CS244782B1 - Core anticorrosive pigments based on calcium, zinc, manganese, ferrous iron and lead oxalates - Google Patents

Abstract

The subject of the solution are core anti-corrosion pigments based on oxalates of calcium, zinc, manganese, divalent iron and lead or their mixtures, applied as a coating in an amount of 1 to 10%, preferably 3 to 6 i, on the surface of inorganic pigments and fillers serving as a carrier substance /titanium dioxide, iron oxide, lithopone, blanc-fixe, silicon dioxide, aluminum silicates, alkaline earth magnesium, calcium and magnesium carbonates/. The subject of the invention is also a method of preparing these pigments, which is characterized in that an aqueous solution of oxalic acid, a metal salt and an alkali hydroxide is added to an aqueous suspension of inorganic pigments and fillers simultaneously with stirring and a temperature of 50 to 70 ° C, at a constant pH in the range of 5 to 8, within 1 to 3 hours. After a 30-minute delay, the treated product is filtered, washed, dried at a temperature of 120 to 140 °C and ground.

Description

The invention relates to core anti-corrosion pigments based on oxalates of Ca*, Zr*, In*, Fe* and Pb* applied as a coating on the surface of inorganic pigments or fillers serving as a carrier substance.

Oxalic acid and its alkaline salts with additives of some heavier metals, for example Fe and Fe, have a similar importance in anti-corrosion protection as zinc phosphate. Oxalation of metals before applying organic coatings has been known for more than 60 years and is still used. The oxalation process is understood as the action of oxalic acid or alkaline salts with the addition of oxalates of heavy metals on the protected metals. In this process, an inhibitory layer is formed, consisting of oxalates of the protected metal and added additives, which, similarly to the phosphating process, protects the metals from atmospheric influences.

Based on the above facts, the development of core anti-corrosion pigments using sparingly soluble oxalates of heavy metals and calcium, precipitated as a coating on various inorganic carriers, was also monitored.

This method of preparing core anti-corrosion pigments based on oxalates is original and has not yet been published in the available patent literature.

* The subject of the invention are core anti-corrosion pigments based on oxalates of Ca ²⁺ , Zn ²⁺ , Mn ²⁺ , Fe ²⁺ and Pb ²⁺ or their mixtures applied as a coating in an amount of 1 to 10. >6, preferably 3 to 6 on the surface of inorganic pigments and fillers, such as titanium dioxide, iron oxide, lithopone, blanc-fixe, silicon dioxide, aluminum silicates, alkaline earth and magnesium silicates, calcium and magnesium carbonates.

The invention also relates to a method for preparing these pigments, which is characterised in that an aqueous solution of oxalic acid, a metal salt and an alkali hydroxide is simultaneously added to an aqueous suspension of inorganic pigments and fillers under stirring at a temperature of 50 to 70 °C, at a constant pH in the range of 5 to 8, within 1 to 3 hours. After a 30-minute delay, the treated product is filtered, washed, dried at a temperature of 120 to 140 °C and ground.

In order to ensure perfect precipitation of oxalates on the surface of the support, it is necessary that the metal salts are added in a 5 to 10% excess. As alkaline hydroxides, ?íaOIi or KOh, gaseous or liquid ammonia are used.

Almost all inorganic pigments and fillers used in the paint and varnish industry with a suitable particle size can be used as carriers for the preparation of the core anti-corrosion pigments according to the invention.

The metal salts to be used for precipitation are added in the form of aqueous solutions, either separately or in a mixture. During precipitation, they are added slowly and uniformly so that insoluble oxalates precipitate on the surface of the carrier. Since the metal salt solutions added to the carrier suspension are strongly acidic, the pH of the suspension is kept constant during precipitation by simultaneous addition of an alkali hydroxide. Any inorganic or organic base which does not adversely affect the precipitated products can be used. All water-soluble salts can be used as metal salts. Chlorides and sulfates are particularly preferred. In the case of iron, FeSO4.TiO is particularly suitable.

The progress achieved by the invention consists in the development of new types of core anti-corrosion pigments from available and cheap raw materials with very good inhibitory properties.

Example 1 g of iron oxide is dissolved in demineralized water to a volume of 500 ml with stirring and at a temperature of 60 °C. A 5% aqueous solution containing 4.92 g (COOH) ₂ .2H ₂ O is added to the suspension at a constant pH of 6 and at the same time a 5% aqueous solution containing 4.6 g CaClg is added over 30 minutes. The constant pH is maintained with a 10% aqueous solution of NaOH. After a 30-minute delay, the treated product is filtered, washed, dried at a temperature of 140 °C and ground.

- 3 Example 2

244,782 g of titanium dioxide are dissolved in demineralized water to a volume of 500 ml, while stirring at a temperature of 60 °C and at a constant pH of 7, a 5% aqueous solution containing 4.11 g of ZnSO4 is added over 1 hour, and a 5% aqueous solution containing 9.84 g of ZnSO4 and 10% aqueous NaOH is added at the same time. After a 30-minute delay, the treated product is filtered, washed, dried at a temperature of 130 °C and ground.

Example 3 g of silicon dioxide is dissolved in demineralized water to a volume of 500 ml, while stirring and at a temperature of 60 °C and at a constant pH of 7, a 5% aqueous solution containing 4.41 g (COOiOg.ČHgO) is added over a period of 30 minutes and at the same time a 5% aqueous solution containing 8.19 g KnS0^.4h ₂ 0 and a 10>b aqueous NaOH solution are added. The treated product is filtered, washed, dried at a temperature of 130 °C and ground.

Example 4 g of kaolin is dissolved in demineralized water to a volume of 500 ml, while stirring at a temperature of 60 °C and at a constant pH of 6, a 5% aqueous solution containing 4.52 g of (COOH^.ZH^O is added over a period of 30 minutes and at the same time a 5% aqueous solution containing 12.94 g of CH^COOÍgPb.JH^O and a 10% aqueous solution of NaOH are added. After a 30-minute delay, the treated product is filtered, washed, dried at a temperature of 130 °G and ground.

Example 5 g of calcium carbonate is dissolved in demineralized water to a volume of 500 ml, while stirring at a temperature of 60 °C and at a constant pH of 7, a 5% aqueous solution containing 4.9 g of (C00H) ₂ .2H ₂ 0 is added over a period of 30 minutes and at the same time a 5% aqueous solution containing 4.6 g of CaCl ₂ and a 10% aqueous solution of NaOH are added. After a 30-minute delay, the treated product is filtered, washed, dried at a temperature of 130 °C and ground.

AND

Example 6

244,782 g of talc are dissolved in demineralized water to a volume of 500 ml, while stirring at a temperature of 60 °C and at a constant pH of 6, a 10% aqueous solution containing 4.38 g of ÍCOOlOg.ŽHg ⁰ is added over a period of 30 minutes and at the same time a 10% aqueous solution containing 10.15 g of PeSO^.THgO weakly acidified tgSQ^ is added. A constant pH of 6 is maintained by adding 10.% aqueous NaOH solution. After precipitation, the pH of the suspension is adjusted to 7. After a 30-minute delay, the treated product is filtered, washed, dried at a temperature of 120 °C and ground.

Example 7

The procedure is the same as in Example 1, except that lithopone is used as the carrier substance.

Example 8

The procedure is the same as in example 2, except that 94 g of titanium dioxide is used and 5% aqueous solution containing 4.31 g of (C00H) ₂ .2H ₂ 0 and a 5% aqueous solution containing 5.62 g of ZnS0 ₄ .7H ₂ 0, 1.73 g of CaCl ₂ and 1.56 g of 1&nSO^^O are added. The further procedure is identical to example 2.

- 5,244,782

Corrosion tests were performed in an aqueous extract of a paint film with pentaerythritol alkyd binder CHSP-165, modified with 65% linseed oil with a volume concentration of 30% OKP for a period of 10 days.

The test results of the core anti-corrosion pigments are shown in the table in comparison with pure alkyd binder, water and zinc phosphate.

As can be seen from the table, core anti-corrosion pigments based on oxalates have very good inhibitory properties.

Table.

Example Pigment Corrosive Inhibitory • decline /Um/year efficiency % 1 ferric oxide + 5% oxalan Ca^ ⁺ 0.84 97.35 2 titanium dioxide + 5% oxalan Zn^ ⁺ 1.19 96.94 3 2+ silica + 5 # oxalate Wn 1.20 96.92 4 2+ kaolin + 5% Pb oxalate 1.06 97.28 5 calcium carbonate + 5% oxalate Ca* 0.59 98.50 6 2+ talc + 5% Fe oxalate 1.09 97.20 7 2+ lithopone + 5 7o oxalate Ca 0.94 97.60 8 2+ titanium dioxide + 3% Zn oxalan + 2% oxalan Ga^ ⁺ + 1% oxala- ΊΤ 2 + nu Lin 0.70 yS,20 zinc phosphate 0.84 97.35 - alkyd CHSP - 165 34.20 11.90 - water 38.80 -

P S B D Μ 8 T OF THE INVENTION

Claims (3)

Jád »Core anticorrosive pigments based on oxalanes of calcium, zinc, manganese, divalent iron and lead, characterized in that they consist of a core such as titanium dioxide, iron oxide, barium sulphate, lithopone, silicon dioxide, aluminum silicates, alkaline earths, magnesium and calcium and magnesium carbonates, and from the coating of calcium oxalate, zinc, manganese, ferric iron and lead alone or in a mixture in an amount of 1 to 10, preferably 3 to 6, by weight of the anticorrosive pigment as a whole. 2. A process for the preparation of the core anticorrosive pigments according to claim 1, characterized in that an aqueous suspension of inorganic pigments or fillers at a concentration of 100 to 300 g in 1 is added to the aqueous suspension. water added with stirring, at a temperature of 50 to 70 ° C at a constant pH of 5 to 8, An aqueous solution of oxalic acid and an aqueous solution of calcium or zinc, manganese, ferrous, lead salts, or a mixture thereof, and an aqueous solution of 5 to 10/6 alkali hydroxide, after 30 minutes delay, the treated product is filtered, washed, dried at 120 to X40 ° C and ground.