CH618464A5 - Corrosion-inhibiting aqueous solution for lubricating and cooling workpieces made of metals and plastics during machining and for washing the machined workpieces - Google Patents

Description

The invention relates to a corrosion-inhibiting aqueous solution according to the preamble of patent claim 1.

Known corrosion-inhibiting cooling lubricants for machining are either mineral oil-containing products with very different oil contents from 20 to 75% (based on the concentrate) or salt solutions with 10

up to 40% admixtures of nitrite, polyalcohols and amines.

The substances stabilizing the emulsion of the known mineral oil-containing cooling lubricants (emulsifiers) are destroyed 5 quite quickly by the common manner of chemical and bacteriological processes. The result is a separation of the oil component from the water. This results in rust on the machined workpieces. Other accompanying circumstances are bad smells, combined with a discoloration of the cooling lubricant due to iron sulfide. Some of these processes occur after just a few weeks and must therefore be suppressed by constant monitoring and the addition of emulsifiers and preservatives.

15 While monitoring for bacteria, fungal and yeast infestation can still be carried out to some extent economically in larger central cooling lubricant systems, this is usually no longer the case for machines with individual supply. The service life here is often very short, and the costs 20, including the removal of the cooling lubricant, are extremely high in relation to the service life.

Practice has shown that the destruction of the emulsifiers and the associated instability of the cooling lubricants is initiated by oxidation processes of the metal chips introduced. The oxidation promotes the growth of the microbes, which in turn accelerate the destruction.

It is therefore an object of the invention to develop a corrosion-inhibiting solution for machined workpieces, which resists the attack of bacteria and thus achieves a long service life. It is intended to provide sustainable protection against corrosion, act as a lubricant between the tool and the material to be machined, and have a sufficiently high thermal conductivity. 35 The object is achieved by the invention described in claim 1.

The antioxidant in the form of the triethanolamine salt of para-tertio-butylbenzoic acid is able to trap the peroxidic radicals formed during the oxidation and to suppress a chain reaction which may result from autoxidation.

The proportion of triethanolamine para-tertio-butyl benzoate acts as an anti-corrosion agent. It is created by neutralizing the para-tertio-butylbenzoic acid with alkanolamine. Combination with disodium tetraborate (Borax) and a fatty acid alkanolamide gives an inhibitor which

1. makes the cooling lubricant durable,

so 2. protects the metal against the oxygen dissolved in the water,

3. A protective film with sustainable on the metal surface

Forms corrosion protection, and

4. does not allow any electrochemical interface potentials. 55 The demand for sufficient derivation of the at

Editing heat is created by the proportion of water with its high spec. Warmth fulfilled. Various soaps are used as lubricants, which are produced as follows:

60 Coconut palm kernel soap is produced separately as soda soap, while olein is neutralized wildly with alkanolamine to alkanolamine oleate. The mixture of these different soaps has a friction-reducing and foam-regulating effect.

65 To avoid foaming in strong turbulence and at high concentrations, an ethylene oxide-propylene oxide polyaddition product is added as an additional foam brake.

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3rd

618464

The pH settings are made with 50% sodium hydroxide solution so that the finished concentrate has a pH of 8.0-8.5 to avoid attacking the skin even at high concentrations.

The para-tertiary butylbenzoic acid is neutralized at 80 ° C with triethanolamine (pH 8).

The fatty acid alkanolamide which acts as an inhibitor in the solution according to the invention, and the soaps which serve as lubricants, are wash-active substances in terms of their structure. It is therefore a further feature of the invention that the solution specified in claims 1 to 3 can also be used as a detergent for the machined workpieces. Because of the high washing power of the soaps present and their reduced foaming power, the solution according to the invention can be used, for example, in a concentration of 1% by weight at 60 ° C.-80 ° C. in spray washing machines for metals. After drying, the parts have long-term corrosion protection thanks to the antioxidant.

Depending on the washing temperature, concentrations of 0.5 to 1.5% by weight of the solution can be used.

In order to ensure adequate protection against corrosion of the workpieces stored wet after machining, the cooling lubricant according to the invention is produced in a concentration of the solution of 2 to 10% by weight in water.

The percentage compositions of the mixture of substances indicated in patent claim 2 represent embodiments of the invention. The preferred values indicated according to claim 3 result in optimal corrosion protection of the materials and minimal frictional wear of the cutting tools when used in the concentrations provided according to claim 4.

A 5% solution of the mixture emulsifies about 1% mineral oil. The mineral oil can be easily separated in ultrafiltration systems. The permeate can be reused.

The advantages which can be achieved by the invention compared to the prior art are summarized as follows:

1. Long service life.

2. No, or only small additions of bactericides and fungicides.

3. Good and sustainable corrosion protection from 2% -

solution for steel and from 3% solution for gray cast iron.

4. Low maintenance, control of the concentration with the hand refractometer is sufficient.

5 5. No special mixing equipment required for mixing.

6. No toxic substances.

7. Good skin tolerance.

8. An emulsified foreign oil content about 1%. This means that much less oil is generated when separating than with oil-in-water

Emulsions.

9. Simplified warehousing and waste water treatment by using the same agent for washing and processing.

15 10. No oil mist with heavy cutting.

11. Even during long breaks in operation, neither air flotation nor circulation is required.

12. No contamination and clogging of cooling lubricant lines.

20 13. No chemical attacks on valves and pumps.

14. No use of additives, e.g. Chlorinated paraffins, which form reaction products that are aggressive to the skin.

15. Simple separation of the mineral oil content in ultrafiltration systems.

25 16. Reuse of the permeate as a detergent and, after adding concentrate, also as a cooling lubricant.

The service life of the solution when used as a cooling lubricant is 3 to 4 times as long as that of the commercially available oil-30-in-water substances. The latter require weekly additions of bactericides and fungicides as well as laboratory monitoring. As a result of the considerably longer service life of the new solution, the amounts to be discarded and treated with wastewater are reduced to% to% of the 35 previous amounts of liquid. This is of the greatest environmental importance.

Since the cooling lubricant according to the invention can also be used as a detergent in the washing machines, only a single agent needs to be processed and the 40 preparation systems can be optimally aligned to this agent.

The usual use of various washing and cooling lubricants creates considerable additional costs and difficulties in wastewater treatment.

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Claims (4)

618464 1. Corrosion-inhibiting aqueous solution for lubricating and cooling workpieces made of metals and plastics during machining and for washing the machined workpieces, characterized in that they contain triethanolamine-para-tertiary-butylbenzoate, fatty acid alkanolamides, borax, an ethylene oxide propylene oxide Contains poly addition product, triethanolamine oleate and coconut palm kernel soap. 2.6 7.8 6.0 2.0 19.8 Triethanolamine para tertiary butyl benzoate borax Fatty acid alkanolamide Ethylene oxide propylene oxide poly addition product Olein Triethanolamine Coconut palm kernel soap Fragrance oil Water. 2-3 6-9 4-6 2 and 10-30 borax Fatty acid alkanolamides Ethylene oxide propylene oxide polyaddition product Olein Triethanolamine Coconut palm kernel soap Fragrance oil water 2. A process for the preparation of the corrosion-inhibiting aqueous solution according to claim 1 with a density of 1.06 at 20 ° C and a viscosity of 350 cSt at 20 ° C, characterized in that the components mentioned below are mixed in the proportions given: 22-30 percent by weight triethanolamine-para-tertiary Butyl benzoate 2nd PATENT CLAIMS 3.3 »20.8» 10.4 » 3. The method according to claim 2, characterized in that the components mentioned below are mixed in the stated proportions: 22.3 percent by weight 3-5 20-25 9-11 4. Use of the solution according to claim 1, characterized in that it serves as a cooling lubricant in a dilution of 2 to 10% by weight and as a detergent in a dilution of 0.5 to 1.5% by weight.