EP0537386B1

EP0537386B1 - Modified dispersant compositions

Info

Publication number: EP0537386B1
Application number: EP91309188A
Authority: EP
Inventors: Mark Rees; Helen Theresa Ryan; Roger Scattergood
Original assignee: Afton Chemical Ltd
Current assignee: Afton Chemical Ltd
Priority date: 1991-10-08
Filing date: 1991-10-08
Publication date: 1996-12-11
Anticipated expiration: 2011-10-08
Also published as: EP0537386A1; DE69123585D1; DE69123585T2

Description

This invention relates to novel modified ashless dispersants, to processes for their production, and to their use in liquid hydrocarbonaceous media. As used herein, the term "ashless" is used in the normal art-recognized sense of denoting that the composition is devoid of metals such as alkali or alkaline earth metals, zinc or other metals that tend to produce metal-containing residues. In this connection, phosphorus is not deemed a metal as the compositions of this invention do contain phosphorus.
A continuing problem in the art of lubrication is to provide lubricant compositions which satisfy the demands imposed upon them by the original equipment manufacturers. One such requirement is that the lubricant not contribute to premature deterioration of seals, clutch face plates or other parts made from fluoroelastomers. Unfortunately, and as is well known, basic nitrogen-containing dispersants such as succinimide dispersants commonly used in oils tend to exhibit a strong adverse effect upon fluoroelastomers, by causing them to lose their flexibility and tensile strength, to become embrittled, and in severe cases, to disintegrate. Contemporary test methods for evaluating fluoroelastomer compatibility of lubricants and functional fluids are the Volkswagen P.VW 3334 Elastomer Compatibility Test, the CCMC Oil-Elastomer Seal Test (CEC L-39-T-87), and the fluoroelastomer seal test in accordance with the TO-3 Caterpillar Specification.
Methods of post-treating various nitrogen-containing dispersants with various substances are well documented in the literature.
USP 4,940,552 relates to polyamine dispersants passivated toward fluorohydrocarbon compositions. The dispersants described comprise the reaction product of a Mannich polyamine dispersant with an amount of. maleic anhydride sufficient to reduce the reactivity with fluorohydrocarbons of the dispersant.
EP-A-454,380 describes a lubricating oil composition stated to be effective for preventing low temperature sludge formation and wear. The composition comprises a combination of a hydrocarbon-substituted succinimide and a Mannich condensation product.
In accordance with this invention, there is provided an oil soluble dispersant composition formable by reacting a basic nitrogen-containing ashless dispersant (i) with at least one dibasic acylating agent containing up to 12, preferably up to 8, more preferably up to 6, and most preferably 4, carbon atoms, and (ii) with at least one phosphorylating compound selected from phosphorous acid, hypophosphoric acid, metaphosphoric acid, pyrophosphoric acid, hypophosphorous acid, pyrophosphorous acid, phosphinous acid, tripolyphosphoric acid, tetrapolyphosphoric acid, trimetaphosphoric acid, PoCl₃, PCl₃ and PBr₃, said reactions (i) and (ii) being conducted concurrently or sequentially in any order such that the initial ashless dispersant is chemically modified via acylation in (i) and by phosphorylation in (ii). The phosphorus compound or compounds react with the basic nitrogen-containing ashless dispersant to introduce phosphorus moieties into the dispersant. It is preferred to conduct the phosphorylation in (ii) using at least one inorganic phosphorus acid, most preferably phosphorous acid, H₃PO₃, or any combination thereof.
The preferred acylating agents used in the reaction identified as (i) above are maleic anhydride, maleic acid, fumaric acid, malic acid or any combination of any two, any three or all four of these compounds.
Preferred embodiments of the invention include conducting reaction (i) prior to reaction (ii), conducting reaction (ii) prior to reaction (i) and conducting reactions (i) and (ii) concurrently.
Ashless dispersants utilized in the foregoing processing include hydrocarbyl succinimides, hydrocarbyl succinamides, mixed ester/amides or hydrocarbyl-substituted succinic acids, Mannich condensation products of hydrocarbyl-substituted phenols, formaldehyde and polyamines, and amine dispersants formed by reacting high molecular weight aliphatic or alicyclic halides with amines, such as polyalkylene polyamines. Mixtures of such dispersants can also be used.
Such basis nitrogen-containing ashless dispersants are well known lubricating oil additives, and methods for their preparation are extensively described in the patent literature.
The preferred ashless dispersants include hydrocarbyl succinimides in which the hydrocarbyl substituent is a hydrogenated or unhydrogenated polyolefin group and preferably a polyisobutene group having a number average molecular weight (as measured by gel permeation chromatography) of from 250 to 10,000, and more preferably from 500 to 5,000, and most preferably from 750 to 2,500. The ashless dispersant is most preferably an alkenyl succinimide.
Another embodiment of this invention is the provision of a dispersant prepared as above having the ability when formulated in a finished engine lubricating oil of satisfying the requirements of the ASTM sequence VE engine tests for API "SG" performance (see ASTM 315 H, part III Seq. VE), and the requirements of the Volkswagen P.VW 3334 Elastomer Compatibility Test and/or the requirements of the CCMC Oil-Elastomer Compatibility Test (CEC L-39-T-87) and/or the fluoroelastomer seal test in accordance with the TO-3 Caterpillar Specification.
Other embodiments of this invention involve the provision of additive concentrates, for lubricating oil for example, comprising an effective amount of an improved dispersant composition of this invention and a lubricating oil or functional fluid composition comprising a major proportion of an oil of lubricating viscosity and a minor dispersant amount of the improved dispersant composition.
Still further embodiments of this invention are processes for producing the improved dispersant compositions of this invention. One such embodiment comprises reacting a basic nitrogen-containing ashless dispersant with a least one dibasic acylating agent containing up to 12, preferably up to 8, more preferably up to 6, and most preferably 4, carbon atoms, and with at least one phosphorus compound as described above, said reactions being conducted concurrently or sequentially in any order such that the initial ashless dispersant is chemically modified via acylation and by phosphorylation. Another such embodiment of this invention comprises reacting a phosphorylated basic nitrogen-containing ashless dispersant with at least one dibasic acylating agent containing up to 12, preferably up to 8, more preferably up to 6, and more preferably 4, carbon atoms, such that the resultant phosphorylated ashless dispersant is chemically modified via acylation. Another such embodiment of this invention comprises reacting an ashless dispersant which has been acylated with a least one dibasic acylating agent containing up to 12, preferably up to 8, more preferably up to 6, and most preferably 4, carbon atoms, with at least one phosphorus compound as described above, such that the resultant acylated ashless dispersant is chemically modified via phosphorylation.
These and other embodiments and features of this invention will be apparent from the ensuing description and appended claims.

Basic Nitrogen-Containing Ashless Dispersants

As noted above, the process of this invention can be applied to any basic nitrogen-containing ashless dispersant susceptible to acylation and phosphorylation. Thus the process can be applied to any of the basic nitrogen-containing dispersants referred to hereinabove.
The preferred basic nitrogen-containing dispersants utilized in the practice of this invention are the hydrocarbyl succinimides. As used herein the term "succinimide" is meant to encompass the completed reaction product from reaction between a hydrocarbyl substituted succinic acylating agent and a polyamine and is intended to encompass compounds wherein the product may have amide, amidine, and/or salt linkages in addition to the imide linkage of the type that results from the reaction of a primary amino group and an anhydride moiety.
Of the succinimides, those having an average of at least 3 nitrogen atoms per molecule are preferred. Most preferred are those formed by use as one of the reactants of at least one aliphatic hydrocarbyl substituted succinic acylating agent in which the hydrocarbyl substituent contains an average of at least 40 carbon atoms.
Preferably, the dispersant is a succinimide dispersant formed from an alkyl or alkenyl succinic acylating agent having an average of at least 40 carbon atoms in the alkyl or alkenyl group and an alkylene polyamine mixture having an average of at least 3 nitrogen atoms per molecule. More preferably, the dispersant is a succinimide dispersant formed from a polyisobutenyl succinic acylating agent derived from polyisobutene having a number average molecular weight in the range of 500 to 10,000 and an ethylene polyamine mixture including cyclic and acyclic structures, said mixture having an average overall composition approximating to a mixture in the range of from triethylene tetramine to pentaethylene hexamine. Another preferred category of such acylating agents is comprised of at least one hydrocarbyl substituted succinic acylating agent in which the substituent is principally alkyl, alkenyl, or polyethylenically unsaturated alkenyl, or any combination thereof and wherein such substituent has an average of from 50 to 5000 carbon atoms. Particularly preferred for use as the acylating agent is (a) at least one polyisobutenyl substituted succinic acid or (b) at least one polyisobutenyl substituted succinic anhydride or (c) a combination of at least one polyisobutenyl substituted succinic acid and at least one polyisobutenyl substituted succinic anhydride in which the polyisobutenyl substituent in (a), (b) or (c) is derived from polyisobutene having a number average molecular weight in the range of 700 to 5,000.
As is well known, the substituted succinic acylating agents are those which can be characterized by the presence within their structure of two groups or moieties. The first group or moiety is a substituent group derived from a polyalkene. The polyalkene from which the substituted groups are derived is characterized by an Mn (number average molecular weight) value of typically from 500 to 10,000, and preferably in the range of from 700 to 5,000.
The second group or moiety is the succinic group, a group characterized by the structure
wherein X and X' are the same or different provided at least one of X and X' is such that the substituted succinic acylating agent can function as a carboxylic acylating agent. In other words, at least one of X and X' must be such that the substituted acylating agent can esterify alcohols, form amides or amine salts with ammonia or amines, form metal salts with reactive metals or basically reacting metal compounds, and otherwise functions as a conventional carboxylic acid acylating agent. Transesterification and transamidation reactions are considered, for purposes of this invention, as conventional acylation reactions.
Thus, X and/or X' is usually -OH, -O-hydrocarbyl; -O^-M⁺ where M⁺ represents one equivalent of a metal, ammonium or amine cation, -NH₂, -Cl, -Br, and together, X and X' can be -O- so as to form the anhydride.
Any of a variety of known procedures can be used to produce the substituted succinic acylating agents.
One procedure for preparing the substituted acylating agents is illustrated, in part, by the two-step procedure described in U.S. Pat. No. 3,219,666.
Another procedure for preparing substituted succinic acid acylating agents utilizes a process described in U.S. Pat. No. 3,912,764 and U.K. Pat. No. 1,440,219.
Other known processes for preparing the substituted succinic acylating agents include the one-step process described in U.S. Pat. Nos. 3,215,707 and 3,231,587.
Further details concerning procedures for producing the substituted acylating agents have been extensively described in the patent literature, such as for example in U.S. Pat. No. 4,234,435. Thus, further amplification of such procedures herein is deemed unnecessary.
The other principal reactant utilized in forming the succinimides which preferably are used in the process of this invention is one or a mixture of polyamines which preferably has at least one primary amino group in the molecule and which additionally contains an average of at least two other amino nitrogen atoms in the molecule. For best results, the polyamines should contain at least two primary amino groups in the molecule.
One preferred type of polyamines is comprised of alkylene polyamines such as those represented by the formula

H₂N(CH₂)_n(NH(CH₂)_n)_mNH₂

wherein n is 2 to about 10 (preferably 2 to 4, more preferably 2 to 3, and most preferably 2) and m is 0 to 10, (preferably 1 to 6). Particularly useful commercially-available mixtures of polyethylene polyamines are those having an overall average approximate composition falling in the range of triethylene tetramine to pentaethylene hexamine. Commercially available mixtures of polyethylene polyamines often contain minor amounts of cyclic species such as aminoalkyl-substituted piperazines and the like.
In principle, therefore, any polyamine having at least one primary amino group and an average of at least three amino nitrogen atoms in the molecule can be used in forming the succinimide utilized in the practice of this invention. As noted above, product mixtures known in the trade as "triethylene tetramine", "tetraethylene pentamine", and "pentaethylene hexamine" are most preferred.
In forming the initial preferred succinimide used in the practice of this invention mole ratios of the hydrocarbyl substituted succinic acylating agent to polyamine reactant ranges from 1:1 to 4:1, and preferably from 1.5:1 to 3:1.

Dibasic Acylating Agent

A wide variety of dibasic acylating agents can be reacted with the basic nitrogen-containing ashless dispersant (e.g., succinimide, Mannich reaction product, succinic acid ester-amide, etc.) in the reaction of (i) above. The principal requirement is that such acylating agent contain at most 12 carbon atoms in the molecule, preferably up to 8 carbon atoms in the molecule, and more preferably up to 6 carbon atoms in the molecule. The most preferred acylating agents for use in reaction (i) contain 4 carbon atoms in the molecule. Thus use can be made of dibasic acids and anhydrides, esters and acyl halides thereof which contain a total of up to 12 carbon atoms in the molecule (excluding carbon atoms of an estemfying alcohol). Among such compounds are azelaic acid, adipic acid, succinic acid, lower alkyl-substituted succinic acid, succinic anhydride, lower alkyl-substituted succinic anhydride, glutaric acid, pimelic acid, sebacic acid, and like dibasic acids, anhydrides, acyl halides, and esters which contain (excluding carbon atoms of esterifying alcohols) up to 12 carbon atoms in the molecule. Preferred are maleic acid, maleic anhydride, fumaric acid and malic acid or any combination thereof. Most preferred is maleic anhydride.

Phosphorus Compounds

The other reactant(s) with which the basic nitrogen-containing dispersant is reacted either before, during or subsequent to reaction with the above dibasic acylating agent is a phosphorus compound or mixture of phosphorus compounds capable of introducing phosphorus-containing species into the ashless dispersant undergoing such reaction.
The following compounds are used phosphorous acid (H₃PO_3, sometimes depicted as H₂(HPO₃), and sometimes called orthophosphorous acid or phosphonic acid), hypophosphoric acid (H₄P₂O₆), metaphosphoric acid (HPO₃), pyrophosphoric acid (H₄P₂O₇), hypophosphorous acid (H₃PO₂, sometimes called phosphinic acid), pyrophosphorous acid (H₄P₂O₅, sometimes called pyrophosphonic acid), phosphinous acid (H₃PO), tripolyphosphoric acid (H₅P₃O₁₀), tetrapolyphosphoric acid (H₆P₄O₁₃) and trimetaphosphoric acid (H₃P₃O₉). Also used, though less preferred, are the inorganic phosphorus halide compounds such as PCl₃, PBr₃, and POCL₃. The preferred phosphorus reagent is phosphorous acid, H₃PO₃).

Reaction Conditions

In conducting the foregoing reactions, any temperature at which the desired reaction(s) occur at a satisfactory reaction rate can be used. Ordinarily, the acylation reaction between the basic nitrogen-containing dispersant (phosphorylated or non-phosphorylated) and the dibasic acylating agent is conducted at temperatures in the range of 80 to 200°C, more preferably 140 to 180°C. The phosphorylation reaction is likewise normally performed at temperatures within either of the foregoing ranges. However, departures from these ranges can be made whenever deemed necessary or desirable. These reactions may be conducted in the presence or absence of an ancillary diluent or liquid reaction medium, such as a mineral lubricating oil solvent. If the reaction is conducted in the absence of an ancillary solvent of this type, such is usually added to the reaction product on completion of the reaction. In this way the final product is in the form of a convenient solution in lubricating oil and thus is compatible with a lubricating oil base stock. Suitable solvent oils include lubricating oils having a viscosity (ASTM D 445) of 2 to 40, preferably 3 to 12 centistokes (cSt) at 100°C, with the primarily paraffinic mineral oils such as Solvent 100 Neutral being particularly preferred. Other types of lubricating oil base stocks can be used, such as synthetic lubricants including polyesters, poly-α-olefins, and the like. Blends of mineral oil and synthetic lubricating oils are also suitable for various applications in accordance with this invention.
The proportions of the reactants will to some extent be dependent on the nature of the basic-nitrogen containing dispersant being utilized, principally the content of basic nitrogen therein. Thus optimal proportions may, in some cases, be best defined by performing a few pilot experiments. Generally speaking, however, the dibasic acylating agent is employed in amounts ranging from 0.01 to 0.5 moles per average equivalent of nitrogen in the initial ashless dispersant(s), with the proviso that the resultant product contains at least 0.05 equivalent of basic nitrogen. Preferably the amount of dibasic acylating agent employed ranges from about 0.02 to 0.3 moles per average equivalent of nitrogen in the initial ashless dispersant with the proviso that the resultant product contains at least 0.1 equivalent of basic nitrogen. In the case of use of a succinimide as the initial ashless dispersant, it is preferred to utilize an amount of the dibasic acylating agent such that the total mole ratio o (a) dibasic acylating agent plus (b) the aliphatic hydrocarby substituted succinic acylating agent used in forming the initial succinimide falls in the range of from 1.5 to 3.5 moles of (a) and (b) per mole of polyamine, more preferably 1.6 to 2.8 moles of (a) and (b) per mole of polyamine, and most preferably 1.6 to 2.2 moles of (a) and (b) per mole of polyamine. Here again, departures from such proportions may be utilized if found efficacious in any given situation.
In the case of the phosphorus reactant, the amounts used should be sufficient to introduce up to about 5%, and preferably from 0.05 to 2.5% of phosphorus (expressed as weight % of elemental phosphorus) into the overall final co-reacted dispersant.
It will be understood of course that in any given case the amount of dibasic acylating agent and phosphorus compound used should be sufficient to provide a product having both satisfactory fluoroelastomer compatibility and adequate dispersancy performance.

Modified Processing

As noted above, the dispersants of this invention are formed by subjecting a basic nitrogen-containing ashless dispersant to two reactions, namely, acylation with at least one dibasic acylating agent and phosphorylation with at least one phosphorylation reagent. Ordinarily these reactions will be conducted either concurrently or in sequence. It is, of course, not necessary that both reactions be conducted in the same plant or at periods of time proximate to each other. For example, in one embodiment of this invention, a phosphorylated basic nitrogen-containing ashless dispersant from one manufacturer need only be subjected to acylation with a dibasic acylating agent of the type described hereinabove in order to produce a novel phosphorylated-acylated ashless dispersant of this invention. Likewise, one may procure a suitable acylated basic nitrogen-containing ashless dispersant from a given supplier (i.e., a basic nitrogen-containing ashless dispersant which has been subjected to acylation with a dibasic acylating agent of the type described hereinabove) and subject the same to phosphorylation in order to produce a novel acylated-phosphorylated ashless dispersant of this invention. In short, the novel products of this invention can be produced in accordance with this invention by two or more distinct and separate parties, if desired.

Further Treatments

Although ordinarily unnecessary, the acylated, phosphorylated ashless dispersants of this invention can be reacted with one or more additional treating agents, either before, during or after either or both of the above-referred-to acylating and phosphorylation reactions, Treating agents used for this purpose include, for example, carbon disulphide, hydrogen sulphide, sulphur, sulphur chloride, alkenyl cyanides, mono-, tri-, tetra-, etc. carboxylic acid acylating agents, aldehyde, ketones, urea, thiourea, guanidine, dicyanodiamide, hydrocarbyl thiocyanates, hydrocarbyl isocyanates, hydrocarbyl isothiocyanates, epoxides, episulphides, formaldehyde or formaldehyde producing compounds plus phenols, sulphur plus phenols, and many others.
Since treating processes involving numerous treating reagents are known as regards treatment of various ashless dispersants, further details concernina such technology are readily available in the literature.

Uses

The novel compositions of this invention can be used as ashless dispersants in a wide variety of oleaginous fluids and as detergents or deposit reducers in hydrocarbonaceous fuels such as gasoline, diesel fuel, kerosene, burner fuel, gas oil, jet fuel, turbine fuel, and the like. They can be used in lubricating oil and functional fluid compositions, such as automotive crankcase lubricating oils, automatic transmission fluids, gear oils, hydraulic oils, cutting oils, etc. The lubricant may be a mineral oil, a synthetic oil, a natural oil such as a vegetable oil, or a mixture thereof,
Synthetic oils include both hydrocarbon synthetic oils and synthetic esters. Useful synthetic hydrocarbon oils include liquid α-olefin polymers of appropriate viscosity. Especially useful are hydrogenated or unhydrogenated liquid oligomers of C₆-C₁₆ α-olefins, such as hydrogenated or unhydrogenated α-decene trimer. Alkyl benzenes of appropriate viscosity can also be used. Useful synthetic esters include the esters of monocarboxylic and polycarboxylic acids with monohydroxy alcohols and polyols. Complex esters made from mixtures of mono- and di-carboxylic acids and mono and/or polyhydric alkanols can also be used.
Typical natural oils that may be used include castor oil, olive oil, peanut oil, rapeseed oil, corn oil, sesame oil, cottonseed oil, soybean oil, sunflower oil, safflower oil, hemp oil, linseed oil, tung oil, oiticica oil, jojoba oil, and the like. Such oils may be partially or fully hydrogenated, if desired.
Viscosity index improvers may be included in the mineral, synthetic and natural oils (or any blends thereof) in order to achieve the viscosity properties deemed necessary or desirable.
The finished lubricating oil compositions and additive concentrates of this invention containing the present ashless dispersant systems will usually also contain other well-known additives in order to partake of their special properties. Among the numerous additives which can be employed in the lubricants and functional fluids and additive concentrates of this invention are those of the types described hereinafter.
The lubricants and functional fluids of this invention are of particular utility in applications wherein the oil of lubricating viscosity comes in contact with fluoroelastomers. In such applications, the compatibility of the lubricant or functional fluid of this invention so utilized, is significantly enhanced as compared to the corresponding lubricant or functional fluid containing the corresponding untreated basic nitrogen-containing ashless dispersant.
The concentrations of the ashless dispersants of this invention in oleaginous fluids will generally fall in the range of up to about 10 weight percent, for example 1 to 9 weight percent. When used in fuel compositions, amounts of up to about 5 weight percent are typical.
The following examples, in which all parts and percentages are by weight, illustrate, but do not limit, and should not be construed as limiting, the practice of this invention.

EXAMPLE 1

In a first stage reaction, polyisobutenylsuccinic anhydride (PIBSA) formed from polyisobutylene (number average molecular weight = 1300) and tetraethylene pentamine (TEPA) in a mole ratio of 1.8:1 are reacted at 165-170°C for 4 hours. In a second stage reaction, maleic anhydride (MA) is added to the first stage reaction product in amount equivalent to 0.35 mole per mole of TEPA used in the first stage and the resultant mixture is heated at 165-170°C for 1.5 hours after which oil is added. In a third stage reaction, phosphorous acid (H₃PO₃) is added to the second stage reaction mixture at a temperature of 105°C in an amount corresponding to 1.15 moles per mole of TEPA initially employed. The mixture is stirred at 105°C for 1.5 hours. Then the reaction mixture is heated to 120°C and water formed in the third stage reaction is removed by applying a vacuum of 40 mm for one hour. The resulting succinimide is both acylated and phosphorylated, and in a typical experiment had a nitrogen content of 1.79%, and a phosphorus content of 1.0%.

EXAMPLE 2

The procedure of Example 1 is repeated except that the amount of phosphorous acid is increased to 2.0 moles per mole of TEPA initially used. The final phosphorus- and nitrogen-containing product is diluted to 1.7% nitrogen content with 100 solvent neutral mineral oil.

EXAMPLE 3

Repetition of Example 1 wherein the amount of phosphorous acid is still further increased to 3.0 moles per mole of TEPA initially used yields a concentrate (diluted as in Example 1) having a phosphorus content above 2%.

EXAMPLE 4

Example 1 is repeated but using a 2.05:1 mole ratio of PIBSA to TEPA in the first stage. The phosphorus- and nitrogen-containing product is diluted as in Example 1 to a nitrogen content of 1.7%.

EXAMPLE 5

The procedure of Example 1 is repeated except that the reaction with phosphorous acid is conducted before the reaction with maleic anhydride and the amount of phosphorus acid used corresponds to 1.15 moles per mole of TEPA used in the first stage reaction. The final phosphorus- and nitrogen-containing product is diluted as in Example 1.

EXAMPLE 6

Example 5 is repeated except that the maleic anhydride and the phosphorous acid are concurrently reacted with the succinimide formed in the first stage reaction.

EXAMPLE 7

In the first stage reaction, polyisobutenylsuccinic anhydride (PIBSA) formed from polyisobutylene (number average molecular weight = 1300) and triethylene tetramine (TETA) in a mole ratio of 2:1 are reacted at 165-170°C for 4 hours and then mineral oil added. In a second stage reaction, maleic anhydride (MA) is added to the first stage reaction product in an amount equivalent to 0.3 moles per mole of TETA used in the first stage and the resultant mixture is heated at 165-170°C for 1 1/2 hours. In a third stage reaction, phosphorous acid is added to the second stage reaction product in an amount equivalent to 0.5 mole per mole of TETA used in the first stage and the resultant mixture is heated at 150-155°C for 2 1/2 hours. The resultant product contains both nitrogen and phosphorus.

EXAMPLE 8

In the first stage reaction, polyisobutenylsuccinic anhydride (PIBSA) (number average molecular weight = 1300) and TETA are reacted in a mole ratio of 1.8:1. In a second stage, maleic anhydride is added to the first stage reaction product in an amount equivalent to 0.35 mole per mole of TETA used in the first stage and the resultant mixture is heated at 165-170°C for 1 1/2 hours after which mineral oil is added. In a third stage reaction, phosphorous acid is added to the second stage reaction product in an amount equivalent to 2.0 moles per mole of TETA used in the first stage and the resultant mixture is heated at 150-155°C for 3 hours. The product so formed contains both nitrogen and phosphorus.

EXAMPLE 9

In the first stage reaction, polyisobutenylsuccinic anhydride (PIBSA) (number average molecular weight = 1300) and TEPA are reacted in a mole ratio of 1.8:1. In a second stage, maleic anhydride is added in an amount equivalent to 0.35 mol per mole of TEPA. The temperature is then adjusted to 100°C and phosphoryl chloride (POCl₃) is added in an amount equivalent to 1 mole per mole of TEPA. The resultant mixture is held at about 100°C for 2 hours. The temperature is then raised to 125°C and the mixture is stripped for 1 hour. In a typical run conducted in this manner, the resultant product contains 1.75% nitrogen and 0.64% phosphorus.
In order to determine the compatibility of typical succinimide dispersants of this invention with fluoroelastomers, tests were conducted using a typical crankcase lubricating oil formulation. The base oil contained, in addition to the succinimide dispersant, conventional amounts of overbased sulphonate, zinc dialkyl dithiophosphate, antioxidant, viscosity index improver, rust inhibitor, and antifoam agent to provide an SAE 15W/40 crankcase lubricant. In one case the dispersant was prepared as in Example 1 and in another case the dispersant was prepared as in Example 9. In both cases the succinimide dispersant was employed in an amount to provide a nitrogen content of 0.10% by weight.

The resultant finished lubricating oils were subjected to the Volkswagen P.VW 3334 Elastomer Compatibility Test. The results wherein VITON AK6 fluoroelastomer was used are summarized in Table 1.

Table 1 -

Results of Fluoroelastomer Seal Tests
Succinimide Used	Change in Elongation to Break Compared to Fresh Seal, %	Change in Tensile Strength Compared to Fresh Seal, %	Cracking Observed
Example 1	-19	-22	None
Example 9	-17	-28	None

In contrast, a corresponding untreated succinimide gives results in the above test in the order of -45% elongation change, -58% tensile strength change and it exhibits cracking.
Another feature of this invention is that the combined acylating and phosphorylation reactions, whether run serially in either order or concurrently, can yield products having lower viscosities and consequent improved handleability as compared to corresponding products formed using acylation only. For example a product formed by reacting PIBSA with TEPA and thereafter reacting the succinimide with maleic anhydride (MA) (mole ratios of PIBSA : TEPA : MA = 2.05 : 1 : 1 (1.8% nitrogen) has a viscosity of 4500 cSt at 100°C. But a product of this invention formed from PIBSA, TEPA and MA (mole ratio: 1.8 : 1 : 0.35 respectively) and a phosphorus content of 1.0% (1.8% nitrogen) has a viscosity at l00°C of approximately 1100 cSt.
It will thus be seen that highly effective crankcase lubricant formulations can be formed utilizing the dispersant compositions of this invention.
Additive concentrates of this invention generally contain 10 to 95 weight percent of one or more ashless dispersants of this invention, 0 to 90 weight percent liquid diluent and 0 to 90 weight percent of other additives commonly employed in lubricants and functional fluids.
The dispersants utilized according to the invention can be incorporated in a wide variety of lubricants. They can be used in lubricating oil compositions, such as automotive crankcase lubricating oils, automatic transmission fluids, or gear oils in effective amounts to provide active ingredient concentrations in finished formulations generally within the range of 0.5 to 10 weight percent, for example, 1 to 9 weight percent, preferably 2 to 8 weight percent, of the total composition. Conventionally, the dispersants are admixed with the lubricating oils as dispersant solution concentrates which usually contain up to about 50 weight percent of the active ingredient additive compound dissolved in mineral oil, preferably a mineral oil having an ASTM D-445 viscosity of 2 to 40, preferably 3 to 12 centistokes at 100°C. The lubricating oil not only can be hydrocarbon oils of lubricating viscosity derived from petroleum but also can be natural oils of suitable viscosities such as rapeseed oil, etc., and synthetic lubricating oils such as hydrogenated polyolefin oils; poly-α-olefins (e.g., hydrogenated or unhydrogenated α-olefin oligomers such as hydrogenated poly-1-decene); alkyl esters of dicarboxylic acids; complex esters of dicarboxylic acid, polyglycol and alcohol; alkyl esters of carbonic or phosphoric acids; polysilicones; fluorohydrocarbon oils; and mixtures of lubricating oils and synthetic oils in any proportion. The term "lubricating oil" for this disclosure includes all the foregoing. The useful dispersant may be conveniently dispersed as a concentrate of 10 to 80 weight percent of mineral oil, e.g., Solvent 100 Neutral oil with or without other additives being present and such concentrates are a further embodiment of this invention.
Other additives which may be included in the lubricants, functional fluids and additive concentrates of this invention include such substances as zinc dialkyl (C₃-C₁₀), dicycloalkyl (C₅-C₂₀), and/or diaryl (C₆-C₂₀) dithiophosphate wear inhibitors, generally present in amounts of about 0.5 to 5 weight percent. Useful detergents include the oil-soluble normal basic or overbased metal, e.g., calcium, magnesium, barium, etc., salts of petroleum naphthenic acids, petroleum sulfonic acids, alkyl benzene sulfonic acids, oil-soluble fatty acids, alkyl salicylic acids, sulphurized or unsulphurized alkyl phenates, and hydrolysed or unhydrolysed phosphosulphurized polyolefins. Gasoline engine crankcase lubricants typically contain, for example, from 0.5 to 5 weight percent of one or more detergent additives. Diesel engine crankcase oils may contain substantially higher levels of detergent additives. Preferred detergents are the calcium and magnesium normal or overbased phenates, sulphurized phenates or sulfonates.
Pour point depressants which may be present in amounts of from 0.01 to 1 weight percent in the lubricant or functional fluid include wax alkylated aromatic hydrocarbons, olefin polymers and copolymers, and acrylate and methacrylate polymers and copolymers.
Viscosity index improvers, the concentrations of which may vary in the lubricants from 0.2 to 15 weight percent, (preferably from 0.5 to 5 weight percent) depending on the viscosity grade required, include hydrocarbon polymers grafted with, for example, nitrogen-containing monomers, olefin polymers such as polybutene, ethylene-propylene copolymers, hydrogenated polymers and copolymers and terpolymers of styrene with isoprene and/or butadiene, polymers of alkyl acrylates or alkyl methacrylates, copolymers of alkyl methacrylates or alkyl methacrylates with N-vinyl pyrrolidine or dimethylaminoalkyl methacrylate, post-grafted polymers of ethylene-propylene with an active monomer such as maleic anhydride which may be further reacted with an alcohol or an alkylene polyamine, styrene/maleic anhydride polymers post-treated with alcohols and amines, etc.
Antiwear activity can be provided by about 0.01 to 2 weight percent in the oil of the aforementioned metal dihydrocarbyl dithiophosphates and the corresponding precursor esters, phosphosulphurized pinenes, sulphurized olefins and hydrocarbons, sulphurized fatty esters and alkyl polysulphides. preferred are the zinc dihydrocarbyl dithiophosphates which are salts of dihydrocarbyl esters of dithiophosphoric acids.
Other additives include effective amounts of friction modifiers or fuel economy additives such as the alkyl phosphonates as disclosed in U.S. 4,356,097, aliphatic hydrocarbyl substituted succinimides as disclosed in EPO 0020037, dimer acid esters, as disclosed in U.S. 4,105,571, oleamide, etc., which are present in the oil in amounts of 0.1 to 5 weight percent. Glycerol oleates are another example of fuel economy additives and these are usually present in very small amounts, such as 0.05 to 0.2 weight percent based on the weight of the formulated oil.
Antioxidants are also usually employed in the additive concentrates and lubricants and functional fluids of this invention. Preferred are hindered phenolic antioxidants, methylene bridged alkylphenols, secondary aromatic amines, sulphurized phenols, alkyl phenothiazines, substituted triazines and ureas, and copper compounds such as copper naphthenate and copper oleate, among others. Typically the oil of lubricating viscosity will contain 0.001 to 2.5 weight percent of antioxidant. Particularly preferred are combinations of (i) at least one oil-soluble mononuclear monohydric phenol having a tertiary alkyl group in at least one position ortho to the hydroxyl group and a hydrogen atom or a tertiary alkyl group in the position para to the hydroxyl group, (ii) at least one oil-soluble methylene-bridged tertiary alkyl-substituted polyphenol, and (iii) at least one oil-soluble aromatic secondary amine, the proportions of (i), (ii) and (iii) being such that the weight percentage of nitrogen in component (iii) relative to the total weight of components (i), (ii) and (iii) is in the range of 0.05% to 1.5%, and the weight ratio of monohydric phenols:methylene-bridged polyphenols in the composition is in the range of 15:1 to 1:2. Preferably component (i) in the foregoing composition is an oil-soluble mixture of said mononuclear monohydric phenols. It is likewise preferred that component (ii) of the foregoing composition be an oil-soluble mixture of said methylene-bridged tertiary alkyl-substituted phenols.
Particularly preferred is an antioxidant composition which comprises a combination of (i) an oil soluble mixture of sterically-hindered tertiary alkylated monohydric phenols, (ii) an oil-soluble mixture of sterically-hindered tertiary alkylated methylene-bridged polyphenols, and (iii) at least one oil-soluble aromatic secondary amine, the proportions of (i), (ii) and (iii) being such that the weight percentage of nitrogen in component (iii) relative to the total weight of components (i), (ii) and (iii) is in the range of 0.05% to 1.5%, preferably in the range of 0.1% to 0.8%, and most preferably in the range of 0.3% to 0.7%, and the weight ratio of monohydric phenols:methylene-bridged polyphenols in the composition is in the range of 15:1 to 1:2, preferably in the range of 10:1 to 1:1, and most preferably in the range of 5:1 to 1:1. Preferred secondary aromatic amines are alkyl diphenylamines containing 1 or 2 alkyl substituents each having up to about 16 carbon atoms, phenyl-α-naphthylamine, phenyl-β-naphthylamine, alkyl- or aralkyl-substituted phenyl- α-naphthylamine containing 1 or 2 alkyl or aralkyl groups each having up to about 16 carbon atoms, alkyl- or aralkyl-substituted phenyl-β-naphthylamine containing 1 or 2 alkyl or aralkyl groups each having up to about 16 carbon atoms, and similar compounds. One such preferred compound is available commercially as Naugalube 438L, a material which is understood to be predominantly a 4,4'-dinonyldiphenylamine (i.e., bis(4-non-ylphenyl)amine) wherein the nonyl groups are branched.
Other well known components such as rust inhibitors, wax modifiers, foam inhibitors, copper passivators, sulphur scavengers, seal swell agents, color stabilizers, and like materials can be included in the compositions of this invention, provided of course that they are compatible with the ashless dispersant of this invention and the other component or components being employed.
This invention also includes among its embodiments improved methods of lubricating mechanical parts in the presence of at least one fluoroelastomer surface. In the practice of such methods, the lubrication is effected by means of a lubricating oil or functional fluid containing an ashless dispersant of this invention. The practice of such methods results in a lower -- oftentimes a substantially lower -- amount of degradation of the fluoroelastomer contacted by the lubricating oil or functional fluid containing such ashless dispersant as compared to the amount of degradation that would occur under the same conditions using the same oil or fluid composition containing the same total quantity of the corresponding initial untreated ashless dispersant
Mechanical mechanisms and systems which may be lubricated include crankcases of internal combustion engines; vehicular transmissions; hydraulic systems; hypoid axles; mechanical steering drives in passenger cars, in trucks, and in cross-country vehicles; planetary hub reduction axles and transfer gear boxes in utility vehicles such as trucks; pinion hub reduction gear boxes; synchromesh and synchronizer type gear boxes; power take-off gears; and limited slip rear axles. The ashless dispersant can also be utilized in metal working, machining, and cutting oils such as are applied to work pieces during cutting and shaping operations.

Claims

An oil soluble dispersant composition formable by reacting, concurrently or sequentially in any order, a basic nitrogen-containing ashless dispersant (i) with at least one dibasic acylating agent containing upto 12 carbon atoms per molecule and (ii) with at least one phosphorylating compound selected from phosphorous acid, hypophosphoric acid, metaphosphoric acid, pyrophosphoric acid, hypophosphorous acid, pyrophosphorous acid, phosphinous acid, tripolyphosphoric acid, tetrapolyphosphoric acid, trimetaphosphoric acid, PoCl₃, PCl₃ and PBr₃.
A composition according to claim 1, wherein reaction (i) is conducted prior to reaction (ii).
A composition according to claim 1, wherein reaction (ii) is conducted prior to reaction (i).
A composition according to claim 1, wherein reactions (i) and (ii) are conducted concurrently.
A composition according to any one of claims 1 to 4, wherein reaction (ii) is conducted using phosphorous acid.
A composition according to any one of claims 1 to 5, wherein the acylating agent used in reaction (i) is maleic anhydride, maleic acid, fumaric acid, malic acid or any combination thereof.
A composition according to any one of the preceding claims, wherein the basic nitrogen-containing ashless dispersant is a succinimide dispersant having an average of at least 3 nitrogen atoms per molecule.
A composition according claim 7, wherein the basic nitrogen-containing ashless dispersant is a succinimide dispersant formed from an alkyl or alkenyl succinic acylating agent having an average of at least 40 carbon atoms in the alkyl or alkenyl group and an alkylene polyamine mixture having an average of at least 3 nitrogen atoms per molecule.
A composition according claim 8, wherein the basic nitrogen-containing ashless dispersant is a succinimide dispersant formed from a polyisobutenyl succinic acylating agent derived from polyisobutene having a number average molecular weight in the range of 500 to 10,000 and an ethylene polyamine mixture including cyclic and acyclic structures, said mixture having an average overall composition approximating to a mixture in the range of from triethylene tetramine to pentaethylene hexamine.
A composition according to any one of the preceding claims, wherein the dibasic acylating agent(s) is/are employed in amounts ranging from 0.01 to 0.5 moles per average equivalent of nitrogen in the basic nitrogen-containing ashless dispersant(s), with the proviso that the resultant product contains at least 0.05 equivalent of basic nitrogen, and wherein upto about 5% of phosphorus expressed as weight % of elemental phosphorus, are introduced into the overall final co-reacted dispersant.
A composition according to claim 9, wherein the dibasic acylating agent(s) is/are employed in amounts such that the total mole ratio of (a) dibasic acylating and (b) succinic acylating agent used in forming the basic nitrogen-containing ashless dispersant falls in the range of from 1.5 to 3.5 moles of (a) and (b) per mole of polyamine, and wherein from 0.05 to 2.5% of phosphorus, expressed as weight % of elemental phosphorus, is introduced into the overall final co-reacted dispersant.
A lubricating oil or functional fluid composition comprising a major proportion of an oil of lubricating viscosity and a minor dispersant amount of a dispersant composition as defined in any one of claims 1 to 11.
An additive concentrate comprising a dispersant composition as defined in any one of claims 1 to 11.
A process for preparing an oil soluble dispersant composition as defined in claim 1, which comprises
(a) reacting a basic nitrogen-containing ashless dispersant with at least one dibasic acylating agent having upto 12 carbon atoms in the molecule and with at least one phosphorylating compound selected from phosphorous acid, hypophosphoric acid, metaphosphoric acid, pyrophosphoric acid, hypophosphorous acid, pyrophosphorous acid, phosphinous acid, tripolyphosphoric acid, tetrapolyphosphoric acid, trimetaphosphoric acid, POCl₃, PCl₃ and PBr₃, such reactions being conducted concurrently or sequentially in any order;

(b) reacting a basic nitrogen-containing ashless dispersant phosphorylated with at least one phosphorylating compound selected from phosphorous acid, hypophosphoric acid, metaphosphoric acid, pyrophosphoric acid, hypophosphorous acid, pyrophosphorous acid, phosphinous acid, tripolyphosphoric acid, tetrapolyphosphoric acid, trimetaphosphoric acid, POCl₃, PCl₃ and PBr₃ with at least one dibasic acylating agent containing upto 12 carbon atoms; or

(c) reacting a basic nitrogen-containing ashless dispersant acylated with at least one dibasic acylating agent containing upto 12 carbon atoms, with at least one phosphorylating compound selected from phosphorous acid, hypophosphoric acid, metaphosphoric acid, pyrophosphoric acid, hypophosphorous acid, pyrophosphorous acid, phosphinous acid, tripolyphosphoric acid, tetrapolyphosphoric acid, trimetaphosphoric acid, POCl₃, PCl₃ and PBr₃.
A process according to claim 14, wherein in (a) reaction with the dibasic acylating agent is conducted prior to reaction with the phosphorylating compound.
A process according to claim 14, wherein in (a) reaction with the dibasic acylating agent is conducted after reaction with the phosphorylating compound.
A process according to claim 14, wherein in (a) reaction with the dibasic acylating agent and reaction with the phosphorylating compound are conducted concurrently.
A process according to any one of claims 14 to 17, wherein in (a) the basic nitrogen-containing ashless dispersant is a succinimide dispersant having an average of at least 3 nitrogen atoms per molecule.
A process according to claim 18, wherein in (a) the basic nitrogen-containing ashless dispersant is a succinimide dispersant formed from an alkyl or alkenyl succinic acylating agent having an average of at least 40 carbon atoms in the alkyl or alkenyl group and an alkylene polyamine mixture having an average of at least 3 nitrogen atoms per molecule.
A process according to claim 19, wherein in (a) the basic nitrogen-containing ashless dispersant is a succinimide dispersant formed from a polyisobutenyl succinic acylating agent derived from polyisobutene having a number average molecular weight in the range of 500 to 10,000 and an ethylene polyamine mixture including cyclic and acyclic structures, said mixture having an average overall composition approximating to a mixture in the range of from triethylene tetramine to pentaethylene hexamine.
A process according to any one of claims 14 to 20, wherein in (a) the dibasic acylating agent is maleic acid, maleic anhydride, fumaric acid, malic acid or any combination thereof and the phosphorylating compound is phosphorous acid.
A process according to claim 14, wherein in (b) the phosphorylated basic nitrogen-containing ashless dispersant is a phosphorylated basic nitrogen-containing succinimide.
A process according to claim 14, wherein in (c) the acylated basic nitrogen-containing ashless dispersant is an acylated basic nitrogen-containing succinimide.
A method of lubricating mechanical parts in which a fluoroelastomer surface is in contact with a lubricant or functional fluid, which method is effected by means of a lubricating oil or functional fluid comprising a dispersant composition as defined in any one of claims 1 to 11.