JP3865765B2 - Coated ferrite molded article and method for producing coated ferrite molded article - Google Patents

Description

  The present invention relates to a coated ferrite molded article and a method for producing a coated ferrite molded article, and particularly relates to a coated ferrite molded article excellent in impact resistance and scattering prevention and a method for producing a coated ferrite molded article.

  Conventionally, in order to suppress the effects of electromagnetic noise generated from circuit boards and casings on which electronic and electrical components are mounted, noise suppression parts such as ferrite beads, varistors, and choke coils are attached, or circuit boards and casings are mounted. For example, metallization has been implemented. However, ferrite molded products generally have problems of low insulation resistance and poor impact resistance.

  Accordingly, it has been proposed to cover a ferrite molded product applied to the core of a magnetic component such as a choke coil with a highly insulating resin or a case or bobbin formed with such a highly insulating resin. More specifically, a method of immersing a ferrite molded product in a fluororesin material or an epoxy resin material to form a resin film has been proposed, but there is a through portion for accommodating electrical wiring or the like in the ferrite molded product. In the case where it is provided, there has been a problem that the fluororesin material or the like causes the penetration portion to be buried.

  Therefore, in Japanese Patent Application Laid-Open No. 10-125539, as shown in FIG. 5, in the case of an E-core 350 made of MnZn-based ferrite and having an E-shape in a side view, a short plate portion 352 having a rectangular plan view. A rectangular parallelepiped leg 353 is erected along both side edges, and a columnar leg 354 is erected at the center of the plate 352, and a polyimide film is formed on the surface of the E core body 351 by vapor deposition. A method of forming 355 has been proposed.

In JP 2001-284877 A, a liquid resin can be formed by applying it to a circuit substrate or a casing, and the shape can be fixed and maintained after the shape processing. Also, a coating type electromagnetic shielding material containing ferrite powder has been proposed. More specifically, in the thermosetting resin or thermoplastic resin, the average particle diameter is 5 to 20 μm, and the general formula MO · Fe ₂ O ₄ or MFe ₂ O ₄ (where M is Fe, Mn , Ni, Co, Mg, Zn, and Cd) are added in the range of 20 to 90 vol%, and an electromagnetic shielding material having a viscosity of 30 to 30000 mPa · s is disclosed. ing.

  However, although the ferrite molded product disclosed in Japanese Patent Laid-Open No. 10-125539 is a magnetic part such as a choke coil, it cannot efficiently exhibit an electromagnetic wave shielding effect. In addition, since a polyimide film is formed around the ferrite by a vapor deposition method, there is a problem that the cost is extremely high and a special vapor deposition apparatus must be prepared, making mass production extremely difficult. It was.

  Further, the ferrite disclosed in Japanese Patent Application Laid-Open No. 2001-284877 is a fine powder having an average particle diameter of 5 to 20 μm, and is added to a coating type electromagnetic shielding material in order to exert an electromagnetic shielding effect. As a result, the electromagnetic wave shielding effect could not be effectively exhibited while fixing the electrical wiring inside the electrical product.

Furthermore, the ferrite described in JP-A-10-125539 and JP-A-2001-284877 has poor adhesion with a polyimide resin (polyimide film), and therefore, it still has poor impact resistance. There was also a problem that when pulverized, it easily scatters and may cause failure of electrical products.
Japanese Patent Laid-Open No. 10-125539 JP 2001-284877 A

Therefore, as a result of intensive studies on the above-described problems, a coating material made of a predetermined composition containing a polyimide resin, an epoxy compound, and an amine compound or acid anhydride is provided on the surface of the ferrite molded product. By limiting the addition amount of the epoxy compound and the amine compound or acid anhydride to a value within a predetermined range, it is not only convenient as a ferrite bead but also excellent in impact resistance and scattering prevention. The present inventors have found that a coated ferrite molded product can be obtained and have completed the present invention.

That is, the present invention has excellent impact resistance and anti-scattering properties due to the synergistic effect of the polyimide resin used as the coating material and the epoxy compound, while fixing the electric wiring inside the electric product. An object of the present invention is to provide a coated ferrite molded product capable of exhibiting an electromagnetic wave shielding effect and a production method for efficiently obtaining such a coated ferrite molded product.

According to the present invention, the surface is provided with a coating material composed of a predetermined composition containing a polyimide resin, an epoxy compound, and an amine compound or an acid anhydride, and the epoxy compound and the amine compound or A coated ferrite molded article in which the amount of acid anhydride added is limited to a value within a predetermined range is provided, and the above-described problems can be solved.

That is, the surface of the ferrite molded article is provided with a coating material composed of a polyimide resin, an epoxy compound, and a predetermined composition containing an amine compound or an acid anhydride, and the epoxy compound and the amine compound or more limiting the amount of the acid anhydride to the value of the predetermined range, not only the usability is good, so that impact resistance and shatterproof excellent in coated ferrite molded article is obtained. Therefore, due to the synergistic effect of the polyimide resin used as the coating material and the epoxy compound, it has excellent impact resistance and anti-scattering properties, and also has an electromagnetic shielding effect while fixing the electrical wiring inside the electrical product. It is possible to provide a coated ferrite molded product that can exhibit the above.

In constituting the coated ferrite molded article of the present invention, the thermosetting composition or the ultraviolet curable composition further contains a lubricant, and the addition amount of the lubricant is 100 parts by weight of the polyimide resin. A value within the range of 1 to 30 parts by weight is preferred.

  With this configuration, it is possible to provide a coated ferrite molded article that can be appropriately plasticized and that has a good balance of impact resistance, scattering prevention, and adhesion. Moreover, since the slip property on the surface is also improved, when a through-hole is provided in the ferrite molded product, electric wiring or the like can be easily inserted.

  In constituting the coated ferrite molded product of the present invention, the epoxy compound contains a pigment, and the added amount of the pigment is set to a value within the range of 10 to 120 parts by weight with respect to 100 parts by weight of the epoxy compound. Is preferred.

  With such a configuration, it is possible to provide a coated ferrite molded product that achieves predetermined concealability and colorization, and further has a better balance between impact resistance, scattering prevention, and heat resistance.

  In forming the coated ferrite molded article of the present invention, it is preferable that the ferrite has a flat plate shape or a rectangular parallelepiped shape, and in the case of the rectangular parallelepiped shape, it is preferable to provide through holes each having openings on at least two surfaces.

  By configuring in this way, it can be attached to the surface of the casing of the electric product, and electric wiring etc. can be easily inserted into the through part in a rectangular parallelepiped ferrite molded product to obtain an excellent electromagnetic shielding effect Can do.

In constructing the coated ferrite molded product of the present invention, the thickness of the coating material is preferably set to a value within the range of 0.1 to 100 μm.

  By comprising in this way, the coated ferrite molded product with a favorable balance of impact resistance and scattering prevention property can be provided.

  In constructing the coated ferrite molded product of the present invention, the coverage by the coating material is preferably set to a value in the range of 10 to 90% when the surface area of the ferrite is 100%.

  By comprising in this way, the coated ferrite molded product with a favorable balance of impact resistance and scattering prevention property can be provided. Moreover, even if a relatively small penetration portion is provided, the risk of the penetration portion being buried can be reduced by adjusting the coverage.

Another aspect of the present invention is a method for producing a coated ferrite molded article characterized by sequentially including the following steps (1) to (3).
(1) Step of preparing a ferrite molded product (2) While moving the ferrite molded product, a thermosetting composition or an ultraviolet curable composition containing a polyimide resin and an epoxy compound with respect to the surface thereof. The addition amount of the epoxy compound is set to a value in the range of 1 to 80 parts by weight with respect to 100 parts by weight of the polyimide resin, and the amine compound or acid is added to the thermosetting composition or the ultraviolet curable composition. A thermosetting composition or an ultraviolet curable composition further containing an anhydride, and the addition amount of the amine compound or acid anhydride is a value within the range of 1 to 30 parts by weight with respect to 100 parts by weight of the polyimide resin. by heat curing or ultraviolet curing step (3) ferrite molded article thermosetting composition or ultraviolet curable composition is applied to apply the gender composition, Step of the covering ferrite moldings

  That is, while moving the prepared ferrite molded product, a predetermined thermosetting composition or an ultraviolet curable composition is applied, and then the ferrite molded product is heat-cured or ultraviolet-cured, whereby a relatively thin coating material Even so, it can be formed to a uniform thickness. Moreover, even when a relatively small penetration portion is provided, there is a possibility that the penetration portion may be buried by the thermosetting composition or the ultraviolet curable composition by covering the ferrite molded product while moving it. Can be reduced.

  In carrying out the method for producing a coated ferrite molded product according to the present invention, the ferrite molded product is rotated in a plane or vertically in a stirring vessel or on a conveying path, while the thermosetting composition or ultraviolet curing is performed on the surface. It is preferred to apply the sex composition at least once.

  By carrying out in this way, even a relatively thin coating material can be formed with a more uniform thickness, and the possibility of burying the penetrating portion is further reduced.

  Embodiments relating to the coated ferrite molded article and the method for producing the same according to the present invention will be specifically described below with reference to the drawings as appropriate.

[First embodiment]
In the first embodiment, as illustrated in FIG. 1 (a), a coating material 14 composed of a thermosetting composition or an ultraviolet curable composition containing a polyimide resin and an epoxy compound is used as a ferrite molded product. The amount of the epoxy compound added to a value within the range of 1 to 80 parts by weight with respect to 100 parts by weight of the polyimide resin, and the thermosetting composition or the ultraviolet curable composition The product further contains an amine compound or acid anhydride, and the added amount of the amine compound or acid anhydride is within a range of 1 to 30 parts by weight with respect to 100 parts by weight of the polyimide resin. a coated ferrite molded article 10, characterized in.

1. Ferrite molded product The material of the ferrite constituting the ferrite molded product 12 illustrated in FIG. 1 (a) is not particularly limited. For example, the general formula MO · Fe ₂ O ₄ or MFe ₂ O ₄ (here, M is a soft ferrite represented by a metal selected from at least one of Fe, Mn, Ni, Co, Mg, Zn, and Cd.

  Further, the ferrite molded product made of such a material is processed into a desired shape such as a plate shape or a rod shape as shown in FIG. 1 (b) by various methods such as rolling, casting, drawing or casting, The adhesive layer 12c may be provided on the lower surface.

  Or as shown to Fig.1 (a), it is a rectangular parallelepiped shape, Comprising: In the case of a rectangular parallelepiped shape, it is also preferable to provide the through-hole 12b which each has the opening part 12a in at least 2 surface. If comprised in this way, as shown in FIG.1 (c), the outstanding electromagnetic wave shielding effect can be acquired only by letting the electrical wiring 15 pass through the inside of the through-hole 12b.

2. Coating Material (1) Composition The coating material 14 illustrated in FIG. 1 (a) is composed of a thermosetting composition or an ultraviolet curable composition containing a polyimide resin and an epoxy compound. And

That is, due to the synergistic effect of the polyimide resin used as the coating material and the epoxy compound, it has excellent impact resistance and anti-scattering properties, and, for example, electromagnetic waves while fixing electrical wiring inside the electrical product. This is to provide a coated ferrite molded product that can exhibit a shielding effect.

  Note that it is not necessary to cover the entire surface of the ferrite molded product 12 with the coating material 14, and the ferrite molding product 12 may be partially coated as long as predetermined impact resistance and anti-scattering properties are obtained. Rather, as shown in FIG. 1 (a), when the through-hole 12b having the opening 12a is provided, it is difficult to penetrate the electric wiring 15 if the inner surface of the through-hole 12b is covered. It may become. Therefore, it is preferable that the coverage by the coating material 14 is a value within a range of 10 to 90% when the total surface area of the ferrite molded product 12 is 100%.

  However, when the ferrite molded product 12 has a flat plate shape, it is not necessary to consider the burying of the opening, so that the coverage by the coating material 14 is preferably 100%.

  Here, as a preferable polyimide resin constituting the covering material 14, a polyamic acid as a precursor and a polyamideimide resin as a derivative are used, and a condensation composed of an ester dianhydride and an amine compound (diamine compound). Things. More specifically, 2,2-bis (4-hydroxyphenyl) propanedibenzoate-3,3 ′, 4,4′-tetracarboxylic dianhydride, p-phenylenebis ( Trimellitic acid monoester anhydride), 3,3 ′, 4,4′-ethylene glycol benzoate tetracarboxylic dianhydride, 4,4′-biphenylenebis (trimellitic acid monoester anhydride), 1,4- Naphthalenebis (trimellitic acid monoester anhydride), 1,2-ethylenebis (trimellitic acid monoester anhydride), 1,3-trimethylenebis (trimellitic acid monoester anhydride), 1,4-tetra Methylene bis (trimellitic acid monoester anhydride), 1,5-pentamethylene bis (trimellitic acid monoester anhydride), 1,6-hex Methylenebis (trimellitic acid monoester anhydride), and the like.

  As the amine compound, 3,3′-bis (aminophenoxyphenyl) sulfone, 4,4′-diaminodiphenylsulfone, 1,3-bis (3-aminophenoxy) benzene, oxydianiline, diaminodiphenylmethane, bis (2-aminoethyl) polydimethylsiloxane, bis (3-aminopropyl) polydiphenylsiloxane and the like can be mentioned.

  Moreover, as a preferable epoxy resin, a glycidyl ether type epoxy resin, a glycidyl ester type epoxy resin, or a glycidyl amine type epoxy resin can be used. Examples of the main raw material of the epoxy resin include propylene glycol, tetraphenylethane, hexahydrophthalic anhydride, bisphenol A, hydrogenated bisphenol A, bisphenol F, hydrogenated bisphenol F, tetrabromobisphenol A, dimer acid, Diaminodiphenylmethane, isocyanuric acid, p-aminophenol, p-oxybenzoic acid and the like can be used.

  Further, since a thermosetting composition or an ultraviolet curable composition containing a polyimide resin can be handled as a solution, sulfoxide solvents such as dimethyl sulfoxide and diethyl sulfoxide, N, N-dimethylformamide, N, N-diethylformamide , N, N-dimethylacetamide, N, N-diethylacetamide, N-methyl-2-pyrrolidone, phenol, cresol, xinol, halogenated phenol, catechol, hexamethylphosphoramide, γ-butyrolactone, tetrahydrofuran, etc. Is preferably added.

In addition, in the thermosetting composition or the ultraviolet curable composition constituting the coating material, the amount of the epoxy compound added is preferably in the range of 1 to 80 parts by weight with respect to 100 parts by weight of the polyimide resin. .

  The reason for this is that when the amount of the epoxy compound added is less than 1 part by weight, the hardness of the coating material decreases, the adhesion of the coating material to the ferrite molded product decreases, or the heat resistance of the coating material. This is because there is a case where the value decreases.

  On the other hand, when the amount of the epoxy compound added exceeds 80 parts by weight, the impact resistance of the coating material is lowered, it is difficult to form a film with a uniform thickness, or the chemical resistance is lowered. It is because there is a case to do.

  Therefore, the addition amount of the epoxy compound is more preferably set to a value within the range of 5 to 50 parts by weight, and further preferably set to a value within the range of 10 to 30 parts by weight per 100 parts by weight of the polyimide resin.

  Here, with reference to FIG. 2, the influence of the addition amount of the epoxy compound (epoxy resin pigment) on the characteristics of the coated ferrite molded product will be described.

  That is, the horizontal axis of FIG. 2 shows the addition amount (parts by weight) of the epoxy compound relative to 100 parts by weight of the polyimide resin, and the left vertical axis shows the pencil hardness (H). The right vertical axis shows the impact resistance (relative value).

  As can be easily understood from FIG. 2, as the amount of the epoxy compound added to the polyimide resin increases, the value of the pencil hardness increases while the impact resistance (relative value) gradually decreases. There is a trend.

  Therefore, in order to achieve a good balance between pencil hardness and impact resistance, the addition amount of the epoxy compound is preferably set to a value in the range of 1 to 80 parts by weight per 100 parts by weight of the polyimide resin. It can be said that it is more preferable to set the value within the range of 5 to 50 parts by weight.

  Further, in the thermosetting composition or the ultraviolet curable composition, an amine compound or an acid anhydride as a polyimide resin raw material is separately included, and the added amount of the amine compound or the like is 100 parts by weight of the polyimide resin. A value within the range of 1 to 30 parts by weight is preferred.

  The reason for this is that when the amount of the amine compound or the like is less than 1 part by weight, the effect of addition may not be exhibited.

  On the other hand, when the added amount of the amine compound or the like exceeds 30 parts by weight, it may be difficult to form a film with a uniform thickness or the wet resistance may be lowered.

  Therefore, it is more preferable to set the addition amount of the amine compound or acid anhydride to a value in the range of 2 to 20 parts by weight per 100 parts by weight of the polyimide resin, and to a value in the range of 3 to 15 parts by weight. Is more preferable.

Further, the thermosetting composition or the ultraviolet curable composition further contains a lubricant, and the additive amount of the lubricant is a value within the range of 1 to 30 parts by weight with respect to 100 parts by weight of the polyimide resin. It is preferable that

The reason for this is that, by including a predetermined amount of lubricant, it becomes easy to adjust water repellency and mechanical properties. However, when the amount of the lubricant added is less than 1 part by weight, the additive effect may not be manifested. Because there is.

  On the other hand, when the added amount of the lubricant exceeds 30 parts by weight, it may be difficult to form a film with a uniform thickness, or the compatibility between the components may be reduced.

  Therefore, it is more preferable to set the addition amount of the lubricant to a value within the range of 2 to 25 parts by weight, and even more preferably within a range of 3 to 20 parts by weight per 100 parts by weight of the polyimide resin.

  Such lubricants include fluorinated acrylate resins, vinylidene fluoride resins, fluorinated urethane resins, fluorinated amino resins, polytrifluoroethylene resins, polytetrafluoroethylene resins, polyhexafluoropropylene resins, and fluorinated ethylenes. Fluorine resins such as propylene copolymer resin, polychlorotrifluoroethylene resin, ethylene-tetrafluoroethylene copolymer resin, tetrafluoroethylene-hexafluoropropylene copolymer resin, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin .

  In addition to the above-described fluororesin, it is also preferable to include, for example, graphite, molybdenum disulfide, boron nitride, liquid paraffin, silicone oil, fluorine oil, mechanical oil, castor oil, oleic acid, and the like as the lubricant.

  Moreover, it is also preferable to further include other additives in the thermosetting composition or the ultraviolet curable composition.

  For example, in the case of forming a thin film having a uniform thickness, it is preferable that a diluent solvent such as alcohols, ketones, glycols and the like is included as an additive.

  To adjust viscosity and mechanical properties, inorganic fillers such as glass, quartz, aluminum hydroxide, alumina, kaolin, talc, calcium carbonate, calcium silicate, magnesium hydroxide, acrylic resin powder, epoxy resin powder Organic fillers such as polyester resin powders; Colorants typified by pigments and dyes such as carbon black, Bengala, phthalocyanine blue, cream yellow, and titanium dioxide; metal powders; lubricants; mold release agents; surfactants; It is preferable to add one kind of agent or a combination of two or more kinds.

  In addition, when trying to colorize the coated ferrite molded product, for example, titanium oxide, titanium red, cadmium yellow, cobalt oxide, iron oxide, ferrite, metal-free phthalocyanine pigment, aluminum phthalocyanine pigment, titanium phthalocyanine pigment It preferably contains a colorant such as iron phthalocyanine pigment, cobalt phthalocyanine pigment, nickel phthalocyanine pigment, tin phthalocyanine pigment, copper phthalocyanine pigment.

  Further, for example, it is also preferable to add another thermosetting resin or a metal alkoxide in order to improve film formability or improve adhesion. More specifically, examples of the thermosetting resin include one kind alone or a combination of two or more kinds such as phenol resin, maleimide resin, urea resin, vinyl ester resin, silicone compound or unsaturated polyester resin.

(2) Thickness Regarding the thickness of the covering material, for example, the thickness is preferably set to a value within the range of 0.1 to 100 μm.

  The reason for this is that when the thickness of the covering material is less than 0.1 μm, impact resistance and anti-scattering properties may be reduced.

On the other hand, if the thickness of the covering material exceeds 100 μm, it is difficult to form a uniform film thickness, or even if a through-hole for passing electrical wiring or the like is provided, This is because the mouth may be buried.

Accordingly, the thickness of the covering material is more preferably set to a value within the range of 1 to 100 μm, and further preferably set to a value within the range of 10 to 100 μm.

(3) Mechanical strength Regarding the mechanical strength of the coating material, it is preferable to set the pencil hardness measured in accordance with JIS K5400 to a value in the range of 1 to 5H.

  The reason for this is that when the pencil hardness of the covering material is less than 1H, the mechanical strength decreases, and the impact resistance and scattering prevention properties may also decrease accordingly.

  On the other hand, when the pencil hardness of the covering material exceeds 5H, the adhesion to the ferrite molded product may be lowered, or the selectivity of usable materials may be remarkably narrowed.

  Therefore, it is more preferable to set the pencil hardness of the covering material to a value within the range of 2 to 4H.

  Moreover, it is preferable to make the tensile elongation at 25 degreeC of a coating | covering material into the value within the range of 50 to 150%.

  The reason for this is that when the tensile elongation of the covering material is less than 50%, the mechanical strength decreases, and the impact resistance and anti-scattering properties may decrease accordingly.

  On the other hand, if the tensile elongation of the covering material exceeds 150%, the selectivity of usable materials may be significantly narrowed.

  Therefore, the tensile elongation of the covering material is more preferably set to a value within the range of 70 to 120%, and further preferably set to a value within the range of 80 to 100%.

Moreover, it is preferable to make the tensile strength measured based on JISK5400 of a coating | covering material into the value within the range of 1-100 kgf / mm < ² >.

The reason for this is that when the tensile strength of the covering material is less than 1 kgf / mm ² , the mechanical strength is lowered, and the impact resistance and anti-scattering properties may be lowered accordingly.

On the other hand, if the tensile strength of the covering material exceeds 100 kgf / mm ² , the selectivity of usable materials may be remarkably narrowed.

Therefore, it is more preferable to set the tensile strength of such dressings a value within the range of 5~80kgf / mm ^2, still more preferably a value within the range of 10~50kgf / mm ^2.

Moreover, it is preferable to make the tensile elasticity modulus measured based on JISK5400 of a coating | covering material into the value within the range of 100-500 kgf / mm < ² >.

The reason for this is that when the tensile modulus of the coating material is less than 100 kgf / mm ² , the mechanical strength decreases, and the impact resistance and anti-scattering properties may decrease accordingly.

On the other hand, when the tensile elastic modulus of the covering material exceeds 500 kgf / mm ² , the selectivity of usable materials may be remarkably narrowed.

Therefore, it is more preferable to set the tensile modulus of such dressings a value within the range of 120~300kgf / mm ^2, still more preferably a value within the range of 150~250kgf / mm ^2.

(4) Electrical characteristics Moreover, regarding the electrical characteristics of the coating material, the volume resistivity is preferably set to a value of 1 × 10 ¹³ Ω · cm or more.

The reason for this is that when the volume resistivity of the covering material is less than 1 × 10 ¹³ Ω · cm, the electrical characteristics decrease, and the impact resistance and anti-scattering properties after a long time decrease accordingly. This is because there are cases.

  However, if the volume resistivity of the covering material becomes excessively large, the curing conditions and the types of usable resins may be excessively limited.

Accordingly, the volume resistivity of the covering material is more preferably set to a value within the range of 1 × 10 ¹⁴ to 1 × 10 ¹⁸ Ω · cm, and within the range of 5 × 10 ¹⁴ to 1 × 10 ¹⁷ Ω · cm. More preferably, it is a value.

  Moreover, it is preferable that the dielectric breakdown pressure of the coating material is set to a value of 50 kV / mm or more.

  The reason for this is that when the dielectric breakdown pressure of the covering material is less than 50 kV / mm, the electrical characteristics are lowered, and the impact resistance and anti-scattering properties after a long time may be lowered accordingly. It is.

  However, when the dielectric breakdown pressure of the covering material is excessively increased, the curing conditions and the types of resins that can be used may be excessively limited.

  Therefore, it is more preferable to set the dielectric breakdown pressure of the covering material to a value within the range of 80 to 200 kV / mm, and it is even more preferable to set the value within the range of 100 to 180 kV / mm.

[Second Embodiment]
The second embodiment of the present invention is a method for producing a coated ferrite molded article including the following steps (1) to (3), as shown in FIG. 3 in its production flowchart (S1 to S5).
(1) Step of preparing a ferrite molded product (S1 to S2)
(2) While moving the ferrite molded product, a thermosetting composition or an ultraviolet curable composition containing a polyimide resin and an epoxy compound with respect to the surface thereof, with respect to 100 parts by weight of the polyimide resin The addition amount of the epoxy compound is set to a value within the range of 1 to 80 parts by weight, and the thermosetting composition or the ultraviolet curable composition further contains an amine compound or an acid anhydride, and the amine A step of applying a thermosetting composition or an ultraviolet curable composition in which the addition amount of the compound or acid anhydride is set to a value in the range of 1 to 30 parts by weight with respect to 100 parts by weight of the polyimide resin (S3).
(3) Steps (S4 to S5) in which a ferrite molded article to which a thermosetting composition or an ultraviolet curable composition is applied is heat-cured or ultraviolet-cured to form a coated ferrite molded article.

1. Step of Preparing Ferrite Molded Product As shown in S2, the surface of the ferrite molded product molded in S1 in FIG. 3 is preferably cleaned in advance. That is, first, as shown in S2, fats and oils are degreased using an organic solvent such as trichlorethylene and trichloroethane, or an aqueous detergent such as an alkaline detergent, to activate the surface of the ferrite molded product. preferable.

2. Step of applying thermosetting composition or UV curable composition Next, as shown in S3 in FIG. 3, applying the thermosetting composition or UV curable composition to the surface of the ferrite molded product Is preferred.

  For example, it is preferable to apply a thermosetting composition or an ultraviolet curable composition to the surface of a ferrite molded article using a tumbler coater as shown in FIG.

3. Step of Curing Thermosetting Composition or UV Curable Composition Next, as shown in S4 in the manufacturing flowchart of FIG. 3, the ferrite molded product to which the thermosetting composition or the UV curable composition is applied is heated. It is preferable to form a coating material by curing or ultraviolet curing.

  Specifically, as shown in FIG. 4 (a), a tumbler coater 100 having an internal space 120 configured to accommodate a ferrite molded product and a rotating member 113 with an openable / closable door 103 is provided. It is preferable to use it. Therefore, a plurality of stirring baffles 107 a and 107 b and a transport baffle 105 are provided in the internal space 120, and the rotating member 113 is rotated in a predetermined rotation direction by the rotating device 111 below the communicating portion 109. It is possible. Further, by opening the door 103, a thermosetting composition or an ultraviolet curable composition that becomes a ferrite molded product or a covering material can be accommodated in the rotating member 113 using the charging device 101. Then, by rotating the rotating member 113 horizontally around the axis ab with the door 103 closed, the coating material 14 is made to have a uniform thickness on the surface of the ferrite molded product mainly using centrifugal force. Can be applied.

  Further, as shown in FIG. 4 (b), a tumbler coater 200 having an internal space 220 configured to accommodate a ferrite molded product and a rotating member 213 with an openable / closable door 203, A plurality of stirring baffles 207 a and 207 b and a transport baffle 205 may be provided in the internal space 220, and the rotating member 213 may be rotated by the rotating device 211 on the side surface of the communication unit 209. Therefore, in the state where the door 203 is opened, the charging device 201 can be used to store the ferrite molded product, the thermosetting composition or the ultraviolet curable composition serving as the coating material in the rotating member 213. The coating material 14 is applied to the surface of the ferrite molded product mainly using centrifugal force and gravity by rotating the rotating device 211 vertically around the axis a′b ′ with the door 203 closed. can do.

When tumbler coaters 100 and 200 as shown in FIGS. 4 (a) and 4 (b) are used, the thermosetting composition is heated by heating at a temperature of 50 to 300 ° C. for 10 minutes to 10 hours. It is preferable to form a coating material having a predetermined thickness by curing.
Moreover, when making it ultraviolet cure, it is preferable to harden an ultraviolet curable composition by making the exposure amount into the value within the range of 50-1,000 mJ / cm < ² >, for example. Furthermore, in the case of ultraviolet curing, since the active state of the photopolymerization initiator can be maintained for a long time, exposure in a vacuum state or an inert gas is also preferable.
In addition, as shown as S5 at the end of the manufacturing process, an inspection process (including an evaluation process) is provided. For example, a coated ferrite molded product that does not meet predetermined characteristics and dimensional standards using an optical microscope or an automatic inspection device. Is preferably excluded.

[Example 1]
1. Preparation of Coated Ferrite Molded Product A flat iron plate (vertical 20 cm, horizontal 20 cm, thickness 1 mm) was prepared as a ferrite molded product, and its surface was degreased using trichlorethylene and an alkaline cleaner.

  Next, after the ferrite molded product was accommodated in the tumbler coater, 100 parts by weight of the polyimide resin, 20 parts by weight of the epoxy compound, 5 parts by weight of the amine compound, and an organic solvent ( (THF) and a thermosetting composition containing 700 parts by weight, while being sprayed in 20 portions, heated at 250 ° C. for 120 minutes to obtain a thickness as shown in FIG. A coated ferrite molded article having a 70 μm coating material was prepared.

  The thermosetting composition was separately heat-cured under the same conditions to form a film-like material, and the tensile strength, tensile elongation, and tensile elastic modulus were measured in accordance with JIS K5400.

2. Evaluation of coated ferrite molded product (1) Impact resistance evaluation The obtained coated ferrite molded product (number of samples: 10) is naturally dropped from a height of 1.8 m, and the impact resistance is evaluated according to the following criteria. Carried out.
A: No cracks were observed in 10 samples.
○: No cracks were observed in 8 or more samples.
Δ: No cracks were observed in 6 or more samples.
X: Cracks were observed in 5 or more samples.

(2) Adhesion evaluation The obtained coated ferrite molded product (number of samples: 10) was subjected to a cross-cut test (1 mm cross hatch) in accordance with JIS K5400, and the adhesion evaluation was performed in accordance with the following criteria. did.
A: The number of peeling is 0/100 grid.
○: The number of peeling is 1 to 3/100 grids.
Δ: The number of peeling is 4 to 10/100 grid.
X: The number of peeling is more than 10 / 100th grid.

(3) Pencil hardness About the obtained coated ferrite molded product (sample number: 10), pencil hardness was measured based on JIS K5400, and it calculated as an average value.

(4) Heat resistance evaluation The obtained coated ferrite molded product (number of samples: 10) is housed in an oven maintained at a temperature of 250 ° C., and appearance changes (peeling, cracking, discoloration, etc.) are performed every predetermined time. Observed and evaluated the heat resistance in light of the following criteria.
A: No significant change in appearance was observed after 1,000 hours.
○: No significant change in appearance was observed after 500 hours.
Δ: No significant change in appearance was observed after 300 hours.
X: Significant changes in appearance (peeling, cracks, etc.) were observed before 300 hours.

(5) Humidity resistance evaluation The obtained coated ferrite molded product (number of samples: 10) is housed in a temperature and humidity oven maintained at a temperature of 49 ° C. and a humidity of 98%, and the appearance changes (peeling) every predetermined time. , Cracks, discoloration, etc.) were observed, and the moisture resistance was evaluated according to the following criteria.
A: No significant change in appearance was observed after 1,000 hours.
○: No significant change in appearance was observed after 500 hours.
Δ: No significant change in appearance was observed after 300 hours.
X: Significant changes in appearance (peeling, cracks, etc.) were observed before 300 hours.

(6) Evaluation of salt water resistance The obtained coated ferrite molded product (number of samples: 10) is subjected to a salt spray test (SST test, temperature: 35 ° C., concentration 5%) based on JIS Z2371, and appearance every predetermined time. Changes (peeling, cracks, discoloration, etc.) were observed, and salt water resistance was evaluated in light of the following criteria.
A: No significant change in appearance was observed after 1,000 hours.
○: No significant change in appearance was observed after 500 hours.
Δ: No significant change in appearance was observed after 300 hours.
X: A remarkable change in appearance was observed before 300 hours.

(7) Evaluation of chemical resistance The obtained coated ferrite molded articles (number of samples: 10) were immersed in sulfuric acid (20% solution), methyl ethyl ketone (MEK), and sodium chloride (saturated aqueous solution) for a predetermined time. After that, changes in appearance (peeling, cracks, discoloration, etc.) were observed, and chemical resistance evaluation was performed in light of the following criteria.
A: After 300 hours, no change in appearance was observed for all chemicals.
○: After 168 hours, no change in appearance was observed for all chemicals.
Δ: After 100 hours, no change in appearance was observed for all chemicals.
X: Appearance change was observed with any of the chemicals before 100 hours had passed.

(8) Electrical property evaluation The volume resistivity (Ω · cm) and dielectric breakdown pressure (kV / mm) of the obtained coated ferrite molded product (number of samples: 10) were measured and calculated as average values.

[Examples 2 to 5]
In Examples 2-5, the influence of the addition amount of an epoxy compound was examined. That is, in Example 2, the addition amount of the epoxy compound is 5 parts by weight with respect to 100 parts by weight of the polyimide resin, and in Example 3, the addition amount of the epoxy compound is similarly 10 parts by weight. In the same manner as in Example 1, except that the addition amount of the epoxy compound was 30 parts by weight, and in Example 5, the addition amount of the epoxy compound was similarly 50 parts by weight. Number: 10) was made and each evaluation was performed.

[Examples 6 to 8]
In Examples 6-8, the influence of the addition amount of an amine compound was examined. That is, in Example 6, the addition amount of the amine compound is 1 part by weight with respect to 100 parts by weight of the polyimide resin, and in Example 7, the addition amount of the amine compound is similarly 10 parts by weight. In the same manner, except that the addition amount of the amine compound was 20 parts by weight, coated ferrite molded articles (number of samples: 10) were respectively prepared in the same manner as in Example 1, and each evaluation was performed.

[Examples 9 to 11]
In Examples 9-11, the influence of the thickness of the coating material was examined.
That is, in Example 9, the thickness of the coating material was 20 μm, in Example 10, the thickness of the coating material was 30 μm, and in Example 11, the thickness of the coating material was 50 μm, In the same manner as in Example 1, coated ferrite molded articles (number of samples: 10) were prepared and evaluated.

[Comparative Example 1]
In Comparative Example 1, a coated ferrite molded article (number of samples: 10) was prepared and evaluated in the same manner as in Example 1 except that no epoxy compound was added.

According to the coated ferrite molded product and the method for producing a coated ferrite molded product of the present invention, by providing a coating material composed of a predetermined composition containing a polyimide resin and an epoxy compound on the surface of the ferrite molded product. In addition to being easy to use as ferrite beads and the like, it has become possible to efficiently obtain a coated ferrite molded product having excellent impact resistance and anti-scattering properties.
Therefore, the coated ferrite molded product of the present invention is used in various electrical products and can exhibit an excellent electromagnetic wave shielding effect over a long period of time.

It is a figure provided in order to demonstrate the form of a coated ferrite molded product. It is a figure provided in order to demonstrate the addition effect of an epoxy compound. It is a figure provided in order to demonstrate the manufacture flowchart of a coated ferrite molded product. It is a figure provided in order to demonstrate a tumbler coater. It is a figure provided in order to demonstrate the form of the conventional coated ferrite molded product.

Claims (8)

The surface is provided with a coating material composed of a thermosetting composition or an ultraviolet curable composition containing a polyimide resin and an epoxy compound,
While making the addition amount of the said epoxy compound into the value within the range of 1-80 weight part with respect to 100 weight part of said polyimide resins,
The thermosetting composition or ultraviolet curable composition further contains an amine compound or acid anhydride, and the added amount of the amine compound or acid anhydride is 1 to 100 parts by weight of the polyimide resin. A value within the range of 30 parts by weight,
Coated ferrite molded product characterized by The thermosetting composition or the ultraviolet curable composition further contains a lubricant, and the additive amount of the lubricant is a value within the range of 1 to 30 parts by weight with respect to 100 parts by weight of the polyimide resin. The coated ferrite molded article according to claim 1, wherein:   The pigment is contained in the epoxy compound, and the addition amount of the pigment is set to a value within a range of 10 to 120 parts by weight with respect to 100 parts by weight of the epoxy compound. The coated ferrite molded product as described.   The said ferrite molded product is flat plate shape or rectangular parallelepiped shape, Comprising: When it is a rectangular parallelepiped shape, it has a through-opening which has an opening part in at least two surfaces, respectively. Coated ferrite molded product.   The thickness of the said coating | covering material shall be a value within the range of 0.1-100 micrometers, The coated ferrite molded article as described in any one of Claims 1-4 characterized by the above-mentioned.   The coverage with the coating material is set to a value within a range of 10 to 90% when a surface area of the ferrite molded product is set to 100%. Coated ferrite molded product. A method for producing a coated ferrite molded article comprising the following steps (1) to (3) in sequence.
(1) Step of preparing a ferrite molded product (2) While moving the ferrite molded product, a thermosetting composition or an ultraviolet curable composition containing a polyimide resin and an epoxy compound with respect to the surface thereof. The addition amount of the epoxy compound is set to a value in the range of 1 to 80 parts by weight with respect to 100 parts by weight of the polyimide resin, and the amine compound or acid is added to the thermosetting composition or the ultraviolet curable composition. A thermosetting composition or an ultraviolet curable composition further containing an anhydride, and the addition amount of the amine compound or acid anhydride is a value within the range of 1 to 30 parts by weight with respect to 100 parts by weight of the polyimide resin. (3) applying a heat-curing composition or a UV-curing composition to the ferrite molded article to which the thermosetting composition or the ultraviolet-curing composition is applied, Step of the covering ferrite moldings   The ferrite molded article is applied at least once to the surface of the ferrite molded article while rotating or vertically rotating in a stirring vessel or on a conveyance path. A method for producing a coated ferrite molded article according to claim 7.

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