A low surface tension defoamer containing a fluorosurfactant and a method for its preparation

Abstract

The application discloses a low-surface-tension defoaming agent containing fluorine surfactant and a preparation method thereof. The defoaming agent takes modified fluorine-containing hydrophobic silicon dioxide as a defoaming core, takes perfluoropolyether oil as a carrier, and is compounded with fluorine-containing surfactant and silicone emulsifier. Through a specific adding sequence and the control of temperature and other parameters in the preparation process, the technical problems of poor compatibility of the fluorine-containing component with the defoaming system and easy stable foaming are successfully solved. The defoaming agent prepared by the application has extremely low surface tension and high and persistent defoaming and bubble suppressing performance, and has good emulsion stability, and is suitable for the fields of photoresist, high-end paint and other fields with extremely high requirements on surface tension.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of surface active technology, in particular to a low surface tension defoamer containing fluorine surfactant and a preparation method thereof. BACKGROUND

[0002] In the process of industrial production and scientific research, the generation of foam often affects production efficiency, product quality and equipment operation. The existence of foam may cause uneven coating, unstable reaction, incomplete cleaning, gas retention, product defects and other problems. Therefore, defoamer, as a functional additive that can inhibit or eliminate foam, is widely used in coatings, inks, papermaking, textiles, food, pharmaceuticals, petrochemical industry, sewage treatment, electronics industry and semiconductor manufacturing, etc. fields, especially in high-end industrial fields such as the preparation of photoresist, the production of high-end coatings and inks, and the use of electronic industry cleaning agents. In the preparation of photoresist, due to the extremely high requirements for surface tension, cleanliness and compatibility, foam will affect the uniformity of coating and the precision of pattern; in the production of high-end coatings and inks, the existence of foam will cause defects such as shrinkage hole, pinhole and poor leveling of coating film, ultimately affecting the product quality; in the use of electronic industry cleaning agent, such as semiconductor wafer cleaning and cleaning step in the process of manufacturing flat panel display panel, foam will reduce the cleaning efficiency and cause secondary pollution. Therefore, the development of a high-efficiency, stable, low-surface-tension and environmentally friendly defoamer has become an urgent need in the above-mentioned high-end application fields.

[0003] CN103611472A discloses a preparation method of fluorine-containing surfactant dimer diethylene glycol monomethyl ether [3-perfluoro-(1,3-dimethyl-2-isopropyl-1-butenyloxy)] isophthalate and its application research, and studies its surface tension, interfacial tension, foaming property of aqueous solution, wettability and emulsifying property. It is found that it has low surface tension, interfacial tension and excellent surface activity.

[0004] CN108865097A discloses a low surface interfacial tension high contact angle surfactant and a preparation method thereof, belonging to the technical field of surfactants. The components include fluorocarbon surfactant 15-25 parts by weight, alkyl phenol polyoxyethylene ether 40-60 parts by weight, polyquaternary ammonium salt polymer 40-60 parts by weight, and co-surfactant 40-60 parts by weight. The water lock agent can effectively reduce the surface tension and interfacial tension of the solution, increase the contact angle, has good temperature resistance and good stability, and can effectively reduce the water lock damage of low porosity and low permeability reservoirs.

[0005] In summary, the current fluorine-containing surface active technology can achieve low surface tension, but the stability, compatibility and long-term storage performance of the fluorine-containing component and the defoaming system are still insufficient. SUMMARY

[0006] To solve the above problems, the present application provides a low surface tension defoaming agent containing fluorine surfactant and a preparation method thereof, which successfully solves the technical problems of poor compatibility of fluorine components with the defoaming system, easy foam stability and poor long-term storage performance by using modified fluorine-containing hydrophobic silica as the defoaming core, fluorine-containing surfactant and silicone emulsifier as the carrier, and specific pretreatment modification and high-pressure homogenization process.

[0007] Specifically, the low surface tension defoaming agent containing fluorine surfactant comprises the following components by mass fraction: modified fluorine-containing hydrophobic silica 3-8 parts, perfluoropolyether oil 15-30 parts, fluorine-containing surfactant 1-5 parts, silicone emulsifier 1-3 parts, thickening agent 0.2-1 part, and deionized water 50-80 parts.

[0008] The preparation process of the modified fluorine-containing hydrophobic silica comprises the following steps:

[0009] Step (1-1) Dry and remove water from fumed silica powder; dry the fumed silica powder in a vacuum oven at a temperature of 120℃ for not less than 4h. This is to completely remove the physically adsorbed water on the surface and in the pores of the silica, preventing hydrolysis side reactions with the subsequent addition of silane modifiers. At the same time, the reaction solvent heptane is distilled for water removal treatment;

[0010] Step (1-2) Add 5 parts of dried fumed silica to 35-50 parts of heptane and disperse, then slowly add perfluorooctyltriethoxysilane modifier under stirring conditions until the amount of addition is 0.4-0.6 parts; after the addition is completed, reflux at 96-100℃ for 12-24h, cool to room temperature, separate the solid product, wash and dry to obtain modified fluorine-containing hydrophobic silica; the dropwise addition time of perfluorooctyltriethoxysilane modifier is ≥10min;

[0011] The specific surface area of the fumed silica powder is 150-300m 2 / g.

[0012] The dried fumed silica was charged into a reaction vessel and heptane was added. Under the protection of inert gas atmosphere, the stirring was started to make the mixture well dispersed and form a uniform slurry. Then, under continuous stirring, the perfluorooctyltriethoxysilane modifier was slowly and evenly added dropwise using a constant pressure dropping funnel. After the addition was completed, the reaction mixture was gradually heated to reflux temperature and kept at this temperature for reaction. During this process, the perfluorooctyltriethoxysilane molecules first underwent hydrolysis to form the corresponding silanol. Subsequently, these silanols underwent condensation reaction with the silanol groups on the surface of the fumed silica to form stable siloxysilicon covalent bonds, thereby firmly grafting the perfluorooctyl group onto the surface of the silica. This condensation reaction usually needs to continue for 12-24 h to ensure that the reaction is complete and the grafting rate is maximized; after the reaction was completed, the system was cooled to room temperature. The modified solid product was separated by filtration. In order to completely remove the physically adsorbed unreacted modifier, reaction byproducts and solvents, the filter cake was repeatedly washed with fresh solvent of the same type until no fluorine element or silane component was detected in the washing liquid; the washed filter cake was transferred to a vacuum drying oven and dried at a temperature of 80-100°C until the weight was constant, ensuring that all solvents were completely removed. Finally, the dried block product was subjected to necessary crushing and sieving treatment to obtain the final product, i.e. the modified fluorine-containing hydrophobic silica, in the form of white powder with good flowability.

[0013] The low surface tension defoamer containing fluorine surfactant provided by the application has the core technical advantage that the fundamental contradiction between high efficiency defoaming and system stability is solved through the synergistic effect of the components from the level of the molecular interface. The modified fluorine-containing hydrophobic silica is used as the defoaming core. The component has hydrophobicity and oleophobicity by grafting perfluoroalkyl chains on the surface of the gaseous silica, which greatly reduces the critical surface energy of the solid-liquid interface, makes it easier to invade and pierce the foam liquid film, and more importantly, the fluorocarbon chain structure forms a thermodynamically compatible homogeneous system with the perfluoropolyether oil carrier and the fluorine-containing surfactant, which fundamentally avoids phase separation and defoaming component inactivation caused by poor compatibility, and ensures the storage stability of the product. The perfluoropolyether oil carrier provides a low-energy background for the whole system due to its extremely low surface tension and chemical inertness, which not only promotes the rapid spreading of the defoamer droplets on the foam liquid film, but also reduces the spreading coefficient of the system through cooperation with the fluorine-containing surfactant, drives the fluorine-containing surfactant molecules to migrate to the gas-liquid interface at a very high speed, locally disturbs the Gibbs elasticity of the interface film and destroys the Marangoni effect compensation mechanism, thereby realizing the instantaneous collapse of the foam instead of forming a stable interface film. The bridging effect of the silicone emulsifier further strengthens the stability of the oil-water interface, and the three-dimensional network structure formed by the association of the thickening agent effectively inhibits the sedimentation of high-density inorganic particles and the floating of the oil phase, ensuring the kinetic stability. The whole formula design is closely linked, and the theoretical essence is to build a precise system that is thermodynamically compatible, dynamically stable, and synergistically enhanced in the interface behavior of each component, ultimately realizing the unification of rapid defoaming and long-term foam suppression in an extremely low surface tension environment.

[0014] Preferably, in step (1), the number average molecular weight of the perfluoropolyether oil is 5000-6000, and the dynamic viscosity at 25°C is 100-200 mPa·s.

[0015] Preferably, in step (1), the fluorine-containing surfactant is perfluoro(2-methyl-3-oxahexanoic acid).

[0016] Preferably, in step (1), the silicone emulsifier is polyether-modified polydimethylsiloxane.

[0017] The HLB value of the selected polyether-modified polydimethylsiloxane is between 8 and 12, which is an oil-in-water emulsion that allows hydrophobic components such as perfluoropolyether oil to be uniformly dispersed in water in the form of tiny droplets, forming a fine, stable, and transparent emulsion that is conducive to the use and function of the subsequent defoamer.

[0018] Preferably, in step (1), the thickening agent is hydrophobically modified hydroxyethyl cellulose.

[0019] The application further discloses the low-surface-tension defoaming agent containing the fluorine-containing surfactant and a preparation method thereof.

[0020] Step (1): raw materials are prepared according to a proportion, the modified fluorine-containing hydrophobic silicon dioxide is added into the perfluoropolyether oil, stirring and dispersing are carried out at a rotating speed of 300-500 r per minute for 20-40 minutes at 50-60 DEG C, and a uniform oily slurry is obtained;

[0021] Step (2): the oily slurry obtained in step (1) is cooled to 30-40 DEG C, the fluorine-containing surfactant and the silicone emulsifier are sequentially added, intermittent ultrasonic treatment is carried out on the mixture by using an ultrasonic wave with a power of 300-1000 W and a frequency of 20-40 KHz, the total time is 5-20 minutes, a premix emulsion is obtained, then deionized water with a total water addition amount of 40%-80% is slowly added into the premix emulsion for dilution and emulsification under the stirring speed of 400-600 r per minute, after the addition is completed, the stirring is continuously carried out for 20-30 minutes, a coarse emulsion is obtained, and the single grinding time of the circulating grinding is 5-10 minutes;

[0022] Step (3): the coarse emulsion obtained in step (2) is transferred into a sand mill, and zirconium oxide grinding beads are added into the sand mill, the filling rate of the grinding beads is 65%-75%, the material flow is 1-3 L / min, the rotating speed is 1200-1500 r per minute, and the circulating grinding is carried out for 2-4 times, and the grinding temperature is controlled to be less than or equal to 35 DEG C;

[0023] Step (4): the emulsion after sand milling treatment obtained in step (3) is cooled to 25-30 DEG C, the remaining deionized water and the thickening agent are added, and the stirring is carried out at the rotating speed of 200-400 r per minute for 30-60 minutes until the system is uniform and stable, and the low-surface-tension defoaming agent is obtained.

[0024] Preferably, in step (3), the intermittent ultrasonic treatment time is 3-6 s of working and 1-2 s of intermittent.

[0025] The intermittent mode of the ultrasonic treatment can effectively control the reaction temperature, prevent local overheating, allow the material to be redistributed during the intermittent period, make the energy action more uniform, and achieve better treatment effect.

[0026] Preferably, in step (4), the diameter of the zirconium oxide grinding beads is 0.3-0.6 mm.

[0027] Preferably, in step (5), after the stirring is completed, the product is filtered and packaged by using a 200-400 mesh filter screen, so as to remove large particles and ensure the clarity and stability of the product.

[0028] By filtering the final emulsion with a 200-400 mesh filter, the system can effectively remove any residual particles, agglomerates or impurities, further improving the purity, uniformity and storage stability of the defoamer, ensuring excellent compatibility and reliability in high-end applications, and avoiding defects or performance degradation caused by particles.

[0029] The present application adopts the process flow of oil phase construction → interface modification → water phase dilution → mechanical finishing → final stabilization. At 50-60℃, the viscosity of perfluoropolyether oil is reduced and the fluidity is enhanced, which can more effectively wet and disperse the modified fluorine-containing hydrophobic silica. Moderate stirring at 300-500 r / min is aimed at realizing uniform mixing, rather than introducing too many bubbles, to provide a stable and uniform oily slurry base for the subsequent steps. The temperature is reduced to 30-40℃ to prevent the subsequent addition of surfactants from being degraded by heat. The fluorine-containing surfactant is added first to dissolve in the oil phase, and then the silicone emulsifier is added. The two cooperate to form a composite film at the oil-water interface. The cavitation effect and microjet of ultrasonic treatment can realize efficient mixing and preliminary emulsification at the molecular level, ensuring that the emulsifier molecules are fully adsorbed at the oil-water interface, preparing for the next step of water phase dilution, and forming a stable "pre-mixed emulsion". After ultrasonic pre-emulsification, the system has a good emulsification foundation. Moderate stirring and slow water addition are used to smoothly complete the phase transition under low shear conditions, avoiding demulsification or generating a large amount of foam due to sudden water addition or high shear. Since the "coarse emulsion" has a wide particle size distribution and poor stability, high shear is used to efficiently break up the droplets and aggregates to submicron level, obtaining an emulsion with extremely narrow particle size distribution and high stability. The jacket temperature below 35℃ is a necessary requirement to protect the heat-sensitive fluorine-containing silicone active ingredients. After sanding, the emulsion temperature rises and is in a high-energy unstable state. Cooling to 25-30℃ returns it to a stable state. At this time, the remaining water and thickening agent are added, as the thickening agent will be degraded and ineffective under high shear during sanding. Low-speed stirring is used to slowly disperse the thickening agent, allowing it to hydrate and form a stable three-dimensional network structure, thereby kinetically locking the entire system, preventing delamination and sedimentation during storage, and completing the final shaping of the product.

[0030] Compared with the prior art, the present application has the following advantages:

[0031] 1. The present application introduces a modified fluorine-containing hydrophobic silica, perfluoropolyether oil and fluorine-containing surfactant in a synergistic combination to construct a defoamer with low surface tension, excellent defoaming and antifoaming performance, and high emulsion stability. The use of a water-based system solves the environmental, compatibility and cleaning problems of traditional fluorine-containing or oil-based defoamers. Finally, through a specific process route, the dispersibility and stability of the defoamer are improved.

[0032] 2.The application realizes multiple technical breakthroughs of environmental protection, high efficiency, stability and low surface tension through component optimization and process innovation, and has good application prospect and popularization value in high-end industrial defoaming applications. DETAILED DESCRIPTION

[0033] The embodiments of the present application are described below by specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the content disclosed in the specification. Obviously, the described examples are part of the examples of the present application, not all. Based on the examples in the present application, all other examples obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0034] The perfluoropolyether oil has a trade name of DS715, a number average molecular weight of 5600, and a dynamic viscosity of 136 mPa·s at 25℃;

[0035] The fluorine-containing surfactant is perfluoro(2-methyl-3-oxahexanoic acid);

[0036] The organic silicon emulsifier is polyether modified polydimethylsiloxane;

[0037] The thickening agent is hydrophobically modified hydroxyethyl cellulose.

[0038] Example 1

[0039] A low-surface-tension defoaming agent containing a fluorine-containing surfactant, comprising the following components by mass fraction: modified fluorine-containing hydrophobic silica 5 parts, perfluoropolyether oil 23 parts, fluorine-containing surfactant 3 parts, organic silicon emulsifier 2 parts, thickening agent 0.6 parts, and deionized water 65 parts;

[0040] The preparation process of the modified fluorine-containing hydrophobic silica includes the following steps:

[0041] Step (1-1) Dry the fumed silica powder to remove water; dry the fumed silica powder in a vacuum oven at a temperature of 120℃ for not less than 4h; at the same time, distill the reaction solvent heptane to remove water;

[0042] Step (1-2) According to the weight fraction, 5 parts of the dried fumed silica is added to 43 parts of heptane for dispersion, and the modified fluorooctyl triethoxysilane modifier is slowly added dropwise under stirring conditions until the dropwise amount is 0.5 parts; 10 min after the dropwise addition is completed, reflux at 98℃ for 16h, cool to room temperature, separate the solid product, and wash and dry to obtain the modified fluorine-containing hydrophobic silica;

[0043] The specific surface area of the fumed silica powder is 300 m 2 / g;

[0044] A low surface tension defoaming agent of fluorine-containing surfactant is prepared by the following process steps:

[0045] Step (1): The raw materials are weighed according to the proportion and prepared for use; the modified fluorine-containing hydrophobic silica is added to the perfluoropolyether oil, stirred and dispersed at a speed of 500 r / min for 30 min at 55℃ to obtain a uniform oily slurry;

[0046] Step (2): The oily slurry obtained in step (1) is cooled to 35℃, and the fluorine-containing surfactant and silicone emulsifier are added in turn. The mixture is treated intermittently by ultrasonic wave with a power of 600W and a frequency of 25KHz for a total time of 10min to obtain a premixed emulsion. Then, 50 parts of deionized water is slowly added to the premixed emulsion for dilution and emulsification under stirring at a speed of 500 r / min. After the addition is completed, the stirring is continued for 25min to obtain a coarse emulsion;

[0047] Step (3): The coarse emulsion obtained in step (2) is transferred to a sand mill, and zirconium oxide grinding beads are added to the mill. The filling rate of the grinding beads is 65%. The material is circulated and ground for 2 times at a flow rate of 2L / min and a speed of 1350 r / min per minute, with a grinding time of 8min each time, and the grinding temperature is controlled at 33℃;

[0048] Step (4): The emulsion after sand milling obtained in step (3) is cooled to 25℃, and the remaining deionized water and thickening agent are added. Stirring is carried out at a speed of 300 r / min for 40min until the system is uniform and stable, to obtain a low surface tension defoaming agent of fluorine-containing surfactant.

[0049] After testing the surface tension, defoaming performance, emulsion stability, compatibility and application performance of the obtained defoaming agent, the surface tension is measured to be 16.3mN / m, the defoaming time is 6.2s, the defoaming agent is uniform and has no stratification, the number of shrinkage holes after coating is 0 per field, there is no residue after cleaning, and the surface is clean.

[0050] Example 2

[0051] A low surface tension defoaming agent of fluorine-containing surfactant, comprising the following components by mass: modified fluorine-containing hydrophobic silica 3 parts, perfluoropolyether oil 15 parts, fluorine-containing surfactant 1 part, silicone emulsifier 1 part, thickening agent 0.2 parts, deionized water 50 parts;

[0052] The preparation process of the modified fluorine-containing hydrophobic silica includes the following steps:

[0053] Step (1-1): Dry the fumed silica powder to remove water; dry the fumed silica powder in a vacuum oven at a temperature of 120℃ for not less than 4h; distill the reaction solvent heptane to remove water;

[0054] Step (1-2) 5 parts of dried fumed silica was dispersed in 35 parts of heptane, and then the perfluorooctyltriethoxysilane modifier was slowly added dropwise under stirring until the amount of the modifier was 0.4 parts; the dropwise addition was completed in 11 min, and the system was refluxed at 96°C for 24 h, cooled to room temperature, and then the solid product was separated, washed, and dried to obtain the modified fluorine-containing hydrophobic silica;

[0055] The specific surface area of the fumed silica powder was 150 m 2 / g;

[0056] The low-surface-tension defoaming agent containing a fluorine-containing surfactant was prepared by the following process steps:

[0057] Step (1): The raw materials were weighed according to the proportions and reserved; the modified fluorine-containing hydrophobic silica was added to the perfluoropolyether oil, and stirred and dispersed at a speed of 500 r / min for 30 min at 55°C to obtain a uniform oily slurry;

[0058] Step (2): The oily slurry obtained in step (1) was cooled to 35°C, and then the fluorine-containing surfactant and the silicone emulsifier were added in sequence, and the mixture was intermittently treated by ultrasonic waves with a power of 600 W and a frequency of 25 KHz for a total time of 10 min to obtain a premix emulsion, and then 50 parts of deionized water was slowly added to the premix emulsion for dilution and emulsification under stirring at a speed of 500 r / min, and after the addition was completed, the stirring was continued for 25 min to obtain a coarse emulsion;

[0059] Step (3): The coarse emulsion obtained in step (2) was transferred to a sand mill, and zirconium oxide grinding beads were added to the mill, and the filling rate of the grinding beads was 65%; the material flow was 2 L / min, and the grinding was carried out at a speed of 1500 r / min for 2 cycles, each cycle for 5 min, and the grinding temperature was controlled at 35°C;

[0060] Step (4): The sand-milling treated emulsion obtained in step (3) was cooled to 25°C, and the remaining deionized water and thickening agent were added, and the stirring was carried out at a speed of 300 r / min for 40 min until the system was uniform and stable, and then a low-surface-tension defoaming agent containing a fluorine-containing surfactant was obtained.

[0061] After the surface tension, defoaming performance, emulsion stability, and compatibility and application performance of the obtained defoaming agent were tested, it was found that the surface tension was 16.8 mN / m, the defoaming time was 6.5 s, the defoaming agent was uniform and had no stratification, the number of shrinkage holes after coating was 0 per field, there was no residue after cleaning, and the surface was clean.

[0062] Example 3

[0063] A low surface tension defoaming agent containing fluorine surfactant, comprising the following components by mass fraction: modified fluorine-containing hydrophobic silica 8 parts, perfluoropolyether oil 30 parts, fluorine-containing surfactant 5 parts, silicone emulsifier 3 parts, thickening agent 1 part, deionized water 80 parts;

[0064] The preparation process of the modified fluorine-containing hydrophobic silica comprises the following steps:

[0065] Step (1-1) Dry the fumed silica powder to remove water; dry the fumed silica powder in a vacuum oven at a temperature of 120°C for not less than 4h; distill the reaction solvent heptane to remove water;

[0066] Step (1-2) According to the weight fraction, 5 parts of dried fumed silica is added to 50 parts of heptane for dispersion, and perfluorooctyltriethoxysilane modifier is slowly added dropwise under stirring conditions until the dropwise amount is 0.6 parts; 10min after the dropwise addition is completed, reflux at 100°C for 12h, cool to room temperature, separate the solid product, and wash and dry to obtain modified fluorine-containing hydrophobic silica;

[0067] The specific surface area of the fumed silica powder is 300m 2 / g;

[0068] Step (1): Weigh the raw materials according to the proportion for standby; add the modified fluorine-containing hydrophobic silica to the perfluoropolyether oil, stir and disperse at a speed of 500r per minute at 55°C for 30min to obtain a uniform oily slurry;

[0069] Step (2): Cool the oily slurry obtained in step (1) to 35°C, and then add the fluorine-containing surfactant and the silicone emulsifier successively, and intermittently treat the mixture with ultrasonic waves with a power of 600W and a frequency of 25KHz for a total time of 10min to obtain a premix emulsion, and then slowly add 50 parts of deionized water to the premix emulsion for dilution and emulsification at a stirring speed of 500r per minute, and continue to stir for 25min after the addition is completed to obtain a coarse emulsion;

[0070] Step (3): Transfer the coarse emulsion obtained in step (2) to a sand mill, and add zirconium oxide grinding beads to the mill, and the filling rate of the grinding beads is 65%; circulate and grind the material under the conditions of a material flow rate of 2L / min and a speed of 1200r per minute for 2 times, each time for 10min, and control the grinding temperature to be 34°C;

[0071] Step (4): Cool the emulsion obtained after sand milling in step (3) to 25°C, add the remaining deionized water and thickening agent, and stir at a speed of 300r per minute for 40min until the system is uniform and stable, to obtain a low surface tension defoaming agent containing fluorine surfactant.

[0072] After the surface tension, defoaming performance, emulsion stability, and compatibility and application performance of the obtained defoaming agent were tested, the surface tension was 16.6 mN / m, the defoaming time was 6.7 s, the defoaming agent was uniform and had no stratification, the number of shrinkage holes after coating was 0 per field, and there was no residue after cleaning, and the surface was clean.

[0073] Comparative Example 1

[0074] The difference from Example 1 is only that in step (1), 10 parts of modified fluorine-containing hydrophobic silica, 40 parts of perfluoropolyether oil, 8 parts of fluorine-containing surfactant, 5 parts of silicone emulsifier, 2 parts of thickening agent, and 100 parts of deionized water were weighed.

[0075] After the surface tension, defoaming performance, emulsion stability, and compatibility and application performance of the obtained defoaming agent were tested, the surface tension was 20.2 mN / m, the defoaming time was 10.1 s, the defoaming agent was slightly stratified, the number of shrinkage holes after coating was 4 per field, and white mist shadows were visible on the surface after cleaning.

[0076] Comparative Example 2

[0077] The difference from Example 1 is only that in step (1), 10 parts of modified fluorine-containing hydrophobic silica, 40 parts of perfluoropolyether oil, 8 parts of fluorine-containing surfactant, 5 parts of silicone emulsifier, 2 parts of thickening agent, and 100 parts of deionized water were weighed.

[0078] After the surface tension, defoaming performance, emulsion stability, and compatibility and application performance of the obtained defoaming agent were tested, the surface tension was 20.2 mN / m, the defoaming time was 10.1 s, the defoaming agent was slightly stratified, the number of shrinkage holes after coating was 4 per field, and white mist shadows were visible on the surface after cleaning.

[0079] Comparative Example 3

[0080] The difference from Example 1 is only that in step (1), the modified fluorine-containing hydrophobic silica was added to the perfluoropolyether oil, and stirred and dispersed at a speed of 500 r / min per minute at 70°C for 30 min.

[0081] After the surface tension, defoaming performance, emulsion stability, and compatibility and application performance of the obtained defoaming agent were tested, the surface tension was 24.5 mN / m, the defoaming time was 16.8 s, the defoaming agent was obviously stratified, the number of shrinkage holes after coating was 10 per field, and slight oil stains were visible on the surface after cleaning.

[0082] Comparative Example 4

[0083] The difference from Example 1 is only that in step (1), the modified fluorine-containing hydrophobic silica was added to the perfluoropolyether oil, and stirred and dispersed at a speed of 500 r / min per minute at 40°C for 30 min.

[0084] After the surface tension, defoaming performance, emulsion stability, and compatibility and application performance of the obtained defoaming agent were tested, it was found that the surface tension was 25.2 mN / m, the defoaming time was 17.2 s, the oil phase of the defoaming agent was obviously floated, the number of shrinkage holes after coating was 8 per field, and slight oil stains were visible on the surface after cleaning.

[0085] Comparative Example 5

[0086] The difference from Example 1 is only that no ultrasonic treatment is performed in step (2).

[0087] After the surface tension, defoaming performance, emulsion stability, and compatibility and application performance of the obtained defoaming agent were tested, it was found that the surface tension was 30.5 mN / m, the defoaming time was 19.6 s, the oil phase of the defoaming agent was obviously floated, the number of shrinkage holes after coating was 12 per field, and obvious oil stains were visible on the surface after cleaning.

[0088] Comparative Example 6

[0089] The difference from Example 1 is only that homogenization treatment is used instead of sand mill treatment in step (3).

[0090] After the surface tension, defoaming performance, emulsion stability, and compatibility and application performance of the obtained defoaming agent were tested, it was found that the surface tension was 25.6 mN / m, the defoaming time was 18.2 s, the oil phase of the defoaming agent was obviously floated, the number of shrinkage holes after coating was 10 per field, and obvious oil stains were visible on the surface after cleaning.

[0091] Comparative Example 7

[0092] The difference from Example 1 is only that the silicone emulsifier is added first, and then the fluorine-containing surfactant is added in step (2).

[0093] After the surface tension, defoaming performance, emulsion stability, and compatibility and application performance of the obtained defoaming agent were tested, it was found that the surface tension was 22.4 mN / m, the defoaming time was 15.6 s, the oil phase of the defoaming agent was obviously floated, the number of shrinkage holes after coating was 9 per field, and slight oil stains were visible on the surface after cleaning.

[0094] Comparative Example 8

[0095] The difference from Example 1 is only that the thickening agent is added at the same time as the sand mill treatment in step (3), and only the remaining deionized water is added after the emulsion is cooled to 25-30°C.

[0096] The surface tension, defoaming performance, emulsion stability, and compatibility and application performance of the obtained defoaming agent were tested, and the surface tension was 19.8 mN / m, the defoaming time was 13.8 s, the oil phase of the defoaming agent was obviously floated, the number of shrinkage holes after coating was 7 per field, and slight oil stains were visible on the surface after cleaning.

[0097] Comparative Example 9

[0098] The grinding temperature of the sanding treatment in step (4) was 37℃.

[0099] The surface tension, defoaming performance, emulsion stability, and compatibility and application performance of the obtained defoaming agent were tested, and the surface tension was 17.6 mN / m, the defoaming time was 12.8 s, the oil phase of the defoaming agent was obviously floated, the number of shrinkage holes after coating was 6 per field, and slight oil stains were visible on the surface after cleaning.

[0100] Comparative Example 10

[0101] The difference from Example 1 is only that the fumed silica powder with a specific surface area of 300 m 2 / g was directly used without modification.

[0102] The surface tension, defoaming performance, emulsion stability, and compatibility and application performance of the obtained defoaming agent were tested, and the surface tension was 26.5 mN / m, the defoaming time was 18.5 s, the oil phase of the defoaming agent was obviously floated, the number of shrinkage holes after coating was 13 per field, and obvious oil stains were visible on the surface after cleaning.

[0103] Comparative Example 11

[0104] The difference from Example 1 is only that the fumed silica powder was modified by silane coupling agent KH570.

[0105] The surface tension, defoaming performance, emulsion stability, and compatibility and application performance of the obtained defoaming agent were tested, and the surface tension was 23.8 mN / m, the defoaming time was 16.5 s, the oil phase of the defoaming agent was obviously floated, the number of shrinkage holes after coating was 11 per field, and slight oil stains were visible on the surface after cleaning.

[0106] Comparative Example 12

[0107] The difference from Example 1 is only that the perfluorooctyltriethoxysilane modifier was added dropwise for 9 min.

[0108] The surface tension, defoaming performance, emulsion stability, and compatibility and application performance of the obtained defoaming agent were tested, and the surface tension was 18.5 mN / m, the defoaming time was 10.5, the defoaming agent was slightly layered, the number of shrinkage holes after coating was 4 per field, and white fog shadows were visible on the surface after cleaning.

[0109] Performance test:

[0110] Surface tension test: The surface tension of the defoamer aqueous solution was tested at 25°C by using a surface tension meter with a ring method.

[0111] Defoaming performance test: A certain amount of foaming liquid was added into a beaker and stirred vigorously to generate stable foam. Then a certain amount of defoamer was added and the defoaming time, i.e. the time from the highest point of the foam to the time when the foam basically disappeared, was recorded.

[0112] Emulsion stability test: The defoamer emulsion was stored at 25°C and the state after 30 days was observed to see whether there was layering or oil phase separation.

[0113] Compatibility and application performance test: The defoamer was added into the simulated photoresist, paint and cleaning agent matrix in a certain proportion, and coating and cleaning experiments were carried out. The number of pinholes in the field of view and the surface residual marks were observed.

[0114] The performance test results are shown in Table 1.

[0115] Table 1 Test results of examples and comparative examples

[0116]

[0117] In the examples, the fluorocarbon chain of the modified fluorine-containing hydrophobic silica, the perfluoropolyether oil and the fluorine-containing surfactant form a thermodynamically compatible low-energy interfacial system, which can efficiently reduce the gas-liquid surface energy; the silicone emulsifier precisely anchors the oil-water interface, strengthening the dispersion stability; the thickening agent builds a three-dimensional network at the appropriate stage, inhibiting particle sedimentation and oil phase floating; the oil phase dispersion temperature of 50-60°C takes into account the flowability of the perfluoropolyether oil and the stability of the components, ensuring uniform wetting of the modified silica; the order of adding the fluorine-containing surfactant first and then the silicone emulsifier at 30-40°C allows the two to be adsorbed in order at the interface; ultrasonic intermittent treatment realizes molecular-level mixing through cavitation effect, laying the foundation for emulsification; the high shear force of sand milling breaks the droplets to submicron level, and the temperature control of ≤35°C avoids the degradation of active components, finally forming a kinetically stable homogeneous system.

[0118] Compared with Example 1, the surface tension of Comparative Example 1 is high, the defoaming speed is slow, and the emulsion is slightly stratified. The use amount of each component is lower than the optimized range of the example, and the concentration of the modified fluorine-containing hydrophobic silica and perfluoropolyether oil is insufficient to fully cover the gas-liquid interface to reduce the surface energy. The fluorine-containing surfactant and the silicone emulsifier cannot effectively strengthen the interface stability, resulting in an increase in surface tension, slow defoaming, and slight stratification of the emulsion. The lack of active ingredients during coating causes shrinkage and residue. The use amount of each component in Comparative Example 2 is too high, exceeding the upper limit of system compatibility. Excessive modified silica is prone to agglomeration, and excessive perfluoropolyether oil is difficult to emulsify, which destroys the interface balance, causing the surface tension to rise, the defoaming efficiency to decrease, and the excessive components to further destabilize the system, resulting in stratification and shrinkage. In Comparative Example 3, the oil phase dispersion temperature is increased to 70°C, exceeding the reasonable range of the example. High temperature causes the perfluoropolyether oil to volatilize slightly, and the fluorine-containing surfactant to partially degrade, which destroys the wet dispersion of the modified silica to the oil phase, resulting in uneven distribution of active ingredients, an increase in interface energy, slow defoaming, and floating of the oil phase, increasing coating defects. In Comparative Example 4, the dispersion temperature is reduced to 40°C, and the viscosity of the perfluoropolyether oil is too high to fully wet the modified silica. Uneven dispersion leads to a failure of active ingredient synergy, a significant deterioration in surface tension and defoaming time, and floating of the oil phase due to insufficient dispersion. In Comparative Example 5, ultrasonic treatment is not performed, and the lack of cavitation effect results in molecular-level mixing. The fluorine-containing surfactant and the silicone emulsifier cannot be uniformly adsorbed at the interface, the pre-mixed emulsion interface film is incomplete, and subsequent steps cannot compensate, leading to a significant increase in surface tension, extremely slow defoaming, floating of the oil phase due to unstable interface, and severe coating defects and residue. In Comparative Example 6, homogenization is used instead of sand milling, and the lack of shear force cannot break the coarse emulsion droplets and particles to submicron level, resulting in a wide emulsion particle size distribution, poor stability, and a failure of active ingredients to efficiently contact the foam, leading to poor surface tension and defoaming time, easy floating of the oil phase, and many coating defects. In Comparative Example 7, the order of surfactant addition is changed. Adding the silicone emulsifier first will preferentially occupy the adsorption sites on the surface of the modified silica, hindering the fluorine-containing surfactant and the perfluoropolyether oil from synergistically reducing the surface energy, decreasing the compatibility of the interface film, increasing the surface tension, slowing down the defoaming, and causing the oil phase to float and increase coating defects. In Comparative Example 8, a thickening agent is added during sand milling. High shear destroys the three-dimensional network of the thickening agent, rendering it ineffective. Subsequent addition of water cannot compensate for the kinetic stability of the system, resulting in floating of the oil phase, slow defoaming, and coating defects. In Comparative Example 9, the sand milling temperature is increased to 37°C, exceeding the upper temperature limit. Partial degradation of the silicone emulsifier decreases the strength of the interface film, the fluorocarbon chain of the modified silica is slightly deformed, the defoaming efficiency is reduced, the surface tension and defoaming time are deteriorated, the oil phase floats, and there are defects in coating. In Comparative Example 10, unmodified fumed silica is used. The hydrophilic surface cannot be compatible with the perfluoropolyether oil, and a low-energy interface system cannot be formed, which instead destroys the stability of the emulsion, resulting in extremely high surface tension, extremely slow defoaming, severe floating of the oil phase, and significant coating defects and residue.Comparative Example 11: silica modified with KH570, KH570 without fluorocarbon chain cannot synergistically reduce surface energy with perfluoropolyether oil and fluorine-containing surfactant, and can only achieve basic hydrophobicity, the effect is much worse than the examples, resulting in increased surface tension, slow defoaming, and the oil phase floating due to insufficient compatibility; Comparative Example 12: the dropping time of the modifier is shortened to 9 min, and the uneven distribution of the modifier on the surface of the silica is caused by the too fast dropping speed, local agglomeration or insufficient modification, the modified silica cannot be uniformly dispersed in the oil phase, the synergistic effect is weakened, the surface tension is increased, the defoaming is slow, the emulsion is slightly layered, and the coating is defective.

[0119] The above description is only the preferred specific implementation of the present application, but the protection scope of the present application is not limited thereto, any person skilled in the art can make equivalent replacement or change according to the technical solution and the inventive concept of the present application within the technical range disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. A method for preparing a low surface tension defoamer containing a fluorinated surfactant, characterized in that, Includes the following steps: Prepare the following raw materials by weight: 3-8 parts modified fluorinated hydrophobic silica, 15-30 parts perfluorinated polyether oil, 1-5 parts fluorinated surfactant, 1-3 parts organosilicon emulsifier, 0.2-1 parts thickener, and 50-80 parts deionized water. Step (1): Add the modified fluorinated hydrophobic silica to the perfluorinated polyether oil and disperse it at 50~60℃ to obtain a uniform oily slurry; The preparation process of the modified fluorinated hydrophobic silica includes the following steps: Step (1-1) Dry the fumed silica powder to remove moisture; In steps (1-2), by weight, 5 parts of dried fumed silica are added to 35-50 parts of heptane for dispersion. Under stirring, perfluorooctyltriethoxysilane modifier is slowly added dropwise until the amount added is 0.4-0.6 parts, and the addition time is ≥10 min. After the addition is complete, the mixture is refluxed at 96-100℃ for 12-24 h, cooled to room temperature, the solid product is separated, washed and dried to obtain modified fluorinated hydrophobic silica. The specific surface area of ​​the fumed silica powder is 150~300 m². 2 / g; Step (2): Cool the oily slurry obtained in step (1) to 30~40℃, add fluorinated surfactant and organosilicon emulsifier in sequence, and ultrasonically treat to obtain premixed emulsion. Under stirring conditions, slowly add 40%-80% of the total water addition amount of deionized water to the premixed emulsion, and stir evenly to obtain crude emulsion. Step (3): Transfer the crude emulsion obtained in step (2) to a sand mill and circulate it for 2 to 4 times at a speed of 1200-1500 revolutions per minute, while controlling the grinding temperature to ≤35℃; Step (4): Cool the emulsion obtained in step (3) after sand milling to 25~30℃, add the remaining deionized water and thickener, and stir evenly at a speed of 200~400r per minute to obtain a low surface tension defoamer containing fluorinated surfactant.

2. The method for preparing the low surface tension defoamer of the fluorinated surfactant according to claim 1, characterized in that, The perfluoropolyether oil has a number average molecular weight of 5000-6000 and a dynamic viscosity of 100-200 mPa·s at 25°C.

3. The method for preparing the low surface tension defoamer of the fluorinated surfactant according to claim 1, characterized in that, The fluorinated surfactant is perfluorinated (2-methyl-3-oxahexanoic acid); the organosilicon emulsifier is polyether-modified polydimethylsiloxane; and the thickener is hydrophobically modified hydroxyethyl cellulose.

4. The method for preparing the low surface tension defoamer of the fluorinated surfactant according to claim 1, characterized in that, The ultrasonic treatment in step (2) has a power of 300~1000W and a frequency of 20~40kHz. It is performed intermittently and the total time is 5~20min.

5. The method for preparing the low surface tension defoamer of the fluorinated surfactant according to claim 4, characterized in that, The intermittent processing time is 3-6 seconds for the working process and 1-2 seconds for the intermittent process.

6. The method for preparing the low surface tension defoamer of the fluorinated surfactant according to claim 1, characterized in that, In step (3), the single grinding time of the cyclic grinding is 5-10 min.

7. The method for preparing the low surface tension defoamer of the fluorinated surfactant according to claim 1, characterized in that, In step (4), after the stirring is completed, the product needs to be filtered with a 200-400 mesh filter.

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