JPS62290718A - Epoxy resin composition and production of flyback transformer using same - Google Patents

Abstract

PURPOSE:To obtain the title composition excellent in heat resistance, moisture resistance, infiltrability and flame retardancy, by mixing a specified resin composition with an Al(OH)3 powder, a surface-treated red phosphorus powder and an acid anhydride curing agent. CONSTITUTION:A resin composition (a) is obtained by mixing 60-80pts.wt. epichlorohydrin bisphenol AD epoxy resin (i) of the formula (wherein n is 0-2) having an epoxy equivalent of 168-178 with 10-15pts.wt. diethylene glycol diglycidyl ether (ii) and 5-30pts.wt. 3,4-epoxycyclohexylmethyl 3,4- epoxycyclohexanecarboxylate. 100pts.wt. component (a) is mixed with 50-220pts. wt. Al(OH)3 powder (b) of an average particle diameter of 8-12mum and a content of particles of a particle diameter <=3mum (excluding 0mum) <=5wt%, 10-30pts.wt. red phosphorus powder (c) of an average particle diameter of 10-40mum and a content of particles of a particle diameter <=3mum (excluding 0mum) <=5wt% and an acid anhydride curing agent (d).

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an epoxy resin composition and a method for manufacturing a flyback transformer using the composition, and in particular, -Relates to a flame-retardant epoxy resin composition with good impregnation properties.

[Conventional technology]

The conventional flame retardant epoxy resin composition is epichlorohydrin bisphenol A type epoxy resin.

A method is known that consists of red phosphorus powder surface-treated with an acid anhydride curing agent, a curing accelerator, aluminum hydroxide powder, and a phenol resin (Japanese Patent Application Laid-Open No. 149940/1983).

[Problem that the invention seeks to solve]

In recent years, high-voltage electrical components such as flyback transformers (hereinafter referred to as FBTs) have been trending toward smaller sizes, higher temperature rise limits, and higher performance. Therefore, the epoxy resin composition used for insulating high-voltage electrical parts such as FBT has a glass transition temperature (Tg) of the cured product of 115°C or higher, and heat cycle resistance of 100°C for 2 hours and -50°C for 2 hours. It was necessary that no cracks or peeling of the resin occur from the area (3) even after 50 or more heat cycles.

In addition, from the viewpoint of increasing the reliability of insulation properties, demands for improving electrical properties after moisture absorption are becoming stricter. Therefore, it was necessary to improve the moisture-resistant electrical properties of cured epoxy resin products.

Furthermore, conventional epoxy resin compositions have a problem of poor impregnability into FBT and the like due to the aluminum hydroxide powder used as a retardant and the red phosphorus powder surface-treated with a phenol resin.

That is, in such an epoxy resin composition, as shown in FIG. 2, the aluminum hydroxide powder and the red phosphorus powder 10 are packed in a close-packed state in the upper layer of the secondary coil 6 wound around the secondary bobbin 3. The casting resin composition 1 may not penetrate to the deepest part of the coil and remain as a void, resulting in so-called poor impregnation, resulting in a resin-impregnated portion 6-1 and a non-resin-impregnated portion 6-2. There is a problem in that high-voltage parts obtained by curing under such conditions lead to dielectric breakdown.

The present inventors aim to obtain an epoxy resin composition that eliminates such conventional problems, and to manufacture a flyback transformer using the same.

[Means for solving problems]

In order to eliminate the above, the present inventors conducted extensive research and found that they combined alicyclic epoxy resin and epichlorohydrin bisphenol AD type epoxy resin as materials for the epoxy resin composition, and used aluminum hydroxide powder as a flame retardant.
We have also found that it is better to limit the average particle size of red phosphorus powder surface-treated with aluminum hydroxide powder and reduce the fine particle portion.

That is, 1 the present invention comprises: (1) 60 to 80 parts by weight of epichlorohydrin bisphenol AD type epoxy resin having the following chemical formula.

(However, n = 0 to 2. Epoxy equivalent = 168 to 178)
(2) 10 to 15 parts by weight of diethylene glycol diglycidyl ether, (3) 3.4-epoxycyclohexylmethyl-3°4
- 5 to 30 parts by weight of epoxycyclohexane lupoxylate, and a total of 10 parts of the above (1) + (2) + (3)
0 parts by weight, (4) 50 to 220 parts by weight of aluminum hydroxide powder containing 5% by weight or less of particles with an average particle size of 8 to 12 μm and an average particle size of 3 μm or less excluding 0 μm, (5) For example, the surface was treated with aluminum hydroxide.

Red phosphorus powder 10 with an average particle size of 10 to 40 μm and a content of particles with an average particle size of 3 μm or less, excluding 0 μm, of 5% by weight or less
~30 parts by weight, (6) an acid anhydride curing agent sufficient to cure the epoxy resin, (7) a curing accelerator if necessary.

This is accomplished by manufacturing a flyback transformer by insulating an epoxy resin composition and using the same.

The amount of the epichlorohydrin/bisphenol AD type epoxy resin (1) used in the present invention is preferably 60 to 80 parts by weight; if it is less than 60 parts by weight, the heat cycle resistance of the cured resin will decrease; If the amount is too large, the glass transition temperature (Tg) will be lower than 115° C. and the viscosity of the resin composition will be high, which is not desirable in terms of impregnability.

The amount of the reactive diluent diethylene glycol diglycidyl ether in (2) above is preferably 10 to 15 parts by weight;
If it is less than 0 parts by weight, the dilution effect will be small and the viscosity of the resin composition will increase, resulting in poor impregnability. If it is more than 15 parts by weight, the Tg of the cured resin will be lower than 115° C., which is not desirable.

The blending amount of the alicyclic epoxy resin in (3) above is preferably 5 to 30 parts by weight; if it is less than 5 parts by weight, the Tg of the cured resin will be lower than 115°C, and if it is more than 30 parts by weight, the heat cycle resistance will be reduced. decreases, which is undesirable.

Next, flame retardants will be described.

The aluminum hydroxide powder described in Item 1 (4) is preferably one having an average particle size of 8 to 12 μm and a content of particles with an average particle size of 3 μm or less excluding 0 μm of 5% by weight or less. When the average particle size is smaller than 8 μm, or when the content of particles with a particle size of 3 μm or less excluding 0 μm is more than 5% by weight, the impregnating property is significantly reduced and the composition is impractical. Furthermore, if the average particle size is larger than 12 μm, precipitation of aluminum hydroxide powder will occur significantly, and the properties of the cured resin will deteriorate.
For example, cracks or peeling from high-voltage components occur, and high-voltage components such as FBTs cause dielectric breakdown. In addition, the blending amount of aluminum hydroxide powder is preferably 50 to 220 parts by weight based on the total of 100 parts by weight of (1), (2), and (3) above, and if it is less than 50 parts by weight, the cured resin product may The flammability becomes insufficient, and if it exceeds 220 parts by weight, the viscosity of the resin composition increases significantly and impregnating into the coil becomes insufficient, and the resulting high-voltage parts are poor in practical use.

Furthermore, red phosphorus powder, which is a flame retardant that increases the flame retardant effect in combination with the above-mentioned aluminum hydroxide, will be described. Red phosphorus powder is surface-treated by depositing and coating aluminum hydroxide on its surface in order to increase moisture resistance, and commercially available products include Hishigart CP-A15 manufactured by Nippon Kagaku Kogyo KK. ), and in order to further improve the impregnating property, it is preferable to control the particle size as shown below.

In other words, in the red phosphorus powder that has been surface-treated as described above,
A material having an average particle size of 10 to 40 μm and containing 5% by weight or less of particles having a particle size of 3 μm or less excluding 0 μm is good in terms of moisture resistance and impregnability. Red phosphorus powder coexists with a large amount of aluminum hydroxide powder and is mixed and dispersed in the resin. When the average particle size is smaller than 10 μm, or when the content of small particles of 3 μm or less excluding 0 μm is more than 5% by weight, the impregnating property is significantly reduced and it is impractical.

moreover.

If the average particle size is larger than 40 μm, the red phosphorus powder will significantly settle and the properties of the cured resin will deteriorate, resulting in cracks and peeling from high-voltage parts, and high-voltage parts such as FBT may suffer dielectric breakdown. The amount of red phosphorus powder is as above (
The ratio of 10 to 30 parts by weight is good for the total of 100 parts by weight of 1) + (2) + (3). If it is less than 10 parts by weight, the flame retardancy of the cured resin will be insufficient, so 30 parts by weight If the amount is larger than this, the viscosity of the resin composition increases and impregnation into the coil becomes insufficient, resulting in poor practicality.

As the curing agent, an acid anhydride type is most suitable, and one that is liquid at room temperature is used. Generally, imidazole compounds and tertiary amine compounds can be used as reaction accelerators when acid anhydride curing agents are used.

In addition, the epoxy resin composition of the present invention may include known diluents, fillers, extenders, dyes, plasticizers, antifoaming agents,
A thixotropic agent or the like may be added as necessary.

[Effect]

Epichlorohydrin bisphenol AD type epoxy resin has a low viscosity and works effectively for impregnating the coil with the resin composition.

3.4-Epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate (alicyclic epoxy resin) is effective in improving the heat resistance of cured resin products.

Red phosphorus, a flame retardant, improves the electrical properties of cured resins blended with it after moisture absorption by surface-treating it with aluminum hydroxide.

Also, the flame retardants red phosphorus and aluminum hydroxide.

Improves impregnability by reducing particulate content.

〔Example〕

Next, examples of the present invention will be shown.

First, the materials used are shown below. Table 1 shows the resin component materials.

Table 1 *) Contains 1% by weight of curing accelerator 2 E l-1, M Z -CN (manufactured by Shikoku Kasei KK).

Further, the types of aluminum hydroxide powder are as shown in Table 2, and the types of red phosphorus powder are as shown in Table 3.

Table 2 Table 3 Phantom The case where the surface of the red phosphorus powder was treated by precipitation coating with aluminum hydroxide was defined as "Yes", and the case where no precipitation coating was applied was defined as "No" 6. Curing of the resin composition The conditions were 100° C. for 5 hours. The method for measuring the properties of the cured resin is described below.

1) Glass transition temperature (Tg): Differential scanning calorimeter (DS
C).

2) Model impregnation length: Average particle size 80μ in advance in a test tube
m of glass beads were placed, the resin composition was injected under vacuum at 10 ++ a Hg, cured under the above conditions, and the length of the impregnated layer in which the resin composition penetrated into the glass beads layer was measured. I did it.

3) Actual machine impregnation rate: As shown in Figure 1, the primary bobbin 2.2
Next bobbin 3. Diode 4, primary coil 5. secondary coil 6, focus resistor 7. Capacitor 8. Resin composition 1 was injected under vacuum at 10 mm Hg into an FBT made of case 9, and the resin-cast FBT was cut by heating and curing at 100° C. for 5 hours.

The cross section of the coil was observed under a microscope (approximately 80 times magnification) in the direction shown in FIG. For each slit, determine the ratio (%) of the area impregnated with the resin composition to the area between the coils,
The average value of each slit was taken as the impregnation rate. Those with a rating of 95% or more have good operating characteristics.

4) Flame retardancy: The flame retardancy of the cured resin material complied with UL standards. The test piece is L27nn x 12.7mm x 1.
A 6 m rectangular parallelepiped was used.

The flame retardancy of the actual FBT was determined according to the molding method. UL9/IV
If it is equivalent to −0 and passes the molding method, “○”, otherwise “×”
”.

5) Flame retardant (aluminum hydroxide powder and red phosphorus powder)
Sedimentation property: A transparent portion 11 as shown in FIG. 3 is generated, and the larger the sedimentation property is, the longer the length between the top and bottom of the transparent portion becomes, and the heat cycle resistance deteriorates, making it impractical.

6) Moisture resistance: Cured resin board at 60°C, 295%RH
Leave it for 1000 hours in the atmosphere of JIS K69
11, the ratio:A electric constant, dielectric loss tangent, and water absorption were determined at 25° C. and 10KI-rz. The relative dielectric constant is 4.5 or less,
In addition, when the dielectric loss tangent was 2.5% or less and the water absorption rate was 1% or less, it was passed as "O", and otherwise it was judged as "X".

7) Heat cycle resistance: 100
After performing 30 heat cycles of 2 hours at -50°C for 2 hours, the operating characteristics were examined to check its practicality.

8) Overall judgment: Those that satisfy all of the above characteristics are marked “○”
, those having even one insufficient characteristic were marked "×".

The above characteristics were determined using resin compositions having the weight blending ratios shown in Table 4. The properties of the obtained cured product are shown in Table 5.

(Left below) Tables 4 and 5 will be compared and discussed. That is, in Table 4, resin compositions Nα1 to Nα22 show examples of the present invention, and Nα23 to Nα48 show comparative examples, respectively.

In Comparative Examples &23 to 48, &23, in which the blending amount of R-710 is less than the inventive range, and N (128, in which the blending amount of E RL4221 is higher than the inventive range, both have poor heat cycle resistance and cracks occur. It was unsatisfactory. Comparative example & 2 in which the amount of R-710 blended was higher than the range of the present invention
No. 4 had low 'rg and poor impregnating properties.

Comparative Example Fish 25, which contained a smaller amount of Epolite 100E than the range of the present invention, had poor impregnating properties, and Fish 26, which contained a larger amount of Epolite 100E, had a low Tg and was unsatisfactory. Na21, in which the amount of E RL4221 contained was less than the range of the present invention, had a low Tg and was unsatisfactory.

Among the comparative examples Nα29 to 32 using aluminum hydroxide powder with a particle size range other than the present invention, it was still 29.31°3.
Sample No. 2 had poor impregnating properties, and Na30, which had a large average particle size, caused large sedimentation, and both were unsatisfactory in practical terms.

Further, even if aluminum hydroxide powder having a particle size within the range of the present invention is used, Comparative Example Nα33, which has a small amount blended, has insufficient flame retardancy, and Comparative Example Nci34, which has a large blend amount, has poor impregnation properties.

Next, comparative examples Nn35 to 47 of resin compositions using red phosphorus powder outside the range of the present invention will be described.

Comparative example Nα35 using red phosphorus powder without surface treatment
No. 39 has poor moisture resistance.

Comparative examples Nα40 to Nα4 using surface-treated red phosphorus powder
No. 7 has good moisture resistance. However, comparative example Nα4 using red phosphorus powder with a smaller average particle size than the range of the present invention
0, Comparative Examples Nα42 to Nα45 in which the content of particles with a particle size of 3 μm or less is higher than the range of the present invention, and Comparative Example N1147 in which the content of the red phosphorus powder of the present invention is also large, both have poor impregnation properties.

Comparative Example Nα41, which was surface-treated but had an average particle diameter larger than the range of the present invention, caused too much sedimentation and could not be put to practical use. Furthermore, Comparative Example NQ46, which uses the red phosphorus powder of the present invention but has a small amount blended, has insufficient flame retardancy.

Furthermore, Comparative Example 48 using EP8L5 had a low Tg and was unsatisfactory.

All of the FBTs manufactured using the resin compositions of Comparative Examples Na23 to Na23 to Na248 were unusable due to dielectric breakdown and combustion during checks of operating characteristics, life characteristics, flame retardance, and the like.

On the other hand, all of the resin compositions of Examples Ha 1 to 22 of the present invention satisfy the above characteristics.

All FBTs manufactured using these materials satisfied operating characteristics, life characteristics, N flammability, etc., and were highly reliable.

〔Effect of the invention〕

As described above, the epoxy resin composition according to the present invention has high heat resistance (Tg
), aluminum hydroxide powder with a suitable particle size and particle size distribution, and red phosphorus powder, which has undergone appropriate surface treatment and has an appropriate particle size and particle size distribution, are combined in appropriate amounts. It has excellent impregnation properties between the coils of a back transformer, and also has excellent dielectric properties when absorbing moisture.

Therefore, the flyback transformer obtained using this material has excellent operating characteristics such as withstand voltage characteristics and dielectric characteristics.

It has excellent life characteristics when absorbing moisture, has sufficient flame retardancy, and can be made highly reliable, so it has great industrial value.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a flyback transformer (FBT), FIG. 2 is a view of one slit portion of a coil cross-section showing an impregnated state, and FIG. 3 is a cross-sectional view of a coil showing sedimentation. 1... Casting resin composition, 2... Primary bobbin, 3...
・Secondary bobbin, 4...diode, 5...primary coil, 6...secondary coil, 7...focus resistor, 8
... Capacitor, 9 ... Case, 10 ... Aluminum hydroxide powder and red phosphorus powder, 11 ... Transparent part.

Claims (1)

[Claims] 1. 60 to 80 parts by weight of epichlorohydrin bisphenol AD type epoxy resin represented by the following chemical formula, ▲There are numerical formulas, chemical formulas, tables, etc.▼ (However, in the chemical formula, n = 0 to 2, epoxy equivalent =168～
178) Diethylene glycol diglycidyl ether 10-15
parts by weight, 5 to 3 parts by weight of 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, and an average particle size of 8 to 12 μm, excluding 0 μm, of 3 μm or less Contains 50 to 220 parts by weight of aluminum hydroxide powder with a particle size content of 5% by weight or less, and surface-treated particles with an average particle size of 10 to 40 pm, excluding 0 μm, and an average particle size of 3 μm or less Red phosphorus powder in an amount of 5% by weight or less 10-30
% by weight, and an acid anhydride curing agent sufficient to cure the composition blended in the above ratio. 2. 60 to 80 parts by weight of epichlorohydrin bisphenol AD type epoxy resin shown by the chemical formula below, ▲ There are numerical formulas, chemical formulas, tables, etc. ▼ (However, in the chemical formula, n = 0 to 2, epoxy equivalent = 168 to
178) Diethylene glycol diglycidyl ether 10-15
parts by weight, 5 to 30 parts by weight of 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, and an average particle size of 8 to 12 μm, excluding 0 μm, of 3 μm or less Contains 50 to 220 parts by weight of aluminum hydroxide powder containing 5% by weight or less of particles with a particle size, and surface-treated particles with an average particle size of 10 to 40 μm, excluding 0 μm, and an average particle size of 3 μm or less Red phosphorus powder in an amount of 5% by weight or less 10-30
% by weight and an acid anhydride curing agent sufficient to cure the composition in the above-mentioned proportions.