JPH08298083A - Ferrite sheet for magnetic field correction of deflecting yoke - Google Patents

Abstract

PURPOSE: To provide a ferrite sheet for magnetic field correction with heat resistance, flame retardance, flexibility, no-drop in electric insulation even under high-humidity environment, and good molding capability by using ferrite powder- mixed resin having specified ingredients. CONSTITUTION: A ferrite sheet 2 for magnetic field correction is directly stuck on the surface of a winding 1 of a curved reflecting yoke A with an adhesive layer stacked on the back surface. Ingredient in ferrite powder-mixed resin of the sheet 2 are 10-60wt.% binder and 90-40wt.% soft ferrite. Ingredient in the binder is 40-100 pts.wt. the total amount of a flame retardant and an auxiliary flame retardant based on 100 pts.wt. of the binder, and ingredient in the resin is 50wt.% or more ethylene propylene rubber and 50wt.% or less butyl rubber. Even when the sheet is exposed under high temperature high humidity environment for a long time, generation of a metal salt caused by dissociation of chlorine from the resin is prevented, electric insulation is kept high, and sheet formation is made easy.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic field compensating ferrite sheet used for adjusting the magnetic field of a deflection yoke mounted on the neck portion of a cathode ray tube, and more specifically, heat resistance, flame retardancy, flexibility and formability. The present invention relates to a ferrite sheet for magnetic field correction of a deflection yoke, which is excellent not only in heat resistance but also in humidity resistance.

[0002]

2. Description of the Related Art A technique for attaching a magnetic field correcting ferrite sheet (hereinafter referred to as a ferrite sheet) to the winding surface of a deflection yoke mounted on a cathode ray tube used for a television, a CRT display or the like is known. The ferrite sheet is formed by molding a composition in which soft ferrite powder is dispersed and mixed in a binder into a sheet shape. As shown in FIG. 1, the ferrite sheet 2 has a curved deflection yoke A due to an adhesive layer laminated on the back surface thereof. It is used by directly attaching it to the surface of the winding 1. Vinyl chloride added with an appropriate amount of a plasticizer is most commonly used as a binder, and manganese zinc ferrite is most commonly used as a soft ferrite.

For such a ferrite sheet,
Heat resistance, flexibility and flame retardancy are important. The flexibility is necessary for keeping the curved shape along the curved deflection yoke surface for a long time, and the flame retardancy is necessary for preventing ignition. Heat resistance refers to the property of maintaining the necessary electrical insulation when used as a magnetic field correction ferrite sheet for a long time in a high temperature environment. Although the winding of the deflection yoke has an insulating layer on the surface, it is impossible to completely eliminate the pinhole from the insulating layer, so this long-term heat resistance is extremely important from the viewpoint of preventing dielectric breakdown, Specifically, it is required to constantly maintain the electric insulation of 10 ⁹ Ω / sq or more in surface resistance.

By the way, the heat generation amount of the deflection yoke tends to increase with the recent increase in size and high definition of television receivers, and further improvement in flame resistance and heat resistance is required. UL94V- which is a US official standard for flame retardancy
It is necessary to meet the standard of 0 as a minimum. Further, the heat resistance is required to constantly maintain a surface resistance value of 10 ⁹ Ω / sq. Conventionally, the environmental condition for maintaining this value is to withstand continuous use for 3000 hours under a use environment of 100 ° C. If you can do it, it was 120 recently.
It is required to withstand 3000 hours of continuous use under a temperature environment of ° C.

A conventional ferrite sheet using vinyl chloride to which an appropriate amount of a plasticizer is added as a binder has a surface resistance of about 10 ⁷ Ω / sq when continuously used for 3000 hours in a temperature environment of 120 ° C. The heat resistance cannot meet the above requirements. Under such circumstances, the applicant of the present application has proposed that the Japanese Patent Application No.
196192 and Japanese Patent Application No. 6-42219 have already been proposed. Japanese Patent Application No. 4-196192 discloses that the chlorine content as a binder is 3 because the dechlorination phenomenon is the cause of the decrease in heat resistance of the ferrite sheet using vinyl chloride.
It was proposed to use chlorosulphonated polyethylene limited to less than 0%. Chlorosulfonated polyethylene has excellent flexibility, and also has excellent heat resistance and self-extinguishing property, and even when exposed to a high temperature environment for a long time, the insulation hardly deteriorates. As a result of limiting the content to less than 30%, the dechlorination phenomenon when exposed to a high temperature environment for a long time is also slight, the generation of toxic chlorine gas is small, and the quality deterioration due to it is also small. I was able to get it.

However, this ferrite sheet still has some problems. When the surroundings are dry, it can prevent the generation of chlorine gas, prevent the deterioration of quality due to dechlorination, and have excellent electrical insulation properties.However, if the humidity is high or dew condensation causes water to adhere to the deflection yoke surface. In that case, a phenomenon occurs in which the electrical insulation is extremely deteriorated.
Further, in order to more effectively suppress the generation of chlorine gas and the dechlorination phenomenon in a high temperature environment, a small amount of magnesium oxide (MgO) having a chlorine capturing effect is usually added, but when magnesium oxide is added The phenomenon of deterioration of electric insulation under high humidity environment becomes more remarkable. Since the deflection yoke repeats a transition between a high temperature state and a low temperature state depending on whether the receiver is used or not, dew condensation on the surface of the deflection yoke cannot be avoided, and therefore the above problem is serious.

The present inventor endeavored to investigate the cause of this phenomenon,
It was found that the cause is the formation of metal salt and the dissociation phenomenon of this metal salt. That is, since ferrites such as manganese zinc ferrite, nickel zinc ferrite, and magnesium ferrite that are compounded in the ferrite sheet are metal oxides and have a chlorine-trapping effect, these ferrites combine with chlorine to have deliquescent properties. It is easy to generate the metal salt that it has. Since this metal salt has high hygroscopicity, moisture around the ferrite sheet is easily absorbed in the ferrite sheet, and after moisture absorption, the deliquescent property causes dissociation into metal ions and chlorine ions, and the electrical resistance of the ferrite sheet itself by ion conduction. Lower. Furthermore, the metal ions and chlorine ions not only stay inside the ferrite sheet but also elute into the water liquid condensed and attached to the periphery of the ferrite sheet, and the electric resistance of the water liquid is greatly reduced. Such a phenomenon also occurs with magnesium oxide (MgO) added for the purpose of suppressing generation of chlorine gas and dechlorination phenomenon. MgO that has captured chlorine is highly hygroscopic magnesium chloride (Mg
Cl), and this magnesium chloride absorbs ambient moisture and dissociates into magnesium ions and chlorine ions due to its deliquescent property, and the electrical resistance of the ferrite sheet itself is greatly reduced by ion conduction.

Japanese Patent Application No. 6-42219 was invented in order to solve such a problem, and has a chemical formula [Mg ₆ Al ₂ (OH) ₁₆ C having a chlorine capturing action on a binder resin.
O ₃ .4H ₂ O] and the chemical formula [Mg _4,5 Al ₂ (OH) ₁₃ C
O ₃ · 3.5H ₂ O] is added. Hydrotalcide has a special crystal structure and has the property of neutralizing the acid by the ion-exchange ability due to the crystal structure, and exhibits the ability to capture and inactivate chlorine ions in the synthetic resin. Compound. When an appropriate amount of hydrotalside is mixed in the binder resin, chlorine ions generated from the binder resin are replaced with CO ₃ in the hydrotalside structure and taken into the hydrotalside. Since the chlorine ions once captured do not desorb until the temperature rises above about 450 ° C., the chlorine ions are completely inactivated under the working temperature environment of the deflection yoke, and the chlorine ions are metal oxides as in the conventional case. It is possible to prevent the metal salt from being trapped by the ferrite and generating a metal salt. In addition, since the hydrotalcide that has captured chlorine ions does not have deliquescent properties, it does not absorb moisture in the atmosphere, and even when it comes into contact with the moisture adhering to the periphery of the ferrite sheet, it can dissociate into metal ions and chlorine ions It had the content of not being.

However, the following new problems have been clarified by the continuous research of the present inventor after the above application.
Although hydrotalside certainly has the above-mentioned characteristics, it has a limited chlorine-trapping ability, and therefore a large amount of hydrotalside needs to be blended to trap most of the chlorine generated from the binder resin. An increase in the blending ratio of hydrotalside means a decrease in the resin content ratio, which significantly deteriorates the moldability and makes it difficult to mold it into a sheet.
Further, hydrotalside is extremely expensive, and addition of a large amount of hydrotalside will lead to a significant increase in cost.

The present invention has been made in view of the above circumstances, and satisfies the basic characteristics concerning heat resistance, flame retardancy, and flexibility required for use as a ferrite sheet, and at the same time, in a high humidity environment. The purpose of the present invention is to provide a ferrite sheet for magnetic field correction, in which the electric insulating property does not deteriorate even when used, and the formability is good and the sheet processing is easy.

[0011]

In order to solve the above-mentioned problems, the present inventor returned to the origin and considered the phenomenon of the deterioration of the electric insulation property. As a result, the phenomenon of the deterioration of the electric insulation property caused by the generation of chlorine was found. The method of preventing chlorine by trapping chlorine ions is not an essential solution because even if it works on one side, the other side will always have an adverse effect.To solve this problem, chlorine is added to the structure. It was concluded that there was no choice but to select a binder resin not containing. And, as a result of continuing research to find a binder resin which does not contain chlorine in its structure, and which can satisfy all of heat resistance, flame retardancy, flexibility and moldability, and repeated examination of their compounding ratio, The present invention has been completed.

The present invention which has solved the above problems has the following contents. A ferrite sheet for magnetic field correction of a deflection yoke, which is obtained by molding a ferrite powder-containing resin, which is a mixture of a binder resin containing a flame retardant-promoting substance and soft ferrite, into a sheet, and the composition of components in the ferrite powder-containing resin is The binder resin is 10% by weight to 60% by weight, the soft ferrite is 90% by weight to 40% by weight, and the component composition in the binder resin is the total amount of the flame retardant and the flame retardant aid with respect to 100 parts by weight of the resin content. Is 40 parts by weight to 100 parts by weight, and the component composition in the resin component is 50% by weight or more of ethylene propylene rubber and 50% by weight or less of butyl rubber. Note that rubber is included in the concept of resin handled here.

A ferrite sheet according to claim 2, which is a compounding example in which the compounding ratio of each component is more specifically defined,
The composition of components in the ferrite powder blended resin is binder resin 1
2 to 45% by weight, soft ferrite 88 to 55% by weight, and the composition of components in the binder resin is 60 to 95 parts by weight of ethylene propylene rubber, 40 to butyl rubber.
5 parts by weight, 30 to 50 parts by weight of halogen-based flame retardant, 15 to 25 parts by weight of flame retardant aid, and 1 to 3 parts by weight of lubricant.

[0014]

[Effect] Since ethylene propylene rubber and butyl rubber do not contain chlorine at all, even if the ferrite sheet is exposed to a high temperature and high humidity environment for a long time, chlorine is not dissociated from the resin and a metal salt is not generated. Absent. Chlorine is contained in the flame retardant promoting substance, but due to the nature of the flame retardant promoting substance, chlorine cannot be dissociated at a temperature of about 120 ° C., and therefore, the generation of the metal salt causes an electric discharge. The phenomenon that the insulation is deteriorated does not occur.

[0015]

EXAMPLES Next, details of the present invention will be described based on examples. The magnetic field correction ferrite sheet of the present invention is a magnetic field correction ferrite sheet of a deflection yoke obtained by molding a ferrite powder-containing resin, which is a mixture of a binder containing a flame retardant promoting substance and soft ferrite, into a sheet shape,
The composition of the ferrite powder-containing resin is as follows: binder 10 wt% -60 wt%, soft ferrite 90 wt% -40
%, And the component composition in the binder is such that the total amount of the flame retardant and the flame retardant aid is 40 parts by weight to 100 parts by weight with respect to 100 parts by weight of the resin content, and the component composition in the resin component is Is 50% by weight or more of ethylene propylene and 50% by weight or less of butyl rubber. The more preferable composition of components in the ferrite powder-containing resin is 12 to 45% by weight of binder and 88 to 55% by weight of soft ferrite, and the composition of components in the binder is 60 to 95 parts by weight of ethylene propylene rubber, 40 to butyl rubber.
5 parts by weight, 30 to 50 parts by weight of halogen-based flame retardant, 15 to 25 parts by weight of flame retardant aid, and 1 to 3 parts by weight of lubricant.

The composition of components in the ferrite powder-containing resin is set to 90% by weight to 40% by weight of soft ferrite with respect to 10% by weight to 60% by weight of the binder. If the content of soft ferrite is less than 40% by weight, the minimum magnetic properties required for a magnetic field correction ferrite sheet cannot be obtained.
On the other hand, if it exceeds 90% by weight, it becomes impossible to form a sheet. Which value is specifically selected within the range of 90% by weight to 40% by weight is determined according to the required magnetic characteristics. Generally, the AC initial permeability (μ _iac ) at 1 KHz is adjusted to be 6 to 9,
In this range, the blending ratio of soft ferrite is about 15% by weight. As the soft ferrite, known ones such as manganese zinc ferrite, nickel zinc ferrite, and magnesium ferrite can be used as appropriate, but manganese zinc ferrite is preferably used because of its excellent electric insulation and magnetic properties.

The composition of the components in the binder is resin content 1
40 parts of the total amount of flame retardant and flame retardant aid with respect to 00 parts by weight
The amount is set to 100 parts by weight. Of flame retardant and flame retardant aid
If the compounding amount is less than 40 parts by weight, it is necessary for the ferrite sheet.
Must meet the UL94V-0 standard, which is the required flame retardancy.
I can't. On the other hand, on the amount of flame retardant and flame retardant auxiliary compounded
The limit is not specified technically, but flame retardance and
And flame retardant aids are about 10 times more expensive than resin
Therefore, due to cost constraints, the upper limit of the blending amount is specified.
Be done. 100 parts by weight is the upper limit as an industrially suitable value.
is there. Known flame retardants and flame retardant aids can be used.
Wear. Examples of flame retardants include brominated and chlorinated halogens.
Flame retardants can be used, specifically hexabromobenze
, Ethylene tetrabromide, chlorinated paraffin, etc. can be used
It For example, as a flame retardant aid used in combination with halogen-based flame retardants
If antimony trioxide (Sb ₂O₃) Can be used. Flame retardant
The ratio of the flame retardant and the flame retardant aid is also set as appropriate.
Add about 20 parts by weight of flame retardant aid to 40 parts by weight.
And can be cited as an example.

As the resin component, a mixture of ethylene propylene rubber (EPDM) and butyl rubber is used. Both ethylene propylene rubber and butyl rubber are resins containing no chlorine, and the use of these resins is the greatest feature of the present invention. The compounding ratio of ethylene propylene rubber in the resin component is set to 50% by weight or more, while butyl rubber is set to 50% by weight or less. The purpose of compounding the butyl rubber is to adjust flexibility, and if the compounding amount of the butyl rubber exceeds 50% by weight, the butyl rubber becomes too soft and shape retention becomes difficult, and it cannot be molded into a sheet. Alternatively, the butyl rubber may not be blended, and the total amount of the resin component may be composed only of ethylene propylene rubber. Since ethylene propylene rubber is a rubber and therefore has a certain degree of flexibility, the flexibility to the extent that it follows the deflection yoke can be sufficiently realized without compounding butyl rubber. However, if butyl rubber is not added, the softness required for calendar roll molding cannot be obtained, and sheet processing becomes difficult. On the premise of sheet processing by calender roll forming, butyl rubber needs to be compounded, and the preferable compounding amount is 30 parts by weight of butyl rubber to 70 parts by weight of ethylene propylene rubber. Needless to say, a small amount of lubricants, stabilizers and the like may be added to the ferrite powder-containing resin in addition to these.

Next, the results of tests conducted to confirm the effects of the present invention will be described. The ferrite powder-containing resin having the composition shown in Table 1 was processed into a sheet to obtain three kinds of ferrite sheets of Example, Comparative Example 1 and Comparative Example 2. The unit of numerical values in the recipe is parts by weight. Further, in the table, "the blending ratio of ferrite" indicates the blending ratio of soft ferrite in the total weight of the ferrite powder-containing resin. The processing conditions are as follows: Example and Comparative Example 1 were kneaded at 60 ° C. for 15 minutes, while Comparative Example 2 was kneaded at 160 ° C. for 15 minutes to prepare a resin containing ferrite powder, and a ferrite sheet having a thickness of 0.4 mm was calendered. Obtained by roll forming. Moldability was good in all cases. Moreover, all conformity tests of UL94V-0 passed. Next, heat resistance regarding electrical insulation characteristics,
A moisture resistance test was conducted. The electrical insulation characteristics were evaluated by surface resistance. The measurement procedure is as follows. After aging (drying) the ferrite sheet at a temperature of 140 ° C. for 48 hours,
The sample was left for 96 hours in a room in the environment of ° C and a humidity of 60 RH%, and measured at each stage of the initial state, immediately after aging, and after the room. The results are shown in Table 1.

[0020]

[Table 1]

As a result of the test, in Comparative Example 1 using chlorosulfonated polyethylene, the surface resistance after being left indoors is much lower than that immediately after aging, whereas the product of the present invention using ethylene propylene rubber is used. It was confirmed that the surface resistance did not decrease even after being left indoors. The product of the present invention shows excellent electrical insulation of 9 × 10 ¹² Ω / sq even after being left indoors in a high humidity environment, and is required for a magnetic field correction ferrite sheet used for a deflection yoke for a large, high-definition display. It was confirmed that the electric insulation property was sufficiently satisfied. On the other hand, adhesion of deliquescent magnesium chloride was observed on the surface of the ferrite sheet of Comparative Example 1 after being left indoors, and it was confirmed that this was involved in the deterioration of electrical insulation. Further, in Comparative Example 2 using vinyl chloride, although the surface resistance after being left indoors did not decrease as compared with immediately after aging, the surface resistance itself after aging was only about 5 × 10 ¹⁰ Ω / sq.
It was confirmed that there was concern about the ferrite sheet for magnetic field correction used for the deflection yoke for large-sized, high-definition displays.

[0022]

INDUSTRIAL APPLICABILITY The magnetic field correcting ferrite sheet of the present invention is a magnetic field correcting ferrite sheet obtained by sheet-processing a ferrite powder-containing resin comprising soft ferrite and a binder. The total amount of the flame retardant and the flame retardant auxiliary is 60 parts by weight to 100 parts by weight with respect to parts by weight, and the component composition in the resin component is 50% by weight or more of ethylene propylene rubber and 50% by weight or less of butyl rubber. Since chlorine is completely removed from the resin, chlorine does not dissociate from the resin to form a metal salt even when exposed to a high temperature and high humidity environment for a long time, and excellent electrical insulation is maintained. You can Further, the above ferrite powder-containing resin is easily processed into a sheet, and the ferrite sheet obtained by the sheet processing has sufficient flame retardancy and is also flexible enough to maintain the adhered state along the curved inner surface of the deflection yoke. Have As described above, the ferrite sheet for magnetic field correction of the present invention has flexibility, formability, flame retardancy, and also heat resistance and moisture resistance capable of assuring excellent electrical insulation properties, and makes it possible to increase the size and definition of a display. Accordingly, it is possible to provide a ferrite sheet suitable for use in a deflection yoke, which is expected to generate an increased amount of heat.

[Brief description of drawings]

FIG. 1 is a perspective view showing a state in which a magnetic field correction ferrite sheet is attached to the inner surface of a deflection yoke.

[Explanation of symbols]

 A Deflection yoke 1 Winding 2 Ferrite sheet

Claims (2)

[Claims] 1. A ferrite sheet for magnetic field correction of a deflection yoke, which is obtained by molding a ferrite powder-containing resin, which is a mixture of a binder containing a flame retardant promoting substance and soft ferrite, into a sheet shape. The component composition of the binder is 10% to 60% by weight of binder, and 90% to 40% of soft ferrite.
% By weight, and the composition of components in the binder is such that the total amount of the flame retardant and the flame retardant auxiliary is 40 parts by weight to 100 parts by weight with respect to 100 parts by weight of the resin content, and the components in the resin content are A ferrite sheet for magnetic field correction of a deflection yoke, the composition of which is 50% by weight or more of ethylene propylene rubber and 50% by weight or less of butyl rubber. 2. A ferrite sheet for magnetic field correction of a deflection yoke, which is obtained by molding a ferrite powder-containing resin, which is a mixture of a binder containing a flame retardant promoting substance and soft ferrite, into a sheet shape. The composition of components is binder 12-
45% by weight, 88 to 55% by weight of soft ferrite, and the composition of components in the binder is 60 to 95 parts by weight of ethylene propylene rubber, 40 to 5 parts by weight of butyl rubber, 30 to 50 parts by weight of halogen-based flame retardant, and difficult. Fuel aid 15
A ferrite sheet for magnetic field correction of a deflection yoke, which is ˜25 parts by weight and 1 to 3 parts by weight of a lubricant.