A method of obtaining a red micaceous iron pigment with specified electrokinetic characteristics

 

(57) Abstract:

Use: preparation of paints. The essence of the invention: preparing a suspension of red micaceous iron pigment, add 0.25 to 1.5 wt.% polyphosphate sodium in terms of P2O5in relation to the pigment or solution of sulfuric acid to a pH of 1.7 and 2.1, treatment of the latter is carried out at 90-100°C for 1-2 hours Get the pigments with a negative value of Zeta-potential, do not have isoelectric points in the pH range of 2 13. The degree of fixing of the pigment in the material with the desired electrokinetic characteristics - 80-97%. table 2.

The invention relates to inorganic pigments used for pigmentation of various materials, in particular phosphors red glow. It is known that the pH value of the isoelectric point (IEP) of the pigments depends on the terms of their treatment and can characterize the dispersion of pigments in various binders, as well as rheological and spectroscopic properties of materials. Pigments with acidic or basic properties of well-dispersed in binders with opposite properties, which improves the quality of the coatings.

A known method according to the t modification with inorganic compounds of magnesium, zinc, aluminum, lanthanum, etc. leading to change the pH of isoelectric point above 7 [1]

The disadvantage of this method is that this trick only allows you to shift the pH value of the isoelectric point (IEP) of a pigment in the 6 units in the alkaline region (pH 2.5 to pH 8-11).

The invention allows to synthesize red micaceous iron pigmet without IEE in the area of values 2<pH<13 and Zeta-potential which has a negative value, which allows to increase the degree of fixing of the pigment in the material with the desired electrokinetic characteristics. This pigment to the greatest degree must satisfy the pigmentation of phosphors red glow on the basis of oxysulfide or yttrium oxide, the particles of which do not have IEP in the specified range of pH values, but with Zeta-potential, which is in the positive area.

The aim is achieved in that in the method of obtaining the red micaceous iron pigment with specified electrokinetic characteristics, including the preparation of its suspension and handling its inorganic substance, as the latter use a solution of sodium polyphosphate in an amount of 0.25 to 1.5 wt. in point lead at pH 1.7 to 2.1 and a temperature of 90-100aboutC for 1-2 h

In the prepared suspension of the pigment is iron oxide is injected quantity of sulfuric acid required to create the values of pH, equal to 2.1 and 1.7, and the suspension is incubated at a temperature of 90-100aboutC for 1-2 h, depending on the concentration of the pigment in suspension.

The lower and upper limits of pH values is due to the fact that at pH < 1.7 pigment begins to dissolve, and at pH > 2,1 not achieved the desired effect because it is connected with the dissolution-precipitation of iron (III) at pH 1.5 and pH 2.3, respectively (see, for example, Hornowski I. T. and other Quick reference for chemistry. Kiev: Naukova Dumka, 1974, S. 352).

The lower limit on temperature is due to the fact that at a temperature of less than 90aboutthe technical result is not achieved even for a time exceeding 5 hours, the Upper limit on temperature is due to the boiling point of suspension of the pigment under normal conditions.

Extract the pigment suspension at the same temperature for less than 1 h (pigment concentration of 100 g/DM3) and 2 h (at a concentration of 200 g/DM3also does not give the desired effect, i.e., the pigment has an IEP at pH 3.0.

Increasing time of heat treatment for more than 1 h for Pervov the persons receiving micaceous iron pigment without IEP is the pigment suspension is treated with sodium polyphosphate in an amount of 0.25 to 1.5 wt. in terms of R2ABOUT5with respect to the iron oxide. The lower limit of the concentration of sodium polyphosphate due to the value of the specific surface of the pigment (Sbeats60 m2/cm3for phosphors, and the top no further increase in Zeta-potential, i.e., when the amount of sodium polyphosphate by weight less than 0.25. in terms of R2ABOUT5with respect to the pigment is not sufficient to give the required surface properties (discharge) to the pigment particles, and when the amount of sodium polyphosphate in terms of P2ABOUT5more than 1.5 wt. the surface of the pigment particles already formed and its further increase does not affect the charge of the particles.

The influence of sulfuric acid and sodium polyphosphate on the charge of the pigment particles due to the fact that the anions SO42-and RHO42-are sorbed on the surface of the pigment particles, giving them a negative charge.

P R I m e R 1. In a suspension of red micaceous iron pigment concentration in the pigment 200 g/DM3enter sulfuric acid portions to achieve a pH equal to 2. The suspension is maintained at a temperature of 90-100aboutis the rd pH appropriate IEP and the degree of fixing of the pigment in its treatment of the suspension with a solution of H2SO4.

P R I m e R 10. In the willing suspension of red micaceous iron pigment washed from soluble salts, the concentration of 200 g/DM3with stirring, enter 0.5. polyphosphate sodium in terms of P2ABOUT5with respect to the pigment. Get a stable suspension of pigment, no IEP in the range 2 < pH<13.

Presented in table.1 and 2 data shows that the invention allows to obtain pigments with a negative value of Zeta-potential, do not have isoelectric points in the range 2<pH<13. This allows to increase the degree of fixation of pigments to 80-97% on materials with known electrokinetic characteristics (plastic, paper, chemical fiber, phosphors, and so on).

A method of OBTAINING a RED micaceous iron PIGMENT WITH SPECIFIED ELECTROKINETIC CHARACTERISTICS, including the preparation of its suspension and handling its inorganic substance, is great for the household characteristics, as the inorganic substances used solution of sodium polyphosphate in an amount of 0.25 to 1.5 wt. in terms of P2O5in relation to the pigment or solution of sulfuric acid and the treatment of the latter is carried out at a pH of 1.7 to 2.1 and a temperature of 90 - 100oWith in 1-2 hours

 

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