KR101252593B1 - Production of electrical insulation and insulated products - Google Patents

Abstract

The present invention relates to a method (100) for manufacturing electrical insulators for medium or high voltage equipment.
The method 100 includes pressurizing (101) all liquid components of the insulating material of the electrical insulator through a static mixer, adding (102) at least one filler to the component, and adding the component to at least one Pressing 103 the component having at least one filler into the final mixture of insulating material through a tube comprising a high speed-rotating screw mixing device mixing with the filler and guiding the final mixture into a mold for vacuum casting ( 104b), wherein the mold is located in a vacuum chamber, the inlet of the vacuum chamber being connected to an outlet of a mixing device fluidly connected to the mold, the guiding step 104b, and at least partially curing the final mixture Forming 105 an insulator; and molding 106 an electrical insulator. Curing may be part of the molding.

Description

PRODUCTION OF ELECTRICAL INSULATION AND INSULATED PRODUCTS}

The present invention relates generally to electrically insulating articles and in particular to high or medium voltage articles. This document relates in particular to the manufacturing process of insulating products, for example barrier insulators.

The present invention relates to a method for producing an electrical insulator and to an electrical insulator produced by the method according to the independent claim.

In the electronics industry, thermosetting insulating materials are used to produce the medium voltage (MV) embedded poles and other insulation of, for example, dry type distribution transformers. Mixing largely filled insulating materials takes considerable time, often over 1 hour. The standard process involves mixing resin and filler separately and mixing of hardener and filler in two pots equipped with an impeller mixer to prevent premature reaction. After good filler dispersion is achieved in the two components, these components are simultaneously forced through a so-called static mixer and injected into the mold.

Molding principles include conventional vacuum casting or automatic pressure gelation; It is also a process that can be vacuum assisted.

Several reliable mixing systems for producing pourable compounds are commercially available from, for example, a Hedrich vacuum system and Huebers Verfahrenstechnik.

It is an object of the present invention to provide an improved and effective method for producing electrical insulators.

This object is achieved by accelerating the production process by using different mixing processes for treating the insulating material. Instead of using a conventional system comprising a separate container for resin and hardener with an impeller mixer, the system of the present invention is based on a high speed rotating conveying screw.

According to one embodiment of the invention, a method of manufacturing an electrical insulator for a medium voltage or high voltage device is provided, the method comprising forcing all liquid components of the insulating material of the electrical insulator through a static mixer; Adding a component having at least one filler to the final mixture of insulating material through a tube comprising adding at least one filler to the component and a high-speed screw mixing device for mixing the component with the at least one filler. Pressurizing, guiding the final mixture into the mold through an outlet of a mixing device fluidly connected to the mold, forming an electrical insulator by at least partially curing the final mixture, and Molding.

According to another embodiment of the present invention, a method of manufacturing an electrical insulator for a medium voltage or high voltage device is provided, the method comprising pressurizing all liquid components of the insulating material of the electrical insulator through a static mixer, and Adding one filler to the component and forcing the component having at least one filler into the final mixture of insulating material through a tube comprising a high-speed screw mixing device for mixing the component with the at least one filler. Guiding the final mixture to a mold for vacuum casting, the mold being located in a vacuum chamber, the inlet of the vacuum chamber being connected to an outlet of a mixing device fluidly connected to the mold; Forming an electrical insulator by at least partially curing the final mixture; And a step of coding.

The aforementioned curing may be part of the molding.

와 같은 풀러(Fuller) 분포를 갖는 풀러 시브 곡선(Fuller sieve curve)에 따르고,According to another exemplary embodiment, a method according to the embodiments mentioned above and below is provided, wherein at least two fillers are added to the component and the mixing ratio of the fillers of the insulating material is

According to the fuller sieve curve with a fuller distribution such as

Where d is the particle size of the filler, D is the maximum particle size, for example 300 μm, P is the particle ratio of d or less, n is the coefficient of curvature, perhaps 0.37 or 0.5.

The fuller sheave curve describes the optimized filler composition of the mixture that provides the optimized strength of the mixture and the optimized properties of the mixture, such as porous or hollow.

By optimizing the composition of the two fillers in accordance with the aforementioned puller distribution, the miniaturization of the insulator produced can be optimized, providing an ideal relationship between the filler and the component / matrix.

The component may comprise a curing agent and a resin.

Instead of using a batch mixer, a continuous mixer with very high shear stress is used. High shear stresses significantly reduce the mixing time compared to conventional impeller mixers, which generally have a low shear stress resulting from slightly longer procedures and mix dispersions of fillers in resins and hardeners.

The insulating material may be a standard filled epoxy, generally silica, having a filler content of about 65 wt%, corresponding to about 44% by volume, for example, one filler size. The insulating material may comprise polymer concrete.

According to another embodiment of the present invention, at least two fillers may be used, such fillers being from 70 to 96 wt%, corresponding to about 49 to 91 volume%, generally from 83 to 85 corresponding to about 60 to 70 volume% has a filler content of wt%. Polymer concrete can be used for each filler.

By applying higher shear stress, the time required to mix the dispersion of filler in the resin and hardener can be reduced by at least a factor of 10 compared to prior art devices such as impeller mixers, since the mixing efficiency is greatly increased. Fillers, resins and hardeners can be seen as components of the insulating material of the electrical insulator.

According to one embodiment of the present invention, a method of manufacturing an insulator for an intermediate voltage or high voltage device is provided, wherein the material is pressed inside a high speed rotating screw through a tube, such as a cylindrical tube, which causes high shear stress, This results in good dispersion of the filler in the matrix of the material. The components pass through a mixing screw that includes a thin film degassing unit in less than one minute. The force of high shear stress generated by the system allows for a higher filler content, which can be achieved by applying more than one filler.

Moreover, the method of the present invention contributes to the following advantages:

Significantly reduced mixing time, and thus increased production throughput

Reduced risk of filler particle precipitation, and better dispersion

Higher filler content, and thus reduced cost (up to 85 wt% silica has been demonstrated experimentally, and higher solids content is probably achieved by using a larger number of different fillers and larger maximum filler grain sizes).

Low material loss due to relatively low volume of restricted mixing channels

Possibly abrasion: The mixing screw is made of a special wear protection alloy so that wear fillers such as alumina can be treated with it.

Further embodiments, advantages and applications of the present invention will become apparent from the claims or combinations of claims from the following detailed description and drawings.

The subject matter of the present invention will be explained in more detail in the following description with reference to exemplary embodiments shown in the accompanying drawings which are schematically shown.

The method of the present invention contributes to the following advantages:

Significantly reduced mixing time, and thus increased production throughput

Reduced risk of filler particle precipitation, and better dispersion

Higher filler content, and thus reduced cost (up to 85 wt% silica has been demonstrated experimentally, and higher solids content is probably achieved by using a larger number of different fillers and larger maximum filler grain sizes).

Low material loss due to relatively low volume of restricted mixing channels

Possibly abrasion: The mixing screw is made of a special wear protection alloy so that wear fillers such as alumina can be treated with it.

1 is an optical micrograph showing a first sample of polymer concrete mixed with a conventional impeller type mixer.
2 is an optical micrograph showing a second sample of polymer concrete mixed with a conventional impeller type mixer.
3 shows an overview of an optical microscope (scanning electron microscope) of a sample of polymer concrete of the present invention mixed with a continuous screw mixer in accordance with an exemplary embodiment of the present invention.
4 is an enlarged (IV) view of the scanning electron microscope shown in FIG. 3 in accordance with an exemplary embodiment of the present invention.
5 is a schematic diagram of a puller sheave curve with examples of different fillers.
6A is a flow chart illustrating a method of manufacturing an electrical insulator for a medium voltage or high voltage device in accordance with an exemplary embodiment of the present invention.
6B is a flow chart illustrating a method of manufacturing an electrical insulator for a medium voltage or high voltage device in accordance with another exemplary embodiment of the present invention.

Differences in the technical effects of the present invention will become apparent when comparing micrographs of polymer concrete produced by the method according to the present invention and micrographs of polymer concrete produced by conventional production methods using impeller-type mixing devices.

When focusing on FIG. 1 displaying an optical micrograph of a first sample of polymer concrete mixed with a conventional impeller mixer, essentially three distinguishable areas can be identified. Reference number 1 represents a large silica filler particle having a conventional average diameter of 0.3 mm, while reference number 2 represents a void, and reference number 3 a small silica having a conventional average diameter of 0.016 mm. The area with filler particles and the epoxy matrix are shown. In particular, the particles 1 and the voids 2 have slightly larger dimensions.

Large pore dimensions cause partial discharge when the insulating material is subjected to a high electric field, which can lead to degradation of the material during the lifetime of the insulated product.

Most commonly, the insulation configuration consists of epoxy resins, hardeners, catalysts, fillers, and other liquid or solid additives. Existing filler content may be 65wt%.

Likewise, the situation in FIG. 2 displays an optical micrograph of a second sample of polymer concrete produced by mixing of the components by a conventional production method using an impeller-type mixing device. The difference of the second sample compared to the first sample shown in FIG. 1 is that the pore content can be greatly reduced by applying a combination of vacuum gas removal and vibration. Again, essentially three distinguishable regions can be identified.

Reference numeral 4 denotes a resin-rich region having a very low filler content, while reference numeral 5 denotes a large filler particle {compared to reference numeral 1 in FIG. 1), and reference numeral 6 Denotes an area with small silica filler particles and an epoxy matrix (relative to reference number (3) in FIG. 1). Particles 4 and 5 in particular have slightly larger dimensions. Again, non-uniform compounds may experience long-term degradation when subjected to high electric fields.

A scanning electron micrograph of a first sample of polymer concrete mixed with the production method of the present invention according to the present invention is shown in FIG. 3. Although the scale of the micrograph is 500 μm (micrometer), relatively large silica particles 1 are easily identified (relative to reference numeral 1 in FIG. 1). Reference numeral 3 denotes an area having a small silica filler particle (compared to reference numeral 3 in FIG. 1) and an epoxy matrix. Moreover, the area indicated by arrow IV is included in FIG. 3. The area IV is an enlarged view of the reference numeral 3 and will be explained in FIG. 4.

For the components required to produce such polymer concrete, reference is made to example 5, which is described in detail later. Pressing the mixture through a cylinder comprising a high-rotational screw mixing device to produce a final mixture results in a shear stress modulus in the range of about 20 to 30 GPa, and a Young's modulus upon compression of about 30 to about 40 GPa. Cause.

An enlarged view of the region IV shown in FIG. 4 shows a diameter of 0.004 mm in which the region 3 surrounds the large particles 8 in the range of 0.016 mm diameter and the particles 9 in the range of 0.06 mm diameter. It comprises a relatively large amount of small filler particles 7 in the range. High shear stress applied to the mixture during the mixing step results in a uniform distribution of particles. During this step, the mixture is pressurized through a cylinder comprising a continuous high-rotational screw mixing device and a thin film degassing unit resulting in a material having a very low pore content to produce the final mixture. Dark portion 10 in FIG. 4 represents an epoxy matrix.

5 schematically shows a fuller sheave curve. The fuller sheave curve of FIG. 5 shows the proportion of fillers of different sizes to obtain dense packed concrete as follows:

d is the particle size, D is the maximum particle size, 300 μm according to FIG. 5, P is the particle ratio of d or less, and n is the curvature coefficient. For round particles, n is typically set to 0.5 and for crushed particles, to 0.37 (Fuller WB, Thompson SE, The laws of proportioning concrete, Transactions of the American Society of Civil Engineers. Article No. 1053, 1907). , pp 67-143). 600 EST, W12 EST, W3 and Sihelco 30 are different fillers with different particle proportions.

The fuller sheave curve describes the optimized filler composition of the mixture that provides the optimized strength of the mixture and the optimized properties of the mixture, such as porous or hollow.

FIG. 6A shows a flow diagram of a method 100 of manufacturing an electrical insulator for an intermediate voltage or high voltage device, the method comprising pressing 101 all liquid components of the insulating material of the electrical insulator through a static mixer; Adding at least one filler to the component (102) and a tube having at least one filler through a tube comprising a high-speed screw mixing device for mixing the component with the at least one filler to finalize the insulating material. Pressurizing the mixture (103), guiding the final mixture into the mold through an outlet of a mixing device fluidly connected to the mold (104a), and forming an electrical insulator by at least partially curing the final mixture. 105, molding 106 the electrical insulator, degassing the final mixture by the gas removal unit 107, In part, the final mixture in the outer mold post - and a step 108 of curing (post-curing).

6B provides a method 100 of manufacturing an electrical insulator for a medium voltage or high voltage device, the method comprising pressurizing 101 all liquid components of the insulating material of the electrical insulator through a static mixer, at least Adding at least one filler to the component (102) and a tube comprising a fast-rotating screw mixing device for mixing the component with the at least one filler to convey the component having at least one filler to the final mixture of insulating material. Pressurizing (103) and guiding the final mixture into a vacuum casting mold (104b), wherein the mold is located in a vacuum chamber, the inlet of the vacuum chamber being an outlet of the mixing device fluidly connected to the mold. Guiding step 104b, forming an electrical insulator by at least partially curing the final mixture, and driving the electrical insulator. And step 106 for the step of the final mixture by a gas removal unit to remove gas 107, a post the final mixture in the outer mold, at least in part - a step (108) for curing.

Method of performing the present invention

Various ways of possible embodiments of the method of the invention are described and discussed later by way of example.

Example 1 (aromatic epoxy composition)

The epoxy resin composition is made of the components given in Table 1. The components were mixed in different mixing devices (two different production-size impeller mixers, and a production-size continuous screw mixer). The mixing time was recorded, the secondary plate (150 × 150 mm) of about 4 mm thick was cast and cured at about 80 ° C. for about 8 hours and post-cured at about 140 ° C. for about 4 hours. Samples for mechanical testing were processed among these plates and tested according to the standards given in Table 2. Five samples were tested as appropriately described.

The production-sized impeller mixer included two separate mixing containers equipped with impellers for epoxy resins and anhydride hardeners. In these containers, the filler is dispersed in a resin and a hardener, respectively. These two components are then pressurized through a static mixer.

In a continuous screw mixer, the epoxy composition is formulated by volumetric dosage of the liquid component through a static mixer. The filler is then added and dispersed by pressurizing all the components through a cylindrical tube equipped with a high-speed rotating screw including a thin film degassing unit.

Raw material composition for aromatic epoxy composition (material is given in phr, ie percentage of epoxy resin) type Brand name producer phr Epoxy resin Epikote EPR 845 Hexion (DE) 100 Anhydride hardener Epikure EPH05389 Hexion (DE) 84 Silica filler W12 Quarzwerke (de) 320

Comparing impeller mixers A and B, it was observed that impeller mixer A produces better results after about 240 minutes of mixing than impeller mixer B after about 480 minutes of mixing. A slight increase in mechanical properties at mixing time was observed for impeller mixer B.

As can be seen from Table 2, continuous screw mixers result in superior mechanical properties compared to both impeller mixers. Even at very long mixing times of about 480 minutes, the mechanical properties of continuous screw mixers cannot be reached. The mechanical property is the filler dispersion function in the matrix material, which in turn depends on the mixing efficiency. The mixing efficiency depends on both the mixing time and the mixing geometry. Continuous screw mixers produce very high shear stress, and thus very short mixing times, in the range of about 1 minute, compared to impeller mixers, which leads to good dispersion.

Mechanical test results of aromatic epoxy treated with different mixing devices characteristic Standard Impeller Mixer A Impeller Mixer B Impeller Mixer B Impeller Mixer B Continuous screw mixer Mix time (minutes) 240 15 30 480 One Young's modulus at the bend (GPa) ISO 178, 10.9 ±
0.1 10.8 ±
0.1 11.1 ±
0.2 10.9 ±
0.2 11.4 ±
0.3 Flexibility Strength (MPa) ISO 178, 144 ± 4 122 ± 6 123 ± 9 127 ± 7 159 ± 3 Elongation at break (%) ISO 178, 1.57 ±
0.08 1.21 ±
0.07 1.20 ±
0.11 1.29 ±
0.11 1.70 ±
0.05

Examples 2-4 ( Filled Cycloaliphatic  Epoxy and Polymer  Production of insulators from concrete)

The epoxy resin composition (Table 3) is made of the components given in Table 4.

The epoxy composition is formulated by volume dose of the liquid component through a static mixer. The filler is then added and dispersed by pressurizing all the components through a cylindrical tube that includes a high speed rotating screw that also includes a thin film degassing unit. The retention time of the material in the screw is generally in the range of less than one minute. The outlet of the mixing tube is directly connected by a hose to a heated steel mold mounted on a hot-press. The steel mold is for medium voltage outdoor insulators. The mold on the hot-press is at 125 ° C. After injection and a further 2 hours of curing, the part is unmolded.

Examples of compositions (materials are given in phr, ie percentage of epoxy resin) material Example 2 Example 3 Example 4 Ardldite
CY184 100 100 100 Aradur HY1235 90 90 90 DY062 0.54 0.54 0.54 Silbond W12 EST 354 354 354 Sihelco 30 576 726 Filler content (wt%) 65 83 85

Raw Material for Cycloaliphatic Epoxy Components type Brand name producer Cycloaliphatic epoxy resins Ardldite CY184 Huntsman advanced
Materials (CH) Anhydride hardener Aradur HY1235 Huntsman advanced
Materials (CH) accelerant DY062 Huntsman advanced
Materials (CH) Silica powder Silbond W12 EST Quarzwerke (de) Silica sand Sihelco 30 Sihelco (ch)

Example 5 (larger Filled Polymer  Homogeneous mixture of concrete)

The polymer concrete composition (Table 5) is made of the components given in Table 6. Four silica fillers of different sizes were selected according to the fuller sheave curve to obtain a packed filler packing. This results in improved mechanical properties, reduced settling risk, reduced material cost, and increased thermal conductivity.

This example evaluates filler dispersion for two dispersion methods: a lab-scale impeller mixer and a production-size continuous screw mixer. For the lab-scale impeller mixer, the components were mixed until a homogeneous mixture was obtained (typically 30 to 60 minutes). The mixing was then degassed to 5 mbar and cast into a plate mold providing a 6 mm thick plate. The plate was cured at 90 ° C. for 2 hours and at 140 ° C. for 10 hours. Mixing processes for continuous screw mixtures are described in Examples 2-4. Small samples were cut from the plates and prepared for the microscope. The sample is characterized by optical and scanning electron microscopy.

Examples of compositions (materials are given in phr, ie percentage of epoxy resin) material Example 5 Araldite CY184 100 Ardadur HY1102 90 DY070 0.3 Silbond 600 EST 66 Silbond W12 EST 131 Millisil w3 312 Sihelco 30 569 Filler content (wt%) 65

Raw Materials for Cycloaliphatic Epoxy Compositions type Brand name producer Cycloaliphatic epoxy resins Araldite CY184 Huntsman advanced
Materials (CH) Anhydride hardener Aradur HY1135 Huntsman advanced
Materials (CH) accelerant DY070 Huntsman advanced
Materials (CH) Silica powder Millisil w3 Quarzwerke (de) Silica powder Silbond W12 EST Quarzwerke (de) Silica powder 600 EST Quarzwerke (de) Silica sand Sihelco 30 Sihelco (ch)

Claims (14)

A method (100) of manufacturing an electrical insulator for a medium voltage or high voltage device,
Pressurizing (101) all liquid components of the insulating material of the electrical insulator through a static mixer;
Adding at least one filler to the component (102),
Pressing (103) the component with at least one filler onto the final mixture of insulating material through a tube comprising a high-speed screw mixing device for mixing the component with the at least one filler;
Directing the final mixture to the mold through an outlet of a mixing device fluidly connected to the mold (104a),
Forming an electrical insulator by partially curing the final mixture (105),
Molding 106 the electrical insulator
A method of making an electrical insulator for a medium voltage or high voltage device, comprising. A method (100) of manufacturing an electrical insulator for a medium voltage or high voltage device,
Pressurizing (101) all liquid components of the insulating material of the electrical insulator through a static mixer;
Adding at least one filler to the component (102),
Pressing (103) the component with at least one filler onto the final mixture of insulating material through a tube comprising a high-speed screw mixing device for mixing the component with the at least one filler;
Guiding the final mixture to a mold for vacuum casting (104a), wherein the mold is located in a vacuum chamber, the inlet of the vacuum chamber being connected to an outlet of a mixing device fluidly connected to the mold; )Wow,
Forming an electrical insulator by partially curing the final mixture (105),
Molding 106 the electrical insulator
A method of making an electrical insulator for a medium voltage or high voltage device, comprising. The method of claim 1, wherein the mold is part of a vacuum chamber. 3. The method according to claim 1 or 2,
Degassing the final mixture by a degassing unit (107),
And said high speed-rotating screw mixing device comprises a gas removal unit. 3. The method of claim 1, wherein the curing is performed in part in a mold. 4. A method according to claim 1 or 2, wherein the curing is carried out completely in the mold. 4. The medium voltage or high voltage appliance of claim 1, further comprising post-curing the final mixture in a convection oven that is partially pressurized outside the mold. A method of manufacturing an electrical insulator for the invention. The method according to any one of claims 1 to 3, wherein at least two fillers are added to the component, and the mixing ratio of the filler of the insulating material is

Following a Fuller sieve curve with a Fuller distribution of
Wherein d is the particle size of the filler, D is the maximum particle size, P is the particle ratio less than or equal to d, and n is the coefficient of curvature. 4. The method of any one of claims 1 to 3, wherein pressurizing the mixture through the tube is such that the high-rotational screw mixing device mixes the component having at least one filler with the final mixture, thereby providing 2-40 GPa. Causing a Young's modulus at the bend in the range of. 4. The method of claim 1, wherein the volume of at least two fillers comprises at least 49% of the volume of insulating material of the electrical insulator. 5. 9. A method according to claim 8, wherein the proportion of filler is determined according to a curvature factor n of 0.5. 9. A method according to claim 8, wherein the proportion of filler is determined according to the curvature coefficient n of 0.37. Electrical insulator for medium voltage or high voltage equipment manufactured according to the method (100) according to any one of claims 1 to 3. The method of any one of claims 1 to 3, wherein pressurizing the mixture through the tube is characterized in that the high-rotational screw mixing device mixes the component having at least one filler with the final mixture, thereby providing 10-30 GPa. Causing a Young's modulus at the bend in the range of.

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