Production of oligoamides and uses thereof

Abstract

A method is disclosed for making an oligoamide by a) contacting an at least partially aromatic diacid and an aliphatic diamine under conditions sufficient to at least partially convert the at least partially aromatic dicarboxylic acid and the aliphatic diamine to a first crude product comprising a salt. A method may b) separate excess aliphatic diamine from the first crude product of (a) and react the recovered salt with a long-chain fatty acid to produce a second crude product. A method may c) recover oligoamide from the crude product of step (b).

Description

PRODUCTION OF OLIGOAMIDES AND USES THEREOFCLAIM OF PRIORITY

[0001] This patent application claims the benefit of priority to U.S. Provisional Application Serial No. 63 / 674,295, filed July 23, 2024, which is incorporated by reference herein in its entirety.BACKGROUND

[0002] Polyamide synthesis can include the formation of polymers through the polycondensation reaction of diamines with di carboxylic acids or the ring-opening polymerization of lactams. This process yields materials known for their exceptional strength, thermal stability, and resistance to wear, making them useful in various industries including automotive, aerospace, textiles, and consumer goods. Innovations in polyamide synthesis focus on enhancing these properties while also improving the environmental footprint of production processes. Such advancements can contribute to the development of high-performance materials that meet stringent industry standards and support sustainability initiatives.SUMMARY

[0003] In some aspects, the techniques described herein relate to a method for making an oligoamide including: a) contacting an at least partially aromatic diacid and an aliphatic diamine under conditions sufficient to at least partially convert the at least partially aromatic dicarboxylic acid and the aliphatic diamine to a first crude product including a salt; b) separating excess aliphatic diamine from the first crude product of (a) and reacting the recovered oligomeric salt with a long-chain fatty acid to produce a second crude product; and c) recovering oligoamide from the crude product of step (b).

[0004] In some aspects, the techniques described herein relate to a method for making an oligoamide grease thickening including: a) contacting an at least partially aromatic diacid and an aliphatic diamine under conditions sufficient to at least partially convert the at least partially aromatic dicarboxylic acid and the aliphatic diamine to a first crude product including a salt in the absence of added halogen-containing feed; b) separating excess aliphatic diamine from the first crude product of (a) and reacting the recovered oligomericsalt with a long-chain fatty acid to produce a second crude product; and c) recovering oligoamide from the crude product of step (b).

[0005] In some aspects, the techniques described herein relate to a method of making an oligoamide grease thickening agent; the method including the steps of: contacting an aromatic dicarboxylic acid and a diamine in a first reaction zone; maintaining the conditions in the first reaction zone to obtain a first reaction product; recovering the first reaction product from the first reaction zone; contacting the first reaction product from with a long- chain fatty acid; maintaining the conditions in the second reaction zone to obtain a second reaction product; and recovering the second reaction product from the second reaction zone; wherein, the second reaction product is characterized as the oligoamide grease thickening agent including at least two para-substituted aromatic moieties, have a molecular weight in a range of from 450 g / mol to 3500 g / mol, and at least four amide bonds.DETAILED DESCRIPTION

[0006] Reference will now be made in detail to certain aspects of the disclosed subject matter, examples of which are illustrated in part in the accompanying drawings. While the disclosed subject matter will be described in conjunction with the enumerated claims, it will be understood that the exemplified subject matter is not intended to limit the claims to the disclosed subject matter.

[0007] Throughout this document, values expressed in a range format should be interpreted in a flexible manner to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. For example, a range of “about 0.1% to about 5%” or “about 0.1% to 5%” should be interpreted to include not just about 0.1% to about 5%, but also the individual values (e.g., 1%, 2%, 3%, and 4%) and the sub-ranges (e.g., 0.1% to 0.5%, 1.1% to 2.2%, 3.3% to 4.4%) within the indicated range. The statement “about X to Y” has the same meaning as “about X to about Y,” unless indicated otherwise. Likewise, the statement “about X, Y, or about Z” has the same meaning as “about X, about Y, or about Z,” unless indicated otherwise.

[0008] In this document, the terms “a,” “an,” or “the” are used to include one or more than one unless the context clearly dictates otherwise. The term “or” is used to refer to a nonexclusive “or” unless otherwise indicated. The statement “at least one of A and B” or “at least one of A or B” has the same meaning as “A, B, or A and B.” In addition, it is to beunderstood that the phraseology or terminology employed herein, and not otherwise defined, is for the purpose of description only and not of limitation. Any use of section headings is intended to aid reading of the document and is not to be interpreted as limiting; information that is relevant to a section heading may occur within or outside of that particular section. A comma can be used as a delimiter or digit group separator to the left or right of a decimal mark; for example, “0.000,1” is equivalent to “0.0001.” All publications, patents, and patent documents referred to in this document are incorporated by reference herein in their entirety, as though individually incorporated by reference. In the event of inconsistent usages between this document and those documents so incorporated by reference, the usage in the incorporated reference should be considered supplementary to that of this document; for irreconcilable inconsistencies, the usage in this document controls.

[0009] In the methods described herein, the acts can be carried out in any order without departing from the principles of the disclosure, except when a temporal or operational sequence is explicitly recited. Furthermore, specified acts can be carried out concurrently unless explicit claim language recites that they be carried out separately. For example, a claimed act of doing X and a claimed act of doing Y can be conducted simultaneously within a single operation, and the resulting process will fall within the literal scope of the claimed process.

[0010] The term “about” as used herein can allow for a degree of variability in a value or range, for example, within 10%, within 5%, or within 1% of a stated value or of a stated limit of a range, and includes the exact stated value or range.

[0011] The term “substantially” as used herein refers to a majority of, or mostly, as in at least about 50%, 60%, 70%, 80%, 90%, 95%, 96%, 97%, 98%, 99%, 99.5%, 99.9%, 99.99%, or at least about 99.999% or more, or 100%. The term “substantially free of’ as used herein can mean having none or having a trivial amount of, such that the amount of material present does not affect the material properties of the composition including the material, such that about 0 wt% to about 5 wt% of the composition is the material, or about 0 wt% to about 1 wt%, or about 5 wt% or less, or less than or equal to about 4.5 wt%, 4, 3.5, 3, 2.5, 2, 1.5, 1, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, 0.1, 0.01, or about 0.001 wt% or less, or about 0 wt%.

[0012] The term “a salt”, as used herein, refers to a class of ammonium carboxylate salts. Non-limiting examples may include salts formed from a partially aromatic polycarboxylic acid (PCA) and an aliphatic diamine (DA). One example may be a salt formed from terephthalic acid (PTA or commonly known as “T”) and hexamethylenediamine(HMD). Another example may be a salt formed from isophthalic acid (PIA or commonly known as “I”) and hexamethylenediamine (HMD).

[0013] The terms “oligoamide” and its plural form “oligoamides”, as used herein, refer to a class of chemical compounds having several amide groups. The amide group is characterized with the chemical structure of -CONH2.

[0014] As used herein, the parameters, Po, Peo, P 10000 and P 100000, represent the degree to which a grease composition is worked. For example, a grease composition that is unworked has a Po value. A grease composition that is inserted into a container and has a plunger stroked 60 times while the test apparatus and grease composition are maintained at a temperature of 25 °C has a Peo value. A grease composition that is inserted into a container and has a plunger stroked 10000 times while the test apparatus and grease composition are maintained at a temperature of 25 °C has a P10000 value. A grease composition that is inserted into a container and has a plunger stroked 100000 times while the test apparatus and grease composition are maintained at a temperature of 25 °C has a P100000 value.

[0015] The mechanical strength of the grease compositions can be assessed from the NLGI consistency number determination as per the ASTM D-217 method. An NLGI consistency number of an unworked composition (a sample that has received only minimal disturbance) of the grease composition can be in a range of 3 to 4. An NLGI consistency number of the worked grease composition (as sample that has been subjected to 60 double strokes in a standard grease worker) can be in a range of 1 to 2.

[0016] The NLGI consistency number measurement is titled “cone penetration of lubricating grease" following the ASTM D-217 method. This involves two test apparatus. The first apparatus consists of a closed container and a piston-like plunger. The face of the plunger is perforated to allow grease to flow from one side of the plunger to another as the plunger is worked up and down with a grease worker. The test grease is inserted into the container and the plunger is stroked 60 times while the test apparatus and grease are maintained at ambient conditions. Once worked, the grease is placed in a penetration test apparatus, a penetrometer. This apparatus includes a container, a specially configured cone and a dial indicator. The container is filled with the grease and the top surface of the grease is smoothed over. The cone is placed so that its tip is as close as possible without touching the grease surface and the dial indicator is set to zero at this position. When the test starts, the weight of the cone will cause it to penetrate into the grease. After a specific time interval, the depth of penetration is measured.

[0017] Various aspects of the present disclosure relate to an oligoamide and a method of making the oligoamide. While not so limited, the oligoamide can be used as a grease thickening agent. The method of making the oligoamide generally includes contacting an at least partially aromatic polycarboxylic acid (PCA) and an aliphatic diamine (DA) under conditions sufficient to at least partially convert the at least partially aromatic polycarboxylic acid and the aliphatic diamine to a first crude product comprising a salt. The method further includes separating excess aliphatic diamine from the first crude product and reacting the recovered oligomeric salt with a long-chain fatty acid (e.g., a monocarboxylic acid (MCA)) to produce a second crude product. The method further includes recovering oligoamide from the crude product.

[0018] As an example, the oligoamide can have the structure according to Formula I:(MCA-DA-)(PCA-DA)y-PCA-(DA-PCA)y(-DA-MCA) (I).In still further examples, the oligoamide can have the structure according to Formula II:((MCA-DA-)(PCA-DA)y-)nPCA (II).In Formula II, n is in a range of from 2-4. In still further examples, the oligoamide has the structure according to Formula III:(MCA-DA)-PCA-(DA-MCA) (III).

[0019] The reacted polycarboxylate can be a polycarboxylic acid, polycarboxylic ester, or an anhydride. Non-limiting examples of polycarboxylic acids may also include benzene-tri-carboxylic acid, tetra-acids, naphthalenic polyacids, and 1, l'-Biphenyl]-3,3',5,5'- tetracarboxylic acid.

[0020] At each occurrence, PCA can independently include 3 to 50 carbon atoms 6 to 10 carbon atoms, or 6, 8, or 9 carbon atoms. For example, at each occurrence, PCA can include a reacted poly carboxylate having the structure according to the following Formulas:Formula (IV):Formula (V):

[0021] At each occurrence R1and R2are independently a bond or a substituted or unsubstituted (Ci-C2o)hydrocarbyl and at each occurrence, R6is chosen from -OH, -O', or substituted or unsubstituted -0-(Ci-C2o)hydrocarbyl. At each occurrence the substituted or unsubstituted (Ci-C2o)hydrocarbyl is independently selected from a substituted or unsubstituted (Ci-C2o)alkyl, a substituted or unsubstituted (C3-C2o)cycloalkyl, a substituted or unsubstituted (C2-C2o)alkenyl, a substituted or unsubstituted (C2-C2o)alkynyl, a substituted or unsubstituted (Ci-C2o)acyl, a substituted or unsubstituted (C4-C2o)aryl, and a substituted or unsubstituted (C2-C2o)alkoxy. In some examples, at each occurrence, PCA has the same chemical structure. Alternatively, at least two occurrences PCA can have different chemical structures.

[0022] As specific examples, at each occurrence, PCA independently includes a reacted adipic acid, a reacted purified terephthalic acid, a reacted isophthalic acid, a reactedphthalic anhydride, a reacted phthalic acid, a reacted napthalenic acid, a reacted mellitic acid, a reacted mellitic anhydride, a reacted naphthalene tetracarboxylic anhydride, a reacted citric acid, a reacted ester, a reacted acid chloride, a reacted dianhydride, or a reacted ethylenediaminetetraacetic acid. PCA can include three carboxylic acid groups or two carboxylic acid groups. In some examples, PCA is preferred to have two carboxylic acids. Moreover, PCA will not include a reacted acid chloride or polyacid chloride.

[0023] The PCA can have a weight-average molecular weight in a range of up to about 200 g / mol.

[0024] At each occurrence, MCA can include a reacted ester, or a reacted anhydride. For example, at each occurrence MCA can include a reacted monocarboxylate, the monocarboxylate having the structure according to Formula (VI):In Formula VI, R3is a substituted or unsubstituted (Ci-C4o)hydrocarbyl and R7is chosen from -OH, -O', or substituted or unsubstituted -0-(Ci-C2o)hydrocarbyl. At each occurrence the substituted or unsubstituted (Ci-C4o)hydrocarbyl is independently selected from a substituted or unsubstituted (Ci-C4o)alkyl, a substituted or unsubstituted (C3-C4o)cycloalkyl, a substituted or unsubstituted (C2-C4o)alkenyl, a substituted or unsubstituted (C2-C4o)alkynyl, a substituted or unsubstituted (Ci-C4o)acyl, a substituted or unsubstituted (C4-C4o)aryl, and a substituted or unsubstituted (C2-C4o)alkoxy.

[0025] As a further example, at each occurrence MCA can include a reacted monocarboxylate. The monocarboxylate can have the structure according to the following Formulas:Formula (VII):Formula (VIII):Formula (IX):(IX).R4is chosen from a bond and a substituted or unsubstituted (Ci-C4o)hydrocarbylene. At each occurrence the substituted or unsubstituted (Ci-C4o)hydrocarbylene is independently selected from a substituted or unsubstituted (Ci-C4o)alkylene, a substituted or unsubstituted (C3- C2o)cycloalkylene, a substituted or unsubstituted (C2-C4o)alkenylene, a substituted or unsubstituted (C2-C4o)alkynylene, a substituted or unsubstituted (Ci-C4o)acylene, a substituted or unsubstituted (C4-C4o)arylene, and a substituted or unsubstituted -0-(CH2)n- (n = 2-40). At each occurrence MCA has the same chemical structure. Alternatively, at least two occurrences of MCA has a different chemical structure. As examples, MCA can be a reacted benzoic acid, a reacted cyclohexanecarboxylic acid, or a reacted steric acid. MCA will not be a reacted acid chloride.

[0026] Although not intending to be bound to any theory, it is believed that an oligoamide grease thickening agent in which MCA includes an aromatic group, cycloaliphatic group, or aliphatic group, provides the best performance for the grease thickening agent in the grease composition. In particular, it is thought that a second MCA including an aliphatic chain having 6-8 carbon atoms yields superior performance. The hydrophobic properties of the aliphatic groups are thought to aid in providing compatibility with the grease. It is also thought that if R3and R4are not a bond, then it is better for them to be n-(Ci-C4o)alkylene as this more easily allows for forming an oligoamide having the combination of the desirable structural features described herein above.

[0027] At each occurrence, the DA is a reacted diamine, independently having the structure according to Formula (IX):R5is a substituted or unsubstituted (Ci-C2o)hydrocarbylene. At each occurrence, the substituted or unsubstituted (Ci-C2o)hydrocarbylene is independently selected from a substituted or unsubstituted (Ci-C2o)alkylene, a substituted or unsubstituted (C3- C2o)cycloalkylene, a substituted or unsubstituted (C2-C2o)alkenylene, a substituted or unsubstituted (C2-C2o)alkynylene, a substituted or unsubstituted (Ci-C2o)acylene, a substituted or unsubstituted (C4-C2o)arylene, and a substituted or unsubstituted (C2- C2o)alkoxyene. At each occurrence DA has the same chemical structure. Alternatively, at least two occurrences of DA have a different chemical structure.

[0028] In specific examples, at each occurrence DA is a reacted diamine independently selected from a reacted hexamethylenediamine, a reacted propanediamine, a reacted butanediamine, a reacted pentanediamine, a reacted nonanediamine, a reacted isononanediamine, a reacted 2-methylpentamethylenediamine, a reacted ethylenediamine, a reacted isophorone diamine, a reacted m-xylylenediamine, and a reacted m- phenylenediamine. In some examples at each occurrence DA is a reacted hexamethylenediamine. In still more specific examples, it was found that internal aliphatic groups that are n— (Ci-C2o)alkylene yielded an oligoamide grease thickening agent that had desirable dropping point and NLGI properties. Typically, the DA does not include a branched structure. This is because diamines having a branched structure tend to make the grease composition to which the oligoamide grease thickening agent is included too soft which in turn lowers the melting point of the grease composition too much. In some examples, DA can be selected from a reacted hexamethylenediamine, a reacted propanediamine, a reacted butanediamine, a reacted pentanediamine, or a reacted nonanediamine.

[0029] The oligoamide can be present as a distribution. In the distribution, a weightaverage molecular weight of the oligoamide is in a range of from about 400 g / mol to about 10,000 g / mol, about 1100 g / mol to about 8,000 g / mol, about 1200 g / mol to about 4000 g / mol, less than, equal to, or greater than, 400 g / mol, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, 1000, 1050, 1100, 1150, 1200, 1250, 1300, 1350, 1400, 1450 1500, 2000, 2500, 3000, 3500, 4000, 4500, 5000, 5500, 6000, 6500, 7000, 7500, 8000, 8500, 9000, 9500, or about 10000 g / mol. Keeping the weight-average molecular weight in this range can help the oligoamide grease polymer to be classified as a polymer for regulatory purposes under 40 CFR 723.250(b). In specific examples it was found that a weight-average molecular weight in range of from about 450 g / mol to about 3500 g / mol or about 500 g / mol to about 2500 g / mol yielded an oligoamide with particularly advantageous properties (e.g., dropping point andNLGI values). Additionally, it was found that if the weight-average molecular weight of the oligoamide if used as a grease thickening component is too high, it will not be compatible with the base oil of the grease composition. Non-compatibility is established if the grease composition is not homogenous. A grease composition is considered to be homogenous if when examined under a microscope at 200 magnification, there are discrete particles observed.

[0030] The oligoamide is formed by contacting the at least partially aromatic polycarboxylic acid and aliphatic diamine under conditions sufficient to at least partially convert the at least partially aromatic polycarboxylic acid and the aliphatic diamine to a first crude product. The first crude product is a salt.

[0031] Notably, the oligomeric salt is free of any added halogen-containing feed as the aromatic diacid. Previous methods, which the instantly disclosed method is an improvement of, would require that a halogen-containing compound (e.g., an acid chloride) is used in production of the oligoamide. For example, terephthaloyl chloride is commonly used. However, terephthaloyl chloride (and other halogen containing compounds) can have several drawbacks. For example, terephthaloyl chloride has a relatively high cost relative to terephthalic acid. Moreover, terephthaloyl chloride is moisture sensitive, and requires dry solvents such as acetonitrile. Using acetonitrile requires additional steps relative to the instantly disclosed method, for example acetonitrile will require a sequential multi-column distillative system to first separate out the diamine / oligomers from the acetonitrile / H2O followed by -azeotropic separation of acetonitrile and H2O.

[0032] Moreover, using terephthaloyl chloride (or another acid chloride to react with a diamine) results in the liberation or hydrochloric acid by virtue of the reaction of terephthaloyl chloride and the diamine. The chlorides presence in the process creates equipment metallurgy challenges. Additionally, the chlorides must be reduced in the produced oligoamide (e.g., grease thickening agent) so as not to cause corrosion in end use applications. The chlorides removal would be achieved through washing with caustic solution followed by water, which creates the problem of handling and disposing the chlorides containing caustic wash streams. However, the instantly disclosed method avoids need using halogenated forms of the polycarboxylic acids and avoids the aforementioned drawbacks.

[0033] The conditions can include contacting the at least partially aromatic polycarboxylic acid and aliphatic diamine in an aqueous solvent. The aqueous solvent can be pure water or a mixture including water.

[0034] Further conditions include contacting the at least partially aromatic polycarboxylic acid and aliphatic diamine in an extruder. The extruder can be a twin screw extruder. The twin screw extruder can include a plurality of heating zones. The plurality of heating zones can be independently maintained at a temperature ranging from about 230 °C to about 300 °C, about 250 °C to about 275 °C, less than, equal to, or greater than about 230 °C, 235, 240, 245, 250, 255, 260, 265, 270, 275, 280, 285, 290, 295, or about 300 °C. The temperature across the plurality of zones can increase relative to an upstream zone. The increase in one zone temperature can range from about 5% to about 40% relative to a zone immediately upstream of it, or about 10% to about 30%, less than, equal to, or greater than about 5%, 10, 15, 20, 25, 30, 35, or about 40%. The total reaction time can range from about 30 minutes to about 15 hours, about 30 minutes to about 12 hours, less than, equal to, or greater than about 30 minutes, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or about 12 hours.

[0035] After the reaction between the at least partially aromatic polycarboxylic acid and aliphatic diamine is halted, any excess the at least partially aromatic polycarboxylic acid and aliphatic diamine is washed away leaving a first crude product behind. The first crude product is reacted with the long-chain fatty acid to produce a second crude product that includes the oligoamide. The oligoamide is recovered from the constituents of the second crude product.

[0036] A pH measured at any point during the reaction will be in a range of from about 6.5 to about 13, about 7 to about 13, less than, equal to, or greater than about 6.5, 6.6, 6.7, 6.8, 6.9, 7, 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, 8, 8.1, 8.2, 8.3, 8.4, 8.5, 8.6, 8.7, 8.8, 8.9, 9, 9.1, 9.2, 9.3, 9.4, 9.5, 9.6, 9.7, 9.8, 9.9, 10, 10.1, 10.2, 10.3, 10.4, 10.5, 10.6, 10.7, 10.8, 10.9, 11, 11.1, 11.2, 11.3, 11.4, 11.5, 11.6, 11.7, 11.8, 11.9, 12, 12.1, 12.2, 12.3, 12.4, 12.5, 12.6, 12.7, 12.8, 12.9 or about 13. As described herein the instant method avoids the liberation of acids such as a hydrochloric acid, thus the pH at any step of the method is approximately neutral or at least not acidic.

[0037] As mentioned herein the oligoamide can be grease thickening agent, which can be a component of a grease composition. A grease composition is generally understood to refer to a solid or semi-solid lubricant formed as a dispersion of thickening agents in a liquid lubricant. Grease compositions include a base oil (or lubricating oil), grease thickening agent, and optional additives. The grease thickening agent can be in a range of from about 1 wt% to about 50 wt% of the grease composition about 5 wt% to about 20 wt% of the grease composition. Base oils can include a vegetable oil, a mineral oil, synthetic oil, or any otherfluid that provides lubricating properties. As an example, the grease can be a silicone grease. A silicone grease can include a poly dimethy siloxane base oil. Other greases can be a fluoroether-based grease that includes a fluoroether base oil.

[0038] The oligoamide grease thickening agent, prepared according to the disclosed process, may be relatively inert to reacting with other components of a grease composition. Thus, the grease thickening agent can remain in the grease composition in an unreacted form. Moreover, the amide bond is less likely to be susceptible to hydrolysis. Thus, the grease thickening agent can tolerate some level of water that may present in the grease composition. Additionally, the grease thickening agent can be synthesized in the presence of water. These benefits are particularly apparent compared to a oligoamide grease thickening agent having terminal ester groups. The terminal ester groups may be more likely to react with other grease components or undergo hydrolysis, either of which can reduce the effectiveness of the oligoamide grease thickening agent.

[0039] Surprisingly and unexpectedly, the grease thickening agent, made according to the present disclosure, are able to perform at least substantially equivalently to a corresponding grease thickening agent that includes lithium, polyurea, or both. Thus, it is possible to formulate grease compositions that are substantially free of lithium, polyurea, or both.EXAMPLE

[0040] Various aspects of the present disclosure can be better understood by reference to the following Examples which are offered by way of illustration. The present disclosure is not limited to the Examples given herein.

[0041] Unless otherwise stated, all values and percents are on the weight (mass) basis.

[0042] The terms “6T”, “6T salt” or “6T nylon salt”, as used herein, refer to a salt prepared from terephthalic acid, an aromatic dicarboxylic acid, and hexamethylenediamine, an aliphatic diamine.

[0043] Terephthalic acid is abbreviated as “TA” or “PTA” or “T”.

[0044] Hexamethylenediamine is abbreviated as “HMD” or “HMD A” or “6”.

[0045] The terms, “oligoamide” and “oligoamides”, as used herein mean a single chain-like molecule or mixture of such chain-like molecules containing between 2 to 20 amide groups, though not necessarily limited to that range.

[0046] The term, “6T oligomer mix”, as used herein may refer to a mixture of oligoamides comprising the following constituents:

[0047] As an example, constituent (XI) is an oligoamide containing two amide (-CONH-) groups, while, constituent (XV) is an oligoamide containing ten amide (-CONH-) groups.Example 1

[0048] A stirred 50% solution of hexamethylenediamine in water is maintained at 80 °C. A 50% slurry of terephthalic acid in water was introduced dropwise over the course of 1 hour to the hexamethylenediamine solution so that the molar ratio of the final solution of hexamethylenediamine to terephthalic acid was 6: 1. The resulting slurry was allowed to stir for 3 additional hours at 80 °C before being transferred out of the reactor. The solution was concentrated to half the volume and an equal volume of methanol was added. The resulting precipitate was filtered, and the solids were washed with 3 portions of methanol to yield a 6T salt. The material was dried in a vacuum oven prior to use in the next step. A melting point of the recovered material was 275 °C (matching literature values for 6T nylon salt).

[0049] A one-to-one by weight pre-milled mixture of a stearic acid and 6T salt was fed into a non-vented, 16-mm diameter twin-screw extruder at screw speed of 75 - 100 rpm. The reaction temperature within the screw was maintained at 250 - 275 °C (zones are typically, 18 °C, 46 °C, 65 °C, 132 °C, 250 °C (5 zones), 212 °C, 160 °C) throughout the ten heating zones while maintaining a discharge pressure of (13 Bar - 27 Bar). The material was maintained within the extruder for 15 - 45 minutes before passing through a die cooled under a nitrogen blanket. The material was analyzed at via NMR for conversion, MW, free stearic acid, final product purity and repeating units (n).Example 2

[0050] To a stirred 50% solution of HMD in water maintained at 80 °C, a 50% slurry of TPA in water was introduced dropwise over the course of 1 hour so that the molar ratio of the final solution of HMD to TPA was 4: 1. The slurry was allowed to stir for 3 additional hours at 80C before being transferred out of the reactor. The solution was condensed to half the volume and precipitated with methanol, The solids were collected and were washed with 3 portions of methanol to remove any free starting materials. The material was dried in a vacuum oven prior to use in the next step. Melting point: 275°C (matching literature values for 6T nylon salt).

[0051] As described in Example 1, the twin screw extrusion step was followed to obtain the product between stearic acid and the 6T salt. The material was analyzed by NMR for conversion, MW, free stearic acid, final product purity and repeating units (n).Example 3

[0052] To a stirred 50% solution of HMD in water maintained at 80°C in an autoclave, a 50% slurry of TPA in water is introduced dropwise over the course of 1 hour so that the molar ratio of the final mixture of HMD to TPA is 2: 1. The slurry is allowed to stir for up to 3 additional hours at 80°C before being heated. The mixture is heated and dewatered via distillation as the temperature is increased up to 280 °C under up to 20 bar gauge pressure and held for up to 60 minutes. The reaction may optionally contain a catalyst such as sodium hypophosphite or hypophosphorous acid. The contents of the autoclave are discharged into a spray drying chamber. The excess steam and other volatile components such as diamine are vented out of the chamber and condensed. The dried solids collected in the spray chamber are recovered and further dried to remove any residual volatile materials.The resulting white powder is a 6T oligomer mix containing constituents (XI) through (XV) as described above.

[0053] The dried oligomer mix is combined 1: 1.95 by molar ratio with stearic acid and allowed to mix via ball mill for 2 hours and then is fed into a non-vented twin-screw extruder at screw speed of 75 - 100 rpm. The reaction temperature within the screw is maintained at 250 - 275 °C (zones are typically, 18 °C, 46 °C, 65 °C, 132 °C, 250 °C (5 zones), 212 °C, 160 °C) throughout the ten heating zones while maintaining a discharge pressure of (13 bar - 27 bar). The material is maintained within the extruder for 15 - 45 minutes before passing through a die and cooled under a nitrogen blanket. The material is analyzed by NMR for conversion, MW, free stearic acid, final product purity and repeating units (n).Comparative Example 1

[0054] With a basis of 540g of HMD added to the first stage reaction vessel, 500 g of acetonitrile is added to the reaction vessel as initial charge. The reaction vessel cooling jacket flow and agitation are established. The reactor vessel head space is padded with nitrogen. 1355 g of 15% terephthaloyl chloride (TPC) in acetonitrile solution is then added over 120 minutes. The reaction vessel temperature is maintained at 50 °C. The reaction is completed an hour after final feeding of TPC. The total reaction time is three hours. The precipitate is separated from the reaction mixture and the wet cake is mixed with 2350g of 2.5% caustic solution. The caustic wash mixture is agitated for 1 hour at 50 °C. After the caustic wash step, the solids are filtered from the liquid. The material is washed twice with 2350g of water and dried resulting in 6T oligomer mix.

[0055] The above-prepared dried 6T oligomer mix was combined 1 : 1.95 by molar ratio with stearic acid and allowed to mix via ball mill for 2 hours and then was fed into a twin-screw extruder at screw speed of 75 - 100 rpm. The reaction temperature within the screw was maintained at 250 - 275°C (zones are typically, 18 °C, 46 °C, 65 °C, 132 °C, 250 °C (5 zones), 212 °C, 160 °C) throughout the ten heating zones while maintaining a discharge pressure of (13 bar - 27 bar). The material was maintained within the extruder for 15 - 45 minutes before passing through a die and cooled under a nitrogen blanket. The material was analyzed by NMR for conversion, MW, free stearic acid, final product purity and repeating units (n).

[0056] In this example, the use of TPC requires exotic equipment metallurgy that can handle the chlorides. In addition, the use of acetonitrile solvent and caustic solutions add cost and complexity to the process. The acetonitrile-water stream from the first step necessitates distillative column sequence to break and separate the azeotropic mixture. The caustic wash containing residual chlorides must be handled and properly treated for disposal.

[0057] TABLE 1 provides a summary of the final product analysis obtained in the above examples. Surprisingly, it was observed that the disclosed process produces a similar or near-equivalent final product as when TPC was used. The process simplicity and improvement are realized by avoiding the introduction of TPC.TABLE 1Example 4

[0058] The product of Example 2 is incorporated into a grease composition at 12 wt% concentration. The Dropping point of the grease composition is about 220 °C. Table 3 below summarizes the mechanical performance of grease composition prepared accordingly.TABLE 3Exemplary Aspects.

[0059] The following exemplary aspects are provided, the numbering of which is not to be construed as designating levels of importance:

[0060] Aspect 1 provides a method for making an oligoamide comprising: a) contacting an at least partially aromatic diacid and an aliphatic diamine under conditions sufficient to at least partially convert the at least partially aromatic dicarboxylic acid and the aliphatic diamine to a first crude product comprising a salt; b) separating excess aliphatic diamine from the first crude product of (a) and reacting the recovered oligomeric salt with a long-chain fatty acid to produce a second crude product; and c) recovering oligoamide from the crude product of step (b).

[0061] Aspect 2 provides the method of Aspect 1 wherein the dicarboxylic acid is selected from terephthalic acid and isophthalic acid.

[0062] Aspect 3 provides the method of Aspect 2 wherein the dicarboxylic acid is terephthalic acid.

[0063] Aspect 4 provides the method of any of Aspects 1-3 wherein the long-chain fatty acid is a Cs to C40 fatty acid.

[0064] Aspect 5 provides the method of Aspect 4 wherein the long-chain fatty acid is a C12 to C24 fatty acid.

[0065] Aspect 6 provides the method of Aspect 5 wherein the long-chain fatty acid has suitable properties for reacting with the oligomeric salt of Aspect 1 to form grease thickening agent.

[0066] Aspect 7 provides the method of Aspect 6 wherein the long-chain fatty acid is characterized by properties including melting point, hardness, solubility and oxidation stability for use as a grease thickening agent component.

[0067] Aspect 8 provides the method of any of Aspects 1-7, wherein the recovered oligomeric salt is reacted with a long-chain fatty acid in an extruder.

[0068] Aspect 9 provides the method of Aspect 8, wherein the extruder is a twin screw extruder.

[0069] Aspect 10 provides the method of Aspect 9, wherein the twin-screw extruder comprises a plurality of heating zones independently maintained at a temperature ranging from about 230 °C to about 300 °C.

[0070] Aspect 11 provides the method of Aspect 10, wherein the twin-screw extruder comprises a plurality of heating zones independently maintained at a temperature ranging from about 250 °C to about 275 °C.

[0071] Aspect 12 provides the method of any of Aspects 1-11, wherein a solvent used at (a), (b), or both comprises water.

[0072] Aspect 13 provides the method of any of Aspects 1-12, where a pH measured at any point during the method is greater than 6.5.

[0073] Aspect 14 provides the method of any of Aspects 1-12, where a pH measured at any point during the method is in a range of from about 6.5 to about 13.

[0074] Aspect 15 provides the method of any of Aspects 1-14, wherein a weightaverage molecular weight of the oligoamide is in a range of from about 450 g / mol to about 3500 g / mol.

[0075] Aspect 16 provides the method of Aspect 15, wherein the weight-average molecular weight of the oligoamide is in a range of from about 500 g / mol to about 2500 g / mol.

[0076] Aspect 17 provides the method of any of Aspects 1-16, wherein a dropping point of a grease composition including the oligoamide is greater than about 200 °C.

[0077] Aspect 18 provides the method of any of Aspects 1-17, wherein a dropping point of a grease composition including the oligoamide is greater than about 250 °C.

[0078] Aspect 19 provides a method for making an oligoamide comprising: a) contacting terephthalic acid (PTA) and hexamethylene diamine (HMD) in aqueous solution under conditions sufficient to at least partially convert the PTA and HMD to a first crude product comprising a salt; b) separating excess HMD from the first crude product of (a) and reacting the recovered oligomeric salt with stearic acid to produce a second crude product; and c) recovering oligoamide from the crude product of step (b).

[0079] Aspect 20 provides the method of any of Aspects 19-19, wherein the recovered oligomeric salt is reacted with steric acid in an extruder.

[0080] Aspect 21 provides the method of Aspect 20, wherein the extruder is a twin screw extruder.

[0081] Aspect 22 provides the method of Aspect 21, wherein the twin-screw extruder comprises a plurality of heating zones independently maintained at a temperature ranging from about 230 °C to about 300 °C.

[0082] Aspect 23 provides the method of Aspect 22, wherein the twin-screw extruder comprises a plurality of heating zones independently maintained at a temperature ranging from about 250 °C to about 275 °C.

[0083] Aspect 24 provides the method of any of Aspects 19-23, wherein a solvent used at (a), (b), or both comprises water.

[0084] Aspect 25 provides the method of any of Aspects 19-24, where a pH measured at any point during the method is greater than 6.5.

[0085] Aspect 26 provides the method of any of Aspects 19-25, where a pH measured at any point during the method is in a range of from about 6.5 to about 13.

[0086] Aspect 27 provides the method of any of Aspects 19-26, wherein a weightaverage molecular weight of the oligoamide is in a range of from about 450 g / mol to about 3500 g / mol.

[0087] Aspect 28 provides the method of Aspect 27, wherein the weight-average molecular weight of the oligoamide is in a range of from about 500 g / mol to about 2500 g / mol.

[0088] Aspect 29 provides the method of any of Aspects 19-28, wherein a dropping point of a grease composition including the oligoamide is greater than about 200 °C.

[0089] Aspect 30 provides the method of any of Aspects 19-29, wherein a dropping point of a grease composition including the oligoamide is greater than about 250 °C.

[0090] Aspect 31 provides a method for making an oligoamide grease thickening agent comprising: a) contacting an at least partially aromatic diacid and an aliphatic diamine under conditions sufficient to at least partially convert the at least partially aromatic dicarboxylic acid and the aliphatic diamine to a first crude product comprising a salt in the absence of added halogen-containing feed; b) separating excess aliphatic diamine from the first crude product of (a) and reacting the first crude product with a long-chain fatty acid to produce a second crude product; and c) recovering oligoamide from the crude product of step (b).

[0091] Aspect 32 provides the method of Aspect 31 wherein the dicarboxylic acid is selected from terephthalic acid, isophthalic acid and phthalic acid.

[0092] Aspect 33 provides the method of Aspect 32 wherein the dicarboxylic acid is terephthalic acid.

[0093] Aspect 34 provides the method of any of Aspects 31-33 wherein the long- chain fatty acid is a Cs to C40 fatty acid.

[0094] Aspect 35 provides the method of Aspect 34 wherein the long-chain fatty acid is a C12 to C24 fatty acid.

[0095] Aspect 36 provides the method of Aspect 35 wherein the long-chain fatty acid has suitable properties for reacting with the oligomeric salt of Aspect 1 to form grease thickening agent.

[0096] Aspect 37 provides the method of Aspect 36 wherein the long-chain fatty acid is characterized by properties including melting point, hardness, solubility and oxidation stability for use as a grease thickening agent component.

[0097] Aspect 38 provides the method of any of Aspects 31-37, wherein the recovered oligomeric salt is reacted with a long-chain fatty acid in an extruder.

[0098] Aspect 39 provides the method of Aspect 38, wherein the extruder is a twin screw extruder.

[0099] Aspect 40 provides the method of Aspect 39, wherein the twin-screw extruder comprises a plurality of heating zones independently maintained at a temperature ranging from about 230 °C to about 300 °C.

[0100] Aspect 41 provides the method of Aspect 40, wherein the twin-screw extruder comprises a plurality of heating zones independently maintained at a temperature ranging from about 250 °C to about 275 °C.

[0101] Aspect 42 provides the method of any of Aspects 31-41, wherein a solvent used at (a), (b), or both comprises water.

[0102] Aspect 43 provides the method of any of Aspects 31-42, where a pH measured at any point during the method is greater than 6.5.

[0103] Aspect 44 provides the method of any of Aspects 31-43, where a pH measured at any point during the method is in a range of from about 6.5 to about 13.

[0104] Aspect 45 provides the method of any of Aspects 31-44, wherein a weightaverage molecular weight of the oligoamide grease thickening agent is in a range of from about 450 g / mol to about 3500 g / mol.

[0105] Aspect 46 provides the method of Aspect 45, wherein the weight-average molecular weight of the oligoamide grease thickening agent is in a range of from about 500 g / mol to about 2500 g / mol.

[0106] Aspect 47 provides the method of any of Aspects 31-46, wherein a dropping point of a grease composition including the oligoamide grease thickening agent is greater than about 200 °C.

[0107] Aspect 48 provides the method of any of Aspects 31-48, wherein a dropping point of a grease composition including the oligoamide grease thickening agent is greater than about 250 °C.

[0108] Aspect 49 provides a method of making an oligoamide grease thickening agent; the method comprising the steps of: contacting an aromatic dicarboxylic acid and a diamine in a first reaction zone; maintaining the conditions in the first reaction zone to obtain a first reaction product; recovering the first reaction product from the first reaction zone; contacting the first reaction product from with a long-chain fatty acid; maintaining the conditions in the second reaction zone to obtain a second reaction product; and recovering the second reaction product from the second reaction zone; wherein, the second reaction product is characterized as the oligoamide grease thickening agent including at least two para-substituted aromatic moieties, have a molecular weight in a range of from 450 g / mol to 3500 g / mol, and at least four amide bonds.

[0109] Aspect 50 provides the method of Aspect 49, wherein the aromatic dicarboxylic acid is terephthalic acid.

[0110] Aspect 51 provides the method of any of Aspects 49 or 50, wherein the diamine is a linear C4-C12 diamine.

[0111] Aspect 52 provides the method of any of Aspects 49-51, wherein the diamine is selected from the group consisting of pentamethylenediamine and hexamethylenediamine.

[0112] Aspect 53 provides the method of any of Aspects 49-52, wherein the long- chain fatty acid is a C10-C30 monoacid.

[0113] Aspect 54 provides the method of any of Aspects 49-53, wherein the long- chain fatty acid is stearic acid.

[0114] Aspect 55 provides the method of any of Aspects 49-54, wherein a solvent used at any point in the method comprises water.

[0115] Aspect 56 provides the method of any of Aspects 49-55, wherein the aromatic dicarboxylic acid is terephthalic acid, the diamine is hexamethylenediamine and the long- chain fatty acid is stearic acid.

[0116] Aspect 57 provides the method of any of Aspects 49-56, wherein the grease thickening agent has the structure according to Formula I:(MCA-DA-)(PCA-DA)y-PCA-(DA-PCA)y(-DA-MCA) (I), wherein at each occurrence PCA is independently a reacted polycarboxylate, at each occurrence MCA is independently a reacted monocarboxylate, at each occurrence DA is independently a reacted diamine, y is 0 or a non-zero integer, a weight-average molecular weight of the oligoamide grease thickening agent is in a range of from about 450 g / mol to about 3500 g / mol, and at least one cycloaliphatic moiety or aromatic moiety.

[0117] Aspect 58 provides the method of Aspect of Aspect 57, wherein the weightaverage molecular weight of the oligoamide grease thickening agent is in a range of from about 500 g / mol to about 2500 g / mol.

[0118] Aspect 59 provides the method of any of Aspects 57 or 58, wherein the oligoamide grease thickening agent has the structure according to Formula II:((MCA-DA-)(PCA-DA)y-)nPCA (II), wherein n is 2, and y is in a range of 2-4.

[0119] Aspect 60 provides the method of any of Aspects 57-59, wherein the oligoamide grease thickening agent has the structure according to Formula III:(MCA-DA)-PCA-(DA-MCA) (III).

[0120] Aspect 61 provides the method of any of Aspects 57-60, wherein at each occurrence PCA independently comprises 6 to 50 carbon atoms.

[0121] Aspect 62 provides the method of any of Aspects 57-61, wherein at each occurrence PCA independently comprises 6, 8, or 9 carbon atoms.

[0122] Aspect 63 provides the method of any of Aspects 57-62, wherein at each occurrence PCA has the same chemical structure.

[0123] Aspect 64 provides the method of any of Aspects 57-63, wherein at least two occurrences PCA have different chemical structures.

[0124] Aspect 65 provides the method of any of Aspects 57-64, wherein at each occurrence, PCA independently comprises a reacted adipic acid, a reacted purified terephthalic acid, a reacted isophthalic acid, a reacted phthalic anhydride, a reacted napthalenic acid, a reacted mellitic acid, a reacted mellitic anhydride, a reacted naphthalene tetracarboxylic anhydride, a reacted citric acid, a reacted ester, a reacted dianhydride, or a reacted ethylenediaminetetraacetic acid.

[0125] Aspect 66 provides the method of any of Aspects 57-65, wherein at each occurrence MCA independently comprises a reacted aliphatic monocarboxylate, a reacted alicyclic monocarboxylate, or a reacted aromatic monocarboxylate.

[0126] Aspect 67 provides the method of any of Aspects 57-66, wherein at each occurrence MCA has the same chemical structure.

[0127] Aspect 68 provides the method of any of Aspects 57-67, wherein at least two occurrences of MCA has a different chemical structure.

[0128] Aspect 69 provides the method of any of Aspects 57-68, wherein at each occurrence MCA comprises a reacted monocarboxylate, the monocarboxylate having the structure according to Formula (VI):wherein R3is a substituted or unsubstituted (Ci-C2o)hydrocarbyl and R7is chosen from -OH, -O', or substituted or unsubstituted -0-(Ci-C2o)hydrocarbyl.

[0129] Aspect 70 provides the method of Aspect 69, wherein at each occurrence the substituted or unsubstituted (Ci-C2o)hydrocarbyl is independently selected from a substituted or unsubstituted (Ci-C2o)alkyl, a substituted or unsubstituted (C3-C2o)cycloalkyl, a substituted or unsubstituted (C2-C2o)alkenyl, a substituted or unsubstituted (C2-C2o)alkynyl, a substituted or unsubstituted (Ci-C2o)acyl, a substituted or unsubstituted (C4-C2o)aryl, and a substituted or unsubstituted (C2-C2o)alkoxy.

[0130] Aspect 71 provides the method of any of Aspects 69 or 70, wherein at each occurrence MCA comprises a reacted monocarboxylate, the monocarboxylate having the structure according to:Formula (V):Formula (VI):Formula (VII):wherein R4is chosen from a bond and a substituted or unsubstituted (Ci- C2o)hydrocarbylene.

[0131] Aspect 72 provides the method of Aspect 71, wherein at each occurrence the substituted or unsubstituted (Ci-C2o)hydrocarbylene is independently selected from a substituted or unsubstituted (Ci-C2o)alkylene, a substituted or unsubstituted (C3- C2o)cycloalkylene, a substituted or unsubstituted (C2-C2o)alkenylene, a substituted or unsubstituted (C2-C2o)alkynylene, a substituted or unsubstituted (Ci-C2o)acylene, a substituted or unsubstituted (C4-C2o)arylene, and a substituted or unsubstituted -O-(CH2)n- (n = 2-20).

[0132] Aspect 73 provides the method of any of Aspects 57-72, wherein at each occurrence the MCA is independently selected from a reacted ester, a reacted anhydride, a reacted benzoic acid, a reacted cyclohexanecarboxylic acid, and a reacted steric acid.

[0133] Aspect 74 provides the method of any of Aspects 57-73, wherein at each occurrence DA has the same chemical structure.

[0134] Aspect 75 provides the method of any of Aspects 57-74, wherein at least two occurrences of DA have a different chemical structure.

[0135] Aspect 76 provides the method of any of Aspects 57-75, wherein at each occurrence, the DA is a reacted diamine, the diamine independently having the structure according to Formula (VII):R5H2NXNH2(Xwherein R5is a substituted or unsubstituted (Ci-C2o)alkylene, substituted or unsubstituted (C5-C2o)cycloalkylene, or substituted or unsubstituted (C4-C2o)aryl.

[0136] Aspect 77 provides the method of Aspect 76, wherein at each occurrence DA is a reacted diamine independently selected from a reacted hexamethylenediamine, a reacted propanediamine, a reacted butanediamine, a reacted pentanediamine, a reacted phenylenediamine, a reacted cyclohexandiamine, or a reacted nonanediamine.

[0137] Aspect 78 provides the method of any of Aspects 57-77, wherein at each occurrence DA is a reacted diamine independently selected from a reacted hexamethylenediamine, a reacted propanediamine, a reacted butanediamine, or a reacted pentanediamine.

[0138] Aspect 79 provides the method of any of Aspects 57-78, wherein at each occurrence DA is a reacted hexamethylenediamine.

[0139] Aspect 80 provides the method of any of Aspects 49-79, wherein a dropping point of a grease composition including the oligoamide grease thickening agent is greater than about 200 °C.

[0140] Aspect 81 provides the method of any of Aspects 49-80, wherein a dropping point of a grease composition including the oligoamide grease thickening agent is greater than about 250 °C.

[0141] Aspect 82 provides the method of any of Aspects 49-81, wherein when the at least one aromatic moiety is internally disposed it is di-substituted in a para position and when the at least one cycloaliphatic moiety is internally disposed it is disubstituted and symmetrical about an axis passing through both substituents.

[0142] Aspect 83 provides the method of any of Aspects 49-82, wherein the structure according for Formula I, includes at least two aromatic moi eties and at least one aromatic moiety is a mono-substituted end group of Formula I.

[0143] Aspect 84 provides the method of any of Aspects 49-83, wherein the conditions in the first reaction zone, the second reaction zone, or both comprise a temperature, a reaction time, or both.

[0144] Aspect 85 provides the method of Aspect 84, wherein the temperature is increased during the method.

[0145] Aspect 86 provides the method of Aspect 85, wherein the temperature increases from about 25 °C to about 250 °C.

[0146] Aspect 87 provides the method of any of Aspects 85 or 86, wherein the temperature increases from about 30 °C to about 200 °C.

[0147] Aspect 88 provides the method of any of Aspects 49-87, wherein the reaction time ranges from about 30 minutes to about 15 hours.

[0148] Aspect 89 provides the method of any of Aspects 49-88, wherein the reaction time ranges from about 30 minutes to about 12 hours.

[0149] Aspect 90 provides the method of any of Aspects 49-89, wherein the reaction zones are present in a twin screw extruder.

[0150] Aspect 91provides a grease composition; the composition comprising: an oligoamide grease thickening agent prepared by the method of any of Aspects 49- 90 and a base oil; wherein the base oil is selected from the group consisting of a vegetable oil, a synthetic oil, an ester, mineral oil, alkylated naphthalene and combinations thereof; and the amount of the oligoamide grease thickening agent is about 5-25 wt% of the total composition; and wherein the grease composition is substantially free of lithium, polyurea, or both; has the dropping point in the range of from about 280°C to about 330°C; has Po value in the range of from about 220 to about 290, Peo in the range of from about 230 to about 300, and Pioooo value in the range of from about 290 to about 330.

[0151] Aspect 92 provides the grease composition of Aspect 91, wherein the oligoamide grease thickening agent is in a range of from about 8-20 wt% of the total composition.

[0152] Aspect 93 provides the grease composition of any of Aspects 91 or 92, wherein the oligoamide grease thickening agent is in a range of from about 10-18 wt% of the total composition.

[0153] Aspect 94 provides the grease composition of any of Aspects 91-93, wherein the grease composition comprises lithium, polyurea, or a mixture thereof.

[0154] Aspect 95 provides the grease composition of Aspect 94, wherein the lithium, polyurea, or mixture thereof is less than 1 wt% of the grease composition.

Claims

CLAIMSWhat is claimed is:

1. A method for making an oligoamide comprising: a) contacting an at least partially aromatic diacid and an aliphatic diamine under conditions sufficient to at least partially convert the at least partially aromatic diacid and the aliphatic diamine to a first crude product comprising a salt; b) separating excess aliphatic diamine from the first crude product of (a) and reacting the recovered salt with a long-chain fatty acid to produce a second crude product; and c) recovering oligoamide from the crude product of step (b).

2. The method of claim 1, where a pH measured at any point during the method is in a range of from about 6.5 to about 13.

3. The method of claim 1, wherein the recovered salt is reacted with a long-chain fatty acid in a twin-screw extruder comprising a plurality of heating zones independently maintained at a temperature ranging from about 230 °C to about 300 °C.

4. A method for making an oligoamide grease thickening agent comprising: a) contacting an at least partially aromatic diacid and an aliphatic diamine under conditions sufficient to at least partially convert the at least partially aromatic diacid and the aliphatic diamine to a first crude product comprising a salt in the absence of added halogencontaining feed; b) separating excess aliphatic diamine from the first crude product of (a) and reacting the recovered salt with a long-chain fatty acid under conditions sufficient to produce a second crude product; and c) recovering oligoamide from the crude product of step (b).

5. The method of claim 4, wherein the dicarboxylic acid is selected from terephthalic acid and isophthalic acid.

6. The method of claim 4, wherein the long-chain fatty acid is a Cs to C40 fatty acid.

7. The method of claim 6, wherein the long-chain fatty acid has suitable properties for reacting with the salt of claim 1 to form the oligoamide grease thickening agent.

8. The method of claim 4, wherein the recovered salt is reacted with a long-chain fatty acid in an extruder.

9. The method of claim 8, wherein the extruder is a twin-screw extruder.

10. The method of claim 9, wherein the twin-screw extruder comprises a plurality of heating zones independently maintained at a temperature ranging from about 230 °C to about 300 °C.

11. The method of claim 4, wherein a solvent used at (a), (b), or both comprises water.

12. The method of claim 4, where a pH measured at any point during the method is greater than 6.5.

13. A method of making an oligoamide grease thickening agent; the method comprising the steps of: contacting an aromatic dicarboxylic acid and a diamine in a first reaction zone; maintaining the conditions in the first reaction zone to obtain a first reaction product; recovering the first reaction product from the first reaction zone; contacting the first reaction product with a long-chain fatty acid; maintaining the conditions in the second reaction zone to obtain a second reaction product; and recovering the second reaction product from the second reaction zone; wherein, the second reaction product is characterized as the oligoamide grease thickening agent including at least two para-substituted aromatic moieties on average, have a molecular weight in a range of from 450 g / mol to 3500 g / mol, and at least four amide bonds.

14. The method of claim 13, wherein the aromatic dicarboxylic acid is terephthalic acid.

15. The method of claim 13, wherein the diamine is a linear C4-C12 diamine.

16. The method of claim 13, wherein the diamine is selected from the group consisting of pentamethylenediamine and hexamethylenediamine.

17. The method of claim 13, wherein the long-chain fatty acid is a C10-C30 monoacid.

18. The method of claim 13, wherein the long-chain fatty acid is stearic acid.

19. The method of claim 13, wherein a solvent used at any point in the method comprises water.

20. The method of claim 13, wherein the aromatic dicarboxylic acid is terephthalic acid, the diamine is hexamethylenediamine and the long-chain fatty acid is stearic acid.