Imide composition and preservative composition containing the same

Abstract

The present invention provides an imide composition obtained by the following steps: (a) reacting a dianhydride with a diamine in the presence of a solvent at a temperature in the range of 20-80°C, wherein the molar ratio of the dianhydride (A) to the diamine (B) is in the range of 0.25-4 (A / B) to form an imide precursor; and (b) subjecting the imide precursor formed in step (a) to a heat treatment at a temperature in the range of 80-150°C in the presence of a solvent to convert the imide precursor into an imide, thereby forming an imide composition. The present invention also provides: a preservative composition comprising the imide composition; a metal product comprising a coating of the preservative composition; a process for preparing the imide composition; use of the imide composition to prevent pseudo-Brinell indentations in rolling bearing systems; use of the preservative composition to prevent pseudo-Brinell indentations in rolling bearing systems.

Description

Technical Field

[0001] The present invention relates to: an imide composition; an anticorrosive composition comprising the imide composition; a metal product having a coating layer comprising the imide composition or the anticorrosive composition coated thereon; a process for preparing the imide composition; a process for forming a coating layer on a metal product; use of the imide composition for preventing and / or reducing false Brinell indentations in a rolling bearing system; and use of the anticorrosive composition for preventing and / or reducing false Brinell indentations in a rolling bearing system. Background Art

[0002] Inhibitor compositions are widely used to protect bearings and other structural components from damage such as corrosion, wear and surface cracks. Damage to bearings and rolling bearing systems will affect their performance and function under working conditions during their service life and affect the life of the bearings.

[0003] A common type of bearing damage is fretting wear. Fretting refers to any situation where the mating surfaces are subjected to small amplitude reciprocating sliding or rolling motions. Fretting may occur between mating surfaces that are intended to be fixed but are subjected to small oscillatory motions due to vibration. In various applications, bearings in seats or bearings on shafts may be subjected to small amplitude dynamic loads or bending moments that introduce small amplitude relative motions. Fretting wear may cause sticking, may amplify vibrations, cause wear and fatigue of components, and may eventually lead to system failure. Fretting wear is characterized by the retention of wear debris in the contact due to the small vibration amplitude of the fretting. Under normal atmospheres, oxidation of the debris is involved, and the terms fretting corrosion and fretting wear are often used. The term "false brinelling" is specifically used for fretting wear of point contacts in ball bearings. The bearings of passenger cars are subjected to small oscillatory motions, and as a result, false brinelling may appear after the car is transported. The appearance of fretting wear in ball-ring contact is similar to the brinelling indentation used in hardness measurement of bulk materials, that is, false brinelling. System vibration and / or cyclic loading can both cause mating surfaces to slide relative to each other, and two different terms are used in these regards. A distinction is often made between fretting wear and fretting fatigue. Fretting fatigue generally refers to dynamic body stresses that include tensile stresses of the component. Fretting conditions cause crack initiation and development at stresses below the fatigue limit of the component. Both fretting wear and fretting fatigue involve dynamic loading. Fretting wear is an adhesive wear mechanism. The difference between fretting wear and fretting fatigue is the dominance of dynamic body stresses (generating tensile stresses) relative to (dynamic) shear stresses in the failure mode involved. This tensile stress can be the cause of component penetration cracks. Shear stresses decrease fairly quickly with distance below the surface, and in the absence of tensile body stresses, cracks are confined to shallow surface areas. Under these conditions, fretting wear masks fretting fatigue and cracks will be confined to shallow depths.

[0004] Another common type of bearing damage is tribo-corrosion, which occurs in the form of a chemical reaction activated by relative micro-movements between contacting surfaces under certain conditions inside the bearing. Tribo-corrosion occurs in the form of fretting corrosion or vibration corrosion.

[0005] Fretting corrosion occurs when there is relative movement between the bearing ring and the shaft or seat (for example, due to a fit that is too loose or too tight). Due to the relative movement between the mating surfaces, small particles of material can break away from the surface and these particles can oxidize rapidly when exposed to oxygen in the air.

[0006] Vibration corrosion (also called pseudo-Brinelling) is produced in the rolling element-raceway contact area due to micro-movements under cyclic vibrations and / or the elasticity of the elastic contact. Depending on the intensity of the vibrations, the lubrication conditions and the loads, a combination of corrosion and wear occurs, forming shallow depressions in the raceways. In the case of stationary bearings (e.g., bearings during passenger car transportation), depressions appear at the rolling element pitch and are usually discolored or shiny. Bearings and other metal components are machined, cleaned, heated and otherwise chemically treated and may be exposed to a variety of aggressive chemicals and corrosive compounds during their production, from which the metal surfaces need to be protected.

[0007] Rust inhibitors and corrosion inhibitors provide resistance to these liquids and environments that promote corrosion. After manufacturing, the bearing surface can be immersed in an anti-corrosion liquid or sprayed with an anti-corrosion liquid. Temporary protective films can protect metal and bearing surfaces from corrosion during the shipment and storage of metal components. Corrosion inhibitors can be used as additives in lubricating oils or greases, or even as part of processing liquids. The task of corrosion inhibitors is to prevent surface corrosion as long as the carrier fluid or grease can form a film on the metal surface like a corrosion inhibitor. Rust inhibitors are usually composed of additives dissolved in a medium. In an anti-corrosion composition, the medium can be as much as 80wt.% or higher. Commonly used media are solvents, naphthenic oils or paraffin oils. Solvents can have the ability to evaporate completely, while oils are usually not completely evaporated after application, and the oily film remains on the surface. Water can evaporate partially or completely, and therefore can still be part of the final film even after use or drying. Examples of additives for anti-corrosion agents are metal salts, waxes, oils, petroleum-based products, mineral spirits or other types of additives. Waxes and metal salts are usually used as ingredients in anti-corrosion agents. Typical examples of metal salts are calcium sulfonate salts, barium sulfonate salts, sodium sulfonate salts. The use of these typical metal salts does not provide completely satisfactory corrosion protection and requires waxes. Some of these metal salts are limited in use due to their strict safety and environmental regulations or simply due to their poor corrosion resistance. Waxes are prone to inconsistent quality, unstable crystallinity, and may present sprayability issues.

[0008] Conventional preservative compositions usually consist of a metal-containing compound and a wax. Typical metal-containing compounds used for this purpose are calcium sulfonate salts incorporated in solvents or oils. Another disadvantage of conventional preservative compositions is that their effectiveness leaves considerable room for improvement.

[0009] The object of the present invention is to provide a novel method for attractively preventing and / or reducing false Brinell indentations, in which no metal salts and waxes are used. The novel method is based on the preparation of a novel chemical composition which exhibits excellent anti-false Brinell indentation properties.

[0010] Another object of the present invention is to provide a preservative composition comprising the novel chemical composition. Summary of the invention

[0011] Surprisingly, it has now been found that a specific imide composition prevents and / or reduces false Brinelling in an excellent manner.

[0012] Therefore, the present invention provides an imide composition, which can be obtained by a process comprising the following steps:

[0013] (a) reacting a dianhydride with a diamine in the presence of a solvent at a temperature in the range of 20-80° C., wherein the molar ratio of the dianhydride (A) to the diamine (B) is in the range of 0.25-4 (A / B), thereby forming an imide precursor; and

[0014] (b) subjecting at least a portion of the imide precursor formed in step (a) to a heat treatment at a temperature in the range of 80-150° C. in the presence of a solvent to convert at least a portion of the imide precursor into imide, thereby forming the imide composition.

[0015] The imide composition according to the present invention exhibits unique properties in preventing and / or reducing false Brinell marks. When compared to conventional preservative compositions comprising calcium sulfonate salts, the present imide composition prevents and / or reduces false Brinell marks in an improved manner. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 IR spectra of three examples of the present invention are shown.

[0017] Figure 2 The performance change of Example 1 of the present invention is shown.

[0018] Figure 3 The performance change of Example 2 of the present invention is shown.

[0019] Figure 4 The performance change of Example 3 of the present invention is shown. DETAILED DESCRIPTION

[0020] The imide composition according to the present invention can be obtained by a process comprising step (a) and step (b).

[0021] In step (a), a dianhydride is reacted with a diamine in the presence of a solvent at a temperature in the range of 20-80°C.

[0022] Suitably, the dianhydride used in step (a) is selected from the group consisting of pyromellitic dianhydride, perylene tetracarboxylic dianhydride, 4,4'-oxydiphthalic anhydride, 4,4-bisphenol A dianhydride, bisphenol diether dianhydride, 4,4'-(4,4'-isopropylidenediphenoxy)bis(phthalic anhydride), naphthalene tetracarboxylic dianhydride, ethylene dianhydride, naphthalene dianhydride, phenanthrene dianhydride, anthracene dianhydride and benzoquinonetatracarboxylic dianhydride. Most preferably, the dianhydride is pyromellitic dianhydride.

[0023] Suitably, the diamine used in step (a) is selected from the group consisting of aliphatic linear unbranched, branched or cyclic diamines, unsaturated diamines, aromatic diamines, diamines not directly attached to an aromatic ring (e.g., benzylamine, diphenyldiamine, dinaphthylenediamine and hexamethylenediamine). Preferably, the diamine is selected from the group consisting of dodecanediamine, decanediamine, ethylenediamine, butanediamine, diamineoctane, methyldiamine and hexamethylenediamine. More preferably, the diamine is hexamethylenediamine.

[0024] Step (a) is performed at a temperature in the range of 20-80°C, preferably in the range of 40-60°C, and more preferably in the range of 45-55°C.

[0025] In step (a), there is a solvent. Preferably, the solvent is selected from the group consisting of a polar solvent, a non-polar solvent and an aprotic polar solvent. Suitable examples of polar solvents include formic acid, n-butanol, isopropanol, nitromethane, ethanol, methanol, acetic acid and water. Suitable examples of non-polar solvents include hexane, benzene, toluene, 1,4-dioxane, chloroform and ether. Suitable solvents for aprotic solvents include dichloromethane, N-methylpyrrolidone, tetrahydrofuran, ethyl acetate, acetone, dimethylformamide, acetonitrile, dimethyl sulfoxide and propylene carbonate. Preferred solvents used according to the present invention include dimethyl sulfoxide, acetone, chloroform, ether, n-hexane, benzene, N-methyl-2-pyrrolidone, dimethylformamide, dimethylacetamide, N-methyl-2-pyrrolidone and water.

[0026] In step (a), a single solvent or a mixture of solvents may be used.

[0027] Suitably, the solvent is present in an amount such that the weight ratio of the sum of the dianhydride (A) and the diamine (B) to the solvent (C) is in the range of 0.005-0.5 ((A+B) / C), preferably in the range of 0.01-0.1 ((A+B) / C).

[0028] At least a portion of the imide precursor as formed in step (a) is subjected to step (b). Preferably, the entire imide precursor as formed in step (a) is subjected to step (b).

[0029] At least a portion of the imide precursor as formed in step (a) may be subjected to heat treatment before it is subjected to step (b). Preferably, the entire amount of the imide precursor as formed in step (a) is subjected to heat treatment before it is subjected to step (b). In such heat treatment, the solvent used in step (a) may be evaporated to obtain an imide precursor in powder form. Such heat treatment may be suitably carried out at a temperature in the range of 40-200° C., preferably at a temperature in the range of 80-150° C. Subsequently, the imide precursor thus obtained may be mixed with the solvent in step (b).

[0030] Therefore, the present invention also provides an imide composition, which can be obtained by a process comprising the following steps:

[0031] (a) reacting a dianhydride with a diamine in the presence of a solvent at a temperature in the range of 20-80° C., wherein the molar ratio of the dianhydride (A) to the diamine (B) is in the range of 0.25-4 (A / B), thereby forming an imide precursor;

[0032] (b) subjecting at least a portion of the imide precursor as formed in step (a) to a heat treatment; and

[0033] (c) subjecting at least a portion of the imide precursor as obtained in step (b) to a heat treatment at a temperature ranging from 80 to 150° C. in the presence of a solvent to convert at least a portion of the imide precursor into imide, thereby forming the imide composition.

[0034] Preferably, the entire amount of the imide precursor formed in step (a) is subjected to step (b).

[0035] Preferably, the entire amount of the imide precursor as obtained in step (b) is subjected to step (c).

[0036] In step (a), the molar ratio of dianhydride (A) to diamine (B) is in the range of 0.25-4 (A / B), preferably in the range of 0.33-1 (A / B), and more preferably in the range of 0.45-1 (A / B).

[0037] In step (a), the solubility of the dianhydride is suitably in the range of 0.0006 to 1 gram per milliliter of solvent.

[0038] In step (a), the solubility of the diamine is suitably in the range of 0.0006 to 1 gram per milliliter of solvent.

[0039] Preferably, in step (a), the dianhydride is pyromellitic dianhydride and the diamine is hexamethylenediamine.

[0040] In step (a), an imide precursor is formed, which is converted into an imide in step (c), thereby forming the imide composition according to the present invention.

[0041] In the case of using pyromellitic dianhydride and a diamine, the imide precursor will have the following general formula (I)

[0042] (I)

[0043]

[0044] The NH3+ groups as shown in the general formula (I) may also be NH2 groups in the same molecule. Some molecules of the general formula (I) contain NH3+ groups and other molecules contain NH2.

[0045] In step (a), the pH is suitably in the range of 5 to 9, preferably in the range of 6 to 8. The total acid number (TAN) is a maximum of 200, and the total base number (TBN) is a maximum of 200.

[0046] In step (b), at least a portion of the imide precursor formed in step (a) is subjected to heat treatment at a temperature ranging from 80 to 150° C. in the presence of a solvent to convert at least a portion of the imide precursor into imide to form an imide composition.

[0047] Preferably, the heat treatment is performed at a temperature in the range of 110-130°C, more preferably in the range of 115-125°C.

[0048] In step (b), there is a solvent. Preferably, the solvent is selected from the group consisting of a polar solvent, a non-polar solvent and an aprotic polar solvent. Suitable examples of polar solvents include formic acid, n-butanol, isopropanol, nitromethane, ethanol, methanol, acetic acid and water. Suitable examples of non-polar solvents include hexane, benzene, toluene, 1,4-dioxane, chloroform and ether. Suitable solvents for aprotic solvents include dichloromethane, N-methylpyrrolidone, tetrahydrofuran, ethyl acetate, acetone, dimethylformamide, acetonitrile, dimethyl sulfoxide and propylene carbonate. Preferred solvents used according to the present invention include dimethyl sulfoxide, acetone, chloroform, ether, n-hexane, benzene, N-methyl-2-pyrrolidone, dimethylformamide, dimethylacetamide, N-methyl-2-pyrrolidone and water.

[0049] In step (b) a single solvent or a mixture of solvents may be used.

[0050] Suitably, in step (b), an amount of solvent is present such that the weight ratio of imide precursor (D) to solvent (E) is in the range of 0.001-1 (D / E), preferably in the range of 0.01-0.5 (D / E).

[0051] In step (b), the pH is suitably in the range of 5 to 9, preferably in the range of 6 to 8. The total acid number (TAN) is a maximum of 200, and the total base number (TBN) is a maximum of 200.

[0052] In steps (a) and (b), the same or different solvents may be used. Suitably, step (a) is carried out in the presence of an aprotic polar solvent and step (b) is carried out in the presence of a polar solvent and / or an aprotic solvent.

[0053] In this step (b), different solvents may be used at different stages of the step. For example, a mixture of different solvents may be used in the first stage of step (b), while a solvent such as N-methyl-2-pyrrolidone may be used in the second stage of step (b), and then water may be used in step (b). The advantage of this method is that the pseudo-Brinell indentation performance is affected in a positive way.

[0054] The imide formed during step (b) may be subjected to an evaporation treatment, wherein the first solvent used in step (b) will be removed to obtain a dry powder of the imide. Subsequently, a second solvent such as water may be added to the dry imide powder.

[0055] In one embodiment of the present invention, the imide precursor formed in step (a) can be applied to the surface of the metal article. For example, it can be carried out by brushing, dipping, spraying, whipping or rubbing the imide precursor onto the surface of the metal article in liquid form (i.e., dissolved in a solvent). The metal surface can be preheated to the target process temperature of step (b), or after being applied to the metal surface, the coating formed with the imide precursor will be heated to the target temperature of step (b).

[0056] Therefore, the present invention also provides a process for forming a coating on the surface of a metal product, the process comprising the following steps:

[0057] (a) reacting a dianhydride with a diamine in the presence of a solvent at a temperature in the range of 20-80° C., wherein the molar ratio of the dianhydride (A) to the diamine (B) is in the range of 0.25-4 (A / B), thereby forming an imide precursor;

[0058] (b) heating the surface of the metal article to a temperature in the range of 80-150°C; and

[0059] (c) applying at least a portion of the reaction mixture as obtained in step (a) and dissolved in a solvent or at least a portion of the imide precursor as formed in step (a) and dissolved in a solvent to a surface of a metal article to form a coating thereon, thereby forming a coating of the imide composition on the surface of the metal article.

[0060] The present invention also provides a process for forming a coating on the surface of a metal product, the process comprising the following steps:

[0061] (a) reacting a dianhydride with a diamine in the presence of a solvent at a temperature in the range of 20-80° C., wherein the molar ratio of the dianhydride (A) to the diamine (B) is in the range of 0.25-4 (A / B), thereby forming an imide precursor;

[0062] (b) applying at least a portion of the reaction mixture as obtained in step (a) and dissolved in a solvent or at least a portion of the imide precursor as formed in step (a) and dissolved in a solvent to a surface of a metal article to form a coating thereon; and

[0063] (c) subjecting the coating formed in step (b) to a heat treatment to convert at least a portion of the imide precursor into imide, thereby forming an imide-containing coating on the surface of the metal article.

[0064] In the case of using pyromellitic dianhydride and a diamine, the imide formed in step (b) will have the following general formula (II):

[0065] (II)

[0066]

[0067] In step (b), three additional imide precursors will be formed, which have structures different from the imide precursor formed in step (a). These three additional imide precursors will generally have the following general formulas (III), (IV) and (V).

[0068] (III)

[0069]

[0070] (IV)

[0071]

[0072] (V)

[0073]

[0074] Suitably, the imide composition according to the invention comprises an imide, an imide precursor as formed in step (a), three additional imide precursors formed in step (b) and a solvent present in step (a) and / or step (b). After step (b), the imide composition is typically cooled to ambient temperature before use as a preservative composition.

[0075] When the imide composition is applied to a metal product such as a bearing, heat will be generated under the operating conditions, as a result of which the unreacted imide precursor obtained in step (a) and present in the imide composition can be converted into an imide, and the imide can form a coating thereon during the operation of the bearing. In addition, under such operating conditions, the imide and the three additional imide precursors will eventually be converted into the polyimide of general formula (VI), and the polyimide thus obtained will form a coating on the bearing surface.

[0076] (VI)

[0077]

[0078] The present invention also provides a preservative composition comprising the imide composition according to the present invention. In addition to the present imide composition, the preservative composition may contain known additives such as rust inhibitors and corrosion inhibitors. The imide composition and the preservative composition may also contain lanolin and one or more waxes.

[0079] The anticorrosive composition according to the present invention also includes an antirust anticorrosive composition and an anticorrosive anticorrosive composition.

[0080] Suitably, the preservative composition comprises 0.2-50 wt.% of the imide composition, preferably at least 0.5-40 wt.% of the imide composition, more preferably at least 0.5-30 wt.% of the imide composition, based on the total weight of the preservative composition.

[0081] Typical techniques for applying the anticorrosive composition to metal surfaces such as bearing surfaces are dipping, spraying, brushing or any other techniques that physically or mechanically apply the anticorrosive composition to the surface. Can be established by using, for example, a roller or a scraper. Before the anticorrosive composition is applied to the surface, a pre-cleaning or washing step can be applied to remove oil residues and water residues from the metal surface. Then, after the pre-cleaning step, the anticorrosive composition is applied to the surface.

[0082] The present invention also provides a process for preparing an imide composition, the process comprising the following steps:

[0083] (a) reacting a dianhydride with a diamine in the presence of a solvent at a temperature in the range of 20-80° C., wherein the molar ratio of the dianhydride (A) to the diamine (B) is in the range of 0.25-4 (A / B), thereby forming an imide precursor; and

[0084] (b) subjecting at least a portion of the imide precursor formed in step (a) to a heat treatment at a temperature in the range of 80-150° C. in the presence of a solvent to convert at least a portion of the imide precursor into imide, thereby forming the imide composition.

[0085] Preferably, the entire amount of the imide precursor formed in step (a) is subjected to step (b).

[0086] The present invention also provides a process for preparing an imide composition, the process comprising the following steps:

[0087] (a) reacting a dianhydride with a diamine in the presence of a solvent at a temperature in the range of 20-80° C., wherein the molar ratio of the dianhydride (A) to the diamine (B) is in the range of 0.25-4 (A / B), thereby forming an imide precursor;

[0088] (b) subjecting at least a portion of the imide precursor as formed in step (a) to a heat treatment; and

[0089] (c) subjecting at least a portion of the imide precursor as obtained in step (b) to a heat treatment at a temperature ranging from 80 to 150° C. in the presence of a solvent to convert at least a portion of the imide precursor into imide, thereby forming the imide composition.

[0090] Preferably, the entire amount of the imide precursor formed in step (a) is subjected to step (b).

[0091] Preferably, the entire amount of the imide precursor as obtained in step (b) is subjected to step (c).

[0092] The present invention also relates to a metal product having a coating on which the coating comprises the present imide composition or the preservative composition according to the present invention. Suitably, the metal component is a component of a linear motion system, a rolling element, a plain bearing, a ball bearing, a roller bearing, a gear or a coupling. Preferably, the metal product is a bearing. The imide composition according to the present invention has the advantage that it has very attractive film-forming properties that allow excellent coatings to be formed on metal products.

[0093] Suitably, the coating has a thickness in the range of 0.5-40 microns, preferably in the range of 2-20 microns. The thickness of the coating can be measured by known techniques. For example, determining the specific weight of a particular board as is (without coating or preservative) and the weight of the same board treated with a preservative or coating enables the weight difference to be calculated. Since the surface area is precisely known, the thickness of the coating or anticorrosive film can be calculated.

[0094] The present invention also provides a process for forming a coating on the surface of a metal product, the process comprising the following steps:

[0095] (a) reacting a dianhydride with a diamine in the presence of a solvent at a temperature in the range of 20-80° C., wherein the molar ratio of the dianhydride (A) to the diamine (B) is in the range of 0.25-4 (A / B), thereby forming an imide precursor;

[0096] (b) subjecting at least a portion of the imide precursor as formed in step (a) to a heat treatment at a temperature in the range of 80-150° C. in the presence of a solvent to convert at least a portion of the imide precursor into imide, thereby forming the imide composition; and

[0097] (c) applying at least a portion of the imide composition formed in step (b) to a surface of a metal article to form a coating thereon.

[0098] Preferably, the entire amount of the imide precursor formed in step (a) is subjected to step (b).

[0099] Furthermore, the present invention relates to the use of the present imide composition for preventing and / or reducing false brinelling in rolling bearing systems.

[0100] The imide composition or the corrosion inhibitor composition according to the present invention can be used to prevent and / or reduce fretting wear or pseudo-Brinell indentation and / or static corrosion, stress corrosion cracking or any other form of corrosion and / or any form of corrosion of components, surfaces or metal products (such as shell bearing seats, shaft bearing seats, spacer surfaces, guide surfaces, seal surfaces, seal seat surfaces or any other surfaces facing oscillating motion and / or vibration). The imide composition or the corrosion inhibitor composition according to the present invention can be used on the surface of metal products, but can also be used on non-metal surfaces (such as plastic material surfaces, glass material surfaces and plastic material surfaces).

[0101] Furthermore, the invention relates to a corrosion inhibitor composition according to the invention for preventing and / or reducing false brinelling in rolling bearing systems, linear motion systems, plain bearings, ball bearings, roller bearings, gears or couplings.

[0102] The imide composition or preservative composition used according to the present invention may be in the form of a grease, an oil or a paste.

[0103] Example

[0104] Example 1

[0105] The imide composition according to the present invention is prepared as follows. In step (a), 0.73g of pyromellitic dianhydride and 0.77g of hexamethylenediamine are mixed together and stirred for 1 minute at a temperature of 50°C in the presence of 150ml of N-methyl-2-pyrrolidone as an aprotic polar solvent. Pyromellitic dianhydride (A) and hexamethylenediamine (B) are applied in a molar ratio of 1:2 (A / B). The product thus obtained is dried at 120°C for 5 minutes. The resulting bulk material is cooled to room temperature. Then in step (b), 1wt.% of the bulk material is mixed with 99wt.% of water and heated to 120°C. The product is then applied to the surface of the steel component and cured at 120°C for 5 minutes. The imide composition thus obtained contained 99 wt.% of water and 1 wt.% of imide having the following IR spectrum showing the presence of poly(2,2,4- / 2,4,4-trimethylhexamethylenepyromellitic acid imide), pyromellitic acid amide and polyamide.

[0106] Figure 1 IR spectra of three embodiments of the present invention are shown.

[0107] The following performance tests were performed on the imide composition:

[0108] The performance test was conducted under oscillation conditions of 100 μm at 20 Hz, a Hertzian contact pressure of 1 GPa, and in contact with a urea-based grease having 95 cSt at 40°C. Figures 2 to 4The coefficient of friction during the test is shown (lower line), no color was used in the patent application.

[0109] Figure 2 The performance difference of the first embodiment of the present invention is shown.

[0110] exist Figure 3 The performance differences compared to commercially available corrosion and rust inhibitors are shown in. Figure 3 The upper line in shows the equivalent test results using a benchmark commercial preservative. Nine preservatives have been tested and Figure 3 As shown by the upper line in , all corrosion inhibitors show a rapid increase in friction and wear already after a few oscillation cycles. The red line also represents the applied urea-based grease. This grease has very poor pseudo-Brinell indentation performance, and friction and wear are observed immediately after the start of the test. The performance of the corrosion inhibitors of Examples 1, 2 and 3 is shown in Figure 2 , Figure 3 and Figure 4 In other words, no matter what type of grease is used, when the embodiments of the present invention are applied, good performance against false brinelling is shown.

[0111] Example 2

[0112] The imide composition according to the present invention is prepared as follows. In step (a), 2.36 g of pyromellitic dianhydride and 2.52 g of hexamethylenediamine are mixed together and stirred for 5 minutes at a temperature of 50° C. in the presence of 50 ml of N-methyl-2-pyrrolidone as an aprotic polar solvent. Pyromellitic dianhydride (A) and hexamethylenediamine (B) are applied in a molar ratio of 1:2 (A / B). The product is dried at 120° C. for 5 minutes. The resulting bulk material is cooled to room temperature. In step (b), 1 wt.% of the bulk material is mixed with 70 wt.% of water and 30 wt.% of N-methyl-2-pyrrolidone, and the mixture is heated to 120° C. The product is then applied to the surface of the steel component and cured at 120° C. for 5 minutes. The imide composition thus obtained has a final concentration of less than 1 wt.% diluted in a mixture of 75 wt.% of water and 25 wt.% of N-methyl-2-pyrrolidone. The imide composition thus obtained contained the same imide as that prepared in Example 1, and its IR spectrum was shown at Figure 1 middle.

[0113] The imide composition was then impregnated on a bearing steel plate, which was then subjected to the same performance test as used in Example 1. The performance test was conducted under oscillation conditions of 100 μm at 20 Hz, Hertzian contact pressure of 1 GPa, and in contact with urea-based grease having 95 cSt at 40°C. Figure 3 The coefficient of friction during the test is shown. Figure 3 shown.

[0114] Figure 3 The performance difference of Example 2 of the present invention is shown.

[0115] Example 3

[0116] This example was carried out in the same manner as Example 1, except that the polar solvent water was now used instead of N-methyl-2-pyrrolidone.

[0117] The imide composition was then impregnated on a bearing steel plate, which was then subjected to the same performance test as used in Example 1. The performance test was conducted under oscillation conditions of 100 μm at 20 Hz, Hertzian contact pressure of 1 GPa, and in contact with urea-based grease having 95 cSt at 40°C. Figure 4 The coefficient of friction during the test is shown.

[0118] Figure 4 The performance difference of Example 3 of the present invention is shown.

Claims

1. An imide composition, the imide composition is obtained by a method comprising the following steps: (a) reacting a dianhydride with a diamine in the presence of a solvent at a temperature in the range of 20-80° C., wherein: The molar ratio of dianhydride (A) to diamine (B) is in the range of 0.25-4 (A / B), thereby forming an imide precursor; and (b) subjecting at least a portion of the imide precursor as formed in step (a) to a heat treatment at a temperature in the range of 80-150° C. in the presence of a solvent to convert said at least a portion of the imide precursor into an imide, thereby forming said imide composition, said imide composition comprising said imide, the imide precursor formed in step (a) and three additional imide precursors formed in step (b), The dianhydride is selected from the group consisting of pyromellitic dianhydride, perylenetetracarboxylic dianhydride, naphthalenetetracarboxylic dianhydride, ethylene dianhydride, naphthalene dianhydride, phenanthrene dianhydride, anthracene dianhydride and p-benzoquinonetetracarboxylic dianhydride, The diamine is selected from the group consisting of dodecanediamine, decanediamine, ethylenediamine, butanediamine, dioctane diamine, methyldiamine and hexamethylenediamine.

2. The imide composition according to claim 1, characterized in that The dianhydride is pyromellitic dianhydride.

3. The imide composition according to claim 2, characterized in that The imide precursor formed in step (a) has the following general formula (I), 4. The imide composition according to claim 2, characterized in that The imide formed in step (b) has the following general formula (II), (II) 5. The imide composition according to claim 2, characterized in that: The three additional imide precursors formed in step (b) have the following general formulae (III), (IV) and (V), (III) (IV) (V) 6. The imide composition according to claim 1, characterized in that The diamine is hexamethylenediamine.

7. The imide composition according to any one of claims 1 to 6, characterized in that The dianhydride is pyromellitic dianhydride, and the diamine is hexamethylenediamine.

8. The imide composition according to any one of claims 1 to 6, characterized in that In step (a), the molar ratio of the dianhydride (A) to the diamine (B) is in the range of 0.33-1 (A / B).

9. The imide composition according to any one of claims 1 to 6, characterized in that The temperature in step (a) is in the range of 40-60°C.

10. The imide composition according to any one of claims 1 to 6, characterized in that The temperature in step (b) is in the range of 110-130°C.

11. A preservative composition comprising the imide composition according to any one of claims 1 to 10.

12. The preservative composition according to claim 11, characterized in that The preservative composition is an anti-rust preservative composition or an anti-corrosion preservative composition.

13. A metal product having a coating thereon, wherein the coating comprises the imide composition according to any one of claims 1 to 10 or the anticorrosive composition according to claim 11 or 12.

14. A method for preparing an imide composition, the method comprising the following steps: (a) reacting a dianhydride with a diamine in the presence of a solvent at a temperature in the range of 20-80° C., wherein the molar ratio of the dianhydride (A) to the diamine (B) is in the range of 0.25-4 (A / B), thereby forming an imide precursor; and (b) subjecting at least a portion of the imide precursor as formed in step (a) to a heat treatment at a temperature in the range of 80-150° C. in the presence of a solvent to convert said at least a portion of the imide precursor into an imide, thereby forming said imide composition, said imide composition comprising said imide, the imide precursor formed in step (a) and three additional imide precursors formed in step (b), The dianhydride is selected from the group consisting of pyromellitic dianhydride, perylenetetracarboxylic dianhydride, naphthalenetetracarboxylic dianhydride, ethylene dianhydride, naphthalene dianhydride, phenanthrene dianhydride, anthracene dianhydride and p-benzoquinonetetracarboxylic dianhydride, The diamine is selected from the group consisting of dodecanediamine, decanediamine, ethylenediamine, butanediamine, dioctane diamine, methyldiamine and hexamethylenediamine.

15. Use of the imide composition according to any one of claims 1 to 10 for preventing and / or reducing false brinelling in rolling bearing systems.

16. Use of the anticorrosive composition according to claim 11 or 12 for preventing and / or reducing false brinelling in rolling bearing systems.

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