DE1544965A1 - Heated koalin containing insulating compounds - Google Patents

Description

For this application, the priority of June 9, 1964 is derived from the American patent application Serial Wo. 373 832 to claim taken.·

The present invention relates to the manufacture of electric «= see insulating compounds that contain kaolin »the temperature conditions which are below those used for mullite formation. In particular concerns the invention the use of powdered kaolin with less

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Dielectric constant and low loss factor and ver = relatively low abrasion in electrical insulation = masses. The invention also relates to the method for producing such masses

In recent years the electronics industry has had an interest in filler materials of -sXsical quality; ₉ in particular to @ i the production of cheaper Kunst.s'i.öf ρ-forraresäepturen and in the Ve? MsM ~ ang νοη Mlligeren © fvtialveE = »th fillers raifc low DielekfcrisItäfeskOHSt.envan unct ge" wrestling loss factors * inclined "the loss factor is *; <.sa essentially a measure of the electrical energy is consumed "in a body (as WSrme) due to the movement of charges IMU Bi ^ po3jnaterialien in the body when lefcafcerez" Typical Res5eptur- @ is subjected to an electric field. n _s as are of interest to the industry, range from rigid castings "for example those" which contain -phenoliseh® structural components to flexible extruded profiles, for example vinyl and butyl wire insulation.

Kaolin is an aluminum silicate with the formula AIgSI ₂ O ₁₅ (QH) ^. As such, it is used to a lesser extent in special electrical grounds where the dielectric properties are not of particular importance . However, he has a main

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the disadvantage is that it contains bound water of hydration, which gives it a high dielectric constant of around 2.5 and a high dissipation factor of around 0.16. This results in undesirable energy losses when such a material is used as a filler for high filling in a plastic insulator body.

Kaolin would be an excellent filler cheaper _r for electrical Isolatomassen if he would not have these adverse electrical »* See properties. Because of this, its value for such outlets is severely limited.

The water of hydration from kaolin can be removed by heating in such a way that all the water can be removed when a temperature of 550 - 600 ^e G is reached. By further heating to about 1000 ⁰ C, the recrystallization is carried out of the kaolin and it is in mullite, AIGSL ₂ O ₁ -, * transferred to a material with good electrical properties "that can be used as a filler of electrical quality". Because of the high heat requirement in the production of mullite, its costs are considerably higher than those of kaolin.

Another factor that needs to be considered is that Abrasive effect. When the treatment temperature of kaolin

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increases "decreases its abrasive effect and this property causes increased wear and tear on ball mills and other processing facilities. Powdered mullite is a material with a strong abrasive effect. The abrasive properties of kaolin increases quite quickly "when temperatures above 850 ° 0 are used", as can be seen in the following Values shows:

Caloinisation Sole temperature »* C index 25th 0 (approximate) 550 4th 650 8.5. 750 12th 850 22.5 950 37 * 5 1050 (mullite) 42

The grinding index is based on the Valley Abrasion Meter (Kehl-SohleifaessgerKt), with the units in ng etd. Cu loss / 100 β tone can be read

Äe 1st common practice in a factory for powdered clay the processing and shipping in por

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drove kaolin through pumps and pipelines in a factory transported in the form of an aqueous slurry »which usually some potassium hexaraetaphosphate contains "which of the Aufsehltönmung gives a disperse nature.

According to the present invention, it has now been found "that it is possible." to produce an excellent PQllsfcoff from powdered kaolin * which is valuable for the production of electrical insulation compounds with low dielectric constant and low dissipation factor, ie with values in the vicinity of about 1 * 25 - t »3O * or 0 * 005 - 0 * 020 . This is not to Mullitstufe _s obtained by calcining but by the kaolin, an "annealing ^ -Erhitzen in the range of 700 ⁰ G to 800 ⁸ C is subjected. This temperature is well above the temperature range of complete dehydration of kaolin * is however still in a heating range * in which the shower effect of the kaolin has not reached an excessively high value.

Inconveniently the thus annealed kaolin was found in the / _a processing so that the heat-treated kaolin, deterioration by contact with liquid water and, in particular, and even more serious liquid by contact with

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Water containing slurry chemicals suffers. It is therefore very important »that liquid water, and in particular Water containing suspension chemicals »from this material is kept away.

The following examples illustrate the invention without excluding it restrict:

example 1

A sample of Georgia kaolin, which is practically free of moncmorlllonite with an average particle size of about 4 α subjected to heating at different temperatures, and the dielectric properties of the product obtained were measured. In Table X are the results obtained listed. Although the breakdown voltage values are included in the table, this property is not binding Criterion for evaluating the isolator mass.

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Table I. Dielek- Durohsohlags-

Pro- handling- loss voltage kV / an be T * C ment constant factor (V / nil)

A 25 * (as above- 2.62 0.16 4.76 (121) set)

B 125 * (with 125 * 0 2.46 0.15 2.76 (70) in the oven dried)

C 640 * (sealed * 1.38 0.057 2.72 (69) air-cooled)

D 690 (caleinated, 1.34 0.024 3.03 (77) air-cooled)

E 750 * (oxygenated. 1.32 0.011 4.09 (104) air-cooled)

P 800 (calclnated t, 32 0.011 2.95 (75) air-cooled)

G 860 * (cal. 1.30 0.010 3.98 (101) air-cooled)

H 1000 * (oil-cooled 1.31 0.070 3.23 ( 82) air-cooled)

It can be seen from Table I that although the kaolin is completely dehydrated at about 600 ^° C., the loss factor begins to drop below about 0.025 at about 690 ° C. At the waste storage temperature of 1000 ⁹ C, however, the loss factor increases considerably. Obviously, the recrystallization involved leads to a pronounced change

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in the surface properties as well as in the internal tension. Although the loss factor is good at 860 ° C (sample σ) is propose a significant increase in the abrasiveness of the product in this area.

The dielectric constant and the loss factor were determined according to ASTM method D 150-59 T at 1000 Hz using the disk method. The results given are based on the average of two determinations. The breakdown voltage was measured at 60 Hz on a pressed disk (17 at or 242 psi) 34 »9 mm (1 3/8") in diameter and 25 g. The results reported are an average of five determinations. As the relative humidity This test strongly influenced «all samples were measured at a relative humidity between 20% and 40 %.

Example 2

Part of sample E from example 1 was (after cooling) removed and a common Aufeohlfimmungsarbeitsung Subject to transportation through a factory. This usual The soling procedure involves mixing the kaolin with water »containing sodium hexametaphosphate. Pumps to

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Filter device, flocculation with sulfuric acid up to pH 3.7, filter, wash and dry at 125 ° C. This dried sample was named Sample I. The electrical tests were carried out on the sample and compared with those of Sample E in Example 1 j the results are given in Table II.

Tabel II Breakthrough voltage kV / mm Per Dielectric loss (V / mil) be constant factor 4.09 (104) E. 1.52 0.011 2.99 (76) I. 1.35 0.021

From Table II it can be seen that the usual slurry of the kaolin almost doubles the loss factor and the product is unsuitable for electrical insulators of high quality makes.

Example 3

Another kaolin of similar composition as Sample A, but somewhat coarser, was heat-treated at 750 * C.

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annealed and then divided into three fractions (J, K, L), the processed as follows:

Sample J was ^{calcined at 750 °} C. and air-cooled by cooling to room temperature.

Sample K was similar hitzegetempert and quenched with water (by inserting in tap water, which was free of added chemicals) and then at 125 ⁰ C dried.

Sample L was similar hitzegetempert at 750 ⁰ C, quenched with similar Vasser, and then acidified with sulfuric acid to pH 3.7, filtered, washed and dried at 125 ⁰ C. All samples were air cooled prior to measuring their electrical properties, which are given in Table III.

Table III

Per
be T * C Dielectric
city
constant loss
factor Durohsohlags-
voltage kV / mm
(V / mil) J 750 ° 1.28 0.006 2.72 (69) K 750 * 1.32 0.008 2.83 (72) L. 750 1.32 0.020 3.11 (79)

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Sample L in Table XIX is similar to Sample X in Table XI «Ss can be seen« that water adversely affects the electrical properties of the tempered kaolin, but its effects are not nearly as detrimental as those of water plus slurry chemical "as themselves." from Table II.

Example 4

A sample of kaolin with a smaller average size, which contained a naturally occurring small amount of montmorillonite (about $ 5) ^{, was heated to a tempering temperature of 750 °} C., similar to sample E, and then divided into three fractions (samples M, N and 0). Sample H was air cooled. Sample N was quenched in Hasser ", dried at 125 ° C and air-cooled, and the" sample was air-cooled, acidified "filtered" washed and dried (like Samples X and L) and air-cooled. The electrical tests were performed on the samples. The results are shown in Table XV.

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Table IV loss
factor Breakthrough
voltage kV / mm
(V / mil) Per
be Dielectric
constant. 0.030
0.083
0.27 3.19 (81)
4.17 (106)
3.03 (77) M.
N
0 1.32
1.37
1.91

From Table IV it can be seen that if a small amount There is montmorillonite in the kaolin (e.g. about 1 - 10 #) the small amount of montmorillonite the damaging one Effect of quenching with water enhanced so that it is two-way, the montmorillonite content is as low as possible, preferably below about 10 wt. ° # or even 5 Qew.- £. Although, the water is a stronger one Damage to the electrical properties as in the case of practically inducing montmorillonite free kaolin is in In this case, the extremely harmful effect of the Auf-Bohlämaungchemicals can be seen.

From the above it can be seen that kaolin has unusually good electrical properties and with minimal Abrasive action by heating the kaolin to a

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Tempering temperature of 700 ⁶ C - 80O ⁰ C and subsequent air cooling of the clay and avoidance of contact with liquid water, especially with aqueous suspension solutions; can be produced. .

The kaolin tempered according to the invention can be used as a filler for plastic insulator compounds in amounts of about 1.0 % to about 10 %, or 30 % to 40 % and even 50 % or even up to 80 # or flour ', based on the weight »depending on the requirements of the recipe.

Examples of such formulations are as follows: Example 5

A phenolic insulator resin was made by mixing made of the following components:

Parts by weight

Phenol-Formaldehyde-Pormharζ from

electrical quality 105

Denatured alcohol 2ÖÖ

Annealed kaolin

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The mixture is ground "then heated" until the alcohol has evaporated and then ^{molded at about 230 °} C (450 ^° F) under high pressure. The above compound results in insulation properties which are at least as good as the usual insulating fillers instead of the tempered kaolin.

Example 6

Flexible vinyl insulation was made by mixing the following » the components made:

Parts by weight

Polyvinyl chloride resin from

electrical quality 60

Diootylphtnalatweiohmaeh © r 40

Basic lead complex "

silicate and silica gel 5

Annealed kaolin 10

The mixture is ground hot and at 160 ⁰ C (520 ⁰ F) _; extruded «The electrical insulation behavior is increased _; ^ _{r at} least as good as the usual insulating fillers obtained with similar masses.

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Example 7

Flexible butyl wire insulation was made by mixing the following ingredients:

Parts by weight

Butyl resin, wire insulation

variety 100

M-mefchyl-N-4-dinitrosoaniline 1

Stearic acid 1

Annealed kaolin. 60

Russ 4Ö

Zinc oxide 5

Anti-stick guard 5

Ν, Ν ¹ -Bis-1-ethyl-3-methylpentyl-pphenylenediamine 1,2

Sulfur 2

Benzothiazyl disulfide 1

Zinc dibenzyl dithiocorbamate 1.5

Zinc dibutyl dithiooarbamate 1

The mixture is ground and extruded at 16O ° C (520 ⁰ P). The electrical behavior of this Gemisohes is similar to the usual electrical insulating masses.

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Claims (1)

15U965 Georgia Kaolin Company Claims Claims / 1./Electrical insulation with low dielectric constant and low loss factor "which does not cause high abrasion, characterized by an insulating plastic ^{compound and a filler" which contains a powdered kaolin "which is heat-tempered at about 700 9} C to about 800 * C" air-cooled and in the absence of up-. BohlMmmungBchemikallen was processed. 2. Electrical insulation compound with low dielectric constant and low loss factor "which does not cause high abrasion" characterized by an insulating synthetic compound and a filler "which contains a powdered kaolin" which does not contain more than 10 % montmorillonite "and at around 700 to 800 * C hitregetenpert, 909824/1200 air cooled and in the absence of slurry chemicals has been processed. j5. Electrical insulating compound with low dielectric constant and low loss factor, which does not result in high wear and tear, characterized by an insulating «; Does not "having morillonit, and at about 700 to about 800 ⁰ C heat» plastic compound and a filler which contains a powdered kaolin * above about 10% Mont tempered, air-cooled and was processed in the absence of water and AufschlMmmungschemlkalien. 4. A process for the production of an electrical insulation compound with a low dielectric constant and a low loss factor, which does not involve high abrasion, characterized in that a powdered kaolin is ^{heated to a tempering temperature of about 700 to about 800 e} C until the above-mentioned electrical characteristics remain practically constant, the tempered product is cooled in the air and then the cooled product as a filler directly in a plastic insulation compound * without prior contact with liquid water or insulation chemicals in one - "■ 17 - . . BATH ORIGINAL 809824/1200 At aqueous medium. 5. The method ziir producing factor of an electrical insulating material with low dielectric constant and low-loss ", which brings to high abrasion with it, characterized in that one heats a gepulverten.Kaolin to an annealing temperature of about 700 ⁰ C to about 800 ° C * to the above-mentioned electrical properties remain practically constant, this tempered product is cooled in the air and then the cooled product is introduced as a filler directly into a plastic insulation compound, without prior contact with insulation chemicals in an aqueous medium. 6. A method for producing an electrical insulating material with low dielectric constant and low dissipation factor, · who do not have high abrasion entails de "characterized by, that a powdered kaolin, cer no more than about 10 wt -. Containing% Montmorillonlt, an annealing temperature heated from about 700 ^e C to about 800 ° C until dle _x aforementioned electrical properties substantially remain constant, then air-cooled heat-treated product of this and previous anechliessend this cooled product as a filler directly into a Kunststoffisolierverbindung without - 18 - 909824/1200 Contact with insulation chemicals in an aqueous solution Medium. - 19 - 909824/1200