Perfluoropolyether functionalized in fluorinated chain, preparation method therefor, and use thereof, and modified perfluoroether rubber

Abstract

Disclosed are a perfluoropolyether functionalized in a fluorinated chain, a preparation method therefor and a use thereof, and a modified perfluoroelastomer. The perfluoropolyether has a structure as shown in formula (I): formula (I); in formula (I), A and B are each independently selected from a substituted or unsubstituted ester group; Rf is a perfluoropolyether segment; X1 and X2 are each independently hydroxyl, a fluorine element, or fluorinated alkyl; Y is a halogen or a hydrogen atom; and C is a carbon atom. The perfluoropolyether functionalized in the fluorinated chain has excellent thermal stability, and the functionalized perfluoropolyether can be self-crosslinked, or compounded and crosslinked with a fluoroelastomer, a perfluoroelastomer, a fluorosilicone rubber, or a non-fluoroelastomer to finally obtain a product having low-temperature performance and thermal stability.

Description

Functionalized perfluoropolyethers in fluorinated chains, their preparation methods and applications, and modified perfluoroether rubbers

[0001] Cross-reference to related applications

[0002] This application claims the benefit of Chinese Patent Application No. 202411591139.8, filed on November 8, 2024, the contents of which are incorporated herein by reference. Technical Field

[0003] This invention relates to the field of polymers, specifically to a functionalized perfluoropolyether in a fluorinated chain, its preparation method and application, and modified perfluoroether rubber. Background Technology

[0004] In recent years, with the rapid development of smart devices, smart wearables, AI-powered operations, AI-enabled homes, and smart express sorting, the demand for high-end AI chips has been increasing. Chip manufacturing (etching, printing, editing) equipment requires sealing materials with high solvent and corrosion resistance, primarily perfluoroelastomer (FFKM). However, FFKM's glass transition temperature (Tg) is around -30°C, resulting in poor resilience under low-temperature operating conditions and its high cost, which has limited its application in many fields. Therefore, it is necessary to incorporate polymers with a Tg value below -30°C and good compatibility with FFKM to improve its low-temperature performance.

[0005] Due to the unique properties of FFKM, it was initially used in the military, aerospace, and petroleum industries. Most research on it has been classified, with very little publicly available information, so a clear solution for improving the low-temperature performance of FFKM remains elusive. Recently, perfluoropolyether (PFPE)-based elastomers, which possess excellent low-temperature performance, have become a research hotspot. Clearly, utilizing PFPE with a low Tg value (-110℃ to -50℃) can effectively improve the low-temperature performance of FFKM. Furthermore, PFPE and FFKM have high compatibility and can be mixed and processed in any proportion.

[0006] EP 0195946A2 discloses a method for preparing bromine-terminated PFPE and discovers that this substance can be co-cured with fluororubber under the action of peroxides. The results show that the modified fluororubber becomes easier to process, the mold release properties and thermal stability of the products are improved, and its mechanical properties, compression set, and solvent resistance remain almost unchanged. This means that as long as the PFPE molecular chain contains crosslinkable groups, it can be co-cured and crosslinked with FFKM.

[0007] However, the molecular weight of PFPE has a significant impact on the performance of FFKM. When the molecular weight is below 2000 Da, it tends to migrate to the surface in FFKM compound, which also leads to a decrease in the thermal decomposition temperature of modified FFKM. Summary of the Invention

[0008] The applicant of this invention previously studied a new perfluoropolyether molecular chain containing ketone groups. Further research revealed that the active groups on the perfluoropolyether molecular chain, such as ketone groups, are prone to chain breakage under continuous high temperature, which may cause the product to fail during use and thus cause an accident.

[0009] Based on this, the applicant of this invention has discovered a new functionalized perfluoropolyether with crosslinking functional groups. Specifically, the first aspect of this invention provides a functionalized perfluoropolyether in the fluorination chain, wherein the perfluoropolyether has the structure shown in formula (I):

[0010] In formula (I): A and B are each independently selected from substituted or unsubstituted ester groups; Rf is a perfluoropolyether segment; X1 and X2 are each independently a hydroxyl group, a fluorine element, or a fluorinated alkyl group; Y is a halogen or a hydrogen atom; and C is a carbon atom.

[0011] A second aspect of this invention provides a method for preparing functionalized perfluorinated polyethers in a fluorinated chain, the method comprising:

[0012] The ketone-based perfluoropolyether shown in formula (I1) undergoes a first fluorination reaction with fluorinating agent A, followed by a first purification, optionally a second fluorination reaction in the presence of fluorinating agent B, and optionally a second purification.

[0013] In formula (I1), the definitions of A, B, Rf, and Y are the same as those in the perfluoropolyether described in the first aspect of this invention; C is a carbon atom and O is an oxygen atom.

[0014] A third aspect of the present invention provides a fluorinated perfluoropolyether functionalized in a fluorinated chain, wherein the fluorinated perfluoropolyether functionalized in a fluorinated chain is prepared by the preparation method described in the second aspect of the present invention.

[0015] The fourth aspect of the invention provides the application of the functionalized perfluoropolyether in the fluorinated chain described in the first or third aspect of the invention in modified rubber.

[0016] The fifth aspect of the present invention provides a modified perfluoroether rubber, wherein the modified perfluoroether rubber is obtained by vulcanizing a perfluoroether rubber with a functionalized perfluoropolyether in the fluorinated chain as described in the first aspect or the third aspect of the present invention.

[0017] Through the above technical solutions

[0018] 1. The functionalized perfluoropolyether in the fluorinated chain of the present invention has excellent thermal stability;

[0019] 2. Existing modified perfluoroether rubbers are difficult to balance their low-temperature performance and thermal stability. That is, modifying perfluoroether rubber with modifiers increases its low-temperature performance but leads to a decrease in thermal decomposition temperature. However, the functionalized perfluoropolyether in the specific fluorinated chain of the present invention can self-crosslink or be compounded and crosslinked with fluororubber, perfluoroether rubber, fluorosilicone rubber and / or non-fluororubber to finally obtain a product with a balance between low-temperature performance and thermal stability. Attached Figure Description

[0020] Figure 1 is the infrared spectrum of the Z-type perfluoropolyether carboxylic acid used in Preparation Example 1;

[0021] Figure 2 is the infrared spectrum of Keto-PFPE-1 in Preparation Example 1;

[0022] Figure 3 is the 1H NMR spectrum of Keto-PFPE-1 in Preparation Example 1;

[0023] Figure 4 is the infrared spectrum of the functionalized perfluoropolyether (F1) in the fluorinated chain in Example 1;

[0024] Figure 5 is the infrared spectrum of the functionalized perfluoropolyether (F2) in the fluorinated chain in Example 4;

[0025] Figure 6 is the NMR spectrum of the functionalized perfluoropolyether (F3) in the fluorinated chain in Example 5. Detailed Implementation

[0026] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0027] In this invention, "room temperature" refers to "15-30℃".

[0028] Solvent A in this invention is used merely to distinguish it from solvents used in other steps, and is not a specific limitation on the solvent used.

[0029] In this invention, the first fluorination reaction and the second fluorination reaction are merely to distinguish the different steps of the fluorination reaction, and are not used to limit the fluorination reaction. Similarly, the first purification and the second purification are merely to distinguish the different steps of the purification.

[0030] A first aspect of the present invention provides a functionalized perfluoropolyether in a fluorinated chain, the perfluoropolyether having the structure shown in formula (I):

[0031] In formula (I): A and B are each independently selected from substituted or unsubstituted ester groups; Rf is a perfluoropolyether segment; X1 and X2 are each independently a hydroxyl group, a fluorine element, or a fluorinated alkyl group; Y is a halogen or a hydrogen atom; and C is a carbon atom.

[0032] The fluorinated chain functionalized perfluoropolyether in this invention has excellent thermal stability. Using the fluorinated chain functionalized perfluoropolyether in this invention to modify rubber, especially perfluoroether rubber, can not only increase the low-temperature resistance of the modified rubber, but also achieve a balance between the low-temperature performance and thermal stability of the modified rubber without significantly reducing its heat resistance.

[0033] According to the present invention, the range of ester groups is relatively wide as long as the purpose of the present invention can be achieved. In one embodiment, in formula (I): A and B are each independently selected from substituted or unsubstituted C1-C. 12 Ester groups, wherein C1 ester group refers to esters, C2 ester group refers to ethyl esters, and so on, and the C1-C group can be listed in this invention. 12 The ester group includes methyl ester, ethyl ester, propyl ester, butyl ester, pentyl ester, hexyl ester, heptyl ester, octyl ester, etc. In preferred formula (I): A is selected from substituted or unsubstituted C1-C5 ester groups; in preferred formula (I): B is selected from substituted or unsubstituted C1-C3 ester groups.

[0034] In this invention, substituted or unsubstituted ester groups refer to at least one H on the ester group being replaced by a substituent or not being replaced by a substituent. As long as the purpose of this invention can be achieved, there is no special limitation on the type of substituent when a substituent is present on the ester group. In one embodiment, the substituents present in A and B are each independently selected from at least one of halogens, silyl groups, and boron alkyl groups, preferably halogens. Examples of halogens include F, Cl, Br, and I.

[0035] According to a preferred embodiment of the present invention, in formula (I): at least one group in X1 and X2 is a fluorine element or a fluorinated alkyl group.

[0036] According to a preferred embodiment of the present invention, in formula (I): X1 and X2 are each independently a hydroxyl group, a fluorine element, or a trifluoromethyl group.

[0037] According to the present invention, the selection of the perfluoropolyether segment is not particularly limited as long as the objective of the present invention can be achieved. In one embodiment, the perfluoropolyether segment is selected from at least one of K-type perfluoropolyether segments, D-type perfluoropolyether segments, Y-type perfluoropolyether segments, and Z-type perfluoropolyether segments. The Z-type perfluoropolyether chain is used as an example to illustrate the advantages of the present invention, but the present invention is not limited thereto.

[0038] According to the present invention, the following embodiments of perfluoropolyethers can be cited:

[0039] In one embodiment, the perfluoropolyether has structure 1: In formula (I), Rf is a Z-type perfluoropolyether structural unit, A is a methyl ester group, B is an ethyl ester group, X1 is a fluorine element, X2 is a fluorine element, and Y is a fluorine element.

[0040] In one embodiment, the perfluoropolyether has structure 2: In formula (I), Rf is a Z-type perfluoropolyether structural unit, A is a methyl ester group, B is an ethyl ester group, X1 is a hydroxyl group, X2 is a trifluoromethyl group, and Y is a fluorine element.

[0041] In one embodiment, the perfluoropolyether has structure 3: In formula (I), Rf is a Z-type perfluoropolyether structural unit, A is a methyl ester group, B is an ethyl ester group, X1 is fluorine element, X2 is trifluoromethyl, and Y is fluorine element.

[0042] According to a preferred embodiment of the present invention, the average molecular weight of the perfluoropolyether is 1000-10000, for example, 1000, 1500, 3200, 4000, 5000, 6000, 7000, 8000, 9000 or 10000.

[0043] The preparation method of the functionalized perfluoropolyether in the fluorinated chain in this invention is not particularly limited, but it is preferred to be prepared according to the preparation method described in the second aspect of this invention.

[0044] A second aspect of this invention provides a method for preparing functionalized perfluorinated polyethers in a fluorinated chain, the method comprising:

[0045] The ketone-based perfluoropolyether shown in formula (I1) undergoes a first fluorination reaction with fluorinating agent A, followed by a first purification, optionally a second fluorination reaction in the presence of fluorinating agent B, and optionally a second purification.

[0046] In formula (I1), the definitions of A, B, Rf, and Y are the same as those in the perfluoropolyether described in the first aspect of this invention; C is a carbon atom and O is an oxygen atom.

[0047] The applicant of this invention previously studied a new perfluoropolyether molecular chain containing ketone groups. Further research revealed that the active groups on the perfluoropolyether molecular chain, such as ketone groups, are prone to chain breakage under continuous high temperature, which may lead to product failure during use and thus cause accidents. The fluorinated functionalized perfluoropolyether obtained by the preparation method described above in this invention has excellent thermal stability, and when used to modify rubber, it can improve the low-temperature resistance of rubber without significantly reducing the heat resistance of rubber.

[0048] According to a preferred embodiment of the present invention, the average molecular weight of the ketone-based perfluoropolyether is 1000-10000, for example, 1000, 1500, 3200, 4000, 5000, 6000, 7000, 8000, 9000 or 10000.

[0049] According to a preferred embodiment of the present invention, the preparation method of the ketone-based perfluoropolyether includes: in the presence of solvent A, the halogenated ester of formula (I12) undergoes a first contact reaction with a hydrogen-removing reagent, and then undergoes a second contact reaction with the bi-terminated ester-based perfluoropolyether of formula (I11);

[0050] A-Rf-A formula (I11),

[0051] In formulas (I11) and (I12), the definitions of A, Rf, and B are the same as those in the perfluoropolyether described in the first aspect of this invention.

[0052] According to the present invention, as long as the purpose of the present invention can be achieved, the amount of the di-terminated ester-based perfluoropolyether and the halide ester can be selected within a wide range. In one embodiment, the molar ratio of the di-terminated ester-based perfluoropolyether to the halide ester is 1.2-3:1.

[0053] According to the present invention, the amount of the dehydrogenating agent can be selected within a wide range as long as the purpose of the present invention can be achieved. In one embodiment, the molar ratio of the halide ester to the dehydrogenating agent is 1:0.9-3.

[0054] According to the present invention, the size of the bi-terminated ester-based perfluoropolyether can be selected within a wide range as long as the purpose of the present invention can be achieved. In one embodiment, the average molecular weight of the bi-terminated ester-based perfluoropolyether is 1000-10000.

[0055] According to a preferred embodiment of the present invention, the dehydrogenating agent is selected from at least one of sodium methoxide, sodium ethoxide, sodium isopropoxide, potassium tert-butoxide, sodium hydride, potassium hydride, lithium diisopropylamino, lithium n-butyl, and lithium sec-butyl.

[0056] According to the present invention, some dehydrogenating agents are solids. In order to enable the dehydrogenating agents to better facilitate the formation of carbanion intermediates from halogenated esters, in one embodiment, the dehydrogenating agent is dissolved in an alcohol solvent and reacts with the halogenated ester in the first contact reaction. The type of solvent is not particularly limited, but preferably the alcohol solvent is selected from C1-C3 alcohols, such as methanol, ethanol, or propanol. The amount of alcohol solvent is not particularly limited, for example, 1-5 g of dehydrogenating agent is dissolved in each milliliter of alcohol solvent.

[0057] According to the present invention, the type of solvent A is not particularly limited as long as the purpose of the present invention can be achieved. In a preferred embodiment, solvent A is selected from ether solvents, preferably including at least one 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. The amount of solvent A used is not particularly limited as long as the purpose of the present invention can be achieved. For example, each gram of halide ester is dissolved in 8-20 mL of solvent A.

[0058] According to a preferred embodiment of the present invention, the conditions for the first contact reaction include: a reaction temperature of 0-60°C, for example, 0°C, 5°C, 10°C, 20°C, 40°C, or 60°C.

[0059] According to a preferred embodiment of the present invention, the conditions for the first contact reaction include a time of 0.2-5 hours, for example, 0.2 hours, 1 hour, 2 hours, 3 hours, 4 hours or 5 hours.

[0060] According to a preferred embodiment of the present invention, the conditions for the second contact reaction include: a reaction temperature of 25-120°C, for example, 25°C, 30°C, 45°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C or 120°C.

[0061] According to the present invention, the product obtained after the second contact reaction may contain some solvents and byproducts, and the target product can be obtained by any separation and purification method in the art. In one embodiment, the preparation method of the ketone-based perfluoropolyether further includes: separation and purification in the presence of fluorocarbon solvent and acid after the second contact reaction.

[0062] According to the present invention, a fluorocarbon solvent is a fluorinated compound whose molecule does not contain chlorine or hydrogen atoms, and is composed of fluorine, carbon, or oxygen and nitrogen atoms. The fluorocarbon solvent in the present invention is a conventional fluorocarbon solvent in the art, and the present invention will not elaborate on it further; there are no special restrictions on the specific selection of the fluorocarbon solvent.

[0063] According to the present invention, there is no particular limitation on the type of acid, which is generally an aqueous solvent of an inorganic acid, such as hydrochloric acid with a concentration of 0.5-2 mol / L; wherein, the amount of acid can be selected as needed.

[0064] The source of the bi-terminated ester-based perfluoropolyether represented by formula (I11) in this invention is not particularly limited, as long as it can achieve the purpose of this invention. For example, it can be prepared by reacting the corresponding bi-terminated carboxyl-based perfluoropolyether with the corresponding alcohol. The bi-terminated carboxyl-based perfluoropolyether can be prepared by oxidizing the corresponding bi-terminated hydroxyl-based perfluoropolyether. In one embodiment, the preparation method of the bi-terminated ester-based perfluoropolyether includes: in the presence of an oxidant and a solvent, the bi-terminated hydroxyl-based perfluoropolyether undergoes an oxidation reaction, and the bi-terminated carboxyl-based perfluoropolyether obtained by the oxidation reaction undergoes an esterification reaction with a substituted or unsubstituted alkyl alcohol.

[0065] In this invention, the oxidant used in preparing the hydroxyl-terminated perfluoropolyether can be a conventional oxidant in the art, such as potassium permanganate, potassium dichromate, sodium dichromate, chromium trioxide, potassium peroxymonosulfonate, nitric acid, oxygen, hydrogen peroxide, dimethyl sulfoxide-dicyclohexylcarbodiimide complex, sodium perchlorate, etc. The oxidant can be added in batches, with different or the same type added, for example, potassium permanganate can be added first, followed by hydrogen peroxide. There is no particular limitation on the amount of oxidant used, as long as the hydroxyl groups at both ends of the hydroxyl-terminated perfluoropolyether are completely oxidized to carboxyl groups. For example, the amount of oxidant used is 50-120 wt% of the mass of the hydroxyl-terminated perfluoropolyether.

[0066] In this invention, the solvent used in preparing the hydroxyl-terminated perfluoropolyether can be a conventional solvent in the art, such as water; wherein, the amount of solvent used is only required to achieve the purpose of this invention, for example, the amount of solvent used is 50-120 wt% of the mass of the hydroxyl-terminated perfluoropolyether.

[0067] According to the present invention, those skilled in the art can select the corresponding substituted or unsubstituted alkyl alcohol according to the type of A in the final formula (I11), and the present invention will not elaborate on this further; wherein, the type of substituted or unsubstituted alkyl alcohol is sufficient to enable the carboxyl groups at both ends of the bi-terminal carboxyl perfluoropolyether to be completely esterified.

[0068] In this invention, there are no special restrictions on the conditions of the oxidation reaction when preparing double-hydroxyl-terminated perfluoropolyether, as long as the purpose of this invention can be achieved. Different oxidants have different activities at different temperatures, and the appropriate temperature can be selected according to the type of catalyst. Generally, the conditions for oxidation reaction include: temperature of 60-120℃ and time of 1-72h.

[0069] In the preparation of double-hydroxyl-terminated perfluoropolyether in this invention, after the oxidation reaction, the lower layer can be separated and concentrated to obtain double-carboxyl-terminated perfluoropolyether.

[0070] In this invention, the esterification reaction conditions for preparing double-hydroxyl-terminated perfluoropolyethers include: a temperature of 30-100℃ and a time of 1-24h.

[0071] In the preparation of bihydroxyl-terminated perfluoropolyether in this invention, after the esterification reaction, the lower liquid can be separated and concentrated to obtain the two ends of the bihydroxyl-terminated perfluoropolyether; wherein, separation and concentration are conventional operation methods in the art.

[0072] According to the present invention, the fluorinating agents A and B can be selected from a variety of types as long as the purpose can be achieved. In a preferred embodiment, the fluorinating agent A and the fluorinating agent B each independently include at least one of sulfur tetrafluoride, bis(2-methoxyethyl)aminosulfur trifluoride, diethylaminosulfur trifluoride, 4-tert-butyl-2,6-dimethylphenylsulfur trifluoride (Fluolead fluorinating agent), nonafluorobutylsulfonyl fluoride, trifluoromethyltrimethylsilane, difluoromethyltrimethylsilane, and trifluoroacetic anhydride.

[0073] According to the present invention, in order to promote the first fluorination reaction and the second fluorination reaction, the first fluorination reaction and the second fluorination reaction can each be carried out in the presence of a catalyst, or in the presence of a solvent, or in the presence of both a catalyst and a solvent. In a preferred embodiment, the first fluorination reaction and the second fluorination reaction are each carried out independently in a catalyst and / or a solvent.

[0074] According to the present invention, the type of catalyst is not particularly limited as long as it can promote the occurrence of the corresponding fluorination reaction. In one embodiment, the catalyst includes at least one selected from hydrogen fluoride, potassium fluoride, cesium fluoride, triethylamine hydrogen fluoride, sodium hydrogen fluoride, and ammonium hydrogen fluoride. The type of catalyst is only required to promote the occurrence of the corresponding fluorination reaction. Preferably, the molar ratio of the catalyst to the ketone-based perfluoropolyether is 0.5-5:1, for example, 0.5:1, 1:1, 1.5:1, 2.5:1, 3.5:1, 4.5:1, or 5:1.

[0075] According to the present invention, the type of solvent is not particularly limited as long as the purpose of the present invention can be achieved. In one embodiment, the solvent is selected from fluorocarbon solvents and / or non-fluoroether solvents; preferably, the fluorocarbon solvent includes at least one of nonafluorobutyl ethyl ether, nonafluorobutyl methyl ether, trifluorotoluene, m-difluorotrifluorotoluene, perfluorocyclic ether, and perfluorohexane; preferably, the non-fluoroether solvent includes at least one of tetrahydrofuran, dioxane, methyl tert-butyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, and tetraethylene glycol dimethyl ether; wherein, the amount of solvent used is not particularly limited, for example, 1-5g of ketone-based perfluoropolyether is used with 1mL of solvent.

[0076] According to a preferred embodiment of the present invention, the molar ratio of the ketone-based perfluoropolyether to fluorinating agent A and fluorinating agent B is 1:1.5-10, for example, 1:1.5, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9 or 1:10.

[0077] The present invention optionally involves a second fluorination reaction in the presence of fluorinating agent B, and optionally a second purification refers to the second fluorination reaction performed or not performed after the first fluorination reaction, depending on the needs of X1 and X2 in formula (I), and a second purification after the second fluorination reaction.

[0078] According to the present invention, the reaction conditions for the first fluorination reaction and the second fluorination reaction can be selected according to the type of the corresponding fluorination reagent, the presence or absence of a catalyst and solvent in the reaction system. In a preferred embodiment, the conditions for the first fluorination reaction and the second fluorination reaction each independently include: a reaction temperature of 0-100°C, for example, 0°C, 10°C, 20°C, 30°C, 40°C, 50°C, 70°C, 80°C or 100°C.

[0079] According to the present invention, the time for the first fluorination reaction and the second fluorination reaction can be selected according to the temperature. In a preferred embodiment, the conditions for the first fluorination reaction and the second fluorination reaction each independently include: a reaction time of 1-72h, for example, 1h, 3h, 5h, 10h, 12h, 15h, 20h, 24h, 30h, 34h, 40h, 50h, 60h, 70h or 72h.

[0080] According to the present invention, after the first fluorination reaction and the second fluorination reaction, there may be unreacted raw materials, other impurities, and non-target product components such as solvents. Appropriate purification methods are required to purify the product to obtain the target product. In one embodiment, the first purification and the second purification methods include: extraction in the presence of an extractant and an alkali, and removal of the extractant from the liquid phase extract.

[0081] According to a preferred embodiment of the present invention, the alkali includes at least one of potassium hydroxide, sodium hydroxide, calcium hydroxide, potassium carbonate, sodium carbonate, sodium bicarbonate, sodium methoxide, sodium ethoxide, potassium tert-butoxide, and ammonia water.

[0082] Some of the bases (i.e., alkaline compounds) in this invention are solids. The alkaline compounds can dissolve in water to form an alkaline aqueous solution which is then added to the system. Generally, the concentration of the alkaline aqueous solution is 10-30 wt%. Preferably, the amount of alkaline compound used makes the pH value of the system 4-7.

[0083] According to a preferred embodiment of the present invention, the extractant is selected from organic alcohol compounds, preferably including C1-C4 alcohols and / or fluorinated C1-C4 alcohols. Examples of C1-C4 alcohols include methanol, ethanol, isopropanol, tert-butanol, ethylene glycol, etc.; examples of fluorinated C1-C4 alcohols include hexafluoroisopropanol and perfluorotert-butanol.

[0084] In this invention, after extraction, the target product dissolves in the extractant to form an extract. Separation yields the extract, which may contain some salts, which can be removed by filtration to obtain a liquid extract. The extractant is then removed from the liquid extract to obtain the target product. The method for removing the extractant can be any method in the art, such as conventional rotary evaporation. If the impurity content is high, conventional column chromatography can be used for separation and purification after extractant removal.

[0085] A third aspect of the present invention provides a fluorinated perfluoropolyether functionalized in a fluorinated chain, wherein the fluorinated perfluoropolyether functionalized in a fluorinated chain is prepared by the preparation method described in the second aspect of the present invention.

[0086] The fourth aspect of this invention provides the application of the functionalized perfluoropolyether in the fluorinated chain described in the first or third aspect of this invention in modified rubber.

[0087] Using the functionalized perfluoropolyether in the fluorinated chain of this invention in modified rubber can increase the low-temperature resistance of the rubber without significantly reducing its heat resistance.

[0088] The fifth aspect of the present invention provides a modified perfluoroether rubber, wherein the modified perfluoroether rubber is obtained by vulcanizing a perfluoroether rubber with a functionalized perfluoropolyether in the fluorinated chain as described in the first aspect or the third aspect of the present invention.

[0089] The functionalized perfluoropolyether in the fluorinated chain of this invention can be directly vulcanized with perfluoroether rubber.

[0090] According to the present invention, the vulcanization method is a conventional method in the art, for example, the vulcanization temperature is 150-230°C and the time is 0.5-5h.

[0091] The present invention will be described in detail below through examples. The raw materials used in the following preparation examples and examples are as follows:

[0092] Double-ended perfluoropolyether methyl ester: Industrial grade, PetroChina (Shanghai) New Materials Research Institute Co., Ltd.;

[0093] Methanol, ethyl fluoroacetate, sodium methoxide, dimethyl ethylene glycol: reagent grade, Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0094] Nonafluorobutyl ethyl ether, m-difluorotoluene, diethylaminosulfur trifluoride, 4-tert-butyl-2,6-dimethylphenylsulfur trifluoride (Fluolead), trifluoromethyltrimethylsilane, triethylamine hydrogen fluoride, potassium fluoride: reagent grade, Anhui Zesheng Technology Co., Ltd.

[0095] Sulfur tetrafluoride, perfluorocyclic ethers, hydrogen fluoride: Industrial grade, Shenzhen Tianke New Materials Co., Ltd.

[0096] Unless otherwise specified, all other raw materials are commercially available products.

[0097] The following preparation examples and examples demonstrate the structural analysis and evaluation methods used:

[0098] The polymer was subjected to NMR scanning using a Bruker MX-400 NMR spectrometer manufactured by Bruker GmbH, Germany: 10-15 mg of the product was dissolved in an NMR tube using deuterated chloroform as the solvent, and the scanning frequency was 400 MHz.

[0099] Fourier Transform Infrared Spectrometer (FTIR): Model: Bruker Tensor 27. The infrared spectrum of the product was measured using attenuated total reflectance (ATR) measurement. Test conditions were: resolution 3 cm⁻¹, scan range 4000-500 cm⁻¹. -1 Sample preparation: coating method and tableting method; reference material: potassium bromide.

[0100] Preparation of functionalized perfluoropolyethers in ketone chains

[0101] Preparation Example 1

[0102] S1. 1000g of dihydroxyl-terminated Z-type perfluoropolyether (brand name: SOLVAY D10H, average molecular weight 1500) and 1000g of distilled water were placed in a three-necked flask. The mixture was heated to 45°C and stirred for 30 min. Then, 1050g of potassium permanganate was added in five batches (total). After stirring for 1 h, the mixture was heated to 95°C and stirred for 7 h. The mixture was then cooled to 40°C, and a 10% (w / w) aqueous solution of hydrogen peroxide was slowly added until the solid disappeared. The mixture was then stirred at 60°C for another 6 h. After cooling to room temperature, the mixture was separated, and the lower layer was concentrated to obtain approximately 900g of Z-type perfluoropolyether carboxylic acid. The infrared spectrum of the Z-type perfluoropolyether carboxylic acid is shown in Figure 1. From Figure 1, the 1782 cm⁻¹... -1 The carbon-oxygen double bond peak appears on the carboxylic acid; 200g of methanol is added to about 900g of Z-type perfluoropolyether carboxylic acid, and the mixture is stirred at 50°C for 5h. After cooling, separation and concentration, 880g of colorless and transparent Z-type perfluoropolyether methyl ester is obtained.

[0103] S2 added 9.4 g of ethyl fluoroacetate, 100 mL of tetrahydrofuran, 17.5 g of sodium isopropoxide, and 5 mL of methanol to a three-necked flask. The mixture was heated to 60 °C and stirred for 2 h. Then, 200 g of the aforementioned Z-type perfluoropolyether methyl ester (average molecular weight 1500) was added, and stirring continued for 12 h. After cooling to room temperature, 10 mL of 1 mol / L hydrochloric acid and 50 mL of fluorocarbon solvent were added and stirred for 10 min. The mixture was then separated and concentrated to obtain 192 g of a pale yellow liquid, which was a ketone-based perfluoropolyether (denoted as Keto-PFPE-1). The infrared spectrum of Keto-PFPE-1 is shown in Figure 2; from Figure 2, the 1797 cm⁻¹... -1 and 1746cm -1 The peaks at 3413 cm⁻¹ represent the C=O stretching vibrations of the ester and ketone groups, respectively. -1 The peak at the position represents the hydroxyl peak of water bound to the ketone group; the 1H NMR spectrum of Keto-PFPE-1 is shown in Figure 3, where 2.75–3.34 ppm is the H peak on the methyl ester, 3.63–3.99 ppm is the H peak on the CH2 group of the ethyl group in the chain, and 0.67–0.91 ppm is the H peak on the CH3 group of the ethyl group in the chain. The structural formula of Keto-PFPE-1 is shown below:

[0104] The average molecular weight is approximately 3200, and m and n independently represent the degree of polymerization.

[0105] Examples of preparation of functionalized perfluoropolyethers in fluorinated chains

[0106] Example 1

[0107] 30g of Keto-PFP-1 was added to a fluorination reactor and cooled to -30°C. 5g of sulfur tetrafluoride and 0.5g of hydrogen fluoride were added, and the mixture was heated to 0°C and stirred for 1 hour. Then, the temperature was raised to 120°C and stirred for 8 hours. The mixture was cooled to room temperature, and nitrogen gas was continuously purged for 1 hour. The reactor was then opened, and the crude product was removed. A 20% sodium carbonate aqueous solution was added until no more bubbles were produced, and the pH was measured to be approximately 5.5. A perfluorocyclic ether was added, and the mixture was stirred rapidly for 5 minutes. The mixture was separated, and the lower layer was collected. 18g of functionalized perfluoropolyether (F1) in the fluorinated chain was obtained by rotary evaporation; the liquid was yellow.

[0108] The infrared spectrum of the functionalized perfluoropolyether (F1) in the fluorinated chain is shown in Figure 4. Figure 4 shows that only 1796 cm⁻¹ remains in the functionalized perfluoropolyether (F1) in the fluorinated chain. -1 The ester group; finally, the structural formula of the functionalized perfluoropolyether (F1) in the fluorinated chain is shown below:

[0109] The average molecular weight is 3200.

[0110] Example 2

[0111] 30 g of Keto-PFPE-1 was added to a fluorination reactor, along with 10 mL of m-difluorotoluene, 7 g of diethylaminosulfur trifluoride, and 0.5 g of hydrogen fluoride. The mixture was stirred at 60 °C for 36 h. After cooling to room temperature, a 20% sodium carbonate aqueous solution was added until no more bubbles were produced, and the pH was measured to be approximately 6. A perfluorocyclic ether was added, and the mixture was stirred rapidly for 5 min. The mixture was then separated, and the lower layer was collected. The crude product was obtained by rotary evaporation. The crude product was then dissolved in 200 mL of nonafluorobutyl ether and separated by silica gel column chromatography to finally obtain 8 g of functionalized perfluoropolyether with an average molecular weight of 3200. Its structure was the same as F1, and it was a yellow liquid.

[0112] Example 3

[0113] 30 g of Keto-PFPE-1 was added to a fluorination reactor, along with 10 mL of m-difluorotoluene and 15 g of Fluolead fluorination reagent. The mixture was stirred at 120 °C for 12 h. After cooling to room temperature, a 20% sodium carbonate aqueous solution was added until no more bubbles were generated, and the pH was measured to be approximately 5. A perfluorocyclic ether was added, and the mixture was stirred rapidly for 5 min. The mixture was separated, and the lower layer was collected. The crude product was obtained by rotary evaporation. The crude product was then dissolved in 200 mL of nonafluorobutyl ether and separated by silica gel column chromatography to finally obtain 14 g of functionalized perfluoropolyether with an average molecular weight of 3200. Its structure was identical to that of F1, and it was a yellow liquid.

[0114] Example 4

[0115] 30g of Keto-PFPE was added to a fluorination reactor, along with 10mL of nonafluorobutyl ethyl ether, 20g of trifluoromethyltrimethylsilane, and 2g of potassium fluoride. After stirring at room temperature for 5 hours, 12g of triethylamine hydrogen fluoride was added, and the mixture was heated to 50°C and stirred for another 24 hours. The mixture was then cooled to room temperature, and a 20% sodium carbonate aqueous solution was added until no more bubbles were generated, and the pH was measured to be approximately 6. A perfluorocyclic ether was added, and the mixture was stirred rapidly for 5 minutes. The mixture was then separated, and the lower layer was collected. By rotary evaporation, 23g of functionalized perfluoropolyether (F2) with fluorinated chains was obtained as a pale yellow liquid.

[0116] The infrared spectrum of the functionalized perfluoropolyether (F2) in the fluorinated chain is shown in Figure 5. Figure 5 shows that the functionalized perfluoropolyether (F2) in the fluorinated chain contains 1796 cm⁻¹ -1 ester group and 3423cm -1 The hydroxyl groups. The final structure of the functionalized perfluoropolyether (F2) in the fluorinated chain is shown below:

[0117] The average molecular weight is 3200.

[0118] Example 5

[0119] 20g of the fluorinated chain-functionalized perfluoropolyether (F2) from Example 4 was added to a fluorination reactor, along with 10mL of nonafluorobutyl ethyl ether, 5g of diethylamino trifluoride, and 0.5g of hydrogen fluoride. The mixture was stirred at 50°C for 24 hours. After cooling to room temperature, a 20% sodium carbonate aqueous solution was added until no more bubbles were generated, and the pH was tested to approximately 5. A perfluorocyclic ether was added, and the mixture was stirred rapidly for 5 minutes. The mixture was then separated, and the lower layer was collected. By rotary evaporation, 15g of a ketone-free and hydroxyl-free chain-functionalized perfluoropolyether (F3) was obtained as a pale yellow liquid, with the following structural formula:

[0120] The NMR spectrum of the in-chain functionalized perfluoropolyether (F3) is shown in Figure 6. The calculated average molecular weight of the in-chain functionalized perfluoropolyether (F3) is approximately 3200.

[0121] Comparative Example 1

[0122] Perfluoropolyether dimethyl ester with a molecular weight of 1500.

[0123] Comparative Example 2

[0124] To prepare Keto-PFPE-1 in Example 1.

[0125] Test case

[0126] 1. Stability Test

[0127] Thermogravimetric analysis (TGA) tests were performed on Examples 1, 4, 5, Comparative Example 1, and Preparation Example 1. The test temperature range was from room temperature to 600°C, with a heating rate of 5°C / min, and the tests were conducted under a nitrogen atmosphere. The initial decomposition temperature T was observed. ds .

[0128] 2. Preparation of modified perfluoroether rubber:

[0129] Perfluoroether rubber (grade 31TZ, 3M, USA) was mixed with Examples 1, 4, 5 and Comparative Examples 1 and 2 at a vulcanization mass ratio of 20:80. After vulcanization at 170°C for 30 min and at 200°C for 4 h, vulcanized samples were obtained. Low-temperature resilience test and thermal decomposition test were performed. The test results are shown in Table 2.

[0130] Table 2

[0131] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A functionalized perfluoropolyether in a fluorinated chain, characterized in that, The perfluoropolyether has the structure shown in formula (I): In formula (I): A and B are each independently selected from substituted or unsubstituted ester groups; Rf represents the perfluoropolyether segment; X1 and X2 are each independently a hydroxyl group, a fluorine element, or a fluorinated alkyl group; Y is a halogen or a hydrogen atom; C stands for carbon atom.

2. The perfluoropolyether according to claim 1, characterized in that, In formula (I): A and B are each independently selected from substituted or unsubstituted C1-C. 12 ester group; and / or The substituents present in A and B are each independently selected from at least one of halogen, silyl, and boroalkyl groups.

3. The perfluoropolyether according to claim 2, characterized in that, In formula (I): A is selected from substituted or unsubstituted C1-C5 ester groups; and / or B is selected from substituted or unsubstituted C1-C3 ester groups; and / or The substituents present in A and B are each independently selected from halogens.

4. The perfluoropolyether according to claim 1, characterized in that, In formula (I): At least one group in X1 and X2 is a fluorine element or a fluorinated alkyl group; and / or X1 and X2 are each independently a hydroxyl group, a fluorine element, or a trifluoromethyl group; and / or The perfluoropolyether segment is selected from at least one of the following: K-type perfluoropolyether segment, D-type perfluoropolyether segment, Y-type perfluoropolyether segment, and Z-type perfluoropolyether segment.

5. The perfluoropolyether according to any one of claims 1-4, characterized in that, The perfluoropolyether has one of the following structures: Structure 1: In formula (I), Rf is a Z-type perfluoropolyether structural unit, A is a methyl ester group, B is an ethyl ester group, X1 is a fluorine element, X2 is a fluorine element, and Y is a fluorine element; Structure 2: In formula (I), Rf is a Z-type perfluoropolyether structural unit, A is a methyl ester group, B is an ethyl ester group, X1 is a hydroxyl group, X2 is a trifluoromethyl group, and Y is a fluorine element; Structure 3: In formula (I), Rf is a Z-type perfluoropolyether structural unit, A is a methyl ester group, B is an ethyl ester group, X1 is fluorine element, X2 is trifluoromethyl, and Y is fluorine element.

6. The perfluoropolyether according to any one of claims 1-5, characterized in that, The average molecular weight of the perfluoropolyether is 1000-10000.

7. A method for preparing a functionalized perfluoropolyether in a fluorinated chain, characterized in that, The preparation method includes: The ketone-based perfluoropolyether shown in formula (I1) undergoes a first fluorination reaction with fluorinating agent A, followed by a first purification, optionally a second fluorination reaction in the presence of fluorinating agent B, and optionally a second purification. In formula (I1), the definitions of A, B, Rf, and Y are the same as those in any of the perfluoropolyethers described in claims 1-6; C is a carbon atom and O is an oxygen atom.

8. The preparation method according to claim 7, characterized in that, The ketone-based perfluoropolyether has an average molecular weight of 1000-10000; and / or The preparation method of the ketone-based perfluoropolyether includes: in the presence of solvent A, the halogenated ester of formula (I12) undergoes a first contact reaction with a hydrogen-removing reagent, and then undergoes a second contact reaction with the bi-terminated ester-based perfluoropolyether of formula (I11); In formulas (I11) and (I12), the definitions of A, Rf, and B are the same as those in the perfluoropolyethers described in any one of claims 1-7.

9. The preparation method according to claim 8, characterized in that, The molar ratio of the di-terminated ester-based perfluoropolyether to the halide ester is 1.2-3:1; and / or The molar ratio of the halide ester to the dehydrogenating agent is 1:0.9-3.

10. The preparation method according to claim 8, characterized in that, The average molecular weight of the di-terminated ester-based perfluoropolyether is 1000-10000; and / or The dehydrogen-removing agent is selected from at least one of sodium methoxide, sodium ethoxide, sodium isopropoxide, potassium tert-butoxide, sodium hydride, potassium hydride, lithium diisopropylamino, lithium n-butyl, and lithium sec-butyl. The dehydrogenating agent is dissolved in an alcohol solvent and reacts with a halide ester in the first contact reaction; and / or Solvent A is selected from ether solvents.

11. The preparation method according to claim 10, characterized in that, The alcohol solvent is selected from C1-C3 alcohols; and / or The ether solvents include at least one 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.

12. The preparation method according to claim 8, characterized in that, The conditions for the first contact reaction include: a reaction temperature of 0-60°C and a reaction time of 0.2-5 h; and / or The conditions for the second contact reaction include: a reaction temperature of 25-120°C and a time of 0.5-36 h; and / or The preparation method of the ketone-based perfluoropolyether further includes: separation and purification in the presence of fluorocarbon solvent and acid after the second contact reaction.

13. The preparation method according to any one of claims 7-12, characterized in that, The fluorinating agent A and fluorinating agent B each independently include at least one of sulfur tetrafluoride, bis(2-methoxyethyl)aminosulfur trifluoride, diethylaminosulfur trifluoride, 4-tert-butyl-2,6-dimethylphenylsulfur trifluoride, nonafluorobutylsulfonyl fluoride, trifluoromethyltrimethylsilane, difluoromethyltrimethylsilane, and trifluoroacetic anhydride; and / or The first fluorination reaction and the second fluorination reaction are carried out independently in a catalyst and / or solvent.

14. The preparation method according to claim 13, characterized in that, The catalyst comprises at least one of hydrogen fluoride, potassium fluoride, cesium fluoride, triethylamine hydrogen fluoride, sodium hydrogen fluoride, and ammonium hydrogen fluoride; and / or The solvent is selected from fluorocarbon solvents and / or non-fluoroether solvents; and / or The molar ratio of the catalyst to the ketone-based perfluoropolyether is 0.5-5:

1.

15. The preparation method according to claim 14, characterized in that, The fluorocarbon solvent includes at least one selected from nonafluorobutyl ethyl ether, nonafluorobutyl methyl ether, trifluorotoluene, m-difluorotrifluorotoluene, perfluorocyclic ether, and perfluorohexane; and / or The non-fluorinated ether solvents include at least one of tetrahydrofuran, dioxane, methyl tert-butyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, and tetraethylene glycol dimethyl ether.

16. The preparation method according to claim 7, characterized in that, The molar ratio of the ketone-based perfluoropolyether to fluorinating agent A and fluorinating agent B is 1:1.5-10.

17. The preparation method according to claim 7, characterized in that, The conditions for the first and second fluorination reactions independently include: a reaction temperature of 0-100°C and a reaction time of 1-72 h; and / or The first and second purification methods include: extraction in the presence of an extractant and an alkali, and removal of the extractant from the liquid phase extract.

18. The preparation method according to claim 17, characterized in that, The alkali includes at least one of potassium hydroxide, sodium hydroxide, calcium hydroxide, potassium carbonate, sodium carbonate, sodium bicarbonate, sodium methoxide, sodium ethoxide, potassium tert-butoxide, and ammonia water; and / or The extractant is selected from organic alcohol compounds.

19. The preparation method according to claim 18, characterized in that, The organic alcohol compounds include C1-C4 alcohols and / or fluorinated C1-C4 alcohols.

20. A functionalized perfluoropolyether in a fluorinated chain, characterized in that, The functionalized perfluoropolyether in the fluorinated chain is prepared by the preparation method described in any one of claims 7-19.

21. The use of the fluorinated chain functionalized perfluoropolyether according to any one of claims 1-6 or the fluorinated chain functionalized perfluoropolyether according to claim 20 in modified rubber.

22. A modified perfluoroether rubber, characterized in that, The modified perfluoroether rubber is obtained by vulcanizing a perfluoroether rubber with a fluorinated chain functionalized perfluoropolyether as described in any one of claims 1-6 or the fluorinated chain functionalized perfluoropolyether as described in claim 20.

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