WO2017036578A1 - Composition for minimum quantity lubrication, and use of same - Google Patents

Abstract

The invention relates to a lubricant composition and to the use of same for minimum quantity lubrication in the field of metalworking. The composition comprises 0.05 to 5 wt.% of emulsifier in relation to the total weight of the composition, and an amount of an aliphatic C_16-24 alcohol that makes the composition up to 100%. The emulsifier is selected from fatty alcohol polyalkylene glycol ethers or glycolic acid alkoxylate alkyl ethers or mixtures thereof.

Description

 COMPOSITION FOR MINIMUM-MEAT LUBRICATION AND THEIR

 USES This invention relates to a lubricant composition for minimal quantity lubrication in metal working and the use of the lubricant composition therefor.

In metal-working processes, a distinction is made between conventional wet machining, in which the cutting tool is flooded with a cooling lubricant, and dry machining without lubrication, in which the heat generated in the cutting process is mainly dissipated to the chip, tool and workpiece. While dry machining dispenses with lubricant, the heat flowing into the workpiece can adversely affect component accuracy, and the tool may wear earlier due to increased thermal stress. The cooling lubricants used in wet processing primarily provide cooling, lubrication and chip evacuation, but at the same time have an influence on non-productive times in the production process by collecting, processing or disposing of the cooling lubricants, and thus also for the costs of their purchasing, processing and disposal , Furthermore, environmental and health protection must be taken into account. The minimum quantity lubrication (MQL) or minimal quantity cooling lubrication (MMKS) forms a middle ground between wet machining and dry machining. Exact definitions for the "minimum amounts" do not exist, depending on the source up to 20 ml / h, 50 ml / h, 150 ml / h, or sometimes up to 500 ml / h referred to as MMS - but in all cases a clear difference to the usual amounts in the wet processing of 30,000 to 60,000 ml / h or significantly more before.

The minimum quantity lubrication offers a significant reduction in the supply and disposal technology for the cooling lubricant compared to wet processing, which enables longer service life and reduced process time. Furthermore, follow-up processes for cleaning the workpieces and also the tool can be reduced. Since minimum quantity lubrication means loss lubrication, only new, ie non-recycled or recycled lubricant is used so that biocides, fungicides and other additives can be dispensed with. However, there are increased demands on the lubricant, which must be matched to the workpiece material, machine parameters and tool material in order to achieve optimum results.

In general, for MMS, either synthetic ester oils or fatty alcohols are used, which are composed for the desired processing range in terms of evaporation and flash point. Synthetic esters are preferred for machining processes where effective lubrication is the most significant. When using fatty alcohols is less the lubrication than the cooling in the foreground. A composition based on a fatty alcohol for machining aluminum with minimum quantity lubrication is disclosed in EP 2 397 535 A1. The alcohol compound has 1 to 8 hydroxyl groups and 2 to 27 carbon atoms and is contained in the composition in an amount of 16 to 100% by weight. The remainder may be a mineral oil or synthetic oil, also ester oil. To improve the lubricating power of this composition, various additives are listed, which can be added to the composition.

It has been shown that even with minimum quantity lubrication, small amounts of the cooling lubricant remain on the workpiece around the cutting point and on the tool. On the one hand, the residues of lubricant on the workpiece can, on the one hand, help to avoid corrosion at the processing point, but on the other hand can also have a negative effect on subsequent production processes such as welding, gluing, painting, etc., and may therefore necessitate a cleaning step.

Water-miscible metalworking fluids that can be cleaned with water are considered unsuitable for minimum quantity lubrication because they do not have the required lubrication or flash point.

For cleaning a lubricant based on a saturated aliphatic mono-hydric C14 -18 alcohol adapted for cold working aluminum as a film on the surface of the workpiece, WO 91/06619 describes heating the workpiece so that the lubricant evaporates. Starting from this prior art, it is an object of the present invention to provide a minimum quantity lubricant which can be heated without heating and not only from the workpiece, but also from the tool and the machine tool can be cleaned easily.

This object is achieved by a lubricant composition having the features of claim 1. Further developments of the lubricant composition are set forth in the subclaims.

The simple cleaning using the lubricant composition is disclosed with the features of independent claim 8.

A lubricant composition according to the invention for minimal quantity lubrication in metalworking is composed to a major proportion of an aliphatic Cie-24 alcohol to which a small proportion of emulsifier is added, so that the

Lubricant is emulsifiable with water. In this way not only the workpiece, but also the tool and the processing space (eg machine interior) can be easily removed from the residues of the lubricant composition according to the invention by emulsification with water. However, care must be taken that the lubricant composition can not come into contact with water during storage and supply to the tool.

A preferred emulsifier may be a fatty alcohol polyalkylene glycol ether contained in the composition at 0.05 to 5% by weight, based on the total weight of the composition. Alternatively, the emulsifier may be a glycolic acid alkoxylate alkyl ether, the proportion of which in the composition ranges from 0.05 to 5% by weight, based on the total weight of the composition. However, it is also conceivable that mixtures of fatty alcohol-polyalkylene glycol ethers and glycolic acid alkethoxylate alkyl ethers are used as emulsifier with a weight fraction of 0.05 to 5 wt .-%, based on the total weight of the composition. The aliphatic Cie-24 alcohol is then in each case in a 100% of the composition complementary proportion.

The fatty alcohol polyalkylene glycol ether has the formula (I)

R * - [(CH ₂ CH ₂ O) x- (CH ₂ CH (CH 3) O) y] -R ¹ (I)

oder Ci6 mit n=5 zum Beispiel. Abweichungen bezüglich Basisalkohol, Art und Anzahl der Alkoxy-Einheiten sind ohne weiteres denkbar. wherein R ^{1 is} an aliphatic, branched or linear Cie- alkyl or alkenyl radical. R * may be a hydroxyl group. The variables x and y can be 0 to 10, provided that the sum x + y is from 1 to 10. The fatty alcohol polyalkylene glycol ether, also known trivially as fatty alcohol alkoxylate or alkoxylated fatty alcohol, can only be composed of ethylene oxide units (y = 0) or only of propylene oxide units (x = 0). However, the polyalkylene glycol ether may also contain both ethylene oxide units and propylene oxide units. Both the respective proportions and the order of the units (eg alternating or blockwise) can vary here. A non-limiting example of purely ethoxylated fatty alcohol can be based on oleyl or cetyl alcohol: HO- (CH 2 CH 2 O) _n -R with R

or Ci6 with n = 5 for example. Deviations in the base alcohol, type and number of alkoxy units are readily conceivable.

Preferably, the weight fraction of the fatty alcohol polyalkylene glycol ether may be from 1 to 5% by weight, with lower proportions, e.g. B. 1 wt .-%, are particularly preferred. Advantageously, the lubricant composition with 1% by weight of fatty alcohol-polyalkylene glycol ether has a suitable emulsifier balance with sufficiently good emulsifying properties, without negatively influencing the separation behavior in the cleaning system (demulsifying behavior). While too low an emulsifier concentration results in less cleanability of tool, workpiece and machine room, too high concentrations prevent the oil separation in the cleaning system. The glycolic acid alkoxylate alkyl ether alternative to the fatty alcohol polyalkylene glycol ether

(also ether carboxylic acid) has the formula (II)

R ² -0 - [(CH ₂ CH ₂ O) x- (CH ₂ CH (CH 3) O) _y ] -CH 2 -COOH (II)

wherein R ^{2 is} an aliphatic, branched or linear C _6-2 o alkyl or alkenyl radical.

Here, too, purely ethoxylated, purely propoxylated or mixed ethoxylated and propoxylated compounds can be considered, so that x and y are selected from 0 to 10, provided that the sum x + y = 1 to 10. The glycolic acid alkoxylate alkyl ether is preferably a glycolic acid ethoxylate alkyl ether.

Exemplary glycolic acid alkoxylate alkyl ethers are poly (oxy-1,2-ethanediyl), a- (carboxymethyl) -o-hydroxy, Cio-w and Ci ₂ -o-unsaturated alkyl ethers (eg CAS No. 68954-89-2 ), Poly (oxy-1,2-ethanediyl), α- (carboxymethyl) - (yo-hydroxy, C16-18 and cis-unsaturated alkyl ethers (CAS No. 227310-69-2), poly (oxy-1, 2-ethanediyl), a- (carboxymethyl) -u) -hydroxy-octyloxy- (CAS No. 53563-70-5) or poly (oxy-1,2-ethanediyl), a- (carboxymethyl) -u) - hydroxy-hexyloxy, (CAS No. 105391-15-9). The C16-24 aliphatic alcohol used in the lubricant composition of the present invention may be a branched alcohol, preferably a Guerbet alcohol (long-chain, α-position to the primary OH group alkyl-substituted alcohol), such as. For example, 2-hexyl-1-decanol or 2-octyl-1-dodecanol. The latter C ₂ o-alcohol can preferably be used. Such alcohols can be used at lower application temperatures because of the lower pour point and lower tendency to stick due to complete saturation than is possible with natural linear alcohols.

A lubricant composition designed according to the invention can thus consist of only two components, the basic C 16-24-alcohol and the emulsifier. In a further embodiment of the invention, however, it may also be provided that the lubricant composition additionally contains from 0.05 to 5% by weight, based on the total weight of the composition, of fatty acid alkanolamide or alkoxylated fatty acid alkanolamide of the formula (III)

R ^{3 is} - (CO) -NR '- (CH ₂ ) 2-0 - [(CH ₂ CH ₂ O) x- (CH ₂ CH (CH 3) O) _y ] -R "(III) wherein R ^{3 is} an aliphatic, linear or branched C5-23 alkyl or alkenyl radical and R ', R "are independently hydrogen or an aliphatic, linear or branched, substituted or unsubstituted alkyl or alkenyl radical, x and y can each be selected from 0 to 10, so that as above pure ethoxylated, purely propoxylated and mixed ethoxylated and propoxylated compounds are included, in which case the sum x + y can be from 0 (not alkoxylated) to 10. The addition of a fatty acid alkanolamide or alkoxylated fatty acid alkanolamide contributes to an improved corrosion protection effect of the lubricant composition and, due to the emulsifying properties, can positively influence the cleanability of the workpiece or of the machine. Further, a lubricant composition of the present invention may further comprise at least one performance additive selected from a group consisting of

a) sulfurized compounds such as sulfurized olefins, sulfurized esters, sulfurized triglycerides and sulfurized natural ester oils,

b) C12-24 fatty acids,

c) ethoxylated natural oil,

d) KOH saponified beet oil,

e) ethoxylated acidic phosphoric acid ester

includes. Here are some examples that are explicitly meant to be non-limiting:

Non-limiting examples of

a) comprise sulphurised compounds

 sulfurized olefins such as di-tert-dodecyl polysulfides (EC No. 270-335-7), e.g. Di-ferf-dodecyl-trisulfide or di-te / f-dodecyl-pentasulfide,

 sulphurised esters such as fatty acids, vegetable oil, methyl esters, sulfurized (EC No. 276-337-4),

 sulfurized triglycerides / sulfurized natural ester oils, e.g.

 sulphurised rapeseed oil, sulphurised lard oil, sulphurised castor oil etc., b) pure fatty acids, e.g. Oleic acid or the like having chain lengths in the range of C12-24; c) ethoxylated natural oils such as e.g. Castor ethoxylate with 1 to 10 ethylene oxide units, d) KOH saponified rapeseed oil,

e) acidic phosphoric acid ester ethoxylated, e.g. Oleyl alcohol ethoxylate phosphate (CAS No. 39464-69-2).

In this case, a proportion of each performance additive based on the total weight of the composition is a maximum of 15 wt .-%, wherein the proportion of the sum of the performance additives based on the total weight of the composition does not exceed 30 wt .-%. A lubricant composition according to the invention can thus be used for minimum quantity lubrication in metalworking, with residues of the lubricant composition remaining on surfaces of the workpiece and the tool being washable with water.

Claims

1. lubricant composition for minimum quantity lubrication in metalworking,  characterized in that  the composition  0.05 to 5 wt .-% emulsifier, based on the total weight of the composition and  a proportion of an aliphatic C 16- 2 -alcohol which complements 100% of the composition,  wherein the emulsifier is selected from fatty alcohol polyalkylene glycol ethers, glycolic acid alkoxylate alkyl ethers or mixtures thereof. 2. A lubricant composition according to claim 1,  characterized in that  the fatty alcohol polyalkylene glycol ether of the formula (I) R * - [(CH ₂ CH ₂ O) x- (CH ₂ CH (CH 3) O) _y ] -R ¹ (I)  having,  R is an aliphatic, branched or linear C16-18 alkyl or alkenyl radical, and R * is a hydroxyl radical, where x = 0 to 10, y = 0 to 10 and x + y = 1 to 10. 3. Lubricant composition according to claim 1,  characterized in that  the glycolic acid alkoxylate alkyl ether has the formula (II) R ² -0 - [(CH ₂ CH ₂ O) x- (CH ₂ CH (CH 3) O) y] -CH 2 -COOH (II)  having, R ^{2 is} an aliphatic, branched or linear Ce-2o alkyl or alkenyl radical, where x = 0 to 10, y = 0 to 10 and x + y = 1 to 10. 4. A lubricant composition according to at least one of claims 1 to 3, characterized in that the aliphatic Ci6- ₂ 4 alcohol is a branched alcohol, preferably a Guerbet Alcohol, more preferably a C2o-alcohol. 5. Lubricant composition according to at least one of claims 1 to 4, characterized in that  the composition in addition  From 0.05 to 5% by weight, based on the total weight of the composition, of fatty acid alkanolamide or alkoxylated fatty acid alkanolamide of the formula (III) R ³ - (CO) -NR '- (CH ₂ ) 2-0 - [(CH ₂ CH ₂ O) x- (CH ₂ CH (CH 3) O) y] -R "(III)  having, R ^{3 is} an aliphatic, linear or branched Cs-23 alkyl or alkenyl radical, R ', R "is independently hydrogen or an aliphatic, linear or branched, substituted or unsubstituted alkyl or alkenyl radical, and  where x = 0 to 10, y = 0 to 10 and x + y = 0 to 10. 6. Lubricant composition according to at least one of claims 1 to 5, characterized in that  the composition additionally comprises at least one performance additive from the group comprising  a) sulfurized compounds comprising sulfurized olefins, sulfurized esters, sulfurized triglycerides and sulfurized natural ester oils,  b) C12-24 fatty acids,  c) ethoxylated natural oil,  d) KOH saponified beet oil,  e) ethoxylated acidic phosphoric acid ester  includes. 7. A lubricant composition according to claim 6,  characterized in that  a proportion of each performance additive, based on the total weight of the composition, is 15% by weight, based on the total weight of the composition, and a proportion of the sum of the performance additives based on the total weight of the composition is 30% by weight. 8. Use of a lubricant composition according to at least one of claims 1 to 7 for minimum quantity lubrication in metalworking, wherein residues of the lubricant composition remaining on surfaces of the workpiece and the tool can be washed off with water.