High-efficiency silicone defoamer applicable to metalworking fluids, its preparation method and application

Abstract

The present application provides an efficient silicone defoamer applicable to metalworking fluids, its preparation method and application. The defoamer includes low-molecular-weight cycloalkyl-modified polydimethylsiloxane, nonionic emulsifier, zwitterionic emulsifier, surface activity regulator, anti-foaming layer enhancer and high-temperature resistance aid. By designing a silicone defoamer with low-molecular-weight cycloalkyl-modified polydimethylsiloxane as the core and supplemented with a composite emulsification system and functional aids, an efficient defoamer applicable to metalworking fluids is developed to ensure stability and rapid defoaming performance under high-temperature and high-shear conditions, meeting the requirements of modern working fluid conditions.

Description

Technical Field

[0001] The present application relates to the technical field of defoamers, and particularly to a high-efficiency silicone defoamer applicable to metalworking fluids, its preparation method and application. Background Art

[0002] Metalworking fluids, also known as metal cutting fluids or metal coolants, play important roles of cooling, lubricating, rust-proofing and cleaning in the metalworking process. However, during the process of liquid recycling and high-speed stirring, due to the mixing of air and the action of surfactants, a large amount of foam is extremely likely to be formed. The generation of foam not only affects the cooling and lubricating properties of the working fluid, but also causes unstable operation of the pump system, misjudgment of the liquid level and equipment failures, reducing the processing efficiency and product quality.

[0003] Existing metalworking fluid defoamers are mainly mineral oil, ester or silicone oil modified products, but there are problems such as foam regeneration, poor system compatibility, affecting the metal surface quality and high-temperature failure. Foam regeneration: After traditional defoamers quickly defoam, the foam suppression persistence is insufficient, and the foam is prone to reoccur, requiring frequent addition of defoamers. Poor system compatibility: Mineral oil-based defoamers are prone to stratification or form oil stains in water-based metalworking fluids, affecting the transparency and service performance of the working fluid. Affecting the metal surface quality: Some defoamers may form residues on the metal surface, resulting in a decline in the quality of subsequent painting or welding. High-temperature failure: Many defoamers are unstable under high-temperature and high-shear conditions and are difficult to meet the stringent requirements of modern metalworking fluids for defoamers.

[0004] With the rapid development of modern industry, the performance requirements for metalworking fluids are increasing day by day. There is a need for a high-efficiency and environmentally friendly defoamer with high defoaming efficiency, good foam suppression persistence and no negative impact on the performance of the working fluid to meet the requirements under complex working conditions. Summary of the Invention

[0005] The embodiments of the present application provide a high-efficiency silicone defoamer applicable to metalworking fluids, its preparation method and application to solve the problems existing in the related technologies. The technical solutions are as follows:

[0006] In the first aspect, the embodiments of the present application provide a high-efficiency silicone defoamer applicable to metalworking fluids, comprising the following raw materials in parts by weight:

[0007]

[0008] In one embodiment, the low molecular weight cycloalkyl-modified polydimethylsiloxane is obtained by introducing cycloalkyl side groups on the silicone oxygen main chain, and the structural formula of the low molecular weight cycloalkyl-modified polydimethylsiloxane is:

[0009] (CH3)3SiO-(Si(CH3)2O)m -(Si(CH3)(R1)O) n -Si(CH3)3;

[0010] R1 is a cycloalkyl group; preferably, R1 is cyclopentyl, cyclohexyl, or cycloheptyl; the ratio of m / n is 1:1 to 1:10; m = 1 - 50, n = 10 - 100, and m and n are integers.

[0011] In one embodiment, the low molecular weight cycloalkyl-modified polydimethylsiloxane is prepared by the following method:

[0012] Octamethylcyclotetrasiloxane and cycloalkylmethyldimethoxysilane are subjected to a ring-opening polymerization reaction in the presence of a catalyst; after the polymerization reaction is completed, hexamethyldisiloxane is used for end-capping to terminate the reaction; after separation, a low molecular weight cycloalkyl-modified polydimethylsiloxane is obtained. In one embodiment, the nonionic emulsifier is fatty alcohol polyoxyethylene ether, and the structural formula is:

[0013] R2-(OCH2CH2) o -OH;

[0014] R2 is a long-chain alkyl group with 10 - 18 carbon atoms or a phenyl group; o = 3 - 25, and o is an integer.

[0015] In one embodiment, the zwitterionic emulsifier is alkyl betaine, and the structural formula is:

[0016] R3-N + (CH3)2CH2COO - ;

[0017] R3 is a long-chain alkyl group with 10 - 18 carbon atoms.

[0018] In one embodiment, the surface activity regulator is a fluorine-modified polyether, and the structural formula is:

[0019] CF3(CF2) p CH2CH2O(CH2CH2O) q H;

[0020] p = 3 - 7, q = 5 - 15, and p and q are integers.

[0021] In one embodiment, the anti-foam layer enhancer is a vinyl-modified siloxane; the structural formula is:

[0022] (CH3)3SiO-[Si(CH3)(CH=CH2)O] y -Si(CH3)3;

[0023] y = 10 - 60, and y is an integer.

[0024] In one embodiment, the high-temperature resistant auxiliary agent is a high-temperature resistant fatty acid ester; the structural formula is:

[0025] R4COO(CH2CH2O) x H;

[0026] R4 is a long-chain alkyl group with 16-18 carbon atoms, x = 10-20, and x is an integer.

[0027] In a second aspect, an embodiment of the present application provides a preparation method of a high-efficiency silicone defoamer applicable to metal working fluids, including the following steps:

[0028] Step S1, under stirring, add a non-ionic emulsifier and an amphoteric ion emulsifier to the low-molecular-weight cycloalkyl-modified polydimethylsiloxane in a flowing state, and stir evenly; slowly heat up and keep warm to form a stable emulsion system;

[0029] Step S2, sequentially add a surface activity regulator, an anti-foam layer enhancer, and a high-temperature resistant auxiliary agent to the emulsion system, and stir and mix evenly after each addition;

[0030] Step S3, after mixing is completed, continue to stir and slowly cool down, and filter to obtain the high-efficiency silicone defoamer applicable to metal working fluids.

[0031] In one embodiment, in step S1, the non-ionic emulsifier is pre-dissolved at room temperature; the stirring rate is 500-1000 rpm; the low-molecular-weight cycloalkyl-modified polydimethylsiloxane is heated to 40-50 °C to reach a flowing state; slowly heat up to 60-70 °C and keep warm for 5-10 min.

[0032] In one embodiment, in step S2, the stirring rate is 700-1200 rpm; the stirring time is 10-15 min.

[0033] In one embodiment, in step S3, cool down to room temperature.

[0034] In a third aspect, an embodiment of the present application provides an application of the above-mentioned high-efficiency silicone defoamer applicable to metal working fluids in aqueous cutting fluids, oily grinding fluids, and high-temperature and high-speed cutting fluids.

[0035] The advantages or beneficial effects in the above technical solutions at least include:

[0036] The high-efficiency silicone defoamer applicable to metalworking fluids of the present application develops a high-efficiency defoamer applicable to metalworking fluids by designing a silicone defoamer with low-molecular-weight cycloalkyl-modified polydimethylsiloxane as the core, supplemented by a composite emulsification system and functional additives, ensuring stability and rapid defoaming performance under high-temperature and high-shear conditions and meeting the requirements of modern working fluid conditions.

[0037] The above summary is for the purpose of the specification only and is not intended to be limiting in any way. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features of the present application will become apparent from the following detailed description. Detailed Description of the Invention

[0038] In the following, only some exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various different ways without departing from the spirit or scope of the present application. Therefore, the description is considered to be exemplary in nature and not restrictive.

[0039] The defoamer for metalworking fluids is required to have rapid defoaming and long-lasting foam suppression performance, and at the same time have no negative impact on the lubricity, cooling property, and stability of metalworking fluids. However, existing defoamers have problems such as foam regeneration, poor system compatibility, affecting the surface quality of metals, and high-temperature failure. Therefore, in order to overcome the above problems and make the defoamer suitable for use in metalworking fluids, the present application provides a high-efficiency silicone defoamer applicable to metalworking fluids, including the following raw materials in parts by weight:

[0040]

[0041] Selecting low-molecular-weight polydimethylsiloxane can ensure stability and rapid defoaming performance under high-shear conditions; modifying it with cycloalkyl enhances the dispersibility and foam suppression persistence of silicone, preventing the defoamer from agglomerating or precipitating in the liquid; the composite emulsification system of non-ionic emulsifier and zwitterionic emulsifier improves the dispersibility of the defoamer in aqueous metalworking fluids, preventing oil spots or stratification problems; enhancing the stability of the defoamer under hard water conditions and avoiding emulsification failure. The use of surface activity regulators and anti-foam layer enhancers reduces the surface tension of the working fluid, accelerates the diffusion of the defoamer to the gas-liquid interface, and forms a stable anti-foam layer after the foam breaks, preventing foam regeneration; the high-temperature resistance additive can ensure the persistent performance of the defoamer under high-temperature and high-shear conditions and meet the requirements of modern working fluid conditions.

[0042] In one embodiment, the low-molecular-weight cycloalkyl-modified polydimethylsiloxane is obtained by introducing cycloalkyl side groups on the silicone main chain, and the structural formula of the low-molecular-weight cycloalkyl-modified polydimethylsiloxane is:

[0043] (CH3)3SiO-(Si(CH3)2O) m -(Si(CH3)(R1)O) n -Si(CH3)3;

[0044] R1 is a cycloalkyl group; preferably, R1 is cyclopentyl, cyclohexyl, or cycloheptyl; the ratio of m / n is 1:1 to 1:10; m = 1 - 50, n = 10 - 100, and m and n are integers.

[0045] Using low - molecular - weight cycloalkyl - modified polydimethylsiloxane as the core component, introducing cycloalkyl side groups on the silicone main chain, its unique molecular structure endows it with the ability to quickly diffuse to the gas - liquid interface, which can rapidly destroy the bubble film layer, prompt the collapse of bubbles, achieve excellent rapid defoaming effect, and can enhance the dispersibility and foam - suppressing persistence of silicone, preventing the defoamer from agglomerating or precipitating in the liquid.

[0046] In one embodiment, the low - molecular - weight cycloalkyl - modified polydimethylsiloxane is prepared by the following method:

[0047] Octamethylcyclotetrasiloxane and cycloalkylmethyldimethoxysilane carry out ring - opening polymerization reaction in the presence of a catalyst; after the polymerization reaction ends, hexamethyldisiloxane is used for end - capping to terminate the reaction; after separation, low - molecular - weight cycloalkyl - modified polydimethylsiloxane is obtained.

[0048] In one embodiment, the molar ratio of octamethylcyclotetrasiloxane to cycloalkylmethyldimethoxysilane is m / 4:n.

[0049] In one embodiment, the catalyst is KOH, and the mass concentration of the catalyst is 0.1% - 0.5%.

[0050] In one embodiment, the conditions for the ring - opening polymerization reaction are: under nitrogen protection, react at 80 - 100 °C for 4 - 8 h.

[0051] In one embodiment, hexamethyldisiloxane is added as an end - capping agent and the reaction continues for 1 - 2 h; acetic acid is added and the mass concentration of acetic acid is 0.1 - 0.5% to terminate the reaction.

[0052] In one embodiment, after the reaction ends, unreacted monomers and low - boiling - point by - products are removed by vacuum distillation.

[0053] In one embodiment, the polymer is washed with an organic solvent and dried to obtain pure low - molecular - weight cycloalkyl - modified polydimethylsiloxane.

[0054] In one embodiment, octamethylcyclotetrasiloxane and cycloalkylmethyldimethoxysilane are added to the reactor in a molar ratio of m / 4:n; KOH is added to make the mass concentration of sodium hydroxide 0.1%-0.5%; under nitrogen protection, the reaction is carried out at 80-100 °C for 4-8 h; ring-opening polymerization reaction is carried out;

[0055] After the polymerization reaction is completed, hexamethyldisiloxane is added as a capping agent and the reaction continues for 1-2 h; acetic acid is added to make the mass concentration of acetic acid 0.1-0.5% to terminate the reaction;

[0056] After the reaction is completed, unreacted monomers and low-boiling by-products are removed by vacuum distillation.

[0057] The polymer is washed with an organic solvent and dried to obtain pure low-molecular-weight cycloalkyl-modified polydimethylsiloxane.

[0058] In one embodiment, the cycloalkylmethyldimethoxysilane is one of cyclopentylmethyldimethoxysilane, cyclohexylmethyldimethoxysilane or cycloheptylmethyldimethoxysilane. In one embodiment, the non-ionic emulsifier is fatty alcohol polyoxyethylene ether, and the structural formula is:

[0059] R2-(OCH2CH2) o -OH;

[0060] R2 is a long-chain alkyl group or phenyl group with C10-C18; o = 3-25 and o is an integer.

[0061] The non-ionic emulsifier can improve the dispersibility of the defoamer in the water-based metal working fluid and prevent oil spots or stratification problems.

[0062] In one embodiment, the zwitterionic emulsifier is alkyl betaine, and the structural formula is:

[0063] R3-N + (CH3)2CH2COO - ;

[0064] R3 is a long-chain alkyl group with C10-C18.

[0065] The zwitterionic emulsifier can enhance the stability of the defoamer under hard water conditions and avoid emulsion failure.

[0066] The composite emulsification system composed of non-ionic emulsifier and zwitterionic emulsifier can form a stable microemulsion structure in the liquid and inhibit the formation of bubble nuclei. The anti-foam layer enhancer further inhibits the growth and diffusion of foam by forming a high-strength protective film at the gas-liquid interface. The two cooperate with each other, significantly prolonging the foam suppression time and meeting the long-time process requirements.

[0067] In one embodiment, the surface activity regulator is a fluorine-modified polyether, and its structural formula is:

[0068] CF3(CF2) p CH2CH2O(CH2CH2O) q H;

[0069] p = 3 - 7, q = 5 - 15, and p and q are integers.

[0070] In one embodiment, the antifoam layer enhancer is a vinyl-modified siloxane; its structural formula is:

[0071] (CH3)3SiO-[Si(CH3)(CH=CH2)O] y -Si(CH3)3;

[0072] y = 10 - 60, and y is an integer.

[0073] Using the fluorine-modified polyether as the surface activity regulator and the vinyl-modified siloxane as the antifoam layer enhancer can ensure the uniform distribution of the active ingredient in different matrices and maintain the physical and chemical properties of the metalworking fluid. It optimizes the distribution efficiency of the defoamer at the interface, thereby enhancing the overall defoaming speed. The defoamer has excellent compatibility and can exhibit good dispersibility in both water-based and oil-based metalworking fluids, without affecting the transparency and lubricity of the system, nor forming solid residues.

[0074] In one embodiment, the high-temperature resistance aid is a high-temperature resistant fatty acid ester; its structural formula is:

[0075] R4COO(CH2CH2O) x H;

[0076] R4 is a long-chain alkyl group with C16 - C18, x = 10 - 20, and x is an integer.

[0077] The high-temperature resistance aid of the present application is a fatty acid ester, which has a long-chain alkyl group and a polyethylene glycol structure, enhancing the thermal stability and shear stability of the molecular chain. It can still maintain stable performance under high-temperature and high-shear conditions, ensuring the continuous effectiveness of the defoamer under harsh working conditions. The synergistic effect with the core defoaming component enables the product to be widely applied to high-temperature metal processing, the petrochemical industry, and other harsh operating environments.

[0078] The present application also provides a preparation method for a highly efficient silicone defoamer applicable to metalworking fluids, including the following steps:

[0079] Step S1, under stirring, add a non-ionic emulsifier and an amphoteric ionic emulsifier to the low-molecular-weight cycloalkyl-modified polydimethylsiloxane in a flowing state, and stir evenly; slowly heat up and keep warm to form a stable emulsion system;

[0080] Step S2, sequentially add a surface activity regulator, an anti-foam layer enhancer, and a high-temperature resistance aid to the emulsion system, and stir after each addition to mix evenly;

[0081] Step S3, after mixing is completed, continue to stir and slowly cool down, and filter to obtain the high-efficiency silicone defoamer applicable to metalworking fluids.

[0082] In one embodiment, in step S1, the non-ionic emulsifier is pre-dissolved at room temperature; the stirring rate is 500 - 1000 rpm; the low-molecular-weight cycloalkyl-modified polydimethylsiloxane is heated to 40 - 50 °C to reach a flowing state; slowly heat up to 60 - 70 °C and keep warm for 5 - 10 min.

[0083] Pre-dissolving the non-ionic emulsifier and mixing the low-molecular-weight cycloalkyl-modified polydimethylsiloxane in a flowing state can ensure uniform mixing.

[0084] In one embodiment, in step S2, the stirring rate is 700 - 1200 rpm; the stirring time is 10 - 15 min. Controlling the stirring speed at a moderate 700 - 1200 rpm can avoid the generation of bubbles.

[0085] In one embodiment, in step S3, cool down to room temperature. After mixing is completed, slowly cool down to room temperature while continuing to stir to prevent component stratification; filter the final product to remove possible impurities or undissolved particles.

[0086] Next, a specific example is used for further illustration.

[0087] Example 1

[0088] By weight, 75 parts of low-molecular-weight cycloalkyl-modified polydimethylsiloxane, 12 parts of non-ionic emulsifier, 8 parts of amphoteric ionic emulsifier, 8 parts of surface activity regulator, 3 parts of anti-foam layer enhancer, and 2 parts of high-temperature resistance aid;

[0089] Among them, the structure of the low-molecular-weight cycloalkyl-modified polydimethylsiloxane is (CH3)3SiO-(Si(CH3)2O) m -(Si(CH3)(R1)O) n -Si(CH3)3; R1 is cyclohexyl (C6H 11), m = n = 50; Octamethylcyclotetrasiloxane and partially hydrolyzed cyclohexylmethyldimethoxysilane are added to the reactor in a molar ratio of 1:4; KOH is added to make the mass concentration of sodium hydroxide 0.3%; under nitrogen protection, the reaction is carried out at 90 °C for 6 h; ring-opening polymerization reaction is carried out; at the end of the polymerization reaction, hexamethyldisiloxane is added as a capping agent and the reaction continues for 1.5 h; acetic acid is added to make the mass concentration of acetic acid 0.3% to terminate the reaction; unreacted monomers and low-boiling by-products are removed by vacuum distillation; the polymer is washed with an organic solvent and dried with anhydrous magnesium sulfate to obtain the above-mentioned low-molecular-weight cyclohexyl-modified polydimethylsiloxane; the non-ionic emulsifier has a structure of R2-(OCH2CH2) o -OH; R2 is an alkyl group with 16 carbon atoms; o = 10;

[0090] The zwitterionic emulsifier has a structure of R3-N + (CH3)2CH2COO - ; R3 is an alkyl group with 16 carbon atoms;

[0091] The surface activity regulator has a structure of CF3(CF2) p CH2CH2O(CH2CH2O) q H; p = 5, q = 10;

[0092] The anti-foaming layer enhancer has a structure of (CH3)3SiO-[Si(CH3)(CH=CH2)O] y -Si(CH3)3; y = 40;

[0093] The high-temperature resistance aid has a structure of R4COO(CH2CH2O) x H; R4 is an alkyl group with 16 carbon atoms, x = 15;

[0094] Preparation steps:

[0095] Place the low-molecular-weight cycloalkyl-modified polydimethylsiloxane in a reaction kettle and heat it to 40 - 50 °C to make it in a flowing state; meanwhile, stir and pre-dissolve the non-ionic emulsifier at room temperature, and gradually add the non-ionic emulsifier and the zwitterionic emulsifier into the polydimethylsiloxane under the condition of continuous stirring at 500 - 1000 rpm; after stirring evenly, slowly raise the temperature to 60 - 70 °C and maintain it for 5 - 10 min to fully mix the two to form a stable emulsion system; successively add the surface activity regulator, the anti-foaming layer enhancer and the high-temperature resistance aid, and stir for 10 - 15 min after each addition to ensure the uniform distribution of each component; control the stirring speed at 700 - 1200 rpm to avoid the generation of bubbles; after mixing is completed, slowly cool down to room temperature while continuing to stir to prevent component stratification; filter the final product to remove possible impurities or undissolved particles to obtain the high-efficiency silicone defoamer suitable for metalworking fluids.

[0096] Example 2

[0097] By weight, 69 parts of low molecular weight cycloalkyl modified polydimethylsiloxane, 15 parts of non-ionic emulsifier, 5 parts of zwitterionic emulsifier, 10 parts of surface activity regulator, 3 parts of anti-foam layer enhancer, and 3 parts of high temperature resistant additive;

[0098] Among them, the structure of the low molecular weight cycloalkyl modified polydimethylsiloxane is (CH3)3SiO-(Si(CH3)2O) m -(Si(CH3)(R1)O) n -Si(CH3)3; R1 is cyclopentyl (C5H9), m = 10, n = 100; Octamethylcyclotetrasiloxane and partially hydrolyzed cyclopentylmethyldimethoxysilane are added to the reactor in a molar ratio of 1:40; KOH is added to make the mass concentration of sodium hydroxide 0.1%; Under nitrogen protection, react at 80 °C for 8 h; Carry out ring-opening polymerization reaction; After the polymerization reaction is completed, add hexamethyldisiloxane as a capping agent and continue to react for 1 h; Add acetic acid so that the mass concentration of acetic acid is 0.5% to terminate the reaction; Remove unreacted monomers and low-boiling by-products by vacuum distillation; Wash the polymer with an organic solvent and dry it with anhydrous magnesium sulfate to obtain the above-mentioned low molecular weight cyclopentyl modified polydimethylsiloxane;

[0099] The structure of the non-ionic emulsifier is R2-(OCH2CH2) o -OH; R2 is an alkyl group with 10 carbons; o = 3;

[0100] The zwitterionic emulsifier has a structure of R3-N + (CH3)2CH2COO - ; R3 is an alkyl group with 18 carbons;

[0101] The structure of the surface activity regulator is CF3(CF2) p CH2CH2O(CH2CH2O) q H; p = 3, q = 15;

[0102] The structure of the anti-foam layer enhancer is (CH3)3SiO-[Si(CH3)(CH=CH2)O] y -Si(CH3)3; y = 10;

[0103] The structure of the high temperature resistant additive is R4COO(CH2CH2O) x H; R4 is an alkyl group with 18 carbons, x = 10;

[0104] The preparation method is the same as that of Example 1.

[0105] Example 3

[0106] By weight, 60 parts of low molecular weight cycloalkyl modified polydimethylsiloxane, 13 parts of non-ionic emulsifier, 10 parts of zwitterionic emulsifier, 7 parts of surface activity regulator, 2 parts of anti-foam layer enhancer, 5 parts of high temperature resistance aid;

[0107] Among them, the structure of the low molecular weight cycloalkyl modified polydimethylsiloxane is (CH3)3SiO-(Si(CH3)2O) m -(Si(CH3)(R1)O) n -Si(CH3)3; R1 is cycloheptyl (C7H 13 ), m = 10, n = 50; Octamethylcyclotetrasiloxane and partially hydrolyzed cycloheptylmethyldimethoxysilane are added to the reactor in a molar ratio of 1:20; KOH is added to make the mass concentration of sodium hydroxide 0.5%; Under nitrogen protection, react at 100 °C for 4 h; Carry out ring-opening polymerization reaction; At the end of the polymerization reaction, hexamethyldisiloxane is added as a capping agent and continue to react for 2 h; Add acetic acid so that the mass concentration of acetic acid is 0.1% to terminate the reaction; Remove unreacted monomers and low-boiling by-products by vacuum distillation; Wash the polymer with an organic solvent and dry it with anhydrous magnesium sulfate to obtain the above-mentioned low molecular weight cycloheptyl modified polydimethylsiloxane;

[0108] The structure of the non-ionic emulsifier is R2-(OCH2CH2) o -OH; R2 is an alkyl group of C18; o = 25;

[0109] The zwitterionic emulsifier has a structure of R3-N + (CH3)2CH2COO - ; R3 is an alkyl group of C14;

[0110] The structure of the surface activity regulator is CF3(CF2) p CH2CH2O(CH2CH2O) q H; p = 4, q = 5;

[0111] The structure of the anti-foam layer enhancer is (CH3)3SiO-[Si(CH3)(CH=CH2)O] y -Si(CH3)3; y = 20;

[0112] The structure of the high temperature resistance aid is R4COO(CH2CH2O) x H; R4 is an alkyl group of C18, x = 20;

[0113] The preparation method is the same as that of Example 1.

[0114] Example 4

[0115] By weight, 72 parts of low molecular weight cycloalkyl-modified polydimethylsiloxane, 10 parts of non-ionic emulsifier, 7 parts of zwitterionic emulsifier, 5 parts of surface activity regulator, 1 part of anti-foam layer enhancer, 4 parts of high temperature resistance aid;

[0116] Among them, the structure of the low molecular weight cycloalkyl-modified polydimethylsiloxane is (CH3)3SiO-(Si(CH3)2O) m -(Si(CH3)(R1)O) n -Si(CH3)3; R1 is cyclohexyl (C6H 11 ), m = 20, n = 40; Octamethylcyclotetrasiloxane and partially hydrolyzed cyclohexylmethyldimethoxysilane are added to the reactor in a molar ratio of 1:8; KOH is added to make the mass concentration of sodium hydroxide 0.2%; Under nitrogen protection, react at 95 °C for 5 h; Carry out ring-opening polymerization reaction; At the end of the polymerization reaction, hexamethyldisiloxane is added as a capping agent and continue to react for 1.5 h; Add acetic acid so that the mass concentration of acetic acid is 0.4% to terminate the reaction; Remove unreacted monomers and low-boiling by-products by vacuum distillation; Wash the polymer with organic solvent and dry with anhydrous magnesium sulfate to obtain the above-mentioned low molecular weight cyclohexyl-modified polydimethylsiloxane; The structure of the non-ionic emulsifier is R2-(OCH2CH2) o -OH; R2 is an alkyl group of C12; o = 15;

[0117] The zwitterionic emulsifier has a structure of R3-N + (CH3)2CH2COO - ; R3 is an alkyl group of C10;

[0118] The surface activity regulator has a structure of CF3(CF2) p CH2CH2O(CH2CH2O) q H; p = 7, q = 12;

[0119] The anti-foam layer enhancer has a structure of (CH3)3SiO-[Si(CH3)(CH=CH2)O] y -Si(CH3)3; y = 30;

[0120] The high temperature resistance aid has a structure of R4COO(CH2CH2O) x H; R4 is an alkyl group of C16, x = 15;

[0121] The preparation method is the same as that of Example 1.

[0122] Example 5

[0123] By weight, 64 parts of low-molecular-weight cycloalkyl-modified polydimethylsiloxane, 14 parts of non-ionic emulsifier, 6 parts of zwitterionic emulsifier, 9 parts of surface activity regulator, 2 parts of anti-foam layer enhancer, 5 parts of high-temperature resistance aid;

[0124] Among them, the structure of the low-molecular-weight cycloalkyl-modified polydimethylsiloxane is (CH3)3SiO-(Si(CH3)2O) m -(Si(CH3)(R1)O) n -Si(CH3)3; R1 is cyclohexyl (C6H 11 ), m15, n = 90; Octamethylcyclotetrasiloxane and partially hydrolyzed cyclohexylmethyldimethoxysilane are added to the reactor in a molar ratio of 1:24; KOH is added to make the mass concentration of sodium hydroxide 0.4%; Under nitrogen protection, react at 85 °C for 7 h; Carry out ring-opening polymerization reaction; At the end of the polymerization reaction, hexamethyldisiloxane is added as a capping agent and continue to react for 1.5 h; Add acetic acid so that the mass concentration of acetic acid is 0.2% to terminate the reaction; Remove unreacted monomers and low-boiling by-products by vacuum distillation; Wash the polymer with an organic solvent and dry it with anhydrous magnesium sulfate to obtain the above-mentioned low-molecular-weight cyclohexyl-modified polydimethylsiloxane; The structure of the non-ionic emulsifier is R2-(OCH2CH2) o -OH; R2 is an alkyl group of C14; o = 20;

[0125] The zwitterionic emulsifier has a structure of R3-N + (CH3)2CH2COO - ; R3 is an alkyl group of C12;

[0126] The structure of the surface activity regulator is CF3(CF2) p CH2CH2O(CH2CH2O) q H; p = 6, q = 8;

[0127] The structure of the anti-foam layer enhancer is (CH3)3SiO-[Si(CH3)(CH=CH2)O] y -Si(CH3)3; y = 60;

[0128] The structure of the high-temperature resistance aid is R4COO(CH2CH2O) x H; R4 is an alkyl group of C16, x = 20;

[0129] The preparation method is the same as that of Example 1.

[0130] Comparative Example 1

[0131] By weight, 75 parts of polydimethylsiloxane, 12 parts of non-ionic emulsifier, 8 parts of zwitterionic emulsifier, 8 parts of surface activity regulator, 3 parts of anti-foam layer enhancer, 2 parts of high-temperature resistance aid;

[0132] Among them, the polydimethylsiloxane structure is (CH3)3SiO-(Si(CH3)2O) m -(Si(CH3)(R1)O) n -Si(CH3)3; R1 is methyl (-CH3), m = n = 50;

[0133] The non-ionic emulsifier structure is R2-(OCH2CH2) o -OH; R2 is a C16 alkyl group; o = 10;

[0134] The zwitterionic emulsifier is an alkane structure of R3-N + (CH3)2CH2COO - ; R3 is a C16 alkyl group;

[0135] The surface activity regulator structure is CF3(CF2) p CH2CH2O(CH2CH2O) q H; p = 5, q = 10;

[0136] The anti-foam layer enhancer structure is (CH3)3SiO-[Si(CH3)(CH=CH2)O] y -Si(CH3)3; y = 40;

[0137] The high-temperature resistance aid structure is R4COO(CH2CH2O) x H; R4 is a C16 alkyl group, x = 15;

[0138] The preparation method is the same as that of Example 1.

[0139] Comparative Example 2

[0140] By weight, 75 parts of low molecular weight cycloalkyl modified polydimethylsiloxane, 20 parts of non-ionic emulsifier, 8 parts of surface activity regulator, 3 parts of anti-foam layer enhancer, 2 parts of high-temperature resistance aid;

[0141] Among them, the low molecular weight cycloalkyl modified polydimethylsiloxane structure is (CH3)3SiO-(Si(CH3)2O) m -(Si(CH3)(R1)O) n -Si(CH3)3; R1 is cyclohexyl (C6H 11 ), m = n = 50;

[0142] The non-ionic emulsifier structure is R2-(OCH2CH2) o -OH; R2 is a C16 alkyl group; o = 10;

[0143] The surface activity regulator structure is CF3(CF2)p CH2CH2O(CH2CH2O) q H; p = 5, q = 10;

[0144] The structure of the antifoaming layer enhancer is (CH3)3SiO-[Si(CH3)(CH=CH2)O] y -Si(CH3)3; y = 40;

[0145] The structure of the high-temperature resistance aid is R4COO(CH2CH2O) x H; R4 is an alkyl group with 16 carbons, x = 15;

[0146] The preparation method is the same as that of Example 1.

[0147] Comparative Example 3

[0148] By weight, 75 parts of low molecular weight cycloalkyl-modified polydimethylsiloxane, 20 parts of zwitterionic emulsifier, 8 parts of surface activity regulator, 3 parts of antifoaming layer enhancer, and 2 parts of high-temperature resistance aid;

[0149] Among them, the structure of the low molecular weight cycloalkyl-modified polydimethylsiloxane is (CH3)3SiO-(Si(CH3)2O) m -(Si(CH3)(R1)O) n -Si(CH3)3; R1 is cyclohexyl (C6H 11 ), m = n = 50;

[0150] The zwitterionic emulsifier has a structure of R3-N + (CH3)2CH2COO - ; R3 is an alkyl group with 16 carbons;

[0151] The structure of the surface activity regulator is CF3(CF2) p CH2CH2O(CH2CH2O) q H; p = 5, q = 10;

[0152] The structure of the antifoaming layer enhancer is (CH3)3SiO-[Si(CH3)(CH=CH2)O] y -Si(CH3)3; y = 40;

[0153] The structure of the high-temperature resistance aid is R4COO(CH2CH2O) x H; R4 is an alkyl group with 16 carbons, x = 15;

[0154] The preparation method is the same as that of Example 1.

[0155] Comparative Example 4

[0156] By weight, 75 parts of low molecular weight cycloalkyl modified polydimethylsiloxane, 12 parts of non-ionic emulsifier, 8 parts of zwitterionic emulsifier, 8 parts of surface activity regulator, 2 parts of high temperature resistant additive;

[0157] Among them, the structure of the low molecular weight cycloalkyl modified polydimethylsiloxane is (CH3)3SiO-(Si(CH3)2O) m -(Si(CH3)(R1)O) n -Si(CH3)3; R1 is cyclohexyl (C6H 11 ), m = n = 50;

[0158] The structure of the non-ionic emulsifier is R2-(OCH2CH2) o -OH; R2 is an alkyl group of C16; o = 10;

[0159] The zwitterionic emulsifier has a structure of R3-N + (CH3)2CH2COO - ; R3 is an alkyl group of C16;

[0160] The structure of the surface activity regulator is CF3(CF2) p CH2CH2O(CH2CH2O) q H; p = 5, q = 10;

[0161] The structure of the high temperature resistant additive is R4COO(CH2CH2O) x H; R4 is an alkyl group of C16, x = 15;

[0162] The preparation method is the same as that of Example 1.

[0163] Comparative Example 5

[0164] By weight, 75 parts of low molecular weight cycloalkyl modified polydimethylsiloxane, 12 parts of non-ionic emulsifier, 8 parts of zwitterionic emulsifier, 8 parts of surface activity regulator, 3 parts of anti-foam layer enhancer;

[0165] Among them, the structure of the low molecular weight cycloalkyl modified polydimethylsiloxane is (CH3)3SiO-(Si(CH3)2O) m -(Si(CH3)(R1)O) n -Si(CH3)3; R1 is cyclohexyl (C6H 11 ), m = n = 50;

[0166] The structure of the non-ionic emulsifier is R2-(OCH2CH2) o -OH; R2 is an alkyl group of C16; o = 10;

[0167] The zwitterionic emulsifier has a structure of R3-N+ (CH3)2CH2COO - ; R3 is an alkyl group with 16 carbons;

[0168] The structure of the surface activity regulator is CF3(CF2) p CH2CH2O(CH2CH2O) q H; p = 5, q = 10;

[0169] The structure of the anti-foaming layer enhancer is (CH3)3SiO-[Si(CH3)(CH=CH2)O] y -Si(CH3)3; y = 40;

[0170] The preparation method is the same as that of Example 1.

[0171] Test condition settings:

[0172] 1. Place the aqueous cutting fluid in a circulation system, set the rotation speed of the circulation pump to 3000 rpm, and control the temperature at 50 °C; the composition of the aqueous cutting fluid is: polyoxyethylene alcohol ester 8%; carboxylate 8%; borate 15%; OP-10 3%; ethylene glycol monobutyl ether 2%; water 64%;

[0173] Add an anti-foaming agent: Add an anti-foaming agent at 0.1% of the total mass of the cutting fluid; mix evenly with a stirrer;

[0174] Data recording:

[0175] Use a standard foam measuring instrument to record the initial value of the foam height. Record the foam height every 10 seconds until the foam completely disappears. Continuously observe for 120 minutes and record whether the foam regenerates. The results are shown in Table 1:

[0176] Table 1 Defoaming performance in aqueous cutting fluid

[0177]

[0178]

[0179] As can be seen from Table 1, in Comparative Example 1, polydimethylsiloxane was used as the basic component without being modified by naphthenic hydrocarbons. The defoaming performance decreased significantly. It took twice as long to eliminate the foam to less than 5 mm, and the foam regenerated within 90 min, requiring repeated addition of the defoaming agent. In Comparative Examples 2 and 3, only a single emulsifier was used instead of the composite emulsifier, and the defoaming rate decreased compared with Example 1. Comparative Example 4 did not contain an anti-foam layer enhancer. After the initial 10 s, as the defoaming proceeded, the defoaming efficiency per unit time was relatively low because the anti-foam layer enhancer was absent, and the foam regenerated while bursting, resulting in a decrease in the defoaming efficiency. Comparative Example 5 did not contain a high-temperature resistant additive. At 50 °C, the influence of temperature was not very obvious initially, but as the defoaming agent stayed in the high-temperature environment, the defoaming performance was gradually affected and decreased.

[0180] 2. Place the application in the oily grinding fluid into a circulation system, set the circulation pump speed at 4000 rpm, and control the temperature at 80 °C; the components of the oily grinding fluid are: 70% base oil (synthetic oil); 15% extreme pressure additive (sulfurized fatty acid ester); 6% anti-wear agent (borate ester); 6% rust inhibitor (benzotriazole derivative); 3% antioxidant (fatty amine).

[0181] Add the defoaming agent: Add the defoaming agent at 0.05% of the total mass of the cutting fluid; mix evenly with a stirrer;

[0182] Data recording:

[0183] Use a standard foam measuring instrument to record the initial value of the foam height. Record the foam height every 15 seconds until the foam completely disappears. The results are shown in Table 2:

[0184] Table 2 Defoaming performance of the defoaming agent in the oily grinding fluid under high temperature and high shear

[0185]

[0186] As can be seen from Table 2, Example 1 and Comparative Examples 1-4 showed similar defoaming properties to those in the aqueous cutting fluid. However, it should be noted that Comparative Example 5 did not contain a high-temperature resistant additive. At 80 °C, the temperature showed a strong influence. Especially as the defoaming agent stayed in the high-temperature environment, the defoaming performance decreased significantly, the defoaming ability gradually decreased, and even within the observation time, the foam was not completely eliminated.

[0187] In summary, in response to the special requirements of metalworking fluids, the present application has developed a highly efficient silicone defoaming agent with fast defoaming, long-term foam suppression, excellent compatibility, and environmental friendliness. Through a series of experimental verifications, the defoaming agent of the present invention can significantly improve the performance of metalworking fluids, effectively reduce the equipment failure rate and energy consumption, and provide an efficient solution for the metal processing industry.

[0188] In the description of this specification, the descriptions referring to terms such as "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of this application. Moreover, the specific features, structures, materials, or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0189] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such feature. In the description of this application, "a plurality of" means two or more unless otherwise specifically defined.

[0190] As described above, the above is only the specific implementation manner of this application, but the protection scope of this application is not limited thereto. Any person skilled in the art within the technical scope disclosed in this application can easily think of various changes or substitutions, and these should all be covered within the protection scope of this application. Therefore, the protection scope of this application should be subject to the protection scope of the claims.

Claims

1. An efficient silicone defoamer applicable to metalworking fluids, characterized in that, Comprising the following raw materials in parts by weight: Low molecular weight cycloalkyl modified polydimethylsiloxane: 60 - 75 parts; Nonionic emulsifier: 10 - 15 parts; Amphoteric ion emulsifier: 5 - 10 parts; Surface activity regulator: 5 - 10 parts; Antifoam layer enhancer: 1 - 3 parts; High temperature resistant auxiliary agent: 2 - 5 parts; The low molecular weight cycloalkyl modified polydimethylsiloxane is obtained by introducing cycloalkyl side groups on the silicone oxygen backbone, and the structural formula of the low molecular weight cycloalkyl modified polydimethylsiloxane is: (CH3)3SiO- (Si(CH3)2O) m - (Si(CH3)(R1)O) n -Si(CH3)3; R1 is any one of cyclopentyl, cyclohexyl or cycloheptyl; the ratio of m / n is 1:1 ~ 1:10; m = 1 - 50, n = 10 - 100, and m, n are integers; The surface activity regulator is fluorine modified polyether, and the structural formula is: CF3 (CF2) p CH2CH2O(CH2CH2O) q H; p = 3 ~ 7, q = 5 ~ 15, and p, q are integers; The antifoam layer enhancer is vinyl-containing modified silicone oxygen, and the structural formula is: (CH3)3SiO-[Si(CH3)(CH=CH2)O]-Si(CH3)3; y -Si(CH3)3; y = 10 ~ 60, and y is an integer; The high temperature resistant auxiliary agent is high temperature resistant fatty acid ester, and the structural formula is: R4COO(CH2CH2O) x H; R4 is a long chain alkyl group of C16 - C18, x = 10 ~ 20, and x is an integer.

2. The high-efficiency silicone defoamer applicable to metalworking fluids according to claim 1, characterized in that, The low molecular weight cycloalkyl modified polydimethylsiloxane is prepared by the following method: Octamethylcyclotetrasiloxane and cycloalkylmethyldimethoxysilane carry out ring-opening polymerization reaction in the presence of a catalyst; after the polymerization reaction ends, hexamethyldisiloxane is used for end-capping to terminate the reaction; after separation, low molecular weight cycloalkyl modified polydimethylsiloxane is obtained.

3. The high-efficiency silicone defoamer applicable to metalworking fluids according to claim 1, wherein The nonionic emulsifier is fatty alcohol polyoxyethylene ether, and the structural formula is: R2-(OCH2CH2) o -OH; R2 is a long chain alkyl group of C10 - C18 or phenyl; o = 3 ~ 25, and o is an integer.

4. The high-efficiency silicone defoamer applicable to metalworking fluids according to claim 1, wherein The amphoteric ion emulsifier is alkyl betaine, and the structural formula is: R3-N + (CH3)2CH2COO − ; R3 is a long chain alkyl group of C10 - C18.

5. A preparation method of an efficient silicone defoamer applicable to metalworking fluids as described in any one of claims 1-4, characterized in that, Comprising the following steps: Step S1, under stirring, add the nonionic emulsifier and the amphoteric ion emulsifier to the low molecular weight cycloalkyl modified polydimethylsiloxane in a flowing state, and stir evenly; slowly heat up and keep warm to form a stable emulsion system; Step S2, sequentially add the surface activity regulator, the antifoam layer enhancer and the high temperature resistant auxiliary agent to the emulsion system, and stir after each addition to mix evenly; Step S3, after mixing is completed, continue to stir and slowly cool down, and filter to obtain the high-efficiency silicone defoamer applicable to metalworking fluids.

6. Application of the high-efficiency silicone defoamer applicable to metalworking fluids according to any one of claims 1 - 4 in aqueous cutting fluid, oily grinding fluid, and high temperature and high speed cutting fluid.

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