JPH0447720B2 - - Google Patents

Description

[Detailed description of the invention]

BACKGROUND OF THE INVENTION The need for grease compositions capable of providing adequate lubrication at elevated temperatures for extended periods of time is becoming increasingly important. For this reason, various organic thickening agents have been developed, such as thickening agents containing multiple ureido or urea functional groups. For example, U.S. Patent Nos. 3,242,210, 3,243,372 and
No. 3401027 discloses polyurea grease thickeners obtained by reacting monoamines, diamines and diisocyanates or ternary reactant mixtures consisting of monoisocyanates, diisocyanates and diamines. Generally, the reaction product contains a mixture of compounds of various chain lengths and urea contents. However, by careful control of reaction variables such as, for example, the relative amounts of reactants used, the reaction temperature, the rate and order of reactant mixing, a product in which one type of polyurea compound predominates can be obtained. It can be manufactured properly. The polyurea reaction is preferably carried out in the grease carrier and the reaction product can also be used directly as a grease thickener. Greases thickened with polyurea thickeners are superior to older lubricants in many ways under severe service conditions, particularly in maintaining grease consistency at high temperatures; They also have several disadvantages that limit their usefulness under actual conditions of use. For example, polyurea-thickened greases have excellent mechanical property retention at high temperatures (70° C. or higher) and high shear, but tend to soften in consistency when they are subjected to low shear. In fact, the tendency to soften under low shear is considerable, so that when subjected to mechanical action under these conditions the grease exhibits a change in penetration grade, e.g.
This is enough to cause a change from 2NLGI penetration grade to No.1NLGI penetration grade. This change in penetration grade under low shear is particularly tricky as it can occur under actual use conditions, such as when transferring the grease from its original shipping container or during agitation or handling. . As a result, normal handling to make the grease available to the end consumer can change its consistency to an extent that it is not the desired penetration grade for the intended application. Although the change in consistency is reversible, as high-shear treatment of softened grease can return it to its original consistency, this often requires returning the softened grease to the compounder for processing. There is. Description of the Prior Art US Pat. No. 4,104,177 and US Pat. No. 4,111,822 disclose the formula, (wherein A is an alkylene group of 2 to 4 carbon atoms, n is an integer of 0 to 3, X is H or Z, and Y is H, 12 to 22 carbon atoms. Polyurea-thickening greases are disclosed that contain certain acrylated alkylene polyamines selected from the group consisting of alkyl groups having an acyl group and Z being an acyl group. These additives are disclosed to serve to improve mechanical stability at ambient temperatures and to improve rust protection in polyurea thickened greases. As will be readily appreciated by those skilled in the art, the polyamines described above are not polymers due to their low molecular weight and limited number of monomer units. SUMMARY OF THE INVENTION A major amount of the lubricating oil base vehicle
oil base vehicle), characterized in that it consists of an amount of a polyurea gellant sufficient to thicken the base vehicle to a certain grease consistency and a small amount of a polymer having a pKa value of 5.0 or more. It is a grease composition. DETAILED DESCRIPTION OF THE INVENTION The grease compositions of the present invention consist of a combination of at least three components: (1) a lubricating oil base vehicle, (2) a polyurea gelling agent, and (3) a polymer. Other additives may also be present, but the three components mentioned above are absolutely essential. The lubricant-based vehicles and the polyurea gelling agents are well known to those skilled in the art. Any lubricating oil base vehicle commonly used in greases can be used. Generally, the base vehicle will constitute 50-99% by weight of the final grease composition. The base vehicle is most commonly a petroleum or synthetic base oil. Polyurea gelling agents for use in this combination are also well known in the grease industry and can be prepared by conventional methods. For example, U.S. Pat. No. 3,242,210 describes a method for making polyurea-thickened greases suitable for use in the combination of the present invention, the disclosure of which is incorporated herein by reference. The polyurea is used in an amount sufficient to thicken the base vehicle to a grease consistency. When used as a gelling agent, the polyurea is usually present in an amount of at least about 0.5% by weight and more usually from about 1 to 25 or more percent by weight. The third essential component in the grease of the invention is:
Certain polymers (different from polyurea gelling agents) have pKa values of 5.0 or higher. The term "polymer" as used in the present invention refers to a large molecule consisting of an indeterminate number of monomers, as distinguished from oligomers consisting of a very small number of monomer units, such as dimers, trimers, tetramers, etc. is called. For purposes of clarity in the present invention, the term "oligomer" is used herein to mean a molecule containing less than 6 monomer units, and the term "polymer" refers to a molecule containing 6 or more monomer units. Define it as a molecule. Generally, polymers useful in the present invention include:
It will be a high molecular weight polymer having a molecular weight of 1000 or more and preferably 2000 to 5000000 or more and most preferably within the range of 5000 to 100000. Addition of this polymer to polyurea grease compositions significantly improves the low shear stability of the compositions. It is not completely understood why this polymer improves the low shear stability of polyurea thickened greases. However, it is believed that the interaction of hydrogen bonds between the polyurea molecules or fibers and the polymer is responsible for the low shear stability. It is therefore preferable to use polymers that are capable of hydrogen bonding interactions with the polyurea molecules. Generally these polymers will have pKa values of 5.0 or higher and preferably 7.0 or higher. [pKa] refers to the -log acid dissociation constant, which is well known in the art. Such polymers will be characterized by the presence of hydrogen bond donor and/or hydrogen bond acceptor groups. The most common such polymers will generally contain oxygen and/or nitrogen. Representative types of polymers used in the present invention include polyamides, polyurethanes, polyoxides, polysulfides, and polyamines. Typical polyamides include polyglycine, poly(β-alanine), or poly(3-aminopropionic acid), poly(4-aminobutyric acid), poly(5-aminovaleric acid), poly(6-aminocaproic acid). ), poly(7-aminoenantoic acid), poly(8-aminocaprylic acid), poly(9-aminopelargonic acid),
Included are poly(10-aminocapric acid), poly(11-aminodecanoic acid) and poly(12-aminolauric acid). Representative polyurethanes include poly(trimethylene ethylene-urethane). Representative polyoxides include polyformaldehyde, polyacetaldehyde, poly(ethylene oxide), poly(propylene oxide) and poly(trimethylene oxide). Representative polysulfides include poly(ethylene trimethylene sulfide) and polyethylene sulfide. Representative polyamines include poly(ethylene trimethyleneamine) and polyvinylamine. Other representative polymers for use in the present invention include polyvinyl alcohol, ethylene/vinyl acetate copolymers, polyvinylpyrrolidone and polyacrylamide. Particularly preferred are ethylene/vinyl acetate copolymers. A small but effective amount of polymer is used to improve the low shear stability of this polyurea thickened grease. Generally comprises 0.1 to 20% or more of the polymer by weight of the final grease composition, and preferably 1 to 10% and most preferably 2 to 6%.
Will. Reference is made to the following examples to more fully explain the invention. Examples Examples 1 to 4 Polyurea grease containing polyvinylpyrrolidone A mixture of 85.76 g (0.32 mol) oleylamine [Armeen O] and 750.0 g oil was heated and stirred in 3 stainless steel beakers to 75°C. I made it. Then 9.6 g (0.16 moles) of ethylene diamine was added, and then a mixture of 55.68 g (0.32 moles) of toluene diisocyanate in 250 g of oil was added. This reaction mixture was heated at 75°C.
The temperature was maintained for 30 minutes. 7.67 g of NaNO ₂ dissolved in a minimum amount of water was then added and the temperature of the reaction mixture was increased. At 120°C 75g polyvinylpyrrolidone and 3.1g aromatic amine antioxidant were added and heated to 150°C. The reaction mixture was then maintained at 150°C for 30 minutes,
Then it was cooled to 100°C. 4.43g of a second common antioxidant was added and the mixture was stirred at 100°C for 15 minutes and allowed to cool to 70°C.
78.22g of conventional rust inhibitor was added and additional oil was added for a total of 1200g of added oil. The cooled grease was milled through a 3-roll mill three times.
The oil used was common mineral oil (Chevron Neutral oil 115). The low shear stability of the grease was determined by measuring the softening rate using ASTM Worked Penetration after 60 strokes (ASTMD-1403) and after 100,000 strokes (ASTM D-217). Tested by. This grease was also subjected to a Shell Roll Test.
(ASTM D-1831). Improved low shear stability is evidenced by relatively low softening rates. The results are shown in Table I. Table I also shows the results of using other polymeric additives with the polyurea thickened grease base described above, designated Base Grease "A" in Table I. Examples 5-12 Polyurea greases made using synthetic hydrocarbon bases 1500 g of oleylamine (Adogen)
172] and 10750g Mobil MCP−
The mixture of 151 synthetic base oils was heated and stirred to 75°C. When the mixture reached 75°C, 168g of ethylenediamine was added. When its temperature becomes constant at 75°C, 3750g Mobil MCP−
836g of toluene diisocyanate in 151 was added. An additional 500 g of Mobil MCP-151 was then added and the mixture was stirred and held at 75°C for 1/2 hour. 1425 g of this mixture alone or a mixture containing 75 g of the polymers listed in Table I were subsequently heated with stirring to 150 DEG C., kept at that temperature for 30 minutes and then cooled to room temperature. This composition was passed through a 3-roll mill three times. Test results for this grease with various polymer additives are shown in Table I. The base grease prepared above is designated as base grease "B" in Table I. Example 13 Prior Art A polyurea grease containing an acrylated alkylene amine, specific additive A (Table I) in US Pat. No. 4,104,177, was prepared. This additive combines Duomeen T and oleic acid based on the method specified in the aforementioned patent.
Produced by reaction at 190°C. This additive was tested for low shear stability at a concentration of 5% by weight in the same polyurea containing the same base grease used in Examples 5-12. The results are shown in Table I.

【table】

TABLE As those skilled in the art will appreciate, the results in Table I demonstrate the effectiveness of the polymers of the present invention in improving the low shear stability of polyurea-containing greases. Examples 9 and 10 demonstrate that polymers with pKa values less than 5 are effective in improving the low shear stability of the grease. Example 13 shows that the polymers of the present invention have been shown to improve the low shear stability of their greases.
It further shows that it is superior to the acrylated alkylene amine of No. 4104177.

Claims (1)

Claims: 1. a major amount of a lubricating oil base vehicle, an amount of a polyurea gelling agent sufficient to thicken the base vehicle to a grease consistency, and
small amounts of polyamides, with pKa values greater than or equal to 5.0;
A grease composition comprising a polymer selected from the group consisting of polyurethane, polyamine, polyoxide, polyacrylamide, polyvinyl alcohol, ethylene-vinyl acetate copolymer and polyvinylpyrrolidone. 2. The grease composition according to item 1 above, wherein the grease contains 0.1 to 20% by weight of the polymer. 3. The grease composition according to item 2 above, wherein the polymer has a molecular weight of 1000 or more. 4. The grease composition according to item 3 above, wherein the polymer has a molecular weight within the range of 2,000 to 5,000,000 and a pKa value of 7.0 or more. 5. The grease composition according to item 3 or 4, wherein the grease contains 1 to 10% by weight of the polymer.