 120 g / m2 mica paper approx. 26 g / m2 glass fiber fabric approx. 9 g / m2 adhesive (solvent-free, soluble in the impregnating resin) ** WARNING ** End of CLMS field could overlap beginning of DESC **.