Perfluoropolyether phosphoric acid, preparation method thereof and anti-fingerprint agent

Abstract

The invention relates to the field of anti-fingerprint agents, and particularly discloses perfluoropolyether phosphoric acid, a preparation method thereof and an anti-fingerprint agent. The preparation method of the perfluoropolyether phosphoric acid comprises the following steps: S1, carrying out ammonolysis reaction on perfluoropolyether monomethyl ester and trihydroxymethyl aminomethane to obtain an intermediate I; s2, carrying out phosphorylation reaction on the intermediate I and phosphorus oxychloride to obtain an intermediate II; and S3, hydrolyzing the intermediate II to obtain the perfluoropolyether phosphoric acid. The perfluoropolyether phosphoric acid prepared by the invention can form a P-O-M bond with a metal oxide, so that the adhesive force of an anti-fingerprint agent on metal and a metal oxide substrate is remarkably improved, and the antifouling property can be maintained for a long time; the perfluoropolyether phosphoric acid contains three phosphoric acid groups, so that the hydrophobic antifouling effect and the friction resistance of a coating after the anti-fingerprint agent is cured into a film can be further enhanced, the durability of the coating is improved, and the perfluoropolyether phosphoric acid is particularly suitable for the surfaces of metal and metal oxide substrates.

Description

A perfluorinated polyether phosphoric acid, its preparation method, and an anti-fingerprint agent Technical Field

[0001] This application relates to the field of anti-fingerprint agents, and more specifically, it relates to a perfluoropolyether phosphoric acid, its preparation method, and an anti-fingerprint agent. Background Technology

[0002] In the field of anti-fingerprint agents, with the continuous development of technology, their applications are becoming increasingly widespread, especially in electronic devices and metal products. Good anti-fingerprint agents can effectively improve product appearance, enhance user experience, reduce cleaning hassles caused by fingerprint residue, and extend product lifespan, resulting in significant market demand. For substrates such as metals and metal oxides, suitable anti-fingerprint protection is crucial, protecting the product surface from contamination while increasing its aesthetics and durability. Therefore, developing high-performance anti-fingerprint agents is an important research direction in this field.

[0003] Traditional anti-fingerprint coatings (AF) primarily consist of methoxy or ethoxysilane-modified perfluoropolyethers. These coatings utilize the reaction of methoxy or ethoxysilanes with the hydroxyl groups on the substrate to form Si-OM bonds, resulting in a monomolecular coating with excellent adhesion on the glass surface. However, when treating metal or metal oxide substrates, the silane groups exhibit weak adhesion to the metal oxide surface, leading to insufficient bonding and easy peeling, which negatively impacts product lifespan and performance.

[0004] Existing technologies attempt to improve adhesion by increasing crosslinking density, but these methods often sacrifice the flexibility and abrasion resistance of the film. For example, increasing the number of terminal siloxanes in the anti-fingerprint agent molecule from three to six causes the siloxanes to react not only with the substrate's hydroxyl groups but also to undergo hydrolysis and condensation reactions among themselves, increasing the number of crosslinking points in the film. Furthermore, this method does not alter the adhesion between the siloxanes and the substrate, and requires strict processing conditions, resulting in high costs. Therefore, there is an urgent need to develop an anti-fingerprint coating with high adhesion and excellent abrasion resistance, especially one particularly suitable for metal or metal oxide substrates. Summary of the Invention

[0005] To address the aforementioned technical problems, this application provides a perfluoropolyether phosphoric acid, its preparation method, and an anti-fingerprint agent.

[0006] In a first aspect, this application provides a method for preparing perfluoropolyether phosphoric acid, which adopts the following technical solution: A method for preparing perfluoropolyether phosphoric acid includes the following steps: S1, reacting perfluoropolyether monomethyl ester with tris(hydroxymethyl)aminomethane with ammonolysis to obtain intermediate I; S2, reacting intermediate I with phosphoric acid trichloride to obtain intermediate II; S3, hydrolyzing intermediate II to obtain perfluoropolyether phosphoric acid.

[0007] The structural formula of the perfluoropolyether monomethyl ester is Rf-COOCH3, the structural formula of intermediate I is Rf-CONHC(CH2OH)3, and the structural formula of intermediate II is Rf-CONHC(CH2OPOCl2)3. Rf is a perfluoropolyether group with the structural formula CF3CF2O(CF3CF2O). m (CF2O) n CF2-, where m and n are integers greater than 0.

[0008] As a preferred embodiment, the molar ratio of the perfluoropolyether monomethyl ester to tris(hydroxymethyl)aminomethane is 1:(1.6-2.2).

[0009] More preferably, the molar ratio of the perfluoropolyether monomethyl ester to tris(hydroxymethyl)aminomethane is 1:(1.6-2.0).

[0010] As a preferred embodiment, the reaction conditions for the ammonolysis reaction are: a temperature of 80-120℃ and a time of 8-24h.

[0011] In the scheme of this application, the ammonolysis reaction is carried out in a solvent.

[0012] As a preferred embodiment, the solvent includes one or more of m-difluorotoluene, ethyl nonafluorobutyl ether (Novec HFE 7200 manufactured by 3M), perfluoromethylcyclohexane, and hydrochlorofluorocarbon (Asahiklin AK-225).

[0013] As a preferred embodiment, the molar ratio of intermediate I to phosphorus oxychloride is 1:(3.0-3.5).

[0014] More preferably, the molar ratio of intermediate I to phosphorus oxychloride is 1:(3.0-3.2).

[0015] As a preferred embodiment, the phosphorylation reaction is carried out under the following conditions: temperature 0-25℃ and time 3-6h.

[0016] In the scheme of this application, the phosphorylation reaction is carried out in a diluent and anhydrous pyridine or triethylamine is used as an acid-binding agent.

[0017] As a preferred embodiment, the diluent comprises one or more of ethyl nonafluorobutyl ether (Novec HFE7200 manufactured by 3M), m-difluorotoluene, perfluorotoluene, and perfluorobutyltetrahydrofuran.

[0018] As a preferred embodiment, the specific process of the hydrolysis is as follows: intermediate II is cooled to ≤0℃, then ice water or saturated sodium bicarbonate solution is added, stirred for 1-2 hours, and then acidified to pH 1-2.

[0019] By adopting the above technical solution, this application first undergoes an ammonolysis reaction between perfluoropolyether monomethyl ester and tris(hydroxymethyl)aminomethane to graft three hydroxyl groups onto it. Then, it further undergoes a phosphorylation reaction with phosphorus oxychloride and hydrolysis to graft three phosphate groups onto it. This allows the final perfluoropolyether phosphoric acid to form POM bonds (M representing a metal atom) with metal oxides, significantly improving the adhesion of the anti-fingerprint agent to metal and metal oxide substrates and maintaining its anti-fouling properties for a long time. Furthermore, because this perfluoropolyether phosphoric acid contains three phosphate groups, it can greatly enhance the hydrophobic and anti-fouling effects and abrasion resistance of the coating after the anti-fingerprint agent has cured into a film, thereby improving the durability of the coating.

[0020] Specifically, the phosphate groups (usually PO3H2 or PO4) in the perfluoropolyether phosphoric acid of this application 3- The bonding mechanism between phosphate ester compounds and metal surfaces mainly involves chemisorption processes, especially on metal oxide surfaces (such as iron oxide, aluminum oxide, or zinc oxide). This bonding often forms POM bonds, which are coordination or covalent interactions that enhance the adhesion of phosphate ester compounds to metal substrates. Therefore, the perfluoropolyether phosphate compound Rf-CONHC(CH2OPO2H2)3 prepared in this application can firmly adhere to metal surfaces, forming a durable nanoscale coating.

[0021] Secondly, this application provides a perfluoropolyether phosphoric acid prepared by the above-mentioned preparation method, wherein the perfluoropolyether phosphoric acid has the structural formula shown in Formula I: Formula I: Rf-CONHC(CH2OPO(OH)2)3; wherein Rf is a perfluoropolyether group, and its structural formula is CF3CF2O(CF3CF2O). m (CF2O) n CF2-, where m and n are integers greater than 0.

[0022] By adopting the above technical solution, the perfluoropolyether phosphoric acid molecule of this application contains phosphate groups, which can form POM bonds with metal oxides, effectively improving the adhesion of the anti-fingerprint agent coating to metal and metal oxide substrates, maintaining anti-fouling properties for a long time, and having excellent hydrophobicity and wear resistance, making it particularly suitable for metal and metal oxide substrate surfaces.

[0023] Thirdly, the anti-fingerprint agent provided in this application adopts the following technical solution: an anti-fingerprint agent, wherein the raw materials used in the anti-fingerprint agent include the above-mentioned perfluoropolyether phosphoric acid.

[0024] As a preferred embodiment, the raw materials used in the anti-fingerprint agent also include a diluent.

[0025] As a preferred embodiment, the diluent comprises one or more of the following: hexafluoropropylene trimer, ethyl nonafluorobutyl ether (Novec HFE7200 manufactured by 3M), 1,1,1,2,2,3,4,5,5,5-decafluoro-3-methoxy-4-(trifluoromethyl)pentane (Novec HFE7300 manufactured by 3M), and C5-18-perfluoroalkane (PF-5058 manufactured by 3M).

[0026] As a preferred embodiment, the perfluoropolyether phosphoric acid accounts for 0.1-10.0 wt% of all raw materials used in the anti-fingerprint agent.

[0027] More preferably, the perfluoropolyether phosphoric acid accounts for 0.2-5.0 wt% of all raw materials used in the anti-fingerprint agent.

[0028] More preferably, the perfluoropolyether phosphoric acid accounts for 0.3-1.0 wt% of all raw materials used in the anti-fingerprint agent.

[0029] By adopting the above technical solution, this application mixes perfluoropolyether phosphoric acid with a diluent in a certain proportion, and then applies the mixture as a surface treatment layer to the surface of the substrate to be treated. Since the anti-fingerprint agent of this application forms a monomolecular film on the substrate, within a certain range, increasing the content of perfluoropolyether phosphoric acid helps improve the performance of the anti-fingerprint coating. However, excessively high content not only fails to further improve the coating's performance but also increases production costs.

[0030] The surface treatment layer described above can be formed using methods commonly used in the art, such as wet coating or vacuum deposition. Examples of wet coating methods include dip coating, spin coating, roll coating, and spray coating. Examples of vacuum deposition methods include physical vapor deposition and magnetron sputtering. The substrate is a metal substrate or a metal oxide substrate, preferably tinplate, aluminum, or 304 stainless steel.

[0031] The surface of the substrate is then dried and heated using methods commonly used in the art. The substrate covered with perfluoropolyether phosphoric acid is placed at a temperature exceeding 100°C, more preferably exceeding 120°C but not exceeding 200°C, and baked for a time exceeding 15 minutes, more preferably exceeding 20 minutes but not exceeding 60 minutes.

[0032] As a preferred option, bake at 150°C for 30 minutes.

[0033] In such a high-temperature environment, the phosphate group (PO3H2) represented by Formula I acts as an active site, reacting with the hydroxyl group (M-OH) or Lewis acid site (exposed metal cation) on the substrate surface. The oxygen atom (negatively charged) of the phosphate group electrostatically attracts the surface cation or hydrogen bond to combine with M-OH, forming a covalent POM bond. This bond energy is relatively high compared to Si-OM, which can provide excellent adhesion. Furthermore, the perfluoropolyether phosphate of this application contains three phosphate groups, allowing for multidentate or interlocking coordination, further improving adhesion and forming a nanoscale network coating.

[0034] The principle behind the above process is: PO3H2 + M-OH → PO3H-M-O + H2O. The heat energy from drying and heating can promote water evaporation, driving the equilibrium to the right.

[0035] In summary, this application has the following beneficial technical effects: 1. The perfluoropolyether phosphoric acid prepared by the method of this application can form POM bonds with metal oxides, which significantly improves the adhesion of the anti-fingerprint agent to metal and metal oxide substrates and can maintain anti-fouling properties for a long time; 2. The perfluoropolyether phosphoric acid prepared by the method of this application contains three phosphate groups, which can further enhance the hydrophobic and anti-fouling effect and abrasion resistance of the coating after the anti-fingerprint agent is cured into a film, thereby improving the durability of the coating; 3. The preparation method of the perfluoropolyether phosphoric acid of this application has simple process conditions and low production cost of anti-fingerprint agent, making it suitable for large-scale industrial production. Detailed Implementation

[0036] The present application will be further described in detail below with reference to the embodiments.

[0037] Unless otherwise specified, the raw materials used in this application are those that can be obtained through commercial channels.

[0038] <Example 1> A method for preparing perfluoropolyether phosphoric acid includes the following steps: S1, adding perfluoropolyether monomethyl ester and tris(hydroxymethyl)aminomethane in a molar ratio of 1:2 to a reactor containing m-di(trifluorotoluene) solvent, and reacting with ammonolysis at 80°C for 8 hours to obtain intermediate I; S2, adding intermediate I and phosphorus oxychloride in a molar ratio of 1:3.2 to a reactor containing ethyl nonafluorobutyl ether (Novec HFE 7200 manufactured by 3M) solvent, and adding triethylamine as an acid-binding agent, with a molar ratio of intermediate I to triethylamine of 1:1.5, and reacting with phosphorylation at 0°C for 3 hours to obtain intermediate II; S3, cooling intermediate II to 0°C, then adding ice water and stirring for 1 hour, and then acidifying with 1 mol / L hydrochloric acid to pH 1 to obtain perfluoropolyether phosphoric acid, with a yield of 85%.

[0039] <Example 2>A method for preparing perfluoropolyether phosphoric acid includes the following steps: S1, adding perfluoropolyether monomethyl ester and tris(hydroxymethyl)aminomethane in a molar ratio of 1:1.8 to a reactor containing m-di(trifluorotoluene) solvent, and reacting with ammonolysis at 100°C for 12 h to obtain intermediate I; S2, adding intermediate I and phosphorus oxychloride in a molar ratio of 1:3.1 to a reactor containing ethyl nonafluorobutyl ether (Novec HFE 7200 manufactured by 3M) solvent, and adding triethylamine as an acid-binding agent, with a molar ratio of intermediate I to triethylamine of 1:1.5, and reacting with phosphorylation at 5°C for 4 h to obtain intermediate II; S3, cooling intermediate II to 0°C, then adding saturated sodium bicarbonate solution and stirring for 1 h, and then acidifying with 1 mol / L hydrochloric acid to pH 1 to obtain perfluoropolyether phosphoric acid, with a yield of 83%.

[0040] <Example 3> A method for preparing perfluoropolyether phosphoric acid includes the following steps: S1, adding perfluoropolyether monomethyl ester and tris(hydroxymethyl)aminomethane in a molar ratio of 1:2 to a reactor containing m-di(trifluorotoluene) solvent, and reacting with ammonolysis at 120°C for 12 h to obtain intermediate I; S2, adding intermediate I and phosphorus oxychloride in a molar ratio of 1:3.2 to a reactor containing ethyl nonafluorobutyl ether (Novec HFE 7200 manufactured by 3M) solvent, and adding triethylamine as an acid-binding agent, with a molar ratio of intermediate I to triethylamine of 1:1.5, and reacting with phosphorylation at 10°C for 5 h to obtain intermediate II; S3, cooling intermediate II to 0°C, then adding ice water and stirring for 2 h, and then acidifying with 1 mol / L hydrochloric acid to pH 2 to obtain perfluoropolyether phosphoric acid, with a yield of 86%.

[0041] <Example 4> A method for preparing perfluoropolyether phosphoric acid includes the following steps: S1, adding perfluoropolyether monomethyl ester and tris(hydroxymethyl)aminomethane in a molar ratio of 1:1.7 to a reactor containing m-di(trifluoro)toluene solvent, and reacting with ammonolysis at 110°C for 20 h to obtain intermediate I; S2, adding intermediate I and phosphorus oxychloride in a molar ratio of 1:3.5 to a reactor containing ethyl nonafluorobutyl ether (Novec HFE 7200 manufactured by 3M) solvent, and adding triethylamine as an acid-binding agent, with a molar ratio of intermediate I to triethylamine of 1:1.5, and reacting with phosphorylation at 15°C for 6 h to obtain intermediate II; S3, cooling intermediate II to 0°C, then adding ice water and stirring for 1 h, and then acidifying with 1 mol / L hydrochloric acid to pH 1 to obtain perfluoropolyether phosphoric acid, with a yield of 82%.

[0042] <Example 5>A method for preparing perfluoropolyether phosphoric acid includes the following steps: S1, adding perfluoropolyether monomethyl ester and tris(hydroxymethyl)aminomethane in a molar ratio of 1:2.2 to a reactor containing m-di(trifluorotoluene) solvent, and reacting with ammonolysis at 100°C for 24 h to obtain intermediate I; S2, adding intermediate I and phosphorus oxychloride in a molar ratio of 1:3.0 to a reactor containing ethyl nonafluorobutyl ether (Novec HFE 7200 manufactured by 3M) solvent, and adding triethylamine as an acid-binding agent, with a molar ratio of intermediate I to triethylamine of 1:1.5, and reacting with phosphorylation at 25°C for 3 h to obtain intermediate II; S3, cooling intermediate II to 0°C, then adding ice water and stirring for 1 h, and then acidifying with 1 mol / L hydrochloric acid to pH 1 to obtain perfluoropolyether phosphoric acid, with a yield of 88%.

[0043] <Example 6> A method for preparing perfluoropolyether phosphoric acid includes the following steps: S1, adding perfluoropolyether monomethyl ester and tris(hydroxymethyl)aminomethane in a molar ratio of 1:1.6 to a reactor containing m-di(trifluorotoluene) solvent, and reacting with ammonolysis at 115°C for 22 h to obtain intermediate I; S2, adding intermediate I and phosphorus oxychloride in a molar ratio of 1:3.4 to a reactor containing ethyl nonafluorobutyl ether (Novec HFE 7200 manufactured by 3M) solvent, and adding triethylamine as an acid-binding agent, with a molar ratio of intermediate I to triethylamine of 1:1.5, and reacting with phosphorylation at 7°C for 4 h to obtain intermediate II; S3, cooling intermediate II to 0°C, then adding saturated sodium bicarbonate solution and stirring for 2 h, and then acidifying with 1 mol / L hydrochloric acid to pH 2 to obtain perfluoropolyether phosphoric acid, with a yield of 84%.

[0044] <Comparative Example 1> Perfluoropolyether monomethyl ester and 3-aminopropyltrimethylsilane were dispersed in ethyl nonafluorobutyl ether (Novec HFE 7200, manufactured by 3M) solvent at a molar ratio of 1:2 and reacted at 65°C for 4 hours to obtain a siloxane-modified perfluoropolyether. Compared with the product of Example 1, the product's terminal structure was modified by replacing three phosphate groups with three methoxy groups, as shown in the following structural formula: Rf-CONH–(CH2)3–Si(OCH3)3; where Rf has the structural formula CF3CF2O(CF3CF2O). m (CF2O) n CF2-.

[0045] <Comparative Example 2>Perfluoropolyether monomethyl ester and 3-aminopropyltriethoxysilane were dispersed in ethyl nonafluorobutyl ether (Novec HFE 7200, manufactured by 3M) at a molar ratio of 1:2 and reacted at 65°C for 4 hours to obtain a siloxane-modified perfluoropolyether. Compared with the product of Example 1, the product's terminal structure was modified by replacing three phosphate groups with three ethoxy groups, as shown in the following structural formula: Rf-CONH–(CH2)3–Si(OC2H5)3; where Rf has the structural formula CF3CF2O(CF3CF2O). m (CF2O) n CF2-.

[0046] <Performance Detection> The products obtained in the above examples and comparative examples were mixed with hexafluoropropylene trimer at a weight ratio of 0.4:99.6. The mixture was then uniformly sprayed onto the surface of the substrate and subsequently baked in an oven at 150°C for 30 minutes to cure into a film. The actual thickness of the film was approximately 10-30 nm. After standing for 2 hours, the performance was tested, and the results are shown in Table 1.

[0047] The performance tests include static water contact angle test, steel wool friction durability test, and dynamic friction coefficient test.

[0048] The static water contact angle is measured using an SDC-100 standard contact angle meter. 2 μL of water is dropped onto a horizontally placed substrate film using a microsyringe. A still image is captured 1 second after the water drop is added using a video microscope, and the static water contact angle is calculated from this image. The static water contact angle is measured at five different locations on the substrate, and the average value is calculated.

[0049] Steel Wool Friction Durability Test Method: Steel Wool (count #0000, size 5mm × 10mm × 10mm) is brought into contact with the substrate film layer, and a load of 1000g is applied. Under the applied load, the steel Wool is moved back and forth at a speed of 100mm / s, and one round trip is recorded as one cycle. The static water contact angle of the coating surface is measured after 3000 cycles.

[0050] Test method for dynamic friction coefficient: The dynamic friction coefficient is measured using an MXD-02 friction coefficient meter. A balance is used with paper as the friction medium. A pressure of 200g is applied and the paper moves uniformly for 50mm at a speed of 100mm / min on the substrate film layer. The dynamic friction coefficient is then calculated.

[0051] Table 1 Performance Test Results As can be seen from Table 1, the preparation methods of Examples 1-6 of this application yielded perfluoropolyether phosphoric acid with a high yield, specifically 82-88%. Meanwhile, the perfluoropolyether phosphoric acid prepared in Examples 1-6 of this application and the products prepared in Comparative Examples 1-2 were subjected to relevant performance tests. The test results showed that the coating formed by the perfluoropolyether phosphoric acid prepared in Examples 1-6 of this application had a high static water contact angle and a high dynamic friction coefficient, exhibiting excellent hydrophobic and antifouling effects and abrasion resistance. After repeated rubbing with steel wool, the static water contact angle of the coating remained above 100°. In contrast, the methoxy or ethoxy-modified perfluoropolyether compound coatings prepared in Comparative Examples 1 and 2 had a static water contact angle below 100° after repeated rubbing with steel wool. This indicates that the coatings formed by existing anti-fingerprint agents have weak adhesion to metal substrates and are damaged during steel wool rubbing. The perfluoropolyether phosphoric acid prepared in this application can maintain the antifouling properties of the anti-fingerprint agent coating for a long time, exhibiting superior adhesion and durability, and is particularly suitable for metal and metal oxide substrate surfaces.

[0052] The embodiments described in this specific implementation are preferred embodiments of this application and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A method for preparing perfluoropolyether phosphoric acid, characterized in that, Includes the following steps: S1. Ammonialysis reaction of perfluoropolyether monomethyl ester with tris(hydroxymethyl)aminomethane is carried out to obtain intermediate I; S2. Phosphorylation reaction of intermediate I with phosphorus oxychloride to obtain intermediate II; S3. Hydrolysis of intermediate II to obtain perfluoropolyether phosphoric acid.

2. The method for preparing perfluoropolyether phosphoric acid according to claim 1, characterized in that, The molar ratio of the perfluoropolyether monomethyl ester to tris(hydroxymethyl)aminomethane is 1:(1.6-2.2).

3. The method for preparing perfluoropolyether phosphoric acid according to claim 1, characterized in that, The reaction conditions for the ammonolysis reaction are: temperature 80-120℃, time 8-24h.

4. The method for preparing perfluoropolyether phosphoric acid according to claim 1, characterized in that, The molar ratio of intermediate I to phosphorus oxychloride is 1:(3.0-3.5).

5. The method for preparing perfluoropolyether phosphoric acid according to claim 1, characterized in that, The reaction conditions for the phosphorylation reaction are: temperature 0-25℃, time 3-6h.

6. The method for preparing perfluoropolyether phosphoric acid according to claim 1, characterized in that, The specific process of hydrolysis is as follows: intermediate II is cooled to ≤0℃, then ice water or saturated sodium bicarbonate solution is added, stirred for 1-2 hours, and then acidified to pH 1-2.

7. A perfluoropolyether phosphoric acid prepared by the method for preparing perfluoropolyether phosphoric acid according to any one of claims 1-6, characterized in that, The perfluoropolyether phosphoric acid has the structural formula shown in Formula I: Formula I: Rf-CONHC(CH2OPO(OH)2)3; wherein, Rf is a perfluoropolyether group with the structural formula CF3CF2O(CF3CF2O). m (CF2O) n CF2-, where m and n are integers greater than 0.

8. An anti-fingerprint agent, characterized in that, The raw materials used in the anti-fingerprint agent include the perfluoropolyether phosphoric acid described in claim 7.

9. The anti-fingerprint agent according to claim 8, characterized in that, The perfluoropolyether phosphoric acid accounts for 0.1-10.0 wt% of all raw materials used in the anti-fingerprint agent.

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