CS241671B1 - Cold metal lubricant - Google Patents

Abstract

The essence of the solution lies in the fact that the composition contains 70 to 95% by weight of soap based on monovalent salts of higher fatty acids, preferably sodium salts of saturated acids, and 5 to 30% by weight of a complexing agent.

Description

The present invention relates to a lubricant for cold metal forming.

Soap-based lubricants are very widespread in drawing technology and, in combination with pre-treatment of the surface of the molded material by phosphating, have their merit even during very demanding forming operations. In the so-called wet forming, the soaps are used in the form of aqueous solutions, which are degraded over time, as the impurities from previous chemical treatments are concentrated in the lubricating baths. These include mainly divalent and trivalent zinc and iron cations, which come from pre-phosphated steel and tend to form zinc, iron and iron soaps respectively. When the soap solution is prepared from industrial water, calcium and magnesium soaps are also formed. All these polyvalent fatty acid salts are very limited in water solubility and thus form a solid, ever-expanding layer in the lubricating bath, the presence of which is clearly a negative phenomenon, in particular for the following reasons:

1. the equivalent of functional soluble soaps is consumed for the formation of polyvalent soaps,

2. the presence of insoluble matter creates heterogeneity in the lubrication bath and prevents the formation of a homogeneous layer of lubricant on the metal surface,

3. Different physicochemical properties of insoluble soaps (alkalinity, melting point, surface affinity, etc.) under conditions where the satisfactory properties of the soluble soaps cause the subsequent lubrication of the lubricated film, which can lead to material destruction.

Therefore, if the content of insoluble soaps in the lubrication bath exceeds the acceptable limit, the entire content must be replaced, which is very uneconomical in the current conditions of general lack of quality soap lubricants.

The composition according to the invention contains 70 to 95 wt. % of soaps based on monovalent salts of higher fatty acids, preferably sodium salts of saturated acids and 5 to 30 wt. complexing agents based on nitrogen-containing organic acids or their salts with monovalent cations or alkoholamines or phosphates of monovalent cations or mixtures of the abovementioned types of compound.

The present invention overcomes these drawbacks and allows for up to 100% increase in the life of soap lubricating solutions. Its essence consists in adding water-soluble soaps of suitable composition to additives with the ability to hydrophilize insoluble salts on the one hand and to prevent their formation by the formation of polyvalent cations into a water-soluble form.

The graph in Fig. 1 shows the dependence of the reduction of insoluble soap formation - the y-axis on the increasing concentration - the x-axis of the mixed additive consisting of the pentasodium salt of diethylenetriaminopentaacetic acid and triethanolamine. As can be seen from the figure, 1 wt. 0.25 wt. % insoluble soaps to soluble form in a real process bath containing 5 wt. sodium stearate at iron and zinc content = 0.04 wt.

The following graph in Figure 2 documents the triethanolamine-x-axis complexation capacity for three different concentrations of sodium stearate solutions containing Fe ³⁺ and Zn ²⁺ cations. The y-axis indicates the% by weight. Fe + 4- Zn in dry matter. Above curve 1 is the area representing the insoluble soap heights for a sodium stearate concentration of 0.5% w / w; curve 2 is for a sodium stearate concentration = 1.8% by weight. and curve 3 for a concentration of 5 wt.

The invention is illustrated by the following examples.

Example 1

To 60 kg of sodium stearate is added 20 kg of pentasodium salt of diethylenetriaminopentaacetic acid. The lubrication bath is prepared by dissolving said mixture in 1000 kg of demineralized water. Compared to conventional stear baths, the lubricating bath thus prepared has a lifetime of up to 100%.

Example 2

600 kg of sodium stearate is dissolved in 11 400 l of water. 200 kg of a 40% aqueous solution of triethanolamine / dihydroxyethylglycerin sodium in a ratio of 1: 9 are added successively to the solution. The resulting lubricating bath has a very good ability to prevent sedimentation of insoluble soaps.

Example 3 kg of a blend consisting of 30 wt. % sodium laurate, 30 wt. sodium palmitate and 40% wt. sodium stearate, 5 kg of chelate II and 5 kg of sodium hexaphosphate form, after homogenization, a masterbatch which is dissolved in 1900 kg of demineralized water. The advantage of the bath thus prepared is the ability to hydrophilize the water-insoluble impurities.

Example 4 wt. % of a mixture of solid animal fats alkaline hydrolyzed with NaOH, 20% by weight nitrile triacetic acid, 5% by weight monoethanolamine and 5% by weight; a mixture of Maddrell's salt and ammonium triphosphate (1: 1 wt.) forms a feed for the preparation of an aqueous bath at 70% w / w. of active substances. Its lubricating properties correspond to those of pure, higher fatty acid salts, which can be saved in a significant amount through this process. The lubricating bath is characterized by the ability to dispose of insoluble impurities and to chelate the water-soluble Ca ²⁺ and Mg ²⁺ cations present to a soluble form.

Example 5 kg of alkaline hydrolyzed coconut oil, 60 kg of sodium stearate and 5 kg

Sodium palmitate B was mixed with 2 kg of chelatone III and 3 kg of triethanolamine. The soap thus prepared is used in a concentration of 5-8% by weight in water. In contrast to the above, it is characterized by a lower melting point and the ability to control the temperature of the lubrication bath. In this way, an optimum lubricant layer on the surface of the molded materials can be achieved depending on the required number of strokes.

Claims (2)

SUBJECT 1. A cold-forming lubricant comprising 70 to 95 wt. soaps based on monovalent salts of higher fatty acids, preferably sodium salts of saturated acids and 5 to 30 percent by weight of complexing additive. Composition according to claim 1, characterized in that the complexing additive consists of one or more of the following: nitrile acetic acid, ethylenediaminotetraacetic acid, diethylenetriaminopentaacetic acid, dihydroxyethylglycine and partially or totally neutralized sodium salts of these periodic cations. mono- to triethanolamines, phosphates, metaphosphates and polyphosphates of monovalent cations.