DD218635B1 - COOL-OR. HEAT TRANSFER AGENTS WITH CORROSION- AND CAVITATION-PREVENTIVE INHIBITOR SYSTEM - Google Patents

Description

Field of application of the invention

The invention relates to an additive of synergistically acting inhibitors for cooling or heat transfer agent on an aqueous and / or glycol-based basis for cooling or heat transfer systems such as cooling system for internal combustion engines, air conditioning, heat exchangers, the optimal corrosion protection in systems consisting of light, heavy - or non-ferrous metals or combinations of these materials, guaranteed.

Characteristic of the known technical solution

To avoid corrosion processes in aqueous and / or glycol-containing cooling or heat transfer systems, which consist of metallic materials, and by decomposition products, ingredients of the heat transfer medium or by entering the system foreign components such. As oxygen, carbon dioxide or caused by dissolving metal ions are z.Z. common corrosion inhibiting additives such as amines, phosphates, chromates, phosphonates, silicates, nitrites, borates, nitro compounds, polycarboxylic acids and others are used.

Although good anti-corrosive effects could be achieved in special applications in such systems, satisfactory protective values are not achieved, especially where sensitive materials or electrochemically unfavorably combined material combinations are to be found.

The same applies to where on highly effective additives such. As nitrite and chromate from toxicological, carcinogenic or ecological aspects must be waived.

US Pat. No. 2,194,491 describes the use of a corrosion inhibitor system of sodium cappedobenthiazole and a water soluble salt of phosphorous acid. Such a corrosion protection system results in aqueous solutions containing hardness components, unwanted precipitation, which in turn cause erosion corrosion.

The known corrosion inhibitor causes strong corrosion on non-ferrous metals, in particular on aluminum and lead alloys.

In the DD-WP 21295 and DE-OS 2841908 is also based on the already mentioned combination of phosphate, triethanolamine and mercaptobenzothiazole. These components exhibit the same behavior as the inhibitor package described in US Pat. No. 2,194,491.

The sole addition of mercaptobenzothiazole or its alkali metal salts, as recommended in DE-AS 1226366, exerts a positive influence on copper, but does not prevent aluminum, tin and lead alloys from being attacked.

The use of carboxylic acid in combination with gluconic acid or tartaric acid and Diäthanoi- or monoethanolamine for aqueous treatment liquids for the corrosion protection of metal surfaces is proposed in DE-OS 2613234.

Such combinations of the carboxylic acid show in glycol-containing heat transfer systems, as used in the cooling system in internal combustion engines, which consist of a variety of metals and metal alloys, use, a sufficient protective effect.

Steel and cast iron are protected. The attack on tin, lead and special aluminum alloys is above the permissible removal rates.

A composition of a cryoprotectant according to H. H. Collin from benzoate, borax and nitrite, discussed by F. W. Hirth and H. Packhard (Literatur zur Werkstofftechnik, 8,321-327,1977) also does not bring the desired positive influences.

The corrosion on aluminum is partially restricted, but the attack on gray cast iron is intensified.

With the hitherto offered inhibitors, it is not possible to effectively protect the overall metal pallet of materials against corrosion and cavitation of the medium used.

Object of the invention

The aim of the invention is an additive for cooling or heat transfer agent on an aqueous and / or glycol-based basis with improved protective properties against light, heavy or non-ferrous metals or combinations of these metals in Kühlbzw. Heat transfer systems, which is characterized over conventional products by a high protective effect in the applications mentioned and is multifunctional compared to the previous means.

Essence of the invention

The object of the invention is to provide an additive for cooling or heat transfer agent for aqueous and / or glycol-containing media, which contains no carcinogenic and eutrophic substances and ensures optimum corrosion protection against the materials used.

Surprisingly, it has been found that the reaction product of carboxymethylcellulose with mercaptobenzothiazole and 2-ethylhexanoic acid in cooling or heat transfer systems exerts very good corrosion protection.

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It has also surprisingly been found that these compounds prove to be particularly stable with the usual inhibitors and cause a further synergism with these components.

While no or stimulating influences were determined when using the basic components on which the invention is based, which can be interpreted as follows:

- carboxymethylcellulose - behaves indifferent to all feedstock and material combinations

Mercaptobenzothiazole exerts a limited effect on non-ferrous metals, but a copper deposition and thus

does not prevent increased corrosion on aluminum,

- 2-ethylhexanoic acid - causes corrosive attack mainly in lead and tin alloys,

Surprisingly, the reaction product gave very good corrosion and cavitation protection. This effect is due to the rearrangement of the functional groups of the starting materials, as shown in the examples

These properties of the reaction product are achieved when the reaction is carried out in accordance with the following process steps:

• Submission of a concentrated aqueous-alkaline carboxymethyl cellulose solution

• Addition of mercaptobenzothiazole with stirring in the temperature range from 50 to 65 ⁰ C.

• Slow addition of 2-ethylhexanoic acid after several hours of reaction.

This reaction of the basic components is the basis for the multifunctional action and leads to the composition of the inhibitor packages, as shown in more detail in the embodiments 1-3.

embodiments carboxymethylcellulose 10 ppm Example 1: mercaptobenzothiazole 10 ppm 2-ethylhexanoic 10 ppm hardness stabilizer 20 ppm water rest carboxymethylcellulose 0.02% Example 2: mercaptobenzothiazole 0.07% 2-ethylhexanoic 1.00% borax 2.00% sodium benzoate 1.10% sodium nitrite 0.50% glycol rest carboxymethylcellulose 0.10% Example 3: mercaptobenzothiazole 0.40% 2-ethylhexanoic 1.00% borax 1.50% sodium benzoate 1.00% nitrobenzoate 0.75% silicate 0.25% glycol rest

Korrosionsprüfergebnisse

The Korrion tests were performed on a modified ASTM D 1384 (336h to 88 ° C). The deposits are given in g / m ² 14d.

Example Pattern It. Pattern according to Collin Inventive. example

Metal DD-PW 21295 (glycol content) 1 2 3

copper 4.6 2.7 0.2 0.1 0.1 solder 3.4 12.0 0.4 0.2 0.1 Brass 4.2 3.2 0.3 0.1 0.2 stole 22.4 0.1 0.9 0.0 0.0 cast iron 26.1 0.8 0.8 0.0 0.0 AISiCu-Legg. 7.3 7.4 0.3 0.0 0.0 Aimu-Legg. 6.7 6.3 0.0 0.2 0.1

Annotation:·

Pattern according to DD-PS 21295 and Example 1 pattern according to Collin and Example 2 and 3

was undiluted

used

was in proportion

Antifreeze additive

Water = 1: 2 used

From the table it can be seen that the reaction product in comparison to the hitherto available for special applications inhibitors exerts a multifunctional effect even with different material combinations.

Claims (2)

-1- 203 635 Invention claim: Additive for cooling or heat transfer agent on an aqueous and / or glycol-based basis with a content of conventional anti-corrosive substances for use in cooling and heat transfer systems, which consist of light, heavy or non-ferrous metals or combinations of these materials, characterized that an inhibitor consisting of carboxymethyl cellulose, which partially with mercaptobenzothiazole and 2-ethylhexanoic acid in the mass ratio 1: 1: 1 to 1: 5: 50 was reacted, in a concentration of 0.001 to 3.5% is used.