DE2237354C3 - Insulating materials suitable for high voltage purposes - Google Patents

Description

rich radiation, ζ. B. β or γ rays are crosslinked, the radiation can cause radiolysis of the hydrate, so that water is formed. This water remains absorbed in the polymer-filler mixture until it is then heated, for example for expansion or deformation purposes, or during operation, with foam formation taking place. Such a foam (if a large amount of filler undergoes radiolysis) or even the formation of a few bubbles has the same catastrophic effect as the porosity described in Section 1 above.

3. In the case of heat-shrinkable molded parts, the heat is necessary to carry out the shrinking process is required at an economical rate, so high that water of hydration is lost. If the shrink temperature is very high, this water loss can cause porosity, and itself if no porosity is formed, the loss of any water so degrades the quality and effectiveness of polymeric insulation in contaminated environments.

From DT-OS 2 050 581 there is already an electrical insulating material which is further improved in terms of creepage path formation known that from one or more polymers and an additive fine-grain aluminum oxide hydrate and other fillers. The hallmark of this improved electrical insulation material consists in a content of aluminum oxide hydrate of a certain specific surface area of at least 2 m * / g and an addition of oxides of transition metals, lanthanide metals or Actinide metals.

The object of the present invention is to create an electrical insulating material that is as small as possible Shows tracking and is cheaper to manufacture compared to the known electrical insulation material is, more water-resistant and its additives to the tracking inhibiting fillers that Do not discolour electrical insulation material.

This object is achieved by the features of claim 1. The invention relates to insulating materials for high voltage purposes made of a polymeric material and a tracking preventing Filler system

a) at least 20 percent by weight of aluminum oxide trihydrate and

b) at least 1 percent by weight of another filler material,

which are characterized in that the second filler consists of chemically treated silicon dioxide, which is composed of an inorganic Si-O-Si group-containing compound by treatment with one or more organic silicon compounds.

Under a "chemically treated silicon dioxide filler" a filler is to be understood, which consists of an inorganic silicon-containing compound, which contains the Si-O-Si group and treated with one or more organic silicon compounds has been. However, the following is a brief description of these chemically treated silicas and their production.

The inorganic silicon-containing filler generally consists of sulphate or a metal silicate, e.g. B. aluminum silicate, magnesium silicate, calcium sulfate or calcium aluminum filtrate. It is normally regarded as a reinforcing filler and has a specific surface area of at least 40 m ^: / g, preferably at least 50 m ^s / g, measured according to the nitrogen adsorption method of Brunauer, E mme 11 and Teller (BET method). Particularly advantageous fillers for the purposes of the invention have specific surface areas in the range from 200 to 250 m ^s / g. The filler can be anhydrous, ie contain less than 3.5% bound water. It can be hydrated or an airgel (made, for example, by the method described by Bachman and coworkers in Rubber Reviews 1959, publication by Rubber and Chemistry and Technology).

The inorganic silicon-containing fillers are used to produce the chemically treated fillers with one or more silanes and / or with other organosilicon compounds, e.g. B. Octamethyltetracyclosiloxane and tetramethylcyclosuoxane. Treatment can be based on a number of proceedings. For example, the filler with a gaseous silane, e.g. B. Dimethyldichlorosilane, treated at elevated temperatures, or one can use the filler and the silane mix mechanically and store mixture until wrapping is complete. The time it takes for completion the coating is necessary, depending on the temperature in the range of 1 day up to several weeks. However, the method of treating the filler with the silane is within limits of the invention insignificant. The filler advantageously becomes at least one level with the silane enveloped monomolecular layer, however, fillers, the surface of which is only a smaller one Part coated with silane can be used for the purposes of the invention.

Substituted silanes of the formula are particularly preferred as silanes

R »SiX <-»

in the η for 1, 2 or 3, R for an organic radical, which is bonded to "the silicon atom via a Si-C bond, and X stands for a radical which is via a Atom (excluding a carbon atom) is bonded to the silicon atom. More suitable as examples Compounds are gena; .nt: methyltrichlorosilane, dimethyldichlorosilane, Trimethylchlorosilane, vinyltrichlorosilane, y-methacryloxypropyltrimethoxysilane and its Hydrolysis product fc.y-methacryloxypropyl-triethoxysilane and its hydrolysis products, N, N-bis - (/? - hydroxyethyl) -y-aminopropyltriethoxysilane and its hydrolysis products, Vinyltriälhoxysil; in and its Hydrolysis products, y-glycidoxypropyltrimethoxysilane, y-mercaptopropyltrimethoxysilane and its Hydrolysis products, /? - (3,4-epoxycyclohexyl) ethyltrimethoxysilane and vinyl trimethoxysilane. Particularly preferred for the production of cnemically treated Fillers which are suitable for the purposes of the invention are Dimeihyldichlorsüan, Triinelhylchlorosilan, y-glycidoxypropyltrimethoxysilane, Vinyltriäthoxysilan.y-Methacryloxy-propyltrimethoxysilan, γ-Melhacryloxy-propyltriäthoxysilan and /? - (3,4-Epoxycyclohexyl) -äth> itrimethoxysilan.

. The presence of functional organic oxides, especially the cycloaliphatic epoxides, Remnants R In den Sijanen allows the setting of the to be named.

Compatibility and / or reactivity of the particularly suitable polymers are, for example

Synthetically treated silicon-day-fillers with the polyethylene, Alhylcn-Metbylacrylal- and A'hylen-

various polymers. 5 Ethyl acrylate copolymers, ethylene-methylene-eth-

It has surprisingly been found that the acrylic polymers, ethylenvinylacetate copolymers treated silicon dioxides, the porosity merizate, ethylene-propylene copolymers, copolymers considerably reduce during processing or merizates of ethylene with propylene and nonconjugate. Since they are hydrophobic, dienes (e.g. 1,4-hexadiene, dicyclopentadiene are to be reckoned with, as "they absorb water from the inorganic hydrate and ethylidene norbornene), chlorosulfonated polyamide. A commitment to ethylene, polypropylene, Polydimethylsiloxane, Dimethyl A theory is not intended, however, an-siloxane-methylvinylsiloxane copolymers, fluorosilicate, are assumed to be able to reinforce the polymeric cone, e.g. mass produced from 3,3,3-trifluoropropylsiloxane, and to increase the internal modulus of elasticity - fluorosilicones, carborane siloxanes, e.g. the commercial gemund prevent the dilution in this way, 15 products "Dexsil" (manufacturer by Mathieson), poly-oil which is essential for pore formation. Butyl acrylate, butyl acrylate-ethylacrylal copolymer is also possible, that they act as lubricants and thereby reduce heat build-up during processing, butyl acrylate-glycidyl-methacrylate copolymers, polybutylene, butyl Rubber, ionomeric poly or uniform dispersion of the inorganic merizate and mixtures of two or more of the hydrais. Even more surprising is the solid 20 aforementioned polymers,
position that they increase the resistance of the system to particularly advantageous insulating materials in accordance with the formation of creepage paths. Invention are networked and preferably have the

The alumina trihydrate preferably has a heat recovery property

specific surface, for example in the range of 1 effect. For example, the insulation can be the

up to 20 m ² / g, in particular 2 to 16 mVg - the maximum form of heat-shrinkable pipes, hoses,

Particle size is preferably 4 μ, advantageously insulating bells etc. for use in cable

2 μ, joints or the shape of heat-shrink -

The alumina trihydrate is usually available in cash end caps for cable terminations. the

an amount in the range from 25 to 70% by weight, the invention therefore also includes molded parts that

the polymeric material and the tracking 30 insulating material according to the invention and

preventive filler system present, but possibly resilient due to the action of heat

higher proportions can also be used.

especially if it is not intended, the insulating die can be processed into the insulating material

material the property of resilience by suitable masses according to the invention can press-

To give warmth. The preferred proportion of 35 bar, injection moldable or extrudable and made

Hydrates will of course vary depending on the a mixture of one or more polymer

polymeric material to which it is to be added and one which prevents tracking

(certain polymers have a stronger tendency to exist in a filler system which, based on the

for tracking than others), and also with the weight of the polymer or polymers and the

Environment in which the insulation will be used 40 tracking preventing filler system

target. However, it can easily be determined experimentally from at least 20 percent by weight of aluminum oxide

and is generally in the range of 40 to 70%, trihydrate and at least 1 percent by weight of a chemical

in particular 40 to 65%, based on the weight of the mixed treated silicon dioxide filler of the

the polymeric material and the type of scent path formation described above,

preventive filler system. 45 The insulation materials and compounds according to the

The preferred amount of the treated silicon compound can optionally also contain other fillers,

dioxyds is generally in the range from 2 to e.g. B. flame retardants, reinforcement fillers

20% of the weight of the polymer material and of the substances, pigments and mixtures of these fillers

the filler system preventing tracking. keep. The filler which prevents creepage

Amounts in the range of 3 50 substance system and any other fillers, etc., are particularly preferred

up to 10 percent by weight. the polymers according to any customary

Polymeric processes, e.g. B. on two-roll mixers, in Banburysate used, which are mixed in after pyrolysis in a carbon mixer or extrusion press, have a deficit of less than 10%. If this is also the case, the masses obtained can be polymerized a very high char residue 55 common methods easy to plate, coarse, it is not possible to also film the creepage path formation. Process foils and other molded parts, to be used with very high proportions of the filler system. The insulating materials according to the invention are prevent. The carbonization residue can easily be used particularly advantageously as high-voltage insulation, by a TGA measurement, for example under voltage, for example for voltages up to 11 kV or even more Use of a Perkin-Elnner thermobalance under 60 higher up to, for example, 33 kV, for example as a turn away of flowing «air at a heating end for paper cables. The invention includes speed of 40 ° C / minute. according to also electrical high-voltage equipment,

From the polymeric materials in which the the in which a component is made by these Isoliermaterialier

System preventing creep formation is appropriately isolated.

The invention is illustrated by the following examples

Olefin polymers, which are further explained from two or more mono-. In these examples, sicr

mcrcn are made, especially the terpoly- all parts and percentages by weight, if

merisate, polyacrylate, Siliconpolymcrisatc and Ep- not stated otherwise.

Examples 1 to S.

Mixtures of the following composition were prepared in a laboratory two-roll mixer at 120 ⁰ C:

1 mixture 2 3 No.. 5 4th Ethylene propylene Dicyclopecntadicn- 50 50 50 50 Terpolymer ... 50 Ethylene-ethyl- acrylate copoly 50 50 50 50 merisat 50 Polyethylene 40 40 40 40 low density .. 40 Polymerized Dihydroquinoline 8th 8th 8th 8th as an antioxidant .. 8th Aluminum oxide hydrate (BET surface area 150 150 150 150 1.7 m * / g) 150 Treated silicon dioxide as a filler 10 . fabric A Untreated - 10 - - Silica B - Untreated Silicon dioxide B, - - 10 - treated with 1 χ - Untreated Silicon dioxide B, - - - - treated with 2xx 10 Untreated Silicon dioxide B, treated with 10 3 xxx 2 2 2 2 Triallyl cyanurate .... 2 2,5-dimethyl-2,5-di- tert-butylperoxy- 4th 4th 4th 4th hexyne-3 4th

The product A (manufacturer Degussa) is a with trimethylchlorosilane Encased silicon dioxide filler with a BET surface area of about 150 m * / g-

Product B (manufacturer Degussa) is untreated Silicon dioxide filler. with a surface of about 200 mVg.

The silane (manufacturer Union Carbide) consists of the following compounds:
AIx = / HS ^ epoxycyclohexyO-ethyltrimethoxy-

silane,
A 2 xx = y-glycidoxypropycrimethoxysilane,

A 3 xxx = vinyl trilthoxysilane.

The silica was coated with the above-mentioned silanes by adding a mixture consisting of the Silicon dioxide and 5 percent by weight of the silane (based on the silicon dioxide) consisted in a polyethylene bag was shaken at room temperature for a week.

Plates of 12.7 x 5.08 χ 0.64 cm were 15 minutes pressed at 200'C for physical and electrical tests.

Mixture 2 blistered when pressed, while the other mixes gave no porosity. The following physical properties were determined for the other mixtures:

Tensile strength, kg / cm ¹ .

Elongation at break,%

Dielectric strength,
ν / 25.4µ

Mixture No. 1I3I4I

49 610

535

86 285

650

88 305

590

Mixtures 3 and 4 were tested according to ASTM D 2303. (What is measured here is the resistance

ability to prevent tracking and erosion in polymeric insulators using the inclined method Level using a liquid impurity,.) The impurity was 0.02% of a wetting agent, Condensation product from tert-octylphenol

* ° with 9 to 10 moles of ethylene oxide and 0.1% ammonium chloride containing mixture with a resistivity of 330 ohm-cm was used. The flow rate was 0.15 ml / minute and the initial voltage was 2.0 kV. After every hour the

* ⁵ Voltage increased by 0.25 kV.

After a Tesiper period of a total of 200 minutes, the test of mixture 3 was canceled because the sample was no longer self-supporting due to the existing large eroded crater. Not at all

Tracking had taken place. Mixture 4 was likewise again without after 200 minutes Tracking removed. Only one large erosion crater was present.

Examples 6 to S.

Mixtures of the following composition were prepared on a laboratory scale mixer. Test specimens in the form of platters were pressed for 15 minutes at 200 ⁰ C.

Silicone elastomer.

Low density polyethylene
MFI 3.0

Alumina trihydrate

(BET surface area 1.7 m ² / g).
Fe ₈ O ₈

Silica A

Silica B

Triallyl cyanurate

Mix no.

⁶ I ⁷ I ⁸

70 20

30 5

0.2 0.2

70 20

30 5

5 0.2

0.2

peroxyhexine-3

Mixtures 6 and 7 foamed immediately

Presses, and one for measuring the physical!

Properties suitable plate could not be produced will. The test panel pressed from Mixture 8 had the following properties:

Tensile strength 91 kg / cm »

Elongation at break 455%

Dielectric strength 11.8 kV / mm

Specific gravity 1.20

This example clearly illustrates that di Use of the treated fillers according to de

709 608/433

Invention of the formation of porosity in molded parts, which are made from these mixtures, prevented.

The test plate made from mixture 8 was tested in accordance with ASTM D 2303, the impurity used being a solution containing 0.02 % glycerol-ethylene oxide condcnsate (Conox Y 102, manufacturer Prices [Bromborough] Ltd.) as a non-ionic wetting agent and 0, 1% ammonium chloride and had a resistivity of 380 ohm-cm at 23 ° C. Line test voltage of 3 kV was applied. The solution was applied at a rate of 0.30 ml / minute. The time required to form a 25.4 mm Kricchwegc was 1418 minutes.

Mixtures similar to Mixtures 6 through 8 were made using 70 parts of a different silicone polymer (Manufacturer Dow Corning).

The results on porosity were the same as in the case of Examples 6 to 8. Only the mixture containing silica A showed no porosity after processing. The time until it took 1580 minutes for this sample to form a creepage distance of 25.4 mm.

Examples 9-14

Mixtures of the following composition were prepared on a laboratory roller mixer:

⁹ 10 Mix no. ^12th » 14th Ethylene pro pylene di- cyclopenta- diene terpoly 100 100 100 100 100 meres 100 Polyethylene lower 33 33 33 33 33 density 33 Ethylene-ethyl- acrylate co- 33 33 33 33 33 polymer .. 33 Chlorosulf o- ned poly 30th 30th 30th 30th 30th ethylene 30th Chemically pure 10 10 10 10 10 Silica A 10 Polymerized 1,2-dihydro 2 ^ .4-tri- methyl- 6th 6th 6th 6th 6th quinoline 6th Magnesium- 10 10 10 10 10 oxvd 10 Aluminum- oxide trihydrate (BET upper 150 175 225 250 275 nacne
l, 7mVg) _: · -. 10 10 200 10 10 10 10 • ^ 1 ^ 3
2,5-dimethyl 2.5-di-tert.- butylperoxy S. 5 5 5 5 hexyne-3 5

Test specimens in the form of sheets were pressed for 15 minutes at 200 ⁰ C. No pores were found in any of the samples. This clearly illustrates the influence of the treated silica used as filler, even when heavily filled with alumina trihydrate.

The following physical properties were determined for the samples:

»5

23 ° C

Tensile strenght,

kg / cm ¹

Elongation at break,
° /

Dielectric strength,

kV / mm ....
»5

150 ⁰ C

Tensile strenght,

kg / cm *

100% module,
kg / cm * ..

Elongation at break,

O/

200 ° C
35

Tensile strenght,

kg / cm *

100% module,

kg / cm ²

Elongation at break,
V

/O

⁹ 10 Mishu
^11th ng no.
¹² I. ¹³ I. 99 89 93.5 88 72.4 475 525 475 470 445 13.2 12.8 13.4 12.6 12.8 19th 15.5 20th 20.4 19th 15th 10.5 16.5 16.2 16.2 150 300 175 200 165 19.3 14.4 19.3 18.6 17.6 16.2 8.8 16.5 15.5 14.8 160 285 155 165 125

63 415

14.8 12 205

15.5 13 165

Some blends were tested according to ASTM D 2303 at a constant tension of Subjected to 6 kV, a solution used as an impurity containing 0.02% glycerol-ethylene oxide condensate as a wetting agent and 0.1% ammonium

chloride and had a resistivity of 380 ohm-cm at 23 ° C. This solution was abandoned at a rate of 0.30 mm / minute.

Mix no. Time to form a
Creepage distance of 25.4 mm
at 6 kV, minutes 10
11th
12th 1117
1254
1672

Examples 15-17

Mixtures of the following composition were prepared on a laboratory roller mixer:

\ l)

Silicone elastomer creams

Low density polyethylene ..
Ethylene-ethyl acrylate-copoly-

merisat

(18% ethyl acrylate)

Ethylene-propylene-1,4-hexadiene

Terpolymer

Silica A

Silica B

Silane 1

Aluminum oxide trihydrate
(BET surface area 1.7 m »/ g)

Fe ₁ O,

Polymerized 1,2-dihydro-2,2,4-trimethylquinoline

Triallyl isocyanurate
ZS-Dimethyl- ^ S
peroxyhexine-3

15th

30th

70 10

2 2

15th

30 10

70 10

15th

30th

10

70 10

2 2 In the mixture 17, the silica B treated with the silane by subjecting the mixture shaken in a Polyäthylenbcutcl one week and then for 4 hours heated to 100 ⁰ C.

The samples were made into panels for testing electrical properties in the manner described above pressed according to ASTM D 2303. The panel pressed from Mixture 15 contained bubbles and showed when cutting through and tearing thick layers

formation or lamination and a fibrous crack. The other samples 16 and 17 were fine and showed excellent results when tested Tracking.

Under the same conditions as in the case of the

In Examples 10 to 12, the time to creep path formation was over 5000 minutes for both mixtures.

B e i s ρ i e I e 18 to 20

Mixtures of the following composition were prepared in a Zweiwaizenmischer at about 110 ⁰ C:

Ethylene propylene dicyclopenta-

diene terpolymer

Ethylene-ethyl acrylate-copoly-

merisat

Low Density Polyethylene Polymerized Tetrahydro-

quinoline as an antioxidant

Iron (III) oxide

Chemically treated silica

as a filler

Alumina trihydrate

Triallyl cyanurate

Mix no.

100

40

8th 20th

20th

150

19 I. 20th 100 130 30th 40 40 8th 8th 20th 20th 20th 20th 150 200 2 2

The chemically treated, used as a filler Silica consisted of a Kicselaerogel that with dimethyldichlorosilane to the extent of approximately a monomolecular layer was enveloped. iThis Filler had a specific surface area of about 15OmVg (BET method) and a mean particle

raLTMiäwn were mm to hoses with an inner diameter of 25.4 and J ⁱⁿ "£ andstärke of 2.8 mm at temperatures to 1501 C (at the nozzle of Straigprer.se) with good porosity and without Oberilachcnbeschaffenheit extruded

For comparison, a mixture was produced was identical to mixture 18 but did not contain any filler. If this mixture underjkn extruded conditions mentioned above became tubing with a rough surface finish and some internal blisters..E »ar not possible the formation of bubbles "" hose by changing the extrusion compression ratio to ν. 1 ■> T ν

All mixtures were pressed into 12/x 5.08 χ 0.64 cm plaques. The panels were taking Nitrogen irradiated with y-rays up to a dose of 15 M rad. The plates were then made according to

50 ASTM D 2303 tested at a constant voltage of 6 kV. A solution was used as the impurity the 0.1% glycerine-ethylene oxide condensate .'Cenox Y102) and 0.1% ammonium chloride and a specific resistance of 380 ohm-cm

55 23 ° C. The solution was in an amount of Abandoned 0.9 ml / minute. The following results were obtained:

Time to education a creepage distance 6o mixture no. from 25.4 mm to 6 kV Minutes Comparison mixture . (porous)
⁶⁵ 18 42
770 19th > 1000 20th > 1000

These results illustrate the significant improvement of the resistance to tracking and the absence of porosity which can be achieved by the addition of chemically treated Siliciumdicxyds as a filler.

Claims (10)

1 ν ^: - ■ ² polymeric material cross-linked and preferably «* Ί-. . is resilient through heat. ^v J Patent claims: _r \> - »: ^% 1, insulating materials for high voltage purposes 5
*** made of a polymer material and a creep formation-preventing filler system. "," N _em μ r ; ' : a) At least 20 weight percent aluminum polymeric materials are used on a large scale Π Oxydtnhydrat and ^{för di {} * Isolation of the most diverse electrical b) at least Ϊ percent by weight of another »« equipment and components used, but suitable Filler. ^{Sic not for tlas Hocns} P ^annun g ^s S ^e o ⁱ et in vdadurcJi ge k * Ounce c h aet that Jer, purified atmospheres where moisture or mist second filler made of chemically treated SiIi- together with salts dust particles and ionic ciuradioxyd, which consists of an inorga- impurity the flow of Knechstromen or Nicheo Si-O-Si group containing compound 15 stray currents over the surface of the by treatment with one or more organ- isolation cause. This current causes you niche silicon compounds has been obtained. Temperature rise and consequently evaporation 2. Insulating materials according to claim 1, characterized by moisture and finally the formation of characterized as using the alumina tri-dry tapes. The electrical stress on hydrate in an amount of 25 to 70%, preferred ao these drying belts often exceeds the penetration from 40 to 70 percent by weight. Impact strength of the air-insulation interface, see above 3. Isöliermaterial according to claim 1 or 2, that discharges or spark spinning take place, characterized in that they chemically The radio temperature is extremely high and often chests treated filler based on silicon dioxide at 2000 ⁰ C or higher, and the heat generated can be in a Amounts from 2 to 20 <, preferably from 3 to 30, are sufficient to contain the surface of the insulation below up to 10 percent by weight. to damage the eventual formation of charred areas. 4. Isoliermaterialicn according to one of claims 1 These charred areas usually lined up in to 3, characterized in that the filler is dendritic to each other, and the organic Insulation based on silicon dioxide or silicic acid fails due to gradual creepage path formation, Specific surface area measured by the BET method has been 45 During the last few years, numerous soldering areas have been used of at least 40 m '/ g, preferably from solutions to these problems. At least they work 50 m * / g, has. the greatest of these is perhaps the training of hy- 5. Insulating materials according to claim 4, characterized by dratized aluminum oxide, preferably of the Trige, that the filler is based on hydrate, in fairly substantial amounts, for example silica or silica a specific way in butyl rubber, epoxy resin :, in particular Has a surface of 200 to 250 rri * / g. cycloaliphatic epoxy resins, and, more recently, 6. Isoliermaterialicn according to one of claims 1 in ethylene-propylene rubbers. to 5, characterized in that the »aluminum- Different theories for the mode of action of the oxide trihydrate a specific surface area in hydrated aluminum oxide was established, rich from 1 to 20 m * / g, preferably from 2 to 40, however, whichever is the right Mcchanis- 16 m '/ g. It must be stated in practice that polymers 7. Insulating materials according to one of claims 1, materials containing large proportions of aluminum oxide bis 6, characterized in that they contain a filler trihydrate, against the formation of tracking paths are protected on the basis of silicon dioxide or silica and usually only by acidic contain, which fail with a silane of the formula 45 gradual erosion of the surface. The measures required to prevent tracking RnSiX ₄ -S required amount of aluminum oxide hydrate is, however, in the η for 1, 2 or 3, R for an organic very high and is usually in the range from 50 to the remainder that via a Si-C bond to the SiIi-90 percent by weight the entire insulation. In the case of a cium atom bonded, and X represents a residue 50 of polymers which are formed by pressing or extruding which can be formed via an atom with the exception of a pressing, the high carbon atom bonded to the silicon atom causes undesirable properties,
has been treated. 1. During the shaping, at the temperatures 8. Insulating material according to claim 7, characterized by up to 200 ^c C or above, it begins to lose part of its hydrate filler dimethyldichlorosilane, Trimcthy! Chlorine water as the silane for treating the aluminum oxide hydrate. Make this water of hydration! silane, y-glycidoxypropyltrimethoxysilane, vinyltri- water vapor, which in turn leads to porous products äthoxysilan.y-Methacryloxypropyhrimethoxysilan. This must be prevented in any case because the γ-methacryloxypropyltriäthoxysilan or /? - (3,4-γ- pores, cavities or holes in an insulating material used in an epoxycyclohexylJ-ethyltrimcthoxysilane 60 has been catastrophic failure due to corona. Discharge erosion on the inside of the Cavity: 9. May cause insulating materials according to one of claims 1, wherein the cavity fell to S, characterized in that a poly finally expands until the insulation fails. Be Meres material contain, which after the pyrolysis sufficiently high voltages, the failure occurs extremely A char residue of no more than 65 quickly and can be removed in a few seconds 10 percent by weight. be closed. 10. Isolicrmalcrialien according to one of the 2. In the case of molded parts, according to the form Proverbs 1 to 9, characterized in that the environment in particular using energy