RU2586686C2 - Grease lubricant with improved anti-wear and extreme pressure properties and preparation method thereof - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: present invention relates to grease which contains mineral or synthetic oil, thickener - polyurea and antiwear filler - wastes from production of mineral fertiliser - dehydrated phosphogypsum with following ratio of components, wt%: polyurea 1-15, dehydrated phosphogypsum - 2-70 and mineral or synthetic oil - balance. Present invention relates to a method of producing grease

EFFECT: technical result of present invention is improved antiwear and antiscoring properties of disclosed lubricant when making lubricant using a simple method and recycling large-tonnage wastes-phosphogypsum.

2 cl, 11 ex, 3 tbl

Description

The invention relates to the field of oil refining and petrochemicals, in particular to the so-called “white” lubricants (pastes) intended for use in friction units of various machines and mechanisms, including rolling bearings.

“White” greases-pastes include greases filled with chemically active powders - sulfides, sulfates, borates, fluorides, etc. Such pastes with a filler content of up to 10% are called greases, and with their content of more than 10% they are called pastes and are used in friction units of various machines and mechanisms, they are especially effective under conditions of vibration loading (vibration), and unlike traditional lubricants, filled with graphite and molybdenum disulfide, workable in rolling bearings. In the literature, such lubricants (pastes) are called “white” pastes.

The most effective lubricant compositions that use a double filler: a carrier (which are oxides, hydroxides, carbonates, acetates) and the chemically active powder itself (Reference. T. Mang, W. Dresel. Lubricants. - St. Petersburg; 2012 g., p. 783).

Well-known development of the American company AMOCO Corporation, which claimed a series of patents for plastic filled greases with polyurea thickener.

Thus, the lubricant composition is known, which is described in US Pat. No. 4,902,435 A, in which tricalcium phosphate and calcium carbonate are used as a filler, and in addition, a complex calcium soap is used as a thickener.

In the lubricant of US Pat. No. 4,830,768 A, tricalcium phosphate and calcium carbonate are used as filler.

The grease of CA 2010924 A1 of the same company describes a grease composition containing tricalcium phosphate, calcium carbonate and a water-resistant polymer as a filler.

Closest to the claimed is a grease according to US 5223161 A, which contains,% wt .:

base oil (mineral or synthetic) - 45-85 polyurea thickener - 1-15 antiwear filler, containing calcium sulfate and calcium acetate - 0.2-40

To obtain this lubricant, anhydrous calcium sulfate is mixed with a base oil, polyurea, previously also mixed with a base oil, and a composition obtained by mixing polyurea in a base oil at 170 ° F, adding another base oil, re-mixing, introducing calcium hydroxide, mixing also with 170 ° F until a homogeneous structure is formed, glacial acetic acid is added, stirred at 180 ° F for 30 minutes, the mixed composition is heated to 300 ° F, and the reaction vessel is evacuated for 10 mi Cooling the composition after removal of the vacuum to 170 ° F and homogenization by grinding.

The resulting grease has the following properties: dropping point of about 500 ° F (260 ° C), penetration from 284 to 319 units, oil separation in 24 hours at 212 ° F (100 ° C) from 1.3% to 2.6%, however, despite good tribological characteristics (critical load - Pk, welding load - Pbc and wear spot diameter - Dp), they are all inferior to traditional lubricants (pastes) based on molybdenum disulphide in these indicators. In addition, the method for producing lubricant is complex, multi-stage.

Lubricants according to other analogues mentioned above have approximately the same properties.

The objective of the invention is to develop a grease composition with improved tribological characteristics and to increase its anti-wear and extreme pressure properties to the level of traditional lubricants with molybdenum disulfide, to replace which it could be used, as well as to develop a simple method for producing a lubricant with such properties.

This object is achieved by the fact that the proposed grease based on mineral or synthetic oil, a polyurea thickener and antiwear filler containing anhydrous calcium sulfate, which as the specified filler contains waste production of mineral fertilizers - dehydrated phosphogypsum in the following ratio, wt.%:

polyurea 1-15

dehydrated phosphogypsum 2-70

mineral or synthetic oil - the rest.

The lubricant production method involves the complete dehydration of phosphogypsum by roasting it at a temperature of 450-700 ° C, adding dehydrated phosphogypsum to a composition including mineral or synthetic oil and polyurea, and mixing.

Phosphogypsum is a waste product of the production of mineral fertilizers, which is mainly based on calcium sulfate in the form of gypsum and tricalcium phosphate mixed with aluminum, sodium, potassium oxides, as well as a small amount of silicates and fluorides.

This waste is generated during the production of phosphate fertilizers from natural raw materials - apatite or phosphorite, the basis of which is water-insoluble tricalcium phosphate. The scheme for the conversion of water-insoluble tricalcium phosphate into soluble secondary phosphate (precipitate) is given below (see Glinka NL General Chemistry. 1971, p. 411):

$${\text{Ca}}_{\text{3}}{\text{(PO4)}}_{\text{2}}+{\text{3 H}}_{\text{2}}{\text{SO}}_{\text{four}}={\text{3 CaSO}}_{\text{four}}\downarrow +{\text{2H}}_{\text{3}}{\text{PO}}_{\text{four}}\text{(one)}$$

. $${\text{H}}_{\text{3}}{\text{PO}}_{\text{four}}+{\text{Ca (OH)}}_{\text{2}}={\text{CaHPO}}_{\text{four}}\ast {\text{H}}_{\text{2}}\text{O}+{\text{H}}_{\text{2}}\text{O}\text{(2)}$$

.

The mixture of an insoluble precipitate of calcium sulfate with other insoluble compounds formed by this scheme forms the basis of phosphogypsum - a waste of this production of phosphate fertilizers.

Table 1 shows the composition of phosphogypsum - waste production of mineral fertilizers. Given the complex mixture of waste generated, a chemical analysis of them is presented included in them in the form of oxides of elements.

Table 1 Qualitative composition of phosphogypsum H ₂ O General In terms of dry matter,% wt. P ₂ O ₅ Common P ₂ O ₅ F total F Water. Na ₂ O K ₂ O SiO ₂ Al ₂ O ₃ Fe ₂ O ₃ Cao SO ₃ Sro REE 25-32 1.0-1.5 0.6-0.8 0.4-0.6 0.2-0.3 0.1-0.3 0.06-0.1 0.4-0.7 0.15-0.27 0.1-0.3 38-40 53-56 1.9-1.25 0.8-0.9

For use as an antiwear and extreme pressure filler, only specially prepared phosphogypsum can be used, as the crystallization water included in the waste contributes to corrosion and must be disposed of. It is known that complete dehydration of calcium sulfate (gypsum) occurs at 450-700 ° C. This temperature is also used for dehydration of waste (phosphogypsum). Fully dehydrated phosphogypsum is mainly calcium sulfate and tricalcium phosphate mixed with small amounts of fluorides, silicates and oxides of rare-earth elements (REE) (see table No. 1 without crystallization water).

Examples 1-7

Polyurea test lubricants are prepared by adding amines and isocyanates to the mineral oil (I-50 industrial oil) in quantities required for the formation of polyurea at a temperature of 80 ° C for 0.5 hour, then the temperature is raised to 150 ° C until complete polyurea formation reactions. Then, to a composition comprising mineral oil and polyurea, at a temperature of 60-80 ° C and stirring, filler is added in an amount of 2, 5, 10, 20, 30, 50, or 70 wt.%, The lubricant is mixed and homogenized (Considering the filler changes the penetration of the lubricant, the amount of thickener - polyurea changed so that the penetration remains at the level of 284-319 units, as in the analogue lubricant according to US 5223161 A).

On a four-ball friction machine according to GOST 9490, tribological characteristics of the lubricant are determined at different filler contents. The extreme pressure properties of lubricants are evaluated by the coefficients Pk — the critical load and Pcv — the welding load, so that the higher they are, the better the specified lubricant properties. Anti-wear properties are evaluated by the wear spot - D and - the smaller it is, the higher the anti-wear properties of lubricants. The test results on a four-ball lubrication friction machine at various filler contents are presented in table 2.

table 2 The effect of filler content on the tribological characteristics of the inventive lubricant No. of examples The composition of the lubricant,% wt. Tribological characteristics Filler - dehydrated phosphogypsum Mineral oil Polyurea Pkr., Kgf Rsv., Kgf D and mm one 2 86 12 84 200 0.72 2 5 83 12 126 315 0.68 3 10 78 12 160 630 0.58 four twenty 68 12 178 708 0.56 5 thirty 58 12 200 750 0.55 6 fifty 38 12 250 more than 800 0.53 7 70 eighteen 12 no data * no data * 0.52 * the value of these indicators exceeds the measuring capabilities of the four-ball friction machine

Examples 8-11 (comparative)

Comparison of the properties of the lubricant according to example 3, containing 10% wt. dehydrated phosphogypsum, with the properties of analog lubricants. For comparison, use the lubricants according to the patent US 4830767 A (lubricant No. 1, filler tricalcium phosphate and calcium carbonate) and according to the patent US 5223161 A (lubricant No. 2, filler calcium sulphate and calcium acetate), as well as polyurea lubricant with a traditional filler - molybdenum disulfide and lubricant without filler. For all lubricants, in addition to testing the tribological properties on a four-ball friction machine according to GOST 9490, also check: dropping point according to GOST 6793, penetration according to GOST 5346 and colloidal stability (KSA) according to GOST 7142 at 100 ° C for 24 hours.

Table 3 shows the performance of the claimed grease with phosphogypsum in comparison with the above greases.

Table 3 Physico-chemical properties of filled polyurea greases No. of examples Lubricant name physical and chemical indicators Drop temperature ° C Penetration, units KSA Tribological characteristics Pkr., Kgf Rsv., Kgf D and mm 3 Phosphogypsum grease * More than 260 285 4.0 160 630 0.58 8 Grease No. 1 * 255 290 2.6 126 422 0.62 9 Grease No. 2 * 260 304 4.4 126 473 0.64 10 Molybdenum disulfide grease * More than 260 290 3.8 141 500 0.72 eleven No lubricant ** 251 310 4.8 63 178 0.78 * composition,% wt .: industrial oil I-50 - 78, polyurea - 12, filler - 10 * composition,% wt: industrial oil I-50 - 88, polyurea - 12

For greases with dehydrated phosphogypsum prepared in synthetic oil - dioctylsebacinate (DOS), these figures are approximately 20% better.

A balanced mixture of compounds included in phosphogypsum, introduced into the inventive lubricants, as can be seen from Table 3, causes a synergistic effect when it is used and exceeds the tribological properties of polyurea lubricants declared by AMOCO with chemically active fillers in the form of calcium sulfate and calcium phosphate, and when This is not inferior to traditional molybdenum disulfide lubricants.

The declared lubricant is obtained in a simple way, and the use of waste - phosphogypsum improves the environmental situation in the regions where such waste exists.

Thus, the proposed composition of the grease with a concentration of phosphogypsum from 2% to 70% by weight, which is a waste product of mineral fertilizers, is close in terms of tribological characteristics to lubricants (pastes) filled with molybdenum disulfide. For example, for VNIINP-232 paste containing up to 70% MoS ₂ , data on Pcr. and Rsv. absent, i.e. the capabilities of the four-ball machine are completely exhausted and further filling does not make sense, because reached a maximum of Pcr. and Rsv., and the diameter of the wear spot no longer decreases with a further increase in the amount of filler (see Sinitsyn V.V. Grease in the USSR. M., Chemistry, 1979, p.241). The performance of the claimed lubricant, as can be seen from table 2, example 7, can also exceed the capabilities of the four-ball friction machine.

Claims (2)

1. Grease based on mineral or synthetic oil, a thickener - polyurea and antiwear filler containing anhydrous calcium sulfate, characterized in that as the specified filler it contains a waste product of the production of mineral fertilizers - dehydrated phosphogypsum in the following ratio, wt.%:
polyurea 1-15 dehydrated phosphogypsum 2-70 mineral or synthetic oil rest 2. The method of obtaining the lubricant according to claim 1, characterized in that it includes complete dehydration of phosphogypsum by roasting it at a temperature of 450-700 ° C, adding dehydrated phosphogypsum to a composition comprising mineral or synthetic oil and polyurea, mixing and homogenization.