DD298521A5 - LUBRICATION AND FUNCTIONAL FLUID FOR VERY LOW TEMPERATURES - Google Patents

Abstract

The invention relates to lubricating and functional fluids for very low temperatures, in particular for use in hydraulic systems at operating temperatures of 60C to 60C. The proposed fluids consist of a combination of a n-paraffin-hydrocarbon mixture with a polyalkylbenzene mixture, a polymethacrylate or polyisobutene viscosity index improver, a zinc dialkyldithiophosphate-based oxidation inhibitor, and a phosphate-based wear inhibitor. Hydraulic systems; hydrocarbons; Polyalkylbenzolgemisch; polymethacrylate; polyisobutene; zinc dialkyldithiophosphate; alkyl phenol; Phosphate-based wear inhibitor}

Description

Field of application of the invention

The invention relates to lubricating and functional fluids for very low temperatures, in particular for use in hydraulic systems at operating temperatures of -60 ° C to +60 ⁶ C.

Characteristic of the known technical solutions

Lubricating and functional fluids for very low temperatures should have a pour point of less than -60 ° C, with viscosity values of a maximum of 1250 to 3000 mmVs being required for the lower operating temperatures. At the same time, minimum viscosities are prescribed for the upper operating temperatures. The minimum viscosity at 50 ° C should be 4 to 10 mmVs or at 100 ⁰ C 3.5-5.5 mmVs.

This requires a very good viscosity-temperature behavior and for the maximum requirement Vl values of> 340.

Due to the requirement for the low viscosity of the refrigerant, a compromise must be made with regard to the flash point and the onset of boiling.

In product specifications, therefore, flash points of up to 92 ° C and a boiling point from 220 ° C are permitted in some cases (GOST 6794-83). Known brand name products based on phthalic mineral oils have the required low values.

Another important requirement is the compatibility with conventional sealing materials. This requirement severely restricts the choice of basic fluids and is only met by fluids based on mineral oils and synthetic hydrocarbons.

These complex and extreme requirements for a lubricating and functional fluid have so far only been partially met.

German Patent 2531207 describes propylene oligomers having a flash point above 100X and a favorable swelling behavior towards sealing materials. By admixing naphthenbasischer mineral oils sine partial improvement is possible. Likewise, in FRG patent 2531210, a paraffinic hydrocarbon oil based on mineral or polypropylene is used, and the admixing of hydrogenated cyclopentadiene improves the swelling properties with regard to sealing materials and the cold behavior. In both applications, the extreme requirements for the cold and viscosity-temperature behavior are not met.

US Pat. Nos. 4,537,696 and 4,519,932 disclose hydrogenated decene-1 oligomers as the base liquid alone or with mono or diester moieties and known polymethacrylate-based VI improvers. The products meet the flashpoint requirements of at least 100 ° C and the minimum viscosities at the upper service temperatures.

On the other hand, lower values must be accepted for cold and viscosity-temperature behavior.

Investigations of known low-temperature hydraulic fluids showed that the requirements for the cold and viscosity-temperature behavior are met, but the flash point of at least 100 ⁰ C is not achieved. Also in favor of the required cold behavior worse values are obtained in the Siedelage.

A major disadvantage of all known solutions is that the base oils used are the expensive α-olefin polymers or the sparingly available naphthenic mineral oils. In the case of naphthenic oils, there is a worldwide shortage and supply in the future is not secured (BRD patent 2531210, column 2).

Object of the invention

The aim of the invention is to produce a lubricating and functional fluid for very low temperatures, especially in the application range between + 60 ° C to -6O ⁰ C based on domestic raw materials cost, the special requirements in the cold and viscosity-temperature behavior, as in particular in low-temperature hydraulic systems are required suffice.

Object of the invention

The object of the invention is to develop lubricants and functional fluids based on hydrocarbons, which are superior in terms of the fluid properties of known functional fluids and thus suitable for improving the safety-related code of these fluids.

The liquids to be developed should be one; Pour point of less than -60 ⁰ C, a viscosity at 5O ⁰ C of at least 4 to 10mmVs, at -30 ° C from 60 to 310 mmVs, at -50 ⁰ C from 220 to 2 500mmVs, a closed-cup flash point of greater than 100 ⁰ C, have a boiling start greater than 235 ⁰ C and a viscosity index greater than 340.

According to the invention wild the task by a mixture of

44.0 to 91.8 parts by weight in% of a n-paraffin-low hydrocarbon mixture having a closed-cup flash point of at least 100 ⁰ C, a boiling point of at least 235 ⁰ C, a Stockpuiikt of at least -70 ⁰ C and a viscosity at 50 ⁰ C of at least -7O ⁰ C and a viscosity at 5O ⁰ C of at least 1,8mmVs comprises from 5.0 to 35.0 parts by mass in% of a polyalkylbenzene mixture having an average molecular weight of 280-380, a viscosity at 5O ⁰ C in a 30% lüss'gkeit of at least 12 MMCs and elrsam pour point of at least -42 ⁰ C, 6.0 to 30.0 Masseteilo to 70% Visko3itäts index improver based on polymethacrylates having a cold-resistant Trägerf or 3, 0 to 15.0 parts by mass in% of polyisobutenes, 0.2 to 3.0 parts by mass in% of a C. xydationsinhibitors based on Zn dialkyldithiophosphate and / or a hindered alkylphenol and

0 to 5.0 parts by mass in% of a phosphate-based wear inhibitor, wherein the sum of the parts by mass of the polyalkylbenzene mixture and the viscosity index improver is at most 48 parts by mass in%.

As n-paraffinarmes hydrocarbon mixture is advantageously used a flow oil obtained in the C ₁₀ -C _{2 2} -n-Paraffingewinnung from mineral oils by means of molecular sieves. For this purpose, from a Cio-C _2J -Mineralölfraktion with a boiling range of 190 to 33O ⁰ C, a flash point of 74 to 86 ⁰ C and a pour point of maximum -28 ⁰ C, the η-paraffins separated by molecular sieves of type 5A, then 15 Distilled to 60 parts by mass in% of the η paraffin-low fraction at a pressure of 15 to 150 Torr and the distillation residue with 2 to 5 parts by mass in% bleaching earth at 50 to 8O ⁰ C and a contact time of 15 to 60 minutes post-treated.

As the polyalkylbenzene mixture it is expedient to use a distillation residue which is obtained in the preparation of C 1 -C 3 -n-monoalkylbenzene from chloroparaffin and benzene according to Friedel-Crafts according to DE 160371.

As VI improvers, known, commercially available polymethacrylates and polyisobutenes can be used. At higher VI improver concentrations, it is necessary that the carrier liquid also has a low pour point.

It is favorable if the base liquid is used as the carrier medium.

As oxidation inhibitors are particularly good Zn dialkyldithiophosphates and sterically hindered phenols, such as. As di-tert-butylp-cresol (DBPC), suitable. For heavily loaded lubrication points is the use of a wear inhibitor based on aryl phosphate, such. B. tricresyl phosphate, appropriate.

To meet the viscosity requirements at -50 ⁰ C and + 5O ⁰ C a very good viscosity-temperature behavior is required. It is necessary that even the base fluids have a high viscosity index (Vl). Both inventively proposed ßrundöle of n-paraffin and alkylaromatic hydrocarbons have a low Vl. Surprisingly, it has been found that in the mixture of these two types of base oil, a synergistic effect occurs in terms of Vl.

The base oil Miechung possesses a much higher Vl.

Thus arise from the mixture of n-paraffin hydrocarbons, as obtained in the separation of the η-paraffins from paraffin-based mineral oil fractions using molecular sieves of type 5 A with polyalkylene an average molecular weight of 312, a viscosity at 5O ⁰ C of 16.2 mmVs and a pour point of -53 ⁰ C following characteristics:

characteristic value An H. Parts by weight in% polyalkylbenzene (in n-paraffin-lean mineral oil) 0 18 20 30 133 <-70 97 <-70 91 <-70 40 100 Visc. Index Stockpkt. ⁰ C -12 <-70 86 <-70 64 -53

A further advantage of the n-paraffin-hydrocarbon mixture is that it has a higher flash point and boiling point compared to naphthenic mineral oils of comparable viscosity and a long-term supply is ensured. Compared with the synthetic base oils based on olofine polymers, the production costs are low. The behavior towards sealing materials shows a slightly increased swelling tendency compared to naphthenic mineral oils. The mechanical properties are changed only insignificantly. Since a certain swelling air better sealing is desirable, there are no disadvantages for the P.axiseinsatz.

AusfOhrungsbelsplele

example 1

52.0 parts by mass in% of a n-paraffin hydrocarbon mixture, which was obtained by separation of the η-paraffins from a paraffin-based mineral oil fraction by means of molecular sieves type 5 A and a viscosity at 50 ° C of 2.13 mm ² / s, a plan imp closed crucible of 104 ⁰ C, a boiling point of 246 ⁰ C and a pour point of less than -70 ⁰ C, 16.0 parts by mass in% of a polyalkylbenzene having an average molecular weight of 288, a viscosity at 5O ⁰ C of 12.6 mm ² / s and a pour point of -58 ⁰ C, 30.0 parts by mass in% of a 55% polymethacrylate having a viscosity boi 5O ⁰ C of 368mm ² / s in a cold-resistant mineral oil fraction 1.8 parts by mass of a Zn dialkyldithiophosphate with a Acid number of 2.54mgKOH / g and a Zn content of 4.13 parts by mass in% and 0.2 parts by mass in% di-tert-butylparacresol were stirred at 50 to 60 ⁰ C for 30 minutes.

The resulting lubricating oil mixture met the requirements in the cold and viscosity-temperature behavior, the flash point and had a relatively high boiling point. The values are summarized in Table 1.

Example 2

86.0 parts by mass in% of an n-para-aromatic hydrocarbon mixture, as described in Example 1,

5.5 parts by mass in% of a polyalkylbenzene Gemischos having an average molecular weight of 358, a viscosity at 50 ° C of 21.2 mmVs and a pour point of -44 ⁰ C, 6.0 parts by mass in% of a 70% polymethacrylate in one cold-resistant mineral oil fraction 2.3 parts by weight in% of a Zn dialkyldithiophosphate having an acid number of 2.54 mg KOH / g and a Zn content of 4.13 parts by mass in% and 0.2 parts by mass in% di-tert-butyl-p Cresol were stirred at 50 to + 6O ⁰ C for 30 minutes.

The resulting mixture met the extreme demands of a cryogenic hydraulic fluid. The values are included in Table 1.

Example 3

50.9 parts by mass in% of a n-paraffin-lean hydrocarbon mixture, as used in Example 1 34.6 parts by mass in% of a polyalkylbenzene mixture, as described in Example 1 10.5 parts by mass in% of a 40% polymethacrylate in a mineral oil fraction 0.5 Parts by weight of% di-tert-butyl-p-cresol and 3.5 parts by weight in% tricresyl phosphate were stirred at 50 to + 6O ⁰ C for 30 minutes. The values can be taken from the tabs 1.

Example 4

46.8 parts by weight in% of a n-paraffin-low hydrocarbon mixture, as described in Example 1 28.0 parts by mass of a polyalkylbenzene mixture having an average molecular weight of 312, a viscosity at 5O ⁰ C of 16.2 mnr / s and a pour point before, -53 ° C, 20.0 parts by mass in% of a 33% polymethacrylate in a mineral oil fraction 0.2 parts by mass in% di-tert-butyl-p-cresol and 5.0 parts by mass in% tricresyl phosphate were at 50 to + 6O ⁰ C stirred for 30 minutes. The values can be found in Table 1.

Example 5

91.5 parts by mass in% of a n-paraffin-lean hydrocarbon mixture, as described in Example 1, 5.0 parts by mass in% of a polyalkylbenzene mixture, as described in Example 4 3.0 parts by mass in% of a commercially available polyisobutenes and 0.5 parts by mass in% di-tert-butyl-p-cresol was stirred at -50 to + 6O ⁰ C for 30 minutes. The values can be found in Table 1.

Table 1

product Visk.b.50 ° C Visk.b.-30 ° C Visk. Index Stockpkt. Flammpkt. Siedebeg. mm ² / s   NMVs - ⁰ C ⁰ C ⁰ C example 1 12.42 168 426 -64 107 248 Example 2 4.85 46 408 -62 103 245 Example 3 10.48 218 342 <-70 106 247 Example 4 16.40 287 406 -60 100 250 Example 5 6.20 68.7 398 <-70 102 244 Brand oil 1 4.19 62.5 397 <-70 86 226 Markenöl2 10.46 199.1 348 <-70 88 228 Brand oil 3 10.96 222.0 376 <-70 81 234

Prior art brand oils 1-3 contain naphthenic mineral oils as base oils and are the most representative low temperature hydraulic fluids of the world market. They have very good cold properties, but the flash point in the closed crucible and the volatility or the onset of boiling do not meet the safety requirements.

Compatibility with a conventional standard sealing material for hydraulic systems has been studied compared to branded oils at 70 ° C and 168 hours test time. It was found that the n-paraffine

Hydrocarbon mixture increased swelling, the polyalkylbenzene have a very low swelling. The mixture of both base oils gives an average swelling, as it is desirable for a good seal.

This effect was not to be expected since, as a rule, in the case of mixtures the swelling approaches the values of the base oil with the highest swelling.

The values are summarized in Table 2 below.

Table 2

product By volume swelling Ground-swell Markenöl2 +0.52 -0.92 Markenöl3 +4.51 +2.00 polyalkyl -0.47 -1.21 n-paraffin poor Hydrocarbon +9.16 +4.66 example 1 +6.36 +3.05

Claims (4)

1. Lubricating and functional fluid for very low temperatures based on hydrocarbons, characterized in that it consists of 44.0 to 91.8 parts by mass in% of a n-paraffinic hydrocarbon mixture having a closed-cup flash point of at least 100 ⁰ C, a Siedebeginn of at least 235 ° C, a pour point of at least -70 ^c C and a viscosity at 50 ⁰ C of at least 1.80mm ² / s, 5.0 to 35.0 parts by mass of a Polyalkylbenzolgemisches having an average molecular weight of 280-380, has a viscosity at 50 ⁰ C of at least 12.0mm ² / s and pin-pour point of at least -42 ⁰ C; 8.0 to 30.0 parts by mass in% of a 30 to 70% viscosity index improver based on a polymethacrylate and a cold-resistant carrier liquid or 3.0 to 15.0 mass parts in% of a polyisobutene, 0.2 to 3.0 parts by weight in% of an oxidation inhibitor based on Zn dialkyldithiophosphate and / or a hindered alkylphenol and 0 to 5.0 parts by mass in% of a phosphate-based wear inhibitor. 2. lubricating and functional fluid according to claim ¹ , characterized in that the sum of the mass fractions of the Polyalkylbeüzolkomponente and the viscosity index improver is a maximum of 48 parts by mass in%. 3. lubricating and functional fluid according to claim 1 and 2, characterized in that as n-paraffinic hydrocarbon mixture in the C ₁₀ -C ₂ 2-n-Paraffingewinnung from mineral oils obtained by means of molecular sieves of the type 5 A flow oil used. 4. lubricating and functional fluid according to claim 1 and 2, characterized in that a distillation residue is used as Polyalkylbenzolkomponente obtained in the preparation of Ciö-Cia-n-Monoalkylnenzol from chlorinated paraffins and benzene according to Friedel-Crafts and refined by known methods ,