LUBRICANT ADDITIVES FOR METAL WORKING

Abstract

Method for increasing lubrication in metal working processes by the use of phosphate esters of propoxylated and ethoxylated alcohols.

Claims

1) method for increasing lubrication in metal working processes comprising the step of adding to metal working fluids phosphate esters of formula I: ##STR00005## wherein R is the residue of one or more linear or branched C.sub.12-C.sub.18 aliphatic alcohols and at least 70% by weight of said aliphatic alcohols is made up of one or more linear or branched C.sub.14-C.sub.16 aliphatic alcohols; x is the average number of propoxy groups and ranges from 3 to 6.5; y is the average number of ethoxy groups and ranges from 3 to 8; R.sub.1 is hydrogen, an alkali metal, the ammonium ion, a protonated amine, a quaternary organic ammonium or an alkaline earth metal; R.sub.2 is like R.sub.1 or is a radical of formula: ##STR00006## wnerein R, x ana y nave tne same meaning as reported above.

2) The method of claim 1), wherein R is the residue of one or more linear or branched C.sub.12-C.sub.18 aliphatic alcohols and at least 80% by weight of said aliphatic alcohols is made up of one or more linear or branched C.sub.14-C.sub.16 aliphatic alcohols.

3) The method of claim 2), wherein R is the residue of one or more linear or branched C.sub.14-C.sub.16 aliphatic alcohols.

4) The method of claim 1), wherein x is a number from 3.5 to 5.5.

5) The method of claim 1), wherein y is a number from 4 to 6.5.

6) The method of claim 1), wherein x is a number from 3.5 to 4.5 and y is a number from 4.5 to 5.5.

7) The method of claim 1), wherein R.sub.1 is hydrogen, an alkali metal or a protonated amine.

8) A metal working fluid comprising from of 0.01 to 10 wt % of phosphate esters of formula I described in claim 1) and from 50 to 80 wt % of a lubricating oil.

9) A metal working fluid comprising from of 0.01 to 10 wt % of a phosphate esters of formula I described in claim 1) and from 50 to 80 wt % of water.

10) Use of the phosphate esters of formula I described in claim 1) as lubricating additive for metal working fluids.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0038] Preferably, in formula I R is the residue of one or more linear or branched C.sub.12-C.sub.18 aliphatic alcohol and at least 80% by weight, more preferably at least 90% by weight, most preferably at least 95% by weight, of said aliphatic alcohols is made up of one or more linear or branched C.sub.14-C.sub.16 aliphatic alcohols.

[0039] In a preferred embodiment, R is the residue of one or more linear or branched C.sub.14-C.sub.16 aliphatic alcohols.

[0040] In a more preferred embodiment, R is the residue of a mixture of linear and branched C.sub.14-C.sub.16 aliphatic alcohols.

[0041] In the most preferred embodiment, R is the residue of a mixture of C.sub.14-C.sub.15 linear and branched aliphatic alcohols.

[0042] Preferably, x is a number from 3.5 to 5.5, more preferably from 3.5 to 4.5.

[0043] Preferably, y is a number from 4 to 6.5, more preferably from 4.5 to 5.5. More preferably, x is a number from 3.5 to 5.5 and y is a number from 4 to 6.5.

[0044] Most preferably, x is a number from 3.5 to 4.5 and y is a number from 4.5 to 5.5.

[0045] Preferably, R.sub.1 is hydrogen, an alkali metal, the ammonium ion, a protonated amine or a quaternary organic ammonium. More preferably, R.sub.1 is hydrogen, an alkali metal, such as sodium or potassium, or a protonated amine. Protonated amines are particularly preferred. Examples of suitable amines are alkyl amines and alkanol amines, with ethanolamine, propanol amine and ethyl amine being the most preferred.

[0046] Examples of suitable esters of formula I include mixtures of phosphoric acid monoesters (degree of esterification=1) or mixtures of phosphoric acid diesters (degree of esterification=2) or mixtures of phosphoric acid monoesters and diesters.

[0047] Mixtures of monoesters and diesters having an average degree of esterification ranging from 0.9 to 1.8, preferably from 1.1 to 1.6, are preferred.

[0048] The esters of formula I may be produced by conventional methods.

[0049] For example, they may be prepared by esterifying the adduct resulting from the propoxylation and subsequent ethoxylation (with x moles propylene oxide and y moles ethylene oxide, respectively) of one or more linear or branched C.sub.12-C.sub.18 aliphatic alcohols, wherein at least 70% by weight of said alcohols is made up of one or more linear or branched C.sub.14-C.sub.16 aliphatic alcohols, with a phosphating agent, e.g. P.sub.2O.sub.5or phosphoric acid or a derivative thereof, for example a polyphosphoric acid, such as tetraphosphoric acid. The esterification into phosphoric esters is advantageously carried out at a temperature from 35 to 110° C. The alkoxylation steps are preferably carried out in the presence of a conventional catalyst, for example an alkali metal hydroxide.

[0050] According to the method of the present invention, the esters of formula I can be can be added to both oil-based metal working fluids and water-based metal working fluids. The latter being preferred for their higher environmental compatibility.

[0051] Metal working fluids comprising esters such as those disclosed herein can be finished fluids, concentrates or packages.

[0052] The oil-based metalworking fluid can comprise from of 0.01 to 10 wt % of said phosphate esters of formula I and from 50 to 80 wt % of at least one lubricating oil.

[0053] The at least one lubricating oil includes natural or synthetic lubricating oils.

[0054] Natural lubricating oils include animal oils, vegetable oils, mineral oils and mixtures thereof.

[0055] Synthetic lubricating oils include hydrocarbon oils, oils derived from hydrocracking, halo-substituted hydrocarbon oils, silicon-based oils, polyalphaolefins, such as those prepared from dodecene and decene, and esters such as an adipate. The synthetic oil can be at least in-part a polymer chosen, for example, among hydrogenated copolymers of styrene-butadiene, ethylene-propylene polymers, polyisobutenes, hydrogenated styrene-isoprene polymers, hydrogenated isoprene polymers, polyalkyl styrenes, etc.

[0056] Due to their compatibility with water and other desirable characteristics, the esters of formula I of this invention are particularly suitable as additives for water-based metal working fluids useful where, in addition to lubrication, a high degree of cooling is desired.

[0057] Usually, the water-based metal working fluid comprises from of 0.01 to 10 wt % of said phosphate esters of formula I and from 50 to 80 wt % of water. Typically, water-based lubricant systems of this type include dispersions and emulsions. The water-based metalworking fluids of the invention are obtained by mixing water and a lubricating oil and adding the esters of the invention and a suitable emulsifying or dispersing agent.

[0058] The lubricating oil can be chosen among natural or synthetic oils, such as those described above.

[0059] The emulsifying/dispersing agents can be selected from a wide variety of known compounds such as anionic, non-ionic, cationic and amphoteric surfactants and mixture thereof.

[0060] The water-based metalworking lubricant fluids can contain other additives including, for example, biocides, oxidation inhibitors, corrosion inhibitors, metal deactivators, anti-wear agents, extreme pressure additives, hydrodynamic additives, flow additives, defoamers, colorants, etc., and combinations thereof.

[0061] The esters of formula I are preferably used in an amount of 0.1 to 5 wt % on the basis of the total amount of the metal working fluid.

[0062] The esters of formula I are excellent lubricants for both ferrous and non-ferrous metals and the metal working fluids containing them can be used for a wide variety of applications.

[0063] Examples of these applications include metal cutting processes such as cutting, drilling, grinding, turning, milling, tapping and broaching, or metal forming processes, including rolling, forging, molding, stamping, casting, drawing and extruding.

EXAMPLES

[0064] The alkoxylated alcohols of Table 1 were reacted with phosphoric anhydride in a molar ratio of 3:1 for about 4 hours at 45-50° C. Mixtures of acidic fosforic esters with an esterification degree of about 1.5 were obtained.

[0065] Table 1 reports the chemical identity of the phosphate esters with the average number of propoxy groups (PO) and ethoxy groups (EO) and also their pour point (° C.), determined according to ASTM D97-17b.

TABLE-US-00001 TABLE 1 Identity Pour Point Reference* Lubhrophos LB 400 15 Example 1* Part. Branched C.sub.14-15 12 Alcohols 1.5 PO 4.5 EO Phosphate Example 2* Part. Branched C.sub.14-15  5 Alcohols 2.5 PO 4.5 EO Phosphate Example 3 Part. Branched C.sub.14-15 −3 Alcohols 4 PO 5 EO Phosphate Example 4* 2-Heptyl 1 Undecanol 3.5 EO Phosphate 20 Example 5* Part. Branched C.sub.14-15 <−15  Alcohols 7.5 PO 5 EO Phosphate Example 6* Branched C.sub.13 Alcohol 4 PO 5 EO Phosphate <−15  Example 7* Linear C.sub.12 Alcohol 7.5 PO 5 EO Phosphate <−15  Example 8* Linear C.sub.12 Alcohol 4 PO 5 EO Phosphate <−15  *Comparative

[0066] Lubrication Tests

[0067] 2 wt % aqueous solutions of the esters of the Example 1-9, all neutralized with monopropanol amine, were used as test fluids.

[0068] The reference fluid was a 2.0 wt % aqueous solution of Lubhrophos LB400 (phosphate ester of ethoxylated cetyl/oleyl alcohols), a well-known and excellent lubricant.

[0069] Lubricating performances were evaluated with a Microtap II thread tapping machine (manufactured by Microtap USA, Inc.), which cuts threads in pre-drilled holes.

[0070] Tests were performed on 1018 cold rolled steel bars with 6.0 mm diameter holes.

[0071] Holes were isolated by mean of adhesive tape covering top and bottom of the bar.

[0072] Tapping was performed using uncoated high-speed steel (HSS) taps (for 1018 steel) and the amount of torque recorded. The tests were ran at the following RPM's: [0073] 500 RPM simulating a light-duty machining operation (Table 2); [0074] 650 RPM simulating a heavy-duty machining operation (Table 3); [0075] 750 RPM simulating a very heavy-duty machining operation (Table 4).

[0076] Test results are reported in Tables 2-4 as % efficiency. The % efficiency is the ratio of the torque value of the fluid containing the additive according to the invention (Example 3) to the torque value of fluid containing the comparative additives.

[0077] The fluid of Example 3 has been assigned an efficiency of 100%.

[0078] The test results demonstrate that the phosphate ester according to the invention shows a low pour point and largely outperforms at any operating speed the comparative phosphate esters and also the commercial product Lubrhophos LB-400.

[0079] The results obtained in the simulation of a very heavy-duty machining operation are particularly remarkable.

TABLE-US-00002 TABLE 2 % Efficiency Reference* 88.7 Example 1* 88.3 Example 2* 87.0 Example 3 100.0 Example 4* 85.0 Example 5* 86.3 Example 6* 90.7 Example 7* 89.9 Example 8* 92.2 *Comparative

TABLE-US-00003 TABLE 3 % Efficiency** Reference* 89.6 Example 1* 83.7 Example 2* 84.8 Example 3 100.0 Example 4* 84.8 Example 5* NA *Comparative **NA = Not Applicable, out of range of the instrument (>600 Ncm)

TABLE-US-00004 TABLE 4 % Efficiency ** Reference* NA Example 1* NA Example 2* 77.2 Example 3 100.0 Example 4* NA Example 5* NA *Comparative **NA = Not Applicable, out of range of the instrument (>600 Ncm)