Heat treated quenchants and basic high molecular weight polymers thereof

Abstract

The present application discloses a quenching agent and its basic high molecular polymer after heat treatment, wherein the basic high molecular polymer has the following molecular formula: wherein n=1000-3000; m=1000-3000.

Description

Technical Field

[0001] This application relates to the field of metal heat treatment process media, and more particularly to a heat treatment quenching agent and its alkaline polymer. Background Technology

[0002] Quenching oil is a core cooling medium in metal heat treatment processes. Its cooling stability, workpiece brightness, and oxidation resistance directly determine the quality of heat treatment and production costs. Existing improvement technologies sometimes increase cooling speed by reducing oil viscosity or adding cooling accelerators, but neglect long-term stability.

[0003] Another set of solutions focuses on rust prevention or lifespan extension, but sacrifices the gloss of the workpiece. For example, rust inhibitors containing heavy metals can easily cause the surface to darken, and high doses of antioxidants can increase the viscosity of the oil phase and affect the gloss.

[0004] Chinese invention patent CN107557544A describes a quenching oil composition that achieves a brighter surface by adding a brightener and obtains excellent cooling performance by reducing the viscosity of the oil and enhancing its fluidity at low temperatures. This quenching oil is suitable for use at lower temperatures. However, due to the lack of high-temperature antioxidants in its composition, its antioxidant capacity is expected to be insufficient and it does not meet the requirements for long-term use at higher temperatures.

[0005] Chinese invention patent CN118957217A describes improving the thermal oxidation stability of quenching oil by using a self-made quenching base oil. It improves the brightness of the quenching oil by adding sodium phenolate polyoxyethylene ether, sodium thiazolinyl dithiopropane sulfonate, and fatty amine polyoxyethylene, and improves other properties such as cleaning and rust prevention by adding sodium pentadecyl sulfonate, polyisobutylene succinimide, and sodium petroleum sulfonate. However, its components are still slightly insufficient in terms of high-temperature oxidation resistance, and it lacks stable cooling rate performance. It is foreseeable that its long-term high-temperature oxidation resistance and cooling stability are insufficient and do not meet the requirements for long-term use.

[0006] Chinese invention patent CN111471842A describes a cold-rate stable, high-speed bright quenching oil, with the following composition: 78-90% base oil, 0.5-2% antioxidant, 0.1-0.5% auxiliary antioxidant, 5-8% high-temperature quenching agent, 0.5-2% low-temperature quenching agent, 1.5-5% brightener, 1-3% auxiliary dispersant, and 1-2% rust inhibitor; wherein the base oil has a saturated hydrocarbon content ≥95%, a viscosity index ≥110, and a flash point ≥170℃. It can be seen that this quenching oil is only suitable for low-temperature conditions and cannot be used under long-term high-temperature conditions.

[0007] Chinese invention patent CN119640001A describes a multi-purpose high-speed quenching oil, with the following components: 85-91 parts base oil, 5-7 parts refrigerant, 0.5-2.0 parts antioxidant, 3-5 parts dispersant, and 0.5-2.0 parts emulsifier. This design utilizes an emulsifier that promotes cooling at low temperatures, and the emulsifier and dispersant also facilitate cleaning of the workpiece in subsequent cleaning stages. While this quenching oil is designed for multiple uses, it lacks brightening additives, which suggests insufficient gloss on the finished workpiece. Furthermore, its stability in cooling rate and antioxidant properties at high temperatures are also insufficient, failing to meet the requirements for long-term use.

[0008] Due to the widespread defects in existing quenching oils during long-term use, although there have been improvements in one or more properties, they still fall short in terms of long-term effectiveness and multi-functionality (cooling, brightening, and oxidation resistance), making it impossible to simultaneously meet the stringent requirements of high-end manufacturing industries for quality stability and overall cost. In summary, existing quenching oils have at least the following defects:

[0009] (1) Unstable cooling performance; under high temperature and continuous use, traditional quenching oils cause oxidation and cracking of the base oil and additives, resulting in a significant decrease in cooling rate. This leads to workpieces having substandard hardness, inconsistent deformation, and increased scrap rate after quenching.

[0010] (2) Insufficient gloss and contamination of workpiece surface; The oil itself is not bright enough or after a period of use, the gum, asphalt and sludge produced by the oxidation of the oil will adhere to the workpiece surface, forming a sticky oil film or stain that is difficult to clean, which seriously affects the appearance of the workpiece and the quality of subsequent coating and assembly, and increases cleaning costs and environmental pressure.

[0011] (3) Not resistant to high temperatures and has a short service life: The oil itself has a short lifespan, especially under high temperature conditions. The oil oxidizes rapidly, and the oxidation process leads to increased viscosity, increased acid value, and sludge precipitation. This not only degrades the performance but also clogs the filtration system and contaminates the quenching tank. To maintain basic performance, it is necessary to frequently adjust the performance or replace it completely, resulting in high overall maintenance costs.

[0012] Therefore, developing a multifunctional quenching oil that balances cooling performance, long-term stability, excellent workpiece gloss, and long oxidation resistance has become a critical technical bottleneck that urgently needs to be overcome in this field. Summary of the Invention

[0013] This application provides a heat treatment quenching agent and its alkaline polymer. After 6000 hours of operation on an automated circulating equipment simulating continuous on-site production, the key parameters of the cooling curve (measured according to ISO 9950) remained within the allowable range of the process. No adjustments are required during long-term use, ensuring the performance stability of the workpiece after quenching. The workpiece surface exhibits excellent and lasting brightness: after quenching, the surface of the GCr15 bearing ring displays a uniform silver-gray to silver-white color, without any colored film or sticky residue.

[0014] Furthermore, the heat treatment quenching agent described in this application has excellent antioxidant properties and an ultra-long high-temperature service life: after 96 hours of SH / T 0219 thermal oxidation stability test, no sludge or sediment was detected, the viscosity ratio was <1.2, and the increase in residual carbon was <1.2%.

[0015] To address the above technical problems, this application provides an alkaline polymer with the following molecular formula:

[0016]

[0017] Where n = 1000~3000; m = 1000~3000.

[0018] According to another aspect of this application, a heat treatment quenching agent is also provided, the heat treatment quenching agent comprising the following substances by weight percentage:

[0019] As mentioned above, the alkaline polymer content is 0.9% to 7%;

[0020] Base oil 72-95%;

[0021] 2-10% refrigerant;

[0022] Antioxidant 2-8%;

[0023] Brightener 0.1-3%.

[0024] According to a preferred embodiment of this application, the base oil is implemented as a hydroisomerized base oil.

[0025] According to a preferred embodiment of this application, the cooling agent is selected from at least one of polyisobutylene polymers or systems compounded with sulfonates, oil-soluble polymers, and nonionic surfactants.

[0026] According to a preferred embodiment of this application, the antioxidant is implemented as a phenol or amine, a combination of phenols and amines, or a combination of sulfur / phosphorus antioxidants.

[0027] According to a preferred embodiment of this application, the brightening agent is implemented as an imidazoline derivative or an ester polymer.

[0028] According to another aspect of this application, this application also provides the use of the alkaline polymer as described above, characterized in that it is used in the preparation of a quenching agent for heat treatment. Detailed Implementation

[0029] The preferred embodiments described below are merely examples, and other obvious variations will be apparent to those skilled in the art. The basic principles of the invention defined in the following description can be applied to other embodiments, modifications, improvements, equivalents, and other technical solutions that do not depart from the spirit and scope of the invention.

[0030] The quenching agent for heat treatment according to a preferred embodiment of this application will be described in detail below, wherein the quenching agent for heat treatment comprises an alkaline polymer with the following molecular formula:

[0031]

[0032] Where n = 1000~3000; m = 1000~3000.

[0033] It is worth mentioning that, in this application, Ca is used in the alkaline polymer. 2+ If other alkaline earth metal ions are used instead, such as barium and magnesium, the base value will decrease. In addition, changing the metal ions may bring other unknown risks, such as changing its synergistic effect with other additives, thereby affecting the stability and final performance of the entire formulation.

[0034] More importantly, the alkaline polymer is used as an auxiliary additive. During use, since the temperature of the workpiece is usually around 800°C, when the workpiece comes into contact with the quenching agent containing the alkaline polymer, the alkaline polymer slowly decomposes and breaks down under thermal stress. The long alkyl chain portion in the molecular structure can accelerate the cooling rate after breaking down. The base oil and cooling accelerator in the quenching agent usually oxidize after contact with the workpiece, producing oxidation intermediates containing some acidic substances, including organic acids. After the alkaline polymer slowly decomposes and breaks down under thermal stress, the benzene ring side chain portion of its structure can neutralize and decompose the oxidation intermediates, thereby continuing to play an antioxidant role.

[0035] Specifically, after the alkaline polymer breaks down, it can encapsulate and adsorb the -SO3 or other acidic substances (such as organic acids) generated from the decomposition and consumption of other components, as well as CaO or free calcium ions (CaO or free calcium ions, when directly encountering acidic substances, will form calcium soaps if no interference occurs, which will lead to an increase in the viscosity of the quenching oil and the formation of sludge), and then recombine them into organic salts, such as (R-SO3)2Ca, to continue to neutralize the acidic substances and promote cooling speed and cleaning. Meanwhile, the calcium salicylate groups attached to the structure continue to act as antioxidants.

[0036] In one embodiment, the quenching agent for heat treatment comprises 0.9 to 7% by weight of the alkaline polymer.

[0037] According to another aspect of this application, the quenching agent for heat treatment described herein comprises the following components by weight percentage:

[0038] The above-mentioned alkaline polymer is present in amounts of 0.9% to 7%.

[0039] Base oil 72-95%;

[0040] 2-10% refrigerant;

[0041] Antioxidant 2-8%;

[0042] Brightener 0.1-3%.

[0043] Preferably, the base oil is a hydroisomerized base oil with extremely low sulfur, nitrogen, and aromatic hydrocarbon content (saturated hydrocarbons >99%), and high oxidation stability and high viscosity index.

[0044] Preferably, the cooling agent is selected from polyisobutylene polymers or a system formulated with its sulfonates, oil-soluble polymers, and nonionic surfactants. This significantly reduces the interfacial tension between the quenching oil and the metal surface, improving the oil's wettability and promoting the rupture of the vapor film formed on the workpiece surface at high temperatures. This allows the cooling process to rapidly transition from a slow vapor film stage to a vigorous and efficient boiling stage, thereby greatly enhancing the cooling capacity of the quenching oil in the high-temperature zone.

[0045] Also preferably, the antioxidant is implemented as a phenol or amine, a combination of phenols and amines, or a combination of sulfur / phosphorus antioxidants. It can capture initial free radicals, decompose oxidation intermediates, and slow down the oxidation rate.

[0046] Preferably, the brightener is an imidazoline derivative or an ester polymer, which can form a dense, non-sticky protective barrier film on the metal surface. This film is at the molecular level, allowing heat to pass through smoothly while blocking large molecular contaminants, thereby physically preventing oil degradation products from contacting the workpiece. It can also disperse trace amounts of colloidal substances and sludge generated by oxidation in the oil, preventing them from agglomerating into large particulate contaminants, thus achieving long-lasting high gloss.

[0047] Example 1

[0048] In a polymer molecule, n=1000, m=1000, 6% of the polymer is an alkaline polymer.

[0049] Base oil 80%;

[0050] 4% refrigerant;

[0051] Antioxidant 8%;

[0052] Brightener 2%.

[0053]

[0054] Example 2

[0055] In the polymer molecule, n=1500, m=1800, 6% is an alkaline polymer.

[0056] Base oil 80%;

[0057] 4% refrigerant;

[0058] Antioxidant 8%;

[0059] Brightener 2%.

[0060]

[0061] Example 3

[0062] In the polymer molecule, n=3000, m=3000, 6% is an alkaline polymer.

[0063] Base oil 80%;

[0064] 4% refrigerant;

[0065] Antioxidant 8%;

[0066] Brightener 2%.

[0067]

[0068] Comparative Example 1

[0069] In the polymer molecule, n=900, m=1000, 6% is an alkaline polymer.

[0070] Base oil 80%;

[0071] 4% refrigerant;

[0072] Antioxidant 8%;

[0073] Brightener 2%.

[0074]

[0075] Comparative Example 2

[0076] In the polymer molecule, n=3100, m=1000, 6% is an alkaline polymer.

[0077] Base oil 80%;

[0078] 4% refrigerant;

[0079] Antioxidant 8%;

[0080] Brightener 2%.

[0081]

[0082] Comparative Example 3

[0083] In the polymer molecule, n=900, m=1500, 6% is an alkaline polymer.

[0084] Base oil 80%;

[0085] 4% refrigerant;

[0086] Antioxidant 8%;

[0087] Brightener 2%.

[0088]

[0089] Comparative Example 4

[0090] In the polymer molecule, n=10, m=11, 6% is an alkaline polymer.

[0091] Base oil 80%;

[0092] 4% refrigerant;

[0093] Antioxidant 8%;

[0094] Brightener 2%.

[0095]

[0096] Comparative Example 5

[0097] A high-grade quenching oil is prepared according to the following percentage by weight: base oil 90%; petroleum resin 5%; stearate 2%; phenolic ester complex 2%; imidazoline oleate 1%.

[0098]

[0099] Those skilled in the art should understand that the embodiments of the present invention described above are merely examples and do not limit the invention. The objectives of the present invention have been fully and effectively achieved. The functions and structural principles of the present invention have been shown and explained in the embodiments, and any modifications or variations of the implementation of the present invention may be made without departing from the stated principles.

Claims

1. An alkaline polymer, characterized in that, Its molecular formula is as follows: Where n = 1000~3000; m = 1000~3000.

2. A quenching agent for heat treatment, characterized in that, The quenching agent for heat treatment comprises the following substances by weight percentage: 0.9-7% of the alkaline polymer as described in claim 1; Base oil 72-95%; 2-10% refrigerant; Antioxidant 2-8%; Brightener 0.1-3%.

3. The quenching agent for heat treatment according to claim 2, characterized in that, The base oil is implemented as a hydroisomerized base oil.

4. The quenching agent for heat treatment according to claim 2, characterized in that, The cooling agent is selected from at least one of polyisobutylene polymers or systems compounded with sulfonates, oil-soluble polymers, and nonionic surfactants.

5. The quenching agent for heat treatment according to claim 2, characterized in that, The antioxidant is implemented as a phenol or amine, a combination of phenols and amines, or a combination of sulfur / phosphorus antioxidants.

6. The quenching agent for heat treatment according to claim 2, characterized in that, The brightening agent is implemented as an imidazoline derivative or an ester polymer.

7. The use of the alkaline polymer as described in claim 1, characterized in that, It is used to prepare quenching agents for heat treatment.

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