DE1288080B - Process for the manufacture of a clay product suitable as a thickening agent - Google Patents

Description

The invention relates to a method for producing a thickener for an organic Liquid, e.g. B. for a base lubricating oil in the production of lubricating grease, suitable clay product.

In some applications of clays as thickeners for organic liquids and in particular For lubricants it is necessary to use the clays to protect the actual clay surfaces to coat hydrophobic surfaces.

There are numerous water repellant agents for coating the clays with hydrophobic surfaces known. Examples of such agents are dodecylammonium chloride, octadecylammonium chloride, dicoconut acid dimethylammonium chloride and the corresponding bromides. Other examples of water repellants are hydrophobic surfactants Agents that are at least partially physically absorbed by the clay surfaces. This includes long chain fatty acid amines, e.g. B. Octadecylamine, and in particular aminoamides or imidazolines, which are formed from polyalkylene polyamines and saturated or unsaturated fatty acids. as Water repellants can also be polymeric materials, e.g. B. amino resins, phenolic resins and Polyepoxy resins, can be used to coat clay surfaces.

In the case of the above-mentioned water repellent agents, the effectiveness of the agents can be increased by treating a hydrosol of a base-exchanging clay with a strong mineral acid such as hydrochloric acid, sulfuric acid, nitric acid or phosphoric acid. Of these acids, phosphoric acid has proven to be the most suitable and is the most widely used in the manufacture of clays for the manufacture of grease. The acid treatment of the clay and the coating with water repellants is e.g. B. from British Patent 794,711 known.

It has now been found that boric acid is used to pretreat the clay before treating it can be used with a water repellent, although it is a weak acid. the Pretreatment with boric acid gives advantages that cannot be achieved by using strong mineral acids will. . ■ ..,., ..-

The invention thus relates to a method for producing a suitable thickener Clay product by treating a hydrosol of a base-exchanging clay with acid and coating the surface of the acidified clay with a water-repellent agent, which thereby is characterized in that boric acid is used as the acid.

The time required for sufficient acidification of the clay present as hydrosol can thereby be reduced Shorten that the hydrosol and boric acid together before treatment with the water repellent be heated. For this purpose, the hydrosol and boric acid can be used with advantage, for. B. on at least 66 ° C, preferably to at least 88 ° C and in particular to 93 to 100 ° C.

A clay product particularly well suited for the production of lubricating grease is obtained by the fact that the Water from the water-repellent (acidified and treated with the water-repellent) Sound is removed (partially or completely), e.g. B. by evaporation. One made this way Clay has the advantage that it can be used with a lubricating oil even after a long period of storage

■ can process grease.

A lubricating grease can also be produced from a clay product produced according to the invention by that the present in hydrosol form, acidified and made hydrophobic clay Lubricating oil clogs, forming lumps and a separate water phase. From the ones left behind The water is evaporated in lumps.

ίο Preferably used when acidifying the hydrosol the proportions of hydrosol and boric acid selected so that the added amount of boric acid corresponds at least to the base exchange capacity of the dry clay, i.e. the base exchange clay is preferably added at least the amount of boric acid that is sufficient to remove all basic metals mostly present as sodium, potassium, and calcium ions, replacing in the clay. This gives you an acidified clay whose adsorption properties

ao shafts are particularly favorable with regard to the hydrophobizing agents.

In the case of a hectorite, the hydrosol is preferably 5; up to 50 percent by weight and in particular no more than 35 weight percent based on the weight of the dry clay was added. It is particularly preferred to use 10 to 20 percent by weight boric acid, based on the Dry clay weight. When using at least 5, in particular at least 10 percent by weight Boric acid is the one that can be obtained by acidifying the clay with boric acid favorable effects particularly noticeable, while through the use of more than 20, in particular More than 50 percent by weight boric acid does not produce such an improvement in the product that it does would justify the additional costs. The boric acid is preferably in the form of an aqueous Solution used because the application in this form is particularly simple and expedient.

A clay suitable for the process according to the invention should have a high base exchange capacity, preferably 60 to 100 meq. Exchangeable base per 100 g of clay. Examples of such a clay are montmorillonites, especially sodium, ca ^ m, lithium and other bentonites, ζ. Β. Wyoming bentonite, magnesium bentonite (hectorite) and saponite. The clay is preferably treated to remove the gait normally associated with it. This can be done by dispersing the raw clay in water, the mixture settling in layers which can be separated from one another by virtue of their gravity or, preferably, by centrifugation at high speed. During dispersion, the clay forms a hydrosol with the water. The separated hydrosol preferably contains 1 to 5 weight percent clay so that it is relatively liquid and, e.g. B. by pumping, can be easily transported.
The water repellent such as any of the above can be added directly to the acidified hydrosol. If an organic polymer is used as the water-repellent agent, the monomeric reactants required for the preparation of the agent in question are preferably polymerized in the presence of the acidified hydrosol. This has the advantage that in this way the clay can be compared easily and quickly with the water-repellent

Agent serving organic polymer leaves over.

In the method according to the invention, a water-repellent agent is preferably used which consists of an amino amide or an imidazoline, which consists of a fatty acid and a polyethylene polyamine are formed. This measure is preferred because such water-repellent agents make hydrophobic, Clay products produced according to the invention are particularly good as thickeners for producing lubricating grease are suitable.

When the invention can be prepared according clay product is used as the thickener component of a grease, the lubricating oil with the clay to the grease preparation is preferably homogenized at 16 to 77 ⁰ C. If the grease is prepared directly from the clay product without prior separation and drying of the clay, the water-repellent agent can be added to the acidified clay or to the base lubricating oil, optionally with a volatile solvent, or together with a smaller amount of lubricating oil to the clay. In either case, the hydrosol is essentially dehydrated to remove excess acid.

The invention will now be illustrated by the following examples. To prove the good properties the clay products treated according to the invention are used to produce lubricating greases and examined.

example 1

Raw hectorite clay is dispersed in water and centrifuged to remove the gangue, leaving a Clay hydrosol is produced, which contains about 1.5 to 3.5 percent by weight of clay. Two separate portions of the clay hydrosol are based on 6 percent by weight aqueous boric acid and 8 percent by weight phosphoric acid acidified to the weight of the dry, de-gaited clay. To each of the acidified Clay hydrosols are added to the water repellent in an amount that is about 60 percent by weight of the dry clay. An amino amide is used as a water repellent, made by reacting long-chain fatty acids with a mixture of polyethylene polyamines has been. In addition, sodium nitrite becomes the acidic one as an anti-corrosion agent Clay hydrosol added. The clay mixtures are processed into "dry" powders by reducing their moisture content by spray drying in a dryer with a rotating cone to below 5 percent by weight is reduced.

The two resulting oleophilic clay powders have the following compositions:

The clay powders produced in this way are each separately mixed with a mineral lubricating oil which has a viscosity of 75 SUS (Saybolt Universal Seconds) at 98.9 ° C and to which a long-chain substituted imidazoline surfactant (made from tall oil fatty acids) has been added in an amount equal to 10 percent by weight of the dry clay. The mixtures of the oleophilic clay and the lubricating oil are then passed twice through a homogenizer at 353 kg / cm ² to produce the lubricating grease.

The properties of the resulting greases are given in the following table.

Properties of the greases

Acid treatment of clay.
Penetration, dmm

unprocessed

processed

processed 100,000 work

g ^än 8 ^e

100 ⁰ C heated rolling test

148.9 ⁰ C temperature resistance penetration, dmm

H ₃ BO ₃

281 280

279 36

130

H ₃ PO ₄

291 307

297 39 V.

110

The above results show that the boric acid treated clay both had better yields (Thickening capacity) as well as greater high temperature resistance.

Example 2

Composition of with acid treated Tones Hectorite clay, percent by weight. H ₃ BO ₃ , weight percent H ₃ PO ₄ , weight percent Water repellent, Weight percent NaNO ₂ , percent by weight Weight percent ash 52 54.5 8.5 - - 4.5 31 32.5 8.5 8.5 59 59.5

According to Example 1, two separate portions of a clay hydrosol made from hectorite freed from gangue, each of which contains 1.5 to 3.5 percent by weight of clay, with 9 percent by weight of boric acid and 8 percent by weight of phosphoric acid, based on the amount of clay, at 93 and 88, respectively ° C acidified. To each of these acid-treated hydrosols, the amino amide as a water-repellent agent and the mineral lubricating oil according to Example 1, which also contains a small additional amount of the water-repellent agent, are added. After these ingredients are mixed together, "pearls" are formed and a layer of water is separated from them. The remaining "pearls" are ^{heated to 127 to 143 °} C. for 15 to 20 minutes in order to remove the remaining water by evaporation, and a solution of sodium nitrite in water in a ratio of 40:60 is added to the mixture that is still hot . When the mixture is cooled to 121 ⁰ C, a small amount of phenyl-a-naphthylamine is added as an antioxidant. The mixture is then cooled and milled.

It turns out that the separation of the water from the "pearls" in the case of that treated with boric acid Tones runs much faster than with the clay treated with phosphoric acid.

The resulting greases have the following compositions and penetrations.

Composition and properties of lubricating greases

Acid treatment of clay ... H ₃ BO ₃ H ₃ PO ₄ Hectorite clay, percent by weight ... 5 5 Water repellent des Tones, weight percent 3 3 Water repellent in the oil, Weight percent 0.4 0.4 NaNO ₈ , weight percent 0.6 0.6 Penetration, dmm unprocessed 275 291 processed 288 302

10

The table shows that the boric acid treated clay gives an improved grease.

Claims (8)

Patent claims: 1. Process for the preparation of a thickener suitable clay product by treating a hydrosol of a base exchange Tones with acid and coating the surfaces of the acidified clay with an a water-repellent agent, characterized in that that boric acid is used as the acid. 2. The method according to claim 1, characterized in that the hydrosol and the boric acid are heated together before the treatment with the water-repellent agent, preferably to at least 88 ^° C., in particular to 93 to 100 ^° C. 3. The method according to claim 1 and 2, characterized in that the water from the water-repellent Sound is removed. 4. The method according to claim 1 to 3, characterized in that the added amount of boric acid corresponds to at least the base exchange capacity of the dry clay. 5. The method according to claim 4, characterized in that the hydrosol 5 to 50 percent by weight, preferably 10 to 20 weight percent boric acid based on the weight of the dry Tones, be admitted. 6. The method according to claim 1 to 5, characterized in that the boric acid in the form of a aqueous solution is used. 7. The method according to claim 1 to 6, characterized in that the water-repellent agent consists of an amino amide or an imidazoline, which consists of a fatty acid and a polyethylene are formed. 8. The method according to claim 1 to 6, characterized in that as a water-repellent agent an organic polymer is used, the necessary for the preparation of the agent in question polymerized monomeric reactants in the presence of the acidified hydrosol will.