CN118638267A - A fluoroether polymer and a protective coating agent containing the same - Google Patents

Abstract

The invention provides a fluoroether polymer and a protective coating agent containing the same, wherein the coating agent comprises the fluoroether polymer and a fluorine solvent, and the fluoroether polymer is obtained by free radical polymerization of a fluoroether acrylate monomer (A), an alkyl acrylate monomer (B) and an acrylate monomer (C) containing an aliphatic ring or an aromatic ring. The fluoroether polymer of the present invention can form a coating layer of a coating film having excellent water-proof and moisture-proof properties on various substrates, particularly electronic parts.

Description

A fluoroether polymer and a protective coating agent containing the same

Technical Field

The invention relates to the field of fluorine material preparation, and in particular to a fluoroether polymer and a protective coating agent containing the fluoroether polymer.

Background Art

Electronic coating agents are applied on the surface of electronic circuits to form a transparent protective film, which can protect the circuit board from damage in environments such as humidity, smoke, chemical corrosion, high dust, and vibration, thereby improving the reliability of the circuit board and the safety factor of the entire electronic component, thereby improving and extending their service life and ensuring safety and reliability in use.

Traditional electronic protective coating products are mostly polyurethane, epoxy resin, acrylic resin and silicone resin. However, the thickness of traditional protective coating is too high, which is not conducive to the heat dissipation of printed circuit boards (PCBs) during use, and the anti-fouling and moisture-proof properties are not outstanding. Fluorinated acrylates are considered to be the best PCB protective coating resins at present. Fluorinated acrylate polymers are obtained by introducing perfluorinated groups into acrylic polymers and changing the side chain structure of the original polymer. Due to the large electronegativity of fluorine, the C-F bond is very stable. At the same time, the perfluorinated side chains of the polymer are oriented outward, forming a "shielding protection" for the main chain and internal molecules, so that perfluorinated acrylate polymers have many excellent properties, such as good chemical inertness, weather resistance, anti-fouling, water and oil resistance, and UV resistance.

However, the existing perfluoroacrylate electronic protective agent coating is difficult to clean, and the protective coating may partially fall off or fail during substrate cutting and other processes. The introduction of perfluoropolyether groups can solve this problem, and it can be cleaned with environmentally friendly solvents. Chinese patent document CN109312031A provides a perfluoropolyether-based fluoroacrylate polymer, which is a permanent coating resin that can be used as a coating or additive, and can be used in anti-fouling in a variety of industries, and can also be used in the protection of flexible circuit boards. However, its slow film formation time and large thickness lead to the failure of the partial discharge effect of the circuit board, and the moisture-proof performance is gradually reduced.

Summary of the invention

The purpose of the present invention is to overcome the deficiencies of the prior art and provide a fluoroether polymer and a protective coating agent containing the polymer.

The polymer made by modifying the fluoroether acrylate polymer and replacing the long-chain fluoroalkyl chain with a fluoroether chain is used to prepare an electronic coating agent. The electronic coating agent has good high temperature resistance, salt spray resistance, acid and alkali resistance, as well as waterproof and moisture resistance, and has the advantages of fast volatilization and easy cleaning.

To achieve the above object, the technical solution adopted by the present invention is as follows:

A fluoroether polymer, wherein the fluoroether polymer is copolymerized by a fluoroether acrylate monomer (A), an alkyl acrylate monomer (B) and an acrylate monomer containing an aliphatic ring or an aromatic ring (C);

The monomer (A) has the following structure:

n = 1 to 5. Preferably, n = 2.

Preferably, the alkyl acrylate monomer (B) is selected from alkyl acrylates with a carbon number of 1 to 10 or alkyl acrylates with a carbon number of 1 to 10. The alkyl acrylate monomer (B) is further preferably methyl methacrylate (MMA).

Preferably, the aliphatic ring or aromatic ring-containing acrylate monomer (C) used in the present invention is selected from one or more of isobornyl methacrylate, benzyl methacrylate, and cyclohexyl methacrylate, and isobornyl methacrylate (IBOMA) is more preferred.

Preferably, the fluoroether polymer is polymerized by 75-95wt% of monomer (A), 1-20wt% of monomer (B) structural units and 1-15wt% of monomer (C). Further preferably, the fluoroether polymer is composed of 89-94wt% of monomer (A) structural units, 2-3wt% of monomer (B) structural units and 4-8wt% of monomer (C) structural units.

Preferably, the weight average molecular weight (Mw) of the fluoroether polymer is 50,000-200,000. More preferably, the weight average molecular weight (Mw) of the fluoroether polymer is 60,000-120,000, and more preferably 90,000-100,000. Too small a molecular weight of the fluoroether polymer leads to poor film-forming properties; too large a molecular weight of the fluoroether polymer leads to stacking of polymer molecules, which affects the performance of the film.

The present invention also provides a method for preparing the above-mentioned fluoroether polymer, comprising the following steps:

In the presence of a polymerization initiator, the polymerization monomers (A), (B), and (C) are dissolved in an organic solvent, and after nitrogen replacement, the mixture is heated and stirred at 30-120° C. for 1-20 hours, and the solvent is removed to obtain a fluoroether polymer. The process of removing the solvent can remove small molecular insolubles, which will affect moisture and rust resistance.

Preferably, the reaction temperature is 50-80° C., and the reaction time is 6-10 h; more preferably, the reaction temperature is 60-70° C., and the reaction time is 8-10 h.

Preferably, the polymerization initiator is an oil-soluble initiator selected from one or more of an azo initiator and a peroxide initiator; the azo initiator includes azobisisobutyronitrile or azobisisovaleronitrile, and the peroxide initiator includes benzophthalide peroxide, di-tert-butyl peroxide, lauryl peroxide, tert-butyl peroxypivalate or diisopropyl peroxydicarbonate. Azo initiators are further preferred.

Preferably, the polymerization initiator accounts for 0.05-2% of the total weight of all monomers.

Preferably, the organic solvent is a hydrofluoroether, specifically one or more of nC ₄ F ₉ OCH ₃ , nC ₄ F ₉ OCH ₂ CH ₃ , CF ₃ CF(CF ₃ )CF ₂ OCH ₃ , CF ₃ CF(CF ₃ )CF ₂ OCH ₂ CH ₃ , C ₈ F ₁₇ OCH ₃ , CH ₃ O(CF ₂ ) ₄ OCH ₃ , C ₅ F ₁₁ OC ₂ H ₅ , C ₃ F ₇ OCH ₃ , and (CF ₃ ) ₂ CFOCH _3. Further preferably, the organic solvent is perfluorohexyl methyl ether (HFE7300).

The present invention provides a protective coating agent comprising the above fluorinated ether compound, comprising 0.1-10 wt % of a fluorinated ether polymer and 90-99.9 wt % of an organic solvent. Preferably, the content of the fluorinated ether compound is 2-10 wt %.

The preparation method of the protective coating agent is as follows: diluting the fluoroether polymer with an organic solvent until the fluoroether polymer content is 0.1-10 wt %. The organic solvent is a hydrofluoroether, preferably perfluorobutyl ethyl ether (HFE7200).

In another aspect, the present invention provides use of the protective coating agent in printed circuit boards (PCBs), electrical equipment, semiconductors, sensors and hybrid circuits.

The method of use is: by dipping, spraying, foaming and other methods, the electronic coating agent is attached to the surface of the treated object, and it is naturally dried for 3 to 8 minutes to form a coating on the surface of the treated object. The thickness of the coating can be controlled at the micron or nanometer level by adjusting the content of the fluoroether polymer in the electronic coating agent. The dipping and dip coating treatment time is 10 to 35 seconds.

The present invention also provides a coating, which is prepared from the above fluoroether polymer, and has a thickness of 100-200 nm, a water contact angle of 114-116°, a hexadecane contact angle of 69-71°, a moisture resistance of less than 1100 g/m ² .day, an adhesion level of I-II, and a hardness of 2H-3H. The coating is suitable for substrates made of metal, glass, ceramic, plastic or composite materials.

Beneficial effects of the present invention:

One or more technical solutions provided by the specific implementation of the present invention have at least the following beneficial effects or advantages:

(1) The present invention uses fluoroether acrylate, alkyl acrylate monomers and acrylate monomers containing aliphatic rings or aromatic rings to copolymerize to obtain fluoroether polymers, which use fluoroether chains to replace traditional perfluoroalkyl chains, thereby not only improving the rust and moisture resistance, but also avoiding the damage of PFOA and FPOS to the human body and the environment.

(2) The electronic coating agent prepared from the fluoroether polymer provided by the present invention has excellent high temperature resistance and water, oil and dirt resistance.

(3) By adjusting the content of the fluoroether polymer in the protective coating agent, the present invention can make the coating thickness of the electronic coating agent on the material surface reach about 100 nm, forming an ultra-thin protective layer, which is beneficial to improving the dielectric constant and insulation of electronic products, and is particularly suitable for printed circuit boards, electronic components, electrical equipment and other fields.

(4) The electronic protective coating provided by the present invention takes into account the low surface energy, excellent weather resistance and heat resistance of fluororesin, as well as the good solubility and adhesion of acrylic resin, making the coating more durable and stable.

DETAILED DESCRIPTION

The present invention is further described below with reference to the examples, but the present invention is not limited thereto. All the raw materials used in the examples are commercially available or prepared using existing technologies.

Example 1

CH ₂ =C(CH ₃ )COOCH ₂ -CF(CF ₃ )O{CF ₂ CF(CF ₃ )O} ₂ CF ₂ CF ₂ CF ₃

(hereinafter referred to as methacrylic acid fluoroether monomer)/MMA/IBOMA=50/1.14/2.56 (weight ratio)

(1) 50 g of methacrylic acid fluoroether monomer, 1.14 g of methyl methacrylate (MMA), and 2.56 g of isobornyl methacrylate (IBOMA) were mixed to obtain a monomer mixture, and then the monomer mixture was added to 100 ml of perfluorohexyl methyl ether (HFE7300) in a nitrogen atmosphere, and 0.1 g of azobisisobutyronitrile (AIBN) was added, and the mixture was heated to 65° C. and stirred for reaction for 8 hours. After cooling to room temperature, the solvent was evaporated to dryness to obtain a fluoroether polymer. The weight average molecular weight (Mw) of the obtained fluoroether polymer was 90565, and the molecular weight distribution was 2.03.

(2) 5 g of fluoroether polymer and 95 g of perfluorobutyl ethyl ether (HFE7200) were stirred and mixed, and an electronic protective coating agent was obtained after the fluoroether polymer was completely dissolved.

Example 2

CH ₂ =C(CH ₃ )COOCH ₂ -CF(CF ₃ )O{CF ₂ CF(CF ₃ )O} ₂ CF ₂ CF ₂ CF ₃

/MMA/IBOMA=50/1.37/4.33 (weight ratio):

(1) 50 g of methacrylic acid fluoroether monomer, 1.37 g of methyl methacrylate (MMA), and 4.33 g of isobornyl methacrylate (IBOMA) were mixed to obtain a monomer mixture, and then the monomer mixture was added to 100 ml of perfluorohexyl methyl ether (HFE7300) in a nitrogen atmosphere, and 0.1 g of azobisisobutyronitrile (AIBN) was added, heated to 65° C., stirred for reaction for 10 hours, cooled to room temperature, and the solvent was evaporated to dryness to obtain a fluoroether polymer. The weight average molecular weight (Mw) of the obtained fluoroether polymer was 96800, and the molecular weight distribution was 2.33.

(2) 5 g of fluoroether polymer and 95 g of perfluorobutyl ethyl ether (HFE7200) were stirred and mixed, and an electronic protective coating agent was obtained after the fluoroether polymer was completely dissolved.

Example 3

CH ₂ =C(CH ₃ )COOCH ₂ -CF(CF ₃ )O{CF ₂ CF(CF ₃ )O} ₂ CF ₂ CF ₂ CF ₃

/MMA/IBOMA=50/3.03/6.67 (weight ratio):

(1) 50 g of methacrylic acid fluoroether monomer, 3.03 g of methyl methacrylate (MMA), and 6.67 g of isobornyl methacrylate (IBOMA) were mixed to obtain a monomer mixture, and then the monomer mixture was added to 100 ml of perfluorohexyl methyl ether (HFE7300) in a nitrogen atmosphere, and 0.1 g of azobisisobutyronitrile (AIBN) was added, heated to 50° C., stirred for reaction for 6 hours, cooled to room temperature, and the solvent was evaporated to dryness to obtain a fluoroether polymer. The weight average molecular weight (Mw) of the obtained fluoroether polymer was 122800, and the molecular weight distribution was 2.36.

(2) 5 g of fluoroether polymer and 95 g of perfluorobutyl ethyl ether (HFE7200) were stirred and mixed, and an electronic protective coating agent was obtained after the fluoroether polymer was completely dissolved.

Example 4

CH ₂ =C(CH ₃ )COOCH ₂ -CF(CF ₃ )O{CF ₂ CF(CF ₃ )O} ₂ CF ₂ CF ₂ CF ₃

/MMA/IBOMA=50/6.70/6.00 (weight ratio):

(1) 50 g of methacrylic acid fluoroether monomer, 6.7 g of methyl methacrylate (MMA), and 6.00 g of isobornyl methacrylate (IBOMA) were mixed to obtain a monomer mixture, and then the monomer mixture was added to 100 ml of perfluorohexyl methyl ether (HFE7300) in a nitrogen atmosphere, and 0.1 g of azobisisobutyronitrile (AIBN) was added, and the mixture was heated to 80° C. and stirred for 10 hours. After cooling to room temperature, the solvent was evaporated to dryness to obtain a fluoroether polymer. The weight average molecular weight (Mw) of the obtained fluoroether polymer was 131300, and the molecular weight distribution was 2.23.

(2) 5 g of fluoroether polymer and 95 g of perfluorobutyl ethyl ether (HFE7200) were stirred and mixed, and an electronic protective coating agent was obtained after the fluoroether polymer was completely dissolved.

Example 5

CH ₂ =C(CH ₃ )COOCH ₂ -CF(CF ₃ )O{CF ₂ CF(CF ₃ )O} ₂ CF ₂ CF ₂ CF ₃

/MMA/CHMA=50/1.14/2.56 (weight ratio):

(1) 50 g of methacrylic acid fluoroether monomer, 1.14 g of methyl methacrylate (MMA), and 2.56 g of cyclohexyl methacrylate were mixed to obtain a monomer mixture, and then the monomer mixture was added to 100 ml of perfluorohexyl methyl ether (HFE7300) in a nitrogen atmosphere, and 0.1 g of azobisisobutyronitrile (AIBN) was added, heated to 65° C., stirred for reaction for 8 hours, cooled to room temperature, and the solvent was evaporated to dryness to obtain a fluoroether polymer. The weight average molecular weight (Mw) of the obtained fluoroether polymer was 160400, and the molecular weight distribution was 2.53.

(2) 5 g of fluoroether polymer and 95 g of perfluorobutyl ethyl ether (HFE7200) were stirred and mixed, and an electronic protective coating agent was obtained after the fluoroether polymer was completely dissolved.

Comparative Example 1

CH ₂ =C(CH ₃ )COOCH ₂ -CF(CF ₃ )O{CF ₂ CF(CF ₃ )O} ₂ CF ₂ CF ₂ CF ₃

/IBOMA＝50/5 (weight ratio) polymer):

(1) 50 g of methacrylic acid fluoroether monomer and 5.0 g of isobornyl methacrylate (IBOMA) were mixed to obtain a monomer mixture, and then the monomer mixture was added to 100 ml of perfluorohexyl methyl ether (HFE7300) in a nitrogen atmosphere, and 0.1 g of azobisisobutyronitrile (AIBN) was added, heated to 65° C., stirred for reaction for 8 hours, cooled to room temperature, and the solvent was evaporated to dryness to obtain a fluoroether polymer. The weight average molecular weight (Mw) of the obtained fluoroether polymer was 100400, and the molecular weight distribution was 2.34.

(2) 5 g of fluoroether polymer and 95 g of perfluorobutyl ethyl ether (HFE7200) were stirred and mixed, and an electronic protective coating agent was obtained after the fluoroether polymer was completely dissolved.

Comparative Example 2

CH ₂ ＝C(CH ₃ )COOCH ₂ CH ₂ (CF ₂ ) ₄ CF ₂ CF ₃ /MMA＝50/8.6 (weight ratio) polymer):

(1) 50 g of 2-(perfluorohexyl)ethyl methacrylate and 8.6 g of isobornyl methacrylate (MMA) were mixed to obtain a monomer mixture, and then the monomer mixture was added to 100 ml of perfluorohexyl methyl ether (HFE7300) in a nitrogen atmosphere, and 0.1 g of azobisisobutyronitrile (AIBN) was added, heated to 65° C., stirred for reaction for 8 hours, cooled to room temperature, and the solvent was evaporated to dryness to obtain a fluoroether polymer. The weight average molecular weight (Mw) of the obtained fluoroether polymer was 98600, and the molecular weight distribution was 1.94.

(2) 5 g of fluoroether polymer and 95 g of perfluorobutyl ethyl ether (HFE7200) were stirred and mixed, and an electronic protective coating agent was obtained after the fluoroether polymer was completely dissolved.

Comparative Example 3

CH ₂ =C(CH ₃ )COOCH ₂ -CF(CF ₃ )O{CF ₂ CF(CF ₃ )O} ₂ CF ₂ CF ₂ CF ₃

/MMA=50/9.1 (weight ratio) polymer):

(1) 50 g of methacrylic acid fluoroether monomer and 9.1 g of methyl methacrylate (MMA) were mixed to obtain a monomer mixture, and then the monomer mixture was added to 100 ml of perfluorohexyl methyl ether (HFE7300) in a nitrogen atmosphere, and 0.1 g of azobisisobutyronitrile (AIBN) was added, heated to 65° C., stirred for reaction for 8 hours, cooled to room temperature, and the solvent was evaporated to dryness to obtain a fluoroether polymer. The weight average molecular weight (Mw) of the obtained fluoroether polymer was 118400, and the molecular weight distribution was 2.32.

(2) 5 g of fluoroether polymer and 95 g of perfluorobutyl ethyl ether (HFE7200) were stirred and mixed, and an electronic protective coating agent was obtained after the fluoroether polymer was completely dissolved.

Application performance testing:

(1) Static contact angle

The silicon wafer was ultrasonically cleaned in an acetone solution for 30 minutes and dried for later use as the object to be processed.

The fluoroether polymers prepared in the examples and comparative examples were diluted with a volatile fluorine-containing solvent (HFE7200) to an electronic protective coating agent with a mass fraction of 2%, and then the cleaned silicon wafer was immersed in the diluted protective coating agent, taken out after immersion for 30 seconds, and dried in the atmosphere for 30 minutes to obtain a test piece.

The contact angle test was conducted using a domestically produced CA100C contact angle tester with a droplet size of 2 μL. The contact angle data obtained were based on the average contact angles of three points on the sample surface. The results are shown in Table 1.

(2) Electrical properties

Tested with domestic dielectric constant meter:

1. Dissolve 1 g of the fluoroether polymer samples prepared in Examples 1-5 and Comparative Examples 1-3 in 9 g of 7300 solvent and stir until completely dissolved to prepare a protective coating agent with a fluoroether polymer content of 10 wt%.

2. Grind a copper sheet with a diameter of 3.8 cm to make its surface smooth and complete, and measure the thickness of the copper sheet.

3. Apply the prepared solution evenly on the copper sheet and let it dry naturally.

4. Measure the thickness of the copper sheet again and calculate the film thickness.

5. Input the film thickness. After fully drying, add two electrodes to both sides of the film. Test at room temperature with a test frequency of 100 Hz to 1 MHz. The results are shown in Table 1.

(3) Rust resistance

Refer to JIS-Z2371 salt spray test method:

1. Using a copper plate as a substrate, the fluoroether polymers prepared in Examples 1-5 and Comparative Examples 1-3 were diluted with a volatile fluorinated solvent (HFE7200) to an electronic protective coating agent with a mass fraction of 2% and impregnated. After 30 seconds, the copper plate was taken out and allowed to air dry naturally for 5 minutes to form a film (film thickness of about 100 nm).

2. Prepare 5% sodium chloride saline solution.

3. Place the treated samples into the salt spray chamber strictly according to the operating instructions.

4. Evaluate the appearance after 48 hours using five levels: no change, O (better), X (good), XX (discoloration), and XXX (severe discoloration).

(4) Moisture resistance

Refer to JIS Z0208 test method:

1. Use filter membrane (10um) as blank test, first conduct blank test, the moisture permeability is 3500g/ ^m2 ·day.

2. The fluoroether polymers prepared in Examples 1-5 and Comparative Examples 1-3 were diluted with a volatile fluorinated solvent (HFE7200) to an electronic protective coating agent with a mass fraction of 2%, and the filter membrane was dip-coated. After 10 seconds, the filter membrane was taken out and the surface of the filter membrane was naturally air-dried for 5 minutes. Thus, a membrane (membrane thickness of about 100 nm) was prepared and the moisture permeability was measured.

3. The smaller the moisture permeability value, the better the moisture resistance.

(5) Coating adhesion

1. Refer to the test method of GBT9286-2021 Scratching test for paints and varnishes;

2. The fluoroether polymers prepared in Examples 1-5 and Comparative Examples 1-3 were diluted with a volatile fluorinated solvent (HFE7200) to form an electronic protective coating agent with a mass fraction of 2%. A 25 mm × 75 mm × 1 mm glass slide was thoroughly cleaned with ethanol, and after being completely dried, the electronic protective coating agent was applied at room temperature using a spray brush and allowed to dry for 24 hours.

3. Use a multi-blade tool to draw a grid pattern with a spacing of 1mm×1mm on the coating sample. There should be 6 or 11 scratches on each side, and then use a brush to brush away the chips. In this operation, the scratches made by the multi-blade tool should penetrate the coating film. Immediately stick the tape on the scratches on the coating film, and press it flat and firmly with a pen eraser or fine cloth. Quickly tear off the tape from the coating film and use a magnifying glass to observe the damage to the paint film on the scratches. Grade the adhesion as follows.

Level Ⅰ: The coating does not fall off at all;

Level II: coating shedding does not exceed 10%;

Grade III: coating shedding does not exceed 25%;

Grade IV: coating shedding does not exceed 50%

Grade V: More than 50% of the coating has fallen off.

(6) Coating hardness

1. Refer to the test method of "GB/T 6739-2006 Paint and varnish pencil method for determination of paint film hardness";

2. The fluoroether polymers prepared in Examples 1-5 and Comparative Examples 1-3 were diluted with a volatile fluorinated solvent (HFE7200) to form an electronic protective coating agent with a mass fraction of 2%. A 25 mm × 75 mm × 1 mm glass slide was thoroughly cleaned with ethanol, and after being completely dried, the electronic protective coating agent was applied at room temperature using a spray brush and allowed to dry for 24 hours.

3. First, grind the pen tip vertically on fine sandpaper (1000#), and then install it on the hardness tester. The slope is about 25mm. Place weights on the hardness tester, shake the machine to make a uniform motion, and visually check whether there are scratches on the surface of the paint film. You can replace the Chinese pencil according to whether the paint film is scratched. Or judge the hardness by adding weights. In general, the higher the hardness, the better the adhesion, and the better the wear resistance of the coating.

Table 1

It can be seen from Table 1 that, compared with Comparative Examples 1-3, the fluorine-containing ether polymers of the embodiments of the present invention have higher contact angles and better salt spray protection and electrical properties.

Claims (10)

1. A fluoroether polymer, characterized in that the fluoroether polymer is copolymerized by a fluoroether acrylate monomer (A), an alkyl acrylate monomer (B) and an acrylate monomer containing an aliphatic ring or an aromatic ring (C); The monomer (A) has the following structure: n＝1～5. 2. The fluoroether polymer according to claim 1, characterized in that the alkyl acrylate monomer (B) is selected from alkyl acrylates with a carbon number of 1 to 10 or alkyl acrylates with a carbon number of 1 to 10. The alkyl acrylate monomer (B) is more preferably methyl methacrylate. 3. The fluoroether polymer according to claim 1, characterized in that the aliphatic ring or aromatic ring-containing acrylate monomer (C) is selected from one or more of isobornyl methacrylate, benzyl methacrylate, and cyclohexyl methacrylate, and isobornyl methacrylate is more preferred. 4. The fluoroether polymer according to claim 1, characterized in that the fluoroether polymer is polymerized by 75-95wt% of monomer (A), 1-20wt% of monomer (B) structural units and 1-15wt% of monomer (C). 5. The fluoroether polymer according to claim 1, characterized in that the weight average molecular weight (Mw) of the fluoroether polymer is 50000-200000. More preferably, the weight average molecular weight (Mw) of the fluoroether polymer is 60000-120000. 6. The method for preparing the fluoroether polymer according to any one of claims 1 to 5, characterized in that it comprises the following steps: In the presence of a polymerization initiator, the polymerization monomers (A), (B) and (C) are dissolved in an organic solvent, replaced with nitrogen, heated and stirred at 30-120° C. for 1-20 h, and the solvent is removed to obtain a fluoroether polymer. 7. The preparation method according to claim 6, characterized in that the reaction temperature is 50-80°C and the reaction time is 6-10 hours. 8. A protective coating agent comprising the fluoroether polymer according to any one of claims 1 to 5, characterized in that it comprises 0.1-10 wt% of the fluoroether polymer and 90-99.9 wt% of an organic solvent. 9. Use of the fluoroether polymer according to any one of claims 1 to 5 or the protective coating agent according to claim 7 in printed circuit boards, electrical equipment, semiconductors, sensors and hybrid circuits. 10. A coating, characterized in that the coating is prepared from the fluoroether polymer according to any one of claims 1 to 5, the coating has a thickness of 100 to 200 nm, a water contact angle of 114 to 116°, a hexadecane contact angle of 69 to 71°, and a moisture resistance of less than 1100 g/ ^m2 ·day.