A polyurethane-polyvinylidene fluoride hybrid emulsion and a preparation method thereof

Abstract

The present application relates to a kind of polyurethane and PVDF hybrid emulsion, comprising the following raw materials: polyurethane water dispersion, vinylidene fluoride monomer, initiator, chain transfer agent, the polyurethane water dispersion includes the following raw materials: polyisocyanate, multifunctional polymer, compound A containing 1 or more hydroxyl and 1 or more carboxyl, and total functionality ≥3, catalyst, neutralizing agent, water;Vinylidene fluoride monomer is inhaled into the closed container with polyurethane water dispersion, under pressure condition, in situ polymerization is obtained polyvinylidene fluoride in the presence of initiator and chain transfer agent, polyvinylidene fluoride and polyurethane form interpenetration and entanglement.The hybrid emulsion provided by the present application has excellent stability, which combines the chemical corrosion resistance of PVDF and the film-forming property of PU.VDF monomer is gaseous small molecule, easy to enter the inside of PU polymer, and in situ polymerization under pressure condition around PU polymer, form PVDF molecular chain and PU form molecular level interpenetration and / or entanglement.

Description

TECHNICAL FIELD

[0001] The present application relates to a polyurethane and polyvinylidene fluoride hybrid emulsion and a preparation method thereof. BACKGROUND

[0002] Polyvinylidene fluoride (PVDF) emulsion is widely used in the coating industry due to its excellent chemical corrosion resistance, especially in building exterior wall coatings and heavy industry coatings that require extremely high durability. However, the high-temperature baking film forming process of PVDF emulsion increases the processing difficulty and may result in insufficient flexibility after film formation, prone to cracking. In contrast, polyurethane emulsion is known for its excellent low-temperature film forming property, flexibility and elasticity, although its chemical resistance is poor. The hybrid emulsion of PU / PVDF obtained by seed emulsion polymerization / swelling polymerization process can combine the advantages of these two materials at the molecular level and nanoscale, providing a more excellent coating solution for multiple industries. This hybrid emulsion combines the chemical corrosion resistance of PVDF and the film forming property of PU, indicating a wide application prospect.

[0003] Patent CN118421144A combines polyvinylidene fluoride emulsion and water-based polyurethane emulsion together by simple mixing to prepare a hybrid emulsion of polyurethane (PU) and PVDF, which is applied to water-based thermal insulation coatings for railway bridge concrete surface protection. However, this hybrid emulsion prepared by blending is difficult to achieve uniform distribution of the two components during film formation, and it is difficult to combine and exert the advantages of the two materials.

[0004] Patent CN115433512A combines PVDF powder and polyurethane together by simple mixing to prepare an oil-based one-component polyurethane coating, which is applied to metal corrosion protection. However, this coating contains a large amount of VOC, has high carbon emissions and pollutes the environment.

[0005] In existing reports, the idea of first polymerization and then blending is often used to obtain a mixture of PU raw materials and PVDF raw materials. Given the low surface energy of fluorine-containing polymers and the different film forming and crystallization behaviors of different polymers, such blends are prone to problems such as delamination, sedimentation and difficulty in film formation. The present application introduces VDF monomers after PU polymerization by seed emulsion polymerization method. VDF monomers are gaseous small molecules that can easily enter the interior of PU polymers and form a certain concentration around the PU polymers under certain pressure conditions, initiating polymerization to form PVDF molecular chains in situ and forming molecular-level interpenetration and entanglement with PU. SUMMARY

[0006] An object of the present application is to provide a polyurethane and PVDF hybrid emulsion, which has both the chemical corrosion resistance of PVDF and the film-forming property of PU; the hybrid emulsion has a structure with a polyurethane shell and a PVDF core. When film-forming, the polyurethane shell can provide excellent film-forming property; after film-forming, the polyurethane phase and the PVDF phase can be uniformly distributed on a nanometer scale, so as to fully combine and exert the advantages of polyurethane and PVDF. Unlike the prior art, the hybrid emulsion of the present application avoids using an external emulsifier, thereby avoiding the negative influence of the external emulsifier on the performance after film-forming.

[0007] To achieve the above object, the technical scheme adopted by the present application is as follows:

[0008] The present application provides a polyurethane and PVDF hybrid emulsion, which comprises the following raw materials: a polyurethane water dispersion, a vinylidene fluoride monomer, an initiator, a chain transfer agent, wherein the polyurethane water dispersion comprises the following raw materials: a polyisocyanate, a multifunctional polymer, a compound A containing one or more hydroxyl groups and one or more carboxyl groups, and a total functionality of ≥3, a catalyst, a neutralizing agent, and water; the multifunctional polymer contains two or more groups capable of reacting with isocyanate; the vinylidene fluoride monomer is introduced into a sealed container containing the polyurethane water dispersion, and in-situ polymerization is carried out under the presence of the initiator and the chain transfer agent under pressurized conditions to obtain polyvinylidene fluoride, and the polyvinylidene fluoride and the polyurethane form interpenetration and / or entanglement.

[0009] Further, the polyurethane and PVDF hybrid emulsion comprises the following raw materials by weight: 40-60 parts of the polyurethane water dispersion, 40-60 parts of the vinylidene fluoride monomer, 0.1-1 part of the initiator, and 0.02-0.2 part of the chain transfer agent.

[0010] Further, the pressurized conditions are that the vinylidene fluoride gas is introduced to make the pressure of the sealed container 1.5-3 MPa, such as 2 MPa.

[0011] Further, the polyisocyanate is selected from at least one of aromatic, alicyclic, and aliphatic diisocyanates, including but not limited to α,α,α,α-tetramethylxylene diisocyanate (THXDI TM, 3,5,5-trimethyl-1-isocyanato-3-isocyanatomethylcyclohexane, isophorone diisocyanate (IPDI) and its derivatives, tetramethylene diisocyanate, hexamethylene diisocyanate (HDI) and its derivatives, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, isophorone diisocyanate, m-isopropenyl-alpha, alpha,-dimethylbenzyl isocyanate (TMI), 4,4'-dicyclohexylmethane diisocyanate (H12MDI), benzene-1,3-di(1-isocyanato-1-methylethyl), 1,5-naphthalene diisocyanate (NDI), p-phenylene diisocyanate (PPDI), trans-cyclohexane-1,4-diisocyanate (TMI), toluene diisocyanate (TODI), 4,4'-diphenylmethane diisocyanate, 4,4'-diphenyl dimethylmethane diisocyanate, di- and tetra-alkyldiphenylmethane diisocyanates, 4,4'-dibenzyl diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, toluene diisocyanate isomers, 1-methyl-2,4-diisocyanatocyclohexane, 1,6-diisocyanato-2,2,4-trimethylhexane, 1,6-diisocyanato-2,4,4-trimethylhexane.

[0012] Further, the polyfunctional polymer is selected from at least one of polyols, polyamines, polythiols, polyalcohol amines, and the number average molecular weight of the polyfunctional polymer is 500-3000 g / mol. Preferably, 1000-2000 g / mol. Further, the polyol is selected from at least one of polyether polyols, polyester polyols, polycarbonate polyols. Preferably, polyether polyols such as polyethylene glycol, polypropylene glycol, polybutylene glycol, polytetrahydrofuran, poly(propylene oxide) glycol.

[0013] Further, the compound A containing 1 or more hydroxyl groups and 1 or more carboxyl groups, and the total functionality is ≥3, is selected from at least one of di(hydroxymethyl)propionic acid, di(hydroxymethyl)butyric acid, 3-hydroxyglutaric acid, malic acid, tartaric acid.

[0014] Further, the catalyst is selected from at least one of organotin, organobismuth, tertiary amine, morpholine derivatives, piperazine derivatives. For example, the organotin is selected from dibutyltin dilaurate, stannous octoate, dibutyltin dichloride; the tertiary amine is selected from triethylamine, tripropylamine, monoethyldipropylamine, monoethyldibutylamine, diethylmonopropylamine, diethylmonobutylamine. The amount of catalyst is 0.1-1 wt% of the mass of the polyisocyanate.

[0015] Further, the neutralizing agent is inorganic base or organic base, such as sodium hydroxide, potassium hydroxide, tertiary amine, pyridine. The amount of neutralizing agent is to make the pH of the polyurethane aqueous dispersion 7-10.

[0016] Further, the solid content of the polyurethane aqueous dispersion is 30-45 wt%, preferably 38-42 wt%; wherein the amount of the polyisocyanate, the multifunctional polymer and the compound A satisfies the ratio of the amount of substance of the isocyanate groups (-NCO) in the polyisocyanate to the total amount of substance of the functional groups (hydroxyl, amine, thiol) in the multifunctional polymer and the compound A which can react with the isocyanate is 2-10. And the ratio of the number of active functional groups of the multifunctional polymer to the number of active functional groups of the compound A is 10:1-3. The active functional group is defined as the group which can react with the isocyanate, such as hydroxyl, carboxyl, amine, thiol.

[0017] Alternatively, the mass ratio of the polyisocyanate, the multifunctional polymer and the compound A is 150-235:231-305:26-42.

[0018] Further, the initiator is selected from organic initiators and / or inorganic initiators. The organic initiator is selected from diethyl peroxdicarbonate, diisopropyl peroxdicarbonate, di-n-propyl peroxdicarbonate, di-t-butyl peroxdicarbonate, di-t-butyl peroxide, t-butyl peroxypivalate, dicyclohexyl peroxdicarbonate, dicumyl peroxide and t-butyl hydroperoxide or a mixture of two or more thereof. The inorganic initiator is selected from potassium persulfate, sodium persulfate, ammonium persulfate or a mixture of two or more thereof.

[0019] Further, the chain transfer agent is selected from HCFC-123, CFC-11, DEC, DEM, isopropyl alcohol, ethyl acetate, methanol, cyclopentane, chloroform, acetone or a mixture of two or more thereof.

[0020] The present application also provides a preparation method of the polyurethane and PVDF hybrid emulsion, comprising the following steps:

[0021] (S1) mixing the polyisocyanate, the multifunctional polymer, the compound A and the catalyst uniformly under an inert atmosphere, heating and keeping the temperature until the NCO content of the system no longer changes, cooling, adding water and a neutralizing agent, so that the solid content and the pH of the obtained polyurethane aqueous dispersion meet the requirements, i.e. the pH is 7-10 and the solid content is 30-45 wt%, preferably 38-42 wt%;

[0022] (S2) mixing the polyurethane aqueous dispersion, the chain transfer agent and the initiator uniformly in a sealed container, heating to above the initiation temperature of the initiator, introducing the vinylidene fluoride monomer into the system under pressurized conditions, fully reacting to obtain the polyurethane and PVDF hybrid emulsion.

[0023] Further, in step (S1), the temperature is raised to 80-120℃; in step (S2), the initiation temperature is determined by the initiator, such as 70-130℃, and the pressurized condition is that the pressure in the container is 1.5-3 MPa, such as 2 MPa, by introducing vinylidene fluoride monomer.

[0024] The polyurethane and PVDF hybrid emulsion provided by the present application has excellent stability, and integrates the chemical corrosion resistance of PVDF and the film forming property of PU. The VDF monomer is introduced after the PU polymerization by the seed emulsion polymerization method. The VDF monomer is a gaseous small molecule, which is easy to enter the inside of the PU polymer, and is polymerized in situ around the PU polymer under the pressurized condition, to form the PVDF molecular chain and the PU to form the molecular level interpenetration and entanglement. The efficient formation of the chain entanglement is an effective means to improve the hybrid mixing of the fluorine-containing resin and other resins, and is beneficial to improve the mechanical strength of the polymer composite system. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 is the TEM image, HAADF-STEM image and energy dispersive spectrum of the hybrid emulsion prepared in Example 1.

[0026] Figure 2 is the intensity distribution curve of the fluorine (F) and nitrogen (N) elements obtained from a single PVDF-PU composite latex nanoparticle in the sample of Example 3. DETAILED DESCRIPTION

[0027] In order to more clearly illustrate the present application, the present application will be further described below in conjunction with preferred embodiments. Those skilled in the art should understand that the specific description below is illustrative rather than limiting, and should not limit the protection scope of the present application.

[0028] In the case of illustrating and explaining the purpose of the present application by the following examples, the components of the composition are all illustrated by weight parts as the general standard. In the absence of special instructions, for the sake of simplicity, the "parts" described in the examples of the present application are all weight parts.

[0029] Example 1

[0030] (S1) Into a reaction vessel, 220 parts of diisocyanate TTXDI, 305 parts of poly(propylene oxide) glycol with a molecular weight of 1000, 42 parts of bis(hydroxymethyl)propionic acid and 0.26 parts of dibutyltin dilaurate catalyst were added at room temperature. The stirring was turned on to 200 rpm and the reaction mixture was heated to 80°C. The reaction mixture was kept in this temperature range until the free NCO did not change anymore. The reaction vessel temperature was reduced to 65°C and then 17 parts of triethylamine were added dropwise into the reaction vessel. This reaction mass was stirred for 15 minutes. 830 parts of deionized water were added dropwise to the reaction vessel within 30 minutes and stirred for 30 minutes after the addition was completed. The mass was cooled down to 35°C and a polyurethane aqueous dispersion was obtained.

[0031] (S2) Into a reaction vessel, 50 parts of the polyurethane aqueous dispersion, 0.02 parts of chain transfer agent isopropyl alcohol were added successively and stirred for 0.5 h. After the above mixture solution was heated to 80°C, 0.8 parts of initiator ammonium persulfate was added. Then, 50 parts of vinylidene fluoride monomer was started to be introduced and the pressure of the reaction vessel was controlled at 2 MPa, and the reaction was carried out for 2 h, and a stable polyurethane and polyvinylidene fluoride hybrid emulsion was obtained.

[0032] Figure 1 Figure 1 is a TEM image, HAADF-STEM image and energy dispersive spectroscopy of the hybrid emulsion prepared in Example 1, wherein (A) is a transmission electron microscope (TEM) image, (B) is a high-angle annular dark-field scanning transmission electron microscope (HAADF-STEM) image, (C) to (E) are element distribution maps obtained by energy dispersive spectroscopy (EDS) analysis: (C) is a carbon element distribution map, (D) is a fluorine element distribution map, and (E) is a nitrogen element distribution map. It can be seen that the nitrogen element is contributed by the polyurethane molecular chain, and the fluorine element is contributed by the PVDF molecular chain. The uniform distribution of F elements in the nanoparticles indicates that PVDF is the main body of the nanoparticles. The nitrogen element is distributed in the interior and outer layer of the nanoparticles, indicating that the polyurethane molecules can enter the interior of the PVDF nanoparticles by this polymerization method. At the same time, the nitrogen element has a higher distribution density in the outer layer of the nanoparticles, indicating that there is more polyurethane in the shell layer. This core-shell structure is confirmed by the TEM image.

[0033] The method provided by the application can form a molecular chain level blend compatibility of PVDF and PU, so that chain entanglement is formed, and 1) the crystallinity of PVDF is reduced, and the transparency of the film is improved; and 2) the film forming ability of the fluorine-containing resin is improved, and the adhesion is improved.

[0034] Example 2

[0035] (S1) At room temperature, add 151 parts of hexamethylene diisocyanate, 231 parts of poly(ethylene oxide) glycol with a molecular weight of 1000, 26 parts of bis(hydroxymethyl)propionic acid, and 0.2 parts of dibutyl tin dilaurate catalyst into a reaction kettle. Turn on the stirring to 200 rpm, and heat the reaction mixture to 80°C. Keep the reaction mixture in this temperature range until the wt% free NCO is between 2.5-3.2. Reduce the reaction kettle temperature to 65°C, then add 12 parts of triethylamine into the reaction kettle dropwise. Stir the reaction material for 15 minutes. Add 611 parts of deionized water into the reaction kettle dropwise within 30 minutes, and stir for 30 minutes after the dropwise addition is completed. Cool the material to 35°C, and the polyurethane aqueous dispersion is obtained.

[0036] (S2) Add 40 parts of the above polyurethane aqueous dispersion, 0.06 chain transfer agent isopropyl alcohol into the reaction kettle successively, and stir for 0.5 h. After the above mixed solution is heated to 70°C, add 1 part of initiator ammonium persulfate. Then, introduce 60 parts of vinylidene fluoride monomer, control the pressure at 2 MPa, and react for 2 h, and the stable polyurethane and polyvinylidene fluoride hybrid emulsion is obtained.

[0037] Example 3

[0038] (S1) At room temperature, add 151 parts of hexamethylene diisocyanate, 231 parts of poly(ethylene oxide) glycol with a molecular weight of 1000, 26 parts of bis(hydroxymethyl)propionic acid, and 0.2 parts of dibutyl tin dilaurate catalyst into a reaction kettle. Turn on the stirring to 200 rpm, and heat the reaction mixture to 80°C. Keep the reaction mixture in this temperature range until the wt% free NCO is between 2.5-3.2. Reduce the reaction kettle temperature to 65°C, then add 12 parts of triethylamine into the reaction kettle dropwise. Stir the reaction material for 15 minutes. Add 611 parts of deionized water into the reaction kettle dropwise within 30 minutes, and stir for 30 minutes after the dropwise addition is completed. Cool the material to 35°C, and the polyurethane aqueous dispersion is obtained.

[0039] (S2) Add 40 parts of the above polyurethane aqueous dispersion, 0.06 chain transfer agent isopropyl alcohol into the reaction kettle successively, and stir for 0.5 h. After the above mixed solution is heated to 70°C, add 1 part of initiator ammonium persulfate. Then, introduce 60 parts of vinylidene fluoride monomer, control the pressure at 2 MPa, and react for 2 h, and the stable polyurethane and polyvinylidene fluoride hybrid emulsion is obtained. Figure 2The intensity distribution curves of fluorine (F) and nitrogen (N) elements obtained from a single PVDF-PU composite latex nanoparticle in the sample of Example 3 are shown. The arrow marks inserted along the HAADF-STEM image show that F represents the distribution of PVDF and N represents the distribution of polyurethane, which can be seen to prove that polyurethane and PVDF are co-distributed in the entire nanoparticle without phase separation in the single nanoparticle, indicating that the molecular chains of the two are fully entangled. After the molecular chains of polyurethane are entangled, the crystallinity of PVDF decreases, and the transparency of the film increases. This method can also improve the surface energy of the fluororesin and improve the adhesion of the film.

[0040] Comparative Example 1

[0041] 50 parts of the polyurethane dispersion in Example 1 were mixed uniformly with 50 parts of PVDF by high-speed stirring.

[0042] Comparative Example 2

[0043] 60 parts of the polyurethane dispersion in Example 3 were mixed uniformly with 40 parts of PVDF by high-speed stirring.

[0044] Comparative Example 3

[0045] The other aspects are the same as in Example 1, except that no bis(hydroxymethyl)propionic acid is added in step (S2).

[0046] Application Example

[0047] The emulsions in the above examples and comparative examples were tested for the following properties, and the results are shown in Table 1.

[0048] The adhesion of the coating was tested in accordance with the relevant contents in standard GB / T 9286-2021.

[0049] The transparency of the coating was tested in accordance with the relevant contents in standard JC / T 235-2014.

[0050] The water resistance of the coating was tested in accordance with the relevant contents in standard GB / T 1733-93.

[0051] Table 1 Performance test of emulsion

[0052] Product Adhesion Transparency Water resistance PVDF crystallinity Example 1 0 grade 93 5 days whitening 40％ Example 2 0 grade 95 7 days whitening 41％ Example 3 0 grade 96 3 days whitening 39％ Comparative Example 1 2 grade 76 1 day whitening 47％ Comparative Example 2 1 grade 81 1 day whitening 47％ Comparative Example 3 1 grade 70 2 days whitening 47％

[0053] As can be seen from Table 1, the performance of the urethane and polyvinylidene fluoride hybrid emulsion of the application is compared from three aspects of adhesion, transparency and water resistance. Compared with the simple blended emulsion, the hybrid emulsion with the structure of polyurethane shell and polyvinylidene fluoride core has more excellent performance. This is due to the fact that the coating prepared from the structure of the hybrid emulsion can realize the full entanglement of the molecular chains of polyurethane and polyvinylidene fluoride, i.e. the method can realize the uniform blending of fluororesin and other resins.

[0054] The inventors surprisingly found that the polyurethane-polyvinylidene fluoride hybrid emulsion prepared according to the present application simultaneously achieved high transparency and significantly improved thermal stability. The high transparency can be attributed to the fact that the PVDF was polymerized in situ in the polyurethane aqueous dispersion, resulting in a decrease in crystallinity. The improved thermal stability is attributed to the fact that the polyurethane and PVDF molecular chains form sufficient chain entanglements. The chain entanglements increase the interaction forces and crosslinking density between the polymer chains, which results in a higher thermal stability of the polymer in the glassy state.

Claims

1. A polyurethane and PVDF hybrid emulsion, characterized in that, The product comprises the following raw materials: a polyurethane aqueous dispersion, vinylidene fluoride monomer, an initiator, and a chain transfer agent. The polyurethane aqueous dispersion comprises the following raw materials: a polyisocyanate, a multifunctional polymer, compound A containing one or more hydroxyl groups and one or more carboxyl groups, with a total functionality ≥3, a catalyst, a neutralizing agent, and water. The multifunctional polymer contains two or more groups capable of reacting with the isocyanate. The vinylidene fluoride monomer is introduced into a sealed container containing the polyurethane aqueous dispersion. Under pressure, in the presence of the initiator and the chain transfer agent, in-situ polymerization is carried out to obtain polyvinylidene fluoride. The polyvinylidene fluoride and the polyurethane form interpenetrating and / or entangled bonds. Compound A is selected from at least one of di(hydroxymethyl)propionic acid, di(hydroxymethyl)butyric acid, 3-hydroxyglutaric acid, malic acid, and tartaric acid. The multifunctional polymer is a polyol. The number-average molecular weight of the multifunctional polymer is 500-3000 g / mol.

2. The polyurethane and PVDF hybrid emulsion according to claim 1, characterized in that, It includes the following raw materials in parts by weight: 40-60 parts of polyurethane aqueous dispersion, 40-60 parts of vinylidene fluoride monomer, 0.1-1 parts of initiator, and 0.02-0.2 parts of chain transfer agent.

3. The polyurethane and PVDF hybrid emulsion according to claim 1, characterized in that, The pressurization condition is to introduce vinylidene fluoride gas to make the pressure in the sealed container 1.5-3 MPa.

4. The polyurethane and PVDF hybrid emulsion according to claim 1, characterized in that, The polyisocyanate is selected from at least one of aromatic diisocyanates, alicyclic diisocyanates, and aliphatic diisocyanates.

5. The polyurethane and PVDF hybrid emulsion according to claim 4, characterized in that, The polyisocyanate is selected from α,α,α,α-tetramethylxylene diisocyanate, isophorone diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, m-isopropenyl-α,α,-dimethylbenzyl isocyanate, 4,4'-dicyclohexylmethane diisocyanate, benzene-1,3-di(1-isocyanate-1-methylethyl), 1,5-naphthalene diisocyanate, p-phenylene diisocyanate, transcyclohexane-1,4-diisocyanate, bitoluene diisocyanate, 4,4'- At least one of the following: diphenylmethane diisocyanate, 4,4'-diphenyldimethylmethane diisocyanate, 4,4'-dibenzyl diisocyanate, 1,3-phenyl diisocyanate, 1,4-phenyl diisocyanate, toluene diisocyanate isomer, 1-methyl-2,4-diisocyanate cyclohexane, 1,6-diisocyanate cyclohexane, and 1,6-diisocyanate cyclohexane.

6. The polyurethane and PVDF hybrid emulsion according to claim 1, characterized in that, The multifunctional polymer has a number-average molecular weight of 1000-2000 g / mol.

7. The polyurethane and PVDF hybrid emulsion according to claim 6, characterized in that, The polyol is selected from at least one of polyether polyol, polyester polyol, and polycarbonate polyol.

8. The polyurethane and PVDF hybrid emulsion according to claim 6, characterized in that, The polyether polyols are selected from polyethylene glycol, polypropylene glycol, polybutane glycol, polytetrahydrofuran, and poly(propylene oxide) glycol.

9. The polyurethane and PVDF hybrid emulsion according to claim 1, characterized in that, The catalyst is selected from at least one of organotin, organobismuth, tertiary amine, morpholine derivative, and piperazine derivative; and / or The neutralizing agent is an inorganic or organic base, and the amount of neutralizing agent used is such that the pH of the polyurethane aqueous dispersion is 7-10.

10. The polyurethane and PVDF hybrid emulsion according to claim 9, characterized in that, The neutralizing agent is selected from sodium hydroxide, potassium hydroxide, tertiary amine, and pyridine.

11. The polyurethane and PVDF hybrid emulsion according to claim 9, characterized in that, Organotin is selected from dibutyltin dilaurate, stannous octoate, and dibutyltin dichloride.

12. The polyurethane and PVDF hybrid emulsion according to claim 9, characterized in that, The tertiary amine is selected from triethylamine, tripropylamine, monoethyldipropylamine, monoethyldibutylamine, diethyldipropylamine, and diethyldibutylamine.

13. The polyurethane and PVDF hybrid emulsion according to claim 9, characterized in that, The amount of catalyst used is 0.1-1 wt% of the mass of the polyisocyanate.

14. The polyurethane and PVDF hybrid emulsion according to claim 1, characterized in that, The solid content of the polyurethane aqueous dispersion is 30-45 wt%; the mass ratio of polyisocyanate, polyfunctional polymer and compound A is 150-235:231-305:26-42.

15. The polyurethane and PVDF hybrid emulsion according to claim 14, characterized in that, The solid content of the polyurethane aqueous dispersion is 38-42 wt%.

16. The polyurethane and PVDF hybrid emulsion according to claim 1, characterized in that, The initiator is selected from organic initiators and / or inorganic initiators; the organic initiator is selected from diethyl dicarbonate peroxide, diisopropyl dicarbonate peroxide, di-n-propyl dicarbonate peroxide, di-tert-butyl dicarbonate peroxide, di-tert-butyl dicarbonate peroxide, tert-butyl neopentanoate peroxide, dicyclohexyl dicarbonate peroxide, dicumyl peroxide and tert-butyl hydroperoxide or a mixture of two or more thereof; the inorganic initiator is selected from potassium persulfate, sodium persulfate, ammonium persulfate or a mixture of two or more thereof; and / or The chain transfer agent is selected from isopropanol, ethyl acetate, and methanol.

17. A method for preparing the polyurethane and PVDF hybrid emulsion according to any one of claims 1-16, characterized in that, Includes the following steps: (S1) Mix the polyisocyanate, polyfunctional polymer, compound A and catalyst evenly under an inert atmosphere, heat and keep the temperature for reaction until the NCO content of the system no longer changes, cool, and add water and neutralizing agent. (S2) In a sealed container, the polyurethane aqueous dispersion, chain transfer agent and initiator are mixed evenly, and the temperature is raised above the initiation temperature of the initiator. Vinylidene fluoride monomer is introduced into the system under pressure to allow for a full reaction and obtain a polyurethane and PVDF hybrid emulsion.

18. The preparation method according to claim 17, characterized in that, In step (S1), the temperature is raised to 80-120℃, the amount of neutralizing agent added is adjusted to make the pH 7-10, and the amount of water added is adjusted to make the solid content 38-42wt%; in step (S2), the initiation temperature is 70-130℃, and the pressurization condition is to introduce vinylidene fluoride monomer to make the pressure inside the container 1.5-3MPa.

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