KR20230119171A - Biodegradable lubricant with tailored hydrolytic stability and improved thermal stability through alkoxylation of glycerol - Google Patents

Abstract

It significantly improves the thermal, oxidative and hydrolytic stability of the esters and allows for controlling the molar density of ester linkages in the lubricant, allowing insertion of alkoxy groups to maximize hydrolytic stability while maintaining biodegradability and further improving performance properties. Methods for stabilizing the beta hydrogen of glycerol-based esters by

Description

Biodegradable lubricant with tailored hydrolytic stability and improved thermal stability through alkoxylation of glycerol

The subject matter disclosed herein generally relates to a method for stabilizing the beta hydrogen adjacent to the ester linkage(s) of a glycerol derivative by insertion of an alkoxy group to significantly improve the hydrolytic and thermal stability of the ester linkage. This allows control of the molar density of ester linkages in the lubricant to maximize hydrolytic stability while maintaining biodegradability and further improving performance properties.

State-of-the-art [Rudnick, L. R. (ed.). (2020). Synthetics, Mineral Oils, and Bio-Based Lubricants (pp. 60, 131, 419). CRC Press] found that natural esters (triglyceride oils) are inferior base oils for use in industrial lubricants despite their excellent lubricity, high viscosity index, and high flash and ignition points while exhibiting high levels of bio content and biodegradability. considered to be In patent application WO 03/062355 A1, the disclosure states that, compared to glycerol, trimethylolpropane, pentaerythritol and neopentyl glycol "presence of a hydrogen atom in the beta position relative to the OH group (the presence of which prevents dehydration at elevated temperatures)". (emphasis added).

Various lubricants have been disclosed. For example, US Patent No. 3,337,595 discloses the preparation of fatty acid esters of propoxylated glycerol for use as antifoam aids. Preferred embodiments in the art are diesters of propoxylated glycerol and blends of said diesters with esters of fatty acid methyl esters and polyethylene glycols.

US Patent No. 3,530,070 discloses the use of propoxylated polyols as synthetic lubricants. The compositional space consists of a number of polyols (trimethylol propane, neopentyl glycol, pentaerythritol, dipentaerythritol, sorbitol and glycerol). This patent space covers materials with low bio content (<40%) or low biodegradation.

US Patent No. 4,031,118 relates to processes and compositions containing esters as detergents and dispersants in fuels and lubricants. The disclosed composition is a high MW (1000 to 10000 g/mol) polyether polyol (EO/PO copolymer) esterified with very long chain (≧C30) fatty acids. This patent space covers materials with low or negligible biobased carbon content and low biodegradability.

US Patent No. 5,916,854 discloses compositions and uses of interesterified and alkoxylated lubricating oils. The composition is the product of a process involving the interesterification of natural oils with glycerol or free fatty acids with simultaneous alkoxylation. The resulting product is a blend of many different compositions including monoesters, diesters and linear esters.

PCT WO1995002659 discloses a lubricating oil composition for use as a hydraulic fluid. Two processes are used to produce the claimed composition:

o Propoxylation of glycerol to an average of <3 PO units per glycerol (preferred embodiments are 1 PO units per glycerol) followed by esterification with FA from C6-C24.

o A one pot process, such as those listed under U.S. Patent No. 5,916,854, which produces a product by the process.

PCT WO2012134792 discloses a lubricant composition comprising a glycerol polymer propoxylated with an average of 6-15 PO units and then esterified with FAs from C8-C15. Preferred claims are alkoxylates of diglycerol and triglycerol (PO 8-12) and FA esters (C9-11).

PCT WO2014124698 relates to compositions and uses of pentaerythritol derived ester lubricants. A preferred composition as claimed and described consists of pentaerythritol having an average degree of propoxylation of 5 and subsequently esterified with C8/C10 fatty acids or oleic acid.

Patent application US2019/0367831 A1 of Tetramer Technologies discloses the use of esterified propoxylated polyols with long-chain fatty acids (≧C14) to prepare base oils with viscosities and pour points comparable to those of mineral base oils. are doing

The high temperature oxidative stability of lubricant molecules is highly dependent on the amount and composition of hydrogen on the beta carbon relative to the ester. In addition, natural esters with pour points suitable for industrial lubricants contain significant unsaturation and are prone to oxidative degradation, resulting in the formation of varnish and in some cases gelation of the oil, which reduces flow and potentially mechanical may cause a malfunction. Partially and fully saturated natural esters are oxidatively stable, but have poor low-temperature properties and tend to crystallize. Due to these limitations, natural esters are only used in applications such as total loss lubricants for environmentally sensitive applications.

Although synthetic neopentyl polyol esters are designed for high thermal oxidation and hydrolytic stability, it is well known to those skilled in the art that hydrolytic stability and biodegradability are closely related since the first step in biodegradation is hydrolysis of the ester. understood by Accordingly, materials designed for high levels of hydrolytic performance are not necessarily suitable as environmentally acceptable lubricants, and may further be poorly designed for biodegradation [Totten, G. E., Westbrook, S. R., Shah, R. J., (ed.). (2003). Fuels and Lubricants Handbook: Technology, Properties, Performance, and Testing (pp. 274). ASTM International].

Environmentally acceptable lubricants (EALs) are a new class of lubricants that may have various definitions depending on the country, industry and application. However, it is generally agreed that EALs should have good biodegradability, low bioaccumulation and low toxicity. Although not always a requirement, it is generally desirable for the EAL to have a high level of biobased carbon content in order to minimize the environmental impact of oil manufacture. As governmental and non-governmental organizations began to regulate and legislate the use of EALs, uniform standards began to emerge. The European EcoLabel uses a definition that requires the lubricant to be non-toxic, non-bioaccumulating and biodegradable (>60% biodegradable according to OECD 301B). If a lubricant is labeled as "bio-based" or "bio-lubricant", according to Commission Decision (EU) 2018/1702 it must have a bio-based carbon content greater than 25%.

What is needed in the art is the modification and composition(s) of glycerol ester lubricants wherein the molecules have optimized hydrolytic stability to maximize performance while still passing high levels of bio content and biodegradation tests. In addition, these modifications and composition(s) of glycerol esters should improve oxidation and thermal stability while improving cold weather performance.

Citation or identification of any document in this application is not an admission that such document is available as prior art to the present disclosure.

In certain example embodiments, synthetic ester lubricating base oils are provided. The base oil may include an ester of alkoxylated glycerol having an average degree of alkoxylation of ≧3, and at least one fatty acid having ≧8 carbon atoms. The synthetic lubricating base oil exhibits increased oxidation, thermal and hydrolytic stability, reduced melting enthalpy and reduced undercooling compared to glycerol esters having the same fatty acid composition, and for each fraction of the synthetic lubricating base oil has a single crystal melting point or It has an amorphous phase. In addition, the thermal oxidation stability of the synthetic ester lube base oil is greater than 25%, more preferably 40% as determined by the Rotating Pressure Vessel Oxidation Test (RPVOT) life compared to glycerol esters of the same fatty acid composition. greater than, more preferably greater than 60%. In addition, the hydrolytic stability of the base oil can be improved as measured by a reduction in the total acid value number by greater than 50%, more preferably greater than 60%, and more preferably greater than 70%. In addition, the melting enthalpy can be reduced by more than 50%, more preferably by more than 60%, more preferably by more than 70% and even more preferably by more than 80% for a glycerol ester having the same fatty acid composition. Also, the melting enthalpy can be reduced so that the lubricant does not exhibit a detectable cloud point and remains transparent. Also, undercooling can be reduced by more than 30%, preferably more than 50%, more preferably more than 70%, even more preferably more than 75%. Alkoxylates can also be derived from ethylene oxide (EO), propylene oxide (PO), butylene oxide (BO) or combinations thereof. Also, the alkoxylated glycerol may preferably have in the range of 3 to 20 propoxy groups per molecule, more preferably in the range of 5 to 12, even more preferably in the range of 8 to 11, and even more preferably in the range of 8 to 11. It is preferably a degree of propoxylation of 10. Also, the at least one fatty acid may be a dicarboxylic acid. In addition, dicarboxylic acids include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, octane Decanedioic acid or a combination thereof. Additionally, at least one fatty acid may be a functionalized acid. Functionalized acids may also include 12-hydroxystearic acid. Functionalization may also include epoxidation, maleination, metathesis, amidation, halogenation, hydration, hydrogenation, estolide formation, hydroformylation, dimerization or vulcanization of synthetic esters. can Additionally, at least one fatty acid may be branched. Branched acids may also include 2-ethylhexanoic acid or isostearic acid. In addition, the lubricating base oil may be more than 40% biodegradable in the 10-day window of the OECD 301B test. Additionally, the lubricating base oil may be at least 25% biobased carbon. In addition, the present disclosure provides antioxidants, antiwear agents, corrosion inhibitors, anti-sludge agents, antifoaming agents, demulsifiers, viscosity index improvers, detergents/dispersants, pour-point depressants, alkalinity improvers, friction modifiers , a seal swelling agent, a metal deactivator/complexing agent and/or an extreme pressure agent. Additionally, the thermal oxidative stability as determined by the RPOVT lifetime may be greater than 600 minutes, more preferably greater than 800 minutes, and even more preferably greater than 1000 minutes.

In a further embodiment, the present disclosure provides synthetic ester lube base oils as hydrolytically stable and biodegradable lubricants. In addition, alkoxylated glycerol esters have hydrolytic stability and biodegradability by tailoring ester bond stability and ester density through the use of alkoxylation, wherein the degradation products of alkoxylated glycerol esters are non-toxic. The ISO viscosity grade of the lubricant may be 32 to 150, more preferably 46 to 100, even more preferably 46 to 68.

The present disclosure also provides methods for stabilizing the beta hydrogens of glycerol esters and diluting the molar density of ester linkages in the ester base oil to form alkoxylated glycerol esters that are thermally, oxidatively and hydrolytically stable, wherein the The hydroxyl groups are alkoxylated with ethylene oxide, propylene oxide, butylene oxide or combinations thereof.

These and other aspects, objects, features and advantages of the exemplary embodiments will become apparent to those skilled in the art upon consideration of the following detailed description of the exemplary embodiments.

An understanding of the features and advantages of the present disclosure will be obtained by reference to the following detailed description and accompanying drawings, which set forth exemplary implementations in which the principles of the present disclosure may be employed.
Figure 1 shows schematics of glycerol esters (left) and alkoxylated glycerol esters (right), highlighting the α and β hydrogens of each species, and primary and secondary alcohols.
Figure 2 shows the compositions of Table 1: Disclosure Examples.
Figure 3 shows Table 2: 1H NMR shifts for methylene and methine protons of natural and synthetic ester backbones.
Figure 4 shows Table 3: RPVOT data for pure and formulated base oils.
5 shows Table 4: Hydrolysis Stability (ASTM D2619) data for saturated ester base oils.
6 shows Table 5: Thermodynamic data for C12 esters analyzed by differential scanning calorimetry.
Figure 7 shows Table 6: Supercooling and melting enthalpies of pseudoglycerol, TMP and propoxylated glycerol esters.
Figure 8 shows Table 7: Low temperature behavior of various esters.
9 shows Table 8: PG10-Whole Cut Fatty Acid Esters.
Figure 10 shows Table 9: Biodegradation according to OECD-301B.
Figure 11 shows Table 10: Percent biobased carbon (ASTM method D6866-20).
Figure 12 shows Table 11: PG10 branched, functional and diacid esters.
Figure 13 shows Table 12: Formulated Oil Performance Comparison.
Figure 14 shows Table 13: Examples of ethoxylated glycerol esters.
Numerical values herein are for illustrative purposes only and are not necessarily drawn to scale.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Before the present disclosure is described in more detail, it should be understood that the present disclosure is not limited to the particular implementations described and may of course vary accordingly. Also, it should be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. Although any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the present disclosure, the preferred methods and materials are now described.

All publications and patents cited herein are incorporated to disclose and describe methods and/or materials related to the cited publications. All such publications and patents are specifically and individually incorporated herein by reference as if each individual publication or patent were indicated to be incorporated by reference. Such incorporation by reference is expressly limited to the methods and/or materials described in the cited publications and patents, and does not extend to any dictionary definition of the cited publications and patents. Any dictionary definitions in the cited publications and patents not expressly reiterated also in this application should not be so treated, and should not be construed as defining any term appearing in the appended claims. . Citation of any publication is for its disclosure prior to the filing date and is not to be construed as an admission that this disclosure is not entitled to antedate such publication by reason of prior disclosure. Additionally, the publication date of a given publication may differ from the actual publication date, which may need to be independently verified.

As will be apparent to those of ordinary skill in the art upon reading this disclosure, each of the individual embodiments described and illustrated herein may benefit from the features of any of several other embodiments without departing from the scope or spirit of the present disclosure. It has distinct components and characteristics that can be properly separated or combined. Any recited method may be performed in the recited order of events or any other order logically possible.

Where ranges are expressed, additional embodiments include from one particular value and/or to another particular value. The recitation of numerical ranges by endpoints includes all numbers and fractions subsumed within each range as well as the recited endpoints. Where a range of values is provided, each intervening value between the upper and lower limits of that range, and any other stated or intervening value in that stated range (unless the context clearly dictates otherwise, the tenth of the unit of the lower limit up to) are understood to be included within this disclosure. The upper and lower limits of these smaller ranges may independently be included in the smaller ranges and are also encompassed within the disclosure, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included in the disclosure. For example, where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included in the disclosure, e.g., the phrase "x to y" Includes ranges up to and including 'y' as well as ranges greater than 'x' and less than y'. The range can also be expressed as an upper limit, e.g., 'up to about x, y, z', as well as specific ranges of 'about x', 'about y' and 'about z', as well as 'less than x', 'y' less than' and 'less than z'. Likewise, the phrase 'more than about x, y, z' includes the specific ranges of 'about x', 'about y' and 'about z', as well as the ranges of 'greater than x', 'greater than y' and 'greater than z'. should be interpreted as Also, the phrase about "'x' to 'y'" includes "about 'x' to about 'y'" when 'x' and 'y' are numerical values.

It should be noted that ratios, concentrations, amounts and other numerical data may be expressed herein in a range format. It will further be understood that each endpoint of a range is significant relative to and independently of the other endpoints. It is also understood that there are a number of values disclosed herein, and that each value is also disclosed herein as “about” the corresponding value in addition to the value itself. For example, if the value "10" is disclosed, "about 10" is also disclosed. Ranges may be expressed herein as “about” one particular value and/or “about” another particular value. Similarly, when a value is expressed as an approximation by use of the antecedent "about", it will be understood that the particular value forms an additional aspect. For example, if the value “about 10” is disclosed, “10” is also disclosed.

This range format is used for convenience and brevity, and therefore includes not only the expressly recited numerical values as limits of that range, but also any individual numerical value or subrange subranged within that range as if it were each numerical value and It should be understood that subranges should be construed in a flexible manner as inclusive as if explicitly recited. For purposes of illustration, a numerical range of “about 0.1% to about 5%” includes not only the explicitly recited values of about 0.1% to about 5%, but also individual values within the indicated ranges (e.g., about 1%, about 2%, about 3% and about 4%) and subranges (eg, about 0.5% to about 1.1%; about 0.5% to about 2.4%; about 0.5% to about 3.2%, and about 0.5% to about 4.4%, and other possible subranges).

As used herein, the singular forms “a”, “above” and “the” include both singular and plural referents unless the context clearly dictates otherwise.

As used herein, "about", "approximately", "substantially", etc., when used in reference to a measurable variable such as a parameter, amount, temporal period, etc. of specified values, including those within a given confidence interval (e.g., 90%, 95%, or greater confidence interval from the mean value), and/or may be determined by an accepted standard of and variations from the values specified above, such as variations of no more than +/-10%, no more than +/-5%, no more than +/-1% and no more than +/-0.1% of and from the specified values (such variations as far as is suitable for practice in this disclosed disclosure). As used herein, the terms "about," "approximately," "approximately," and "substantially" mean that the amount or value does not represent the exact value, or result or effect equivalent to that recited in the claims or taught herein. It can mean that it can be a value provided. That is, amounts, sizes, formulations, parameters, and other quantities and characteristics are not and need not be exact, but are subject to tolerances, conversion factors, rounding, measurement errors, etc., and those common in the art so that equivalent results or effects are obtained. It is understood that these values may be approximations and/or greater or lesser if desired, reflecting other factors known to the skilled artisan. In some cases, values giving equivalent results or effects cannot be reasonably determined. Generally, an amount, size, formulation, parameter, or other amount or characteristic is “about,” “approximately,” or “approximately,” whether or not explicitly stated as such. When "about", "approximately" or "approximately" is used before a quantitative value, it is understood that the parameter also includes the specific quantitative value itself, unless specifically stated otherwise.

The term “optional” or “optionally” means that a subsequent described event, circumstance or substituent may or may not occur, and the description is implied when that event or circumstance occurs and when it does not. means to include

As used herein, the term “molecular weight” can generally refer to the molar mass or average mass of a material. A mole is a defined number of molecules (Avogadro constant). For polymers or oligomers, molecular weight can refer to the relative average chain length or relative chain mass of the bulk polymer. Indeed, the molecular weight of polymers and oligomers can be estimated or characterized in a variety of ways including gel permeation chromatography (GPC) or capillary viscometers. GPC molecular weight is reported as weight average molecular weight (M _w ), not number average molecular weight (M _n ). Capillary viscometers provide an estimate of molecular weight as intrinsic viscosity determined from dilute polymer solutions using a specific set of concentration, temperature, and solvent conditions.

As used herein, the terms “weight percent,” “weight percent,” and “wt. %,” which may be used interchangeably, refer to the weight percentage of a given component based on the total weight of the composition that is the component, unless otherwise specified. indicate That is, unless otherwise specified, all weight percent values are based on the total weight of the composition. It should be understood that the sum of weight percent values for all components of a disclosed composition or formulation equals 100. Alternatively, it is to be understood that the sum of the weight percent values of specified components in a disclosed composition or formulation equals 100 when weight percent values are based on the total weight of a subset of components in a composition.

As used herein, the term ester refers to a type of chemical bond or alternatively to a type of molecule composed of ester bonds. Fully esterified ester variants of a molecule when referring to a class of molecule, as in "alkoxylated glycerol ester", "propoxylated glycerol ester", "glycerol ester", "TMP ester" and "synthetic ester" It should be understood that is described. In oil chemistry, it is not uncommon to have monoacylglycerides or diacylglycerides, which are esters but not equivalent to triacylglycerides. When glycerol esters or alkoxy esters are described, fully esterified molecules are described. A fully esterified ester is one where a hydroxyl value of less than 15 mg KOH/g, or more preferably less than 10 mg KOH/g, or most preferably less than 5 mg KOH/g is achieved. I understand.

When referring to an alkoxylated material, EO, PO and BO may be used to describe the alkylene oxide reactants ethylene oxide, propylene oxide and butylene oxide, respectively, or EO, PO and BO respectively It should be understood that it can be used to describe the polyether composition of alkoxylated glycerol, ethoxy, propoxy and butoxy. Also, propoxylation and oxypropylation are used synonymously, as are propoxylated and oxypropoxylated. Likewise, ethoxylation and oxyethylation are used synonymously, as are ethoxylated and oxyethylated.

The term "degree of alkoxylation" herein is to be understood as meaning the average number of alkylene oxide molecules (EO, PO and/or BO) attached to a given polyol molecule. When describing the degree of alkoxylation, the sum of x+y+z as shown in FIG. 1 in B is the degree of alkoxylation, where x, y and z are integers. Also, the degree of alkoxylation can be the average degree of alkoxylation for all molecules, so that the degree of alkoxylation can be an integer or fractional number. In US Pat. No. 6,495,188 B2, for example, it was found that a stoichiometric ratio of alkoxylation of 3 PO per glycerol results in approximately 63% of the glycerol hydroxyl groups being reacted. A degree of alkoxylation of 4 resulted in 82% of the free glycerol hydroxyl groups being alkoxylated, and a degree of alkoxylation of 5 resulted in complete alkoxylation.

As used herein, “intercalation” should be understood to mean the introduction of an alkoxy group into a molecular structure, but not in the chemical sense of the reaction mechanism.

Various implementations are described below. It should be noted that specific embodiments are not intended as exhaustive descriptions or as limitations on the broader aspects discussed herein. An aspect described in the context of a particular implementation is not necessarily limited to that implementation and may be practiced with any other implementation(s). Throughout this specification, references to "one embodiment," "an embodiment," or "an exemplary embodiment" are references to a particular feature, structure, or characteristic described in connection with that embodiment, to at least one embodiment of the present disclosure. means included. Thus, the appearances of the phrases “in one embodiment,” “in an embodiment,” or “an exemplary embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment, but may. In addition, particular features, structures, or characteristics may be combined in one or more embodiments in any suitable manner, as will be apparent to those skilled in the art from this disclosure. Further, while some embodiments described herein include some but not other features included in other embodiments, combinations of features of different embodiments are intended to be within the scope of this disclosure. For example, in the appended claims, any of the claimed embodiments may be used in any combination.

All publications, published patent documents and patent applications cited herein are herein incorporated by reference to the same extent as if each individual publication, published patent document or patent application was specifically and individually indicated as being incorporated by reference.

The main difference between the present invention and the prior art is the use of alkoxylated glycerol as polyol for synthetic esters. Fatty acids of ≧C8 and alkoxylated glycerols with a degree of alkoxylation of ≧3 are used to control the biobased content and biodegradation of the resulting synthetic esters. It has also been found that customizing the fatty acid and alkoxylated glycerol composition allows tailoring the hydrolysis and thermal oxidation stability of the alkoxylated glycerol esters.

The assumption of the instability of the hydrogen at the beta position of the primary ester on glycerol has led to the failure of previous efforts to specify alkoxylated glycerol ester lubricants, and has instead focused on the alkoxylation of neopentyl polyols. In U.S. Pat. No. 3,530,070, the inventors describe the synthesis of four propoxylated polyol esters, but only one composition, which is a propoxylated (14 PO) TMP esterified with a fatty acid having an average length of C8. materialize In this patent, measurements of the lubricating performance of glycerol-based materials are not made or disclosed beyond measurements of viscosity and pour point. Consequently, the public has not yet had the opportunity to enjoy the benefits of alkoxylated glycerol ester base oils. The present disclosure observed an unexpectedly high stability of propoxylated glycerol ester molecules and specified lubricants through detailed studies of compositions and formulated lubricants.

The present disclosure describes methods and composition(s) for modification of glycerol esters wherein glycerol is used to improve oxidation, thermal and hydrolytic stability compared to unmodified glycerides while having pour points and viscosity indices generally required for lubricating oils. is alkoxylated and esterified. In addition, the inventors have found that the performance of formulated propoxylated glycerol ester base oils exhibit superior lubricating properties than comparable commercial formulated base oils, especially when compared to environmentally acceptable base oils ( 13, see Table 12). Base oils are used to make products including hydraulic fluids, turbine fluids, compressor fluids, lubricating greases, motor oils and metalworking fluids. Synthetic esters, including alkoxylated glycerol esters, the lubricating oil composition may include other conventional oil additives to the formulated lubricant.

The inventors have discovered that substantially complete alkoxylation of the glycerol hydroxyl groups allows for the preparation of biodegradable glycerol derived ester base oils with increased stability of the esters and reduced molar density of ester linkages in the base oil. In triglycerides, the two primary esters have a methine proton at the beta position relative to the ester linkage at A (see Figure 1). By reacting the alkoxy linkage (ether) on glycerol prior to fatty acid esterification in B (FIG. 1), the proton in the beta position to the ester is now the more stable methylene proton. When the degree of alkoxylation is ≥3 (on glycerol), the alkoxy groups will react with the primary hydroxyl groups of glycerol, and the resulting alkoxylated glycerol esters will be glycerol due to significant coverage of the primary hydroxyl groups of glycerol. It is expected to have improved stability compared to esters of In addition, esters with a degree of alkoxylation of ≧5 are expected to have improved stability over esters with a degree of alkoxylation of ≧3. The improved stability of the esters when the degree of alkoxylation is ≧5 is due to full coverage of the glycerol hydroxyl groups. If all glycerol hydroxyls are alkoxylated, subsequent ester linkages will only have β methylene protons, whereas partial reaction of the glycerol hydroxyls allows for the generation of β methine protons. In addition, all β methylene protons will be stabilized by adjacent ether groups. Ether bonds can only be hydrolyzed by strong haloacids. Ether molecules cannot form hydrogen bonds with each other and are stable compounds, whereas esters can form hydrogen bonds, making them relatively less stable. Also, ether bonds are electron donating. Accordingly, the glycerol methine protons of alkoxylated glycerol esters bind more strongly to glycerol. Ether linkages will also stabilize the beta-methylene protons on alkoxylated glycerol esters.

In addition to stabilizing the methine protons of glycerol (on the secondary carbon), the polyether spacer also physically separates and isolates the ester bond from glycerol. This limits the formation of a transition state 6-membered ring with the methine group of glycerol, which is understood to allow thermal decomposition of triglyceride oils (glycerol esters). [Rudnick, L R (ed.). (2020). Synthetics, Mineral Oils, and Bio-Based Lubricants (pp. 60). CRC Press] The instability of beta hydrogens in glycerol esters due to adjacent ester groups was addressed by inserting a stabilizing polyether spacer. The hydrogen atom at the new beta position is located on an ester-adjacent alkoxy group surrounded by a stabilizing ether group.

When the terminal alkoxy group of the alkoxylated glycerol ester is a propoxy or butoxy group, the alkoxylated glycerol ester has both the hydroxyl groups of the propoxy and butoxy groups compared to the two primary and one secondary hydroxyl groups on glycerol. Being a secondary alcohol, it is considerably more stable than glycerol esters. It is well known that secondary hydroxyl groups result in more stable ester bonds compared to esters of primary hydroxyl groups. This may be due to modifications induced on the carbon backbone that help to inhibit the formation of the transition state 6-membered ring that allows thermal decomposition of the ester. Esterification of alkoxylated glycerol terminated with propoxy or butoxy groups results in more sterically hindered and electronically stable secondary ester linkages compared to glycerol esters. It is noted that ethoxylated glycerol esters will have primary esters but still exhibit greater stability than similar glycerol esters.

Further stabilizing the alkoxylated glycerol ester oils of the present disclosure, the beta hydrogens of the alkoxylated glycerol esters are methylene hydrogens. It is known to those skilled in the art that hydrogen bond stability decreases in the order methyl>methylene>methine. The classic “beta hydrogen argument” for glycerol backbone chemistry in base oils is the result of primary esters extracting the methine hydrogen of the beta carbon. In one embodiment, the propoxylated glycerol ester has a decomposition mechanism based on a secondary ester that extracts the methylene hydrogen of the beta carbon now located at the terminal propoxy unit. The resulting propoxylated glycerol ester oil(s) of the present disclosure include a stabilizing polyether spacer (polyalkoxy) between the fatty acid(s) of the glycerol and triglyceride oil.

Another method for controlling the thermal, oxidative and hydrolytic stability of alkoxylated glycerol esters is to increase the molecular weight of the alkoxy groups, thereby reducing the overall molar density of ester bonds in the alkoxylated glycerol esters compared to the glycerol esters. confirmed from Because ester linkages tend to be weak linkages in the degradation of synthetic esters, thermal, oxidative and hydrolytic stability are improved when the number of ester linkages is reduced.

Oxidation stability for commercial and industrial materials is often performed according to the Rotary Pressure Vessel Oxidation Test (RPVOT) as specified in ASTM D2272. RPVOT results can be used to compare the relative stability of base oils in the presence of water, oxygen, catalyst and heat. RPVOT was performed to evaluate the thermal oxidation stability of glycerol ester and propoxylated glycerol ester base oils. In this test, longer life equals more stable base oils and oil formulations. Figure 4, Table 3 compares the RPVOT data of two natural glycerol esters, one trimethylolpropane (TMP) ester and two propoxylated glycerol esters without any additives to enhance performance. This data confirms that greater than 60% increase can be observed in the overall stability of propoxylated glycerol esters (both saturated and unsaturated) when compared to glycerol esters. TMP esters perform relatively poorly in this test despite the lack of beta protons. In formulated lubricant systems, propoxylated glycerol esters were found to have RPVOT lives to the same extent as commercial petroleum based turbine oils (see FIG. 13, Table 12). When compared to formulated natural glycerol ester lubricants, propoxylated glycerol ester turbine lubricants have been shown to have a 375% to 1000% increase in life. Also in Table 12, the propoxylated glycerol ester turbine lubricant is shown to have superior oxidation onset temperature (OOT) as measured by ASTM E2009-08 compared to Chevron GST. TMP trioleate has been shown in the literature to have an OOT of 156° C. and up to 206° C. after formulation [Wu, Y., et al; Thermochimica Acta , 569, 2013, pp. 569; 112-118]. While this high level of thermal and oxidative performance for alkoxylated glycerol is surprising, it should be noted that biodegradable base oils can be too stable, specifically with respect to hydrolytic stability.

Control of the molar density of ester linkages through the degree of alkoxylation of the alkoxylated glycerol esters allows tailoring of the hydrolytic stability, an important tool in the development of optimized biodegradable base oils. It is well understood that the first step in biodegradation in natural or synthetic esters is hydrolysis of the ester linkages. Accordingly, oils with very high hydrolytic stability can be expected to fail the OECD 301B biodegradability test. A well-designed environmentally acceptable oil will optimize hydrolytic performance by tailoring the stability of ester bonds and controlling ester molar density to achieve maximum hydrolytic stability of the base oil while still passing the OECD 301B biodegradability test. . For current OECD 301B requirements, a “readily biodegradable” material must exhibit at least 60% degradation within a 10-day period starting after 10% degradation is observed. The most optimized hydrolytically stable biodegradable base oil will exhibit greater than 60% degradation at 10 days of this period. Figure 10, Table 9 shows examples with optimized ester densities. The base oils of the present invention are expected to meet or exceed the thresholds of other conventional biodegradation tests.

Passing OECD 301B, Figure 5, Table 4 shows the excellent performance of propoxylated glycerol esters with respect to hydrolytic stability. It is worth noting that the performance of alkoxylated glycerol esters is superior to that of unsaturated polyol esters in hydrolytic stability. Unsaturated polyol esters are known to have similar hydrolysis performance to unsaturated glycerol esters [ Fuels and Lubricants Handbook , ^2nd ed., p. 560]. Although it is not fully understood why propoxylated glycerol esters have such significant improvements in hydrolytic stability, it is clear that there are novel effects from performance. Looking at the weight change of Cu panels, saturated propoxylated glycerol esters (Examples 91 and 103) were 7 to 10 times more than saturated glycerol esters (Example 92) and saturated TMP esters (Example 90). low can be seen. In addition, the total number of AVs of Examples 103 and 91 were 4 to 7 times lower than those of glycerol esters and TMP esters. The explanation can be found in the alkoxy group itself. US patent application 20170240833 teaches that polyalkylene glycols are known to improve hydrolytic stability when blended with other base oils, and blending triblock polyalkylene glycols at about 10% with vegetable oils or synthetic esters. See US Patent Application 20140107004A1 which teaches that hydrolytic stability can be greatly improved. It is proposed that the increase in hydrolytic stability may be related to latent water, i.e., water bound by hydrogen bonds to ether bonds that is not free to participate in hydrolysis until saturation of the oil is achieved. do. If this proposed mechanism is correct, it will be just one additional contributing factor to the overall thermal oxidation and hydrolytic stability.

melt thermodynamics

It is known in the art that alkoxylation has the potential to reduce the pour point of an ester. However, the present disclosure observed a surprising decrease in melting enthalpy and a significant decrease in degree of supercooling. The degree of supercooling of a base oil refers to the increase in temperature required to completely melt the oil after crystallization begins. The degree of supercooling for purposes of this disclosure is the temperature between the temperature at which a material completely melts upon heating and the temperature at which it begins to crystallize upon cooling, as determined by differential scanning calorimetry (DSC) at a heating and cooling rate of 5° C./min. The difference is described as [T _melt - T _onset = supercooling]. "Supercooling" and "degree of supercooling" may be used synonymously.

Changes in the intrinsic thermodynamics of esters through alkoxylation allow the preparation of base oils that are more resistant to crystallization and gelation, and detrimental effects have been noted when the oil is handled around and below its pour point. The higher the melting enthalpy, the more stable the solid form of a given material. A reduced melting enthalpy for a material indicates an increase in the amount of a less stable crystalline structure or amorphous phase. In either case, the result is that less heat is required to remelt the solidified material. In addition, the decrease in melting enthalpy for some alkoxylated glycerol esters was shown to be reduced by DSC to the point where no crystallization was observed and there was no discernible cloud point during the test.

The thermodynamic properties of a given base oil can be thoroughly investigated using DSC in addition to traditional qualification tests (e.g., cloud point and pour point). For the materials investigated in this patent, pour point (modified ASTM D97), cloud point (modified ASTM D2500) and onset of crystallization (DSC) were observed. When operating conditions fall below the pour point of a given lubricant, the oil gels or freezes. If two oils have similar pour points, the oil with a lower enthalpy of melting and a reduced degree of supercooling will be in a fluid state at a lower temperature and in a shorter time compared to an oil with a higher enthalpy and a greater degree of supercooling. will be restored with Esters of alkoxylated glycerol have been found to exhibit reduced enthalpy and supercooling when compared to natural esters and neopentyl polyol esters, resulting in faster melting behavior. Representative comparisons of natural esters, neopentyl polyol esters, and alkoxylated esters are described in the Examples of this disclosure.

The ASTM required equipment for ASTM D97 and ASTM D2500 was modified as follows: A cooling water bath was prepared in a cylindrical stainless steel thermos (dimensions 70 mm x 110 mm) and filled with isopropyl alcohol. The bath temperature was reached as described by ASTM and maintained through manual addition of dry ice. To serve as a cooling jacket, a test tube (25 x 150 mm, OD x length) with a 25x25 mm piece of fabric cushion placed at the bottom was set to cool in an IPA/CO ₂ (s) water bath. . An 8 ml specimen was filled into a sample tube (15 x 150 mm; OD x length). A low-temperature thermometer (to -100 °C) is placed into the sample tube through a rubber stopper (one hole stopper that fits snugly on the thermometer), allowing the temperature of the sample liquid to pass without the thermometer bulb touching the test tube. It was placed under the meniscus. The sample tube was then placed into a cooling jacket, upright, and held nearly vertical in place. The test sample was monitored and the pour point/cloud point was recorded according to ASTM guidelines.

A single melting event is also noted for esters of alkoxylated glycerol using DSC. Natural esters and esters of neopentyl polyol tend to exhibit an exothermic phenomenon near their melting transition, which indicates the formation of a more stable and higher melting crystalline solid.

Oils exhibiting multiple melt phase transitions may also suffer from the growth of high stability crystal phases when the oil is thermally cycled close to the onset of crystallization. This well-known phenomenon occurs due to the increased thermal stability of the particles in the high melting crystalline phase that remain after partial melting (the particles serve as seed crystals).

Oils with lower subcooling require less increase in temperature to melt the oil and clear the oil "memory" after crystallization. Shelby and Miller teach the concept of oil "memory" as a result of which the gels or crystals do not completely dissociate even above the melting point so that gelation or crystal growth occurs much faster and at higher temperatures on the second cooling cycle. If two oils have the same crystallization onset temperature, the oil with the lower supercooling will completely melt at the lower temperature and erase the oil "memory". Propoxylated glycerol esters have a supercooling value of the order of 10°C, whereas triglycerides exhibit a degree of supercooling of the order of 20 to 40°C. The effect of this is that the glycerol esters and polyol esters must be heated substantially above the onset of crystallization to melt the oil before use. Selby, T. and Miller, G., "Thermal History of the Engine Oil and Its Effects on Low-Temperature Pumpability and Gelation Formation," SAE Technical Paper 2008-01-2481, 2008, https://doi.org /10.4271/2008-01-2481]. Figure 6, Table 5 shows this effect through four examples, all based on the trilaurate ester. At 5° C. above the crystallization onset temperature, 100% of Example 92 (glycerol ester) is a solid; 31% of Example 93 (PG3 ester) is solid; 18% of Example 94 (PG10 ester) is solid; 81% of Example 90 (TMP ester) is a solid. At 10° C. above the crystallization onset temperature, DSC measurements show that the glycerol esters are not melted at all, the TMP esters are 46% solids, while the propoxylated glycerol esters have very little solids (less than 4%). From this data it is clear that propoxylated glycerol esters have unexpectedly low temperature recovery from excursions below the pour point or cloud point.

Blown Oil

Blown oil is a drying oil that has been modified through an oxidation process at elevated temperatures and is manufactured to specific viscosity specifications ranging from 1 poise @ 25°C up to 1600 poise @ 25°C depending on the type of oil. The oxidation process results in chemically modified products containing polymerized triglyceride esters with additional bound oxygen. Peroxide, hydroperoxide and hydroxyl groups are also present. The oxidation process also modifies properties such as specific gravity, solubility and reactivity.

Blown stripped oil blends can be used for end applications requiring or utilizing oils with high flash points and increased viscosities. For example, blown stripped oil blends are particularly suitable for dust removal fluids. Blowing oils also include a number of products including cutting fluids, rolling and metal working fluids, drilling mud, two stroke engine oil, grease, wire drawing and chainsaw lubricants. It has uses in lubricant applications of Blown oil decomposes more slowly than petroleum-based mineral oils, which have lower flash points.

In one aspect, the present disclosure provides a synthetic lubricating base oil. The base oils are esters of alkoxylated glycerol having an average degree of alkoxylation of ≥3, such as 4, 5, 6, 7, 8, 9, 10, and ≥8, such as 9, 10, 11, 12, 13, 14, 15, and at least one fatty acid having 16, 17, 18 or more carbon atoms, wherein the melting enthalpy is significantly reduced and supercooling is reduced. In many cases, the melting enthalpy for propoxylated glycerol esters with an average degree of alkoxylation of ≧3 was reduced by >50% for triglycerides with similar fatty acid compositions (see Table 5). When the degree of propoxylation is about 10, the melting enthalpy is reduced by 70-80% relative to similar triglycerides (see Table 6). Samples with a lower enthalpy of less than 15 J/g were visually observed to have reduced crystallization and greater clarity upon solidification compared to samples with an enthalpy of greater than 15 J/g. This results in higher levels of low melting fatty acids such as oleic acid, linoleic acid, capric acid and caprylic acid, and propoxylation levels of greater than 3, more preferably greater than 5, even more preferably greater than 10. As observed for propoxylated glycerol esters having a fatty acid composition with In these samples, no cloud point was recorded and the transparency remained well below -50 °C. By reducing the level of propoxylation, for example from 10 to 5, or by reducing the relative concentration of low-melting fatty acids, including propoxylated glycerol esters, transition of clear samples to translucent samples was observed. This can be observed in Figure 8, Table 7. In addition to fully propoxylated examples, some alkoxylated samples that were propoxylated prior to esterification and capped with ethoxy groups were also observed to be translucent. It should be noted that when the melting enthalpy falls below about 15 J/g, the integration point in the DSC thermogram becomes difficult to define, and an observable crystallization peak may be difficult to measure or even visually observe. do.

In many cases, undercooling for propoxylated glycerol esters with an average degree of alkoxylation > 3 was reduced by more than 15° C. for triglycerides with similar fatty acid compositions (see FIG. 7, Table 6). When the degree of propoxylation is about 10, the degree of undercooling can be reduced by more than 20° C. for triglycerides with similar fatty acid composition. The fatty acid composition of propoxylated glycerol esters, which already exhibit a low degree of supercooling as triglycerides such as coconut oil, exhibit a lower decrease in supercooling. The reduction in supercooling due to the addition of a propylene glycol spacer between glycerol and fatty acids is greater than 30% reduction in bulk phase supercooling, more preferably greater than 50% reduction, more preferably greater than 70% reduction, even more preferably 75 % reduction can be observed. Indeed, certain reductions of 76.1%, 38.3%, 77.7%, 67.2%, 81.3%, 74.8%, 72.7% are considered within the scope of this disclosure.

Generally, bulk crystallization of a material is the intent of the above teachings, and the onset temperature of crystallization in the bulk phase is used to determine the degree of subcooling. It is understood that the addition of another component with a higher melting point may alter the measured subcooling. This small phase is not used as an initiator of crystallization; Care must be taken to distinguish this small crystallization from the bulk phase crystallization.

Also, the alkoxylate can be ethylene oxide, propylene oxide, butylene oxide or combinations thereof.

It is well known that the polarity of alkoxylated glycerol is highly dependent on the ratio of EO, PO and BO used in the polyether segment. Alkoxylated glycerols with higher EO have increased polarity resulting in higher levels of solubility in water, whereas increasing the amount of PO results in less polar alkoxylated glycerol esters with greater oil solubility. It is also known that exceeding a certain number of EO groups in a block can create problems with crystallization of the EO block. This ratio of EO-PO allows considerable control in the development of surfactants. Polyalkylene glycol (PAG) lubricants exploit these properties and were originally used in water-based lubricants. More recently, commercially available PO/BO and BO lubricants have been introduced. In US Patent 10,160,928 B2, BO is disclosed to reduce problems associated with demulsification of UCON OSP lubricants.

Alkoxy groups with increased EO/PO ratios have greater water solubility. It has also been found that deemulsification of propoxylated glycerol esters can be difficult depending on the degree of propoxylation and the fatty acid composition. Accordingly, it will be expected and asserted that lubricants that are PO/BO glycerol esters or even BO glycerol esters are expected to have improved performance, especially with respect to oil solubility and demulsification.

It is also understood by those skilled in the art that there is a range of additives with varying degrees of effectiveness for improved demulsification, and this dependence includes base oil and whole oil formulations. Included among these additives will be those already known to be effective as demulsifiers in base oils that are triglyceride based, synthetic ester based, polyalkylene glycol based or other Group I, II, III or IV based oils. U.S. Patent 6,495,188 teaches the presence of ethoxy groups to modulate the emulsion stability of propoxylated glycerol esters, and likewise replacing some propoxy groups with other alkoxy groups having greater hydrophobicity will increase the overall hydrophobicity.

We prepared ethoxylated glycerol esters with molecular weights similar to propoxylated glycerol esters within about 6%. Ethoxylated glycerol exhibited very similar viscosities with a higher viscosity index compared to propoxylated glycerol esters with the same fatty acid composition (see Figure 14, Table 13). In addition, the pour point of the ethoxylated glycerol esters increased by more than 20 °C. This can be explained by the greater polarity of ethoxy groups compared to propoxy groups. The solubility in water was found to be significantly higher for ethoxylated glycerol esters than for propoxylated glycerol esters. It was observed that the EO sample had a water solubility of 6.04%, while the PO sample had a solubility of 0.58% as determined by Karl Fischer titration at room temperature. Accordingly, it would be expected that base oils in which the alkoxylates are alkoxylated glycerol esters that are blends of PO/BO or even BO alone would be expected to have improved performance, particularly with regard to oil solubility and demulsification. Thus, in one embodiment, an optimal base oil design may favor the use of ethoxylation of glycerol; It is understood by those skilled in the art that in another embodiment for the base oil it may be desirable to use butoxylation of glycerol.

The alkoxylated polyol preferably has 3 to 20 propoxy groups per molecule, more preferably a degree of propoxylation in the range of 5 to 12, more preferably in the range of 8 to 11, more preferably 10. It may be propoxylated glycerol.

A variety of sources for fatty acids are possible. In one example, the fatty acid is substantially whole cut. Additionally, at least one fatty acid source may be substantially entirely cleaved. Whole cleaved fatty acids are the product of direct fat splitting of natural oils and constitute substantially the natural fatty acid composition of representative natural oils. For purposes of this disclosure, whole cleaved fatty acids may be “cleaned” and/or partially fractionated, as would be understood by one skilled in the art. In addition, certain cuts, such as high melting point cuts, for purposes of illustration only and not intended to be limiting, may also be used. Suitable whole cleaved fatty acids are vegetable oils or seed oils such as coconut oil, palm oil, palm kernel oil, palm fatty acid distillates, soybean oil, jatropha oil, rapeseed oil, canola oil, high oleic soybean oil, It may be derived from sunflower oil, high oleic sunflower oil, corn oil, cottonseed oil, castor oil, olive oil, safflower oil or linseed oil. Also sources for fatty acids are fractionated or topped coconut oil, palm kernel oil, tallow or palm oil. Whole cleaved fatty acids can also be derived from animal oils such as fish oil, lard, beef tallow or whale oil. The oil may also contain polyfunctional fatty acids, which may be dicarboxylic acids, hydroxy functional acids, or epoxidized, maleated, metathesised, amidated, halogenated, hydrated, hydroformylated, dimerized, or It can consist of acids modified by techniques that can include, but are not limited to, estolide formation. In addition, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, undecylic acid, lauric acid, tridecylic acid, myristic acid, pentadecylic acid, palmitic acid , margaric acid, stearic acid, nonadecylic acid, arachidic acid, heneicosylic acid, behenic acid, oleic acid, linoleic acid and erucic acid. A fatty acid stream may be used. It is also understood that functional acids such as undecylenic acid are involved in this operation.

Fatty acids obtained by high pressure splitting of vegetable oils are distilled and can be fractionated into various fractions or individual cuts. Fractionation makes it possible to separate a mixture of fatty acids into narrower cuts or even into individual components. "Over the top" describes the removal of the lower boiling fraction from the fatty acid mixture. Also, the fatty acids may be from hydrogenated oils. The fatty acid may also be a dicarboxylic acid, such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid or octadecanedioic acid. .

More than one fatty acid may be used, and the fatty acid may be a functionalized acid. Functionalization of the fatty acids can occur before or after esterification with alkoxylated glycerol. Functionalization may include epoxidation, maleation, metathesis, amidation, halogenation, hydration, estolide formation, hydroformylation, dimerization or vulcanization. Specifically, the functionalized acid may be saturated or unsaturated, such as a saturated functionalized acid such as 12-hydroxystearic acid. The structure of fatty acids can also vary. Fatty acids can be branched, cyclic or aromatic. Branched fatty acids may include, but are not limited to, 2-ethylhexanoic acid or isostearic acid. The oil will have improved physical properties, including pour points below 0°C, preferably below -10°C, preferably below -20°C, preferably below -30°C and most preferably below -40°C. .

By using fatty acid(s) with alkoxylated glycerol(s), the present disclosure provides high biobased carbon content (>40%, such as >45, >50, >55, >60, >65, >70, >75, >80, >85, >90, >95 etc.) (Fig. 11, Table 10) and high biodegradability as determined by OECD 301B (>50%, e.g. >55 , >60, >65, >70, >75, >80, >85, >90, >95, etc.) (see FIG. 10, Table 9). Biobased carbon content refers to materials derived from biological products or renewable domestic agricultural materials (including plant, animal and marine materials) or forestry materials or intermediate feedstocks or agricultural by-products such as soap raw materials. In the production of bio-based oils, it is preferred that the polyols used to prepare the ester-based lubricants are of biogenic origin. For this reason, bioderived glycerol would be preferred. The lubricating base oil is at least 40% biobased carbon, such as 45%, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, etc. for purposes of illustration only and not intended to be limiting; Preferably the lubricating base oil is at least 50% biobased carbon, most preferably the lubricating base oil is at least 55% biobased carbon. Biodegradability refers to the ability of a material to be degraded by bacteria or other living organisms. The lubricating base oil is at least 50% biodegradable, such as 55%, 60, 65, 70, 75, 80, 85, 90, 95, etc. for illustrative purposes only and not intended to be limiting, more preferably a lubricating base oil. is at least 50% biodegradable, most preferably the lubricating base oil is at least 60% biodegradable. The lubricating base oil has a molecular weight of ≥500 g/mole, preferably ≥600 g/mole, preferably ≥700 g/mole, preferably ≥800 g/mole, most preferably ≥1000 g/mole, and a molecular weight of ≥160 g/mole. , For example, it may have a viscosity index of 165, 170, 175, 180, 185, 190, 195, 200 or more. In addition, antioxidants, antiwear agents, anticorrosive agents, anti-sludge agents, antifoaming agents, demulsifiers, viscosity index improvers, detergents/dispersants, pour point depressants, alkalinity improvers, friction modifiers, seal swelling agents, metal deactivators/complexing agents and extreme pressure agents. The performance of the oil can be improved by incorporating additives. It is understood by those skilled in the art that there is a range of additives with varying degrees of effectiveness for improved performance, and this dependence includes base oil and whole oil formulations. Included among these additives will be those known to be effective as additives in triglyceride based, synthetic polyol ester based, polyalkylene glycol based or other Group I, II, III, IV or Group V based base oils.

The present disclosure provides a manufacturing method. For example, a method is provided for stabilizing the β-hydrogen of glycerol in a base oil, wherein the free hydroxyl groups of glycerol are alkoxylated with ethylene oxide, propylene oxide, butylene oxide or combinations thereof to form alkoxylated glycerol form The present disclosure also relates to synthetic ester lubricants with improved oxidative, thermal and hydrolytic stability comprising esters of alkoxylated glycerol having an average degree of alkoxylation of ≥3 and at least one fatty acid having ≥8 carbon atoms. provides base oil. The present disclosure also relates to synthetic ester lubricants with improved oxidative, thermal and hydrolytic stability comprising esters of alkoxylated glycerol having an average degree of alkoxylation of ≥3 and at least one fatty acid having ≥8 carbon atoms. provides base oil. Alkoxylated glycerol may also be propoxylated, preferably with a degree of propoxylation of 10. Additionally, the source for the at least one fatty acid may be substantially whole cleavage. The source for the fatty acids may be coconut oil, high oleic soybean oil, soybean oil, corn oil, canola oil, sunflower oil or rapeseed oil. The source for the fatty acids may be fractionated or tops coconut oil, palm kernel oil, beef tallow or palm oil. At least one fatty acid may be a dicarboxylic acid. Dicarboxylic acids may include adipic acid, azelaic acid or sebacic acid. At least one fatty acid may be a functionalized acid. Saturated functionalized acids may include 12-hydroxystearic acid, 2-ethylhexanoic acid or isostearic acid. Functionalization may include epoxidation, maleation, metathesis, amidation, halogenation, hydration, estolide formation, hydroformylation, dimerization or vulcanization. At least one fatty acid may be branched. Branched acids may include 2-ethylhexanoic acid or isostearic acid. The lubricating base oil may have a pour point of -10°C or lower. The lubricating base oil may be at least 60% biodegradable. The lubricating base oil may be at least 50% biobased. The molecular weight may be >1000 g/mole. The lubricating base oil may have a viscosity index of ≧160. The present disclosure also provides synthetic lubricants comprising a substantial portion of a synthetic ester lube base oil and may contain additives selected from antioxidants, antiwear agents, corrosion inhibitors, antisludge agents and/or extreme pressure agents. In addition, the present disclosure provides a lubricating base oil or blowing oil that can be reformed through an oxidation process at elevated temperatures.

The present disclosure may also provide a method for stabilizing the β-hydrogen of glycerol in a base oil, wherein the free hydroxyl groups of glycerol are alkoxylated with ethylene oxide, propylene oxide, butylene oxide, or a combination thereof to form an alkoxylation glycerol is formed. The base oil may comprise an ester of alkoxylated glycerol having an average degree of alkoxylation of ≥3 and at least one fatty acid having ≥8 carbon atoms, thereby having improved oxidative, thermal and hydrolytic stability. Alkoxylated glycerol may be propoxylated, preferably with a degree of propoxylation of 10. The source for the at least one fatty acid may be substantially whole cleavage. The source for the fatty acids may be coconut oil, high oleic soybean oil, soybean oil, corn oil, canola oil, sunflower oil or rapeseed oil. The source for the fatty acids may be fractionated or tops coconut oil, palm kernel oil, beef tallow or palm oil. At least one fatty acid may be a dicarboxylic acid. Dicarboxylic acids may include adipic acid, azelaic acid or sebacic acid. At least one fatty acid may be a functionalized acid. Functionalization and/or hydrogenation can occur before or after reacting the fatty acid to the ester.

Saturated functionalized acids may include 12-hydroxystearic acid, 2-ethylhexanoic acid or isostearic acid. Functionalization may include epoxidation, maleation, metathesis, amidation, halogenation, hydration, estolide formation, hydroformylation, dimerization or vulcanization. At least one fatty acid may be branched. Branched acids may include 2-ethylhexanoic acid or isostearic acid. The lubricating base oil may have a pour point of -10°C or lower. The lubricating base oil may be at least 60% biodegradable. The lubricating base oil may be at least 50% biobased. The molecular weight may be >1000 g/mole. The lubricating base oil may have a viscosity index of ≧160. The present disclosure also provides a synthetic lubricant that may include a synthetic ester lubricating base oil comprising additives selected from antioxidants, antiwear agents, corrosion inhibitors, anti-sludge agents and/or extreme pressure agents. The present disclosure also provides a blown oil comprising a synthetic ester lube base oil, wherein the lube base oil can be reformed through an oxidation process at elevated temperatures. Lubricating base oils can also be part of cosmetic formulations.

One aspect of the present disclosure relates to industrial lubricants: gear oil, R&O compressor oil, R&O turbine oil; Automotive oil: crankcase oil, transmission oil, gear oil; metal working fluid; marine lubricants; Greece; process oil; or the use of propoxylated glycerol esters as lubricating base oils either neat or as formulated products in dielectric fluids.

The present disclosure may also provide blown oil blends comprising partial or complete replacements of synthetic ester lube base oils, wherein the lube base oils are reformed through an oxidation process at elevated temperatures to produce heat stable high viscosity base oils. A typical blowing process involves heating the oil to 70-120° C. and passing air through the liquid. The modification results in the formation of C-O-C and C-C crosslinks, hydroxyl and carboxyl functional groups. Blowing oils can be used as additives, as thickeners or to impart surface active properties to formulations. They can provide characteristics such as lubricity, biodegradability, high flash point, thickening and low toxicity.

The lubricant composition of the present invention has utility in applications where the oil in service is in contact with the environment, particularly water, air and particulate contaminants. These applications include hydraulic fluids for mobile equipment, universal tractor fluids, gear and transmission oils for mining and forestry equipment. With improved hydrolytic and thermal oxidative stability, the lubricant composition of the present invention is suitable for applications subject to contamination. Additionally, along with bio-based and biodegradable compositions, the lubricant compositions of the present invention are suitable for applications with a high incidence of leakage and oil loss.

The lubricant composition of the present invention has particular utility as a turbine oil for hydraulic turbines. Currently, hydraulic turbines must utilize mineral-based oils as they provide desirable stability and longevity for the application as conventional bio-based and biodegradable oils do not meet the stability criteria. The oils of the present invention provide a high biobased content, are readily biodegradable, and have thermal oxidative stability equivalent to conventional mineral turbine oils such as Chevron GST and Shell Turbo T. Accordingly, specification and formulation development of the oils of the present invention provided initial data demonstrating the usefulness of the compositions as hydraulic turbine oils. Additional embodiments are illustrated in the following examples, which are provided for illustrative purposes only and are not intended to limit the scope of the present disclosure.

Example

Having now described embodiments of the present disclosure, generally the following examples describe some additional embodiments of the present disclosure. Embodiments of the present disclosure are described in connection with the following examples and corresponding text and figures, but there is no intention to limit the embodiments of the present disclosure to these descriptions. On the contrary, the intention is to cover all alternatives, modifications and equivalents included within the spirit and scope of the embodiments of this disclosure. The following examples are presented to provide those skilled in the art with a complete disclosure and explanation of how to perform the methods disclosed and claimed herein. Efforts have been made to ensure accuracy with respect to numbers (eg amounts, temperature, etc.) but some errors and deviations should be accounted for. Unless otherwise indicated, parts are parts by weight, temperature is in °C, and pressure is at or near atmospheric. Standard temperature and pressure are defined as 20° C. and 1 atm.

Method A: A suitable reaction vessel was charged with alkoxylated glycerol and 10% molar excess of the desired fatty acid(s). The esterification was carried out at 240-250° C. and was carried out under vacuum until the acid number of the reaction mixture was less than about 15 mg KOH/g and the hydroxyl value of the reaction mixture was less than about 20 mg KOH/g. Excess fatty acids and volatile reaction by-products were then removed via short path distillation under vacuum and elevated temperature. Conventional ester purification techniques can be used in the absence of short path distillation. The ester product of the reaction has an acid value of <1 mg KOH/g, preferably an acid value of <0.5 mg KOH/g, and a hydroxyl value of <10 mg KOH/g, preferably <5 mg KOH/g hydroxyl value. Transversely purified. An alkoxylated glycerol ester is considered a triester when a hydroxyl number of less than 15 mg KOH/g, or more preferably less than 10 mg KOH/g, or most preferably less than 5 mg KOH/g is achieved. .

Method B : An alkoxylated glycerol ester lubricating base oil of the present disclosure was prepared by charging an appropriate reaction vessel with alkoxylated glycerol, 10% molar excess of the desired fatty acid(s), and 0.5 mol% methanesulfonic acid. Esterification was carried out at 170° C. and was carried out under vacuum until the acid value of the reaction mixture was less than about 15 mg KOH/g and the hydroxyl value of the reaction mixture was less than about 10 mg KOH/g. Excess fatty acids and volatile reaction byproducts were then removed via short path distillation under vacuum and elevated temperature. Conventional ester purification techniques can be used in the absence of short path distillation. The ester product of the reaction has an acid value of <1 mg KOH/g, preferably an acid value of <0.5 mg KOH/g, and a hydroxyl value of <10 mg KOH/g, preferably <5 mg KOH/g hydroxyl value. Transversely purified.

Method C : An alkoxylated glycerol ester lubricating base oil of the present disclosure was prepared by charging an appropriate reaction vessel with alkoxylated glycerol, 0.1% molar depletion of the required fatty acid(s), and 0.5 mole% methanesulfonic acid. Esterification was carried out at 170° C. and was carried out under vacuum until the acid value of the reaction mixture was less than about 3 mg KOH/g and the hydroxyl value of the reaction mixture was less than about 10 mg KOH/g, at which point short-chain fatty acids The addition of (<C12) occurred and the reaction was continued until the hydroxyl value was less than 5 mg KOH/g. Excess fatty acids and volatile reaction byproducts were then removed via short path distillation under vacuum and elevated temperature. Conventional ester purification techniques can be used in the absence of short path distillation. The ester product of the reaction has an acid value of <1 mg KOH/g, preferably an acid value of <0.5 mg KOH/g, and a hydroxyl value of <10 mg KOH/g, preferably <5 mg KOH/g hydroxyl value. Transversely purified.

TMP is trimethylolpropane. PG## is the propoxylated glycerol ester with average degree of propoxylation = ##. C8-C10 are the fractions on top of the coconut oil. C12 is lauric acid. Pamolyn is a commercial fatty acid that is high in oleic acid and is derived from tall oil. BFT is oleic acid derived from high bleachable tallow. HOSO is high oleic soybean oil. SBO is soybean oil. EH is 2-ethylhexanoic acid. C18 Iso is isostearic acid. 12-HSA is 12-hydroxystearic acid. EG## is an ethoxylated glycerol ester with an average degree of ethoxylation = ##.

Examples 89 to 91 (see Figure 2): Proton NMR was performed to evaluate the strength of hydrogen bonds in glycerol, propoxylated glycerol esters and TMP base oils. The high electron density around the proton stabilizes its bonding to adjacent carbon atoms and correlates with NMR absorbance at lower ppm values. Electronegative groups attached to the CH system reduce the electron density around the protons and increase their chemical shift to higher ppm values. ¹ H NMR peaks (see FIG. 3, Table 2) of alpha-methine and beta-methylene protons of glycerol esters (see FIG. 1) show methylene and methine protons of the glycerol main chain on propoxylated glycerol esters (see FIG. 1) ( 1), indicating a shift to lower ppm, indicating an increase in electron density at these locations that correlates with a higher stability for the proton(s). The increased electron density observed from ¹ H NMR of propoxylated glycerol esters is due to the electron-donating nature of the ether linkage of the propoxy group. Protons with lower chemical shifts are less reactive and are expected to have greater thermal stability than their higher value counterparts. TMP was included as a reference due to its inherent thermal stability without beta protons.

Examples 98 and 103 (see Figure 4, Table 3): Rotary Pressure Vessel Oxidation Test to Evaluate Thermal Oxidation and Hydrolytic Stability of Natural Glycerol Esters, Propoxylated Glycerol Esters, and TMP Ester Base Oils as Specified in ASTM D2272 (RPVOT) was performed. No additives are added to the base oil, but the natural oil will have naturally occurring antioxidants. Example 98, an unsaturated propoxylated glycerol ester with a viscosity rating of 68, exhibited a RPVOT life of 28 minutes, whereas Example 103, a saturated propoxylated glycerol ester with a viscosity rating of 58, exhibited a RPVOT life of 31 minutes. had For comparison, soybean oil and canola oil were tested. The unsaturated propoxylated glycerol ester shows a 64% increase in RPVOT life compared to the best performing natural glycerol ester and the saturated propoxylated glycerol ester shows an 82% increase. Unexpectedly, the performance of propoxylated glycerol esters significantly exceeds the RPVOT lifetime of TMP trioleates. See Lubrication Science , 2015, 27(6), p 369.

Examples 91, 92, 103, 90 (see Figure 5, Table 4): In addition to thermal oxidation stability, hydrolytic stability is often seen as a weakness in ester base oils. Data for hydrolytic stability testing (ASTM D2619) of several saturated ester base oils can be seen in Table 4 (see Figure 5). Saturated esters were used to determine the inherent stability of the esters without confounding factors (unsaturation and secondary oxidation products). The propoxylated glycerol ester base oil samples (Examples 91 and 103) exhibit greater hydrolysis resistance than the glycerol esters (Example 92) and TMP esters (Example 90). Reduced hydrolysis indicates increased stability in the presence of water, heat and catalyst, supported by RPVOT life data.

In a combined cycle unit, the new design includes a steam, gas turbine and generator on a single shaft. Accordingly, the lubricant will need to withstand the operating conditions of steam (wet) and gas (high temperature). Reference [ Fuels and Lubricants Handbook , pp. 582-583].

Examples 90, 92-94: A decrease in melting enthalpy is observed for propoxylated glycerol esters and TMP esters compared to glycerol esters (FIG. 6, Table 5, FIG. 7, Table 6, and FIG. 8, Table 7 reference). Example 94 (PG10 derivative) has the largest reduction in melting enthalpy and lowest degree of undercooling relative to the C12 ester in FIG. 6, Table 5. DSC analysis was performed within the temperature range of -80 °C to 40 °C with cyclic cooling and heating rates of 5 °C/min. The DSC melt pyrolysis curves for each material were integrated as a function of temperature and normalized to the total enthalpy of melting to generate the percent solids index that is the basis for the data in the Solids @ Onset +T column. Solids @ Onset +5 and +10 °C The data below show the percentage of solids in the base oil when heated from the completely solid or crystalline state. At 10° C. above the onset temperature, both the glycerol ester (Example 92) and the neopentyl polyol ester (TMP) (Example 90) exhibit significant amounts of crystalline solids that could be expected to cause problems within a lubricating system. . Both glycerol and TMP esters exhibit higher degrees of supercooling and higher enthalpies of melting compared to similar propoxylated glycerol esters (see Figure 7, Table 6).

Examples 91, 95 to 98, 100, 107, 109: Changing the fatty acid component of the ester has a clear effect on the melting enthalpy, cloud point and pour point (see Figure 8, Table 7). A material that forms a well-defined crystalline structure appears opaque under visual inspection below the pour point. Less ordered or structured materials appear translucent or transparent when observed at temperatures below their pour point and require less heat to melt. Unexpectedly, the base oil of the present disclosure can be modified such that the solid structure of the material can range from an opaque crystalline solid to a transparent amorphous solid. This is done by propoxylation of glycerol and converting it to mono- and polyunsaturated fatty acids (Examples 98 and 100), low-melting saturated fatty acids (Example 91), branched fatty acids (Example 107) and/or diacids (Example 109 ) is achieved by esterification with It is important to note that there are applications that require lubricants and greases to maintain transparency in cold climates. The clear solid allows inspection of oil or grease applied items. This is found to be useful in applications in wire rope lubrication where it is important that the wire can be inspected for damage. Also in these applications, it is usually desirable that the lubricant or grease be an environmentally acceptable lubricant.

Examples 90, 98-104 (see FIG. 9, Table 8): Representative base oils derived from propoxylated glycerol (PG10) and whole cleavage or substantially whole cleaved fatty acid sources. All examples have pour points and viscosities representative of lubricating base oils in ISO VG 46-68 and SAE30. All samples exhibit very high viscosity indices (>180) and Examples 91, 98 and 100 remain clear below their pour point as indicated by no cloud point observed.

Example 103 (see Figure 10, Table 9): Example 103, one iteration of the base oil of the present disclosure, was tested for biodegradability according to OECD 301B. The sample was found to exhibit "ready biodegradability in aerobic aqueous media" with a biodegradation of 61% at the end of the 10 day period.

Examples 103 and 98 (FIG. 11, Table 10): Bio-based carbon analysis. Examples 103 and 98 were characterized using ASTM method D6866-20 to determine the % biobased carbon making up the base oil. Changes in biobased carbon content are based on alkoxylation degree and fatty acid carbon number.

Examples 105-109 (FIG. 12, Table 11): Base oils utilizing branched, functional and discrete species to modify the physical properties of the base oil. All examples maintain low pour points, representative viscosities and high viscosity indices. Examples 107-109 expand the potential range of applications as they are matched with ISO VG 100 and 150 oils. Higher viscosity oils would be prime candidates as base oils for greases and gear oils.

Example 103 (formulated) (see FIG. 13, Table 12): Example 103, one iteration of the base oil of the present disclosure, was prepared in a turbine oil and a hydraulic/universal tractor fluid (additive package supplied by Tiarco Chemical and King Industries, respectively). ) was formulated using a commercially available antioxidant, corrosion inhibitor and antiwear additive package for use as The two formulations of the base oil were then tested using conventional bench tests, soybean oil formulated using Chevron GST (ISO VG 68) and King Industries NA-Lube BL-1208 additive system and formulated Compared to canola oil. Chevron GST is included as an industry-leading turbine oil suitable for use in gas, steam and hydraulic turbines as well as hydraulic controls in hydroelectric power plants.

Examples 110-112 (see Figure 14, Table 13): Ethoxylated Glycerol Esters Properties. Ethoxylated glycerol (EG12, Lumulse 12 from Vantage Oleochemical) whose molecule has an average of 12 ethoxy groups was esterified with coconut fatty acid (Example 110), lauric acid (Example 11) via Method A. Table 13 compares ethoxylated glycerol esters to propoxylated glycerol esters with similar fatty acid sources. Example 112 is a propoxy-ethoxylated glycerol ester trioleate prepared using Method A. EO capped propoxylated glycerol (PG10EGc, Carpol 725 from Carpenter Chemical) is glycerol with an average of 10 propoxy groups, where each terminal propoxy group is capped with one ethoxy group (3 EO per molecule). .

Various modifications and variations of the described methods and compositions will be apparent to those skilled in the art without departing from the scope and spirit of this disclosure. Although the disclosure has been described with reference to specific implementations, it will be understood that further modifications are possible and that the disclosure as claimed should not be unduly limited to such specific implementations. Indeed, various modifications of the described modes for carrying out the present disclosure that would be obvious to those skilled in the art are intended to be within the scope of the present disclosure. This application generally follows the principles of the disclosure and does not apply to any of the disclosures to which the disclosure relates and including such departures from the disclosure that are within known customary practice within the art as may be applied to the essential features set forth hereinbefore. It is intended to cover variations, uses or adaptations.

Claims (22)

As a synthetic ester lubricating base oil,
Esters of alkoxylated glycerol with an average degree of alkoxylation of ≧3;
contains at least one fatty acid having ≧8 carbon atoms;
Compared to glycerol esters having the same fatty acid composition, the synthetic ester lubricating base oil has
increased oxidative, thermal or hydrolytic stability;
reduced enthalpy of melting; and
Synthetic ester lube base oils exhibiting reduced undercooling. 2. The synthetic ester lube base oil according to claim 1, wherein the thermal oxidation stability of the synthetic ester lube base oil is increased by more than 25% as determined by RPVOT life compared to glycerol esters of the same fatty acid composition. 2. A synthetic ester lubrication according to claim 1, wherein the hydrolytic stability of the synthetic ester lubricating base oil is improved as measured by a reduction in total acid value number by greater than 50% relative to glycerol esters having the same fatty acid composition. base oil. 2. A synthetic ester lubricating base oil according to claim 1, wherein the melting enthalpy is reduced by more than 50% relative to a glycerol ester having the same fatty acid composition. 2. The synthetic ester lube base oil according to claim 1, wherein the melting enthalpy is reduced such that the synthetic ester lube base oil exhibits no detectable cloud point and remains clear. 2. The synthetic ester lubricating base oil according to claim 1, wherein the undercooling is reduced by more than 30% for glycerol esters having the same fatty acid composition. 2. The synthetic ester lubricating base oil of claim 1, wherein the alkoxylate is derived from ethylene oxide, propylene oxide, butylene oxide or a combination thereof. 8. A synthetic ester lubricating base oil according to claim 7, wherein the alkoxylated glycerol is a propoxylated glycerol having 3 to 20 propoxy groups. The synthetic ester lubricating base oil according to claim 1, wherein the at least one fatty acid is a dicarboxylic acid. The synthetic ester lubricating base oil according to claim 1, wherein the at least one fatty acid is a linear saturated or unsaturated acid. 2. The synthetic ester lubricating base oil of claim 1, wherein the at least one fatty acid is derived from whole cut or partially whole cut fatty acids. The synthetic ester lubricating base oil according to claim 1, wherein the at least one fatty acid is a functionalized acid. The synthetic ester lubricating base oil according to claim 1, wherein the at least one fatty acid is branched. The synthetic ester lube base oil according to claim 1, wherein the synthetic ester lube base oil is at least 50% biodegradable in the 10-day window of the OECD 301B test. 2. The synthetic ester lube base oil of claim 1, wherein the synthetic ester lube base oil is at least 40% biobased carbon. A synthetic lubricant comprising the synthetic ester lubricating base oil of claim 1 comprising at least one additive, wherein the at least one additive is an antioxidant, an antiwear agent, an anticorrosive agent, an anti-sludge agent, an antifoaming agent, and a demulsifying agent. , a synthetic lubricant selected from viscosity index improvers, detergents/dispersants, pour-point depressants, alkalinity improvers, friction modifiers, seal swelling agents, metal deactivators/complexing agents and/or extreme pressure agents. 17. The synthetic ester lubricating base oil of claim 16, having a thermal oxidation stability of greater than 600 minutes as determined by RPOVT life. The synthetic ester lubricating base oil according to claim 1, further comprising a hydrolytically stable biodegradable lubricant. 19. The method of claim 18, wherein the alkoxylated glycerol ester has hydrolytic stability and biodegradability by tailoring ester bond stability and ester density through the use of alkoxylation, and the degradation products of the alkoxylated glycerol ester are non-toxic. Synthetic ester lubricating base oil. 19. The synthetic ester lube base oil according to claim 18, wherein the lubricant viscosity is 32 to 150 mm ² /s. A process using alkoxylation to stabilize the beta hydrogens of glycerol esters and dilute the molar density of ester linkages in ester base oils to form alkoxylated glycerol esters that are thermally, oxidatively and hydrolytically stable, wherein the hydroxyl of glycerol wherein the groups are alkoxylated with ethylene oxide, propylene oxide, butylene oxide or combinations thereof. The synthetic ester lubricating base oil of claim 1 further comprising an ester of alkoxylated glycerol having an average degree of alkoxylation of ≧5.