Polyether amide lubricant, synthesis method and application of polyether amide lubricant in metal working fluid

Abstract

The invention relates to the technical field of metal working fluids, in particular to a polyether amide lubricant, a synthesis method and application of the polyether amide lubricant in the metal working fluids, the synthesis method of the polyether amide lubricant comprises the following steps: carrying out dehydration condensation reaction on dimer acid and polyether amine under the action of a catalyst to obtain a product 1; adding diethylenetriamine into the product 1 for reaction to obtain a product 2; dehydrating the product 2, adding ethylene oxide, and carrying out an alkoxylation reaction to obtain a product 3; and dehydrating the product 3, and carrying out an alkoxylation reaction on the dehydrated product 3 and epoxypropane under the action of a catalyst to obtain the polyether amide lubricant. The prepared polyether amide lubricant is added into a metal working fluid, and the prepared metal working fluid has good lubricity, hydrolysis resistance, defoaming performance, hard water resistance and anti-rust performance.

Description

Technical Field

[0001] This application relates to the field of metalworking fluid technology, and in particular to a polyetheramide lubricant, its synthesis method, and its application in metalworking fluids. Background Technology

[0002] With increasingly stringent environmental regulations and the deepening of the concept of sustainable development, the water-based transformation of metalworking fluids has become an irreversible trend. Among them, fully synthetic metalworking fluids have attracted much attention due to their excellent cooling properties, stability, and antibacterial properties. Currently, mainstream fully synthetic systems mainly rely on the combination of polyethers and fatty acids (such as neodecanoic acid). The "reverse solubility" of polyethers (i.e., precipitation from water after exceeding the cloud point) is utilized to form a lubricating film in the high-temperature zone where the tool and workpiece come into contact, and the fatty acids provide extreme pressure lubrication.

[0003] However, this system has inherent performance bottlenecks: insufficient lubrication performance; the oily lubricating film provided by fatty acids has limited strength, resulting in a significant gap in its overall lubrication performance, especially under harsh conditions such as heavy load, low-speed tapping, and broaching, compared with semi-synthetic liquids or pure oil systems containing a large amount of oil phase; the fundamental reason is that the lubrication characteristics of fatty acids and the cloud point precipitation characteristics of polyethers are independent of each other at the molecular level, and fail to achieve synergistic effect.

[0004] To overcome the aforementioned shortcomings, existing technologies have attempted to introduce polyether esters as a key lubricating component. The polyether ester molecule contains both polyether segments and ester aliphatic chains, theoretically allowing for the organic integration of the reverse dissolution properties of polyethers with the excellent boundary lubrication performance of ester groups into a single molecule. However, this technology has revealed a fatal flaw in industrial applications: the ester bonds are highly susceptible to hydrolysis in the inherently alkaline or amine-like working environment of metalworking fluids.

[0005] Hydrolysis leads to two serious consequences: (1) Free fatty acids are generated, which react with the alkali reserve (amine) in the system to form "soap". This process is called "soap precipitation". The precipitation of soap will destroy the stability of the system, causing the liquid to become turbid and separate into layers, and clogging the filter and the liquid supply line.

[0006] (2) The ester bond breaks, causing the polyether ester molecule to degrade and lose its designed synergistic lubrication function, ultimately resulting in a sharp decline in lubrication performance.

[0007] Therefore, although polyether esters provide an inspiring direction for molecular design, their chemical structural instability, namely their inability to resist hydrolysis and the resulting soap precipitation problem, severely restricts their application and promotion in actual production.

[0008] Therefore, how to prepare a lubricant that can be applied to metalworking fluids, which can inherit the design essence of "intramolecular synergistic lubrication" of polyether esters, fundamentally solve its chemical stability problem in alkaline / amine aqueous solutions, and at the same time make the prepared metalworking fluid have good defoaming properties, hard water resistance and rust prevention properties, has become an urgent problem to be solved. Summary of the Invention

[0009] To address the shortcomings of existing technologies, this application provides a polyether amide lubricant, a synthesis method, and its application in metalworking fluids, effectively solving the problems of easy hydrolysis, soap precipitation, and performance degradation in metalworking fluids synthesized from existing polyether ester lubricants in alkaline or amine environments.

[0010] The technical solution of this application is as follows: a stable amide bond is used to replace the easily hydrolyzed ester bond. First, a carboxyl-terminated amide oligomer is formed by the condensation of a dimer acid with a polyetheramine. Then, it is reacted with diethylenetriamine to construct a highly functional amino initiator. Finally, a polyether amide alkoxylated product with a specific structure (i.e., a polyether amide lubricant) is synthesized by two-step block alkoxylation with ethylene oxide and then with propylene oxide.

[0011] This application relates to a reverse polyether molecule design based on a hexafunctional hyperbranched initiator. The initiator is generated by an amidation reaction between polyether amine D230 and a dimer acid to produce an intermediate with D230 at the center and dimer acid at the ends. This intermediate then reacts with diethylenetriamine to form a "diethylenetriamine-dimer acid-D230-dimer acid-diethylenetriamine" structure with six amine hydrogen active sites and a molecular weight of approximately 1494. In this molecule, amphiphilic D230 forms the core, and ethylene oxide (EO) and propylene oxide (PO) are grafted sequentially in a reverse addition sequence, forming a star-shaped hyperbranched configuration where each branch exhibits a "PO-EO-lipophilic amide segment-D230" structure. This structure encapsulates the lipophilic segments with the surrounding amphiphilic D230 and hydrophilic EO segments, inhibiting their migration to the interface or the formation of micelles, thereby significantly reducing the system's foaming tendency. During the cutting process, frictional heat brings the polyether close to its cloud point, weakening the hydrogen bonding of the amphiphilic segments and causing a conformational change in the molecules. The oleophilic amide segments are exposed and adsorbed onto the metal surface. At the same time, the PO segments work with D230 to form an oil droplet-like precipitation structure, thus simultaneously achieving the dual functions of boundary lubrication and precipitation lubrication, combining low foaming and high-efficiency lubrication characteristics.

[0012] In a first aspect, this application provides a method for synthesizing polyetheramide lubricants, employing the following technical solution: A method for synthesizing a polyether amide lubricant, the method comprising the following steps: (1) Dimer acid and polyetheramine were subjected to dehydration condensation reaction under the action of a catalyst to obtain product 1; (2) Add diethylenetriamine to product 1 to react and obtain product 2; (3) After dehydrating product 2, ethylene oxide is added to carry out alkoxylation reaction to obtain product 3; (4) After dehydrating product 3, it undergoes alkoxylation reaction with propylene oxide under the action of a catalyst to obtain polyether amide lubricant.

[0013] By adopting the above technical solution, this application uses amide bonds to replace the unstable ester bonds in traditional polyether ester molecules as the linking group, thereby constructing a polyether amide with excellent chemical stability as a key lubricating component, thus effectively improving the lubrication performance of metalworking fluids.

[0014] Unlike chemically reactive ester bonds, the amide bonds used in this application have higher bond energies and stronger resistance to nucleophilic attacks. They also exhibit good stability in alkaline aqueous solutions, which significantly reduces the risk of hydrolysis from the source.

[0015] This application employs a two-step synthesis of the initiator: a reaction of a dimer acid with a polyetheramine, followed by end-capping with diethylenetriamine, yielding an amino-terminated initiator with an effective functionality of 6. This initiator contains organic amine components essential for pH adjustment and rust prevention. These amine molecules can form intermolecular interactions with amide bonds in the system, to a certain extent inhibiting the possible hydrolysis of amide bonds, thus creating a dynamic and stable chemical environment within the formulation. Simultaneously, the long dimer acid chain in the amino-terminated initiator molecule provides excellent oiliness and boundary lubrication, while the ethylene oxide / propylene oxide block polyether chain provides lubrication through a cloud point precipitation mechanism. The synergistic effect of these two components yields a lubricating polyetheramide lubricant. Applying this polyetheramide lubricant to metalworking fluids effectively improves the lubricity of the metalworking fluid.

[0016] In this application, a two-step synthesis of the initiator is employed: the reaction of dimer acid with polyetheramine and then end-capping with diethylenetriamine to obtain an amino-terminated initiator with an effective functionality of 6, thereby effectively improving the defoaming performance of the metalworking fluid.

[0017] Preferably, in step (1), the temperature of the dehydration condensation reaction is 140-180℃; for example, 140℃, 141℃, 142℃, 143℃, 144℃, 145℃, 146℃, 147℃, 148℃, 149℃, 150℃, 151℃, 152℃, 153℃, 154℃, 155℃, 156℃, 157℃, 158℃, 159℃, 160℃, 161℃, 162℃, 163℃, 164℃, 165℃, 166℃, 167℃, 168℃, 169℃, 170℃, 171℃, 172℃, 173℃, 174℃, 175℃, 176℃, 177℃, 178℃, 179℃ or 180℃.

[0018] Preferably, in step (1), the reaction time is 5-9 hours; for example, the reaction time is 5, 6, 7, 8 or 9 hours.

[0019] Preferably, in step (1), product 1 is a carboxyl-terminated liquid with an acid value of 85±5mg KOH / g and an amine value of ≤5mg KOH / g.

[0020] Preferably, in step (2), the reaction temperature is 140-180℃; for example, 140℃, 141℃, 142℃, 143℃, 144℃, 145℃, 146℃, 147℃, 148℃, 149℃, 150℃, 151℃, 152℃, 153℃, 154℃, 155℃, 156℃, 157℃, 158℃, 159℃, 160℃, 161℃, 162℃, 163℃, 164℃, 165℃, 166℃, 167℃, 168℃, 169℃, 170℃, 171℃, 172℃, 173℃, 174℃, 175℃, 176℃, 177℃, 178℃, 179℃ or 180℃.

[0021] Preferably, in step (2), the reaction time is 5-9 hours; for example, the reaction time is 5, 6, 7, 8 or 9 hours.

[0022] Preferably, in step (2), product 2 is an amino-terminated initiator with an amine value of 150±15mg KOH / g and an acid value of ≤5mg KOH / g; the effective active hydrogen functionality of the initiator is 6, and the number of amino groups is 4 (2 primary amines and 1 secondary amine).

[0023] Preferably, in step (3), the temperature of the alkoxylation reaction is 85-115℃; for example, 85℃, 86℃, 87℃, 88℃, 89℃, 90℃, 91℃, 92℃, 93℃, 94℃, 95℃, 96℃, 97℃, 98℃, 99℃, 100℃, 101℃, 102℃, 103℃, 104℃, 105℃, 106℃, 107℃, 108℃, 109℃, 110℃, 111℃, 112℃, 113℃, 114℃ or 115℃.

[0024] Preferably, in step (4), the temperature of the alkoxylation reaction is 125-145℃; for example, 125℃, 126℃, 127℃, 128℃, 129℃, 130℃, 131℃, 132℃, 133℃, 134℃, 135℃, 136℃, 137℃, 138℃, 139℃, 140℃, 141℃, 142℃, 143℃, 144℃ or 145℃.

[0025] Preferably, in step (1), the catalyst is 4-dimethylaminopyridine.

[0026] Preferably, in step (4), the catalyst is at least one of sodium methoxide, potassium hydroxide, and barium hydroxide; more preferably, the catalyst is potassium hydroxide.

[0027] Preferably, in step (1), the molar ratio of dimer acid to polyetheramine is (1.8-2.2):1; for example, 1.8:1, 1.9:1, 2:1, 2.1:1 or 2.2:1.

[0028] Preferably, in step (1), the amount of catalyst added is 0.1%-0.3% of the total amount of dimer acid and polyetheramine added; Preferably, in step (2), the molar ratio of product 1 to diethylenetriamine is 1:(2-2.4); for example, 1:2, 1:2.1, 1:2.2, 1:2.3 or 1:2.4.

[0029] Preferably, the molar ratio of product 2 to ethylene oxide in step (3) is 0.1:(6-12); for example, 0.1:6, 0.1:7, 0.1:8, 0.1:9, 0.1:10, 0.1:11 or 0.1:12.

[0030] Preferably, the molar ratio of product 3 to propylene oxide in step (4) is 0.1:(6-12); for example, 0.1:6, 0.1:7, 0.1:8, 0.1:9, 0.1:10, 0.1:11 or 0.1:12.

[0031] Preferably, the amount of catalyst added in step (4) is 0.1-0.3% of the total amount of product 3 and propylene oxide.

[0032] Secondly, this application provides a polyetheramide lubricant, which adopts the following technical solution: A polyetheramide lubricant synthesized using the above method.

[0033] Thirdly, this application provides the application of the above-mentioned polyether amide lubricants in metalworking fluids, using the following technical solution: An application of the above-mentioned polyether amide lubricant in metalworking fluids.

[0034] Preferably, the amount of the polyether amide lubricant added is 1%-20% of the mass of the metalworking fluid.

[0035] By adopting the above technical solution, the present application uses a hydrophobic core composed of repeating units of "dimer acid-polyetheramine-dimer acid" connected by amide bonds, and a hydrophilic-lipophilic block polyether structure initiated by the hydrophobic core and first passed through ethylene oxide segments and then through propylene oxide segments, which is a polyether amide lubricant.

[0036] The polyether amide lubricant was added to the metalworking fluid at a mass percentage of 1%-20%. The resulting metalworking fluid exhibited good hydrolysis resistance, defoaming properties, thermal stability, long-term wear resistance, hard water resistance, and rust prevention.

[0037] Fourthly, this application provides a metalworking fluid, which adopts the following technical solution: A metalworking fluid, comprising the following components by weight: Tricarboxylic acids 2-8%; Benzotriazole 0.5-1.5%; Sebacic acid 1-3%; Triethanolamine 10-20%; The polyether amide lubricant prepared above accounts for 1%-20%; The rest is water.

[0038] In summary, this application includes at least one of the following beneficial technical effects: 1. This application discloses a polyether amide lubricant, a synthesis method, and its application in metalworking fluids. This application creatively prepares a novel polymer that combines aliphatic chain lubrication and polyether reverse-solubility lubrication, linked by stable amide bonds, through a synthetic route of "amidation-multifunctional initiator construction-two-step block alkoxylation," which is a polyether amide lubricant. Applying the polyether amide lubricant to metalworking fluids effectively improves the lubricity and stability of the metalworking fluids. 2. When the polyether amide lubricant prepared in this application is applied to metalworking fluid, the amide bond in the core of the polyether amide lubricant effectively resists hydrolysis in the alkaline / amine environment of the metalworking fluid. The amine component in the system can further inhibit hydrolysis, effectively solving the problems of soap precipitation and degradation of traditional polyether esters. Applying polyether amide lubricant to metalworking fluid effectively improves the hydrolysis resistance of the metalworking fluid. 3. The polyether amide lubricant prepared in this application is added to the metalworking fluid, and the prepared metalworking fluid has good defoaming properties, thermal stability, long-term wear performance, hard water resistance and rust prevention properties. 4. The present application discloses a method for synthesizing polyether amide lubricants. The method has clear steps, mild conditions, and is easy to implement for industrial production. Attached Figure Description

[0039] Figure 1 The images show the wear scars obtained from the long-die test of the metalworking fluid prepared in Example 1. Figure 2 The image shows the wear scars obtained from the long-die test of the metalworking fluid prepared in Example 2. Figure 3 The image shows the wear scars obtained from the long-die test of the metalworking fluid prepared in Example 3. Figure 4 The image shows the wear scars obtained from the long-die test of the metalworking fluid prepared in Example 4. Figure 5 The image shows the wear scars obtained from the long-die test of the metalworking fluid prepared using Comparative Example 1. Figure 6 The image shows the wear scars obtained from the long-die test of the metalworking fluid prepared using Comparative Example 2. Figure 7 The image shows the corrosion resistance test results of the metalworking fluid prepared in Example 1. Figure 8 The image shows the corrosion resistance test results of the metalworking fluid prepared in Example 2. Figure 9 The image shows the corrosion resistance test results of the metalworking fluid prepared in Example 3. Figure 10 The image shows the corrosion resistance test results of the metalworking fluid prepared in Example 4. Figure 11 The image shows the corrosion resistance test results of the metalworking fluid prepared using Comparative Example 1. Figure 12 The image shows the corrosion resistance test results of the metalworking fluid prepared using Comparative Example 2. Detailed Implementation

[0040] The technical solutions of this application are further illustrated by specific embodiments below. These specific embodiments do not represent a limitation on the scope of protection of this application. Any non-essential modifications and adjustments made by others based on the concept of this application still fall within the scope of protection of this application.

[0041] All raw materials involved in this application are commercially available products, among which, Raw materials used in the formulation of metalworking fluids: Tricarboxylic acid, purchased from BASF IRGACORL190PLUS; Benzotriazole (BTA) was purchased from Chuzhou Kanghua Electronic Materials Co., Ltd. Sebacic acid, purchased from Shandong Kaisai Biomaterials Co., Ltd.; Triethanolamine, purchased from BASF Yangtze. Neodecanoic acid, purchased from Mobil; Polyether 1740, purchased from BASF; Polyether 1720, purchased from BASF.

[0042] The present application will be further described in detail below with reference to embodiments and comparative examples.

[0043] A method for synthesizing a polyether amide lubricant includes the following steps: Step 1: Synthesis of carboxyl-terminated amide oligomers: Using dimer acid and polyetheramine (D230) as raw materials, a dehydration condensation reaction was carried out at 140-180℃ under nitrogen conditions for 5-9 hours in the presence of catalyst 4-dimethylaminopyridine to obtain a carboxyl-terminated liquid with an acid value of 85±5mg KOH / g and an amine value of ≤5mg KOH / g (i.e., product 1). The molar ratio of dimer acid to polyetheramine (D230) is (1.8-2.2):1; the amount of catalyst added is 0.1%-0.3% of the total amount of dimer acid and polyetheramine (D230).

[0044] Step 2: Synthesis of amino-terminated multifunctional initiators: Diethylenetriamine was added to product 1 obtained in step one, and the reaction was continued for 5-9 hours at 140-180℃ under nitrogen conditions to obtain an amino-terminated initiator (i.e., product 2) with an amine value of 150±15mg KOH / g and an acid value of ≤5mg KOH / g. The effective active hydrogen functionality of the initiator is 6, and the number of amino groups is 4 (2 primary amines and 1 secondary amine).

[0045] The molar ratio of product 1 to diethylenetriamine is 1:(2-2.4).

[0046] Step 3: Synthesis of all-ethylene oxide (EO) first-order polyether: After the initiator obtained in step 2 (i.e. product 2) was dehydrated under vacuum for 0.5 hours, ethylene oxide was introduced at 85-115℃ and atmospheric pressure (1 atmosphere) to carry out an alkoxylation reaction until the pressure no longer changed, and all-EO first-order polyether (i.e. product 3) was obtained. The molar ratio of product 2 to ethylene oxide is 0.1:(6-12).

[0047] Step 4: Synthesis of propylene oxide (PO) block diethylene ether: After dehydrating the all-EO first-order polyether (i.e., product 3) obtained in step 3 under vacuum for 0.5 hours, potassium hydroxide was added as a catalyst, and propylene oxide was introduced at 125-145℃ and normal pressure to carry out an alkoxylation reaction until the pressure no longer changed, thus obtaining a polyether amide lubricant.

[0048] The molar ratio of product 3 to propylene oxide is 0.1:(6-12). The amount of catalyst added is 0.1-0.3% of the total amount of product 3 and propylene oxide.

[0049] Example 1:

[0050] A method for synthesizing a polyether amide lubricant, comprising the following steps: Step 1: Synthesis of carboxyl-terminated amide oligomers Using 2 mol of dimer acid and 1 mol of polyetheramine D230 as raw materials, a dehydration condensation reaction was carried out at 160 °C under nitrogen conditions for 5 hours in the presence of 0.0223 mol of 4-dimethylaminopyridine catalyst to obtain a viscous liquid with carboxyl-terminated end groups (i.e., product 1) with an acid value of 85±5 mg KOH / g and an amine value of ≤5 mg KOH / g.

[0051] Step 2: Synthesis of amino-terminated multifunctional initiators Add 2 mol of diethylenetriamine to 1 mol of product 1, and continue the reaction at 160℃ under nitrogen for 5 hours to obtain an amino-terminated initiator (i.e., product 2) with an amine value of 150±15 mg KOH / g and an acid value of ≤5 mg KOH / g. The effective active hydrogen functionality of this initiator is 6, and the number of amino groups is 4 (2 primary amines and 1 secondary amine).

[0052] Step 3: Synthesis of all-EO first-order polyether Take 0.1 mol of the initiator obtained in step 2 and place it in a high-pressure reactor for vacuum dehydration for 0.5 hours. After dehydration, 6 mol of ethylene oxide is introduced at 100°C and atmospheric pressure (1 atmosphere). After the feeding is completed, age the product at 100°C until the pressure in the reactor no longer decreases, indicating that the reaction is complete. Cool the product to 60°C and discharge it to obtain the all-EO first-stage polyether (i.e., product 3).

[0053] Step 4: Synthesis of PO block di-polyether 0.1 mol of the first-order polyether obtained in step three was placed in a high-pressure reactor and dehydrated under vacuum for 0.5 hours. After dehydration, 0.019 mol of potassium hydroxide was added as a catalyst. Subsequently, 6 mol of propylene oxide was introduced at 135°C and atmospheric pressure. After the feeding was completed, the mixture was aged at 135°C until the reactor pressure remained constant. The mixture was then cooled to 60°C and discharged to obtain a polyether amide lubricant with a molecular weight of 7614 g / mol. This product exhibits relatively hydrophilic properties.

[0054] Example 2:

[0055] A method for synthesizing a polyether amide lubricant, comprising the following steps: Step 1: Synthesis of carboxyl-terminated amide oligomers Using 2 mol of dimer acid and 1 mol of polyetheramine D230 as raw materials, a dehydration condensation reaction was carried out at 160 °C under nitrogen conditions for 5 hours in the presence of 0.0223 mol of 4-dimethylaminopyridine catalyst to obtain a viscous liquid with carboxyl-terminated end groups (i.e., product 1) with an acid value of 85±5 mg KOH / g and an amine value of ≤5 mg KOH / g.

[0056] Step 2: Synthesis of amino-terminated multifunctional initiators Add 2 mol of diethylenetriamine to 1 mol of product 1, and continue the reaction at 160℃ under nitrogen for 5 hours to obtain an amino-terminated initiator (i.e., product 2) with an amine value of 150±15 mg KOH / g and an acid value of ≤5 mg KOH / g. The effective active hydrogen functionality of this initiator is 6, and the number of amino groups is 4 (2 primary amines and 1 secondary amine).

[0057] Step 3: Synthesis of all-EO first-order polyether Take 0.1 mol of the initiator obtained in step 2 and place it in a high-pressure reactor for vacuum dehydration for 0.5 hours. After dehydration, 6 mol of ethylene oxide is introduced at 100°C and atmospheric pressure (1 atmosphere). After the feeding is completed, age the product at 100°C until the pressure in the reactor no longer decreases, indicating that the reaction is complete. Cool the product to 60°C and discharge it to obtain the all-EO first-stage polyether (i.e., product 3).

[0058] Step 4: Synthesis of PO block di-polyether 0.1 mol of the first-order polyether obtained in step three was placed in a high-pressure reactor and dehydrated under vacuum for 0.5 hours. After dehydration, 0.0396 mol of potassium hydroxide was added as a catalyst. Subsequently, 12 mol of propylene oxide was introduced at 135°C and atmospheric pressure. After the feeding was completed, the mixture was aged at 135°C until the reactor pressure remained constant. The mixture was then cooled to 60°C and discharged to obtain a polyether amide lubricant with a molecular weight of 11094 g / mol. This product exhibits stronger hydrophobicity and more significant reverse dissolution precipitation characteristics, making it suitable for processing conditions requiring thick lubricating films.

[0059] Example 3:

[0060] A method for synthesizing a polyether amide lubricant, comprising the following steps: Step 1: Synthesis of carboxyl-terminated amide oligomers Using 2 mol of dimer acid and 1 mol of polyetheramine D230 as raw materials, a dehydration condensation reaction was carried out at 160 °C under nitrogen conditions for 5 hours in the presence of 0.0223 mol of 4-dimethylaminopyridine catalyst to obtain a viscous liquid with carboxyl-terminated end groups (i.e., product 1) with an acid value of 85±5 mg KOH / g and an amine value of ≤5 mg KOH / g.

[0061] Step 2: Synthesis of amino-terminated multifunctional initiators Add 2 mol of diethylenetriamine to 1 mol of product 1, and continue the reaction at 160℃ under nitrogen for 5 hours to obtain an amino-terminated initiator (i.e., product 2) with an amine value of 150±15 mg KOH / g and an acid value of ≤5 mg KOH / g. The effective active hydrogen functionality of this initiator is 6, and the number of amino groups is 4 (2 primary amines and 1 secondary amine).

[0062] Step 3: Synthesis of all-EO first-order polyether Take 0.1 mol of the initiator obtained in step 2 and place it in a high-pressure reactor for vacuum dehydration for 0.5 hours. After dehydration, 12 mol of ethylene oxide is introduced at 100°C and atmospheric pressure (1 atmosphere). After the feeding is completed, age the product at 100°C until the pressure in the reactor no longer decreases, indicating that the reaction is complete. Cool the product to 60°C and discharge it to obtain the all-EO first-stage polyether (i.e., product 3).

[0063] Step 4: Synthesis of PO block di-polyether 0.1 mol of the first-order polyether obtained in step three was placed in a high-pressure reactor and dehydrated under vacuum for 0.5 hours. After dehydration, 0.0491 mol of potassium hydroxide was added as a catalyst. Subsequently, 12 mol of propylene oxide was introduced at 135°C and atmospheric pressure. After the feeding was completed, the mixture was aged at 135°C until the reactor pressure remained constant. The mixture was then cooled to 60°C and discharged to obtain a polyether amide lubricant with a molecular weight of 13734 g / mol. This product has the highest molecular weight and combines good water solubility with excellent lubricity due to its long PO chain.

[0064] Example 4:

[0065] A method for synthesizing a polyether amide lubricant, comprising the following steps: Step 1: Synthesis of carboxyl-terminated amide oligomers Using 2 mol of dimer acid and 1 mol of polyetheramine D230 as raw materials, a dehydration condensation reaction was carried out at 160 °C under nitrogen conditions for 5 hours in the presence of 0.0223 mol of 4-dimethylaminopyridine catalyst to obtain a viscous liquid with carboxyl-terminated end groups (i.e., product 1) with an acid value of 85±5 mg KOH / g and an amine value of ≤5 mg KOH / g.

[0066] Step 2: Synthesis of amino-terminated multifunctional initiators Add 2 mol of diethylenetriamine to 1 mol of product 1, and continue the reaction at 160℃ under nitrogen for 5 hours to obtain an amino-terminated initiator (i.e., product 2) with an amine value of 150±15 mg KOH / g and an acid value of ≤5 mg KOH / g. The effective active hydrogen functionality of this initiator is 6, and the number of amino groups is 4 (2 primary amines and 1 secondary amine).

[0067] Step 3: Synthesis of all-EO first-order polyether Take 0.1 mol of the initiator obtained in step 2 and place it in a high-pressure reactor for vacuum dehydration for 0.5 hours. After dehydration, 12 mol of ethylene oxide is introduced at 100°C and atmospheric pressure (1 atmosphere). After the feeding is complete, age at 100°C until the pressure in the reactor no longer decreases, indicating that the reaction is complete. Cool down to 60°C and discharge to obtain the all-EO first-stage polyether (i.e., product 3).

[0068] Step 4: Synthesis of PO block di-polyether Take 0.1 mol of the first-order polyether obtained in step three and place it in a high-pressure reactor. Dehydrate it under vacuum for 0.5 hours. After dehydration, add 0.0366 mol of potassium hydroxide as a catalyst. Then, at 135°C and atmospheric pressure, introduce 6 mol of propylene oxide. After the feed is complete, age it at 135°C until the reactor pressure remains constant. Cool it down to 60°C and discharge it to obtain a polyether amide lubricant with a molecular weight of 10254 g / mol. This product has excellent water solubility at room temperature, and the PO block ensures the lubrication ability of cloud point precipitation in the high-temperature friction zone.

[0069] Application performance testing: The polyether amide lubricant prepared in the above embodiments was added to the metalworking fluid in the following proportions to prepare the metalworking fluid, as shown in Table 1.

[0070] Table 1 Formulation of Metalworking Fluids

[0071] The solubility, defoaming performance, thermal stability, long-term wear resistance, hard water resistance, and rust prevention performance of the metalworking fluids prepared according to the formulations of the above embodiments, the metalworking fluid of Comparative Example 1, and the metalworking fluid of Comparative Example 2 were tested. The test results are as follows: 1. Foam testing method: Testing instrument: Guangdong Platinum Metalworking Fluid Stability Tester, model: BSV-11; Test method: (1) Dilute the metalworking fluid with tap water (water hardness 125ppm) at a ratio of 5% and pour it into a 100ml stoppered graduated cylinder; (2) Shake the stoppered graduated cylinder up and down 60 times at a frequency of 120 times / min, and record the foam height and defoaming time after standing.

[0072] 2. Thermal stability test method: Place the sample to be tested in a 50℃ constant temperature chamber and let it stand for 48 hours. Observe whether there is precipitation, sedimentation, or turbidity. The result is judged as follows: no precipitation, sedimentation, or turbidity is qualified.

[0073] Table 2 Defoaming and thermal stability test results

[0074] As shown in Table 2, the metalworking fluid prepared using the polyether amide lubricants prepared by the methods in Examples 1-4 exhibits good defoaming properties and thermal stability, indicating that the prepared metalworking fluid has good defoaming properties and hydrolysis resistance.

[0075] The polyether amide lubricant prepared in Example 1 was added to the metalworking fluid. Although the metalworking fluid prepared had poor clarity and fluorescence, it did not affect its defoaming performance or thermal stability, and the prepared metalworking fluid did not affect its use.

[0076] Based on Example 2 and Comparative Example 1, it can be seen that the metalworking fluid prepared using a commercially available lubricant (i.e., polyether ester) in Comparative Example 1 has poorer defoaming performance and thermal storage stability than the metalworking fluid prepared in Example 2. This indicates that the metalworking fluid prepared using the lubricant of this application has good defoaming performance, solubility, and hydrolysis resistance.

[0077] 3. Long-term wear test method Testing instrument: Xiamen Tianji MS-10A four-ball friction testing machine; Test conditions: Motor speed: 1200 rpm, initial temperature: 40℃, pressure rating: 40Kg; grinding time: 30min; Dilution ratio: 5% tap water; Test method: (1) Turn on the four-ball friction tester to preheat and set the parameters; (2) Set the long grinding parameters, refer to standard GB / T3142; (3) Add the corresponding weights according to the test level; (4) Put three steel balls in the oil cup and one steel ball in the main shaft and tighten them; (5) Pour the oil sample to be tested into the oil cup, the liquid level is consistent with the scale line on the inner wall of the oil cup, about 15mL; (6) Put the oil cup with the oil sample into the main shaft, put down the lever arm, add the weights, and put down the main shaft oil cup retaining ring; (7) Turn on the motor switch and start the test. After the test is completed, first turn off the motor switch, then record the friction curve and the wear scar diameter, summarize the data and draw a conclusion.

[0078] Table 3 Results of long-term wear resistance test

[0079] As shown in Table 3, when the polyether amide lubricants prepared in Examples 1-4 of this application are added to the metalworking fluid, the resulting metalworking fluid exhibits good long-term wear resistance, indicating that the prepared metalworking fluid has good lubricity.

[0080] As can be seen from Example 2 and Comparative Example 1, the metalworking fluid prepared using a commercially available lubricant (i.e., polyether ester) in Comparative Example 1 has poorer long-running properties than the metalworking fluid prepared in Example 2, indicating that the metalworking fluid prepared using the lubricant of this application has good lubricity.

[0081] Based on the test results of Example 2 and Comparative Example 2, it can be seen that the long-term wear test results of Example 2 are better than those of Comparative Example 2. This indicates that compared with the metalworking fluid prepared by polyether and neodecanoic acid, the polyether amide lubricant prepared by the initiator (amino precursor, i.e. product 2) of this application is used to prepare the metalworking fluid, which effectively improves the lubricity of the product.

[0082] 4. Resistance to hard water Dilute the mother liquor of the metalworking fluid sample with 500 / 800 / 1000 / 1500 ppm of calcium and magnesium ion-treated hard water at a concentration of 5%, respectively. After stirring thoroughly, pour the solution into a 100 ml stoppered graduated cylinder and let it stand for 24 hours. Observe the oil / soap precipitation on the surface. Judgment: The liquid is uniform and stable, and there is no oil or soap precipitation on the surface, indicating that it is qualified.

[0083] Table 4 Results of Hard Water Resistance Test

[0084] As shown in Table 4, the polyether amide lubricants prepared in Examples 1-4 of this application, when added to metalworking fluids, produce metalworking fluids with good resistance to hard water.

[0085] Based on Example 2 and Comparative Example 1, it can be seen that the metalworking fluid prepared using a commercially available lubricant (i.e., polyether ester) in Comparative Example 1 has poor hard water resistance compared to the metalworking fluid prepared in Example 2. This indicates that the metalworking fluid prepared using the lubricant of this application has good hard water resistance.

[0086] 5. Iron filings corrosion resistance test: Test method: Dilute the metalworking fluid sample with tap water at a ratio of 5% (water hardness 125ppm) and test it using the iron filings rust prevention test method (IP287); Result determination: No rust spots: Level 0, Several rust spots: Level 1, Ten or more rust spots: Level 2, Several dozen rust spots: Level 3, Severe corrosion: Level 4.

[0087] Table 5 Corrosion Resistance Test Results

[0088] As shown in Table 5, the polyether amide lubricants prepared in Examples 1-4 of this application, when added to metalworking fluids, produce metalworking fluids with good anti-corrosion properties.

[0089] As shown in Tables 2-5, when the polyether amide lubricant prepared in this application is added to the metalworking fluid, the resulting metalworking fluid exhibits good defoaming properties, thermal stability, long-term wear resistance (wear resistance), hard water resistance, and rust prevention. This indicates that applying the polyether amide lubricant prepared in this application to the metalworking fluid results in the metalworking fluid possessing good lubricity, defoaming properties, hard water resistance, rust prevention, and hydrolysis resistance.

[0090] As shown in Tables 2-5, when the polyether amide lubricant prepared in Example 1 is added to the metalworking fluid, the resulting metalworking fluid has poor clarity and fluorescence, but this does not affect its defoaming performance, thermal stability, long-term wear resistance (wear resistance), hard water resistance, and rust prevention performance. The resulting metalworking fluid does not affect its use.

Claims

1. A method for synthesizing a polyetheramide lubricant, characterized in that: The method includes the following steps: (1) Dimer acid and polyetheramine were subjected to dehydration condensation reaction under the action of a catalyst to obtain product 1; (2) Add diethylenetriamine to product 1 to react and obtain product 2; (3) After dehydrating product 2, ethylene oxide is added to carry out alkoxylation reaction to obtain product 3; (4) After dehydrating product 3, it undergoes alkoxylation reaction with propylene oxide under the action of a catalyst to obtain polyether amide lubricant.

2. The method for synthesizing a polyetheramide lubricant according to claim 1, characterized in that: In step (1), the temperature of the dehydration condensation reaction is 140-180℃ and the reaction time is 5-9 hours; product 1 is a carboxyl-terminated liquid with an acid value of 85±5mgKOH / g and an amine value of ≤5mgKOH / g.

3. The method for synthesizing a polyetheramide lubricant according to claim 1, characterized in that: In step (2), the reaction temperature is 140-180℃ and the reaction time is 5-9 hours; product 2 is an amino-terminated initiator with an amine value of 150±15mg KOH / g, an acid value of ≤5mg KOH / g, and an effective functionality of 6.

4. The method for synthesizing a polyetheramide lubricant according to claim 1, characterized in that: In step (3), the alkoxylation reaction temperature is 85-115℃; in step (4), the alkoxylation reaction temperature is 125-145℃.

5. The method for synthesizing a polyetheramide lubricant according to claim 1, characterized in that: In step (1), the catalyst is 4-dimethylaminopyridine; in step (4), the catalyst is at least one of sodium methoxide, potassium hydroxide, and barium hydroxide.

6. The method for synthesizing a polyetheramide lubricant according to claim 1, characterized in that: In step (1), the molar ratio of dimer acid to polyetheramine is (1.8-2.2):1; in step (1), the amount of catalyst added is 0.1%-0.3% of the total amount of dimer acid and polyetheramine added. In step (2), the molar ratio of product 1 to diethylenetriamine is 1:(2-2.4). In step (3), the molar ratio of product 2 to ethylene oxide is 0.1:(6-12). In step (4), the molar ratio of product 3 to propylene oxide is 0.1:(6-12). In step (4), the amount of catalyst added is 0.1-0.3% of the total amount of product 3 and propylene oxide added.

7. A polyetheramide lubricant synthesized using the method described in any one of claims 1-6.

8. The application of the polyether amide lubricant as described in claim 7 in metalworking fluids.

9. The application according to claim 8, characterized in that: The amount of the polyetheramide lubricant added is 1%-20% of the mass of the metalworking fluid.

10. A metalworking fluid, characterized in that: Includes the following mass fractions: Tricarboxylic acids 2-8%; Benzotriazole 0.5-1.5%; Sebacic acid 1-3%; Triethanolamine 10-20%; The polyetheramide lubricant of claim 7 is 1%-20%; The rest is water.

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