KR101966239B1 - Rod-like Iron Oxide Particles and the Fabrication Method Thereof - Google Patents

Abstract

A method for manufacturing iron oxide particles according to the present invention is the method for manufacturing rod-type iron oxide nanoparticles exhibiting high-definition red color. The method for manufacturing iron oxide particles comprises steps of: a) supersaturating an iron precursor in a straight chain saturated alcohol solvent of C4 or more, to manufacture a supersaturated solution; and b) heating the supersaturated solution to produce rod-type iron oxide.

Description

Field of the Invention [0001] The present invention relates to a rod-like iron oxide particle,

The present invention relates to a rod-shaped iron oxide particle and a method for producing the same, and more particularly to a rod-shaped iron oxide particle having excellent red sharpness and being mass-producible by a simple and inexpensive process, and a method for producing the same.

Iron oxide nanoparticles are applicable to various fields such as battery electrode materials, gas sensors, organic reaction catalysts, water decomposition catalysts, and MRI contrast agents. In addition, they are attracting attention as substitutes for red organic pigments as inorganic pigment particles.

These iron oxide nanoparticles are mainly produced by coprecipitation, pyrolysis, hydrothermal reaction, microemulsion and the like, but these production methods are not suitable for mass production of rod-shaped iron oxide particles having a length of several hundred nanometers.

As a method for producing iron oxide particles, a method of producing elliptical particles by using a strong base for inducing a condensation reaction as disclosed in Korean Patent Publication No. 10-1560441, and a method of producing iron oxide precursor A method of hydrothermally reacting an aqueous solution containing an alkali to prepare a platelet-shaped iron oxide, a method of producing an iron oxide pigment from a pickling waste liquid by electrolytic plating as disclosed in Korean Patent Publication No. 10-1266443, A large amount of harmful substances are discharged, resulting in poor commercial quality and a low shortening ratio of the particles to be produced is also low.

Korean Patent Publication No. 10-1560441 Korean Patent Publication No. 10-1026361 Korean Registered Patent No. 10-1266443

An object of the present invention is to provide a rod-shaped iron oxide particle having excellent red sharpness.

Another object of the present invention is to provide a method for producing a rod-shaped iron oxide particle having an excellent red sharpness and being mass-producible by a simple and inexpensive process.

The process for preparing iron oxide particles according to the present invention comprises the steps of: a) supersaturation of an iron precursor in a straight chain saturated alcohol solvent of C4 or higher to prepare a supersaturated solution; And b) heating the supersaturated solution to produce a bar-shaped iron oxide.

In the method for producing iron oxide particles according to an embodiment of the present invention, in the step b), the supersaturated solution may be heated to a temperature of 70 ° C or higher.

In the process for preparing iron oxide particles according to an embodiment of the present invention, the alcohol solvent may have a carbon number of C4 to C10.

In the method for producing iron oxide particles according to an embodiment of the present invention, the supersaturated solution may contain, per 100 g of the solvent, 1.1 to 1.8 times, based on the solubility at room temperature (g / 100 g alcohol solvent) of the iron precursor of the alcohol solvent Of iron precursors.

In the method of preparing iron oxide particles according to an embodiment of the present invention, the reaction of step b) may be carried out at a temperature lower than the boiling point (캜) of the solvent for 4 to 7 hours.

The method of producing iron oxide particles according to an embodiment of the present invention may further include the step of, after the step b), heat treating the bar-shaped iron oxide obtained in the step b) to produce a hematite structure of iron oxide .

In the method of manufacturing iron oxide particles according to an embodiment of the present invention, the heat treatment temperature may be 300 to 500 ° C.

In the method of preparing iron oxide particles according to an embodiment of the present invention, the iron precursor may be FeCl ₂ , FeCl ₃ , FeF ₂ , FeF ₃ , FeBr ₂ , FeBr ₃ , FeI ₂ , FeI ₃ , Fe (NO ₃ ) ₂ , Fe (NO ₃ ) ₃ , FeSO ₄ , Fe ₂ (SO ₄ ) ₃ , and hydrates thereof.

In the method for producing iron oxide particles according to an embodiment of the present invention, the average diameter of short axis of the rod-shaped iron oxide may be 5 to 50 nm and the average long axis length may be 200 to 1000 nm.

The present invention includes iron oxide particles produced by the above-described production method.

The iron oxide particles according to the present invention are characterized in that the iron oxide particles having an average minor axis diameter of 5 to 10 nm and an average major axis length of 200 to 1000 nm are bound together in the long axis direction to form a bundle, the average minor axis diameter of the bundles is 30 to 200 nm, May have an average major axis length of 200 to 1000 nm.

The iron oxide particles according to the present invention are aggregates having a hematite structure, an average short axis diameter of 20 to 50 nm and an average major axis length of 200 to 1000 nm, and the average short axis diameter of the agglomerates is 30 to 200 nm and an average major axis length of 200 to 1000 nm, and L * according to the CIE-Lab colorimeter may be 38 or more, a * may be 35 or more, and b * may be 30 to 33.

The present invention includes a red pigment containing iron oxide particles produced by the above-described production method.

The present invention includes a red pigment containing the iron oxide particles described above.

The iron oxide particles according to the present invention are rod-shaped iron oxides having a very high aspect ratio and have a structure in which the rod-shaped iron oxides are bound or agglomerated in the longitudinal direction, .

The method for producing iron oxide particles according to the present invention is a method for mass production of iron oxide particles exhibiting a high redness of red color through a very simple, economical, and commercially superior method of mixing an alcohol solvent and an iron precursor and remarkably low temperature heating There are advantages. Further, the process for preparing iron oxide particles according to the present invention does not require a base, a surfactant, or the like, that is, the reaction liquid can be composed of only an alcohol solvent and an iron precursor, and a reaction condition of a closed reactor or high temperature and high pressure is not required , It is easy to construct and manage the process, and the waste liquid generated after the reaction does not contain an acid, a base, an organic matter and the like, so that it is easy to treat the waste liquid and is an eco-friendly process.

1 is a process diagram showing a manufacturing process according to an embodiment of the present invention,
2 (a) and 2 (b) show scanning electron micrographs (FIG. 2 (a) and 2 (b)) of the powders produced in Example 1,
FIG. 3 is a scanning electron microscope (FIG. 3 (a)) and a transmission electron microscope (FIG. 3 (b)) of the powder prepared in Example 2,
Fig. 4 is a graph showing the results of X-ray diffraction analysis of powders prepared in Example 1 (Fig. 4 (a)) and Example 2 (Fig. 4 (b)
5 (a)) using 1-propanol as a solvent, Comparative Example 2 (Fig. 5 (b)) using 1-propanol as a solvent, Example 3 5 (c)) and Example 4 using 1-octanol as a solvent (Fig. 5 (d)),
6 shows a comparison example 3 (Fig. 6 (a)) using a solution in which the degree of supersaturation was 0.46, a comparative example 4 (Fig. 6 (b)) using a solution in which the degree of supersaturation was not saturated to 0.80, 6 (c)) and Example 6 (Fig. 6 (d)) using a supersaturated solution having a supersaturation degree of 1.71, which is a scanning electron micrograph of the iron oxide powder prepared in Example 5
7 is a scanning electron microscope (SEM) image of a powder prepared in Example 7 (FIG. 7 (a)) at 80 ° C and Example 8 (FIG. 7 ,
8 is a scanning electron microscope (SEM) image of the powder prepared in Comparative Example 6 in which the reaction was carried out using a saturated solution remained in an un-dissolved state of the iron precursor.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, iron oxide particles according to the present invention and a method for producing the same will be described in detail with reference to the accompanying drawings. The following drawings are provided by way of example so that those skilled in the art can fully understand the spirit of the present invention. Therefore, the present invention is not limited to the following drawings, but may be embodied in other forms, and the following drawings may be exaggerated in order to clarify the spirit of the present invention. Hereinafter, the technical and scientific terms used herein will be understood by those skilled in the art without departing from the scope of the present invention. Descriptions of known functions and configurations that may be unnecessarily blurred are omitted.

The process for preparing iron oxide particles according to the present invention comprises the steps of: a) supersaturation of an iron precursor in a straight chain saturated alcohol solvent of C4 or higher to prepare a supersaturated solution; And b) reacting the supersaturated solution at a temperature of 70 캜 or higher to produce a rod-shaped iron oxide.

According to the production method of the present invention, when a supersaturated solution is prepared by supersaturation of an iron precursor in a straight chain saturated alcohol solvent of C4 or higher, and the solvent is thermally reacted at a temperature of 70 ° C or higher, a rod shape having an average major axis length of 200 to 1000 nm And a rod-shaped iron oxide having high redness and high redness can be produced.

FIG. 1 is a process diagram showing a manufacturing method according to an embodiment of the present invention. As shown in FIG. 1, a manufacturing method according to an embodiment of the present invention includes a supersaturated solution producing step (s100) The method may further include a heat treatment step (s300) for improving the crystallinity of the rod-shaped iron oxide obtained in the solvent thermal reaction step (s300), if necessary, including the step (s200).

 Specifically, in the supersaturated solution preparation step (s100), the solvent of the iron precursor may be a straight chain saturated alcohol having C4 or more, specifically a straight chain saturated alcohol having C4 to C10 carbon atoms, The chain saturated alcohols may be 1-butanol, 1-pentanol, 1-hexanol, 1-heptanol, 1-octanol, 1-nonanol, 1-decanol or mixtures thereof. Bar-shaped iron oxides can be produced which exhibit high-definition red color only when the solvent is a straight chain saturated alcohol having a C4 or higher solvent together with the supersaturation requirement. That is, in the case of using a low-alcohol solvent or a non-saturated or non-saturated alcohol solvent other than C3, which is not a straight chain saturated alcohol having a C4 or higher, and an iron-based precursor is in a supersaturated state in a solution, Or sea urchin iron oxide is produced.

In the supersaturated solution preparation step (s100), the iron precursor may be an iron salt which is easily soluble in a solvent which is a straight chain saturated alcohol of C4 or more. However, iron precursors can be selected from the group consisting of FeCl ₂ , FeCl ₃ , FeF ₂ , FeF ₃ , FeBr ₂ , FeBr ₃ , FeI ₂ , Fe ₃ O ₃ , Fe ₂ O ₃ , ₂ , FeI ₃ , Fe (NO ₃ ) ₂ , Fe (NO ₃ ) ₃ , FeSO ₄ , Fe ₂ (SO ₄ ) ₃ and hydrates thereof. But is not limited thereto.

The supersaturated solution can be prepared by adding an iron precursor to a solvent that is a straight chain saturated alcohol having a C4 or higher melting point above room temperature solubility limit and stirring. The iron precursor solution must be a supersaturated solution for the production of rod-shaped iron oxides which exhibit a high-definition red color, together with a solvent which is a straight chain saturated alcohol of C4 or higher.

Specifically, the supersaturated solution preferably contains 1.1 times or more of the iron precursor based on the room temperature solubility (S) of the iron precursor of the solvent, which is a straight chain saturated alcohol of C4 or more. The mean solubility at room temperature means the maximum number of iron precursors dissolved in 100 g of solvent at room temperature (25 ° C.) and atmospheric pressure (1 atm). The meaning of containing iron precursors of 1.1 times or more based on solubility means that 100 g It is understood that it means that the iron precursor is contained at 1.1 times or more the solubility at room temperature. This means that the supersaturation of the supersaturated solution is 1.1 times or more when supersaturation is defined as a value obtained by dividing the iron precursor mass contained in the solution per 100 g of the solvent in the supersaturated solution by the solubility at room temperature of the iron precursor. If the supersaturation of the supersaturated solution is less than 1.1 times, there is a danger that spherical or urchin-shaped iron oxides may be produced even if straight-chain saturated alcohols of C4 or higher are used as the solvent. In addition, when the supersaturation degree of the supersaturated solution is excessively high, it is difficult to stably maintain a high supersaturation degree during the manufacturing process, and the reproducibility of the process is deteriorated. Thus, the supersaturated solution preferably contains an iron precursor in an amount of 1.1 to 2.0, specifically 1.1 to 1.8 times, based on the solubility at room temperature of the iron precursor of the solvent per 100 g of the solvent of the supersaturated solution.

 The supersaturated solution production step (s100) may be performed at a temperature at which no solvent thermal reaction occurs, specifically at 15 to 30 ° C, more specifically at a temperature of 20 to 25 ° C. Specifically, the preparation of the supersaturated solution is carried out by adding an iron precursor to the straight chain saturated alcohol having a C4 or higher temperature at a temperature of 15 to 30 ° C, more specifically 20 to 25 ° C, so as to satisfy the supersaturation degree described above, To be in a supersaturated state. In a practical, non-limiting example, the supersaturated solution is heated to a temperature of from 15 to 30 ° C, more specifically from 20 to 25 ° C, to a straight chain saturated alcohol having a C4 or higher saturation alcohol concentration of 1.5 to 4 hours ≪ / RTI > and stirring.

After the supersaturated solution production step (s100) is performed, a solvent thermal reaction step (s200) in which the supersaturated solution is heated and reacted may be performed. The solvent thermal reaction step may be performed by heating the supersaturated solution prepared in step s100 to a temperature of 70 DEG C or higher, and may be heated and reacted in an atmospheric air atmosphere. Specifically, the supersaturated solution can be heated to a temperature below 70 ° C and below the boiling point of the solvent, which is a straight chain saturated alcohol of C4 or higher in a supersaturated solution, and can be heated to a temperature substantially between 70 ° C and 110 ° C.

If the heating temperature of the supersaturated solution for the solvent thermal reaction is less than 70 캜, the reaction itself may not occur and the iron oxide particles may not be produced. As described above, the solvent thermal reaction can be accompanied by heating at 70 DEG C or higher, and a rod-shaped Iron oxide can be produced. Amorphous micro-nuclei (seeds) are formed at the initial stage of the reaction in the heat of the solvent, and the microcracks grow unidirectionally as the reaction progresses. Therefore, in order to stably ensure micro nucleation and growth of nuclei, the reaction time during the thermal reaction of the solvent is preferably 4 to 7 hours. However, the present invention is not limited by the reaction time, Considering the change and the degree of suspension, it is sufficient that the reaction is performed for a sufficient time to complete the particle generation by the solvent thermal reaction.

By the above-described production method, a rod-shaped iron oxide having an average short axis diameter of 5 to 50 nm and an average long axis length of 200 to 1000 nm can be produced. Specifically, by a solvent thermal reaction in which the iron precursor is supersaturated with a solvent which is a straight chain saturated alcohol of C4 or more, the average minor axis diameter is 5 to 10 nm and the average major axis length is 200 to 1000 nm, specifically 200 to 500 nm. Bar iron oxide can be produced, and a bundle-type iron oxide particle in which such micro-scale iron oxide is bound to each other in the longitudinal direction (long axis direction) of the rod can be produced.

The average particle diameter (short axis diameter of the bundle) of the bundled iron oxide particles may be 30 to 200 nm, and the average major axis length (bundle length) may be 200 to 1000 nm. At this time, as the micro-scale iron oxide is bound to each other in the longitudinal direction to form bundles, the long axis length (bundle length) of the bundle-type iron oxide particles may be similar to the length of the microfilm iron oxide.

After completion of the above-described thermal reaction of the solvent, the rod-shaped iron oxide produced by the ordinary solid-liquid separation such as centrifugation, filtration and the like can be separated and recovered. It is also possible to use a solvent such as water which does not react with iron oxide It is a matter of course that washing can be performed.

Thereafter, as shown in Fig. 1, if necessary, a heat treatment step (s300) for improving the crystallinity of the rod-shaped iron oxide obtained in the solvent thermal reaction step (s300) may be further performed. The slightly crystallized ferrooxidized iron may be prepared according to the solvent thermal reaction in step s200. Then, the step (s300) of producing the hematite structure of the bar-shaped iron oxide by heat-treating the bar-shaped iron oxide obtained in the step s200 can be further performed. At this time, the heat treatment temperature may be 300 to 500 ° C in terms of improvement in crystallinity (improvement in crystallinity to the hematite structure), but it is preferable to change the heat treatment temperature appropriately so as to have a desired crystal structure based on the thermodynamically stable iron oxide structure Of course.

The ferrooxidized iron obtained by the reaction of step s200 can be sintered at the same time the crystallinity is improved by the heat treatment at step s300. Thus, by the heat treatment in step s300, a highly crystalline, rod-shaped iron oxide having a hematite structure can be obtained. The average short axis diameter is 20 to 50 nm and the average major axis length is 200 to 1000 nm, specifically 200 Lt; RTI ID = 0.0 > 500nm < / RTI > As described above, as the bundle-shaped particles in which the rod-shaped iron oxides are bound to each other in the major axis direction by the step (s200) are obtained as described above, the bundle shape at the time of heat treatment is substantially maintained by the sintering Agglomerates in which the grown iron oxides are bound to each other can be produced. The aggregate may have an average minor axis diameter of 30 to 200 nm and an average major axis length of 200 to 1000 nm, and may have substantially the same shape (macroscopic shape) and size as the bundle shape described above.

That is, a bundle-type iron oxide particle in which the micro-scale iron oxide is bound to each other in the longitudinal direction (the major axis direction) of the rod can be produced by the solvent thermal reaction, and the iron oxide particles produced by the solvent heat reaction The size and shape of the iron oxide particles in the form of a bundle are maintained as they are but the sintering of the fine iron oxide is caused and agglomerates of the iron oxide can be produced.

The present invention includes iron oxide particles produced by the above-described production method. At this time, the iron oxide particles may include the above-mentioned rod-shaped iron oxide, a bundle of rod-shaped iron oxide, or agglomerates of the rod-shaped iron oxide.

The iron oxide particles according to an embodiment of the present invention have a mean diameter of short axis of 30 to 200 nm and a mean diameter of short axis of 30 to 200 nm, wherein the iron oxide particles have an average short axis diameter of 5 to 10 nm and an average long axis length of 200 to 1000 nm, , And the average major axis length of the bundle may be 200 to 1000 nm.

The iron oxide particles according to another embodiment of the present invention is an aggregate having a hematite structure, an average short axis diameter of 20 to 50 nm and an average major axis length of 200 to 1000 nm, The average short axis diameter is 30 to 200 nm and the average long axis length is 200 to 1000 nm. The L * according to the CIE-Lab colorimeter may be 38 or more, the a * may be 35 or more, and the b * may be 30 to 33. Specifically, the iron oxide particles may have L * of 38 to 45, a * of 35 to 40 and b * of 30 to 33 according to the CIE-Lab colorimeter.

At this time, the CIE-Lab value refers to a value according to a standard colorimetric system prescribed by CIE (International Lighting Commission), and specifically refers to a CIE-Lab value according to a color difference meter. In general, the color can be represented by L * value, a * value and b * value (CIE-Lab value) defined by CIE (International Lighting Commission) Brightness, saturation and color. As is known, the L * value represents lightness and is displayed from 0 to 100. The a * value and the b * value are the normal coordinates (xy-coordinate) of the color difference meter, the abscissa is the a * value, This is the b * value. In this case, the a * value is a spectrum from green to red. The + a side is red, the -a side is green, and the a * value is a value ranging from -120 to +120. do. In addition, the b * value is a blue to yellow spectrum with a + b value close to yellow and a -b value close to blue value, and a value of -120 to +120 . ≪ / RTI >

The present invention includes a red pigment containing the iron oxide particles described above.

(Example 1)

300 g (243 g) of 1-butanol as a solvent and 300 g of Fe (NO ₃ ) ₃ .9H ₂ O as an iron precursor were added to a 1 L glass flask and stirred at room temperature for 2 hours to prepare a supersaturated solution. The solubility of Fe (NO ₃ ) ₃ .9H ₂ O in 1-butanol at room temperature was 87.65 (g / 100 g of butanol), and the degree of supersaturation of the supersaturated solution was 1.41.

The supersaturated solution was then heated to 70 DEG C and stirred at 70 DEG C for 5 hours to carry out the reaction. In the heating reaction, an opaque suspension of dark yellow was prepared in an initial brown, transparent supersaturated solution. After completion of the heating reaction, the synthesized particles were recovered by centrifugation using water, and the recovered particles were washed twice with water. Thereafter, the water-washed particles were dried in an oven at 60 DEG C for 12 hours to prepare a powder.

(Example 2)

The powder prepared in Example 1 was heat treated in air at 400 ° C for 3 hours.

(Example 3)

Powder was prepared in the same manner as in Example 1, except that a supersaturated solution having a supersaturation degree of 1.59 was prepared by using 1-hexanol instead of 1-butanol as a solvent.

(Example 4)

In Example 1, a powder was prepared in the same manner as in Example 1, except that a supersaturated solution having a supersaturation degree of 1.80 was prepared using 1-octanol instead of 1-butanol as a solvent.

(Example 5)

A powder was prepared in the same manner as in Example 1, except that 243 g of the iron precursor in Example 1 was used instead of 300 g of the iron precursor to prepare a supersaturated solution having a supersaturation degree of 1.14.

(Example 6)

In Example 1, powder was prepared in the same manner as in Example 1, except that 365 g was used instead of 300 g of the iron precursor to prepare a supersaturated solution having a supersaturation degree of 1.71.

(Example 7)

In Example 1, powders were prepared in the same manner as in Example 1, except that the supersaturated solution was heated to 80 ° C instead of 70 ° C.

(Example 8)

In Example 1, a powder was prepared in the same manner as in Example 1, except that the supersaturated solution was heated to 110 ° C instead of 70 ° C.

(Comparative Example 1)

A powder was prepared in the same manner as in Example 1, except that ethanol was used in place of 1-butanol as a solvent.

(Comparative Example 2)

In Example 1, a powder was prepared in the same manner as in Example 1, except that 1-propanol was used instead of 1-butanol as a solvent.

(Comparative Example 3)

Powder was prepared in the same manner as in Example 1, except that 97 g of iron precursor was replaced with 300 g of iron precursor and a solution whose saturation degree was not saturated to 0.46 was prepared.

(Comparative Example 4)

In Example 1, a powder was prepared in the same manner as in Example 1, except that 170 g of iron precursor was used instead of 300 g of the iron precursor, and a saturated solution was prepared with a degree of supersaturation of 0.80.

(Comparative Example 5)

In Example 1, a powder was prepared in the same manner as in Example 1, except that the supersaturated solution was heated to 60 ° C instead of 70 ° C.

(Comparative Example 6)

In Example 1, a powder was prepared in the same manner as in Example 1 except that the same amount of the solvent and the iron precursor were mixed, but a saturated solution in which the undissolved iron precursor remained was not produced.

FIG. 2 is a scanning electron microscope (FIG. 2 (a)) and a transmission electron microscope (FIG. 2 (b)) observing the powder produced in Example 1. As can be seen from a high-magnification transmission electron microscope photograph, it can be seen that a bundle-type particle having a bundle of bundles of rod-shaped iron oxides having an average diameter of 7 nm and a length of 200 to 500 nm was produced. It can be seen that a multicomponent particle having a diameter of 95 nm and a length of 200 to 500 nm similar to that of the rod-shaped iron oxide is produced.

FIG. 3 is a scanning electron microscope (FIG. 3 (a)) and a transmission electron microscope (FIG. 3 (b)) observing the powder produced in Example 2. As can be seen in FIG. 3, it can be seen that the bundle shape is maintained even after the heat treatment, and the length is 200 to 500 nm and the average diameter is about 95 nm, which is substantially the same size as the particles before heat treatment. However, it can be seen from the transmission electron microscope photograph of FIG. 3 (b) that as the rod-shaped iron oxide is sintered in the heat treatment at 400 ° C., the diameter of the rod is increased to about 30 nm on average.

4 is a graph showing the results of X-ray diffraction analysis of powders prepared in Example 1 (Fig. 4 (a)) and Example 2 (Fig. 4 (b)). 4 (a), it can be confirmed that the crystallinity is lowered by solvent thermal synthesis but the main peak of hematite is observed, and it can be seen that low crystallinity iron oxide having a hematite structure is produced. 4 (b), a highly crystalline hematite structure (Hematite, JCPDS card no. 33-0664) with a relative intensity intensity at peak positions and peaks coincides with the reference material hematite It can be seen that iron oxide powder is produced.

The CIE-Lab values of the iron oxide powders prepared in Example 2 were 39.91 for L *, 36.04 for a * and 32.64 for b * using a colorimeter, and the red iron oxide particles having excellent sharpness were produced Respectively.

Table 1 below shows the CIE-Lab values of commercially available iron oxide pigments (Commercial Pigment A and Commercial Pigment B) commercially available as iron oxide powder and red pigment prepared in Example 1.

(Table 1)

As can be seen from Table 1, the prepared iron oxide powder has a very good red sharpness and a high brightness.

5 (a)) using 1-propanol as a solvent, Comparative Example 2 (Fig. 5 (b)) using 1-propanol as a solvent, Example 3 5 (c)) and Example 4 using 1-octanol as a solvent (Fig. 5 (d)).

As can be seen from FIG. 5, in ethanol and 1-propanol having 3 or less carbon atoms, spherical particles that are not rod-shaped aggregates are produced. However, 1-hexanol and 1-octanol, which have a carbon number of 4 or more and a straight chain saturated alcohol It can be seen that particles are produced in the form of bundles of rod-shaped iron oxides similarly to the particles of Example 1 using 1-butanol, and the length and diameter are also similar to those of Example 1 have. Through Examples 1 to 4 and Comparative Examples 1 to 2, it was found that to prepare the multimolecular particles in which the rod-shaped iron oxide and the rod-shaped iron oxide were bound to each other in the major axis direction, the number of carbon atoms of 4 or more, Chain saturated alcohol should be used as a solvent.

6 shows a comparison example 3 (Fig. 6 (a)) using a solution in which the degree of supersaturation was 0.46, a comparative example 4 (Fig. 6 (b)) using a solution in which the degree of supersaturation was not saturated to 0.80, (FIG. 6 (c)) using a solution and a supersaturated solution having a supersaturation degree of 1.71 (Example 6 (FIG. 6 (d)).

As can be seen from FIG. 6, it can be confirmed that, even when a supersaturated solution is used, even if a straight chain saturated alcohol having a C4 or higher is used as a solvent, a spherical particle phase is only produced, and a supersaturated solution having a supersaturation of 1.14 or more It can be seen that only in the case of Example 1, bundle-type particles comprising bundles of rod-shaped iron oxide and rod-shaped iron oxide are produced.

7 is a scanning electron microscope (SEM) image of a powder prepared in Example 7 (FIG. 7 (a)) at 80 ° C and Example 8 (FIG. 7 As can be seen from FIGS. 2 and 7, when the supersaturated solution is reacted at a temperature of 70 ° C. or higher and a boiling point of the solvent (boiling point of butanol = 117.7 ° C.), the rod-shaped iron oxide and the rod- It can be seen that a bundle-shaped particle is produced.

However, in the case of Comparative Example 5 in which the reaction was carried out at 60 ° C, it was confirmed that no suspension was produced even after the reaction proceeded for 12 hours or more, and no particles were observed in the scanning electron microscopic analysis after the reaction.

8 is a scanning electron microscope (SEM) image of the powder prepared in Comparative Example 6 in which the reaction was carried out using a saturated solution remained in an un-dissolved state of the iron precursor. As can be seen from FIG. 8, when a saturated solution in which an iron precursor acting as a nucleus remains is used, it can be confirmed that globular spherical particles are produced.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, Those skilled in the art will recognize that many modifications and variations are possible in light of the above teachings.

Accordingly, the spirit of the present invention should not be construed as being limited to the embodiments described, and all of the equivalents or equivalents of the claims, as well as the following claims, belong to the scope of the present invention .

Claims (12)

a) supersaturation of the iron precursor in a straight chain saturated alcohol solvent of C4 or higher to produce a supersaturated solution; And
b) heating the supersaturated solution to produce a bar-shaped iron oxide;
/ RTI >
Wherein the supersaturated solution contains 1.1 to 1.8 times the iron precursor based on the solubility at room temperature (g / 100 g alcohol solvent) of the iron precursor of the alcohol solvent per 100 g of the solvent. The method according to claim 1,
In step b), the supersaturated solution is heated to a reaction temperature of 70 ° C or higher. The method according to claim 1,
Wherein the alcohol solvent has a carbon number of C4 to C10. delete The method according to claim 1,
Wherein the heating in step b) is carried out at a temperature lower than the boiling point (占 폚) of the solvent for 4 to 7 hours. The method according to claim 1,
It said iron precursors include _{FeCl 2, FeCl 3, FeF 2} , FeF 3, FeBr 2, FeBr 3, FeI 2, FeI 3, Fe (NO 3) 2, Fe (NO 3) 3, FeSO 4, Fe 2 (SO 4 ) ≪ ₃ >, and hydrates thereof. The method according to any one of claims 1 to 3 and 5 to 6,
Further comprising the step of: after the step b), heat treating the bar-shaped iron oxide obtained in the step b) to prepare a bar-shaped iron oxide having a hematite structure. 8. The method of claim 7,
Wherein the heat treatment temperature is 300 to 500 占 폚. The method according to any one of claims 1 to 3 and 5 to 6,
Wherein the average diameter of the minor axis of the rod iron oxide is 5 to 50 nm and the average major axis length is 200 to 1000 nm. Wherein the rod-shaped iron oxides having an average short axis diameter of 5 to 10 nm and an average long axis length of 200 to 1000 nm are bound together in a long axis direction to form a bundle, the average short axis diameter of the bundles is 30 to 200 nm, Iron oxide particles having a thickness of 1000 nm. An agglomerate having a hematite structure, an average short axis diameter of 20 to 50 nm and an average major axis length of 200 to 1000 nm, the aggregate having an average short axis diameter of 30 to 200 nm and an average long axis length Is 200 to 1000 nm, and has an L * of 38 or more, a * of 35 or more, and b * of 30 to 33 according to a CIE-Lab colorimeter. A red pigment containing iron oxide particles according to claim 10 or 11.

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