Patent Description:
Water based lubricants are commonly used as metalworking fluids such as cutting fluids. These are often described as soluble oils, semisynthetic and synthetic metalworking fluids. A key function is to cool and lubricate the interface between the cutting tool and the machined part. In the production engineering industry, there continues to be a trend to higher machining speeds. The impact on the fluid is that foaming is more prevalent. Thus there is a need for aqueous based metalworking fluids that offer lower and superior foaming performance. Water based metalworking fluids, and particularly synthetic metalworking fluids, can contain a polyalkylene glycol at levels of between <NUM> and <NUM>% by weight of the fluid in use.

Another application for water based lubricant is in gear oils. Water based gear oils are effective at cooling the interface between the gears and in removing heat. Since gear oils result in turbulence and churning of the fluids, foaming can occur. Water based gear lubricants are increasingly used for their environmental benefits over hydrocarbon lubricants since they offer higher levels of biodegradability and are perceived as a more sustainable solution. It is desirable that water based gear lubricants offer low foaming performance. Water based gear lubricants can contain a polyalkylene glycol at levels of <NUM>-<NUM>% as a thickening agent and lubricity additive.

A further application is water based hydraulic fluids. These are used in the steel and aluminium processing industries for their fire resistance properties and also in the mining industry. The PAGs used in these formulations are at typical treat levels of <NUM>-<NUM>% by weight. In the oil and gas industry, water based subsea hydraulic fluids containing PAGs are used to control the flow of oil deep underwater. Occasionally these fluids are leaked or released into the ocean. Therefore, it is desirable to have biodegradable hydraulic fluids.

Many of these types of hydraulic fluids used in equipment contain water, a glycol and a relatively high molecular weight polyalkylene glycol (PAG) as a thickener or rheology modifier. These three components typically represent more than <NUM>% by weight of a hydraulic fluid composition (with the remainder being an additive package comprising corrosion inhibitors, foam control additives, air release additives, friction modifiers and dyes) and it is desirable that each of these components offers a high degree of biodegradability so that the final formulation offers a high degree of biodegradability. The glycols used can be, for example, ethylene glycol, diethylene glycol, and propylene glycol and are readily biodegradable. The PAGs are typically random copolymers of ethylene oxide (EO) and propylene oxide (PO) (typically <NUM>,<NUM>-propylene oxide) having molecular weights of about <NUM>,<NUM>/mol or higher. These high molecular weight PAGs do not have the desired degree of biodegradability and have very low biodegradability. An example would be UCONTM <NUM>-H-<NUM>,<NUM> from the Dow Chemical Company.

Lower molecular weight PAGs are known to be more biodegradable but do not have sufficient thickening efficiency in a water/glycol base fluid for the desired applications. <CIT> relates to hydraulic fluids having biodegradable polyalkylene glycol rheology modifiers useful in subsea applications. <CIT> relates to a high-concentration polymer polyol and method for manufacturing the same.

Thus, it is desired to have a hydraulic fluid composition which has a high degree of biodegradability while also maintaining the desired rheology properties for the fluid. Moreover it would be preferable to include a biodegradable polyalkylene glycol at a treat level of less than <NUM>% by weight of the total weight of the composition to help keep the formulation costs low. Additionally it is desirable that the formulation exhibits relatively low amounts of foaming.

Disclosed herein are compositions comprising water and one of more polyalkylene glycols in which the polyalkylene glycol is present at levels of <NUM> to <NUM>%.

In one aspect, the present invention provides a composition comprising <NUM> to <NUM> weight % water, <NUM> to <NUM> weight% of a glycol selected from ethylene glycol, diethylene glycol, triethylene glycol, tetra ethylene glycol and propylene glycol, <NUM> to <NUM> weight % of a polyalkylene glycol, and <NUM> to <NUM>% of additives based on total weight of the composition wherein the polyalkylene glycol has a - molecular weight of no more than <NUM>/mol, as measured by ASTM D4274, and is characterized in that it is an oxyethylene/oxypropylene block copolymer having a weight percent of oxyethylene of at least <NUM>% based on total weight of the copolymer, and further characterized that the composition has an allyl content of less than <NUM>µeq allyl per gram of polyalkylene glycol (µeq /g).

Also disclosed herein is a method for making an oxyethylene/oxypropylene block copolymer comprising the steps of forming a first intermediate comprising an oxypropylene block in the presence of a Double Metal Cyanide ("DMC") catalyst (in the substantial absence of potassium hydroxide ("KOH") catalyst) and a second step of forming the block copolymer by forming one or more oxyethylene blocks onto the first intermediate in the presence of a KOH catalyst.

Also disclosed herein is a composition comprising water, a glycol, and a polyalkylene glycol having a biodegradability of at least <NUM>% as determined using OECD 301F wherein the composition has a kinematic viscosity of at least <NUM> mm2/sec at <NUM>.

The composition disclosed herein comprises a polyalkylene glycol and water.

The polyalkylene glycol is preferably characterized in that it is biodegradable. Specifically, the biodegradability when measured using OECD 301F should be at least <NUM>%, or at least <NUM>% or at least <NUM>% or at least <NUM>%.

The polyalkylene glycol has a molecular weight of no more than <NUM>/mol, or no more than <NUM>/mol, or no more than <NUM>/mol but at least <NUM>/mol, or at least <NUM>/mol, or at least <NUM>/mol as measured by ASTM D4274.

The polyalkylene glycol is characterized in that it is a block copolymer of ethylene oxide ("EO") and propylene oxide ("PO") (especially <NUM>,<NUM>-propylene oxide). The block formed from ethylene oxide is also referred to herein as oxyethylene or the oxyethylene block. The block formed from the propylene oxide is also referred to herein as oxypropylene or the oxypropylene block. The weight percent of ethylene oxide is greater than <NUM>% or greater than <NUM>% based on total weight of ethylene oxide and propylene oxide used in making the polyalkylene glycol. According to one embodiment, the weight percent of ethylene oxide is no greater than <NUM>%, or no greater than <NUM>% or no greater than <NUM>%. The block copolymer may be linear or branched.

The polyalkylene glycol composition is further characterized in that it has an allyl content of less than <NUM>µeq/g, alternatively,<NUM>µeq/g or less or less than <NUM>µeq/g. Less allyl content is generally preferred, but some allyl can be tolerated such that the polyalkylene glycol composition may have zero µeq allyl per gram or at least <NUM>µeq/g. Allyl alcohol is believed to form when PO isomerizes when KOH is used as a catalyst. It has been observed that when DMC is used as the catalyst when making PO blocks, the resulting reaction mixture exhibits lower unsaturation levels suggesting less allyl formation. It is believed that allyl alcohol, when present can act as a secondary initiator and competes with mono-propylene glycol as the primary initiator, to form an allyl-PO block which is further ethoxylated to form an allyl-PO-EO diblock. It is further believed that this component likely causes increased foaming, as it appears structurally similar to pseudo-fatty alcohol ethoxylates which are known to be high foaming surfactants. Other unsaturation, such as propenyl unsaturation, may also exist in the composition. Preferably the total unsaturation is <NUM>µeq/g or less, <NUM>µeq/g or less, <NUM>µeq/g or less, <NUM>µeq/g or less or less than <NUM>µeq/g.

Allyl content can be determined using Nuclear Magnetic Resonance (NMR) spectroscopy according to the following method: Up to <NUM> gram of the sample is dissolved in <NUM> deuterated acetone (acetone-d6) (containing chromium (III) acetylacetonate as relaxation agent) (less than <NUM> grams of the sample may be used to produce clear homogeneous solutions for less soluble materials. A quantitative 13C NMR spectrum is acquired using a <NUM> probe head on a <NUM> spectrometer. Additional proton a 2D spectra were acquired in acetone-d6 (<NUM>/mL) using a <NUM> probe head on a <NUM> spectrometer. Total unsaturation level for each product was also measured using ASTM D4671. This measures all unsaturation in the polyalkylene glycol such as allyl and propenyl.

Also disclosed herein is a method for making an oxyethylene/oxypropylene block copolymer comprising the steps of:.

In certain embodiments, the block copolymer may have an ABA structure, where A is an oxyethylene based block and B is an oxypropylene based block. For example, <NUM>,<NUM>-propylene oxide is reacted onto a diol initiator, for example <NUM>,<NUM>-propylene diol, to make an oxypropylene block (B). Thereafter ethylene oxide is added to synthesize a block of oxyethylene (A) and the final polymer has an ABA structure. A linear ABA is formed when a diol initiator such as ethylene glycol, <NUM>,<NUM>-propylene glycol, <NUM>,<NUM> butylene glycol and neopentyl glycol is used. A diol initiator has two hydroxyl groups in the structure which are the sites for alkoxylation to synthesize the block copolymer. A branched structure is formed when a triol initiator is used. Glycerol and trimethylolpropane are preferred examples of a triol initiator and therefore these initiators contain three hydroxyl groups. For example, <NUM>,<NUM>-propylene oxide is reacted on to the triol initiator (e.g. glycerol) to make three oxypropylene blocks (B) on the three hydroxyl groups of the initiator to form an i-(B)<NUM> intermediate structure. Thereafter ethylene oxide is added to synthesize three blocks of oxyethylene (A) on each B block and the final polymer has an i-(BA)<NUM> structure where i is the initiator (glycerol). Trimethylolpropane is an example of another triol based initiator.

Another branched structure is formed when a tetrol initiator is used. Pentaerythritol is an example of a tetrol initiator and contains four hydroxyl groups. For example, <NUM>,<NUM>-propylene oxide is reacted on to the tetrol initiator (e.g. pentaerythritol) to make four oxypropylene blocks (B) on each hydroxyl of the initiator and having an intermediate structure of i-(B)<NUM>. Thereafter ethylene oxide is added to synthesize four blocks of oxyethylene (A) and the final polymer has an i-(BA)<NUM> structure where i is the initiator (pentarythritol). Even higher initiators can be used, such as sorbitol.

Preferred DMC catalysts include complexes of zinc hexacyanocobaltate (III). Any amount of DMC catalyst which is effective to produce the desired first intermediate in a reaction with the initiator and PO can be used. The preferred DMC catalyst level is <NUM>-50ppm of the total amount of the polyalkylene glycol intermediate. DMC catalyst levels across the range <NUM>-100ppm can advantageously be used. Preferred temperatures for alkoxylation with PO are from <NUM> to <NUM>.

Similarly, while any amount of KOH which is successful in producing the desired ABA polyalkylene glycol can be used, preferred KOH catalyst levels for the step of ethoxylating the intermediate are <NUM>-2500ppm of the total amount of polyalkylene glycol. It is believed that at least catalyst levels across the range <NUM>-4000ppm can be suitably used. Preferred temperatures for ethoxylation are from <NUM> to <NUM>.

According to certain embodiments, the ABA structure is EO block-PO block-EO block represented by formula I
<CHM>
wherein a' and a" are independently in each occurrence an integer of <NUM> to <NUM> provided that a'+a" is at least <NUM> and no more than <NUM>, and b is an integer of from <NUM> to <NUM>.

According to certain water based hydraulic composition embodiments, the amount of the polyalkylene glycol is at least <NUM>%, or at least <NUM>%, or at least <NUM> % by weight based on total weight of the composition. According to certain embodiments the amount of polyalkylene glycol is no more than <NUM>%, or no more than <NUM>% or no more than <NUM>% by weight based on total weight of the composition.

The amount of water is at least <NUM>%, or according to certain embodiments, at least <NUM>% or at least <NUM>% or at least <NUM>% by weight based on total weight of the composition. According to certain embodiments, the amount of water is no more than <NUM>% or no more than <NUM>% or no more than <NUM>% by weight based on total weight of the composition.

In addition to the polyalkylene glycol and water, the compositions of the present invention may also include an amount of glycol, particularly when the compositions are targeted for use in hydraulic fluids. The glycol is selected from ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol and <NUM>,<NUM>-propylene glycol. Mixtures of glycols may also be used. According to one embodiment the glycol is ethylene glycol or diethylene glycol. In fact use of the polyalkylene glycol block copolymers (especially an EO block-PO block-EO block PAG, i.e. EO-PO-EO PAG) with ethylene glycol or diethylene glycol shows an unexpected synergistic effect on increasing the viscosity.

The amount of the glycol, when present according to certain embodiments can advantageously be from <NUM>% or <NUM>% by weight based on total weight of the composition. The amount of glycol according to certain embodiments is no more than <NUM>% or no more than <NUM>% by weight based on total weight of the composition.

Another optional component of the composition is an additive package. The additive package may have one or more additives selected from corrosion inhibitors (e.g. ferrous or vapor phase), lubricity aids, anti-foaming agents, air release additives anti-microbials, and dyes. The cumulative amount of the additives according to an embodiment is no more than <NUM>% by weight based on total weight of the composition.

The hydraulic composition according to certain embodiments meets one of ISO-<NUM>, <NUM> and <NUM> viscosity grades (ISO is International Standards Organization) and therefore has typical kinematic viscosities at 40oC of about <NUM>, <NUM> and <NUM> mm2/sec (cSt) respectively. The composition according to certain embodiments has a kinematic viscosity at 40oC greater than <NUM> mm2/sec as measured by ASTM D7042.

The compositions according to the present invention also exhibit reduced foaming behavior when compared to similar compositions having higher allyl content. Foaming behavior can be evaluated according to ASTM D1173: Standard Test Method for Foaming Properties of Surface-Active Agents, using deionized water at ambient temperature. Preferably, the compositions of the present invention may be characterized by exhibiting an initial foam height of less than <NUM>, or <NUM> or <NUM> at <NUM>% by weight concentration and/or a foam height of less than <NUM>, <NUM> or <NUM> after <NUM> minutes as determined according to ASTM D1173.

The compositions of the present invention feature polyalkylene glycol components which are similar to those presented in <CIT>, except for the allyl content. It is therefore believed that the present polyalkylene glycol components will exhibit similar biodegradability traits as those presented in this document, that is, the biodegradability when measured using OECD 301F is expected to be at least <NUM>%, or at least <NUM>% or at least <NUM>% or at least <NUM>%.

A PO block initiator is prepared as follows: Experiment is carried out on a five liter stainless steel reactor which is temperature controlled via an external thermostatic control unit. The oxide dosing system is controlled by weight and limited by a maximum pressure in the reactor of <NUM> MPag (<NUM> barg). The reactor is operated through CAMILE TG software.

The required amount of Polypropylene glycol P400 starter (with an average molecular weight of <NUM>/mol) (<NUM> gram) and <NUM> milligram of a DMC catalyst which can be obtained from Bayer AG under the trade name Arcol™ Cat <NUM>, is charged into the reactor at <NUM>. Arcol™ Cat <NUM> is reported to be a zinc hexacyanocobaltate (III) tertiary butyl alcohol/propylene glycol complex with a molecular formula of C29H52Co2N12O6Zn3. The reactor is flushed extensively with nitrogen and vacuum is applied while mixing at <NUM> rpm to a dry mixture. Next the reactor content is brought up to <NUM> and after reaching this temperature <NUM>% of the total PO amount is fed for activation (<NUM> gram PO). After activation, the remaining <NUM> grams of PO is fed over a period of <NUM> hours and <NUM> minutes. After a digest period of <NUM> minutes, the reactor content is cooled to <NUM> and vacuum is applied. After approximately <NUM> minutes the reactor content was taken out of the reactor.

Experiments to form triblock polyalkylene glycols are carried out on a <NUM> liter stainless steel reactor which is temperature controlled via an external thermostatic control unit. The oxide dosing system is controlled by weight and limited by a maximum pressure in the reactor of <NUM> MPag (<NUM> barg). When the desired amount of oxide is fed, the oxide feeding is automatically stopped.

For Example <NUM>, <NUM> gram of an Initiator as described above and <NUM> gram of <NUM> wt % aqueous KOH are charged into the reactor at room temperature. In order to limit any discoloration due to oxidation of the initiator in the presence of the base catalyst, the reactor is flushed extensively with nitrogen. Next the reactor content is brought to <NUM> while mixing at approximately <NUM> rpm. The water is removed from the starter/catalyst mixture by applying <NUM> kPa (<NUM> mbar) vacuum. After <NUM> hour at reduced pressure, a sample is taken from the reactor content and the water content is determined by titration (<NUM> ppm of water was measured). What remained in the reactor (<NUM> gram Initiator, <NUM> gram KOH equivalent (403ppm) and <NUM> gram of water) is brought to about <NUM> kPa (<NUM> bar) with nitrogen. Next the temperature of the reactor mixture is increased to <NUM> while mixing at <NUM> rpm. After reaching this temperature <NUM> gram EO is fed over a period of <NUM> hours and <NUM> minutes. After a digest period of <NUM> hours the reactor content is cooled to about <NUM> and <NUM> gram magnesium silicate is added to absorb the potassium catalyst. After approximately <NUM> minutes of mixing, the reactor content is taken out of the reactor and filtered using a Buchner funnel with a paper filter type <NUM> from Sartorius Stedim Biotech until the product is clear. The filtered product has a total unsaturation level of <NUM> meq/g (i.e., <NUM>µeq/g) an allyl level of <<NUM>µeq/g and a <NUM>% cloud point of <NUM>-<NUM> using ASTM D2024. The product has a molecular weight of <NUM>/mol using ASTM D4274, a kinematic viscosity at <NUM> of <NUM> mm2/sec and a kinematic viscosity at <NUM> of <NUM> mm2/sec using ASTM D7042. The PAG contains approximately <NUM>% by weight of oxyethylene as determined by NMR.

For Example <NUM>, <NUM> gram of an Initiator as described above and <NUM> gram of <NUM> wt % KOH are charged into the reactor at room temperature. In order to limit any discoloration due to oxidation of the initiator in the presence of the base catalyst, the reactor is flushed extensively with nitrogen. Next the reactor content is brought to <NUM> while mixing at approximately <NUM> rpm. The water is removed from the starter/catalyst mixture by applying 3kPa (<NUM> mbar) vacuum. After <NUM> minutes at reduced pressure, a sample is taken from the reactor content and the water content is determined by titration (<NUM> ppm of water was measured). What remained in the reactor (<NUM> gram Initiator, <NUM> gram KOH equivalent and <NUM> gram of water) is further dried by applying again <NUM> kPa (<NUM> mbar) vacuum for an additional <NUM> hour and <NUM> minutes. A sample is taken and the water content was determined by titration to ne <NUM> ppm water. What remained in the reactor (<NUM> gram Initiator, <NUM> gram KOH equivalent (<NUM> ppm) and <NUM> gram of water) is brought to about <NUM> kPa (<NUM> bar) with nitrogen. Next the temperature of the reactor mixture is increased to <NUM> while mixing at <NUM> rpm. After reaching this temperature <NUM> gram EO is fed over a period of about <NUM> minutes. After a digest period of <NUM> hours and <NUM> minutes the reactor content is cooled to about <NUM> and <NUM> gram magnesium silicate is added to absorb the potassium catalyst. After approximately <NUM> minutes of mixing, the reactor content is taken out of the reactor and filtered using a Buchner funnel with a paper filter type <NUM> from Sartorius Stedim Biotech until the product is clear. The filtered product has a total unsaturation level of <NUM> meq/g (i.e., <NUM>µeq/g), an allyl level of <<NUM>µeq/g and a <NUM>% cloud point of <NUM>-<NUM> using ASTM D2024. It has a molecular weight of <NUM>/mol using ASTM D4274, a kinematic viscosity at <NUM> of <NUM> mm2/sec and a kinematic viscosity at <NUM> of <NUM> mm2/sec using ASTM D7042. The PAG contains approximately <NUM>% by weight of oxyethylene.

The foaming properties of Example <NUM> and Example <NUM> along with comparative Example <NUM> (an ABA polyalkylene glycol (EO-PO-EO) made using only KOH catalyst for the B block and KOH for the A blocks, and having a total unsaturation level of <NUM> meq/g (<NUM>µeq/g) with an allyl level of <NUM>µeq/g) were evaluated according to ASTM D1173 but at ambient temperature (<NUM>) instead of the recommended temperature of <NUM> per the method: Comparative Example <NUM> has a molecular weight of <NUM>/mol, a kinematic viscosity at <NUM> of <NUM> mm2/sec and a kinematic viscosity at <NUM> of <NUM> mm2/sec and has an oxyethylene content of <NUM>% and an oxypropylene content of <NUM>% by weight of the polymer. Standard Test Method for Foaming Properties of Surface-Active Agents. , both method <NUM> and method <NUM> as follows:.

Prepare <NUM>% aqueous solution of the test polymer using deionized water. Rinse the walls of the receiver with <NUM> of the test solution, using a pipet and after draining to the bottom of the receiver, adjust the stopcock so that the level of the solution in the receiver is exactly at the <NUM>-mL mark. The receiver is a chemically resistant glass tube having an internal diameter of <NUM> with one end constricted and sealed to a straight bore, standard taper No. <NUM> stopcock having a <NUM> bore and <NUM> stem. The receiver contains graduation marks which can show the volume of fluid in the receiver. Further details are described in the ASTM procedure. The receiver is mounted in a standard wall tubular jacket having an internal diameter of <NUM> fitted with inlet and outlet connections. The jacket is connected to a source of water and the water temperature thermostatically controlled. In our experiments the water temperature was ambient. Fill the foam pipet with the test solution to the <NUM>-mL mark, using a slight suction for the purpose. Immediately place it in position at the top of the receiver making certain that the lower pipet tip is centered in the foam receiver and open the stopcock. When all of the solution has run out of the pipet, start a stop-watch, take an initial foam height reading at t=<NUM> minute followed by a final t=<NUM> minute reading. Take the reading by measuring the foam production at the top of the foam column at the highest average height to which the rim of the foam has reached. This height is proportional to the volume of air remaining in the foam.

The foam test was conducted per Method <NUM> except a <NUM>% solution was used and foam heights were measured at time T=<NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM> minutes.

Results from Method <NUM> are shown in Table <NUM>.

Results using Method <NUM> are shown in Table <NUM>.

Claim 1:
A composition comprising <NUM> to <NUM> weight % water, <NUM> to <NUM> weight% of a glycol selected from ethylene glycol, diethylene glycol, triethylene glycol, tetra ethylene glycol and propylene glycol, <NUM> to <NUM> weight % of a polyalkylene glycol, and <NUM> to <NUM>% of additives based on total weight of the composition wherein the polyalkylene glycol has a molecular weight of no more than <NUM>/mol, as measured by ASTM D4274, and is characterized in that it is an oxyethylene/oxypropylene block copolymer having a weight percent of oxyethylene of at least <NUM>% based on total weight of the copolymer, and further characterized in that the composition has an allyl content of less than <NUM>µeq allyl per gram of polyalkylene glycol (µeq /g), wherein allyl content is determined as set out in the description.