DE2730645A1 - USE OF TELOMERISATS MADE OF MERCAPTANES WITH ACRYLIC COMPOUNDS AS STONE PROTECTION AND / OR CORROSION PROTECTION AGENTS - Google Patents

Description

Henkel IC 'Vfopcr

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Use of telomerizates from mercaptans with acrylic compounds as stone protection and / or corrosion protection agents

The operation of technical service water systems is generally without the use of anti-corrosion agents and Hardness stabilizers not possible. The classic means for this purpose are phosphorus-containing substances, such as polyphosphates or phosphonic acids.

The increasing importance of ecological problems in general Technology leaves the demand for phosphate-free corrosion and stone protection agents of increasing importance will. From this point of view, a number of phosphate-free organic polymers have recently been used Use as hardness stabilizers in service water systems has been described, such as: copolymers of maleic acid or their homopolysates and homopolymers and copolymers of (meth) acrylic acid and oxyacrylic acid. All these compounds are used in sub-stoichiometric amounts, the effectiveness of the substances mentioned is much lower than that of the classic phosphorus-containing compounds.

The object of the present invention was therefore to find more effective agents of the type mentioned which do not contain phosphorus Connections are and are therefore of considerable technical interest.

This object is achieved according to the invention by using telomerizates from telogens containing mercaptan groups

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Henkel Kommanciitgesc! «' _T \ on stocks

Sheet Q for patent application D - 5 "3 6" Ρ & βΤϋθ lind UtdfutUT

and acrylic blends as stone protection and / or corrosion protection agents solved in technical domestic water systems. The use of such telomerizates has proven to be beneficial proven, which have an average molecular weight between 300 and 3000, in particular 700 to 2000. They are expediently used in amounts of 0.1 to 100, in particular 1 to 30 ppm, based on the process water used.

The telomerizates to be used according to the invention can according to the general formula

(CH ₀ -C) _m H or

d ι m

CONH

S (CHo - C-H

R-

C I 111 C

COOM

and R is an aliphatic which optionally contains one or more carboxyl groups and / or hydroxyl groups Represents a radical having 2 to 22 carbon atoms and X = H or methyl and M an alkali metal ion and η and m whole Numbers are in an order of magnitude so that the above boundary conditions are met according to the molecular weight, and wherein the nitrile group can also be partially saponified to the amide group. The alkali metal ions come of course primarily sodium and potassium into consideration, of course these can also be wholly or partially by optionally substituted ammonium ion be replaced.

The production of the part to be used according to the invention

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Henkel limited partnership based on shares

Sheet 5 for the patent application η p ^ 66 Ρ & ΙβΜθ and UtOfatUr

27306A5

merisate can be carried out according to known methods (e.g. cf. U.S. Patent 3,498 9 ^ 2). Then the conversion of alkyl mercaptan, Acrylonitrile and acrylic acid in an anhydrous medium, such as in low molecular weight aliphatic alcohols such as methanol, Ethanol or propanol carried out. The reaction temperature can be between about 20 and about 100.degree. C. within wide limits be varied, but is generally between 20 to 70 ° C. The reaction is carried out in the presence of a customary Radical initiator, such as ammonium, alkali and / or alkaline earth persulfate, Lauryl peroxide, cyclohexyl peroxide or t-butyl peroxide. To work up the reaction product, the solvent is distilled off in vacuo, if necessary previously neutralized the acid or the carboxyl groups with an aqueous base such as sodium or potassium hydroxide or were partially neutralized. The telomerizate obtained in this way can usually be used without further purification suitable as a stone and corrosion inhibitor.

Accordingly, alkyl mercaptans can be used as starting materials for the production of the cotelomers to be used according to the invention preferably a straight-chain primary, branched-chain primary, secondary or tertiary alkyl group with 8 to 18 Carbon atoms, such as n-octyl mercaptan, n-decyl mercaptan, t-dodecyl mercaptan, hexadecyl mercaptan, octadecyl mercaptan to serve. Acrylic acid and methacrylic acid and the corresponding amides and in particular come as unsaturated monomers Acrylonitrile and methacrylonitrile are also possible.

The acrylamide telomerizates according to the invention include compounds the general formula

R.

CONH

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Henkel Kuii in; 3nciitgese:; 3chaft c p, ^ on shares

Sheet b _{2 for} patent application D Λ bb Patent® UfKl Üt8f 3'ί11Γ

to understand in which R is an aliphatic hydrocarbon radical having 8 to 18 carbon atoms, X is hydrogen or a Methyl group and m represent numbers from about 6 to 20.

The telomerization of the nonionic, i.e. amide and optionally Polymers containing nitrile groups takes place as already explained above. In this case, the work-up takes place the reaction mixture expediently by precipitation with solvents such as lower hydrocarbons or especially diethyl ether. In this way, by so-called If you fall over, cleaning must be carried out. in the in general, however, this is not necessary.

Although compounds of the type to be used according to the invention are considered as complexing agents per se their use is not obvious. It is well known to the person skilled in the art that the ability to form complexes A compound is not a benchmark for suitability as a stone protection agent (hardness stabilizer) or a corrosion inhibitor in domestic water systems. The excellent and well-known complexing agent (EDTA = sodium salt of ethylenediaminetetraacetic acid) e.g. is absolutely unsuitable as a stone protection agent (hardness stabilizer) in service water systems.

809884/0122

Henkel Kt »i · -'jeseilschaft auf Aktien

Sheet γ for patent application DS 5 ^ 6 PCtentO and literature

Production of the telomerizates to be used according to the invention

I) Cotelomerizate of acrylic acid and acrylonitrile Thioglycolic acid

61 », 8 g of acrylic acid (0.9 mol) and 31.8 g of acrylonitrile (0.6 mol) were mixed with 226 g of des. Water (35 # strength monomer solution) in a 1-1 three-necked flask with stirring to 60% ° C heated. 16.2 g of thioglycolic acid (0.15 mol) was added rapidly and then added dropwise 2.8 g ammonium peroxodisulfate, dissolved in 8 ml of V / ater within ¹ I minutes. The reaction mixture warmed up to about 90 ° C. in spite of being cooled with ice. After the reaction had subsided, the mixture was refluxed for a further hour. The solution was concentrated on a rotary evaporator, dissolved in the arm with aqueous ethanol and precipitated in ether. About 90 % of the telomer was dispersed in water, neutralized with dilute sodium hydroxide solution to pH 10, precipitated in ethanol and dried to constant weight in a vacuum drying cabinet.

II) Telomerizates from alkyl mercaptans and (meth) acrylamide

568 g of acrylamide (8 moles) and 202 g n-dodecyl mercaptan (1 mole) were charged with ¹ IOO ml methanol in a Ί-liter three-necked flask and heated with stirring to 50 ° C. 3.8 g of ammonium peroxide disulfate (0.5 % based on monomers) were dissolved in 500 ml of methanol and the solution was added dropwise to the reaction mixture over the course of 7 hours, the temperature being kept below 50 ° C. by cooling. After the reaction had ended, the mixture was refluxed for a further hour. In order to obtain the telomeres, some of which were still in solution, 2.5 liters of ether were used

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added as a precipitant and the precipitate formed is filtered off. The precipitate was extracted with acetone washed, filtered and in a vacuum drying cabinet until dried to constant weight.

The yield of telomers was 609 g (corresponding to 79 % of theory). The sulfur content of the product was 4.15 % and the distribution of the monomer fractions in moles in the telomer was 1 mole of n-dodecyl mercaptan: 8.6 moles of acrylamide (product A).

The following products were manufactured in a corresponding manner:

B) 1 mole of n-octyl mercaptan: 8.2 moles of acrylamide % S 4.39

C) 1 mole t-dodecyl mercaptan: 14.0 moles acrylamide % S 2.67

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Henk

Sheet 9 for patent application D 5566 ^^

Patents and literature Use according to the invention of the polyacrylic telomerizates example 1

For testing as a stone protection agent or hardness stabilizer, the following test set-up was used:

The test water with the substance according to the invention contained therein is passed through a heat exchanger by means of a hose pump promoted. The hardness deposited on the wall of the heat exchanger is dissolved in dilute hydrochloric acid and CaO in this solution determined by titration. The relation to a blank value without dosing is given:

Stone protection in % = 100 - % deposit, whereby the percentage deposit is calculated according to

Sample * 100 (mg CaO / 1) blank value (mg CaO / 1)

In addition, the following conditions were met: The test water had the following German degrees of hardness:

30 ° calcium hardness (as CaCl ₂ ) 56 ° carbonate hardness (as NaHCO ^) 10 ° magnesia hardness (as

Thermostat temperature: 80 ° C

Leaving water temperature: 70 ° C

Flow rate: 0.5 l / h

Flow volume: 1000 ml

Dosage of the stone protection

medium: 3 ppm

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on shares patents and literature

Table 1 below shows the values found for substance A in comparison with the so-called zero value reproduced.

Table 1

substance % Stone protection Blank value
Product according to I. O
62

Example 2

The determination of the corrosion behavior is based on the coupon method carried out. For this purpose, after a certain duration of the experiment, due to the corrosion process, it goes into solution Iron determined and in relation to a blank value without the addition of the products to be used according to the invention specified.

In Table 2 below, the corrosion protection is given in % , which is calculated

Corrosion protection in % = 100 % iron content.

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The percentage iron content is calculated according to:

Sample. 100 (mg Fe / 1) blank value (mg Fe / 1)

In addition, the following conditions were met:

Coupons:

Pickling of the coupons: sheet steel St 37> sandblasted with chilled cast gravel 0.1 -

0.2 mm

ρ coupon area 17.1 cm

200 cnr V / water (demineralized) 250 cm ³ H Cl cons. 50 cm ³ H NO ₃ conc.

Test water: 8 °

dH (as CaCl ₂ ) 2 "dH (as | O

dH carbonate hardness as NaHCO ₃ )

500 ppm chloride ion

pH during the experiment:

Test temperature: Duration of experiment: stirring speed: 6.5 to 8.2

20 ° C

3 h
100 rpm

Table 2 below shows the corrosion protection effects as a function of the acrylic telomerizates according to II

Specified in % .

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Table 2

substance Corrosion protection Blank value
Product II A
Product II B
Product II C 0
St.
HH
38

Example 3

A technical cooling system with a content of 1.2 nr and a circulation of 8 nr / hour. is operated with Düsseldorf city water. The essential analysis data were: total hardness 16 ° dH, of which carbonate hardness 8.5 ° dH at a pH value of 7, H and a chloride content of 165 mg / 1. The development is approx. 2 times. Without any formation of corrosion protection in the circuit water, an electrochemically measured corrosion rate of 0.18 mm / a is established in the system. Due to hardness deposits, the heat transfer at the heat exchanger is reduced from & t = 8 ° C to an At of H ° C within H weeks.

After the addition of the product II A in the amount of 30 ppm, a corrosion rate of 0.075 mm / a was established. The heat transfer showed no decrease during the test duration of 1 week.

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Claims (3)

Düsseldorf, June 30th 1S77 Henkel limited partnership Henkelstrasse 67 on shares patents and literature Dr. SchOe / Bk 27306AR patent application D 5566 Use of telomerizates from mercaptans with acrylic compounds as stone protection and / or corrosion protection agents Patent claims: 1. Use of telomerizates from mercaptan groups Telogen and acrylic compounds as stone protection and / or corrosion protection agents in technical Domestic hot water systems. 2. Use of telomerizates with an average molecular weight between 300 and 3000, in particular 700 to 2000, according to claim 1. 3. Use of telomerizates according to claim 1 and 2 in an amount of 0.1 to 100, in particular 1 to 30 ppm, based on the used water. Ί. Use of telomerizates according to Claims 1 to 3, where the telomerizate of the general formula / 2 809884/0122 Sheet 2 of the patent application Π ^f j 5 ^ 6 Henkel Kcn ;; 7 "^; icgcc2 on shares patents and literature - C) «- H RS- (CH _{2 -C 4 m} CN 27306A5 COOM and R corresponds to an aliphatic which optionally contains one or more carboxyl groups and / or hydroxyl groups Represents a radical having 2 to 22 carbon atoms and X = H or methyl and M an alkali metal ion and η and m whole Numbers are of an order of magnitude so that the boundary conditions according to claim 2 are met, and wherein the nitrile group can also be partially saponified to the amide group. 809884/0122