JP2006222280A - Method for manufacturing magnetic sheet - Google Patents
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- JP2006222280A JP2006222280A JP2005034488A JP2005034488A JP2006222280A JP 2006222280 A JP2006222280 A JP 2006222280A JP 2005034488 A JP2005034488 A JP 2005034488A JP 2005034488 A JP2005034488 A JP 2005034488A JP 2006222280 A JP2006222280 A JP 2006222280A
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Abstract
Description
本発明は、樹脂に磁性フィラーを充填してなる磁性シートの製造方法に関し、詳しくは、磁性フィラーを樹脂及び溶剤と混練し、基材上に塗布して乾燥させることによってシート状に成形する磁性シートの製造方法に関する。 The present invention relates to a method for producing a magnetic sheet obtained by filling a resin with a magnetic filler. Specifically, the magnetic filler is kneaded with a resin and a solvent, applied onto a substrate, and dried to form a sheet. The present invention relates to a sheet manufacturing method.
従来より、扁平形状を有する磁性フィラーを樹脂及び溶剤中に分散させ、ＰＥＴ等の基材上に塗布して乾燥することによって薄膜状の磁性シートを製造することが提案されている（例えば、特許文献１参照）。このようにして製造された磁性シートは、電子機器のＩＣやケーブルから発生する電磁波ノイズ対策として、携帯電話等の小型機器にも使用することができる。
電磁波ノイズ対策における効果を表す指標として、透磁率特性が用いられるが、従来は、磁性フィラーの充填量を上げれば上げるほど透磁率特性は向上するものと考えられていた。そこで、磁性フィラーの充填量は、シート化し易い充填量の上限近傍に設定するのが一般的であった。また、従来は固形分量（すなわち、溶剤，磁性フィラー，樹脂を含む乾燥前の磁性シート全体に対する磁性フィラー及び樹脂の量）は、透磁率特性に影響を与えないと考えられており、基材への塗布が容易な量に設定されていた。 Permeability characteristics are used as an index representing the effect of electromagnetic wave noise countermeasures. Conventionally, it has been considered that the permeability characteristics improve as the filling amount of the magnetic filler increases. Therefore, the filling amount of the magnetic filler is generally set in the vicinity of the upper limit of the filling amount that is easily formed into a sheet. Conventionally, the solid content (that is, the amount of the magnetic filler and the resin relative to the entire magnetic sheet before drying including the solvent, the magnetic filler, and the resin) is considered to have no influence on the magnetic permeability characteristics. The amount was set to an amount easy to apply.
このため、従来の製造方法で得られる磁性シートには、透磁率特性の向上において限界があった。そこで、本発明は、磁性フィラーを樹脂及び溶剤と混練し、基材上に塗布して乾燥させることによってシート状に成形する磁性シートの製造方法において、製造方法の改良によって一層良好な透磁率特性を有する磁性シートを提供することを目的としてなされた。 For this reason, the magnetic sheet obtained by the conventional manufacturing method has a limit in improving the magnetic permeability characteristics. Therefore, the present invention provides a magnetic sheet that is kneaded with a resin and a solvent, coated on a substrate and dried to form a sheet, and the magnetic property is further improved by improving the manufacturing method. It was made for the purpose of providing the magnetic sheet which has.
上記目的を達するためになされた本発明は、磁性フィラーを樹脂及び溶剤と混練し、基材上に塗布して乾燥させることによってシート状に成形する磁性シートの製造方法であって、上記磁性フィラーは、アスペクト比が３以上の扁平形状を有し、その磁性フィラーの充填量が乾燥後の磁性シート全体の７４〜７９ｗｔ％であり、上記混練終了時における固形分量が４０〜４７ｗｔ％であることを特徴としている。 The present invention made to achieve the above object is a method for producing a magnetic sheet, in which a magnetic filler is kneaded with a resin and a solvent, coated on a substrate and dried to form a sheet, and the magnetic filler Has a flat shape with an aspect ratio of 3 or more, the filling amount of the magnetic filler is 74 to 79 wt% of the whole magnetic sheet after drying, and the solid content at the end of the kneading is 40 to 47 wt% It is characterized by.
本願出願人は、アスペクト比（平均粒径を平均厚さで除した値）が３以上の扁平形状を有する磁性フィラーを樹脂及び溶剤と混練し、基材上に塗布して乾燥させることによってシート状に成形し、磁性シートを得る実験を種々繰り返した。その結果、磁性フィラーの充填量が乾燥後の磁性シート全体の７９ｗｔ％程度までならば、充填量を上げれば上げるほど透磁率特性は向上するが、それ以上充填量を上げると却って透磁率特性が低下することを発見した。これは、磁性フィラーを充填し過ぎると、磁性シート内における磁性フィラーの配向が乱れるためと考えられる。 The applicant of the present application kneaded a magnetic filler having a flat shape with an aspect ratio (a value obtained by dividing the average particle diameter by the average thickness) of 3 or more with a resin and a solvent, applied onto a substrate and dried. Various experiments were repeated to obtain a magnetic sheet. As a result, if the filling amount of the magnetic filler is up to about 79 wt% of the entire magnetic sheet after drying, the permeability characteristic is improved as the filling amount is increased. However, if the filling amount is further increased, the permeability characteristic is reversed. I found it to decline. This is probably because the orientation of the magnetic filler in the magnetic sheet is disturbed if the magnetic filler is excessively filled.
また、上記固形分量が３９ｗｔ％以下では透磁率特性が低下し、固形分量が４８ｗｔ％以上では混練終了後の材料がぼそぼそになってシートの成形性が低下し、生産性も低下することが分かった。そこで、本発明では、上記充填量を７４〜７９ｗｔ％とし、固形分量を４０〜４７ｗｔ％としている。 Further, it is understood that when the solid content is 39 wt% or less, the magnetic permeability characteristics are lowered, and when the solid content is 48 wt% or more, the material after kneading is loosened, the sheet formability is lowered, and the productivity is also lowered. It was. Therefore, in the present invention, the filling amount is 74 to 79 wt%, and the solid content is 40 to 47 wt%.
このため、本発明では、高い透磁率特性を有し、シートとしての状態も優れた磁性シートを効率的に製造することができる。また、本発明では、磁性フィラーを過充填しないことによるコスト削減や軽量化も可能になる。更に、本発明では、シート成形後に圧延・プレス等の特別な配向処理を加えなくても、磁性フィラーが良好に配向した磁性シートを従来のコーター等の装置によって容易に製造することができる。 For this reason, in this invention, it can manufacture efficiently the magnetic sheet which has the high magnetic permeability characteristic and was excellent in the state as a sheet | seat. Moreover, in this invention, the cost reduction and weight reduction by not overfilling a magnetic filler are also attained. Furthermore, in the present invention, a magnetic sheet in which the magnetic filler is well oriented can be easily produced by a conventional apparatus such as a coater without adding a special orientation treatment such as rolling or pressing after the sheet is formed.
なお、本発明で使用する磁性フィラーとしては、アスペクト比が３以上のものであれば種々のものが使用できるが、上記扁平粒子が、密度が６〜９ｇ／ｃｍ3 であり、粒度分布がＤ５０で１０〜３０μｍである場合、透磁率特性を一層向上させることができる。また、本発明で使用する樹脂としても、種々のものが使用できるが、上記樹脂が塩素化ポリエチレンである場合、透磁率特性及び生産性を一層向上させることができる。 As the magnetic filler used in the present invention, various types can be used as long as the aspect ratio is 3 or more, but the flat particles have a density of 6 to 9 g / cm 3 and a particle size distribution of D50. In the case of 10 to 30 μm, the magnetic permeability characteristics can be further improved. In addition, various resins can be used as the resin used in the present invention, but when the resin is chlorinated polyethylene, the magnetic permeability characteristics and productivity can be further improved.
次に、本発明の実施の形態を、図面と共に説明する。先ず、本願出願人は、次のような各工程を経て磁性シートを作成した。
（１）磁性フィラーの作成工程
Ｓｉ：８〜２０ｗｔ％、Ｃｒ：０．５〜１０ｗｔ％、残部Ｆｅ及び不純物（微量添加物を含む）からなる合金を作成し、それに粉砕及び扁平化処理を施すことにより、密度が６〜９ｇ／ｃｍ3 、粒度分布がＤ５０で１０〜３０μｍ、アスペクト比が３以上の扁平粒子を磁性フィラー１（図３参照）として作成した。
（２）混練工程
この磁性フィラー１を、塩素化ポリエチレンなど密度１〜１．５ｇ／ｃｍ3 のもの、或いはアクリル、ウレタンなどの樹脂２（図３参照）、並びに、トルエンなどの溶剤若しくは水系溶剤と混練した。この混練には、真空脱泡ミキサー等の機械を用いる。
（３）塗布・乾燥工程
続いて、上記混練工程によって得られた材料３を次のように一般的なコーターにてシート状に成形した。すなわち、図１に示すように、ドラム４から繰り出されるＰＥＴフィルム５（基材に相当）の上に材料タンク６から上記混練工程によって得られた材料３を投入し、更にＰＥＴフィルム５を搬送する。その下流側にはロール７が配設され、ＰＥＴフィルム５に積載された材料３がこのロール７を通過することにより、一定の厚さのシート状に成形される。ロール７を通過した材料３は、続いて乾燥機９により溶剤を揮発・乾燥された後、磁性シート１０としてドラム１１に巻回される。
Next, embodiments of the present invention will be described with reference to the drawings. First, the applicant of the present application created a magnetic sheet through the following steps.
(1) Magnetic filler production process Si: 8-20 wt%, Cr: 0.5-10 wt%, an alloy composed of the balance Fe and impurities (including a trace additive) is produced, and pulverized and flattened. Accordingly, flat particles having a density of 6 to 9 g / cm 3 , a particle size distribution of D50 of 10 to 30 μm, and an aspect ratio of 3 or more were prepared as the magnetic filler 1 (see FIG. 3).
(2) Kneading step The magnetic filler 1 is made of chlorinated polyethylene having a density of 1 to 1.5 g / cm 3 , or resin 2 such as acrylic or urethane (see FIG. 3), and a solvent such as toluene or an aqueous solvent. And kneaded. For this kneading, a machine such as a vacuum defoaming mixer is used.
(3) Coating / Drying Step Subsequently, the material 3 obtained by the kneading step was formed into a sheet shape with a general coater as follows. That is, as shown in FIG. 1, the material 3 obtained by the kneading process is charged from the material tank 6 onto the PET film 5 (corresponding to the base material) fed out from the drum 4, and the PET film 5 is further conveyed. . A roll 7 is disposed on the downstream side, and the material 3 loaded on the PET film 5 passes through the roll 7 to be formed into a sheet having a certain thickness. The material 3 that has passed through the roll 7 is then volatilized and dried by a dryer 9 and then wound around a drum 11 as a magnetic sheet 10.
次に、上記製造工程において、磁性フィラー１の充填量を乾燥後の磁性シート１０全体の３４〜８０ｗｔ％の範囲で変化させて、磁性シート１０の透磁率を比較した。なお、実験では、樹脂２として塩素化ポリエチレンを使用して厚さ０．１ｍｍの磁性シート１０を成形した。また、アジレントテクノロジー製「Ｅ４９９１Ａ（商品名）」を用いて、３０ＭＨｚと１００ＭＨｚとの２つの周波数で透磁率を測定した。結果を図２に示す。図２に示すように、磁性フィラー１の充填量が乾燥後の磁性シート全体の７９ｗｔ％程度までの範囲では、充填量を上げれば上げるほど透磁率は向上するが、それ以上充填量を上げると却って透磁率が低下した。 Next, in the said manufacturing process, the filling amount of the magnetic filler 1 was changed in the range of 34-80 wt% of the magnetic sheet 10 whole after drying, and the magnetic permeability of the magnetic sheet 10 was compared. In the experiment, a magnetic sheet 10 having a thickness of 0.1 mm was formed using chlorinated polyethylene as the resin 2. Moreover, the magnetic permeability was measured at two frequencies of 30 MHz and 100 MHz using “E4991A (trade name)” manufactured by Agilent Technologies. The results are shown in FIG. As shown in FIG. 2, in the range where the filling amount of the magnetic filler 1 is up to about 79 wt% of the entire magnetic sheet after drying, the permeability increases as the filling amount increases, but when the filling amount is increased further, as shown in FIG. On the contrary, the permeability decreased.
このメカニズムは更に検証の余地があるが、磁性フィラー１を充填し過ぎると磁性シート１０内における磁性フィラー１の配向が乱れるためと考えられる。すなわち、磁性フィラー１の充填量が７９ｗｔ％以下の場合は、図３（Ａ）に例示するように、磁性フィラー１は磁性シート１０の成形方向に沿って規則的に配向するが、充填量が８０ｗｔ％以上となると、図３（Ｂ）に例示するように配向が乱れるのである。 Although there is room for further verification of this mechanism, it is considered that the orientation of the magnetic filler 1 in the magnetic sheet 10 is disturbed if the magnetic filler 1 is overfilled. That is, when the filling amount of the magnetic filler 1 is 79 wt% or less, the magnetic filler 1 is regularly oriented along the forming direction of the magnetic sheet 10 as illustrated in FIG. When it is 80 wt% or more, the orientation is disturbed as illustrated in FIG.
また、材料３の固形分量を３０〜５０ｗｔ％の範囲で変化させて透磁率を比較した結果を、図４に示す。図４に示すように、上記固形分量が３９ｗｔ％以下では透磁率が低下してしまう。また、固形分量を４８ｗｔ％以上とすると、材料３はぼそぼそになってシートの成形性が低下し、生産性も低下することが分かった。 Moreover, the result of having changed the solid content amount of the material 3 in the range of 30-50 wt%, and comparing the magnetic permeability is shown in FIG. As shown in FIG. 4, when the solid content is 39 wt% or less, the magnetic permeability decreases. Further, it was found that when the solid content was 48 wt% or more, the material 3 was loose and the formability of the sheet was lowered and the productivity was also lowered.
そこで、本実施の形態では、上記充填量を７４〜７９ｗｔ％とし、固形分量を４０〜４７ｗｔ％とした。このため、本実施の形態では、高い透磁率を有し、シートとしての状態も優れた磁性シート１０を効率的に製造することができる。また、本実施の形態では、磁性フィラー１を過充填しないことによるコスト削減や軽量化も可能になる。更に、本実施の形態では、シート成形後に圧延・プレス等の特別な配向処理を加えなくても、磁性フィラー１が良好に配向した磁性シート１０を従来のコーター等の装置によって容易に製造することができる。 Therefore, in the present embodiment, the filling amount is 74 to 79 wt%, and the solid content is 40 to 47 wt%. For this reason, in this Embodiment, the magnetic sheet 10 which has a high magnetic permeability and was excellent in the state as a sheet | seat can be manufactured efficiently. Moreover, in this Embodiment, the cost reduction and weight reduction by not overfilling the magnetic filler 1 are also attained. Furthermore, in this embodiment, the magnetic sheet 10 in which the magnetic filler 1 is well oriented can be easily manufactured by a conventional apparatus such as a coater without adding a special orientation treatment such as rolling or pressing after the sheet is formed. Can do.
なお、本発明は上記実施の形態に何ら限定されるものではなく、本発明の要旨を逸脱しない範囲で種々の形態で実施することができる。例えば、磁性フィラーは上記のものに限定される訳ではなく、Ｆｅ，Ｓｉ，Ｃｒの配合を変えてもよく、その他の磁性フィラーを使用してもよく、アスペクト比が３以上のものであれば種々のものが使用できる。 In addition, this invention is not limited to the said embodiment at all, It can implement with a various form in the range which does not deviate from the summary of this invention. For example, the magnetic filler is not limited to the above, and the composition of Fe, Si, Cr may be changed, other magnetic fillers may be used, and the aspect ratio is 3 or more. Various things can be used.
１…磁性フィラー ２…樹脂 ３…材料 ５…ＰＥＴフィルム
６…材料タンク ７…ロール ９…乾燥機 １０…磁性シート
DESCRIPTION OF SYMBOLS 1 ... Magnetic filler 2 ... Resin 3 ... Material 5 ... PET film 6 ... Material tank 7 ... Roll 9 ... Dryer 10 ... Magnetic sheet
Claims (3)
上記磁性フィラーは、アスペクト比が３以上の扁平形状を有し、その磁性フィラーの充填量が乾燥後の磁性シート全体の７４〜７９ｗｔ％であり、
上記混練終了時における固形分量が４０〜４７ｗｔ％であることを特徴とする磁性シートの製造方法。 A magnetic sheet is kneaded with a resin and a solvent, applied to a substrate and dried to form a magnetic sheet,
The magnetic filler has a flat shape with an aspect ratio of 3 or more, and the filling amount of the magnetic filler is 74 to 79 wt% of the whole magnetic sheet after drying,
A method for producing a magnetic sheet, wherein the solid content at the end of the kneading is 40 to 47 wt%.
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| JP2005034488A JP2006222280A (en) | 2005-02-10 | 2005-02-10 | Method for manufacturing magnetic sheet |
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| JP2005034488A JP2006222280A (en) | 2005-02-10 | 2005-02-10 | Method for manufacturing magnetic sheet |
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2000244171A (en) * | 1998-12-22 | 2000-09-08 | Tokin Corp | Method of producing magnetic sheet |
| JP2001044687A (en) * | 1999-07-29 | 2001-02-16 | Nitto Denko Corp | Wave absorber and its manufacture |
| JP2003324299A (en) * | 2002-05-01 | 2003-11-14 | Daido Steel Co Ltd | Halogen-free flame retardant electromagnetic wave suppressing sheet and its manufacturing method |
| JP2004017547A (en) * | 2002-06-19 | 2004-01-22 | Sumitomo Electric Ind Ltd | Resin laminate and manufacturing method therefor |
| JP2004140335A (en) * | 2002-08-19 | 2004-05-13 | Sumitomo Electric Ind Ltd | Electromagnetic wave absorbing material |
-
2005
- 2005-02-10 JP JP2005034488A patent/JP2006222280A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2000244171A (en) * | 1998-12-22 | 2000-09-08 | Tokin Corp | Method of producing magnetic sheet |
| JP2001044687A (en) * | 1999-07-29 | 2001-02-16 | Nitto Denko Corp | Wave absorber and its manufacture |
| JP2003324299A (en) * | 2002-05-01 | 2003-11-14 | Daido Steel Co Ltd | Halogen-free flame retardant electromagnetic wave suppressing sheet and its manufacturing method |
| JP2004017547A (en) * | 2002-06-19 | 2004-01-22 | Sumitomo Electric Ind Ltd | Resin laminate and manufacturing method therefor |
| JP2004140335A (en) * | 2002-08-19 | 2004-05-13 | Sumitomo Electric Ind Ltd | Electromagnetic wave absorbing material |
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