DE1621567A1 - Cleaning solutions and processes for cleaning metals - Google Patents

Description

Metals

The invention relates to an aqueous solution that is used for cleaning of metal surfaces, and refers to a improved method for removing iron oxides and hardness deposits from metal surfaces. In particular concerns the Invention alkaline solutions containing ammonium or amine polycarboxylate chelating agents or complexing agents.

In the following description and in the claims

Nitrogen-containing polycarboxylic acid chelating agents and Polycarboxylic acid metal complexing agent with no nitrogen in the molecule called polycarboxylic acid metal complexing agent

There have been cleaning procedures to remove Elaenojcyd- and hardwood deposits a & tilleflllch of AblajS $ ruag * n

_ ——— £

• ORIGINAL BATHROOM.

109820/1947

au »carbonates and sulphates of calolum and magnesium, whereby Deposits of copper or copper compounds may be present « proposed of metal surfaces in which an alkaline Solution of a polycarboxylic acid instead of an aqueous mineral acid solution However, these polycarboxylic acid chelating agents or chelating agents tend to damage the metal substrates to corrode when the deposits dissolve, in particular at the temperatures prevailing in the usual catfish. It is highly desirable to have such an attack on the metal to a minimum, all the more when a sealed vessel or a sealed system is numerous Times during an expected operating time.

The invention is based on the finding that an aqueous metal cleaning solution with a pH between 7 and 10 containing 0.5 to 40 wt .- ^ of a polycarboxylic acid metal complexing agent, then against a corrosive attack on a metal substrate in contact with this is inhibited, the cleaning effect of the solution is not affected to any significant extent when the solution at least one thioethylamine of the formula I.

A - S:

CH ₂ CHRNH

wherein A is hydrogen, a lower alkyl group or a radical of the formula II

10 9820/1947

R «NH (CHg) _n - II

where R ¹ denotes a lower alkyl group "X 1 or 2 is, R each independently represents hydrogen or a lower alkyl group and symbolizes Nl to 8" or the hydrosulfide salt or a thioithylamine of the formula III

S ^ NR III

in which R each independently of one another is those given above Has meaning and ö means 1, 2 or 3 «added will. .

It is particularly advantageous if the solution is bis (2-aminoethyl) sulfide contains. It is also advisable to prepare a solution the 0.01 to 0.20 and preferably 0.03 to 0.15 wt .- ^ an amine-ketone-aldehyde-fatty acid adduct contains «that through Bringing together 1) 1 get of an ammonia derivative with at least one active hydrogen "which is linked to nitrogen" that no other reactive ones under the reaction conditions Groups other than hydrogen have 2) 1.5 to 10 parts of a ketone with at least one hydrogen atom on the carbon atom " which is adjacent to the carboxyl group «3) 2 to 10 Hol one from aliphatic aldehydes with 1 to 16 carbon atoms or

109820/19 * 7 ^ ■ p

aromatic aldehydes of the benzene series existing aldehyde which has no other functional groups except the aldehyde groups, and 4) 0.6 to 24 parts by weight, based on 1, 2 and 3, of a fatty acid having 1 to 20 carbon atoms is produced, the Contacting is carried out at a temperature of about 66 to about 121 ^° C (150 to 250 ^° F) for a period of about 1 to about 16 hours. The use of the combination of the thioethylamine or SCCN-type inhibitor with the complex reaction product has the advantage that the total amount of inhibitor required is reduced to a minimum, since the combination has a synergistic effect on protecting the metal substrate against corrosion that is, the combination is more effective than any single acting inhibitor material on its own, the effect of which is precalculated on a weight basis taking into account the same effect.

The sewing part of the combination is that it is colored black Surface film or a © sotoapze equipment on the cleaned Surface leaves · This® combination can then not to be used «if a light one after cleaning Surface should be preserved.

The invention therefore relates to new solutions and an improved one Process for cleaning metal surfaces.

109820/1947

Of suitable polycarboxylic acid chelating agents, the alkylenepolyamine polyacetic acids of the formula are selenium

(HOOCCH ₂ ) _a N (CH ₂ ) ^

mentioned, where η 1, 2, 3 or 4 and m 0> 1, 2, j3 or 4 and one or two of the carboxymethyl groups by one β-hydroxyethyl group and one or more of the carboxyraethyl groups can be replaced by carboxyethyl groups. As specific examples of such acids, the particularly suitable can be ethylenediaminetetraacetic acid (ÄDTE), N-hydroxyethylethylenediamine triacetic acid, nitrilotriacetic acid, N-2-Hydroxyäthyliminodiacetic acid, Dläthylenetriatninpentaacetic acid as well as mixtures of these acids. Examples of suitable polycarboxylic acid complexing agents without nitrogen in the molecule are citric acid and tartaric acid.

The inhibitors used in this invention are essentially contain all Äthylenimlne or polyethylene polyamines, ate divalent sulfur in the molecule * They are usually produced by reacting hydrogen sulfide with ethyleneimine in different proportions "

It is essential that each of the thioethylamine inhibitor compounds the S-C-C-N group in the molecule contains »Such compounds are all liquids at room temperature * They are in the concentrate

109820/1947 © ad

trations in which they are used as inhibitors, easily soluble in water. Usually, these inhibitors are effective and stable at temperatures up to 200 ⁰ C. At temperatures below 6O ⁰ C inhibitors are also effective, "but they are not normally used at such temperatures. The inhibitors according to the invention are advantageous because they do not precipitate out of the aqueous cleaning solution according to the invention on long standing and are effective for cleaning times of at least 12 hours.

Examples of specific sulfur-containing amines are bis (2-aminoethyl) sulfide, bis (2-aminoSthyl) disulfide,> aza-6-thiaootane-1,8-diamine, Beta-meroaptoethylamine, thiazolidines 2- (Aminoäthylthio) ethanol, thiazole-2,2-dimethylthiazole and the hydrosulfide salts of these compounds. Suitable classes Amines containing sulfur are: polyalkyleneamine sulfide, polyalkylenearain disulfide, Polyalkyleneamine mercaptan, hydroxyalkyl " polyalkylene amine sulphide «Polyalkylene polyamine sulphide, polyalkylene polyamine disulphide and polyalkylene polyamine mercaptan. links from any of these classes can be used as hydrasulfide salts

The sulfur-containing amine inhibitor according to the invention, the has the S-C-C-N- group, can furthermore in combination with the adduct, which is produced by chemical reaction of equimolar amounts of TallÖlfettsKure «epichlorohydrin and

BATH ORIGINAL

109820/1947

_ ₇ _ 1821567

one of ethylene diamine, diethylene triamine, triethylene tetramine, tetraethylene pentamine, pentaethylene hexamine or hexaethylene heptamine existing intralinear ethylene araine or mixtures of two or more such amines. That Adduct is made by reacting tall oil fatty acid with approximately 10 moles of epichlorohydrin per mole of the fatty acid. To the reaction, the excess epichlorohydrin is stripped off by flash distillation. Then there will be a large excess of the intralinear ethylene amine was added to react with the epoxy product, whereupon the excess was again flash distilled is stripped. The desired product is left behind.

The adduct of the intra linear ethylene amine vxird in a concentration from 0.005 to 0.02 wt -.%, And preferably "The sulfur-containing amine, at a concentration of 0.001 to 0.01 wt .- ^ that described in combination with the adduct of intralinear ethylene amine is used, is in a concentration between 0.005 to 1 wt -. $, and preferably in an amount of 0.01 to 0.05 wt .- ^ used "Preferred combi nations are · l) of bis (2-am ± noäthyl ) sulfide with the adduct of tall oil fatty acid and epichlorohydrin with triethylenetetranin and 2) bis (2-atninoethyl) sulfide with the adduct of tall oil fatty acid and epichlorohydrin with tetraethylene pentamine «

For the practical use of the solutions of this chelating

109820 / 1SA7 bad ORiGtMAS.

agents used for metal cleaning processes,
the solutions are usually made alkaline to a pH between 7 and 10 by adding the required amount of a nitrogen base such as ammonia, an alkanolamine, or other suitable amine. Examples of suitable combinations of alkylenepolyamine polyacetic acids with nitrogen bases are listed in the table below?

PolyesslgsSure Ä'DTE ÄDTE Xotb ÄDTE ÄDTE ÄDTE Ä'DTE fiDTE fiDTE Ethylenediamine tetrapropionic acid N, N-Di (ß-hydroxyethyl) -glyoin

Nitrogen base

y tetraacetic acid

(a-Hydroxyäthylimiao) diess ig-

Ammonia fithanolamine fithylamine fithylenediamine Diethylenetriamine pentaethylene hexamine dimethylamine trimethylamine ethylene imine fithanolamine fithylenediamine

Ammonia ammonia

BATH

ORIGINAL

109820/19

The complexing agents, which do not contain nitrogen in the molecule, are combined in a similar manner with a nitrogen base such as ammonia or an amine. Aqueous solutions of these metal chelators typically need to be used at a temperature above 90 ⁰ C and preferably at a temperature above 100 ⁰ C * so that iron oxide and hardness deposits within reasonable periods of time can be removed.

For the preparation of the inhibited solutions according to the invention the inhibitor can be used directly before or after the addition of the polyearboxylate, the ammonia or the ammonia derivative are dissolved in the water used. It is usually convenient dissolve the inhibitor in such an amount of water, that a 1 to 10 wt .- ^ - strength solution is obtained, whereupon for To achieve the desired concentrations, the required amount of such a premix is added to the cleaning solution.

To carry out cleaning of metal with the inhibited cleaning solution according to the invention, the system to be cleaned is filled or otherwise brought into intimate contact with the cleaning solution. The cleaning solution is heated to a temperature between 90 and 200 ⁰ C and kept at such a temperature until iron oxides and /

109820/1947

- ίο -

or hardness deposits are essentially dissolved. At these temperatures, copper deposits from dissolved copper, if any, are deposited on the cleaned surface in the form of metallic copper "By adding an oxidizing agent to the cleaning solution, copper is dissolved and its complete removal is ensured." Sodium nitrite or potassium chromate or preferably air is added to the cleaning solution to oxidize the copper to a soluble salt. This is preferably done after completion of removal of iron oxide and hardness deposits when the temperature of the cleaning solution to below 85 ⁰ C and preferably reduced to 60 to 70 ⁰ C.

The cleaning process is done by rinsing the cleaned Metal surface finished with water.

A major advantage of the present invention is the effectiveness of the inhibited solution in terms of dissolution and removal of iron oxides and hardness deposits as well as the removal of metallic copper or Copper oxide deposits without significant corrosion of an iron metal substrate. The inhibited Solution is also capable of iron oxides and hardness levels remove * without corrosion of a copper substrate occurring »

BATH ORIGINAL

109820/1947

To the composition of the cleaning solution according to the invention as well as to show the cleaning method according to the invention, a series of tests are carried out · With each test, clean « weighed metal strips made of an unalloyed steel (SAE, 1010 type) placed in a bottle containing 200 ml of an inhibited aqueous solution from ÄDTE contains. The ÄDTE solution always contains 3.8% by weight of JU) TE, a sufficient amount Ammonia, in order to adjust the pH of the solution to 9.2, and one of the inhibitors according to the invention or one of the inhibitors according to the invention Inhibitor combinations · Each test uses a pressure reactor consisting of a short tube with a large Diameter with a concave hemispherical closed end or bottom and a screw-on lid for the open End exists. In any case, the beaker in which the solution and the strips are located is placed in such a pressure reactor given, whereupon the reactor contents are heated to 95 ° C for 4 hours and kept at this temperature value under Eigenendruok will. After this test period, the strips will turn off removed from the reactor, cleaned, dried and weighed again · The weight losses are extrapolated to g / cm / day »The used Inhibitors * the inhibitor concentrations observed and the weight losses determined are in in Table I below.

No inhibitor is used in a comparative test. The results these tests are also listed in Table I.

109820 / 1-947 '

Table I.

Test no ο

Inhibitor

Wt -.% ⁺ F% additive by weight.

Corrosion speed

2
jg / cm. / day

Compare none

1 '■ "^ ⁺ MLLs Chung A'

2 bis (2-aminoethyl-

0.2

O ■ '■ 3 Beta-mereaptoethyl
amine O, ² oo 4th Bis (2-aminoethyl) -
sulfide O, 0667 O 5 Bis (2-aminoethyl) .-
disulfide 0, 0667 β
7th Beta-meroaptoethyl
amine
η 0 _g
O ₃ 0667
04

0.133

0.133

0.0125 0.0007 0.0007 0.0024 0.00026 0.00033 '0.00013 0.00017

ZO

The additive is the product of the reaction of rosin-amine D, tall oil fatty acids, acetophenone and paraformaldehyde at a temperature of approximately 95 ° C. for a period of 8 hours in a medium composed of ethylene glycol and in the presence of H ₂ SO ₂ , »Nach an adduct of nonylphenol and ethylene oxide is added to the reaction product,

Mixture A = 70% ~ bis (2-aminoethyl) sulfide plus 30 wt .- # 3-thia <= 6 * »azaoctane <= l wt., 8-diamine.

A second series of tests is carried out in the same as in the first catfish Teetrelhe, wherein the erflndungs · proper inhibited solutions are used, with the exception that the Testemperaturen either 150 ⁰ C or l6o ° C. Comparative tests are carried out using 1) no inhibitor and 2) a commercially available Arain-ketone-aldehyde-fatty acid adduct, which is already described above and in the footnote of the table. A series of tests are rerun using the mean of the results obtained. The inhibitors used, their concentrations, the proverbial additive concentrations, as well as the Korrosionsgesehwindigkeiten which are observed at 150 ⁰ C are summarized in Table II below. The speeds determined at 160 ° C. can be found in Table III.

109820/1947

O CS ■ Η fH Co> s

Ot HI HI

• Η JQ

KN σι O fc * - in in KN σ » CVl O ■ sl · H Ql O KN 8th} ο 8th 8th 8th O
O O
Q O O
O ο
ο Ä O ο O O 8th O O
O O ο ο O O

σ \

O O O O O O O O

O O

B-1

ο *

ε-

οο νο ο ο

δ I

t- 00 O O

in S m

KN VQ KN

Ir UN KN KN -si- KN

ί O O O O O

O O O O O O O

A ^ t id ιη

O O O O

«4 =» at «»

O O O O

0} ¹ O • ΗΉ

ο ta ^>

ο}

ti K ε:

O H CXI KN- * in VO 00 CJ \ H HH H H H H c * - co σ \ ο

H H iH CVI

BATH ORIGINAL

109820/1947

O
CO
CO

T a b e Inhibitor lie II ^ continued) ⁺ Additive, Korros ionsges chw ,.
ρ
ίζ / οπι / TaR test
No. Mixture D Wt .- ^ 0.1 0.00054 21st Mixture E 0.05 0.1 0.00024 22nd 2- (Aminoethylthiosulfide) -
ethanol 0.05 0.0555 0.0267 25th η 0.067 0.0567 0.0155 24 η 0.0755 0.04 0.00166 25th ^η 0.08 0.05 0.00167 26th 0.1

The additive is the reaction product of Bosln-Arain D, tall oil fatty acids. Acetophenone and which is. Long performed approximately at a temperature of about 95 ⁰ C for 8 hours in a Ithylenglykolmedium in the presence of HgSO ^ paraformaldehyde. After the reaction, an adduct of nonylphenol and ethylene oxide is added to the reaction product.

a The ⁿ additive material ⁿ is used alone, without a sulfur-containing amine according to the present invention.

Mixture B "90.9 wt * - £ of HgS salt of bis (2-aminoethyl) sulfide and 9.1 wt -.% Ethanol.

Mixture C »84.8 wt * - £ bis (2-aminoethyl) sulfide, 1.5 wt .- ^ of the -E ^ S salt of bis (2-amino-

ethyl) sulfide and 15.6 wt .- # 5-thia-6-azaoctane-1,8-diamine. _.

CD '~ **

Mixture D = 84.8 wt .- ^ bis (2-aminoethyl) sulfide and 15.1 wt .- ^ ^ -Thia-6-azaoctane-1 ^ S-J ^

O i diamine. - *

3 · ■ cn

'Ά \ mixture ε = 84.8 wt .- ^ bis (2-aminoethyl) sulfide, 5.2 wt .-% of the HpS salt of bis (2-amino-cn

§ j ethyl) sulfide and 10.0 wt .- ^ 5-thia-6-azaoctane-1,8-diamine. ^ 4

Table III

OO ISJ O

test
No. Inhibitor a Wt .- ^ "Additive, Corrosion visible
"/ Cm / Ta" 1
H comparison - Bis (2-amlnoethyl) ■. 0.133 O\
I. comparison η 0.1 0.0154 27 Thiazolidine 0.05 0.1 0.00093 28 Bis (2-aminoethyl) sulfide 0.04 0.08 0.00088 29 0.05 0.1 0.0342 30th 3-thia-6-azaoctane-1,8-diamine 0.04 0.08 0.0070 σ? 31 Mixture B 0.05 0.1 0.00185 N)
cn
CD 32 ti 0.05 0.1 0.00073 33 η 0.066 0.134 0.00093 34 t! 0.05 0.1 0.00068 35 H ₀ S salt of bis (2-amino-
^d ethyl) sulfide
η 0.04 0.08 0.00049 36 Mixture C 0.0366 0.0733 0.00029 37
38 0.0366
0.05 0.0733
0.1 0.00098
0.00078 39 0.04 0.08 0.00151

test
No. Inhibitor 40 Mixture C 41 Mixture D 42 η 43 Mixture E 44 dd 45 Bis (2-amine 46 Cl

Weight -

Additive, wt .- ^

Corrosion rate g / cm / day

O CO OO

0.05 0.04

0.05 0.04

0.05 0.08

0.1

0.1 0.08 0.1 0.08 0.1 0.04 0.05

0.00039

0.0194

0.00083

0.00122

0.00044

0.00717

0.0247

The additive is the product of the reaction of rosin-amine D, tall oil fatty acids, acetophenone and paraformaldehyde at a temperature of about 95 ° C, the reaction being carried out for about 8 hours in an ethylene glycol medium in the presence of HgSO ^ will. After the reaction, the reaction product becomes an adduct of phenol and ethylene oxide added.

a The "additive material" is used, and not a sulfur-containing amine.

measured the present invention. ^

Mixture B = 90.9% of the HgS salt of B ± s (2-aminoethyl) sulf Id and 9.1% by weight of ethanol. ^

Mixture C = 84.8 wt .- ^ bis (2-arainoethyI) SuIfId, 1.5 wt .- ^ of the HpS salt of bis (2 "amino - ^

ethyl) sulphide and 13.6% by weight of 3-thia-6-azaoctane-1,8-diamine. S.

Mixture D s 84 o wt -.% Bis (2-aminoethyl) sulfide and 15.1 wt .- ^ 3-thia-6-azaoctane-l _# 8 dlamifö

Mixture E = 84.8 wt .- ^ bis (2-aminoethyl) 3 ulfide, 5.2 wt .- ^ of the HpS salt of bis (2-amineQ- ^ ³

ätbyl) aulfid and 10.0 wt .- ^ 3-thia-6-azaoctane-1,8-diamln.

In the same way as in the 1st and 2nd series of tests, a
3rd series of tests carried out using the inhibited solutions according to the invention * with the exception that cleaned and weighed copper strips instead of steel strips are exposed to the action of the solutions. Temperatures of 150 and 155 ^° C. are used. The inhibitors used and the corrosion rates observed are summarized in Table IV. Some values represent average values
were determined from several tests.

In addition, comparison tests are carried out, with 1) no inhibitor and 2) the amine-ketone-aldehyde-fatty acid adduct described above be used. The results of the comparison tests are summarized in Table 2V.

These tests show that copper surfaces, such as heat exchanger tubes, which are used in high pressure steam boilers, attacked only slowly by the cleaning solution according to the invention so that the method according to the invention is a safe method for cleaning such boilers.

ORIGINAL 109820/1947

Tabel

IV

Weight «^

litive temp, ⁰ C corrosion resistance

BATH same ■ ttM Wi t * N a mn mm w , WfcaäB 150 0.0102 I. CD
NJ O Ver
same ΐ
ι
ί Bis (2-aminoethyl) sulfide
(raw) 0.05 0.1 150 0.0099 I. OI
CD ο 47 ' Bis (2-aminoethyl) sulfide 0.05 0.1 150 · 0.00166 co
09
IO 48 Mixture 0 0.05 0.1 150 0.00039 O
■ ν, 49 Mixture D 0.05 0.1 150 0.00088 co 50 BK (· «· \ 1 \ t 0.1 150 0.00039 ■ -J Ver
same Bis (2-aminoethyl) sulfide 0.05 - «=. <* ■ 155 0.0108 51 Mixture C 0.05 0.1 155 0.00034 52 Mixture E 0.05 0.1 155 0.00029 53 0.1 155 0.00024

⁺ The additive is the product of the reaction of rosin-amine D, tall oil fatty acids, acetophenone and paraformaldehyde, which is carried out at a temperature of about 95 ° C for about 8 hours in an ethylene glycol medium and in the presence of HgSO ^ »After the reaction, a Adduct of nonylphenol and ethylene oxide added to the reaction product.

a The "additive material" is used and not a sulfur-containing amine according to the present invention *

Mixture C = 84.8 wt .- ^ bis (2-aminoethyl) sulfide and 1.5 wt .- ^ of the H ₂ S salt of bis (2 = aminoethyl) sulfide and 13.6 wt = - # J-

Mixture D = 84.8 wt -.% Bis (2-aminoethyl) sulfide and 15.1 wt .- #> = thia-6-azaoetan-l, 8-diamine.

Mixture E = 84.8 wt .- # bis (2-aminoethyl) sulfide, 5.2 wt .- ^ of the HgS salt of bis (2-aminoethyl) sulfide and 10.0 wt .- ^ 3-thia-6-azaoctane-1,8-diamine.

In a fourth series of tests, which is carried out in the same way as the first and second series of tests, with the exception that the steel strips are polished, bis (2-aminoethyl) sulfide is used as the only inhibitor substance, the temperatures between 115 and 171 ⁰ C. The test solution contains 10 wt .- ^ ADD, while the test periods are 16 hours. The results of the tests are summarized in Table V below "

109820/1947

Table V

Test Bis (2-aminoethyI) - Temp «C Mr. sulfld, Qew.-g; -

Corrosion rate / ß /

54 * 0.01 115 55 0.02 115 56 0 * 05 115 57 0.02 128 58 0 * 05 138 5th series of tests

0.0033 O, 000044

0.0025 0.0026 0.01297

A fifth series of tests is carried out in the same way as the fourth series of tests, with the exception of: " that an intralinear Ethylenamine adduct in all test solutions with the exception of one solution is added. Each of the test solutions contains one of the sulfur-containing amines in the composition according to the invention is used * The adducts used and their concentrations, the concentration of the bis (2-aminoethyl) sulfide used, the temperatures maintained and the corrosion rates extrapolated on a 24 hour basis are summarized in Table VI below. Some adduct and inhibitor combinations will not work for everyone the specified temperatures tested

1098 20/1947

Tabel

VI

test use Weight "% Gew ~ j »bis (2 ~ amino ~ Ib Corrosion rate <, a / cm / day 0.0022 carried out. ^a 130 ° C No tes addulct ethyl) sulfide 0, 9 ° C 0.00156 59 Adduct A 0.005 0.02 ^b o, 0047 0.0022 ^b 0.0014 60 ti 0.002 0.02 00473 61 It 0.002 0.05 - - 0.00254 0.00366 62 η 0.02 0.02 0, -, ■ 0.00204 —-, ■ ' 63 Adduct B 0.005 0.02 0, 00488 O 64 H 0.002 0.02 - 00475 0 _# 01044 0.0039 co
00 65 Il 0.02 0.02 0, O 66 0.05 long 0216 194 a - Tests at this temperature are 4 hours

b = mean value from 2 attempts «

Adduct A - adduct of tall oil fatty acids with epiehlorohydrin and triethyltetramine.

Adduct B = adduct of tall oil fatty acids with epichlorohydrin and tetraethylene pentamino

cn cn

1621587

A sixth set of tests is done in the same way as that fifth series of tests performed, with the exception that two Roll-sintered strips and 0.1 g CuO are added to each test solution along with clean, weighed metal corrosive strips whereupon the contents of the pressure vessel are cooled to 60 ° C and air after the 16 hour heating period is blown through. Bis (2-arainoethyl) sulfide is used in each test used at a concentration of 0.02% by weight «After completion the testing is done after rinsing, drying and weighing the Stripes no foam noted on these «The used Adducts, the test temperatures and the observed corrosion rates are summarized in Table VII.

Test use «= weight- # cleaning- corrosion rate Nrc tes adduct temp., 7 C speed _T g / cm / day

^a 0.00185

0.0016 ^a 0.0017 ^a 0.0027

67 Adduct Ä 0.02 130 68 It 0.002 69 t! 0 * 002 I30 70 it 0.002 120 71 Adduct B. 0.02 120

a = 5 average of two trials.

Adduct A = adduct of tall oil fatty acids with epichlorohydrin and Triethylenetetramine.

Adduct B "adduct of tall oil fatty acids" with epichlorohydrin and Tetraethylene pentamine.

1098 20/19 47

BATH

7th test series.

A seventh series of tests is carried out * to show the protection of steel strips when air is blown through them. In each case, an inhibited cleaning solution / the 0 * 02 weight ~ $ bis (2-aminoethyl) sulfide and one of the intralinear ethylene amine -Adducts, used to clean a roll-sintered strip at 151 ° C, the chelating agent being partly consumed by chelating dissolved iron. In 'each case two corrosion strip and a copper-clad strips of the test solution ^ added whereupon ml of the test solution over a period of JO minutes about 113 (O _9,004 cubic feet) of air is blown per minute "In any case, the strips are taken from purified * * weighed again and considered »In each case the corrosion is less than 3» 5 rag per strip, with most strips less than 1 mg «The adducts used - * · the extent of the consumption of the chelating agent as well as the test temperatures are in the range Table VIII summarized below

BATH 10 9 820/1947

Table VIII

test
No. use ι
tes adduct 0.005 % consumption
tes chelie
funds Test temp., ⁰ C 72 Adduct A Oj 002 72 60-66 73 ti 0, 002 61 60-66 74 H 0.005 74 93 75 Adduct B 0.002 71 60-66 76 11 70 60-66 Adduct A = adduct of tall oil fatty acids with
Triethylenetetramine. Epichlorohydrin Adduct B - adduct of tall oil fatty acids with
Tetraethylene pentamine. Epichlorohydrin and < 8th test series

In a further series of tests, various polycarboxylic acids, metal coraplexing agents, are used to clean three essentially identical high-pressure steam kettles to remove hardness and iron oxide blisters that are mixed with copper deposits. Each boiler is filled with a cleaning solution that is sufficient for circulation and is able to reach all critical surfaces. The amount of cleaning solution added is approximately 30 28o 1 (8000 gallons). Each solution contains approximately 10 wt .- # of the polycarboxylic acid metal sequestrant and 0.02 wt .- # bis (2-aminoethyl) sulfide. The solution used in the first kettle also contains 0.002% by weight of the adduct of tall oil fat

109820/1947

acids, epiehlorohydrin and triethylenetetramine. The solution in the first boiler contains Ä'DTE as a folycarboxylic acid complexing agent, the solution having an initial pH of 9 which is achieved by adding the required amount of ammonia is adjusted to the solution. The solution in the second kettle contains nitrilotriacetic acid, the pH being adjusted in a similar manner. the Solution in the third kettle contains citric acid, the Initial pH is 7 *

The cleaning solution in each vessel is brought to a temperature of 150 ⁰ C and l6 hours, maintained at about this temperature while being circulated through the boiler system. During this period of time, essentially all hardness and iron oxide deposits dissolve, and the copper which has been released in the deposits is deposited on the ferrous metal substrate.

Each kettle and its contents are then allowed to cool ^{to approximately 65 ° C.} The pH of the solution in the third kettle is raised to 9 by adding ammonia to the solution. Compressed air is then introduced into the solution in each kettle through a conduit * connected to an air distributor in the lower part of the kettle, with the air being withdrawn from the top of the kettle. Such blowing of air is carried out for about 35 minutes with the temperature at about

109820/1947

- ■ 27 -

65 ° C is kept «, the solution in each kettle is drawn off * whereupon each kettle is rinsed a few times with water. Add approximately 37-850 liters (10,000 gallons) of water to each rinse used. Each boiler is then opened and subjected to an inspection. It turns out that they are hot Metal surfaces are clean and shiny and substantial no pitting or other signs of corrosion can be recognized by the cleaning solution.,

- BATH

109820/1947

Claims (1)

P a te nt claims 1. An aqueous solution that is suitable for cleaning metal surfaces, characterized in that it has a pH of _$ 7 to owns and O ₅ 5 to 40 wt .- ^ of an ammonium or metal Aminpolycarfeoxylat I comp lexbildners and 0.01 to 0 ≤ 5 wt. = ^ At least one thioethylamine of the formula I. AS _x -J-CH ₂ CHRKH in which A represents hydrogen _9, a lower alkyl group or a radical of the formula II R ¹ KH (CH ₂ ) _m - II . I. , where R represents a lower alkyl group "X represents 1 or 2, typified R are each independently hydrogen or a lower alkyl group and η 1 to 8 * the hydrosulfide salt of such a compound or a thio * δ thy Larain of formula III HI CH ₂ CH ₂ ' 109820/1947 · »29 ·" in which R, independently of one another, has the meaning given above and ο stands for l _s 2 or J ^ contains ₀ 20 Aqueous solution according to claim I _3, characterized * that the thioethylamine consists of bis (2-aminoethyl) sulfide » 3 'An aqueous solution according to claim 1 or 2 _S characterized in that it additionally O * ₅ Ol 0 to 20 percent by _e »$ contains an amine-ketone-A ldehyd fatty äure adduct" 4. Process for cleaning metal surfaces, wherein the Surfaces contacted with an aqueous alkaline solution which contain a polycarboxylate metal complexing agent, after which the treated surfaces are rinsed with water v / earth, characterized ^ that a corrosive attack on the metal by the presence of at least one thioethyamine of Formula I. A-S. R I wherein A is hydrogen, a lower alkyl group or a Remainder of formula II R 'M (CH ₂ ) _m - II * where R 'denotes a lower alkyl group * X 1 or 2 R represented in each case independently of one another hydrogen or hydrogen symbolizes a lower alkyl group and η 1 to 8 or a hydrosulfide salt of such a compound _ _ 109820/1947 6AO original of a thloethylene amine of the formula III ^τττ in which R each independently of one another are those given above Has meaning and ο stands for 1, 2 or 2 «in the solution is significantly reduced " 5. The method according to claim 4, characterized * that the aqueous alkaline solution used has a pH of 7 to 10 owns. 6. The method according to claim 4 or 5 *, characterized in that that the aqueous solution used 0.01 to 0.5 wt .- # of the thioethy! amine contains. 7. The method according to claim 6 * characterized * in that the aqueous alkaline solution used contains 0.02 to O ₅ 20 Sew »» ^ of the thioethyamine. 8 »Method according to one of claims 4 to J _3, characterized in that the aqueous solution used contains bis (affainoethyl) sulfide. 9. The method according to any one of claims 4 him & _s records «that the aqueous alkaline solution used also contains 0.01 to 0.2 wt .- ^ of an amine-ketone ™ Aläehyd-F © fetsMi3re-Mdukts . 10S82Q / 1947