Aqueous Composition Comprising Water-Soluble Glycerin-Based Polyalkylene Glycols and Use Thereof

Abstract

The invention relates to aqueous composition comprising water-soluble glycerin-based polyalkylene glycols as synthetic base oils as well as the use of the composition and the glycerin-based polyalkylene glycols as or in metalworking fluids, wherein the glycerin was consecutively alkoxylated in the following order: first with propylene oxide, followed by ethylene oxide and finally with propylene oxide.

Claims

1. A composition comprising water; and at least one water-soluble polyalkylene glycol of the formula (I) ##STR00002## wherein independently of each other R.sub.1 is —(C.sub.3H.sub.6O).sub.x1—(C.sub.2H.sub.4O).sub.y1—(C.sub.3H.sub.6O).sub.z1—H; R.sub.2 is —(C.sub.3H.sub.6O).sub.x2—(C.sub.2H.sub.4O).sub.y2—(C.sub.3H.sub.6O).sub.z2—H; and R.sub.3 is —(C.sub.3H.sub.6O).sub.x3—(C.sub.2H.sub.4O).sub.y3—(C.sub.3H.sub.6O).sub.z3—H; and x1, x2 and x3 are independently of each other a number of 0 to 6; y1, y2 and y3 are independently of each other a number of 0 to 40; and z1, z2 and z3 are independently of each other a number of 0 to 32; and x1+x2+x3 has an average value of from 1 to 4; y1+y2+y3 has an average value of from 2 to 30; and z1+z2+z3 has an average value of from 1 to 25.

2. The composition according to claim 1, wherein independent of each other x1+x2+x3 has an average value of 1.8 to 2.2; y1+y2+y3 has an average value of 2 to 10; and/or z1+z2+z3 has an average value of from 1 to 20.

3. The composition according to claim 1, wherein the water-soluble polyalkylene glycol of formula (I) has independent of each other one or more of the following properties: a pour point according to GB/T 3535 of below −30° C.; a hydroxyl number according to GB/T 7383 of 100 to 300 mg KOH/g; a kinematic viscosity at 25° C. according to GB/T 265 of below or equal to 1.500 cSt; a kinematic viscosity at 40° C. according to GB/T 265 of below or equal to 100 cSt; a kinematic viscosity at 100° C. according to GB/T 265 of below or equal to 10 cSt; a water content equal to or below 0.5 wt.-%; and a molecular weight between 600 and 1,200 g/mol (number average).

4. The composition according to claim 1, comprising 30 to 85 wt.-% water.

5. The composition according to claim 1, comprising 5 to 30 wt.-% of the water-soluble polyalkylene glycol of formula (I).

6. The composition according to claim 1, further comprising at least one alkanolamine.

7. The composition according to claim 1, further comprising 0.1 to 15 wt. % of a carboxylic acid.

8. The composition according to claim 1, wherein the composition comprises no C6 to C16 mono- or di-carboxylic acid.

9. The composition according to claim 1, comprising 0.1 to 0.5 wt.-% of aminoacetic acid sodium salts, and/or 0.1 to 0.5 wt.-% of at least one biocide.

10. The composition according to claim 1, wherein the composition has a pH-value between 7 and 10 at 25° C.

11. The composition according to claim 1, wherein the composition has a surface tension of equal to or below 60 mN/m.

12. The composition according to claim 1, wherein the composition has a contact angle on a metal surface of equal to or below 90°.

13-15. (canceled)

Description

DETAILED DESCRIPTION OF THE INVENTION

[0050] The alkoxylation is preferably carried out in the presence of a base catalyst at a temperature from 120° C. to 180° C. and a pressure of 1 to 10 bar in an agitating or loop reactor. After the reaction of the alkylene oxide with the glycerin starter, an equivalent mole ratio of organic acids can be used to neutralize the base catalyst to an acid value in the range of 0 to 0.3 mg KOH/g. Preferred base catalysts are potassium hydroxide and/or potassium methylate, preferably at a dosage of catalyst in the range of 0.1 to 0.4 wt.-%, relative to the weight of the final end product including the catalyst.

[0051] The most preferably organic acids are one or more from glacial acetic acid and lactic acid. The final neutralized salt can be kept in the product or removed by adsorption and filtration technologies well-known by experienced experts in this field.

[0052] The glycerin alkoxylate may alternatively be produced by reaction with the alkylene oxide over a suitable alkoxylation catalyst. Suitable catalysts are those derived from the Group IA and Group IIA metals including potassium, sodium, calcium, magnesium; typically, the metal is present as a base salt and notably its hydroxide. Certain catalyst species are recognized in their ability to produce narrow range alkoxylates having a reduced polydispersity index. A polydispersity index (PDI) of alkoxylated glycerin is defined as the ratio of weight average EO moles to number average. Use of catalyst derived from Group IIA metals, especially calcium or magnesium are typically recognized as being narrow range ethoxylation catalysts. In contrast catalyst derived from Group IA metals, such as potassium hydroxide are generally recognized as giving broad range ethoxylated alcohols where the polydispersity index can be 1.37 or higher.

[0053] According to one embodiment, the glycerin alkoxylate is produced by reaction over a narrow range alkoxylation catalyst, more preferably over a calcium-containing ethoxylation catalyst providing an alkoxylated glycerin with a polydispersity index of 1.35 or less, preferably 1.3 or less, more preferably 1.25 or less. Exemplary of a suitable calcium-containing alkoxylation catalysts is the proprietary NOVEL catalyst developed by Sasol (USA) Corporation.

[0054] Without being bound to this theory it is assumed that the PO-building blocks directly attached to the glycerin lead to a more balanced distribution of the subsequent EO-addition as they equalize the difference in reactivity between the —OH respectively the EO of the primary and secondary alcohol groups of the glycerin.

[0055] The water-soluble polyalkylene glycol of formula (I), has independent of each other one or more of the following properties: [0056] a pour point according to GB/T 3535 of below −30° C.; [0057] a hydroxyl number according to GB/T 7383 of 100 to 300 mg KOH/g, preferably 150 to 270 mg KOH/g; [0058] a kinematic viscosity at 25° C. according to GB/T 265 of below or equal to 1500 cSt, preferably below 300 cSt; [0059] a kinematic viscosity at 40° C. according to GB/T 265 of below or equal to 100 cSt; [0060] a kinematic viscosity at 100° C. according to GB/T 265 of below or equal to 10 cSt; [0061] a water content equal to or below 0.5 wt.-%; and [0062] a molecular weight between 600 and 1200 g/mol (number average).

[0063] In a preferred embodiment the composition comprises 5 to 30 wt.-% of the water-soluble polyalkylene glycol of formula (I).

[0064] The composition may further comprise at least one alkanolamine, preferably 5 to 25 wt.-% of at least one alkanolamine. The alkanolamine is preferably selected from the group of monoethanolamine, triethanolamine and/or monoisopropanolamine.

[0065] The composition may further comprise boric acid, triazine tricarboxylic acid and/or phosphoric acid and any salts thereof, for example sodium salts, preferably 0.1 to 10 wt. %.

[0066] The composition may further comprise at least one carboxylic acid, according to one embodiment 0.1 to 15 wt. %, preferably 0.5 to 10 wt.-%. According to one embodiment of the invention the composition comprises no carboxylic acid. The carboxylic acid may be a C6 to C14 mono- or di-carboxylic acid such as isononanoic acid, 2-butyloctanoic acid, neodecanoic acid, 1,12-dodecanedioic acid. The acid is usually added in an amount until the solutions clears up and the composition has a pH-value between 7 and 10, preferably between 8 to 10 measured at 25° C.

[0067] The composition may also comprise 0.1 to 0.5 wt.-% of aminoacetic acid sodium salts, such as tetra sodium EDTA (ethylenediaminetetraacetic acid) and/or 0.1 to 0.5 wt.-% of at least one biocide, such as BUSAN® 77 (Poly[oxyethylene(dimethyliminio)-ethylene(dimethyliminio)ethylene dichloride]).

[0068] The amount of water used is preferably between 30 to 85 wt.-%. According to one embodiment the remainder of the composition is demineralized water.

[0069] Further the composition preferably has a pH-value between 7 and 10, preferably 8 and 10, each at 25° C.

[0070] Preferably the surface tension of the composition is equal to or below 60 mN/m and/or the contact angle on a metal surface is equal to or below 90°.

[0071] The cloud point according to GB/T 5559 of 1 wt.-% of the water-soluble polyalkylene glycol of the formula (I) in the metalworking fluid composition with water is preferably above 80° C.

[0072] This high cloud point relates to a low dosage of monoacid (e.g. isononanoic acid) required to solubilize the polyalkylene glycol of formula (I) in water, preferably no carboxylic acid such as nonanoic acid is presence of acid.

[0073] Another advantage of the composition according to the invention is that the addition of acids often causes smell and foam, especially during extended use times of the metalworking fluid composition. This can be avoided or at least minimized. It is desirable to waive the use of acids.

[0074] The composition may be used as a metalworking fluid, showing reduced foaming, a low surface tension and a low contact angle on metal surfaces.

[0075] Further the alkoxylated glycerin of formula (I) reduces the tapping torque and increases the cloud point of the composition. In addition, due to the lower amount of carboxylic acid used, the smell of the composition is more pleasant.

[0076] More preferably the polyalkylene glycol is used to reduce the surface tension of the compositions to 60 mN/m and below and/or the contact angle on a metal surface to 90° and below.

[0077] The water-soluble PAGs of the invention can be used as a fully-synthetic base oils in metalworking fluid compositions. Next to the PAGs and water the composition when used as a metalworking fluid may comprise the above_mentioned acids, amines and other additives.

[0078] The metalworking fluids of the present invention are for example used for processes with high shear rates, such as cutting, grinding and punching of metal pieces. This also includes for example the cutting of silicon wafers.

[0079] A further use is as a quenching fluid in metalworking. In the above context quenching is the rapid cooling of a workpiece in an oil composition comprising as base oil the PAGs according to the invention.

[0080] The use of the compositions as metalworking fluids and the use of the polyalkylene glycols of formula (I) in metalworking fluids and or metalworking processes is also claimed.

[0081] Typical metal alloys used in metalworking processes applying the metalworking fluid according to the invention are aluminum alloys of the type 7075, 6061, 5053 and LY 12, red copper, cast iron and iron alloys such as stainless steel.

Measurement Techniques

[0082] Pour points are determined according to GB/T 3535 (Chinese equivalent to ASTM D 97), the kinematic viscosity at different temperatures (e.g. at 25, 40 and 100° C.) according to GB/T 265 (equivalent to ISO 3104), the cloud point of 1 wt.-% solution in water according to GB/T 5559 (equivalent to ISO 1065) and the hydroxyl number (mg KOH/g) according to GB/T 7383 (equivalent to ISO 4326).

[0083] The further characteristics of a metalworking fluid such as foaming properties, surface tension, contact angle on metal surfaces, sedimentation and lubricity are be measured according to the following methods.

[0084] The foaming behavior can be tested by putting 50 ml of a diluted metalworking fluid (usually to 3 to 5 wt.-%) in a 100 ml-measuring cylinder, shaking the cylinder for 1 minute with one hand 100 to 110 times and thereafter and determining the volume of the formed foam in ml as well as the time required until the foam completely decayed again.

[0085] Foam is undesirable in metal processing as it impacts the visibility and extends the volume of the liquid. Therefore, the foam formation (measured as provided above) should be below or equal to 20 ml and the foam decay equal to or below 10 seconds.

[0086] A broadly recognized method to determine the foaming is the CNOMO foam test D 65 5212, in which the diluted metalworking fluid to be examined is introduced up to the 1000 ml mark in a 2000 ml graduated cylinder, circulated at 250 l/h±10 l/h for 5 hours±5 minutes, while the temperature of the liquid is kept at 23° C.±2° C. using the water circulation. Afterwards the volume of foam formed (in ml) both during the test and the foam remaining after 15 minutes at rest are determined as well as the appearance grading of the liquid (0=no variation to 5=general soiling of the installation) and the flow at the end of the test (in l/h).

[0087] The grading is reported in the following way: Time/foam volume/foam volume after 15 min/appearance of the liquid/flow at the end of the test. For example, the grading 300/500/0/0/250 means 500 ml foam volume after 5 hours (300 min) test, no foam after 15 minutes after the end of the test, the initial appearance is not modified and the flow at the end of the test was 250 l/h.

[0088] The surface tension of the diluted metalworking fluid can be determined according to ASTM D 3825.

[0089] The contact angle on a metal surface such as cast iron can be determined according to ASTM D 5725. The surface tension is preferably below 60 mN/m and the contact angle on cast iron below 90°.

[0090] Wear from the metal processing should separate from the metalworking fluid as quick as possible, so that the abrasive wear can be removed effectively from the metalworking fluid so that the metalworking fluid can be recirculated for further use. A method to test this property of used metalworking fluid is to add 5 wt.-% carbon powder to a defined volume of the metalworking fluid or a diluted metalworking fluid, stir the mixture for 5 minutes and observe the sedimentation of the carbon powder at the bottom of a measuring cylinder over time (e.g. after 60 minutes).

[0091] The smaller the volume of the phase of the diluted fluid composition mixed with the carbon powder, the better the sedimentation and the more effective the separation. An effective separation allows a more effective recycling of the water in the metal processing.

[0092] The lubricity of the diluted metalworking fluid can be determined with or based on the so-called Tapping Torque Test according to ASTM D 5619 (Comparing Metal Removal Fluids Using the Tapping Torque Test Machine). The torque required to tap a thread in a blank specimen nut while lubricated with an oil composition is measured and compared with the torque required to tap a thread in a blank specimen nut while lubricated with a reference fluid. The ratio of the average torque values of the reference oil to the oil composition tested, when using the same tap, is expressed as the percent efficiency of the fluid. One can also compare the mean value of the maximum torque.

[0093] The lower the torque, the higher the efficiency of the fluid. For the reported torque values, the used metal alloy, test speed and fluid concentration need to be disclosed.

Examples

[0094] Different polyalkylene glycols based on glycerin as alcohol were produced (see table 1) and compared to commercially available block ethylene oxide-propylene oxide copolymers from BASF (SYNATIVE® RPE 1720 and 1740, see table 2).

[0095] The alkoxylation of the glycerin was conducted with KOH as catalyst and if applicable the propoxylation and ethoxylation were done subsequently, so that defined building blocks were attached to the triole. The propylene- and ethylene oxide were consecutively dosed in the according equivalents (e.g. 2 mol eq. for 2 mol PO, 5 mol eq. for 5 EO), but the reaction does of course take place in a statistically manner, which means that in reality the molecules have a statistically distributed degree of alkoxylation for each of the building blocks. That is why the final number of building blocks given for the different products can only be an average over all molecules produced.

TABLE-US-00001 TABLE 1 Synthesised glycerin-based polyalkylene glycols Molecular weight Compound Structure [g/mol] 1 Comp. Glycerin + 7.5 EO 420 2 Comp. Glycerin + 7 EO + 10 PO 980 3 Comp. Glycerin + 18 EO + 37 PO 3000 4 Comp. Glycerin + 10 PO 671 5 Comp. Glycerin + 2 PO + 7 EO 520 6 Inv. Glycerin + 2 PO + 7 EO + 3 PO 690 7 Inv. Glycerin + 2 PO + 7 EO + 7 PO 920 8 Inv. Glycerin + 2 PO + 7 EO + 10 PO 1100 9 Comp. Glycerin + 5 PO + 7 EO + 7 PO 1100

TABLE-US-00002 TABLE 2 Properties of commercial and synthesised polyalkylene glycols Hydroxyl Pour Cloud Viscosity Viscosity Viscosity Water number point point @25° C. @40° C. @100° Compound content [mg KOH/g] [° C.] [° C.] [cSt] [cSt] [cSt] RPE 1740 <0.5% 42 9 48.6 600 300 50 RPE 1720 <0.5% 39 −32 38.1 450 230 45 1 <0.5% 400-420 <−10 >95 210 100 10 2 <0.5% 170-200 <−30 >90 230 105 11 3 <0.3% 56-75 <−30 43.9 390 180 30 4 <0.5% 250-270 <−10 >95 250 100 10 5 <0.5% 280-300 <−30 >90 220 105 10 6 inv. <0.5% 240-270 <−30 >90 220 100 10 7 inv. <0.5% 180-210 <−30 82.0 225 80 10 8 inv. <0.5% 150-170 <−30 80.0 230 80 10 9 <0.5% 150-170 <−30 80.0 230 80 10

[0096] The polyalkylene glycols of table 2 were used in the metalworking fluid composition according to the below formulation (all in wt.-%).

TABLE-US-00003 Tetra sodium EDTA 0.30%   Monoethanolamine 5% Triethanolamine 15%  Boric acid 5% 1,12-Dodecanedioic acid 2% COMPOUND 1 to 9 or 10%  RPE 1740/1720 IRGACOR ® L 190 Plus 5% (Corrosion inhibitor) Busan 77 (Biocide) 0.30%   Isononanoic acid to clear Demineralized water ~100 Amount of Compound isononanoic acid RPE 1740 5.7 wt.-% RPE1720 9.5 wt.-% 1 0 wt.-% 2 1.5 wt.-% 3 9.2 wt.-% 4 3.6 wt.-% 5 0 wt.-% 6 inv. 0 wt.-% 7 inv. 0 wt.-% 8 inv. 2.8 wt.-% 9 2.2 wt.-%

[0097] The compositions according to the invention required significantly less or no addition of isononanoic acid, which not only reduces the formation of foam, but also the formation of smell, especially during the processing of the metalworking fluid.

[0098] The metalworking fluids were diluted to 3 wt.-% in distilled water, with a content of Calcium and Magnesium of 100 ppm and the properties of these formulations were determined (see table 3) according to the measurement techniques described above.

[0099] The foam creation grading according to CNOMO was the same in all cases, except the volume of foam directly after the 5 hours of the test. Therefore, only this value (X) was reported in table 3. The other values were 300/X/0/0/125.

[0100] It can be clearly seen that the metalworking fluids according to the invention made with the glycerin-based polyalkylene glycols 6, 7 and 8 showed a much lower foam formation, a quicker foam decay, a lower tapping torque, a comparable surface tension and contact angle and a lower sedimentation volume compared with commercial EO/PO-block copolymers (1740, 1720), glycerin-EO (1), glycerin-EO-PO (2, 3), glycerin-PO (4), glycerin PO-EO (5) and glycerin PO-EO-PO outside the claimed range (9). These properties qualify them as highly efficient PAG compositions for metalworking applications.

[0101] The composition according to the invention when used as a metal working fluid provides for efficient sedimentation or settling properties and can be easily recycled.

TABLE-US-00004 TABLE 3 Properties of metalworking fluid compositions. Foam Foam volume Contact creation according Surface Angle on Tapping [ml]/ to CNOMO tension cast iron Torque defoaming D 65 [mN/m] [°] [Ncm] Sedimentation time 5212 ASTM D ASTM D ASTM D volume [s]* [ml] 3825 5725 5619 [ml].sup.# 1740 25 ml/9 sec  170 43.7 75.42 184.6 76 1720 18 ml/8 sec  160 40.1 71.15 189.2 78 1 20 ml/9 sec  160 67.4 92.70 197.0 42 2 37 ml/12 sec 180 49.0 81.21 177.7 70 3 27 ml/13 sec 170 41.1 73.60 187.5 75 4 36 ml/15 sec 180 48.4 76.43 191.3 74 5  30 ml/170 sec 180 64.1 89.71 184.9 51 6 inv. 6 ml/5 sec 100 59.3 85.90 178.5 70 7 inv. 20 ml/7 sec  160 53.8 85.63 177.7 68 8 inv. 17 ml/8 sec  160 46.7 79.60 178.7 68 9 22 ml/10 sec 160 49.7 86.48 191.8 66 *Tested by shaking 50 ml of the metalworking fluid in a 100 ml cylinder for 1 min and determine the volume of the foam afterwards as well as the time required until the foam completely decayed again .sup.#Sedimentation of 5 wt.-% carbon powder at the bottom of a 100 ml cylinder filled and mixed by stirring with diluted metalworking fluid

[0102] In addition, the water-soluble polyalkylene glycols as used in the composition according to the invention show high cloud points, which is a property well sought after in the metal working fluid technology area. Such higher cloud points are indicative for an increase in the solubility of the base oils in alkaline metalworking fluid compositions. This allows a significant reduction in the amount of monocarboxylic acid solubilisers, where according to a preferred embodiment of the invention monocarboxylic acids are not at all used in the composition or metal working fluid according to the invention. This does not only reduce the foaming problems in metalworking fluid compositions associated with the monocarboxylic acids, but also reduces the odour problems caused by the monocarboxylic acids, which is particularly important in the practical use of metalworking fluids.