DE1932576C - - Google Patents

Description

N- (CH- CH ₂ - OH) ₃ _ "

in which / 1 = 0, 1 or 2, R = H or methyl radical, R '= a methyl, ethyl, propyl, isopropyl or butyl radical.

35

As is well known, to protect against freezing, alcohols or glycols are added to the water of cooling systems, preferably ethylene glycol, too. But since ethylene glycol-water mixtures are metallic materials attack a cooling system, in particular ferrous metals, must by adding other substances, so-called Inhibitors that eliminate the risk of corrosion. As inhibitors to protect door iron (cast iron and Steel) are inorganic salts such as alkali benzoates, alkali nitrites, borax, alkali nitrates, alkali carbonates, Alkali salts of aliphatic dicarboxylic acids, alkanolamines, alkali chromates or dichromates among known to others for a long time. Furthermore, it can be stated in relation to the prior art that inhibitors such as Alkali phosphates, alkali silicates or alkali zinc silicates specifically provide corrosion protection for aluminum, Benzotriazole or sodium mercaptobenzothiazole, however, reduces non-ferrous metal corrosion. It is to.' wTÜbeckon that the compounds mentioned individually are not capable of the cooling system of an automobile engine, which consists of numerous materials or to effectively protect other cooling equipment. So you already have combinations of the known inhibitors are used, but a combination of such protective substances must be of a variety of requirements at the same time. Mixtures of inhibitors often show disadvantages, than the protection of one or some types of metal is improved, but that of other types of metal is worsened again. Above all, the adequate common protection of iron that is required today and aluminum has not yet been solved satisfactorily.

Many car manufacturers today use one Antifreeze required that apart from an extremely high level of corrosion protection in a cooler system The very different metals that are present also have as high an alkali reserve as possible in order to achieve a To be able to leave radiator antifreeze in the cooling circuit for years to come. Besides that Antifreeze agents must not produce any precipitates with the hardness components of the water, if possible none Do not attack foam strips or plastic sealing elements. Finally can too the economic viability of an inhibitor combination should not be disregarded.

It has now been found that an antifreeze agent for door cooling systems, in particular for internal combustion engines, based on 1,2-glycols is advantageous The hardness components of the water are wise high reserve alkalinity, insensitivity. Foam free ~ and excellent anti-corrosion properties, if it contains:

1.50 to 5.00 percent by weight of alkali metal benzoate, preferably Na benzoate.

1.00 to 2.50 percent by weight sodium tetraborate decahydrate,

0.10 to 0.50 percent by weight alkali nitrite, preferably sodium nitrite,

0.02 to 0.10 percent by weight benzotriazole or Mercaptobenzothiazole or mixtures thereof.

0.02 to 0.15 weight percent sodium metasilicate and

0.10 to 1.00 percent by weight of a water-soluble tertiary amine of the formula

N- (CH-CH ₂ -OH) ₃ _ "
Ri

in which / 1 = 0, 1 or 2, R = H or methyl radical. R '= a methyl, ethyl, propyl, isopropyl or Means butyl radical. The percentages by weight relate to the total mixture.

The reserve alkalinity in the mixture according to the invention can be determined by varying the components Adjust sodium tetraborate decahydrate and tertiary amine without the corrosion protection deteriorating. This makes it possible to bring the alkalinity to a value of 10 to 25 and thus a long-term effect against the occurrence of acidic oxidation products of ethylene glycol in the cooler system and to prevent the ingress of acidic combustion gases into the cooler circuit.

The individual inhibitor components of the antifreeze agent according to the invention are known. combination : n of alkali benzoate and sodium nitrite are in British Standard BS 3151, combinations from sodium benzoate, sodium nitrite and sodium tetraborate decahydrate in the German Auslegeschrift 1 108 985. Mixtures of sodium nitrite. Sodium nitrate, boric acid and / or borax, Sodium carbonate, sodium silicate and mercaptobenzothiazole are from U.S. Patent No. 2,815,328 known. In the German publications 1 154 976. 1 201 121, I 226 366 and I 287 895 are further combinations of known inhibitors listed. This

However, combinations / have the disadvantage that they have only a low reserve alkalinity or a Increase of this value from the optimal corrosion protection behavior leads. In addition, these combinations often tend to form fills with hard water, especially when adding N'a carbonate. A heat exchange medium "after the German Auslegeschrirt 1 125 407 with the inhibitors Sodium benzoate. Sodium nitrite and aliphatic! Amine in no way meets today's requirements with regard to corrosion protection, in particular on aluminum and non-ferrous metals.

The following examples are intended to explain the present invention and its advantages in more detail.

B e i s ρ i e I I

The corrosion behavior of antifreeze was determined according to ASTM D 13S4-65 and given the losses in g in ^2, wherein a mixture of i spezilikationsgemäß volume part inhibited Glvkol and 2 parts by volume of water with an impurity ion content of 148 mg 1 Na-sulfate. 165 mg of sodium chloride and 138 mg of sodium bicarbonate are used.

The mixtures were tested comparatively:

Table I.

1 Ethylene glycol 97.5 Na tetraborate decahvdrat 2.5 Na benzoate - Na nitrite Na nitrate Na carbonate Na metasilicate pentahydra * - Benzotriazole - Na-Mercap'obenzo- thiazole - Phthalimide Triethanolamine - N-methylmorpholine - water -

Mixtures

2 3 4th 93.95 95.05 96.70 0.85
4.60
0.60 4.60
0.20 2.50
0.50 - 0.05
0.10 - I I I - 0.30

5 6th 95.00 92.75 1.00 2.00 2.25 4.00 0.35 0.50 0.30 0.50 - 0.10 0.03 0.10 0.07 0.05

94.89 j 95.14 0.75 0.75

0.71
0.05

0.05
0.25

3.30

0.71 0.05

0.05 3.30

9 10 5.58 97.11 1.00 2.50 2.50 - 0.60 0.07 - 0.06 0.15 0.15 0.07 0.06 0.05 - - 0.05 0.05 -

Test results according to ASTM D 1384-65 (corrosion behavior)

copper

Solder on brass

Brass

steel

Cast iron

aluminum

3.8 1.5 1.0 5.3 0.5 0.9 2.0 1.8 0.2 13.2 0.9 0.4 10.8 0.4 3.8 0.4 3.9 0.6 4.6 1.8 1.6 2.4 0.5 1.6 1.8 1.8 0.0 4.1 0.1 0.3 0.4 0.6 0.3 1.0 0.8 0.4 42.4 0.3 0.4 0.4 0.4 0.1 5.8 0.7 0.3 12.8 4.5 4.8 13.5 1.1 1.9 6.5 9.5 0.6 14.6 8.6 28.5 3.5 9.0 18.0 18.5 18.5 12.5

0.5 1.8 0.3 1.2 1.0 4.5 18.5

These mixtures represent the prior art referred to above in the following way:

Table II

Mixture 1: VTL 68 050-005.

Specification BS 3152

Mixture 2: German exposition

Mixture 3: merchandise

Mixture 4: German copy

Mixture 5: German interpretation

Mixture 6: German commentary

Mix 7: German copy

Mixture 8: German Auslcgeschrift

Mixture 9: German copy

108 985

125 407 154 976 154 976 226 366 226 366 201 121

fiO

Mixture 10: U.S. Patent 2,815,328r, _5th

These combinations were compared with the mixtures according to the invention

Glycol

Borax + 10 water.

Na benzoate

Na nitrite

Na metasilicate

pentahydrate

Benzotriazole

Triethanolamine. . . .
Triisopropanojamine
water

Mixtures Il 12th 94.40 94.12 1.40 • 1.40 2.50 2.50 0.25 0.25 0.10 O.OS 0.05 0.05 0.30 0.60 1.00 1.00

94.20 1.40 2.50 0.20

0.05 0.05 0.80

I nn

continuation

L.

Mixtures

11 I 12 I.

Test results according to ASTM D 1384 (corrosion behavior)

-65

copper

Solder on brass

Brass

steel

Cast iron

aluminum

Reserve alkalinity

0.03 0.01 0.10 0.10 0.U 0.13 13.00

0.03 0.03 0.12 0.08 0.10 0.23 15.00

0.10 0.10 0.08 0.10 0.10 0.20 21.00

The comparison of Table I with Table II shows that the corrosion losses in the mixtures according to the invention are considerably lower than with known inhibitor combinations. It is also possible to use the formulations according to the invention to give a high reserve alkalinity (for long-term effects) (by adding amine). without any Deterioration of the anti-corrosion effect occurs. All inhibitor combinations after the

ίο state-of-the-art technology with high reserve alkalinity but a relatively high attack on aluminum and mostly also on soft solder. So the formulations according to the invention show clear synergistic effects.

The inhibitor combinations 2. 3. 4. 5. 6. 9. 10 and Examples 11 and 12 according to the invention were tested in the so-called EMPA test according to »Schweizer Archive for Applied Science and Technology «. 22. pp. 65 to 74. 1956, elaborated. This results in the following weight losses in ^ irr:

Table III

3 Mixtures 4th 5 6th 0.6 State of the art 0.5 0.6 0.4 2 0.5 0.8 0.5 0.3 0.3 0.3 2.3 0.6 0.5 0.5 1.2 5.8 0.5 2.6 1.8 3.2 8.5 0.8 1.6 1.7 1.9 9.8 0.4 1.7 1.6 0.5

according to the invention
11 12

steel

Cast iron

Brass

Soft solder

Aluminum (Avional) ....
Aluminum (SiIafont-2) ...

The experiments were carried out with artificial lime water 20 ° d. II. According to the German interpretation document 1 154 976 accomplished. Here, too, one recognizes a superiority of the mixtures according to the invention.

Example 3

Motorenicst General Motors Corp. 1899-M (Simulated Service Test)

To check the resistance of the inhibitor, a simulated 6-week engine test according to GM-1899-M was carried out. The essential parts of the test apparatus are a standard cooler, an aluminum water pump and an aluminum reservoir. The pump is operated by an electric motor at 2500 rpm. A thermostat keeps the coolant at the desired temperature 0.4
0.3
0.3
1.9
0.1
0.6

0.5
0.4
0.2
2.3
1.9
1.7

0.3
0.1
0.3
0.1
0.0
0.0

0.2
0.1
0.2
0.2
0.0
0.2

from 80 to 82 ° C. The coolant flows from the aluminum pot directly to the radiator head. A mixture of 25 percent by volume of anti-freeze glycol and 75 percent by volume of synthetic water, 0.165 g of sodium chloride and 0.275 g of sodium bicarbonate, is used. Contains 0.444 g Na sulfate and 0.00265 g Cu chloride per liter of water. 3 metal test sets are installed in the aluminum water pot, which remain in the flowing coolant for the entire duration of the test of 6 weeks, which corresponds to around 97,000 kilometers. The closed system is opened once a day. After the test, the appearance of the aluminum water pump is assessed and the weight loss of the metal strips after cleaning according to the ASTM method in g / m ^{2 is} determined. Engine tests were carried out with the following 4 mixtures:

Table IV

Copper ...
Soft solder ..
Brass ..

steel

Cast iron.
aluminum

Mixtures

Stand de r technology 9 11th according to the invention ! 2 4th 1.5 0.2 0.3 5.8 4.0 0.15 0.2 18.0 1.3 0.1 0.2 6.9 1.0 0.1 0.5 0.8 1.2 0.9 0.8 0.4 13.0 3 5 28.0

Assessment of the aluminum water pump

I'Orlsct / ung

Mixtures

Slaml of technology 4 I <)

slight erosion and pitting on the inside of the aluminum housing

invent iingsgcmäU

slight tarnish, otherwise unchanged

This test also shows the superiority of the mixtures according to the invention over those of the prior art the technology, as can be seen from the comparison of the weight losses, especially with aluminum and soft solder, and also clearly evident from the appearance of the aluminum water pump.

309614/334

Claims (1)

Claim: antifreeze for cooling systems .e. in particular of internal combustion engines, based on 1.2 glycols and corrosion inhibitors, characterized by a content of 1.50 to 5.00 weight percent alkali benzoate. preferably sodium benzoate. 1.00 to 2.50 percent by weight sodium tetraborate decahydrate, 0.10 to 0.50 percent by weight alkali nitrite, preferably sodium nitrite. 0.02 to 0.10 percent by weight benzotriazole or mercaptobenzothiazole or their mixtures, 0.02 to 0.15 percent by weight sodium metasilicate, 0.10 to 1.00 weight percent of a water-soluble tertiary amine of the formula