SU937539A1 - Composition for electrochemical deposition of polymeric films onto silver surface - Google Patents

Description

used for food contact products due to the toxicity of beryllium compounds.

The closest in technical essence to the present invention is a composition for the electrochemical deposition of polymer strips on the surface of silver, containing polyvinyl alcohol, boric acid and water.

From the composition containing weight. %:

Polyvinyl alcohol 3-7

Borna acid 5 - 1.5 (in

polymer equivalent)

WaterEverything

at a cathode current density of 1.5 mA / cm, a coating of PVA is formed. After washing, a clear coating is obtained with good adhesion to the substrate. Polyvinyl alcohol is a non-toxic polymer and is widely used in medicine 3.

However, the known composition does not allow to obtain a coating possessing anti hydrogen-sulfur properties and preventing the formation of silver sulfides.

The purpose of the invention is to ensure the durability of the silver surface against hydrogen sulfide corrosion.

This goal is achieved in that the composition containing polyvinyl alcohol, boric acid and water additionally contains 2,3-dihydro-2-methyl-1, 4 naphthoquinone 2 sodium sulfonate (vikasol) in the following ratio of components, wt. %

Polyvinyl alcohol 5.0-10.0 Boron acid 0, iZ5-0.5 Vikasol0.1-0.3

WaterEverything

Vikasol, having the structural formula

CH SOfNa HgO

non-toxic compound and is a synthetic analogue of vitamin K.

By cathodic polarization, a water-insoluble PVA coating is obtained on the surface of the product, containing in its structure vikasol, which oxidizes hydrogen sulfide and sulfur compounds and prevents the formation of silver sulfides. The resulting coating swells in hot water and is easily removed from the surface of the product.

The advantage of the proposed composition is that it allows to obtain on the surface a product / coating having counter-sulfur properties, which prevents the formation of silver sulphides.

The introduction of vicasol makes it possible to prolong its action by 4–5 times.

Example. The product is degreased by known methods and washed with water and immersed in a bath with an aqueous J solution of the following composition, wt.% T Polyvinyl alcohol 10.0.1. Boric acid 0,5 Vikasol0,5

Water 89.0 4.

Q Cathode current density 3-5 yA / cm, Temperature 20-25 s. Duration of the process 5 - 20 s.

The thickness of the coating depends on the duration of the process and the current density and is in the range of 0.05 0/3 mm. The content of Vicasol in the coating is determined by its thickness and is 0.15-0.20 weight. %

Example2. The product is degreased by known methods, washed with water and immersed in a bath with an aqueous solution of the following composition, wt. %:.

5 Polyvinyl alcohol 7.0. Borna acid 0.35 Vikasol0,2

Water 92.45

The cathode current density is 0.3 0 0.5 A / dm. Temperature 20-25 s. . The duration of the process 5 - 20 s. The thickness of the coating depends on the duration of the process and the current density and is in the range of 0.04 5 0.2 mm.

The content of Vicasol in the coating is determined by its thickness and is 0.10. - 0.15 weight. %

l Example 3. The product is degreased by known methods, washed with IDA and immersed in a bath with an aqueous solution of the following composition,, weight. %:

Polyvinyl alcohol 5.0 Bornic acid - 0.25. Vikasol0,1

Water94.65

Cathode. current density 0.3 0, 5 A / dm. Temperature 20 - 25. Duration of the process 5 - 10 s. The thickness of the coating depends on the duration of the process and the current density and is in the range of 0.03-0.1 mm. The content of Vicasol in the coating is determined by its thickness and is 0.05-0.08 weight. %

PRI me R 4. The product is degreased by known methods, washed with water and lowered into a bath with an aqueous solution of 4-tracer composition, weight. %:

Polyvinyl alcohol 8.0

Boric acid 0.4

Vikasol0,8

5 Water90,8

Cathode current density 0.3 0, 5 A / dm. Temperature 20 -. Duration of the process 5 - 10 s. The thickness of the coating depends on the duration of the process and the current density and is in the range of 0.03 - 0.1 mm.

The content of Vicasol in the coating is determined by its weight and is 0.05-0.8%.

The test results of coatings obtained from the known compositions and the proposed, are presented in table. one.

Adhesion of coatings obtained from the proposed and well-known (3 soils were estimated on a four-bedded chalet (the lower the score / the better the adhesion) by the method of lattice cuts (GOST 15140-69).

Comparative tests are presented in Table. 2

The data table. 2. testify that the adhesion is increased beyond the introduction of vicasol into the extract to the correct composition.

Sodium acetate

Tawliaa 1

60 WITH 70

Brilliant brilliant blast bum

Describing the surface of the surface after applying the incisions in the form of a lattice

3}

Peeling of the coating along the incision lines (up to 35% of the surface from each grid)

Claims (3)

Insignificant peeling of the coating in the form of points along the incision line or at the intersection points (up to 5% of the surface from each grid). in order to increase the stability against hydrogen sulfide corrosion, it additionally contains 2, 3-dihydro-2 methyl-1, 4 naphthoquinone-2 sodium sulfonate (vikasop) with the following ratio of components, weight. %: Polyvinyl alcohol 5.0 - 10, Boric acid 0.25-0.3 table 2 Scoring Vikasol0,1-0,3 VodaEsalnoe Sources of information taken into account during the examination 1.RJ Corrosion and corrosion protection, 1978, 4, 4К218П. 2.RZh Corrosion and corrosion protection. 1970, b, 6K399P. 3.Vlasyuk N.V. and others. Cathodic precipitation of polyvinyl alcohol gel. - Ukrainian chemical journal. 1976, 8, t. 42, p. 852.