JP3620622B2 - Aqueous suspension of lipidocrocite particles - Google Patents

Description

【０１３７】
【表２】

【０１３８】
＜核晶存在下でのレピドクロサイト粒子粉末の製造＞
実施例４
先ず、下記のＢ溶液及びＣ溶液を作製し、３５℃の別々のチャンバーに入れた。
【０１３９】
Ｂ溶液：５．６８ｇのリン酸水素二ナトリウムを３００ｍｌの水に溶解したリン酸水素二ナトリウム溶液に、１．８３４ｍｏｌ／ｌの硫酸第一鉄水溶液１０９１ｍｌを添加、混合し、更に水を加えて容量１５００ｍｌとした混合溶液。
【０１４０】
Ｃ溶液：２．９８ｇのリン酸水素二ナトリウムを１５０ｍｌの水に溶解したリン酸水素二ナトリウムに、１．８３４ｍｏｌ／ｌの硫酸第一鉄水溶液５７２ｍｌを添加、混合し、更に水を加えて容量１０００ｍｌとした混合溶液。
【０１４１】
次に、核晶粒子の存在下でレピドクロサイト粒子粉末の生成反応を行う。
【０１４２】
実効容積５ｌの気泡塔（リアクター）に投入した水２０００ｍｌを加熱して３５℃とした後、１０ｌ／ｍｉｎの速度で空気を通気して攪拌しながら、あらかじめ３５℃で３０分間熟成した上記Ｃ溶液を気泡塔に添加し、引き続き５分間通気攪拌を行った。
【０１４３】
次に、別に準備した３５℃のＮａＯＨ水溶液（１８．４ＮのＮａＯＨ水溶液９１ｍｌを水に稀釈して５００ｍｌとし、Ｃ溶液に含まれるＦｅに対して０．８当量に相当する水溶液とした。）を気泡塔に少しづつ添加し、添加終了後、さらに５分間、１０ｌ／ｍｉｎの速度で空気を通気して攪拌を行い、核晶粒子の生成反応を行った。
【０１４４】
引き続き、１０ｌ／ｍｉｎの速度で空気を通気して攪拌しながら、４０℃に加熱昇温し、次いで、４．５ＮのＮａＯＨ溶液を少し加えてｐＨ値が８に調整した。ｐＨ値の調整を完了した後、直ちに３５℃で３０分間熟成した上記３５℃のＢ溶液を気泡塔内に２５ｍｌ／ｍｉｎの速度で投入を開始し、６０分間で投入を継続した。Ｂ溶液投入中は、気泡塔内の温度を４０℃にコントロールするとともに、ＮａＯＨタンクから４．５ＮのＮａＯＨ水溶液を間歇的に添加して反応スラリーのｐＨ値を常時８程度に調整した。Ｂ溶液の投入が終了した後も、引き続き、空気を通気しながら、温度を４０℃、ｐＨ値を８に維持した。反応開始後８．３時間後に橙色沈澱を得た。
【０１４５】
得られた橙色沈澱を常法により濾過、水洗した後、８０℃で２４時間乾燥して乾燥物を得た。収率は６．５３ｋｇ／ｍ^３ ・時間であった。この乾燥物は、Ｘ線回折の結果、レピドクロサイト粒子粉末のみが認められた。このレピドクロサイト粒子粉末は、電子顕微鏡観察の結果、直方体状を呈した粒子であり、短軸径が０．０４５μｍ、長軸径が０．０９０μｍ、厚みが０．０１７μｍであって、長軸径：短軸径は２．０：１であった。長軸径の幾何標準偏差値はσｇ＝１．３２であり、粒度分布がより優れたものであった。また、。可溶性ＳＯ_４ は９０ｐｐｍであった。
【０１４６】
実施例５〜７、比較例８
核晶の種類及び量、第一鉄塩水溶液の濃度及び量、リン酸化合物やクエン酸化合物の種類及び量、アルカリ水溶液の種類及び濃度、原料の混合方法並びに混合時及び反応時のｐＨ値及び温度を種々変化させた以外は、実施例４と同様にして生成反応物を得た。
【０１４７】
実施例５〜７及び比較例８で得られた粒子は、いずれもＸ線回折の結果、レピドクロサイト粒子粉末のみからなることが認められた。
【０１４８】
実施例６で得られた反応生成物のＸ線回折図を図７に、電子顕微鏡写真（×３００００）を図８に示す。図７中、ピークＡはレピドクロサイトであり、レピドクロサイト粒子粉末のみからなることが認められた。
この時の主要製造条件を表３に、諸特性を表４に示す。
【０１４９】
【表３】

【０１５０】
【表４】

【０１５１】
＜レピドクロサイト粒子粉末の表面被覆処理＞
実施例８〜１６
表５及び表６に示す条件によりレピドクロサイト粒子の表面にＡｌ化合物、Ｓｉ化合物及び／又は界面活性剤による表面被覆処理を行った。
この時の主要製造条件及び諸特性を表５及び表６に示した。
【０１５２】
【表５】

【０１５３】
【表６】

【０１５４】
＜レピドクロサイト粒子の水性懸濁液の製造＞
実施例１７〜３２、比較例９〜１８
粒子粉末の種類、添加量、界面活性剤の種類を種々変化させた以外は前記発明の実施の形態と同様にして水性懸濁液を得た。その条件及び諸特性を表７及び表８に示した。
【０１５５】
【表７】

【０１５６】
【表８】

【０１５７】
＜水系塗料の製造＞
使用例１〜４、比較使用例１〜３
水性懸濁液の種類を種々変化させた以外は、前記発明の実施の形態と同様にして水系塗料を得た。
この時の主要製造条件及び諸特性を表９に示す。
【０１５８】
【表９】

【０１５９】
【発明の効果】
本発明に係るレピドクロサイト粒子の水性懸濁液は、分散しているレピドクロサイト粒子がかまぼこ板状（直方体状）を呈しており、難溶性含硫鉄塩が少ないことに起因して個々の粒子がバラバラであるので分散性が優れており、その粒子形状に起因して着色力及び隠蔽力が優れているので、均一分散性と分散安定性に優れた水性懸濁液タイプの橙色着色材として、水系塗料、水系印刷インキ、水系セメント着色剤及び水系化粧品に好適に使用でき、また、高濃度の水性懸濁液として、鋼板圧延用水系潤滑剤として好適に使用できる。
【図面の簡単な説明】
【図１】発明の実施の形態で得られた直方体状を呈したレピドクロサイト粒子粉末のＸ線回折図である。
【図２】発明の実施の形態で得られた直方体状を呈したレピドクロサイト粒子粉末の粒子構造を示す電子顕微鏡写真（×３００００）である。
【図３】比較例２で得られた反応生成物のＸ線回折図である。
【図４】比較例２得られた反応生成物の粒子構造を示す電子顕微鏡写真（×３００００）である。
【図５】比較例７で得られた反応生成物のＸ線回折図である。
【図６】比較例７得られた反応生成物の粒子構造を示す電子顕微鏡写真（×３００００）である。
【図７】実施例６で得られた直方体状を呈したレピドクロサイト粒子粉末のＸ線回折図である。
【図８】実施例６で得られた直方体状を呈したレピドクロサイト粒子粉末の粒子構造を示す電子顕微鏡写真（×３００００）である。[0001]
BACKGROUND OF THE INVENTION
The present invention has a kamaboko plate shape (cuboid shape) and a repicrocrosite particle powder in which individual particles are dispersed in an aqueous medium and is excellent in uniform dispersibility and dispersion stability. It relates to an aqueous suspension of docrosite particles.
[0002]
The main uses of aqueous suspensions of lipidoclosite particles according to the present invention are water-based paints, water-based printing inks, water-based cement colorants, water-based cosmetics, and water-based lubricants for rolling steel sheets.
[0003]
[Prior art]
In recent years, from the viewpoint of environmental problems, as seen in water-based paints, water-based printing inks, water-based cement colorants, water-based cosmetics, water-based lubricants for rolling steel sheets, etc., there is little air pollution, which is effective for resource and energy saving. Various products in which powder is dispersed in an aqueous medium that is easier to handle than solvent-based paints and that is free from fire hazards and can be used with peace of mind from the viewpoint of hygiene are being used.
[0004]
In each of the above applications, it is better to prepare and place an aqueous suspension in which the powder is dispersed in the aqueous medium in advance than to disperse the powder in the aqueous medium at the time of use. This is industrially advantageous because it can be used as a necessary concentration by diluting it according to the use.
[0005]
Typical powders to be dispersed in the aqueous suspension are organic pigments and inorganic pigments, but organic pigments are generally expensive, while inorganic pigments containing heavy metals such as lead and chromium are toxic. Therefore, there is a demand for inorganic pigments that are inexpensive and non-toxic for each of the above applications.
[0006]
As inorganic pigments that do not contain harmful heavy metals such as lead and chromium, pigments composed of iron oxide particles and hydrous iron oxide particles are known, are stable against oxidation by oxygen in the air, are inexpensive and harmless. It is used in various fields including the above-mentioned applications because it has excellent safety such as and has various hues.
[0007]
Conventionally, as an aqueous suspension in which iron oxide particle powder or hydrous iron oxide particle powder is dispersed in an aqueous medium, the dispersion is stabilized by adding a phosphate compound to the aqueous suspension of α-FeOOH particle powder. High concentration aqueous suspension of formed α-FeOOH particles (Japanese Patent Laid-Open No. 7-90292), Fe₃O₄Lubricant obtained by kneading particle powder, refractory component, binder and water (Japanese Patent No. 2556142), Fe₂O₃Particle powder or Fe₃O₄There is a water-soluble suspension (JP-A-7-126684) obtained by mixing particle powder, an acrylic acid-based water-soluble polymer and a surfactant in water.
[0008]
However, the α-FeOOH particles dispersed in the high-concentration aqueous suspension described in the above-mentioned Japanese Patent Application Laid-Open No. 7-90292 have a needle-like shape, so that the interaction between the particles is large and uniform dispersion is difficult. , The viscosity tends to be high. Fe dispersed in the lubricant described in Japanese Patent No. 2556142₃O₄Since the particles are magnetic, they tend to aggregate and have poor uniform dispersibility and dispersion stability. Further, Fe dispersed in the aqueous suspension described in JP-A-7-126684 mentioned above.₂O₃Since the particles have undergone a process such as heat dehydration, they may be sintered particles or the like, and there are problems such as poor uniform dispersibility.
[0009]
An aqueous suspension of iron oxide particles or hydrous iron oxide particles is strongly required to be excellent in uniform dispersibility and dispersion stability.
[0010]
By the way, among the above-described uses of the aqueous suspension of iron oxide particles or hydrous iron oxide particles, water-based paints, water-based printing inks, water-based cement colorants, water-based cosmetics and the like are used as coloring materials, and as coloring materials, Recently, there is an orange pigment as one of the required hues. Here, orange means “L^*a^*b^*In “Color system” a^*The value is 15-50, and b^*This indicates a hue having a value of 20 to 55.
[0011]
Conventionally, as an orange pigment, organic pigments such as Sudan I, Permanent Orange and Resol Fast Orange, and red lead yellow lead (PbCrO)₄・ PbO) or chrome vermilion (PbCrO)₄・ PbMoO₄・ PbSO₄Inorganic pigments such as) are put into practical use and widely used. However, as described above, organic pigments are expensive, while inorganic pigments contain harmful heavy metals such as lead and chromium and are not preferred. .
[0012]
Currently, iron oxide particles and hydrous iron oxide particles used as orange pigments are yellow goethite (α-FeOOH) particles and red hematite (α-Fe).₂O₃) Mixed powder with particle powder or orange lepidochrosite (γ-FeOOH) particle powder. However, yellow goethite (α-FeOOH) particle powder and red hematite (α-FeO₂O₃) The mixed powder with the particle powder is mixed with different types of particle powder, so the dispersibility in the aqueous medium is not sufficient, and when this is used as an aqueous paint, color separation tends to occur. There is a drawback.
Accordingly, the aqueous suspension having an orange hue is preferably an aqueous suspension using a single composition of lipidoclosite particle powder as an orange pigment.
[0013]
Repidocrocite particles used in aqueous suspensions of lipidocrocite particles not only have good dispersibility in aqueous media, but also strongly require improved coloring and hiding power of the lipidocrocite particles. Has been.
[0014]
As a method for producing the lipid docrosite particle powder, (1) a suspension of pH 7.0 to 9.0 containing ferrous hydroxide obtained by reacting a ferrous salt solution and an alkaline solution, A method for producing lipidocrocite particles by ventilating an oxygen-containing gas at a temperature of ℃ or lower (JP-B-33-6734, etc.), and (2) obtained by reacting a ferrous sulfate aqueous solution and an alkaline aqueous solution. A method for producing lipidocrocite particles by passing an oxygen-containing gas through a suspension containing ferrous hydroxide and having a pH of 5.5 to 7.0 at a temperature of 5 to 15 ° C. 3323 publication, etc.), (3) suspension of ferrous hydroxide obtained by reacting ferrous sulfate aqueous solution and sodium hydroxide aqueous solution with a pH of less than 5.5 in the presence of disodium hydrogen phosphate. At a temperature of about 45 ° C A method for producing lipidocrocite particles by aeration of an elemental gas (Japanese Patent Laid-Open No. 62-108738, etc.), and (4) hydroxylation obtained by reacting a ferrous sulfate aqueous solution and an alkali hydroxide aqueous solution. A suspension containing ferrous iron and having a pH of about 10 or more is bubbled with an oxygen-containing gas in the presence of a water-soluble phosphorus compound or arsenic compound to form a seed crystal of lepidocrotite, and then a temperature of 55 to 100 ° C. A method of producing repidocrocite particles by growing a seed crystal of the repidocrocite within a range (Japanese Patent Publication No. 43-2214) is known.
[0015]
[Problems to be solved by the invention]
An aqueous suspension having excellent dispersibility in an aqueous medium and excellent dispersibility and dispersion stability using inexpensive and non-toxic lepidochrosite particle powder having excellent coloring power and hiding power It is the most demanded to obtain industrially and economically at present, but an aqueous suspension in which the lipid dodecysite particle powder by the production methods (1) to (4) is dispersed in an aqueous medium. Is not enough to meet these requirements.
[0016]
In addition, the lepidochrosite particle powder produced by each of the production methods (1) to (4) is easily formed by forming aggregates of acicular or granular particles resulting from the formation reaction. Dispersibility in the medium is not sufficient, and coloring power and hiding power are not sufficient due to the particle shape.
[0017]
This fact will be described below.
[0018]
In general, the lipid crocite particle powder includes a case where a ferrous chloride aqueous solution is used as an iron raw material and a case where a ferrous sulfate aqueous solution is used. When ferrous chloride aqueous solution is used as the iron raw material, the reaction vessel or the like is corroded, which is not industrial.
[0019]
When ferrous sulfate aqueous solution is used as the iron raw material, the reaction vessel or the like is not corroded. However, the shape of the generated lipid docrosite particles is not affected by any of the production methods (1) to (3). Are acicular particles. And other particles other than the lipidocrocite particles are likely to be mixed due to the generation reaction.
[0020]
That is, when the reaction product pH is in the acidic region, needle-like goethite particles are mixed in addition to the lipidocrocite particles, and when the reaction product pH is in the alkaline region, granular magnetite particles are mixed in addition to the lipidocrocite particles.
[0021]
Further, when the pH region of the generated reaction solution is as low as less than pH 7, alkali metal, SO, which is generated at the same time when the lipidocrosite particles are generated,₄A precipitate containing a fraction, ie RFe₃(SO₄)₂(OH)₆(R = K⁺, Na⁺, NH⁺) Is inevitably contained in the interior of the particles and between the particles. This hardly soluble sulfur-containing iron salt is difficult to remove by washing with water, and the particles are cross-linked. Since it remains in a state, aggregated particles are likely to be generated.
[0022]
Moreover, when the production reaction of a lipid docrosite particle | grain is 15 degrees C or less, the necessity of cooling etc. arises and it is not industrial and economical.
[0023]
In the case of the production method described in (4) above, the presence of a water-soluble phosphorus compound or arsenic compound at the time of nucleation crystal formation allows reaction at a high temperature of 55 to 100 ° C. during the nucleation crystal growth. The particle shape is transformed from a plate-like body, a needle-like body or the like to a cube, a spherical body, or the like, thereby obtaining granular lipidocrocite particles.
In the case of this method, since the shape of the obtained lipidocrosite particles is granular, the coloring power and the hiding power are poor.
[0024]
In addition, in the reaction for producing nucleated particles, as shown in a comparative example described later, the shape of the lipidocrocite particles is needle-like, and granular magnetite particles are mixed in addition to the needle-like lipidocrocite particles.
[0025]
In addition, when the lipidocrocite particle powder produced by each of the production methods (1) to (4) is dispersed in an aqueous medium due to its particle shape, the resulting aqueous suspension has uniform dispersibility. The dispersion stability is not sufficient.
[0026]
Accordingly, the present invention provides a lipidocrosite that is excellent in uniform dispersibility and dispersion stability obtained by dispersing a lipidocrosite particle powder excellent in coloring power, hiding power, and dispersibility in an aqueous medium in an aqueous medium. It is a technical problem to obtain an aqueous suspension of particles.
[0027]
[Means for solving the problems]
The technical problem can be achieved by the present invention as follows.
[0028]
That is, the present invention has a kamaboko plate shape (cuboid shape) having a minor axis diameter of 0.045 to 0.5 μm, a major axis diameter of 0.05 to 1.0 μm, and a thickness of 0.001 to 0.3 μm. ) Having a geometrical standard deviation value of the major axis diameter of 1.70 or less and, if necessary, 1.40 or less, dispersed in an aqueous medium. It is an aqueous suspension of docrosite particle powder.
[0029]
Further, the present invention is the aqueous suspension of any one of the above-mentioned lipidoclosite particles, wherein the lipidoclosite particles dispersed in the aqueous suspension contain 0.5 to 10% by weight of phosphorus. .
[0030]
Further, the present invention may be a kind selected from Al oxide, Al hydroxide, Si oxide and Si hydroxide on the surface of the lipidocrosite particles dispersed in the aqueous suspension. An aqueous suspension of any one of the above-mentioned lipidoclosite particles having a coating layer composed of two or more kinds.
[0031]
The present invention also provides any one of the above-mentioned aqueous suspensions of lipidoclosite particles in which a surfactant is attached to the surface of the particles of the lipidoclosite particles dispersed in the aqueous suspension.
[0032]
The configuration of the present invention will be described in more detail as follows.
[0033]
First, the lipidocrosite particle powder used in the present invention will be described.
[0034]
Each of the lipidocrocite particles constituting the lipidocrocite particle powder used in the present invention has a kamaboko plate shape (cuboid shape). Here, the kamaboko plate shape (cuboid shape) is not only a rectangular parallelepiped that is a hexahedron each side of which is a rectangle, but even if the edges and sides of the rectangular parallelepiped are not necessarily sharp and clear, there are some irregularities, It may be a slightly rounded particle, and refers to a particle having a major axis to minor axis ratio of about 1.1: 1 to 5: 1 and a thickness of 0.001 to 0.3 μm. When the shape of the particles is not a kamaboko plate shape (cuboid shape), excellent coloring power and hiding power cannot be obtained, and uniform dispersion and dispersion stability are not sufficient when an aqueous suspension is used. In consideration of coloring power and hiding power, the ratio of the major axis diameter to the minor axis diameter is preferably about 1.2: 1 to 4.8: 1.
[0035]
The minor axis diameter is 0.045 to 0.5 μm. In the case of less than 0.045 μm, the dispersibility is impaired due to an increase in intermolecular force due to finer particles. Further, the particles become needle-like, and excellent coloring power and hiding power cannot be obtained. If it exceeds 0.5 μm, the dispersibility is good, but due to the coarsening of the particles, when using this as a water-based paint, a smooth coated surface cannot be obtained. The preferred minor axis diameter is 0.045 to 0.3 μm, more preferably 0.045 to 0.2 μm.
[0036]
The major axis diameter is 0.05 to 1.0 μm. If it is less than 0.05 μm, the dispersibility is impaired due to an increase in intermolecular force due to the refinement of the particles. When the thickness exceeds 1.0 μm, the particles become needle-like and excellent coloring power and hiding power cannot be obtained. Also, due to the coarsening of the particles, a smooth coated surface cannot be obtained when this is used as a water-based paint. The major axis diameter is preferably 0.05 to 0.7 μm, more preferably 0.05 to 0.5 μm.
[0037]
The thickness is 0.001 to 0.3 μm. In the case of less than 0.001 μm, the dispersibility is impaired due to an increase in intermolecular force due to finer particles. Moreover, since the thickness is reduced, excellent coloring power and hiding power cannot be obtained. When the thickness exceeds 0.30 μm, the surface becomes smooth when a water-based paint is formed using this due to the coarsening of the particles. The preferred thickness is 0.001 to 0.2 μm, more preferably 0.001 to 0.1 μm.
[0038]
SO of the lipid crocite particles used in the present invention₄The content is 1000 ppm or less, preferably 500 ppm or less, more preferably 200 ppm or less. No cross-linking is observed between the particles, and the individual particles are scattered. SO of the obtained lipidocrosite particle powder₄The lower limit of the content is about 0.01 ppm.
[0039]
The lepidochrosite particle powder obtained in the absence of nuclei has a geometric standard deviation value of the major axis diameter of 1.70 or less. The geometric standard deviation value serves as an index representing the degree of particle size distribution of particles, and the smaller the value, the better the particle size distribution of particles. When it exceeds 1.70, coloring power and hiding power become insufficient. Considering coloring power and hiding power, it is preferably 1.60 or less. The lower limit of the obtained lipidocrosite particle powder is about 1.05.
[0040]
The lepidochrosite particle powder obtained in the presence of nuclei has a geometric standard deviation value of the major axis diameter of 1.40 or less. When it exceeds 1.40, it cannot be said that the particle size distribution is further improved. Considering coloring power and hiding power, it is preferably 1.38 or less, more preferably 1.35 or less. The lower limit of the obtained lipidocrosite particle powder is about 1.01.
[0041]
A repi consisting of lipidocrocite particles having a rectangular parallelepiped shape having a minor axis diameter of 0.045 to 0.5 μm, a major axis diameter of 0.05 to 1.0 μm, and a thickness of 0.001 to 0.3 μm. The color of the docrosite particle powder is a^*The value is 15.0-50.0, and b^*The value is 20.0-55.0, L^*The value is 20.0-70.0.
[0042]
a^*When the value exceeds 50.0, redness becomes strong, which is not preferable. When it is less than 15.0, redness is insufficient, which is not preferable.
[0043]
b^*When the value exceeds 55.0, yellowishness becomes strong, which is not preferable. If it is less than 20.0, the yellowness necessary for the orange color development is insufficient, which is not preferable.
[0044]
L^*If the value exceeds 70.0, the color of the pigment becomes too bright, which is not preferable. If it is less than 20.0, it becomes dark and dull, which is not preferable.
[0045]
The difference in geometric standard deviation value is^*Value or b^*Although it does not affect the hue such as the value, as is well known, there is a slight difference in the dust, and as the geometric standard deviation value becomes smaller, the dust tends to become smaller.
[0046]
Each of the lipidocrocite particles constituting the lipidocrocite particle powder used in the present invention preferably contains 0.05 to 10% by weight of phosphorus, more preferably 0.1 to 5% by weight. When the amount is less than 0.05% by weight, the electrical repulsion between the lipidocrosite particles in the aqueous suspension becomes small, and the dispersion stability may be impaired. If it exceeds 10% by weight, the effect is saturated and it is meaningless to contain more than necessary.
[0047]
Each of the lipidocrocite particles constituting the lipidocrocite particle powder used in the present invention is a kind selected from Al oxide, Al hydroxide, Si oxide and Si hydroxide on the particle surface or It is preferable to have a coating layer composed of two or more kinds.
In this case, the abundance on the particle surface is preferably 0.01 to 50% by weight, more preferably 0.05 to 20% by weight of Al in terms of Al. Si is SiO.₂Preferably in terms of conversion, it is 0.01 to 50% by weight, and more preferably 0.05 to 20% by weight.
[0048]
It is preferable that a surfactant is attached to the surface of each of the lipidocrocite particles constituting the lipidocrocite particle powder used in the present invention.
In this case, the adhesion amount on the particle surface is preferably 0.01 to 10% by weight, more preferably 0.05 to 5% by weight in terms of carbon.
[0049]
Next, a method for producing the lipidocrosite particle powder used in the present invention will be described.
[0050]
The lipid crocite particle powder used in the present invention comprises a ferrous sulfate aqueous solution, an alkali hydroxide aqueous solution, and 0.1 to 5.0 mol% of a phosphorus compound or citric acid compound or the both compounds at a temperature of 25 to 55. Mixing in the temperature range of 0 ° C. produces a suspension with a pH value of 7-9 containing iron hydroxide, which is then subjected to a pH value, optionally in the presence of nuclei particles. Can be obtained by oxidizing the iron hydroxide by aeration of an oxygen-containing gas in a temperature range of 25 to 55 ° C. while adjusting the range of 7 to 9.
[0051]
As the aqueous alkali hydroxide solution, an aqueous sodium hydroxide solution, an aqueous potassium hydroxide solution, or the like can be used.
[0052]
Examples of the phosphorous compounds include phosphates such as orthophosphoric acid, metaphosphoric acid, pyrophosphoric acid, triphosphoric acid and tetraphosphoric acid, sodium salts such as disodium hydrogen phosphate, sodium dihydrogen phosphate and trisodium phosphate, phosphorus Ammonium salts such as ammonium dihydrogen phosphate, diammonium hydrogen phosphate, and sodium ammonium hydrogen phosphate, potassium salts such as tripotassium phosphate, potassium dihydrogen phosphate, and dipotassium hydrogen phosphate can be used.
[0053]
Examples of the citric acid compound include citric acid, ammonium salts such as ammonium citrate and ammonium hydrogen citrate, potassium salts such as potassium citrate and potassium hydrogen citrate, sodium salts such as sodium citrate and sodium hydrogen citrate. In addition, lithium salts such as lithium citrate can be used.
[0054]
The order of addition of the ferrous sulfate aqueous solution, the alkali hydroxide aqueous solution, the phosphorus compound, the citric acid compound, or the both compounds may be the first or the same, and in any case, A docrosite particle powder is obtained.
[0055]
In consideration of generating only the lipidocrosite particle powder without generating other particles other than the lipidocrocite particles, a ferrous sulfate aqueous solution, an alkali hydroxide aqueous solution, a phosphorus compound, a citric acid compound, or both of these compounds Are preferably mixed as uniformly as possible, and it is preferable to add a phosphorus compound, a citric acid compound, or both of these compounds and a ferrous sulfate aqueous solution in advance, and then add the mixed solution to an aqueous alkali hydroxide solution. More preferably, the mixed solution may be added to the aqueous alkali hydroxide solution after aging in advance.
[0056]
The aging time of the mixed solution is preferably 10 minutes or more, more preferably 30 minutes or more. The upper limit of the aging time is not particularly limited, but is about 120 minutes industrially.
[0057]
Further, the above mixed solution added to the aqueous alkali hydroxide solution may be added at one time. However, in consideration of the uniform mixing of the aqueous solution, a small amount may be added continuously or intermittently over 10 to 120 minutes. In particular, it is more preferable to add over 50 to 70 minutes.
[0058]
The mixing ratio of the ferrous sulfate aqueous solution and the alkali hydroxide aqueous solution is such that the pH value of the suspension containing the iron hydroxide produced by reacting the ferrous sulfate aqueous solution and the alkali hydroxide aqueous solution is 7-9. Any ratio within the range may be used. When the pH value of the suspension is less than 7, acicular goethite particles are mixed in addition to the lipidocrocite particles. When the pH value of the suspension exceeds 9, granular magnetite particles are mixed in addition to the lipidocrocite particles.
[0059]
The mixing ratio of the phosphorus compound, the citric acid compound or the both compounds is 0.1 to 5 mol% with respect to Fe. If it is less than 0.1 mol%, it becomes difficult to produce only the lipid docrosite particles, and granular magnetite particles are mixed. When the amount exceeds 5 mol%, lepidochrosite particles can be obtained, but since the effect of addition is saturated, there is no point in adding more than necessary.
[0060]
The addition of the phosphorus compound or the citric acid compound or both of these compounds must be before aeration of the oxygen-containing gas to the suspension, including ferrous sulfate aqueous solution, alkali hydroxide aqueous solution, iron-containing precipitate It can be added to any of the suspensions.
[0061]
In order to produce only the lipidocrocite particle powder without producing other particles other than the lipidocrocite particles, it is preferably added to the aqueous ferrous sulfate solution as described above.
[0062]
The temperature at the time of mixing raw materials is 25 to 55 ° C. When the temperature is lower than 25 ° C., it takes a long time for the reaction of forming the lipid docrosite, which is not industrial and economical. When the temperature exceeds 55 ° C., granular magnetite particles other than the lipidocrocite particles are mixed.
[0063]
It is important to adjust the pH value when mixing the raw materials to be in the range of 7-9. When the pH value is out of the range, it is difficult to produce only the lipidocrosite particle powder. On the other hand, when the pH value is less than 7, a large amount of sulfur-containing iron salt is contained in the lipidoclosite particle powder.
[0064]
Oxidation of the suspension containing iron hydroxide is carried out by passing an oxygen-containing gas (for example, air) through the liquid. The aeration rate is preferably 0.5 to 100 l per minute with respect to 10 l of the reaction mother liquor.
[0065]
The oxidation reaction temperature is 25 to 55 ° C. When the temperature is lower than 25 ° C., the oxidation reaction takes a long time, which is not industrial and economical. When it exceeds 55 ° C., it becomes difficult to produce only the lipidocrocite particles, and granular magnetite particles and the like are mixed in addition to the lipidocrocite particles.
[0066]
In the oxidation reaction, the pH value gradually decreases with the progress of the oxidation reaction, so it is important to adjust the pH value to a range of 7 to 9 by adding an alkaline aqueous solution such as sodium hydroxide. When the pH value is less than 7, it is difficult to produce only the lipid dodecite site, and acicular goethite particles are mixed. When the pH value exceeds 9, it becomes difficult to produce only the lipid docrosite particles, and granular magnetite particles are mixed.
[0067]
The oxidation reaction time from the start of the oxidation reaction to the end of the reaction is 24 hours or less, particularly 12 hours or less. Therefore, the yield of the lipidocrosite particle powder per unit time (unit volume / yield per unit time) is 4.3 to 15.6 kg / m.³-It is large with hr, which is industrially and economically advantageous.
[0068]
In addition, since the production | generation reaction of a repidocrocite particle | grain is complete | finished and an oxidation reaction will no longer advance, since a pH value will no longer change, pH value will become constant and it will no longer be necessary to add the NaOH solution for pH adjustment. Time is the end point of the oxidation reaction.
[0069]
In the production reaction of the lipidocrosite particle powder as described above, if necessary, nuclei crystal particles may be present. In this case, the geometric standard deviation of the major axis diameter is 1.40 or less, in other words, It is possible to produce a lipidoclosite particle powder having a better particle size distribution.
[0070]
If necessary, the core crystal particles to be added are ferrous hydroxide colloid, ferric hydroxide colloid obtained by a known production method, iron hydroxide such as green last, iron such as hematite, magnetite, and maghemite. Any of oxides and iron-containing hydrous oxides such as goethite, lepidochrosite, and akaganite, and these nucleation particles are the same reaction tower as the reaction tower for producing the lipidocrosite particle powder according to the present invention. May be used, or may be produced using another reaction tower. In consideration of the particle size distribution of the major axis diameter of the target lepidochrosite particle powder, particles having few aggregated particles and individual ones are preferable.
Preferably, it is a lipidocrosite nucleus crystal particle.
[0071]
A preferred method for producing the lipid docrosite nucleus crystal particles is that a ferrous sulfate aqueous solution, an alkali hydroxide aqueous solution, and 0.1 to 5.0 mol% of a phosphorus compound or citric acid compound or the both compounds are added at a temperature of 25 to 25%. A method of obtaining lipid hydroxide nuclei particles by mixing iron in the range of 55 ° C. and pH 7-9 to obtain iron hydroxide, and then blowing air further into the suspension containing the iron hydroxide. Etc.
[0072]
The abundance of the nucleus crystal particles is preferably 0.001 to 0.5 mol / l in terms of Fe. When the amount is less than 0.001 mol / l, the number of nucleation particles is too small, so that the growth of the particles becomes non-uniform and it becomes difficult to generate the lipid dodecite particles having an excellent particle size distribution. If it exceeds 0.5 mol / l, the number of nucleation particles increases, and the particle growth becomes insufficient.
[0073]
In order to further improve the dispersibility in the aqueous medium, each of the lipidocrocite particles constituting the lipidocrosite particle powder used in the present invention has a surface of Al oxide, Al hydroxide, Si oxidation in advance. It is preferable to form a coating layer made of one kind or two or more kinds selected from a product or a hydroxide of Si.
[0074]
The coating layer is formed by dispersing the lipidocrocite particle powder in water, adding an aluminum compound and / or a silicon compound, and adjusting the pH, thereby forming particles of the particle constituting the lipidocrocite particle powder. A coating layer composed of one or more selected from Al hydroxide, Si oxide, or Si hydroxide can be formed on the surface.
[0075]
The addition of the aluminum compound and / or the silicon compound can be carried out by dropping at once, or divided into several times or continuously. It is preferable to adjust the pH before and after each addition of the aluminum compound and / or silicon compound. The pH range to be adjusted is 5.0 to 9.0, preferably 6.0 to 8.0.
[0076]
As the aluminum compound, aluminum salts such as aluminum sulfate, aluminum chloride, aluminum nitrate, aluminum acetate and aluminum oxalate, alkali aluminates such as sodium aluminate and potassium aluminate, and alumina sol can be used.
The amount of the aluminum compound added is preferably 0.01 to 50% by weight and more preferably 0.05 to 20% by weight in terms of Al with respect to the lepidochrosite particle powder. When the amount is less than 0.01% by weight, the dispersion in the aqueous medium is insufficient. When the amount exceeds 50% by weight, the coating effect is saturated, and there is no meaning to add more than necessary.
[0077]
As the silicon compound, water glass, sodium silicate, potassium silicate, calcium silicate, colloidal silica, silicon dioxide or the like can be used. The addition amount of the silicon compound is SiO2 with respect to the lepidochrosite particle powder.₂Preferably in terms of conversion, it is 0.01 to 50% by weight, and more preferably 0.05 to 20% by weight. When the amount is less than 0.01% by weight, the dispersion in the aqueous medium is insufficient. When the amount exceeds 50% by weight, the coating effect is saturated, and there is no meaning to add more than necessary.
[0078]
When using an aluminum compound and a silicon compound together, the amount in terms of Al and SiO₂The total amount with the converted amount is preferably 0.01 to 50% by weight. When the amount is less than 0.01% by weight, the dispersion in the aqueous medium is insufficient. When the amount exceeds 50% by weight, the coating effect is saturated, and there is no meaning to add more than necessary.
[0079]
In order to further improve the dispersibility in the aqueous medium, it is preferable that the surface of each of the lipidocrocite particles constituting the lipidoclosite particle powder used in the present invention is previously coated with a surfactant.
[0080]
Formation of the coating layer with the surfactant on the particle surface of the lipid docrosite particle can be performed by a dry method or a wet method.
In the case of the dry method, the lepidochrosite particle powder and the surfactant can be kneaded with a wheel-type kneader, a cracker, a Henschel mixer or the like.
In the case of the wet method, it is possible to disperse the lipidocrocite particles in water and add a surfactant or disperse the lipidocrocite particle powder in water in which the surfactant is dissolved. it can.
[0081]
The surfactant is an anionic surfactant or a nonionic surfactant.
Examples of the anionic surfactant include alkyl sulfate ester, alkylbenzene sulfonate, naphthalene sulfonate formalin condensate, aromatic sulfonate formalin condensate, and carboxylic acid type polymer surfactant.
Examples of nonionic surfactants include polyoxyethylene alkyl ether and polyoxyethylene alkylphenyl ether.
[0082]
The addition amount of the surfactant is preferably 0.01 to 10% by weight, more preferably 0.05 to 5% by weight, in terms of carbon, with respect to the lepidochrosite particle powder. When the amount is less than 0.01% by weight, the dispersion in the aqueous medium is insufficient. When the amount exceeds 10% by weight, the coating effect is saturated, so there is no point in adding more than necessary.
[0083]
The size of the lipidocrocite particles whose particle surface is coated with the coating is substantially the same as the size of the lipidocrosite particles before treatment, and the minor axis diameter is 0.045 to 0.5 μm, The major axis diameter is 0.05 to 1.0 [mu] m, the thickness is 0.001 to 0.3 [mu] m, and it has a kamaboko plate shape (cuboid shape) substantially the same as that before the coating treatment.
[0084]
Next, the aqueous suspension of lipidocrosite particles according to the present invention will be described.
[0085]
The aqueous suspension of lipidoclosite particles according to the present invention is obtained by dispersing the specific lipidoclosite particle powder in an aqueous medium.
[0086]
The concentration of the lipidoclosite particle powder in the aqueous suspension of the lipidoclosite particles according to the present invention is 0.01 to 60% by weight, preferably 0.1 to 50% by weight.
[0087]
Regarding the dispersibility of the aqueous suspension of the lipidoclosite particles according to the present invention, the uniform dispersibility (d) is 1 to 2, preferably 1 to 1.8, further according to the evaluation method of the embodiment described later. Preferably it is 1-1.6. The dispersion stability (V) is 0.8 to 1.0, preferably 0.85 to 1.0, and more preferably 0.88 to 1.0 according to the evaluation method of the embodiment described later.
[0088]
The viscosity of the aqueous suspension of lipidoclosite particles according to the present invention is 1 to 25600 cP, preferably 1 to 5000 cP.
[0089]
The pH of the aqueous suspension of lipidoclosite particles according to the present invention is 3 to 11, preferably 4 to 10.
[0090]
The aqueous suspension of the lipidoclosite particles according to the present invention is mainly composed of water as a solvent, and other additives include a surfactant, a water-soluble resin, a dispersant, a charge control agent, and leveling. An agent and a water-based paint solvent may be contained.
[0091]
As the surfactant, those used for the surface treatment of the lipidoclosite particles can be used.
[0092]
Examples of the water-soluble resin include commonly used water-soluble alkyd resins, water-soluble acrylic resins, water-soluble urethane resins, water-soluble epoxy resins, water-soluble melamine resins, acrylic emulsion resins, acrylic / styrene emulsion resins, urethane emulsion resins, An epoxy emulsion resin, a vinyl acetate emulsion resin, or the like can be used.
[0093]
As the water-based paint solvent, commonly used butyl cellosolve, butyl alcohol, and the like can be used.
[0094]
In addition, the aqueous suspension of the lipidoclosite particles according to the present invention can be used as a stock solution or diluted depending on the application. The concentration of the lipidoclosite particles is, for example, 1 for water-based paints. 0.0 to 30% by weight, 5.0 to 20% by weight for the water-based cement colorant, and 0.5 to 20% by weight for the water-based lubricant for rolling the steel sheet are preferable.
[0095]
Further, when an aqueous paint is prepared using an aqueous suspension of the lipidoclosite particles according to the present invention, the coloring power is 4 to 5, the hiding power is 29 or less, preferably 27 or less, and the preferred lower limit is 15 It is. The glossiness on the coating surface of the coated piece is 71 or more, preferably 75 or more, and a preferred upper limit is 130.
[0096]
Next, a method for producing an aqueous suspension of lipidocrosite particles according to the present invention will be described.
[0097]
The aqueous suspension of lipidocrosite particles according to the present invention can be obtained by dispersing the specific lipidocrosite particle powder in an aqueous medium using a disperser.
[0098]
The aqueous medium in the present invention may be anything that mainly contains water.
[0099]
Examples of the disperser used to disperse the lipidocrosite particle powder in the present invention in an aqueous medium include a known homomixer, horizontal SGM, homomic line mill, and sand grinder.
[0100]
[Embodiments of the Invention]
A typical embodiment of the present invention is as follows.
[0101]
The major axis diameter and minor axis diameter of the particles are about 350 particles shown in the photograph (× 120,000) obtained by enlarging the electron micrograph (× 30000) four times in the longitudinal direction and the transverse direction, respectively. The shaft diameter was measured, and the average value was shown.
[0102]
Regarding the thickness of the particles, among the particles shown in the photograph prepared in the same manner as described above, only the particles in an inverted state were extracted, the thicknesses of about 100 particles were measured, and the average value was shown.
[0103]
The geometric standard deviation (σg) of the major axis diameter of the particle was indicated by a value obtained by the following method. That is, the value measured for the major axis diameter of the particles shown in the above enlarged photograph is calculated on the basis of the actual major axis diameter and the number of particles calculated from the measured value, and the horizontal axis on the lognormal probability paper according to a statistical method. The major axis diameter of the particles is plotted on the vertical axis, and the cumulative number of particles belonging to each of the predetermined major axis diameter sections (under the integrated sieve) is plotted in percentage on the vertical axis. Then, the value of the major axis diameter corresponding to 50% and 84.13% of the number of particles is read from this graph, and the geometrical standard deviation value (σg) = major axis diameter / accumulated at 84.13% under the cumulative sieve. The value was calculated according to the major axis diameter (geometric mean diameter) at 50% under the sieve. The smaller the geometric standard deviation value, the better the particle size distribution of the major axis diameter of the particles.
[0104]
Particle SO₄For the content, 5 g of a sample was weighed into a 300 ml Erlenmeyer flask, 100 ml of pure water was added, and the mixture was heated for about 5 minutes to be boiled to dissolve the hardly soluble sulfur-containing iron salt present on the particle surface. The obtained supernatant was designated as No.1. Filter using 5C filter paper and add SO in the filtrate.₄ ^2-Was measured using an induction plasma emission spectroscopic analyzer (Seiko Electronics Co., Ltd.).
[0105]
Each content of P, Al, and Si in the particles was measured using a “fluorescence X-ray analyzer 3063M type” (manufactured by Rigaku Denki Kogyo Co., Ltd.) in accordance with “General X-ray fluorescence analysis rules” of JIS K0119. .
[0106]
The amount of the surfactant attached to the particles was indicated by a value obtained by measuring the amount of carbon using “Horiba Metal Carbon / Sulfur Analyzer EMIA-2200” (manufactured by Horiba, Ltd.).
[0107]
The hue of the powder is 0.5g of lipidocrocite particle powder and 0.7cc of castor oil, kneaded with a Hoover-type Mahler to make a paste, and 4.5g of clear lacquer is added to this paste, kneaded and made into a paint, cast coat An application piece (coating thickness: about 30 μm) coated on a paper using a 6 mil applicator was prepared, and a multi-light source spectrocolorimeter MSC-1S-2D (manufactured by Suga Test Instruments Co., Ltd.) was used for the coating piece. Used, color index L according to JIS Z 8729^*Value, a^*Value and b^*The values are shown as measured values.
[0108]
a^*The value represents redness, and the larger the value, the stronger the redness. b^*The value represents yellowishness, and the larger the value, the stronger the yellowishness. Therefore, orange is a^*Value and b^*It can be expressed by value. L^*The value indicates the brightness.
[0109]
The uniform dispersibility (d) of the aqueous suspension is determined by determining the average major axis diameter obtained from the above-mentioned electron micrograph as d.₁The particle diameter obtained using a laser diffraction particle size distribution analyzer HELOS LA / KA (JEOL Ltd.)₂D = d₂/ D₁It was evaluated with. In this case, d = 1 when each particle is completely separated, and a value of d larger than 1 indicates that the particles are in an agglomerated state and the uniform dispersibility is poor. is there.
[0110]
The dispersion stability (V) of the aqueous suspension is determined by the constant volume (V₀) After 24 hours of standing at 25 ° C., when particles settled, the volume of the particle suspension excluding the sedimented volume is V₁V = V when₁/ V₀It was evaluated with. When the particles did not settle, V = 1.0. As the value of V is smaller than 1.0, the particles are settled, indicating that the dispersion stability is poor.
[0111]
The pH value of the aqueous suspension was measured according to JIS Z 8802-7, and the obtained value was defined as the pH value of the aqueous suspension.
[0112]
The dispersibility in the water-based paint produced using the aqueous suspension was examined by the magnitude of the glossiness of the coated surface of the coated piece produced in the same manner as in the embodiment of the present invention.
[0113]
The glossiness was determined by measuring the 60 ° gloss of the coated surface using a gloss meter UGV-5D (manufactured by Shimadzu Corporation). The larger the gloss value, the better the dispersibility.
[0114]
The hiding power of the water-based paint was determined by the cryptometer method described in the section “8.2 hiding power” of JIS K 5101-1991 “Pigment Test Method”. The hiding power is indicated by a scale value when the boundary line is hidden and cannot be seen, and the larger the scale value is, the smaller the hiding power is.
[0115]
The tinting strength of the water-based paint is the standard white paint (TiO 2) prepared under the same conditions as the obtained paint and the embodiment of the invention described later.₂: Coloring paint obtained by mixing 1:10 with a standard paint using TCR73 Co., Ltd. manufactured by Tochem Products Co., Ltd., was visually inspected for the degree of coloring, and was evaluated in five stages (1: almost no coloring) 2: colored to a clear level, 3: apparently colored, 4: fairly colored, 5: markedly colored). 5 indicates the highest coloring power.
[0116]
<Production of Repidocrocite Particle Powder>
First, the following solution A was prepared and placed in a 35 ° C. chamber.
[0117]
Solution A: To a disodium hydrogen phosphate solution prepared by dissolving 8.66 g of disodium hydrogen phosphate in 300 ml of water, 1663 ml of a 1.834 mol / l aqueous ferrous sulfate solution was added and mixed, and water was further added. Mixed solution with a capacity of 2700 ml.
[0118]
Next, the production reaction of the lipid docrosite particle | grains was performed.
[0119]
After heating 2000 ml of water charged in a bubble column (reactor) having an effective volume of 5 l to 40 ° C., the air was aerated and stirred at a rate of 15 l / min, and then a 0.1 N NaOH solution was added. The pH value was adjusted to 8. Immediately after the pH value was adjusted, the solution A that had been aged for 30 minutes in advance at 35 ° C. was started to be introduced into the bubble column at a rate of 45 ml / min, and the addition was continued for 60 minutes. During the introduction of the solution A, the temperature in the bubble column was controlled at 40 ° C., and a 4.5N NaOH aqueous solution was intermittently added from the NaOH tank to constantly adjust the pH value of the reaction slurry to about 8. Even after the introduction of the solution A was completed, the temperature was maintained at 40 ° C. and the pH value was maintained at 8 ° C. while aerated and stirred. An orange precipitate was obtained 4.5 hours after the start of the reaction.
[0120]
The obtained orange precipitate was filtered and washed with water by a conventional method, and then dried at 80 ° C. for 24 hours to obtain a dried product. Yield 12.04 kg / m³・ It was time. As shown in the X-ray diffraction pattern of FIG. In FIG. 1, peak A is lepidocrotite (γ-FeOOH). As shown in the electron micrograph (× 30000) of FIG. 2, this lipidocrosite particle powder is a particle having a rectangular parallelepiped shape, the minor axis diameter is 0.057 μm, the major axis diameter is 0.12 μm, and the thickness is 0. The major axis diameter: minor axis diameter was 2.1: 1. The geometric standard deviation value of the major axis diameter was σg = 1.38, and the particle size distribution was excellent. Soluble SO₄Was 52 ppm.
[0121]
<Production of aqueous suspension of lipidocrosite particles>
After 350 g of the above-mentioned lipidocrosite particle powder was coarsely pulverized in advance with a Nara type pulverizer, it was put into 3.5 l of pure water and peptized for 60 minutes using a homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.).
[0122]
Next, the obtained slurry of lipidocrocite particles was mixed and dispersed for 3 hours at a shaft rotational speed of 2000 rpm while circulating through the horizontal SGM (Dispamat SL: manufactured by ESC Adchem). The aqueous suspension of the obtained lipidocrosite particles had a particle concentration of 10% by weight, a uniform dispersibility of 1.33, a dispersion stability of 0.92, a viscosity of 207 cP, and a pH value of 7.1.
[0123]
<Manufacture of water-based paint>
In a 140 ml glass container, 30 g of the aqueous suspension of the above-mentioned rapid crocite particles (concentration of 10% by weight of the lipid crocite particles) and a water-soluble alkyd resin, an antifoaming agent and butyl cellosolve are blended in the following composition ratio. Then, it was added together with 90 g of 3 mmφ glass beads, and mixed and dispersed for 90 minutes with a paint shaker to obtain an aqueous paint.
[0124]
100.0 parts by weight of aqueous suspension of rapid crosite particles
Water-soluble alkyd resin 66.8 parts by weight
(S-118 Dainippon Ink & Chemicals, Inc.)
19.6 parts by weight of water-soluble melamine resin
(S-695 Dainippon Ink & Chemicals, Inc.)
Defoamer 0.1 parts by weight
(Nopco 8034 made by San Nopco)
[0125]
The coloring power measured using the obtained paint was 5, and the hiding power was 21.
[0126]
The glossiness of the coated surface produced using this water-based paint was 83%.
[0127]
[Action]
The present inventor already has a kamaboko plate shape (cuboid shape), and since the individual lipidocrocite particles are disjoint due to a small amount of the hardly soluble sulfur-containing iron salt, the dispersibility is excellent. Invented a lipid crocite particle powder, which is an orange pigment having excellent coloring power and hiding power due to its shape, and a method for producing the same, and proposed in Japanese Patent Application No. 8-227545. Kamaboko plate-shaped lepidochrosite particle powder as it is, or if necessary, one or more selected from Al oxide, Al hydroxide, Si oxide and Si hydroxide on the particle surface After forming a coating layer made of the above, further, a coating layer made of a surfactant is formed on the particle surface as necessary, and then dispersed in an aqueous medium, whereby a lipidochroma having excellent uniform dispersibility and dispersion stability. In which it was possible to obtain an aqueous suspension of bets particles.
[0128]
In addition, since the aqueous suspension obtained by dispersing the powder composed of phosphorus-containing lipidocrocite particles in an aqueous medium can increase the electric repulsion between the dispersed particles, Dispersion stability can be improved.
[0129]
【Example】
Next, examples and comparative examples are given.
[0130]
Examples 1-32, Comparative Examples 1-18, Use Examples 1-4, Comparative Use Examples 1-3;
<Production of Repidocrocite Particle Powder>
Examples 1-3, Comparative Examples 1-7
Various types of ferrous salt aqueous solution, concentration and amount, phosphoric acid compound and citric acid compound type and amount, alkaline aqueous solution type and concentration, raw material mixing method, pH value and temperature during mixing and reaction Except for the above, a reaction product was obtained in the same manner as in the above embodiment.
[0131]
As a result of X-ray diffraction, it was confirmed that the particles obtained in Examples 1 to 3, Comparative Example 4 and Comparative Example 6 were all composed of only the lipid docrosite particles.
[0132]
As a result of X-ray diffraction, the reaction products obtained in Comparative Examples 1, 3 and 5 were all magnetite (Fe₃O₄) Was found to be mixed.
[0133]
FIG. 3 shows an X-ray diffraction pattern of the reaction product obtained in Comparative Example 2, and FIG. 4 shows an electron micrograph (× 30000). In FIG. 3, peak A is lepidocrotite, and peak B is goethite (α-FeOOH), and it was recognized that goethite particle powder was mixed in addition to the lipidocrosite particle powder. Moreover, as shown in FIG. 4, the rectangular parallelepiped particle and the acicular particle were mixed.
[0134]
FIG. 5 shows an X-ray diffraction pattern of the reaction product obtained in Comparative Example 7, and FIG. 6 shows an electron micrograph (× 30000). In FIG. 5, peak A is lepidocrotite and peak C is magnetite, and it was recognized that magnetite particle powder was mixed in addition to the lipidocrosite particle powder. Moreover, as shown in FIG. 4, rectangular parallelepiped particles and granular particles were mixed.
[0135]
The main production conditions at this time are shown in Table 1, and various characteristics are shown in Table 2.
[0136]
[Table 1]

[0137]
[Table 2]

[0138]
<Production of Repidocrocite Particle Powder in the Presence of Nucleated Crystals>
Example 4
First, the following B and C solutions were prepared and placed in separate chambers at 35 ° C.
[0139]
Solution B: To a disodium hydrogen phosphate solution obtained by dissolving 5.68 g of disodium hydrogen phosphate in 300 ml of water, 1091 ml of a 1.834 mol / l ferrous sulfate aqueous solution was added and mixed, and water was further added. Mixed solution with a capacity of 1500 ml.
[0140]
Solution C: To disodium hydrogen phosphate in which 2.98 g of disodium hydrogen phosphate was dissolved in 150 ml of water, 572 ml of a 1.834 mol / l ferrous sulfate aqueous solution was added and mixed. 1000 ml mixed solution.
[0141]
Next, a production reaction of the lipidocrocite particles is performed in the presence of the nuclei particles.
[0142]
The above solution C was aged at 35 ° C. for 30 minutes in advance while agitating with aeration of air at a rate of 10 l / min after heating 2000 ml of water charged into a bubble column (reactor) having an effective volume of 5 l to 35 ° C. Was added to the bubble column, followed by stirring with aeration for 5 minutes.
[0143]
Next, a separately prepared 35 ° C. NaOH aqueous solution (91 ml of 18.4 N NaOH aqueous solution was diluted with water to 500 ml to obtain an aqueous solution corresponding to 0.8 equivalent to Fe contained in C solution). It was added little by little to the bubble column, and after completion of addition, air was aerated at a rate of 10 l / min for 5 minutes, followed by stirring to carry out a reaction for producing nucleated particles.
[0144]
Subsequently, the temperature was raised to 40 ° C. while aerated and stirred with air at a rate of 10 l / min, and then the pH value was adjusted to 8 by adding a little 4.5 N NaOH solution. Immediately after the adjustment of the pH value, charging of the B solution at 35 ° C., which was aged at 35 ° C. for 30 minutes, was started in the bubble column at a rate of 25 ml / min and continued to be performed in 60 minutes. During the introduction of the solution B, the temperature in the bubble column was controlled at 40 ° C., and a 4.5N NaOH aqueous solution was intermittently added from the NaOH tank to constantly adjust the pH value of the reaction slurry to about 8. Even after the introduction of the solution B was completed, the temperature was maintained at 40 ° C. and the pH value at 8 while the air was continuously vented. An orange precipitate was obtained 8.3 hours after the start of the reaction.
[0145]
The obtained orange precipitate was filtered and washed with water by a conventional method, and then dried at 80 ° C. for 24 hours to obtain a dried product. Yield 6.53 kg / m³・ It was time. As a result of X-ray diffraction, only the lipidocrocite particle powder was observed in this dried product. As a result of observation by an electron microscope, the lipidocrosite particle powder is a particle having a rectangular parallelepiped shape, the minor axis diameter is 0.045 μm, the major axis diameter is 0.090 μm, the thickness is 0.017 μm, and the major axis is Diameter: The minor axis diameter was 2.0: 1. The geometric standard deviation value of the major axis diameter was σg = 1.32 and the particle size distribution was more excellent. Also,. Soluble SO₄Was 90 ppm.
[0146]
Examples 5-7, Comparative Example 8
Type and amount of nuclei, concentration and amount of ferrous salt aqueous solution, type and amount of phosphoric acid compound and citric acid compound, type and concentration of alkaline aqueous solution, mixing method of raw materials, pH value during mixing and reaction, and A product reaction product was obtained in the same manner as in Example 4 except that the temperature was varied.
[0147]
As a result of X-ray diffraction, it was confirmed that all the particles obtained in Examples 5 to 7 and Comparative Example 8 consisted only of lipidocrosite particle powder.
[0148]
FIG. 7 shows an X-ray diffraction pattern of the reaction product obtained in Example 6, and FIG. 8 shows an electron micrograph (× 30000). In FIG. 7, peak A is lepidocrotite, and it was recognized that it consisted only of lepidochrosite particle powder.
The main production conditions at this time are shown in Table 3, and various characteristics are shown in Table 4.
[0149]
[Table 3]

[0150]
[Table 4]

[0151]
<Surface coating treatment of lipidocrosite particle powder>
Examples 8-16
Under the conditions shown in Tables 5 and 6, the surface of the lipidocrocite particles was subjected to a surface coating treatment with an Al compound, a Si compound and / or a surfactant.
Tables 5 and 6 show the main production conditions and various characteristics at this time.
[0152]
[Table 5]

[0153]
[Table 6]

[0154]
<Production of aqueous suspension of lipidocrosite particles>
Examples 17-32, Comparative Examples 9-18
An aqueous suspension was obtained in the same manner as in the above-described embodiment except that the kind of particle powder, the amount added, and the kind of surfactant were variously changed. The conditions and various characteristics are shown in Tables 7 and 8.
[0155]
[Table 7]

[0156]
[Table 8]

[0157]
<Manufacture of water-based paint>
Use Examples 1-4, Comparative Use Examples 1-3
A water-based paint was obtained in the same manner as in the above embodiment except that the type of the aqueous suspension was variously changed.
Table 9 shows the main production conditions and various characteristics at this time.
[0158]
[Table 9]

[0159]
【The invention's effect】
In the aqueous suspension of lipidocrocite particles according to the present invention, each of the dispersed lipidocrocite particles has a kamaboko plate shape (cuboid shape), and the individual suspension originates from a small amount of hardly soluble sulfur-containing iron salt. Dispersion is excellent because the particles of the particles are dissociated, and since the coloring power and hiding power are excellent due to the particle shape, the aqueous suspension type orange coloring with excellent uniform dispersion and dispersion stability As a material, it can be used suitably for water-based paints, water-based printing inks, water-based cement colorants and water-based cosmetics, and as a high-concentration aqueous suspension, it can be preferably used as a water-based lubricant for rolling steel sheets.
[Brief description of the drawings]
BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is an X-ray diffraction pattern of a lipidocrosite particle powder having a rectangular parallelepiped shape obtained in an embodiment of the invention.
FIG. 2 is an electron micrograph (× 30000) showing the particle structure of a lipidoclosite particle powder having a rectangular parallelepiped shape obtained in an embodiment of the invention.
3 is an X-ray diffraction pattern of the reaction product obtained in Comparative Example 2. FIG.
4 is an electron micrograph (× 30000) showing the particle structure of the reaction product obtained in Comparative Example 2. FIG.
5 is an X-ray diffraction pattern of the reaction product obtained in Comparative Example 7. FIG.
6 is an electron micrograph (× 30000) showing the particle structure of the reaction product obtained in Comparative Example 7. FIG.
7 is an X-ray diffraction pattern of a repidocrocite particle powder having a rectangular parallelepiped shape obtained in Example 6. FIG.
8 is an electron micrograph (× 30000) showing the particle structure of a repidocrocite particle powder having a rectangular parallelepiped shape obtained in Example 6. FIG.

Claims (5)

It consists of lepidochrosite particles having a kamaboko plate shape having a minor axis diameter of 0.045 to 0.5 μm, a major axis diameter of 0.05 to 1.0 μm, and a thickness of 0.001 to 0.3 μm. An aqueous suspension of lipidocrocite particles obtained by dispersing a powder of lipidocrocite particles having a shaft diameter geometric standard deviation value of 1.70 or less in an aqueous medium. It consists of lepidochrosite particles having a kamaboko plate shape having a minor axis diameter of 0.045 to 0.5 μm, a major axis diameter of 0.05 to 1.0 μm, and a thickness of 0.001 to 0.3 μm. An aqueous suspension of lipidocrocite particles in which a lipidocrocite particle powder having a geometric standard deviation value of an axial diameter of 1.40 or less is dispersed in an aqueous medium. The aqueous suspension of lipidoclosite particles according to claim 1 or 2, wherein the lipidoclosite particles dispersed in the aqueous suspension contain 0.05 to 10% by weight of phosphorus. A coating comprising one or more selected from Al oxide, Al hydroxide, Si oxide and Si hydroxide on the surface of the lipidocrosite particles dispersed in the aqueous suspension The aqueous suspension of lipidoclosite particles according to any one of claims 1 to 3, which has a layer. The aqueous suspension of lipidocrosite particles according to any one of claims 1 to 4, wherein a surfactant is attached to the particle surface of the lipidoclosite particles dispersed in the aqueous suspension.

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