A method for preparing an aqueous fluorocarbon emulsion

Abstract

The application discloses a preparation method of water-based fluorocarbon emulsion, which comprises the following steps: S1, adding a surfactant into water-based fluorocarbon emulsion with a concentration of 40%-60% as it is, stirring and heating for more than 30 minutes to prepare a mixed emulsion, and keeping warm for standby; S2, dispersing the mixed emulsion and water through an ultrasonic microreactor to obtain treated water-based fluorocarbon emulsion; or dispersing the mixed emulsion into the ultrasonic microreactor alone, then adding water to dilute, and then adding an alkaline solution to adjust the pH value to obtain the treated water-based fluorocarbon emulsion. In the application, the surfactant is added into the water-based fluorocarbon emulsion to increase the surface charge and the thickness of the surface adsorption layer of the emulsion droplets, so that the stability of the emulsion is enhanced; and the ultrasonic microreactor is used for dispersing treatment; the cavitation effect of ultrasonic waves of the ultrasonic microreactor in the liquid medium forms bubbles and rapidly closes, which generates local high temperature and high pressure, so that the particle size of fluorocarbon resin in the emulsion is reduced, the particle size is more uniform, and the dispersion stability is enhanced.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of water-based paint, and particularly discloses a preparation method of water-based fluorocarbon emulsion. BACKGROUND

[0002] Water-based fluorocarbon paint, also known as water-based fluorocarbon paint, is a durable water-based fluorocarbon paint with water-based fluorocarbon resin as the main component, which is a professional building wall durable water-based paint. Its coating on the surface of the object can form a protective film resistant to pollution, weathering and corrosion, and is widely used in building materials, industrial machinery, vehicles and ships, pharmaceutical packaging materials and other coating. Water-based fluorocarbon paint is a ceramic composite water-based fluorocarbon paint with 20 years of durability. It not only has durability of more than 20 years, but also is more conducive to environmental protection and energy saving due to its water solubility, and the cost is relatively more economical.

[0003] At present, the product generally has a solid content of 40-60% during the processing and production of water-based fluorocarbon paint, and has a high solid content and a large viscosity. In some scenes, it needs to be diluted to a lower concentration for use. However, the existing dilution process often causes uneven dilution and resin precipitation, which affects the coating effect of the paint and increases the loss. SUMMARY

[0004] In order to solve the problems in the prior art, the purpose of the present application is to provide a preparation method of water-based fluorocarbon emulsion, which aims to solve the technical problem that a large amount of fluorocarbon resin precipitates during dilution operation in the prior art.

[0005] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows: a preparation method of water-based fluorocarbon emulsion, comprising the following steps:

[0006] S1, adding a surfactant to a 40%-60% concentration water-based fluorocarbon emulsion, stirring and heating until fully mixed to obtain a mixed emulsion, and keeping warm for standby use;

[0007] S2, dispersing the mixed emulsion and water through an ultrasonic microreactor, then adding an alkaline solution to adjust the pH value of the emulsion to obtain a treated water-based fluorocarbon emulsion;

[0008] or the mixed emulsion is separately introduced into an ultrasonic microreactor for dispersion treatment, then water is added for dilution, and then an alkaline solution is added to adjust the pH value of the emulsion to obtain a treated water-based fluorocarbon emulsion.

[0009] In the present application, by adding surfactant to the 40%-60% concentration aqueous fluorocarbon emulsion, the surface charge and surface adsorption layer thickness of the emulsion droplets are increased to enhance the emulsion stability, and the dispersion treatment is carried out by an ultrasonic microreactor. The cavitation effect generated by the ultrasonic wave of the ultrasonic microreactor in the liquid medium forms bubbles and rapidly closes, which generates local high temperature and high pressure, thereby reducing the particle size of the fluorocarbon resin in the emulsion, making the particle size more uniform, enhancing the dispersion stability, and adjusting the ultrasonic power, ultrasonic time and other parameters of the ultrasonic microreactor to make the dilution process of the aqueous fluorocarbon emulsion controllable. While realizing the continuous preparation of low-concentration aqueous fluorocarbon emulsion, the unstable phenomena such as floating, precipitation, flocculation and coalescence are reduced, and the dispersion-stable low-concentration aqueous fluorocarbon emulsion is obtained.

[0010] Preferably, in the above preparation method, the dispersion treatment of the mixed emulsion and water by the ultrasonic microreactor is that the mixed emulsion and water are simultaneously introduced into the ultrasonic microreactor for dispersion treatment.

[0011] Or the mixed emulsion and water are first stirred and mixed, and then introduced into the ultrasonic microreactor for dispersion treatment.

[0012] Further preferably, in the above preparation method, the dispersion treatment of the mixed emulsion and water by the ultrasonic microreactor is that the mixed emulsion and water are simultaneously introduced into the ultrasonic microreactor for dispersion treatment. In this way, the problem of easy precipitation of resin can be avoided due to the dilution before ultrasonic dispersion treatment or the ultrasonic dispersion treatment before dilution, and the emulsion particle size and polydispersity index obtained by simultaneously introducing into the ultrasonic microreactor for dispersion treatment are better than the former two.

[0013] Preferably, in the above preparation method, when the ultrasonic microreactor is used for dispersion treatment, the ultrasonic power of the ultrasonic microreactor is 100-500 W, and the ultrasonic time is 1-5 min. When the ultrasonic dispersion treatment is carried out, the appropriate ultrasonic power and ultrasonic time can ensure good ultrasonic dispersion effect, and also can prevent the solvent from evaporating due to too large ultrasonic power and too long ultrasonic time, thereby affecting the concentration of the emulsion after dilution.

[0014] Preferably, in the above preparation method, the heating temperature in step S1 is 60-90℃. The appropriate temperature rise in step S1 can increase the resin flowability, reduce crystallization, and also can prevent the solvent from evaporating, thereby affecting the concentration of the emulsion after dilution.

[0015] Preferably, in the above preparation method, the stirring speed is 300-900 r / min.

[0016] Preferably, in the above preparation method, the mass ratio of the mixed emulsion to water in step S1 is (3-10):100, so as to dilute to the concentration of the commonly used aqueous fluorocarbon emulsion in actual use.

[0017] Preferably, in the above preparation method, the pH value in step S2 is 7-9, and the diluted emulsion has a suitable pH value, a small polydispersity index and high stability.

[0018] Preferably, in the above preparation method, the average particle size of the low-concentration aqueous fluorocarbon emulsion is less than 220 nm, the emulsion has good stability, and the solid content is 2%-5%.

[0019] Preferably, in the above preparation method, the surfactant is two to three kinds selected from non-ionic surfactants and anionic surfactants, such as Tween 20, 40, 60, 80, Span 20, 40, 60, 80, sodium dodecyl sulfonate and sodium dodecyl sulfate (SDS).

[0020] In the present application, the surfactant is a complex surfactant of non-ionic surfactants and anionic surfactants, and the purpose of the complex is to achieve additive and synergistic effects, that is, synergistic effects. That is, different types of surfactants are artificially mixed, and the performance of the mixture is better than that of the original single component, that is, the effect of "1+1>2". The non-ionic surfactant such as Tween can be combined with H2O and H3O+ through hydrogen bonds, so that the non-ionic surfactant has a part of positive charge, and therefore the interaction between the anionic surfactant and the non-ionic surfactant is relatively strong. Under a certain complex formula, the solubility of fluorocarbon resin can be improved.

[0021] Further preferably, the surfactant is Tween 80 and sodium dodecyl sulfate (SDS), and the mass ratio of the Tween 80 to the sodium dodecyl sulfate (SDS) is 15:1, so that the particle size of the obtained aqueous fluorocarbon emulsion after treatment is small, the polydispersity index is small, and the stability is good.

[0022] Preferably, in the above preparation method, the mass fraction of the surfactant is 3%-10% based on the mass of the aqueous fluorocarbon emulsion as it is, and more preferably 5%, and by setting a suitable amount of the surfactant, the dispersion effect and the stability can be ensured, and the coating effect of the coating material will not be affected due to the excessive amount of the surfactant.

[0023] Compared with the prior art, the present application has the following beneficial technical effects:

[0024] (1) The preparation method of the water-based fluorocarbon emulsion provided by the present application adds a surfactant to a 40%-60% concentration water-based fluorocarbon emulsion, increases the surface charge and surface adsorption layer thickness of the emulsion droplets to enhance the stability of the emulsion, and strengthens the dispersion treatment by coupling ultrasonic cavitation and microchannels in the ultrasonic microfluidic technology. The cavitation effect of the ultrasonic waves of the ultrasonic microreactor in the liquid medium forms bubbles and rapidly closes them. This process generates local high temperature and high pressure, thereby reducing the particle size of the fluorocarbon resin in the emulsion and making the particle size more uniform, enhancing the dispersion stability. By adjusting the ultrasonic power, ultrasonic time and other parameters of the ultrasonic microreactor, the dilution process of the water-based fluorocarbon emulsion can be controlled. The continuous preparation of low-concentration water-based fluorocarbon emulsion is realized, and the occurrence of unstable phenomena such as floating, precipitation, flocculation and coalescence is reduced, and a dispersion-stable low-concentration water-based fluorocarbon emulsion is obtained.

[0025] (2) The preparation method of the water-based fluorocarbon emulsion provided by the present application further improves the stability of the prepared low-concentration water-based fluorocarbon emulsion by adjusting the ratio and pH value of two or three surfactants, and reduces the precipitation. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 The particle size test results of Example 1;

[0027] Figure 2 The particle size test results of Example 2;

[0028] Figure 3 The particle size test results of Example 3. DETAILED DESCRIPTION

[0029] In order for those skilled in the art to better understand the present scheme, the present scheme will be further described in detail below in combination with specific examples. The process methods used in the examples are conventional methods unless otherwise specified; the materials used are commercially available unless otherwise specified.

[0030] Example 1

[0031] S1, under the condition of 80℃, 2.5g of surfactant of Tween 80, Span 80 (10:1) is added to 50g of water-based fluorocarbon emulsion, and stirred at a speed of 600r / min for 30 minutes, to obtain a mixed emulsion, which is kept for standby;

[0032] S2, 60 g of the mixed emulsion after treatment in step S1 was extracted by a syringe and connected with an ultrasonic microreactor and a syringe pump respectively, the ultrasonic time was set to 2 min, the power of the ultrasonic microreactor was 200 W; the syringe pump, the cooling fan and the ultrasonic power supply were turned on, and 3 min was waited before sample collection was started, about 20 g of sample was collected, then the sample collection was stopped, 2.5 g of the sample was diluted with 50 g of deionized water, and the pH value of the emulsion was adjusted to 8 by adding an appropriate amount of NaOH solution, to obtain the treated aqueous fluorocarbon emulsion A1.

[0033] Example 2

[0034] S1, 1.25 g of surfactant compounded by Tween 80 and Span 80 (10:1) was added to 2.5 g of the aqueous fluorocarbon emulsion under the condition of 80℃, and the mixed emulsion was prepared by stirring at a rate of 600 r / min for 30 min, and was kept for standby;

[0035] S2, 50 g of deionized water was added to the mixed emulsion in step S1 for dilution, then 60 g of the diluted mixed emulsion was extracted by a syringe and connected with an ultrasonic microreactor and a syringe pump respectively, the ultrasonic time was set to 2 min, the power of the ultrasonic microreactor was 200 W; the syringe pump, the cooling fan and the ultrasonic power supply were turned on, and 3 min was waited before sample collection was started, about 20 g of sample was collected, then the sample collection was stopped, and the pH value of the emulsion was adjusted to 8 by adding an appropriate amount of NaOH solution, to obtain the treated aqueous fluorocarbon emulsion A2.

[0036] Example 3

[0037] S1, 2.5 g of surfactant compounded by Tween 80 and SDS (15:1) was added to 50 g of the aqueous fluorocarbon emulsion under the condition of 80℃, and the mixed emulsion was prepared by stirring at a rate of 600 r / min for 30 min, and was kept for standby;

[0038] S2, 5 g of the mixed emulsion after treatment in step S1 was extracted by a syringe, 100 g of deionized water was extracted by another syringe, and they were connected with an ultrasonic microreactor and a syringe pump respectively, the flow rate ratio of the mixed emulsion to the deionized water was set to 5:100, the ultrasonic time was set to 2 min, the power of the ultrasonic microreactor was 300 W; the syringe pump, the cooling fan and the ultrasonic power supply were turned on, and 3 min was waited before sample collection was started, about 20 g of sample was collected, then the sample collection was stopped, and the pH value of the emulsion was adjusted to 8 by adding an appropriate amount of NaOH solution, to obtain the treated aqueous fluorocarbon emulsion A3.

[0039] Comparative Example 1

[0040] S1, 2.5g of the surfactant of Tween 80, SDS (15:1) was added into 50g of the original aqueous fluorocarbon emulsion at 80℃, and the mixture was stirred at a speed of 600r / min for 30min, and the emulsion was mixed and kept for standby;

[0041] S2, 5g of the treated emulsion in step S1 was taken by a syringe, and 100g of deionized water was taken by another syringe, which were respectively connected to the ultrasonic microreactor and the injection pump, and the flow rate ratio of the emulsion to the deionized water was set to 5:100, the ultrasonic time was 1min, the power of the ultrasonic microreactor was 300W, the injection pump, the cooling fan and the ultrasonic power supply were turned on, and the sample was collected after 2min, and the collection was stopped after about 20g of the sample was collected, and a small amount of NaOH solution was added to adjust the pH value of the emulsion to 8, to obtain the treated aqueous fluorocarbon emulsion B1.

[0042] Comparative Example 2

[0043] S1, 2.5g of the surfactant of Tween 80, SDS (15:1) was added into 50g of the original aqueous fluorocarbon emulsion at 80℃, and the mixture was stirred at a speed of 600r / min for 30min, and the emulsion was mixed and kept for standby;

[0044] S2, 5g of the treated emulsion in step S1 was taken by a syringe, and 100g of deionized water was taken by another syringe, which were respectively connected to the ultrasonic microreactor and the injection pump, and the flow rate ratio of the emulsion to the deionized water was set to 5:100, the ultrasonic time was 2min, the power of the ultrasonic microreactor was 30W, the injection pump, the cooling fan and the ultrasonic power supply were turned on, and the sample was collected after 3min, and the collection was stopped after about 20g of the sample was collected, and an appropriate amount of NaOH solution was added to adjust the pH value to 8, to obtain the treated aqueous fluorocarbon emulsion B2.

[0045] Comparative Example 3

[0046] S1, 2.5g of the surfactant of Tween 80, SDS (15:1) was added into 50g of the original aqueous fluorocarbon emulsion at 80℃, and the mixture was stirred at a speed of 600r / min for 30min, and the emulsion was mixed and kept for standby;

[0047] S2, 5g of the treated emulsion in step S1 was taken by a syringe, and 100g of deionized water was taken by another syringe, which were respectively connected to the ultrasonic microreactor and the injection pump, and the flow rate ratio of the emulsion to the deionized water was set to 5:100, the ultrasonic time was 2min, the power of the ultrasonic microreactor was 30W, the injection pump, the cooling fan and the ultrasonic power supply were turned on, and the sample was collected after 3min, and the collection was stopped after about 20g of the sample was collected, and an appropriate amount of NaOH solution was added to adjust the pH value to 8, to obtain the treated aqueous fluorocarbon emulsion B2.

[0048] Comparative Example 4

[0049] S1, 2.5g of the surfactant of Tween 80 and SDS (15:1) was added into 50g of the fluorocarbon emulsion, and the mixture was stirred at 80°C for 30 minutes at a speed of 600r / min to prepare a mixed emulsion, which was kept for standby;

[0050] S2, 5g of the mixed emulsion prepared in step S1 was taken by a syringe, and 100g of deionized water was taken by another syringe, which were respectively connected to the ultrasonic microreactor and the injection pump, and the flow rate ratio of the mixed emulsion to the deionized water was set to 5:100, the ultrasonic time was 2min, the power of the ultrasonic microreactor was 300W, and the injection pump, the cooling fan and the ultrasonic power were turned on, and after 3min, the sample was collected, and after about 20g of the sample was collected, the collection was stopped, and an appropriate amount of NaOH solution was added to adjust the pH value to 10, to obtain the treated fluorocarbon emulsion B4.

[0051] Comparative Example 5

[0052] S1, 0.5g of the surfactant of Tween 80 and SDS (15:1) was added into 50g of the fluorocarbon emulsion, and the mixture was stirred at 80°C for 30 minutes at a speed of 900r / min to prepare a mixed emulsion, which was kept for standby;

[0053] S2, 5g of the mixed emulsion prepared in step S1 was taken by a syringe, and 100g of deionized water was taken by another syringe, which were respectively connected to the ultrasonic microreactor and the injection pump, and the flow rate ratio of the mixed emulsion to the deionized water was set to 5:100, the ultrasonic time was 2min, the power of the ultrasonic microreactor was 30W, and the injection pump, the cooling fan and the ultrasonic power were turned on, and after 3min, the sample was collected, and after about 20g of the sample was collected, the collection was stopped, and an appropriate amount of NaOH solution was added to adjust the pH value of the emulsion to 8, to obtain the treated fluorocarbon emulsion B5.

[0054] Test performance

[0055] 1, the fluorocarbon resin in the fluorocarbon emulsion prepared in example 1-3 and the fluorocarbon emulsion A1-A3 prepared in comparative example 1-5 was not obviously precipitated after standing for two weeks, and the low-concentration fluorocarbon emulsion was stable, and the fluorocarbon resin in the fluorocarbon emulsion prepared in comparative example 1-5 was obviously precipitated, and the low-concentration fluorocarbon emulsion was unstable.

[0056] 2、Test the average particle size and polydispersity index of the original water-based fluorocarbon emulsion and the water-based fluorocarbon emulsion A1-A3 treated by Example 1-3, the water-based fluorocarbon emulsion B1-B5 treated by Comparative Example 1-5, the results are shown in Table 1, and the particle size test results of the water-based fluorocarbon emulsion A1-A3 treated by Example 1-3 are shown in Figure Figures 1-3 .

[0057] Table 1 Average particle size and polydispersity index (PDI) of examples and comparative examples

[0058] Sample Name Average Particle Size (nm) PDI Water-based fluorocarbon emulsion as is 226.0 0.104 Example 1 Treated water-based fluorocarbon emulsion A1 199.1 0.122 Example 2 Treated water-based fluorocarbon emulsion A2 189.3 0.159 Example 3 Treated water-based fluorocarbon emulsion A3 197.2 0.099 Comparative Example 1 Treated water-based fluorocarbon emulsion B1 208.6 0.185 Comparative Example 2 Treated water-based fluorocarbon emulsion B2 209.1 0.111 Comparative Example 3 Treated water-based fluorocarbon emulsion B3 212.8 0.211 Comparative Example 4 Treated water-based fluorocarbon emulsion B4 211.9 0.210 Comparative Example 5 Treated water-based fluorocarbon emulsion B5 217.7 0.104

[0059] From the data of Table 1 and Figure Figures 1-3 , it can be seen that the low-concentration water-based fluorocarbon emulsion A1-A3 obtained by treating the water-based fluorocarbon emulsion by Example 1-3 has an average particle size of less than 200 nm, a low polydispersity index, good dispersing effect, and high stability. Among them, Example 3 uses the method of simultaneously passing the mixed emulsion and water into the ultrasonic microreactor for dispersion treatment, and the obtained water-based fluorocarbon emulsion has a smaller average particle size, a smaller polydispersity index, and higher stability.

[0060] From the data of Comparative Example 3 and Comparative Example 1-2, it can be seen that when the ultrasonic time is short or the ultrasonic power is too small, the dispersing effect of the treated water-based fluorocarbon emulsion is not good, the average particle size and the polydispersity index are larger than those of Example 3, and the stability is much worse than that of Example 3.

[0061] From the data of Comparative Example 3 and Comparative Example 3, it can be seen that when only one kind of surfactant SDS is used, the dispersing effect is not good, the average particle size and the polydispersity index of the obtained water-based fluorocarbon emulsion are larger than those of Example 3, and the stability of the treated water-based fluorocarbon emulsion is poor.

[0062] From the data of Comparative Example 3 and Comparative Example 4, it can be seen that when too much water is added and the pH value of the emulsion is 10, the average particle size and the polydispersity index of the treated water-based fluorocarbon emulsion are larger than those of Example 3, and the stability of the treated water-based fluorocarbon emulsion is also relatively poor.

[0063] From the data of Comparative Example 3 and Comparative Example 5, it can be seen that when the amount of surfactant added is too small, the dispersing effect and the stability are both poor, the average particle size and the polydispersity index of the treated water-based fluorocarbon emulsion are larger than those of Example 3.

[0064] The protection scope of the present application is not limited by these specific examples, but is determined by the claims of the present application. For those skilled in the art, the scope of protection of the present application should not be deviated from the alternatives and modifications, and is covered by the rights of the present patent application.

Claims

1. A method for producing an aqueous fluorocarbon emulsion, characterized by, The method comprises the following steps: S1, adding a surfactant to an aqueous fluorocarbon emulsion with a concentration of 40%-60% as it is, stirring and heating for more than 30 minutes to obtain a mixed emulsion, and keeping it warm for standby; S2, dispersing the mixed emulsion and water through an ultrasonic microreactor, then adding an alkaline solution to adjust the pH value of the emulsion to obtain a treated aqueous fluorocarbon emulsion; Or separately passing the mixed emulsion into the ultrasonic microreactor for dispersion treatment, then adding water for dilution, and then adding an alkaline solution to adjust the pH value of the emulsion to obtain a treated aqueous fluorocarbon emulsion; When the ultrasonic microreactor is used for dispersion treatment, the ultrasonic power of the ultrasonic microreactor is 100-500 W, and the ultrasonic time is 1-5 min; The pH value in step S2 is 7-9; The surfactant is a non-ionic surfactant and an anionic surfactant, and the mass fraction of the surfactant in the aqueous fluorocarbon emulsion as it is is 3%-10%.

2. The method for preparing an aqueous fluorocarbon emulsion according to claim 1, characterized by, The dispersion treatment of the mixed emulsion and water through the ultrasonic microreactor is that the mixed emulsion and water are simultaneously passed into the ultrasonic microreactor for dispersion treatment. Or the mixed emulsion and water are first stirred and mixed, and then passed into the ultrasonic microreactor for dispersion treatment.

3. The method for preparing an aqueous fluorocarbon emulsion according to claim 2, characterized by, The dispersion treatment of the mixed emulsion and water through the ultrasonic microreactor is that the mixed emulsion and water are simultaneously passed into the ultrasonic microreactor for dispersion treatment.

4. The method for preparing an aqueous fluorocarbon emulsion according to claim 1, characterized by, The heating temperature in step S1 is 60-90℃, and the stirring speed is 300-900 r / min.

5. The method of claim 1, wherein the water-based fluorocarbon emulsion is prepared by the steps of: The mass ratio of the mixed emulsion to water in step S2 is (3-10):

100.

6. The method of claim 1, wherein the water-based fluorocarbon emulsion is prepared by the steps of: The surfactant is selected from two to three kinds of Tween 20, Tween 40, Tween 60, Tween 80, Span 20, Span 40, Span 60, Span 80, sodium dodecyl sulfonate, and sodium dodecyl sulfate.

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