JPS6216237A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve dispersibility and electromagnetic conversion characteristic and to obtain excellent acid resistance by preliminarily coating the surface of metallic magnetic powder to be incorporated into a magnetic layer with a specific compd. CONSTITUTION:The surface of the magnetic metallic powder to be dispersed into a magnetic binder resin provided on a non-magnetic substrate is preliminari ly coated with the compd. expressed by the formula (R1, R2 are perfluoroalkyl of 4-18C). The perfluoroalkyl group is directed toward the outside and the dense adsorptive layer structure is formed on the particle surface of the mag netic metallic powder by using the phosphate of the perfluoroalkyl of such compd., by which the surface energy of the metallic particles is decreased. The dispersion effect is thus improved and since the adsorptive layer is hydro phobic, the intrusion of water to the metallic surface is prevented and the oxida tion resistance is improved. The gloss of the magnetic layer is thereby improved and the medium having high output and high S/N ratio in the high band is obtd. Such medium is used as a magnetic tape and magnetic disk for video apparatus and computers.

Description

【発明の詳細な説明】 産業上の利用分野 本発明はビデオ機器、コンピューター等に用いる磁気記
録テープ、および磁気ディスク等の磁気記録媒体に関す
るものである。DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to magnetic recording media such as magnetic recording tapes and magnetic disks used in video equipment, computers, and the like.

従来の技術 近年、磁気記録装置の小型、軽量化に伴ない磁気記録媒
体にもますます高密度化が要望されている０また一方で
は使用環境の多様化に伴ない耐環境特性のすぐれたもの
が要望されている。Conventional technology In recent years, as magnetic recording devices have become smaller and lighter, there has been a demand for higher density magnetic recording media.On the other hand, as the environments in which they are used have become more diverse, there has been a demand for products with superior environmental resistance. is requested.

高密度化に対応して、保磁力が大きく、飽和磁化量の大
きい鉄を主成分とした金属磁性粉末を使用した磁気記録
媒体が８ｍｍビデオやビデオフロッピーなどに実用化さ
れて来た。In response to higher density, magnetic recording media using metal magnetic powders mainly composed of iron, which have a large coercive force and a large amount of saturation magnetization, have been put into practical use in 8 mm videos, video floppies, and the like.

これらの磁気記録媒体においては、高域での高出力、高
Ｓ／Ｎ比の改善などの要望のもとに、これらに使用され
る磁性粉はさらに微細化の方向に進んでいる。しかし、
磁性粉がより微粒子になるに従って、粒子の凝集が起こ
りやすくなり、結合剤樹脂中に均一な分散ができず期待
される感度特性や、　°Ｓ／Ｎが出ない欠点が生じてく
る。また一方、金属磁性粉末が微細になるに従って、酸
素、水の存在のもとて酸化を受けやすくなり、酸化の進
行とともに飽和磁化量（σＳ）などの磁気特性が経時的
に低下し、信頼性に問題が生じて来る。In these magnetic recording media, the magnetic powder used in these media is progressing in the direction of further miniaturization in response to demands for high output at high frequencies, high S/N ratio improvement, and the like. but,
As the magnetic powder becomes finer, it becomes more likely that the particles will agglomerate, and the particles will not be uniformly dispersed in the binder resin, resulting in the disadvantage that the expected sensitivity characteristics and °S/N ratio will not be achieved. On the other hand, as metal magnetic powder becomes finer, it becomes more susceptible to oxidation in the presence of oxygen and water, and as oxidation progresses, magnetic properties such as saturation magnetization (σS) deteriorate over time, reducing reliability. A problem arises.

このような観点から従来より、分散性の向上に関しては
種々の観点から研究されており、特殊な界面活性剤の提
案または磁性粉表面を特殊な化合物で表面処理する提案
などがある０また耐酸化性に対しては、加熱還元して得
られた直後の金属磁性粉末をトルエンなどの有機溶媒中
に浸漬し、徐々に粒子表面を酸化させて、表面に酸化被
膜を形成させ、耐酸化性の向上を図ったり、特殊な物質
で粒子表面を被覆処理して、耐酸化性１分散性を改善す
ることが提案されている。From this point of view, improvements in dispersibility have been studied from various viewpoints, including proposals for special surfactants and surface treatment of magnetic powder surfaces with special compounds. In order to improve the oxidation resistance, metal magnetic powder immediately after heat reduction is immersed in an organic solvent such as toluene, and the particle surface is gradually oxidized to form an oxide film on the surface. It has been proposed to improve oxidation resistance and dispersibility by coating the particle surface with a special substance.

発明が解決しようとする問題点 しかしながら、磁性物のＢＥＴ表面積が５０ｍ”／ｇ　
ｒ以上の微細な粒子になると１．これらの方法でも、ま
だ充分に満足できる状態でなく、問題が残されている０ 本発明の目的は、金属磁性粉の分散性を向上させ、電磁
変換特性がすぐれていると同時に、耐酸化性の改善され
た磁気記録媒体を提供することである。Problems to be Solved by the Invention However, the BET surface area of the magnetic material is 50 m''/g.
When it comes to fine particles larger than r, 1. Even with these methods, problems are still unsatisfactory.The purpose of the present invention is to improve the dispersibility of metal magnetic powder, to provide excellent electromagnetic conversion characteristics, and at the same time, to provide oxidation resistance. An object of the present invention is to provide an improved magnetic recording medium.

）　　　　　　問題点を解決するための手段本発明の磁
気記録媒体は、非磁性の支持体上に、金属磁性粉末を結
合剤樹脂中に分散させてなる磁性層を形成することによ
り構成され、かつ前記金属磁性粉末があらかじめ で示される化合物（但しＲ，、Ｒ２は炭素数が４〜１８
個のパーフロロアルキル基）で表面被覆されたものであ
る。) Means for Solving the Problems The magnetic recording medium of the present invention is constructed by forming a magnetic layer on a non-magnetic support by dispersing metal magnetic powder in a binder resin, and The metal magnetic powder is a compound represented by (however, R,, R2 has 4 to 18 carbon atoms)
The surface is coated with perfluoroalkyl groups).

作用 本発明の特徴とする前記化合物のパーフロロアルキルの
リン酸エステルは金属磁性粉末の粒子表面にパーフロロ
アルキル基を外側に向けて、緻密な吸着層構造を形成し
、金属粒子表面の表面エネルギーを著しく低下させる機
能を有する。これによって分散効果を著しく高める作用
をするものであり、またその吸着層が極めて疎水性であ
り、金属表面への水の浸入を防ぐことが耐酸化性を著し
く高める作用をするものである。従って本発明では、前
記化合物のパーフロロアルキルのリン酸エステルが金属
磁性粉の粒子表面に緻密な吸着層を形成させることが第
１要件である。Effect The perfluoroalkyl phosphate ester of the above compound, which is a feature of the present invention, forms a dense adsorption layer structure on the particle surface of the metal magnetic powder with the perfluoroalkyl group facing outward, thereby reducing the surface energy of the metal particle surface. It has the ability to significantly reduce This significantly enhances the dispersion effect, and the adsorption layer is extremely hydrophobic, preventing water from penetrating into the metal surface, thereby significantly increasing the oxidation resistance. Therefore, in the present invention, the first requirement is that the perfluoroalkyl phosphate ester of the compound forms a dense adsorption layer on the particle surface of the metal magnetic powder.

本発明によれば、前記化合物のパーフロロアルキル基の
炭素数によって分散効果、耐酸化性が大きく左右される
。ノ４−フロロアルキル鎖の長い方が分散効果がよくな
る傾向にあるが、炭素数が１８個以上になると、金属粉
への吸着力が低下し、緻密な吸着層が形成されず、耐酸
化性の効果が低下する。分酸性、耐酸化性の両面から好
ましいパーフロロアルキル鎖の炭素数は４から１８個で
ある。According to the present invention, the dispersion effect and oxidation resistance are greatly influenced by the number of carbon atoms in the perfluoroalkyl group of the compound. The longer the 4-fluoroalkyl chain, the better the dispersion effect, but when the number of carbon atoms exceeds 18, the adsorption power to metal powder decreases, a dense adsorption layer is not formed, and the oxidation resistance decreases. becomes less effective. The number of carbon atoms in the perfluoroalkyl chain is preferably 4 to 18 from the viewpoint of both acid separation and oxidation resistance.

本発明において、前記化合物のパーフロロアルキルのリ
ン酸エステルを磁性粉に吸着させて表面被覆し、磁性層
中に含ませる方法としては、大別して２通シのものがあ
る。その１つは磁性塗料作成時に、結合剤樹脂とともに
前記化合物を加えて、分散過程で磁性粉表面に吸着させ
る方法、後の１つはあらかじめ磁性粉に前記化合物を吸
着被覆処理を施したのち、結合剤樹脂中に分散させ塗料
化する方法である。一般に後者の方が緻密な被覆層が形
成され、分散効果、耐酸化性のすぐれたものが得られる
。In the present invention, the method of adsorbing the perfluoroalkyl phosphate ester of the compound to the magnetic powder, coating the surface thereof, and incorporating it into the magnetic layer can be roughly divided into two methods. One method is to add the above-mentioned compound together with a binder resin when creating a magnetic paint, and allow it to be adsorbed to the surface of the magnetic powder during the dispersion process.The second method is to apply the adsorption coating treatment to the magnetic powder with the above-mentioned compound in advance, and then This is a method of dispersing it in a binder resin and making it into a paint. Generally, the latter forms a denser coating layer and provides better dispersion and oxidation resistance.

表面被覆の方法としては、乾式法と湿式法が適用できる
。乾式法は、前記化合物を、直接金属磁性粉末に加え、
ヘンシェルミキサー等で混合することによって達成され
、また湿式法では前記化合物の適当な溶剤による溶液に
金属磁性粉を加え、ボールミル、サンドミル、高速イン
ペラーなどの分散機により磁性粉が１次粒子化するまで
分散させたのち、溶剤を飛散させ、４０°Ｃから６ｏ′
Ｃの温度で乾燥することによって達成される。As a surface coating method, a dry method and a wet method can be applied. In the dry method, the compound is added directly to the metal magnetic powder,
This is achieved by mixing with a Henschel mixer, etc., or in the wet method, metal magnetic powder is added to a solution of the above compound in an appropriate solvent, and the magnetic powder is mixed with a dispersing machine such as a ball mill, sand mill, or high-speed impeller until it becomes primary particles. After dispersing, scatter the solvent and heat at 40°C to 6o'
This is achieved by drying at a temperature of C.

前記化合物を、塗料作成時に加える配合割合およびあら
かじめ表面被覆処理を行なう場合の処理量は、磁性粉１
ｏｏ重量部に対して０．２部から５部の範囲で、好まし
くは１〜２部の範囲である。The compounding ratio of the above compound added at the time of paint preparation and the amount treated when surface coating treatment is performed in advance are as follows: 1 magnetic powder 1
It is in the range of 0.2 parts to 5 parts, preferably in the range of 1 to 2 parts, based on oo parts by weight.

本発明に使用される金属磁性粉としてはＦｅ。The metal magnetic powder used in the present invention is Fe.

Ｎｉ　、　Ｃｏ　、　Ｆｅ−Ｎ１−Ｃｊｏ合金、Ｆｅ−
Ｍｎ−Ｚｎ合金。Ni, Co, Fe-N1-Cjo alloy, Fe-
Mn-Zn alloy.

Ｆｅ　−Ｎｉ　−Ｚｎ合金、　Ｆｅ−Ｃｏ　−Ｎｉ−Ｏ
ｒ金合金Ｃｏ−Ｎｉ合金、Ｆｅ−Ｃｏ合金などＦｅ　、
Ｇｏ　、Ｎｉ　などを主成分とする金属磁性粉の各種で
ある。これらの磁性粉は粒子表面に酸化被膜を形成して
いても、同じように適用できる。Fe-Ni-Zn alloy, Fe-Co-Ni-O
r Gold alloy Co-Ni alloy, Fe-Co alloy etc. Fe,
These are various metal magnetic powders whose main components are Go, Ni, etc. These magnetic powders can be applied in the same way even if they have an oxide film formed on their particle surfaces.

本発明においては、磁性層を形成する結合剤樹脂、潤滑
剤、研磨剤、帯電防止剤等は従来公知のものが適用でき
る。また分散剤も必要に応じて従来公知のものの中から
使用することができる。In the present invention, conventionally known binder resins, lubricants, abrasives, antistatic agents, etc. that form the magnetic layer can be used. Further, dispersants can also be used from among conventionally known dispersants, if necessary.

実施例 以下本発明を実施例によシ、さらに具体的に説明する。Example The present invention will be explained in more detail below using examples.

（実施ｇＡＪ１） ＢＥＴ表面積が５ａｒｎ’／ｇｒ、飽和磁性量１３５ｅ
ｍｕ／ｇｒのＦｅを主成分とする強磁性粉末に対して、
前記化合物で、Ｒ１，Ｒ２の異なるＡ、Ｂ、Ｑ０３種Ｍ
のパー７０ロアルキルのリン酸エステルで表面被覆処理
を行った。(Implementation gAJ1) BET surface area is 5arn'/gr, saturation magnetism is 135e
For ferromagnetic powder mainly composed of mu/gr Fe,
In the above compound, A, B, Q03 species M with different R1 and R2
The surface was coated with a par-70 loalkyl phosphate ester.

（但し人、Ｂ　、ＣのＲ，、Ｒ２は 人：　Ｒ，、Ｒ２ともに炭素数４個のパーフロロアルキ
ル基 Ｂ：Ｒ，、Ｒ２ともに炭素数８個のパーフロロアルキル
基 Ｃ二Ｒ，、Ｒ２ともに炭素数１２個のパーフロロアルキ
ル基 である） 表面被覆処理は磁性粉１００部に対して、パーフロロア
ルキル２部、）シェフ２００部の組成で、高速ディスパ
ーミルで十分混合分散させたのち、溶剤を飛散させ、不
活性雰囲気内で６０°Ｃで乾燥させて行った。(However, R,, R2 of human, B, C is human: R,, R2 are both perfluoroalkyl groups with 4 carbon atoms B: R,, R2 are both perfluoroalkyl groups with 8 carbon atoms C2R,, Both R2 are perfluoroalkyl groups with 12 carbon atoms) The surface coating treatment was performed using a composition of 2 parts perfluoroalkyl and 200 parts chef (200 parts per 100 parts magnetic powder), which were sufficiently mixed and dispersed using a high-speed disper mill. , by sprinkling off the solvent and drying at 60°C in an inert atmosphere.

次にＡ、Ｂ、Ｃの３種類の化合物で表面被覆を施した磁
性粉を用い、次の組成で塗料化を行った。Next, magnetic powder whose surface was coated with three types of compounds A, B, and C was used to form a paint with the following composition.

磁性粉・・・・・・・・・・・・・・・・・・・・・・
・・・・・・・・・・・・・・１０２部塩酢ビ樹脂・・
・・・・・・・・・・・・・・・・・・・・・・・・・
・・・　１部部（ユニオンカーバイト社製　ＶＡＧＨ）
研摩剤（アルミナ粉）・・・・・・・・・・・・・・・
　　５部帯電防止剤（炭素粉）・・・・・・・・・・・
・・・・　　３部潤滑剤・・・・・・・・・・・・・・
・・・・・・・・・・・・・・・・・・・・・　１．５
部メチルエチルケトン・・・・・・・・・・・・・・・
・・・１６０部トルエン・・・・・・・・・・・・・・
・・・・・・・・・・・・・・・・・・・１００部シク
ロヘキサノン・・・・・・・・・・・・・・・・川・・
　５０部塗料化は、高速ディスパーミル、サンドグライ
ンダーにより十分に分散させて塗料とした。この塗料を
厚さ１１μｍのポリエステルベースフィルム上に塗布し
、乾燥９表面平滑処理、熱硬化などの各工程を経て磁気
テープに仕上げた。磁性層の厚さは２．５μｍであった
。Magnetic powder・・・・・・・・・・・・・・・・・・・・・
・・・・・・・・・・・・・・・102 parts salt vinyl acetate resin...
・・・・・・・・・・・・・・・・・・・・・・・・
... Part 1 (VAGH manufactured by Union Carbide)
Abrasive (alumina powder)・・・・・・・・・・・・・・・
5 parts Antistatic agent (carbon powder)・・・・・・・・・・・・
・・・ Three-part lubricant・・・・・・・・・・・・・・・
・・・・・・・・・・・・・・・・・・・・・ 1.5
Methyl ethyl ketone・・・・・・・・・・・・・・・
...160 parts toluene...
・・・・・・・・・・・・・・・・・・100 parts cyclohexanone・・・・・・・・・・・・・・・・・・・
To make a 50-part paint, the mixture was sufficiently dispersed using a high-speed disper mill and a sand grinder to form a paint. This coating material was applied onto a polyester base film having a thickness of 11 μm, and was completed into a magnetic tape through various steps such as drying, surface smoothing, and heat curing. The thickness of the magnetic layer was 2.5 μm.

（比較例１） 実施列１に用いた磁性粉１ｏＯ部に対して、で示される
化合物（但し、Ｒ，、Ｒは炭素数８個のアルキル基）２
部、メチルエチルケトン２００部の組成で、実施列１と
同じ方法で表面被覆処理を行った。この表面処理磁性粉
を用いて、実施例１と同一組成で、同一条件で塗料化し
て、テープ化した。(Comparative Example 1) For 100 parts of the magnetic powder used in Example 1, a compound represented by (where R, , R is an alkyl group having 8 carbon atoms) 2
The surface coating treatment was performed in the same manner as in Example 1 using a composition of 200 parts of methyl ethyl ketone and 200 parts of methyl ethyl ketone. Using this surface-treated magnetic powder, it was made into a paint with the same composition and under the same conditions as in Example 1, and then made into a tape.

（比較列２） 実施列１で用いた磁性粉に処理を加えず、実施レリ１と
同一組成、同一条件で塗料化して、テープ化した。(Comparison row 2) The magnetic powder used in Example row 1 was made into a paint with the same composition and under the same conditions as Example Reli 1 without any treatment, and then made into a tape.

以上の実施例１．比較例の実験において、磁性粉の分散
性の比較を、分散性の代表特性である塗工直後の表面光
沢度（４６°〜４５°）を測定して行った。またテープ
の耐酸化性の比較は、各試作テープを６０°Ｃ，９０％
ＲＨに設定した恒温恒湿槽内に２０日間放置し、放置前
後の飽和磁束密度（Ｂｍｇ　、８ｍ２ｇ）の変化率を測
定して行った。Example 1 above. In the comparative example experiment, the dispersibility of the magnetic powder was compared by measuring the surface glossiness (46° to 45°) immediately after coating, which is a typical characteristic of dispersibility. In addition, to compare the oxidation resistance of the tapes, each prototype tape was heated at 60°C and 90%
The sample was left in a constant temperature and humidity chamber set at RH for 20 days, and the rate of change in saturation magnetic flux density (Bmg, 8 m2g) before and after the leave was measured.

それぞれの結果は第１表の通シであった。The results for each were as shown in Table 1.

（以下余白）(Margin below)

Claims (1)

【特許請求の範囲】 非磁性の支持体上に、金属磁性粉末を結合剤樹脂中に分
散させてなる磁性層を形成することにより構成され、か
つ金属磁性粉末があらかじめ▲数式、化学式、表等があ
ります▼ で示される化合物（但しＲ＿１、Ｒ＿２は炭素数が４〜
１８個のパーフロロアルキル基）で表面被覆されたもの
であることを特徴とする磁気記録媒体。[Scope of Claims] A magnetic layer formed by dispersing metal magnetic powder in a binder resin is formed on a non-magnetic support, and the metal magnetic powder is prepared in advance by ▲mathematical formulas, chemical formulas, tables, etc. There is a compound shown by ▼ (however, R_1 and R_2 have 4 to 4 carbon atoms)
1. A magnetic recording medium, the surface of which is coated with 18 perfluoroalkyl groups.