JPH031320A - Magnetic powder and magnetic recording medium using this powder - Google Patents

Magnetic powder and magnetic recording medium using this powder

Info

Publication number
JPH031320A
JPH031320A JP13528289A JP13528289A JPH031320A JP H031320 A JPH031320 A JP H031320A JP 13528289 A JP13528289 A JP 13528289A JP 13528289 A JP13528289 A JP 13528289A JP H031320 A JPH031320 A JP H031320A
Authority
JP
Japan
Prior art keywords
magnetic
powder
magnetic powder
silicon
alkali metal
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
JP13528289A
Other languages
Japanese (ja)
Inventor
Hiroaki Terasawa
寛了 寺澤
Toshio Kanzaki
寿夫 神崎
Toshinobu Sueyoshi
俊信 末吉
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Maxell Ltd
Original Assignee
Hitachi Maxell Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hitachi Maxell Ltd filed Critical Hitachi Maxell Ltd
Priority to JP13528289A priority Critical patent/JPH031320A/en
Publication of JPH031320A publication Critical patent/JPH031320A/en
Pending legal-status Critical Current

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  • Magnetic Record Carriers (AREA)

Abstract

PURPOSE:To obtain such a magnetic powder that has no deterioration in magnetic characteristics and has large coercive force by coating oxide-type magnetic powder with silicon compd. and then coating the powder with alkali metal compd. CONSTITUTION:First, a base coating layer comprising silicon compd. is formed on the particle of oxde-type magnetic powder, For example, The powder is dispersed in ethanol, into which an org. silicon comp. such as tetraaldoxysilane is added, and hydrolysis of the compd is effected to form a silicon hydroxide film on the powder particle. then the powder is coated with aldali metal compd. to obtain the magnetic powder for magnetic recording elements. Thereby, magnetic characteristics of the powder can not be affected by the coating films and the obtd. powder has large coercive force.

Description

【発明の詳細な説明】 〔産業上の利用分野〕 この発明は、磁気記録素子として有用な磁性粉末と、こ
の磁性粉末を用いた磁気テープや磁気ディスクなどの磁
気記録媒体に関する。
DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic powder useful as a magnetic recording element and a magnetic recording medium such as a magnetic tape or a magnetic disk using this magnetic powder.

〔従来の技術〕[Conventional technology]

磁気記録素子として、7−Fezo、、粉末、Fe3O
4粉末、Co含有r−Fe20.粉末、バリウムフェラ
イト粉末などの酸化鉄系磁性粉末がよく知られている。
As a magnetic recording element, 7-Fezo, powder, Fe3O
4 powder, Co-containing r-Fe20. Iron oxide magnetic powders such as barium ferrite powder and barium ferrite powder are well known.

これら粉末はこれを分散結着するバインダとともに非磁
性支持体上に塗着することによって磁性層を構成させ、
磁気テープや磁気ディスクなどの磁気記録媒体とされる
These powders constitute a magnetic layer by coating them on a non-magnetic support together with a binder that disperses and binds them.
It is considered to be a magnetic recording medium such as magnetic tape or magnetic disk.

従来より、この種の磁気記録媒体の耐久性を改良するた
めに、磁性粉末を分散結着するバインダとして分子内に
リン酸基、カルボン酸基などの酸性の官能基を有するも
のを用いる一方、磁性粉末の表面にアルカリ金属化合物
の被膜を形成しておき、これと上記官能基との相互作用
によってバインダに対する磁性粉末の結着力を強め、磁
性層の機械的強度を高めることがよく行われている。
Conventionally, in order to improve the durability of this type of magnetic recording medium, binders having acidic functional groups such as phosphoric acid groups and carboxylic acid groups in their molecules have been used as binders for dispersing and binding magnetic powder. It is a common practice to form a film of an alkali metal compound on the surface of the magnetic powder, and the interaction between this film and the above-mentioned functional groups strengthens the adhesion of the magnetic powder to the binder, thereby increasing the mechanical strength of the magnetic layer. There is.

〔発明が解決しようとする課題〕[Problem to be solved by the invention]

しかるに、上記従来の改良手段においては、酸化鉄系磁
性粉末の表面に被膜状に設けられるアルカリ金属化合物
に起因して、磁性粉末同志の相互作用が強くなって磁気
特性に悪影響を及ぼし、特にその保磁力が著しく低下し
、電磁変換特性やさらに耐久性の面で問題があった。
However, in the above-mentioned conventional improvement means, due to the alkali metal compound provided in the form of a film on the surface of the iron oxide-based magnetic powder, the interaction between the magnetic powders becomes strong, which adversely affects the magnetic properties. The coercive force decreased significantly, causing problems in electromagnetic conversion characteristics and durability.

この発明は、上述の事情に照らし、アルカリ金属化合物
の被膜に起因した磁気特性への悪影響がみられない、特
に保磁力の大幅な低下がみられない酸化鉄系磁性粉末を
提供するとともに、これを用いて耐久性および電磁変換
特性にすぐれた磁気記録媒体を得ることを目的としてい
る。
In light of the above-mentioned circumstances, the present invention provides an iron oxide-based magnetic powder that does not have an adverse effect on magnetic properties caused by a coating of an alkali metal compound, and in particular does not show a significant decrease in coercive force. The purpose of this study is to obtain a magnetic recording medium with excellent durability and electromagnetic conversion characteristics.

〔課題を解決するための手段〕[Means to solve the problem]

この発明者らは、上記の目的を達成するために鋭意検討
した結果、酸化鉄系磁性粉末の表面に特定の下地処理を
施したのちにアルカリ金属化合物の被膜を形成すると、
上記被膜に起因した磁気特性への悪影響が回避されて、
大きな保磁力を示す磁性粉末が得られ、この磁性粉末と
分子内に酸性の官能基を有するバインダとを用いて磁性
層を形成した磁気記録媒体によると、耐久性および電磁
変換特性の両面ですぐれた性能を発揮させうろことを知
り、この発明をなすに至った。
As a result of intensive studies to achieve the above object, the inventors found that if a coating of an alkali metal compound is formed on the surface of iron oxide magnetic powder after a specific surface treatment,
The negative effect on magnetic properties caused by the above coating is avoided,
Magnetic powder exhibiting a large coercive force has been obtained, and a magnetic recording medium in which a magnetic layer is formed using this magnetic powder and a binder having an acidic functional group in its molecules has excellent both durability and electromagnetic conversion characteristics. This discovery led to the creation of this invention.

すなわち、この発明の第1は、酸化鉄系磁性粉末の表面
にケイ素化合物からなる下地被膜を介してアルカリ金属
化合物の被膜が形成されてなる磁性粉末に係るものであ
る。
That is, the first aspect of the present invention relates to a magnetic powder in which a coating of an alkali metal compound is formed on the surface of an iron oxide-based magnetic powder with an underlying coating made of a silicon compound interposed therebetween.

また、この発明の第2は、非磁性支持体上に上記第1の
発明に係る特定の磁性粉末と酸性の官能基を有するバイ
ンダとを含む磁性層が設けられてなる磁気記録媒体に係
るものである。
A second aspect of the present invention relates to a magnetic recording medium in which a magnetic layer containing the specific magnetic powder according to the first aspect and a binder having an acidic functional group is provided on a non-magnetic support. It is.

〔発明の構成・作用〕[Structure and operation of the invention]

この発明の磁性粉末において、その表面に所要の被膜を
形成するべき酸化鉄系磁性粉末としては、平均粒子径が
通常0.1〜1μm、平均軸比(平均長軸径/平均短軸
径)が通常5〜15程度の針状の磁性粉末が好ましく用
いられる。この酸化鉄系磁性粉末には、既述したr−F
e、O,粉末、Fe、o、粉末、Co含有r−Fe、O
,粉末、バリウムフェライト粉末などの公知の各種粉末
がすべて包含される。保磁力は通常100〜2.000
エルステツド、飽和磁化は50〜200 emu/g程
度である。
In the magnetic powder of the present invention, the iron oxide magnetic powder that should form the required coating on its surface usually has an average particle diameter of 0.1 to 1 μm and an average axial ratio (average major axis diameter/average minor axis diameter). Acicular magnetic powder having a diameter of about 5 to 15 is preferably used. This iron oxide magnetic powder has the above-mentioned r-F
e, O, powder, Fe, o, powder, Co-containing r-Fe, O
, powder, barium ferrite powder, etc. are all included. Coercive force is usually 100-2.000
The saturation magnetization is about 50 to 200 emu/g.

この発明では、このような酸化鉄系磁性粉末の表面にま
ずケイ素化合物からなる下地被膜を形成する。この被膜
の形成は、たとえば酸化鉄系磁性粉末をエタノールなど
の液中に分散させ、これにテトラアルコキシシランなど
の有機ケイ素化合物を加えたのち、この化合物を加水分
解して、上記粉末の表面にケイ素の水酸化物の被膜を形
成するなどの方法により、行うことができる。
In this invention, a base film made of a silicon compound is first formed on the surface of such iron oxide magnetic powder. This film is formed by dispersing iron oxide magnetic powder in a liquid such as ethanol, adding an organosilicon compound such as tetraalkoxysilane, and then hydrolyzing this compound to coat the surface of the powder. This can be done by a method such as forming a silicon hydroxide film.

なお、このようなケイ素化合物の被膜を磁性粉末の表面
に形成して、この粉末のバインダ中での分散性などを高
めることは、既に公知の技術である。しかし、この発明
のように、アルカリ金属化合物の被膜を形成するにあた
って、その下地処理としてケイ素化合物の被膜を形成し
、これにより酸化鉄系磁性粉末の保磁力の低下などを防
ぎ、これを記録素子とした磁気記録媒体の耐久性と電磁
変換特性とを共に高度に満足させることについては全く
知られていなかったことである。
Note that it is already a known technique to form a film of such a silicon compound on the surface of magnetic powder to improve the dispersibility of this powder in a binder. However, in forming the alkali metal compound film as in the present invention, a silicon compound film is formed as a base treatment, thereby preventing a decrease in the coercive force of the iron oxide magnetic powder. It was completely unknown that magnetic recording media could satisfy both durability and electromagnetic characteristics to a high degree.

ケイ素化合物からなる下地被膜の量は、一般に酸化鉄系
磁性粉末に対しケイ素基準で0.05〜lO重量%、特
に好適には0.1〜5重量%となるようにするのがよい
。この量が過少では所期の効果が得られず、また過多と
なると飽和磁化などの磁気特性の低下がみられ、好まし
くない。
The amount of the undercoat made of the silicon compound is generally 0.05 to 10% by weight, particularly preferably 0.1 to 5% by weight based on silicon, based on the iron oxide magnetic powder. If this amount is too small, the desired effect will not be obtained, and if it is too large, magnetic properties such as saturation magnetization will deteriorate, which is not preferable.

この発明においては、このようなケイ素化合物からなる
下地被膜を形成したのち、さらにこの上にアルカリ金属
化合物の被膜を形成して、磁気jd録素子としての磁性
粉末を得る。ここで、アルカリ金属化合物の被膜の形成
は、たとえば上記の下地被膜を有する酸化鉄系磁性粉末
をエタノールなどの液中に分散させ、これにLi、Na
、になどのアルカリ金属のアルコラードなどの化合物を
加えたのち、この化合物を加水分解して、上記粉末の表
面にアルカリ金属の水酸化物の被膜を形成するなどの方
法によ、す、行うことができる。
In the present invention, after forming a base coat made of such a silicon compound, a coat of an alkali metal compound is further formed thereon to obtain a magnetic powder as a magnetic JD recording element. Here, the formation of the alkali metal compound coating is carried out by dispersing, for example, iron oxide-based magnetic powder having the above-mentioned base coating in a liquid such as ethanol, and adding Li, Na, etc.
After adding a compound such as alcolade of an alkali metal such as , to, hydrolyzing this compound to form a film of alkali metal hydroxide on the surface of the powder, etc. I can do it.

このアルカリ金属化合物の被膜の量としては、一般に酸
化鉄系磁性粉末に対しアルカリ金属基準で0.01〜5
重量%、特に好適には0.05〜1重量%となるように
するのがよい、この量が過少では耐久性などの改善効果
が得られず、また過多となると飽和磁化などの磁気特性
の低下がみられ、好ましくない。
The amount of this alkali metal compound coating is generally 0.01 to 5% based on the alkali metal based on the iron oxide magnetic powder.
% by weight, preferably 0.05 to 1% by weight. If this amount is too small, it will not be possible to improve the durability, and if it is too large, it will deteriorate magnetic properties such as saturation magnetization. A decrease is observed, which is not desirable.

この発明の磁気記録媒体は、このような磁性粉末と酸性
の官能基を有するバインダとを含む磁性層がポリエステ
ルフィルムなどの非磁性支持体の上に設けられてなるも
のであり、常法に準じて製造することができる。たとえ
ば、上記の磁性粉末と上記のバインダと必要に応じて配
合される各種の添加剤とを有機溶媒中に添加混合して磁
性塗料を調製し、この塗料を非磁性支持体上に塗布、乾
燥して所要厚さの磁性層を形成したのち、カレンダー加
工などの適当な後処理を施し、所要の磁気記録媒体の形
状とすればよい。
The magnetic recording medium of the present invention has a magnetic layer containing such magnetic powder and a binder having an acidic functional group provided on a non-magnetic support such as a polyester film, and is prepared by a conventional method. It can be manufactured using For example, a magnetic paint is prepared by adding and mixing the above-mentioned magnetic powder, the above-mentioned binder, and various additives blended as necessary in an organic solvent, and this paint is applied onto a non-magnetic support and dried. After forming a magnetic layer with a desired thickness, appropriate post-processing such as calendering may be performed to form the desired shape of the magnetic recording medium.

上記のバインダとしては、塩化ビニル−酢酸ビニル系共
重合体、ポリビニルブチラール系樹脂、繊維素系樹脂、
ポリウレタン系樹脂、ポリエステル系樹脂、架橋剤とし
てのポリイソシアネート化合物、放射線硬化型樹脂など
、従来より磁気記録媒体の磁性層用のバインダとして知
られるものをいずれも単独でまたは二種以上を混合して
使用できる。ただし、これらバインダの一部または全部
は、リン酸基、カルボン酸基、スルホン酸基などの酸性
の官能基を分子内に有するものであることが必要である
Examples of the above binders include vinyl chloride-vinyl acetate copolymers, polyvinyl butyral resins, cellulose resins,
Polyurethane resins, polyester resins, polyisocyanate compounds as crosslinking agents, radiation curing resins, and other binders conventionally known as binders for magnetic layers of magnetic recording media can be used singly or in combination of two or more. Can be used. However, it is necessary that some or all of these binders have an acidic functional group such as a phosphoric acid group, a carboxylic acid group, or a sulfonic acid group in the molecule.

有機溶剤としては、シクロヘキサノン、メチルエチルケ
トン、メチルイソブチルケトンなどのケトン系溶剤、酢
酸エチル、酢酸ブチルなどのエステル系溶剤、ベンゼン
、トルエン、キシレンなどの芳香族炭化水素系溶剤、イ
ソプロピルアルコールなどのアルコール系溶剤、ジメチ
ルホルムアミドなどの酸アミド系溶剤、ジメチルスルホ
キシドなどのスルホキシド系溶剤、テトラヒドロフラン
、ジオキサンなどのエーテル系溶剤など、使用するバイ
ンダを溶解するのに通した溶剤が特に制限されることな
く単独でまたは二種以上を混合して使用できる。
Examples of organic solvents include ketone solvents such as cyclohexanone, methyl ethyl ketone, and methyl isobutyl ketone, ester solvents such as ethyl acetate and butyl acetate, aromatic hydrocarbon solvents such as benzene, toluene, and xylene, and alcohol solvents such as isopropyl alcohol. There are no particular restrictions on the solvent used to dissolve the binder, such as acid amide solvents such as dimethylformamide, sulfoxide solvents such as dimethyl sulfoxide, and ether solvents such as tetrahydrofuran and dioxane. Can be used in combination with more than one species.

また、必要に応じて配合される添加剤としては、分散剤
、潤滑剤、研摩剤、帯電防止剤、充填剤などが挙げられ
る。
Further, additives that may be added as necessary include dispersants, lubricants, abrasives, antistatic agents, fillers, and the like.

〔発明の効果〕〔Effect of the invention〕

以上のように、この発明においては、酸化鉄系磁性粉末
の表面にケイ素化合物の被膜を介してアルカリ金属化合
物の被膜を形成したことにより、磁気特性の劣化がみら
れない、特に大きな保磁力を示す磁性粉末が得られ、こ
の磁性粉末と酸性の官能基を有するバインダとを含む磁
性層を非磁性支持体上に設けることにより、耐久性およ
び電磁変換特性に共にすぐれた磁気記録媒体を得ること
ができる。
As described above, in this invention, by forming an alkali metal compound coating on the surface of iron oxide magnetic powder via a silicon compound coating, a particularly large coercive force can be achieved without any deterioration of magnetic properties. A magnetic recording medium having excellent durability and electromagnetic conversion characteristics can be obtained by providing a magnetic layer containing this magnetic powder and a binder having an acidic functional group on a non-magnetic support. I can do it.

〔実施例〕〔Example〕

つぎに、この発明を実施例に基づいて具体的に説明する
Next, the present invention will be specifically explained based on examples.

実施例1 平均粒子径0.2μm、平均軸比10の針状のCO含有
r−Fe、O,粉末100gを、21のエタノール中に
分散させ、これに7.5gの5i(OCz Hs )a
を加え、撹拌しながら60℃まで昇温後、7.8gの水
を徐々に滴下して5t(OCzHs)aを加水分解し、
上記粉末の表面にケイ素の水酸化物の被膜を形成した。
Example 1 100 g of acicular CO-containing r-Fe, O, powder with an average particle size of 0.2 μm and an average axial ratio of 10 was dispersed in 21 ethanol, and 7.5 g of 5i(OCz Hs ) a
was added, the temperature was raised to 60°C while stirring, and 7.8g of water was gradually added dropwise to hydrolyze 5t(OCzHs)a.
A silicon hydroxide film was formed on the surface of the powder.

ついで、この下地被膜を形成したCo含有γFe、O,
粉末を含むエタノール中に、さらに300gのLi0C
,H5の5重量%エタノール溶液を加え、60℃を保っ
たまま63gの水を徐々に滴下してLi0C,H6を加
水分解し、リチウムの水酸化物の被膜を形成した。この
被膜形成後、80℃で乾燥して、磁性粉末を得た。
Next, Co-containing γFe, O,
An additional 300 g of Li0C in ethanol containing powder
, H5 was added thereto, and 63 g of water was gradually added dropwise while maintaining the temperature at 60° C. to hydrolyze Li0C and H6 to form a lithium hydroxide film. After forming this film, it was dried at 80°C to obtain magnetic powder.

つぎに、この磁性粉末100重量部、リン酸基を含む塩
化ビニル−酢酸ビニル−ビニルアルコル共重合体1O0
5重量部、ミリスチン酸4重量部、トルエン1)0重量
部、メチルエチルケトン100重量部の組成からなる磁
性塗料を常法により調製した。この塗料を厚さ10μm
のポリエステルフィルム上に乾燥後の厚さが3μmとな
るように塗布し、配向強度1,000ガウスで配向処理
し、乾燥して、磁気テープを作製した。
Next, 100 parts by weight of this magnetic powder, 100 parts by weight of vinyl chloride-vinyl acetate-vinyl alcohol copolymer containing a phosphoric acid group,
A magnetic paint having a composition of 5 parts by weight, 4 parts by weight of myristic acid, 1) part by weight of toluene, and 100 parts by weight of methyl ethyl ketone was prepared by a conventional method. Apply this paint to a thickness of 10 μm.
The magnetic tape was coated onto a polyester film to have a dry thickness of 3 μm, subjected to orientation treatment at an orientation strength of 1,000 Gauss, and dried to produce a magnetic tape.

実施例2 実施例1の磁性粉末の製法におけるLjOC。Example 2 LjOC in the method for producing magnetic powder of Example 1.

H3の5重量%エタノール溶液に代えて、120gのN
a0CzHsの5重量%エタノール溶液を用いるととも
に、これを加水分解させるための水の量を19gに変更
した以外は、実施例1と同様にして、ケイ素の水酸化物
の被膜上にナトリウムの水酸化物の被膜を有する磁性粉
末を得た。つぎに、この磁性粉末を用いて実施例1と同
様にして、磁気テープを作製した。
120 g of N in place of the 5 wt% ethanol solution of H3
Sodium hydroxide was deposited on the silicon hydroxide film in the same manner as in Example 1, except that a 5% by weight ethanol solution of a0CzHs was used and the amount of water for hydrolyzing it was changed to 19 g. A magnetic powder having a coating of the substance was obtained. Next, a magnetic tape was produced in the same manner as in Example 1 using this magnetic powder.

実施例3 実施例1の磁性粉末の製法におけるLi0CzH5の5
重量%エタノール溶液に代えて、86gのKOCzll
sの5重量%エタノール溶液を用いるとともに、これを
加水分解させるための水の量を12gに変更した以外は
、実施例1と同様にして、ケイ素の水酸化物の被膜上に
カリウムの水酸化物の被膜を有する磁性粉末を得た。つ
ぎに、この磁性粉末を用いて実施例1と同様にして、磁
気テープを作製した。
Example 3 5 of Li0CzH5 in the method for producing magnetic powder of Example 1
86 g of KOCzll instead of wt% ethanol solution
Potassium hydroxide was deposited on the silicon hydroxide film in the same manner as in Example 1, except that a 5% by weight ethanol solution of S was used and the amount of water for hydrolyzing it was changed to 12 g. A magnetic powder having a coating of the substance was obtained. Next, a magnetic tape was produced in the same manner as in Example 1 using this magnetic powder.

実施例4 実施例1の磁性粉末の製法におけるL i OCzH5
の5重量%エタノール溶液に代えて、150gのL i
 OCz Hsの5重量%エタノール溶液と60gのN
a0CzHsの5重量%エタノール溶液との混合液を用
いるとともに、これを加水分解させるための水の量を4
1gに変更した以外は、実施例1と同様にして、ケイ素
の水酸化物の被膜上にリチウムとナトリウムとの混合ア
ルカリの水酸化物の被膜を有する磁性粉末を得た。つぎ
に、この磁性粉末を用いて実施例1と同様にして、磁気
テープを作製した。
Example 4 Li OCzH5 in the method for producing magnetic powder of Example 1
150 g of Li
5 wt% ethanol solution of OCz Hs and 60 g N
A mixed solution of a0CzHs with a 5% by weight ethanol solution was used, and the amount of water for hydrolyzing this was 4
A magnetic powder having a mixed alkali hydroxide film of lithium and sodium on a silicon hydroxide film was obtained in the same manner as in Example 1, except that the amount was changed to 1 g. Next, a magnetic tape was produced in the same manner as in Example 1 using this magnetic powder.

参考例1 未処理のCO含含有−176203粉末をそのまま磁気
記録素子用の磁性粉末とし、この磁性粉末を用いて実施
例1と同様にして、磁気テープを作製した。
Reference Example 1 An untreated CO-containing -176203 powder was used as a magnetic powder for a magnetic recording element, and a magnetic tape was produced in the same manner as in Example 1 using this magnetic powder.

参考例2 Co含含有−Fe、03粉末の表面にケイ素の水酸化物
の被膜を形成しただけで、この上にリチウムの水酸化物
の被膜を形成しなかった以外は、実施例1と同様にして
磁性粉末を得、この粉末を用いて実施例1と同様にして
、磁気テープを作製した。
Reference Example 2 Same as Example 1 except that a silicon hydroxide film was only formed on the surface of the Co-containing -Fe,03 powder and a lithium hydroxide film was not formed thereon. A magnetic powder was obtained, and a magnetic tape was produced in the same manner as in Example 1 using this powder.

比較例1〜4 下地被膜としてのケイ素の水酸化物の被膜を形成しない
で、Co含含有−Fe、O,粉末の表面に直接アルカリ
金属の水酸化物の被膜を形成した以外は、実施例1〜4
と同様にして、4種の磁性粉末を得、これらの磁性粉末
を用いて実施例1と同様にして、4種の磁気テープを作
製した。
Comparative Examples 1 to 4 Examples except that an alkali metal hydroxide film was directly formed on the surface of the Co-containing -Fe, O, powder without forming a silicon hydroxide film as a base film. 1-4
Four types of magnetic powders were obtained in the same manner as in Example 1, and four types of magnetic tapes were produced using these magnetic powders in the same manner as in Example 1.

以上の実施例、参考例および比較例の各磁性粉末につき
、磁気特性として保磁力(Hc)、飽和磁化〔δS〕を
測定した。また、上記の実施例。
Coercive force (Hc) and saturation magnetization [δS] were measured as magnetic properties for each of the magnetic powders of the above Examples, Reference Examples, and Comparative Examples. Also, the above embodiments.

参考例および比較例の各磁気テープにつき、耐久性試験
として低温(−5℃)でのスチル特性、電磁変換特性と
してRF比出力調べた。これらの試験結果をまとめて、
つぎの第1表に示す。
For each of the magnetic tapes of Reference and Comparative Examples, still characteristics at low temperature (-5° C.) were examined as a durability test, and RF specific output was examined as electromagnetic conversion characteristics. Combining these test results,
It is shown in Table 1 below.

なお、上記のスチル特性は、市販VTRを用い、温度−
5℃の環境下でスチールモールドにおいて出力が初期出
力の2/3に低下するまでの時間(分)を測定した。ま
た、RF比出力、5 M 1) zの信号を一定レベル
で記録することにより測定し、この測定結果を参考例1
の磁気テープを基準(0dB)とした相対値にて示した
Note that the above still characteristics were determined using a commercially available VTR, and the temperature -
The time (minutes) until the output decreased to 2/3 of the initial output was measured in a steel mold in an environment of 5°C. In addition, the RF specific output was measured by recording the 5 M 1) z signal at a constant level, and the measurement results were used in Reference Example 1.
It is expressed as a relative value with the magnetic tape as a reference (0 dB).

第  1  表 上表の結果から、この発明の磁性粉末(実施例1〜4)
は、高い保磁力を維持しており、この粉末と酸性の官能
基を有するバインダとを含む磁性層を非磁性支持体上に
設けてなるこの発明の磁気テープ(実施例1〜4)は、
耐久性と電磁変換特性とに共にすぐれていることが明ら
かである。
From the results shown in Table 1, the magnetic powder of the present invention (Examples 1 to 4)
maintains a high coercive force, and the magnetic tapes of the present invention (Examples 1 to 4) include a magnetic layer containing this powder and a binder having an acidic functional group provided on a non-magnetic support.
It is clear that both durability and electromagnetic conversion characteristics are excellent.

これに対し、酸化鉄系磁性粉末の表面に直接アルカリ金
属の水酸化物の被膜を形成した磁性粉末(比較例1〜4
)は、保磁力が極端に低下しており、これを用いた磁気
テープは電磁変換特性に劣り、また耐久性の改善効果も
ほとんどみられないことがわかる。また、酸化鉄系磁性
粉末の表面にケイ素の水酸化物の被膜のみを形成した参
考例2の磁性粉末を記録素子とした磁気テープにあって
は、主に耐久性の改善効果に乏しいものであることがわ
かる。
In contrast, magnetic powders in which a film of alkali metal hydroxide was directly formed on the surface of iron oxide-based magnetic powders (Comparative Examples 1 to 4)
) has an extremely low coercive force, and it can be seen that magnetic tapes using this have poor electromagnetic conversion characteristics and hardly any improvement in durability. In addition, the magnetic tape using the magnetic powder of Reference Example 2, in which only a silicon hydroxide film was formed on the surface of the iron oxide magnetic powder, as a recording element mainly lacked the effect of improving durability. I understand that there is something.

特許出願人  日立マクセル株式会社Patent applicant: Hitachi Maxell, Ltd.

Claims (3)

【特許請求の範囲】[Claims] (1)酸化鉄系磁性粉末の表面にケイ素化合物からなる
下地被膜を介してアルカリ金属化合物の被膜が形成され
てなる磁性粉末。
(1) A magnetic powder in which a coating of an alkali metal compound is formed on the surface of an iron oxide magnetic powder with an underlying coating made of a silicon compound interposed therebetween.
(2)ケイ素化合物からなる下地被膜の量が酸化鉄系磁
性粉末に対しケイ素基準で0.05〜10重量%、アル
カリ金属化合物の被膜の量が酸化鉄系磁性粉末に対しア
ルカリ金属基準で0.01〜5重量%である請求項(1
)に記載の磁性粉末。
(2) The amount of the underlayer film made of a silicon compound is 0.05 to 10% by weight based on silicon relative to the iron oxide magnetic powder, and the amount of the alkali metal compound film is 0.05 to 10% by weight based on the alkali metal based on the iron oxide magnetic powder. .01 to 5% by weight (1)
) Magnetic powder described in .
(3)非磁性支持体上に請求項(1)または(2)に記
載の磁性粉末と酸性の官能基を有するバインダとを含む
磁性層が設けられてなる磁気記録媒体。
(3) A magnetic recording medium comprising a magnetic layer containing the magnetic powder according to claim (1) or (2) and a binder having an acidic functional group on a non-magnetic support.
JP13528289A 1989-05-29 1989-05-29 Magnetic powder and magnetic recording medium using this powder Pending JPH031320A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP13528289A JPH031320A (en) 1989-05-29 1989-05-29 Magnetic powder and magnetic recording medium using this powder

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP13528289A JPH031320A (en) 1989-05-29 1989-05-29 Magnetic powder and magnetic recording medium using this powder

Publications (1)

Publication Number Publication Date
JPH031320A true JPH031320A (en) 1991-01-08

Family

ID=15148060

Family Applications (1)

Application Number Title Priority Date Filing Date
JP13528289A Pending JPH031320A (en) 1989-05-29 1989-05-29 Magnetic powder and magnetic recording medium using this powder

Country Status (1)

Country Link
JP (1) JPH031320A (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH07224098A (en) * 1978-11-24 1995-08-22 F Hoffmann La Roche Ag Interferon product derived from human blood
EP1063639A1 (en) * 1999-06-24 2000-12-27 Toda Kogyo Corporation Magnetic composite particles for magnetic recording medium, process for producing the same and magnetic recording medium using the same

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH07224098A (en) * 1978-11-24 1995-08-22 F Hoffmann La Roche Ag Interferon product derived from human blood
EP1063639A1 (en) * 1999-06-24 2000-12-27 Toda Kogyo Corporation Magnetic composite particles for magnetic recording medium, process for producing the same and magnetic recording medium using the same

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