JPS6332243B2 - - Google Patents
Info
- Publication number
- JPS6332243B2 JPS6332243B2 JP56159066A JP15906681A JPS6332243B2 JP S6332243 B2 JPS6332243 B2 JP S6332243B2 JP 56159066 A JP56159066 A JP 56159066A JP 15906681 A JP15906681 A JP 15906681A JP S6332243 B2 JPS6332243 B2 JP S6332243B2
- Authority
- JP
- Japan
- Prior art keywords
- feooh
- reaction
- nucleation
- amount
- crystals
- 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
Links
- 238000006243 chemical reaction Methods 0.000 claims description 39
- 229910006540 α-FeOOH Inorganic materials 0.000 claims description 29
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 claims description 26
- 239000013078 crystal Substances 0.000 claims description 23
- 230000006911 nucleation Effects 0.000 claims description 15
- 238000010899 nucleation Methods 0.000 claims description 15
- 238000000034 method Methods 0.000 claims description 13
- 229910002588 FeOOH Inorganic materials 0.000 claims description 11
- BAUYGSIQEAFULO-UHFFFAOYSA-L iron(2+) sulfate (anhydrous) Chemical compound [Fe+2].[O-]S([O-])(=O)=O BAUYGSIQEAFULO-UHFFFAOYSA-L 0.000 claims description 10
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 9
- 229910000147 aluminium phosphate Inorganic materials 0.000 claims description 8
- 150000003839 salts Chemical class 0.000 claims description 8
- 239000003513 alkali Substances 0.000 claims description 6
- 230000001590 oxidative effect Effects 0.000 claims description 6
- 239000007864 aqueous solution Substances 0.000 claims description 5
- 238000004519 manufacturing process Methods 0.000 claims description 5
- 229910052742 iron Inorganic materials 0.000 claims description 3
- 230000003472 neutralizing effect Effects 0.000 claims description 3
- 239000002245 particle Substances 0.000 description 14
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 12
- 235000011007 phosphoric acid Nutrition 0.000 description 12
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 6
- 229910001566 austenite Inorganic materials 0.000 description 6
- 238000007254 oxidation reaction Methods 0.000 description 5
- 239000012266 salt solution Substances 0.000 description 5
- 239000007788 liquid Substances 0.000 description 4
- 239000007800 oxidant agent Substances 0.000 description 4
- 230000003647 oxidation Effects 0.000 description 4
- 239000000843 powder Substances 0.000 description 4
- 239000002244 precipitate Substances 0.000 description 4
- 239000000243 solution Substances 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- ZWEHNKRNPOVVGH-UHFFFAOYSA-N 2-Butanone Chemical compound CCC(C)=O ZWEHNKRNPOVVGH-UHFFFAOYSA-N 0.000 description 3
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 3
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000001257 hydrogen Substances 0.000 description 3
- 229910052739 hydrogen Inorganic materials 0.000 description 3
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 239000012452 mother liquor Substances 0.000 description 3
- 229910006299 γ-FeOOH Inorganic materials 0.000 description 3
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 2
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 2
- UEZVMMHDMIWARA-UHFFFAOYSA-N Metaphosphoric acid Chemical compound OP(=O)=O UEZVMMHDMIWARA-UHFFFAOYSA-N 0.000 description 2
- 230000002378 acidificating effect Effects 0.000 description 2
- 238000007664 blowing Methods 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 238000011109 contamination Methods 0.000 description 2
- 238000007796 conventional method Methods 0.000 description 2
- 230000018044 dehydration Effects 0.000 description 2
- 238000006297 dehydration reaction Methods 0.000 description 2
- 239000011790 ferrous sulphate Substances 0.000 description 2
- 235000003891 ferrous sulphate Nutrition 0.000 description 2
- 238000001914 filtration Methods 0.000 description 2
- 229910021506 iron(II) hydroxide Inorganic materials 0.000 description 2
- 229910000359 iron(II) sulfate Inorganic materials 0.000 description 2
- SZVJSHCCFOBDDC-UHFFFAOYSA-N iron(II,III) oxide Inorganic materials O=[Fe]O[Fe]O[Fe]=O SZVJSHCCFOBDDC-UHFFFAOYSA-N 0.000 description 2
- NCNCGGDMXMBVIA-UHFFFAOYSA-L iron(ii) hydroxide Chemical compound [OH-].[OH-].[Fe+2] NCNCGGDMXMBVIA-UHFFFAOYSA-L 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000000691 measurement method Methods 0.000 description 2
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 2
- 229920000137 polyphosphoric acid Polymers 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- 230000035484 reaction time Effects 0.000 description 2
- 238000005406 washing Methods 0.000 description 2
- JLPULHDHAOZNQI-ZTIMHPMXSA-N 1-hexadecanoyl-2-(9Z,12Z-octadecadienoyl)-sn-glycero-3-phosphocholine Chemical compound CCCCCCCCCCCCCCCC(=O)OC[C@H](COP([O-])(=O)OCC[N+](C)(C)C)OC(=O)CCCCCCC\C=C/C\C=C/CCCCC JLPULHDHAOZNQI-ZTIMHPMXSA-N 0.000 description 1
- MQIUGAXCHLFZKX-UHFFFAOYSA-N Di-n-octyl phthalate Natural products CCCCCCCCOC(=O)C1=CC=CC=C1C(=O)OCCCCCCCC MQIUGAXCHLFZKX-UHFFFAOYSA-N 0.000 description 1
- 102000004190 Enzymes Human genes 0.000 description 1
- 108090000790 Enzymes Proteins 0.000 description 1
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 description 1
- 229910002651 NO3 Inorganic materials 0.000 description 1
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 description 1
- LZBCVRCTAYKYHR-UHFFFAOYSA-N acetic acid;chloroethene Chemical compound ClC=C.CC(O)=O LZBCVRCTAYKYHR-UHFFFAOYSA-N 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 150000007513 acids Chemical class 0.000 description 1
- 229910052783 alkali metal Inorganic materials 0.000 description 1
- 150000001340 alkali metals Chemical class 0.000 description 1
- 229910052784 alkaline earth metal Inorganic materials 0.000 description 1
- 150000001342 alkaline earth metals Chemical class 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- BJQHLKABXJIVAM-UHFFFAOYSA-N bis(2-ethylhexyl) phthalate Chemical compound CCCCC(CC)COC(=O)C1=CC=CC=C1C(=O)OCC(CC)CCCC BJQHLKABXJIVAM-UHFFFAOYSA-N 0.000 description 1
- 229910000019 calcium carbonate Inorganic materials 0.000 description 1
- 150000004649 carbonic acid derivatives Chemical class 0.000 description 1
- 229920006026 co-polymeric resin Polymers 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 229960002089 ferrous chloride Drugs 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 1
- 150000004679 hydroxides Chemical class 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- NMCUIPGRVMDVDB-UHFFFAOYSA-L iron dichloride Chemical compound Cl[Fe]Cl NMCUIPGRVMDVDB-UHFFFAOYSA-L 0.000 description 1
- 230000005415 magnetization Effects 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 235000010755 mineral Nutrition 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 238000006386 neutralization reaction Methods 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000003973 paint Substances 0.000 description 1
- 229940085991 phosphate ion Drugs 0.000 description 1
- 229920006267 polyester film Polymers 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 238000010298 pulverizing process Methods 0.000 description 1
- 238000010405 reoxidation reaction Methods 0.000 description 1
- KKCBUQHMOMHUOY-UHFFFAOYSA-N sodium oxide Chemical compound [O-2].[Na+].[Na+] KKCBUQHMOMHUOY-UHFFFAOYSA-N 0.000 description 1
- 229910001948 sodium oxide Inorganic materials 0.000 description 1
- 229940083466 soybean lecithin Drugs 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 239000004094 surface-active agent Substances 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
Classifications
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
- G11B5/62—Record carriers characterised by the selection of the material
- G11B5/68—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent
- G11B5/70—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer
- G11B5/706—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer characterised by the composition of the magnetic material
- G11B5/70626—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer characterised by the composition of the magnetic material containing non-metallic substances
- G11B5/70642—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer characterised by the composition of the magnetic material containing non-metallic substances iron oxides
- G11B5/70652—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer characterised by the composition of the magnetic material containing non-metallic substances iron oxides gamma - Fe2 O3
- G11B5/70663—Preparation processes specially adapted therefor, e.g. using stabilising agents
Landscapes
- Magnetic Record Carriers (AREA)
- Hard Magnetic Materials (AREA)
- Compounds Of Iron (AREA)
- Paints Or Removers (AREA)
Description
本発明は改良された針状α−FeOOHの製造方
法に関する。
α−FeOOHの製法は、大別して、酸性側で反
応を行なう方法と、アルカリ性側で反応を行なう
方法とがあり、α−FeOOHを工業的に安価に得
るためには酸性側での反応がより有利であるとさ
れている。この酸性側で反応を行なう方法につい
ても、種々の提案があり、例えば、特公昭55−
3295号公報には、水酸化第１鉄の沈澱をPH３程度
になるまで酸化しして核晶を生成させ、次いでリ
ン酸又はその塩の存在下にPH７程度になるまで酸
化して核晶を成長させα−FeOOHを得ることが
記載され、また特開昭55−149136号公報には、水
酸化第１鉄の沈澱を酸化してα−FeOOH、γ−
FeOOH或はそれらの混合物を主成分とする含水
酸化鉄を得るにあたつて、酸化反応の開始から終
るまでの大部分において反応液のPH値を5.5〜7.5
の間に維持することが記載されている。しかしな
がら、これらの方法で得られるα−FeOOHにつ
いても、粒度分布、、粒子形状性などでなお一層
の改良が望まれている。
本発明者等は、前記方法の改良について、特に
α−FeOOHの生成過程について種々検討を重ね
た結果グリーンラストの一定量が反応系内に常に
存在するようにすると望ましい効果をもたらすこ
と、グリーンラストの量は系内のPH値と一定の関
係にあることなどを見い出し、α−FeOOHの生
成反応において、α−FeOOH核晶生成反応終了
前からα−FeOOH核晶成長反応終了までの期間
ある特定のPHとすることによつて、粒度分布、粒
子形状性の改良された良質なα−FeOOHが製造
できることを確認して、本発明を完成した。
本発明は第１鉄塩水溶液をアルカリで部分中和
して鉄分の一部を沈殿させ、次に酸化してα−
FeOOH核晶を生成させ、その後中和、酸化して
該核晶を成長させて針状α−FeOOHを得る方法
において、(イ)該核晶生成反応を40℃〜85℃の温度
に維持しながらPHが4.5〜5.5になるまで酸化し、
(ロ)該核晶成長反応を温度40℃〜85℃及びPH4.5〜
5.5に維持しながら行ない、(ハ)該核晶生成反応及
び／又は該核晶成長反応において、リン酸或はこ
れらの水溶塩を存在させる、ことを特徴とする、
磁気記録材料用針状α−FeOOHの製造方法であ
る。
使用する第１鉄塩溶液としては、硫酸第１鉄、
硝酸第１鉄、塩化第１鉄などの鉱酸の第１鉄塩溶
液などがあり、工業的には硫酸第１鉄が好まし
い。アルカリとしては、アルカリ金属或はアルカ
リ土類金属の水酸化物、酸化物又は炭酸塩即ち、
水酸化ナトリウム、水酸化カリウム、酸化ナトリ
ウム、炭酸カルシウムなどが挙げられ、工業的に
は水酸化ナトリウム、水酸化カリウムが好まし
い。酸化剤としては、気体酸化剤、即ち空気、酸
素などが挙げられるが一般に空気が好適である。
本発明の方法においては、先づ第１鉄塩溶液を
アルカリで部分中和し、酸化して、液中のFe分
の一部をα−FeOOHの核晶にする。この核晶生
成反応開始時における第１鉄塩溶液の濃度は普通
30〜100ｇ／であり、PHは３程度である。アル
カリの添加量は、普通母液中のFeイオンを５〜
25ｇ／沈澱させるに必要な量であり、この添加
により系のPHは８程度まで引上げられる。この懸
濁液に酸化剤を導入して酸化し、水酸化物沈澱を
グリーンラスト経由α−FeOOHの核晶とする。
この間PHは々に低下するが、この段階の酸化を、
系のPHが4.5〜5.5の範囲の値になるように行な
う。このPHが低すぎると系内に必要な量のグリー
ンラストが存在しなくなり、α−FeOOH核晶の
表面状態が悪くなつて、枝分れを生じたり、好ま
しくない核発生を生じたりして、良好なα−
FeOOHがが得られなくなる。この系内における
グリーンラストの存在量は、普通α−FeOOH換
算量で１〜４ｇ／である。
反応温度は、通常40〜85℃、望ましくは40〜60
℃に維持し、反応時間はなるべく短時間に、例え
ば10〜100分程度になるように調節するのがよい。
反応温度が上記範囲より低くなりすぎるとγ−
FeOOHの生成量が多くなり、本発明の効果が得
られ難い。またγ−FeOOHの混入を防止する上
からも中和沈澱率を70％以下とするのがよい。得
られる核晶はBET比表面積が例えば50〜100m2／
ｇ程度のものであることが望ましい。
また、この核晶生成反応において、生成α−
FeOOH核晶量に対しｐ換算で0.05〜0.6重量％、
望ましくは0.1〜0.4重量％のオルトリン酸、メタ
リン酸、ポリリン酸などのリン酸或はこれらの水
溶性塩を存在させるのが好ましい。このリン酸又
はその塩の添加は、枝分れの発生を防止し、粒度
分布の拡がりを抑える効果をもたらす。
上述の核晶生成反応の終つたPH4.5〜5.5の液
は、α−FeOOH核晶と少量のグリーンラストと
の懸濁した第１鉄塩溶液であり、次いでこの液
に、アルカリを添加しながら酸化して、核晶を成
長させ、所望のα−FeOOHを得る。この核晶成
長反応において、開始から終了までPHが4.5〜5.5
範囲内のほぼ一定の値を維持するように、中和、
酸化速度を調節し反応を行なうことが重要であ
る。このPHが低すぎると、系内に必要な量のグリ
ーンラストが存在しなくなり、α−FeOOH核晶
の表面状態が悪化して枝分れを生じたり、好まし
くない新しい核発生が起つたりして良質なα−
FeOOHが得られなくなり、一方このPHが高すぎ
ると、系内にグリーンラストの量が多くなりすぎ
て母液粘度が高くなり、不均質反応を生じ枝分れ
の発生をまねき、またγ−FeOOH及びマグネタ
イトの混入がさけられず、この場合も良質なα−
FeOOHが得られない。この反応においてPHの変
動は極力低く抑える方がよく、例えば±0.1程度
に抑えるのが好ましい。こ系内におけるグリーン
ラストの存在量は普通α−FeOOH換算量で１〜
４ｇ／ある。
この核晶成長反応において、反応温度は40〜85
℃、望ましくは40〜60℃に維持し、核晶の成長速
度は１〜15ｇ／／時程度に調節するのが望まし
く、またあらかじめ母液の濃度、核晶の生成量を
調節するか、核晶生成後に第１鉄塩を補給して成
長反応を行なうか、成長反応を適当に打ち切るか
して、α−FeOOH核晶を該核晶の重量による成
長倍率が1.5〜６になるようにするのが好ましい。
得られるα−FeOOHのBET比の表面積が、例え
ば30〜50m2／ｇ程度のものであることが望まし
い。
また、この核晶成長反応において、良質のα−
FeOOHを得るため、かつ高温、例えば70℃以上
での反応における粒状マグネタイトの生成防止の
ためには、生成するα−FeOOH全量基準ｐ換算
量で0.1〜0.8重量％となるようにオルトリン酸、
メタリン酸、ポリリン酸などのリン酸或はこれら
の水溶性塩を添加するのが好ましい。前工程、即
ち核晶生成反応中に添加されたリン酸又はその塩
は、核晶中に取りこまれたり、その表面に強く吸
着されたりして、遊離した状態では液中に残存し
ないので、核晶成長時にリン酸又はその塩を存在
させるためには、この段階で新たに添加する必要
がある。
本発明方法は、前述した通り常に4.5以上のPH
を維持し、グリーンラストの存在する系で反応を
行なうことを特徴としており、気体酸化剤の利用
率は100％に近い。従つて液を通過するガス量を
最少限に留めることができ、持ち出し熱エネルギ
ーが少なくできるという工業的利点を備えてい
る。
本発明方法によつて得られるα−FeOOHは、
粒度分布がシヤープで、枝分れが少なくかつ良好
な軸比を有するものであり、さらにこれにより誘
導されるγ−Fe2O3及びこれより製作した磁気テ
ープは良好な磁気特性を有するものである。
α−FeOOHは、通常の過、水洗、乾燥及び
粉砕を経て、α−FeOOH粉末として得られる。
このα−FeOOH粉末から通常の方法によりγ−
Fe2O3を得ることができる。すなわち、まず、
300〜700℃の温度において空気中で脱水し、次い
でこの脱水化物を300〜500℃の温度において水素
又は水蒸気を含む水素で還元してFe3O4を得、さ
らにこのFe3O4を200〜400℃の温度において酵素
又は空気で酸化することによりγ−Fe2O3とする
ことができる。
以下に実施例及び比較例によつて本発明を説明
する。
実施例 １
空気吹込み管と撹拌器を備えた反応器に、3800
ｇのFeSO4を含む水溶液20を入れ、50℃に昇温
し、NaOH水溶液（濃度200ｇ／）2.14を撹
拌下に加え（沈殿Fe15ｇ／）、この中へオルト
リン酸を遊離リン酸イオンのＰ換算量で核晶沈殿
物に対し0.2重量％添加し、600／時間の速度で
空気を吹き込み、50℃で50分間反応させてα−
FeOOH核晶を得た（核晶生成反応終了前のPH
5.0）。
さらに、66／時間の速度で空気を吹き込みな
がら、NaOH水溶液（濃度200ｇ／）3.15を
徐々に加えて、PHを5.3に維持し50℃で3.5時間反
応させ（このときの核晶の成長速度は約10ｇ／
／時間及びグリーンラストは約2.5ｇ／であ
つた）、核晶を約2.5倍に成長させた。このものの
BET比表面積は40m2／ｇであつた。なお、この
反応における空気利用率は95％以上であつた。
上記反応で得られたα−FeOOHは、通常の
過、水洗、乾燥及び粉砕を経て粉末を得、サンプ
ルＡとした。なお、グリーンラストの量は、液を
空気酸化してPHが3.5まで下つたときのα−
FeOOHの増量分を測定し、それをグリーンラス
ト量とした。
実施例 ２
下表第１−１及び１−２表に示すように、実施
例１において、核晶生成反応時にオルトリン酸を
添加しないこと及び反応時間を80分とすること、
核晶成長反応時にオルトリン酸を遊離リン酸イオ
ンのＰ換算量で生成する全α−FeOOH沈殿物に
対し0.2重量％添加すること及び該成長反応温度
を70℃に維持すること以外は同様に処理してサン
プルＢを得た。
The present invention relates to an improved method for producing acicular α-FeOOH. The production method for α-FeOOH can be roughly divided into two methods: one in which the reaction is carried out on the acidic side, and one in which the reaction is carried out in the alkaline side. It is said to be advantageous. There are various proposals regarding the method of carrying out the reaction on the acidic side, for example,
Publication No. 3295 discloses that a precipitate of ferrous hydroxide is oxidized to a pH of about 3 to generate nucleus crystals, and then oxidized to a pH of about 7 in the presence of phosphoric acid or its salt to generate nucleic crystals. It is described that α-FeOOH is obtained by growing α-FeOOH, and in Japanese Patent Application Laid-open No. 149136/1989, α-FeOOH and γ-FeOOH are obtained by oxidizing the precipitate of ferrous hydroxide.
When obtaining hydrated iron oxide mainly composed of FeOOH or a mixture thereof, the PH value of the reaction solution is maintained at 5.5 to 7.5 during most of the oxidation reaction from the start to the end.
It is stated that it should be maintained between However, even for α-FeOOH obtained by these methods, further improvements in particle size distribution, particle shape, etc. are desired. The present inventors have conducted various studies regarding the improvement of the above-mentioned method, particularly regarding the production process of α-FeOOH. As a result, the present inventors have found that a desired effect is brought about when a certain amount of Green Rust is always present in the reaction system. It was discovered that the amount of The present invention was completed by confirming that high-quality α-FeOOH with improved particle size distribution and shape can be produced by adjusting the pH to . The present invention involves partially neutralizing a ferrous salt aqueous solution with an alkali to precipitate a part of the iron content, and then oxidizing it to α-
In the method of generating FeOOH nucleus crystals and then neutralizing and oxidizing them to grow the nucleus crystals to obtain acicular α-FeOOH, (a) maintaining the nucleation reaction at a temperature of 40°C to 85°C; while oxidizing until the pH becomes 4.5 to 5.5,
(b) The nucleus crystal growth reaction is carried out at a temperature of 40°C to 85°C and a pH of 4.5 to
5.5, and (c) phosphoric acid or an aqueous salt thereof is present in the nucleation reaction and/or the nucleation growth reaction.
This is a method for producing acicular α-FeOOH for magnetic recording materials. The ferrous salt solutions used include ferrous sulfate,
Examples include ferrous salt solutions of mineral acids such as ferrous nitrate and ferrous chloride, and ferrous sulfate is preferred industrially. As the alkali, hydroxides, oxides or carbonates of alkali metals or alkaline earth metals, ie,
Examples include sodium hydroxide, potassium hydroxide, sodium oxide, and calcium carbonate, with sodium hydroxide and potassium hydroxide being preferred industrially. Examples of the oxidizing agent include gaseous oxidizing agents, ie, air, oxygen, etc., with air generally being preferred. In the method of the present invention, a ferrous salt solution is first partially neutralized with an alkali and oxidized to convert a portion of the Fe content in the solution into α-FeOOH nucleus crystals. The concentration of the ferrous salt solution at the start of this nucleation reaction is normal.
The amount is 30 to 100g/, and the pH is about 3. The amount of alkali added is usually 5 to 5% Fe ions in the mother liquor.
The amount is 25g/necessary for precipitation, and this addition raises the pH of the system to about 8. An oxidizing agent is introduced into this suspension to oxidize it, and the hydroxide precipitate is used as a nucleus crystal of α-FeOOH via green last.
During this period, the pH gradually decreases, but the oxidation at this stage
Do this so that the pH of the system is within the range of 4.5 to 5.5. If this pH is too low, the necessary amount of green last will not exist in the system, and the surface condition of α-FeOOH nuclei will deteriorate, resulting in branching and undesirable nucleation. Good α-
FeOOH cannot be obtained. The amount of green rust present in this system is usually 1 to 4 g/in terms of α-FeOOH. The reaction temperature is usually 40 to 85℃, preferably 40 to 60℃.
The reaction time is preferably adjusted to be as short as possible, for example, about 10 to 100 minutes.
If the reaction temperature becomes too low than the above range, γ-
The amount of FeOOH produced increases, making it difficult to obtain the effects of the present invention. Also, in order to prevent the contamination of γ-FeOOH, the neutralization precipitation rate is preferably 70% or less. The resulting nucleus has a BET specific surface area of, for example, 50 to 100 m 2 /
It is desirable that the thickness be about 100 g. In addition, in this nucleation reaction, the product α-
0.05 to 0.6% by weight in terms of p based on the amount of FeOOH nuclei,
Preferably, 0.1 to 0.4% by weight of phosphoric acid such as orthophosphoric acid, metaphosphoric acid, polyphosphoric acid, or a water-soluble salt thereof is present. The addition of phosphoric acid or its salt has the effect of preventing the occurrence of branching and suppressing the spread of particle size distribution. The liquid with a pH of 4.5 to 5.5 after the above-mentioned nucleation reaction is a ferrous salt solution in which α-FeOOH nucleus crystals and a small amount of green rust are suspended.Next, an alkali is added to this liquid. oxidation while growing the core crystals to obtain the desired α-FeOOH. In this nucleus crystal growth reaction, the pH is 4.5 to 5.5 from start to finish.
Neutralize, so as to maintain approximately constant values within a range.
It is important to control the oxidation rate to conduct the reaction. If this pH is too low, the necessary amount of green last will not exist in the system, and the surface condition of α-FeOOH nuclei will deteriorate, resulting in branching and undesirable new nucleation. High quality α-
FeOOH cannot be obtained. On the other hand, if this pH is too high, the amount of green last will be too large in the system, increasing the viscosity of the mother liquor, causing a heterogeneous reaction, leading to the occurrence of branching, and γ-FeOOH and Contamination with magnetite cannot be avoided, and in this case also high quality α-
FeOOH cannot be obtained. In this reaction, it is better to keep the PH fluctuation as low as possible, for example to about ±0.1. The amount of green last in this system is usually 1 to 1 in terms of α-FeOOH.
There is 4g/. In this nucleus crystal growth reaction, the reaction temperature is 40 to 85
℃, preferably 40 to 60℃, and the growth rate of the nucleus crystals is desirably adjusted to about 1 to 15 g/hour.Also, it is preferable to adjust the concentration of the mother liquor and the amount of nuclei crystals produced in advance, or to After generation, the growth reaction is carried out by replenishing ferrous salt, or the growth reaction is appropriately stopped, so that the growth rate of the α-FeOOH nuclei is 1.5 to 6 based on the weight of the nuclei. is preferred.
It is desirable that the BET ratio surface area of the obtained α-FeOOH is, for example, about 30 to 50 m 2 /g. In addition, in this nucleus crystal growth reaction, high quality α-
In order to obtain FeOOH and to prevent the formation of granular magnetite in the reaction at high temperatures, for example, 70°C or higher, orthophosphoric acid is
It is preferable to add phosphoric acid such as metaphosphoric acid and polyphosphoric acid, or a water-soluble salt thereof. Phosphoric acid or its salt added during the previous step, that is, the nucleation reaction, is incorporated into the nucleation crystal or strongly adsorbed to its surface, and does not remain in the liquid in a free state. In order to have phosphoric acid or its salt present during the growth of nuclei, it is necessary to newly add it at this stage. As mentioned above, the method of the present invention always has a pH of 4.5 or higher.
The system is characterized by maintaining the green rust and performing the reaction in a system where green last exists, and the utilization rate of the gaseous oxidant is close to 100%. Therefore, the amount of gas passing through the liquid can be kept to a minimum, which has the industrial advantage of reducing the amount of heat energy taken out. α-FeOOH obtained by the method of the present invention is
It has a sharp particle size distribution, less branching, and a good axial ratio, and furthermore, the γ-Fe 2 O 3 induced by this and the magnetic tape made from it have good magnetic properties. be. α-FeOOH is obtained as α-FeOOH powder through conventional filtering, water washing, drying and pulverization.
From this α-FeOOH powder, γ-
Fe 2 O 3 can be obtained. That is, first,
Fe 3 O 4 is obtained by dehydration in air at a temperature of 300 to 700 °C, and then reduction of this dehydrate with hydrogen or hydrogen containing water vapor at a temperature of 300 to 500 °C, which is further reduced to 200 ° C. γ-Fe 2 O 3 can be obtained by oxidation with enzymes or air at temperatures of ~400°C. The present invention will be explained below with reference to Examples and Comparative Examples. Example 1 A reactor equipped with an air blowing tube and a stirrer was equipped with a 3800
Pour 20 g of an aqueous solution containing 20 g of FeSO 4 into the solution, raise the temperature to 50°C, add 2.14 g of NaOH aqueous solution (concentration 200 g/) with stirring (precipitated Fe 15 g/), and add orthophosphoric acid into the solution to calculate P conversion of free phosphate ion. The α-
Obtained FeOOH nuclei (PH before completion of nucleation reaction)
5.0). Furthermore, while blowing air at a rate of 66/hour, 3.15 NaOH aqueous solution (concentration 200 g/hour) was gradually added, the pH was maintained at 5.3, and the reaction was carried out at 50°C for 3.5 hours (the growth rate of the nucleus crystals at this time was Approximately 10g/
/hour and green last was about 2.5 g/hour), the nucleus crystals grew about 2.5 times. of this
The BET specific surface area was 40 m 2 /g. Note that the air utilization rate in this reaction was 95% or more. The α-FeOOH obtained in the above reaction was filtered, washed with water, dried and pulverized to obtain a powder, which was designated as Sample A. In addition, the amount of green last is α-
The increased amount of FeOOH was measured and was defined as the amount of green last. Example 2 As shown in Tables 1-1 and 1-2 below, in Example 1, no orthophosphoric acid was added during the nucleation reaction and the reaction time was 80 minutes.
Same treatment except that 0.2% by weight of orthophosphoric acid was added to the total α-FeOOH precipitate generated in P equivalent amount of free phosphate ions during the nucleic growth reaction, and the growth reaction temperature was maintained at 70°C. Sample B was obtained.
【表】【table】
【表】
比較例 １〜３
下表第２−１及び２−２に示す条件を代える以
外は前記実施例１の場合と同様にして、それぞれ
のサンプルＣ、Ｄ、Ｅ及びＦを得た。[Table] Comparative Examples 1 to 3 Samples C, D, E, and F were obtained in the same manner as in Example 1 except that the conditions shown in Tables 2-1 and 2-2 below were changed.
【表】【table】
【表】
上記の反応で得られたサンプルＡ〜Ｆについ
て、
通常の方法により軸比（Ｌ／Ｗ）を測定し、さ
らに下記の方法により粒度分布（σL/L）及び枝分
れ発生率について測定し、第３表の結果を得た。
粒度分布（σL/L）の測定方法
よく分散させたα−FeOOHを試料とし、電子
顕微鏡により3000個以上の粒子の長軸粒子径を読
みとり、その算術平均軸長（μ）と標準偏差σL
（μ）を決め、下記の式に従つて粒度分布を求め
る。
粒度分布＝（σL/L）
枝分れの測定方法
粒度分布測定と同様な方法で、粒子の中に枝状
晶のあるものの個数ndと、測定総個数ｎを求め、
下記の式に従つて枝分れ率を算出する。
枝分れ率（％）＝nd／ｎ×100[Table] For samples A to F obtained in the above reaction, the axial ratio (L/W) was measured by the usual method, and the particle size distribution (σ L/L ) and branching incidence were determined by the following method. The results shown in Table 3 were obtained. Measurement method of particle size distribution (σ L/L ) Using well-dispersed α-FeOOH as a sample, read the long axis particle diameter of more than 3000 particles using an electron microscope, and calculate the arithmetic mean axis length (μ) and standard deviation σ L
(μ) and obtain the particle size distribution according to the formula below. Particle size distribution = (σ L/L ) Branching measurement method Using the same method as the particle size distribution measurement, find the number nd of particles with branched crystals in the particles and the total number n measured.
The branching rate is calculated according to the formula below. Branching rate (%) = nd/n×100
【表】
前記実施例及び比較例で得られたサンプルＡ〜
Ｆについて、過、水洗後、通常の方法により脱
水（空気中、650℃）、還元（水蒸気を含む水素
中、420℃）及び再酸化（空気中、280℃）を行な
い、γ−Fe2O3を得た。各々のγ−Fe2O3につい
て、通常の方法により保磁力（Hc）を測定し、
さらに各々のγ−Fe2O3について、下記の配合割
合に従つて、配合物を調製し、ボールミルで混練
して、磁性塗料を製造した。
(1) γ−Fe2O3粉末 100重量部
(2) 大豆レシチン 1.6 〃
(3) 界面活性剤 ４ 〃
(4) 酢ビー塩ビ共重合樹脂 10.5 〃
(5) ジオクチルフタレート ４ 〃
(6) メチルエチルケトン 84 〃
(7) トルエン 93 〃
次いで、各々の磁性塗料をポリエステルフイル
ムに通常の方法により塗布、配向した後乾燥し
て、約7μ厚の磁性塗膜を有する磁気記録体を作
成した。これら磁気記録体について、通常の方法
により、保磁力（Hc）、飽和磁化（Bm）、角形
比（Br／Bm）、配向性（OR）．及び反転磁界分
布（SFD）を測定し、第４表の結果を得た。[Table] Samples A~ obtained in the above Examples and Comparative Examples
For F, after filtering and washing with water, dehydration (in air, 650°C), reduction (in hydrogen containing steam, 420°C), and reoxidation (in air, 280°C) were performed to obtain γ-Fe 2 O. Got 3 . For each γ-Fe 2 O 3 , measure the coercive force (Hc) by the usual method,
Further, for each γ-Fe 2 O 3 , a mixture was prepared according to the following blending ratio, and the mixture was kneaded in a ball mill to produce a magnetic paint. (1) γ-Fe 2 O 3 powder 100 parts by weight (2) Soybean lecithin 1.6 〃 (3) Surfactant 4 〃 (4) Acetic acid vinyl chloride copolymer resin 10.5 〃 (5) Dioctyl phthalate 4 〃 (6) Methyl ethyl ketone 84 〃 (7) Toluene 93 〃 Next, each magnetic coating material was applied to a polyester film using a conventional method, oriented and dried, thereby producing a magnetic recording medium having a magnetic coating film approximately 7 μ thick. For these magnetic recording bodies, coercive force (Hc), saturation magnetization (Bm), squareness ratio (Br/Bm), and orientation (OR) were measured using conventional methods. and switching field distribution (SFD) were measured, and the results shown in Table 4 were obtained.
【表】【table】
Claims (1)
分の一部を沈殿させ、次に酸化してα−FeOOH
核晶を生成させ、その後、中和、酸化して該核晶
を成長させて針状α−FeOOHを得る方法におい
て、 (イ) 該核晶生成反応を40℃〜85℃の温度に維持し
ながらPHが4.5〜5.5になるまで酸化し、 (ロ) 該核晶成長反応を温度40℃〜85℃及びPH4.5
〜5.5に維持しながら行ない、 (ハ) 該核晶生成反応及び／又は該核晶成長反応に
おいて、リン酸或はこれらの水溶性塩を存在さ
せる、 ことを特徴とする、磁気記録材料用針状α−
FeOOHの製造方法。[Claims] 1. Partially neutralize a ferrous salt aqueous solution with an alkali to precipitate a part of the iron content, and then oxidize it to form α-FeOOH.
In the method of generating nucleation crystals, and then neutralizing and oxidizing the nucleation crystals to grow the acicular α-FeOOH, (a) maintaining the nucleation reaction at a temperature of 40°C to 85°C; (b) The nucleus crystal growth reaction is carried out at a temperature of 40°C to 85°C and a pH of 4.5.
5.5, and (c) phosphoric acid or a water-soluble salt thereof is present in the nucleic crystal generation reaction and/or the nucleic crystal growth reaction. State α−
Production method of FeOOH.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP56159066A JPS5860505A (en) | 1981-10-06 | 1981-10-06 | Method of manufacturing needle-like alpha-feooh for magnetic recoding material |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP56159066A JPS5860505A (en) | 1981-10-06 | 1981-10-06 | Method of manufacturing needle-like alpha-feooh for magnetic recoding material |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5860505A JPS5860505A (en) | 1983-04-11 |
| JPS6332243B2 true JPS6332243B2 (en) | 1988-06-29 |
Family
ID=15685464
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP56159066A Granted JPS5860505A (en) | 1981-10-06 | 1981-10-06 | Method of manufacturing needle-like alpha-feooh for magnetic recoding material |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5860505A (en) |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5051999A (en) * | 1973-04-27 | 1975-05-09 | ||
| JPS553295A (en) * | 1978-06-20 | 1980-01-11 | Cselt Centro Studi Lab Telecom | Wavelength dividing transmitter |
-
1981
- 1981-10-06 JP JP56159066A patent/JPS5860505A/en active Granted
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5051999A (en) * | 1973-04-27 | 1975-05-09 | ||
| JPS553295A (en) * | 1978-06-20 | 1980-01-11 | Cselt Centro Studi Lab Telecom | Wavelength dividing transmitter |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5860505A (en) | 1983-04-11 |
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