LV12958B - Inhibitors of ferrous metal corrosion - Google Patents

Abstract

This invention pertains to the field of inhibition of ferrous metal corrosion. The mentioned invention has enlarge ferrous metal protection field and could be applied to ethylene glycol-water systems and to alkyd-coatings. The intention is achieved by adding sodium sorbitol-borate Na[C6H14BO8]. The compound sodium sorbitol-borate (40 % solution in water) could be synthesised from D-sorbitol, borax and sodium hydroxide.

Description

Ferrous metal corrosion inhibitor

The present invention relates to ferrous metal corrosion inhibitors. Borogluconate-based corrosion inhibitors of ferrous metals are known. For example, sodium-calcium borogluconate, trisubstituted sodium borogluconate and compositions based thereon [1-3], These inhibitors work only in neutral aqueous solutions because they are too insoluble in ethylene glycol and organic solvents which limit the scope of these inhibitors. For example, the solubility of trisubstituted sodium borogluconate in ethylene glycol-water 1: 1 at 20 ° C is less than 0.08 g / l, in ethylene glycol-water mixture 1: 2 - 0.28 g / l, but the protective concentration ϊτ is not less than 0.5 g / l. On the other hand, there is a known inhibitory composition NC-2 - a mixture of sodium glyceroborate and borac [4], which is highly soluble in ethylene glycol-water and protects steel, brass, copper and cast iron. The disadvantage of this composition is the relatively weak effect. Therefore, the object of our invention is to provide an effective more versatile ferrous metal corrosion inhibitor, which works not only in aqueous solution but also in ethylene glycol-water mixtures and alkyd paints and can serve as a corrosion inhibiting additive for ferrous metals in ethylene glycol-water based also for corrosion inhibiting and structuring additives in alkyd coatings.

These goals are achieved with a new anti-corrosion additive, sodium sorbitol borate Na [C6Hi4BOg] and its concentrated aqueous solution.

The target substance is obtained from D-sorbitol, borac and sodium hydroxide by reaction (1).

4C6Hi ₄ O ₆ + Na ₂ B ₄ O ₇ .10H ₂ O + 2NaOH - * 4NA [C ₆ H _l4 BO _g] + 11H ₂ O (1) or D-sorbitol and sodium Monoborate by reaction (2)

C ₆ H ₁₄ O ₆ + NaB (OH) ₄ .2H ₂ O - + Na [C ₆ H ₁₄ BO ₈ ] + 4H ₂ O (2)

Any other sodium tetraborate hydrate and an appropriate amount of water may be used instead of borac. The synthesis results in a colorless, transparent syrupy liquid, which is miscible with water and ethylene glycol.

The resulting syrup can give a glassy sorbitol borate NaCeHi + BOg], which is easily pulverized to a powder. Sodium sorbitolborate is a white powder which is freely soluble

In water, slightly soluble in ethylene glycol up to glass formation, but as shown in Table 1, slightly soluble in organic solvents.

The individuality and chemical formula of sodium D-sorbitolborate have been demonstrated by chemical analysis, thermoanalytical curves (Fig.1) and infrared spectra (Fig.2).

The thermoanalytical curves and infrared spectra are individual, specific to D40 sorbitolborate only and suggest that D-sorbitolborate Na [C ₆ Hi40gB] is an individual chemical compound.

Sodium sorbitol borate syrup mixes easily with colors. The resulting formulation is unaffected by mold fungi. Both the anhydrous preparation and the 40-concentrate in water effectively protect the steel from corrosion in neutral aqueous solutions over a wide temperature range as shown in Table 2, which shows the corrosion rate in g / m ² .h and the percentage effectiveness of the inhibitor in distilled water at 70 ° C. (inhibitor efficacy

98.2-99.3%). After measuring the polarization resistance at 20 ° C, the efficacy of the target substance inhibitor at concentrations of 1 and 2 g / l is 98.3%.

The target product can serve as an effective corrosion inhibitor of ferrous metals in diesel cooling systems and heat carriers.

Table 3 shows the corrosion rate of 08IIC of low alloy steel in g / m ² .h and the effectiveness of the inhibitor at 70 ° C in ethylene glycol - aqueous media in a 1: 1 and 1: 2 by volume ratio compared to prototype NC-2 (Latvian Patent No. 10101; .95), as can be seen from the data in Table 3, the target substance is much more effective than the prototype as a corrosion inhibitor of ferrous metals and can thus serve as an anti-corrosion additive based on ethylene glycol water. As shown in Table 3, D-sorbitolborate, an object of the present invention, effectively inhibits the corrosion of steel not only in ethylene glycol-water mixtures, but also in ethylene glycol-artesian water mixtures. This can facilitate the preparation of antifreeze on the road and in other extreme cases. Table 4 shows the effect of the target substance on the coating of alkyd paint PF-115 on CT 3 steel. As shown in Table 4, the target substance additive increases the coating resistance by 46% at 50% overnight for 3% sodium chloride solution. Respectively, the metal's corrosion protection under the paint coating is increased. The following are examples of a better understanding of the invention.

-3Example 1.

129 cm ^{3 of} distilled water is heated to 80 ° C and dissolved in 74.1 g of D-sorbitol (Neosorb P20 / 60, Roquette, 98% basic material), then add 38.1 g of borax and continue stirring and heating until all borax dissolves . Then carefully add small portions of 8 g of sodium hydroxide. Cool the reaction mixture. 249 g of Na-sorbitol borate concentrate are obtained, with a starting material content of 39.72%. The concentrate has a density at 18 ° C of 1.234 g / cm ³ , a boron content of 1.692% and a theoretical content of 1.73%. In order to isolate the substance in the solid phase, the concentrate is dried at room temperature in a thin layer in a foil bath to constant weight. Colorless glass is ground into a powder. Target substance identified by chemical analysis, thermoanalytical curves (Derivatograph Q-1500) and infrared spectra (UR-20)

Found:% C-30.27; H, 5.38; B-4.26; Na-9.70.

Calculated by the formula Na [C6Hi ₄ BOgj: C-29.94%; H, 5.70%; B, 4.36%; Na9.27%.

As shown by the thermogravimetric curve (FIG. 1), the weight loss at 700 ° C is 73.48%, the excess after heating identified as sodium monoborate NaBO ₂ is 26.52%. Calculated from equation (3), the weight loss and NaBO ₂ are 73.15% and 26.85%, respectively. The infrared spectrum of the substance is shown in FIG. 2. It is specific to the substance NafCeH ^ Og] and is indicative of its individuality.

NaC & HuBOg] t °, O ₂ -> NaBO ₂ + 6CO ₂ + 7H ₂ O (3)

Example 2.

Solutions were prepared from sodium sorbitol borate concentrate synthesized according to the method of Example 1 in distilled water at concentrations of 1 and 2 g / l, based on anhydrous sodium sorbitol borate NafCeHuBOg]. ° C and 70 ° C by gravimetric method and polarization resistance method. The results are shown in Table 2.

Inhibitor efficacy E,% calculated using the formula,

E-Kbez inhib. “Kar inhjb. / Kfeez inhib. x 100% where K without inhib- corrosion rate in g / m ² .h without inhibitor additive, K with inhib. corrosion rate, g / m ² .h with inhibitor.

-4115 Example 3.

Sodium sorbitol borate concentrate, prepared according to the method of Example 1, was dissolved in ethylene glycol-water mixtures at a ratio of 1: 1 and 1: 2 to obtain inhibitor concentrations of 1, 2 and 3 g / l, based on anhydrous NafCeH 2 Og],

120 In addition, ethylene glycol-water mixtures were prepared with distilled and artesian water.

The solutions were used to determine the corrosion rate and inhibitory efficiency of 08IIC mild steel in static conditions at 70 ° C and 240 hours

125 (gravimetric method). The results are shown in Table 3.

Example 4.

The 40% concentrate of the target substance in water was mixed with an alkyd paint PF-115 (white, glossy) to give a 1% dye inhibitor based on NafCl3HuBOs].

130 CT 3 - 10x15 cm steel samples painted with this color.

Double layer coating thickness 80 mkm, drying temperature 20-25 ° C, curing time 5-8 hours. The potential of the electrode was measured with the potentiostat P-5827M using a silver chloride electrode as a reference electrode. Same samples

135 were prepared by staining them with PF-115 dye without the addition of the target substance. The samples were exposed for 50 days in 3% NaCl solution and compared by calculating a so-called protective margin. R% in the formula

R = [(200+ Eso) / (200+ Eso)] χ 100.

The results are shown in Table 4

Table 1

Solubility of the inhibitor sorbitol borate, 20 ° C

¹ ----- 'V ................. ¹ Solvent Solubility in Na [C6Hi4BOg],% by weight Water unlimited to glass making Ethylene glycol unlimited White Spirit 0.088 Ethanol 0.030 Solvent 0.204 Acetone 0.040 Isoamyl alcohol 0.156 Benzene 0.128

Table 2

The effect of sodium sorbitolborate NafCiHtuBOsj and its 40% concentrate in water, the subject of the present invention, on the corrosion rate of low-alloy steel 08 IIC in distilled water at 70 ° C, gravimetric method, holding time - 240 hours.

Inhibitor concentration in g / l Na-sorbitol borate Na-borogluconate prototype Dry substance 40% - concentrate Corrosion rate in g / m ² .h Inhibitor effect, % Corrosion rate in g / m ² .h. Inhibitor effect, % 0 0 0.3309 - 0.33048 - 1 2.5 0.0058 98.2 0.0076 97.7 2 5 0.0022 99.3 0.0031 99.1 * Made with micro biology technologies.

Table 3

Effect of Inhibitor NafCeHnBOs] and its 40% Concentrate on 80: 1C Corrosion Rate of Low Alloy Steel in Ethyl Glycol-Water 1: 1 and 1: 2 (V / V) at 70 ° C (Gravimetric Method, 10 Days)

The environment Ethylene glycol: water 1: 2 Distilled water Inhibitor efficiency, o 98.7 98.2 98.5 OO oo Corrosion rate, g / m ² .h. Γ 0.20328 0.00273 0.00365 0.00297 0.022 1s: water 1: 1 Artesian water Inhibitor efficiency, % 1 95.5 r-T σ \ 1 Corrosion rate, g / m ² .h. 0.09667 0.00437 0.00297 0.00234 1 Epilogue! Distilled water Inhibitor efficiency, % » 97.1 97.1 97.3 1 Corrosion rate, g / m ² .h. 1 0.15078 0.00437 0.00432 0.00441 Inhibitor concentration, g / l CZ) -4— »ι — i ICO oc t— O c CQ ω o _ = ^c hS O Z ro- cn ITl Prototype NC-2 * tr> Γ- 00 O 'S CQ ω 2 '> X ro Ό CZ) ο 3 i — _j CO cO z o - CN Γ * Ί

Z cO »-> c <L> a CL CZ) Λ • - cS

CCN i

o z

Λ '5' n o

CL p

o □

u.

o

- «- * ·

LS c

*

Table 4

Effect of Sodium Sorbitolborate Additive on the Protective Capability of PF-115 (White, Gloss) Coatings (Additive Concentration 1%)

Exposure time, 24 hours System electrode potential, mv Without additive NafCeH ^ Og] additive R% 1 80 150 100 5 15th 148 99 10th 7th 139 97 15th -23 127 93 20th -34 119 91 25th -60 110 89 30th -70 99 85 35 -90 89 83 40 -115 67 76 45 -130 -15 fifty three 50 -150 -39 46

R,% * is the protection reserve after 50 days exposure to 3% NaCl solution.

? ig.I. Thermogravimetric curve for sodium sorbitol borate

ν? '

Ε-ι

Literature

1. KaaeK B.M., IIlBapu E.M., EayMaHnc Α.Χ., Tejib ^ eHCKaa Π.Η., JīnenHHb Λ.Κ., ΗβΒΗΗΤ> ιη Α.Φ., H3b. AH JlaTB. CCP, Cep. Xhm. 1970. 2. c. 238-239

2. KaaeK B.M., IIlBapu E.M., TejibxeHCKaa Π. H. h up. ΑΒτοροκοε CBHflerejibCTBO CCCP N ° 1389275 ot 31.hk) jih 1986 Cnocoú nojiyneHH5i ΗΗΓηΰητοροΒ Kopo3nn nepHbix MeTajuioe

3. J. Schwarz, H. Krasts, A. Putnina, B. Berge, I. Vitola. Latvian Patent LV-12091 of 20.12.1998 A method for obtaining ferrous metal corrosion inhibitors.

4. ΠγτΗΗΗΈ. JI. $ L, Eepre E.A., IIlBapu E.M., KpacT Χ.Ε., Αβτοροκοε οΒΗΑετβΛΈΟΤΒΟ CCCP 1729138 ot 19.hk) ha 1990 r. Cnocoū nHraūnpoBaHHA κορρο3ΗΗ CTajin b BOAHbix cpeuax

5. Schwarz J., Kalve I., Vaitquayvičene Μ. Z., Leonovich E., Latvian Patent LV-10101 dated 20.04.1995. Inhibitor composition and method of obtaining it.

Claims (5)

Formula of the Invention Ferrous metal corrosion inhibitor, characterized in that it contains sodium sorbitolborate NafCeH 2 Og] or a concentrated aqueous solution thereof for the purpose of expanding its scope. 2. The ferrous metal corrosion inhibitor according to claim 1, characterized in that it is prepared as a Na- (C6Hi4BOg) 39-40% concentrate in water. Use of the ferrous metal corrosion inhibitor according to claims 1, 2, characterized in that, in order to protect the ferrous metal structures from corrosion, it is applied to the neutral water systems in which the said structures operate, 10 concentrations of not less than 1 g / l on the anhydrous basis Na [C6Hi4BOg]. Use of a ferrous metal corrosion inhibitor according to claims 1, 2, characterized in that it is added to antifreeze and heat carriers based on ethylene glycol at a concentration of not less than 1 g / l based on the anhydrous substance NatCgHuBOg] Use of a ferrous metal corrosion inhibitor according to claims 1, 2, characterized in that, in order to protect the metal surface from corrosion under the paint coating, NafCeHuBOg] is added to the alkyd paints in the form of anhydrous substance or a concentrate of not less than 1% by weight or 1% by weight relative to the anhydrous Na [C ₆ H ₁₄ BOg].