A chain-functionalized perfluoropolyether and its preparation method

Abstract

The present invention provides a chain-functionalized perfluoropolyether and a preparation method thereof. The preparation method includes: S1, mixing a double-ended hydroxyl perfluoropolyether and an oxidation reagent, reacting at 60-120 °C for 1-72 h to obtain an oxidation product, and mixing the oxidation product with an alcohol to obtain a first intermediate product; S2, mixing an acetyl compound, a hydrogen abstraction reagent, and an ether solvent, reacting to obtain a second intermediate product containing a carbanion; S3, mixing the first intermediate product and the second intermediate product, reacting, and separating the product to obtain a chain-functionalized perfluoropolyether. The elastomer prepared from the chain-functionalized perfluoropolyether provided by the present invention has good low-temperature resilience.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer chemistry, and more particularly, relates to a chain-functionalized perfluoropolyether and a preparation method thereof. Background Art

[0002] In recent years, with the rapid development of intelligent devices, smart wearables, AI operations, AI home applications, intelligent express sorting, etc., the demand for high-end AI chips has been increasing. Chip manufacturing (etching, printing, editing) equipment requires high solvent-resistant and highly corrosion-resistant sealing materials, which are mainly perfluoroether rubber (FFKM). Since the glass transition temperature (T g ) of FFKM is around -30°C, its resilience is poor under low-temperature operating conditions, and it is expensive, which has always restricted its application in many fields. Therefore, it is necessary to add a polymer with a T g value less than -30°C and good compatibility with FFKM to improve the low-temperature performance of FFKM.

[0003] In the prior art, there is no clear solution to improve the low-temperature performance of FFKM. Recently, fluorine-containing elastomers with excellent low-temperature performance - perfluoropolyether (PFPE)-based elastomers have become a research hotspot. Obviously, using PFPE with a low T g value (-110°C to -50°C) can effectively improve the low-temperature performance of FFKM, and PFPE has high compatibility with FFKM and can be mixed and processed in any proportion.

[0004] European Patent Application EP 0195946A2 discloses a preparation method of terminal bromo PFPE and mentions that under the action of peroxide, this terminal bromo PFPE can co-vulcanize with fluororubber. The modified fluororubber becomes easier to process, the demoulding property and thermal stability of the product are improved, and its mechanical properties, compression set and solvent resistance are almost unchanged. However, terminal bromo PFPE can only be prepared during the production of raw materials, and due to the explosive characteristics of peroxy groups, the safety factor of the preparation is low and it is not suitable for industrialization. Summary of the Invention

[0005] In order to solve the above problems in the prior art, the object of the present invention is to provide a chain-functionalized perfluoropolyether and a preparation method thereof. The elastomer provided by the present invention has good low-temperature resilience.

[0006] To achieve the above object, according to the first aspect of the present invention, there is provided a preparation method of a chain-functionalized perfluoropolyether, which comprises:

[0007] S1, mixing a double-terminal hydroxyl perfluoropolyether, an oxidation reagent and a solvent, reacting to obtain an oxidation product, and mixing the oxidation product with an alcohol to obtain a first intermediate product;

[0008] S2. Mix an acetyl compound, a hydrogen abstraction reagent, and an ether solvent, and react to obtain a second intermediate product containing a carbanion.

[0009] S3. Mix the first intermediate product and the second intermediate product, carry out a reaction, and then separate the product to obtain the chain-functionalized perfluoropolyether.

[0010] The present invention first proposes the above route for preparing chain-functionalized perfluoropolyethers. By reacting a first intermediate product (perfluoropolyether ester) with a second intermediate product containing a carbanion, a chain-functionalized perfluoropolyether material with more crosslinking sites is prepared. The elastomer obtained after crosslinking has excellent properties at low temperatures.

[0011] In some preferred embodiments of the present invention, S1 includes a process of post-treating the first intermediate product, and S3 includes a process of post-treating the obtained functionalized perfluoropolyether. The above post-treatments respectively include suction filtration, washing, vacuum distillation, etc. Specific methods can be easily designed by those skilled in the art, and the present invention does not make further limitations here.

[0012] In some preferred embodiments of the present invention, the solvent in S1 includes water.

[0013] In some preferred embodiments of the present invention, in S1, the reaction temperature is 60 - 120 °C, and the time is 1 - 72 h.

[0014] In some preferred embodiments of the present invention, in S2, the reaction temperature is 0 - 60 °C, and the time is 0.2 - 5 h.

[0015] In some preferred embodiments of the present invention, in S3, the reaction temperature is 25 - 120 °C, and the time is 0.5 - 36 h.

[0016] In some preferred embodiments of the present invention, the average molecular weight of the bifunctional hydroxyl perfluoropolyether is 1000 - 10000.

[0017] In some preferred embodiments of the present invention, the alcohol includes methanol and / or ethanol.

[0018] In some preferred embodiments of the present invention, the bifunctional hydroxyl perfluoropolyether includes one or a combination of two or more of bifunctional hydroxyl K-type perfluoropolyether, bifunctional hydroxyl Y-type perfluoropolyether, and bifunctional hydroxyl Z-type perfluoropolyether.

[0019] In some preferred embodiments of the present invention, the acetyl compound includes one or a combination of two or more of ethyl haloacetate, methyl haloacetate, ethyl acetate, methyl acetate, haloacetone, acetone, ethyl halomalonate, methyl halomalonate, ethyl malonate, and methyl malonate.

[0020] In some preferred embodiments of the present invention, the oxidation reagent includes one or a combination of two or more of potassium permanganate, potassium dichromate, sodium dichromate, chromium trioxide, potassium peroxymonosulfate, nitric acid, oxygen, hydrogen peroxide, dimethyl sulfoxide-dicyclohexylcarbodiimide complex, sodium perchlorate.

[0021] In some preferred embodiments of the present invention, the hydrogen abstraction reagent includes one or a combination of two or more of sodium methoxide, sodium ethoxide, sodium isopropoxide, potassium tert-butoxide, sodium hydride, potassium hydride, lithium diisopropylamide, n-butyllithium, sec-butyllithium.

[0022] In some preferred embodiments of the present invention, the ether solvent includes one or a combination of two or more of tetrahydrofuran, dioxane, methyl tert-butyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, tetraethylene glycol dimethyl ether.

[0023] In some preferred embodiments of the present invention, the molar ratio of the dihydroxy-terminated perfluoropolyether to the oxidation reagent is 1:1 to 10; preferably, the molar ratio of the acetyl compound to the hydrogen abstraction reagent is 1:0.9 to 3.

[0024] According to another aspect of the present invention, there is provided a chain-functionalized perfluoropolyether prepared by the above preparation method. The structural formula of the chain-functionalized perfluoropolyether is speculated to be -(R f -A) n -R f -, wherein R f is a perfluoropolyether and A contains an acetyl group.

[0025] According to another aspect of the present invention, there is provided a perfluoropolyether-based elastomer crosslinked from the above chain-functionalized perfluoropolyether.

[0026] In some preferred embodiments of the present invention, the chain-functionalized perfluoropolyether prepared by the present invention is subjected to vulcanization crosslinking to obtain the perfluoropolyether-based elastomer. The specific crosslinking method is well known to those skilled in the art and will not be further limited herein.

[0027] Compared with the prior art, the chain-functionalized perfluoropolyether prepared by the present invention can significantly improve the low-temperature performance of perfluoroether rubber. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Shows the infrared spectrum of the dihydroxy-terminated Z-type perfluoropolyether methyl ester in Example 1.

[0029] Figure 2 Shows the infrared spectrum of the bromine-containing perfluoropolyether in Example 1.

[0030] Figure 3 The infrared spectrum of the Z-type perfluoropolyether carboxylic acid in Example 2 is shown.

[0031] Figure 4 The 1H NMR spectrum of the polyester Z-type perfluoropolyether in Example 5 is shown.

[0032] Figure 5 The infrared spectrum of the allyl Z-type perfluoropolyether in the middle and at the end of the chain in Example 5 is shown. Detailed implementation manners

[0033] For a clearer understanding of the technical features, objectives, and beneficial effects of the present invention, the technical solutions of the present invention are described in detail below, but it should not be construed as a limitation on the implementable scope of the present invention.

[0034] The sources of some reagents used in the following examples and comparative examples are as follows:

[0035] Bis-hydroxy-terminated Z-type perfluoropolyether (Fluorolink D10H, abbreviated as D10H), bis-Y-type perfluoropolyether methyl ester: industrial grade, purchased from Solvay, Italy. Bis-K-type perfluoropolyether methyl ester: industrial grade, purchased from Tianjin Changlu New Chemical Materials Co., Ltd. Potassium permanganate, nitric acid, hydrogen peroxide, methanol: reagent grade, Sinopharm Chemical Reagent Co., Ltd. Sodium methoxide, sodium isopropoxide, ethyl fluoroacetate, bromotrifluoroacetone, tetrahydrofuran, methyl tert-butyl ether: reagent grade, Shanghai Titan Technology Co., Ltd.

[0036] Analysis and evaluation methods:

[0037] The polymer was subjected to NMR scanning using a Bruker MX-400 nuclear magnetic resonance spectrometer produced by Bruker, Germany: 10 - 15 mg of the product was taken and dissolved in a nuclear magnetic tube, and deuterated chloroform was used as the solvent, and the scanning frequency was 400 MHz.

[0038] Fourier transform infrared spectrometer (FTIR): Model: Bruker Tensor 27 was used to measure the infrared spectrum of the product. The attenuated total reflection method (ATR) was used for measurement, and the test conditions were: resolution 3 cm -1 , scanning range 4000 - 500 cm -1 . Sample preparation: film coating method and tablet pressing method; reference substance: potassium bromide.

[0039] Example 1

[0040] This example provides a preparation method of a functionalized perfluoropolyether in the middle of the chain, specifically including:

[0041] S1. Place 100 g of D10H (average molecular weight is about 1500, and when it comes to molecular weight hereinafter, unless otherwise specified, it is the average molecular weight), 50.4 g of nitric acid aqueous solution (mass fraction of nitric acid is 50%) into a three-necked flask, heat up to 45 °C, stir for 30 min, then add 105 g of potassium permanganate in batches (5 times) in total, stir for 1 h, then heat up to 95 °C, stir for 24 h, then cool to 40 °C, add 100 g of methanol in sequence and stir rapidly for 30 min, then filter by suction, wash the filter cake with fluorocarbon solvent for 3 times, and finally separate and concentrate the filtrate to obtain 95 g of bis-terminal Z-type perfluoropolyether methyl ester (the first intermediate product), and its infrared spectrum is as Figure 1 shown, the hydroxyl peak at 3305 cm -1 disappears, and the carbon-oxygen double bond peak on the ester group appears at 1796 cm -1 .

[0042] S2. Add 3.18 g of bromotrifluoroacetone, 20 mL of methyl tert-butyl ether, 1.9 g of sodium methoxide and 3 mL of methanol into a three-necked flask, heat up to 60 °C, stir for 2 h to obtain an intermediate product containing carbanion.

[0043] S3. Add 50 g of bis-terminal Z-type perfluoropolyether methyl ester to the intermediate product containing carbanion, continue to stir at 60 °C for 12 h, then cool to room temperature, add 10 mL of 1 mol / L hydrochloric acid and 50 mL of fluorocarbon solvent and stir for 10 min, then separate and concentrate to obtain 45 g of light yellow bromine-containing perfluoropolyether, and its infrared spectrum is as Figure 2 shown, the carbon-oxygen double bond peak on the ketone group appears at 1704 cm -1 , and the bound water peak on the ketone group appears at 3469 cm -1 . Its structural formula is speculated as follows:

[0044] .

[0045] Example 2

[0046] This example provides a preparation method of chain-functionalized perfluoropolyether, which specifically includes:

[0047] S1. Place 100 g of D10H (molecular weight is about 1500) and 100 g of distilled water into a three-necked flask, heat up to 45 °C, stir for 30 min, then add 105 g (in total) of potassium permanganate in batches (5 times), stir for 1 h, then heat up to 95 °C, stir for 7 h, cool to 40 °C, slowly add hydrogen peroxide (mass fraction is 10%) aqueous solution until the solid disappears, then continue to stir at 60 °C for 6 h, cool to room temperature, separate the liquid, and concentrate the lower layer liquid to obtain 90 g of Z-type perfluoropolyether carboxylic acid, and its infrared spectrum is as Figure 3As shown, 1782 cm -1 The carbon-oxygen double bond peak on the carboxylic acid appears, and the pH value is 1-2; in 90 g of Z-type perfluoropolyether carboxylic acid, 20 g of methanol is added, and the mixture is stirred at 50 °C for 5 h, cooled, separated by liquid and concentrated to obtain 88 g of colorless and transparent Z-type perfluoropolyether methyl ester with double ends (the first intermediate).

[0048] S2, Add 3.18 g of bromotrifluoroacetone, 20 mL of tetrahydrofuran, 2.9 g of sodium isopropoxide and 3 mL of methanol to a three-necked flask, heat up to 60 °C, and stir for 2 h to obtain an intermediate product containing carbanion.

[0049] S3, Add 50 g of Z-type perfluoropolyether methyl ester with double ends to the intermediate product containing carbanion, continue to stir for 12 h, cool to room temperature, add 10 mL of 1 mol / L hydrochloric acid and 50 mL of fluorocarbon solvent, stir for 10 min, then separate by liquid and concentrate to obtain 48 g of light yellow bromine-containing perfluoropolyether, and its structural formula is speculated as follows:[[]]

[0050] .

[0051] Example 3

[0052] The difference from Example 2 is that the Z-type perfluoropolyether methyl ester with double ends is replaced by the K-type perfluoropolyether methyl ester with double ends, and the rest remains unchanged, to obtain the bromine-containing K-type perfluoropolyether methyl ester in the chain, and its structural formula is speculated as follows, and the yield is about 85%:[[]]

[0053] .

[0054] Example 4

[0055] The difference from Example 2 is that the Z-type perfluoropolyether methyl ester is replaced by the Y-type perfluoropolyether methyl ester with double ends, and the rest remains unchanged, to obtain the bromine-containing Y-type perfluoropolyether methyl ester in the chain, and its structural formula is speculated as follows, and the yield is about 80%:[[]]

[0056] .

[0057] Example 5

[0058] The difference from Example 2 is that bromotrifluoroacetone is replaced by ethyl fluoroacetate, and the rest remains unchanged, to obtain multi-ester Z-type perfluoropolyether, and the yield is about 95%, and its structural formula is speculated as follows, and its 1H NMR spectrum is as Figure 4 shown, where 2.75-3.34 ppm is the H peak on the methyl ester, 3.63-3.99 ppm is the H peak on CH2 in the ethyl group in the chain, and 0.67-0.91 ppm is the H peak on CH3 in the ethyl group in the chain:[[]]

[0059] ;

[0060] Then, 20 g of multi-ester Z-type perfluoropolyether, 1.7 g of allylamine, and 10 mL of methyl tert-butyl ether were placed in a three-necked flask and reacted at 50 °C for 24 h. Then, the by-products and excess allylamine were removed under reduced pressure at 60 °C to obtain chain-end allyl Z-type perfluoropolyether. The yield was about 90%. Its structural formula was speculated as follows, and its infrared spectrum was as shown in Figure 5 shown:

[0061] .

[0062] Example 6

[0063] The difference from Example 5 was that the double-end Z-type perfluoropolyether methyl ester was replaced with a double-end K-type perfluoropolyether methyl ester, and the rest remained unchanged, obtaining chain-end allyl K-type perfluoropolyether methyl ester with a yield of about 95%.

[0064] Example 7

[0065] The difference from Example 5 was that the double-end Z-type perfluoropolyether methyl ester was replaced with a double-end Y-type perfluoropolyether methyl ester, and the rest remained unchanged, obtaining chain-end allyl Y-type perfluoropolyether methyl ester with a yield of about 90%.

[0066] Preparation of perfluoropolyether-based elastomer:

[0067] The chain-functionalized perfluoropolyethers in Examples 2-7 were respectively mixed with perfluoroether rubber (grade 31TZ, 3M, USA) at a mass ratio of 20:80. Then, peroxide DCP (the addition amount accounted for 2% of the mass of perfluoroether rubber) and cross-linking agent TAIC (the addition amount accounted for 1% of the mass of perfluoroether rubber) were added and mixed multiple times. After curing at 200 °C for 4 h, perfluoropolyether-based elastomers were prepared and named samples A-F in sequence. Their glass transition temperatures are shown in Table 1.

[0068] Table 1

[0069]

[0070] As can be seen from Table 1, the glass transition temperatures of samples A-F are all relatively low, significantly lower than those of perfluoroether rubber, indicating that the chain-functionalized perfluoropolyethers prepared in this invention can significantly improve the low-temperature performance of perfluoroether rubber.

Claims

1. A method for preparing a chain-functionalized perfluoropolyether, characterized in that: include: S1, mixing a double-terminated hydroxyl perfluoropolyether, an oxidizing agent, and a solvent, reacting to obtain an oxidation product, and mixing the oxidation product with an alcohol to obtain a first intermediate product; in S1, the reaction temperature is 60-120° C., and the reaction time is 1-72 hours; the oxidizing agent includes one or a combination of two or more of potassium permanganate, potassium dichromate, sodium dichromate, chromium trioxide, potassium peroxymonosulfonate, nitric acid, oxygen, hydrogen peroxide, dimethyl sulfoxide-dicyclohexylcarbodiimide complex, and sodium perchlorate; the molar ratio of the double-terminated hydroxyl perfluoropolyether to the oxidizing agent is 1:1-10; S2, mixing an acetyl compound, a hydrogenation reagent, and an ether solvent to react to obtain a second intermediate product containing a carbon anion; in S2, the reaction temperature is 0-60°C, and the reaction time is 0.2-5h; the molar ratio of the acetyl compound to the hydrogenation reagent is 1:0.9-3; the acetyl compound includes one or a combination of two or more of ethyl haloacetate, methyl haloacetate, halogenated acetone, ethyl halomalonate, and methyl halomalonate; S3, mixing the first intermediate product and the second intermediate product, reacting them, and separating the products to obtain the in-chain functionalized perfluoropolyether.

2. The preparation method according to claim 1, characterized in that: In S3, the reaction temperature is 25-120° C. and the reaction time is 0.5-36 h.

3. The preparation method according to claim 1, characterized in that: The average molecular weight of the double-terminated hydroxyl perfluoropolyether is 1000-10000.

4. The preparation method according to claim 1, characterized in that: The alcohol includes methanol and / or ethanol.

5. The preparation method according to claim 1, characterized in that: The dihydroxyl-terminated perfluoropolyether includes one or a combination of two or more of dihydroxyl-terminated K-type perfluoropolyether, dihydroxyl-terminated Y-type perfluoropolyether and dihydroxyl-terminated Z-type perfluoropolyether.

6. The preparation method according to claim 1, characterized in that: The hydrogen extraction reagent includes one or a combination of two or more of sodium methoxide, sodium ethoxide, sodium isopropoxide, potassium tert-butoxide, sodium hydride, potassium hydride, lithium diisopropylamide, n-butyl lithium, and sec-butyl lithium.

7. The preparation method according to claim 1, characterized in that: The ether solvent includes one or a combination of two or more of tetrahydrofuran, dioxane, methyl tert-butyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, and tetraethylene glycol dimethyl ether.

8. A mid-chain functionalized perfluoropolyether prepared by the preparation method according to any one of claims 1 to 7.

9. A perfluoropolyether-based elastomer, characterized in that: The polyfluorocarbon is obtained by cross-linking the chain-functionalized perfluoropolyether as claimed in claim 8.

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