Anticorrosive pigment

 

(57) Abstract:

The invention relates to the technology for anti-corrosive pigments used in the paint industry. The invention consists in an anti-corrosive pigment, represents the phosphate-chromate calcium at a molar ratio of phosphate and chromate ions in it from 1: 1 to 4:1. Anti-corrosive pigment is designed to reduce toxicity by reducing its solubility in water by partial replacement of chromate ion to phosphate ion without lowering anti-corrosive properties. All the pigments have the property to reduce the corrosion current and shifts the potential of the steel in the area of active corrosion inhibition. table 2.

The invention relates to the technology for anti-corrosive pigments, for example, in the paint industry.

Known anti-corrosive pigment, represents the chromate calcium composition CaCrCO4(Belenky, E. F., Raskin I. C., Chemistry and technology of pigments. L., Chemistry, 1974, S. 21, 22).

However, the pigment has a high toxicity associated with high water solubility of this compound, which limits the scope of his Spolsky object of the invention is to reduce the toxicity of the pigment by reducing its solubility in water without lowering anti-corrosive properties.

The task is achieved anticorrosive pigment, represents the phosphate-chromate calcium at a molar ratio of phosphate and chromate ions in it from 1:1 to 4:1.

Obtaining the pigment is carried out by mixing a concentrated suspension of calcium hydroxide in series with concentrated solutions of chromium trioxide and phosphoric acid at room temperature. A concentrated suspension of the pigment is dried at a temperature of 105-200oC. the resulting yellow product containing water of crystallization, can be used without additional heat treatment or subjected to dehydration at a temperature of 600-650oC obtaining pigment green, the shade of which depends on the composition.

Example 1.

78 g of calcium hydroxide content of the basic substance 86,6% mixed with 75 ml of water. To the resulting suspension under vigorous stirring gradually added 24 ml of a solution of chromium trioxide content of the basic substance 57% (the density of a solution of 1.59 g/cm3), diluted with 30 ml of water. The mixture is stirred for 1 hour and then treated 29 ml of orthophosphoric acid with a basic substance content of 85.5% within 2 hours after administration of the total number of orthophosphoric acid.

The precipitated product composition corresponds to the formula CaCrO4Ca3(PO4)23H2O. After calcination at a temperature of 600-650oC for 2 hours, the pigment loses its water of crystallization.

Example 2.

Analogously to example 1, but are respectively 14 and 35 ml of concentrated solutions of chromic anhydride and phosphoric acid.

The precipitated product composition corresponds to the formula CaCrO42Ca3(PO4)26H2O.

Example 3

Analogously to example 1, but taken respectively 85 g of calcium hydroxide, 8, and 40 ml of concentrated solutions of chromic anhydride and phosphoric acid.

The precipitated product composition corresponds to the formula CaCrO44Ca3(PO4)29H2O.

Example 4

Analogously to example 3, but without calcination.

The properties of the pigments are shown in table 1.

Evaluation of corrosion properties of pigments was carried out potentiostatic method. As corrosive fluids used 3% solution of sodium chloride at a pH of 4.5, established acetic acid. The calculation of the corrosion currents were carried out according to the method (Horlivka, I. A., Indacin E. A., Tocorrosion inhibition was calculated as the ratio of potential to current corrosion. The indicators are shown in table 2.

In the process the corrosive environment under the coating on the metal surface is formed photogrametry film that causes passivation of the surface and providing an additional protective effect in contrast to sample 1.

Thus, these pigments have the property to reduce the corrosion current and shifts the potential of the steel in the area of active corrosion inhibition. The samples in examples 3 and 4 have a solubility in water of less than chromate calcium and tetrachromat zinc, and have a significantly lower content of chromium.

Anti-corrosive pigment-based calcium, characterized in that it is a phosphate-chromate calcium at a molar ratio of phosphate and chromate ions in it from 1 : 1 to 4 : 1.

 

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FIELD: chemical and pulp-and-paper industry.

SUBSTANCE: aqueous suspension of at least one filler or mineral contains natural carbonate, polymeric dispersing agent as stabilizer of suspension viscosity, product of natural carbonate treatment with gaseous CO2, and product of natural carbonate reaction with at least one medium or strong H3O+-donors, has pH more than 7.5 at 200C. As natural carbonate suspension contains calcium carbonate (e.g., marble, calcite, carbonate-containing dolomite, chalk, ore mixtures thereof with talcum, and/or TiO2, MgO, or other minerals inert to H3O+-donors). As H3O+-donors suspension contains H2SO3, HSO

-4
, H3PO4, oxalic acid or mixtures thereof in molar ratio to carbonate of 0.1-2. Used carbon dioxide under pressure of 0.05-5 bar may be added from outside, recycled or obtained by continuous H3O+-donors addition. Treatment with H3O+-donors and gaseous CO2 may be carriedout simultaneously or separately, wherein in the last case temperature and time of respective stages are 5-900C and 1-5 h. Claimed suspension is dried to obtain colorant. Colorant has BET specific surface of 5-200 m2/g according to ISO 9277 and mean grain size measured by sedimentation method of 0.1-50 mum. Colorants are used in compositions, as agent for paper lamination, for paper pulp filling, coloration, and board production. Obtained paper is useful in numeric and ink-jet printing.

EFFECT: paper with decreased mass at constant surface.

33 cl, 1 dwg, 2 tbl, 8 ex

FIELD: paper-and-pulp industry.

SUBSTANCE: invention relates to pigment, which can be used in manufacture of paper with filler, coated paper, and cardboard. Calcium hydroxide and calcium carbonate powders taken in proportion between 1.0:2.2 and 1.0:23.5 are added to vigorously stirred water, after which temperature of mixture is raised to 80-85°C and resulting reaction mixture is kept being stirred for 90-180 min to form dispersion of pigment containing 20-35% solids.

EFFECT: improved quality of pigment at lower cost and extended application area.

3 tbl

FIELD: paper-and-pulp industry.

SUBSTANCE: calcium carbonate product is designed for containing paper and comprises mixture of first and second separate calcium carbonate particles, wherein difference between first and second calcium carbonate particles ranges from about 0.1 μm to 0.2 μm and weight ratio of first to second particles lies between about 50:50 and about 80:20. Pigment is intended for coating paper and made from above-defined product. Method concerns containing paper and comprises preparation of mixed pigment based on calcium carbonate precipitated in the form of aragonite having above-indicated makeup; addition of binder; and deposition of the pigment onto a base paper in the form of binder-containing suspension. Paper is then dried and calendared. Also described are: paper obtained by above method; a method to increase gloss of paper sheet involving operation of including above product into base paper coating suspension; a method to increase gloss of paper involving operation including calcium carbonate product wherein first calcium carbonate particles have average size about 0.4 μm and the second ones about 0.5 μm at their weight ratio 60:40, respectively; a method to increase gloss of paper sheet involving operation of including pigment based on argonite-type calcium carbonate with difference between first and second average particle size values from about 0.1 μm to 0.2 μm and their weight ratio between about 50:50 and about 80:20 into base paper coating suspension.

EFFECT: increased gloss of coated paper sheets.

24 cl, 3 tbl

FIELD: pulp and paper industry; methods of production of the pigment for manufacture of the cardboard and paper.

SUBSTANCE: the invention is pertaining to the method of production of the pigment for manufacture of the cardboard and paper and may be used in pulp and paper industry at production of the filled paper, the coated paper and the cardboard. In the water at intense stirring feed powders of calcium hydrate and calcium carbonate at the ratio of the indicated components accordingly from 1.0:2.2 up to 1.0:12.9. The produced suspension is gradually added with aluminum sulfate at its ratio to the total mass of the calcium hydroxide and calcium carbonate from 1.0:0.85 up to 1.0:4.30. Then the temperature of the mixture is increased up to 8О-85°С and the produced reaction mixture is kept at stirring within 90-180 minutes with formation of the dispersion of the pigment with the share of the dry substances in it equal to 20-35 %. Then the dispersion is dried and grinded into the powder. The powder is dispersed in the water containing the given amount of the dissolved coolant and-or binding - starch or polyvinyl alcohol. The technical result of the invention production of the pigment with the new properties, that allow to expand the field of its application at manufacture of various types of the cardboard and the paper.

EFFECT: the invention ensures production of the pigment with the new properties, expansion of the field of its application at manufacture of various types of the cardboard and the paper.

2 tbl

FIELD: pulp and paper industry; methods of production of the pigment for manufacture of the cardboard and paper.

SUBSTANCE: the invention is pertaining to the method of production of the pigment for manufacture of the cardboard and paper and may be used in pulp and paper industry at production of the filled paper, the coated paper and the cardboard. Calcium hydroxide suspension is treated with aluminum sulfate solution in the aqueous medium at stirring. The treatment is conducted in the aqueous medium containing the binding in the dissolved state. The binding is chosen from the group, which includes starch and polyvinyl alcohol in the amount of 0.5-5.0 mass % from the mass of the absolutely dry pigment, and-or the colorant in the amount of 0.1-0.5 mass % from the mass of the absolutely dry pigment. The technical result of the invention is the improved quality of the pigment and expansion of its field of application.

EFFECT: the invention ensures the improved quality of the pigment and expansion of the field of its application.

2 tbl

FIELD: pulp and paper industry; methods of production of the pigment for manufacture of the cardboard and paper.

SUBSTANCE: the invention is pertaining to the method of production of the pigment for manufacture of the cardboard and paper and may be used in pulp and paper industry at production of the filled paper, the coated paper and the cardboard. Calcium carbonate is treated with aluminum sulfate in the aqueous medium. The treatment is conducted at aluminum sulfate consumption of 25-105 % to the mass of absolutely dry calcium carbonate at the temperature of 80-85°С during 90-180 minutes with production of the suspension containing 25-35 % dry substances in it. At that they use the aqueous medium containing the binding chosen from the group, which includes starch and polyvinyl alcohol in the amount of 0.5-3.0 mass % from the mass of the absolutely dry pigment, and-or the water soluble colorant in the amount of 0.1-0.5 mass % from the mass of the absolutely dry pigment. The suspension is additionally dried and grinded. The technical result of the invention is the improved quality of the pigment as well as expansion of its field of application.

EFFECT: the invention ensures the improved quality of the pigment as well as expansion of its field of application.

2 tbl

FIELD: pulp and paper industry; methods of production of the pigment for manufacture of the cardboard and paper.

SUBSTANCE: the invention is pertaining to the method of production of the pigment for manufacture of the cardboard and paper and may be used in pulp and paper industry at production of the filled paper, the coated paper and the cardboard. Calcium carbonate is treated with aluminum sulfate in the aqueous medium. The treatment is conducted at aluminum sulfate consumption of 25-105 % to the mass of absolutely dry calcium carbonate at the temperature of 80-85°С during 90-180 minutes with production of the suspension containing 25-35 % dry substances in it. The suspension may be additionally dried and to produce the powder. The technical result of the invention is improvement of the pigment quality and expansion of the field of its application.

EFFECT: the invention ensures improvement of the pigment quality and expansion of the field of its application.

2 cl, 2 tbl

FIELD: paint and varnish industry.

SUBSTANCE: anticorrosive pigment comprises , in mass per cents, 3.0-4.7 of calcium chromate and waterless dicalciumphosphate as the balance.

EFFECT: improved anticorrosion capabilities.

1 tbl

FIELD: chemistry.

SUBSTANCE: invention can be used in the painting and coating, rubber and paper industries to obtain barium sulphate from natural barite. The method of obtaining barium sulphate involves treating barite with molten salts with subsequent cooling of the melt, dissolving in water, filtration, washing the product on the filter with water and drying. The melt of salts used is a mixture of sodium and potassium salts with a molar ratio of 1:1. The melt is added to barite of mass of not more than 25% of the mass of the melt of the salts. A stream of dry hydrogen chloride is passed through the mixture of melts at temperature of 700-800°C.

EFFECT: stable production of product with high degree of purity and whiteness.

3 ex

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