Preparation method of high-molecular-weight perfluoropolyether

Abstract

The invention belongs to the technical field of fluorine chemical industry, and particularly relates to a preparation method of high-molecular-weight perfluoropolyether, which comprises the following steps: step A, carrying out addition reaction on perfluoropolyether acyl fluoride through a solid catalyst loaded with a metal compound to obtain an intermediate mixture containing perfluoropolyether ketone and perfluoropolyether olefin; and B, carrying out a fluorination reaction on the intermediate mixture obtained in the step A by using a diluted fluorinating agent to obtain the high-molecular-weight perfluoropolyether. Compared with the prior art, the preparation method has the advantages that the problems of high synthesis difficulty and low yield of high-molecular-weight perfluoropolyether due to overlong molecular chain in the prior art are solved; in order to solve the problem, the inventor of the application successfully develops a new path for preparing the high-molecular-weight perfluoropolyether through a large amount of deep research, and the method prepares a higher-molecular-weight product through an acyl fluoride addition reaction of the two-molecular perfluoropolyether, so that the problem of low yield of the existing high-molecular-weight product is successfully solved.

Description

Technical Field

[0001] The invention belongs to the technical field of fluorine chemical industry, and in particular relates to a method for preparing high molecular weight perfluoropolyether. Background Art

[0002] Perfluoropolyether (PFPE) is a high molecular polymer with unique properties. It is widely used in aerospace, electronics, chemical industry, machinery and medicine due to its high temperature resistance, oxidation resistance, radiation resistance, corrosion resistance, low volatility, non-combustion and excellent lubricity. The molecular structure of PFPE contains fluorine atoms and ether bonds, which give it extremely high chemical and thermal stability.

[0003] Ultra-high molecular weight perfluoropolyether has more excellent performance, which makes it widely used in high temperature, high chemical inertness and excellent lubricity. For example, it has high temperature stability: it can maintain performance at extremely high temperatures, suitable for aerospace and other fields; excellent chemical inertness: it has good resistance to strong acids, strong alkalis and oxidants; ultra-low volatility: it is not easy to volatilize at high temperatures, suitable as vacuum pump oil; good lubricity under extreme conditions: suitable for lubrication of various mechanical parts; and radiation resistance: it can maintain performance even in radiation environments, suitable for nuclear industry, etc. Therefore, the application fields of high molecular weight perfluoropolyether include: as vacuum pump oil in high vacuum systems; lubricating oil for mechanical parts in high temperature and chemical corrosion environments; as insulating and lubricating materials in the semiconductor manufacturing process; used in the manufacture of artificial joints and other parts that require low friction coefficients and high chemical stability.

[0004] At present, the maximum molecular weight of perfluoropolyether is about 10,000. Due to the long molecular chain, the difficulty of synthesis is greatly increased, resulting in very small output. In addition, the separation difficulty of products with a molecular weight above 6,000 is also increased, and it is difficult to separate. Only a small number of manufacturers are able to produce and apply it, and there is little output in China.

[0005] For example, CN115558114A discloses a method for preparing perfluoropolyether oil, which comprises subjecting a perfluoropolyether raw material containing an acyl fluoride group and / or a carboxylic acid group to an esterification or amidation reaction with a precursor compound containing an alcoholic hydroxyl group or an amino group to obtain a perfluoropolyether block copolymer precursor; subjecting the perfluoropolyether block copolymer precursor to a primary element fluorination reaction to obtain a perfluoropolyether block copolymer; hydrolyzing the perfluoropolyether block copolymer under the catalysis of a perfluoropolyether carboxylic acid to obtain a perfluoropolyether carboxylic acid mixture; and subjecting the perfluoropolyether carboxylic acid mixture to a secondary element fluorination reaction to obtain a perfluoropolyether oil.

[0006] For example, CN115246928A discloses a perfluoropolyether oil and a preparation process and device thereof, wherein a polytetrafluoroethylene-supported cobalt difluoride catalyst having a porous structure is used to catalyze a fluorination reaction of perfluoropolyether acyl fluoride and / or perfluoropolyether carboxylic acid and a fluorinating agent to obtain perfluoropolyether oil.

[0007] The above-mentioned prior art can only be used to process and synthesize low-molecular-weight perfluoropolyether oils, and it is difficult to obtain high-molecular-weight perfluoropolyethers with better performance and wider application.

[0008] Therefore, it is necessary to propose a preparation method that can conveniently prepare high molecular weight perfluoropolyether to strengthen the domestic production of high molecular weight perfluoropolyether. Summary of the invention

[0009] The purpose of the present invention is to provide a method for preparing high molecular weight perfluoropolyether in order to solve at least one of the above problems, thereby solving the problems of high molecular weight perfluoropolyether in the prior art due to too long molecular chain, great difficulty in synthesis and low yield. In order to solve the above problems, the inventors of the present application have successfully developed a new preparation route for high molecular weight perfluoropolyether after extensive and in-depth research. This method prepares higher molecular weight products through two-molecule addition reaction, successfully solving the problem of low yield of existing high molecular weight products.

[0010] The purpose of the present invention is achieved through the following technical solutions:

[0011] A method for preparing a high molecular weight perfluoropolyether comprises the following steps:

[0012] Step A: performing an addition reaction on perfluoropolyether acyl fluoride by a solid catalyst supported by a metal compound to obtain an intermediate mixture containing perfluoropolyether ketone and perfluoropolyether olefin;

[0013] Step B: using a diluted fluorinating agent to carry out a fluorination reaction on the intermediate mixture obtained in step A to obtain the high molecular weight perfluoropolyether.

[0014] Preferably, in step A, the metal compound comprises a solid compound of a metal element of Group I, Group II or Group II, and the solid catalyst comprises a porous substance.

[0015] Preferably, the metal compound comprises a solid compound of an oxide, hydroxide or carbonate compound of a metal element of Group I, Group II or Group II, and the solid catalyst comprises a molecular sieve, silicon oxide and activated carbon.

[0016] Preferably, the metal compound is loaded in the solid catalyst in an amount of 0.5-20%.

[0017] Preferably, the metal compound is loaded in the solid catalyst in an amount of 1-10%.

[0018] Preferably, in step A, the temperature of the addition reaction is 80-200°C.

[0019] Preferably, the temperature of the addition reaction is 100-180°C.

[0020] Preferably, in step B, the diluted fluorinating agent is a fluorinating agent diluted with a protective gas.

[0021] Preferably, the protective gas is nitrogen or argon, and the fluorinating agent is selected from one or more of fluorine, sulfur tetrafluoride, sulfur hexafluoride and boron trifluoride; the molar ratio of the protective gas to the fluorinating agent is 10:0.2-10.

[0022] Preferably, in step B, the temperature of the fluorination reaction is 20-200° C. During the reaction, the reaction temperature can be appropriately increased within this range to reduce the kinematic viscosity of the perfluoropolyether, thereby increasing the mixing effect.

[0023] The working principle of the present invention is: two molecules of perfluoropolyether acyl fluoride react with a catalyst to cause acyl fluoride groups to undergo condensation reaction to form perfluoropolyether ketone and perfluoropolyether olefin; then, under the action of a fluorinating agent, the ketone group and olefin are eliminated to form perfluoropolyether.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The method of the present invention can double the molecular weight of perfluoropolyether by an addition method based on the raw materials, thereby solving the problem of low yield of high molecular weight perfluoropolyether products.

[0026] The method of the present invention is combined with conventional polymerization technology, and the molecular weight of the prepared perfluoropolyether product can be flexibly adjusted according to target requirements, and perfluoropolyether products with an average molecular weight of more than 4000 can be mass-produced, making up for the lack of domestic production of high molecular weight perfluoropolyether products. DETAILED DESCRIPTION

[0027] The present invention is described in detail below with reference to specific embodiments, but this is by no means a limitation of the present invention.

[0028] In the following description, unless otherwise specified, conventional commercially available products are used and the methods used are well known in the art.

[0029] A method for preparing a high molecular weight perfluoropolyether comprises the following steps:

[0030] Step A: performing an addition reaction on perfluoropolyether acyl fluoride by a solid catalyst supported by a metal compound to obtain an intermediate mixture containing perfluoropolyether ketone and perfluoropolyether olefin;

[0031] Step B: using a diluted fluorinating agent to carry out a fluorination reaction on the intermediate mixture obtained in step A to obtain the high molecular weight perfluoropolyether.

[0032] The preparation method provided by the present invention has a reaction process as shown in the following reaction formula:

[0033] Reaction 1:

[0034]

[0035] Reaction 2:

[0036]

[0037] Reaction 3:

[0038]

[0039] Among them, reaction formula 1-3 represents the reaction principle of perfluoropolyether acyl fluoride;

[0040] Reaction formula 1 is a reaction formula for preparing a perfluoropolyether intermediate mixture by addition of a perfluoropolyether acyl fluoride catalyst;

[0041] Reaction formula 2 is a reaction formula for preparing perfluoropolyether by fluorination of perfluoropolyetherketone in the intermediate mixture;

[0042] Reaction formula 3 is a reaction formula for preparing perfluoropolyether by fluorination of perfluoropolyether olefin in the intermediate mixture.

[0043] In step A:

[0044] The metal compound comprises a solid compound of an oxide, hydroxide or carbonate compound of a metal element of the first main group, the second main group or the sub-group; the solid catalyst comprises a molecular sieve, silicon oxide and activated carbon; the loading content of the metal compound in the solid catalyst is 0.5-20%, preferably 1-10%.

[0045] The temperature of the addition reaction is 80-200°C, preferably 100-180°C.

[0046] In step B:

[0047] The diluted fluorinating agent is a fluorinating agent diluted with a protective gas, the protective gas is nitrogen or argon, and the fluorinating agent is selected from one or more of fluorine, sulfur tetrafluoride, sulfur hexafluoride and boron trifluoride; the molar ratio of the protective gas to the fluorinating agent is 10:0.2-10.

[0048] The temperature of the fluorination reaction is 20-200° C. During the reaction, the reaction temperature can be appropriately increased within this range to reduce the kinematic viscosity of the perfluoropolyether, thereby increasing the mixing effect.

[0049] In the following examples, the method of the present invention is illustrated by specific experiments. It should be understood that these examples are merely illustrative and not restrictive.

[0050] Example 1

[0051] A fixed bed reaction system was used, 100 kg of 5 wt% sodium carbonate / activated carbon catalyst was loaded into a fixed bed reactor, the system was purged with nitrogen, the reactor temperature was raised to 150°C, 100°C preheated perfluoropolyether oleyl fluoride (average molecular weight 4000) was passed through a 130°C preheater at a speed of 60 kg / h, and then entered the reactor. After the reaction, the liquid material passed through the intermediate tank and was introduced into the tubular reactor in parallel with fluorine nitrogen gas with a fluorine content of 20%. The liquid material flow rate was maintained at 60 kg / h, and the fluorine nitrogen flow rate was 2 Nm 3 / h, and the reactor temperature was maintained at 100°C. After the reaction was completed, the fluorine gas and hydrogen fluoride were removed under reduced pressure at 100°C to obtain the final product.

[0052] The product was tested by GPC and the average molecular weight was 7800.

[0053] Example 2

[0054] A fixed bed reaction system was used, 100 kg of 5 wt% potassium carbonate / activated carbon catalyst was loaded into a fixed bed reactor, the system was purged with nitrogen, the reactor temperature was raised to 130°C, 100°C preheated perfluoropolyether oleyl fluoride (average molecular weight 4000) was passed through a 130°C preheater at a speed of 60 kg / h, and then entered the reactor, the liquid material after the reaction passed through the middle tank and was introduced into the tubular reactor in parallel with fluorine nitrogen gas with a fluorine content of 20%, the liquid material flow rate was maintained at 60 kg / h, and the fluorine nitrogen flow rate was 2 Nm 3 / h, and the reactor temperature was maintained at 130° C. After the reaction was completed, the fluorine gas and hydrogen fluoride were removed under reduced pressure at 130° C. to obtain the final product.

[0055] The product was tested by GPC and the average molecular weight was 7600.

[0056] Example 3

[0057] A fixed bed reaction system was used, 100 kg of 3 wt% potassium carbonate / molecular sieve catalyst was loaded into a fixed bed reactor, the system was purged with nitrogen, the reactor temperature was raised to 150°C, 100°C preheated perfluoropolyether oleyl fluoride (average molecular weight 4500) was passed through a 130°C preheater at a speed of 40 kg / h, and then entered the reactor, the liquid material after the reaction passed through the intermediate tank and then was introduced into the tubular reactor in parallel with fluorine nitrogen gas with a fluorine content of 30%, the liquid material flow rate was maintained at 40 kg / h, and the fluorine nitrogen flow rate was 1.5 Nm 3 / h, and the reactor temperature was maintained at 130° C. After the reaction was completed, the fluorine gas and hydrogen fluoride were removed under reduced pressure at 130° C. to obtain the final product.

[0058] The product was tested by GPC and the average molecular weight was 9000.

[0059] Example 4

[0060] A fixed bed reaction system was used, 100 kg of 5 wt% potassium carbonate / molecular sieve catalyst was loaded into a fixed bed reactor, the system was purged with nitrogen, the reactor temperature was raised to 120°C, 100°C preheated perfluoropolyether oleyl fluoride (average molecular weight 2000) was passed through a 130°C preheater at a speed of 40 kg / h, and then entered the reactor, the liquid material after the reaction passed through the intermediate tank and then was introduced into the tubular reactor in parallel with fluorine nitrogen gas with a fluorine content of 30%, the liquid material flow rate was maintained at 40 kg / h, and the fluorine nitrogen flow rate was 1.5 Nm 3 / h, and the reactor temperature was maintained at 130° C. After the reaction was completed, the fluorine gas and hydrogen fluoride were removed under reduced pressure at 130° C. to obtain the final product.

[0061] The product was tested by GPC and the average molecular weight was 4000.

[0062] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A method for preparing a high molecular weight perfluoropolyether, characterized in that: The steps include: Step A: performing an addition reaction on perfluoropolyether acyl fluoride by a solid catalyst supported by a metal compound to obtain an intermediate mixture containing perfluoropolyether ketone and perfluoropolyether olefin; Step B: using a diluted fluorinating agent to carry out a fluorination reaction on the intermediate mixture obtained in step A to obtain the high molecular weight perfluoropolyether.

2. The method for preparing a high molecular weight perfluoropolyether according to claim 1, characterized in that: In step A, the metal compound comprises a solid compound of a metal element of Group I, Group II or Group II, and the solid catalyst comprises a porous substance.

3. The method for preparing a high molecular weight perfluoropolyether according to claim 2, characterized in that: The metal compound includes a solid compound of oxide, hydroxide or carbonate compound of metal elements of the first main group, the second main group or the sub-group, and the solid catalyst includes molecular sieve, silicon oxide and activated carbon.

4. The method for preparing a high molecular weight perfluoropolyether according to claim 1, characterized in that: The loading content of the metal compound in the solid catalyst is 0.5-20%.

5. The method for preparing a high molecular weight perfluoropolyether according to claim 4, characterized in that: The loading content of the metal compound in the solid catalyst is 1-10%.

6. The method for preparing a high molecular weight perfluoropolyether according to claim 1, characterized in that: In step A, the temperature of the addition reaction is 80-200°C.

7. The method for preparing a high molecular weight perfluoropolyether according to claim 6, characterized in that: The temperature of the addition reaction is 100-180°C.

8. The method for preparing a high molecular weight perfluoropolyether according to claim 1, characterized in that: In step B, the diluted fluorinating agent is a fluorinating agent diluted with a protective gas.

9. The method for preparing a high molecular weight perfluoropolyether according to claim 8, characterized in that: The protective gas is nitrogen or argon, and the fluorinating agent is selected from one or more of fluorine, sulfur tetrafluoride, sulfur hexafluoride and boron trifluoride; the molar ratio of the protective gas to the fluorinating agent is 10:0.2-10.

10. The method for preparing a high molecular weight perfluoropolyether according to claim 1, characterized in that: In step B, the temperature of the fluorination reaction is 20-200°C.