A semi-synthetic cutting fluid with excellent stability, its preparation method and usage method

Abstract

The present invention discloses a semi-synthetic cutting fluid with excellent stability. By only using self-emulsifying esters as emulsifiers, on the basis of ensuring low foaming, resistance to hard water and lubrication, the number of raw materials can be reduced and the production process can be simplified. Moreover, by screening out a combination of basic additives, the aminolysis rate of the self-emulsifying ester can be significantly reduced, thereby achieving the purpose of extending the product warranty period. The present invention also discloses a preparation method and a usage method of a semi-synthetic cutting fluid with excellent stability. The key points of the present invention are: first, only self-emulsifying esters with better ammonia resistance are used as emulsifiers in the semi-synthetic cutting fluid; second, the selected combination of basic additives can also effectively reduce the aminolysis of the self-emulsifying ester. The combination of the above two aspects jointly extends the product warranty period.

Description

Technical Field

[0001] The present invention relates to a semi-synthetic cutting fluid with excellent stability, and a preparation method and a usage method thereof. Background Art

[0002] Water-based metal working fluids are widely used in metal processing industries such as cutting, grinding, rolling, and drawing due to their good cooling and cleaning effects and non-flammable characteristics, and have achieved good usage effects. Water-based metal working fluids are divided into three categories: emulsified oils, semi-synthetics, and full synthetics. In recent years, with the in-depth development of surfactant chemistry and the continuous improvement of water-based metal working fluid formulations, researchers have introduced self-emulsifying esters with both emulsifying and lubricating properties into the water-based semi-synthetic machining fluid formulation, and good practical application effects have been achieved in terms of emulsification and lubrication. The semi-synthetic machining fluid formulation generally includes base oil, organic acids, organic alkanolamines, emulsifiers, lubricating additives, coupling agents, rust inhibitors, bactericides, defoamers, and water. Introducing self-emulsifying esters into the formulation has significant advantages. For example, firstly, self-emulsifying esters can replace multiple emulsifiers, thereby reducing the number of raw materials in the formulation and simplifying the production process; secondly, self-emulsifying esters have excellent hard water resistance, and their addition improves the hard water stability of the formulation; thirdly, the foam in the formulation is controlled extremely low, reducing the risk of foam overflow on the on-site machine tools; fourthly, the presence of polyethoxy and ester functional groups in the structure of self-emulsifying esters themselves provides excellent lubricity, which can reduce the use of base oil and lubricants. The above advantages have also made various manufacturers compete to develop such products, but such products will encounter a fatal defect. Since most cutting fluids are alkaline, the presence of organic alkanolamines in semi-synthetic products with self-emulsifying esters as the main emulsifier will accelerate the aminolysis of self-emulsifying esters, resulting in poor stability of the stock solution, and thus phenomena such as stratification of the stock solution and inability to emulsify occur. Therefore, the quality guarantee period of such products on the market generally does not exceed half a year, or even more seriously, 3 months, and there are also frequent quality complaints from customers, which seriously affects the customer's usage experience and inventory cycle, and increases the overall operating costs of manufacturers and customers. Moreover, the products involved in the current technology generally use self-emulsifying esters as lubricating or functional auxiliary additives rather than as the main emulsifier, because the formulation with self-emulsifying esters as the main emulsifier has an aminolysis problem under alkaline conditions, resulting in unstable or non-emulsifiable stock solutions. Therefore, it is imperative to find a way to weaken or inhibit the aminolysis of self-emulsifying esters, thereby extending the quality guarantee period of the cutting fluid. Summary of the Invention

[0003] The object of the present invention is to overcome the defects of the prior art and provide a semi-synthetic cutting fluid with excellent stability. Only using self-emulsifying esters as emulsifiers, on the basis of ensuring low foam, hard water resistance, and lubrication, the number of raw materials can be reduced and the production process can be simplified; moreover, by screening the combination of alkaline additives, the aminolysis rate of self-emulsifying esters can be significantly reduced, thereby achieving the purpose of extending the product quality guarantee period.

[0004] Another object of the present invention is to provide a method for preparing a semi-synthetic cutting fluid with excellent stability.

[0005] One technical solution to achieve the above object is: A semi-synthetic cutting fluid with excellent stability, comprising components with the following weight percentage contents:

[0006]

[0007] For the above semi-synthetic cutting fluid with excellent stability, wherein, the structure of the self-emulsifying ester is as follows:

[0008]

[0009] Wherein, R1 is C14 Guerbet alcohol; R2 is a polyoxyethylene block copolymer with a molecular weight of 2000; R3 is -OH.

[0010] For the above semi-synthetic cutting fluid with excellent stability, wherein, the alkaline additive is a mixture of at least two of triethanolamine, N,N-dimethylethanolamine, N-methyldiethanolamine, 2-amino-2-methyl-1-propanol and potassium hydroxide.

[0011] For the above semi-synthetic cutting fluid with excellent stability, wherein, the base oil is selected as a naphthenic base oil with a viscosity range of 19 - 25 cst at 40 °C;

[0012] The polymeric castor oil acid ester is a tetrameric castor oil acid ester.

[0013] For the above semi-synthetic cutting fluid with excellent stability, wherein, the rust inhibitor is a mixture of sebacic acid and undecanedicarboxylic acid and dodecanedicarboxylic acid;

[0014] The antioxidant is benzotriazole and its derivative methylbenzotriazole;

[0015] The aluminum corrosion inhibitor is a commercially available modified siloxanone.

[0016] For the above semi-synthetic cutting fluid with excellent stability, wherein, the co-solvent is one or several of 1-phenoxy-2-propanol, 2-phenoxyethanol and diethylene glycol butyl ether.

[0017] For the above semi-synthetic cutting fluid with excellent stability, wherein, the bactericide is one or several of BK (hydroxyethyl hexahydrotriazine), BIT (benzisothiazolin-3-one) and BBIT (n-butyl-1,2-benzisothiazolin-3-one).

[0018] For the above semi-synthetic cutting fluid with excellent stability, wherein, the defoamer is a silicone defoamer.

[0019] The present invention also provides a method for preparing the above semi-synthetic cutting fluid with excellent stability, comprising the following steps:

[0020] S1, adding the self-emulsifying ester and the alkaline additive into a high-speed disperser for stirring, the rotation speed of the high-speed disperser is 10,000 - 20,000 revolutions per minute, and stirring for 1 h;

[0021] S2, adding the base oil, the polymerized castor oil acid ester, the rust inhibitor, the antioxidant, the aluminum corrosion inhibitor, the co-solvent, the bactericide, the defoamer and water into the high-speed disperser in sequence, and raising the temperature in the high-speed disperser to 40 - 50 °C, continuously stirring until it is uniformly transparent to obtain the semi-synthetic cutting fluid.

[0022] The present invention also provides a method for using the above semi-synthetic cutting fluid with excellent stability. During the cutting process, the semi-synthetic cutting fluid is dispersed in deionized water to form an emulsion system and used in the form of the emulsion. The mass concentration of the semi-synthetic cutting fluid stock solution in the emulsion system is 5% - 10%.

[0023] Adopting the technical solution of the semi-synthetic cutting fluid with excellent stability and its preparation method of the present invention, only using the self-emulsifying ester as the emulsifier, on the basis of ensuring low foaming, anti-hard water and lubrication, the number of raw materials can be reduced and the production process can be simplified; moreover, by screening out the combination of alkaline additives, the aminolysis rate of the self-emulsifying ester can be significantly reduced so as to achieve the purpose of extending the product quality guarantee period. Specific Embodiments

[0024] In order to enable those skilled in the art of the present technology to better understand the technical solution of the present invention, the following describes its specific embodiments in detail:

[0025] Example 1:

[0026] A semi-synthetic cutting fluid with excellent stability, composed according to the formulation in Table 1:

[0027] Table 1, Formulation Table of Example 1:

[0028] Component Content (wt%) Self-emulsifying ester 20.0 Alkaline additive 8.0 Base oil 30.0 Polymeric castor oil acid ester 8.0 Rust inhibitor 2.0 Antioxidant 0.5 Aluminum corrosion inhibitor 2.0 Cosolvent 2.6 Bactericide 2.0 Defoamer 0.5 Water Balance

[0029] Example 2:

[0030] A semi-synthetic cutting fluid with excellent stability using the self-emulsifying ester as the main emulsifier, composed according to the formulation in Table 2:

[0031] Table 2, Formulation Table of Example 2:

[0032]

[0033]

[0034] The preparation method of the semi-synthetic cutting fluid in Examples 1 to 2 can be prepared according to the following production steps:

[0035] Step A: Add the self-emulsifying ester and the alkaline additive to a high-speed disperser for stirring. The rotation speed of the high-speed disperser is 10,000 - 20,000 revolutions per minute, and stir for 1 h.

[0036] Step B: Add the base oil, polymerized castor oil acid ester, rust inhibitor, antioxidant, aluminum corrosion inhibitor, cosolvent, bactericide, defoamer and water to the high-speed disperser in sequence. Raise the temperature in the high-speed disperser to 40 - 50 °C, and continuously stir until it is uniformly transparent to obtain a semi-synthetic cutting fluid with excellent stability.

[0037] In Examples 1 and 2, the structure of the self-emulsifying ester is as follows:

[0038]

[0039] Among them, R1 is C14 Guerbet alcohol. The ester formed by the alcohol with a 14-carbon chain length and branched structure has a larger steric hindrance than the ester formed by the straight-chain alcohol with the same carbon chain length and the acid group, and the difficulty of ammonolysis of the ester group increases, which is beneficial to the stability of the self-emulsifying ester;

[0040] R2 is a polyoxyethylene block copolymer with a molecular weight of 2000, and its main function is to improve the hydrophilic ability of the self-emulsifying ester;

[0041] R3 is -OH. Here, the carboxyl group can combine with calcium and magnesium ions in water and improve the hard water resistance of the product under the action of the hydrophilic group of R2; second, the carboxyl group can react with fatty acids to form fatty amine salts to play an emulsifying ability.

[0042] The alkaline additive is a mixture of at least 2 kinds selected from triethanolamine, N,N-dimethylethanolamine, N-methyldiethanolamine, 2-amino-2-methyl-1-propanol and potassium hydroxide. The technical characteristics and functions of this alkaline additive combination:

[0043] When using monoethanolamine, isopropanolamine, diethanolamine, and diethylene glycol separately, the aminolysis rate of the self-emulsifying ester with primary or secondary amines is very fast, while using potassium hydroxide significantly slows down the decomposition rate of the self-emulsifying ester. Therefore, it is determined that the decomposition of the self-emulsifying ester belongs to aminolysis rather than hydrolysis. The aminolysis of the self-emulsifying ester in the cutting fluid is inevitable, but inorganic strong bases alone cannot be used as the buffer system because it is difficult to achieve antibacterial and rust prevention functions. In the present invention, alkanolamines with large steric hindrance and high degree of branching are screened for compatibility, which can significantly reduce the contact and collision between the outer electrons of N in the alkanolamine and the ester bond in the self-emulsifying ester, thereby reducing the aminolysis rate. Screening principles: First, the structure of the alkanolamine should be as branched as possible. Second, the alkanolamine must provide sufficient alkalinity reserve to ensure the antibacterial and rust prevention of the product. The screening results show that the compatibility of triethanolamine, N,N-dimethylethanolamine, N-methyldiethanolamine, 2-amino-2-methyl-1-propanol, and potassium hydroxide can effectively reduce the aminolysis rate of the self-emulsifying ester and extend the product quality guarantee period.

[0044] In Examples 1 and 2, the base oil is a naphthenic base oil with a viscosity range of 19 - 25 cst at 40 °C; the polymerized castor oil acid ester is a tetramerized castor oil acid ester. The rust inhibitor is a mixture of sebacic acid, undecanedicarboxylic acid, and dodecanedicarboxylic acid; the antioxidant is benzotriazole and its derivative methylbenzotriazole; the aluminum corrosion inhibitor is a commercially available modified siloxanone. The co-solvent is one or more of 1-phenoxy-2-propanol, 2-phenoxyethanol, and diethylene glycol butyl ether. The bactericide is one or more of BK, BIT, and BBIT. The defoamer is a silicone defoamer.

[0045] The present invention also provides a method for using a semi-synthetic cutting fluid with excellent stability. During the cutting process, the semi-synthetic cutting fluid is dispersed in deionized water to form an emulsion system and used in the form of an emulsion. The mass concentration of the above semi-synthetic cutting fluid stock solution in the emulsion system is 5% - 10%.

[0046] Reference Example

[0047] Two commercially available semi-synthetic cutting fluids A and B with self-emulsifying ester as the main emulsifier are selected as reference examples and compared with the examples for relevant performance. According to customer feedback, for products A and B, as long as the inventory exceeds three months, there will be phenomena such as non-emulsification or stratification of the newly prepared solution during the liquid preparation process.

[0048] Relevant performance tests are carried out on the finished cutting fluids of Examples 1, 2 and Reference Examples A and B to evaluate the quality guarantee periods of Examples 1, 2 and Reference Examples A and B involved in the present invention. The stock solution stabilities of 1, 2 and Reference Examples A and B and the emulsifiability of the stock solution after different storage periods (whether the dilution is transparent or semi-transparent) are respectively evaluated.

[0049] Description of the evaluation method:

[0050] (1) Place the concentrates of Examples 1 and 2 and Reference Examples A and B in an oven at 25 °C and 50 °C respectively, and record whether the stock solution is stable and whether the prepared 8% 100 ppm dilution is a transparent or semi-transparent solution every month until it is statistically determined that the stock solution is unstable or the prepared 8% 100 ppm dilution is unstable.

[0051] (2) The stock solution is considered unstable when it shows stratification, turbidity, or precipitation; the 8% 100 ppm dilution is considered unstable when the prepared dilution shows precipitation, oil separation, or stratification.

[0052] The test results are shown in Table 3:

[0053] Table 3. Performance Test Results

[0054]

[0055] Note: The limit storage time means that the stock solution and the dilution are stable in the current month, and the stock solution or the dilution becomes unstable in the next month.

[0056] As can be seen from Table 3, whether at 25 °C or 50 °C, the limit storage time of Examples 1 and 2 is significantly improved compared with Reference Examples A and B.

[0057] In summary, for the semi-synthetic cutting fluid with excellent stability using self-emulsifying ester as the main emulsifier in the present invention, on the basis of using the self-emulsifying ester involved in this patent, the quality guarantee period of the product can be significantly extended by the combination of at least two of the alkaline additives triethanolamine, N,N-dimethylethanolamine, N-methyldiethanolamine, 2-amino-2-methyl-1-propanol, and potassium hydroxide, meeting the quality guarantee period requirements of GB / T6144-2010. This invention solves the stability problem of the cutting fluid with self-emulsifying ester as the main emulsifier, not only retains the advantages of low foaming, high hard water resistance, and high lubrication of such products, but also improves the customer's usage experience and inventory cycle and reduces the overall operating costs of manufacturers and customers.

[0058] The key points of the semi-synthetic cutting fluid with excellent stability in the present invention are: first, only the self-emulsifying ester with better resistance to ammonolysis is used as the emulsifier in the semi-synthetic cutting fluid; second, the selected combination of alkaline additives can also effectively reduce the aminolysis of the self-emulsifying ester. The combination of the above two aspects jointly extends the quality guarantee period of the product.

[0059] What the present invention protects is the semi-synthetic cutting fluid with excellent stability, its preparation method and use method. The synthesis route of the self-emulsifying ester is not within the scope of discussion or protection of this technical solution.

[0060] In summary, the semi-synthetic cutting fluid with excellent stability, its preparation method and usage method of the present invention only use self-emulsifying esters as emulsifiers. On the basis of ensuring low foaming, hard water resistance and lubrication, the number of raw materials can be reduced and the production process can be simplified. Moreover, by screening the combination of alkaline additives, the aminolysis rate of the self-emulsifying ester can be significantly reduced, thereby achieving the purpose of extending the product warranty period.

[0061] Those of ordinary skill in the art should recognize that the above embodiments are only used to illustrate the present invention and are not intended to limit the present invention. As long as within the scope of the essential spirit of the present invention, changes and modifications to the above embodiments will fall within the scope of the claims of the present invention.

Claims

1. A semi-synthetic cutting fluid with excellent stability, characterized in that, Components comprising the following weight percentages: The structure of the self-emulsifying ester is as follows: Wherein, R1 is C14 Guerbet alcohol; R2 is a polyoxyethylene block copolymer with a molecular weight of 2000; R3 is -OH; The basic additive is a mixture of at least two of triethanolamine, N,N-dimethylethanolamine, N-methyldiethanolamine, 2-amino-2-methyl-1-propanol, and potassium hydroxide; The base oil is selected as a naphthenic base oil with a viscosity range of 19 - 25 cst at 40 °C; The polymerized ricinoleic acid ester is a tetramerized ricinoleic acid ester; The rust inhibitor is a mixture of sebacic acid and undecanedicarboxylic acid and dodecanedicarboxylic acid; The antioxidant is benzotriazole and its derivative methylbenzotriazole; The aluminum corrosion inhibitor is a modified siloxanone; The co-solvent is one or several of 1-phenoxy-2-propanol, 2-phenoxyethanol, and diethylene glycol butyl ether; The bactericide is one or several of BK, BIT, and BBIT; The defoamer is a silicone defoamer.

2. A preparation method of a semi-synthetic cutting fluid with excellent stability as described in claim 1, characterized in that, Including the following steps: S1, Add the self-emulsifying ester and the basic additive to a high-speed disperser for stirring. The rotation speed of the high-speed disperser is 10,000 - 20,000 revolutions per minute, and stir for 1 h; S2, Add the base oil, polymerized ricinoleic acid ester, rust inhibitor, antioxidant, aluminum corrosion inhibitor, co-solvent, bactericide, defoamer, and water to the high-speed disperser in sequence, and raise the temperature in the high-speed disperser to 40 - 50 °C, and continuously stir until it is uniformly transparent to obtain a semi-synthetic cutting fluid.

3. A method for using a semi-synthetic cutting fluid with excellent stability as described in claim 1, characterized in that, During the cutting process, disperse the semi-synthetic cutting fluid in deionized water to form an emulsion system, and use it in the form of an emulsion. The mass concentration of the semi-synthetic cutting fluid stock solution in the emulsion system is 5% - 10%.

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