JPS6252813A - Mica sheet - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a mica sheet insulating material used in home appliances, and particularly to one with improved corona resistance.

BACKGROUND OF THE INVENTION Various electrical components are used in household electrical appliances, and each electrical component uses an electrically insulating material. For example, a transformer has a coil winding wound around an iron core, and the windings are insulated from each other, as well as between the winding and the iron core.

Conventionally, as the insulator between the winding wire and the iron core, a laminated aramid fiber (polyamide fiber) called Nomex (trade name) or a sheet made by heat-sealing the aramid fiber (polyamide fiber) has been used.

However, this Nomex not only has a problem with its corona resistance properties, but also has a problem with its workability in bending it into the shape of an iron core when it is wound around an iron core because of its high rigidity.

In order to improve corona properties, it is not possible to use materials conventionally used as insulating materials for heavy electrical machinery, such as mica tape and mica sheets, which are made by pasting paper-made mica pieces onto glass fiber cloth with adhesive. However, the process of paper-making mica pieces and pasting mica pieces sheets with adhesive increases manufacturing costs, making it more expensive than the Nomex mentioned above, and currently it is not widely used. not being used.

Problems to be Solved by the Invention As explained above, there is room for improvement in the corona resistance and processability of conventional insulating materials used in transformers, for example.
Mica tapes and the like used in heavy electrical machinery have the problem of high cost, and an improvement has been desired.

Means for Solving the Problems In order to solve the above problems, the present invention provides a mica sheet comprising a base material and a mica layer made of at least mica and a resin provided on the surface of the base material. It provides:

Next, the present invention will be explained in detail.

Heat-resistant materials are used for the base material used in the present invention, such as glass fiber woven fabric, glass fiber non-woven fabric, polyamide non-woven fabric such as aramid, fabric made from aramid and heat-fused, and polyester fabric. and sheets, polyimide films, polyamideimide films, etc. Among these, thermosetting modified polyester resins, silicone resins, epoxy resins and the like can be used as adhesives for producing nonwoven fabrics, but are not limited to these. In particular, silicone resin is preferable because its upper limit temperature for use is 180° C. or higher.

Each of the above materials can be used alone, but they can also be used in various combinations, such as a structure in which aramid nonwoven fabric is laminated on both sides of glass fiber nonwoven fabric.

Further, the mica layer in the present invention is made of at least a mica material such as mica powder or mica pieces and a resin. The mica may be either an unfired type or a fired type, or both may be used in combination. The resin used for the mica layer is the same as the resin used for the base material.

The ratio of the above mica material and resin is 20:80 to 20:80 in parts by weight.
8Q:20 is mentioned. If the amount of mica material is larger than this, the resulting mica sheet will lose its flexibility and will have poor workability such as bending. Moreover, if the ratio of resin is too high, corona resistance will deteriorate. When using a thermosetting resin, the mica sheet should be in a semi-hardened state to make it easier to process, and after it has been specifically incorporated into a device, it should be heated to harden it. is preferred.

To form such a mica layer, mica material and resin are mixed, and this is applied directly or diluted with a solvent onto the base material using an appropriate means such as a spray nozzle, brush coater, roll coater, etc. Various methods are used, such as

The mica layer formed on the base material in this way can be used as is, but it can also be heat pressed.
Hot pressing in this manner is preferable because the structure of the base material and mica layer becomes dense.

The mica layer may be formed on one side of the base material, or may be formed on both sides. Alternatively, the mica layer may be sandwiched with a base material.

Since active mica is used, it has excellent corona resistance properties, and since the mica layer contains resin, it becomes flexible and can maintain workability well. Furthermore, since the mica layer does not require a paper-forming process, manufacturing costs can also be reduced.

Embodiment Next, an embodiment of the present invention will be explained based on FIGS. 1, 3, and 4.

What is shown in Figure 1 is a mica sheet, consisting of a glass fiber nonwoven fabric (thickness 0.10) as a base material, which is made by binding glass fibers with a small amount of epoxy resin. Mica N2 is formed by applying a ferrite film and drying it by an appropriate means.

Mica powder 30 parts by weight Modified polyester resin 30 parts by weight (Product name 1ONEL 5
1C manufactured by Nippon Shokubai Chemical Co., Ltd.) 40 parts by weight of toluene (solvent), then aramid nonwoven fabric (thickness 0.05
mm) 3 is coated with the mica powder-containing varnish and dried by an appropriate means to form a mica layer 4.

The mica layers formed on each base material in this way were combined at 180°C and 20Kgf as shown in Figure 1.
Heat press with /ad. By hot pressing in this manner, the surface becomes smooth, the air contained in each of the mica layer 2.4, the glass nonwoven fabric 1, and the aramid nonwoven fabric 3 is removed, and the structure becomes dense, so that corona resistance properties can be improved. However, if the modified polyester resin is completely cured, processability will deteriorate, so this resin is left in a semi-cured state.

In this way, mica silica was produced as an insulating material, and the results of testing its corona resistance properties were as follows.

Note that test results for Nomex 414 are also listed as a comparative example.

Test method As shown in Figure 3, the upper electrode (diameter 5 W, IEC electrode) 5 made of 18.8 stainless steel wire weighs 20 g and the lower electrode 6 made of a flat plate made of 18.8 stainless steel wire.
The sample shown in Fig. 1 (100 x 100 gm) prepared as above was sandwiched between the
A constant sinusoidal voltage is applied, and the time (hour) until the sample undergoes corona deterioration and destruction is measured.

Test results As shown in FIG.

From the results of this graph, it can be seen that the failure time of the examples was significantly longer than that of the comparative examples.

In the above, mica layers were formed and laminated on the glass fiber nonwoven fabric and the aramid nonwoven fabric, respectively, but as shown in Fig. 2 (a) T/: As shown in Fig. 2 (a), a mica layer 2 was formed on the glass fiber nonwoven fabric 1, and the same figure (b) It is also possible to use an aramid nonwoven fabric 3 with a mica layer 4 formed thereon, as shown in FIG. It is preferable that these be hot pressed, but this is not restrictive.

Effects of the Invention As described above, the present invention is composed of a base material and a mica layer, and this mica layer is composed of at least mica and resin, so that corona resistance is improved by using mica, and the mica layer is Since it contains resin, it can be easily processed such as bending, and it can also be used for #
Since it is manufactured without going through small steps, costs can also be reduced. 4,

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of a mica sheet according to one embodiment of the present invention, Fig. 2 is a cross-sectional view of a mica sheet according to another embodiment, Fig. 3 is a diagram showing a mica sheet testing device, and Fig. 4 is a cross-sectional view of a mica sheet according to another embodiment. It is a graph showing test results. In the figure, 1.3 is a glass nonwoven fabric or an aramid nonwoven fabric as a base material, and 2.4 is a mica layer. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] (1) A mica sheet comprising a base material and a mica layer made of at least mica and a resin provided on the surface of the base material.