How Are Iron Oxide Pigments of Keyue Chemicals Manufacturered?

 

 

 

Iron oxide production process mainly has three ways: wet process, dry process and aniline process.

Keyue Chemicals has developed iron scrap and air oxidation and crystal seed method, and it is one kind of wet process, which can produce iron oxide red and yellow. Dry process is the direct calcination of ferrous sulfate, and iron oxide can be obtained. The aniline process(nanely laux process) is the exclusive use of German company Lanxess, which is a method of using nitrobenzene to be deoxidized with iron powder to produce aniline and byproduct iron oxide.

The production of iron oxide in China is mainly based on wet process, and the production method is nitric acid method, sulfuric acid method and mixed acid method (add both sulfuric acid and nitric acid).

 

I.                      Iron Oxide Red                                                                               

 

Iron oxide red is a kind of red powder, the particle is in spherical structure, and the molecular formula is Fe2O3.

 

 

 

 

 

 

 

 

Due to the different ways of manufacturing, resulting in particle size and shape are also different, making the shades of iron oxide red change from red yellow to red purple, and can choose different shades according to different requirements. Below table shows the relationship between iron oxide particle size and shades, tinting strength, covering power, specific surface area and oil absorption.

 

 

 

Basic properties and performance of iron oxide red

 

       1.The covering power of iron oxide red is very high, only the covering power of carbon black can exceed it, other inorganic pigments are incomparable, which is less than 7g/m2.

       2. Tinting strength of iron oxide red is very strong. The tinting strength of light iron oxide red is better than that of dark iron oxide red with the same production process. So if the color shades are different, the tinting strength can not be compared.

       3. The oil absorption of iron oxide red is very different because of different production process, which is influenced by particle surface condition as well as particle size and shape.

       4. Chemical resistance: Iron oxide red is not soluble in alkali and dilute acid, only in the case of heating can be dissolved in concentrated acid.

       5. Solvent resistance: Iron oxide red is not soluble in organic solvents, water and organic adhesives.

       6. Heat resistance: the heat resistance of iron oxide red can be attained up to 1200 degrees celsius.

       7. Light resistance: iron oxide red is an inert pigment, and is one of the most stable iron oxide pigments. It is very stable in the effect of light, and can absorb the ultraviolet part strongly , so it can protect the color from UV damage.

       8. Weathering resistance: It keeps stable in the effect of water and atmosphere, so that it has the advantage of not being eroded by the weather.

       9. Anti rust: Iron oxide red can play a role in shielding to the goods covered, and its anti rust mechanism is a physical role.

 

 

II.                      Iron Oxide Yellow                                                            

 

 

Iron oxide yellow is a kind of yellow powder, the particle is in acicular structure, and the molecular formula is Fe2O3·H2O  

 

                                              

Iron oxide yellow, also known as hydroxyl iron, is relatively stable alkaline oxides. Its color is with bright and pure yellow ochre, and from lemon to a series of orange shades.

Have a good pigment characteristics, for instance the tinting strength and covering power are both very high. Its tinting strength is almost similar as lead chrome yellow and the covering power is less than 15g/m2, and light resistance is up to 6 ~ 7 grade.

Do not dissolve in alkali, slightly soluble in dilute acid, can be completely dissolved in concentrated acid. The heat stability is not good, when heated up to 150 to 200 degrees Celsius, it starts to dehydrate, when the temperature rises to 270 ~ 300 degrees Celsius dehydrates rapidly and becomes iron oxide red (Fe2O3).

 

 

III.                      Iron oxide black                               

 

Iron oxide is a kind of Black powder, the particle is in spherical structure, and molecular formula is Fe₃O₄(FeO·Fe₂O₃)

 

 

 

Iron oxide black has a saturated blue ink shade, relative density is 4.73 g/cm3, and covering power and tinting strength are very high.

Iron oxide black is very stable in the effect of light and atmosphere, not soluble in alkali, slightly soluble in dilute acid, completely dissolved in concentrated acid.

The heat resistance of iron oxide black is poor, at higher temperatures, it is easy to be oxidized and become red iron oxide. Under normal circumstances, after 200 degrees calcination iron oxide black can be converted to γ-Fe2O3, and in 300 degrees or more converted into α-Fe2O3, which also has a strong magnetic, can be attracted by the magnet.

 

 

IV.                      Iron oxide brown   

  

The largest production of inorganic brown pigment is iron oxide brown. Iron oxide brown can be produced in a direct precipitation oxidation method . However, iron oxide brown is usually produced with the blending of iron oxide yellow, iron oxide red and iron oxide black, so the chemical formula of iron oxide brown is usually showed as (FeO)x﹒(Fe2O3)y﹒(H2O)z .

The oil absorption is between 26%-28%, relative density is 4.70 g/cm3, and has good tinting strength, light resistance and weathering resistance. Because contain iron oxide yellow, heat resistance is not good.

 

Production process is mainly on the basis of blending, color pigments are blended evenly according to the proportion by color matching machine, and adjust the color difference according to the chroma of standard sample. Some varieties are also allowed to add 5% or less carbon black to improve the tinting strength.

 

V.                      Iron oxide orange

Iron oxide orange is usually produced by blending of iron oxide yellow and iron oxide red.

 

 

VI.                      Compound ferric green

 

Compound ferric green is a kind of compound pigment, which is produced by high speed compound of iron oxide yellow and phthalocyanine blue. It is usually not light resistant because of the phthalo blue is not light resistant, soi it is inevitable that it fades with time gradually. Keyue Chemicals has developed the high perfoamance grade of compound ferric green through new technology that has the property of light resistance and keep a stable bright color in the outdoor circumstances.

 

VII.                      Compound  blue

 

Compound blue is also a kind of compound pigment, which is produced by  phthalocyanine blue. Keyue Chemicals has developed the high perfoamance grade of compound ferric blue through new technology that has the property of light resistance and keep a stable bright color in the outdoor circumstances.