JPS59191206A - Method of producing flyback transformer - 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 Application of the Invention] The present invention relates to a method of manufacturing a flyback transformer by performing insulation treatment using a polybutadiene-based thermosetting resin composition, and relates to a method of manufacturing a flyback transformer by performing insulation treatment using a polybutadiene thermosetting resin composition. The present invention relates to a method of manufacturing a flyback transformer that simultaneously insulates the transformer to significantly reduce the cost and improve the reliability of the product.

[Prior art]

Epoxy resin compositions are currently used as cast insulating materials for flyback transformers for color televisions.

This currently used epoxy resin composition has mechanical and electrical problems that make it difficult to integrate and insulate the components that make up the flyback transformer. The reality is that they are expensive.

A flyback transformer for a television receiver is composed of many parts, and these parts are individually insulated.

For example, a plasti with multiple partition walls, a primary coil wound in sections around a square, a secondary coil with one or more glass-molded diodes wired and wound in sections similar to the primary coil, and a secondary coil for focus voltage adjustment. resistance,
It consists of an epoxy resin molded capacitor, and parts made of case nuts, and is manufactured as a finished product by individually insulating these parts with cast resin.

When a flyback transformer is manufactured by integrating the above components and performing insulation treatment, the following problems occur.

In other words, since there is a large difference in the coefficient of thermal expansion of each of the above components, when the casting resin is cooled after being heated and cured, or when the temperature cycle that occurs when using a flyback transformer is applied, the temperature of each component changes. Complex stress is generated between the resin and the molded resin, causing cracks and peeling in the cured resin.

On the other hand, since high voltage is applied to each component of a flyback transformer, the cracks, cracks, and peeling described above may occur.
This will cause corona discharge, leading to dielectric breakdown of the flyback transformer.

In consideration of the problem of cracks and peeling of the hardened resin due to complex stress, as well as the problems of dielectric breakdown caused by this, thermosetting epoxy resin, thermosetting epoxy resin, Unsaturated polyester resin, silicone rubber, etc. were used.

In other words, these resins have excellent mechanical and insulation properties, and although silicone rubber is a completely different rubber elastic body from these resins, it has excellent flame retardant and dielectric properties. It was utilized and used.

However, although epoxy resins and unsaturated polyester resins have excellent mechanical properties, they are weak against thermal shock, and cracks often occur due to sudden temperature changes, reducing product reliability. There is a problem.

Furthermore, the resin contracts during heat curing and hardens with stress remaining inside, which promotes cracking or peeling when the component undergoes thermal expansion or temperature change.

This tendency is particularly strong in unsaturated polyester resins, and has become a major problem.

In order to solve these drawbacks or problems, it is often attempted to impart flexibility to resins.

However, imparting flexibility to the resin may lead to deterioration of the dielectric properties, which may be a fatal drawback as an insulating material, and is not practical. Also, silicone rubber is
Although it is a material with a low dielectric constant and dielectric loss tangent and has excellent flexibility, its uses are limited due to its high cost and high moisture permeability.

In addition to the above-mentioned insulating materials, there are urethane-based insulating materials that use polyester, polyether, or castor oil-based materials as the polyol component, but they have poor water resistance and dielectric properties.
Although it has flame retardant properties, it is not used for casting or resin casting in high-voltage coils, flyback transformers for televisions, etc.

There are also products that use 1,4-polybutadiene-based materials as the polyol component, but these are superior to the above-mentioned urethane-based materials in terms of water resistance and dielectric properties. Due to the short usage time, there is a technical problem in that the impregnation of the resin between the coils is insufficient, resulting in dielectric breakdown of the flyback transformer.

Note that some polyisocyanates have low reactivity, but these have low safety, long curing times,
In addition, masked incyanate, which has low reactivity and high safety,
In addition to the high curing temperature, the mask material separates during curing to generate voids, and the mask material remaining in the cured product causes deterioration of dielectric properties.

As mentioned above, there is no currently known cast insulating material that simultaneously satisfies both the mechanical and electrical properties required for flyback transformers. The reality is that it is not possible to perform insulation treatment that integrates the transformer.

[Purpose of the Invention] The inventors have developed a product that satisfies both the mechanical and electrical properties required for a flyback transformer, integrates and insulates the flyback transformer, and improves product reliability and reduces cost. As a result of considering both aspects of value, we have developed an excellent cast insulating material that satisfies all requirements.

That is, the object of the present invention is to provide a cured resin composition with good crack resistance, good adhesion between the cured resin and each component of a flyback transformer, and good dielectric properties and flame retardancy of the cured resin. Furthermore, we obtained a polybutadiene-based thermosetting resin composition that has moderately low reactivity, a long pot life, good workability, and good impregnation between coils, and with this resin composition, we integrated a flyback transformer. The present invention aims to provide a manufacturing method that simultaneously improves the reliability and product value of a flyback transformer by insulating the flyback transformer.

[Summary of the invention]

That is, the present invention provides liquid 1,4-borobutadiene having a molecular weight of 500 to 10,000 and having hydroxyl groups at both ends of the molecule.
0.5 to 6.0 equivalents of incyanate represented by IHI are blended with 100 parts of En homopolymer per 1 equivalent of active hydrogen in the polymer component, and 20 to 90 parts by weight of aroma oil is added to this. part, hydrated alumina powder 60
A resin composition is prepared by blending 160 parts by weight of 160 parts by weight with 10 to 50 parts by weight of red phosphorus powder, and using this resin composition, a flyback transformer is integrated and insulated to manufacture a flyback transformer. It is characterized by

[Embodiments of the invention]

An embodiment of the present invention will be described in detail below.

First, a thermosetting resin composition that can be used in this example will be described. Liquid 1,4-polybutadiene homopolymer having hydroxyl groups at both ends of the molecule has a molecular weight of 500 to 1.
0,000 is valid.

For example, butadiene monopolymer polyols commercially available from Idemitsu Petrochemical Co., Ltd. under the trade names R-45ET and R-45M can be used.

From the viewpoint of property saturation, it is desirable that the incyanate be in a proportion of 0.5 to 3.0 equivalents per equivalent of active hydrogen in the liquid 1,4-polybutadiene homopolymer component having a hydroxyl group at the end of the chemical formula shown below. .

The chemical formula is as follows.

Aromatic oils are effective as viscosity reducing agents, and commercially available products include AH-16 and AC manufactured by Idemitsu Petrochemical Co., Ltd.
-460, AC-12, etc.

The blending amount is the above liquid 1.4 having hydroxyl groups at both ends of the molecule.
-2 for 100 parts by weight of polybutadiene homopolymer
0 to 90 parts by weight is good; if it is less than 20 parts by weight, the effect as a viscosity reducing agent will be reduced, and the impregnating property between coils will become opaque, and if it is more than 90 parts by weight, crack resistance, adhesive properties, mechanical properties, flame retardancy, and dielectric properties are significantly reduced.

As the hydrated alumina powder, those represented by the chemical formulas M2C), .6B, and 0 may be used, and commercially available products can be used satisfactorily. This material has flame retardant properties.

The blending amount is the above liquid 1.4 having hydroxyl groups at both ends of the molecule.
- 3 parts per 100 parts by weight of polybutadiene homopolymer
0 to 160 parts by weight is good. If it is less than 30 parts by weight, the flame retardant effect will decrease, and if it is more than 160 parts by weight, the dielectric constant and dielectric loss tangent will deteriorate, and the coil impregnation property and workability will increase due to increased viscosity. This results in a decrease in

The average particle size of this hydrated alumina powder is preferably 2 to 35 μm.

Red phosphorus powder is effective in providing flame retardancy, and particularly when used in combination with the above-mentioned hydrated alumina, it exhibits excellent flame retardancy due to the synergistic effect of both.

By blending this red phosphorus powder, the blended amount of hydrated alumina can be reduced to a predetermined amount, making it possible to impart flame retardancy without deteriorating dielectric constant or dielectric voltage contact.

The amount to be blended is preferably 10 to 50 parts by weight per 100 parts by weight of the liquid 1,4-polybutadiene homopolymer having hydroxyl groups at both ends of the molecule, and if it is less than 10 parts by weight, the flame retardant effect is Even if it exceeds 50 parts by weight, the flame retardant effect remains unchanged, the resin becomes thicker, the coil impregnating property decreases, and the resin becomes more expensive.

The average particle size of the red phosphorus powder is preferably 1 to 150 μm.

It was also found that those surface treated with phenol resin etc. are even more effective.

In addition, other inorganic fillers, silane coupling agents, antifoaming agents, colorants, deterioration inhibitors, and the like may be added to improve properties or as necessary.

Next, a method for measuring the properties of the thermosetting resin composition described above will be explained.

(1) Regarding the crack resistance of cured resin products, a test piece (diameter 22 mm, thickness 7 mm) with a mild steel C-shaped washer embedded in the resin composition was prepared with an upper temperature constant of 100°C and a lower limit temperature of 40°C. A heat shock test is performed while lowering the temperature by 10℃ every cycle (each temperature is held for 2 hours) from ℃, and the temperature at which cracks occur in the test piece is determined for 10 test pieces, and the average value is is taken as the crack initiation temperature, and is shown as the crack resistance.

In other words, the crack resistance of the resin is better at lower temperatures.

(2) Regarding adhesion, aluminum rod (diameter 11.3 wm, adhesive area 1 cr)
i) sandwiched a 12 m x 12
A resin composition with an adhesive layer of about 50 μm was attached between the T plate and the resin composition, and the resin composition was heated and cured to obtain a test piece.

This test piece was subjected to a tensile test, and its fracture surface was observed, and it was confirmed that each test piece broke and peeled between the resin and the pBT plate. The measured value was the average value of 10 measured values at 25°C. (3) Regarding water resistance, according to JISK6911, 6 samples were measured at 23°C,
The water absorption rate (%) of the cured resin product was measured after 24 hours, and the average value was used as a measure of water resistance. Resins with lower water absorption have excellent water resistance.

(4) Dielectric properties were determined at 90° C. and 10 KHz according to JISK 6911. Of the six samples, those with a dielectric constant of 4 or less and a dielectric voltage contact of 2% or less are marked with an "○" mark, and the others are marked with an "x" mark.

(5) Regarding pot life, the time required for the viscosity of the resin to double at 40°C is shown as the average value of three samples.

(6) Mechanical properties at high temperatures were determined at 90°C according to JISK 6301. For 5 samples, the tensile strength was 50 yen or more and the elongation was 20.
Items with a percentage of 0% or higher are indicated with a “○” mark, and other items are marked with a “○” mark.
Marked with “×”.

(7) Flame retardancy was determined using a 1/16 inch thick test piece according to the UL 94 standard. Items that pass ULq4V-0 are designated as “V-
0" symbol, and those that failed were designated as "combustible."

(8) Regarding impregnability, to test the impregnation ability of resin between coil windings, cut the coil winding part of a flyback transformer that has been cast and cured with resin, and observe the cut surface with a microscope at approximately 50x magnification. Then, the ratio of the resin impregnated between the coils to the area between the coils was investigated. A score of 95% or higher was considered a pass. All resin curing conditions are 60℃/6 hours +
The temperature was 100°C/2 hours.

Example 1゜In the resin compositions shown in Examples A1 to 9 and Comparative Examples A1 to 8 in Table 1, the degree of crack generation, adhesion, water absorption rate, electric properties, pot life, and mechanical properties at high temperatures were evaluated. The characteristics, flame retardancy, and impregnability into a flyback transformer were measured according to the above measurement methods, and the results shown in Table 2 were obtained.

The following became clear from Table 2.

(1) Regarding the temperature at which cracks occur, casting resin for flyback transformers has a temperature at which cracks occur at 150°C.
Cannot be used unless the temperature is below ℃.

In Examples A1 to A9 in the table, the temperature was lower than 170°C, and in the comparative examples, the temperature was also lower than 170°C, except for A4, and satisfactory results in terms of crack resistance were obtained.

Comparative example 4 has a higher blending ratio of AC-12 (aroma oil) at 100 parts by weight than the others, and the crack temperature is -30°C, and Example 45 has a higher blending ratio of AC-12. is 90 parts by weight, but the crack temperature is -70°C or less.

From this, the blending ratio of aroma oil is 90 to 100.
The strength suddenly decreases at the weight part, and ltmllllH59
-191206 (5) It was confirmed that the crack resistance was drastically deteriorated.

In addition, Example M 4 (aroma oil blending ratio 20'X parts by weight) and Comparative Example A3 (aroma oil blending ratio 10 parts by weight),
It was confirmed that cracking temperatures of both samples were below 170° C., and those containing a small aroma oil blending ratio had no significant effect on cracking properties.

(2) Regarding adhesion, Examples 1 to 9 in the table were higher than 60Yi, and all comparative examples except /I64 were higher than 60Yi, and it was confirmed that the adhesiveness was sufficiently satisfactory.

In this case as well, Example 5 (aromatic oil blending ratio 90 parts by weight) and Comparative Example 4 (aromatic oil blending ratio 10 parts by weight)
0 parts by weight), it is understood that the adhesiveness changes rapidly when the aroma oil blending ratio is 90 to 100 parts by weight, and 90 parts by weight is the upper limit. Furthermore, from Example 4 and Comparative Example 3, it was confirmed that even if the blending ratio of aroma oil is small, it is not affected much. 4(3) Regarding the water absorption rate, it was confirmed that the water absorption rate was lower than 0.5% in both Examples and Comparative Examples.

(4) Regarding dielectric properties of resin, Examples 41 to 9
I was satisfied overall, and I was also satisfied with the comparative examples except for Ya4 and A6. Regarding the dielectric properties, it was confirmed that when the aroma oil exceeds 90 parts by weight, the dielectric properties are affected. Further, regarding the blending ratio of hydrated alumina powder, Example A7 (1
60 parts by weight) and Comparative Example A6 (180 parts by weight), it is found that the upper limit is between 160 and 180 parts by weight, and it has been confirmed that there is no effect at least at 160 parts. . Also, the blending ratio of hydrated alumina powder is 3aX
From Example 46, which is part t, it was confirmed that K, which has a small blending ratio, does not have much influence.

5) Concerning pot life: When using resin for flyback transformers, it is necessary to impregnate the space between the coil windings with resin.

For this purpose, it is important that the reactivity of the resin is appropriately low. Using pot life as a guideline, it can be said that root skin responsiveness is low if this time is long. Judging from past experience, the pot life should exceed at least 5 hours at 40°C.

Comparative Examples 41 and /I6 not using incyanate of the present invention
Both Examples 41 to 9 and Comparative Example using the incyanate of the present invention had a pot life of 5 hours or more, and it was confirmed that they had excellent impregnation properties.

(6) Regarding mechanical properties at high temperatures, all of the other Comparative Examples and Examples except Comparative Example/I64 in which the amount of AC-12 (aromatic oil) was excessive were good. In this case as well, it can be seen that the upper limit of the blending ratio of the aroma oil is between 90 and 100 parts by weight.

(7) Regarding flame retardancy, flame retardancy is an important characteristic for flyback transformer 9, and only resins that pass UL94V-0 can be used.

Comparative Example 44, which contained an excessive amount of 4C-12, Comparative Example 5, which contained a small amount of hydrated alumina powder, and Comparative Example 7, which contained a small amount of red phosphorus, all failed in terms of flame retardancy. All of the comparative examples and examples except for comparative example 44.45/I67 satisfied flame retardancy.

(8) Regarding impregnating properties, Comparative Examples Mu 1 and 42 using incyanate other than the present invention
．． Comparative Example 6 with a small amount of AC-12 (aromatic oil) (10 parts by weight), hydrated alumina amount (18031
Both Comparative Example A6, which had an excessive amount of Et (parts by weight), and Comparative Side Flex 8, which had an excessive amount of red phosphorus (60 parts by weight), were insufficient.

However, all of the other comparative examples and examples other than the above-mentioned comparative example had good impregnation properties.

From the above measurement results, it was confirmed that Examples 41 to 9 were resin compositions that satisfied all the characteristics.

Example 2 As shown in the figure, it was confirmed that the crack resistance of the primary bobbin 2 and the secondary bobbin was rapidly deteriorated.

In addition, Example Ya 4 (aroma oil blending ratio: 20 parts by weight) and Comparative Example A3 (aroma oil blending ratio: 10 parts by weight) both have a crack temperature of -70°C or less, and have a small aroma oil blending ratio. It was confirmed that K did not have much effect on cracking properties.

(2) Regarding adhesion, the Examples and /161 to 9 in the table were higher than 60 summer, and the comparative examples were also higher than 60 summer, except for A4, and it was confirmed that they were fully satisfactory.

In this case, similarly, Example A5 (aromatic oil blending ratio 90 parts by weight) and Comparative Example A4 (aromatic oil blending ratio 10 parts by weight)
0 parts by weight), the adhesion was determined when the aroma oil blending ratio was 9o to io.

It is understood that there is a rapid change in parts by weight, with an upper limit of 90 parts by weight. Furthermore, it was confirmed from Example J164 and Comparative Example 3 that even if the blending ratio of aroma oil is small, it is not affected much.

(3) It was confirmed that the water absorption rate was lower than 0.5% in both Examples and Comparative Examples.

(4) Regarding dielectric properties of resin, Examples A1 to 9
were all satisfied, and the comparative examples were also satisfied except for 44 and A6. Regarding the dielectric properties, it was confirmed that if the amount of aroma oil exceeds 90 parts by weight, the dielectric properties are affected. Further, regarding the blending ratio of hydrated alumina powder, Example A7 (1
60 parts by weight and Comparative Example A6 (180 parts by weight), it is found that the upper limit is between 160 and 180 parts by weight, and it has been confirmed that there is no effect at least at 160 parts. . Also, the blending ratio of hydrated alumina powder is 3ag.
It was confirmed from Example A6, which is a part by weight, that K, which has a small blending ratio, does not have much effect.

(5) Regarding pot life: When using resin for flyback transformers, it is necessary to impregnate the space between the coil windings with resin.

For this purpose, the reactivity of the resin must be moderately low.
−・・・・・・Cast resin part 2・・・・−・・・・・・
Primary bobbin 3・・・・・・・・・Secondary bobbin 4・・・・・・
...Diode 5...Primary coil 6...-
...Secondary coil 7...Focus resistor 8...
・・・・・・Capacitor 9・・・・・・・・・・・・
Case

Claims (1)

[Claims] As a cast insulating resin composition for a flyback transformer, the chemical formula of the isocyanate is added to 100 parts by weight of a liquid 1,4-polybutadiene homopolymer having a molecular weight of 500 to 10,000 and having hydroxyl groups at both molecular ends. 0.5 to 6.0 equivalents are blended per equivalent of active hydrogen in the ingredients, and 20 to 90 parts by weight of aroma oil is added to this.
30 to 160 parts by weight of hydrated alumina powder, 10 parts by weight of red phosphorus powder
A method for manufacturing a flyback transformer, which comprises blending 50 parts by weight of the resin composition, and carrying out integrated insulation treatment using this resin composition.