JPH07254378A - Ferrite sheet for correcting magnetic field of deflection yoke - Google Patents

Abstract

PURPOSE:To prevent deterioration of an electric insulating property even if water exists on a surface so as to enhance moisture resistance, water resistance, flexibility, and heat resistance by adding a predetermined quantity of hydrotalcite into a binder resin. CONSTITUTION:A plasticizer, a lubricant and a softener are added into a binder resin including mainly chlorosulfonated polyethylene including 30-wt.% or less of chlorine. Hydrotalcite is added into the resultant composition, followed by dispersingly blending soft ferrite powder, thus obtaining a sheet member 1a of a ferrite sheet 1 for correcting a magnetic field. 3-15 parts by weight of hydrotalcite is included into 100 parts by weight of the binder resin. Consequently, an electric insulative property cannot be reduced or an electric insulative property of water adhering to the surroundings due to moisture condensation cannot be reduced even if the sheet 1 is being used under the ambient of high moisture. As a result, it is possible to enhance moisture resistance, water resistance, flexibility, and heat resistance for a long period.

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. More specifically, it is excellent in heat resistance and also resistant to moisture and water. The present invention relates to an excellent ferrite sheet for magnetic field correction of a deflection yoke.

[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 synthetic resin binder into a sheet shape, and a winding of the deflection yoke a curved as shown in FIG. 4 by an adhesive layer laminated on the back surface thereof. b Used by directly pasting on the surface.

For such a ferrite sheet,
Electrical insulation, flexibility and heat resistance are extremely important. Although each winding of the deflection yoke has an insulating layer formed on the surface, it is impossible to completely eliminate the pinholes from the insulating layer, so the ferrite sheet directly attached to the winding surface has no electrical insulation. Required. In addition, flexibility is required to keep the curved shape along the curved deflection yoke surface for a long time, and heat resistance is the amount of heat generated by the deflection yoke due to the large size and high definition of the television receiver. It is necessary to cope with the increasing tendency.

In order to meet such demands, the present applicant has filed Japanese Patent Application No. 4-196192, and discloses a ferrite sheet using chlorosulfonated polyethylene having a chlorine content of less than 30% as a binder resin. I have already proposed. Chlorosulfonated polyethylene has excellent flexibility, and also has excellent heat resistance and self-extinguishing properties.
Furthermore, it can be said that the above requirements are almost satisfied because the insulation hardly deteriorates even when exposed to a high temperature environment for a long time. In this application, as a result of limiting the chlorine 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 chlorine gas which is a toxic gas is small, and the quality deterioration accompanying it is also small. Although a small ferrite sheet was obtained, a small amount of magnesium oxide (MgO) having a chlorine-trapping effect has recently been added to the binder resin for the purpose of further suppressing the generation of chlorine gas.

[0005]

The addition of magnesium oxide almost eliminates the generation of chlorine gas even when exposed to a high temperature environment for a long time, and the quality deterioration due to dechlorination is also eliminated. The characteristics are fully exerted when the ambient environment is dry, but when the humidity is high or when the moisture adheres to the deflection yoke surface due to dew condensation, the insulation between the windings deteriorates significantly. The new problem of doing has emerged. Condensation on the surface of the deflection yoke is unavoidable because the deflection yoke repeatedly transitions between a high temperature state and a low temperature state depending on whether the image receiver is used or not, and therefore the above problem is serious.

As a result of efforts to investigate the cause of this phenomenon, the present inventor has found the following fact. That is, Mg that has captured chlorine
O becomes magnesium chloride (MgCl), but since magnesium chloride has a high hygroscopicity, it easily absorbs moisture around the ferrite sheet into the ferrite sheet, and after moisture absorption, it dissociates into magnesium ions and chlorine ions due to its deliquescent property. The electric resistance of the ferrite sheet itself is reduced by ion conduction. Furthermore, it was found that magnesium ions and chlorine ions not only stay inside the ferrite sheet but also elute into the water solution that is condensed and attached around the ferrite sheet, and the electrical resistance of the water solution is significantly reduced. Further, ferrites such as manganese zinc ferrite, nickel zinc ferrite, magnesium ferrite, etc., which are mixed in the ferrite sheet, are also the above-mentioned Mg
Since it is a metal oxide similar to O and has a chlorine scavenging effect, these ferrites also combine with chlorine to form a metal salt having deliquescent property, and when this generated metal salt absorbs water, it is still a metal. It was also found that the dissociation into ions and chlorine ions causes the electrical resistance of the ferrite sheet itself to be reduced in addition to the behavior of MgO and the electrical resistance of water liquid adhering to the periphery to be further reduced. It was

Further studies show that such a phenomenon is not limited to the case of using chlorosulfonated polyethylene as the binder resin, but the occurrence of the phenomenon is mild when the binder resin containing other halogen group element is used. However, it was confirmed that it occurred similarly. For example,
When vinyl chloride is used, ferrite, which is a metal oxide, captures chlorine in vinyl chloride to form a deliquescent metal salt, and when this metal salt is exposed to moisture, the same problems as above occur. To do. In addition, even if the halogen group element is not contained in the main resin in the binder resin, if the flame retardant is added to the binder resin, the halogen group element and the ferrite in the flame retardant are added. And are combined to form a metal salt, which causes the same problem as described above, although slightly. The root cause of these phenomena is that halogen group elements such as fluorine, chlorine and bromine have the property of easily reacting with metal elements to form metal salts.
The metal salt thus produced has a deliquescent property and tends to dissociate into metal ions and halogen ions due to water absorption.

For the ferrite sheet, electrical insulation is an extremely important characteristic because it also leads to dielectric breakdown of the deflection yoke winding. This electrical insulation is greatly affected by changes in the humidity environment and the presence or absence of water on the deflection yoke surface. Being affected is a very serious problem. The present invention has been made in view of the present situation, even when used in a high humidity environment or even when water is present on the deflection yoke surface due to dew condensation or the like, the electrical insulation of the ferrite sheet is reduced, Alternatively, the present invention aims to provide a ferrite sheet for magnetic field correction of a deflection yoke that has excellent moisture resistance and water resistance that does not significantly reduce the electrical insulation of water liquid adhering to the ferrite sheet. (EN) A ferrite sheet for magnetic field correction of a deflection yoke, which is excellent in moisture resistance and water resistance as well as excellent in flexibility and flexibility.

[0009]

SUMMARY OF THE INVENTION The present invention, which has solved the above problems, provides a deflection yoke having a high heat resistance obtained by molding a binder resin containing a halogen group element and a resin containing ferrite powder made of soft ferrite. In the ferrite sheet for magnetic field correction, the chemical formula [M
_{g 6 Al 2 (OH) 16} CO 3 · 4H 2 O ] and the formula [Mg
_4,5 Al ₂ (OH) ₁₃ CO ₃ · 3.5H ₂ O] is added.

The blending amount of hydrotalside is preferably 3 to 15 parts by weight of hydrotalside with respect to 100 parts by weight of the binder resin.

As the binder resin, it is preferable to use chlorosulphonated polyethylene, which has excellent properties in all items such as flexibility, long-term heat resistance and electric insulation. Further, in order to reduce the cost, vinyl chloride can be used by adding an appropriate amount of flame retardant.

[0012]

[Function] 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 is useful for trapping and deactivating halogen group elements in synthetic resins. It is a compound that exhibits excellent ability,
Conventionally, it has been mainly used as an antacid for medicines. When such an amount of hydrotalside is mixed in the binder resin, halogen ions generated from the binder resin when exposed to a high temperature environment for a long time,
It is taken into hydrotalside by replacing CO _{3 in} the structure of hydrotalside. Since the halogen ions once captured do not desorb until the temperature rises above about 450 ° C, the halogen ions are completely inactivated under the operating temperature environment of the deflection yoke. The metal salt is not generated by being trapped by the oxide ferrite. In addition, since hydrotalcide that traps halogen ions does not have deliquescent properties, it does not absorb moisture in the atmosphere, and even when it contacts moisture adhering around the ferrite sheet, it can dissociate into metal ions and halogen ions. Absent.

As described above, the ferrite sheet to which an appropriate amount of hydrotalcide is added does not emit toxic halogen gas into the atmosphere even during long-term use in a high temperature environment, and due to the behavior of halogen ions, Since no metal salt is generated inside the sheet, the electrical insulation of the ferrite sheet will deteriorate even when used in a high humidity environment, and the electrical insulation of moisture adhering to the surroundings of the ferrite sheet due to condensation will also deteriorate. There is no.

When the blending amount of hydrotalside is 3 to 15 parts by weight of hydrotalside with respect to 100 parts by weight of the binder resin, the electrical insulating property in a high humidity environment, that is, the moisture resistance and the water resistance are obtained. Improve dramatically.

When chlorosulphonated polyethylene is used as the binder resin, a ferrite sheet excellent in flexibility and long-term heat resistance in addition to moisture resistance and water resistance can be obtained.

When vinyl chloride is used as the binder resin, an inexpensive ferrite sheet having moisture resistance and water resistance can be obtained.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below with reference to illustrated embodiments. FIG. 1 shows a general shape of a magnetic field correction ferrite sheet. The magnetic field compensating ferrite sheet 1 includes an adhesive layer 1 on the back surface of a sheet body 1a made of a resin containing ferrite.
This is a configuration in which b is laminated. Although the drawing shows a single sheet body, usually, a large number of release sheets are supplied in a state in which a large number of ferrite sheets 1 are arranged vertically and horizontally via groove grooves for breaking.

In the sheet body 1a, a plasticizer, a lubricant and a softening agent are added to a binder resin mainly composed of chlorosulfonated polyethylene having a chlorine content of less than 30% by weight, and hydrotalcide is added thereto. It is molded from a composition in which soft ferrite powder is dispersed and blended. The soft ferrite powder content is 70 to 8 of the total weight.
A known soft ferrite such as magnesium ferrite, nickel zinc ferrite and manganese zinc ferrite can be used as the soft ferrite selected from the range of 5% by weight. If the content of the soft ferrite powder is less than 70% by weight, the required magnetic properties cannot be obtained, and if it exceeds 85% by weight, the molding becomes difficult or the flexibility becomes insufficient and the composition becomes brittle. Is selected.

Chlorosulfonated polyethylene is a special rubber obtained by chlorinating and chlorosulfoning polyethylene by using chlorine and sulfurous acid gas, and has a structural formula shown in "Chemical Formula 1".

[0020]

[Chemical 1] Chlorosulfonated polyethylene is described in JIS. K711
The breaking strength according to the "Plastic tensile test method" of 3 is about 120 to 350 Kgf / cm ² , and the breaking elongation is 300.
~ 500%, it is extremely flexible, and it has a temperature environment of 110 ° C for over 100,000 hours or 12 hours.
It has a heat-resistant life of 40,000 hours or more under a temperature environment of 0 ° C. From the viewpoint of suppressing the dechlorination phenomenon in a high temperature environment and preventing the quality deterioration of chlorosulphonated polyethylene, the chlorine content is preferably less than 30% by weight, but the chlorine content is 30% by weight or more. Polyethylene is not excluded.

It is possible to use inexpensive vinyl chloride or other synthetic resin in place of chlorosulfonated polyethylene, but in this case, it is preferable to add a flame retardant from the viewpoint of enhancing heat resistance.

The hydrotalcide has the chemical formula [Mg
_{6 Al 2 (OH) 16 CO} 3 · 4H 2 O ] and the formula [Mg
_4,5 Al ₂ (OH) ₁₃ CO ₃ · 3.5H ₂ O] can be used, and the compounding amount thereof is hydrotalcide based on 100 parts by weight of the binder resin chlorosulfonated polyethylene. It is selected in the range of 3 to 15 parts by weight. If the blending amount of hydrotalside is less than 3 parts by weight, the halogen ion trapping effect is low, and on the other hand, 1
If it exceeds 5 parts by weight, the workability becomes poor and it becomes difficult to form it into a sheet shape.

As in the conventional case, such a ferrite sheet is directly attached to the winding surface of the deflection yoke by the adhesive layer 2 on the back surface. FIG. 2 shows a state in which the ferrite sheet 1 is attached to the surface of the winding b. In use, the winding b generates heat and heats the ferrite sheet, but since this ferrite sheet contains hydrotalside together with chlorosulphonated polyethylene, chlorine ions generated by heating are generated on the hydrotalside. To be captured. The heat generation temperature of the deflection yoke is at most 120 ° C to 1
Since the temperature is about 30 ° C., chlorine ions trapped on the hydrotalside are not desorbed. Therefore, since the chlorine ions are not captured by the ferrite to form a metal salt having deliquescent property, the electrical insulation of the ferrite sheet itself does not deteriorate and the ferrite sheet 1
The electric insulation of the moisture W adhering to the periphery due to dew condensation is not deteriorated, and dielectric breakdown does not occur even if the winding has pinholes P, P ....

Next, a test conducted to confirm the effect of the present invention will be described. The test was carried out by using a ferrite-containing resin composition having the composition shown in "Table 1" as shown in FIG.
Ferrite sheet test pieces having a thickness of 0 mm, a width of 15 mm, and a thickness of 0.4 mm were prepared, and these were used. The unit of the blending amount of each component in "Table 1" is parts by weight. The test reproduced the environment of the surface of the deflection yoke under the most severe conditions, and measured the change in electrical insulation under the environment. The electric insulation was measured by attaching electrodes on both sides of the test piece at intervals of 10 mm as shown in the figure and applying a voltage of DC 1000 V through the electrodes. The test procedure is as follows. Aging is performed in air at 120 ° C. for 1000 hours to dry the test piece. Measure the electrical resistance of the test piece. (Drying test) After boiling the test piece in boiling water at 100 ° C for 3 hours, the surface of the taken-out test piece is lightly wiped with water. Measure the electrical resistance of the test piece. (Water resistance test) "Table 1" shows the measurement results obtained by such a procedure.

[0025]

[Table 1] As can be seen from Table 1, the ferrite sheet test pieces of Examples 1 to 6 in which hydrotalside was added, compared with the conventional ferrite sheet test piece in which MgO was added, had an electrical insulation property (water resistance) after boiling. It can be confirmed that it has been improved. In particular, in Examples 2 to 6 in which the blending amount of hydrotalside was set to 3 parts by weight or more, it can be seen that the extremely excellent electrical insulation property was maintained even after the boiling. However, as shown in Example 6, when the blending amount of hydrotalside exceeded 15 parts by weight, the workability was deteriorated, and it was confirmed that it was slightly difficult to process into a sheet.

[0026]

EFFECTS OF THE INVENTION Since the magnetic field correcting ferrite sheet of the present invention contains hydrotalcide in the binder resin, toxic halogen gas does not diffuse into the atmosphere even during long-term use in a high temperature environment. Further, no metal salt is generated inside the ferrite sheet due to the behavior of halogen ions. Therefore, even when used in a high-humidity environment, the ferrite sheet has excellent moisture resistance and water resistance that does not reduce the electrical insulation of the ferrite sheet or the electrical insulation of moisture adhered to the periphery of the ferrite sheet due to dew condensation. Can be provided.

As described in claim 2, when the blending amount of hydrotalside is 3 to 15 parts by weight of hydrotalside with respect to 100 parts by weight of the binder resin, the electrical insulating property in a high humidity environment is obtained. That is, moisture resistance and water resistance are dramatically improved.

When chlorosulphonated polyethylene is used as the binder resin as described in claim 3, a ferrite sheet excellent in flexibility and long-term heat resistance in addition to moisture resistance can be obtained.

As described in claim 4, when vinyl chloride is used as the binder resin, an inexpensive ferrite sheet having moisture resistance and water resistance can be obtained.

[Brief description of drawings]

FIG. 1 is a perspective view showing one form of a magnetic field correction ferrite sheet.

FIG. 2 is a partially enlarged explanatory diagram showing a state in which a ferrite sheet for magnetic field correction is attached to the winding surface of the deflection yoke.

FIG. 3 is an explanatory diagram showing a method for measuring the electric insulation of a test piece of a magnetic field correction ferrite sheet

FIG. 4 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 b Winding P Pinhole W Moisture 1 Magnetic field correction ferrite sheet 1a Sheet body 1b Adhesive layer

Claims (4)

[Claims] 1. A ferrite sheet for magnetic field correction of a deflection yoke having high heat resistance, which is obtained by molding a binder resin containing a halogen group element and a ferrite powder-containing resin made of soft ferrite, wherein hydrotalcide is added to the binder resin. A ferrite sheet for magnetic field correction of a deflection yoke, which is characterized in that 2. The ferrite sheet for magnetic field correction of a deflection yoke according to claim 1, wherein 3 parts by weight to 15 parts by weight of hydrotalc are mixed with 100 parts by weight of the binder resin. 3. The ferrite sheet for magnetic field correction of a deflection yoke according to claim 1, wherein the binder resin is chlorosulfonated polyethylene. 4. The ferrite sheet for magnetic field correction of a deflection yoke according to claim 1, wherein the binder resin is vinyl chloride.