JPS6329402B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an epoxy resin composition, and more particularly to an epoxy resin composition used in insulating a flyback transformer for a television receiver to manufacture a flyback transformer. It is well known that safety requirements for electronic components are becoming stronger and stronger these days. In particular, flyback transformers (hereinafter referred to as FBTs) for television receivers were used because, at the time when color televisions began to become popular in the United States, there were many fire accidents that were thought to be caused by damage to the FBTs.
There are strict regulations regarding the flame retardancy of FBT and the insulating materials used in it. in particular,
Insulating materials for FBTs must have a flame retardancy of 94V-0 or higher according to UL Standard 94, and the FBT itself must pass a combustion test based on Appended Table 82 (94) of the Electrical Appliance and Material Control Law. Conventionally, heat-curable liquid epoxy resin compositions with excellent electrical properties and adhesive properties have been used as impregnation and insulation coating forming resins for FBT.
However, the epoxy resin itself is essentially a combustible material because it is a polymeric material having a skeleton of carbon atoms, oxygen atoms, and hydrogen atoms. To compensate for this point, halogen-based flame retardants are generally used, such as
Method of blending chlorinated paraffin, hexabromobenzene, perchloropentacyclodecane, decabrom diphenyl ether, etc. Method of using halogenated epoxy resin, for example, tetrabromo bisphenol A diglycidyl ether, dibromo cresyl glycidyl ether, etc. Additionally, a method is being used in which the above-mentioned materials are used in combination with antimony trioxide or the like. However, epoxy resin compositions made flame-retardant by these methods have the disadvantage that, when burned, they generate a large amount of harmful gas containing hydrogen halide as a main component and generate a large amount of black smoke. Furthermore, since most halogen flame retardants and antimony trioxide are harmful to the human body, strict precautions must be taken when manufacturing, using, or disposing of these epoxy resin compositions. equipment is required. On the other hand, in terms of properties, halogenated flame retardants or halogenated epoxy resins are expensive, and if they are used in large amounts, they can reduce tracking and arc resistance, and cause magnet wires and electrodes to come loose. There are problems such as being easily corroded by halogens. The purpose of the present invention is to safely perform FBT insulation treatment without generating toxic gas when burning FBT and without corroding magnet wires or electrodes.
The object of the present invention is to provide an epoxy resin composition that has excellent dielectric and electrical properties, has a long pot life, is easy to work with, and does not cause problems when disposing of FBT. In order to achieve the above object, the inventor conducted various studies on epoxy resin compositions, and as a result, added hydrated alumina powder and red phosphorus powder to the epoxy resin, and further added an acid anhydride curing agent and a reaction accelerator. It became clear that things were good. That is, in the present invention, in an epoxy varnish consisting of 100 parts by weight of epoxy resin, an acid anhydride, and a reaction accelerator, the mixing amount of hydrated alumina powder and red phosphorus powder with respect to 100 parts by weight of epoxy resin is at point A in FIG.
The FBT obtained by this composition is characterized by having a viscosity of 2 to 70 poise at 25 °C in the composition range surrounded by B, C, D, E, F, G, and H. (1) No toxic gas is generated when FBT is burned. (2) Magnet wires and electrodes will not corrode. (3) FBT insulation treatment can be performed safely. (4) Good workability due to long pot life. (5) Since epoxy varnish has excellent dielectric properties, there is little heat generation due to dielectric loss of epoxy varnish during FBT operation, and high voltage output characteristics are stable. (6) No problems occur when FBT is disposed of. It has the above advantages. In particular, the compositions in which the mixed amounts of hydrated alumina powder and red phosphorus powder are surrounded by D, E, and J in Figure 3 have, in addition to the above-mentioned characteristics, particularly good arcing properties, which is one of the indicators of electrical insulation. This is a particularly preferred epoxy resin composition because of its excellent properties. Next, materials used in the present invention will be explained.
Epoxy resin is used in consideration of the efficiency of insulation processing work.
Liquid at 25℃ is best. The curing agent is preferably an acid anhydride compound so that the cured product exhibits good electrical properties even when mixed with hydrated alumina powder and red phosphorus powder. The reaction accelerator is preferably an amine compound. Hydrated alumina powder and red phosphorus powder are suitable for resin filling. Specifically, 100 parts by weight of epoxy resin and acid anhydride,
The mixing ratio of hydrated alumina powder and red phosphorus powder to 100 parts by weight of epoxy resin in an epoxy varnish consisting of a reaction accelerator is determined by points A, B, C, D in Figure 3,
An epoxy resin composition having a composition within the range of E, F, G, and H is preferable, especially when the mixed amount of hydrated alumina powder and red phosphorus powder is within the range of D, E, and J.
In the range surrounded by , the arc properties are particularly excellent. This is because if FBT is insulated with an epoxy resin composition having a composition outside this range, the finished FBT may have insufficient flame retardancy, or the FBT may
This is because the coil will not be sufficiently impregnated with the epoxy resin composition, making it impossible to provide void-free insulation, which may cause the FBT to break down due to partial discharge. In addition, 25% of the epoxy resin composition within the above composition range
The viscosity at °C is 2 to 70 poise. Viscosity is 2
If it is smaller than 70 poise, the flame retardancy of the completed FBT will be insufficient, and if it is larger than 70 poise, it may be due to poor impregnation.
FBT becomes possible, which is not desirable. Next, the present invention will be explained in detail with reference to Examples. Figure 1 is
An example of an FBT cross-sectional view is shown. In other words, in FBT, the primary bobbin 5, secondary bobbin 3, primary coil 6, and secondary coil 4 are assembled in the case 2, and after the high voltage lead wire 7 is pulled out from the secondary coil 4, the resin composition for impregnation and coating formation is applied. It can be manufactured by casting the product 1. Epoxy resin compositions having the compositions shown in the composition columns of Examples 1 to 11 in Table 1 were applied to the coil portion of the FBT shown in Figure 1 from above at a temperature of 20 to 30°C.
Vacuum injection was performed at a vacuum degree of 2 to 4 mmHg, and the temperature was 60℃/
The epoxy cast FBT was obtained by heating and curing under the conditions of 4 hours + 105°C/7 hours. A flame retardancy test was conducted on each of the epoxy cast FBTs obtained in this way based on the Electrical Parts Control Law by applying the oxidizing flame 9 of the gas burner 8 to the lower part of the case 2 as shown in Figure 2. As shown in the characteristics and flame retardance column of FBT of Examples 1 to 11, all passed the test. Further, the amount of smoke generated during combustion was small as shown in the FBT characteristics of Examples 1 to 11 in Table 2, and the amount of smoke generated during combustion column. Next, the epoxy cast FBT was cut as shown in Figure 1, and the impregnability of the epoxy resin and the presence or absence of voids in the coil were observed. As shown in the presence/absence column, all were good. Furthermore, an epoxy resin composition having the composition shown in the composition column of Examples 1 to 11 in Table 1 was prepared at 60°C/4h+105
Cure at ℃/7h, flame retardant, tracking resistance,
When the arc resistance was investigated, as shown in the properties column of the resin composition in Table 2, the flame retardance was V-0,
The tracking resistance was 600V or more in all cases, and the arc resistance was 120 to 180 seconds, which were also good. In particular, the epoxy resin compositions of Examples 3, 8, and 9 all exhibited very good arc resistance values of 180 seconds. In addition, the dielectric properties of resin plates with a thickness of 2 mm produced by curing the epoxy resin compositions having the compositions shown in the composition columns of Examples 1 and 2 in Table 1 under the above-mentioned curing conditions were investigated, and the results are shown in Table 3. As shown in Examples 1 and 2, good values were shown both at high temperatures and when absorbing moisture. Although not shown in Table 3, Examples 3-
Similarly to Examples 1 and 2, Sample No. 11 also showed good values.

【table】

【table】

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[Table] In addition to operating normally as an FBT, it maintained good characteristics for a long time even when operated under harsh temperature and humidity conditions. Although not described in the examples, it is also possible to incorporate various additives into the epoxy resin composition of the present invention, such as antifoaming agents, voltage stabilizers, colorants, surfactants, etc. . In addition to the methods shown in Figure 1, FBT methods include those with interlayer insulation using plastic film, diodes, resistors,
By connecting capacitors etc. inside, miniaturized and multi-purpose FBT, using a mold without using a case,
It can also be applied to dip coat type FBT, etc. Comparative Example First, an epoxy resin composition having the composition shown in the composition columns of Comparative Examples 1, 5, and 6 in Table 4 was cast.
FBT has a low content of red phosphorus powder and hydrated alumina powder, so as shown in the FBT characteristics and flame retardance column of Comparative Examples 1, 5, and 6 in Table 2, it has insufficient flame retardancy as FBT, and Does not pass the Parts Control Law. FBT cast with epoxy resin having the composition shown in the composition columns of Comparative Examples 2, 3, and 4 in Table 3 has low flame retardancy because it contains a large amount of hydrated alumina powder and red phosphorus powder. , Table 2 Comparative Examples 1, 5, and 6
As shown in the FBT properties and flame retardance column, it shows sufficient properties, but the fluidity of the resin composition is poor, air entrainment occurs during injection, and it is difficult for air to escape.
Table 2 Properties of FBT of Comparative Examples 2, 3, and 4, impregnation properties,
As shown in the presence/absence of voids in the coil column, voids remain within the coil, making it impossible to obtain a long-life FBT.
The epoxy resin composition shown in the composition column of Comparative Example 9 in Table 4 is obtained by replacing the hydrated alumina of the epoxy resin composition shown in the composition column of Example 4 in Table 1 with silica powder. However, I cast it with this
FBT had insufficient flame retardancy, as shown in the characteristics and flame retardance column of Comparative Example 9FBT in Table 2. moreover,
The epoxy resin composition shown in the composition column of Comparative Example 10 in Table 4 is made flame retardant by the conventional method, that is, by blending a halogen flame retardant and antimony trioxide. Characteristics: As shown in the combustible smoke generation column, a large amount of black smoke and toxic gas are generated during combustion, and Examples 1 to 4 in Table 1
The epoxy resin composition shown in the composition column was heated at 60℃/4h.
It had drawbacks such as inferior tracking resistance and arc resistance compared to those cured at +105°C/7 hours, and was not preferred in practice. Furthermore, the epoxy resin compositions shown in the composition column of Comparative Examples 7 and 8 in Table 4 are examples in which an amine compound is used as a curing agent, but as shown in Comparative Examples 7 and 8 in Table 3, It has poor dielectric properties when absorbing moisture, and as shown in the impregnability and presence/absence of voids in the coil column of Comparative Examples 7 and 8 in Table 2, the impregnability is poor and voids occur in the FBT coil. It was hot.

[Table] As described above, according to the present invention, no harmful gas is generated during FBT combustion, magnet wires and electrodes do not occur, and the electric performance is excellent.
It is possible to efficiently manufacture a long-life FBT that does not cause problems when disposing of the FBT.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of FBT, Figure 2 shows the FBT flame retardant test method based on the Electrical Appliances and Materials Control Law Act 82 (94), and Figure 3 is an epoxy resin composition for impregnation and coating formation. This figure shows the relationship between the amount of red phosphorus powder hydrated alumina blended into the material and FBT characteristics. 1...Resin composition for impregnation and coating formation.

Claims (1)

[Claims] 1. Epoxy resin of epoxy varnish consisting of 100 parts by weight of epoxy resin, acid anhydride, and reaction accelerator
The mixing amount of hydrated alumina powder and red phosphorus powder per 100 parts by weight is the following points A, B, C, D, E, F,
An epoxy resin composition characterized in that the composition lies within a range surrounded by connecting the points shown by G and H. However, points A, B, C, D, E, F, G, and H indicate the following compositions. [Table] [Table] 2 Epoxy resin for epoxy varnish consisting of 100 parts by weight of epoxy resin, acid anhydride, and reaction accelerator
Claim 1, characterized in that the amount of hydrated alumina powder and red phosphorus powder mixed per 100 parts by weight is within the range bounded by connecting the points D, E, and J below. The epoxy resin composition described. However, points D, E, and J indicate the following compositions. 【table】