JP2009260122A - High voltage coil and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high voltage coil which has a high reliability, and simultaneously is manufactured at a lower cost and a better productivity than before, and its manufacturing method. <P>SOLUTION: In the high voltage coil, a casting thermosetting resin composition is cast into a coil component obtained by winding a primary coil and a secondary coil on a magnetic core to be cured, and the cast and cured coil component is coated with a coating resin. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a high voltage coil and a method for manufacturing the same, and more particularly to an ignition coil and a method for manufacturing the same.

  For example, in an automotive ignition coil, a coil body composed of an iron core, a primary coil, and a secondary coil is housed in a case to protect and insulate coil components, and an epoxy resin composition is cast into the case. (See, for example, Patent Documents 1 and 2). When casting an epoxy resin composition, vacuum casting is generally used so that voids do not occur.

  In recent years, as ignition coils for automobiles have become more multifunctional, the demand for reliability has been increasing. On the other hand, there are increasing demands for cost reduction and productivity improvement. Usually, since a case is used for injecting resin into a coil, the process becomes complicated and the material cost increases, and the adhesion between the case and the resin may be impaired due to shrinkage during curing. Therefore, it has also been proposed to manufacture a flyback transformer by casting two types of resins having different filler amounts without using a case (see, for example, Patent Document 3). However, a technology that can respond to the ignition coil has not yet been obtained.

JP 2002-15928 A JP-A-7-126493 JP-A-5-82377

  The present invention has been proposed under the circumstances as described above, and has a high reliability and a high voltage coil that can be manufactured at low cost and with high productivity compared to the prior art, and a manufacturing method thereof, Furthermore, it aims at providing the thermosetting resin composition for casting suitable for this high voltage coil and its manufacturing method.

As a result of intensive studies to achieve the above object, the present inventors have cast-cured a coil component in which a primary coil and a secondary coil are wound around a magnetic core with a thermosetting resin composition, Furthermore, the present invention was completed by coating the outer layer with a resin layer.
That is, the present invention provides the following high voltage coil and method for manufacturing the same.

1. A high-voltage coil in which a thermosetting resin composition for casting is cast-cured on a coil component in which a primary coil and a secondary coil are wound around a magnetic core, and the cast-cured coil component is made of a coating resin. A high voltage coil characterized by being coated.
2. 2. The high voltage coil according to 1 above, wherein the coating resin is a thermosetting resin or a thermoplastic resin, and the bending elastic modulus after curing of the coating resin is 500 to 5000 MPa.
3. 3. The high voltage coil as described in 2 above, wherein the coating resin is an epoxy / amine coating resin.
4). The casting thermosetting resin composition comprises (A) an epoxy resin, (B) silica powder, (C) a curing agent and (D) a curing accelerator; and
Content of the said (B) component is 50-75 mass% of the whole resin composition,
In the component (B), the content of particles having a particle size of less than 1 μm is less than 0.1% by mass and the spherical silica powder having a volume average particle size of 10 to 30 μm is contained in an amount of 25 to 85% by mass,
4. The high voltage coil according to any one of the above 1 to 3, wherein the fibrous content is 1% by mass or less of the entire thermosetting resin composition for casting.
5. 5. The high voltage coil according to 4 above, wherein the casting thermosetting resin composition further comprises (E) rubber particles.
6). 6. The high-voltage coil according to 4 or 5 above, wherein the casting thermosetting resin composition contains 10 to 50% by mass of an alicyclic epoxy resin in the component (A).
7). The high voltage coil according to any one of the above 1 to 6, wherein the bending elastic modulus after curing of the thermosetting resin composition for casting is 6500 to 16000 MPa.
8). Including cast-curing a thermosetting resin composition for casting on a coil component in which a primary coil and a secondary coil are wound around a magnetic core, and coating the cast-cured coil component with a coating resin. 8. The method for producing a high voltage coil according to any one of 1 to 7 above.

  According to the present invention, a high voltage coil that can be manufactured at low cost and with high productivity while having high reliability and a method for manufacturing the same, and a note that is suitable for the high voltage coil and the manufacturing thereof. A thermosetting resin composition for forming can be provided.

Hereinafter, the present invention will be described in detail.
In the high voltage coil of the present invention, a casting thermosetting resin composition is cast-cured on a coil portion in which a primary coil and a secondary coil are wound around a magnetic core, and the cast-cured coil component is obtained. It is coated with a coating resin.

[Cooling resin composition for casting]
Although there is no restriction | limiting in particular as a thermosetting resin composition for casting in this invention, The epoxy resin composition for casting is preferable. In this specification, the casting epoxy resin composition will be described as an example.
First, the components (A) to (E) used in the casting epoxy resin composition will be described.

(A) Epoxy resin As the epoxy resin of component (A) used in the present invention, any resin having two or more epoxy groups in one molecule is generally used without being limited by molecular structure, molecular weight, etc. Can be widely used. Specifically, phenols such as phenol novolac type epoxy resin and cresol novolac type epoxy resin and epoxidized novolak resins of aldehydes; diglycidyl ethers such as bisphenol A, bisphenol F, bisphenol S, alkyl-substituted bisphenol, Glycidylamine-type epoxy resin obtained by reaction of polyamines such as diaminodiphenylmethane and isocyanuric acid with epichlorohydrin; linear aliphatic epoxy resin obtained by oxidizing olefinic bonds with peracids such as peracetic acid; by epoxidation of cyclohexane derivatives, etc. Examples thereof include alicyclic epoxy resins obtained; biphenyl type epoxy resins and the like. These epoxy resins may be used individually by 1 type, and 2 or more types may be mixed and used for them.

  In this invention, it is preferable to contain 10-50 mass% of alicyclic epoxy resins in (A) component. By using an alicyclic epoxy resin, the viscosity of the resin composition can be lowered and the glass transition point can be increased. Furthermore, since the alicyclic epoxy resin has a relatively high boiling point, it is difficult to volatilize during vacuum molding at a high temperature, and the vacuum moldability can be improved. (A) By making the ratio in a component into 10 mass% or more, the effect can fully be exhibited, and the reactivity of an alicyclic epoxy resin has a bad influence on a curing catalyst as it is 50 mass% or less. There is no possibility that the toughness of the cured product will be reduced and the brittleness will be reduced.

  As the component (A), in addition to those described above, for example, a liquid monoepoxy resin or a bromine-based epoxy resin can be used to impart flame retardancy. The liquid monoepoxy resin is preferably used as a combination component.

(B) Silica powder Examples of the silica powder of component (B) used in the present invention include fused silica, fused spherical silica, and crystalline silica, which may be pulverized.
In the present invention, the component (B) contains 25 to 85% by mass of spherical silica powder having a particle size of less than 0.1 μm and a volume average particle size of 10 to 30 μm. Preferably. When this condition is not satisfied, that is, when the content of the spherical silica powder in the component (B) is less than 25% by mass or exceeds 85% by mass, the elastic modulus of the cured product decreases. , Easy to break.

  (B) As a compounding quantity of the silica powder of a component, it is preferable to mix | blend (B) component 50-75 mass% of the whole resin composition, More preferably, it is 65-75 mass%. If the blending amount is 50% by mass or more of the entire resin composition, the mechanical strength of the cured product when the resin composition is cured can be made sufficient, and if it is 75% by mass or less, the resin An increase in the viscosity of the composition can be suppressed and the coil can be sufficiently impregnated, and the effects of the present invention can be obtained.

(C) Curing agent The curing agent of the component (C) used in the present invention can be used without particular limitation as long as it can react with the above-described (A) epoxy resin and be cured. it can. Specifically, acid anhydrides such as hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methyl hymic anhydride and derivatives thereof; phenol aralkyl resin, naphthol aralkyl resin Aralkyl type phenol resins such as: Novolak type phenol resins such as phenol novolak resin and cresol novolak resin; These modified resins such as epoxidized or butylated novolak type phenol resins such as dicyclopentadiene modified phenol resin, paraxylene modified phenol Examples thereof include phenol resin curing agents such as resins, triphenolalkane type phenol resins, and polyfunctional type phenol resins. In addition, amine complexes of Lewis acids such as dicyanamide, imidazole, aluminum chelate, and boron trifluoride can be used. These may be used individually by 1 type, and 2 or more types may be mixed and used for them. In the present invention, acid anhydrides are preferable, and methylhexahydrophthalic anhydride and methyltetrahydrophthalic anhydride are particularly preferable.

  (C) Although the compounding quantity of the hardening | curing agent of a component should just be the quantity which can harden (A) epoxy resin, Preferably it is the range of 80-120 mass parts with respect to 100 mass parts of (A) epoxy resin. Is preferred. When the blending amount is 80 parts by mass or more, the heat resistance is excellent, and when it is 120 parts by mass or less, the adhesiveness to the coil can be improved.

(D) Curing accelerator The curing accelerator of the component (D) used in the present invention is particularly limited as long as it has an action of promoting the reaction between the (A) epoxy resin and the (C) curing agent. Can be used without

  Specifically, 2-ethyl-4-methylimidazole, 2-heptadecylimidazole, 2-methylimidazole, 2-ethylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 4-methylimidazole, 4 -Ethylimidazole, 2-phenyl-4-hydroxymethylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, Imidazole compounds such as 2-phenyl-4,5-dihydroxymethylimidazole; triethylamine, triethylenediamine, benzyldimethylamine, α-methylbenzyldimethylamine, triethanolamine, dimethylaminoethanol, Tertiary amines such as-(dimethylaminomethyl) phenol and tris (dimethylaminomethyl) phenol; 1,8-diazabicyclo [5,4,0] undecene-7 (DBU), 1,5-diazabicyclo [4,3 , 0] nonene-5 and other diazabicycloalkenes and derivatives thereof; phosphines such as triethylphosphine, triphenylphosphine and diphenylphosphine; These may be used individually by 1 type, and 2 or more types may be mixed and used for them. In the present invention, tertiary amines such as imidazole compounds and DBU are preferred.

  The curing accelerator of the component (D) can be appropriately selected depending on the type of the curing agent (C), and the blending amount can be determined as appropriate.

(E) Rubber Particles The rubber particles of the component (E) used in the present invention are components that are blended as necessary in order to mainly impart crack resistance to the resin composition.
As the component (E), those having a core-shell structure are preferably used from the viewpoint of stability. Specific examples of commercially available products include Paraloid EXL2314 (trade name, manufactured by Kureha Chemical Industry Co., Ltd.), Staphyloid AC-3355, and Slaphyroid AC-3816 (both are trade names manufactured by Gantz Kasei Co., Ltd.). Can be mentioned. These may be used individually by 1 type, and may mix and use 2 or more types.

  The compounding amount of the rubber particles of the component (E) is preferably 0.1 to 10 parts by mass, more preferably 0.3 to 7 parts by mass with respect to 100 parts by mass of the (A) epoxy resin. . If the blending amount is 0.1 parts by mass or more, crack resistance can be sufficiently imparted, and if it is 10 parts by mass or less, the coil impregnation property is good.

Next, in addition to the components (A) to (E), various components that are blended in the casting epoxy resin composition as necessary will be described.
In the epoxy resin composition for casting of the present invention, one or more inorganic fillers other than (B) silica powder can be blended as necessary within a range not impairing the effects of the present invention. Examples of such inorganic fillers include alumina, zircon, talc, calcium silicate, calcium carbonate, titanium white, clay, bengara, silicon carbide, boron nitride, beryllia, zirconia, and the like. Examples include potassium acid, silicon carbide, and silicon nitride.

Further, in the field of casting epoxy resin compositions, reactive diluents such as alicyclic epoxy compounds, coupling agents, anti-settling agents, colorants such as carbon black, A foaming agent, antimony trioxide and the like can be blended.
However, for the purpose of the present invention, it is preferable that the fiber is not substantially contained so as to be 1% by mass or less of the entire resin composition. When the fiber content exceeds 1% by mass of the entire resin composition, the impregnation property to the coil is lowered, and the effect of the present invention cannot be obtained.

  The thermosetting resin composition for casting of the present invention preferably has a flexural modulus after curing of 6500 to 16000 MPa, more preferably 9000 to 13000 MPa. If the flexural modulus after curing is 6500 MPa or more, cracks will not occur when the mold is released, and if it is 16000 MPa or less, the toughness will be excellent and the moldability will be good.

  In preparing the casting thermosetting resin composition of the present invention as a casting material, a usual method can be used. That is, for example, when using an epoxy resin composition for casting, the main agent is obtained by sufficiently mixing (A) an epoxy resin with (B) silica powder and various components blended as necessary with a mixer or the like. Prepare ingredients. On the other hand, a curing agent component is prepared by sufficiently mixing (C) a curing agent, (D) a curing accelerator, and (E) rubber particles. The prepared main agent component and curing agent component can be prepared as a casting material by mixing them uniformly with a mixer or the like.

[Resin for coating]
The coating resin in the present invention may be either a thermosetting resin such as an epoxy resin, a phenol resin, an unsaturated polyester resin, or a polyimide resin, or a thermoplastic resin such as a fluororesin or a silicone resin. It is preferable that the elastic modulus is 500 to 5000 MPa and curing is performed at a low temperature of 20 to 50 ° C. If the flexural modulus is 500 MPa or more, no dent or the like is generated with respect to an impact from the outside, and if it is 5000 MPa or less, cracks do not occur. Particularly preferred are epoxy / amine-based coating agents, for example, trade name: TCG0295 manufactured by Kyocera Chemical Co., Ltd. is particularly preferred.

[Manufacturing method of high voltage coil]
As a manufacturing method of the high voltage coil in the present invention, using required coil components such as a magnetic core, a primary coil, and a secondary coil,
For example, first, a coil part is assembled by winding a primary coil and a secondary coil around a magnetic core. After the coil component is placed in the casting mold, the casting thermosetting resin composition is cast into the mold under vacuum and cured by heating.
In addition, it is preferable to use a casting mold having a resin liquid reservoir for temporarily retaining the injected resin at the connection portion from the gate to the runner and having a vent at the end. The casting conditions are preferably a resin temperature of 120 to 150 ° C. at injection, a resin viscosity of 0.1 to 2 Pa · s, and a resin filling speed of 5 to 20 cm ³ / sec per part.
Next, the high voltage coil of the present invention can be manufactured by coating the outer layer of the cast-cured coil component with the coating resin.
The coating of the coil component with the coating resin is not particularly limited as long as it can be coated, such as a dipping method, a spray method, or a film covering method. If the thickness of a coating layer is 1-500 micrometers, it can be set as the high voltage coil excellent in impact resistance.

  EXAMPLES Next, although an Example and a comparative example demonstrate this invention in detail, this invention is not limited at all by these.

In the following Examples 1 to 9, Comparative Example 1 and Reference Example 1, each component used is as follows.
(A) Epoxy resin EP4100E (trade name, manufactured by ADEKA Corporation) as a bisphenol A diglycidyl ether type liquid epoxy resin, ERL 4221 (trade name, manufactured by Dow Chemical Co., Ltd.) as an alicyclic epoxy resin
(B) Silica powder Fulexex RD-8 (ground silica, average particle size 15 μm, trade name, manufactured by Tatsumori Co., Ltd.), Fulex® MSR-15 (spherical silica, average particle size 15 μm, manufactured by Tatsumori Co., Ltd.) Name), FB-5D (spherical silica, average particle size 6 μm, product name, manufactured by Denki Kagaku Kogyo Co., Ltd.)

(C) Hardener HN2000 (trade name, manufactured by Hitachi Chemical Co., Ltd.) as an acid anhydride
(D) Curing accelerator Kao Raiser No. as a curing accelerator. 20 (trade name, manufactured by Kao Corporation), Adeka Hardener EHC-30 (trade name, manufactured by ADEKA Corporation)
(E) Rubber particles Paraloid EXL2314 (trade name, manufactured by Kureha Chemical Industry Co., Ltd.) as rubber particles
(Optional component)
TSA720 (trade name, manufactured by GE Toshiba Silicone Co., Ltd.) as an antifoaming agent, and A-187 (trade name, manufactured by Nippon Unicar Co., Ltd.) as a silane coupling agent

Examples 1 to 9, Comparative Example 1 and Reference Example 1
In Examples 1 to 9, Comparative Example 1 and Reference Example 1, the above components were blended in the proportions shown in Table 1 and performed as shown in (1) and (2) below.
(1) (A) Epoxy resin, (B) Silica powder and optional components were vacuum kneaded for 1 hour to prepare a main component. Further, (C) a curing agent, (D) a curing accelerator, and (E) rubber particles were mixed to prepare a curing agent component. The prepared main component and curing agent component were uniformly mixed to obtain a thermosetting resin composition for casting.
(2) Next, a coil component (bobbin diameter 18 mm, winding diameter 45 μm, number of turns 15000) in which coil components such as a magnetic core, a primary coil, and a secondary coil are assembled is placed in a casting mold, The thermosetting resin composition for casting was cast into a mold under vacuum and impregnated into coil parts. After being cured by heating at 150 ° C. for 10 minutes, it was removed from the mold and further cured at 150 ° C. for 1 hour. Thereafter, an epoxy coating agent as a coating resin was dip coated on the surface of the cast-cured coil component to produce a coil having a coating thickness of 10 μm.

The following were used as the epoxy coating agent that is a coating resin.
TCG0295 [(Epoxy / Amine) manufactured by Kyocera Chemical Co., Ltd. Trade name, flexural modulus (25 ° C.): 620 MPa, surface treatment condition: 25 ° C./24 hours], TCG 2045 [(Epoxy / acid anhydride) Kyocera Chemical Co., Ltd. Product name, flexural modulus (25 ° C.): 300 MPa, surface treatment conditions: 160 ° C./1 hour]

[Characteristic evaluation]
About the thing which made the thermosetting resin composition for casting of Examples 1-9, the comparative example 1, and the reference example 1 into the hardened | cured material, and the obtained coil, the characteristic was evaluated with the following method. The obtained results are shown in Table 1 together with the composition of the thermosetting resin composition for casting.
Regarding the evaluation of the characteristics of the coil, Comparative Example 1 was evaluated without being coated with a coating resin, and Reference Example 1 was evaluated by producing a coil using a polypropylene case (case outer diameter: 23 mm).

(1) Bending elastic modulus and bending strength of cured product After a thermosetting resin composition for casting was heated and cured at 150 ° C. for 1.5 hours to prepare a test piece, this test piece was in accordance with JIS C 2105. Accordingly, the measurement was performed at 25 ° C.
(2) Glass transition point of cured product After the thermosetting resin composition for casting was cured by heating at 150 ° C. for 1.5 hours to prepare a test piece, the test piece was increased to 250 ° C. at 10 ° C./min. The temperature was raised and measured using a TMA (thermomechanical analyzer).
(3) Coil impregnation property, surface appearance, surface strength Coil impregnation property and surface appearance were evaluated by visually observing the cut surface of the coil and the presence or absence of voids on the surface appearance. The coil was dropped from a height of 1 m and 3 m, and the surface strength was evaluated by visually observing the presence of cracks and dents on the surface.

  From Table 1, the high voltage coil of the present invention uses a thermosetting resin composition for casting with excellent properties of a cured product, and has the same surface strength as the coil of Reference Example 1 using a polypropylene case. I understand that.

  The high voltage coil of the present invention is particularly useful as an ignition coil because it can be manufactured at lower cost and with higher productivity than the conventional one and has high reliability.

Claims (8)

  A high-voltage coil in which a thermosetting resin composition for casting is cast-cured on a coil component in which a primary coil and a secondary coil are wound around a magnetic core, and the cast-cured coil component is made of a coating resin. A high voltage coil characterized by being coated.   2. The high voltage coil according to claim 1, wherein the coating resin is a thermosetting resin or a thermoplastic resin, and the bending elastic modulus after curing of the coating resin is 500 to 5000 MPa.   3. The high voltage coil according to claim 2, wherein the coating resin is an epoxy / amine coating resin. The casting thermosetting resin composition comprises (A) an epoxy resin, (B) silica powder, (C) a curing agent and (D) a curing accelerator; and
Content of the said (B) component is 50-75 mass% of the whole resin composition,
In the component (B), the content of particles having a particle size of less than 1 μm is less than 0.1% by mass and the spherical silica powder having a volume average particle size of 10 to 30 μm is contained in an amount of 25 to 85% by mass,
The high-voltage coil according to any one of claims 1 to 3, wherein the fibrous content is 1% by mass or less of the entire thermosetting resin composition for casting.   The high-voltage coil according to claim 4, wherein the casting thermosetting resin composition further comprises (E) rubber particles.   The high-voltage coil according to claim 4 or 5, wherein the thermosetting resin composition for casting contains 10 to 50% by mass of an alicyclic epoxy resin in the component (A).   The high-voltage coil according to any one of claims 1 to 6, wherein a bending elastic modulus after curing of the thermosetting resin composition for casting is 6500 to 16000 MPa.   Including cast-curing a thermosetting resin composition for casting on a coil component in which a primary coil and a secondary coil are wound around a magnetic core, and coating the cast-cured coil component with a coating resin. The manufacturing method of the high voltage coil in any one of Claims 1-7.