JPH0746418B2 - Magnetic recording medium - Google Patents
Magnetic recording mediumInfo
- Publication number
- JPH0746418B2 JPH0746418B2 JP60271374A JP27137485A JPH0746418B2 JP H0746418 B2 JPH0746418 B2 JP H0746418B2 JP 60271374 A JP60271374 A JP 60271374A JP 27137485 A JP27137485 A JP 27137485A JP H0746418 B2 JPH0746418 B2 JP H0746418B2
- Authority
- JP
- Japan
- Prior art keywords
- particles
- cro
- magnetic
- recording medium
- magnetic recording
- 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.)
- Expired - Lifetime
Links
- 230000005291 magnetic effect Effects 0.000 title claims description 22
- 239000002245 particle Substances 0.000 claims description 29
- 229910001566 austenite Inorganic materials 0.000 claims description 15
- 239000011230 binding agent Substances 0.000 claims description 10
- 239000011347 resin Substances 0.000 claims description 6
- 229920005989 resin Polymers 0.000 claims description 6
- 239000006229 carbon black Substances 0.000 claims description 3
- 230000005294 ferromagnetic effect Effects 0.000 claims description 3
- 239000011248 coating agent Substances 0.000 claims description 2
- 238000000576 coating method Methods 0.000 claims description 2
- 239000000463 material Substances 0.000 claims description 2
- 239000004033 plastic Substances 0.000 claims description 2
- 229920003023 plastic Polymers 0.000 claims description 2
- 230000000052 comparative effect Effects 0.000 description 6
- 230000007423 decrease Effects 0.000 description 5
- 238000002834 transmittance Methods 0.000 description 5
- 230000005540 biological transmission Effects 0.000 description 4
- 230000004907 flux Effects 0.000 description 4
- 239000000696 magnetic material Substances 0.000 description 4
- 239000006249 magnetic particle Substances 0.000 description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 3
- 229910052799 carbon Inorganic materials 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 239000010419 fine particle Substances 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 125000004432 carbon atom Chemical group C* 0.000 description 2
- 235000014113 dietary fatty acids Nutrition 0.000 description 2
- 229930195729 fatty acid Natural products 0.000 description 2
- 239000000194 fatty acid Substances 0.000 description 2
- 150000004665 fatty acids Chemical class 0.000 description 2
- 239000003973 paint Substances 0.000 description 2
- 229920006267 polyester film Polymers 0.000 description 2
- 230000035945 sensitivity Effects 0.000 description 2
- 230000003746 surface roughness Effects 0.000 description 2
- 229920001187 thermosetting polymer Polymers 0.000 description 2
- JOYRKODLDBILNP-UHFFFAOYSA-N Ethyl urethane Chemical compound CCOC(N)=O JOYRKODLDBILNP-UHFFFAOYSA-N 0.000 description 1
- BZHJMEDXRYGGRV-UHFFFAOYSA-N Vinyl chloride Chemical compound ClC=C BZHJMEDXRYGGRV-UHFFFAOYSA-N 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 150000001298 alcohols Chemical class 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000004040 coloring Methods 0.000 description 1
- 229920001577 copolymer Polymers 0.000 description 1
- 238000001723 curing Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000001227 electron beam curing Methods 0.000 description 1
- 150000002148 esters Chemical class 0.000 description 1
- 239000003302 ferromagnetic material Substances 0.000 description 1
- 239000012948 isocyanate Substances 0.000 description 1
- 150000002513 isocyanates Chemical class 0.000 description 1
- 239000000314 lubricant Substances 0.000 description 1
- 239000006247 magnetic powder Substances 0.000 description 1
- 230000007257 malfunction Effects 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 239000000049 pigment Substances 0.000 description 1
- 229920001169 thermoplastic Polymers 0.000 description 1
- 239000004416 thermosoftening plastic Substances 0.000 description 1
Landscapes
- Magnetic Record Carriers (AREA)
- Paints Or Removers (AREA)
Description
【発明の詳細な説明】 〔技術分野〕 本発明は磁気記録媒体、特にビデオテープ等の高密度記
録に適した磁気記録媒体に関する。TECHNICAL FIELD The present invention relates to a magnetic recording medium, particularly to a magnetic recording medium suitable for high density recording such as a video tape.
近年、磁気記録媒体の発展は目ざましく、オーデイオテ
ープ、ビデオテープ、フロツピーデイスクなどが広く使
用されている。特に最近は、家庭用ビデオ機器が急速に
普及し、ビデオテープの伸びが著るしい。それに伴な
い、ビデオテープに要求される特性も、年々、きびしく
なつてきている。例えば、高画質、高耐久性がますます
求められ、技術的検討が進められている。高画質ビデオ
テープ用磁性材としては、低ノイズを目的として、粒子
サイズの小さい強磁性材が使われる傾向にあるが、近
年、微粒子の磁性粉を使用することにより、ビデオS/N
は、飛躍的に改善され、使用者の要求に応えている。In recent years, the development of magnetic recording media has been remarkable, and audio tapes, video tapes, floppy discs and the like have been widely used. Especially in recent years, home video equipment has rapidly spread, and the growth of video tapes has been remarkable. Along with that, the characteristics required for video tapes are becoming severer year by year. For example, high image quality and high durability are increasingly demanded, and technical studies are being conducted. As a magnetic material for high-quality video tapes, a ferromagnetic material with a small particle size tends to be used for the purpose of low noise, but in recent years, by using a magnetic powder of fine particles, a video S / N
Has been dramatically improved to meet the needs of users.
高画質ビデオテープ用磁性材としては現在Co被着型γ‐
Fe2O3粒子を代表するCo含有γ‐Fe2O3（Co-γ‐Fe2O3）
が広く用いられている。この磁性材は分散性が良く高域
特性がすぐれているが、微粒子化に伴ない、問題点も生
じてきた。第一点は、微粒子化に伴ない、樹脂バインダ
ー中への磁性材の分散が難かしくなり、磁性塗膜中に、
磁性粒子が、詰まりにくくなる点である。そのため、テ
ープ磁気特性の１つである。最大残留磁束密度Brが低下
し、オーデイオ感度、クロマ出力等の低域特性が低下し
て、重要な特性である、C-S/Nが低下する。第２点は、
微粒子化に伴ない、磁性塗膜の光透過率が低下する点で
ある。VHS・ビデオデツキにおいては、テープエンドを
光の透過量で検知する。走行中の誤動作防止の為、テー
プの光透過量を少なくする必要がある。その対策とし
て、カーボン等非磁性、無機着色顔料粒子を増加する必
要があり、その面からも、電磁変換特性が不利になる。As a magnetic material for high-quality video tapes, Co-coated γ- is currently used.
Co-containing γ-Fe 2 O 3 (Co-γ-Fe 2 O 3 ) representing Fe 2 O 3 particles
Is widely used. This magnetic material has good dispersibility and excellent high frequency characteristics, but problems have arisen with the formation of fine particles. The first point is that as the particles become finer, it becomes difficult to disperse the magnetic material in the resin binder.
The point is that the magnetic particles are less likely to become clogged. Therefore, it is one of the magnetic properties of the tape. The maximum residual magnetic flux density Br decreases, the low-frequency characteristics such as audio sensitivity and chroma output decrease, and CS / N, which is an important characteristic, decreases. The second point is
This is the point that the light transmittance of the magnetic coating film decreases as the particles become finer. In VHS / video deck, the tape end is detected by the amount of light transmission. It is necessary to reduce the amount of light transmission of the tape to prevent malfunction during running. As a countermeasure, it is necessary to increase the number of non-magnetic, inorganic coloring pigment particles such as carbon, which is also disadvantageous in electromagnetic conversion characteristics.
本発明者らは磁性粒子を、微粒子にした場合でも低域特
性のすぐれたビデオテープを作るべく検討した結果、良
好な特性を得る方法を発明した。The present inventors have studied to make a video tape having excellent low-frequency characteristics even when the magnetic particles are made into fine particles, and as a result, invented a method for obtaining good characteristics.
本発明の目的は、電磁変換特性が良く、しかも光透過性
の低い磁気記録媒体、特にビデオテープ等の高密度記録
媒体を提供することにある。An object of the present invention is to provide a magnetic recording medium having good electromagnetic conversion characteristics and low light transmittance, particularly a high density recording medium such as a video tape.
本発明による磁気記録媒体は、磁性粒子を樹脂バインダ
ー中に分散した磁性層を、ポリエステルフイルム等のプ
ラスチツクベース上に形成してなるもので、強磁性粒子
として、BET値25m2/g以上のCo-γ‐Fe2O3粒子とBET値20
m2/g以上のCrO2粒子を、Co-γ‐Fe2O3粒子に対して、５
〜25wt％添加したことを特徴とする。The magnetic recording medium according to the present invention comprises a magnetic layer in which magnetic particles are dispersed in a resin binder, which is formed on a plastic base such as a polyester film.The ferromagnetic particles have a BET value of 25 m 2 / g or more. -γ-Fe 2 O 3 particles and BET value 20
CrO 2 particles of m 2 / g or more are added to Co-γ-Fe 2 O 3 particles in an amount of 5
It is characterized by the addition of ~ 25wt%.
本発明の磁気記録媒体はCo-γ‐Fe2O3粒子にCrO2粒子を
添加したため、残留磁束密度Brが向上し、低域特性が改
善される。また、透光性は黒色のCrO2を混合することに
より、大幅に低下し、従来のようなカーボンブラツクの
使用は必要でなくなるか、最低限の使用で済むことにな
る。In the magnetic recording medium of the present invention, CrO 2 particles are added to Co-γ-Fe 2 O 3 particles, so that the residual magnetic flux density Br is improved and the low frequency characteristics are improved. In addition, the translucency is significantly reduced by mixing black CrO 2 , and the conventional use of carbon black is not necessary or is minimal.
本発明は、Co-γ‐Fe2O3粒子を主たる成分として用い、
これにCrO2粒子を併用するものである。The present invention uses Co-γ-Fe 2 O 3 particles as a main component,
CrO 2 particles are used together with this.
Co-γ‐Fe2O3としては任意のCo含有型の粒子を用いうる
が、好ましくはCo被着型のものを用いる。高周波電磁変
換特性の面からはCo-γ‐Fe2O3の表面積はBET値25m2/g
以上のものを用いるべきである。一般にCo-γ‐Fe2O3の
分散性は良く、高域特性がすぐれているが、BET値が大
きくなると低BET値のものより分散が難しくなり、磁性
塗料中に詰まりにくくなり、低域の出力の低下と光透過
量の増加を生じる。As Co-γ-Fe 2 O 3 , any Co-containing particles can be used, but Co-adhered particles are preferably used. From the viewpoint of high frequency electromagnetic conversion characteristics, the surface area of Co-γ-Fe 2 O 3 has a BET value of 25 m 2 / g.
The above should be used. In general, Co-γ-Fe 2 O 3 has good dispersibility and excellent high-frequency characteristics, but when the BET value increases, it becomes more difficult to disperse than those with a low BET value, and it becomes less likely to become clogged in the magnetic paint, resulting in low frequencies. It causes a decrease in output and an increase in light transmission.
そこで、本発明ではBET値20m2/g以上のCrO2粒子をCo-γ
‐Fe2O3を基準として約５〜25重量％磁性塗料中に共存
させる。一般にCrO2はBrが高く、低域の出力が高く、電
気抵抗が低く、さらに、粒子の色が黒色である為光透過
量が少ないという利点がある。使用するCrO2はBET値が2
0m2/g以上のものを用いるべきである。BET値が小さいと
分散性は良くなるが高域特性に悪影響が出る。BET値が2
0m2/g以上の場合には、CrO2単独では分散し難いが、そ
の含有率を約25重量％以下に抑えることにより十分な分
散性を得ることができる。またその含有率を約５重量％
以上にすると光の透過率が大幅に低下し、カーボンブラ
ツクの使用が不要となるため、電磁特性が良くなる。特
に残留磁束密度、RF低域特性、カラーS/N比（C-S/N）、
クロマ出力、オーデイオ出力が改善される。Therefore, in the present invention, CrO 2 particles having a BET value of 20 m 2 / g or more are used as Co-γ
-Coexist in about 5 to 25% by weight based on Fe 2 O 3 in the magnetic paint. In general, CrO 2 has the advantages of high Br, high output in the low range, low electrical resistance, and low light transmission due to the black color of the particles. The CrO 2 used has a BET value of 2
You should use more than 0m 2 / g. When the BET value is small, the dispersibility is improved but the high frequency characteristics are adversely affected. BET value is 2
In the case of 0 m 2 / g or more, it is difficult to disperse CrO 2 alone, but sufficient dispersibility can be obtained by suppressing the content of CrO 2 to about 25% by weight or less. Moreover, the content rate is about 5% by weight.
With the above, the light transmittance is significantly reduced, and the use of carbon black is unnecessary, so that the electromagnetic characteristics are improved. Especially residual magnetic flux density, RF low frequency characteristics, color S / N ratio (CS / N),
The chroma output and audio output are improved.
本発明はこのようにCrO2粒子の分散性の悪さをCo-γ‐F
e2O3粒子と併用することで改善し、こうしてCrO2粒子の
長所を利用することによりCo-γ‐Fe2O3粒子の短所を補
つたものである。According to the present invention, the poor dispersibility of CrO 2 particles is
It is improved by using together with e 2 O 3 particles, and thus the disadvantages of Co-γ-Fe 2 O 3 particles are compensated by utilizing the advantages of CrO 2 particles.
下記組成比で材料を混合し、混合物を、ボールミルで充
分に分散したのち、ポリエステルフイルム塗布し、サン
プルを作成した。The materials were mixed in the following composition ratio, and the mixture was sufficiently dispersed by a ball mill and then coated on a polyester film to prepare a sample.
本発明に使用する樹脂バインダーは、特徴部分を構成す
るものではなく、従来より磁気記録媒体に使用されてい
る熱可塑性バインダー、熱硬化系バインダー、電子線硬
化系バインダー、紫外線硬化系バインダーなどの、全て
の樹脂バインダーが使用できる。特に、塩化ビニール、
酢酸ビニール共重合体を、ウレタン及びイソシアネート
を樹脂成分とする、熱硬化系バインダーが適している。
更に、磁性層の摩擦を低下させ、走行性を良好にする
為、潤滑剤として、炭素数12〜20の脂肪酸及び炭素数３
〜12の一価アルコールと前記脂肪酸とのエステルのう
ち、どちらか一方あるいは双方の混合物を使用すること
ができる。実施例１のサンプルをサンプルＣ−１、Ｃ−
２、Ｃ−３、比較例１のサンプルをサンプルＡ、比較例
２のサンプルをサンプルＢとする。表１に各サンプルの
測定結果を示す。 The resin binder used in the present invention does not constitute a characteristic part, such as a thermoplastic binder conventionally used in magnetic recording media, a thermosetting binder, an electron beam curing binder, an ultraviolet curing binder, and the like, All resin binders can be used. Especially vinyl chloride,
A thermosetting binder containing vinyl acetate copolymer and urethane and isocyanate as resin components is suitable.
Furthermore, in order to reduce the friction of the magnetic layer and improve the running property, fatty acids having 12 to 20 carbon atoms and 3 carbon atoms are used as lubricants.
Either one or a mixture of both of the esters of -12 monohydric alcohols and the above fatty acids can be used. The samples of Example 1 are sample C-1, C-
2, C-3, the sample of Comparative Example 1 is Sample A, and the sample of Comparative Example 2 is Sample B. Table 1 shows the measurement results of each sample.
〔本発明の作用効果、比較例との対比〕 BET30m2/gのCo-γ‐Fe2O3を使用した比較例１のサンプ
ル は、電気抵抗、光透過率の要求特性を満たす為に、カー
ボンを7wt％添加している。Co-γ‐Fe2O3の、分散性の
良さにより表面粗さRaが良く、エンベロープが良いにも
かかわらずBETが高いため、Br値が低く、クロマー出力
が低く、オーデイオ感度C-S/Nが低い。 [Effect of the present invention, comparison with comparative example] Sample of Comparative Example 1 using BET30m 2 / g Co-γ-Fe 2 O 3 Contains 7 wt% of carbon in order to satisfy the required characteristics of electric resistance and light transmittance. Co-γ-Fe 2 O 3 has good surface roughness Ra due to good dispersibility, and high BET despite good envelope, resulting in low Br value, low chroma output, and high CS / N audio sensitivity. Low.
一方、BET25m2/gのCrO2を使用した比較例２のサンプル
Ｂは、残留磁束密度Brが高く、クロマ出力、オーデイオ
出力などの低域出力が高い。クロマ出力は、C-S/Nに影
響し、クロマ出力の高いテープは、C-S/Nも高い値が得
られる。しかしながら、CrO2磁性粒子は分散性が悪い為
に、テープ表面粗さRaが大きく、エンベロープが悪い。
その影響でサンプルＢは、クロマ出力が高いというCrO2
粒子本来の特徴を生かせずC-S/Nは低い値にとどまつて
いる。On the other hand, the sample B of Comparative Example 2, which uses CrO 2 of BET 25 m 2 / g, has a high residual magnetic flux density Br and high low-frequency output such as chroma output and audio output. Chroma output affects CS / N, and tapes with high chroma output have high CS / N values. However, since the CrO 2 magnetic particles have poor dispersibility, the tape surface roughness Ra is large and the envelope is poor.
As a result, Sample B has a high chroma output, CrO 2
CS / N remains at a low value without utilizing the original characteristics of the particles.
このように、サンプルＡとサンプルＢは、一長一短があ
り、ビデオテープとしては、完全ではない。実施例１、
２、３のサンプルＣ−１、Ｃ−２、Ｃ−３は、BET値25m
2/gのCrO2はBET値30m2/gのCo-γ‐Fe2O3の粒子に対して
5wt％・15wt％・25wt％の割り合いで混合し、ビデオテ
ープとしたサンプルである。サンプルＡとサンプルＢの
長所を兼ね備えていることがわかる。すなわち、CrO2を
混合することにより、カーボンを使用せずに、電気抵抗
を下げることができ、光透過率を満足することができ
る。さらに、Brが大きく、クロマー出力が高い。又、Co
-γ‐Fe2O3本来の分散性の良さを失なつていない為テー
プ表面が平滑で、エンベロープが良く、C-S/Nが高い。
このようにサンプルＣ−１、Ｃ−２、Ｃ−３は、ビデオ
テープとして、バランスのとれたすぐれた特性を示して
おり、今後さらに進む、ビデオテープの高画質化に対し
て有効な手段になり得る方策である。As described above, sample A and sample B have advantages and disadvantages, and are not perfect as video tapes. Example 1,
A few samples C-1, C-2, and C-3 have a BET value of 25 m.
2 / g CrO 2 for particles of Co-γ-Fe 2 O 3 with BET value of 30 m 2 / g
This is a video tape sample that is mixed at a ratio of 5 wt%, 15 wt%, and 25 wt%. It can be seen that the sample A and the sample B have both advantages. That is, by mixing CrO 2 , the electric resistance can be lowered and the light transmittance can be satisfied without using carbon. In addition, Br is large and chroma output is high. Also, Co
-γ-Fe 2 O 3 Since the original good dispersibility is not lost, the tape surface is smooth, the envelope is good, and the CS / N is high.
As described above, the samples C-1, C-2, and C-3 have excellent balanced and excellent characteristics as video tapes, and are effective means for further improving the image quality of video tapes in the future. This is a possible strategy.
Claims (1)
した磁性塗料を、プラスチックベース上に塗布した磁気
記録媒体において、上記強磁性粒子が、BET値25m2/g以
上のCo-γ‐Fe2O3粒子と、BET値20m2/g以上のCrO2粒子
とからなり、CrO2粒子が、Co-γ‐Fe2O3粒子に対して5w
t％以上、25wt％以下含まれ、且つカーボンブラックが
含まれていないことを特徴とする、磁気記録媒体。1. A magnetic recording medium comprising a plastic base coated with a magnetic coating material containing ferromagnetic particles dispersed in a resin binder, wherein the ferromagnetic particles have a BET value of 25 m 2 / g or more. and Fe 2 O 3 particles composed of a BET value 20 m 2 / g or more CrO 2 particles, CrO 2 particles, 5w against Co-γ-Fe 2 O 3 particles
A magnetic recording medium containing t% or more and 25 wt% or less and not containing carbon black.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP60271374A JPH0746418B2 (en) | 1985-12-04 | 1985-12-04 | Magnetic recording medium |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP60271374A JPH0746418B2 (en) | 1985-12-04 | 1985-12-04 | Magnetic recording medium |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS62132230A JPS62132230A (en) | 1987-06-15 |
| JPH0746418B2 true JPH0746418B2 (en) | 1995-05-17 |
Family
ID=17499179
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP60271374A Expired - Lifetime JPH0746418B2 (en) | 1985-12-04 | 1985-12-04 | Magnetic recording medium |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0746418B2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH04184903A (en) * | 1990-11-19 | 1992-07-01 | Toda Kogyo Corp | Manufacture of magnetic particle power for magnetic recording |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0656653B2 (en) * | 1984-06-13 | 1994-07-27 | 日立マクセル株式会社 | Magnetic recording medium |
-
1985
- 1985-12-04 JP JP60271374A patent/JPH0746418B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPS62132230A (en) | 1987-06-15 |
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