WO1998014538A1

WO1998014538A1 - Lubricant with phospholipid and a basic compound base

Info

Publication number: WO1998014538A1
Application number: PCT/BE1996/000105
Authority: WO
Inventors: Dirk Loderer; Rudi Vanloocke; François MARLIER; Christophe Callens
Original assignee: Klüber Lubrication Benelux
Priority date: 1996-10-03
Filing date: 1996-10-03
Publication date: 1998-04-09
Also published as: ES2155203T3; DE69611553T2; EP0946691B1; DE69611553D1; EP0946691A1; AU7122396A

Abstract

The invention concerns a lubricating composition, in particular for swaging, consisting of a suspension in water of a mixture of phospholipids and an organic or mineral basic compound. For example, the composition contains 80 wt.% water, 10 wt.% phospholipids brought in the form of soja bean lecithin, and 10 wt.% of calcium hydroxide or stearylamine as basic compound. Among other advantages the lubricant can be eliminated by means of an aqueous solvent, and is easily biodegradable.

Description

LUBRICANT BASED ON PHOSPHOLIPID AND A BASIC COMPOUND The present invention relates to a lubricant. More particularly, it relates to a lubricant useful in the work of deformation of metals, such as stamping and forging. In this type of application, the lubricant is used to facilitate the deformation work, by reducing the friction forces between punch, metal and matrix.

Currently, oleaginous compounds are used as a lubricant. These pose environmental problems, in particular insofar as they are not readily biodegradable, and where it is necessary to use solvents to degrease the metal after deformation.

According to the invention, it is proposed to provide a non-oleaginous lubricant, based on phospholipid and a basic organic or inorganic compound, suspended in water.

Phospholipids are polar compounds, the molecule of which has a lipophilic fraction and a hydrophilic fraction. They are not soluble, but dispersible in water.

By organic basic compound is meant here the amines and their derivatives.

By basic mineral compound is meant a base of a metal from group IJa of the periodic table of the elements. Among other advantages, the lubricant of the invention can be removed from the stamped metal using an aqueous solvent, thanks to its hydrophilic fractions. It is also easily biodegradable, so that it poses no environmental problems. As a source of phospholipid, the inventors are particularly interested in lecithins, and more particularly in soy lecithin. The invention will therefore be described in the following with reference to the latter, but it is however not limited to this type of product, and other similar phospholipids will also be suitable. An object of the invention is therefore to provide a lubricating composition consisting of a suspension in water of a mixture of phospholipids and a basic mineral or organic compound. According to another characteristic of the invention, the composition consists, based on the total weight of the composition, of:

- 5 to 40% by weight of phospholipids

- 5 to 40% by weight of the basic compound - 90 to 20% by weight of water.

According to other characteristics of the invention, the phospholipids are present in the form of lecithin; lecithin is soy lecithin; the basic compound is at least partially in suspension; the basic compound is an amine or an amine derivative; the basic compound is a hydroxide of a metal from group lia of the periodic table of the elements; the composition further comprises an acid, to neutralize the alkalinity of the basic compound after its interaction with the phospholipids. Other aspects, characteristics and advantages of the invention will emerge from the description which follows.

Crude soy lecithin is a mixture of approximately 60% by weight of polar lipids (insoluble in acetone) consisting essentially of phospholipids, and approximately 40% by weight of non-polar lipids (soluble in acetone) consisting oil, free fatty acids and sterols.

The lecithin phospholipids are glycerophospholipids of general formula H ₂ C - O - X

Y - 0 - CH

H ₂ C - O - P - 0 - Z

IQJ wherein X and Y each independently represent an acyl radical of palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid and the like; Y represents hydrogen, and X an acyl radical as above; Z represents choline, ethanolamine, inositol or hydrogen.

Currently, lecithins are mainly used for their emulsifying properties (due to the presence of hydrophilic fractions and lipophilic fractions), for example in lubricants and in the food industry, and also as a base for ointments.

Lecithin alone, suspended in water, has little or no lubricating properties. Surprisingly, the inventors have now discovered that the addition of a basic organic compound (amine or derivative) or mineral (metal of group lia of the periodic table of the elements) to lecithin in aqueous suspension greatly improves the lubricating properties of the composition, as will be seen below.

The action or the synergistic effect of the basic compound on phospholipids is not understood to date, and the inventors do not wish to be limited to any particular theory on this subject. The presence of the basic compound makes the pH of the lubricating composition alkaline, and it may be useful to add an acid to neutralize the composition. This acid has no other function than neutralization, and will therefore generally be arbitrary, provided that it has no undesirable side effects. Without being limited thereto, it is thus possible to use H ₂ S0 ₄ , H ₃ P0 ₄ , CH ₃ -CH ₂ OH, CHOOH, and the like.

In this regard, however, it is important to emphasize that any neutralizing acid must be added to the lubricant composition, that is to say after suspending the mixture of phospholipids and basic compound, and not to the compound basic alone, before incorporation into the composition. The inventors have indeed noticed that, if the acid is added to the basic compound before the latter is added to the phospholipids in suspension, the lubricating effect is not achieved. Consequently, between the phospholipids and the basic compound, an interaction or a reaction which is not obtained with the corresponding salt or ester does occur. Thus, calcium stearate is for example known as a thickener for oil, but does not bring any synergistic effect with the phospholipids according to the invention. Likewise, a composition based on calcium carbonate or tricalcium phosphate salts does not provide effective lubrication. This is to be compared with a composition according to the invention, containing calcium hydroxide, which retains its lubricating properties even after neutralization, as will be seen below.

Preferably, the lecithin used in the lubricant of the invention is defatted lecithin, to facilitate the suspension in water. It can also be modified lecithin, for example to improve its hydrophilic properties, and therefore its dispersibility in aqueous and polar media. Thus, hydroxylated, hydrolyzed, acetylated lecithin or the like can be used. The modified lecithin may or may not also be defatted.

The proportion phospholipids / basic compound is an important parameter of the invention, insofar as there is a synergy between the two components, and where the lubricating effect is absent below a certain proportion of basic compound. On the other hand, there is no longer any significant improvement in the lubricating properties of the composition beyond a substantially equal proportion of phospholipids and of basic compound, so that there is no point in increasing the amount of basic compound substantially beyond this proportion since, in particular in the case of a basic mineral compound, this increases the amount of residues on the stamping tools, which can in the long run pose problems of clogging of the tool.

Water on the other hand only has a dilution effect, and does not change the lubrication properties, so that the amount of water is not an important parameter of the invention. The amount of water should simply be chosen depending on the desired fluidity, and therefore on the applicability of the lubricant to metal surfaces. Thus, when the amount of water becomes low, for example of the order of 20% by weight of the total composition, the composition becomes very pasty, and difficult to apply; on the other hand, when the amount of water becomes too large, for example of the order of 90% by weight of the total composition, the lubricant becomes too dilute, and there is no longer enough "active" component of phospholipids / basic compound for lubrication. The amount of water will therefore be adapted each time according to the needs and the method of application (spraying, spraying, brushing, and the like). In practice, the lubricant compositions of the invention will also contain conventional adjuvants, such as antioxidants, anticorrosion agents, and the like.

The invention will now be described in more detail in connection with specific examples of the use of phospholipid-based compositions in a drawing test.

In all the examples used as a stamping press a machine of brand R + K type A 15, supplying a maximum pressure of 15 tonnes, manufactured by the firm Roell Amsler.

The test pieces used for the stamping test were test pieces made up of discs 70 mm in diameter and 0.8 mm thick, made of 304 stainless steel. The lecithin used in the examples is defatted soy lecithin, containing at minus 97% by weight of polar lipids, marketed under the name LIPOPUR by the company Lucas Meyer.

The test consists of forming, using the stamping press, cylinders with a diameter of 35 mm and a depth of about 32 mm (the depth varies with the quality of the lubricant).

In all the .; tests, the holding force of the test piece (force exerted on the blank holder holding the test piece) is 5000 kg (PM = 5000).

Example 1 (reference) - Deep drawing using a known oil-based lubricant

A test piece is stamped using a conventional lubricant based on mineral oil, of high efficiency, commercially available from Kluber Lubrication under the name Presspate SEM 95/800. The result of a test carried out on 304 stainless steel is presented in FIG. 1, in the form of a force / displacement diagram, presenting the force acting on the punch as a function of its displacement, and therefore of the depth of the stamping. . Example 2 (comparison) - Use of lecithin alone

In this example, the conventional lubricant is replaced by a lubricant consisting of 20% by weight of soy lecithin and 80% by weight of water.

The result of the test on a 304 stainless steel test piece is shown in Figure 2.

As can be seen in the diagram, the test fails by breaking the metal.

Example 3 (comparison) - Use of a mineral base alone In this example, the conventional lubricant is replaced by a lubricant consisting of 20% by weight of calcium hydroxide and 80% by weight of water.

The result of the test on a 304 stainless steel test piece is shown in Figure 3. As can be seen in the diagram, the test fails by breaking the metal. Example 4 (invention) - Use of lecithin + base mineral

In this example, the conventional lubricant is replaced by a lubricant according to the invention, consisting of 10% by weight of soy lecithin, and 10% by weight of calcium hydroxide in 80% by weight of water

The result of the test on a 304 stainless steel test piece is shown in Figure 4.

As can be seen by comparing the diagram in FIG. 4 and that in FIG. 1, this lubricant is shown to be superior to the conventional lubricant, since the force required for stamping is significantly less than in the case of FIG. 1.

Example 5 (invention) - Use of lecithin + organic base In this example, the conventional lubricant is replaced by a lubricant according to the invention, consisting of 10% by weight of soy lecithin, 10% by weight of stearylamine (a stearylamine put on the market by the company Hoechst, under the trade name Genamin SH 100 and 80% by weight of water.

The result of the test on a 304 stainless steel test piece is presented in Figure 5.

As can be seen by comparing the diagram in FIG. 4 and that in FIG. 1, this lubricant is shown to be substantially equal to the conventional lubricant, since the force required for stamping is equal to that required in the case of FIG. 1 Example 6 (invention) - neutralization

In this example, we want to show the effect of neutralizing the composition.

The diagram in FIG. 6 shows the result of a test carried out on a composition according to example 4, neutralized to pH 8 with phosphoric acid.

The diagram in FIG. 7 shows the result of a test carried out on a composition according to Example 5, neutralized to pH 8 with phosphoric acid.

As these diagrams show, the effectiveness of the lubricating composition is practically unchanged by neutralization. Example 7 (comparison)

The purpose of this example is to show the effect of neutralization of the basic compound before formation of the composition.

In this example, calcium pyrophosphate Ca ₃ (P0 ₄ ) ₂ is mixed at 10% by weight with 10% by weight of lecithin and 80% by weight of water, to obtain a composition consisting of the same elements as that of l Example 6, but with salt instead of hydroxide.

As can be seen from the diagram in Figure 8, the test is negative since the test piece ruptures. This while calcium pyrophosphate is a known solid lubricant, among other things in stamping.

This therefore demonstrates that it is essential to first interact the basic compound and the lecithin, before neutralization, the salt or the corresponding ester which does not provide with lecithin - or more generally phospholipids - the synergistic effect of the invention.

As can be seen from the examples, lecithin alone (example 2), and calcium hydroxide alone (example 3) are not useful as a drawing lubricant, at 20% by weight in water, while the combination according to the invention (Example 4) of lecithin and calcium hydroxide in the same proportions (20%) gives a lubricant superior to the conventional lubricant, since it requires less drawing force, and therefore requires less metal.

As will be understood, there is no well-defined threshold for the lower limit of the concentration of phospholipids and basic compound. However, at a concentration of around 5% by weight of each component, the result of the stamping test becomes random, sometimes being a success and sometimes a failure.

Once the minimum concentration is reached, the effect lubricant is substantially independent of the concentration of phospholipid and basic components, as shown in the diagrams of Figures 9 and 10, relating to tests in which the proportion of the basic compound, namely calcium hydroxide and stearylamine, respectively, has increased to 20%.

As indicated in the introduction, the limit here is that imposed by the fluidity and the applicability of the composition. The basic compound to be used according to the invention will generally be commercially available in the form of a dry powder. The particle size of the powder is not in itself a parameter of the invention. However, the inventors have observed that, when the particle size increases, a longer period of time must elapse between the preparation of the composition and its use, as if it then required more time for a reaction to take place. occur, between phospholipids and the surface of the basic compound particles. The inventors tested various basic compounds, and found that the best results were obtained with compounds which are not completely soluble in the suspension of phospholipids in water, at least part of which therefore remains in suspension, or which form a heterogeneous mixture. with suspended phospholipids. Mention may thus be made, by way of example, of barium hydroxide, strontium hydroxide and tallow propylene diamine, in addition to calcium hydroxide and stearylamine cited in the examples. Other compounds will clearly appear to a person skilled in the art, on reading the present description.

Of course, the invention is not limited to the embodiments described, which have been chosen only by way of example.

Claims

1. Lubricating composition, characterized in that it consists of a suspension in water of a mixture of phospholipids and a basic mineral or organic compound.

2. Composition according to claim 1, characterized in that it is constituted, on the basis of the total weight of the composition, of:

- 5 to 40% by weight of phospholipids - 5 to 40% by weight of the basic compound

- 90 to 20% by weight of water.

3. Composition according to any one of claims 1 and 2, characterized in that the phospholipids are present in the form of lecithin.

4. Composition according to any one of claims 1 to 3, characterized in that the lecithin is soy lecithin.

5. Composition according to any one of claims 1 to 4, characterized in that the basic compound is at least partially in suspension.

6. Compo_.ition according to any one of claims 1 to 5, characterized in that the basic compound is an amine or an amine derivative.

7. Composition according to any one of claims 1 to 5, characterized in that the basic compound is a hydroxide of a metal from group lia of the periodic table of the elements.

8. Composition according to any one of the preceding claims, characterized in that it further comprises an acid, for neutralizing the alkalinity of the basic compound after its interaction with the phospholipids.