JPS5849693A - Yellow pigment of iron oxide - Google Patents

Abstract

PURPOSE:To prepare yellow pigment of iron oxide like grains of rice, having improved color tone, dispersibility, and heat resistance, by adding an aqueous solution of a ferric salt to an alkali aqueous solution at a specific temperature to give iron hydroxide, aging it, subjecting it to hydrothermal treatment at a specified temperature. CONSTITUTION:An aqueous solution of a ferric salt at <=30 deg.C is added to an alkali aqueous solution at <=30 deg.C to prepare iron hydroxide. Ferric sulfate, etc. is used as the iron salt, its concentration is <=0.5M/l, sodium hydroxide, etc. is used as the alkali, its concentration is <=4M/l, and the reaction is carried out at -5-30 deg.C. The prepared precipitate of iron hydroxide is aged for >=30min, subjected to hydrothermal treatment at 120-250 deg.C for about 1hr, so that iron oxide hydroxide like grains of rice, namely, yellow iron oxide pigment is prepared. The long axis of the yellow iron oxide pigment like grains of rice is in 100-350mm., a ratio of long axis/short axis is 1.5-4.5, and the pigment has improved color tone, dispersibility and stability as pigment.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention also relates to a planar iron oxide pigment having a narrow f6 degree distribution width and a method for producing the same. The purpose of this is to
By providing yellow iron oxide pigments with excellent dispersibility and heat resistance, we are further expanding the range of conventional uses and developing new uses for heat-processing resins, cosmetics, and traffic paints.

Currently, yellow pigments include yellow lead, strondium yellow, cadmium yellow, and benzinone 611.

All of these are toxic or emit 11i'i f/l, so protection against environmental staining 11. Naturally, the use of karazo has been regulated due to the National Health Order.

In view of this situation, the development of an excellent non-toxic yellow pigment in place of the toxic yellow pigments is eagerly awaited in the coloring industry.

Yellow iron oxide has the composition α-1i' e 00 summer I.
It has an oethitc structure and is called goethite, ocher, ocher, etc., and has been used as colored paulownia wood since ancient times.

It is non-toxic, non-toxic, stable and inexpensive. Its uses range from paints, printing inks, and construction feeds to coloring cosmetics, cigarette filter paper, and poultry feed because it is nontoxic. After the war, it also came to be used as a raw material for magnetic powder for magnetic recording, and demand for it has increased markedly as magnetic recording methods have progressed and spread. However, the quality of this card as a face number one is not satisfactory and there is a lot of room for change.

However, it has drawbacks such as a slightly unclear color tone, high viscosity due to the acicular grain shape, and poor thermal properties. For this reason, replacement with the above-mentioned toxic yellow pigment is limited, and there has been a strong demand for improving the properties and quality of this pigment for some time.

Currently, the method for producing yellow iron oxide is a method in which microcrystalline nuclei are grown to a desired diameter by applying hydrolysis of an aqueous solution of ferrous I:nj acid and an air oxidation reaction. ing. At this time, add a very mild ferrous sulfate aqueous solution to the crab.
1) There are two methods for promoting crystal growth: a method using iron scraps and a method using ammonia scum. 1) ii V
In l -), the example is, borrow question ka, king, friend, 4]2
(IQ 63) has a d child. Regarding the latter, Arrow 111, Elect [7 Nik Ceramics'72, l
fz, 1, l', ] 5 is described as -C. From these documents and Figures 3 and 4 of the latter, the conventional yellow iron oxide has a sword-shaped tactoid particle morphology, and its formation is related to crystal growth in an insoluble aqueous solution. From a mechanical point of view, it is extremely difficult to adjust the manufacturing conditions, and it is extremely difficult to obtain products with uniformity or uniformity. It is impossible to change the ratio. Therefore, currently commercially available yellow iron oxide has large particles, as shown in Figures 3 and 4. ) It shows a wide particle size distribution with a mixture of small A tables and 6 needles with the same axial ratio.

It is well known that the filling properties of a powder system are generally correlated with the particle morphology of the powder. In the case of pigments, the particle morphology affects the color tone, obscurity, oil absorption, coloring power, rheolocinol properties and strength of the coating film when used as a paint. In the case of yellow iron oxide, the mixture of large particles and small particles indicates that the physical properties of large particles and small particles are different, but as a powder, they exhibit physical properties as a systematic average in which they are mutually attenuated. It turns out. Taking color tones as an example, borrow questions, carpentry exam report, and sake cup 331. As described in P. 33 (Sho 44), the color shown by the large particles and the color shown by the small ladle are different, so any mismixing of these results in a subtractive color mixture, similar to the color mixing of paints, resulting in changes in lightness and saturation. As the intensity decreases, the color tone becomes darker. In other words, it is ideal for the pigment to be a powder with a narrow particle size distribution. Furthermore, there is a demand for a pigment with a small axis ratio of the acicular grain tops, good dispersibility, and low oil absorption.

Through many years of research on yellow iron oxide, the present inventors have understood its essential drawbacks, responded to the needs of the industry, conducted advanced research, and contributed to improving the quality of yellow iron oxide. For example, in patents (", Sahara, Borisoku, Tokuko Sho 3l-324)
2: Borrower, Asai, same litter, Tokuko Sho 53-28158: Borrower, Asai, same litter, [1, S.

Pat, 3,969,494: Borrow et al., Tokuko Sho 5
5-9016 etc. Some of these technologies have been contracted and implemented. This time, we have developed a new technology. They succeeded in changing the morphology of yellow iron oxide from needle-like to rice-grain-like and narrowing the particle size distribution. As a result, it was possible to improve the fillability, solid color tone, dispersibility, stability, etc. of the pigment as a pigment.

Next, the configuration of the present invention will be explained. First, an aqueous ferric salt dk is reacted with an aqueous alkaline solution to prepare an iron hydroxide precipitate. In this case, the iron salts used are water-soluble foreign iron J'AA such as ferric sulfate, ferric chloride, and ferric nitrate.

The concentration used is 0.5 M//' or less, preferably around 0.2 M/l. On the other hand, alkalis include sodium hydroxide, potassium hydroxide, thorium carbonate, potassium carbonate, and calcium hydroxide. The concentration used is
4 M 71 or less, preferably 1. It is near Mle. If the reaction is carried out at a concentration higher than a certain level, the product will be non-uniform and the particle size distribution will be widened, resulting in unfavorable results.

10. The iron salt aqueous solution and the alkaline aqueous solution are reacted at -5 to 30°C, and at this time, it is a necessary condition that the iron salt aqueous solution is added to the alkaline water. If this is done in reverse, the particle morphology of the 41" product will become acicular with a large axial ratio. Also, the temperature at which both liquids are reacted is determined by the R apex diameter of the product and the axial ratio of the particles. At temperatures above 30°C, the axial ratio becomes too large and tactoids tend to form.

The iron hydroxide precipitate prepared as described in -1- is aged for 30 minutes or more, preferably for about 1 day, and then subjected to the next hydrothermal treatment. This ripening results in a homogeneous, well-aligned grain top. The aged precipitate is subjected to hydrothermal treatment at a temperature ranging from 120 to 250°C, preferably at 180°C for about 1 hour. When the treatment temperature is low, it takes a long time for crystallization, and at a temperature higher than a certain level, red iron oxide α-1" C 20:3 is mixed. This hydrothermal treatment J↓!! Crystallization of the regular iron hydroxide precipitate is promoted, and grain-like iron oxide hydroxide α-FeOO11, that is, yellow iron oxide, is produced by dissolution and precipitation.

The summary of the invention is as in I--that is, the technology is concerned with the control of particle morphology.

The key point of this new technology was the preparation conditions for the initial stage of iron hydroxide precipitation. This series of technologies is a collection of combinations of conditions at each stage.

There are a huge number of combinations of conditions, but most of them yield ineffective results. However, since the theory regarding the adjustment of crystal morphology has not yet been established, useful results can only be expected by carefully experimenting with various conditions. Through many experiments, the inventors finally found that
We have found useful conditions for preparing yellow iron oxide in the form of rice TFT.

Next, the present invention will be explained using experimental examples. Tetsu `` Grape Toshite ''
Ferric island 1”cC15-6o,, o (7) 50
Hydroxylation as an alkali using 9/l aqueous solution (approximately 0.2 M/V)-1-IJ Lamb Na0r-1 Noah 5
A 9/2 l aqueous solution (approximately 1 M/A') is used. Both solutions were poured into a NaOH aqueous solution at -5 to 35°C.
A Cl 3 aqueous solution is added and a precipitation reaction is performed to prepare iron hydroxide precipitate. In this case, the excess free alkali concentration in the mother liquor is approximately 0.4. M/l. If this free alkali concentration is higher than IM/l, the ID particle morphology will be disrupted, so this is not preferable (7).

After aging the iron hydroxide precipitate with the mother liquor for 1 [1] time, it was heated to 180°C.
After hydrothermal treatment for about 1 hour, iron oxide hydroxide α-F e
001 I Zunawara yellow iron oxide is produced. Table 1 shows typical pigment properties of the results of this experiment, with the reaction temperature for precipitation being a variable.

From the results in Table 1, the higher the reaction temperature, the better the growth on both the long and short axes. However, since the growth of the long axis is greater than that of the short axis, it increases as the axial ratio increases by 1 degree. Then, the axial ratio increases rapidly from around 30°C. The specific surface area is approximately proportional to the oil absorption amount, and a smaller one is preferable, but it is not preferable when dispersing C'A because the axial ratio of the particles increases and the bulk increases. The sedimentation volume and bulk (increasing in proportion to the four-dimensional ratio).The hidden force increases in proportion to the short axis of the particle.As for the relationship between the needle-like structure and pigment properties, Borrowed questions, carpentry exam report, I
(x331, P, 35 (1969): Borisoku, Attitude, Asai, Coloring Materials Research Presentation Meeting (] 980) reported in detail.In general, pigment characteristics - L1 particles are spherical with the smallest surface energy. This is ideal.In the case of acicular grains, the color tone and hidden spectra are mainly controlled by the short axis (width).From the results in Table 1, the grain top shape is rice grain-like.
This is the case when the reaction temperature is 30°C or lower, especially -5°C to 2°C.
It is suitable as a pigment in the range of 0°C or with an axial ratio of about 3 or more.

Used in one color paulownia wood and one color for face, cow paste, printing ink, cosmetics, etc. Therefore, the tone,
There are two important aspects of dispersion into the vehicle and surface properties.In the case of yellow iron oxide, the color tone changes depending on the minor axis diameter of f-F. In other words, there is a correlation between the minor axis diameter and brightness. Iron oxide (4) has a brightness of 71", which is about 100% for practical use. There are various types depending on the purpose. In fact, each company has several types available as products ("). Hidden pay/J depending on the size of the short axis E η
The thick pigments are very bright and have a large brightness. The smaller one of this (J, 1) is used as a transparent LIII pigment (o-@panty) because it brings clarity (1).

The dispersibility of the vehicle '\ for Face Ne・1 (as mentioned in 1, 1, spherical particles exhibiting the minimum surface energy are the best -C') Of course, in the case of yellow iron oxide, there is still a A method for synthesizing spherical nets has not yet been invented.The present inventors have modified the conventional sword-shaped powder into rice-grain-shaped powder and improved its properties. It is similar to when considering the link as a powder and comparing the characteristics of the part 11 in the vehicle.The former is bulky and entangled and difficult to disperse, but the latter is low in bulk and easy to disperse. Iron oxide has a lower oil absorption, lower bulk, and easier dispersion than needle-like materials of the same color.It also has a low viscosity when dispersed.These are very desirable properties as a pigment. Thermal properties are inherent to the compound, but in the case of pigments, it is dependent on the homogeneity of the powder,
Crystallinity and particle size distribution are not affected.

The yellow iron oxide of the present invention is particularly excellent in these respects because it is completely crystallized by hydrothermal treatment as described above.

Next, the present invention will be explained in more detail with reference to Examples.

Example I Fe C/3 ・51-12050'i/z and N
a Prepare aqueous solutions of OlT 7 s/21 and cool both solutions to -2°C. Then, while stirring well, add F e CI! into the Na Otl aqueous solution. 3 aqueous solution is gradually added to form a Fe'(O12)3 precipitate.

The liquid temperature after precipitation is approximately 0°C. This precipitate is aged with the mother liquor while stirring occasionally. The settling volume of the precipitate after aging is approximately 250 mI! Therefore, 1. The clear liquid is discarded, and approximately 300 rnl of the precipitate containing the rJ liquid is transferred to a Teflon beaker, placed in an autoclave, and subjected to hydrothermal treatment at 180°C for 60 minutes. The pressure at this time is the saturation pressure of water vapor.

Through this treatment, the amorphous Fe (011) 3 tricolor precipitate is completely crystallized and turns into a crystalline yellow precipitate.

When this was washed with water, the settling volume of the precipitate was as low as 150 lll1. [〃] When it is filtered and dried, a yellow iron oxide in the form of rice hydroxide α-1·eooH is obtained.

The pigment properties of this are as follows. f Tablet diameter, long axis:
l 34 nn1. Minor axis: 55 nm, axial ratio: 2.4.
Specific surface area: 35 nt / 9, hidden crab 53
0 t: f/g, Yield: i5S', Sedimentation volume: 1
oml/g, (see Figure 1).

Example 2 Fe2(504)3 369/l and Na0117
Aqueous solutions of 5p and /2I are prepared respectively, and both solutions are cooled to 9°C. Then, while stirring well, Na011
A li'e2(SO4)3 aqueous solution is gradually added to the aqueous solution to form an F c (OTI) 3 precipitate. The liquid temperature after the precipitation is about 10°C. Hereinafter, yellow iron oxide in the form of rice Ct was obtained using exactly the same method as in Example 1. This face is Neroro! The i-character is as follows. Particle diameter, major axis: 1
．． 94. nm.

Short axis: 70 nm, axial ratio = 28. Specific surface bond: 3
Q nf/g, hidden pay crab 580ca/9. Collection: ]
59゜Example 3 Fc (No3): 31g1120 75'i/
l and ■ζ0I11.00g/27? Prepare aqueous solutions of 1-1 and keep both solutions at 19°C. Soshi-
〇, Stir well.
NO3)r3 Gradually add the aqueous solution 1~, I”c (
011): Make a precipitate. Liquid temperature after precipitation (1 approx. 2
It becomes 0℃. Thereafter, semi-cylindrical yellow iron oxide was obtained in exactly the same manner as in Example 1. The pigment properties of this are as follows. Particle diameter, long axis: 266 nm, short axis: 82
nm, ratio: 32. Specific surface bond: 26 nf/
7. Hidden pay crab 920cn/! , Collection: 16! i/,
(See Figure 2).

[Brief explanation of drawings]

1 and 2 are electron micrographs of a yellow iron oxide pigment obtained by the method of the present invention at a magnification of 4.0,000 times. Figure; 3 and 4 show the conventional yellow iron oxide surface *-1 of 40,
0 (This is an electron micrograph at a magnification of 10.
Man

Claims (1)

[Claims] 1. Yellow iron oxide having an ellipsoidal (rice grain-like) particle shape,
A yellow iron oxide pigment whose long axis is 100 to 350 and whose axial ratio is . Iron hydroxide is prepared by adding and mixing an aqueous ferric salt solution into an alkaline aqueous solution at a temperature of 230°C or lower at a temperature of 30°C or lower, and after aging this, hydrothermal treatment is performed at a temperature of 120 to 250°C. 1. A method for producing a yellow iron oxide pigment, which comprises applying the following steps to produce iron oxide hydroxide powder. 3. To prepare iron hydroxide, adjust the concentration of the ferric salt aqueous solution to 0.5.
3. The method according to item 2, characterized in that the reaction is carried out at an aqueous alkali solution concentration of 4 M/l or less. 4. To prepare iron hydroxide, use the formula for ferric salt and alkali necessary for chemical neutralization [either react with a pre-calculated amount so that the alkali is in excess of the liquid, or , After the precipitation reaction is completed, the free alkali concentration in the total ΔkFn is less than ], OM//! 2. The method according to item 2, wherein the 1 h characteristic is obtained. 5. The method according to item 2, wherein after the precipitation reaction process of iron hydroxide, the precipitate is aged with the IU solution for about 1 hour, and then subjected to hydrothermal treatment.