PL150742B1 - Preparation for use in a process of etching steel surfaces with hydrochloric acid - Google Patents

Description

PATENT DESCRIPTION

150 742

REPUBLIC

POLAND

OFFICE

PATENT

RP

Additional patent to patent no. Applied for: 86 10 01 / P. 261690 /

Precedence of Ur / Paiemian f »,. U» «ij LtitfWtj

Int. Cl. ⁵ C09K 13/06 C23G 1/06

Application announced: 87 06 01

Patent description published: 1990 11 30

Creators of the invention: Hanna Kryszczyńska, Leopold Mierzejewski, Sylwia Włodarczyk, Marla Kołakowska, Ben and Gna Szeptycka, Ewa Radomska,

Antonina Kozłowska

Authorized by the patent: Institute of Precision Mechanics, Warsaw / Poland /

STEEL SURFACE ETCHER IN HYDROCHLORIC ACID

The subject of the invention is an agent for etching steel surfaces in hydrochloric acid.

The agent is used to activate acid etching of steel in aqueous solutions of regenerated hydrochloric acid by the Ruthner method or to inhibit acid etching of steel in aqueous solutions of hydrochloric acid used in the removal of scale or rust. This method can be carried out as a separate process for industrial cleaning of steel surfaces, in particular wires, sheets, or as one of the unit processes in multi-step surface preparation and coating technologies, such as conversion, organic or metal coatings.

Hydrochloric acid regenerated by the Ruthner method, despite the content of 18-21% of hydrogen chloride, has an effective digestion time much shorter compared to technical hydrochloric acid. Using the same etching parameters of steel samples in both acids with the same HCl concentration, e.g. 18%, the etching of the sample in hydrochloric acid regenerated by the Ruthner method is nearly ten times weaker.

In the process of etching steel surfaces in hydrochloric acid regenerated by the Ruthner method, the use of activating additives is not known, which means that the working time of hydrochloric acid after regeneration is short and the regeneration cycles of this acid are very frequent.

A hydrochloric acid etching inhibitor containing alkynols, ammonium chloride and aliphatic aldehyde is known from the Polish Patent Specification No. 140 308. Adding this inhibitor to hydrochloric acid after Ruthner regeneration extends the lifetime of the acid and makes the regeneration cycles of this acid less frequent.

The aim of the invention is to develop a preparation specially adapted to hydrochloric acid, which after digestion is regenerated by the Ruthner method and which, when introduced into the regeneration of the acid, will significantly extend the working time of this acid than the known inhibitor.

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The aim of the invention is also to develop a preparation which is a digestion activator in hydrochloric acid regenerated by the Ruthner method, which extends the working time of regenerated hydrochloric acid and at the same time will be an effective digestion inhibitor in non-regenerated hydrochloric acid.

After etching, the substrate can also be used to apply protective coatings. Within the scope of the invention, the amounts of the formulation ingredients to be added to the etching solution of known basic composition were determined. The formulation is most suitably prepared by dissolving the ammonium salts in water ₇ and then adding the alkynols or aqueous alkynols to this solution. An etching agent for steel surfaces in hydrochloric acid, which is an aqueous solution containing an ammonium salt as activating compound, and As an alkynyl inhibiting compound of general formula 3, in which R is H or C 11 -OH or CH 2 -O-CH 3 -OH or a group of the general formula 4 _f and R 1 is CH ₂ or CHg-O-CH lub or CHg-O ^GHg-CH-Cl, according to the subject matter of the invention it is characterized in that the activating compound comprises a salt of the formula 1 and / or 2 wherein R is H or ^ _n H _2n _ ,, and n is a natural number from 1 to 4 and X is a sulfate anion or tiocy janianowy, while the amount of ammonium salt is 1 to 30 mmol per 1 liter of the pickling solution with the alkynol. 2 to 40 millimoles per liter of pickling solution.

To obtain the preparation, measured or weighed amounts of activating compounds being ammonium salts of the formulas 1 and 2 and inhibiting compounds being alkynols of the formula 3 are added and mixed together, then made up to a specific volume with water, heated at 70 ° C 1 finally made up with water to the volume specified before annealing. Addition and mixing is carried out such that the ammonium salts are dissolved in water and the alkyneols or aqueous alkynols are introduced into the aqueous solution of the ammonium salts, followed by the usual procedure.

The formulation according to the invention is shown in an embodiment.

Example. 50 millimoles of ammonium thiocyanate are dissolved in 100 ml of water. 40 millimoles of propargyl alcohol are added and then made up to 1 liter with water. It is heated for about 4 hours at 70 ° C. After heating up, the water loss is replenished to a volume of 1 liter. 1 liter of a formulation is obtained which is an aqueous solution containing 50 millimoles of ammonium thiocyanate and 40 millimoles of propargyl alcohol per liter.

The effectiveness of the activating action of the Ruthner-regenerated hydrochloric acid etching preparation was assessed on the basis of the comparison of the steel etching speed in Ruthner-regenerated hydrochloric acid without the addition of the activating-inhibiting preparation and with the addition of this preparation. The etching rate of steel in acid, expressed in g / m ^ h, was calculated according to the formula:

U _ m ♦ 60. »^ 10000 y _g ^ _m 2. _h y where:

m - loss in mass of the etched sample in an acid solution, in grams, o s - area of the etched sample in m, t - sample etching time in hours.

Cold-rolled steel samples / body sheet / with a carbon content of 0.06 p were used for the tests

up to 0.08% and an area of 70 cm. Prior to testing, the samples were degreased in acetone, sanded with 320 grit sandpaper, degreased again in acetone, dried and weighed. Hydrochloric acid regenerated by the Ruthner method was used, with HCl content of 18% by weight, to which an activating-inhibiting preparation was added in the amount of 5 ml / dm \ The process was carried out at 20 ° C with an etching time of 45 minutes. The etching rate of steel in hydrochloric acid was tested for hydrochloric acid immediately after regeneration and for used hydrochloric acid. The hydrochloric acid was run for 8, 12, and 24 hours.

The steel etching rates were as follows. Hydrochloric acid regenerated by the Ruthner method without addition

U, / g / m ^z .h / after regeneration 21.6 after 24 hours of work 14.8

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Hydrochloric acid regenerated by the Ruthner method with the addition of 5 ml / dm3 of an activating-inhibiting preparation

Π- after regeneration 19.6 after 8 hours of work 21.1 after 12 hours of work 25.6 after 16 hours of work 25.8 after 24 hours of work 24.2

The above data show that the addition of an activating-inhibiting preparation to hydrochloric acid after regeneration slightly inhibits the digestion rate / by 2 g / m ² . h /, while during the processing of the etching bath, the preparation activating action begins and after 24 b the speed o

digestion in hydrochloric acid with the addition of an activating-inhibiting preparation is higher by 9-4 g / m * h than the rate of digestion in hydrochloric acid without preparation. Hydrochloric acid without the preparation can be regenerated after this period of work. Hydrochloric acid with the addition of an activating-inhibiting preparation achieves such a low digestion speed only after 40 hours of work, so the working time of hydrochloric acid regenerated by the Ruthner method is 1.7 times longer thanks to the use of the activating-inhibiting preparation.

The inhibitory effect of the stall etching preparation in hydrochloric acid was assessed on the basis of the ability to inhibit the acid reaction with the Hr steel. The measurement was carried out on steel plates and with the etching parameters as in the etching speed tests. Technical hydrochloric acid with a concentration of 16% by weight was used, to which an activating-inhibiting preparation was added in the amount of 5 ml / dm ⁵ The ability to inhibit the reaction of acid with steel H _{r was} calculated using the weight method according to the formula: m »- m-η

H - -S. ₁₀ 0 /% /, rm _A where:

m _A - weight loss of the etched sample in solution A / without inhibitor / in grams, mn - weight loss of the etched sample in solution B / with inhibitor / in grams, fi

An inhibitory capacity of H _r was obtained of 85 3%.

Claims (1)

Patent claim An etching agent for steel surfaces in hydrochloric acid, being an aqueous solution containing an ammonium salt as activating compound and an alkynyl inhibiting compound of general formula 3, in which R is H or CHg-OH or CH ₂ -O-CH ₂ -OH or represents a group of general formula 4 and R ₁ is CH ₂ or CH ₂ -O-CH ₂ or CK ₂ -O-CH ₂ -CH-C1, characterized in that the activating compound is a salt of formula 1 and / or 2, wherein R is H or C _n H _2n-1 , while n is a natural number from 1-4 and I "stands for sulphate or thiocyanate anion, while the amount of ammonium salt is from 1 to 30 millimoles per 1 liter of etching solution and alkynyl from 2 to 40 millimoles per liter of pickling solution. 150 742 ν * Μχ 'Formula 4 Ν ’(ΚΙ, XIΗ X formula 2 R-C = C-R-OH formula 3 n-o-cti-CHfa 11 OH formula 4 Department of Publishing of the UP RP. Circulation 100 copies Price 1500 PLN