CH665845A5 - Korrosionsbestaendiger material. - Google Patents

Description

665 845

2nd

PATENT CLAIMS

Corrosion-resistant material based on a polyethylene containing a corrosion inhibitor, characterized in that polyethylene is plasticized with a mineral oil and an oil-soluble corrosion inhibitor:

a) Contact corrosion inhibitor:

a sulfated or nitrated mineral oil or a product of the neutralization of the sulfated or nitrated mineral oil with alkali or calcium hydroxide or a product of the neutralization of the sulfated mineral oil with urea or bubble residues after the distillation of synthetic or natural fatty acids or products of the condensation of these bubble residues organic amines or a product of the condensation of alkenylsuccinic anhydride and urea or b) corrosion inhibitor of the gas phase:

contains a salt of cyclo- or dicyclohexylamine and an organic acid or heteroalkylated lower amine or c) mixture of the contact corrosion inhibitor and the corrosion inhibitor of the gas phase as a corrosion inhibitor,

the mixing ratio of the corrosion-resistant material in mass% is as follows:

Mineral oil 20 to 45

Oil-soluble corrosion inhibitor 2 to 50

Polyethylene rest up to 100

DESCRIPTION

The invention according to the preamble of claim 1 relates to a corrosion-resistant material. The specified materials can be used in the manufacture of components used for sealing (sealing inserts, rings and washers, etc.), easily removable anti-corrosion coatings as well as for the production of foil materials and anti-corrosion packaging materials that are used for the preservation and packaging of metallic products.

Polymer films and coatings with a thickness of up to several millimeters do not prove to be an impermeable barrier for the diffusion of water, oxygen and electrolytes. The protective properties can be significantly increased by adding corrosion inhibitors to the polymeric substances.

By mixing the solutions or powders of polymers with corrosion inhibitors, which are compatible with the polymeric base, and subsequent heat treatment, corrosion-resistant materials for films and coatings based on cellulose esters, polyacetals, polyesters were produced. For example, a corrosion-resistant material is known which contains, as a corrosion inhibitor, a mixture consisting of amine nitrate and ammonium salt of an aliphatic carboxylic acid (US Pat. No. 3,462,329 Kl. 156-190, published 1969).

The disadvantage of the specified corrosion-resistant materials is the high cost of the polymer base and the limited nomenclature of the products to be protected.

Corrosion-resistant packaging materials are known, produced by extruding a mixture of polyethylene or another chemically resistant polyolefin with thermostable corrosion inhibitors, which comprise a mixture of inorganic salts of a-dicyclohexylamine, β-cyclohexylammonium nitrite, nitrosodicyclohexylamine (JAPS No. 12A-2223, published in JAPS No. 12-282, known as JAPS No. 12-282, No. 12-282, published in JAPS No. 12-282, No. 12-282, published in JAPS No. 12-282, No. 12-282, published in JAPS No. 12-282, No. 12-282, published in JAPS No. 12-282, No. 12-282, published in JAPS No. 12-282, No. 12-282, No. 12-282, known from JAPS No. 12-282, No. 12-282, No. 12-282, known from JAPS No. 12-282, No. 12-282, No. 12-282 known from JAPS no 1974).

Disadvantages of the known packaging materials are low values of the protective properties due to volatilization of the inhibitor during the production of the materials mentioned and because part of the inhibitor added is kept irreversibly in the polymeric film.

The corrosion protection properties of inhibitor-containing polymeric materials depend on the effectiveness of conveying the inhibitor to the surface of a metal to be protected.

The invention has for its object to provide a corrosion-resistant material based on a polyethylene and a corrosion inhibitor, which is characterized by an adjustable and time-stabilized deposition of the corrosion inhibitor on the surface of the product to be protected or in the cavity of a hermetic packaging material develop and consequently to increase the efficiency when using corrosion inhibitors and to increase the corrosion protection effect.

This object is achieved by the features of the characterizing part of claim 1.

The corrosion-resistant material according to the invention of the specified composition has a number of advantages, the main advantage being that an adjustable and time-stabilized deposition of the corrosion inhibitor onto the surface of a product to be protected or into the cavity of a hermetic packaging material is possible, as a result of which a high Corrosion protection effect is secured. (The corrosion rate of steel under foil or coating made of the corrosion-resistant material in the neutral medium does not exceed 10-4 g / [m2-hour].) The corrosion-resistant material according to the invention also has a wide range of physical-mechanical properties and is characterized by a production-oriented processing to products. For example, the material according to the invention can be used: to manufacture the components of sealing units which can inhibit the local corrosion of metallic components in the sealing units mentioned; for the production of a packaging film which protects metallic products against atmospheric corrosion during conveyance and storage; for the production of anti-corrosion agents (carriers for corrosion inhibitors of the gas phase) for arrangement within a hermetic packaging.

The corrosion-resistant material according to the invention is based on a gel-like system “polyethylene-liquid hydrocarbon plasticizer”. The mixture of the specified ingredients with an oil-soluble inhibitor changes to a homogeneous solution by heating to a temperature between 115 and 230 ° C (the temperature range is determined by the melting temperature and the initial temperature of the thermo-oxidative degradation of polyethylene). During the subsequent cooling to a temperature of 90 to 150 ° C there is an amorphous stratification, which is not accompanied by the complete phase separation due to the high toughness of the solution. The phase separation takes place on the microscopic sections comparable to those of super-molecular structures and causes the formation of a polymerization matrix with the system of pores which are filled with a liquid, low-molecular-weight filler (inhibitor solution in a mineral oil). The mentioned spontaneous separation of the liquid phase due to relaxation processes in the material is called syneresis.

The pore size of the polymerization matrix depends on the composition of the corrosion-resistant material according to the invention and the holding time at the temperature of the amorphous layer and is between 10 and 30 p.m.

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665 845

A necessary prerequisite for the transport of the inhibitor dissolved in the plasticizer to the surface of the product to be protected according to the syneresis mechanism is the presence of a system of communicating pores in the corrosion-resistant material. In the case of a contact corrosion inhibitor, syneresis is the only method of conveying the inhibitor onto the surface of the product to be protected, but the corrosion inhibitor of the gas phase is additionally transported by migration and diffusion within the polymerization matrix.

The formation of communicating pores reduces the maximum values of the strength and deformability of materials. However, the physical-mechanical characteristics of a plasticized and corrosion inhibitor-filled polyethylene are satisfactorily preserved for the purposes of its use as a sealing construction and packaging material, the polyethylene content exceeding 50%.

The upper and lower concentration limits of constituents are determined by a favorable combination of physical-mechanical and anti-corrosion properties of the material according to the invention.

For a plasticizer, the lower concentration limit (20% by mass) is determined based on the requirement that a syneresis process can take place, and the upper concentration limit (45% by mass) is determined by the condition that the physico-mechanical properties of the corrosion-resistant material is satisfactorily retained (the tensile strength of a packaging material must be at least 10 MPa and the elongation of the same must be 400%).

The lower (2% by mass) and the upper (50% by mass) concentration limit for an oil-soluble inhibitor results from the condition that a necessary protective concentration of inhibitor can be achieved on the metal surface, that the corrosion inhibitor is effective and that it is effective protective surface can be transported effectively. The upper concentration limit for the inhibitor is also determined by the effectiveness when using the inhibitor and the preservation of sufficient physical-mechanical properties of the material.

The corrosion-resistant material according to the invention is produced as follows. An oil-soluble corrosion inhibitor is mixed with a plasticizer (mineral oil) until the inhibitor is completely dissolved in the plasticizer. The solution obtained is mixed with granulated polyethylene in any mixer, for example in a drum mixer. The mixture obtained is processed into the corrosion-resistant material by melting this mixture and then extruding or injection molding or coating using a dipping process. Construction sealants are produced by injection molding and an inhibitor-containing film is produced by extruding the molten mixture.

Low-density (p = 900 to 939 kp / m3) or high-density polyethylene (p = 949 to 959 kp / m3) is used to manufacture the corrosion-resistant material.

The following mineral oils, which are conditionally designated by letters a, b, c, are expediently used as plasticizers for polyethylene:

a - a mineral oil without additives from selective refining, made from low-sulfur paraffinic or low-paraffin oils with the following main data: density at 20 ° G 0.89 g / cm3, toughness at 20 ° C 14-IO-6 mVS, ash content at most 0.003% , Acid number 0.25 mg / KOH g, pour point minus 30 ° C, flash point in a closed crucible 200 ° C;

b - a mineral oil without additives from selective refining, made from mineral oils with low sulfur content with the following main data: density at 20 ° C 0.897 g / cm3, toughness at 20 ° C 20.5 • 10-6 m2 / S, ash content at most 0.003%, Acid number 0.03 mg / KOH g, pour point minus 18 ° C, flash point in a closed crucible 250 ° C;

c - highly purified mineral oil distillate with the following main data: density at 20 ° C 0.894 g / cm3, toughness at 20 ° C 49-10- «mVS, at 50 ° C 20-10-« mVS, pour point minus 45 ° C, flash point in open crucible 163 ° C.

For example, the following of oil-soluble contact corrosion inhibitors based on sulfonated or nitrated mineral oil are effective with the letters A, B, C, D:

A - a nitrated mineral selective raffinate oil, thickened with paraffin (10% by mass), which is an oily dark brown liquid with 0.96 g / cm3 density at 20 ° C, 100-10-6 m2 / S viscosity at 20 ° C and 30 Represents -10-6 m2 / S at 100 ° C, 3.5% ash content and is soluble in mineral oils and organic solvents;

B - an oily solution of calcium sulfonate and oxidized petrolate, with a toughness of 32 to 40-10-6 mVS at 100 ° C, an acid number of 0.04 mg / KOH g, an ash content of 9%, which in mineral oils and organic Solvents is soluble.

C - sodium sulfonate, obtained by neutralizing sulfonic acids contained in sulfated oil distillate with caustic soda, with a density of 0.961 g / cm3 at 20 ° C, a toughness of 230-10-6 m2 / S at 100 ° C, an acid number of 0, 04 mg / KOH g, an ash content of 9%;

D - a nitrated mineral oil that is calcium hydroxide neutralized and stearin thickened (10% by mass) and an oily black liquid with a toughness of 100-10-6 m2 / S at 100 ° C 0.96 g / cm3 density at 20 ° C, Represents 4.6% ash content and is soluble in mineral oils and organic solvents.

For example, the following of oil-soluble contact inhibitors based on the bubble residues obtained in the distillation of synthetic or natural fatty acids are effective.

E - a salt of cyclohexylamine and synthetic solid acids with a chain number of carbon atoms between 7 and 11 (C „H2n + iCOOC6HnNH2); the specified salt is a pasty light brown substance with a pour point of minus 12 ° C, soluble in alcohols, mineral oils, petrol, acetone;

F - a bubble residue obtained from distilling fatty acids from soap stocks of black cotton oil and bone fat; it consists mainly of high molecular weight saturated and unsaturated fatty acids and contains a certain amount of non-split fats and oxidation products of fats and fatty acids, whereby compounds with Ciò ... C24 long chains predominate; the density of the bubble residue is 0.90 to 0.95 g / cm3 at 20 ° C, the toughness 65 to 70-10 ~ 6 m2 / S at 50 ° C, the acid number 62 mg / KOH g, the flash point in the open cup 260 ° C.

A condensation product of alkenylsuccinic anhydride and urea has also proven to be an effective contact corrosion inhibitor (conditionally labeled with the letter G). It is a light brown liquid with 0.89 g / cm3 density at 20 ° C, 25 • 10-6 m2 / S viscosity at 50 ° C, soluble in mineral oils and organic solvents. '

Oil-soluble corrosion inhibitors of the gas phase, for example, have the following effects, which are conditionally designated by letters H, I:

H - a salt of dicyclohexylamine (at least 43% by mass) and technical fraction of synthetic fatty acids with a chain number of 10 ... 20 carbon atoms; the salt mentioned is a pasty product with a density of 0.91 to 0.92 g / cm3 at 20 ° C, 15 to 20 ° C melting point5

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665 845

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temperature, in mineral oils and organic solvents

lien, the riDcniiîtcii DctriEt o, oi] n dci io t;

I - a yellow to light brown liquid based on technical fraction of secondary amines of fatty acids and acrylonitrile; the specified product has a general formula

/ NCH2 - CH2 - CN,

H

where R is for CnH2n + i, n = 7 ... 9;

the density is 0.85 g / cm2 at 20 ° C, the toughness 6 • 10 "6 mVS at 40 ° C, the pour point minus 40 ° C, the boiling point 190 ° C at a pressure of 1.33 kPa, the flash point l ° c, above all mineral oils, Altonolcn, orpnfc see solvents, water soluble, the volatility is 13.3 Pabei20 ° C.

5 A mixture of a contact inhibitor and a corrosion inhibitor of the gas phase is expediently used to produce a corrosion-resistant material for the preservation and packaging of metallic products.

For a better understanding of the present invention, the following examples of the specific compositions of the corrosion-resistant material according to the invention and the known corrosion-resistant material according to JA patent specification No. 49-21223 are given.

Table 1

Components Compositions of the corrosion-resistant material in mass%

I II III IV V VI VII VIII IX X XI XII XIII XIV acc.

YES-

Patent Specification No. 49-21223

I 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

Lower polyethylene - - - 50 65 53 58 50 53 20 30 - 30 50

density

High density polyethylene 45 55 65 - - - - 58 - - - - 30 - Mineral oil a 45 37 29 - - - - 20 - - 30 -

b - - _ 41 - - 27 - 30 - - 20 - -

c 25 45 - - - 30 - - 20 20 -

Contact corrosion inhibitors

A - 20- - 10 -

B io - - - - - - - -

C __6 ------------

D --- 9 -----------

E - - - - 6 - - - - 15 - - - - -

F ________ 20 - - - -

G ----- 2 12 22 - - 10 ---

Corrosion inhibitors of the gas phase

H ------ 3 ______ 40-

I ---- 4 ---- 2 30 40 50 -

Mixture of 1: 1 1: 1- - - - - - - - - - - - 50

a-dicyclohexylamine,

ß-cyclohexylammonium

nitrite and

Nitrosocyclohexylamine in mass ratio

The properties of the corrosion-resistant material according to the invention of the compositions from I to XIV and of the corrosion-resistant material according to JA Patent No. 49-21223 are summarized in Table 2.

The tensile strength and elongation at break in the tensile test were determined on a tearing machine with a moving speed of 50 mm / min of a movable gripper.

The corrosion tests were carried out using the rapid method by measuring the polarization resistance Rpoiansation of a two-electrode transmitter in contact with the test specimen of the material to be examined in the electrolyte. The electrodes used were made of carbon steel with 0.09 to 0.15 mass%

Carbon have been produced. Effective electrode surfaces were ground to between 0.4 and 0.5 [lying roughness Ra, and non-actuated electrode surfaces were insulated with paraffin. The 1 n solution Na2SC> 4 served as the electrolyte. The corrosion rate «i» in g / (m2-hour) was calculated according to the formula

60

j _ 2 KGweight S.Rpolarization determined, where KGweight - a weight coefficient of corrosion, which depends on the type and concentration of the electrolyte, is in ohm-g / hour (with 1 n • solution NaîSCh, KGweight is 0.032), Rpoiansation - a polarization resistance in ohms and S - a surface of mutual electrical

the covering in m2 means “Zaschita metallov” No. 6, 1982 edition, “Nauka” publishing house, Moscow: V.A. Goldade, Ya.M. Zolotovitsky, A.S. Neverov, L.S. Pinchuk: "Otsenka zaschitnoi sposobnosti ingibirovannykh materialov metodom polarizatsinnogo soprotivlenia", pp. 946-949).

Table 2

Composition No.

1

Breaking stress in tensile test in MPa

2nd

Elongation at break in%

3rd

Corrosion speed of a steel electrode when it comes into contact with the film made of a corrosion-resistant material in 10-3 in 10 ~ 3 g / cm2 hour)

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I.

13.0

0.17

II

14.2

-

0.28

III

17.1

-

0.65

IV

12.3

400

0.15

V

15.4

480

0.3

VI

12.8

550

0.6

VII

13.2

450

0.5

VIII

14.4

-

0.25

IX

11.1

-

0.31

X

12.2

-

0.44

XI

2.1

-

0.15

XII

3.5

-

0.11

XIII

3.3

-

0.2

XIV

3.7

-

0.25

according to the

YES patent

font

No.

5.8

-

7.4

49-21223

As can be seen from Table 2, the physical-mechanical properties of the corrosion-resistant material can be regulated in a wide range by changing the compositions. In the material according to the invention, the breaking stress during the tensile test changes from the values approximating the strength of the polyethylene (compositions I to X) to the values characteristic of solid lubricants (compositions XI to XIV). The elongation at break was determined in compositions IV to VII on the basis of low-density polyethylene, which is necessary for the production of an inhibitor-containing

665 845

Foil are recommended. This characteristic value (400 to 550%) corresponds to the requirements placed on preservation and packaging materials.

Compositions I to X are recommended for the production of sealing building materials, compositions IV to VII also being suitable for the production of inhibitor-containing films which are used in the preservation and packaging of metallic products.

The compositions XI to XIV with a high content of corrosion inhibitors in the gas phase are recommended for the production of corrosion-protective packaging materials.

In contrast to the material according to the invention, the corrosion-resistant material according to JA patent specification No. 49-21223 can be used as a corrosion-protecting packaging material due to its strength properties,

however, do not use for the manufacture of structural sealing elements and products.

According to the information in Table 2, the rate of corrosion of a steel electrode which is in contact with the film made from the corrosion-resistant material according to the invention (compositions I to XIV) is 12 to 50 times lower than that of the corrosion-resistant material according to JA Patent No. 49 -21223.

The use of the corrosion-resistant material according to the invention in seals for petroleum and natural gas equipment makes it possible to increase the service life of the sealing units for pump and compressor pipes, pump piston rods and shafts by reducing crevice corrosion and the corrosive and rubbing wear of metal by 1.5 to 2 times to extend. The inhibitor-containing film, produced from the corrosion-resistant material according to the invention, is recommended for the preservation of the spare parts of machines and equipment as well as the machine tools by hermetic coating or thermal vacuum forming. The corrosion protection element, which is made from the corrosion-resistant material according to the invention and is introduced into the interior of a hermetic packaging, protects metallic products against corrosion even when they are packaged in a film which contains no inhibitors.

The corrosion-resistant material according to the invention is therefore characterized by a high degree of protection of metallic products against corrosion as a result of the effective use of corrosion inhibitors and by a wide range of uses thanks to a wide range of physical-mechanical properties.

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G